JP2008106415A - Sheet body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a napped leather like sheet body having graceful appearance caused by napping, excellent in durability such as hydrolyzability, durability. <P>SOLUTION: The sheet body includes a nonwoven fabric composed of entangled superfine fibers with a single fiber fineness of less than 0.5 dtex, and an elastic resin binder principally containing polyurethane existing in an inner space of the nonwoven fabric, wherein the polyurethane has a carbonate structure represented by specific chemical formulas (1) and (2). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a sheet-like material, particularly a napped-toned leather-like sheet material.

  It is widely used to obtain suede or nubuck-like napped leather-like sheet-like materials by grinding the surface of a sheet-like material impregnated with polyurethane resin on a fiber substrate using sandpaper and raising the fibers. Are known. The characteristics of the target leather-like sheet can be arbitrarily designed in a wide range by combining the substrate made of fibers and the polyurethane resin. As these polyurethane resins, for example, polyurethane resins using polytetramethylene glycol, organic diisocyanate, and glycol chain extenders have been proposed (see, for example, Patent Document 1). According to Patent Document 1, it is described that by using the polyurethane resin, it is possible to obtain an artificial leather-like material having an extremely flexible texture that is not inferior to a high-grade wool fabric used for a suit or the like. ing.

  Napped-toned leather-like sheets have an appearance and surface very similar to natural leather, and have advantages such as uniformity and dyeing fastness that are not found in natural leather. In addition, it has been spreading to applications that are used over a long period of time, such as 5 to 10 years, such as car seat skins.

  For this reason, in the polyether-based polyurethane resin using polytetramethylene glycol as described in Patent Document 1, it is easily deteriorated by ultraviolet rays or heat. There was a problem that it could not withstand long-term use. Polyester-based polyurethane resin is also a polyurethane resin often used for leather-like sheets, but although it has good light resistance due to ultraviolet rays etc., the ester bond deteriorates due to hydrolysis. There were similar problems such as the occurrence of peaches and hairballs.

  On the other hand, polycarbonate polyurethane resins obtained by reacting polycarbonate polyols, alicyclic polyisocyanates and aromatic polyisocyanates are also useful polyurethane resins for applications with high durability such as furniture and vehicle seats. It has been proposed (see, for example, Patent Document 2). Here, a polyurethane using polyhexamethylene carbonate is disclosed as a polycarbonate-based polyurethane resin. However, when this polyurethane is used as an impregnation resin on a nonwoven fabric in which ultrafine fibers are entangled, the texture of the sheet-like material When the surface fibers are raised with sandpaper or the like, the surface of the polyurethane is too hard, resulting in a rough surface with a short rough surface, which is good with an elegant raised surface. It was extremely difficult to obtain a high quality.

  A polycarbonate / polycarbonate / polyester diol combined with 30 to 90% by weight of polycarbonate diol, mainly polyhexamethylene carbonate diol, for the purpose of achieving both napped quality and durability such as light resistance and hydrolysis resistance. Napped leather-like sheet-like materials using polyether-based polyurethane resins and polycarbonate / polyester-based polyurethane resins have been proposed (for example, see Patent Document 3). However, when the ratio of the polycarbonate diol is 70% by weight or less, durability is insufficient due to deterioration of the polyether component or the polyester component, while when the ratio of the polycarbonate diol is 70% by weight or more, Polyurethane became too hard, and when the surface was ground with sandpaper or the like, the surface napping was short and rough, and it was difficult to obtain napped leather-like sheet-like material satisfying both napping quality and durability. .

  In addition, in a leather-like sheet in which a resin layer is applied or laminated on a fibrous base material, so-called synthetic leather, it is known to use a polycarbonate-based polyurethane resin for the resin layer for the purpose of improving durability. Various proposals have been made for polycarbonate-based polyurethane resins used in this resin layer mainly for the purpose of improving the texture of synthetic leather.

  For example, a polyurethane resin using a copolymerized polycarbonate diol derived from 1,6-hexanediol and 1,5-pentanediol, or a copolymerized polycarbonate derived from 1,6-hexanediol and 1,4-butanediol Polyurethane resin using diol (for example, refer to Patent Document 4), polyurethane resin using polycarbonate diol derived from 2-methyl-1,8-octanediol (for example, refer to Patent Document 5), carbon number 5-6 A polyester / polycarbonate polyurethane resin using a polyester diol derived from alkanediol and dicambonic acid and a polycarbonate diol derived from an alkanediol having 8 to 10 carbon atoms (see, for example, Patent Document 6), 8 to 10 carbon atoms The Arcandio Polycarbonate / polyether-based polyurethane resin in combination with polycarbonate diols and polyether diols derived from have been proposed (e.g., see Patent Document 7).

  As a resin impregnated into these nonwoven fabrics in which ultrafine fibers are entangled with each other, sheet-like materials existing in the interior space of the nonwoven fabrics, in particular, the napped texture in which the surface fibers are raised by grinding the surface with sandpaper etc. When applied to a leather-like sheet, for example, in the copolymerized polyurethane resin having 4 to 6 carbon atoms described in Patent Document 4, a softening effect that can be ground by sandpaper cannot be obtained. In addition, since the surface napping becomes a short and rough surface, it is extremely difficult to obtain a good quality having elegant napping. In addition, since the polycarbonate-based polyurethane resin derived from 2-methyl-1,8-octanediol described in Patent Document 5 uses a long-chain alkylene diol, it is impregnated into a nonwoven fabric and then wet coagulated. Is extremely fast, and foaming of polyurethane inside the nonwoven fabric becomes large and rough, and as a result of partial foaming failure, there is unevenness in the length of surface napping when grinding with sandpaper. There was a problem that only a poor one could be obtained. Further, when the surface of the obtained sheet-like material is rubbed with a brush or the like, there is a problem in abrasion resistance because many fibers fall off. The polyurethane resins described in Patent Documents 6 and 7 are durable in the long-term use of napped leather-like sheet-like materials from the viewpoint of hydrolysis resistance or light resistance in that polyester diol and polyether diol are used in combination. It does not lead to improvement of the property, particularly the problem of surface fiber peaches and pills.

  Furthermore, the techniques described in Patent Documents 4 to 7 are mainly aimed at improving the surface properties such as texture, surface smoothness, stickiness and cracking of the polyurethane resin layer provided on the base material. Improved sandability with sandpaper when polyurethane resin is present in the inner space of the nonwoven fabric, preferred napped length of fine fibers, resulting in a graceful appearance and supple surface touch, soft texture Nothing was taken into account.

