EP4324979A2 - Kunstleder - Google Patents

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Publication number
EP4324979A2
EP4324979A2 EP23190797.3A EP23190797A EP4324979A2 EP 4324979 A2 EP4324979 A2 EP 4324979A2 EP 23190797 A EP23190797 A EP 23190797A EP 4324979 A2 EP4324979 A2 EP 4324979A2
Authority
EP
European Patent Office
Prior art keywords
resin
artificial leather
mass
component
fibers
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP23190797.3A
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English (en)
French (fr)
Inventor
Kazuya Kawai
Aki HATANAKA
Keiichiro SAKATA
Hidehiro Yamaguchi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Asahi Kasei Corp
Asahi Chemical Industry Co Ltd
Original Assignee
Asahi Kasei Corp
Asahi Chemical Industry Co Ltd
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Publication date
Application filed by Asahi Kasei Corp, Asahi Chemical Industry Co Ltd filed Critical Asahi Kasei Corp
Publication of EP4324979A2 publication Critical patent/EP4324979A2/de
Pending legal-status Critical Current

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    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06N—WALL, FLOOR, OR LIKE COVERING MATERIALS, e.g. LINOLEUM, OILCLOTH, ARTIFICIAL LEATHER, ROOFING FELT, CONSISTING OF A FIBROUS WEB COATED WITH A LAYER OF MACROMOLECULAR MATERIAL; FLEXIBLE SHEET MATERIAL NOT OTHERWISE PROVIDED FOR
    • D06N3/00—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof
    • D06N3/12—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof with macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds, e.g. gelatine proteins
    • D06N3/14—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof with macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds, e.g. gelatine proteins with polyurethanes
    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06N—WALL, FLOOR, OR LIKE COVERING MATERIALS, e.g. LINOLEUM, OILCLOTH, ARTIFICIAL LEATHER, ROOFING FELT, CONSISTING OF A FIBROUS WEB COATED WITH A LAYER OF MACROMOLECULAR MATERIAL; FLEXIBLE SHEET MATERIAL NOT OTHERWISE PROVIDED FOR
    • D06N3/00—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof
    • D06N3/0002—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof characterised by the substrate
    • D06N3/0004—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof characterised by the substrate using ultra-fine two-component fibres, e.g. island/sea, or ultra-fine one component fibres (< 1 denier)
    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06N—WALL, FLOOR, OR LIKE COVERING MATERIALS, e.g. LINOLEUM, OILCLOTH, ARTIFICIAL LEATHER, ROOFING FELT, CONSISTING OF A FIBROUS WEB COATED WITH A LAYER OF MACROMOLECULAR MATERIAL; FLEXIBLE SHEET MATERIAL NOT OTHERWISE PROVIDED FOR
    • D06N3/00—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof
    • D06N3/0002—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof characterised by the substrate
    • D06N3/0006—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof characterised by the substrate using woven fabrics
    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06N—WALL, FLOOR, OR LIKE COVERING MATERIALS, e.g. LINOLEUM, OILCLOTH, ARTIFICIAL LEATHER, ROOFING FELT, CONSISTING OF A FIBROUS WEB COATED WITH A LAYER OF MACROMOLECULAR MATERIAL; FLEXIBLE SHEET MATERIAL NOT OTHERWISE PROVIDED FOR
    • D06N3/00—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof
    • D06N3/0002—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof characterised by the substrate
    • D06N3/0011—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof characterised by the substrate using non-woven fabrics
    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06N—WALL, FLOOR, OR LIKE COVERING MATERIALS, e.g. LINOLEUM, OILCLOTH, ARTIFICIAL LEATHER, ROOFING FELT, CONSISTING OF A FIBROUS WEB COATED WITH A LAYER OF MACROMOLECULAR MATERIAL; FLEXIBLE SHEET MATERIAL NOT OTHERWISE PROVIDED FOR
    • D06N3/00—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof
    • D06N3/04—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof with macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06N—WALL, FLOOR, OR LIKE COVERING MATERIALS, e.g. LINOLEUM, OILCLOTH, ARTIFICIAL LEATHER, ROOFING FELT, CONSISTING OF A FIBROUS WEB COATED WITH A LAYER OF MACROMOLECULAR MATERIAL; FLEXIBLE SHEET MATERIAL NOT OTHERWISE PROVIDED FOR
    • D06N3/00—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof
    • D06N3/12—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof with macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds, e.g. gelatine proteins
    • D06N3/14—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof with macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds, e.g. gelatine proteins with polyurethanes
    • D06N3/146—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof with macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds, e.g. gelatine proteins with polyurethanes characterised by the macromolecular diols used
    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06N—WALL, FLOOR, OR LIKE COVERING MATERIALS, e.g. LINOLEUM, OILCLOTH, ARTIFICIAL LEATHER, ROOFING FELT, CONSISTING OF A FIBROUS WEB COATED WITH A LAYER OF MACROMOLECULAR MATERIAL; FLEXIBLE SHEET MATERIAL NOT OTHERWISE PROVIDED FOR
    • D06N3/00—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof
    • D06N3/18—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof with two layers of different macromolecular materials
    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06N—WALL, FLOOR, OR LIKE COVERING MATERIALS, e.g. LINOLEUM, OILCLOTH, ARTIFICIAL LEATHER, ROOFING FELT, CONSISTING OF A FIBROUS WEB COATED WITH A LAYER OF MACROMOLECULAR MATERIAL; FLEXIBLE SHEET MATERIAL NOT OTHERWISE PROVIDED FOR
    • D06N3/00—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof
    • D06N3/18—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof with two layers of different macromolecular materials
    • D06N3/183—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof with two layers of different macromolecular materials the layers are one next to the other
    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06N—WALL, FLOOR, OR LIKE COVERING MATERIALS, e.g. LINOLEUM, OILCLOTH, ARTIFICIAL LEATHER, ROOFING FELT, CONSISTING OF A FIBROUS WEB COATED WITH A LAYER OF MACROMOLECULAR MATERIAL; FLEXIBLE SHEET MATERIAL NOT OTHERWISE PROVIDED FOR
    • D06N3/00—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof
    • D06N3/18—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof with two layers of different macromolecular materials
    • D06N3/186—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof with two layers of different macromolecular materials one of the layers is on one surface of the fibrous web and the other layer is on the other surface of the fibrous web

Definitions

  • the present invention relates to artificial leather which has excellent clarity of emboss patterns, and which does not use organic solvents during the production process and thus has a low environmental impact.
  • Artificial leather comprising a fiber sheet such as a nonwoven fabric (fibrous base material) and a polyurethane (PU) resin as primary materials exhibits excellent properties that are difficult to achieve with natural leather, including easy care, functionality and homogeneity, and it is therefore suitable for use in clothing, shoes and bags, as well as for upholstery materials and interior materials for seats in interiors, automobiles, aircraft and railway vehicles, or decorative materials such as ribbons or patch bases. Embossing of artificial leather surfaces can increase their design properties for use in such fields. However, thermal decomposition or heat shrinkage of the binder occurs due to heating during embossing, resulting in an indistinct emboss pattern.
