Thermosetting resin sheet, vehicle, vehicle part, and method for manufacturing vehicle and vehicle part

Abstract

The present invention provides a thermosetting resin sheet (1) having at least a top coat layer (10) formed from a first thermosetting resin composition and a resin layer (20) formed from a second thermosetting resin composition, wherein the logarithm of the dynamic loss tangent of the thermosetting resin sheet (1) at 25°C measured using a dynamic viscoelasticity measuring device is 1 or less, the first thermosetting resin composition contains a first polyol resin and a first curing agent, the second thermosetting resin composition contains a second polyol resin and a second curing agent, the ratio of the peak intensity of a second peak of the top coat layer (10) having an absorption maximum in the region of 3520±30 cm-1 in the total reflection infrared absorption spectrum to the peak intensity of a first peak of the top coat layer (10) having an absorption maximum in the region of 2920±20 cm-1 is between 0.15 and 0.60 inclusive, and the ratio of the peak intensity of a third peak of the top coat layer (10) having an absorption maximum in the region of 1460±20 cm-1 to the peak intensity of the second peak is between 6.0 and 20.0 inclusive. A vehicle according to the present invention and a vehicle part according to the present invention are coated using the thermosetting resin sheet (1) according to the present invention. A method for manufacturing a vehicle according to the present invention and a method for manufacturing a vehicle part according to the present invention comprise a step for coating using the thermosetting resin sheet according to the present invention.

Description

Thermosetting resin sheet, vehicle and vehicle part, and method for manufacturing vehicle and vehicle part

[0001] The present invention relates to a thermosetting resin sheet, a vehicle and a vehicle part coated with the thermosetting resin sheet, and a method for manufacturing the vehicle and the vehicle part.

[0002] The exterior of a vehicle or the like is painted with paint. The paint is generally formed by spray-applying a paint for a colored resin layer, then overcoating a paint for a top coat layer, and heating and drying the resulting layer. The top coat layer needs to have a certain degree of hardness to protect the vehicle from external factors, and it is known that increasing the hydroxyl value can increase this hardness (see, for example, Patent Document 1).

[0003] Furthermore, a thermosetting covering sheet, which is attached to the surface of an article such as furniture or a steel plate and thermoset for protecting, decorating, displaying, or the like the surface of the article, and which has an uncured, colored resin layer laminated on a transparent, uncured top coat layer, is known as a prior art (see, for example, Patent Document 2).

[0004] JP2022-78487A JP2022-223445A

[0005] However, in the case of conventional spray coating or conventional thermosetting coating sheets, there are cases where a resin layer such as a colored resin layer and a top coat layer are miscible with each other, resulting in a decrease in the hardness of the top coat layer.

[0006] Therefore, an object of the present invention is to provide a thermosetting resin sheet that can suppress compatibility between a resin layer and a top coat layer and improve the hardness of the top coat layer, a vehicle and vehicle part painted with the thermosetting resin sheet, and a method for manufacturing the vehicle and vehicle part.

[0007] As a result of extensive research, the present inventors have found that the above-mentioned problems can be solved by focusing on the logarithm (log(tan δ)) of the dynamic loss tangent in the dynamic viscoelasticity of a thermosetting resin sheet and the total reflection infrared absorption spectrum of a top coat layer of the thermosetting resin sheet, and have thus completed the present invention. The gist of the present invention is as follows: [1] A thermosetting resin sheet having at least a top coat layer made of a first thermosetting resin composition and a resin layer made of a second thermosetting resin composition, wherein the logarithm (log(tan δ)) of the dynamic loss tangent at 25°C of the thermosetting resin sheet measured by viscoelasticity measurement using a dynamic viscoelasticity measuring apparatus (DMA) is 1 or less, the first thermosetting resin composition includes a first polyol resin and a first curing agent, and the second thermosetting resin composition includes a second polyol resin and a second curing agent, and wherein the logarithm (log(tan δ)) of the dynamic loss tangent at 25°C of the thermosetting resin sheet measured by viscoelasticity measurement using a dynamic mechanical analyzer (DMA) is 1 or less, －１ 3520±30 cm in the total reflection infrared absorption spectrum of the top coat layer relative to the peak intensity (Pt1) of the first peak having an absorption maximum in the region －１ a peak intensity ratio (Pt2 / Pt1) of a peak intensity (Pt2) of a second peak having an absorption maximum in the region of 1460±20 cm in the total reflection infrared absorption spectrum of the top coat layer to a peak intensity (Pt2) of the second peak in the total reflection infrared absorption spectrum of the top coat layer is 0.15 or more and 0.60 or less, －１ [2] A thermosetting resin sheet having a peak intensity ratio (Pt3 / Pt2) of a third peak (Pt3) having an absorption maximum in the region of 2920±20 cm in the total reflection infrared absorption spectrum of the resin layer. －１ 3520±30 cm in the total reflection infrared absorption spectrum of the resin layer relative to the peak intensity (Pc1) of the first peak having an absorption maximum in the region －１The thermosetting resin sheet according to the above [1], wherein the peak intensity ratio (Pc2 / Pc1) of the peak intensity (Pc2) of the second peak having an absorption maximum in the region of 0.05 or more and 0.35 or less. [3] The thermosetting resin sheet according to the above [2], wherein the second thermosetting resin composition further contains a colorant. [4] The thermosetting resin sheet according to any one of the above [1] to [3], wherein the weight-average molecular weights of the first polyol resin and the second polyol resin are each 50,000 or more and 1,000,000 or less. [5] The thermosetting resin sheet according to any one of the above [1] to [4], wherein the first polyol resin and the second polyol resin each contain at least a (meth)acrylic resin having a plurality of hydroxyl groups. [6] The thermosetting resin sheet according to any one of the above [1] to [5], wherein the reaction initiation temperatures of the first curing agent and the second curing agent are both 180°C or less. [7] A vehicle painted using the thermosetting resin sheet described in any one of [1] to [6] above. [8] A vehicle part painted using the thermosetting resin sheet described in any one of [1] to [6] above. [9] A method for manufacturing a vehicle, comprising a step of painting using the thermosetting resin sheet described in any one of [1] to [6] above.

[10] A method for manufacturing a vehicle part, comprising a step of painting using the thermosetting resin sheet described in any one of [1] to [6] above.

[0008] According to the present invention, it is possible to provide a thermosetting resin sheet that can suppress compatibility between a resin layer and a top coat layer and improve the hardness of the top coat layer, as well as a vehicle and a vehicle part painted with the thermosetting resin sheet.

[0009] Fig. 1 is a schematic cross-sectional view showing an example of a thermosetting resin sheet of the present invention. Fig. 2 is a schematic cross-sectional view showing an example of a thermosetting resin sheet of the present invention. Fig. 3 is a schematic cross-sectional view showing an example of a thermosetting resin sheet of the present invention.

[0010] [Thermosetting resin sheet] The thermosetting resin sheet of the present invention has at least a top coat layer made of a first thermosetting resin composition and a resin layer made of a second thermosetting resin composition. The first thermosetting resin composition in the thermosetting resin sheet of the present invention contains a first polyol resin and a first curing agent, and the second thermosetting resin composition in the thermosetting resin sheet of the present invention contains a second polyol resin and a second curing agent. The thermosetting resin sheet of the present invention may consist of only the top coat layer and the resin layer, or may have other layers in addition to the top coat layer and the resin layer.

