DE3418524A1 - Process for preparing coating binders and the use thereof - Google Patents

Abstract

The invention relates to a process for preparing coating binders by suspension polymerisation of a monomer mixture of (A) methyl methacrylate, vinyl aromatics, alpha -methyl styrene and/or acrylonitrile and (B) at least one ester of acrylic acid with a monoalcohol containing 1 to 4 carbon atoms or of methacrylic acid with a monoalcohol containing 2 to 4 carbon atom and (C) one or more copolymerisable, olefinically unsaturated organic compounds containing 3 to 10 carbon atoms and which contain at least one carboxyl group or carboxylic acid anhydride group and, if appropriate, (D) further copolymerisable, olefinically unsaturated organic compounds, with, after a 10 to 90% conversion of the suspension polymerisation, an aqueous emulsion of a monomer the homopolymer of which has a glass transition temperature of above 40 DEG C being added, and polymerisation being completed. The coating binders obtained are suitable for preparing physically drying coating materials.

Description

Process for the production of lacquer binders and their use

The present invention relates to a method for producing Varnish binders by suspension polymerization, in which the advanced polymerization stage those monomers are added whose homopolymer has a glass transition temperature according to DSC of over 40 "C, as well as the use of these polymers for coating and impregnating agents.

The preparation of suspension polymers in the presence of by Dispersions prepared by suspension polymerisation are described in NE-PS 66 17 307 and in BE-PS 634 722 described. This creates pearl-shaped products in which only the monomers of the first polymerization step are represented, and im Following this, pearl-shaped products are created, in which only the monomers of the second Polymerization step are represented. If you want a bead polymer, the one has a sticky surface, cover it with a harder polymer layer, so it works This is not the case if the monomers required for this are only used after 100% conversion of the polymer formed in the first stage is added. Another disadvantage of the known process of the stepwise copolymer production is that the The polymer formed in one stage has the solubility properties of the other Stage formed polymer significantly deteriorated. If you add the monomers the first and second polymerization stage and leads with the monomer mixture If the sum of only one polymerization step is carried out, the solubility properties deteriorate of the formed product, and the pigment wettability is also not satisfactory.

The present invention was therefore based on the object of a method for the production of lacquer binders by suspension polymerisation, in which one obtains tack-free pearls that have good solubility in aromatic solvents own. Furthermore, the white spirit should be blended into aromatic solutions Solvents are given and the products should have good pigment dispersibility as well as improved mechanical properties of the coatings obtained therewith.

The present invention relates to a method of production of paint binders through suspension polymerization of a monomer mixture (A) 30 to 80% by weight of methyl methacrylate, vinyl aromatics, oG-methylstyrene and / or acrylonitrile, and (B) 20 to 70 Gew.Z at least one ester of acrylic acid with a monoalcohol containing 1 to 4 carbon atoms or methacrylic acid with a monoalcohol containing 2 to 4 carbon atoms, as well as (C) O to 10 % By weight of one or more copolymerizable olefinically unsaturated 3 to 10 Organic compounds containing carbon atoms which contain at least one carboxyl or contain carboxylic acid anhydride group and (D) O to 30 wt. X further under (A) to (C) not mentioned copolymerizable olefinically unsaturated organic Compounds, where the sum of the percentages mentioned under (A) to (D) - 100 which is characterized in that at a conversion of the suspension polymerization from 10 to 90% an aqueous emulsion containing 1 to 16 percent by weight of at least one monomer, the homopolymer of which has a glass transition temperature of over 40 ° C., preferably Methyl methacrylate, styrene, cC-methylstyrene and / or acrylonitrile, based on the Sum of the monomers (A) to (D), contains, is added and then polymerized to the end will.

The present invention also relates to the use of the suspension polymers produced according to the invention for the production of physically drying coating or impregnation materials.

The suspension polymers produced by the process according to the invention are characterized by good flowability and, at the same time, surprisingly due to good solubility in e.g. aromatic solvents, good blending properties these solutions with white spirit and a good pigment dispersibility.

