Resin composition for gel coat

Abstract

To provide a resin composition for gel coat that has excellent moldability and can form a gel coat such as an FRP molding with excellent water resistance as well as excellent excoriation resistance.SOLUTION: A resin composition for gel coat contains (A) an unsaturated polyester or vinyl ester, (B) a (meth)acrylic monomer having three or more polymerizable unsaturated groups, (C) a polyrotaxane having a polymerizable unsaturated group, and (D) an unsaturated monomer having one or two polymerizable unsaturated groups.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a resin composition for gel coat used for improving the surface properties of various molded articles.

Background Art

[0002] Gel coat is a resin layer formed as the surface outer layer of various molded articles, and in addition to excellent designability and moldability, it has chemical, physical, mechanical, and electrical properties, so it is used in various applications. Its main applications include water-related equipment such as bathtubs, unit baths, wash counters, and kitchen counters, and outdoor-use products such as ships, tanks, vehicles, and domes.

[0003] Generally, unsaturated polyester resins are used as the main component of the resin composition for gel coat. However, in unsaturated polyester resins, the surface hardness of the gel coat is only about H to 2H in terms of pencil hardness, so sufficient surface hardness cannot be obtained, and there is a problem of inferior scratch resistance. Therefore, when rubbed with a hard object, it was easily scratched and its aesthetic appearance was sometimes impaired.

[0004] In order to improve scratch resistance, Patent Document 1 discloses a (meth)acrylic gel coat mainly composed of a (meth)acrylic polymer and a (meth)acrylic monomer. However, in actual FRP molded articles and artificial marble molded articles, the shape is complex, and there are problems such as film-forming properties and crack resistance during molding.

[0005] Patent Document 2 discloses a curable solvent-based clear paint composed of a lipophilic polyrotaxane having a cyclic molecule, a linear molecule that clathrates the cyclic molecule, and blocking groups arranged at both ends of the linear molecule, and the linear molecule and the cyclic molecule having hydrophobic modifying groups. However, in bathtubs and wash counters, which are the main applications of molded articles using gel coat, long-term durability is required under severe usage conditions, so there are problems of abrasion resistance and peeling.

[0006] Patent Document 3 discloses a colored plastic for automobiles by using a polyrotaxane compound. However, there was a problem that the scratch resistance could not be improved only by adding it to a general gel coat resin composition.

[0007] Patent Document 4 discloses a coating film containing a polyrotaxane compound, a polymerizable monomer, a perfluoropolyether-modified acrylate, and a polymerization initiator. However, in water-related products such as bathtubs and washbasin counters, which are the main uses of gel coats, there were problems such as peeling, abrasion resistance, cracking, hot water resistance, and chemical resistance under severe usage conditions.

[0008] Patent Document 5 discloses an unsaturated polyester resin composition using a polyrotaxane compound and a monomer having at least one of a specific hydroxyl group and an ether group. However, hot water resistance and chemical resistance were not considered, and there were problems in applying it to water-related products such as bathtubs and tanks that require chemical resistance.

[0009] Thus, even if the scratch resistance could be improved with the resin compositions for gel coats disclosed in these patent documents, the water resistance and the like were insufficient, and the basic properties required for gel coats such as fiber-reinforced plastic (FRP) moldings could not be sufficiently achieved.

Prior Art Documents

Patent Documents

[0010]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0011] An object of the present invention is to provide a resin composition for gel coat having good moldability capable of producing a gel coat such as an FRP molded product excellent in scratch resistance and water resistance.

Means for Solving the Problems

[0012] As a result of intensive studies to solve the above-described problems, the present inventors have found that a gel coat that can sufficiently satisfy various physical properties such as scratch resistance and water resistance and workability can be obtained by using a (meth)acrylic polyfunctional monomer having three or more polymerizable unsaturated groups and a polyrotaxane compound in combination with an unsaturated polyester resin, and have completed the present invention.

[0013] That is, the present invention relates to (A) Unsaturated polyester or vinyl ester, (B) A (meth)acrylic monomer having three or more polymerizable unsaturated groups, (C) A polyrotaxane having a polymerizable unsaturated group, and (D) An unsaturated monomer having one or two polymerizable unsaturated groups and relates to a resin composition for gel coat containing the same.

[0014] (A) 20 to 45% by weight of unsaturated polyester or vinyl ester, (B) 15 to 45% by weight of (meth)acrylic monomer, (C) 0.8 to 5% by weight of polyrotaxane, and (D) 20 to 50% by weight of unsaturated monomer It is preferably contained.

[0015] (B) The (meth)acrylic monomer is preferably at least one selected from trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ethylene glycol di(meth)acrylate, and alkoxy-modified products thereof.

