JP2006335918A - Resin composition, coating composition, coated film and method for forming coated film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin composition and a coating composition each forming a formed product and a coated film each having a new internal structure and excellent in acoustic properties, heat-insulating properties and vibration-damping property. <P>SOLUTION: The resin composition and the coating composition each comprises inorganic fine particles of which surface is sprinkled with a foaming agent and a resin. The inorganic fine particles are selected from a metal, a metal oxide, an alloy, a fine particles of magnetic substance, ceramics and glass and these fine particles are applied in a form of plastisol or water-based emulsion to the resin and the resultant composition is heated to expand the composition. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is excellent in chipping performance and soundproofing / vibration / absorbing properties, and is preferably a resin composition, a coating composition, and a coating film that are suitable for automotive paints applied to the under floor of automobiles, foil houses, etc. And a method for forming a coating film.

  A so-called chipping phenomenon in which a coating film is peeled off due to a collision of pebbles or gravel that a tire jumps up when a vehicle travels occurs in an under floor portion or a wheel house portion of an automobile. Furthermore, a collision sound due to the collision of the pebbles and gravel, so-called splash sound is also generated. For this reason, conventionally, in order to prevent this chipping phenomenon and reduce the splash sound, a soundproof undercoat using a polyvinyl chloride plastisol is applied to the surface of the automobile steel plate after the painting process, and dried. Forming a coating film for protecting a vehicle body is performed.

  Patent Document 1 discloses a vinyl chloride plastisol composition blended with a hollow filler, and Patent Document 2 blends an organic hollow filler that expands by heating or a specific amount of a foaming agent into an aqueous coating composition. Although water-based paints for vehicle members have been disclosed, all are aimed at vibration proofing / damping at 100 Hz or less, and there is no teaching regarding absorption and sound insulation.

  Therefore, Patent Document 3 discloses a coating composition in which magnetic fluid-containing microcapsules are mixed. Specifically, the magnetic fluid-encapsulated microcapsule comprises an outer shell and a magnetic fluid contained therein, and the magnetic fluid is obtained by dispersing magnetic fine particles having an average particle diameter of 5 to 200 nm in a hydrophobic organic solvent. Yes, the outer shell is a thermoplastic resin.

Patent Document 4 discloses a method for producing a sound absorbing and insulating composite plastic panel in which fiber reinforced plastic is integrally formed on at least one surface of a plastic sheet containing a magnetic fluid-containing capsule. Specifically, it has been proposed that a plastic sheet containing a magnetic fluid-encapsulated capsule is laminated and placed on a fiber-reinforced plastic molding material, and cured and molded by pressing.
JP-A-4-145174 JP 7-145331 A Japanese Patent No. 3357070 JP-A-9-248835

  As disclosed in Patent Document 3, when the microcapsules are mixed in the paint, the capsules in the outer shell are damaged during kneading, and there is a problem that sufficient performance cannot be obtained.

  In addition, when the method for producing a sound-absorbing and sound-insulating composite plastic panel containing a magnetic fluid-encapsulating capsule disclosed in Patent Document 4 is applied to a production line of an automobile or the like, installation of such a press-molded product is limited in the attachment site. In addition, the attachment process is limited to the final assembly process, which is not practical.

  Furthermore, automobiles have various complicated and curved surface portions, and a soundproofing effect is often required for those portions. In addition, there are many space constraints, and in addition, weight reduction must be achieved. In that sense, lamination and press molding are very disadvantageous.

  Therefore, an object of the present invention is to provide a slush molded body having a novel internal structure and excellent in sound absorbing property, sound insulating property, and vibration damping property.

  The present inventors have found that the above problems can be solved by a resin composition and a coating composition having a specific composition, and have reached the present invention.

  That is, first, the present invention is an invention of a resin composition, characterized by containing inorganic fine particles coated with a foaming agent on the surface. The foam is foamed in the process of heating and molding the resin composition, and the inorganic fine particles are confined in the produced foamed cell to form a bell-shaped cell. Here, the bell-shaped cell is a cell having a bell-like structure having a large number of pores (cells) inside and particles that can move independently in the pores (cells). . The resin molded product obtained by molding the resin composition of the present invention is excellent in sound absorption, sound insulation, and vibration control because sound energy and vibration energy are converted into kinetic energy of inorganic fine particles in the pores (cells). ing.

