JPH0530867B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a water-based paint composition useful as a top coat, and more particularly to a water-based paint composition that contains a water-based resin and water-insoluble resin fine particles as film-forming components and has particularly improved workability and film performance. It is. Attempts to use a combination of an aqueous resin and a water-insoluble resin powder as a resin vehicle for an aqueous coating composition have attracted attention in recent years. For example, patent application No. 51-31636
No. 51-25224 etc., 0.5 of the resin particles are added to a slurry consisting of 10 to 70 wt parts of resin particles and 90 to 30 wt parts of water.
It is also reported in Japanese Patent Application No. 49-127151 that ~30wt% of water-dilutable resin is added to the composition for storage stability.
% of water-soluble or water-dispersible resin is added. However, with such slurry-type paints, it is generally difficult to increase the concentration of non-volatile matter, making it impossible to apply thickly, and the adhesion of the paint film after painting is insufficient, which tends to cause cracks, and the workability, storage stability, etc. It has not been put into practical use due to issues such as coating film performance. Also, patent application No. 54-74606,
No. 54-170262, Japanese Patent Publication No. 55-4149, etc. are water-dispersible coating compositions containing powder coatings and water-soluble resins as main components, with water-soluble resins being blended at approximately 10 to 20% of the powder resin. things are listed. However, when these are dispersed in water, they become a water-powder resin slurry, and the water-soluble resin is expected to play the role of a dispersion stabilizer. In the end, it is no different from a slurry-type paint, and it does not essentially improve its inherent drawbacks. Under these circumstances, the present applicant has developed a remarkable water-based paint composition containing a resin vehicle that is a combination of a water-soluble or water-dispersible resin and water-insoluble resin particles, and has filed a patent application (Japanese Patent Application No. 1983). −114686
No.) was done. The invention according to the application is based on 100ml of 5g of water-based varnish with a viscosity range commonly used for paints.
Water tolerance and water-based varnish with a solid content of 1% w/w are weighed into a beaker, diluted with deionized water, and expressed as the water dilution ratio at which No. 1 type (26 point type) becomes unreadable when passed through the beaker. The surface tension of the solution obtained by diluting with deionized water is used as the selection parameter for water-based resin (water-soluble resin or water-dispersible resin, the same applies hereinafter), and the water tolerance is 4 or more and the surface tension is 51 dyne/cm or less. If at least one type of water-based resin that meets the requirements is used, the solid content weight ratio of the water-based resin and water-insoluble resin fine powder is 98:2 to 2.
Even if it is contained in a wide range of mixing ratios such as 45:55, no increase in the viscosity of the system is observed, and therefore the resin content of water-based paints can be increased, which not only improves workability but also has excellent stability. It was intended to provide a coating composition with excellent coating film performance. However, the water-based paint composition in the above application was developed as an intermediate coat or undercoat, just like the various proposals made in the past, and is particularly suitable for use as a topcoat that requires a high gloss and flat coated surface. The performance was not satisfactory. However, water-based paint compositions not only have excellent paint performance such as workability and storage stability, but also have excellent coating performance such as durability, gloss, and smoothness, and are useful as top coats. There is an urgent need for this in various painting fields including the automobile industry. The applicant previously proposed that the average particle diameter of 0.3 to 6μ and the maximum particle diameter of 10μ or less obtained by polymerizing an aqueous resin selected from alkyd resins and polyester resins and an unsaturated compound having a polymerizable carbon-carbon double bond. A water-based coating composition containing resin particles in a solid content weight ratio of 99:1 to 40:60; An aqueous coating composition containing resin particles with an average particle diameter of 0.01 to 0.1μ obtained by polymerization of a saturated compound in a solid content weight ratio of 99:1 to 15:85, and a vinyl-modified alkyd resin and a vinyl-modified polyester resin. Average particle size obtained by polymerizing an aqueous resin selected from and an unsaturated compound having a polymerizable carbon-carbon double bond.
Fine resin particles of 0.01 to 6 μ in solid weight ratio of 99:1 to
The water-based paint composition containing the ratio of 15:85 improves workability,
It was discovered that it not only has excellent storage stability and durability, but also provides a high gloss and smooth painted surface, making it useful as a top coat.
No. 57-174891 and No. 57-174892. The present invention is a further development of the above invention. In other words, the above invention is a combination of a specific water-based resin and a specific water-insoluble resin, and when the resin particles have an average particle size within a specific range and are used in a certain blending ratio, the system has a special rheology. Due to its characteristics, it is possible to increase the resin concentration without increasing viscosity, and there is a water-based paint composition that has excellent workability, provides a high gloss and smooth painted surface, and fully satisfies various requirements as a top coat. However, the present inventors have conducted research on the particle structure and surface structure of the resin particles, and have made the particles into at least one kind of polymerizable carbon-carbon dioxide. An unsaturated monomer having a double bond is polymerized by a two-stage polymerization method in water in the presence of a seed emulsion to form a two-layer structure of an inner shell and an outer shell,
By making the inner shell relatively hard compared to the outer shell, the flow characteristics of the paint are changed, and workability and coating film performance against pinholes are significantly improved. We realized that a wider range of combinations could be used and completed the present invention. Therefore, the object of the present invention is to provide a water-based paint composition that has excellent workability, storage stability, and durability, and can provide a high-gloss, flat coated surface, which is particularly effective in terms of workability and paint film performance such as pinholes. An object of the present invention is to provide a coating composition that can provide excellent effects. The object of the present invention is to provide an aqueous coating composition that contains a binder component consisting of an aqueous resin and water-insoluble resin particles as an essential component, and optionally contains pigments, crosslinking agents, and other coating additives.
