Transfer-type curable resin sheet for coating, and method for forming coating

Abstract

This transfer-type curable resin sheet for coating comprises a coating layer that is composed of a curable resin composition that can be cured by heat, moisture, or an active energy ray; and a transfer layer that is composed of a thermoplastic resin, wherein the tack value at 23 °C on the surface of the coating layer that is on the reverse side from the surface on which the transfer layer is provided is 300 N / cm2 to 4000 N / cm2.

Description

Transfer-type curable resin sheet for painting and method for forming paint

[0001] The present invention relates to a transfer-type curable resin sheet for coating, and a method for forming a coating using the transfer-type curable resin sheet for coating.

[0002] Conventionally, various products such as furniture, steel plates, and vehicle bodies have been painted to impart functions such as design, durability, weather resistance, and scratch resistance. When industrially painting products having three-dimensional shapes, the paint is generally sprayed by air or electrostatic force. Spray painting has the following drawbacks: loss during painting, CO2 emissions from factories, etc. ２ In view of the need for large-scale capital investment, replacement with decorative technology using resin films has been considered recently.

[0003] Decorative technology is a technology used in various fields, such as household electrical appliances, automotive interior parts, and miscellaneous goods, to decorate the surface of a product by attaching a resin film (decorative film) printed with letters or patterns using white, black, or color ink. For example, Patent Document 1 proposes a painted film as a decorative film, which has a protective layer formed on a film substrate from an active energy ray-curable composition. Patent Document 1 describes that the protective layer formed from an active energy ray-curable composition having a specific composition can improve the chemical resistance, scratch resistance, and other properties of the painted surface.

[0004] Patent No. 5394995

[0005] In the coated film disclosed in Patent Document 1, since the base film itself does not have adhesive properties, an adhesive layer made of an adhesive is generally formed on the surface opposite the protective layer in order to attach it to various products. However, when attached using an adhesive, peeling easily occurs over time, making it unsuitable for outdoor applications that require durability and weather resistance.

[0006] Furthermore, by using a paint film as disclosed in Patent Document 1, a surface layer equivalent to a paint can be formed on the surface of a plastic molded product by insert molding so that the surface is decorated with the paint film while molding the plastic raw material supplied from an injection mold. However, because this method presupposes injection molding, it is difficult to apply it to materials other than plastic materials, such as steel plate materials.

[0007] For application to steel plate materials, etc., vacuum forming can be considered for application, but with vacuum forming, the film itself must have adhesive properties in order to be properly attached to the surface of various products. On the other hand, if adhesive properties are given to the film itself, the film becomes flexible and vulnerable to scratches.

[0008] Therefore, an object of the present invention is to provide a transfer-type curable resin sheet for painting that can be appropriately attached to various articles by vacuum forming or the like and has excellent scratch resistance.

[0009] As a result of extensive investigations, the present inventors have found that the above-mentioned problems can be solved by providing a resin sheet with a transfer-type multilayer structure having a paint layer containing a curable resin composition and a transfer layer, and by setting the tack value at 23°C of the application surface of the paint layer within a certain range, and have completed the present invention as described below. That is, the present invention provides the following [1] to [7]. [1] A transfer-type curable resin sheet for painting, comprising a paint layer containing a curable resin composition that can be cured by heat, moisture, or active energy rays, and a transfer layer containing a thermoplastic resin, wherein the tack value at 23°C of the surface of the paint layer opposite to the surface on which the transfer layer is provided is 300 N / cm ２ More than 4000N / cm ２[2] The transfer-type curable resin sheet for coating according to [1], wherein the transfer layer has a tensile elongation at break of 500% or more in both MD and TD at 120°C. [3] The transfer-type curable resin sheet for coating according to [1] or [2], wherein the transfer layer has a tensile elongation at break of 500% or more in both MD and TD at 100°C. [4] The transfer-type curable resin sheet for coating according to [1] to [3], wherein the curable resin composition contains a (meth)acrylic resin (A) having a weight-average molecular weight of 100,000 or more and 1,000,000 or less, which is solid and has a plurality of functional groups. [5] The transfer-type curable resin sheet for coating according to [4], wherein the (meth)acrylic resin (A) is a (meth)acrylic polyol (A1), and the curable resin composition contains a blocked isocyanate (B). [6] The transfer-type curable resin sheet for coating according to [4], wherein the (meth)acrylic resin (A) is a polymer (A2) having a (meth)acryloyl group and contains a radical polymerization initiator (C) that generates radicals when exposed to heat or active energy rays. [7] A method for forming a coating, comprising attaching the transfer-type curable resin sheet for coating according to any one of [1] to [6] to an object to be coated, and then curing the paint layer to form a coating. [8] The method for forming a coating according to [7], wherein the transfer layer is peeled off from the paint layer and removed from the object to be coated.

[0010] According to the present invention, it is possible to provide a transfer-type curable resin sheet for coating that can be appropriately adhered to various articles by vacuum forming or the like and has excellent scratch resistance.

[0011] Fig. 1 is a schematic cross-sectional view showing an example of a transfer-type curable resin sheet for coating. Fig. 2 is a schematic cross-sectional view showing an example of a transfer-type curable resin sheet for coating. Fig. 3 is a schematic cross-sectional view showing an example of a transfer-type curable resin sheet for coating. Fig. 4 is a schematic cross-sectional view showing an example of a method for forming a coating on an object to be coated. Fig. 5 is a schematic view of an apparatus for performing TOM molding. Fig. 6 is a schematic cross-sectional view showing an example of a method for forming a coating on an object to be coated.

[0012] The present invention will be described in more detail below using embodiments. The transfer-type curable resin sheet for coating of the present invention (hereinafter sometimes simply referred to as a "transfer-type resin sheet") is a multilayer sheet comprising a paint layer and a transfer layer. In the transfer-type resin sheet, the paint layer is formed on one side of the transfer layer, and the two are integrated. The paint layer contains a curable resin composition that can be cured by heat, moisture, or active energy rays. The transfer layer contains a thermoplastic resin. The transfer-type resin sheet is attached to various articles (hereinafter also referred to as "subjects") to be coated with the paint layer so that the paint layer contacts the subject. The paint layer is then cured to form a cured paint layer on the surface of the subject, and the cured paint layer forms a coating. The transfer layer may be peeled from the paint layer and removed from the subject after the paint layer has cured, for example.

[0013] The paint layer and transfer layer used in the transfer resin sheet will be described in detail below.

[0014] <Paint Layer> The paint layer constituting the transfer resin sheet of the present invention has a tack value at 23°C (hereinafter simply referred to as "tack value") of 300 N / cm on the surface opposite to the surface on which the transfer layer described below is provided. ２ More than 4000N / cm ２ If the tack value is less than the lower limit, the coating cannot adhere well to the substrate. If the tack value is more than the upper limit, the hardness of the cured coating cannot be sufficiently improved, and excellent scratch resistance cannot be imparted. From these viewpoints, the tack value is set to 500 N / cm ２ More than 3000N / cm ２ Preferably less than 700 N / cm ２ More than 2500N / cm ２The following are more preferred. The paint layer is used, for example, to protect or beautify the substrate, or to impart other unique functions. The paint layer may be a colored layer or a clear layer, as described below. Furthermore, the unique function of the paint layer can be, for example, a function as a heat-shielding coating. In this case, it is preferable that the coating formed by the paint layer functions as a heat-shielding coating. In this case, it is preferable to include a heat-shielding material in the thermosetting resin composition, and the paint layer can be used as a heat-shielding layer. Furthermore, by providing surface irregularities to the paint layer, it is possible to impart surface properties such as matte or grained finishes. Other functions such as rust prevention, mildew prevention, heat insulation, and antistatic properties can also be achieved by incorporating components appropriate for the purpose into the curable resin composition. The surface of the paint layer opposite the surface on which the transfer layer is provided becomes the surface to be attached to the substrate.