[0011] (Thermosetting resin composition) The first thermosetting resin composition contains a first polyol resin, and the second thermosetting resin composition contains a second polyol resin. The polyol resin contained in the first thermosetting resin composition may be the same as or different from the polyol resin contained in the second thermosetting resin composition. The first polyol resin and the second polyol resin refer to the polyol resin contained in the first thermosetting resin composition and the polyol resin contained in the second thermosetting resin composition, respectively. Therefore, when the first thermosetting resin composition contains multiple types of polyol resins, the multiple types of polyol resins are collectively referred to as the first polyol resin, and when the second thermosetting resin composition contains multiple types of polyol resins, the multiple types of polyol resins are collectively referred to as the second polyol resin.

[0012] <Polyol Resin> Examples of the first polyol resin and the second polyol resin include (meth)acrylic polyol resin, polycarbonate polyol resin, polyester polyol resin, and epoxy resin-modified polyol resin, and among these, (meth)acrylic polyol resin is preferred.

[0013] The weight average molecular weight of the first polyol resin and the second polyol resin is preferably 50,000 or more and 1,000,000 or less. When the weight average molecular weight of the first polyol resin and the second polyol resin is 50,000 or more and 1,000,000 or less, the coatability, curability, tackiness, extensibility, etc. of the top coat layer and the resin layer are easily balanced and good. From this viewpoint, the weight average molecular weight of the first polyol resin and the second polyol resin is more preferably 60,000 or more and 800,000 or less, even more preferably 70,000 or more and 600,000 or less, and even more preferably 80,000 or more and 600,000 or less. In this specification, the weight average molecular weight is measured by gel permeation chromatography (GPC) and is calculated as a standard polystyrene equivalent value. Furthermore, the weight average molecular weight of the first polyol resin and the second polyol resin may be the same or different.

[0014] The hydroxyl value of the first polyol resin is preferably 50 mgKOH / g or more and 300 mgKOH / g or less. When the hydroxyl value of the first polyol resin is 50 mgKOH / g or more, the hardness of the top coat layer can be further increased. When the hydroxyl value of the first polyol resin is 300 mgKOH / g or less, the adhesive strength of the top coat layer to the resin layer can be further increased. From this viewpoint, the hydroxyl value of the first polyol resin is more preferably 60 mgKOH / g or more and 250 mgKOH / g or less, and even more preferably 70 mgKOH / g or more and 220 mgKOH / g or less. On the other hand, the hydroxyl value of the second polyol resin is preferably 10 mgKOH / g or more and 250 mgKOH / g or less. When the hydroxyl value of the second polyol resin is 10 mgKOH / g or more, the strength of the resin layer can be further increased. When the hydroxyl value of the second polyol resin is 250 mgKOH / g or less, the adhesive strength of the resin layer to the coated plate can be further increased. From this viewpoint, the hydroxyl value of the second polyol resin is more preferably 20 mgKOH / g or more and 200 mgKOH / g or less, and even more preferably 30 mgKOH / g or more and 180 mgKOH / g or less. When the first thermosetting resin composition and the second thermosetting resin composition contain multiple types of polyol resins, the hydroxyl value of the first polyol resin and the hydroxyl value of the second polyol resin are weighted average values ​​of the hydroxyl values ​​of the polyol resins contained in each thermosetting resin composition. For example, when two types of polyol resins, polyol resin (d1) and polyol resin (d2), are used as the polyol resin, the hydroxyl value of polyol resin (d1) is set to X １ , the blending ratio is m １ , the hydroxyl value of the polyol resin (d2) is X ２ , the blending ratio is m ２ Then, the weighted average value of the hydroxyl value is expressed by the following formula. The blending ratio is based on mass. Weighted average value of the hydroxyl value (mgKOH / g) = X １ × (m １ / (m １ +m ２ )) + X ２ × (m ２ / (m １ +m ２)) The hydroxyl value can be measured in accordance with JIS K 1557-1:2007.

[0015] Both the first polyol resin and the second polyol resin preferably contain a (meth)acrylic resin having a plurality of hydroxyl groups. That is, the first polyol resin and the second polyol resin are preferably (meth)acrylic polyol resins. The number of hydroxyl groups in each of the first polyol resin and the second polyol resin is not particularly limited as long as it is two or more. The (meth)acrylic resin may have a functional group other than a hydroxyl group. Examples of functional groups other than a hydroxyl group include an amino group and a carboxyl group.

[0016] The (meth)acrylic resin ((meth)acrylic polyol resin) is an acrylic polymer obtained by polymerizing a monomer mixture preferably containing a (meth)acrylic acid ester monomer and a functional group-containing monomer having a hydroxyl group. Such an alkyl polymer can incorporate hydroxyl groups into the acrylic polymer by the hydroxyl group-containing monomer. Note that (meth)acrylic means methacrylic or acrylic, and the same applies to other similar terms.

[0017] Examples of the (meth)acrylic acid ester monomer include (meth)acrylic acid ester monomers having no functional group, such as alkyl (meth)acrylates having an alkyl group with about 1 to 18 carbon atoms, such as methyl (meth)acrylate and ethyl (meth)acrylate, (meth)acrylates having an aromatic ring, such as benzyl (meth)acrylate and phenoxydiethylene glycol (meth)acrylate, and 2-ethoxyethyl (meth)acrylate.

[0018] The hydroxyl group-containing monomer is not particularly limited, and examples thereof include (meth)acrylic acid ester monomers having a hydroxyl group, such as 2-hydroxyethyl (meth)acrylate.

[0019] The monomer mixture may also contain monomers other than the above-mentioned (meth)acrylic acid ester monomers and hydroxyl group-containing monomers, such as monomers containing functional groups other than hydroxyl groups, and styrene derivative monomers. By using a monomer containing a functional group other than hydroxyl groups, such as an amino group or a carboxyl group, in addition to the hydroxyl group-containing monomer, it is possible to introduce functional groups other than hydroxyl groups into the (meth)acrylic resin in addition to hydroxyl groups. The amino group-containing monomer is not particularly limited, and examples thereof include (meth)acrylic acid ester monomers having an amino group, such as 2-aminoethyl (meth)acrylate. The carboxyl group-containing monomer is not particularly limited, and examples thereof include (meth)acrylic acid. The styrene derivative monomer is not particularly limited, and examples thereof include styrene, α-methylstyrene, α-ethylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-ethoxystyrene, p-chlorostyrene, m-chlorostyrene, and o-chlorostyrene.

[0020] The (meth)acrylic resin may also be a copolymer obtained by block or graft polymerization of the above-mentioned acrylic polymer with another monomer or polymer, such as an acrylic, styrene, maleic acid, imide, silicone, or fluorine-based monomer, or a polymer of such a monomer.

[0021] The content of the first polyol resin in the first thermosetting resin composition and the content of the second polyol resin in the second thermosetting resin composition are each preferably 20% by mass or more and 80% by mass or less, more preferably 30% by mass or more and 70% by mass or less, and even more preferably 35% by mass or more and 60% by mass or less. The content of the first polyol resin in the first thermosetting resin composition may be the same as or different from the content of the second polyol resin in the second thermosetting resin composition. The thermosetting resin composition may be diluted with a volatile component such as a solvent as described below. In this specification, the content (mass%) of each component in the thermosetting resin composition means a value based on the solids content excluding the volatile component.

[0022] As long as the effects of the present invention are not impaired, the first thermosetting resin may contain a thermosetting resin other than the first polyol resin, and the second thermosetting resin may contain a thermosetting resin other than the second polyol resin. Examples of the thermosetting resin other than the first polyol resin and the thermosetting resin other than the second polyol resin include (meth)acrylic resins other than polyol resins, polycarbonate resins other than polyol resins, polyester resins other than polyol resins, and epoxy resins other than polyol resins. These thermosetting resins can be used alone or in combination of two or more.

[0023] <Curing Agent> The first thermosetting resin composition contains a first curing agent, and the second thermosetting resin composition contains a second curing agent.

