JP7484066B2 - Synthetic resin skin material, method of manufacturing a mold for forming a synthetic resin skin material, and method of manufacturing a synthetic resin skin material - Google Patents

Description

This disclosure relates to a synthetic resin skin material, a method for manufacturing a mold for forming a synthetic resin skin material, and a method for manufacturing a synthetic resin skin material.

In recent years, synthetic resin skin materials, which have excellent durability, have been widely used in place of natural leather and fibrous sheets for automobile interior parts (instrument panels, door trims, seats, ceilings, etc.), railway car interior parts, aircraft interior parts (trims, seats, ceilings, etc.), furniture, shoes, footwear, bags, interior and exterior components for building decoration, clothing coverings and linings, wall coverings, etc. Such synthetic resin skin materials have various uneven patterns on the outermost surface, and these uneven patterns characterize the appearance.
Generally, the concave-convex pattern in a synthetic resin skin material is formed on the skin layer. The general methods for forming the concave-convex pattern on the skin layer include a method for forming a resin layer for forming a skin layer on the surface of a release material on which a concave-convex pattern for transfer has been previously formed, and then transferring the concave-convex pattern of the release material to the skin layer, and a method for bringing the skin layer into contact with a mold such as an embossing roll having concave-convex patterns and applying heat and pressure to the mold to form the concave-convex pattern by embossing.
The method using a release agent is suitable for forming a fine uneven pattern, for example a leather-like uneven pattern, due to the thickness of the release agent, but is not suitable for forming a deeper uneven pattern.
In the method using a mold, the mold surface is usually either glossy or matte-finished, and although a glossy uneven pattern or an uneven pattern with a matte surface can be formed, the range of expression of the design surface is limited.

For this reason, a method for producing a synthetic resin skin material in which areas with different gloss are formed on the surface has been proposed.
For example, an embossing plate for producing an embossed sheet has been proposed, which is characterized by having fine irregularities formed on part of the substrate surface (see Patent Document 1), and a method for producing an embossed sheet has been described, which includes a step of partially forming a mask layer on the embossing plate substrate and performing a blasting treatment by spraying abrasive particles onto the substrate.
In addition, an embossed decorative material with variable gloss has been proposed, which is obtained by repeating the process of forming unevenness multiple times by forming a photosensitive resist on a metal cylinder, exposing and developing it to form a resist, etching it, and peeling off the resist (see Patent Document 2).

Japanese Patent Application Laid-Open No. 04-1025 Japanese Patent Application Laid-Open No. 11-254898

However, the method of partially forming a mask layer on the base material of an embossed plate described in Patent Document 1 and then performing a blast treatment requires the step of partially forming a mask layer, and the method of forming irregularities on the base material, then blasting the base material and polishing the convex parts to form smooth areas is a complicated process, and glossy smooth surfaces are formed only on the convex parts. Therefore, of the irregularities formed by the embossed sheet, only the bottom surfaces of the concave parts are smooth, and it cannot be said that the design freedom is sufficient.
Furthermore, as described in Patent Document 2, in order to obtain a desired design, a process of forming a resist in a pattern corresponding to the size of the unevenness, etching, and then peeling off the resist is carried out at least twice, and then, as a third process, a further etching process or blasting process is carried out. However, this method involves complicated processes, and the resulting embossed decorative material has fine unevenness all over its surface, which makes it difficult to fully discern differences in gloss with the naked eye.

An object of one embodiment of the present invention, which has been made in consideration of the above-mentioned conventional technology, is to provide a synthetic resin skin material which has an uneven surface on at least one surface with glossy and non-glossy areas, in which the difference in gloss level between the glossy and non-glossy areas is clear, and which has excellent design properties.
An object of another embodiment of the present invention is to provide a method for producing a mold for forming a synthetic resin skin material, which is useful for forming a synthetic resin skin material with excellent design, having an uneven surface with glossy and non-glossy areas on at least one surface and in which the difference in gloss level between the glossy and non-glossy areas is clear.
An object of another embodiment of the present invention is to provide a method for producing a synthetic resin skin material having an uneven surface with glossy and non-glossy areas on at least one surface, and in which the difference in glossiness between the glossy and non-glossy areas is clear, resulting in an excellent design.

Means for solving the above problems include the following aspects.
<1> A synthetic resin skin material having a synthetic resin layer having projections and recesses on at least one surface thereof, the surface of the synthetic resin layer having the projections and recesses having a glossy region and a non-glossy region, the difference in 60° specular gloss between the glossy region and the non-glossy region being 30 or more as measured in accordance with JIS Z 8741 (1997).

<2> The synthetic resin skin material according to <1>, wherein the highest points of the convex portions of the concave-convex portions of the synthetic resin layer are glossy regions, and the deepest points of the concave-convex portions are non-glossy regions.
<3> The synthetic resin skin material according to <1> or <2>, wherein the distance between the highest point of a convex portion and the deepest point of a concave portion in the concave-convex portion of the synthetic resin layer is in the range of 15 μm to 10 mm.
<4> The synthetic resin skin material according to any one of <1> to <3>, wherein the synthetic resin layer is a layer containing a colorant, or further includes a layer containing a thermoplastic resin and a colorant and different from the synthetic resin layer.

<5> A method for manufacturing a mold for forming a synthetic resin skin material, comprising: step A of copper plating the surface of a metal base material for use in mold production; step B of matting the copper-plated surface of the metal base material for use in mold production; step C of forming an etching resist on the matte-treated surface of the metal base material for use in mold production according to a design to be formed, and then etching to form recesses in areas where the etching resist is not formed; step D of peeling off the etching resist to obtain a mold precursor having a surface with projections and recesses and glossy and non-glossy areas; and step E of chrome plating the surface of the obtained mold precursor to obtain a mold.

<6> The method for producing a mold for forming a synthetic resin skin material described in <5> further includes, after step A and prior to step B, step F of forming projections and recesses as a base pattern on the surface of the metal base material for mold production using at least one means selected from laser engraving, mechanical engraving, electronic engraving, and etching.

<7> A method for producing a synthetic resin skin material, comprising step G of contacting a resin composition for forming a synthetic resin layer with a mold obtained by the method for producing a mold for forming a synthetic resin skin material described in <5> or <6>, and heating and pressurizing the mold to transfer the surface shape of the mold to the resin composition for forming a synthetic resin layer, thereby forming a synthetic resin layer having irregularities on one side.