  Secondly, the present invention is an invention of a coating composition, characterized by containing inorganic fine particles coated with a foaming agent on the surface. The foam is foamed in the step of heating the coating composition, and the inorganic fine particles are confined in the produced foamed cell to form a bell-shaped cell. Here, the bell-shaped cell is a cell having a bell-like structure having a large number of pores (cells) inside and particles that can move independently in the pores (cells). . The coating film on which the coating composition of the present invention is formed has excellent sound absorption, sound insulation and vibration damping properties because sound energy and vibration energy are converted into kinetic energy of inorganic fine particles in the pores (cells). ing.

  The inorganic fine particles used in the present invention are not particularly limited as long as the specific gravity is larger than a predetermined value. Specifically, one or more selected from metals, metal oxides, alloys, magnetic fine particles, ceramics, and glass are preferably exemplified.

  In order to exhibit excellent sound absorption, sound insulation and vibration damping properties, the average particle size of the inorganic fine particles in the bell cell is preferably 5 to 500 nm, and the specific gravity is preferably 1.0 to 5.0. .

  On the other hand, the average particle diameter of the pore cells serving as the outer shell of the bell-shaped cell is preferably 5 to 500 μm in view of the balance with the average particle diameter of the inorganic fine particles in the bell-shaped cell.

  Although the form of the coating composition of this invention is not specifically limited, It is preferable that they are a plastisol coating and a water-system emulsion coating. That is, it is preferably a plastisol mainly composed of resin powder and a plasticizer, or an aqueous emulsion mainly composed of a water-soluble resin.

  Third, the present invention is an invention of a coating film, comprising a bell-shaped cell having pores inside the coating film and containing inorganic fine particles that can move independently of the pores (cells) in the pores. Contains. The coating film of the present invention is excellent in sound absorption, sound insulation and vibration damping.

  The coating film of the present invention is particularly excellent in sound absorbing properties, sound insulating properties and vibration damping properties when part or all of the pores (cells) in the coating film form open cells. The reason why the sound absorbing property, sound insulating property and vibration damping property are particularly excellent is not necessarily clear, but it is thought that the sound entering the coating film passes through the open bubbles while being attenuated compared to the case of independent bubbles. It is done.

  In the present invention, the details of the bell-shaped cell are not limited. For example, the inorganic particles in the bell-shaped cell have an average particle diameter of 5 to 500 nm and a specific gravity of 1.0 to 5.0. It is preferable because of its excellent properties, sound insulation and vibration control. Moreover, it is preferable that the average particle diameter of the void | hole (cell) which forms a bell-shaped cell is 5-500 micrometers.

  4thly, this invention is invention of a coating-film formation method, The process of apply | coating the coating composition which uses the inorganic fine particle which coat | covered the foaming agent on the surface, and resin as a coating-film component to the target object, and was obtained By heating the coating material to foam the foaming agent and forming a coating film, inorganic fine particles that have pores inside the coating film and can move independently of the pores (cells) are included in the pores. A coating film containing bell-shaped cells is formed.

  Here, when the process of heating the said applied material serves as the process of drying a coating film, it is preferable on a coating-film formation process.

  The use of the coating composition of the present invention is not particularly limited, and there is a bell-shaped cell having a bell-like structure having a large number of pores inside and particles that can move independently of the substrate in the pores. It is used for various applications by taking advantage of the excellent sound absorption, sound insulation and vibration control properties that are exhibited by being formed in the coating film. For example, paints for automobiles, paints for aircraft, paints for trains, paints for housing of home appliances, paints for exterior walls of buildings, paints for lining materials, paints for roofing materials, or paints for soundproof walls on expressways and railway lines It is used suitably for etc.

  Particularly, fifthly, the present invention is a soundproof / vibration / sound absorbing paint comprising the above-mentioned paint composition, and sixthly, the present invention is an automobile paint comprising the above-mentioned paint composition. Seventh, the present invention is an automobile having the coating film.

  The resin molded body molded from the resin composition of the present invention and the coating film formed from the coating composition of the present invention have a large number of pores inside, and the pores are independent of the substrate. By having a bell-shaped cell having a bell-shaped structure having inorganic fine particles that can move, vibration energy is efficiently absorbed, and excellent sound absorbing properties, sound insulating properties and vibration damping properties are exhibited. The coating film formed from this coating composition is suitably used for various applications such as automotive coatings, architectural coating interior coatings, and architectural exterior coatings.