[0024] The first curing agent and the second curing agent are each preferably a blocked isocyanate curing agent. A blocked isocyanate curing agent is a compound in which an isocyanate group is blocked with a protecting group. When exposed to high temperatures, the protecting group (blocking moiety) thermally dissociates and is removed, causing a curing reaction between the resulting isocyanate group and a functional group in the curable resin (typically, a hydroxyl group in a polyol resin). The blocked isocyanate curing agent can be obtained, for example, by reacting a blocking agent with an isocyanate compound having two or more isocyanate groups per molecule. The isocyanate compound having two or more isocyanate groups per molecule is not particularly limited, and examples thereof include tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, and modified products thereof. Examples of blocking agents include pyrazoles, phenols, oximes, lactams, and malonic acid esters. The blocked isocyanate curing agents may be used alone or in combination. The first curing agent and the second curing agent may be the same or different.

[0025] When the first curing agent and the second curing agent are blocked isocyanate curing agents, the reaction initiation temperatures of the first curing agent and the second curing agent are preferably both 180°C or lower. The reaction initiation temperature is the temperature at which the blocked isocyanate curing agent dissociates to generate an isocyanate group (thermal dissociation temperature). It is preferable that the reaction initiation temperatures of the first curing agent and the second curing agent are both 180°C or lower, since this allows the thermosetting resin sheet to be cured at a relatively low temperature. From the viewpoint of curing the thermosetting resin sheet at a low temperature, the reaction initiation temperatures of the first curing agent and the second curing agent are both more preferably 160°C or lower, and even more preferably 140°C or lower. Furthermore, from the viewpoint of the storage stability of the thermosetting resin sheet, the reaction initiation temperatures of the first curing agent and the second curing agent are both preferably 40°C or higher, and more preferably 60°C or higher. The reaction initiation temperature can be measured by, for example, mixing an equivalent amount of a resin highly reactive with isocyanate, such as a polyol resin, with the blocked isocyanate, stirring at a predetermined temperature for 6 hours, and then evaluating the gel fraction.

[0026] When the first curing agent and the second curing agent are blocked isocyanate curing agents, the content of the first curing agent in the first thermosetting resin composition and the content of the second curing agent in the second thermosetting resin composition are adjusted so that the ratio of the number of functional groups in the thermosetting resin to the number of isocyanate groups in the curing agent is preferably 0.4 or more and 1.8 or less, more preferably 0.6 or more and 1.5 or less.

[0027] When the first curing agent and the second curing agent are blocked isocyanate curing agents, the content of the first curing agent in the first thermosetting resin composition and the content of the second curing agent in the second thermosetting resin composition are not particularly limited as long as they are adjusted so that the ratio of the number of functional groups to the number of isocyanate groups falls within the above-mentioned range, but are each preferably 20% by mass or more and 80% by mass or less, more preferably 30% by mass or more and 70% by mass or less, and even more preferably 40% by mass or more and 60% by mass or less. The content of the first curing agent in the first thermosetting resin composition may be the same as or different from the content of the second curing agent in the second thermosetting resin composition.

[0028] <Plasticizer> The first thermosetting resin composition and the second thermosetting resin composition may contain a plasticizer. In particular, it is preferable that the second thermosetting resin composition contains a plasticizer. The plasticizer is preferably a (meth)acrylic polymer. Examples of (meth)acrylic polymers used as plasticizers include non-functional (meth)acrylic polymers, (meth)acrylic polymers having hydroxyl groups, (meth)acrylic polymers having carboxyl groups, (meth)acrylic polymers having epoxy groups, and (meth)acrylic polymers having alkoxysilyl groups. These (meth)acrylic polymers can be used alone or in combination of two or more. Among these (meth)acrylic polymers, (meth)acrylic polymers having hydroxyl groups are preferred.

[0029] The weight average molecular weight of the (meth)acrylic polymer used as the plasticizer is preferably 200 or more and 8,000 or less, more preferably 300 or more and 6,000 or less, and even more preferably 400 or more and 4,000 or less.

[0030] The glass transition temperature of the (meth)acrylic polymer used as the plasticizer is preferably 10°C or lower, more preferably -80°C or higher and 0°C or lower.

[0031] The hydroxyl value of the (meth)acrylic polymer used as a plasticizer is preferably 20 mgKOH / g or more and 250 mgKOH / g or less, more preferably 40 mgKOH / g or more and 200 mgKOH / g or less, and even more preferably 60 mgKOH / g or more and 150 mgKOH / g or less.

[0032] When the first thermosetting resin composition and the second thermosetting resin composition contain a plasticizer, the content of the plasticizer in the thermosetting resin composition is preferably 1 part by mass or more and 40 parts by mass or less, more preferably 5 parts by mass or more and 30 parts by mass or less, and even more preferably 7 parts by mass or more and 20 parts by mass or less, relative to 100 parts by mass of the total content of the polyol resin, the curing agent, and the plasticizer.

[0033] The plasticizer in the first thermosetting resin composition may be the same as or different from the plasticizer in the second thermosetting resin composition, and the content of the plasticizer in the first thermosetting resin composition may be the same as or different from the content of the plasticizer in the second thermosetting resin composition.

[0034] (Ratio of Curing Agent Content to Total Content of Polyol Resin and Plasticizer) The ratio of the content of the first curing agent to the total content of the first polyol resin and the plasticizer in the first thermosetting resin composition (first curing agent / (first polyol resin + plasticizer)) is preferably 0.3 to 3.0. When the content ratio (first curing agent / (first polyol resin + plasticizer)) is 0.3 to 3.0, it becomes easy to set the peak intensity ratio (Pt3 / Pt2) within the above range. From this viewpoint, the content ratio (first curing agent / (first polyol resin + plasticizer)) is more preferably 0.4 to 2.7, and even more preferably 0.5 to 2.5.

[0035] The ratio of the content of the second curing agent to the total content of the content of the second polyol resin and the content of the plasticizer in the second thermosetting resin composition (second curing agent / (second polyol resin + plasticizer)) is preferably 0.3 to 2.0. When the content ratio (first curing agent / (first polyol resin + plasticizer)) is 0.3 to 2.0, the adhesive strength of the resin layer can be further increased. From this viewpoint, the content ratio (second curing agent / (first polyol resin + plasticizer)) is more preferably 0.4 to 1.8, and even more preferably 0.5 to 1.6.

[0036] <Colorant> The second thermosetting resin composition may further contain a colorant. By including a colorant in the second thermosetting resin composition, the resin layer can be colored, and the resin layer becomes a colored resin layer. This can improve the design of the thermosetting resin sheet. Examples of colorants include pigments, dyes, and luster pigments. Examples of pigments include metal oxide pigments such as titanium oxide and iron oxide, inorganic pigments such as carbon black, clay, kaolin, barium sulfate, barium carbonate, calcium carbonate, talc, silica, and alumina white, and organic pigments such as azo pigments, quinacridone pigments, diketopyrrolopyrrole pigments, perylene pigments, perinone pigments, benzimidazolone pigments, vat pigments, isoindoline pigments, isoindolinone pigments, metal chelate azo pigments, phthalocyanine pigments, indanthrone pigments, dioxane pigments, and indigo pigments. Examples of dyes include azo dyes, anthraquinone dyes, indigoid dyes, stilbene dyes, etc. Examples of glittering materials include compounds in which a titanium oxide layer is provided on the surface of natural mica, synthetic mica, alumina flakes, glass flakes, etc. These colorants can be used alone or in combination of two or more.

