JP2025074110A - Synthetic resin skin material - Google Patents

Abstract

[Problem] To provide a synthetic resin skin material with good moldability at room temperature. [Solution] The synthetic resin skin material has a skin layer containing a resin, and the skin layer has a 1 kgf constant load elongation rate in the width direction at 23°C, measured at a load of 1 kgf in accordance with ASTM D 3107 (2019), of 7% to 100%, and a 1 kgf constant load set rate in the width direction at 23°C of 0.5% to 15%. [Selected Figure] Figure 1

Description

This disclosure relates to synthetic resin skin materials.

Synthetic resin skin materials, which have excellent durability, are often used in place of natural leather, fiber sheets, etc. for automobile interior parts such as instrument panels, door trim, seats, and ceilings, railway car and aircraft interior parts such as trim, seats, and ceilings, furniture, shoes, footwear, bags, interior and exterior components for building decoration, clothing coverings and linings, wall coverings, etc.

For example, when a synthetic resin skin material is used instead of natural leather, the outermost surface of the synthetic resin skin material will have a texture similar to that of natural leather, i.e., a grain pattern. In addition, there are cases where a deeper texture pattern is required for the synthetic resin skin material in order to further enhance the design.

Conventionally, when forming a textured pattern on a skin material such as synthetic leather, molding at room temperature, such as compression molding or stamping molding using a pair of dies, is required. In addition, when a synthetic resin skin material is used for the interior of an automobile, for example, parts such as automobile doors have three-dimensional shapes in both the up-down and left-right directions, so it is preferable that the synthetic resin skin material used for the door has a certain degree of stretchability in both the up-down and left-right directions.

When providing a synthetic resin skin with an uneven surface, or when fixing a synthetic resin skin to a substrate having a three-dimensional shape for interior use, hot molding can provide the synthetic resin skin with thermal extensibility. However, there are concerns that hot molding may affect the appearance and texture of the resin used in the synthetic resin skin, or affect the substrate having a three-dimensional shape, so the moldability of the synthetic resin skin at room temperature is important.

However, known synthetic resin skin materials do not have sufficient elasticity, so there is concern that wrinkles, sagging, etc. may occur during molding when compression molding, stamping molding, etc. are performed at room temperature.

As a synthetic leather with good appearance, touch, breathability and mechanical properties, a wet synthetic leather has been proposed in which a surface layer is formed on a pretreated substrate using a wet method, the substrate is peeled off from the formed surface layer, and a base fabric is bonded to the peeled surface with an adhesive (see Patent Document 1).

The wet synthetic leather described in Patent Document 1 can be distributed as a laminate before being attached to a base fabric by pretreating the substrate, and it is described that after being attached to the base fabric, it has good adhesion to the base fabric.

A thermoplastic polymerizable composition has been proposed for obtaining a skin material that has good shape conformability and flexibility at room temperature and is less likely to wrinkle when applied to a substrate (see Patent Document 2).
The thermoplastic polymerizable composition described in Patent Document 2 contains a 4-methyl-1-pentene/α-olefin copolymer and a propylene-based resin having specific physical properties, and is described as being suitable for use as a skin layer in a skin material.

Japanese Patent Application Publication No. 09-031859 JP 2014-214227 A

However, the synthetic resin skin material described in Patent Document 1 uses a wet method and requires special processing equipment, which is not preferable from the viewpoint of productivity. Furthermore, according to the inventor's investigation, the synthetic leathers described in Patent Documents 1 and 2 have good flexibility. However, they are still insufficient in terms of moldability at room temperature and the effect of suppressing the occurrence of wrinkles when subjected to stamping molding at room temperature.

The objective of one embodiment of the present invention is to provide a synthetic resin skin material that has good moldability at room temperature.

The means for solving the problems include the following aspects.
<1> A synthetic resin skin material having a skin layer containing a resin, in which a constant load elongation rate of 1 kgf (9.8 N) in the width direction at 23°C, measured at a load of 1 kgf (9.8 N) in accordance with ASTM D 3107 (2019), is 7% to 100%, and a constant load set rate of 1 kgf (9.8 N) in the width direction at 23°C is 0.5% to 15%.
<2> The synthetic resin skin material according to <1>, wherein the synthetic resin skin material has a 1 kgf constant load elongation rate in the length direction under 23°C conditions, measured at a load of 1 kgf in accordance with ASTM D 3107 (2019), of 7% to 100%, and a 1 kgf constant load set rate in the length direction under 23°C conditions of 0.5% to 15%.
<3> The synthetic resin skin material according to <1> or <2>, wherein the resin includes at least one selected from the group consisting of a urethane resin and a polyvinyl chloride resin.
<4> The synthetic resin skin material according to any one of <1> to <3>, further comprising a base fabric.
<5> The synthetic resin skin material according to <4>, wherein the base fabric is a knitted fabric.
<6> The base fabric has a 10 kgf (98 N) constant load elongation rate in the width direction at 23 ° C., measured at a load of 10 kgf (98 N) in accordance with ASTM D 3107 (2019), of 40% to 150%, and a 10 kgf (98 N) constant load set rate in the width direction at 23 ° C. of 0.5% to 15%. The synthetic resin skin material according to <4> or <5>, which is a knitted fabric.

According to one embodiment of the present invention, it is possible to provide a synthetic resin skin material that has good moldability at room temperature.

FIG. 1 is a schematic cross-sectional view showing one embodiment of a synthetic resin skin material according to the present disclosure. FIG. 2 is a schematic cross-sectional view showing another embodiment of the synthetic resin skin material of the present disclosure. FIG. 1 is a perspective view of a molding die A, which is one embodiment of a die used when molding a synthetic resin skin material in an embodiment of the present disclosure. FIG. 11 is a perspective view of a molding die B, which is another embodiment of a die used when molding a synthetic resin skin material in an embodiment of the present disclosure.

The synthetic resin skin material of the present disclosure will be described in detail below.
The following description of the configuration elements may be based on representative embodiments of the present disclosure, but the present disclosure is not limited to such embodiments.

In the present disclosure, the use of "to" indicating a range of values means that the values before and after the range are included as the lower limit and upper limit.
In the numerical ranges described in the present disclosure in stages, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. In addition, in the numerical ranges described in the present disclosure, the upper or lower limit value of the numerical range may be replaced with a value shown in the examples.

In the present disclosure, combinations of two or more preferred aspects are more preferred aspects.
In the present disclosure, when a plurality of substances corresponding to each component are present in the composition, the amount of each component in the composition means the total amount of the plurality of substances present in the composition, unless otherwise specified.