  • PU polyurethane
  • One commonly employed method for producing artificial leather in the prior art is a method of impregnating a fiber sheet with an organic solvent solution of a PU resin, and then immersing it in a non-solvent for the PU resin (such as water or an organic solvent), for wet coagulation of the PU resin.
  • a non-solvent for the PU resin such as water or an organic solvent
  • the organic solvent used as the solvent for the polyurethane resin is a water-miscible organic solvent such as N,N-dimethylformamide, but because of the high toxicity of organic solvents for the human body and the environment, there is high demand for methods that do not employ organic solvents for production of artificial leather.
  • PTL 1 proposes different polycarbonate-based PU materials obtained by reaction between a diol having two hydroxyl groups at one end and polysiloxane on a side chain, two different copolymerized polycarbonate diols, an organic diisocyanate, and a chain extender, primarily for the purpose of improving the texture of synthetic leather.
  • the polycarbonate-based polyurethanes are dissolved in N,N-dimethylformamide, and an organic solvent is used during production of artificial leather, it is associated with the problems of high environmental impact and high toxicity for the human body.
  • PTL 2 proposes PU resins obtained by reaction between a polyol obtained by transesterification of a polycarbonate diol or polyester diol, a polyol having hydroxyl groups at both ends, an organic diisocyanate and a chain extender, for the purpose of preventing hardening of the sheet texture.
  • PU resins obtained by reaction between a polyol obtained by transesterification of a polycarbonate diol or polyester diol, a polyol having hydroxyl groups at both ends, an organic diisocyanate and a chain extender, for the purpose of preventing hardening of the sheet texture.
  • cohesive groups such as urethane bonds and urea bonds
  • embossing onto artificial leather obtained by attachment to the fiber sheets causes heat shrinkage, making it difficult to produce distinct emboss patterns.
  • Urethane resin structures have conventionally been identified by local structural analysis of the urethane resins themselves by NMR (for the constituent isocyanate, chain extender and polyol monomer), but no technique (method) has been known in the technical field of artificial leather for non-destructive evaluation of the motility of a urethane resin in its solid state with the urethane resin adhering to a polyester fiber sheet. Consequently, the prior art has not known the relationship between the motility of urethane resins added to artificial leather as binders, and the clarity of emboss patterns in the artificial leather.
  • the problem to be solved by the invention is to provide artificial leather having a low environmental impact, by not using organic solvents during the production process, and also exhibiting excellent clarity of emboss patterns.
  • the present invention provides the following.
  • the artificial leather of the invention has a low environmental impact since it does not employ an organic solvent during the production process, while it also has excellent clarity of emboss patterns, and it can therefore be suitably used for upholstery or interior materials for seats in interiors, automobiles, aircraft and railway vehicles, or for clothing products.
  • One embodiment of the invention is artificial leather comprising a nonwoven fabric made of ultrafine fibers having a mean single fiber diameter of 0.3 ⁇ m to 7 ⁇ m, and water-dispersed polyurethane, wherein when the free induction decay (FID) signal in pulse NMR (solid echo method, proton observation, measuring temperature: 50°C) is fitted to two components: the S component (Gaussian component) and L component (Lorentz component), the spin-spin relaxation time T1 of the L component is 500 ⁇ sec to 800 ⁇ sec and the L component fraction Cl is 25% or greater and less than 55%.
  • FID free induction decay
  • artificial leather is that defined according to the Household Goods Quality Labeling Act as "leather comprising a special nonwoven fabric (mainly a fiber layer having a random three-dimensional spatial structure, impregnated with a PU resin or a polymer elastic solid of similar flexibility) as the base material".
  • leaf material mainly a fiber layer having a random three-dimensional spatial structure, impregnated with a PU resin or a polymer elastic solid of similar flexibility
  • artificial leather is classified as “smooth” having the grain side appearance of leather, or “napped” having a leather suede or velour outer appearance
  • the artificial leather of this embodiment is classified as “napped” (that is, suede-like artificial leather having a brushed-style outer appearance).
  • a suede-like outer appearance can be formed by buffing treatment (raising treatment) of the outer surface of the fiber layer (A) (the side that is to be the first outer surface of the artificial leather) using sandpaper or the like.
  • the outer surface of the artificial leather is the surface that is externally exposed when the artificial leather is used (the surface that contacts with the human body, in the case of a chair, for example) (see Fig. 1 and fiber layer (A), reference numeral 1).
  • the outer surface of the fiber layer (A) has raised or napped fibers produced by buffing, for example.
  • fiber web refers to the state before tangling of staple fibers
  • fiber sheet refers to the state after tangling and before PU resin filling
  • sheet refers to the state after PU resin filling and before dye finishing
  • artificial leather refers to the state of the product after dye finishing.
  • nonwoven fabric encompasses “fiber web”, “fiber sheet”, “sheet” and “artificial leather”
  • fibrous base material encompasses woven or knitted fabrics in addition to "nonwoven fabric”.
  • the fiber sheet (A) indicated by reference numeral 1 in Fig. 1 has a structure in which parts of the interlaced section of the fiber sheet comprising tangled polyester fibers are attached using a (poly)urethane resin as the binder, as shown in Fig. 3 .
  • a (poly)urethane resin is generally composed mainly of polyol amorphous components (soft segments held together by Van der Waals forces) that impart flexibility, softness, bendability, cold resistance, affinity and chemical resistance, while hard segments that are aggregated by hydrogen bonding of urethane (urea) bonds impart toughness, heat resistance, solvent resistance and elasticity.
  • the free induction decay (FID) signal in pulse NMR solid echo method, proton observation, measuring temperature: 50°C
  • S component Gaussian component
  • L component L component
  • the spin-spin relaxation time T1 of the L component is 500 ⁇ sec to 800 ⁇ sec and the L component fraction Cl is 25% or greater and less than 55%.
  • the component with low molecular mobility may be the polyester fiber, and the component with high molecular mobility may be the polyurethane resin.
  • the FID (free induction decay) decay curve is generally expressed by a function which is either Gaussian or Lorentzian, or Weibullian which is intermediate between them, depending on the active level of molecular motion in the sample.
  • the relaxation time of nuclear spin has several classifications, with some relaxation taking place efficiently by molecular chain movement at Larmor frequency-level speed, but for evaluating transverse relaxation time (T 2 ) during measurement of artificial leather, slow molecular motion is more sensitive to low frequencies, and the nuclear spin relaxes more efficiently with slower molecular motion and a longer correlation time, shortening the relaxation time. In other words, a component with longer relaxation time can be judged to be a component with high molecular mobility.
