Process for the preparation of a cross-linked hydrogel

Translation of description of equivalent WO 03104299 A1

A process for the preparation of esters of polyalcohols

description

The present invention relates to a simplified process for the esterification of unsaturated acids with polyalcohols, and use of the reaction mixtures thus obtainable.

Swellable hydrogel-forming polymers, known as superabsorbent (super Absorbing polymer, SAP), are known from the prior art. These are networks of flexible hydrophilic polymers, which can be both ionic and nonionic in nature. These are able to absorb aqueous liquids to form a hydrogel and to bind and are therefore preferably used for manufacturing tampons, diapers, sanitary napkins, incontinence articles, training pants for children, insoles and other hygiene articles for the absorption of body fluids. Superabsorbents are also used in other fields of technology where fluids, especially water or aqueous solutions, are absorbed. These areas include for example storage, packaging, transportation (packaging material for water-sensitive articles, for example flower transportation, shock protection); Food sector (transportation of fish, fresh meat; absorption of water, blood in fresh fish / meat packs); Medicine (wound plasters, water-absorbent material for burn dressings or for other weeping wounds), cosmetics (carrier material for pharmaceuticals and medicaments, rheumatic plasters, ultrasound gel, cooling gel, cosmetics tikverdicker, sunscreen); Thickeners for oil / water or water / oil emulsions; Textiles (gloves, sportswear, moisture regulation in textiles, shoe inserts); chemical process industry. Applications (catalyst for organic reactions, immobilization of large functional molecules (enzymes), adhesive for agglomerations, heat storage media, filtration aids, hydrophilic component in polymer laminates, dispersants, liquefiers.); Building and construction, installation (powder injection molding, clay plasters, vibration inhibiting medium, assistants in relation to tunneling in water-rich ground, cable sheathing); Water treatment, waste treatment, water removal (deicers, reusable sandbags); Cleaning; Agriculture industry (irrigation, retention of meltwater and dew precipitates, com- stierungszusatz, protection of forests against fungal / insect infestation, delayed release of active ingredients to plants); fire protection (flying sparks) (covering houses or covering house walls with SAP gel, since water has a very high heat capacity, ignition can be prevented; spraying of SAP gel in Fires such as forest fires); Coextrusion agent in thermoplastic polymers (hydrophilization of multilayer films); Production of films and thermoplastic moldings capable of absorbing water (eg storing rain and dew agricultural films); SAP-containing films for keeping fresh fruit and vegetables which can be packed in moist films; the SAP stores water discharged from fruits and vegetables without forming condensation droplets and returns the water partial to the fruits and vegetables again, so that neither fouling nor wilting occurs; SAP polystyrene coextrudates for example for food packaging such as meat, fish, poultry, fruits and vegetables); Carrier substance in formulations of active substances (Phar a, plant protection). Within hygiene articles, the supermarkets are absorber usually in so-called. Absorbent core which comprises as other materials, including fibers (cellulose fibers), the spontaneously applied liquid insults amounts caching and efficient channelization of the body fluids in the absorbent core toward as a kind of liquid to ensure the superabsorbent.

The current trend in diaper design is toward ever thinner constructions having a reduced cellulose fiber content and an increased hydrogel. With the trend toward ever thinner diaper constructions the requirements profile has changed significantly to the water-swellable hydrophilic polymers over the years. While at the beginning of the development of highly absorbent hydrogels it was initially solely the very high swellability on which interest focused later shown that the ability of the superabsorbent to Fluid transmission and distribution is crucial. It has been found that conventional superabsorbents greatly swell at the surface on wetting with liquid, so that transportation of liquid is very difficult into the particle interior or completely prevented. This trait of superabsorbents is also referred to as "gel blocking". The greater amount of the hygiene article (polymer per unit area), the polymer in the swollen state must not form a barrier layer to subsequent fluid. A product having good transportation properties, an optimal utilization of the entire hygiene article can be ensured. The phenomenon of gel blocking, thereby preventing the leading in extreme cases to the escape of liquid, the so-called. Leakage of the hygiene article applies. Fluid transmission and distribution is thus to the initial absorption of body fluids is crucial. Good transportation properties are possessed for example by hydrogels having high gel strength in the swollen state. Gels lacking in strength are deformable under an applied pressure (body pressure), clog the pores in the superabsorbent / cellulose fiber absorbent and so prevent continued absorption of fluid. Enhanced gel strength is usually achieved by increasing the cross-linking, which, however, the retention of the product is reduced. An elegant way to enhance gel strength is surface postcrosslinking is. In this process, dried

Superabsorbents having an average crosslink density subjected to additional crosslinking. By surface postcrosslinking increases the crosslink density in the sheath of the superabsorbent particle, whereby the absorption under pressure load to a higher level. Whereas the absorption capacity decreases in the superabsorbent particle sheath, the core of the superabsorbent particles by the presence of mobile polymer chains improved compared to the shell absorption capacity, so that sheath construction improved liquid ensures keitsweiterleitung without the the gel blocking effect. It is perfectly desirable for the total capacity of the superabsorbent is exhausted not spontaneously but at different times. Since the hygiene article is generally repeatedly insulted usually with urine, the absorption capacity of the superabsorbent should sensibly not be exhausted after the first disposition.

Hydrophilic, highly swellable hydrogels are in particular polymers of (co) polymerized hydrophilic monomers, graft (co) polymers of one or more hydrophilic monomers on a suitable grafting base, crosslinked cellulose or starch ethers, crosslinked carboxymethylcellulose, partially crosslinked polyalkylene oxide or swellable in aqueous liquids natural products, for example guar derivatives. Such hydrogels are used as aqueous solutions absorbing products to produce diapers, tampons, sanitary napkins and other sanitary products, but also as water-retaining agents in market gardening.

To improve their performance characteristics, such as diaper rewet and AUL, are hydrophilic, highly swellable hydrogels are generally surface or gel postcrosslinked. This postcrosslinking is known to those skilled in the art and is preferably in the aqueous gel phase or as surface of pre- ground and classified polymer particles. WO 93/21237 discloses (meth) acrylates of alkoxylated polyhydric C₂ Known Cio-hydrocarbons as crosslinkers -. These may be used as a mixture with by-products from the production process. 5

A disadvantage of these compounds is that for at least partial removal of starting materials and by-products - the crosslinkers used in the reference cited have an acrylic acid content of less than 0.1% by weight on - consuming cleaning 10 management operations are required.

The preparation of such higher (meth) acrylic acid esters by acid-catalyzed esterification of (meth) acrylic acid with the corresponding alcohols in the presence of an inhibitor / Inhibitorsy- 15 stems and optionally a solvent, such as benzene, toluene, cyclohexane, is generally known.

As is well known, acrylic acid formation of the ester of (meth) and alcohol is an equilibrium reaction based, is to achieve 20 economical conversions, a starting material generally used in excess and / or remove the esterification water formed and / or the target ester from the equilibrium ,

25 Therefore, the water of reaction from the production of the higher (meth) acrylic acid ester is typically employed and usually an excess of (meth) acrylic acid.

US 4,187,383 describes an esterification process of 30 (meth) acrylic acid with organic polyols at a reaction temperature of 20 to 80 ° C with an equivalent excess of 2 to 3: 1st

A disadvantage of this method is that amount by the low reaction temperature 35 tion, the reaction times up to 35 hours and the excess acid is removed in the reaction mixture by neutralization followed by phase separation.

WO 2001/14438 (. Derwent Abstract No. 2001-191644 / 19) and WO 2001/10920 40 (Chemical Abstracts 134: 163502) describe processes for esterifying (meth) acrylic acid with Polyalkylenglykolmonoal- kylethern in the ratio 3: 1 - 50: 1 in the presence of acids and polymerization inhibitors and, after deactivation of the acidic catalyst, copolymerization of the residue of (meth) acrylic acid ester 45, and (meth) acrylic acid at pH 1.5 to 3.5, and its use as a cement additive. A disadvantage of this method is that it is limited to monoalkyl polyalkyleneglycol- that the catalyst must be deactivated and that such copolymers can not be used as crosslinkers for hydrogels since they only have one functionality.

The object was to simplify the process for preparing substances which are useful as radical crosslinkers for superabsorbents.

The object is achieved by a process for preparing an ester F of a polyhydric alcohol A having at least one ethylenically unsaturated carboxylic acid B, comprising the steps a) reaction of a polyol A having at least one ethylenically unsaturated carboxylic acid B in the presence of at least one esterification catalyst C and of at least one polymerization inhibitor D and, optionally, one forms an azeotrope with water solvent e to form an ester F, b) optionally removing at least a portion of the formed in a) water from the reaction mixture, b), during and / or after a) take place, f) optionally, neutralizing of the reaction mixture, h) when a solvent e was used this solvent decision optionally distant by distillation and / or i) stripping with an inert gas under the reaction conditions, wherein

- Having the polyalcohol A least two hydroxyl functions,

- The molar excess of the ethylenically unsaturated carboxylic acid B to the polyhydric alcohol to be esterified, depending A hydroxy group in A is at least 1.05: 1, and

- Contained in the reaction mixture obtained after the last step, optionally neutralized carboxylic acid B substantially remains in the reaction mixture.

The molar excess of B to A is (per hydroxy group to be esterified polyalcohol in A) at least 1.05: 1, preferably at least 1.1: 1, more preferably at least 1.25: 1, very particularly preferably at least 1.5: 1 and especially at least 2.5: 1.

In a preferred embodiment B is in an excess of, for example greater than 5: 1, preferably greater than 10: 1, more preferably greater than 20: 1, most preferably greater than 50: 1, in particular greater than 75: 1 and especially greater than 100 : 1. The esterification products thus obtainable can substantially without further purification, specifically without substantial removal of the excess of carboxylic acid B and the content of esterification catalyst C, are used as radical crosslinkers in hydrogels.

Undercrosslinking is in this document, unless otherwise stated, the radical crosslinking (gel crosslinking, internal crosslinking, crosslinking of linear or lightly crosslinked polymer) were than comparable. This crosslinking can about radical or cationic polymerization mechanisms or other, for example Michael addition, esterification or U done esterungsmechanismen, preferably by radical polymerization.

Hydrogel-forming polymers are preferably capable of absorbing distilled water of at least the net weight, preferably 10 times their own weight, this absorption is preferably achieved even under a pressure of 0.7 psi.

According to the invention usable polyalcohols A are compounds containing at least two hydroxyl (-0H) have, preferably at least three, more preferably three to ten, most preferably three to six, and in particular three to four.

The polyhydric alcohols can be aliphatic, cycloaliphatic or aromatic, preferably aliphatic or cycloaliphatic, and most preferably aliphatic, straight chain or branched and optionally substituted with functional groups.

In general, the polyols have two to 50 Kohlenstoffato e and preferably from three to 40th

The molecular weight of the usable polyalcohols is generally, unless otherwise indicated, below 5000 g / mol, preferably below 2500 g / mol, more preferably below 1500 g / mol, very preferably below 1000 g / mol and in particular less than 800 g / mol.

Preferred polyalcohols A are polyols, functionalized polyols, alkoxylated polyols, sugar alcohols, partially alkoxylated sugar alcohols, polyetherols, polyesterols, at least partially alkoxylated polyesterols and at least partially hydrolyzed, alkoxylated polyesterols. Examples of polyols are trimethylolbutane, trimethylolpropane, trimethylolethane, neopentyl glycol, Hydroxypivalinsäureneopentyl- glycol ester, pentaerythritol, glycerol, 1, 2-ethylene glycol, 1,2-propylene glycol, 2-ethyl-l, 3-propanediol, 2-methyl-l, 3- Proρan- diol, hydroquinone, bisphenol A, bisphenol F, bisphenol B, 2, 2-bis (4-hydroxycyclohexyl) propane, 1,1-, 1,2-, 1,3- and 1, 4-cyclohexanedimethanol, 1, 2-, 1,3- or 1, -Cyclohexandiol, but-2-en-l, 4-diol and but-2-in-l, 4-diol.

The polyols may also bear additional functionalities such as ether functions (-0-), carboxyl (-C00H) or -C-C₄-Alkyloxycarbonylfunktionen (Ester groups), wherein -C-C₄Alkyl in this specification means methyl, ethyl, iso-propyl, n-propyl, n-butyl, iso-butyl, butyl or seλr-terfc-butyl.

Examples of such polyols are functionalized Ditrimethyl- propane, narrow dipentaerythritol, dimethylolpropionic acid, Dimethylolbut- tersäure, trimethylolacetic acid, hydroxypivalic acid and the 2-hydroxyethyl or -C-C₄Alkyl esters of said acids. Preferred polyols are those of the formula (I):

<img id="imgf000008_0001" he="18" wi="38" file="imgf000008_0001.tif" img-format="tif" img-content="drawing" orientation="portrait" inline="no" />

OH OH

In this reference

R¹, R² independently hydrogen, Ci - Cio-alkyl, preferably Ci - C₄Alkyl, Ci - Cio-hydroxyalkyl, preferably hydroxy-Ci - C₄Alkyl, carboxyl or Ci - C₄-alkyloxy Carbonyl, preferably hydrogen, hydroxymethyl, and C - C₄Alkyl, and more preferably hydroxymethyl and Ci - C₄Alkyl.

The alkyl radicals may each be linear or branched.

Examples of R¹ and R² are hydrogen, methyl, ethyl, iso-propyl, n-propyl, n-butyl, iso-butyl, SEFC-butyl, tert-butyl, n-pen- tyl, n-hexyl, n-heptyl, n-octyl, n -decyl, hydroxymethyl, carboxyl, methoxycarbonyl, ethoxycarbonyl or n-butoxycarbonyl, preferably hydrogen, hydroxymethyl, methyl and ethyl, particularly preferably hydroxymethyl, methyl and ethyl. Particularly preferred polyhydric alcohols of the formula (I) are trimethylolbutane, trimethylolpropane, trimethylolethane, neopentyl glycol, pentaerythritol, 2-ethyl-l, 3-propanediol,

2-methyl-l, 3-propanediol, 1, 3-propanediol, dimethylolpropionic Dimethylolpropionsäuremethylester, Dimethylolpropionsäureethyle- art, dimethylol, Dimethylolbuttersäuremethylester or Dimethylolbuttersäureethylester, preferred are neopentyl glycol, trimethylolpropane, pentaerythritol and dimethylolpropionic, very preferably neopentylglycol, tri- propane and pentaerythritol, and in particular trimethylolpropane and pentaerythritol.

Examples of sugar alcohols include sorbitol, mannitol, maltitol, isomalt, diglycerol, threitol, erythritol, Adonit (ribitol), arabitol (Lyman xit), xylitol and dulcitol (galactitol).

Examples of polyether polyols are poly-THF having a molar mass between 162 and 2000, preferably seen between 162 and 1458, more preferably between 162 and 1098, most preferably between 162 and 738 and in particular between 162 and 378,

Poly-1, 3-propanediol and poly-1, 2-propanediol having a molar mass between 134 and 1178, preferably 134-888, more preferably 134-598 un d most preferably 134-308, polyethylene glycol having a molecular weight between 106 and 898, preferably ethylene glycol 106-458, more preferably 106-400, most preferably between 106 and 235, and in particular diethylene glycol, triethylene glycol and tetra-.

