JP2005009064A - Leather-like sheet and production method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a leather-like sheet having structure which substantially sustains repeated extensional deformations without causing permanent change of its original structure, excellent in elastic stretchability, having soft and dense feel and excellent in appearance without impairing its drapeability. <P>SOLUTION: The leather-like sheet of the present invention comprises an entangled nonwoven fabric which is made of a mixture comprising fibers of an elastic polymer and microfine fibers of an inelastic polymer having an average single fiber fineness of 0.1 dtex or less, wherein the fibers of the elastic polymer are partially porous and are partially fuse-bonded to each other. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a leather-like sheet excellent in stretchability. More specifically, the present invention does not substantially cause structural deformation even when repeatedly stretched and deformed, that is, it has excellent stretchability, form retention, form stability and form recovery, and has a flexible and fulfilling texture. The present invention relates to a leather-like sheet, particularly a napped leather-like sheet having a good appearance and excellent texture, stretchability and drapeability. The present invention also relates to a method for producing the leather-like sheet.

  A napped sheet in which napped fibers are formed on at least one side of a fiber substrate such as a woven or knitted fabric or a non-woven fabric, or a fibrous base body having a foamed structure of an elastic polymer inside, is expressed by the length of napped or the fineness of texture, Since the texture and feel are similar to natural leather suede and nubuck, it has been produced in large quantities in recent years as a suede or nubuck-like napped sheet. In particular, known nappings such as suede or nubuck, in which napped fibers made of ultrafine fiber bundles are present on the surface of a fibrous base material made of entangled nonwoven fabric made of ultrafine fiber bundles and an elastic polymer contained therein. Artificial leather has excellent features such as the grace of the raised surface, soft touch, rich texture, excellent draping characteristics while being lightweight, and no fraying of the cut surface of the fabric base. It is a material that not only resembles natural leather in terms of structure, but also has performance equivalent to or better than that of natural leather in terms of quality.

Further enhance the quality of such napped-toned artificial leather, satisfying all of the characteristics related to appearance, suede or nubuck, etc., soft hand, excellent texture and draping, touch, and comfort. There is a need to provide quality products.
For example, a nonwoven fabric obtained by entanglement of a fiber made of an elastic polymer (elastic fiber) and a fiber made of a non-elastic polymer (non-elastic fiber) in order to obtain a napped artificial leather having elasticity and excellent texture An entangled nonwoven fabric excellent in stretchability, which is contracted by 10 to 80% in area ratio, is known (see, for example, Patent Document 1). However, the artificial leather obtained from the proposed elastic fiber and non-elastic fiber is excellent in drape because the elastic fiber is all in the fiber state and is flexible. Since the binder effect to be retained was small, the passing through the raising process by buffing or the like was poor, the fluffiness was rough, and the appearance of the suede or nubuck was far from it.

In addition, artificial leather using a composite fiber that generates two or more types of elastic fibers having different melting points and an ultrafine non-elastic fiber generating fiber has been proposed (for example, patent literature). 2). However, the low-melting point elastic fiber constituting the artificial leather melts only to give a low binder effect, and the binder effect is insufficient. And these methods could not produce artificial leather with a suede-like appearance.
In addition, impregnating polyurethane into a nonwoven fabric consisting only of sea-island fibers that generate inelastic ultrafine fibers, removing the sea components by solvent extraction, etc. to generate inelastic ultrafine fibers, and then dyeing treatment results in excellent appearance It has been proposed that an artificial leather can be obtained (see, for example, Patent Document 3). However, since elastic fibers are not contained in the nonwoven fabric, structural changes occur when repeated elongation and deformation are performed. Moreover, since the impregnated polyurethane resin is present in the form of a foamed sheet inside the nonwoven fabric, an artificial leather excellent in soft hand, texture and drapeability could not be obtained.

Japanese Patent Publication No. 01-41742 Japanese Examined Patent Publication No. 03-16427 Japanese Patent Publication No. 05-65627

  In the methods described in Patent Document 1 and Patent Document 2, stretchability is obtained, but a fiber raised surface having an excellent appearance cannot be obtained. Further, according to the method described in Patent Document 3, an excellent appearance can be obtained, but it has been difficult to obtain excellent stretchability, texture and drape.

  An object of the present invention is a leather-like sheet comprising a fiber-entangled nonwoven fabric in which fibers made of an elastic polymer and ultrafine fibers made of an inelastic polymer are mixed, and has excellent stretchability, texture, and drapeability, and a method for producing the same, and The object is to provide a raised leather-like sheet having an excellent appearance.

