DE1228357B - Aqueous stoving enamels - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

C09d

German class: 22 g-10/01

Number: 1228 357

File number: B61162IVc / 22g

Filing date: February 7, 1961

Opening day: November 10, 1966

The invention relates to stoving enamels for the production of very hard, transparent, smooth and light-colored Coatings on materials of the most varied types that are insoluble and resistant to water.

It is known to consist of soluble polymeric substances or mixtures of substances under certain conditions capable of forming insoluble products on their own or through interaction with one another are, based on solutions of the substances or mixtures of substances in organic solvents, insoluble Manufacture polymers on materials of all kinds. To do this, the solutions are left on generally drying the materials completely or partially and producing them by warming or heating, optionally in the presence of curing agents, d. H. Substances that chemical interaction of the solid components influence one another in the desired sense, the insoluble polymers. In this way you can z. B. varnish-like coatings, coatings, films, laminates, Produce impregnations, finishes and bonds. As starting materials for the process mentioned one has above all relatively high molecular weight, mostly water-insoluble condensation products of the Formaldehyde with phenolic substances such as phenol or cresol, as well as with urea, melamine, Guanidine or the derivatives of these nitrogen compounds are used. These so-called "phenoplasts" or »aminoplasts« are alone, mixed with one another and mixed with Alkyd resins are used, as are certain N-methylol groups or containing etherified N-methylol groups and also mostly water-insoluble, not polymers derived from urea, melamine or guanidine.

Since working with organic solvents is relatively expensive and occasionally other disadvantages brings with it, such as odor nuisance or the risk of fires, explosions and damage to health, attempts have also been made to remove insoluble, water-resistant polymers made of soluble, in particular water-soluble substances or Mixtures of substances in a manner similar to that already set out above, but starting from aqueous solutions, to create. One has for this on the one hand, instead of the already mentioned relatively high molecular weight, mostly only substances or mixtures of substances soluble in organic solvents, the corresponding monomers or Oligomers, provided they are water-soluble, used. On the other hand, you already have through the installation modified by carboxyl group-containing compounds, relatively high molecular weight water-soluble Aqueous stoving enamels

Applicant:

Aniline & Soda Factory in Baden

Aktiengesellschaft, Ludwigshafen / Rhein

Named as inventor:

Dr. Hans Wilhelm, Ludwigshafen / Rhine;

Dr. Eberhard Wegner, Frankenthal (Palatinate);

Dr. Karl Kohl,

Dr. Kurt Demmler, Ludwigshafen / Rhine

Polymers or polycondensates processed together with such water-soluble compounds, capable of reacting with carboxyl groups at an elevated temperature in order in the course of the application to obtain cross-linked, insoluble products. It has also been proposed to use polymers of acrylic or methacrylic acid amides and copolymers of these amides with acrylic or methacrylic acid and if necessary together with formaldehyde or precondensates of formaldehyde to use with phenoplasts or aminoplast-forming substances. Through these measures it is possible, from aqueous solutions, to materials of various kinds in water and organic Solvents to produce no longer soluble products. However, these are not always able to do this to meet all requirements, as some of them still swell in contact with water and some are relatively brittle and are mostly opaque as well as in the production of coatings with thicker layers tend to form cracks and wrinkles and often darken at higher temperatures. Because of The processes mentioned do not generally have these properties, particularly in paint technology can enforce.

It has now been found that insoluble, water-resistant, very hard, transparent, Smooth and bright finishes can be produced if one uses stoving enamels that are essentially consist of an aqueous or water-containing solution of a mixture of

A. about 40 to 90 percent by weight of at least one water-soluble copolymer

a) about 35 to 65 percent by weight acrylic acid

amide or methacrylic acid amide or a mixture of these two amides and

609 710/284

b) about 35 to 65 percent by weight of an ester of acrylic acid or methacrylic acid a monohydric, non-polymerizable alcohol or a mixture of such esters and

c) optionally and advantageously up to about 15 percent by weight of a monoester of acrylic acid or methacrylic acid with a dihydric or higher alcohol or a mixture of such esters and

d) optionally other monomeric copolymerizable compounds in subordinate Quantities and

B. about 10 to 60 percent by weight of at least one water-soluble phenoplast or one corresponding oligomers and

C. optionally and advantageously up to about 50 percent by weight of at least one water-soluble aminoplasts or a corresponding oligomer or monomer.

