阅读说明：本技术 真皮制品 (Leather products ) 是由 松田兴吉 于 2020-02-03 设计创作，主要内容包括：本发明为真皮制品。提供一种具有真皮特有的触感、手感和耐磨耗性的真皮制品。一种真皮制品,其具备真皮基材和层叠在上述真皮基材上的整饰层,上述整饰层具备由组合物形成的最外层,所述组合物包含丙烯酸类树脂和/或氨基甲酸酯树脂、硅橡胶和交联剂,上述真皮制品的正面的平均摩擦系数(MIU)为0.12～0.30的范围。(The present invention is a genuine leather product. A genuine leather product having touch, hand and abrasion resistance peculiar to genuine leather is provided. A genuine leather product, it has genuine leather substrate and laminates the decorative layer on the above-mentioned genuine leather substrate, the above-mentioned decorative layer has outermost layer formed by composite, said composite comprises acrylic resin and/or urethane resin, silicone rubber and cross-linking agent, the mean coefficient of friction (MIU) of the obverse of the above-mentioned genuine leather product is in the range of 0.12-0.30.)

1. A genuine leather product, which comprises a genuine leather substrate and a finishing layer laminated on the genuine leather substrate,

the finishing layer comprises an outermost layer formed by a composition, wherein the composition comprises an acrylic resin and/or a urethane resin, a silicone rubber and a cross-linking agent, and the average friction coefficient MIU of the front surface of the genuine leather product is in the range of 0.12-0.30.

2. The dermal product of claim 1, wherein the quotient MIU/MMD of the frontal average coefficient of friction MIU and the change in average coefficient of friction MMD is 25 or more.

3. The dermal article according to claim 1 or 2, wherein a product of a mean deviation SMD of the front surface roughness and a change MMD of the mean friction coefficient, smdxmd, is 0.015 or less.

4. The dermal product according to any one of claims 1 to 3, wherein the finishing layer includes a primer layer formed on the surface of the dermal base material, and the outermost layer laminated on the primer layer.

5. The dermal product according to any one of claims 1 to 4, wherein a mass ratio of the acrylic resin to the urethane resin constituting the outermost layer is 1: 0.2-1: 1.

6. the dermal product of any one of claims 1 to 5, wherein a mass ratio of the resin to the silicone rubber constituting the outermost layer is 1: 0.3-1: 2.2.

7. the dermal product of any one of claims 1 to 6, wherein the acrylic resin comprises a fluorine-modified acrylic resin.

8. The dermal product of any one of claims 1 to 7, wherein the silicone rubber is a silicone emulsion capable of forming a rubber elastic coating film by drying.

9. The dermal product of any one of claims 1 to 8, wherein the dermal substrate is an unground dermis.

10. The dermal product of any one of claims 1 to 9, wherein the thickness of the finishing layer is 1 to 30 μm.

Technical Field

The present invention relates to a dermal article.

Background

Genuine leather products are used in various fields such as clothing, bags, shoes, interior materials, and vehicle interior materials due to unique texture and high-grade texture such as appearance (gloss, texture, etc.), hand, touch (softness, elasticity, swelling, smoothness, etc.).

The surface finishing method of genuine leather is various depending on the use of raw material leather and leather products. In addition to sueded leather and unfinished leather such as sueded leather and nubuck leather, the surface of a genuine leather substrate is usually finished by coating. The coating was repeated a plurality of times to form a coating film (resin coating film) on the genuine leather.

There are leather products called unfinished leather obtained by finishing a leather base material without providing a resin coating (hereinafter, sometimes referred to as a "finishing layer") after tanning, that is, while retaining the texture peculiar to leather. However, the unfinished leather has a problem of poor durability, particularly abrasion resistance, although it has good hand and touch.

In order to improve the durability of the raw leather, a resin coating (finishing layer) is formed on the surface of the genuine leather base material as described above. For example, patent document 1 discloses a genuine leather material in which a lining layer (lining layer) and a coating layer having a specific thickness are laminated on a base layer made of double-layered leather, and an automobile interior using the same. However, the following problems are present: since the coating film is formed using a hard resin, the texture, particularly the texture and touch, peculiar to the real leather are impaired.

Disclosure of Invention

Problems to be solved by the invention

The present invention has been made in view of such a situation, and an object thereof is to provide a genuine leather product having a touch, texture and abrasion resistance peculiar to genuine leather.

