Synthetic leather

Abstract

We provide synthetic leather that is easy to recycle and also boasts excellent durability and flexibility. [Solution] A synthetic leather comprising a base layer and a surface layer, wherein the base layer contains a polyester resin and the surface layer contains a thermoplastic polyester elastomer.

Description

Technical Field

[0001] The present invention relates to synthetic leather excellent in recyclability, durability, and flexibility.

Background Art

[0002] Conventionally, synthetic leather has been widely used in vehicle applications as automotive interior materials such as, for example, ceiling skin materials, door trim materials, instrument panel materials, and car seat skin materials for automobiles. As synthetic leather, vinyl leather, which was excellent in leather-like appearance, price, abrasion resistance, formability, etc., was widely used in the past. However, since vinyl leather contains polyvinyl chloride as a constituent component, there is concern about the generation of dioxins during incineration after disposal, and its use is being restricted.

[0003] As synthetic leather to replace vinyl leather, various materials such as those obtained by impregnating or laminating a polyurethane resin on a fibrous base material have been developed. As synthetic leather obtained by impregnating or laminating a polyurethane resin on a fibrous base material, the synthetic leathers described in Patent Documents 1 to 3 are known.

[0004] Patent Document 1 describes synthetic leather that has high flame retardancy due to the inclusion of a flame retardant in the adhesive layer. In this synthetic leather, a surface layer containing polyurethane is formed on a polyester tricot knitted fabric used as a base layer via a polyurethane adhesive. Patent Document 2 describes a surface material that has high moisture permeability and breathability and excellent appearance by providing the surface material with multiple ventilation holes that penetrate in the thickness direction. In this surface material, a surface layer containing polyurethane is formed on a base fabric containing polyester fibers via an adhesive layer containing polyurethane. Patent Document 3 describes synthetic leather having a layer made of synthetic resin and a fibrous fabric base material. This synthetic leather ensures mechanical strength despite the high concentration of additives that are solid at room temperature in the layer made of synthetic resin. An example in Patent Document 3 describes synthetic leather in which a surface layer containing polycarbonate polyurethane resin, a reinforcing layer containing polycarbonate polyurethane resin, an adhesive layer containing polycarbonate polyurethane resin, and a polyester fabric (base material) are laminated together. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Patent No. 5731086 [Patent Document 2] Japanese Patent Publication No. 2016-129994 [Patent Document 3] Japanese Patent Publication No. 2022-72684 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The synthetic leathers described in Patent Documents 1 to 3 use nonwoven or woven fabrics made of polyester resins, such as polyethylene terephthalate, for the base layer, but the surface layer uses polyurethane resin, polyamide resin, polyacrylate resin, vinyl acetate resin, polyacrylonitrile resin, etc., either alone or in combination of two or more, and a polyurethane adhesive is used as the adhesive layer to bond the surface layer and the base layer. However, because a variety of resins are used, the materials are usually incinerated after use, and it is currently difficult to recover and reuse them.

[0007] Incidentally, synthetic leather is required to have durability such as resistance to delamination between the base layer and the surface layer, and flexibility such as resistance to cracking even when repeatedly bent. However, no synthetic leather was known that was excellent in durability and flexibility, as well as recyclability.

[0008] The objective of this invention is to provide synthetic leather that is easily recyclable and also has excellent durability and flexibility. [Means for solving the problem]

[0009] The present invention is as follows: [1] Synthetic leather comprising a base layer and a surface layer, wherein the base layer comprises a polyester resin and the surface layer comprises a thermoplastic polyester elastomer-containing composition. [2] The synthetic leather according to [1], wherein the thermoplastic polyester elastomer is composed of a hard segment and a soft segment bonded together, the hard segment is made of a polyester comprising an aromatic dicarboxylic acid and an aliphatic diol and / or an alicyclic diol, the soft segment comprises at least one selected from aliphatic polyether, aliphatic polyester and aliphatic polycarbonate, and the thermoplastic polyester elastomer-containing composition contains 30 to 90% by mass of the soft segment with respect to 100% by mass of the thermoplastic polyester elastomer. [3] The synthetic leather according to [1] or [2], wherein the thermoplastic polyester elastomer-containing composition has a glass transition temperature (Tg) of -30°C or lower. [4] The thermoplastic polyester elastomer-containing composition is a synthetic leather according to any one of [1] to [3], wherein the acid value is 60 eq / t or less. [5] The thermoplastic polyester elastomer-containing composition is a synthetic leather according to any one of [1] to [4], wherein the reduced viscosity is 1.0 to 3.5 dl / g. [6] The synthetic leather according to any one of [1] to [5], wherein the thermoplastic polyester elastomer-containing composition contains 0.01 to 3.0 parts by mass of a weather-resistant agent per 100 parts by mass of the thermoplastic polyester elastomer. [7] The synthetic leather according to any one of [1] to [6], wherein the thermoplastic polyester elastomer-containing composition contains 0.1 to 5.0 parts by mass of a lubricant per 100 parts by mass of the thermoplastic polyester elastomer. [8] The synthetic leather according to any one of [1] to [7], wherein the thermoplastic polyester elastomer-containing composition contains 0.1 to 10 parts by mass of an abrasion resistance improver per 100 parts by mass of the thermoplastic polyester elastomer. [9] A synthetic leather according to any one of [1] to [8], having an adhesive layer containing a polyester resin between the base material layer and the surface layer.

[10] The synthetic leather according to [9], wherein the adhesive layer contains a resin having a glass transition temperature (Tg) of -10°C or lower.

[11] The synthetic leather according to [9] or

[10] , wherein the polyester resin constituting the adhesive layer is amorphous. [Effects of the Invention]

[0010] The synthetic leather according to the present invention comprises a base layer and a surface layer, the base layer containing a polyester resin, and the surface layer containing a thermoplastic polyester elastomer-containing composition. Because both the base layer and the surface layer are polyester-based, it exhibits excellent recyclability. Furthermore, because the surface layer contains thermoplastic polyester elastomer, it achieves a synthetic leather that is excellent in both durability and flexibility. [Modes for carrying out the invention]

[0011] The embodiments of the synthetic leather according to the present invention will be described in detail below. The synthetic leather in the embodiments comprises a base layer and a surface layer, the base layer comprises a polyester resin, and the surface layer comprises a thermoplastic polyester elastomer-containing composition.

[0012] 1.Base material layer The base layer contains a polyester resin.

[0013] The base layer may be a nonwoven fabric or a woven or knitted fabric, and may be a nonwoven fabric or woven or knitted fabric composed of fibers containing a polyester resin.

[0014] The polyester resin constituting the base layer is not particularly limited as long as it has fiber-forming ability. For example, thermoplastic resins such as polyethylene terephthalate, polytrimethylene terephthalate, and polybutylene terephthalate, as well as polyester resins such as low-melting-point polyesters mainly composed of these and further using isophthalic acid as a copolymer component, or mixtures or copolymers thereof can be used. The synthetic fibers obtained from the thermoplastic resin may be single-component systems, or multi-component systems such as core-sheath type, eccentric core-sheath type, parallel type, or sea-island type. The cross-sectional shape of the fibers is not particularly limited.

[0015] The polyester resin-containing fiber may be, for example, a blend of fibers made from multiple resins, such as copolymerized polyester.

[0016] For fibers containing polyester-based resins, in addition to the flame retardants described later as required, additives such as matting agents, pigments, antioxidants, ultraviolet absorbers, light stabilizers, crystal nucleating agents, and acaricides may be contained or impregnated. In particular, for flame retardants, in addition to adding them to the skin layer as described later, they can also be contained or impregnated in the base material layer to further improve the flame retardancy of the synthetic leather. However, from the perspective of recyclability, it is preferable that the addition amount of the flame retardant is as small as possible.

[0017] The base material layer may be a single layer or may have a multilayer structure. When the base material layer has a multilayer structure, different types of non-woven fabrics may be laminated, different types of woven or knitted fabrics may be laminated, or non-woven fabrics and woven or knitted fabrics may be laminated.

[0018] The base material layer may be raised, and the raising may be on only one side or both sides of the base material layer. By raising the side of the base material layer on the skin layer side, the adhesion with the skin layer is increased, and the peeling strength can be improved. By raising the side of the base material layer opposite to the skin layer side, the volume feeling of the synthetic leather can be improved.

[0019] The basis weight of the base material layer is not particularly limited, but for example, it may be 30 to 500 g / m 2 It may also be suitable.

