JPH0135861B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a coating composition, and more particularly to a coating composition containing crosslinked copolymer fine particles useful as an automotive or other decorative coating. In recent years, so-called high-solids coating compositions in which cross-linked polymer fine particles called microgels are dispersed in a coating composition containing a resin vehicle have been attracting attention in automotive painting and other fields due to their workability and coating performance. . This microgel particle is made of a polymer that is crosslinked to a certain extent and is insoluble in the organic solvent for the paint to be dispersed, and the particle size is microscopic.
It must be stably dispersed in the composition. Various methods have been proposed to produce microgels, one of which is to emulsion polymerize an ethylenically unsaturated monomer with a crosslinkable copolymerizable monomer in an aqueous medium to form a fine particle copolymer. Microgel particles are obtained by removing water by manufacturing, solvent replacement, azeotropy, centrifugation, filtration, drying, etc., and the other is a non-gel particle that dissolves monomers such as aliphatic hydrocarbons but does not dissolve polymers. This method was called the NAD method, in which an ethylenically unsaturated monomer and a crosslinkable copolymerizable monomer were reacted in an aqueous organic medium, and the resulting fine particle copolymer was fractionated. In this internal emulsion polymerization method, relatively fine particles can be easily obtained, and the heat of reaction can be easily removed, making it suitable for industrial use. However, it only requires an operation to remove water from the emulsion product. In order to disperse the monomers to be copolymerized in an aqueous medium, an emulsifier, which is a relatively low molecular weight compound mainly composed of anionic or cationic surfactants, is required. Since it is attached to the polymer, it cannot be avoided that even when a coating film is formed, it will be mixed into the coating film and adversely affect the coating performance. In addition, an aqueous medium is used for emulsion polymerization, and volatile organic solvents such as aromatic solvents are used for coatings.
It is difficult to use emulsifiers and dispersants that are useful for particle dispersion during emulsion polymerization for dispersing microgels in coating compositions, and some kind of ingenuity is required for stable dispersion of microgels in coating compositions. On the other hand, the NAD method uses a solvent that is non-aqueous and does not dissolve the polymer, so it can be added directly to the coating composition without separating the microgels, and the microgels can also be separated relatively easily. However, it has many problems different from emulsion polymerization methods. First, when copolymerizing a monomer with an ethylenically unsaturated group and a crosslinkable copolymerizable monomer in a nonaqueous organic liquid, a special dispersion stabilizer is required to form a microgel. It is a point. Usually, this dispersion stabilizer is a graft copolymer consisting of a polymer main chain that is not solvated by the organic liquid of the reaction medium and a polymer chain that is solvated by the organic liquid that is bonded to the main chain as a side chain. However, it is necessary to carefully select the graft copolymer by considering its affinity for polymer particles and affinity for solvents, depending on the type of monomer to be microgelled, the type of non-aqueous organic liquid to be used, etc. It is. Furthermore, when preparing microgels, a low polar solvent mainly composed of aliphatic hydrocarbons is usually used as the organic liquid, and relatively highly polar organic solvents are used for making paints. A problem with stabilizers is that they are almost ineffective in stabilizing the dispersion of microgels in coating compositions. One of the solutions to this problem is, for example,
Nos. 133234; 53-133235; 53-133236; 54-150439, etc., after preparing microgels, monomers that should form a polymer having the same composition as the film-forming polymer used for coating are placed on microgel particles. We are conducting polymerization and modification of microgels. As described above, there are various problems in the conventional production of microgels and in the preparation of high-solids coating compositions using the microgels, and both the emulsion polymerization method and the NAD method have advantages and disadvantages as methods for producing microgels, and they are not suitable for industrial use. At present, a fully satisfactory high solids coating composition has not been obtained. The present inventors previously determined that the formula

[Formula] (In the formula, R is a C ₁ to C ₆ alkylene or phenylene group that may have a substituent, and Y is -
Alkyd resins, polyester resins, acrylic resins, melamine resins, polyether resins, etc. that have a group represented by COOH or -SO ₃ H) have amphoteric groups in their molecules, so they have unique reactivity, surface activity, and electrochemistry. It was discovered that it is extremely useful as an emulsifier or dispersant when carrying out emulsion polymerization of monomers having ethylenically unsaturated groups in an aqueous medium in the presence of a polymerization initiator. I filed an application (patent application 1982-
71864). The above invention uses a monomer having two or more radically polymerizable ethylenically unsaturated groups in the molecule as one type of ethylenically unsaturated monomer, and also contains the amphoteric group in the molecule. The emulsion resin is obtained by copolymerizing polymerizable monomers in an aqueous medium using a water-soluble resin containing the emulsifier as an emulsifier. Or, by copolymerizing a monomer that does not contain a protective colloid and has two or more radically polymerizable ethylenically unsaturated groups in the molecule, the water resistance, solvent resistance, gloss, etc. of the coating film are improved. The focus was on points that could be improved. The present inventors found that the resin particle diameter of the emulsion resin is extremely fine, approximately 0.02 to 0.5μ, and that the resin separated from the emulsion by water removal also
Approximately 40μ, although some agglomeration is seen due to the processing method.
The resin itself has a particle size that does not interfere with paint film formation, and can be easily refined by mechanical means if desired.The resin itself is crosslinked and insoluble in common paint solvents. Find out things, etc.
Furthermore, we learned that a fine particle polymer can be obtained in which a resin containing amphoteric groups having special interfacial properties is attached to the surface, and that this is extremely suitable as a dispersed fine particle polymer for high solids coating compositions. Furthermore, we continued our research on methods for preparing fine particle polymers, etc., and were able to complete the present invention. That is, according to the present invention, a film-forming polymer (A) having a functional group capable of reacting with a crosslinking agent, a volatile organic liquid diluent supporting the polymer;
(B), polymer fine particles (C) that are insoluble and stably dispersed in the combination of the polymer and diluent, and a crosslinking agent (D) that is dissolved in the diluent; Polymer fine particles (C) have a formula in the molecule.

