Coating composition and article coated with said coating composition

Abstract

To provide a coating composition from which a coating film that is excellent in adhesion to a plastic base material, resistance to water adhesion and resistance to an aromatizing agent, and is also excellent in soft property can be obtained.SOLUTION: A coating composition contains a modified acrylic resin (X) and polyester polyol (Y), wherein a mass ratio (X / Y) of the modified acrylic resin (X) to the polyester polyol (Y) is 10 / 90 to 90 / 10, and the modified acrylic resin (X) is a modified acrylic resin obtained by reaction of an unsaturated monomer mixture (B) containing an unsaturated monomer (b1) having methyl methacrylate and a hydroxyl group, an unsaturated monomer (b2) having a carboxyl group and an unsaturated monomer (b3) having an alkyl group having 2 to 8 carbon atoms as essential components, in the presence of polycarbonate diol (A) containing 1,5-pentane diol and 1,6-hexane diol as raw materials.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a coating composition and an article coated with the coating composition. [Background technology]

[0002] In recent years, plastic molded products have been widely used in the bodies and remote controls of home appliances such as refrigerators, televisions, and air conditioners, the housings of information terminals such as mobile phones, smartphones, and personal computers, toys, and 3D molded products. While these plastic molded products are sometimes used as they are, they are often painted to impart design features. Traditionally, designs imparted have often been visually recognizable through color, gloss, etc., but recently, there has been an increase in the use of paint to impart tactile sensations such as a soft feel, which can be felt when touched with the fingers.

[0003] As a material for imparting the above-mentioned soft feel, an active energy ray-curable top coat composition has been proposed, which contains an active energy ray-curable urethane (meth)acrylate obtained by reacting an isocyanate compound obtained by reacting a polyester polyol having two or more hydroxyl groups per molecule with hexamethylene diisocyanate, and further reacting this with a (meth)acrylate having a hydroxyl group, and a photopolymerization initiator (see, for example, Patent Document 1). However, this active energy ray-curable top coat composition has the problem of insufficient tactile sensation, such as high elasticity and low grip, which are necessary for soft feel.

[0004] Therefore, there has been a demand for a coating composition that can provide a coating film that has excellent adhesion to plastic substrates, water resistance, etc., and also has an excellent soft feel. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6536925 Summary of the Invention [Problem to be solved by the invention]

[0006] The problem to be solved by the present invention is to provide a coating composition which is capable of producing a coating film which has excellent adhesion to plastic substrates, water-resistant adhesion, and fragrance resistance, as well as excellent soft feel, and an article coated with said coating composition. [Means for solving the problem]

[0007] As a result of intensive research into solving the above problems, the present inventors discovered that the above problems can be solved by using a coating composition containing a specific modified acrylic resin and a polyester polyol in a specific ratio, and thus completed the invention.

[0008] That is, the present invention relates to a coating composition containing a modified acrylic resin (X) and a polyester polyol (Y), wherein the mass ratio (X / Y) of the modified acrylic resin (X) to the polyester polyol (Y) is 10 / 90 to 90 / 10, and the modified acrylic resin (X) is a modified acrylic resin obtained by reacting an unsaturated monomer mixture (B) containing, as essential components, methyl methacrylate, an unsaturated monomer having a hydroxyl group (b1), an unsaturated monomer having a carboxyl group (b2), and an unsaturated monomer having an alkyl group of 2 to 8 carbon atoms (b3), in the presence of a polycarbonate diol (A) made from 1,5-pentanediol and 1,6-hexanediol; and to an article coated with the coating composition. [Effects of the Invention]

[0009] The coating composition of the present invention has excellent adhesion to plastic substrates, water-resistant adhesion, and fragrance resistance, and can produce a coating film that has a soft feel when touched with the fingers. Therefore, the coating composition can be suitably used as a coating material for coating various articles such as the interior and exterior of various vehicles such as automobiles and railway cars, the housings of electronic devices such as mobile phones, smartphones, tablet devices, personal computers, digital cameras, and game consoles, the housings of home appliances such as televisions, refrigerators, washing machines, and air conditioners, furniture, toys, interior decoration, and 3D molded products. DETAILED DESCRIPTION OF THE INVENTION

[0010] The coating composition of the present invention is a coating composition containing a modified acrylic resin (X) and a polyester polyol (Y), wherein the mass ratio (X / Y) of the modified acrylic resin (X) to the polyester polyol (Y) is 10 / 90 to 90 / 10, and the modified acrylic resin (X) is a modified acrylic resin obtained by reacting an unsaturated monomer mixture (B) containing, as essential components, methyl methacrylate, an unsaturated monomer having a hydroxyl group (b1), an unsaturated monomer having a carboxyl group (b2), and an unsaturated monomer having an alkyl group of 2 to 8 carbon atoms (b3), in the presence of a polycarbonate diol (A) made from 1,5-pentanediol and 1,6-hexanediol.