Means for solving the problems

The genuine leather product of the embodiment of the invention comprises a genuine leather substrate and a finishing layer laminated on the genuine leather substrate. The finishing layer has an outermost layer formed of a composition containing an acrylic resin and/or a urethane resin, a silicone rubber, and a crosslinking agent. The average friction coefficient (MIU) of the front surface of the genuine leather product is in the range of 0.12-0.30.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the embodiments of the present invention, a genuine leather product having a touch, a hand and abrasion resistance peculiar to genuine leather can be provided.

Drawings

Fig. 1 is a schematic cross-sectional view of one embodiment of a dermal article.

Description of the reference numerals

1 … dermis product, 2 … dermis base material, 3 … finishing layer, 31 … bottom coating layer, 32 … outermost layer

Detailed Description

The genuine leather product of the present embodiment is the following genuine leather product: the top layer of the top layer is formed from a composition (hereinafter, sometimes referred to as "top layer resin composition") containing an acrylic resin and/or a urethane resin, a silicone rubber, and a crosslinking agent. The average friction coefficient (MIU) of the front surface of the genuine leather product is in the range of 0.12-0.30.

Fig. 1 is a diagram schematically showing a sectional structure of a genuine leather product 1 according to an embodiment. In the genuine leather product 1, the finishing layer 3 includes the primer layer 31 and the outermost layer 32, and the outermost layer 32 is sequentially laminated on the genuine leather base 2 via the primer layer 31.

In the present embodiment, the dermal base material is not particularly limited, and examples of the raw material include those derived from mammals such as cows, horses, pigs, goats, sheep, deer, and kangaroos, birds such as ostriches, and reptiles such as turtles, exendins, pythons, and crocodiles. Among them, cowhide having high versatility and large area is preferable. The raw hide itself, dried or salt-pickled and preserved hide is referred to as raw hide, and the raw hide is subjected to a tanning process.

A substance that tannes the skin (hide) of an animal to impart durability (heat resistance, putrefaction resistance, chemical resistance, etc.) and exhibits a leather-like feel is called "dermis" (also simply referred to as "leather") to be distinguished from an untanned "skin".

The tanning process is generally roughly divided into a tanning process, a dyeing process and a finishing process, and is further divided into the following steps.

Tanning process: raw leather, soaking, splitting, fleshing, unhairing, liming, splitting, reliming, deliming, softening with enzyme, pickling and tanning.

A dyeing procedure: wringing, screening, shaving, retanning, dyeing and fatliquoring, setting out, drying, rewetting, staking (rubbing, knocking), drying on a veneer, and buffing.

A finishing process: coating, back spraying, ironing, die pressing and polishing.

Although the respective steps are improved, the steps are technically almost fixed and are well known in the art. Of course, the sequence may be partially changed, omitted, performed a plurality of times, or replaced with another step.

Before coating, buffing is usually carried out. Buffing is a process for smoothing the surface by shaving off the surface of the grain surface, and homogenizing the surface by removing factors affecting the appearance quality such as individual differences, site differences, moth eating, scratching, skin scars, and the like. In the present embodiment, it is preferable that the buffing is not performed as long as the above-described defects (factors affecting the appearance quality) are not so large in order to exhibit the original design and touch of the animal leather.

In the present embodiment, a real leather that has been subjected to plate drying or buffing may be used as the real leather base material. In the present specification, the coated genuine leather is referred to as a "genuine leather product" with respect to the genuine leather substrate.

The genuine leather product of the present embodiment is obtained by laminating a finishing layer on the surface of the genuine leather base material.

The finishing layer is a resin layer formed on the genuine leather substrate, and is not limited to a 1-layer structure, and may be 2 or 3 or more layers. The finishing layer has at least an outermost layer, and in the case of a 1-layer structure, the finishing layer comprises only the outermost layer. Here, the outermost layer refers to the layer located outermost, and is the layer forming the front surface of the genuine leather product. The front side of the dermal product refers to: the surface (design surface) of the surface and the back surface of the genuine leather product that is visible to the eye in use.

