JP3163327B2 - Blowing agent-containing coating composition and method for forming coating film using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a coating composition containing a foaming agent and a method for forming a coating film using the same. More specifically, the present invention relates to a coating composition containing a heat-expandable foaming agent, which forms a coating film having good coating film strength, heat insulation properties, and substrate hiding properties and has improved storage stability.

[0002]

2. Description of the Related Art A heat-expandable resin composition obtained by mixing a coating resin and a heat-expanding agent has a problem in that when a foreign substance from a road surface hits a road-side body portion of an automobile due to the structure of a coating film obtained using the same. It is used as a paint suitable for impact relaxation (chipping resistance). Also, after adding an emulsion and a thermal expansion agent to the thermally expandable resin composition and applying it in a pattern on a wallpaper by a silk screen method, when heated and expanded, the coating film expands and protrudes, and the uneven pattern is formed. It has also been used to make wallpaper.

[0003]

However, the coating film obtained from the above-mentioned heat-expandable resin composition has a weak coating film strength due to the inclusion of an air portion, and has poor scratch resistance and chemical resistance. There is a problem that it cannot be used where required. On the other hand, molded articles and die-cast articles on which a coating film of those resin compositions is formed are used to correct scratches, burrows, dents, spoils, and the like generated in their manufacturing processes.
In the finishing step of the coating, the putty is buried, and the operation of polishing the periphery of the buried part to finish it smoothly is added, so that the manufacturing process is complicated.

[0004] In recent years, the material of this type of object to be coated is not limited to metals such as aluminum and zinc, and the opportunity to use a lightweight, high-strength magnesium alloy or the like is increasing. However, magnesium alloys can cause fires due to metal powder generated in the polishing process, so the cost of equipment is high due to the need for local exhaust equipment, etc. Because of the reduction, there is a problem that the overall processing cost is increased.

[0005] Recently, barrier-free has become a keyword, and railroads and slopes for disabled persons and elderly people have been installed in public facilities such as stations and recreational facilities. Barrier-free orientation has penetrated, and railings and poles have been installed not only on stairs and corridors but also on toilets and bathrooms. Metals have been mainly used for these handrails and poles from the viewpoint of durability and strength.However, metal products have a cold feel when touched, especially a cold touch feeling in winter. This is a heavy burden for older people and those with weak hearts. As a countermeasure, there have also appeared metal linings made of vinyl chloride resin, etc., wooden ones, and plastic ones, but these have poor problems of contamination resistance, abrasion resistance and durability. There is a strong demand for the development of materials that are excellent in coating film strength and durability, etc. and that are warm.

[0006] The present invention has been made to solve the above-mentioned problems in the prior art. That is, an object of the present invention is to provide a coating composition capable of forming a coating film having good heat insulating properties and concealing properties of a base and obtaining a coating strength excellent in abrasion resistance and scratch resistance. Another object of the present invention is to provide a coating film forming method capable of eliminating a step of correcting a molded product or a die-cast product having a defective fabric by forming a coating film having a good base concealing property.

[0007]

The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems. As a result, a general capsule resin was used, and a microcapsule-type thermally expandable foaming agent and a particle size were added. By mixing a filler for reinforcing the coating film composed of resin beads of 10 to 100 μm at a fixed ratio, a coating composition capable of forming an undercoat concealing coating film having excellent coating film performance can be obtained. And completed the present invention.

Namely, the coating composition of the present invention, the base
An organic solvent for forming a concealable coating film
Inside, 70 to 94 parts by weight of a coating resin soluble in an organic solvent ,
Filler 5 consisting of resin beads having a particle size of 10 to 100 μm
20 parts by weight and microcapsule type thermal expansion type foaming agent 1
-10 parts by weight in a total amount of 100 parts by weight . The thermal expansion type foaming agent used in the present invention preferably has a thermal expansion temperature range common to the baking hardening temperature or the forced heating temperature of the coating resin. The packing, polymethacrylic acid, that are use <br/> the resin beads selected from polystyrene and polyurethane preferred. The coating film forming method of the present invention comprises applying the above coating composition to a substrate, and then heating to expand the thermal expansion type foaming agent to form a coating film having an air portion. It is characterized by the following.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The coating composition of the present invention contains at least a coating resin, a filler and a thermal expansion type foaming agent, and the coating resin includes a thermal expansion type foaming agent and a filler as a reinforcing agent for a coating film. Is added at a specific compounding ratio to form a coating film having improved coating film performance.