[0011] The modified acrylic resin (X) is a modified acrylic resin obtained by reacting an unsaturated monomer mixture (B) in the presence of a polycarbonate diol (A).

[0012] The polycarbonate diol (A) is a polycarbonate diol made from 1,5-pentanediol and 1,6-hexanediol as raw materials, and is obtained, for example, by reacting 1,5-pentanediol and 1,6-hexanediol with a carbonate ester or phosgene.

[0013] The unsaturated monomer mixture (B) contains, as essential components, methyl methacrylate, an unsaturated monomer (b1) having a hydroxyl group, an unsaturated monomer (b2) having a carboxyl group, and an unsaturated monomer (b3) having an alkyl group having 2 to 8 carbon atoms, and the mass ratio of the unsaturated monomer (b2) is 2 to 10 mass %.

[0014] Examples of the unsaturated monomer (b1) having a hydroxyl group include 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxy-n-butyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxy-n-butyl (meth)acrylate, 3-hydroxy-n-butyl (meth)acrylate, 1,4-cyclohexanedimethanol mono(meth)acrylate, glycerin mono(meth)acrylate, polyoxyethylene mono(meth)acrylate, polyoxypropylene mono(meth)acrylate, polyoxybutylene mono(meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 2-(meth)acryloyloxyethyl-2-hydroxyethyl phthalate, polycaprolactone-modified hydroxyethyl mono(meth)acrylate, etc. Among these, 2-hydroxyethyl (meth)acrylate is preferred because it provides excellent appearance, water-resistant adhesion, and fragrance resistance of the resulting coating film. These unsaturated monomers (b1) can be used alone or in combination of two or more.

[0015] In the present invention, "(meth)acrylic acid" refers to either or both of methacrylic acid and acrylic acid, "(meth)acrylate" refers to either or both of methacrylate and acrylate, and "(meth)acryloyl group" refers to either or both of methacryloyl group and acryloyl group.

[0016] Examples of the unsaturated monomer (b2) having a carboxyl group include unsaturated monocarboxylic acids such as (meth)acrylic acid, crotonic acid, β-carboxyethyl (meth)acrylate, ω-carboxy-polycaprolactone mono(meth)acrylate, 2-(meth)acryloyloxyethyl succinate, and 2-(meth)acryloyloxyethyl hexahydrophthalic acid; unsaturated dicarboxylic acids such as maleic acid, fumaric acid, and itaconic acid, and half esters of these unsaturated dicarboxylic acids. Among these, (meth)acrylic acid is preferred because it provides excellent resistance to fragrances in the resulting coating film. These unsaturated monomers (b2) can be used alone or in combination of two or more.

[0017] Examples of the unsaturated monomer (b3) having an alkyl group having 2 to 8 carbon atoms include ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, etc. These unsaturated monomers (b3) can be used alone or in combination of two or more.

[0018] Furthermore, as a component of the unsaturated monomer mixture (B), a monomer (b4) other than the above-mentioned essential raw materials, methyl methacrylate, unsaturated monomer (b1), unsaturated monomer (b2), and unsaturated monomer (b3), may be used. Examples of other monomers (b4) include methyl acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, behenyl (meth)acrylate, 4-tert-butylcyclohexyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, benzyl (meth)acrylate; acrylamide, N,N-dimethyl (meth)acrylamide, (meth)acrylonitrile, 3-(meth)acryloyloxypropyltrimethoxysilane, N,N-dimethylaminoethyl (meth)acrylate, 2-(meth)acryloyloxyethyl acid phosphate, glycidyl (meth)acrylate, vinyl acetate, styrene, α-methylstyrene, p-methylstyrene, p-methoxystyrene, and diacrylate compounds such as ethylene glycol diacrylate. These unsaturated monomers can be used alone or in combination of two or more.

