JP2016108347A - Coating composition, and self-repair type formed coating film using the composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating composition which is excellent not only in self-repairing property for scratches of the coating film but also in compatibility of the coating solution, and transparency, smoothness, and recovery limit strength of the coating film.SOLUTION: The self-repair type coating composition is obtained by reacting an organic polyisocyanate (A), an acrylic polyol (B), and a polycarbonate polyol (C), where the organic polyisocyanate (A) has a functional group number of 3.0 or more, and a number average molecular weight of the polycarbonate polyol (C) is 250 to 750.SELECTED DRAWING: None

Description

  The present invention is useful for imparting a function of self-healing of scratches on a coating film on the surface of an automobile exterior plate or plastic molded article, and further, a coating composition excellent in transparency and smoothness of the coating film, and the composition The present invention relates to the technology of self-healing-type coating films using sachets.

  Since plastic materials have excellent processability, they are molded into various shapes and widely used as a molded product in many industrial fields. However, plastic materials generally have lower hardness than glass, metal, etc., and have the disadvantage that the surface is easily scratched, so that a coating film having excellent scratch resistance is formed on the surface of the molded product. Yes.

  Conventionally, as a method of forming a coating film excellent in scratch resistance, a method of forming a coating film having a high crosslinking density and high surface hardness (hereinafter referred to as “hard coat treatment”) has been widely used. However, since this hard coat treatment has a high crosslinking density and coating film hardness, it has an advantage of greatly improving the scratch resistance, but on the other hand, the coating film tends to become brittle. For this reason, once a scratch is made, a coating film crack is generated from the site, and in some cases, the crack extends to the molded body itself.

  Or, when a plastic molded product that has been hard-coated is used as an exterior part of an automobile, sand, pebbles, etc. may collide with the surface of the molded article while the automobile is running, and scratches such as fine dents and dents on the coating surface. In order to prevent such dents with a hard-coated coating film, it is necessary to avoid the thick coating film. However, increasing the thickness of the coating film has caused problems such as a decrease in design properties due to a decrease in fine workability and an increase in the weight of exterior parts.

  In such a background, a rubber elastic coating composition (hereinafter referred to as “soft coat”) having a function of absorbing external force and restoring damage (hereinafter referred to as “self-repairing”) is known. (For example, see Patent Documents 1 to 4).

  Since the polyurethane coating composition described in Patent Document 1 and Patent Document 2 can form a flexible and tough coating film as compared with a conventional self-repairing coating composition, a coating film surface layer that forms scratches. In addition to exhibiting sufficient resistance to tearing of the fine coating film of the part, the coating film surface is excellent in scratch resistance, self-repairing property, stain resistance, and blocking resistance.

JP 2006-124610 A JP 2006-328252 A JP 2007-9219 A JP 2011-207953 A

  However, since the polyurethane paint compositions of Patent Document 1 and Patent Document 2 use polyester as a main component, when used as an exterior topcoat paint, they are inferior in water resistance and moist heat resistance, particularly in a weather resistance test. There was a possibility that the self-healing property of the wound after going through was lowered. Also, the self-repair time of the coating film was not sufficient.

  In Patent Document 3, a coating composition formed using a coating composition containing a polydimethylsiloxane copolymer, polycaprolactone, polysiloxane, or a coating composition in which a siloxane component is introduced into a skeleton is used. Although it is reported that it is excellent in the property, the self-restoring property of the coating film is not mentioned.

  Moreover, in patent document 4, it is reported that the coating film formed using the coating composition containing polycarbonate diol and a caprolactone modified acrylic polyol is excellent in abrasion resistance. However, the transparency and smoothness of the resulting coating film are insufficient, and the compatibility of the coating solution and the coating film appearance when using a polycarbonate diol having a specific molecular weight are not disclosed or disclosed.

  The present invention has been made on the basis of the circumstances as described above, and its purpose is not only self-healing property for coating film scratches, but also compatibility of coating solution, transparency of coating film, smoothness, repair limit. It is to provide a coating composition having excellent strength.

  That is, this invention is shown by the following (1)-(10).

  (1) A self-healing coating composition obtained by reacting an organic polyisocyanate (A), an acrylic polyol (B), and a polycarbonate polyol (C), wherein the organic polyisocyanate (A) is 3.0 A self-healing coating composition characterized in that it is a modified polyisocyanate having the number of functional groups described above, and the polycarbonate polyol (C) has a number average molecular weight of 250 to 750.

  (2) The self-healing as described in (1) above, wherein the organic polyisocyanate (A) is a modified polyisocyanate having a number of functional groups of 3.0 or more obtained by reaction of a polyol and an organic diisocyanate. Mold paint composition.

  (3) The self-healing paint composition as described in (2) above, wherein the polyol used as the raw material for the organic polyisocyanate (A) is at least one selected from the group consisting of polytetramethylene glycol and polycarbonate polyol. object.

  (4) The organic diisocyanate used as a raw material for the organic polyisocyanate (A) is at least one selected from the group consisting of aliphatic diisocyanates and alicyclic diisocyanates, as described in (2) or (3) above Self-healing paint composition.

  (5) The self-healing coating composition as described in (2) or (3) above, wherein the organic diisocyanate used as a raw material for the organic polyisocyanate (A) is hexamethylene diisocyanate.

  (6) The organic polyisocyanate (A) is at least one selected from the group consisting of allophanate-modified polyisocyanate and isocyanurate-modified polyisocyanate, according to any one of the above (1) to (5), Self-healing paint composition.

  (7) The glass transition point of the acrylic polyol (B) is -20 to 50 ° C, the hydroxyl value is 20 to 50 mgKOH / g, and the number average molecular weight is 6,000 to 15,000. The self-healing coating composition according to any one of (1) to (6).

  (8) The molar ratio (R) of the isocyanate group in the organic polyisocyanate (A) and the hydroxyl group in the acrylic polyol (B) and the polycarbonate polyol (C) is 0.8 to 1. 2. The self-healing coating composition according to any one of the above (1) to (7), which is blended at a ratio of 2.

  (9) The self described in any one of (1) to (8) above, wherein the acrylic polyol (B) and the polycarbonate polyol (C) are blended in a ratio of 9: 1 to 7: 3 (weight ratio). Restorable paint composition.

  (10) A self-healing-type coating film, characterized in that the self-healing type coating composition according to any one of (1) to (9) is applied onto an adherend surface to form a coating film. Forming method.

