Patent Description:
Conventionally, in the fields such as household electric appliances, automobile interior parts, and miscellaneous goods, high functionality and design decorativeness have been exhibited by decorating the surface of the product with, for example, characters and patterns. A transfer method is known as a method of decorating the surface of a product. The transfer method is a method of decoration by using a transfer sheet having a transfer layer including, for example, a release layer, a pattern layer, and an adhesive layer formed on a substrate, heating and pressurizing to bring the transfer sheet into close contact with the object to be transferred, peeling off the substrate, and transferring only the transfer layer to the surface of the object to be transferred.

For products that are required to have matt feeling as a design, a transfer sheet provided with a matting layer having fine unevenness is used for decoration. PTL1, PTL2 and PTL3 disclose methods for producing a molded article with different matt feeling on a portion of its surface by using a transfer sheet with a matting layer provided on a portion of the substrate.

In the methods described in PTL1 and PTL2, a thermosetting resin is used for the matting layer. When the degree of curing of the matting layer is insufficient, the adhesiveness between the matting layer and the release layer is reduced, and a problem has been that the release layer remains on a portion of the protective layer after being peeled off (defective transfer).

The present invention has been made in consideration of such situations, and an object of thereof is to provide a transfer sheet with good transferability that is capable of imparting a design having a gloss difference to a decorative molded article. Another object of the present invention is to provide a method for producing a decorative molded article, the method enabling, by using the transfer sheet of the present invention, impartment of a design having a gloss difference to the decorative molded article and suppression of occurrence of a defective transfer.

The object is achieved by the subject-matter of claims <NUM> and <NUM>. Advantageous further developments are subject-matter of the dependent claims.

The transfer sheet of the present invention can provide good adhesiveness between the release layer and the uneven layer, and can impart a design having a gloss difference to a decorative molded article. By using the transfer sheet of the present invention, when the release sheet is peeled off during the producing process of a decorative molded article, peeling between the release layer and the uneven layer can be suppressed. As a result, the occurrence of a defective transfer can be suppressed.

The present invention provides a transfer sheet comprising a transfer layer on a release sheet, wherein the release sheet comprises: a substrate; an uneven layer provided on a portion of one surface of the substrate and containing a matting agent and a binder resin comprising a thermoplastic resin; and a release layer provided on the uneven layer and on a portion of the substrate where the uneven layer is not formed.

<FIG> is a schematic cross-sectional view showing one embodiment of a transfer sheet of the present invention. A transfer sheet <NUM> in <FIG> includes a release sheet <NUM> and a transfer layer <NUM>.

In <FIG>, the release sheet <NUM> comprises: an uneven layer <NUM> provided on one surface of a substrate <NUM>; and a release layer <NUM> formed on the substrate <NUM> and the uneven layer <NUM>.

In <FIG>, a transfer layer <NUM> includes a protective layer <NUM>, a print layer <NUM>, and an adhesive layer <NUM> in this order from the side of the release sheet <NUM>. The protective layer <NUM> and the release layer <NUM> are in contact with each other. The transfer layer <NUM> may further have a primer layer <NUM> between the protective layer <NUM> and the print layer <NUM>.

As illustrated in <FIG>, the uneven layer <NUM> is formed on a portion of one surface of the substrate <NUM> in a predetermined pattern. That is, the transfer sheet <NUM> has, in the surface of the substrate <NUM>, a region where the uneven layer <NUM> is formed (reference sign A in <FIG>) and a region where the uneven layer is not formed (reference sign B in <FIG>). It is preferable that a plurality of regions A should be provided in the surface of the substrate <NUM>. Corresponding to the pattern of the uneven layer <NUM>, patterns are formed on the release layer <NUM> and the protective layer <NUM>.

Hereinafter, each layer of the transfer sheet will be described in detail. Note that the notation of the numerical range "AA to BB" as used herein means "AA or more and BB or less".

The form of a substrate may be either sheet shape or film shape.

Examples of the substrates include a plastic film composed of resins such as: polyolefin-based resins including polyethylene and polypropylene; vinyl-based resins including polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene/vinyl acetate copolymer, and ethylene/vinyl alcohol copolymer; polyester-based resins including polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate; acrylic-based resins such as polymethyl (meth)acrylate and polyethyl (meth)acrylate; styrene-based resins including polystyrene; and polyamide-based resins represented by nylon <NUM> or nylon <NUM>.

Of these plastic films, a biaxially stretched polyester film having excellent heat resistance and dimensional stability is preferable.

The thickness of a substrate is preferably <NUM> to <NUM>, and more preferably <NUM> to <NUM>.

Also, for the purpose of enhancing the adhesiveness of the substrate with the uneven layer and the release layer, the surface of the substrate may be subjected to a physical treatment such as corona discharge treatment or oxidation treatment, or may be coated with an anchor agent or a coating material called a primer, in advance.