Examples of suitable polyesterols are those which, as. By esterification of polycarboxylic acids, preferably dicarboxylic acids, can be prepared with the polyols mentioned above

The starting materials for such polyesterols those skilled known. 4-cyclohexanedimethanol preferably have the polycarboxylic oxalic acid, maleic acid, fumaric acid, succinic acid, adipic acid, sebacic, dodecanedioic, o-phthalic acid, terephthalic acid, trimellitic acid, azelaic acid, 1, carboxylic acid or tetrahydrophthalic acid, their isomers and hydrogenation products and esterifiable derivatives such as anhydrides or dialkyl esters, for example C₁-C₄Alkyl esters, preferably methyl, ethyl or n-butyl esters, of said acids.

As hydroxyl-containing carboxylic acids or lactones include 4-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, pivalolactone or ε-caprolactone into consideration. Suitable polyols include the abovementioned polyfunctional alcohols, preferably neopentylglycol, Trimethylolpropane, tri ethylolethan, pentaerythritol, dimethylolpropionic acid or dimethylolbutyric.

Preferred examples of such polyesterols are those of formula (Illa-c)

<img id="imgf000010_0001" he="29" wi="151" file="imgf000010_0001.tif" img-format="tif" img-content="drawing" orientation="portrait" inline="no" />

(Purple) (IIIb) (IIIc) wherein

R¹, R² have the abovementioned meanings and

Y atoms a straight-chain or branched, optionally substituted alkylene group having 2 to 20 carbon or an optionally substituted cycloalkylene or arylene group having 6 to 12 carbon atoms or a single bond

mean.

Examples of Y are a single bond, methylene, 1,2-ethylene, 1, 3-propylene, 1,4-butylene, 1,6-hexylene, 1, 7-heptylene, l, 8-0ctylen, cis-1, 2 -Ethenylen, trans-1, 2-ethenylene, 1,2-, 1,3- or 1, 4-phenylene, 1, 2-cyclohex-l-enylene, 1,2-, 1,3- or 1, 4 -Cyc1ohexy1en, 4-carboxy-1, 2-phenylene, 2-carboxy-1, 4-phenylene or l-carboxy-2, 4-phenylene.

Preferred groups Y are 1,2-ethylene, 1,4-butylene and 1,2-, 1,3- or 1, 4-phenylene.

are course preparation, in the rule before mixtures in which can be hold lower and higher oligomers corresponding addition.

In a further preferred embodiment, reaction mixtures are used of at least partially saponified polyesterols as polyalcohols A for producing the ester F. For this, the polyesterols described above are at least partially hydrolyzed with a suitable base, and then, optionally esterified after removal of remaining in the reaction mixture basic components, with the carboxylic acid B.

Suitable bases are, for example, NaOH, KOH, Ca (0H), milk of lime, NaC0₃ or KC0₃, For example as a solid, solution or suspension, preferably in the form of a 10-50% strength by weight solution, particularly preferably in the form of a 20-40% by weight aqueous solution.

The hydrolysis, ie cleavage of the ester groups contained in the polyester polyol is made to, for example, at least 10% relative to the ester groups in the starting compound, preferably at least 25%, more preferably at least 50%, very particularly preferably at least 75% and in particular at least 90%.

If basic components, such as the basic salt of the carboxylic acid to be removed from the reaction mixture, this can for example the ion exchange, effected, for example acidic or strongly acidic ion exchangers.

The reaction mixture is subsequently acidified and esterified with the carboxylic acid B as described.

Polyester (meth) acrylates can be used in a plurality of stages or else in one stage, as described for example in EP-A 279 303, acrylic acid from (meth), polycarboxylic acid and polyol.

Also suitable for use as polyols are alkoxylated polyols and polyester polyols, with at least one alkylene oxide are rols obtainable by reacting a polyol or Poleste-.

According to the invention, those compounds of formula VII may be prepared containing the reaction mixtures.

R^8th- (O (CH (R^l0) CH (R¹⁰)O)_y-C (= O) -R⁹)_x (VII)

wherein

R^8th is a polyvalent, straight-chain or branched C₂-Cιo-Alkyl radical, R⁹ independently a straight or branched C-Cιo-alkenyl radical, R¹⁰ are independently hydrogen or methyl, x independently a positive integer of 2 or greater, and y independently of one another = x 2 is a number from 3 to 8 and x = 3 or greater is a number 2 to 7

The underlying alcohol to be esterified in this case has the formula VIIa to,

R^8th- (0 (CH (R^l°) CH (R^lθ) 0)_y-H)_x (VIIa),

where R^8th, R¹⁰, X and y are as defined above.

The compounds of formula (VII) are generally 2 to 10 carbon atoms containing polyols VIIa which have been alkoxylated with 2-8 alkylene oxide units per hydroxyl group and whose terminal hydroxyl group each alkylene lenoxidkette with a 2 to 10 carbon atoms containing unsaturated carboxylic acid or its ester is esterified. Preferably the starting alcohol to a: 3 - 6 carbon atoms and having a polyhydric alcohol, which preferably carries 2 to 4 hydroxyl groups. Particularly preferably, the starting alcohol is trimethylolpropane, glycerol, pentaerythritol, 1, 3-propanediol, propylene glycol, 1, 4-butanediol or butylene. Most particularly preferred are trimethylolpropane, glycerol and pentaerythritol as the starter alcohol.

Suitable alkylene oxides are for example ethylene oxide, propylene oxide, isobutylene oxide, vinyl oxirane and / or styrene.

The alkylene oxide chain may preferably of ethylene oxide, propylene oxide and / or composed butylene. Such a chain can be composed of one species of an alkylene oxide or a mixture of alkylene oxides. If a mixture is used, the different alkylene oxide may be present randomly or as a block or blocks of individual species. Preferred as alkylene oxide is ethylene oxide, propylene oxide or a mixture thereof, more preferably it is ethylene oxide or propylene oxide and most preferably ethylene. Thus, preferably, a radical R¹⁰ alkylene oxide per hydrogen and the other is methyl or hydrogen, more preferably both R¹⁰ Hydrogen.

The preferred number of alkylene oxide units in each chain is dependent upon the number of chains.

The esterifying agent is a 2 to 10 carbon atoms aufwei- send, linear or branched ethylenically unsaturated carboxylic acid or its ester, preferably a 2 to 4 and particularly preferably a 2 to 3 carbon atoms which ethylenically unsaturated carboxylic acid, most preferably acrylic acid, methacrylic acid or their esters, in particular acrylic acid.

Often, the compounds of formula VII as mixture of compounds that are described by this formula, and by-products of the manufacturing process are.

Particularly preferred among these compounds VII are each hydroxy up to six times, more preferably up to four times and most preferably four times ethoxylated compounds, hereinafter referred to as compounds VIIb. These exhibit increased hydrolytic stability.

Likewise preferred compounds VII, each hydroxyl

- When x = 2 is more than eight times, especially preferably more than ten times, very particularly preferably more than twelve times and especially at least 15-fold, respectively - when x = 3 or greater more than seven times, particularly preferably more than nine times, very particularly preferably more than twelve times and in particular ethoxylated not less than 15, hereinafter referred to as compounds VIIc, since these generally have a high water solubility.

It is also conceivable such compounds VII, in which x = 2 for y values ​​of 0, 1 or 2 and y for x = 3 values ​​of 0 or 1 may take.

In particular, mixtures of the compounds VIIb and VIIc are advantageous, for example those with a weight ratio VIIb: VIIc from 10:90 to 90:10, preferably 20:80 to 80:20, more preferably 30:70 to 70:30, and most preferably from 40:60 to 60:40.

Preferred examples of such alkoxylated polyols are the alkoxylation products (Ha), (IIb) or (IIc) of polyols of formula (I), <img id="imgf000014_0001" he="23" wi="152" file="imgf000014_0001.tif" img-format="tif" img-content="drawing" orientation="portrait" inline="yes" />

(Ha) (IIb) ^(IIc &gt;

wherein

R¹, R² have the abovementioned meanings,

k, 1, m, q, independently of one another are each an integer from 1 to 10, preferably 1 to 5, particularly preferably 3 to

5 and in particular 4, and

each Xi for i = 1 to k, 1 to 1, 1 to m and 1 to q may be independently selected from the group - CH₂--CH₂_0-, -CH₂--CH (CH₃) -0-, -C (CH₃) -CH₂_0-,

-CH₂_C (CH₃)₂-0-, -C (CH₃)₂--CH₂_0-, -CH_CHVin-0-, -CHVin-CH₂_0-, -CH₂_CHPh 0 and -CHPh-CH₂-0-, Preferably from the group -CH₂--CH₂_0-, -CH₂--CH (CH₃) -O- And -CH (CH₃) -CH₂-0-, And more preferably -CH₂--CH₂-0-,

where Ph is phenyl and Vin is vinyl.

Preferably, these are one to five, more preferably three to five times, and most preferably four times ethoxylated, propoxylated or mixed ethoxylated and propoxylated and especially exclusively ethoxylated neopentylglycol, trimethylolpropane, trimethylolethane or pentaerythritol.

Among these, particularly preferred are those polyhydric alcohols of the formula (IIb).

Equally preferred is a one to 20 times, preferably one to ten times, more preferably two to ten times, most preferably two to five times, in particular three to five times, and especially three to four times as alkoxylated, ethoxylated preferably, propoxylated or mixed ethoxylated-propoxylated and particularly preferably ethoxylated glycerol (here exceptionally reckoned in moles of alkoxy groups per mole glycerin). The stated degrees of alkoxylation each relate to the average degree of alkoxylation.

The number average molecular weight M_n the alkoxylated polyols is preferably not more than 1000 g / mol, particularly preferably not more than 800 g / mol and very particularly preferably not more than 550 g / mol.

The information on the number average and weight average molecular weight M_n and M_w refer here to gel permeation graphical measurements using polystyrene as standard and tetrahydrofuran as eluent. The method is described in the analyst Paperback Vol. 4, pages 433 to 442, Berlin 1984.

Examples of alkoxylated sugar alcohols are those compounds which are obtainable from sugar alcohols, such as the sugar alcohols mentioned above, by alkoxylation, for example, with the above alkylene oxides, preferably with ethylene oxide and / or propylene, and most preferably with ethylene oxide. Examples are

the tetrols listed, the average per mole of sugar alcohol is 2 - 30 times, preferably 2 - 20 times, more preferably 3-10fach and in particular 3, 4, 5, 6, 7 or 8-way have been alkoxylated,

the Pentole listed, the average per mole of sugar alcohol 3 - are 35x, 3-28fach preferred, particularly preferred 4-20fach and especially 4, 5, 6, 7, 8, 9 or lOfach alkoxylated,

higher sugar alcohols, which are on average per mole of sugar alcohol 4-50fach, preferably 6-40fach, particularly preferably 7-30fach, most preferably and particularly 8-20fach 10-15fach alkoxylated.

Preferred alkoxylated sugar alcohols are those in which at least one hydroxyl group of the sugar alcohol is not alkoxylated.

Preferred examples of alkoxylated Polesterole are those of the formula (IVa-c), <img id="imgf000016_0001" he="36" wi="150" file="imgf000016_0001.tif" img-format="tif" img-content="drawing" orientation="portrait" inline="no" />

(IVa) (IVb)

<img id="imgf000016_0002" he="41" wi="76" file="imgf000016_0002.tif" img-format="tif" img-content="drawing" orientation="portrait" inline="no" />

(IVc)

wherein

R ^ R ^ Y have the abovementioned meanings, k, 1, m, q, r, s 1 to 10 and in particular 1 stands each independently for an integer from 1 to 30, preferably 1 to 20, particularly preferably up to 5 and

each Xi for i = 1 to k, 1 to 1, 1 to m, 1 to q, 1 r and 1 to s can be independently selected from the group -CH₂-CH₂_0-, -CH₂-CH (CH₃) -0-, -C (CH₃) -CH₂_0-, -CH₂_C (CH₃)₂-0-, -C (CH₃)₂--CH₂-0-, -CH₂_CHVin-0-, CH -CHVin-₂_0-, -CH₂-CHPh 0 and -CHPh-CH₂_0-, Preferably from the

-CH₂-CH₂_0-, -CH₂--CH (CH₃) -0- And -CH (CH₃) -CH₂_0-, And particularly preferably -CH_CH_0-,

where Ph is phenyl and Vin is vinyl,

mean.

Preferably, these are unalkoxyliertes or one- to ten-fold, more preferably two to five times ethoxylated, propoxylated or mixed ethoxylated and propoxylated, with adipic acid, phthalic acid or isophthalic verstertes neopentyl glycol, trimethylolpropane, trimethylolethane or pentaerythritol.

The reaction of the alcohols with an alkylene oxide is known to the skilled worker. Possible ways of conducting can be found in Houben-Weyl, Methods of Organic Chemistry, 4th Edition, 1979, Thieme Verlag Stuttgart, ed. Heinz Kropf, Volume 6 / la, part 1, pages 373-385.

Are mixed alkoxylated alcohols are used, the different alkoxy groups contained therein may each other in a molar ratio of, for example 0.05 to 20: 1, preferably from 0.1 to 10: 1 and more preferably from 0.2 to 5: stand. 1

The viscosity of the inventively employable polyalcohols no special demands are made, except that they should be readily pumpable at a temperature up to about 80 ° C, preferably they should have a viscosity below 1000 mPas, preferably below 800 mPas and most preferably below 500 mPas.

Are used as polyalcohols trivalent or more polyols in the esterification, it may be useful for their use according to the invention as radical, only partially esterified. This means that, in a n-werti- gene polyalcohol only at least 2 of n hydroxy groups are esterified with the carboxylic acid B.

For n = 3, the degree of esterification is at least 2, for n = 4 at least 2, preferably at least 2.5 and particularly preferably at least 3, for n = 5 or greater at least 2, preferably at least 3 and more preferably at least 4th

In such a case, the need to input stoichiometric excess of carboxylic acid B is calculated on the desired degree of esterification, ie is, for example, the 2 / n times the above molar excess. Naturally the esterification can also be, for example, terminated by cooling or dilution when the desired degree of esterification has been reached.

According to the invention Useful ethylenically unsaturated carboxylic acids B are those compounds having at least one carboxyl group (-COOH), preferably one and at least one, preferably at a ethylenically unsaturated group. The inventively employable carboxylic acids may be aliphatic, cycloaliphatic or aromatic, preferably aliphatic or cycloaliphatic and most preferably aliphatic, straight-chain or branched and optionally substituted with functional groups.

In general, the carboxylic acids have from three to ten carbon atoms, preferably three to five and most preferably three to four.

Examples of ethylenically unsaturated carboxylic acids B are acrylic acid, methacrylic acid, ethacrylic acid, maleic acid including its anhydride, fumaric acid, itaconic acid, citraconic acid, mesaconic acid, vinyl acetic acid, allylacetic acid or crotonic acid.

Preferred carboxylic acids B are α, ß-unsaturated carboxylic acids.

Particularly preferred are methacrylic acid and acrylic acid, in this document, (meth) acrylic acid mentioned, very particularly preferably acrylic acid.

According Useful esterification catalysts C are sulfuric acid, aryl or alkyl sulfonic acids or mixtures thereof. Examples of arylsulphonic are benzene, para-toluenesulfonic acid or dodecylbenzenesulfonic acid, examples of alkylsulphonic acids methanesulfonic acid or trifluoroacetic ethane sulfonic acid. Strongly acidic ion exchangers or zeolites are useful as esterification catalysts. Preferably sulfuric acid and ion exchangers.