[0020] When using a woven or knitted fabric as the base material layer, the weaving method of the fabric or the knitting method of the knitted fabric is not particularly limited. For example, woven or knitted fabrics are thin and lightweight, and in the case of fabrics, they are excellent in strength and wear resistance, and in the case of knitted fabrics, they have the advantages of extensibility and a soft texture.

[0021] When using a non-woven fabric as the base material layer, the non-woven fabric may be either a short fiber non-woven fabric or a long fiber non-woven fabric, but long fiber non-woven fabrics are preferred from the perspective of ensuring better mechanical properties.

[0022] The method for manufacturing nonwoven fabrics is not particularly limited, but examples include the spunbond method and the meltblown method for long-fiber nonwoven fabrics, and the carding method and the air-lay method for short-fiber nonwoven fabrics. As for the nonwoven fabric, those having a two-layer structure in which the fiber structure constituting the upper layer and the fiber structure constituting the lower layer are laminated by mechanical entanglement are particularly preferred.

[0023] 2. Epidermal layer The epidermal layer contains a thermoplastic polyester elastomer-containing composition.

[0024] The thermoplastic polyester elastomer may have hard segments and soft segments bonded together.

[0025] The hard segment may be composed of polyester, preferably a polyester comprising an aromatic dicarboxylic acid and an aliphatic diol and / or alicyclic diol, and more preferably a polyester comprising an aromatic dicarboxylic acid and an aliphatic diol.

[0026] As the aromatic dicarboxylic acid, any known aromatic dicarboxylic acid can be used and is not particularly limited, but examples include terephthalic acid, dimethyl terephthalate, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, isophthalic acid, and 5-sodium sulfisoisophthalic acid. Among the isomers of naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid is preferred.

[0027] The aromatic dicarboxylic acid content is preferably 70 mol% or more, and more preferably 80 mol% or more, of the total dicarboxylic acids constituting the polyester of the hard segment.

[0028] The hard segment may contain dicarboxylic acids other than aromatic dicarboxylic acids, such as alicyclic dicarboxylic acids and aliphatic dicarboxylic acids. Examples of alicyclic dicarboxylic acids include cyclohexanedicarboxylic acid and tetrahydrophthalic anhydride. Examples of aliphatic dicarboxylic acids include succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, dimer acid, and hydrogenated dimer acid. These may be included in a range that does not significantly lower the melting point of the epidermal layer, and their amount is preferably 30 mol% or less, and more preferably 20 mol% or less, relative to the total acid components.

[0029] As the aliphatic diol or alicyclic diol, known aliphatic diols or alicyclic diols can be used and are not particularly limited, but alkylene glycols having 2 to 8 carbon atoms are preferred. Examples of aliphatic diols include ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, and 1,6-hexanediol. Among these, ethylene glycol or 1,4-butanediol are preferred. Examples of alicyclic diols include 1,4-cyclohexanedimethanol.

[0030] As components constituting the hard segment polyester, butylene terephthalate units (units consisting of terephthalic acid and 1,4-butanediol) and / or butylene naphthalate units (units consisting of 2,6-naphthalenedicarboxylic acid and 1,4-butanediol) are preferred in terms of physical properties, moldability, and cost performance.

[0031] The soft segment preferably contains at least one selected from aliphatic polyethers, aliphatic polyesters, and aliphatic polycarbonates, with aliphatic polyethers being more preferred. These components may be used individually or in combination of two or more.

[0032] Examples of aliphatic polyethers include poly(ethylene oxide) glycol, poly(propylene oxide) glycol, poly(tetramethylene oxide) glycol, poly(hexamethylene oxide) glycol, poly(trimethylene oxide) glycol, copolymers of ethylene oxide and propylene oxide, ethylene oxide adducts of poly(propylene oxide) glycol, and copolymers of ethylene oxide and tetrahydrofuran. Among these, poly(tetramethylene oxide) glycol and ethylene oxide adducts of poly(propylene oxide) glycol are preferred from the viewpoint of elastic properties.

[0033] Examples of aliphatic polyesters include poly(ε-caprolactone), polyenanthractone, polycapryloractone, and polybutylene adipate. Among these, poly(ε-caprolactone) and polybutylene adipate are preferred in terms of elastic properties.

[0034] As for the aliphatic polycarbonate, for example, one consisting of aliphatic diol residues having 2 to 12 carbon atoms is preferred. Examples of aliphatic diols include ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 2,2-dimethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 1,9-nonanediol, and 2-methyl-1,8-octanediol. Among these, aliphatic diols having 5 to 12 carbon atoms are preferred in terms of the flexibility and low-temperature properties of the thermoplastic polyester elastomer.

[0035] For aliphatic polycarbonate diols that constitute soft segments and have good low-temperature properties, those with a low melting point (e.g., 70°C or below) and a low glass transition temperature are preferred. Generally, aliphatic polycarbonate diols made of 1,6-hexanediol, which are used to form soft segments of thermoplastic polyester elastomers, have a low glass transition temperature of around -60°C and a melting point of around 50°C, thus exhibiting good low-temperature properties. In addition, aliphatic polycarbonate diols obtained by copolymerizing an appropriate amount of 3-methyl-1,5-pentanediol with the above aliphatic polycarbonate diol have a slightly higher glass transition temperature than the original aliphatic polycarbonate diol, but their melting point is lower or they become amorphous, thus corresponding to aliphatic polycarbonate diols with good low-temperature properties. Furthermore, for example, an aliphatic polycarbonate diol composed of 1,9-nonanediol and 2-methyl-1,8-octanediol has a sufficiently low melting point of around 30°C and a glass transition temperature of around -70°C, making it an aliphatic polycarbonate diol with good low-temperature properties.

[0036] The thermoplastic polyester elastomer is preferably a copolymer mainly composed of terephthalic acid, 1,4-butanediol, and poly(tetramethylene oxide) glycol. Among the dicarboxylic acid components constituting the thermoplastic polyester elastomer, terephthalic acid is preferably 40 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, and particularly preferably 90 mol% or more. Among the glycol components constituting the thermoplastic polyester elastomer, the total of 1,4-butanediol and poly(tetramethylene oxide) glycol is preferably 40 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, and particularly preferably 90 mol% or more.

[0037] The number-average molecular weight of poly(tetramethylene oxide) glycol may be between 500 and 4000, preferably between 800 and 3000, and more preferably between 1000 and 2500. If the number-average molecular weight is less than 500, it may be difficult to exhibit elastomer properties. On the other hand, if the number-average molecular weight exceeds 4000, the compatibility with hard segments decreases, and block copolymerization may become difficult.

[0038] The thermoplastic polyester elastomer-containing composition may contain 30 to 90% by mass of soft segments per 100% by mass of thermoplastic polyester elastomer, preferably 45 to 90% by mass, and more preferably 60 to 90% by mass. If the soft segment content falls below 30% by mass, low-temperature properties tend to be impaired. Also, hardness tends to increase, making it difficult to obtain a soft touch on the surface layer. If the soft segment content exceeds 90% by mass, oil resistance and solvent resistance tend to be inferior.

[0039] The thermoplastic polyester elastomer-containing composition may have a glass transition temperature (Tg) of -30°C or lower, preferably -40°C or lower, and more preferably -50°C or lower. If the Tg of the thermoplastic polyester elastomer-containing composition exceeds -30°C, the surface layer hardens, impairing flexibility and other properties, resulting in a poor texture as synthetic leather. In particular, bending at low temperatures makes cracking and other phenomena more likely.

[0040] To achieve a Tg of -30°C or lower for a thermoplastic polyester elastomer-containing composition, it is preferable to use an aliphatic polyether as a copolymer component, and more preferably to include poly(tetramethylene oxide) glycol.

[0041] Thermoplastic polyester elastomers can be produced by known methods. For example, a method in which a lower alcohol diester of a dicarboxylic acid, an excess amount of low molecular weight glycol, and a soft segment component are transesterified in the presence of a catalyst, and the resulting reaction product is polycondensed; a method in which a dicarboxylic acid, an excess amount of glycol, and a soft segment component are esterified in the presence of a catalyst, and the resulting reaction product is polycondensed; a method in which a hard segment polyester is prepared in advance, and a soft segment component is added to it and randomized by a transesterification reaction; a method in which hard segments and soft segments are linked with a chain linker; and, when poly(ε-caprolactone) is used as the soft segment, a method in which an ε-caprolactone monomer is added to the hard segment.

