JP3973783B2 - Leather-like sheet - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a leather-like sheet having a natural leather-like feel and texture, and further having the feel and texture for a long period of time.
[0002]
[Prior art]
Conventionally, as a leather-like sheet, a wet layer or a dry layer made of an elastic polymer is applied to the surface of the fibrous base layer, and a high modulus polyurethane resin, silicon modified resin, acrylic resin, or the like is further applied to the surface. Proposed. This is less tacky and has a touch similar to that of natural leather to some extent, but is still far from the feel and texture of natural leather. Further, as a leather-like sheet having a tactile sensation similar to that of natural leather, a method has been developed in which natural leather powder, collagen, gelatin and the like are dispersed in a resin liquid and this dispersion is applied to the surface of the leather-like sheet.
[0003]
[Problems to be solved by the invention]
The leather-like sheet obtained by such a method is close to the touch of natural leather, but the adhesion between the resin applied to the surface and the lower layer is insufficient, and it does not endure long-term use.
As a result of diligent research to eliminate the drawbacks of the above-mentioned conventional techniques, the present inventors have a natural leather-like feel and texture, and the resin applied to the surface is excellent in adhesion to the lower layer and has an excellent appearance. A leather-like sheet was found and the present invention was reached.
[0004]
[Means for Solving the Problems]
That is, the present invention provides a leather-like sheet comprising a fiber assembly impregnated with an elastic polymer and a resin coating layer formed on the surface thereof, and the resin constituting the resin coating layer has a 100% modulus. It is mainly composed of 10 to 150 kg / cm ² of a silicon-modified polyurethane resin, and the surface of the resin coating layer is provided with a polyamino acid polyurethane resin in a spot shape, and the spot adjacent to the spot It is a leather-like sheet having a minimum distance of 10 to 100 microns.
[0005]
The present invention is described in detail below.
First, as the fibers constituting the fiber aggregate that is the base layer of the present invention, ordinary fibers such as synthetic fibers made of fiber-forming polymers such as polyester, polyamide, polyacrylonitrile, polyolefin, polyvinyl alcohol, regenerated cellulose fibers, acetates are used. Examples thereof include chemical fibers such as fibers, and natural fibers such as cotton, hemp, and wool. In the case of a synthetic fiber, not only a fiber composed of a single polymer but also a fiber obtained by mixing or spinning two or more polymers may be used. When mixed-spun fibers or composite-spun fibers are used, at least one of the plurality of polymers constituting the fibers is extracted or removed at any stage of producing the leather-like sheet. It is preferable to adopt a method or a method of dividing the polymer component constituting the fiber into a fine fiber bundle or a porous fiber having a large number of hollow portions inside.
[0006]
These fibers are used as webs and entangled with a needle punch or high-speed fluid to form nonwoven fabrics. It can also be a knitted fabric. Furthermore, it can also be set as the laminated body of a nonwoven fabric and a knitted fabric. These nonwoven fabrics, woven and knitted fabrics, and laminated fabrics thereof (hereinafter collectively referred to as fiber aggregates) are impregnated with an elastic polymer liquid. Prior to the impregnation treatment with the elastic polymer liquid, the fiber aggregates may be used as necessary. The surface is smoothed by a method such as hot pressing. In addition, in order to prevent the shape failure of the fiber aggregate that is likely to occur during the subsequent impregnation / coagulation of the elastic polymer liquid or the extraction process of the fiber constituent polymer, the surface of the fiber aggregate is heated and pressed so that part of the constituent fibers are partially A method of fusing, or a method of impregnating a fiber assembly with a water-soluble resin typified by polyvinyl alcohol and gluing and fixing between fibers may be used. The thickness of the fiber assembly is preferably in the range of 1.0 to 3.0 mm.
[0007]
The elastic polymer impregnated in the fiber assembly of the present invention is at least one elastic member selected from the group of elastic polymers such as polyurethane, acrylonitrile / butadiene copolymer, styrene / butadiene copolymer, and natural rubber. A polymer can be mentioned. Polyurethane elastomers are particularly preferred from the viewpoints of texture and adhesive strength with the resin coating layer formed on the surface. As the polyurethane elastomer, a polymer diol having a number average molecular weight of 500 to 2500, for example, at least one polymer diol selected from polyester diol, polyether diol, polyester ether diol, polycaprolactone diol, polycarbonate diol, and the like, At least one organic polyisocyanate selected from the group of aromatic diisocyanates, alicyclic diisocyanates, aliphatic diisocyanates and the like, and low molecular compounds having at least two active hydrogen atoms, such as low molecular diols, low molecular diamines, hydrazines And a polyurethane elastomer obtained by reacting a low molecular weight compound containing active hydrogen atoms such as dicarboxylic acid dihydrazide as a chain extender.
