JP2002348784A - Method for producing artificial leather having excellent stretchability - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing artificial leather having excellent shrinkability without lowering surface qualities of artificial leather. SOLUTION: In this method for producing artificial leather having excellent stretchability, at least one side of artificial leather constituted of a fiber interlaced body mainly comprising an extra fine fiber having <=0.9 dtex single fiber fineness and a polymer elastic body is provided with a film surface of the polymer elastic body and the artificial leather is drawn by strength of >=20% and <=90% strength at break of the artificial leather in the length direction and/or width direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing artificial leather having excellent elasticity.

[0002]

2. Description of the Related Art Artificial leather made of a conventional nonwoven fabric has poor elasticity, and in particular, has little elasticity in the longitudinal direction. This is due to the fact that tension is constantly applied in the length direction in the manufacturing process, and the length is increased.

[0003] In the width direction, since it is processed in a relaxed state in the manufacturing process, it is easy to impart elasticity compared to the length direction, but it satisfies the elongation rate and the elongation recovery rate which are indicators of elasticity. Has not been obtained.

Japanese Patent Application Laid-Open No. 2000-303365 suggests a method of imparting a stretch in the longitudinal direction by overfeeding and heat-treating before dyeing. However, this method is extremely limited. It is effective only for it and is hardly general.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing artificial leather having excellent stretchability without deteriorating the surface quality of artificial leather.

[0006]

The present invention employs the following means to solve the above-mentioned problems.

That is, the method of the present invention for producing an artificial leather having excellent stretchability comprises at least one surface of an artificial leather mainly composed of a fiber entangled body containing ultrafine fibers having a single fiber fineness of 0.9 dtex or less and a polymer elastic body. After the film surface of the elastic polymer is formed, the artificial leather is subjected to 20% of its breaking strength.
It is characterized by being stretched in the length direction and / or the width direction with a strength of 90% or less.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail.

In the present invention, the artificial leather having excellent elasticity is provided on at least one surface of an artificial leather mainly composed of a fiber entangled body containing ultrafine fibers having a single fiber fineness of 0.9 dtex or less and an elastic polymer. After forming the membrane surface of the elastic body, the artificial leather sheet is subjected to at least 20% of its breaking strength by 9%.
It is manufactured by a method of stretching in the length direction and / or the width direction with a strength of 0% or less.

Examples of the polymer forming the ultrafine fibers include polyamides such as nylon 6, nylon 66, nylon 12, and copolymerized nylon, polyethylene terephthalate, polybutylene terephthalate, polypropylene terephthalate and / or copolymers thereof. Examples thereof include polyesters, but are not particularly limited.

The fineness of the ultrafine fibers is 0.9 dtex or less, preferably 0.0001 dtex or more and 0.9 dt or less.
ex or less. If the fineness of the ultrafine fibers exceeds 0.9 dtex, a soft touch on the surface unique to artificial leather cannot be obtained, which is not preferable. Fineness of microfiber is 0.0001
If it is less than dtex, the fiber strength is undesirably low.

As the combination of the ultrafine-thinning fibers and the polymer which is removed by dissolution or physical or chemical action, the polyesters such as polyethylene terephthalate, polybutylene terephthalate, polypropylene terephthalate and / or copolymers thereof are used. And polyamides such as nylon 6, nylon 66, nylon 12, and copolymerized nylon; and polyolefins such as polyethylene and polystyrene.

In order to obtain the fiber entangled sheet used in the present invention, for example, a method of forming short fibers of ultrafine fiber-generating conjugate fibers into a web and forming the web by entanglement means such as a needle punch or a water jet punch may be mentioned. However, it is not particularly limited.

In the method of the present invention, ultrafine fibers can be expressed by desealing with sea-island fibers, alkali treatment with split fibers, mechanical stimulation such as abrasion, beating, etc. .

In the present invention, a polymer elastic body is provided to the fiber entangled body containing the ultrafine fibers, the ultrafine fiber bundle, or the ultrafine fiber-generating conjugate fiber. The polymer elastic body may be provided before or after the ultrafine fiber generating composite fiber is subjected to the ultrafine treatment.

Examples of such a polymer elastic body include polyurethane elastomer, polyurea elastomer, polyurethane / polyurea elastomer, polyacrylic resin, acrylonitrile / butadiene elastomer, and styrene / butadiene elastomer.
Among them, polyurethane elastomers such as polyurethane elastomer, polyurea elastomer, and polyurethane / polyurea elastomer are preferable. As these polyurethane elastomers, for example, it is preferable to use at least one selected from polymer diols having an average molecular weight of 500 to 3500, such as polyester diol, polyether diol, polyester polyether diol, polylactone diol, and polycarbonate diol. .

From the viewpoint of the durability of the product, polyurethane using a polymer diol containing 30% by weight or more and 90% by weight or less of a polycarbonate diol is more preferable. If the content of the polycarbonate diol is less than 30% by weight, the durability decreases, and if it exceeds 90% by weight, the feeling becomes hard, which is not preferable.

