DE3826250A1 - Polymer particle dispersion and coating process - Google Patents

Abstract

Described is a polymer particle dispersion produced by dispersion polymerisation of at least one ethylenically unsaturated monomer in the presence of a dispersion stabiliser in an organic solvent in which ethylenically unsaturated monomers are soluble but the produced polymer particles are insoluble. The dispersion stabiliser is selected from: (i) a siloxy-containing copolymer produced by copolymerisation of about 5 to about 60% by weight of a polymerisable unsaturated monomer A, which contains in its molecule at least one polymerisable unsaturated group and at least one carbon-bonded siloxy group of the following formula <IMAGE> in which R<1> and R<2> are each C1-18-alkyl, phenyl, allyl, Cl, H or F and R3 is C1-18-alkyl, phenyl or allyl and about 40 to about 95% by weight of a polymerisable unsaturated monomer B which is copolymerisable with the monomer A, the siloxy-containing copolymer having a number average molecular weight from about 1000 to about 35,000; and/or (ii) a modified copolymer having one or more free-radically polymerisable unsaturated double bonds introduced into the siloxy-containing copolymer. Also described is a coating process involving two coating steps and a baking step using this polymer particle dispersion ... Original abstract incomplete.

Description

The present invention relates to a dispersion of Polymer particles and a coating process with two Coating steps and a baking step using this dispersion.

In recent years, plastics are increasing in the automotive industry for the production of Body panels of motor vehicles, Motor vehicle parts and the like. Has been used to z. B. the Reduce weight of the vehicles. This tendency has too a need for the development of Coating compositions performed because of the low heat resistance of plastics at lower Temperatures can be cured. To save labor, to simplify the assembly process and the like., has been introduced universal coating system in which Automotive body panels made of steel and Motor vehicle parts made of plastics, such. B. fenders, Bumpers and the like, be pre-assembled and simultaneously with coated the same coating composition. Consequently, there is currently an urgent need for the Development of coating compositions, which at lower temperatures are crosslinkable and in terms of the properties and appearance of the coating film the common coating compositions for Motor vehicle body panels comparable or are superior. There is also a great need for the Development of a new coating process that it allowed, especially in the coating process with two Coating stages and a baking stage, which in the in recent years to a large extent for the coating of Automotive parts and the like. Have been used, the Coating compositions at lower temperatures too network.  

Investigations have been made at lower levels Temperature crosslinkable coating compositions, e.g. B. a combination of polyol-type resin and polyisocyanate, a combination of multifunctional epoxy resin and a Compound or a prepolymer, each having an acid group or an acid anhydride group, and others Combinations, some of which were also used. These However, coating compositions have the serious drawback that they all take the form of two Packs and have a pot life of only a few hours or have less. The above mentioned Coating compositions may take the form of a Single pack can be made by one with one suitable blocking agent blocked polyisocyanate instead a non-blocked polyisocyanate used. The desired, low-temperature curable However, coating composition could not do so be prepared because the blocking agent used a has high dissociation temperature.

An object of the present invention is to provide a Dispersion of polymer particles, which has a high storage stability even when added with the addition of a curing agent in a single-package type curable composition is brought, which is curable at low temperature and which can form a coating film which is in its Properties, such. As hardness, weather resistance and the like. and appearance is excellent.

Another object of the present invention is to provide a coating process with two coating stages and a baking stage in which the Coating composition curable at low temperature is and can form a coating film, the  in terms of its properties and appearance is excellent.

Other features of the invention will become apparent from the following Description obviously.

The present invention provides a dispersion of Polymer particles prepared by dispersion polymerization at least one ethylenically unsaturated monomer in Presence of a dispersion stabilizer in one organic solvent in which the ethylenic unsaturated monomers is soluble, but by Dispersion polymerization of the monomer produced Polymer particles are insoluble, which characterized in that the dispersion stabilizer is selected from:

• (i) a siloxy-containing copolymer prepared by copolymerizing from about 5 to about 60% by weight of a polymerizable unsaturated monomer A having in its molecule at least one polymerizable unsaturated group and at least one carbon atom-bonded siloxy group represented by the following formula in which R₁ and R₂ are each C _1-18 alkyl, phenyl, allyl, Cl, H or F and R₃ is C _1-18 alkyl, phenyl or allyl, and about 40 to about 95% by weight of a polymerizable unsaturated monomer B which is copolymerizable with the monomer A, wherein the siloxy-containing copolymer has a number average molecular weight of about 1,000 to about 35,000; and or
• (ii) a modified copolymer containing one or more introduced into the siloxy-containing copolymer radically polymerizable unsaturated double bonds having.

The present invention also provides Coating process with two coating stages and one Baking step, which includes the application of a Pigment-containing coating composition on a Substrate to form a first layer, the subsequent Applying a clear coating composition to the first layer to form a second layer and the Hardening of the two uncured layers by simultaneous Heating, the method being characterized in that the coating composition for the first layer and / or the clear coating composition for the second Layer contains:

• (i) the inventive dispersion of polymer particles and
• (ii) a curing agent reactive with hydroxy groups.

The inventive dispersion of polymer particles can are prepared by dispersion polymerization of at least one unsaturated monomer in an organic Solvent in the presence of one or more copolymers as a dispersion stabilizer, prepared by Copolymerization using a polymerizable unsaturated monomers having at least one in its molecule polymerizable unsaturated group and at least one Having siloxy group as one of the monomer components. The continuous phase of the formed from the dispersion Coating film consists mainly of the Dispersion stabilizer, while the disperse phase thereof comprising the polymer particles. The siloxy group used in the Dispersion stabilizer is present in water Presence of a catalyst as below Reaction scheme shown hydrolyzed:

The hydrolysis of the siloxy group is due to the Moisture in the air before or after application of the Coating composition resulting in a hydroxyl group leads, which reacts with a curing agent to the Crosslinking reaction to accomplish. Accordingly, not allowed once a single packaging composition, which the Contains dispersion of the polymer particles and a curing agent, the immediate reaction between the dispersion stabilizer and the curing agent so that the composition excellent in storage stability. Farther prevents the addition of a water-trapping agent for Dispersion the hydrolysis of the siloxy group in the Dispersion stabilizer by water, creating a Long-term storage stability is ensured. A Single-package coating composition with one improved low-temperature crosslinkability will also created by incorporating one at low temperature crosslinkable polyisocyanate or the like. As a curing agent in the dispersion.

When a coating composition containing the Contains polymer particle dispersion and a curing agent, as a base coat in a coating process with two Coating stages and a baking stage is used not only does the composition show the storage stability in a single package that allows easy handling, but it also has the following properties. The Viscosity and thixotropic behavior of Coating composition decreases due to the presence  of dispersed polymer particles, with the result that the pigment (especially the metallic flake pigment) a Orientation and fixation learns, which leads to a Marbling in the metallic texture prevents what in turn causes a coating film with excellent appearance is formed.

When a clear coating composition containing the Contains polymer particle dispersion and a curing agent, used for a second layer, the serve dispersed polymer particles, the strength of the To improve coating film and the on the Coating film applied load to alleviate, resulting in a Improvement of impact resistance and crack resistance Weather influences leads. In this case, the Increase in viscosity and thixotropic behavior of the Coating composition by the presence of Polymer particles trailing the on a vertical Substrate surface applied coating composition and makes the coating composition to form a thicker coating applicable.

When the coating composition for the base coat and the clear coating composition for the clear Coat both the polymer particle dispersion and a Polyisocyanate as a curing agent, the two Coatings simultaneously under Low temperature bake conditions of about 70 to cured at about 80 ° C for about 20 to about 30 minutes become, thus leading to a coating film with two Layers, which in terms of its properties, such. B. Hardness, adhesion, weather resistance and the like, but also is excellent in appearance.

