JP2002030577A - Method for producing leathery sheet-like product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a leathery sheet-like product, wherein one component of the conjugate fiber is removed without using any organic solvent. SOLUTION: This method for producing a leathery sheet-like product comprises the following consecutive steps: 1. A sheet is made using ultrafine fiber-developing fibers consisting of a combination of at least two polymeric substances differing in solubility to an aqueous alkaline solution from each other, 2. the sheet is incorporated with a reinforcer meeting all of the following requirements: (1) percent weight reduction after immersed in a 10 wt.% aqueous sodium hydroxide solution at 40 deg.C for 20 min is <=10 wt.%, (2) percent weight reduction after immersed in N,N-dimethylformamide for 60 min is <=5 wt.% and (3) percent weight reduction after immersed in hot water at 98 deg.C for 30 min is >=95 wt.%, 3. the resulting sheet is treated with an aqueous alkaline solution to develop ultrafine fibers while substantially keeping the form of the sheet, 4. the sheet thus treated is impregnated with a solution or emulsion of a polymeric elastomer to incorporated the sheet with the polymeric elastomer, and 5. part or the whole of both the reinforcer and the solvent for the polymeric elastomer in the resultant sheet is removed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an environment-friendly method for producing a leather-like sheet. More specifically, it relates to a method for removing one component of a conjugate fiber without using an organic solvent in the production of a leather-like sheet.

[0002]

2. Description of the Related Art A leather-like sheet obtained by providing a polymer sheet with a polymer elastic material is widely used for both clothing and materials. In particular, leather-like sheet materials using ultrafine fibers of 0.3 dtex or less have a texture and touch similar to that of natural leather, and their use has been expanding in recent years. As a means for obtaining the ultrafine fibers, a method of producing a sea-island type composite fiber or a polymer blend fiber using a plurality of polymer substances, and removing one of the components with an organic solvent, the resulting fiber is thin, fiber It has been widely adopted because it has a moderate space between them and has excellent flexibility.

In recent years, there has been a concern that the use of an organic solvent may adversely affect the environment, and there has been a demand for the production of such a leather-like sheet without using an organic solvent. For example, an ultrafine fiber expression treatment using an alkaline aqueous solution is disclosed in JP-A-6-316814, but in this treatment, a reinforcing agent cannot be added, and compared with a treatment using an organic solvent for the extrafine fiber expression treatment. Only the texture and quality were inferior.

[0004]

SUMMARY OF THE INVENTION In view of the background of the prior art, the inventors have made intensive studies and, as a result, have reached the present invention. That is, after applying a reinforcing agent to the ultrafine fiber-expressing fiber sheet, the ultrafine fibers are expressed by an alkaline aqueous solution without using an organic solvent, and thereafter, a polymer elastic body of a solution type or an emulsion is provided, and the reinforcing agent and the reinforcing agent are added. It has been found that the molecular elastic body and the fiber improve the adhesion without impairing the feeling, and that a leather-like sheet having excellent feeling and durability can be obtained while reducing the load on the environment.

[0005]

SUMMARY OF THE INVENTION The present invention has the following arrangement in order to solve the problems of the prior art.
That is, a method for producing a leather-like sheet material, A step of forming a sheet using ultrafine fiber-expressing fibers composed of a combination of at least two or more types of polymer substances having different solubility in an aqueous alkali solution. 2. A step of applying a reinforcing agent that satisfies all of 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 rate 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 treating the sheet with an aqueous alkali solution to develop ultrafine fibers while substantially maintaining the shape of the sheet. 4. A step of impregnating the sheet with a solution or emulsion of a polymer elastic body to give the polymer elastic body. 5. A step of removing part or all of the solvent for the reinforcing agent and the elastic polymer in the sheet. Are carried out in this order.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the production of a leather-like sheet according to the present invention, a sheet is first prepared using ultrafine fiber-expressing fibers comprising a combination of two or more polymer substances having different solubilities in an aqueous alkaline solution. A process is required.