[0015] The paint layer used in the present invention is composed of a curable resin composition that can be cured by heat, moisture, or active energy rays. Examples of active energy rays include ionizing radiation such as ultraviolet rays, electron beams, α-rays, β-rays, and γ-rays, but any energy species can be used as long as it can generate radical active species. Among these, the curable resin composition is preferably a curable resin composition that can be cured by heat or active energy rays. The curable resin composition preferably contains a resin containing a functional group that can react with itself or a curing agent to cure by heat, moisture, or active energy rays. Resins used in the curable resin composition include curable resins. Specifically, resins that can be cured by heat or active energy rays include (meth)acrylic resins, polycarbonate resins, polyester resins, and epoxy resins, with (meth)acrylic resins being preferred. Furthermore, as a resin that can be cured by moisture, a moisture-curable resin can be used, as described below. Below, a detailed description is given of the case where at least a (meth)acrylic resin is used as the resin in the curable resin composition.

[0016] ((Meth)acrylic Resin) Examples of the (meth)acrylic resin include (meth)acrylic resins having multiple functional groups. The functional group is a group capable of reacting with heat or active energy rays. Preferred examples of the functional group include a functional group that reacts with a functional group (e.g., an isocyanate group) contained in the curing agent described below, and a functional group having a photopolymerizable unsaturated bond. Specific examples include a hydroxyl group, an amino group, a carboxyl group, a (meth)acryloyl group, a vinyl group, and a glycidyl group. The (meth)acrylic resin may have only one type of functional group, or two or more types. Among these, it is preferable that the (meth)acrylic resin have at least one of a hydroxyl group or a (meth)acryloyl group. Therefore, the (meth)acrylic resin is preferably a (meth)acrylic polyol having multiple hydroxyl groups, or a polymer having multiple (meth)acryloyl 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, 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.

[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] As the polymer having a (meth)acryloyl group, like the acrylic polymer described above, the main chain preferably has an acrylic skeleton having a structural unit derived from a (meth)acrylic acid ester; however, the main chain does not necessarily have to have an acrylic skeleton, and as long as it has a (meth)acryloyl group, the main chain does not necessarily have to have an acrylic skeleton, and may have, for example, a urethane skeleton.

[0023] The curable resin composition preferably contains, as the (meth)acrylic resin, a (meth)acrylic resin (hereinafter referred to as (meth)acrylic resin (A)) that has a weight-average molecular weight (Mw) of 100,000 or more and 1,000,000 or less, is solid, and has multiple functional groups. The (meth)acrylic resin (A) has a weight-average molecular weight within the above range and is solid, which makes it easier to maintain a consistent shape of the paint layer even before curing, making it easier to properly form the paint layer on the transfer layer. It also makes it easier to impart tackiness and extensibility to the paint layer. The tackiness and extensibility of the paint layer make it easier to adhere to the substrate without tearing during vacuum molding or the like, improving vacuum moldability. Furthermore, a weight-average molecular weight within the above range makes it easier to increase the hardness of the paint layer after curing. From the above viewpoints, the weight average molecular weight of the (meth)acrylic resin (A) is preferably 150,000 or more and 500,000 or less, more preferably 180,000 or more and 450,000 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, "solid" refers to a material that is solid at room temperature (23°C) and normal pressure (1 atm). Similarly, "liquid" refers to a material that is liquid at room temperature (23°C) and normal pressure (1 atm).

[0024] The glass transition temperature (Tg) of the (meth)acrylic resin (A) is preferably less than 90°C, more preferably 80°C or less, even more preferably 60°C or less, and preferably 0°C or more, more preferably 10°C or more. When the glass transition temperature of the (meth)acrylic resin (A) is within the above range, it becomes easier to impart a certain level of tackiness and extensibility to the paint layer. In this specification, the glass transition temperature is a value determined by differential scanning calorimetry (DSC) in accordance with JIS K 7121.

[0025] The high molecular weight (meth)acrylic resin (A) is preferably at least one of a (meth)acrylic polyol having multiple hydroxyl groups (hereinafter also referred to as (meth)acrylic polyol (A1)) or a polymer having (meth)acryloyl groups (hereinafter also referred to as polymer (A2)). As described above, the (meth)acrylic polyol (A1) 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 (A1) is preferably 20 mgKOH / g or more and 200 mgKOH / g or less, more preferably 30 mgKOH / g or more and 150 mgKOH / g or less. By setting the hydroxyl value within the above range, curability is improved, making it easier to achieve high hardness for the paint layer after curing. The hydroxyl value can be measured in accordance with JIS K1557-1:2007.

[0026] The polymer (A2) preferably has a predetermined proportion of (meth)acryloyl groups, specifically, the (meth)acryloyl group equivalent is preferably 100 g / mol or more and 10,000 g / mol or less, more preferably 500 g / mol or more and 8,000 g / mol or less. By setting the (meth)acryloyl group equivalent within the above range, the curability of the coating layer containing the polymer (A2) is improved, and the coating layer is easily hardened after curing. The (meth)acryloyl group equivalent means the value obtained by dividing the weight average molecular weight of the polymer by the number of (meth)acryloyl groups in one molecule of the polymer.

[0027] The content of the (meth)acrylic resin (A) in the paint layer is not particularly limited, but is, for example, 18% by mass or more, preferably 19% by mass or more, and more preferably 20% by mass or more, based on the total amount of the curable resin composition. By including a certain amount or more of the (meth)acrylic resin (A), the coatability and curability of the curable resin composition are easily improved. The content of the (meth)acrylic resin (A) in the paint layer is also not particularly limited, but is, for example, 60% by mass or less, preferably 55% by mass or less, and more preferably 50% by mass or less, based on the total amount of the curable resin composition. By reducing the content of the (meth)acrylic resin (A), the tackiness of the curable resin composition is easily improved. In this specification, the term "based on the total amount of the curable resin composition" means that, when the curable resin composition contains a solvent such as a solvent, the sum of the components excluding the solvent is 100% by mass. In other words, the term "based on the total amount of the curable resin composition" means the total solids content of the curable resin composition. The (meth)acrylic resin (A) may be used alone or in combination of two or more kinds.

[0028] The curable resin composition preferably contains, as a resin, a plasticizing resin (a) having a weight-average molecular weight of less than 100,000 in addition to the (meth)acrylic resin (A). The plasticizing resin (a) is preferably one that can plasticize the curable resin composition before curing and adjust the tack value of the paint layer to the desired range. The plasticizing resin (a) is preferably one that is compatible with the (meth)acrylic resin (A) and, like the (meth)acrylic resin (A), has a functional group that can be cured by heat or active energy rays. Resins used in the plasticizing resin (a) include (meth)acrylic resins, polycarbonate resins, polyester resins, epoxy resins, polyether resins, polyolefin resins, and plant-derived resins (such as castor oil), with (meth)acrylic resins or polycarbonate resins being preferred. The curable resin composition contains a plasticizing resin (a) in addition to a high-molecular-weight (meth)acrylic resin (A), which facilitates a good balance of the curable resin composition's tackiness, coatability, curability of the paint layer, extensibility, etc. The weight-average molecular weight of the plasticizing resin (a) is preferably 100 or more and 30,000 or less, more preferably 300 or more and 20,000 or less.

