JP7819745B2 - Transfer sheets, resin molded products with transfer substrates, and resin molded products - Google Patents

Description

This disclosure relates to a transfer sheet, a resin molded product with a transfer substrate, and a resin molded product.

Lamination techniques using decorative sheets are used for surface protection and decorative design in resin molded products used in automobile interiors, building materials, home appliances, and other applications, as well as in resin molded products used with organic glass, which is used as an alternative to inorganic glass. Decorative sheets used in this type of technology can be broadly divided into laminate-type decorative sheets and transfer-type decorative sheets (i.e., transfer sheets).

Laminate-type decorative sheets are laminated on a supporting substrate with a protective layer positioned on the outermost surface, and are used so that the supporting substrate is incorporated into the resin molded product by laminating a molding resin on the supporting substrate side. On the other hand, transfer-type decorative sheets (transfer sheets) are laminated on a supporting substrate (transfer substrate) with a protective layer either directly or via an optional release layer. After laminating a molding resin layer on the side opposite the transfer substrate, the transfer substrate is peeled off, ensuring that no transfer substrate remains on the resin molded product. These two types of decorative sheets are used depending on the shape and desired function of the resin molded product.

Injection-molding decoration has been used to decorate resin molded products with complex surface shapes, such as three-dimensional curves. In this method, a decorative sheet inserted into an in-mold molding die is integrated with the molten resin injected into the cavity during injection molding, thereby decorating the surface of the resin molded product. Furthermore, depending on the structure of the decorative sheet integrated with the resin molded product (the aforementioned laminate-type and transfer-type decorative sheets (transfer sheets)), this method is generally broadly divided into injection-molding lamination decoration and injection-molding transfer decoration.

In the simultaneous injection molding transfer decoration method, the transfer sheet is placed with the transfer layer side facing the inside of the mold and heated from the transfer layer side using a heating platen. The transfer sheet is then attached to the mold and molded to fit the shape inside the mold. Next, molten injection resin is injected into the cavity and cooled to form a molded resin layer, integrating the transfer sheet and molded resin layer. The laminate with the integrated transfer sheet and molded resin layer is then removed from the mold, and the transfer substrate is peeled off to obtain a resin molded product including a transfer layer.

JP 2015-163434 A

To ensure that the transfer sheet and molded resin layer are properly integrated, an adhesive layer may be provided on the surface of the transfer sheet opposite the transfer substrate (the surface of the transfer layer). By providing an adhesive layer, the adhesion between the transfer layer and molded resin layer can be improved.

The type of resin used in the adhesive layer applied to the surface of the transfer sheet is selected according to the type of injected resin that forms the molded resin layer.

For example, molded products made from polyolefins such as polypropylene are often used in automobile parts due to their recyclability and lightweight design. Therefore, transfer sheets are used to decorate molded products (molded resin layers) made from polyolefins.

If the molded resin layer is formed from polyolefin, the adhesive layer of the transfer sheet that is adhered to the molded resin layer is required to contain polyolefin as an olefin component in order to enhance adhesion to the molded resin layer.

The inventors of the present disclosure have conducted research and have come to the new understanding that when a transfer sheet is used to decorate a molded product (molded resin layer) made from polyolefin, the weather resistance of the resulting resin molded product (specifically, deterioration of polyolefin-containing resin molded products due to ultraviolet rays) is insufficient, making the molded resin layer susceptible to deterioration. Through further research, the inventors of the present disclosure have discovered that, unlike the laminate-type decorative sheets described above, transfer-type decorative sheets (transfer sheets) tend to be thinner overall, and that even when a UV absorber is incorporated into the transfer sheet, their weather resistance is insufficient.

Furthermore, the inventors of the present disclosure considered improving the weather resistance of the transfer sheet by incorporating a large amount of UV absorber into the transfer layer of the transfer sheet. However, when a large amount of UV absorber is incorporated into the transfer layer, concerns arose that the design of the transfer layer would change depending on the color of the UV absorber, affecting the decoration of the resin molded product by the transfer layer.

In light of these circumstances, the primary objective of this disclosure is to provide a transfer sheet comprising at least a transfer substrate and a transfer layer laminated together, which has high adhesion to a molded resin layer containing polyolefin and can suppress deterioration of the resin molded product due to ultraviolet rays. Furthermore, the present disclosure also aims to provide a resin molded product with a transfer substrate that utilizes this transfer sheet, and a resin molded product from which the transfer substrate has been peeled off.

The inventors of the present disclosure conducted extensive research to solve the above-mentioned problems. As a result, they discovered that in a transfer sheet in which at least a transfer substrate and a transfer layer are laminated, the transfer layer comprises, in that order from the transfer substrate side, an ultraviolet absorbing layer and an adhesive layer, and the surface of the transfer layer opposite the transfer substrate side is composed of an adhesive layer, the adhesive layer contains polyolefin, and by setting the light transmittance (%) at a specific wavelength of the transfer layer to a predetermined value or less, the adhesive layer has high adhesion to a molded resin layer containing polyolefin and can effectively suppress deterioration of the molded resin layer containing polyolefin due to ultraviolet rays. The present disclosure was completed based on this knowledge and through further research.

That is, the present disclosure provides the inventions of the following aspects.
Item 1. A transfer sheet having at least a transfer substrate and a transfer layer laminated thereon,
the transfer layer includes an ultraviolet absorbing layer and an adhesive layer in this order from the transfer substrate side,
the surface of the transfer layer opposite to the transfer substrate side is constituted by the adhesive layer,
the adhesive layer comprises a polyolefin;
The transfer layer has a light transmittance of 20% or less at a wavelength of 330 nm.
Item 2. The transfer sheet according to Item 1, wherein the transfer layer is used in an application in which it is laminated with a molding resin containing polyolefin.
Item 3. The transfer sheet according to Item 1 or 2, wherein the polyolefin contained in the adhesive layer is a thermoplastic elastomer resin.
Item 4. The transfer sheet according to any one of Items 1 to 3, wherein the ultraviolet absorbing layer contains at least one of an ultraviolet absorber and a colorant.
Item 5. The transfer sheet according to any one of Items 1 to 4, wherein the ultraviolet absorbing layer has a first ultraviolet absorbing layer containing an ultraviolet absorber and a second ultraviolet absorbing layer containing a colorant.
Item 6. The transfer sheet according to Item 5, wherein the first ultraviolet absorbing layer is located closer to the transfer substrate than the second ultraviolet absorbing layer.
Item 7. The transfer sheet according to any one of Items 1 to 6, wherein the transfer layer further includes a protective layer on the transfer substrate side of the transfer layer.
Item 8. The transfer sheet according to any one of Items 1 to 7, further comprising a release layer between the transfer layer and the transfer substrate.
Item 9. A decorated resin molded product with a transfer substrate, in which at least a molded resin layer, a transfer layer, and a transfer substrate are laminated in this order,
the transfer layer includes an ultraviolet absorbing layer and an adhesive layer in this order from the transfer substrate side,
the surface of the transfer layer opposite to the transfer substrate side is constituted by the adhesive layer,
the adhesive layer comprises a polyolefin;
The transfer layer has a light transmittance of 20% or less at a wavelength of 330 nm.
Item 10. The resin molded article with a transfer substrate according to Item 9, wherein the molded resin layer contains polyolefin.
Item 11. A resin molded product having at least a molded resin layer and a transfer layer laminated in this order,
the transfer layer includes an ultraviolet absorbing layer and an adhesive layer in this order from the transfer substrate side,
the surface of the transfer layer opposite to the transfer substrate side is constituted by the adhesive layer,
the adhesive layer comprises a polyolefin;
The transfer layer has a light transmittance of 20% or less at a wavelength of 330 nm.
Item 12. The resin molded product according to Item 11, wherein the molded resin layer contains a polyolefin.

According to the present disclosure, it is possible to provide a transfer sheet comprising at least a transfer substrate and a transfer layer laminated together, which has high adhesion to a molded resin layer containing polyolefin and can suppress deterioration of the resin molded product due to ultraviolet rays. Furthermore, according to the present disclosure, it is also possible to provide a resin molded product with a transfer substrate that uses the transfer sheet, and a resin molded product from which the transfer substrate has been peeled off.

1 is a schematic diagram of a cross-sectional structure of one embodiment of a transfer sheet according to the present disclosure. 1 is a schematic diagram of a cross-sectional structure of one embodiment of a transfer sheet according to the present disclosure. 1 is a schematic diagram of a cross-sectional structure of one embodiment of a transfer sheet according to the present disclosure. 1 is a schematic diagram of a cross-sectional structure of one embodiment of a transfer sheet according to the present disclosure. 1 is a schematic diagram of a cross-sectional structure of one embodiment of a transfer sheet according to the present disclosure. 1 is a schematic diagram of a cross-sectional structure of one embodiment of a transfer sheet according to the present disclosure. 1 is a schematic diagram of a cross-sectional structure of one embodiment of a resin molded product with a transfer substrate according to the present disclosure. 1 is a schematic diagram of a cross-sectional structure of one embodiment of a resin molded product according to the present disclosure.

1. Transfer Sheet The transfer sheet of the present disclosure is a transfer sheet formed by laminating at least a transfer substrate and a transfer layer. The transfer layer comprises, in order from the transfer substrate side, a resin layer and an adhesive layer. The resin layer is adjacent to the adhesive layer. The surface of the transfer layer opposite the transfer substrate side is composed of an adhesive layer. The resin layer contains polyurethane, and the adhesive layer contains polyolefin. By having these configurations, the transfer sheet of the present disclosure has high adhesion to a molded resin layer containing polyolefin and suppresses deterioration of the resin molded product due to ultraviolet rays. The transfer sheet of the present disclosure will be described in detail below with reference to Figures 1 to 8.

In this specification, unless explicitly stated as "greater than or equal to" or "less than or equal to," numerical ranges indicated with "to" mean "greater than or equal to" or "less than or equal to." For example, 2 to 15 mm means 2 mm or greater and 15 mm or less. In the numerical ranges described in this disclosure in stages, the upper or lower limit value described in a certain numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, separately described upper and lower limits, upper and lower limits, or lower and lower limits may each be combined to form a numerical range. Furthermore, in the numerical ranges described in this disclosure, the upper or lower limit value described in a certain numerical range may be replaced with the value shown in the examples.

In addition, in this specification, "(meth)acrylate" means "acrylate or methacrylate," and other similar terms have the same meaning.

The transfer sheet of the present disclosure may not have a design layer, and may be transparent (allowing the molded resin layer to be seen through the transfer layer), for example.

In addition, in transfer sheets, "foil burrs" occur when, after the transfer layer has been laminated onto the molded resin layer, the transfer layer laminated onto the molded resin layer pulls on the portions of the transfer layer that do not need to be peeled off from the transfer substrate, causing the transfer layer to not be cut off at the edge of the surface to be transferred, and excess transfer layer to protrude from that edge and remain on the molded resin layer.

In transfer sheets, "blocking" occurs when the printed ink that makes up the transfer layer adheres to the transfer substrate when they are stored in an overlapping state, causing the transfer layer to peel off from the transfer substrate. Blocking is more likely to occur when the adhesive layer, which is the outermost layer of the transfer layer, is highly flexible. Blocking can be prevented by providing an anti-blocking layer (described below) on the side of the transfer substrate opposite the transfer layer.

Laminated Structure of Transfer Sheet The transfer sheet 10 of the present disclosure has at least a transfer substrate 1 and a transfer layer 8. In the transfer sheet 10 of the present disclosure, the surface of the transfer layer 8 opposite to the transfer substrate 1 side is composed of an adhesive layer 2.

The transfer layer 8 includes an adhesive layer 2 and an ultraviolet absorbing layer 3. The ultraviolet absorbing layer 3 may be a single layer or a multi-layer structure consisting of two or more layers. Figures 2 to 6 illustrate examples of the laminated structure of a transfer sheet in which the ultraviolet absorbing layer 3 includes a first ultraviolet absorbing layer 31 and a second ultraviolet absorbing layer 32. As described below, the ultraviolet absorbing layer 3 preferably includes a first ultraviolet absorbing layer containing an ultraviolet absorber and a second ultraviolet absorbing layer containing a colorant. The second ultraviolet absorbing layer containing a colorant can also function as a design layer that enhances the decorativeness of the transfer layer. Furthermore, in the transfer sheet of the present disclosure, the first ultraviolet absorbing layer 31 and the second ultraviolet absorbing layer 32 are preferably laminated in this order from the transfer substrate 1 side.