[0019] The unsaturated monomer mixture (B) contains methyl (meth)acrylate, the unsaturated monomer (b1), the unsaturated monomer (b2), and the unsaturated monomer (b3) as essential components. In order to provide a coating film with excellent water resistance and fragrance resistance, the mass ratio of methyl (meth)acrylate in the unsaturated monomer mixture (B) is preferably 30 to 95 mass%, more preferably 55 to 90 mass%.

[0020] The mass ratio of the unsaturated monomer (b1) in the unsaturated monomer mixture (B) is preferably 1 to 40 mass %, more preferably 3 to 30 mass %, in order to provide a coating film with excellent water resistance and fragrance resistance.

[0021] The mass ratio of the unsaturated monomer (b2) in the unsaturated monomer mixture (B) is preferably 2 to 10 mass %, more preferably 3 to 8 mass %, in order to provide a coating film with excellent water resistance and fragrance resistance.

[0022] The mass ratio of the unsaturated monomer (b3) in the unsaturated monomer mixture (B) is preferably 1 to 30 mass %, more preferably 3 to 15 mass %, in order to provide a coating film with excellent water resistance and fragrance resistance.

[0023] The glass transition temperature of the unsaturated monomer mixture (B) calculated by the FOX formula (hereinafter abbreviated as "design Tg") is preferably 60 to 110°C, since this improves the chemical resistance of the resulting coating film.

[0024] In the present invention, the glass transition temperature calculated by the FOX formula is FOX formula: 1 / Tg = W1 / Tg1 + W2 / Tg2 + ... (Tg: glass transition temperature to be determined, W1: weight fraction of component 1, Tg1: glass transition temperature of homopolymer of component 1) The glass transition temperature of the homopolymer of each component is calculated as follows: The values ​​used were those described in Polymer Handbook (4th Edition) by J. Brandrup, EH Immergut, and EA Grulke (Wiley Interscience).

[0025] The modified acrylic resin (X) is preferably obtained by radically polymerizing the unsaturated monomer mixture (B) in the presence of the polycarbonate diol (A) and a solvent, because this method is simple.

[0026] The radical polymerization method is a method in which each monomer as a raw material is dissolved in a solvent and a polymerization reaction is carried out in the presence of a polymerization initiator.The solvent that can be used in this case includes, for example, aromatic hydrocarbon compounds such as toluene and xylene; alicyclic hydrocarbon compounds such as cyclohexane, methylcyclohexane and ethylcyclohexane; ketone compounds such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; ester compounds such as ethyl acetate, n-butyl acetate, isobutyl acetate and propylene glycol monomethyl ether acetate; alcohol compounds such as n-butanol, isopropyl alcohol and cyclohexanol; glycol compounds such as ethylene glycol monobutyl ether and propylene glycol monomethyl ether; aliphatic hydrocarbon compounds such as heptane, hexane, octane and mineral turpentine.

[0027] Examples of the polymerization initiator include ketone peroxide compounds such as cyclohexanone peroxide, 3,3,5-trimethylcyclohexanone peroxide, and methylcyclohexanone peroxide; 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(tert-butylperoxy)cyclohexane, n-butyl-4,4-bis(tert-butylperoxy)valerate, and 2,2-bis(4,4-ditert-butylperoxycyclohexyl). peroxyketal compounds such as 2,2-bis(4,4-ditert-amylperoxycyclohexyl)propane, 2,2-bis(4,4-ditert-hexylperoxycyclohexyl)propane, 2,2-bis(4,4-ditert-octylperoxycyclohexyl)propane, and 2,2-bis(4,4-dicumylperoxycyclohexyl)propane; hydroperoxides such as cumene hydroperoxide and 2,5-dimethylhexane-2,5-dihydroperoxide dialkyl peroxide compounds such as 1,3-bis(tert-butylperoxy-m-isopropyl)benzene, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, diisopropylbenzene peroxide, tert-butylcumyl peroxide, and di-tert-butyl peroxide; diacyl peroxide compounds such as decanoyl peroxide, lauroyl peroxide, benzoyl peroxide, and 2,4-dichlorobenzoyl peroxide; bis(tert- peroxycarbonate compounds such as tert-butylperoxy-2-ethylhexanoate, tert-butylperoxybenzoate, and 2,5-dimethyl-2,5-di(benzoylperoxy)hexane; and organic peroxides such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methyl)butyronitrile, and 1,1'-azobis(cyclohexane-1-carbonitrile).