In the present disclosure, the term "step" refers not only to an independent step, but also to a step that cannot be clearly distinguished from other steps, as long as the intended purpose of the step is achieved.
In this disclosure, the length direction of a synthetic resin skin material refers to the direction parallel to the conveying direction of a manufacturing device that manufactures a long synthetic resin skin material, and the width direction refers to the direction perpendicular to the length direction on the surface of the synthetic resin skin material.

In the case of a synthetic resin skin material that is a single-layer or multi-layer skin material containing resin, the length and width directions can be confirmed by observing the orientation of the resin with a transmission electron microscope. In the case of a synthetic resin skin material that has a base fabric, the length and width directions can be confirmed by observing the structure of the base fabric.

In the present disclosure, 1 kgf is 9.8 N.
In this disclosure, "room temperature" refers to 23°C unless otherwise specified.
In the present disclosure, the moldability at room temperature (room temperature processability) refers to the moldability when the temperature of the synthetic resin skin material to be processed is room temperature.

In this disclosure, the term "layer containing a resin" refers to a layer formed containing a resin that is the main component of the layer. In other words, in this disclosure, the term "layer containing a resin" is used to include both a resin layer containing only a resin, and a layer formed from a resin composition that contains, in addition to the main component resin, optional components such as a plasticizer, a colorant, and an ultraviolet absorber.

Here, in this disclosure, the "resin that is the main component" refers to a resin that is contained in an amount of 60 mass% or more based on the total amount of the resin composition that contains that component. In this disclosure, the resin that is the main component that constitutes the layer is also referred to as the "base resin."

In the present disclosure, the term "molded article" refers to a molded article (a base of a molded article) before decoration.
Hereinafter, in this disclosure, the synthetic resin skin material may be simply referred to as the "skin material."
[Synthetic resin skin material]
The synthetic resin skin material of the present disclosure (hereinafter sometimes simply referred to as the "skin material of the present disclosure") has a skin layer containing a resin, and has a 1 kgf (9.8 N) constant load elongation rate in the width direction at 23°C, measured at a load of 1 kgf in accordance with ASTM D 3107 (2019), of 7% to 100%, and a 1 kgf (9.8 N) constant load set rate in the width direction at 23°C of 0.5% to 15%.

Synthetic resin skin materials are often used for molded articles that have a three-dimensional shape in both the vertical and horizontal directions, such as vehicle doors. In this case, it is preferable for the skin material to have a certain degree of elasticity in both the vertical and horizontal directions. According to the inventor's research, it has been found that by having a certain degree of elasticity in the vertical direction of the molded article, i.e., in the width direction of the skin material, as described in detail below, the molding processability at room temperature when used for a molded article is good.

The skin material of the present disclosure has at least a skin layer containing a resin. As described in detail below, the skin material of the present disclosure may have a single-layer structure consisting of only the skin layer, or may have a multi-layer structure including the skin layer and any other layers.

In both the single-layer structure and the multi-layer structure, the skin material of the present disclosure has a 1 kgf constant load elongation rate in the width direction at 23°C, measured at a load of 1 kgf in accordance with ASTM D 3107 (2019), of 7% to 100%, and a 1 kgf constant load set rate in the width direction at 23°C, of 0.5% to 15%.

Since the elongation rate at 1 kgf constant load at 23° C. in the width direction of the skin material and the set rate at 1 kgf constant load at 23° C. in the width direction are both within the above-mentioned ranges, the stretchability properties in the width direction of the skin material of the present disclosure are adjusted to fall within a suitable range, and the molding processability at room temperature is excellent.
(1 kgf constant load elongation rate)
The 1 kgf constant load elongation of the skin material of the present disclosure is measured in accordance with ASTM D 3107 (2019).

The 1 kgf constant load elongation rate can be measured using a constant load elongation tester.
In the present disclosure, the values measured using a constant load elongation tester (FLM-6M (product name), manufactured by Daiei Scientific Instruments Manufacturing Co., Ltd.) are used.

The measurement sample used is a test piece cut from the skin material to a width of 80 mm and a length of 200 mm.
The test piece is fixed to the constant load elongation tester, and the elongation is measured at a load of 1 kgf (9.8 N) in accordance with ASTM D 3107 (2019). The measurement conditions are as follows.

Gauge line spacing 100mm
Grip distance: 150 mm
Load: 1kgf (9.8N)
Time Loading 10 minutes
Depressurize for 10 minutes Ambient temperature 23℃±2℃
The 1 kgf constant load elongation rate is calculated using the following formula.

Constant load elongation rate (%) = {(L1-L0)/L0} x 100
In the above formula, L0 represents the gauge length (mm) before the test, and L1 represents the gauge length (mm) 10 minutes after the load is applied.

The elongation rate in the width direction under a constant load of 1 kgf at 23° C. calculated by the above formula is from 7% to 100%, and preferably from 15% to 60%.
(1kgf constant load set rate)
The 1 kgf constant load set rate of the skin material of the present disclosure is measured at a load of 1 kgf in accordance with ASTM D 3107 (2019).

The 1 kgf constant load set rate can also be measured using a constant load elongation tester.
In the present disclosure, the 1 kgf constant load set rate is measured using the same testing machine used to measure the 1 kgf constant load elongation rate.

The measurement samples and measurement conditions are also the same.
The 1 kgf constant load set rate is calculated using the following formula.
Constant load set rate (%) = {(L2 - L0) / L0} x 100
In the above formula, L0 represents the gauge length (mm) before the test, and L2 represents the gauge length (mm) 10 minutes after the weight was removed.

The set rate in the width direction at a constant load of 1 kgf at 23° C. calculated by the above formula is 0.5% to 15%, and preferably 0.5% to 10%.
The skin material of the present disclosure preferably has a 1 kgf constant load elongation in the length direction at 23°C, measured at a load of 1 kgf in accordance with ASTM D 3107 (2019), of 7% to 100%, and a 1 kgf constant load set rate in the length direction at 23°C of 0.5% to 15%.

The 1 kgf constant load elongation rate and 1 kgf constant load set rate in the length direction at 23°C can be measured in the same manner as in the width direction by changing the width direction of the test piece to the length direction.

The measured elongation rate under a constant load of 1 kgf at 23° C. in the longitudinal direction is preferably 7% to 100%, and more preferably 15% to 60%.
The set rate measured in the length direction under a constant load of 1 kgf at 23° C. is preferably 0.5% to 15%, and more preferably 0.5% to 10%.

