Thermosetting resin sheet, vehicle, vehicle component, and method for producing vehicle and vehicle component

Abstract

Provided is a curable resin sheet equipped with a resin layer comprising a curable resin composition, wherein a tanδ peak first appears at 20°C or higher when tanδ is measured at -80°C or higher, which is the low temperature side, after the curable resin composition has been thermally cured for one hour at 160°C.

Description

Thermosetting resin sheet, vehicle, 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 sheet, and a method for manufacturing the vehicle and the vehicle part.

[0002] Furniture, steel plates, vehicle bodies, and the like are coated with exterior paint for the sake of design and durability. It is known that exterior coating is performed using films, such as decorative films, and various types of decorative films have been developed for such applications. For example, Patent Document 1 discloses a thermosetting coating sheet that is in an uncured or semi-cured state and can retain its sheet shape, and that contains as its main components an acrylic resin, a monomer having multiple functional groups as a crosslinking agent that reacts with isocyanate groups, and a blocked isocyanate.

[0003] Patent No. 2688105

[0004] Incidentally, when exterior paint deteriorates or has defects, it is often repaired by scraping it off, and the exterior paint formed using the above-mentioned decorative film also needs to be repaired in the same way. Therefore, the decorative film is required to be easy to scrape off so as to ensure sufficient workability during repair. However, conventional decorative films have not been designed to ensure sufficient workability during repair, and there is a problem that scraping the film takes time and effort.

[0005] Therefore, an object of the present invention is to provide a thermosetting resin sheet having a resin layer that is easy to scrape off during repair work or the like.

[0006] As a result of extensive investigation, the present inventors have found that the above-mentioned problems can be solved by configuring a thermosetting resin sheet to include a resin layer in which, when tan δ is measured from a low temperature of −80° C. after the resin layer has been thermally cured at 160° C. for 1 hour, the first peak of tan δ that appears is 20° C. or higher. That is, the present invention provides the following [1] to [9].

[0007] [1] A thermosetting resin sheet having a resin layer made of a thermosetting resin composition, wherein the resin layer, after being thermally cured at 160°C for 1 hour, exhibits a first peak in tan δ at 20°C or higher when measured by dynamic viscoelasticity measurement from -80°C to 250°C. [2] The thermosetting resin sheet according to [1], wherein the first peak in tan δ appears at 200°C or lower. [3] The thermosetting resin sheet according to [1] or [2], wherein the thermosetting resin composition contains a (meth)acrylic resin and a compound having a blocked isocyanate group. [4] The thermosetting resin sheet according to [3], wherein the (meth)acrylic resin contains a (meth)acrylic resin having multiple functional groups and a weight-average molecular weight of 50,000 to 1,000,000. [5] The thermosetting resin sheet according to any one of [1] to [4], wherein the resin layer comprises a clear layer and a colored layer containing a colorant. [6] A vehicle painted using the thermosetting resin sheet according to any one of [1] to [5]. [7] A vehicle part painted using the thermosetting resin sheet according to any one of [1] to [5]. [8] A method for manufacturing a vehicle, comprising a step of painting using the thermosetting resin sheet according to any one of [1] to [5]. [9] A method for manufacturing a vehicle part, comprising a step of painting using the thermosetting resin sheet according to any one of [1] to [5].

[0008] According to the present invention, it is possible to provide a thermosetting resin sheet having a resin layer that is easy to scrape off during repair work or the like.

[0009] 1 is a schematic cross-sectional view showing an example of a thermosetting resin sheet, and FIG. 2 is a schematic cross-sectional view showing an example of a thermosetting resin sheet.

[0010] [Curable Resin Sheet] (Resin Layer) The thermosetting resin sheet of the present invention includes a resin layer made of a thermosetting resin composition, and is characterized in that after the resin layer is thermally cured at 160°C for 1 hour, the first peak of tan δ measured by dynamic viscoelasticity measurement from -80°C to 250°C appears at 20°C or higher.

[0011] If the first peak of tan δ appears below 20°C, the resin layer becomes difficult to scrape. For example, during repair work on the exterior paint, scraping the resin layer requires time and effort, making it difficult to ensure workability. From this perspective, the first peak of tan δ preferably appears at 40°C or higher, more preferably at 60°C or higher, and even more preferably at 75°C or higher. Furthermore, from the viewpoint of preventing cracks from occurring in the resin layer, for example, during repair work on the resin layer, the first peak of tan δ preferably appears at 200°C or lower, more preferably at 180°C or lower, and even more preferably at 150°C or lower. As will be described later, in the case of a multilayer structure such as a two-layer structure including a colored layer and a clear layer, the tan δ of the multilayer resin layer can be measured directly, and the measurement results should satisfy the above requirements. In the case of a multilayer structure, tan δ peaks of each layer may be detected. In such a case, it is preferable that all of the tan δ peaks in each layer first appear at 20°C or higher. As will be described later, the resin layer is preferably attached to the object to be coated, and after being completely cured while attached to the object to be coated, the coating of the object to be coated is formed.

[0012] In the present invention, the first peak of tan δ is determined by measuring tan δ from -80°C to 250°C using dynamic viscoelasticity measurement, plotting a graph with temperature on the horizontal axis and tan δ on the vertical axis, and determining the first peak that appears on the graph as the first peak of tan δ. The position where the slope of the tangent to the tan δ curve changes from positive to negative is considered the peak of tan δ. Even if the tan δ peak splits into multiple peaks at its apex, if they are located within ±5°C of the largest peak, they are considered to be a single peak, and the largest peak is considered to be the peak. Furthermore, if a next peak appears within a short interval of 5°C after the appearance of one peak, and subsequent peaks appear at short intervals (with adjacent peaks spaced within 5°C), the largest of these peaks is considered to be the peak. Furthermore, small fluctuations in tan δ, such as noise or shoulders, are not considered to be peaks of tan δ. For example, peaks that fall below any tan δ value within a ±5°C range from the peak position are considered to be noise or shoulders. The conditions for measuring the dynamic viscoelasticity are as described in the Examples below.