In addition to the adhesive layer 2 and the UV absorbing layer 3, the transfer layer 8 can further include at least one layer selected from the group consisting of a protective layer 4, a primer layer 5, and the like. It is preferable that the transfer layer 8 includes at least the protective layer 4. The adhesive layer 2 and the UV absorbing layer 3 may be adjacent to each other, or, as described below, a primer layer 5 or the like may be laminated between the adhesive layer 2 and the UV absorbing layer 3. For example, as described below, in the present disclosure, when the primer layer 5 contains a urethane resin (polyurethane), the adhesive layer 2 containing a polyolefin and the primer layer 5 are bonded with high adhesive strength, and further, the adhesive layer 2 can also exhibit high adhesiveness with the molded resin layer 9 containing a polyolefin.

In the transfer sheet 10 of the present disclosure, the transfer layer 8 is transferred to the molded resin layer 9 to form the resin molded product 20 of the present disclosure.

A release layer 11 may be provided between the transfer substrate 1 and the transfer layer 8, if necessary, for purposes such as improving the releasability between the transfer substrate 1 and the transfer layer 8. An anti-blocking layer 6 may also be provided on the side of the transfer substrate 1 opposite the transfer layer 8 to prevent blocking of the transfer sheet. In the transfer sheet 10 of the present disclosure, the transfer substrate 1, the release layer 11 (if provided as needed), and the anti-blocking layer 6 (if provided as needed) constitute a support. This support is peeled off and removed after the transfer layer 8 of the transfer sheet 10 is integrated with the molded resin layer 9.

The laminate structure of the transfer sheet of the present disclosure is:
a laminated structure in which a transfer substrate/an ultraviolet absorbing layer/an adhesive layer are laminated in this order;
a laminated structure in which a transfer substrate/protective layer/ultraviolet absorbing layer/adhesive layer are laminated in this order;
a laminated structure in which a transfer substrate/protective layer/ultraviolet absorbing layer/primer layer/adhesive layer are laminated in this order;
a laminated structure in which a transfer substrate/a release layer/a protective layer/an ultraviolet absorbing layer/a primer layer/an adhesive layer are laminated in this order;
a laminated structure in which an anti-blocking layer/transfer substrate/release layer/protective layer/ultraviolet absorbing layer/primer layer/adhesive layer are laminated in this order;
a laminated structure in which a transfer substrate/a first ultraviolet absorbing layer/a second ultraviolet absorbing layer/an adhesive layer are laminated in this order;
a laminated structure in which a transfer substrate/protective layer/first ultraviolet absorbing layer/second ultraviolet absorbing layer/adhesive layer are laminated in this order;
a laminated structure in which a transfer substrate/protective layer/first ultraviolet absorbing layer/second ultraviolet absorbing layer/primer layer/adhesive layer are laminated in this order;
a laminated structure in which a transfer substrate/a release layer/a protective layer/a first ultraviolet absorbing layer/a second ultraviolet absorbing layer/a primer layer/an adhesive layer are laminated in this order;
a laminated structure in which an anti-blocking layer/transfer substrate/release layer/protective layer/first ultraviolet absorbing layer/second ultraviolet absorbing layer/primer layer/adhesive layer are laminated in this order;
Examples include:

FIG. 1 shows a schematic diagram of the cross-sectional structure of one embodiment of the laminate structure of the transfer sheet of the present disclosure, in which a transfer substrate/ultraviolet absorbing layer/adhesive layer are laminated in this order.
FIG. 2 shows a schematic diagram of the cross-sectional structure of one embodiment of the laminated structure of the transfer sheet of the present disclosure, in which a transfer substrate/first ultraviolet absorbing layer/second ultraviolet absorbing layer/adhesive layer are laminated in this order.
FIG. 3 shows a schematic diagram of the cross-sectional structure of one embodiment of the laminated structure of the transfer sheet of the present disclosure, in which a transfer substrate/protective layer/first ultraviolet absorbing layer/second ultraviolet absorbing layer/adhesive layer are laminated in this order.
FIG. 4 shows a schematic diagram of the cross-sectional structure of one embodiment of the laminated structure of the transfer sheet of the present disclosure, in which a transfer substrate/protective layer/first ultraviolet absorbing layer/second ultraviolet absorbing layer/primer layer/adhesive layer are laminated in this order.
FIG. 5 shows a schematic diagram of the cross-sectional structure of one embodiment of the laminated structure of the transfer sheet of the present disclosure, in which a transfer substrate/release layer/protective layer/first ultraviolet absorbing layer/second ultraviolet absorbing layer/primer layer/adhesive layer are laminated in this order.
FIG. 6 shows a schematic diagram of the cross-sectional structure of one embodiment of the laminated structure of the transfer sheet of the present disclosure, in which an anti-blocking layer/transfer substrate/release layer/protective layer/first ultraviolet absorbing layer/second ultraviolet absorbing layer/primer layer/adhesive layer are laminated in this order.
The "/" indicates a separation between layers.

In the transfer sheet 10, the ratio of the total thickness of the transfer substrate 1, UV absorbing layer 3 (single layer or multiple layers), adhesive layer 2, optional protective layer 4, optional primer layer 5, optional release layer 11, and optional anti-blocking layer 6 to the thickness (total thickness) of the laminate constituting the transfer sheet 10 is, for example, 80% or more, preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more.

As a specific example, when the transfer sheet 10 of the present disclosure is a laminate including a transfer substrate 1, an ultraviolet absorbing layer 3 (single layer or multiple layers), an adhesive layer 2, a protective layer 4, a primer layer 5, and a release layer 11, the ratio of the total thickness of these layers to the thickness (total thickness) of the laminate constituting the transfer sheet 10 is, for example, 80% or more, preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. Also, when the transfer sheet 10 of the present disclosure is a laminate including a transfer substrate 1, an ultraviolet absorbing layer 3 (single layer or multiple layers), an adhesive layer 2, a protective layer 4, a primer layer 5, a release layer 11, and an anti-blocking layer 6, the ratio of the total thickness of these layers to the thickness (total thickness) of the laminate constituting the transfer sheet 10 can be, for example, 80% or more, preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more.

Layers forming the transfer sheet [support]
The transfer sheet of the present disclosure has a transfer substrate 1 as a support. The support further has a release layer 11 and an anti-blocking layer 6 as needed. An adhesive layer 2 and an ultraviolet absorbing layer 3 formed on the transfer substrate 1 constitute a transfer layer 8. Furthermore, a protective layer 4, a primer layer 5, and the like, which are provided as needed, also constitute the transfer layer 8. In the present disclosure, after the transfer sheet and the molding resin are integrally molded, the interface between the support and the transfer layer 8 is peeled off to obtain a resin molded product.

(Transfer substrate 1)
In the present disclosure, the transfer substrate 1 is used as a support that serves as a support member in the transfer sheet. The transfer substrate 1 used in the present disclosure is selected in consideration of its suitability for vacuum forming, and a resin sheet made of a thermoplastic resin is typically used. Examples of such thermoplastic resins include polyester; acrylic resin; polyolefins such as polypropylene and polyethylene; polycarbonate; acrylonitrile-butadiene-styrene resin (ABS resin); and vinyl chloride resin.

In the present disclosure, it is preferable to use a polyester film as the transfer substrate 1. The polyester that constitutes the polyester sheet refers to a polymer containing ester groups obtained by polycondensation of a polycarboxylic acid and a polyhydric alcohol. Preferred examples include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN), with polyethylene terephthalate (PET) being particularly preferred in terms of its heat resistance and dimensional stability.

When a release layer 11 (described later) is provided, the transfer substrate 1 may be subjected to a physical or chemical surface treatment, such as an oxidation method or a roughening method, on one or both sides, as desired, to improve adhesion to the release layer 11. Examples of oxidation methods include corona discharge treatment, chromium oxidation treatment, flame treatment, hot air treatment, and ozone/ultraviolet treatment. Examples of roughening methods include sandblasting and solvent treatment. These surface treatments are selected appropriately depending on the type of transfer substrate 1, but corona discharge treatment is generally preferred in terms of effectiveness and operability. The transfer substrate 1 may also be subjected to treatments such as the formation of an easy-adhesion layer to strengthen interlayer adhesion between the transfer substrate 1 and the layer to be formed thereon. When using a commercially available polyester sheet, the commercially available product may be one that has already been surface-treated as described above or one that has an easy-adhesion layer formed thereon.

The thickness of the transfer substrate 1 is preferably 25 μm or more, more preferably 38 μm or more, even more preferably 50 μm or more, and preferably 188 μm or less, more preferably 100 μm or less. The preferred range for the thickness of the transfer substrate 1 is approximately 38 μm or more and 188 μm or less, even more preferably 50 μm or more and 100 μm or less. The transfer substrate 1 can be a single-layer sheet of these resins, or a multi-layer sheet made of the same or different resins.

(Release layer 11)
The release layer 11 is provided, as necessary, on the surface of the transfer substrate 1 on which the transfer layer 8 is laminated, for the purpose of improving the releasability between the transfer substrate 1 and the transfer layer 8. The release layer 11 may be a solid release layer that covers the entire surface (solid on the entire surface), or may be provided on a part of the surface. Usually, a solid release layer is preferred in consideration of releasability.

The release layer 11 can be formed using a resin composition containing a mixture of thermoplastic resins such as silicone resin, fluororesin, acrylic resin (including, for example, acrylic-melamine resin), polyester, polyolefin, polystyrene resin, polyurethane, cellulose resin, vinyl chloride-vinyl acetate copolymer, and soluble nitrocellulose; copolymers of the monomers that form these thermoplastic resins; ionizing radiation curable resins; or resins modified with (meth)acrylic acid or urethane. Among these, acrylic resin, polyester, polyolefin, polystyrene resin, copolymers of the monomers that form these resins, and urethane-modified versions of these are preferred. More specific examples include acrylic-melamine resin alone, compositions containing acrylic-melamine resin, resin compositions mixed with urethane-modified polyester and ethylene/acrylic acid copolymer, and resin compositions mixed with an emulsion of acrylic resin and styrene/acrylic copolymer. Of these, it is particularly preferred to form the release layer 11 using an ionizing radiation curable resin composition.

(ionizing radiation curable resin)
The ionizing radiation curable resin used to form the release layer 11 is a resin that crosslinks and hardens when irradiated with ionizing radiation, and specifically includes a suitable mixture of at least one of prepolymers, oligomers, and monomers having a polymerizable unsaturated bond or an epoxy group in the molecule. Here, the ionizing radiation is as described in the section [Protective Layer 4] below.

The monomer used as the ionizing radiation curable resin is preferably a (meth)acrylate monomer having a radically polymerizable unsaturated group in the molecule, and particularly preferably a polyfunctional (meth)acrylate monomer. The polyfunctional (meth)acrylate monomer may be a (meth)acrylate monomer having two or more (difunctional or more), preferably three or more (trifunctional or more), polymerizable unsaturated bonds in the molecule. Specific examples of polyfunctional (meth)acrylate monomers include ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, hydroxypivalic acid neopentyl glycol di(meth)acrylate, dicyclopentanyl di(meth)acrylate, caprolactone-modified dicyclopentenyl di(meth)acrylate, ethylene oxide-modified phosphate di(meth)acrylate, allylated cyclohexyl di(meth)acrylate, isocyanurate di(meth)acrylate, and trimethylol. Examples of suitable monomers include propane tri(meth)acrylate, ethylene oxide-modified trimethylolpropane tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, propionic acid-modified dipentaerythritol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propylene oxide-modified trimethylolpropane tri(meth)acrylate, tris(acryloxyethyl)isocyanurate, propionic acid-modified dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ethylene oxide-modified dipentaerythritol hexa(meth)acrylate, and caprolactone-modified dipentaerythritol hexa(meth)acrylate. These monomers may be used alone or in combination of two or more.