[Formula] (In the formula, R is a C ₁ to C ₆ alkylene or phenylene group that may have a substituent, and Y is -
Crosslinking obtained by copolymerizing two or more monomers having α,β-ethylenically unsaturated groups in an aqueous or organic medium in the presence of a resin having a group represented by COOH or -SO ₃ H) A coating composition is provided that is a copolymer particulate. The film-forming polymer having a functional group capable of reacting with a crosslinking agent used in the present invention may be any known film-forming polymer such as an acrylic resin, an alkyd resin, or a polyester resin having a functional group such as a hydroxyl group or a carboxyl group. These usually have an acid value of 0.5-60, a hydroxyl value of 20-200,
It has a number average molecular weight of about 500 to 10,000. These polymers are commonly used in combination with crosslinking agents to effectuate or facilitate curing. Suitable crosslinking agents include diisocyanates, diepoxides, aminoplast resins, etc., which are usually dissolved in the polymer diluent and react with the functional groups of the film-forming resin during or after coating to form a three-dimensional cured coating. Forms a film. Particularly preferred crosslinking agents are melamine-formaldehyde condensates in which a substantial proportion of the methylol groups have been etherified by reaction with butanol or methanol. The above-mentioned film-forming polymer can be present in the diluting liquid by being dissolved or decomposed, or can be present in a partially dissolved or partially dispersed manner. In this case, volatile organic liquids are used, typically aromatic hydrocarbons such as toluene, xylene, various petroleum fractions containing aromatics; esters such as butyl acetate, ethylene glycol diacetate, 2-ethoxyethyl acetate. Ketones such as acetone, methyl isobutyl ketone, etc.; Alcohols such as butyl alcohol;
It can be an aliphatic hydrocarbon or a mixture thereof. The coating composition of the present invention further contains, as the most characteristic part, special polymer fine particles stably dispersed in the film-forming polymer-diluent-crosslinking agent system. Because these polymer particles are crosslinked copolymers of ethylenically unsaturated monomers, they are insoluble in the combination of film-forming polymer and organic diluent, and as a result of their manufacturing process, they are hydrophilic and non-philic. A special amphoteric group-containing resin with various affinity properties that is oily and adaptable to various solvents of different polarity is supported on the surface of the crosslinked copolymer fine particles, and does not require any treatment. are stably dispersed in the combination. Insolubility of the polymer particles in the combination of film-forming polymer and diluent is achieved by making the polymer a crosslinked copolymer, so that the copolymerizable monomer to be polymerized is Selectively use at least one type of monomer having two or more radically polymerizable ethylenically unsaturated groups, or two types of ethylenically unsaturated monomers each carrying groups that can react with each other. , at least one copolymerizable monomer other than these is copolymerized. Therefore, when the present specifier refers to "two or more α,β-ethylenically unsaturated monomers",
It should be understood that the above-mentioned monomers for crosslinking are also included as essential monomer components. Monomers having two or more radically polymerizable ethylenically unsaturated groups in the molecule (hereinafter referred to as polyfunctional monomers) include polymerizable unsaturated monocarboxylic acid esters of polyhydric alcohols, polybasic Examples include polymerizable unsaturated alcohol esters of acids and aromatic compounds substituted with two or more vinyl groups, examples of which include the following compounds. Ethylene glycol diacrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, 1,4-butanediol dimethacrylate acrylate, neopentyl glycol diacrylate, 1,6-hexanediol diacrylate,
Pentaerythritol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, glycerol dimethacrylate,
Glycerol diacrylate, glycerol allyloxy dimethacrylate, 1,1,1-trishydroxymethylethane diacrylate, 1,1,
1-trishydroxymethylethane triacrylate, 1,1,1-trishydroxymethylethane dimethacrylate, 1,1,1-trishydroxymethylethane trimethacrylate, 1,1,
1-trishydroxymethylpropane diacrylate, 1,1,1-trishydroxymethylpropane triacrylate, 1,1,1-trishydroxymethylpropane dimethacrylate, 1,
1,1-trishydroxymethylpropane trimethacrylate, triallyl cyanurate, triallyl isocyanurate, triallyl trimellitate, diallyl terephthalate, diallyl phthalate and divinylbenzene. In addition, two groups each carrying a group that can react with each other
Examples of monomers having ethylenically unsaturated groups include epoxy group-containing ethylenically unsaturated monomers such as glycidyl acrylate and glycidyl methacrylate, and carboxyl group-containing ethylenically unsaturated monomers such as acrylic acid, methacrylic acid, and crotonic acid. Monomers are the most representative, but mutually reactive groups are not limited to these.
For example, various compounds have been proposed, such as amine and carbonyl, epoxide and carboxylic acid anhydride, amine and carboxylic acid chloride, alkyleneimine and carbonyl, organoalkoxysilane and carboxyl, hydroxyl and isocyanate, etc., and the present invention broadly includes these. It is something to do. In the present invention, in addition to these crosslinkable monomers, any α,β-ethylenically unsaturated monomer is used as a copolymerization component, and these monomers have one polymerizable group in the molecule. Monomers can be broadly classified into the following groups. () Carboxyl group-containing monomers, such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, etc. () Hydroxyl group-containing monomers, such as 2-hydroxyethyl acrylate, hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, allyl alcohol,
Metaallyl alcohol etc. () Nitrogen-containing alkyl acrylates or methacrylates, such as dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, etc. () Polymerizable amides, such as acrylamide,
methacrylic acid amide etc. () Polymerizable nitriles, such as acrylonitrile and methacrylonitrile. () Alkyl acrylate or methacrylate, such as methyl acrylate, methyl methacrylate, ethyl acrylate, n-butyl acrylate, n-butyl methacrylate, 2
- Ethylhexyl acrylate, etc. () Polymerizable aromatic compounds, such as styrene, α
-Methylstyrene, vinyltoluene, t-butylstyrene, etc. () α-olefins, such as ethylene, propylene, etc. () Vinyl compounds, such as vinyl acetate, vinyl propionate, etc. () Diene compounds, such as butadiene, isoprene, etc. These monomers may be used alone or in combination. In the present invention, two or more types of α, β-
When ethylenically unsaturated monomers (including polyfunctional monomers, etc.) are present in aqueous or organic media,