[0029] Furthermore, the above-mentioned plasticized resin (a) is desirably a liquid at a solids content of 100%. The plasticized resin (a) may or may not have a glass transition temperature. When the plasticized resin (a) has a glass transition temperature, the glass transition temperature is not particularly limited, but is preferably below 0°C, more preferably below -20°C, and even more preferably below -40°C. The lower limit of the glass transition temperature is not particularly limited, but is, for example, -120°C or higher, preferably -100°C or higher. When the glass transition temperature of the plasticized resin (a) is within the above range, it becomes easier to adjust the tensile elongation at break of the paint layer to a desired range, and tackiness also becomes easier to exhibit.

[0030] The plasticizing resin (a) is preferably at least one of a (meth)acrylic polyol or polycarbonate diol having multiple hydroxyl groups (hereinafter also referred to as polyol (a1)) and a polymer having (meth)acryloyl groups (hereinafter also referred to as polymer (a2)). The hydroxyl value of the (meth)acrylic polyol or polycarbonate diol (polyol (a1)) is preferably 20 mg KOH / g or more and 300 mg KOH / g or less, more preferably 50 mg KOH / g or more and 250 mg KOH / g or less. By setting the hydroxyl value within the above range, curability is improved, making it easier to achieve high hardness for the paint layer after curing. The polymer (a2) having (meth)acryloyl groups has a (meth)acryloyl group equivalent of preferably 10 g / mol or more and 10,000 g / mol or less, more preferably 100 g / mol or more and 8,000 g / mol or less. By setting the (meth)acryloyl group equivalent within the above range, the curability is improved, and it becomes easier to achieve high hardness in the coating layer after curing.

[0031] The (meth)acrylic polyol or polycarbonate diol (polyol (a1)) is preferably used when the high molecular weight (meth)acrylic resin (A) is the (meth)acrylic polyol (A1). By using the (meth)acrylic polyol or polycarbonate diol (polyol (a1)) in combination with the (meth)acrylic polyol (A1), the curable resin composition is more likely to be properly cured by heating. Furthermore, the polymer (a2) is preferably used when the high molecular weight (meth)acrylic resin (A) is a polymer (A2) having a (meth)acryloyl group. By using the polymer (a2) in combination with the polymer (A2), the curable resin composition is more likely to be properly cured by irradiation with active energy rays, heating, or the like. The plasticizing resin (a) may be used alone or in combination of two or more types.

[0032] In the coating layer, the ratio of the total content of the plasticizing resin (a) and the blocked isocyanate (B) to the (meth)acrylic resin (A) (hereinafter also referred to as "(a + B) / A") is, for example, 0.8 or more, preferably 0.9 or more, and more preferably 1.0 or more. When (a + B) / A is a certain value or more, that is, when the coating layer contains a certain value or more of the plasticizing resin (a) and the blocked isocyanate (B), the tack value of the curable resin composition can be made to be a certain value or more, and adhesion and other properties can be easily improved. Furthermore, (a + B) / A is, for example, 5 or less, preferably 4.5 or less, and more preferably 4 or less. When (a + B) / A is made to be a certain value or less, the hardness of the cured product of the curable resin composition can be made to be a certain value or more, and excellent scratch resistance can be imparted. Note that when the curable resin composition contains a solvent such as a solvent, (a + B) / A is the blending ratio based on the total solid content as described above. The same applies to a / A described below.

[0033] (Blocked Isocyanate (B)) The curable resin composition of the present invention may contain a curing agent that reacts with the above-described curable resin to cure it. The curing agent is preferably a heat-curing agent that reacts with the curable resin by heating. When a (meth)acrylic polyol (A1) is used as the heat-curing agent, a blocked isocyanate (B) is preferably used. That is, in one embodiment, the curable resin composition of the present invention preferably contains a (meth)acrylic polyol (A1) and a blocked isocyanate (B).

[0034] The blocked isocyanate (B) 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 the (meth)acrylic polyol (A1), (meth)acrylic polyol, or polycarbonate diol (polyol (a1)). The blocked isocyanate (B) can be obtained, for example, by reacting an isocyanate compound having two or more isocyanate groups per molecule with a blocking agent. 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 active methylenes.

[0035] The amount of blocked isocyanate (B) in the curable resin composition is preferably such that the ratio of the number of functional groups in the (meth)acrylic polyol (A1) to the number of isocyanate groups in the blocked isocyanate (B) (number of functional groups / number of isocyanate groups) is 0.4 to 2.5, and more preferably 0.6 to 1.4. The content of blocked isocyanate (B) is not particularly limited, but is preferably 20 to 50% by mass, and more preferably 25 to 45% by mass, based on the total amount of the curable resin composition.

[0036] (Radical Polymerization Initiator (C)) The curable resin composition of the present invention may contain a radical polymerization initiator (C) that generates radicals when exposed to heat or active energy rays. When a polymer (A2) having a (meth)acryloyl group is used in the curable resin composition, it is preferable to use the radical polymerization initiator (C). That is, in one embodiment, the curable resin composition of the present invention preferably contains a polymer (A2) having a (meth)acryloyl group and a radical polymerization initiator (C).

[0037] Examples of thermal radical polymerization initiators that generate radicals by heat include azo compounds and organic peroxides. Examples of azo compounds include 2,2'-azobis(2,4-dimethylvaleronitrile) and azobisisobutyronitrile. Examples of organic peroxides include benzoyl peroxide, ketone peroxide, peroxyketal, hydroperoxide, dialkyl peroxide, peroxyester, diacyl peroxide, and peroxydicarbonate. Examples of photoradical polymerization initiators that generate radicals by active energy rays include benzophenone-based compounds, alkylphenone-based compounds, acetophenone-based compounds, acylphosphine oxide-based compounds, titanocene-based compounds, oxime ester-based compounds, benzoin ether-based compounds, and thioxanthone. As the radical polymerization initiator (C), a photoradical polymerization initiator is preferred.

[0038] The content of the radical polymerization initiator (C) in the curable resin composition is preferably 0.01 mass % or more and 10 mass % or less, more preferably 0.1 mass % or more and 7 mass % or less, and even more preferably 0.2 mass % or more and 5 mass % or less, based on the total amount of the curable resin composition. When the content of the radical polymerization initiator (C) is within these ranges, the curable resin composition can be cured with high curability by heating or irradiation with active energy rays.

[0039] When the curable resin composition is to be a curable resin composition that can be cured by moisture, it is preferable to include a moisture-curable resin in the composition. Examples of moisture-curable resins include prepolymers having isocyanate groups at their terminals. Examples of prepolymers having isocyanate groups at their terminals include those obtained by reacting a polyisocyanate with an active hydrogen-containing compound and / or an active hydrogen-containing polymer. Examples of polyisocyanates used in preparing prepolymers having isocyanate groups at their terminals include tolylene diisocyanate, crude tolylene diisocyanate, diphenylmethane diisocyanate, polymethylene polyphenyl isocyanate, carbazimidated diphenylmethane diisocyanate, phenylene diisocyanate, 1,5-naphthalene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, etc., and preferably polymethylene polyphenyl isocyanate is used.

