JP2002317386A - Method for producing leathery sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an eco-friendly method for producing a leathery sheet having good durability and flexibility without using organic solvent. SOLUTION: The method for producing a leatherly sheet comprises (1) a step to produce a sheet with fibers for producing ultrafine fibers and composed of a combination of two or more kinds of polymers having different solubility in alkaline aqueous solution, (2) a step to apply a polymer A to the sheet, (3) a step to apply a polymer B by impregnating an aqueous dispersion of the polymer B to the sheet and (4) a step to develop the ultrafine fibers by treating the sheet with an alkaline aqueous solution. The steps are performed in the order described above or reversing the order of the steps 2 and 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a leather-like sheet having both durability and flexibility and being environmentally friendly. More specifically, the present invention relates to a method for producing a soft leather-like sheet having excellent abrasion resistance, strength, and texture.

[0002]

2. Description of the Related Art A leather-like sheet obtained by providing a polymer sheet with a polymer elastic body is widely used in clothing, furniture and the like. In particular, leather-like sheet materials using ultrafine fibers of 0.3 dtex or less have a texture and touch similar to natural leather, and their use has been expanding in recent years.

However, there is a concern that the use of an organic solvent may adversely affect the environment, and it has been desired to produce a leather-like sheet without using an organic solvent. A method using an alkaline aqueous solution without using an organic solvent in the ultrafine fiber development treatment is disclosed in, for example, JP-A-6-316814. But,
In the method disclosed in the above-mentioned publication, a water-soluble reinforcing agent usable in an organic solvent could not be added, and only a material having a poor texture and quality could be obtained as compared with a method using an organic solvent for the ultrafine fiber development treatment.

[0004] Further, leather-like sheet materials are required to have a higher level of durability. To simply increase the abrasion resistance, it is sufficient to apply a large amount of polymer elastic body, but if it is applied too much, the texture will be reduced and the flexibility and quality that are the inherent characteristics of the product will be lost. I will. In addition, a method of obtaining a highly durable leather-like sheet by modifying an elastic polymer has been studied, but a method that satisfies flexibility and durability has not yet been obtained.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide an environment-friendly method for producing a leather-like sheet which has both durability and flexibility and does not use an organic solvent.

[0006]

The present invention has the following arrangement to solve the above-mentioned problems.

That is, the present invention relates to a method for producing a leather-like sheet. A step of producing a sheet using an ultrafine fiber-expressing fiber sheet composed of two or more polymer substances having different solubility in an alkaline aqueous solution. 2. A step of applying a polymer A satisfying all the following characteristics (1) to (3) to the sheet. (1) The weight loss rate after immersion in a 10% by weight aqueous sodium hydroxide solution at 40 ° C. for 20 minutes is 10% or less. (2) The weight loss after immersion in N, N-dimethylformamide for 60 minutes is 5% or less. (3) The weight loss rate after immersion in hot water of 98 ° C. for 30 minutes is 95% or more. 3. A step of impregnating the sheet with an aqueous dispersion of the polymer B that satisfies all of the following properties (1) to (3) to give the polymer B: (1) 100% elongation modulus after immersion in a 1.0% by weight aqueous sodium hydroxide solution at 90 ° C. for 30 minutes is 10
~80kg / cm ^2. (2) The weight swelling ratio after immersion in N, N-dimethylformamide for 30 minutes is 300% or less. (3) Breaking strength after immersion in hot water of 98 ° C. for 30 minutes is 100 kg / cm ² or more. 4. A step of treating the sheet with an aqueous alkaline solution to develop ultrafine fibers. Are performed in this order or in the order in which 2 and 3 are interchanged.