  • the decay curve of magnetization exhibits Gaussian decay, while the amorphous phase with high molecular mobility (a urethane resin soft segment, for example) exhibits Lorentzian decay for the decay curve.
  • the present inventors have found for the first time, that if the spin-spin relaxation time Tl of the L component is 500 ⁇ sec to 800 ⁇ sec and the L component fraction Cl is 25% to 54%, then heat shrinkage of the polyurethane resin during embossing is inhibited and emboss patterns in the resulting artificial leather are sufficiently distinct, and the present invention has been completed based on this finding.
  • the present inventors have confirmed that the high motility component fraction Cl and the proportion of PU resin with respect to the total mass of the sheet are in a strongly correlated relationship, and further that no artificial leather currently exists wherein the spin-spin relaxation time Tl of the L component is 500 ⁇ sec to 800 ⁇ sec.
  • the adhesion rate of the PU resin with respect to the total mass of the sheet fibers is preferably 15 mass% to 50 mass%, more preferably 22 mass% to 45 mass% and even more preferably 26 mass% to 40 mass%.
  • the proportion of PU resin with respect to the total mass of the sheet fibers affects the heat shrinking property of the polyurethane resin, and the consequent clarity of emboss patterns.
  • a PU resin proportion of 15 mass% or greater with respect to the total mass of the sheet fibers will allow the fibers to be satisfactorily held by the PU resin, so that mechanical strength including abrasion resistance on a level satisfying commercial demand can be more easily obtained.
  • a PU resin proportion of 50 mass% or lower with respect to the total mass of the sheet fibers, on the other hand, can result in artificial leather having a very soft hand quality and luxuriant feel.
  • the PU resin is preferably obtained by reacting a polymer polyol, an organic diisocyanate and a chain extender.
  • polymer diols to be used examples include polycarbonate-based, polyester-based, polyether-based, silicone-based and fluorine-based diols, as well as copolymers of any two or more of these.
  • the spin-spin relaxation time Tl of the L component is 500 ⁇ sec to 800 ⁇ sec, due to addition of an appropriately selected macromonomer component (having a side chain) as part of the short chain diol component, as a high molecular prepolymer component or chain extender, as described below.
  • polycarbonate-based or polyether-based diol From the viewpoint of hydrolysis resistance, it is preferred to use a polycarbonate-based or polyether-based diol, or a combination thereof. From the viewpoint of light fastness and heat resistance, polycarbonate-based or polyester-based diols, or their combinations, are preferred. From the viewpoint of cost competitiveness, a polyether-based or polyester-based diol, or a combination thereof, is preferred.
  • a polycarbonate-based diol can be produced by transesterification reaction of an alkylene glycol and a carbonic acid ester, or by reaction between phosgene or a chlorformic acid ester and an alkylene glycol.
  • alkylene glycols include straight-chain alkylene glycols such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol and 1,10-decanediol; branched alkylene glycols such as neopentyl glycol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol and 2-methyl-1,8-octanediol; alicyclic diols such as 1,4-cyclohexanediol; and aromatic diols such as bisphenol
  • Polyester-based diols include polyester diols obtained by condensation between any of various low molecular weight polyols and polybasic acids.
  • low molecular weight polyols include one or more selected from among ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,2-dimethyl-1,3-propanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,8-octanediol, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, cyclohexane-1,4-diol and cyclohexane-1,4-dimethanol.
  • An addition product of an alkylene oxide with bisphenol A may also be used.
  • polybasic acids include one or more selected from the group consisting of succinic acid, maleic acid, adipic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, phthalic acid, isophthalic acid, terephthalic acid and hexahydroisophthalic acid.
  • polyether-based diols examples include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and copolymer diols comprising their combinations.
  • the number-average molecular weight of the polymer diol is preferably 500 to 7000.
  • the number-average molecular weight is 500 or higher and more preferably 1500 or higher to help prevent hardening of the texture.
  • the number-average molecular weight is 7000 or lower to help maintain satisfactory strength of the PU resin.
  • Figs. 5 to 7 show examples of macromonomers.
  • a macromonomer is generally a monomer having an optional side chain introduced on the polymer main chain, the introduction of the side chain being able to prevent association between main chains.
  • the right hand side of Fig. 5 shows a state in which the side chains form a microphase-separated structure, helping to avoid association between the main chains. It should be noted, however, that in Fig. 5 the main chains are copolymerized with methyl methacrylate and are not macromonomers with two hydroxyl groups at one end, as used in the Examples and Comparative Examples.
  • Fig. 6 shows an example of a methyl methacrylate-based macromonomer as a polymer having two hydroxyl groups (a dihydroxyl group) at one end, and methyl methacrylate as the side chain.
  • the methyl methacrylate-based macromonomer may be "AA-6" by Toagosei Co., Ltd., having a Mn of 6,000.
  • Fig. 7 shows an example of a polydimethylsiloxane-based macromonomer, having two hydroxyl groups (a dihydroxyl group) at one end, and polydimethylsiloxane as the side chain.
  • the polydimethylsiloxane-based macromonomer may be "X-22-176DX" by Shin-Etsu Chemical Co., Ltd., having a molecular weight of 3000, or "X-22-177GX-A" by Shin-Etsu Chemical Co., Ltd., having a molecular weight of 14,000.
  • organic diisocyanates examples include aliphatic diisocyanates such as hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate and xylylene diisocyanate; and aromatic diisocyanates such as diphenylmethane diisocyanate and tolylene diisocyanate, and their combinations may also be used. Preferred among these from the viewpoint of light fastness are aliphatic diisocyanates such as hexamethylene diisocyanate, dicyclohexylmethane diisocyanate and isophorone diisocyanate.
  • hydrophilic agents include dialkylolalkanoic acids such as 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, 2,2-dimethylolheptanoic acid and 2,2-dimethyloloctanoic acid; amino acids such as glycine, alanine and valine; compounds with carboxyl groups such as tartaric acid; compounds with sulfo groups such as 3-(2,3-dihydroxypropoxy)-1-propanesulfonic acid and di(ethyleneglycol) sulfoisophthalate ester; and compounds with sulfamic acid groups such as N,N-bis(2-hydroxylethyl)sulfamic acid; or these same compounds as salts neutralized with a neutralizing agent as described below. Preferred for use among these are 2,2-dimethylolpropionic acid and 2,2-dimethylolbutanoic acid.
  • neutralizing agents examples include primary amines such as monomethylamine, monoethylamine, monobutylamine, monoethanolamine and 2-amino-2-methyl-1-propanol; secondary amines such as dimethylamine, diethylamine, dibutylamine, diethanolamine and N-methyldiethanolamine; and tertiary amines such as trimethylamine, triethylamine, dimethylethylamine and triethanolamine.