In one embodiment, the finishing layer may include a primer layer formed on the front surface of the dermal base material, and an outermost layer laminated on the primer layer. The primer layer also forms part of the finish layer. Further, a base coat layer, an intermediate coat layer, and the like (hereinafter collectively referred to as "inner layer") may be provided between the undercoat layer and the outermost layer, and in this case, the inner layer also constitutes a part of the finishing layer.

More specifically, the finishing layer as the outermost layer may be directly laminated on the dermal base material, or the outermost layer 32 may be laminated on the dermal base material 2 via the primer layer 31 as shown in fig. 1. Further, the inner layer and the outermost layer may be laminated in this order on the dermal base material with the primer layer interposed therebetween. The wettability of the inner layer or the outermost layer can be improved by interposing the primer layer therebetween, and the adhesion of the inner layer or the outermost layer can be improved. Therefore, the abrasion resistance of the genuine leather product can be improved. Further, the undercoat layer also plays a role of filling pores on the surface of the dermal base material and adjusting the color by adding a colorant, so that unevenness of the inner layer and/or the outermost layer can be eliminated and the appearance can be improved.

In the present embodiment, the outermost layer is formed of a composition containing an acrylic resin and/or a urethane resin, a silicone rubber, and a crosslinking agent. That is, the outermost layer contains at least 1 resin selected from the group consisting of acrylic resins and urethane resins and silicone rubber, and has a crosslinked structure based on a crosslinking agent. This makes it possible to improve the abrasion resistance of the genuine leather product. Further, by including silicone rubber in the outermost layer, the feel and hand of the resulting genuine leather product can be improved. In one embodiment, only the outermost layer of the finishing layer includes silicone rubber.

The acrylic resin constituting the outermost layer is not particularly limited, and examples thereof include acrylic resins selected from alkyl acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, isobutyl acrylate, and 2-ethylhexyl acrylate; alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, isobutyl methacrylate, and 2-ethylhexyl methacrylate; hydroxyl group-containing acrylates such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and 4-hydroxybutyl acrylate; polymers of at least 1 monomer selected from the group consisting of acrylic acid, methacrylic acid and derivatives thereof, such as hydroxyl group-containing methacrylates such as 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate and 4-hydroxybutyl methacrylate, and modified products thereof. These monomers may be used alone in 1 kind or in combination of two or more kinds. Among these, from the viewpoint of abrasion resistance and water resistance, the acrylic resin is preferably a fluorine-modified acrylic resin, that is, a fluorine-modified acrylic resin. As the acrylic resin, commercially available products can be used, and an emulsion type is preferably used from the viewpoint of environmental load.

The amount of the acrylic resin to be blended in the resin composition for the outermost layer is not particularly limited, and is preferably 50% by mass or less, more preferably 15 to 40% by mass, and may be 15 to 25% by mass in terms of nonvolatile matter. That is, the content of the acrylic resin in the outermost layer is preferably 50% by mass or less. By setting the amount of the acrylic resin to 50% by mass or less, the coating film feel can be suppressed from becoming strong and the hand is not easily rough or hard. In the present specification, "nonvolatile components" mean: the ratio of the residual component to the original mass when sample 10g was heated at 120. + -. 10 ℃ for 3 hours to evaporate.

The urethane resin constituting the outermost layer is not particularly limited, and examples thereof include various polyurethanes such as polycarbonate-based polyurethane resin, polyether-based polyurethane resin, and polyester-based polyurethane resin. These may be used alone in 1 kind or in combination of two or more kinds. Among these, polycarbonate-based polyurethane resins are preferred from the viewpoint of abrasion resistance, polyether-based polyurethane resins are preferred from the viewpoint of touch and texture, and a combination of these is more preferred. The urethane resin may be a commercially available product, and is preferably a one-pack emulsion type in view of environmental load.

The amount of the urethane resin to be blended in the resin composition for the outermost layer is not particularly limited, and is preferably 50% by mass or less, more preferably 3 to 40% by mass, even more preferably 5 to 25% by mass, and may be 10 to 20% by mass, in terms of nonvolatile matter. That is, the content of the urethane resin in the outermost layer is preferably 50% by mass or less. By setting the amount of the urethane resin to 50% by mass or less, the coating film feel can be suppressed from becoming strong and the hand is not easily rough or hard. Further, by setting the amount of the urethane resin to 3% by mass or more, the film formability is good and the wear resistance can be improved.

