Condensation polymers

SWEDEN

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PUBLISHING WRITING No. 367 641 int ci C 08 g 17/02

PATENTS AND REGISTRATION OFFICE

Patent Application. No. 7749/71 Validity Day on Ans. widely available on

Ans. published and the publication published the Priority requested from (GB, 29 125)

Received 15 VI 1971 15 VI 1971 17 XII 1971

VI 1974, 16 VI 1970

IMPERIAL CHEMICAL INDUSTRIES LTD, LONDON, GB

Inventor: DJ Walbridge, Beaconsfield and AS Baker, Slough

Agent: PU Brain

Hydroxyl group-containing polyester for use in one composite coating composite

The present invention relates to condensation polymers and in particular relates to condensation polymers which are useful in coating compositions.

The nature of condensation polymers, prepared from monomeric compounds, depends primarily on the functionality and relative proportions of the compounds involved in the condensation reaction carried out to form the polymers, and on the chemical nature and reactivity of the functional chemical groups. who are present in the associations. In the manufacture of alkyd resins, phthalic acid and glycerol are co-condensed, optionally together with compounds of lower or higher functionality, such as benzoic acid or pentaerythritol, useful polymers of high molecular weight are obtained only when the relative proportions of compounds of different functionality are carefully weighed. If the proportion of trifunctional or right-functional compounds is too large, very high cross-linked resins are obtained as a result of the condensation reaction, and these resins are unsuitable in coating compositions. Accordingly, since it has hitherto been a desire to produce an alkyd resin containing a relatively large amount of hydroxyl groups, it has been customary to use an excess of tri- or right-functional polyol Dupl.kl. C 08 g 39/02 and to limit the extent of the condensation so that the resin has a relatively low molecular weight.

When a monomer A - BB (where the group A can be condensed with the group B) is condensed, a condensation polymer is formed in which each polymer molecule contains only one group A and a number of groups B, the actual number of B groups increasing with the number of monomer molecules. which takes part in the condensation. Detailed information on this can be found, among other things. in Flory, Principles of Polymer Chemistry, p. 361 (Cornell UP 1965). In this reaction, the condensation polymer formed is highly branched but not yet intermolecular bridged (so that a gel formation is excluded) and the polymer is highly functional with respect to group B, whereas only monofunctional with respect to group A. Monomer A - BB can also co-condensed with monomer A - B to form a polymer molecule which is still monofunctional with respect to A, but which has fewer numbers of B groups.

It has now been found that condensation polymers, obtained by co-condensation of certain monomer compounds containing certain monomers A - BB, are useful in coating compositions. The condensation of these selected monomers can be extended to relatively high molecular weights and the excess of the remaining group B in the polymer provides an agent whereby the molecular weight of the polymer can be further increased, e.g. after application of a composition on a substrate and optionally with bridging.

In accordance with the present invention, hydroxyl group-containing polyesters are obtained by condensation in a manner known per se at a temperature lower than 200 ° C of a polyhydroxymonocarboxylic acid of the formula R (HOCH₂)₂ - C - COOH, where R represents an alkyl group containing 1-3 carbon atoms, or represents a - CH₂OH group, in the absence of any compound, containing more than one carboxyl group or a group equivalent to more than one carboxyl group. One group, equivalent to more than one carboxyl group, is e.g. a carboxylic anhydride group.

Acids of the structure shown in the above formula have been previously proposed for use in the preparation of certain condensation polymers, especially those polymers to be used in coating compositions dispersed in an aqueous medium where free carboxyl groups are required in the final polymer. However, in previously proposed and practiced condensation reactions, these polyhydroxime monocarboxylic acids have been co-condensed with polycarboxylic acids, t

phobalic acid, and the carboxyl group, bound to a tertiary carbon atom, have been found to be difficult to esterify, so that it remains substantially unesterified, in the finished polymer. It has now, quite surprisingly, been found that in the absence of a polycarboxylic acid, the carboxyl group is easily esterified, both in self-condensation and co-condensation with e.g. monohydroximonocarboxylic acids or monoaminomonocarboxylic acids. In addition, an ester group located adjacent to a tertiary carbon atom is hydrolyzed less readily and undergoes ester exchange or alcoholysis less readily than is the case for an ester group which is not adjacent to a tertiary carbon atom. The latter advantage is of particular importance when a condensation polymer of the present invention, having a high hydroxyl content, is subsequently to be esterified with a carboxylic acid, since the polymer is resistant, under current esterification conditions, to random degradation to low molecular weight products.