Since the elongation rate at 1 kgf constant load at 23° C. in the lengthwise direction as well as the widthwise direction of the skin material and the set rate at 1 kgf constant load at 23° C. in the lengthwise direction are all within the above-mentioned ranges, the stretch properties in the lengthwise and widthwise directions of the skin material of the present disclosure are adjusted to be within suitable ranges, and the molding processability at room temperature is improved.
[Layer structure of skin material]
Next, the layer structure of the skin material will be described.

As described above, the skin material of the present disclosure may be a single-layer structure consisting of only a skin layer containing a resin, or may be a multi-layer structure including any other layer in addition to the skin layer.
Fig. 1 is a schematic cross-sectional view showing one embodiment of a skin material according to the present disclosure. The skin material 10 shown in Fig. 1 has a skin layer 12 and a surface treatment layer 14 provided on one side of the skin layer 12. The surface treatment layer 14 in Fig. 1 is an optional layer provided to adjust at least one of the appearance and the feel of the skin material 10.

In addition, in each drawing of this disclosure, components indicated by the same reference numerals are meant to be the same components.
Fig. 2 is a schematic cross-sectional view showing another embodiment of the skin material of the present disclosure. The skin material 20 shown in Fig. 2 has a layer structure in which, in a laminate of the skin layer 12 and the surface treatment layer 14 as shown in Fig. 1, the skin layer 12 has an adhesive layer 16 on the side opposite to the side having the surface treatment layer 14, and the skin layer and the base fabric 18 are bonded via the adhesive layer 16. The skin material 20 shown in Fig. 2 has, on the base fabric 18, the adhesive layer 16, the skin layer 12, and the surface treatment layer 14 in this order from the base fabric 18 side. The surface treatment layer 14, the adhesive layer 16, and the base fabric 18 shown in Fig. 2 are optional layers that are provided as desired.
[Epidermal layer]
The skin layer is a required layer of the skin of the present disclosure.

The skin layer is a layer containing a resin.
-resin-
There is no particular limitation on the resin contained in the skin layer, and any resin that can be molded into a sheet can be used. Examples of the resin include urethane resin, polyvinyl chloride resin (hereinafter sometimes abbreviated as PVC), acrylic resin, polyester resin, silicone resin, polyolefin resin, polystyrene elastomer resin, etc.

Among these, it is preferable to use at least one resin selected from the group consisting of urethane resin and polyvinyl chloride resin, from the viewpoint that it is easy to adjust the 1 kgf constant load elongation rate and 1 kgf constant load set rate under 23°C conditions to a preferred range and to easily obtain various performance properties required of the skin material.

Examples of urethane resins contained in the skin layer include polycarbonate-based polyurethane, polyether-based polyurethane, polyester-based polyurethane, and modified products thereof. Among these, polycarbonate-based polyurethane is more preferred from the viewpoint of ease of achieving the various performance properties required of the skin material.

When the surface layer contains a urethane resin, the urethane resin preferably has a hardness, measured at 20° C. in accordance with JIS K 6251 (1993), in the range of 4 MPa (4×10 ⁶ N/m ² ) to 40 MPa at 100% modulus.

When the hardness of the resin measured at 20°C is within the above range, it becomes easier to control the elastic properties of the skin material obtained using the resin, i.e., the constant load elongation rate and constant load set rate, within a preferred range.

Methods for adjusting the hardness (100% modulus) of urethane resin include, for example, increasing the ratio of polyol components that form soft segments or increasing the molecular weight of polyol to make it softer, and increasing the number of urethane bonds and urea bonds that form hard segments to make it harder, as well as adding a crosslinking agent such as hexamethylene diisocyanate (HDI), hydrogenated xylylene diisocyanate (hydrogenated XDI), isophorone diisocyanate (IPDI), or dicyclohexylmethane diisocyanate (hydrogenated MDI) to impart energy and form a crosslinked structure.

The PVC contained in the skin layer may be a vinyl chloride homopolymer having an average degree of polymerization of 650 to 1,800, an ethylene/vinyl chloride copolymer, or the like.
-Other additives-
In addition to the above resin, known additives may be added to the surface layer, if necessary, so long as the effect is not impaired.

Examples of additives that the skin layer may contain include colorants, crosslinking agents, crosslinking accelerators, film-forming assistants, flame retardants, and foaming agents.
- Coloring agent -
The surface layer may contain a colorant. By containing a colorant, a desired hue can be imparted to the surface layer, and design properties can be improved.

There are no particular limitations on the colorant, and it can be appropriately selected from pigments, dyes, etc. depending on the purpose.
Examples of colorants include inorganic pigments such as titanium white (titanium dioxide), zinc white, ultramarine, cobalt blue, red iron oxide, vermilion, yellow lead, titanium yellow, and carbon black, organic pigments or dyes such as quinacridone, permanent red 4R, isoindolinone, Hansa Yellow A, phthalocyanine blue, indanthrene blue RS, and aniline black, metal pigments selected from the group consisting of foil powders of metals such as aluminum and brass, and pearlescent (pearl) pigments selected from the group consisting of foil powders of titanium dioxide-coated mica and basic lead carbonate, etc. Among these, pigments are preferred as colorants from the viewpoint of better durability and light resistance.

When the surface layer contains a pigment as the colorant, a pigment dispersant such as a surfactant or a polymer dispersant may be used in combination.
When the surface layer contains a colorant, the content of the colorant can be, for example, in the range of 0.5% by mass to 50% by mass, and preferably in the range of 5% by mass to 25% by mass, relative to the total mass of the surface layer.
-Additives other than colorants-
The skin layer may further include additives other than colorants.

For example, the surface layer may contain a known flame retardant such as a phosphorus-based, halogen-based, or inorganic metal-based flame retardant, thereby improving the flame retardancy of the surface material.
[Formation of epidermal layer]
The skin layer can be formed by a known method.

The skin layer can be formed by preparing a composition for forming the skin layer that contains a resin and, if desired, additives such as a colorant and a solvent, and molding the resulting composition for forming the skin layer.

The composition for forming the surface layer can be prepared by dissolving the resin in a solvent. Solvents that can be used to prepare the composition for forming the surface layer include dimethylformamide (DMF), methyl ethyl ketone (MEK), isopropyl alcohol (IPA), toluene, etc., and mixed solvents of two or more of these.