In the present embodiment, as the resin constituting the outermost layer, an acrylic resin and a urethane resin may be used alone or in combination. From the viewpoint of texture, an acrylic resin is preferable, and from the viewpoint of abrasion resistance, a urethane resin is preferably used.

When the acrylic resin and the urethane resin are used in combination, the total amount of the acrylic resin and the urethane resin in the outermost resin composition is not particularly limited, but is preferably 17 to 90% by mass, more preferably 30 to 70% by mass, and may be 30 to 50% by mass in terms of nonvolatile components. That is, the total content of the acrylic resin and the urethane resin in the outermost layer is preferably 17 to 90% by mass. When the total amount is 17% by mass or more, the film formability is good and the wear resistance can be improved. When the amount is 90% by mass or less, the coating feel is suppressed from becoming strong and the hand is hardly coarsened and hardened.

The mass ratio (nonvolatile content) of the acrylic resin to the urethane resin is not particularly limited, and is preferably 1: 0.2-1: 1, more preferably 1: 0.5-1: 0.9. by setting the mass ratio of the urethane resin to the acrylic resin to 0.2 or more, the abrasion resistance can be improved, and by setting the mass ratio to 1 or less, the coating feel can be suppressed from becoming strong, the thickness of the finish layer becomes thick, and the texture is not easily made hard.

The resin constituting the outermost layer is mainly composed of an acrylic resin and/or a urethane resin, but may contain other resin components within a range not impairing the effects of the present invention. Examples of the other Resin component include an epoxy Resin and a silicone Resin (Resin).

In the present embodiment, the silicone rubber used in the outermost layer is silicone having rubber elasticity at normal temperature (22 ℃), and is distinguished from silicone oil and silicone resin. The silicone rubber is a rubber having a siloxane bond in the main chain, and more specifically, a silicone having a linear structure molecule having a repetition number of the siloxane bond of 5000 to 10000 and capable of forming a rubber elastic coating film is exemplified.

The rubber elasticity of silicone rubber can be evaluated by the elastic modulus of a coating film formed of the silicone rubber (a rubber elasticity coating film of silicone rubber only). The elastic modulus of the rubber elastic coating is, for example, preferably 0.001 to 0.5MPa, more preferably 0.001 to 0.2MPa, still more preferably 0.01 to 0.1MPa, and may be 0.03 to 0.08 MPa.

The elastic modulus of the rubber elastic coating IS calculated by coating a silicone rubber solution such as a silicone emulsion on flat release paper (EV130TPD, manufactured by linetec) with an applicator so that the thickness after drying IS 30 to 100 μm, and then performing a heat treatment at 80 ℃ for 10 minutes and 130 ℃ for 5 minutes to prepare a rubber elastic coating, collecting a test piece having a length of 150mm and a width of 30mm from the rubber elastic coating, mounting the test piece on a jig of a tensile tester (AUTOGRAPH AG-IS type, manufactured by shimadzu corporation) at a room temperature of 22 ± 2 ℃ and a relative humidity of 65 ± 5% RH at a holding width of 30mm and a holding interval of 50mm, and stretching the test piece at a stretching speed of 200 mm/minute, and dividing the elongation (mm) of the test piece by the value of the holding interval (mm) (elongation (mm)/50mm) × 100) as an X axis, and dividing the stress of the test piece (N) by a cross-sectional area (stress) of the test piece (mm) obtained by dividing the holding interval (mm) as an X axis²) The value obtained (stress (N)/cross-sectional area (mm)²) Plotted as the Y-axis. From the resulting plot, the X-axis is calculated: the slope of the regression line with an elongation of 0.05 to 10% is used as the elastic modulus of the rubber elastic coating.

Specific examples of the silicone rubber include dimethyl silicone rubber, rubbers containing modified products of dimethyl polysiloxane (e.g., vinyl methyl silicone rubber, phenyl vinyl methyl silicone rubber, fluorosilicone rubber, etc.), silicone rubber-acrylic copolymers, silicone rubber-urethane copolymers, and the like. These may be used alone in 1 kind or in combination of two or more kinds. Among them, from the viewpoint of general versatility, at least 1 selected from the group consisting of dimethyl silicone rubber, vinyl methyl silicone rubber, phenyl vinyl methyl silicone rubber, and fluorosilicone rubber is preferable, and dimethyl silicone rubber is more preferable. In one embodiment, the silicone rubber to be blended in the resin composition for the outermost layer is preferably a silicone emulsion capable of forming a rubber elastic coating film by drying. That is, the silicone rubber constituting the outermost layer is preferably formed of a silicone emulsion capable of forming a rubber elastic coating by drying, and may be formed of a self-crosslinking silicone emulsion. The silicone rubber may be a commercially available one, and an aqueous emulsion type is preferably used because of ease of mixing with the urethane resin.