According to one embodiment of the present invention, it is possible to provide a synthetic resin skin material having an uneven surface with glossy and non-glossy areas on at least one surface, with a clear difference in glossiness between the glossy and non-glossy areas, and excellent design properties.
According to another embodiment of the present invention, it is possible to provide a method for manufacturing a mold for forming a synthetic resin skin material, which is useful for forming a synthetic resin skin material with excellent design, having an uneven surface with glossy and non-glossy areas on at least one surface and a clear difference in glossiness between the glossy and non-glossy areas.
According to another embodiment of the present invention, it is possible to provide a method for producing a synthetic resin skin material having an uneven surface with glossy and non-glossy areas on at least one surface, and in which the difference in glossiness between the glossy and non-glossy areas is clear, resulting in an excellent design.

FIG. 1 is a schematic cross-sectional view showing one embodiment of a synthetic resin skin material according to the present disclosure. FIG. 1 is a schematic diagram showing an example of a process in a method for producing a mold for forming a synthetic resin skin material according to the present disclosure, which is applied to the manufacture of a mold for forming a synthetic resin skin material capable of forming a synthetic resin skin material having a glossy area on the top surface of the convex portion of the concave-convex portion. FIG. 1 is a schematic diagram showing an example of a process in a method for manufacturing a mold for forming a synthetic resin skin material according to the present disclosure, which is applied to the manufacture of a mold for forming a synthetic resin skin material capable of forming a synthetic resin skin material having a glossy region and a non-glossy region on the top surface of a convex portion. FIG. 2 is a schematic diagram showing an example of a step of forming a first-stage unevenness in a mold, among steps in a manufacturing method of a synthetic resin skin material having two stages of unevenness with different depths. FIG. 1 is a schematic diagram showing an example of a process for producing a synthetic resin skin material having two levels of unevenness with different depths, the process including forming a second level of unevenness in a mold and forming unevenness in the synthetic resin skin material using the mold thus obtained. 1 is an optical photograph showing the synthetic resin skin material of Example 1 in which one level of unevenness is formed and the top surfaces of the protrusions have glossy areas. 1 is an optical photograph showing a synthetic resin skin material of Example 2 in which two levels of unevenness are formed, and the top surface of the highest part of the protrusions has a glossy area.

Preferred embodiments of the present disclosure will now be described.
In the present disclosure, a numerical range described using "to" indicates a numerical range that includes the numerical values before and after "to" as the lower and upper limits.
In the present disclosure, when a plurality of substances corresponding to each component are present in the composition, the amount of each component in the composition means the total amount of the plurality of substances present in the composition, unless otherwise specified.
In the numerical ranges described in the present disclosure, the upper or lower limit value described in a certain numerical range may be replaced with the upper or lower limit value of another numerical range described in the present disclosure. In addition, in the numerical ranges described in the present disclosure, the upper or lower limit value described in a certain numerical range may be replaced with a value shown in the examples.
Also, in the present disclosure, combinations of two or more preferred aspects are more preferred aspects.
In the present disclosure, the term "process" includes not only an independent process but also a process that cannot be clearly distinguished from other processes as long as the intended purpose of the process is achieved.
In the various drawings, components designated by the same reference numerals are meant to be the same components.

<Synthetic resin skin material>
The synthetic resin skin material of the present disclosure has a synthetic resin layer having irregularities on at least one surface thereof, the surface of the synthetic resin layer having the irregularities has a glossy region and a non-glossy region, and the difference in 60° specular gloss between the glossy region and the non-glossy region, as measured in accordance with JIS Z 8741 (1997), is 30 or more.

The skin material of the present disclosure has irregularities on at least one surface, and the surface of the synthetic resin layer having the irregularities has a glossy region and a non-glossy region, and there is no particular restriction on the layer structure of the skin material, so long as the skin material has a synthetic resin layer (hereinafter sometimes referred to as a specific resin layer) in which the difference in 60° specular gloss measured under the following conditions between the glossy region and the non-glossy region is 30 or more. That is, the skin material may have a single-layer structure consisting of only the specific resin layer, or may have a multilayer structure having any layer on the surface opposite the side of the specific resin layer having the irregularities.
In the case of a skin material having a one-layer structure, the specific resin layer may contain a colorant.
The multi-layered skin material may contain any layer in addition to the specific resin layer. For example, the multi-layered skin material may further include a layer that contains a thermoplastic resin and a colorant in addition to the specific resin layer, and is different from the specific resin layer. In the latter case, the specific resin layer may be a transparent layer.

One embodiment of the synthetic resin skin material of the present disclosure will be described with reference to Fig. 1. The synthetic resin skin material shown in Fig. 1 is an example of a skin material having a multi-layer structure, and the multi-layer structure skin material is not limited to the example shown in Fig. 1 described in detail below.
FIG. 1 is a schematic cross-sectional view showing one embodiment of the layer structure of a synthetic resin skin material (hereinafter, sometimes simply referred to as a "skin material") 10 according to the present disclosure.
In the embodiment shown in Fig. 1, the skin material 10 has a base material layer 12, an adhesive layer 14, and a skin layer 16 in this order. The synthetic resin layer having irregularities in this disclosure corresponds to the skin layer 16 shown in Fig. 1. In Fig. 1, the base material layer 12 is provided on the surface opposite to the surface having irregularities of the skin layer 16 as a synthetic resin layer, but the base material layer 12 is an optional layer, and the adhesive layer 14 is also an optional layer provided for the purpose of improving adhesion between the base material layer 12 and the skin layer 16.

The skin layer of the synthetic resin skin material in the embodiment shown in FIG. 1 (hereinafter also simply referred to as "skin layer") has irregularities on the surface opposite to the base layer, and part of the irregular surface has glossy regions a (represented by straight lines in the cross-sectional view) and non-glossy regions b (represented by wavy lines in the cross-sectional view), and corresponds to the specific resin layer in the present disclosure.
The unevenness, glossy regions and non-glossy regions of the skin layer are formed by contacting the resin composition for forming the skin layer with a mold for forming a synthetic resin skin material, and transferring the surface shape of the mold to the resin composition for forming the skin layer by heating and pressurizing, as described below.
Hereinafter, the process of transferring the surface shape of a mold to a resin composition for forming a synthetic resin layer (in the embodiment shown in FIG. 1, a resin composition for forming a skin layer) by heating and pressurizing to form a synthetic resin layer having irregularities and the like is referred to as embossing.

The skin material in the embodiment shown in Fig. 1 has a skin layer with excellent designability formed by embossing using a mold with a complex surface shape, and has a large difference in glossiness between the glossy and non-glossy regions of the skin layer. Specifically, the difference in Gs(60°) between the glossiness of the glossy region and the glossiness of the non-glossy region of the skin layer surface measured in accordance with JIS Z 8741 (1997) is 30 or more.
The difference in gloss level is preferably 35 or more, and more preferably 40 or more.

