JP2005188008A - Nubuck-like artificial leather - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nubuck-like artificial leather having shorter fluff and a feeling of more fineness, when compared with those of conventional suede-like artificial leathers. <P>SOLUTION: This nubuck-like artificial leather is composed of four layers in total so that a second intermediate layer given by three-dimensionally entangling ultrafine fibers having a size of ≤0.1 dtex with one another and a back face layer are formed on either side of a first intermediate layer given by three-dimensionally entangling the ultrafine fibers with a fiber base cloth, and a front face layer having no entanglement of the fibers is formed on an outer surface of the second intermediate layer, wherein the leather has a number of the constituent ultrafine fibers of ≥3000 threads/mm<SP>2</SP>, the four layers each have a polymeric elastomer, adhesion between the fibers due to the elastomer does not exist in the front face layer, and the adhesion between the fibers due to the elastomer exists in three layers other than the front face layer. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a nubuck-like artificial leather.

There are two types of leather: smooth leather (silver surface, glass-clad leather) and brushed leather (suede, nubuck, velor, buckskin). Among these, nubuck is buffed and buffed leather. Is short and velvety, and is a raised leather that is denser than suede.
Various proposals have been made for suede-like artificial leather with long fluff and nubuck-like artificial leather with extremely short fluff. There are active proposals for nubuck-like artificial leather.
For example, the number of ultrafine fiber bundles having a fineness of 0.2 dtex or less is 400 to 3000 fibers / cm ² , and the relationship between the napped fiber bundle length X and the width Y is 0.3 ≦ X / Y ≦ 8.0. A nubuck-like artificial leather having a relatively short nap length (see Patent Document 1) has been proposed. These are composed of entangled bodies of ultrafine fiber bundles, which have a high flocking density, but are not entangled with ultrafine fibers, do not have short fluff structures, and are densely entangled with the superfine fibers of the present invention in three dimensions. This is different from the structure of nubuck-like artificial leather that produces short fluff.
Further, a dense nubuck-like sheet-like material having a surface composed of a three-dimensional entangled nonwoven fabric composed of ultrafine fibers and / or ultrafine fiber bundles and a dense foam existing in the entangled space, and a method for producing the same are known. (For example, refer to Patent Document 2). These use composite fibers and express short fluff with small fineness, but the dense surface is composed of a polymer elastic body impregnated in large quantities, and the nubuck-like artificial fibers composed of the ultrafine fibers of the present invention It is different from the leather structure.

Japanese Patent No. 3361976 Japanese Patent No. 3055849

  Recently, as a result of research and development by a patent applicant company, it has become possible to industrially produce ultra-fine fibers of 0.05 dtex. In addition, the three-dimensional entangled body using these ultra-fine fibers is not only densified compared to the conventional suede-like artificial leather, but also related to the increase in the number of constituent fibers and the increase in the fiber entanglement points. It has been found that even with the same raising treatment, the expressed fluff becomes shorter. That is, the present invention succeeded in producing a nubuck-like artificial leather having a dense feeling and short fluff, which is not found in conventional suede-like artificial leather.

  The present invention seeks to provide a nubuck-like artificial leather having a shorter fluff and a denser feeling than conventional suede-like artificial leather.

The present invention provides a second intermediate layer in which the ultrafine fibers are three-dimensionally entangled via a first intermediate layer formed by three-dimensionally entanglement of ultrafine fibers having a fineness of 0.1 dtex or less, and a back surface, And a total of 4 layers of the outer surface of the second intermediate layer of each of the above-mentioned layers without fiber entanglement, and the number of super fine fibers is 3000 / mm ² or more, and all four layers are made of a polymer elastic body The surface layer has no inter-fiber adhesion by an elastic body, and the other three layers except the surface layer are in nubuck-like artificial leather having fiber adhesion by an elastic body.

  The nubuck-like artificial leather of the present invention is a nubuck-like artificial leather that has a shorter fluff, a denser feeling, and is rich in luxury suitable for clothing than conventional suede-like artificial leather.

[Four-layer structure]
The nubuck-like artificial leather of the present invention has a second intermediate layer and a back layer in which the ultrafine fibers are three-dimensionally entangled via a first intermediate layer formed by three-dimensionally intermingling the ultrafine fibers and the fiber base fabric. In addition, the outer surface of the second intermediate layer of each layer is composed of a total of four layers having no fiber entanglement.

