Flame-resistant modacrylic fibers and filaments and process for their manufactura

Flameproof modacrylic fibers and threads with improved thermal properties and processes for their production

The invention relates to flame-retardant threads and fibers made from copolymers of acrylonitrile with vinyl chloride, vinyl bromide and / or vinylidene chloride, which with carboxyphosphinic acid derivatives of the general formula r₂0'

X

II 'P c

C = CH, I

R-, (I), in which and R₂ are lower alkyl or haloalkyl radicals having not more than eight carbon atoms, R ^ is a hydrogen atom or a methyl group, X is an oxygen or sulfur atom and Y is a branched or unbranched alkylene group having 1 to 6 carbon atoms.

It is generally known to render polymers flame-retardant by adding or incorporating phosphorus-containing compounds. Vinyl or allylphosphonic acid derivatives have hitherto been used as phosphorus-containing modification compounds. Carboxylic acid derivatives of phosphine oxide have already been described in DT-OS 2 052 568. Movie theater !

The use of carboxyphosphonic acid and carboxyphosphinic acid derivatives for the production of flame-retardant polystyrene can be found in SU-PS 168 M58.

It has been found that in copolymers of acrylonitrile with vinyl bromide, vinylidene chloride and / or vinyl chloride, considerably improved flame retardancy can be obtained by adding compounds of phosphine oxide, while the corresponding phosphonic acid derivatives give practically no flame retardancy improved by synergism. A disadvantage of the polymers modified with phosphine oxide compounds in accordance with DT-OS 2 052 568 and in particular the filaments and fibers produced therefrom is the poor thermal stability of these polymers or the structures formed therefrom.

Surprisingly, it has now been found that copolymers of acrylonitrile modified with carboxyphosphinic acid derivatives with vinyl chloride, vinyl bromide and / or vinylidene chloride, polymers or Threads and fibers made from these polymers result in a significantly higher thermal stability with comparable flame retardancy.The threads and fibers made from these polymers therefore have a significantly lower tendency to yellowing at elevated temperatures than the previously known flame-retardant modified modacrylic threads and fibers , Modacrylic fibers are to be understood as meaning the multipolymer fiber materials which are composed of at least 55% by weight and at most 85% by weight of acrylonitrile units.

The filaments and fibers according to the invention are obtained by spinning products which are formed by copolymerization of acrylonitrile and optionally other unsaturated compounds with an activated double bond together with vinyl chloride, vinyl bromide and / or vinylidene chloride and carboxyphosphinic acid derivatives corresponding to formula I. The copolymers on which the filaments and fibers are based preferably contain 5 to 5% by weight of vinyl chloride, vinyl bromide and / or vinylidene chloride building blocks and 5 to 50% by weight of building blocks which are derived from compounds of the formula I. The weight percentages given here. each relate to the overall polymer.

- 3 Optimal properties are observed in threads and fibers, the fiber substances of which are obtained by polymerizing acrylonitrile and possibly other unsaturated compounds with activated double bond and from W to 30% by weight of vinyl chloride, vinyl bromide and / or vinylidene chloride and 8 to 20% by weight of carboxyphosphinic acid derivatives of formula I were obtained.

The compounds of the general formula X are expediently prepared by the process described in the co-pending patent application P (HOE 7VF 302), using, for example, alcohols of the general formula II

R, X ¹ IS ____

<img file="LU73604A1_D0001.tif" />

in which R ^, R₂, X and Y have the meanings given above, for example with stoichiometric amounts of an acid halide of the general formula III

Z - CO - C = CH "t

R, (III) in which Z is a halogen atom and R ^ has the meaning given above, in an inert solvent, for example toluene, with addition of equimolar amounts of a base such as, for example, triethylamine, and a polymerization inhibitor at temperatures between 20 and 50 ° C. implements. After the hydrochloride formed has been filtered off, the solvent is drawn off and the product is distilled in vacuo.

The copolymers required for the production of the threads and fibers according to the invention can have been prepared, for example, using the following phosphorus-containing carboxylic acid derivatives derived from formula I: the acrylic acid and methacrylic acid esters of mefchyl-hydroxymethylphosphinsuremethyl-, ethyl-, -propyl-, - isobutyl ester, ethyl hydroxymethylphosphinic acid methyl, ethyl,

propyl_t -isobutyl-ester, methyl-2-hydroxyethylphosphinic acid isobutyl ester, propyl-2-hydroxyethylthiophosphinic acid isobutyl ester, propyl-2-hydroxyethylphosphinic acid propyl ester, methyl (2-hydroxy2-methyl-ethyl) -phosphinic acid methyl, ethyl, propyl, methyl ~, -isobutyl-, -pentyl-ester, isobutyl methyl-3-hydroxypropylphosphinate, isopropyl butyl-3-hydroxypropylphosphinate.