  The self-healing coating composition of the present invention and the self-healing coating film are not only self-healing with respect to scratches on the coating film, but also transparency and smoothness of the coating film that could not be achieved with conventional coating compositions, and repairing. A self-healing-type formed coating film with good limit strength can be obtained.

  Since the self-healing type coating film using this self-healing type coating composition is excellent in the above-mentioned performance, it is useful for a surface coating film of a member such as an automobile exterior plate or a plastic molded product.

  The self-healing coating composition of the present invention is a self-healing coating composition obtained by reacting an organic polyisocyanate (A), an acrylic polyol (B), and a polycarbonate polyol (C). The isocyanate (A) is a modified polyisocyanate having a functional group number of 3.0 or more, and the polycarbonate polyol (C) has a number average molecular weight of 250 to 750.

  In the present invention, it can be conventionally achieved by containing a modified polyisocyanate having a functional group number of 3.0 or more in the self-healing coating composition and by containing an acrylic polyol and a polycarbonate polyol having a specific molecular weight. The self-healing property can be developed within 60 seconds at room temperature, and the transparency and smoothness of the coating film under high humidity conditions can be improved by improving the drying property and moisture resistance.

  Here, the modified polyisocyanate having a functional group number of 3.0 or more used in the organic polyisocyanate (A) is preferably obtained by reacting a polyol with an organic diisocyanate, and is allophanate-modified polyisocyanate or isocyanurate-modified. More preferred is a polyisocyanate. By containing an allophanate group or isocyanurate group in the polyisocyanate, a flexible and tough coating film can be formed, and a coating film having both good self-healing properties and durability against wear can be obtained. In particular, by containing an allophanate group, it can be made into a liquid at room temperature, and the handling property in coating becomes good.

  In addition, in the organic polyisocyanate (A), the upper limit of the number of functional groups of the modified polyisocyanate having a functional group number of 3.0 or more is not particularly limited as long as the performance does not deteriorate. 0.0 or less is preferable, and 5.5 or less is more preferable.

<Polyol>
Specific examples of the polyol used as a raw material for the modified polyisocyanate include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1, 4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1, 3-hexanediol, 3,3-dimethylolheptane, diethylene glycol, dipropylene glycol, neopentyl glycol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, dimer acid diol, ethylene oxide of bisphenol A, Propylene oxide adduct, bis (β-hydro (Siethyl) benzene, xylylene glycol, glycerin, trimethylolpropane, pentaerythritol, polyether polyols such as polyester polyol and polytetramethylene glycol, polycarbonate polyol, acrylic polyol, polyolefin polyol, silicone polyol, fluorine polyol, castor oil A polyol containing at least two hydroxyl groups such as a polyol can be used, and can be used as appropriate alone or in combination of two or more.

  Among these polyols, polytetramethylene glycol and polycarbonate polyol are preferable from the viewpoints of heat resistance and water resistance.

<Organic polyisocyanate>
As the organic polyisocyanate used as the raw material of the modified polyisocyanate, aromatic polyisocyanate, araliphatic polyisocyanate, aliphatic polyisocyanate, and alicyclic polyisocyanate can be used. In addition, these allophanate-modified polyisocyanate, isocyanurate-modified polyisocyanate, uretdione-modified polyisocyanate, urethane-modified polyisocyanate, burette-modified polyisocyanate, uretoimine-modified polyisocyanate, acylurea-modified polyisocyanate, etc. are used in combination as long as performance does not deteriorate. You can also.

<Aromatic polyisocyanate>
Specific examples of the aromatic polyisocyanate include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 2,4-tolylene diisocyanate / 2,6-tolylene diisocyanate mixture, m-xylylene diisocyanate, p. -Xylylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate / 4,4'-diphenylmethane diisocyanate mixture, 4,4'-diphenyl ether diisocyanate, 2-nitrodiphenyl -4,4'-diisocyanate, 2,2'-diphenylpropane-4,4'-diisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, 4,4'-diphenylpropanedi Cyanate, m- phenylene diisocyanate, p- phenylene diisocyanate, naphthylene-1,4-diisocyanate, naphthylene-1,5-diisocyanate, can be mentioned 3,3'-dimethoxy-4,4'-diisocyanate.

<Aromatic aliphatic polyisocyanate>
Specific examples of the araliphatic polyisocyanate include 1,3- or 1,4-xylylene diisocyanate or a mixture thereof, 1,3- or 1,4-bis (1-isocyanato-1-methylethyl) benzene or a mixture thereof. Examples thereof include a mixture, ω, ω′-diisocyanato-1,4-diethylbenzene, and the like.

<Aliphatic polyisocyanate>
Specific examples of the aliphatic polyisocyanate include hexamethylene diisocyanate, tetramethylene diisocyanate, 2-methyl-pentane-1,5-diisocyanate, 3-methyl-pentane-1,5-diisocyanate, lysine diisocyanate, trioxyethylene diisocyanate, and the like. Can be mentioned.

<Alicyclic polyisocyanate>
Specific examples of the alicyclic polyisocyanate include isophorone diisocyanate, cyclohexyl diisocyanate, hydrogenated diphenylmethane diisocyanate, norbornane diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylene diisocyanate, hydrogenated tetramethylxylene diisocyanate and the like.

  Among the organic polyisocyanates, at least one selected from the group consisting of aliphatic polyisocyanates and alicyclic polyisocyanates is preferable from the viewpoint of weather resistance and the like, and hexamethylene diisocyanate is particularly preferable from the viewpoint of handling properties.

  Next, a specific procedure for producing a modified polyisocyanate having a functional group number of 3.0 or more will be described.

<Method for producing modified polyisocyanate>
First step: At least one polyol selected from polytetramethylene glycol and polycarbonate polyol having a number average molecular weight of 100 to 1,000 and an organic diisocyanate are charged in an amount in which an isocyanate group is excessive with respect to a hydroxyl group, and an organic solvent In the presence or absence of this, an urethanization reaction is carried out at 20 to 100 ° C. to produce an isocyanate group-terminated prepolymer I for modified polyisocyanate.

  Second step: An allophanatization catalyst is added to isocyanate group-terminated prepolymer I for modified polyisocyanate, and allophanatization is carried out at 70 to 150 ° C. until urethane groups are substantially absent by infrared spectroscopic analysis (IR analysis). Thus, an allophanate-modified isocyanate group-terminated prepolymer II for modified polyisocyanate is produced.

