JP7750519B2 - Artificial skin and method for producing artificial skin - Google Patents

Description

The present invention relates to artificial skin, a method for producing artificial skin, and a coating liquid set for artificial skin.

Patent document 1 discloses a three-dimensional solid model for surgical simulation that includes a surface layer made of an elastic material and a lower layer arranged adjacent to the surface layer and made of an elastic material having an elastic modulus different from that of the elastic material that makes up the surface layer.
Patent Document 2 discloses transparent artificial skin for suturing practice, which includes a thin epidermal layer formed to imitate the epidermis of skin, a dermal layer formed to be thicker than the epidermal layer to imitate the dermis of skin, and a subcutaneous layer formed to be thicker than the dermal layer to imitate the subcutaneous tissue of skin.

JP 2017-107189 A International Publication No. 2015/189954

Artificial skin made of elastic materials exists and is used in humanoid robots, medical simulators, etc. It is desirable for such artificial skin to be less sticky, have a texture similar to human skin, and be highly resistant to external stress. However, depending on the material of the artificial skin, plasticizers contained in the artificial skin may seep out onto the surface, causing stickiness or tearing due to external stress.
The present invention aims to realize artificial skin that is less sticky and has high toughness against external stress.

According to the present invention, the following inventions (1) to (10) are provided.
(1) An artificial skin comprising: an elastic layer made of an elastic material having a silicone content of 20% by mass or less relative to the total solid content of the elastic layer; a skin layer made of an acrylic resin and laminated on the elastic layer; and spherical particles attached to the surface of the skin layer opposite the elastic layer , the spherical particles having an average particle diameter of 1 μm or more and 30 μm or less .
(2) The artificial skin described in (1), characterized in that the elastic layer contains a urethane-based elastomer.
(3) The artificial skin described in (1), characterized in that the elastic layer contains an acrylic elastomer.
(4) The artificial skin according to any one of (1) to (3), characterized in that the elastic layer does not contain a plasticizer.
(5) The artificial skin described in any one of (1) to (4), characterized in that the elastic layer contains a colorant, and the epidermal layer and the spherical particles do not contain a colorant.
(6) The artificial skin according to any one of (1) to (5), characterized in that the contact angle of water on the surface of the epidermal layer is 100° or less.
(7) The artificial skin described in any one of (1) to (6), characterized in that the spherical particles have an average particle diameter of 10% or more and 50% or less of the thickness of the epidermal layer.
(8) The artificial skin described in any one of (1) to (7), characterized in that the spherical particles are made of resin.
(9) A method for manufacturing artificial skin, comprising the steps of: curing a solution containing an acrylic resin to form an adhesive epidermal layer; forming an elastic layer on the epidermal layer, the elastic layer being made of an elastic material having a silicone content of 20 mass% or less relative to the total solid content of the elastic layer; and attaching spherical particles having an average particle diameter of 1 μm or more and 30 μm or less to the surface of the epidermal layer opposite the elastic layer.
(10) Artificial skin comprising an elastic layer made of an elastic material having a silicone content of 20% by mass or less relative to the total solid content of the elastic layer; a skin layer made of an acrylic resin and laminated on the elastic layer; and spherical particles attached to the surface of the skin layer opposite the elastic layer, the spherical particles having an average particle diameter of 10% to 50% of the thickness of the skin layer.

The present invention makes it possible to create artificial skin that is less sticky and highly resistant to external stress.

1 is a diagram showing an example of the configuration of artificial skin to which the present embodiment is applied. FIG. FIG. 1 is a diagram showing steps in a method for manufacturing artificial skin. 1A to 1C are diagrams showing an example of the procedure of each step in a method for producing artificial skin.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.
(Artificial skin 1)
FIG. 1 is a diagram showing an example of the configuration of artificial skin 1 to which this embodiment is applied, and is a diagram showing a cross section of the artificial skin 1.
The artificial skin 1 of this embodiment is used, for example, as the skin of a humanoid robot. The artificial skin 1 of this embodiment is also used, for example, in a medical simulator for practicing medical procedures such as injections, surgery, cardiac massage, etc. However, the uses of the artificial skin 1 are not limited to these.

As shown in Figure 1, the artificial skin 1 comprises an elastic layer 10, an epidermal layer 20 laminated on the elastic layer 10, and spherical particles 30 attached to the surface of the epidermal layer 20 opposite the elastic layer 10. In the following description, the surface of the artificial skin 1 to which the spherical particles 30 are attached (the upper surface in Figure 1) may be referred to as the surface of the artificial skin 1.

(Elastic layer 10)
The elastic layer 10 is made of an elastic material. The elastic layer 10 preferably contains a thermoplastic elastomer as the elastic material. A thermoplastic elastomer is a polymer that has hard segments and soft segments, has rubber elasticity at room temperature, and softens and becomes fluid when heated.
In the elastic layer 10 of this embodiment, the content of the thermoplastic elastomer is preferably 90% by mass or more, and more preferably 95% by mass or more, of the total mass of the elastic layer 10. There is no particular upper limit to the content of the thermoplastic elastomer in the elastic layer 10, but the content of the thermoplastic elastomer may be 100% by mass.

Examples of thermoplastic elastomers contained in the elastic layer 10 include urethane-based elastomers, acrylic-based elastomers, olefin-based elastomers, vinyl chloride-based elastomers, butadiene-based elastomers, styrene-based elastomers, ester-based elastomers, amide-based elastomers, and silicone-based elastomers. Among these thermoplastic elastomers, it is more preferable that the elastic layer 10 contain a urethane-based elastomer or an acrylic-based elastomer.

By including a urethane-based elastomer or an acrylic-based elastomer as the elastic material, the elastic layer 10 can improve adhesion between the elastic layer 10 and the epidermis layer 20 compared to, for example, when the elastic material includes other thermoplastic elastomers. This makes it less likely that the epidermis layer 20 will peel off from the elastic layer 10 in the artificial skin 1.

The elastic layer 10 of this embodiment has a silicone content of 20% by mass or less, based on the total solid content of the elastic layer 10. If the elastic layer 10 contains silicone in an amount exceeding 20% by mass, based on the total solid content, it becomes difficult to achieve adhesion between the elastic layer 10 and the epidermis layer 20. In this case, repeated bending and stretching of the artificial skin 1 will make the elastic layer 10 and the epidermis layer 20 more likely to peel from each other. From a higher perspective, the silicone content in the elastic layer 10 is preferably 15% by mass or less, based on the total solid content of the elastic layer 10, and more preferably 10% by mass or less.