[0013] The temperature at which the tan δ peak first appears can be adjusted to a desired range depending on the components contained in the thermosetting resin composition. For example, it can be easily increased by using a thermosetting resin with a high glass transition temperature or hydroxyl value. That is, it can be appropriately adjusted by the amount of functional groups in the thermosetting resin. Furthermore, when two or more types of thermosetting resins are used, it can be easily increased by blending more of the thermosetting resin with the higher glass transition temperature than the thermosetting resin with the lower glass transition temperature. Furthermore, when a plasticizing resin is contained, the temperature of the first peak of tan δ can also be adjusted by the plasticizing resin. Usually, the temperature of the first peak of tan δ is lowered by blending a plasticizing resin. In addition, it can also be adjusted by the amount of curing agent; increasing the amount of curing agent tends to increase the temperature of the first peak of tan δ.

[0014] (Curable Resin) The thermosetting resin composition contains a curable resin. The curable resin preferably has a functional group, and the functional group is preferably a functional group that reacts with a reactive group (e.g., an isocyanate group) of a curing agent such as a compound having a blocked isocyanate group, which will be described later. Specific examples of the functional group include a hydroxyl group, a carboxyl group, and an amino group, and among these, a hydroxyl group is preferred. The curable resin may have only one type of functional group, or may have two or more types. It is also preferable that two or more functional groups are contained in one molecule.

[0015] Examples of the curable resin include (meth)acrylic resin, polycarbonate resin, polyester resin, and epoxy resin, among which (meth)acrylic resin is preferred. Furthermore, it is preferred to use a compound having a blocked isocyanate group as the curing agent. Therefore, it is preferred that the thermosetting resin composition forming the resin layer contains a (meth)acrylic resin and a compound having a blocked isocyanate group.

[0016] <(Meth)acrylic Resin> The (meth)acrylic resin used in the thermosetting resin composition may be a (meth)acrylic resin having multiple functional groups. Specific examples of the functional group include a hydroxyl group, a carboxyl group, and an amino group, with a hydroxyl group being preferred among these. The (meth)acrylic resin may have only one type of functional group, or may have two or more types. Of these, it is preferable that the (meth)acrylic resin has a hydroxyl group. Therefore, it is preferable that the (meth)acrylic resin is a (meth)acrylic polyol having multiple hydroxyl groups.

[0017] The (meth)acrylic resin is preferably an acrylic polymer obtained by polymerizing a monomer mixture containing a (meth)acrylic acid ester monomer and a functional group-containing monomer having the above-mentioned functional group, such as a hydroxyl group, an amino group, or a carboxyl group. Such an acrylic polymer can contain a functional group by using the functional group-containing monomer. The monomer mixture may also contain a monomer other than the (meth)acrylic acid ester monomer and the functional group-containing monomer, such as a styrene derivative monomer. Note that (meth)acrylic refers to either methacrylic or acrylic, and the same applies to other similar terms.

[0018] Examples of the (meth)acrylic acid ester monomer include (meth)acrylic acid ester monomers that do not have the above-mentioned functional group, and examples thereof include alkyl (meth)acrylates having an alkyl group with 1 to about 18 carbon atoms, such as methyl (meth)acrylate, ethyl (meth)acrylate, and 2-ethoxyethyl (meth)acrylate; (meth)acrylates having an aromatic ring, such as benzyl (meth)acrylate and phenoxydiethylene glycol (meth)acrylate; and 2-ethoxyethyl (meth)acrylate.

[0019] Examples of functional group-containing monomers include hydroxyl group-containing monomers, amino group-containing monomers, and carboxyl group-containing monomers. These may be used alone or in combination of two or more. Among the above-mentioned functional group-containing monomers, hydroxyl group-containing monomers are preferred. The above-mentioned (meth)acrylic polyol can be obtained by polymerizing a monomer mixture containing a (meth)acrylic acid ester monomer and a hydroxyl group-containing monomer.

[0020] 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. 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, o-chlorostyrene, and the like.

[0021] 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. In this case, the other monomer or polymer may be an acrylic, styrene, maleic acid, imide, silicone, or fluorine-based monomer, or a polymer of these monomers. Furthermore, the functional group of an acrylic polymer obtained by polymerizing a monomer mixture containing a (meth)acrylic acid ester monomer and a functional group-containing monomer may be reacted with a (meth)acryloyl group-containing compound having a reactive group capable of reacting with the functional group and a (meth)acryloyl group, thereby incorporating the (meth)acryloyl group into the acrylic polymer.