Hereinafter, the solvents may be referred to by the above-mentioned abbreviations.
The surface layer can be formed by forming a film from a composition for forming a surface layer by a known film forming method such as a calendar method, a paste processing method, or a melt extrusion method.

The skin layer can also be formed by applying the composition for forming the skin layer onto a release paper. Either a release paper for transferring a grain pattern or a smooth release paper can be used as the release paper. By using a release paper for transferring a grain pattern, a rough pattern called a grain pattern can be formed on the surface of the skin layer.

The thickness of the skin layer is appropriately selected depending on the intended use of the skin material. From the viewpoint of improving the moldability and texture of the skin material, the thickness of the skin layer after drying is preferably 10 μm to 500 μm, and more preferably 20 μm to 150 μm.

When there are two or more skin layers, the thickness of the skin layer refers to the total thickness of the multiple skin layers.
The thickness of the substrate layer and the thickness of each layer of the skin material described below can be measured by observing a cut surface of the skin material cut perpendicular to the surface direction. In the present disclosure, the thickness of the skin layer is determined by measuring the thickness of five randomly selected points on the cut surface and taking the arithmetic average value. The thicknesses of the other layers can be measured in the same manner.

Therefore, in this disclosure, the thickness of each layer in the skin material refers to the thickness of each layer after it has been dried.
As described above, the skin material of the present disclosure may have a single-layer structure consisting of a skin layer containing a resin. In the case of a single-layer skin material, it is preferable that the physical properties of the skin layer itself are such that the elongation rate at 1 kgf constant load in the width direction at 23° C. is 7% to 100% and the set rate at 1 kgf constant load in the width direction at 23° C. is 0.5% to 15%.

In the case of a single-layer skin material, the above physical properties can be achieved by controlling the type, molecular weight, and content of the resin contained in the skin layer, as well as the formulation and thickness of the composition for forming the skin layer, including additives that are optionally contained. The thickness of the skin layer is appropriately adjusted within the above range.
[Other layers]
The skin material of the present disclosure may further include layers other than the skin layer (hereinafter, sometimes referred to as "other layers").

Examples of the other layers include a base fabric that serves as the substrate for the skin material, an adhesive layer, a surface treatment layer, a primer layer, and an intermediate layer.
(base fabric)
The covering material of the present disclosure may have a base fabric.

There are no particular limitations on the base fabric, so long as it has the necessary strength and flexibility, and the resulting skin material has the desired stretchability.
Examples of fibers used for the base fabric include synthetic fibers such as polyester, polyamide, polyacrylonitrile, and polyvinyl alcohol, and natural fibers such as cotton and hemp, and may be selected according to the purpose.

When the covering material has a base fabric, the elasticity of the covering material may be affected by the elasticity of the base fabric. For this reason, when selecting the base fabric, it is preferable to take into consideration the elasticity of the base fabric alone in addition to its strength and flexibility.

The base fabric may be any of woven fabric, knitted fabric, and nonwoven fabric. Among them, knitted fabric is preferred from the viewpoint of easily imparting a certain degree of stretchability in the width direction of the skin material.
Examples of knitted fabrics include warp knitted tricot knitted fabrics, double raschel knitted fabrics, circular knitted pique knitted fabrics, interlock knitted fabrics, mocrody knitted fabrics, and weft knitted fabrics, with interlock knitted fabrics, which are a type of double-sided knitting, being more preferred.

The basis weight of the base fabric used for the skin material is preferably 30 g/m ² to 400 g/m ² , and more preferably 30 g/m ² to 300 g/m ² , from the viewpoint of better molding processability, appearance after molding, and texture.

The basis weight of the base fabric, for example, in the case of a knitted fabric, can be adjusted by the structure of the knitted fabric, the thickness of the fibers used in knitting, the structure, the density of the fibers, and the like.
The thickness of the base fabric used for the skin material is preferably 0.2 mm to 1.4 mm, and more preferably 0.2 mm to 1.0 mm, from the viewpoints of better molding processability, appearance after molding, and texture.

From the viewpoint of the elasticity characteristics of the base fabric, the 10 kgf constant load elongation rate at 23°C measured at a load of 10 kgf (98 N) in accordance with ASTM D 3107 (2019) of the base fabric alone is preferably 40% to 150% in the width direction, and more preferably 40% to 130%. In addition, the constant load set rate at 23°C measured at a load of 10 kgf (98 N) in accordance with ASTM D 3107 (2019) of the base fabric alone is preferably 0.5% to 15% in the width direction, and more preferably 3% to 10%.

Furthermore, the constant load elongation at 23°C measured on the base fabric alone in the same manner as above is preferably 40% to 150% in the length direction, and more preferably 40% to 130%. Also, the constant load set rate at 23°C is preferably 0.5% to 15% in the length direction, and more preferably 3% to 10%.

When the constant load elongation rate and constant load set rate of the base fabric alone measured by the above method are within the above ranges, it tends to be easier to adjust the constant load elongation rate and constant load set rate of the skin material having the base fabric to the above-mentioned physical properties.

The constant load elongation rate and constant load set rate of the base fabric alone can be measured in the same manner as the constant load elongation rate and constant load set rate of the skin material described above, using a constant load elongation tester, such as FLM-6M (product name) manufactured by Daiei Kagaku Seiki Seisakusho Co., Ltd., in accordance with ASTM D 3107 (2019). For the measurement, a test piece cut from the base fabric to a width of 80 mm and a length of 200 mm is used.

The constant load elongation rate and constant load set rate of the base fabric are calculated using the following formulas.
Constant load elongation rate (%) = {(L1-L0)/L0} x 100
Constant load set rate (%) = {(L2 - L0) / L0} x 100
In the above formula, L0 represents the gauge length (mm) before the test, L1 represents the gauge length (mm) 10 minutes after the load is applied, and L2 represents the gauge length (mm) 10 minutes after the load is removed.

The measurement conditions when the base fabric is measured alone are as follows.
Gauge line spacing 100mm
Grip distance: 150 mm
Load: 10kgf (98N)
Time Loading 10 minutes
Depressurize for 10 minutes Ambient temperature 23℃±2℃
That is, the constant load elongation rate and constant load set rate measured on the base fabric alone are values measured under load conditions different from those in the measurements on the skin material.
(Adhesive layer)
The skin material of the present disclosure may have an adhesive layer. For example, when the skin material has a base fabric, the adhesive layer may be provided between the skin layer and the base fabric to improve the adhesion between the base fabric and the skin layer. Also, when an optional layer is provided between the skin layer and the base fabric, the adhesiveness between the optional layer formed adjacent to the base fabric and the base fabric can be improved.

