Polyurethane resin-forming composition, coating agent set, coating film, and method for forming coating film

Abstract

A polyurethane resin-forming composition comprising: (A) a polyol; (B) a polyisocyanate; (C) an ultraviolet absorber; and (D) a hindered amine-based light stabilizer, wherein the component (A) includes a polycarbonate polyol, the component (C) includes a triazine-based ultraviolet absorber and / or an oxanilide-based ultraviolet absorber, and the content of volatile organic compounds is 0-5 mass%.

Description

Polyurethane resin-forming composition, coating agent set, coating film, and method for forming coating film

[0001] The present disclosure relates to a polyurethane resin-forming composition, a coating agent set, a coating film, and a method for forming a coating film.

[0002] A polyurethane resin-forming composition containing a polyol and a polyisocyanate is used as the coating agent. In recent years, from the viewpoint of reducing environmental impact, in-mold coating has attracted attention as a method for coating the surfaces of plastic molded products and the like (see, for example, Patent Document 1). The in-mold coating method is a method in which a substrate is placed in a mold such as a metal mold, and a coating agent is injected into the mold and reacted to form a coating film on the surface of the substrate. This method allows the mold used to mold the substrate to be used as the coating mold, so it is possible to coat the surface of the substrate with fewer steps than conventional coating methods, and it is possible to reduce the amount of waste generated and energy consumption associated with the coating process.

[0003] Japanese Patent Application Laid-Open No. 2005-074896

[0004] Polyurethane resin-forming compositions used in coating agents for in-mold coating are used, for example, to paint plastic molded products used in automobile interior and exterior parts, etc. In such applications, it is required that the coating film exhibits little deterioration in surface gloss and little yellowing due to the influence of the usage environment, such as light, temperature, and humidity, i.e., that the coating film has excellent weather resistance.

[0005] Therefore, an object of one aspect of the present disclosure is to provide a polyurethane resin-forming composition that can be used as a coating agent for in-mold coating and that forms a coating film with excellent weather resistance when applied in-mold.

[0006] Some aspects of the present disclosure provide the following [1] to

[13] .

[0007] [1] A polyurethane resin-forming composition comprising: (A) a polyol; (B) a polyisocyanate; (C) an ultraviolet absorber; and (D) a hindered amine-based light stabilizer, wherein the component (A) comprises a polycarbonate polyol; the component (C) comprises at least one of a triazine-based ultraviolet absorber and an oxalic acid anilide-based ultraviolet absorber; and the content of volatile organic compounds is 0 to 5 mass %.

[0008] [2] The polyurethane resin-forming composition according to [1], wherein the average hydroxyl value of the component (A) is 300 to 800 mgKOH / g.

[0009] [3] The polyurethane resin-forming composition according to [1] or [2], wherein the content of the polycarbonate polyol is 30 mass% or more based on the total mass of the component (A).

[0010] [4] The polyurethane resin-forming composition according to any one of [1] to [3], wherein the component (C) contains a triazine-based ultraviolet absorber.

[0011] [5] The polyurethane resin-forming composition according to [4], wherein the triazine-based ultraviolet absorber includes a compound represented by the following formula (C-2): [In formula (C-2), R １１ represents an alkyl group having 1 to 15 carbon atoms, and R ２ ~R ５ each independently represents a hydrogen atom, a hydroxyl group, a methyl group, or an ethyl group.

[0012] [6] The polyurethane resin-forming composition according to any one of [1] to [5], wherein the molecular weight of the component (D) is less than 1,000.

[0013] [7] The polyurethane resin-forming composition according to any one of [1] to [6], wherein the component (D) includes a compound having a structure represented by the following formula (D-2): [In formula (D-2), * represents a bond.]

[0014] [8] The polyurethane resin-forming composition according to any one of [1] to [7], wherein the content of the component (D) is 0.05 parts by mass or more per 100 parts by mass of the total content of the components (A) and (B).

[0015] [9] The polyurethane resin-forming composition according to any one of [1] to [8], wherein the total content of the component (C) and the component (D) is 0.5 parts by mass or more per 100 parts by mass of the total content of the component (A) and the component (B).

[0016]

[10] The polyurethane resin-forming composition according to any one of [1] to [9], which is used as a coating agent for coating inside a mold.

[0017]

[11] A coating agent set for preparing the polyurethane resin-forming composition according to any one of [1] to

[10] , comprising: a first agent containing the component (A), the component (C), and the component (D); and a second agent containing the component (B).

[0018]

[12] A coating film comprising a reaction product of the composition according to any one of [1] to

[10] .

[0019]

[13] A method for forming a coating film, comprising: preparing a substrate and a mold with the substrate disposed therein; injecting the composition according to any one of [1] to

[10] into the mold and applying the composition to a surface of the substrate; and reacting the composition to form a coating film on the surface of the substrate.

[0020] According to one aspect of the present disclosure, it is possible to provide a polyurethane resin-forming composition that can be used as a coating agent for in-mold coating and that forms a coating film with excellent weather resistance when applied in-mold.

[0021] 1 is a schematic diagram for explaining an embodiment of an in-mold coating method of the present disclosure. FIG.

[0022] Hereinafter, several embodiments of the present disclosure will be described, but the present disclosure is not limited to the following embodiments.

[0023] In this specification, a numerical range indicated using "to" indicates a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. Furthermore, unless otherwise specified, the units of the numerical values ​​before and after "to" are the same. In the numerical ranges described in stages in this specification, the upper or lower limit of a certain numerical range may be replaced with the upper or lower limit of a numerical range of another stage. Furthermore, in the numerical ranges described in this specification, the upper or lower limit of that numerical range may be replaced with a value shown in the examples. Furthermore, the upper and lower limits individually described can be arbitrarily combined. Unless otherwise specified, the materials exemplified below may be used alone or in combination of two or more types. When multiple substances corresponding to each component are present in the composition, the content of each component in the composition means the total amount of the multiple substances present in the composition, unless otherwise specified.

[0024] <Polyurethane Resin-Forming Composition> One embodiment of the present disclosure relates to a polyurethane resin-forming composition (hereinafter simply referred to as the "composition") containing (A) a polyol (hereinafter also referred to as "component (A)"), (B) a polyisocyanate (hereinafter also referred to as "component (B)"), (C) an ultraviolet absorber (hereinafter also referred to as "component (C)"), and (D) a hindered amine-based light stabilizer (hereinafter also referred to as "component (D)"), wherein component (A) comprises a polycarbonate polyol, component (C) comprises at least one of a triazine-based ultraviolet absorber and an oxalic acid anilide-based ultraviolet absorber, and the volatile organic compound content (based on the total mass of the composition) is 0 to 5 mass%. Here, "polyurethane resin-forming ability" means having the property of being able to form a polyurethane resin. The composition contains component (A) and component (B), and a polyurethane resin can be formed by reaction between component (A) and component (B). Furthermore, the term "volatile organic compound" refers to an organic compound having a boiling point of 180° C. or less at 1 atm.

[0025] The composition allows for the formation of a coating film with excellent weather resistance through in-mold coating. Specifically, the coating film formed by the composition is less susceptible to deterioration in surface gloss and yellowing due to the influence of the usage environment, such as light, temperature, and humidity. Therefore, even when used to paint parts requiring weather resistance (e.g., plastic molded products used for automotive interior and exterior parts), good surface gloss and low b* can be maintained. Therefore, the composition is suitable for use as a coating agent for in-mold coating (in-mold coating agent), and is particularly suitable for use as a coating agent for plastic molded products used for automotive interior and exterior parts.

[0026] In general coating agents, volatile organic compounds are used as solvents to dissolve additives. However, in in-mold coating methods, the mold is an enclosed space, and the use of solvents (volatile organic compounds) is restricted to prevent poor coating film formation due to air bubbles and other factors. Therefore, when additives are used in coating agents for in-mold coating, energy such as thermal energy is required to dissolve the additives and suppress their precipitation, resulting in increased energy consumption during preparation and storage. On the other hand, the above composition allows the additives (components (C) and (D)) to dissolve easily in component (A), and can be prepared at relatively low temperatures (e.g., below 100°C). Furthermore, the above composition is unlikely to precipitate at typical storage temperatures (e.g., 0 to 50°C) and has excellent low-temperature stability. Therefore, the above composition tends to reduce energy consumption during preparation and storage.

