WO2023127223A1

WO2023127223A1 - Synthetic leather

Info

Publication number: WO2023127223A1
Application number: PCT/JP2022/037430
Authority: WO
Inventors: 雄一角上; 裕太朗奥屋; 一輝小野寺
Original assignee: セーレン株式会社
Priority date: 2021-12-28
Filing date: 2022-10-06
Publication date: 2023-07-06
Also published as: JPWO2023127223A1

Abstract

A synthetic leather according to an embodiment of the present invention comprises a fibrous substrate, a foam layer that contains a vinyl chloride resin and a plasticizer, and a non-foam layer that contains a vinyl chloride resin and a plasticizer. In the foam layer and the non-foam layer, the content of the plasticizer is 60-100 parts by mass with respect to 100 parts by mass of the vinyl chloride resin, the plasticizer contains a phthalic acid ester plasticizer and a polyester plasticizer, and the mass ratio of the phthalic acid ester plasticizer and the polyester plasticizer is 73:27 to 87:13.

Description

Synthetic leather

The present invention relates to synthetic leather.

　Among synthetic leathers, synthetic leathers that have a film whose main component is vinyl chloride resin have high flexibility such as flexibility and flexibility, as well as strength. The strength includes, for example, wear resistance against repeated rubbing. Synthetic leather is used in various fields such as vehicle interior material applications such as vehicle seats and door linings, interior material applications such as furniture and chairs, and fashion applications such as bags and shoes. These applications require a high degree of durability because they are placed under severe conditions of use. In particular, in the case of synthetic leather, which is used where there are many chances of direct or indirect contact with the human body, oil resistance against sebum secreted from the human body and oily ingredients contained in cosmetics is required. In particular, there is a strong demand for durability against higher fatty acids such as oleic acid, which is the main component of sebum.

For example, in Patent Document 1, a surface treatment agent obtained by cross-linking a mixture of polycarbonate urethane and ester urethane with a carbodiimide group-containing cross-linking agent is applied to the surface side of a film containing vinyl chloride resin as a main component. Forming a treated layer is described. In Patent Document 1, by forming the surface treatment layer, in addition to high flexibility and good strength, abrasion resistance against repeated rubbing phenomena and chemical resistance against contact with the human body are obtained. It is described that the property (resistance to oleic acid) can be improved.

WO2017/061611

The synthetic resin leather of Patent Document 1 has good chemical resistance (oleic acid resistance), but higher oil resistance is required.

On the other hand, synthetic leather is required to have a structure that is easy to make, that is, workability (or manufacturability) from the viewpoint of cost reduction and ensuring a certain level of quality.

The present invention has been made in view of such circumstances, and its purpose is to provide a synthetic leather with excellent oil resistance and workability.

The synthetic leather according to the embodiment of the present invention includes a fibrous base material, a foamed layer containing a vinyl chloride resin and a plasticizer, and a non-foamed layer containing a vinyl chloride resin and a plasticizer in this order. Contains synthetic leather. In each of the foamed layer and the non-foamed layer, the content of the plasticizer is 60 to 100 parts by mass with respect to 100 parts by mass of the vinyl chloride resin, and the plasticizer is a phthalate plasticizer. A polyester-based plasticizer is included, and the mass ratio of the phthalate-based plasticizer and the polyester-based plasticizer is 73:27 to 87:13.

According to the embodiment of the present invention, synthetic leather with excellent oil resistance and workability can be provided.

It is a cross-sectional schematic diagram of the synthetic leather which concerns on one Embodiment. It is a cross-sectional schematic diagram of the synthetic leather which concerns on other embodiment. It is a cross-sectional schematic diagram of the synthetic leather which concerns on other embodiment.

The synthetic leather according to this embodiment has a fibrous base material, a foamed layer containing a vinyl chloride resin and a plasticizer, and a non-foamed layer containing a vinyl chloride resin and a plasticizer. The foamed layer and the non-foamed layer contain 60 to 100 parts by mass of plasticizer with respect to 100 parts by mass of vinyl chloride resin. The plasticizers used in the foaming layer and the non-foaming layer are a phthalate plasticizer and a polyester plasticizer, and the mass ratio of the phthalate plasticizer and the polyester plasticizer is 73:27 to 87: 13. By adopting such a configuration, it is possible to obtain a synthetic leather having good oil resistance, good workability in a casting method, and a soft texture.

FIG. 1 schematically shows the cross-sectional structure of synthetic leather 1 according to one embodiment. In this synthetic leather 1, a foam layer 3 and a non-foam layer 4 are laminated in this order on one side of a fibrous base material 2. As shown in FIG.

FIG. 2 schematically shows a cross-sectional structure of synthetic leather 10 according to another embodiment. In this synthetic leather 10, the foam layer 3 is provided on the fibrous base material 2 via the adhesive layer 5, and the protective layer 6 is provided on the non-foam layer 4. Synthetic leather 1 is different. Therefore, in the example of FIG. 2, the adhesive layer 5, the foam layer 3, the non-foam layer 4, and the protective layer 6 are laminated in this order on one surface of the fibrous base material 2. As shown in FIG.

FIG. 3 schematically shows a cross-sectional structure of synthetic leather 100 according to another embodiment. This synthetic leather 100 differs from the synthetic leather 10 of FIG. 2 in that a protective layer 6 is provided on the non-foamed layer 4 via an undercoat layer 7 . Therefore, in the example of FIG. 3, the adhesive layer 5, the foam layer 3, the non-foam layer 4, the undercoat layer 7, and the protective layer 6 are laminated in this order on one surface of the fibrous base material 2. there is

　In the examples of Figures 1 to 3, the front surface of the synthetic leather is provided with unevenness such as a grain pattern in consideration of the design, but it may be flat. Here, the front surface of the synthetic leather refers to the surface (design surface) of the front and back surfaces of the synthetic leather that is visible during use. Specifically, the front surface is the surface of the non-foamed layer or protective layer.

The fibrous base material is not particularly limited, and for example, fiber fabrics such as woven fabrics, knitted fabrics, and non-woven fabrics, natural leather (including split leather), and the like can be used. As the fiber fabric, one obtained by applying or impregnating a conventionally known solvent-based or solvent-free polymer compound and then dry-coagulating or wet-coagulating it may be used. The solventless systems referred to herein include aqueous systems. Further, examples of the polymer compound include polyurethane resins and vinyl chloride resins. Among them, knitted fabrics are preferable as the fibrous base material, and circular knitted fabrics are more preferable, from the viewpoint of leather-like properties (specifically, the texture, thickness, and texture of natural leather), strength, and elongation properties. preferable.