The urethane elastomer contained in the elastic layer 10 is a block copolymer having a urethane bond, which is a copolymerization of an isocyanate, a short-chain diol, and a long-chain polyol. The urethane elastomer has a hard segment composed of a diisocyanate and a short-chain diol, and a soft segment composed of a diisocyanate and a long-chain polyol.
The short-chain diol is, for example, a diol having a molecular weight of 500 or less.
The long-chain polyol is a polyol having a number average molecular weight of about 1,000 to 4,000, and examples thereof include polyester polyol, polyether polyol, and polycarbonate polyol.
Examples of diisocyanates include aromatic diisocyanates, aliphatic diisocyanates, and alicyclic diisocyanates. More specifically, aromatic diisocyanates such as diphenylmethane diisocyanate (MDI) and aliphatic diisocyanates such as hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI) can be used.

In the artificial skin 1 of this embodiment, the elastic layer 10 contains a urethane-based elastomer as the elastic material, which makes it easier to achieve a texture closer to that of human skin than when other elastic materials are used. Additionally, in the artificial skin 1 of this embodiment, by adjusting the average molecular weights of the hard and soft segments of the urethane-based elastomer contained in the elastic layer 10, it becomes easier to achieve the desired elastic force and tensile strength of the elastic layer 10, making it easier to achieve a texture closer to that of human skin.
Artificial skin 1 in which elastic layer 10 contains a urethane-based elastomer as the elastic material is particularly suitable for use as the skin of humanoid robots, etc., where the feel of artificial skin 1 is likely to have an impact on usability, sales, etc.

The acrylic elastomer contained in the elastic layer 10 may be a block copolymer in which the hard segment is made of (meth)acrylic acid ester and the soft segment is made of acrylonitrile, ethylene, (meth)acrylic acid ester, etc. In the description of this embodiment, "(meth)acrylic" means at least one of acrylic and methacrylic.
A specific example of such an acrylic elastomer is a block copolymer in which the hard segment is composed of methyl methacrylate (MMA) and the soft segment is composed of butyl acrylate (BA) and 2-ethylhexyl acrylate (2EHA).

In the artificial skin 1 of this embodiment, the elastic layer 10 contains an acrylic elastomer as the elastic material, which increases the toughness of the artificial skin 1 compared to when other elastic materials are used. This prevents the artificial skin 1 from tearing when external stress is applied to the artificial skin 1.
Artificial skin 1 in which elastic layer 10 contains acrylic elastomer as the elastic material can be particularly suitably used in, for example, medical simulators where stress is likely to be applied to artificial skin 1 .

The elastic layer 10 may also contain additives in addition to the thermoplastic elastomer described above. Examples of additives that may be contained in the elastic layer 10 include curing agents, colorants, antioxidants, UV absorbers, light stabilizers, heat stabilizers, and flame retardants.

In this embodiment, the elastic layer 10 preferably contains a colorant as an additive. By including a colorant in the elastic layer 10, it becomes possible to color the artificial skin 1 to a desired color, such as a color similar to that of human skin. Furthermore, compared to when the elastic layer 10 does not contain a colorant and the artificial skin 1 is colored by including a colorant in the epidermal layer 20 or the spherical particles 30, the colorant is less likely to be exposed to the surface of the artificial skin 1. This prevents the colorant from adhering to and contaminating objects that come into contact with the surface of the artificial skin 1 or the user's body.
Furthermore, in the artificial skin 1, the elastic layer 10 is visible through the epidermal layer 20 and the spherical particles 30. In the artificial skin 1, the color of the elastic layer 10 colored with a coloring agent is scattered by the epidermal layer 20 and the spherical particles 30 and is visible to the user, making it easier to reproduce a color close to that of human skin.

The colorant contained in the elastic layer 10 is not particularly limited, but may be a pigment or a dye, with pigments being preferred. Furthermore, one type of colorant may be used alone, or multiple types may be used in combination.

As mentioned above, the elastic layer 10 may contain additives, but it is more preferable that it does not contain a plasticizer as an additive. If the elastic layer 10 contains a plasticizer, the surface of the artificial skin 1 may become sticky if the plasticizer seeps out onto the surface of the artificial skin 1. In contrast, if the elastic layer 10 does not contain a plasticizer, the surface of the artificial skin 1 is less likely to become sticky than if the elastic layer 10 contains a plasticizer.

The thickness of the elastic layer 10 varies depending on the application of the artificial skin 1, but can be, for example, 0.5 mm or more and 20 mm or less. The thickness of the elastic layer 10 is preferably greater than the thickness of the epidermis layer 20. In the artificial skin 1 of this embodiment, the "thickness" refers to the thickness in the direction in which the epidermis layer 20 is stacked on the elastic layer 10 (i.e., the vertical direction in FIG. 1 ).
For example, when the artificial skin 1 is used as a medical simulator, the thickness of the elastic layer 10 is preferably 4 mm or more. In a medical simulator, for example, the artificial skin 1 may be pierced with an instrument such as a syringe or cut open with a scalpel. In this embodiment, by making the thickness of the elastic layer 10 4 mm or more, it becomes difficult for instruments such as a syringe or scalpel to penetrate the artificial skin 1, and the artificial skin 1 is less likely to be damaged.

The storage modulus of the elastic layer 10 at 23° C. is preferably 1 kPa or more and 1000 kPa or less, more preferably 10 kPa or more and 500 kPa or less, and even more preferably 50 kPa or more and 200 kPa or less.
This makes the artificial skin 1 feel more similar to human skin.

The elastic layer 10 preferably has a tensile strength at break at 23° C. of 10 MPa or more and 10,000 MPa or less, and more preferably 100 MPa or more and 5,000 MPa or less.
The elastic layer 10 preferably has a tensile elongation at break of 500% or more, and more preferably 700% or more, at 23° C. The higher the tensile elongation at break of the elastic layer 10, the better. There is no particular upper limit, but it is usually 3000% or less.
The Young's modulus of the elastic layer 10 at 23° C. is preferably 0.01 MPa or more and 10 MPa or less, more preferably 0.1 MPa or more and 5 MPa or less, and even more preferably 0.3 MPa or more and 2 MPa or less.
When the tensile breaking strength, tensile breaking elongation, and Young's modulus of the elastic layer 10 are within the above ranges, the artificial skin 1 has sufficient flexibility and is prevented from tearing or breaking even when repeatedly bent and stretched.

(Epidermal layer 20)
The surface layer 20 of this embodiment is made of an acrylic resin. Here, the acrylic resin refers to a resin containing, as a structural unit, a structural unit derived from one or more monomers selected from the group consisting of (meth)acrylic acid esters.
The surface layer 20 of this embodiment preferably has adhesiveness. In addition, the surface layer 20 of this embodiment preferably contains an acrylic adhesive as the acrylic resin.

The acrylic resin constituting the skin layer 20 contains a (meth)acrylic copolymer component.
The (meth)acrylic copolymer component is a copolymer mainly composed of structural units derived from (meth)acrylic monomers. The term "main component" means that the content of structural units derived from (meth)acrylic monomers in the (meth)acrylic copolymer component is 50% by mass or more. The content of structural units derived from (meth)acrylic monomers in the (meth)acrylic copolymer component is preferably 80% by mass or more, and more preferably 90% by mass or more.

