Polyol composition, polyurethane resin-forming composition, coating agent set, coating film, and method for forming a coating film.

Abstract

The objective is to ensure sufficient reactivity of a polyol composition containing at least one of a polycarbonate polyol and a polyester polyol and a urethane-based metal catalyst toward polyisocyanate, while suppressing changes in viscosity of the composition over time. [Solution] A polyol composition comprising (A) a polyol selected from the group consisting of polycarbonate polyols and polyester polyols, (B) a urethane metal catalyst, (C) at least one carbonyl compound selected from the group consisting of carboxylic acids, carboxylic acid anhydrides and β-diketones, and (D) a hindered amine-based light stabilizer, wherein the content of volatile organic compounds is 0 to 10% by mass.

Description

[Technical Field]

[0001] This disclosure relates to a polyol composition, a polyurethane resin-forming composition, a coating agent set, a coating film, and a method for forming a coating film. [Background technology]

[0002] Polyurethane resin-forming compositions containing polyols and polyisocyanates are used as coating agents. Polyurethane resin-forming compositions are generally two-component compositions, prepared by storing a composition containing a polyol as the main component (polyol composition) and a polyisocyanate separately and mixing them at the time of application. Examples of polyols used in coating agents include polycarbonate polyols, polyester polyols, and polyether polyols.

[0003] In recent years, in-mold coating has attracted attention as a method for coating the surface of plastic molded products, etc., from the perspective of reducing environmental impact (see, for example, Patent Document 1). In-mold coating is a method in which a coating agent is injected into a mold, such as a die, while the substrate is placed inside the mold, and the coating agent is reacted to form a coating film on the surface of the substrate. With this method, the mold used to form the substrate can be used as the mold for coating, so it is possible to coat the surface of the substrate in fewer steps compared to conventional coating methods, and it is possible to reduce the amount of waste and energy consumption associated with coating. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2005-074896 [Overview of the project] [Problems that the invention aims to solve]

[0005] Polyol compositions contain a metal catalyst (urethane-forming metal catalyst) as a catalyst for urethane formation to ensure sufficient reactivity with polyisocyanates. However, when a polyol composition contains at least one of polycarbonate polyols and polyester polyols and a urethane-forming metal catalyst, the viscosity of the polyol composition may change significantly due to storage over a certain period. Such viscosity changes affect the miscibility between the polyol composition and polyisocyanates and can lead to a decrease in workability during painting.

[0006] Therefore, one aspect of this disclosure aims to ensure sufficient reactivity of a polyol composition containing at least one of a polycarbonate polyol and a polyester polyol and a urethane-based metal catalyst with respect to a polyisocyanate, while suppressing changes in the viscosity of the composition over time. [Means for solving the problem]

[0007] Some aspects of this disclosure provide the following [1] to [9].

[0008] [1] (A) A polyol comprising at least one selected from the group consisting of polycarbonate polyols and polyester polyols, (B) Urethane metal catalyst, (C) At least one carbonyl compound selected from the group consisting of carboxylic acids, carboxylic acid anhydrides, and β-diketones, (D) Contains a hindered amine-based light stabilizer, A polyol composition having a volatile organic compound content of 0 to 10% by mass.

[0009] [2] (E) The polyol composition according to [1], further containing an ultraviolet absorber.

[0010] [3] The polyol composition according to [1] or [2], wherein the component (C) contains at least one selected from the group consisting of carboxylic acids and β-diketones.

[0011] [4] The polyol composition according to any one of [1] to [3], wherein the content of the component (C) is 0.1 to 30.0 mol with respect to 1 mol of the component (B).

[0012] [5] (A) A polyol containing at least one selected from the group consisting of a polycarbonate polyol and a polyester polyol, (B) A urethanization metal catalyst, (C) At least one carbonyl compound selected from the group consisting of carboxylic acids, carboxylic anhydrides, and β-diketones, (D) A hindered amine light stabilizer, (F) A polyisocyanate, and containing, A polyurethane resin-forming composition having a volatile organic compound content of 0 to 10% by mass.

[0013] [6] The polyurethane resin-forming composition according to [5], which is used as a coating agent for in-mold coating

[0014] [7] A coating agent set for preparing the polyurethane resin-forming composition according to [5] or [6], Comprising a first agent containing the component (A), the component (B), the component (C), and the component (D), and a second agent containing the component (F).

[0015] [8] A coating film containing a reaction product of the polyurethane resin-forming composition according to [5] or [6].

[0016] [9] Preparing a substrate and a mold in which the substrate is disposed inside, The polyurethane resin-forming composition described in [5] or [6] is injected into the mold, and the polyurethane resin-forming composition is applied to the surface of the substrate, A method for forming a coating film, comprising reacting the polyurethane resin-forming composition to form a coating film on the surface of the substrate. [Effects of the Invention]

[0017] According to one aspect of this disclosure, it is possible to suppress changes in viscosity of a polyol composition over time while ensuring sufficient reactivity of the polyol composition containing at least one of a polycarbonate polyol and a polyester polyol and a urethane metal catalyst with respect to a polyisocyanate. [Brief explanation of the drawing]

[0018] [Figure 1] This is a schematic diagram illustrating one embodiment of the in-mold coating method of the present disclosure. [Modes for carrying out the invention]

[0019] Several embodiments of this disclosure are described below. However, this disclosure is not limited to the embodiments described below.

[0020] In this specification, numerical ranges indicated using "~" represent a range that includes the numbers before and after "~" as the minimum and maximum values, respectively. Unless otherwise specified, the units of the numbers before and after "~" are the same. In numerical ranges described in stages within this specification, the upper or lower limit of one stage may be replaced with the upper or lower limit of another stage. Furthermore, in numerical ranges described within this specification, the upper or lower limit of that range may be replaced with the values ​​shown in the examples. Also, individually stated upper and lower limits can be combined in any way. The materials exemplified below may be used individually or in combination of two or more, unless otherwise specified. The content of each component in a composition, if multiple substances corresponding to each component exist in the composition, means the total amount of those multiple substances present in the composition, unless otherwise specified.

[0021] <Polyol composition> One embodiment of the present disclosure relates to a polyol composition containing (A) a polyol comprising at least one selected from the group consisting of polycarbonate polyols and polyester polyols (hereinafter also referred to as "component (A)"), (B) a urethane metal catalyst (hereinafter also referred to as "component (B)"), (C) at least one carbonyl compound selected from the group consisting of carboxylic acids, carboxylic acid anhydrides, and β-diketones (hereinafter also referred to as "component (C)"), and (D) a hindered amine light stabilizer (hereinafter also referred to as "component (D)"), wherein the content of volatile organic compounds (based on the total mass of the polyol composition) is 0 to 10% by mass. Here, "volatile organic compound" means an organic compound having a boiling point of 180°C or less at 1 atm.

[0022] The above polyol composition exhibits sufficient reactivity with polyisocyanates while being less susceptible to viscosity changes over time. The reason for this effect is unclear, but it is presumed to be as follows.

[0023] Polycarbonate polyols and polyester polyols contain multiple types of polyols with different molecular weights due to their manufacturing process. However, when a urethane metal catalyst is present in the composition, it is presumed that the urethane metal catalyst promotes the transesterification reaction between these polyols, causing a change in the molecular weight distribution of the polyols over time and resulting in a change in the viscosity of the polyol composition. On the other hand, in the above polyol composition, it is presumed that the specific carbonyl compound added as component (C) coordinates with the urethane metal catalyst, thereby suppressing the catalytic activity of the urethane metal catalyst in the transesterification reaction with the polyols. This suppresses the transesterification reaction between the polyols and thus suppresses the change in viscosity over time.

[0024] Since the above polyol composition has sufficient reactivity with polyisocyanate, a composition containing the above polyol composition and polyisocyanate has polyurethane resin-forming properties. In this specification, a composition containing the above polyol composition and polyisocyanate is referred to as a polyurethane resin-forming composition.

[0025] The above polyol composition tends to maintain its reactivity with polyisocyanate even after storage for a certain period. The reason for this is not clear, but it is presumed that the specific carbonyl compound added as component (C) protects the urethane metal catalyst by coordinating with it, thereby suppressing catalyst deactivation.

[0026] The above polyol composition tends to improve the weather resistance (particularly gloss retention) of a coating film made of polyurethane resin formed using the above polyol composition and polyisocyanate. Specifically, coating films formed using the above polyol composition and polyisocyanate tend to show less deterioration of surface gloss due to the influence of the usage environment such as light, temperature, and humidity. Therefore, the above polyol composition is suitable for forming coating films, and is particularly suitable for forming coating films that can maintain good surface gloss even when used on parts that require weather resistance (for example, plastic molded products used in interior and exterior parts of automobiles).