[0008]
The raw material composition of these polyurethane elastomers can be appropriately selected from those satisfying various physical properties such as texture, deterioration resistance, yellowing resistance, and dyeability according to the application field directed to the leather-like sheet. If necessary, other polymers, various stabilizers, colorants, coagulation regulators, and the like are added to these elastic polymers. The elastic polymer is impregnated into the fiber assembly in the form of a solution or dispersion and solidified. As the coagulation method, a wet coagulation method is preferable in terms of texture. The amount of the elastic polymer impregnated into the fiber assembly is 10 to 60 parts by weight with respect to 100 parts by weight of the fiber assembly impregnated with the elastic polymer in terms of elastic polymer solid content.
[0009]
When the fiber assembly is composed of mixed spun fibers or composite spun fibers composed of two or more kinds of polymers, before or after impregnating the fiber assembly with the elastic resin, It is preferable to use a method in which at least one component is dissolved or decomposed to remove at least one component. For example, when the mixed spun fiber or the composite spun fiber is a fiber having a sea-island cross section, when the sea component polymer is dissolved or decomposed and removed, the island component polymer remains, and the fiber becomes an ultrafine fiber bundle, while the island component polymer is dissolved and removed. Then, the sea component remains and becomes a porous fiber having many hollow portions in the fiber. In addition, when the fiber is a composite spun fiber in which a plurality of polymers are bonded in the length direction, the fiber is separated from the polymer by a physical treatment or a chemical treatment to form a fiber bundle. May be used.
[0010]
After impregnating the fiber assembly with the elastic resin, a coating layer made of the elastic resin is formed on the surface thereof. As the elastic polymer used for the coating layer, polyurethane elastomer is most preferable in terms of obtaining adhesion to the fiber assembly layer and a natural leather-like texture. As the polyurethane elastomer constituting the coating layer, at least one kind of polymer diol, organic polyisocyanate, and active hydrogen atoms as described above are used in the same manner as the polyurethane elastomer suitably used for impregnation of the fiber assembly. Examples thereof include polyurethane elastomers obtained by reacting at least two low molecular compounds as chain extenders. The raw material composition of these polyurethane elastomers can be appropriately selected according to the application field to which the leather-like sheet is directed, like the polyurethane elastomer to be impregnated, but especially the texture, deterioration resistance, yellowing resistance, cost, etc. In this respect, a polyether-based polyurethane using a polyether diol as the polymer diol is preferable.
[0011]
In particular, as the polyurethane elastomer used in the coating layer, a silicone-modified polyurethane resin is preferable in that it provides abrasion resistance and a natural leather-like feel. Specifically, a dimethylsiloxane unit is introduced into the main chain or side chain of the polyurethane. This is a modified polyurethane. The degree of silicon modification is preferably 2 to 20% by weight of dimethylsiloxane units in the polyurethane.
In particular, a polyurethane having a 100% modulus of 10 to 150 kg / cm ² which is a silicon-modified polyurethane resin is very preferable for achieving the object of the present invention, that is, a natural leather-like feel. When the 100% modulus is less than 10 kg / cm ² , tackiness becomes very high and surface strength becomes weak. On the other hand, if the 100% modulus exceeds 150 kg / cm ² , the coating layer becomes too hard and the bending resistance is deteriorated. Preferably it is 20-100 kg / cm < ² >. The resin for forming the coating layer is used in the form of a solution or an emulsion. The method for forming the coating layer may be a method in which the coating layer is directly applied to the fiber assembly, or a resin solution for the coating layer is previously applied on the release sheet and solidified, and then the adhesive layer is used. A method may be used in which the resin liquid is applied thereon and is superposed and integrated with the fiber assembly, and then the release sheet is peeled off. As the resin used as an adhesive in this method, a two-component curable polyurethane is preferable in that a strong adhesive force can be obtained. As a method for solidifying the coating layer, a dry solidification method is used. Of course, various stabilizers, other resins, colorants and the like may be added to the resin for forming the coating layer. The 100% modulus is measured by the strength at the time of 100% elongation from the stress and elongation curve of the dry film produced from the resin liquid. The thickness of the coating layer is in the range of 30 to 150 μm.