As the (meth)acrylic monomer, for example, a (meth)acrylate monomer can be used. In the description of this embodiment, "(meth)acrylate" means at least one of acrylate and methacrylate.
Examples of (meth)acrylate monomers include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, cyclohexyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. These may be used alone or in combination.

The acrylic resin constituting the skin layer 20 may contain a crosslinking agent. When the acrylic resin contains a crosslinking agent, the skin layer 20 exerts sufficient cohesive force and exhibits excellent flexibility.
Examples of crosslinking agents include isocyanate-based crosslinking agents made of polyisocyanate having multiple isocyanate groups in the molecule, epoxy-based crosslinking agents made of epoxy resin having multiple glycidyl groups in the molecule, and metal chelate-based crosslinking agents made of metal chelate compounds. These crosslinking agents may be used alone or in combination. Among these, from the viewpoint of being able to crosslink without heating at high temperatures, it is preferable to use an isocyanate-based crosslinking agent or a metal chelate-based crosslinking agent, and it is particularly preferable to use a metal chelate-based crosslinking agent. By using a metal chelate-based crosslinking agent, the curing time required to prepare the epidermis layer 20 in the manufacturing process of the artificial skin 1 described below can be shortened, thereby improving the productivity of the artificial skin 1.

The skin layer 20 may contain a tackifier in addition to the acrylic adhesive. When the skin layer 20 contains a tackifier, the adhesiveness of the skin layer 20 is improved, and the spherical particles 30 are less likely to peel off from the surface of the skin layer 20. Furthermore, when the skin layer 20 contains a tackifier, the adhesion between the elastic layer 10 and the skin layer 20 can be further improved.
The tackifier contained in the skin layer 20 is not particularly limited, but examples thereof include hydrogenated rosin resin, hydrogenated terpene resin, aliphatic hydrocarbon resin, and silane coupling agent.

In addition to the acrylic adhesive, crosslinking agent, and tackifier, the skin layer 20 may contain additives such as softeners, antioxidants, ultraviolet absorbers, light stabilizers, heat stabilizers, and flame retardants.
The epidermis layer 20 may or may not contain a colorant as an additive, but it is preferable that it does not contain a colorant from the viewpoint of making the appearance of the artificial skin 1 similar to that of human skin. Furthermore, if the epidermis layer 20 contains a colorant, the colorant is likely to be exposed on the surface of the artificial skin 1, and there is a risk that the colorant will adhere to and stain objects that come into contact with the surface of the artificial skin 1 or the user's body.

Furthermore, it is preferable that the epidermis layer 20 is transparent to visible light. In the artificial skin 1 of this embodiment, since the epidermis layer 20 is transparent to visible light, when the elastic layer 10 is colored, the color of the elastic layer 10 can be seen from the surface of the artificial skin 1 through the epidermis layer 20 and the spherical particles 30 described below. This makes it easier to give the artificial skin 1 a desired color, such as a color similar to human skin.

The thickness of the skin layer 20 can be, for example, 20 μm or more and 1 mm or less.
The thickness of the epidermis layer 20 is preferably thinner than the thickness of the elastic layer 10. If the thickness of the epidermis layer 20 is thicker than the thickness of the elastic layer 10, the flexibility of the artificial skin 1 may decrease, and the feel of the artificial skin 1 may become worse.
Furthermore, the thickness of the epidermis layer 20 is preferably thicker than the average particle diameter of the spherical particles 30, and more preferably is at least two times but not more than 100 times the average particle diameter of the spherical particles 30. If the thickness of the epidermis layer 20 is thinner than the average particle diameter of the spherical particles 30, the spherical particles 30 will be more likely to peel off from the surface of the epidermis layer 20. On the other hand, if the thickness of the epidermis layer 20 is excessively thick compared to the average particle diameter of the spherical particles 30, the spherical particles 30 will be more likely to be embedded inside the epidermis layer 20, and the effect of improving the tactile feel of the artificial skin 1 due to the presence of the spherical particles 30 in the artificial skin 1 may be insufficient.

The storage modulus of the skin layer 20 at 23° C. is preferably 1 kMPa or more and 1000 kPa or less, more preferably 10 kPa or more and 500 kPa or less, and even more preferably 50 kPa or more and 200 kPa or less.
This makes the feel of the artificial skin 1 closer to that of human skin, and also prevents the spherical particles 30 from being embedded in the epidermal layer 20 and becoming sticky.
Furthermore, the absolute value of the difference in storage modulus at 23° C. between the elastic layer 10 and the epidermis layer 20 is preferably 1000 kPa or less, and more preferably 100 kPa or less. Additionally, the smaller the absolute value of the difference in storage modulus at 23° C. between the elastic layer 10 and the epidermis layer 20, the more preferable. This prevents the epidermis layer 20 from lifting or peeling off from the elastic layer 10 even when the artificial skin 1 is repeatedly bent and stretched.

The skin layer 20 preferably has a tensile breaking strength at 23° C. of 10 MPa or more and 10,000 MPa or less, and more preferably 100 MPa or more and 5,000 MPa or less.
The elastic layer 10 preferably has a tensile breaking elongation of 500% or more, more preferably 700% or more, at 23° C. The higher the tensile breaking elongation of the skin layer 20, the better. There is no particular upper limit, but it is usually 3000% or less.
The Young's modulus of the skin layer 20 at 23° C. is preferably 0.01 MPa or more and 10 MPa or less, more preferably 0.1 MPa or more and 5 MPa or less, and even more preferably 0.3 MPa or more and 2 MPa or less.
When the tensile breaking strength, tensile breaking elongation, and Young's modulus of the epidermis layer 20 are within the above ranges, the artificial skin 1 has sufficient flexibility and is less likely to tear or break even when repeatedly bent and stretched.

The adhesive strength of the epidermis layer 20 to the acrylic plate is preferably 10 N/25 mm or more, more preferably 12 N/25 mm or more, and even more preferably 15 N/25 mm or more. When the adhesive strength of the epidermis layer 20 to the acrylic plate is 10 N/25 mm or more, the adhesive strength of the spherical particles 30 to the epidermis layer 20 is higher than when the adhesive strength to the acrylic plate is less than 10 N/25 mm. This makes it difficult for the spherical particles 30 to peel off from the surface of the epidermis layer 20 in the artificial skin 1. In particular, when the spherical particles 30 are resin particles made of resin, the spherical particles 30 are difficult to peel off from the surface of the epidermis layer 20.
The adhesive strength of the skin layer 20 to the acrylic plate can be measured by the following method in accordance with the method described in the Test Method for Adhesive Tapes and Adhesive Sheets (JIS Z 0237 (2009)). Specifically, for example, the skin layer 20 formed on a substrate or the like is attached to an acrylic plate with a surface roughness of 50±25 nm. Then, using a tensile tester, the skin layer is peeled off in a direction 180° relative to the acrylic plate at a speed of 5 mm/s, and the force required to peel off is taken as the adhesive strength to the acrylic plate.