[0016] (C) The polyrotaxane preferably has a (meth)acryloyl group.

[0017] The present invention also relates to a paint containing the resin composition for gel coat.

[0018] Furthermore, the present invention relates to a fiber-reinforced plastic molded article having a layer made of a cured product of the resin composition for gel coat.

Effects of the Invention

[0019] According to the resin composition for gel coat of the present invention, a gel coat having sufficient scratch resistance, durability, surface hardness, and excellent surface appearance and decorativeness can be provided.

Modes for Carrying Out the Invention

[0020] Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to the embodiments shown below.

[0021] The resin composition for gel coat of the present invention is characterized by containing (A) an unsaturated polyester or vinyl ester, (B) a (meth)acrylic monomer having three or more polymerizable unsaturated groups, (C) a polyrotaxane having a polymerizable unsaturated group, and (D) an unsaturated monomer having one or two polymerizable unsaturated groups.

[0022] <(A) Unsaturated polyester or vinyl ester> [Unsaturated polyester] (A) The unsaturated polyester is not particularly limited, and examples thereof include those obtained by the reaction of an α,β-unsaturated dicarboxylic acid and a polyhydric alcohol. Examples of the α,β-unsaturated dicarboxylic acid include fumaric acid, maleic acid, maleic anhydride, itaconic acid, citraconic acid, mesaconic acid, chloromaleic acid, het acid, or dimethyl esters thereof. These α,β-unsaturated carboxylic acids may be used alone or in combination of two or more. Among these, fumaric acid, or maleic acid and its anhydride are generally preferred from the viewpoints of reactivity and various physical properties of the cured product.

[0023] In addition to the α,β-unsaturated dicarboxylic acid, a saturated dicarboxylic acid can be used in combination as needed. Examples of the saturated dicarboxylic acid include phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, adipic acid, sebacic acid, azelaic acid, tetrabromophthalic anhydride, etc. These saturated dicarboxylic acids may be used alone or in combination of two or more.

[0024] Examples of the polyhydric alcohol include diols such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, trimethylene glycol, triethylene glycol, 1,3-butanediol, 1,4-butanediol, 2-methyl-1,3-propanediol, 1,6-hexanediol, cyclohexanediol, neopentyl glycol, 2,2,4-trimethyl-1,3-pentanediol, 1,4-cyclohexanedimethanol, hydrogenated bisphenol A, and hydrogenated bisphenol A·alkylene oxide adducts; triols such as trimethylolpropane; and tetraols such as pentaerythritol. These polyhydric alcohols may be used alone or in combination of two or more. Among these, from the viewpoints of various physical properties such as chemical resistance, it is preferable to use propylene glycol or neopentyl glycol.

[0025] In order to impart air-dryability to the resin as necessary, allyl ethers such as ethylene glycol monoallyl ether, diethylene glycol monoallyl ether, triethylene glycol monoallyl ether, polyethylene glycol monoallyl ether, propylene glycol monoallyl ether, dipropylene glycol monoallyl ether, tripropylene glycol monoallyl ether, polypropylene glycol monoallyl ether, 1,2-butylene glycol monoallyl ether, 1,3-butylene glycol monoallyl ether, hexylene glycol monoallyl ether, octylene glycol monoallyl ether, trimethylolpropane diallyl ether, glycerin diallyl ether, etc. can also be used.

[0026] Furthermore, by selectively using halides such as brominated saturated dicarboxylic acids, dibromoneopentyl glycol, brominated glycol, etc., flame retardant performance can be imparted to the resulting resin composition.

[0027] Furthermore, those obtained by reacting a carboxy group or a hydroxy group at the molecular terminal of the obtained unsaturated polyester resin with an α,β-unsaturated carboxylic acid ester having an epoxy group or a (meth)acrylate having a hydroxy group can also be used. Also, a modified unsaturated polyester resin obtained by reacting a polyisocyanate with the hydroxy group at the molecular terminal of the unsaturated polyester resin can be used. In this specification, “(meth)acrylate” means that both acrylate and methacrylate are included, and “(meth)acrylic” means that both acrylic and methacrylic are included.

[0028] Also, dicyclopentadiene may be added and reacted with the above α,β-unsaturated dicarboxylic acid and polyhydric alcohol to obtain a dicyclopentadiene-based unsaturated polyester.

[0029] [Vinyl ester] The vinyl ester (A) used in the present invention is not particularly limited, and examples thereof include reaction products obtained by reacting an epoxy resin with an unsaturated monobasic acid.