[0042] When an aromatic polyester suitable for constituting the hard segment is manufactured in advance and then copolymerized with the soft segment, the aromatic polyester can be easily obtained according to the usual method for manufacturing polyester. The number-average molecular weight of the aromatic polyester may be between 10,000 and 40,000.

[0043] The thermoplastic polyester elastomer-containing composition may have a reduced viscosity of 1.0 to 3.5 dl / g, preferably 1.5 to 3.0 dl / g, and more preferably 1.8 to 2.8 dl / g. If the reduced viscosity of the thermoplastic polyester elastomer-containing composition is below 1.0 dl / g, the fatigue resistance of the thermoplastic polyester elastomer may decrease. On the other hand, if the reduced viscosity of the thermoplastic polyester elastomer-containing composition exceeds 3.5 dl / g, melt fracture may occur during melt extrusion molding, resulting in a defective appearance.

[0044] The thermoplastic polyester elastomer-containing composition may have an acid value of 60 eq / t or less, preferably 50 eq / t or less, and more preferably 40 eq / t or less. If the acid value of the thermoplastic polyester elastomer-containing composition exceeds 60 eq / t, the hydrolysis resistance may deteriorate. The lower limit of the acid value of the thermoplastic polyester elastomer-containing composition is not particularly limited, but for example, it may be 10 eq / t or more.

[0045] The thermoplastic polyester elastomer-containing composition may contain additives. The type of additive is not particularly limited, and additives commonly used when molding thermoplastic resins can be used. Examples of additives include: weathering agents; lubricants; abrasion resistance improvers; thickeners such as known epoxy compounds, polycarbodiimides, and oxazolines; hindered phenol, sulfur, phosphorus, and amine antioxidants; fillers; flame retardants; flame retardant aids; mold release agents; antistatic agents; molecular modifiers such as peroxides; metal deactivators; organic or inorganic nucleating agents; neutralizing agents; antacids; antibacterial agents; fluorescent whitening agents; organic or inorganic pigments; organic or inorganic phosphorus compounds used for the purpose of imparting flame retardancy or thermal stability; and so on. Among these, it is preferable to contain at least one selected from the group consisting of weathering agents, lubricants, and abrasion resistance improvers.

[0046] The amount of additives contained in the thermoplastic polyester elastomer-containing composition should be within a range that does not impair the physical properties of the surface layer, and should be the same as the amount used when molding ordinary thermoplastic resins.

[0047] (Weather-resistant agent) The thermoplastic polyester elastomer-containing composition may also contain a weather-resistant agent. A weather-resistant agent refers to a compound that has the ability to suppress the degradation of the resin composition due to light, including not only sunlight but also incandescent light, etc. It is mainly classified into two types of compounds: ultraviolet absorbers (UVA) that convert light energy into harmless thermal energy, and hindered amine-based light stabilizers (HALS) that capture radicals generated by photo-oxidation.

[0048] Examples of ultraviolet absorbers (UVA) include benzophenone-based, benzotriazole-based, benzoate-based, triazine-based, cyanoacrylate-based, salicylate-based, oxanilide-based, and nickel-based compounds. Examples of benzophenone-based compounds include 2,2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-i-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, and 2-hydroxy-4-octadecyloxybenzophenone. Examples of benzotriazole derivatives include 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-t-amylphenyl)benzotriazole, 2-[2'-hydroxy-3',5'-bis(α,α-dimethylbenzylphenyl)benzotriazole, 2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl)-5-chlorobenzotriazole, and 2-(2'-hydroxy-3',5'-di-t-butylphenyl Examples include (L)-5-chlorobenzotriazole, 2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]-2H-benzotriazole, 2-[2'-hydrooxy-5'-methyl-3'-(3'',4'',5'',6''-tetrahydrophthalimidomethyl)phenyl]benzotriazole, bis(5-benzoyl-4-hydroxy-2-methoxyphenyl)methane, and 2-(2'-hydroxy-5'-t-octylphenyl)benzotriazole. Benzoate derivatives include, for example, 2,4-di-t-butylphenyl-3,5-di-t-butyl-4-hydroxybenzoate and 2,5-bis-[5'-t-butylbenzoxazolyl-(2)]-thiophene. Examples of triazine compounds include 2,4,6-tris(4-butoxy-2-hydroxyphenyl)-1,3,5-triazine and 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-(hexyloxy)phenol. Examples of salicylate compounds include pt-butylphenyl salicylate and phenyl salicylate.Examples of oxanilide-based compounds include a mixture of 85-90% 2-ethoxy-5-t-butyl-2'-ethyl oxalic acid bis-anilide and 10-15% 2-ethoxy-5-t-butyl-2'-ethyl-4'-t-butyl oxalic acid bis-anilide, and 2-ethoxy-2'-ethyl oxazalic acid bis-anilide. Examples of nickel-based compounds include bis(3,5-di-t-butyl-4-hydroxybenzyl phosphate monoethyl ester) nickel salt.

[0049] Ultraviolet light can be further classified into, for example, short-wavelength ultraviolet (UV-C) below 290 nm, medium-wavelength ultraviolet (UV-B) between 290 and 320 nm, and long-wavelength ultraviolet (UV-A) between 320 and 400 nm. Since the UV-A region affects the photodegradation of all organic materials, ultraviolet absorption performance in the UV-A region is required, not just the conventional UV-B region.

[0050] Examples of hindered amine light stabilizers (HALS) include 2,2,6,6-tetramethyl-4-piperidyl stearate, 1,2,2,6,6-pentamethyl-4-piperidyl stearate, 2,2,6,6-tetramethyl-4-piperidyl benzoate, bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, bis(1-octoxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate, and tetrakis(2,2,6,6-tetramethyl-4- Piperidyl)-1,2,3,4-butanetetracarboxylate, tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)-1,2,3,4-butanetetracarboxylate, bis(2,2,6,6-tetramethyl-4-piperidyl)·di(tridecyl)-1,2,3,4-butanetetracarboxylate, bis(1,2,2,6,6-pentamethyl-4-piperidyl)·di(tridecyl)-1,2,3,4-butanetetracarboxylate, bis(1,2,2,4,4-pentamethyl-4-piperidyl)-2-butyl-2-(3,5- Di-t-butyl-4-hydroxybenzyl)malonate, 1-(2-hydroxyethyl)-2,2,6,6-tetramethyl-4-piperidinol / diethyl succinate polycondensate, 1,6-bis(2,2,6,6-tetramethyl-4-piperidylamino)hexane / 2,4-dichloro-6-morpholino-s-triazine polycondensate, 1,6-bis(2,2,6,6-tetramethyl-4-piperidylamino)hexane / 2,4-dichloro-6-tertiaryoctylamino-s-triazine polycondensate, 1,5,8,12-tetrakis[2,4-bis(N-butyl-N -(2,2,6,6-tetramethyl-4-piperidyl)amino)-s-triazine-6-yl]-1,5,8,12-tetraazadodecane, 1,5,8,12-tetrakis[2,4-bis(N-butyl-N-(1,2,2,6,6-pentamethyl-4-piperidyl)amino)-s-triazine-6-yl]-1,5,8-12-tetraazadodecane, 1,6,11-tris[2,4-bis(N-butyl-N-(2,2,6,6-tetramethyl-4-piperidyl)amino)-s-triazine-6-yl]aminoundecane, 1,6,11-tris[2,Examples of hindered amine compounds include 4-bis(N-butyl-N-(1,2,2,6,6-pentamethyl-4-piperidyl)amino)-s-triazine-6-yl]aminoundecane.

[0051] When a weather-resistant agent is included in a thermoplastic polyester elastomer-containing composition, the amount of the weather-resistant agent may be 0.01 to 3.0 parts by mass per 100 parts by mass of thermoplastic polyester elastomer, preferably 0.05 to 2.0 parts by mass, and more preferably 0.1 to 1.0 parts by mass. If the amount of the weather-resistant agent is less than 0.01 parts by mass, the blending ratio to the thermoplastic polyester elastomer-containing composition will be low, and the performance may not be fully exhibited. On the other hand, if the amount of the weather-resistant agent exceeds 3.0 parts by mass, the weather-resistant agent may become an impurity during recycling, reducing recyclability. In addition, if synthetic leather is used for a long period of time, bleeding may occur on the surface of the synthetic leather.