The uneven layer is provided at least on a portion of one surface of the substrate. By forming the uneven layer on a portion of the surface of the substrate, an uneven profile caused by the uneven layer can be imparted to the surface of the protective layer (the interface between the protective layer and the release layer). By using the transfer sheet of the present invention, it becomes possible to produce a decorative molded article to which a design of a pattern having a gloss difference is imparted in the surface of the protective layer.

In the present invention, the uneven layer is required to contain a binder resin and a matting agent, and the binder resin is required to comprise a thermoplastic resin.

In the case where the uneven layer is formed with a thermosetting resin, since the release layer is formed after curing the uneven layer, the adhesiveness between the uneven layer and the release layer becomes poor. Therefore, when transferring to the adherend, the uneven layer and the release layer may be peeled off from each other and the release layer may remain on the decorative molded article. In addition, the profile of the uneven layer may be disrupted due to curing shrinkage, and the design decorativeness of the matt part may be deteriorated when made into a decorative molded article.

Moreover, in the case where the release layer is formed on the uneven layer without completely curing the thermosetting resin at the time of formation of the uneven layer, there is a possibility that the uneven layer will be swollen by the solvent contained in the release layer-forming coating liquid depending on the degree of curing. Due to this, there is a risk that the design decorativeness of the matt part may be deteriorated when made into a decorative molded article.

In the present invention, by forming the uneven layer using a thermoplastic resin as the main component of the binder resin, it becomes possible to provide good adhesiveness between the release layer and the uneven layer. As a result, when the transfer sheet of the present invention is used for transfer, the difference in peel strength between the release layer and the transfer layer (protective layer) can be made less likely to occur, and good peelability can be provided. In addition, when using a thermoplastic resin, there is no influence of curing shrinkage or swelling caused by solvents, and therefore, the uneven profile becomes smooth, which also provides a good appearance when made into a decorative molded article. In the present invention, the binder resin should consist substantially of a thermoplastic resin. In the present invention, the term "substantially" means that the proportion of the thermoplastic resin in the binder resin is <NUM>% or more, preferably <NUM>% or more, and more preferably <NUM>%.

The thickness of the uneven layer after drying is preferably <NUM> or more and <NUM> or less, more preferably <NUM> or more and <NUM> or less, and still more preferably <NUM> or more and <NUM> or less. Note that the thickness of the uneven layer is the average value obtained by measuring the thickness of the uneven layer at arbitrary <NUM> points using a scanning electron microscope (SEM).

The area proportion of the uneven layer in the surface of the substrate is preferably <NUM>% or more, more preferably <NUM>% or more, and still more preferably <NUM>% or more. In addition, the area proportion is preferably <NUM>% or less, more preferably <NUM>% or less, and still more preferably <NUM>% or less.

As for the thermoplastic resin, a polyolefin resin such as polypropylene and polyethylene, a polyester resin, a polycarbonate resin, an acrylonitrile-butadienestyrene resin (hereinafter, also referred to as an "ABS resin"), an acrylic resin, a vinyl chloride resin, a cellulose resin, and the like can be used, for example. In the present invention, the resins listed above can be used alone or in combination of plural kinds.

Among the above, it is preferable that the thermoplastic resin should be an acrylic resin or a cellulose resin from the viewpoints of dispersibility of the matting agent and of adhesiveness with the release layer. In addition, even when ionizing radiation is used upon the formation of the protective layer or the like, which will be mentioned later, the acrylic resin and the cellulose resin have stability against ionizing radiation and can thus be suitably used. The acrylic resin is not specifically limited, but examples thereof 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 specifically, examples of the (meth)acrylic resin include a (meth)acrylic acid ester such as polymethyl (meth)acrylate, polyethyl (meth)acrylate, polypropyl (meth)acrylate, polybutyl (meth)acrylate, a methyl (meth)acrylate-butyl (meth)acrylate copolymer, an ethyl (meth)acrylate-butyl (meth)acrylate copolymer, an ethylene-methyl (meth)acrylate copolymer, and a styrene-methyl (meth)acrylate copolymer. Examples of the cellulose resin include a nitrocellulose resin.

The thermoplastic resin described above preferably has a weight average molecular weight of <NUM>,<NUM> or more and <NUM>,<NUM> or less, and more preferably <NUM>,<NUM> or more and <NUM>,<NUM> or less. When the molecular weight is in the above range, it is easy to prepare the uneven layer-forming coating liquid and the profile stability of the uneven layer can be made good. Note that the "weight average molecular weight" here means the weight average molecular weight in terms of polystyrene as measured by gel permeation chromatography (GPC).

The matting agent contained in the uneven layer preferably has an average particle size of <NUM> or more. When the average particle size of the matting agent is <NUM> or more, the uneven profile caused by the uneven layer is easily formed on the protective layer. In order to impart an uneven profile with a sufficient size to the protective layer, the average particle size of the matting agent is preferably <NUM> or more, more preferably <NUM> or more, and still more preferably <NUM> or more. In addition, in consideration of the visibility of the print layer in the region where the uneven profile caused by the uneven layer is imparted and of the ease with which the uneven layer can be formed when made into a decorative molded article, the average particle size of the matting agent is preferably <NUM> or less, more preferably <NUM> or less, and still more preferably <NUM> or less.