[0037] The content of the active components of the colorant in the second thermosetting resin composition, i.e., the content of the colorant excluding the binder resin, dispersant, and additives, varies depending on the colorant color. For example, the content of a white colorant required to impart hiding power to the second thermosetting resin composition is much larger than the content of a black colorant. For example, when the colorant is a black colorant such as carbon black, the content of the colorant is, for example, 0.5 parts by mass or more, preferably 1 part by mass or more, more preferably 2 parts by mass or more, and preferably 25 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 12 parts by mass or less, per 100 parts by mass of the total content of the second polyol resin, the second curing agent, and the plasticizer.

[0038] <Other Components> The first thermosetting resin composition and the second thermosetting resin composition may each contain components other than those described above, for example, additives other than those described above. Examples of the additives include a surface conditioner, an antifoaming agent, a urethanization catalyst, a crosslinking agent, a dispersant, an inorganic filler other than a pigment and a luster material, an antioxidant, an antioxidant, and a rust inhibitor.

[0039] The first thermosetting resin composition may contain a colorant in addition to the first polyol resin and the first curing agent, but it is sufficient if the first thermosetting resin composition does not contain a colorant, or if it does contain a colorant, it is sufficient that the amount is such that transparency is not impaired, and the top coat layer is preferably a so-called clear layer. Note that the clear layer is a transparent layer, and transparency means that the transmittance of light with a wavelength of 450 nm is 80% or more. On the other hand, if the second thermosetting resin composition contains a colorant, the resin layer is a colored resin layer, and the colored resin layer is preferably an opaque layer.

[0040] (Hydroxyl value) The hydroxyl value of the top coat layer is preferably 50 mgKOH / g or more and 300 mgKOH / g or less. When the hydroxyl value of the top coat layer is 50 mgKOH / g or more, the hardness of the top coat layer can be further increased. When the hydroxyl value of the top coat layer is 300 mgKOH / g or less, the adhesive strength of the top coat layer to the resin layer can be further increased. From this viewpoint, the hydroxyl value of the top coat layer is more preferably 60 mgKOH / g or more and 250 mgKOH / g or less, and even more preferably 70 mgKOH / g or more and 220 mgKOH / g or less.

[0041] The hydroxyl value of the resin layer is preferably 20 mgKOH / g or more and 140 mgKOH / g or less. When the hydroxyl value of the resin layer is 20 mgKOH / g or more, the strength of the resin layer can be further increased. When the hydroxyl value of the resin layer is 140 mgKOH / g or less, the adhesion strength of the resin layer to the coated plate can be further increased. From this viewpoint, the hydroxyl value of the resin layer is more preferably 40 mgKOH / g or more and 120 mgKOH / g or less, and even more preferably 60 mgKOH / g or more and 110 mgKOH / g or less. The hydroxyl value of the top coat layer is a weighted average value of the hydroxyl values ​​of the first polyol resin and the plasticizer contained in the first thermosetting resin composition. On the other hand, the hydroxyl value of the resin layer is a weighted average value of the hydroxyl values ​​of the second polyol resin and the plasticizer contained in the second thermosetting resin composition.

[0042] (Logarithm of Dynamic Loss Tangent (log(tan δ))) The logarithm of the dynamic loss tangent (log(tan δ)) of the thermosetting resin sheet of the present invention at 25°C, measured by viscoelasticity measurement using a dynamic viscoelasticity measuring apparatus (DMA), is 1 or less. If the log(tan δ) of the thermosetting resin sheet at 25°C is greater than 1, the top coat layer may become compatible with the resin layer, resulting in a problem of reduced hardness of the top coat layer. In addition, it may become difficult for the thermosetting resin sheet to properly maintain its sheet shape, resulting in a poor appearance. From these viewpoints, the log(tan δ) of the thermosetting resin sheet of the present invention at 25°C, measured by viscoelasticity measurement using a DMA, is preferably 0.5 or less, more preferably 0.2 or less, and even more preferably 0.15 or less. The lower limit of the range of log (tan δ) at 25 ° C. of the thermosetting resin sheet of the present invention measured by viscoelasticity measurement using DMA is not particularly limited, but is usually 0.05, preferably 0.1 or more, more preferably 0.12 or more. The log (tan δ) at 25 ° C. of the thermosetting resin sheet measured by viscoelasticity measurement using DMA can be measured by the method described in the Examples below. The log (tan δ) at 25 ° C. of the thermosetting resin sheet measured by viscoelasticity measurement using DMA can be adjusted by the hydroxyl value of the first polyol resin, the hydroxyl value of the second polyol resin, the weight average molecular weight of the first polyol resin, the weight average molecular weight of the second polyol resin, etc. The larger the hydroxyl value of the first polyol resin, the hydroxyl value of the second polyol resin, the weight average molecular weight of the first polyol resin, and the weight average molecular weight of the second polyol resin, the smaller the log(tan δ) value of the thermosetting resin sheet.

[0043] (Total Reflection Infrared Absorption Spectrum) The peak intensity ratio (Pt2 / Pt1) of the thermosetting resin sheet of the present invention is 0.15 or more and 0.60 or less. Pt1 is the peak intensity ratio of 2920±20 cm in the total reflection infrared absorption spectrum of the top coat layer. －１The first peak is the peak intensity of the first peak having an absorption maximum in the region of 3520±30 cm in the total reflection infrared absorption spectrum of the top coat layer. －１ The peak intensity ratio (Pt2 / Pt1) is the peak intensity of a second peak having an absorption maximum in the region of 2920±20 cm. The second peak is a hydroxyl group peak. If the peak intensity ratio (Pt2 / Pt1) is less than 0.15, the amount of hydroxyl groups in the top coat layer may be insufficient, resulting in a low hardness of the top coat layer. If the peak intensity ratio is greater than 0.60, the amount of hydroxyl groups may be too large, resulting in problems such as peeling of the top coat layer from other resin layers, such as the resin layer. From this perspective, the peak intensity ratio (Pt2 / Pt1) of the thermosetting resin sheet of the present invention is preferably 0.18 or more and 0.55 or less, more preferably 0.2 or more and 0.50 or less, and even more preferably 0.22 or more and 0.45 or less. In addition, the peak intensity ratio (Pt2 / Pt1) at 2920±20 cm in the total reflection infrared absorption spectrum of the top coat layer is －１ and the peak intensity of the first peak having an absorption maximum in the region of 3520±30 cm in the total reflection infrared absorption spectrum of the top coat layer. －１ The peak intensity of the second peak having an absorption maximum in the region can be measured by the method described in the Examples below. The peak intensity ratio (Pt2 / Pt1) can be adjusted by the hydroxyl value of the first polyol resin and the content of the first polyol resin. Note that the above peak intensity is the peak intensity of the thermosetting resin sheet before thermal curing.

[0044] The thermosetting resin sheet of the present invention has a peak intensity ratio (Pt3 / Pt2) of 6.0 or more and 20.0 or less. Pt3 is a peak intensity ratio of 1460±20 cm in the total reflection infrared absorption spectrum of the top coat layer. －１The peak intensity ratio (Pt3 / Pt2) is the peak intensity of a third peak having an absorption maximum in the region of 3520±30 cm in the total reflection infrared absorption spectrum of the top coat layer. Furthermore, the third peak is a peak derived from blocked isocyanate. If the peak intensity ratio (Pt3 / Pt2) is less than 6.0 or more than 20.0, the balance between the amounts of polyol resin and curing agent in the top coat layer is poor, and problems such as a low hardness of the top coat layer are likely to occur. From this viewpoint, the peak intensity ratio (Pt3 / Pt2) of the thermosetting resin sheet of the present invention is preferably 7.0 or more and 18.0 or less, more preferably 7.5 or more and 17.0 or less, and even more preferably 8.0 or more and 14.0 or less. Furthermore, the peak intensity ratio (Pt3 / Pt2) of the top coat layer at 3520±30 cm in the total reflection infrared absorption spectrum of the top coat layer is －１ and the peak intensity of the second peak having an absorption maximum in the region of 1460±20 cm in the total reflection infrared absorption spectrum of the top coat layer. －１ The peak intensity of the third peak having an absorption maximum in the region of Pt3 can be measured by the method described in the Examples below. The peak intensity ratio (Pt3 / Pt2) can be adjusted by the hydroxyl value of the first polyol resin, the content of the first polyol resin, the number of isocyanate groups in the first curing agent, the content of the first curing agent, etc.