[0040] Examples of the active hydrogen-containing compound and active hydrogen-containing polymer that can be used include: active hydrogen-containing compounds such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, glycerin, trimethylolethane, trimethylolpropane, castor oil, diglycerin, sorbitol, pentaerythritol, and dipentaerythritol; and active hydrogen-containing polymers having two or more terminal hydroxyl groups, an average molecular weight of 3,000 or less, an average functionality of 2 or more, preferably an average molecular weight of 200 to 1,000, and an average functionality of 2 to 2.5, which are obtained by addition polymerization of the above-mentioned active hydrogen-containing compounds with alkylene oxides such as ethylene oxide, propylene oxide, butylene oxide, styrene oxide, and tetrahydrofuran, either alone or in combination. Other active hydrogen-containing polymers that can be used in combination include polyester polyols, oil-modified polyester polyols, poly-ε-caprolactone polyols, polycarbonate diols, acrylic polyols, polyamines, polyamides, urea resins, and melamine resins, which have an average molecular weight of 3,000 or less and an average functionality of 1.5 or more, preferably an average molecular weight of 200 to 1,000 and an average functionality of 2 to 2.5. The prepolymers having terminal isocyanate groups have, for example, an effective NCO content of 1 to 15% by mass, preferably 8 to 13% by mass.

[0041] The prepolymer having a terminal isocyanate group can be synthesized by carrying out a urethanization reaction of the above polyisocyanate and a conventional polyol containing the above active hydrogen-containing polymer under conditions of excess isocyanate at a temperature of 40°C to 90°C, preferably 55°C to 75°C, in a moisture-free system.

[0042] The urethanization reaction is usually carried out in an organic solvent, and examples of such solvents include ketone solvents such as methyl ethyl ketone, ester solvents such as ethyl acetate, aromatic solvents such as toluene and xylene, and other solvents commonly used in paints. The urethanization reaction can also be carried out using a catalyst, such as a tertiary amine catalyst such as triethylamine or dimethylaniline, or a metal catalyst such as tin or zinc. These catalysts also function as catalysts when reacting with moisture in the air during coating film formation.

[0043] (Pigment (D)) The curable resin composition may contain a pigment (D). By containing the pigment (D) in the curable resin composition, the paint layer can be colored to form a colored layer, or the paint layer can be imparted with brilliance, etc. Therefore, the design of the paint formed by the transfer resin sheet can be improved. Examples of the pigment (D) include aluminum pigments such as aluminum flakes, luster pigments such as mica pigments, graphite pigments, and glass flake pigments, metal oxide pigments such as titanium oxide, iron oxide, and titanium yellow, 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, but are not limited to these.

[0044] The content of the active ingredient of the pigment (D) in the paint layer, i.e., the pigment component excluding the binder resin, dispersant, and additives, is, for example, 0.1% by mass or more and 50% by mass or less, preferably 0.5% by mass or more and 40% by mass or less, and more preferably 1% by mass or more and 30% by mass or less, based on the total amount of the curable resin composition. By setting the content of the pigment (D) at or above these lower limits, it is possible to appropriately color the paint formed by the transfer resin sheet or to appropriately impart luster to the paint. Furthermore, by setting the content of the pigment (D) at or below the above upper limits, it is possible to prevent the pigment (D) from deteriorating various properties of the paint layer, such as shape retention, curability, extensibility, and tackiness.

[0045] The curable resin composition may contain a colorant other than the pigment (D), or may contain a dye. Known dyes can be used as the dye, and examples thereof include azo dyes, anthraquinone dyes, indigoid dyes, and stilbene dyes. The curable resin composition may also contain components other than those described above, such as additives other than those described above. Examples of additives include adhesion promoters, urethane reaction catalysts, urethane reaction regulators, antifoaming agents, surface conditioners, wax additives, crosslinking agents, dispersants, inorganic fillers other than pigments, antioxidants, antioxidants, ultraviolet absorbers, and rust inhibitors.

[0046] The paint layer may have a single-layer structure or a multi-layer structure. In the case of a single-layer structure, the paint layer may consist of a single layer made of the curable resin composition. In the case of a multi-layer structure, each layer may consist of the curable resin composition described above. In the case of a multi-layer structure, for example, a plurality of layers made of the curable resin composition described above, each of which has a different composition from the other adjacent layers, may be laminated together. In the case of a multi-layer structure, the paint layer may comprise, for example, at least one of a colored layer containing a pigment or a colorant other than a pigment, and a clear layer containing neither a pigment nor a colorant other than a pigment. However, it is preferable for the paint layer to comprise both a colored layer and a clear layer. When a colored layer and a clear layer are provided, the clear layer and the colored layer are preferably arranged in this order from the transfer layer side. With this layer structure, when the transfer resin sheet is attached to an adherend, the colored layer and the clear layer are arranged in this order from the adherend side. As described above, the paint layer has a colored layer, which allows the adherend to be colored by the coating formed by the paint layer. Furthermore, providing a clear layer in addition to the colored layer can protect the colored layer or impart gloss to the colored layer.

[0047] The clear layer is a transparent layer, and it is sufficient that it has transparency to the extent that the color of the colored layer can be seen from the outside through the clear layer. For example, it is preferable that the transmittance of light with a wavelength of 450 nm is 80% or more. The clear layer is preferably a coating film that does not contain a colorant, but it may contain a small amount of colorant as long as it does not impair its function. Furthermore, when a (meth)acrylic resin is used as the curable resin, the curable resin composition for the clear layer only needs to contain at least a high molecular weight (meth)acrylic resin. In this case, it may or may not contain a plasticizing resin.

[0048] Of course, when the paint 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.

[0049] The thickness of the paint layer is not particularly limited, but is, for example, about 5 μm to 1000 μm, preferably 10 μm to 500 μm. When a colored layer and a clear layer are provided on the paint 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.

[0050] The curable resin composition constituting the paint layer may be in an uncured or semi-cured state. The uncured or semi-cured state refers to a state in which curing further progresses when the paint layer is heated or irradiated with active energy rays. The semi-cured state refers to a state in which the curable resin composition is partially cured, and the uncured state refers to a state in which the curable resin composition is not cured.

[0051] <Transfer Layer> In the transfer resin sheet of the present invention, the transfer layer serves as a support when transferring the paint layer to an adherend such as a vehicle body. The transfer layer preferably has a tensile elongation at break of 500% or more in both MD and TD at 120°C. If the tensile elongation at break of the transfer layer in both MD and TD is 500% or more, when the transfer resin sheet is attached to the substrate by vacuum forming or the like, the transfer resin sheet can easily conform to the shape of the substrate, making it easier to prevent breakage, wrinkles, etc., and to properly adhere the transfer resin sheet to the substrate. From the perspective of achieving excellent vacuum formability and properly adhering the transfer resin sheet to the substrate, the tensile elongation at break of the transfer layer in both MD and TD at 120°C is preferably 600% or more, and more preferably 700% or more. Further, the upper limit of the tensile elongation at break at 120°C is not particularly limited, but the tensile elongation at break in the MD and TD at 120°C may be, for example, 3000% or less.

[0052] The transfer layer preferably has a tensile breaking elongation of 500% or more in both MD and TD at 100°C. If the tensile breaking elongation of the transfer layer in both MD and TD is 500% or more, when the transfer resin sheet is attached to the substrate by vacuum forming or the like, the transfer resin sheet will easily conform to the shape of the substrate, making it easier to prevent breakage, wrinkles, etc., and to properly adhere the transfer resin sheet to the substrate. From the viewpoint of achieving excellent vacuum formability and properly adhering the transfer resin sheet to the substrate, the tensile breaking elongation of the transfer layer in both MD and TD at 100°C is preferably 600% or more, and more preferably 700% or more. Furthermore, there is no particular limitation on the upper limit of the tensile breaking elongation at 100°C, but the tensile breaking elongation in MD and TD at 120°C may be, for example, 3000% or less. The transfer layer only needs to have tensile elongation at break in both MD and TD within the above range at at least one of 100° C. and 120° C. For example, when the vacuum forming temperature is relatively high, the tensile elongation at break in both MD and TD should be within the above range at 120° C., and when the vacuum forming temperature is relatively low, the tensile elongation at break in both MD and TD should be within the above range at 100° C.