[0022] The thermosetting resin composition preferably contains, as the (meth)acrylic resin, a (meth)acrylic resin (hereinafter also referred to as (meth)acrylic resin (A)) that is solid and has a weight average molecular weight (Mw) of 50,000 or more and 1,000,000 or less, and has multiple functional groups. Since the (meth)acrylic resin (A) has a weight average molecular weight within the above range and is solid, it is easy to maintain the resin layer in a constant shape even before curing, making it easier to properly form the resin layer on, for example, a transfer layer. It also makes it easy to impart tackiness and extensibility to the resin layer. The resin layer has tackiness and extensibility, which allows it to be vacuum molded without tearing or the like during vacuum molding. Furthermore, when the weight average molecular weight is within the above range, it is easy to increase the hardness of the resin layer after curing. From the above viewpoints, the weight average molecular weight of the (meth)acrylic resin (A) is preferably 150,000 or more, more preferably 180,000 or more, and preferably 500,000 or less, more preferably 450,000 or less. In this specification, the weight average molecular weight (Mw) is measured by gel permeation chromatography (GPC) and is calculated as a value converted into standard polystyrene. Furthermore, being solid means being solid at room temperature (23°C) and normal pressure (1 atm).

[0023] The glass transition temperature (Tg) of the (meth)acrylic resin (A) is preferably 10°C or higher, more preferably 20°C or higher, and even more preferably 25°C or higher. If the glass transition temperature (Tg) of the (meth)acrylic resin (A) is above the above lower limit, the first peak of tan δ is likely to appear at 20°C or higher, making it easier to scrape the resin layer during repair work, etc. The upper limit of the glass transition temperature (Tg) of the (meth)acrylic resin (A) is not particularly limited, but is preferably 90°C or lower, more preferably 80°C or lower, and even more preferably 60°C or lower, so that the first peak of tan δ appears in an appropriate temperature range and prevents cracks from occurring in the resin layer during repair work, etc. In this specification, the glass transition temperature of the (meth)acrylic resin is a value determined by differential scanning calorimetry (DSC) in accordance with JIS K 7121.

[0024] The high molecular weight (meth)acrylic resin (A) is preferably a (meth)acrylic polyol having a plurality of hydroxyl groups (hereinafter also referred to as (meth)acrylic polyol (A')). As described above, the (meth)acrylic polyol (A') can be obtained, for example, by polymerizing a monomer mixture containing a (meth)acrylic acid ester monomer and a hydroxyl group-containing monomer. The hydroxyl value of the (meth)acrylic polyol (A') is preferably 20 mg KOH / g or more, more preferably 50 mg KOH / g or more, and even more preferably 60 mg KOH / g or more. When the hydroxyl value is set to the above lower limit, the first peak of tan δ tends to appear above 20 ° C., making it easier to scrape the resin layer during repair work, etc. The upper limit of the hydroxyl value is not particularly limited, but is preferably 220 mg KOH / g or less, more preferably 200 mg KOH / g or less, and even more preferably 180 mg KOH / g or less, from the viewpoint of preventing cracks in the resin layer during repair work, etc., by making the first peak of tan δ appear in an appropriate temperature range. The hydroxyl value can be measured in accordance with JIS K 1557-1:2007.

[0025] The thermosetting resin composition may contain, as the curable resin, a resin having a weight-average molecular weight of less than 50,000 (hereinafter also referred to as a plasticizing resin) in addition to the high molecular weight (meth)acrylic resin (A). By containing a plasticizing resin having a low weight-average molecular weight in addition to a high molecular weight (meth)acrylic resin, the thermosetting resin composition can easily achieve a good balance of the coatability of the thermosetting resin composition, the curability, tackiness, and extensibility of the resin layer. Examples of resins used as the plasticizing resin include (meth)acrylic resins, polycarbonate resins, polyester resins, and epoxy resins. Among these, (meth)acrylic resins or polycarbonate resins are preferred, and (meth)acrylic resins are more preferred. The weight-average molecular weight of the plasticizing resin is preferably 500 or more and 30,000 or less, more preferably 1,000 or more and 20,000 or less.

[0026] The (meth)acrylic resin used as the plasticizing resin (hereinafter also referred to as (meth)acrylic resin (a)) includes an oligomer having a functional group such as a hydroxyl group, an amino group, a carboxyl group, etc. Examples of the (meth)acrylic resin used as the plasticizing resin are as described above for the (meth)acrylic resin.

[0027] The glass transition temperature of the (meth)acrylic resin (a) used as the plasticizing resin is not particularly limited, but is preferably less than 0° C., more preferably −20° C. or less, even more preferably −40° C. or less, and preferably −120° C. or more, more preferably −100° C. or more, and even more preferably −80° C. or more. When the glass transition temperature of the (meth)acrylic resin (a) is within the above range, the first peak of tan δ tends to appear at 20° C. or more, making it easier to scrape the resin layer during repair work and the like, and also making it easier to develop tackiness.

[0028] The (meth)acrylic resin (a) is preferably a (meth)acrylic polyol having a plurality of hydroxyl groups (hereinafter also referred to as (meth)acrylic polyol (a')). The hydroxyl value of the (meth)acrylic polyol (a') is preferably 20 mg KOH / g or more and 250 mg KOH / g or less, more preferably 50 mg KOH / g or more and 200 mg KOH / g or less. By setting the hydroxyl value within the above range, the first peak of tan δ tends to appear at 20 ° C or more, making it easier to scrape the resin layer during repair work, etc., and improving tackiness, etc.

[0029] The content of the (meth)acrylic resin in the thermosetting resin composition is not particularly limited, but is preferably 20% by mass or more and 85% by mass or less, more preferably 25% by mass or more and 80% by mass or less, and even more preferably 30% by mass or more and 75% by mass or less, based on the total amount of the thermosetting resin composition. By setting the content of the (meth)acrylic resin within the above range, an appropriate hardness is imparted to the resin layer, which makes it easier to scrape the resin layer during repair work, for example, thereby improving workability. Note that 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 refers to the value based on the solids content excluding the volatile component.