[0010] In the present invention, the thermal expansion type foaming agent is compounded to enclose air in the coating film, and a small-diameter foaming agent in which a gas such as hydrocarbon is filled in a thermoplastic plastic is used. Is done. As the thermal expansion type foaming agent, for example, a known microcapsule type foaming agent containing a hydrocarbon or the like in a shell of a thermoplastic such as vinylidene chloride resin is used. Microsphere F series (manufactured by Matsumoto Yushi Seiyaku Kogyo Co., Ltd.) and Expancel (manufactured by Akzo Nobel) are preferably used.

The thermal expansion type foaming agent in the coating composition of the present invention is selected in accordance with the coating purpose and application of the coating composition, and the temperature range in which the thermal expansion is performed is selected depending on the coating resin used. There must be. That is, in the case of the resin cross-linking paint, it is necessary to use a paint common to the bake hardening temperature range. In the case of lacquer paints (paints that do not crosslink), it must be forcibly heated to the foaming temperature of the thermal expansion foaming agent. If the baking curing temperature or the heating temperature is lower than the temperature range in which the thermal expansion type foaming agent expands by thermal expansion, the volume of the air portion in the coating film is reduced due to insufficient foaming. If the foaming agent is higher, the foaming agent that has once expanded contracts, so that the volume of the air portion also decreases, and the heat insulating property and the substrate concealing property decrease. The amount of the thermal expansion type foaming agent in the coating composition is,
It is in the range of 1 to 10 parts by weight, preferably 3 to 7 parts by weight. If the compounding amount is less than 1 part by weight, the volume of the air portion is reduced, and the heat insulating property and the base concealing property are reduced. On the other hand, if the compounding amount is more than 10 parts by weight,
The strength of the coating film is reduced, and the film is partially swollen to a large extent, so that a uniform foaming state cannot be obtained and the appearance is impaired.

[0012] In the present invention, the filler, which is blended to reinforce the film strength, the resin beads are used, specifically, polymethacrylates Sanshindama beads, polystyrene true sphere beads, Polyurethane sphere beads, epoxy sphere beads, benzoguanamine sphere beads, fluorine beads and the like are used, and commercially available art pearls (manufactured by Negami Industry Co., Ltd.) and scotch guards (manufactured by Sumitomo 3M Co., Ltd.) ) Or Labcolor (manufactured by Dainichi Seika Kogyo Co., Ltd.) is preferably used.

In the above fillers, polyacrylic Sanshin ball beads preferably in applications where coating film hardness in use material is required, also the strength of the coating film is not high, relative to an external shock In applications where resistance is required, it is preferable to use polyurethane spherical beads having a resilience to external impact. The shape is preferably a true sphere, but a scaly or square shape is slightly inferior to a true sphere, but does not pose any problem in practical use. The particle size is in the range of 10 to 100 μm, preferably 20 to 50 μm.
m. If the particle size is smaller than that, the concealing property of the base is reduced, while if it is larger than that, the appearance is impaired. The amount of the filler in the coating composition is from 5 to 20.
It is in the range of parts by weight, preferably in the range of 10 to 20 parts by weight. If the compounding amount is less than 5 parts by weight, the base concealing property is reduced and does not sufficiently contribute to the improvement of the strength of the coating film, while if it is more than 20 parts by weight, the strength of the coating film is reduced.

The coating resin in the present invention is usually used as a resin solution in which an organic resin is dissolved in an organic solvent. Acrylic resin,
Amino resin, polyester resin, epoxy resin,
Fluorine resin, polyurethane resin, alkyd resin and the like are listed. As the acrylic resin, any known resin for coatings can be used without any particular limitation, and the constituent components thereof include a soft main monomer component having a low glass transition temperature and a hard comonomer component having a high glass transition temperature. It is preferable to use a composition comprising a small amount of a functional group-containing monomer component, if necessary. Examples of the main monomer component include alkyl acrylates such as ethyl acrylate and butyl acrylate, and alkyl methacrylates such as butyl methacrylate and isobutyl methacrylate. Examples of the comonomer component include alkyl methacrylates such as methyl methacrylate and ethyl methacrylate, acrylonitrile, and styrene. Further, as the functional group-containing monomer component, 2-hydroxypropyl methacrylate,
3-hydroxypropyl methacrylate, 2-hydroxyethyl methacrylate and the like are used.