(Spherical particles 30)
The spherical particles 30 are particles having a spherical shape. By using spherical particles in the artificial skin 1, the texture of the artificial skin 1 becomes closer to that of human skin. Here, spherical does not only mean a perfect sphere, but also an elliptical or nearly spherical shape, or a shape with minute holes or irregularities on the surface. The spherical particles 30 are preferably spherical if the ratio of the minor axis to the major axis is in the range of 1:1 to 1:2. It is more preferable that the spherical particles are perfect spheres, as this will result in a uniform texture and gloss on the surface of the artificial skin 1.
The spherical particles 30 may be inorganic particles or resin particles as long as they are spherical, but from the viewpoint of transparency, resin particles are preferred.

Examples of resin particles used as the spherical particles 30 include resin particles made of resins such as (meth)acrylic resin, styrene resin, styrene-(meth)acrylic resin, urethane resin, polyamide resin, silicone resin, epoxy resin, phenolic resin, polyethylene resin, and cellulose. These may be used alone or in combination of two or more types as resin particles.
Of these resins, the spherical particles 30 are preferably particles made of a (meth)acrylic resin or a styrene resin from the viewpoint of adhesion to the skin layer 20. Examples of such spherical particles 30 include (meth)acrylic particles (acrylic beads), acrylic urethane particles (acrylic urethane beads), acrylic styrene particles (acrylic styrene beads), and styrene particles (styrene beads).

The spherical particles 30 are preferably hard. Specifically, the 10% compressive strength of the spherical particles 30 is preferably 10 MPa or more, more preferably 12 MPa or more, and even more preferably 15 MPa or more. When the 10% compressive strength of the spherical particles 30 is 10 MPa or more, the tactile feel on the surface of the artificial skin 1 is improved. The 10% compressive strength of the spherical particles 30 refers to the hardness when the spherical particles 30 are compressed 10%, and can be measured using an MCT series microcompression tester manufactured by Shimadzu Corporation. Specifically, it is obtained by squeezing the spherical particles 30 until their diameter becomes 90% of their length and measuring the pressure at that time. Examples of (meth)acrylic particles or styrene particles that are hard spherical particles 30 include cross-linked polymethyl methacrylate particles, cross-linked polybutyl methacrylate particles, and cross-linked polystyrene particles.

The spherical particles 30 are attached to the surface of the skin layer 20 opposite the elastic layer 10. In the following description, the surface of the skin layer 20 opposite the elastic layer 10 to which the spherical particles 30 are attached may be referred to as the surface of the skin layer 20.

In this embodiment, the spherical particles 30 adhere to the surface of the epidermal layer 20 due to the adhesive force of the epidermal layer 20. Furthermore, the spherical particles 30 adhere to the surface of the epidermal layer 20 so that a portion of the spherical particles 30 protrudes from the surface of the epidermal layer 20. As a result, the surface of the artificial skin 1 has a rough surface with fine irregularities resulting from the shape of the spherical particles 30.

In the artificial skin 1 of this embodiment, spherical particles 30 are attached to the surface of the epidermal layer 20, so that the surface condition of the artificial skin 1 can be made closer to that of human skin.
Specifically, the artificial skin 1 has spherical particles 30 attached to the surface of the epidermis layer 20, which makes it less likely to become sticky due to the elastic material that makes up the elastic layer 10 and the acrylic resin that makes up the epidermis layer 20. This makes the feel of the artificial skin 1 closer to that of human skin.
Furthermore, since the spherical particles 30 are attached to the surface of the epidermal layer 20 of the artificial skin 1, when an instrument such as a syringe is inserted into the surface of the artificial skin 1, the mark left by the instrument is less noticeable.

Furthermore, since the artificial skin 1 has spherical particles 30 attached to the surface of the epidermal layer 20, light irradiated onto the surface of the artificial skin 1 from outside the artificial skin 1 is more likely to be scattered by the spherical particles 30. This reduces the glossiness of the surface of the artificial skin 1, making it easier to achieve an appearance similar to that of human skin.
Furthermore, since the spherical particles 30 are attached to the surface of the epidermal layer 20 of the artificial skin 1, the wettability of the surface of the artificial skin 1 is increased compared to when the spherical particles 30 are not attached. This makes it easier to apply cosmetics, paints, etc. to the surface of the artificial skin 1, facilitating decoration of the artificial skin 1. In addition, cosmetics, etc. applied to the surface of the artificial skin 1 are less likely to peel off.

The average particle diameter of the spherical particles 30 can be 1 μm or more and 30 μm or less, and preferably 5 μm or more and 20 μm or less. The average particle diameter of the spherical particles 30 is preferably smaller than the thickness of the skin layer 20, and more preferably 1% or more and 50% or less of the thickness of the skin layer 20.
This makes it difficult for the spherical particles 30 to be embedded in the skin layer 20, compared to when the average particle diameter of the spherical particles 30 is smaller than this range. Also, it makes it difficult for the spherical particles 30 to peel off from the surface of the skin layer 20, compared to when the average particle diameter of the spherical particles 30 is larger than this range.
In this embodiment, the average particle size of the spherical particles 30 refers to the number-average particle size. The average particle size of the spherical particles 30 can be measured by, for example, a laser diffraction scattering method.

Furthermore, it is preferable that the spherical particles 30 of this embodiment do not contain a colorant.
Furthermore, it is preferable that the spherical particles 30 are transparent to visible light. In the artificial skin 1 of this embodiment, since the spherical particles 30 are transparent to visible light, when the elastic layer 10 is colored, the color of the elastic layer 10 can be seen from the surface of the artificial skin 1 through the epidermal layer 20 and the spherical particles 30. This makes it easier to give the artificial skin 1 a desired color, such as a color similar to human skin.

(Characteristics of Artificial Skin 1)
As described above, the artificial skin 1 of this embodiment includes the elastic layer 10, the epidermis layer 20 laminated on the elastic layer 10, and the spherical particles 30 attached to the surface of the epidermis layer 20 opposite the elastic layer 10. The epidermis layer 20 of the artificial skin 1 is formed from an acrylic resin. Therefore, the adhesion of the spherical particles 30 to the surface of the epidermis layer 20 is higher than when, for example, the epidermis layer 20 is formed from a material other than an acrylic resin. This makes it difficult for the spherical particles 30 to peel off from the surface of the epidermis layer 20.
Furthermore, even if the artificial skin 1 is used repeatedly, the tactile sensation is not easily lost and good condition can be maintained for a long period of time.

(Method for manufacturing artificial skin 1)
Next, a method for manufacturing the artificial skin 1 of this embodiment will be described. FIG. 2 is a diagram showing steps in the method for manufacturing the artificial skin 1.
As shown in FIG. 2, the method for producing artificial skin 1 of this embodiment includes a step of curing a solution containing an acrylic resin to form an adhesive epidermal layer 20 (epidermal layer forming step S1), a step of forming an elastic layer 10 made of an elastic material on epidermal layer 20 (elastic layer forming step S2), and a step of attaching spherical particles 30 to the surface of epidermal layer 20 opposite to elastic layer 10 (particle attaching step S3).