[0030] Examples of the epoxy resin include, as glycidyl ethers of phenols, bisphenol type epoxy resins such as bisphenol A type epoxy resin and bisphenol F type epoxy resin, and brominated resins thereof, phenol novolac type epoxy resin and brominated resins thereof, cresol novolac type epoxy resins, dipropylene glycol diglycidyl ether, trimethylolpropane triglycidyl ether, diglycidyl ethers of alkylene oxide adducts of bisphenol A, glycidyl ethers of polyhydric alcohols such as hydrogenated bisphenol A glycidyl ether, alicyclic epoxy resins such as 3,4-epoxy-6-methylcyclohexylmethyl-3,4-epoxy-6-methylcyclohexanecarboxylate and 1-epoxyethyl-3,4-epoxycyclohexane, glycidyl esters such as diglycidyl phthalate, diglycidyl tetrahydrophthalate, diglycidyl-p-oxybenzoic acid, and dimer acid glycidyl ester, glycidyl amines such as tetraglycidyl diaminodiphenylmethane, tetraglycidyl-m-xylenediamine, triglycidyl-p-aminophenol, and N,N-diglycidylaniline, and heterocyclic epoxy resins such as 1,3-diglycidyl-5,5-dimethylhydantoin and triglycidyl isocyanurate. These epoxy resins may be used alone or in combination of two or more.

[0031] Examples of the unsaturated monobasic acid include acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, acrylic acid dimer, monomethyl maleate, monomethyl fumarate, monocyclohexyl fumarate, or sorbic acid. These acids may be used alone or in combination of two or more.

[0032] Furthermore, the obtained vinyl ester resin may be modified with acid anhydrides such as maleic anhydride and succinic anhydride, isocyanate compounds such as toluene diisocyanate and isopropenyl-dimethyl-benzyl isocyanate, and the like.

[0033] (A) The unsaturated polyester or vinyl ester is preferably contained in the gel coat resin composition in an amount of 20 to 45% by weight, more preferably 25 to 35% by weight. If it is less than 20% by weight, problems are likely to occur from the viewpoints of curing and drying properties and film-forming properties. If it exceeds 45% by weight, the characteristics of the present invention such as scratch resistance tend not to be obtained.

[0034] <(B) (Meth)acrylic monomer having three or more polymerizable unsaturated groups> (B) The (meth)acrylic monomer is not particularly limited, and trifunctional (meth)acrylic monomers such as trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, trimethylolpropane EO-modified tri(meth)acrylate, isocyanuric acid EO-modified tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, propoxylated glyceryl tri(meth)acrylate, and trifunctional polyester (meth)acrylate; tetrafunctional or higher (meth)acrylic monomers such as pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, dipentaerythritol tetraacrylate, dipentaerythritol hydroxypenta(meth)acrylate, and dipentaerythritol hexaacrylate, etc. may be mentioned. These (meth)acrylic monomers may be used alone or in combination of two or more. Among these, from the viewpoints of water resistance and hardness improvement, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and their alkoxy-modified products are preferred. The upper limit of the number of polymerizable unsaturated groups is preferably 10 or less, more preferably 6 or less.

[0035] In addition, a bifunctional allyl monomer such as diallyl phthalate may be used in combination with the (B) (meth)acrylic monomer.

[0036] (B) The (meth)acrylic monomer is preferably contained in the gel coat resin composition in an amount of 15 to 40% by weight, more preferably 20 to 30% by weight. If it is less than 15% by weight, the effect of improving scratch resistance becomes low, and if it exceeds 40% by weight, there tends to be a problem in molding workability due to becoming physically hard or the influence of the anaerobic property of the acrylic monomer.

[0037] <(C) Polyrotaxane having a polymerizable unsaturated group> (C) In the polyrotaxane, a linear molecule penetrates through the opening of a cyclic molecule in a skewer-like manner, and blocking groups are arranged at both ends of the linear molecule so that the cyclic molecule does not detach. Further, the cyclic molecule is a compound having at least one polymerizable unsaturated group.

[0038] Examples of the polymerizable unsaturated group include a vinyl group and a (meth)acryloyl group. Among them, from the viewpoint of the curing reactivity of the obtained cured product, a (meth)acryloyl group is preferable. The (meth)acrylic equivalent representing the number of polymerizable unsaturated groups is preferably 500 to 5,000 g / eq.

[0039] Examples of the cyclic molecule include cyclodextrin,, crown ether, benzo crown, dibenzo crown, dicyclohexano crown, and derivatives or modified products thereof. From the viewpoint of the inclusion ability of the linear molecular chain, the cyclic molecule is preferably cyclodextrin or a derivative or modified product thereof. Examples include crown ether, benzo crown, dibenzo crown, dicyclohexano crown, and derivatives or modified products thereof. On the other hand, examples of the linear molecule include a polyalkylene chain, a polyester chain, a polyether chain, a polyamide chain, and a polyacrylate chain. Among them, a polyethylene glycol chain of a polyether chain is preferable in terms of good penetrability into the cyclic molecule and excellent effects being obtained. Examples of the blocking group include an adamantyl group, a group containing cyclodextrin, an anthracene group, a triphenylene group, a pyrene group, a trityl group, and isomers and derivatives thereof.