The type of fiber in the fiber fabric is not particularly limited, and conventionally known fibers such as natural fibers, regenerated fibers, semi-synthetic fibers, and synthetic fibers can be mentioned. good. Among these fibers, synthetic fibers are preferable, and polyester fibers are more preferable, from the viewpoint of strength and workability.

The shape of the fibers is also not particularly limited, and may be either long fibers or short fibers. The form of the yarn constituting the fibrous base material may be short fiber yarn such as spun yarn, long fiber yarn such as multifilament yarn or monofilament yarn, or long and short composite spun yarn combining long fibers and short fibers. good. From the viewpoint that flexibility can be imparted to the fibrous base material to be obtained, short fibers that have been pre-crimped may be used as the yarn, and the yarn is subjected to false twisting, fluid agitation treatment, or the like. It may be processed.

The fibrous base material may be colored with dyes or pigments.

The synthetic leather according to this embodiment includes a foam layer and a non-foam layer as resin layers containing a vinyl chloride resin and a plasticizer. The foam layer is a resin layer having cells, and may be a porous layer. The non-foamed layer is a resin layer having no air bubbles, unlike the foamed layer. The non-foamed layer is a resin layer laminated on the surface of the foamed layer, and is also called a skin layer.

The vinyl chloride resin that constitutes the non-foamed layer is a polymer composed of vinyl chloride and/or vinylidene chloride as a monomer component. The vinyl chloride resin is not particularly limited, and conventionally known vinyl chloride resins can be used. Examples thereof include vinyl chloride resin and/or vinylidene chloride resin. Examples of vinyl chloride resins include polyvinyl chloride, which is a homopolymer of vinyl chloride, and copolymers of vinyl chloride and other monomers. Vinylidene chloride resins include, for example, polyvinylidene chloride, which is a homopolymer of vinylidene chloride, and copolymers of vinylidene chloride with other monomers. These can be used individually by 1 type or in combination of 2 or more types. Other monomers to be copolymerized with vinyl chloride or vinylidene chloride include, for example, vinyl acetate, ethylene, propylene, styrene, acrylic acid, acrylic acid esters, methacrylic acid, methacrylic acid esters, maleic acid, maleic acid, Examples include acid esters and higher vinyl ethers, and vinyl chloride and vinylidene chloride may be copolymerized.

It is preferable that the resin component constituting the non-foamed layer is mainly composed of vinyl chloride resin. Specifically, it is preferable that more than 50% by mass of the resin component is a vinyl chloride resin, more preferably 80% by mass or more of the resin component is a vinyl chloride resin, and 100% by mass of the resin component is a vinyl chloride resin. Resin may be used. In the present specification, the resin component refers to a polymer component, excluding additives such as plasticizers and heat stabilizers, among the components constituting the resin layer.

The non-foaming layer contains a phthalate plasticizer and a polyester plasticizer as plasticizers. By using the phthalate plasticizer and the polyester plasticizer together, the viscosity of the resin composition liquid for the non-foaming layer can be kept low. Therefore, it is possible to suppress the generation of bubbles and processing streaks, and to form a uniform coating. Therefore, the workability, particularly the workability of the casting method, is improved. Here, the processing streak refers to a streak-like defect that occurs along the application direction when the resin composition liquid is applied. A polyester plasticizer has a larger molecular weight than other plasticizers. Therefore, by using a polyester-based plasticizer, the diffusion rate of the plasticizer is reduced, and the plasticizer is less likely to migrate from the inside of the non-foamed layer to the outside of the non-foamed layer. Therefore, the oil resistance of the obtained synthetic leather can be improved.

A phthalate plasticizer is a phthalate that acts as a plasticizer for vinyl chloride resin. Examples of phthalate plasticizers include dibutyl phthalate (DBP), dioctyl phthalate (DOP), dinonyl phthalate (DNP), diisononyl phthalate (DINP), diisodecyl phthalate (DIDP), ditridecyl phthalate ( DTDP), diundecyl phthalate (DUP), benzylbutyl phthalate (BBP), nonylundecyl phthalate (NUP), dialkyl phthalate (C9-C11), and the like. These can be used individually by 1 type or in combination of 2 or more types. Since these are esters of phthalic acid and monohydric alcohol, the phthalate-based polyester as a polyester-based plasticizer described later is not included in the phthalate-based plasticizer.

In one embodiment, the phthalate ester plasticizer is preferably a dialkyl phthalate, which is an ester of phthalic acid and at least one monohydric alcohol selected from the group consisting of alcohols having 4 to 20 carbon atoms. Among them, dialkyl phthalate (C9 to C11) is preferable from the viewpoint of bleeding resistance, cold resistance and heat resistance. Here, the dialkyl phthalate (C9-C11) is an ester of a mixture of alcohols having 9-11 carbon atoms and phthalic acid.

A polyester plasticizer is a polyester that acts as a plasticizer for vinyl chloride resin. Polyester plasticizers include those obtained by polycondensation of dicarboxylic acids and dihydric alcohols, such as adipic acid polyesters, sebacic acid polyesters, and phthalic acid polyesters. These can be used individually by 1 type or in combination of 2 or more types. Dihydric alcohols include, for example, ethylene glycol, propylene glycol, butanediol (eg 1,3-butanediol, 1,4-butanediol), and hexanediol (eg 1,6-hexanediol). These can be used individually by 1 type or in combination of 2 or more types. As the polyester-based plasticizer, adipic acid-based polyester is preferable from the viewpoint of versatility.

The number average molecular weight (Mn) of the polyester plasticizer is not particularly limited, and is preferably 500-2500, more preferably 1200-2000. When the number average molecular weight is 2500 or less, the viscosity of the resin composition liquid for the non-foaming layer can be kept low, and the processability, particularly the processability of the casting method, can be further improved. When the number average molecular weight is 500 or more, good oil resistance can be obtained. Here, the number average molecular weight of the polyester plasticizer is calculated as a polystyrene-equivalent value measured by a gel permeation chromatography (GPC) method.

The viscosity of the polyester plasticizer is not particularly limited, and is preferably 150 to 5000 mPa·s, more preferably 2000 to 5000 mPa·s. When the viscosity is 150 mPa·s or more, the resulting synthetic leather has good oil resistance. When the viscosity is 5000 mPa·s or less, the viscosity of the resin composition liquid for the non-foaming layer can be kept low, and the processability, particularly the processability of the casting method, can be further improved. Here, the viscosity of the polyester plasticizer is the viscosity at 25 ° C. measured using a Brookfield viscometer, and more specifically, a BII viscometer (BHII type, manufactured by Toki Sangyo Co., Ltd., rotor No. 3) at 10 rpm and a liquid temperature of 25°C.