There are no particular limitations on the adhesive that constitutes the adhesive layer, and examples include adhesives that contain resins such as urethane resin, polyvinyl chloride, polyvinylidene chloride, polystyrene, and acrylic resin.

Examples of urethane resins contained in the adhesive include resins selected from polycarbonate-based polyurethanes, polyether-based polyurethanes, polyester-based polyurethanes, and modified versions of these.

Among these, from the viewpoint of improving the various performance characteristics required of the skin material, adhesives containing urethane resin or polyvinyl chloride resin are preferred, and adhesives containing polycarbonate-based polyurethane are more preferred.

From the viewpoint of improving adhesion between the base fabric and the adjacent layer and improving moldability, the resin contained in the adhesive preferably has a 100% modulus at 20°C of 1.0 MPa to 6.0 MPa, and more preferably 1 MPa to 3 MPa.

The thickness of the adhesive is preferably 2.0 μm to 80.0 μm, and more preferably 25.0 μm to 60.0 μm, from the viewpoint of improving the adhesion between adjacent layers and providing a better texture.

The thickness of the adhesive layer can be controlled by the amount of adhesive applied.
(Surface treatment layer)
The skin material of the present disclosure may have a surface treatment layer. For example, when the skin material of the present disclosure has a base fabric, the surface treatment layer may be provided on the surface of the skin layer opposite to the surface on the base fabric side. The surface treatment layer is generally provided on the outermost surface of the skin material for the purpose of improving at least one of the appearance, texture (feel) and abrasion resistance of the skin material.

Resins contained in the surface treatment layer include polyurethane, acrylic resin, fluororesin, polyvinyl chloride resin, etc., and it is preferable that the surface treatment layer contains polyurethane as the main component, from the viewpoint of further improving abrasion resistance and texture.

Polyurethanes that can be used include polycarbonate-based polyurethanes, polyether-based polyurethanes, polyester-based polyurethanes, and modified versions of these. From the viewpoint of the various performance properties required of the skin material, it is preferable that the surface treatment layer contains polycarbonate-based polyurethanes.

There are no particular limitations on the method for producing the surface treatment layer, and the surface treatment layer is formed by applying a surface treatment layer forming composition obtained by dissolving the above resin in an appropriate solvent, or a surface treatment agent composition containing the above resin in the form of an aqueous emulsion or dispersion, to the surface of the epidermis layer.

When preparing the composition for forming the surface treatment layer, examples of non-aqueous organic solvents that can be used to dissolve the resin include dimethylformamide (DMF), methyl ethyl ketone (MEK), isopropyl alcohol (IPA), toluene, etc., and mixed solvents of two or more of these.

The aqueous emulsion resin or dispersion resin is a resin dispersion in which the resin is contained in an aqueous medium or a non-aqueous organic solvent (or dispersion medium) in a uniform emulsion state.
The aqueous medium used in the resin dispersion may be water, alcohol, or a mixture of two or more of these. The non-aqueous solvent used in the resin dispersion may be the same as the above-mentioned solvents.

The surface treatment layer may contain other components in addition to the above-mentioned resin and solvent (dispersion medium).
Examples of other components include a crosslinking agent, an organic filler, a lubricant, a flame retardant, etc. For example, when the surface treatment layer contains an organic filler, a lubricant, etc., the surface material is given a smooth feel and the abrasion resistance is further improved.

From the viewpoint of obtaining a sufficient effect of improving the abrasion resistance and texture of the skin material, the thickness of the surface treatment layer is preferably in the range of 1.0 μm to 10.0 μm, and more preferably in the range of 1.0 μm to 7.5 μm.
(Method of manufacturing the skin material)
The method for producing the skin material of the present disclosure is not particularly limited, and the skin material can be produced by any known method.

When the skin material of the present disclosure is a skin material with a single layer structure, a layer containing preferably a urethane resin may be formed by the above-mentioned known method such as extrusion or coating according to the method for forming the skin layer.

When the skin material of the present disclosure has a multi-layer structure, for example, a method can be used in which a skin layer is first formed on the surface of a release paper, and then any desired layers are sequentially formed.
When the multi-layered skin material has a base fabric, the skin material can be obtained by contacting the adhesive layer side of a laminate of a skin layer formed on the surface of a release paper and an adhesive layer formed as required with the prepared base fabric and pressing the laminate together to adhere the skin material to the base fabric.

The skin layer may or may not be formed using release paper. Any known release paper may be used depending on the purpose. The release paper may be a release paper for transferring a grain pattern, or a smooth release paper.

A known method can be used to form a skin layer on the surface of the release paper. A typical method for forming a skin layer is to apply the composition for forming the skin material described above to the surface of the release paper and dry it to form the skin layer. In addition, if there is no problem with transferring the grain pattern, the skin layer may be provided on the surface of the release paper by a transfer method.

The optional adhesive layer can be formed by applying the adhesive layer-forming composition described above to the surface of the skin layer. The adhesive layer-forming composition can be applied to the surface of the skin layer by a coating method or a transfer method.

A heat treatment may be carried out when the laminate and the base fabric are pressed and bonded together, or after the press and bond.
The laminate including the base fabric, the adhesive layer, and the surface layer can be heated by a known method. There are no particular limitations on the heating means, and any known heating means such as heating using a heated roll, heating with hot air, or heating in a heating and drying oven may be used.

Here, it can be said that one of the preferred embodiments is to bond the adhesive layer to the base fabric and perform heat treatment while the adhesive layer is still uncured. By contacting the adhesive layer formed on the surface of the skin layer with the base fabric and applying pressure to bond the adhesive layer, some of the fibers contained in the base fabric can easily penetrate into the adhesive layer, and the adhesive layer and the base fabric can be bonded more closely. Furthermore, the adhesive layer is hardened by the subsequent heat treatment, which improves the adhesiveness with the base fabric, and the resulting skin material has better peel strength between the base fabric and the skin layer.

After the adhesive layer and the skin layer are cured by the heat treatment, the release paper is peeled off from the surface of the skin layer to obtain the skin material.
The above-mentioned method for manufacturing the skin material is merely an example, and other known methods for manufacturing skin materials may be used.

The skin material of the present disclosure has favorable elastic properties, and therefore has good processability at room temperature. It can be applied to the surfaces of various three-dimensional molded articles to give them a good appearance, and has a wide range of applications.
Examples of three-dimensional molded articles to which the skin material of the present disclosure can be applied include vehicle interior materials for automobiles, trains, etc., furniture, aircraft, ships, building decorations, wall decorations, etc., and the skin material of the present disclosure can be suitably used for decorating various molded articles.