[0053] The tensile elongation at break of the transfer layer at 100°C and 120°C is the elongation at break measured in a tensile test of the film constituting the transfer layer, and can be measured by a measurement method in accordance with JIS K 7127. The tensile elongation at break of the transfer layer at 100°C and 120°C can be adjusted as appropriate depending on the type of resin constituting the transfer layer, whether or not the resin film constituting the transfer layer is stretched, the degree of stretching, etc.

[0054] The transfer layer is made of a thermoplastic resin. By using a thermoplastic resin as the transfer layer, the tensile elongation at break at at least one of 100°C and 120°C is increased, and when the transfer resin sheet is attached to the substrate, the transfer resin sheet can easily conform to the shape of the substrate. Furthermore, the occurrence of breaks, wrinkles, etc. is easily prevented, and the transfer resin sheet can easily be properly adhered to the substrate. Specific examples of thermoplastic resins include cyclic polyolefin resins, polyolefin resins, polyester resins, polyamide resins, acrylonitrile butadiene styrene resins, polycarbonate resins, acrylic resins, fluororesins, vinyl chloride resins, polymethylpentene resins, and tetrafluoroethylene resins. The use of these resins makes it easier to increase the tensile elongation at break.

[0055] 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 from 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.

[0056] 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, polypropylene 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).

[0057] The polyester resin is not particularly limited, but may be a polybutylene terephthalate (PBT) resin. The polybutylene terephthalate resin may be a homopolymer consisting of terephthalic acid units and 1,4-butanediol units, or may be a copolymer containing units derived from copolymerization components other than terephthalic acid units and 1,4-butanediol units. Examples of other copolymerization components include diol components and dicarboxylic acid components, and these may be contained in a proportion of, for example, 30 mol % or less of all units constituting the copolymer.

[0058] 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 transfer 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, a multilayer film may be formed by using different types of resins in each layer. 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 by mixing two or more types of resins.

[0059] Among the above, the resin used in the resin film is preferably one or more selected from cyclic polyolefin resins, polyolefin resins, and polyester resins. Among them, one or more selected from cyclic polyolefin resins, polypropylene resins, and PBT resins are more preferred. By using these resins, the solvent resistance of the transfer layer is likely to be increased, and even if the curable resin composition is diluted with a solvent and directly applied onto the transfer layer, deterioration of the transfer layer can be prevented. From these viewpoints, the resin used in the resin film is more preferably one or more selected from cyclic polyolefin resins and polypropylene resins, and even more preferably a cyclic polyolefin resin.

[0060] In addition, in the case of a multilayer film, it may be composed of a resin layer (also referred to as a first layer) composed of at least one resin selected from cyclic polyolefin resin, polypropylene resin, and PBT resin, and a resin layer (also referred to as a second layer) composed of a polyolefin resin such as polyethylene resin. For example, a multilayer film in which a first layer serving as a skin layer is provided on one or both sides of the second layer is also preferred. Specifically, a multilayer film in which a first layer composed of PBT resin is provided on one or both sides of a second layer composed of polyethylene resin is preferred. In this case, it is more preferable that a first layer (skin layer) is provided on both sides of the second layer (core layer). Note that when a first layer is provided on only one side of the second resin layer, it is preferable that the first layer is disposed on the paint layer side.

[0061] 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.

[0062] The resin film constituting the transfer layer may be a stretched film such as a uniaxially stretched film or a biaxially stretched film, or may be a non-stretched film, but a non-stretched film is preferred. When a stretched film is used, it is preferable to use a stretched film with a low stretch ratio. Using a non-stretched film or a stretched film with a low stretch ratio as the resin film makes it easier to increase the tensile elongation at break. The resin film may be a T-die film extruded through a T-die, or an inflation film.

[0063] 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, a non-silicone-based (organic 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 paint layer side. The release treatment of the transfer layer makes it easier to peel the transfer layer from the paint layer. The thickness of the transfer layer is not particularly limited, but is, for example, 30 μm or more and 300 μm or less, preferably 50 μm or more and 200 μm or less.

[0064] [Layer Structure] As shown in FIG. 1 , the transfer resin sheet 10 includes a paint layer 11 and a transfer layer 12, with the paint layer 11 formed on one side of the transfer layer 12 and integrated together. The paint layer 11 may be laminated directly on the transfer layer 12. The transfer resin sheet 10 may include the paint layer 11 and the transfer layer 12 as shown in FIG. 1 , but may also include other layers. For example, as shown in FIG. 2 , the transfer resin sheet 10 may include a release film 13, with the release film 13 attached to the surface of the paint layer 11. The release film 13 is not particularly limited as long as a known release film is used, but it may also 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. If the release film 13 is release-treated, the release-treated surface may be positioned in contact with the paint layer 11. The release film 13 is preferably peeled off from the paint layer 11 and removed from the transfer resin sheet 10 before the transfer resin sheet 10 is attached to the object to be coated.

[0065] 3, the transfer resin sheet 10 may include a support layer 14, and the support layer 14 may be attached to the surface of the paint layer 11. The support layer 14 may be made of resin, rubber, or the like. The surface of the support layer 14 that comes into contact with the paint layer 11 may be release-treated, similar to a release film.

[0066] (Method for manufacturing transfer resin sheet) The method for manufacturing the transfer resin sheet in the present invention is not particularly limited, but it is preferable to prepare a coating liquid in which a curable resin composition is diluted with a solvent, apply it to a transfer layer composed of a resin film or the like, and dry it to manufacture the sheet. The coating liquid is not particularly limited, but it may be obtained, for example, by mixing each component constituting the curable resin composition, such as a curable resin, a curing agent, a radical polymerization initiator, a pigment, and other additives, into a solvent.

[0067] Examples of the solvent include ethyl acetate, butyl acetate, toluene, etc., and ethyl acetate is preferred from the viewpoints of ease of obtaining the desired transfer 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 curable resin such as the (meth)acrylic resin.

[0068] 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.

[0069] 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.

[0070] 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 from the coating liquid, preventing the solvent from evaporating and causing bubbles when the paint layer is cured. Furthermore, by setting the temperature equal to or lower than the upper limit, the curable resin composition can be prevented from curing more than necessary during drying. The drying time in this drying step is preferably 10 minutes to 60 minutes, and more preferably 15 minutes to 45 minutes. By setting the drying time equal to or higher than the lower limit, the solvent is easily removed from the coating liquid, preventing the solvent from evaporating and causing bubbles when the paint layer is cured. Furthermore, by setting the temperature equal to or lower than the upper limit, the curable resin composition can be prevented from curing more than necessary during drying.

[0071] Furthermore, the transfer resin sheet after drying may be subjected to initial curing as needed. Initial curing refers to curing the curable resin composition constituting the paint layer to a semi-cured state. Initial curing may be performed by heating, by irradiation with active energy rays, or by moisture. When performing initial curing by heating, it is preferable to perform the initial curing 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.

[0072] (Method of using the transfer resin sheet) The transfer resin sheet of the present invention is used to form a coating on various articles (objects to be coated). Specifically, after attaching the transfer resin sheet to various objects to be coated, the paint layer is cured, and the cured paint layer is used as the coating. The transfer layer is preferably peeled off from the paint layer attached to the object to be coated and removed from the object to be coated.