Furthermore, the oligomer used as the ionizing radiation curable resin is preferably a (meth)acrylate oligomer having a radically polymerizable unsaturated group in the molecule, and particularly preferably a polyfunctional (meth)acrylate oligomer having two or more polymerizable unsaturated bonds (bifunctional or higher) in the molecule. Examples of polyfunctional (meth)acrylate oligomers include polycarbonate (meth)acrylate, acrylic silicone (meth)acrylate, urethane (meth)acrylate, epoxy (meth)acrylate, polyester (meth)acrylate, polyether (meth)acrylate, polybutadiene (meth)acrylate, silicone (meth)acrylate, and oligomers having a cationically polymerizable functional group in the molecule (e.g., novolac epoxy resin, bisphenol epoxy resin, aliphatic vinyl ether, aromatic vinyl ether, etc.). Here, the polycarbonate (meth)acrylate is not particularly limited as long as it has a carbonate bond in the polymer main chain and a (meth)acrylate group at the end or side chain. For example, it can be obtained by esterifying a polycarbonate polyol with (meth)acrylic acid. The polycarbonate (meth)acrylate may be, for example, a urethane (meth)acrylate having a polycarbonate skeleton. The urethane (meth)acrylate having a polycarbonate skeleton can be obtained, for example, by reacting a polycarbonate polyol with a polyvalent isocyanate compound and a hydroxy (meth)acrylate. The acrylic silicone (meth)acrylate can be obtained by radical copolymerization of a silicone macromonomer with a (meth)acrylate monomer. The urethane (meth)acrylate can be obtained, for example, by esterifying a polyurethane oligomer obtained by reacting a polyether polyol, polyester polyol, or caprolactone polyol with a polyisocyanate compound with (meth)acrylic acid. Epoxy (meth)acrylates can be obtained, for example, by reacting (meth)acrylic acid with the oxirane ring of a relatively low-molecular-weight bisphenol-type epoxy resin or novolac-type epoxy resin to esterify it. Carboxyl-modified epoxy (meth)acrylates, in which the epoxy (meth)acrylates are partially modified with dibasic carboxylic acid anhydrides, can also be used. Polyester (meth)acrylates can be obtained, for example, by esterifying the hydroxyl groups of a polyester oligomer having hydroxyl groups at both ends, obtained by condensation of a polycarboxylic acid and a polyhydric alcohol, with (meth)acrylic acid, or by esterifying the terminal hydroxyl groups of an oligomer obtained by adding an alkylene oxide to a polycarboxylic acid with (meth)acrylic acid. Polyether (meth)acrylates can be obtained by esterifying the hydroxyl groups of a polyether polyol with (meth)acrylic acid. Polybutadiene (meth)acrylates can be obtained by adding (meth)acrylic acid to the side chain of a polybutadiene oligomer. Silicone (meth)acrylates can be obtained by adding (meth)acrylic acid to the end or side chain of a silicone having a polysiloxane bond in its main chain. Among these, polycarbonate (meth)acrylate and urethane (meth)acrylate are particularly preferred as polyfunctional (meth)acrylate oligomers. These oligomers may be used alone or in combination of two or more.

When forming the release layer 11 using an ionizing radiation curable resin, the release layer 11 is formed, for example, by preparing an ionizing radiation curable resin composition containing fine particles and an ionizing radiation curable resin, applying the composition, and curing it. The viscosity of the ionizing radiation curable resin composition may be any viscosity that allows the formation of an uncured resin layer using the application method described below.

In the present disclosure, the prepared coating solution is applied to the above-mentioned thickness by a known method such as gravure coating, bar coating, roll coating, reverse roll coating, or comma coating, preferably gravure coating, to form an uncured resin layer.

The uncured resin layer thus formed is then irradiated with ionizing radiation such as electron beams or ultraviolet rays to cure the uncured resin layer and form the release layer 11. When using electron beams as the ionizing radiation, the acceleration voltage can be selected appropriately depending on the resin used and the layer thickness, but typically is 70 kV or more and 300 kV or less.

In addition, since the higher the acceleration voltage is during electron beam irradiation, the greater the penetration ability, when a resin that is easily degraded by electron beam irradiation is used below the release layer 11, the acceleration voltage should be selected so that the penetration depth of the electron beam is substantially equal to the thickness of the release layer 11. This prevents excessive electron beam irradiation of layers located below the release layer 11, minimizing the degradation of each layer due to excess electron beams.

The irradiation dose is preferably an amount at which the crosslinking density of the release layer 11 saturates, and is typically 5 kGy or more (0.5 Mrad or more), preferably 10 kGy or more (1 Mrad or more), and typically 300 kGy or less (30 Mrad or less), preferably 50 kGy or less (5 Mrad or less). The irradiation dose is typically selected from the range of 5 kGy to 300 kGy (0.5 Mrad to 30 Mrad), preferably 10 kGy to 50 kGy (1 Mrad to 5 Mrad).

Furthermore, there are no particular limitations on the electron beam source, and various electron beam accelerators can be used, such as Cockcroft-Walton type, Van de Graaf type, resonant transformer type, insulating core transformer type, linear type, dynamitron type, and high frequency type.

When ultraviolet light is used as the ionizing radiation, light containing ultraviolet light with a wavelength of 190 nm or more and 380 nm or less should be emitted. The ultraviolet light source is not particularly limited, but examples include high-pressure mercury lamps, low-pressure mercury lamps, metal halide lamps, carbon arc lamps, and ultraviolet light-emitting diodes (LED-UV).

The thickness of the release layer 11 is preferably 0.01 μm or more, more preferably 0.05 μm or more, and preferably 5 μm or less, more preferably 3 μm or less. The preferred range for the thickness of the release layer 11 is 0.01 μm or more, preferably 5 μm or less, more preferably 0.05 μm or more and 3 μm or less.

(Anti-blocking layer 6)
In the transfer sheet of the present disclosure, the anti-blocking layer 6 is a layer that is provided, as necessary, on the side of the transfer substrate 1 opposite the transfer layer 8 in order to effectively suppress blocking in the transfer sheet. The anti-blocking layer 6 is preferably formed from a resin composition containing particles and a thermoplastic resin.

Thermoplastic resins are not particularly limited, but examples include acrylic resins such as polymethyl (meth)acrylate; polyolefins such as polypropylene and polyethylene; polycarbonate; vinyl chloride resins such as polyvinyl chloride and vinyl chloride-vinyl acetate copolymer; polyester; acrylonitrile-butadiene-styrene resin (ABS resin); acrylonitrile-styrene-acrylic ester resin; and the like. Thermoplastic resins may be used singly or in combination of two or more.

The particles are not particularly limited, and any known anti-blocking agent can be used. Examples of particles include inorganic particles and resin particles.

The inorganic particles are not particularly limited as long as they are particles formed from an inorganic compound, and examples include silica particles, calcium carbonate particles, barium sulfate particles, alumina particles, and glass balloon particles. Of these, silica particles are preferred. One type of inorganic particle may be used alone, or two or more types may be used in combination.

The resin particles are not particularly limited as long as they are particles formed from resin, and examples include urethane beads, nylon beads, acrylic beads, silicone beads, styrene beads, melamine beads, urethane acrylic beads, polyester beads, and polyethylene beads. One type of resin particle may be used alone, or two or more types may be used in combination.

The particle diameter of the particles is, for example, 0.5 μm or more, preferably 1 μm or more, and preferably 20 μm or less, more preferably 10 μm or less. A preferred range for the particle diameter of the particles is preferably 0.5 μm or more and 20 μm or less, more preferably 1 μm or more and 10 μm or less. In this disclosure, the particle diameter of the particles is the average particle diameter of 30 random particles when the cross section of the anti-blocking layer is observed with a scanning electron microscope (SEM).

The particle content of the anti-blocking layer 6 is not particularly limited, but is preferably 1% by mass or more, more preferably 3% by mass or more, and is preferably 15% by mass or less, more preferably 10% by mass or less. The preferred range for the particle content of the anti-blocking layer 6 is preferably 1% by mass or more and 15% by mass or less, more preferably 3% by mass or more and 10% by mass or less.

The thickness of the anti-blocking layer 6 is not particularly limited, but is, for example, 10 μm or less, preferably 5 μm or less, and preferably 0.5 μm or more, more preferably 1 μm or more. A preferred range for the thickness of the anti-blocking layer 6 is, for example, 0.5 μm or more and 10 μm or less, more preferably 1 μm or more and 5 μm or less. In this disclosure, the thickness of the anti-blocking layer 6 refers to the thickness in the areas where no protrusions formed by particles exist.

The particle diameter of the particles is preferably larger than the thickness of the anti-blocking layer 6. For example, the particle diameter of the particles is preferably 1.1 times or more, more preferably 1.3 times or more, and preferably 5 times or less, and more preferably 3 times or less, the thickness of the anti-blocking layer 6. For example, the particle diameter of the particles is preferably 1.1 times or more and 5 times or less, and more preferably 1.3 times or more and 3 times or less, the thickness of the anti-blocking layer 6.

[Transfer layer 8]
In the transfer sheet of the present disclosure, at least an ultraviolet absorbing layer 3 and an adhesive layer 2 formed on a support constitute a transfer layer 8. In the transfer sheet of the present disclosure, the transfer layer 8 preferably includes at least one layer selected from the group consisting of a protective layer 4, a primer layer 5, and the like, in addition to the ultraviolet absorbing layer 3 and the adhesive layer 2. In the present disclosure, after the transfer sheet and the molding resin are integrally molded, the interface between the support and the transfer layer 8 is peeled off, and a resin molded product is obtained in which the transfer layer 8 of the transfer sheet is transferred to the molding resin layer 9.

In the transfer sheet of the present disclosure, the transfer layer 8 has a light transmittance of 20% or less at a wavelength of 330 nm. In the transfer sheet of the present disclosure, the light transmittance of the transfer layer 8 at the specific wavelength of 330 nm is controlled to 20% or less, which can effectively suppress ultraviolet light-induced deterioration of resin molded products containing polyolefin.

The light transmittance of the transfer layer 8 at a wavelength of 330 nm needs only to be 20% or less. However, from the perspective of more optimally exerting the effects of the presently disclosed invention, the light transmittance is preferably 15% or less, more preferably 10% or less, and even more preferably 5% or less. The lower limit is, for example, 0% or 1%, and preferred ranges include 0-20%, 0-10%, 0-5%, 1-20%, 1-10%, and 1-5%. The light transmittance of the transfer layer 8 at a wavelength of 330 nm is a value measured by the following method.

<Light transmittance at a wavelength of 330 nm>
The light transmittance is determined by measuring the spectral transmittance in the wavelength range of 300 nm to 800 nm using an ultraviolet-visible spectrophotometer, and the value at a wavelength of 330 nm in the obtained spectral transmittance spectrum is used. After measuring the spectral transmittance of the transfer sheet, the transfer layer is removed from the transfer sheet, and the spectral transmittance of the support alone is measured. The spectral transmittance of the transfer layer is determined by subtracting the spectral transmittance of the support alone from the spectral transmittance of the transfer sheet. A D65 light source is used.
Spectral transmittance of transfer sheet ÷ Spectral transmittance of support × 100% = Spectral transmittance of transfer layer

In the transfer sheet of the present disclosure, it is important to control the light transmittance of the transfer layer 8 at a specific wavelength of 330 nm to 20% or less in order to effectively suppress UV degradation of resin molded products containing polyolefin. Therefore, it is not necessary to control the light transmittance of the transfer layer 8 at other wavelengths, such as 380 nm and 340 nm, to a specific value or less. For example, in the transfer sheet of the present disclosure, the light transmittance of the transfer layer 8 at a wavelength of 380 nm may be greater than 30%, or may be 31% or more, 32% or more, 35% or more, 40% or more, etc. The upper limit of the light transmittance of the transfer layer 8 at a wavelength of 380 nm is, for example, 60%. Furthermore, in the transfer sheet of the present disclosure, the light transmittance of the transfer layer 8 at a wavelength of 340 nm may be greater than 10%, or may be 11% or more, 12% or more, 15% or more, 20% or more, etc. The upper limit of the light transmittance of the transfer layer 8 at a wavelength of 340 nm is, for example, 50%. The light transmittance of the transfer layer 8 at a wavelength of 380 nm or 340 nm is a value measured by changing the measurement wavelength from 330 nm to 380 nm or 340 nm using the measurement method described above in <Light transmittance at a wavelength of 330 nm>.