[0027] Furthermore, the composition can easily develop the self-repairing properties of the coating film. That is, the coating film formed by the composition also tends to have excellent self-repairing properties. Although the self-repairing properties of the coating film are not necessarily required, the coating film may have self-repairing properties in applications for plastic molded products used in interior and exterior parts of automobiles, etc. The self-repairing properties may be impaired by the influence of the usage environment, such as light, temperature, and humidity, but it is also possible to suppress the deterioration of the self-repairing properties by adjusting the content of the (C) component, for example.

[0028] Components that can be contained in the polyurethane resin-forming composition will be described below.

[0029] [Component (A): Polyol] A polyol is a compound having multiple hydroxyl groups (—OH). As component (A), one type of polyol may be used alone, or two or more types of polyols may be used in combination.

[0030] From the viewpoint of achieving superior film-forming properties during in-mold coating, component (A) may be liquid at 25° C. In this specification, "liquid at 25° C." means that when heated to 80° C. or higher, allowed to stand at 25° C. for 24 hours, and then tilted, even a slight degree of fluidity can be confirmed by visual observation.

[0031] Component (A) includes a polycarbonate polyol. A polycarbonate polyol is a compound having multiple hydroxyl groups (—OH) and multiple carbonate groups (—OCOO—). A polycarbonate polyol is, for example, a reaction product of a polyol component (hereinafter also referred to as “component (a1)”) and a carbonate component (hereinafter also referred to as “component (a2)”), and includes component (a1) and component (a2) as monomer units.

[0032] The polycarbonate polyol may be a non-aromatic polycarbonate polyol from the viewpoint of obtaining better transparency. In this specification, "non-aromatic polycarbonate polyol" means a polycarbonate polyol that does not have an aromatic ring (for example, a benzene ring).

[0033] The component (a1) may contain a glycol. A glycol is a compound having a structure in which one hydroxyl group is substituted for every two carbon atoms of a chain aliphatic hydrocarbon or a cyclic aliphatic hydrocarbon. Examples of glycols include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,1 ...17-hexanediol, 1,18-hexanediol, 1,19-hexanediol, 1,20-hexanediol, 1,21-hexanediol, 1,22-hexanediol, 1,23-hexanediol, 1,24-hexanediol, 1,25-hexanediol, 1,26-hexanediol, 1,27-hexanediol, 1,28-hexanediol, 1,29-hexanediol, 1,30-hexanediol, 1,31-hexanediol, 1,32-hexanediol, 1,33-hexanediol, 1,34-hexanediol, 1,35-hexanediol, 1,36-hexanediol, 1,37-hexanediol and branched glycols such as 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 1,3-butanediol, 3-methyl-1,5-pentanediol, 1,4-cyclohexanediol, 2-methyl-1,8-octanediol, 1,12-octadecanediol, etc. When component (a1) contains some of these glycols alone or a specific combination of several glycols, the polycarbonate polyol is liquid at 25°C.

[0034] The lower the crystallinity of the (a1) component, the more likely the polycarbonate polyol is to become liquid at 25°C. Furthermore, when two or more (a1) components are used in combination, the polycarbonate polyol is more likely to become liquid at 25°C, and when three or more (a1) components are used in combination, the more likely it is to become liquid at 25°C. Furthermore, when two or more (a1) components are used in combination, the smaller the ratio (mass ratio) of the linear single component, the more likely the polycarbonate polyol is to become liquid at 25°C. For example, when two linear glycols are used in combination, the closer the ratio (mass ratio) of the two glycols is to 1:1, the more likely the polycarbonate polyol is to become liquid at 25°C. Furthermore, when two or more (a1) components are used in combination, the polycarbonate polyol is more likely to become liquid at 25°C when it contains an (a1) component with a short carbon chain (for example, an (a1) component with 6 or less carbon atoms) and / or a branched (a1) component.

[0035] For example, when component (a1) contains at least one selected from the group consisting of 1,3-butanediol, 3-methyl-1,5-pentanediol, and 2-methyl-1,8-octanediol, and a linear glycol having 3 to 6 carbon atoms (i.e., when the polycarbonate polyol contains, as monomer units, at least one selected from the group consisting of 1,3-butanediol, 3-methyl-1,5-pentanediol, and 2-methyl-1,8-octanediol, and a linear glycol having 3 to 6 carbon atoms), the polycarbonate polyol tends to be liquid at 25°C.

[0036] Furthermore, for example, when component (a1) contains at least two types of linear glycols having 3 to 6 carbon atoms (i.e., when the polycarbonate polyol contains at least two types of linear glycols having 3 to 6 carbon atoms as monomer units), the polycarbonate polyol tends to become liquid at 25°C.

[0037] From the viewpoint of further improving the mechanical properties of the coating film and forming a harder coating film, component (a1) may contain a polyol having three or more hydroxyl groups. The polyol having three or more hydroxyl groups may be used in combination with at least one member selected from the group consisting of 1,3-butanediol, 3-methyl-1,5-pentanediol, and 2-methyl-1,8-octanediol, and / or a linear glycol having 3 to 6 carbon atoms. The polyol having three or more hydroxyl groups is, for example, a non-aromatic polyol that does not have an aromatic ring. Specific examples of polyols having three or more hydroxyl groups include trimethylolethane, trimethylolpropane, 2-hydroxy-2-methyl-1,4-butanediol, glycerin, ditrimethylolethane, ditrimethylolpropane, diglycerin, pentaerythritol, xylitol, dipentaerythritol, sorbitol, and 1,3,5-tris(hydroxymethyl)benzene.

[0038] The content of the polyol having three or more hydroxyl groups in component (a1) is 0% by mass or more, and from the viewpoint of further improving the mechanical properties of the coating film, it may be 5% by mass or more, 10% by mass or more, or 15% by mass or more. From the viewpoint of compatibility of the composition and further improving the self-repairing properties of the coating film, it may be 45% by mass or less, 35% by mass or less, or 30% by mass or less. From these viewpoints, the content of the polyol having three or more hydroxyl groups may be 0 to 45% by mass, 5 to 45% by mass, 10 to 35% by mass, or 15 to 30% by mass. Note that the above content is the content based on the total mass of component (a1).

[0039] The component (a2) may be any compound capable of condensing with a polyol to produce a polycarbonate polyol. Examples of the component (a2) include dialkyl carbonates such as dimethyl carbonate, diethyl carbonate, and dipropyl carbonate, alkylene carbonates such as ethylene carbonate and propylene carbonate, and diaryl carbonates such as diphenyl carbonate, dinaphthyl carbonate, dianthryl carbonate, diphenanthryl carbonate, diindanyl carbonate, and bistetrahydronaphthyl carbonate. These may be used alone or in combination of two or more.

[0040] The polycarbonate polyol may be a reaction product obtained by reacting the reaction product of the (a1) component and the (a2) component, or the (a1) component and the (a2) component, with another reaction component (e.g., a polyester polyol) in the presence of a catalyst. When the other component is a polyester polyol, the polycarbonate polyol can be called a polyester polycarbonate polyol. The polyester polycarbonate polyol contains the (a1) component and the (a2) component as monomer units and also contains an ester skeleton derived from the polyester polyol.

[0041] Examples of other reaction components include cyclic esters such as ε-caprolactone, polycaprolactone oligomers, etc. These may be used alone or in combination of two or more. The amount of the other reaction components may be, for example, 0 to 40 parts by mass, 5 to 35 parts by mass, or 10 to 30 parts by mass relative to 100 parts by mass of the polycarbonate polyol.

[0042] The hydroxyl value of the polycarbonate polyol may be, for example, 100 to 400 mgKOH / g. When the hydroxyl value of the polycarbonate polyol is within the above range, the low-temperature processability of the composition is improved, and the appearance of the coating film formed in the in-mold coating method is likely to be better. From the viewpoints of further improving the low-temperature processability of the composition, increasing the compatibility of the composition, and further improving the coating film formability, the hydroxyl value of the polycarbonate polyol may be 150 mgKOH / g or more or 200 mgKOH / g or more. From the viewpoint of forming a coating film with better mechanical properties, the hydroxyl value of the polycarbonate polyol may be 380 mgKOH / g or less or 350 mgKOH / g or less. From these viewpoints, the hydroxyl value of the polycarbonate polyol may be 150 to 380 mgKOH / g or 200 to 350 mgKOH / g.