The ratio of the average particle size of the matting agent to the thickness of the uneven layer is preferably <NUM> or more, more preferably <NUM> or more, and still more preferably <NUM> or more. When the ratio satisfies the above values, a sufficient matt effect of the decorative molded article can be imparted. On the other hand, when the uneven layer is thin in relation to the average particle size of the matting agent, the matting agent may fall out of the uneven layer. Therefore, in consideration of the retention properties of the matting agent, the ratio is preferably <NUM> or less, more preferably <NUM> or less, and still more preferably <NUM> or less.

As used herein, the average particle size is the average value of particle sizes (arithmetic mean size) measured for <NUM> randomly selected, non-aggregated particles by observing a cross-section of the layer in the thickness direction with a scanning electron microscope (SEM) under conditions with an acceleration voltage of <NUM> kV and a magnification of <NUM>,<NUM> times.

The matting agent can be an inorganic particle or an organic particle.

Examples of the inorganic particle include silica, alumina, clay, talc, diatomaceous earth, zeolite, calcium carbonate, barium sulfate, zinc oxide, titanium dioxide, and glass beads. Also, examples of the organic particle include a variety of synthetic resin particles, such as a melamine resin, a benzoguanamine resin, a benzoguanamine/melamine/formalin condensation product, an acrylic resin, a urethane resin, and a styrene resin. One of them may be used, or two may be mixed for use. The particle may be spherical or irregular in shape.

In particular, a silica particle is preferable because it provides a good matting effect on the surface of the decorative molded article and has an advantage of low production cost.

In the present invention, the matting agent is contained in an amount of <NUM> parts by mass or more and <NUM> parts by mass or less (solid content) based on <NUM> parts by mass (solid content) of the binder resin. When the amount thereof is <NUM> parts by mass or more, it is possible to form a moderate and fine uneven profile on the surface of the uneven layer and on the surface of the release layer over the uneven layer. As a result, it is possible to impart the desired matt design to the decorative molded article. When an uneven layer containing a thermosetting resin and a matting agent is formed, the flexibility of the layer is low, which may cause the uneven layer to be cracked during the producing process of a decorative molded article, disrupting its shape and resulting in poor design decorativeness of the matt part when made into a decorative molded article. Under such circumstances, it was not possible to add a matting agent in a large amount when using a thermosetting resin. In the present invention, it is thought that, by forming the uneven layer with a thermoplastic resin, the uneven layer has flexibility even when the matting agent is incorporated in the above amount, and the profile of the uneven layer is retained during the producing process of a decorative molded article.

Considering the formability of the uneven profile, the content of the matting agent is more preferably <NUM> parts by mass or more, and still more preferably <NUM> parts by mass or more. By setting the content thereof to <NUM> parts by mass or less, a reduction in the film strength of the uneven layer can be suppressed, and the uneven profile can be maintained during the producing process of the transfer sheet and the producing process of the decorative molded article. In addition, when the release sheet is peeled off, the peel strength can be made approximately uniform to suppress a defective transfer. Furthermore, good visibility of the print layer is provided when made into a decorative molded article. The content of the matting agent is more preferably <NUM> parts by mass or less, and still more preferably <NUM> parts by mass or less.

It is preferable that the formation pattern of the uneven layer should be selected as appropriate depending on the pattern of the print layer, which will be mentioned later. Examples of the pattern include wood, stone, fabric, sand, circle, square, polygon, geometric patterns, and characters.

In the formation of the uneven layer, at first, an uneven layer-forming coating liquid is prepared by adding an additive agent as necessary to a thermoplastic resin, which is the binder resin, and a matting agent, followed by the addition of an appropriate solvent. This coating liquid is applied onto the substrate by a known means such as gravure printing method and screen printing method, and then dried to form the uneven layer.

The release layer is provided on the uneven layer and on the substrate. In the region where the uneven layer is provided, as illustrated in <FIG>, the release sheet is configured in the order of the substrate, uneven layer, and release layer in the thickness direction. In contrast, in the region where the uneven layer is not provided, it is configured in the order of the substrate and the release layer in the thickness direction.

The surface of the release layer on the opposite side of the substrate has different surface profiles in a region formed on the uneven layer (reference sign A in <FIG>) and in a region not on the uneven layer (reference sign B in <FIG>). That is, a pattern corresponding to the pattern of the uneven layer is formed on the surface of the release layer on the opposite side of the substrate.

The resin component of the release layer is not particularly limited as long as it is a material that has a low adhesion strength to the protective layer and is capable of easily peeling off the transfer layer from the substrate. Examples thereof include a cured product of a thermosetting resin composition or a cured product of an ionizing radiation curable resin composition. Specific examples thereof include a fluororesin, a silicone resin, an acrylic resin, a polyester resin, a polycarbonate resin, a polyolefin resin, a polystyrene resin, a polyurethane resin, and a vinyl chloride-vinyl acetate copolymer resin. Among these resin components, a cured product of an ionizing radiation curable resin composition is preferable because it is excellent in strength and can also be cured instantaneously and thus impart a correct and accurate profile. A cured product of an electron beam curable resin composition is more preferable.

