JP7635528B2 - Transfer sheet and method for manufacturing a member using said transfer sheet - Google Patents

Description

The present invention relates to a transfer sheet and a method for manufacturing a component using the transfer sheet.

2. Description of the Related Art In the fields of household electrical appliances, automobile interior parts, miscellaneous goods, and the like, there are cases where the surfaces of articles are decorated or surface protective layers are formed by transfer printing methods.
The transfer method is a method in which a transfer sheet having a transfer layer formed on a substrate, which comprises a release layer, a surface protection layer, a design layer, an adhesive layer, etc., is adhered to an article to which the transfer is to be made, and then the substrate is peeled off and only the transfer layer is transferred to the surface of the article to which the transfer is to be made, thereby decorating the article.

As a transfer sheet for decorating the surface of an article, Patent Document 1 proposes a design transfer sheet including a design transfer layer releasably attached to a release layer.
Furthermore, Patent Document 2 proposes a protective layer transfer sheet in which a transfer layer having a protective layer is formed on a substrate that is easily deformed by heat, as a transfer sheet for forming a protective layer on the surface of an article for the purpose of preventing scratches on the molded product, etc.

JP 2016-120643 A JP 2005-297460 A

However, when the transfer sheets of Patent Documents 1 and 2 are used outdoors, etc., the patterns and other designs applied to the articles tend to fade due to the effects of ultraviolet rays from sunlight, making it difficult to maintain the applied designs for a long period of time.
Furthermore, in the transfer sheets of Patent Documents 1 and 2, the protective layer and other layers are easily deteriorated due to the effects of ultraviolet rays from sunlight, etc., and it is difficult to maintain the functionality of the protective layer and other layers for a long period of time, particularly when used outdoors.

The present invention was made in consideration of these circumstances, and aims to provide a transfer sheet having a surface protective layer that improves the weather resistance of an article when used outdoors for a long period of time, and a method for manufacturing a member that has excellent weather resistance when used outdoors for a long period of time.

In order to solve the above problems, the present invention provides the following <1> to <4>.
<1> A transfer sheet having a transfer layer on a release film, the transfer layer having a surface protection layer, a primer layer and an adhesive layer in this order from the release film side, the surface protection layer containing an ultraviolet absorber, the total content of the ultraviolet absorber per 100 parts by mass of resin forming the surface protection layer being 10 parts by mass or less, and the surface protection layer satisfying the following [1] or [2].
[1] The composition contains, as an ultraviolet absorber, a hydroxyphenyl triazine compound represented by the following general formula (I) and a hydroxyphenyl triazine compound represented by the following general formula (II), and the content of the hydroxyphenyl triazine compound represented by the following general formula (II) is 50 mass% or less relative to the total content of the hydroxyphenyl triazine compound represented by the following general formula (I) and the content of the hydroxyphenyl triazine compound represented by the following general formula (II) is 100 mass%.
[2] The composition contains a hydroxyphenyltriazine compound represented by the following general formula (I) and a hydroxyphenyltriazine compound represented by the following general formula (III) as an ultraviolet absorbing agent.



<2> The transfer sheet according to <1>, wherein the adhesive layer contains a colorant.
<3> The transfer sheet according to <1> or <2>, further comprising a decorative layer between the adhesive layer and the primer layer.
<4> A method for manufacturing a component, comprising the following steps (1) and (2) in order:
(1) A step of bringing the surface of the transfer layer side of the transfer sheet according to any one of items (1) to (3) into close contact with an adherend.
(2) A step of peeling off the release film of the transfer sheet from the tightly attached transfer sheet and adherend.

The objective of the present invention is to provide a transfer sheet having a surface protective layer that improves the weather resistance of an article when used outdoors for a long period of time, and a method for manufacturing a member that has excellent weather resistance when used outdoors for a long period of time.

1 is a cross-sectional view showing one embodiment of a transfer sheet of the present invention. FIG. 2 is a cross-sectional view showing another embodiment of the transfer sheet of the present invention.

[Transfer sheet]
The transfer sheet of the present invention has a transfer layer on a release film, and the transfer layer has, from the release film side, a surface protection layer, a primer layer and an adhesive layer in this order, the surface protection layer contains an ultraviolet absorber, the total content of the ultraviolet absorber per 100 parts by mass of resin forming the surface protection layer is 10 parts by mass or less, and the surface protection layer is characterized in that it satisfies the following [1] or [2].
[1] The composition contains a hydroxyphenyltriazine compound represented by the above general formula (I) and a hydroxyphenyltriazine compound represented by the above general formula (II) as an ultraviolet absorber, and the content of the hydroxyphenyltriazine compound represented by the above general formula (II) is 50 mass% or less relative to the total content of the hydroxyphenyltriazine compound represented by the above general formula (I) and the content of the hydroxyphenyltriazine compound represented by the above general formula (II) being 100 mass%.
[2] The composition contains, as an ultraviolet absorbing agent, a hydroxyphenyltriazine compound represented by the above general formula (I) and a hydroxyphenyltriazine compound represented by the above general formula (III).

Figure 1 is a cross-sectional view showing one embodiment of the transfer sheet of the present invention. The transfer sheet 10 in Figure 1 has a transfer layer 11 on a release film 1. The transfer layer 11 has, in order from the side in contact with the release film 1, a surface protection layer 2, a primer layer 3, and an adhesive layer 4.

Figure 2 is a cross-sectional view showing another embodiment of the transfer sheet of the present invention. The transfer sheet 10 in Figure 2 has a transfer layer 11 on a release film 1. The transfer layer 11 has, in order from the side in contact with the release film 1, a surface protection layer 2, a primer layer 3, a decorative layer 5, and an adhesive layer 4.

Although not shown in FIGS. 1 and 2, the transfer sheet 10 may further have a second release film on the surface of the adhesive layer 4 opposite to the release film 1, if necessary.
Although not shown in FIGS. 1 and 2, the transfer layer 11 may further have other functional layers as necessary.

In the transfer sheet 10 shown in Figures 1 and 2, the surface protective layer 2 contains an ultraviolet absorbing agent, and the total content of the ultraviolet absorbing agent per 100 parts by mass of the resin forming the surface protective layer 2 is 10 parts by mass or less. In addition, the surface protective layer 2 satisfies the above [1] or [2]. Therefore, when the transfer layer is transferred to an adherend to form a member, the weather resistance of the member can be improved.