The procedure for the elastic layer formation step in the method for manufacturing artificial skin 1 varies depending on the type of elastic material (type of thermoplastic elastomer) used for elastic layer 10. Here, the method for manufacturing artificial skin 1 will be described using an example in which a urethane-based elastomer is used for elastic layer 10.
3(a) to 3(c) are diagrams showing an example of the procedure of each step in the manufacturing method of artificial skin 1. Fig. 3(a) shows the epidermis layer forming step, Fig. 3(b) shows the elastic layer forming step, and Fig. 3(c) shows the particle attachment step.

(Skin layer formation step S1)
In the surface layer forming step S1, a support 50 made of a mold, a release film, or the like that has releasability with respect to the acrylic resin that constitutes the surface layer 20 is prepared.
Also, a surface layer coating liquid containing an acrylic resin is prepared for forming the surface layer 20. The surface layer coating liquid will be described in detail later.

3( a), the coating liquid for the surface skin layer is applied onto a support 50 having releasability to the acrylic resin. At this time, the coating liquid for the surface skin layer is applied so that the thickness of the coating liquid for the surface skin layer after drying will be the desired thickness of the surface skin layer 20.
The method for applying the coating liquid for the surface layer is not particularly limited, and examples thereof include a coating method using a coating machine such as a comma coater, a die coater, a curtain coater, a spray coater, a slit coater, a knife coater, etc. Alternatively, the coating liquid for the surface layer may be poured into the support 50 having releasability.

Next, the solvent in the surface layer coating liquid applied to the support 50 is evaporated, and the surface layer coating liquid is dried. The surface layer coating liquid may be heated as needed when drying. The surface layer coating liquid is then cured under a predetermined environment, resulting in a surface layer 20 with adhesive properties.

(Elastic layer forming step S2)
In the elastic layer forming step S2, a coating liquid for forming the elastic layer 10 is prepared. In this example, the coating liquid for forming the elastic layer contains a urethane-based elastomer, which is an example of a thermoplastic elastomer. The coating liquid for forming the elastic layer will be described in detail later.
Next, the elastic layer coating liquid is applied onto the surface skin layer 20 formed in the surface skin layer forming step S1. The elastic layer coating liquid may be applied using a coating machine, as in the surface skin layer forming step, or may be poured into the support 50.

Next, the solvent in the elastic layer coating liquid applied to the surface layer 20 is evaporated, and the elastic layer coating liquid is dried. The elastic layer coating liquid may be heated as needed when drying. This results in a laminate 40 in which the elastic layer 10 and the surface layer 20 are laminated. The resulting laminate 40 is then removed from the support.

In this example, the elastic layer coating liquid was applied or poured onto the surface layer 20 to form a laminate 40 in which the elastic layer 10 and the surface layer 20 were laminated, but the elastic layer formation process is not limited to this.
The laminate 40 may be produced, for example, by the following method. That is, the elastic layer coating liquid is applied or poured onto a support (not shown) other than the support 50 on which the skin layer 20 is formed, and then dried to form the elastic layer 10. The resulting elastic layer 10 and the skin layer 20 are then superimposed, and a load is applied as necessary to laminate them. This results in the laminate 40 in which the elastic layer 10 and the skin layer 20 are stacked.

(Particle attachment step S3)
In the particle attachment step S3, spherical particles 30 are sprinkled onto the surface of the skin layer 20 of the laminate 40 opposite the elastic layer 10. As described above, the skin layer 20 has adhesiveness. Therefore, by sprinkling the spherical particles 30 onto the skin layer 20 of the laminate 40, the spherical particles 30 adhere to the surface of the skin layer 20 opposite the elastic layer 10.
Next, the layered product 40 with the spherical particles 30 attached to the surface layer 20 is washed with water, thereby removing excess spherical particles 30 that are not attached to the surface of the surface layer 20 and are attached to other parts of the layered product 40.
Through the above steps, the artificial skin 1 shown in Figure 1 is obtained, which includes the elastic layer 10, the epidermis layer 20 laminated on the elastic layer 10, and the spherical particles 30 attached to the surface of the epidermis layer 20 opposite the elastic layer 10.

(Artificial skin coating liquid set)
Next, we will explain the artificial skin coating liquid set used to produce the artificial skin 1 of this embodiment. The artificial skin coating liquid set is used to form the artificial skin 1 including the elastic layer 10 and the epidermis layer 20, and includes a coating liquid for the elastic layer and a coating liquid for the epidermis layer.

(Coating liquid for elastic layer)
The elastic layer coating liquid is an example of a first coating liquid for forming the elastic layer 10 .
The coating liquid for the elastic layer contains a raw material of a thermoplastic elastomer, which is an elastic material that constitutes the elastic layer 10. As described above, examples of the thermoplastic elastomer include a urethane-based elastomer and an acrylic-based elastomer.

The elastic layer coating liquid used to form the elastic layer 10 made of a urethane-based elastomer contains, for example, a base resin containing a short-chain diol and a long-chain polyol, which are the raw materials for the urethane-based elastomer, and a curing agent made of an isocyanate or a metal chelate. The elastic layer coating liquid used to form the elastic layer 10 made of a urethane-based elastomer may be a two-component coating liquid in which the base resin and the curing agent are separate, or a one-component coating liquid in which both the base resin and the curing agent are included.

Furthermore, the coating liquid for the elastic layer for forming the elastic layer 10 made of a urethane-based elastomer may be a solvent-based coating liquid that is used by mixing with a solvent, or may be a solventless coating liquid that does not use a solvent.
When a solvent is used in the coating liquid for the elastic layer, the solvent is not particularly limited, but examples thereof include acetone, toluene, benzene, cyclohexane, hexane, methyl acetate, ethyl acetate, isopropyl acetate, propyl acetate, methyl isobutyl ketone, and methyl ethyl ketone.

The elastic layer coating liquid for forming the elastic layer 10 made of an acrylic elastomer is, for example, a solution containing an acrylic elastomer and a solvent that dissolves the acrylic elastomer.
As the solvent, acetone, toluene, benzene, cyclohexane, hexane, methyl acetate, ethyl acetate, isopropyl acetate, propyl acetate, methyl isobutyl ketone, methyl ethyl ketone, etc. can be used, as in the elastic layer coating liquid for forming the elastic layer 10 made of a urethane-based elastomer.

Furthermore, the coating liquid for the elastic layer may contain the various additives described above, if necessary.
The viscosity of the elastic layer coating liquid is preferably in the range of 10 mPa·s to 20 Pa·s. If the viscosity of the elastic layer coating liquid exceeds 20 Pa·s, the workability of applying or pouring the elastic layer coating liquid onto the surface layer 20 in the elastic layer formation step described above is likely to decrease. If the viscosity of the elastic layer coating liquid is less than 10 mPa·s, the elastic layer coating liquid is likely to flow around, for example, when applying the elastic layer coating liquid onto a release film. In this case, it may be difficult to achieve the desired thickness of the elastic layer 10.