The ionizing radiation curable resin is a resin that is crosslinked and cured by irradiation with ionizing radiation, and has an ionizing radiation curable functional group. The ionizing radiation curable functional group is a group that is crosslinked and cured by irradiation with ionizing radiation, and preferable examples thereof include a functional group having an ethylenic double bond such as a (meth)acryloyl group, a vinyl group, and an allyl group. In addition, ionizing radiation means an electromagnetic wave or a charged particle beam having an energy quantum capable of polymerizing or crosslinking molecules; ultraviolet rays (UV) or electron beams (EB) are typically used; and electromagnetic waves such as X-rays and γ-rays and charged particle beams such as α-rays and ion rays are also included. Of these, the cured product of the electron beam curable resin composition is particularly preferable.

Specifically, the ionizing radiation curable resin can be used by appropriately selecting from the group consisting of polymerizable monomers and polymerizable oligomers commonly used as ionizing radiation curable resins.

As a polymerizable monomer, a (meth)acrylate-based monomer having a radically polymerizable unsaturated group in the molecule is preferable, and a polyfunctional (meth)acrylate monomer is particularly preferable.

Examples of the polyfunctional (meth)acrylate monomer include a (meth)acrylate monomer having two or more ionizing radiation curable functional groups in the molecule and having at least a (meth)acryloyl group as the functional group.

From the viewpoints of heat resistance and moldability, the number of functional groups is preferably <NUM> or more and <NUM> or less, more preferably <NUM> or more and <NUM> or less, still more preferably <NUM> or more and <NUM> or less, and particularly preferably <NUM> or more and <NUM> or less. These polyfunctional (meta)acrylate monomers may be used singly or in combination of two or more. In addition, one or more of these polyfunctional (meth)acrylate monomers and one or more of the polymerizable oligomers described below may be mixed into a composition for use. Preparing a composition by mixing both the monomer and the oligomer can adjust, for example, the crosslink density of a cured product and the molecular weight between crosslinks, and can adjust various physical properties of the cured product.

Examples of the polymerizable oligomer include a (meth)acrylate oligomer having two or more ionizing radiation curable functional groups in the molecule and having at least a (meth)acryloyl group as the functional group. Examples thereof include urethane (meth)acrylate oligomer, epoxy (meth)acrylate oligomer, polyester (meth)acrylate oligomer, polyether (meth)acrylate oligomer, polycarbonate (meth)acrylate oligomer, and acrylic (meth)acrylate oligomer.

From the viewpoints of heat resistance and moldability, the number of functional groups of these polymerizable oligomers is preferably <NUM> or more and <NUM> or less, more preferably <NUM> or less as the upper limit, still more preferably <NUM> or less, and particularly preferably <NUM> or less.

In particular, it is preferable that the resin component should be an acryl (meth)acrylate compound or a urethane (meth)acrylate compound, considering the adhesiveness with the uneven layer. Here, "(meth)acrylate" means "acrylate or methacrylate". The resin component may be any of the acryl (meth)acrylate compound and the urethane (meth)acrylate compound, or it may be a mixture thereof. The acryl (meth)acrylate compound and the urethane (meth)acrylate compound may each be a monomer, an oligomer, or a mixture of monomer and oligomer.

From the viewpoints of heat resistance and moldability, the weight average molecular weight of the monomer and oligomer used for a release layer is preferably <NUM> or more and <NUM> or less, more preferably <NUM> or more and <NUM> or less, and still more preferably <NUM> or more and <NUM> or less. The weight average molecular weight is an average molecular weight measured by GPC analysis and converted with standard polystyrene.

Additives such as curing agents and polymerization initiators may be added to a resin composition as necessary.

The release layer may contain a release agent to improve releasability from the protective layer.

Examples of the release agent include waxes such as a synthetic wax and a natural wax. Examples of the synthetic wax include a polyolefin wax such as a polyethylene wax and a polypropylene wax. In addition, from the viewpoints of improvement in the hardness of the release layer, suppression of bleeding of the release agent, and dispersibility of the particles, it is preferable to use a crosslinking curable release component such as a reactive silicone as the release agent.

The mass ratio of the releasing agent to the total solid content of the release layer is preferably <NUM> to <NUM>% by mass, and more preferably <NUM> to <NUM>% by mass.

It is preferable for the release layer to have a thickness that allows the uneven profile formed on the surface of the release layer to follow the profile of the uneven layer well, that allows the release layer to be easily formed, and that provides good peelability from the protective layer. Specifically, the thickness of the release layer is preferably <NUM> or more and <NUM> or less, and is more preferably <NUM> or more and <NUM> or less.

The release layer may further contain a matting agent. In this manner, when made into a decorative molded article, it is possible to provide matt feeling as a whole, while further distinguishing the gloss difference in every region. As the matting agent, the same one used for the uneven layer can be used. In particular, from the viewpoint of cost, it is preferable to contain a silica particle.