[0073] Examples of objects to be painted with a transfer resin sheet include, but are not limited to, electrical appliances. Other examples include vehicle interior materials such as automobile and railcar interior materials, vehicle exterior materials such as automobile and railcar exterior materials, and miscellaneous goods. Other examples include exterior materials for heavy machinery, ships, and aircraft, exterior walls and roofs for houses and buildings, bridges, steel frames, plants, and wind power generation blades. Among these, vehicle exterior materials such as automobile exterior materials are preferred. Examples of vehicle exterior materials include hoods, roofs, door panels, bumpers, fuel filler panels, trunk lids, and rear gates. When applying a transfer resin sheet to a vehicle exterior material, the sheet may be applied to an exterior material attached to the vehicle body, or to an exterior material before attachment to the vehicle body. The material of the object to be painted is also not limited to, but may be any of resin materials, inorganic materials such as ceramics, and metal materials such as steel. Among these, metal materials such as steel are preferred. Metallic materials such as steel are difficult to paint at the same time as molding the object to be painted using insert molding, and painting with a resin sheet is difficult, but by using the transfer resin sheet of the present invention, such materials can be easily painted.

[0074] The method for attaching the transfer 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.

[0075] The transfer 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 curable resin sheet is preferably pre-shaped in a state in which the support layer 14 is attached to the paint layer 11 as shown in FIG. 3. Pre-shaping is performed by using a jig to form the transfer resin sheet into a certain shape, but pre-shaping the transfer resin sheet while it has the support layer can prevent the paint layer from sticking to the jig. Among the above methods, pre-shaping is preferably performed by vacuum forming. Furthermore, the pre-shaped transfer resin sheet may be attached to the object to be coated after the support layer is removed. In this case, the transfer resin sheet may be attached by hand, by using a laminating device to attach to the object to be coated, or by other methods.

[0076] The transfer resin sheet attached to the substrate as described above may have the paint layer cured. When the curable resin composition is heat-curable, the paint layer may be cured by heating. When curing by heating, the heating temperature is not particularly limited as long as the paint layer can be cured, but is, for example, 135°C or higher and 170°C or lower, preferably 140°C or higher and 160°C or lower. The heating time is, for example, 30 minutes or higher and 90 minutes or lower, preferably 60 minutes or higher and 90 minutes or lower.

[0077] In addition, when the curable resin composition can be cured by active energy rays, the coating layer may be cured by irradiating the active energy rays. As the active energy rays, ultraviolet rays (UV) are preferably used in terms of curability and convenience. The irradiation dose of the active energy rays is not particularly limited, but may be, for example, 200 mJ / cm. ２ More than 5000mJ / cm ２ or less, preferably 500 mJ / cm ２ More than 2000mJ / cm ２ In addition, when the curable resin composition can be cured by moisture, it is preferable to perform curing by moisture.

[0078] The transfer resin sheet has good vacuum formability due to the transfer layer having tensile breaking strength. Therefore, it is preferable to attach the transfer resin sheet to the object to be coated by vacuum forming. It is also preferable to pre-shape the sheet by vacuum forming before attaching it to the object to be coated. Below, with reference to Figure 4, a method of attaching a transfer resin sheet to the object to be coated by vacuum forming and forming a coating on the object to be coated will be described in more detail.

[0079] First, the object 20 to be coated is prepared, and the transfer resin sheet 10 is attached to the object 20 by vacuum forming, as shown in Figures 4(a) and (b). At this time, the transfer resin sheet 10 is attached to the object 20 to be coated so that the paint layer 11 is in contact with the object 20 to be coated. The transfer resin sheet 10 is also preferably tightly attached to the object 20 to be coated while being stretched and shaped to fit the shape of the object 20 to be coated by vacuum forming. Here, the vacuum forming is preferably TOM forming. TOM stands for "Three Dimension Overlay Method," and by applying TOM forming, the transfer resin sheet 10 can be attached to the object 20 to fit the shape of the object 20 to be coated.

[0080] FIG. 5 shows a schematic diagram of a TOM molding device. A transfer resin sheet 10 is set in a TOM molding device 30, with an upper box 31 above the transfer resin sheet 10 and a lower box 32 below the transfer resin sheet 10. Within the lower box 32, a workpiece 20 is placed on a vertically adjustable table 35. The transfer resin sheet 10 is arranged with the paint layer on the bottom and the transfer layer on the top. In this state, the upper box 31 and the lower box 32 are depressurized, and the transfer resin sheet 10 is heated using a near-infrared heater or the like. Next, the workpiece 20 is elevated by the vertically adjustable table 35, and the workpiece 20 and the transfer resin sheet 10 are pressure-bonded together. Compressed air is then introduced only into the upper box 11, and the upper box 31 and lower box 32 are held in this position for a certain period of time, thereby adhering the transfer resin sheet 10 to the surface of the workpiece 20. Of course, vacuum molding can be applied to methods other than TOM molding.

[0081] After the transfer resin sheet 10 is attached to the substrate 20, the paint layer 11 is then cured as shown in FIG. 4( c), and the cured paint layer 11 forms a coating on the substrate 20. The paint layer 11 may be cured by heating, by irradiation with active energy rays, or by moisture. Details of the heating and active energy ray irradiation conditions are as described above. Thereafter, as shown in FIG. 4( d), the transfer layer 12 may be peeled off from the paint layer 11 and removed from the substrate 20. However, the transfer layer 12 may also be peeled off from the paint layer 11 and removed from the substrate 20 before curing. Furthermore, as shown in FIG. 4( d), the paint layer 11 may be trimmed, i.e., unnecessary portions may be cut off as appropriate.

[0082] Next, referring to Figure 6, an example of a method for forming a coating using a transfer resin sheet that has been pre-shaped by vacuum forming will be described in detail. When pre-shaping is performed, as shown in Figure 6(a), for example, a transfer resin sheet 10 having a support layer 14, with the support layer 14 attached to the surface of the paint layer 11, is prepared, and a jig 40 is also prepared. The surface 40A of the jig 40 preferably has a shape that matches the surface shape of the object 20 to be coated. The jig 40 may be made of any material, and may be formed from a resin material or a metal.

[0083] The transfer resin sheet 10 having the support layer 14 is placed on the jig 40 so that the support layer 14 faces the surface 40A of the jig 40. As shown in FIG. 6( b), the transfer resin sheet 10 is brought into close contact with the jig 40 by vacuum forming, and the transfer resin sheet 10 is stretched and shaped into a shape corresponding to the surface shape of the object 20 to be coated. The vacuum forming conditions are as described above. Furthermore, the vacuum forming is preferably performed by TOM molding, but may also be performed by a method other than TOM molding. The specific method of TOM molding is as described above, but it is preferable to place the jig 40 in the TOM molding device 30 instead of the object 20 to be coated. The transfer resin sheet 10 pre-shaped as shown in FIG. 6( b) may be trimmed, i.e., unnecessary portions may be cut off as appropriate. The pre-shaped transfer resin sheet 10 is then removed from the jig 40 as shown in FIGS. 6(b) and 6(c), and the support layer 14 is preferably removed from the transfer resin sheet 10.

[0084] The transfer resin sheet 10, which has been pre-shaped and from which the support layer 14 has been removed, is attached to the object 20 to be coated, as shown in Figure 6(c). Here, the method for attaching the transfer resin sheet 10 to the object 20 to be coated is not particularly limited, and it may be attached by hand using a squeegee or the like, or by lamination using a laminating device. The transfer resin sheet 10 is pre-shaped to a shape corresponding to the surface shape of the object 20 to be coated, so it can be easily attached to the object 20 to be coated even by hand attachment or the like.

[0085] After the transfer resin sheet 10 is attached to the object 20, the paint layer 11 is then cured as shown in FIG. 6( d ), forming a coating on the object 20. The paint layer 11 may be cured by heating, by irradiation with active energy rays, or by moisture. Details of the heating and active energy ray irradiation conditions are as described above. The transfer layer 12 may also be peeled off from the paint layer 11 and removed from the object 20. The transfer layer 12 may be removed before the paint layer 11 is cured, but is preferably removed after curing.

