FI61491B - FOERFARANDE FOER FRAMSTAELLNING AV FINKORNIGA PLASTDISPERSIONER SPECIELLT LAEMPADE FOER FAESTANDE GRUNDNING AV MAOLNINGSUNDERLAG - Google Patents

Description

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Federal Republic of Germany-Förbundsrepubliken Tyskland (DE) P 2556327-3 (71) Hoechst Aktiengesellschaft, 6230 Frankfurt / Main 80, Federal Republic of Germany-Förbundsrepubliken Tyskland (DE) (72) Josef Mondt, Königstein / Taunus, Karl Josef Rauterkus

Taunus, Helmut Rinno, Lorsbach / Taunus, Federal Republic of Germany-Förbundsrepubliken Tyskland (DE) (7 * 0 Oy Kolster Ab (5l) Method av malningsunderlag

The invention relates to a process for the preparation of finely divided plastic dispersions which are particularly suitable for fixing primers to paint substrates.

In order to achieve the fixing effect of paint substrates, primers must mainly meet the following requirements:

The binder must penetrate deep into the substrate, adhere well to it after drying and reduce its absorbency. The primer must form a good adhesion base for the brushes. It must be resistant to water, soaping and climatic effects. Solvent-containing primers, which have hitherto been the only ones to meet these requirements, have various disadvantages. The solvent content is physiologically and due to the risk of fire. The tool must be cleaned with solvents. The molecular weight of the binders is limited because the viscosity of the primer at high molecular weight becomes too high or no longer allows high concentrations.

2 61491

Instead, aqueous plastic dispersions offer substantial advantages. They do not contain flammable or physiologically questionable solvents. The tool can be cleaned with water. But above all, in such dispersions, when the molecular weight of the binder is high, high dry matter contents are possible without having to take into account harmfully high viscosities.

In addition, the residual water dries more easily from the coating film than the solvent residues. In addition, plastic dispersions, provided that their emulsifier-protective colloid systems are compatible, can be mixed in a more versatile way than solutions, so that the combinations of properties can be varied widely by mixing different dispersions.

Despite the obvious advantages, aqueous systems have so far not been widely used as primers. Although water-soluble binders penetrate deep into the substrate, they are not sufficiently resistant to water and / or saponification. Although plastic dispersions, with the right choice of monomer and emulsifier-protective colloid system, give water and saponification-resistant coatings, their penetration depth is not sufficient, above all, to adhere to the substrate and insulate it. As has been found by co-polymerization of optically tinting monomers, the dispersions used so far, due to their large average particle diameter, hardly penetrate into the cavities and capillaries of the substrate and mainly form only a film on its surface.

However, German patent DE 1 925 353 discloses a two-step process for obtaining vinyl ester copolymer dispersions with particle sizes of less than 0.2. However, the polymers described therein are not sufficiently resistant to water and saponification and the two-step manufacturing process is complicated.

The present invention relates to a process for the preparation of finely divided plastic dispersions which are particularly suitable for fixing primers to paint substrates, in which the monomers are polymerized in the presence of emulsifiers at a temperature of 10-100 ° C and the pH of the dispersion is adjusted to 7-10. The process is characterized in that the monomer mixture containing I as hardening component 20-80% by weight of styrene and / or methyl methacrylate, II as plasticizer component 20-80% by weight of acrylic acid of straight-chain or 3,61491 branched alcohols having 2 to 8 carbon atoms. ester and / or methacrylic acid ester of straight-chain or branched alcohols containing 4 to 8 carbon atoms, III 0.1 to 5% by weight of q (β-unsaturated carboxylic acid amide, and IV 0.1 to 5% by weight of unsaturated monocarboxylic acid, in the form of a pure monomer mixture or pre-emulsion simultaneously with the initiator in a water bath containing 2 to 8% by weight of anionic emulsifier, based on the monomers, and polymerized to a monomer content of 45% or less by weight of the finished dispersion and an average particulate weight. the size is 0.01 to 0.06 μm.

The method according to the invention provides water- and saponification-resistant, deep-penetrating primers.

The choice of monomers according to rules known to the person skilled in the art must be such that stable dispersions are formed and that the film-forming temperatures of the copolymers are in the preferred range known for the coating technique, i.e. suitably between about -10 and + 25 ° C.