Each layer of the transfer layer 8 is described in detail below.

(Adhesive layer 2)
The adhesive layer 2 is a layer that constitutes the surface of the transfer layer 8 opposite to the transfer substrate 1 side, for the purpose of improving the adhesion between the transfer layer 8 and the molded resin layer 9. Therefore, when the transfer sheet of the present disclosure is laminated with the molded resin layer 9, the adhesive layer 2 becomes the layer that comes into contact with the molded resin layer 9.

In the present disclosure, the adhesive layer 2 is characterized by containing a polyolefin. As described above, the transfer sheet of the present disclosure has the adhesive layer 2 formed from an adhesive containing a polyolefin, and is able to exhibit high adhesion with the molded resin layer 9, which contains a polyolefin such as polypropylene.

The polyolefin contained in the adhesive layer 2 is not particularly limited as long as it exhibits high adhesion to the UV-absorbing layer 3 and the molded resin layer 9 (or, if a primer layer 5 is present between the UV-absorbing layer 3 and the adhesive layer 2, high adhesion to the primer layer 5 and the molded resin layer 9). Preferred examples include unmodified polyolefins, as well as modified polyolefins such as acid-modified polyolefins, chlorinated polyolefins, and acrylic-modified polyolefins. For example, acid-modified polyolefins are polymers modified by block or graft polymerization of polyolefins with an acid component. Chlorinated polyolefins are olefin resins in which some of the hydrogen atoms have been replaced with chlorine atoms. Acrylic-modified polyolefins are polymers modified by block or graft polymerization of acrylic resin and olefin resin. Furthermore, the modified polyolefin is preferably a thermoplastic elastomer using polystyrene for the hard segment and any polyolefin for the soft segment (styrene-butadiene-styrene (SBS resin), styrene-isoprene-styrene (SIS resin)), or a hydrogenated thermoplastic elastomer resin such as styrene-ethylene-butylene-styrene (SEBS resin) or styrene-ethylene-propylene-styrene (SEPS resin) obtained by hydrogenating these resins. These resins may be further acid-modified or chlorinated. The adhesive layer 2 may contain only one type of polyolefin, or two or more types.

Specific examples of polyolefins include polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; ethylene-α-olefin copolymers; polypropylenes such as homopolypropylene, block copolymers of polypropylene (e.g., block copolymers of propylene and ethylene), and random copolymers of polypropylene (e.g., random copolymers of propylene and ethylene); propylene-α-olefin copolymers; and ethylene-butene-propylene terpolymers. Of these, polypropylene is preferred. When polyolefins are copolymers, they may be block copolymers or random copolymers.

Modified polyolefins include copolymers of these polyolefins with polar molecules such as acrylic acid and methacrylic acid. Acid-modified polyolefins include acid-modified polypropylene. Chlorinated polyolefins include chlorinated polypropylene. Acrylic-modified polyolefins include acrylic-modified polypropylene.

Examples of acid components used for acid modification include carboxylic acids or anhydrides such as maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, and itaconic anhydride.

From the perspective of more optimally achieving the effects of the presently disclosed invention, the main component of the resin contained in adhesive layer 2 is preferably polyolefin. "Main component" means a resin that accounts for, for example, 50% by mass or more of the resin contained in the adhesive layer. The polyolefin content of the resin contained in adhesive layer 2 is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, and even more preferably 100% by mass.

Adhesive layer 2 may contain a resin other than polyolefin, as long as it does not impair the effects of the present disclosure. When adhesive layer 2 contains a resin other than polyolefin, the resin is not particularly limited, as long as it does not impair the effects of the present disclosure, and may be, for example, a thermoplastic resin or a thermosetting resin. Examples of thermoplastic resins include vinyl chloride-vinyl acetate copolymer, acrylic resin, thermoplastic urethane resin, thermoplastic polyester resin, polyamide, and rubber resin. When adhesive layer 2 contains a resin other than polyolefin, the resin other than polyolefin contained in adhesive layer 2 may be only one type, or two or more types. As mentioned above, even when adhesive layer 2 contains a resin other than polyolefin, it is preferable that the main component of the resin contained in adhesive layer 2 is polyolefin.

The adhesive layer 2 may also contain various additives. Examples of additives include inorganic particles, organic particles, pigments, dyes, UV absorbers, antioxidants, and light stabilizers.

The adhesive layer 2 can be formed from an adhesive layer-forming resin composition. The adhesive layer-forming resin composition can contain a solvent in addition to polyolefin. Any solvent capable of forming the adhesive layer 2 is acceptable; however, if the primer layer 5 contains a urethane resin, a solvent with high affinity for the urethane resin and capable of dissolving the urethane resin is preferred. In other words, when forming the adhesive layer 2 on the primer layer 5, the adhesive layer-forming resin composition applied to the surface of the primer layer 5 dissolves the surface portion of the UV-absorbing layer 3, and the adhesive layer 2 is cured. This facilitates adhesion between the primer layer 5 and the adhesive layer 2. Examples of preferred solvents included in the adhesive layer-forming resin composition include methylcyclohexane, toluene, xylene, and hexane. Among these, methylcyclohexane and toluene are more preferred. The adhesive layer-forming resin composition may contain only one type of solvent, or two or more types.

If the adhesive layer-forming resin composition contains a solvent, trace amounts of solvent may remain in the adhesive layer 2 formed from the adhesive layer-forming resin composition. If solvent remains in the adhesive layer 2 of the transfer sheet 10, the resin molded product 20 using the transfer sheet 10 will also contain the solvent, which may be undesirable from the perspective of VOC (volatile organic compound) regulations. For example, it is desirable not to use volatile organic compounds such as benzene, toluene, xylene, ethylbenzene, styrene, formaldehyde, acetaldehyde, and acrolein as solvents for the adhesive layer-forming resin composition that forms the adhesive layer 2. From this perspective, methylcyclohexane is particularly preferred as a solvent for the adhesive layer-forming resin composition used to form the adhesive layer 2.

In view of VOC (volatile organic compound) regulations, the toluene content in the transfer sheet 10 of the present disclosure is preferably 0.5 mg/ ^m2 or less, more preferably 0.2 mg/ ^m2 or less, with the lower limit being 0.0 mg/ ^m2 . The toluene content in the transfer sheet is measured as follows.

<Measurement of toluene content in transfer sheet>
The toluene content of the transfer sheet can be measured using gas chromatography. In this method, the transfer sheet (size: 50 x 100 mm) after production is placed in a container (20 mL headspace vial) and sealed with a crimp cap using a crimper. The toluene content (mg/ ^m2 ) of this is measured using a gas chromatograph.

The adhesive layer 2 is formed using an adhesive layer-forming resin composition by a conventional coating method such as gravure coating, gravure reverse coating, gravure offset coating, spinner coating, roll coating, reverse roll coating, kiss coating, wheel coating, dip coating, solid coating by silk screen, wire bar coating, flow coating, comma coating, flow coating, brush coating, or spray coating.

(Ultraviolet absorbing layer 3)
The transfer sheet of the present disclosure is provided with an ultraviolet absorbing layer 3, and the light transmittance of the transfer layer 8 at a wavelength of 330 nm is controlled to 20% or less, so that deterioration of resin molded products containing polyolefins due to ultraviolet rays can be effectively suppressed.

The ultraviolet absorbing layer 3 may be a single layer or a multi-layer structure consisting of two or more layers. Figures 2 to 6 show examples of the laminated structure of a transfer sheet in which the ultraviolet absorbing layer 3 includes a first ultraviolet absorbing layer 31 and a second ultraviolet absorbing layer 32.

The ultraviolet absorbing layer 3 preferably contains at least one of an ultraviolet absorber and a colorant. In the present disclosure, the colorant in the ultraviolet absorbing layer 3 preferably contains one that exhibits ultraviolet absorbing properties. As described below, the ultraviolet absorbing layer 3 preferably has a first ultraviolet absorbing layer containing an ultraviolet absorber and a second ultraviolet absorbing layer containing a colorant. The second ultraviolet absorbing layer containing a colorant can also function as a design layer that enhances the decorativeness of the transfer layer. In the transfer sheet of the present disclosure, the first ultraviolet absorbing layer 31 and the second ultraviolet absorbing layer 32 are preferably laminated in this order from the transfer substrate 1 side.

Examples of UV absorbers include organic and inorganic UV absorbers. From the perspective of more optimally achieving the effects of the present invention, examples of organic UV absorbers include benzophenone-based UV absorbers, triazine-based UV absorbers, benzotriazole-based UV absorbers, benzoxazine-based UV absorbers, cyanoacrylate-based UV absorbers, and salicylic acid-based UV absorbers. Examples of inorganic UV absorbers include titanium dioxide, cerium oxide, and zinc oxide. The UV absorbing layer 3 may contain only one type of UV absorber, or two or more types.

From the perspective of more optimally exerting the effects of the presently disclosed invention, the content of the ultraviolet absorber contained in the ultraviolet absorbing layer 3 is preferably 0.5% by mass or more, more preferably 1% by mass or more, and even more preferably 3% by mass or more, and is preferably 15% by mass or less, more preferably 12% by mass or less, and even more preferably 10% by mass or less. Preferred ranges include approximately 0.5 to 15% by mass, approximately 0.5 to 12% by mass, approximately 0.5 to 10% by mass, approximately 1 to 15% by mass, approximately 1 to 12% by mass, approximately 1 to 10% by mass, approximately 3 to 15% by mass, approximately 3 to 12% by mass, and approximately 3 to 10% by mass.

In addition, from the viewpoint of more optimally achieving the effects of the present invention, the colorant contained in the ultraviolet absorbing layer 3 is preferably a pigment or dye that exhibits the function of absorbing ultraviolet light. Specific examples of pigments include azo pigments such as condensed azo, phthalocyanine pigments such as phthalocyanine blue, threne pigments such as anthraquinone and perylene, condensed polycyclic pigments such as quinacridone, titanium pigments such as titanium oxide, iron oxide pigments such as red iron oxide, chromate pigments such as yellow lead, aluminate pigments such as cobalt blue, and metal oxides such as carbon black and aluminum oxide. Specific examples of dyes include perylene dyes, coumarin dyes, thioindigo dyes, anthraquinone dyes, thioxanthone dyes, ferrocyanides, quinoline dyes, and isoindolinone dyes. The ultraviolet absorbing layer 3 may contain only one type of dye, or two or more types of dyes.

From the perspective of more optimally exerting the effects of the presently disclosed invention, the content of the colorant contained in the ultraviolet absorbing layer 3 is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, and is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. Preferred ranges include approximately 1 to 50% by mass, approximately 1 to 40% by mass, approximately 1 to 30% by mass, approximately 5 to 50% by mass, approximately 5 to 40% by mass, approximately 5 to 30% by mass, approximately 10 to 50% by mass, approximately 10 to 40% by mass, and approximately 10 to 30% by mass.

The UV-absorbing layer 3 can be formed, for example, from a resin composition containing at least one of a UV absorber and a colorant, and a resin. The resin contained in the resin composition is not particularly limited, but examples include polyol and/or its cured product, acrylic resin, (meth)acrylic-urethane copolymer resin, polyester, butyral resin, styrene resin, polyester, polyurethane, chlorinated polyolefin, vinyl chloride-vinyl acetate copolymer resin, polyvinyl butyral resin, alkyd resin, petroleum resin, ketone resin, epoxy resin, melamine resin, fluororesin, silicone resin, cellulose derivative, rubber resin, etc. These resins may be used alone or in combination of two or more.