According to the invention, particularly suitable water-soluble copolymers (1) are those whose K value (according to H. Fikentscher, Cellulosechemie, 13 [1932], p. 58) is between 20 and 60 and the are produced by precipitation polymerization, especially by the method according to German Auslegeschrift 1195 050 and in particular that according to the method of the German Auslegeschrift 1150 526 produced water-soluble copolymers. For stoving enamels are particularly good such copolymers are suitable whose ester component (b) consists of ethyl acrylate or from ester mixtures containing at least about 50 percent by weight of ethyl acrylate among others Acrylic or methacrylic acid esters contain. To be considered as such are preferably the Methacrylic and especially the acrylic acid esters of methanol, n-propanol, i-propanol and tert-butanol and the monoesters (c) of ethylene glycol, propylene glycol (1,2), propylene glycol (1,3) and des Butanediols (1,4) and its isomers. Often it is also advantageous if the monomer mixture as Monomers (d) or as a partial replacement for the amide component (a) up to about 10 percent by weight on special amides, such as maleic acid, fumaric acid, itaconic acid diamide, crotonic acid amide, ring-shaped amides such as vinylpyrrolidone, vinylcaprolactam, contains. For example, according to the invention, the copolymers are composed of 55 percent by weight acrylic acid amide and 45 percent by weight of ethyl acrylate or 60 percent by weight of methacrylic acid amide and 40 percent by weight of ethyl acrylate or 50 percent by weight of acrylic acid amide, 25 percent by weight Butanediol monoacrylate and 25 percent by weight of ethyl acrylate or 55 percent by weight Acrylic acid amide, 35 weight percent acrylic acid ethyl ester and 10 weight percent acrylic acid tert-butyl ester very suitable for the production of lacquers.

Suitable phenoplasts (B) according to the invention are the customary resins or their oligomers composed of formaldehyde and phenolic substances such as phenol and cresol, provided they are water-soluble and at elevated temperature with carboxamide groups and optionally other reactive groups, e.g. B. hydroxyl groups are able to react. The production of such phenolic resins is z. B. in the book. by D, S. Gould, 5 '"Phenolic Resins" (1959), New York, Reinhold Publishing Co., or by K. Hultsch in "Chemie der Phenolharze" 1950), Springer-Verlag, Berlin.
As aminoplasts (c) are suitable according to the invention

ίο the usual ones, made from formaldehyde and certain nitrogenous Resins made up of substances or their oligomers and in some cases also the corresponding ones Monomers. Resins useful in accordance with the present invention can be e.g. More colorful Use of urea, thiourea, melamine, ameline, guanidine, dicyandiamide, glyoxalureides, such as glyoxal di- and monoureide, ethylene urea and substitution products and derivatives of gain mentioned connections. The production of such aminoplasts is z. B. in the book of J. F. Blais, "Amino Resins" (1959), New York, Reinhold Publishing Co., dealt with.

The inventive, from the polymer component (A), the phenoplast component (B) and if appropriate, the aminoplast component (C) prepared homogeneous, aqueous solutions should preferably about 10 to 40%> solids, but can, if desired, also higher or low-percentage solutions can be used. Sometimes it is advantageous to use the aqueous solutions Add water-miscible organic solvents, e.g. B. alcohols, ethers, ketones. Colored products can be obtained in a simple manner by adding pigments or soluble ones to the solutions Adding dyes. When processing to lacquer-like coatings, it is often expedient to use the Solutions Substances to improve the flow and film formation, such as glycol ether, Acetals, glycols, dimethylformamide, sulfones, sulfoxides, diacetone alcohol, to be added.