According to the invention usable polymerization inhibitors D are, for example, phenols such as alkylphenols, for example o-, m- or p-cresol (methylphenol), 2-tert. Butyl-4-methyl phenol, 6-tert. -butyl-2-dimethyl-phenol, 2, 6-di-tert. -butyl-4-methylphenol, 2-tert. Butylphenol, 4-tert. Butylphenol, 2, -di-tert .- butylphenol, 2-methyl-4-tert. Butylphenol, 4-tert. -Bu- Tyl-2, 6-dimethylphenol, or 2, 2 '-methylene-bis- (6-tert. -bu- Tyl-4-methylphenol), 4, 4' -Oxydiphenyl, 3, 4-Methylendioxydiphenol (sesamol ), 3, 4-dimethylphenol, hydroquinone, catechol (1,2-dihydroxybenzene), 2- (1 '-Methylcyclohex-1' -yl) -4, 6-dimethyl- phenol, 2- or 4- (1 '- phenyl-eth-1 '-yl) phenol, 2-tert-butyl tyl-6-methylphenol, 2,4, 6-tris-tert-butylphenol, 2, 6-di-tert. butylphenol, 2, 4-di-tert. butylphenol, 4-tert. Butylphenol, nonyl phenol [11066-49-2], octyl phenol [140-66-9], 2, 6-dimethylphenol, bisphenol A, bisphenol F, bisphenol B, bisphenol C, bisphenol S, 3, 3 ', 5 , 5 '-Tetrabromobisphenol A, 2, 6-di-tert-butyl-p-cresol, co-Resin® from BASF AG, 3, 5-di-tert-butyl-4-hydroxybenzoate ester, 4-tert-butylcatechol, 2-hydroxybenzyl alcohol, 2-methoxy-4-methylphenol, 2, 3, 6-trimethylphenol, 2,4,5-tri-methylphenol, 2, 4, 6-trimethylphenol, 2-isopropylphenol, 4-iso-propylphenol, 6-isopropyl-m-cresol, n-octadecyl-SS- (3, 5-di-tert-bu- tyl-5 4-hydroxyphenyl) propionate,

1,1, 3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3, 5-trimethyl-2, 4, 6-tris- (3, 5-di-tert- butyl-4-hydroxy-benzyl) benzene, 1,3, 5, tris (3, 5-di-tert-butyl-4-hydroxy- benzyl) isocyanurate, 1,3,5, -tris (3, 5-di-tert-butyl-4-hydroxy-

10 phenyl) -propionyloxyethyl isocyanurate,

1,3, 5-tris- (2, 6-dimethyl-3-hydroxy-4-tert-butylbenzyl) isocyanurate or pentaerythritol tetrakis [SS- (3, 5-di-tert-bu- tyl-4 hydroxyphenyl) propionate], 2, 6-di-terfc. butyl-4-dimethylaniline minomethyl-phenol, 6-seλ:, .- butyl-2, 4-dinitrophenol, Irganox® 565

15 1141, 1192, 1222 and 1425 from Ciba Specialty Chemicals, 3- (3 ', 5' di-tert. Butyl-4 'hydroxyphenyl) propionsäureoctadecyle- art, 3- (3', 5 'di-tert . butyl-4 '-hydroxyphenyl) propionsäurehexa- decyl ester, 3- (3', 5 '-di-tert. -butyl' -hydroxyphenyl) propionic reoctylester, 3-thia-l, 5-pentanediol-bis- [ (3 ', 5' -di-tert. -bu-

20 tyl-4 '-hydroxyphenyl) propionate], 4, 8-dioxa-l, 11-undecandiol- bis [(3', 5 '-di-tert. Butyl-4' -hydroxyphenyl) propionate], 4, 8-dioxa-l, 11-undecanediol-bis [(3 '-tert. butyl-4' -hydroxy-5 '-methylphenyl) propionate], 1, 9-nonanediol bis [(3', 5 ' di-te -. butyl-4 'hydroxyphenyl) propionate], 1, 7-Heptandiamin-

25 bis [3- (3 ', 5' -di-ter.-Butyl-4 'hydroxyphenyl) propionamide], 1, 1-menthane-bis [3- (3', 5 '-di-ter. Butyl -4 'hydroxyphenyl) propionamide], 3- (3', 5 '-di-tert. butyl-4' hydroxyphenyl) propionic acid hydrazide, 3- (3 ', 5' -di-methyl-4 '-hydroxyphenyl) propionic acid hydrazide. Bis (3-fcert. Butyl-5-ethyl-2-hydroxy-

30 phen-l-yl) methane, bis (3, 5-di-tert-butyl-4-hydroxy-phen-l-yl) methane, bis [3- (1 '-methylcyclohex-1' -yl). - 5- methyl-2-hydroxy-phen-l-yl] methane, bis (3-tert-butyl tyl-2-hydroxy-5-methyl-phen-l-yl) methane, 1, 1-bis (5 -tert-butyl tyl-4-hydroxy-2-methyl-phen-l-yl) ethane, bis (5-tert-butyl

35 tyl-4-hydroxy-2-methyl-phen-l-yl) sulfide, bis (3-terfc. -Bu- Tyl-2-hydroxy-5-methyl-phen-l-yl) sulfide,

1, 1-bis (3, 4-dimethyl-2-hydroxy-phen-l-yl) -2-methyl propane, 1, 1-bis (5-tert. Butyl-3-methyl-2-hydroxy-phen- l-yl) -butane, 1,3, 5-tris [l '- (3' ', 5' -di-ter-butyl-4 '' hydroxy.

40 phen-1 '-yl) -meth-1' -yl] -2, 4, 6-trimethylbenzene,

1,1, 4-tris (5 '-tert. Butyl-4' -hydroxy-2 'methyl-phen-1' -yl) butane, aminophenols, for example para-aminophenol, nitrosophenols, such as para-nitrosophenol , p-nitroso-o-cresol, alkoxyphenols, e.g., 2-methoxyphenol (guaiacol, pyrocatechol monomethyl ether) 5 2-ethoxyphenol, 2-isopropoxyphenol, 4-methoxyphenol (hydroquinone monomethyl ether), mono- or di-tert. -butyl-4-methoxyphenol, 3, 5-di-tert-butyl-4-hydroxyanisole, 3-hydroxy-4-methoxybenzylalko- hol, 2, 5-dimethoxy-4-hydroxybenzyl alcohol (Syringaalkohol), 4-hydroxy-3-methoxybenzaldehyde (vanillin), 4-hydroxy-3-ethoxyben- zaldehyd (ethyl vanillin), 3-hydroxy-4-methoxybenzaldehyde (isovanillin), l- (4-hydroxy-3-methoxy-phenyl) ethanone (acetovanillone), eugenol, Dihydroeugenol, isoeugenol, tocopherols such as α-, ß, Y ~. δ- and ε-tocopherol, tocol, α-Tocopherolhydrochinon, and 2, 3-dihydro-2, 2-dimethyl-7-hydroxybenzofuran (2, 2-dimethyl-7-hy droxycumaran), quinones and hydroquinones such as hydroquinone or hydroquinone , 2, 5-di it. -Butylhydrochinon, 2-methyl-p-hydroquinone, 2, 3-dimethylhydroquinone, Trimethylhydro- hydroquinone, 4-methylcatechol, tert-butylhydroquinone, 3-methyl-catechol, benzoquinone, 2-methyl-p-hydroquinone, 2, 3 dimethyl hydroquinone, trimethyl hydroquinone, 3-methylcatechol, 4-me- thylbrenzcatechin, tert-butylhydroquinone, 4-ethoxyphenol, 4-butoxy xyphenol, hydroquinone, p-phenoxyphenol, 2-methyl hydroquinone, 2, 5-di-tert .-butyl hydroquinone, tetramethyl-p-benzoquinone, diethyl-1, 4-cyclohexanedione-2, 5-dicarboxylate, phenyl-p-benzoquinone, 2, 5-dimethyl-3-benzyl-p-benzoquinone, 2-iso- propyl-5-methyl-p-benzoquinone (thymoquinone), 2, 6-diisopropyl-p- benzoquinone, 2, 5-dimethyl-3-hydroxy-p-benzoquinone, 2, 5-dihydroxy-p-benzoquinone, Embelin, tetrahydroxy -p-benzoquinone, 2,5-dimethoxy-1, 4-benzoquinone, 2-amino-5-methyl-p-benzoquinone, 2,5-Bisphe- nylamino-1, 4-benzoquinone, 5, 8-dihydroxy -l, 4-naphthoquinone, 2-arrival ilino-1, 4, naphthoquinone, anthraquinone, N, N-dimethylindoaniline, N, N-diphenyl-p-benzoquinonediimine, 1, 4-benzoquinone dioxime, Coeruli- gnon, 3.3 '-di-tert-butyl-5, 5' -dimethyldiphenochinon, p-rosolic acid (Aurin), 2, 6-di-tert-butyl-4-benzylidene-benzoquinone, 2, 5-di- tert.-amylhydroquinone, N -Oxyle such as 4-hydroxy-2, 2, 6, 6-tetramethyl-piperidine-N-oxyl, 4-oxo-2, 2,6, 6-tetramethyl-piperidine-N-oxyl, 4-acetoxy-2, 2 , 6, 6-tetramethyl-piperidine-N-oxyl, 2,2,6, 6-tetramethyl methyl-piperidin-N-oxyl, 4, 4 ', 4' '-tris (2,2,6, 6- tetramethyl-piperidine-N-oxyl) phosphite, 3-oxo-2, 2,5, 5-tetramethyl-pyrrolidin-N- oxyl, l-0xyl-2, 2,6, 6-tetramethyl-4-methoxypiperidine , l-0xyl-2, 2,6, 6-tetramethyl-4-trimethylsilyloxypiperidin, l-0xyl-2, 2,6, 6-tetramethylpiperidin-4-yl-2-ethylhexanoate, l-0xyl-2, 2,6 , 6-tetramethylpiperidin-4-yl stearate, l-0xyl-2, 2,6, 6-tetramethylpiperidin-4-yl-benzoate, l-0xyl-2, 2,6, 6-tetramethylpiperidin-4-yl ( 4-tert-butyl) benzoate, bis (l-oxyl-2, 2,6, 6-tetramethylpiperidin-4-yl) succinate, bis (l-oxyl-2,2, 6, 6-tetramethylpiperidin-4-yl ) adipate, 1, 10-decanoic diacid bis (l-0xyl-2, 2,6, 6-tetramethylpiperidin-4-yl) ester, bis (l-oxyl-2, 2,6, 6-tetramethylpiperidin 4-yl) -n-butylmalonate, bis (l-oxyl-2,2, 6, 6-tetramethylpiperidin-4-yl) phthalate, bis (l-0xyl-2, 2,6, 6-tetramethylpiperidin-4- yl) isophthalate, bis (l-0xyl-2, 2,6, 6-tetramethylpiperidin-4-yl) terephthalate,

Bis (l-0xyl-2, 2,6, 6-tetramethylpiperidin-4-yl) -hexahydroterephtha- dimethacrylate, N, N'-bis (l-oxyl-2,2, 6, 6-tetramethylpiperidin-4-yl) -adipina- mid, N- (l-oxyl-2, 2,6, 6-tetramethylpiperidin-4-yl) caprolactam, N- (l-oxyl-2, 2,6, 6-tetramethylpiperidin-4-yl) -dodecylsuccinimid, 2,4, 6-tris- [N-butyl-N- (l-oxyl-2,2, 6, 6-tetramethyl-piperidin-4-yl] triazine, N, N '-bis (l-oxyl-2 , 2,6, 6-tetramethyl- piperidin-4-yl) -N, N'-bis-formyl-l, 6-diaminohexane, 4, 4 '-Ethylen- bis (l-oxyl-2,2, 6, 6-tetramethylpiperazin-3-one) aromatic amines such as phenylenediamines, N, N-diphenylamine, N-nitroso-diphenylamine, Nitrosodiethylanilin, N, N'-dialkyl-para-phenylenediamine, wherein the alkyl groups may be the same or different and are each inde- pendently consist of 1 to 4 carbon atoms and may be straight or branched, for example N, N'-di-iso-butyl-p-phenylenediamine, N, N'-di-iso-propyl-p-phenylenediamine, Irganox 5057 of the firm Ciba specialty Chemicals, N, N'-di-iso-butyl-p-phenylenediamine, N, N'-di-isσ-propyl-p-phenylenediamine, p- phenylenedi min, N-phenyl-p-phenylenediamine, N, N ' diphenyl-p-phenylenediamine, N-isopropyl-N-phenyl-p-phenylenediamine, N, N'Di- sec-butyl-p-phenylenediamine (Kerobit® BPD from BASF AG), N-phenyl-N'-isopropyl- p-phenylenediamine (Vulkanox 4010 by Bayer AG), N- (1, 3-dimethylbutyl) -N '-phenyl-p-phenylenediamine, N-phenyl-2-naphthylamine, Imoinodibenzyl, N, N'-diphenylbenzidine, N-Phe- nyltetraanilin, acridone, 3-hydroxydiphenylamine, 4-Hydroxydipheny- lamin, hydroxylamines such as N, N-diethylhydroxylamine, urea derivatives such as urea or thiourea, phosphorus-containing compounds such as triphenylphosphine, triphenyl phosphite, triethyl phosphite or hypo phosphorous acid, sulfur-containing

Compounds such as diphenyl sulfide, phenothiazine or metal salts, wiebeispielsweise copper, manganese, cerium, nickel, chromium chloride, dithiocarbamate, sulfate, acetate or salicylate, or mixtures thereof. Preferably, the mentioned phenols and quinones are particularly preferred are hydroquinone, hydroquinone monomethyl ether, 2-tert. -butyl-4-methylphenol, 6-tert. Butyl-2, 4-dimethyl-phenol, 2, 6-di-tert. -butyl-4-methylphenol, 2, 4-di-tert. Butylphenol, triphenyl phosphite, hypophosphorous acid, CuCl₂ and guaiacol, very particularly preferably hydroquinone and hydroquinone monomethyl ether are.

Particularly preferred are hydroquinone, hydroquinone and alkylphenols, optionally in combination with Tripehnyl- phosphite and / or hypophosphorous acid.

To further support the stabilization may be present an oxygen containing gas, preferably air or a mixture of air and nitrogen (air). Among the recited stabilizers, preferred are those which are aerobic, ie, those that require to develop their inhibiting effect, the presence of oxygen.

According to the invention usable solvents E are particularly those suitable for azeotropic removal of the water of reaction, if desired, are suitable, especially aliphatic, cycloaliphatic and aromatic hydrocarbons or mixtures thereof.

Preferably, n-pentane, n-hexane, n-heptane, cyclohexane come,

Methylcyclohexane, benzene, toluene or xylene. Particularly preferred are cyclohexane, methylcyclohexane and toluene.

For the esterification the conventional preparation and / or work-up process can be applied of polyols, such as the aforementioned or in DE-A 199 41 136, DE-A 38 43 843, DE-A 38 43 854, DE- A 199 37 911, DE-A 199 29 258, EP-A 331 845, EP 554 651 or US 4,187,383 described.

In general, the esterification can be carried out as follows:

The esterification apparatus comprises a stirred reactor, preferably a reactor with circulatory evaporator and an added distillation unit with condenser and phase separation vessel.

The reactor may be for example a reactor with jacketed heating and / or internal heating coils. Preferably, a reactor having an external heat exchanger and natural or forced circulation, ie using a pump, more preferably natural circulation where the Kreislaufström is accomplished without mechanical aids.

Of course, the reaction in several reaction zones, for example a reactor cascade consisting of two to four, preferably two or three reactors can be performed.