For example, when the ultraviolet absorbing layer 3 contains an ultraviolet absorber (for example, in the case of a first ultraviolet absorbing layer 31 containing an ultraviolet absorber), the resin in question is preferably polyol and/or its cured product, polyurethane, acrylic resin, (meth)acrylic-urethane copolymer resin, polyester, butyral resin, etc. Among these resins, polyol and/or its cured product, polyurethane, acrylic resin, and acrylic urethane resin are preferred.

When the UV absorbing layer 3 contains a UV absorber (for example, when the first UV absorbing layer 31 contains a UV absorber), the layer is preferably formed from a resin composition containing a polyol and polyurethane. The polyol may be any compound having two or more hydroxyl groups in the molecule. Specific examples include polyester polyol, polyethylene glycol, polypropylene glycol, acrylic polyol, polyether polyol, etc., with acrylic polyol being preferred.

When polyol and polyurethane are used, the mass ratio thereof (polyol/polyurethane) is preferably 5/5 or more, preferably 7/3 or more, or preferably 9.5/0.5 or less, more preferably 9/1 or less. The preferred range for the mass ratio (polyol/polyurethane) is 5/5 or more and 9.5/0.5 or less, more preferably 7/3 or more and 9/1 or less.

An example of a cured product of polyol is polyurethane. Polyurethanes that use polyol (polyhydric alcohol) as the base component and isocyanate as the crosslinking agent (curing agent) can be used.

Specific examples of isocyanates include polyvalent isocyanates having two or more isocyanate groups in the molecule; aromatic isocyanates such as 4,4-diphenylmethane diisocyanate; and aliphatic (or alicyclic) isocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate, and hydrogenated diphenylmethane diisocyanate. When an isocyanate is used as a curing agent, the content of the isocyanate in the resin composition for forming the ultraviolet absorbing layer is not particularly limited. However, from the viewpoints of adhesion and printability, it is preferably 3 parts by mass or more, and preferably 45 parts by mass or less, and more preferably 25 parts by mass or less, per 100 parts by mass of the polyol. The content of the isocyanate in the resin composition for forming the ultraviolet absorbing layer is preferably 3 parts by mass or more and 45 parts by mass or less, and more preferably 3 parts by mass or more and 25 parts by mass or less, per 100 parts by mass of the polyol.

Of the above polyurethanes, from the viewpoint of improving adhesion after crosslinking, a combination of an acrylic polyol or polyester polyol as the polyol and hexamethylene diisocyanate or 4,4-diphenylmethane diisocyanate as the crosslinking agent is preferred; and a combination of an acrylic polyol and hexamethylene diisocyanate is even more preferred.

The acrylic resin is not particularly limited, but examples include a homopolymer of a (meth)acrylic acid ester, a copolymer of two or more different (meth)acrylic acid ester monomers, or a copolymer of a (meth)acrylic acid ester and another monomer. More specific examples of the (meth)acrylic resin include (meth)acrylic acid esters such as polymethyl(meth)acrylate, polyethyl(meth)acrylate, polypropyl(meth)acrylate, polybutyl(meth)acrylate, methyl(meth)acrylate-butyl(meth)acrylate copolymer, ethyl(meth)acrylate-butyl(meth)acrylate copolymer, ethylene-methyl(meth)acrylate copolymer, and styrene-methyl(meth)acrylate copolymer.

The acrylic urethane resin is not particularly limited, but examples thereof include acrylic-urethane block copolymers, and more specifically, acrylic-polyester urethane block copolymers. The ratio of acrylic to urethane in the acrylic-urethane block copolymer is not particularly limited, but examples include an acrylic/urethane ratio (mass ratio) of preferably 9/1 or less, more preferably 8/2 or less, and also preferably 1/9 or more, more preferably 2/8 or more. The preferred range for the acrylic/urethane ratio (mass ratio) is 1/9 or more and 9/1 or less, more preferably 2/8 or more and 8/2 or less.

Furthermore, for example, when the ultraviolet absorbing layer 3 contains a colorant (for example, in the case of a second ultraviolet absorbing layer 32 containing a colorant), the resin contained in the resin composition forming that layer is preferably an acrylic resin, a styrene resin, a polyester, a polyurethane, a chlorinated polyolefin, a vinyl chloride-vinyl acetate copolymer resin, a polyvinyl butyral resin, an alkyd resin, a petroleum resin, a ketone resin, an epoxy resin, a melamine resin, a fluororesin, a silicone resin, a cellulose derivative, a rubber resin, or the like.

By incorporating a coloring material into the UV-absorbing layer 3, decorative properties can be added to the resin molded product. For example, a UV-absorbing layer 3 containing a coloring material can be used to create patterns such as designs and letters. Furthermore, by incorporating a coloring material into the UV-absorbing layer 3, it can also function to conceal the coloring of the molded resin, etc.

The pattern expressed by the ultraviolet absorbing layer 3 is not particularly limited, but examples include patterns consisting of wood grain, stone grain, cloth grain, sand grain, geometric patterns, letters, etc.

The UV absorbing layer 3 preferably has a first UV absorbing layer 31 containing a UV absorber and a second UV absorbing layer 32 containing a colorant. Furthermore, the first UV absorbing layer 31 containing a UV absorber may not contain a colorant, and the second UV absorbing layer 32 containing a colorant may not contain a UV absorber. Furthermore, the first UV absorbing layer 31 containing a UV absorber is preferably located closer to the transfer substrate 1 (the side opposite the adhesive layer 2) than the second UV absorbing layer 32 containing a colorant.

From the perspective of more optimally achieving the effects of the presently disclosed invention, the content of the ultraviolet absorber contained in the first ultraviolet absorbing layer 31 is preferably 0.5% by mass or more, more preferably 1% by mass or more, and even more preferably 3% by mass or more, and is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less. Preferred ranges include approximately 0.5 to 20% by mass, approximately 0.5 to 15% by mass, approximately 0.5 to 10% by mass, approximately 1 to 20% by mass, approximately 1 to 15% by mass, approximately 1 to 10% by mass, approximately 3 to 20% by mass, approximately 3 to 15% by mass, and approximately 3 to 10% by mass.

Furthermore, from the viewpoint of more suitably exerting the effects of the present invention, the content of the colorant contained in the second ultraviolet absorbing layer 32 is preferably 1% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and is preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less. Preferred ranges include approximately 1 to 50% by mass, 1 to 40% by mass, 1 to 30% by mass, 10 to 50% by mass, 10 to 40% by mass, 10 to 30% by mass, 15 to 50% by mass, 15 to 40% by mass, and 15 to 30% by mass.

Various additives can be blended into the resin composition that forms the UV-absorbing layer 3, depending on the desired physical properties. Examples of such additives include weather resistance improvers such as light stabilizers, abrasion resistance improvers, polymerization inhibitors, crosslinking agents, infrared absorbers, antistatic agents, adhesion improvers, leveling agents, thixotropy-imparting agents, coupling agents, plasticizers, defoamers, fillers, solvents, and matting agents. These additives can be appropriately selected from commonly used additives; for example, matting agents such as silica particles and aluminum hydroxide particles can be used.

The total thickness of the ultraviolet absorbing layer 3 is preferably 0.1 μm or more, more preferably 0.5 μm or more, and even more preferably 1 μm or more. It is also preferably 10 μm or less, more preferably 8 μm or less, and even more preferably 5 μm or less. Preferred ranges include approximately 0.1 to 10 μm, approximately 0.1 to 8 μm, approximately 0.1 to 5 μm, approximately 0.5 to 10 μm, approximately 0.5 to 8 μm, approximately 0.5 to 5 μm, approximately 1 to 10 μm, approximately 1 to 8 μm, and approximately 1 to 5 μm.

The total thickness of the first ultraviolet absorbing layer 31 is preferably 0.1 μm or more, more preferably 0.5 μm or more, and even more preferably 1 μm or more. It is also preferably 5 μm or less, more preferably 4 μm or less, and even more preferably 3 μm or more. Preferred ranges include approximately 0.1 to 5 μm, approximately 0.1 to 4 μm, approximately 0.1 to 3 μm, approximately 0.5 to 5 μm, approximately 0.5 to 4 μm, approximately 0.5 to 3 μm, approximately 1 to 5 μm, approximately 1 to 4 μm, and approximately 1 to 3 μm.

The total thickness of the second ultraviolet absorbing layer 32 is preferably 0.1 μm or more, more preferably 0.5 μm or more, and even more preferably 1 μm or more. It is also preferably 5 μm or less, more preferably 4 μm or less, and even more preferably 3 μm or less. Preferred ranges include approximately 0.1 to 5 μm, approximately 0.1 to 4 μm, approximately 0.1 to 3 μm, approximately 0.5 to 5 μm, approximately 0.5 to 4 μm, approximately 0.5 to 3 μm, approximately 1 to 5 μm, approximately 1 to 4 μm, and approximately 1 to 3 μm.

The UV-absorbing layer 3 is formed using a resin composition that forms the UV-absorbing layer by a conventional coating method such as gravure coating, gravure reverse coating, gravure offset coating, spinner coating, roll coating, reverse roll coating, kiss coating, wheel coating, dip coating, solid coating by silk screen, wire bar coating, flow coating, comma coating, flow coating, brush coating, or spray coating.

(Protective layer 4)
The protective layer 4 is a layer that is provided on the transfer layer 8 as needed so as to be located on the surface of the resin molded article in order to improve the scratch resistance, chemical resistance, etc. of the resin molded article. The resin that forms the protective layer 4 is not particularly limited, and examples thereof include thermosetting resins, thermoplastic resins, and ionizing radiation curable resins. Among these, ionizing radiation curable resins are preferred from the viewpoint of achieving both excellent scratch resistance and excellent three-dimensional formability.

The thermosetting resin that forms the protective layer 4 is not particularly limited, and examples include resins containing a polyol resin and a curing agent, such as acrylic polyol; polyester polyol; urethane polyol such as polyester urethane polyol or acrylic-urethane polyol; or polyolefin polyol such as polyethylene polyol, polypropylene polyol, polybutadiene polyol, or polyisoprene polyol. The thermosetting resin may be used alone or in combination of two or more types.

The thermoplastic resin that forms the protective layer 4 is not particularly limited, and examples include acrylic resins such as polymethyl (meth)acrylate and polyethyl (meth)acrylate; polyolefins such as polypropylene and polyethylene; polycarbonate; vinyl chloride resin; polyester; acrylonitrile-butadiene-styrene resin (ABS resin); acrylonitrile-styrene-acrylic ester resin; and the like. One type of thermoplastic resin may be used alone, or two or more types may be used in combination.

(ionizing radiation curable resin)
The ionizing radiation curable resin used to form the protective layer 4 is as described above for the release layer 11. Here, ionizing radiation refers to electromagnetic waves or charged particle beams that have an energy quantum capable of polymerizing or crosslinking molecules, and typically includes ultraviolet (UV) or electron beams (EB), but also includes electromagnetic waves such as X-rays and gamma rays, and charged particle beams such as alpha rays and ion beams. Among ionizing radiation curable resins, electron beam curable resins are preferably used in forming the protective layer 4 because they can be made solvent-free, do not require a photopolymerization initiator, and provide stable curing properties.

In the laminate of the present disclosure, when an ionizing radiation curable resin is used to form the protective layer 4, the protective layer 4 in the laminate may be cured, uncured, or semi-cured. If the protective layer 4 in the laminate is uncured or semi-cured, the protective layer 4 is cured after the laminate is formed.

Examples of the monomer used as the ionizing radiation curable resin include the same monomers as those exemplified for the release layer 11.

Furthermore, examples of the oligomer used as the ionizing radiation curable resin include the same ones as those exemplified for the release layer 11.

Of the ionizing radiation curable resins listed above, from the viewpoint of achieving both excellent scratch resistance and excellent three-dimensional formability, it is preferable to use polycarbonate (meth)acrylate (such as polycarbonate-based urethane (meth)acrylate), and it is particularly preferable to use a polycarbonate (meth)acrylate (such as polycarbonate-based urethane (meth)acrylate) in combination with a polyfunctional (meth)acrylate other than the polycarbonate (meth)acrylate.