  • primary amines such as monomethylamine, monoethylamine, monobutylamine, monoethanolamine and 2-amino-2-methyl-1-propanol
  • secondary amines such as dimethylamine, diethylamine, dibutylamine, diethanolamine and N-methyldiethanolamine
  • tertiary amines such as trimethylamine, triethylamine, dimethylethylamine and triethanolamine.
  • triethylamine, monoethanolamine, diethanolamine and N-methyldiethanolamine are preferably used
  • Chain extenders to be used include amine-based chain extenders such as ethylenediamine and methylenebisaniline, or diol-based chain extenders such as ethylene glycol.
  • amine-based chain extenders such as ethylenediamine and methylenebisaniline
  • diol-based chain extenders such as ethylene glycol.
  • a polyamine obtained by reacting a polyisocyanate and water may also be used as a chain extender.
  • a water-dispersed PU resin as the PU resin to be added, from the viewpoint of eliminating the need for organic solvents to reduce the environmental impact.
  • Fig. 4 shows an example of a method for producing a water-dispersible polyurethane resin.
  • a water-dispersed polyurethane is produced by reacting a polymer polyol, a short chain diol, a hydrophilic agent and an isocyanate in a ketone-based solvent to synthesize a prepolymer in the first step, emulsifying the obtained prepolymer in water using a neutralizing agent in the second step, and reacting the prepolymer with a diamine as the chain extender and removing the ketone-based solvent, in the third step.
  • an appropriately selected macromonomer component (with a side chain) is used for synthesis of the prepolymer in first step, as mentioned above.
  • the method for producing the water-dispersed PU resin is not limited to the one illustrated in Fig. 4 .
  • the water-dispersed PU resin used may be a self-emulsifying PU resin containing hydrophilic groups within the PU molecules, or a forced-emulsifying PU resin in which the PU resin has been emulsified with an external emulsifying agent.
  • a crosslinking agent may also be used with the water-dispersed PU resin in order to improve the durability, including resistance to moist heat, abrasion resistance and hydrolysis resistance.
  • a crosslinking agent is also preferably added to improve the durability during jet dyeing, reduce loss of the fibers and obtain excellent surface quality.
  • the crosslinking agent may be an external crosslinking agent added as an addition component to the PU resin, or it may be a reactive group-introducing internal crosslinking agent that can produce a crosslinked structure beforehand within the PU resin structure.
  • the water-dispersed PU resin used in the artificial leather will generally have a crosslinked structure to provide dyeing resistance, it tends to be poorly soluble in organic solvents such as N,N-dimethylformamide. Therefore when observing a cross-section with an electron microscope, for example, if a resinous substance remains which lacks the form of the fibers after immersion of the artificial leather in N,N-dimethylformamide at room temperature for 12 hours to dissolve the PU resin, the resinous substance may be judged to be the water-dispersed PU resin.
  • the mean primary particle size of the polyurethane resin is the value obtained by measurement of the PU resin dispersion using a laser diffraction particle size distribution analyzer ("LA-920" by Horiba, Ltd.). If the mean primary particle size of the PU resin is 0.1 ⁇ m or greater, then the force with which the PU resin holds the fibers together in the fiber sheet (binding force) will be satisfactory, allowing artificial leather with excellent mechanical strength to be obtained. Limiting the mean primary particle size of the PU resin to 0.8 ⁇ m or smaller will inhibit aggregation and coarsening of the PU resin, which is advantageous for controlling the standard deviation of the surface PU resin area ratio to 20% or lower.
  • the mean primary particle size of the PU resin in the PU resin dispersion is 0.1 ⁇ m to 0.8 ⁇ m, then the fibers composing the artificial leather (surface layer) will be held together at more points, making it possible to obtain a soft hand quality (stiffness) and excellent mechanical strength (such as abrasion resistance), for example.
  • the PU resin is impregnated as an impregnating liquid in the form of a solution (dissolved in a solvent) or dispersion (water-dispersed).
  • the solid concentration of the water-dispersed PU resin dispersion may be 10 wt% to 35 wt%, for example, and is preferably 15 to 30 mass% and more preferably 15 to 25 mass%.
  • the impregnating liquid is prepared and impregnated into the fiber sheet so that the adhesion rate of the PU resin with respect to 100 mass% of the fiber sheet is 15 mass% to 50 mass%.
  • the impregnating liquid containing the PU resin may also contain additives such as stabilizers (ultraviolet absorbers and antioxidants), flame retardants, antistatic agents and pigments (such as carbon black), as necessary.
  • the total amount of additives in the artificial leather may be 0.1 to 10.0 parts by mass, 0.2 to 8.0 parts by mass or 0.3 to 6.0 parts by mass, for example, with respect to 100 parts by mass of the PU resin. Such additives become distributed in the PU resin of the artificial leather.
  • the values of the size of the PU resin and the mass ratio with respect to the fiber sheet mentioned herein are assumed to be the values including the additives (when used).
  • a step of adhering the hot water-soluble resin to the fiber sheet may be carried out before the water-dispersed PU resin dispersion is impregnated into the fiber sheet.
  • the method of adhering the hot water-soluble resin (such as a PVA resin) may be preparation of an aqueous solution of the hot water-soluble resin followed by impregnation of the fiber sheet with the water-soluble solution and drying.
  • Removing the hot water-soluble resin from the fiber sheet using hot water in the finishing-process steps or dyeing step can inhibit adhesion between the fibers and PU resin or can divide part of the continuous layer of the PU resin and form pores to micronize the state of adhesion of the PU resin, thus tending to improve the texture of the artificial leather.
  • the hot water-soluble resin may be a partially saponified PVA resin or completely saponified PVA resin. Since a completely saponified PVA resin tends to be less elutable into water at ordinary temperature (20°C) compared to a partially saponified PVA resin, a completely saponified PVA resin is preferably used as the hot water-soluble resin. From the viewpoint of inhibiting elution into water at ordinary temperature (20°C), the saponification degree of the completely saponified PVA resin is preferably 95 mol% or greater and more preferably 98 mol% or greater. In order to increase the permeability of the aqueous hot water-soluble resin solution during impregnation, the polymerization degree is preferably 1000 or lower and more preferably 700 or lower.
  • the fiber sheet 1 includes at least the fiber layer (A) 12, with the scrim 11 and fiber layer (B) 13 being optional and not essential elements.
  • the artificial leather of this embodiment may therefore be a single layer of the fiber layer (A), or two layers consisting of the fiber layer (A) and the scrim or fiber layer (B), or three layers consisting of the fiber layer (A), the scrim and the fiber layer (B).
  • the fiber layer (A) may be a single-layer fiber sheet which is sliced in half horizontally and then filled with the PU resin, as explained below.
  • the fiber sheet has a monolayer structure with no scrim. This will allow productivity to be increased by slicing in half horizontally.
  • the fiber sheet has a three-layer structure with a scrim as the intermediate layer.