  On the other hand, for items that are in direct contact with the human body, such as interior products and car seat products, and those that are used in contact with the human body must also be considered for deterioration due to sweat and oil secreted from the head, back, arms, etc. Conventionally, the resistance to sweat deterioration has been evaluated using an artificial sweat solution defined in JIS L0848 (2005 edition). However, although there is little deterioration in this evaluation method, there have been some reports of deterioration that seems to be apparently due to sweat in actual use, and it has high durability even under conditions more reflecting actual use conditions. Development of sheet-like materials has been required. For this reason, for example, a polyurethane obtained by copolymerizing a polymer diol mainly composed of polycarbonate and a polymer diol mainly composed of polyethylene glycol as a polyurethane having high oleic acid resistance in addition to light resistance and hydrolysis resistance has been proposed. (For example, refer to Patent Document 8). However, when this polyurethane is used as an impregnating resin for a nonwoven fabric in which ultrafine fibers are entangled, a polymer diol mainly composed of polyethylene glycol is used, so that there is a problem that the light resistance is inferior. . In addition, the evaluation using oleic acid alone has a problem that it cannot be sufficiently correlated with deterioration during actual use.

Furthermore, for the purpose of providing a porous sheet material that is uniform and microporous and rich in flexibility, it is composed of a polycarbonate diol composed of an alkanediol having 4 to 6 carbon atoms and an alkanediol having 7 to 12 carbon atoms. A polyurethane resin for synthetic leather obtained by reacting a polycarbonate diol, an organic diisocyanate, and a chain extender has been proposed (see, for example, Patent Document 9). However, when both of the two types of polycarbonate diol have side chains, or when only one of the polycarbonate diols has a side chain, if the carbon concentration having a branch in the polycarbonate diol molecule is too high, hydrolysis resistance, There is a problem that the durability such as light resistance is inferior, the texture of the sheet is excessively soft, and the physical properties of the sheet-like material are inferior.
Japanese Patent Laid-Open No. 59-19279 JP-A-3-244619 JP 2002-30579 A JP-A-5-5280 JP-A-2-33384 Japanese Patent Laid-Open No. 4-300368 JP-A-5-9875 JP-A-5-25781 JP 2005-171226 A

  In view of the background of the above-mentioned conventional technology, the present invention is excellent in sensibility such as flexibility and texture, and is excellent in light resistance, hydrolysis resistance, sweat resistance, and fiber dropout even in long-term use. It is intended to provide a sheet-like material with less generation of peaches and pills.

In order to solve the above problems, the present invention employs the following means. That is,
(1) In a sheet-like material comprising a non-woven fabric formed by entanglement of ultrafine fibers having a single fiber fineness of 0.5 dtex or less and an elastic resin binder mainly composed of polyurethane present in the internal space, the polyurethane is represented by the following general formula: A sheet-like material having a carbonate structure represented by (1) and (2).

(In the formula, R ₁ and R ₂ are straight-chain aliphatic hydrocarbon groups having 8 to 10 carbon atoms, and may be the same or different. X and y are positive integers, and R ₁ and R 2 _{If 2} is different, block copolymerization or random copolymerization)

(Wherein R ₃ and R ₄ are aliphatic hydrocarbon groups having 4 to 6 carbon atoms, which may be the same or different. W and z are positive integers, and R ₃ and R ₄ are When they are different, they are block copolymerization or random copolymerization, and at least one of R ₃ and R ₄ is an aliphatic hydrocarbon group having a methyl group branched)
(2) The ratio of the aliphatic hydrocarbon group in which the methyl group is branched is from 10% to 50% with respect to the total number of moles of R ₁ , R ₂ , R ₃ and R ₄ contained in the polyurethane. The sheet-like material as described in (1) above, which is characterized.

  (3) The sheet-like material as described in any one of (1) to (2) above, wherein the polyurethane has a gelation point of from 2.5 ml to 6 ml.

(4) After subjecting the sheet-like material to a forced deterioration treatment under the following condition A, the Martindale abrasion test (10,000 friction) specified in JIS L1096 (2005 edition) was performed, and before and after the abrasion test. Martindale wear specified in JIS L1096 (2005 version) after appearance change is 3 or more according to the criteria specified in JIS L1076 (2005 version) and after forced degradation treatment under the following condition B (1) to (1), wherein the test (10,000 friction) is performed, and the change in appearance before and after the wear test is No. 3 or more according to the criteria defined in JIS L1076 (2005 edition). 3) The sheet-like material in any one of.
[Forced deterioration treatment condition A]: After applying artificial sebum having the following composition to 8% by weight based on the sheet weight, it was irradiated with light for 144 hours using a xenon arc lamp type light resistance tester stipulated in JIS L0843 B-6 (2005 edition).
[Forced deterioration treatment condition B]: 8% by weight of artificial sebum having the following composition was applied to the sheet weight, and then left in an atmosphere of 70 ° C. and 90% relative humidity for 5 weeks. Artificial sebum composition: stearic acid (15 parts by weight)
Oleic acid (15 parts by weight)
Beef tallow extremely hardened oil (15 parts by weight)
Olive oil (15 parts by weight)
Cetyl alcohol (15 parts by weight)
Paraffin (15 parts by weight)
Cholesterol (5 parts by weight)
(5) The sheet-like material according to any one of (1) to (4), wherein the ultrafine fiber is made of polyester.

  (6) The non-woven fabric is formed by entanglement of a fiber bundle of ultrafine fibers, and the elastic resin binder is substantially not present inside the fiber bundle of ultrafine fibers. The sheet-like material according to any one of (1) to (5).

  (7) The elastic resin binder is bonded to at least a part of a single fiber located on the outermost periphery of the fiber bundle of the ultrafine fibers, according to any one of (1) to (6), Sheet-like material.

  (8) The sheet-like product according to any one of (1) to (7), wherein the fineness CV of the single fiber in the fiber bundle of the ultrafine fiber is 10% or less.

  (9) The sheet-like material according to any one of (1) to (8), wherein the ultrafine fibers are raised on at least one surface of the sheet-like material.

  According to the present invention, it has an elegant appearance by napping and an appropriate softness and texture like natural leather, and is excellent in hydrolysis resistance, light resistance and sweat resistance, and even when used for a long period of time. It is possible to provide a sheet-like material with less generation of peach and pills.

  The present invention, as a result of earnestly examining a sheet-like material having an elegant appearance and moderate flexibility and texture like natural leather, and excellent in durability such as hydrolysis resistance, light resistance, sweat resistance, Based on the evaluation using the forced deterioration condition, it was found that the sheet deterioration can be dealt with at the time of actual use, and it was investigated to solve the above problems at once by using polyurethane having a specific composition.

  The sheet-like material of the present invention comprises a nonwoven fabric formed by entanglement of ultrafine fibers having a single fiber fineness of 0.5 dtex or less and an elastic resin binder mainly composed of polyurethane.