[0027] The above polyol composition is suitable for in-mold coating because the content of volatile organic compounds (based on the total mass of the polyol composition) is 0 to 10% by mass. In general coating agents, volatile organic compounds are used as solvents to dissolve additives. However, in in-mold coating, the use of solvents (volatile organic compounds) is restricted to avoid defects in coating film formation due to air bubbles, etc., because the inside of the mold is a sealed space. Therefore, when additives are used in coating agents for in-mold coating, energy such as thermal energy is required to dissolve the additives, which increases the energy consumption during preparation. On the other hand, in the above polyol composition, components (B), (C), and (D), which are additives, are readily soluble in component (A). Therefore, the above polyol composition tends to reduce energy consumption during preparation.

[0028] The following describes the components that may be included in the polyol composition.

[0029] [(A) component] Component (A) comprises at least one selected from the group consisting of polycarbonate polyols and polyester polyols. Component (A) may be a single polyol or a combination of two or more polyols.

[0030] Component (A) may be liquid at 25°C for superior film-forming properties in in-mold coating. In this specification, "liquid at 25°C" means that when heated to 80°C or higher, then left to stand at 25°C for 24 hours, and then tilted, at least slight fluidity can be observed visually.

[0031] Polycarbonate polyols are compounds having multiple hydroxyl groups (-OH) and multiple carbonate groups (-OCOO-). For example, polycarbonate polyols are reaction products of a polyol component (hereinafter also referred to as "component (a1)") and a carbonate component (hereinafter also referred to as "component (a2)"), and contain component (a1) and component (a2) as monomer units.

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

[0033] (a1) Component may contain glycol. Glycols are compounds having a structure in which two carbon atoms of a chain aliphatic hydrocarbon or a cyclic aliphatic hydrocarbon are each substituted with one hydroxyl group. 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, 1,16-he Examples include linear glycols such as xadecanediol, 1,18-octadecanediol, and 1,20-eicosanediol, 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, and 1,12-octadecanediol. (a1) When component contains some of these glycols individually or in specific combinations of several glycols, the polycarbonate polyol is liquid at 25°C.

[0034] Polycarbonate polyols tend to become liquid at 25°C the lower the crystallinity of component (a1). Furthermore, polycarbonate polyols tend to become liquid at 25°C when two or more components (a1) are used in combination. Also, when two or more components (a1) 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. Additionally, when two or more components (a1) are used in combination, the polycarbonate polyol is even more likely to become liquid at 25°C if it includes a component (a1) with a short carbon chain (for example, a component (a1) with 6 or fewer carbon atoms) and / or a branched component (a1).

[0035] For example, if 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., if the polycarbonate polyol 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 as monomer units), the polycarbonate polyol tends to become liquid at 25°C.

[0036] (a1) Component may contain a polyol having three or more hydroxyl groups. The content of the polyol having three or more hydroxyl groups in component (a1) may be 0 to 45% by mass, 0 to 20% by mass, or 0 to 5% by mass, based on the total mass of component (a1).

[0037] Component (a2) can be any compound capable of condensing with component (a1) to produce a polycarbonate polyol. Examples of 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, diantlyl carbonate, diphenanthryl carbonate, diindanyl carbonate, and bistetrahydronaphthyl carbonate. These may be used individually or in combination of two or more.

[0038] The polycarbonate polyol may be a reaction product obtained by reacting the reaction product of component (a1) and component (a2), or component (a1) and component (a2), with another reactant (e.g., polyester polyol) in the presence of a catalyst. When the other reactant is polyester polyol, the polycarbonate polyol can be called polyester polycarbonate polyol. The polyester polycarbonate polyol contains the above components (a1) and (a2) as monomer units and also contains an ester skeleton derived from polyester polyol.

[0039] The hydroxyl value of the polycarbonate polyol may be, for example, 100 to 400 mg KOH / g. Having a hydroxyl value within this range enhances the low-temperature processability of the polyurethane resin-forming composition, and tends to result in a better appearance of the coating film formed in the in-mold coating method. From the viewpoint of further enhancing the low-temperature processability of the polyurethane resin-forming composition, improving the compatibility between the polyol composition and polyisocyanate, and further improving coating film formation, the hydroxyl value of the polycarbonate polyol may be 150 mg KOH / g or higher, or 200 mg KOH / g or higher. From the viewpoint of forming a coating film with superior mechanical properties, the hydroxyl value of the polycarbonate polyol may be 380 mg KOH / g or lower, or 350 mg KOH / g or lower. From these viewpoints, the hydroxyl value of the polycarbonate polyol may be 150 to 380 mg KOH / g or 200 to 350 mg KOH / g.

[0040] In this specification, hydroxyl value refers to the number of milligrams (mg) of potassium hydroxide equivalent to hydroxyl groups in 1 g of sample, and is measured in accordance with JIS K1557-1.

[0041] The molecular weight of the polycarbonate polyol may be, for example, 200 or more. From the viewpoint of obtaining a coating film with superior 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 polyurethane resin-forming composition, improving the compatibility between the polyol composition and polyisocyanate, and further improving coating film formation, 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.

[0042] In this specification, molecular weight is defined as the molecular weight measured by gel permeation chromatography (for example, the converted molecular weight using a polycarbonate diol consisting of 1,6-hexanediol as a calibration curve), but it can also be calculated from the hydroxyl value and the number of hydroxyl groups (theoretical value).

[0043] The above polycarbonate polyol can be obtained, for example, by reacting component (a1) and component (a2) under a catalyst such as tetrabutoxytitanium. The reaction may be carried out, for example, under a nitrogen atmosphere in a reaction apparatus equipped with a stirrer, thermometer, heating device and distillation column. Specifically, for example, under a nitrogen atmosphere, the temperature can be gradually increased to 190°C while distilling off ethanol, and then the pressure can be gradually reduced to 0.5 kPa or less, and the reaction can be carried out at a pressure of 0.5 kPa or less for 4 hours or more to obtain a polycarbonate polyol as a reaction product of component (a1) and component (a2). The mixing ratio of each component may be adjusted as appropriate, for example, from the viewpoint of hydroxyl value.

[0044] From the viewpoint of obtaining better weather resistance, the content of polycarbonate polyol in component (A) may be 30% by mass or more, 50% by mass or more, or 60% by mass or more, based on the total mass of component (A). From the viewpoint of obtaining better weather resistance, the content of polycarbonate polyol in 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 component (A). From the above viewpoint, the content of polycarbonate polyol in component (A) may be 30 to 90% by mass, 50 to 85% by mass or 60 to 80% by mass, based on the total mass of component (A).

[0045] Polyester polyols are compounds having multiple hydroxyl groups (-OH) and multiple ester bonds (-COO-). Examples of polyester polyols include condensed polyester polyols and lactone-based polyester polyols. Condensed polyester polyols are, for example, condensed polymers of a polyol component (hereinafter also referred to as "component (a3)") and a dicarboxylic acid component (hereinafter also referred to as "component (a4)"), and contain component (a3) ​​and component (a4) as monomer units. Lactone-based polyester polyols are, for example, ring-opening addition polymers of cyclic ester compounds such as lactones (hereinafter also referred to as "component (a5)"), and contain component (a5) as a monomer unit.

[0046] (a3) Examples of component (a3) ​​include the same glycols listed in component (a1) above.

[0047] (a4) Examples of components include polybasic acids such as oxalic acid, malonic acid, maleic acid, adipic acid, tartaric acid, pimelic acid, sebacic acid, phthalic acid, and terephthalic acid, or their anhydrides or ester-forming derivatives. These may be used individually or in combination of two or more.

[0048] (a5) Examples of components include β-propiolactone, β-butyrolactone, γ-butyrolactone, β-valerolactone, γ-valerolactone, δ-valerolactone, α-caprolactone, β-caprolactone, γ-caprolactone, δ-caprolactone, ε-caprolactone, α-methyl-ε-caprolactone, β-methyl-ε-caprolactone, 4-methylcaprolactone, γ-caprylolactone, ε-caprylolactone, and ε-palmitractone. These may be used individually or in combination of two or more.