By having a difference in 60° specular gloss between the glossy and non-glossy areas of 30 or more, the skin material of the present disclosure can achieve a complex design on the surface with a large difference in gloss between the glossy and non-glossy areas, and further has the advantage that the appearance of the complex design on the surface is easily maintained even when the skin material of the present disclosure is applied to the surface of a resin molded body or the like and subjected to heat molding processing.

The skin material of the present disclosure may have any structure as long as it is provided with the specific resin layer defined above, and may have a single-layer structure consisting of only the specific resin layer, or may have other layers that are typically provided in skin materials, with the specific resin layer as the skin layer, as long as the effect is not impaired.
The other layers include a base layer, which will be described in detail below. The other layers will be described later.

Hereinafter, one embodiment of the skin material of the present disclosure will be described in order along with the materials that constitute it.
First, the multi-layered skin material will be described.
(A. Multi-layered skin material)
An example of a skin material having a multi-layer structure is a skin material having a layer structure as shown in FIG.

[A-1. Base material layer]
The multi-layered skin material of the present disclosure may have a base layer. As described above, the base layer is any layer containing a synthetic resin, and the synthetic resin is a thermoplastic resin. There is no particular limitation on the thermoplastic resin that can be used for the base layer. Depending on the application to which the skin material is applied, for example, affinity with the resin constituting the molded article to which the skin material is applied, Taking into consideration various conditions such as extensibility when molded, the resin can be appropriately selected from known thermoplastic resins.
Examples of thermoplastic resins that can be used for the base layer include polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC resin), polystyrene (PS), polyvinyl acetate (PVAc), polyurethane (PUR), Acrylonitrile/butadiene/styrene copolymer (ABS resin), acrylonitrile/styrene copolymer (AS resin), acrylic resin such as polycarbonate (PC) and polymethyl methacrylate (PMMA), fluorine resin such as polytetrafluoroethylene (PTFE) Resins and the like can be mentioned.
Among these, from the viewpoints of flexibility, thermoformability, etc., the thermoplastic resin contained in the base layer is preferably a PVC resin, an ABS resin, an AS resin, PC, PP, or a mixture of PC and ABS resin (PC/ ABS) or the like, more preferably PVC resin, ABS resin, or the like, and further preferably PVC resin.
PVC resin is a resin obtained by addition polymerization of vinyl chloride monomer (CH ₂ =CHCl). The degree of polymerization in PVC resin is appropriately selected within the range of about 400 to 3000 depending on the purpose.

The base layer may contain only one type of resin, or two or more types of resins.
In addition, when the base layer contains a PVC resin, it may contain a resin other than the PVC resin. Examples of other resins that can be used in combination with the PVC resin include the above-mentioned thermoplastic resins other than the PVC resin.
When the substrate layer contains a PVC resin and another resin, the content of the PVC resin relative to the total amount of resins contained in the substrate layer is preferably 60 mass % or more.

The base layer may further contain other components in addition to the thermoplastic resin.
Other ingredients include colorants, plasticizers, fillers, lubricants, processing aids, and the like.

(Coloring Agent)
The substrate layer may contain a colorant. When the substrate layer contains a colorant, the skin material can be given a design. When the skin material is applied to the surface of a molded body, the skin material is placed on the surface of the resin that is the substrate of the molded body to produce the molded body. At that time, the skin material containing the colorant can suppress the substrate from affecting the appearance of the molded body, and can give the molded body any hue.

When the base layer contains a colorant, the colorant is not particularly limited, and dyes, pigments, etc. can be appropriately selected and used.
Examples of colorants include inorganic pigments such as titanium white (titanium dioxide), zinc white, ultramarine, cobalt blue, red iron oxide, vermilion, yellow lead, titanium yellow, and carbon black, organic pigments or dyes such as quinacridone, permanent red 4R, isoindolinone, Hansa Yellow A, phthalocyanine blue, indanthrene blue RS, and aniline black, metal pigments selected from the group consisting of foil powders of metals such as aluminum and brass, and pearlescent (pearl) pigments selected from the group consisting of foil powders of titanium dioxide-coated mica and basic lead carbonate. Among these, pigments that are colorants with excellent weather resistance and durability are preferred, and black pigments such as carbon black, aniline black, and perylene black are more preferred from the viewpoint of effectively hiding the molding substrate.
If necessary, the base layer may contain an extender pigment (filler) such as calcium carbonate, silica (silicon dioxide), alumina (aluminum oxide), barium sulfate, or the like.
The base layer may contain only one type of colorant, or may contain two or more types of colorant for the purpose of adjusting the hue, etc.

There is no particular restriction on the content of the colorant in the resin composition used to form the base layer, and the type and content of the colorant to be used may be appropriately selected depending on the desired hue of the skin material, the hiding power of the molded base material, and the like.
When a colorant is used, the content of the colorant is generally preferably 1% by mass to 20% by mass, and more preferably 2% by mass to 10% by mass, based on the total solid content of the resin composition constituting the base layer. Here, the solid content refers to the total amount of the components excluding the solvent among all the components of the resin composition constituting the base layer.

(Plasticizer)
The base layer may contain a plasticizer for the purpose of improving flexibility. When the base layer contains a PVC resin, it is preferable that the base layer contains a plasticizer.
The plasticizer may be any known plasticizer without limitation. Examples of the plasticizer include phthalate ester plasticizers such as diisodecyl phthalate, di-2-ethylhexyl phthalate, and diisononyl phthalate, fatty acid ester plasticizers such as dioctyl adipate and dioctyl sebacate, trimellitic acid ester plasticizers such as trioctyl trimellitate, triaryl phosphate ester plasticizers such as tricresyl phosphate and trixylyl phosphate, epoxy plasticizers such as epoxidized soybean oil, and polyester plasticizers such as polypropylene adipate.
The base layer may contain only one type of plasticizer, or may contain two or more types of plasticizer.

The thickness of the substrate layer is preferably in the range of 50 μm to 500 μm, more preferably in the range of 100 μm to 350 μm. When the thickness is in the above range, breakage due to melting of the synthetic resin skin material is effectively suppressed when a molded article is formed by thermal processing using the skin material, and further, the hiding property of the molding substrate used in the molded article is improved.
The thickness of the base layer and the thickness of any of the layers in the synthetic resin skin material described below can be measured by observing a cut surface of the synthetic resin skin material cut perpendicular to the surface direction. Therefore, the thickness of each layer in the skin material described in this disclosure refers to the thickness after drying, unless otherwise specified.

The method for forming the substrate layer is not particularly limited, and known sheet forming methods, such as an extrusion method in which the substrate is extruded using a T-die or the like, a calendar method, a casting method, or the like, can be used.
Among them, the calendar method is preferred because of the ease of production and the ease of maintenance of the equipment. In particular, when the base layer contains a colorant, the calendar method allows a softened resin and a solid colorant to be supplied to a calendar roll and molded into a sheet or film, so that base layers containing various colorants can be easily produced.
Furthermore, by using the calendar method, cleaning of the inside of the device, which is required when changing the type or amount of colorant, can be performed more easily than with molding methods such as extrusion, etc. Therefore, when a colorant is contained in the base material layer, by using the calendar method, various base material layers having desired hues can be easily produced, and the method is also suitable for small-lot production of synthetic resin skin materials.