The amount of silicone rubber added to the resin composition for the outermost layer is not particularly limited, and is preferably 15 to 70% by mass, more preferably 30 to 60% by mass, and may be 35 to 50% by mass, in terms of nonvolatile matter. That is, the content of the silicone rubber in the outermost layer is preferably 15 to 70 mass%. By setting the amount of silicone rubber to 15% by mass or more, the coating film feel can be suppressed from becoming strong, the hand feel is not easily coarsened and hardened, and the touch feel can be improved. By setting the amount to 70% by mass or less, the touch and design properties are easily maintained.

The mass ratio (nonvolatile content) of the resin constituting the outermost layer (preferably the total amount of the acrylic resin and the urethane resin) to the silicone rubber is not particularly limited, and is preferably 1: 0.3-1: 2.2, more preferably 1: 0.5-1: 1.7, can be 1: 0.8-1: 1.3. by setting the mass ratio of the silicone rubber to the resin to 0.3 or more, the feel and hand of the obtained genuine leather product can be improved. In addition, when the amount is 2.2 or less, the resulting genuine leather product can be prevented from being excessively polished, and the design can be improved.

Examples of the crosslinking agent used for the outermost layer include carbodiimide-based crosslinking agents, aziridine-based crosslinking agents, and isocyanate-based crosslinking agents. These may be used alone in 1 kind or in combination of two or more kinds. Among them, isocyanate-based crosslinking agents are preferable. The crosslinking agent used in the outermost layer may be a commercially available one, and is preferably an emulsion type from the viewpoint of environmental load.

The carbodiimide-based crosslinking agent is not particularly limited, and can be appropriately selected from generally used carbodiimide-based crosslinking agents. Among them, those having 2 or more carbodiimide groups are preferable, and examples thereof include aromatic polycarbodiimides such as poly (4, 4' -diphenylmethane carbodiimide), poly (p-phenylene carbodiimide), poly (m-phenylene carbodiimide), poly (diisopropylphenyl carbodiimide), and poly (triisopropylphenyl carbodiimide); alicyclic polycarbodiimides such as poly (dicyclohexylmethane carbodiimide); and aliphatic polycarbodiimides such as poly (diisopropylcarbodiimide). These carbodiimide-based crosslinking agents may be used alone in 1 kind or in combination of two or more kinds.

The carbodiimide group of the carbodiimide-based crosslinking agent reacts with the carboxyl group of the resin used in the outermost layer to form an N-acylurea, thereby forming a three-dimensional crosslinked structure. This improves the adhesion between the dermal base material, the primer layer, or the inner layer and the outermost layer, and the film formation property of the outermost layer, and improves the abrasion resistance of the dermal product.

The blending amount of the carbodiimide-based crosslinking agent in the resin composition for the outermost layer is not particularly limited, and is preferably 2 to 5% by mass in terms of nonvolatile components. When the amount of the compound is 2% by mass or more, the strength of the coating film can be improved, and the abrasion resistance and the friction fastness can be improved. When the amount is 5% by mass or less, the hardness of the coating film can be prevented, and the texture can be made hard and hard.

The aziridine-based crosslinking agent is not particularly limited, and may be appropriately selected from commonly used aziridine-based crosslinking agents. Examples thereof include diphenylmethane-4, 4' -bis (1-aziridinecarboxamide), trimethylolpropane tri- β -aziridinylpropionate, tetramethylolmethane tri- β -aziridinylpropionate, toluene-2, 4-bis (1-aziridinecarboxamide), triethylenemelamine, bis-isophthaloyl-1- (2-methylaziridine), tri-1- (2-methylaziridine) phosphine, trimethylolpropane tri- β - (2-methylaziridine) propionate and the like. These aziridine-based crosslinking agents may be used alone in 1 kind or in combination of two or more kinds.