[0008] Alternatively, a method for producing a leather-like sheet material, comprising: A step of preparing a sheet using ultrafine fiber-expressing fibers composed of a combination of two or more polymer substances having different solubility in an aqueous alkali solution. 2. A step of applying a polymer A satisfying all the following characteristics (1) to (3) to the sheet. (1) The weight loss rate after immersion in a 10% by weight aqueous sodium hydroxide solution at 40 ° C. for 20 minutes is 10% or less. (2) The weight loss after immersion in N, N-dimethylformamide for 60 minutes is 5% or less. (3) The weight loss rate after immersion in hot water of 98 ° C. for 30 minutes is 95% or more. 3. A step of impregnating the sheet with an aqueous dispersion of the polymer B that satisfies all of the following properties (1) to (3) to give the polymer B: (1) 100% elongation modulus after immersion in a 1.0% by weight aqueous sodium hydroxide solution at 90 ° C. for 30 minutes is 10
~80kg / cm ^2. (2) The weight swelling ratio after immersion in N, N-dimethylformamide for 30 minutes is 300% or less. (3) Breaking strength after immersion in hot water of 98 ° C. for 30 minutes is 100 kg / cm ² or more. 4. A step of treating the sheet with an aqueous alkaline solution to develop ultrafine fibers. 5. A step of impregnating and applying a polyurethane solution to the sheet. Are performed in this order.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the method for producing a leather-like sheet according to the present invention, first, a sheet is produced by using an ultrafine fiber-expressing fiber composed of a combination of two or more polymer substances having different solubility in an aqueous alkali solution. Is necessary.

In the present invention, a polymer substance having a different solubility in an aqueous alkaline solution means that the dissolution rate is at least 20 times, more preferably 40 times or more, under the conditions for developing ultrafine fibers.
It means that it is more than twice different. When the ratio is less than 20 times, it is difficult to control the fineness of the polymer material having low solubility when developing the ultrafine fibers, which is not preferable.

In the present invention, high-molecular substances having high solubility in an aqueous alkali solution are not particularly limited. However, from the viewpoint of alkali dissolution rate and spinning stability, polyesters such as polyethylene terephthalate and polybutylene terephthalate can be added to 5-sodium sulfoisophthalate. Acid, polyethylene glycol, sodium dodecylbenzenesulfonate, bisphenol A compound, isophthalic acid, adipic acid, dodecadionic acid, cyclohexylcarboxylic acid, etc.
Copolymerized polyesters copolymerized at １２12 mol% are preferred. Particularly, from the viewpoint of heat resistance and weak alkali solubility, it is more preferable to use a polyethylene terephthalate copolymer obtained by copolymerizing 5 to 12 mol% of 5-sodium sulfoisophthalic acid. In addition, these copolymers are not only binary but also three-component.
It may be a multi-component copolymer or higher.

In the present invention, as the polymer having low solubility in an aqueous alkali solution, polyesters such as polyethylene terephthalate, polypropylene terephthalate and polybutylene terephthalate, and polyamides such as nylon-6 and nylon-6,6 are preferably used. it can.

The present invention is characterized in that ultrafine fibers are expressed using an alkaline aqueous solution, but the alkaline aqueous solution is not particularly limited, and may be an aqueous sodium hydroxide solution, an aqueous potassium hydroxide solution, an ammonium salt, or the like. Can be preferably used. In addition, it is preferable to perform the treatment while appropriately applying heat and to perform the treatment by adding a penetrating agent such as a surfactant in order to enhance the treatment efficiency.

The form of the ultrafine fiber-expressing fiber used in the method for producing a leather-like sheet according to the present invention is, for example, a polymer inter-arrayed fiber as disclosed in JP-B-48-22126 or the like. No. 51-21041, Japanese Patent Publication No. 60-21904, etc.
It is preferable to appropriately select and use the splittable conjugate fiber or the like shown in JP-A-9-310230 according to the purpose. The fineness of the ultrafine fibers obtained from such fibers is 0.3
dtex or less is preferred in terms of texture such as flexibility, but it is not necessary that all the single fibers contained in the nonwoven fabric be 0.3 dtex or less. What is necessary is just to become the state comprised by the fiber.

In the method for producing a leather-like sheet according to the present invention, when forming a sheet using such ultrafine fiber-expressing fibers, the form thereof is not particularly limited, and may be a woven fabric, a knitted fabric, a nonwoven fabric or a nonwoven fabric. A composite or the like thereof can be preferably used, but a nonwoven fabric is more preferable in terms of flexibility and texture. Such a nonwoven fabric is not particularly limited, and any of a short fiber nonwoven fabric and a long fiber nonwoven fabric can be used. In addition, non-woven fabric manufacturing methods are also spunbond method, melt blow method, flash spinning method,
Any of a paper making method and a card method may be used, and if necessary, the entanglement may be performed by a needle punch method, a water entanglement method or the like.