  Third step: The reaction is terminated by adding a reaction terminator to the allophanate-modified isocyanate group-terminated prepolymer II for modified polyisocyanate. In these 1st process-3rd processes, reaction is advanced under nitrogen gas or a dry air stream.

  Fourth step: Allophanate-modified isocyanate group-terminated prepolymer II for modified polyisocyanate is removed by thin film distillation or solvent extraction until the content of free organic diisocyanate is less than 1% by mass, and allophanate-modified modified polyisocyanate Isocyanate is produced.

  Here, as “amount of excess isocyanate group”, the molar ratio (R) between the isocyanate group in the organic diisocyanate and the hydroxyl group in the polyol is 6 to 6 in terms of R = isocyanate group / hydroxyl group. It is preferable to charge so that it may become 40, More preferably, it is preferable to charge so that it may become R = 7-30. When the amount is less than the lower limit, the target product may contain a large amount of isocyanurate-modified polyisocyanate. When the upper limit is exceeded, polyisocyanate containing a urethane group which is a precursor of allophanate-modified modified polyisocyanate increases, which may lead to a decrease in the number of functional groups and a decrease in productivity and yield.

  When the allophanate-modified polyisocyanate is produced in the presence of an organic solvent, various organic solvents that do not affect the reaction can be used.

<Organic solvent>
Specific examples of the organic solvent include aliphatic hydrocarbons such as octane, alicyclic hydrocarbons such as cyclohexane and methylcyclohexane, ketones such as methyl isobutyl ketone and cyclohexanone, esters such as butyl acetate and isobutyl acetate, Ethylene glycol ethyl ether acetate, propylene glycol monomethyl ether acetate, 3-methyl-3-methoxybutyl acetate, glycol ether esters such as ethyl-3-ethoxypropionate, ethers such as dioxane, methylene iodide, monochlorobenzene, etc. And polar aprotic solvents such as N-methylpyrrolidone, dimethylformamide, dimethylacetamide, dimethylsulfoxide, hexamethylphosphonylamide, and the like. These solvents can be used alone or in combination of two or more.

  A modified polyisocyanate modified with isocyanurate can be similarly produced by using an isocyanurate-forming catalyst.

  The production process of the allophanate-modified polyisocyanate will be described in more detail.

<First step: Step of producing isocyanate group-terminated prepolymer I for modified polyisocyanate>
The urethanization reaction temperature when producing the isocyanate group-terminated prepolymer I for modified polyisocyanate by reacting the organic polyisocyanate and the polyol is 20 to 120 ° C, preferably 50 to 100 ° C. In the urethanization reaction, a known urethanization catalyst can be used. Specifically, organic metal compounds such as dibutyltin diacetate, dibutyltin dilaurate and dioctyltin dilaurate, organic amines such as triethylenediamine and triethylamine, and salts thereof are selected and used. These catalysts can be used alone or in combination of two or more. The reaction time of the urethanization reaction varies depending on the presence or absence of the catalyst, the type, and the temperature, but is generally within 10 hours, preferably 1 to 5 hours is sufficient.

<Second step: Step of producing allophanate-modified isocyanate group-terminated prepolymer II for modified polyisocyanate>
After completion of the urethanization reaction, an allophanate reaction is performed to produce an allophanate-modified isocyanate group-terminated prepolymer II for modified polyisocyanate. At this time, the allophanatization reaction may be performed simultaneously with the urethanization reaction or after the urethanization reaction. When the urethanization reaction and the allophanatization reaction are performed simultaneously, the reaction may be performed in the presence of the allophanatization catalyst. When the allophanatization reaction is performed after the urethanization reaction, in the absence of the allophanatization catalyst, After performing the urethanization reaction for a predetermined time, an allophanatization catalyst may be added to carry out the allophanatization reaction.

<Allophanatization catalyst>
As the allophanatization catalyst used in the allophanatization reaction, it can be appropriately selected from known catalysts, and for example, a metal salt of a carboxylic acid can be used.

  Specific examples of the carboxylic acid include acetic acid, propionic acid, butyric acid, caproic acid, octylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, 2-ethylhexanoic acid and other saturated aliphatic carboxylic acids, cyclohexanecarboxylic acid, Saturated monocyclic carboxylic acids such as cyclopentanecarboxylic acid, saturated polycyclic carboxylic acids such as bicyclo (4.4.0) decane-2-carboxylic acid, mixtures of the above carboxylic acids such as naphthenic acid, oleic acid, linoleic acid , Monocarboxylic acids such as linolenic acid, soybean fatty acid, unsaturated fatty carboxylic acid such as tall oil fatty acid, aromatic aliphatic carboxylic acid such as diphenylacetic acid, aromatic carboxylic acid such as benzoic acid and toluic acid; phthalic acid, Isophthalic acid, terephthalic acid, naphthalene dicarboxylic acid, succinic acid, tartaric acid, oxalic acid, malonic acid, glutaric acid Adipic acid, pimelic acid, suberic acid, kurtaconic acid, azelaic acid, sebacic acid, 1,4-cyclohexyldicarboxylic acid, α-hydromuconic acid, β-hydromuconic acid, α-butyl-α-ethylglutaric acid, α, and polycarboxylic acids such as β-diethylsuccinic acid, maleic acid, fumaric acid, trimellitic acid, and pyromellitic acid.

  In addition, as the metal constituting the metal salt of carboxylic acid, alkali metals such as lithium, sodium and potassium, alkaline earth metals such as magnesium, calcium and barium, other typical metals such as tin and lead, manganese, iron, Examples include transition metals such as cobalt, nickel, copper, zinc, and zirconium.

  These carboxylic acid metal salts can be used alone or in combination of two or more. In addition, 0.001-0.1 mass% is preferable with respect to the total mass of a polyol and organic diisocyanate, and, as for the usage-amount of an allophanatization catalyst, 0.005-0.03 mass% is more preferable. When it is less than the lower limit, allophanate-modified polyisocyanate is not produced so much, the amount of by-product of urethane-modified polyisocyanate increases, and the number of functional groups of the resulting polyisocyanate decreases. Moreover, when exceeding an upper limit, there exists a possibility of causing the fall of storage stability.

  Here, the reaction temperature of the allophanatization reaction is preferably 70 to 150 ° C, preferably 90 to 130 ° C. When the reaction temperature is too low, allophanate-modified polyisocyanate is not formed so much, the amount of by-products of urethane-modified polyisocyanate increases, and the number of functional groups of the resulting polyisocyanate decreases. Moreover, when reaction temperature is too high, the by-product of isocyanurate modification polyisocyanate increases, and there exists a possibility of causing a self-repairing fall.