The polycarbonate diol referred to in the present invention is a polycarbonate diol in which the diol skeleton is linked via a carbonate bond to form a polymer chain, and has a hydroxyl group at both ends. The diol skeleton is determined by the glycol used as a raw material, but its type is not particularly limited. For example, 1,6-hexanediol, 1,5-
Pentanediol, neopentyl glycol, and 3-methyl-1,5-pentanediol can be used.
In addition, at least two selected from these glycol groups
A copolymerized polycarbonate diol using at least one kind of glycol as a raw material is preferable because artificial leather having particularly excellent flexibility and appearance can be obtained.

When an artificial leather having particularly excellent flexibility is obtained, it is preferable to introduce a bond other than a carbonate bond into the polymer diol, for example, an ester bond, an ether bond or the like, as long as the durability is not impaired.

As a form for introducing such a chemical bond,
It is possible to employ a method in which a polycarbonate diol and a polymer diol other than the above are individually polymerized and used in combination at an appropriate ratio during the polymerization of polyurethane.

The amount of the elastic polymer is preferably in the range of 10 to 70% by weight in terms of solid content with respect to the weight of microfibers in view of the flexibility, surface touch, and uniformity of dyeing of the product. When the coating weight is less than 10% by weight, the abrasion tends to decrease, and the coating weight is 7%.
If it exceeds 0% by weight, the hand tends to be hard.

If necessary, additives such as a coloring agent, an antioxidant, an antistatic agent, a dispersant, a softener, and a coagulation regulator may be added to the elastic polymer.

Next, at least one surface of the sheet is raised to form a fiber raised surface. Various methods such as buffing with sandpaper or the like are used as a method for forming the fiber nap surface.

Subsequently, a film surface of a polymer elastic material is formed on at least one surface of the artificial leather sheet obtained as described above. Various conventionally known methods can be used as the film surface forming method.

For example, a polymer elastic material is adjusted to an appropriate concentration, and at least one surface of artificial leather is subjected to reverse roll coating, gravure coating, knife coating,
After applying the polymer elastic body by a method such as slit coating or spraying, a method of solidifying by wet or dry method to integrate the fiber and the polymer elastic body resin can be used. As another method, a method in which a film of a polymer elastic body is partially or entirely adhered to at least one surface of artificial leather with an adhesive can be used.

As described above, the polymer elastic body used for forming the film surface of the polymer elastic body on at least one surface of the artificial leather sheet may be the same as that given to the fiber entangled body as the binder. Although different materials may be used, it is preferable to use polyurethane in terms of stretchability and practicality.

Although the film surface is not particularly limited, according to various findings of the present inventors, the film thickness is 3 to 40.
μm, and the membrane weight is about 5 to 50 g / m ² ,
This is favorable because a higher effect can be obtained.

In the artificial leather in which the film surface of the polymer elastic body is formed on at least one surface, the artificial leather before forming the film surface of the polymer elastic body is regulated to have a low elasticity, so that it is not sufficient. The elasticity cannot be obtained.

In the present invention, elasticity is imparted by further performing the following processing. That is, the artificial leather in which the film surface of the polymer elastic body is formed on at least one surface is used to reduce the breaking strength of the artificial leather from 20% to 90%, preferably from 30% to 80%.
% Or less, more preferably 40% or more and 80% or less, in the length direction and / or the width direction. The stretching treatment can be performed using a spreading device such as a tenter.

In this case, the film may be stretched separately in the length direction and the width direction, but preferably, the film is stretched simultaneously in the length direction and the width direction. At the time of stretching, the sheet may be treated at room temperature. However, if the sheet is heated with dry heat or wet heat, the sheet can be stretched more strongly and stably, and the stretchability can be improved. However, heating at or above the heat setting temperature of the sheet is not preferred because the elasticity tends to be lost. If the strength of the stretching treatment is less than 20% of the breaking strength of the artificial leather, it is not preferable because sufficient elasticity is difficult to obtain, and if it exceeds 90%, the sheet is likely to break during processing, which is not preferable.

The sheet thus obtained has elasticity as it is. However, by performing a heat treatment in a heated liquid, the residual strain generated during the stretching treatment can be reduced and the elasticity can be improved. As a method of performing heat treatment in a heated liquid, a liquid jet dyeing machine such as Circular or Uniace can be used. By simultaneously dyeing, it is possible to increase the added value of the product.

The artificial leather obtained by the method of the present invention comprises
In general, the elongation is in the range of 10-30%, particularly preferably made 20-30%, and the elongation recovery is in the range of 80-95%, particularly preferably made 85. The range is ~ 95%.

This is because, in the light of the fact that the same kind of the prior art has a stretch ratio of only about 3 to 10% and a stretch recovery rate of only about 70 to 85%, especially in the length direction, it is extremely stretchable. It can be said that excellent epoch-making, and particularly, excellent epoch-making production of artificial leather is realized in that two-way stretching is enabled.