The water-based resin is at least one selected from the group consisting of polyester resin, alkyd resin, vinyl resin, vinyl-modified polyester resin, and vinyl-modified alkyd resin, and the water-insoluble resin fine particles are at least one polymerizable carbon-carbon double In the presence of an emulsion seeding unsaturated monomers with bonds,
Polymerization is carried out in water using a two-stage polymerization method, and the unsaturated monomer composition in each stage is controlled to produce a hard inner shell with a relatively high glass transition temperature in the first stage, and a relatively hard inner shell with a relatively high glass transition temperature in the second stage. Fine particles with an average particle diameter of 0.3 to 6μ having a core-shell double structure obtained by forming a soft outer shell with a low glass transition temperature, and the solid content weight ratio of the water-based resin and water-insoluble resin is 99:1. This is achieved by a water-based paint composition characterized by a ratio of 15:85 to 15:85. The water-based resin (water-soluble resin or water-dispersible resin, hereinafter the same) used in the present invention is a polyester, alkyd, vinyl, vinyl-modified polyester or vinyl-modified alkyd resin commonly used in the coating field. That is, the polyester resin used in the present invention is a general polyester resin obtained by a polycondensation reaction of a polybasic acid and a polyhydric alcohol, and in this case, the polybasic acids include oxalic acid, succinic acid, succinic anhydride, adipic acid, Linear dibasic acids such as azelaic acid and sebacic acid; phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, tetrahydrophthalic anhydride, hexahydrophthalic acid, hexahydrophthalic anhydride, tetrabromophthalic anhydride, trimellitic anhydride, Aromatic fatty acids such as trimellitic acid, pyromellitic acid, and pyromellitic anhydride; unsaturated dibasic acids such as maleic acid, maleic anhydride, fumaric acid, and itaconic acid; and polyhydric alcohols such as ethylene glycol, propylene glycol, Glycols such as 1,3-butylene diol, 1,6-hexane diol, diethylene glycol, neopentyl glycol, triethylene glycol, hydrogenated bisphenol A, bisphenol dihydroxypropyl ether, glycerin, trimethylolethane, trimethylolpropane, Pentaerythritol and the like are used as appropriate. However, the above-mentioned polybasic acids and polyhydric alcohols are not limited in any way, and may be any one that can be used as a raw material for ordinary polyester resins. It is also possible to use Alkyd resin uses the above polyester as a drying oil,
It is esterified and modified with fatty acids, etc., and the oil and fat components include linseed oil, tung oil, oiticica oil,
Any known ones such as dehydrated castor oil, coconut oil, hydrogenated coconut oil, rice sugar fatty acids, tall oil fatty acids, soybean oil, octylic acid, etc. can be used, and the alkyd resins can be epoxy-modified, rosin-modified, or phenolic resin-modified ones. It doesn't matter if it is. The methods for producing these resins are well known to those skilled in the art and need not be detailed. Vinyl resins are also preferably used in the present invention. This vinyl resin is obtained by polymerizing monomers or any combination of the following monomers having one or more polymerizable carbon-carbon double bonds in the molecule. 1) Carboxyl group-containing monomers such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, etc. 2) Hydroxyl group-containing monomers such as 2-hydroxyethyl acrylate,
Hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, allyl alcohol, methalyl alcohol, etc. 3) Nitrogen-containing alkyl acrylate or methacrylate For example, dimethylaminoethyl acrylate,
Dimethylaminoethyl methacrylate, etc.4) Polymerizable amides, such as acrylamide, methacrylic acidamide, etc.5) Polymerizable nitriles, such as acrylonitrile, methacrylonitrile, etc.6) Alkyl acrylates or methacrylates, such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-butyl acrylate, n-butyl methacrylate, 2-ethylhexyl acrylate, etc. 7) Polymerizable aromatic compounds such as styrene, α-methylstyrene, vinyltoluene, t-butylstyrene, etc. 8) α-olefins such as ethylene, propylene, etc. 9) Vinyl compounds such as vinyl acetate, vinyl propionate, etc. 10) Diene compounds such as butadiene, isoprene, etc. These unsaturated monomers with polymerizable carbon-carbon double bonds can be treated with light, heat, organic peroxide or inorganic peroxide. Polymerization can be carried out by any known polymerization method in the presence of a radical initiator such as an azo compound or an azo compound. Yet another group of aqueous resins that are preferably used in the present invention include vinyl-modified polyester or alkyd resins, i.e., resins in which vinyl polymer segments are incorporated into polyester resins or alkyd resins. can be given. Such vinyl-modified resins can be obtained, for example, by the following methods. (1) Vinyl resin is synthesized in the presence of polyester or alkyd resin having unsaturated groups. When producing polyester by polycondensation reaction of polybasic acid and polyhydric alcohol, unsaturated acids such as maleic acid, maleic anhydride, fumaric acid, citraconic acid, itaconic acid,
By using dimer acid etc., polyesters having unsaturated groups can be obtained, and such unsaturated polyesters or saturated polyesters can be treated with drying oil, drying oil, etc.