[0043] In this specification, the hydroxyl value means the number of milligrams (mg) of potassium hydroxide equivalent to the hydroxyl groups in 1 g of sample, and is measured in accordance with JIS K1557-1.

[0044] The molecular weight of the polycarbonate polyol may be, for example, 200 or more. From the viewpoint of easily obtaining a coating film having better mechanical properties, the molecular weight of the polycarbonate polyol may be 300 or more, 400 or more, or 450 or more. From the viewpoint of further improving the low-temperature processability of the composition, increasing the compatibility of the composition, and further improving the coating film formability, the molecular weight of the polycarbonate polyol may be 1100 or less, 1000 or less, or 800 or less. From these viewpoints, the molecular weight of the polycarbonate polyol may be 200 to 1100, 300 to 1000, or 400 to 800.

[0045] In this specification, the molecular weight is a molecular weight measured using gel permeation chromatography (for example, a converted molecular weight using a calibration curve of polycarbonate diol made of 1,6-hexanediol), but it can also be calculated from the hydroxyl value and the number of hydroxyl groups (theoretical value).

[0046] The polycarbonate polyol can be obtained, for example, by reacting component (a1) with component (a2) in the presence of a catalyst such as tetrabutoxytitanium. The reaction may be carried out, for example, in a reaction apparatus equipped with a stirrer, thermometer, heater, and distillation column under a nitrogen stream. Specifically, for example, the temperature is gradually increased to 190°C under a nitrogen stream while distilling off ethanol, and the pressure is gradually reduced to 0.5 kPa or less. The reaction is carried out at a pressure of 0.5 kPa or less for 4 hours or more, thereby obtaining a polycarbonate polyol as a reaction product of component (a1) and component (a2). The blending ratio of each component may be appropriately adjusted, for example, from the viewpoint of the hydroxyl value.

[0047] The component (A) may consist solely of polycarbonate polyol, or may contain, in addition to the polycarbonate polyol, a polyol other than the polycarbonate polyol. From the viewpoints of obtaining better weather resistance and making additives less likely to precipitate at low temperatures (improving low-temperature stability), the content of the polycarbonate polyol may be 30% by mass or more, 50% by mass or more, or 60% by mass or more, based on the total mass of the component (A). From the viewpoint of obtaining better weather resistance, the content of the polycarbonate polyol in the component (A) may be 90% by mass or less, 85% by mass or less, or 80% by mass or less, based on the total mass of the component (A). From the above viewpoints, the content of the polycarbonate polyol may be 30 to 90% by mass, 50 to 85% by mass, or 60 to 80% by mass, based on the total mass of the component (A).

[0048] As the polyol other than the polycarbonate polyol, a polyol having a molecular weight of less than 200 (hereinafter referred to as a "low molecular weight polyol") may be used. The molecular weight of the low molecular weight polyol may be, for example, 50 or more and less than 200, or may be 60 to 180 or 70 to 150.

[0049] The low-molecular-weight polyol may be a diol or a polyol having three or more hydroxyl groups. When the low-molecular-weight polyol contains a diol, a coating film having better self-repairing properties is more likely to be obtained, and the effects of improving the compatibility of the composition and further enhancing the coating film formability due to lower viscosity are obtained. When the low-molecular-weight polyol contains a triol, a coating film having better mechanical properties is more likely to be obtained. From these viewpoints, the low-molecular-weight polyol may contain a diol and / or a triol, and from the viewpoint of achieving a higher level of both the self-repairing properties and the mechanical properties of the coating film, it may contain a diol and a triol.

[0050] Examples of diols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 2-methyl-1,3-propanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, dimethylolheptane, diethylene glycol, dipropylene glycol, neopentyl glycol, diethylene glycol, dipropylene glycol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, dimer diol, etc. 1,3-butanediol and 2-methyl-1,3-propanediol may be used from the viewpoints of easily obtaining a coating film having superior self-repairing properties, improving the compatibility of the composition, and further enhancing the coating film formability by reducing viscosity. The above diols may be used alone or in combination of two or more kinds.

[0051] The content of the diol may be 5 to 55 mass %, 10 to 50 mass %, or 15 to 40 mass %, based on the total mass of component (A), from the viewpoints of easily obtaining a coating film with better self-repairing properties, and of obtaining the effect of improving the compatibility of the composition and the effect of further enhancing the coating film formability by reducing the viscosity.

[0052] Examples of triols include trimethylolethane, trimethylolpropane, 2-hydroxy-2-methyl-1,4-butanediol, glycerin, ditrimethylolethane, ditrimethylolpropane, diglycerin, and pentaerythritol. Trimethylolpropane may be used from the viewpoint of facilitating the formation of a harder coating film and facilitating the production of a coating film having better mechanical properties. The above triols may be used alone or in combination of two or more.

[0053] From the viewpoint of facilitating the formation of a harder coating film and facilitating the production of a coating film having better mechanical properties, the content of the triol may be 1 to 30 mass%, 3 to 20 mass%, or 5 to 10 mass%, based on the total mass of component (A). The content of the triol may also be 0 to 30 mass%, based on the total mass of component (A).

[0054] From the viewpoint of suppressing a decrease in self-repairing property and a decrease in curing property, the content of the low-molecular-weight polyol may be 10 to 70% by mass, 15 to 50% by mass, or 20 to 40% by mass, based on the total mass of the component (A).

[0055] From the viewpoint of achieving better weather resistance (particularly gloss retention), the average hydroxyl value of component (A) may be 300 mgKOH / g or more, 400 mgKOH / g or more, or 500 mgKOH / g or more. From the viewpoint of making it more difficult for additives to precipitate at low temperatures (improving low-temperature stability), the average hydroxyl value of component (A) may be 800 mgKOH / g or less, 700 mgKOH / g or more, or 600 mgKOH / g or more. From these viewpoints, the average hydroxyl value of component (A) may be 300 to 800 mgKOH / g, 400 to 700 mgKOH / g, or 500 to 600 mgKOH / g. The average hydroxyl value of component (A) is a weighted average of the hydroxyl values ​​weighted by the masses of the various polyols contained in component (A), and is determined by multiplying the hydroxyl values ​​of the various polyols by their respective masses to obtain the sum, and then dividing the sum by the mass of component (A) (the sum of the masses of the various polyols).

[0056] From the viewpoint of obtaining better weather resistance, the average number of hydroxyl groups of component (A) may be 2.0 to 3.0, or alternatively 2.0 to 2.5, or 2.0 to 2.3. The average number of hydroxyl groups of component (A) is a weighted average of the numbers of hydroxyl groups weighted by the amounts of substance of the various polyols contained in component (A), and is determined by multiplying the numbers of hydroxyl groups of the various polyols by their respective amounts of substance to obtain the sum, and then dividing the sum by the amount of substance of component (A) (the sum of the amounts of substance of the various polyols).

[0057] The content of the component (A) may be, for example, 10 to 80 mass %, 20 to 70 mass %, or 30 to 60 mass %, based on the total mass of the composition.

[0058] [Component (B): Polyisocyanate] Polyisocyanate is a compound having multiple isocyanate groups (-NCO). As component (B), one type of polyisocyanate may be used alone, or two or more types of polyisocyanates may be used in combination.

[0059] From the viewpoint of achieving superior coating film forming properties during in-mold coating, component (B) may be liquid at 25°C.

[0060] From the viewpoint of further improving the weather resistance (particularly yellowing resistance) of the coating film, component (B) may contain a non-aromatic polyisocyanate. In this specification, "non-aromatic polyisocyanate" means a polyisocyanate that does not have an aromatic ring (for example, a benzene ring).

[0061] Examples of non-aromatic polyisocyanates include aliphatic polyisocyanates, alicyclic polyisocyanates, and modified products thereof, such as isocyanurate-modified products, allophanate-modified products, biuret-modified products, urethane-modified products, urea-modified products, carbodiimide-modified products, uretonimine-modified products, and uretdione-modified products.