[0040] (C) The weight average molecular weight Mw of the entire polyrotaxane having a polymerizable unsaturated group is preferably 100,000 to 1,000,000, and more preferably 150,000 to 500,000. Also, the weight average molecular weight Mw of the polymer serving as the axis of the polyrotaxane is preferably 5,000 to 50,000, and more preferably 10,000 to 30,000.

[0041] (C) As the polyrotaxane, commercially available products can be used. For example, the Celm Super Polymer SM / SA series manufactured by Advance Soft Materials Co., Ltd. can be mentioned. The polyrotaxane may be used alone or in combination of two or more kinds.

[0042] (C) The polyrotaxane is preferably contained in the resin composition for the gel coat at 0.5 to 5% by weight, more preferably 1 to 3% by weight. If it is less than 0.5% by weight, the crack suppressing effect cannot be obtained, and if it exceeds 5% by weight, the scratch resistance required tends not to be obtained due to the influence of the polyrotaxane.

[0043] <(D) Unsaturated monomer having one or two polymerizable unsaturated groups> (D) The unsaturated monomer is not particularly limited, and examples thereof include styrene-based monomers and (meth)acrylic acid-based monomers. These unsaturated monomers may be used alone or in combination of two or more kinds.

[0044] Examples of the styrene-based monomer include styrene, p-methylstyrene, t-butylstyrene, chlorostyrene, vinylbenzyl alkyl ether, and the like. Among these, styrene is preferable from the viewpoints of cost and physical properties of the cured product.

[0045] In addition, examples of the (meth)acrylic acid-based monomer include, as a monomer having one polymerizable unsaturated group, (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate and other (meth)acrylic acid alkyl esters, cyclohexyl (meth)acrylate and other (meth)acrylic acid cycloalkyl esters, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate and other basic (meth)acrylic acid esters. Further, examples of the monomer having two polymerizable unsaturated groups include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate. Among these, from the viewpoints of viscosity reduction effect and curing reactivity, a monomer having one polymerizable unsaturated group is preferable, and methyl (meth)acrylate is preferable.

[0046] (D) The unsaturated monomer is preferably contained in the resin composition for gel coat in an amount of 25 to 50% by weight, more preferably 30 to 45% by weight. If it is less than 25% by weight, the viscosity is high and the workability is affected, and if it exceeds 50% by weight, it tends to be impossible to obtain the physical properties of the present invention from the viewpoints of curability and physical properties. The (D) unsaturated monomer may be supplied in a form previously contained in the (A) unsaturated polyester or vinyl ester.

[0047] Considering coating workability such as defoaming and leveling, it is preferable to adjust the viscosity of the resin composition for gel coat to be 100 to 160 mPas with a B-type viscometer.

[0048] <Other components> A curing agent (curing catalyst), a curing accelerator, a thixotropic agent, a thixotropy aid, an antifoaming agent, a pigment, an ultraviolet absorber, an ultraviolet stabilizer and the like may be added to the resin composition for gel coat of the present invention.

[0049] The curing agent is not particularly limited, and examples thereof include organic peroxide-based curing agents such as diacyl peroxide-based, peroxyester-based, hydroperoxide-based, dialkyl peroxide-based, ketone peroxide-based, peroxyketal-based, alkyl perester-based, and percarbonate-based curing agents.

[0050] More specifically, for example, methyl ethyl ketone peroxide, cyclohexane peroxide, acetylacetone peroxide, acetoacetic acid ester peroxide, benzoyl peroxide, t-butyl peroxy-2-ethylhexanoate, t-amyl peroxy-2-ethylhexanoate, t-butyl peroxypivalate, t-butyl peroxyisobutyrate, lauryl peroxide, etc. can be mentioned. These curing agents may be used alone or in combination of two or more.

[0051] The addition amount of the curing agent is preferably 0.5 to 5 parts by weight, more preferably 0.7 to 3 parts by weight, based on 100 parts by weight of the unsaturated polyester or vinyl ester (A).