Polycarbonate (meth)acrylates can be obtained, for example, by converting some or all of the hydroxyl groups of a polycarbonate polyol to (meth)acrylates (acrylic acid esters or methacrylic acid esters). This esterification reaction can be carried out by a conventional esterification reaction. Examples include: 1) a method of condensing a polycarbonate polyol with an acrylic acid halide or a methacrylic acid halide in the presence of a base; 2) a method of condensing a polycarbonate polyol with an acrylic acid anhydride or a methacrylic acid anhydride in the presence of a catalyst; or 3) a method of condensing a polycarbonate polyol with an acrylic acid or a methacrylic acid in the presence of an acid catalyst.

The polycarbonate polyol is a polymer having a carbonate bond in the polymer backbone and two or more, preferably 2 to 50, and more preferably 3 to 50 hydroxyl groups at the terminal or side chain. A typical method for producing this polycarbonate polyol is a polycondensation reaction of a diol compound (A), a trihydric or higher polyhydric alcohol (B), and a compound (C) that serves as a carbonyl component. The diol compound (A) used as a raw material is represented by the general formula HO-R ¹ -OH. Here, R ¹ is a divalent hydrocarbon group having 2 to 20 carbon atoms and may contain an ether bond. Examples of such groups include linear or branched alkylene groups, cyclohexylene groups, and phenylene groups.

Specific examples of diol compound (A) include ethylene glycol, 1,2-propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, polyethylene glycol, neopentyl glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,3-bis(2-hydroxyethoxy)benzene, 1,4-bis(2-hydroxyethoxy)benzene, 1,4-cyclohexanediol, and 1,4-cyclohexanedimethanol. These diols may be used alone or in combination.

Examples of the trihydric or higher polyhydric alcohol (B) include alcohols such as trimethylolpropane, trimethylolethane, pentaerythritol, ditrimethylolpropane, dipentaerythritol, glycerin, and sorbitol. Furthermore, alcohols having hydroxyl groups in which 1 to 5 equivalents of ethylene oxide, propylene oxide, or other alkylene oxides have been added to the hydroxyl groups of these polyhydric alcohols may also be used. These polyhydric alcohols may be used alone or in combination of two or more.

Compound (C), which serves as the carbonyl component, is any compound selected from among carbonate diesters, phosgene, or their equivalents. Specific examples include carbonate diesters such as dimethyl carbonate, diethyl carbonate, diisopropyl carbonate, diphenyl carbonate, ethylene carbonate, and propylene carbonate; phosgene; and halogenated formates such as methyl chloroformate, ethyl chloroformate, and phenyl chloroformate. These may be used alone or in combination of two or more.

Polycarbonate polyol is synthesized by polycondensation of the diol compound (A), trihydric or higher polyhydric alcohol (B), and carbonyl component compound (C) under standard conditions. For example, the molar ratio (B:A) of the diol compound (A) to the polyhydric alcohol (B) is preferably 50:50 or greater and 99:1 or less, and the molar ratio of the carbonyl component compound (C) to the diol compound (A) and polyhydric alcohol (B) is preferably 0.2 or greater and 2 or less equivalents relative to the hydroxyl groups of the diol compound and polyhydric alcohol.

The equivalent number (eq./mol) of hydroxyl groups present in the polycarbonate polyol after the polycondensation reaction at the above-mentioned charging ratio is, on average, 3 or more per molecule, preferably 50 or less, and more preferably 20 or less. Within this range, the required amount of (meth)acrylate groups is formed by the esterification reaction described below, and the polycarbonate (meth)acrylate resin is endowed with appropriate flexibility. The terminal functional groups of this polycarbonate polyol are typically OH groups, but some of them may be carbonate groups.

The method for producing the polycarbonate polyol described above is described, for example, in JP-A-64-1726. This polycarbonate polyol can also be produced by transesterification of a polycarbonate diol with a trihydric or higher polyhydric alcohol, as described in JP-A-3-181517.

The weight-average molecular weight of the polycarbonate (meth)acrylate used in this disclosure is preferably 500 or more, more preferably 1,000 or more, and even more preferably 2,000 or more. There is no particular upper limit to the weight-average molecular weight of the polycarbonate (meth)acrylate, but from the perspective of controlling the viscosity so that it does not become too high, it is preferably 100,000 or less, more preferably 50,000 or less, and even more preferably 30,000 or less. The weight-average molecular weight of the polycarbonate (meth)acrylate preferably ranges from 500 to 100,000, more preferably 1,000 to 50,000, and particularly preferably 2,000 to 30,000. The weight-average molecular weight of the polycarbonate (meth)acrylate used in this disclosure is the average molecular weight measured by GPC analysis and converted into standard polystyrene.

In the ionizing radiation curable resin composition, polycarbonate (meth)acrylate is preferably used together with a polyfunctional (meth)acrylate other than the polycarbonate (meth)acrylate. The mass ratio of the polycarbonate (meth)acrylate to the polyfunctional (meth)acrylate (polycarbonate (meth)acrylate/polyfunctional (meth)acrylate) is more preferably 50/50 or more and 98/2 or less. When the mass ratio of the polycarbonate (meth)acrylate to the polyfunctional (meth)acrylate is less than 98/2 (i.e., when the amount of polycarbonate (meth)acrylate is 98% by mass or less of the total amount of the two components), the aforementioned durability and chemical resistance are further improved. On the other hand, when the mass ratio of polycarbonate (meth)acrylate to polyfunctional (meth)acrylate is greater than 50/50 (i.e., when the amount of polycarbonate (meth)acrylate is 50 mass% or more of the total amount of the two components), three-dimensional moldability is further improved. Preferably, the mass ratio of polycarbonate (meth)acrylate to polyfunctional (meth)acrylate is 60/40 or more and 95/5 or less.

In the present disclosure, the polyfunctional (meth)acrylate other than the polycarbonate (meth)acrylate used in combination with the polycarbonate (meth)acrylate is not particularly limited as long as it is a (meth)acrylate with two or more functionalities. Here, "bifunctional" means having two ethylenically unsaturated bonds ((meth)acryloyl groups) in the molecule. The number of functional groups is preferably two or more, or preferably six or less.

The polyfunctional (meth)acrylate used in combination with polycarbonate (meth)acrylate may be either an oligomer or a monomer, but from the perspective of achieving both excellent scratch resistance and excellent three-dimensional formability, a polyfunctional (meth)acrylate oligomer is preferred.

Examples of the polyfunctional (meth)acrylate oligomers used in combination with polycarbonate (meth)acrylate include urethane (meth)acrylate oligomers, epoxy (meth)acrylate oligomers, polyester (meth)acrylate oligomers, and polyether (meth)acrylate oligomers. Urethane (meth)acrylate oligomers can be obtained, for example, by esterifying polyurethane oligomers, obtained by reacting polyether polyols or polyester polyols with polyisocyanates, with (meth)acrylic acid. Epoxy (meth)acrylate oligomers can be obtained, for example, by reacting (meth)acrylic acid with the oxirane rings of relatively low-molecular-weight bisphenol epoxy resins or novolac epoxy resins for esterification. Carboxyl-modified epoxy (meth)acrylate oligomers, in which epoxy (meth)acrylate oligomers are partially modified with dibasic carboxylic acid anhydrides, can also be used. Polyester (meth)acrylate oligomers can be obtained, for example, by esterifying the hydroxyl groups of a polyester oligomer having hydroxyl groups at both ends, obtained by condensation of a polycarboxylic acid and a polyhydric alcohol, with (meth)acrylic acid; or by esterifying the terminal hydroxyl groups of an oligomer obtained by adding an alkylene oxide to a polycarboxylic acid with (meth)acrylic acid. Polyether (meth)acrylate oligomers can be obtained by esterifying the hydroxyl groups of a polyether polyol with (meth)acrylic acid.

Furthermore, other polyfunctional (meth)acrylate oligomers that can be used in combination with polycarbonate (meth)acrylate include highly hydrophobic polybutadiene (meth)acrylate oligomers that have (meth)acrylate groups on the side chains of polybutadiene oligomers, silicone (meth)acrylate oligomers that have polysiloxane bonds in the main chain, and aminoplast resin (meth)acrylate oligomers that are modified aminoplast resins that have many reactive groups in their small molecules.

Specific examples of the polyfunctional (meth)acrylate monomers used in combination with polycarbonate (meth)acrylate include ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, hydroxypivalic acid neopentyl glycol di(meth)acrylate, dicyclopentanyl di(meth)acrylate, caprolactone-modified dicyclopentenyl di(meth)acrylate, ethylene oxide-modified phosphate di(meth)acrylate, allylated cyclohexyl di(meth)acrylate, and isocyanurate di(meth)acrylate. ) acrylate, trimethylolpropane tri(meth)acrylate, ethylene oxide-modified trimethylolpropane tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, propionic acid-modified dipentaerythritol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propylene oxide-modified trimethylolpropane tri(meth)acrylate, tris(acryloxyethyl)isocyanurate, propionic acid-modified dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ethylene oxide-modified dipentaerythritol hexa(meth)acrylate, caprolactone-modified dipentaerythritol hexa(meth)acrylate, etc. The above-mentioned polyfunctional (meth)acrylate oligomers and polyfunctional (meth)acrylate monomers may be used alone or in combination of two or more.

In the present disclosure, monofunctional (meth)acrylates can be used in combination with the polycarbonate (meth)acrylate, as appropriate, to the extent that the objectives of the present disclosure are not impaired, for purposes such as reducing the viscosity. Examples of monofunctional (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, and isobornyl (meth)acrylate. These monofunctional (meth)acrylates can be used alone or in combination of two or more.

The content of polycarbonate (meth)acrylate in the ionizing radiation curable resin composition that forms protective layer 4 is not particularly limited, but from the viewpoint of achieving both excellent scratch resistance and excellent three-dimensional formability, it is preferably 98% by mass or less, more preferably 90% by mass or less, and also preferably 50% by mass or more, more preferably 65% by mass or more. The preferred range for the content of polycarbonate (meth)acrylate in the ionizing radiation curable resin composition that forms protective layer 4 is preferably 50% by mass or more and 98% by mass or less, more preferably 65% by mass or more and 90% by mass or less.

When the protective layer 4 is formed using an ionizing radiation curable resin, the protective layer 4 is formed, for example, by preparing an ionizing radiation curable resin composition, applying the composition, and crosslinking and curing it. The viscosity of the ionizing radiation curable resin composition may be any viscosity that allows the formation of an uncured resin layer using the application method described below.

In the present disclosure, the prepared coating liquid is applied to the desired thickness by a known method such as gravure coating, bar coating, roll coating, reverse roll coating, or comma coating, preferably gravure coating, to form an uncured resin layer.

The uncured resin layer thus formed is then irradiated with ionizing radiation such as electron beams or ultraviolet rays to cure the uncured resin layer and form protective layer 4. When using electron beams as the ionizing radiation, the acceleration voltage can be selected appropriately depending on the resin used and the layer thickness, but typically is 70 kV or more and 300 kV or less.

In addition, since the higher the acceleration voltage in electron beam irradiation, the greater the penetration ability, when a resin that is easily deteriorated by electron beam irradiation is used under the protective layer 4, the acceleration voltage is selected so that the penetration depth of the electron beam is substantially equal to the thickness of the protective layer 4. Furthermore, when the release layer 11 formed on the transfer substrate layer and the protective layer 4 are cured together with the electron beam using an electron beam, the acceleration voltage is selected so that the penetration depth of the electron beam is substantially equal to the total thickness of the release layer 11 and the protective layer 4. This makes it possible to prevent excess electron beam irradiation of the transfer substrate layer located under the release layer 11, minimizing deterioration of the transfer substrate layer due to excess electron beams.