[0052] From the viewpoint of long-term retention, it is preferable to use a weather-resistant agent that has high compatibility with thermoplastic polyester elastomers. If the compatibility with thermoplastic polyester elastomers is low, it may bleed out onto the surface of the epidermal layer, resulting in an undesirable appearance of the synthetic leather.

[0053] From the viewpoint of long-term retention, the molecular weight of the weather-resistant agent is preferably 200 or more, more preferably 300 or more, and even more preferably 400 or more. If the molecular weight of the weather-resistant agent is less than 200, it tends to migrate to the surface of the epidermal layer, which may cause defects in the appearance of the synthetic leather.

[0054] From the viewpoint of ease of handling during processing, the melting point of the weather-resistant agent is preferably 20°C or higher, more preferably 30°C or higher, and even more preferably 35°C or higher.

[0055] (Lubricant) The thermoplastic polyester elastomer-containing composition may contain a lubricant. A lubricant is an additive used during melt extrusion molding to unevenly distribute on the surface of the molded product, reduce adhesion to the roll, and suppress adhesion between sheets. Known lubricants can be used. Examples of lubricants include montanic acid-based metal salts, behenic acid-based metal salts, montanic acid esters, fatty acid amides, polyols, and silicon compounds.

[0056] When a lubricant is included in a thermoplastic polyester elastomer-containing composition, the amount of lubricant may be 0.1 to 5.0 parts by mass per 100 parts by mass of thermoplastic polyester elastomer, preferably 0.1 to 2.0 parts by mass, and more preferably 0.1 to 0.5 parts by mass. If the amount of lubricant is less than 0.1 parts by mass, adhesion to the roll and sticking of sheets to each other may occur, resulting in molding defects. On the other hand, if the amount of lubricant exceeds 5.0 parts by mass, the lubricant may become an impurity during recycling, reducing recyclability. Furthermore, if synthetic leather is used for a long period of time, the lubricant may bleed out onto the surface of the synthetic leather, impairing its appearance.

[0057] (Abrasion resistance improver) The thermoplastic polyester elastomer-containing composition may also contain an abrasion resistance enhancer. The abrasion resistance enhancer is an additive dispersed in the thermoplastic polyester elastomer-containing composition that improves sliding properties, and is not particularly limited as long as it is an additive that acts to improve the abrasion resistance of the surface layer; known additives can be used. Examples of abrasion resistance enhancers include silicone resins, polyolefin resins, and fluororesins. From the viewpoint of compatibility with the thermoplastic polyester elastomer and sliding properties, a silicone-acrylic copolymer containing at least one silicone (polysiloxane) moiety and at least one (meth)acrylic acid polymer moiety is preferred. Examples of such silicone-acrylic copolymers include (acrylates / ethylhexyl acrylate / dimethicone methacrylate) copolymer (product name: KP578) manufactured by Shin-Etsu Silicone Co., Ltd., (acrylates / stearyl acrylate / dimethicone methacrylate) copolymer (product name: KP561P; wax type) manufactured by Shin-Etsu Silicone Co., Ltd., (acrylates / behenyl acrylate / dimethicone methacrylate) copolymer (KP562P) manufactured by Shin-Etsu Silicone Co., Ltd., and Chaline (product name) from Nisshin Chemical Industry Co., Ltd., among others, which are known to have various structures and properties.

[0058] When a thermoplastic polyester elastomer-containing composition contains an abrasion resistance improver, the amount of the abrasion resistance improver may be 0.1 to 10 parts by mass per 100 parts by mass of thermoplastic polyester elastomer, preferably 0.5 to 10 parts by mass, more preferably 1 to 10 parts by mass, even more preferably 1 to 8 parts by mass, and particularly preferably 1 to 6 parts by mass. If the amount of the abrasion resistance improver is less than 0.1 parts by mass, the sliding properties will not be sufficiently improved, and it will be difficult to obtain the effect of improving the abrasion resistance of the surface layer. On the other hand, if the amount of the abrasion resistance improver exceeds 10 parts by mass, it may become an impurity during recycling, reducing recyclability. Furthermore, if the amount of the abrasion resistance improver is excessive, poor compatibility with the thermoplastic polyester elastomer may easily lead to problems such as uneven thickness during melt extrusion molding, or cause defects in the appearance of synthetic leather.

[0059] The thickness of the surface layer is not particularly limited, but for example, it is preferably 10 μm or more, more preferably 20 μm or more, even more preferably 30 μm or more, preferably 500 μm or less, more preferably 150 μm or less, and even more preferably 100 μm or less. That is, the thickness of the surface layer is preferably 10 to 500 μm, more preferably 20 to 150 μm, and even more preferably 30 to 100 μm. A surface layer thickness of 10 μm or more can improve the durability of the synthetic leather, such as abrasion resistance. However, if the surface layer is too thick, it may impair handling and lightness during post-processing.

[0060] Thermoplastic polyester elastomers may be crystalline. Because crystalline properties improve abrasion resistance, even when the surface layer becomes the outermost layer of synthetic leather, it maintains excellent abrasion resistance, thereby increasing the overall durability of the synthetic leather.

[0061] The melting point of thermoplastic polyester elastomer is not particularly limited, but 70 to 210°C is preferred to enable distribution at room temperature without the need for release films or the like.

[0062] The method for forming the epidermal layer is not particularly limited, and the film can be formed using the thermoplastic polyester elastomer-containing composition described above by a known method. For example, known thermal melt film formation methods such as calendering and melt extrusion can be used. Furthermore, this film formation can be carried out on the film alone, on release paper, or on a substrate. As the release paper, a release paper for mold transfer may be used, or a smooth release paper may be used, and by using a release paper for mold transfer, an uneven pattern called a molded pattern can be formed on the surface of the epidermal layer.

[0063] Synthetic leather having a layered structure of epidermal layer / base material layer can be manufactured by layering a base material layer on the surface of an epidermal layer and then heating and pressurizing it in the thickness direction. When layering the base material layer on the surface of the epidermal layer and then heating and pressurizing it, the heating method is not particularly limited and can include heating using a hot roll, hot air heating, or heating in a heating furnace (especially a heating and drying furnace).

[0064] As described above, the synthetic leather in the embodiment includes a base layer and an epidermal layer, and may have an adhesive layer between the base layer and the epidermal layer.

[0065] 3.Adhesive layer The adhesive layer is used to bond the base layer and the epidermis layer, and it has the effect of preventing the base layer and the epidermis layer from separating. However, it is important that it does not hinder the flexibility of the synthetic leather.

[0066] The adhesive layer preferably contains a polyester resin. This makes it easier to recycle the synthetic leather. The adhesive layer is preferably formed using a composition containing a polyester resin (hereinafter sometimes referred to as an adhesive layer forming composition).

[0067] The type of polyester resin that constitutes the adhesive layer is not particularly limited, and examples include polyesters formed by polycondensation of polycarboxylic acid components and polyhydric alcohol components, and polyesters formed by copolymerization of hydroxycarboxylic acids and lactones.

[0068] When the polyester resin constituting the adhesive layer is a polyester formed by polycondensation of a polycarboxylic acid component and a polyhydric alcohol component, it is preferable that at least one of the polycarboxylic acid component or the polyhydric alcohol component is a copolymerized polyester consisting of two or more components. This improves adhesion to the adherend. The polycarboxylic acid component and the polyhydric alcohol component are preferably copolymerized polyesters mainly consisting of a dicarboxylic acid component and a glycol component.

[0069] Examples of polycarboxylic acid components include aromatic polycarboxylic acids, alicyclic polycarboxylic acids, or aliphatic polycarboxylic acids, with aromatic dicarboxylic acids, alicyclic dicarboxylic acids, or aliphatic dicarboxylic acids being preferred, and aromatic dicarboxylic acids being more preferred.

[0070] Examples of aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, orthophthalic acid, and naphthalenedicarboxylic acid. Examples of alicyclic dicarboxylic acids include hexahydrophthalic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid. Examples of aliphatic dicarboxylic acids include saturated aliphatic dicarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, dimer acid, and dodecanedicarboxylic acid; and unsaturated aliphatic dicarboxylic acids such as fumaric acid, maleic acid, and itaconic acid. These dicarboxylic acids may be used individually or in combination of two or more. In addition, tricarboxylic acids or tetracarboxylic acids such as trimellitic acid, trimesic acid, and pyromellitic acid, as well as their anhydrides, may be used as needed.