[Formula] (In the formula, R is a C ₁ to C ₆ alkylene or phenylene group that may have a substituent, and Y is -
It is copolymerized in the presence of a resin having a group represented by COOH or -SO ₃ H). formula in the molecule

Examples of resins having groups represented by the formula include alkyd resins, polyester resins, modified epoxy resins, acrylic resins, melamine resins, and polyether resins having such groups. The above formula

[Formula] The group is

[Formula] Ma Taha

It can also be expressed as an amphoteric group such as the following formula: Resins having such an amphoteric group exhibit unique behavior in terms of reactivity, surface activity, electrochemical properties, etc. Alkyd resins and oil-free polyester resins having such amphoteric groups in their molecules are described in Japanese Patent Application No. 110865-1982 and Japanese Patent Application No. 56048-1982 filed by the present inventors. Alkyd resins and polyester resins are characterized by using polybasic acids and polyhydric alcohols as essential components to generate continuous ester chains.
Formula with some of the polyhydric alcohol components (In the formula, R ₁ is an alkyl group having at least one hydroxyl group; R ₂ and R ₃ are the same or different and are hydrogen or an alkyl group that may have a substituent; A may have a substituent; be
Alkyd resins or polyester resins having the above-mentioned amphoteric groups can be produced by replacing them with C ₁ -C ₆ alkylene groups or phenylene groups. For details, please refer to the above-mentioned patent applications No. 54-110865 and No. 56048 filed by the present inventors.
See issue. In the present invention, among these alkyd or polyester resins having amphoteric groups, the acid value is 30 to 30.
150, especially 40-150, number average molecular weight 500-5000,
In particular, it is preferable to use a number between 700 and 3000. formula

A modified epoxy resin having the group [Formula] in its molecule is described in Japanese Patent Application No. 116293/1983 by the present inventors. Generally, epoxy resin has a formula at the end. (in the formula, R ₄ and R ₅ are each hydrogen or methyl group), and the terminal group has the formula R ₆ -NH-A-SO ₃ M () (in the formula, R ₆ is an epoxy group). The oxirane ring is cleaved by reacting an alkyl group that may have an unreactive substituent, M is an alkali metal or ammonium group, and A is the same as above, and some of the terminal groups of the epoxy resin have the formula A modified epoxy resin is obtained. The hydrophilicity of the modified epoxy resin increases in proportion to the degree of substitution of the amphoteric group of the formula () in the epoxy resin. For details, see the aforementioned Japanese Patent Application No. 116293/1983. formula