In the non-foaming layer, the mass ratio of the phthalate plasticizer and the polyester plasticizer (blending ratio as solid content) is (amount of phthalate plasticizer):(amount of polyester plasticizer) = 73:27 to 87:13, preferably 77:23 to 83:17. When the blending ratio of the phthalate plasticizer is 73% by mass or more (that is, the blending ratio of the polyester plasticizer is 27% by mass or less), the viscosity of the resin composition liquid for the non-foaming layer can be kept low. , the workability, especially the workability by the casting method is improved. Good oil resistance is obtained when the blending ratio of the phthalate plasticizer is 87% by mass or less (that is, the blending ratio of the polyester plasticizer is 13% by mass or more).

In the present specification, the mass ratio of the phthalate ester plasticizer and the polyester plasticizer is obtained by rounding off the decimal point when the ratio of each has a fraction after the decimal point when the total of both is 100. It is an integer ratio.

In this specification, solid content refers to components other than volatile substances such as organic solvents and water, and is also referred to as evaporation residue or non-volatile content. Therefore, liquids that do not evaporate at ordinary drying temperatures, such as plasticizers, are also included in the solid content.

The content of the plasticizer in the non-foaming layer (the total content of the phthalate plasticizer and the polyester plasticizer) is 60 to 100 parts by mass with respect to 100 parts by mass of the vinyl chloride resin, preferably 65 to 85 parts by mass. When the amount of the plasticizer is 60 parts by mass or more, a soft texture can be obtained. In addition, the viscosity of the resin composition liquid for the non-foaming layer can be kept low, and the processability, particularly the processability by the casting method, is improved. When the amount of the plasticizer is 100 parts by mass or less, the strength can be improved. Moreover, since the bleeding of the plasticizer can be suppressed, the designability can be improved.

The non-foaming layer can contain conventionally known additives as needed within a range that does not impair its physical properties. Examples of such additives include plasticizers other than phthalate plasticizers and polyester plasticizers, thermoplastic resins and thermosetting resins other than vinyl chloride resins, heat stabilizers, fillers, pigments, Amine-resistant agents, flame retardants, conductivity-imparting agents, antistatic agents, ultraviolet absorbers, light stabilizers, antioxidants, pigment dispersants, cross-linking agents, thickeners, etc., may be used alone or in combination of two. The above can be used in combination.

Examples of the heat stabilizer include metal soaps such as calcium stearate, magnesium stearate, aluminum stearate, barium stearate, zinc stearate, calcium laurate, barium laurate, and zinc laurate; sodium phenol and/or naphthol; Salts, metal salts such as zinc salts and barium salts, organotin compounds such as dibutyltin dilaurate and dibutyltin dimalate, and phosphites such as triphenylphosphite, tricresylphosphite and triisooctylphosphite. be done. These can be used individually by 1 type or in combination of 2 or more types. In one embodiment, an organic acid calcium salt and/or an organic acid zinc salt may be used as a thermal stabilizer. The content of the heat stabilizer is not particularly limited, and may be, for example, 0.1 to 10 parts by mass or 0.5 to 5 parts by mass with respect to 100 parts by mass of the vinyl chloride resin.

Examples of the amine-resistant agents include perchlorates such as sodium perchlorate and potassium perchlorate. These can be used individually by 1 type or in combination of 2 or more types. The content of the amine-resistant agent is not particularly limited, and may be, for example, 0.05 to 5 parts by mass or 0.1 to 2 parts by mass with respect to 100 parts by mass of the vinyl chloride resin.

Although the thickness of the non-foamed layer is not particularly limited, it is preferably 100-300 μm, more preferably 130-250 μm. Good strength is obtained when the thickness of the non-foamed layer is 100 μm or more. When the thickness of the non-foamed layer is 300 μm or less, the thickness of the non-foamed layer of the obtained synthetic leather can be made uniform.

The vinyl chloride resin that constitutes the foam layer is a polymer composed of vinyl chloride and/or vinylidene chloride as a monomer component. The vinyl chloride-based resin is not particularly limited, and the same vinyl chloride-based resin as that used for the non-foamed layer can be used, so the description thereof is omitted. The vinyl chloride resin contained in the foam layer and the vinyl chloride resin contained in the non-foam layer may be the same or different.

It is preferable that the resin component constituting the foam layer is mainly composed of vinyl chloride resin. Specifically, it is preferable that more than 50% by mass of the resin component is a vinyl chloride resin, more preferably 80% by mass or more of the resin component is a vinyl chloride resin, and 100% by mass of the resin component is a vinyl chloride resin. Resin may be used.

The foam layer contains a phthalate plasticizer and a polyester plasticizer as plasticizers. By using a phthalate plasticizer and a polyester plasticizer in combination, the viscosity of the resin composition liquid for the foam layer can be kept low. Therefore, it is possible to suppress the generation of bubbles and processing streaks, and to form a uniform coating. Therefore, the workability, particularly the workability of the casting method, is improved. A polyester plasticizer has a larger molecular weight than other plasticizers. Therefore, by using a polyester-based plasticizer, the diffusion speed of the plasticizer to other resin layers is reduced, and the plasticizer is less likely to migrate from the inside of the foam layer to the outside of the foam layer. Therefore, good oil resistance is obtained.

The phthalate ester plasticizer and polyester plasticizer in the foam layer are not particularly limited, and the same phthalate ester plasticizer and polyester plasticizer as in the non-foam layer can be used. Therefore, dialkyl phthalate (C9-C11) is preferable as the phthalate plasticizer, adipic acid polyester is preferable as the polyester plasticizer, and the number average molecular weight of the polyester plasticizer is preferably 500 to 2500 (more It is preferably 1200 to 2000), and the viscosity of the polyester plasticizer is preferably 150 to 5000 mPa s (more preferably 2000 to 5000 mPa s). . The phthalate ester plasticizer and polyester plasticizer contained in the foam layer and the phthalate ester plasticizer and polyester plasticizer contained in the non-foam layer may be the same or different.

