Polyester resin composition, artificial leather, and method for producing the same

Abstract

To provide a polyester resin composition that can achieve high abrasion resistance, high heat resistance, and a good texture. [Solution] The polyester resin composition contains a polyester resin having a metal sulfonate group. The polyester resin contains polycarboxylic acid residues including metal sulfonate group-containing polycarboxylic acid residues and aromatic polycarboxylic acid residues, and polyhydric alcohol residues including ethylene glycol residues as structural units. The content of metal sulfonate group-containing polycarboxylic acid residues is 0.5 mol% to 10 mol% of the total amount of polycarboxylic acid residues. The content of aromatic polycarboxylic acid residues is 50 mol% to 99.5 mol% of the total amount of polycarboxylic acid residues. The polyester resin has a glass transition temperature of 0°C to 55°C and an acid value of 20 mg KOH / g or less.

Description

Technical Field

[0001] The present disclosure generally relates to a polyester resin composition, artificial leather, and a manufacturing method thereof, and more particularly to a polyester resin composition containing a polyester resin having a metal sulfonate group, artificial leather containing this polyester resin composition, and a manufacturing method thereof.

Background Art

[0002] Patent Document 1 describes artificial leather using polyester. As this polyester, a polyester copolymer used for an adhesive layer of artificial leather and a polyether ester-based BLOCK copolymer used for a skin film layer of artificial leather are described. The polyester copolymer is characterized by having a melting point of 100 to 170°C, a hardness of 20 to 40D, a melt index (MI) of 10 to 50 g / 10 min, and a temperature of 190°C / 2.16 kg load. The polyether ester-based BLOCK copolymer is produced by condensation polymerization of terephthalic acid, 1,4-butanediol, and polytetraethylene glycol. The artificial leather using this polyester is said to have excellent durability.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] As characteristics of artificial leather, in addition to excellent durability, it is desired that the texture of the surface of the artificial leather is also good. However, with the polyester of Patent Document 1, there is room for improvement from the viewpoint of achieving high abrasion resistance, high heat resistance, and good texture of the artificial leather using this polyester.

[0005] The purpose of this disclosure is to provide a polyester resin composition, artificial leather, and a method for producing artificial leather that can achieve high abrasion resistance, high heat resistance, and a good texture. [Means for solving the problem]

[0006] A polyester resin composition according to one aspect of the present disclosure is a polyester resin composition contained in artificial leather, and contains a polyester resin having a metal sulfonate group. The polyester resin contains polycarboxylic acid residues including a metal sulfonate group-containing polycarboxylic acid residue and an aromatic polycarboxylic acid residue, and polyhydric alcohol residues including an ethylene glycol residue as structural units. The content of the metal sulfonate group-containing polycarboxylic acid residue is 0.5 mol% to 10 mol% of the total amount of the polycarboxylic acid residues. The content of the aromatic polycarboxylic acid residue is 50 mol% to 99.5 mol% of the total amount of the polycarboxylic acid residues. The polyester resin has a glass transition temperature of 0°C to 55°C and an acid value of 20 mgKOH / g or less.

[0007] Artificial leather according to one aspect of the present disclosure comprises a base layer containing a polyester fabric, an intermediate layer containing a polyester resin composition for the intermediate layer, and a surface layer containing a polyester resin composition for the surface layer. The polyester resin composition for the intermediate layer and the polyester resin composition for the surface layer each contain the polyester resin composition.

[0008] A method for manufacturing artificial leather according to one aspect of the present disclosure is a method for manufacturing artificial leather comprising a base layer containing polyester fabric, an intermediate layer containing a polyester resin composition for the intermediate layer, and a surface layer containing a polyester resin composition for the surface layer, laminated in this order. Each of the polyester resin composition for the intermediate layer and the polyester resin composition for the surface layer contains a polyester resin having a metal sulfonate group. The method comprises the steps of forming the surface layer by applying an aqueous dispersion of the polyester resin composition for the surface layer onto a release substrate and drying it, forming the intermediate layer by applying an aqueous dispersion of the polyester resin composition for the intermediate layer onto the surface layer and drying it, stacking the base layer on the intermediate layer and pressing the intermediate layer and the base layer together, and peeling the release substrate from the surface layer. [Effects of the Invention]

[0009] According to this disclosure, it is possible to provide a polyester resin composition, artificial leather, and a method for manufacturing artificial leather that can achieve high abrasion resistance, high heat resistance, and good texture. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a schematic cross-sectional view showing artificial leather according to an embodiment. [Modes for carrying out the invention]

[0011] The following describes a polyester resin composition, artificial leather 1, and a method for producing the same according to embodiments of this disclosure. Note that the following embodiments are only a part of the various embodiments of this disclosure. The following embodiments can be modified in various ways depending on the design, as long as the objectives of this disclosure are achieved.

[0012] 1. Overview The polyester resin composition according to the embodiment of this disclosure is a polyester resin composition contained in artificial leather 1. Specifically, this polyester resin composition is a polyester resin composition contained in at least one selected from the group consisting of the intermediate layer 3 and the surface layer 4 in artificial leather 1, which comprises a base layer 2 containing polyester fabric, an intermediate layer 3, and a surface layer 4. The polyester resin composition contains a polyester resin having a metal sulfonate group. The polyester resin contains polycarboxylic acid residues including metal sulfonate group-containing polycarboxylic acid residues and aromatic polycarboxylic acid residues, and polyhydric alcohol residues including ethylene glycol residues as structural units. The content of metal sulfonate group-containing polycarboxylic acid residues is 0.5 mol% to 10 mol% of the total amount of polycarboxylic acid residues. The content of aromatic polycarboxylic acid residues is 50 mol% to 99.5 mol% of the total amount of polycarboxylic acid residues. The polyester resin has a glass transition temperature of 0°C to 55°C and an acid value of 20 mgKOH / g or less.

[0013] Because the polyester resin composition possesses the above-mentioned components, it is possible to achieve high abrasion resistance, high heat resistance, and a good texture in the artificial leather 1 using the polyester resin composition. Note that high abrasion resistance, high heat resistance, and a good texture are sometimes collectively referred to as the various physical properties of the artificial leather 1.

[0014] In this disclosure, a polycarboxylic acid residue refers to the portion of a polycarboxylic acid obtained by removing the OH group from the carboxyl group, or the portion of a polycarboxylic acid ester obtained by removing the OR group from the -COOR ester structure, where R represents a hydrocarbon group. A polyhydric alcohol residue refers to the portion of a polyhydric alcohol obtained by removing the hydrogen atom from the hydroxyl group. Artificial leather is a general term for materials made to imitate the appearance and texture of natural leather, and includes synthetic leather and artificial leather.

[0015] 2.Details 2.1. Polyester resin composition The polyester resin composition according to this embodiment (hereinafter also referred to as composition (M)) contains a polyester resin having a metal sulfonate group. Thereby, the hydrophilicity is improved and it can be dispersed in a solvent mainly composed of water.

[0016] (1) Polyester resin (Components) The polyester resin is a compound obtained by polycondensing a polyvalent carboxylic acid component and a polyhydric alcohol component by an ester-forming reaction. That is, the polyester resin is a copolymer containing a structural unit composed of a polyvalent carboxylic acid residue derived from the polyvalent carboxylic acid component and a structural unit composed of a polyhydric alcohol residue derived from the polyhydric alcohol component. This polycondensation may be dehydration condensation or dealcoholization condensation.

[0017] The weight average molecular weight of the polyester resin is not particularly limited, but for example, it is preferably 3,000 or more and 200,000 or less, more preferably 5,000 or more and 150,000 or less, and still more preferably 10,000 or more and 120,000 or less. Within the above range, the water dispersibility of the polyester resin can be improved and the decrease in the hydrolysis resistance of the artificial leather 1 can be suppressed. The method for measuring the weight average molecular weight will be described in detail in the examples.