  • a woven or knitted fabric scrim 11 may be inserted in a sandwich manner between the fiber layer (A) 12 constituting the first outer surface of the artificial leather and the fiber layer (B) 13 constituting the second outer surface of the artificial leather, thus forming a three-layer structure with the fibers tangled between the layers, this structure being preferred for dimensional stability, tensile strength and tear strength.
  • a three-layer structure of the fiber layer (A), fiber layer (B) and a scrim inserted between them also allows the fiber layer (A) and fiber layer (B) to have separate designs, and is therefore preferred from the viewpoint of free customization of the diameters and types of fibers composing each layer to match the functions and usages required for artificial leather.
  • using ultrafine fibers for fiber layer (A) and flame-retardant fibers for fiber layer (B) allows both excellent surface quality and high flame retardance to be obtained.
  • the fiber sheet when it includes a scrim, it may be a woven or knitted fabric scrim which is preferably made of a polymer of the same type as the fibers composing the fiber layer (A), from the viewpoint of obtaining the same color by dyeing.
  • the fibers of the fiber layer (A) are polyester-based, for example, the fibers of the scrim are also preferably polyester-based, and when the fibers of the fiber layer (A) are polyamide-based, the fibers of the scrim are also preferably polyamide-based.
  • a knitted fabric scrim it is preferably a single knit of 22-gauge to 28-gauge.
  • a woven fabric scrim can exhibit higher dimensional stability and strength than a knitted fabric.
  • the woven fabric texture may be a plain weave, twill weave or satin weave, but is preferably a plain weave from the viewpoint of cost and tangling properties.
  • the yarn composing the woven fabric may be monofilament or multifilament yarn.
  • the single fiber fineness of the yarn is preferably 5.5 dtex or smaller to more easily obtain flexible artificial leather.
  • the form of the yarn composing the woven fabric may be fully drawn yarn of polyester or polyamide, or false twisted yarn with added twisting of 0 to 3000 T/m.
  • multifilaments When multifilaments are used they may be common ones, and are preferably 33 dtex/6f, 55 dtex/24f, 83 dtex/36f, 83 dtex/72f, 110 dtex/36f, 110 dtex/48f, 167 dtex/36f or 166 dtex/48f polyester or polyamide, for example.
  • the yarn composing a woven fabric may consist of multifilament long fibers.
  • the woven density of the yarn in a woven fabric is preferably 30 to 150/inch and more preferably 40 to 100/inch from the viewpoint of obtaining artificial leather that is flexible with excellent mechanical strength.
  • the basis weight of the woven fabric is preferably 20 to 150 g/m 2 .
  • the presence or absence of false twisting, the number of twists, the multifilament single fiber fineness and woven density for a woven fabric also contribute to the tangling properties between the fibers composing the fiber layer (A) and the optional fiber layer (B), and to the mechanical properties including flexibility, seam strength, tearing strength, tensile strength and elongation and stretchability of the artificial leather, and they may be selected as appropriate for the desired physical properties and intended use.
  • the fiber layer (A) in the artificial leather of this embodiment is preferably composed of ultrafine fibers with mean diameters of 0.3 ⁇ m to 7 ⁇ m, more preferably 2 ⁇ m to 6 ⁇ m and even more preferably 2 ⁇ m to 5 ⁇ m. If the mean diameter of the fibers is 1 ⁇ m or greater, the abrasion resistance, dye coloring properties and light fastness will be satisfactory. If the mean diameter of the fibers is 8 ⁇ m or smaller, on the other hand, the large number density of the fibers will result in a high luxuriant feel and smooth surface tactile sensation, to obtain artificial leather with more satisfactory surface quality.
  • the fibers composing the fiber layers of the artificial leather may be synthetic fibers, which includes polyester-based fibers such as polyethylene terephthalate, polybutylene terephthalate and polytrimethylene terephthalate; and polyamide-based fibers such as nylon 6, nylon 66 and nylon 12.
  • polyester-based fibers such as polyethylene terephthalate, polybutylene terephthalate and polytrimethylene terephthalate
  • polyamide-based fibers such as nylon 6, nylon 66 and nylon 12.
  • polyethylene terephthalate is preferred among these from the viewpoint of excellent color fastness without yellowing of the fibers themselves when exposed to direct sunlight for long periods.
  • the fibers composing the fiber layer of the artificial leather are more preferably made of chemical-recycled or material-recycled polyethylene terephthalate, or polyethylene terephthalate obtained using a plant-derived starting material.
  • the basis weight of the fibers of the fiber layer (A) is preferably 40 g/m 2 to 500 g/m 2 , more preferably 50 g/m 2 to 370 g/m 2 and even more preferably 60 g/m 2 to 320 g/m 2 , from the viewpoint of mechanical strength including abrasion resistance.
  • the basis weight of the fibers of the fiber layer (A) is preferably 10 g/m 2 to 200 g/m 2 , more preferably 30 g/m 2 to 170 g/m 2 and even more preferably 60 g/m 2 to 170 g/m 2 , from the viewpoint of mechanical strength including abrasion resistance.
  • the basis weight of the fibers of the fiber layer (B) is preferably 10 g/m 2 to 200 g/m 2 and more preferably 20 g/m 2 to 170 g/m 2 , from the viewpoint of cost and facilitated production.
  • the basis weight of the scrim is preferably 20 g/m 2 to 150 g/m 2 , more preferably 20 g/m 2 to 130 g/m 2 and even more preferably 30 g/m 2 to 110 g/m 2 from the viewpoint of mechanical strength and tangling between the fiber layers and scrim.
  • the basis weight of the artificial leather filled with the PU resin is preferably 50 g/m 2 to 550 g/m 2 , more preferably 60 g/m 2 to 400 g/m 2 and even more preferably 70 g/m 2 to 350 g/m. 2
  • the method for producing each fiber layer forming the fiber sheet of the artificial leather may be a direct spinning method (such as a spunbond method or meltblown method), or a method of forming a fiber sheet with staple fibers (such as a carding method, airlaid method or other dry method, or a wet method such as a papermaking method), which are all suitable, but for this embodiment sea-island fibers (SIF) are used as the starting material.
  • a fiber sheet produced using staple fibers is preferred because it has low basis weight variation and excellent homogeneity, and tends to form uniform piles and thus improve the surface quality for artificial leather.
  • Fibers capable of ultrafine fiber generating may be used as the means for forming the ultrafine fibers of the fiber sheet. Using fibers capable of ultrafine fiber generating can stabilize the entangling forms of the ultrafine fiber bundles.
  • the fibers capable of ultrafine fiber generating used may be sea-island fibers having two thermoplastic resin components with different solvent solubilities as the sea component and island component, with the island component as the ultrafine fibers by dissolving removal of the sea component with a solvent, or peelable composite fibers having two thermoplastic resin components situated alternately in a radial or multilayer manner in the fiber cross-sections and being split into ultrafine fibers by peeled splitting of the components.