[0086] 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.

[0087] The measurement and evaluation methods in the present invention are as follows.

[0088] <Tack Value of Paint Layer> The tack value of the paint layer was measured as follows. Specifically, the transfer curable resin for coating was set in a probe tack tester (TA-500, manufactured by UBM Corporation) so that the applied surface was in contact with the probe. Measurement was carried out under the following conditions, and the maximum load during peeling was evaluated as the tack value: probe diameter: 5 mm, speed: 10 mm / s, contact load: 100 gf, contact time: 1 s

[0089] <Tensile Breaking Elongation of Transfer Layer> The tensile breaking elongation of the transfer layer was measured by a measurement method in accordance with JIS K7127. Specifically, the film used for the transfer layer was cut into a dumbbell shape with a width of 10 mm and a gauge width of 25 mm, and then attached to a tensile tester. For Examples 1 to 8 and Comparative Examples 1 and 2, the film was pulled in a thermostatic chamber set at 120°C at a pulling rate of 100 mm / min, and the tensile elongation was calculated from the displacement at the point where the film broke using the following formula. For Examples 9 to 12 and Comparative Examples 3 and 4, the film was pulled in a thermostatic chamber set at 100°C at a pulling rate of 100 mm / min, and the tensile elongation was calculated from the displacement at the point where the film broke using the following formula. The jig width was the same as the gauge width. The tensile breaking elongation of the transfer layer was measured in both MD and TD. Tensile elongation (%) = (displacement at break / gauge width) x 100

[0090] <Scratch Resistance> Scratch resistance was measured using a pencil scratch in accordance with JIS K5600-5-4. Specifically, a measurement sample was prepared as follows. In Example 7, the prepared transfer resin sheet was attached to a baked painted plate, and then exposed to 3000 mJ / cm of UV light using an ultraviolet irradiator with a 365 nm LED lamp. ２After curing under the conditions, the transfer film was peeled off to prepare an evaluation sample. Except for Example 7, the transfer resin sheet was attached to a baked-coated board, the transfer film was peeled off, the paint layer was transferred to the baked-coated board, and the baked-coated board was then placed in a 160°C oven for 1 hour for thermal curing. A 1 kg load was applied to the surface of the cured paint layer at a 45° angle with a pencil, and after scratching 10 mm, the degree of scratching was confirmed and the highest pencil hardness that did not cause a scratch was indicated. The pencil used was a "Mitsubishi Pencil Uni (manufactured by Mitsubishi Pencil Co., Ltd.) certified by the Japan Paint Inspection Association." <Adhesion> Adhesion was evaluated as follows. First, water containing 0.5% polyalkyl ether surfactant was sprayed onto the baked-coated board. Next, the transfer resin sheet was placed so that the adhesive surface overlapped the baked-coated board, and then the transfer layer was rubbed with a squeegee to remove water and press the sheet together. After pressure bonding, the transfer layer was peeled off and the adhesion was evaluated based on the peeling behavior. A: The paint layer did not lift or peel off and the adhesion was successful. B: The paint layer lifted or peeled off and the adhesion was not successful.

[0091] <Vacuum Formability> The vacuum formability of the transfer resin sheets produced in each Example and Comparative Example was evaluated by TOM molding as shown below. A coating object (a test piece car shape manufactured by ASONE) was placed on a vertically adjustable table installed in a TOM molding machine (manufactured by Fuse Vacuum Co., Ltd., product name "NGF-0709-S") consisting of an upper box and a lower box. A curable resin sheet was then placed in a sheet clamp frame installed in the molding machine, with the paint layer on the bottom and the transfer layer on the top. The pressure inside the upper and lower boxes was then reduced to a gauge pressure of 0.0 kPa or less, and the transfer resin sheet was heated until its temperature reached 120°C. However, in Examples 9 to 12 and Comparative Examples 3 and 4, the transfer resin sheet was heated until its temperature reached 100°C. The coating object was then elevated to pressure-bond the coating object and the transfer resin sheet together, after which compressed air was introduced only into the upper box and held there for 5 seconds. The upper and lower boxes were opened to atmospheric pressure to obtain a laminate consisting of the object to be coated and the transfer resin sheet. The obtained laminate was observed, and its vacuum formability was evaluated according to the following criteria. A: The transfer resin sheet conformed to the three-dimensional shape of the object to be coated, and was in uniform adhesion. B: The transfer resin sheet was unable to conform to the three-dimensional shape of the object to be coated, and the sheet broke. Alternatively, wrinkles occurred throughout the sheet. -: The transfer resin sheet was deformed and could not be fixed with the sheet clamp of the molding machine, making it impossible to evaluate.

[0092] The components used in the examples and comparative examples, and the films used for the transfer layer are as follows: <(Meth)acrylic resin (A) and plasticizing resin (a)> The acrylic polyol, the reactive polymer containing an acroyl group, and the polycarbonate diol used are those shown in Table 1 below.

[0093] <Blocked isocyanate (B)> Hexamethylene diisocyanate-based blocked isocyanate (HDI-based), "Takenate B-882N" manufactured by Mitsui Chemicals, Inc., blocking agent type: 2-butanone oxime (MEKO), NV = 70%, solvent: petroleum naphtha, containing a small amount of urethane catalyst <Photoradical polymerization initiator (C)> Acetophenone-based compound, "Omnirad 1173" manufactured by BASF (NV = 100% by mass) <Pigment (D)> Pigment dispersion "NSP-UP 841B" manufactured by Nihon Bix Co., Ltd., effective pigment concentration = 9% by mass, NV = 24% by mass

[0094] <Film for transfer layer> Unstretched cyclic polyolefin film ("Decofit Q16CK" manufactured by Toray Industries, Inc., thickness 100 μm) Unstretched multilayer polybutylene terephthalate film Unstretched multilayer olefin film 1 ("Convenience Store PP" manufactured by Okamoto Corporation, thickness 100 μm) Unstretched multilayer olefin film 2 ("Convenience Store PE" manufactured by Okamoto Corporation, thickness 100 μm) Unstretched polyethylene terephthalate film ("Kanelon KA-20" manufactured by Shin-ei Kasei Co., Ltd., thickness 100 μm) Biaxially oriented polyethylene terephthalate film ("Cosmo Peel E7004" manufactured by Toyobo Co., Ltd.)

[0095] Example 1 According to the formulation shown in Table 2, 71 parts by mass of acrylic polyol (A1), 9 parts by mass of acrylic polyol (a1-(1)), and 20 parts by mass of blocked isocyanate (B) were mixed with thorough stirring to prepare a coating liquid of a curable resin composition. This coating liquid was applied with an applicator to the smooth surface of an unstretched cyclic polyolefin film ("Decofit Q16CK" manufactured by Toray Industries, Inc.) constituting a transfer layer. Next, a pre-drying step was carried out under conditions of a drying temperature of 60°C and a drying time of 30 minutes, followed by a main drying step under conditions of a drying temperature of 90°C and a drying time of 30 minutes, yielding a transfer resin sheet in which a 50 μm-thick coating layer was formed on the transfer layer. During this drying step, the solvent was removed from the coating liquid, and the resulting coating layer had the formulation shown in Table 3.

[0096] [Examples 2 to 5, 7 to 8, Comparative Examples 1 and 2] Transfer resin sheets were obtained in the same manner as in Example 1, except that the formulation of the curable resin composition used in the coating liquid and the film used in the transfer layer were changed as shown in Table 2. In Example 5, the pigment shown in Table 1 was also added to produce a transfer resin sheet.

