DE2450785A1 - VINYL CHLORIDE COPOLYMERISATES CONTAINING HYDROXYL GROUPS - Google Patents

Description

BASF Aktiengesellschaft

Our reference: O.Z. 30 931 Dd / Ri 67OO Ludwigshafen, October 24, 1974

Vinyl chloride copolymers containing hydroxyl groups

The invention relates to binders based on hydroxyl-containing binders Vinyl chloride copolymers of uniform chemical composition.

All kinds of vinyl chloride polymers have long been used used as a paint binder. Paint films made from it are characterized by good weather resistance, chemical resistance, Water resistance and advantageous mechanical behavior.

Vinyl chloride homopolymers are inadequate mainly because of their Solubility in the usual paint solvents not very suitable. By polymerizing comonomers ^ solubility and additional properties, such as compatibility with other paint resins, adhesive strength, softening point, crosslinkability and pigment binding capacity can be influenced in the desired direction.

Copolymers of vinyl chloride with vinyl esters, maleic acid esters, (Meth) acrylic acid esters, allyl esters and vinyl ethers are known. These polymers do not contain any reactive groups, so they can only form physically drying paint films. That Pigment dispersibility is often insufficient.

Vinyl chloride copolymers with reactive hydroxyl groups, which are used for crosslinkable paint films, are also known can. These copolymers are either by partial saponification of vinyl chloride / vinyl ester copolymers or by Polymerization of hydroxyl-containing monomers produced. The former method requires one in addition to polymerization

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further complex process step, namely that of the targeted partial saponification. The resulting products are often yellow in color and have little resistance to aging.

Hydroxyl-containing monomers copolymerizable with vinyl chloride are, for example, unsaturated alcohols, hydroxyalkyl vinyl ethers and Hydroxyalkyl (meth) acrylic acid esters. Such polymers are preferably modified with a further comonomer so that one can hydroxyl-containing vinyl chloride terpolymers. Terpolymers with vinyl esters, such as vinyl acetate and vinyl versatate, are known or with vinyl ethers such as methyl vinyl ethers and Butyl vinyl ether. Such terpolymers have the disadvantage that Their solutions in the usual paint solvents can usually only be mixed with hydrocarbons, such as gasoline, to a small extent are or that good blending only with relatively high comonomer contents is attainable.

The invention relates to binders based on a hydroxyl group Vinyl chloride copolymers with a Pikentscher K value between 30 and 60, characterized by the following Composition:

50 to 90 wt. # Vinyl chloride,

5 to 40 wt.% Of a hydroxyalkyl (meth) -acrylats having 2 to 4

Carbon atoms in the alkyl radical,
5 to 40 GeMi. % Of tert.-Butyl (meth) acrylate, and 0 to 10 wt.% Of further comonomers.

Possible hydroxyalkyl (meth) acrylate with 2 to 4 carbon atoms in the alkyl radical are: hydroxypropyl (meth) acrylate, hydroxyethyl (meth) acrylate, butanediol mono (meth) acrylate. Gegenenenfalls may contain from 0 to 10, preferably 0.5 to 5 wt.% Of further comonomers, such as, B. Glycidyl esters of unsaturated carboxylic acids, as well as unsaturated carboxylic acids such as acrylic acid, crotonic acid, maleic acid, fumaric acid, etc. are polymerized. The glycidyl groups have a stabilizing effect on the copolymer; the carboxyl groups can contribute to the use.

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Terpolymers are preferably from 70 to 85 wt.% Vinyl chloride ^ 5 to 25 wt.% Hydroxypropyl acrylate, and 5 to 25 wt.% Of tert, butyl acrylate.

The vinyl chloride terpolymers are produced according to the usual methods of radical polymerization. This is how they are obtained by mass, precipitation, solution or suspension polymerization, preferably by polymerization in aqueous emulsion.

The usual peroxide compounds such as benzoyl peroxide, lauroyl peroxide, tert-butyl perpivalate, diisopropyl peroxide carbonate or other peroxide compounds such as ammonium or potassium persulphate and hydrogen peroxide or diazo compounds such as azobisisobutyronitrile can be used as catalysts. The polymerization temperature is generally between 20 ° and 120 ⁰ C, preferably between H0 ° and 80 ° C.

In the case of emulsion polymerization, the usual anionic emulsifiers are used in amounts of 0.5-5 % . Examples include: alkyl sulfonates, aryl sulfonates and alkyl sulfates. It is particularly advantageous to use oxethylated sulfated phenols, alcohols or amides, such as, for example, oxethylated, sulfated iso-octylphenol (9-40 moles of ethylene oxide to 1 mole of phenol). The emulsion is expediently buffered with a suitable pH buffer such as sodium pyrophosphate, sodium acetate and others. In this way, polymers which are particularly clear and soluble without swelling bodies are obtained. The preferred mode of operation is the emulsion feed, ie a monomer emulsion is prepared, a portion is initially introduced, and polymerized by adding all or part of the catalyst and bringing the temperature to the desired polymerization temperature, and the remaining emulsion is run in portions or continuously , optionally together with the remaining amount of catalyst ,, during the polymerization. In this way a very uniformly copolymerized product with a narrow molecular weight distribution and good solubility is obtained.