[0062] Examples of aliphatic polyisocyanates include hexamethylene diisocyanate, tetramethylene diisocyanate, 2-methylpentane-1,5-diisocyanate, 3-methylpentane-1,5-diisocyanate, lysine diisocyanate, trioxyethylene diisocyanate, ethylene diisocyanate, trimethylene diisocyanate, octamethylene diisocyanate, nonamethylene diisocyanate, 2,2'-dimethylpentane diisocyanate, 2,2,4-trimethylhexane diisocyanate, decamethylene diisocyanate, butene diisocyanate, 1,3-butadiene-1,4-diisocyanate, and 2,4,4-trimethylhexane diisocyanate. Examples of such isocyanates include ethylene diisocyanate, 1,6,11-undecane triisocyanate, 1,3,6-hexamethylene triisocyanate, 1,8-diisocyanate-4-isocyanate methyl octane, 2,5,7-trimethyl-1,8-diisocyanate-5-isocyanate methyl octane, bis(isocyanate ethyl)carbonate, bis(isocyanate ethyl)ether, 1,4-butylene glycol dipropyl ether-α,α'-diisocyanate, lysine diisocyanate methyl ester, 2-isocyanate ethyl-2,6-diisocyanate hexanoate, 2-isocyanate propyl-2,6-diisocyanate hexanoate, etc. These may be used alone or in combination of two or more.

[0063] Examples of alicyclic polyisocyanates include isophorone diisocyanate, cyclohexyl diisocyanate, bis(isocyanatomethyl)cyclohexane, dicyclohexylmethane diisocyanate, methylcyclohexane diisocyanate, dicyclohexyldimethylmethane diisocyanate, 2,2'-dimethyldicyclohexylmethane diisocyanate, bis(4-isocyanato-n-butylidene)pentaerythritol, and hydrogenated dimer acid diisocyanate. , 2-isocyanatomethyl-3-(3-isocyanatopropyl)-5-isocyanatomethyl-bicyclo[2.2.1]-heptane, 2-isocyanatomethyl-3-(3-isocyanatopropyl)-6-isocyanatomethyl-bicyclo[2.2.1]-heptane, 2-isocyanatomethyl-2-(3-isocyanatopropyl)-5-isocyanatomethyl-bicyclo[2.2.1]-heptane, 2-isocyanatomethyl-2-(3-isocyanatopropyl 2-isocyanatomethyl-3-(3-isocyanatopropyl)-5-(2-isocyanatoethyl)-bicyclo[2.2.1]-heptane, 2-isocyanatomethyl-3-(3-isocyanatopropyl)-6-(2-isocyanatoethyl)-bicyclo[2.2.1]-heptane, 2-isocyanatomethyl-2-(3-isocyanatopropyl)-5-(2-isocyanatoethyl) 2-isocyanatemethyl-2-(3-isocyanatepropyl)-6-(2-isocyanateethyl)-bicyclo-[2.2.1]-heptane, 2,5-bis(isocyanatemethyl)-bicyclo[2.2.1]-heptane, hydrogenated diphenylmethane diisocyanate, norbornane diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylene diisocyanate, hydrogenated tetramethylxylene diisocyanate, etc. These may be used alone or in combination of two or more.

[0064] Among the above-mentioned polyisocyanates, when component (B) contains at least one selected from the group consisting of an isocyanurate of an aliphatic diisocyanate and an allophanate of an aliphatic diisocyanate, the balance between film formability during in-mold coating (e.g., film formability during in-mold coating at low temperatures) and curability (e.g., low-temperature rapid curing) tends to be improved. In particular, when component (B) contains an isocyanurate-modified aliphatic diisocyanate, the curability (e.g., low-temperature rapid curing) tends to be improved, and when component (B) contains an allophanate-modified aliphatic diisocyanate, the film formability during in-mold coating (e.g., film formability during in-mold coating at low temperatures) tends to be improved. From these viewpoints, the above-mentioned isocyanurate-modified product and the above-mentioned allophanate-modified product may be used in combination.

[0065] The content of the isocyanurate-modified product in the component (B) may be 10% by mass or more, 30% by mass or more, 50% by mass or more, 70% by mass or more, or 90% by mass or more, and may be 100% by mass or less, 90% by mass or less, 70% by mass or less, 50% by mass or less, 30% by mass or less, or 0 to 100% by mass, 10 to 90% by mass, or 30 to 70% by mass. The above content is based on the total mass of the component (B).

[0066] The content of the allophanate-modified product in component (B) may be 10% by mass or more, 30% by mass or more, 50% by mass or more, 70% by mass or more, or 90% by mass or more, and may be 100% by mass or less, 90% by mass or less, 70% by mass or less, 50% by mass or less, 30% by mass or less, or 0 to 100% by mass, 10 to 90% by mass, or 30 to 70% by mass. The above content is based on the total mass of component (B).

[0067] The NCO content of component (B) may be 10 to 40% by mass, 15 to 35% by mass, or 19 to 30% by mass. When the NCO content of component (B) is 10% by mass or more, the coating film tends to have higher hardness. When the NCO content of component (B) is 40% by mass or less, the coating film tends to exhibit good self-repairing properties. The above contents are based on the total mass of component (B).

[0068] In this specification, the NCO content is a value measured by the method described in JIS K1603-1 (Testing method for aromatic isocyanates used as raw materials for polyurethanes).

[0069] The content of the component (B) may be, for example, 20 to 90 mass %, 30 to 80 mass %, or 40 to 70 mass %, based on the total mass of the composition.

[0070] [Component (C): UV absorber] The UV absorber is an additive that has the function of absorbing UV rays. The component (C) contains at least one of a triazine-based UV absorber and an oxalic acid anilide-based UV absorber. The component (C) may contain only one of a triazine-based UV absorber and an oxalic acid anilide-based UV absorber, or may contain both a triazine-based UV absorber and an oxalic acid anilide-based UV absorber. From the viewpoint of achieving better solubility in the component (A), the component (C) may contain a triazine-based UV absorber.

[0071] As the triazine-based ultraviolet absorber, a wide variety of known triazine-based ultraviolet absorbers used in the field of resin materials can be used. From the viewpoints of achieving superior solubility in component (A) and superior weather resistance, a compound represented by the following formula (C-1) may be used.

[0072] In formula (C-1), R １ represents a hydrocarbon group having 1 to 15 carbon atoms, and R ２ ~R ５ R each independently represents a hydrogen atom, a hydroxyl group, a methyl group, or an ethyl group. １ The hydrogen atoms of the hydrocarbon group represented by the formula (R) may be substituted with a hydroxyl group or an alkoxy group having 1 to 15 carbon atoms. ２ ~R ５ may be a hydrogen atom, a methyl group, or an ethyl group, or may be a methyl group or an ethyl group, or may be a methyl group. The effect of improving solubility and weather resistance tends to increase in the order of hydrogen atom, ethyl group, and methyl group.

[0073] R １The hydrocarbon group represented by the formula (I) may be, for example, an alkyl group. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a t-butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a 2-ethylhexyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tetradecyl group, and a pentadecyl group. The hydrogen atoms of these alkyl groups may be substituted with hydroxyl groups or alkoxy groups having 1 to 15 carbon atoms. Examples of the alkoxy group having 1 to 15 carbon atoms include a methoxy group, an ethoxy group, a propyloxy group, an isopropyloxy group, a butyloxy group, an isobutyloxy group, a t-butyloxy group, a pentyloxy group, a hexyloxy group, a heptyloxy group, an octyloxy group, a 2-ethylhexyloxy group, a nonyloxy group, a decyloxy group, an undecyloxy group, a dodecyloxy group, a tetradecyloxy group, and a pentadecyloxy group.

[0074] The triazine-based ultraviolet absorber may contain a compound represented by the following formula (C-2), from the viewpoint of improving solubility in the component (A) and making precipitation at low temperatures less likely to occur (improving low-temperature stability).

[0075] In formula (C-2), R １１ represents an alkyl group having 1 to 15 carbon atoms. ２ ~R ５ is R in formula (C-1) ２ ~R ５ It is synonymous with R １１ Examples of the alkyl group represented by R include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a t-butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a 2-ethylhexyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tetradecyl group, and a pentadecyl group. １１ The alkyl group represented by the following formula may be a methyl group, from the viewpoint of further improving the solubility in the component (A) and the low-temperature stability.