The polymerization of the phosphorus-containing carboxylic acid derivatives of the formula I with acrylonitrile and other unsaturated compounds with an activated double bond takes place according to the processes known for the copolymerization of acrylonitrile, that is to say by ionic, radical or redox catalysis processes, in solution or dispersion as a solution or pearl - or precipitation polymerization or in bulk. In general, free-radical or redox polymerization is preferable to ionic polymerization, which gives lower degrees of polymerization and yields, particularly in the case of acrylic acid esters.

As. Catalyst systems are possible, for example:

Hydrogen peroxide, potassium or ammonium peroxodisulfate, dibenzoyl peroxide, tert-butyl hydroperoxide, .di-tert, -butyl peroxide and other organic peroxides, diazomethane, azoisobutyronitrile and derivatives, diazonium and diazo compounds, inorganic and organic peroxides in combination with iron ~ salt, with sodium bisulfite, sulfinic acids or? 4ercaptans. The reaction can also be excited by radical-forming radiation.

Numerous organic compounds are suitable as solvents or diluents, for example dimethylformamide, chlorobenzene, methanol, xthanol, i-propanol, acetone. It is particularly advantageous to work in aqueous systems. Common emulsifiers and protective colloids can be added to the polymerization in the heterogeneous phase,

The following compounds may be mentioned as further comonomers with activated double bond:

Acrylamide, acrylic acid and its esters, vinyl esters and ethers such as vinyl acetate, vinyl stearate, vinyl butyl &amp; 'ther, vinyl ilalogenoacetate, such as vinyl bromoacetate, vinyl dichloroacetate, vinyl trichloroacetic acid, styj / ol, maleimide, etc.

- 5 studies have shown that filaments and fibers made of polymers which were obtained only by polymerizing carboxylic acid derivatives of the general formula I and acrylonitrile have only a low level of flame retardancy. Flame retardancy only becomes optimal if, in addition to acrylonitrile, halogen-containing comonomers vinyl chloride, vinyl bromide and / or vinylidene chloride are also incorporated into the polymer. Self-extinguishing fibers can only be obtained under these conditions.

The polymers obtained are soluble in the solvents known for polyacrylonitrile, such as, for example, dimethylformamide, dimethylacetamide, dimethyl sulfoxide or ethylene carbonate. The solutions which can be prepared with these solvents can be spun by the processes known for spinning polyacrylonitrile by, for example, pressing the polymer solutions through nozzles into a precipitation bath consisting of the solvent and a non-solvent, and stretching and forming the threads thus formed in further BSder frees the solvents used and then dries the threads obtained. Because of the good thermal stability of the polymers described, however, it is also possible to obtain threads and fibers by known dry spinning processes, it being possible for staple fibers to be produced by cutting the spun tow obtained by known processes.

The following examples are intended to illustrate the present invention.

- 6 Example 1

In one

1 Steel boilers were metered in continuously:

250 ml / h of a Konomerewachs.es consisting of 71 parts by weight of acrylonitrile, 15 parts by weight of vinylidene chloride and 14 parts by weight of a compound of formula

CH,

3H, C ³ V pCH-CH₂O'

H, C ') 0 &lt;it&gt; -CH₂-CH₂-O ~ C-CH = CH₂

250 ml / h of a solution of 10 g sodium acetate, 15 S sodium methallylsulfonate and. Mohr's salt in 1750 ml of water, which was adjusted to a pH of 2.5 with sulfuric acid,

Variable amounts of a solution of potassium peroxodisulfate in water and a solution of sodium disulfite in water.

The weight ratio of potassium peroxodisulfate to sodium disulfite was 1: 4. The required amounts were determined by the degree of polymerization aimed for.

The polymerization was carried out at 55 ° C. under pressure. The polymer suspension which formed was continuously discharged after a residence time of 1 hour, a conversion of about 80 being able to be obtained. The polymer was washed carefully and dried.

The relative viscosities were measured at 25 ° C in a 0.5% solution in dimethylformamide,

The polymer was introduced into dimethylformamide at 0 to -20.degree. C. while stirring and then stirred at 60.degree. C. for 1/2 hour. The solution was then filtered and degassed. The polymer content of the t

Spinning solutions was $ 15-30% by weight based on the total

Solution. The spinning solution was pressed through a 100-hole nozzle, hole diameter 80 pm, into a filling bath which consisted of 65% dimethylformamide and 35% aur: water. The temperature of the spinning

- Ί bath was 30 ° C. The threads obtained in this way were stretched about four times in two other hot baths with a lower dimethylformamide content, washed in further baths with water and dried on hot godets. After drying, it was stretched again by 25% of its length. The threads thus obtained were steamed at 110 ° C. and processed into a knitted tube on a Velha circular knitting machine.