[0097] Example 6 A transfer-type curable resin sheet for coating was prepared in the same manner as in Example 1, except that an unstretched multilayer polybutylene terephthalate film was used as the transfer layer film and the formulation of the curable resin composition used in the coating liquid was changed as shown in Table 2. The unstretched multilayer polybutylene terephthalate film was prepared as follows. The raw materials for the skin layer were prepared as follows. 100 parts by mass of polybutylene terephthalate resin (manufactured by Mitsubishi Engineering Plastics Corporation, trade name "NovaDuran 5010CS") and a nucleating agent (bis(4-methylbenzylidene)sorbitol, T ｍ = 200°C (manufactured by New Japan Chemical Co., Ltd., trade name: Gelall E-200) and 5 parts by mass were blended at a composition ratio of 100 parts by mass to 200°C, and then the mixture was melt-kneaded using a twin-screw extruder at a cylinder temperature of 250°C and pelletized to prepare a crystal nucleating agent masterbatch with a crystal nucleating agent concentration of 5% by mass. Next, a blend of the above-described polybutylene terephthalate and crystal nucleating agent masterbatch was used as a raw material. The amount of crystal nucleating agent added was 3 parts by mass of the crystal nucleating agent masterbatch per 100 parts by mass of polybutylene terephthalate, i.e., the amount of crystal nucleating agent added was 1500 ppm. A high-density polyethylene resin (manufactured by Japan Polyethylene Corporation, "Novatec HD") was used as the raw material for the core layer. In a three-layer T-die film molding machine equipped with three extruders with a screw diameter of 40 mm, each raw material was charged into each extruder, and molding was performed at a molding temperature of 250°C, a chill roll temperature of 80°C, and an air chamber static pressure of 15 mmH. ２ Under the conditions of O, a multilayer unstretched polybutylene terephthalate film (multilayer PBT film, thickness 200 μm) having a two-kind, three-layer structure in which both skin layers were PBT resin layers with a thickness of 50 μm and a core layer was a polyethylene resin layer with a thickness of 90 μm was obtained.

[0098] [Example 9] A transfer resin sheet was produced in the same manner as in Example 1, except that the tensile breaking elongation of the transfer layer was measured at 100°C, an unstretched multilayer olefin film 1 ("Convenience Store PP" manufactured by Okamoto Corporation, thickness 100 μm) was used as the transfer layer film, and the main drying process (drying temperature 90°C, drying time 30 minutes) was not performed.

[0099] [Example 10] A transfer resin sheet was produced in the same manner as in Example 2, except that the tensile breaking elongation of the transfer layer was measured at 100°C, an unstretched multilayer olefin film 2 ("Convenience Store PE" manufactured by Okamoto Corporation, thickness 100 μm) was used as the transfer layer film, and the main drying process (drying temperature 90°C, drying time 30 minutes) was not performed.

[0100] [Example 11] A transfer resin sheet was produced in the same manner as in Example 3, except that the tensile breaking elongation of the transfer layer was measured at 100°C, an unstretched polyethylene terephthalate film ("Kanelon KA-20" manufactured by Shin-ei Kasei Co., Ltd., thickness 100 μm) was used as the transfer layer film, and the main drying step (drying temperature 90°C, drying time 30 minutes) was not performed.

[0101] [Example 12] A transfer resin sheet was produced in the same manner as in Example 1, except that the tensile breaking elongation of the transfer layer was measured at 100°C, a biaxially stretched polyethylene terephthalate film (Cosmo Peel E7004 manufactured by Toyobo Co., Ltd.) was used as the transfer layer film, and the formulation of the curable resin composition used in the coating liquid was changed as shown in Table 3.

[0102] [Comparative Example 3] A transfer resin sheet was produced in the same manner as in Comparative Example 1, except that an unstretched multilayer olefin film 1 ("Convenience PE" manufactured by Okamoto Corporation, thickness 100 μm) was used as the transfer layer film, the tensile breaking elongation of the transfer layer was measured at 100°C, and the main drying process (drying temperature 90°C, drying time 30 minutes) was not performed.

[0103] [Comparative Example 4] A transfer resin sheet was produced in the same manner as in Comparative Example 2, except that an unstretched multilayer olefin film 1 ("Convenience PE" manufactured by Okamoto Corporation, thickness 100 μm) was used as the transfer layer film, the tensile breaking elongation of the transfer layer was measured at 100°C, and the main drying step (drying temperature 90°C, drying time 30 minutes) was not performed.

[0104]

[0105]

[0106] Table 4 below shows the content of each component based on the total solid content of the curable resin compositions in Examples 1 to 8 and Comparative Examples 1 and 2. However, the amount of the active ingredient in the pigment in Example 5 was 2 mass% based on the total solid content of the curable resin composition.

[0107]

[0108] In each of the above examples, by keeping the tack value of the paint layer on the application surface at 23°C within a certain range, transfer resin sheets with excellent scratch resistance and adhesion were produced. Furthermore, in Examples 1 to 7 and 9 to 11, a transfer layer with high tensile elongation at 120°C or 100°C was used, resulting in good vacuum formability, allowing the transfer resin sheet to conform to the three-dimensional shape of the substrate and adhere uniformly. This enabled the resin sheet to be vacuum formed into an appropriate coating. In contrast, in Comparative Examples 1 and 3, the tack value of the paint layer on the application surface at 23°C was low, resulting in insufficient adhesion to the substrate and insufficient adhesion. Furthermore, in Comparative Examples 2 and 4, the tack value of the paint layer on the application surface at 23°C was high and the hardness was insufficient, resulting in poor scratch resistance.

[0109] REFERENCE SIGNS LIST 10 Transfer-type curable resin sheet for coating 11 Paint layer 12 Transfer layer 13 Release film 14 Support layer 20 Object to be coated 30 TOM molding device 31 Upper box 32 Lower box 35 Up-down lift table 40 Jig

Claims

1. A transfer-type curable resin sheet for coating comprising a paint layer containing a curable resin composition that can be cured by heat, moisture, or active energy rays, and a transfer layer containing a thermoplastic resin, The tack value of the paint layer at 23° C. on the surface opposite to the surface on which the transfer layer is provided is 300 N / cm ２ More than 4000N / cm ２ The following is a transfer-type curable resin sheet for painting.

2. The transfer type curable resin sheet for coating according to claim 1 , wherein the transfer layer has a tensile breaking elongation of 500% or more in both MD and TD at 120° C.

3. 3. The transfer type curable resin sheet for coating according to claim 1, wherein the transfer layer has a tensile breaking elongation of 500% or more in both MD and TD at 100°C.

4. The coating transfer type curable resin sheet according to claim 1 or 2, wherein the curable resin composition contains a (meth)acrylic resin (A) that has a weight average molecular weight of 100,000 or more and 1,000,000 or less, is solid, and has a plurality of functional groups.

5. the (meth)acrylic resin (A) is a (meth)acrylic polyol (A1), The transfer-type curable resin sheet for coating according to claim 4 , wherein the curable resin composition contains a blocked isocyanate (B).

6. the (meth)acrylic resin (A) is a polymer (A2) having a (meth)acryloyl group, The transfer-type curable resin sheet for coating according to claim 4 , further comprising a radical polymerization initiator (C) which generates radicals by the action of heat or active energy rays.

7. A method for forming a coating, comprising attaching the transfer type curable resin sheet for coating according to claim 1 or 2 to an object to be coated, and then curing the paint layer to form a coating.

8. The method for forming a coating according to claim 7, further comprising peeling the transfer layer from the paint layer to remove the transfer layer from the substrate.