<Third step: Reaction stop step>
After the allophanatization reaction, a reaction terminator that deactivates the activity of the catalyst is added to stop the allophanate reaction. The addition timing of the reaction terminator is not particularly limited as long as it is after the allophanatization reaction, but it is preferably added quickly after the reaction is completed in order to suppress the progress of the side reaction.

<Reaction terminator>
Specific examples of the reaction terminator used here include inorganic acids such as phosphoric acid and hydrochloric acid, organic acids having a sulfonic acid group and a sulfamic acid group, and known compounds such as esters and acyl halides thereof. used. These can be used alone or in combination of two or more. Moreover, although the addition amount of a reaction terminator changes with kinds of catalyst, it is preferable to become 0.5-10 equivalent of a catalyst, and 0.8-5.0 equivalent is especially preferable. When the addition amount of the reaction terminator is small, the storage stability of the resulting allophanate-modified polyisocyanate may be lowered. Moreover, when there is too much addition amount, there exists a possibility that coloring may arise.
After completion of the reaction step, a purification step for removing free unreacted organic diisocyanate can be performed. This purification step is mainly used when producing a low viscosity type allophanate-modified polyisocyanate.

<Fourth step: Purification step>
In the purification step, free unreacted organic diisocyanate present in the reaction mixture is reduced to a residual content of 1.0% by weight or less, for example by thin film distillation at 120-140 ° C. under high vacuum of 10-100 Pa. It is preferable to remove. If the upper limit is exceeded, odor and storage stability may be reduced.

  Further, when an organic solvent is used in the reaction step, it is removed in this purification step.

  Thus, it is preferable to adjust the allophanate-modified modified polyisocyanate obtained through a series of steps so that the isocyanurate-modified polyisocyanate does not exceed 5 mol% by mole fraction. If the upper limit is exceeded, the self-repairability may be reduced.

  Moreover, the obtained modified polyisocyanate modified with allophanate can be converted into a blocked isocyanate by modifying a part of the isocyanate group with a blocking agent as post-crosslinking after the formation of the coating film.

<Blocking agent>
The blocking agent blocks the isocyanate group of the modified polyisocyanate modified with allophanate, eliminates the reaction with active hydrogen groups such as moisture and hydroxyl groups, and enables one-pack. Further, the blocked polyisocyanate is a latent curing agent that reacts with an active hydrogen group when the blocking agent is dissociated by heating and the isocyanate group is activated again.

  Specific examples of the blocking agent include phenol, lactam, active methylene, alcohol, mercaptan, acid amide, imide, amine, imidazole, urea, carbamate, imine, and oxime. And sulfite-based compounds. In particular, phenol, oxime, lactam, and imine are advantageously used.

  Here, specific examples of the blocking agent include phenol, cresol, xylenol, nitrophenol, chlorophenol, ethylphenol, p-hydroxydiphenyl, t-butylphenol, o-isopropylphenol, o-sec-butylphenol, p-nonylphenol, phenolic blocking agents such as pt-octylphenol, hydroxybenzoic acid, hydroxybenzoic acid ester, etc., lactam blocking agents such as ε-caprolactam, δ-valerolactam, γ-butyrolactam, β-propiolactam, diethyl malonate, Active methylene blocking agents such as dimethyl malonate, ethyl acetoacetate, methyl acetoacetate, acetylacetone, methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol , Isobutyl alcohol, t-butyl alcohol, n-amyl alcohol, t-amyl alcohol, lauryl alcohol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene Glycolic acid esters such as glycol monomethyl ether, benzyl alcohol, methoxymethanol, glycolic acid, methyl glycolate, ethyl glycolate, butyl glycolate, lactic acid esters such as lactic acid, methyl lactate, ethyl lactate, butyl lactate, methylol urea, methylol melamine , Diacetone alcohol, ethylene chlorohydrin, ethylene bromohydrin, 1,3-dichloro Alcohol-based blocking agents such as 2-propanol, ω-hydroperfluoroalcohol, acetocyanhydrin, butyl mercaptan, hexyl mercaptan, t-butyl mercaptan, t-dodecyl mercaptan, 2-mercaptobenzothiazole, thiophenol, methylthiophenol , Mercaptan block agents such as ethylthiophenol, acetanilide, acetanisidide, acetolide, acid amide block agents such as acrylamide, methacrylamide, acetic acid amide, stearic acid amide, benzamide, succinimide, phthalic acid imide, maleic acid imide, etc. Imide block agent, diphenylamine, phenylnaphthylamine, xylidine, N-phenylxylidine, carbazole, aniline, naphthylamine, butyl Amine-based blocking agents such as min, dibutylamine and butylphenylamine, imidazole-based blocking agents such as imidazole and 2-ethylimidazole, and urea-based blocks such as urea, thiourea, ethyleneurea, ethylenethiourea and 1,3-diphenylurea Agents, carbamate block agents such as phenyl N-phenylcarbamate and 2-oxazolidone, imine block agents such as ethyleneimine and propyleneimine, formamidoxime, acetaldoxime, acetoxime, methylethylketoxime, diacetylmonooxime, benzophenone Examples thereof include oxime blocking agents such as oxime and cyclohexanone oxime, and sulfite blocking agents such as sodium bisulfite and potassium bisulfite. These blocking agents can be used alone or in combination of two or more.

  The number average molecular weight of the allophanate-modified polyisocyanate thus obtained is 500 to 8,000, preferably 600 to 7,500, more preferably 700 to 7,000. If it is less than the lower limit, the self-healing property may be lowered, and if it exceeds the upper limit value, the chemical resistance may be lowered.

  Next, the acrylic polyol (B) used for the self-repairing coating composition of the present invention will be described. The acrylic polyol (B) used in the present invention is not particularly limited as long as the effects of the present invention are achieved. For example, at least one selected from the group consisting of acrylic esters and methacrylic esters [hereinafter referred to as “(meta)” Acrylic ester ". ] At least one selected from the group consisting of a hydroxy acrylate compound having at least one hydroxyl group in the molecule and a hydroxy methacrylate compound [hereinafter referred to as “(meth) acrylic hydroxy compound”]. And a polymerization initiator using a thermal energy, ultraviolet light, or light energy such as an electron beam, and the like, and an acrylic monomer copolymerized. These acrylic polyols (B) can be used alone or in combination of two or more.