The polymerizable unsaturated monomer A containing a Component of the siloxy-containing copolymer is that as  Dispersion stabilizer in the preparation of Polymer particle dispersion is used, monomers which were prepared by reacting a hydroxy-containing vinyl monomers described below with trialkylchlorosilane, triphenylchlorosilane, Triallylchlorosilane, dialkylchlorosilane, dialkyldichlorosilane, Dialkylhydrosilane or the like. In the presence of a Hydrogen chloride scavenger, such as. B. triethylamine or Pyridine. The term "alkyl" is intended to include C₁-C₆ alkyl groups, among which methyl, ethyl, propyl, butyl and phenyl are preferred. Typical examples of this polymerizable unsaturated monomers A are

Trimethylsiloxyethyl acrylate or methacrylate,
Trimethylsiloxypropyl acrylate or methacrylate,
Trimethylsiloxybutyl acrylate or methacrylate,
Triethylsiloxyethyl acrylate or methacrylate,
Tributylsiloxypropyl acrylate or methacrylate,
Triphenylsiloxyethyl acrylate or methacrylate, and the like.

These monomers may be used singly or as a combination of at least two monomers are used.

Representative examples of the hydroxy-containing vinyl monomer are hydroxyalkyl acrylates or methacrylates, such as. B. β -Hydroxypropylacrylat or methacrylate, β -Hydroxypropylacrylat or methacrylate, β -Hydroxybutylacrylat acrylate or methacrylate, and the like, N-methylolated acrylamide or methacrylamide. Addition products of β- hydroxyethyl acrylate or methacrylate and ε- caprolactone (e.g., Placcel FM, FA series, product of Daicel Chemical Industries, Ltd., Japan or TONE®-100, product of Union Carbide Corporation, USA); Polypropylene glycol monomethacrylate (e.g., Blenmer PP-1000, product of Nippon Oil & Fats Co., Ltd., Japan), polyethylene glycol monomethacrylate (e.g., Blenmer PE series, product of Nippon Oil & Fats Co., Ltd., Japan); An addition product of unsaturated carboxylic acid and monoepoxy compound, examples of the unsaturated carboxylic acid being acrylic acid or methacrylic acid, maleic acid, fumaric acid, itaconic acid and the like, and exemplified as the monoepoxy compound "Cardura E" (product of Shell Chemical Co., Ltd., USA , Glycidyl ester of a branched fatty acid), glycidyl ester of octylic acid, glycidyl ester of coconut fatty acid and similar monoglycidyl esters of monobasic carboxylic acids, butyl glycidyl ether and like monoglycidyl ethers and the like.

Typical examples of the polymerizable unsaturated monomer B which is copolymerized with the polymerizable unsaturated monomer A to produce a siloxy-containing copolymer are C₁-C₂₂-alkyl esters of acrylic acid or methacrylic acid; styrene; vinyltoluene; t-butylstyrene; α- methylstyrene; Glycidyl acrylate or methacrylate; 2-ethoxyethyl acrylate or methacrylate; Acrylonitrile or methacrylonitrile; Cyclohexyl acrylate or methacrylate; unsaturated carboxylic acids, such as. As acrylic acid or methacrylic acid, maleic acid, fumaric acid, itaconic acid and the like., Diesters of maleic acid or fumaric acid with monohydric C₁-C₁₈ alcohols; Acrylamides or methacrylamides, such as. Acrylamide or methacrylamide, N-alkoxymethylated acrylamide or methacrylamide; N, N-di-C₁-C₄-alkylamino-C₁-C₄-alkyl acrylates or methacrylates, such as. N, N-dimethylaminoethyl acrylate or methacrylate; Phosphoric acid group-containing acrylate or methacrylate; vinyl acetate; Hexafluoropropylene, tetrafluoroethylene and like fluorine-containing vinyl monomers; and the like. For use, at least one of these monomers selected according to the intended coating properties is blended with the polymerizable unsaturated monomer A.

The polymerizable unsaturated monomers A and B become used in the following proportions. The amount of  unsaturated monomer A is about 5 to about 60 wt%, preferably about 5 to about 40% by weight, while the amount of the unsaturated monomer B is the remainder and, suitably about 40 to about 95% by weight, preferably about 60 to about 95% by weight is. If less than 5 wt .-% of the unsaturated Monomers A, this leads to a unsatisfactory result. When more than 60% by weight of the unsaturated monomers A is used is the Dispersion stabilizer by hydrolysis an excessively high Hydroxyl number conferred, resulting in disadvantages such. B. deteriorated moisture resistance of the Coating film leads.

The siloxy-containing copolymer, as such or after Modification can be used as a dispersion stabilizer can be prepared from the polymerizable unsaturated monomers A and B by conventional Methods that are commonly used, for. B. by a solution polymerization using a radical polymerization initiator.

Suitable free-radical polymerization initiators are those commonly used for the polymerization of acrylic monomers are used. Representative for are useful radical polymerization initiators Azobisisobutyronitrile, di-tert-butyl peroxide and Benzoyl peroxide. Exemplary of suitable solvents Toluene, xylene and like aromatic hydrocarbons; Ethyl acetate, butyl acetate, cellosolve acetate and the like Acetate-type solvents; methyl ethyl ketone, Methyl isobutyl ketone and similar ketone-type solvents; Butanol, isobutanol and similar solvents from Alcohol type; ethylene glycol monomethyl ether, Ethylene glycol monoethyl ether and similar solvents from Ether alcohol type; and the like. When the polymer particle dispersion  of the present invention in admixture with a polyisocyanate with free isocyanate groups as a curing agent or with a active unsaturated isocyanate is used, which is the Give dispersion stabilizer a graft-active site should, the solvents of the alcohol type under the above Examples can not be used as solvents because of a such solvent react with the isocyanate groups would.

If necessary, it is possible to use a chain transfer agent that is commonly used, such as. B. Merceptane, α- methylstyrene, "Dipentene T" (product of Nippon Terpene Chemical Co., Ltd.), etc., use.

The siloxy-containing copolymer thus obtained has a number average molecular weight (n) of preferably about 1,000 to about 35,000, more preferably about 3,000 to about 15,000. If the n of the copolymer is smaller than 1,000, the three-dimensional repulsion between the particles in the polymer particle dispersion is so insufficient that the polymer particles tend to agglomerate and precipitate. If the n of the copolymer is higher than 35,000, it is difficult to dissolve it in the organic solvent serving as a dispersion solvent, and the dispersion of the polymer particles may then have a significantly increased viscosity.

Although the siloxy-containing copolymer as such Dispersion stabilizer is usable, it is advantageous to use a modified copolymer in which one or several radically polymerizable unsaturated Double bonds have been introduced, being average about 0.1 to about 1.5, preferably about 0.3 to about 1.0 double bonds per molecule are present. The The reason for this is that introduced into the copolymer radically polymerizable, unsaturated double bond as  Grafting site for the polymer particles during the Dispersion polymerization acts and the storage stability and the mechanical stability of the thus obtained May increase polymer particle dispersion. The introduction of more than an average of 1.5 double bonds in the Copolymer molecule leads to an increased proportion Copolymer molecules with a multiplicity of double bonds in the Molecule and can lead to an increase in viscosity and during the dispersion polymerization, a gelation cause.

The radically polymerizable unsaturated group (s) Double bond (s) can be produced by various methods in the Siloxy-containing copolymers are introduced, for. B. by Performing an addition reaction between a Epoxy-containing, unsaturated monomers, such as. B. Glycidyl acrylate or methacrylate, and the carboxyl group of a copolymer prepared using Acrylic acid, methacrylic acid or the like as part of the polymerizable unsaturated monomers B in the presence a catalyst, such as. B. dimethylaminoethanol or similar tertiary amines, by carrying out a Addition reaction between the carboxyl-containing unsaturated monomers and the epoxy group in the Copolymers, or by effecting an addition reaction between an isocyanatoethyl acrylate or the like Isocyanate-containing unsaturated monomers and the Hydroxy group of a copolymer prepared under Use of a small amount of hydroxy-containing unsaturated monomer.

Other suitable combinations are for. B. a combination of Acid anhydride and hydroxy group, a combination of Acid anhydride and mercapto group. The conditions for the Addition reaction between the reactive groups well known and it goes without saying that the  Reaction temperature of the type of combination of reactive Depends on groups and with the use of a catalyst varied.

Optionally, in a siloxy-containing copolymer an allyl group can be introduced by using a Allyl methacrylate or the like as part of the monomer together with an azo-type catalyst in the preparation of a Copolymers, followed by the use of benzoyl peroxide or similar peroxide type catalysts in the Dispersion polymerization, so that the allyl group as Graft-active site can be used.