The textile values ​​given in Table 2 were determined after steaming. The knitted tube obtained was washed a few times, dried and tested on a bow tester according to DIN 54331.

The thermal stability was tested both on the polymer powder and on the threads spun from it.

The polymer powder was sieved and subjected to thermal stress in a drying cabinet at 150 ° C. for two hours. The fibers were also exposed to a temperature of 150 ° C in a drying cabinet for two hours. The measurements were carried out using an Elrepho remission photometer from Zeiss. The Helligkoit was determined with a color measuring filter FMY / C, which was compared to a calibrated MgO working standard.

The results obtained are shown in Tables 1 and 2

Examples 2 and 3, in agreement with Example 1, were used to produce further copolymers and to thread them. The different test conditions and the results obtained are shown in Tables 1 and 2 below.

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Φ

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C φ

ε

<td></td><td>x</td><td>O</td><td></td><td></td><td></td><td></td>

<td>VS.</td><td>CM</td><td>m</td><td></td><td></td><td></td><td></td>

<td>KX</td><td></td><td> *-5</td><td></td><td></td><td></td><td></td>

<td></td><td>X</td><td></td><td></td><td>b-</td><td>O</td><td>σ \</td>

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<td></td><td></td><td></td><td></td><td></td><td></td><td></td>

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<td>• ri</td><td>Û)</td><td></td><td></td><td></td><td></td><td></td>

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<td>rh</td><td> 0,</td><td></td><td></td><td>Λ</td><td> »&gt;</td><td></td>

<td>Φ</td><td>O</td><td></td><td></td><td>KO</td><td>I / O</td><td>LXO</td>

<td>X</td><td> &gt;</td><td></td><td></td><td>co</td><td>co</td><td>CO</td>

<td> 0)</td><td></td><td></td><td></td><td></td><td></td><td></td>

<td>"P</td><td></td><td></td><td></td><td></td><td></td><td></td>

<td>P</td><td></td><td></td><td></td><td></td><td></td><td></td>

<td>Φ</td><td></td><td></td><td></td><td></td><td>O</td><td>- = r</td>

<td> ?</td><td></td><td></td><td>I / O</td><td>σο</td><td> *0</td><td> ·*</td>

<td>c</td><td>rh</td><td></td><td> *\</td><td></td><td>K \</td><td>K \</td>

<td>φ</td><td>O</td><td></td><td>KO</td><td>ru</td><td>rh</td><td>ri</td>

<td>ω</td><td></td><td></td><td>tH</td><td>Ti</td><td></td><td></td>

<td> &gt;5</td><td>vi</td><td></td><td></td><td></td><td></td><td></td>

<td>ri</td><td></td><td></td><td></td><td></td><td>t</td><td>CO</td>

<td>Cue</td><td> 0-,</td><td></td><td>M3</td><td>σ \</td><td> »0</td><td></td>

<td>c</td><td></td><td></td><td>A</td><td> **</td><td>xH</td><td>Ή</td>

<td> &lt;</td><td>IA</td><td></td><td>rh</td><td>xH</td><td></td><td></td>

<td> •</td><td></td><td></td><td></td><td></td><td>CM</td><td>CA</td>

<td>rh</td><td></td><td></td><td></td><td></td><td>n</td><td></td>

<td>Φ</td><td></td><td></td><td> =-</td><td>O</td><td>eu</td><td>\H</td>

<td>p</td><td></td><td></td><td> •0</td><td> •0</td><td>z S</td><td>zs.</td>

<td></td><td></td><td></td><td>tu</td><td>eu</td><td>cti</td><td>X</td>

<td>SF</td><td></td><td></td><td></td><td></td><td></td><td></td>

<td colspan="3"></td><td></td><td></td><td colspan="2"></td>

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Acrylnifcnl

vinylidene

Phosphorus derivative r

i

HHU cm r'I ο ο n &lt;&gt; p. &lt;

<img file="LU73604A1_D0002.tif" />

The results of the tables show that in the case of modacrylic threads and fibers and the copolymers on which they are based, the thermal stability is strongly dependent on the type of phosphorus derivative used. With approximately the same phosphorus content in the copolymer, the flame retardancy is practically the same when using phosphinic acid derivatives and phosphine oxide derivatives, but after exposure to temperature the copolymer modified with phosphine oxide derivatives shows a strong discoloration, which is clearly expressed in the brightness values ​​given.

n

HOE 74 / f 300