Polyhydroxime monocarboxylic acids which contain a tertiary carbon atom and have the above structure include dimethylol propionic acid, dimethylolbutyric acid, dimethylol valeric acid and trimethylolacetic acid. The preferred acid is dimethylol propionic acid. Because of their low molecular weight and high hydroxyl content, these acids enable the preparation of condensation polymers for use in coating compositions having a high concentration of hydroxyl groups, suitable for subsequent bridging or other modification, e.g. esterification with drying oil fatty acids, as discussed in more detail below.

Condensation polymers may be self-condensed by the polyhydroxime monocarboxylic acids, in which case highly branched polymers of high molecular weight and high hydroxyl content can be produced. The polyhydroximonocarboxylic acids can also be co-condensed with monohydroximonocarboxylic acids and / or monoaminomonocarboxylic acids, if it is desired to modify the self-condensate, e.g. with respect to molecular weight, branching, hydroxyl functionality or solubility in certain solvents. Suitable monohydroxime monocarboxylic acids include 12-hydroxy stearic acid, 12-hydroxy oleic acid and lactic acid. Suitable monoaminomonocarboxylic acids include glycine, 6-aminocaproic acid and 11-aminodecanoic acid.

The solubility and bridging potential of the condensation polymers of the present invention can be varied by varying the amount and type of the monohydroxime monocarboxylic acid used in the co-condensation. The particular composition used is determined by the final application. For example, a self-condensed dimethylol propionic acid has a hydroxyl number of about 480 mg KOH / - and is soluble only in polar solvents such as dimethylformamide. In contrast, a co-condensate of 1 part dimethylpropionic acid and 1 part 12-hydroxystearic acid has a hydroxyl number of about 200 mg KOH / g, is soluble in xylene / butanol, provides a highly bridged film with an aminoplast or is alternatively suitable to esterify with soybean oil. fatty acid to give an air-drying resin which is soluble in mineral turpentine. A co-condensate of 2 parts of dimethylol propionic acid and 8 parts of 12-hydroxy stearic acid has a hydroxyl number of 80 mg KOH / g and is also soluble in mixtures of xylene and butanol.

Monocarboxylic acids, monohydroxy compounds or polyhydroxy compounds may also be present in the condensation reaction, but it is preferred in accordance with the invention that the proportion of such monomer compounds be kept to a minimum. Suitable monocarboxylic acids include lauric, oleic and benzoic acids and suitable monohydroxy compounds include butanol and decanol. Suitable polyhydroxy compounds include pentaerythritol. Since it is a desire to obtain a condensation polymer containing the maximum number of carboxyl groups, it is, of course, necessary to exclude the monohydroxy and polyhydroxy compounds.

Although the presence of a monocarboxylic acid in the condensation reaction may be of value in that it acts on, and thereby also, to some extent, controls the molecular weight and branching of the polymer and maintains the solubility of the reaction solvent, it is however preferable to form a polymer, suitable for use in coating compositions wherein a high molecular weight condensation polymer containing a high proportion of hydroxyl groups, reacted with a monocarboxylic acid. Preferably, the monocarboxylic acid is a drying oily fatty acid to give a highly functional, autoxidizable, bridging polymer as described above.

The condensation polymers can be prepared by conventional methods, e.g. by melt polymerization or polymerization in the presence of a solvent, whereby the eliminated water is removed by szotropic distillation. The reaction conditions must be chosen so that the feeding of hydroxyl groups and the resulting bridging are excluded. This is normally achieved by keeping the reaction temperature below 200 ° C and in accordance with a preferred preparation method, an esterification catalyst, e.g. zirconium naphthenate or dibutyltin oxide, at a reaction temperature of cal 50 -19 ° C.

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The condensation polymers prepared in accordance with the present invention and residues thereof are of particular value as components of coating compositions, since they generally contain a large proportion of hydroxyl groups which are brideable under suitable conditions, e.g. with aminoplast or phenolic bridging resins, and which also constitute a means for introducing bridging or bridging residues, e.g. by esterification with drying oil residues. At the same time, the molecular weight of such a condensation polymer, applied to a substrate prior to bridging, can be relatively high, without the associated risk of gelling during its preparation, as is the case with conventional alkyd resins, and is thus still soluble in the conventional solvents. Although the condensation polymers can be used as such, it is often more convenient to bind such a polymer to another part, e.g. via an ester bond, to an addition polymer body, the remainder of the condensation polymer providing the advantages just mentioned.