[Formula] Regarding the acrylic resin having a group in the molecule, the present inventors' patent application No. 123899/1989,
No. 53-125996, No. 47651, No. 55-47, and
The formula described in No. 55-47652 (In the formula, R ₇ , R ₈ , R ₉ , R ₁₀ are H, CH ₃ ,
C ₂ H ₅ ; R ₁₁ is H or a C ₁ to C ₂₀ alkyl group that may contain -SO-, -COO-, or -O- in the chain; ; R ₁₂ is -OH group, -SH group, -SR ₁₃ group (R ₁₃ is C ₁
~ C ₄ alkyl group) and one or more C ₁ ~
C ₁ ~ which may be substituted with C ₄ alkyl group
is a _C12 alkylene group; A is a COOH group or
SO ₃ H group) or formula (In the formula, R ₁₄ , R ₁₅ , R ₁₆ are each H or C ₁ to _{C 6}
is an alkyl group; R ₁₇ is H or -SO-
a _C1 to _C20 alkyl group which may contain either a group, -COO-, or -O-, or R ₁₈ is a C ₂ -C ₁₂ alkylene group optionally substituted with one or more C ₁ -C ₆ alkyl groups) or the formula (In the formula, R ₁₉ , R ₂₀ , and R ₂₁ are each the same or different and are H or CH ₃ ; R ₂₂ has at least one hydroxyl group and may also contain an -O- or -COO- group in the alkyl skeleton. A certain C ₁ - C ₂₀ alkyl group; R ₂₃ has at least one hydroxyl group and -O- or -COO in the alkyl skeleton
A _C1 - _C20 alkyl group or H or a _C1 - _C20 alkyl group which may contain -; _R24 is basically represented by ( _CH2 ) _o (n is 1-6) and is substituted alkylene group; A is COO or SO ₃ ) or the formula (In the formula, R ₂₅ , R ₂₆ , and R ₂₇ are each the same or different and are H or CH ₃ ; R ₂₈ and R ₂₉ are each the same or different and are C ₁ to _{C 20} -O- or -COO
an alkyl group or a cycloalkyl group that may contain -, or R ₂₈ and R ₂₉ can be combined to form a heterocycle containing an N atom; R ₃₀ is basically (CH ₂ ) _o (n is an alkylene group represented by 1 to 6) and may be substituted; A is COO
or _SO3 ); and a hydroxyl group-containing monomer, a carboxyl group-containing monomer, a glycidyl group-containing monomer, an alkyl acrylate or methacrylate, a nitrogen-containing alkyl At least one polymerizable monomer selected from the group consisting of acrylates or methacrylates, polymerizable amides, polymerizable nitriles, polymerizable aromatic compounds, α-olefin compounds, vinyl compounds, and diene compounds and a conventional radical polymerization method. It is produced by solution polymerization in an organic solvent. For details of the above-mentioned polymerizable amino acid compound, please refer to the above-mentioned patent application No. 53-123899 of the present inventors,
No. 53-125996, No. 55-47651, No. 47652 No. 53-125996, No. 53-125996, No. 55-47652, also in the molecule.

[Formula] For details of the acrylic resin having the group, please refer to the patent application filed by the present inventors in 1982-
See No. 71864. In the present invention, it is preferable to use, among these acrylic resins having amphoteric groups, those having an acid value of 30 to 180, particularly 40 to 160, and a number average molecular weight of 500 to 10,000, particularly 700 to 6,000. formula

[Formula] For melamine resins that have a group in the molecule, the alcohol in the reaction component has the formula or or (In the formula, R ₃₄ is -O- or - in the alkyl skeleton)
A _C1 - _C20 hydroxyalkyl group that may contain COO-; _R35 is a _C1 - _C20 hydroxyalkyl group or lower alkyl group that may contain -O- or -COO- in the alkyl skeleton; R ₃₆ is H or a methyl group) Using at least one hydroxyl group-containing aminosulfonic acid type zwitterionic compound, mixed with melamine and formalin, and manufactured according to the reaction conditions and method used in ordinary melamine resin manufacturing. be able to. Regarding such usual reaction conditions and methods, see, for example, Kyozo Kitaoka, "Introduction to Synthetic Resins for Paints" (May 25, 1974, published by Kobunshi Kankokai, 134-
Perform according to the contents described on page 139). For details of the above-mentioned hydroxyl group-containing aminosulfonic acid type zwitterionic compound, see Japanese Patent Application No. 107624/1983 by the present inventors. formula

[Formula] Regarding the polyether resin having the group in the molecule, the present inventors' patent application
As described in issue 116293, the formula (in the formula, R ₃₁ and R ₃₂ are hydrogen or methyl groups, respectively),
A compound of the formula R ₃₃ -NH-A-SO ₃ M () (in the formula, R ₃₃ is a substituent that may have a substituent that does not react with an epoxy group; M is an alkali metal or ammonium group; A is the same as above) By reacting with A modified polyether type epoxy resin is obtained. Various polyether type epoxy resins are known and commercially available, and they can be obtained by reacting polyhydric phenols or polyhydric alcohols other than bisphenol A with halohydrin. For details, see the aforementioned Japanese Patent Application No. 116293/1983. All of the resins mentioned above have characteristic features in their molecules.