[Release film]
The release film is a layer that is laminated releasably on the transfer layer among the layers that constitute the transfer sheet. The release film is peeled off from the transfer layer after the transfer layer is transferred to an adherend such as a resin sheet.

The release film is preferably a plastic film that can be peelably laminated with the transfer layer and has heat resistance in order to improve the processability of the transfer sheet in the transfer step.
Examples of plastic films used as release films include polyester resins such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate; polyamide resins such as nylon 6 and nylon 66; and polyimide resins. Of these, it is preferable to use polyester resins, and among polyester resins, it is particularly preferable to use polyethylene terephthalate.

The thickness of the release film is not particularly limited, but in order to improve the handleability of the transfer sheet, it is preferably from 10 μm to 200 μm, more preferably from 15 μm to 150 μm, and even more preferably from 20 μm to 100 μm.

[Transfer Layer]
The transfer layer of the present invention is a layer that is transferred to an adherend, and has the role of imparting a predetermined function to the surface of the adherend.
The transfer layer of the transfer sheet of the present invention has at least a surface protective layer, a primer layer and an adhesive layer in this order from the release film side. In addition, the transfer layer of the transfer sheet preferably further has a decorative layer in order to impart design to the member.

The transfer layer may further include other functional layers. Examples of the other functional layers include an antiglare layer, an antifouling layer, a stress relaxation layer, an antistatic layer, a gas barrier layer, an antifogging layer, and a transparent conductive layer.

(Surface protection layer)
The transfer sheet of the present invention has a surface protective layer on the transfer layer. The surface protective layer in the present invention is a layer formed to impart durability, such as weather resistance, to the transfer layer of the transfer sheet of the present invention. Other durability required for the surface protective layer includes resistance to contamination by various substances such as mud, scratch resistance, etc.

The surface protective layer in the present invention must contain a total ultraviolet absorber in a content of 10 parts by mass or less relative to 100 parts by mass of the resin forming the surface protective layer. If the content of the ultraviolet absorber exceeds 10 parts by mass, bleeding out is likely to occur, and the strength of the surface protective layer may decrease, so that the transfer layer of the transfer sheet cannot be provided with long-term weather resistance. The upper limit of the content of the total ultraviolet absorber contained in the surface protective layer is preferably 9 parts by mass or less, more preferably 7 parts by mass or less, even more preferably 5 parts by mass or less, and particularly preferably 4 parts by mass or less, relative to 100 parts by mass of the resin forming the surface protective layer. There is no particular restriction on the lower limit of the content of the total ultraviolet absorber contained in the surface protective layer as long as it can provide weather resistance to the transfer layer of the transfer sheet, but in order to provide long-term weather resistance to the transfer layer of the transfer sheet, it is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, and even more preferably 1 part by mass or more, relative to 100 parts by mass of the resin forming the surface protective layer.
The above "total ultraviolet absorbers" in the surface protective layer refers to all ultraviolet absorbers contained in the surface protective layer, including the hydroxyphenyltriazine compounds represented by the general formula (I), the general formula (II), and the general formula (III).

The surface protective layer in the present invention is required to contain a hydroxyphenyltriazine compound represented by the above general formula (I) and a hydroxyphenyltriazine compound represented by the above general formula (II) or (III).
If the surface protective layer of the present invention does not contain the hydroxyphenyl triazine compound represented by the above general formula (I) and the hydroxyphenyl triazine compound represented by the above general formula (II) or the above general formula (III), the transfer layer of the transfer sheet cannot be provided with long-term weather resistance. In order to easily provide the transfer layer of the transfer sheet with better bleed-out resistance and long-term weather resistance, it is more preferable that the surface protective layer contains a combination of the hydroxyphenyl triazine compound represented by the above general formula (I) and the hydroxyphenyl triazine compound represented by the above general formula (III).
As long as the effects of the present invention are not impaired, the three types of hydroxyphenyltriazine compounds represented by the general formulas (I), (II) and (III) can be used in combination. However, it is difficult to obtain the effects of bleed-out resistance and long-term weather resistance that exceed those obtained by the combination of the above-mentioned two types of compounds.

In the surface protective layer of the present invention, when the hydroxyphenyl triazine compound represented by the general formula (I) and the hydroxyphenyl triazine compound represented by the general formula (II) are used as the ultraviolet absorber, the content of the hydroxyphenyl triazine compound represented by the general formula (II) must be 50% by mass or less relative to the total 100% by mass of the content of the hydroxyphenyl triazine compound represented by the general formula (I) and the content of the hydroxyphenyl triazine compound represented by the general formula (II). If the content of the hydroxyphenyl triazine compound represented by the general formula (II) exceeds 50% by mass, the bleed-out resistance is poor and long-term weather resistance cannot be achieved.
The upper limit of the content of the hydroxyphenyl triazine compound shown in the general formula (II) relative to the total 100% by mass of the content of the hydroxyphenyl triazine compounds shown in the general formula (I) and the general formula (II) is preferably 45% by mass or less, more preferably 40% by mass or less, in order to easily suppress the bleeding out of the ultraviolet absorber and to easily impart long-term weather resistance to the transfer layer of the transfer sheet. The lower limit of the content of the hydroxyphenyl triazine compound shown in the general formula (II) is not particularly limited as long as it can suppress the bleeding out of the ultraviolet absorber and impart long-term weather resistance to the transfer layer of the transfer sheet, but since the hydroxyphenyl triazine compound shown in the general formula (I) alone cannot fully absorb the entire wavelength range of ultraviolet light, it is preferable to add an appropriate amount of the hydroxyphenyl triazine compound shown in the general formula (II) whose ultraviolet absorption wavelength range is complementary to that of the hydroxyphenyl triazine compound shown in the general formula (I) in order to easily impart long-term weather resistance to the transfer layer of the transfer sheet against the entire substrate made of various materials. Therefore, in order to impart long-term weather resistance to the transfer layer of the transfer sheet, the content of the hydroxyphenyltriazine compound represented by the above general formula (II) is preferably 1 mass % or more, more preferably 5 mass % or more, and even more preferably 10 mass % or more.