[0071] When the polycarboxylic acid component contains trifunctional or higher-functioning components, the amount of trifunctional or higher-functioning components is preferably 3 mol% or less relative to 100 mol% of the total amount of polycarboxylic acid components. By keeping the amount of trifunctional or higher-functioning components below the upper limit, gelation during polymerization can be suppressed, and a resin with high molecular weight and excellent flexural resistance can be obtained.

[0072] Examples of polyhydric alcohol components include aromatic polyhydric alcohols, alicyclic polyhydric alcohols, and aliphatic polyhydric alcohols, with aromatic dihydric alcohols, alicyclic dihydric alcohols, and aliphatic dihydric alcohols being preferred, and aliphatic glycols being even more preferred.

[0073] Examples of aliphatic glycols include ethylene glycol, propylene glycol, 1,3-propanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 2-methyl-1,3-propanediol (hereinafter also referred to as 2MG), 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, diethylene glycol, triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol. These aliphatic glycols may be used individually or in combination of two or more.

[0074] As the polyhydric alcohol component, for example, alicyclic polyhydric alcohols such as 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, and tricyclodecanediol; alkylene oxide adducts such as ethylene oxide adducts and propylene oxide adducts of bisphenol A, and ethylene oxide adducts and propylene oxide adducts of hydrogenated bisphenol A; may also be used. In addition, if necessary, triols or tetraols such as trimethylolethane, trimethylolpropane, glycerin, and pentaerythritol may be used.

[0075] The copolymerization amount of aliphatic glycol may be 70 mol% or more, preferably 75 mol% or more, more preferably 80 mol% or more, and even more preferably 90 mol% or more, and may also be 100 mol%, based on 100 mol% of the total amount of polyhydric alcohol components. By having a copolymerization amount of aliphatic glycol above the lower limit, it adheres well to the substrate layer and can be suitably used as an adhesive.

[0076] When the polyester resin constituting the adhesive layer is a polyester copolymerized with hydroxycarboxylic acid and lactone, examples of hydroxycarboxylic acid include glycolic acid, lactic acid, and tartaric acid, and examples of lactone include ε-caprolactone and γ-butyrolactone.

[0077] The polyester resin constituting the adhesive layer may have hydrophilic ionic groups introduced into it to improve adhesion to the substrate layer. Examples of ionic groups include carboxylic acid groups, sulfonic acid groups, phosphate groups, or their metal salts and amine salts. Two or more of these ionic groups may be introduced. Among these, carboxylic acid groups, sulfonic acid groups, or their metal salts are preferred when considering the water resistance and heat and humidity resistance of synthetic leather.

[0078] Methods for introducing carboxylic acid groups into polyester resins constituting the adhesive layer include, for example, adding an acid anhydride compound under normal pressure and a nitrogen atmosphere after polymerization of the polyester resin to carry out an addition reaction, or adding an acid anhydride compound to an oligomer before polycondensation of polyester, followed by a polycondensation reaction under reduced pressure to increase the molecular weight. Examples of acid anhydride compounds include phthalic anhydride, succinic anhydride, maleic anhydride, trimellitic anhydride, itaconic anhydride, citraconic anhydride, monoanhydride of 5-(2,5-dioxotetrahydrofurfuryl)-3-cyclohexen-1,2-dicarboxylic acid, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, pyromelitic anhydride, 1,2,3,4-butanetetracarboxylic dianhydride, 1,2,3,4-pentanetetracarboxylic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, and cyclopentanetetracarboxylic dianhydride. Examples include carboxylic acid dianhydrides, 2,3,6,7-naphthalenetetracarboxylic acid dianhydride, 1,2,5,6-naphthalenetetracarboxylic acid dianhydride, ethylene glycol bistrimellitate dianhydride, 2,2',3,3'-diphenyltetracarboxylic acid dianhydride, thiophene-2,3,4,5-tetracarboxylic acid dianhydride, ethylenetetracarboxylic acid dianhydride, 4,4'-oxydiphthalic acid dianhydride, and 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-3-cyclohexene-1,2-dicarboxylic acid anhydride. These acid anhydride compounds may be used individually or in combination of two or more. When controlling the acid value of the polyester resin constituting the adhesive layer, the former method is preferred, and trimellitic anhydride is preferred as the acid anhydride compound to be added, from the viewpoint of versatility and economy.

[0079] Methods for introducing sulfonic acid groups into polyester resins constituting the adhesive layer include copolymerization of dicarboxylic acids having sulfonic acid groups, such as 5-sulfoisophthalic acid, 4-sulfonaphthalene-2,7-dicarboxylic acid, and 5-[4-sulfophenoxy]isophthalic acid; glycols having sulfonic acid groups, such as 2-sulfo-1,4-butanediol and 2,5-dimethyl-3-sulfo-2,5-hexanediol; and metal salts thereof. Among these, sodium 5-sulfoisophthalate is preferred because it is inexpensive and can be applied to a wide range of uses.

[0080] The ionic group concentration of the polyester resin constituting the adhesive layer may be less than 30 mgKOH / g, preferably less than 25 mgKOH / g, and more preferably less than 20 mgKOH / g. By keeping the ionic group concentration below the upper limit, the water resistance can be increased while maintaining the mechanical strength of the adhesive layer, thereby improving adhesion.

[0081] The method for producing the polyester resin constituting the adhesive layer is not particularly limited, and known methods can be employed. For example, the polycarboxylic acid component and polyhydric alcohol component described above may be esterified at 150 to 250°C, and then polycondensed at 230 to 300°C under reduced pressure. When introducing hydrophilic ionic groups into the polyester resin, monovalent inorganic salts such as sodium acetate and potassium acetate may be added as polymerization stabilizers. In addition, compounds such as hindered phenols or hindered amines may be added as heat stabilizers.

[0082] The polyester resin constituting the adhesive layer may contain amorphous polyester resin. The inclusion of amorphous polyester resin increases the peel strength.

[0083] When forming an adhesive layer containing an amorphous polyester resin, for example, the amorphous polyester resins used may be "Byron GK-680 (Tg=10℃)", "Byron 557 (Tg=-11℃)", "Byron 553 (Tg=-12℃)", "Byron 554 (Tg=-12℃)", "Byron 516 (Tg=-14℃)", "Byron BX-1001 (Tg=-15℃)", "Byron 550 (Tg=-15℃)", "Byron 559 (Tg=-17℃)", etc., manufactured by Toyobo MC Co., Ltd.

[0084] When forming an adhesive layer containing an amorphous polyester resin, for example, an aqueous dispersion of a polyester resin with a Tg of -10°C or lower may be used. Examples of aqueous dispersions of polyester resins with a Tg of -10°C or lower include "Vaironal MD-1930 (Tg=-10°C)", "Vaironal MD-1984 (Tg=-20°C)", and "Vaironal MD-1985 (Tg=-20°C)" manufactured by Toyobo MC Co., Ltd.

[0085] The adhesive layer may have a glass transition temperature (Tg) of -10°C or lower, preferably -13°C or lower, and more preferably -15°C or lower. If the Tg of the adhesive layer exceeds -10°C, the flexibility of the synthetic leather may deteriorate. By keeping the Tg of the adhesive layer at -10°C or lower, the peel strength is increased, and the flexibility of the synthetic leather can be improved.

[0086] To achieve a Tg of -10°C or lower in the adhesive layer, it is preferable to use aromatic dicarboxylic acids and aliphatic glycols as copolymerization components, and it is more preferable to include isophthalic acid, orthophthalic acid, neopentyl glycol, and ethylene glycol. Alternatively, a polyester resin with a desired Tg can be obtained by copolymerizing polycaprolactone.

[0087] The adhesive layer may be formed by applying an adhesive layer-forming composition to the surface of the epidermis layer or the surface of the base layer. The method of applying the adhesive layer-forming composition to the surface of the epidermis layer or the surface of the base layer is not particularly limited and may be by coating or by transfer. A synthetic leather having a layer structure of epidermis layer / adhesive layer / base layer can be manufactured by superimposing a base layer on the adhesive layer side of a laminate obtained by forming an adhesive layer on the surface of the epidermis layer, and then heating and pressing it in the thickness direction. The heating method is not particularly limited and may include heating using a hot roll, hot air heating, or heating in a heating furnace (especially a heating and drying furnace).