When esterified and modified by the action of a fatty acid or the like, an alkyd resin having an unsaturated group can be obtained. In the presence of polyester or alkyd resins containing such unsaturated groups, common free radical catalysts such as azobisisobutyronitrile, benzoyl peroxide, di-t-butyl peroxide, cumene hydroperoxide, etc. are used as initiators. Alternatively, the vinyl-modified polyester or alkyd resin used in the present invention can be obtained by polymerizing a vinyl monomer using a chain transfer agent such as ethyl mercaptan, butyl mercaptan, dodecyl mercaptan, carbon tetrabromide, carbon tetrachloride, etc. . As the vinyl monomer in this case, the aforementioned various compounds having one or more polymerizable carbon-carbon double bond unsaturated bonds in the molecule, which are usually used in the production of vinyl resins, are used. . (2) Polymerization of a vinyl monomer group containing an unsaturated monomer having a polymerizable carbon-carbon double bond containing an oxirane group in the presence of a polyester or alkyd resin containing a carboxylic acid group. Do this. Polyester resins or alkyd resins usually contain carboxylic acid groups due to the polybasic nature of the raw materials from which they are manufactured. Therefore, glycidyl acrylate,
The above-mentioned vinyl monomer group containing as one component an unsaturated monomer having a polymerizable carbon-carbon double bond having an oxirane group such as glycidyl methacrylate is added to the carboxylic acid group-containing polyester or alkyd resin. When polymerized in the presence of these compounds, vinyl-modified polyester or alkyd resins are obtained. (3) Polymerization of a vinyl monomer group containing a monomer containing a carboxylic acid group as one component is carried out in the presence of a polyester or alkyd resin containing an oxirane group. When producing a polyester or alkyd resin, for example, a polyester or alkyd resin having an oxirane group is obtained by using a polyhydric alcohol component having two or more oxirane groups and a polybasic acid component. unsaturated monomers with polymerizable carbon-carbon double bonds, such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid,
The vinyl-modified polyester or alkyd resin used in the present invention can be obtained by reacting the aforementioned vinyl monomer group containing maleic acid, fumaric acid, etc. as one component. (4) A method of reacting a polyester or alkyd resin (or vinyl resin) containing a carboxylic acid group with a vinyl resin (or polyester or alkyd resin) containing an oxirane group. If a polyester or alkyd resin and a vinyl resin are supported with a carboxylic acid group on one side and an oxirane group on the other, and both resins are reacted, a vinyl-modified polyester or alkyd resin can be obtained by the reaction of the carboxylic acid group and the oxirane group. . (5) A vinyl monomer is polymerized in the presence of a mercapto group-containing polyester or alkyd resin. A polyester or alkyd resin is obtained using a polybasic acid or a polyhydric alcohol having a mercapto group, and this is used in a chain transfer reaction to polymerize the above-mentioned vinyl monomer. The above is a typical production example of the vinyl-modified polyester or alkyd resin of the present invention, but it is not intended to limit the present invention. It should be understood that any available method can be used and any of them are suitable for the purposes of the present invention. In order to make the resin water-soluble, for example, an acidic group such as a carboxyl group is replaced with a basic substance (for example, monomethylamine, dimethylamine, trimethylamine, monoethylamine, triethylamine, monoisopropylamine, diisopropylamine, diethylenetriamine, triethylene Neutralize with tetramine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, dimethylethanolamine, morpholine, methylmorpholine, piperazine, ammonia, sodium hydroxide, potassium hydroxide, lithium hydroxide, etc. The water-based resin is imparted with water-solubility or water-dispersibility and is conveniently used for the purpose of the present invention.