The exposure dose is an amount that provides sufficient crosslinking density in the protective layer 4, and is preferably 30 kGy (3 Mrad) or more, and preferably 300 kGy (30 Mrad) or less, and more preferably 100 kGy (10 Mrad) or less. The exposure dose is preferably 30 kGy (3 Mrad) or more and 300 kGy (30 Mrad) or less, and more preferably 30 kGy (3 Mrad) or more and 100 kGy (10 Mrad) or less. Setting the exposure dose within this range can suppress deterioration of layers located below the protective layer 4 due to ionizing radiation that has penetrated the protective layer 4. Note that the above example is for a case in which the number of functional groups in the polyfunctional (meth)acrylate is two; an appropriate exposure dose is required depending on the number of functional groups.

Furthermore, there are no particular limitations on the electron beam source, and any of the various electron beam accelerators exemplified for the release layer 11 can be used.

When ultraviolet light is used as the ionizing radiation, light containing ultraviolet light with a wavelength of 190 nm or more and 380 nm or less should be emitted. There are no particular limitations on the ultraviolet light source, and examples include those exemplified for the release layer 11.

The thickness of protective layer 4 is not particularly limited, but is preferably 1 μm or more, more preferably 2 μm or more, even more preferably 3 μm or more, and preferably 20 μm or less, more preferably 15 μm or less. The preferred thickness range for protective layer 4 is 1 μm or more and 20 μm or less, more preferably 2 μm or more and 20 μm or less, even more preferably 3 μm or more and 15 μm or less. Meeting this thickness range allows the laminate to effectively exhibit excellent scratch resistance and excellent three-dimensional formability. Furthermore, when protective layer 4 is formed from an ionizing radiation-curable resin, it is possible to uniformly irradiate the ionizing radiation-curable resin composition with ionizing radiation, enabling uniform curing and providing economic advantages.

(Primer layer 5)
The primer layer 5 is a layer that is provided as needed between the polyolefin-containing adhesive layer 2 and the ultraviolet absorbing layer 3 for the purpose of improving adhesion between these layers. In particular, the adhesive strength between an ultraviolet absorbing layer 3 (e.g., the second ultraviolet absorbing layer 32) that uses a resin such as an acrylic resin or a vinyl chloride-vinyl acetate copolymer and the polyolefin-containing adhesive layer 2 tends to be low, but in the present disclosure, the adhesive strength between the primer layer 5 and the adhesive layer 2 is increased by providing a primer layer 5 that contains, for example, a urethane resin (polyurethane).

The primer layer 5 can be formed from a resin composition for forming a primer layer.

In the resin composition for forming the primer layer, the polyol that forms the polyurethane may be any compound having two or more hydroxyl groups in the molecule. Specific examples include polyester polyol, polyethylene glycol, polypropylene glycol, acrylic polyol, polyether polyol, etc., with acrylic polyol being preferred.

Specific examples of isocyanate compounds that form polyurethane include polyisocyanates having two or more isocyanate groups in the molecule; aromatic isocyanates such as 4,4-diphenylmethane diisocyanate; and aliphatic (or alicyclic) isocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate, and hydrogenated diphenylmethane diisocyanate.

Among polyurethanes, from the viewpoint of improving adhesion after crosslinking, a combination of an acrylic polyol or polyester polyol as the polyol and hexamethylene diisocyanate or 4,4-diphenylmethane diisocyanate as the crosslinking agent is preferred; and a combination of an acrylic polyol and hexamethylene diisocyanate is even more preferred.

The primer layer 5 may contain a resin other than polyurethane. Examples of resins other than polyurethane include acrylic resin, (meth)acrylic-urethane copolymer resin, polyester, and butyral resin. Among these resins, acrylic resin and acrylic urethane resin are preferred. When the primer layer 5 contains an acrylic resin or acrylic urethane resin, it is possible to effectively suppress foil burrs on the transfer sheet 10. These resins may be used alone or in combination of two or more.

The acrylic resin is not particularly limited, but examples include acrylic polyols, homopolymers of (meth)acrylic esters, copolymers of two or more different (meth)acrylic ester monomers, and copolymers of (meth)acrylic esters with other monomers. More specific examples of (meth)acrylic resins include (meth)acrylic esters such as polymethyl(meth)acrylate, polyethyl(meth)acrylate, polypropyl(meth)acrylate, polybutyl(meth)acrylate, methyl(meth)acrylate-butyl(meth)acrylate copolymers, ethyl(meth)acrylate-butyl(meth)acrylate copolymers, ethylene-methyl(meth)acrylate copolymers, and styrene-methyl(meth)acrylate copolymers.

When the primer layer 5 contains polyurethane and acrylic resin, from the viewpoint of achieving the effects of the presently disclosed invention while effectively suppressing foil burrs on the transfer sheet 10, the content ratio of polyurethane to acrylic resin in the primer layer 5 (polyurethane:acrylic resin) is preferably in the range of 9:1 to 5:5, and more preferably in the range of 8:2 to 6:4.

The acrylic urethane resin is not particularly limited, but examples thereof include acrylic-urethane block copolymers, and more specifically, acrylic-polyester urethane block copolymers. The ratio of acrylic to urethane in the acrylic-urethane block copolymer is not particularly limited, but examples include an acrylic/urethane ratio (mass ratio) of preferably 9/1 or less, more preferably 8/2 or less, and also preferably 1/9 or more, more preferably 2/8 or more. The preferred range for the acrylic/urethane ratio (mass ratio) is 1/9 or more and 9/1 or less, more preferably 2/8 or more and 8/2 or less.

When the primer layer 5 contains polyurethane and acrylic urethane resin, the content ratio of polyurethane to acrylic urethane resin in the primer layer 5 (polyurethane:acrylic urethane resin) is preferably in the range of 9:1 to 5:5, and more preferably in the range of 8:2 to 6:4, in order to effectively suppress foil burrs on the transfer sheet 10.

From the viewpoint of achieving the effects of the present disclosure while effectively suppressing burrs on the transfer sheet 10, the main components of the resin contained in the primer layer 5 are preferably polyurethane and acrylic resin. By "main component," we mean a resin that accounts for, for example, 50% by mass or more of the resin contained in the primer layer 5. The content of polyurethane and acrylic resin among the resins contained in the primer layer 5 is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, and even more preferably 100% by mass. In the transfer sheet 10 of the present disclosure, it is particularly preferable that the content of polyurethane and acrylic resin among the resins contained in the primer layer 5 is as described above, and that the content ratio of polyurethane to acrylic resin (polyurethane:acrylic resin) in the primer layer 5 satisfies the above range.

The primer layer 5 may contain an isocyanate compound to improve adhesion. Specific examples of isocyanate compounds include polyisocyanates having two or more isocyanate groups in the molecule; aromatic isocyanates such as 4,4-diphenylmethane diisocyanate; and aliphatic (or alicyclic) isocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate, and hydrogenated diphenylmethane diisocyanate.

The amount of isocyanate compound contained is not particularly limited, but from the standpoint of adhesion and printability when laminating adhesive layer 2 and the like, it is preferably 5 parts by mass or more, and preferably 45 parts by mass or less, and more preferably 25 parts by mass or less, relative to the resin content.

The thickness of the primer layer 5 is not particularly limited, but is, for example, 0.1 μm or more, more preferably 1 μm or more, and preferably 10 μm or less. That is, the coating amount is, for example, 0.1 g/m ² or more, preferably 1 g/m ² or more, and preferably 10 g/m ^2.
The thickness of the primer layer 5 is preferably in the range of 0.1 μm to 10 μm, more preferably 1 μm to 10 μm. When the primer layer 5 satisfies such a thickness, the adhesion to the adhesive layer 2 can be effectively improved.

Various additives can be blended into the composition that forms the primer layer 5 depending on the desired physical properties.

The primer layer 5 is formed using a resin composition for forming a primer layer by a conventional coating method such as gravure coating, gravure reverse coating, gravure offset coating, spinner coating, roll coating, reverse roll coating, kiss coating, wheel coating, dip coating, solid coating by silk screen, wire bar coating, flow coating, comma coating, flow coating, brush coating, or spray coating, or a transfer coating method.

2. Resin Molded Article and Its Manufacturing Method The resin molded article of the present disclosure is formed by integrating the transfer layer of the transfer sheet of the present disclosure with the molded resin layer. Specifically, by laminating the molded resin layer 9 on the side of the transfer sheet opposite the support, a resin molded article 21 with a transfer substrate is obtained, in which at least the molded resin layer 9, the transfer layer 8, and the transfer substrate 1 are laminated in this order (see, for example, FIG. 7). Next, by peeling the support from the resin molded article 21 with a transfer substrate, a resin molded article of the present disclosure is obtained, in which at least the molded resin layer 9 and the transfer layer 8 are laminated (see, for example, FIG. 8).

The resin molded article of the present disclosure can be produced by a production method including the following steps.
A process in which the transfer sheet 10 is placed in a mold, a fluid resin is injected into the mold from the transfer layer 8 side, the injected resin is solidified, and the transfer sheet 10 is integrated with the outer surface of the molded resin layer 9 at the same time as the injection molding.
A process for obtaining a resin molded product having a transfer layer 8 on its surface by peeling off the transfer substrate 1 from the resin molded product 21 with the transfer substrate obtained in the above process (if the release layer 11 and anti-blocking layer 6 are present, these layers are also peeled off).

When the transfer sheet is applied to, for example, an injection molding simultaneous transfer decoration method, the method for producing a resin molded product of the present disclosure includes, for example, a method including the following steps (1) to (5).
(1) First, a step of heating the transfer sheet from the transfer layer 8 side by a heating platen while the transfer layer 8 side of the transfer sheet faces the inside of a mold;
(2) A step of preforming (vacuum forming) the transfer sheet so that it conforms to the shape inside the mold, and then clamping it in close contact with the inner surface of the mold;
(3) injecting resin into the mold;
(4) a step of removing the resin molded product (resin molded product with transfer substrate) from the mold after cooling the injected resin, and (5) a step of peeling off the transfer substrate (together with the support) from the resin molded product.

In both steps (1) and (2) above, the temperature to which the transfer sheet is heated is preferably in the range of near the glass transition temperature or higher of the transfer substrate 1, but below the melting temperature (or melting point). It is usually more preferable to heat the transfer sheet at a temperature near the glass transition temperature. Note that "near the glass transition temperature" refers to a range of approximately ±5°C from the glass transition temperature, and when a polyester film, which is suitable for the transfer substrate 1, is used, this is generally around 70 to 130°C. Note that when a mold with a simple shape is used, the steps of heating the transfer sheet and preforming the transfer sheet can be omitted, and the transfer sheet can be molded into the shape of the mold using the heat and pressure of the injected resin in step (3) described below.

In step (3) above, the molding resin, described below, is melted and injected into the cavity to integrate the transfer sheet and molding resin. If the molding resin is a thermoplastic resin, it is heated and melted to a fluid state. If the molding resin is a thermosetting resin, the uncured liquid composition is injected at room temperature or in a fluid state after being appropriately heated, and then cooled and solidified. This causes the transfer sheet to be integrated and attached to the formed resin molding, resulting in a resin molded product with a transfer substrate. The heating temperature for the molding resin depends on the type of molding resin, but is generally 180°C or higher and 320°C or lower.

The resin molded article with the transfer substrate thus obtained is cooled in step (4) and removed from the mold, and then in step (5) the support is peeled off from the protective layer 4 to obtain a resin molded article. The step of peeling off the support from the protective layer 4 may be carried out simultaneously with the step of removing the decorated resin molded article from the mold. In other words, step (5) may be included in step (4).

In the resin molded product of the present disclosure, the molded resin layer 9 may be formed from a resin selected according to the intended use. The molding resin that forms the molded resin layer 9 may be a thermoplastic resin or a thermosetting resin.

Examples of thermoplastic resins include polyolefins such as polyethylene and polypropylene, ABS resins, styrene resins, polycarbonates, acrylic resins, and vinyl chloride resins. These thermoplastic resins may be used alone or in combination of two or more. The molded resin product 20 of the present disclosure preferably contains a polyolefin, and more preferably polypropylene, as the molding resin forming the molded resin layer 9. Furthermore, the molded resin layer 9 may be formed from polypropylene. The resin contained in the molded resin layer 9 may be substantially polypropylene alone. "The resin contained in the molded resin layer 9 being substantially polypropylene alone" means that the proportion of polypropylene in the resin contained in the molded resin layer 9 is, for example, 90% by mass or more, preferably 95% by mass or more, more preferably 98% by mass or more, and even more preferably 99% by mass or more.