[0088] The surface of the epidermal layer constituting the synthetic leather may have a surface treatment layer. The surface treatment layer is a layer that improves the durability of the synthetic leather, improves the gloss of the surface of the synthetic leather, and improves the appearance of the synthetic leather. The surface treatment layer may be composed of a synthetic resin, and polyester resin is preferred as the synthetic resin. The surface treatment layer may also contain polyurethane, acrylic resin, fluororesin, polyvinyl chloride resin, etc., as long as it does not impede recyclability.

[0089] The surface of the synthetic leather may be embossed, for example, to give it a patterned design. [Examples]

[0090] The present invention will be described in more detail below with reference to examples, but the present invention is not limited by the following examples, and it is of course possible to implement modifications within the scope that is consistent with the spirit described above and below, and all such modifications are included within the technical scope of the present invention. Unless otherwise specified, "parts" means "parts by mass" and "%" means "percent mass".

[0091] Each measurement value described in the examples was measured by the following method.

[0092] (Content of soft segments) The soft segment content in thermoplastic polyester elastomers refers to the mass ratio of polytetramethylene glycol to terephthalic acid in the polyester elastomer, and was calculated from the composition ratio of dimethyl terephthalate, 1,4-butanediol, and poly(tetramethylene oxide) glycol used as raw materials.

[0093] (Measurement of reduced viscosity) 0.02 g of a thoroughly dried sample (a thermoplastic polyester elastomer-containing composition) was dissolved in 10 ml of a phenol / tetrachloroethane mixed solvent (mass ratio = 6 / 4), and the reduced viscosity was measured at 30°C using an Ubbelose viscometer.

[0094] (Measurement of acid value) 0.2 g of the sample (thermoplastic polyester elastomer-containing composition) was dissolved in 20 ml of chloroform, and the acid value was determined by titration with 0.01 N potassium hydroxide (ethanol solution). Phenolphthalein was used as the indicator.

[0095] (Measurement of melting point and glass transition temperature) 5 mg of the sample (thermoplastic polyester elastomer-containing composition) was placed in an aluminum pan, sealed with a lid, and measured using a differential scanning calorimetry analyzer "DSC220" manufactured by Seiko Electronics Industries, Ltd. The sample was held at 250°C for 5 minutes to completely melt it, then rapidly cooled with liquid nitrogen, and subsequently heated from -150°C to 250°C at a heating rate of 20°C / min for measurement. In the endothermic curve obtained during heating from -150°C to 250°C, the temperature at the intersection of the baseline before the endothermic peak and the tangent line toward the endothermic peak was defined as the glass transition temperature (Tg, unit: °C). The maximum peak temperature of the heat of fusion was defined as the melting point (Tm, unit: °C).

[0096] In manufacturing synthetic leather, a knitted fabric was prepared to form the base layer, an adhesive layer-forming composition to form the adhesive layer, and a thermoplastic polyester elastomer-containing composition to form the surface layer.

[0097] (base material layer) A polyester circular knit fabric was prepared as the base layer. The prepared polyester circular knit fabric had the following yarn composition: front 84T / 72F, middle 110T / 48F, back 84T / 36F, gauge: 26G, knitting composition: course 79 / inch, welt 39 / inch, with a brushed front, and a thickness of 1.2mm. The basis weight of the base layer was 300g / m 2 That was the case.

[0098] (adhesive layer) A polyester resin was prepared as a composition for forming an adhesive layer. The procedure for producing the prepared polyester resin was as follows: In a reaction vessel equipped with a thermometer, stirrer, reflux condenser, and distillation tube, 228 parts isophthalic acid, 228 parts orthophthalic acid, 9 parts trimellitic anhydride, 150 parts neopentyl glycol, 120 parts ethylene glycol, and tetra-n-butyl titanate (hereinafter sometimes abbreviated as TBT) as a catalyst at a concentration of 0.03 mol% per 100 mol% of the total acid components were charged, and a transesterification reaction was carried out while raising the temperature from 160°C to 240°C over 4 hours. Next, the pressure in the system was gradually reduced to 5 mmHg over 20 minutes, and then a polycondensation reaction was carried out at 260°C for 90 minutes under a vacuum of 0.3 mmHg or less. The mixture was cooled to 230°C under a nitrogen stream, 383 parts ε-caprolactone were added, and the reaction was carried out for 30 minutes to obtain a polyester resin. The obtained polyester resin was amorphous. Furthermore, the glass transition temperature (Tg) of the obtained polyester resin was -16°C, indicating that no ionic groups with hydrophilic groups were introduced.

[0099] (epidermal layer) Thermoplastic polyester elastomers (A-1) to (A-6) were produced according to the method described in Japanese Patent Publication No. 9-59491, and thermoplastic polyester elastomer-containing compositions (A-1') to (A-6'), (A-1''), (A-1'''), and (A-1'''') were produced using the obtained thermoplastic polyester elastomers (A-1) to (A-6).

[0100] Thermoplastic polyester elastomer (A-1) In a reaction vessel equipped with stirring blades, 28 parts dimethyl terephthalate, 19 parts 1,4-butanediol, 72 parts poly(tetramethylene oxide) glycol with a number average molecular weight of 2000, and 0.08 parts titanium tetrabutoxide were charged and heated at 190-230°C for 3 hours to perform transesterification. Next, the temperature was raised to 245°C, the pressure in the system was reduced to 0.2 mmHg, and the mixture was stirred under these conditions for 150 minutes to produce thermoplastic polyester elastomer (A-1). The obtained thermoplastic polyester elastomer (A-1) was discharged in strand form into water and cut into pellets. The amount of soft segments per 100 parts of the obtained thermoplastic polyester elastomer (A-1) is shown in Table 1 below.

[0101] Thermoplastic polyester elastomer (A-2) In a reaction vessel equipped with stirring blades, 53 parts dimethyl terephthalate, 31 parts 1,4-butanediol, 44 parts poly(tetramethylene oxide) glycol with a number average molecular weight of 1000, and 0.08 parts titanium tetrabutoxide were charged and the mixture was heated at 190-230°C for 3 hours to perform transesterification. Next, the temperature was raised to 245°C, the pressure in the system was reduced to 0.2 mmHg, and the mixture was stirred under these conditions for 150 minutes to produce thermoplastic polyester elastomer (A-2). The obtained thermoplastic polyester elastomer (A-2) was discharged in strand form into water and cut into pellets. The amount of soft segments per 100 parts of the obtained thermoplastic polyester elastomer (A-2) is shown in Table 1 below.

[0102] Thermoplastic polyester elastomer (A-3) In a reaction vessel equipped with stirring blades, 28 parts dimethyl terephthalate, 19 parts 1,4-butanediol, 72 parts poly(tetramethylene oxide) glycol with a number average molecular weight of 2000, and 0.08 parts titanium tetrabutoxide were charged and the mixture was heated at 190-230°C for 3 hours to perform transesterification. Next, the temperature was raised to 245°C, the pressure in the system was reduced to 0.2 mmHg, and the mixture was stirred under these conditions for 30 minutes to produce thermoplastic polyester elastomer (A-3). The obtained thermoplastic polyester elastomer (A-3) was extruded in strand form into water and cut into pellets. The amount of soft segments per 100 parts of the obtained thermoplastic polyester elastomer (A-3) is shown in Table 1 below.

[0103] Thermoplastic polyester elastomer (A-4) In a reaction vessel equipped with stirring blades, 28 parts dimethyl terephthalate, 19 parts 1,4-butanediol, 72 parts poly(tetramethylene oxide) glycol with a number average molecular weight of 2000, and 0.08 parts titanium tetrabutoxide were charged and heated at 190-230°C for 3 hours to perform transesterification. Next, the temperature was raised to 245°C, the pressure in the system was reduced to 0.2 mmHg, and the mixture was stirred under these conditions for 150 minutes to produce thermoplastic polyester elastomer (A-4). The obtained thermoplastic polyester elastomer (A-4) was discharged in strand form into water and cut into pellets. Next, the obtained thermoplastic polyester elastomer was placed in a vacuum dryer at 160°C and 0.1 kPa and allowed to stand for 48 hours. The amount of soft segments per 100 parts of the thermoplastic polyester elastomer (A-4) obtained after standing is shown in Table 1 below.

