JPS61160487A - Production of synthetic leather - Google Patents

Abstract

PURPOSE:A fibrous base material which is formed by integrating a short-cut fiber-interlaced layer with a filament fiber-interlaced layer is filled with a polyurethane elastomer in its vacent spaces and coated with the same on its short-cut fiber layer. After coagulation, the filament-interlaced layer is removed to give a synthetic leather of high dimensional stability. CONSTITUTION:A short-cut fiber-interlaced layer 3 is integrated with a filament- interlaced layer 2, e.g., by needle-punching to form a fibrous base material 1. Then, the vacant spaces in the fibrous base material 1 are filled with a solution of a polyurethane elastomer in a water-miscible organic solvent such as dimethylformamide. Then, the solution is coagulation in a non-solvent maining consisting water and the short-cut fiber-interlaced layer 3 is coated with a solution of a polyurethane elastomer in a water-miscible organic solvent on its surface. The coating layer is coagulated in a non-solvent mainly consisting of water and dried to form a microporous layer 7 and the filament-interlaced layer 2 is removed to give the objective synthetic leather having a microporous layer with high dimensional stability.

Description

Detailed Description of the Invention (a) Industrial Application Field This invention relates to a method for manufacturing artificial leather, specifically a method for manufacturing artificial leather by a wet coagulation method, and more specifically, a method for manufacturing artificial leather by a wet coagulation method. The present invention relates to a method for producing artificial leather having layers.

(b) Conventional technology Artificial leather is used as a substitute for natural leather for shoes, clothing, bags, etc.
Artificial leather is used in many fields such as bags and industrial materials, and there is a demand for artificial leather with a flexible texture. Therefore, many manufacturing methods have been devised.

For example, short fiber entangled bodies (entangled bodies consisting of fibers with a size that can give a certain degree of elongation to artificial leather as a final product) are formed by water-soluble polymers such as polyvinyl alcohol, carboxymethyl cellulose, hydroxyethyl cellulose, and starch. For example, a method of impregnating and coating a tangled body consisting of fibers with a fiber length of 100111 or less is known (Conventional Example 1).

As another conventional example, a method is known in which a gauze-like fabric is inserted into a short fiber tangle (Conventional Example 2).

(c) Problems to be solved by the invention In Conventional Example 1, when the fiber weight of the short fiber entangled body is large, the dimensional stability is relatively good, but when the fiber weight is small, the water-soluble polymer is It easily melted, resulting in extremely poor dimensional stability, and when processed under tension, it had the disadvantage of easily becoming a product that was completely stretched in the direction of travel.

Conventional Example 2 was proposed for the purpose of eliminating the drawbacks of Conventional Example 1, but since the texture of the fabric is clearly visible in the cross section to the naked eye, its value as an artificial leather decreases, and its elongation is unnatural. Because of this, it had the disadvantage of being inferior in texture and being undesirable.

Furthermore, when a long-fiber entangled body consisting of fibers with a significantly longer fiber length than a short-fiber entangled body (having a substantially infinite fiber length) is used alone as a base material for artificial leather, the resultant artificial leather It did not have the necessary elongation during processing, so it was never used as a base material for artificial leather.

(D) Means for Solving the Problems This invention provides a long fiber entangled layer which has a substantially elongated short fiber entangled layer in the traveling direction and has a substantially infinite fiber length. After integrating the polyurethane elastomer into a fiber base material, a solution of the polyurethane elastomer in a water-miscible organic solvent is filled into the voids of the fiber base material, and then coagulated in a non-solvent mainly composed of water. Applying a water-miscible organic solvent solution of polyurethane elastomer to the layer surface, then coagulating in a non-solvent mainly composed of water, and then drying to form a microporous layer, and removing the long fiber entangled layer. Provided is a method for producing entrance leather characterized by the following.

The term "entangled long fiber layer" as used herein means a layer of entangled fibers having a substantially infinite fiber length, which is significantly longer than the fiber length of short fibers.