Regarding the structural components of those produced and used according to the invention Copolymers are to be carried out in detail as follows: (A) As component (A), the Can be used in amounts of 30 to 80, preferably 40 to 60% by weight Methyl methacrylate, vinyl aromatics such as styrene, Ct-methylstyrene, acrylonitrile or mixtures of these monomers can be used. Methyl methacrylate and styrene are preferred.

Methyl methacrylate in amounts of 40 to 60 is particularly preferred Weight%.

(B) As component (B), esters of acrylic acid with 1 to 4 carbon atoms containing monoalcohol or ester of methacrylic acid with 2 to 4 carbon atoms containing monoalcohol, such esters with straight-chain or branched ones are suitable Monoalcohols, e.g. methyl acrylate, ethyl acrylate, n- and iso-propyl acrylate, n- and iso-butyl acrylate, tert-butyl acrylate, ethyl methacrylate, n- and iso-propyl methacrylate, n- and iso-butyl methacrylate and tert-butyl methacrylate or mixtures thereof. component (B) is in the monomer mixture to be used according to the invention in amounts of 20 to 70, preferably 40 to 60 wt.% Contain. Preference is given to n-butyl acrylate, iso-butyl acrylate, tert-butyl acrylate, ethyl methacrylate, iso-butyl methacrylate and tert-butyl methacrylate. Isobutyl methacrylate and isobutyl acrylate either alone are particularly preferred or a mixture of the two in amounts of 45 to 55% by weight.

(C) As component (C), copolymerizable olefinically unsaturated Organic compounds containing 3 to 10 carbon atoms with at least one Carboxyl or carboxylic acid anhydride group can be used, such as acrylic acid, Methacrylic acid, maleic acid, itaconic acid or the anhydrides or half esters of these Dicarboxylic acid. For the preparation of the half-esters, 1 to 8 carbon atoms can be used Alcohols or glycol ethers can be used, such as ethanol, isopropanol, butanol or butyl glycol. Component (C) can be used in the monomer mixture to be used according to the invention Can also be used in amounts of 0 to 10% by weight. Maleic acid half esters are preferred. Maleic acid monobutyl ester is particularly preferred in amounts of 0.5 to 4% by weight.

(D) The component (D) is another one under (A) to (C) not mentioned copolymerizable olefinically unsaturated compounds which Can also be used in amounts of 0 to 30% by weight. These are, for example Mono (meth) acrylates of C1 to C8 alkane diols such as hydroxyethyl and hydroxypropyl (meth) acrylate as well as butanediol mono (meth) acrylate or (meth) acrylamide. As component (D) can For example, vinyl alkyl ethers with 2 to 8 carbon atoms may also be present in the Alkyl radical, vinyl esters of carboxylic acids with 2 to 8 carbon atoms, diesters of maleic acid, Itaconic acid, citraconic acid or mesaconic acid with optionally ether or thioether groups containing monoalcohols with 1 to 20 carbon atoms. In a preferred embodiment component (D) is not used in accordance with the invention.

The suspension polymerization is carried out according to methods known per se, for example as in High Polymers - A Series of Monographs on the Chemistry, Physics and Technology of High Polymeric Substances - Vol. XXIX, pp. 106 to 142 described, carried out. As initiators, for example, benzoyl peroxide, Azobisisobutyronitrile, tert-butyl peroctoate or lauroyl peroxide can be used. The initiators can be dissolved in the monomers or as an emulsion or suspension be added in water. A suspension of benzoyl peroxide or is preferred Lauroyl peroxide used in water. The amounts of initiator are generally 0.5 to 5% by weight, preferably 1 to 3% by weight. The initiator feed is generally within 1 to 8 hours, preferably 2 to 6 hours of the aqueous monomer suspension added. After the end of the initiator feed, the process is continued for a further 2 to 10 hours post-polymerized at the selected polymerization temperatures to show a 100 To achieve conversion of the copolymer.

As protective colloids for suspension polymerization, the commonly used water-soluble polymeric substances, for example polyvinylpyrrolidone, preferably use (R) Luviskol K 90.