The amino resin can be used without any particular limitation as long as it is known for use in paints. Examples thereof include methylated melamine, butylated melamine, methylbutyl mixed alkylated melamine, methylbutyl mixed alkylated benzoguanamine, and methylolated melamine. Is used. The epoxy resin can be used without any particular limitation as long as it is known for coatings, and bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, novolak glycidyl ether, and the like are used.

The polyester resin can be used without any particular limitation as long as it is known for paints, and any resin obtained by condensation of a polyhydric alcohol and a polybasic acid can be used. As the polyhydric alcohol component, ethylene glycol, propylene glycol, dipropylene glycol, 1,3-butylene glycol,
2,3-butylene glycol, 1,6-hexanediol, 2-ethyl-1,3-hexanediol, 2,2
4-trimethyl-1,3-pentanediol, trimethylolethane, trimethylolpropane, glycerin and the like are used, while the polybasic acid components are phthalic anhydride, phthalic acid, terephthalic acid, isophthalic acid, tetrahydrophthalic acid , A saturated polybasic acid such as tetrahydrophthalic anhydride is used, and maleic anhydride, maleic acid,
Unsaturated polybasic acids such as itaconic anhydride, itaconic acid and fumaric acid can also be used in combination. In addition, tung oil, linseed oil, soybean oil,
Oil-modified polyester resins such as cottonseed oil, safflower oil and coconut oil can also be used. The molecular weight of these polyester resins is in the range of 500 to 50,000, preferably in the range of 1,000 to 30,000. Also,
The acid value is about 1 to 500, and the hydroxyl value is 2 to 2.
A value of about 00 is practical.

The polyurethane resin can be used without any particular limitation as long as it is known for paints. The polyisocyanate components include tolylene diisocyanate (TDI) and diphenylmethane diisocyanate (MD
I), hexamethylene diisocyanate (HDI), xylylene diisocyanate (XDI) or a polyisocyanate compound obtained by reacting these diisocyanates with a monomeric triol is used. As the polyol, a polyester polyol, a polyether polyol, an acrylic polyol, or the like is used.

The fluororesin can be used without any particular limitation as long as it is known for coatings. A fluoroolefin component such as chlorotrifluoroethylene or tetrafluoroethylene and an alkyl vinyl ether such as cyclohexyl vinyl ether or a higher carboxylic acid vinyl ester And a fluorine-containing copolymer obtained by copolymerizing a specific amount of a hydroxy group-containing monomer component such as hydroxyalkyl vinyl ether or hydroxyalkyl crotonate.
These can also be used as a lacquer type paint, and usually an isocyanate compound or a methylated melamine resin is used as a curing agent.

The alkyd resin can be used without any particular limitation as long as it is known for coatings, and a reaction product of a polyol having a monofunctional acid or alcohol added thereto and a dibasic acid or anhydride is used. Examples of the dibasic acid include orthophthalic acid, isophthalic acid, terephthalic acid, maleic acid, fumaric acid, adipic acid, sebacic acid, orthophthalic anhydride, and maleic anhydride. The polyol is glycerol or pentaerythritol, but a small amount of sorbitol or trimethylolpropane is also used. For the monofunctional acid or alcohol for esterification, a long-chain fatty acid or alcohol is used, and the long-chain fatty acid is used alone or in the form of a mixture of a plurality of oils, for example, by esterification with glycerol. Use as a triacylglycerol that dissolves at room temperature. Commonly used oils are linseed oil or soybean oil.

The coating composition of the present invention is used by dissolving a coating resin in an organic solvent. Examples of the organic solvent include hydrocarbons such as benzene, toluene, and xylene, esters such as methyl acetate, ethyl acetate, and butyl acetate, ethers such as ethyl ether, butyl ether, methyl cellosolve, ethyl cellosolve, and tetrahydrofuran, ethylene glycol, and ethylene. Glycol derivatives such as glycol monoethyl ether and ethylene glycol mono n-propyl ether are used. By the way, in the present invention, methanol, ethanol,
Alcohols such as isopropyl alcohol and n-butanol are not suitable for use, and particularly, methanol,
Lower alcohols (those having short alkyl chains) such as ethanol cannot be used. Also, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and dimethyl isobutyl ketone are not suitable for use like alcohols. These alcohols or ketones mean that the core constituting material of the thermal expansion type foaming agent has a high dissolving power, and the presence of these organic solvents makes it possible to store the coating composition in a capsule type. This is because the components constituting the core of the foaming agent are eluted from the shell, and when thermally expanded, the core does not already exist in the shell, so that foaming stops.