In the present invention, a polymer A and a polymer are used as a reinforcing agent for reinforcing the shape retention of the sheet prepared using the above-mentioned ultrafine fiber-expressing fibers, such as thickness and length, during the ultrafine fiber expression treatment. B is given.

The polymer A has the following characteristics. (1) The weight loss after immersion in a 10% by weight aqueous sodium hydroxide solution at 40 ° C. for 20 minutes is 10% or less. (2) The weight loss after immersion in N, N-dimethylformamide for 60 minutes is 5% or less. (3) The weight loss rate after immersion in hot water of 98 ° C. for 30 minutes is 95% or more. It is necessary to satisfy all the characteristics.

The weight reduction rate of (1) is preferably 10% or less, more preferably 3% or less, in view of the form and function retention during the process of developing ultrafine fibers. In addition, the weight reduction rate of (2) is preferably 3% or less from the viewpoint of easy control of the applied amount when the specific polyurethane is applied. Further, the weight reduction rate of (3) is preferably 97% or more for removing the above-mentioned polymer A with hot water for the purpose of adjusting the quality and texture, and more preferably 100%.
Is more preferable.

By having such properties, it is possible to maintain the felt form and function at the time of the ultrafine fiber development treatment, and furthermore, it is possible to control the adhesiveness to the polymer B and polyurethane, so that the quality of the leather-like sheet is improved. , Texture and physical properties can be arbitrarily controlled according to the purpose. As the polymer A, polyvinyl alcohol or a derivative thereof, water-soluble starch, carboxymethyl cellulose, partially saponified acrylate, polyacrylamide, cellulose acetate, and the like can be used. In the present invention, the degree of saponification is particularly 90%. The above polyvinyl alcohols are preferred in terms of handling, and more preferably polyvinyl alcohol having a saponification degree of 95% or more.

Further, in order to reduce the solubility in an aqueous alkali solution, it is preferable to apply a heat treatment after applying the polymer A to a sheet prepared using ultrafine fiber-expressing fibers, since it is extremely effective. The temperature of this heat treatment is 13
The temperature is preferably from 0 ° C to 195 ° C. From the viewpoint of easy control in the removal treatment of the polymer A, it is more preferable that the temperature is 140 ° C or higher and 180 ° C or lower. If the temperature is lower than 130 ° C., the polymer A may partially dissolve in an alkaline aqueous solution, and if it is higher than 195 ° C., the polymer A may be insolubilized and may not be removed. . The heat treatment time can be appropriately determined according to the situation and purpose, depending on the form of the sheet and the performance of the heat treatment apparatus. For the same purpose, a generally known solubilizing agent for the aqueous solution of the polymer A such as boric acid or borax may be added.

In the present invention, the polymer B is further applied using a dispersion obtained by dispersing the polymer B in water. The polymer B may be applied before applying the polymer A to the sheet. That is, in the step of applying the polymers A and B, the order of the steps may be A followed by B, or vice versa.

The polymer B has the following properties: (1) a 100% elongation modulus after immersion in a 1.0% by weight aqueous sodium hydroxide solution at 90 ° C. for 30 minutes;
~80kg / cm ^2. (2) The weight swelling ratio after immersion in N, N-dimethylformamide for 30 minutes is 300% or less. (3) Breaking strength after immersion in hot water of 98 ° C. for 30 minutes is 100 kg / cm ² or more. It is necessary to satisfy all the characteristics.

The 100% elongation modulus of (1) is 10 to 80 kg in terms of the form and the function retention of the leather sheet.
/ Cm ² . In addition, the weight swelling ratio of (2) is an index that the polymer B does not easily fall off due to the solvent of the polyurethane when a polyurethane soluble in DMF is provided, as described later. The content is 300% or less for controlling the amount of the molecule B applied. Further, the breaking strength of (3) needs to be 100 kg / cm ² or more from the viewpoint of heat resistance, and preferably 300 kg / cm ² or more.

As long as the polymer material satisfies this property, the polymer B is not particularly limited. For example, polyurethane, a polyamino acid polyurethane copolymer, an acrylate polymer, or the like can be used. Polyurethane is particularly preferred in terms of softening the texture. As a kind of such a polyurethane, for example, a polyether-based, polyester-based, or polycarbonate-based polyurethane can be preferably used. From the viewpoint of maintaining the form and function during the ultrafine fiber development treatment, it is preferable to have hydrolysis resistance to alkali, and polyether polyurethane or polycarbonate polyurethane is preferable.