In the surface protective layer of the present invention, when the hydroxyphenyl triazine compound shown in the general formula (I) and the hydroxyphenyl triazine compound shown in the general formula (III) are used as the ultraviolet absorber, the content of the hydroxyphenyl triazine compound shown in the general formula (III) relative to the total 100% by mass of the content of the hydroxyphenyl triazine compound shown in the general formula (I) and the content of the hydroxyphenyl triazine compound shown in the general formula (III) is not particularly limited as long as it can suppress the bleeding out of the ultraviolet absorber and impart long-term weather resistance to the transfer layer of the transfer sheet. However, since the hydroxyphenyl triazine compound shown in the general formula (I) alone cannot fully absorb the entire wavelength range of ultraviolet rays, it is preferable to also add an appropriate amount of the hydroxyphenyl triazine compound shown in the general formula (III) whose ultraviolet absorption wavelength range is complementary to that of the hydroxyphenyl triazine compound shown in the general formula (I) in order to easily impart better weather resistance to substrates made of various materials when used outdoors for long periods of time. Therefore, in order to impart excellent weather resistance to the transfer layer of the transfer sheet, the content of the hydroxyphenyltriazine compound represented by the above general formula (III) is preferably 95% by mass or less, more preferably 90% by mass or less. In addition, the lower limit of the content of the hydroxyphenyltriazine compound represented by the above general formula (III) is not particularly limited as long as it can suppress the bleeding out of the ultraviolet absorber and impart long-term weather resistance to the transfer layer of the transfer sheet, but in order to impart long-term weather resistance to the transfer layer of the transfer sheet as described above, it is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more.

The reason why the use of the hydroxyphenyltriazine compound represented by the above general formula (III) can impart long-term weather resistance to the transfer layer of the transfer sheet is believed to be because the molecule does not contain a structure such as an ester bond that is likely to become the starting point for decomposition or mutation of the molecular structure when used outdoors. Since the molecule does not contain a structure such as an ester bond, decomposition or mutation of the molecular structure is less likely to occur, making it easier to suppress bleed-out, and long-term weather resistance can be imparted to the transfer layer of the transfer sheet. Furthermore, due to the above characteristics, even if the content of the hydroxyphenyltriazine compound represented by the above general formula (III) in the surface protection layer is small, good weather resistance can be imparted to the transfer layer of the transfer sheet.

The surface protective layer of the present invention may contain an ultraviolet absorber other than the hydroxyphenyltriazine compounds shown in the general formula (I), the general formula (II) and the general formula (III) above, within a range that does not impair the effects of the present invention. The total content ratio of the hydroxyphenyltriazine compounds shown in the general formula (I) and the general formula (II) above and the total content ratio of the hydroxyphenyltriazine compounds shown in the general formula (I) and the general formula (III) above to the total ultraviolet absorbers contained in the surface protective layer are preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more.

In order to improve scratch resistance, the surface protective layer of the present invention preferably contains a cured product of a curable resin composition as a resin component. The ratio of the cured product of the curable resin composition to the total resin components constituting the surface protective layer is preferably 70% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 100% by mass.

Examples of the cured product of the curable resin composition include a cured product of a thermosetting resin composition or a cured product of an ionizing radiation curable resin composition. Among these, it is preferable to use a cured product of an ionizing radiation curable resin composition in order to improve the scratch resistance of the surface resin layer and the processability of the transfer sheet.

Thermosetting resin compositions are compositions that contain at least a thermosetting resin, and are resin compositions that are cured by heating. Examples of thermosetting resins include acrylic resins, urethane resins, urethane acrylic resins, phenolic resins, urea melamine resins, epoxy resins, unsaturated polyester resins, and silicone resins. These can be used alone or in combination. The thermosetting resin composition may also be one in which a curing agent such as an isocyanate-based curing agent or an epoxy-based curing agent is added to these resins. Among these, acrylic resins are preferred, and acrylic resins with an isocyanate curing agent added are more preferred.

Representative examples of ionizing radiation curable resin compositions include electron beam curable resin compositions and ultraviolet ray curable resin compositions. Among these, electron beam curable resin compositions are preferred because they do not require a polymerization initiator, have less odor, and are less prone to coloring. In addition, electron beam curable resin compositions are preferred because the surface protective layer contains an ultraviolet ray absorber, making it easier to increase the crosslink density of the cured layer and improve scratch resistance and contamination resistance.

The ionizing radiation curable resin composition is a composition containing a compound having an ionizing radiation curable functional group (hereinafter also referred to as "ionizing radiation curable compound"). The ionizing radiation curable functional group is a group that crosslinks and cures by irradiation with ionizing radiation, and preferred examples thereof include functional groups having an ethylenic double bond such as a (meth)acryloyl group, a vinyl group, and an allyl group. In this specification, the (meth)acryloyl group refers to an acryloyl group or a methcroyl group. In addition, in this specification, the (meth)acrylate refers to an acrylate or a methacrylate.
In addition, ionizing radiation refers to electromagnetic waves or charged particle beams that have an energy quantum capable of polymerizing or crosslinking molecules. Usually, ultraviolet rays (UV) or electron beams (EB) are used, but other examples include electromagnetic waves such as X-rays and gamma rays, and charged particle beams such as alpha rays and ion beams.
Specifically, the ionizing radiation curable compound can be appropriately selected from polymerizable monomers and polymerizable oligomers that have been conventionally used as ionizing radiation curable resins.

As the polymerizable monomer, a (meth)acrylate monomer having a radically polymerizable unsaturated group in the molecule is preferable, and among them, a polyfunctional (meth)acrylate monomer is preferable. Here, "(meth)acrylate" means "acrylate or methacrylate".
The polyfunctional (meth)acrylate monomer includes 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.
In order to improve the processing characteristics of the transfer sheet and the scratch resistance and weather resistance of the surface protective layer, the number of functional groups of the polyfunctional (meth)acrylate monomer is preferably from 2 to 8, more preferably from 2 to 6, even more preferably from 2 to 4, and even more preferably from 2 to 3. These polyfunctional (meth)acrylates may be used alone or in combination of two or more kinds.