  As the material for the ultrafine fibers constituting the nonwoven fabric, a thermoplastic resin capable of melt spinning such as polyesters such as polyethylene terephthalate, polybutylene terephthalate and polytrimethylene terephthalate, polyamides such as 6-nylon and 66-nylon can be used. . Of these, polyester is preferably used from the viewpoint of strength, dimensional stability, and light resistance. Moreover, the ultra-fine fiber of a different material may be mixed with the nonwoven fabric.

  The single fiber fineness of the ultrafine fibers constituting the nonwoven fabric is preferably 0.001 dtex or more and 0.5 dtex or less from the viewpoint of sheet flexibility and napped quality. More preferably, it is 0.3 dtex or less, More preferably, it is 0.2 dtex or less. On the other hand, it is preferably 0.005 dtex or more, more preferably 0.01 dtex or more, from the viewpoints of color developability after dyeing, dispersibility of bundled fibers during napping treatment by buffing, and ease of spreading.

  The single fiber fineness referred to in the present invention is determined by the following method. That is, the section obtained by cutting the obtained sheet-like material in the thickness direction is observed with a scanning electron microscope (SEM) as an observation surface, and the fiber diameters of arbitrary 100 ultrafine fibers are measured to calculate the average value. It is obtained by conversion from the specific gravity of the thermoplastic resin used for the ultrafine fiber. When the ultrafine fiber has an irregular cross section, the cross-sectional area of the single fiber is measured, the diameter of a circle having an area equivalent to the area is calculated, and this is used as the fiber diameter of the ultrafine fiber. The single fiber fineness can be determined from the fiber diameter obtained here and the specific gravity of the thermoplastic resin used for the ultrafine fiber.

  As a means for obtaining ultrafine fibers, it is preferable to use ultrafine fiber generating fibers. By entanglement of the ultrafine fiber generating fiber in advance and then subdividing the fiber, a nonwoven fabric in which the ultrafine fibers are entangled in bundles can be obtained, and the ultrafine fibers are entangled in bundles Thus, the strength of the sheet can be obtained.

  As ultra-fine fiber generation type fibers, two-component thermoplastic resins with different solvent solubility are used as sea components and island components, and the sea components are dissolved and removed using a solvent, etc., so that the island components are made into ultra-fine fibers. It is possible to employ a peelable composite fiber that splits fibers into ultrafine fibers by alternately arranging fibers or two-component thermoplastic resin radially or in a multilayer shape on the fiber cross section, and separating and separating each component. Among them, the sea-island type composite fiber can provide an appropriate gap between the island components, that is, between the ultrafine fibers inside the fiber bundle by removing the sea component, so from the viewpoint of sheet flexibility and texture. Is also preferable.

  For the sea-island type composite fiber, a polymer inter-array system that uses the sea-island type composite base to spin the two components of the sea and the islands, and the mixed spinning method that mixes and spins the two components of the sea and the islands. However, a sea-island type composite fiber based on a polymer mutual array system is more preferable in that an ultrafine fiber having a uniform fineness can be obtained.

In particular, regarding the uniformity of the fineness, the fineness CV in the fiber bundle is preferably 10% or less.
The fineness CV referred to in the present invention is a value obtained by dividing the single fiber fineness standard deviation of the fibers constituting the fiber bundle by the average fineness within the bundle and expressed as a percentage (%), and is obtained by the following method. That is, a cross-section cut in the thickness direction of a sheet-like material is observed with a scanning electron microscope (SEM) as an observation surface, the fiber diameter of the ultrafine fibers constituting one bundle of bundled fibers is measured, and each ultrafine fiber is measured. The fineness of each single fiber is calculated from the fiber diameter and the specific gravity of the fiber component. The same measurement is performed on five bundle fibers, and the average value and the standard deviation value of the single fiber fineness are calculated from these. The average value is defined as the average fineness, and the value obtained by dividing the standard deviation value by the average value in percentage (%) is defined as the fineness CV. In addition, it is preferable that the fineness CV is 10% or less in the present invention, as the fineness CV value is smaller. Moreover, although a lower limit is not specifically limited, Usually, it will be 0.1% or more. By setting the fineness CV to 10% or less, the appearance of napping on the surface of the sheet can be elegant, and the dyeing can be uniform and good.

  As the sea component of the sea-island composite fiber, polyethylene, polypropylene, polystyrene, copolymerized polyester obtained by copolymerizing sodium sulfoisophthalic acid, polyethylene glycol, or the like, polylactic acid, or the like can be used.

  As the solvent for dissolving the sea component, an organic solvent such as toluene or trichloroethylene in the case of polyethylene, polypropylene, or polystyrene, and an alkaline aqueous solution such as sodium hydroxide can be used in the case of the copolymerized polyester or polylactic acid. It can be removed by immersing the sea-island composite fiber in it and applying a stenosis solution.

  In addition, the cross-sectional shape of the ultrafine fiber may be a round cross section, but may be a polygonal shape such as an ellipse, a flat shape, or a triangle, or an irregular cross section such as a sector shape or a cross shape.

  The nonwoven fabric constituting the sheet-like material of the present invention may be either a short fiber nonwoven fabric or a long fiber nonwoven fabric, but a short fiber nonwoven fabric is preferred when emphasis is placed on texture and quality. In addition, a woven fabric or a knitted fabric may be inserted into the nonwoven fabric for the purpose of improving the strength.

  As a method of entangled fibers to obtain a nonwoven fabric, a method of entanglement with a needle punch or a water jet punch can be employed.

  In the present invention, it is important that the polyurethane used as the main component of the elastic resin binder has a carbonate structure represented by the following general formulas (1) and (2).

(In the formula, R ₁ and R ₂ are straight-chain aliphatic hydrocarbon groups having 8 to 10 carbon atoms, and may be the same or different. X and y are positive integers, and R ₁ and R 2 _{If 2} is different, block copolymerization or random copolymerization)

(Wherein R ₃ and R ₄ are aliphatic hydrocarbon groups having 4 to 6 carbon atoms, which may be the same or different. W and z are positive integers, and R ₃ and R ₄ are When they are different, they are block copolymerization or random copolymerization, and at least one of R ₃ and R ₄ is an aliphatic hydrocarbon group having a methyl group branched)
By having these structures at the same time, the crystallinity of polyurethane is moderately inhibited, and a sheet-like material having hardness and strength suitable for grinding on the sheet with sandpaper or the like can be obtained. .