As a result of intensive investigations, the present inventors have formed an entangled nonwoven fabric from elastic fibers and inelastic ultrafine fibers that are partially porous, and the elastic fibers are partially fused. The inventors have found that this structure can be achieved by using the above structure, and have reached the present invention.
That is, the present invention relates to a leather-like sheet having an entangled nonwoven fabric in which fibers made of an elastic polymer and ultrafine fibers made of an inelastic polymer having an average single fiber fineness of 0.1 dtex or less are mixed, and the fibers made of the elastic polymer are partially Further, the present invention relates to a leather-like sheet characterized in that it is in a porous state and the fibers made of the elastic polymer are partially fused.
It is preferable that the fibers made of the elastic polymer are partly fused to form a part of a network structure, and a structure in which ultrafine fibers made of a non-elastic polymer and fibers made of an elastic polymer are partly adhered It is preferable to have.
Furthermore, the present invention relates to a napped leather-like sheet in which napped fibers mainly composed of ultrafine fibers made of an inelastic polymer are formed on at least one surface of the leather-like sheet.

Moreover, this invention relates to the manufacturing method of the leather-like sheet | seat characterized by performing the process of the following I-IV sequentially.
I. From a non-elastic polymer having an average single fiber fineness of 0.1 dtex or less and a fiber (A) capable of generating a fiber made of an elastic polymer, wherein at least a part of the fiber-forming component made of an elastic polymer is exposed on at least a part of the surface A process for producing an entangled nonwoven fabric comprising fibers (B) capable of generating ultrafine fibers,
II. Impregnating the entangled nonwoven fabric with a liquid containing at least a good solvent for the elastic polymer, and partially dissolving the elastic polymer in the fiber (A);
III. Impregnating the entangled nonwoven fabric with a liquid containing at least a poor solvent for the elastic polymer, thereby converting the partially dissolved elastic polymer into a partially porous elastic polymer; and
IV. Converting the fibers (A) and the fibers (B) into fibers made of an elastic polymer and ultrafine fibers made of an inelastic polymer having an average single fiber fineness of 0.1 dtex or less, respectively;

  In the leather-like sheet of the present invention, the elastic fibers are partially porous, and the elastic fibers are partially fused. Therefore, even if the elastic fibers are repeatedly stretched and deformed, the structural change does not substantially occur. In addition, it has excellent stretchability, form retention, form stability, and form recoverability, and has a soft and fulfilling texture. By using the leather-like sheet, it is possible to produce a raised leather-like sheet having a good appearance and excellent texture, stretchability and drape.

Next, the present invention will be described in detail.
Fiber made of elastic polymer (elastic fiber) is melt-spun by elastic polymer alone or melted by combining elastic polymer and at least one kind of spinnable polymer having different chemical or physical properties. It is obtained by dividing the spun multicomponent fiber or by extracting and removing at least one polymer from the multicomponent fiber. The multi-component fiber is a fiber (hereinafter simply referred to as fiber (A)) in which an elastic fiber-forming component is present on at least a part of its surface, and elastic fiber can be generated by division, extraction operation, or the like. . The fiber (A) is not particularly limited as long as it is a composite fiber having a structure in which an elastic polymer is present on a part of its surface, but sea island type fibers, split type fibers and the like are preferable. Among these, sea-island type fibers are more preferable, and sea-island type mixed spun fibers are more preferable because elastic polymers are likely to be randomly present as island components on a part of the surface of the fiber. On the surface of the fiber (A), the area ratio occupied by the elastic polymer is preferably 0.1 to 95%, and more preferably 1 to 70%. If it is 0.1% or more, the elastic fibers are easily made partially porous, and a partially fused state between the elastic fibers is easily obtained. Moreover, the fall of process passability, such as card passability resulting from the property of an elastic polymer, can be prevented as it is 95% or less.

  Examples of the elastic polymer include at least one selected from polymer polyols having a number average molecular weight of 500 to 3500 such as polyester polyol, polyether polyol, polyester ether polyol, polylactone polyol, and polycarbonate polyol, and 4,4′-. Aromatic, alicyclic, and aliphatic organic polyisocyanates such as diphenylmethane diisocyanate, tolylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, hexamethylene diisocyanate, and 1,4-butanediol; Polyurethanes obtained by reacting with a chain extender having two active hydrogen atoms such as ethylenediamine; polyester elastomers, polyetherester elastomers, etc. Elastomers; Polyamide elastomers such as polyetheresteramide elastomer and polyesteramide elastomer; Conjugated diene polymers such as polyisoprene and polybutadiene; Block copolymers having conjugated diene polymer blocks such as polyisoprene and polybutadiene in the molecule Polymers; and elastomers having rubber elastic behavior that can be melt-spun. Among them, polyurethanes are most preferable in view of high flexibility, low resilience and high friction resistance, high adhesion to non-elastic ultrafine fibers, and excellent heat resistance and durability.

  It should be noted that an additive such as a pigment such as carbon black or a thermal stability improver of the resin can be added to the elastic polymer within a range not impairing the effects of the present invention.