The aziridine group of the aziridine-based crosslinking agent reacts with a carboxyl group of the resin used in the outermost layer to form a three-dimensional crosslinked structure. This improves the adhesion between the dermal base material, the primer layer, or the inner layer and the outermost layer, and the film formation property of the outermost layer, and improves the abrasion resistance of the dermal product.

The blending amount of the aziridine-based crosslinking agent in the resin composition for the outermost layer is not particularly limited, and is preferably 1 to 2% by mass in terms of nonvolatile components. When the amount of the compound is 1% by mass or more, the strength of the coating film can be improved, and the abrasion resistance and the friction fastness can be improved. When the amount is 2% by mass or less, the hardness of the coating film can be prevented, and the texture can be made hard and hard.

The isocyanate-based crosslinking agent is not particularly limited, and can be appropriately selected from among isocyanate-based crosslinking agents generally used. Examples thereof include aromatic diisocyanates such as phenylene diisocyanate, Toluene Diisocyanate (TDI), 4 '-diphenylmethane diisocyanate (MDI), 2, 4' -diphenylmethane diisocyanate, naphthalene diisocyanate, and xylylene diisocyanate; aliphatic diisocyanates and alicyclic diisocyanates such as Hexamethylene Diisocyanate (HDI), lysine diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate (IPDI), dicyclohexylmethane diisocyanate, and tetramethylxylylene diisocyanate. These isocyanate-based crosslinking agents may be used alone in 1 kind or in combination of two or more kinds.

The isocyanate-based crosslinking agent reacts with active hydrogen and the like present in the resin component used in the outermost layer to form a crosslinked structure. This improves the film-forming property of the outermost layer, and improves the abrasion resistance of the genuine leather product.

The amount of the isocyanate-based crosslinking agent to be blended in the resin composition for the outermost layer is not particularly limited, and is preferably 3 to 20% by mass, more preferably 8 to 20% by mass, and may be 10 to 18% by mass in terms of nonvolatile matter. When the amount of the compound is 3% by mass or more, the strength of the coating film can be improved, and the abrasion resistance and the friction fastness can be improved. When the amount is 20% by mass or less, the hardness of the coating film can be prevented, and the texture can be made hard and rough.

The resin composition for the outermost layer (i.e., the resin liquid forming the outermost layer) may contain, as necessary, various additives such as a colorant (pigment, dye), a matting agent, a smoothing agent, a surfactant, a filler, a leveling agent, and a thickener within a range not impairing the effects of the present invention. These may be used alone or in combination of 1. In addition to these additives, a solvent such as a highly polar solvent may be contained as necessary. As the solvent, water is preferably used from the viewpoint of environmental load.

In one embodiment, a silicone oil may be used as the smoothing agent. The silicone oil is a liquid silicone at room temperature, and specifically includes dimethylsilicone oil having a repeating number of siloxane bonds of less than 5000.

The outermost layer is formed by applying the resin composition for an outermost layer on the surface of the dermal base, the surface of the primer layer, or the surface of the inner layer, and then performing heat treatment.

In coating the resin composition for the outermost layer, various conventionally known methods can be employed. For example, a reverse roll coater, a spray coater, a roll coater, a gravure coater, a kiss roll coater, a knife coater, a comma coater, or the like can be used without particular limitation. Among them, coating by a reverse roll coater or a spray coater is preferable in that a uniform and thin coating film can be formed at a low coating amount. The coating thickness or the wet coating amount can be appropriately set according to the desired thickness of the finishing layer.

The resin is dried to evaporate the solvent in the resin solution, and heat treatment is performed to promote a crosslinking reaction between the resin and the crosslinking agent to form a coating film having sufficient strength. In order to prevent excessive evaporation of water from the dermal matrix, it is preferable to perform heat treatment so that the dermal matrix itself does not reach a temperature of 80 ℃ or higher. Therefore, the heat treatment temperature is preferably 90 to 130 ℃, and more preferably 100 to 120 ℃. The heat treatment time is preferably 1 to 5 minutes, and more preferably 2 to 3 minutes. By setting the heat treatment temperature and the heat treatment time to be not less than the lower limit values, insufficient drying and crosslinking reaction can be prevented. By setting the heat treatment temperature and the heat treatment time to be not more than the upper limit values, the touch and the touch can be prevented from becoming rough and hard.