[0052] The curing accelerator is not particularly limited, and specifically, for example, metal soaps (higher fatty acid metal salts) such as cobalt naphthenate, cobalt octylate, divalent cobalt acetylacetonate, trivalent cobalt acetylacetonate, potassium hexoate, zirconium octenoate, cobalt octenoate, zirconium acetylacetonate, vanadium naphthenate, vanadium octylate, vanadium acetylacetonate, vanadium acetylacetonate oxide, lithium acetylacetonate; amines such as dimethylaniline and diethylaniline; phosphorus-containing compounds; β-diketones, etc. can be mentioned. Among them, cobalt octenoate or cobalt octylate is preferable. These may be used alone or in combination of two or more.

[0053] The addition amount of the hardening accelerator is preferably 0.01 to 5 parts by weight, more preferably 0.1 to 1 part by weight, based on 100 parts by weight of the unsaturated polyester or vinyl ester (A). The hardening accelerator may be added in advance to the unsaturated polyester or vinyl ester (A), or may be added immediately before adding the hardening agent.

[0054] The thixotropic agent is not particularly limited as long as it can impart the required viscosity and thixotropy to the gel coat resin composition. Specifically, for example, silica powder, talc powder, mica powder, glass flakes, metal whiskers, ceramic whiskers, calcium sulfate whiskers, smectite, organic thixotropic agents, etc. can be mentioned.

[0055] Commercially available products of thixotropic agents include fumed silica: Rheolex QS series (manufactured by Tokuyama Corporation), Aerosil series (manufactured by Nippon Aerosil Co., Ltd.), BENATHIX series (manufactured by Cornell Brothers Japan Co., Ltd.), CLAYTONE series (manufactured by BYK-Chemie Japan Co., Ltd.), talc MS, ML series (manufactured by Fuji Talc Industry Co., Ltd.), etc.

[0056] The addition amount of the thixotropic agent depends on the shape of the object to which the gel coat is applied, particularly the height, area, and shape of the vertical surface, the thickness of the gel coat to be applied, the ambient temperature, and the properties of the resin composition or the resin (polymer) contained in the resin composition. However, it can be defined by the viscosity required for the gel coat resin composition. The viscosity of the resin composition is preferably 0.5 to 3 Pa·s, more preferably 1.0 to 2.7 Pa·s, and even more preferably 1.5 to 2.5 Pa·s. Also, it is preferably added in an amount such that the thixotropy (viscosity ratio between 6 rpm and 60 rpm) is 4.0 to 7.0. Here, the viscosity can be measured under the conditions of a BM type viscometer, No. 4 rotor, 25°C, and 60 rpm.

[0057] The thixotropy aid depends on the properties of the gel coat resin composition. By adding it, the addition amount of the above thixotropic agent can be reduced, and various physical properties of the resin composition can be improved.

[0058] Examples of the thixotropy aid include, but are not particularly limited to, glycols such as ethylene glycol, polyethylene glycol, and polypropylene glycol; monofunctional or polyfunctional (meth)acrylates having a hydroxyl group and / or an ether bond (excluding those corresponding to component (B)); epoxy ethers having a hydroxyl group and / or an ether bond; epoxy esters having a hydroxyl group and / or an ether bond; surfactants such as polyoxyethylene sorbitan monolaurate. Two or more of these may be used in combination.

[0059] In addition, various thixotropy increasing agents, stabilizers, etc. can also be used as the thixotropy aid. Commercially available products of thixotropy increasing agents and stabilizers include, for example, BYK R605, BYK410 (manufactured by BYK-Chemie Japan Co., Ltd.), etc.

[0060] The addition amount of each thixotropy aid depends on the properties of the resin composition for gel coat and the type of thixotropy aid, but is preferably 0.001 to 5 parts by weight, more preferably 0.01 to 3 parts by weight, based on 100 parts by weight of (A) unsaturated polyester or vinyl ester.

[0061] The defoaming agent is not particularly limited. For example, non-silicone defoaming polymer solutions (non-silicone defoaming agents) such as BYK A-515, BYK A-555, BYK A-501 (manufactured by BYK-Chemie Japan Co., Ltd.), and EFFKA 2720 (manufactured by BASF); silicone defoaming agents such as Disparon AP series, OX series, and L series (manufactured by Kusumoto Chemical Co., Ltd.); SH series (manufactured by Shin-Etsu Chemical Co., Ltd.), etc. The addition amount of the defoaming agent is preferably 0.001 to 2.0 parts by weight based on 100 parts by weight of (A) unsaturated polyester or vinyl ester.

[0062] The pigment is appropriately selected for purposes such as improving the decorativeness, aesthetic appearance, or weather resistance of the gel coat, and is not particularly limited. Specifically, for example, titanium oxide white, iron oxide red, iron hydroxide yellow, condensed azo red, DPP red, titanium yellow, cobalt blue, quinacridone red, carbon black, iron black, perinone, isoindolinone, chrome green, cyanine blue, cyanine green, etc., which are generally used for coloring purposes, can be mentioned. Also, the addition amount thereof is not particularly limited.