  The sea component polymer (the polymer to be extracted or decomposed and removed) of the fiber (A) which is a multicomponent fiber needs to be different from the island component polymer in solubility in a solvent or decomposability in a decomposing agent. For example, the solubility or decomposability is larger than the island component polymer, the compatibility or affinity with the island component polymer is small, and the melt viscosity is smaller than the melt viscosity of the island component polymer, or the surface tension of the island component polymer is A polymer having a surface tension smaller than that is preferably used as the sea component polymer. Examples of such polymers include easily soluble polymers such as polyethylene, polystyrene, modified polystyrene, and ethylene propylene copolymer, and easily modified (copolymerized) polyethylene terephthalate modified with sodium sulfoisophthalate and polyethylene glycol. Examples thereof include melt-spinnable polymers such as degradable polymers.

  Does an ultrafine fiber made of an inelastic polymer (inelastic ultrafine fiber) divide a multicomponent fiber made of an inelastic polymer and at least one spinnable polymer having different chemical or physical properties from the inelastic polymer? Alternatively, it can be obtained by extracting and removing at least one kind of polymer from the multicomponent fiber. The multicomponent fiber is a fiber that can generate an inelastic ultrafine fiber having an average single fiber fineness of 0.1 dtex or less by splitting, extraction operation, or the like (hereinafter sometimes simply referred to as fiber (B)). The fiber (B) is not particularly limited as long as it is a composite fiber capable of generating an inelastic ultrafine fiber having an average single fiber fineness of 0.1 dtex or less, but sea island type fibers, split type fibers and the like are preferable. The content of the inelastic polymer in the fiber (B) is preferably 10 to 90% by mass, and more preferably 30 to 70% by mass.

  Examples of non-elastic polymers include melt-spinnable polyamides such as nylon-6, nylon-66, nylon-10, nylon-11, nylon-12, and copolymers thereof; polyethylene terephthalate, polytrimethylene terephthalate, Examples thereof include melt-spinnable polyesters such as polybutylene terephthalate and cationic dyeable modified polyethylene terephthalate; and melt-spinnable polyolefins such as polypropylene and copolymers thereof. You may use the said polymer individually or in mixture of 2 or more types of polymer.

When the fiber (B) is a sea-island type fiber, the inelastic polymer constituting the island component needs to be separated into microfibers without unnecessarily fusing the generated inelastic ultrafine fibers. Therefore, when both the fiber (A) and the fiber (B) are sea-island fibers, an inelastic polymer is selected so that at least the inelastic ultrafine fibers are not fused together by solvent treatment for extracting and removing sea components. It is preferable to do. Specifically, a polymer having a solvent swelling rate of 10% by mass or less in the sea component removal treatment is preferable.
In addition, an additive such as a pigment typified by carbon black or the like or a thermal stability improver of a resin can be added to the inelastic polymer as long as the effects of the present invention are not impaired.

The sea component polymer of the fiber (B) is basically the same as that of the fiber (A), and the polymers described for the fiber (A) can be used. The sea component of the fiber (B) and the fiber (A) may be different polymers. However, in order to efficiently remove the sea component, the same kind of polymer is preferable.
From the viewpoint of melt spinning stability, it is preferable to select a polymer having a melting point suitable for the melt spinning temperature of the elastic polymer as the non-elastic polymer, the polymer constituting the sea component of the fiber (A) and the fiber (B). . For example, when polyurethane is used as the elastic polymer, the melting point of the non-elastic polymer and the polymer constituting the sea component is about 230 ° C. or less, and when using a polyester elastomer or polyamide elastomer as the elastic polymer, it is non-elastic. The melting point of the polymer and the polymer constituting the sea component is preferably selected to be about 260 ° C. or lower.

  The fiber (A) and the fiber (B) can be obtained by a known spinning method, and are made into a nonwoven fabric by a known method. For example, after drawing the fiber (A) and the fiber (B), crimping, cutting and applying an oil agent are applied, and after blending (mixing) at a desired ratio, the card is defibrated and a web is formed through the webber. . In this case, the blend ratio of the fibers (A) and fibers (B) is such that the mass ratio of elastic polymer: inelastic polymer is 20:80 to 80:20. It is preferable in terms of excellent stretchability and texture, and is preferable in that the napped state of the napped leather-like sheet is good. When the ratio of the elastic polymer is 20% by mass or more, the stretchability of the obtained leather-like sheet is improved, and when it is 80% by mass or less, it is possible to avoid the effect of raising the hair from being hardly expressed, Furthermore, it is possible to prevent an insufficient napped state from being rubber-like.