Suitable circulatory evaporators are known to one skilled in the art and described for example in R. Billet, evaporator technology, HTB Verlag, Bibliographical Institute Mannheim, 1965, 53. Examples of circulatory evaporators are tube heat exchangers, plate heat exchangers, etc. Of course there may be in circulation, several heat exchangers.

The distillation unit is of per se known type. It may be a simple distillation unit which is optionally equipped with a splash guard, or a rectification column. Useful column internals include in principle all common internals, for example trays, packings and / or dumped. Among the trays cap trays, sieve trays, valve trays, Thormann trays and / or dual-flow trays are preferred dumped packings are those of rings, coils, saddles or braids.

Typically 5 to 20 theoretical plates are sufficient.

The condenser and the separator vessel are of conventional design.

Carboxylic acid B and A are polyalcohol in the esterification a) usually in a molar excess as indicated above case based on the hydroxyl groups of the alcohol. The excess used can be up to about 1000: 1, if desired.

Useful esterification catalysts C include those recited above question.

They are usually in an amount of 0.1 - used 5% by weight, based on the esterification, preferably 0.5 - 5, more preferably from 1 - 4 and very particularly preferably 2 - 4% by weight.

If necessary, the esterification from the reaction mixture are removed by means of an ion exchanger. The ion exchanger can be added directly into the reaction mixture and then filtered off or the reaction mixture can be passed through an ion exchanger.

Preferably, the esterification catalyst is left in the reaction mixture. If, however, the catalyst is an ion exchanger, it is preferably removed, for example by filtration.

To further support the stabilization may be present an oxygen-containing gas, preferably air or a mixture of air and nitrogen (air). This oxygen-containing gas is preferably metered into the bottom region of a column and / or into a circulation evaporator and / or passed through the reaction mixture and / or about this.

The polymerization inhibitor (mixture) D (as mentioned above) in a total amount of 0.01 - used 1% by weight, based on the esterification, preferably 0.02 - 0.8, particularly preferably 0.05 - 0.5 weight %.

The polymerization inhibitor (mixture) D may be used for example as an aqueous solution or as a solution in a reactant or product.

b) The water of reaction formed during the reaction can be distilled off during or after the esterification of a), whereby this process can be supported by a forming an azeotrope with water.

Suitable solvents E for azeotropic removal of the water of reaction, if desired, include the compounds recited above.

Preference is given to carrying out the esterification in the presence of a solvent.

The amount of solvent used is from 10 to 200% by weight, preferably 20-100% by weight, particularly preferably 30 to 100% by weight based on the sum of polyol and carboxylic acid B.

However, conceivable is an operation without entrainer, for example, in DE-Al 38 43 854, column. 2, line 18 to column. 4, line 45 is described, however, in contrast with the stabilizers mentioned above.

If the water contained in the reaction mixture is not removed via an azeotrope-forming solvent, it is possible by stripping with an inert gas, preferably more preferably to remove an oxygen containing gas, air or lean air, for example, as described in DE-A 38 43 843..

The reaction temperature for the esterification a) is generally at 40-160 ° C, preferably 60-140 ° C and more preferably 80-120 ° C. The temperature may remain constant during the reaction or increase, preferably it is raised in the course of the reaction. In this case, the final temperature of the esterification by 5 - 30 ° C higher her than the initial temperature. The temperature for the esterification can be determined and controlled by varying the solvent concentration in the reaction mixture, as described in DE-A 199 41 136 and the German application with the file reference 100 63 175.4.

If a solvent is used, this can be distilled on the reactor distillation unit added from the reaction mixture.

The distillate may selectively be removed or, after condensation, fed into a phase separation apparatus. The aqueous phase thus obtained is discharged normally, the organic phase can be recycled as reflux into the distillation unit and / or directly into the reaction zone and / or fed into a circulatory evaporator as described in the German patent application with the file reference 100 63 175.4 described.

When used as reflux, the organic phase, as described in DE-A 199 41 136, are used to control the temperature in the esterification.

The esterification a) can pressure, at elevated pressure or accident are performed negative pressure, preferably under normal pressure.

The reaction time is usually 2-20 hours, preferably 4-15 and particularly preferably 7 to 12 hours.

The order of addition of the individual reaction components according to the invention is not essential. It can be presented mixed all components and then heated, or can not, one or more components or only partially provided sets and added only after heating.

The usable carboxylic acid B is not restricted in its composition and, in the case of crude (meth) acrylic acid, for example, comprise the following components:

(Meth) acrylic acid, from 90 to 99.9% by weight

Acetic acid 0.05 to 3% by weight

Propionic acid 0.01 to 1% by weight

Diacrylate 0.01 to 5 wt%

Water from 0.05 to 5% by weight

Carbonylics from 0.01 to 0.3 wt% Inhibitors from 0.01 to 0.1 wt%

Maleic acid (anhydride) from 0.001 to 0.5% by weight

The raw used (meth) acrylic acid is generally stabilized with 200-600 ppm of phenothiazine or other stabilizers in amounts which permit comparable stabilization. Under the Ausfruck Carbonylics here, for example, acetone and lower aldehydes, such as formaldehyde, acetaldehyde, crotonaldehyde, acrolein, 2- and 3-furfural and Benazaldehyd understood.

Crude (meth) acrylic acid here refers to the (meth) understood acrylic acid mixture which is obtained or is obtained after absorption of the reaction gases of the propane / propene / acrolein or isobutane / isobutene / methanol crolein oxidation in an absorbent and subsequent removal of the absorbent is recovered by fractional condensation of the reaction gases.

Of course, even pure (meth) acrylic acid are used with, for example, the following purity:

(Meth) acrylic acid, from 99.7 to 99.99% by weight

Acetic 50-1000 ppm propionic 10-500 ppm

Diacrylic 10-500 wt pm.

Water 50-1000 ppm

Carbonylics 1-500 ppm

Inhibitors 1-300 ppm maleic acid (anhydride) 1-200 ppm

The purity used (meth) acrylic acid is generally stabilized with 100-300 ppm of hydroquinone monomethyl ether or other storage stabilizers in amounts which permit comparable stabilization.

Under pure or prepurified (meth) acrylic acid is generally (meth) acrylic acid whose purity is at least. 99.5% by weight and which is substantially free of aldehydic, other carbonylic and high-boiling components.

The distilled off during the esterification of the aqueous phase through the column attached, if any, of the condensate removed, which generally from 0.1 to 10% by weight carboxylic acid B, for example, (meth) acrylic acid can anthalten, is separated and discharged. Advantageously, the carboxylic acid contained therein, for example, (meth) acrylic acid with an extractant, preferably the optionally used in the esterification Solvent, for example cyclohexane, at a temperature between 10 and 40 ° C and a ratio of aqueous phase to extractant of 1: 5-30, preferably 1: 10 - 20, be extracted and recycled to the esterification.

To further support the circulation, an inert gas, preferably an oxygen-containing gas, more preferably air or a mixture of air and nitrogen (lean air) into the circulation, through or over the reaction mixture, for example in amounts of 0.1 - 1. preferably from 0.2 to 0.8 and particularly preferably 0.3 to 0.7 m3 / m3h, based on the volume of the reaction mixture.

The course of the esterification a) can be followed by monitoring the issued of water carried out and / or the decrease in the carboxylic acid concentration in the reactor.

The reaction may for example be terminated as soon as 90% of the theoretically expected amount of water has been carried out by the solvent, preferably at least 95% and more preferably at least 98%.

Completion of the reaction can for example be found that substantially no further water of reaction is Removes over the entraining agent. If carboxylic acid B is discharged together with the water of reaction, its fraction is determinable for example by back-titration of an aliquot of the aqueous phase.

On removal of the reaction Waser example, can be dispensed with if the carboxylic acid B is used in a high stoichiometric excess, for example of at least 1.5: 1, preferably at least 2.5: 1 and most preferably at least 5: 1. In this case, a substantial portion of water formed in the reaction mixture remains tight. During or after the reaction, only the amount of water is removed from the reaction mixture, which is determined by the volatility at the employed temperature, and are also no measures for removing the water of reaction formed out. For example, at least 10 wt% of the remaining water of reaction formed in the reaction mixture, preferably at least 20%, more preferably at least 30% by weight, most preferably at least 40 and especially at least 50% by weight. c) After completion of the esterification, the reactor mixture may be cooled in a conventional manner to a temperature of 10 to 30 ° C and optionally by adding solvent that is the same as the optionally for azeotropic removal of water

may be 5 ser solvent used or another, be set any target ester concentration.

In a further embodiment, the reaction can be stopped with a suitable diluent G and at a concentra- 10 concentration of for example 10 - 90% by weight, preferably 20 - 80%, particularly preferably 20 to 60%, most preferably 30 to 50% and especially about 40%, for example to reduce the viscosity.

15 is important that forms an essentially homogeneous solution after dilution.

This preferably takes place only relatively shortly before use in the preparation of the hydrogel, for example not more than 24 hours 20 previously, preferably not more than 20, more preferably not more than 12, most preferably not more than 6 and especially not more 3 hours ago.

The diluent G is selected from the group consisting 25 of water, a mixture of water with one or more soluble in water in organic solvent or a mixture of water with one or more simple or honest polyfunctional alcohols, such as methanol and glycerin. The alcohols preferably bear 1, 2 or 3 hydroxy groups and 30 have preferably between 1 to 10, in particular up to 4 carbon atoms. Preference is given to primary and secondary alcohols.

Preferred alcohols are methanol, ethanol, isopropanol, ethylene glycol, 1, 2-propanediol or 1, 3-propanediol. 35 d) If necessary, the reaction mixture may be decolorized, for example by treatment with activated carbon or metal oxides, such as alumina, silica, magnesium oxide, zirconium oxide, boron oxide or mixtures thereof, in amounts of for example 0.1 -

40 50% by weight, preferably 0.5 to 25% by weight, particularly preferably 1 - 10% by weight at temperatures of for example 10 to 100 ° C, preferably 20 to 80 ° C and particularly preferably 30 to 60 ° C are subjected.

45 This can be prepared by adding the powder or granular decolorizing agent to the reaction mixture and subsequent filtration or by passing the reaction mixture through a bed the discoloring take the form of any desired suitable moldings.

The discoloration of the reaction mixture can be at any point in the workup process, for example, distance to the stage of the crude reaction mixture or after any prewash, neutralization, wash or Lösungsmittelent-.

The reaction mixture may further be subjected to a prewash e) and / or a neutralization f) and / or a subsequent wash g), preferably merely to a neutralization f). Optionally can be interchanged neutralization f) and prewash e) in order also.

From the aqueous phase of the washes e) and g) and / or neutralization f) can carboxylic acid contained B, for example, (meth) acrylic acid and / or catalyst C at least partially wiedergewon- NEN by acidification and extraction with a solvent and be used again.

For preliminary or subsequent wash e) or g) the reaction mixture is treated in a scrubber with a wash liquid, for example water or a 5-30-owned% by weight, preferably 5-20, more preferably 5 - 15% strength by weight sodium chloride, potassium chloride -, ammonium chloride, sodium sulfate or ammonium sulfate solution, preferably water or saline treated.

The ratio of reaction mixture to wash liquor is generally from 1: 0,1 - 1, preferably 1: 0,2 - 0,8, more preferably from 1: 0.3 to 0.7.

The wash or neutralization can be for example in a stirred vessel or in other conventional apparatus, for example in a column or mixer-settler apparatus performed.

Technically all known Extraktionsund washing method and apparatus can be used for washing or neutralization in the process of the invention, for example those which, 6th ed, 1999 Electronic Release, Chapter in Ullmann's Encyclopedia of Industrial Chemistry: Liquid - Liquid Extraction - Apparatus described, are. For example, these can be single or multistage, preferably single-stage, extractions and those in cocurrent or countercurrent mode, preferably be countercurrent mode. Preferably sieve tray or randomly packed columns, stirred vessels or mixer-settler apparatuses and also pulsed columns or columns are having rotating internals.

The prewash e) is preferably used when metal salts, preferably copper or copper salts are (with) used as inhibitors.

A subsequent wash g) may be the removal of base or salt traces from the neutralized in f) the reaction mixture is advantageous.

For the neutralization f) can optionally pre-washed reaction mixture containing small amounts of catalyst and the main amount of excess carboxylic acid, for example,

(Meth) acrylic acid may contain, with a 5-25, preferably 5-20, more preferably 5 - 15% by weight aqueous solution of a base, such as alkali or alkaline earth metal oxides, hydroxides -hy-, carbonates or bicarbonates, preferably caustic soda, potassium hydroxide, sodium bicarbonate, sodium carbonate, potassium, Kaiziumhydroxid, lime, ammonia, ammonia water or potassium carbonate, optionally 5 - may be 15 wt% sodium chloride, potassium chloride, ammonium chloride or ammonium sulfate is added, more preferably with sodium hydroxide or sodium hydroxide-salt solution are neutralized. The degree of neutralization preferably is 10 to 80 mol%, preferably 20 to 80 mol%, particularly preferably 40 to 80 mol%, based on the acid group-containing monomers. This neutralization can take place before and / or during the polymerization, preferably before the polymerization.

The addition of the base is carried out in such a manner that the temperature did not rise above 60 ° C in the apparatus, preferably between 20 and 35 ° C and the pH of 4-13 is. The dissipation of the neutralization heat is preferably carried out by cooling the vessel with the aid of internal cooling coils or via jacketed cooling.

The ratio of reaction mixture: Neutralisationsflüssig- speed is usually 1: 0,1 - 1, preferably 1: 0,2 - 0,8, more preferably from 1: 0.3 to 0.7.

With regard to the apparatus, the above statements.

h) If a solvent is present in the reaction mixture, so it can be removed by distillation substantially. Preferably, any solvent present is by weighing see and / or neutralization removed from the reaction mixture, if desired, this can also take place prior to the wash or neutralization.

For this purpose the reaction mixture with an amount is to

Storage stabilizer, preferably hydroquinone added that after removal of the solvent 100 - 500, preferably 200-500 and more preferably 200-400 ppm thereof (residue) are included in the target ester.

The distillative removal of the main amount of solvent is effected for example in a stirred tank with jacketed heating and / or internal heating coils under reduced pressure, for example at 20-700 mbar, preferably 30 to 500 and more preferably 50-150 mbar and a temperature 40-80 ° C. Of course, that the distillation in a falling film or thin film evaporator. For this, the reaction mixture, preferably several times in the cycle, under reduced pressure, for example at 20 - 700 mbar, preferably 30 to 500 and more preferably 50 - -80 ° C through the apparatus - 150 mbar and a temperature of 40th

An inert gas, preferably an oxygen-containing gas, more preferably air or a mixture of air and nitrogen (air) are introduced into the distillation apparatus, for example, 0.1 - 1. preferably 0,2 - 0,8, and more preferably 0, 3 to 0.7 m 3 / m 3 h, based on the volume of the reaction mixture.

The residual solvent content in the residue after

Distillation is generally below 5% by weight, preferably 0.5 to 5% and more preferably 1 to 3 wt%.

The removed solvent is condensed and preferably reused.

If necessary may be performed in addition to or instead of the distillation, a solvent i).