[0104] Thermoplastic polyester elastomer (A-5) In a reaction vessel equipped with stirring blades, 28 parts dimethyl terephthalate, 19 parts 1,4-butanediol, 72 parts poly(tetramethylene oxide) glycol with a number average molecular weight of 2000, and 0.08 parts titanium tetrabutoxide were charged and the mixture was heated at 190-230°C for 3 hours to perform transesterification. Next, the temperature was raised to 260°C, the pressure in the system was reduced to 0.2 mmHg, and the mixture was stirred under these conditions for 150 minutes to produce thermoplastic polyester elastomer (A-5). The obtained thermoplastic polyester elastomer (A-5) was discharged in strand form into water and cut into pellets. The amount of soft segments per 100 parts of the obtained thermoplastic polyester elastomer (A-5) is shown in Table 1 below.

[0105] Thermoplastic polyester elastomer (A-6) In a reaction vessel equipped with stirring blades, 68 parts dimethyl terephthalate, 42 parts 1,4-butanediol, 25 parts poly(tetramethylene oxide) glycol with a number average molecular weight of 1000, and 0.08 parts titanium tetrabutoxide were charged and heated at 190-230°C for 3 hours to perform transesterification. Next, the temperature was raised to 245°C, the pressure in the system was reduced to 0.2 mmHg, and the mixture was stirred under these conditions for 150 minutes to produce thermoplastic polyester elastomer (A-6). The obtained thermoplastic polyester elastomer (A-6) was discharged in strand form into water and cut into pellets. The amount of soft segments per 100 parts of the obtained thermoplastic polyester elastomer (A-6) is shown in Table 1 below.

[0106] Thermoplastic polyester elastomer-containing compositions (A-1')~(A-6'), (A-1''), (A-1'''), (A-1'''') 100 parts of any thermoplastic polyester elastomer (A-1) to (A-6) were dry-blended with a lubricant, weathering agent, and abrasion resistance improver in the proportions shown in Table 1 below. The mixture was melt-kneaded and extruded into strands using a 25 mmφ twin-screw extruder (manufactured by Japan Steel Works, Ltd.) at a temperature setting of 200 to 220°C, water-cooled, and pelletized in a pelletizer. The resulting pellets were dried at 100°C for 4 hours to obtain thermoplastic polyester elastomer-containing compositions (A-1') to (A-6'), (A-1''), (A-1''''), and (A-1''''). As the lubricant, "Wax OP" manufactured by Clariant was used. "Wax OP" is a montanic acid-based metal salt. As the weathering agent, "Chemisorb 73" manufactured by Chemipro, which is commercially available as an ultraviolet absorber, was used. "Chemisorb 73" is a benzotriazole-based ultraviolet absorber with a molecular weight of 315.8 and a melting point of 138-141°C. "Charine R175S" manufactured by Nisshin Chemical Industry Co., Ltd. was used as an abrasion resistance improver. "Charine R175S" is a silicone-acrylic copolymer. For thermoplastic polyester elastomer-containing compositions (A-1') to (A-6'), (A-1''), (A-1'''), and (A-1''''), the reduced viscosity, acid value, melting point, and glass transition temperature (Tg) were measured and are shown in Table 1 below. [Table 1]

[0107] Synthetic leather was manufactured using a polyester circular knit fabric to form the prepared base layer, an adhesive layer-forming composition (polyester resin) to form the adhesive layer, and a thermoplastic polyester elastomer-containing composition to form the surface layer.

[0108] (Example 1) A thermoplastic polyester elastomer-containing composition (A-1') was melt-extruded onto a smooth release paper to create a 50 μm thick surface layer with release paper. Next, a polyester circular knit fabric, which would serve as the base layer, was placed on the side of the surface layer without the release paper to form a laminate. The resulting laminate was bonded using a hot roll at a surface temperature of 190°C for 1 minute, after which the release paper was peeled off to obtain a laminate in which the surface layer and base layer were bonded together. Next, the resulting laminate was heated from the surface layer side, and then an embossed roll with irregularities was pressed onto the cooled surface to transfer the texture of the embossed roll, thereby obtaining a leather-like synthetic leather 1.

[0109] (Example 2) Synthetic leather with a textured finish 2 was obtained under the same conditions as in Example 1, except that thermoplastic polyester elastomer-containing composition (A-2') was used instead of thermoplastic polyester elastomer-containing composition (A-1') in Example 1.

[0110] (Example 3) Synthetic leather with a textured finish 3 was obtained under the same conditions as in Example 1, except that thermoplastic polyester elastomer-containing composition (A-3') was used instead of thermoplastic polyester elastomer-containing composition (A-1') in Example 1.

[0111] (Example 4) A thermoplastic polyester elastomer-containing composition (A-4') was melt-extruded onto a smooth release paper to create a 50 μm thick surface layer with a release paper backing. Next, an adhesive layer-forming composition (polyester resin) was applied to the side of the polyester circular knit fabric used as the base layer that would be bonded to the surface layer, using a gravure coater, with a coating amount of 5 g / m² after drying. 2After applying the material in this manner, it was dried at 120°C to obtain a laminate of the base layer and the adhesive layer. Next, the surface layer with release paper and the laminate of the base layer and adhesive layer were placed on top of each other so that the surface layer and the adhesive layer were in contact. Using a hot roll with a surface temperature of 190°C, the materials were bonded together by heat pressure for 1 minute, after which the release paper was peeled off to obtain a laminate having an adhesive layer between the surface layer and the base layer. Next, the obtained laminate was heated from the surface layer side, and after cooling, an embossed roll with irregularities was pressed against the surface to transfer the texture of the embossed roll, thereby obtaining a leather-textured synthetic leather 4.

[0112] (Examples 5-9) Synthetic leathers 5-9 with a leather-like texture were obtained under the same conditions as in Example 4, except that thermoplastic polyester elastomer-containing compositions (A-5'), (A-6'), (A-1''), (A-1''''), and (A-1'''') were used instead of thermoplastic polyester elastomer-containing composition (A-4') in Example 4.

[0113] (Example 10) A thermoplastic polyester elastomer-containing composition (A-1') was melt-extruded onto a release paper for mold transfer to create a 50 μm thick film, thereby producing a molded surface layer with release paper. Next, a laminate was formed by layering a polyester circular knit fabric, which would serve as the base layer, onto the side of the surface layer of the molded surface layer with release paper that did not have the release paper attached. The resulting laminate was bonded using a hot roll at a surface temperature of 190°C for 1 minute, after which the release paper was peeled off to obtain a leather-like synthetic leather 10 in which the surface layer and the base layer were bonded together.

[0114] The surface hardness of the epidermal layer surface of the obtained synthetic leathers 1 to 10 was measured, and the results are shown in Table 1 above.

[0115] (Comparative Example 1) In Example 4, a comparative leather-like synthetic leather 1 was obtained under the same conditions as in Example 4, except that a polyurethane elastomer resin composition was used instead of the thermoplastic polyester elastomer-containing composition (A-4'). The polyurethane elastomer resin composition used was "Estane® 58315" manufactured by Lubrizol.

[0116] (Comparative Example 2) In Example 4, a comparative textured synthetic leather 2 was obtained under the same conditions as in Example 4, except that a polybutylene terephthalate resin composition was used instead of the thermoplastic polyester elastomer-containing composition (A-4'). The polybutylene terephthalate resin composition used was "EMC-708L" manufactured by Toyobo MC Corporation.

[0117] (Comparative Example 3) In Example 4, a comparative leather-like synthetic leather 3 was obtained under the same conditions as in Example 4, except that a thermoplastic polyester elastomer-containing composition (A-1') was used instead of a thermoplastic polyester elastomer-containing composition (A-4'), and a polyurethane resin was used instead of a polyester resin as the adhesive layer-forming composition. The polyurethane resin used was "Rezamin UD-1305NS" manufactured by Dainichi Seika Kogyo Co., Ltd.

[0118] The obtained synthetic leather samples 1-3 and 10 were cut along the thickness direction, and the thickness of the epidermal layer was measured by observing the cross-section with a scanning electron microscope (SEM). As a result, the thickness of the epidermal layer in all samples was 50 μm. Furthermore, the obtained synthetic leathers 4-9 and comparative synthetic leathers 1-3 were cut along their thickness, and the thickness of the epidermal layer and adhesive layer was measured by observing the cross-section with a scanning electron microscope (SEM). As a result, the thickness of the epidermal layer was 50 μm in all cases, and the thickness of the adhesive layer was 3 μm in all cases.