One species or two or more species may be selected as appropriate, and they may be thermoplastic or thermosetting. That is, these may or may not carry functional groups that can react with other aqueous resins and/or powder resin functional groups upon heating. Examples of such functional groups to be supported include carboxylic acid groups, sulfonic acid groups, phosphoric acid groups, hydroxyl groups, oxirane groups, active methylol groups, amino groups, reactive carbon-carbon unsaturated bonds, isocyanate groups, and blocked isocyanate groups. Examples include nato groups and halogens, and these can be easily incorporated into the resin, if desired, by common methods such as selecting monomers during resin production and controlling polymerization reactions. In the present invention, a water-insoluble resin fine powder is used together with the above water-based resin, and this water-insoluble resin fine powder is a vinyl polymer obtained by polymerizing an unsaturated compound having a polymerizable carbon-carbon double bond. Alternatively, it is a copolymer. In this case, the unsaturated compound having a carbon-carbon double bond is the same as described above regarding the vinyl aqueous resin, and is a compound having one or more polymerizable carbon-carbon double bonds in the molecule. They can be arbitrary and used alone or in combination. However, one of the most important features of the present invention is that the fine particles of the acrylic or vinyl polymer or copolymer are water-insoluble and are made as fine particles. An unsaturated monomer having a type of polymerizable carbon-carbon double bond is polymerized in two stages in water in the presence of a seed emulsion, and the composition of the unsaturated monomer in each stage is controlled to produce the first stage. A hard inner shell with a relatively high glass transition temperature is formed in the second stage, and a soft outer shell with a relatively low glass transition temperature is formed in the second stage.The average particle size is 0.3 to 0.3 and has a core-shell double structure. It needs to be 6μ vinyl resin particles. In this way, water-insoluble resin particles made of a polymer of an unsaturated compound having a polymerizable carbon-carbon double bond are combined with a hard inner shell made of a polymer having a relatively high glass transition temperature and a relatively low polymer. By creating a double structure with a soft outer shell consisting of a combination of water-based resin and water-insoluble resin particles, it exhibits unique fluidity characteristics and is particularly excellent in terms of workability, making it possible to prevent pinholes, etc. A top coating composition with improved performance and a high gloss and smooth coating surface is obtained, and the type of water-based resin to be combined with the polymer fine particles and the permissible particle size range of the resin fine particles are expanded ( However, as will be described later, the average particle diameter of the fine particles is limited to a certain range for reasons of fine particle production, and the present invention was made based on this knowledge. When producing a polymer of an unsaturated compound having a polymerizable carbon-carbon double bond, for example, the glass transition temperature (Tg) of the homopolymer obtained differs depending on the type of monomer to be polymerized, and the glass transition temperature (Tg) of the copolymer varies. case,
that its glass transition temperature is the intermediate glass transition temperature of the homopolymer of each monomer used;
The ability to arbitrarily design the glass transition temperature of a copolymer by changing the ratio of monomers, and the ability to lower the glass transition temperature of a polymer by blending plasticizers, solvents, etc., all belong to known technology. . Furthermore, methods for producing polymers of unsaturated compounds having polymerizable carbon-carbon double bonds and techniques for producing fine particles of the polymers are also known. Therefore, it is relatively easy to form the water-insoluble resin fine particles of the present invention into a double structure consisting of a hard inner shell made of a polymer with a relatively high glass transition temperature and a soft outer shell made of a polymer with a relatively low glass transition temperature. This can be easily done by a person skilled in the art according to the law. However, from the perspective of adjusting these particles to fine particles,
It is particularly recommended that the polymers for both the inner shell and the outer shell be produced by emulsion polymerization. This emulsion polymerization must be carried out in the presence of a seed emulsion. In polymerization in the presence of a normal emulsifier, particles with different compositions are often present in the first and second stages of polymerization. Do not fit. In addition, the content of emulsifier is high, and especially when it is formed into a coating film, there is a decrease in water resistance. On the other hand, in the presence of a seed emulsion, the water-insoluble resin particles that are the object of the present invention are obtained by being sequentially absorbed by the seed emulsion that is present in the first stage and second stage. The seed emulsion used here may be a general emulsion, but a particularly suitable one is one in which an initiator and an unsaturated monomer having a carbon-carbon double bond are prepared in water at a temperature of 60°C to 90°C. It is an emulsion obtained by polymerizing to generate a water-soluble oligomer, and then additionally polymerizing an unsaturated monomer having at least one carbon-carbon double bond using this as a core. Polymerization initiators are also common, 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, and hydrogen peroxide; redox-based initiators can be used. The first and second stage polymerizations are carried out in the presence of the seed emulsion thus obtained.
Incidentally, the resin particle size is preferably controlled to be 0.3 to 6 μm or less. The monomer(s) that should give the polymer a glass transition temperature lower than that of the outer shell are then added, along with additional initiator if desired, to seed the polymer particles constituting the inner shell. It is then polymerized by emulsion polymerization to obtain double-structured fine particles with a particle size of 0.3 to 6μ. As already mentioned, the carbon-carbon polymer has a double structure of a hard inner shell made of a polymer with a relatively high glass transition temperature and a soft outer shell made of a polymer with a relatively low glass transition temperature. When fine particles of a polymer of an unsaturated compound having a double bond are used, the types of aqueous resins to be combined with the fine particles and the permissible particle size range of the fine resin particles can be expanded to a wide range. However, taking into account that the resin fine particles are produced by a two-stage polymerization method as described above, it is most practical for the average particle diameter of the fine particles to be in the range of 0.3 to 6 μm. A particularly preferred range is 0.4 to 5μ. In the present invention, the weight ratio of the unsaturated compound having a carbon-carbon double bond in the polymer constituting the inner shell and outer shell of the double-structure fine particles can also be varied over a wide range. , is usually arbitrarily selected within the range of 3 to 60% by weight of the outer shell/97 to 40% by weight of the inner shell. The number average molecular weight of the polymer that makes up the outer shell is usually 2,500 to 50,000.
