Two-component coating composition, coated molded body, method for manufacturing a coated molded body, and method for manufacturing an in-mold coated molded body

Abstract

The present invention provides a two-component coating composition for thermoplastic resins that can form coated molded articles with excellent curability and adhesion. [Solution] A two-component coating composition for thermoplastic resins, comprising a main component and a curing agent, wherein the main component contains a polyamine and a polyol, has a solid content concentration of 95% by mass or more, does not contain a catalyst, or contains 0.25 parts by mass or less of a catalyst per 100 parts by mass of the total content of the polyamine and polyol, and the curing agent contains a polyisocyanate, has a solid content concentration of 95% by mass or more.

Description

Technical Field

[0001] The present disclosure relates to a two-component coating composition, a coated molded article, a method for producing a coated molded article, and a method for producing an in-mold coated molded article.

Background Art

[0002] Molded articles obtained from thermoplastic resins are widely used in fields such as electric devices, automobiles, and housing equipment parts. These molded articles are usually painted to form a protective film on the surface. In two-component coating compositions, generally, a catalyst is added to increase the reaction rate.

[0003] For example, Patent Document 1 describes a two-component coating composition comprising a main component containing a hydroxyl group-containing component and a curing catalyst (C), and a curing agent containing an isocyanate compound (B), wherein the hydroxyl group-containing component contains a polyol (A), the hydroxyl value of the polyol (A) is 200 mgKOH / g or more and 1900 mgKOH / g or less, the content of the curing catalyst (C) is within the range of 0.25 to 10 parts by mass with respect to 100 parts by mass of the hydroxyl group-containing component, and the amount of the organic solvent contained in the two-component coating composition is 5 parts by mass or less with respect to 100 parts by mass of the two-component coating composition. Patent Document 2 describes a coating composition containing an isocyanate-reactive group-containing resin (A), a polyisocyanate compound (B), and a hydroxyl group-containing aromatic compound (C) having a number-average molecular weight in the range of 100 to 1000, wherein the solid content of the coating composition is 95% by mass or more. Patent Document 3 describes a method for in-mold coating, comprising the steps of: (a) forming a plastic substrate in a first mold hole of a mold having at least two holes to form a molded plastic substrate; (b) introducing the molded plastic substrate into a second mold hole of the mold; (c) introducing a coating composition into the second mold hole containing the substrate in order to coat the molded plastic substrate, wherein the coating composition comprises (i) a polymer containing an isocyanate reactive group; (ii) a polyisocyanate; (d) curing the composition in the second mold hole under curing conditions of a mold temperature of 62 to 105°C and an external mold pressure of at least 100 kgf / mm2 for a period of at least 60 seconds; and (e) opening the mold hole so that the coated molded substrate is released from the second mold hole by gravity alone or by suction alone. Patent Document 4 describes a method for producing aliphatic and / or alicyclic polyurethane molded parts by casting or reaction injection molding, comprising: A) A1) i) polyol or combination of polyols, and ii) OH-terminated trifunctional prepolymer formed from a trimer based on hexamethylene diisocyanate (HDI) having a hexamethylene diisocyanate-based trimer and / or biuret structure; A2) polyol or combination of polyols; and A3) at least one hydroxyl group having an amine and / or hydroxyl group. The invention also describes a method for reacting an isocyanate composition comprising: A4) a catalytic system of at least one organometallic compound combined with at least one amine catalyst; and B) i) 10 to 90% by weight of isophorone diisocyanate and / or methylene-bis(4-isocyanatocyclohexane); and ii) 10 to 90% by weight of trimers based on hexamethylene diisocyanate having a biuret structure and / or trimers based on hexamethylene diisocyanate. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-183455 [Patent Document 2] Patent No. 6949291 [Patent Document 3] Patent No. 6871157 [Patent Document 4] Special Publication No. 2009-532538 [Overview of the project] [Problems that the invention aims to solve]

[0005] In two-component coating compositions for thermoplastic resins, there are cases where it is necessary to achieve both curability and adhesion.