[A-2. Surface layer as specific resin layer]
In the embodiment shown in Fig. 1, the skin layer functions as the specific resin layer in the present disclosure. The skin layer as the specific resin layer (hereinafter, may be simply referred to as the skin layer) contains a synthetic resin, and the synthetic resin preferably contains a thermoplastic resin.
The thermoplastic resin contained in the surface layer is preferably at least one selected from the group consisting of PVC resin, fluororesin, and acrylic resin, from the viewpoints of excellent transparency and retention of the uneven pattern formed on the surface layer.

The surface layer may contain only one type of resin, or two or more types of resins.
In addition, when the skin layer contains a PVC resin, the skin layer may further contain a resin other than the PVC resin. Examples of other resins that can be used in combination with the PVC resin include the above-mentioned thermoplastic resins other than the PVC resin.
When the skin layer contains a PVC resin and another resin, the content of the PVC resin relative to the total amount of resins contained in the skin layer is preferably 60 mass % or more.

The skin layer may further contain other components in addition to the thermoplastic resin.
Other components include plasticizers, fillers, lubricants, processing aids, and the like.
The optional components in the skin layer and the method for forming the smooth synthetic resin layer for forming the skin layer are the same as those for the base layer in the multi-layered skin material, except that no irregularities are formed on at least one surface, and the preferred examples are also the same.

The surface layer as the specific resin layer of the present disclosure has a complex uneven pattern with a large difference in glossiness between the glossy and non-glossy parts. This complex uneven pattern is preferably formed by a mold obtained by the manufacturing method of the present disclosure described below.
The depth of the unevenness pattern that characterizes the above of the skin material, i.e., the distance between the highest point of the convexity in the unevenness of the skin layer and the deepest point of the concaveity, is determined according to the intended design. From the viewpoint of making the difference in glossiness between the glossy area and the non-glossy area formed in the unevenness of the skin layer more clear, the distance between the highest point of the convexity in the unevenness of the skin layer and the deepest point of the concaveity is preferably in the range of 15 μm to 10 mm, more preferably in the range of 20 μm to 1 mm, and even more preferably in the range of 20 μm to 100 μm.
The design of the uneven pattern can be any design, such as a checkered pattern in which rectangles of the same size are regularly arranged in a plan view, a lattice pattern, an uneven pattern having circular protrusions in a plan view, an irregular pattern such as a wave pattern, or a line pattern.
Furthermore, the positions of the glossy and non-glossy areas in the uneven pattern can be appropriately selected, allowing various designs to be realized according to purpose.

The thickness of the skin layer is preferably in the range of 5 μm to 100 μm from the viewpoints of the retention of the uneven pattern and the degree of freedom in design.
Here, the thickness of the skin layer refers to the distance from the highest point of the convex portion of the unevenness of the skin layer on which the uneven pattern is formed to the bottom surface of the skin layer, i.e., the interface between the skin layer and the base layer or any layer provided adjacent to the skin layer.
When the skin layer has a laminated structure of two or more layers as described above, the thickness of the skin layer refers to the total thickness of the multiple layers.

There is no particular limitation on the method for forming the uneven pattern on the surface of the skin layer opposite to the surface on the base layer side, but from the viewpoint of easily imparting a distinctive design to the skin layer, it is preferable to use a method in which a mold obtained by the manufacturing method for a mold for forming a synthetic resin skin material of the present disclosure described below is used, and the surface shape of the mold is transferred by embossing to form the skin layer.
That is, a preferred method is to first form a resin layer for forming a skin layer having a smooth surface, and then emboss the resin layer for forming a skin layer using a mold obtained by the manufacturing method described below to form a desired design. The manufacturing method of the mold for forming a synthetic resin skin material of the present disclosure will be described later.

The surface layer as the specific resin layer is obtained by first forming a surface layer forming resin layer, which is a synthetic resin layer with a smooth surface, and then forming unevenness. There is no particular limitation on the method of forming the surface layer forming resin layer, and the surface layer forming resin layer can be formed by preparing a surface layer forming composition containing each of the above-mentioned components and forming it into a sheet by a calendar method, a casting method, an extrusion method, or the like. In addition, the surface layer forming composition can be applied directly or via an adhesive layer or the like described below onto the substrate layer to form a surface layer forming resin layer, which can then be cured to form the surface layer on the substrate layer.
Among these, the method of forming the resin layer for forming the surface layer by the calendar method is preferred, since the surface layer has better uniformity and the inside of the apparatus can be easily cleaned after the surface layer containing the colorant is formed.

The multilayered skin material of the present disclosure may be, for example, a multilayered structure including a skin layer as a specific resin layer and a base layer. When the skin layer is a specific resin layer, it is preferable that the surface opposite to the surface on which the uneven pattern is formed of the skin layer has the above-mentioned base layer.

The skin material of the present disclosure may have other known layers in addition to the skin layer as the specific resin layer and the base layer which is a preferred optional layer.
Other known layers include an adhesive layer, a design layer, and the like.
For example, the adhesive layer in the skin material improves the adhesion between layers in the multi-layered skin material, for example, the adhesion between the skin layer and the base layer described above. Also, the design layer in the skin material can provide various designs in addition to a complex uneven pattern with a large difference in gloss between the glossy and non-glossy areas, depending on the intended use of the skin material.
Optional layers other than the substrate layer that may be included in the skin material of the present disclosure will now be described.

[A-3. Adhesive layer]
The skin material of the present disclosure may have an adhesive layer. The adhesive layer improves adhesion between adjacent layers in a multi-layered skin material, such as a base layer and a skin layer. It may be provided to further improve the
When the skin material has a multi-layer structure, the adhesive layer can be formed between adjacent layers. More specifically, for example, when the skin material has a base layer and a skin layer, the adhesive layer can be formed between adjacent layers. The layer can be formed by laminating an adhesive on the surface of the base layer and drying it. The lamination (formation) of the adhesive layer may be performed by a transfer method or a coating method.
The adhesive used to form the adhesive layer that is provided as desired is not particularly limited and can be appropriately selected depending on the purpose. For example, (1) a urethane-based emulsion adhesive, (2) a vinyl chloride-based adhesive, (3) two-component curing polyester adhesives, and (4) two-component curing urethane adhesives are preferably used.
Typically, when forming a skin material by laminating a base layer and a skin layer, an adhesive layer is formed by applying an adhesive to the surface of the base layer.
When the skin material has an adhesive layer, the skin material may have only one adhesive layer, or may have two or more adhesive layers as required.
As described above, the adhesive can be applied by any of the known methods such as the transfer method and the coating method. From the viewpoint of easily forming an adhesive layer of uniform thickness, the transfer method is preferred. It is preferable to use the method.
In addition, when the adhesive layer is formed by a transfer method, a protective sheet may be provided on the surface of the adhesive layer in order to protect the surface of the adhesive layer that has been previously prepared. , release-treated paper, resin-laminated paper, etc. can be used appropriately.