It is preferable that However, these are not absolute and can be changed as appropriate depending on desired effects and other factors. The resin fine particles having the above-mentioned specific structure and specified particle size can be used alone or in combination of two or more types, and they may react mutually with the water-based resin or between the resin fine particles upon heating. It is also free to carry a functional group that can be used or not to carry such a functional group.
After all, the resin composition used in the present invention may be thermoplastic or thermosetting as a whole. In the coating composition of the present invention, the solid content of the water-based resin and the water-insoluble resin fine particles is 99 to 15% for the former and 1 to 85% for the latter, preferably 98 to 40% for the former and 2 for the latter. It is necessary to combine within the range of ~60%. This is because if the water-based resin content is too small, the dispersion stability of the resin particles will deteriorate and the smoothness of the coating film will be impaired.
This is because if the amount is less than % by weight, the purpose of the present invention as a top coat cannot be achieved. Water is used as the medium, but a hydrophilic polar organic solvent can also be co-present if desired. Examples of such organic solvents include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, methanol, ethanol, isopropyl alcohol, n-butanol, sec-butanol, t-butanol, and dimethylformamide. However, in the composition of the present invention, the ratio of the water medium to the resin component is quite fluid. This means that the solid content is usually around 10-80% for spray painting, and around 5-90% for brush painting.
For immersion, approximately 1 to 60% of water is used, but the composition of the present invention is extremely stable due to its unique fluidity characteristics and the unique surface characteristics of the resin particles, and is resistant to any moisture content. This is because the content can be adjusted and stored, and it can be diluted with water to a predetermined concentration before use. In the present invention, the above-mentioned water-based resin, water-insoluble resin fine particles with unique surface characteristics and a double structure, and water are essential ingredients, and by using such a composition as it is as a clear paint, high gloss can be achieved. It is possible to obtain a smooth topcoat surface that is particularly excellent in terms of coating performance against pinholes and the like. In addition, by adding pigments, cross-linking agents, and other additives to this resin composition and uniformly dispersing and mixing it according to ordinary paint manufacturing techniques, it has excellent workability, has high gloss, smoothness, and is especially free from pinholes. A water-based top coating composition with excellent coating performance can be obtained. As the pigment, any pigment commonly used in top coatings can be used and can be well dispersed. When blending pigments, make a pigment paste in advance using a portion of the water-based resin, add the remaining amount of the water-based resin, resin fine particles, and other additives, and use a known dispersion machine such as a gate mixer or high-speed disper. It is particularly preferable to mix and disperse them uniformly.
However, of course, it is also possible to form a paint by mixing and dispersing each component using a dispersion machine from the beginning. A crosslinking agent may also be added to the coating composition of the present invention, if desired, such as melamine-formaldehyde resin, methoxy-modified, butoxy-modified melamine-formaldehyde resin, urea resin, thiourea resin, guanamine resin, acetoguanamine resin, etc. Any known crosslinking agent such as aminoplast, isocyanate, isocyanate, polyisocyanate, isocyanate compounds such as blocked isocyanate, and phenolic resin is preferably used. Furthermore, if desired, other conventional additives such as anti-sagging agents, anti-settling agents, anti-color separation agents, anti-cissing agents, surface tension regulators, antioxidants, light stabilizers, ultraviolet absorbers, etc. may be added as appropriate. is also possible. These pigments,
The amount of the crosslinking agent and other additives used, the blending method, etc. are all appropriately selected and used in accordance with the production of ordinary topcoat paints. The coating composition of the present invention can be applied as it is or further diluted with water, applied by conventional coating methods such as spraying, dipping, brushing, etc., and then dried or baked by heating, and is highly glossy, smooth, and highly durable. A topcoat surface with excellent coating performance against pinholes etc. can be obtained. Furthermore, the paint has good storage stability and is exceptionally easy to work with, making it extremely useful as a water-based paint composition for top coating. The present invention will be explained below with reference to production examples, examples, and comparative examples. Note that unless otherwise specified, "parts" means "parts by weight." Production Example 1 Production of Resin Fine Particles-1 1100 parts of deionized water is weighed out into a 2 liter glass reaction vessel equipped with a stirrer, a temperature controller, and a cooling tube, and the temperature is brought to 80°C. 5 parts of an aqueous solution consisting of 100 parts of deionized water and 6 parts of ammonium persulfate, and a monomer mixture consisting of 210 parts of methyl methacrylate, 75 parts of 2-ethylhexyl acrylate, and 15 parts of n-dodecyl mercaptan were added to this water with stirring. part and continue stirring for 5 minutes. Thereafter, 295 parts of the monomer mixture was added dropwise into the reaction solution over 1 hour. After continuing to stir for 15 minutes after the dropwise addition,
An aqueous solution consisting of 10 parts of deionized water and 1 part of ammonium persulfate is added and stirring is continued for 1 hour to complete the reaction, yielding a seed emulsion with a non-volatile content of 20%. In a reaction vessel similar to that used for seed emulsion synthesis, add 250 parts deionized water and seed emulsion.
Weigh out 25 parts and bring the temperature to 80℃. Add 10 parts of deionized water and ammonium persulfate to this reaction vessel under stirring.