In the foam layer, the mass ratio of the phthalate-based plasticizer and the polyester-based plasticizer (blending ratio as a solid content) is (amount of phthalate-based plasticizer):(amount of polyester-based plasticizer) = 73. :27-87:13, preferably 77:23-83:17. When the blending ratio of the phthalate plasticizer is 73% by mass or more (that is, the blending ratio of the polyester plasticizer is 27% by mass or less), the viscosity of the resin composition liquid for the foam layer can be kept low. Workability, especially workability by casting method, is improved. Good oil resistance is obtained when the blending ratio of the phthalate plasticizer is 87% by mass or less (that is, the blending ratio of the polyester plasticizer is 13% by mass or more). The mass ratio of the phthalate-based plasticizer and the polyester-based plasticizer may be the same or different between the foaming layer and the non-foaming layer.

The content of the plasticizer in the foam layer (the total content of the phthalate plasticizer and the polyester plasticizer) is 60 to 100 parts by mass, preferably 65 parts by mass, based on 100 parts by mass of the vinyl chloride resin. ~85 parts by mass. When the blending amount of the plasticizer is 60 parts by mass or more, a soft texture can be obtained. In addition, the viscosity of the resin composition liquid for the foam layer can be kept low, and workability, particularly workability by a casting method, is improved. By setting the amount of the plasticizer to be 100 parts by mass or less, the strength can be improved. Moreover, since the bleeding of the plasticizer can be suppressed, the designability can be improved. The content of the plasticizer may be the same or different between the foamed layer and the non-foamed layer.

The foam layer can be formed, for example, by adding a foaming agent to the resin composition liquid for the foam layer, and can improve the tactile feel and texture. The foaming agent is not particularly limited, and any known foaming agent can be used. From the viewpoint of foamability, it is preferable to use an organic foaming agent. Examples of organic blowing agents include azodicarbonamide (ADCA), 2,2′-azodiisobutyronitrile (AIBN), benzenesulfonylhydrazide, p-toluenesulfonylhydrazide, 4,4′-oxybis[benzenesulfonylhydrazide]. (OBSH), N,N'-dinitrosopentamethylenetetramine (DPT) and the like. These can be used individually by 1 type or in combination of 2 or more types.

The expansion ratio of the foamed layer is not particularly limited, but is preferably 2 times or less, more preferably 1.1 times or more and 2 times or less, and still more preferably 1.2 times or more and 1.7 times or less. . When the expansion ratio of the foam layer is 2 or less, independent pores are easily formed, and wear resistance, flex resistance, and peel strength can be improved.

The thickness of the foam layer is not particularly limited, and may be, for example, 150 to 370 μm, preferably 190 to 370 μm, more preferably 200 to 300 μm. When the foam layer has a thickness of 190 µm or more, a soft texture can be obtained. When the thickness of the foam layer is 370 µm or less, it is easy to adjust the diameter of the foam cells.

Conventionally known additives can be blended into the foam layer as needed within a range that does not impair its physical properties. Examples of such additives include plasticizers other than phthalate plasticizers and polyester plasticizers, thermoplastic resins and thermosetting resins other than vinyl chloride resins, heat stabilizers, fillers, pigments, Amine-resistant agents, flame retardants, conductivity-imparting agents, antistatic agents, ultraviolet absorbers, light stabilizers, antioxidants, pigment dispersants, cross-linking agents, thickeners, etc., may be used alone or in combination of two. The above can be used in combination. Specific examples and contents of the heat stabilizer and the amine-resistant agent in the foam layer are the same as those of the non-foam layer described above.

In this embodiment, when providing the foam layer, an adhesive layer may be interposed between the foam layer and the fibrous base material, or the foam layer may be directly laminated on the fibrous base material. By interposing an adhesive layer between the fibrous base material and the foam layer, the adhesion between the fibrous base material and the foam layer can be improved. The adhesive layer may be a non-foamed resin layer having no air bubbles.

The resin that constitutes the adhesive layer is not particularly limited, and resins commonly used for ordinary vinyl chloride leather can be used. Examples thereof include polyurethane resins and vinyl chloride resins.

The thickness of the adhesive layer is not particularly limited, and may be, for example, 20-200 μm or 50-150 μm.

In this embodiment, a protective layer may be further provided on the non-foamed layer. By providing a protective layer on the non-foamed layer, the physical properties of the resulting synthetic leather, particularly abrasion resistance and oil resistance, can be improved.

The protective layer preferably contains polyurethane resin. The polyurethane resin for the protective layer is not particularly limited, and examples thereof include polyether-based polyurethane resins, polyester-based polyurethane resins, and polycarbonate-based polyurethane resins. These polyurethane resins can be used singly or in combination of two or more. Among them, polycarbonate-based polyurethane resin is preferable as the polyurethane resin for the protective layer from the viewpoint of abrasion resistance.

The form of the polyurethane resin for the protective layer is not particularly limited, and may be appropriately selected according to the application. For example, it may be solvent-based or water-based, and may be one-component or two-component curable. From the viewpoint of environmental protection, the form of the polyurethane resin is preferably water-based.

　The protective layer resin composition liquid used to form the protective layer can optionally contain optional components within a range that does not impair the physical properties of the polyurethane resin. Examples of optional components include cross-linking agents, lubricants, leveling agents, thickeners, antifoaming agents, light stabilizers, conductivity imparting agents, antistatic agents, water repellent agents, oil repellent agents, antiblocking agents, antibacterial agents, and the like. are mentioned. These can be used individually by 1 type or in combination of 2 or more types.

The thickness of the protective layer is not particularly limited, and is preferably 2 to 30 μm, more preferably 5 to 20 μm, for example. Abrasion resistance can be improved if the thickness is 2 μm or more. If the thickness is 30 μm or less, a soft texture can be obtained.

In this embodiment, when providing the protective layer, an undercoat layer may be interposed between the protective layer and the non-foamed layer, or the protective layer may be laminated directly on the non-foamed layer. By interposing an undercoat layer between the surface layer and the protective layer, the physical properties of the resulting synthetic leather, particularly abrasion resistance, heat yellowing resistance and oil resistance, can be improved.

The undercoat layer preferably contains a polyurethane resin. The polyurethane resin for such an undercoat layer is not particularly limited, and examples thereof include polyether-based polyurethane resins, polyester-based polyurethane resins, and polycarbonate-based polyurethane resins. These polyurethane resins can be used singly or in combination of two or more. Among them, polyester-based polyurethane resins are preferable as the polyurethane resin for the undercoat layer from the viewpoint of heat resistance to yellowing and oil resistance.