[0076] Specific examples of triazine-based ultraviolet absorbers include 2-[4-[(2-hydroxy-3-(2'-ethyl)hexyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine (Tinuvin 405 manufactured by BASF), 2-(4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine-2-yl)-5-(octyloxy)phenol, 2-[4-[(2-hydroxy-3-dodecyloxypropyl)oxy]-2-hydroxyphenyl]-4,6- Examples include a mixture of bis(2,4-dimethylphenyl)-1,3,5-triazine and 2-[4-[(2-hydroxy-3-tridecyloxypropyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine (Tinuvin 400 manufactured by BASF), and 2-[4-[4,6-bis(biphenyl-4-yl)-1,3,5-triazin-2-yl]-3-hydroxyphenoxy]propane 6-methylheptyl (Tinuvin 479 manufactured by BASF).

[0077] From the viewpoint of achieving better weather resistance (particularly yellowing resistance), the content of the triazine-based ultraviolet absorber may be 0.05 parts by mass or more per 100 parts by mass of the total content of the (A) and (B) components. From the viewpoint of achieving better mechanical properties, the content of the triazine-based ultraviolet absorber may be 0.05 to 5 parts by mass per 100 parts by mass of the total content of the (A) and (B) components. From the same viewpoint as above, the content of the triazine-based ultraviolet absorber may be 0.1 parts by mass or more, or 0.2 parts by mass or more, or 3 parts by mass or less, or 1 part by mass or less, or 0.1 to 3 parts by mass, or 0.1 to 1 part by mass, per 100 parts by mass of the total content of the (A) and (B) components.

[0078] As the oxalic acid anilide-based ultraviolet absorber, a wide variety of known oxalic acid anilide-based ultraviolet absorbers used in the field of resin materials can be used. From the viewpoints of obtaining superior solubility in component (A) and superior weather resistance, a compound represented by the following formula (C-3) may be used.

[0079] In formula (C-3), R ６ represents an alkyl group having 1 to 15 carbon atoms, and R ７ and R ８ represents a hydrogen atom, and the other represents an alkyl group having 1 to 15 carbon atoms.

[0080] R ６ ~R ８ Examples of the alkyl group represented by the formula (I) include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a t-butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a 2-ethylhexyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tetradecyl group, and a pentadecyl group.

[0081] Specific examples of oxalic acid anilide-based ultraviolet absorbers include 2-ethoxy-2'-ethyl oxalic acid bisanilide (HOSTAVIN VSU, manufactured by Clariant Chemicals Co., Ltd.), 2-ethoxy-3'-dodecyl oxalic acid bisanilide (HOSTAVIN 3206, manufactured by Clariant Chemicals Co., Ltd.), and the like.

[0082] From the viewpoint of achieving better weather resistance (particularly yellowing resistance), the content of the oxalic acid anilide ultraviolet absorber may be 0.05 parts by mass or more per 100 parts by mass of the total content of the (A) and (B) components. From the viewpoint of achieving better mechanical properties, the content of the oxalic acid anilide ultraviolet absorber may be 0.05 to 5 parts by mass per 100 parts by mass of the total content of the (A) and (B) components. From the same viewpoint as above, the content of the oxalic acid anilide ultraviolet absorber may be 0.1 parts by mass or more, or 0.2 parts by mass or more, or 3 parts by mass or less, or 1 part by mass or less, or 0.1 to 3 parts by mass, or 0.1 to 1 part by mass, per 100 parts by mass of the total content of the (A) and (B) components.

[0083] The component (C) may contain an ultraviolet absorber other than a triazine-based ultraviolet absorber and an oxalic acid anilide-based ultraviolet absorber. From the viewpoint of achieving better solubility in the component (A) and better weather resistance, the content of ultraviolet absorbers other than a triazine-based ultraviolet absorber and an oxalic acid anilide-based ultraviolet absorber in the component (C) may be 50% by mass or less, 1% by mass or less, or 0.1% by mass or less, based on the total mass of the component (C).

[0084] From the viewpoint of achieving better weather resistance (particularly yellowing resistance), the content of the (C) component may be 0.05 parts by mass or more per 100 parts by mass of the total content of the (A) component and the (B) component. From the viewpoint of achieving better mechanical properties, the content of the (C) component may be 5 parts by mass or less per 100 parts by mass of the total content of the (A) component and the (B) component. From these viewpoints, the content of the (C) component may be 0.05 to 5 parts by mass per 100 parts by mass of the total content of the (A) component and the (B) component. From the same viewpoints as above, the content of the (C) component may be 0.1 parts by mass or more, or 0.2 parts by mass or more, and may be 3 parts by mass or less, 1 part by mass or less, or 0.1 to 3 parts by mass, or 0.2 to 1 part by mass, per 100 parts by mass of the total content of the (A) component and the (B) component.

[0085] [Component (D): Hindered Amine Light Stabilizer] A hindered amine light stabilizer is an additive that has the function of enhancing the light stability of a resin by capturing radicals, which are a factor in resin deterioration. The hindered amine light stabilizer has, for example, a hindered amine structure represented by the following formula (D-1):

[0086] In formula (D-1), X represents a substituent such as a hydrogen atom or a hydrocarbon group, and * represents a bond.

[0087] A wide variety of known hindered amine light stabilizers used in the field of resin materials can be used as component (D). From the viewpoint of achieving superior solubility in component (A) and superior weather resistance, a compound in which X in formula (D-1) is a methyl group (i.e., a compound having a structure represented by formula (D-2) below) may be used.

[0088] The molecular weight of component (D) may be, for example, 400 to 4000. From the viewpoint of achieving better solubility in component (A), the molecular weight of component (D) may be less than 1000, 700 or less, or 500 or less, or may be 400 or more and less than 1000, 400 to 700, or 400 to 500. Here, when component (D) contains multiple compounds, the molecular weight of component (D) means the weight-average molecular weight of the multiple compounds.

[0089] The base constant (pKb) of the component (D) may be, for example, 4 to 12, and may be 4 to 9 from the standpoint of superior solubility in the component (A).

[0090] Specific examples of the component (D) include a mixture of bis(1,2,2,6,6-pentamethyl-4-piperidinyl)sebacate and methyl(1,2,2,6,6-pentamethyl-4-piperidinyl)sebacate (Tinuvin 292, manufactured by BASF), a reaction product of 1,2,3,4-butanetetracarboxylic acid tetramethyl ester with 1,2,2,6,6-pentamethyl-4-piperidinol and β,β,β',β'-tetramethyl-2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-diethanol (ADEKA STAB®, manufactured by ADEKA Corporation), and a methyl bis(1,2,2,6,6-pentamethyl-4-piperidinyl)sebacate (Tinuvin 292, manufactured by BASF), a reaction product of 1,2,3,4-butanetetracarboxylic acid tetramethyl ester with 1,2,2,6,6-pentamethyl-4-piperidinol and β,β,β',β'-tetramethyl-2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-diethanol (ADEKA STAB®, manufactured by ADEKA Corporation). LA-63P), bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate (Tinuvin 770 manufactured by BASF), and 2,2,6,6-tetramethyl-1-[2-[(3,5,5-trimethyl-1-oxohexyl)oxy]ethyl]-4-piperidinyl 3,5,5-trimethylhexanoate (Tinuvin 249 manufactured by BASF).

[0091] From the viewpoint of achieving better weather resistance (particularly gloss retention), the content of the (D) component may be 0.05 parts by mass or more, 0.1 parts by mass or more, or 0.2 parts by mass or more, relative to 100 parts by mass of the total content of the (A) component and the (B) component. From the viewpoint of achieving better mechanical properties, the content of the (D) component may be 5 parts by mass or less, 3 parts by mass or less, or 1 part by mass or less, relative to 100 parts by mass of the total content of the (A) component and the (B) component. From the above viewpoint, the content of the (D) component may be 0.05 to 5 parts by mass, 0.1 to 3 parts by mass, or 0.2 to 3 parts by mass, relative to 100 parts by mass of the total content of the (A) component and the (B) component.