In the present invention, a polymer substance having a different solubility in an aqueous alkali 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.

In the present invention, the polymer substance having high solubility in an aqueous alkali solution is not particularly limited, but from the viewpoint of alkali dissolution rate and spinning stability, 5-sodium sulfoisophthalic acid, polyethylene glycol, sodium dodecylbenzenesulfonate. , A bisphenol A compound, isophthalic acid, adipic acid, dodecadionic acid, cyclohexylcarboxylic acid, etc., in a copolymerized polyester of 5 to 20 mol% is preferred. In particular, from the viewpoint of heat resistance and weak alkali solubility, 5-sodium sulfoisophthalic acid is added to 5 to 2
It is more preferable to use a polyethylene terephthalate copolymer copolymerized with 0 mol%. Further, these copolymers may be not only binary but also multi-component copolymers of three or more.

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

The present invention is characterized in that ultrafine fibers are expressed using an alkaline aqueous solution. Such an alkaline aqueous solution is not particularly limited, and may be an aqueous sodium hydroxide solution, an aqueous potassium hydroxide solution, an aqueous ammonia solution. Salts and the like can be used. Further, it is preferable to perform the treatment while appropriately applying heat in order to increase the efficiency of the treatment.

Examples of the form of the ultrafine fiber-expressing fiber include high molecular mutual alignment fibers as disclosed in JP-B-48-22126, JP-B-51-21041, and JP-B-6-218.
It is preferable to appropriately select and use a mixed spun fiber disclosed in Japanese Patent Application Laid-Open No. 0-21904, a splittable conjugate fiber disclosed in Japanese Patent Application Laid-Open No. 9-310230, or the like according to the purpose. The fineness of the ultrafine fibers obtained from such fibers is 0.3 dt
ex or less is preferred in terms of texture such as flexibility.

The single fiber fineness is preferably 0.3 dtex or less, 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 be in the state where it was done.

[0013] In forming such an ultrafine fiber-expressing fiber into a sheet, the form is not particularly limited, and a woven fabric, a knitted fabric, a nonwoven fabric and the like can be preferably used, but a nonwoven fabric is preferred in terms of flexibility and texture. More preferred. 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. The method for producing the nonwoven fabric may be any of a spun bond method, a melt blow method, a flash spinning method, a paper making method, a card method, and the like, and if necessary, may be entangled by a needle punch method, a hydroentanglement method, or the like.

In the present invention, a specific polymer substance is added to the above-mentioned nonwoven fabric as a reinforcing agent.

[0015] As such a polymer substance, (1) the weight reduction 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 rate after immersion in N, N-dimethylformamide for 60 minutes is 5% or less. (3) Weight loss rate after immersion in hot water of 98 ° C for 30 minutes
95% or more. It is necessary to satisfy all the characteristics.

The weight reduction rate of (1) is preferably 5% or less, more preferably 3% or less. Further, the weight reduction rate of (2) is preferably 3% or less. Further, the weight reduction rate of (3) is preferably 97% or more, and more preferably 100%.

By having such properties, it is possible to control the form of the felt and the function retention during the process of developing ultrafine fibers, and to control the adhesiveness with polyurethane, so that the quality, texture and physical properties can be arbitrarily controlled according to the purpose.
As such a high molecular substance, an organic substance such as polyvinyl alcohol or a derivative thereof, water-soluble starch, carboxymethyl cellulose, partially saponified acrylate, polyacrylamide, and cellulose acetate is preferable.
When polyvinyl alcohol having a saponification degree of less than 90% is used as a reinforcing agent, it is eluted into an aqueous alkali solution and the effect of maintaining the form and function of the felt becomes insufficient. Is preferable, and polyvinyl alcohol having a saponification degree of 95% or more is more preferable.