  Next, the obtained web is laminated to a desired weight and thickness, and then entangled with a known method such as needle punching or high-speed water flow to obtain an entangled nonwoven fabric. The entangled nonwoven fabric is preferably heat-treated at a temperature in the range of 50 to 150 ° C. or heat-treated with hot water in the range of 50 to 95 ° C. to obtain excellent stretchability. The shrinkage rate is determined by the fiber type, the mass ratio of the elastic polymer and the non-elastic polymer, the spinning conditions and the stretching conditions of the fibers (A) and (B). The area shrinkage ratio of the entangled nonwoven fabric is 5 to 5 in that the appearance and stretchability of the obtained leather-like sheet are improved, and further, the structure of the leather-like sheet is hardly changed even after repeated elongation and deformation. A range of 50% is preferable.

Further, if necessary, the entangled nonwoven fabric may be temporarily fixed with a resin that can be dissolved and removed, such as a water-soluble paste such as a polyvinyl alcohol resin. Moreover, you may heat-press the surface of this entangled nonwoven fabric by a well-known method from the point which improves the smoothness of a surface and provides the lighting effect which was further excellent in the napped-toned leather-like sheet.
The thickness of the obtained entangled nonwoven fabric can be arbitrarily selected depending on the use of the leather-like sheet and is not particularly limited, but in the case of one layer, it is preferably about 0.2 to 10 mm, More preferably, it is about 0.4 to 5 mm. Density is preferably ^{0.20~0.65g / cm 3, 0.25~0.55g / cm} 3 is more preferable. When it is 0.20 g / cm ³ or more, it is possible to avoid the feeling of napping of the fibers and further to lower the mechanical properties. It can avoid that the texture of the leather-like sheet | seat obtained as it is 0.65 g / cm < ³ > or less becomes hard.

Next, the entangled nonwoven fabric is impregnated with a treatment liquid A containing at least a solvent for the elastic polymer, and the elastic polymer (elastic fiber forming component) present on the surface and end face of the fiber (A) is partially dissolved. Next, the treatment liquid B containing at least a non-solvent for the elastic polymer is impregnated to solidify the dissolved elastic polymer into a porous state, and at the same time, the fibers (A) are partially fused via the elastic polymer.
Examples of the solvent for the elastic polymer include, when the elastic polymer is polyurethane, good solvents for polyurethane such as N, N-dimethylformamide (DMF), dioxane, alcohols, etc., among which DMF is preferable. The treatment liquid A may be a combination of a good solvent and a poor solvent for the elastic polymer, and may contain the elastic polymer at a low concentration. The concentration of the elastic polymer is preferably 1 to 30% by mass and more preferably 1 to 10% by mass in terms of solid content. If it is 30% by mass or less, although depending on the amount of impregnation, the elastic fiber and / or inelastic ultrafine fiber is fixed by the elastic polymer and loses flexibility, and the drapeability and stretchability of the resulting leather-like sheet are reduced. Can be prevented.

When the treatment liquid A contains an elastic polymer, for example, at least one polymer diol having an average molecular weight of 500 to 3000 selected from polyester diol, polyether diol, polyether ester diol, polylactone polyol, polycarbonate diol, and the like, and 4 , 4'-diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate and other aromatic, alicyclic, and aliphatic organic polyisocyanates, and 2 such as ethylene glycol and ethylenediamine Polyurethane obtained by reacting at least one low molecular weight compound having one or more active hydrogen atoms in a predetermined molar ratio is preferably used as the elastic polymer. Moreover, you may add polymers, such as a synthetic rubber and a polyester elastomer, to a polyurethane as needed. In the treatment liquid A containing an elastic polymer, additives such as a colorant, a coagulation regulator, and an antioxidant may be blended as necessary.
When the treatment liquid A contains an elastic polymer, the mass ratio of the elastic polymer in the impregnated treatment liquid A and the total amount of the elastic polymer contained in the entangled nonwoven fabric is preferably 0.2 / 100 to 30/100, 0.5 / 100 to 10/100 is more preferable. When the mass ratio is 30% by mass or less, the stretchability, texture, and drapeability of the obtained leather-like sheet can be prevented from decreasing.

Examples of the non-solvent of the elastic polymer include a poor solvent for polyurethane such as water when the elastic polymer is polyurethane. The impregnated nonwoven fabric is impregnated with the treatment liquid A and then impregnated with the treatment liquid B, whereby the partially dissolved elastic polymer is solidified in a porous state. When solidifying, the dissolved elastic polymers respectively present in different places are partially fused together, and the fiber (A) is partially fused. The ratio of the elastic solvent forming component existing on the surface of the fiber (A) is increased by a known spinning method, the amount of the treatment liquid A impregnated is increased, and the ratio of the good solvent to the elastic polymer in the treatment liquid A is further increased. It is preferable to adjust the number of fusion points between the fibers (A) by increasing the number of the fibers (A) to partially generate a network structure.
Here, the porous state means a fine sponge state formed when the elastic polymer is wet-solidified. When the elastic fiber generated from the fiber (A) is partially porous, the texture and drape of the resulting leather-like sheet are excellent.
Examples of the method for impregnating the treatment liquid A include known methods such as an immersion method, a gravure method, and a spray method. Among them, the dipping method is preferably used in that it can be sufficiently impregnated into the entangled nonwoven fabric and, moreover, can be sufficiently adhered to the surface of the fiber (A).