(E) Embodiment The following description will be made with reference to FIG. 1, which shows the process of an embodiment of the present invention, and FIGS. 2 and 3, which show the cross section of the fiber base material at points A and B during the process.

(1) is a fiber base material. The fiber base material (1) consists of a long fiber entangled nonwoven fabric layer (2) and a short fiber entangled nonwoven fabric layer (3). In this example, the long fiber entangled nonwoven fabric layer (2) is a so-called spunbond nonwoven fabric, and due to the manufacturing method, elongation in the direction of movement (tension direction) is extremely suppressed, and it has excellent dimensional stability in both dry and wet conditions. The fiber component used in the long fiber entangled nonwoven fabric layer (2) may be any commonly used fiber such as polypropylene, polyamide, polyester, etc. In addition, nonwoven fabrics made of entangled long fibers are coated with an adhesive to suppress fuzzing of the long fibers.
It may be a long fiber tangled nonwoven fabric obtained by a thermal bonding method that is embossed at a high temperature, or a long fiber tangled nonwoven fabric that is embossed at a high temperature after applying an adhesive.

As the fiber component of the short fiber entangled nonwoven fabric layer (3), polyamide, polyester, rayon, etc. are used in an appropriate combination.

Long fiber entangled nonwoven fabric layer (2) and short fiber entangled nonwoven fabric layer (
3) is laminated and integrated as shown in FIG. As a method for laminating and integrating, needle punching is preferable, but adhesives that do not swell or dissolve in a water-miscible organic solvent used to wash the fiber base material (1) later may be used for adhesion.

By needle punching, short fiber entangled nonwoven fabric layer (3
) and the entangled long fiber nonwoven fabric layer (2),
After the short fiber entangled nonwoven fabric layer (3) and the long fiber entangled nonwoven fabric layer (2), which have been previously made into an entangled body by needle punching, are superimposed, needle punching is performed from the short fiber entangled nonwoven fabric side to integrate them. is desirable.

Since the purpose of one lamination of the long fiber entangled nonwoven fabric layer (2) is to prevent expansion and contraction during processing of the short fiber entangled nonwoven fabric layer (3), excessive needle punching may cause
It is undesirable to transfer the short fibers of the short fiber entangled nonwoven fabric to the long fiber entangled nonwoven fabric. Short fiber entangled nonwoven fabric layer (
The thickness of the long fiber entangled nonwoven fabric layer (2) laminated on 3) is as follows:
Although it varies depending on the strength, length, etc. of the fibers constituting the rain woven fabric, it is necessary to have a reinforcing effect on the short fiber nonwoven fabric.

For example, in the case of a 1.5 to 3 denier 6 nylon or polyester spunbond nonwoven fabric, the weight is approximately 40 to 100 g/m'', although it varies depending on the conditions of heat fusion and adhesive.

In this example, a 1.5 denier 6 nylon spunbond nonwoven fabric (60 g/m'') was used as the long fiber entangled nonwoven fabric, and a 1.5 denier 6 nylon spunbond nonwoven fabric (fiber length 51 m+*) was used as the short fiber entangled nonwoven fabric. Non-woven fabric (100g/+”)
Using this method, the short fiber entangled nonwoven fabric layer (3) is superimposed on the long fiber entangled nonwoven fabric layer (2). Next, needle punching is performed from the short fiber tangled body side to obtain a thickness of 1. Oia
A + fiber base material (1) is obtained. (4) is a water-miscible organic solvent solution of a polyurethane elastomer (trade name: Crisbon, manufactured by Dainippon Ink); in this example, it is a dimethylformamide solution (solid content 16%); is impregnated and filled into the voids of the fiber base material (1). Examples of water-miscible organic solvents include dimethylformamide, dioxane, methyl ethyl ketone, and tetrahydrofuran, with dimethylformamide being the most preferred.