It has an amphoteric group of the formula and can be prepared to be either water-soluble or organic solvent-soluble. In the case of a water-soluble resin, this means that the α, β-
It is an excellent emulsifier and dispersant in the emulsion polymerization of ethylenically unsaturated monomers, and therefore crosslinked polymer fine particles can be produced without using ordinary emulsifiers. The polymerization is preferably carried out by dropping a monomer mixture in a predetermined ratio into an aqueous medium containing the amphoteric resin described above in the presence of a polymerization initiator. It is sufficient to use the amphoteric resin in an amount of 0.3% to 8%, preferably 0.5 to 6%, based on the total weight of the monomer mixture. In addition, a polyfunctional monomer for crosslinking that is present in two or more α,β-ethylenically unsaturated monomers to be copolymerized, or two types each carrying groups that can react with each other. Regarding the amount of unsaturated monomers, it is sufficient to select them in the range from 0.01 to 20% by weight, preferably from 0.1 to 10% by weight of the total monomers. However, this is not critical and should be selected to provide sufficient crosslinking so that the resulting particulate copolymer does not dissolve in the combination of film-forming polymer and organic diluent. It is. Usually, the insolubility of this fine particle polymer is determined by adding 1% by weight of the fine particles to an organic diluent such as tetrahydrofuran, shaking for 30 minutes, and then shaking at 17,000 rpm.
If the microparticles are acceptably insoluble in the diluent alone, centrifuge for 30 minutes at pm, remove the supernatant, dry weigh the residue, and compare the result to the original weight. It is also determined to be insoluble in the film-forming polymer and diluent combination. The water used is preferably used in such a proportion that the nonvolatile content of the obtained emulsion resin is 2 to 65%, preferably 20 to 60%, and furthermore, in order to help dissolve the resin, it is necessary to use a water that is compatible with its oxidation. It is preferable to include a certain amount of base. Alkali hydroxide, ammonia, and organic amines can be used as the base, but ammonia or organic amines are preferred because they volatilize and leave no inorganic ions in the coating film. The aqueous solvent may include a water-miscible organic solvent. As the polymerization initiator, ordinary ones can be used, such as organic peroxides such as benzoyl peroxide, t-butyl peroxide, and cumene hydroperoxide, azobiscyanovaleric acid, azobisisobutyronitrile, azobis-(2, 4-dimethyl)
Organic azo compounds such as valeronitrile, azobis-(2-amidinopropane) hydrochloride, inorganic water-soluble radical initiators such as potassium persulfate, ammonium persulfate, sodium persulfate, hydrogen peroxide, and these inorganic water-soluble radicals. Examples include redox initiators obtained by combining an initiator with sodium pyrosulfite, sodium bisulfite, divalent iron ions, etc., and these initiators may be used alone or in a mixture of two or more thereof. Such a polymerization initiator may be added to the reaction medium in advance, or may be added dropwise at the same time as the constituent monomers. The amount of these polymerization initiators to be used may be selected in the range of usually 0.05 to 5%, preferably 0.1 to 3% based on the total monomers. Further, if necessary, an appropriate amount of a conventional chain transfer agent (for example, mercaptans such as lauryl mercaptan and hexyl mercaptan) may be used in combination. A stably dispersed milk-like or cream-like emulsion resin is obtained by the emulsion polymerization method described above, and this resin has fine particles with an average particle size of about 0.02 to 0.5 μm. If water is removed from this emulsion by a suitable means such as spray drying, solvent displacement, azeotropy, centrifugation, overdrying, or freeze drying, somewhat agglomerated copolymer fine particles of up to about 40 μm in size can be obtained; No adhesion was observed, and it can be added to a high solids coating composition as insoluble polymer fine particles either as it is or after being crushed to some extent if desired. For drying the emulsion, spray drying is particularly preferred from the viewpoint of workability and particle size of the fine particles. Such means for separating and redispersing resin particles from an emulsion are well known and need not be described in detail; for example, in the solvent displacement method, water may be removed together with an azeotropic solvent such as xylene under reduced pressure, and in the solvent precipitation method, water may be removed together with an azeotropic solvent such as xylene. In this case, the resin particles can be precipitated and fractionated by adding a water-miscible polar solvent such as isopropanol, and fine powder particles can be obtained by ordinary freeze-drying methods. It can be used as the polymer fine particle (C) component by dispersing it in a solvent. The above copolymer fine particles used in the present invention can also be produced by the so-called NAD method in a non-aqueous organic medium using a resin having -|N-RY groups in the molecule as a dispersion stabilizer. .
As the non-aqueous organic medium, a low polar organic solvent which dissolves the monomer to be polymerized but does not dissolve the polymer, such as an aliphatic hydrocarbon such as hexane, heptane or octane, is usually used. within the molecule

[Formula] By appropriately selecting a resin having the group, the resin can be made soluble in the reaction medium, and due to its specific surface activity and electrochemical properties, it can serve as an effective dispersion stabilizer in the system. act. The initiator, reaction operation, post-treatment, etc. in the case of the NAD method are well known to those skilled in the art, and detailed description thereof will be omitted. Even when using the NAD method, the copolymer can be obtained as fine particles with an average particle size of about 1 to 40 μm. In this way, the fine particle polymer of the present invention can be produced not only by the emulsion polymerization method or the NAD method, but also by the presence of a resin having a specific amphoteric group as an emulsifier or dispersant. In the preparation of a high solids coating composition, this resin exhibits affinity for the volatile organic diluent of the coating composition, and therefore It also has the specific effect of contributing to stable dispersion of fine particles within the system. Therefore, in order to stably disperse the crosslinked fine particles in the coating composition, there is no need to perform any special modification treatment in advance. In this way, it is useful as an emulsifier and dispersant during the production of copolymers in aqueous and non-aqueous systems, and is also useful as a dispersion stabilizer for crosslinked copolymer fine particles in coating compositions that use relatively polar solvents. That is, within the molecule