  FIG. 1 schematically shows the formation of a coating film containing bell cells containing the inorganic fine particles of the present invention. After coating a coating composition containing inorganic fine particles coated with a foaming agent on the surface and resin powder as a coating film component on an object, the obtained coating is heated to foam the foaming agent as shown in FIG. When the coating film is formed, a coating film containing bell-shaped cells containing pores in the coating film and containing inorganic fine particles that can move independently of the pores (cells) is formed. The It is considered that the inorganic fine particles that can move independently of the base body in the bell-shaped cell efficiently absorb vibration energy and exhibit excellent sound absorption, sound insulation, and vibration control.

  FIG. 2 schematically shows a case where a coating film containing bell-shaped cells encapsulating the inorganic fine particles of the present invention is formed on the bottom of an automobile body, particularly a wheel house. The coating film of this invention is formed in the steel plate which comprises a vehicle body through an electrodeposition layer (ED). The plastisol paint becomes a coating film containing bell cells containing inorganic fine particles inside through a heating process. As described with reference to FIG. 1, the inorganic fine particles that can move independently of the substrate in the bell-shaped cell efficiently absorb vibration energy and exhibit excellent sound absorption, sound insulation, and vibration control.

  In the present invention, the resin material of the resin composition in which inorganic fine particles are encapsulated in pores (cells) is not particularly limited. Specifically, polyethylene, polypropylene, polyvinyl alcohol, polyvinylidene chloride, polyethylene terephthalate, polyvinyl chloride, polystyrene, ABS resin, AS resin, acrylic resin, polyamide, polyacetal, polybutylene terephthalate, glass reinforced polyethylene terephthalate, polycarbonate, modified Thermoplastic resins such as polyphenylene ether, polyphenylene sulfide, polyether ether ketone, liquid crystalline polymer, fluororesin, polyarate, polysulfone, polyethersulfone, polyamideimide, polyetherimide, thermoplastic polyimide, phenol resin, melamine resin, urea Resin, epoxy resin, unsaturated polyester resin, alkyd resin, silicone resin, diallyl phthalate resin, poly Bromide bismaleimide, poly bisamide thermosetting resin triazole and the like, and it is possible to use two or more kinds of these blended material.

  In the present invention, the material of the inorganic fine particles contained in the pores (cells) is not particularly limited, but metal oxide fine particles, ceramic fine particles, metal fine particles, magnetic fine particles, and the like are used.

  Usually, the paint contains a resin as an essential component, and optionally contains one or more of a pigment, a solvent, water, various additives, and the like. The content ratio of these components is appropriately selected according to the required characteristics of the paint, and is various ratios. Examples of the resin include polyester resin, acrylic resin, polyurethane resin, melamine resin, and epoxy resin. Examples of the pigment include inorganic pigments such as titanium oxide, carbon black, talc, and clay, phthalocyanine-based, azo And organic pigments such as quinacridone and the like. Solvents include aromatic hydrocarbons such as toluene and xylene, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, alcohols such as ethanol, isopropanol and butanol, ethyl acetate, Examples thereof include esters such as isopropyl acetate and butyl acetate, and glycol ester solvents such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and ethylene glycol monobutyl ether.

  The water-soluble resin used in the emulsion paint is preferably a water-soluble resin having an acid value of 20 to 70 mgKOH / g and a hydroxyl value of 20 to 160 mgKOH / g. Specifically, polyester resin, acrylic resin, and polyurethane resin are used. Particularly preferred. The polyester resin suitably used as the water-soluble resin is obtained by using a polyhydric alcohol and a polybasic acid as a resin raw material, and has an acid value of 20 to 70 mgKOH / g, preferably 25 to 60 mgKOH / g, particularly preferably 30 to It is a water-soluble resin having a hydroxyl value of 55 to Kmg / g and a hydroxyl value of 20 to 160 mgKOH / g, preferably 80 to 130 mgKOH / g.