Styrene alone is particularly preferably used as the hardening component. When methyl methacrylate is used, its proportion by weight of the total monomers must not exceed 15% by weight.

Examples of emollient components are ethyl acrylate, propyl acrylate, isopropyl acrylate and acrylic or methacrylic acid esters of butyl alcohol and 2-ethylhexyl alcohol.

Amides of unsaturated carboxylic acids, especially acrylamide or methacrylamide, promote the formation of finely divided dispersions when added during polymerization together with other monomers to the mixture. The process according to the invention preferably uses 1.5-3.5% by weight of acrylamide or methacrylamide, based on the total amount of monomers.

The incorporation of unsaturated monocarboxylic acids into the copolymer increases the stability of the dispersion during manufacture, storage and use. Preferred acids are acrylic acid and methacrylic acid.

On the other hand, it should be noted that Group III and Group IV carboxylic acids as hydrophilic monomers increase the hydrophilicity of the total molecule. In order to prepare with the dispersions according to the invention ·; ·>? *} 'Jf.i; In order not to reduce the water resistance of the primers and coatings applied to 4,61491, the total content of these monomers should be 0.2 to 8.5% by weight. Within this range, it can be higher the higher the content of water-repellent monomers in groups 1-II, i.e. in the upper limit of 0.2-8.5% by weight of said range, when other monomers are particularly water-repellent, such as styrene, butyl acrylate, 2-ethylhexyl acrylate or 2-ethylhexyl methacrylate, and at a lower limit when other monomers are less water repellent, such as methyl methacrylate and ethyl acrylate.

Only styrene is preferably used as the group I hardening monomer. Methyl methacrylate should be used up to 15% by weight, based on the total amount of monomers.

Examples of suitable monomer combinations are (parts by weight): butyl acrylate-styrene-acrylic and / or methacrylic acid-acrylic and / or methacrylamide (40-80 / 60-15 / 0, 1-4 / 0.1-4).

2-ethylhexyl acrylate-styrene-acrylic and / or methacrylic acid acrylic and / or methacrylamide (30-80 / 65-15 / 0.1-4 / 0.1-4).

2-ethylhexyl acrylate-methyl methacrylate-acrylic and / or methacrylic acid-acrylic and / or methacrylamide (30-80 / 65-15 / 0.1-4 / 0.1-4).

Butyl acrylate-methyl methacrylate-acrylic and / or methacrylic acid acrylic and / or methacrylamide 40-80 / 55-15 / 0.1-3 / 0.1-3).

The polymerization must take place in the presence of an anionic emulsifier. As the anionic emulsifiers, for example, alkali salts of sulfuric acid half-esters of alkylphenols or alcohols, sulfuric acid half-esters of further oxyethylated alkylphenols or alcohols or also alkyl or arylsulfonates can be used. Examples of these anionic emulsifiers are the alkali metal salts of the sulfuric acid half-ester of nonylphenol which has reacted with 4-5 moles of ethylene oxide, sodium lauryl sulfate, sodium lauryl ethoxylate sulfate with 8-20 moles of ethylene oxide, sodium sulfate,

The amount of anionic emulsifiers is 2 to 8% by weight, based on the monomers, whereby as the amount of anionic emulsifier increases, the particle size generally decreases.

In addition, in order to increase the stability of the dispersions, nonionic emulsifiers of the type ethoxylated alkylphenols or fatty alcohols, e.g. nonylphenols, can be used with 4-6 moles of ethylene oxide mixed with an anionic emulsifier. When selecting emulsifiers and monomers, care must be taken to form dispersions which do not tend to form agglomerates after preparation or after dilution with water. When using very fine plastic dispersions for impregnation and priming, the formation of larger agglomerates can reduce the infiltration capacity.

Suitable initiators are the customary inorganic per-compounds, such as ammonium persulphate, potassium persulphate, sodium perphosphate and organic peroxides, such as, for example, benzoyl peroxide, organic peresters, such as perisopivalate, in combination with such as with iron, cobalt, cerium and vanadyl salts, preferably alkali or ammonium peroxide sulphates.

The polymerization temperature is +10 to + 110 ° C, preferably +30 to + 90 ° C.