In the coating composition of the present invention, when a thermally expandable foaming agent and a filler are added to the coating resin dissolved in the above organic solvent, the thermally expandable foaming agent and the filler are added to the coating resin. It is necessary that the agent is uniformly dispersed and stabilized,
Therefore, dispersion is performed using various dispersers such as a ball mill, a three-roll mill, a dyno mill, a bead mill, and a disper. However, when excessive tension is applied to the coating composition due to the dispersion, the thermal expansion type foaming agent may damage the partition walls and may not be able to perform a normal function. It is necessary to set conditions.

Hitherto, it has been expected that a paint containing a foaming agent will form a coating film having excellent heat insulating properties and concealing properties of the underlayer due to the structure of the resulting coating film. However, since the obtained coating film has low structural strength, there is no example of practical use in applications where abrasion resistance and scratch resistance are required.
In addition, the practical use in the market such as the patterned portion of the wallpaper and the anti-chipping paint of the car is limited. However, in the coating composition of the present invention, a thermal expansion type foaming agent is blended together with a filler as a reinforcing agent for the coating film, and the baking drying temperature range or curing temperature range of the coating resin used as a binder component is determined. With a composition designed to link the thermal expansion temperature range of the mold foaming agent, it was possible to greatly improve the performance of the coating film, particularly the abrasion resistance and the abrasion resistance. That is, for example, the coating composition of the present invention is applied to a metal material where abrasion resistance, scratch resistance and stain resistance are required in door knobs, handrails, poles, etc. which frequently touch the human hand. By forming the film, durability and strength can be maintained, and a warm material can be realized.

The repair work such as padding and polishing, which has been conventionally performed in order to correct scratches, burrows, dents and spoils, which occur in the process of producing a molded product or a die-cast product, are described in the present invention. By forming a coating film of the coating composition of the above, the number of repair work steps can be reduced. Thereby, in the present invention, it is possible to simplify the manufacturing process, and for a special metal such as a magnesium alloy, it is possible to omit a polishing process involving a danger of fire due to powder generated in the polishing process, It can also contribute to ensuring safety.

Next, the method of using the coating composition of the present invention will be described. The coating composition solution prepared for a coating material as described above is applied on a substrate, and is forcibly dried to obtain a baked and dried coating film. The base material is iron, stainless steel, aluminum, brass, magnesium alloy, zinc alloy, other metals, glass, ABS resin, polystyrene, polyester resin, polycarbonate, vinyl chloride resin, acrylic resin, and other plastics. Can be used.

The conditions for the forced drying are as follows: the temperature is within a temperature range in which the coating resin used as a binding component of the polymer undergoes a curing reaction, and the time is such that the curing reaction of the coating resin is sufficiently performed. Any time range is acceptable. In any of the resin system, in the case of a lacquer paint, it may be at 80 ° C. or more is foamed starting temperature of low-temperature bubbling grade thermal expansion foaming agent. However, in this case, baking and drying must be performed within the foaming temperature range of the thermal expansion foaming agent used. On the other hand, in the case of the resin cross-linking type in which the coating film is formed by a cross-linking reaction, the progress of the resin cross-linking and the evaporation state of the solvent affect the foaming state of the thermal expansion foaming agent. In particular, since the maximum foaming temperature may deviate from the catalog value of the thermal expansion type foaming agent, it is necessary to carefully select the thermal expansion type foaming agent. If the curing temperature of the coating resin used as the binder component and the thermal expansion temperature of the thermal expansion type foaming agent are not linked, the object of the present invention can be achieved because the base concealing property and the heat insulating effect cannot be sufficiently obtained. It is difficult. For example, when a two-component system containing a polyester resin and an amino resin is used as a resin varnish for a paint, and a thermally expandable foaming agent that foams in the range of 100 to 170 ° C. is used, and baking and drying is performed at 210 ° C. for 3 minutes. Cannot hide the scratches on the base. Similarly, a two-component system containing an acrylic resin and a polyurethane resin is used.
Baking and drying at 8 to 170 ° C.
Even when the test was performed at 0 ° C. for 30 minutes, the scratches on the base were not concealed.