In the preparation of the dispersion stabilizer according to the Care should be taken in the present invention that the following conditions are met. Because the polymer particles in the organic solvent used for the dispersion of Polymer particles is used, must be insoluble In general, a solvent mixture used, the predominantly a low polarity solvent, such as z. B. an aliphatic hydrocarbon type solvent, contains. The dispersion stabilizer must be in the Solvent mixture are dissolved and is therefore desirably a polymer having a similar Polarity (eg a similar solubility parameter) as the solvent used, namely with a low Polarity.

While the presence of a hydroxy group, carboxy group or the like. In a dispersion stabilizer, the polarity of the Increased dispersion stabilizer, the polarity of the Dispersion stabilizer of the present invention advantageously be reduced to a noticeable degree, because of this dispersion stabilizer instead of the hydroxy groups Contains siloxy groups by hydrolysis in hydroxy groups can be converted.  

For the humiliation of the polarity of the Dispersion stabilizer, however, it is desirable as a part of the polymerizable unsaturated monomer B Alkyl acrylate or methacrylate having an alkyl group with 4 or more carbon atoms in an amount of about 10% by weight or above, preferably about 30 wt .-% or above, based on the total monomer B to use.

The as dispersion stabilizer in the present invention copolymers to be used may be used singly or as a mixture of at least two of them, concerning theirs Composition and / or molecular weight different are to be used. Next you can if necessary along with a small amount of another type of Dispersion stabilizer, such as. Alkyd resin, acrylic resin, Graft polymer of poly-12-hydroxystearic acid and acrylic resin, Cellulose derivative or the like. These others Dispersion stabilizer types can be used in an amount of about 50% by weight or less, based on the total amount on dispersion stabilizers.

According to the present invention, at least one ethylenically unsaturated monomer Dispersion polymerization in the presence of Siloxy-containing copolymers as dispersion stabilizer in the organic solvent.

The useful for the polymerization organic Solvents are z. B. those by the polymerization produced polymer particles practically do not dissolve the but the dispersion stabilizer and the ethylenic dissolve unsaturated monomers well.

Examples of such organic solvents are aliphatic hydrocarbons, such as. Hexane, heptane, octane and the like; aromatic hydrocarbons, such as. Benzene,  Toluene, xylene and the like; Solvents from alcohol, ether, Ester or ketone type, such as. For example isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, octyl alcohol, Ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, Diethyl glycol monobutyl ether, methyl isobutyl ketone, Diisobutyl ketone, ethyl amyl ketone, methyl hexyl ketone, Ethyl butyl ketone, ethyl acetate, isobutyl acetate, amyl acetate, 2-ethylhexyl acetate, and the like. These organic solvents may be alone or as a mixture of at least two of them be used. Preferred examples thereof are one Solvent mixture with a predominant proportion of aliphatic hydrocarbon and a suitable amount of aromatic hydrocarbon and / or a Acohol, ether, ester or ketone type solvents. The organic usable for the present invention Solvent may be trichlorotrifluoroethane, Metaxylene hexafluoride, tetrachlorohexafluorobutane or the like Solvent included.

When an isocyanate-containing compound, such as. B. Polyisocyanate, asl curing agent for the Polymer particle dispersion is used, the should Use of a hydroxy-containing organic Solvent, such as. B. a solvent from the alcohol or ether alcohol type.

In the presence of the dispersion stabilizer in the organic Solvent to be polymerized ethylenically unsaturated Monomers are not particularly limited and include diverse monomers, as long as they are radical polymerizable unsaturated monomers. typical Examples of suitable monomers are the following:

• (a) C₁-C₁₈ alkyl acrylate or methacrylate, such as. B. Methyl acrylate, ethyl acrylate, propyl acrylate,  Isopropyl acrylate, butyl acrylate, hexyl acrylate, Octyl acrylate, lauryl acrylate, methyl methacrylate, Ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, Butyl methacrylate, hexyl methacrylate, octyl methacrylate, Lauryl methacrylate and the like; Glycidyl acrylate or methacrylate; C₂-C₈ alkenyl acrylate or methacrylate, such as z. Allyl acrylate or methacrylate and the like; C₂-C₈ hydroxyalkyl acrylate or methacrylate, such as. B. 2-hydroxyethyl acrylate or methacrylate, 2-hydroxypropyl acrylate or methacrylate and the like; and C₃-C₁₈ alkenyloxyalkyl acrylate or methacrylate [t, such as. B. Allyloxyethyl acrylate or methacrylate and the like;
• (B) vinyl aromatic compounds, such. Styrene, α -methylstyrene, vinyltoluene, p-chlorostyrene, vinylpyridine and the like;
• (c) α, β- ethylenically unsaturated acids, such as. Acrylic acid, methacrylic acid, itaconic acid and the like;
• (d) multifunctional unsaturated monomers suitable for a Crosslinking between the particles are useful, such as. B. Divinylbenzene, ethylene glycol diacrylate or dimethacrylate;
• (e) siloxy-containing unsaturated monomers, such as. B. the polymerizable unsaturated monomers A, which is suitable for the Preparation of the dispersion stabilizer is useful;
• (f) other monomers, including acrylonitrile, Methacrylonitrile, methyl isopropenyl ketone, vinyl acetate, Veoba Monomer (trademark, product of Shell Chemical Co., Ltd., USA), vinyl propionate, vinyl pivalate and the like.

Among these monomers, such monomers or a Monomer mixture which is at least about 40% by weight  Acrylate or methacrylate and in particular a Monomer or a monomer mixture, at least about 30 wt .-% acrylate or methacrylate with C₁-C₄-alkyl groups, under the condition that the Total content of acrylate or methacrylate at least 40% by weight is.

The polymerization of such monomers is carried out using a radical polymerization initiator. Suitable radical polymerization initiators are, for. B. Initiators of the azo type, such. B. 2,2'-azobisisobutyronitrile, 2,2'-azobis (2,4-dimethylvaleronitrile) and the like, and initiators of the peroxide type, such as. B. benzoyl peroxide, lauryl peroxide, tert-butyl peroctoate and the like. The polymerization initiator becomes in an amount of about 0.2 to about 10 parts by weight, preferably about 0.5 to about 5 parts by weight, per 100 parts by weight of the monomer to be polymerized.

An appropriate amount of the dispersion stabilizer, however can vary widely, depending on its nature, is about 5 to about 70 wt.%, preferably about From 10 to about 60% by weight based on the combined amount of the monomer to be polymerized Dispersion stabilizer.

The total concentration of the monomer and the Dispersion stabilizer in the organic solvent is in the range of about 30 to about 70% by weight, preferably about 30 to about 60% by weight.

The polymerization can be carried out by conventional Method. The temperature for the polymerization reaction is about 60 to about 160 ° C. The reaction can usually ended in about 1 to about 15 hours become.  

The polymer particles of the dispersion can be crosslinked in a or non-crosslinked form in the dispersion.

When the polymer particles in a crosslinked form in the Dispersion, a curing agent, such as. B. Polyisocyanate, used in an amount sufficient to only the dispersion stabilizer as the continuous phase to network. Consequently, it is advantageous in terms of cost to use the polymer particles in cross-linked form when a expensive curing agent, such as. As polyisocyanate or the like., is used.

The polymer particles can z. B. in a crosslinked form be obtained by using a small amount of Divinylbenzene or similar multifunctional unsaturated Monomers as the ethylenically unsaturated monomer in the Dispersion polymerization or by carrying out the Dispersion polymerization in the presence of a catalyst, such as B. a tertiary amine, using small Amounts of glycidyl methacrylate or the like Epoxy-containing unsaturated monomers and acrylic acid or similar carboxy-containing unsaturated monomers as Monomers for dispersion polymerization.

The polymer particle dispersion according to the invention is characterized by excellent dispersion stability and finds Use not only as a coating composition, but Also as a shaped body, adhesive, filler and the like. The Dispersion according to the invention, although they are as such can be used, taking into account the Coating film properties suitably in mixture used with a curing agent.

The most preferred curing agent is because of its Low temperature crosslinkability and its  Coating Film Properties Polyisocyanate. However, you can for applications that are not networkable at low Temperatures also require aminoplasts to be used.