R ₁ and R ₂ shown in the general formula (1) and R ₃ and R ₄ shown in the general formula (2) may be the same or different, but the appropriate texture and physical properties of the sheet-like material In order to maintain, it is preferable that they are different from each other. Further, either one of R ₃ and R ₄ is an aliphatic hydrocarbon group branched from a methyl group, and the other is a linear aliphatic hydrocarbon It is preferable.

In the present invention, the molar number of the aliphatic hydrocarbon group in which the methyl group is branched with respect to the total number of moles of R ₁ , R ₂ , R ₃ and R ₄ contained in the general formulas (1) and (2). The number ratio is preferably 10% or more and 50% or less. When the molar ratio of the aliphatic hydrocarbon group having a branched methyl group is less than 10%, the texture of the sheet-like material tends to become hard. When the surface fibers are raised with sandpaper or the like, the polyurethane is hard. If the surface is too large, the napped surface is in a direction that results in a short and rough surface. On the contrary, when the molar ratio of the aliphatic hydrocarbon group having a branched methyl group exceeds 50%, the polyurethane becomes excessively flexible, and if the surface of the obtained sheet is rubbed with a brush or the like, the fibers fall off. This is not preferable because the wear resistance deteriorates and the durability such as hydrolysis resistance and light resistance deteriorates.

  In addition, the ratio of the number of moles of the aliphatic hydrocarbon having a branched methyl group contained in the polyurethane is obtained by immersing the sheet-like material in an organic solvent such as N, N-dimethylformamide and extracting the polyurethane from the sheet-like material, The extracted polyurethane is calculated by conducting NMR measurement and comparing the peak of the linear methylene structure with the peak of the branched methyl group structure. The molecular structure analysis of polyurethane can be determined by decomposing polyurethane in an organic solvent such as N, N-dimethylformamide heated as necessary, and analyzing the decomposition product by NMR or the like.

  More specifically, the polyurethane has a polycarbonate diol (A) having a hydroxyl group at both ends of a molecular chain having a carbonate skeleton represented by the general formula (1) and a carbonate skeleton represented by the general formula (2). It is preferable to have a structure obtained by a reaction between a polycarbonate diol (B) having a hydroxyl group at both ends of the molecular chain, an organic diisocyanate, and a chain extender.

  The carbonate skeleton as used in the present invention forms a polymer chain linked through a carbonate bond, and the polycarbonate diol has one hydroxyl group at both ends of the polymer chain. .

  The polycarbonate diol can be produced by a transesterification reaction between an alkylene glycol and a carbonate ester or a reaction between phosgene or chloroformate ester and an alkylene glycol.

  Examples of the alkylene glycol for obtaining a polycarbonate diol having a polycarbonate skeleton having a linear aliphatic hydrocarbon group having 8 to 10 carbon atoms represented by the general formula (1) include 1,8-octanediol and 1,9-nonane. Diol, 1,10-decanediol. These may be used alone, but it is preferable to copolymerize the two types as described above. Particularly preferred is a combination of 1,8-octanediol / 1,9-nonanediol or a combination of 1,9-nonanediol / 1,10-decanediol. When 1,8-octanediol and 1,10-decanediol are combined, the crystallinity of polyurethane becomes high, and when a sheet-like material is ground to obtain a napped leather-like sheet-like material, the napped surface is short and rough. This is not preferable.

  Examples of the alkylene glycol for obtaining a polycarbonate diol having a polycarbonate skeleton having a hydrocarbon group having 4 to 6 carbon atoms represented by the general formula (2) include 1,4-butanediol, 1,5-pentanediol, 1, Linear alkylene glycols such as 6-hexanediol, branched alkylene glycols such as 2-methyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, and the like can be used. Particularly preferably, a copolymer polycarbonate diol obtained from a linear alkylene glycol obtained from 1,6-hexanediol and 3-methyl-1,5-pentanediol and a branched alkylene glycol is a napped leather-like sheet. It is preferable because good napping quality tends to be obtained from the flexibility and the ease of grinding with sandpaper. Examples of the carbonic acid ester used for the transesterification include diethyl carbonate and diphenyl carbonate.

  From the viewpoint of improving durability such as hydrolysis resistance and light resistance, it is preferable to use only a polycarbonate diol as the polymer diol used in the synthesis of the polyurethane. Polymer diols other than polycarbonate diol, such as polyester diol, polylactone diol, It is preferable not to use castor oil-based polyol, polyether diol, polyester ether diol or the like.

  The number average molecular weight (Mn) of the polycarbonate diol is preferably 500 to 3,000, more preferably 1,500 to 2,500. By setting the number average molecular weight to 500 or more, the texture is prevented from becoming hard, and by setting the number average molecular weight to 3,000 or less, the strength as polyurethane can be maintained.

  Examples of organic diisocyanates used in the synthesis of polyurethane include aromatic diisocyanates such as 4,4′-diphenylmethane diisocyanate, paraphenylene diisocyanate, 1,5-naphthalene diisocyanate, paraxylene diisocyanate, metaxylene diisocyanate, and 4,4′-dicyclohexyl. Mention may be made of alicyclic diisocyanates such as methane diisocyanate and isophorone diisocyanate and aliphatic diisocyanates such as 1,6-hexamethylene diisocyanate. Of these, aromatic diisocyanates, particularly 4,4′-diphenylmethane diisocyanate, are preferably used from the viewpoint of durability such as strength and heat resistance of the resulting polyurethane.

  The ratio between the polycarbonate diol and the organic diisocyanate is preferably such that the molar ratio between the two is 1: 2 to 1: 5. Also, within this range, adjust the ratio of organic diisocyanate by lowering the ratio of organic diisocyanate when emphasizing the flexibility of the resulting polyurethane, and increasing the ratio of organic diisocyanate when emphasizing strength, heat resistance, and durability. Is possible.

  As the chain extender used for the synthesis of polyurethane, a compound having two or more active hydrogens can be used, and glycols such as organic diols and organic triols, amines such as organic diamines and triamines, hydrazine derivatives and the like are used. Can do.

  Examples of the organic diol include ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, methylpentanediol, 1,6-hexanediol, 1,7-heptanediol, 1 , 8-octanediol, 1,9-nonanediol, aliphatic diols such as 1,10-decanediol, alicyclic diols such as 1,4-cyclohexanediol and hydrogenated xylylene glycol, and aromatics such as xylene glycol Diols can be mentioned.

  Examples of organic diamines include ethylene diamine, isophorone diamine, xylene diamine, phenyl diamine, and 4,4'-diaminodiphenyl methane.

  Examples of hydrazine derivatives include hydrazine, adipic acid dihydrazide, isophthalic acid hydrazide, and the like.