If the conversion of the suspension polymerization is 10 to 90 Z, will an aqueous emulsion of at least one monomer, the homopolymer of which has a glass transition temperature of over 40 "C, preferably methyl methacrylate, styrene, oC-methylstyrene and / or acrylonitrile added. The amount of added monomer or monomer mixture is 1 to 16, preferably 5 to 15% by weight, based on the sum of the monomers (A) to CD).

As emulsifiers for the aqueous emulsions of the added monomers can be long-chain carboxylic acid or sulfonic acid salts or the salts of sulfonated ones Condensation products from e.g. isooctylphenol and approx.

25 moles of ethylene oxide are used. Other suitable emulsifiers are described in H. Stache, Tensid-Taschenbuch, Carl Hanser-Verlag 1979.

The subsequently metered aqueous emulsion contains 10 to 40% by weight, preferably 20 to 30 percent by weight of monomers. The monomer emulsion is when the suspension polymer is converted from 10 to 90%, preferably 50 to 80%, added. That is particularly preferred Addition of the monomer emulsion during the last third of the initiator feed Suspension polymerization.

This production process gives free-flowing perpolymers, which are uncrosslinked and generally have an average molecular weight between 2000 and 50,000, preferably 5,000 to 40,000 (measured with a vapor pressure osmometer) own. The Fikentscher K values (measured 3 cents in acetone) are accordingly between 20 and 40, preferably between 30 and 38.

The solution of the suspension polymers in aromatic solvents such as w olvesso 100 is free from insoluble polymers and has an opposite a non-replenished polymer unchanged white spirit blendability.

The suspension polymers prepared according to the invention are suitable for example as a binder for physically drying from organic solution Coating and impregnating materials.

The usual additives for such coating and impregnation materials, such as pigments, fillers, plasticizers, wetting agents and solvents can be used in be incorporated in a known manner.

Furthermore, the binders produced according to the invention can with other compatible lacquer binders in a manner known per se, for example by mixing in the form of their binder solutions. Compatible Examples of binders are vinyl chloride copolymers, chlorinated rubber and others Methacrylic acid polyester. The weather resistance of coatings on the The basis of chlorinated rubber and vinyl chloride copolymers can be combined improve significantly with the paint binders produced according to the invention.

The following examples are intended to be the subject of the present invention explain in more detail without restricting it. The parts given in the examples Unless otherwise stated, percentages relate to weight.

I. Preparation of the polymers Example 1 In a glass vessel with 3-stage impeller stirrer, internal thermometer and reflux condenser are 9,800 parts Water, 5 parts of sodium thiosulphate and 42.5 parts of 10% aqueous Luviskol K 90 t = Submitted polyvinylpyrrolidone with K value 90) solution. Then you give a mixture from 1200 parts of methyl methacrylate, 570 parts of isobutyl methacrylate, 675 parts of isobutyl acrylate, 50 parts of maleic acid monobutyl ester and 35 parts of tert-dodecyl mercaptan are added. First, the mixture is dispersed for 15 minutes at room temperature with stirring (550 revolutions / min). Then it is heated to an internal temperature of 750C. When the internal temperature 75 ° C. is reached, a mixture of 11 parts of lauroyl peroxide and 9 parts is added 10% aqueous Luviskol K 90 solution and 80 parts of water are added. 3 more of the same type Additions are made every 30 minutes. 15 minutes after the last An emulsion of 125 parts of methyl methacrylate is added within 30 minutes, 6.25 parts of an aqueous solution of an emulsifier (= the sodium salt of a sulfonated condensation product from isooctylphenol and approx. 25 mol of ethylene oxide) and 1000 parts of water. Immediately at the end of the feed, 11 parts of lauroyl peroxide, 9 parts of 10 goat aqueous Luviskol K 90 solution and 80 parts of water were added. 30th Minutes later, another 10 parts of lauroyl peroxide, 4.5 parts, are added 10 Xiger aqueous Luviskol K 90 solution and 40 parts of water. It will be another 4 hours Post-polymerized at 750C. It is then cooled and the finished polymer is filtered off and washed with water until the filtrate is clear. After drying of the product in the fluidized bed dryer, free-flowing beads with a solids content are obtained (2 hours, 125 "C) of 99.1 X, a K value (according to Fikentscher) of 35, an acid number CDIN 53 402) of 4.6 and a glass transition temperature of 46in. The glass transition temperature range is 330C. The viscosity of the 30 point solution of the polymer in Solvesso 100, measured as the flow time in the DIN cup 4 at 23 ° C. is 63 seconds. The solution of the polymer in Solvesso 100 is clear.