  By impregnating the entangled nonwoven fabric with the treatment liquid A, the elastic fiber-forming component exposed on the surface or end face of the fiber (A) is partially dissolved. In order to avoid unnecessary dissolution, the treatment with the treatment liquid A is preferably performed at 10 to 60 ° C. for 30 seconds to 4 minutes. Immediately after the treatment or after removing the excess treatment liquid A, the treatment liquid B is impregnated. The treatment liquid B can be impregnated by the method described for the treatment liquid A. The treatment with the treatment liquid B is preferably performed at 25 to 50 ° C. for 10 to 30 minutes, and the impregnation amount of the treatment liquid B is 100 parts by mass or more with respect to 100 parts by mass of the total elastic polymer contained in the entangled nonwoven fabric. It is preferable in terms of the solidification stability of the elastic fiber forming component.

  The entangled nonwoven fabric is treated with the treatment liquid A and the treatment liquid B as described above and then dried, and then elastic fibers and inelastic ultrafine fibers are generated from the fibers (A) and fibers (B). When the fiber (A) and the fiber (B) are sea-island type fibers, it is preferably treated with a liquid that dissolves or decomposes sea components by a method such as immersion. For example, when the sea component is polyethylene or polystyrene, toluene is used, and when the sea component is an easily alkali-degradable polyester, an aqueous caustic soda solution is used. The amount of the dissolved or decomposed solution used is preferably 100 parts by mass or more with respect to 100 parts by mass of the total amount of the sea component polymer, the treatment temperature is preferably 5 to 50 ° C., and the treatment time is preferably 5 to 40 minutes. .

  By this treatment, the sea component is removed from the fiber (A) and the fiber (B). The fibers (A) are converted into elastic fibers that are partially porous. The generated elastic fibers are partially fused together to form a network structure. The fiber (B) is transformed into an inelastic ultrafine fiber or a fiber bundle thereof. The elastic fiber and the inelastic ultrafine fiber may be partially adhered by reducing the sea component ratio of the fiber (A) and the fiber (B) or exposing the island component to the surface by a known spinning technique. preferable. The average single fiber fineness of the elastic fiber generated from the fiber (A) is preferably 0.01 to 2 dtex, and more preferably 0.01 to 0.5 dtex. Moreover, the average single fiber fineness of the inelastic ultrafine fiber generated from the fiber (B) is 0.1 dtex or less, preferably 0.001 to 0.05 dtex. When the average single fiber fineness exceeds 0.1 dtex, the appearance of napped hair becomes rough, and further, a high-class feeling such as natural leather-like touch and texture cannot be obtained.

  In the present invention, “elastic fiber is partially porous” means that after extracting or decomposing and removing non-elastic ultrafine fibers, the surface of the leather-like sheet or a slice plane parallel to the surface is observed with a scanning electron microscope. The state where 10 to 100% of the surface of the elastic fiber has a porous structure.

“Fusion of elastic fibers” refers to a state in which elastic fibers are partially bonded by melting of an elastic polymer. The degree of fusion of the elastic fiber is evaluated by the density of the fused part. When observed with a scanning electron microscope in the same manner as described above, the density of the fused portions is preferably 1 to 10 locations / 2 mm ² , and more preferably ² to 8 locations / 2 mm ² . Within the above range, even if the obtained leather-like sheet is repeatedly stretched and deformed, the structural change hardly occurs and the stretchability is excellent.

Further, the “network structure” means that at least one other elastic fiber is fused two-dimensionally or three-dimensionally in a branch shape to one elastic fiber, and the at least one other elastic fiber is Furthermore, it refers to a structure in which it is fused or in contact with another elastic fiber. The existence ratio of the network structure is evaluated by the existence density. When observed with a scanning electron microscope in the same manner as described above, the density of the structure is preferably 1 to 50 locations / 5 mm ² , and more preferably 2 to 40 locations / 5 mm ² . Within the above range, even if the obtained leather-like sheet is repeatedly stretched and deformed, structural deformation hardly occurs and the stretchability is excellent.