<(Meth) acrylic acid ester>
Specific examples of (meth) acrylic acid esters include alkyl esters having 1 to 20 carbon atoms. Specific examples of such (meth) acrylate esters include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, (Meth) such as hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate Alkyl acrylates, esters of (meth) acrylic acid with cycloaliphatic alcohols such as cyclohexyl (meth) acrylate, phenyl (meth) acrylate, (meth) acrylic acid allyl esters such as benzyl (meth) acrylate Can be mentioned. Such (meth) acrylic acid ester can mention what was individual or combined 2 or more types.

<(Meth) acrylic acid hydroxy compound>
Specific examples of the (meth) acrylic acid hydroxy compound have at least one hydroxyl group in the molecule that can be a reaction point with the polyisocyanate composition. Specifically, 2-hydroxyethyl acrylate, 2 -Hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 3-hydroxy-2,2-dimethylpropyl acrylate, acrylic acid hydroxy compounds such as pentaerythritol triacrylate. Also, hydroxy methacrylate compounds such as 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, 3-hydroxy-2,2-dimethylpropyl methacrylate, pentaerythritol trimethacrylate, and the like can be given. These (meth) acrylic acid hydroxy compounds may include those singly or in combination of two or more.

<Polymerization initiator>
Examples of the polymerization initiator include a thermal polymerization initiator and a photopolymerization initiator, and are appropriately selected depending on the polymerization method.

  Specific examples of the thermal polymerization initiator include peroxydicarbonates such as di-2-ethylhexyl peroxydicarbonate, t-butylperoxybenzoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisopropyl carbonate, Peroxyesters such as t-hexylperoxyisopropyl carbonate, di (t-butylperoxy) -2-methylcyclohexane, di (t-butylperoxy) 3,3,5-trimethylcyclohexane and di (t-butylperoxy) cyclohexane Peroxyketals and the like.

  Specific examples of the photopolymerization initiator include acetophenone, methoxyacetophenone, 2,2-diethoxyacetophenone, p-dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, α-hydroxy-α, α ′. -Acetophenones such as dimethylacetophenone, 2-hydroxy-2-cyclohexylacetophenone, 2-methyl-1 [4- (methylthio) phenyl] -2-montforinopropanone-1, benzoin, benzoin methyl ether, benzoin ethyl ether Benzoin ethers such as benzoin isopropyl butyl ether, benzophenone, 2-chlorobenzophenone, p, p'-dichlorobenzophenone, N, N'-tetramethyl-4,4'-diaminobenzophenone, 4- (2-hydroxy Ketones such as ethoxy) phenyl (2-hydroxy-2-propyl) ketone, thioxanthones such as thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, phosphine oxides such as bisacylphosphine oxide and benzoylphosphine oxide And ketals such as benzyldimethyl ketal and quinones such as camphan-2,3-dione and phenanthrenequinone.

  In the present invention, the glass transition point of the acrylic polyol (B) is preferably in the range of -20 to 50 ° C. If it is less than the lower limit, self-healing property against repeated scratches and a decrease in stain resistance when used outdoors are not preferable. On the other hand, if the upper limit is exceeded, the self-repairability at low temperatures or normal temperatures may be reduced.

  Moreover, it is preferable that the hydroxyl value of acrylic polyol (B) is the range of 20-50 mgKOH / g, and the number average molecular weight is the range of 6,000-15,000. Outside this range, the self-healing property, smoothness, and chemical resistance may be reduced.

  Next, the polycarbonate polyol (C) used in the self-healing paint composition of the present invention will be described. The polycarbonate polyol (C) used in the present invention is not particularly limited as long as the effects of the present invention are achieved, but considering the compatibility with the acrylic polyol (B) and the appearance of the resulting coating film, the number average molecular weight Is preferably 250 to 750. Further, polyester polyols, polyether polyols, polyolefin polyols, silicone polyols, fluorine-based polyols, animal and plant-based polyols and the like can be used in combination as long as the effects of the present invention are not impaired. Good.

<Polycarbonate polyol>
Specific examples of the polycarbonate polyol include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5- Pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, 3,3-dimethylolheptane, diethylene glycol, dipropylene glycol, neo Pentyl glycol, diethylene glycol, dipropylene glycol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, dimer acid diol, ethylene oxide and propylene oxide adducts of bisphenol A, bis (β-hydroxyethyl) benze One or more low-molecular polyols such as xylylene glycol, glycerin, trimethylolpropane, pentaerythritol, dialkyl carbonates such as dimethyl carbonate and diethyl carbonate, alkylene carbonates such as ethylene carbonate and propylene carbonate, diphenyl carbonate, di Examples thereof include those obtained from a dealcoholization reaction or a dephenol reaction with diaryl carbonates such as naphthyl carbonate, dianthryl carbonate, diphenanthryl carbonate, diindanyl carbonate, and tetrahydronaphthyl carbonate.

<Polyester polyol>
Specific examples of polyester polyols include phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, succinic acid, tartaric acid, oxalic acid, malonic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, kurtaconic acid, and azelaic acid. , Sebacic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, 1,4-cyclohexyldicarboxylic acid, α-hydromuconic acid, β-hydromuconic acid, α-butyl-α-ethylglutaric acid, α, β- One or more kinds of dicarboxylic acids such as diethylsuccinic acid, maleic acid, fumaric acid or their anhydrides, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, , 3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6- Xanthdiol, 1,8-octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, 3,3-dimethylolheptane, diethylene glycol, dipropylene glycol, neopentyl glycol, diethylene glycol, dipropylene Glycol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, dimer acid diol, bisphenol A ethylene oxide and propylene oxide adducts, bis (β-hydroxyethyl) benzene, xylylene glycol, glycerin, tri Mention may be made of those obtained from a polycondensation reaction with one or more low molecular polyols such as methylolpropane and pentaerythritol. Also, lactone polyester polyols obtained from ring-opening polymerization of cyclic ester (so-called lactone) monomers such as ε-caprolactone, alkyl-substituted ε-caprolactone, δ-valerolactone, and alkyl-substituted δ-valerolactone can be exemplified. Furthermore, the polyester-amide polyol obtained by replacing a part of low molecular polyol with low molecular polyamines, such as hexamethylenediamine, isophoronediamine, and monoethanolamine, and low molecular amino alcohol can be mentioned.