[0045] The peak intensity ratio (Pc2 / Pc1) in the thermosetting resin sheet of the present invention is preferably 0.05 or more and 0.35 or less. Pc1 is the peak intensity ratio at 2920±20 cm in the total reflection infrared absorption spectrum of the resin layer. －１ Pc2 is the peak intensity of the first peak having an absorption maximum in the region of 3520±30 cm in the total reflection infrared absorption spectrum of the resin layer. －１The peak intensity ratio (Pc2 / Pc1) is the peak intensity of the second peak having an absorption maximum in the region of 2920±20 cm in the total reflection infrared absorption spectrum of the resin layer. When the peak intensity ratio (Pc2 / Pc1) is 0.05 or more and 0.35 or less, the strength of the resin layer is likely to be high, and the adhesive strength of the resin layer is also likely to be high. From this viewpoint, the peak intensity ratio (Pc2 / Pc1) of the thermosetting resin sheet of the present invention is preferably 0.06 or more and 0.60 or less, more preferably 0.07 or more and 0.40 or less, and even more preferably 0.08 or more and 0.18 or less. In addition, the peak intensity ratio (Pc2 / Pc1) of the thermosetting resin sheet of the present invention is preferably 0.06 or more and 0.60 or less, more preferably 0.07 or more and 0.40 or less, and even more preferably 0.08 or more and 0.18 or less. In the total reflection infrared absorption spectrum of the resin layer, the peak intensity ratio (Pc2 / Pc1) of the resin layer is 2920±20 cm －１ and the peak intensity of the first peak having an absorption maximum in the region of 3520±30 cm in the total reflection infrared absorption spectrum of the resin layer. －１ The peak intensity of the second peak having an absorption maximum in the region of (A) can be measured by the method described in the Examples below. The peak intensity ratio (Pc2 / Pc1) can be adjusted by the hydroxyl value of the second polyol resin, the content of the second polyol resin, the content of the plasticizer, and the hydroxyl value of the plasticizer.

[0046] (Thickness) The thickness of the top coat layer is not particularly limited, but is, for example, 10 μm to 100 μm, preferably 15 μm to 50 μm. The thickness of the resin layer is also not particularly limited, but is, for example, 10 μm to 100 μm, preferably 15 μm to 50 μm.

[0047] (Layer Structure of Thermosetting Resin Sheet) As shown in FIG. 1, the thermosetting resin sheet 1 may consist only of a top coat layer 10 and a resin layer 20. Alternatively, another resin layer may be provided between the top coat layer and the resin layer. For example, as shown in FIG. 2, the thermosetting resin sheet 1A may include a top coat layer 10, a resin layer 20, and another resin layer 30 provided between the top coat layer 10 and the resin layer 20. When another resin layer is provided, the other resin layer may be made of the same material as the top coat layer and the resin layer. The other resin layer preferably contains, for example, a polyol resin and a curing agent. In this embodiment, even if another resin layer is provided between the top coat layer and the resin layer, the peel strength between the resin layers can be increased and interfacial peeling between the resin layers can be prevented. The other resin layer may contain a colorant in addition to the polyol resin and the curing agent. The design of the thermosetting resin sheet can be further improved by combining a resin layer containing a colorant and another resin layer containing a colorant. The other resin layer may include two or more layers.

[0048] (Transfer Layer) The thermosetting resin sheet of the present invention may further include a transfer layer provided on the side opposite the resin layer side of the top coat layer. For example, as shown in FIG. 3, the thermosetting resin sheet 1B may further include a transfer layer 40 provided on the side opposite the resin layer side of the top coat layer 10. The transfer layer used in the thermosetting resin sheet is a member that protects the top coat layer from scratches and foreign matter adhesion. As will be described later, it also serves as a support when attaching the top coat layer and resin layer to an adherend, and typically serves as a support when transferring the top coat layer and resin layer of the thermosetting resin sheet to an adherend. The transfer layer is preferably formed from a resin film. Examples of resins used in the resin film include thermoplastic resins. Specific examples of resins used in the resin film include cyclic polyolefin resins, polyolefin resins, polyester resins such as polybutylene terephthalate and polyethylene terephthalate, polyamide resins, polycarbonate resins, acrylic resins, fluororesins, soft vinyl chloride resins, polymethylpentene resins, and tetrafluoroethylene resins. Among these, cyclic polyolefin resins or polyolefin resins are preferred.

[0049] Cyclic polyolefin resins are polymers containing structural units derived from cyclic olefins. Examples of cyclic olefins include tetracyclododecene, norbornene, and cyclic conjugated dienes. The cyclic polyolefin resin may be a polymer of a cyclic olefin, a copolymer of a cyclic olefin and an α-olefin, or a hydrogenated product thereof. Examples of the α-olefin include linear α-olefins having 1 to 12 carbon atoms, such as ethylene, propylene, butene-1, pentene-1, hexene-1, heptene-1, and octene-1. Of these, ethylene is preferred.

[0050] The polyolefin resin is a polyolefin resin other than a cyclic polyolefin resin, and specific examples thereof include polypropylene resin and polyethylene resin. Among these, polyethylene resin is preferred. The polypropylene resin may be homopropylene or a copolymer of propylene, such as random polypropylene, with a small amount (for example, 10% by mass or less) of another α-olefin. Examples of the other α-olefin include linear α-olefins having 1 to 12 carbon atoms, such as ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-nonene, and 1-decene. Examples of the polyethylene resin include low-density polyethylene (LDPE, density: 0.930 g / cm ３ less than 0.930 g / cm), medium density polyethylene (MDPE, density: 0.930 g / cm ３ 0.942g / cm or more ３ less than 0.942 g / cm), high density polyethylene (HDPE, density: 0.942 g / cm ３ and linear low density polyethylene (LLDPE).

[0051] The resin film may be a single-layer film consisting of one single layer, or may be a multilayer film consisting of two or more layers. Furthermore, in the resin film constituting the release layer, the resin contained in the resin film may be used alone, or two or more types may be used in combination. When two or more types of resins are used in combination, different types of resins may be used in each layer to form a multilayer film. Furthermore, a single-layer film may be formed by mixing two or more types of resins, or one or more layers in a multilayer film may be formed. Examples of multilayer films include multilayer films in which a layer composed of a cyclic polyolefin resin or a polyolefin resin and a layer composed of a polyester resin are laminated, and examples thereof include multilayer films in which a polyester resin layer, a polyolefin resin layer, and a polyester resin layer are laminated in this order.

[0052] Each layer in the transfer layer may contain additives other than the resin. Known additives that are incorporated into resin films may be used as the additives. Specific additives include nucleating agents, fluorescent whitening agents, antioxidants, stabilizers, UV absorbers, surfactants, lubricants, fillers, crosslinking agents, crosslinking accelerators, antistatic agents, flame retardants, dispersants, pigments, dyes, and processing aids.