[0049] The hydroxyl value of the polyester polyol may be, for example, 100 to 400 mg KOH / g. Having the hydroxyl value of the polyester polyol within this range improves the low-temperature processability of the polyurethane resin-forming composition, and tends to result in a better appearance of the coating film formed in the in-mold coating method. From the viewpoint of further improving the low-temperature processability of the polyurethane resin-forming composition, enhancing the compatibility between the polyol composition and polyisocyanate, and further improving coating film formation, the hydroxyl value of the polyester polyol may be 150 mg KOH / g or more, or 200 mg KOH / g or more. From the viewpoint of forming a coating film with superior mechanical properties, the hydroxyl value of the polyester polyol may be 380 mg KOH / g or less, or 350 mg KOH / g or less. From these viewpoints, the hydroxyl value of the polyester polyol may be 150 to 380 mg KOH / g or 200 to 350 mg KOH / g.

[0050] The molecular weight of the polyester polyol may be, for example, 200 or more. From the viewpoint of obtaining a coating film with superior mechanical properties, the molecular weight of the polyester 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 polyurethane resin-forming composition, improving the compatibility between the polyol composition and the polyisocyanate, and further improving the coating film formation properties, the molecular weight of the polyester polyol may be 1100 or less, 1000 or less, or 800 or less. From these viewpoints, the molecular weight of the polyester polyol may be 200 to 1100, 300 to 1000, or 400 to 800.

[0051] From the viewpoint of obtaining better weather resistance, the polyester polyol content in component (A) may be 30% by mass or more, 50% by mass or more, or 60% by mass or more, based on the total mass of component (A). From the viewpoint of obtaining better weather resistance, the polyester polyol content in 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 component (A). From the above viewpoint, the polyester polyol content in component (A) may be 30 to 90% by mass, 50 to 85% by mass or 60 to 80% by mass, based on the total mass of component (A).

[0052] Component (A) may consist only of a polyol selected from the group consisting of polycarbonate polyols and polyester polyols (hereinafter referred to as "polyol (A1)"), but may also contain other polyols (hereinafter referred to as "polyol (A2)").

[0053] From the viewpoint of obtaining better weather resistance, the content of polyol (A1) in component (A) may be 30% by mass or more, 50% by mass or more, or 60% by mass or more, based on the total mass of component (A). From the viewpoint of obtaining better weather resistance, the content of polyol (A1) in 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 component (A). From the above viewpoint, the content of polyol (A1) in component (A) may be 30 to 90% by mass, 50 to 85% by mass or 60 to 80% by mass, based on the total mass of component (A).

[0054] As polyol (A2), a polyol with a molecular weight of less than 200 (hereinafter referred to as "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, and may be 60 to 180 or 70 to 150.

[0055] 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, it is easier to obtain a coating film with superior self-healing properties, and it also improves the compatibility between the polyol composition and the polyisocyanate, as well as enhances coating film formation due to lower viscosity.

[0056] 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, and dimer diol. To obtain a coating film with superior self-healing properties, and to improve the compatibility between the polyol composition and the polyisocyanate, as well as to enhance coating film formation by lowering viscosity, at least one selected from the group consisting of 1,3-butanediol and 2-methyl-1,3-propanediol may be used. The above diols can be used alone or in combination of two or more.

[0057] The content of the above-mentioned diol may be 5 to 55% by mass, 10 to 50% by mass, or 15 to 40% by mass, based on the total mass of component (A), from the viewpoint of obtaining a coating film with better self-healing properties, improving compatibility between the polyol composition and polyisocyanate, and further enhancing coating film formation by lowering viscosity.

[0058] The content of low molecular weight polyols may be 10 to 70% by mass, 15 to 50% by mass, or 20 to 40% by mass, based on the total mass of component (A), from the viewpoint of suppressing a decrease in self-healing properties and curability.

[0059] The average hydroxyl value of component (A) may be 300 mg KOH / g or more, or 400 mg KOH / g or more, or 500 mg KOH / g or more, from the viewpoint of having superior weather resistance (especially gloss retention). The average hydroxyl value of component (A) may be 800 mg KOH / g or less, or 700 mg KOH / g or less, or 600 mg KOH / g or less, from the viewpoint of further improving the low-temperature processability of the polyurethane resin-forming composition, improving the compatibility between the polyol composition and the polyisocyanate, and further improving the coating film formation. From these viewpoints, the average hydroxyl value of component (A) may be 300 to 800 mg KOH / g, or 400 to 700 mg KOH / g or 500 to 600 mg KOH / g. The average hydroxyl value of component (A) is the weighted average of the hydroxyl values ​​weighted by the mass of each polyol contained in component (A). It is calculated by multiplying the hydroxyl value of each polyol by its respective mass, summing the values, and dividing by the mass of component (A) (the total mass of each polyol).

[0060] The average number of hydroxyl groups in component (A) may be 2.0 to 3.0, or 2.0 to 2.5 or 2.0 to 2.3, from the viewpoint of obtaining better weather resistance. The average number of hydroxyl groups in component (A) is the weighted average value of the number of hydroxyl groups weighted by the amount of substance of each polyol contained in component (A), and is obtained by multiplying the number of hydroxyl groups of each polyol by their respective amounts of substance, finding the sum, and dividing by the amount of substance of component (A) (the sum of the amounts of substance of each polyol).

[0061] (A) The content of component may be, for example, 50-99% by mass, 60-98% by mass, or 70-97% by mass, based on the total mass of the polyol composition.

[0062] [(B) Component] Component (B) (urethane metal catalyst) is a metal catalyst that promotes urethane formation through the reaction of polyol and polyisocyanate. Examples of component (B) include tin compounds, iron compounds, lithium compounds, lead compounds, zinc compounds, etc. These may be used individually or in combination of two or more. Component (B) may contain a tin compound from the viewpoint of promoting the reaction between polyol and polyisocyanate and obtaining a good coating appearance.

[0063] Examples of tin compounds include dioctyl tin dilaurate, dibutyl tin dilaurate, dibutyl tin dioctoate, tin 2-ethylhexanoate, dibutyl tin oxylaurate, dibutyl tin diacetate, dibutyl tin bis(acetylacetonate), and dibutyl tin diversate. These can be used individually or in combination of two or more. Dibutyl tin dilaurate may be used as the tin compound from the viewpoint of promoting the reaction between the polyol and the polyisocyanate, and from the viewpoint of obtaining a good coating film appearance.

[0064] Examples of iron compounds include iron acetylacetonate and iron chloride. These can be used individually or in combination of two or more.

[0065] Examples of lithium compounds include lithium acetylacetonate and lithium octylate. These can be used individually or in combination of two or more.

[0066] Examples of lead compounds include lead octoate. These can be used individually or in combination of two or more.

[0067] Examples of zinc compounds include zinc octoate. These can be used individually or in combination of two or more.

[0068] From the viewpoint of promoting the reaction between the polyol and the polyisocyanate, the content of component (B) may be 0.1 parts by mass or more, 0.3 parts by mass or more, or 0.5 parts by mass or more per 100 parts by mass of component (A). From the viewpoint of reducing the rate of change in viscosity over time and obtaining better weather resistance and hydrolysis resistance, the content may be 3.5 parts by mass or less, 1.5 parts by mass or less, or 1.0 part by mass or less per 100 parts by mass of component (A). From these viewpoints, the content of component (B) may be 0.1 to 3.5 parts by mass, 0.3 to 1.5 parts by mass, or 0.5 to 1.0 parts by mass per 100 parts by mass of component (A).

[0069] [(C) component] Component (C) comprises at least one carbonyl compound selected from the group consisting of carboxylic acids, carboxylic acid anhydrides, and β-diketones. These carbonyl compounds may have coordinating properties with component (B). For example, component (C) may be a carbonyl compound that can form a coordination bond with the metal constituting component (B). Component (C) may be a single carbonyl compound or a combination of two or more carbonyl compounds.

[0070] A carboxylic acid has at least one carboxyl group (-COOH). The number of carboxyl groups in a carboxylic acid may be one or more. From the viewpoint of excellent solubility in polyols and promoting the reaction between polyols and isocyanates, the number may be 1 to 3, and from the viewpoint of further promoting the reaction between polyols and isocyanates, it may be 1. From the viewpoint of reducing the rate of change in viscosity over time, the carboxylic acid may be a compound represented by the following formula (C-1). [ka]

[0071] In formula (C-1), R 1cThis represents an alkyl group having 1 to 17 carbon atoms. The alkyl group may be linear or branched. The number of carbon atoms in the alkyl group may be 3 to 15 or 5 to 11. Examples of alkyl groups include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, 1-ethylpentyl group, 1-butylheptyl group, and the like.