(Coating liquid for surface layer)
The surface layer coating liquid is an example of a second coating liquid for forming the surface layer 20 .
The surface layer coating liquid contains an acrylic resin for forming the surface layer 20. As described above, the acrylic resin is a resin containing structural units derived from one or more monomers selected from the group consisting of (meth)acrylic acid esters.
The coating liquid for the surface layer also contains a crosslinking agent, such as an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, or a metal chelate-based crosslinking agent, as described above.
The coating liquid for the surface layer may be a two-component coating liquid containing the acrylic resin and the crosslinking agent separately, or may be a one-component coating liquid containing both the acrylic resin and the crosslinking agent.
The coating liquid for the surface layer may contain a solvent, similar to the coating liquid for the elastic layer.

The viscosity of the surface layer coating liquid is preferably in the range of 5 mPa·s to 10 Pa·s. If the viscosity of the surface layer coating liquid exceeds 10 Pa·s, the workability of applying or pouring the surface layer coating liquid onto the support 50 in the above-mentioned surface layer formation step is likely to decrease. If the viscosity of the surface layer coating liquid is less than 5 mPa·s, the surface layer coating liquid will tend to flow around, for example, when applying the surface layer coating liquid onto a release film. In this case, it may be difficult to achieve the desired thickness of the surface layer 20.

The coating fluid for the elastic layer and the coating fluid for the surface layer may be synthesized by known methods, or commercially available products may be used.

Next, the present invention will be described in more detail based on examples. Note that the present invention is not limited to the following examples.

<Preparation of Elastic Layer-Forming Composition>
(Elastic layer-forming composition a1)
16 g of "Sannyx PP-4000" manufactured by Sanyo Chemical Industries, Ltd. (polypropylene glycol, number average molecular weight 4000, viscosity 920 mPa·s, solid content concentration 100% by mass), 8.0 g of "Sannyx KC-737" manufactured by Sanyo Chemical Industries, Ltd. (glycerin-based polyether, number average molecular weight 7000, viscosity 1430 mPa·s, solid content concentration 100% by mass), and 8.0 g of "DOWSIL" manufactured by Dow-Toray 0.96 g of BY16-201 (both terminal carbinol-modified silicone oil, solids concentration 100% by mass), 2.6 g of Asahi Kasei Corporation's isocyanate-based crosslinking agent "Duranate D101" (HDI-based prepolymer polyisocyanate, solids concentration 100% by mass), 0.24 g of BYK-Chemie Corporation's defoamer "BYK-088" (silicone-based defoamer, solids concentration 3.3% by mass), and 0.24 g of Nitto Kasei's tin catalyst "Neostan U-810" (dioctyltin dilaurate, solids concentration 100% by mass) were mixed and stirred to prepare an elastic layer-forming composition a1. The viscosity of the prepared elastic layer-forming composition a1 was 1100 mPa s.

(Elastic layer-forming composition a2)
16 g of Kuraray Co., Ltd.'s acrylic elastomer "CLARITY LA3320" (an A-B-A block copolymer using methyl methacrylate for the hard block and normal butyl acrylate for the soft block, pellet-like solid material) was dissolved in 24 g of butyl acetate, and then 0.04 g of BYK-Chemie Co., Ltd.'s defoamer "BYK-051N" (a silicone-based defoamer, solids concentration 20% by mass) was added and stirred to prepare elastic layer-forming composition a2. The prepared elastic layer-forming composition a2 had a solids concentration of 40% by mass and a viscosity of 2500 mPa s.

(Elastic layer-forming composition a3)
A base material (90% by mass of polyol, 7% by mass of plasticizer, and 3% by mass of tin catalyst, based on the total amount of base material) of soft resin for molding (product name "Human Skin Gel", hardness 15, milky white type) manufactured by Exseal Co., Ltd. and a curing agent (10% by mass of aromatic diisocyanate and 90% by mass of plasticizer, based on the total amount of curing agent) were mixed in a ratio of 3:1 and stirred to prepare elastic layer-forming composition a3. The viscosity of the prepared elastic layer-forming composition a3 was 1800 mPa s.

(Elastic layer-forming composition a4)
The main component and curing agent of the silicone resin "Ecoflex 00-20" manufactured by Smooth-On Corp. were mixed and stirred in a ratio of 1:1 to prepare an elastic layer-forming composition a4. The viscosity of the prepared elastic layer-forming composition a4 was 3000 mPa s.

<Preparation of Elastic Layer 10>
The prepared elastic layer-forming compositions a1 to a4 were cast onto a release film "Clean Sepa HY-S10" (a PET film with a release-treated surface, manufactured by Higashiyama Film Co., Ltd., thickness 50 μm) folded into a box shape with the release surface facing inward, so that the thickness after curing would be 4 mm, and after being left to stand at room temperature (25°C) for 7 days, the compositions were removed from the release film to produce sheet-like elastic layers A1 to A4.

The shear storage modulus, tensile breaking strength, tensile breaking elongation, and Young's modulus of the obtained elastic layers A1 to A4 were measured. The measurement results are shown in Table 1. The measurement methods will be explained in detail later.

<Preparation of Composition for Forming Epidermal Layer>
(Composition b1 for forming epidermal layer)
A surface skin layer-forming composition b1 was prepared by adding 5.7 g of butyl acetate to 20 g of an acrylic pressure-sensitive adhesive "SK Dyne 1717" (solid content concentration 45%) manufactured by Soken Chemical & Engineering Co., Ltd., and mixing and stirring with 0.4 g of an aluminum chelate crosslinking agent "M-5A" (solid content concentration 100%) manufactured by Soken Chemical & Engineering Co., Ltd. The solid content concentration of the prepared surface skin layer-forming composition b1 was 35 mass %, and the viscosity was 1500 mPa s.

(Composition b2 for forming epidermal layer)
Elastic layer-forming composition b2 was prepared by dissolving 9 g of Kuraray Co., Ltd.'s acrylic elastomer "CLARITY LA3320" (an A-B-A block copolymer using methyl methacrylate for the hard block and acrylate for the soft block, pellet-like solid) in 16.7 g of a 1:1 mixed solvent of ethyl acetate and butyl acetate. The prepared elastic layer-forming composition b2 had a solids concentration of 35 mass % and a viscosity of 1000 mPa s.

(Composition b3 for forming epidermal layer)
14 g of normal heptane was added to 20 g of "DOWSIL SD 4560 PSA" (addition-type silicone adhesive, solids concentration 60% by mass) manufactured by Dow-Toray Industries, Inc., and 0.18 g of "DOWSIL NC-25 Catalyst" (platinum catalyst, solids concentration xx% by mass) manufactured by Dow-Toray Industries, Inc. was mixed and stirred to prepare a surface layer-forming composition b3. The solids concentration of the prepared surface layer-forming composition b3 was 35% by mass, and the viscosity was 5000 mPa s.