Examples of the polymerizable oligomer include (meth)acrylate oligomers having two or more ionizing radiation-curable functional groups in the molecule and having at least a (meth)acryloyl group as the functional group, such as urethane (meth)acrylate oligomers, epoxy (meth)acrylate oligomers, polyester (meth)acrylate oligomers, polyether (meth)acrylate oligomers, polycarbonate (meth)acrylate oligomers, and acrylic (meth)acrylate oligomers.
Further examples of the polymerizable oligomer include highly hydrophobic polybutadiene (meth)acrylate oligomers having (meth)acrylate groups in the side chains of polybutadiene oligomers, silicone (meth)acrylate oligomers having polysiloxane bonds in the main chains, aminoplast resin (meth)acrylate oligomers obtained by modifying aminoplast resins having many reactive groups in a small molecule, and oligomers having cationically polymerizable functional groups in the molecule, such as novolac type epoxy resins, bisphenol type epoxy resins, aliphatic vinyl ethers, and aromatic vinyl ethers.

These polymerizable oligomers may be used alone or in combination. In order to improve the processing characteristics of the transfer sheet and the scratch resistance and weather resistance of the surface protective layer, one or more selected from 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 are preferred, one or more selected from urethane (meth)acrylate oligomer and polycarbonate (meth)acrylate oligomer are more preferred, and urethane (meth)acrylate oligomer is even more preferred.

In order to improve the processing characteristics of the transfer sheet and the scratch resistance and weather resistance of the surface protective layer, the number of functional groups of these polymerizable oligomers is preferably 2 or more and 8 or less, with the upper limit being more preferably 6 or less, even more preferably 4 or less, and even more preferably 3 or less.
In addition, the weight average molecular weight of these polymerizable oligomers is preferably 2,500 or more and 7,500 or less, more preferably 3,000 or more and 7,000 or less, and even more preferably 3,500 or more and 6,000 or less, in order to improve the processability of the transfer sheet and the scratch resistance and weather resistance of the surface protective layer.
In this specification, the weight average molecular weight is an average molecular weight measured by GPC analysis and converted into standard polystyrene.

In the ionizing radiation curable resin composition, monofunctional (meth)acrylates can be used in combination for the purpose of reducing the viscosity of the ionizing radiation curable resin composition. These monofunctional (meth)acrylates may be used alone or in combination of two or more types.

When the ionizing radiation curable compound is an ultraviolet ray curable compound, it is preferable to contain additives such as a photopolymerization initiator and a photopolymerization accelerator.
The photopolymerization initiator may be one or more selected from acetophenone, benzophenone, α-hydroxyalkylphenone, Michler's ketone, benzoin, benzyl dimethyl ketal, benzoyl benzoate, α-acyloxime ester, acylphosphine oxide, thioxanthones, and the like.
The photopolymerization accelerator can reduce polymerization inhibition caused by air during curing and increase the curing speed, and examples of the accelerator include one or more types selected from p-dimethylaminobenzoic acid isoamyl ester, p-dimethylaminobenzoic acid ethyl ester, and the like.

The surface protective layer may contain other additives as necessary, as long as the effects of the present invention are not impaired. As other additives, it is preferable to use, for example, antioxidants, light stabilizers, organic particles, inorganic particles, etc.

The thickness of the surface protective layer is preferably 1.5 μm or more and 30 μm or less, more preferably 2 μm or more and 20 μm or less, and even more preferably 3 μm or more and 15 μm or less, in order to improve the processing characteristics of the transfer sheet and the scratch resistance and weather resistance of the surface protective layer.

(Primer layer)
The transfer sheet of the present invention has a primer layer in the transfer layer. The primer layer is formed between the above-mentioned surface protective layer and the adhesive layer described below. By forming the primer layer between the surface protective layer and the adhesive layer, it is possible to improve the adhesion between the layers contained in the transfer layer, and to improve the weather resistance and durability of the transfer layer.

The primer layer preferably contains a cured product of a curable resin composition to improve the processability of the transfer sheet and the adhesion between the layers contained in the transfer layer.

As the cured product of the curable resin composition contained in the primer layer, the cured product of the curable resin composition exemplified in the above-mentioned surface protection layer can be used. Among them, in order to improve the adhesion between the layers contained in the transfer layer, it is preferable to contain a cured product of a thermosetting resin composition, and among these, a cured product of a thermosetting resin composition containing an acrylic resin, a urethane resin, or a urethane acrylic resin is more preferable, and a cured product of a thermosetting resin composition in which an acrylic resin, a urethane resin, or a urethane acrylic resin is crosslinked and cured with an isocyanate curing agent is even more preferable.

The primer layer may contain other additives as necessary, as long as the effect of the present invention is not impaired. As the other additives, for example, ultraviolet absorbers, antioxidants, light stabilizers, organic particles, inorganic particles, etc. are preferably used. In addition, as the ultraviolet absorbers, the ultraviolet absorbers presented in the above-mentioned surface protection layer can be suitably used.

The thickness of the primer layer is preferably 1 μm or more and 10 μm or less, more preferably 2 μm or more and 8 μm or less, and even more preferably 3 μm or more and 6 μm or less, in order to improve the processability of the transfer sheet and the adhesion between the layers contained in the transfer layer.

(Adhesive Layer)
The adhesive layer is a layer that is in contact with an adherend and is formed, for example, to improve adhesion with the adherend, among the layers that constitute the transfer layer of the transfer sheet.

The adhesive layer may be a pressure-sensitive adhesive layer, a curable adhesive layer, or a heat-sensitive adhesive layer, and among these, a heat-sensitive adhesive layer is preferred in order to improve the processability of the transfer sheet and the adhesion between the transfer layer of the transfer sheet and the adherend.

When the adhesive layer is a pressure-sensitive adhesive layer, it is preferred that the adhesive layer contains a pressure-sensitive adhesive.
The adhesive may be appropriately selected from acrylic, urethane, silicone, rubber, and other adhesives.

When the adhesive layer is a curable adhesive layer, it is preferable that the adhesive layer contains a thermosetting adhesive.
The thermosetting adhesive is preferably one that contains a composition that has the property of crosslinking due to a chemical reaction caused by heat, and examples of such adhesives include two-component curing urethane adhesives, polyester urethane adhesives, polyether urethane adhesives, acrylic adhesives, polyester adhesives, polyamide adhesives, polyvinyl acetate adhesives, epoxy adhesives, rubber adhesives, etc. The urethane resin that constitutes the two-component curing urethane adhesive is a polyurethane that uses polyol (polyhydric alcohol) as the main component and isocyanate as the crosslinking agent (curing agent).