[0028] Furthermore, the mass ratio (A / B) of the polycarbonate diol (A) to the unsaturated monomer mixture (B) is preferably in the range of 2 / 98 to 80 / 20, more preferably in the range of 3 / 97 to 70 / 30, and even more preferably in the range of 4 / 96 to 60 / 40, since this further improves the water-resistant adhesion and fragrance resistance of the resulting coating film.

[0029] The hydroxyl value of the modified acrylic resin (X) is preferably from 20 to 150 mgKOH / g, more preferably from 60 to 130, since this further improves the resistance of the resulting coating film to fragrances.

[0030] The weight-average molecular weight (Mw) of the modified acrylic resin (X) is preferably 2,000 to 50,000, more preferably 4,000 to 30,000, since this further improves the water-resistant adhesion and fragrance-resistant properties of the resulting coating film. Here, the weight-average molecular weight (Mw) is a value measured by gel permeation chromatography (hereinafter abbreviated as "GPC") and converted into polystyrene.

[0031] The polyester polyol (Y) is a polyol having a plurality of ester bonds, and is obtained, for example, by reacting a polycarboxylic acid with a polyol.

[0032] The hydroxyl value of the polyester polyol (Y) is preferably from 20 to 200 mgKOH / g, more preferably from 40 to 180 mgKOH / g, because this further improves the balance between the physical properties of the resulting coating film, such as adhesion to the substrate, water resistance, and resistance to fragrances, and the soft feel.

[0033] The number average molecular weight of the polyester polyol (Y) is preferably from 1,000 to 8,000, more preferably from 1,300 to 6,000, because this improves the balance between the physical properties of the resulting coating film, such as adhesion to the substrate, water resistance, and resistance to fragrances, and the soft feel.

[0034] In the coating composition of the present invention, the mass ratio (X / Y) of the modified acrylic resin (X) to the polyester polyol (Y) is 10 / 90 to 90 / 10, but a mass ratio of 20 / 80 to 80 / 20 is preferred, and a mass ratio of 25 / 75 to 75 / 25 is more preferred, as this improves the balance between the physical properties of the resulting coating film, such as adhesion to the substrate, water resistance, and fragrance resistance, and the soft feel.

[0035] The molar ratio (OHX / OHY) of the hydroxyl groups (OHX) of the modified acrylic resin (X) to the hydroxyl groups (OHY) of the polyester polyol (Y) is preferably 90 / 10 to 15 / 85, more preferably 80 / 20 to 25 / 75, because this further improves the balance between the physical properties of the resulting coating film, such as adhesion to the substrate, water resistance, and resistance to fragrances, and the soft feel.

[0036] The coating composition of the present invention contains the modified acrylic resin (X) and the polyester polyol (Y), and preferably contains a curing agent, as this further improves the physical properties of the resulting coating film.

[0037] Examples of the curing agent include polyisocyanate compounds and amino resins, with polyisocyanate compounds being preferred because the resulting coating film has excellent water-resistant adhesion and fragrance-resistant properties. These curing agents can be used alone or in combination of two or more.

[0038] Examples of the polyisocyanate compound include aromatic diisocyanate compounds such as tolylene diisocyanate, diphenylmethane diisocyanate, m-xylylene diisocyanate, and m-phenylenebis(dimethylmethylene)diisocyanate; and aliphatic or alicyclic diisocyanate compounds such as hexamethylene diisocyanate, lysine diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, 2-methyl-1,3-diisocyanatocyclohexane, 2-methyl-1,5-diisocyanatocyclohexane, 4,4'-dicyclohexylmethane diisocyanate, and isophorone diisocyanate.

[0039] Examples of the polyisocyanate compound that can be used include prepolymers having an isocyanate group obtained by subjecting the above diisocyanate compounds to an addition reaction with a polyhydric alcohol; compounds having an isocyanurate ring obtained by cyclotrimerizing the above diisocyanate compounds; polyisocyanate compounds having a urea bond or a biuret bond obtained by reacting the above diisocyanate compounds with water; homopolymers of acrylic monomers having an isocyanate group, such as 2-isocyanatoethyl (meth)acrylate, 3-isopropenyl-α,α-dimethylbenzyl isocyanate, and (meth)acryloyl isocyanate; and copolymers having an isocyanate group obtained by copolymerizing the above acrylic monomers having an isocyanate group with monomers such as other acrylic monomers, vinyl ester compounds, vinyl ether compounds, aromatic vinyl monomers, and fluoroolefins.

[0040] The above polyisocyanate compounds can be used alone or in combination of two or more kinds.