Examples of suitable polyisocyanates are aromatic Diisocyanates, such as. Tolylene diisocyanate, Diphenylmethane diisocyanate, xylylene diisocyanate and the like; aliphatic diisocyanates, such as. Tetramethylene diisocyanate, Hexamethylene diisocyanate, trimethylhexane diisocyanate and the like; alicyclic diisocyanates, such as. B. isophorone diisocyanate, Methylcyclohexane-2,4- (or 2,6-) diisocyanate, 4,4'-methylenebis (cyclohexyl isocyanate), 1,3-di (methyl isocyanate) cyclohexane and the like; adducts of such diisocyanates and polyhydric alcohols as z. As ethylene glycol, propylene glycol, neopentyl glycol or Trimethylolpropane, polyester resins with extremely low Molecular weight and having two or more functional groups, which are reactive with isocyanate groups (including the Oil-modified types), or with water; biuret these isocyanates, polymers of these diisocyanates (including the oligomers); and the like. With regard to Coating properties is a preferred ratio of Polyisocyanate to the polymer particle dispersion such that OH / NCO (equivalent ratio) is from 1 / 0.2 to 1/3 (where OH the entire OH, including the hydroxyl groups, the caused by the hydrolysis of the siloxy groups is).

Although in this case also the polyisocyanate-containing Dispersion in the form of individual packaging is suitable to the To achieve objects of the present invention is natural also the dispersion in the form of two packs containing the Requires mixing the components before use, usable.

When the polyisocyanate-containing dispersion in the form of a Single packaging is provided, it is in  With regard to the storage stability desirable that in the organic solvent and in the resin solid Hydroxyl groups at low temperature with Polyisocyanate react, are absent.

As aminoplasts, usable are those hitherto known are, such. B. butylated melamine, methylated melamine, Melamine with partially butyl-esterified and ethyl-esterified Parts, urea-formaldehyde resin and the like.

A preferred amount of aminoplast in about 10 to about 40 wt .-%, based on the resin solids of Polymer particle dispersion of the present invention. On Curing catalyst for aminoplasts, such as. B. p-toluenesulfonic acid or similar acid catalysts be added to increase the crosslinkability. A preferred amount of curing catalyst used about 0.1 to about 10 wt .-%, based on the Resin solids.

In the polymer particle dispersion of the present invention, the siloxy group of the copolymer reacts with the moisture in the air and is hydrolyzed to form a hydroxy group reactive with a curing agent. It is preferred to use a catalyst which can accelerate the hydrolysis. Suitable examples of such catalysts are acidic catalysts, such as. Phosphoric acid, phosphoric acid esters, phosphorous acid esters, phosphoric acid esters containing unsaturated groups, p-toluenesulfonic acid and amine salts thereof, benzoic acid, trichloroacetic acid, trifluoroacetic acid, naphthalenedisulfonic acid and amine salts thereof and the like; Amines, such as Ethylenediamine, N- β- aminoethyl- γ -aminopropyltrimethoxysilane, butylamine, dibutylamine, t-butylamine, hexylamine, triethylamine and the like; alkyl titanate; Metal salts of carboxylic acids, such as. Dioctyltin diacetate, dibutyltin diacetate, dibutyltin dilaurate, zinc octylate and the like, monobutyltin sulfide and like sulfide type organotin compounds and dioctyltin mercaptide and the like mercaptide type organotin compounds; Compounds that can generate fluoride ions, such as. Tetraethylammonium fluoride, cesium fluoride and the like; etc. The amount of curing catalyst used is about 0.001 to about 10 weight percent, preferably about 0.005 to about 8 weight percent, based on the resin solids.

When the polymer particle dispersion according to the invention as Single packing type is produced, together with one Hardeners, such as. As polyisocyanate or the like., It is desirable to convert the siloxy groups into To prevent hydroxy groups to have long-term stability sure. To prevent the conversion must have a small amount of water that enters through a water-trapping Funds are intercepted. In other words, the addition of one Water-trapping agent that reacts with water is advantageous to ensure long-term stability. The Water-trapping agent may be used in the production of Siloxy-containing copolymers are added. Examples for suitable water-intercepting agents that are mixed with water are trialkyl, such as. B. Trimethyl orthoformate, triethyl orthoformate, tributyl orthoformate and the like; Trialkylorthoacetate, such as. B. trimethyl orthoacetate, Triethyl orthoacetate, tributyl orthoacetate and the like; Trialkylorthoborates, such as. Tributyl orthoborate, Triethyl orthoborate and the like; Silica esters, such as. B. Tetramethylsilicate, tetraethylsilicate, tetrabutylsilicate, Tetra (2-methoxyethyl) silicate, tetra (2-chloroethyl) silicate, Tetraphenylsilicate, tetrabenzylsilicate and the like; hydrolyzable ester compounds, such as. B. condensates of Silicic acid esters, including a dimer, trimers, Tetramers or hexamers of tetraethylsilicate, e.g. B. "Ethyl Silicate 40" (product of Colcoat Co., Ltd., Japan, a mixture of tetrameric, pentameric and hexameric  Tetraethyl silicate) and the like; and connections with Isocyanate groups, such as. For example, phenyl isocyanate, p-chlorophenyl isocyanate, benzenesulfonyl isocyanate, p-toluenesulfonyl isocyanate, isocyanate methacrylate and the like.

The amount of water scavenging agent used is at about 0.1 to about 0.30 weight percent, preferably about 0.5 to about 20% by weight, based on the Resin solids.

For use as a coating composition or the like the polymer particle dispersion of the invention further various common additives, in addition to the above described, if necessary. Examples of other additives are pigments, plasticizers, Decomposition inhibitors, leveling agents, Ultraviolet absorber, pigment dispersant and the like.

The dispersion may also contain other compatible resins.

While the polymer particle dispersion according to the invention in Different methods can be used, it can be yours Features best when used as Single-package type coating composition is used, which is a polyisocyanate as a curing agent contains.

The coating compositions thus provided of the single packaging type can by usual Coating method, such. Brushing, spraying, Roller coating or the like., Are applied. These Coating composition is in terms of their Storage stability outstanding and is in a broad Temperature range of about 50 to about 180 ° C curable. In particular, the coating composition may be below Low temperature bake conditions of about 70 to  cured at about 80 ° C for 20 to about 30 minutes, and thereby gives a coating which, in terms of their Hardness, adhesion, weather resistance and other properties remarkable and in terms of the appearance of the Coating film is excellent.

The polymer particle dispersion and curing agent containing coating composition can in Coating process with two coating stages and one Burn-in stage used to be a primer first Layer and / or a clear coating as a second layer to build.

When used as the first layer for the stem, contains the coating composition in particular Pigment, as well as the polymer particle dispersion and a Curing agent and may, if necessary, continue the above include additives, including one the Hydrolysis accelerating catalyst, one Water scavenging agent, a curing catalyst, a Leveling agent, a thickener, one compatible resin, a plasticizer and the like. Examples suitable pigments are those commonly used be used, such as. B. organic coloring pigments, inorganic coloring pigments, aluminum powder, mica powder with high brilliance, stretch pigment and the like.

Examples of suitable compatible resins are acrylic resins, Solution type siloxy-containing acrylic resins, polyester resins and the like. If the single-pack provided Coating composition a polyisocyanate as Contains hardening agent is the use of Hydroxy-containing resin in terms of storage stability undesirable, whereas the use of siloxy-containing Solution-type acrylic resin is desired because of this during the baking process reacts with the curing agent and a  has good storage stability.

When the coating composition containing the Contains polymer particle dispersion and the curing agent, is used for the bottom line, the continuous Phase of the primer made mainly from Curing agent and the siloxy-containing copolymer as Dispersion stabilizer and the polymer particles are evenly dispersed therein. The presence of the Polymer particles increase viscosity and thixotropic Behavior of the coating composition, so that the pigment (especially the metallic flake pigment) its Orientation and fixation is experienced, even if the polarity the matrix is lowered by the presence of siloxy groups becomes. As a result, the coating composition shows not only the properties of the polymer particle dispersion, d. H. a remarkable storage stability in the Single-pack shape, lower hardenability Temperature and excellent coating properties, such as z. Hardness, but also the property that they are in Coating process with two coating stages and one Burning step, especially in metallic Coating process, forming a coating film, the is free of disadvantages, such. B. the marbling in the metallic texture, the migration of the composition, the Tracking, etc.