[0092] From the viewpoint of achieving better weather resistance, the total content of the (C) component and the (D) component may be 0.5 parts by mass or more, 0.6 parts by mass or more, or 0.7 parts by mass or more, per 100 parts by mass of the total content of the (A) component and the (B) component. From the viewpoint of achieving better mechanical properties, the total content of the (C) component and the (D) component may be 5 parts by mass or less, 3 parts by mass or less, or 1.5 parts by mass or less, per 100 parts by mass of the total content of the (A) component and the (B) component. From the above viewpoint, the total content of the (C) component and the (D) component may be 0.5 to 5 parts by mass, 0.6 to 3 parts by mass, or 0.7 to 1.5 parts by mass, per 100 parts by mass of the total content of the (A) component and the (B) component.

[0093] [Volatile Organic Compounds] Examples of volatile organic compounds include ketone compounds such as methyl ethyl ketone, acetylacetone, methyl isobutyl ketone, and cyclohexanone; aromatic compounds such as toluene and xylene; glycol ether compounds such as ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, and propylene glycol monomethyl ether acetate; ester compounds such as ethyl acetate, butyl acetate, methyl cellosolve acetate, and cellosolve acetate; Solvesso #100 and Solvesso #150 (all trade names, manufactured by ExxonMobil Corporation). The volatile organic compounds may also be components (A) to (D). In other words, even if a compound corresponds to components (A) to (D), an organic compound having a boiling point of 180°C or less at 1 atm is a volatile organic compound.

[0094] The content of the volatile organic compound is 0 to 5% by mass, based on the total mass of the composition. By having the content of the volatile organic compound in this range, good in-mold coatability can be obtained. The content of the volatile organic compound may be 1% by mass or less, or 0.1% by mass or less.

[0095] [Other Components] The composition may further contain other components in addition to the components described above. Examples of other components include catalysts for forming urethane resins. Examples of such catalysts include organotin compounds such as dioctyltin dilaurate, dibutyltin dilaurate, dibutyltin dioctoate, and tin 2-ethylhexanoate; iron compounds such as iron acetylacetonate and iron chloride; lithium compounds such as lithium acetylacetonate; lead compounds such as lead octoate; bismuth compounds such as bismuth octoate; zinc compounds such as zinc octoate; and tertiary amine catalysts such as triethylamine and triethylenediamine. The catalyst content may be, for example, 0.001 to 5.000% by mass based on the total mass of the composition.

[0096] The composition may further contain, as other components, for example, an antioxidant such as 2,6-di-tert-butyl-4-methylphenol, an ultraviolet absorber, a pigment, a dye, a flame retardant, a hydrolysis inhibitor, a lubricant, a plasticizer, a filler, an antistatic agent, a dispersant, a storage stabilizer, a thickener, an internal mold release agent, a surface conditioner, an antifoaming agent, an antibacterial agent, and the like.

[0097] The composition may further contain, as other components, a hydroxyl group-containing compound (a compound having a hydroxyl group) other than component (A) and an isocyanate group-containing compound (a compound having an isocyanate group) other than component (B). However, from the viewpoint of obtaining better transparency, the composition may not contain a hydroxyl group-containing compound having an aromatic ring and an isocyanate group-containing compound having an aromatic ring. The content of the hydroxyl group-containing compound having an aromatic ring may be 5% by mass or less, or may be 0% by mass, based on the total mass of the composition. The content of the isocyanate group-containing compound having an aromatic ring may be 5% by mass or less, or may be 0% by mass, based on the total mass of the composition.

[0098] The ratio of the number of moles of isocyanate groups in the isocyanate group-containing compound contained in the composition to the number of moles of hydroxyl groups in the hydroxyl group-containing compound contained in the composition (NCO / OH equivalent) may be 0.8 or more, 0.9 or more, or 1.0 or more, from the viewpoint of suppressing an excess of hydroxyl groups and further improving the durability and mechanical properties of the coating film. The NCO / OH equivalent may be 1.3 or less, 1.2 or less, or 1.1 or less, from the viewpoint of suppressing an excess of isocyanate groups and further improving the durability and mechanical properties of the coating film. From the above viewpoints, the NCO / OH equivalent may be 0.8 to 1.3, 0.9 to 1.2, or 1.0 to 1.1.

[0099] <In-mold coating agent set> Another embodiment of the present disclosure relates to a coating agent set for preparing the composition of the above embodiment. The coating agent set is, for example, a coating agent set for in-mold coating. The coating agent set includes a first agent containing the above-mentioned components (A), (C), and (D), and a second agent containing the above-mentioned component (B). When the coating agent set consists of the first agent and the second agent, the composition of the above embodiment can be prepared by mixing the first agent and the second agent.

[0100] The first agent of the coating agent set contains components (A), (C), and (D), and because the additives components (C) and (D) are easily soluble in component (A), the first agent can be prepared at relatively low temperatures (e.g., below 100°C). Furthermore, the first agent is unlikely to precipitate at typical storage temperatures (e.g., 0 to 50°C), demonstrating excellent low-temperature stability.

[0101] The first and second agents may contain the component (E) and may also contain other components that can be contained in the composition, but from the viewpoint of storage stability, a hydroxyl group-containing compound other than component (A) may be blended in the first agent, and an isocyanate group-containing compound other than component (B) may be blended in the second agent.

[0102] The coating agent set may further include other agents different from the first and second agents. The other agents may include other components that may be included in the composition, such as the component (E). When the coating agent set further includes other agents, the composition of the above embodiment can be prepared by mixing the first and second agents with the other agents.

[0103] The viscosity of the first agent at 25°C may be 1 to 15,000 mPa·s, or may be 5 to 1,000 mPa·s, or 10 to 5,000 mPa·s. When the viscosity of the first agent at 25°C is within the above range, a composition (coating agent) with even better film-forming properties is more likely to be obtained.

[0104] The viscosity of the second agent at 25°C may be 1 to 15,000 mPa·s, or may be 5 to 1,000 mPa·s, or 10 to 5,000 mPa·s. When the viscosity of the second agent at 25°C is within the above range, a composition (coating agent) with even better film-forming properties is more likely to be obtained.

[0105] In this specification, the viscosity at 25°C is a value measured using a Brookfield viscometer.

[0106] When using the in-mold coating agent set, for example, the first agent, the second agent, and any other agents that are used optionally may be mixed so that the NCO / OH equivalent falls within the above-mentioned range.

[0107] <Coating Film> Another embodiment of the present disclosure relates to a coating film containing a reaction product of the composition of the above embodiment. Here, the reaction product of the composition is a reaction product obtained by reacting the components (at least component (A) and component (B)) contained in the composition. Therefore, the coating film contains a polyurethane resin produced by the reaction of at least component (A) and component (B). The coating film may also contain some of the components contained in the composition (e.g., unreacted components).

[0108] The thickness of the coating is, for example, 1 to 10,000 μm, and may be 5 to 5,000 μm or 10 to 1,000 μm.

[0109] The coating film can be formed by forming a coating film made from the composition of the above embodiment and then reacting the composition. More specifically, it can be formed, for example, by the in-mold coating method described below. Since the reaction of the composition causes the coating film made from the composition to harden, the coating film made from the above composition and the coating film of the above embodiment can also be referred to as an uncured film and a cured film, respectively.

[0110] The coating film may be provided on a substrate such as a plastic molded product to form a part of a component (e.g., an interior component of an automobile) that includes the substrate. That is, in another embodiment, the present disclosure provides a component that includes a substrate and the coating film provided on the substrate.

[0111] <In-mold coating method> Another embodiment of the present disclosure relates to an in-mold coating method including: preparing a substrate and a mold with the substrate disposed therein; injecting the composition of the above embodiment into the mold, applying the composition to the surface of the substrate; and reacting the composition to form a coating film on the surface of the substrate. This method produces the coating film of the above embodiment. The in-mold coating method of this embodiment will be described below with reference to FIG.

[0112] 1 is a schematic diagram illustrating one embodiment of an in-mold coating method, in which a substrate 1 and a mold 2 having the substrate 1 disposed therein are first prepared (see FIG. 1( a)).