[Fineness]
The nubuck-like artificial leather of the present invention is obtained by three-dimensionally entanglement of ultrafine fibers and a fiber base fabric by the water jet method, and the ultrafine fibers used are uniform in fiber diameter and fiber length produced by the direct spinning method. What is excellent in is preferable. That is, a nubuck-like artificial leather excellent in appearance quality and denseness can be obtained by using a material excellent in uniformity of fiber diameter and fiber length.

  As described above, when three-dimensional entanglement is performed between the ultrafine fiber and the fiber base fabric, it is possible to obtain an artificial leather that is excellent in appearance quality and denseness by using a finer and shorter superfine. By making the fibers used thinner and shorter, the dispersion uniformity of the fibers can be dramatically improved, and an artificial leather with excellent appearance quality can be obtained. When compared with the same basis weight, the number of fibers increases when the ultrafine fibers used are made thinner and shorter. As a result, dispersibility is improved and denseness is improved. Further, as the fiber diameter becomes thinner, the fiber stiffness decreases, and as a result, the number of fiber entanglement points increases, the distance between the entanglement points decreases, and the entanglement strength increases.

The length of the fluff existing on the surface of the raised type artificial leather is the length from the fiber tip to the fiber entanglement point or the adhesion point, and when the distance between the fiber entanglement points is shortened, a short fluff is generated even when raising the hair. That is, the fineness of the ultrafine fibers used has a great influence on the surface density of the artificial leather to be formed and the length of the fluff.
The fineness of the ultrafine fiber used in the present invention is preferably 0.1 dtex or less. A fiber exceeding 0.1 dtex has a large diameter, a small number of fibers constituting the same basis, a small number of fiber entanglement points, a high density, and a desired nubuck-like texture having a short fluff and a high appearance quality. The lower limit of the fineness is not particularly limited, but is preferably 0.01 dtex from the viewpoint of obtaining a uniform fiber diameter and fiber length.

[Number of components]
The nubuck-like artificial leather of the present invention uses a three-dimensional entangled body in which ultra-fine fibers and a fiber base fabric are three-dimensionally entangled by the water jet method, but the formed sheet surface is homogeneous and dense. It depends on the amount used, its fineness and the cut length. Increasing the amount of ultrafine fibers used increases the number of fibers, but increases the weight and fabric thickness of the resulting artificial leather.

Artificial leather for clothing is preferred to be lightweight and thin-type, so artificial leather is often used with a thickness of 1 mm or less and a basis weight of 200 g / m ² or less. The nubuck-like artificial leather of the present invention has an increased number of constituents.
The nubuck-like artificial leather of the present invention comprises a three-dimensional entangled body of ultrafine fibers and a fiber base fabric and a polymer elastic body, and the content thereof is 40 to 60% by mass of the ultrafine fibers, 60 to 40% by mass of the fiber base fabric, The polymer elastic body is about 3 to 20% by mass. The amount of ultrafine fibers used in the present invention is substantially about 50 to 150 g / m ² .
In order to increase the number of components in the configuration basis weight of the ultra-fine fiber, it is possible to reduce the fineness and shorten the cut length.
In order to obtain the nubuck-like artificial leather of the present invention, it is necessary that the number of superfine fibers is 3000 / mm ² or more. When the number of constituents is less than 3000 / mm ^2, there is no difference with the texture of normal suede-like artificial leather.

The cut length of the ultrafine fiber used in the present invention is not particularly limited, but is related to the fineness, but is preferably in the range of about 1 to 4 mm. Further, if the cut length is shortened even when the fineness is 0.1 dtex or more, the above-mentioned number of constituents of 3000 / mm ² or more can be achieved. However, if the cut length is shortened when the fineness is 0.1 dtex or more, the fiber entanglement decreases and disappears. And lack of 3D confounding. For example, a nonwoven fabric having substantially strong fiber entanglement cannot be formed with a fineness of 0.1 dtex and a cut length of 2 mm. On the other hand, when the fineness is 0.1 dtex or less, the fiber rigidity is lowered and entanglement becomes possible, and a nonwoven fabric having substantially strong fiber entanglement is formed even with a cut length of 2 mm. When the fineness of the ultrafine fiber is 0.1 dtex or more, the bending rigidity is high and the interlace is difficult. Further, when the cut length is short, the confounding property is lowered.
In the present invention, the number of constituents is 3000 / mm ² or more by reducing the cut length of the ultrafine fiber to 2 mm or less, and further, by using the ultrafine fiber at 150 g / cm ² or less and the fineness to 0.1 dtex or less. Is realized.