[0063] The addition amount of the pigment varies depending on the color tone, but (A) 1 to 30 parts by weight, preferably 3 to 15 parts by weight, is preferable with respect to 100 parts by weight of the unsaturated polyester or vinyl ester.

[0064] The ultraviolet absorber and ultraviolet stabilizer are appropriately selected for the purpose of improving weather resistance and are not particularly limited. Examples of the ultraviolet absorber include benzophenone-based compounds, benzotriazole-based compounds, and cyanoacrylate-based compounds, and examples of the ultraviolet stabilizer include hindered amine-based compounds.

[0065] In addition, if necessary, a curing acceleration auxiliary agent, a curing time adjuster, a reinforcing material, a filler, a modifier, a flame retardant, etc. may be added. These additives are appropriately selected according to the purpose of use of the gel coat, and the type and specific compound thereof are not particularly limited.

[0066] Further, the paint of the present invention is characterized by containing the resin composition for gel coat.

[0067] The gel coat is a resin layer formed as the surface outer layer of various molded articles. Specific applications include, for example, applications where the decorative and aesthetic properties of bathtubs, ships, tanks, vehicles, FRP moldings, artificial marble, and cast article surfaces are emphasized. In applications such as bathtubs, ships, tanks, and vehicles, since they are exposed to warm water or outdoors and come into contact with various substances, the gel coat itself is required to have durable properties. Specifically, heat resistance, hot water resistance, water resistance, chemical resistance, or weather resistance, etc. can be mentioned, and the resin composition for gel coat of the present invention can be preferably applied.

[0068] In applications such as FRP moldings and artificial marble cast articles, since a film is formed by coating the mold in advance during manufacturing, it becomes the outermost layer of the molded article, and aesthetic and durability are required. Specifically, the finish such as the gel coat curing uniformly, no air bubbles remaining, no sagging or unevenness occurring, and no cracks or unevenness occurring, etc. can be mentioned, and the resin composition for gel coat of the present invention can be preferably applied.

[0069] In applications where the decorative and aesthetic properties of the surface are emphasized, it is required to function so that scratches, etc. are not easily formed on the surface. Specifically, sufficient surface hardness can be mentioned. In recent years, since melamine sponge resistance is required, a pencil hardness of 4 to 5H is required as the surface hardness, and the resin composition for gel coat of the present invention can be preferably applied.

[0070] The method for forming the gel coat layer using the resin composition for gel coat of the present invention is not particularly limited, and a conventionally known method can be used. Generally, a method of applying the resin composition for gel coat of the present invention to the surface of the object to be coated by a spray gun, brush, roller, etc. can be mentioned, but various methods are selected depending on the material, shape, surface state, etc. of the object to be coated. Among them, a spray gun is preferred from the viewpoints of productivity and versatility. As the gel coat supply method of the spray gun, a pressure feeding type, gravity type, or suction type can be preferably used.

[0071] The properties (viscosity, thixotropy, curability) of the resin composition for gel coat of the present invention are set (adjusted) according to the shape of the object to which the gel coat is applied, particularly the height, area, and shape of the vertical surface, the coating thickness of the gel coat to be applied, the ambient temperature, and the like. By adjusting the composition, excellent sprayability and moldability can be exhibited even under various conditions.

[0072] Furthermore, the fiber-reinforced plastic molded article of the present invention is characterized by having a layer made of a cured product of the resin composition for gel coat.

[0073] Examples of the fiber-reinforced plastic include glass fiber-reinforced plastic, carbon fiber-reinforced plastic, aramid fiber-reinforced plastic, and the like. Examples of the plastic in these reinforced plastics include cured products of unsaturated polyester resins and vinyl ester resins.

[0074] By using the gel coat formed with the resin composition for gel coat according to the present invention, the following three characteristics are greatly improved. Scratch resistance (property that scratches are not easily formed on the surface) Durability (property of continuously maintaining the original state even when exposed to warm water immersion, outdoor exposure, chemicals, etc.) Forming property (property that a smooth surface is easily formed without curing defects, bubbles, cracks, or unevenness occurring in the gel coat during the forming process)

Examples

[0075] Next, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples. Also, in the following, "parts" and "%" are all based on mass unless otherwise specified.

[0076] <(A) Unsaturated polyester or vinyl ester> (A1) 6510 (manufactured by Nippon Yupica Co., Ltd.) (A2) N-325 (manufactured by Japan Composite Co., Ltd.) (A3) FG-283 (manufactured by DIC MATERIALS CO., LTD.) (A4) 6650 (manufactured by JAPAN COMPOSITE CO., LTD.) The details of each product are shown in the table below. These contain styrene monomer (SM), which is an unsaturated monomer having one polymerizable unsaturated group (D).