[0006] One embodiment of this disclosure aims to solve the problem of providing a two-component coating composition for thermoplastic resins that can form a coated molded article with excellent curability and adhesion. The problems that other embodiments of this disclosure aim to solve are to provide a coated molded article with good curing properties and excellent adhesion, a method for manufacturing a coated molded article, and a method for manufacturing an in-mold coated molded article, using the above two-component coating composition. [Means for solving the problem]

[0007] This disclosure includes the following aspects: <1> It has a main component and a hardening agent, The main ingredient is It contains polyamines and polyols. The solid content concentration is 95% by mass or higher. Either it does not contain a catalyst, or the catalyst content is 0.25 parts by mass or less per 100 parts by mass of the total content of polyamines and polyols. The hardening agent is Contains polyisocyanate, The solid content concentration is 95% by mass or higher. A two-component coating composition for thermoplastic resins. <2> It is an in-mold coating composition, <1> The two-component coating composition described above. <3> On a resin molded body containing a thermoplastic resin, <1> A method for producing a coated molded article, comprising the step of applying the two-component coating composition described above to form a cured film. <4> A process of clamping a mold that has a fixed mold section and a movable mold section, The process involves molding thermoplastic resin in a mold cavity to produce a resin molded product, into the mold cavity, <2> A step of injecting the two-component coating composition described above to form a coating on a resin molded body, A process of curing the coating to form a cured film, The process of removing the resin molded body with a cured film formed from the mold, A method for manufacturing an in-mold coated molded article, including the method described above. <5> A resin molded body containing a thermoplastic resin and a cured film formed on the resin molded body are included. The cured film is the cured product of the main component and the curing agent in a two-component coating composition. The main component contains a polyamine and a polyol, has a solid content concentration of 95% by mass or more, and either does not contain a catalyst, or the catalyst content is 0.25 parts by mass or less per 100 parts by mass of the total content of polyamine and polyol. The curing agent is a coated molded article containing polyisocyanate and having a solid content concentration of 95% by mass or more. <6> The thickness of the cured film is 40 μm to 1000 μm. <5> The coated molded body described above. [Effects of the Invention]

[0008] According to one embodiment of the present disclosure, a two-component coating composition for thermoplastic resins is provided that can form a coated molded article with excellent curability and adhesion. According to other embodiments of the present disclosure, a coated molded article with good curing properties and excellent adhesion, a method for manufacturing a coated molded article, and a method for manufacturing an in-mold coated molded article are provided using the above two-component coating composition.

Brief Description of the Drawings

[0009] [Figure 1] FIG. 1 is a diagram for explaining a method of manufacturing an in-mold coating formed body using an injection molding method.

Modes for Carrying Out the Invention

[0010] Hereinafter, the content according to the present disclosure will be described in detail. The description of the constituent elements described below may be made based on typical embodiments according to the present disclosure, but the present disclosure is not limited to such embodiments. In the present disclosure, a numerical range indicated by using "~" means a range including the numerical values described before and after "~" as the minimum value and the maximum value, respectively. In the numerical ranges described stepwise in the present disclosure, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the upper limit value or the lower limit value of the numerical range described in other stepwise descriptions. Further, in the numerical ranges described in the present disclosure, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the value shown in the examples. In the present disclosure, a combination of two or more preferred embodiments is a more preferred embodiment.

[0011] In the present disclosure, the amount of each component in the composition means the total amount of the plurality of substances present in the composition when there are a plurality of substances corresponding to each component in the composition, unless otherwise specified. In the present disclosure, the term "step" includes not only an independent step but also a step included in this term if the intended purpose of the step is achieved even when it cannot be clearly distinguished from other steps. In the present disclosure, (meth)acrylate is a concept including both acrylate and methacrylate.

[0012] [Two-component coating composition] The two-component coating composition according to this disclosure comprises a main component and a curing agent, wherein the main component contains a polyamine and a polyol, has a solid content concentration of 95% by mass or more, does not contain a catalyst, or contains 0.25 parts by mass or less of a catalyst per 100 parts by mass of the total content of the polyamine and polyol, and the curing agent contains a polyisocyanate, has a solid content concentration of 95% by mass or more.

[0013] The two-component coating composition according to this disclosure makes it possible to form a coated molded article with excellent curability and adhesion. The reason for this effect is not clear, but it is presumed to be as follows.