[0041] When the curing agent is a polyisocyanate compound, the amount of the compound is preferably an equivalent ratio (isocyanate group / hydroxyl group) of the isocyanate group in the polyisocyanate compound to the hydroxyl group in the modified acrylic resin of the present invention of 0.5 to 2.0, more preferably 0.7 to 1.3, in order to obtain a coating film with high strength.

[0042] The urethanization reaction can be carried out in the presence of a urethanization catalyst to promote the reaction. Examples of the urethanization catalyst include amine compounds such as triethylamine, organotin compounds such as dibutyltin dioctate, dibutyltin dilaurate, dioctyltin dilaurate, octyltin trilaurate, dioctyltin dineodecanoate, dibutyltin diacetate, dioctyltin diacetate, and tin dioctylate, and organometallic compounds such as zinc octylate (zinc 2-ethylhexanoate).

[0043] The coating composition of the present invention preferably contains a matting agent to impart a stronger soft feel to the coating film. Examples of the matting agent include inorganic particles such as talc, calcium carbonate, clay, kaolin, and silica, and organic particles such as polyethylene, polypropylene, acrylic, urethane, polyester, polyamide, polystyrene, silicone, melamine, polybutadiene, polyethylene, and nylon. Among these, inorganic particles are preferred, and silica particles are more preferred, as they further improve the balance between physical properties such as resistance to fragrances and soft feel. The average particle diameter of the silica particles is preferably 1 to 20 μm, more preferably 5 to 15 μm. The average particle diameter is measured using a laser diffraction / scattering particle size analyzer. These matting agents can be used alone or in combination of two or more.

[0044] The content of the matting agent in the coating composition of the present invention is preferably 5 to 100 parts by mass, more preferably 8 to 80 parts by mass, and even more preferably 8 to 30 parts by mass, per 100 parts by mass of the total of the modified acrylic resin (X) and the polyester polyol (Y), because this further improves the balance between the soft feel and the coating film smoothness.

[0045] The coating composition of the present invention may contain additives other than those mentioned above, such as solvents, antifoaming agents, viscosity modifiers, light stabilizers, weather stabilizers, heat stabilizers, ultraviolet absorbers, antioxidants, matting agents, leveling agents, pigment dispersants, etc. Pigments such as titanium oxide, calcium carbonate, aluminum powder, copper powder, mica powder, iron oxide, carbon black, phthalocyanine blue, toluidine red, perylene, quinacridone, and benzidine yellow may also be used.

[0046] Each of the above-mentioned raw materials used in the coating composition of the present invention can also be a biomass raw material.

[0047] The coating composition of the present invention has excellent adhesion to plastic substrates, water-resistant adhesion, and fragrance resistance, and can produce a coating film with a strong soft feel, making it suitable for use as a coating for painting articles such as plastic molded articles. Examples of articles that can be coated with the coating of the present invention include the interior and exterior of various vehicles such as automobiles and railway cars, housings for electronic devices such as mobile phones, smartphones, tablet devices, personal computers, digital cameras, and game consoles, housings for home appliances such as televisions, refrigerators, washing machines, and air conditioners, furniture, interior decor, and 3D molded articles.

[0048] Examples of methods for applying the coating composition of the present invention include spraying, applicators, bar coaters, gravure coaters, roll coaters, comma coaters, knife coaters, air knife coaters, curtain coaters, kiss coaters, shower coaters, wheeler coaters, spin coaters, dipping, screen printing, etc. After application, a coating film can be formed by drying at room temperature to 120°C. [Example]

[0049] The present invention will be described in more detail below with reference to specific examples. In the present invention, the hydroxyl value is measured in accordance with JIS test method K 0070-1992. The weight average molecular weight (Mw) is measured under the following GPC measurement conditions.

[0050] [GPC measurement conditions] Measurement equipment: High-speed GPC equipment (Tosoh Corporation "HLC-8220GPC") Column: The following columns manufactured by Tosoh Corporation were connected in series and used. "TSKgel G5000" (7.8mm I.D. x 30cm) x 1 "TSKgel G4000" (7.8mm I.D. x 30cm) x 1 "TSKgel G3000" (7.8mm I.D. x 30cm) x 1 "TSKgel G2000" (7.8mmI.D. x 30cm) x 1 Detector: RI (differential refractometer) Column temperature: 40℃ Eluent: tetrahydrofuran (THF) Flow rate: 1.0mL / min Injection volume: 100 μL (sample concentration 4 mg / mL in tetrahydrofuran solution) Standard sample: A calibration curve was prepared using the following monodisperse polystyrene.