The dry matter content of the dispersions after preparation is 20-45%.

In order to prepare the particularly finely divided dispersions according to the invention, it is preferred to polymerize at a low dry matter concentration. Lowering the dry matter content usually results in finely divided dispersions. As can be seen from Table 1, latices with coarser particles have less penetration and less adhesion than the finely divided dispersions according to the invention. If the finely divided dispersions, due to the wide particle size distribution, contain some coarser particles, then this part does not promote good penetration and no adhesion. Plastic dispersions with a narrow particle size distribution therefore represent a preferred embodiment of the invention.

After finishing the polymerization, the finely divided plastic dispersions are adjusted to pH 7-10, preferably 7.5-9, with alkali, ammonia or amines. It is possible to adjust the dry matter content of low-dry matter dispersions by vacuum distillation without adversely affecting the fineness of the dispersions.

The polymerization can be carried out, for example, by mixing 30-50% of water with 20-50% of the anionic emulsifier and possibly 10-50% of the nonionic emulsifier and monomers with the rest of the water and the remaining emulsifiers; An emulsion is prepared which is added over a period of 1-3 hours to a bath heated to 50-90 ° C.

In this case, the ratio between the monomers and water is chosen so that the resulting dispersion contains 20-45% dry matter.

The amount of anionic emulsifier should be between 2 and 8%, based on the dry matter content selected in each case, based on the monomers.

The reaction mixture is stirred, the initiator is added portionwise in 1-5% aqueous solution in parallel with the addition of the emulsion. At the end of the addition, the whole batch is stirred for a further 1-3 hours at 70-90 ° C. The pH is then adjusted to 7.5-9 with ammonia, aliphatic amines or alkali hydroxides.

Addition of the emulsion by dosing is not a necessary condition for the preparation of finely divided dispersions, since also by dosing the monomer mixture in a bath containing all the water and emulsifiers, finely divided plastic dispersions can be obtained. When plastic dispersions are used for primers and impregnations, the dry matter content of the dispersions has a significant effect on the depth of penetration, the strength of the fixing effect and the reduction of the absorbency of the treated surfaces.

Diluted didperces penetrate deeper into the pores of the substrate than concentrated ones. When concentrated dispersions are used, only a part of the latex particles penetrates the pores, the rest forming a film on the surface. As a result, the use of concentrated dispersions results in a very strong decrease in the absorbency of the substrate as a result of the treatment, and very little use of diluted dispersions.

The fixing effect depends not only on the nature of the polymer but also on the concentration of polymer per unit volume on the treated surfaces. Although very heavily diluted dispersions have a large penetration depth, the plastic content per unit volume is relatively small. In concentrated dispersions, the portion of the polymer that remains on the surface after drying does not promote the adhesion of the deeper layers.

From the above, it is clear that by selecting the dry matter content of the finely divided dispersions, it is possible to adjust the penetration depth, the adhesion and the adhesion to the surface, as well as the suitability of the dispersion for different practical surfaces. The dispersions prepared according to the invention give good results with dry matter contents of 5-25% by weight, preferably 10-20% by weight. Dispersion- • a * ·?

One advantage of pigs is that over a relatively wide concentration range both good penetration depths and good adhesion are possible due to the specific particularly advantageously adjusted plastic content in the treated surface when the average particle size of the latex particles is 0.01-0, 06, ωη. (Particle size determined by light scattering and electron microscopic). As usual with dispersion lubricants, excipients may be added. Of the several known possibilities, only a few are mentioned here as examples:

Solvents to improve film formation and lower film formation temperature, plasticizers, defoamers, preservatives, surfactants for better wetting, and pigments and soluble dyes for dyeing.

The ability to penetrate can be assessed in different ways. Thus, for example, the test substance can be applied to a selected substrate, e.g. by brushing, draining or dripping. After drying, the infiltrated substance is detected from the cross-section. When using dissolved resins, staining with soluble dyes can be used. This method can lead to erroneous results with dispersion-based substances if the aqueous phase also stains. Since in most dispersions the aqueous phase penetrates deeper than the latex particles, the stained zone here does not primarily tell anything about the actual penetration of the latex particles.