<Polyether polyol>
As the polyether polyol, a polyether polyol having at least one oxyalkylene group selected from an oxyethylene group, an oxypropylene group, an oxytetramethylene group, and an oxycyclohexyl group in the molecular skeleton can be used. Specific examples of the polyether polyol include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5 -Pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, 3,3-dimethylolheptane, diethylene glycol, dipropylene glycol, Neopentyl glycol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, dimer acid diol, bisphenol A, bis (β-hydroxyethyl) benzene, xylylene glycol, glycerin, trimethylolpropane, pentaerythritol, etc. Low molecular polio Or compounds having 2 or more, preferably 2-3 active hydrogen groups such as low molecular weight polyamines such as ethylenediamine, propylenediamine, toluenediamine, metaphenylenediamine, diphenylmethanediamine, and xylylenediamine As an agent, polyether polyols obtained by addition polymerization of alkylene oxides such as ethylene oxide, propylene oxide and butylene oxide, alkyl glycidyl ethers such as methyl glycidyl ether, aryl glycidyl ethers such as phenyl glycidyl ether, tetrahydrofuran A polyether polyol obtained by ring-opening polymerization of a cyclic ether monomer such as

<Polyolefin polyol>
Specific examples of the polyolefin polyol include polybutadiene having two or more hydroxyl groups, hydrogenated polybutadiene, polyisoprene, hydrogenated polyisoprene and the like.

<Silicone polyol>
Specific examples of the silicone polyol include a vinyl group-containing silicone compound obtained by polymerizing γ-methacryloxypropyltrimethoxysilane and the like, and α, ω-dihydroxypolydimethylsiloxane having at least one terminal hydroxyl group in the molecule, α, Mention may be made of polysiloxanes such as ω-dihydroxypolydiphenylsiloxane.

<Fluorine-based polyol>
A specific example of the fluorine-based polyol is a linear or branched polyol obtained by a copolymerization reaction using a fluorine-containing monomer and a monomer having a hydroxy group as essential components. Here, the fluorine-containing monomer is preferably a fluoroolefin, for example, tetrafluoroethylene, chlorotrifluoroethylene, trichlorofluoroethylene, hexafluoropropylene, vinylidene fluoride, vinyl fluoride, trifluoromethyl trifluoroethylene. Is mentioned. Examples of the monomer having a hydroxyl group include hydroxyalkyl vinyl ethers such as hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether and cyclohexanediol monovinyl ether, hydroxyalkyl allyl ethers such as 2-hydroxyethyl allyl ether, and hydroxyalkyl vinyl crotonates. And monomers having a hydroxyl group such as a hydroxyl group-containing vinyl carboxylate or an allyl ester.

<Animal and plant polyols>
Specific examples of animal and plant polyols include castor oil, which is a linear or branched polyester polyol obtained by a reaction between a castor oil fatty acid and a polyol. Dehydrated castor oil, partially dehydrated castor oil partially dehydrated, and hydrogenated castor oil added with hydrogen can also be used. Other examples include silk fibroin.
Next, a specific manufacturing procedure of the self-repairing coating composition of the present invention will be described. In addition, as a manufacturing method of a self-restoring type coating composition, if there exists an effect of this invention, it will not specifically limit.

<Method for producing self-healing coating composition>
In the present invention, the method for producing a self-healing coating composition using the organic polyisocyanate (A), the acrylic polyol (B), and the polycarbonate polyol (C) is not particularly limited. Blended so that the molar ratio (R) of the isocyanate group in (A) and the hydroxyl group in acrylic polyol (B) and polycarbonate polyol (C) is 0.8 to 1.2 in terms of R = isocyanate group / hydroxyl group. It is preferable to do. When it is less than the lower limit, the hydroxyl group becomes excessive, which may cause a decrease in water resistance and heat and humidity resistance. Moreover, there exists a possibility that a crosslinking density may fall and durability and the mechanical strength of a coating film may fall. When the upper limit is exceeded, isocyanate groups become excessive, isocyanurate groups and urea groups are formed, and the flexibility of the coating film is lowered, so that self-repairability in actual use may not be obtained.

  Moreover, it is preferable to make acrylic polyol (B) excess with respect to polycarbonate polyol (C), and when self-repair performance is considered, acrylic polyol (B) and polycarbonate polyol (C) are 9: 1-7: 3. It is particularly preferable to blend in (mass ratio).

  The modified polyisocyanate modified with isocyanurate can be used as long as flexibility is not impaired. By using a modified polyisocyanate modified with isocyanurate, the glass transition point may be increased and the self-repairing property may be impaired. Therefore, the present invention is achieved by increasing the blending amount of the polycarbonate polyol in order to lower the glass transition point. The effect of can be produced.

  Various paint additives can be used in the self-healing paint composition of the present invention. The paint additive is used not only to provide leveling property and stain resistance of the coating film but also to further improve the scratch resistance while maintaining the self-repairing property. As a result, even when the coating film is thin, it is possible to achieve both self-restoration and scratch resistance in actual use.

  Examples of such additives include, for example, a dimethylpolysiloxane-acrylic block copolymer having an acrylic part containing at least one hydroxyl group, a dimethylpolysiloxane-polyether block copolymer containing a polyether part, and a polyester part. Dimethylpolysiloxane-polyester block copolymer containing dimethylpolysiloxane-polyether-polyester block copolymer containing a polyether part and a polyester part. By containing at least one hydroxyl group in the structure of the additive, the additive reacts with the polyisocyanate, and after forming the coating film, the additive bleeds out, causing problems such as contamination and reduced recoatability. Nothing will happen.

  Specific examples of the dimethylpolysiloxane-acrylic block copolymer include BYK-SILCLEAN 3700 (by Big Chemie Japan, number average molecular weight: 7600, silicon content: 1%).