[0014] Traditionally, large amounts of catalyst were used to increase the reaction rate between the components of the main agent and the components of the hardening agent. The two-component coating composition according to this disclosure exhibits excellent curability even if it does not contain a catalyst, or if the catalyst content is 0.25 parts by mass or less per 100 parts by mass of the total content of polyamine and polyol, because the reaction rate is improved by including a polyamine in addition to the polyol. Furthermore, the two-component coating composition according to this disclosure exhibits excellent adhesion to resin molded articles because it does not contain a catalyst, or if the catalyst content is 0.25 parts by mass or less per 100 parts by mass of the total content of polyamine and polyol.

[0015] Patent Document 1 does not contain any description of polyamines. Patent Document 2 does not contain any description of a two-component composition comprising a main component and a curing agent. Patent documents 3 and 4 do not suggest reducing the amount of catalyst.

[0016] The main component and curing agent in the two-component coating composition relating to this disclosure will be described below.

[0017] <Main ingredient> The main components include polyamines and polyols.

[0018] (Polyamines) The inclusion of polyamines in the main component improves the reaction rate, thereby accelerating the curing speed. Polyamines are not particularly limited as long as they are compounds having two or more amino groups. The number of amino groups in the polyamine is not particularly limited, but is 2 or more, and preferably 2 to 20.

[0019] The polyamine may be an aliphatic polyamine, an alicyclic polyamine, or an aromatic polyamine. Furthermore, the polyamine may be a polyamidoamine or a polyetheramine.

[0020] Examples of aliphatic polyamines include ethylenediamine, propylenediamine, butylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, and pentaethylenehexamine.

[0021] Examples of aromatic polyamines include diethyldiaminotoluene, 4,4'-diamino-3,3'-dichlorodiphenylmethane, 2,4-diaminotoluene, 2,6-diaminotoluene, diethylmethylbenzenediamine (1-methyl-3,5-diethyl-2,4-diaminobenzene, 1-methyl-3,5-diethyl-2,6-diaminobenzene, etc.), 1,3,5-triethyl-2,6-diaminobenzene, 4,4'-diaminodiphenylmethane, 3,5,3',5'-tetraethyl-4,4'-diaminodiphenylmethane, 3,5-dimethylthio-2,4-toluenediamine, and 3,5-dimethylthio-2,6-toluenediamine.

[0022] Examples of alicyclic polyamines include 1,4-cyclohexanediamine, 1,3-cyclohexanediamine, and 1,3-cyclopentanediamine.

[0023] The amine equivalent of the polyamine is not particularly limited, but is, for example, 50 to 250.

[0024] The amine equivalent of a polyamine is calculated using the following formula. Amine equivalent = (Molecular weight of polyamine) / (Number of active hydrogen atoms)

[0025] The main ingredient may contain only one type of polyamine, or it may contain two or more types. In the main component, the polyamine content is preferably 3% to 35% by mass, and more preferably 5% to 30% by mass, relative to the total content of polyamines and polyols. When the polyamine content is within the above range, the reaction rate is moderately accelerated, and curability and adhesion are improved.

[0026] (Polyol) The polyol is not particularly limited as long as it is a compound having two or more hydroxyl groups. The number of hydroxyl groups in the polyol is not particularly limited, but is 2 or more, and preferably 2 to 20.

[0027] Examples of polyols include acrylic polyols, polyester polyols, polyurethane polyols, and polyether polyols.

[0028] Acrylic polyols are obtained by copolymerizing a hydroxyl group-containing (meth)acrylic acid ester with a compound having a polymerizable unsaturated group. Examples of hydroxyl group-containing (meth)acrylic acid esters include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. Examples of compounds having polymerizable unsaturated groups include styrene, vinyltoluene, (meth)acrylic acid, fumaric acid, maleic acid, (meth)acrylic acid esters, (meth)acrylamide, and (meth)acrylonitrile.

[0029] Polyester polyols can be obtained by dehydration condensation reactions of polyhydric alcohols such as ethylene glycol, diethylene glycol, 1,4-butanediol, 1,6-hexanediol, propylene glycol, glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol with polybasic carboxylic acids such as phthalic acid, maleic acid, trimellitic acid, adipic acid, glutaric acid, succinic acid, sebacic acid, pimelic acid, and suberic acid.