<Preparation of Epidermal Layer 20>
Each of the skin layer-forming compositions b1 to b3 was applied to the release surface of a release film "Clean Sepa HY-S20" (a PET film with a release-treated surface, manufactured by Higashiyama Film Co., Ltd., thickness 50 μm) using a Baker applicator so that the thickness after drying would be 35 μm, and the applied composition was heat-treated at 80°C for 5 minutes using a thermostatic oven, followed by aging at room temperature (25°C) for 24 hours. This produced skin layers B1 to B3.

The shear storage modulus, tensile strength at break, tensile elongation at break, Young's modulus, water contact angle, and adhesive strength to an acrylic plate were measured for the obtained skin layers B1 to B3. The measurement results are shown in Table 2. These measurement methods will be explained in detail later.

<Preparation of artificial skin 1>
The surface of epidermal layer 20 (epidermal layers B1 to B3) opposite the release film was attached to elastic layer 10 (elastic layers A1 to A4) using a hand roller, and the release film was peeled off from epidermal layer 20. Next, particles were sprinkled on epidermal layer 20, and any particles not adhering to the surface of epidermal layer 20 were brushed off and then the surface of epidermal layer 20 was rinsed with running water to produce artificial skin 1 of Examples 1 to 7 and Comparative Examples 1 to 6.

The particles used to produce the artificial skin 1 are as follows. The properties of each particle are shown in Table 3. Note that particles C1 to C5 correspond to the spherical particles 30 in the above-described embodiment.
Particle C1: Sekisui Plastics Co., Ltd. "Techpolymer MBX-5", cross-linked polymethyl methacrylate particles, spherical, average particle diameter 5 μm
Particle C2: Sekisui Plastics Co., Ltd. "Techpolymer MBX-20", cross-linked polymethyl methacrylate particles, spherical, average particle diameter 20 μm
・Particle C3: "Techpolymer SBX-4" manufactured by Sekisui Plastics Co., Ltd., crosslinked polystyrene particles, spherical, average particle diameter 4 μm
Particle C4: "Art Pearl C-600T" manufactured by Negami Chemical Industrial Co., Ltd., cross-linked urethane particles, spherical, average particle diameter 10 μm
Particle C5: "Tospearl 2000B" manufactured by Momentive, silicone particles, spherical, average particle diameter 6 μm
Particle C6: Johnson & Johnson "Johnson Baby Powder", talc, irregular shape, average particle size 11 μm

<Evaluation method>
The obtained elastic layers A1 to A4, epidermal layers B1 to B3, and artificial skin 1 prepared using these were evaluated by the following methods.
(1) Thickness of Elastic Layer 10 and Skin Layer 20 The thickness of the elastic layer 10 and the skin layer 20 was measured using a thickness measuring instrument "TH-104" manufactured by Tester Sangyo Co., Ltd.

(2) Measurement of Tensile Break Strength, Tensile Break Elongation, and Young's Modulus of Elastic Layer 10 and Skin Layer 20 Skin layers B1-B3 were laminated using a hand roller to a thickness of 0.5 μm after peeling the release film from the skin layer. Skin layers B1-B3 and elastic layers A1-A4 were then cut into 10 mm x 70 mm rectangular specimens to prepare test pieces. The resulting specimens were stretched to break using a precision universal testing machine (Shimadzu Corporation, AUTOGRAPH (registered trademark) AGX) at 23°C and 50% humidity, with a gripping distance of 30 mm and a pulling rate of 10 mm/min, to measure the tensile break strength and tensile break elongation. The Young's modulus was also determined from the slope of the linear portion of the resulting strain-stress curve at the initial stage of elongation.

(3) Measurement of Storage Modulus of Elastic Layer 10 and Skin Layer 20 Skin layers B1 to B3 were prepared by peeling the release film from the skin layers B1 to B3 and laminating them using a hand roller to a thickness of 0.5 μm. The skin layers B1 to B3 and the elastic layers A1 to A4 were then cut into 15 mm x 15 mm pieces to prepare test specimens. The shear storage modulus of the resulting test specimens was measured using a viscoelasticity measuring device (TA Instrument, Discovery HR-2) under an environment of 23°C and 50% humidity, in shear mode, with a geometry of 8 mm diameter parallel plates, a frequency of 1 Hz, and a strain of 1%.

(4) Evaluation of Wettability of Epidermal Layer 20 The release films were peeled off from the epidermal layers B1 to B3, and 4 μL of pure water was dropped onto the surface of the antireflection film using a contact angle meter (DropMaster DMo-502, manufactured by Kyowa Interface Science Co., Ltd.) to measure the contact angle of water.
If the water contact angle is 100° or less, it can be said that the artificial skin has sufficient adhesion to cosmetics and paints.

(5) Measurement of Adhesion of Epoxy Layer 20 A corona-treated polyethylene terephthalate (PET) film (Toyobo Ester (registered trademark) Film E5100, manufactured by Toyobo, 50 μm thick) was attached to the surface of each of the epidermal layers B1 to B3 opposite the release film, and the resulting film was cut into a size of 25 mm wide and 100 mm long to prepare a test specimen. The adhesive strength of this substrate-attached test specimen to an acrylic plate as an adherend was measured in accordance with the method described in JIS Z 0237 (2009).
Specifically, the release sheets were peeled off from the skin layers B1 to B3, and the surfaces of the skin layers B1 to B3 opposite the substrate were pressed against an acrylic plate (Acrylite (registered trademark) L: manufactured by Mitsubishi Chemical, thickness 2 mm) by rolling a 2 kg roller back and forth twice. Next, the adhesive strength of the skin layers B1 to B3 was measured using a precision universal testing machine "AUTOGRAPH (registered trademark) AGS-1kNX, 50 N load cell" manufactured by Shimadzu Corporation at a peel speed of 5 mm/s and a peel angle of 180°.

(6) Evaluation of Adhesion Between Elastic Layer 10 and Epidermal Layer 20 The artificial skin 1 obtained in Examples 1 to 11 and Comparative Examples 1 to 3, 5, and 6 was cut into a 10 mm x 50 mm rectangle, and the process of manually stretching it to three times its original size and then returning it to its original size was repeated 20 times. The artificial skin 1 was then visually observed to evaluate the adhesion between the elastic layer 10 and the epidermal layer 20.
The evaluation was carried out according to the following criteria.
A: No lifting or peeling is observed between the elastic layer and the surface layer.
C: Within 20 stretching operations, lifting or peeling was observed between the elastic layer and the surface layer.