The method of applying the coating resin composition to a substrate may be selected from known coating methods such as a dipping method, an air spray method, an airless spray method, a roll coater, and a gravure coater. , Required film thickness,
It is appropriately selected in consideration of the properties of the paint and the like. The thickness of the coating film formed by baking hardening is preferably in the range of 10 to 50 μm. When the film thickness is 10 μm or less, the protective effect of the coating film is reduced, the coating film defects such as pinholes are easily generated, and the concealment property of scratches and dents on the base is also reduced. On the other hand, if the thickness is more than 50 μm, cracks are likely to occur, and the adhesion decreases due to internal stress during the formation of the coating film. In addition, when painting a molded product, the components are often combined after painting, and in such a case, it is difficult to combine the fitting portions.

Further, the coating composition of the present invention comprises a pigment,
It can be used as a coloring paint containing a coloring agent such as a dye. Examples of pigments used in the paint include white pigments such as titanium oxide, calcium carbonate, barium sulfate, talc, and alumina; black pigments such as carbon black and black iron; blue pigments such as phthalocyanine blue; Red pigments such as yellow pigment, red iron, lake red and the like can be mentioned. Furthermore, the coating composition of the present invention, if necessary, other additives for resins, for example, ultraviolet absorbers, antioxidants, antistatic agents, conductivity imparting agents, slip agents, anti-sagging agents, An antifoaming agent, a leveling agent, a thixotropic agent, and the like can be appropriately compounded.

[0028]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples and the like, but the present invention is not limited to the following Examples as long as the gist of the present invention is not exceeded. [Preparation of paint resin] (A) 50 g of acrylic resin / amino resin two-component acrylic resin varnish (Dianal HR-632, manufactured by Mitsubishi Rayon Co., Ltd., solid content 50%, acid value 7) and methylated melamine resin varnish ( 15 g of Cymel 370 (manufactured by Mitsui Cytec Co., Ltd., solid content: 80%) was further mixed, and the mixed solution was diluted with a mixed solvent consisting of 10 g of n-butanol, 10 g of ethyl acetate and 7.5 g of toluene to obtain an acrylic resin. And 92.5 g of a two-component resin varnish for coatings containing an amino resin. The bake hardening temperature range of the resin varnish A for coating is 140 ° C. × 30 minutes to 18 ° C.
0 ° C. × 20 minutes.

(B) Two-component polyester resin / amino resin polyester resin (Polyester TP-290, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., molecular weight 17000, polycondensate of propylene glycol and phthalic anhydride) (40 g) and methylation 3 g of melamine resin varnish (Cymel 370, manufactured by Mitsui Cytec Co., Ltd., solid content: 80%) was mixed, and the mixed solution was further diluted with a mixed solvent consisting of 25 g of n-butanol, 25 g of ethyl acetate and 14 g of toluene, 107 g of a two-component resin varnish B for a coating material containing a polyester resin and an amino resin was obtained. This resin varnish B for paint
The bake hardening temperature range is from 140 ° C x 30 minutes to 210 ° C
× 3 minutes. (C) 50 g of an alkyd resin / amino resin / epoxy resin ternary alkyd resin varnish (ULIX 210S, manufactured by Mitsui Toatsu Chemicals, oil length 38%, phthalic acid 43%, nonvolatile content 70%), and methylated melamine Resin varnish (Cymel 370, manufactured by Mitsui Cytec, solid content 80%) 1
5 g and 4.2 g of an epoxy resin varnish (Epicoat 1001, manufactured by Yuka Shell Co., Ltd., obtained by dissolving 10 g of epoxy equivalent 475 in 6.7 g of toluene) and further mixing this mixed solution with 20 g of n-butanol, A three-component paint resin varnish C123.8 containing an alkyd resin, an amino resin and an epoxy resin, diluted with a mixed solvent consisting of 20 g of ethyl acetate and 14.6 g of toluene.
g was obtained. The bake hardening temperature range of the resin varnish C for coating is from 140 ° C. × 20 minutes to 180 ° C. × 15 minutes.