[0119] The obtained synthetic leathers 1-10 and comparative synthetic leathers 1-3 were evaluated for peel strength, low-temperature flexibility, soft touch, abrasion resistance, recyclability, and melt extrusion moldability, and the evaluation results are shown in Tables 2-1 and 2-2 below.

[0120] (Peel strength) An adhesive tape (2.0 cm wide) having a hot-melt resin layer on the back of a polyester base material was prepared, and the hot-melt resin layer of the adhesive tape was bonded to the surface of the surface layer of synthetic leather using an iron (low temperature 120°C). Then, one end of the adhesive tape was slightly peeled off, and the peeled portion was pulled at a speed of 200 mm / min using an Autograph AG-LS (manufactured by Shimadzu Corporation), and the tensile load (peel strength) at which the polyester base material peeled off from the surface layer was measured.

[0121] (Low temperature flexibility) A test piece measuring 45 mm wide x 70 mm long was cut from the obtained synthetic leather, and the test piece was set in a flexural resistance test device (Yasuda Seiki's "Flexiometer"). The setting method was as follows: Step 1: Open the upper and lower clamps. Step 2: Position the lower end of the upper clamp parallel to the upper end of the lower clamp. Step 3: With the skin layer of the test specimen facing inward, fold the test specimen in half so that the two long sides overlap. Step 4: Secure one end of the folded test specimen to the upper clamp. Step 5: Fold the specimen, which is clamped in place, downwards with the epidermal layer facing outwards, and secure it with the lower clamp. After setting up as described above, the specimen was treated at a bending angle of 22.5°±0.5°, a speed of 100±5 times / min, and a temperature of -20℃. The specimen was then removed, and the presence or absence of damage to the epidermal layer was checked. ○: 10,001 times or more (particularly excellent low-temperature flexibility) △: 5000~10000 cycles (excellent flexibility at low temperatures) ×: 4999 cycles or less (poor low-temperature flexibility)

[0122] (Soft touch) A test piece measuring 20 mm wide x 150 mm long was cut from the obtained synthetic leather. Following Method A as specified in JIS L1096, the rigidity and softness of the synthetic leather were measured using a smooth, horizontal table with a 45° bevel at one end. Based on the measured rigidity and softness, the soft-touch properties of the synthetic leather were evaluated using the following index. ○: Has a rigidity / softness of 0-40 and is particularly excellent in terms of soft touch. △: Has a rigidity / softness rating of 41-80, offering excellent soft-touch properties. ×: The rigidity / softness ratio is 81 or higher, resulting in poor soft-touch properties.

[0123] (Abrasion resistance) A circular test piece with a diameter of 130 mm was cut from the obtained synthetic leather, and a Taber abrasion test was performed using a Taber abrasion test apparatus in accordance with JIS L1096, with a No. CS-10 abrasion wheel, a load of 1 kg, and 2000 friction cycles. The abrasion resistance was evaluated using the following indicators. ○: Grade A rating, indicating exceptionally excellent wear resistance. △: Grade B rating, excellent wear resistance. ×: Class C rating, indicating poor wear resistance.

[0124] (Recyclability) If the base layer and the surface layer are made of the same type of resin, or if the base layer, adhesive layer, and surface layer are made of the same type of resin, the recyclability is evaluated as excellent and marked with a circle (○) in Table 2. If the base layer and the surface layer are made of different types of resin, or if the base layer, adhesive layer, and surface layer are made of different types of resin, the recyclability is evaluated as poor and marked with a cross (×) in Table 2.

[0125] (Melting extrusion properties) Using a single-screw extruder (φ50mm) for film formation, the material was melted at 200-240°C. Then, it was extruded in layers onto an unstretched polypropylene film (release paper) traveling at 80m / min between a 25°C cooling chill roll and a compression roll via a 60cm T-die (lip gap 0.8mm) to obtain a laminate with a 50μm surface layer. The melt extrusion moldability was evaluated based on whether or not the material adhered to the cooling chill roll using the following indicators. ○: No adhesion to the cooling chill roll, and excellent melt extrusion moldability. △: Adhesion to the cooling chill roll results in poor melt extrusion moldability.

[0126] [Table 2-1]

[0127] [Table 2-2]

[0128] From Tables 1, 2-1, and 2-2, the following can be considered. Examples 1-3 and 10 are synthetic leathers in which a base layer made of polyester resin and a surface layer obtained using a thermoplastic polyester elastomer-containing composition are laminated. Since the base layer and the surface layer are made of the same type of resin, they have excellent recyclability. They also have high peel strength and excellent durability. Furthermore, they have excellent flexibility (especially low-temperature flexibility). Examples 4-9 are synthetic leathers having an adhesive layer containing polyester resin between a base layer made of polyester resin and a surface layer obtained using a thermoplastic polyester elastomer-containing composition. Since the base layer, adhesive layer, and surface layer are made of the same type of resin, they have excellent recyclability. Furthermore, they have high peel strength and excellent durability. Furthermore, they have excellent flexibility (especially low-temperature flexibility). In Example 4, the reason why the melt extrusion moldability is marked with a triangle (△) is because a defect in appearance occurred. In Example 9, the reason why the melt extrusion moldability is marked with a triangle (△) is because roll wrapping occurred.

[0129] Comparative Example 1 is a synthetic leather having an adhesive layer containing a polyester resin between a base layer made of a polyester resin and a surface layer obtained using a thermoplastic polyurethane elastomer-containing composition. Although the base layer and the adhesive layer are made of the same type of resin, the surface layer is made of a different type of resin than the base layer and the adhesive layer, making it difficult to recycle. Comparative Example 2 is a synthetic leather having an adhesive layer containing a polyester resin between a base layer made of a polyester resin and a surface layer obtained using a composition that does not contain a thermoplastic polyester elastomer. It has low peel strength, poor durability, and poor flexibility. Comparative Example 3 is a synthetic leather having an adhesive layer containing a polyurethane resin between a base layer made of a polyester resin and a surface layer obtained using a thermoplastic polyester elastomer-containing composition. Although the base layer and the surface layer are made of the same type of resin, the adhesive layer is made of a different type of resin than the base layer and the surface layer, making it difficult to recycle.

Claims

1. Synthetic leather comprising a base layer and an epidermal layer, The aforementioned substrate layer contains a polyester resin, The aforementioned surface layer is synthetic leather containing a thermoplastic polyester elastomer-containing composition.

2. The aforementioned thermoplastic polyester elastomer is It consists of a hard segment and a soft segment joined together. The hard segment is made of a polyester comprising an aromatic dicarboxylic acid and an aliphatic diol and / or an alicyclic diol as constituent components. The soft segment comprises at least one selected from aliphatic polyethers, aliphatic polyesters, and aliphatic polycarbonates. The synthetic leather according to claim 1, wherein the thermoplastic polyester elastomer-containing composition contains 30 to 90% by mass of the soft segment with respect to 100% by mass of the thermoplastic polyester elastomer.

3. The synthetic leather according to claim 1, wherein the thermoplastic polyester elastomer-containing composition has a glass transition temperature (Tg) of -30°C or lower.

4. The synthetic leather according to claim 1, wherein the thermoplastic polyester elastomer-containing composition has an acid value of 60 eq / t or less.

5. The synthetic leather according to claim 1, wherein the thermoplastic polyester elastomer-containing composition has a reduced viscosity of 1.0 to 3.5 dl / g.

6. The synthetic leather according to claim 1, wherein the thermoplastic polyester elastomer-containing composition contains 0.01 to 3.0 parts by mass of a weather-resistant agent per 100 parts by mass of the thermoplastic polyester elastomer.

7. The synthetic leather according to claim 1, wherein the thermoplastic polyester elastomer-containing composition contains 0.1 to 5.0 parts by mass of a lubricant per 100 parts by mass of the thermoplastic polyester elastomer.

8. The synthetic leather according to claim 1, wherein the thermoplastic polyester elastomer-containing composition contains 0.1 to 10 parts by mass of an abrasion resistance improver per 100 parts by mass of the thermoplastic polyester elastomer.

9. The synthetic leather according to claim 1, having an adhesive layer containing a polyester resin between the base material layer and the surface layer.

10. The synthetic leather according to claim 9, wherein the adhesive layer contains a resin having a glass transition temperature (Tg) of -10°C or lower.

11. The synthetic leather according to claim 9, wherein the polyester resin constituting the adhesive layer is amorphous.

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