[0053] The resin film may be a stretched resin film or a non-stretched resin film, but a non-stretched resin film is preferred. Therefore, the resin film is preferably a non-stretched cyclic polyolefin resin film or a non-stretched polyolefin resin film. By using a non-stretched resin film, it becomes easier to adjust the tensile breaking elongation to the desired range as described above, and it becomes easier to prevent breakage, wrinkles, etc. during vacuum molding. Furthermore, the non-stretched resin film may be a multilayer film, for example, a multilayer film having a polyester resin layer in addition to a polyolefin resin layer as described above.

[0054] The transfer layer may have at least one surface that has been release-treated with a release agent such as a silicone-based release agent or a fluorine-based release agent. When the transfer layer is release-treated, it is preferable that the release-treated surface constitutes the surface on the top coat layer side. The release treatment of the transfer layer makes it easier to peel it from the top coat layer. However, the transfer layer does not need to be release-treated as long as it can be peeled from the top coat layer. The thickness of the transfer layer is not particularly limited, but is, for example, 10 μm or more and 1000 μm or less, preferably 30 μm or more and 600 μm or less, and more preferably 50 μm or more and 400 μm or less.

[0055] (Substrate) The thermosetting resin sheet of the present invention may further include a substrate provided on the side of the resin layer opposite the top coat layer side. For example, as shown in FIG. 3, the thermosetting resin sheet 1B may further include a substrate 50 provided on the side of the resin layer 20 opposite the top coat layer side. The substrate used in the thermosetting resin sheet is a member that protects the resin layer from scratches and foreign matter adhesion. The substrate is preferably formed from a resin film. Examples of resins used in the resin film include thermoplastic resins. Specific examples of thermoplastic resins used in the substrate are the same as those that can be used in the release layer, but polyester resins are preferred.

[0056] The resin film may be a single-layer film consisting of one single layer, or may be a multilayer film consisting of two or more layers. Furthermore, in the resin film constituting the release layer, the resin contained in the resin film may be used alone, or two or more types may be used in combination. When two or more types of resins are used in combination, different types of resins may be used in each layer to form a multilayer film. Furthermore, a single-layer film may be formed by mixing two or more types of resins, or one or more layers in a multilayer film may be formed. Each layer in the substrate may contain additives in addition to the resin. Specific examples of additives are as described in the transfer layer.

[0057] The resin film in the substrate may be a stretched resin film or a non-stretched resin film, but a non-stretched resin film is preferred. Therefore, a non-stretched polyester resin film is preferred as the resin film. By using a non-stretched resin film, it becomes easier to adjust the tensile breaking elongation to the desired range as described above, and it is possible to prevent breakage, wrinkles, etc. during vacuum molding.

[0058] The substrate may have at least one surface that has been release-treated with a release agent such as a silicone-based release agent or a fluorine-based release agent. When the substrate is release-treated, it is preferable that the release-treated surface constitutes the surface on the resin layer side. The release treatment of the substrate makes it easier to releasably release from the resin layer. However, the substrate does not need to be release-treated as long as it can be releasably released from the resin layer. The thickness of the substrate is not particularly limited, but is, for example, 10 μm or more and 1000 μm or less, preferably 30 μm or more and 700 μm or less, and more preferably 50 μm or more and 500 μm or less. In addition, when a layer other than the top coat layer, resin layer, or resin layer disposed between them, such as the transfer layer and substrate, is provided, the viscoelasticity measurement and the reflection infrared absorption spectrum measurement are performed after removing the transfer layer and substrate.

[0059] [Method for Producing Thermosetting Resin Sheet] The method for producing a thermosetting resin sheet of the present invention includes the following steps A, B, and C. (1) Step A In step A, a first coating material containing a first thermosetting resin composition containing a first polyol resin and a first curing agent is applied to a transfer layer and dried to produce a first laminate including a transfer layer and a top coat layer formed on the transfer layer and made of the first thermosetting resin composition. Note that the first thermosetting resin composition, the transfer layer, and the top coat layer are described above in the section "Thermosetting Resin Sheet," so description of the first thermosetting resin composition, the transfer layer, and the top coat layer will be omitted.

[0060] The first coating material may be made of the first thermosetting resin composition, but from the viewpoint of improving workability such as coating properties, it is preferable that the first thermosetting resin composition be diluted with a solvent, such as ethyl acetate, butyl acetate, or toluene.

[0061] Furthermore, the drying carried out after applying the first coating material to the transfer layer is preferably drying that includes at least the main drying step described below, and more preferably drying that involves the pre-drying step and the main drying step described below in this order.

[0062] The drying temperature in the pre-drying step is preferably 50°C or higher and 70°C or lower, more preferably 55°C or higher and 65°C or lower. The drying time in the pre-drying step is preferably 1 minute or higher and 30 minutes or lower, more preferably 2 minutes or higher and 15 minutes or lower. The drying temperature in the main drying step is preferably 85°C or higher and 130°C or lower, more preferably 90°C or higher and 120°C or lower. When the drying temperature is above these lower limits, the solvent is easily removed properly, preventing the evaporation of the solvent and the generation of bubbles when curing the resin layer. Furthermore, by setting the drying temperature below the above upper limit, the thermosetting resin composition can be prevented from curing more than necessary during drying. The drying time in the main drying step is preferably 1 minute or higher and 30 minutes or lower, more preferably 2 minutes or higher and 15 minutes or lower. Setting the drying time above the above lower limit makes it easy to remove the solvent properly, preventing the evaporation of the solvent and the generation of bubbles when curing the resin layer. Furthermore, by setting the drying temperature below the above upper limit, the thermosetting resin composition can be prevented from curing more than necessary during drying.

[0063] The dried resin layer may be subjected to initial curing as needed. Initial curing refers to curing the thermosetting resin composition constituting the resin layer to a semi-cured state. Initial curing can be performed by heating, and is preferably performed under conditions of a heating temperature of 90°C or higher and 150°C or lower for a heating time of approximately 2 minutes or higher and 5 minutes or lower.

[0064] (2) Step B In step B, a second coating material containing a second thermosetting resin composition containing a second polyol resin and a second curing agent is applied to a substrate and dried to produce a second laminate comprising the substrate and a resin layer formed on the substrate and made of the second thermosetting resin composition. Note that the second thermosetting resin composition, substrate, and resin layer are explained in the above section "Thermosetting Resin Sheet," so explanation of the second thermosetting resin composition, substrate, and resin layer is omitted here.

[0065] The second coating material may be made of the second thermosetting resin composition, but from the viewpoint of improving workability such as coating properties, it is preferable that the second coating material is made by diluting the second thermosetting resin composition with a solvent, such as ethyl acetate, butyl acetate, or toluene.

[0066] Furthermore, the drying carried out after applying the second coating material to the transfer layer is preferably drying that includes at least the main drying step described below, similar to the drying carried out after applying the first coating material to the transfer layer, and more preferably drying that carries out the pre-drying step and main drying step described below in this order. Note that the pre-drying step and main drying step have been explained in the section "Step A," so explanation of the pre-drying step and main drying step will be omitted.

[0067] (3) Step C In step C, the first laminate and the second laminate are bonded together so that the top coat layer and the resin layer face each other. As a result, a thermosetting resin sheet having a laminated structure of transfer layer / top coat layer / resin layer / substrate can be produced. By producing a decorative thermosetting sheet by bonding the first laminate and the second laminate in this way, it is possible to prevent the top coat layer and the resin layer from becoming miscible, and a high-quality two-layer structure consisting of the top coat layer and the resin layer can be obtained. Furthermore, by peeling the transfer layer and the substrate from this thermosetting resin sheet, a thermosetting resin sheet consisting of the top coat layer and the resin layer can be produced.