[0030] Polyurethane polyols are obtained by reacting the above-mentioned polyhydric alcohol with a polyisocyanate. Polyether polyols can be obtained, for example, by adding an alkylene oxide such as ethylene oxide or propylene oxide to the above-mentioned polyhydric alcohol.

[0031] In particular, from the viewpoint of reducing viscosity and improving workability, it is preferable that the polyol includes a polyester polyol.

[0032] The main component may contain only one type of polyol, or it may contain two or more types. In the main component, the polyol content is preferably 65% ​​to 97% by mass, and more preferably 70% to 95% by mass, relative to the total content of polyamine and polyol.

[0033] The main component may contain other components besides polyamines and polyols.

[0034] Other components include, for example, catalysts, colorants, brightening agents, fillers, dispersants, defoamers, UV absorbers, light stabilizers, and mold release agents.

[0035] (catalyst) The main component either contains no catalyst or contains 0.25 parts by mass or less of catalyst per 100 parts by mass of the total content of polyamine and polyol. "Catalyst content of 0.25 parts by mass or less" means that the main component may contain a catalyst as long as it does not significantly impair the balance between curability and adhesion, and a low catalyst content is desirable. If the main component contains a catalyst, there may be only one type of catalyst, or there may be two or more types.

[0036] If the main component contains a catalyst, the catalyst is preferably a metal catalyst. Examples of metal catalysts include tin-containing compounds, zinc-containing compounds, and bismuth-containing compounds.

[0037] Examples of tin-containing compounds include dibutyltin dilaurate, dibutyltin dimaleate, dioctyltin dilaurate, dioctyltin dimaleate, dioctyltin maleate, and tin octolate.

[0038] Examples of zinc-containing compounds include zinc octanoate, zinc octoate, zinc naphthenate, zinc fatty acid, diethylzinc, zinc hexacyanocobaltate complex, zinc acetate, zinc acetylacetonate, zinc tol oilate, zinc hydroxide, zinc-2-ethylhexoate, zinc octoate, zinc hexanoate, zinc 2-ethylhexanoate, zinc acetylacetonate, bis(zinc monoacetoacetate) oxide, bis(zinc monoacetate) oxide, zinc dibenzoylmethane, zinc-2-ethyloctoate, zinc bis(2-ethylhexanoate), and zinc laurate.

[0039] Examples of bismuth-containing compounds include bismuth carboxylate, bismuth neodecanoate, bismuth octoate, dibismuth trioxide, bismastris (2-ethylhexanoate), bismuth nitrate, bismastris (neodecanoate), bismuth carboxylate, bismuth 2-ethylhexanoate, bismuth octoate, and bismuth neodecanoate.

[0040] The catalyst content is 0.25 parts by mass or less, and more preferably 0.20 parts by mass or less, per 100 parts by mass of the total content of polyamine and polyol. A catalyst content of 0.25 parts by mass or less can further improve adhesion to the resin molded article. Furthermore, from the viewpoint of balancing curability and adhesion, it is preferable for the main component to contain a catalyst. When the main component contains a catalyst, the catalyst content is preferably more than 0 parts by mass, more preferably 0.02 parts by mass or more, and even more preferably 0.05 parts by mass or more, based on 100 parts by mass of the total content of polyamine and polyol.

[0041] The solid content concentration of the main ingredient is 95% by mass or higher. Solid content refers to components other than volatile components (water, organic solvents, etc.) contained in the main ingredient. The solid content concentration of the main component is preferably 98% by mass or higher, and may be 100% by mass.

[0042] The main component has a solid content concentration of 95% by mass or higher, making it suitable for in-mold coating.

[0043] <Hardening agent> The hardening agent contains polyisocyanate. The curing agent may contain only one type of polyisocyanate, or two or more types.

[0044] Polyisocyanates are not particularly limited as long as they are compounds having two or more isocyanate groups. The number of isocyanate groups in the polyisocyanate is not particularly limited, but is 2 or more, and preferably 2 to 5.