When the coating composition, in particular the Polymer particle dispersion of the invention Hardener and a pigment containing, to form a It is possible to use the second line as the second line Layer a clear coating composition, the in particular the polymer particle dispersion according to the invention and a curing agent, or a clear one Coating composition already applied to the application Plastics or metal substrates is known to use  which can form the coatings, in terms of appearance the coating film (clear gloss, surface smoothness, Gloss and the like), the weather resistance (retention of the Gloss, no matting, resistance to limestone (chalking) and the like), the chemical resistance, the Water resistance, moisture resistance, the Hardenability, etc. is excellent. Among such known Coating compositions are those known as Carrier Component Aminoacrylic Resins, Aminoalkyd Resins, Aminopolyester resins, acrylic polyol polyisocyanate resins of Two-pack type and the like., Included. The shape of this Coating compositions is not particularly limited and it can not be any of the organic solution type aqueous dispersion type, aqueous solution (dispersion) type, Powder type or high solids type and the like his.

When the clear coating composition, in particular the polymer particle dispersion of the invention and a Contains hardening agent, for a second layer in Coating process with two coating stages and one Burning stage is used, they can continue, if required, contain other additives, such as. B. a the Hydrolysis accelerating catalyst, a water-trapping Agent, a curing catalyst, a leveling agent, a Thickeners, ultraviolet absorbers, light stabilizers, a compatible resin, plasticizer and the like. A pigment can incorporated into the coating compositions Be clear as this the transparency of the colored Coating composition not impaired.

If used for a second layer, provide one such clear coating composition is a clear one Coating, with regard to their impact resistance and their Crack resistance when exposed to environmental conditions  is improved due to the reinforcement of the Coating film and reducing stress by the polymer particles as the dispersion phase, and the due increased viscosity and thixotropy of Coating composition is prevented from itself to run on vertical surface parts of the substrate. The advantage of eliminating bleeding allows the Use of the composition to form thick layers ("high build coating").

When the clear coating composition, in particular the polymer particle dispersion of the invention and a Contains hardening agent, for a second layer in Coating process with two coating stages and one Burning stage is used, it is possible for the Base line as first layer one Coating composition, in particular the Polymer particle dispersion of the invention Contains curing agent and a pigment, or a Coating composition already for the application on plastics or metal substrates is known, too which can form coatings that are excellent are in terms of the appearance of the coating film (Clear gloss, surface smoothness, gloss and the like); the Weather resistance (retention of gloss, no Dullness, resistance, weather resistance, moisture resistance, hardenability and the like such known coating compositions are those which as carrier component aminoacrylic resins, aminoalkyd resins, Aminopolyester resins, acrylic polyol polyisocyanate resins of Two-pack type and the like. Included. The shape of this Coating compositions is not specifically limited and it can be any composition of organic Solution type, non-aqueous dispersion type, aqueous  Solution (dispersion) type, powder type, high type Solid content and the like. Be.

Examples of substrates used in the inventive Coating processes can not be coated specifically limited and include metallic substrates, Plastics, wood and the like. Examples of metallic Substrates are substrates of iron, copper, aluminum, zinc or alloys thereof and substrates of these metals, the by chemical conversion coating (Iron phosphate treatment, zinc phosphate treatment, Chromate treatment or the like) were surface-treated.

Substrates are representative of plastic substrates Polyurethane, polypropylene, polycarbonate or the like. Also Substrates made of metals, plastics, wood can be used or the like., which is a primed or electrolytic coated surface or over a Interlayer surface on a primed or have electrolytically coated substrate.

The coating composition for the base coat in the coating method according to the invention with two Coating steps and a baking step is preferred by spray coating, electrostatic coating or applied similar coating method. A preferred Thickness of the dried base coat is about 10 to about 30 μm. According to the invention, the clear Coating composition immediately after application the bottom line, or after the air drying thereof, or after half-hardening of the same by drying in hot air applied for a short period of time, i. H. she will not applied during the basic stroke or semi-hardened.  

The clear coating composition is preferably carried by Spray coating, electrostatic coating or the like applied. A preferred thickness of the dried clear Coating is about 20 to about 50 microns.

The conditions for baking the uncured first and second layer at the same time vary depending on on the type of coating compositions used for the first and second layers were used. It will, however preferably, the layers at a temperature of about 50 to about 180 ° C, preferably about 80 to about 160 ° C, about 10 to 40 minutes to heat.

The process of the invention leads to the best Results when the baseline composition and the clear Coating composition both the inventive Polymer particle dispersion and a polyisocyanate as Contain hardening agent. In this case, the Baseline composition and the clear Coating composition in terms of storage stability notable in the form of a single pack, and not only with regard to each of the above-mentioned aspects characteristic, but also under Low temperature bake conditions of about 70 to Cured about 80 ° C for about 20 to about 30 minutes.

The inventive method provides a two-layered Coating film, which in terms of hardness, adhesion, Weather resistance and more similar Coating film features and stands out in terms of the appearance of the coating film is excellent.

The present invention will be hereinafter referred to to the following examples, reference examples, Comparative Examples, Synthesis Examples, Formulation Examples  and manufacturing examples described in more detail. If Unless otherwise indicated, the parts and percentages are in the examples all parts by weight or percentages by weight.

Synthesis of the dispersion stabilizer Synthesis Example 1 Synthesis of the Dispersion Stabilizer (I)

The following components were in a four-necked flask given with a stirrer, an inlet for inert gas, a thermometer and a cooler was provided:

xylene 500 parts butyl 300 parts

N₂ gas was gradually pressed into the flask while the Mixture was heated to 110 ° C. A mix of the following Components (mixture of monomers and Polymerization initiator) was over a period of 4 hours added dropwise:

trimethylsiloxyethyl 300 parts styrene 100 parts n-butyl acrylate 160 parts methyl methacrylate 150 parts 2-ethylhexyl 280 parts acrylic acid 10 parts azobisisobutyronitrile 10 parts

The resulting mixture was aged for 30 minutes and a mixture of the following components was added dropwise added over a period of 1.5 hours:

butyl 200 parts azobisisobutyronitrile 5 parts

The mixture was aged for another 30 minutes. Subsequently, the following components were added:

p-tert-butylcatechol 0.15 parts glycidyl 16 parts dimethylaminoethanol 0.8 parts

The mixture was heated for 5 hours and allowed to cool End reaction, resulting in a solution of the  Dispersion stabilizer (I) led.

The solution of the dispersion stabilizer (I) had a content of 50% non-volatiles and a viscosity P-Q (Gardner, 25 ° C) and contained the Dispersion stabilizer with a number average of Molecular weight of 8,000, a hydroxyl number of 42 (relative on siloxy group) and on average about 0.7 polymerizable double bonds per molecule.

Synthesis Example 2 Synthesis of the Dispersion Stabilizer (II)

The same procedure as in Synthetic Example 1 was repeated. with the exception that the following mixture of monomers and Polymerization initiator was used, creating a solution of the dispersion stabilizer (II) was prepared:

trimethylsiloxyethyl 300 parts styrene 200 parts n-butyl acrylate 190 parts 2-ethylhexyl acrylate 300 parts acrylic acid 10 parts azobisisobutyronitrile 30 parts

The solution of the dispersion stabilizer (II) was 50% non-volatile components and had a viscosity L-M (Gardner, 25 ° C) and contained the dispersion stabilizer with a number average molecular weight of 6000, one Hydroxyl number of 42 (based on siloxy group) and an average of about 0.7 polymerizable double bonds per molecule.

Synthesis Example 3 Synthesis of the Dispersion Stabilizer (III)

The procedure of Synthesis Example 1 was repeated with the Except that instead of trimethylsiloxyethyl methacrylate Triphenylsiloxyethyl methacrylate was used, creating a Solution of the dispersion stabilizer (III) was obtained.  

The solution of the dispersion stabilizer (III) was 50% non-volatile components and had a viscosity R-S (Gardner, 25 ° C) and contained the dispersion stabilizer with a number average molecular weight of 8000, one Hydroxyl number of 22 (based on siloxy group) and an average of about 0.7 polymerizable double bonds per molecule.

