JPS6233885A - Production of artificial leather having improved surface smoothness - Google Patents

Abstract

PURPOSE:To obtain artificial leather having good feeling and improved surface smoothness, by removing slice on one side of short fiber interlaced material, immersing the material in a solution of a polyurethane elastic material and squeezing the material at a specific squeezing clearance and coagulating the polyurethane elastic material. CONSTITUTION:Short fibers of a short fiber interlaced material consisting of a thermoplastic fibers such as nylon, polyester, etc., are mutually fixed by the use of an aqueous solution of polyvinyl alcohol and slice on one side is removed by a slicing machine to give nonwoven fabric having improved smooth ness. Then, the material is immersed in a solution of polyurethane elastic mate rial in a water-miscible organic solvent, squeezed at a squeezing clearance to satisfy the condition shown by the formula tn-0.2+Tmm (tn is thickness of short fiber interlaced material after slicing; T is squeezing clearance), and immersed in a nonsolvent to coagulate the polyurethane elastic material as a fine porous material, the polyvinyl alcohol is dissolved and removed to give artificial leather useful as bags, shoes, clothes, etc., having improved feeling and good surface smoothness.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a method for manufacturing artificial leather with a smooth surface, and more specifically, to a method for producing artificial leather that is suitable for use in cotton, bags, clothing, cases, belts, etc. The present invention relates to a method for producing artificial leather with excellent surface smoothness.

(Prior art) Conventionally, as a method for producing artificial leather with a smooth surface, a short:, nm entangled body is produced by two-dorno kunching,
The tangled short fibers are impregnated and coated with an aqueous solution of polyvinyl alcohol, dried to fix the fibers 8a to each other, and then impregnated with a water-miscible organic solvent solution of polyurethane elastomer, which is a non-solvent of polyurethane disstomer mainly composed of water. After coagulating and drying to form a base material, this base material may be used as is or after the surface has been sanded to obtain a smooth surface, a water-miscible organic solvent solution of polyurethane elastomer to form a silver layer is coated, This was wet coagulated.

(Problems to be Solved by the Invention) In the case of the conventional method, the short leather layer, the locus layer and the grain layer are very different in density and hardness, and the leather is far from natural leather in terms of appearance and metal. However, if the paper was subjected to a sifting process, both the fibers and the polyurethane resin would be removed, which could not be said to be economical.

(Means for Solving the Problems) The method for producing artificial leather of the present invention includes impregnating a short fiber entanglement made of thermoplastic fibers with a polyvinyl alcohol aqueous solution,
After drying and fixing the short fibers to each other, they were removed using a single-sided lath slicing machine, and then the polyurethane elastomer was impregnated with a water-miscible organic solvent, tn-0,2≦Tw.
, (tn Short slang after Nisraisu, thickness of Rakutai, T:
The process consists of squeezing the polyurethane elastomer with a squeezing liquid clearance that satisfies the condition (squeezing liquid clearance), then immersing it in a non-solvent to coagulate the polyurethane elastomer as a microporous body, and then removing the polyvinyl alcohol by a high layer. It is something.

The configuration of the present invention will be explained in detail below.

The short fiber entangled body is obtained by needle punching single or a mixture of short fibers selected from the group consisting of 6 nylon:/, 6.6 nylon, and polyethylene terephthalate, and polyethylene terephthalate does not contain heat-shrinkable transverse fibers. It's okay to stay.

After polyvinyl alcohol is added to the polyurethane disstomer, its elution rate into the non-vehicle during the coagulation process, the degree of elution into the non-vehicle during the coagulation process, the adhesion between the fiber and the polyurethane elastomer, and the adhesion to the fiber.1. This time, the degree of saponification is 1, including the fixation of f & Yuwa mutually.
It is necessary to set conditions such as concentration, plasticizer, antifoaming agent, squeezing rate, and drying speed.

Slicing is easily accomplished by a slicing machine equipped with a conventional endless knife. In order to minimize the loss of strength of the nonwoven fabric, the slices need only achieve the desired smoothness and should avoid removing too much thickness.

The composition of the polyurethane nidistomer is not particularly limited, and any polyurethane nidistomer that is generally used for artificial leather can be used. However, it is desirable that the molecular weight of the polyurethane elastomer is as large as possible from the viewpoints of bending resistance, hydrolysis resistance, coagulation properties, etc.