(D) Two-component fluorine resin / polyurethane resin fluorine resin varnish (Zeffle GK-510, manufactured by Daikin Industries, nonvolatile content 50%, hydroxyl value 60) and polyisocyanate (Takenate D-140N, Takeda Pharmaceutical) Company, IPDI system, NCO% 10.5, Non-volatile content 75
%) And 10.5 g of the resulting mixture.
-8 g of butanol, 8 g of ethyl acetate and 5.7 of toluene
g of a two-component resin varnish D for coating containing a fluororesin and a polyurethane resin. The baking hardening temperature range of the resin varnish D for coating is from 100 ° C. × 20 minutes to 140 ° C. × 15 minutes. (E) Two-component acrylic resin / polyurethane resin acrylic resin varnish (Acrydic A-807, manufactured by Dainippon Ink and Chemicals, Inc., hydroxyl value 25, nonvolatile content 50)
%) And polyisocyanate (Takenate D-14)
0N, manufactured by Takeda Pharmaceutical Company, IPDI system, NCO% 10.
5, nonvolatile content 75%) and 9.8 g, and further dilute this mixed solution with a mixed solvent consisting of 8 g of n-butanol, 8 g of ethyl acetate and 5.1 g of toluene to obtain an acrylic resin and a polyurethane resin. 80.9 g of a two-component resin varnish for coatings containing The bake hardening temperature range of the resin varnish E for coating is from 80 ° C. × 30 minutes to 120 ° C. × 15 minutes.

Example 1 Acrylic resin varnish (solid content 50%, acid value 7) 50 g (Dianal HR-632, manufactured by Mitsubishi Rayon Co., Ltd.) Methylated melamine resin varnish (solid content 80%) 15 g (Cymel 370, Mitsui The above resin varnish was put in a 300 ml stainless steel container and mixed, and then the mixture was diluted with a mixed solvent consisting of 10 g of n-butanol, 10 g of ethyl acetate and 7.5 g of toluene to thereby form an acrylic resin and amino resin. 92.5 g of a two-component resin varnish for paint containing a resin (resin varnish A for paint) was obtained. The baking hardening of the resin varnish A for coating was performed under the conditions shown in Table 1 (at 140 ° C. for 30 minutes).
Went under. Next, 92.5 g of the resin varnish for the paint.
1.35 g of the following thermal expansion type foaming agent and 2.7 g of a filler (Rabcolor F, manufactured by Dainichi Seika Kogyo Co., Ltd., polymethacrylic acid beads, particle size of about 20 μm) were added to improve dispersibility. Was filled with 50 cc of 1 mmφ glass beads. Using a disperser (TK homodisper, manufactured by Tokushu Kika Kogyo Co., Ltd., impeller diameter: 3 cm blade)
The mixture was dispersed at 0 rpm for 20 minutes, and the entire amount of the obtained dispersion was filtered using a 100-mesh wire net to obtain a coating composition. "Thermal expansion type foaming agent" Product name: Matsumoto Microsphere F-40 (manufactured by Matsumoto Yushi Pharmaceutical Co., Ltd.) (particle diameter: about 15 μm, thermal expansion start temperature: about 100 ° C., thermal expansion temperature range: 100 to 170 ° C., expanding agent) : Isobutane / isopentane)

Examples 2 to 5 In Example 1, as shown in Table 1, except that the blending amounts of the thermal expansion type foaming agent and the filler were changed, the same procedure as in Example 1 was carried out. A composition was obtained.

Comparative Examples 1 to 3 As shown in Table 1, each coating composition was obtained without blending one or both of the thermal expansion type foaming agent and the filler in Example 1.

Example 6 The procedure of Example 1 was repeated except that 92.5 g of a two-component paint resin varnish C containing the polyester resin and amino resin was used as the paint resin varnish.
Was obtained in the same manner as described above. Example 7 In Example 1, it carried out similarly to Example 1 except having used 92.5 g of three-component paint resin varnishes D containing the alkyd resin, amino resin, and epoxy resin as a paint resin varnish. Thus, a coating composition was obtained.

Example 8 In Example 1, as a thermal expansion type foaming agent, Matsumoto Microsphere F-20 (trade name, manufactured by Matsumoto Yushi Pharmaceutical Co., Ltd., particle diameter: about 15 μm, thermal expansion onset temperature: about 80 ° C., heat A coating composition was obtained in the same manner as in Example 1 except that an expansion temperature range of 80 to 140 ° C and an expanding agent: isobutane) were used. Example 9 In Example 1, as a thermal expansion type foaming agent, Matsumoto Microsphere F-100 (trade name: manufactured by Matsumoto Yushi Pharmaceutical Co., Ltd., particle diameter: about 20 μm, thermal expansion start temperature: about 140)
A coating composition was obtained in the same manner as in Example 1 except that a temperature of 140 ° C., a thermal expansion temperature range of 140 to 210 ° C., and an expanding agent: isobutane) were used.