[0045] The polyisocyanate may be an aliphatic polyisocyanate, an alicyclic polyisocyanate, or an aromatic polyisocyanate.

[0046] Examples of polyisocyanates include tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), methylcyclohexane diisocyanate, bis(isocyanate-methyl)cyclohexane, isophorone diisocyanate, dimer acid diisocyanate, and lysine diisocyanate. The polyisocyanate may be a modified form of the above compound. Examples of modified compounds include biuret modified compounds, isocyanurate modified compounds, adduct modified compounds (e.g., trimethylolpropane adducts), allophanate modified compounds, and uretdione modified compounds.

[0047] The solid content concentration of the hardening agent is 95% by mass or higher. The solid content concentration of the curing agent is preferably 98% by mass or higher, and may be 100% by mass.

[0048] The hardening agent has a solid content concentration of 95% by mass or higher, making it suitable for in-mold coating.

[0049] <Application> The two-component coating composition relating to this disclosure is for use with thermoplastic resins. In other words, the two-component coating composition according to this disclosure is used to coat a thermoplastic resin. Generally, increasing the reaction temperature can accelerate the reaction rate; however, when coating a thermoplastic resin, the reaction temperature cannot be increased in order to suppress the deformation of the thermoplastic resin itself. The two-component coating composition according to this disclosure has excellent curability, allowing the reaction temperature to be set relatively low, making it suitable for use with thermoplastic resins.

[0050] Examples of thermoplastic resins include ABS resin (a copolymer of acrylonitrile, butadiene, and styrene), polyolefins, polystyrene, and polycarbonate.

[0051] The two-component coating composition according to this disclosure is preferably an in-mold coating composition. The two-component coating composition according to this disclosure is suitable for in-mold coating because both the main component and the hardener have a solid content concentration of 95% by mass or more.

[0052] [Method for manufacturing coated molded articles] The method for manufacturing a coated molded article according to this disclosure preferably includes a step of applying a two-component coating composition according to this disclosure onto a resin molded article containing a thermoplastic resin to form a cured film.

[0053] Details of the thermoplastic resin are as described above.

[0054] The resin molded article may contain resins other than thermoplastic resins. The two-component coating composition according to this disclosure is for thermoplastic resins, and the resin molded article is preferably a molded article of a thermoplastic resin.

[0055] A resin molded article containing a thermoplastic resin can be obtained, for example, by molding a material containing a thermoplastic resin using any molding method.

[0056] The method for applying the two-component coating composition is not particularly limited and can be carried out by commonly known methods. A coating can be formed by applying the main component and the curing agent onto a resin molded article containing a thermoplastic resin. Furthermore, a cured film can be formed by curing the coating.

[0057] Unlike one-component coating compositions, two-component coating compositions have the advantage of not requiring consideration of pot life.

[0058] [Method for manufacturing in-mold coated molded articles] The method for manufacturing an in-mold coated molded article according to the present disclosure preferably includes the steps of: clamping a mold equipped with a fixed mold section and a movable mold section; molding a thermoplastic resin in the mold cavity to produce a resin molded article; injecting a two-component mold coating composition into the mold cavity to form a coating on the resin molded article; curing the coating to form a cured film; and removing the resin molded article with the cured film from the mold.

[0059] Alternatively, after molding a thermoplastic resin in a mold cavity to produce a resin molded body, the two-component coating composition may be injected into the mold cavity used for molding. Alternatively, after molding a thermoplastic resin in a first mold cavity to produce a resin molded body, the molded thermoplastic resin may be moved from the first mold cavity to a second mold cavity, and the two-component coating composition may be injected into the second mold cavity.

[0060] The following describes in detail the manufacturing method of the in-mold coated molded article according to this disclosure, including the configuration of the molding machine, the mold, and the paint composition injection device, with reference to the drawings. However, this disclosure is not limited to these specific embodiments.

[0061] Figure 1 is a diagram illustrating a method for manufacturing an in-mold coated molded body using injection molding.