[0051] (monodisperse polystyrene) Tosoh Corporation's "TSKgel Standard Polystyrene A-500" Tosoh Corporation's "TSKgel Standard Polystyrene A-1000" Tosoh Corporation's "TSKgel Standard Polystyrene A-2500" Tosoh Corporation's "TSKgel Standard Polystyrene A-5000" "TSKgel Standard Polystyrene F-1" manufactured by Tosoh Corporation Tosoh Corporation's "TSKgel Standard Polystyrene F-2" Tosoh Corporation's "TSKgel Standard Polystyrene F-4" Tosoh Corporation's "TSKgel Standard Polystyrene F-10" Tosoh Corporation's "TSKgel Standard Polystyrene F-20" Tosoh Corporation's "TSKgel Standard Polystyrene F-40" Tosoh Corporation's "TSKgel Standard Polystyrene F-80" Tosoh Corporation's "TSKgel Standard Polystyrene F-128" Tosoh Corporation's "TSKgel Standard Polystyrene F-288" Tosoh Corporation's "TSKgel Standard Polystyrene F-550"

[0052] (Synthesis Example 1: Synthesis of modified acrylic resin (X-1)) A flask equipped with a cooling tube, thermometer, dropping funnel, and stirrer was charged with 400 parts by mass of polycarbonate diol (Asahi Kasei Chemicals Corporation's "Duranol T5650J," hydroxyl value 140, number average molecular weight 800) and 500 parts by mass of propylene glycol monomethyl ether acetate, and the internal temperature was raised to 120°C. Next, a mixture (designed Tg 79°C) of 450 parts by mass of methyl methacrylate, 30 parts by mass of ethyl acrylate, 70 parts by mass of 2-hydroxyethyl acrylate, 50 parts by mass of methacrylic acid, 100 parts by mass of propylene glycol monomethyl ether acetate, and 40 parts by mass of tert-butylperoxy 2-ethylhexanoate was added dropwise over 5 hours. After the dropwise addition was completed, the reaction was continued at the same temperature for 17 hours, and then the mixture was diluted with propylene glycol monomethyl ether acetate to a nonvolatile content of 60% by mass, yielding a solution of modified acrylic resin (X-1) with a mass ratio (A / B) of 40 / 60, a solids hydroxyl value of 100, and a weight-average molecular weight of 12,600.

[0053] (Synthesis Example 2: Synthesis of modified acrylic resin (X-2)) A flask equipped with a cooling tube, thermometer, dropping funnel, and stirrer was charged with 80 parts by weight of the polycarbonate diol and 350 parts by weight of propylene glycol monomethyl ether acetate, and the internal temperature was raised to 135°C. Next, a mixture consisting of 325 parts by weight of methyl methacrylate, 313 parts by weight of 2-hydroxyethyl acrylate, 6 parts by weight of methacrylic acid, 276 parts by weight of cyclohexyl methacrylate, 300 parts by weight of propylene glycol monomethyl ether acetate, and 10 parts by weight of tert-butyl peroxybenzoate (design Tg 44°C) was added dropwise over 5 hours. After the dropwise addition was completed, the reaction was continued at the same temperature for 17 hours, and then diluted with propylene glycol monomethyl ether acetate to a nonvolatile content of 60% by weight. This gave a solution of modified acrylic resin (X-2) with a mass ratio (A / B) of 8 / 92, a solids hydroxyl value of 163, and a weight-average molecular weight of 8,900.

[0054] (Synthesis Example 2: Synthesis of Unmodified Acrylic Resin (1)) A flask equipped with a cooling tube, thermometer, dropping funnel, and stirrer was charged with 500 parts by weight of propylene glycol monomethyl ether acetate, and the internal temperature was raised to 120 ° C. Next, a mixture of 770 parts by weight of methyl methacrylate, 50 parts by weight of ethyl acrylate, 150 parts by weight of 2-hydroxyethyl acrylate, 30 parts by weight of methacrylic acid, 100 parts by weight of propylene glycol monomethyl ether acetate, and 40 parts by weight of tert-butyl peroxy 2-ethylhexanoate (design Tg 73 ° C) was added dropwise over 5 hours. After the dropwise addition, the reaction was continued at the same temperature for 17 hours, and then diluted with propylene glycol monomethyl ether acetate to a nonvolatile content of 60% by weight. This gave a solution of unmodified acrylic resin (1) with a mass ratio (A / B) of 0 / 100, a solids hydroxyl value of 73, and a weight-average molecular weight of 12,600.