For the production of lacquer-like coatings from the aqueous solutions according to the invention, these can, for. B. be applied to wood, metal, plastic using the usual methods, such as spraying, brushing, pouring, rolling, flooding, dipping or soaking. By heating the objects treated in this way to temperatures between 100 and 230 ° C., preferably about 160 to 180 ° C., for a period of about 10 to 180 minutes, preferably 15 to 60 minutes, insoluble, water-resistant, very hard, transparent ones are made , smooth and bright products available.
"Furthermore, the solutions according to the invention can be used to impregnate other types of materials, for example fabric, fleece or paper, and then handle them at higher temperatures after drying. In this way, for example, impregnations or laminates can be produced by adding one or Bringing several layers of the materials treated with resin solution onto a substrate or laying them on top of one another and hardening them at an elevated temperature, possibly under pressure and deformation.

It is often expedient to cure the coatings in the presence of the resins containing methylol groups customary auxiliaries that have a beneficial effect on chemical hardening. Suitable auxiliaries of this type are mostly acidic reacting

bonds such as carboxylic acids or esters and salts of inorganic acids such as ammonium nitrate and Ammonium chloride.

From the following Aufstellunng the surprising effect of the invention is clear, the The problem was based on the large number of possible aqueous solutions for stoving enamels water-soluble polymers, polycondensates and polyaddates a particularly suitable two or two. Find the three-substance system. The solution to this task is made possible by the wide range of options made difficult by the fact that the reliable prediction of the properties of baked paints on Because of their starting materials is not possible. The following list also shows the surprising one Superiority of the paints according to the invention over paints based on the combination of Acrylamide copolymers with aminoplast condensates, which are from US Pat. No. 2,862,901 is known. The unexpectedly high resistance of the paints according to the invention to Water at room temperature for over 15 hours ίο compared to the resistance of an analogue one Painting with a combination of an acrylamide copolymer with an aminoplast condensate of less than an hour.

20% aqueous solution used as film former, the dry substance of which consists of

Mixed polymer 55 parts of acrylic acid amide
25 parts of ethyl acrylate
20 parts of n-butanediol monoacrylate Phenoplast Aminoplast from 55 parts of acrylic acid amide
30 parts of ethyl acrylate
10 parts of n-butanediol monoacrylate
5 parts of acrylic acid tert-butyl ester _ 1 part phenol
2 parts formaldehyde
condensed at 70 ° C Tetramethylol
glyoxaldiurein 100% - _ _ - - 100% - - - 100% 53% 35% 65% 53% 47% - - 47% - 57% 15% 28%

Properties of those obtained on glass plates surface behavior body ι coatings surface behavior Hardened for 40 minutes at 165 ° C against water against water (12 hours Cured at 200 ° C for 20 minutes (12 hours smooth at space hard smooth at space body colour wrinkled temperature) brittle wrinkled temperature) smooth inconsistent very brittle colour smooth inconsistent cracked something swells brittle cracked something swells hard bright smooth inconsistent very hard smooth inconsistent brittle dark smooth inconsistent very hard bright smooth inconsistent very brittle bright smooth inconsistent very hard dark smooth inconsistent brittle dark resistant dark resistant very hard bright resistant dark resistant very hard bright bright very hard bright light brown bright

The parts mentioned in the examples are parts by weight.

Example I.

40 parts of a 20% strength aqueous solution of a copolymer of 55 parts of acrylic acid amide are mixed, 30 parts of ethyl acrylate, 10 parts of butanediol monoacrylate and 5 parts of tert-butyl acrylate, produced by precipitation polymerization in n-butanol according to the German method Auslegeschrift 1150 526, prepared with 10.5 parts of a 20% strength aqueous solution of a phenolic resin by alkaline condensation of phenol and formaldehyde in a ratio of 1: 2 at 70 ° C and 20 parts of a 20% strength aqueous solution of tetramethylolglyoxaldiurein. This solution cancels is placed on a glass plate and, after the water has evaporated, heated to 165 ° C. for 40 minutes The film obtained in this way is very hard, bright, smooth and completely transparent. The hardness value measured with the Albert pendulum according to König, is 194 seconds. If the film is stored in water for 12 days, it remains he completely unchanged. The pendulum hardness is then 182 seconds.