A more preferred method of the present invention comprises:
In the method for producing a leather-like sheet of the present invention described above,
The leather-like sheet produced has a fineness of 0.3 dte.
x, ultrafine fibers, polyurethane which is soluble in N, N'-dimethylformamide, and polyurethane which is insoluble in N, N'-dimethylformamide.

In the production method of the present invention, the sheet is impregnated with an aqueous dispersion of the polymer B and then dried to remove water. In this case, a so-called migration phenomenon in which the polymer B migrates to both the front and back surfaces of the sheet may occur. In this case, if necessary, a method of breaking the emulsion before drying by steam treatment, a method of uniformly removing moisture from the inner and outer layers of the substrate by microwave heating, a method of wet coagulation in a salt water bath, a thickener It is also possible to adjust the degree of migration by a method of adding a migration inhibitor such as a thermosensitive gelling agent or the like.

[0027] In the present invention, a solvent to be removed when the ultrafine fiber expression treatment is performed by removing a polymer substance having high solubility in an aqueous alkali solution contained in the fibers constituting the sheet provided with the polymer A and the polymer B. As, it is necessary to use an alkaline aqueous solution, in which case heating, stirring,
It is preferable to perform operations such as squeezing liquid. At this time, a polymer material having lower solubility may be partially dissolved, but it is necessary to carry out the treatment under the condition that the shape and function of the sheet are substantially maintained during the treatment.

In the present invention, after the ultrafine fibers are developed, the sheet is impregnated with a polyurethane solvent and applied. As a solvent for such a polyurethane, dimethylformamide, methyl ethyl ketone, toluene, isopropyl alcohol, ethyl acetate, methylene glycol monoethyl ether and the like can be preferably used.

It is preferable that the total amount of the polyurethane to be applied is appropriately determined according to the shape of the sheet or the type and amount of the elastic polymer previously applied from the aqueous dispersion. It is preferable to provide it so that

In the present invention, a solution of polyurethane soluble in DMF is applied to a sheet, coagulated, immersed in warm water to remove a reinforcing agent, and then sliced and buffed as necessary by a conventional method. Or a substrate for suede. This substrate can be subjected to appropriate post-processing.

[0031]

The present invention will be described below with reference to examples. Parts in Examples refer to parts by weight. The dissolution rate and weight reduction rate in the present invention were measured by the following methods. (1) Dissolution rate The dissolution rate was determined from the weight ratio obtained by setting the treatment time to 1 hour according to the chemical resistance test according to JIS K6911. (2) Weight reduction rate (a) W ₀ g was obtained by impregnating polymer A with 2 g of polypropylene non-woven fabric so that the total weight was approximately 5 g, and this was W ₀ g. 2 in 300 mL of a 10% by weight aqueous sodium hydroxide solution kept at
The weight after immersion for 0 minutes was determined as W ₁ g by the following equation.

Weight loss rate = (W ₀ −W ₁ ) / (W ₀ −2)
× 100 (%) (b) W ₀ g was obtained by impregnating the polymer A with 2 g of polypropylene non-woven fabric so that the total weight was about 5 g. The weight after immersion in 300 mL of dimethylformamide for 60 minutes was defined as W ₂ g by the following equation. Weight loss rate = (W ₀ −W ₂ ) / (W ₀ −2) × 100
(%) (C) The polymer A was impregnated and impregnated into 2 g of a nonwoven fabric of polypropylene so that the total weight was about 5 g, and the resulting product was W ₀ g, and this was kept at 98 ° C. in a thermostat. The weight after immersion in hot water for 30 minutes was defined as W ₃ g according to the following equation. Weight loss rate = (W ₀ −W ₃ ) / (W ₀ −2) × 100
(%) (3) 100% elongation modulus A dumbbell-shaped test piece was prepared from a 100 μm-thick film made of polymer B, and a pulling speed of 300 was used.
At 100 cm / min, the stress at 100% elongation was measured according to the method specified in JIS K7311. (4) Weight Swelling Rate 2 g of a 100 μm thick film made of polymer B (W ₀
g) at 200C in N, N-dimethylformamide 300m
The weight after immersion in L for 60 minutes was determined as W ₄ g by the following equation.