The form of the polyurethane resin for the undercoat layer is not particularly limited, and may be appropriately selected according to the application. For example, it may be solvent-based or water-based, and may be one-component or two-component curable. From the viewpoint of environmental conservation, the polyurethane resin is preferably water-based.

　The undercoat layer resin composition liquid used to form the undercoat layer may optionally contain optional components within a range that does not impair the physical properties of the polyurethane resin. Examples of optional components include resins other than polyurethane resins (for example, acrylic resins), cross-linking agents, leveling agents, antifoaming agents, and thickening agents. These can be used individually by 1 type or in combination of 2 or more types.

The thickness of the undercoat layer is not particularly limited, and may be, for example, 1 to 20 μm or 2 to 10 μm.

Next, a method for manufacturing synthetic leather according to the present embodiment will be described. The manufacturing method is not particularly limited, and the same manufacturing method as that for conventionally known synthetic leather can be employed, and examples thereof include a calendering method and a casting method. In one embodiment, when the casting method is used, the synthetic leather of the embodiment can be manufactured by performing the following steps in order. That is, the production method is
(1) a step of applying a non-foaming layer resin composition liquid onto a release substrate to form a non-foaming layer;
(2) a step of applying a foamed layer resin composition liquid onto the non-foamed layer to form a foamed layer;
(3) a step of laminating the foam layer and the fibrous base material, and
(4) a step of peeling off the releasable substrate;
includes.

As a method for applying the resin composition liquid for the non-foaming layer onto the releasable base material, conventionally known various methods can be employed, and there is no particular limitation. Examples thereof include methods using a knife coater, comma coater, roll coater, die coater, and the like. Among them, application by a knife coater or a comma coater is preferable in that a uniform thin film layer can be formed.

The releasable base material is not particularly limited as long as it has releasability with respect to vinyl chloride resin or a base material that has undergone a releasable treatment. Examples thereof include release paper, release-treated cloth, water-repellent treated cloth, olefin sheet or film made of polyethylene resin or polypropylene resin, fluororesin sheet or film, and plastic film with release paper. The release substrate may have an uneven pattern, and by using such a release substrate, an uneven pattern such as a textured pattern is formed on the surface of the synthetic leather to impart a design property. can be done.

After applying the resin composition liquid for the non-foaming layer to the releasable base material, heat treatment is performed as necessary. Heat treatment is performed to promote gelation.

Next, the resin composition liquid for foaming layer is applied onto the non-foaming layer. As a method for applying the resin composition liquid for the foaming layer, the same method as the method for applying the resin composition liquid for the non-foaming layer can be adopted.

Next, the foam layer and the fibrous base material are laminated. Lamination methods include, for example, conventionally known methods such as a transfer method, heat fusion bonding, thermocompression bonding, and adhesion using an adhesive. When an adhesive is used, a fibrous base material may be laminated after the adhesive layer resin composition liquid is applied onto the foam layer. As a method of applying the adhesive layer resin composition liquid, the same method as the method of applying the non-foaming layer resin composition liquid can be employed.

Then, the release base material is peeled off from the non-foamed layer. A laminate of the non-foamed layer, the foamed layer, and the fibrous base is obtained by peeling off the releasable base.

When the protective layer is formed on the non-foamed layer, the protective layer may be formed on the surface of the laminate after the release substrate is peeled off as described above. The protective layer may be provided on the non-foamed layer via an undercoat layer, or may be laminated directly on the non-foamed layer. The method for applying the resin composition liquid for the undercoat layer to the surface of the non-foaming layer is not particularly limited, and the same method as the method for applying the resin composition liquid for the non-foaming layer can be used.

As a method for applying the protective layer resin composition liquid to the non-foaming layer or the undercoat layer in order to form the protective layer, the same method as the method for applying the non-foaming layer resin composition liquid can be employed. . In addition, a coating method using a device such as a spray coater, a gravure coater, a gravure direct printer, a gravure offset printer, or a screen printer can also be employed.

Next, heat treatment is performed if necessary. The heat treatment is performed to evaporate the solvent in the protective layer resin composition liquid and dry the resin. In addition, when using a cross-linking agent that causes a cross-linking reaction by heat treatment, or when using a two-component curing resin, the heat treatment is performed to promote the reaction and form a film having sufficient strength. .

Next, if necessary, the non-foamed layer (protective layer if a protective layer is formed) is formed with an uneven pattern such as a embossed pattern. As a method for forming the concave-convex pattern after peeling off the releasable base material in this manner, various conventionally known methods can be employed, and there is no particular limitation. Examples thereof include methods using embossing, vacuum embossing, welding, and pinsonic processing.

Thus, a synthetic leather according to one embodiment is obtained. However, the method for producing the synthetic leather of this embodiment is not limited to the above method.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

Each evaluation item was in accordance with the following method.

[Oil resistance]
Samples were taken at a size of 25 cm wide and 35 cm long. A sample was placed on a horizontally placed glass plate having a width of 150 mm, a length of 200 mm, and a thickness of 3 mm. Four sheets of 100% cotton gauze (“Bescare Gauze 10m 300-10M” manufactured by Yamato Factory Co., Ltd.) with a width of 20 cm and a length of 25 cm are stacked on the surface of the resin layer (non-foamed layer or protective layer) of the test piece, 60 mL of oleic acid (“15745-55” manufactured by Nacalai Tesque Co., Ltd.) was dropped through a 100% cotton gauze. A glass plate having a width of 150 mm, a length of 200 mm and a thickness of 3 mm was placed on 100% cotton gauze. This was left for 72 hours in a blower constant temperature dryer (“DRM620DD” manufactured by ADVANTEC) adjusted to 80°C. Thereafter, the glass plate and 100% cotton gauze were removed, and wiper paper (“Kimwipe S-200” manufactured by Nippon Paper Crecia Co., Ltd.) was pressed against the glass plate to remove excess oleic acid.