[0072] Specific examples of carboxylic acids include acetic acid, propanoic acid, butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, dodecanoic acid, tetradecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, 2-ethylhexanoic acid, 2-butyloctanoic acid, isobutanoic acid, isopentanoic acid, and citric acid. These can be used individually or in combination of two or more. From the viewpoint of excellent solubility in polyols, carboxylic acids with 2 to 12 carbon atoms and branched carboxylic acids such as 2-ethylhexanoic acid may be used, and among these, it is preferable to use a carboxylic acid that is liquid at 40°C. From the viewpoint of further reducing the rate of change in viscosity over time, at least one selected from the group consisting of 2-ethylhexanoic acid, isobutanoic acid, isopentanoic acid, and 2-butyloctanoic acid may be used. From the viewpoint of obtaining a coating film with a better appearance and a coating film with better mechanical properties, at least one selected from the group consisting of acetic acid and 2-ethylhexanoic acid may be used.

[0073] Carboxylic acid anhydrides have at least one acid anhydride group (-COOCO-). The number of acid anhydride groups in a carboxylic acid anhydride may be one or more. From the viewpoint of reducing the rate of change in viscosity over time, the carboxylic acid anhydride may be a compound represented by the following formula (C-2). [ka]

[0074] In formula (C-2), R 2c and R 3c each independently represents an alkyl group having 1 to 5 carbon atoms. Examples of the alkyl group represented by R 2c and R 3c are the same as the examples of the alkyl group having 1 to 5 carbon atoms among the alkyl groups represented by R 1c R 2c and R 3c may be the same as or different from each other.

[0075] Specific examples of the carboxylic acid anhydride include acetic anhydride, propanoic anhydride, butanoic anhydride, etc. These can be used alone or in combination of two or more. From the viewpoint of further reducing the change rate of viscosity over time, acetic anhydride may be used.

[0076] β-diketone is a compound having a structure (-COCH2CO-) in which two ketones are bonded via a methylene group. β-diketone may be a compound represented by the following formula (C-3) from the viewpoint of further reducing the change rate of viscosity over time.

Chemical formula

[0077] In formula (C-3), R 4c and R 5c each independently represents an alkyl group having 1 to 5 carbon atoms. Examples of the alkyl group represented by R 4c and R 5c are the same as the examples of the alkyl group having 1 to 5 carbon atoms among the alkyl groups represented by R 1c R 4c and R 5c may be the same as or different from each other.

[0078] Specific examples of β-diketones include acetylacetone. These can be used individually or in combination of two or more. From the viewpoint of further reducing the rate of change in viscosity over time, acetylacetone may be used.

[0079] Component (C) may contain at least one selected from the group consisting of carboxylic acids and β-diketones, from the viewpoint of reducing the rate of change in viscosity over time, and may contain at least one selected from the group consisting of compounds represented by formula (C-1) and compounds represented by formula (C-3), and may contain at least one selected from the group consisting of 2-ethylhexanoic acid, isobutanoic acid, isopentanoic acid, and acetylacetone.

[0080] The molecular weight of component (C) may be, for example, 60 to 400, or 80 to 300 or 100 to 200. If component (C) contains multiple compounds, the number average molecular weight of the multiple compounds may be within the above range.

[0081] From the viewpoint of reducing the rate of change in viscosity over time, the content of component (C) may be 0.1 parts by mass or more, 0.3 parts by mass or more, 0.5 parts by mass or more, or 0.8 parts by mass or more per 100 parts by mass of component (A). From the viewpoint of making it easier to obtain a coating film with superior mechanical properties, the content of component (C) may be 1.5 parts by mass or less, 1.0 part by mass or less, or 0.6 parts by mass or less per 100 parts by mass of component (A). From these viewpoints, the content of component (C) may be 0.1 to 1.5 parts by mass, 0.3 to 1.0 parts by mass, 0.5 to 1.5 parts by mass, 0.8 to 1.5 parts by mass, or 0.1 to 0.6 parts by mass per 100 parts by mass of component (A).

[0082] The content of component (C) may be 1.0 mmol or more, 1.5 mmol or more, 2.0 mmol or more, 2.5 mmol or more, or 3.0 mmol or more per 100 g of component (A) from the viewpoint of reducing the rate of change in viscosity over time. The content of component (C) may be 20.0 mmol or less, 16.0 mmol or less, 12.0 mmol or less, 10.0 mmol or less, or 8.0 mmol or less per 100 g of component (A) from the viewpoint of making it easier to obtain a coating film with superior mechanical properties and promoting the reaction between the polyol and the isocyanate. From these perspectives, the content of component (C) may be 1.0-20.0 mmol, 1.0-16.0 mmol, 1.0-12.0 mmol, 1.5-12.0 mmol, 2.0-10.0 mmol, 2.5-10.0 mmol, or 3.0-8.0 mmol per 100 g of component (A).

[0083] The content of component (C) may be 0.1 mol or more, 1.0 mol or more, 1.5 mol or more, 2.0 mol or more, 2.5 mol or more, 3.0 mol or more, or 3.5 mol or more per 1.0 mol of component (B), from the viewpoint of reducing the rate of change in viscosity over time. The content of component (C) may be 30.0 mol or less, 20.0 mol or less, 15.0 mol or less, 12.0 mol or less, 11.0 mol or less, 10.0 mol or less, or 8.0 mol or less per 1.0 mol of component (B), from the viewpoint of making it easier to obtain a coating film with superior mechanical properties and promoting the reaction between the polyol and the isocyanate. From these perspectives, the content of component (C) may be 0.1 to 30.0 mol, 1.0 to 20.0 mol, 1.5 to 15.0 mol, 2.0 to 12.0 mol, 2.5 to 11.0 mol, 3.0 to 10.0 mol, or 3.5 to 8.0 mol per 1.0 mol of component (B).

[0084] [(D) component] Component (D) (hindered amine-based light stabilizer) is an additive that enhances the light stability of the resin by capturing radicals, which are factors that degrade the resin. Component (D) has a hindered amine structure represented by the following formula (D-1), for example. [ka]

[0085] In formula (D-1), X represents a substituent such as a hydrogen atom or hydrocarbon group, and * represents a bond.

[0086] (D) A wide range of known hindered amine-based light stabilizers used in the field of resin materials can be used as component (D). From the viewpoint of obtaining better solubility in component (A) and better weather resistance, a compound in which X in formula (D-1) is a methyl group (i.e., a compound having the structure represented by the following formula (D-2)) may be used. [ka]

[0087] The molecular weight of component (D) may be, for example, 400 to 4000. From the viewpoint of superior solubility in component (A), the molecular weight of component (D) may be less than 1000, 700 or less, or 500 or less, or 400 or more and less than 1000, 400 to 700, or 400 to 500. Here, if component (D) contains multiple compounds, the weight-average molecular weight of the multiple compounds may be within the above range.

[0088] The base constant (pKb) of component (D) may be, for example, 4 to 12, and from the viewpoint of superior solubility with respect to component (A), it may be 4 to 9.

[0089] (D)Specific examples of component 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 from BASF), and a reaction product of 1,2,3,4-butanetetracarboxylic acid tetramethyl ester, 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 from ADEKA Corporation). Examples include LA-63P, bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate (Tinuvin 770 from 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 from BASF).

[0090] From the viewpoint of superior weather resistance (especially gloss retention), the content of component (D) may be 0.05 parts by mass or more, 0.1 parts by mass or more, or 0.2 parts by mass or more, per 100 parts by mass of component (A). From the viewpoint of superior mechanical properties, the content of component (D) may be 5 parts by mass or less, 3 parts by mass or less, or 2 parts by mass or less, per 100 parts by mass of component (A). From the above viewpoint, the content of component (D) may be 0.05 to 5 parts by mass, 0.1 to 3 parts by mass or 0.2 to 2 parts by mass, per 100 parts by mass of component (A).

[0091] [(E) component] The polyol composition may further contain (E) an ultraviolet absorber (hereinafter also referred to as "component (E)"). The ultraviolet absorber is an additive that has the function of absorbing ultraviolet light. Examples of component (E) include triazine-based ultraviolet absorbers and oxalic acid anilide-based ultraviolet absorbers. These may be used individually or in combination of two or more. From the viewpoint of superior solubility with component (A), component (E) may contain a triazine-based ultraviolet absorber.

[0092] As the triazine-based ultraviolet absorber, a wide range of known triazine-based ultraviolet absorbers used in the field of resin materials can be used. From the viewpoint of obtaining better solubility in component (A) and better weather resistance, a compound represented by the following formula (E-1) may be used. [ka]

[0093] In formula (E-1), R 1 R represents a hydrocarbon group with 1 to 15 carbon atoms. 2 ~R 5 Each of these independently represents a hydrogen atom, a hydroxyl group, a methyl group, or an ethyl group. 1 The hydrogen atoms in the hydrocarbon group represented by may be substituted with hydroxyl groups, or with alkoxy groups having 1 to 15 carbon atoms. 2 ~R 5 This may be a hydrogen atom, a methyl group, or an ethyl group, and may be a methyl group or an ethyl group, or it 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.