[A-4. Design layer]
The skin material of the present disclosure may have a design layer.
The design layer may be a printed layer formed by a printing method, or may be a colored layer containing a colorant.
The design layer may be, for example, a printed layer formed by a printing method on the surface of the skin layer opposite to the surface having the uneven pattern or on the surface of the base layer. Examples of the printed layer include layers formed by a known printing method using a printing ink containing a resin. As the printing ink containing a resin, a printing ink containing an acrylic resin, a vinyl chloride-vinyl acetate copolymer, or the like is preferred from the viewpoint of being able to form a clear printed image.
There are no particular limitations on the printing method applied to form the printed layer, and any printing method can be applied, such as gravure printing (intaglio printing), letterpress printing, offset printing, inkjet printing, and screen printing.
The design layer is preferably a printing ink layer containing at least one material selected from acrylic resins and vinyl chloride-vinyl acetate copolymers.

The design layer may be a colored layer. Examples of the colored layer include a layer formed of a resin composition containing any colorant. For example, a design layer formed by forming a resin composition containing an acrylic resin and a colorant selected from those listed as colorants that can be used in the base layer into a film by a calendar method, an extrusion method, a casting method, or the like.
Any known coloring agent can be used as the coloring agent. In addition, by using a metal pigment, a pearl pigment, or the like as the coloring agent, a distinctive design can be imparted to the surface layer.
When the design layer is a colored layer, the colored layer may contain only one type of colorant, or may contain two or more types of colorants in combination.

Specific examples of acrylic resins that can be used to form the design layer include polymers or copolymers of methacrylic acid or methacrylic acid esters, such as polymethyl methacrylate (PMMA), and copolymers of alkyl methacrylate, alkyl acrylate, and styrene. From the standpoint of formability, mixtures of copolymers of alkyl methacrylate, alkyl acrylate, and styrene, and copolymers of methyl methacrylate and methyl acrylate are preferred.

Next, the single-layered skin material will be described.
(B. Single-layered skin material)
When the skin layer of the present disclosure has a single-layer structure, the single-layer structure skin material may be a skin material consisting of only a specific resin layer having the above-defined irregularities on at least one surface.

(B-1. Specific Resin Layer)
The specific resin layer in the single-layered skin material of the present disclosure has, on at least one surface, a complex uneven pattern with a large difference in glossiness between the glossy and non-glossy areas as defined above.
The depth of the unevenness pattern that characterizes the design of a single-layer skin material, i.e., the distance between the highest point of the convex portion and the deepest point of the concave portion in the unevenness of the skin layer, is determined according to the desired design.
From the viewpoint of making the difference in glossiness between the glossy and non-glossy regions formed in the unevenness of the specific resin layer more apparent, the distance between the highest point of the convex portion and the deepest point of the concave portion in the unevenness of the specific resin layer is preferably in the range of 15 μm to 10 mm, more preferably in the range of 20 μm to 1 mm, and even more preferably in the range of 20 μm to 100 μm.
The design of the uneven pattern is arbitrary and can be selected from any design depending on the purpose, such as a checkered pattern in which rectangles of the same size are regularly arranged in a plan view, a lattice pattern, an uneven pattern having circular protrusions in a plan view, an irregular pattern such as a wavy pattern, or a line pattern.
Furthermore, the positions of the glossy and non-glossy areas in the uneven pattern can be appropriately selected, allowing various designs to be realized according to purpose.

Here, the thickness of the specific resin layer refers to the distance from the highest point of the convex portion of the concave-convex pattern formed on the specific resin layer to the bottom surface of the specific resin layer.

There is no particular limitation on the method for forming the uneven pattern on at least one surface of the specific resin layer, but from the viewpoint of easily imparting a distinctive design to the specific resin layer, it is preferable to use a method in which a mold obtained by the manufacturing method for a mold for forming a synthetic resin skin material according to the present disclosure described below is used, and the specific resin layer is formed by transferring the surface shape of the mold by embossing.
That is, a method is preferred in which a resin layer for forming a specific resin layer having a smooth surface is first formed, and then the resin layer for forming the specific resin layer is embossed using a mold obtained by the manufacturing method described below to form a desired design. The manufacturing method of the mold for forming a synthetic resin skin material of the present disclosure will be described later.

When the skin material of the present disclosure has a single-layer structure consisting of only a specific resin layer, there are no particular limitations on the thermoplastic resin that can be used in the specific resin layer.
Examples of thermoplastic resins that can be used for the specific resin layer in the skin material having a single-layer structure include the resins exemplified for the base layer already described, for example, acrylic resins such as PE, PP, PVC resin, PS, PVAc, PUR, ABS resin, AS resin, PC, and PMMA, and fluororesins such as PTFE.
In particular, from the viewpoints of flexibility, heat moldability, and the like, the thermoplastic resin contained in the specific resin layer preferably includes PVC resin, ABS resin, AS resin, PC, PP, a mixture of PC and ABS resin (PC/ABS), and the like, more preferably includes PVC resin, ABS resin, and the like, and even more preferably includes PVC resin.

The specific resin layer may further contain other components in addition to the thermoplastic resin.
Other ingredients include colorants, plasticizers, fillers, lubricants, processing aids, and the like.
The optional components in the specific resin layer and the method for forming the smooth synthetic resin layer for forming the specific resin layer are the same as those for the base layer in the multilayered skin material, except that no irregularities are formed on at least one surface, and the preferred examples are also the same.

The thickness of the specific resin layer is preferably in the range of 50 μm to 500 μm, and more preferably in the range of 100 μm to 350 μm. By having the thickness of the specific resin layer in the above range, breakage due to melting of the skin material when a molded body is formed by thermal processing using the skin material is effectively suppressed, and further, the hiding property of the molding substrate used in the molded body is improved.

When the skin material of the present disclosure has a single-layer structure consisting of only a specific resin layer, by incorporating a colorant or the like into the specific resin layer, it is possible to impart any hue, as well as a rough pattern with a large difference in glossiness between the glossy and non-glossy areas on the surface, just like a skin material with a multi-layer structure, and to impart various complex designs to the molded product, etc.