[0055] (Example 1: Preparation and evaluation of coating composition (1)) The solution of modified acrylic resin (X-1) obtained in Synthesis Example 1 and a solution of polyester polyol (Y-1) ("Burnoc D7-885-NT" manufactured by DIC Corporation, solid content hydroxyl value 102, nonvolatile content 80%) were mixed to a solid content mass ratio of 70 / 30 to obtain main component (1). The mass ratio (X / Y) of this main component (1) was 70 / 30, and the molar ratio (XOH / YOH) was 50 / 50. Next, 13% by mass of matting agent (1) (Evonik Industries AG "ACEMATT 3300", average particle size 9.5 μm), 0.5% by mass of leveling agent (BYK-331, BYK Japan Co., Ltd.), 0.1% by mass of curing catalyst (Nitto Kasei Co., Ltd. "Neostan U-100"), and 0.1% by mass of curing agent (Sumidur N-3300, Sumika Covestro Urethane Co., Ltd., non-volatile content 100%, NCO% 21.9%) were blended relative to the solid content of the base agent (1). The curing agent was blended in an amount such that the ratio of hydroxyl group equivalents in the base agent to isocyanate group equivalents in the curing agent was 1:1. Thereafter, the mixture was diluted with a mixed solvent (methyl isobutyl ketone / diacetone alcohol / ethyl acetate / isobutyl acetate = 30 / 30 / 30 / 10 (mass ratio)) so that the viscosity was 9 to 10 seconds (23°C) measured using an Anest Iwata Corporation "Viscosity Cup NK-2," to prepare a coating composition (1).

[0056] [Preparation of Cured Coating Film Y for Evaluation]

[0057] [Adhesion evaluation] The paint (1) obtained above was spray-coated onto a PC (polycarbonate) substrate (50 mm × 70 mm × 1 mm) so that the film thickness after drying would be 20 to 30 μm, and the coating was dried by heating in a dryer at 80°C for 30 minutes, and then dried at 25°C for 7 days to produce a cured coating film for evaluation. The cured coating film X for evaluation obtained above was cut with a cutter to make 1 mm wide squares, so that the number of squares was 100. Cellophane tape was then applied so as to cover all of the squares, and the tape was quickly peeled off four times. The adhesion was evaluated based on the number of squares remaining adhered, according to the following criteria. ○:100 pieces △:70~99 pieces ×: 69 or less

[0058] [Evaluation of water-resistant adhesion] The cured coating film for evaluation obtained in the same manner as in the above adhesion evaluation was immersed in water at 40°C for 240 hours, and then the same procedure as in the above adhesion evaluation was repeated to evaluate the water-resistant adhesion according to the following criteria. ○:100 pieces △:70~99 pieces ×: 69 or less

[0059] [Evaluation of resistance to fragrances] The paint (1) obtained above was spray-coated onto an ABS (acrylonitrile-butadiene-styrene copolymer) substrate (50 mm × 70 mm × 1 mm) so that the film thickness after drying would be 20 to 30 μm, and the coating was dried by heating in a dryer at 80°C for 30 minutes, and then dried at 25°C for 7 days to produce a cured coating film for evaluation. A piece of air freshener (Little Tree Air Freshener "Royal Pine") cut to a size of 15 mm x 15 mm was placed on the cured coating film for evaluation obtained above, and the film was dried at 74°C for 4 hours while a 500 g weight was applied. After that, the air freshener was removed and the appearance of the coating film was visually observed, and the air freshener resistance was evaluated according to the following criteria. ◎: No trace 〇: Slight traces △: Traces present ×: The base material of the substrate is exposed

[0060] [Evaluation of tactile sensation] The surface of the cured coating film for evaluation obtained in the same manner as in the above evaluation of adhesion was touched with a finger, and the feel was evaluated according to the following criteria. ◎: Very soft feel ○: Strong soft feel △: Weak soft feel ×: No soft feel

[0061] (Example 2: Preparation and evaluation of coating composition (2)) A coating composition (2) was prepared in the same manner as in Example 1, except that the mass ratio (X / Y) was changed to 50 / 50.