Next, the undercoat layer will be described. In one embodiment, the primer layer is a layer including at least a mixed layer in which a resin and fibers of the dermal base material are mixed together, the mixed layer being formed by allowing the primer resin composition to penetrate the surface of the dermal base material. The primer layer may include a resin layer formed only of a resin on the surface of the layer, together with a layer in which the resin and the fibers of the genuine leather substrate are mixed.

The primer layer is formed by applying a resin composition for primer layer to the surface of the dermal substrate and then performing heat treatment. In one embodiment, the resin composition for the primer layer is applied to the surface of the dermal base material and heat-treated, and then the resin composition for the primer layer is applied again and heat-treated. This makes it possible to form a uniform coating film on the undercoat layer.

As the resin constituting the undercoat layer, the same resins as the acrylic resin and the urethane resin described above as the resin constituting the outermost layer can be used. These may be used alone or in combination of 1. Among them, a polycarbonate-based urethane resin is preferably used from the viewpoint of durability. The resin composition may be the same as or different from that of the outermost layer and the undercoat layer, for example. Further, the resin composition for an undercoat layer (i.e., the resin liquid for forming the undercoat layer) may contain, as necessary, other resin components (epoxy resin, silicone resin, etc.) and various additives (coloring agent (pigment, dye), matting agent, smoothing agent, surfactant, filler, leveling agent, thickener, etc.) as in the outermost layer. These may be used alone or in combination of 1. Among them, a colorant is preferably contained, and the colorant is preferably a pigment. This makes it possible to color the base coat layer, thereby reducing color unevenness of the dermal base material. In addition to these additives, a solvent such as a highly polar solvent may be contained as necessary. As the solvent, water is preferably used from the viewpoint of environmental load.

The viscosity of the resin composition for an undercoat layer is preferably low. Specifically, the measurement value is preferably 10 to 20 seconds by using a cup viscometer (viscosity cup NK-2, manufactured by Anest Iwata). When the viscosity is in this range, the resin liquid forming the primer layer easily penetrates the grain surface, and thus a layer in which the resin and the fibers of the genuine leather substrate are mixed can be formed as described above.

When the resin composition for an undercoat layer is applied, various methods known in the art can be used. For example, a reverse roll coater, a spray coater, a roll coater, a gravure coater, a kiss roll coater, a knife coater, a comma coater, or the like can be used without particular limitation. Among them, coating by a reverse roll coater or a spray coater is preferable in that a uniform and thin coating film can be formed at a low coating amount. The coating thickness or the wet coating amount can be appropriately set according to the desired thickness of the finishing layer.

The resin is dried to evaporate the solvent in the resin liquid, and heat treatment is performed to promote a crosslinking reaction between the resin and the crosslinking agent when the crosslinking agent is compounded, thereby forming a coating film having sufficient strength. In order to prevent excessive evaporation of water from the dermal matrix, it is preferable to perform heat treatment so that the dermal matrix itself does not reach a temperature of 80 ℃ or higher. Therefore, the heat treatment temperature is preferably 90 to 130 ℃, and more preferably 100 to 120 ℃. The heat treatment time is preferably 1 to 5 minutes, and more preferably 2 to 3 minutes. By setting the heat treatment temperature and the heat treatment time to be not less than the lower limit values, insufficient drying and crosslinking reaction can be prevented. By setting the heat treatment temperature and the heat treatment time to be not more than the upper limit values, the touch and the touch can be prevented from becoming rough and hard.

When the inner layer is provided as a part of the finishing layer, the same resin as the acrylic resin or urethane resin used for the outermost layer can be used as the resin constituting the inner layer. These may be used alone or in combination of 1. The resin composition may be the same as or different from that of the outermost layer and the inner layer, for example. Further, the resin composition for the inner layer (i.e., the resin liquid for forming the inner layer) may contain, as necessary, other resin components (epoxy resin, silicone resin, etc.), various additives (coloring agent (pigment, dye), matting agent, smoothing agent, surfactant, filler, leveling agent, thickener, etc.) as in the outermost layer. In addition to these additives, a solvent such as a highly polar solvent may be contained as necessary. As the solvent, water is preferably used from the viewpoint of environmental load.