Two test pieces each having a width of 30 mm and a length of 120 mm were taken from the central portion of the obtained sample after the oil resistance test in the vertical direction (longitudinal direction) and the horizontal direction (width direction). The test pieces collected from the same direction are superimposed so that the resin layer surface faces inside, and the Scott type kneading tester (Scott rubbing resistance tester "CV-10N", manufactured by Daiei Kagaku Seiki Seisakusho Co., Ltd.) is gripped at intervals. Sandwiched with 30 mm. Gradually the gap between the grips was reduced so that the two specimens were separated from each other. After lightly touching the resin layer surface of the test piece, a load of 9.8 N was applied. The testing machine was moved, and the rubbing test was performed 2000 times with a load of 9.8N, a gripping distance of 30mm, and a rubbing stroke of 50mm.
(criterion)
A: No peeling or cracking of the resin layer B: At least one of peeling and cracking of the resin layer

[Abrasion resistance]
A test piece having a width of 70 mm and a length of 300 mm was taken from each of the vertical and horizontal directions, and a urethane foam having a width of 70 mm, a length of 300 mm and a thickness of 10 mm was attached to the back surface. A wire with a diameter of 4.5 mm was installed in the center of the lower surface of the urethane foam, and it was fixed to a flat abrasion tester "T-TYPE" (manufactured by Daiei Kagaku Seiki Seisakusho Co., Ltd.), and an abrading element covered with cotton cloth was placed on the wire. A wear test was performed by applying a load of 9.8 N to the friction element so that the friction element reciprocated in parallel with the wire. The friction element was reciprocated 10,000 times at a speed of 60 reciprocations/minute over a distance of 140 mm above the surface of the test piece. After the wear test, the surface condition of the test piece was observed and evaluated according to the following criteria.
(criterion)
5: No change in appearance (no cracks or breaks)
4: Slight but inconspicuous wear 3: Clear wear 2: Exposed fibrous base material 1: Exposed fibrous base material (tears observed)

[Workability]
The viscosities of the resin composition liquid for the non-foaming layer and the resin composition liquid for the foaming layer are measured with a BII type viscometer (BHII type, manufactured by Toki Sangyo Co., Ltd., rotor No. 3, 10 rpm, 23 ° C.), and are measured according to the following criteria. Judged. If it is A, it is excellent in workability.
(criterion)
A: 2000-6000 mPa·s
B: less than 2000 mPa s or more than 6000 mPa s

[Texture]
A sensory evaluation was conducted by a panelist, and judgment was made according to the following criteria. A score of B or higher is acceptable.
(criterion)
A: Soft texture B: Slightly rough texture C: Rough and hard texture

[Example 1]
<Fibrous base material>
A circular knitted fabric (polyester fiber, thickness 580 μm, mass per unit area 120 g/m ² ) was prepared as a base material.

<Prescription 1: Resin composition liquid for non-foaming layer>
・Vinyl chloride resin (polyvinyl chloride, paste resin with an average degree of polymerization of 1300, solid content 100% by mass): 100 parts by mass ・Phthalic acid ester plasticizer (dialkyl phthalate (C9-C11), solid content 100% by mass ): 65 parts by mass Polyester plasticizer (adipic acid polyester obtained by polycondensation of adipic acid and 1,3-butanediol and 1,4-butanediol, number average molecular weight 1800, viscosity (25°C) 3000 mPa s, solid content 100% by mass): 10 parts Ca-Zn-based heat stabilizer (organic acid calcium salt / organic acid zinc salt, solid content 100% by mass): 2 parts by mass Pigment (carbon black, solid content minute 100% by mass): 7 parts by mass Amine-resistant agent (sodium perchlorate, solid content 100% by mass): 0.5 parts by mass Preparation method: After mixing vinyl chloride resin and plasticizer, Ca-Zn-based A heat stabilizer, a pigment, and an anti-amine agent were added and mixed to obtain a resin composition liquid for a non-foaming layer. The viscosity (23° C.) of the resin composition liquid for the non-foaming layer was 4000 mPa·s.

<Prescription 2: Resin composition liquid for foam layer>
・Vinyl chloride resin (polyvinyl chloride, paste resin with an average degree of polymerization of 1300, solid content 100% by mass): 100 parts by mass ・Phthalic acid ester plasticizer (dialkyl phthalate (C9-C11), solid content 100% by mass ): 65 parts by mass Polyester plasticizer (adipic acid polyester obtained by polycondensation of adipic acid and 1,3-butanediol and 1,4-butanediol, number average molecular weight 1800, viscosity (25°C) 3000 mPa s, solid content 100% by mass): 10 parts Ca-Zn-based heat stabilizer (organic acid calcium salt / organic acid zinc salt, solid content 100% by mass): 2 parts by mass Pigment (carbon black, solid content minute 100% by mass): 3 parts Amine-resistant agent (sodium perchlorate, solid content 100% by mass): 1 part Organic blowing agent (azodicarbonamide, solid content 60% by mass): 1 part by mass Preparation Method: After mixing a vinyl chloride resin and a plasticizer, a Ca—Zn heat stabilizer, a pigment, an anti-amine agent, and an organic foaming agent were added and mixed to obtain a resin composition liquid for a foam layer. The viscosity (23° C.) of the resin composition liquid for the foam layer was 4000 mPa·s.

<Prescription 3: Resin composition liquid for adhesive layer>
・ Vinyl chloride resin (hydroxyl group-containing polyvinyl chloride resin obtained by copolymerizing a monomer having a hydroxyl group, average polymerization degree 1300, solid content 100% by mass): 100 parts by mass ・ Plasticizer (dialkyl phthalate (C9 to C11) , solid content 100% by mass): 100 parts Ca-Zn-based heat stabilizer (organic acid calcium salt / organic acid zinc salt, solid content 100% by mass): 2 parts by mass Flame retardant (antimony trioxide, solid content 100% by mass): 8 parts by mass Cross-linking agent (isocyanate-based cross-linking agent, solid content 100% by mass): 6.5 parts by mass Preparation method: After mixing vinyl chloride resin and plasticizer, Ca-Zn-based heat stabilization A resin composition liquid for an adhesive layer was obtained by adding and mixing an agent and a flame retardant, and then adding and mixing a cross-linking agent. The viscosity of the adhesive layer resin composition liquid was 65000 mPa·s (BII viscometer (BHII type), manufactured by Toki Sangyo Co., Ltd., rotor No. 6, 10 rpm, 23° C.).

<Prescription 4: Resin composition liquid for undercoat layer>
・Polyurethane resin (aqueous dispersion of polyester polyurethane resin, solid content 20.5% by mass): 100 parts ・Crosslinking agent (aqueous dispersion of isocyanate-based crosslinker, solid content 50% by mass): 2 parts by mass Preparation method : A cross-linking agent was added to a polyurethane resin and mixed to obtain a resin composition liquid for an undercoat layer. The viscosity of the undercoat layer resin composition liquid was 3000 mPa·s (BII type viscometer (BHII type), manufactured by Toki Sangyo Co., Ltd., rotor No. 3, 10 rpm, 23° C.).