  Specific examples of the dimethylpolysiloxane-polyether block copolymer include BYK-377 (manufactured by BYK Japan, number average molecular weight: 1400, silicon content: 18%), BYK-SILCLEAN 3720 (BYK Chemie Japan). Manufactured, number average molecular weight: 1100, silicon content: 17%), BYK-9200 (manufactured by Big Chemie Japan, number average molecular weight: 4600, silicon content: 36%), BYK-9201 (manufactured by Big Chemie Japan, Number average molecular weight: 4100, silicon content: 20%), BYK-9204 (by Big Chemie Japan), number average molecular weight: 5700, silicon content: 26%, BYK-9205 (by Big Chemie Japan, number average) Molecular weight: 4800, silicon content: 37%), BYK-92 6 (by Big Chemie Japan, number average molecular weight: 5400, silicon content: 34%), BYK-9210 (by Big Chemie Japan, number average molecular weight: 4200, silicon content: 14%), BYK-9111 ( BYK Chemie Japan, number average molecular weight: 4900, silicon content: 37%), BYK-9215 (BYK Chemie Japan, number average molecular weight: 4,500, silicon content: 29%), BYK-9230 (Bic Chemie Made by Japan, number average molecular weight: 6000, silicon content: 20%, BYK-9241 (by Big Chemie Japan, number average molecular weight: 6000, silicon content: 222%), BYK-9242 (by Big Chemie Japan) Manufactured, number average molecular weight: 10500, silicon content: 16%), BYK-9247 BYK Chemie Japan, number average molecular weight: 5400, silicon content: 25%), BYK-9420 (BYK Chemy Japan, number average molecular weight: 2500, silicon content: 33%), BYK-9001 (Bic Chemie Manufactured by Japan Co., Ltd., number average molecular weight: 6800, silicon content: 22%), BYK-9004 (manufactured by Big Chemie Japan, number average molecular weight: 6800, silicon content: 17%), BYK-9020 (Bic Chemie Japan Co., Ltd.) Manufactured, number average molecular weight: 10500, silicon content: 17%).

  Specific examples of the dimethylpolysiloxane-polyester block copolymer include BYK-370 (manufactured by Big Chemie Japan, number average molecular weight: 2100, silicon content: 8%).

  Specific examples of the dimethylpolysiloxane-polyether-polyester block copolymer include BYK-375 (manufactured by Big Chemie Japan, number average molecular weight: 2200, silicon content: 15%). These additives can be used alone or in combination of two or more.

  Moreover, an additive is used by mixing and stirring with organic polyisocyanate (A) at the time of coating as a compounding liquid of acrylic polyol (B) and polycarbonate polyol (C). It is also possible to react the additive and the polyisocyanate (B) in advance, and mix and stir the acrylic resin (A) during coating.

  If necessary, the self-healing coating composition of the present invention may contain, for example, an antioxidant such as 2,6-di-tert-butyl-4-methylphenol, an ultraviolet absorber, a pigment, a dye, a solvent, Additives such as a flame retardant, a hydrolysis inhibitor, a lubricant, a plasticizer, a filler, an antistatic agent, a dispersant, a catalyst, a storage stabilizer, and a thickener can be appropriately blended.

  Further, the self-healing coating composition obtained by the present invention can be applied on the surface of the adherend by a coating method such as spraying, brushing or dipping, and can form a self-healing coating film, In spray coating, which is easily affected by humidity, the effect of smooth self-repairing can be exhibited.

  Here, the adherend is not particularly limited, and is stainless steel, phosphate-treated steel, zinc steel, iron, copper, aluminum, brass, glass, acrylic resin, polycarbonate resin, polyethylene terephthalate resin, polyethylene naphthalate resin, Polybutylene phthalate resin, polystyrene resin, AS resin, ABS resin, polycarbonate-ABS resin, 6-nylon resin, 6,6-nylon resin, MXD6 nylon resin, polyvinyl chloride resin, polyvinyl alcohol resin, polyurethane resin, phenol resin, Melamine resin, polyacetal resin, chlorinated polyolefin resin, polyolefin resin, polyamide resin, polyether ether ketone resin, polyphenylene sulfide resin, NBR resin, chloroprene resin, SBR resin, SEBS resin, etc. An adherend formed of a raw material, an olefin resin such as polyethylene or polypropylene subjected to corona discharge treatment or other surface treatment, or an adherend having a base coating (coating layer that can be intermediately formed) on the adherend surface. The body can be used.

  Even if the film thickness of the self-healing-type coating film formed on the adherend surface layer is less than 20 μm, a thin film excellent in self-healing property, smoothness and drying property can be obtained. Moreover, the effect of this invention can be show | played by forming a film thickness of at least 5 micrometers on a to-be-adhered body by using a polydimethylsiloxane modified body as an additive.

  Thus, the self-healing coating composition of the present invention is excellent not only in self-healing properties but also in smoothness and drying properties, and in particular, a coating film having high self-healing properties in a thin film of less than 20 μm can be obtained. It is suitably used for automotive exterior materials and plastic coatings that require fine workability, high design, and weight reduction of exterior parts.

  Examples of the present invention will be described below, but the present invention is not construed as being limited to these examples.

<Synthesis of modified polyisocyanate>
<Synthesis Example 1>
Hexamethylene diisocyanate (manufactured by Tosoh Corporation, NCO content: 49.9% by mass, hereinafter referred to as “HDI”) was added to a four-necked flask having a capacity of 1,000 ml equipped with a stirrer, a thermometer, a condenser, and a dropping funnel. 700 g, PTMG-250 (manufactured by Hodogaya Chemical Co., Ltd., PTG-250): 300 g of polytetramethylene glycol and number average molecular weight 250 were charged, and urethanization reaction was performed at 80 ° C. for 2 hours in a nitrogen stream. Thereafter, 0.05 g of zirconium octylate (trade name: zirconyl octylate, manufactured by Daiichi Rare Element Chemical Industries, Ltd., hereinafter referred to as “OctZr”) was added, and an allophanatization reaction was performed at 110 ° C. for 2 hours. After the NCO content reached 40.3% by mass, 0.11 g of JP-508 (manufactured by Johoku Chemical Industry Co., Ltd., acidic phosphate ester) was added to perform a stop reaction, and the reaction solution was cooled to room temperature.

  This reaction solution was subjected to thin-film distillation at 130 ° C. × 0.04 kPa to remove unreacted HDI, and purified allophanate-modified polyisocyanate P1 was obtained.

  Allophanate-modified polyisocyanate P1 has an NCO content of 16.4% by mass, an external appearance of a transparent liquid, a number average molecular weight of 2,000, and an average functional group number calculated from the NCO content and the number average molecular weight of 5.0, 25 ° C. The viscosity was 2,000 mPa · s, and the free HDI content was 0.2% by mass.

<GPC: Measurement of molecular weight>
-Measuring instrument: "HLC-8120" (manufactured by Tosoh Corporation)
Column: “TSKguardcolumn HXL-L” (manufactured by Tosoh Corporation)
Particle size = 6 μm, Size = 6 mm ID × 30 cm × 4 carrier Carrier: Tetrahydrofuran (THF)
-Detector: Parallax refraction-Sample: 0.1% THF solution-Calibration curve: Polystyrene.

  Each raw material in the table is as follows.