  The water-soluble polyester resin can be easily obtained by a known esterification reaction using a polyhydric alcohol, a polybasic acid and, if necessary, fats and oils constituting a normal polyester resin as a resin raw material. Examples of the polyhydric alcohol include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butylene glycol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, and dipropylene. Examples include glycol, neopentyl glycol, triethylene glycol, hydrogenated bisphenol A, glycerin, trimethylol ethane, trimethylol propane, pentaerythritol, and dipentaerythritol. These polyhydric alcohols may be used alone or in combination of two or more. Examples of the polybasic acid include phthalic anhydride, isophthalic acid, terephthalic acid, succinic anhydride, adipic acid, azelaic acid, sebacic acid, maleic anhydride, fumaric acid, itaconic acid, trimellitic anhydride, and the like. Can do. These polybasic acids may be used alone or in combination of two or more. Examples of the fats and oils include soybean oil, coconut oil, safflower oil, bran oil, castor oil, persimmon oil, linseed oil, tall oil, and fatty acids obtained therefrom.

  The acrylic resin suitably used as the water-soluble resin is obtained by using a vinyl monomer as a resin raw material, and has an acid value of 20 to 70 mgKOH / g, preferably 22 to 50 mgKOH / g, particularly preferably 23 to 40 mgKOH / g. A water-soluble resin having a hydroxyl value of 20 to 160 mgKOH / g, preferably 80 to 150 mgKOH / g.

  The water-soluble acrylic resin can be easily obtained by a known solution polymerization method using an organic peroxide as an initiator, using a vinyl monomer constituting a normal acrylic resin as a resin raw material. Examples of vinyl monomers include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, and crotonic acid, acrylic acid or methacrylic acid methyl, ethyl, propyl, butyl, isobutyl, Alkyl esters such as tertiary butyl, 2-ethylhexyl, lauryl, cyclohexyl, stearyl, hydroxyalkyl such as 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl of acrylic acid or methacrylic acid, polyethylene glycol having a molecular weight of 1000 or less Esters, amides of acrylic acid or methacrylic acid or their alkyl ethers such as acrylamide, methacrylamide, N-methylol acrylamide, diacetone acrylamide, diacetate Down methacrylamide, N- methoxymethyl acrylamide, N- methoxymethyl methacrylamide, N- butoxymethyl acrylamide.

  Furthermore, glycidyl (meth) acrylate having an epoxy group and monomers containing a tertiary amino group, for example, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate and the like can be mentioned. . In addition, aromatic monomers such as styrene, α-methylstyrene, vinyltoluene, and vinylpyridine, acrylonitrile, methacrylonitrile, vinyl acetate, maleic acid, and mono- or dialkyl esters of fumaric acid can be used. Examples of the organic peroxide include acyl peroxides (for example, benzoyl peroxide), alkyl hydroperoxides (for example, t-butyl hydroperoxide, p-methane hydroperoxide), dialkyl peroxides (for example, , Di-t-butyl peroxide) and the like.

  The polyurethane resin suitably used as the water-soluble resin is obtained by using polyol and polyisocyanate as raw materials, and has an acid value of 20 to 70 mgKOH / g, preferably 22 to 50 mgKOH / g, particularly preferably 23 to 35 mgKOH / g. A water-soluble resin having a hydroxyl value of 20 to 160 mgKOH / g, preferably 25 to 50 mgKOH / g.

  The water-soluble polyurethane resin can be easily obtained by addition polymerization using a polyol and a polyisocyanate constituting a normal polyurethane resin as the resin raw material.

  Examples of the polyol include polyester polyol, polyether polyol, acrylic polyol and the like. Polyisocyanates include phenylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate, bisphenylene diisocyanate, naphthylene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, cyclopentylene diisocyanate, cyclohexylene diisocyanate, methylcyclohexylene diisocyanate, dicyclohexylmethane diisocyanate. , Trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, propylene diisocyanate, ethylethylene diisocyanate, trimethylhexane diisocyanate and the like.

  Water-soluble polyester resins, acrylic resins, polyurethane resins and the like are usually rendered water-soluble by neutralization with a basic substance. At this time, the basic substance is preferably used in an amount necessary to neutralize 40 mol% or more of the acidic groups contained in the water-soluble resin. Examples of the basic substance include ammonia, dimethylamine, trimethylamine, diethylamine, triethylamine, propylamine, triethanolamine, N-methylethanolamine, N-aminoethylethanolamine, N-methyldiethanolamine, morpholine, and monoisopropanol. Examples include amines, diisopropanolamine, dimethylethanolamine and the like.

  The number average molecular weight of the water-soluble resin is not particularly limited, but is usually preferably 500 to 50000, more preferably 800 to 25000, and particularly preferably 1000 to 12000.