When the adhesive layer is a heat-sensitive adhesive layer, it is preferable that the adhesive layer contains a thermoplastic resin.
Examples of thermoplastic resins include acrylic resins, urethane resins, vinyl chloride resins, vinyl acetate resins, vinyl chloride-vinyl acetate copolymers, styrene-acrylic copolymers, polyester resins, amide resins, cyanoacrylate resins, epoxy resins, etc., which can be used alone or in combination of two or more. Among these, it is preferable to use acrylic resins in order to improve the processability when forming a member using the transfer sheet and the adhesion between the transfer layer of the transfer sheet and the adherend.

The weight average molecular weight of the thermoplastic resin is preferably 10,000 or more and 200,000 or less, preferably 50,000 or more and 150,000 or less, and more preferably 80,000 or more and 120,000 or less. When the weight average molecular weight of the thermoplastic resin composition is within the above range, the coating suitability is improved, and the adhesive layer is easily formed in a good condition. Furthermore, when a member is manufactured using the transfer sheet of the present invention, the adhesion between the adhesive layer and the adherend is easily improved, and the durability of the member can be easily improved.

The thickness of the adhesive layer is preferably 1 μm or more and 10 μm or less, more preferably 2 μm or more and 8 μm or less, and even more preferably 3 μm or more and 7 μm or less. When the thickness of the adhesive layer is within the above range, it is easier to improve the adhesion between the adhesive layer and the adherend when forming the member.

The transfer sheet of the present invention preferably contains a colorant in the adhesive layer.
By including a colorant in the adhesive layer, the adhesive layer alone or in combination with a decorative layer (described later) can impart design properties to the transfer layer of the transfer sheet.

There are no particular limitations on the coloring agent, and examples include inorganic pigments such as carbon black (ink), iron black, titanium white, antimony white, yellow lead, titanium yellow, red iron oxide, cadmium red, ultramarine blue, and cobalt blue; organic pigments or dyes such as quinacridone red, isoindolinone yellow, nickel azo complex, phthalocyanine blue, and azomethine azo black; metal pigments such as scaly flakes of aluminum, brass, and the like; and pearlescent pigments such as scaly flakes of titanium dioxide-coated mica and basic lead carbonate, and the like.

The content of the colorant is preferably 5 parts by mass or more and 90 parts by mass or less, more preferably 15 parts by mass or more and 80 parts by mass or less, and even more preferably 20 parts by mass or more and 70 parts by mass or less, relative to 100 parts by mass of the resin constituting the decorative layer.
By making the content of the colorant 5 parts by mass or more, it is possible to easily impart design to the transfer layer of the transfer sheet. Also, by making the content of the colorant 90 parts by mass or less, it is possible to easily suppress the decrease in adhesion between the adhesive layer and the adherend caused by the addition of the colorant, and it is possible to easily form a transfer layer having a higher durability when a member is formed.

(Decorative layer)
In order to improve the design, the transfer sheet of the present invention preferably has a decorative layer at any position on the transfer layer of the transfer sheet.
The location where the decorative layer is formed is preferably between the adhesive layer and the primer layer, or between the primer layer and the surface protection layer, in order to improve the weather resistance of the decorative layer, and more preferably between the adhesive layer and the primer layer in order to further improve the durability of the transfer layer.

The decorative layer may be formed over the entire surface of the transfer sheet, or only on a portion of it.

Examples of the decorative layer include a colored layer formed by applying ink in a solid manner; a pattern layer formed by printing ink as a pattern; and a thin metal film.
Examples of patterns (designs) that can be expressed by the decorative layer include wood grain patterns such as annual rings and vascular grooves on the surface of a wooden board; stone grain patterns on the surface of stone slabs such as marble and granite; fabric grain patterns on the surface of fabric; leather grain patterns on the surface of leather; tile patterns including grooves in the joints; brickwork patterns including grooves in the joints; sand grain patterns; pear-skin patterns; patterns consisting of an arrangement of multiple concave and convex ridges extending in parallel directions (so-called ``line-like concave and convex patterns'' or ``ray-carved patterns''); and abstract patterns such as geometric patterns, letters, figures, polka dots, and floral patterns.

The ink used for the colored layer and the design layer is a suitable mixture of a binder resin, a colorant such as a pigment or dye, an extender pigment, a solvent, a stabilizer, a plasticizer, a catalyst, a hardener, an ultraviolet absorber, a light stabilizer, etc.
The binder resin for the colored layer and the design layer is not particularly limited, and examples thereof include urethane resin, acrylic polyol resin, acrylic resin, ester resin, amide resin, butyral resin, styrene resin, urethane-acrylic copolymer, vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-vinyl acetate-acrylic copolymer resin, chlorinated propylene resin, nitrocellulose resin, cellulose acetate resin, etc. In addition, various types of resins can be used, such as one-component curing resins and two-component curing resins accompanied by a curing agent such as an isocyanate compound.

The colorant is not particularly limited, and the colorants exemplified for the adhesive layer described above can be suitably used.
The content of the colorant is preferably 5 parts by mass or more and 90 parts by mass or less, more preferably 15 parts by mass or more and 80 parts by mass or less, and even more preferably 30 parts by mass or more and 70 parts by mass or less, relative to 100 parts by mass of the resin constituting the decorative layer.

The color layer and the design layer may contain additives such as an ultraviolet absorbing agent, a light stabilizer, and a coloring agent.
The thickness of the colored layer and the pattern layer may be appropriately selected depending on the desired pattern, but in order to conceal the background color of the adherend and improve the design, the thickness is preferably 0.5 μm or more and 20 μm or less, more preferably 1 μm or more and 10 μm or less, and even more preferably 2 μm or more and 5 μm or less.

Examples of the metal thin film include a thin film of a single metal element such as gold, silver, copper, tin, iron, nickel, chromium, cobalt, etc., a thin film of an alloy containing two or more of the above metal elements, etc. Examples of the alloy include brass, bronze, stainless steel, etc.
The thickness of the thin metal film can be about 0.1 μm or more and 1 μm or less.

The above-mentioned surface protection layer, primer layer, adhesive layer and decorative layer can be formed, for example, by applying a coating liquid containing a composition for forming each layer using a known method such as gravure printing, bar coating, roll coating, reverse roll coating or comma coating, and then drying and curing as necessary.