The specificity of the present invention, which uses a resin having an amphoteric group called [Formula] group, is a surprising discovery that was completely unknown heretofore. Furthermore, by incorporating a crosslinking-reactive functional group such as a hydroxyl group or a carboxyl group into the resin part of this dispersion stabilizer, it can be used as a component for forming a three-dimensional film during coating film formation, thereby improving the physical properties of the film. can. Therefore, in addition to the advantages of conventionally known high solids coating compositions, the coating composition of the present invention can achieve further improvements in composition stability, coating performance, such as durability, and aesthetics. It is. The present invention will be explained below using reference examples, working examples, and comparative examples. In addition, "part" in the example sentence means "part by weight"
, and "%" means "% by weight". Reference Example 1 (a) Production of polyester resin having amphoteric groups: In a 2-Kolben equipped with a stirrer, nitrogen introduction tube, temperature control device, condenser, and decanter,
134 parts of bishydroxyethyl taurine, 130 parts of neopentyl glycol, 236 parts of azelaic acid,
Charge 186 parts of phthalic anhydride and 27 parts of xylene and raise the temperature. Water produced by the reaction is azeotroped with xylene and removed. The temperature is raised to 190°C over about 2 hours from the start of refluxing, stirring and dehydration are continued until the oxidation equivalent to carboxylic acid reaches 145, and then the mixture is cooled to 140°C. Next, while maintaining the temperature at 140° C., 314 parts of “Cardilla E10” (Versatellite glycidyl ester manufactured by Shell) was added dropwise over 30 minutes, and stirring was continued for 2 hours to complete the reaction. The resulting polyester resin has an acid value
59, hydroxyl number 90, _Mo 1054. (b) Production of polymer fine particles: 1 equipped with a stirrer, cooler, and temperature control device
282 parts of deionized water, 10 parts of the polyester resin obtained in (a) above, and 0.75 parts of dimethylethanolamine were placed in a reaction vessel, and the temperature was raised to 80°C while stirring.
While maintaining the temperature at °C, a solution prepared by dissolving 4.5 parts of azobiscyanovaleric acid in 45 parts of deionized water and 4.3 parts of dimethylethanolamine is added.
Next, 70.7 parts of methyl methacrylate, 94.2 parts of n-butyl acrylate, 70.7 parts of styrene, 2-
A mixed solution consisting of 30 parts of hydroxyethyl acrylate and 4.5 parts of ethylene glycol dimethacrylate is added dropwise over 60 minutes. After the dropwise addition, 1.5 parts of azobiscyanovaleric acid dissolved in 15 parts of deionized water and 1.4 parts of dimethylethanolamine was added, and stirring was continued at 80°C for 60 minutes, resulting in a nonvolatile content of 45%, pH of 7.2, and viscosity of 92 cps.
(25°C), an emulsion with a particle size of 0.156μ is obtained. This emulsion was spray-dried to obtain fine polymer particles. Reference Example 2 (a) Production of a modified epoxy resin having an amphoteric group: Using the same apparatus as in Reference Example 1, 73.5 parts of sodium salt of taurine, 100 parts of ethylene glycol,
Add 200 parts of ethylene glycol monomethyl ether and heat while stirring to bring the temperature to 120.
Raise to ℃. After the contents reached a uniform state of dissolution, a solution consisting of 470 parts of Epicote 1001 (manufactured by Ciel Chemical Co., diglycidyl ether type epoxy resin of bisphenol A, epoxy equivalent: 470) and 400 parts of ethylene glycol monomethyl ether was mixed for 2 hours. Drip with. After dropping, stirring and heating were continued for 20 hours to complete the reaction. The reaction product is purified and dried to obtain 518 parts of modified epoxy resin.
The acid value of this resin by KOH titration was 49.4, and the sulfur content by fluorescent X-ray analysis was 2.8%. (b) Production of polymer fine particles: Add 200 parts of deionized water and 0.2 parts of triethylamine to a stainless steel container, add 5 parts of the modified epoxy resin obtained in (a) above while stirring with a disper, and bring the temperature of the mixture to 70°C. After stirring for 10 minutes, a slightly cloudy aqueous solution was obtained. Next, this aqueous solution was charged into a reaction vessel similar to that used in Reference Example 1, and 106 parts of deionized water was added thereto and the temperature was maintained at 80° C. while stirring. To this was added a mixed aqueous solution consisting of 4.5 parts of azobiscyanovaleric acid, 4.9 parts of triethylamine, and 45 parts of deionized water, and while maintaining the temperature at 80°C, 150 parts of methyl methacrylate, 142 parts of n-butyl acrylate, 1.8 parts of glycidyl methacrylate, A mixed solution consisting of 1.2 parts of methacrylic acid was added dropwise over a period of 120 minutes. After dropping, at the same temperature, add 1.5 parts of azobiscyanovaleric acid, 1.6 parts of triethylamine,
Add a mixed aqueous solution consisting of 15 parts of deionized water and 15 parts of deionized water and continue stirring for 60 minutes to remove the non-volatile content of 45
%, pH 7.2, viscosity 69 cps (25°C), and particle size 0.172 μm. This emulsion was spray-dried to obtain fine polymer particles. Reference Example 3 Production of acrylic resin varnish: 710 parts of toluene and 200 parts of n-butanol were charged into a container equipped with a stirrer, a temperature control device, and a reflux condenser. Next, add 12 parts of methacrylic acid, 264 parts of styrene, 264 parts of methyl methacrylate, 360 parts of n-butyl acrylate, 100 parts of 2-hydroxyethyl acrylate, and 200 parts of the 10 parts of azobisisobutyronitrile having the following composition, and stir. While heating, the temperature was raised. The remainder of the above mixed solution while refluxing
810 parts were added dropwise over 2 hours, and then a solution consisting of 3 parts of azobisisobutyronitrile and 100 parts of toluene was added dropwise over 30 minutes. The reaction solution was further stirred and refluxed for 2 hours to increase the conversion rate to resin, and then the reaction was terminated to obtain an acrylic resin varnish with a non-volatile content of 50%. Reference Example 4 Production of alkyd resin varnish: Raw materials having the following composition were charged into a container equipped with a stirrer, a temperature controller, and a decanter, and heated while stirring. Dehydrated castor oil 260 parts Coconut oil 192 parts Trimethylolpropane 403 parts Diethylene glycol 65 parts Phthalic anhydride 578 parts Heating was continued until the temperature reached 100, and the reaction was completed. The resulting resin was diluted with xylene to a nonvolatile content of 70% to obtain an alkyd resin varnish. This varnish had a Gardner viscosity Z. Reference Example 5 Production of polyester resin varnish: The following raw materials were charged into a container equipped with a stirrer, a temperature control device, and a decanter, and heated while stirring. Ethylene glycol 39 parts Neopentyl glycol 130 parts Azelaic acid 236 parts Phthalic anhydride 186 parts did. Thereafter, the temperature was cooled to 140° C., 314 parts of Cardiura E-10 (epoxy resin, manufactured by Shell Co., Ltd.) was added, and stirring was continued for 2 hours to complete the reaction. The resulting resin had an acid value of 9, a hydroxyl value of 90, and a number average molecular weight of 1,050. This resin was diluted with xylene to a non-volatile content of 60% to obtain a polyester resin varnish having a Gardner viscosity of Y. Example 1 Materials having the following composition were weighed into a stainless steel container and stirred using a laboratory stirrer to prepare a coating composition.