  • Sea-island fibers can provide suitable voids between the island component (ultrafine fibers) by removal of the sea component, and are therefore preferred for use from the viewpoint of flexibility and texture of the sheet.
  • Sea-island fibers include sea-island composite fibers obtained by spinning the sea component and island component in mutual alignment using a sea-island compositing nozzle, and sea-island mixed fibers obtained by spinning a mixture of the sea component and island component. Sea-island composite fibers are preferably used from the viewpoint of obtaining ultrafine fibers of uniform fineness and of obtaining ultrafine fibers of adequate length to contribute to the sheet strength.
  • the sea component for sea-island fibers may be a copolymerized polyester obtained by copolymerizing polyethylene, polypropylene, polystyrene, sodium sulfoisophthalic acid or polyethylene glycol, or polylactic acid.
  • a copolymerized polyester obtained by copolymerizing polyethylene, polypropylene, polystyrene, sodium sulfoisophthalic acid or polyethylene glycol, or polylactic acid.
  • an alkali-decomposable copolymerized polyester obtained by copolymerizing sodium sulfoisophthalic acid or polyethylene glycol, or polylactic acid, which can be decomposed without using organic solvents.
  • the sea component is preferably removed before the PU resin is applied to the fiber sheet. Removal of the sea component before application of the PU resin allows the ultrafine fibers to be firmly held since the structure has the PU resin directly adhering to the ultrafine fibers, and therefore results in satisfactory abrasion resistance of the sheet.
  • the method of tangling the fibers or fiber bundles of the fiber web may be by cutting the sea-island fibers to predetermined fiber lengths to form staple fibers, passing them through a carding machine and cross lapper to form a fiber web, and tangling them by hydroentangling treatment by means of needle punching or any desired spunlace method.
  • the number of needle barbs used is preferably 1 to 9. If the number of barbs is 1 or greater a tangling effect will be obtained and damage to the fibers can be minimized. If the number of barbs is 9 or less, damage to the fibers can be reduced in size and fewer needle marks will be left in the artificial leather, allowing the outer appearance of the product to be improved.
  • the total barb depth (length from the tip to the base of the barb) is preferably 0.05 mm to 0.10 mm. If the total barb depth is 0.05 mm or greater, the barbs will be able to satisfactorily hook the fibers, allowing efficient fiber tangling to be achieved. If the total barb depth is 0.10 mm or less, fewer needle marks will be left on the artificial leather, resulting in improved quality. Considering the balance between barb strength and fiber tangling, the total barb depth is more preferably 0.06 mm to 0.08 mm.
  • the punch density range is preferably 300/cm 2 to 6000/cm 2 and more preferably 1000/cm 2 to 6000/cm 2 .
  • the fiber sheet obtained by needle punching may be immersed for 2 minutes in 98°C water for shrinkage, and dried at a temperature of 100°C for 5 minutes to form the fiber sheet prior to sea removal.
  • Removal of the sea component may be carried out by immersing the sea-island fibers in a solvent to cause shrinkage.
  • the solvent used to dissolve the sea component may be an aqueous alkali solution of sodium hydroxide or the like when the sea component is a copolymerized polyester or polylactic acid.
  • the removal of the sea component is preferably carried out with an aqueous alkali solution of sodium hydroxide.
  • the staple fiber lengths are preferably 13 mm to 102 mm, more preferably 25 mm to 76 mm and even more preferably 38 mm to 76 mm for a dry method (carding method or airlaid method), and preferably 1 mm to 30 mm, more preferably 2 mm to 25 mm and even more preferably 3 mm to 20 mm for a wet method (papermaking method).
  • the aspect ratio (L/D) as the ratio of the length (L) and diameter (D), is preferably 500 to 2000 and more preferably 700 to 1500.
  • This aspect ratio range is preferred because the dispersibility and dispersibility of the staple fibers in the slurry of the staple fibers dispersed in water will be satisfactory during preparation of the slurry, the fiber layer strength will be satisfactory, and fiber balls known as "pilling" caused by abrasion will be less likely to be outwardly apparent since the fiber lengths are shorter than by a dry method, allowing the single filaments to more easily disperse.
  • the fiber lengths of staple fibers with diameters of 4 ⁇ m, for example, are preferably 2 mm to 8 mm and more preferably 3 mm to 6 mm.
  • the fiber sheet is impregnated with a water-dispersed PU resin dispersion, and then the PU resin is coagulated by heating to fill the sheet with the PU resin.
  • the PU resin is impregnated as an impregnating liquid in the form of a dispersion (water-dispersed form).
  • the concentration of the PU resin in the impregnating liquid may be 10 to 35 mass%, for example.
  • the impregnating liquid is prepared and impregnated into the fiber sheet so that the PU resin proportion is 15 to 50 mass% with respect to 100 mass% of the fiber sheet.
  • Water-dispersed PU resins are classified as forced-emulsifying PU resins that are forcibly dispersed and stabilized using a surfactant, and self-emulsifying PU resins that have a hydrophilic structure in the PU molecular structure and disperse and stabilize in water without the presence of a surfactant. Either type may be used for this embodiment.
  • the water-dispersed PU resin dispersion may be impregnated and coated onto the fiber sheet, and subjected to dry heat coagulation, moist heat coagulation, hot water coagulation or a combination of these, to coagulate the PU resin.
  • the temperature for moist heat coagulation is preferably 40 to 200°C, and above the heat-sensitive coagulation temperature of the PU resin. If the moist heat coagulation temperature is 40°C or higher and more preferably 80°C or higher, then it will be possible to shorten the time until coagulation of the PU resin and better inhibit its migration. If the moist heat coagulation temperature is 200°C or lower and more preferably 160°C or lower, heat degradation of the PU resin or PVA resin can be prevented.
  • the temperature for hot water coagulation is preferably 40 to 100°C, and above the heat-sensitive coagulation temperature of the PU resin. If the hot water coagulation temperature in hot water is 40°C or higher and more preferably 80°C or higher, then it will be possible to shorten the time until coagulation of the PU resin and better inhibit its migration.
  • the dry coagulation temperature and drying temperature are preferably 80 to 180°C. A dry coagulation temperature and drying temperature of 80°C or higher and more preferably 90°C or higher will result in excellent productivity. If the dry coagulation temperature and drying temperature are 180°C or lower and more preferably 160°C or lower, heat degradation of the PU resin or PVA resin can be prevented.
  • the means for removing the hot water-soluble resin from the sheet may be, for example, a method of immersion in hot water at 60°C or higher and preferably 80°C or higher, or a method of removing the hot water-soluble resin while circulating hot water at 80°C or higher in a jet dyeing machine before dyeing.
  • a method of removing the hot water-soluble resin in a jet dyeing machine is especially preferred because it can eliminate the steps of drying and winding of the sheet after removal of the hot water-soluble resin, and thus increase production efficiency.