[0062] In Figure 1, reference numeral 1 denotes a fixed platen of the mold clamping device of an injection molding machine, and reference numeral 2 denotes a movable platen. Both are equipped with a fixed mold section 3 and a movable mold section 4, which are mold members that face each other. The movable platen 2 is configured to move forward and backward by a mold clamping cylinder 5. A cavity 6 of a predetermined shape is formed in the fitting portion of the fixed mold section 3 and the movable mold section 4. Molten or softened thermoplastic resin is injected into this cavity 6, filled, and solidified.

[0063] The cavity 6 described above is configured to allow thermoplastic resin to be injected from an injection cylinder 7 having a screw, via a nozzle 8 and a sprue 9.

[0064] Furthermore, the system is equipped with an injector 10 with a shut-off pin 10A as a means for injecting the two-component coating composition (i.e., main agent and hardener), a metering cylinder 11 for supplying a predetermined amount of main agent to the injector 10, a supply pump 13 for supplying the main agent from the storage unit 12 to the metering cylinder 11, a metering cylinder 21 for supplying a predetermined amount of hardener to the injector 10, and a supply pump 23 for supplying the hardener from the storage unit 22 to the metering cylinder 21. The metering cylinder 11 is equipped with a plunger regulator 11A for main agent injection, and the metering cylinder 21 is equipped with a plunger regulator 21A for hardener injection.

[0065] During molding, the clamping cylinder 5 is first operated to close the fixed mold section 3 and the movable mold section 4, and clamping pressure is applied. The clamping pressure must be able to withstand the injection pressure of the thermoplastic resin. Typically, the injection pressure at the nozzle 8 is 40 MPa to 250 MPa. During this process, the supply pumps 13 and 23 are operated. The metering cylinder 11 is supplied with the required amount of main component. The metering cylinder 21 is supplied with the required amount of hardener.

[0066] Next, the thermoplastic resin in a molten or softened state is injected from the injection cylinder 7 into the cavity 6 via the nozzle 8 and sprue 9. When the thermoplastic resin has solidified in the mold to a degree that it can withstand the injection pressure and flow pressure of the paint composition, the clamping pressure is reduced, or the movable mold part 4 is retracted by a distance greater than the desired cured film thickness but without disengaging the fitting between the fixed mold part 3 and the movable mold part 4 (preferably 0.2 mm to 5 mm).

[0067] Next, the shut-off pin 10A is activated to open the injection port of the injector 10.

[0068] Next, the plunger regulator 11A for injecting the main component of the metering cylinder 11 and the plunger regulator 21A for injecting the hardener of the metering cylinder 21 are operated to inject enough of the main component and hardener to obtain the desired film thickness (preferably a cured film of 20 μm to 1,000 μm) between the cavity 6, i.e., the inner wall of the fixed mold section 3, and the surface of the molded resin body that covers the inside of the mold. After injecting the main agent and hardener, the injection port is closed again with the shut-off pin 10A. If necessary, the clamping cylinder 5 is operated to perform the clamping operation. The paint composition is spread within the mold to coat the surface of the resin molded body. This forms a film on the resin molded body. The film is partially cured or fully cured by heat within the cavity 6 to a degree that allows for demolding. Next, the clamping cylinder 5 is operated to separate the fixed mold section 3 and the movable mold section 4, and the molded body with a partially hardened or fully hardened cured film is removed from the mold.

[0069] The degree of partial or complete curing varies depending on factors such as the surface temperature of the fixed and movable mold sections, the time from injecting the thermoplastic resin into the mold to injecting the main component and hardener, the type of main component and hardener, and the holding time in the mold after injection of the main component and hardener. For example, the surface temperature of the fixed and movable mold sections is 90°C, the time from injecting the thermoplastic resin into the mold to injecting the main component and hardener is approximately 30 seconds, and the holding time in the mold after injection of the paint composition is approximately 3 minutes.

[0070] In the above embodiment, an example of manufacturing an in-mold coated molded body using injection molding was shown. However, in the process of manufacturing the resin molded body, thermoplastic resins may be molded using methods other than injection molding, such as injection compression molding, injection press molding, compression molding, or reaction injection molding.

[0071] [Coated molded body] The coated molded article according to this disclosure comprises a resin molded article containing a thermoplastic resin and a cured film formed on the resin molded article, wherein the cured film is a cured product of a main component and a curing agent in a two-component coating composition, the main component contains a polyamine and a polyol, has a solid content concentration of 95% by mass or more, does not contain a catalyst, or contains 0.25 parts by mass or less of a catalyst per 100 parts by mass of the total content of polyamine and polyol, and the curing agent contains a polyisocyanate, has a solid content concentration of 95% by mass or more.