[Method of manufacturing a mold for forming a synthetic resin skin material]
A mold that can be used to manufacture the skin material of the present disclosure is preferably manufactured by the manufacturing method for a mold for forming a synthetic resin skin material of the present disclosure (hereinafter, sometimes referred to as manufacturing method (I) of the present disclosure).
The manufacturing method (I) of the present disclosure includes a step A of copper plating a surface of a metal substrate for use in producing a mold (hereinafter sometimes simply referred to as a "metal substrate"), a step B of applying a matte treatment to the copper-plated surface of the metal substrate for use in producing a mold, a step C of forming an etching resist on the matte-treated surface of the metal substrate for use in producing a mold in accordance with a design to be formed, and then etching to form recesses in areas where the etching resist is not formed, a step D of peeling off the etching resist to obtain a mold precursor having a surface having projections and recesses and glossy areas and non-glossy areas, and a step E of chrome plating the surface of the obtained mold precursor to obtain a mold.

Furthermore, if desired, after step A and prior to step B, a step F may be further included in which projections and recesses are formed as a base pattern on the surface of the metal substrate for die production by using at least one means selected from laser engraving, mechanical engraving, electronic engraving, and etching.
It should be noted that step F can be performed multiple times. Steps C and D can be performed multiple times in this order. By performing these steps multiple times, the difference in glossiness between the glossy and non-glossy parts can be made large, and the depth or height of the unevenness can be made multiple stages, so that a mold capable of imparting a more complex design to the skin layer can be produced.

The production method (I) of the present disclosure will be described with reference to the drawings.
FIG. 2 is a schematic diagram showing an example of a process in the manufacturing method (I) of the present disclosure that is applied to the manufacture of a mold for forming a synthetic resin skin material having a glossy region on the top surface of a protrusion of the synthetic resin skin material.

Fig. 2(a) is a schematic cross-sectional view showing an embodiment in which a metal substrate 20 for mold fabrication is plated with copper (not shown) (step A). In Fig. 2, the metal substrate 20 is shown as a flat substrate, but the same manufacturing method can be applied to a cylindrical substrate.
As the metal substrate, it is preferable to use a substrate containing a metal such as iron or aluminum from the viewpoints of workability and strength.
The thickness of the copper plating layer is preferably in the range of 20 μm to 12 mm, and more preferably in the range of 25 μm to 1.1 mm.
Copper plating can be carried out by a conventional method.
Prior to the copper plating, the metal substrate may be nickel plated if desired.

2(b) is a schematic cross-sectional view showing a state in which a matte treatment is applied to the copper-plated surface of the metal base material 20. The matte treatment roughens the surface of the metal base material 20 (step B).
An example of the matte treatment is a blasting treatment in which hard abrasive particles are sprayed onto the surface.
An example of the blasting treatment is sandblasting treatment. Sandblasting treatment is a method in which hard abrasive particles of various particle sizes and hardness are sprayed onto the surface of a metal substrate from an air nozzle, and examples of the abrasive particle material include glass beads, alumina particles, steel particles, and silica sand. The average particle size of the abrasive particles can be selected depending on the purpose, but is generally preferably 30 μm to 90 μm.
Examples of grinding particles suitable for the manufacturing method (I) of the present disclosure include No. 280 sand (spherical particles with a particle size of 30 μm to 50 μm), No. 180 sand (spherical particles with a particle size of 50 μm to 90 μm), and the like.

In step B, by controlling the conditions of the blasting process, the degree of roughening can be adjusted, and a non-glossy surface with the desired gloss difference can be formed relative to the smooth surface of the skin layer, i.e., the glossy area. Generally, the gloss (Gs(60°)) of the smooth surface of a synthetic resin skin material, i.e., the glossy area, is about 40 to 60, and the blasting process should be performed under conditions that result in a gloss difference of 30 or more.

Next, an etching resist 22 is formed on the surface of the metal base material, the surface of which has been roughened by the blasting treatment, in an area where it is desired to maintain the rough surface, and an etching treatment is performed. The etching treatment engraves the areas where the etching resist 22 is not formed, forming recesses in the metal base material as shown in Fig. 2(c), and the side and bottom surfaces of the recesses are smoothed by the etching treatment to form glossy areas (Step C).
Thereafter, as shown in FIG. 2(d), the etching resist is peeled off to leave a mold 24 having a smooth surface that provides a glossy region in the skin layer and a rough surface that provides a non-glossy region (step D).
The metal base material having the irregularities shown in FIG. 2(d) is subjected to a chrome plating process (not shown) to obtain a mold having irregularities, roughened regions and non-roughened regions on its surface (Step E).

FIG. 3 is a schematic diagram showing an example of another step in the manufacturing method (I) of the present disclosure, which is applied to the manufacture of a mold for forming a synthetic resin skin material having a glossy area and a non-glossy area on the top surface of a protruding portion of the synthetic resin skin material.
FIG. 3A is a schematic cross-sectional view showing an embodiment in which a metal base material 20 for making a die is plated with copper (not shown) (Step A).
FIG. 3(b) is a schematic cross-sectional view showing a state in which an etching resist is partially formed on the copper-plated surface of a metal base 20, and then etching is performed to form recesses in desired regions of the metal base (step F).
The method for forming recesses on the copper-plated metal substrate surface may be any method, such as electroforming mill embossing, laser engraving, mechanical engraving, electronic engraving, etching, etc., and it is preferable to use at least one method selected from laser engraving, mechanical engraving, electronic engraving, and etching.

Figure 3(c) is a schematic cross-sectional view showing the state where the metal substrate with the recesses shown in Figure 3(b) has been subjected to a blasting treatment. The surface of the metal substrate 20 is roughened by the blasting treatment (step B). As shown in Figure 3(c), a method can be used in which, prior to step B, recesses are first formed in the metal substrate, and then the blasting treatment of step B is performed. This order of steps results in a mold capable of forming a non-glossy area on the bottom surface of the recesses in the metal substrate, i.e., on the top surface of the protrusions of the skin material.

In Fig. 3(d), an etching resist 22 is formed on the metal substrate having a recess and a roughened surface, and then an etching process is performed. The etching process forms recesses in the areas of the metal substrate where the etching resist 22 is not formed, and the metal surface is smoothed (step C). The smoothed parts of the mold recesses become areas where glossy areas of the skin layer protrusions can be formed.
FIG. 3E is a schematic cross-sectional view showing the state of the metal substrate after the etching resist 22 has been peeled off (step D).

In the manufacturing method (I) of the present disclosure, by combining etching processes such as the etching process involving engraving that forms recesses as shown in FIG. 2(c) and the multi-stage etching processes shown in FIGS. 4(e) to 5(a) described below, a smooth surface can be formed at any location, such as the recesses of a mold, and the resulting smooth surface can form glossy areas at any location of the uneven pattern in the skin layer, which can be said to be a major advantage of the manufacturing method (I) of the present disclosure and the manufacturing method of synthetic resin skin material described below.