  • removal of the hot water-soluble resin from the sheet after application of the PU resin yields a flexible sheet. While the method of removing the hot water-soluble resin is not particularly restricted, a preferred aspect is dissolving removal by immersion of the sheet in hot water at 60 to 100°C, with squeezing using a mangle if necessary.
  • the sheet filled with the PU resin may be sliced in half horizontally, if it does not include a scrim. This can increase production efficiency.
  • the PU resin-filled sheet may be coated with a lubricant, such as a silicone dispersion.
  • a lubricant such as a silicone dispersion.
  • Application of an antistatic agent before buffing treatment is also preferred so that grinding powder generated from the sheet by grinding will be less likely to accumulate on sandpaper.
  • Buffing treatment may be carried out to form naps on the surface of the sheet.
  • the buffing treatment may be by a method of grinding using sandpaper or a roll sander. Applying silicone as a lubricant before buffing treatment allows naps to be easily formed by surface grinding, resulting in very satisfactory surface quality.
  • the artificial leather is preferably subjected to dyeing treatment to increase the value for sensibility (i.e. the visual effect).
  • Dyestuff may be selected according to the type of fibers composing the fiber sheet, and for example, a disperse dyestuff may be employed for polyester-based fibers, an acid dyestuff or metal complexed dyestuff may be employed for polyamide-based fibers, or any combination of such dyestuffs may be used. When a disperse dyestuff has been used for dyeing, the dyeing may be followed by reduction cleaning.
  • the dyeing method used may be any one commonly known in the dyeing industry.
  • the dyeing method preferably employs a jet dyeing machine to simultaneously provide a rubbing effect while the sheet is dyed, in order to soften the sheet.
  • the dyeing temperature will depend on the type of fiber but is preferably 80 to 150°C. If the dyeing temperature is 80°C or higher and more preferably 110°C or higher it will be possible to efficiently dye the fibers. If the dyeing temperature is 150°C or lower and more preferably 130°C or lower it will be possible to prevent degradation of the PU resin.
  • the artificial leather dyed in this manner is preferably subjected to soaping and if necessary reduction cleaning (cleaning in the presence of a chemical reducing agent) to remove the excess dyestuff. It is also preferred to use a dyeing aid during dyeing. Using a dyeing aid can increase the dyeing uniformity and reproducibility. Whether in the same bath as dyeing or after dyeing, finishing-process may be carried out using a flexibilizer such as silicone, or an antistatic agent, water-repellent agent, flame retardant, light fastness agent or antimicrobial agent.
  • a flexibilizer such as silicone, or an antistatic agent, water-repellent agent, flame retardant, light fastness agent or antimicrobial agent.
  • the artificial leather of this embodiment can be suitably used as an interior finishing material with a very delicate outer appearance when used as an upholstery for furniture, chairs or wall materials, or for seats, ceilings or interior finishings for vehicle interiors of automobiles, electric railcars or aircraft, or as clothing materials used in parts of shirts, jackets, uppers or trims for shoes including casual shoes, sports shoes, men's shoes or women's shoes, or bags, belts and wallets, or even as industrial materials such as wiping cloths, abrasive cloths or CD curtains.
  • An artificial leather sample cut with scissors was packed into a 1 cm-diameter pulse NMR glass tube to a height of about 1.0 cm to 1.5 cm, and provided for measurement.
  • embossing After inserting a sample between an embossing roll with an embossing ratio of 40%, and a presser roll, which had raised section heights of 300 ⁇ m and were heated to 200°C, at a speed of 2.0 m/min, embossing was carried out with a linear pressure of 60 kg/cm to obtain a sample having a concave design.
  • the PU resin proportion with respect to the total mass of the sheet fibers was measured by the following method.
  • the mass of the fiber sheet before PU resin impregnation is recorded as A (g).
  • the fiber sheet is impregnated with the PU resin dispersion, and then a pin tenter dryer is used for heated air drying at 130°C, after which it is immersed in hot water heated to 90°C for softening and dried, to obtain a fiber sheet filled with the PU resin (hereunder also referred to as "resin-filled fiber sheet”).
  • the mass of the resin-filled fiber sheet (sheet) is designated as B1 (g).
  • the mean diameter of fibers composing the fiber sheet is determined by photographing the first outer surface of the artificial leather using a scanning electron microscope (SEM, "JSM-5610" by JEOL Corp.), at a magnification of 1500x, randomly selecting 100 fibers on the first outer surface of the artificial leather, measuring the diameters of the single filament cross-sections, and determining the arithmetic mean value for the 100 fibers.
  • SEM scanning electron microscope
  • the distance between the outer circumferences on a straight line perpendicular to the middle point of the longest diameter of the single fiber cross section was taken as the fiber diameter.
  • Fig. 2 is a conceptual drawing illustrating how a fiber diameter is determined.
  • the fiber diameter is considered to be the outer circumferential distance c on a straight line b perpendicular to the midpoint p of the maximum diameter "a" of the cross-section A in the observed image.
  • Measurement was performed using a laser diffraction particle size distribution analyzer ("LA-920" by Horiba, Ltd.) according to the manufacturer's instruction manual, and the median diameter was recorded as the mean primary particle size.
  • resin A aqueous urethane resin composition (hereunder referred to as "resin A”) (nonvolatile content: 40 mass%, mean primary particle size: 0.34 ⁇ m).
  • resin B aqueous urethane resin composition (hereunder referred to as "resin B”) (nonvolatile content: 40 mass%, mean primary particle size: 0.53 ⁇ m).
  • resin C aqueous urethane resin composition (hereunder referred to as "resin C”) (nonvolatile content: 40 mass%, mean primary particle size: 0.19 ⁇ m).
  • resin E aqueous urethane resin composition
  • resin F aqueous urethane resin composition (hereunder referred to as "resin F”) (nonvolatile content: 40 mass%, mean primary particle size: 0.52 ⁇ m).
  • resin G aqueous urethane resin composition (hereunder referred to as "resin G”) (nonvolatile content: 40 mass%, mean primary particle size: 0.40 ⁇ m).
  • resin H aqueous urethane resin composition (hereunder referred to as "resin H”) (nonvolatile content: 40 mass%, mean primary particle size: 0.38 ⁇ m).
  • aqueous urethane resin composition hereunder referred to as "resin I" (nonvolatile content: 40 mass%, mean primary particle size: 0.20 ⁇ m).
  • sea-island composite fiber with a mean fiber fineness of 18 ⁇ m was obtained with a composite ratio of 20 mass% sea component and 80 mass% island component, and 16 islands/1f.
  • the obtained sea-island composite fiber was cut to fiber lengths of 51 mm as staple fibers and passed through a carding machine and cross lapper to form a fiber web, and after layering the obtained fiber web, it was needled-punched to obtain a fiber sheet.