[0018] <Polyvalent carboxylic acid component> The polyvalent carboxylic acid component is a compound containing a polyvalent carboxylic acid residue. That is, the polyvalent carboxylic acid component is at least one compound selected from the group consisting of a polyvalent carboxylic acid, its ester and anhydride. The polyvalent carboxylic acid ester is, for example, an ester compound of a polyvalent carboxylic acid and an alkyl alcohol having 1 to 6 carbon atoms. The polyvalent carboxylic acid component provides a structural unit composed of a polyvalent carboxylic acid residue in the polyester resin.

[0019] The polyvalent carboxylic acid component includes a polyvalent carboxylic acid component containing a metal sulfonate group and an aromatic polyvalent carboxylic acid component. That is, the polyester resin contains a polyvalent carboxylic acid residue containing a metal sulfonate group and an aromatic polyvalent carboxylic acid residue as structural units.

[0020] The polyvalent carboxylic acid component containing a metal sulfonate group has one or more metal sulfonate groups in the molecule. That is, the polyvalent carboxylic acid component containing a metal sulfonate group provides a structural unit composed of a metal sulfonate group-containing polyvalent carboxylic acid residue in the polyester resin. Examples of the polyvalent carboxylic acid component containing a metal sulfonate group include compounds in which one or more metal sulfonate groups are bonded to the hydrocarbon group of the polyvalent carboxylic acid component.

[0021] Here, the metal sulfonate group refers to the metal base of the sulfonic acid group (-SO3H). The metal sulfonate group is, for example, -SO3 - (M n+ ) 1 / n represented by, where M n+ is an n-valent metal cation, and n is an integer from 1 to 6. It is preferable that n is from 1 to 3, more preferably 1 or 2, and even more preferably 1. Examples of the metal cation include monovalent metal cations such as alkali metal ions such as lithium ion, sodium ion, potassium ion, rubidium ion, cesium ion; divalent metal cations such as alkaline earth metal ions such as magnesium ion, calcium ion, strontium ion, barium ion, etc. The polyvalent carboxylic acid component containing a metal sulfonate group may have one or two or more metal sulfonate groups, but one is preferable.

[0022] The polyvalent carboxylic acid component containing a metal sulfonate group is not particularly limited, and examples thereof include aromatic dicarboxylates having a metal sulfonate group. Examples of the aromatic dicarboxylate include sulfophthalates such as 2-sulfoisophthalate, 4-sulfoisophthalate, 5-sulfoisophthalate, and 4-sulfo-2,6-naphthalenedicarboxylate.

[0023] The metal sulfonate group-containing polycarboxylic acid component preferably includes an aromatic dicarboxylate, more preferably a sulfobenzenedicarboxylate, and even more preferably a 5-sulfoisophthalate. In this case, the water dispersibility of the polyester resin can be improved, and the stability of the aqueous dispersion of the polyester resin can be improved.

[0024] The aromatic polycarboxylic acid component is not particularly limited, but examples include aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, and 2,5-franzicarboxylic acid; aromatic tricarboxylic acids such as trimellitic acid, hemimellitic acid, trimedic acid, and 1,2,5-naphthalentricarboxylic acid; aromatic tetracarboxylic acids such as pyromellitic acid, their esters, and anhydrides.

[0025] The aromatic polycarboxylic acid preferably includes at least one selected from the group consisting of aromatic dicarboxylic acids, their esters, and anhydrides, and more preferably includes at least one selected from the group consisting of isophthalic acid, terephthalic acid, their esters, and anhydrides. In this case, the water dispersibility of the polyester resin can be improved by moderately lowering the crystallinity of the polyester resin, thereby improving the stability of the polyester resin aqueous dispersion.

[0026] The polycarboxylic acid component may further contain an aliphatic polycarboxylic acid component. In other words, the polyester resin may further contain aliphatic polycarboxylic acid residues as structural units.

[0027] The aliphatic polycarboxylic acid component is not particularly limited, but examples include alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid; alicyclic tricarboxylic acids such as 1,2,4-cyclohexanetricarboxylic acid; aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, dodecanedioic acid, and dimer acid; aliphatic tricarboxylic acids such as 1,2,3-butanetricarboxylic acid, their esters, and anhydrides.

[0028] The aliphatic polycarboxylic acid component preferably includes at least one selected from the group consisting of aliphatic dicarboxylic acids, their esters, and anhydrides, and more preferably includes at least one selected from the group consisting of sebacic acid, dodecanediic acid, their esters, and anhydrides. In this case, the adhesion of composition (M) to the substrate layer 2 can be improved.

[0029] The polyvalent carboxylic acid component may further contain trivalent or higher carboxylic acid components. In this case, a cross-linking structure is formed within the polyester resin molecule due to trivalent or higher carboxylic acid residues. This allows for adjustment of various properties of the polyester resin, such as the glass transition temperature and weight-average molecular weight.

[0030] From the perspective of reducing environmental impact, it is also preferable to use biomass-derived polycarboxylic acid components as the polycarboxylic acid component. Examples of biomass-derived polycarboxylic acid components include 2,5-franzicarboxylic acid, succinic acid, adipic acid, sebacic acid, dodecanediic acid, and dimer acid.

[0031] <Polyhydric alcohol components> Polyhydric alcohol components are compounds containing polyhydric alcohol residues. In other words, polyhydric alcohol components are alcohol compounds with two or more hydric values. Polyhydric alcohol components provide structural units consisting of polyhydric alcohol residues in polyester resins.

[0032] The polyhydric alcohol component is not particularly limited, but examples include aliphatic diols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, dimerdiol, 1,9-nonanediol, and 1,10-decanediol; alicyclic diols such as 1,4-cyclohexanedimethanol; alicyclic heterocyclic diols such as isosorbide; aromatic diols such as 1,4-benzenedimethanol and 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene; ether group-containing diols such as diethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol, and polytetramethylene ether glycol; aliphatic triols such as glycerol and trimethylolpropane; alicyclic triols such as 1,2,4-cyclohexanetrimethanol; triol compounds such as aromatic triols such as benzenetrimethanol; and tetraol compounds such as pentaerythritol.

[0033] The polyhydric alcohol component contains ethylene glycol. In other words, polyester resin contains ethylene glycol residues as structural units.

[0034] The polyhydric alcohol component may further contain aliphatic polyhydric alcohol components other than ethylene glycol. In other words, the polyester resin may further contain aliphatic polyhydric alcohol residues other than ethylene glycol residues (hereinafter referred to as aliphatic polyhydric alcohol residues (L)) as structural units.

[0035] The aliphatic polyhydric alcohol residue (L) preferably contains an aliphatic diol other than ethylene glycol, and more preferably contains at least one selected from the group consisting of 1,4-butanediol and 1,6-hexanediol. In this case, the adhesion of composition (M) to the substrate layer 2 can be improved.

[0036] The polyhydric alcohol component may further contain trihydric or higher alcohol components. In this case, a cross-linked structure is formed within the polyester resin molecule due to the trihydric or higher alcohol residues. This allows for adjustment of various properties of the polyester resin, such as the glass transition temperature and weight-average molecular weight.

[0037] From an environmental perspective, it is also preferable to use biomass-derived polyhydric alcohol components. Examples of biomass-derived polyhydric alcohol components include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, 1,9-nonanediol, 1,10-decanediol, polyethylene glycol, dimer diol, isosorbide, and glycerol.