The skin material of the present disclosure will be specifically described below with reference to examples, but the present disclosure is not limited to the following specific examples.
In the following examples, the percentages indicating the concentrations and contents of each component are based on mass unless otherwise specified.
Example 1
(Step I: Formation of Epidermal Layer)
The components were thoroughly mixed according to the following recipe to obtain a surface layer forming composition 1 having a solid content of about 13%. The following "(1) one-component resin, polycarbonate-based polyurethane resin having a solid content of 20%" is the main resin in the surface layer.
(Epidermal layer forming composition 1 formulation)
(1) One-component resin: Polycarbonate-based polyurethane resin with 20% solids
(100% modulus at 20°C: 5 MPa) 100 parts by weight (2) Solvent (DMF) 20 parts by weight (3) Solvent (PGM) 15 parts by weight (4) Solvent (IPA) 5 parts by weight (5) Colorant (black pigment: carbon black) 15 parts by weight The surface layer forming composition 1 was applied to a release paper using a knife coater so that the wet application amount was 150 g/ ^m2 .

The formed coating layer of the composition 1 for forming a surface layer was dried at 100° C. for 2 minutes using a hot air dryer to form a surface layer on the release paper. The thickness of the surface layer after drying was about 20 μm.
(Step II: Maturation of the surface layer and removal of the release paper)
The surface layer formed in step I was aged at 50° C. for 48 hours, and then the release paper was peeled off.
(Step III: Formation of surface treatment layer)
The components were thoroughly mixed according to the following recipe to obtain a composition 1 for forming a surface treatment layer having a solid content of about 14%.
(Formulation of surface treatment layer forming composition 1)
(1) One-component resin: Polycarbonate-based polyurethane resin with 15% solids
(2) Solvent (MEK) 5 parts by mass After peeling off the release paper obtained in step II, the composition for forming the surface treatment layer obtained above was applied to one side of the surface layer so as to give a wet application amount of 10 g/ ^m2 .

The coating was heated at 90° C. for 1 minute using a hot air dryer to form a surface treatment layer having a thickness of 1.4 μm on the surface layer.
In this manner, a skin material of Example 1 having the skin layer and the surface treatment layer and having the layer structure shown in FIG. 1 was obtained.
Example 2
The (1) polyurethane resin (main resin) in the composition 1 for forming a skin layer used in the formation of the skin layer in step I of Example 1 was changed to (1-2) a one-component polycarbonate-based polyurethane resin having a solid content of 30% (100% modulus at 20°C: 10 MPa), to obtain a composition 2 for forming a skin layer having a solid content of approximately 16%.

A skin material of Example 2 having a skin layer and a surface treatment layer was obtained in the same manner as in Example 1, except that the skin layer-forming composition 1 was changed to the skin layer-forming composition 2.
Example 3
The (1) polyurethane resin (main resin) in the composition 1 for forming a skin layer used in the formation of the skin layer in step I of Example 1 was changed to (1-3) a one-component polyester polyurethane resin having a solid content of 20% (100% modulus at 20°C: 35 MPa), to obtain a composition 3 for forming a skin layer having a solid content of approximately 13%.

A skin material of Example 3 having a skin layer and a surface treatment layer was obtained in the same manner as in Example 1, except that composition 3 for forming a skin layer was used instead of composition 1 for forming a skin layer.
Example 4
After step I and before step II of Example 1, the following steps IV and V were carried out in this order.
(Step IV: Formation of adhesive layer)
The components were thoroughly mixed according to the following recipe to obtain a composition 1 for forming an adhesive layer having a solid content of about 45%.
(Formulation of adhesive layer forming composition 1)
(1) Two-component polycarbonate-based polyurethane resin with 70% resin solids (100% modulus at 20°C: 2.5 MPa) 100 parts by weight (2) Solvent (DMF) 50 parts by weight (3) Isocyanate-based crosslinking agent 6 parts by weight The adhesive layer-forming composition 1 was applied to the surface of the skin layer formed on the release paper obtained in step I in a wet application amount of 100 g/ ^m2 to form a coating layer.

The coating layer was heated at 120° C. for 2 minutes using a hot air dryer to form an adhesive layer having a thickness of 45 μm on the surface of the skin layer.
(Step V: Lamination of base fabric)
As the base fabric, an interlock knit fabric (basis weight: 110 g/m ² , thickness: 0.7 mm) was prepared.

The adhesive layer formed in step IV was laminated to the above-mentioned base fabric prepared in step IV. The heating temperature during lamination was 130°C.
(Stretchability of base fabric)
For the interlock knitted fabric used in Example 4, the base fabric alone was measured for the 10 kgf constant load elongation rate in the width direction and length direction at 23 ° C. and the 10 kgf constant load set rate in the width direction and length direction at 23 ° C. in accordance with ASTM D 3107 (2019). The results are shown in Table 1 below.

Thereafter, in the same manner as in step III of Example 1, a surface treatment layer was formed on the surface of the skin layer opposite the adhesive layer, to obtain a skin material of Example 4 having the layer structure shown in Figure 2, which has the adhesive layer, the skin layer, and the surface treatment layer in this order on the base fabric.
Example 5
A skin material of Example 5 having an adhesive layer, a skin layer and a surface treatment layer in this order on a base fabric was obtained in the same manner as in Example 4, except that a mocrody knit fabric (basis weight: 390 g/ ^m2 , thickness: 1.2 mm) was used as the base fabric instead of the interlock knit fabric used in Example 4.

The stretch properties of the mocrody knit fabric used in Example 5 were measured in the same manner as in Example 4. The results are shown in Table 1 below.
Example 6
A skin material of Example 6 having an adhesive layer, a skin layer and a surface treatment layer in this order on a base fabric was obtained in the same manner as in Example 4, except that a tricot knit fabric (basis weight: 280 g/ ^m2 , thickness: 0.9 mm) was used as the base fabric instead of the interlock knit fabric used in Example 4.