[0077] [Table 1]

[0078] <(B) (Meth)acrylic monomer having three or more polymerizable unsaturated groups> (B1) Light Ester TMPA (trimethylolpropane trimethacrylate) (3-functional monomer), manufactured by Kyoeisha Chemical Co., Ltd. (B2) 1:1 mixture of Light Acrylate TMP-A (trimethylolpropane triacrylate) (3-functional monomer) and Light Acrylate PE-4A (4-functional monomer), manufactured by Kyoeisha Chemical Co., Ltd. (B3) PETA (pentaerythritol (tri / tetra) acrylate) (mixture of 3-functional monomer and 4-functional monomer), manufactured by Daicel Ornex Co., Ltd. (B4) AD-TMP (ditrimethylolpropane tetraacrylate) (4-functional monomer), manufactured by Shin-Nakamura Chemical Co., Ltd. (B5) DPHA (pentaerythritol (penta / hex) acrylate) (mixture of 5-functional monomer and 6-functional monomer), manufactured by Daicel Ornex Co., Ltd. (B6) Kayarad DPEA-12 (EO-modified dipentaerythritol hexaacrylate) (6-functional monomer), manufactured by Nippon Kayaku Co., Ltd.

[0079] <(C) Polyrotaxane having a polymerizable unsaturated group> (C1) Selm Super Polymer SA1303P (manufactured by Advance Soft Materials) (C2) Selm Super Polymer SM2403P (manufactured by Advance Soft Materials) (C3) Cellmus Super Polymer SA3403P (manufactured by Advanced Soft Materials Co., Ltd.)

[0080]

Table 2

[0081] The molecular structure of the polyrotaxane used is shown in Figure 1. The cyclic molecule is cyclodextrin, and the linear molecule is polyethylene glycol. In Figure 1, the polyethylene glycol chain is represented by a dotted line, and the cyclodextrin ring is represented by a four-membered ring surrounding the polyethylene glycol chain.

Chemical formula

[0082] <(D) Unsaturated monomer having one or two polymerizable unsaturated groups> (D1) Styrene (D2) Methyl methacrylate (D3) Ethylene glycol dimethacrylate

[0083] Examples 1 to 14 and Comparative Examples 1 to 6 Component (D) was added to components (A) to (C) shown in Table 3 and mixed, and the viscosity was adjusted so that the viscosity of a B-type viscometer was 130 ± 10 mPas (25°C) to prepare a resin composition for gel coat. Comparative Examples 3 to 6 correspond to conventional examples.

[0084]

Table 3

[0085] To 100 parts of the gel coat resin composition prepared in each example, 3 parts of silica powder (manufactured by Nippon Aerosil Co., Ltd., trade name: Aerosil #200) as a thixotropic agent were dispersed and mixed by high-speed stirring. Then, 10 parts of iron oxide black (manufactured by Daitai Chemical Co., Ltd., trade name: Toner Black) as a pigment, 0.3 part of cobalt octylate as a curing accelerator, 0.05 part of dimethylaniline (manufactured by Samsung Chemical Research Institute Co., Ltd.), 0.2 part of BYK A-501 (manufactured by BYK Chemie Japan Co., Ltd.) as a non-silicone defoaming agent, and 0.005 to 0.020 part of monoteritary butyl hydroquinone as a curing time adjuster were added, and the curing time at 25°C was adjusted to be 20 to 30 minutes.

[0086] Furthermore, immediately before painting, 1 part of an organic peroxide curing agent (methyl ethyl ketone peroxide, manufactured by Kayaku Nurion Co., Ltd., trade name: Kayamec M) was added and stirred to prepare a gel coat paint for various evaluations.

[0087] Using the obtained gel coat paint, the following evaluations were carried out. The evaluation results are shown in Table 4.

[0088] <Defoaming property> The gel coat paint was applied on a 30 cm × 30 cm glass plate, and after standing at 25°C for 2 hours, the molded surface peeled off from the glass plate was visually confirmed. Evaluation was carried out according to the following criteria. 〇: When no bubbles can be visually confirmed and there is substantially no problem △: When several bubbles can be visually confirmed ×: When innumerable bubbles can be visually confirmed

[0089] <Film-forming property> The gel coat paint was applied on a 30 cm × 30 cm glass plate, and after standing at room temperature for 15 minutes, it was heated and cured at 60°C for 30 minutes. When standing at room temperature, the surface state was visually confirmed. Evaluation was carried out according to the following criteria. 〇: When the surface is smooth and there is no problem ×: When cracks occur and it does not reach the practical level