[0038] <Content and composition ratio of each constituent unit> The content of metal sulfonate group-containing polycarboxylic acid residues is 0.5 mol% or more, preferably 1 mol% or more, and more preferably 2 mol% or more, relative to the total amount of polycarboxylic acid residues. In this case, the water dispersibility of the polyester resin can be improved. The content of metal sulfonate group-containing polycarboxylic acid residues is 10 mol% or less, preferably 8 mol% or less, and more preferably 6 mol% or less, relative to the total amount of polycarboxylic acid residues. In this case, the decrease in the hydrolysis resistance of artificial leather 1 can be suppressed. In this disclosure, "total amount of polycarboxylic acid residues" refers to 100 mol%. Therefore, the content of each polycarboxylic acid residue represents the ratio of the number of moles of each polycarboxylic acid residue to the total number of moles of polycarboxylic acid residues in the polyester resin.

[0039] The content of aromatic polycarboxylic acid residues is 50 mol% or more, preferably 60 mol% or more, and more preferably 65 mol% or more, relative to the total amount of polycarboxylic acid residues. In this case, the abrasion resistance and heat resistance of the artificial leather 1 can be improved. The content of aromatic polycarboxylic acid residues is 99.5 mol% or less, preferably 97 mol% or less, and more preferably 95 mol% or less, relative to the total amount of polycarboxylic acid residues. In this case, the texture of the artificial leather 1 can be improved. Furthermore, when polyester resin is contained in the epidermal layer 4 of the artificial leather 1, the content of aromatic polycarboxylic acid residues is more preferably 70 mol% or more, and particularly preferably 80 mol% or more, relative to the total amount of polycarboxylic acid residues. In this case, the abrasion resistance and heat resistance of the artificial leather 1 can be further improved.

[0040] The content of aliphatic polycarboxylic acid residues is, for example, more than 0 mol%, preferably 3 mol% or more, and more preferably 5 mol% or more, relative to the total amount of polycarboxylic acid residues. The content of aliphatic polycarboxylic acid residues is, preferably 40 mol% or less, preferably 30 mol% or less, and more preferably 25 mol% or less, relative to the total amount of polycarboxylic acid residues. Within the above range, the glass transition temperature of the polyester resin can be adjusted, and good physical properties of the artificial leather 1 can be achieved. Furthermore, when the polyester resin is contained in the intermediate layer 3 of the artificial leather 1, the content of aliphatic polycarboxylic acid residues is, even more preferably 10 mol% or more, and particularly preferably 15 mol% or more, relative to the total amount of polycarboxylic acid residues. In this case, the adhesion between the intermediate layer 3 containing the polyester resin and the base layer 2 and the surface layer 4 can be improved, and the texture of the artificial leather 1 can be improved.

[0041] When the polycarboxylic acid component includes a polycarboxylic acid component with a trivalent or higher valent

[0042] The content of ethylene glycol residues is preferably 50 mol% or more, more preferably 55 mol% or more, and even more preferably 60 mol% or more, relative to the total amount of polyhydric alcohol residues. In this case, the adhesion of composition (M) to the base layer 2 can be improved, and if the base layer 2 is a polyester base material, the above adhesion can be particularly improved. The content of ethylene glycol residues is preferably 100 mol% or less, more preferably 98 mol% or less, and even more preferably 95 mol% or less, relative to the total amount of polyhydric alcohol residues. In this case, the texture of the artificial leather 1 can be improved. Furthermore, if polyester resin is contained in the epidermal layer 4 of the artificial leather 1, the content of ethylene glycol residues is even more preferably 60 mol% or more, and especially preferably 70 mol% or more, relative to the total amount of polyhydric alcohol residues. In this case, the abrasion resistance and heat resistance of the artificial leather 1 can be further improved. In this disclosure, "total amount of polyhydric alcohol residues" means 100 mol%. Therefore, the content of each polyhydric alcohol residue represents the ratio of the number of moles of each polyhydric alcohol residue to the total number of moles of polyhydric alcohol residues in the polyester resin.

[0043] The content of aliphatic polyhydric alcohol residues (L) is preferably more than 0 mol%, preferably 2 mol% or more, and more preferably 5 mol% or more, relative to the total amount of polyhydric alcohol residues. The content of aliphatic polyhydric alcohol residues (L) is preferably 50 mol% or less, more preferably 40 mol% or less, and even more preferably 30 mol% or less, relative to the total amount of polyhydric alcohol residues. Within the above range, the glass transition temperature of the polyester resin can be adjusted, and good physical properties of the artificial leather 1 can be achieved. Furthermore, when the polyester resin is contained in the intermediate layer 3 of the artificial leather 1, the content of aliphatic polyhydric alcohol residues (L) is more preferably 10 mol% or more, and particularly preferably 15 mol% or more, relative to the total amount of polyhydric alcohol residues. In this case, the adhesion between the intermediate layer 3 containing the polyester resin and the base layer 2 and the surface layer 4 can be improved, and the texture of the artificial leather 1 can be improved.

[0044] When the polyhydric alcohol component includes a trivalent or higher polyhydric alcohol component, the content of the trivalent or higher polyhydric alcohol residue is preferably 5 mol% or less, more preferably 3 mol% or less, and even more preferably 2 mol% or less, relative to the total amount of polyhydric alcohol residues. In this case, the generation of crosslinked structures caused by the trivalent or higher polyhydric alcohol residues within the polyester resin molecule can be controlled. This further improves the water dispersibility of the polyester resin and the stability of the polyester resin aqueous dispersion.

[0045] In the polyester resin contained in composition (M) suitably used for the epidermal layer 4, the total content of aliphatic polycarboxylic acid residues and aliphatic polyalcohol residues (L) is preferably 10 mol% to 50 mol%, and more preferably 20 mol% to 45 mol%, relative to a total of 200 mol% of polycarboxylic acid residues and polyalcohol residues. Within this range, the glass transition temperature of the polyester resin contained in composition (M) suitably used for the epidermal layer 4 can be adjusted, and good physical properties of the artificial leather 1 can be achieved.

[0046] In the polyester resin contained in composition (M) suitably used in the intermediate layer 3, the total content of aliphatic polycarboxylic acid residues and aliphatic polyalcohol residues (L) is preferably 20 mol% to 60 mol%, and more preferably 30 mol% to 55 mol%, relative to a total of 200 mol% of polycarboxylic acid residues and polyalcohol residues. Within this range, the glass transition temperature of the polyester resin contained in composition (M) suitably used in the intermediate layer 3 can be adjusted, and good physical properties of the artificial leather 1 can be achieved.

[0047] <Recycled polyester> The polyester resin may contain structural units derived from recycled polyester to the extent that it achieves the effects of this embodiment. Specifically, the polyester resin may contain structural units derived from compound residues produced by depolymerizing recycled polyester. Examples of such compound residues include terephthalic acid residues and ethylene glycol residues.

[0048] Recycled polyester contains polyethylene terephthalate as its main component. The main component refers to the component with the highest proportion. The proportion of polyethylene terephthalate in recycled polyester is preferably 90% by mass or more, more preferably 95% by mass or more, and even more preferably 99% by mass or more. In this case, a reduction in environmental impact can be achieved. The aforementioned proportion may also be 100% by mass.

[0049] Examples of recycled polyester include material recycled polyester, mechanically recycled polyester, and chemically recycled polyester. Material recycled polyester refers to polyester obtained by sorting, crushing, washing, etc., used or discarded polyester molded products such as bottles, containers, and films to remove contaminants and foreign matter, and then flaketing them. Mechanically recycled polyester refers to polyester obtained by treating material recycled polyester flakes at high temperature and under reduced pressure for a certain period of time to remove contaminants from inside the resin, and by adjusting the degree of polymerization by repolymerizing a portion of the polyester. Chemical recycled polyester refers to polyester obtained by decomposing polyester to the monomer level and then repolymerizing these monomers.

[0050] The intrinsic viscosity (IV value, unit: dl / g) of recycled polyester is preferably 0.40 to 1.20, and more preferably 0.45 to 1.00, from the viewpoint of more appropriate depolymerization reactions. Intrinsic viscosity is generally used as an indicator of the degree of polymerization of a polymer.