For this, the target ester, which still contains small amounts of solvent, at 50 - 90 ° C, preferably 80 - heated to 90 ° C and the remaining amounts of solvent removed with a suitable gas in a suitable Aparatur. To support can optionally also be a vacuum. Suitable apparatuses are, for example, columns of per se known type which, preferably have the customary internals, for example trays, dumped packing or structured packing beds. Useful column internals include in principle all common internals, for example trays, structured packings and / or random packing. Among the trays cap trays, sieve trays, valve trays, Thormann trays and / or dual-flow trays are preferred; among the dumped packings are those of rings, coils, saddles, Raschig, Intos or Pall rings, barrel or Intalox saddles, Top-Pak, etc. or braids.

Another possibility here is a falling-film, thin-film or wiped film evaporator, such as a Luwa, Rotafilm or Sambay evaporator, which may be splash-protection, for example with a demister.

Suitable gases are inert under the stripping gases, preferably oxygen-containing gases, more preferably air or mixtures of air and nitrogen (lean air) or water vapor, in particular those which are heated to 50 to 100 ° C.

The stripping gas is, for example, 5-20, particularly preferably 10 - 20 and very particularly preferably 10 to 15 m3 / m3h, based on the volume of the reaction mixture.

If necessary, the ester at any stage of the workup process, preferably after washing / neutralization and any effected solvent removal filtration j) are subjected to remove precipitated traces of salts and, where appropriate decolorizing.

In one conceivable embodiment, the esterification a) A of the polyalcohol with the carboxylic acid B in an above-mentioned molar excess of at least 5: 1 in the presence of at least one esterification catalyst C and of at least one

Polymerization inhibitor D performed without forms an azeotrope with water.

The carboxylic acid B used in excess is not removed in a preferred embodiment, essentially, that it is only the proportion of carboxylic acid B is removed from the reaction mixture, which is determined by the volatility at the employed temperature, and are also no measures for separation the carboxylic acid carried out as for example by distillation, rectification, extractive, such as washes, absorptive, such as being passed over activated carbon or ion exchanger, and / or chemical steps such as interception of the carboxylic acid with epoxides.

Preferably, the carboxylic acid B contained in the reaction mixture is not more than 75% by weight, particularly preferably not more than 50% by weight, very particularly preferably to not more than 25% by weight, especially not more than 10%, and especially not more than 5% by weight from the reaction mixture separated off, based on the contained end of the reaction in the reaction mixture the carboxylic acid B. in a particularly preferred embodiment can be dispensed with the step b), so that only the amount of water of reaction and the carboxylic acid B is removed from the reaction mixture, which is determined by the volatility at the employed temperature. This can preferably be prevented by substantially complete condensation.

Furthermore, the esterification catalyst C used remains substantially in the reaction mixture.

The reaction mixture thus obtainable preferably has an acid value gem. DIN EN 3682 of at least 25 mg KOH / g of reaction mixture, particularly preferably from 25 to 80 and very particularly preferably from 25 to 50 mg KOH / g.

On a preliminary or subsequent wash e) or g) is preferably omitted; merely a filtration step j) may be useful.

Then the reaction mixture in step c) can be diluted, in this case, it is preferably implemented within 6 hours, more preferably within 3 hours to form the hydrogel. Preferably it can be neutralized in a step f).

The sequence of steps c), j) and f) is arbitrary.

The invention also relates to a composition of matter comprising

- At least one ester F obtainable by one of the esterification processes described above,

- Carboxylic acid B and - diluent G.

Further components may be included

- Esterification catalyst C in protonated or unprotonated form, - polymerization inhibitor D and - Optionally solvent E if such was used in the past padding is.

The mixture may optionally be neutralized and have a pH as listed above under f).

When the mixture is neutralized, so some of the carboxylic acids B is at least converted into their water-soluble alkali metal, alkaline earth metal or ammonium salts.

Preferred mixture contains at

- Ester F in a fraction from 0.1 to 40 wt .-%, particularly preferably 0.5 to 20, very particularly preferably 1 to 10, especially 2 to 5 and especially from 2 to 4 wt .-%, - carboxylic acid 0.5 B - 99.9% by weight, particularly preferably 0.5 - 50% by weight, very particularly preferably 1 - 25, in particular 2 - 15 and especially 3 to 5% by weight,

- Esterification catalyst C 0 - 10 wt%, particularly preferably 0.02

- 5, very particularly preferably 0.05 - 2.5% by weight and in particular 0.1 - 1% by weight,

- Polymerization inhibitor D 0-5% by weight, particularly preferably 0.01

- 1.0, very particularly preferably 0.02 to 0.75, in particular 0.05 - 0.5 and especially from 0.075 to 0.25% by weight,

- E solvent 0 - 10% by weight, more preferably 0 - 5% by weight, very particularly preferably 0.05 - 1.5% by weight and in particular 0.1 -

0.5% by weight, with the proviso that the sum is always 100% by weight, and

- Any diluent G ad 100% by weight.

The reaction mixtures obtainable by the above methods and compositions of the invention may be used

- As radical of water-absorbing hydrogels,

- As starting material for the preparation of polymer dispersions,

- As a raw material for producing polyacrylates (apart from hydrogels),

- As Lackrohstoff or

- As a cement additive.

For use as a free-radical crosslinker of water-absorbing hydrogels, such compositions of the invention are particularly suitable have a water solubility (at 25 ° C in distilled water) of at least 5% by weight, preferably at least 10% by weight, more preferably at least 20% by weight, very particularly preferably at least 30 % by weight and especially of at least 50% by weight. k) The reaction mixture from the esterification, including workup steps, so far as these are passed through, for example, the reaction mixture from f), respectively, if they are not f), from b), or, if they are not b), the reaction mixture from a ), may optionally be added with additional monoethylenically unsaturated compounds N which do not bear an acid group but are copolymerizable with the hydrophilic monomers M, then can be polymerized at least one radical initiator K and optionally at least one grafting base L for the production of water-absorbing hydrogels in the presence ,

Advantageously

1) the reaction mixture from k) postcrosslinked.

For preparing k) hydrophilic this, superabsorbent hydrogels suitable hydrophilic monomers M are, for example, polymerizable acids such as acrylic acid, methacrylic acid, ethacrylic acid, α-chloro acrylic acid, maleic acid, maleic anhydride, vinyl sulfonic acid, vinylphosphonic acid, maleic acid including its anhydride, fumaric acid, citraconic acid, mesaconic acid, glutaconic acid, aconitic acid, allyl sulfonic acid, sulfoethyl acrylate, Sulfomethacrylat, Sulfopropyla- methacrylate, sulfopropyl methacrylate, 2-hydroxy-3-acryloxypropylsulfon- acid, 2-hydroxy-3-methacryl-oxypropylsulfonsäure, Allylphosphon- acid, styrenesulfonic acid, 2-acrylamido 2methylpropansulfonsäure, 2-acrylamido-2-methylpropane and also their amides, hydroxyalkyl esters and amino- or ammonio-containing esters and amides. The monomers can be used alone or mixed among each other. Furthermore water-soluble N-vinyl nylamide or else diallyldimethylammonium chloride. Preferred hydrophilic monomers are compounds of the formula V

<img id="imgf000035_0001" he="20" wi="23" file="imgf000035_0001.tif" img-format="tif" img-content="drawing" orientation="portrait" inline="no" />

wherein

R³ Hydrogen, methyl or ethyl,

R⁴ the group -COOR⁶, A sulfonyl or phosphonyl group, an esterified with a (-C ~ C) alkyl alcohol phosphonyl or a group of formula VI <img id="imgf000036_0001" he="14" wi="34" file="imgf000036_0001.tif" img-format="tif" img-content="drawing" orientation="portrait" inline="no" /> H H-

R⁵ Hydrogen, methyl, ethyl or carboxyl,

R⁶ Hydrogen, amino or hydroxy- (Cχ-C) -alkyl and

R⁷ a sulfonyl group, a phosphonyl group or a carboxyl group.

Examples of (C₁-C₄) - Alkyl alcohol are methanol, ethanol, n-propanol or n-butanol.

Particularly preferred hydrophilic monomers are acrylic acid and methacrylic acid.

To optimize properties, it may be sensible to use additional monoethylenically unsaturated compounds N which do not bear an acid group but are copolymerizable with the monomers bearing acid groups. These include nitrile, for example, the amides and nitriles of monoethylenically unsaturated carboxylic acid, eg. As acrylamide, methacrylamide and N-vinylformamide, N-vinyl nylacetamid, N-methyl-vinylacetamide, acrylonitrile and methacrylonitrile. Other suitable compounds are, for example, vinyl esters of saturated -C ~ -C₄Carboxylic acids such as Vinylfor iat, vinyl acetate or vinyl propionate, alkyl vinyl ethers with at least 2 C-atoms in the alkyl group such as. For example, ethyl vinyl ether or butyl vinyl ether, esters of monoethylenically unsaturated C₃-. To Cg-carboxylic acids, such as esters, of monohydric Ci- to Cis alcohols and acrylic acid, methacrylic acid or maleic acid, monoesters of maleic acid, such as methyl hydrogen maleate, N-Vinyllactarne such as N-vinylpyrrolidone or N-vinylcaprolactam. monovalent acrylic and methacrylic esters of alkoxylated monohydric saturated alcohols, for. example of alcohols having 10 to 25 carbon atoms which have been reacted with 2 to 200 mol ethylene oxide and / or propylene oxide per mole of alcohol, as well as mono-acrylic acid esters and Monomethacryl- esters of polyethylene glycol or polypropylene glycol, the molar masses (M_n) Of the polyalkylene glycols, for example, to be able to 2000th Further suitable monomers are styrene and alkyl-substituted styrenes, such as ethylstyrene and tert-butylstyrene.

This without acid groups monomers can be used in a mixture with other monomers, eg. B.

Mixtures of vinyl acetate and 2-hydroxyethyl acrylate in any proportion. This no monomers bearing acid groups are to the reaction mixture in quantities of between 0 and 50 wt .-%, preferably less than 20 wt .-% was added.

Preferably, the cross-linked (co) polymers of acid-group-containing monoethylenically unsaturated monomers, which are optionally converted before or after the polymerization in their alkali or ammonium salts, and from 0 - 40 wt .-%, based on its total weight no acid-functional monoethylenically unsaturated monomers.

The manufacturing (meth) acrylic acid (co) polymers, polyacrylic acids and superabsorbents has been extensively described and therefore is well known, see for example "Modern Superabsorbent Polymer Technology", FL Buchholz and AT Graham, Wiley-VCH., 1998

Preferred hydrogels which are obtained by crosslinking polymerization or copolymerization of acid-functional monoethylenically unsaturated monomers M or salts thereof.

In the method for post-crosslinking the starting polymer is treated with a postcrosslinker and, preferably, post-crosslinked during or after the treatment by raising the temperature, and dried, wherein the crosslinker preferably in an inert solvent is contained. U nder inert solvents are understood to be those which react in the reaction either with the starting polymer or with the postcrosslinker. Preferred are such solvents, of which more than 90%, preferably more than 95%, particularly preferably more than 99%, in particular more than 99.5% do not react chemically with the starting polymer or postcrosslinkers.

Postcrosslinking 1) and drying m) where the temperature range between 30 and 250 ° C, particularly 50 - 200 ° C, most preferably the range between 100 - 180 ° C. The surface postcrosslinking solution is preferably applied by spraying the polymer in suitable spray mixers. Following spraying, the polymer powder is thermally dried, and the crosslinking reaction can take place either before or during the drying. Preference is given to spraying a solution of the crosslinker in reaction mixers or mixing and drying systems such as Lödige mixers, BEPEX mixers, NAUTA mixers, SHUGGI mixer or PROCESSING SALL. Moreover, fluidized bed dryers can be used. Drying may take place in the mixer itself, by heating the jacket or blowing in warm air. Equally suitable is a downstream dryer such as a tray dryer, a rotary kiln, or a heatable screw. But it may also be eg as a drying process azeotropic distillation. The preferred residence time at this temperature in the reaction mixer or dryer is below 60 min. , More preferably below 30 min.

Preferably the above processes wherein the starting polymer is a polymeric acrylic acid or a polyacrylate, especially a polymeric acrylic acid or a polyacrylate obtained by free-radical polymerization and where a mehrfunktio- was used tional ethylenically unsaturated radical are.

such methods are preferred in which the composition of matter containing radical crosslinkers, ie the ester F, and diluents G in a ratio of 0.1 - 10 wt .-% used based on the mass of the starting polymer - 20 wt .-%, in particular 0.5 becomes.

Such processes are preferred in which the free-radical in a dose of 0.01 -. 5.0% by weight, preferably 0.02 - 3.0 wt%, most preferably 0.03 -.. 2.5% by weight, in particular 1.0 is used, and especially 0.1 to 0.75% by weight based on the starting polymer - 0.05..

The invention also provides polymers prepared according to any one of the above method and their use in hygiene articles, packaging materials and nonwovens, as well as the use of an abovementioned composition of matter for the preparation of crosslinked or crosslinkable by heat treating polymers, in particular in paints and coatings.

The case to be used hydrophilic, highly swellable hydrogels (starting polymers) are in particular polymers of (co) polymerised hydrophilic monomers M, graft (co) polymers of one or more hydrophilic monomers M on a suitable grafting base L, crosslinked starch ethers or swellable in aqueous liquids natural products, for example guar derivatives. These hydrogels are known to the expert and described for example in US-4,286,082, DE-C-27 06 135, US 4,340,706, DE-C-37 13 601, DE-C-28 40 010, DE-A- 43 44 548, DE-A40 20 780, DE-A-40 15 085, DE-A-39 17 846, DE-A-38 07 289, DE-A-35 33 337, DE-A-35 03 458, DE-A-42 44 548, DE-A-42 19 607, DE-A-40 21 847, DE-A-38 31 261, DE-A-35 11 086. DE-A-31 18 172, DE- A-30 28 043, DE-A-44 18 881, EP-A-0801483, EP-A-0455985, EP-A-0467073, EP-A-0312952, EP-A-0205874 , EP-A-0499774, DE-A 26 12 846, DE-A-40 20 780, EP-A-0 20 5674, US-5,145,906, EP-A-0530438, EP-A-0 670 073, US4 057 521, US 4,062,817, US 4,525,527, US 4,295,987, US 5,011,892, US 4,076,663 or US 4 931 497. particularly suitable are also highly swellable hydrogels describes a manufacturing process as described in WO 01/38402, and described inorganic-organic hybrid highly swellable hydrogels as described in DE 198 54 575th The contents of the aforementioned patent documents, in particular, the hydrogels prepared by the process, are expressly part of the present disclosure.

Suitable graft L for hydrophilic hydrogels, which are obtainable by graft copolymerization of olefinically unsaturated acids may be of natural or synthetic origin. Examples are starch, cellulose or cellulose derivatives and also other polysaccharides and oligosaccharides, polyalkylene oxides, especially polyethylene oxides and polypropylene oxides, and also hydrophilic polyesters.

The water-absorbing polymer can be obtained via radikalisehe graft of acrylic acid or acrylate onto a water-soluble polymer matrix. Suitable water-soluble polymer lymermatrices are, for example, but not limited to, alginates, polyvinyl alcohol and polysaccharides such as starch. Graft copolymerization for the purposes of the invention, a polyfunctional ethylenically unsaturated radical crosslinker.

The water-absorbing polymer may be other, an organic-inorganic hybrid polymer formed from a polymeric acrylic acid or polyacrylate on the one hand and a silicate, aluminate or aluminosilicate. In particular, polymeric acrylic acid or polyacrylate used may be obtained by free-radical polymerization and where a polyfunctional ethylenically unsaturated radical crosslinker and in which manufacturing process a water-soluble silicate or soluble aluminate or mixture has been used by both.