[0030] When (meth)acrylic resin (A) and (meth)acrylic resin (a) are used in combination, the content of (meth)acrylic resin (a) is preferably 55% by mass or less, more preferably 50% by mass or less, and even more preferably 45% by mass or less, based on the total amount of (meth)acrylic resin. By setting the content of (meth)acrylic resin (a) to the above upper limit or less, the first peak of tan δ tends to appear at 20 ° C or higher, making it easier to scrape the resin layer during repair work, etc. Furthermore, the lower limit of the content of (meth)acrylic resin (a) is not particularly limited, but from the viewpoint of easily imparting excellent tackiness to the resin layer, it is preferably 3% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, based on the total amount of (meth)acrylic resin.

[0031] (Blocked Isocyanate) A compound having a blocked isocyanate group (hereinafter also referred to as "blocked isocyanate") is a compound in which an isocyanate group is blocked with a protecting group. When exposed to high temperatures, the protecting group (blocking agent) is thermally dissociated and removed, causing a curing reaction between the resulting isocyanate group and a functional group in the above-mentioned thermosetting resin (typically, a hydroxyl group of a polyol). Blocked isocyanates can be obtained, for example, by reacting an isocyanate compound having two or more isocyanate groups in one molecule with a blocking agent.

[0032] The isocyanate compound having two or more isocyanate groups in one molecule is not particularly limited, and examples thereof include tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, isocyanurate group-containing isocyanate compounds, and modified versions thereof. Among these, at least one selected from an isocyanurate modified version of hexamethylene diisocyanate and an isocyanurate modified version of an isocyanurate group-containing isocyanate compound is preferred, with an isocyanurate modified version of hexamethylene diisocyanate being more preferred. As the isocyanurate modified version of an isocyanurate group-containing isocyanate compound, one in which at least one other isocyanurate ring is bonded to one isocyanurate ring is preferred, and one in which three other isocyanurate rings are bonded to one isocyanurate ring is more preferred.

[0033] By using these compounds as an isocyanate compound having two or more isocyanate groups in one molecule, the first peak of tan δ tends to appear at 20° C. or higher, making it easier to scrape the resin layer during repair work, etc. Furthermore, by using an isocyanurate-modified hexamethylene diisocyanate, a certain level of hardness is imparted to the resin layer, making it easier to prevent cracks from occurring in areas other than the scraped area during repair work of the resin layer, for example.

[0034] Examples of blocking agents include pyrazole, phenols, oximes, lactams, and malonic acid esters. Among these, pyrazole is preferred. The content of the blocked isocyanate in the thermosetting resin composition is adjusted so that the ratio of the number of functional groups in the curable resin to the number of isocyanate groups in the blocked isocyanate is preferably 0.4 to 1.8, more preferably 0.6 to 1.5.

[0035] The curing agent used in the thermosetting resin composition of the present invention is not limited to blocked isocyanates, and melamine-based compounds and the like may also be used. The melamine-based compound is a compound having a melamine skeleton within the compound, and any compound capable of undergoing a dehydration condensation reaction may be used. Examples of such compounds include alkylolated melamine derivatives such as monomethylolmelamine and hexamethylolmelamine obtained by reacting melamine with formaldehyde under alkaline conditions, compounds partially etherified by reacting an alkylolated melamine derivative with an alcohol, and mixtures thereof. The melamine-based compound may be a monomer or a dimer or higher polymer, or a mixture thereof may be used.

[0036] <Other Components> In addition to the thermosetting resin and curing agent, the thermosetting resin composition may contain appropriate components according to the performance required for the coating formed from the resin layer. For example, when the coating formed from the resin layer is a colored coating, a colorant such as a pigment, dye, or luster material may be added to make the resin layer a colored layer. When the coating formed from the resin layer is a heat-shielding coating, a heat-shielding material may be added to the thermosetting resin composition to make the resin layer a heat-shielding layer. The resin layer may also contain components other than those described above, for example, additives other than those described above. Examples of additives include crosslinking agents, dispersants, inorganic fillers other than pigments and luster materials, anti-aging agents, antioxidants, and rust inhibitors. Furthermore, the resin layer may be made into a clear layer, as described below. Among these, it is preferable that the thermosetting resin composition contains at least a colorant.

[0037] Examples of pigments used as colorants include, but are not limited to, 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. Known dyes can be used, including azo dyes, anthraquinone dyes, indigoid dyes, and stilbene dyes. Luster materials are compounds that can impart luster to the resin layer and provide it with the property of exhibiting gloss when observed from multiple directions. The luster material is not particularly limited, but examples include compounds in which a titanium oxide layer is provided on the surface of natural mica, synthetic mica, alumina flakes, glass flakes, etc. The resin layer preferably contains at least one of a pigment or a luster material as a colorant, and more preferably a pigment. It is also preferable for the resin layer to contain both a pigment and a luster material. The content of the colorant in the thermosetting resin composition is not particularly limited, but is, for example, about 0.1 to 25% by mass, preferably 0.3 to 20% by mass, and more preferably 0.5 to 12% by mass. In addition to the above-mentioned components such as the colorant and heat-shielding material, the thermosetting resin composition may also contain additives such as inorganic fillers, catalysts such as urethanization catalysts, curing accelerators, surface conditioners, antifoaming agents, crosslinking agents, dispersants, antioxidants, antioxidants, and ultraviolet absorbers.