<Prescription 5: Resin composition liquid for protective layer>
Polyurethane resin (aqueous dispersion of polycarbonate-based polyurethane resin, solid content 30% by mass): 100 parts by mass Crosslinking agent (aqueous dispersion of carbodiimide-based cross-linking agent, solid content 49.5% by mass): 2 parts by mass Lubricant (Aqueous dispersion of silicone resin, solid content: 40 parts by mass): 6 parts by mass Preparation method: After mixing a lubricant with a polyurethane resin, a cross-linking agent was added and mixed to obtain a protective layer resin composition liquid. The viscosity of the protective layer resin composition liquid was 1000 mPa·s (BII viscometer (BHII type), manufactured by Toki Sangyo Co., Ltd., rotor No. 3, 10 rpm, 23° C.).

<Production of synthetic leather>
The non-foaming layer resin composition liquid prepared according to the above recipe 1 is coated on a flat release paper (trade name “VX-12”, manufactured by Lintec Corporation) with a comma coater so that the thickness is 160 μm. and heat-treated in a dryer at 180° C. for 2 minutes and 30 seconds to form a non-foaming layer.

Next, the foamed layer resin composition liquid prepared according to Formulation 2 above is coated on the non-foamed layer formed on the release paper with a comma coater so that the coating thickness becomes 140 μm in a sheet form, and dried. A foam layer was formed by heat-treating at 200° C. for 2 minutes and 30 seconds using a machine.

Next, the adhesive layer resin composition liquid prepared according to Formulation 3 above was coated on the foam layer in a sheet form with a knife coater so that the coating thickness was 90 μm. After that, the fibrous base material was superimposed and treated in a dryer at 180° C. for 2 minutes and 30 seconds to form an adhesive layer and bond with the fibrous base material. After that, the release paper was peeled off to obtain a laminate composed of a non-foamed layer, a foamed layer, an adhesive layer, and a fibrous base material.

Next, the undercoat layer resin composition liquid prepared according to Formulation 4 above was coated on the surface of the non-foamed layer after peeling off the release paper in a sheet form with a gravure coater so that the coating thickness was 12 μm. and heat-treated at 130° C. for 2 minutes in a dryer to form an undercoat layer.

Next, the protective layer resin composition solution prepared according to Formulation 5 above was applied to the surface of the undercoat layer in the form of a sheet using a gravure coater so that the coating thickness was 15 μm. A heat treatment was performed for 1 minute to form a protective layer.

Next, after preheating the obtained laminate at 170°C for 15 seconds with an infrared heater, a grain pattern was formed on the front surface of the protective layer with a vacuum embossing machine to obtain the synthetic leather of Example 1. The non-foamed layer had a thickness of 160 μm, the foamed layer had an expansion ratio of 1.5, and the foamed layer had a thickness of 210 μm.

The thickness of each resin layer is obtained by observing the vertical cross section of the synthetic leather with a microscope (manufactured by Keyence Corporation, Digital HF Microscope VH-8000), measuring the thickness at any 10 points, and averaging these It is a value obtained by calculating the value.

The expansion ratio of the foam layer was determined by coating the resin composition liquid for the foam layer on release paper with a comma coater in the form of a sheet to a coating thickness of 140 μm, followed by drying at 200° C. for 2 minutes and 30 seconds. The thickness of the obtained foamed sheet was measured and calculated by the following formula.
Expansion ratio (times)=film thickness of foam sheet/{coating thickness (140 μm)×solid content of resin composition liquid for foam layer}

[Examples 2 to 14, Comparative Examples 1 to 6]
A synthetic leather was obtained in the same manner as in Example 1, except that the formulation of the resin composition for each resin layer was changed as shown in Tables 1 to 4. "%" for the solid content in Tables 1 to 4 is mass%. Regarding the polyester plasticizer, the viscosity and number average molecular weight of the adipic acid-based polyester in Tables 1-4 are as shown in Tables 1-4. Specifically, the adipic acid-based polyesters in Tables 1 to 4 are all obtained by polycondensing adipic acid with 1,3-butanediol and 1,4-butanediol. In Example 7, an adipic acid-based polyester having a number average molecular weight of 800 and a viscosity (25° C.) of 200 mPa·s was used. In Example 8, an adipic acid-based polyester having a number average molecular weight of 2,200 and a viscosity (25° C.) of 5,000 mPa·s was used. The adipic acid-based polyesters used in other examples and comparative examples are the same as in Example 1, as described above.

The evaluation results for Examples 1-14 and Comparative Examples 1-6 are shown in Tables 1-4. In Comparative Example 1, the mass ratio of the phthalate ester plasticizer and the polyester plasticizer contained in the non-foamed layer and the foamed layer was 93:7, and the amount of the phthalate ester plasticizer was large. was inferior. In Comparative Examples 3 to 5, the non-foamed layer and/or the foamed layer contained only the phthalate ester plasticizer, so the oil resistance was poor. In Comparative Example 2, the mass ratio of the phthalate plasticizer and the polyester plasticizer contained in the non-foamed layer and the foamed layer was 67:33, and the content of the polyester plasticizer was large, so oil resistance was improved. Although it was excellent, foam entrapment occurred and the workability was poor. In Comparative Example 6, the content of the plasticizer was small and the workability was poor. In contrast, Examples 1 to 14 were excellent in oil resistance and workability.