Preferred hydrogels are in particular polyacrylates, polymethacrylate acrylates and graft polymers described in US 4,931,497, US 5,011,892 and US 5,041,496. Very particularly preferred hydrogels are the kneader described in WO 01/38402 and those described in DE 198 545 75 hybrid organic-inorganic hydrogels based on polyacrylates. The inventively prepared, are useful as radical in hydrogels, can be used alone or in combination with postcrosslinkers other crosslinkers, for example internal or surface, such as the following:

Particularly suitable crosslinkers are methylenebisacrylamide or -. Methacrylamide, esters of unsaturated mono- or polycarboxylic acids of polyols, such as diacrylate or triacrylate, for example butanediol or ethylene glycol acrylate or methacrylate and trimethylolpropane triacrylate and AIlylVerbindungen as allyl (meth) acrylate, triallyl maleate, polyallyl esters, Te traallyloxyethan, triallylamine, tetraallylethylenediamine, allyl esters of phosphoric acid and also vinylphosphonic acid derivatives as described for example in EP-A-0 343 427th but are particularly preferred in the process according to hydrogels prepared using polyallyl ethers as crosslinkers and by acidic homopolymerization of acrylic acid. Suitable crosslinkers are pentaerythritol tetraallyl, polyethylene glycol diallyl ether, monoethylene glycol diallyl ether, Glyceroldi- and triallyl ether, polyallyl ethers based on sorbitol, and also ethoxylated variants thereof. Particularly preferred crosslinkers are polyethylene glycol diacrylates, ethoxylated derivatives of trimethylolpropane for example Sartomer SR 9035, and also ethoxylated derivatives of glycerol and glycerol. Of course, mixtures of the above crosslinkers.

Very particular preference is given to hydrogels provides are with an inventively prepared esters F as radical produced.

The water-absorbing polymer is preferably a polymeric acrylic acid or a polyacrylate. This water-absorbing polymer can be for a known th from the literature. Preference is given to polymers which comprise crosslinking comonomers (0.001 to 10 mol%), very particular preference is given to polymers obtained by radical polymerization using a polyfunctional ethylenically unsaturated radical crosslinker.

The hydrophilic, highly swellable hydrogels can be prepared by per se known polymerization process. Preference is given to polymerization in aqueous solution by the process known as gel polymerization. In this case, be diluted as mentioned above, preferably aqueous, more preferably 15 to 50

Wt .-% aqueous solutions of one or more hydrophilic mono-mer, and optionally a suitable grafting base L in The presence of a radical initiator, preferably without mechanical mixing, utilizing the Trommsdorff Norrish effect (Makromol. Chem. 1, 169 (1947)), polymerized. The polymerization reaction can in the temperature range between 0 ° C and 150 ° C, preferably be carried out between 10 ° C and 100 ° C, not only at atmospheric pressure but also at elevated or reduced pressure. As is customary, the polymerization can also in a protective gas atmosphere, preferably under nitrogen, are executed. To initiate the polymerization-energy electromagnetic can see rays or the customary chemical polymerization initiators K are used, z. B. organic peroxides such as benzoyl peroxide, tert. Butyl hydroperoxide, cumene hydroperoxide, azo compounds such as azodiisobutyronitrile and also inorganic peroxo compounds such as (NH)₂S₂0s. KS₂0s or H0₂,

You can, optionally in combination with reducing agents such as ascorbic acid, sodium bisulfite, and iron (11) - sulfate or redox systems containing as reducing component an aliphatic or aromatic sulfinic acid, such Benzolsulfin- acid and toluene sulfinic acid or derivatives thereof, such as. are Mannich adducts of sulfinic acids, aldehydes and amino compounds, as are described in DE-C-1301566 used. By subsequently heating the polymer gels at 50 ° to 130 ° C, preferably 70 ° to 100 ° C, the quality properties of the polymers can be further improved.

The gels obtained are to 0 - 100 mol%, preferably to 25 - 100 mol%, and most preferably 50 - 85 mol% neutralized, based on monomer used, for which the customary neutralizing agents can be used, preferably alkali metal hydroxides, alkali metal oxides or the corresponding alkali metal carbonates, particularly preferably sodium hydroxide, sodium carbonate and sodium bicarbonate.

Typically, the neutralization by mixing in the neutralizing agent as an aqueous solution or else preferably as a solid. The gel is mechanically comminuted, for example by means of a meat grinder, and the neutralizing agent is sprayed, sprinkled or poured on and then carefully mixed in. The gel mass obtained can be repeatedly minced for homogenization. The neutralized gel mass is then dried until the residual moisture content is preferably below 10 wt .-%, in particular less than 5 with a belt or drum dryer wt .-%. The polymerization as such can also be carried out by any other process described in the literature. In particular, the neutralization of the acrylic acid can also be carried out prior to polymerization) described above in step f. The polymerization can then be carried out continuously or discontinuously in a known to the expert belt reactor or a kneading reactor. In carrying out the polymerization in a belt reactor, initiation by electromagnetic radiation, preferably by UV radiation, or alternatively, the initiation with a redox initiator is especially preferred. Most preferably, the combination of two methods of initiation: electromagnetic radiation and chemical redox initiator system simultaneously.

n) The dried hydrogel can then be ground and sieved, typically including roll mills, pin mills or swing mills for the grinding. The preferred particle size of the sieved hydrogel is preferably in the range 45 - 1000 .mu.m, preferably 45-850 .mu.m, more preferably 200-850 microns, and most preferably at 300-850 microns. These ranges preferably 80 wt .-% of the particles, in particular 90 wt .-% of the particles. The size distribution can be determined using established laser methods.

The present invention further provides crosslinked hydrogels, which are contained and crosslinked at least one hydrophilic monomer M in copolymerized form merisierter shape with an ester F of a polyhydric alcohol A having at least one ethylenically unsaturated carboxylic acid B. The ester may according to the invention or a prior art be prepared conventionally, preferably the inventive manner.

As the ester F include compounds, as described above. Polyalcohols A and ethylenically unsaturated carboxylic acids B are also those as described above.

Preference is given to esters F as those used in which the polyalcohol A is selected from the list polyol which as additional functionality at least one ether, carboxyl or C - C₄having -Alkyloxycarbonylfunktion, sugar alcohols, partially alkoxylated sugar alcohols, polyester polyols, at least partially alkoxylated polyesterols and at least partially hydrolyzed, alkoxylated polyesterols, as described above, respectively. Particularly preferred are those esters F, in which the polyol A is selected from the acid ditrimethylolpropane, dipentaerythritol, dimethylolpropionic acid and Dimethylolbutter- list.

Other preferred esters F are those of the formula VII, as defined above, in which Y is independently

- For x = 2 is a number greater than 8, preferably more than 10, more preferably more than 12 and especially at least 15 and - when x = 3 or greater a number greater than 7, preferably more than

9, particularly preferably greater than 12 and in particular at least 15.

Also preferred are esters F of the formula VII, define as above defined, where y independently of one another up to 6, particularly preferably up to 4, and most preferably the fourth

Also useful are esters F of the formula VII, as defined above, can take in which y = 2 for x values ​​of 0, 1 or 2 and x = 3 for y values ​​of 0 or the first

The polyhydric alcohols described by the formula VII A in the esters F, which are used as crosslinkers in the hydrogels mentioned above may, in each case ethoxylated, propoxylated or ethoxylated and propoxylated, and mixed ethoxylated be in particular exclusively, ie R¹⁰ in formula VII can mean, for example, independently of one another hydrogen and / or methyl and in particular hydrogen exclusively.

Particularly preferred esters F of the formula VII, such esters F of a polyhydric alcohol A having at least one ethylenically unsaturated carboxylic acid B, wherein it is in the polyol A is a per glycerol three to four times ethoxylated glycerol or a per hydroxy four tuply ethoxylated trimethylolpropane or pentaerythritol ,

The CRC value [g / g] of the hydrogel-forming polymers of the invention can by the methods indicated in the description can be measured and is preferably above 15, especially 16, 18, 20, 22, 24, or higher, more preferably 25, in particular at 26, 27, 28, 29, in particular preferably at 30, 31, 32, 33, 34, 35, 36, 37 or higher.

The AUL 0, 7psi value [g / g] of the hydrogel formen invention the polymers can by the methods indicated in the description can be measured and is preferably above 8, especially 9,

10, 11, 12, 13, 14 or higher, particularly preferably at 15 par- in particular 16, 17, 18, 19, or higher, particularly preferably greater than 20, in particular 21, 22, 23, 24, 25, 26, 27, 28, or higher.

The AUL 0, 5 psi value [g / g] of the hydrogel formen invention the polymers can by the methods indicated in the description can be measured and is preferably above 8, especially 9, 10, 11, 12, 13, 14 or higher, especially preferably 15, in particular at 16, 17, 18, 19, or higher, particularly preferably greater than 20, in particular 21, 22, 23, 24, 25, 26, 27, 28, or higher.

Application and use of hydrogel-forming polymers of the invention

The present invention further relates to the use of the above hydrogel-forming polymers in hygiene articles comprising

(P) an upper liquid-permeable cover

(Q) a fluid-impervious backsheet

(R) a core positioned between (P) and (Q) and comprising

10-100 wt .-% of the hydrogel-forming polymer lymer

0 - 90 wt .-% of hydrophilic fiber material preferably 20-100 wt .-% of the inventive hydrogel forming polymer, 0-80 wt .-% of hydrophilic fiber material more preferably 30-100 wt .-% of the hydrogel-forming polymer, 0 - 70 wt .-% of hydrophilic fiber material even more preferably 40 - 100 weight .-% of the hydrogel-forming polymer, 0 - 60 wt .-% of hydrophilic fiber material more preferably 50 - 100 weight .-% of the inventive

Hydrogel-forming polymer 0-50 wt .-% hydrophilic

Fiber material particularly preferably 60-100 wt .-% of the hydrogel-forming polymer, 0 - 40 wt .-% hydrophilic

Fiber material especially preferably 70-100 wt .-% of the hydrogel-forming polymer, 0-30 wt .-% of hydrophilic fiber material extremely preferably 80-100 wt .-% of the hydrogel-forming polymer, 0-20 wt .-% hydrophilic fibrous material most preferably 90-100 wt .-% of the hydrogel-forming polymer, 0 - 10 wt .-% of hydrophilic fiber material

5 (S) optionally one positioned directly above and below the core (R) to tissue layer and (T) optionally an acquisition layer positioned between (P) and (R) is exploiting dividend up.

10 The percentages are to be understood as meaning that at 10-100% by weight, 11, 12, 13, 14, 15, 16, 17, 18, 19 to each 100 wt .-% of the hydrogel-forming polymer and everyone in between. - liegendnen% data (eg 12.2%) are possible and correspondingly hydrophilic fiber material from 0 to respectively 89, 88, 87, 86, 85,

15 83, 82, 81 wt .-% and in between percentages (for example 87.8%) are possible. When further materials in the core, decrease accordingly the percentages of polymer and fiber. The ananloge applies to the preferred ranges, for example in extremely preferably 81, 82, 83, 84, 85, 86, 87,

20 88, 89 wt.% For the inventive hydrogel-forming polymer and are present in accordance with 19, 18, 17, 16, 15, 14, 13, 12, 11% by weight of the fiber material. So the preferred range 20, 21, 22, 23, 24, 25, 26, 27, 28, 29 to 100 wt .-% inventive hydrogel forming polymer, the more preferred range 30, 31,

25 32, 33, 34, 35, 36, 37, 38, 39 to 100 wt .-% according to the invention hydrogel-forming polymer, in the more preferred range, 40, 41, 42, 43, 44, 45, 46, 47, 48 , 49 to 100 wt .-% inventive hydrogel forming polymer, the invention in the more preferred range 50, 51, 52, 53, 54, 55, 56, 57, 58, 59 to 100 wt .-%

30 invention hydrogel-forming polymer in the particularly preferred range 60, 61, 62, 63, 64, 65, 66, 67, 68, 69 to 100 wt .-% inventive hydrogel forming polymer, in particular preferred range 70, 71, 71, 72, 73, 74, 75, 76, 77, 78, 79 to 100 wt .-% inventive hydrogel forming polymer, and in the

35 most preferred range 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 or 100 wt .-% present invention hydrogel-forming polymer.

Hygiene articles are to be understood not only incontinence pads and incontinence briefs 40 for adults but also diapers for babies.

In the liquid-permeable cover (P) is the layer which has direct contact with skin. Its material for 5 consists of customary synthetic or semisynthetic fibers or films of polyesters, polyolefins, rayon or natural fibers such as cotton. For non-woven materials the fibers are to be connected as a rule by binders such as polyacrylates. Preferred materials are polyesters, rayon and blends thereof, polyethylene and polypropylene. Examples of liquid-pervious layers are described in WO 99/57355 5 AI, EP 102 388 A2 3.

The liquid-impervious layer (Q) is generally a sheet of polyethylene or polypropylene.

10 The core (R) includes not only the hydrogel-forming polymer according to the invention of hydrophilic fiber material. By hydrophilic is meant that aqueous fluids spread quickly over the fiber. Usually, the fibrous material is cellulose, modified cellulose, rayon, polyesters such as polyethylene terephthalate.

15 Particularly preferred cellulose fibers such as pulp. The fibers typically have a diameter 1-200 microns, preferably 10-100 microns. Moreover, the fibers have a minimum length of 1 mm.

20 The structure and the shape of diapers is generally known and, for example, in WO 95/26 209 page 66 line 34 to page 69 line 11, DE 196 04 601 AI, EP-A-0316518 and EP-A- 0,202,127 described. Generally, nappies and other sanitary products also in WO 00/65084, especially at pages 6-15, WO 00/65348,

25 in particular, pages 4 - 17, WO 00/35502, particularly pages 3-9, DE 19737434, WO 98/8439 describes. Hygiene articles for feminine hygiene are described in the following references. The aqueous fluids of absorbing hydrogel-forming polymers can be used there. Literature-

30 make feminine hygiene: WO 95/24173: Absorption Article for Controlling Odour, WO 91/11977: Body Fluid Odour Control, EP 389023: Absorbent Sanitary Articles, WO 94/25077: Odour Control Material, WO 97/01317: Absorbent Hygienic Article, WO 99/18905, EP 834 297, US 5,762,644, US 5,895,381, WO 98/57609, WO

35 2000/065083, WO 2000/069485, WO 2000/069484, WO 2000/069481, US 6,123,693, EP 1104666, WO 2001/024755, WO 2001/000115, EP 105373, WO 2001/041692, EP 1074233. Tampons are in following headings described: WO 98/48753, WO 98/41179, WO 97/09022, WO 98/46182, WO 98/46181, WO 2001/043679, WO 2001/043680, WO 2000/061052, EP

40 1108408, WO 2001/033962, DE 200020662, WO 2001/001910, WO

2001/001908, WO 2001/001909, WO 2001/001906, WO 2001/001905, WO 2001/24729. Incontinence products are described in the following publications: Disposable Absorbent Article for Incontinent Individuais: EP 311344 Description P. 3 - 9; Disposable Absorbent Ar-

45 ticle: EP 850 623; Absorbent Article: WO 95/26207; Absorbent Article: EP 894 502; Dry Laid Fibrous Structure: EP 850 616; WO 98/22063; WO 97/49365; EP 903 134; EP 887 060; EP 887 059; EP 887058; EP 887 057; EP 887 056; EP 931 530; WO 99/25284; WO 98/48753. Feminine care and incontinence articles are described in the following references: Catamenial Device: WO 93/22998 description P. 26 - 33; Absorbent Members for Body Fluids: WO 95/26209 description P. 36 - 69; Disposable Absorbent Article: WO

98/20916 Description P. 13 - 24; Improved Composite Absorbent Structures: EP 306262 Description P. 3 - 14; Body Waste Absorbent Article: WO 99/45973. These references and the references therein are hereby expressly incorporated into the disclosure of the invention fertil.