0.1 part of an aqueous solution was added, followed by a pre-emulsion of 400 parts of methyl methacrylate, 29 parts of 2-hydroxyethyl acrylate, 200 parts of deionized water, 0.4 parts of sodium dedocylbenzenesulfonate, and 0.9 parts of ammonium persulfate for 2 hours. Sprinkle and drip. The calculated Tg of a random polymer with this monomer composition is 93.5°C. 1 hour and 30 minutes after the start of dropping the pre-emulsion, 60 parts of 2-ethylhexyl acrylate and 2-
A monomer mixture consisting of 6 parts of hydroxyethyl acrylate was added dropwise over 30 minutes at the same time as the pre-emulsion. The calculated Tg of a random polymer consisting of this monomer composition is -80°C. 30 minutes after completion of dripping
After continuing to stir for 1 minute, an aqueous solution consisting of 20 parts deionized water and 0.2 parts ammonium persulfate is added.
Stirring was continued for a further 1 hour to complete the reaction. The obtained emulsion had a nonvolatile content of 50.0%, and the average particle size of the fine resin particles contained therein was 1.6μ and the maximum particle size was 4.5μ. Note that the particle size was measured using a transmission electron microscope. Calculation of Tg is also available in "Introduction to Synthetic Resins for Paints" by Kyozo Kitaoka, Kobunshi Publishing Co., Ltd., 168-170.
I followed the page. Production Example 2 Production of Resin Fine Particles-2 In a reaction vessel similar to that used in Production Example 1, 245 parts of deionized water and 25 parts of the seed emulsion of Production Example 1 were weighed out, and the temperature was brought to 80°C. Into this reaction vessel, under stirring, add 20 parts of deionized water and 0.1 part of ammonium persulfate.
195 parts of methyl methacrylate, 100 parts of 2-ethylhexyl acrylate, 200 parts of deionized water, 0.3 parts of sodium dodecylbenzenesulfonate, and ammonium persulfate.
A pre-emulsion of 0.6 parts is added dropwise over a period of 2 hours. The calculated Tg of a random polymer with this monomer composition is 8.5°C. After stirring was continued for 10 minutes after the completion of the dropwise addition (after the inner shell was formed), a monomer mixture consisting of 65 parts of methyl methacrylate and 135 parts of 2-ethylhexyl acrylate was added dropwise over a period of 15 minutes. The calculated Tg of a random polymer consisting of this monomer composition is -48°C. 30 minutes after completion of dripping
After stirring for a few minutes, an aqueous solution consisting of 20 parts of deionized water and 0.2 parts of ammonium persulfate was added.
Stirring was continued for a further 1 hour to complete the reaction. The obtained emulsion has a non-volatile content of 48.0%, and the average particle size of the fine resin particles contained is 2.6μ, and the maximum particle size is
It was 4.5μ. Production Example 3 Production of Resin Fine Particles-3 520 parts of deionized water was weighed into a reaction vessel similar to that used in Production Example 1, and the temperature was brought to 80°C. An aqueous solution consisting of 100 parts of deionized water, 15 parts of ammonium persulfate, and a monomer mixture consisting of 384 parts of methyl methacrylate, 96 parts of 2-ethylhexyl acrylate, and 40 parts of n-dodecyl mercaptan were added to this water with stirring. Add 20 parts and continue stirring for 5 minutes. At this stage a seed emulsion has been obtained. After that, the monomer mixture was added for 1 hour.
Add 500 parts dropwise into the reaction solution. The calculated Tg of a random polymer with this monomer composition is 41.5℃
It is. After continuing stirring for 15 minutes after the completion of the addition, a monomer mixture consisting of 48 parts of methyl methacrylate, 58 parts of 2-ethylhexyl acrylate, 2 parts of methacrylic acid, and 12 parts of 2-hydroxyethyl acrylate was added dropwise over 20 minutes. The calculated Tg of a random polymer with this monomer composition is -26.5°C. Subsequently, an aqueous solution consisting of 40 parts of deionized water and 0.2 parts of ammonium persulfate is added, and stirring is continued for 1 hour to complete the reaction. The nonvolatile content of the obtained emulsion was 50.0%, and the average particle size of the fine resin particles contained therein was 0.40μ and the maximum particle size was 1.2μ. Reference example Production of resin fine particles for comparison In a reaction vessel similar to that used in the production of resin fine particles-1, 900 parts of deionized water and Metrose 60SH-50 were added.