Hereinafter, the partial porous state of the elastic fiber, the partial fusion of the elastic fiber, and the partial network structure will be further described with reference to the drawings.
FIG. 1 is a drawing-substituting electron micrograph showing a cross section of the leather-like sheet of the present invention after removing only inelastic ultrafine fibers. In FIG. 1, reference numeral 2 represents an elastic fiber, and reference numeral 1 represents a partially porous state of the elastic fiber. Reference numeral 3 indicates a fused position of the elastic fiber. FIG. 2 is a drawing-substituting electron micrograph showing the surface of the leather-like sheet of the present invention after removing only inelastic ultrafine fibers. Reference numerals 1 to 3 in FIG. 2 represent the same contents as in FIG. 1 and 2, in the leather-like sheet of the present invention, the elastic fibers constitute an entangled nonwoven fabric structure, the elastic fibers are partially porous, and the elastic fibers are partially melted. It can be confirmed that the mesh structure is partially formed and that the network structure is partially formed by the partial fusion.

  FIG. 3 is a drawing-substituting electron micrograph showing a cross-section after removing only inelastic ultrafine fibers from a conventional leather-like sheet made of entangled nonwoven fabric composed only of inelastic ultrafine fibers and an elastic polymer impregnated therein. It is. FIG. 4 is a drawing-substituting electron micrograph showing the surface after removing only inelastic ultrafine fibers from the conventional leather-like sheet. As apparent from FIGS. 3 and 4, unlike the leather-like sheet of the present invention, in the conventional leather-like sheet, the elastic polymer exists in the form of a sheet, and the elastic polymer sheet is entirely porous. It has become.

  The leather-like sheet obtained by making the entangled nonwoven fabric ultrafine may be sliced into a plurality of sheets in a direction parallel to the main surface, if necessary. By raising the surface of at least one surface of the leather-like sheet to form a raised surface mainly composed of ultrafine fibers, a raised leather-like sheet can be obtained. The napped surface is formed by a known method such as buffing with a sand paper. Applying a good solvent for elastic polymer, a solvent or a solution combining a good solvent and a poor solvent or a known binder resin, etc. to the surface by a gravure treatment, spray treatment, coater treatment, etc. By fixing the elastic fiber present in the fiber, it becomes easy to form napped fibers mainly composed of inelastic ultrafine fibers. Such a treatment before the raising treatment is preferable because the writing property and the surface touch become more excellent.

  The napped leather-like sheet thus obtained is, as described above, that the elastic fibers are partially porous, that the elastic fibers are partially fused together, A non-elastic ultrafine fiber is formed on at least one surface of a leather-like sheet, wherein the network structure is partially formed by partial fusion, and the nonelastic ultrafine fiber and the elastic fiber are partially adhered to each other. Since napped hairs are mainly formed, they have good stretchability, texture and drapeability that are not found in conventional leather-like sheets, and are excellent in surface touch, lighting effect and appearance. Furthermore, it can also be set as a grained leather-like sheet by forming a coating layer on one side of the leather-like sheet. The leather-like sheet of the present invention can be applied to a wide range of uses such as clothing, furniture, shoes and bags. In particular, the leather-like sheet of the present invention is particularly useful in the field of high-grade silver products and high-grade suede products.

Next, embodiments of the present invention will be described by way of examples, but the present invention is not limited to these examples.
In the examples, “part” and “%” relate to mass unless otherwise specified. Moreover, the measurement of average single fiber fineness and each evaluation were performed as follows.

(1) Average single fiber fineness The surface or cross section of the leather-like sheet was observed with an electron microscope at a magnification of about 500 to 2000 times to measure the fiber diameter, and the single fiber fineness (decitex) was obtained from the measured value. .

(2) Feeling of napping, uniformity of napping, color spots, texture The raised surface of the dyed napped leather-like sheet obtained in the following Examples or Comparative Examples by those engaged in the manufacture and sale of artificial leather Was evaluated by touching with a hand. Natural leather suede-like smooth appearance, touch and texture were evaluated as A, natural leather suede was slightly inferior to practical use but B was not practically problematic, and case was inferior to natural leather suede and poor in commercial value as C.

Example 1
Poly-3-methyl-1,5-pentaneadipate glycol having an average molecular weight of 2,000, 4,4′-diphenylmethane diisocyanate, polyethylene glycol and 1,4-butanediol so that the nitrogen percentage based on isocyanate is 4.3% Polyester polyurethane was obtained by melt polymerization. The melt viscosity was 5000 poise. 50 parts of the above polyester-based polyurethane pellets (island component elastic polymer) and 50 parts of low-density polyethylene pellets (sea component) dried to a water content of 50 ppm or less are melt-kneaded with a screw kneader, melt-spun at 230 ° C., and a fineness of 14 dtex. A sea-island type mixed spun fiber (A ₀ ) in which polyurethane is partially present on the surface was obtained. Also, 50 parts of nylon-6 pellets (island component inelastic polymer) and 50 parts of polyethylene pellets (sea component) are melt-kneaded with a screw kneader, melt-spun at 280 ° C., and sea-island mixed spun fiber having a fineness of 10 dtex. (B ₀ ) was obtained. Fiber (A ₀ ) and fiber (B ₀ ) are blended (mixed) so that the mass ratio of the polyester polyurethane fiber and nylon fiber after ultrathinning is 40:60, and co-stretched 2.5 times. Then, crimped and cut to obtain staple fibers in which 7 dtex fibers (A ₁ ) and 4 dtex fibers (B ₁ ) each having a fiber length of 51 mm were mixed (mixed).