[Fuzz length, surface fiber length]
The length of the fiber constituting the surface layer of the artificial leather in the present invention is mainly 200 μm or less. The fibers forming the surface layer of the present invention are fluff, which is the distance from the tip of the fiber to the entanglement point between the first fibers or the adhesion point between the fibers by the polymer elastic body, and the fluff is free on the sheet surface. The direction is changed.

[Base fabric]
As the fiber base fabric used in the present invention, woven fabrics, knitted fabrics, nonwoven fabrics and the like made of synthetic fibers such as acrylic fibers, nylon fibers, polyester fibers, polyethylene fibers, rayon, and semi-synthetic fibers can be used. The fiber base fabric used in the present invention is not limited as long as it can hold the fibers entangled with the base fabric, but it is preferable to use a high shrinkage knitted fabric made of polyester fibers that shrinks by heat treatment.

[Acrylic polymer]
The ultrafine fiber used in the present invention is not particularly limited, but it is preferable to use an acrylonitrile-based copolymer containing 50% by mass or more of acrylonitrile.
Other vinyl monomers that can be copolymerized with acrylonitrile include (meth) methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, etc. Examples thereof include acrylates, halogen salts such as vinyl chloride, vinyl bromide and vinylidene chloride, maleic imide, phenylmaleimide, (meth) acrylamide, styrene, α-methylsulfone, vinyl acetate and the like. Of these, methyl acrylate and vinyl acetate are preferred from the viewpoint of improving the spinnability of ultrafine acrylic fibers.
The specific viscosity of the acrylonitrile-based copolymer that forms the ultrafine acrylic fiber used in the present invention is preferably in the range of 0.05 to 0.5, which can ensure spin drawability from the copolymer, and more preferably Is in the range of 0.1 to 0.25.

[Polymer elastic body]
Examples of the polymer elastic body used in the nubuck-like artificial leather of the present invention include polyurethane elastic bodies, acrylonitrile-butadiene copolymers, styrene-butadiene copolymers, synthetic rubbers such as polybutadiene and neoprene, and polymers such as polyacrylates. There is an elastic body.
Among them, the polyurethane elastic body is excellent in flexibility and wear resistance and is suitable for artificial leather. Examples of the polyol component of the polyurethane elastic body include polyethylene diols such as polyethylene adipate glycol, polyether glycols such as polyethylene glycol and polypropylene glycol, and polycarbonate diols. As the isocyanate component, aromatic isocyanate, alicyclic isocyanate, and aliphatic diisocyanate can be used. Moreover, glycols, such as ethylene glycol, and diamines, such as ethylenediamine, can be used as a chain extender.

  Furthermore, the polyurethane elastic body is preferably a water-dispersed polyurethane elastic body obtained by the forced emulsion polymerization method from the above-described polyol component, diisocyanate component, and chain extender. As the water-dispersed polyurethane elastic body, a polyether-based non-yellowing polyurethane elastic body, a carbonate-based non-yellowing polyurethane elastic body, or a polyester-based elastic body can be used. Furthermore, it is preferable to use an antioxidant and a light stabilizer as a heat resistance improver in combination with the water-dispersed elastic body. Antioxidants include hindered amines, hindered phenols, and hydrazines.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.
The physical property values, texture, and fluff length used in Examples and Comparative Examples were measured, evaluated, and determined by the following means.
[Cloth thickness measurement]
A contact-type membrane pressure gauge manufactured by Peacok was used.
[Unit weight measurement]
Mass per unit area was measured and converted to basis weight (g / m ² ).
[Density measurement]
Density (g / cm ³ ) = weight per unit area (g / cm ² ) / cloth thickness (mm) / 1000
[Length of fluff]
The length of the fluff was determined by SEM observation of the sheet cross section in the raised state and the sheet cross section in the fluffed state.
[Acrylic fiber content]
The sheet was dissolved and removed with dimethylacetamide, and the acrylic fiber content was determined from the ratio of acrylic fibers (dissolved) and polyethylene terephthalate fibers (residue).
[Number of components]
The number of constituent acrylic fibers in the sheet was determined from the acrylic fiber content in the sheet and the mass of one constituent fiber. The fineness was confirmed by the fiber diameter. The fiber content was determined by a dissolution method. The number of components is calculated as follows.
Mass of one fiber [g] = fineness [dtex] / 1000000 [mm] × cut length [mm]
Number of components [lines / mm ² ] = acryl fiber content [g / mm ² ] / mass of one fiber [g]
[Density and texture]
The fineness and texture were determined by visual inspection and touch.