[0051] From the viewpoint of further reducing the environmental impact, recycled polyester preferably includes at least one of material recycled polyester and mechanically recycled polyester. Furthermore, from the viewpoint of improving the quality of the polyester resin, recycled polyester is more preferably made up of mechanically recycled polyester, and even more preferably made up of mechanically recycled polyester obtained by recovering PET bottles or PET films.

[0052] When using recycled polyester, the content of compound residues derived from the recycled polyester is preferably 30 mol% to 80 mol% of the total amount of residues contained in the polyester resin. In this case, the environmental burden can be further reduced, and the crystallinity of the polyester resin derived from the recycled polyester can be moderately lowered, thereby improving the water dispersibility of the polyester resin.

[0053] (Manufacturing method) A method for producing polyester resin can be carried out, for example, by a step of blending a polycarboxylic acid component and a polyhydric alcohol component as raw materials and carrying out an ester formation reaction in the blended raw materials (hereinafter also referred to as step (I)), and a step of carrying out a polycondensation reaction by reducing the pressure of the reaction system (hereinafter also referred to as step (II)).

[0054] The reaction temperature in step (I) is preferably 150°C to 270°C, and more preferably 200°C to 260°C. This reaction temperature may also be changed in steps. The reaction time in step (I) is preferably 1 hour to 10 hours, and more preferably 2 hours to 8 hours. From the viewpoint of promoting the ester formation reaction in step (I), the reaction system is preferably at atmospheric pressure.

[0055] In step (I), it is preferable to use a catalyst to further promote the ester formation reaction. The catalyst is not particularly limited, but examples include titanium oxalates such as potassium titanium oxalate and sodium titanium oxalate; titanium alkoxides such as tetra-n-propyl titanate and tetra-n-butyl titanate; titanium fatty acid salts such as titanium acetate; titanium catalysts such as inorganic titanium compounds such as titanium oxides; manganese fatty acid salts such as manganese acetate; manganese catalysts such as manganese carbonate; antimony catalysts such as antimony trioxide; aluminum catalysts such as aluminum trisacetyl acetate; germanium catalysts such as germanium dioxide; and lithium catalysts such as sec-butyllithium.

[0056] The reaction temperature in step (II) is preferably 150°C to 270°C, and more preferably 200°C to 260°C. The degree of reduced pressure in step (II) is preferably 25 hPa or less, and more preferably 10 hPa or less. These reaction temperatures and degrees of reduced pressure may also be changed in steps. By adjusting the reaction temperature, degree of reduced pressure, and reaction time in step (II), various properties of the polyester resin, such as the glass transition temperature and weight-average molecular weight, can be adjusted.

[0057] When using recycled polyester, the depolymerization reaction can be carried out simultaneously with the ester formation reaction in step (I), or between steps (I) and (II). In the former case, recycled polyester is added to the polycarboxylic acid component and polyhydric alcohol component as raw materials, and the ester formation reaction and depolymerization reaction are carried out simultaneously in the added raw materials. In this case, the reaction temperature, reaction time, and pressure of the reaction system may be the same as those for step (I) described above. In the latter case, recycled polyester is further added after step (I), and the depolymerization reaction is carried out. The reaction temperature in the depolymerization reaction is preferably 200°C to 270°C, more preferably 210°C to 260°C. This reaction temperature may also be changed in stages. The reaction time in the depolymerization reaction is preferably 1 hour to 8 hours, more preferably 2 hours to 5 hours. From the viewpoint of further promoting the depolymerization reaction, it is preferable that the reaction system be at atmospheric pressure.

[0058] (Physical properties) <Glass transition temperature> The glass transition temperature (Tg) of the polyester resin is between 0°C and 55°C. If the Tg of the polyester resin is 0°C or higher, the heat resistance and abrasion resistance of the artificial leather 1 using composition (M) can be improved. If the Tg of the polyester resin is 55°C or lower, the texture of the artificial leather 1 using composition (M) can be improved.

[0059] When composition (M) is included in the intermediate layer 3 of artificial leather 1, the Tg of the polyester resin contained in composition (M) is preferably 0°C to 40°C, more preferably 5°C to 35°C, and even more preferably 10°C to 30°C. If this Tg is 0°C or higher, the heat resistance of the artificial leather 1 using composition (M) in the intermediate layer 3 can be further improved. If this Tg is 40°C or lower, the texture of the artificial leather 1 using composition (M) in the intermediate layer 3 can be further improved.

[0060] When composition (M) is contained in the surface layer 4 of artificial leather 1, the Tg of the polyester resin contained in composition (M) is preferably 25°C or higher and 55°C or lower, and more preferably more than 30°C and 50°C or lower. If this Tg is 25°C or higher, the heat resistance and abrasion resistance of the artificial leather 1 using composition (M) in the surface layer 4 can be further improved. If this Tg is 55°C or lower, the texture of the artificial leather 1 using composition (M) can be further improved.

[0061] <Acid value> It is important that the acid value of the polyester resin is 20 mg KOH / g or less. An acid value of 20 mg KOH / g or less improves the water dispersibility of the polyester resin and enhances the stability of the polyester resin aqueous dispersion. If the acid value of the polyester resin exceeds 20 mg KOH / g, the water dispersibility of the polyester resin and the stability of the polyester resin aqueous dispersion decrease. The acid value of the polyester resin is preferably 15 mg KOH / g or less, more preferably 12 mg KOH / g or less, and even more preferably 10 mg KOH / g or less. The acid value of the polyester resin may, for example, be 0 mg KOH / g. Note that the "acid value" of the polyester resin refers to the mass (mg) of potassium hydroxide required to neutralize 1 g of the polyester resin. Furthermore, the acid value of the polyester resin is a value caused by carboxyl groups, etc., present in the side chains or terminals of the polyester resin molecule.

[0062] (2) Additives Composition (M) may contain additives other than polyester resin having metal sulfonate groups, to the extent that it achieves the effects of this embodiment. The additives are not particularly limited, but examples include pigments, dyes, thickeners, crosslinking agents, leveling agents, inorganic fillers, and the like.

[0063] The pigment is a component that colors composition (M). The added pigment is preferably in the form of an aqueous dispersion. In this case, when the pigment and the aqueous dispersion of composition (M) are mixed, problems such as variations in color intensity and uneven coloring due to mottled patterns can be suppressed.

[0064] A thickening agent is a component that adjusts the viscosity of the aqueous dispersion of composition (M). Examples of thickening agents include polymeric thickening agents, inorganic thickening agents, and surfactant-type thickening agents.

[0065] The crosslinking agent is a component that crosslinks the molecular chains in the polyester resin contained in composition (M). Crosslinking the molecular chains can improve the various physical properties of the artificial leather 1. The crosslinking agent is not particularly limited, but examples include isocyanate-based crosslinking agents, carbodiimide-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, epoxy-based crosslinking agents, etc. When composition (M) contains a crosslinking agent, the content of the crosslinking agent is, for example, 5% by mass or less based on the total amount of the aqueous dispersion of composition (M).

[0066] (3) Manufacturing method Composition (M) is obtained by mixing a polyester resin with additives as needed.

[0067] Specifically, a polyester resin is first added to a hydrophilic solvent containing water and stirred to prepare an aqueous dispersion of the polyester resin. The hydrophilic solvent is not particularly limited, but examples include alcohol-based solvents such as methanol, ethanol, 2-propanol, and 1,2-propanediol; glycol ether-based solvents such as propylene glycol monomethyl ether, ethyl cellosolve, and n-butyl cellosolve; and ketone-based solvents such as acetone and methyl ethyl ketone.