Example 2 The suspension polymer is prepared as in Example 1, only the emulsion feed in the post-polymerization phase consists of 250 parts of methyl methacrylate, 12.5 parts of a 35% strength aqueous solution of the emulsifier mentioned in Example 1 and 1000 parts of water. After drying the product in a fluidized bed dryer free-flowing beads with a solids content of 99.1% and a K value are obtained of 32.9, an acid number of 3.3 and a glass transition temperature of 46'C. Of the Glass transition temperature range is 31-C. The viscosity of the 30% solution of the polymer in Solvesso 100, measured as the flow time in the DIN cup 4 at 23 etc. is 45 seconds, the solution of the polymer in Solvesso 100 is clear.

Example 3 The suspension polymer is described as in Example 1 produced, only the emulsion feed in the post-polymerization phase consists of 375 parts of methyl methacrylate, 18.5 parts of an aqueous solution of the in Example 1 mentioned emulsifier and 1000 parts of water. After drying in a fluidized bed dryer free-flowing beads with a solids content of 99% and a K value are obtained of 34.9, an acid number of 4.9 and a glass transition temperature of 500C. Of the Glass transition temperature range is 30'C. The viscosity of the 30% solution of the polymer in Solvesso 100, measured as the flow time in the DIN cup 4 at 23 "C, is 52 seconds, the solution of the polymer in Solvesso 100 is clear.

Comparative Example 1 (without further addition of methyl methacrylate) The suspension polymer is prepared as described in Example 1, only on top-up with a Methyl methacrylate emulsion is not used. After drying in a fluidized bed dryer sticky pearls are obtained with a solids content of 99%, a K value of 34.5, an acid number of 4.9 and a glass transition temperature of 37 "C.

The glass transition temperature range is 47 "C. The viscosity of the 30% solution of the polymer in Solvesso 100, measured as the flow time in the DIN cup 4 at 23 "C, is 54 seconds, the solution in Solvesso 100 is clear.

Comparative example 2 (methyl methacrylate replenishment after 100% Conversion of the 1st stage) In a vessel with 3-stage impeller stirrer, internal thermometer and reflux condenser are 9800 parts of water, 5 parts of sodium thiosulfate and 42.5 parts Submitted parts of a 10% aqueous Luviskol K 90 solution. Then you give one Mixture of 1200 parts of methyl methacrylate, 570 parts of isobutyl methacrylate, 675 Parts of isobutyl acrylate, 50 parts of maleic acid monobutyl ester and 35 parts of tert-dodecyl mercaptan added. First, 15 minutes at room temperature with stirring (550 revolutions / min.) dispersed. Then it is heated to an internal temperature of 75 "C. When the internal temperature 75 ° C. is reached, a mixture of 11 parts of lauroyl peroxide and 9 parts is added 10% aqueous Luviskol K 90 solution and 80 parts of water are added. 4 more of the same type Additions are made every 30 minutes. It will be another 5 hours at 75 "C post-polymerized and then cooled to room temperature. The next day the The suspension is stirred up again and treated with a mixture of 375 parts of methyl methacrylate, 6.4 parts of a 10% strength aqueous Luviskol K 90 solution, 7.5 parts of lauroyl peroxide and 875 parts of water are added. It is heated to an internal temperature of 75 "C and It is polymerized for 7 hours at 75 ° C. It is then cooled and the finished polymer is filtered off and washed with water until the filtrate is clear. After the The product in the fluidized bed dryer gives free-flowing beads with a solids content of 98.9%, a K value (according to Fikentscher) of 31.9, an acid number of 4.8 and a glass transition temperature of 410C. The glass transition temperature range is 28 "C. The viscosity of the 30% strength solution of the polymer in Solvesso 100, measured as the flow time in the DIN cup 4 at 23 "C, is not sensible to measure, because the solution of the poly merisats in Solvesso 100 is very cloudy and insoluble Contains polymethyl methacrylate.