Examples of thermosetting resins include polyurethane and epoxy resin. These thermosetting resins may be used alone or in combination of two or more.

The resin molded article of the present disclosure preferably has a toluene concentration of 1.0 mg/m or ^less when measured in accordance with the provisions of ISO 12219-2: 2012 at 80°C for 2 hours. The toluene concentration is measured by the following method.

<VOC evaluation of resin molded products (toluene)>
In accordance with the provisions of ISO12219-2:2012 (Interior air of road vehicles - Part 2: Screening method for determining emissions of volatile organic compounds from interior parts and materials - Bag method), a resin molded product (size: 50 x 150 x 4 mm) was placed in a sealed container (a 10 L Tedlar bag) and stored in a thermostatic chamber at 80°C for 2 hours, and the toluene concentration (mg/m ³ ) in the air inside the Tedlar bag was measured.

In addition, in resin molded products with a transfer substrate, the transfer substrate serves as a protective sheet for the resin molded product, so after production, the resin molded product with a transfer substrate can be stored as is without being peeled off, and the support can be peeled off when it is time to use it. Using it in this manner can prevent scratches on the resin molded product due to friction during transportation, etc.

The resin molded products disclosed herein can be used, for example, as interior or exterior materials for vehicles such as automobiles; building materials such as window frames and door frames; interior materials for buildings such as walls, floors, and ceilings; housings for home appliances such as television sets and air conditioners; containers, etc.

The present disclosure will be explained in detail below using examples and comparative examples. However, the present disclosure is not limited to the examples.

<Production of transfer sheet>
A polyethylene terephthalate film (75 μm thick) with an easy-adhesive layer formed on one side was used as the transfer substrate. An anti-blocking layer (1.5 μm thick, acrylic resin containing 1% silica particles) was applied to the side of the polyethylene terephthalate film opposite the easy-adhesive layer. A coating liquid primarily composed of an ionizing radiation-curable resin composition was gravure printed on the easy-adhesive layer surface of the polyethylene terephthalate film to form a release layer (1 μm thick). Next, electron beams were irradiated from above this coating film at an acceleration voltage of 165 kV and an exposure dose of 50 kGy (5 Mrad) to cure the release layer-forming coating film and form a protective layer. Next, the ionizing radiation-curable resin composition was applied to the release layer using a bar coder to a thickness of 2 μm after curing (i.e., a protective layer thickness of 2 μm), forming a protective layer-forming coating film. The ionizing radiation-curable resin composition was urethane acrylate.

Next, the coating film was irradiated with an electron beam at an acceleration voltage of 165 kV and an exposure dose of 50 kGy (5 Mrad) to cure the protective layer-forming coating film and form a protective layer. A first ultraviolet absorbing layer (2 μm thick) was then formed on this protective layer by gravure printing using a resin composition for forming a first ultraviolet absorbing layer. Resin composition A for forming the first ultraviolet absorbing layer used in Examples 1 to 4 and Comparative Example 2 was a resin composition comprising 3 parts by mass of an ultraviolet absorber (triazine-based ultraviolet absorber) and 100 parts by mass of a binder resin (a mixture of an acrylic polyol resin and a vinyl chloride-vinyl acetate copolymer resin). Resin composition B for forming the first ultraviolet absorbing layer used in Example 5 and Comparative Example 1 was a resin composition obtained by removing the ultraviolet absorber from resin composition A.

Next, for Examples 1 to 3, 5, and Comparative Example 2, a second UV-absorbing layer (corresponding to a design layer (thickness: 5 μm)) bearing the design shown in Table 1 was formed on the first UV-absorbing layer by gravure printing using an ink composition containing 20 parts by weight of pigment and 80 parts by weight of binder resin (50% by weight of acrylic resin, 50% by weight of vinyl chloride-vinyl acetate copolymer resin). Next, a primer layer (thickness: 1.5 μm) was formed on the second UV-absorbing layer by gravure printing using a resin composition for forming a primer layer. The resin composition for forming the primer layer contained urethane resin and acrylic resin (acrylic polyol), with a ratio of urethane resin to acrylic resin (urethane resin:acrylic resin) of 40:60. Additionally, 10 parts by weight of hexamethylene diisocyanate was added to the resin composition per 100 parts by weight of resin.

On the other hand, for Example 4 and Comparative Example 1, a second UV-absorbing layer was not laminated on the first UV-absorbing layer, and instead a primer layer (2 μm thick) was formed on the first UV-absorbing layer by gravure printing using the same resin composition for forming the primer layer as in Examples 1 to 3, 5, and Comparative Example 2.

An adhesive layer (1.5 μm thick) was formed on the primer layer by gravure printing using a resin composition for forming the adhesive layer. The resin contained in the resin composition for forming the adhesive layer was polyolefin in Examples 1 to 5 and Comparative Example 1, and acrylic resin (PMMA) in Comparative Example 2. Hydrogenated thermoplastic elastomer (SEBS ) was used as the polyolefin in Examples 1 to 2, 4 to 5, and Comparative Example 1, and chlorinated polypropylene was used in Example 3. Toluene was used as the solvent for the resin composition for forming the adhesive layer.

As a result of the above, a laminate was obtained in which an anti-blocking layer, transfer substrate, release layer, protective layer, first UV absorbing layer, second UV absorbing layer, primer layer, and adhesive layer were laminated in this order.

<Light transmittance at a wavelength of 330 nm>
The light transmittance of each of the obtained transfer sheets at a wavelength of 330 nm was measured using the following method. The results are shown in Table 1. The light transmittance was measured using an ultraviolet-visible spectrophotometer (UH4150, manufactured by Hitachi High-Tech Corporation) in the wavelength range of 300 nm to 800 nm, and the value at a wavelength of 330 nm in the obtained spectral transmittance spectrum was taken as the light transmittance. After measuring the spectral transmittance of the transfer sheet, the transfer layer was removed from the transfer sheet, and the spectral transmittance of the support alone was measured. The spectral transmittance of the transfer layer was determined by subtracting the spectral transmittance of the support alone from the spectral transmittance of the transfer sheet. A D65 light source was used.

[Manufacturing of resin molded products]
Each of the resulting transfer sheets was placed in a mold, heated to 350°C with an infrared heater for 7 seconds, and preformed to fit the shape (plate-like) inside the mold using vacuum molding, followed by clamping (maximum stretch ratio of 50%). Then, injection resin was injected into the mold cavity, and the transfer sheet and the injection resin were integrated to obtain a resin molded article with a transfer substrate, in which the transfer sheet was integrated with the molded resin layer. For transfer at a molding resin temperature of 200°C, polypropylene resin was used as the injection resin. The resin molded article with the transfer substrate was removed from the mold, and the support (transfer substrate, antiblocking layer, and release layer) was simultaneously peeled and removed from the transfer layer to obtain a resin molded article.

<Weather resistance evaluation>
The color difference ΔE before and after the weather resistance test for the resin molded article obtained above was measured in accordance with JIS Z8722 (2009). The weather resistance test was carried out using a xenon weatherometer Ci-4000 manufactured by Atlas Co., Ltd. under the following conditions until the integrated illuminance at 340 nm reached 1000 kJ/ ^m2 .
Furthermore, an adhesion test (adhesion test) was also conducted by a cross-cut method in accordance with JIS K5600-5-6 (1999), and the weather resistance was evaluated from the results of both tests. The results are shown in Table 1.

(Weather resistance test conditions)
Step 1: 3.8 hours Irradiance: 60 W/ ^m2
Black panel temperature: 89°C
Humidity: 50%RH
Step 2: 1 hour Irradiance: 60 W/ ^m2
Black panel temperature: 38°C
Humidity: 95%RH

(Weather resistance evaluation criteria)
A+: The color difference ΔE before and after the weather resistance test was less than 2, and no peeling occurred in the adhesion test.
A: The color difference ΔE before and after the weather resistance test was 2 or more and less than 3, and no peeling was observed in the adhesion test.
B: The color difference ΔE before and after the weather resistance test was 3 or more, and no peeling occurred in the adhesion test.
C: The color difference ΔE before and after the weather resistance test was 3 or more, and peeling occurred in the adhesion test.

<Evaluation of Adhesion of Transfer Sheet>
The resin molded article obtained above was subjected to an adhesion test (adhesion test) by the cross-cut method in accordance with JIS K5600-5-6 (1999) to evaluate the adhesion of the transfer sheet to the molded resin layer. The results are shown in Table 1.

(Adhesion evaluation criteria)
A: No peeling occurred in the adhesion test to the resin molded product.

B: Peeling occurred in the adhesion test to the resin molded product.
C: When the resin molded product was produced, the adhesive layer and the molded resin layer did not adhere to each other.

DESCRIPTION OF SYMBOLS 1 Transfer substrate 2 Adhesive layer 3 Ultraviolet absorbing layer 31 First ultraviolet absorbing layer 32 Second ultraviolet absorbing layer 4 Protective layer 5 Primer layer 6 Anti-blocking layer 8 Transfer layer 9 Molded resin layer 10 Transfer sheet 11 Release layer 20 Resin molded product 21 Resin molded product with transfer substrate

Claims (11)

A transfer sheet in which at least a transfer substrate and a transfer layer are laminated,
the transfer layer includes an ultraviolet absorbing layer and an adhesive layer in this order from the transfer substrate side,
the surface of the transfer layer opposite to the transfer substrate side is constituted by the adhesive layer,
the adhesive layer comprises a polyolefin;
The content of the polyolefin in the resin contained in the adhesive layer is 50% by mass or more,
the polyolefin is a thermoplastic elastomer resin,
The transfer layer has a light transmittance of 20% or less at a wavelength of 330 nm. The transfer sheet according to claim 1, wherein the transfer layer is used in an application in which it is laminated with a molding resin containing polyolefin. The transfer sheet according to claim 1 or 2, wherein the ultraviolet absorbing layer contains at least one of an ultraviolet absorber and a colorant. The transfer sheet according to claim 1 or 2, wherein the ultraviolet absorbing layer comprises a first ultraviolet absorbing layer containing an ultraviolet absorber and a second ultraviolet absorbing layer containing a colorant. The transfer sheet according to claim 4 , wherein the first ultraviolet absorbing layer is located closer to the transfer substrate than the second ultraviolet absorbing layer. The transfer sheet according to claim 1 or 2, wherein the transfer layer further comprises a protective layer on the transfer substrate side of the transfer layer. The transfer sheet according to claim 1 or 2, further comprising a release layer between the transfer layer and the transfer substrate. A decorated resin molded product with a transfer substrate, in which at least a molded resin layer, a transfer layer, and a transfer substrate are laminated in this order,
the transfer layer includes an ultraviolet absorbing layer and an adhesive layer in this order from the transfer substrate side,
the surface of the transfer layer opposite to the transfer substrate side is constituted by the adhesive layer,
the adhesive layer comprises a polyolefin;
The content of the polyolefin in the resin contained in the adhesive layer is 50% by mass or more,
the polyolefin is a thermoplastic elastomer resin,
The transfer layer has a light transmittance of 20% or less at a wavelength of 330 nm. The resin molded product with transfer substrate described in claim 8, wherein the molded resin layer contains polyolefin. A resin molded product having at least a molded resin layer and a transfer layer laminated in this order,
the transfer layer includes an ultraviolet absorbing layer and an adhesive layer in this order from the side opposite to the molded resin layer,
a surface of the transfer layer on the side of the molded resin layer is formed by the adhesive layer;
the adhesive layer comprises a polyolefin;
The content of the polyolefin in the resin contained in the adhesive layer is 50% by mass or more,
the polyolefin is a thermoplastic elastomer resin,
The transfer layer has a light transmittance of 20% or less at a wavelength of 330 nm. The resin molded product according to claim 10 , wherein the molded resin layer contains a polyolefin.