Example II

40 parts of a 20% strength aqueous solution of a copolymer of 35 parts of acrylic acid amide are mixed, 20 parts of methacrylic acid amide, 35 parts of ethyl acrylate and 10 parts of butanediol monoacrylate, produced by precipitation polymerization in n-butanol according to the German method Auslegeschrift 1150 526, made with 11 parts of a 20% strength aqueous solution of a phenolic resin by alkaline condensation of phenol and formaldehyde in a ratio of 1: 2 at 70 ° C, as well as 22 parts of a 20% strength aqueous solution of tetramethylolglyoxaldiurein. If you delete this solution on a glass plate and heated to 160 ° C for 40 minutes after the water has evaporated you get a very hard, transparent, colorless film. The hardness value, measured with the Albert pendulum according to König by determining the decay time of the oscillation, is 196 seconds.

After 10 days of storage in water, the film is practically unchanged; the pendulum hardness is then 170 seconds.

Example III _fl

15 parts of a 20% aqueous solution are mixed Solution of a copolymer of 55 parts of methacrylic acid amide and 30 parts of ethyl acrylate and 15 parts of butanediol monoacrylate, prepared by precipitation polymerization in n-butanol according to the method according to German Auslegeschrift 1150 526, with 3.75 parts of a 20% aqueous Solution of a phenolic resin, produced by the alkaline condensation of phenol with formaldehyde in a ratio of 1: 2 at 70 ° C. This solution is painted on a glass plate and heated to 165 ° C for 20 minutes after the water has evaporated you get a smooth, colorless, transparent, very hard film. The hardness value, measured with the Albert pendulum according to König by determining the decay time of the oscillation is 226 seconds. After 10 days of storage in water, the film is practically unchanged and the pendulum hardness is then 202 seconds.

Example IV

15 parts of a 20% aqueous solution of a copolymer of 55 parts of acrylic acid amide, 25 parts of ethyl acrylate and 20 parts of butanediol monoacrylate, prepared by precipitation polymerization in n-butanol according to the method according to German Auslegeschrift 1150 526, are mixed with 5.6 parts of a 20 ° % aqueous solution of a phenolic resin, prepared by alkaline condensation of phenol and formaldehyde in a ratio of 1: 2 at 70 ° C., and 7.6 parts of a 20% aqueous solution of tetramethylolglyoxaldiurein. If this stoving varnish is painted on a glass plate, a very hard, colorless, transparent varnish is obtained after the water has evaporated and stoved at 165 ° C. in 40 minutes. The hardness value, measured with the König Albert pendulum by determining the decay time of the oscillation, is 198 seconds. After lltägiger storage in water, the coating is virtually -unverändert, then the pendulum hardness is 194 seconds. \ announce.

Claims (1)

Claim: Stoving enamels for the production of insoluble, water-resistant coatings, essentially consisting of an aqueous or water-containing solution of a mixture of A. about 40 to 90 percent by weight of at least one water-soluble copolymer the end a) about 35 to 65 percent by weight of acrylic acid amide or methacrylic acid amide or a mixture of these two amides and b) about 35 to 65 percent by weight of an ester of acrylic acid or methacrylic acid with a monohydric, non-polymerizable alcohol or a mixture such ester and c) optionally and advantageously up to about 15 percent by weight of a monoester of acrylic acid or methacrylic acid with a dihydric or higher alcohol or a mixture such. Ester and d) optionally other monomeric copolymerizable compounds in subordinate Quantities and B. about 10 to 60 percent by weight of at least one water-soluble phenoplast or a corresponding oligomer and C. optionally and advantageously up to about 50 percent by weight of at least one water-soluble aminoplasts or a corresponding oligomer or monomers. References considered: U.S. Patent No. 2,862,901. 609 710/284 11.66 © Bundesdnickerei Berlin