In order to show an improved depth effect, the dispersions according to the invention were formed by copolymerizing with vinylsulfonylpyrazoline tinting agents in concentrations of 0.01 to 0.05%, based on the monomers, as optically tinted copolymer dispersions of the over-enriched polymers containing in the latex moiety. Thus, the optical tinting agent cannot be removed from the polymer by extraction. Where the characteristic fluorescence of the optical tinting agent is visible in the substrate under UV light, there is also a polymer.

Optically tinted, finely divided copolymer dispersions were applied to a variety of substrates, e.g. In addition to the method of polymerizing fluorescent substances which make it possible to determine the depth of penetration of the polymer under UV light, other methods are also known. For example, it is suitable to treat the cross-sections of primed or impregnated substrates with a flame of a Bunsen burner, whereby the polymer appears gray-colored. On acid-soluble substrates, it is also possible to brush the cross-sectional surfaces with concentrated sulfuric acid to identify the entrapped polymer. These studies showed that at the same dry matter concentrations, the fine plastic dispersions according to the invention had as good penetration depths and adhesion as known binders in solvent-containing deep primers and that the penetration depth is> 0.06 μm.

The superiority of dispersions with a particle size range <0.06 μm was particularly evident in the fact that even at relatively high dry matter contents, in which a large amount of plastic can already be applied per unit area in one operation - e.g. 15-20% by weight dry matter content - the finest dispersions still penetrate almost completely into the substrate and promote the adhesion and better adhesion of subsequent coats there, while the coarse dispersions do not for the most part penetrate the substrate and only form a film on the surface.

Another method of allowing the finely divided dispersions of the invention to act on a fine-grained bulk material is to examine not only the depth of penetration but also the adhesive effect achieved with a given amount of binder. In this case, it is advantageous that the substance in its penetration area, after drying, leads to the aggregation of the granular substance. Adherent granules can be easily removed and weighed. Weight is a measure of penetration and clamping effect. This test is used to simulate, for example, the adhesion of the surfaces of old, crumbling components.

The experiment was carried out using quat flour W6 (diameter analysis: 50% <40 .mu.m) supplied by Quarzwerke GmbH, 5 Köln-Marienburg, which was collected in flat containers. A hemispherical recess of 2.5 cm in diameter was made in the test substance insertion site by pressing with a punch of similar shape. 2 ml of the dispersion to be examined was added dropwise to this well. After a drying time of 4 hours at room temperature, the described pile was allowed to stand for another 15 hours at 50 ° C in an oven.

The results of these experiments are summarized in Table 1. Suitable iron dispersions prepared according to the invention with a particle size between 0.01 and 0.06 / am and prepared according to Examples 1-6 were examined.

Dispersions with a particle size D greater than 0.08 μm and based on various monomer systems as well as commercially available polymers in organic solvents recommended for deep priming served as reference substances.

It follows from the results that the maximum weight of the adhering granules and thus the best penetrability, together with a good fixing effect, are achieved with the dispersions and polymer solutions according to the invention in organic solvents. (table 1).

The results obtained with aqueous active substance dispersions with larger average particle diameters (D> 0.1 .mu.m) are in all cases clearly inferior to those obtained with the finer divided dispersions according to the invention.

An additional requirement for primers that have a depth effect is that the extension coat applied to the primed substrate has good adhesion and is well adhered to the substrate through the primer. This requirement must also be met when, as a result of the different absorbency of the substrate after repeated application of the primer, the extension lubricants are applied to different thicknesses of the primer. To investigate this point, about 12% of the fine dispersions according to the invention were applied three times, with occasional drying, to the asbestos-cement sheets on the substrate. After triple air drying, this primer layer was coated with a dispersion dye containing a styrene / butyl acrylate dispersion as a binder and pigmented in a ratio of 1: 1.6 (dispersion / pigment filler mixture). A strip of reinforcing fabric made of polyethylene terephthalate was immersed in still fresh dye, and after drying the first brush, the same dye was brushed once more.

When an attempt was made to pull off the tissue strip, good adhesion of the primer to the substrate and good adhesion of the primer $ * c «f> f were observed in the dry state and also after wetting or re-drying with water; ίο 614 91 and between the dispersion paint layer. This terminal for both monomer-controlled soft and hard binder films made from the polymers of Examples 1-6. In all cases, the tissue strip detached, leaving the dispersion dye layer of the weave lattice pattern without raising color from the substrate or primer.