When the release layer contains a matting agent, it is preferable that the amount of the matting agent added should be less than the amount added in the uneven layer. Specifically, as for the amount added, the matting agent is preferably contained in an amount of <NUM> parts by mass or more and <NUM> parts by mass or less (solid content), and more preferably in an amount of <NUM> parts by mass or more and <NUM> parts by mass or less, based on <NUM> parts by mass (solid content) of the resin component of the release layer. When the amount added is in the above range, it is possible to provide the desired matt design to the decorative molded article.

The average particle size of the matting agent contained in the release layer is preferably <NUM> or more, and is more preferably <NUM> or more. When the average particle size of the matting agent is <NUM> or more, the uneven profile due to the release layer is easily formed on the protective layer. In consideration of the visibility of the print layer and the like when made into a decorative molded article, the average particle size of the matting agent contained in the release layer is preferably <NUM> or less, and is more preferably <NUM> or less.

The ratio of the average particle size of the matting agent to the thickness of the release layer is preferably <NUM> or more, more preferably <NUM> or more, and still more preferably <NUM> or more. When the ratio satisfies the above values, a sufficient matt effect of the decorative molded article can be imparted. On the other hand, when the release layer is thin in relation to the average particle size of the matting agent, the matting agent may fall out of the uneven layer. Therefore, in consideration of the retention properties of the matting agent, the ratio is preferably <NUM> or less, more preferably <NUM> or less, and still more preferably <NUM> or less.

In order to create a design in which there is a gloss difference between the area corresponding to the uneven layer and the surrounding area (the area where the uneven layer is not provided) when made into a decorative molded article, it is preferable to make the average particle size, the amount added, and the ratio of the matting agent average particle size to the layer thickness of the matting agents contained in the uneven layer and the release layer different from each other. An aspect in which the uneven layer exhibits a more matted design compared to the release layer is more preferable.

The release layer can be formed by a known printing method such as a gravure printing method, an offset printing method, a letterpress printing method, and a silk screen printing method.

The resin layer (blocking resin layer) containing a filler may be formed between a substrate and a pattern layer. Forming the resin layer can prevent blocking when a roll-shaped transfer film is produced.

An antistatic layer may be provided on a substrate surface that is opposite side of a release layer. The antistatic layer is preferably provided between the substrate and a pattern layer. Providing the antistatic layer can suppress the charge on a transfer sheet, thereby reducing foreign matter adhesion for example. This can improve transfer workability.

The antistatic layer may be in contact with the substrate, and the above blocking preventive layer or primer layer may be provided between the antistatic layer and the substrate.

The protective layer is provided on the release sheet side of the transfer layer. The protective layer has different surface profiles in a region formed on the uneven layer (reference sign A in <FIG>) and in a region not on the uneven layer (reference sign B in <FIG>). The protective layer is in contact with the release layer, and it is preferable that its surface on the substrate side should have a profile complementary to that of the surface of the release layer described above.

A protective layer preferably includes a cured product of a curable resin composition. Examples of the cured product of the curable resin composition include the cured product of a thermosetting resin composition, the cured product of an ionizing radiation curable resin composition, and a cured product of a mixture thereof, and of these, the cured product of the ionizing radiation curable resin composition is preferable from the viewpoint of abrasion resistance of the protective layer. In addition, of the cured products of the ionizing radiation curable resin composition, the cured product of the electron beam curable resin composition is preferable from the viewpoints of easy completion of crosslinked hardening in formation of the protective layer.

The thermosetting resin composition is at least a composition including a thermosetting resin and is a resin composition that is cured by heating. Examples of the thermosetting resin include an acrylic resin, a urethane resin, a phenol resin, an urea melamine resin, an epoxy resin, an unsaturated polyester resin, and a silicone resin. For the thermosetting resin composition, a curing agent is added to these thermosetting resins as necessary.

Examples of the polyfunctional (meth)acrylate monomer include a (meth)acrylate monomer having two or more ionizing radiation curable functional groups in the molecule and having at least a (meth)acryloyl group as the functional group, and the acrylate monomer having an acryloyl group is preferable. These polymerizable oligomers may be used singly or in combination of two or more.

The number of functional groups of the polymerizable monomer is preferably <NUM> or more and <NUM> or less, more preferably <NUM> or more and <NUM> or less, still more preferably <NUM> or more and <NUM> or less, and particularly preferably <NUM> or more and <NUM> or less.

Examples of the polymerizable oligomer include a (meth)acrylate oligomer having two or more ionizing radiation curable functional groups in the molecule and having at least a (meth)acryloyl group as the functional group. Examples thereof include a urethane (meth)acrylate oligomer, an epoxy (meth)acrylate oligomer, a polyester (meth)acrylate oligomer, a polyether (meth)acrylate oligomer, a polycarbonate (meth)acrylate oligomer, and an acrylic (meth)acrylate oligomer.