[0068] Next, an additive is added to the polyester resin aqueous dispersion and further stirred to prepare an aqueous dispersion of composition (M). Then, the aqueous dispersion of composition (M) is heated and dried to volatilize the hydrophilic solvent containing water, thereby obtaining composition (M). The drying conditions are not particularly limited as long as the temperature and time are such that the water and hydrophilic solvent used volatilize.

[0069] 2.2.Artificial leather (composition) The artificial leather 1 according to this embodiment comprises a base layer 2 containing polyester fabric, an intermediate layer 3, and a surface layer 4 (see Figure 1). Preferably, the base layer 2, the intermediate layer 3, and the surface layer 4 are laminated in this order to form the artificial leather 1.

[0070] The base layer 2 includes a polyester fabric, as described above. The polyester fabric is not particularly limited, but examples include knitted fabrics, woven fabrics, nonwoven fabrics, and special nonwoven fabrics containing polyester resin.

[0071] Intermediate layer 3 contains a polyester resin composition for intermediate layer 3. The polyester resin composition for intermediate layer 3 contains the composition (M) described above. The Tg of the polyester resin contained in the polyester resin composition for intermediate layer 3 is preferably 0°C or higher and 40°C or lower.

[0072] The polyester resin composition for the intermediate layer 3 may contain one type of polyester resin or two or more types. Furthermore, if the polyester resin composition for the intermediate layer 3 contains two or more types of polyester resin, each of the polyester resins may be mixed in any proportion.

[0073] The intermediate layer 3 may be a single layer or two or more layers. If the intermediate layer 3 is two or more layers, each layer of the intermediate layer 3 may be formed from the same polyester resin composition for the intermediate layer 3 or from different polyester resin compositions for the intermediate layer 3.

[0074] The epidermal layer 4 contains a polyester resin composition for the epidermal layer 4. The polyester resin composition for the epidermal layer 4 includes the composition (M) described above. The Tg of the polyester resin contained in the polyester resin composition for the epidermal layer 4 is preferably 25°C or higher and 55°C or lower.

[0075] The polyester resin composition for the epidermal layer 4 may contain one type of polyester resin or two or more types. Furthermore, if the polyester resin composition for the epidermal layer 4 contains two or more types of polyester resin, each of the polyester resins may be mixed in any proportion.

[0076] The epidermal layer 4 may be a single layer or two or more layers. If the epidermal layer 4 is two or more layers, each layer of the epidermal layer 4 may be formed from the same polyester resin composition for the epidermal layer 4.

[0077] Preferably, the Tg of the polyester resin in the polyester resin composition for the intermediate layer 3 is lower than the Tg of the polyester resin in the polyester resin composition for the surface layer 4. In this case, the adhesion between the intermediate layer 3 and the base layer 2 and the surface layer 4 can be improved, and the texture of the artificial leather 1 can be improved.

[0078] By comprising a base layer 2, an intermediate layer 3, and a surface layer 4 having the above-described characteristics as constituent elements, the artificial leather 1 can achieve improved abrasion resistance and heat resistance, as well as a good texture.

[0079] The artificial leather 1 may further include layers (hereinafter also referred to as intervening layers) different from the base layer 2, intermediate layer 3, and surface layer 4 between the base layer 2 and the intermediate layer 3, and between the intermediate layer 3 and the surface layer 4 (not shown). Such layers are not particularly limited, but examples include porous layers, foamed layers, adhesive layers, etc. Furthermore, the artificial leather 1 may further include a surface treatment layer (not shown) on the surface of the surface layer 4 opposite to the surface facing the intermediate layer 3.

[0080] Preferably, each component of the artificial leather 1 contains primarily polyester. In this case, since the artificial leather 1 is composed of a single material and is monomaterial, it can be easily recycled.

[0081] (Manufacturing method) The method for manufacturing the artificial leather 1 according to this embodiment comprises the steps of forming an epidermal layer 4 on a release substrate, forming an intermediate layer 3 on the epidermal layer 4, pressing the intermediate layer 3 and the base material layer 2 together, and peeling the release substrate from the epidermal layer 4.

[0082] The step of forming the surface layer 4 on the release substrate (hereinafter also referred to as step (1)) is a step of applying an aqueous dispersion of the polyester resin composition for the surface layer 4 onto the release substrate and drying it.

[0083] The release substrate is not particularly limited, but examples include paper coated on its surface with silicone, synthetic resin, etc.; synthetic resin films such as polypropylene and polyethylene; and composite substrates in which a synthetic resin film such as polypropylene and polyethylene is laminated to the surface of paper.

[0084] An aqueous dispersion of the polyester resin composition for the epidermal layer 4 can be obtained, for example, by adding the polyester resin composition for the epidermal layer 4 to water or water containing a hydrophilic organic solvent and stirring.

[0085] The method for applying the aqueous dispersion of the polyester resin composition for the surface layer 4 is not particularly limited, but examples include bar coating, dip coating, spray coating, and spin coating. The drying conditions are not particularly limited as long as the temperature and time are sufficient for the water and hydrophilic solvent used to evaporate.

[0086] Furthermore, if you wish to form two or more layers of epidermal layer 4, you can do so by repeatedly performing step (1).

[0087] The step of forming the intermediate layer 3 on the epidermal layer 4 (hereinafter also referred to as step (2)) is the step of applying an aqueous dispersion of the polyester resin composition for the intermediate layer 3 onto the epidermal layer 4 and drying it.

[0088] The aqueous dispersion of the polyester resin composition for the intermediate layer 3 is obtained in the same manner as the method for producing the aqueous dispersion of the polyester resin composition for the surface layer 4.

[0089] The application method and drying conditions for the aqueous dispersion of the polyester resin composition for the intermediate layer 3 can be carried out in the same manner as for the aqueous dispersion of the polyester resin composition for the surface layer 4.

[0090] Furthermore, when forming two or more intermediate layers 3, the process (2) can be repeated in the same manner as in the process (1) described above to form two or more intermediate layers 3.

[0091] The process of pressing the intermediate layer 3 and the base material layer 2 together (hereinafter also referred to as process (3)) is the process of placing the base material layer 2 on top of the intermediate layer 3 and pressing the intermediate layer 3 and the base material layer 2 together.

[0092] The crimping conditions are not particularly limited, but for example, the pressure is 0.1 MPa or more and 10 MPa or less, the temperature is 20°C or more and 200°C or less, and the time is 0.1 seconds or more and 10 seconds or less.

[0093] The step of peeling the release agent from the epidermal layer 4 (hereinafter also referred to as step (4)) is a step of peeling the release agent from the epidermal layer 4 to form artificial leather 1.

[0094] The method for manufacturing artificial leather 1 may include steps (1) to (4) above, as well as steps for forming an intervening layer and a surface treatment layer. The step for forming the intervening layer may be carried out between steps (1) and (2), and between steps (2) and (3). The step for forming the surface treatment layer may be carried out after step (4). The steps for forming the intervening layer and the surface treatment layer are not particularly limited, but may be carried out, for example, by applying a liquid member and drying it, or by overlapping and pressing sheet-like or film-like members.

[0095] 3. Appearance As is clear from the embodiments described above, this disclosure includes the following aspects. In the following, reference numerals are enclosed in parentheses solely to indicate their correspondence with the embodiments.

[0096] The composition (M) according to the first embodiment is a composition (M) contained in artificial leather (1), and contains a polyester resin having a metal sulfonate group. The polyester resin contains polycarboxylic acid residues including metal sulfonate group-containing polycarboxylic acid residues and aromatic polycarboxylic acid residues, and polyhydric alcohol residues including ethylene glycol residues as structural units. The content of metal sulfonate group-containing polycarboxylic acid residues is 0.5 mol% to 10 mol% of the total amount of polycarboxylic acid residues. The content of aromatic polycarboxylic acid residues is 50 mol% to 99.5 mol% of the total amount of polycarboxylic acid residues. The polyester resin has a glass transition temperature of 0°C to 55°C and an acid value of 20 mgKOH / g or less.