Where the condensed monomer compounds include polyhydroxymonocarboxylic acid and optionally monohydroxymonocarboxylic acid and / or monocarboxylic acid, but exempted mono- and polyhydroxy compounds, the resulting condensation polymer is always monofunctional with respect to the carboxyl group. Such a polymer is of value in chemical syntheses because it can be readily and unambiguously reacted by the carboxyl group by condensation with other co-condensable groups or the carboxyl group can be modified to give another reactable group. Thus, residues of the condensation polymers which form the subject of the present invention can be bonded to other chemical units to provide valuable materials, especially for use in coating compositions. Alternatively, the only carboxyl group as such may be retained in the polymer, e.g. when the polymer is to be dispersed in an aqueous medium in the presence of a base.

Examples of reactions in which the carboxyl group is condensed with other groups include reactions with an isocyanate, a monohydroxy or polyhydroxy compound or an epoxide. It may be a desire e.g. to increase the hydroxyl functionality of the polymer and this can be achieved by reacting the polymer subsequently with a polyol such as pentaerythritol. The hydroxyl groups in the resulting polymer can then be esterified with an acid for introduction of bridgeable groups, e.g. by esterification with a drying oil-fatty acid. The high proportion of drying oil residues introduced thereby is advantageous in coating compositions, which are hardened by an autoxidation mechanism. Other auto-oxidizable groups, e.g. allyl ether groups, may also be introduced into the polymers of the present invention by reacting the hydroxyl groups with an intermediate containing such other groups. The hydroxy groups can also be bridged by reaction with aminoplast or phenolic resins, e.g. melamine / formaldehyde resins, or with isocyanates, e.g. adducts of trimethylol propane and toluylene diisoeyanate. The carboxyl-containing polymer can be reacted with the epoxide groups in an epoxy resin, whereby the hydroxyl groups in such a resin may optionally be further esterified with carbonic acid.

The carboxyl group of the polymer can be modified to give in the polymer another reactive group, e.g. a polymerizable, ethylenically unsaturated group, by reaction with glycidyl methacrylate or a similar monomer, an epoxide group by reaction with epichlorohydrin, or a hydroxy ester group by reaction with a simple epoxide. Condensation polymers in which the carboxyl group is replaced by a group containing a polymerizable ethylenically unsaturated group can be copolymerized with one or more polymerizable ethylenically unsaturated monomers to form a finished polymer having a backbone of addition polymer from which residues of condensation polymer depend . The addition polymer backbone may be of high molecular weight and, as a result of the hydroxyl groups contained in the suspended condensation polymer residues, the entire polymer may be subsequently bridged to give a final high molecular weight and complex structure which is highly resistant to degradation and chemical attack. Such bridging can be achieved, e.g. after application to a substrate, by reaction with a bridging agent or alternatively by esterification of the hydroxyl groups with a drying oil-fatty acid, whereby the drying oil residues are bridged upon exposure in air. These polymers are useful in coating compositions and an advantage over the conventional monomer-modified alkyd resins is that they are substantially free of addition polymer, unmodified with condensation polymer, and from unmodified condensation polymer. Accordingly, there is no problem of solvent combinability of the addition polymer and condensation polymer components.

The condensation polymers of the present invention and polymeric portions thereof are also useful in preparing dispersions of two-way copolymer assemblies and coating compositions containing such dispersions are disclosed in South African Patents Nos. 5612/70, 5613/70 and 5615/70. They are also of value in providing stabilization bridging sites which stabilize certain polymer dispersions, as described in South African Patent No. 4596/70.

The polymers of the present invention, and polymeric portions thereof, may also be used e.g. as, or in the manufacture of, pigment dispersants and plasticizers.

The invention is further illustrated by means of the following exemplary embodiments, in which the indicated parts and percentages relate to parts by weight and by weight respectively. weight percent, unless otherwise noted in the text.

Example 1 'This example describes the preparation of a condensation polymer of dimethylolpropionic acid.

A mixture of 200 parts of dimethylol propionic acid, 80 parts of dimethylformamide and 2 parts of zirconium naphthenate was heated under reflux. In the reaction, water formed together with the dimethylformamide distillate was removed. Additional amounts of dimethylformamide were added to maintain reflux and the reaction was continued until the acid number dropped to 15 mg KOH / g resin. The final product was a clear, hard resin, only soluble in highly polar organic solvents such as dimethylformamide and dimethylacetamide.

In another experiment, a polymer of dimethylolpropionic acid was prepared by heating a mixture of 1072 parts of dimethylolpropionic acid, 118 parts of xylene and 2 parts of methanesulfonic acid in a vessel equipped with a stirrer and Dean &amp; Stark cooler. The temperature was maintained at 150 ° C while esterification water was removed. The polymer precipitated out of solution as it formed. The reaction was stopped when 130 parts of water was removed and the acid number of the resin dropped to 21 mg KOH / g resin. The polymer was a hard glassy resin soluble in dimethylformamide.