[Table] Resin When this material was diluted with a solvent of xylene/ethylene glycol monobutyl ether = 1/1 and adjusted to a viscosity of 25 seconds using a food cup No. 4, the non-volatile content of the composition of this example was 39.6%. The nonvolatile content of the Atsuta Comparative Example 1 was 37.6%. Furthermore, the coating of this example had much better sagging during spray coating than that of Comparative Example 1. Example 2 A coating composition having the following composition was prepared using the same method as in Example 1.

[Table] Composition Each composition was diluted with a solvent of xylene/ethylene glycol monobutyl ether = 1/1, and adjusted to a viscosity of 20 seconds using a food cup No. 4. The coating of this example was much better than that of Comparative Example 2 in terms of pin-sagging performance and metal retention when applied using a normal spray gun. Example 3 100 parts of the alkyd resin varnish of Reference Example 4 and 100 parts of the rutile-type titanium oxide pigment were weighed into a dispersion container, and
A white paste was prepared by mixing and dispersing using a paint conditioner. Using this paste,
A coating composition with the following formulation was prepared.

[Table] Melamine
p-Toluenesulfonic acid 0.1 part 0.1 part Each composition was diluted with a solvent of xylene/ethylene glycol monobutyl ether = 1/1, and adjusted to a viscosity of 25 seconds using a food cup No. 4. Conventional spray painting (same speed, same interval)
After that, when baking was performed at 140°C for 30 minutes, a coating film with a thickness of 48μ was obtained in this example, whereas a coating film with a thickness of 34μ was obtained in Comparative Example 3. . Example 4 100 parts of the polyester resin varnish of Reference Example 5 and 90 parts of the rutile-type titanium oxide pigment were weighed into a dispersion container, and mixed and dispersed using a paint conditioner to prepare a white paste. Using this paste, put the following ingredients into a stainless steel container.