These polymerizable oligomers may be used singly or in combination of two or more.

Of polymerizable oligomers, polycarbonate (meth)acrylate oligomers are preferable. The polycarbonate (meth)acrylate oligomer is not particularly limited as long as it has carbonate binding on the main chain and (meth)acrylate groups on the end or side chains, and may be a polycarbonate-based urethane (meth)acrylate oligomer that is a urethane (meth)acrylate oligomer having a polycarbonate skeleton.

For the ionizing radiation curable resin, a monofunctional (meth)acrylate can be used in combination as appropriate along with the above-described multifunctional (meth)acrylate or the like, for the purpose of reducing its viscosity or the like. These monofunctional (meth)acrylates may be used alone or in combination of plural kinds.

From the viewpoints of heat resistance and moldability, the weight average molecular weight of the monomer and oligomer used for a protective layer is preferably <NUM> or more and <NUM> or less, more preferably <NUM> or more and <NUM> or less, and still more preferably <NUM> or more and <NUM> or less.

It is preferable that the protective layer should contain substantially no particles such as organic particles and inorganic particles. When the protective layer does not contain particles, it is possible to make the pattern of the print layer, which will be the underlying layer, easily visible.

The phrase "substantially no particles contained in the protective layer" means that the particles are contained in an amount of <NUM>% by mass or less of the entire solid content of the protective layer, preferably <NUM>% by mass or less, more preferably <NUM>% by mass or less, and still more preferably <NUM>% by mass.

A protective layer may also further contain a thermoplastic resin as a resin component other than the cured product of the curable resin composition. The protective layer including the thermoplastic resin prevents cracking during molding and provides good moldability. Common resins such as an acrylic based resin, a polyester-based resin, and a urethane-based resin can be used for the thermoplastic resin.

The content of the thermoplastic resin is preferably <NUM> to <NUM>% by mass, more preferably <NUM> to <NUM>% by mass, and still more preferably <NUM> to <NUM>% by mass, with respect to the total solid content of the protective layer.

The thickness of a protective layer is preferably <NUM> to <NUM>, more preferably <NUM> to <NUM>, and still more preferably <NUM> to <NUM>, from the viewpoint of the balance between surface hardness and moldability.

A protective layer can be formed by a known printing method such as a gravure printing method, an offset printing method, a letterpress printing method, and a silk screen printing method.

A thermosetting resin composition and/or an ionizing radiation curable resin composition may be completely cured in forming a protective layer; however, from the viewpoint of moldability, the thermosetting resin composition and/or the ionizing radiation curable resin composition are uncured or semi-cured in forming the protective layer, are transferred to an adherend, and then may be progressively cured to result in complete curing.

A print layer is a layer for providing the desired design decorativeness to a decorative molded article.

The pattern of the print layer is arbitrary, for example, wood, stone, fabric, sand, circle, square, polygon, geometric patterns, characters, and solid printing.

A print layer preferably includes a binder resin such as a polyvinyl-based resin, a polyester-based resin, an acrylic based resin, a polyvinyl acetal-based resin, and a cellulose-based resin, and a pigment and/or a dye.

The thickness of the print layer is preferably <NUM> to <NUM>, and more preferably <NUM> to <NUM>, from the viewpoint of design decorativeness.

A print layer can be formed by a known printing method such as a gravure printing method, an offset printing method, a letterpress printing method, and a silk screen printing method.

An adhesive layer has a role to improve adhesiveness between the adherend such as a resin molded body and a transfer layer. When the adhesiveness between a protective layer and the adherend is good, no adhesive layer may be provided.

The resin having the adhesiveness suitable for the material of the adherend is preferably used for an adhesive layer. For example, when the adherend material is acrylic based resin, acrylic based resin is preferably used. In addition, when the material of the adherend is polyphenylene oxide/polystyrene based resin, polycarbonate-based resin, or styrene-based resin, it is preferable to use a resin having an affinity for these resins, for example, an acrylic based resin, a polystyrene-based resin, or a polyamide-based resin. Furthermore, when the material of the adherend is polypropylene resin, it is preferable to use a chlorinated polyolefin resin, a chlorinated ethylene-vinyl acetate copolymer resin, a cyclized rubber, or a coumarone-indene resin.

The adhesive layer may be formulated with an additive such as an ultraviolet absorber and an infrared absorber.

The thickness of the adhesive layer is preferably <NUM> to <NUM>, and more preferably <NUM> to <NUM>.

An adhesive layer can be formed by a known printing method such as a gravure printing method, an offset printing method, a letterpress printing method, and a silk screen printing method.

A primer layer is a layer that is provided as necessary to improve the adhesion between a protective layer and a print layer.

Preferably, a primer layer mainly includes a resin composition. In addition, in consideration of providing heat resistance, the resin component of the primer layer preferably includes a cured product of a curable resin composition, when placed in a high temperature environment such as in-mold molding.