Synthesis Example 4 Synthesis of the dispersion stabilizer (IV) without siloxy groups

The procedure of Synthesis Example 1 was repeated with the Except that instead of 300 parts of trimethylsiloxyethyl methacrylate 193 parts of 2-hydroxyethyl methacrylate, instead of 500 parts of xylene and 300 parts butyl acetate 446 parts xylene and 268 parts Butyl acetate and instead of 200 parts of butyl acetate 179 parts Butyl acetate were used, whereby a solution of the Dispersion stabilizer (IV) was obtained without siloxy groups.

The solution of the dispersion stabilizer (IV) had a content of non-volatiles of 50% and a viscosity O-P (Gardner, 25 ° C) and contained the dispersion stabilizer having a number average molecular weight of 7000, one Hydroxyl number of 42 and average about 0.7 polymerizable double bonds per molecule.

Example 1 Preparation of the dispersion (A)

The following components were in a four-necked flask given, which was provided with a stirrer and a condenser:

50% solution of the dispersion stabilizer (I) obtained in Synthesis Example 1 300 parts heptane 390 parts butyl 50 parts

The mixture was heated to 90 ° C and the following mixture  from monomers and polymerization initiator was over a Period of 4 hours added dropwise:

styrene 50 parts methyl methacrylate 200 parts acrylonitrile 50 parts hydroxyethyl methacrylate 50 parts azobisisobutyronitrile 3.5 parts

The resulting mixture was aged for 30 minutes and a Mixture of the following components was added dropwise over a Time span of 1.5 hours added:

butyl 70 parts azobisisobutyronitrile 1.75 parts

The mixture was aged for another 30 minutes and cooled, to finish the implementation.

The polymer particle dispersion thus obtained was white and stable and had a non-volatile content of 43%, a viscosity D-E (Gardner, 25 ° C) and a average particle size (measured by a Light scattering method) of 280 nm. The polymer particles in The dispersion was uncrosslinked and dissolved easily Acetone, if a small amount of the dispersion in acetone was poured.

example 2 Preparation of the dispersion (B)

The same reaction was carried out as in Example 1, with the exception that the following mixture of monomers and Polymerization initiator was used:

styrene 50 parts methyl methacrylate 256 parts acrylonitrile 30 parts glycidyl 7 parts methacrylic acid 7 parts azobisisobutyronitrile 3.5 parts

The polymer particle dispersion thus obtained was stable and had a non-volatile content of 43%, a viscosity C-D (Gardner, 25 ° C) and a average particle size (measured by a Light scattering method) of 230 nm.

The polymer particles in the dispersion (B) were highly crosslinked and gelled so that when diluted with acetone, Methyl ethyl ketone or a similar polar solvent were not solved or swollen.

example 3 Preparation of the dispersion (C)

The following components were in a four-necked flask of the same type as in Example 1, with a stirrer and a cooler was given given:

50% solution of the dispersion stabilizer (II) obtained in Synthesis Example 2 300 parts heptane 440 parts

The mixture was heated to 90 ° C and the following Components were added dropwise over a period of 4 hours admitted:

styrene 75 parts methyl methacrylate 200 parts acrylonitrile 25 parts hydroxypropyl methacrylate 50 parts azobisisobutyronitrile 3.5 parts

A mixture of the following components was added dropwise added within 1.5 hours:

butyl 70 parts azobisisobutyronitrile 1.75 parts

The mixture was aged for 30 minutes and 160 parts Heptane was under reduced pressure for concentration deducted.  

The polymer particle dispersion thus obtained was stable and had a non-volatile content of 50%, a viscosity L-M (Gardner, 25 ° C) and a average particle size (measured by a Light scattering method) of 320 nm.

The polymer particles in the dispersion (C) were not crosslinked and dissolved easily in acetone when a small amount of the Dispersion was poured into acetone.

example 4 Preparation of the dispersion (D)

The same procedure as in Example 1 was carried out with with the exception that instead of the 50% solution of Example 1 used dispersion stabilizer (I) in Synthesis example 3 obtained 50% solution of Dispersion stabilizer (III) was used, resulting in a white, stable dispersion (D) led. The dispersion (D) had a non-volatile content of 43%, a viscosity E-F (Gardner, 25 ° C) and an average Particle size (measured by a light scattering method) of 280 nm. The polymer particles in the dispersion were not crosslinked and dissolved easily in acetone when a small one Amount of dispersion was poured into acetone.

example 5 Preparation of the dispersion (E)

The reaction of Example 3 was repeated with the Exception that the following mixture of monomers and Polymerization initiator was used and no heptane was deducted reduced pressure:

styrene 50 parts methyl methacrylic 256 parts acrylonitrile 30 parts glycidyl 7 parts methacrylic acid 7 parts azobisisobutyronitrile 3.5 parts

The dispersion thus obtained was stable and had a content of non-volatiles of 43%, a viscosity C-D (Gardner, 25 ° C) and an average particle size (measured by a light scattering method) of 270 nm.

The polymer particles in the dispersion were highly cross-linked and gelled so that when diluted with a polar solvents, such as. As acetone, methyl ethyl ketone or Like. were not dissolved or swollen.

Comparative Example 1 Preparation of the dispersion (F) without siloxy groups

The procedure of Example 1 was repeated with the Except that instead of the 50% used in Example 1 Solution of the dispersion stabilizer (I) that in Synthesis Example 4 prepared 50% solution of the dispersion stabilizer (IV) resulting in a white, stable dispersion (F). led. The dispersion (F) had a content of non-volatile Constituents of 43%, a viscosity D-E (Gardner, 25 ° C) and an average particle size (determined by a light scattering method) of 280 nm. The Polymer particles in the dispersion were uncrosslinked and easily dissolved in acetone when a small amount of the Dispersion was poured into acetone.

Comparative Example 2

Isobutyl acetate (400 parts) and 400 parts of toluene were added Heating is refluxing. The following mixture of monomers and Polymerization initiator was dropwise over 3 hours added:

2-hydroxyethyl methacrylate 200 parts methyl methacrylate 400 parts ethyl acrylate 300 parts butyl acrylate 100 parts 2,2'-azobisisobutyronitrile 2 parts

The resulting mixture became 2 hours after the addition aged. The thus-obtained acrylic resin solution had a content on non-volatile constituents of 55%, a viscosity J and contained the resin having a hydroxyl number of 48 and one Number average molecular weight of about 7,000.

Comparative Example 3

Isobutyl acetate (400 parts) and 400 parts of toluene were added Heating is refluxing. The following mixture of monomers and Polymerization initiator was added dropwise via a Time span of 3 hours added:

2-hydroxyethyl methacrylate 170 parts styrene 100 parts isobutyl 520 parts 2-ethylhexyl 200 parts methacrylic acid 10 parts 2,2'-Azobisibutyronitril 2 parts

The resulting mixture became 2 hours after the addition aged. The thus-obtained acrylic resin solution had a content of non-volatiles of 55% and a viscosity I and contained the resin having a hydroxyl number of 41 and one Number average molecular weight of about 7,000.

Formulation Examples 1 to 8 and Comparative Formulation Examples 1 and 4

Coating compositions were replaced by a conventional Process from the components listed in Table 1 below the quantities listed therein to the properties the dispersions and the resin solutions used in Examples 1 to 4 and in Comparative Examples 1 to 3 were to be judged.

Production of test panels for use in behavioral testing

A cationic coating composition for the Electrocoating based on epoxy was electrolytically on a blunt steel plate of 0.8 mm thickness, which had been treated with zinc phosphate, applied to a Coating about 20 microns thick (after drying) too form. The coated steel plate became 20 minutes at 170 ° C long baked, sandpaper (# 400) polished and degreased by rubbing with petroleum benzine. On the coated steel plate was air-sprayed Intercoating Surface Treatment Agent (intercoat surfacer) for motor vehicles applied to a coating with a thickness of about 25 microns (after drying) to form. The coated steel plate became at 140 ° C for 30 minutes baked, sandpaper (# 400) polished and dried for drainage. The coated one Steel plate was then degreased with petroleum benzine and as Test panel used.