The thickness of the finishing layer is not particularly limited, but is preferably 1 to 30 μm, more preferably 1 to 20 μm, and further preferably 5 to 10 μm. By setting the thickness to 1 μm or more, the abrasion resistance and the friction fastness can be improved. By setting the thickness to 30 μm or less, the design and touch peculiar to the dermis can be easily maintained. In the case where the finishing layer includes a plurality of resin layers, the thickness of the finishing layer is the sum of the thicknesses of the plurality of resin layers. For example, in the case where the finishing layer is composed of the undercoat layer and the outermost layer, the total of the thickness of the undercoat layer and the thickness of the outermost layer is defined as the thickness of the finishing layer. When the finishing layer is composed of the undercoat layer, the inner layer and the outermost layer, the thickness of the undercoat layer and the sum of the thickness of the inner layer and the thickness of the outermost layer are defined as the thickness of the finishing layer.

The thickness of the outermost layer is not particularly limited, but is preferably 1 to 30 μm, more preferably 1 to 20 μm, and still more preferably 3 to 10 μm. By setting the thickness to 1 μm or more, the abrasion resistance and the friction fastness can be improved. By setting the thickness to 30 μm or less, the design and touch peculiar to the dermis can be improved.

The thickness of the undercoat layer is not particularly limited, but is preferably 1 to 8 μm, and more preferably 1 to 3 μm. By setting the thickness to 1 μm or more, the adhesion and abrasion resistance between the inner layer and the outermost layer can be improved. By setting the thickness to 8 μm or less, the coating feeling can be suppressed from becoming strong, the thickness of the finish layer can be suppressed from becoming thick, and the texture is not easily made thick or hard. As described above, the primer layer includes a portion penetrating into the dermal base material (i.e., a layer in which the resin and the fibers of the dermal base material are mixed), and in the present specification, the thickness of the penetrating portion is not included in the thickness of the primer layer, and the thickness of the resin layer including only the resin is defined as the thickness of the primer layer. Therefore, the thickness of the finishing layer does not include the thickness of the penetration portion, that is, the thickness of the finishing layer refers to the thickness of the resin layer on the dermal base material.

This makes it possible to obtain the dermal product of the present embodiment.

The average friction coefficient (MIU) of the front surface of the genuine leather product of the present embodiment is in the range of 0.12 to 0.30. MIU is an index indicating the degree of sliding of the surface, and sliding is more likely as the value is smaller. When MIU is in this range, the feel and hand of the leather product can be improved. The MIU is preferably 0.15 or more, more preferably 0.17 or more, and further preferably 0.25 or less, more preferably 0.22 or less. The average coefficient of friction (MIU) was determined by measuring the front surface of A leather product using an automated front surface tester (KES-FB4-AUTO-A, KATO TECH).

In the present embodiment, the average friction coefficient (MIU), the change in the average friction coefficient (MMD), and the average deviation in surface roughness (SMD) measured on the front surface of the genuine leather product by the automated surface tester (KES-FB4-AUTO-A, KATO TECH co., ltd) preferably satisfy the following relationships.

The quotient (MIU/MMD) of the average friction coefficient (MIU) and the change in average friction coefficient (MMD) is preferably 25 or more. MMD is an indicator of the smoothness or roughness of a surface, with smaller values indicating smoother. By setting the MIU/MMD in this range, the touch of the genuine leather product can be made to be the wet touch peculiar to the natural leather. The upper limit is not particularly limited, and may be, for example, 65 or less, because the larger the MIU/MMD is, the more wet touch feeling peculiar to natural leather is obtained.

The product (SMD × MMD) of the average deviation of surface roughness (SMD) and the change in average friction coefficient (MMD) is preferably 0.015 or less. SMD is an index of surface unevenness, and a larger value indicates a larger surface unevenness. By setting the SMD × MMD to this range, the feel of the genuine leather product becomes perceived as smooth. The lower limit of SMD × MMD is not particularly limited, and may be, for example, 0.001 or more, and may be 0.010 or more. Here, the unit of the mean deviation (SMD) is μm.

The use of the genuine leather product of the present embodiment is not particularly limited, and the genuine leather product of the present embodiment can be used for various interior material applications for vehicles, including, for example, interior materials for automobiles such as seats for automobiles, ceiling materials, instrument panels, door linings, and steering wheels, and can also be used for interior applications such as a surface of a sofa and a chair, and for other modern applications such as bags and shoes.