[0094] R 1The hydrocarbon group represented by may be, for example, an alkyl group. Examples of alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, pentyl, hexyl, heptyl, octyl, 2-ethylhexyl, nonyl, decyl, undecyl, dodecyl, tetradecyl, and pentadecyl groups. The hydrogen atoms of these alkyl groups may be substituted with hydroxyl groups, or with alkoxy groups having 1 to 15 carbon atoms. Examples of alkoxy groups having 1 to 15 carbon atoms include methoxy, ethoxy, propyloxy, isopropyloxy, butyloxy, isobutyloxy, t-butyloxy, pentyloxy, hexyloxy, heptyloxy, octyloxy, 2-ethylhexyloxy, nonyloxy, decyloxy, undecyloxy, dodecyloxy, tetradecyloxy, and pentadecyloxy groups.

[0095] Triazine-based ultraviolet absorbers may contain a compound represented by the following formula (E-2) in order to improve solubility in component (A) and reduce precipitation at low temperatures (improve low-temperature stability). [ka]

[0096] In formula (E-2), R 11 R represents an alkyl group having 1 to 15 carbon atoms. 2 ~R 5 This is R in equation (E-1). 2 ~R 5 This is synonymous with R. 11 Examples of alkyl groups represented by R include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, t-butyl group, pentyl group, hexyl group, heptyl group, octyl group, 2-ethylhexyl group, nonyl group, decyl group, undecyl group, dodecyl group, tetradecyl group, pentadecyl group, etc. 11The alkyl group represented by may be a methyl group, from the viewpoint of further improving solubility in component (A) and low-temperature stability.

[0097] Specific examples of triazine-based UV 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 from BASF), 2-(4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine-2-yl)-5-(octyloxy)phenol), and 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 from BASF), and 2-[4-[4,6-bis(biphenyl-4-yl)-1,3,5-triazine-2-yl]-3-hydroxyphenoxy]propane 6-methylheptyl (Tinuvin 479 from BASF).

[0098] From the viewpoint of superior weather resistance (especially resistance to yellowing), the content of component (E) may be 0.05 parts by mass or more per 100 parts by mass of component (A), and from the viewpoint of superior mechanical properties, it may be 5 parts by mass or less per 100 parts by mass of component (A). From these viewpoints, the content of component (E) may be 0.05 to 5 parts by mass per 100 parts by mass of component (A). From the same viewpoint as above, the content of component (E) may be 0.1 parts by mass or more or 0.2 parts by mass or more, 3 parts by mass or less or 2 parts by mass or less, or 0.1 to 3 parts by mass or 0.2 to 2 parts by mass per 100 parts by mass of component (A).

[0099] From the viewpoint of superior weather resistance, the total content of component (D) and component (E) 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 component (A). From the viewpoint of superior mechanical properties, the total content of component (D) and component (E) may be 8 parts by mass or less, 5 parts by mass or less, or 3 parts by mass or less, per 100 parts by mass of component (A). From the above viewpoint, the total content of component (C) and component (D) may be 0.5 to 8 parts by mass, 0.6 to 5 parts by mass or 0.7 to 3 parts by mass, per 100 parts by mass of component (A).

[0100] [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; and Solvesso #100 and Solvesso #150 (both trade names, manufactured by ExxonMobil). Note that volatile organic compounds can also be components (A) to (E). That is, even if a compound falls under components (A) to (E), if its boiling point at 1 atm is 180°C or lower, it is considered a volatile organic compound.

[0101] The content of volatile organic compounds is 0 to 10% by mass, based on the total mass of the polyol composition. Good in-mold coating properties can be obtained by having the content of volatile organic compounds within the above range. The content of volatile organic compounds may be 5% by mass or less, 1% by mass or less, or 0.1% by mass or less, based on the total mass of the polyol composition. When a volatile organic compound is used as component (C), the content of the volatile organic compound may be 0.1 parts by mass or more, 0.3 parts by mass or more, 0.5 parts by mass or more, or 0.8 parts by mass or more, 1.5 parts by mass or less, 1.0 parts by mass or less, or 0.6 parts by mass or less, 0.1 to 1.5 parts by mass, 0.3 to 1.0 parts by mass, 0.5 to 1.5 parts by mass, 0.8 to 1.5 parts by mass, or 0.1 to 0.6 parts by mass, based on 100 parts by mass of component (A).

[0102] [Other ingredients] The polyol composition may further contain other components besides those described above. Examples of other components include antioxidants such as 2,6-di-tert-butyl-4-methylphenol, pigments, dyes, flame retardants, hydrolysis inhibitors, lubricants, plasticizers, fillers, antistatic agents, dispersants, storage stabilizers, thickeners, internal release agents, surface modifiers, defoamers, and antibacterial agents.

[0103] The polyol composition may further contain hydroxyl group-containing compounds other than component (A) (compounds having hydroxyl groups) as other components. However, from the viewpoint of obtaining better transparency, the polyol composition does not need to contain hydroxyl group-containing compounds having aromatic rings. The content of hydroxyl group-containing compounds having aromatic rings may be 5% by mass or less, or 0% by mass, based on the total mass of the polyol composition.

[0104] The viscosity of the polyol composition at 25°C may be 10 to 10,000 mPa·s, 50 to 8,000 mPa·s, 100 to 5,000 mPa·s, or 200 to 2,000 mPa·s. When the viscosity of the first component at 25°C is within the above range, a polyurethane resin-forming composition with superior film-forming properties is more likely to be obtained. In this specification, the viscosity at 25°C is a value measured using a B-type viscometer.

[0105] <Polyurethane resin-forming composition> Another embodiment of the present disclosure relates to a polyurethane resin-forming composition containing the above-described components (A) to (D) and (F) polyisocyanate (hereinafter also referred to as "component (F)"), wherein the content of volatile organic compounds (based on the total mass of the polyurethane resin-forming composition) is 0 to 10% by mass.

[0106] The above polyurethane resin-forming composition facilitates the formation of a coating film with excellent weather resistance during in-mold painting. Therefore, the above polyurethane resin-forming composition is suitably used as a coating agent for in-mold painting (in-mold coating agent), and is particularly suitable for use as a coating agent for plastic molded products used in the interior and exterior parts of automobiles.

[0107] Furthermore, the coating film formed by the above polyurethane resin-forming composition tends to have excellent self-healing properties. While self-healing properties of the coating film are not always necessary, they may be beneficial in applications of plastic molded products used in automotive interior and exterior parts.

[0108] The details of components (A) to (D) contained in the polyurethane resin-forming composition are the same as the details of components (A) to (D) contained in the polyol composition of the above embodiment. The polyurethane resin-forming composition may further contain components other than components (A) to (D) that may be contained in the polyol composition of the above embodiment (component (E), other components).

[0109] The polyurethane resin-forming composition may contain the polyol composition of the above embodiment. That is, the polyurethane resin-forming composition may be a mixture of the polyol composition of the above embodiment, component (F), and other components that are optionally added. In this case, the content of the polyol composition may be, for example, 10 to 80% by mass, 20 to 70% by mass, or 30 to 60% by mass, based on the total mass of the polyurethane resin-forming composition.

[0110] The content of volatile organic compounds in the polyurethane resin-forming composition (based on the total mass of the polyurethane resin-forming composition) is 0 to 10% by mass. Good in-mold coating properties can be obtained by having the content of volatile organic compounds within the above range. The content of volatile organic compounds may be 5% by mass or less, 1% by mass or less, or 0.1% by mass or less, based on the total mass of the polyurethane resin-forming composition. When a volatile organic compound is used as component (C), the content of the volatile organic compound may be 0.1 parts by mass or more, 0.3 parts by mass or more, 0.5 parts by mass or more, or 0.8 parts by mass or more, 1.5 parts by mass or less, 1.0 parts by mass or less, or 0.6 parts by mass or less, 0.1 to 1.5 parts by mass, 0.3 to 1.0 parts by mass, 0.5 to 1.5 parts by mass, 0.8 to 1.5 parts by mass, or 0.1 to 0.6 parts by mass, per 100 parts by mass of component (A).

[0111] [(F) Ingredient: Polyisocyanate] Polyisocyanates are compounds having multiple isocyanate groups (-NCO). Component (F) may be a single polyisocyanate or a combination of two or more polyisocyanates.

[0112] Component (F) may be liquid at 25°C from the viewpoint of superior film-forming properties in in-mold coating.