[0038] The resin layer may have a single-layer structure consisting of a single layer, or may have a multi-layer structure consisting of two or more layers, but a single-layer structure is preferable. The single-layer structure makes it easier to scrape the resin layer during repair work, etc. When the resin layer has a multi-layer structure, each layer may be made of the above-mentioned thermosetting resin composition. Furthermore, each layer may contain a colorant as described above to form a colored layer, or may contain a heat-shielding material to form a heat-shielding layer, or may be a clear layer that does not substantially contain a colorant.

[0039] In the case of a multi-layer structure, the resin layer preferably has at least a colored layer and a clear layer. When the resin layer has a colored layer and a clear layer and a transfer layer (described later) is provided, the clear layer and the colored layer are preferably arranged in this order from the transfer layer side. With such a layer configuration, when the thermosetting resin sheet is attached to an object to be coated, the colored layer and the clear layer are arranged in this order from the object to be coated. By having the colored layer, the object to be coated can be colored by the paint formed by the resin layer. Furthermore, by providing a clear layer in addition to the colored layer, the colored layer can be protected or glossy. The colored layer preferably contains a pigment as a colorant, and therefore, it is particularly preferable that the resin layer has a clear layer and a colored layer.

[0040] Both the colored layer and the clear layer may be made of the above-described thermosetting resin composition, and the thermosetting resin composition for the colored layer may contain a colorant as described above. Furthermore, when a (meth)acrylic resin is used as the thermosetting resin, the thermosetting resin composition for the colored layer may contain at least a high molecular weight (meth)acrylic resin. A high molecular weight (meth)acrylic resin (A) and a low molecular weight (meth)acrylic resin (a) may also be used in combination. On the other hand, the clear layer is a transparent layer, and may have a transparency sufficient to allow the color of the colored layer to be visible from the outside through the clear layer. For example, the transmittance of light at a wavelength of 450 nm may be 80% or more. The clear layer may be a resin layer that does not contain a colorant, but may contain a small amount of a colorant as long as it does not impair its function. Furthermore, when a (meth)acrylic resin is used as the thermosetting resin, the thermosetting resin composition for the clear layer may contain at least a high molecular weight (meth)acrylic resin. In this case, a plasticizing resin may or may not be contained.

[0041] Of course, when the resin layer has a multi-layer structure, it is not limited to a two-layer structure of a clear layer and a colored layer, and various laminate structures are possible, such as a three-layer or more structure with two or more colored layers and one or more clear layers, or a structure consisting of two colored layers without the clear layer. Also, two or more clear layers may be provided. Furthermore, a heat-shielding layer or the like may be provided between the clear layer and the colored layer, resulting in a three-layer or more structure.

[0042] The thickness of the resin layer is not particularly limited, but is, for example, 20 μm to 200 μm, preferably 30 μm to 100 μm. When a colored layer and a clear layer are provided on the resin layer, the thickness of the colored layer is not particularly limited, but is, for example, 10 μm to 100 μm, preferably 15 μm to 50 μm. The thickness of the clear layer is not particularly limited, but is, for example, 10 μm to 100 μm, preferably 15 μm to 50 μm.

[0043] (Transfer Layer) The thermosetting resin sheet of the present invention may include at least a resin layer. For example, as shown in FIG. 1 , a thermosetting resin sheet 10 may include a resin layer 11 and a transfer layer 12, with the resin layer 11 formed on one side of the transfer layer 12. The transfer layer protects the resin layer from scratches and foreign matter adhesion and serves as a support when attaching the resin layer to an object to be coated. 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 (PBT) and polyethylene terephthalate (PET), polyamide resins, polycarbonate resins, acrylic resins, fluororesins, vinyl chloride resins (PVC) such as soft vinyl chloride resins, polymethylpentene resins, tetrafluoroethylene resins, and acrylonitrile-butadiene-styrene copolymer (ABS) resins. The cyclic polyolefin resin is a polymer containing structural units derived from a cyclic olefin. The polyolefin resin is a polyolefin resin other than the cyclic polyolefin resin, specifically, polypropylene resin (PP), polyethylene resin (PE), etc. Examples of the polyethylene resin include low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene (LLDPE). These resins can be used alone or in combination of two or more. Among these resins, cyclic olefin resin, PET, PBT, PVC, ABS, PE, and PP are preferred from the viewpoints of vacuum moldability and transferability.

[0044] 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 resin layer side. However, the transfer layer does not need to be release-treated as long as it can be peeled from the resin 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 20 μm or more and 600 μm or less, and more preferably 30 μm or more and 400 μm or less.

[0045] (Other Layers) The thermosetting resin sheet 10 may also have layers other than the transfer layer 12. For example, as shown in FIG. 2 , the thermosetting resin sheet 10 may include a release film 13, which may be attached to the surface of the resin layer 11. When the transfer layer 12 is provided, the release film 13 may be provided on the surface of the resin layer 11 opposite the side on which the transfer layer 12 is provided. The release film 13 is not particularly limited as long as a known release film is used, but it may be made of a resin film, or at least one surface of the resin film may be release-treated with a release agent such as a silicone-based release agent, a non-silicone-based (organic release agent), or a fluorine-based release agent. When the release film 13 is release-treated, the release-treated surface may be positioned in contact with the resin layer 11. The release film 13 may be peeled from the resin layer 11 and removed from the thermosetting resin sheet 10 before attaching the thermosetting resin sheet 10 to the substrate. Furthermore, although not shown, the thermosetting resin sheet 10 may include a support layer instead of a release film, and the support layer may be attached to the surface of the resin layer 11. The support layer may be formed of resin, rubber, or the like. Similarly to the release film, the support layer may have a release-treated surface that comes into contact with the resin layer 11. The support layer may be provided on the surface of the resin layer 11 opposite to the side on which the transfer layer 12 is provided.