The present invention includes embodiments shown below.
[1] A synthetic leather comprising, in this order, a fibrous base material, a foamed layer containing a vinyl chloride resin and a plasticizer, and a non-foamed layer containing a vinyl chloride resin and a plasticizer, In each of the foamed layer and the non-foamed layer, the content of the plasticizer is 60 to 100 parts by mass with respect to 100 parts by mass of the vinyl chloride resin, and the plasticizer is a phthalate plasticizer and a polyester synthetic leather, wherein the mass ratio of the phthalate plasticizer and the polyester plasticizer is 73:27 to 87:13 (preferably 77:23 to 83:17).
[2] The synthetic leather according to [1], wherein the polyester plasticizer in the foamed layer and the non-foamed layer has a number average molecular weight of 500 to 2500 (preferably 1200 to 2000).
[3] According to [1] or [2], wherein the polyester plasticizer in the foamed layer and the non-foamed layer has a viscosity at 25° C. of 150 to 5000 mPa·s (preferably 2000 to 5000 mPa·s). synthetic leather.
[4] The polyester-based plasticizer in the foamed layer and the non-foamed layer is at least one selected from the group consisting of adipic acid-based polyesters, sebacic acid-based polyesters, and phthalic acid-based polyesters, preferably adipic acid-based plasticizers. The synthetic leather according to any one of [1] to [3], which is a polyester plasticizer.
[5] The phthalate ester plasticizer in the foam layer and the non-foam layer is dibutyl phthalate, dioctyl phthalate, dinonyl phthalate, diisononyl phthalate, diisodecyl phthalate, ditridecyl phthalate, diundecyl phthalate, phthalate. Any of [1] to [4], which is at least one selected from the group consisting of benzyl butyl acid, nonylundecyl phthalate, and dialkyl phthalate (C9-C11), preferably dialkyl phthalate (C9-C11) 1. Synthetic leather according to item 1.
[6] The synthetic leather according to any one of [1] to [5], wherein the non-foamed layer has a thickness of 100 to 300 μm (preferably 130 to 250 μm).
[7] The foamed layer and the non-foamed layer each further contain a heat stabilizer (preferably a calcium salt of an organic acid and/or a zinc salt of an organic acid), and preferably the content of the heat stabilizer is the vinyl chloride resin. The synthetic leather according to any one of [1] to [6], which is 0.1 to 10 parts by mass (preferably 0.5 to 5 parts by mass) per 100 parts by mass.
[8] The foamed layer and the non-foamed layer each further contain an amine-resistant agent (preferably perchlorate), and preferably the content of the amine-resistant agent is 0 with respect to 100 parts by mass of the vinyl chloride resin. 05 to 5 parts by mass (preferably 0.1 to 2 parts by mass), the synthetic leather according to any one of [1] to [7].
[9] The synthetic leather according to any one of [1] to [8], wherein the foam layer is formed by adding a foaming agent (preferably an organic foaming agent) to the foam layer resin composition liquid. .
[10] The foaming layer of [1] to [9], wherein the expansion ratio of the foam layer is 2 times or less (preferably 1.1 times or more and 2 times or less, more preferably 1.2 times or more and 1.7 times or less). The synthetic leather according to any one of

items

1 and 2.
[11] The synthetic leather according to any one of [1] to [10], wherein the foam layer has a thickness of 150 to 370 μm (preferably 190 to 370 μm, more preferably 200 to 300 μm).
[12] The synthesis according to any one of [1] to [11], further comprising an adhesive layer containing a polyurethane resin and/or a vinyl chloride resin between the fibrous base material and the foam layer. leather.
[13] The synthetic leather according to any one of [1] to [12], further comprising a protective layer containing a polyurethane resin (preferably a polycarbonate-based polyurethane resin) on the non-foamed layer.
[14] The synthetic leather according to [13], wherein the protective layer has a thickness of 2 to 30 μm (preferably 5 to 20 μm).
[15] The synthetic leather according to [13] or [14], further comprising an undercoat layer containing a polyurethane resin (preferably a polyester polyurethane resin) between the non-foamed layer and the protective layer.
[16] The non-foamed layer is a resin layer formed by applying a non-foamed layer resin composition liquid onto a releasable substrate, and the foamed layer is formed on the releasable substrate. a resin layer formed by applying a resin composition liquid for a foamed layer onto the non-foamed layer, wherein the resin composition liquid for the non-foamed layer and the resin composition liquid for the foamed layer are each composed of a vinyl chloride resin; A plasticizer containing a phthalate plasticizer and a polyester plasticizer in a mass ratio of 73:27 to 87:13, and the content of the plasticizer is 60 to 100 with respect to 100 parts by mass of the vinyl chloride resin. The synthetic leather according to any one of [1] to [15], which is parts by mass.
[17] The synthetic leather according to any one of [1] to [16], which has an uneven pattern (preferably a embossed pattern) on the front side.

It should be noted that the various numerical ranges described in the specification can be arbitrarily combined with their upper and lower limits, and all combinations thereof are described in this specification as preferred numerical ranges. In addition, the description of a numerical range of "X to Y" means X or more and Y or less unless otherwise specified.

DESCRIPTION OF

SYMBOLS

1, 10, 100... Synthetic leather, 2... Fiber base material, 3... Foaming layer, 4... Non-foaming layer, 5... Adhesive layer, 6... Protective layer, 7... Undercoat layer

Claims

A synthetic leather containing, in this order, a fibrous base material, a foamed layer containing a vinyl chloride resin and a plasticizer, and a non-foamed layer containing a vinyl chloride resin and a plasticizer,
In each of the foamed layer and the non-foamed layer, the content of the plasticizer is 60 to 100 parts by mass with respect to 100 parts by mass of the vinyl chloride resin, and the plasticizer is a phthalate plasticizer. A synthetic leather comprising a polyester plasticizer and a mass ratio of the phthalate plasticizer and the polyester plasticizer of 73:27 to 87:13.
The synthetic leather according to claim 1, wherein the polyester plasticizer in the foamed layer and the non-foamed layer has a number average molecular weight of 500 to 2,500.
The synthetic leather according to claim 1 or 2, wherein the polyester plasticizer in the foamed layer and the non-foamed layer has a viscosity at 25°C of 150 to 5000 mPa·s.
The synthetic leather according to any one of claims 1 to 3, wherein the polyester-based plasticizer in the foamed layer and the non-foamed layer is an adipic acid-based polyester plasticizer.
The synthetic leather according to any one of claims 1 to 4, wherein the phthalate plasticizer in the foam layer and the non-foam layer is dialkyl phthalate (C9-C11).
The synthetic leather according to any one of claims 1 to 5, further comprising an adhesive layer containing a polyurethane resin and/or a vinyl chloride resin between the fibrous base material and the foam layer.
The synthetic leather according to any one of claims 1 to 6, further comprising a protective layer containing a polyurethane resin on the non-foamed layer.
The synthetic leather according to claim 7, further comprising an undercoat layer containing a polyurethane resin between the non-foamed layer and the protective layer.
The non-foaming layer is a resin layer formed by applying a resin composition liquid for a non-foaming layer onto a releasable substrate,
The foamed layer is a resin layer formed by applying a resin composition liquid for a foamed layer onto the non-foamed layer formed on the release substrate,
The resin composition liquid for the non-foaming layer and the resin composition liquid for the foaming layer each contain a vinyl chloride resin, a phthalate plasticizer, and a polyester plasticizer in a mass ratio of 73:27 to 87:13. The synthetic leather according to any one of claims 1 to 8, wherein the content of the plasticizer is 60 to 100 parts by mass with respect to 100 parts by mass of the vinyl chloride resin.