  The foaming agent used in the present invention is necessary for further improving the soundproofing / vibration suppression / sound absorption performance, and a foaming agent that generates gas by heating can be used. With this generated gas, bubbles are formed inside the coating film, and inorganic fine particles are included inside the bubbles, thereby reducing the impact sound generated when pebbles and the like collide with the coating film. Specifically, for example, azo foaming agents such as azodicarbonamide and azobisformamide, nitroso foaming agents such as dinitrosopentamethylenetetramine, hydrazine foaming agents such as benzenesulfonyl hydrazide, and the like can be used. In addition, foaming aids can be used to lower the decomposition temperature of these foaming agents and promote gas generation, such as zinc oxide, lead stearate, zinc stearate, sodium-based, potassium-based compounds. Urea and the like can be used.

  The coating composition of the present invention can further contain a plasticizer and a filler. As the plasticizer, a general plasticizer suitable for the selected thermoplastic resin can be used. For example, a phthalic acid ester system, a phosphoric acid ester system, an aliphatic dibasic acid ester system, a dihydric alcohol ester system, etc. can be mentioned. In addition, mineral oil softeners combining three kinds of aromatic rings, naphthene rings, and paraffin chains, liquid or low molecular weight synthetic resin softeners, and the like can be given. Examples of the filler include powdery fillers such as calcium carbonate, barium sulfate, calcium oxide, clay and talc, scaly fillers such as mica and graphite, acicular calcium metasilicate, zonolite, potassium titanate, rock Needle-like filler such as short wool fiber, short glass fiber, aluminum silicate, short carbon fiber, short aramid fiber, inorganic hollow filler such as glass balloon, silica balloon, carbon inorganic hollow sphere, and vinylidene chloride, Examples thereof include organic hollow fillers such as plastic balloons made of an organic synthetic resin such as acrylonitrile.

  The content of the plasticizer is preferably 1 to 10% by mass and particularly preferably 3 to 5% by mass with respect to the amount of the coating film component of the coating composition. If it is less than 1% by mass, the effect may not be obtained. When it exceeds 10 mass%, it may be softened and an excellent coating film physical property may not be obtained. 5-50 mass% is preferable with respect to the coating-film component amount of a coating composition, and, as for content of a filler, 10-40 mass% is especially preferable. If it is less than 5% by mass, the hardness may decrease. If it exceeds 50% by mass, chipping resistance may be deteriorated.

  In addition to the above components, the coating composition of the present invention may contain a colorant, a high-boiling organic solvent for improving coating workability, and an adhesive for enhancing the adhesion of the coating film. it can. Examples of the colorant include carbon black and titanium oxide. Examples of the adhesive include one or more resins selected from polyamines, polyamides, polyols, and the like, and polyisocyanate prepolymers whose terminal NCO groups are blocked with an appropriate blocking agent such as oxime and lactam. Of the mixture. In addition, various known additives such as anti-aging agents, stabilizers, ultraviolet absorbers, and decomposition agents effective for thermoplastic resins can also be contained.

  As the coating method of the coating composition of the present invention, any coating method such as spray coating, brush coating, roll coater coating, bar coater coating and the like can be adopted depending on the object to be coated. However, airless spray coating is suitable for obtaining a film thickness in a short time for the purpose of painting the lower part of an automobile body. The coating composition of the present invention may be applied to a single layer or two or more layers. The baking of the coating film may be appropriately selected, but the baking temperature may be usually 120 to 180 ° C., and the baking time may be usually 1 minute to 2 hours. Although the film thickness of the coating film to be formed is not particularly limited, it may be usually 1 to 1000 μm.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention in detail, this invention is not limited to these.

[Example 1]
An ADCA (azodicarbonamide) -based foaming agent was coated on a vinyl chloride sol or an acrylic sol with tungsten particles having an average particle diameter of 0.5 to 5.0 μm and a specific gravity of 13 to 15, and samples were prepared by the method described later.

[Example 2]
ADCA (azodicarbonamide) foaming agent is coated on tungsten particles having an average particle size of 0.5 to 5.0 μm and a specific gravity of 13 to 15 in an aqueous emulsion material such as an acrylic emulsion or SBR emulsion, and a sample is prepared by the method described below. Created.

[Comparative Example 1]
Separately, the above vinyl chloride sol or acrylic sol "was sampled by the method described later without applying the foaming agent.