In order to reduce the solubility in an aqueous alkali solution, it is preferable to apply a heat treatment after applying these reinforcing agents to the nonwoven fabric, since it is extremely effective. The temperature of this heat treatment is preferably 130 ° C. or higher, more preferably 130 ° C. to 195 ° C. If the temperature is lower than 130 ° C., the effect is insufficient, so that it is not preferable. If the temperature is higher than 195 ° C., it may be insoluble and may not be removed. The temperature of the heat treatment is more preferably 150 ° C. to 190 ° C. from the viewpoint of easy control in the removal treatment of the reinforcing agent. The processing time depends on the form of the sheet and the performance of the heat treatment equipment,
It can be determined appropriately according to the purpose.

In the present invention, an aqueous alkaline solution is used as a solvent to be removed during the ultrafine fiber development treatment, and if necessary, operations such as heating, stirring, and squeezing are performed to obtain fibers in the nonwoven fabric to which a reinforcing agent has been added. The easily soluble components of are removed. 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.

Next, the treatment for applying the solution or emulsion of the elastic polymer is performed by impregnation, spraying, coating or the like, followed by dry coagulation with heat, wet coagulation with water, steam treatment as appropriate, etc. Can be processed in the usual manner.

In the present invention, polyurethane, styrene-butadiene rubber, butadiene rubber, nitrile rubber, natural rubber, polyvinyl chloride, polyamide, polyamino acid, polyacrylic acid ester and the like can be preferably used as the polymer elastic body. Polyurethane is more preferable in terms of softening the texture.

In the present invention, dimethylformamide, methyl ethyl ketone, toluene, isopropyl alcohol, ethyl acetate, methylene glycol monoethyl ether and the like can be preferably used as the solvent for the polymer elastic material.

The total amount of the elastic polymer is preferably 20 to 120% by weight based on the fiber constituting the sheet.

In the present invention, the polymer elastic solution is applied, coagulated and immersed in warm water to remove the reinforcing agent, and then sliced and buffed as necessary by a conventional method to obtain the desired silver-attaching base. A material or a substrate for suede can be obtained. This substrate can be subjected to appropriate post-processing.

[0025]

The present invention will be described by the following 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 treating the treatment time as 1 hour according to the chemical resistance test of JIS K6911. (2) Weight loss rate (a) W ₀ g was obtained by impregnating a reinforcing agent with 2 g of polypropylene non-woven fabric so that the total weight was about 5 g, and this was W ₀ g. In 300 mL of a 10% by weight aqueous sodium hydroxide solution
The weight after immersion for one minute was defined as W ₁ g and was determined by the following equation. Weight loss rate = (W ₀ −W ₁ ) / (W ₀ −2) × 100
(%) (B) W ₀ g obtained by impregnating a reinforcing agent with 2 g of polypropylene non-woven fabric so that the total weight becomes approximately 5 g, and prepare W ₀ g, and this is 300 mL of N, N-dimethylformamide at 20 ° C. The weight after immersion in the steel 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) W ₀ g was obtained by impregnating a reinforcing agent with 2 g of polypropylene non-woven fabric so that the total weight was approximately 5 g, and this was W ₀ g, and this was kept at 98 ° C. in a thermostat. The weight after immersion in 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
Example 1 30 parts of polyethylene terephthalate obtained by copolymerizing 8 mol% of 5-sodium sulfoisophthalic acid as a sea component and 70 parts of polyethylene terephthalate as an island component contained 36 island island components in one filament. A staple of sea-island type fiber having an average fineness of 3.8 dtex was used to form a web through a card and a cross wrapper, and then a needle punch was performed to prepare a nonwoven fabric.

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. 20% by weight of the above-mentioned polyvinyl alcohol in a 10% by weight aqueous solution of sodium hydroxide at 40 ° C.
The weight loss after immersion in N, N-dimethylformamide for 3 minutes was 3%, and the weight loss after immersion for 3 minutes was 3%.
Weight loss rate after immersion in hot water at 8 ° C for 30 minutes is 100
%Met. Next, sea components were removed from this sheet using a 10% aqueous sodium hydroxide solution heated to 60 ° C. The sheet after this treatment was impregnated with 40 parts of a dimethylformamide solution of polyurethane with respect to the island fiber, wet-coagulated, and
Polyvinyl alcohol (and simultaneously dimethylformamide) treatment was performed using hot water at 0 ° C.