[Example 1]
・ Ultra-fine fiber (production method)
An acrylonitrile copolymer having a molar ratio composition of acrylonitrile / methyl acrylate / methallyloxybenzene sodium sulfonate = 95.0 / 4.3 / 0.7 and a specific viscosity of 0.22 obtained by aqueous suspension polymerization is used. Then, it was dissolved in dimethylacetamide (DMAC) to prepare a spinning dope having a polymer concentration of 15% by mass. This spinning dope is discharged from a spinneret having a pore diameter of 20 μm and a pore number of 40000 into a coagulation bath composed of a DMAC aqueous solution having a temperature of 40 ° C. and a concentration of 30% by mass, washed in boiling water and stretched 4 times, and further an oil agent Then, secondary stretching was performed 1.5 times with a dry heat roller at 180 ° C. to obtain an ultrafine acrylic fiber tow having a single fiber fineness of 0.06 dtex.
-Papermaking sheet After the acrylic fiber tow having a single fiber fineness of 0.06 dtex (fiber diameter: 2.6 μm) is cut into 3 mm, 20% by mass of polyvinyl alcohol fiber is used as a binder with respect to the acrylic fiber, and wet papermaking. A papermaking web (sheet) having a basis weight of 20 g / m ² was prepared by the method.
When this papermaking sheet was calculated from the fineness and the cut length, the number of fiber components was 1111 fibers / mm ² .

・ Nonwoven fabric formation Knitted fabric of 50 g / m ² (tentium, single jersey) per unit area consisting of polyethylene terephthalate filaments of 72 dtex / 36 f with a heat shrinkage of 45% (boiling water) (shrinkage: both width and length are approximately 25%) The paper sheet of 20 g / m ² per unit area produced above is placed on the paper sheet, placed on an 80-mesh wire mesh, and a pressure of 5 Mpa using a nozzle having a hole diameter of 0.125 mm from the paper sheet side. A water jet treatment was performed to form a nonwoven fabric having a basis weight of 70 g / m ² .
Next, the obtained non-woven fabric was inverted, the paper sheet having a weight per unit area of 20 g / m ² was placed, and water jet treatment was performed at a pressure of 5 Mpa. Further, the above-mentioned basis weight 20 g / m ² papermaking sheet was placed, and the same treatment was repeated to form a nonwoven fabric having a basis weight of 110 g / m ² . Next, the produced nonwoven fabric was treated in boiling water for 2 minutes and then dried. The nonwoven fabric shrunk by 25%. The basis weight of the obtained nonwoven fabric was 196 g / m ² . This nonwoven fabric was 54.5% by mass of acrylic fibers and 45.5% by mass of polyester fibers (base fabric). The content of acrylic fibers in this nonwoven fabric was 107 g / m ² , and the number of ultrafine fibers constituting this nonwoven fabric was about 5900 fibers / mm ² .
-Dyeing Next, the above-mentioned nonwoven fabric is dyed with a blue cationic dye (Nicilon Blue AQN: manufactured by Nissei Kasei Co., Ltd., f value = 0.21, dye adhesion amount 2.6%) using a high-pressure liquid flow dyeing machine (Uniace made by Nippon Dyeing Machine) Stained.

-Polymer elastic body impregnation treatment A water-based polyurethane (trade name: Inplanil DLN (manufactured by Bayer)) prepared to a solid content concentration of 5% was impregnated into a nonwoven fabric dyed by the above means and subjected to a drawing treatment. A 3% by weight aqueous solution of sodium alginate was applied to the surface via a # 100 screen, dried at 130 ° C. for 3 minutes, and then cured at 150 ° C. for 1 minute. The adhesion amount of polyurethane was 5% by mass.
-Surface grinding process Next, the surface of the nonwoven fabric prepared above was ground with sanding paper (# 240) to finish the appearance of the raised surface.
The artificial leather obtained by the above-mentioned means had a basis weight of 165 g / m ² , a fabric thickness of 0.45 mm, and a density of 0.37 g / cm ³ .
-Surface morphology and texture Fig. 1 shows a surface SEM image of the artificial leather, and Fig. 2 shows a cross-sectional SEM image.
The artificial leather surface was dense and had a nubuck tone composed of short napping. From the SEM image, it was observed that the length of raised hair was mainly composed of 200 μm or less.