Next, after the mixed cotton fiber (mixed fiber) is defibrated with a card, it is made into a web with a cross wrap webber and processed with 1500 punch / cm ² with a needle needle of 1 barb, whereby an intertwined nonwoven fabric having a basis weight of 800 g / m ² ( I). This entangled nonwoven fabric (I) was contracted by hot water at 95 ° C. by an area ratio of 30% to obtain an entangled nonwoven fabric (II). Then, after impregnating a water-based polyurethane emulsion composition containing a polyether polyurethane solid content concentration of 2% (amount of polyurethane applied to the entangled nonwoven fabric (II) 1%) and heat treatment, the entangled nonwoven fabric (II ) Is dried and dried in a dryer to soften the sea component polyethylene and partially bond the fibers to have a thickness of 2.63 mm, a weight per unit area of 1040 g / m ² and a density of 0.395 g / cm ^3. A good entangled nonwoven fabric (III) was obtained.

Next, the entangled nonwoven fabric (III) is impregnated with a 4% DMF solution of polycarbonate-based polyurethane, poured into a 30% aqueous solution of DMF at 40 ° C., and further washed with water to be present in the entangled nonwoven fabric (III). DMF was removed (porosification treatment). Next, the polyethylene in the fiber (A ₁ ) and the fiber (B ₁ ) is dissolved and removed in a hot toluene bath at 90 ° C. (ultrafine fiber treatment), and after drying, a leather-like sheet (I )
The average single fiber fineness of the nylon ultrafine fibers of the obtained leather-like sheet (I) is 0.01 dtex, and the surface and the cross section are observed with an electron microscope. As a result, the polyurethane fibers (elastic fibers) are partially porous. Furthermore, the polyurethane fibers were partially fused to form a part of the network structure. Furthermore, the polyurethane fibers were in close contact with some nylon ultrafine fibers (inelastic ultrafine fibers).

  This leather-like sheet (I) was divided into two along the main surface, and the divided surface was ground by a buffing machine to obtain a leather-like sheet (II) having a thickness of 0.50 mm. The surface opposite to the split surface of the leather-like sheet (II) was brushed with sandpaper of abrasive grain count # 400 to obtain an undyed napped leather-like sheet. Next, the raised leather-like sheet was dyed under the following conditions.

Dyeing machine Wins dye Ilgaran Brown 2RL (manufactured by Ciba Specialty Chemicals) owf 4%
Ilgaran Yellow 2GL (Ciba Specialty Chemicals Co., Ltd.) owf 1%
Auxiliary agent Leberan NK-D (manufactured by Maruhishi Oil Chemical Co., Ltd.) 2g / L
Bath ratio 1:20
Dyeing time 60 minutes at 90 ° C

  After brushing the napped leather-like sheet dyed brown, the brown napped leather-like sheet excellent in draping property was obtained by stretching the hair with a brushing roll. The obtained napped leather-like sheet was excellent in stretchability, and no structural change occurred even when the 30% elongation was repeated 10 times. In addition, it had a soft and fulfilling texture and excellent drape. The other evaluation results are shown in Table 1.

Comparative Example 1
A leather-like sheet (I) having a thickness of about 1.3 mm was obtained in the same manner as in Example 1 except that the entangled nonwoven fabric (III) was not made porous. As a result of observing the surface and cross section of the obtained leather-like sheet (I) with an electron microscope, the elastic fibers are in a non-porous state, and the elastic fibers are not fused together to form a network structure. It wasn't good.
The leather-like sheet (I) was divided into two along the main surface, and the divided surface was ground with a buffing machine to obtain a leather-like sheet (II) having a thickness of 0.52 mm. The surface opposite to the split surface of the leather-like sheet (II) was brushed with sandpaper having an abrasive grain number # 400 to obtain an undyed napped-toned leather-like sheet. The obtained napped leather-like sheet had an unstable napped state and low processability. The obtained napped leather-like sheet was dyed under the same conditions as in Example 1. As a result, a velor napped leather-like sheet that was dyed brown, had a poorly raised feeling and a rough appearance, and had a non-uniform raised edge. Obtained. The obtained napped leather-like sheet was excellent in drape and stretchability, but the structure changed when 30% elongation was repeated about 10 times, and the texture was soft but lacked in fullness. The other evaluation results are shown in Table 1.