(7) Evaluation of the tactile sensation of artificial skin 1 The surface of the artificial skin 1 obtained in Examples 1 to 11 and Comparative Examples 1 to 6 (the surface on which the particles were adhered) was rubbed strongly with a finger 10 times, and the tactile sensation was evaluated. The evaluation was performed according to the following criteria.
(7-1) Evaluation of roughness A: Smooth and pleasant to the touch.
C: Roughness is felt and the feel is bad.
(7-2) Evaluation of Stickiness A: No stickiness is felt and the texture is good.
B: When pressed firmly, it feels slightly sticky, but this does not pose any problems in practical use.
C: Stickiness was felt, and particles, additives, etc. were found to adhere to the hands.
(7-3) Evaluation of stickiness after one month of storage After storing the artificial skin 1 evaluated in (7-2) for one month at room temperature (23°C), the surface (the surface on which the particles were adhered) was rubbed strongly with a finger 10 times to evaluate the tactile sensation. The evaluation was performed according to the same criteria as in (7-2).

<Evaluation results>
Next, the evaluation results of the artificial skin 1 of Examples 1 to 11 and Comparative Examples 1 to 6 are shown in Tables 4 and 5.

As shown in Tables 4 and 5, the artificial skin 1 of Examples 1 to 11, which includes an elastic layer 10 made of an elastic material with a silicone content of 20% by mass or less relative to the total solid content of the elastic layer 10, an epidermal layer 20 made of an acrylic resin laminated on the elastic layer 10, and spherical particles 30 attached to the surface of the epidermal layer 20, achieved favorable results in evaluations of adhesion between the elastic layer 10 and the epidermal layer 20 and tactile feel (roughness, stickiness, stickiness after one month). This confirmed that it is possible to achieve artificial skin 1 that is less sticky and has high toughness against external stress.

In contrast, in the artificial skin 1 of Comparative Example 1, in which amorphous particles C6 made of talc were attached to the surface of the epidermis layer 20, the surface felt rough in the tactile evaluation, and the tactile sensation was poor. Furthermore, when the surface of the epidermis layer 20 was rinsed with water during the manufacturing process, it was confirmed that the particles fell off.
Furthermore, in the artificial skin 1 of Comparative Example 2 in which no particles were attached to the surface of the epidermal layer 20, the surface felt sticky in the evaluation of the feel, and the feel was not good.
Furthermore, in the artificial skin 1 of Comparative Example 3, in which the epidermis layer 20 contained silicone, lifting and peeling were observed between the elastic layer 10 and the epidermis layer 20 in the adhesion evaluation, and the adhesion between the elastic layer 10 and the epidermis layer 20 was poor.
Furthermore, in the artificial skin 1 of Comparative Example 4, which did not have an epidermal layer 20, the spherical particles 30 could not be retained on the surface of the artificial skin 1 (elastic layer 10), and the surface felt sticky in the tactile evaluation, resulting in an unfavorable tactile feel.

Furthermore, in the artificial skin 1 of Comparative Example 5, in which the silicone content in the elastic layer 10 exceeded 20 mass percent relative to the total solid content of the elastic layer 10, lifting and peeling were observed between the elastic layer 10 and the epidermis layer 20 in the evaluation of adhesion, and the adhesion between the elastic layer 10 and the epidermis layer 20 was poor. Furthermore, components of the elastic layer 10 bled out onto the surface of the artificial skin 1, and in the evaluation of stickiness after storage for one month, the surface felt sticky and the feel was poor.
Furthermore, in the artificial skin 1 of Comparative Example 6, in which the content of silicone in the elastic layer 10 exceeded 20% by mass relative to the total solid content of the elastic layer 10 and the epidermis layer 20 contained silicone, lifting and peeling were observed between the elastic layer 10 and the epidermis layer 20, and the adhesion between the elastic layer 10 and the epidermis layer 20 was poor. In addition, the components of the elastic layer 10 bled out onto the surface of the artificial skin 1, and in an evaluation of stickiness after storage for one month, the surface felt sticky and the feel was poor.

Furthermore, when comparing the artificial skins 1 of Examples 1 to 6, which used an elastic layer A1 made of urethane elastomer and an epidermal layer B1 among Examples 1 to 11, it was confirmed that the artificial skins 1 of Examples 1 and 3, which had an elastic layer 10 thickness of 35 μm and used particles C1 and C2 made of crosslinked polymethyl methacrylate particles as the spherical particles 30, obtained particularly good results in the evaluations of adhesion and tactile feel.
Furthermore, among Examples 1 to 11, it was confirmed that the artificial skin 1 of Examples 7 to 9, which used an elastic layer A1 made of urethane elastomer and an epidermal layer B2, all achieved particularly good results in the evaluations of adhesion and tactile feel.
Furthermore, when comparing Examples 2, 8, and 9 in which the thickness of the epidermal layer 20 was 250 μm, it was confirmed that the artificial skin 1 of Examples 8 and 9, which used an epidermal layer B2 that was harder (having a higher Young's modulus) than the epidermal layer B1, obtained better results in the evaluation of stickiness than Example 2. This is presumably because in Examples 8 and 9, the spherical particles 30 were less likely to be embedded in the epidermal layer 20 than in Example 2.

DESCRIPTION OF SYMBOLS 1... Artificial skin, 10... Elastic layer, 20... Epidermal layer, 30... Spherical particle

Claims (10)

an elastic layer made of an elastic material having a silicone content of 20% by mass or less based on the total solid content of the elastic layer;
a surface layer made of an acrylic resin and laminated on the elastic layer;
spherical particles attached to a surface of the skin layer opposite to the elastic layer ,
The spherical particles have an average particle diameter of 1 μm or more and 30 μm or less . The artificial skin described in claim 1, characterized in that the elastic layer contains a urethane-based elastomer. The artificial skin described in claim 1, characterized in that the elastic layer contains an acrylic elastomer. The artificial skin described in any one of claims 1 to 3, characterized in that the elastic layer does not contain a plasticizer. the elastic layer contains a colorant;
The artificial skin of claim 1 , wherein the epidermal layer and the spherical particles do not contain a colorant. The artificial skin described in claim 1, characterized in that the contact angle of water on the surface of the epidermal layer is 100° or less. The artificial skin described in claim 1, characterized in that the spherical particles have an average particle diameter of 10% or more and 50% or less of the thickness of the epidermal layer. The artificial skin described in claim 1, characterized in that the spherical particles are made of resin. a step of curing a solution containing an acrylic resin to form an adhesive surface layer;
forming an elastic layer on the surface layer, the elastic layer being made of an elastic material having a silicone content of 20% by mass or less based on the total solid content of the elastic layer;
A method for manufacturing artificial skin, comprising a step of attaching spherical particles having an average particle diameter of 1 μm or more and 30 μm or less to the surface of the epidermis layer opposite the elastic layer. an elastic layer made of an elastic material having a silicone content of 20% by mass or less based on the total solid content of the elastic layer;
a surface layer made of an acrylic resin and laminated on the elastic layer;
spherical particles attached to the surface of the skin layer opposite to the elastic layer;
Equipped with
The spherical particles have an average particle diameter of 10% to 50% of the thickness of the epidermal layer.