[0046] [Method for producing thermosetting resin sheet] The method for producing the thermosetting resin sheet of the present invention is not particularly limited, but for example, it is preferable to prepare a coating liquid in which a thermosetting resin composition is diluted with a solvent, apply the coating liquid to a transfer layer composed of a resin film or the like, and dry it to produce the sheet. The coating liquid is not particularly limited, but it may be obtained, for example, by mixing each component constituting the thermosetting resin composition, including a thermosetting resin, a curing agent, a pigment, and other additives, into a solvent.

[0047] Examples of the solvent include ethyl acetate, butyl acetate, toluene, etc., and ethyl acetate is preferred from the viewpoints of ease of obtaining a desired thermosetting resin sheet, workability, etc. The amount of the solvent used is not particularly limited, but is, for example, from 50 parts by mass to 1,000 parts by mass, preferably from 100 parts by mass to 500 parts by mass, relative to 100 parts by mass of the thermosetting resin such as the (meth)acrylic resin.

[0048] The method for applying the coating liquid to the transfer layer is not particularly limited, and it is preferable to apply the coating liquid to the transfer layer using a known coating device.

[0049] 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 10 minutes or higher and 60 minutes or lower, more preferably 15 minutes or higher and 45 minutes or lower.

[0050] The drying temperature in this drying step is preferably 85°C or higher and 130°C or lower, and more preferably 90°C or higher and 120°C or lower. When the drying temperature is equal to or higher than these lower limits, the solvent is easily removed appropriately from the coating liquid, and vaporization of the solvent and the like when curing the resin layer is prevented, which causes bubbles to form. Furthermore, by setting the temperature equal to or lower than the upper limit, it is possible to prevent the curable resin composition from curing more than necessary during drying. The drying time in this drying step is preferably 10 minutes or higher and 60 minutes or lower, and more preferably 15 minutes or higher and 45 minutes or lower. By setting the drying time equal to or higher than the lower limit, it is possible to easily remove the solvent appropriately from the coating liquid, and it is possible to prevent vaporization of the solvent and the like when curing the resin layer, which causes bubbles to form. Furthermore, by setting the temperature equal to or lower than the upper limit, it is possible to prevent the curable resin composition from curing more than necessary during drying.

[0051] Furthermore, the dried resin layer may be subjected to initial curing as needed. Initial curing refers to curing the curable resin composition constituting the resin layer to a semi-cured state. Initial curing is preferably performed by heating. When initial curing is performed by heating, it is preferably performed under conditions of a heating temperature of 135°C or higher and 150°C or lower, and a heating time of approximately 5 minutes or higher and 10 minutes or lower.

[0052] (Method of using thermosetting resin sheet) The thermosetting resin sheet of the present invention is not particularly limited, but is preferably used to form a coating on various articles (objects to be coated). That is, the thermosetting resin sheet is preferably used as a decorative sheet. Specifically, after attaching a transfer resin sheet to various objects to be coated, the resin layer is cured, and the cured resin layer is used as the coating. The transfer layer is preferably peeled from the resin layer attached to the object to be coated and removed from the object to be coated.

[0053] The substrate to be coated with the thermosetting resin sheet is not particularly limited, but examples thereof include vehicle parts typified by electrical appliances, automotive interior materials, and interior materials for transportation equipment other than automobiles; automotive exterior materials and exterior materials for transportation equipment other than automobiles; electrical appliances, miscellaneous goods, heavy machinery, ships, and aircraft exterior materials; exterior walls or roofing materials for houses and buildings; bridges, steel frames, plants, and wind power generation blades. Among these, vehicle parts are preferred. That is, thermosetting resin sheets are preferably used for vehicle decoration. Among vehicle parts, vehicle exterior materials such as automotive exterior materials are more preferred. Examples of vehicle exterior materials include hoods, roofs, door panels, bumpers, fuel filler panels, trunk lids, and rear gates. When the thermosetting resin sheet is attached to a vehicle exterior material, it may be attached to the exterior material attached to the vehicle body, or it may be attached to the exterior material before being attached to the vehicle body. The material of the object to be coated is not particularly limited, and may be any of a resin material, an inorganic material such as ceramic, or a metal material such as steel, with metal materials being preferred among these. Metal materials such as steel are difficult to paint simultaneously with molding the object to be coated by 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.

[0054] The method for attaching the thermosetting resin sheet to the substrate is not particularly limited, and may be performed by hand using a squeegee or the like, or by using a laminating device. Also, the sheet may be attached by press molding, insert injection, vacuum molding, or the like, but among these, vacuum molding is preferred. When attaching by vacuum molding, the transfer resin sheet may be heated to, for example, 90°C or higher and 130°C or lower, preferably 100°C or higher and 125°C or lower, and then vacuum molded.

[0055] The thermosetting resin sheet may be pre-shaped by vacuum forming, press forming, compressed air forming, or the like to form a shape corresponding to the shape of the object to be coated, and then attached to the object to be coated. When pre-shaping is performed, the thermosetting resin sheet is preferably pre-shaped in a state in which a support layer is attached to the resin layer. Pre-shaping is performed by using a jig to form the thermosetting resin sheet into a certain shape, but pre-shaping the thermosetting resin sheet in a state in which it has a support layer can prevent the resin layer from sticking to the jig. Among the above methods, pre-shaping is preferably performed by vacuum forming. Furthermore, the pre-shaped thermosetting resin sheet may be attached to the object to be coated after the support layer is removed. In this case, the thermosetting resin sheet may be attached by hand, by using a laminating device to attach to the object to be coated, or by other methods.