The metal base material having the irregularities shown in FIG. 3( e ) is subjected to a chrome plating process (not shown) to obtain a mold having irregularities, roughened regions and non-roughened regions on its surface (step E).
As shown in FIG. 3(e), the obtained mold is a mold that gives a shape having glossy and non-glossy areas to the top surfaces of the protruding portions of the skin layer.

In this way, by combining blasting and etching, it is easy to obtain a mold that can impart irregularities, glossy areas, and non-glossy areas to any area of the surface layer.

[Method of manufacturing synthetic resin skin material]
Although there are no particular limitations on the method for producing the skin material of the present disclosure, a method for producing the skin material using a mold produced by production method (I) of the present disclosure is preferred. That is, it is preferred to produce a synthetic resin skin material using a mold capable of imparting a complex design to the skin material, which mold is produced by the method for producing a mold for forming a synthetic resin skin material of the present disclosure that can be used for producing the skin material.
Hereinafter, the method for producing a synthetic resin skin material according to the present disclosure may be referred to as the production method (II) according to the present disclosure.
The manufacturing method (II) of the present disclosure includes a step G of contacting a synthetic resin layer with the mold obtained by the above-described manufacturing method for a mold for forming a synthetic resin skin material (manufacturing method (I) of the present disclosure), and heating and pressurizing the mold to transfer the surface shape of the mold to the synthetic resin layer, thereby forming a specific resin layer.

4 and 5 are schematic diagrams showing steps in a method of producing a skin material (production method (II) of the present disclosure) by producing a mold for forming a synthetic resin skin material having two levels of unevenness with different depths for the skin material of the present disclosure (production method (I) of the present disclosure) and using the mold for forming a synthetic resin skin material obtained by production method (I) of the present disclosure.
FIG. 4 shows an example of a step of forming a first-stage unevenness in a mold in the manufacturing method (I) of the present disclosure, and FIG. 5 is a schematic diagram showing an example of a step of forming a second-stage unevenness in a mold in the manufacturing method (I) of the present disclosure, and a step of forming unevenness in a synthetic resin layer using the obtained mold to obtain a skin material in the manufacturing method (II) of the present disclosure.

4(a) to 4(d) show steps similar to those shown in FIGS. 3(a) to 3(d) described above.
Then, a further etching process is performed to further carve out the area where the etching resist 22 is not formed. In this way, as shown in Fig. 5(a), a metal base material having two levels of unevenness, with a smooth area and a rough area in the recessed area, is obtained (step D).
Furthermore, as shown in FIG. 5(b), the surface of the metal base material is chrome plated to form a chrome plating layer 30, thereby obtaining a mold 32 (step E).
As shown in FIG. 5( c ), the obtained mold 32 is brought into close contact with a synthetic resin layer, and an embossing process is performed by applying heat and pressure, thereby forming a single-layer synthetic resin skin material 34 onto which the unevenness of the mold 32 is transferred.
As shown in FIG. 5( c ), the formed synthetic resin skin material 34 having a single layer structure has a complex surface in which some of the formed two-stage convex portion are glossy regions and the remaining portions are non-glossy regions, and thus it is possible to provide a complex and impressive design.

The synthetic resin skin material 34 shown in FIG. 5( c) can be used as a skin layer, which is a specific resin layer, and can be laminated with any other layer, such as an adhesive layer, a base layer, or the like, to obtain a skin material having a multilayer structure as shown in FIG. 1.
The method for producing the multi-layered skin material is not limited to the above method.

The present invention will be specifically explained below with reference to examples, but the present invention is not limited to these.

Example 1
(1. Manufacturing of molds)
The surface of a metal substrate, which was an iron metal roll having a diameter of 240 mm, was plated with copper to produce a copper-plated roll covered with a copper plating layer having a thickness of 150 μm (Step A).
Next, in order to remove the gloss, the entire surface of the roll was subjected to a sandblasting treatment (matte treatment) using alumina particles no. 180 to roughen the surface (Step B).
An etching resist was formed according to the design to be formed on the roughened copper-plated roll, and a design pattern was engraved to a depth of 60 μm by an etching method to form recesses (step C).Then, the etching resist was peeled off to obtain a mold precursor having a surface with roughened protrusions and smoothed recesses, i.e., unevenness, glossy regions, and non-glossy regions (step D).
Finally, the obtained mold precursor was plated with chrome to complete an embossing roll as a mold (step E).

(2. Manufacturing synthetic resin skin material using a mold)
In a calendering device, 2 kg of pigment (carbon black) was added to 100 kg of PVC resin [straight resin with a degree of polymerization of 800], and the mixture was heated to 200° C. and formed into a sheet by a calendering method so that the thickness after drying would be 200 μm, thereby obtaining a base layer containing a colorant.
In a separate process from the production of the base layer, 100 kg of PVC resin (straight resin with a degree of polymerization of 800) was heated to 200° C. and formed into a sheet by a calendaring method so that the thickness after drying would be 80 μm, thereby obtaining a skin layer.

Then, the skin layer obtained in the above process was brought into contact with the base layer obtained in the above process, and a laminate embossing process was performed by bringing the skin layer side into contact with the embossing roll, using one of a pair of embossing rolls, which is the roll-shaped mold obtained above, to form a skin layer having irregularities, glossy regions, and non-glossy regions on the surface, thereby obtaining the synthetic resin skin material of Example 1 (Process G).

Figure 6 is an optical photograph showing the synthetic resin skin material of Example 1, in which one level of unevenness is formed in the skin layer, and the top surfaces of the convexities have glossy regions. As shown in Figure 6, the skin material of Example 1 has a lattice pattern formed with one level of unevenness, with the top surfaces of the convexities of the lattice pattern being glossy regions, and the bottom surfaces of the concaves being non-glossy regions.

Example 2
(1. Manufacturing of molds)
The surface of an aluminum metal roll (metal substrate) having a diameter of 203.9 mm was subjected to a copper plating treatment to prepare a copper-plated roll covered with a copper plating layer having a thickness of 150 μm (Step A).
Thereafter, a design pattern serving as a base was engraved to a depth of 35 μm by an etching method to form recesses (step F).
Next, as a matte treatment, the entire surface of the roll on which the irregularities were formed was subjected to a sandblasting treatment with glass beads No. 280 to roughen the surface (step B).
Thereafter, in order to form a design pattern with a glossy finish, an etching resist was formed on the non-glossy area, and a recess with a depth of 15 μm was engraved by an etching method (Step C). The etching resist was peeled off to obtain an embossed mold, which is a mold precursor, having a total depth of 50 μm of unevenness and a smooth bottom surface of the recess (Step D).
Thereafter, the obtained mold precursor was subjected to chrome plating (step E) to complete the embossing mold.
The copper plating layer with the embossed pattern engraved on it was peeled off from the aluminum metal roll, and the peeled off copper plating layer was attached to a stainless steel metal plate (size 400 mm x 550 mm) to prepare a flat mold.