[0068] Furthermore, as described above, when another resin layer is provided between the top coat layer and the resin layer, the other resin layer is first formed on a separately provided release film or the like to produce a third laminate. Then, the third laminate is bonded to the first laminate to form the other resin layer on the top coat layer of the first laminate, or the third laminate is bonded to the second laminate to form the other resin layer on the resin layer of the second laminate. Thereafter, as in step C described above, the first and second laminates are bonded together to produce a thermosetting resin sheet comprising a top coat layer, a resin layer, and another resin layer provided between the top coat layer and the resin layer. In this case, the release film may be peeled off after or before laminating the other resin layer to the second or first resin layer. As the release film, a release polyethylene terephthalate film (release PET film) or the like may be used.

[0069] The thermosetting resin sheet of the present invention can also be produced by a method other than the above-described method for producing a thermosetting resin sheet.

[0070] [Method of Use of Thermosetting Resin Sheet] The thermosetting resin sheet of the present invention is a sheet for forming a decorative body, such as a coating, on various articles (adherends), and is used by being attached to the adherend. Specifically, after peeling off the substrate, the thermosetting resin sheet is attached to the adherend via the resin layer, and the thermosetting resin sheet attached to the adherend is heated. The method for peeling off the substrate is not particularly limited, and peeling may be performed using a peeling device or manually. The attachment of the thermosetting resin sheet to the adherend is not particularly limited, and may be performed by hand using a squeegee or the like, or using a laminating device. Furthermore, heating the thermosetting resin sheet hardens the top coat layer and resin layer, and the hardened top coat layer and resin layer form a decorative body.

[0071] The transfer layer is peeled off and removed after the substrate is peeled off. Typically, after the transfer layer is peeled off, the thermosetting resin sheet is heated as described above to cure the top coat layer and resin layer. The transfer layer is preferably peeled off from the top coat layer after the thermosetting resin sheet is bonded to the adherend via the resin layer. This allows the transfer layer to serve as a support for the top coat layer and resin layer when the thermosetting resin sheet is bonded to the adherend. The method for peeling the transfer layer is not particularly limited, and it may be peeled off using a peeling device or manually. The transfer layer may be peeled off at room temperature or a temperature thereabout (approximately 15 to 35°C), or it may be peeled off after the top coat layer has cooled.

[0072] The thermosetting resin sheet of the present invention may be preformed by vacuum forming, press forming, pressure forming, or the like to a shape corresponding to the shape of the adherend, and then laminated to the adherend. Preforming may be performed before peeling the substrate from the resin layer of the thermosetting resin sheet, or after peeling the substrate from the resin layer. Preforming allows the thermosetting resin sheet to be easily adhered to the adherend, even if the adherend has a complex shape. Among the above methods, preforming is preferably performed by vacuum forming. Preforming may be performed by vacuum forming a thermosetting resin sheet pressed against a jig or mold, and stretching the thermosetting resin sheet using the jig or mold to form a shape corresponding to the surface shape of the adherend. Here, the vacuum forming is preferably TOM molding. TOM stands for "Three Dimension Overlay Method," and applying TOM molding allows for forming into complex shapes.

[0073] The adherend to which the thermosetting resin sheet of the present invention can be attached is not particularly limited, but examples thereof include electrical appliances, vehicles such as automobiles and transportation equipment, vehicle parts for vehicles such as automobiles and transportation equipment, exterior materials for miscellaneous goods, heavy machinery, ships, and aircraft, exterior wall or roof materials for houses and buildings, bridges, steel frames, plants, wind power generation blades, etc. Vehicle parts include, for example, vehicle interior materials and vehicle exterior materials. Among these, vehicles and vehicle parts are preferred, vehicle parts are more preferred, and vehicle exterior materials are even more preferred. Examples of vehicle exterior materials include hoods, roofs, door panels, bumpers, fuel filler panels, trunk lids, and rear gates. When attached to vehicle exterior materials, the thermosetting resin sheet of the present invention may be attached to an exterior material attached to the vehicle body, or may be attached to an exterior material before being attached to the vehicle body. The material of the adherend is also not particularly limited, but may be any of resin materials, inorganic materials such as ceramics, and metal materials such as steel, with metal materials such as steel being preferred. Metallic materials such as steel are difficult to paint at the same time as molding the adherend using insert molding, and painting with a resin sheet is difficult, but by using the thermosetting resin sheet of the present invention, such materials can be easily painted.

[0074] [Vehicle, vehicle part, vehicle manufacturing method, vehicle part manufacturing method] The vehicle and vehicle part of the present invention are painted using the thermosetting resin sheet of the present invention. Therefore, the vehicle manufacturing method and vehicle part manufacturing method of the present invention include a step of painting using the thermosetting resin sheet of the present invention. Note that the painting step may be performed by the method described above for forming the paint.

[0075] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples in any way.

[0076] The measurement and evaluation methods in this example are as follows. (Total Reflection Infrared Absorption Spectrum) The total reflection infrared absorption spectrum of each surface of the top coat layer and the resin layer of the thermosetting resin sheet was measured by the ATR (attenuated total reflection) method using an infrared absorption spectrometer FT / IR Nicolet iS5 (manufactured by Yamato Scientific Co., Ltd.) and a diamond prism (iD7). The measurement range was 4000 to 400 cm. －１ , 32 integrations, resolution 4cm －１ It was decided.

[0077] (Dynamic loss tangent (tan δ)) The dynamic loss tangent (tan δ) at 25° C. was measured by viscoelasticity measurement using a dynamic viscoelasticity measuring device ("DVA-200" manufactured by IT Measurement Control Co., Ltd.) in shear mode under conditions of a frequency of 10 Hz and a strain of 0.02%.

[0078] (Coating film hardness after baking) After peeling off the substrate from the thermosetting resin sheet obtained in each Example and Comparative Example, the sheet was bonded to a steel plate via the resin layer, and then the transfer layer was peeled off. The resin layer (top coat layer and resin layer) bonded to the steel plate was cured by heating at 140°C for 30 minutes. The pencil hardness of the surface of the obtained cured product was measured in accordance with JIS K 5600-5-4 and evaluated according to the following evaluation criteria. <Evaluation criteria> A: No scratches were observed at a pencil hardness of HB. B: Scratches were observed at a pencil hardness of HB, but no scratches were observed at a pencil hardness of B. C: Scratches were observed at a pencil hardness of B.

[0079] (Appearance after baking) After peeling off the substrate from the decorative thermosetting resin sheet obtained in each Example and Comparative Example, the sheet was attached to a steel plate via the second resin layer, and then the transfer layer was peeled off. The resin layers (first resin layer and second resin layer) attached to the steel plate were cured by heating at 140°C for 30 minutes. The appearance of the resulting cured product was evaluated according to the following evaluation criteria. <Evaluation criteria> A: The color layer and clear layer were not mixed, and the two-layer structure was visible. B: The color layer and clear layer were mixed, and the two-layer structure was not visible.

[0080] (Adhesion to Substrate) Strip-shaped test specimens measuring 150 mm in length and 25 mm in width were prepared for the decorative thermosetting resin sheets obtained in each Example and Comparative Example. After peeling the substrate, the test specimen was attached to a urethane-coated board test piece via the second resin layer, and then the transfer layer was peeled off. Single-sided tape was attached to the first resin layer, and the single-sided tape, first resin layer, and second resin layer were peeled off simultaneously in accordance with the 90-degree peel test method of JIS Z0237. The peel strength was evaluated according to the following criteria. <Evaluation Criteria> A: Peel strength of 0.5 N / 25 mm or more. B: Peel strength of 0.3 N / 25 mm or more but less than 0.5 N / 25 mm. C: Peel strength of less than 0.3 N / 25 mm.