AP-A: NX113-002 manufactured by Asia Kogyo Co., Ltd., Tg 30 ° C.
AP-B: DIC Corporation Acridic A-801
AP-C: ACDICIC ZHP-108 manufactured by DIC, Tg19 ° C
AP-D: DIC's ACRICID ZHP-972, Tg 21 ° C
PCP-A: 1,6-hexanediol / 3-methyl-1,5-pentanediol-based polycarbonate polyol, number average molecular weight 500
PCP-B: 1,6-hexanediol / polycaprolactone-based polycarbonate polyol, number average molecular weight 500
PCP-C: 1,6-hexanediol polycarbonate polyol, number average molecular weight 500
PCP-D: 1,6-hexanediol polycarbonate polyol, number average molecular weight 600
PCP-E: 1,6-hexanediol polycarbonate polyol, number average molecular weight 700
PCP-F: 1,6-hexanediol / 3-methyl-1,5-pentanediol-based polycarbonate polyol, number average molecular weight 1000
PCP-G: 1,6-hexanediol / 3-methyl-1,5-pentanediol-based polycarbonate polyol, number average molecular weight 2000
PCP-H: 1,6-hexanediol / 3-methyl-1,5-pentanediol-based polycarbonate polyol, number average molecular weight 3000
PCP-I: 1,6-hexanediol / polycaprolactone-based polycarbonate polyol, number average molecular weight 1000
PCP-J: 1,6-hexanediol / polycaprolactone-based polycarbonate polyol, number average molecular weight 2000
PCP-K: 1,6-hexanediol / polycaprolactone-based polycarbonate polyol, number average molecular weight 3000
PCP-L: 1,6-hexanediol polycarbonate polyol, number average molecular weight 800
PCP-M: 1,6-hexanediol polycarbonate polyol, number average molecular weight 900
PCP-N: 1,6-hexanediol polycarbonate polyol, number average molecular weight 1000
PCP-O: 1,6-hexanediol polycarbonate polyol, number average molecular weight 2000.

<Adjustment of paint>
As shown in Tables 1 to 3, the obtained modified organic polyisocyanate was mixed with acrylic polyol, polycarbonate polyol, BYK-SILCLEAN 3700 as an additive, U-CAT SA102 as a catalyst, and ethyl acetate as a diluting solvent. Adjusted.

<Coating conditions for self-healing evaluation>
・ Coating method: Use applicator ・ Humidity condition: 50% RH
・ Temperature condition: 23 ℃
・ Substrate: Acrylic resin (Kuraray Co., Ltd., 2mm thickness)
-Drying conditions: Forced drying at 80 ° C for 5 hours
-Film thickness: about 20 μm.

<Coating conditions for repair limit strength evaluation>
・ Coating method: Uses poly dropper ・ Humidity condition: 50% RH
・ Temperature condition: 23 ℃
・ Substrate: Acrylic resin (Kuraray Co., Ltd., 2mm thickness)
Drying condition: forced drying at 80 ° C. for 5 hours Film thickness: about 150 μm

  As shown in Tables 1 to 3, the self-healing coating film using the polycarbonate polyol having a number average molecular weight of 250 to 750 has excellent self-healing properties and is excellent in transparency and smoothness of the coating film. I found out.

(1) Evaluation test 1:
<Self-healing>
The obtained coating film was rubbed with a brass wire brush in an environment of a temperature of 23 ° C. and 50% RH, and the time for self-repair of scratches formed on the coating film surface was measured.

<Evaluation criteria>
・ Scars are repaired in less than 60 seconds: Pass ・ 60 seconds or more, or tearing of the coating film occurs: Fail (2) Evaluation test 2:
<Repair limit strength>
The obtained coating film was damaged by changing the weight of the weight placed on the thumbtack in an environment of 23 ° C. and 50% RH, and the maximum load that could be restored within 60 seconds was evaluated.

(3) Evaluation test 3:
<Appearance of paint mixture>
The appearance of the prepared paint blending liquid was observed.

<Evaluation criteria>
-Paint blending solution is clear: Pass-Turbidity is observed in paint blending solution: Fail (4) Evaluation test 4:
<Appearance of coating film>
The appearance of the obtained coating film was observed.

<Evaluation criteria>
-The coating film is smooth and transparent: Pass-The coating film is uneven or cracked, or turbidity is observed: Fail.

Claims (10)

A self-healing coating composition obtained by reacting an organic polyisocyanate (A), an acrylic polyol (B), and a polycarbonate polyol (C), wherein the organic polyisocyanate (A) has a functionality of 3.0 or more. A self-healing coating composition, which is a modified polyisocyanate having a group number, and wherein the polycarbonate polyol (C) has a number average molecular weight of 250 to 750. 2. The self-healing paint composition according to claim 1, wherein the organic polyisocyanate (A) is a modified polyisocyanate having a functional group number of 3.0 or more obtained by a reaction between a polyol and an organic diisocyanate. . The polyol used as a raw material for the organic polyisocyanate (A) is at least one selected from the group consisting of polytetramethylene glycol and polycarbonate polyol. The organic diisocyanate used as a raw material for the organic polyisocyanate (A) is at least one selected from the group consisting of an aliphatic diisocyanate and an alicyclic diisocyanate. . 4. The self-healing coating composition according to claim 2, wherein the organic diisocyanate used as a raw material for the organic polyisocyanate (A) is hexamethylene diisocyanate. The organic polyisocyanate (A) is at least one selected from the group consisting of allophanate-modified polyisocyanate and isocyanurate-modified polyisocyanate, 6. Self-healing paint composition according to any one of claims 1 to 5 . The glass transition point of the acrylic polyol (B) is -20 to 50 ° C, the hydroxyl value is 20 to 50 mgKOH / g, and the number average molecular weight is 6,000 to 15,000. The self-healing paint composition according to any one of 1 to 6. The molar ratio (R) of the isocyanate group in the organic polyisocyanate (A) and the hydroxyl group in the acrylic polyol (B) and the polycarbonate polyol (C) is a ratio of 0.8 to 1.2 in terms of R = isocyanate group / hydroxyl group. The self-healing paint composition according to any one of claims 1 to 7, wherein the self-healing paint composition is blended. The self-healing paint composition according to any one of claims 1 to 8, wherein the acrylic polyol (B) and the polycarbonate polyol (C) are blended in a ratio of 9: 1 to 7: 3 (mass ratio). object. A method for forming a self-healing type coating film, which comprises applying the self-healing coating composition according to any one of claims 1 to 9 onto an adherend surface to form a coating film.