[0012]
A polyamino acid polyurethane resin is applied to the surface of the coating layer in the form of spots in order to give a natural leather-like feel and texture. A polyamino acid polyurethane resin is a block copolymer in which a polyurethane unit and a polyamino acid unit are bonded in a block form. As a typical production method thereof, a terminal obtained by reacting a polymer diol with a diisocyanate compound first. It is obtained by reacting a prepolymer having an isocyanate group with an excess of a diamine compound to synthesize a polyurethane having an amino group at the terminal, and subjecting this to ring-opening addition polymerization of an amino acid-N-carbonic anhydride. Representative examples of the polymer diol include polyether diol, polyester diol, polycarbonate diol, and the like, typical examples of the diisocyanate compound include hexamethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, and the diamine compound includes ethylenediamine. And propylenediamine. Further, examples of the amino acid-N-carbonic acid anhydride include amino acids such as valine, noribaline, leucine, isoleucine, and methionine, and N-carbonic acid anhydrides such as γ-methylglutamic acid, β-methylaspartic acid, and γ-benzylglutamic acid. Either the optically active form or the racemic form may be used, and these may be a mixture. In the present invention, the preferred weight ratio of the polyurethane block to the polyamino acid block in the polyamino acid polyurethane is 10:90 to 90:10.
[0013]
The polyamino acid polyurethane resin needs to exist in the form of a spot, and does not exist in the form of a spot, for example when it exists as a continuous layer or when it exists as a layer that is continuous in one direction Has poor adhesion to the lower layer and poor flex resistance. The size of individual spots in the present ^{invention, 10 - 4 ~10 - 2 mm} 2 is preferred.
[0014]
The polyamino acid polyurethane resin may be applied by any of the known methods such as spraying, gravure printing, textile printing, and transfer, but the gravure printing method is preferred as a method for easily applying in a spot shape. In order to achieve both the tactile sensation and adhesiveness of natural leather, which is a feature of the present invention, it is necessary to maintain the shortest distance between a spot and a spot adjacent thereto between 10 and 100 microns. When the shortest distance is less than 10 microns, the adhesion with the lower layer is deteriorated. On the other hand, if it exceeds 100 microns, the adhesiveness is good, but the feel of natural leather cannot be obtained. A suitable coating amount of the polyamino acid polyurethane resin is in the range of 0.2 to 5 g / m ^{2 in} terms of resin solid content.
[0015]
In the present invention, a colorant may be added to the above-described coating layer and the polyamino acid polyurethane resin present in the form of spots on the surface thereof, and a pigment or a dye is used as the colorant to be added. As the pigment carbon black, inorganic pigments such as titanium oxide, phthaloyl cyanine, azo, and organic pigments anthraquinone etc. are used. As the dye, a metal-containing complex dye, an acid dye, a sulfur dye, a disperse dye, and the like are used, and a metal-containing complex dye is preferable in terms of light resistance and fastness. The addition amount is preferably 1 to 30 parts by weight with respect to 100 parts by weight of the resin.
[0016]
The leather-like sheet having the surface of the polyamino acid polyurethane resin existing on the surface by the above method can be subjected to an embossing treatment, a scouring treatment, a dyeing treatment, or the like, if necessary.
[0017]
The leather-like sheet obtained in the present invention is a leather-like sheet having the feel of natural leather, having a very good texture, and excellent adhesion between the resin applied to the surface and the lower layer. These leather-like sheets are very suitable for applications such as clothing, bags, bags, gloves and general shoes.
[0018]
【Example】
Next, the content of the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples. In the examples, “part” and “%” relate to weight unless otherwise specified.
[0019]
Example 1
6-Nylon 60 parts (island component) and high-fluidity low-density polyethylene (sea component) 40 parts sea-island composite fiber was obtained by melt spinning, and this was stretched 2.5 times in 70 ° C warm water, A fiber oil agent was applied, mechanical crimped and dried, then cut to 51 mm to obtain 3 denier staple fibers. The staple fiber is formed into a web having a basis weight of 500 g / m ² by the cross wrap method, and then alternately punched from both sides to perform needle punching of about 500 punch / cm ² , further heated to 120 ° C., and pressed with a calender roll. Thus, an intertwined nonwoven fabric having a smooth surface was produced. The basis weight of this entangled nonwoven fabric was 340 g / m ² and the apparent specific gravity was 0.3. This entangled nonwoven fabric is impregnated with a 13% concentration polyurethane dimethylformamide (DMF) solution mainly composed of polytetramethylene ether polyurethane and dipped in a DMF / water = 15/85 mixed solution to wet-solidify the polyurethane. Then, the sea component (polyethylene) in the staple fiber was eluted and removed in hot toluene to make the staple fiber into an ultrafine fiber bundle to obtain a fibrous base layer. The resulting fibrous base layer had a thickness of 1.0 mm and the amount of polyurethane was 120 g / m ² .