[0090] On the paint for gel coat on the surface of the glass plate, a mixture of 100 parts by weight of unsaturated polyester resin (manufactured by Japan Composite Co., Ltd., Polyhope N-33PT) and 1 part of curing agent (ketone peroxide type, manufactured by Kayaku Akzo, Kayamec M) was impregnated and degassed with chopped strand mat (manufactured by Nitto Boseki) MC450A in three plies at a ratio of 70:30 of unsaturated polyester resin to glass mat, and then demolded after heating at 60°C for 2 hours to produce an FRP plate with gel coat. The following evaluations were performed using the obtained FRP plate. The evaluation results are shown in Table 4.

[0091] <Hot water resistance> After the FRP plate was brought into contact with hot water at 90°C for 300 hours, the appearance of the gel coat was visually confirmed. Evaluation was carried out according to the following criteria. 〇: When there is no significant change compared to before the test △: When discoloration and change in gloss are confirmed, but it reaches a certain practical level ×: When significant discoloration, change in gloss, swelling, etc. are confirmed and it does not reach a practical level

[0092] <Weather resistance> Using the FRP plate, a weather resistance test based on JIS A1415 was carried out for 200 hours using a sunshine weather meter. The appearance of the gel coat was visually confirmed. Evaluation was carried out according to the following criteria. 〇: When there is not much change compared to before the test △: When at least one of discoloration and change in gloss is confirmed, but it reaches a certain practical level ×: When significant discoloration, significant change in gloss, cracks, etc. are confirmed and it does not reach a practical level

[0093] <Chemical resistance> After the FRP plate was immersed in 1% caustic soda, 1% sulfuric acid, and saturated calcium hydroxide for 24 hours, the appearance of the gel coat was visually confirmed. Evaluation was carried out according to the following criteria. 〇: When there is no change compared to before the test △: When slight discoloration and change in gloss are confirmed, but it reaches a certain practical level ×: Significant discoloration or gloss change is observed, and the level is not yet practical.

[0094] <Surface hardness> Using the FRP boards, a hardness test was carried out based on JIS K5600 to measure the pencil hardness.

[0095] <Scratch resistance> The FRP board was rubbed with a melamine sponge (Gekiochikun, manufactured by LEC Co., Ltd.) 100 times with a constant force, and the appearance was visually inspected. Evaluation was made according to the following criteria. ○: No change compared to before the test △: Changes in gloss and scratches were observed, but the product was usable to a certain extent without any problems up to 50 times. ×: Even after 50 times, significant changes in gloss and noticeable scratches have been confirmed, and the level is not yet practical.

[0096] <Barcol hardness> The gel coat paint was poured between two glass plates with a 3mm thick silicon spacer in between, and a gel coat casting plate was produced by curing for 1 hour at room temperature and 2 hours at 60℃. The hardness was measured using a Barcol hardness tester GYZJ 934-1. The average was calculated after 10 repetitions.

[0097] [Table 4]

[0098] <Crack resistance, mold release> Using an actual mini bathtub mold, the appearance after molding and after lamination was visually observed, and the appearance was confirmed visually according to the scratch resistance method described above. Items that had cracks during appearance observation were marked with an X. The evaluation results are shown in Table 4.

[0099] [Table 5]

[0100] In the case of a resin composition of Comparative Example 5 in a minibus tub having a complicated shape, the shape followability was poor, and defects such as cracks and mold release occurred during gel coat curing, and a beautiful molded product could not be obtained. Further, in the resin composition of Comparative Example 6, although a molded product was obtained, the scratch resistance by a melamine sponge could not be exhibited. On the other hand, in the resin composition of the Example, it had shape followability, had no defects such as cracks and mold release, and a beautiful molded product could be obtained, and the target scratch resistance could be obtained.

Claims

1. (A) 20 to 45% by weight of an unsaturated polyester or vinyl ester, (B) 20 to 45% by weight of a (meth)acrylic monomer, (C) 0.8 to 5% by weight of a polyrotaxane, and (D) 20 to 50% by weight of an unsaturated monomer A resin composition for gel coat containing the same.

2. The resin composition for gel coat according to Claim 1, wherein (B) the (meth)acrylic monomer is at least one selected from trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and alkoxy-modified products thereof.

3. The resin composition for gel coat according to Claim 1 or 2, wherein (C) the polyrotaxane has a (meth)acryloyl group.

4. A paint containing the resin composition for gel coat according to any one of Claims 1 to 3.

5. A fiber-reinforced plastic molded article having a layer made of a cured product of the resin composition for gel coat according to any one of Claims 1 to 3.

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