  When importance is attached to the hydrolysis resistance of polyurethane, it is preferable to use an organic diol. Above all, in view of the strength, heat resistance and yellowing resistance of polyurethane, an aliphatic diol having 2 to 6 carbon atoms in the alkyl chain, particularly ethylene. Glycol is preferred.

  In the case where importance is attached to the heat resistance of polyurethane, it is preferable to use an organic diamine. Among them, water is added to an aromatic diamine such as 4,4′-diaminodiphenylmethane or 4,4′-diphenylmethane diisocyanate. It is preferable to convert it to 4,4′-diaminodiphenylmethane.

  For the synthesis of polyurethane, for example, amines such as triethylamine and tetramethylbutanediamine, and metal compounds such as potassium acetate, zinc stearate, titanium tetraethylisopropoxide, and tin octylate may be used as catalysts.

As a weight average molecular weight (Mw) of a polyurethane, 100,000-300,000 are preferable, More preferably, it is 150,000-250,000. By setting the weight average molecular weight (Mw) to 100,000 or more, the film strength of the formed film is improved and the wear resistance is improved. Moreover, by setting it as 300,000 or less, the increase in the viscosity of a polyurethane solution can be suppressed and it can make it easy to impregnate a nonwoven fabric. In addition, the weight average molecular weight of a polyurethane is calculated | required by gel permeation chromatography (GPC), for example, is measured on condition of the following.
Equipment: GPC measuring machine HLC-8020 (manufactured by Tosoh Corporation)
Column: TSK gel GMH-XL (manufactured by Tosoh Corporation)
Solvent: N, N-dimethylformamide (hereinafter abbreviated as DMF)
Standard sample: Polystyrene (TSK standard polystyrene; manufactured by Tosoh Corporation)
Temperature: 40 ° C
Flow rate: 1.0 ml / min The polyurethane used as the main component of the elastic resin binder in the present invention preferably has a gel point of 2.5 ml or more and 6 ml or less. More preferably, it is the range of 3 ml or more and 5 ml or less. In the present invention, the gelation point means that while stirring 100 g of a DMF solution of 1% by weight of polyurethane resin, distilled water is dropped into this solution and the coagulation of the polyurethane starts under a temperature condition of 25 ± 1 ° C. It is the value of the amount of water dripping when clouded. For this reason, it is necessary to use the DMF used for the measurement having a water content of 0.03% or less. The gelation point of polyurethane present in the sheet-like material can be measured by extracting polyurethane from the sheet-like material using DMF and adjusting the polyurethane concentration to 1% by weight. When the polyurethane DMF solution is slightly cloudy in advance, the gel point can be measured by measuring the value of the amount of water dripping when the degree of cloudiness changes after the start of coagulation of the polyurethane.

  This gel point indicates the moisture tolerance when polyurethane is wet-coagulated using a polyurethane DMF solution. A gel with a low gel point has a fast solidification rate and a gel with a high gel point has a solidification rate. It tends to be slow.

  When the gel point is less than 2.5 ml, when the polyurethane resin is wet coagulated, the coagulation rate is too fast, resulting in large and rough polyurethane foaming in the nonwoven fabric internal space, and some poor foaming. As a result, when the surface of the sheet-like material is ground with sandpaper, the length of the napped surface is uneven and the napped quality is very poor. In addition, in the process of applying the polyurethane resin, the polyurethane solution easily gels due to moisture contained in the surrounding air, so that there is a problem such as uneven polyurethane adhesion or piping clogged with the gelled polyurethane resin. This is an undesirable direction because it tends to occur. On the other hand, when the gel point exceeds 6 ml, when the polyurethane resin is wet coagulated, the coagulation rate is too slow, resulting in a small polyurethane foam in the interior space of the nonwoven fabric, and the polyurethane becomes dense. When the film becomes hard and the surface of the sheet-like material is ground with sandpaper or the like, it is difficult to grind polyurethane, and the surface napping is very short and the quality tends to be poor.

  In order to set the gel point of the polyurethane used in the present invention to 2.5 ml or more and 6 ml or less, it depends on the type and amount of the organic diisocyanate and chain extender used in the synthesis of the polyurethane, but is represented by the general formula (1). The weight ratio of the polycarbonate diol having hydroxyl groups at both ends of the molecular chain having a polycarbonate skeleton and the polycarbonate diol having hydroxyl groups at both ends of the molecular chain having the polycarbonate skeleton represented by the general formula (2) is adjusted. Is possible. In order to keep the gel point low in the target gelation range, the ratio of the polycarbonate diol having hydroxyl groups at both ends of the molecular chain having the polycarbonate skeleton represented by the general formula (1) is increased and vice versa. The gel point can be increased by adjusting the ratio of the polycarbonate diol having hydroxyl groups at both ends of the molecular chain having the polycarbonate skeleton represented by the general formula (1).

  The elastic resin binder in the present invention is mainly composed of polyurethane. Here, the main component means that the weight ratio of the entire elastic resin binder is 50% or more. Included are polyester resins, polyamide resins, polyolefin resins, acrylic resins, silicone resins, ethylene-vinyl acetate resins, etc. as long as the binder performance, hydrolysis resistance, light resistance, and texture are not impaired. Various additives, for example, pigments such as carbon black, flame retardants such as phosphorus, halogen, silicone and inorganic, antioxidants such as phenol, sulfur and phosphorus, benzotriazole UV absorbers such as benzophenone, salicylate, cyanoacrylate, oxalic acid anilide, light stabilizers such as hindered amine and benzoate, hydrolysis stabilizers such as polycarbodiimide, plasticizer, antistatic agent , Surfactant, softener, water repellent, coagulation regulator, dyeing Or the like may also contain trace amounts.

In addition, the present invention is a sheet-like material composed of ultrafine fibers having a fineness of 0.5 dtex or less and the polyurethane. Further, the sheet-like material is subjected to forced deterioration treatment under the following condition A, and then subjected to JIS L1096 (2005). Martindale abrasion test (10,000 times friction) specified in the year edition), and the appearance change before and after the friction test is No. 3 or more according to the criteria defined in JIS L1076 (2005 edition), and After the forced deterioration treatment under the following condition B, the Martindale abrasion test (10,000 friction) specified in JIS L1096 (2005 version) was conducted, and the appearance change before and after the friction test was JIS L1076 ( It is characterized in that it is No. 3 or more according to the criteria defined in 2005). Here, the appearance evaluation is performed based on the pilling determination standard photograph 2.
[Forced deterioration treatment condition A]: After applying artificial sebum having the following composition to 8% by weight based on the sheet weight, it was irradiated with light for 144 hours using a xenon arc lamp type light resistance tester stipulated in JIS L0843 B-6 (2005 edition).
[Forced deterioration treatment condition B]: 8% by weight of artificial sebum having the following composition was applied to the sheet weight, and then left in an atmosphere of 70 ° C. and 90% relative humidity for 5 weeks. Artificial sebum composition: stearic acid (15 parts by weight)
Oleic acid (15 parts by weight)
Beef tallow extremely hardened oil (15 parts by weight)
Olive oil (15 parts by weight)
Cetyl alcohol (15 parts by weight)
Paraffin (15 parts by weight)
Cholesterol (5 parts by weight)
Until now, as a method for evaluating the durability of a sheet-like material, the sheet-like material is used alone or after artificial sweat fluid as defined in JIS L0848 (2005 edition) is applied, followed by forced hydrolysis treatment, forced light degradation treatment. It has been done to measure this physical property. However, there is no correlation between the evaluation means and the durability when actually used, and the durability when the sheet-like material is actually used is small even though the deterioration of physical properties when these treatments are performed is small. In some cases, the properties were insufficient.