[Comparative Example 1]
-Ultrafine fiber-Cut-Papermaking In the same manner as in Example 1, except that the diameter of the die hole and the draw ratio were changed, an acrylic fiber having a single fiber fineness of 0.13 dtex (fiber diameter: 3.8 µm) was obtained and cut into 3 mm Then, a papermaking web (sheet) having a basis weight of 20 g / m ² was prepared by a wet papermaking method.
As a binder, 20% by weight of polyvinyl alcohol fiber was used. The molar ratio composition of the acrylic fiber polymer was acrylonitrile / methyl acrylate / methallyloxybenzene sodium sulfonate = 95 / 4.3 / 0.7.
The number of fiber components calculated from the fineness and cut length of this papermaking sheet is 513 / mm ² .

・ Nonwoven fabric formation The paper sheet having a basis weight of 20 g / m ² manufactured above was placed on a knitted fabric of a basis weight of 50 g / m ² (Tenji, single jersey) made of 75 dtex / 36 f polyethylene terephthalate filaments having heat shrinkability. Was placed on an 80-mesh wire mesh, and a high-pressure jet water flow treatment was performed from the paper sheet side using a nozzle having a hole diameter of 0.125 mm at a pressure of 5 Mpa. A nonwoven fabric having a basis weight of 70 g / m ² was formed.
Next, the obtained non-woven fabric was inverted, the paper sheet having a weight per unit area of 20 g / m ² was placed, and water jet treatment was performed at a pressure of 5 Mpa. Further, the above-mentioned basis weight 20 g / m ² papermaking sheet was placed, and the same treatment was repeated to form a nonwoven fabric having a basis weight of 110 g / m ² . Next, the produced nonwoven fabric was treated in boiling water for 2 minutes and then dried. The nonwoven fabric shrunk by 25%. The basis weight of the obtained nonwoven fabric was 196 g / m ² . The composition ratio of the nonwoven fabric was 54.5% by mass of acrylic fiber and 45.5% by mass of polyester fiber (base fabric). The content of acrylic fiber in this nonwoven fabric is 107 g / m ² , and the number of super fine fibers in this nonwoven fabric is about 2700 / mm ² .
Thereafter, the same procedure as in Example was performed, and artificial leather was obtained by dyeing, polymer elastic body impregnation treatment, and surface grinding treatment.
The form of the obtained artificial leather finally had a basis weight of 185 g / m ² , a fabric thickness of 0.60 mm, and a density of 0.31 g / cm ³ .
-Appearance and texture Fig. 3 shows a surface SEM image of the artificial leather obtained, and Fig. 4 shows a cross-sectional SEM image.
The surface of the artificial leather had a suede-like texture composed of relatively long nappings. From the SEM image, it was observed that the length of the raised hair was mainly composed of 200 μm or more.

2 is a surface SEM photograph of nubuck-like artificial leather obtained in Example 1. 2 is a cross-sectional SEM photograph of nubuck-like artificial leather obtained in Example 1. 3 is a surface SEM photograph of artificial leather obtained in Comparative Example 1. 3 is a cross-sectional SEM photograph of artificial leather obtained in Comparative Example 1.

Claims (3)

A second intermediate layer in which the ultrafine fibers are entangled three-dimensionally via a first intermediate layer formed by three-dimensionally entanglement of ultrafine fibers having a fineness of 0.1 dtex or less and a fiber base fabric; The outer surface of the second intermediate layer of each layer is composed of a total of 4 layers with no fiber entanglement, the number of superfine fibers is 3000 / mm ² or more, all the 4 layers have a polymer elastic body, A nubuck-like artificial leather, characterized in that the surface layer does not have interfiber adhesion by the elastic body, and the other three layers except the surface layer have fiber adhesion by the elastic body.   The length of the fiber which comprises a surface layer is 200 micrometers or less, The nubuck-like artificial leather of Claim 1 characterized by the above-mentioned. The nubuck-like artificial leather according to claim 1 or 2, wherein ultrafine fibers made of an acrylonitrile copolymer containing 50% by weight or more of acrylonitrile are used.