The hydrogel-forming polymers of the invention are very useful as absorbents for water and aqueous liquids, so that they can advantageously be used as a water retainer in market gardening, as a filter aid and particularly as an absorbent component in hygiene articles such as diapers, tampons or sanitary napkins.

Incorporation and Fixation of the highly swellable hydrogels according to the invention

In addition to the above-described highly swellable hydrogels, the absorbent composition of the present invention compositions before, which include highly swellable hydrogels or to which they are fixed. Any construction is suitable that is capable of accommodating highly swellable hydrogels and can also be integrated into the absorption layer. A variety of such compositions is already known and described in detail in the literature. A construction for installing the highly swellable hydrogels can be for. Example a fiber matrix consisting of a cellulose fiber mixture (air- laid web, wet laid web) or of synthetic polymer fibers (meltblown web, spunbonded web), or of a mixed-fiber factory from cellulose fibers and synthetic fibers. Possible before fiber materials are described in detail in subsequent chapters. The process of an air-laid web, for example, can in WO 98/28 478. Furthermore, open-celled foams are used, or the like to install highly swellable hydrogels.

Alternatively, the result of fusing two individual layers, such a construction in which one or better a multiplicity of chambers which contain the highly swellable hydrogels. Such a chamber system is geschil- detail changed in EP 0615736 AI S. 7 line 26 ff. In this case, at least one of the two layers should be water pervious. The second layer may either be water pervious or water impervious. The layer material can Tissues or other fabric, closed or open-pored foams, perforated films, elastomers or fabrics composed of fiber material. When the absorbent composition consists of a construction of layers, the layer material should have a pore structure whose pore dimensions are small enough to retain the highly swellable hydrogel gel particles. The above examples of construction of the absorbent composition also include laminates of at least two layers with a between which the highly swellable hydrogels are installed and fixed.

Generally it is possible, hydrogel particles within the absorbent core to improve the so-called. Dry and wet integrity to fix. Dry and wet integrity describes the ability to install highly swellable hydrogels such in the absorbent composition that they both withstand external forces in the wet and in the dry state and there are no dislocations or leakage of highly swellable polymer. The forces mainly mechanical loads are to be understood as they occur in the course of movement while wearing the hygiene article or else the weight pressure on the hygiene article in particular the case of incontinence. In order to fix it are a number of ways that are known to the expert. Examples such as fixation by heat treatment, addition of adhesives, thermoplastics, binder materials are noted in WO 95/26 209 page 37 line 36 to page 41 line 14. The cited passage is thus part of this invention. Methods for enhancing wet strength are also found in WO 2000/36216 Al.

Furthermore, the absorbent composition may comprise a carrier material, such. As a polymer film on which the highly swellable hydrogel particles are fixed. The fixation can be made both single and both sides. The carrier material may be water-pervious or water-impervious.

The above constructions of the absorbent composition incorporate the highly swellable hydrogels at a weight fraction of 10 to 100% by weight, preferably 20-100 wt .-%, more preferably 30-100 wt .-%, more preferably 40-100 wt .-%, more preferably 50-100 wt .-%, particularly preferably 60 to 100 wt .-%, particularly preferably 70 to 100 wt .-%, even more preferably 80 to 100 wt .-% and most preferably 90-100 wt .-% based on the installed total weight of the composition and the highly swellable hydrogels.

Fiber Materials of the Absorbent Composition

The structure of the present invention the absorbent composition is based on a variety of fibrous materials which are used as a fiber network or matrices. With enclosed by the present invention includes not only fibers of natural origin (modified or unmodified) but also synthetic fibers.

A detailed overview of examples of fibers which can be used in the present invention are given in WO 95/26 209 page 28 line 9 to page 36 line 8. The cited passage is thus part of this invention.

Examples of cellulose fibers include those which are customarily used in absorption products, such as fluff pulp and cellulose of the cotton type. The materials (soft- or hardwoods), production processes such as chemical pulp, semi-chemical pulp, chemi-mechanical pulp (CTMP) and bleaching processes are not particularly limited. So For example, natural cellulose fibers such as cotton, flax, silk, wool, jute, ethylcellulose and cellulose acetate are used.

Suitable synthetic fibers are made from polyvinyl chloride, polyvinyl fluoride, polytetrafluoroethylene, polyvinylidene chloride, polyacrylics such as ORLON, polyvinyl acetate, poly ethyl vinyl acetate, polyvinyl alcohol, soluble or insoluble. Examples of synthetic fibers include thermoplastic polymer lyolefinfasern such as polyethylene fibers, polyester fibers (PULPEX®) and polypropylene fibers, polyethylene-polypropylene bicomponent fibers, poly, such as polyethylene terephthalate (DACRON^® or K0 DEL®), copolyesters, polyvinyl acetate, polyethyl, polyvinyl chloride, polyvinylidene chloride, polyacrylics, polyamides, copolyamides, polystyrene and copolymers of the aforementioned polymers and also bicomponent fibers composed of polyethylene terephthalate-polyethylene isophthalate copolymer Polyethylvinyl- acetate / polypropylene, polyethylene / polyester, polypropylene / polyester, copolyester / polyester, polyamide fibers (nylon), polyurethane fibers, polystyrene fibers and polyacrylonitrile. Preferably, polyolefin fibers, polyester fibers and bicomponent fibers which are two. Further preferred in the heat are adhesive bicomponent fibers composed of polyolefin of the core-sheath type and side te-by-side type on account of their excellent dimensional stability following fluid absorption.

The synthetic fibers mentioned are preferably used in combination with thermoplastic fibers. In the heat treatment, the latter migrate to some extent into the matrix of the fiber material present and so constitute the cooling bond sites and renewed stiffening elements. Additionally the addition of thermoplastic fibers means an extension of the present pore dimensions after the heat treatment. In this way it is possible to continuously increase by continuous addition of thermoplastic fibers during the formation of the absorption layer the fraction of thermoplastic fibers to the cover sheet, whereby a similarly continuous increase in the pore sizes. Thermoplastic fibers can be formed from a variety of thermoplastic polymers which have a melting point of less than 190 ° C, preferably between 75 ° C and 175 ° C. At these temperatures, no damage to the cellulose fibers to be likely.

Lengths and diameters of synthetic fibers described above are not particularly restricted, and generally any fiber having a length of 1 to 200 mm and a diameter of 0.1 to 100 denier (grams per 9000 meters) may be preferred given to use. Preferred thermoplastic fibers have a length of 3 to 50 mm, especially preferred a length of 6 to 12 mm. The preferred diameter for the thermoplastic fiber is between 1.4 to 10 decitex, more preferably from 1.7 to 3.3 decitex (gram per 10 000 meters) is. The shape is not particularly limited, and examples include woven types, narrow cylindrical types, cut / chopped yarn, staple fiber types and continuous filament fiber types.

The fibers in the absorbent composition of the present invention can be hydrophilic, hydrophobic or a combination of both. According to the definition of Robert F. Gould in the publication "Contact angle, wettability and adhesion", American Chemical Society (1964), a fiber is referred to as hydrophilic, when the contact angle between the liquid and the fiber (or the fiber surface) is less than 90² is, or when the liquid tends to spread spontaneously on the same surface. The two processes are generally coexistent. Conversely, a fiber is referred to as hydrophobic when a contact angle is formed from greater than 90 ° and no spreading is observed. Preferred hydrophilic fiber material is used. Especially preferred fiber material gets used, which is most hydrophilic weakly hydrophilic on the body side and in the region around the highly swellable hydrogels. In the manufacturing process a gradient is generated through the use of layers of different hydrophilicity, which channels impinging fluid to the hydrogel, where it is ultimately absorbed.

Suitable hydrophilic fibers for use in the inventive absorbent composition are, for example,

Cellulose fibers, modified cellulose fibers, rayon, polyester fibers such. As polyethylene terephthalate (DACRON®), and hydrophilic nylon (HYDROFIL^®). Suitable hydrophilic fibers can also be obtained by hydrophilizing hydrophobic fibers, such as the treatment of thermoplastic fibers obtained olefins from poly (such. As polyethylene or polypropylene, polyamides, polystyrenes, polyurethanes, etc.) with surfactants or silica. However, cellulosic fibers are preferred for reasons of cost and ease of availability.

The highly swellable hydrogel particles are embedded into the fiber material described. This can be done in many ways, by z. B. with the hydrogel material and the fibers together to create an absorbent layer in the form of a matrix, or by incorporating highly swellable hydrogels into fiber mixture layers, where they are ultimately fixed, whether by means of adhesive or lamination of the layers.

The fluid and -distributing fiber matrix may in synthetic fiber or cellulosic fiber or a

Mixture composed of synthetic fiber and cellulosic fiber, wherein the mixing ratio of (100 to 0) synthetic fiber: (0 to 100) can vary cellulose fiber. The cellulosic fibers used may additionally have been chemically stiffened to increase the dimensional stability of the hygiene.

The chemical stiffening of cellulosic fibers can be provided in different ways. Firstly, a fiber stiffening is by adding suitable coatings / Coatings to the fiber material. Such additives include for example polyamide-Epichlorhydrm coatings (Kymene 557H, Hercoles, Inc. Wilmington, Delaware, USA), polyacrylamide coatings (described in US Patent No. 3,556,932 or as a product of Parez® 631 NC, American Cyanamid Co., Stamford, CT, USA), melamine-formaldehyde coatings and polyethyleneimine coatings. The chemical stiffening of cellulosic fibers may be made by chemical reaction. Thus, for. Example, the addition of suitable crosslinker effect crosslinking taking place within the fiber. Suitable crosslinker substances are typical substances used for crosslinking monomers. With included, but not limited thereto, are C₂-C_8th Dialdehydes, C₂-Cs -monoaldehydes Having acid functionality and in particular C₂-C₉ Polycarboxylic. Specific substances from this series are for example glutaraldehyde, glyoxal, glyoxylic acid, formaldehyde and citric acid. These substances react with at least 2 hydroxyl groups within any one cellulose chain or between two adjacent cellulose chains within any one cellulose fiber. The crosslinking causes a stiffening of the fibers that are imbued by this treatment a greater dimensional stability. In addition to their hydrophilic character, these fibers exhibit uniform combinations of stiffening and elasticity. This physical property makes it possible, even under simultaneous contact with fluid and compressive forces pressionskräften the capillary structure and to prevent premature collapse.

Chemically crosslinked cellulose fibers are known and in

WO 91/11162, US Patent 3,224,926, US Patent 3,440,135, US Patent 3,932,209, US Patent 4,035,147, US Patent 4,822,453, US Patent 4,888,093, US Patent 4,898,642 and US Patent 5,137,537 described. The chemical crosslinking imparts stiffening to the fiber material, which is ultimately reflected in improved dimensional stability for the entire hygiene article. The individual layers are so joined together by methods known to those skilled in such. As by heat treatment, addition of hot-melt adhesives, latex binders.

Manufacturing method of the absorbent composition

The absorbent composition is composed of constructions which contain highly swellable hydrogels and the highly swellable hydrogels present in said constructions are or fixed thereto.

Examples of methods by which to obtain an absorbent composition comprising for example, a carrier material, are fixed on one or both sides highly swellable hydrogels are known and included by the invention, but not limited thereto. Examples of methods by which to obtain an absorbent composition comprising for example a fiber material blend of synthetic fibers (a) and cellulose fibers (b) embedded in highly swellable hydrogels (c), wherein the mixing ratio of (100 to 0) synthetic fiber : (0 to 100) cellulose fiber can vary, include (1) a method in which (a), (b) and (c) are mixed simultaneously, (2) a method in which a mixture of (a) and ( b) is blended in (c), (3) a method in which a mixture of (b) and (c) is mixed with (a), (4) a method in which a mixture of (a) and ( c) is mixed into (b), (5) a process are mixed at the (b) and (c) and (a) is continuously metered, (6) are mixed, a method in which (a) and (c) and (b) is metered in continuously, and (7) a method which may be blended separately in (a) in which (b) and (c), a. Of these examples, the methods (1) and (5) are preferred. The apparatus used in this process is not particularly limited and any customary to the person skilled known device can be used.

The absorbent composition obtained can optionally be subjected to a heat treatment, so that an absorption layer having excellent dimensional stability in the moist state. The method for the heat treatment is not particularly limited. Examples include heat treatment by feeding hot air or infrared irradiation. The temperature in the heat treatment is in the range 60 ° C to 230 ° C, preferably between 100 ° C and 200 ° C, more preferably between 100 ° C and 180 ° C.

The duration of the heat treatment depends on the type of synthetic fiber, the quantity and the rate of production of the hygiene article. In general, the duration of the heat treatment range from 0.5 second to 3 minutes, preferably 1 second to 1 mi- nute.

The absorbent composition is generally provided for example with a liquid-pervious topsheet and a liquid impermeable backsheet. Re terhin are leg cuffs and adhesive mounted and so completed the hygiene article. The materials and types of pervious topsheet and impervious backsheet and of the leg cuffs and adhesive tabs are known to one skilled in the art and not particularly limited. Examples can be found in WO 95/26 209th The advantage of the present invention resides in that as cross-linking agents usable ester F after its manufacture does not have to be purified, especially that it is not the carboxylic acid B, for example, acrylic acid, must be removed, since this is a monomer for the preparation of the hydrogels in the rule.

experimental part

In this font used ppm and percentage data relate, unless indicated otherwise, percentages by weight and - ppm.

The inventive method is illustrated by the following example.

Examples

Preparation of acrylate Raw star as Superabsorbervernetzer

The preparation of Superabsorbervernetzer done in the examples by esterifying polyetherols with acrylic acid wherein the removal of the water takes place in azeotroped. Esterification catalyst is sulfuric acid in the examples. The reactants are charged together with a stabilizer mixture consisting of hydroquinone, triphenyl phosphite and hypophosphorous acid in the examples in methyl cyclohexane as entraining agent. The reaction mixture is then heated to about 98 ° C to the azeotropic distillation begins. During the azeotropic distillation, the temperature increases in the reaction mixture. The amount of water removed is determined. Distillation is discontinued when at least the theoretical amount of water was separated. Subsequently, the entraining agent is removed in a vacuum distillation. The product is cooled and used as crosslinkers in superabsorbent production.

Conversion and yield of the reaction is not exactly determined, since the separated in the esterification water also contains acrylic acid and also during the vacuum distillation of the entrainer acrylic acid is removed. Similarly, the crude ester still contains free acrylic acid which is titrated together with the catalyst (acid number).

All amounts are, unless otherwise indicated, parts by weight. Preparation of the ester

Acid numbers were. DIN EN 3682 determined.

Example 1 (Polyethylene glycol 400 diacrylate)

740 parts of polyethylene glycol having an average molecular weight of about 400 (Pluriol® 400®, BASF AG) were esterified with 320 parts of acrylic acid and 5 parts of sulfuric acid in 354 parts of methylcyclohexane. Auxiliaries 3 parts of hydroquinone monomethyl ether, 1 part of triphenyl phosphite and 1 part of hypophosphorous acid was added. There 65 parts of water were removed before the entrainer was removed by vacuum distillation. The product was purified through K300 filter. The acid number was 50.4 mg KOH / g and was adjusted by the addition of 72 parts of acrylic acid in acid number 99 mg KOH / g. The viscosity of the slightly yellowish product (iodine color 1) was 91 mPas.