  Therefore, in the present invention, after applying the artificial sebum, the forced degradation treatment was performed, and it was investigated that durability in actual use and higher correspondence can be taken, and the polyurethane of the present invention. In the case where is used, a sheet-like material having a small change in appearance when the wear test is performed after such forced deterioration has been found to exhibit excellent durability even in actual use.

  Further, in the sheet-like material of the present invention, the elastic resin binder is present in the inner space of the nonwoven fabric formed by entanglement of the fiber bundles of ultrafine fibers, but is not substantially present in the fiber bundles of the ultrafine fibers. It is preferable. If the elastic resin binder is present even inside the fiber bundle, it tends to be difficult to obtain a good texture of the sheet obtained by the voids inside the fiber bundle, and it will be adhered to each ultrafine fiber, so sandpaper When grinding by means of, for example, the fiber existing on the sheet surface is severely cut, and it is difficult to obtain the desired napped length and thereby good quality. Here, the fact that the elastic resin binder substantially does not exist inside the fiber bundle means that the cross section in the thickness direction of the sheet-like material is observed with an SEM, photographed at a magnification of 2000 times, and the inside of the fiber bundle is randomly 50 When more than one part is observed, the binder is not observed in more than half of the parts.

As a method of obtaining a form in which an elastic resin binder mainly composed of polyurethane is present in the interior space of the nonwoven fabric but is not substantially present in the fiber bundle of the ultrafine fibers, polyurethane can be obtained by using dimethylformamide, dimethylacetamide, tetrahydrofuran, dioxane. Make a solution with a solvent such as
(A) After impregnating the above-mentioned polyurethane solution of the present invention into a nonwoven fabric intertwined with the ultra-fine fiber generating type sea-island composite fiber and coagulating it in water or an organic solvent aqueous solution, the sea-island composite A method of dissolving and removing the sea component of the fiber with a solvent that does not dissolve polyurethane,
(B) After the above-mentioned non-woven fabric entangled with the ultra-fine fiber generating type sea-island composite fiber is given polyvinyl alcohol having a saponification degree of preferably 80% or more to protect most of the periphery of the fiber, the sea-island type A method of removing the polyvinyl alcohol after dissolving the sea component of the composite fiber with a solvent in which polyvinyl alcohol does not dissolve, then impregnating the above-described polyurethane solution of the present invention and coagulating in water or an organic solvent aqueous solution.
Etc. can be preferably used.

  In addition, as a form in which the elastic resin binder is present inside the nonwoven fabric, it is a state where at least a part of the single fiber located at the outermost periphery of the fiber bundle of the ultrafine fibers is joined, so that the fibers are not dropped and the peach is less And good texture is obtained. This form can be obtained by the above method (B). That is, since the polyvinyl alcohol protects most of the outer periphery of the microfiber bundle, the polyurethane is prevented from entering the fiber bundle, and the polyurethane adheres to the outer periphery of the fiber bundle that is not partially protected by polyvinyl alcohol. It will be.

  In the sheet-like material of the present invention, the ratio of the elastic resin binder to the sheet-like material is preferably 10% by weight or more and 50% by weight or less, more preferably 15% by weight or more and 35% by weight or less. By making it 10% by weight or more, it is possible to obtain sheet strength and prevent the fibers from falling off, and by making it 50% by weight or less, it is possible to prevent the texture from becoming hard and to achieve the desired good raised quality. Obtainable.

  The sheet-like material of the present invention can be suitably used as a napped leather-like sheet-like material having ultrafine fibers raised on at least one side of the sheet, but raising treatment for forming napped on the sheet surface is It can be applied by a method of grinding the sheet surface using sandpaper, roll sander or the like. In addition, applying a lubricant such as a silicone emulsion or an antistatic agent before the raising treatment tends to obtain elegant napping and make it difficult for grinding powder generated from the sheet-like material to be deposited on the sandpaper by grinding. There is a preferable form.

  Here, the sheet-like material may be obtained by being divided into half or several sheets in the sheet thickness direction before the raising treatment.

  These sheet-like materials, particularly napped leather-like sheet materials obtained by raising ultrafine fibers on at least one side of the sheet, have an elegant appearance and moderate flexibility and texture like natural leather, and are resistant to hydrolysis. It is excellent in light resistance and sweat deterioration resistance, and can be suitably used for applications such as furniture, chairs, wall coverings, and skin materials such as seats, ceilings, and interiors in vehicle interiors such as automobiles, trains, and airplanes.

EXAMPLES Hereinafter, although this invention is demonstrated further more concretely using an Example, this invention is not limited only to a following example.
[Evaluation methods]
(1) Gelation point of polyurethane After the sheet-like material is immersed in DMF for 8 hours to extract the polyurethane from the sheet-like material, the concentration of the obtained polyurethane in DMF solution is measured, and if necessary, DMF is added. A DMF solution having a polyurethane resin concentration of 1% by weight was prepared. While stirring 100 g of a DMF solution having a polyurethane resin concentration of 1% by weight, distilled water was dropped into this solution, and the value of the amount of water dripped when polyurethane coagulation started and became slightly cloudy at a temperature of 25 ± 1 ° C. Was measured. For the measurement, DMF having a water content of 0.03% or less was used. In addition, when the polyurethane DMF solution was slightly cloudy in advance, the value of the amount of water dripping when the degree of cloudiness changed after the start of coagulation of the polyurethane was taken as the gel point.

(2) Ratio of the number of moles of aliphatic hydrocarbons having branched methyl groups contained in polyurethane Extract the polyurethane from the sheet by immersing the sheet in an organic solvent such as DMF, and NMR about the extracted polyurethane The measurement was carried out by comparing the peak of the linear methylene structure with the peak of the branched methyl group structure.