Comparative Example 2
A raw cotton consisting only of 4 dtex fiber (B ₀ ) is defibrated with a card, made into a web with a cross wrap webber, and then treated with 1500 punch / cm ² with a needle needle of 1 barb, whereby the basis weight is 800 g / m ^2. Of entangled nonwoven fabric (I) was obtained. The entangled nonwoven fabric (III) having a thickness of 2.65 mm, a basis weight of 850 g / m ² and a density of 0.32 g / cm ³ was obtained by heat-treating with a dryer and softening the sea component polyethylene to partially bond the fibers. The entangled nonwoven fabric (III) is impregnated with a 13% DMF solution of polyether polyurethane, coagulated with a 30% DMF aqueous solution, washed with water and dried, and dried from ultrafine nylon 6 fibers and polyurethane foam sheet. A leather-like sheet (I) was obtained. The average single fiber fineness of the obtained ultrafine fibers is 0.01 dtex, and the surface and cross section were observed with an electron microscope. As a result, the fibers had no porous structure, and the fibers were partially fused together. No network structure was observed.
This leather-like sheet (I) was divided into two along the main surface, and the divided surface was ground using a buffing machine to obtain a leather-like sheet (II) having a thickness of 0.50 mm. The surface opposite to the split surface of the leather-like sheet (II) was subjected to napping # 400 sandpaper napping to obtain an undyed napped leather-like sheet. The napped leather-like sheet was dyed under the same conditions as in Example 1 to obtain a brown napped leather-like sheet. Although the obtained napped leather-like sheet was excellent in appearance, it was inferior in elasticity and changed in structure as a result of repeating 30% elongation 10 times. The other evaluation results are shown in Table 1.

Table 1
Thickness Per unit density Density of hair napping Uniformity of hair raising Color spots Texture
mm g / m ² g / cm ³
Example 1 0.50 218 0.43 A A A A
Comparative Example 1 0.52 218 0.42 C CA A A
Comparative Example 2 0.50 190 0.38 A A B B

The drawing substitute electron micrograph which shows the cross section of the leather-like sheet | seat of this invention after removing only an inelastic ultrafine fiber. The drawing substitute electron micrograph which shows the surface of the leather-like sheet | seat of this invention after removing only an inelastic microfiber. The drawing substitute electron micrograph which shows the cross section after removing only an inelastic ultrafine fiber from the conventional leather-like sheet | seat consisting of the entangled nonwoven fabric which consists only of an inelastic ultrafine fiber, and the elastic polymer impregnated in this. The drawing substitute electron micrograph which shows the surface after removing only an inelastic ultrafine fiber from the conventional leather-like sheet | seat consisting of the entangled nonwoven fabric which consists only of an inelastic ultrafine fiber, and the elastic polymer impregnated in this.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Elastic fiber partially porous 2 Elastic fiber 3 Fusion part of elastic fibers

Claims (5)

In a leather-like sheet having an entangled nonwoven fabric in which fibers made of an elastic polymer and ultrafine fibers made of an inelastic polymer having an average single fiber fineness of 0.1 dtex or less are mixed, the fibers made of the elastic polymer are partially porous. Furthermore, the leather-like sheet | seat characterized by the fibers which consist of this elastic polymer being partly melt | fused. 2. The leather-like sheet according to claim 1, wherein fibers made of an elastic polymer are partially fused to partially form a network structure. The leather-like sheet according to claim 1 or 2, wherein ultrafine fibers made of an inelastic polymer and fibers made of an elastic polymer are partially fused. A napped-toned leather-like sheet, wherein napped fibers mainly composed of ultrafine fibers made of an inelastic polymer are formed on at least one surface of the leather-like sheet according to any one of claims 1 to 3. A method for producing a leather-like sheet comprising sequentially performing the following steps I to IV.
I. From a non-elastic polymer having an average single fiber fineness of 0.1 dtex or less and a fiber (A) capable of generating a fiber made of an elastic polymer, wherein at least a part of the fiber-forming component made of an elastic polymer is exposed on at least a part of the surface A process for producing an entangled nonwoven fabric comprising fibers (B) capable of generating ultrafine fibers,
II. Impregnating the entangled nonwoven fabric with a liquid containing at least a good solvent for the elastic polymer, and partially dissolving the elastic polymer in the fiber (A);
III. Impregnating the entangled nonwoven fabric with a liquid containing at least a poor solvent for the elastic polymer, thereby converting the partially dissolved elastic polymer into a partially porous elastic polymer; and
IV. Converting the fibers (A) and the fibers (B) into fibers made of an elastic polymer and ultrafine fibers made of an inelastic polymer having an average single fiber fineness of 0.1 dtex or less, respectively;

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