The same results were obtained in cross-sectional drying with a dispersion paint paint in an experiment in which an attempt was made to tear off the dispersion paint film with an adhesive tape glued to the cross-sectional squares. Again, there was no tearing of the brush layer. The invention is illustrated by the following examples.

Example 1

A permanent monomer emulsion is prepared from the following ingredients: styrene 134 parts by weight butyl acrylate 200 parts by weight acrylamide 4.5 parts by weight methacrylic acid 12.0 parts by weight sec sodium salt of alkanesulfonate <C-2-c16 ^ 10-12 parts by weight of nonyl ethenol phenol with a mole of ethylene oxide 5.0 parts by weight of water 400 parts by weight

The emulsion is added to a bath solution containing 230 parts by weight of water, 2 parts by weight of nonionic emulsifier and 8 parts by weight of ionic emulsifier. In parallel with the emulsion dosing, a solution of 2 parts by weight of ammonium persulfate in 40 parts by weight of water is added portionwise.

The dispersion adjusted to pH 8-9 has an average particle diameter of 0.036 μm.

Example 2

Optically tinted, finely divided copolymer dispersions are obtained by additionally dissolving 0.1 part by weight of a vinylsulfonylpyrazoline tinting agent in the monomer mixture according to Example 1 (see German application DE 2 011 552) and then preparing a plastic dispersion.

Both the aqueous plastic dispersion and the dry polymer film give typical blue fluorescence under UV irradiation, which also makes it possible to detect very small amounts of polymer in different substrates. Gel permeation chromatography fractions showed that the optical tinting agent was f.

-Π 61491 uniformly built into the polymer, i.e., no enrichments occur in any of the specified Mole-weight ranges. The optically tinted mixed polymer dispersion has an average particle diameter of 0.038 μm.

Example 3

To a bath of 680 parts by weight of water, 25 parts by weight of secondary sodium alkanesulfonate (C12-C16 to 10 parts by weight of the reaction product of nonylphenol and 8 to 12 moles of ethylene oxide) is added a monomer mixture of: styrene 170 parts by weight of butyl acrylate 170 parts by weight of acrylamide 4 parts by weight of methacrylic acid 10 parts by weight

A solution of 2 parts by weight of araronium persulfate in 40 parts by weight of water is used as initiator.

The average particle diameter is 0.038 / am.

Example 4

A permanent monomer emulsion is prepared from the following substances: styrene 3600 parts by weight of butyl acrylate 3600 parts by weight of acrylamide 100 parts by weight of methacrylic acid 250 parts by weight of sodium lauryl sulfate 340 parts by weight of nonylphenol + 8-12 moles of ethylene oxide 180 parts by weight of ethylene oxide

The emulsion is added to a bath solution containing 5000 parts by weight of water, 80 parts by weight of nonionic emulsifier and 280 parts by weight of anionic emulsifier. At the same time, a solution of 40 parts by weight of ammonium persulfate and 900 parts by weight of water is added in parallel with the monomer emulsion. The dispersion adjusted to pH 8-9 has an average particle diameter of 0.042 .mu.m.

In the reaction vessel, the dispersion can be concentrated to a dry matter content of about 45% in a water jet vacuum. The average particle diameter remains unchanged at 0.042 .mu.m.

Example 5

To a bath of 660 parts by weight of water, 20 parts by weight of water, 20 parts by weight of sodium lauryl ethoxylate sulfate (with 2-5 moles of ethylene oxide) and 8 parts by weight of nonylphenol + 6-10 moles of ethylene oxide are added monomer mixture containing: methyl methacrylate 130 parts by weight butyl acrylate 200 parts by weight acrylic acid 12 parts by weight acrylamide 4 parts by weight

A solution of 3 parts by weight of potassium persulfate in 30 parts by weight of water is used as initiator.

The average particle diameter is 0.041 μm.

Example 6

The ingredients of the bath are as in Example 5.