[0056] The thermosetting resin sheet attached to the substrate as described above may have its resin layer cured. When the curable resin composition is heat-curable, the resin layer may be cured by heating. When curing by heating, the heating temperature is not particularly limited as long as the resin layer can be cured, but is, for example, 135°C or higher and 175°C or lower, and preferably 140°C or higher and 165°C or lower. The heating time is, for example, 30 minutes or higher and 90 minutes or lower, and preferably 45 minutes or higher and 70 minutes or lower.

[0057] The resin layer constituting the thermosetting resin sheet of the present invention is easy to scrape after curing, thereby providing excellent workability when repairing the resin layer. The resin layer may be scraped, for example, when the resin layer deteriorates over time or defects occur, making it necessary to replace the resin layer. After scraping the original resin layer, a new thermosetting resin sheet may be attached to the area where the original resin layer was located, so that a new resin layer is provided on the substrate. The method for scraping the resin layer is not particularly limited, but may be performed using, for example, abrasive paper such as a file, abrasive film, abrasive cloth, abrasive belt, or the like. The resin layer may be scraped until it is completely removed from the substrate. Furthermore, when the resin layer has a two-layer structure consisting of a colored layer and a clear layer, both layers may be scraped until they are completely removed from the substrate.

[0058] The present invention also provides a method for manufacturing a vehicle or a vehicle part. The method for manufacturing a vehicle or a vehicle part of the present invention includes a step of painting using the thermosetting resin sheet of the present invention. In the painting step, the vehicle or vehicle part may be painted by the method described in the above-mentioned method of use.

[0059] 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.

[0060] The methods for measuring and evaluating various physical properties in the present invention are as follows.

[0061] [Tan δ Peak Temperature] A resin layer measuring 350 mm x 5 mm was cut out from the resin layer produced in each Example and Comparative Example to prepare a sample. The sample was thermally cured at 160°C for 1 hour, and then dynamic viscoelasticity measurement was carried out under the following conditions, and the temperature at which the first peak of tan δ was detected in the temperature range of -80°C to 250°C was determined. <Measurement Conditions> Measurement device: Dynamic viscoelasticity measurement device (product name "DVA-200", manufactured by IT Measurement Control Co., Ltd.) Tension mode, 10 Hz, strain: 0.02%, temperature range: -80 to 250°C, heating rate: 1°C / min

[0062] [Paint scraping ability] The thermosetting resin sheet obtained in each example and comparative example was attached to a coated steel plate so that the resin layer was in contact with the coated steel plate, and then the transfer layer was peeled off to obtain an evaluation sample. The sample was subjected to a Taber abrasion test in accordance with JIS K7204, and the paint scraping ability was evaluated. The evaluation criteria are as follows: A: The thickness of the paint scraped by the abrasive wheel was 75 μm or more. B: The thickness of the paint scraped by the abrasive wheel was 50 μm or more but less than 75 μm. C: The thickness of the paint scraped by the abrasive wheel was 50 μm or more, but the paint cracked in areas other than those scraped by the abrasive wheel. D: The thickness of the paint scraped by the abrasive wheel was less than 50 μm.

[0063] The components used in the examples and comparative examples are as follows. <(Meth)acrylic Resins> High molecular weight acrylic polyol resin (A1): weight average molecular weight 250,000, glass transition temperature (Tg) 40°C, hydroxyl value 80 mgKOH / g, solid content (NV) = 29.6 mass% (solvent: ethyl acetate) High molecular weight acrylic polyol resin (A2): weight average molecular weight 250,000, glass transition temperature (Tg) 40°C, hydroxyl value 170 mgKOH / g, solid content (NV) = 29.6 mass% (solvent: ethyl acetate) High molecular weight acrylic polyol resin (A3): weight average molecular weight 250,000, glass transition temperature (Tg) -50°C, hydroxyl value 80 mgKOH / g, solid content (NV) = 38.2 mass% (solvent: ethyl acetate) High molecular weight acrylic polyol resin (A4): weight average molecular weight 230,000, glass transition temperature (Tg) 10°C, hydroxyl value 110 mgKOH / g, solid content (NV) = 35.2 mass% (solvent: ethyl acetate) High molecular weight acrylic polyol resin (A5): weight average molecular weight 230,000, glass transition temperature (Tg) 10°C, hydroxyl value 15 mgKOH / g, solid content (NV) = 32 mass% (solvent: ethyl acetate)

[0064] Low molecular weight acrylic polyol resin (a1): "ARUFON UH-2041" manufactured by Toagosei Co., Ltd., weight average molecular weight 2500, glass transition temperature (Tg) -50°C, hydroxyl value 120 mg KOH / g, solid content (NV) = 100% by mass Low molecular weight acrylic polyol resin (a2): Polycarbonate diol, "PH-50" manufactured by UBE Co., Ltd., weight average molecular weight 500, hydroxyl value 224 mg KOH / g, solid content (NV) = 100% by mass

[0065] <Blocked isocyanate curing agent> Blocked isocyanate (B1): isocyanurate-modified hexamethylene diisocyanate-based blocked isocyanate (HDI-based), blocking agent type: pyrazole-based, solid content (NV) = 68 mass%, recycled NCO amount = 10.4, solvent: ethyl acetate

[0066] Blocked isocyanate (B2): an isocyanurate-modified isocyanurate-based blocked isocyanate in which three other isocyanurate rings are bonded to one isocyanurate ring; blocking agent type: pyrazole-based; solid content (NV) = 68 mass%; recycled NCO amount = 7.8; solvent: ethyl acetate

[0067] <Catalyst> Kusumoto Chemicals "XK-639", urethane catalyst

[0068] <Pigment> "NSP-UP 841B" manufactured by Nikko Bix Co., Ltd., effective pigment concentration = 9 mass%, solid content concentration (NV) = 24 mass% <Glittering material> "Xiramic T60-10 WNT Crystal Silver" manufactured by Merck KGaA, a material in which alumina flakes are coated with at least one layer of metal oxide containing titanium dioxide.