Weight swelling ratio = (W ₄ −W ₀ ) / W ₀ × 100 (%) (5) Breaking strength A dumbbell-shaped test piece was prepared from a 100 μm thick film made of polymer B in the same manner as in (3) above. It was prepared and used to measure the breaking strength at a tensile speed of 300 cm / min according to the method specified in JIS K7311. Example 1 30 parts of polyethylene terephthalate obtained by copolymerizing 8% by mole of 5-sodium sulfoisophthalic acid as a sea component,
Polyethylene terephthalate as an island component is a form comprising 70 parts of polyethylene island terephthalate, and 36 filaments are included in one filament, and the average fineness is 3.8 dtex. After forming, a needle punch was performed to prepare a nonwoven fabric.

An aqueous solution of polyvinyl alcohol having a saponification degree of 98% was applied to the island fiber by 30% by weight to the sheet made of the nonwoven fabric by an impregnation method, dried, and then subjected to a heat treatment at 150 ° C. The above polyvinyl alcohol is added at 40 ° C
The rate of weight loss after immersion in a 0% by weight aqueous sodium hydroxide solution for 20 minutes is 3%, and the rate of weight loss after immersion in N, N-dimethylformamide for 60 minutes is 3%. The weight reduction rate after immersion for 100 minutes was 100%. To this sheet, a polycarbonate-based polyurethane dispersed in water was applied at 50% by weight based on the island fibers. The 100% elongation modulus after immersing this polyurethane in a 1.0% by weight aqueous sodium hydroxide solution at 90 ° C. for 30 minutes is 60 kg / cm ² , and the weight swelling ratio after immersion in N, N-dimethylformamide for 30 minutes is as follows: Breaking strength after immersion in hot water of 220% and 98 ° C. for 30 minutes is 315 kg / c.
m ² .

Next, the sheet was heated to 60 ° C.
The sea component was removed using an aqueous sodium hydroxide solution.

The treated sheet was subjected to a polyvinyl alcohol removal treatment using hot water at 90 ° C.

Next, this sheet was sliced and buffed, and then dyed with a disperse dye in a circular dyeing machine.

The leather-like sheet obtained was rich in durability and had good physical properties. Example 2 A nonwoven fabric obtained in the same manner as in Example 1 was provided with 50% by weight of a polycarbonate-based polyurethane dispersed in water by an impregnation method based on the island fibers. This polyurethane was heated at 90 ° C.
The 100% elongation modulus after immersion in a 0% by weight aqueous sodium hydroxide solution for 30 minutes is 60 kg / cm ² ,
The weight swelling ratio after immersion in N-dimethylformamide for 30 minutes was 220%, and the rupture strength after immersion in hot water at 98 ° C. for 30 minutes was 315 kg / cm ² . To this sheet, an aqueous solution of polyvinyl alcohol having a saponification degree of 98% was applied to the island fiber by 30% by weight by an impregnation method, dried, and then dried.
Heat treatment was performed at 0 ° C. The weight loss rate after immersing the above-mentioned polyvinyl alcohol in a 10% by weight aqueous sodium hydroxide solution at 40 ° C. for 20 minutes is 3%, the weight loss rate after immersing in N, N-dimethylformamide for 60 minutes is 3%, 9
The weight loss rate after immersion in hot water at 8 ° C for 30 minutes is 100
%Met.

Next, the sheet was heated to 60 ° C.
The sea component was removed using an aqueous sodium hydroxide solution.
The treated sheet was subjected to a polyvinyl alcohol removal treatment using hot water at 90 ° C.

Next, this sheet was sliced and buffed, and then dyed with a disperse dye in a circular dyeing machine.