[0113] Component (F) may include a non-aromatic polyisocyanate to further improve the weather resistance (especially resistance to yellowing) of the coating film. In this specification, "non-aromatic polyisocyanate" means a polyisocyanate that does not have an aromatic ring (e.g., a benzene ring).

[0114] Examples of non-aromatic polyisocyanates include aliphatic polyisocyanates, alicyclic polyisocyanates, and modified versions thereof. Modified versions may be included from the viewpoint of improving miscibility with polyols, curing of the polyurethane resin-forming composition with shorter heating times, obtaining coatings with superior mechanical properties, and obtaining superior weather resistance and hydrolysis resistance. Examples of modified versions include isocyanurate modified versions, allophanate modified versions, biuret modified versions, urethane modified versions, urea modified versions, carbodiimide modified versions, uretonimine modified versions, uretdione modified versions, iminooxadiazine modified versions, and the like.

[0115] 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-trimethylhexamethylene diisocyanate. Examples 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, and 2-isocyanate propyl-2,6-diisocyanate hexanoate. These may be used individually or in combination of two or more.

[0116] Examples of alicyclic polyisocyanates include isophorone diisocyanate, cyclohexyl diisocyanate, bis(isocyanate-methyl)cyclohexane, dicyclohexylmethane diisocyanate, methylcyclohexane diisocyanate, dicyclohexyldimethylmethane diisocyanate, 2,2'-dimethyldicyclohexylmethane diisocyanate, bis(4-isocyanate-n-butylidene)pentaerythritol, and hydrogenated dimer acid diisocyanate. , 2-isocyanatemethyl-3-(3-isocyanatetopropyl)-5-isocyanatemethyl-bicyclo[2.2.1]-heptane, 2-isocyanatemethyl-3-(3-isocyanatetopropyl)-6-isocyanatemethyl-bicyclo[2.2.1]-heptane, 2-isocyanatemethyl-2-(3-isocyanatetopropyl)-5-isocyanatemethyl-bicyclo[2.2.1]-heptane, 2-isocyanatemethyl-2-(3-isocyanatepropyl (L)-6-isocyanatemethyl-bicyclo[2.2.1]-heptane, 2-isocyanatemethyl-3-(3-isocyanatetopropyl)-5-(2-isocyanateethyl)-bicyclo-[2.2.1]-heptane, 2-isocyanatemethyl-3-(3-isocyanatetopropyl)-6-(2-isocyanateethyl)-bicyclo-[2.2.1]-heptane, 2-isocyanatemethyl-2-(3-isocyanatetopropyl)-5-(2-isocyanateethyl) Examples include bicyclo-[2.2.1]-heptane, 2-isocyanatemethyl-2-(3-isocyanatetopropyl)-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, and hydrogenated tetramethylxylene diisocyanate. These may be used individually or in combination of two or more.

[0117] Among the polyisocyanates mentioned above, when component (F) contains an isocyanurate modified aliphatic diisocyanate, the curability (e.g., low-temperature rapid curing) tends to be further improved. From the viewpoint of further improving curability, the content of the above isocyanurate modified aliphatic diisocyanate in component (F) may be 10% by mass or more, 30% by mass or more, or 50% by mass or more, or 100% by mass or less, 90% by mass or less, or 70% by mass or less, or 10 to 100% by mass, 30 to 90% by mass, or 50 to 70% by mass. Note that the above content is based on the total mass of component (F).

[0118] If component (F) contains an isocyanurate modified aliphatic diisocyanate, component (F) may also contain modified non-aromatic polyisocyanates other than the isocyanurate modified aliphatic diisocyanate, to the extent that it does not impair the purpose of this disclosure. The content of modified non-aromatic polyisocyanates other than the isocyanurate modified aliphatic diisocyanate in component (F) may be 90% by mass or less, 70% by mass or less, 50% by mass or less, 30% by mass or less, or 10% by mass or less, and may also be 0% by mass. The above content is based on the total mass of component (F).

[0119] The NCO content of component (F) may be 10 to 40% by mass, and may also be 15 to 35% by mass or 19 to 30% by mass. When the NCO content of component (F) is 10% by mass or more, the coating film tends to have higher hardness. When the NCO content of component (F) is 40% by mass or less, the coating film tends to exhibit good self-healing properties. The above content is based on the total mass of component (F).

[0120] In this specification, the NCO content is the value measured by the method described in JIS K1603-1 (Test method for aromatic isocyanates in polyurethane raw materials).

[0121] The viscosity of the polyisocyanate at 25°C may be 10 to 10,000 mPa·s, and may also be 50 to 8,000 mPa·s, 100 to 5,000 mPa·s, or 200 to 2,000 mPa·s. When the viscosity of the polyisocyanate at 25°C is within the above range, a polyurethane resin-forming composition (coating agent) with even better film-forming properties is more likely to be obtained.

[0122] The content of component (F) may be, for example, 20 to 90% by mass, 30 to 80% by mass, or 40 to 70% by mass, based on the total mass of the polyurethane resin-forming composition.

[0123] The polyurethane resin-forming composition may further contain isocyanate group-containing compounds other than component (F). However, from the viewpoint of obtaining better transparency, the polyurethane resin-forming composition does not need to contain isocyanate group-containing compounds having aromatic rings. The content of isocyanate group-containing compounds having aromatic rings may be 5% by mass or less, or 0% by mass, based on the total mass of the polyurethane resin-forming composition.

[0124] The ratio of the number of moles of isocyanate groups in the isocyanate group-containing compound contained in the polyurethane resin-forming composition to the number of moles of hydroxyl groups in the hydroxyl group-containing compound contained in the polyurethane resin-forming composition (NCO / OH equivalent) may be 0.8 or higher, 0.9 or higher, or 1.0 or higher, from the viewpoint of suppressing excess hydroxyl groups and further improving the durability and mechanical properties of the coating film. The NCO / OH equivalent may be 1.3 or lower, 1.2 or lower, or 1.1 or lower, from the viewpoint of suppressing excess isocyanate groups and further improving the durability and mechanical properties of the coating film. The NCO / OH equivalent may be 0.8 to 1.3, 0.9 to 1.2, or 1.0 to 1.1, from the above viewpoint.

[0125] <In-mold coating agent set> Another embodiment of the present disclosure relates to a coating set for preparing the polyurethane resin-forming composition of the above embodiment. The coating set is, for example, a coating set for in-mold coating. The coating set comprises a first agent containing the above components (A), (B), (C), and (D), and a second agent containing the above component (F). The first agent may be the polyol composition of the above embodiment. When the coating set consists of a first agent and a second agent, the polyurethane resin-forming composition of the above embodiment can be prepared by mixing the first agent and the second agent.

[0126] The first component of the above coating agent set contains components (A), (B), (C), and (D). However, since the additive component (D) dissolves easily in component (A), the first component can be prepared at a relatively low temperature (e.g., below 100°C).

[0127] The first and second agents may contain component (E) above, and may also contain other components that can be contained in the polyurethane resin-forming composition. However, from the viewpoint of storage stability, hydroxyl group-containing compounds other than component (A) may be incorporated into the first agent, and isocyanate group-containing compounds other than component (F) may be incorporated into the second agent.

[0128] The coating set may further comprise other agents different from the first and second agents. These other agents may contain other components that can be included in the polyurethane resin-forming composition, and may contain component (E). If the coating set further comprises other agents, the polyurethane resin-forming composition of the above embodiment can be prepared by mixing the first agent, the second agent, and the other agents.

[0129] The viscosity of the first component at 25°C may be 10 to 10,000 mPa·s, and may also be 50 to 8,000 mPa·s, 100 to 5,000 mPa·s, or 200 to 2,000 mPa·s. When the viscosity of the first component at 25°C is within the above range, a polyurethane resin-forming composition (coating agent) with even better film-forming properties is more likely to be obtained.

[0130] The viscosity of the second component at 25°C may be 10 to 10,000 mPa·s, and may also be 50 to 8,000 mPa·s, 100 to 5,000 mPa·s, or 200 to 2,000 mPa·s. When the viscosity of the second component at 25°C is within the above range, a polyurethane resin-forming composition (coating agent) with even better film-forming properties is more likely to be obtained.

[0131] When using the in-mold coating set, for example, the first agent, the second agent, and any other agents used may be mixed so that the NCO / OH equivalent is within the range described above.

[0132] <coating film> Another embodiment of the present disclosure relates to a coating film comprising a reaction product of the polyurethane resin-forming composition of the above embodiment. Here, the reaction product of the polyurethane resin-forming composition is a reaction product obtained by reacting components (at least component (A) and component (F)) contained in the polyurethane resin-forming composition. Therefore, the coating film contains a polyurethane resin produced by the reaction of at least component (A) and component (F). The coating film may also contain some of the components (e.g., unreacted components) contained in the polyurethane resin-forming composition.