(Manufactured by Shin-Etsu Chemical Co., Ltd., methyl cellulose) 1.5 parts, methyl methacrylate 210 parts, 2-ethylhexyl acrylate 63 parts, 2-hydroxyethyl acrylate 21 parts, methacrylic acid 6 parts, n-dodecyl mercaptan 6 parts, azobisisobutyronitrile 6 parts A portion was weighed out, and the temperature was maintained at 65° C. for 7 hours while stirring at a rotation speed of 250 rpm to complete the reaction. The resulting suspension was filtered through a 200-mesh wire mesh to a size of 20μ~
Obtain pearl particles with a particle size of 600μ. This was ground in a ball mill for 24 hours, with an average particle size of 18μ and a maximum particle size of
The resin particles were made into 45 μm resin particles. The molecular weight of this resin is
It was 7600. Production Example 4 Production of Aqueous Resin-1 In a 2-liter reaction vessel equipped with a stirrer, temperature controller, and decanter, 273 parts of tall oil fatty acid, 197 parts of trimethylolpropane, 78 parts of neopentyl glycol, and 91 parts of hydrogenated bisphenol A were added. , 204 parts of isophthalic acid, 157 parts of trimellitic anhydride, xylene
Add 20 parts and raise the temperature while stirring. The reaction temperature was maintained at 180°C to 210°C, and the reaction was continued for 5 hours while removing the water produced to reach an acid value of 65 and an OH value.
100, number average molecular weight 1500, oil length 30. followed by ethylene glycol monobutyl ether
After adding 183 parts and 96 parts of dimethylethanolamine, dilute with deionized water to obtain an aqueous varnish with a non-volatile content of 50%. Production Example 5 Production of Aqueous Resin-2 In a reaction vessel similar to that used in the production of Aqueous Resin-1, 69 parts of trimethylolpropane, 297 parts of neopentyl glycol, 91 parts of hydrogenated bisphenol A,
201 parts of isophthalic acid, tetrahydrophthalic acid
Add 186 parts of trimellitic anhydride, 155 parts of trimellitic anhydride, and 10 parts of xylene, and raise the temperature while stirring. Reaction temperature 180
C. to 210.degree. C., and the reaction is continued for 5 hours while removing generated water to obtain a polyester resin having an acid value of 55, an OH value of 100, and a number average molecular weight of 1,500. followed by ethylene glycol monobutyl ether
After adding 183 parts of dimethylethanolamine and 82 parts of dimethylethanolamine, it is diluted with deionized water to obtain an aqueous varnish with a non-volatile content of 50%. Production Example 6 Production of Aqueous Resin-3 76 parts of ethylene glycol monobutyl ether was charged into a 1-liter reaction vessel equipped with a stirrer, a temperature controller, and a cooling tube, and further 45 parts of styrene, 63 parts of methyl methacrylate, and 2-hydroxyethyl were added. 48 parts of methacrylate, 117 parts of n-butyl acrylate
parts, 27 parts of methacrylic acid, 3 parts of lauryl mercaptan
61 parts of a monomer solution consisting of 1 part and 3 parts of azobisisobutyronitrile were added, and the temperature was brought to 120° C. with stirring. After 245 parts of the above monomer solution was added dropwise over 3 hours, stirring was continued for 1 hour. Add 28 parts of dimethylethanolamine and 200 parts of deionized water,
An acrylic resin varnish with a nonvolatile content of 50% and a resin number average molecular weight of 6000 was obtained. Production Example 7 Production of Aqueous Resin-4 In a 1-liter reaction vessel equipped with a stirrer, temperature controller, and cooling tube, 117 parts of dehydrated castor oil and 173 parts of soybean oil were added.
17 parts of glycerin, 61 parts of pentaerythritol,
After weighing out 132 parts of phthalic anhydride and adding 7.5 parts of xylene, the reaction was continued for 3 hours while keeping the temperature under stirring at 180°C to 220°C and removing water produced by the polyesterification reaction by azeotrope. Te, Yucho 57
%, acid value 10, and Mn 1800. This resin was diluted with xylene to obtain an alkyd resin varnish with a nonvolatile content of 60%. In a reaction vessel similar to that used for resin synthesis, 200 parts of the above alkyd resin varnish and 104 parts of ethylene glycol monobutyl ether were charged, and the temperature was lowered while stirring.
The temperature was set to 130℃. To this, 60 parts of styrene, 102 parts of methyl methacrylate, 65 parts of 2-hydroxyethyl methacrylate, 31 parts of acrylic acid, 143 parts of n-butyl acrylate, 6 parts of di-t-butyl peroxide,
A monomer solution consisting of 8 parts of lauryl mercaptan was added dropwise over 3 hours, and stirring was continued for another 1 hour to complete the reaction. The obtained vinyl-modified alkyd resin had an acid value of 50 and a molecular weight of 7,300. After neutralizing the above reaction solution 100% with dimethylethanolamine,
It was diluted with deionized water to give an aqueous varnish with a non-volatile content of 50%. Production Example 8 Production of Aqueous Resin-5 In a reaction vessel similar to that used in the synthesis of Aqueous Resin-1, 169 parts of neopentyl glycol, 6 parts of trimethylolethane, 46 parts of hydrogenated bisphenol A, 174 parts of isophthalic acid, and adipine were added. Prepare 65 parts of acid and 40 parts of maleic anhydride, add 10 parts of xylene, and continue the reaction for 4 hours while maintaining the temperature at 190 to 210°C with stirring and removing water produced by the polyesterification reaction azeotropically. As a result, a polyester resin having an acid value of 48 and a number average molecular weight of 1,200 was obtained. This resin was diluted with ethylene glycol monobutyl ether to remove the non-volatile content.