The leather-like sheet obtained was rich in durability and had good physical properties. Example 3 A nonwoven fabric obtained in the same manner as in Example 1 was saponified by an impregnation method with a degree of saponification of 9.
8% aqueous solution of polyvinyl alcohol is applied to
After giving 0 wt% and drying, it was subjected to a heat treatment at 150 ° C. 10% by weight of the above polyvinyl alcohol at 40 ° C
The weight loss rate after immersion in sodium hydroxide aqueous solution for 20 minutes is 3%, the weight loss rate after immersion in N, N-dimethylformamide for 60 minutes is 3%, and 30% in 98 ° C. hot water.
The weight reduction rate after immersion for 100 minutes was 100%. To this sheet, 5% by weight of a polycarbonate-based polyurethane dispersed in water was applied to the island fibers. This polyurethane was placed in a 1.0% by weight aqueous solution of sodium hydroxide at 90 ° C.
100% elongation modulus after immersion for 0 minutes is 60 kg
/ Cm ² , the weight swelling ratio after immersion in N, N-dimethylformamide for 30 minutes is 220%, and 30% in hot water at 98 ° C.
The breaking strength after immersion for a minute was 315 kg / cm ² .

Next, the sheet was heated to 60 ° C.
The sea component was removed using an aqueous sodium hydroxide solution.

The treated sheet is impregnated with 40% by weight of a dimethylformamide solution of polyurethane with respect to the island fibers, wet coagulated, and subjected to a treatment for removing polyvinyl alcohol (and simultaneously removing dimethylformamide) using hot water at 90 ° C. gave.

Next, this sheet was sliced and buffed, and then dyed with a disperse dye in a circular dyeing machine.

The obtained leather-like sheet was excellent in durability and had good physical properties. Comparative Example 1 The nonwoven fabric obtained in the same manner as in Example 1 was impregnated with 30 parts of an aqueous solution of polyvinyl alcohol having a saponification degree of 88% with respect to the island fiber and dried. The treatment after the fiber expression treatment was performed. The weight loss rate after immersing the above-mentioned polyvinyl alcohol in a 10% by weight aqueous solution of sodium hydroxide at 40 ° C. for 20 minutes is 20%.
%, The rate of weight loss after immersion in N, N-dimethylformamide for 60 minutes was 3%, and the rate of weight loss after immersion in hot water at 98 ° C. for 30 minutes was 100%.

The resulting leather-like sheet-like material showed polyvinyl alcohol eluted during the ultrafine fiber expression treatment, and became paper-like without flexibility. Comparative Example 2 The nonwoven fabric obtained in the same manner as in Example 1 was impregnated with 30 parts of an aqueous polyvinyl alcohol solution with respect to the island fiber, dried, and then dried.
A 100% elongation modulus after immersion in a 1.0% by weight aqueous sodium hydroxide solution at 0 ° C. for 30 minutes is 140 kg /
cm ^2, N, N-dimethylformamide in 30 minutes immersed weight swelling ratio after 400% impart water-dispersible polyurethane rupture strength is 40 kg / cm ² after immersion for 30 minutes in hot water at 98 ° C. After that, a treatment subsequent to the ultrafine fiber development treatment was performed in the same manner as in Example 1.

The above-mentioned polyvinyl alcohol was heated at 40 ° C.
0.5% weight loss after immersion in 0% by weight aqueous sodium hydroxide solution for 20 minutes, 3% weight loss after immersion in N, N-dimethylformamide for 60 minutes, 98 ° C hot water The weight loss after immersion in the sample for 30 minutes was 100%.

The leather-like sheet obtained had a rough surface quality, a short nap and a paper-like feel. Comparative Example 3 30 parts of polyethylene terephthalate obtained by copolymerizing 8-sodium sulfoisophthalic acid with 8 mol% as a sea component,
Polyethylene terephthalate as an island component is a form comprising 70 parts of polyethylene island terephthalate, and 36 filaments are included in one filament, and the average fineness is 3.8 dtex. After forming, a needle punch was performed to prepare a nonwoven fabric.

The sheet composed of the nonwoven fabric was subjected to removal of sea components using a 10% aqueous sodium hydroxide solution heated to 60 ° C.

The sheet was impregnated with 30 parts of an aqueous solution of polyvinyl alcohol having a saponification degree of 98% with respect to the island fiber, dried and then heat-treated at 150 ° C. The weight loss rate after immersing the above-mentioned polyvinyl alcohol in a 10% by weight aqueous solution of sodium hydroxide at 40 ° C. for 20 minutes is 3%, and the weight loss rate after immersion in N, N-dimethylformamide for 60 minutes is 3%. The weight loss rate after immersion in hot water of 98 ° C. for 30 minutes was 100%.