The monomer mixture contains:

Methyl methacrylate 100 parts by weight butyl acrylate 230 parts by weight acrylic acid 13 parts by weight acrylamide 5 parts by weight

2 parts by weight of potassium persulfate in 20 parts by weight of water are used as initiator. The average particle diameter is 0.045 Jim. Example 7

A stable monomer emulsion is prepared from the following substances: styrene 170 parts by weight of butyl acrylate 170 parts by weight of lauryl sulfate-Na 15 parts by weight of the reaction product of nonylphenol with 8 to 12 moles of ethylene oxide 5 parts by weight of water 450 parts by weight

The emulsion is added to a bath solution containing 200 parts by weight of water, 3 parts by weight of nonionic emulsifier and 8 parts by weight of ionic emulsifier. In parallel with the emulsion dosing, a solution of 3 parts by weight of ammonium persulfate in 30 parts by weight of water is added. The dispersion adjusted to pH 8-9 has an average particle diameter of 0.060.

Comparative Example A

A copolymer dispersion is prepared with 70 parts by weight of vinyl acetate

Versatic-10-acid-vinyl ester 25 parts by weight of crotonic acid 5 parts by weight, with an anionic emulsifier and an inorganic per-compound, the dry matter content of the dispersion being 40-50%. The average particle diameter is 0.620 Jim.

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Comparative Example B

A copolymer dispersion is prepared with 70 parts by weight of vinyl acetate and 30 parts by weight of butyl acrylate according to the instructions of Example A.

The average particle diameter is 0.270 Jim.

Comparative Example C

A copolymer dispersion is prepared with styrene 50 parts by weight of butyl acrylate 50 parts by weight of acrylic acid 2 parts by weight of methacrylic acid 5 parts by weight of acrylamide 3 parts by weight with a mixture of anionic and nonionic emulsifiers and an inorganic compound. The average particle diameter is 0.150 μm. Comparative Example D A copolymer of vinyl acetate 70 parts by weight of maleic acid dibutyl ester 30 parts by weight are dissolved in 60% by weight of ethyl acetate. The viscosity at 20 ° C is 80 p according to HiSppler (DIN 53015).

From this solution, a primer having a depth effect is prepared as follows: 60% by weight of a copolymer solution in ethyl acetate 28 parts by weight p

Shellsol A 1 62 parts by weight of ethyl glycol acetate 10 parts by weight

Comparative Example E A copolymer of vinyltoluene with 85 parts by weight of acrylic acid 2-ethylhexyl ester and 15 parts by weight and having a viscosity of 60 cP in a 30% solution in xylene at 20 ° C according to Höppler is prepared as follows: copolymer 170 parts by weight of test gasoline v 545 parts by weight p

Shellsol A 285 parts by weight.

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Table 1;

Penetration tests on quartz sand piles

Preiraerk- Average particle- Glued diameter of the adhering granules Qum) weight of the light barrier (g) after addition of 2 ml of 17% and 11% dispersion 1 0.036 12.3 13.6 2 0.038 11.8 12.5 3 0.038 12.1 12.8 4 0.042 10.5 11.9 5 0.041 11.3 11.9 6 0.045 11.1 11.5 7 0.060 10.5 11.0

Comparative Examples A 0.620 0.6 1.1 B 0.270 3.4 3.8 C 0.150 6.0 6.4 D --- 10.8 11.0 E --- 10.4 11.2 fH ';

Claims (1)

Process for the preparation of finely divided plastic dispersions, which are particularly suitable for fixing primers, in which monomers are polymerized in the presence of emulsifiers at a temperature of 10 to 100 ° C and the pH of the dispersion is adjusted to 7 to 10, characterized in that the monomer mixture contains 80% by weight of styrene and / or methyl methacrylate, as an emollient II 20-80% by weight of acrylic acid ester of straight-chain or branched alcohols having 2 to 8 carbon atoms and / or methacrylic acid ester of straight-chain or branched alcohols having 4 to 8 carbon atoms, 1-5% by weight of β-unsaturated carboxylic acid amide, and IV 0.1-5% by weight of <= (, β-unsaturated monocarboxylic acid, are added in the form of a pure monomer mixture or pre-emulsion simultaneously with the initiator to a water bath containing 2-8 % by weight of anionic emulsifier, based on the monomers, and pol is dimerized, the amount of monomer used being such that the finished dispersion has a solids content of up to 45% by weight and an average particle size of 0.01 to 0.06. HPi .f. ../.