[0034]

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples.

The elongation rate and elongation recovery rate in the examples were measured by the following methods. (1) Elongation rate: Three samples each of 5 cm × about 30 cm are taken in the length direction and the width direction, and a constant-speed elongation type tensile tester is used to set a gripping distance to 20 cm and a tensile speed of 2
It is stretched to 1.8 kg at 0 cm / min, the gripping interval at that time is measured, and the extension rate (%) is obtained by the following equation.
The average of three images is shown.

Elongation rate (%) = (L1-L) / L × 100 L: gripping distance L1: gripping distance when stretched to 1.8 kg (2) Elongation recovery rate: 5 cm × about 30 cm sample length Three samples were taken in each of the width direction and the width direction, using a constant-speed elongation type tensile tester, the gripping interval was set to 20 cm, and then the elongation was increased to 80% of the elongation rate separately obtained by the above method, and left for 1 minute. Then, return to the original position at the same speed and leave for 3 minutes. After repeating this operation five times, the elongation when stretched to a load equivalent to the weight of the sample is defined as the residual elongation after repeated five times, and the elongation recovery rate (%) is calculated by the following equation
And an average value of three images is shown.

Elongation recovery rate (%) = (L2−L3) / L2 × 100 L2: Length on chart corresponding to 80% elongation of elongation rate L3: Chart corresponding to residual elongation after repeated 5 times elongation Example 1 Carding and wrapping using raw cotton of a polymer mutual array fiber having a composite fineness of 3.0 dtex, an island fineness of 0.05 dtex, and a fiber length of 51 mm made of polyethylene terephthalate as the island component and polystyrene as the sea component, and having a fiber length of 51 mm 2500 fiber / cm ²
Was subjected to needle punching to prepare a nonwoven fabric sheet.

This sheet is immersed in boiling water to shrink,
Then, after polyvinyl alcohol is applied, the sea component is dissolved and removed with trichlene to express ultrafine fibers, and polyurethane obtained by applying about 25% by weight based on the sheet weight is sliced, and then subjected to a buffing treatment with a buffing machine. ,
The back surface of the sheet was coated with polyurethane to form a polyurethane thin film. The breaking strength of this sheet is
It was 5.9 kg / cm in the length direction and 4.1 kg / cm in the width direction.

Next, this sheet was stretched in the length and width directions at 70% of the breaking strength to develop elasticity.
Then, using a circular dyeing machine, it was dyed brownish with a disperse dye.

The results of evaluation of the artificial leather thus obtained are shown in Table 1. The elongation rate is 15% or more and the elongation recovery rate is 85% or more in both the length and width directions. Was good. Comparative Example 1 Napped artificial leather was obtained in the same manner as in Example 1 except that the stretching treatment was not performed.

The evaluation results are as shown in Table 1. The film had moderate stretchability in the width direction, but had an elongation ratio of 10% or less in the length direction and hardly any stretchability. Comparative Example 2 Napped artificial leather was obtained in the same manner as in Example 1 except that the stretching treatment was performed at a strength of 10% of the breaking strength of the sheet.

The evaluation results are as shown in Table 1. The sheet had moderate stretchability in the width direction, but had an elongation ratio of 10% or less in the length direction and almost no stretchability. Comparative Example 3 Napped artificial leather was obtained in the same manner as in Example 1 except that no polyurethane film was formed on the back surface of the sheet and no stretching treatment was performed.

The evaluation results are as shown in Table 1.
In both width directions, the elongation recovery rate was 80% or less, and there was almost no elasticity.

[0044]

[Table 1]

[0045]

According to the present invention, it is possible to provide a method for producing artificial leather having excellent elasticity without deteriorating the surface quality of artificial leather.

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Claims (5)

[Claims] 1. After forming a film surface of a polymer elastic body on at least one surface of an artificial leather mainly composed of a fiber entangled body containing ultrafine fibers having a single fiber fineness of 0.9 dtex or less and a polymer elastic body, A method for producing artificial leather having excellent elasticity, characterized in that the artificial leather is stretched in a length direction and / or a width direction at a strength of 20% to 90% of its breaking strength. 2. The method according to claim 1, wherein the film surface of the elastic polymer is made of polyurethane. 3. A method for forming a film surface of an elastic polymer,
3. The method according to claim 1, wherein at least one surface of the artificial leather is coated with an elastic polymer. 4. When forming a film of a polymer elastic body on at least one surface of artificial leather, the film surface is formed by partially or entirely adhering the polymer elastic material on at least one surface of the artificial leather. The method for producing artificial leather having excellent elasticity according to claim 1 or 2, wherein the artificial leather is excellent in elasticity. 5. A polyurethane using a polymer diol containing at least 30% by weight of a polycarbonate diol as a polymer elastic body.
3. The method for producing an artificial leather excellent in elasticity according to 3 or 4.