Comparative example 3 (one-step production of the total composition of Example 3) As described in Comparative Example 1, a suspension polymer produced, but the total composition is in contrast to the comparative example 1 from the sum of the monomers from Example 3: 1,575 parts by weight of methyl methacrylate 570 parts by weight of isobutyl methacrylate 675 parts by weight of isobutyl acrylate 50 parts by weight Maleic acid monobutyl ester is obtained after drying in a fluidized bed dryer pearls that are no longer free-flowing, with a solids content of 99.1%, a K value (according to Fikentscher) of 34.1, an acid number of 5.5 and 2 glass transition temperatures namely a low of 35 and a higher of 59 ° C. The glass transition temperature ranges are 24 and 22 ° C.

The viscosity of the 30% solution of the polyether in Solvesso 100, measured as the flow time in the DIN cup 4 at 23 ° C., is 71 seconds. The solution of the polymer in Solvesso 100 is clear.

Comparative example 4 (additional metering of 20% by weight of methyl methacrylate) The suspension polymer is prepared as described in Example 3, only the The emulsion feed of the post-polymerization phase consists of 500 parts of methyl methacrylate, 25 parts of a 35% strength aqueous solution of the emulsifier mentioned in Example 1 and 1000 parts of water. After drying in a fluidized bed dryer, free-flowing ones are obtained Pearls, with a solids content of 98.7%, a K value of 32.6, an acid number of 4.5 and 2 glass transition temperatures of 43 and 92 "C. The glass transition temperature ranges be 240C. The viscosity of the 30% solution of the polymer in Solvesso 100, measured as the flow time in the DIN cup 4 at 23etc, is not meaningfully measurable, because the solution is very cloudy and in Solvesso 100 insoluble polymethyl methacrylate contains.

II. Coating agents For the production of coating materials can the copolymers obtained according to Examples 1 to 3 in twice the amount a commercially available aromatic solvent (e.g. Solvesso 100) by stirring Clearly dissolved at room temperature and in a known manner, e.g. with rutile and barite be pigmented.

The solutions or colors obtained film on after application the substrate to be coated in the air through solvent evaporation.

A comparison of the pigmented coating agents (100 parts of copolymer / 280 parts Solvesso 100/60 parts rutile / 30 parts heavy spar) results in the same Drying time (24 hours at 23es) and the same dry film thickness (40 pm) for the Copolymer prepared according to Example 3 has a much higher film hardness than for the copolymer prepared according to Comparative Example 3.

Claims (4)

Claims 1. A method for producing paint binders by suspension polymerization of a monomer mixture from (A) 30 to 80 wt Methyl methacrylate, vinyl aromatics, i-methylstyrene and / or acrylonitrile and (B) 20 up to 70% by weight of at least one ester of acrylic acid with 1 to 4 carbon atoms containing monoalcohol or methacrylic acid with 2 to 4 carbon atoms containing monoalcohol and (C) 0 to 10% by weight of one or more copolymerizable olefinically unsaturated organic compounds containing 3 to 10 carbon atoms, which contain at least one carboxyl or carboxylic acid anhydride group and (D) 0 Up to 30% by weight of other copolymerizable olefinic polymers not mentioned under (A) to (C) unsaturated organic compounds, the sum of those mentioned under (A) to (D) Percentages is equal to 100, characterized in that with a conversion of the suspension polymerization from 10 to 90% an aqueous emulsion containing 1 to 16% by weight of at least one monomer, the homopolymer of which has a glass transition temperature of over 40 ° C., preferably Methyl methacrylate, styrene, OC-methylstyrene and / or acrylonitrile, based on the Sum of the monomers (A) to (D) contains, is added and then polymerized to the end will. 2. The method according to claim 1, characterized in that as a component (C) a maleic acid half-ester is used. 3. Use of the according to a method according to one of the preceding Claims produced binders for the production of physically drying Coating or impregnating materials. 4. Use of the according to a method according to any one of claims 1 or 2 prepared binders in combination with chlorinated rubber or vinyl chloride copolymers for the production of physically drying coating or impregnating materials.