Example 10 As a resin varnish for paint, a two-component resin varnish E9 containing the above-mentioned acrylic resin and polyurethane resin was used.
Using 2.5 g, as a thermal expansion type foaming agent, trade name: Matsumoto Microsphere F-20 (manufactured by Matsumoto Yushi Pharmaceutical Co., Ltd., particle size: about 15 μm, thermal expansion start temperature: about 80 ° C., thermal expansion temperature range: 80 to 80 ° C.) A coating composition was obtained in the same manner as in Example 1 except that 140 ° C. and an expanding agent: isobutane) were used.

The amount of each component in the coating compositions in Examples 1 to 10 and Comparative Examples 1 to 3, the thermal expansion temperature range of the thermal expansion foaming agent used, and the Table 1 shows the baking hardening conditions for forming the coating film.

[Table 1]

[Preparation of Specimen with Coated Film] Using the coating compositions obtained in Examples 1 to 10 and Comparative Examples 1 to 3, a die casting material (AZ) of a magnesium alloy was used.
91, 150 × 100 × 2 mm), and treated under the baking hardening conditions shown in Table 1 to obtain a dry coating film adhesion amount of 30 g / m ² (film thickness of 30 μm).
m) was obtained and used as a test piece. The test piece made of the above die-cast material has a depth of 2
Those having scratches of 00 to 300 μm were used.

[Evaluation method of baked coating film] 1) Adhesion: The adhesion between the coating film and the substrate is determined according to JIS K5.
It was measured based on 400 and evaluated. 2) Pencil hardness: The degree of damage of the coating film is JIS K 5400.
Was measured and evaluated. 3) Weather resistance: Evaluation was performed according to an exposure test of an arc carbon type sunshine weatherometer. The test was performed at a temperature of 63 ° C., a rainfall time of 12 minutes, and a rainfall cycle of 60 minutes. The evaluation criterion was that the exposure time was 1000 hours and the coating film before and after the test was 60 hours.
The measurement was performed by measuring gloss change and color difference. For color difference measurement,
Minolta CR-300 was used. 4) Concealing property of base The finished appearance of the test piece was visually judged. 5: good with no visible scratches; 4: barely visible scratches; 3: slightly visible scratches; 2: visible scratches; 1: good visible scratches. Table 2 shows the results obtained by the above 1) to 4).
Shown in

[0040]

[Table 2]

5) Heat insulation effect of coating film Each of the test pieces on which the above-mentioned coating film was formed was cooled to 0 ° C and brought into contact with the back of a man in his 20s for 3 seconds.
About the temperature change at the place where the test piece on the back touched,
The measurement was performed using thermography from the lapse of 10 seconds to the lapse of 60 seconds in units of 10 seconds. Table 3 shows the measurement results of the temperature at the contact point for each elapsed time of the test piece.

[0042]

[Table 3]

[0043]

As described above, the coating composition of the present invention contains a specific thermal expansion type foaming agent and a filler and forms a coating film in a specific forced drying temperature range. The coating film formed by using is excellent in heat insulating property and concealing property of the base, has high mechanical strength such as abrasion resistance and scratch resistance, and has coating performance excellent in long term weather resistance. Things. Further, according to the present invention, since a good undercoating film is formed using the above coating composition,
It is possible to obtain a simple coating film forming method capable of reducing the number of steps for correcting a base material such as a molded product or a die-cast product having a defective fabric.

Claims (3)

(57) [Claims] 1. An organic solvent containing 70 to 94 parts by weight of a coating resin soluble in an organic solvent and having a particle size of 10 to 100 μm.
5 to 20 parts by weight of a filler comprising a microcapsule
100 parts by weight of 1 to 10 parts by weight of thermal expansion type foaming agent
Base concealment characterized by being blended so as to be part
A coating composition for forming a water- soluble coating film . 2. The coating composition according to claim 1, wherein the thermal expansion type foaming agent has a thermal expansion temperature range common to the baking hardening temperature or the forced heating temperature of the coating resin. object. 3. After application of the coating composition according to the substrate to Claim 1, by foaming the thermal expansion foaming agent to form a basecoat hiding property of the coating film is present air portion by heating Method.