[0072] Preferred embodiments of the resin molded article containing a thermoplastic resin and the two-component coating composition are as described above.

[0073] By forming a cured film on a resin molded article containing a thermoplastic resin using the two-component coating composition according to this disclosure, a cured film with excellent curability and adhesion can be obtained.

[0074] The thickness of the cured film is preferably 40 μm to 1000 μm, and more preferably 60 μm to 600 μm. The thickness of the cured film is measured by cutting the film in the thickness direction and using a microscope to analyze the cut surface. [Examples]

[0075] The present disclosure will be described in detail below with reference to examples. However, the present disclosure is not limited in any way by these examples.

[0076] <Preparation of the main ingredient> The main component was prepared by mixing each of the components listed in Tables 1 and 2 in the amounts (parts by mass) listed in Tables 1 and 2. Furthermore, the components listed in Tables 1 and 2 were used as curing agents. Details of each component are as follows: The content of each component in Table 1 is expressed as solid content.

[0077] -Main ingredient- (Polyamines) • Polyamine 1: Product name "Ancamide 506", manufactured by Evonik (amine equivalent 105) • Polyamine 2: Product name "EtaCure 420", manufactured by Mitsui Chemicals Fine Co., Ltd. (amine equivalent 78) • Polyamine 3: Product name "Polyetheramine D400", manufactured by Mitsui Chemicals Fine Co., Ltd. (amine equivalent 100)

[0078] (Polyol) • Polyol 1: Product name "Desmofen XP 2488", manufactured by Covestro. • Polyol 2: Product name "Desmofen VP LS 2249 / 1", manufactured by Covestro.

[0079] (catalyst) • Tin-containing compound 1: Product name "Neostan U-100", manufactured by Nitto Kasei Co., Ltd. • Bismuth-containing compound 1: Product name "K-KAT 348", manufactured by King Industries. • Bismuth-containing compound 2: Product name "K-KAT XK640", manufactured by King Industries.

[0080] (Additives) • UV absorber: Product name "Tinuvin400", manufactured by BASF. • Light stabilizer: Product name "Tinuvin123", manufactured by BASF. • Release agent: Product name "ZELEC UN", manufactured by Stepan.

[0081] -Hardening agent- (Polyisocyanate) • Polyisocyanate 1: Product name "Desmodulo Ultra N 3600 CAO", manufactured by Covestro. • Polyisocyanate 2: Product name "Desmodulo Ultra N 3900", manufactured by Covestro.

[0082] <Fabrication of molded products with in-mold coating> Using a mold with a cavity to obtain a box-shaped resin molded body with a length of 300 mm, a width of 200 mm, a height of 10 mm, and a plate thickness of 2.5 mm, the resin molded body was coated using the apparatus shown in Figure 1. The fixed mold section 3 was set to 80°C, the movable mold section 4 was set to 80°C, and the barrel temperature was heated to 250°C.

[0083] First, ABS resin (product name "TECHNO MUH(registered trademark) C7800", manufactured by Techno UMG Co., Ltd.) was heated and melted in injection cylinder 7, injected into a mold clamped at a clamping pressure of 100 MPa over approximately 1 second, and then cooled for 70 seconds. The resin molded body was solidified to a degree that could withstand the injection and flow pressure of the main agent and hardener.

[0084] Next, after separating the movable mold section 4 by approximately 0.4 mm, a total of 20 mL of the main agent and hardener was injected between the mold surface and the surface of the resin molded body over a period of approximately 1 second. The main agent and hardener were mixed by collision using a mixing head (injector 10) and injected into the sealed mold. An after-mixer was provided in the mold to improve mixing characteristics.

[0085] After injection was complete, the mold clamping pressure was increased to 2 MPa over 1 second and held for 30 minutes to cure the paint composition, after which the molded body with the in-mold coating was removed from the mold. The thickness of the cured film formed on the resin molded body was approximately 200 μm.