[Comparative Example 2]
A sample of an aqueous emulsion material such as an acrylic emulsion or an SBR emulsion was separately prepared by the method described below without applying the foaming agent.

[Evaluation results]
About the sample of an Example and a comparative example, the sound absorption property, the sound insulation property, and the damping property were investigated with the following method. The evaluation method is as follows. The results are shown in Table 1 below.
Damping property: Loss factor in the cantilever method (applied to steel plate of 10 x 220 mm and baked at 130 ° C)
Sound absorptivity: Sound absorption rate in a two-microphone sound absorption tube (applied to release paper, peeled after baking at 130 ° C., cut to φ100-φ29)
Sound insulation: Transmission loss in sound insulation measuring equipment (applied to release paper, peeled after baking at 130 ° C, cut to φ93)

As evaluation criteria, “Example 1” was evaluated against “Comparative Example 1”, and “Example 2” was evaluated against “Comparative Example 2” according to the following criteria.
◎: Increase effect by 51% or more ○: Increase effect by 21-50% △: Increase effect by 0-20% ×: Decrease effect

  From the results shown in Table 1, it can be seen that the coating composition of the present invention including the bell-shaped cell has markedly improved sound absorption, sound insulation, and vibration control compared to the case where the bell-shaped cell is not included.

  Whereas the conventional vibration damping material is to increase the weight of the material itself according to the law of mass, the resin composition and the coating composition of the present invention have excellent sound absorbing properties without increasing the weight of the material itself. Sound insulation and vibration control are exhibited. Taking advantage of these characteristics, this resin composition and coating composition are used for automotive coatings, architectural interior coatings, architectural exterior coatings, automotive adhesives, architectural adhesives, automotive structural materials, and architectural structures. It is suitably used for various applications such as materials.

The coating film formation containing the bell-shaped cell which encloses the inorganic fine particle of this invention is shown typically. The case where the coating film containing the bell-shaped cell which encloses the inorganic fine particle of this invention in the vehicle body bottom part, especially a wheel house is shown typically.

Claims (17)

  A resin composition comprising inorganic fine particles coated with a foaming agent on the surface.   2. The resin composition according to claim 1, wherein the inorganic fine particles are at least one selected from metals, metal oxides, alloys, magnetic fine particles, ceramics, and glass.   The resin composition according to claim 1 or 2, wherein the average particle diameter of the inorganic fine particles in the bell-shaped cell is 5 to 500 nm and the specific gravity is 1.0 to 5.0.   A coating composition comprising inorganic fine particles coated with a foaming agent on the surface.   The coating composition according to claim 4, wherein the inorganic fine particles are at least one selected from metals, metal oxides, alloys, magnetic fine particles, ceramics, and glass.   The coating composition according to claim 4 or 5, wherein the average particle diameter of the inorganic fine particles in the bell-shaped cell is 5 to 500 nm and the specific gravity is 1.0 to 5.0.   The coating composition according to any one of claims 4 to 6, which is a plastisol mainly composed of resin powder and a plasticizer.   The coating composition according to any one of claims 4 to 7, which is a water-based emulsion mainly composed of a water-soluble resin.   A coating film comprising a bell-shaped cell having pores inside the coating film and encapsulating inorganic fine particles capable of moving independently of the pores (cells).   The coating film according to claim 9, wherein part or all of the pores (cells) in the coating film form open cells.   The coating composition according to claim 9 or 10, wherein the average particle diameter of the inorganic fine particles in the bell-shaped cell is 5 to 500 nm and the specific gravity is 1.0 to 5.0.   The coating composition according to any one of claims 9 to 11, wherein an average particle diameter of pores (cells) serving as an outer shell of the bell-shaped cell is 5 to 500 µm.   A step of applying a coating composition containing inorganic fine particles coated with a foaming agent on the surface and a resin as a coating film component to an object, heating the obtained coating material to foam the foaming agent, and forming a coating film By this, the coating-film formation method containing the bell-shaped cell which has a void | hole inside a coating film and encloses the inorganic fine particle which can move independently of this void | hole (cell) in this void | hole.   The method of forming a coating film according to claim 13, wherein the step of heating the coated material also serves as a drying step.   A soundproof / vibration / sound absorbing paint comprising the paint composition according to claim 4.   An automobile paint comprising the paint composition according to any one of claims 4 to 8. An automobile having the coating film according to claim 9 or 10.

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