[Table] Trimerized product of Nato A white coating composition was prepared by stirring and mixing at room temperature for 30 minutes using a laboratory stirrer. Each composition was diluted with xylene/butyl acetate=1/1 thinner and adjusted to a viscosity of 25 seconds using a No. 4 food cup. After spray painting using a conventional method, a coating film was obtained by drying at 80°C for 30 minutes. The coatings of this example were far superior to those of the comparative example in terms of pin-sagging properties and coating thickness during coating. Reference Example 6 Production of polymer fine particles: 297 parts of deionized water, 40 parts of the polyester resin obtained in (a) of Reference Example 1, and dimethylethanolamine in one reaction vessel equipped with a stirrer, a cooler, and a temperature control device. Add 3.0 parts of azobiscyanovaleric acid and dissolve while stirring while maintaining the temperature at 80℃.
Add 1.5 parts dissolved in 50 parts deionized water and 1.5 parts dimethylethanolamine. Next, a mixed solution consisting of 160 parts of styrene and 40 parts of ethylene glycol dimethacrylate is added dropwise over a period of 60 minutes. After dropping, add 0.5 azobiscyanovaleric acid.
1 part deionized water and 10 parts dimethylethanolamine
Add 0.5 part of the solution and stir at 80°C for 60 minutes to obtain an emulsion with nonvolatile content of 38%, pH of 7.2, and particle size of 0.04μ. This emulsion was charged into a container equipped with a second decanter, and dehydrated by azeotroping with xylene under reduced pressure, and the dispersion medium was replaced with xylene to obtain a dispersion solution with a nonvolatile content of 20%. Reference Example 7 Production of polymer fine particles: In a reaction vessel similar to that used in Reference Example 1, 40 parts of the modified epoxy resin obtained in (a) of Reference Example 2, 5 parts of dimethylethanolamine, and 297 parts of deionized water were added. The temperature was maintained at 80°C while stirring to ensure uniform dissolution. To this, 1.5 parts of azobiscyanovaleric acid,
A mixed aqueous solution consisting of 1.5 parts of dimethylethanolamine and 50 parts of deionized water was added, and a mixed solution of 180 parts of methyl methacrylate and 20 parts of ethylene glycol dimethacrylate was added dropwise over 120 minutes while maintaining the temperature at 80°C. After the dropwise addition, a mixed aqueous solution consisting of 0.5 parts of azobiscyanovaleric acid, 0.5 parts of dimethylethanolamine, and 10 parts of deionized water was added at the same temperature, and stirring was continued for 60 minutes to obtain a nonvolatile content of 38%, pH of 7.2, and particle size. An emulsion of 0.03μ was obtained. After adding 350 parts of isopropyl alcohol to this emulsion and filtering out the resulting precipitate,
It was redispersed in butyl acetate to obtain a dispersion solution with a nonvolatile content of 25%. Example 5 A coating composition having the following composition was prepared in the same manner as in Example 1.

[Table] Resin This material was diluted with a solvent of xylene/ethylene glycol monobutyl ether = 1/1, adjusted to a viscosity of 25 seconds with a food cup No. 4, and the dry film thickness was
It was painted to have a thickness of 25μ. The coatings of this example had much better sagging during spray coating than those of the comparative examples, and the appearance of the coating film was also good. Example 6 A coating composition having the following composition was prepared in the same manner as in Example 1.

[Table] *As described in Example 2, each composition was diluted with a 1/1 xylene/ethylene glycol monobutyl ether solvent and adjusted to a viscosity of 20 seconds using a food cup No. 4. When applied using an ordinary spray gun, the pin/sag performance and metal retention of this example were far better than those of Comparative Example 6, and the appearance of the paint film was also good.

Claims (1)

[Scope of Claims] 1. A film-forming polymer (A) having a functional group capable of reacting with a crosslinking agent, a volatile organic liquid diluent (B) supporting the polymer, and a combination of the polymer and the diluent. Polymer fine particles (C) that are insoluble and stably dispersed in the combination;
and a crosslinking agent (D) dissolved in the diluent, and the polymer fine particles (C) have a formula [Formula] in the molecule (wherein R may have a substituent C ₁ ~ _C6 alkylene or phenylene group, Y is -
Obtained by copolymerizing two or more monomers having α,β-ethylenically unsaturated groups in an aqueous or organic medium in the presence of a resin having a group represented by COOH or -SO ₃ H) A coating composition characterized by comprising crosslinked copolymer fine particles. 2 Polymer components are film-forming polymers by weight ratio
It consists of 50 to 99.5 parts of (A) and 50 to 0.5 parts of crosslinked copolymer fine particles (C), and the crosslinking agent (D) is 5 to 100 parts per 100 parts of polymer components (A) + (C). Liquid diluent (B) is 10 to 100 parts of total amount of polymer component and crosslinking agent (A) + (C) + (D)
A composition according to claim 1 in a weight proportion of 2000 parts. 3. The composition according to claim 1, wherein the film-forming polymer having a functional group capable of reacting with a crosslinking agent is an acrylic resin or an alkyd resin having a hydroxyl group or a carboxyl group. 4 The volatile organic liquid diluent is an aliphatic hydrocarbon,
The composition according to claim 1, which is an aromatic hydrocarbon, an ester, a ketone, an alcohol, or a mixture thereof. 5. The composition according to claim 1, wherein the crosslinking agent is an aminoplast resin or a polyvalent isocyanate compound. 6 Polymer fine particles have a formula [formula] group in the molecule (where R is a C ₁ to _{C 6} alkylene or phenylene group that may have a substituent, Y is -COOH
or -SO ₃ H), in an aqueous or organic medium, by copolymerizing two or more monomers having α,β-ethylenically unsaturated groups, and A monomer that has two or more radically polymerizable ethylenically unsaturated groups in its molecule as part of its body, or a monomer that has two types of ethylenically unsaturated groups that each carry a group that can react with each other. 2. The composition according to claim 1, which is crosslinked copolymer fine particles having an average particle diameter of 0.02 to 40 μm, which are crosslinked by the presence of a copolymer. 7. The composition according to claim 1, which contains a metal or non-metal pigment.