(3) Appearance quality The surface quality of the obtained napped leather-like sheet was evaluated by visual sensory evaluation as follows.
A: Napped length and fiber dispersion state are very good.
○: Napped length and fiber dispersion state are good.
X: Napped length is good, but fiber dispersion is poor.
XX: Napped length is short and defective.
XXX: There is almost no napping and it is a remarkable defect.

(4) Single fiber fineness A cross section of the sheet-like material cut in the thickness direction is observed with a scanning electron microscope (SEM), the fiber diameters of arbitrary 100 ultrafine fibers are measured, and the average value is calculated. It calculated | required in conversion from the specific gravity of the thermoplastic resin currently used for the fiber. In the examples, polyethylene terephthalate having a specific gravity of 1.38 g / cm 3 was used.

(5) Fineness CV
A cross-section of the sheet-like material cut in the thickness direction is observed using a scanning electron microscope (SEM) as an observation surface, the fiber diameter of the ultrafine fibers constituting one bundle of bundle fibers is measured, and the fibers of each ultrafine fiber The fineness of each single fiber was calculated from the diameter and the specific gravity of the fiber component. The same measurement was performed on five bundle fibers, and the average value and the standard deviation value of the single fiber fineness were calculated from these. The average value was defined as the average fineness, and the value obtained by dividing the standard deviation value by the average value as a percentage (%) was defined as the fineness CV.

(6) Weight loss of brushes A circular brush (nylon thread 9700) in which 100 nylon threads having a length of 11 mm and a diameter of 0.4 mm were aligned to form a bundle of 97 concentric circles in a 110 mm diameter circle. The surface of a circular sample (diameter 45 mm) of a napped leather-like sheet was worn under the conditions of a load of 8 pounds (about 3629 g), a rotation speed of 65 rpm, and a rotation frequency of 45 times. The change in weight was defined as brush wear reduction.

(7) Durability (hydrolysis resistance)
The obtained raised leather-like sheet-like material is impregnated with a perchlorethylene solution of artificial sebum having the following composition, drained using a centrifugal dehydrator, and then dried at 80 ° C. for 1 hour using a dryer. It was. Here, the artificial sebum application amount was 8% by weight with respect to the sheet weight. The sheet obtained here was subjected to a forced hydrolysis treatment in which the sheet was left in an atmosphere of 70 ° C. and 95% relative humidity for 10 weeks using a constant temperature and humidity chamber manufactured by Davai Espec. This was subjected to wear evaluation using a Martindale abrasion tester (manufactured by James H. Heal & Co .: Model 406) defined in JIS L1096 (2005 edition). As a standard worn cloth, ABRASIVE CLOTH SM25 made by the same company was used, and a load corresponding to 12 kPa was applied, and the appearance of the sample after being rubbed under the condition of 10,000 wear times was visually observed and evaluated. Evaluation was performed based on the pilling determination standard photograph 2 described in JIS L1076 (2005 edition).
Artificial sebum composition: Stearic acid (15 parts)
Oleic acid (15 parts)
Beef tallow extremely hardened oil (15 parts)
Olive oil (15 parts)
Cetyl alcohol (15 parts)
Paraffin (15 parts)
Cholesterol (5 parts).

(8) Durability (light resistance)
Artificial sebum was given to the obtained napped-toned leather-like sheet-like material by the same method as in (5) above. Here, the artificial sebum application amount was 8% by weight with respect to the sheet weight. Next, forced deterioration treatment using a xenon weather meter manufactured by Suga Test Instruments Co., Ltd., in accordance with JIS L0843 B-6 (2005 edition), irradiates light with a wavelength of 300 to 400 nm with an irradiance of 150 W / m ² for 144 hours. Then, wear evaluation was performed using a Martindale abrasion tester (manufactured by James H. Heal & Co .: Model 406). As a standard worn cloth, ABRASIVE CLOTH SM25 made by the same company was used, and a load corresponding to 12 kPa was applied, and the appearance of the sample after being rubbed under the condition of 10,000 wear times was visually observed and evaluated. Evaluation was performed based on the pilling determination standard photograph 2 described in JIS L1076 (2005 edition).

[Notation of chemical substances]
The meanings of the abbreviations of chemical substances used in Examples and Comparative Examples are as follows.
MDI: 4,4′-diphenylmethane diisocyanate EG: ethylene glycol DMF: N, N-dimethylformamide PHC: polycarbonate diol having a number average molecular weight of 2,000 derived from 1,6-hexanediol POC: 1,8-octanediol Polycarbonate diol having a number average molecular weight of 2,000 derived from PMPC: Polycarbonate diol having a number average molecular weight of 2,000 derived from 3-methyl-1,5-pentanediol PNC: derived from 1,9-nonanediol Polycarbonate diol PDC having a number average molecular weight of 2,000: polycarbonate diol having a number average molecular weight of 2,000 derived from 1,10-decanediol PHMPC-1: 1,6-hexanediol represented by the following general formula (3) 3 Derived from methyl-1,5-pentanediol, these molar ratio (a: b) is 50:50, copolycarbonate diol having a number average molecular weight of 2,000

(In the formula, a and b are positive integers and are random copolymers. R is either (CH ₂ ) ₆ or (CH ₂ ) ₂ —CH (CH ₃ ) — (CH ₂ ) ₂ . Represents an aliphatic hydrocarbon group)
PHMPC-2: derived from 1,6-hexanediol and 3-methyl-1,5-pentanediol represented by the above general formula (3), and the molar ratio (a: b) thereof is 10:90, Copolycarbonate diol PNDC having a number average molecular weight of 2,000: derived from 1,9-nonanediol and 1,10-decanediol represented by the following general formula (4), and the molar ratio (c: d) thereof is 50 : 50, a copolymerized polycarbonate diol having a number average molecular weight of 2,000

(Wherein c and d are positive integers and are random copolymers. R represents an aliphatic hydrocarbon group of either (CH ₂ ) ₉ or (CH ₂ ) ₁₀ )
PTMG: Polytetramethylene glycol PCL having a number average molecular weight of 2,000: Polycaprolactone diol having a number average molecular weight of 2,000.

Example 1
(Manufacture of non-woven fabric)
Sea-island composite fibers were spun at a composite ratio of 55% by weight of sea component and 45% by weight of island component, using polystyrene as the sea component, polyethylene terephthalate as the island component, and a sea-island type composite base having 16 islands. Thereafter, stretching, crimping, and cutting were performed to obtain a nonwoven fabric raw cotton.

  The obtained raw cotton was made into a web using a cross wrapper and made into a nonwoven fabric by needle punching.