[Second release film]
The transfer sheet of the present invention may further have a second release film on the surface of the adhesive layer opposite to the release film. In particular, when the adhesive layer is a pressure-sensitive adhesive layer, the transfer sheet of the present invention has a second release film, which makes it easier to prevent blocking when the transfer sheet is wound into a roll during production, and makes it easier to prevent the transfer sheet from accidentally sticking to other objects.

When the peel strength between the release film and the transfer layer is defined as P1 and the peel strength between the second release film and the adhesive layer is defined as P2, it is preferable that P2<P1. By defining P2<P1, it is possible to easily peel off the second release film before the release film.
In this specification, the peel strength can be measured in accordance with the 180-degree peel test of JIS Z 0237:2009.

The second release film is not particularly limited as long as it can be peeled off from the adhesive layer, and a plastic film is preferably used.
The plastic film used as the second release film may be the same as the above-mentioned examples of the release film. Among the plastic films exemplified above, it is preferable to use a polyester resin in order to improve the handling of the transfer sheet, and among the polyester resins, it is particularly preferable to use polyethylene terephthalate.

It is preferable that the surface of the second release film that contacts the adhesive layer is treated with a release agent or the like. As the release agent, a known release agent such as a fluorine-based release agent or a silicone-based release agent can be used. By treating the second release film with a release agent or the like, it becomes easier to make the relationship between the peel strength P1 and the peel strength P2 P2 < P1.

The thickness of the second release film is not particularly limited, but in order to improve the handleability of the transfer sheet, it is preferably from 10 μm to 200 μm, more preferably from 15 μm to 150 μm, and even more preferably from 20 μm to 100 μm.

[Transfer sheet manufacturing method]
The method for producing a transfer sheet of the present invention includes at least a surface protective layer forming step, a primer layer forming step, and an adhesive layer forming step.

(Surface protective layer formation process)
The surface protective layer forming step is a step of forming a surface protective layer on a release film. The surface protective layer can be formed by applying a composition for forming the surface protective layer by a known method such as gravure printing, bar coating, roll coating, reverse roll coating, or comma coating, drying the composition as necessary, and curing the composition by irradiating the composition with ionizing radiation such as an electron beam.

(Primer layer formation process)
The primer layer forming step is a step of forming a primer layer on the surface protective layer formed in the surface protective layer forming step. The primer layer can be formed by applying a composition for forming the primer layer by a known method such as gravure printing, bar coating, roll coating, reverse roll coating, or comma coating, and drying and curing as necessary.

(Adhesive layer forming process)
The adhesive layer forming step is a step of forming an adhesive layer on the primer layer formed in the primer layer forming step. The adhesive layer can be formed by applying a composition for forming the adhesive layer by a known method such as gravure printing, bar coating, roll coating, reverse roll coating, or comma coating, and drying and curing as necessary.

(Decorative layer forming process)
The method for producing a transfer sheet of the present invention preferably further includes a decorative layer forming step, if necessary. The decorative layer forming step is a step of forming a decorative layer on the layer that forms the transfer layer of the transfer sheet.

The decorative layer forming step is preferably carried out between the primer layer forming step and the adhesive layer forming step, or between the surface protection layer and the primer layer forming step, and more preferably between the primer layer forming step and the adhesive layer forming step.
By carrying out the decorative layer forming step between the above steps, a decorative layer can be formed between the layers that constitute the transfer layer of the transfer sheet, making it easier to improve the weather resistance of the decorative layer.

The decorative layer can be formed by applying the composition that forms the decorative layer using a known method such as gravure printing, bar coating, roll coating, reverse roll coating, or comma coating, and then drying and curing as necessary.

[Member manufacturing method]
By using the transfer sheet of the present invention and transferring the transfer layer of the transfer sheet to an adherend, a member using the transfer sheet of the present invention can be produced.

The adherend is not particularly limited, and may be appropriately selected from among resins, paper, nonwoven or woven fabrics, wood, metals, nonmetallic inorganic materials, etc., depending on the application.
When a resin is used as the adherend, one or both sides of the sheet may be subjected to a physical or chemical surface treatment such as an oxidation method or a roughening method, if desired, in order to improve the adhesion between the transfer layer of the transfer sheet and the adherend. Metals used for the steel sheet include metal materials such as iron, aluminum, and copper, which may be subjected to a surface treatment such as hot-dip galvanizing or electrogalvanizing.
The shape of the adherend is not particularly limited, and may be a flat plate such as a sheet, or may have a three-dimensional shape such as a curved plate or a polygonal prism.

The method for producing a member of the present invention includes at least the following steps (1) and (2) in this order.
(1) A step of bringing the transfer layer side of the transfer sheet of the present invention into close contact with an adherend.
(2) A step of peeling off the release film of the transfer sheet from the tightly attached transfer sheet and adherend.

One example of the above step (1) is, for example, a method using a lamination method having the following steps (a1) and (a2) in order.
(a1) A step of contacting and superposing the transfer layer side of the transfer sheet on a flat adherend.
(a2) A step of applying heat and pressure from the release film side of the transfer sheet to bring the adherend on the flat plate and the transfer layer of the transfer sheet into close contact with each other.

Steps (a1) and (a2) can be carried out by a lamination method that combines heating and pressure using a roll transfer device or the like.

In step (a2), the lami roll temperature of the roll transfer device is preferably 180°C or less, more preferably 160°C or less. By setting the lami roll temperature to 180°C or less, it becomes easier to prevent the transfer layer of the transfer sheet from softening more than necessary, and the transfer layer can be transferred to the adherend in good condition. In addition, the lower limit of the lami roll temperature of the roll transfer device in step (a2) is not particularly limited as long as the transfer layer of the transfer sheet and the adherend are in close contact, but is usually 100°C or more, preferably 110°C or more, and more preferably 120°C or more.

As another example of the above (1), for example, there is an in-mold molding method which requires the following steps (z1) to (z4) in order.
(z1) A step of placing the transfer layer side of the transfer sheet described above facing the inside of an in-mold molding die.
(z2) A step of injecting a resin into the in-mold molding die.
(z3) A step of integrating the transfer sheet and the resin to bring the transfer layer of the transfer sheet and the resin into close contact with each other to form a resin molded body.
(z4) A step of removing the resin molded body from the in-mold molding die.