[0097] According to this embodiment, high abrasion resistance, high heat resistance, and a good texture can be achieved for the artificial leather (1).

[0098] In the second embodiment, composition (M) further comprises, in the first embodiment, a polyester resin comprising at least one selected from the group consisting of aliphatic polycarboxylic acid residues and aliphatic polyalcohol residues as a structural unit.

[0099] According to this embodiment, the glass transition temperature of the polyester resin can be adjusted, and a better texture can be achieved for the artificial leather (1).

[0100] In the third embodiment of composition (M), the content of aliphatic polycarboxylic acid residues is greater than 0 mol% and 40 mol% or less relative to the total amount of polycarboxylic acid residues.

[0101] According to this embodiment, the glass transition temperature of the polyester resin can be adjusted, and an even better texture can be achieved for the artificial leather (1).

[0102] In the composition (M) according to the fourth embodiment, the content of aliphatic polyhydric alcohol residues is greater than 0 mol% and less than or equal to 50 mol% of the total amount of polyhydric alcohol residues, as per the second or third embodiment.

[0103] According to this embodiment, the glass transition temperature of the polyester resin can be adjusted, and an even better texture can be achieved for the artificial leather (1).

[0104] The artificial leather (1) according to the fifth embodiment comprises a base layer (2) containing a polyester fabric, an intermediate layer (3) containing a polyester resin composition for the intermediate layer (3), and a surface layer (4) containing a polyester resin composition for the surface layer (4). Each of the polyester resin composition for the intermediate layer (3) and the polyester resin composition for the surface layer (4) contains a composition (M) according to any one of the first to fourth embodiments.

[0105] According to this embodiment, high wear resistance, high heat resistance, and a good texture can be achieved.

[0106] In the sixth embodiment of the artificial leather (1), in the fifth embodiment, the glass transition temperature of the polyester resin contained in the polyester resin composition for the intermediate layer (3) is 0°C or higher and 40°C or lower. The glass transition temperature of the polyester resin contained in the polyester resin composition for the surface layer (4) is 25°C or higher and 55°C or lower.

[0107] According to this embodiment, high wear resistance, high heat resistance, and a good texture can be achieved.

[0108] In the seventh embodiment of the artificial leather (1), in the fifth or sixth embodiment, the glass transition temperature of the polyester resin contained in the polyester resin composition for the intermediate layer (3) is lower than the glass transition temperature of the polyester resin contained in the polyester resin composition for the surface layer (4).

[0109] According to this embodiment, the adhesion of the intermediate layer (3) to the substrate layer (2) and the epidermal layer (4) can be improved.

[0110] The eighth embodiment of the method for manufacturing artificial leather (1) is a method for manufacturing artificial leather (1) in which a base layer (2) containing polyester fabric, an intermediate layer (3) containing a polyester resin composition for the intermediate layer (3), and a surface layer (4) containing a polyester resin composition for the surface layer (4) are laminated in this order. Each of the polyester resin composition for the intermediate layer (3) and the polyester resin composition for the surface layer (4) contains a polyester resin having a metal sulfonate group. The method for manufacturing artificial leather (1) comprises the steps of forming a surface layer (4) by applying an aqueous dispersion of the polyester resin composition for the surface layer (4) onto a release substrate and drying it, forming an intermediate layer (3) by applying an aqueous dispersion of the polyester resin composition for the intermediate layer (3) onto the surface layer (4) and drying it, stacking a base layer (2) on the intermediate layer (3) and pressing the intermediate layer (3) and the base layer (2) together, and peeling the release substrate from the surface layer (4).

[0111] According to this embodiment, it is possible to manufacture artificial leather (1) that has high abrasion resistance, high heat resistance, and a good texture. [Examples]

[0112] The present disclosure will be described in detail below with reference to examples. However, the present disclosure is not limited in any way to the following examples.

[0113] 1. Polyester resin composition 1.1. Polyester resin (1) Synthesis of polyester resin A 1000 mL reaction vessel equipped with a stirrer, nitrogen gas inlet, thermometer, rectification column, and cooling condenser was prepared. The components shown in Table 1 and potassium titanium oxalate as a catalyst were added to this reaction vessel in the proportions shown in Table 1 and stirred to obtain a mixture. This mixture was heated to 200°C under atmospheric pressure and a nitrogen atmosphere while being stirred, and then gradually heated to 250°C over 4 hours to complete the ester formation reaction. Next, at a temperature of 250°C, the pressure was gradually reduced to 0.67 hPa (0.5 mmHg), and the mixture was held at that state for 2 hours to carry out the polycondensation reaction. A polyester resin was obtained as a result.

[0114] (2) Physical property evaluation (Glass transition temperature) The glass transition temperature of the polyester resin obtained above was determined from the results of differential scanning calorimetry using a differential scanning calorimetry analyzer (manufactured by Rigaku Corporation, model number: DSCvesta) in accordance with JIS K 7121:2012.

[0115] (Acid value) The acid value of the polyester resin obtained above was determined from the results of titration using a potassium hydroxide ethanol solution, in accordance with JIS K 0070:1992.

[0116] (Weight average molecular weight) The weight-average molecular weight of the polyester resin obtained above was determined from the results of gel permeation chromatography (polystyrene equivalent). The details of the measurement conditions are shown below.

[0117] <Measurement conditions> Measurement device: Agilent Technologies, Part Number: 1260 Infinity II Column: Manufactured by Tosoh Corporation, Part Number: TSKgel α-3000 Guard column: Manufactured by Tosoh Corporation, Part number: TSKgel guardcolumn α Sample concentration: Dilute with dimethylacetamide to a polyester resin concentration of 0.5% by mass. Mobile phase solvent: Dimethylacetamide Flow rate: 0.6mL / min. Detector: Differential refractive index detector Column temperature: 40°C.

[0118] [Table 1]

[0119] 1.2. Preparation of Polyester Resin Aqueous Dispersion A 1000 mL container equipped with a stirrer and thermometer was prepared. In this container, 100 parts by mass of the polyester resin obtained above, 40 parts by mass of n-butyl cellosolve, and 260 parts by mass of water were mixed and kept at a temperature of 85-90°C for 2 hours while stirring to obtain an aqueous dispersion of polyester resin with a polyester resin concentration of 25% by mass.

[0120] 1.3. Preparation of aqueous dispersions of polyester resin compositions A 200 mL container equipped with a stirrer was prepared. 100 parts by mass of the above-mentioned aqueous polyester resin dispersion, 3 parts by mass of a polycarbodiimide crosslinking agent (manufactured by Nisshinbo Chemical Co., Ltd., product name: Carbodilite SV-02), and 5 parts by mass of an aqueous pigment paste (manufactured by Daikyo Chemical Industry Co., Ltd., product name: WUB BLACK 1C058) were added and stirred to obtain a mixture. 3 parts by mass of a thickening agent (manufactured by ADEKA, product name: Adekanol UH-541VF) were further added to this mixture and stirred to obtain an aqueous dispersion of the polyester resin composition.

[0121] 2.Artificial leather 2.1. Manufacturing of artificial leather (Examples 2-1, 2-4, 2-7 to 2-16, Comparative Examples 2-1 to 2-2) The polyester resin compositions obtained above were used in the combinations shown in Table 2 to produce artificial leather for Examples 2-1, 2-4, and 2-7 to 2-16, as well as Comparative Examples 2-1 to 2-2. Specifically, first, an aqueous dispersion of the polyester resin composition for the surface layer A was applied to release paper (manufactured by Ajinomoto Co., Ltd., product name: DN-TP APT DE-90) as a release substrate, so that the film thickness before drying was 250 μm. Then, the surface layer A was formed by drying at 100°C for 90 seconds, and then again at 120°C for 90 seconds.