Example 2 (polyethylene glycol 600 diacrylate)

810 parts of polyethylene glycol having an average molecular weight of about 600 (Pluriol® 600, BASF AG) were esterified with 234 parts of acrylic acid and 5 parts of sulfuric acid in 448 parts of methylcyclohexane. Auxiliaries 3 parts of hydroquinone monomethyl ether, 1 part of triphenyl phosphite and 1 part of hypophosphorous acid was added. There 40 parts of water were removed before the entrainer was removed by vacuum distillation. The product was purified through K300 filter. The acid number was 54 mg KOH / g and was adjusted by adding 70 parts of acrylic acid in acid value 100 mg KOH / g. The viscosity of the slightly yellowish product was 100 mPas.

Example 3 (about 3-fold that is easy depending hydroxy ethoxylated TMP triacrylate)

579 parts 3-tuply ethoxylated trimethylolpropane are esterified with 562 parts of acrylic acid and 5 parts of sulfuric acid in 380 parts of methylcyclohexane. Auxiliaries 3 parts of hydroquinone monomethyl ether, 1 part Triphenylphosphi and 1 part of hypophosphorous acid. Were removed before the entrainer is removed by vacuum distillation 125 parts of water. The product is purified through K300 filter. The Acid number is 38 mg KOH / g. The viscosity of the almost colorless product (iodine color 0-1) is 200 mPas.

Example 4 (approximately 7x per molecule TMP ethoxylated TMP Triacry- lat)

681 parts 7x ethoxylated trimethylolpropane (Polyol TP 70®, Perstorp) were esterified with 414 parts of acrylic acid and 5 parts of sulfuric acid in 365 parts of methylcyclohexane. Auxiliaries 3 parts of hydroquinone monomethyl ether, 1 part of triphenyl phosphite and 1 part of hypophosphorous acid was added. There 102 parts of water were removed before the entrainer was removed by vacuum distillation. The product was purified through K300 filter. The acid number was 26 mg KOH / g and was due to make would be of 105 parts of acrylic acid in acid number 99 mg KOH / g set. The viscosity of the almost colorless product (iodine color 0-1) was 73.2 mPas.

Example 5 (about 15 times per molecule TMP ethoxylated TMP Triacry- lat)

750 parts 15x ethoxylated trimethylolpropane (Emulan® TE15, BASF AG) were esterified with 216 parts of acrylic acid and 5 parts of sulfuric acid in 322 parts of methylcyclohexane. Auxiliaries 3 parts of hydroquinone monomethyl ether, 1 part of triphenyl phosphite and 1 part of hypophosphorous acid was added. There 44 parts of water were removed before the entrainer was removed by vacuum distillation. The product was purified through K300 filter. The acid number was 36 mg KOH / g. The viscosity of the almost colorless product (iodine color 0-1) was 324 mPas.

Example 6 (about 20 times per molecule TMP ethoxylated TMP triacrylate)

830 parts of an approximately 20-fold ethoxylated trimethylolpropane were esterified with 216 parts of acrylic acid and 5 parts of sulfuric acid in 345 parts of methylcyclohexane. Auxiliaries 3 parts of hydroquinone monomethyl ether, 1 part of triphenyl phosphite and 1 part of hypophosphorous acid was added. There were 44 parts of water separated off before the entrainer was removed by vacuum distillation. The product was purified through K300 filter. The acid number was 36 mg KOH / g and was adjusted by the addition of 96 parts of acrylic acid in acid value 101 mg KOH / g. The viscosity of the almost colorless product {iodine color 0-1) was 324 mPas. Example 7 (approximately 3 times per glycerol molecule ethoxylated glycerol triacrylate)

561 parts of an approximately 3-fold ethoxylated glycerol is esterified with 605 parts of acrylic acid and 5 parts of sulfuric acid in 390 parts of methylcyclohexane. Auxiliaries 3 parts of hydroquinone monomethyl ether, 1.5 parts of triphenylphosphite and 1.5 parts of hypophosphorous acid. Were removed before the entrainer is removed by vacuum distillation 130 parts of water. The product is purified through K300 filter. The acid number is 30 mg KOH / g. The viscosity of the almost colorless product (iodine color 0-1) is 380 mPas.

Example 8 (about 5 times per glycerol molecule ethoxylated glycerol triacrylate)

940 parts of an approximately 5-fold ethoxylated glycerol (Lupranol® VP9209, BASF Schwarzheide GmbH) was esterified with 670 parts of acrylic acid and 6 parts of sulfuric acid in 500 parts of methylcyclohexane. Auxiliaries 3 parts of hydroquinone monomethyl ether, 1.5 parts of triphenyl phosphite and 1.5 parts of hypophosphorous acid was added. Were removed before the entrainer is removed by vacuum distillation 44 parts of water. The product is purified through K300 filter. The acid number is 29 mg KOH / g.

Example 9 (approximately 9 times per glycerol molecule ethoxylated glycerol triacrylate)

704 parts of an approximately 9-fold ethoxylated glycerol (Lutron® HF1, BASF AG) was esterified with 363 parts of acrylic acid and 5 parts of sulfuric acid in 356 parts of methylcyclohexane. Auxiliaries 3 parts of hydroquinone monomethyl ether, 1.5 parts of triphenyl phosphite and 1.5 parts of hypophosphorous acid was added. There 76 parts of water were removed before the entrainer was removed by vacuum distillation. The product was purified through K300 filter. The acid number was 71 mg KOH / g and was adjusted by the addition of 8 parts of acrylic acid to an acid number of 100 mg KOH / g. The viscosity of the almost colorless product (iodine color 0-1) was 113 mPas.

Example 10 (about 5 times per molecule Pentaerythri ol ethoxylated pentaerythritol tetraacrylate)

382 parts of an approximately 5-fold ethoxylated Pentaerytrithols are esterified with 348 parts of acrylic acid and 5 parts of sulfuric acid in 180 parts of methylcyclohexane. Auxiliaries are 3 parts of hydroquinone monomethyl ether, 1.5 parts of triphenyl phosphite and 1.5 Part of hypophosphorous acid is added. Were removed before the entrainer is removed by vacuum distillation 72 parts of water. The product is purified through K300 filter. The acid number is 35 mg KOH / g. The viscosity of the dark-colored GE product (iodine color not determinable) is 280 mPas.

Example 11 (about 13 times per molecule ethoxylated Dipentaerytri- menthol)

545 parts of an approximately 13-fold ethoxylated Dipentaerytrithols (DPP 130 from Perstorp AB) are esterified with 585 parts of acrylic acid and 5 parts of sulfuric acid in 400 parts of methylcyclohexane. Auxiliaries 3 parts of hydroquinone monomethyl ether, 1.5 parts of triphenyl phosphite and 1.5 part of hypophosphorous acid. Were removed before the entrainer is removed by vacuum distillation 130 parts of water. The product is purified through K300 filter. The acid number is 45 mg KOH / g. The viscosity of the light-colored product (iodine color 1-2) is 1600 mPas.

Example 12 (about 4 times per molecule Ethoxylated Sorbitol Acrylate)

490 pieces approximately 4-fold ethoxylated sorbitol are esterified with 444 parts of acrylic acid and 5 parts of sulfuric acid in 448 parts of toluene. Auxiliaries 3 parts of hydroquinone monomethyl ether, 1.5 parts of triphenyl phosphite and 1.5 part of hypophosphorous acid. Were removed before the entrainer is removed by vacuum distillation 96 parts of water. The product is purified through K300 filter. The acid number is 45 mg KOH / g. The viscosity of the dark-colored product (iodine color number 3-4) is 990 mPas.

Example 13 (about 6 times per molecule Ethoxylated Sorbitol Acrylate)

601 parts of an approximately 6-fold ethoxylated sorbitol are esterified with 444 parts of acrylic acid and 5 parts of sulfuric acid in 448 parts of cyclohexane. Auxiliaries 3 parts of hydroquinone monomethyl ether, 1.5 parts of triphenyl phosphite and 1.5 part of hypophosphorous acid. Were removed before the entrainer is removed by vacuum distillation 96 parts of water. The product is purified through K300 filter. The acid number is 45 mg KOH / g. The viscosity of the dark-colored product (iodine color number 2-3) is 700 mPas. Example 14 (about 8 times per molecule Ethoxylated Sorbitol Acrylate)

689 parts of an approximately 8-fold ethoxylated sorbitol are esterified with 444 parts of acrylic acid and 5 parts of sulfuric acid 5 in 448 parts of toluene. Auxiliaries 3 parts of hydroquinone monomethyl ether, 1.5 parts of triphenyl phosphite and 1.5 part of hypophosphorous acid. Were removed before the entrainer is removed by vacuum distillation 100 parts of water. The product 10 is purified through K300 filter. The acid number is 45 mg KOH / g. The viscosity of the dark-colored product (iodine color number 5) is 700 mPas.

Example 15 (about 10 times per molecule of ethoxylated sorbitol 15 acrylate)

788 parts of an approximately 8-fold ethoxylated sorbitol are esterified with 444 parts of acrylic acid and 5 parts of sulfuric acid in 448 parts of toluene. Auxiliaries are 3 parts of hydroquinone monomethyl

20 ether, 1.5 parts of triphenyl phosphite and 1.5 parts of hypophosphorous acid is added. Were removed before the entrainer is removed by vacuum distillation 106 parts of water. The product is purified through K300 filter. The acid number is 45 mg KOH / g. The viscosity of the dark-colored product (iodine color

25 10-15) is 500 mPas.

Example 16 (about 13 times per molecule of ethoxylated sorbitol Hexaa- methacrylate)

30 625 parts of an approximately 13-fold ethoxylated sorbitol was esterified with 518 parts of acrylic acid and 5 parts of sulfuric acid in 381 parts of methylcyclohexane. Auxiliaries 3 parts of hydroquinone monomethyl ether, 1.5 parts of triphenyl phosphite and 1.5 parts of hypophosphorous acid was added. There 116 parts of water were separated

35 before the entrainer was removed by vacuum distillation. The product is purified through K300 filter. The acid number was 78 mg KOH / g. The viscosity of the dark-colored product (iodine color number not determined) was 406 mPas.

40 Preparation of hydrogels

To determine the quality of the surface cross-linking the dried hydrogel can be investigated by the following test methods.

5 test Methods

a) Centrifuge Retention Capacity (CRC Centrifuge Retention Ca pacity)

This method measures the free swellability of the hydrogel in a teabag. To determine CRC, 0.2000 ± 0.0050 g of dried hydrogel (particle size fraction 106-850 .mu.m) are weighed into a 60 x 85 mm in size tea bags, which is subsequently sealed. The teabag is placed for 30 minutes in an excess of 0.9.% Saline solution (at least 0.83 1 saline solution / lg of polymer powder). The teabag is then centrifuged for 3 minutes at 250 g. The determination of the amount of liquid by weighing the centrifuged teabag.

b) absorption under load (AUL Absorbency Under Load) (0.7 psi)

The measuring cell for determining AUL 0.7 psi is a Plexiglass cylinder having an inner diameter of 60 mm and a height of 50 mm, of a stainless steel sieve bottom glued to its underside with a mesh size of 36 μ. The measuring cell further includes a plastic plate having a diameter of 59 mm and a weight which can be placed together in the plastic plate in the measuring cell. The weight of the plastic plate and the weight totals 1345 g. To perform the determining AUL 0.7 psi is the weight of the empty Plexiglas cylinder and of the plastic plate and recording it as W. 0.900 ± 0.005 g of hydrogel-forming polymer (particle size distribution 150-800 .mu.m) is weighed into the Plexiglas cylinder and distributed very uniformly over the stainless steel sieve bottom. The plastic plate is then carefully placed in the Plexiglas cylinder and weighed the entire unit; the weight is as W_a written down. The weight is then placed on the plastic plate in the Plexiglas cylinder. In the middle of a Petri dish with a diameter of 200 mm and a height of 30 mm, a ceramic filter plate is placed with a diameter of 120 mm and a porosity 0 and sufficient 0.9 wt.% Sodium chloride solution filled that the liquid surface with the filter plate surface closes without the surface of the filter plate being wetted. A round filter paper having a diameter of 90 mm and a pore size is &lt;20 μ (S &amp; S 589 Black from Schleicher &amp; Schull) is placed on the ceramic plate. The containing hydrogel-forming polymer Plexiglas cylinder is then placed with plastic plate and weight on the filter paper and left there for 60 minutes sen. After this period, the complete unit is taken out of the Petri dish from the filter paper and then removed the weight from the Plexiglas cylinder. The swollen hydrogel containing Plexiglas cylinder, together with the plastic plate and the weight recorded as.

Absorbency under load (AUL) is calculated as follows:

AUL 0.7 psi [g / g] = [W_b-W_a] / [W_a-W₀]

The AUL 0,5psi is measured analogously a lower pressure.

c) The determination of the extractable content after 16 h (Extract. 16h) was carried out analogously as described in EP-AI 811 636, page 13, line 1 to line 19 described.

Example 18-27:

Preparation of the base polymer

In a laboratory kneader (Werner and Pfleiderer LUK 8.0 K2) 6 kg of 40 percent were.% Aqueous acrylic acid solution presented, which was neutralized to 77 mol% with sodium hydroxide.

Crosslinkers the types shown in Table 1 were in each case in the amounts specified therein added on acrylic acid used. After% sodium persulfate and 0.0056% ascorbic acid were as polymerization 0.28 wt. Wt. Added -jeweils based on starting Acrylsäuremonomer-.

The reaction started, and the temperature of Knetermantels was readjusted so that the heat of reaction was not discharged via the casing. This leads to an almost adiabatic heat-up of the reaction mixture wobie the polymerization occurs under stirring. At the end point the reaction the temperature is still maintained about one hour. Thereafter, each a fine crumb-gel could be emptied.

The gel was dried for 3 hours at 160 C in a circulating air cabinet, ground using a laboratory roll mill, and at 100 - to 850 micrometers. This is the normal base polymer of Table 1 below.

Alternatively, the gel was first 6h annealed at 90 C in a sealed plastic bag, and only then was dried for 3 hours at 160 C in a circulating air cabinet, ground using a laboratory roll mill, and finally at 100-850 microns sieved. This is the hydrolyzed base polymer Table 1.

postcrosslinking:

The dry normal base polymer powder was mixed with a solution of 0.06 wt.% Ethylene glycol (Nagase, Japan), 3.43 wt.% Water and 1.47 wt.% Propane-1, 2 -jeweils based on starting with polymer stirring sprayed homogeneously. The wet powder was then heat treated in a drying oven at 150 C for 60 min. Thereafter, again sieved at 850 microns to remove agglomerates. The properties of this postcrosslinked polymer were determined and are listed in Table 1 below.

Table 1

σ- to

<img id="imgf000063_0001" he="69" wi="211" file="imgf000063_0001.tif" img-format="tif" img-content="table" orientation="landscape" inline="no" />

The solubility of the crosslinker is determined by adding the crosslinking agent to the reaction mixture at room temperature. The assessment is made visually. The following scale is used Clear = complete clear solution

Down = naked eye observable significant turbidity in the solution drops = floating of the crosslinking agent in drop form The other products of the invention can be reacted analogously.