Examples of the curable resin composition include a thermosetting resin composition and an ionizing radiation curable resin composition. As the thermosetting resin composition and the ionizing radiation curable resin composition of the primer layer, there can be used the same ones as those exemplified as the thermosetting resin composition and the ionizing radiation curable resin composition of the protective layer.

Particularly, the primer layer preferably includes the cured product of a thermosetting resin composition. Examples of the thermosetting resin composition include a two-component curable urethane resin including a various polyol compound such as a polyether polyol, a polyester polyol, and an acrylic polyol, and a curing agent such as an isocyanate compound.

The thickness of a primer layer is preferably <NUM> to <NUM>, and more preferably <NUM> to <NUM>.

The primer layer may have a single layer structure; however, it may also have a structure in which two or more layers are laminated, in consideration of, for example, adhesion between layers.

A primer layer can be formed by a known printing method such as a gravure printing method, an offset printing method, a letterpress printing method, and a silk screen printing method.

The decorative molded article produced by using the transfer sheet of the present invention will be described with reference to <FIG> is a schematic cross-sectional view of a decorative molded article. A decorative molded article <NUM> has an adherend <NUM> and a transfer layer <NUM> that covers the adherend. In <FIG>, the transfer layer <NUM> includes an adhesive layer <NUM>, a print layer <NUM>, a primer layer <NUM>, and a protective layer <NUM> in this order from the side of the adherend. The protective layer <NUM> is located on the outermost layer of the decorative molded article <NUM>.

An adherend is a resin molded body composed of resin. The shape of the adherend may be a flat shape or a three-dimensional shape having, for example, a curved surface. In addition, the adherend may be colored.

The resin molded body can be formed from a thermoplastic resin or thermosetting resin.

When a decorative molded article is produced by in-mold molding, it is preferable to use a thermoplastic resin as the resin molded article. Examples of these thermoplastic resins include a polystyrene-based resin, a polyolefin-based resin, an ABS resin (including a heat resistant ABS resin), an AS resin, a PC/ABS based resin, a PC/AS based resin, an AN resin, a polyphenylene oxide based resin, a polycarbonate-based resin, a polyacetal-based resin, an acrylic based resin, a polyethylene terephthalate based resin, a polybutylene terephthalate based resin, a polysulfone based resin, and a polyphenylene sulfide based resin.

It is preferable that the protective layer in the decorative molded article of the present invention should have an uneven profile that is approximately complementary to the surface profile of the release layer of the release sheet. This uneven profile is the profile corresponding to the pattern of the uneven layer. For example, the surface of the protective layer has a minute uneven profile at the point corresponding to the uneven layer (reference sign A' in <FIG>). Therefore, the point corresponding to the uneven layer (reference sign A' in <FIG>) is a region with a low gloss that has a matting effect compared to its surroundings (reference sign B' in <FIG>). That is, the decorative molded article of the present invention has a pattern with a gloss difference in the surface. In the present invention, the region of the reference sign B' does not necessarily need to be glossy. As long as the region of reference sign B' is glossier than the region of reference sign A' and the gloss difference is clear, the region B' may have a matting effect.

A method for producing a decorative molded article of the present invention comprises: (<NUM>) a step of adhering the transfer layer of the transfer sheet to an adherend via an adhesive layer, thereby laminating the transfer sheet on the adherend; and (<NUM>) a step of peeling off the release sheet of the transfer sheet to transfer the transfer layer on the adherend.

The transfer sheet of the present invention is particularly preferably applied to the produce of the decorative molded article by in-mold molding (injection molding simultaneous transfer decoration method). According to the present invention, it is possible to transfer a pattern having a gloss difference on the surface of a resin molded product having a complicated surface profile such as a three dimensional curved surface.

One embodiment of the method of producing a decorative molded article by in-mold molding has the following steps:.

In the present invention, the binder resin of the uneven layer is a thermoplastic resin, which provides excellent adhesiveness between the release layer and the uneven layer. Therefore, when the release sheet is peeled off in producing the decorative molded article, peeling at the interface between the uneven layer and the release layer can be prevented and the peel strength can also be made approximately uniform. As a result, the occurrence of a defective transfer can be suppressed.

Then, the present invention will be described in more detail by Examples; however, the present invention is not limited to these examples.

The atmosphere of the following measurement and evaluation was a temperature of <NUM> ± <NUM> and a humidity of <NUM> to <NUM>%. In addition, a target sample was exposed to the atmosphere for <NUM> minutes or more, and measurement and evaluation were performed.

For the decorative molded articles produced in Examples and Comparative Examples, the presence or absence of the gloss difference between the region with the uneven layer and the region without the uneven layer was evaluated in accordance with the following criteria.

Twenty subjects made evaluations, and the average point was calculated. The design decorativeness of each decorative molded article was evaluated in accordance with the following criteria.

For each of the transfer sheets of Examples and Comparative Examples, the release sheet was peeled off from the transfer sheet. Those in which the release sheet was easily peeled off and the release layer did not remain on the transfer layer side were given <NUM> points, those in which the release sheet was difficult to be peeled off but the release layer did not remain on the transfer layer side were given <NUM> point, and those in which the release sheet was difficult to be peeled off and the release layer was observed to remain on the transfer layer were given <NUM> points. Evaluation of peelability was performed on <NUM> release sheets, and the average point was calculated. The peelability of each transfer sheet was evaluated in accordance with the following criteria.