[0062] (Example 3: Preparation and evaluation of coating composition (3)) A coating composition (3) was prepared in the same manner as in Example 1, except that the solution of modified acrylic resin (X-1) was changed to a solution of modified acrylic resin (X-2) and the mass ratio (X / Y) was changed to 50 / 50.

[0063] (Example 4: Preparation and evaluation of coating composition (4)) A coating composition (4) was prepared in the same manner as in Example 1, except that the matting agent (1) was changed to a matting agent (2) ("ACEMATT OK520" manufactured by Evonik Industries AG, average particle size 6.5 μm).

[0064] (Example 5: Preparation and evaluation of coating composition (5)) A coating composition (5) was prepared in the same manner as in Example 1, except that the solution of polyester polyol (Y-1) was changed to polyester polyol (Y-2) ("Burnoc D-161" manufactured by DIC Corporation, non-volatile content 100%, solid content hydroxyl value 170) and the mass ratio (X / Y) was changed to 30 / 70.

[0065] (Example 6: Preparation and evaluation of coating composition (6)) A coating composition (6) was prepared in the same manner as in Example 1, except that the solution of modified acrylic resin (X-1) was changed to a solution of modified acrylic resin (X-2), the solution of polyester polyol (Y-1) was changed to polyester polyol (Y-2), and the mass ratio (X / Y) was changed to 30 / 70.

[0066] (Example 7: Preparation and evaluation of coating composition (7)) A coating composition (7) was prepared in the same manner as in Example 1, except that the solution of polyester polyol (Y-1) was changed to polyester polyol (Y-2), the mass ratio (X / Y) was changed to 30 / 70, and 13 mass% of matting agent (1) was changed to 16 mass% of matting agent (2).

[0067] (Comparative Example 1: Preparation of Coating Composition (R1)) A coating composition (R1) was prepared in the same manner as in Example 1, except that the solution of modified acrylic resin (X-1) was replaced with a solution of unmodified acrylic resin (1).

[0068] (Comparative Example 2: Preparation of Coating Composition (R2)) A coating composition (R2) was prepared in the same manner as in Example 1, except that the solution of polyester polyol (Y-1) was changed to a solution of unmodified acrylic resin (1).

[0069] (Comparative Example 3: Preparation of Coating Composition (R3)) A coating composition (R3) was prepared in the same manner as in Example 1, except that the solution of polyester polyol (Y-1) was not added.

[0070] Table 1 shows the resin compositions and evaluation results of the coating compositions (1) to (5) obtained above.

[0071] [Table 1]

[0072] Table 2 shows the resin compositions and evaluation results of the coating compositions (6) to (7) and (R1) to (R3) obtained above.

[0073] [Table 2]

[0074] It was confirmed that the cured coating films obtained from Examples 1 to 5, which are the coating resin compositions of the present invention, were excellent in adhesion, water-resistant adhesion, resistance to fragrances, and soft feel.

[0075] On the other hand, Comparative Example 1 is an example in which an unmodified acrylic resin was used instead of the modified acrylic resin (X), and it was confirmed that the water-resistant adhesion and soft feel were insufficient.

[0076] Comparative Example 2 is an example in which an unmodified acrylic resin was used instead of polyester polyol (Y), but it was confirmed that the soft feel was insufficient.

[0077] Comparative Example 3 is an example in which polyester polyol (Y) was not used, and it was confirmed that the soft feel was insufficient.

Claims

1. A coating composition containing a modified acrylic resin (X) and a polyester polyol (Y), wherein the mass ratio (X / Y) of the modified acrylic resin (X) to the polyester polyol (Y) is 10 / 90 to 90 / 10, and the modified acrylic resin (X) is a modified acrylic resin obtained by reacting an unsaturated monomer mixture (B) containing, as essential components, methyl methacrylate, an unsaturated monomer having a hydroxyl group (b1), an unsaturated monomer having a carboxyl group (b2), and an unsaturated monomer having an alkyl group with 2 to 8 carbon atoms (b3), in the presence of a polycarbonate diol (A) made from 1,5-pentanediol and 1,6-hexanediol.

2. 2. The coating composition according to claim 1, wherein the molar ratio (OHX / OHY) of the hydroxyl groups (OHX) of the modified acrylic resin (X) to the hydroxyl groups (OHY) of the polyester polyol (Y) is 90 / 10 to 15 / 85.

3. A coating composition comprising the coating composition according to claim 1 or 2 and a curing agent.

4. An article coated with the coating composition of claim 3.

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