Example 2

This example describes the preparation of a copolyester of dimethylolpropionic acid and 12-hydroxystearic acid.

402 parts of dimethylolpropionic acid, 900 parts of 12-hydroxystearic acid, 145 parts of xylene and 2.6 parts of methanesulfonic acid were charged into a vessel equipped with a stirrer, thermometer and water separator. The mixture was heated and the temperature maintained at 150 ° C for 8 hours. A total of 110 parts of water was removed during this time. The product was a low viscosity solution with 85% resin content in xylene with an acid number of 33 mg KOH / g and a hydroxyl number of 93 mg KOH / g.

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Example 5

This example describes the preparation of a copolyester of trimethylolacetic acid and 12-hydroxystearic acid.

600 parts of 12-hydroxystearic acid, 150 parts of trimethylolacetic acid, 89 parts of toluene and 75 parts of zirconium naphthenate (10 hours of metal content) were introduced into a flask equipped with a stirrer and water separator. The reaction mixture was heated and kept under reflux at a temperature of 160-170 ° C. During the initial stages of the reaction, the product solidified to a semi-crystalline solid upon cooling, but as the condensation proceeded, the product changed to a clear viscous liquid. The final product was a light yellow polymer solution with 84 $ resin solids in toluene. The acid number of the polymer was 24 mg KOH / g. Example 4

This example describes the preparation of an air-drying polyester from dimethylolpropionic acid and linseed fatty acid.

A vessel equipped with a stirrer, thermometer and water separator was charged with 806 parts of dimethylol propionic acid, 420 parts of linseed fatty acid, 123 parts of xylene and 12.3 parts of zirconium naphthenate (10 $ metal content). The mixture was heated and refluxed at a temperature of 160 ° C for 11 hours, during which time the acid number dropped to 20 mg KOH / g resin and the hydroxyl number to 150 mg KOH / g resin. The product was at this stage a clear, highly viscous resin solution with a content of non-volatile constituents of 90%. An additional 1035 parts of linseed fatty acid and 100 parts of xylene were added and the reaction was continued for an additional 8 hours. The acid number had dropped to 20 mg KOH / g resin, showing that essentially the entire amount of linseed fatty acid was esterified. The product was a low viscosity solution with a resin content of 90%.

Sufficient cobalt naphthenate and lead naphthenate solutions were added to a sample of the resin solution obtained in accordance with the above without further dilution to give a content of 0.1% Co and 1% Pb, calculated as metal on resin solids. This sample dried, as it was coated on glass in the form of a 100 µm film, over the course of 12 hours into a tough, rubbery, solvent-resistant film.

Example 5

This example describes the preparation of a thermosetting coating composition.

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A. Preparation of Polyester from Dimethylol Propionic Acid and

12-hydroxystearic acid.

726 12 parts hydroxistearic acid, 134 parts dimethylolpropionic acid, 95 parts xylene and 8.6 parts zirconium naphthenate (10% metal content) were reacted in a similar manner as described in Example 1 to form a polyester A having an acid number of 25 mg KOH / g and a hydroxyl number of 61 mg KOH / g in the form of an 88% solution in xylene.

B. Preparation of Polyester / Glycidyl Methacrylate Adduct.

600 parts of the polyester solution from A, 40.2 parts of glycidyl methacrylate, 0.5 parts of commercially available dimethyl derivative of C 1-6 alkylamine (ArmeenDMCD) and 0.15 parts of hydroquinone were introduced into a flask equipped with a stirrer and heated at temperature of 130-140 ° C for 3 hours. By this time, the acid number had dropped to 0.15 mg KOH / g resin, showing that substantially all of the terminal carboxylic acid groups in the polyester had reacted with the epoxide ring in the glycidyl methacrylate. The solids content of resin in this polyester / glycidyl methacrylate adduct B solution was 51%.

C. Preparation of Addition Copolymer / Polyester.

500 parts of toluene were introduced with stirring into a heated vessel and a mixture containing 500 parts of polyester / glycidylmethacrylate adduct B solution, 100 parts of methylmethacrylate, 100 parts of styrene, parts of ethyl acrylate and 7&gt; 5 parts of azo-isobutyronitrile was fed into it. refluxing toluene over the course of 1 hour. The heating was continued for another 2 hours to complete the polymerization. The final composition C had a polymer solids content of 39 parts of this polymer solution mixed with 1 part of a 50% solution of butylated melamine / formaldehyde resin. A 50µ thick film, stretched on glass, was baked at a temperature of 127 ° C for 30 minutes to give a clear, tough, tough, abrasion resistant film which was insoluble in ordinary solvents.