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You can also use the so-called. Use seed latex driving mode, in which up to 5 l of a finely divided vinyl chloride / hydroxypropyl acrylate polymerization for template and polymerized. This gives coagulate-free dispersions.

But you can also submit all of the vinyl chloride and some of the comonomers in the aqueous phase and the remainder Add amount of comomomer as monomer feed during the polymerization according to the current conversion.

The polymerization can also be carried out in organic liquids in which the polymer is soluble or insoluble. Aliphatic (e.g. butane, pentane, hexane, etc.) and aromatic (e.g. benzene, toluene, xylene) hydrocarbons or alcohols such as methanol or ethanol are possible non-solvents for the polymer (provided it contains at least 75 % vinyl chloride). For solution polymerization, ketones such as acetone and methyl ethyl ketone, esters such as methyl acetate and ethyl acetate or ethers such as dioxane and tetrahydrofuran are suitable.

The polymer solutions obtained in the polymerization in solution can optionally be precipitated with nonsolvents or else Degassing extruders are worked up to solid products. In the case of polymerization in emulsion, the polymer must be isolated as such , expediently by precipitation. The usual reagents can be used as precipitants, such as salts one, two or trivalent metals or water-miscible solvents such as alcohols. In the case of the use of ethoxylated sulfated Phenols, alcohols or amides as emulsifiers are preferably used such water-soluble organic cationic compounds, the one with the related emulsifiers form water-insoluble complex. These are ammonium salts dated

Type ^ ₁ R ₂ ^R 3 ^R 4 ^M 3 ^X ° » ^where

a) R ₁ s H, R ₂ R, Rjj = alkyl (C ₁ -C ₁ Q) and / or aryl;

b) R ₁ R ₂ R ₃ R ₄ = alkyl (C ₁ -C ₁₈ );

_ Ej _

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c) R ₁ = benzyl-, R ₂ R ₃ Rj ₄ = alkyl (C ₁ -C ₁₈ );

d) R ₁ , R ₂ = benzyl, R ₃₅ R ^ = alkyl (C ₁ -C ₁₈ );

e) R ₁ = phenyl, R ₂ = benzyl, R ₃ , R ₁₄ = alkyl (C ₁ -C ₁₃ ) and

each X = Cl, SOj ₄ =, CH, SO ^ "" can be. In addition, alkyl or alkaryl pyridinium salts with alkyl = C ₁ -C ₁₈ can also be used. The plague products obtained in this way are free of metal ions and are clear and soluble without swelling bodies.

The polymers are expedient with the customary stabilizers for PVC, stabilized like epoxy compounds or organotin compounds. This can be done during the polymerization, e.g. by Polymerization of glycidyl esters of unsaturated carboxylic acids, e.g. glycidyl acrylate or subsequently by adding a stabilizer happen to the polymer solutions or in the processing to the pest product during or after the precipitation; or the stabilizer is added to the already dried plague product.

The molecular weight or the K value of the terpolymer according to the invention can be varied within wide limits. Under the usual polymerization conditions in Emulsion K-values can be (measured according Pikentscher in l ^ strength cyclohexanone solution at 25 ⁰ C) of 60 is obtained. However, the K value can be reduced to 30 by taking appropriate measures such as increasing the temperature or adding a regulator. The polymers according to the invention preferably have K values between 35-45.

The terpolymers according to the invention are distinguished by good properties Solubility in the known paint solvents such as ketones and esters. The following are particularly suitable: methyl ethyl ketone, Methyl isobutyl ketone, butyl acetate, ethyl glycol acetate, etc. Particularly The advantage is that these polymer solutions can be easily blended with cheap aliphatic and aromatic hydrocarbons. ' The viscosity can be adjusted in a targeted manner through the choice of the amount of the copolymers. The polymer solutions are of low viscosity, swelling body

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free and stable in storage. The polymers are versatile with others Coating resins such as melamine resins, urea-formaldehyde resins or other vinyl chloride copolymer resins.

In the case of polymerized carboxyl groups, curing can take place purely thermally; however, conventional crosslinking agents are preferred, such as polyisocyanates of the Desmodur L or N type added.