[0086] The obtained in-mold coated molded articles were evaluated for their curability, surface hardening properties, and adhesion.

[0087] <Curability> The state of the cured film on the obtained in-mold coated molded body was evaluated by touch after it was removed from the mold. A: Nothing sticks to your finger when you touch the hardened film. B: The hardened film will stick to your fingers when you touch it.

[0088] <Surface hardening> The resulting in-mold coated body was removed from the mold, allowed to cool for 30 minutes, and then the surface condition of the cured film was evaluated by touch and visual inspection. Surface hardening properties were evaluated in the following three stages. A: The hardened film has no sticky appearance, and nothing sticks to your fingers when you touch it. B: The hardened film looks sticky, but nothing sticks to your fingers when you touch it. C: The hardened film will stick to your fingers if you touch it.

[0089] <Adhesion> The obtained in-mold coated molded articles were subjected to adhesion tests in accordance with JIS K 5600-5-6:1999 (Adhesion (Cross-cut method)). The cut interval was 2 mm, and the appearance was visually evaluated by tape peeling tests at 100 grid points. A: The remaining cured film is 95% or more. B: The remaining cured film is between 65% and 95%. C: The remaining cured film is less than 65%.

[0090] The evaluation results are shown in Table 1.

[0091] [Table 1]

[0092] [Table 2]

[0093] As shown in Tables 1 and 2, Examples 1 to 10 contained a main component and a curing agent. The main component contained a polyamine and a polyol, with a solid content of 95% by mass or more, and either contained no catalyst or contained 0.25 parts by mass or less of catalyst per 100 parts by mass of the total content of polyamine and polyol. The curing agent contained a polyisocyanate, with a solid content of 95% by mass or more. As a result, the resulting coated molded articles exhibited excellent curability and adhesion. On the other hand, in Comparative Examples 1, 2, and 4, the catalyst content was more than 0.25 parts by mass per 100 parts by mass of the total content of polyamine and polyol, and it was found that the adhesion was poor. Comparative Example 3, which did not contain polyamine, was found to have inferior curability. [Explanation of Symbols]

[0094] 1 Fixed plate 2 Movable plate 3 Fixed mold section 4. Movable mold section Type 5 clamping cylinder 6 Cavity 7. Injection Cylinder 8 nozzles 9 Sprue 10 Injectors 10A Shut-off Pin 11, 21 Measuring Cylinder 11A, 21A plunger regulator 12, 22 Storage section 13, 23 Supply pumps

Claims

1. It has a main component and a hardening agent, The main ingredient is It contains polyamines and polyols. The solid content concentration is 95% by mass or higher. Either it does not contain a catalyst, or the catalyst content is 0.25 parts by mass or less per 100 parts by mass of the total content of the polyamine and the polyol. The aforementioned hardening agent is Contains polyisocyanate, The solid content concentration is 95% by mass or higher. A two-component coating composition for thermoplastic resins.

2. The two-component coating composition according to claim 1, which is an in-mold coating composition.

3. A method for manufacturing a coated molded article, comprising the step of applying the two-component coating composition described in claim 1 onto a resin molded article containing a thermoplastic resin to form a cured film.

4. A process of clamping a mold that has a fixed mold section and a movable mold section, The process involves molding thermoplastic resin in a mold cavity to produce a resin molded product, A step of injecting the two-component coating composition described in claim 2 into the mold cavity to form a coating on the resin molded body, The process of curing the aforementioned coating to form a cured film, The process of removing the resin molded body on which the cured film has been formed from the mold, A method for manufacturing an in-mold coated molded article, including the method described above.

5. A resin molded body containing a thermoplastic resin, and a cured film formed on the resin molded body, The cured film is a cured product of the main component and the curing agent in a two-component coating composition. The main component comprises a polyamine and a polyol, has a solid content concentration of 95% by mass or more, and contains no catalyst, or the catalyst content is 0.25 parts by mass or less per 100 parts by mass of the total content of the polyamine and the polyol. The curing agent is a coated molded article containing polyisocyanate and having a solid content concentration of 95% by mass or more.

6. The coated molded article according to claim 5, wherein the thickness of the cured film is 40 μm to 1000 μm.

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