  • the obtained fiber sheet was immersed in 95°C hot water for contraction and a pin tenter dryer was used for drying at 100°C for 5 minutes, to obtain a single-layer fiber sheet with a basis weight of 600 g/m 2 .
  • the obtained fiber sheet was immersed in a 10 g/L sodium hydroxide aqueous solution that had been heated to 95°C for 25 minutes of treatment, for removal of the sea component of the sea-island composite fibers.
  • the single fiber mean diameter of the fibers composing the fiber sheet after sea component removal was 4 ⁇ m.
  • PVA with a saponification degree of 98 to 99% and a polymerization degree of 1200 was added to water at a temperature of 25°C, and the mixture was heated to a temperature of 90°C, keeping the temperature at 90°C while stirring for 2 hours, to prepare an aqueous solution with a 10 mass% solid content as a PVA aqueous solution.
  • the fiber sheet from which the sea component had been removed was impregnated with the PVA aqueous solution and heat dried for 10 minutes at a temperature of 140°C, to obtain a PVA-added sheet having a PVA adhesion amount of 15 mass% with respect to the fiber mass of the fiber sheet.
  • a half-cut machine with an endless band knife was then used for half-cutting of the sheet perpendicular to the thickness direction, and the non-half-cut side was subjected to buffing treatment using #400 emery paper, after which a jet dyeing machine was used for dyeing at 130°C for 15 minutes with a blue disperse dyestuff ("BlueFBL" by Sumitomo Chemical Co., Ltd.) at a 5.0% owf dyeing density, and reduction cleaning was carried out.
  • a hot air drier was then used for drying at 100°C for 5 minutes to obtain single-layer artificial leather.
  • the staple fibers of Example 1 were processed with a carding machine and cross lapper to produce a fiber web with a basis weight of 128 g/m 2 , which was used as fiber layer (A).
  • a fiber web with a basis weight of 60 g/m 2 was also produced by the same method for use as fiber layer (B).
  • a scrim plain weave fabric with a basis weight of 95 g/m 2 composed of 166 dtex/48f polyethylene terephthalate fibers was inserted between fiber layer (A) and fiber layer (B), forming a 3-layer body, which was then processed by needle punching to form a fiber sheet having a three-layer structure.
  • the sheet was immersed in a bath at a temperature of 97°C for shrinkage and dried using a pin tenter dryer at 100°C for 5 minutes, after which it was immersed for 25 minutes in a 10 g/L-concentration aqueous sodium hydroxide solution which had been heated to a temperature of 95°C, and then treated for removal of the sea component of the sea-island composite fibers.
  • the single fiber mean diameter of the fibers composing the fiber sheet after sea component removal was 4 ⁇ m.
  • PVA with a saponification degree of 98 to 99% and a polymerization degree of 1200 was added to water at a temperature of 25°C, and the mixture was heated to a temperature of 90°C, keeping the temperature at 90°C while stirring for 2 hours, to prepare an aqueous solution with a 10 mass% solid content as a PVA aqueous solution.
  • the fiber sheet from which the sea component had been removed was impregnated with the PVA aqueous solution and heat dried for 10 minutes at a temperature of 140°C, to obtain a PVA-added sheet having a PVA adhesion amount of 15 mass% with respect to the fiber mass of the fiber sheet.
  • An impregnating liquid containing the water-dispersed polyurethane resin E obtained in Synthesis Example 5 at 25.0% (solid mass%) in the impregnating liquid and anhydrous sodium sulfate as an impregnation aid at 3.0 wt% (solid mass%) in the impregnating liquid was then used for impregnation into the PVA-added sheet, after which moist heat coagulation was carried out for 5 minutes at 100°C and a hot air drier was used for hot air drying at 130°C for 5 minutes.
  • the outer surface of the fiber layer (A) of the sheet was subjected to buffing treatment using #400 emery paper, after which a jet dyeing machine was used for 15 minutes of dyeing at 130°C with a blue disperse dyestuff ("BlueFBL" by Sumitomo Chemical Co., Ltd.) to a dyeing density of 5.0% owf, and reduction cleaning was carried out.
  • a hot air drier was then used for drying at 100°C for 5 minutes to obtain artificial leather with a three-layer structure.
  • Example 1 Resin D 3.5 650 20 2 11% 12% Comp.
  • Example 2 Resin D 3.5 650 60 2 34% 51% Comp.
  • Example 3 Resin F 7.5 850 20 2 11% 12% Comp.
  • Example 4 Resin G 0 412 20 2 11% 12% Comp.
  • Example 5 Resin H 1 450 43 2 23% 30% Comp.
  • Example 6 Resin I 1 925 42 2 33% 30% Comp.
  • Example 7 Resin H 1 452 59 1 32% 47% Comp.
  • Example 8 Resin I 1 920 61 1 33% 50%
  • the embossing clarity was more satisfactory in Examples 1 to 11, where the L component spin-spin relaxation time Tl was 500 ⁇ sec to 800 ⁇ sec and the L component fraction Cl was 25% or greater and less than 55% with fitting of the free induction decay (FID) signal in pulse NMR (solid echo method, proton observation, measuring temperature: 50°C) to two components: the S component (Gaussian component) and L component (Lorentz component), compared to Comparative Examples 1 to 8 in which the values were outside of these ranges.
  • FID free induction decay
  • the artificial leather of the invention has a low environmental impact while also having excellent embossing clarity, and it can therefore be suitably used for upholstery or interior materials for seats in interiors, automobiles, aircraft and railway vehicles, or for clothing products. More specifically, the artificial leather of the invention can be suitably used as an interior finishing material with a very delicate outer appearance when used as an upholstery for furniture, chairs or wall materials, or for seats, ceilings or interior finishings for vehicle interiors of automobiles, electric railcars or aircraft, or as clothing materials used in parts of shirts, jackets, uppers or trims for shoes including casual shoes, sports shoes, men's shoes or women's shoes, or bags, belts and wallets, or even as industrial materials such as wiping cloths, abrasive cloths or CD curtains.

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  • Engineering & Computer Science (AREA)
  • Textile Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Dispersion Chemistry (AREA)
  • Synthetic Leather, Interior Materials Or Flexible Sheet Materials (AREA)
  • Macromonomer-Based Addition Polymer (AREA)
EP23190797.3A 2022-08-12 2023-08-10 Kunstleder Pending EP4324979A2 (de)

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4506754B2 (ja) 2004-03-30 2010-07-21 東レ株式会社 シート状物及び内装材
JP6582992B2 (ja) 2014-10-24 2019-10-02 東レ株式会社 シート状物

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4506754B2 (ja) 2004-03-30 2010-07-21 東レ株式会社 シート状物及び内装材
JP6582992B2 (ja) 2014-10-24 2019-10-02 東レ株式会社 シート状物

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