[0113] The substrate 1 is, for example, a molded body (plastic molded product) made of a plastic material. Examples of plastic materials include acrylic polyol resin, polycarbonate resin, polyethylene terephthalate resin, polyethylene naphthalate resin, polybutylene phthalate resin, polystyrene resin, AS resin, ABS resin, polycarbonate-ABS resin, 6-nylon resin, 6,6-nylon resin, MXD6 nylon resin, polyvinyl chloride resin, polyvinyl alcohol resin, polyurethane resin, phenolic resin, melamine resin, polyacetal resin, chlorinated polyolefin resin, polyolefin resin, polyamide resin, polyether ether ketone resin, polyphenylene sulfide resin, NBR resin, chloroprene resin, SBR resin, SEBS resin, and combinations thereof. The surface of the molded body may be subjected to a surface treatment such as corona discharge treatment. Another coating film that can serve as an intermediate layer may be formed on the surface of the molded body.

[0114] The mold 2 has a gap 2a for forming a coating film between the inner wall of the mold 2 and the substrate 1, an opening 2b for injecting the coating agent, and a flow path 2c for supplying the coating agent from the opening 2b to the gap 2a. The mold 2 may be the same mold as that used to mold the substrate 1, or may be a mold having an internal structure of the same shape as the target shape of the substrate 1. In this case, for example, after a plastic material heated and melted in an injection cylinder is injected into the mold 2 and cooled and pressurized to mold the substrate 1, the clamping force may be reduced or the gap between the obtained molded product (substrate) and the inner wall of the mold may be slightly opened, providing a gap 2a for forming a coating film between the substrate 1 and the mold 2.

[0115] Next, the first part 3 and the second part 4 are supplied to a tank 5 and mixed to prepare a composition 6 (a polyurethane resin-forming composition) of the above embodiment, and the composition 6 is poured into a mold 2 and applied to the surface 1a of the substrate 1 (see FIG. 1(b)). When preparing the composition 6, the first and second parts may be heated to mix the first part 3 and the second part 4 more uniformly. Furthermore, when pouring the composition 6, the composition 6 and the mold 2 may be heated to a degree that does not cause a significant increase in viscosity of the composition 6. However, the temperature of the composition 6 at the time of pouring may be 30°C or lower, and the temperature of the mold 2 at the time of pouring may be 85°C or lower.

[0116] Next, composition 6 is reacted to form a coating film 7 (e.g., a cured film) containing a reaction product of composition 6 on the surface of substrate 1 (see FIG. 1(c)). The reaction of composition 6 may be allowed to proceed by injecting composition 6 into a heated mold. The heating temperature may be any temperature that does not exceed the heat resistance of the substrate, and may be 50 to 150°C, or may be 50 to 85°C, from the viewpoint of coating film formability. In order to allow the reaction of composition 6 to proceed more fully, the coating film may be heated again after removing the substrate from the mold.

[0117] The present disclosure will be described in more detail below using examples and comparative examples, but the present disclosure is not limited to the following examples.

[0118] <Synthesis and Evaluation of Polycarbonate Polyol> (Synthesis Example 1) A reaction apparatus equipped with a stirrer, thermometer, heater, and distillation column was charged with 792 g of 3-methyl-1,5-pentanediol (manufactured by Kuraray Co., Ltd.) and 88 g of 1,6-hexanediol (manufactured by Tokyo Chemical Industry Co., Ltd.) as the polyol component (polyol mixture), 638 g of diethyl carbonate (manufactured by Tokyo Chemical Industry Co., Ltd.) as the carbonate component, and 0.05 g of tetrabutyl titanate as a reaction catalyst. The temperature inside the apparatus was gradually raised to 190°C under a nitrogen stream. When the distillation of ethanol slowed and the temperature at the top of the distillation column fell to 50°C or less, the pressure inside the apparatus was gradually reduced to 0.1 kPa while maintaining the temperature at 190°C, and the reaction was continued for another 5 hours at a pressure of 0.1 kPa to distill off the ethanol. This synthesized the polycarbonate polyol (PCP) of Synthesis Example 1.

[0119] (State Evaluation) The obtained polycarbonate polyol was heated to 100° C., then placed in a transparent glass bottle, and left to stand for 24 hours in an environment of 25° C. After standing, the glass bottle was tilted at 25° C., and the polycarbonate polyol was visually observed to determine whether it had fluidity. It was confirmed that the polycarbonate polyol had fluidity (i.e., was in a liquid state).

[0120] (Hydroxyl value measurement) The hydroxyl value of the polycarbonate polyol obtained in Synthesis Example 1 was evaluated by a method using an acetylation reagent in accordance with JIS K1557-1. Based on the hydroxyl value, the molecular weight of the polycarbonate polyol was calculated assuming the number of hydroxyl groups to be the theoretical value (calculated value) of 2. The hydroxyl value of the polycarbonate polyol was 226.8 mg KOH / g, and the molecular weight calculated from the hydroxyl value and the number of hydroxyl groups was 495.

[0121] Examples 1 to 13 and Comparative Examples 1 to 10 (Preparation of First Agent) Component (A) (polyol), component (C) (ultraviolet absorber), and component (D) (hindered amine light stabilizer) shown in Tables 1 to 3 were charged into a heating device equipped with a stirrer, thermometer, and heater in the amounts shown in Tables 1 to 3, and the temperature inside the device was gradually increased under a nitrogen stream. At this time, in Comparative Example 10, 10.00 parts by mass of butyl acetate was added as a solvent (volatile organic compound). After the solids had dissolved and become uniform, the mixture was cooled to room temperature to obtain a first agent.

[0122] (Calculation of average number of hydroxyl groups and average hydroxyl value) The average number of hydroxyl groups and average hydroxyl value of component (A) contained in the first agent were calculated using the following formulas. The results are shown in Tables 1 to 3. Average number of hydroxyl groups = (number of hydroxyl groups in (A) component 1 × amount of charged substance of (A) component 1 + number of hydroxyl groups in (A) component 2 × amount of charged substance of (A) component 2 + number of hydroxyl groups in (A) component 3 × amount of charged substance of (A) component 3) / total amount of charged substances of (A) components Average hydroxyl value = (hydroxyl value of (A) component 1 × charged mass of (A) component 1 + hydroxyl value of (A) component 2 × charged mass of (A) component 2 + hydroxyl value of (A) component 3 × charged mass of (A) component 3) / total mass of charged components of (A) components Here, (A) component 1, (A) component 2, and (A) component 3 refer to the respective materials blended as component (A). For example, in Example 1, (A) component 1 is "PCP" in the table, (A) component 2 is "1,3-BG" in the table, and (A) component 3 is "TMP" in the table.

[0123] (Solubility Evaluation) In preparing the first agent, the temperature at which the solid dissolved to give a homogeneous liquid (dissolution temperature) was measured, and the solubility of the additives (components (C) and (D)) was evaluated according to the following criteria: [Evaluation Criteria] A: Dissolution temperature less than 80°C B: Dissolution temperature 80°C or higher but lower than 90°C C: Dissolution temperature 90°C or higher but lower than 100°C D: Dissolution temperature 100°C or higher, or a homogeneous liquid was not obtained.

[0124] (Low temperature stability evaluation) The first agent was stored in a constant temperature environment (0°C, 25°C, or 50°C) for 1 hour, and the occurrence of precipitates was confirmed, and the low temperature stability was evaluated according to the following criteria. If the result of this evaluation was D, the subsequent evaluations were not carried out. [Evaluation criteria] A: No precipitates were generated at 0°C. B: Precipitates were generated at 0°C and no precipitates were generated at 25°C. C: Precipitates were generated at 25°C and no precipitates were generated at 50°C. D: Precipitates were generated at 50°C.

[0125] (Preparation of composition and production of coating film) Dioctyltin dilaurate (referred to as "DOTDL" in the table) was added to the first agent, and Coronate HXLV (referred to as "C-HXLV" in the table) was prepared as the second agent. The first and second agents prepared above were thoroughly mixed at room temperature to obtain a uniform composition. The ratio of OH groups in component (A) (polyol) to NCO groups in component (B) (polyisocyanate) was NCO / OH = 1.05.

[0126] Next, a coating liquid composed of the obtained composition was applied to a white steel plate substrate. Two guides, each 600 μm high, were provided on the substrate, and the coating liquid was poured between the two guides to adjust the cured film thickness to 600 μm. To simulate the conditions for in-mold coating, a release-treated glass was placed on the guides to cover the coating film (uncured film composed of the coating liquid), and the coating film was then cured at 80°C for 1 hour. This was followed by aging at 60°C for 12 hours to form a coating film (cured film) containing a reaction product of the composition. The laminate composed of the substrate and coating film (cured film) thus obtained was used as a test piece and the following evaluations were performed.