[0081] The components of the film for transfer layer, the film for base material, and the resin layer used in the examples and comparative examples are as follows: <Film for transfer layer> Unstretched cyclic polyolefin film ("Decofit Q17CK" manufactured by Toray Industries, Inc., thickness 100 μm), tensile elongation at break at 100° C. (MD=1850%, TD=1850%)

[0082] <Film for base layer> Unstretched polyethylene terephthalate film (A-PET) ("A-PET" manufactured by Nakamoto Pax Co., Ltd., thickness 200 μm), tensile elongation at break at 100° C. (MD=1200%, TD=980%)

[0083] <Polyol Resins> Acrylic polyol resin (1): weight average molecular weight 240,000, hydroxyl value 40 mgKOH / g, solid content concentration (NV) = 30 mass% (solvent: ethyl acetate) Acrylic polyol resin (2): weight average molecular weight 250,000, hydroxyl value 80 mgKOH / g, solid content concentration (NV) = 30 mass% (solvent: ethyl acetate) Acrylic polyol resin (3): weight average molecular weight 250,000, hydroxyl value 110 mgKOH / g, solid content concentration (NV) = 30 mass% (solvent: ethyl acetate) Acrylic polyol resin (4): weight average molecular weight 320,000, hydroxyl value 170 mgKOH / g, solid content concentration (NV) = 30 mass% (solvent: ethyl acetate) Acrylic polyol resin (5): weight average molecular weight 250,000, hydroxyl value 200 mgKOH / g, solid content concentration (NV) = 30 mass% (solvent: ethyl acetate)

[0084] <Plasticizer> (meth)acrylic polymer having a hydroxyl group, weight average molecular weight 2500, manufactured by Toagosei Co., Ltd. ("ARUFON UH-2041"), hydroxyl value 120 mg KOH / mg, solid content (NV) = 100% by mass, glass transition temperature -50°C

[0085] <Pigment (colorant)> "NSP-UP 841B" manufactured by Nihon Bix Co., Ltd., effective pigment concentration = 9 mass%, solid content (NV) = 24 mass%

[0086] <Catalyst> Dibutyltin dilaurate (DBTDL), solid content (NV) = 100% by mass

[0087] <Curing agent> Hexamethylene diisocyanate-based blocked isocyanate (HDI-based), blocking agent type: 3,5-dimethylpyrazole (DMP), solid content (NV) = 70%, solvent: ethyl acetate, reaction initiation temperature = 120°C

[0088] [Preparation of Thermosetting Resin Compositions A to Q] Each component was added in the proportions shown in Table 1, and ethyl acetate was added as a solvent to prepare coating materials of thermosetting resin compositions A to Q so that the solid content concentration was 30 mass %.

[0089] Example 1: Thermosetting resin composition A was applied to the surface of a film for a transfer layer using an applicator, followed by a pre-drying process at a drying temperature of 60°C for 30 minutes, followed by a main drying process at a drying temperature of 90°C for 5 minutes, forming a first resin layer with a thickness of 30 μm on the transfer layer. Next, thermosetting resin composition G was applied to the surface of a film for a substrate using an applicator, followed by a pre-drying process at a drying temperature of 60°C for 30 minutes, followed by a main drying process at a drying temperature of 90°C for 5 minutes, forming a second resin layer with a thickness of 30 μm on the substrate. The topcoat layer on the transfer layer and the resin layer on the substrate were bonded together and laminated at 25°C to obtain a laminate in which the transfer layer, topcoat layer, resin layer, and substrate were laminated in this order. The obtained laminate was used for the above evaluations. The evaluation results are shown in Table 2.

[0090] Examples 2 to 12 and Comparative Examples 1 to 4 The same procedures as in Example 1 were carried out, except that the formulation of the thermosetting resin composition was changed as shown in Table 1. The evaluation results are shown in Table 2.

[0091] *Table 1 shows the amount of each component in thermosetting resin compositions A to K based on solid content, with the total solid content of the acrylic polyol resin, plasticizer, and curing agent being 100 parts by mass. *The amount of active ingredient in the pigment is the value in Table 1 multiplied by 9 / 24. *The hydroxyl value of the resin layer is the weighted average of the hydroxyl value of the acrylic polyol resin and the hydroxyl value of the plasticizer.

[0092]

[0093] By comparing Examples 1 to 12 and Comparative Examples 1 to 4, it was found that the hardness of the top coat layer can be improved by setting log(tan δ) to 1 or less, setting the peak intensity ratio (Pt2 / Pt1) to 0.15 or more and 0.60 or less, and setting the peak intensity ratio (Pt3 / Pt2) to 6.0 or more and 20.0 or less.

[0094] REFERENCE SIGNS LIST 1, 1A, 1B Thermosetting resin sheet 10 Top coat layer 20 Resin layer 30 Other resin layer 40 Transfer layer 50 Substrate

Claims

1. A thermosetting resin sheet having at least a top coat layer made of a first thermosetting resin composition and a resin layer made of a second thermosetting resin composition, wherein the logarithm of the dynamic loss tangent (log(tan δ)) of the thermosetting resin sheet at 25°C measured by viscoelasticity measurement using a dynamic viscoelasticity measuring device (DMA) is 1 or less, the first thermosetting resin composition contains a first polyol resin and a first curing agent, the second thermosetting resin composition contains a second polyol resin and a second curing agent, and the peak intensity ratio (Pt2 / Pt1) of the peak intensity (Pt2) of a second peak having an absorption maximum in the region of 3520 ± 30 cm －１ in the total reflection infrared absorption spectrum of the top coat layer to the peak intensity (Pt1) of a first peak having an absorption maximum in the region of 2920 ± 20 cm －１ in the total reflection infrared absorption spectrum of the top coat layer is 0.15 or more and 0.60 or less, and the peak intensity ratio (Pt3 / Pt2) of the peak intensity (Pt3) of a third peak having an absorption maximum in the region of 1460 ± 20 cm －１ in the total reflection infrared absorption spectrum of the top coat layer to the peak intensity (Pt2) of the second peak in the total reflection infrared absorption spectrum of the top coat layer is 6.0 or more and 20.0 or less.

2. The peak intensity ratio (Pc2 / Pc1) of the peak intensity (Pc2) of the second peak having an absorption maximum in the region of 3520 ± 30 cm －１ in the total reflection infrared absorption spectrum of the resin layer to the peak intensity (Pc1) of the first peak having an absorption maximum in the region of 2920 ± 20 cm －１ in the total reflection infrared absorption spectrum of the resin layer is 0.05 or more and 0.35 or less, and the thermosetting resin sheet according to claim 1.

3. The thermosetting resin sheet according to claim 2, wherein the second thermosetting resin composition further contains a colorant.

4. The thermosetting resin sheet according to any one of claims 1 to 3, wherein the weight average molecular weights of the first polyol resin and the second polyol resin are each 50,000 or more and 1,000,000 or less.

5. The thermosetting resin sheet according to any one of claims 1 to 4, wherein the first polyol resin and the second polyol resin each contain at least a (meth)acrylic resin having a plurality of hydroxyl groups.

6. The thermosetting resin sheet according to any one of claims 1 to 5, wherein the reaction start temperatures of the first curing agent and the second curing agent are both 180°C or lower.

7. A vehicle painted using the thermosetting resin sheet according to any one of claims 1 to 6.

8. A vehicle part painted using the thermosetting resin sheet according to any one of claims 1 to 6.

9. A method for manufacturing a vehicle, comprising a step of painting using the thermosetting resin sheet according to any one of claims 1 to 6.

10. A method for manufacturing a vehicle part, comprising a step of painting using the thermosetting resin sheet according to any one of claims 1 to 6.

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