Furthermore, when the adhesive layer of the transfer sheet described above is a curable adhesive layer, it is preferable to have the following step (3) after the above step (2) in order to promote curing of the adhesive layer.
(3) Aging for a predetermined period of time at a constant temperature.

The temperature condition for aging is preferably 70° C. or less, and more preferably 65° C. or less. By setting the temperature at 70° C. or less, the curing reaction of the adhesive layer etc. proceeds slowly, and rapid shrinkage due to the curing reaction can be prevented. The lower limit of the temperature condition for aging varies depending on the configuration of the adhesive layer etc., but is usually 40° C. or more in order to promote the curing reaction of the thermosetting resin composition etc. contained in the adhesive layer.
The aging time varies depending on the configuration of the adhesive layer, etc., or the aging temperature conditions, but is usually 12 hours or more, preferably 24 hours or more, more preferably 48 hours or more, and even more preferably 72 hours or more.

In addition, when the above-mentioned transfer sheet has a second release film on the side opposite to the release film side of the adhesive layer, it is preferable to have the following step (0) before the above step (1).
(0) A step of peeling off the second release film from the transfer sheet to expose the adhesive layer.

[Materials]
A member using the transfer sheet of the present invention can be obtained by the above-mentioned method for producing a member.
A member using the transfer sheet of the present invention has at least an adhesive layer, a primer layer and a surface protective layer in this order on an adherend, the surface protective layer contains an ultraviolet absorber, the total content of the ultraviolet absorber per 100 parts by mass of the resin forming the surface protective layer is 10 parts by mass or less, and the surface protective layer satisfies the above-mentioned [1] or [2].
When a member is formed using the transfer sheet of the present invention, in the case where the transfer sheet has a decorative layer, the member can further have a decorative layer.

The member using the transfer sheet of the present invention has a UV absorber in the surface protective layer, and the total content of the UV absorber per 100 parts by mass of the resin forming the surface protective layer is 10 parts by mass or less, and the surface protective layer satisfies the above [1] or [2], so that it has long-term weather resistance.

The present invention will be specifically described below with reference to examples and comparative examples. Note that the present invention is not limited to the embodiments described in the examples.

1. Measurement and Evaluation 1-1. Evaluation of Weather Resistance of Appearance An accelerated weather resistance test using a metal halide lamp (MWOM) was carried out for 1500 hours on the members obtained in the Examples and Comparative Examples (a cycle of 20 hours of ultraviolet irradiation under the irradiation conditions below, followed by 4 hours of condensation under the condensation conditions below was repeated). After the accelerated weather resistance test, the appearance of the members was visually observed, and the appearance was evaluated according to the following criteria. The evaluation results are summarized in Table 1. The test equipment, irradiation conditions, and condensation conditions for the accelerated weather resistance test are as follows.
<Appearance evaluation criteria>
A: No change in appearance was observed.
B: A slight change in appearance, such as a slight change in color tone, was observed.
C: A significant change in appearance, such as a significant change in color tone, was observed.

<Test Equipment>
Manufactured by Daipla Wintes, product name "Daipla Metal Weather"
<Irradiation conditions>
Illuminance: 65 mW/cm ² , Black panel temperature: 63° C., Humidity inside chamber: 50% RH, Time: 20 hours <Condensation conditions>
Illuminance: 0 mW/cm ² , Humidity inside the tank: 98% RH, Time: 4 hours

1-2. Evaluation of Weather Resistance of Interlayer Adhesion The members obtained in the examples and comparative examples were subjected to an accelerated weathering test using a metal halide lamp (MWOM) for 500 hours under the same conditions as in 1-1 above. An adhesive tape (manufactured by Nichiban Co., Ltd., product name "Cellotape (registered trademark)") was attached to the surface of the surface protective layer side of the member after the accelerated weathering test, with an area of 2.5 cm x 2.5 cm, so that it protruded about 5 cm from the end of the member. Then, a peeling test was performed by pinching the protruding part of the attached adhesive tape and peeling the adhesive tape in a direction of 45° to the surface of the member. From the results of the peeling test, the interlayer adhesion was evaluated according to the following criteria. The evaluation results are summarized in Table 1.
<Evaluation criteria for interlayer adhesion>
A: No peeling was observed between the layers of the transfer sheet.
B: Slight peeling was observed in part of the interlayer of the transfer sheet.
C: Significant peeling was observed between the layers of the transfer sheet.

1-3. Evaluation of bleed-out resistance The members obtained in the examples and comparative examples were left in an environment of a temperature of 40° C. and a humidity of 90% RH for one week. The appearance of the members after leaving them was visually observed from the surface protective layer side, and the bleed-out resistance was evaluated according to the following criteria. The evaluation results are summarized in Table 1.
<Evaluation criteria for bleed-out resistance>
A: No change in appearance was observed.
B: Slight changes in appearance such as whitening, change in gloss, and precipitation of sheet components were observed.
C: Significant changes in appearance such as significant whitening, change in gloss, and precipitation of sheet components were observed.

2. Preparation of transfer sheet and member (Example 1)
An ionizing radiation curable resin composition 1 having the following formulation was applied to one side of a release film made of an untreated polyethylene terephthalate film (manufactured by Mitsubishi Chemical Corporation, product name "Diafoil E130") having a thickness of 26 μm, at a coating weight of ⁵ g/m2 to form an uncured resin layer. The uncured resin layer was then cured by irradiation with an electron beam (applied voltage: 175 keV, 5 Mrad (50 kGy)), to form a surface protective layer having a thickness of 5 μm.
<Ionizing radiation curable resin composition 1>
Trifunctional urethane acrylate oligomer: 100 parts by mass (manufactured by Arakawa Chemical Industries, Ltd., product name "Beamset 550B", weight average molecular weight: 5000)
Ultraviolet absorber 1: 5 parts by mass (manufactured by ADEKA CORPORATION, product name "ADEKA STAB LA-46", compound represented by the above general formula (I))
Ultraviolet absorber 2: 5 parts by mass (manufactured by BASF, product name "Tinuvin 479", a compound represented by the above general formula (II))

Next, a polycarbonate-based urethane acrylic copolymer (weight average molecular weight 50,000) was applied on the surface protective layer in an amount of 2.5 g/m ² after drying, and then dried to form a primer layer having a thickness of 2.5 μm.