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 was rich 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. gave. 10 of 40 ° C of the above polyvinyl alcohol
The weight loss after immersion in a 20 wt% aqueous sodium hydroxide solution for 20 minutes is 20%, and 60% in N, N-dimethylformamide.
3% weight loss after immersion in hot water at 98 ° C
The weight loss rate after immersion for 30 minutes was 100%.

In the obtained leather-like sheet, polyvinyl alcohol was eluted during the ultrafine fiber development treatment, and it became paper-like without flexibility. Comparative Example 2 30 parts of polyethylene terephthalate obtained by copolymerizing 8 mol% of 5-sodium sulfoisophthalic acid as a sea component and 70 parts of polyethylene terephthalate as an island component in a ratio of 36 islands in one filament. Yes, a web was formed through a card and a cross wrapper using staples of sea-island type fibers having an average fineness of 3.8 dtex, and then a needle punch was performed to prepare a nonwoven fabric.

Sea components were removed from the sheet 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. 20% by weight of the above-mentioned polyvinyl alcohol in a 10% by weight aqueous solution of sodium hydroxide at 40 ° C.
The weight loss after immersion in N, N-dimethylformamide for 3 minutes was 3%, and the weight loss after immersion for 3 minutes was 3%.
Weight loss rate after immersion in hot water at 8 ° C for 30 minutes is 100
%Met. Next, the sheet after the treatment is impregnated with 40 parts of a dimethylformamide solution of polyurethane with respect to the island fiber, wet coagulated, and subjected to a treatment for removing polyvinyl alcohol (and simultaneously removing dimethylformamide) using hot water at 90 ° C. did.

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

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

[0034]

According to the production method of the present invention, since at least one component of the conjugate fiber is removed without using an organic solvent, it is possible to reduce the burden on the environment and to produce artificial leather having good quality and texture. Can be manufactured.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) D06M 15/333 D06M 15/564 15/564 101: 32 // D06M 101: 32 5/02 F F term ( Reference) 3B154 AA07 AA17 AB20 BA12 BA25 BB12 BB32 BD17 BE05 BF01 BF07 DA18 DA19 DA28 4F055 AA02 BA11 DA07 DA09 EA04 EA12 EA24 EA34 FA15 GA02 HA04 HA22 4L031 AA18 AB11 AB34 BA11 CA01 4L033 AA07 CA07 AC07

Claims (5)

[Claims] 1. A method for producing a leather-like sheet, comprising: A step of forming a sheet using ultrafine fiber-expressing fibers composed of a combination of at least two or more types of polymer substances having different solubility in an aqueous alkali solution. 2. A step of applying a reinforcing agent that satisfies all of 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 rate 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 treating the sheet with an aqueous alkali solution to develop ultrafine fibers while substantially maintaining the shape of the sheet. 4. A step of impregnating the sheet with a solution or emulsion of a polymer elastic body to give the polymer elastic body. 5. A step of removing part or all of the solvent for the reinforcing agent and the elastic polymer in the sheet. Are carried out in this order. 2. The method for producing a leather-like sheet according to claim 1, wherein the reinforcing agent is polyvinyl alcohol having a saponification degree of 90% or more. 3. A sheet provided with a reinforcing agent is heated to a temperature of 130 ° C. or higher to reduce the weight loss after immersion in a 10% by weight aqueous sodium hydroxide solution at 40 ° C. for 20 minutes.
% Or less, the method for producing a leather-like sheet according to claim 1 or 2. 4. The method for producing a leather-like sheet according to claim 1, wherein the ultrafine fibers produced by the treatment with the alkaline aqueous solution are polyester fibers having a fineness of 0.3 dtex or less. 5. A sheet provided with a reinforcing agent at 150 ° C. or higher
2. Heating to a temperature of less than 95 [deg.] C.
Or the method for producing a leather-like sheet according to item 3.