Made of 80% polyester resin varnish. In the production of the vinyl-modified alkyd resin in the latter stage of Production Example 7, instead of using 200 parts of the alkyd resin varnish and 104 parts of ethylene glycol monoethyl ether, 150 parts of the above polyester resin and 154 parts of ethylene glycol monobutyl ether were used in the same manner. A vinyl-modified polyester resin with an acid value of 50 and a molecular weight of 6,500 was obtained. This was 100% neutralized with dimethylethanolamine and diluted with deionized water to form an aqueous varnish with a non-volatile content of 50%. Examples 1 to 6 and Comparative Examples 1 to 2 Preparation of pigment paste.
Aqueous resin-1 obtained in Production Example 4, 320 parts of Taipeiku R-820 (Ishihara Sangyo, rutile type titanium oxide pigment), and 78 parts of deionized water were weighed out, and glass beads were added to 500 c.c. After premixing using a stirrer, the mixture was mixed and dispersed for 2 hours using a paint conditioner to obtain pigment paste-1. Also, instead of water-based resin-1, water-based resins-2, 3, 4, and 5 obtained in Production Examples 5 to 8
Pigment paste-2, 3, 4, 5 in the same manner using
I got it. Each material was weighed out in a stainless steel container according to the recipe shown in Table 1 below, and mixed with a stirrer at room temperature to obtain a coating composition. Each of the coating compositions of Examples 1-6 and Comparative Examples 1-2 was diluted with deionized water and placed in a #4 food cup.
The viscosity was adjusted to 30 seconds. Spray paint on the steel plate according to the usual method, set it for 15 minutes, and then heat it to 150℃.
A dry coating was obtained by baking for 15 minutes. The pinhole limit film thickness, sag limit film thickness, and gloss value for each composition are listed in the same table. However, film thickness limit pinhole film thickness limit sag ◎ 50μ or more ◎ 50μ or more 〇 40μ or more 〇 40μ or more △ 30~40μ △ 30~40μ × 30μ or less × 30μ or less Gloss value 60° at gloss value ◎ 90 or more 〇 85 or more △ 80 - 85 x 80 or less After painting, during curing and baking, craters or pinholes are formed on the coating surface as a result of water bumping and bubble removal. The thicker the coating film, the more likely this phenomenon will occur. Therefore, similar to the sag limit film thickness, the larger the pinhole limit film thickness, the higher the commercial value.

[Table] Reference Example 2 (Production of Comparative Resin Fine Particles 2) In a reaction vessel similar to that used in Production Example 1, 245 parts of deionized water and 25 parts of the seed emulsion from Production Example 1 were weighed out, and the temperature was adjusted. Bring to 80℃. Into this reaction vessel, under stirring, add 20 parts of deionized water and ammonium persulfate.
0.1 part of an aqueous solution was added followed by a pre-emulsion of 260 parts of methyl methacrylate, 235 parts of 2-ethylhexyl acrylate, 200 parts of deionized water, 0.6 parts of ammonium persulfate, and 0.3 parts of sodium dodecylbenzenesulfonate for 2 hours.
Drips in minutes. After the dropwise addition was completed, stirring was continued for 30 minutes, then an aqueous solution consisting of 20 parts of deionized water and 0.2 parts of ammonium persulfate was added, and stirring was continued for another hour to complete the reaction. The resulting emulsion has a non-volatile content
48.0%, and the average particle size of the contained resin particles is
The particle size was 2.4μ, and the maximum particle size was 3.8μ. Comparative Example 3 A comparative paint was prepared in the same manner as in Example 2 using the same formulation as in Example 2, but using the above Comparative Resin Particles 2 instead of Resin Fine Particles 2, and the coating film performance was examined after painting as follows. The results shown in Table 2 were obtained.

【table】

Claims (1)

[Scope of Claims] 1. In an aqueous coating composition containing as an essential component a binder component consisting of an aqueous resin and water-insoluble resin particles, the aqueous resin is a polyester resin, an alkyd resin, a vinyl resin, a vinyl-modified polyester resin, or a vinyl-modified polyester resin. The water-insoluble resin fine particles are at least one selected from the group consisting of modified alkyd resins, and the unsaturated compound having a polymerizable carbon-carbon double bond is subjected to two-stage emulsion polymerization in water in the presence of a seed emulsion. Polymerize legally,
By controlling the unsaturated compound composition at each stage,
The average particle size is 0.3, which has a double structure consisting of an inner shell of a hard polymer with a relatively high glass transition temperature and an outer shell of a soft polymer with a relatively low glass transition temperature.
It is vinyl resin fine particles of ~6μ, and the solid content weight ratio of the water-based resin and water-insoluble resin is 99:1 to 15:85.
A water-based paint composition characterized by: 2. The composition according to claim 1, wherein the weight ratio of the polymers constituting the inner shell and outer shell of the water-insoluble resin fine particles is 97-40-/3-60. 3 The average particle diameter of water-insoluble resin particles is 0.4 to 5μ
The composition according to any one of claims 1 to 2. 4 The number average molecular weight of the polymer constituting the outer shell is
Claims 1 to 3 range from 2,500 to 50,000.
The composition according to any of paragraphs.