This polyurethane disstomer contains pigments, if necessary.
Added are ultraviolet 1 ray absorbers, antioxidants, blood activators, softeners, plasticizers, antifoaming agents, cellulose, 14-value agents, antifoaming agents, leveling agents, etc. Dimethyl formamide is the most preferable adhesive.When a solution of a polyurethane elastomer in a water-miscible organic solvent is applied to the voids of a short, tangled body in which the fibers are fixed with polyvinyl alcohol, a water-miscible organic solvent solution is applied. After that, in order to fill the liquid and give it a constant invasion, the excess liquid is removed by passing it between a pair of drive rolls with a constant gap.At this time, the gap between the liquid and the coolant is filled with a short fiber entangled body in which the fibers are fixed with polyvinyl alcohol. If the thickness is 0.2 vm or more thinner than the thickness of If the liquid gap is T (■), then tn-0,
It is necessary to remove the excess liquid under the condition of 2≦T.

After squeezing under these conditions, it may be immediately immersed in a non-solvent to solidify it, or it may be further coated with a polyurethane elastomer solution to form a silver surface layer and then immersed in a non-solvent.

(Example) The present invention will be further explained by showing examples below, but the following examples are not intended to limit the present invention.

(Example 1) 6 nylon L5 denier, Shin Wainaga 51wm 70chi,
A short fiber entangled body (zoor/m') consisting of 6 nylon 3 denier fibers with a length of 38 m and 30% was impregnated with an aqueous solution of polyvinyl alcohol with a degree of polymerization of 550 and a degree of saponification of 96.5%. After squeezing the liquid so as to have the following properties, it was dried at 140°C to fix the fibers to each other. Next, in order to adjust the thickness, the fabric was passed between upper and lower driven heat rolls having a surface temperature of 155°C to obtain a nonwoven fabric with a thickness of L3. This was then sliced using a slicing machine to obtain a 1.1 m long nonwoven fabric with extremely smooth surfaces on one side. then 100
Timozieras 57 Kg/di, tensile strength 684 K4
/cj, failure: A polyurethane elastomer with an elongation of 518% at the time of analysis was impregnated with a 19.5% tidimethylformamide solution, and a pair of vertically driven rolls with a gap of 1.0 μm was passed between a pair of vertically driven rolls to remove excess liquid. The polyurethane disstomer was coagulated by passing it through and immediately immersing it in water at 20°C.

This material had extremely smooth surface and was excellent as a base material for artificial leather. When a 0.3-inch thick grain layer was provided on this base material, an artificial leather with extremely smooth surface and rich feeling was obtained.

(Example 2) 6 nylon L2 denier, fiber length 63 x 10 inches, 6.6
A short interlaced piece of nylon (160 f/m') consisting of 0.8 denier nylon and a fiber length of 38 m and 30 cm was impregnated with a 3% polyvinyl alcohol 5 cm aqueous solution with a degree of polymerization of 1750 and a degree of saponification of 9 s. After squeezing the liquid to a thickness of 160 mm, it was dried along a hot roll coated with polytetrafluoroethylene to obtain a nonwoven fabric with a thickness of L1, and one side was removed using a slicing machine to a thickness of 0.9+w+. I got a smooth texture.

Next, it was impregnated with the polyurethane disstomer solution used in Example 1, passed between vertically driven rolls having a roll gap of 0.85 mm, and coagulated in water at 20C.

Similar to Example 1, this material was also an extremely smooth substrate for artificial leather.

(Comparative Example 1) The tangled short fibers used in Example 1 were impregnated with a polyurethane elastomer solution without being sliced, and the squeezed liquid gap L2 was
Although the polyurethane elastomer was coagulated in water at 20° C. after squeezing in step (3), the smooth surface obtained in Example 1 was not achieved.

(Comparison row 2) When the single-sided smooth nonwoven fabric of 1.1 cm after slicing used in Example 1 was impregnated with the polyurethane disstomer solution also used in Example 1, the gap Q was ,
The artificial leather base material obtained by passing between 8 ■ nip rolls is not a sloppy material with a small amount of resin filling and lacks a sense of fulfillment.
Even when a grain layer was formed thereon to a thickness of 0.4 m, the smoothness was inferior to that of Example 1 due to the lack of smoothness of the nonwoven fabric layer.

Claims (1)

[Claims] A short fiber entangled body made of thermoplastic fibers is impregnated with an aqueous polyvinyl alcohol solution, dried to fix the short fibers to each other, one side is removed by a slicing machine, and then a water-miscible organic solvent solution of polyurethane elastomer is impregnated. , t_n-0.2≦Tmm (t_n: thickness of short fiber entangled body after slicing, T: squeezing liquid clearance), and then immersed in a non-solvent to form a polyurethane elastomer. A method for producing artificial leather, which comprises coagulating polyvinyl alcohol into a fine porous body, and then dissolving and removing polyvinyl alcohol.