Next, acrylic resin (PMMA, weight average molecular weight: 96,000) was applied on the primer in a coating amount of 5 g/ ^m2 after drying, and then dried to form a 5 μm thick adhesive layer having heat sealability. After forming the adhesive layer, it was aged at room temperature for 24 hours to obtain a transfer sheet of Example 1.

The adhesive layer of the transfer sheet of Example 1 obtained above was placed opposite one side of the adherend, a polycarbonate plate (thickness: 2 mm, manufactured by AGC, product name "Carbo Polish"), and laminated. Then, using a laminator (manufactured by ACO Brands Japan, product name "Desktop Roll Laminator B316A3"), the transfer sheet was heated and pressed at a lamination roll temperature of 160°C and a conveying speed of 0.5 m/min from the transfer sheet side, to bring the transfer layer of the transfer sheet into close contact with the adherend.
Next, the release film was peeled off from the tightly attached transfer sheet and adherend, to obtain the member of Example 1.

(Examples 2 to 7)
Transfer sheets and members of Examples 2 to 7 were obtained in the same manner as in Example 1, except that the type and amount of the ultraviolet absorbing agent in the surface protective layer were changed to those shown in Table 1.

(Comparative Examples 1 and 2)
Transfer sheets and members of Comparative Examples 1 and 2 were obtained in the same manner as in Example 1, except that the type and amount of the ultraviolet absorbing agent in the surface protective layer were changed to those shown in Table 1.

The ultraviolet absorbents 1 to 3 in Table 1 are as follows.
Ultraviolet absorber 1 (compound represented by the above general formula (I)):
Manufactured by ADEKA Corporation, product name "ADEKA STAB LA-46"
Ultraviolet absorber 2 (compound represented by the above general formula (II)):
BASF product name: Tinuvin 479
Ultraviolet absorber 3 (compound represented by the above general formula (III)):
BASF product "Tinuvin 1600"

In addition, the "content ratio of ultraviolet absorber 2 or ultraviolet absorber 3" in Table 1 means the ratio (mass%) of the content of ultraviolet absorber 2 or ultraviolet absorber 3 to the total content of ultraviolet absorber 1 and the content of ultraviolet absorber 2 or ultraviolet absorber 3 (100 mass%).

From the results in Table 1, it can be confirmed that Examples 1 to 7 having the characteristics of the present invention are excellent in weather resistance and further in bleed-out resistance, and therefore can exhibit excellent weather resistance even when used outdoors for a long period of time.
On the other hand, since the content of the total ultraviolet absorber in the surface protective layer was high in Comparative Example 1, and the content ratio of the hydroxyphenyltriazine compound represented by the general formula (II) in the surface protective layer was high in Comparative Example 2, both the weather resistance and the bleed-out resistance were poor.

The transfer sheet of the present invention has excellent weather resistance, and is therefore suitable for use as interior components for buildings such as walls, ceilings, and floors, exterior components for exterior walls, roofs, eaves ceilings, fences, and gates, fittings or fixtures such as various doors such as window frames and entrance doors, handrails, baseboards, moldings, window frames, door frames, and moldings, as well as general furniture such as chests of drawers, shelves, and desks, kitchen furniture such as dining tables and sinks, surface decorative panels for cabinets for low-electricity products and office automation equipment, and interior or exterior components for vehicles. Furthermore, components using the transfer sheet of the present invention are suitable for use in the various components mentioned above, especially components used in environments exposed to direct sunlight.

REFERENCE SIGNS LIST 1 Release film 2 Surface protective layer 3 Primer layer 4 Adhesive layer 5 Decorative layer 10 Transfer sheet 11 Transfer layer

Claims (8)

A transfer layer is provided on a release film.
The transfer layer has a surface protective layer, a primer layer, and an adhesive layer in this order from the release film side,
the surface protective layer contains an ultraviolet absorbing agent, and the total content of the ultraviolet absorbing agent relative to 100 parts by mass of a resin forming the surface protective layer is 10 parts by mass or less;
The transfer sheet further comprises a surface protective layer that satisfies the following [1].
[1] A composition comprising a hydroxyphenyltriazine compound represented by the following general formula (I) and a hydroxyphenyltriazine compound represented by the following general formula (II) as an ultraviolet absorbent,
The content of the hydroxyphenyltriazine compound represented by the following general formula (II) is 45 mass% or less relative to 100 mass% in total of the content of the hydroxyphenyltriazine compound represented by the following general formula (I) and the content of the hydroxyphenyltriazine compound represented by the following general formula (II).

A transfer layer is provided on a release film.
The transfer layer has a surface protective layer, a primer layer, and an adhesive layer in this order from the release film side,
the surface protective layer contains an ultraviolet absorbing agent, and the total content of the ultraviolet absorbing agent relative to 100 parts by mass of a resin forming the surface protective layer is 10 parts by mass or less;
The transfer sheet further comprises a surface protective layer that satisfies the following [2].
[2] The composition contains a hydroxyphenyltriazine compound represented by the following general formula (I) and a hydroxyphenyltriazine compound represented by the following general formula (III) as an ultraviolet absorbing agent.

3. The transfer sheet according to claim 2, wherein the content of the hydroxyphenyltriazine compound represented by the general formula (III) is 95% by mass or less relative to the total content of the hydroxyphenyltriazine compound represented by the general formula (I) and the content of the hydroxyphenyltriazine compound represented by the general formula ( III ) being 100% by mass. The transfer sheet according to any one of claims 1 to 3 , wherein the adhesive layer contains a colorant. The transfer sheet according to any one of claims 1 to 4 , further comprising a decorative layer between the adhesive layer and the primer layer. The transfer sheet according to any one of claims 1 to 5 , wherein the surface protective layer contains, as a resin component, a cured product of a curable resin composition. The transfer sheet according to any one of claims 1 to 6 , wherein the surface protective layer has a thickness of 1.5 µm or more and 30 µm or less. A method for manufacturing a member, comprising the following steps (1) and (2) in order:
(1) A step of bringing the surface of the transfer layer side of the transfer sheet according to any one of claims 1 to 7 into close contact with an adherend.
(2) A step of peeling off the release film of the transfer sheet from the tightly attached transfer sheet and adherend.