  The nonwoven fabric composed of this sea-island type composite fiber was impregnated with a 10% aqueous solution of polyvinyl alcohol having a saponification degree of 87% and then dried. Thereafter, polystyrene as a sea component was extracted and removed from trichlorethylene, followed by drying to obtain a nonwoven fabric composed of ultrafine fibers having a single fiber fineness of 0.1 dtex. The single fiber fineness CV of this nonwoven fabric was 7.3%.

(Manufacture of polyurethane)
POFC as polyol and 50 parts by weight of PHMPC-1; MDI as organic diisocyanate (total amount of polyol: MDI): Four-neck separable with cooling tube using DMF as solvent so that the molar ratio is 1: 3 Prepared in Kolben, stirred and reacted at 40-60 ° C. in a nitrogen atmosphere, and EG as a chain extender was added dropwise at 50-60 ° C. while diluted with DMF, and then diluted gradually with DMF. After about 10 hours, a polyurethane solution having a solid content of 25% was obtained. The gel point of the obtained polyurethane was 4.2 ml.

(Manufacture of sheet-like materials)
The nonwoven fabric composed of the above-mentioned ultrafine fibers is immersed in a polyurethane DMF solution adjusted to a concentration of 12%, and the amount of polyurethane solution attached is adjusted with a squeeze roll. PU was coagulated in an aqueous solution. Thereafter, polyvinyl alcohol and DMF are removed with hot water at 90 ° C., dried, and then immersed in a diluted solution of a silicone-based lubricant (SH7036; manufactured by Toray Dow Corning), and the PU content is 32 wt. % And a silicone content of 0.2% were obtained. One side of this sheet-like material was buffed using 150 mesh and then 240 mesh sandpaper, and dyed with disperse dye to obtain a napped leather-like sheet-like material.

  When the cross section in the thickness direction inside the obtained leather-like sheet was observed with a scanning electron microscope (SEM), polyurethane was not substantially present inside the ultrafine fiber bundle, It was confirmed that the fiber was partially joined to the single fiber located on the outermost periphery. The single fiber fineness CV was 7.5%.

  The obtained napped leather-like sheet-like material had good nap length and dispersibility of fibers and had an elegant appearance. Moreover, it had a good texture with moderate resilience and fullness. The brush wear loss was as small as 10 mg, and the evaluation results of hydrolysis resistance and light resistance were both No. 4 and had excellent durability performance.

Examples 2-5, Comparative Examples 1-4
A napped-toned leather-like sheet was produced in the same manner as in Example 1 except that in the production of polyurethane, the polyol composition and weight ratio were changed to those shown in Table 1, respectively.

  When the cross section in the thickness direction inside the leather-like sheet in each Example / Comparative Example was observed with a scanning electron microscope (SEM), polyurethane was not substantially present inside the ultrafine fiber bundle, It was partially joined to the single fiber located on the outermost periphery of the ultrafine fiber bundle.

  Table 1 shows the compositions and gel points of the polyurethanes of the examples and comparative examples, the appearance quality of the obtained sheet-like material, brush wear reduction, and durability performance.

  Each napped leather-like sheet-like material of Examples 1 to 5 had an elegant appearance quality, and was excellent in brush wear reduction and durability performance. On the other hand, the sheet materials of Comparative Examples 1 to 3 were inferior in appearance quality, and the sheet material of Comparative Example 4 was inferior in brush wear loss and durability.

Claims (9)

In a sheet-like material comprising a nonwoven fabric entangled with ultrafine fibers having a single fiber fineness of 0.5 dtex or less and an elastic resin binder mainly composed of polyurethane present in the internal space, the polyurethane is represented by the following general formula (1): And a sheet-like product having a carbonate structure represented by (2).

(In the formula, R ₁ and R ₂ are straight-chain aliphatic hydrocarbon groups having 8 to 10 carbon atoms, and may be the same or different. X and y are positive integers, and R ₁ and R 2 _{If 2} is different, block copolymerization or random copolymerization)

(Wherein R ₃ and R ₄ are aliphatic hydrocarbon groups having 4 to 6 carbon atoms, which may be the same or different. W and z are positive integers, and R ₃ and R ₄ are When they are different, they are block copolymerization or random copolymerization, and at least one of R ₃ and R ₄ is an aliphatic hydrocarbon group having a methyl group branched) The ratio of the aliphatic hydrocarbon group having a branched methyl group is from 10% to 50% with respect to the total number of moles of R ₁ , R ₂ , R ₃ and R ₄ contained in the polyurethane. The sheet-like material according to claim 1.   The sheet-like material according to claim 1 or 2, wherein the polyurethane has a gelation point of 2.5 ml or more and 6 ml or less. After the sheet material was subjected to forced deterioration treatment under the following condition A, the Martindale abrasion test (10,000 friction) specified in JIS L1096 (2005 version) was performed, and the appearance change before and after the abrasion test was observed. Martindale abrasion test (10) according to JIS L1076 (2005 edition), which is No. 3 or higher and subjected to forced deterioration treatment under the following condition B, and then JIS L1096 (2005 edition) , 1,000 times friction), and the change in appearance before and after the wear test is 3 or more according to the criteria defined in JIS L1076 (2005 edition). The sheet-like material described.
[Forced deterioration treatment condition A]: After applying artificial sebum having the following composition to 8% by weight based on the sheet weight, it was irradiated with light for 144 hours using a xenon arc lamp type light resistance tester stipulated in JIS L0843 B-6 (2005 edition).
[Forced deterioration treatment condition B]: 8% by weight of artificial sebum having the following composition was applied to the sheet weight, and then left in an atmosphere of 70 ° C. and 90% relative humidity for 5 weeks. Artificial sebum composition: stearic acid (15 parts by weight)
Oleic acid (15 parts by weight)
Beef tallow extremely hardened oil (15 parts by weight)
Olive oil (15 parts by weight)
Cetyl alcohol (15 parts by weight)
Paraffin (15 parts by weight)
Cholesterol (5 parts by weight)   The sheet-like article according to any one of claims 1 to 4, wherein the ultrafine fibers are made of polyester.   The non-woven fabric is formed by entanglement of a fiber bundle of ultrafine fibers, and the elastic resin binder is substantially absent inside the fiber bundle of ultrafine fibers. The sheet-like material according to any one of 5.   The sheet-like material according to any one of claims 1 to 6, wherein the elastic resin binder is bonded to at least a part of a single fiber located on the outermost periphery of the fiber bundle of the ultrafine fibers.   The sheet-like article according to any one of claims 1 to 7, wherein the fineness CV of single fibers in the fiber bundle of the ultrafine fibers is 10% or less.   The sheet-like material according to any one of claims 1 to 8, wherein the ultrafine fibers are raised on at least one surface of the sheet-like material.