[0133] The thickness of the coating film is, for example, 1 to 10,000 μm, and may also be 5 to 5,000 μm or 10 to 1,000 μm.

[0134] The coating film can be formed by first forming a coating film made of the polyurethane resin-forming 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 later. Since the reaction of the polyurethane resin-forming composition causes the coating film made of the composition to harden, the coating film made of the polyurethane resin-forming composition and the coating film of the above embodiment can also be referred to as the uncured film and the cured film, respectively.

[0135] The coating film may be provided on a substrate such as a plastic molded product and constitute a part of a component including the substrate (for example, an interior part of an automobile). That is, as another embodiment, the present disclosure provides a component comprising a substrate and the coating film provided on the substrate.

[0136] <In-mold coating method> Another embodiment of the present disclosure relates to an in-mold coating method comprising: preparing a substrate and a mold in which the substrate is placed; injecting the polyurethane resin-forming composition of the above embodiment into the mold; applying the polyurethane resin-forming composition to the surface of the substrate; and reacting the polyurethane resin-forming composition to form a coating film on the surface of the substrate. According to this method, the coating film of the above embodiment can be obtained. The in-mold coating method of this embodiment will now be described with reference to Figure 1.

[0137] Figure 1 is a schematic diagram illustrating one embodiment of the in-mold coating method. In the in-mold coating method of this embodiment, first, a substrate 1 and a mold 2 in which the substrate 1 is placed are prepared (see Figure 1(a)).

[0138] The base material 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 surface treatment such as corona discharge treatment. Other coatings that can serve as intermediate layers may be formed on the surface of the molded body.

[0139] Mold 2 has a gap 2a for forming a coating film between the inner wall of mold 2 and the base material 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. Mold 2 may be the same mold used to mold the base material 1, and may have an internal structure that is the same shape as the target base material 1. In this case, for example, after injecting a plastic material heated and melted in an injection cylinder into mold 2, cooling and pressurizing to mold the base material 1, the clamping force may be reduced, or the gap between the resulting molded product (base material) and the inner wall of the mold may be slightly opened to provide a gap 2a for forming a coating film between the base material 1 and mold 2.

[0140] Next, the composition 6 (polyurethane resin-forming composition) of the above embodiment is prepared by supplying the first agent 3 and the second agent 4 into the tank 5 and mixing them, and the composition 6 is injected into the mold 2 to coat the surface 1a of the substrate 1 with composition 6 (see Figure 1(b)). When preparing composition 6, the first agent 3 and the second agent 4 may be heated to mix them more uniformly. Also, when injecting composition 6, composition 6 and the mold 2 may be heated to the extent that composition 6 does not become excessively viscous. However, the temperature of composition 6 at the time of injection may be 30°C or less, and the temperature of the mold 2 at the time of injection may be 85°C or less.

[0141] Next, by reacting composition 6, a coating film 7 (e.g., a cured film) containing the reaction products of composition 6 is formed on the surface of the substrate 1 (see Figure 1(c)). The reaction of composition 6 may be carried out by injecting composition 6 into a heated mold. The heating temperature should not exceed the heat resistance of the substrate, and from the viewpoint of coating film formation, it may be 50 to 150°C or 50 to 85°C. In order to allow the reaction of composition 6 to proceed more sufficiently, the coating film may be heated again after the substrate is removed from the mold. [Examples]

[0142] The contents of this disclosure will be described in more detail below using examples and comparative examples, but this disclosure is not limited to the following examples.

[0143] <Synthesis and Evaluation of Polycarbonate Polyols> (Synthesis Example 1) In a reaction apparatus equipped with a stirrer, thermometer, heating device, and distillation column, 792g of 3-methyl-1,5-pentanediol (manufactured by Kuraray Co., Ltd.) and 88g of 1,6-hexanediol (manufactured by Tokyo Chemical Industry Co., Ltd.) were charged as polyol components (a mixture of polyols), 638g of diethyl carbonate (manufactured by Tokyo Chemical Industry Co., Ltd.) was charged as the carbonate component, and 0.05g of tetrabutyl titanate was charged as a reaction catalyst. The temperature inside the apparatus was gradually increased to 190°C under a nitrogen stream. When the distillation of ethanol slowed down and the temperature at the top of the distillation column fell below 50°C, the temperature inside the apparatus was kept at 190°C and the pressure was gradually reduced to 0.1kPa. The reaction was continued at a pressure of 0.1kPa for another 5 hours to distill off the ethanol. This synthesized the polycarbonate polyol (PCP) of Synthesis Example 1.

[0144] (Condition evaluation) The obtained polycarbonate polyol was heated to 100°C, then placed in a transparent glass bottle and left to stand for 24 hours at 25°C. After standing, the polycarbonate polyol was visually observed to determine its fluidity when the glass bottle was tilted at 25°C. It was confirmed that the polycarbonate polyol was fluid (i.e., liquid).

[0145] (Hydroxyl value measurement) The hydroxyl value of the polycarbonate polyol obtained in Synthesis Example 1 was evaluated using an acetylation reagent in accordance with JIS K1557-1. Furthermore, based on the hydroxyl value, the molecular weight of the polycarbonate polyol was calculated using a theoretical value (calculated value) of 2 for the number of hydroxyl groups. The hydroxyl value of the polycarbonate polyol was 226.8 mgKOH / g, and the molecular weight calculated from the hydroxyl value and number of hydroxyl groups was 495.

[0146] <Examples 1-11 and Comparative Examples 1-7> (Preparation of polyol composition) In a plastic bottle, components (A) (polyol), (B) (urethane-based metal catalyst), (C) (carbonyl compound), (D) (hindered amine-based light stabilizer), and (E) (ultraviolet absorber) shown in Tables 1 and 2 were charged in the mixing ratios (mass%) shown in Tables 1 and 2. After replacing the atmosphere with nitrogen by flowing an appropriate amount of nitrogen into the plastic bottle, it was sealed. The contents were mixed using a mixing rotor to obtain a polyol composition. In Tables 1 and 2, "(C)mol / (B)mol" indicates the ratio of the content of component (C) per 1 mol of (B) (unit: moles).

[0147] (Calculation of average hydroxyl value) The average hydroxyl value of component (A) in the polyol composition was calculated using the following formula. The results are shown in Tables 1 and 2. Average hydroxyl value = (Hydroxyl value of component (A) 1 × Mass of component (A) 1 added + Hydroxyl value of component (A) 2 × Mass of component (A) 2 added) / Total mass of component (A) added Here, (A) component 1 and (A) component 2 refer to the respective materials blended as component (A). For example, in Example 1, component (A) 1 is "PCP" in the table, and component (A) 2 is "1,3-BG" in the table.

[0148] (Evaluation of viscosity and storage stability of polyol compositions) Polyol compositions prepared and stored within 24 hours at 23-25°C were placed in glass bottles (manufactured by AS ONE Corporation, standard bottle No. 11), and the glass bottles were immersed in a constant temperature water bath at 25°C for 5 hours. Subsequently, the viscosity (unit: mPa·s) of the polyol composition at 25°C was measured using a B-type viscometer (manufactured by Toki Sangyo Co., Ltd., TVB-22L) (initial viscosity V1).

[0149] Meanwhile, the viscosity (unit: mPa·s) at 25°C was similarly measured for polyol compositions stored for 4 weeks in an explosion-proof constant temperature bath at 45°C (viscosity V2 after 4 weeks of storage at 45°C). The 4-week storage was carried out by placing 200g of the polyol composition into a 250mL square can (manufactured by Seibu Container Co., Ltd.), replacing the atmosphere inside the can with nitrogen, sealing it, and storing the can in an explosion-proof constant temperature bath at 45°C for 4 weeks.

[0150] The viscosity change rate of the polyol composition after storage at 45°C for 4 weeks was calculated using the following formula. Viscosity change rate (%)=100×[(V2-V1) / (V1)]

[0151] [Evaluation Criteria for Viscosity Change Rate] The viscosity change rate was evaluated according to the following criteria. A: The absolute value of the viscosity change rate is less than 6. B: The absolute value of the viscosity change rate is 6 or more and less than 10. • C: The absolute value of the viscosity change rate is 10 or more and less than 13. • D: The absolute value of the viscosity change rate is 13 or greater.