[0122] Next, an aqueous dispersion of the polyester resin composition for the intermediate layer A was applied to the formed surface layer A so that the pre-drying film thickness was 250 μm. Then, the intermediate layer A was formed by drying at 100°C for 90 seconds, followed by further drying at 120°C for 90 seconds.

[0123] Next, a polyester knitted fabric (tricot fabric, 100% polyester content) was placed on top of the formed intermediate layer A as a base layer, and pressed using a hot press machine under conditions of 0.1 MPa, 80°C, and 1 second. After pressing, the release agent was peeled off to produce artificial leather.

[0124] (Examples 2-2 to 2-3) The polyester resin compositions obtained above were used in the combinations shown in Table 2 to produce the artificial leathers of Examples 2-2 to 2-3. Specifically, first, an aqueous dispersion of the polyester resin composition for the surface layer A was applied to release paper (manufactured by Ajinomoto Co., Ltd., product name: DN-TP APT DE-90) as a release substrate, so that the film thickness before drying was 125 μm. Then, the surface layer A was formed by drying at 100°C for 90 seconds, and then drying again at 120°C for 90 seconds.

[0125] Next, an aqueous dispersion of the polyester resin composition for skin layer B was applied to the formed skin layer A so that the pre-drying film thickness was 125 μm. Then, after drying at 100°C for 90 seconds, skin layer B was formed by further drying at 120°C for 90 seconds.

[0126] Next, an aqueous dispersion of the polyester resin composition for the intermediate layer A was applied to the formed surface layer B so that the pre-drying film thickness was 250 μm. Then, the intermediate layer A was formed by drying at 100°C for 90 seconds, followed by further drying at 120°C for 90 seconds.

[0127] Next, a polyester knitted fabric (tricot fabric, 100% polyester content) was placed on top of the formed intermediate layer A as a base layer, and pressed using a hot press machine under conditions of 0.1 MPa, 80°C, and 1 second. After pressing, the release agent was peeled off to produce artificial leather.

[0128] (Examples 2-5 to 2-6) The polyester resin compositions obtained above were used in the combinations shown in Table 2 to produce the artificial leathers of Examples 2-5 to 2-6. Specifically, first, an aqueous dispersion of the polyester resin composition for the surface layer A was applied to release paper (manufactured by Ajinomoto Co., Ltd., product name: DN-TP APT DE-90) as a release substrate, so that the film thickness before drying was 250 μm. Then, the surface layer A was formed by drying at 100°C for 90 seconds, and then again at 120°C for 90 seconds.

[0129] Next, an aqueous dispersion of the polyester resin composition for the intermediate layer A was applied to the formed surface layer A so that the pre-drying film thickness was 125 μm. Then, the intermediate layer A was formed by drying at 100°C for 90 seconds, followed by further drying at 120°C for 90 seconds.

[0130] Next, an aqueous dispersion of the polyester resin composition for intermediate layer B was applied onto the formed intermediate layer A so that the pre-drying film thickness was 125 μm. Then, intermediate layer B was formed by drying at 100°C for 90 seconds, followed by further drying at 120°C for 90 seconds.

[0131] Next, a polyester knitted fabric (tricot fabric, 100% polyester content) was placed on top of the formed intermediate layer B as a base layer, and pressed using a hot press machine under conditions of 0.1 MPa, 80°C, and 1 second. After pressing, the release agent was peeled off to produce artificial leather.

[0132] 2.2. Evaluation (Abrasion resistance) The artificial leather prepared as described above was subjected to abrasion testing according to the JIS-L-1096E method (Martindale method). For the abrasion test, SDL Atlas's "SM25 Wool Abradant Fabric" was used as the abrasion cloth, and the surface layer of the artificial leather was abraded under a pressure load of 9 kPa and 100,000 cycles. The abrasion resistance of the artificial leather was evaluated by visually observing the change in the appearance of the surface layer of the artificial leather after the abrasion test, according to the following criteria.

[0133] <Evaluation Criteria> A: There were no tears in the epidermal or intermediate layers of the artificial leather, and no exposure of the base layer was observed. B: Part of the epidermal and intermediate layers of the artificial leather are torn, and part of the base layer is exposed. C: The epidermal and intermediate layers of the artificial leather are moderately torn, and the base layer is moderately exposed. D: The outer layer and middle layer of the artificial leather were largely torn, and the base layer was significantly exposed.

[0134] (Texture) The texture of the artificial leather produced as described above was evaluated by touching the surface layer of the artificial leather with the hand and using the following criteria.

[0135] <Evaluation Criteria> A: It has a very soft texture. B: Soft to the touch C: The texture is slightly hard. D: It has a hard texture.

[0136] (Heat resistance) The heat resistance of the artificial leather prepared as described above was evaluated by placing the artificial leather in a 120°C hot air dryer and leaving it for 10 minutes. The surface layer of the artificial leather was then visually inspected, and the change in gloss value was observed, according to the following criteria. The gloss value was measured on the surface layer of the artificial leather using a digital angle-shifting gloss meter (Suga Test Instruments Co., Ltd., model UGV-5D, incident angle 60°, receiving angle 60°).

[0137] <Evaluation Criteria> A: No visible change in appearance was observed, and the change in gloss value was 1.0 or less. B: A slight change in glossiness is observed visually, and the change in gloss value is 1.5 or less. C: A change in glossiness is observed visually, and the change in gloss value is 1.6 or more. D: A significant change in glossiness was observed visually, and the change in gloss value was 2.1 or higher.

[0138] (Hydrolysis resistance) The hydrolysis resistance of the artificial leather prepared as described above was evaluated by visually observing the changes in the appearance of the surface layer of the artificial leather after it had been left standing for 35 days in a constant temperature and humidity chamber set to 75°C and 95%RH, according to the following criteria.

[0139] <Evaluation Criteria> A: No change was observed in the appearance of the surface layer of the artificial leather. B: Discoloration was observed on a portion of the surface of the artificial leather's outer layer. C: Discoloration was observed on most of the surface of the artificial leather's outer layer. D: Delamination was observed in the artificial leather.

[0140] [Table 2] [Explanation of symbols]

[0141] 1 Artificial leather 2 Base material layer 3. Middle Class 4 Epidermal layer

Claims

1. A polyester resin composition contained in artificial leather comprising a base layer, an intermediate layer, and an outer layer, The polyester resin composition comprises a polyester resin composition for the intermediate layer contained in the intermediate layer and a polyester resin composition for the surface layer contained in the surface layer. Each of the aforementioned polyester resin composition for the intermediate layer and the aforementioned polyester resin composition for the surface layer comprises a polyester resin having a metal sulfonate group. The polyester resin contains, as structural units, polycarboxylic acid residues including metal sulfonate group-containing polycarboxylic acid residues and aromatic polycarboxylic acid residues, and polyhydric alcohol residues including ethylene glycol residues. The content of the metal sulfonate group-containing polycarboxylic acid residue is 0.5 mol% or more and 10 mol% or less relative to the total amount of the polycarboxylic acid residue. The content of the aromatic polycarboxylic acid residue is 50 mol% or more and 99.5 mol% or less relative to the total amount of the polycarboxylic acid residue. The aforementioned polyester resin has an acid value of 20 mg KOH / g or less. The glass transition temperature of the polyester resin contained in the intermediate layer polyester resin composition is 0°C or higher and 40°C or lower. The glass transition temperature of the polyester resin contained in the polyester resin composition for the surface layer is 25°C or higher and 55°C or lower. Polyester resin composition.

2. The glass transition temperature of the polyester resin contained in the intermediate layer polyester resin composition is lower than the glass transition temperature of the polyester resin contained in the surface layer polyester resin composition. The polyester resin composition according to claim 1.