D. Preparation of thermosetting paint

A white pigment roll base was prepared by dispersing 15 parts of polyester / acrylic / styrene copolymer solution C, 70 parts of titanium dioxide and 18 parts of xylene in a mill with sand as a grinding aid until the dispersion had a particle size less than 5 microns according to the Hegemann scale . In a mixing vessel containing 20.5 parts of a 50% solution of a butylated melamine / formaldehyde resin in xylene and butanol, 30 parts of white pigment roller base, 44 parts of polyester / acrylic / styrene copolymer solution C were slowly added with stirring. , 0.2 parts 2% silicone oil solution in xylene, 4 parts butanol and 5 parts of a 3: 1 mixture of xylene and butahole ^:The above mentioned - the dye was diluted with xylene at a ratio of 5 · 1 and sprayed onto primed panels, which were then roasted for 30 minutes at a temperature of 127 ° C. A hard, shiny, solvent resistant coating was obtained. Example 6

This example describes the preparation of an air-drying polyester.

A. Preparation of Carboxyl-Finished Polyester

In a vessel equipped with stirrer, water separator and reflux condenser, 6000 parts of 12-hydroxystearic acid, 1330 parts of dimethylpropionic acid, 73 parts of zirconium naphthenate ($ 10 metal content) and 500 parts of mineral turpentine were introduced. The temperature was raised to 160 ° C and, under reflux, 434 g of water was removed over the course of 7 hours as the reflux temperature rose to 180 ° C. The resulting carboxyl terminated polyester A had an acid number of 34 mg KOH / g and the solids content of the product was 89

B. Preparation of polyester with terminal, ethylenically unsaturated group.

7163 parts of a solution of polyester A (solids content $ 89), 733 parts of glycidyl methacrylate, 7 parts of a commercially available dimethylamide of a C C ^ ^ fatty acid (Armeen DMCD) and 3.5 parts of hydroquinone were heated at a temperature of 150 ° C for 34 hours. The product had an acid number of 0.35 mg KOH / g, a hydroxyl number of 115 mg KOH / g and a solids content of 87.5 $.

C. Preparation of Additive Polymer / Polyester.

Copolymerization of methyl methacrylate with macromonomer B at a weight ratio of 1: 0.26 using azo-diisobutyronitrile (ADIB) as the initiator.

1650 parts of ethyl acetate were introduced into a vessel, provided with stirrer and reflux condenser, under nitrogen. Charge, one was heated to 78 ° C (reflux) and over the course of 3 hours was added at a steady rate 926 parts of methyl methacrylate, 482 parts of the 87.5% solution of B and 27 parts of ADIB. The temperature was then kept at 82 ° C for an additional 3 hours. The resulting polymer solution C had a solids content of 41.0%. This polymer was then esterified with tall oil fatty acids as follows.

D. esterification.

In a vessel equipped with a stirrer and water separator, 2888 parts of polymer solution C with a solids content of 4%, 237 parts of tall oil fatty acid, 7 parts of zirconium naphthenate and 150 parts of mineral turpentine were introduced. The temperature was raised to 200 ° C, ethyl acetate was evaporated to ensure that this temperature was reached and the reflux heating was continued for 8 hours, during which time 15 g of water was removed. The resin D was then cooled and diluted with ethyl acetate to a solids content of 46.1%.

To a sample of resin D, cobalt naphthenate solution was added in an amount to give 0.05 µg of cobalt metal, based on resin solids, and a film with a thickness of 100 µ was applied to glass. A hard, tough, flexible film is obtained by air drying at room temperature. After 24 hours of drying, the film had good resistance to xylene.

Example 7

This example describes the preparation of a segment polymerisate of a hydroxyl-containing polyester and an epoxy resin.

A polyester was prepared similarly to Example 1 from dimethylpropionic acid and 12-hydroxystearic acid in a 1: 1 molar ratio. 1055 parts of polyester (80% solution), 700 parts of Epikote 1004 (a commercially available epoxy resin having a molecular weight of 1400 and an equivalent weight of 175), 1345 parts of cellulose acetate and 15 »5 parts of Army DMCD were heated under reflux at 150 ° C. 5 hours. The acid number of the product had then dropped to 0.2 mg KOH / g resin as a result of the reaction between the terminal carboxylic acid group in the polyester and the epoxy resin.

A mixture of this product with a melamine / formaldehyde resin ratio of 3: 1 »segment polymeric resin: melamine / formaldehyde resin, applied as a 100 µ thick film on glass and baked in the oven for 30 minutes at a temperature of 150 ° C, gave a clear, hard, bridged film.