(2. Manufacturing synthetic resin skin material using a mold)
Instead of the embossing roll used in Example 1, the flat plate-shaped mold obtained above was used to form projections and recesses on the surface layer by press working.
That is, a skin layer formed in the same manner as in Example 1 was laminated in contact with a base layer formed in the same manner as in Example 1, and the skin layer of the laminate of the laminated skin layer and base layer was placed on the mold side and pressed to form a skin layer having irregularities, glossy regions and non-glossy regions on the surface, thereby obtaining the synthetic resin skin material of Example 2 (Step G).

Figure 7 is an optical photograph showing the synthetic resin skin material of Example 2, in which two stages of unevenness are formed in the skin layer, with the top surfaces of the highest parts of the protrusions having glossy regions. As shown in Figure 7, a wave pattern is engraved in the first stage, and the bottom surface of the wave pattern is a non-glossy region due to the roughening treatment, which appears gray in Figure 7. Then, in the second stage of engraving, deeper recesses are formed in the mold by etching, and the bottom surfaces of the recesses become smooth regions. The black parts in the skin layer shown in Figure 7 indicate the top surfaces of the protrusions, which have glossy surfaces due to the recesses formed in the second stage of engraving.

Example 3
In a calendering device, 2 kg of pigment (carbon black) was added to 100 kg of PVC resin (straight resin with a degree of polymerization of 800), and while heating at 200°C, the mixture was formed into a sheet by a calendering method so that the thickness after drying would be 150 μm, thereby obtaining a synthetic resin layer containing a colorant.
The obtained synthetic resin layer was pressed using the flat mold prepared in Example 2 to form a specific resin layer having an uneven surface, glossy regions and non-glossy regions (Step G) to obtain the synthetic resin skin material of Example 3. The synthetic resin skin material of Example 3 is a single-layer skin material consisting of only the specific resin layer.

Comparative Example 1
A skin material of Comparative Example 1 was obtained in the same manner as in Example 1, except that instead of the embossing roll that was the mold used in Example 1, an embossing roll was used that had been prepared by engraving a design pattern to a depth of 60 μm by electroforming mill embossing engraving on a metal base material that had been copper-plated in the same manner as in Example 1, and then chrome-plating the same.

Comparative Example 2
Instead of the embossing roll used as the mold in Example 1, a metal substrate plated with copper in the same manner as in Example 1 was engraved with a two-stage design pattern at a depth of 35 μm and then at a depth of 15 μm in the same manner as in Example 2 by two-stage etching engraving, and then the entire surface of the roll on which the unevenness was formed was subjected to a sandblasting treatment with alumina particles No. 180 to roughen the surface, thereby obtaining a mold precursor. The obtained mold precursor was subjected to a chrome plating treatment to obtain an embossing roll. A skin material of Comparative Example 2 was obtained in the same manner as in Example 1, except that the obtained embossing roll was used.

(Evaluation of synthetic resin skin materials)
(1. Gross Measurement)
For the obtained skin materials of Examples 1 to 3, Comparative Example 1, and Comparative Example 2, the 60° specular gloss (Gs(60°)) of the glossy area (gloss part) and the non-glossy area (matte part) of the surface of the skin layer was measured in accordance with JIS Z 8741 (1997), and the specular gloss of the glossy area (glossy part: gloss part), the specular gloss of the non-glossy area (non-glossy part: matte part), and the difference between the specular gloss of the glossy part and the specular gloss of the non-glossy part were calculated. The results are shown in Table 1 below. In Table 1, "60° specular gloss" is referred to as "gloss".

(2. Visual Evaluation)
The appearance of the skin material was visually evaluated, and the design due to the difference between the glossy area and the non-glossy area was evaluated according to the following criteria.
-standard-
A: The uneven pattern is well formed, and the difference between the glossy and non-glossy areas is clear.
B: The formability of the uneven pattern is good, but the difference between the glossy and non-glossy areas is unclear.
C: The formability of the uneven pattern is poor, and the difference between the glossy and non-glossy areas is unclear.

As can be seen from the results in Table 1, the synthetic resin skin materials of Examples 1 to 3 have a clear ability to form unevenness and have a clear difference in appearance between the glossy and non-glossy areas, achieving complex designs.
On the other hand, the synthetic resin skin material of Comparative Example 1 had unevenness but was entirely non-glossy, and had an appearance similar to that of known skin materials. The synthetic resin skin material of Comparative Example 2 had a complex uneven shape but was entirely non-glossy, and did not have the appearance advantage of having partial glossy areas.

10 Synthetic resin skin material 12 Base material layer 14 Adhesive layer 16 Skin layer (skin layer as specific resin layer)
20 Metal substrate for mold production 22 Etching resist 24, 26, 32 Mold (mold for forming synthetic resin skin material)
30 Chromium plating layer 34 Synthetic resin skin material (specific resin layer)
a) Glossy area (glossy area of specific resin layer)
b) Non-glossy region (non-glossy region of specific resin layer)

Claims (2)

A process A for subjecting a surface of a metal substrate for mold production to a copper plating treatment;
A step F of forming projections and recesses as a base pattern on the surface of the metal base material for mold production by using at least one means selected from laser engraving, mechanical engraving, electronic engraving, and etching;
A process B of subjecting the surface of the metal base material for mold production, which has been copper-plated to form an uneven surface as a base pattern, to a matte treatment;
A process C of forming an etching resist on the surface of the metal base material for mold production that has been subjected to a matte treatment in accordance with a design to be formed, and then performing an etching process to form recesses in areas where the etching resist is not formed;
Step D of removing the etching resist to obtain a mold precursor having a surface having projections and recesses and glossy and non-glossy areas; and
A method for producing a mold for forming a synthetic resin skin material, comprising: a step E of subjecting the surface of the obtained mold precursor to a chrome plating treatment to obtain a mold. a step G of contacting a resin composition for forming a synthetic resin layer, which comprises at least one resin selected from the group consisting of PVC resin, fluororesin, and acrylic resin, with the mold obtained by the method for producing a mold for forming a synthetic resin skin material according to claim 1, and then heating and pressing the mold to transfer the surface shape of the mold to the resin composition for forming a synthetic resin layer, thereby forming a synthetic resin layer having projections and recesses on one side;
and forming a base layer containing a thermoplastic resin and a colorant on a surface of the synthetic resin layer that does not have irregularities.