The stretch properties of the tricot knit fabric used in Example 6 were measured in the same manner as in Example 4. The results are shown in Table 2 below.
Example 7
(Step I: Formation of Epidermal Layer)
The components were thoroughly mixed according to the following recipe to obtain a surface layer forming composition 4 having a solid content of about 100%. The following “(1) polyvinyl chloride resin (average polymerization degree 1300)” is the main resin in the surface layer forming composition 4.
(Epidermal layer forming composition 4 formulation)
(1) Polyvinyl chloride resin (average degree of polymerization: 1,300)
(100% modulus at 20°C: 7 MPa) 100 parts by weight (2) Plasticizer (dialkyl phthalate) 75 parts by weight (3) Stabilizer (Ba-Zn composite stabilizer) 2 parts by weight (4) Filler (calcium bicarbonate) 10 parts by weight (5) Colorant (black pigment: carbon black) 5 parts by weight The surface layer forming composition 4 was applied to a release paper using a knife coater so that the wet application amount was 150 g/ ^m2 .

The resulting coating layer of the surface layer-forming composition 4 was dried at 100°C for 2 minutes using a hot air dryer to form a surface layer on the release paper. The thickness of the surface layer after drying was approximately 150 μm.

A skin material of Example 7 having a skin layer and a surface treatment layer was obtained in the same manner as in Example 1, except that the obtained skin layer was used.
Comparative Example 1
The (1) polyurethane resin in the composition for forming a skin layer 1 used for forming the skin layer in step I of Example 1 was changed to (1-C1) a one-component polyester-based polyurethane resin having a solid content of 20% (100% modulus at 20°C: 2 MPa), to obtain a composition for forming a skin layer C1 having a solid content of approximately 13%.

A skin material of Comparative Example 1 having a skin layer and a surface treatment layer was obtained in the same manner as in Example 1, except that the skin layer-forming composition 1 was changed to the skin layer-forming composition C1.
Comparative Example 2
The (1) polyurethane resin in the composition for forming a skin layer 1 used for forming the skin layer in step I of Example 1 was changed to (1-C2) a one-component polyester-based polyurethane resin having a solid content of 20% (100% modulus at 20°C: 50 MPa), to obtain a composition for forming a skin layer C2 having a solid content of approximately 13%.

A skin material of Comparative Example 2 having a skin layer and a surface treatment layer was obtained in the same manner as in Example 1, except that the skin layer-forming composition 1 was changed to the skin layer-forming composition C2.
Comparative Example 3
A skin material of Comparative Example 3 having an adhesive layer, a skin layer and a surface treatment layer in this order on a base fabric was obtained in the same manner as in Example 4, except that a woven fabric (basis weight: 365 g/ ^m2 , thickness: 0.95 mm) was used as the base fabric instead of the interlock knitted fabric used in Example 4.

The stretch properties of the woven fabric used as the base fabric in Comparative Example 3 were measured in the same manner as in Example 4. The results are shown in Table 2 below.
[Evaluation of skin material]
The following items were evaluated for the skin materials of Examples 1 to 7 and Comparative Examples 1 to 3. The results are shown in Tables 1 and 2.
(1. Measurement of elongation rate under 1 kgf constant load and set rate under 1 kgf constant load at 23° C. in the width direction and length direction)
Using the method described above, the 1 kgf constant load elongation rate and 1 kgf constant load set rate of the skin material were measured in the width direction and length direction at 23° C. under a load of 1 kgf in accordance with ASTM D 3107 (2019).
(2. Evaluation of Light Fastness)
A light resistance test was carried out under the following conditions in accordance with JIS D 0205 (1987), and the covering material was visually observed before and after the test and evaluated according to the following criteria.

Testing machine: Light resistance testing machine (U48AUH (product name) manufactured by Suga Testing Machines Co., Ltd.)
(Test conditions)
Black panel temperature: 83℃
Time: 400 hours Irradiance: 500W/m ² (300nm to 700nm)
(Evaluation Criteria)
A: No visually detectable discoloration of the skin material. B: Slight visual discoloration of the skin material. C: Clear discoloration of the skin material. In the above evaluation criteria, levels A and B are practically acceptable, with level A being preferred.
(3. Evaluation of Moisture and Heat Resistance)
A moist heat resistance test was carried out in accordance with JIS C 60068-3-4 (2004).

Testing machine: Constant temperature and humidity testing machine (PL-3J (product name) manufactured by Espec Corporation)
(Test conditions)
Temperature/Humidity 70℃ x 95%RH
Time 840 hours (evaluation method)
A tensile test was carried out on the skin material before and after the moist heat resistance test, and the strength retention rate (%) after the test relative to the strength before the test was calculated.

The tensile test was carried out in accordance with JIS K 7139 (2009).
Testing machine: Tensile testing machine (Shimadzu Corporation, Autograph AGS-100NX (product name))
(Measurement conditions)
Test piece: Width 30mm, length 150mm
Grip distance: 100 mm
Grip width 50mm
Tensile speed: 100 mm/min
(Evaluation Criteria)
A: Strength retention rate is 80% or more. B: Strength retention rate is 50% or more but less than 80%. C: Strength retention rate is less than 50%. In the above evaluation criteria, levels A and B are practically acceptable, with level A being preferred.
(4. Molding processability)
Compression molding was carried out under the following conditions using a compression molding machine (HC300-05 (product name) manufactured by AS ONE Corporation).

The surface temperature of the skin material was adjusted to 23°C.
The molds used were mold A shown in a perspective view in Fig. 3 and mold B shown in a perspective view in Fig. 4. The reference characters M and C written on each mold indicate the length direction and width direction of the skin material, respectively.

Mold A has convex portions that are parallel to the length direction and have smooth tops, while mold B has convex portions that are densely formed in the shape of truncated quadrangular pyramids in the length direction and width direction, and mold B has a more complex shape in the left-right direction (width direction) compared to mold A.

As the substrate for the molded body, a substrate made of ABS (acrylonitrile/butadiene/styrene copolymer) resin was used, and after applying 150 g/m ² of a chloroprene-based adhesive to the surface of the substrate, the substrate was dried and applied.

The skin material was set so that its width direction was set as the C direction of the mold.
The mold temperature was 40° C. (surface measurement temperature), the molding pressure was 0.25 t, and the pressing time was 60 seconds.

Under the above conditions, the molded body before decoration (the base of the molded body) was placed in the mold, the obtained skin material was laminated on the adhesive-coated surface of the molded body, and the compression molding machine was used to simultaneously form an uneven shape on the molded body using the mold and to compress the skin material onto the molded body, thereby obtaining a molded product with an uneven surface decorated with the skin material.

The appearance of the obtained molded article was visually evaluated according to the following criteria.
(Evaluation Criteria)
A: No wrinkles or sagging visible to the naked eye. B: Slight wrinkles or sagging was observed to the naked eye. C: Significant wrinkles and sagging occurred, resulting in a problem in appearance. In the above evaluation criteria, levels A and B are practically acceptable, with level A being preferred.