[0127] (Evaluation of Coating Film Formability) The appearance of the coating film of the test piece obtained above was visually observed, and the coating film formability was evaluated according to the following criteria. If the result of this evaluation was B, the following evaluations were not carried out. [Evaluation criteria] A: No abnormal appearance such as bubbles was found inside the coating film. B: An abnormal appearance such as bubbles was found inside the coating film.

[0128] (Weathering Test) The test specimens obtained above were subjected to a weathering test for 1,584 hours using a QUV accelerated weathering tester (manufactured by Q-Lab Corporation) under the following conditions: [Conditions] Standard: ASTM G154 Cycle No.: 5 (lamp: UVB-313, light irradiation: 0.62 W / m ２ , 80°C; condensation: 50°C, light irradiation / condensation cycle = 20 hours / 4 hours)

[0129] (Measurement of b* and evaluation of yellowing resistance) Using a Spectro 2 Guide (manufactured by BYK-Chemie Co., Ltd.), the b* of the test piece obtained above was measured before and after the weathering test. In addition, the b* of the test piece after the weathering test was used to evaluate the yellowing resistance according to the following criteria. The results are shown in Tables 1 to 3. [Evaluation criteria] A: b* is less than 3.0 B: b* is 3.0 or more and less than 4.0 C: b* is 4.0 or more and less than 5.0 D: b* is 5.0 or more

[0130] (Evaluation of Gloss Retention) Using Micro Trigloss (manufactured by BYK-Chemie Co., Ltd.), the gloss at 20° and 60° of the test piece obtained above was measured before and after the weathering test, and the gloss retention was calculated. Gloss retention (%) = 100 × [(gloss of test piece after weathering test) / (gloss of test piece before weathering test)]

[0131] Using the calculated gloss retention, the gloss retention was evaluated according to the following criteria: [Evaluation criteria for 20° gloss retention] A: Gloss retention of 90% or more B: Gloss retention of 85% or more but less than 90% C: Gloss retention of 80% or more but less than 85% D: Gloss retention of less than 80% [Evaluation criteria for 60° gloss retention] A: Gloss retention of 95% or more B: Gloss retention of 90% or more but less than 95% C: Gloss retention of 85% or more but less than 90% D: Gloss retention of less than 85%

[0132] (Evaluation of surface roughness) Using a scanning white light interference microscope VS-1530 (manufactured by Hitachi High-Tech Corporation), the arithmetic mean height Sa of the test piece after the weather resistance test was measured, and the surface roughness was evaluated according to the following criteria. The magnification of the objective lens was 2.5 times, and the analysis conditions were surface correction (primary). [Evaluation criteria] Test piece after weather resistance test: A: Sa is less than 0.2 μm; B: Sa is 0.2 μm or more and less than 0.4 μm; C: Sa is 0.4 μm or more and less than 0.6 μm; D: Sa is 0.6 μm or more, or the coating surface is so uneven that it cannot be measured.

[0133] (Evaluation of Self-Repairing Property) The self-repairing property of the test piece obtained above was evaluated before and after the weather resistance test by the following method. First, a brass brush was applied perpendicularly to the coating film, and scratches were made five times with a load of 2 kg. After the scratching, the test piece was left to stand in an environment of 50°C for 5 minutes, and then the presence or absence of scratches was visually confirmed, and the self-repairing property was evaluated according to the following criteria. [Evaluation criteria] A: No scratches B: Scratches

[0134]

[0135]

[0136]

[0137] Details of the materials shown in Tables 1 to 3 are as follows: 1,3-BG: 1,3-butanediol (manufactured by Tokyo Chemical Industry Co., Ltd., number of hydroxyl groups: 2, hydroxyl value: 1245 mg KOH / g) TMP: trimethylolpropane (manufactured by Tokyo Chemical Industry Co., Ltd., number of hydroxyl groups: 3, hydroxyl value: 1254 mg KOH / g) GP250: Sannix GP-250 (manufactured by Sanyo Chemical Industries, Ltd., polyether polyol, number of hydroxyl groups: 3, hydroxyl value: 670 mg KOH / g) GK400: Sannix GK-400 (manufactured by Sanyo Chemical Industries, Ltd., polyether polyol, number of hydroxyl groups: 2, hydroxyl value: 400 mg KOH / g) Triazine (1): Tinuvin 405 (manufactured by BASF, 2-[4-[(2-hydroxy-3-(2'-ethyl)hexyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine) Triazine (2): 2-(4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl)-5-(octyloxy)phenol) (manufactured by BLD Pharmatech) Oxalic acid anilide: HOSTAVIN VSU (manufactured by Clariant Chemicals K.K.) Benzophenone: 2-hydroxy-4-(octyloxy)benzophenone (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) Salicylate: 4-tert-butylphenyl salicylate (manufactured by Tokyo Chemical Industry Co., Ltd.) Cyanoacrylate: 2-cyano-3,3-diphenyl ethyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) HALS (1): Tinuvin 292 (manufactured by BASF, molecular weight 509, 370 (mixture), N-CH ３ HALS (2): Adekastab LA-63P (manufactured by ADEKA Corporation, molecular weight 2000, N-CH ３ type HALS) DOTDL: dioctyltin dilaurate (manufactured by Kishida Chemical Co., Ltd.) C-HXLV: isocyanurate-modified hexamethylene diisocyanate (manufactured by Tosoh Corporation), trade name: Coronate HXLV (NCO content 23.4% by mass)

[0138] 1... substrate, 2... mold, 3... first agent, 4... second agent, 6... polyurethane resin-forming composition, 7... coating film

Claims

1. A polyurethane resin-forming composition comprising: (A) a polyol; (B) a polyisocyanate; (C) an ultraviolet absorber; and (D) a hindered amine-based light stabilizer, wherein the (A) component comprises a polycarbonate polyol; the (C) component comprises at least one of a triazine-based ultraviolet absorber and an oxalic acid anilide-based ultraviolet absorber; and the content of volatile organic compounds is 0 to 5 mass %.

2. The polyurethane resin-forming composition according to claim 1, wherein the average hydroxyl value of component (A) is 300 to 800 mgKOH / g.

3. The polyurethane resin-forming composition according to claim 1, wherein the content of the polycarbonate polyol is 30 mass% or more based on the total mass of the component (A).

4. The polyurethane resin-forming composition according to claim 1, wherein the component (C) contains a triazine-based ultraviolet absorber.

5. The polyurethane resin-forming composition according to claim 4, wherein the triazine-based ultraviolet absorber comprises a compound represented by the following formula (C-2): [In formula (C-2), R １１ represents an alkyl group having 1 to 15 carbon atoms; R ２ ~R ５ each independently represents a hydrogen atom, a hydroxyl group, a methyl group, or an ethyl group.

6. The polyurethane resin-forming composition according to claim 1, wherein the molecular weight of component (D) is less than 1,000.

7. The polyurethane resin-forming composition according to claim 1, wherein the component (D) includes a compound having a structure represented by the following formula (D-2): [In formula (D-2), * represents a bond.] 8. A polyurethane resin-forming composition as described in claim 1, wherein the content of the (D) component is 0.05 parts by mass or more per 100 parts by mass of the total content of the (A) component and the (B) component.

9. A polyurethane resin-forming composition as described in claim 1, wherein the total content of the (C) component and the (D) component is 0.5 parts by mass or more per 100 parts by mass of the total content of the (A) component and the (B) component.

10. The polyurethane resin-forming composition according to claim 1, which is used as a coating agent for coating inside a mold.

11. A coating agent set for preparing the polyurethane resin-forming composition according to any one of claims 1 to 10, comprising a first agent containing the components (A), (C), and (D), and a second agent containing the component (B).

12. A coating comprising the reaction product of the composition of any one of claims 1 to 10.

13. A method for forming a coating film, comprising: preparing a substrate and a mold having the substrate disposed therein; injecting a composition according to any one of claims 1 to 10 into the mold and applying the composition to a surface of the substrate; and reacting the composition to form a coating film on the surface of the substrate.

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