[0069] Example 1 A coating solution of a thermosetting resin composition was prepared by adding a high molecular weight acrylic polyol resin (A1), a low molecular weight acrylic polyol resin (a1), a blocked isocyanate, a pigment, a luster material, and a catalyst in the proportions shown in Table 1, and adding ethyl acetate as a solvent to obtain a solids concentration of 40% by mass. This coating solution was applied to the smooth surface of an unstretched cyclic polyolefin film (manufactured by Toray Industries, Inc., "Decofit Q16CK") constituting a transfer layer using an applicator. A drying process was then carried out at a drying temperature of 70°C for a drying time of 20 minutes to obtain a resin layer. This resin layer was then subjected to a main drying process at a drying temperature of 70°C for a drying time of 20 minutes to form an 80 μm-thick resin layer on the transfer layer. A thermosetting resin sheet having an 80 μm-thick resin layer formed on the transfer layer was obtained, and various evaluations were performed. The results are shown in Table 1.

[0070] [Examples 2 to 6, Comparative Examples 1 to 3] Thermosetting resin sheets were obtained and various evaluations were carried out in the same manner as in Example 1, except that the formulation of the thermosetting resin composition used to prepare the coating liquid was changed as shown in Tables 1 and 2. The results are shown in Tables 1 and 2.

[0071] [Example 7] A coating liquid of a thermosetting resin composition for a colored layer (hereinafter also referred to as Coating Liquid 1) was prepared by adding a high molecular weight acrylic polyol resin (A1), a low molecular weight acrylic polyol resin (a1), a blocked isocyanate, a pigment, a lustrous material, and a catalyst in the proportions shown in Table 2, and adding ethyl acetate as a solvent, so that the solids concentration was 40% by mass. Separately from the above composition, a coating liquid of a thermosetting resin composition for a clear layer (hereinafter also referred to as Coating Liquid 2) was prepared by adding a high molecular weight acrylic polyol resin (A1), a blocked isocyanate, and a catalyst in the proportions shown in Table 2, and adding ethyl acetate as a solvent, so that the solids concentration was 40% by mass.

[0072] Next, Coating Liquid 1 was applied to a release film using an applicator, and Coating Liquid 2 was applied to the smooth surface of an unstretched cyclic polyolefin film (manufactured by Toray Industries, Inc., "Decofit Q16CK") that constitutes the transfer layer using an applicator.

[0073] For coating liquid 1, the main drying process was carried out under conditions of a drying temperature of 70°C and a drying time of 20 minutes, forming a colored layer with a thickness of 30 μm on the release film. For coating liquid 2, the main drying process was carried out under conditions of a drying temperature of 70°C and a drying time of 20 minutes, forming a clear layer with a thickness of 30 μm on the transfer layer. The colored layer on the release film and the clear layer on the transfer layer were bonded together and laminated at 25°C to obtain a thermosetting resin sheet in which the release film, colored layer, clear layer, and transfer layer were laminated in this order, and various evaluations were performed. The results are shown in Table 2.

[0074]

[0075] *The amount of active ingredient in the pigment is the value in Tables 1 and 2 multiplied by 9 / 24.

[0076] As is clear from the above examples, the thermosetting resin sheet satisfying the requirements of the present invention had a temperature at which a tan δ peak first appeared of 20° C. or higher, which resulted in the coating film made of the thermosetting resin sheet being easy to scrape off. In contrast, the thermosetting resin sheet produced in the comparative example had a temperature at which a tan δ peak first appeared of less than 20° C., which resulted in the coating film made of the thermosetting resin sheet being difficult to scrape off.

[0077] 10 Thermosetting resin sheet 11 Resin layer 12 Transfer layer 13 Release film

Claims

1. A thermosetting resin sheet having a resin layer made of a thermosetting resin composition, wherein the resin layer is thermally cured at 160°C for 1 hour, and the first peak of tan δ measured by dynamic viscoelasticity measurement from -80°C to 250°C appears at 20°C or higher.

2. The thermosetting resin sheet according to claim 1, wherein the first peak of tan δ appears at 200°C or lower.

3. The thermosetting resin sheet according to claim 1 or 2, wherein the resin composition contains a (meth)acrylic resin and a compound having a blocked isocyanate group.

4. The thermosetting resin sheet according to claim 3, wherein the (meth)acrylic resin contains a (meth)acrylic resin having a plurality of functional groups and a weight average molecular weight of 50,000 or more and 1,000,000 or less.

5. A thermosetting resin sheet according to any one of claims 1 to 4, wherein the resin layer comprises a clear layer and a colored layer containing a colorant.

6. A vehicle painted with the thermosetting resin sheet according to any one of claims 1 to 5.

7. A vehicle part coated with the thermosetting resin sheet according to any one of claims 1 to 5.

8. A method for manufacturing a vehicle, comprising a step of painting using the thermosetting resin sheet according to any one of claims 1 to 5.

9. 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 5.

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