Coating liquids for uneven layer having the following formulations were produced.

Coating liquids for release layer having the following formulations were produced.

A coating liquid for protective layer having the following formulation was produced.

A coating liquid for primer layer having the following formulation was produced.

On one side of a substrate (biaxially stretched polyethylene terephthalate film with a thickness of <NUM>), the coating liquid for uneven layer <NUM> was applied and dried to form an uneven layer with a thickness of <NUM>. The uneven layer was made to have a wood conduit pattern.

Then, the coating liquid for release layer <NUM> was applied on the substrate and on the uneven layer, and irradiated with electron beams under conditions of <NUM> KeV and <NUM> Mrad (<NUM> kGy) to form a release layer with a thickness of <NUM>.

Then, the coating liquid for a protective layer was applied onto the release layer, and an electron beam was irradiated under the conditions of <NUM> KeV and <NUM> Mrad (<NUM> kGy) to form the protective layer having a thickness of <NUM>.

Then, the coating liquid for a primer layer <NUM> was applied onto the protective layer and dried to form the primer layer having a thickness of <NUM>.

Then, brown ink (acrylic based resin composition) was applied onto the primer layer by using a gravure printing method and dried to form the wood-pattern print layer having a thickness of <NUM>.

Then, a thermoplastic resin (acrylic based resin) had been diluted with a solvent and the resultant coating liquid for an adhesive layer was applied onto the print layer and dried to be formed into the <NUM> thick adhesive layer having heat sealing properties. The transfer sheet of Example <NUM> was obtained by the steps described above.

The transfer sheet of Example <NUM> was produced by the same steps as in Example <NUM>, except that the coating liquid for uneven layer <NUM> was used.

The transfer sheet of Example <NUM> was produced by the same steps as in Example <NUM>, except that the coating liquid for release layer <NUM> was used.

The transfer sheet of Example <NUM> was produced by the same steps as in Example <NUM>, except that the thickness of the release layer was changed to <NUM>.

As the coating liquid for uneven layer of Comparative Example <NUM>, a coating liquid containing a thermosetting resin having the following formulation was prepared.

On one side of a substrate (biaxially stretched polyethylene terephthalate film with a thickness of <NUM>), the coating liquid for uneven layer of Comparative Example <NUM> was applied and dried. As in Example <NUM>, the uneven layer was formed on a portion of the substrate. It was then cured by aging at <NUM> for <NUM> hours to form an uneven layer with a thickness of <NUM>, and a release layer with a thickness of <NUM> was formed. The other layers were formed in the same manner as in Example <NUM>, thereby obtaining the transfer sheet of Comparative Example <NUM>.

The transfer sheet of Comparative Example <NUM> was obtained by the same steps as in Example <NUM>, except that no uneven layer was provided.

Each of the transfer sheets of Examples <NUM> to <NUM> and Comparative Examples <NUM> and <NUM> was arranged on one side of a pair of upper and lower in-mold molding dies. An adhesive layer was arranged so as to face the inside of the die (the side in contact with an injection resin).

Then, the die was tightened, the injection resin (PC/ABS resin) was injected into the die to provide a laminate (plate-shaped body having <NUM> × <NUM> × <NUM> thick) in which the transfer sheet and the injection resin layer including the injection resin were integrated with each other.

Then, the die was opened, and then the transfer sheet (substrate to release layer) was peeling off from the laminate to provide the decorative molded articles of Examples <NUM> to <NUM> and Comparative Examples <NUM> and <NUM>.

The evaluation results of the transfer sheets and the decorative molded articles of Examples and Comparative Examples are shown in Table <NUM>.

The transfer sheets of Examples <NUM> to <NUM>, in which thermoplastic resins were used for the uneven layer, all had good peelability. In particular, for the decorative molded articles of Examples <NUM> to <NUM>, the gloss difference in the surface was clear and the design decorativeness was good. The design decorativeness of the decorative molded articles of Examples <NUM> to <NUM> was inferior to that of Examples <NUM> to <NUM>, but was not a problem in use.

Claim 1:
A transfer sheet (<NUM>) comprising a transfer layer (<NUM>) on a release sheet (<NUM>),
wherein the release sheet (<NUM>) comprises:
a substrate (<NUM>);
an uneven layer (<NUM>) provided on a portion of one surface of the substrate and containing a matting agent and a binder resin comprising a thermoplastic resin, wherein the uneven layer (<NUM>) contains the matting agent in an amount of <NUM> parts by mass or more and <NUM> parts by mass or less based on <NUM> parts by mass of the binder resin, and wherein the proportion of the thermoplastic resin in the binder resin is <NUM>% or more; and
a release layer (<NUM>) provided on the uneven layer (<NUM>) and on a portion of the substrate where the uneven layer is not formed.