The coating compositions used in the Formulation Examples 1 to 8 and in the Comparative Formulation Examples 1 to 4 were prepared, were brought to a viscosity of 22 seconds (Ford cup no. 4, 25 ° C) and by an air pressure spray gun until to a thickness of about 30 microns (after drying) on the Test panel applied. The coated one Test panel was left at room temperature for 10 minutes and in an electric oven at 80 ° C for 30 minutes Baking process subjected (except that the Coating composition of Formulation Example 6 baked alone at 140 ° C for 30 minutes.).

The thus-baked coated test panels were tested for their coating film properties, with the results shown in the following Table 1, which also includes the results of the storage stability test Coating compositions based on a viscosity of 22 seconds (Ford cup # 4, 25 ° C) had been set, reproduces. The experiments regarding the  Coating film properties were 3 days after the Production of the coated test panels performed.

In Table 1, the comments (* 1) to (* 9) have the following Meaning:

• (* 1) Trademarks "BURNOCK DN-990":
  Product of Dainippon Ink and Chemicals, Incorporated, Japan, non-yellow discoloring type polyisocyanate prepolymer.
• (* 2) Trademarks "CYMEL 303":
  Product of Mitsui Toatsu Chemicals, Inc., Japan, methylated melamine resin.
• (* 3) Trademark "ETHYL SILICATE 40":
  Product of Colcoat Co., Ltd., Japan, a mixture of partial condensates of tetraethyl silicate.
• (* 4) Trademark "TIPURE R-960":
  Product of EI Du Pont de Nemours & Co., USA, rutile type titanium oxide.
• (* 5) Number of strokes with a solvent:
  Four pieces of gauze soaked with xylene and overlaid were attached to the friction bar of a rubbing tester. The friction bar was allowed to reciprocate on the surface of the coated test panel under a pressure of 4 kg / cm² for a length of 5 cm. The values in Table 1 represent the number of back and forth strokes that resulted in exposure of the intermediate coat.
• (* 6) impact resistance:
  The experiment was carried out in an atmosphere at 20 ° C according to the standard JIS-K-5400. The coated test panel was inserted between a test panel support and an element having a rounded contact surface (0.5 inch diameter) that was in contact with the coated surface of the test panel. A weight of 500 g was dropped on the element. The displayed value is the maximum height (in cm) at which the dropped weight did not damage the coating film.
• (* 7) Weather resistance:
  The coated test panel was tested for 1200 hours with a Sunshine Weather O-Meter and washed with water. Then the retention of gloss (in percent) was determined at a gloss angle reflection of 60 ° C and evaluated according to the following ratings:
  A: 81% or above
  B: 70 to 81%
• (* 8) Resistance to acid:
  The coated test panel, whose surrounding edges were sealed, was immersed in a 40% aqueous solution of 30 ° C warm sulfuric acid for 5 hours, and after replacement, the appearance of the coated surface was determined. The appearance was judged according to the following ratings:
  A: no change
  B: dipped part a little dull
• (* 9) Shelf life of the diluted coating composition:
  A coating composition adjusted to a certain viscosity was placed in a glass bottle, which was then hermetically sealed. The change in viscosity was determined after one week of storage at 50 ° C (Ford cup # 4, 25 ° C). Shelf life was assessed according to the following ratings:
  A: Viscosity change of less than 3 seconds
  B: Viscosity change of 3 to 10 seconds
  C: Gelled

Reference Example 1

A four-necked flask equipped with a stirrer, an inlet for Inert gas, a thermometer and a cooler, was charged with 200 parts of a monomer mixture of 200 parts Trimethylsiloxyethyl methacrylate, 400 parts of methyl methacrylate, 300 parts of ethyl acrylate and 100 parts of butyl acrylate, 500 parts Toluene, 200 parts isobutyl acetate, 5 parts Azobisisobutyronitrile (AIBN) and 10 parts tert-butyl perbenzoate (t-BPB) filled. The mixture was 1 hour kept at 90 ° C and within 30 minutes on Heated to 115 ° C. A mixture of the remaining parts (800 Parts) of the monomer mixture, 300 parts of isobutyl acetate, 10 parts t-BPB and 5 parts AIBN was within 3 hours at 115 ° C was added dropwise and the mixture was at the same temperature for 10 hours, resulting in a Resin solution containing a non-volatile content Constituents of 50% and a viscosity (Gardner, 25 ° C) H and the resin with a number average of Molecular weight of 14,000 and a hydroxyl number of 28 (based on siloxy group).

Reference Example 2

The procedure of Reference Example 1 was repeated, with with the exception that a monomer mixture of 260 parts Trimethylsiloxyethyl methacrylate, 200 parts styrene, 470 parts n-butyl methacrylate and 70 parts of butyl acrylate instead of Monomer mixture used in Reference Example 1, was used. The resin solution thus obtained had a Non-volatile content of 50%, one Viscosity B-C (Gardner, 25 ° C) and contained the resin with a Number average molecular weight of 9000 and one Hydroxyl number of 36 (based on siloxy group).

Production Examples 1 to 22

Preparation of coating compositions for the  Base coat and the clear coating compositions for the topcoat Coating compositions for a base coat and clear Coating compositions for a topcoat were prepared by conventional methods from the dispersions or Resin solutions which in Examples 1 to 5, the Comparative Examples 1 to 3 and Reference Examples 1 and 2, using the other components, those in the following Tables 2 and 3, which are also the corresponding quantities are listed. These Coating compositions have been described in terms of their Storage stability examined, with the in Tables 2 and 3 obtained results were obtained.

Have the comments * 10 to * 15 in Tables 2 and 3 the following meaning:

• (* 10) Trademark "Alpaste 55-519":
  Product of Toyo Aluminum KK, Japan, paste of aluminum powder
• (* 11) Storage stability:
  The coating compositions, diluted to a viscosity of 25 seconds (Ford cup # 4, 25 ° C), were stored at 50 ° C for 1 month in a container that was hermetically sealed to prevent contact with ambient air. Shelf life was assessed according to the following ratings:
  A: Viscosity increase of less than 3 seconds
  B: Viscosity increase of 3 to 10 seconds
  C: Gelled
• (* 12) Trademark "Tinuvin 900":
  Product of Ciba-Geigy Ltd., Switzerland, UV absorber
• (* 13) Trademark "Tinuvin 144":
  Product of Ciba-Geigy Ltd., Switzerland, light stabilizer.
• (* 14) Trademark "Aerozil No. 200":
  Product of Nippon Aerozil Co., Ltd., Japan, finely divided silica powder.
• (* 15) Maximum coating film thickness at which no Bleeding was detected.

A clear coating composition for a topcoat, diluted to a viscosity of 25 seconds (Ford cup # 4, 25 ° C), was air sprayed onto a tin plate (10 mx 50 cm) placed in a vertical Position was applied, to form a coating film with a sloping thickness of 10 to 100 microns (after drying). The coated panel was allowed to dry for 8 minutes, then baked for 30 minutes at 90 ° C and then examined to determine the thickness of the portion of the coating that had begun to run.

Examples 6 to 17 and Comparative Examples 4 to 10

Test panels were made the same way made, as in the testing of Coating properties of the above in the Formulation Examples and Comparative Formulation Examples prepared coating compositions, d. H. by Priming a blunt steel plate, connecting Cover the primed steel plate with one Interlayer surface treatment and degreasing the coated plate with petroleum benzine.

Each of those prepared in Preparation Examples 1 to 11 Coating compositions for a base coat was to a viscosity of 15 seconds (Ford Cup No. 4, 25 ° C) set and with an air pressure spray gun on one Test panel applied to a base coat with a Thickness of 15 microns (after drying) to form. The coated one Test panel became at room temperature for 3 minutes let it dry. Then each became clear Coating compositions for a topcoat, which in Production Examples 12 to 21 had been prepared, to a viscosity of 25 seconds (Ford Cup No. 4, 25 ° C) set and with an air pressure spray gun on the Applied to a clear topcoat with a base coat Thickness of about 30 microns (after drying) to form. The coated test panel was left at room temperature for 10 minutes allowed to dry for a long time and to cure in one electric oven baked. The baking conditions were as follows: In Examples 8, 14 and 17 and in Comparative Example 10, the coated Test panels baked at 140 ° C for 30 minutes and in the other examples and comparative examples baking at 80 ° C for 30 minutes.