From the results in Tables 1 and 2, the skin materials of Examples 1 to 7 all had good light resistance, moist heat resistance, and moldability at room temperature, and were at a level that presented no practical problems.
In contrast, Comparative Example 1, in which the constant load elongation rate was too high, and Comparative Example 2, in which the constant load elongation rate was too low, both had poor molding processability. In addition, Comparative Example 3, which used a base fabric with poor elasticity properties even though the skin layer was good, did not satisfy the constant load elongation rate specified in the present disclosure, and therefore had good light resistance and moist heat resistance but poor molding processability.

The above results show that the skin material of the example has good moldability when molded without any special heating, and is also excellent in light resistance and moist heat resistance, so it is expected to be suitable as a skin material for molded bodies.

The technical concept is described below.
(1) having a surface layer containing a resin,
A synthetic resin skin material having a 1 kgf constant load elongation rate in the width direction at 23°C, measured at a load of 1 kgf in accordance with ASTM D 3107 (2019), of 7% to 100%, and a 1 kgf constant load set rate in the width direction at 23°C of 0.5% to 15%.

(2) The synthetic resin skin material is a synthetic resin skin material according to technical idea (1), in which the 1 kgf constant load elongation rate in the length direction at 23°C, measured at a load of 1 kgf in accordance with ASTM D 3107 (2019), is 7% to 100%, and the 1 kgf constant load set rate in the length direction at 23°C is 0.5% to 15%.

(3) The synthetic resin skin material according to the technical concept (1) or (2), wherein the resin comprises at least one selected from the group consisting of urethane resin and polyvinyl chloride resin.
(4) The synthetic resin skin material according to any one of the technical ideas (1) to (3), further comprising a base fabric.

(5) The synthetic resin skin material according to the technical idea (4), wherein the base fabric is a knitted fabric.
(6) The base fabric is a knitted fabric having a 10 kgf constant load elongation rate of 40% to 150% under 23 ° C. conditions in the width direction measured at a load of 10 kgf in accordance with ASTM D 3107 (2019), and a 10 kgf constant load set rate of 0.5% to 15% under 23 ° C. conditions in the width direction. The synthetic resin skin material according to technical idea (4) or (5).

10, 20 Synthetic resin skin material (skin material)
12 Skin layer 14 Surface treatment layer 16 Adhesive layer 18 Base fabric

Claims (11)

A surface layer containing a resin,
A synthetic resin skin material having a 1 kgf constant load elongation rate in the width direction at 23°C, measured at a load of 1 kgf in accordance with ASTM D 3107 (2019), of 7% to 100%, and a 1 kgf constant load set rate in the width direction at 23°C of 0.5% to 15%. A surface layer containing a resin,
The resin includes a polycarbonate-based polyurethane or a polyester-based polyurethane, and the hardness of the polycarbonate-based polyurethane or the polyester-based polyurethane, measured at 20°C in accordance with JIS K 6251 (1993), is in the range of 4 MPa to 40 MPa at 100% modulus;
A synthetic resin skin material having a 1 kgf constant load elongation rate in the width direction at 23°C, measured at a load of 1 kgf in accordance with ASTM D 3107 (2019), of 7% to 100%, and a 1 kgf constant load set rate in the width direction at 23°C of 0.5% to 15%. A synthetic resin skin material having a skin layer containing a resin, a base fabric, and an adhesive layer provided between the skin layer and the base fabric,
the surface layer comprises a polycarbonate-based polyurethane or a polyester-based polyurethane, the polycarbonate-based polyurethane or the polyester-based polyurethane having a hardness of 4 MPa to 40 MPa at 100% modulus measured at 20°C in accordance with JIS K 6251 (1993);
The basis weight of the base fabric is 30 g/m ² to 400 g/m ² , and the thickness of the base fabric is 0.2 mm to 1.4 mm,
The synthetic resin skin material has a 1 kgf constant load elongation rate in the width direction at 23°C, measured at a load of 1 kgf in accordance with ASTM D 3107 (2019), of 7% to 100%, and a 1 kgf constant load set rate in the width direction at 23°C of 0.5% to 15%. A surface layer containing a resin,
The resin comprises polyvinyl chloride,
A synthetic resin skin material having a 1 kgf constant load elongation rate in the width direction at 23°C, measured at a load of 1 kgf in accordance with ASTM D 3107 (2019), of 7% to 100%, and a 1 kgf constant load set rate in the width direction at 23°C of 0.5% to 15%. A synthetic resin skin material having a skin layer containing a resin, a base fabric, and an adhesive layer provided between the skin layer and the base fabric,
the skin layer comprises polyvinyl chloride;
The basis weight of the base fabric is 30 g/m ² to 400 g/m ² , and the thickness of the base fabric is 0.2 mm to 1.4 mm,
The synthetic resin skin material has a 1 kgf constant load elongation rate in the width direction at 23°C, measured at a load of 1 kgf in accordance with ASTM D 3107 (2019), of 7% to 100%, and a 1 kgf constant load set rate in the width direction at 23°C of 0.5% to 15%. The synthetic resin skin material according to any one of claims 1 to 5, wherein the synthetic resin skin material has a 1 kgf constant load elongation rate in the length direction at 23°C, measured at a load of 1 kgf in accordance with ASTM D 3107 (2019), of 7% to 100%, and a 1 kgf constant load set rate in the length direction at 23°C, of 0.5% to 15%. The synthetic resin skin material according to claim 1 further comprises a base fabric. The synthetic resin skin material according to claim 3, claim 5 or claim 7, wherein the base fabric is a knitted fabric. The synthetic resin skin material according to claim 7 or 8, wherein the base fabric is a knitted fabric in which the base fabric alone has a 10 kgf constant load elongation rate in the width direction at 23°C, measured at a load of 10 kgf in accordance with ASTM D 3107 (2019), of 40% to 150%, and a 10 kgf constant load set rate in the width direction at 23°C of 0.5% to 15%. The synthetic resin skin material according to claim 3 or claim 5, wherein the adhesive layer contains an adhesive containing a urethane resin or a polyvinyl chloride resin, and has a thickness of 2.0 μm to 80.0 μm. Further, the surface treatment layer is provided.
The synthetic resin skin material according to any one of claims 1 to 10, wherein the surface treatment layer is a layer containing a polycarbonate-based polyurethane and having a thickness of 1.0 µm to 10.0 µm.