[0020]
On the other hand, on a release paper with grain (Lintec TP R-8), 100 parts of silicon-modified polyether polyurethane (Seiko Kasei US-938, 100% modulus 60%, solid content 30%) as a coating layer, titanium oxide DUT4093 (large NISSEI Kogyo Co.) 30 parts, DMF30 parts, the polyurethane resin solution consisting of 30 parts of methyl ethyl ketone was coated so as to become a thickness of 50 microns on a dry basis, and dried for 5 minutes at 100 ° C., the coating layer Got. On top of this, a two-component curable polyether-based polyurethane solution is applied on a dry base so as to have a thickness of 30 microns, dried at 50 ° C. for 3 minutes, and the above-mentioned fibrous material is still sticky. It was bonded to the substrate layer, dried at 100 ° C. for 2 minutes, and then allowed to stand at 40 ° C. for 3 days, after which the release paper was peeled off to obtain a leather-like sheet (A). On the surface, a polyamino acid urethane resin solution [Lack Skin A-3571 (manufactured by Seiko Kasei Co., Ltd., block copolymer of polyamino acid and polycarbonate polyurethane: solid content concentration: 10%)] is a 200 mesh lattice gravure roll (200 lines). / 1 inch, cell depth of 30 microns) and applied in an amount of 1 g / m ² . The distance between spots was 30 microns. Furthermore, a stagnation process was performed to give flexibility. The obtained leather-like sheet had the feel of natural leather, had good adhesion between the leather-like sheet (A) and the surface spot, and had a soft texture. This leather-like sheet can withstand long-term use because of the good adhesion of the surface spots, and was optimal as an original fabric for gloves.
[0021]
Example 2
An intertwined nonwoven fabric of multicomponent fibers was prepared using 50 parts of 6-nylon kneaded with black pigment as a dispersion component and 50 parts of polyethylene as a dispersion medium component. This nonwoven fabric had a basis weight of 450 g / m ² and an apparent specific gravity of 0.26. The nonwoven fabric was impregnated with a 18% dimethylformamide (DMF) solution of polyethylene adipate / polyethylene glycol copolymer polyurethane containing a black colorant, and the same kind of solution was knife-coated on the surface in an amount of 80 g / m ^2. After solidifying in a% DMF aqueous solution, the polyethylene in the multicomponent fiber was dissolved and removed to obtain a fibrous base layer. The obtained fibrous base layer had a basis weight of 500 g / m ² , a thickness of 1.3 mm, and a resin impregnation amount of 120 g / m ² .
[0022]
The surface layer was treated with polycarbonate-based polyurethane [Rezamin M6701 (solid content concentration: 15%, manufactured by Dainichi Seika Co., Ltd.), four stages of 150 mesh with a gravure, and the coating amount was 60 g / m ² with a resin solution. On top of that, embossing was performed using a pore embossing embossing roll under conditions of a temperature of 150 ° C., a press pressure of 2 kg / cm ² , and a speed of 2 m / min. Next, gravure treatment was performed on the print roll using a polyamino acid polyurethane resin (Lackskin U-3295A, manufactured by Seiko Kasei Co., Ltd., non-yellowing type urethane: solid content concentration 13%). The size of each spot resulting 4 × 10 ^- a ³ mm ^2, the distance between the spots Atsuta at 50 microns. Thereafter, an embossing treatment was performed using a hair embossing roll under conditions of a temperature of 150 ° C., a pressure of 3 kg / cm, and a speed of 2 m / min. In addition, a blush treatment was applied to improve the texture.
The obtained leather-like sheet was excellent in antifouling property, and the surface spot and the lower-layer leather-like sheet had good adhesion and texture. However, compared with the leather-like sheet of Example 1, the coating layer was not a silicon-modified polyurethane, so that it was slightly inferior to that of Example 1 in terms of tack (feel).
[0023]
Comparative Example 1
In Example 1, a leather-like sheet was obtained in the same manner as in Example 1 except that the surface was not provided with a polyamino acid polyurethane resin. When this material was used as a raw material for men's shoes, it was quite different from the feel of natural leather, had a poor texture, and was inferior in commercial value.
[0024]
Comparative Example 2
In Example 1, the polyamino acid polyurethane resin was not applied in a spot shape, but was applied to the entire surface using a direct roll at a solid content of 20 g / m ² . The obtained leather-like sheet was close to the feel of natural leather, but the adhesion between the surface layer and the lower layer was poor and the texture was hard, and the product value was lower than that of Example 1. It was.
[0025]
【The invention's effect】
The leather-like sheet obtained in the present invention has the feel of natural leather, the texture is very good, and the adhesion between the lower layer and the surface spot is excellent. The leather-like sheet of the present invention is very suitable for uses such as clothing, bags, bags, gloves, and general shoes.

Claims (1)

A leather-like sheet comprising a fiber assembly impregnated with an elastic polymer and a resin coating layer formed on the surface thereof, wherein the resin constituting the resin coating layer has a 100% modulus of 10 to 150 kg / cm ² is mainly composed of a silicone-modified polyurethane resin, and the surface of the resin coating layer is provided with a polyamino acid polyurethane resin in a spot shape, and the shortest distance between the spot and the adjacent spot is Leather-like sheet that is 10-100 microns.