[0152] (Preparation and reactivity evaluation of polyurethane resin-forming compositions) As the first component, a polyol composition was prepared, stored within 24 hours at 23-25°C after preparation. As the second component, Coronate HXLV (referred to as "C-HXLV" in the table), which is component (F) (polyisocyanate), was prepared. The first and second components were placed in a stirring container for Awatori Rentaro (manufactured by Thinky Co., Ltd., No. 001, capacity 150 mL) in the mixing ratio (mass%) shown in Tables 1 and 2, with a total amount of 57 g. The ratio of OH groups in component (A) (polyol) to NCO groups in component (B) (polyisocyanate) was set to NCO / OH = 1.05. Immediately after preparation, the mixture of the first and second components was mixed for 30 seconds at a speed of 2000 rpm in a rotation-and-revolution type mixer (manufactured by Thinky Co., Ltd., product name: Awatori Rentaro ARE-310) to prepare a liquid polyurethane resin-forming composition. Next, with the time immediately after mixing for 30 seconds set as 0 seconds, the fluidity near the surface of the polyurethane resin-forming composition was checked with a wooden stirrer every 5 seconds, and the time until the polyurethane resin-forming composition became solid (initial reactivity R1, in seconds) was measured.

[0153] Polyol compositions stored in an explosion-proof constant temperature chamber at 45°C for 4 weeks were also allowed to stand for 16 to 24 hours in an environment of 23 to 25°C, and then mixed with the second agent (Coronate HXLV) in the same manner as above to prepare a polyurethane resin-forming composition. Subsequently, the time until the polyurethane resin-forming composition became solid (reactivity R2 after 4 weeks of storage at 45°C, in seconds) was measured in the same manner as above.

[0154] The rate of change in the reactivity of a polyurethane resin-forming composition after storing a polyol composition at 45°C for 4 weeks was calculated using the following formula. Reactivity change rate (%) = 100 × [(R2 - R1) / (R1)]

[0155] [Criteria for evaluating initial reactivity] Initial reactivity was evaluated according to the following criteria. Note that if the viscosity change rate evaluation result was D, this evaluation was not performed. A: R1 is between 5 seconds and 60 seconds. • B:R1 is greater than 60 seconds but less than or equal to 90 seconds • C:R1 is greater than 90 seconds but less than or equal to 120 seconds. • D:R1 is less than 5 seconds or greater than 120 seconds

[0156] [Evaluation Criteria for Reactivity Change Rate] The rate of change in reactivity was evaluated according to the following criteria. Note that if the initial reactivity evaluation result was D, this evaluation was not performed. A: The absolute value of the rate of change of reactivity is 20 or less. B: The absolute value of the rate of change of reactivity is greater than 20 and less than or equal to 30. • C: The absolute value of the rate of change of reactivity is greater than 30 and less than or equal to 40. • D: The absolute value of the rate of change of reactivity is greater than 40

[0157] (Preparation of polyurethane resin-forming compositions and fabrication of coating films) The first and second agents were mixed for 30 seconds in the same manner as in the above-mentioned reactivity evaluation to prepare a liquid polyurethane resin-forming composition. Next, the coating liquid consisting of the obtained polyurethane resin-forming composition was applied to a white steel plate, which served as the substrate. At this time, two guides with a height of 600 μm were placed on the substrate, and the coating liquid was poured between the two guides to adjust the cured film thickness to 600 μm. To reproduce the conditions of in-mold coating, release glass was placed on the guides so as to cover the coating film (uncured film consisting of the coating liquid), and then the coating film was cured at 80°C for 1 hour. For coating films consisting of polyurethane resin-forming compositions that received a D rating for initial reactivity in the above-mentioned reactivity evaluation, the film was cured at 80°C for 20 hours. After that, the film was cured at 50°C for 6 hours to form a coating film (cured film) containing the reaction products of the polyurethane resin-forming composition. The laminate consisting of the substrate and coating film (cured film) obtained in this manner was used as a test piece and the following evaluation was performed.

[0158] (Weathering test) The test specimens obtained above were subjected to a 576-hour weathering test 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: 0.62W / m²) 2 (80°C; 50°C during condensation, light exposure / condensation cycle = 20 hours / 4 hours)

[0159] (Evaluation of gloss retention) Using Microtrigloss (manufactured by Big Chemie Co., Ltd.), the glossiness at 60° before and after the weather resistance test of the test specimens obtained above was measured, and the glossiness retention rate was calculated using the formula shown below. Gloss retention rate (%) = 100 × [(Gloss of test specimen after weathering test) / (Gloss of test specimen before weathering test)]

[0160] [Evaluation criteria for 60° gloss retention rate] The 60° gloss retention rate was evaluated according to the following criteria. A: Gloss retention rate of 90% or more B: Gloss retention rate is 80% or more but less than 90% • C: Gloss retention rate is 60% or more but less than 80% • D: Gloss retention rate is less than 60%

[0161] [Table 1]

[0162] [Table 2]

[0163] The details of the materials shown in Tables 1 and 2 are as follows: • PCP: Polycarbonate polyol from synthesis example 1 • PEP: Polyester polyol (manufactured by Kuraray Co., Ltd., product name: Kuraray Polyol P-510, hydroxyl group count: 2, hydroxyl value: 226 mg KOH / g) • 1,3-BG: 1,3-butanediol (manufactured by Daicel Corporation, 2 hydroxyl groups, hydroxyl value 1245 mgKOH / g) • MPD: 2-methyl-1,3-propanediol (manufactured by Sigma-Aldrich, 2 hydroxyl groups, hydroxyl value 1245 mgKOH / g) • DBTDL: Dibutyltin dilaurate (manufactured by Nitto Chemical Co., Ltd., product name: Neostan U-100, molecular weight: 631.56) • Acetic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., molecular weight: 60.05) • Acetic anhydride (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., molecular weight: 102.09) • 2-Ethylhexanoic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., molecular weight: 144.21) • Acetylacetone (manufactured by Daicel Corporation, molecular weight: 100.12) Methyl acetoacetate (manufactured by Daicel Corporation) • Phosphate (manufactured by Kishida Chemical Co., Ltd.) • HALS(1): Tinuvin 292 (BASF, molecular weight 509, 370 (mixture), N-CH3 type HALS) • Triazine (1): Tinuvin 400 (BASF, a 1-methoxy-2-propanol solution of the reaction product of 4-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl]benzene-1,3-diol, 2-[(dodecyloxy)methyl]oxirane, and 2-[(alkyl(C=10~16)oxy)methyl]oxirane) • C-HXLV: Isocyanurate modified form of hexamethylene diisocyanate (manufactured by Tosoh Corporation, product name: Coronate HXLV (NCO content 23.4% by mass), viscosity at 25°C: 1100 mPa·s, liquid at 25°C) [Explanation of Symbols]

[0164] 1...Substrate, 2...Mold, 3...First agent, 4...Second agent, 6...Polyurethane resin-forming composition, 7...Coating film.

Claims

1. (A) A polyol comprising at least one selected from the group consisting of polycarbonate polyols and polyester polyols, (B) Urethane metal catalyst, (C) At least one carbonyl compound selected from the group consisting of carboxylic acids, carboxylic acid anhydrides, and β-diketones, (D) Contains a hindered amine-based light stabilizer, A polyol composition having a volatile organic compound content of 0 to 10% by mass.

2. (E) The polyol composition according to claim 1, further containing an ultraviolet absorber.

3. The polyol composition according to claim 1, wherein the (C) component comprises at least one selected from the group consisting of carboxylic acids and β-diketones.

4. The polyol composition according to claim 1, wherein the content of component (C) is 0.1 to 30.0 mol per 1 mol of component (B).

5. (A) A polyol comprising at least one selected from the group consisting of polycarbonate polyols and polyester polyols, (B) Urethane metal catalyst, (C) At least one carbonyl compound selected from the group consisting of carboxylic acids, carboxylic acid anhydrides, and β-diketones, (D) Hindered amine-based light stabilizers, (F) Contains polyisocyanate, A polyurethane resin-forming composition having a volatile organic compound content of 0 to 10% by mass.

6. The polyurethane resin-forming composition according to claim 5, which is used as a coating agent for in-mold coating.

7. A coating agent set for preparing the polyurethane resin-forming composition described in claim 5, A coating agent set comprising a first agent containing component (A), component (B), component (C), and component (D), and a second agent containing component (F).

8. A coating film comprising a reaction product of the polyurethane resin-forming composition described in claim 5.

9. The process involves preparing a base material and a mold in which the base material is placed inside, The polyurethane resin-forming composition according to claim 5 is injected into the mold, and the polyurethane resin-forming composition is applied to the surface of the substrate, A method for forming a coating film, comprising reacting the polyurethane resin-forming composition to form a coating film on the surface of the substrate.

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