3. A polyester resin composition contained in artificial leather comprising a base layer, an intermediate layer, and an outer layer, The polyester resin composition comprises a polyester resin composition for the intermediate layer contained in the intermediate layer and a polyester resin composition for the surface layer contained in the surface layer. Each of the aforementioned polyester resin composition for the intermediate layer and the aforementioned polyester resin composition for the surface layer comprises a polyester resin having a metal sulfonate group. The polyester resin contains, as structural units, polycarboxylic acid residues including metal sulfonate group-containing polycarboxylic acid residues and aromatic polycarboxylic acid residues, and polyhydric alcohol residues including ethylene glycol residues. The content of the metal sulfonate group-containing polycarboxylic acid residue is 0.5 mol% or more and 10 mol% or less relative to the total amount of the polycarboxylic acid residue. The content of the aromatic polycarboxylic acid residue is 50 mol% or more and 99.5 mol% or less relative to the total amount of the polycarboxylic acid residue. The aforementioned polyester resin has a glass transition temperature of 0°C to 55°C and an acid value of 20 mg KOH / g or less. The glass transition temperature of the polyester resin contained in the intermediate layer polyester resin composition is lower than the glass transition temperature of the polyester resin contained in the surface layer polyester resin composition. Polyester resin composition.

4. The polyester resin further comprises at least one selected from the group consisting of aliphatic polycarboxylic acid residues and aliphatic polyalcohol residues as a structural unit. A polyester resin composition according to any one of claims 1 to 3.

5. The content of the aliphatic polycarboxylic acid residue is greater than 0 mol% and 40 mol% or less relative to the total amount of the polycarboxylic acid residue. The polyester resin composition according to claim 4.

6. The content of the aliphatic polyhydric alcohol residue is greater than 0 mol% and less than or equal to 50 mol% of the total amount of the polyhydric alcohol residue. The polyester resin composition according to claim 4.

7. Artificial leather comprising a base layer, an intermediate layer and an epidermal layer, The base layer includes polyester fabric, The intermediate layer comprises a polyester resin composition for the intermediate layer. The aforementioned epidermal layer comprises a polyester resin composition for epidermal layers. Each of the aforementioned polyester resin composition for the intermediate layer and the aforementioned polyester resin composition for the surface layer comprises a polyester resin having a metal sulfonate group. The polyester resin contains, as structural units, polycarboxylic acid residues including metal sulfonate group-containing polycarboxylic acid residues and aromatic polycarboxylic acid residues, and polyhydric alcohol residues including ethylene glycol residues. The content of the metal sulfonate group-containing polycarboxylic acid residue is 0.5 mol% or more and 10 mol% or less relative to the total amount of the polycarboxylic acid residue. The content of the aromatic polycarboxylic acid residue is 50 mol% or more and 99.5 mol% or less relative to the total amount of the polycarboxylic acid residue. The aforementioned polyester resin has an acid value of 20 mg KOH / g or less. The glass transition temperature of the polyester resin contained in the intermediate layer polyester resin composition is 0°C or higher and 40°C or lower. The glass transition temperature of the polyester resin contained in the polyester resin composition for the surface layer is 25°C or higher and 55°C or lower. Artificial leather.

8. Artificial leather comprising a base layer, an intermediate layer and an epidermal layer, The base layer includes polyester fabric, The intermediate layer comprises a polyester resin composition for the intermediate layer. The aforementioned epidermal layer comprises a polyester resin composition for epidermal layers. Each of the aforementioned polyester resin composition for the intermediate layer and the aforementioned polyester resin composition for the surface layer comprises a polyester resin having a metal sulfonate group. The polyester resin contains, as structural units, polycarboxylic acid residues including metal sulfonate group-containing polycarboxylic acid residues and aromatic polycarboxylic acid residues, and polyhydric alcohol residues including ethylene glycol residues. The content of the metal sulfonate group-containing polycarboxylic acid residue is 0.5 mol% or more and 10 mol% or less relative to the total amount of the polycarboxylic acid residue. The content of the aromatic polycarboxylic acid residue is 50 mol% or more and 99.5 mol% or less relative to the total amount of the polycarboxylic acid residue. The aforementioned polyester resin has a glass transition temperature of 0°C to 55°C and an acid value of 20 mg KOH / g or less. The glass transition temperature of the polyester resin contained in the intermediate layer polyester resin composition is lower than the glass transition temperature of the polyester resin contained in the surface layer polyester resin composition. Artificial leather.

9. A method for manufacturing artificial leather comprising a base layer containing polyester fabric, an intermediate layer containing a polyester resin composition for the intermediate layer, and a surface layer containing a polyester resin composition for the surface layer, laminated in this order, Each of the aforementioned polyester resin composition for the intermediate layer and the aforementioned polyester resin composition for the surface layer comprises a polyester resin having a metal sulfonate group. The polyester resin contains, as structural units, polycarboxylic acid residues including metal sulfonate group-containing polycarboxylic acid residues and aromatic polycarboxylic acid residues, and polyhydric alcohol residues including ethylene glycol residues. The content of the metal sulfonate group-containing polycarboxylic acid residue is 0.5 mol% or more and 10 mol% or less relative to the total amount of the polycarboxylic acid residue. The content of the aromatic polycarboxylic acid residue is 50 mol% or more and 99.5 mol% or less relative to the total amount of the polycarboxylic acid residue. The aforementioned polyester resin has an acid value of 20 mg KOH / g or less. The glass transition temperature of the polyester resin contained in the intermediate layer polyester resin composition is 0°C or higher and 40°C or lower. The glass transition temperature of the polyester resin contained in the aforementioned polyester resin composition for the surface layer is 25°C or higher and 55°C or lower. The process involves applying an aqueous dispersion of the polyester resin composition for the surface layer onto a release substrate and drying it to form the surface layer, The process of forming the intermediate layer by applying an aqueous dispersion of the polyester resin composition for the intermediate layer onto the surface layer and drying it, A step of placing the base material layer on the intermediate layer and pressing the intermediate layer and the base material layer together, The process includes a step of peeling the release substrate from the surface layer. A method for manufacturing artificial leather.

10. A method for manufacturing artificial leather comprising a base layer containing polyester fabric, an intermediate layer containing a polyester resin composition for the intermediate layer, and a surface layer containing a polyester resin composition for the surface layer, laminated in this order, Each of the aforementioned polyester resin composition for the intermediate layer and the aforementioned polyester resin composition for the surface layer comprises a polyester resin having a metal sulfonate group. The polyester resin contains, as structural units, polycarboxylic acid residues including metal sulfonate group-containing polycarboxylic acid residues and aromatic polycarboxylic acid residues, and polyhydric alcohol residues including ethylene glycol residues. The content of the metal sulfonate group-containing polycarboxylic acid residue is 0.5 mol% or more and 10 mol% or less relative to the total amount of the polycarboxylic acid residue. The content of the aromatic polycarboxylic acid residue is 50 mol% or more and 99.5 mol% or less relative to the total amount of the polycarboxylic acid residue. The aforementioned polyester resin has a glass transition temperature of 0°C to 55°C and an acid value of 20 mg KOH / g or less. The glass transition temperature of the polyester resin contained in the intermediate layer polyester resin composition is lower than the glass transition temperature of the polyester resin contained in the surface layer polyester resin composition. The process involves applying an aqueous dispersion of the polyester resin composition for the surface layer onto a release substrate and drying it to form the surface layer, The process of forming the intermediate layer by applying an aqueous dispersion of the polyester resin composition for the intermediate layer onto the surface layer and drying it, A step of placing the base material layer on the intermediate layer and pressing the intermediate layer and the base material layer together, The process includes a step of peeling the release substrate from the surface layer. A method for manufacturing artificial leather.

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