The coated test panels thus obtained were in terms of their coating film properties 3 days after  the production of the coated test panels by the following procedures examined. The test results are in the following Tables 4 and 5 listed.

The notes * 16 to * 23 in Tables 4 and 5 have the the following meaning:

• (* 16) Marbling in the metallic texture:
  The coating surface (30 x 45 cm) of the coated test panel was examined by visual inspection for marbling. The appearance was judged according to the following ratings:
  A: The metallic pigment was uniformly oriented in the coating in parallel and the coating surface showed no marbling.
  B: Marbling was observed on less than one third of the area.
  C: One-third to one-half of the coating surface showed marbling.
  D: Marbling was detected on almost the entire surface of the coating.
• (* 17) Metallic whiteness:
  The metallic whiteness was determined by a color difference meter and the obtained reading, the L value, was shown. A larger value indicates a higher whiteness and thus a more favorable result.
• (* 18) pencil hardness:
  The coated surface of the coated test panel was evaluated for scratch resistance using a pencil (trademark "Mitsubishi Uni"), product of Mitsubishi Pencil Co., Ltd., Japan) according to JIS-K-5400.
• (* 19) Liability:
  The coated test panel was cut crosswise on the substrate surface (parallel cuts at a distance of 2 mm each) to form 100 squares. A cellophane adhesive tape was adhered to the coating surface and then peeled off. The appearance of the coating surface after peeling was examined with the naked eye. The result is given as the number of unreduced squares per 100 squares.
• (* 20) Moisture resistance:
  The coated test panel was placed in a moisture resistance tester at approximately 50 ° C and approximately 100% relative humidity and removed after 14 days. Then, the appearance of the coating surface was evaluated according to the following ratings:
  A: No change
  B: Slightly shrunk but no blistering
  C: slight blistering
  D: Bubbles here and there on the entire surface of the coating.
• (* 21) Resistance to boiling water:
  The coated test panel was immersed in boiling water of 98 to 100 ° C for 3 hours and the appearance of the coating surface after removal was evaluated according to the following ratings:
  A: No change
  B: Slightly shrunk but no blistering
  C: slight blistering
  D: Bubbles here and there on the entire surface of the coating.
• (* 22) Acid resistance:
  The coated test panel was immersed in 40% sulfuric acid at a temperature of 30 ° C for 5 hours and the appearance of the coating surface after replacement was evaluated according to the following ratings:
  A: No change
  B: Slightly shrunken, but neither discolored nor blistered.
• (* 23) weather resistance:
  An accelerated weathering test was conducted using a QUV Weather O-Meter manufactured by The Q Panel Company. An experimental cycle was carried out under the following conditions:
  Irradiation with ultraviolet light: 16 hours, 60 ° C
  Water condensation: 8 hours, 50 ° C.
  Each coated test panel was checked after 3000 hours (125 cycles). The assessment was conducted with the following ratings:
  A: The coating surface showed no cracks or peeling and retained its gloss by 80% or more.
  B: The coating surface showed no cracks or peeling and kept its gloss from 50 to 80%.
  C: Cracks developed within 2,000 to 2,500 hours and the gloss was retained less than 50% within 3,000 hours.

Table 4

Claims (11)

A dispersion of polymer particles prepared by dispersion-polymerizing at least one ethylenically unsaturated monomer in the presence of a dispersion stabilizer in an organic solvent in which the ethylenically unsaturated monomer is soluble but the polymer particles produced by dispersion polymerization of the monomer are insoluble, characterized in that the dispersion stabilizer is selected is from:

• (i) a siloxy-containing copolymer prepared by copolymerizing from about 5 to about 60% by weight of a polymerizable unsaturated monomer A having in its molecule at least one polymerizable unsaturated group and at least one carbon atom-bonded siloxy group represented by the following formula in which R₁ and R₂ are each C _1-18 alkyl, phenyl, allyl, Cl, H or F and R₃ is C _1-18 alkyl, phenyl or allyl, and about 40 to about 95% by weight of a polymerizable unsaturated monomer B which is copolymerizable with the monomer A, wherein the siloxy-containing copolymer has a number average molecular weight of about 1,000 to about 35,000; and or
• (ii) a modified copolymer having one or more radically polymerizable unsaturated double bonds introduced into the siloxy-containing copolymer.

2. Dispersion according to claim 1, characterized in that the polymerizable unsaturated monomer A is selected from at least one of the following monomers:
Trimethylsiloxyethyl acrylate or methacrylate,
Trimethylsiloxypropyl acrylate or methacrylate,
Trimethylsiloxybutyl acrylate or methacrylate,
Triethylsiloxyethyl acrylate or methacrylate,
Tributylsiloxypropyl acrylate or methacrylate and
Triphenylsiloxyethyl acrylate or methacrylate. 3. Dispersion according to one of claims 1 and 2, characterized in that the polymerizable unsaturated monomer B is selected from at least one monomer of the following group: C₁-C₂₂-alkyl esters of acrylic acid or methacrylic acid, styrene, vinyltoluene, t-butylstyrene, α - Methylstyrene, glycidyl acrylate or methacrylate, 2-ethoxyethyl acrylate or methacrylate, acrylonitrile or methacrylonitrile, cyclohexyl acrylate or methacrylate, unsaturated carboxylic acids, diesters of maleic acid or fumaric acid and monohydric C₁-C₁₈ alcohols, acrylamides or methacrylamides, N, N-Di-C₁- C₄-alkylamino-C₁-C₄-alkyl acrylate or methacrylate, phosphoric acid group-containing acrylate or methacrylate, vinyl acetate and fluorine-containing vinyl monomers. 4. Dispersion according to one of claims 1 to 3, characterized characterized in that the dispersion stabilizer a modified siloxy-containing copolymer is that an average of 0.1 to 1.5 radically polymerizable unsaturated double bonds in the molecule of Having siloxy-containing copolymers. 5. Dispersion according to one of claims 1 to 4, characterized characterized in that the ethylenically unsaturated monomer  is a monomer or monomer mixture that is about 40 wt .-% or more of an ester of acrylic acid or Contains methacrylic acid. 6. Dispersion according to one of claims 1 to 5, characterized characterized in that the amount of the dispersion stabilizer about 5 to 70 wt .-%, based on the Total amount of dispersion stabilizer and the ethylenic unsaturated monomers. 7. Dispersion according to one of claims 1 to 6, characterized characterized in that the total concentration of Dispersion stabilizer and ethylenically unsaturated Monomers about 30 to about 70 wt .-% is. A coating process comprising two coating steps and a bake step comprising applying a coating composition containing pigment to a substrate to form a first layer, then applying a clear coating composition to the first layer to form a second layer and curing the two uncured layers by simultaneously Heating, characterized in that the first layer coating composition and / or the second layer clear coating composition comprises:

• (1) A dispersion of polymer particles prepared by dispersion-polymerizing at least one ethylenically unsaturated monomer in the presence of a dispersion stabilizer in an organic solvent in which the ethylenically unsaturated monomer is soluble but the polymer particles produced by dispersion polymerization of the monomer are insoluble, with the dispersion stabilizer being selected out:
  • (i) a siloxy-containing copolymer prepared by copolymerizing from about 5 to about 60% by weight of a polymerizable unsaturated monomer A having in its molecule at least one polymerizable unsaturated group and at least one carbon atom-bonded siloxy group represented by the following formula in which R₁ and R₂ are each C _1-18 alkyl, phenyl, allyl, Cl, H or F and R₃ is C _1-18 alkyl, phenyl or allyl, and about 40 to about 95% by weight of a polymerizable unsaturated monomer B which is copolymerizable with the monomer A, wherein the siloxy-containing copolymer has a number average molecular weight of about 1,000 to about 35,000; and or
  • (ii) a modified copolymer having one or more radically polymerizable unsaturated double bonds introduced into the siloxy-containing copolymer, and
• (2) a curing agent reactive with hydroxy groups.

9. The method according to claim 8, characterized in that the Curing agent is a polyisocyanate. 10. The method according to claim 9, characterized in that both the coating composition for the first Layer as well as the clear coating composition for the second layer, coating compositions  which are the said dispersion of polymer particles and containing said curing agent. 11. The method according to any one of claims 8 to 10, characterized characterized in that the coating compositions by heating to a temperature of about 70 to be cured at about 80 ° C.