Next, a dimethylformamide solution of polyurethane was applied to the above-mentioned heat-treated sheet for 40% against the island fiber.
Part is impregnated, wet coagulated, and de-polyvinyl alcohol using 90 ° C hot water (simultaneously with de-dimethylformamide)
Processing was performed.

Next, this sheet was sliced and buffed, and then dyed with a disperse dye in a circular dyeing machine.

The obtained leather-like sheet material had a coarse quality and a paper-like texture.

[0054]

According to the method for producing a leather-like sheet of the present invention, a leather-like sheet having good quality and texture can be obtained, and at least the composite fiber can be obtained without using an organic solvent. Since one component is removed, the burden on the environment can be reduced.

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Claims (6)

[Claims] 1. A method for producing a leather-like sheet, comprising: A step of preparing a sheet using ultrafine fiber-expressing fibers composed of a combination of two or more polymer substances having different solubility in an aqueous alkali solution. 2. A step of applying a polymer A satisfying all the following characteristics (1) to (3) to the sheet. (1) The weight loss rate after immersion in a 10% by weight aqueous sodium hydroxide solution at 40 ° C. for 20 minutes is 10% or less. (2) The weight loss after immersion in N, N-dimethylformamide for 60 minutes is 5% or less. (3) The weight loss rate after immersion in hot water of 98 ° C. for 30 minutes is 95% or more. 3. A step of impregnating the sheet with an aqueous dispersion of the polymer B that satisfies all of the following properties (1) to (3) to give the polymer B: (1) 100% elongation modulus after immersion in a 1.0% by weight aqueous sodium hydroxide solution at 90 ° C. for 30 minutes is 10
~80kg / cm ^2. (2) The weight swelling ratio after immersion in N, N-dimethylformamide for 30 minutes is 300% or less. (3) Breaking strength after immersion in hot water of 98 ° C. for 30 minutes is 100 kg / cm ² or more. 4. A step of treating the sheet with an aqueous alkaline solution to develop ultrafine fibers. In this order or in the order in which 2 and 3 are interchanged. 2. The method for producing a leather-like sheet according to claim 1, wherein after steps 1 to 4 of claim 1, the sheet is impregnated with a solution of polyurethane to give the polyurethane. 3. A method for producing a leather-like sheet, comprising: A step of preparing a sheet using ultrafine fiber-expressing fibers composed of a combination of two or more polymer substances having different solubility in an aqueous alkali solution. 2. A step of applying a polymer A satisfying all the following characteristics (1) to (3) to the sheet. (1) The weight loss rate after immersion in a 10% by weight aqueous sodium hydroxide solution at 40 ° C. for 20 minutes is 10% or less. (2) The weight loss after immersion in N, N-dimethylformamide for 60 minutes is 5% or less. (3) The weight loss rate after immersion in hot water of 98 ° C. for 30 minutes is 95% or more. 3. A step of impregnating the sheet with an aqueous dispersion of the polymer B that satisfies all of the following properties (1) to (3) to give the polymer B: (1) 100% elongation modulus after immersion in a 1.0% by weight aqueous sodium hydroxide solution at 90 ° C. for 30 minutes is 10
~80kg / cm ^2. (2) The weight swelling ratio after immersion in N, N-dimethylformamide for 30 minutes is 300% or less. (3) Breaking strength after immersion in hot water of 98 ° C. for 30 minutes is 100 kg / cm ² or more. 4. A step of treating the sheet with an aqueous alkaline solution to develop ultrafine fibers. 5. A step of impregnating and applying a polyurethane solution to the sheet. Are carried out in this order. 4. The method for producing a leather-like sheet according to claim 1, wherein the polymer A is a polyvinyl alcohol having a saponification degree of 90% or more. 5. The method according to claim 1, wherein after applying the polymer A to the sheet, the sheet is heated to 130 ° C. or higher.
5. The method for producing a leather-like sheet according to any one of items 4. 6. A leather-like sheet having a fineness of 0.3 dte.
4. An ultrafine fiber of x or less, a polyurethane soluble in N, N′-dimethylformamide and a polyurethane insoluble in N, N′-dimethylformamide. A method for producing a leather-like sheet.