Sufficient crosslinking takes place at room temperature. The binders according to the invention form good clear coatings Adhesion strength and high mechanical level on various substrates, such as wood or metals, they also have a good one Pigment dispersion and carrying capacity. In their versatility, they surpass the usual commercial products.

example 1

A polymer according to the invention is prepared in the following manner: In a stirred autoclave flushed with nitrogen, 1500 parts of vinyl chloride, 28 parts of hydroxypropylene acrylate and 9 parts of t-butyl acrylate are converted into an aqueous solution of 12,000 parts of water, 54 parts of a solution ethoxylated with 25 moles of ethylene oxide and then sulfated Isooctylphenol and 36 parts of sodium acetate are added. The monomer emulsion is heated to 70 ⁰ C, where the inerts are removed (initial pressure 10 - 11 bar) and mixed with 720 parts of a 2% potassium persulfate. The polymerization is carried out up to a conversion of 10 % and the uniform feed of a monomer emulsion of 12,000 parts of water, 198 parts of sodium acetate, 294 parts of the above-mentioned emulsifier, 8,830 parts of vinyl chloride, 1,485 parts of hydroxylpropyl acrylate and 495 parts of t- Butyl acrylate. The feed rate depends on the rate of polymerization. Synchronous with the emulsion feed, 2,000 parts of a 2% potassium persulfate solution in water are added. Under the conditions mentioned in the example, the emulsion feed is ended after about 9 hours. The pressure gradually falls to

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7-8 bar. The mixture of 121 parts of hydroxypropyl acrylate and 40 parts of t-butyl acrylate is then run in over a period of 1 hour and about Ί h post-polymerized to a final pressure of 4 bar. After letting down the pressure and cooling, an approx. 30 # strength, finely divided dispersion with a pH of 4-5 results.

To work up the solid product, the dispersion is diluted to 10% and 150 parts of this dispersion are precipitated with 1.7 parts of a 20% strength aqueous solution of a dimethyl palm kernel fatty amine quaternized with benzyl chloride. Brief sintering at 80 ^° C. gives a fine-grained product that can be easily washed out and dried. The polymer contains 80 % vinyl chloride and has a Fikentscher K value of 39.

If you take samples during the polymerization and determine their Composition and K value, the measured values vary only slightly around the final values achieved for the product, proof of the Uniform structure of the copolymer over the entire course of the polymerization:

Sample 1 2 '3 4 5 Final sample

VC content 78.7 % 79.4 % 79.7 % 79.9 % 80.3 % 80.0

K value 39.5 38.1 38.9 39.4 39.1 39.0

Example 2

A copolymer is produced as in Example 1. Before precipitation, the dispersion, diluted to 10%, is admixed with a pre-emulsified mixture of 500 parts of water, 30 parts of an epoxidized soybean oil and 0.6 part of the emulsifier used in the polymerization. In this way, the stabilizer is distributed very evenly in the polymer.

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Example 3

A polymer containing polymerized stabilizing groups is prepared in the same way as under 1. The initial charge is composed of the aqueous phase, 1,500 parts of vinyl chloride, 18.5 parts of hydroxypropyl acrylate, 14.8 parts of t-butyl acrylate and 3 parts of glycidyl methacrylate . The emulsion feed is composed of the aqueous phase, 8,830 parts of vinyl chloride, 990 parts of hydroxypropyl acrylate, 792 parts of tert-butyl acrylate and 198 parts of glycidyl methacrylate. The polymerization proceeds as described in Example 1. After the end of the emulsion feed, a mixture of 80 parts of hydroxypropyl acrylate, 60 parts of t-butyl acrylate and 16 parts of glycidyl methacrylate is added and polymerized to completion. The work-up is carried out as described under The polymer contains 79 % vinyl chloride and has a K-Wfert according to Fikentscher of 37.5.

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Claims (5)

- 9 - O.Z. 30,931 claims 1. Binder based on a vinyl chloride copolymer containing hydroxyl groups with a K value between 30 and 60, characterized by the following composition 50 to 90% by weight vinyl chloride, 5 to 40% by weight of a hydroxyalkyl (meth) acrylate with 2 to 4 Carbon atoms in the alkyl radical, 5 to 40 wt.% Of tertiary butyl (meth) acrylate, and 0 to 10 wt.% Of further comonomers. 2. A binder according to claim 1, gekennz eichn et d urch following composition 70 to 85% vinyl chloride by weight., 5 to 25 wt.% Hydroxypropyl acrylate, 5 to 25 wt.% Tert-butyl acrylate. 3. A binder according to claim 1, characterized geken nzei seframe that the K-value is 35 to the 45th 4. Binder according to claim 1, dadurc h ^ indicates that the copolymers are prepared in aqueous emulsion. 5. Binder according to claim 1, characterized in that oxyethylated sulfated phenols, alcohols or amides are used as anionic emulsifiers in the preparation of the copolymers in aqueous emulsion, and cationic organic, water-soluble compounds are used to precipitate the polymer. BASF Aktiengesellschaft 609819/0995