Then, the fiber base material (1) is squeezed with a squeezing roll (5). (6
) is a non-solvent whose main component is water, and the fiber base material (1) is immersed in it to coagulate the polyurethane. the result,
A nonwoven fabric having a fiber to polyurethane elastomer ratio of 100 to 65 is obtained. By impregnating a nonwoven fabric with polyurethane elastomer, a highly elastic nonwoven fabric layer (3) consisting of intertwined short fibers is created.
It is possible to prevent the thread slipping phenomenon that occurs when the surface fluff is pinched and pulled. Also, later, short fiber entangled nonwoven fabric layer (3
) When a solvent solution of polyurethane elastomer is applied to the surface to form a microporous layer of polyurethane, it prevents separation from the short fiber entangled nonwoven fabric layer (3) of the same layer, and improves the surface of the final product (artificial leather surface of polyurethane). This makes it possible to make the surface of the microporous layer smooth.

(4)' is a water-miscible organic solvent solution of polyurethane elastomer (trade name: Lisbon, manufactured by Dainippon Ink);
In this example, the solution is a polyurethane elastomer in dimethylformamide (solid content 23%). Instead of dimethylformamide, dioxane, methyl ethyl ketone, tetrahydrofuran may be used. The solution (4)' of the polyurethane elastomer in a water-miscible organic solvent is used to prepare the fiber substrate (1) impregnated with the polyurethane elastomer (6).
The short fibers are intertwined and applied to the surface of the nonwoven fabric layer (3). As a result, a microporous layer (7) having a thickness of 0.5 mm is obtained, as shown in the cross section of FIG. Next, the fiber base material (1
) is coagulated in a non-solvent (6)' mainly composed of water without dissolving the polyurethane elastomer.

Then, it is dried, subjected to surface treatment and hot embossing, and the long fiber entangled nonwoven fabric layer (2) made of spunbond nonwoven fabric on the back side is removed by a slicing process using a slicing machine. 1.2
Obtain mm-thick artificial leather. The fiber base material (1) had extremely good dimensional stability through each step of impregnation, coating, surface treatment, and hot embossing, and had virtually no shrinkage in the width direction due to tension in the direction of travel.

Comparative example supervisor.

In the example, when processed using a fiber base material (1) consisting only of a short fiber entangled nonwoven fabric layer (3) using a 1.5 denier 6 nylon spunbond nonwoven fabric, it showed remarkable elongation with respect to tensitan and water resistance. Among them, the elongation is the largest, and the width is 30%.
However, due to changes in the production of artificial leather, it was no longer possible to stably produce artificial leather.

Comparative Example 2 In the example, the short fiber entangled nonwoven fabric layer (3) that does not use the 1.5 denier 6 nylon spunbond nonwoven fabric has a polymerization degree of 1.
700, polyvinyl alcohol with a saponification degree of 98.5% is applied to the fiber at a weight ratio of 8% to prevent expansion and contraction, and then impregnated with a polyurethane elastomer solution (solid content 16%) and coagulated in water, and then the obtained nonwoven fabric An attempt was made to obtain a microporous layer by applying a polyurethane elastomer solution (solid content: 23%) to the material, but it was not possible to obtain a microporous layer with remarkable elongation during the solidification process and excellent dimensional stability.

(F) Effects of the Invention Therefore, according to the present invention, it is possible to provide an artificial leather having excellent dimensional stability while having value as an artificial leather.

[Brief explanation of drawings]

1 is an embodiment of the present invention, FIG. 2 is a sectional view of section A in FIG. 1, and FIG. 3 is a sectional view of section B in FIG. 1. (1)... Fiber base material, (2)... Long fiber entangled nonwoven fabric layer, (3)...
... Short fiber entangled nonwoven fabric layer, (4), (4)'...
... Water-miscible organic solvent solution of polyurethane elastomer, (5) ... Squeezing roll, (6), (6)' ... Non-solvent mainly composed of water, (7)...Microporous layer.

Claims (1)

[Claims] The intertwined short fiber layer is integrated with the intertwined long fiber layer to form a fiber base material, and a solution of polyurethane elastomer in a water-miscible organic solvent is filled into the voids of the fiber base material, and then in a non-solvent mainly containing water. Then, a water-miscible organic solvent solution of polyurethane elastomer is applied to the surface of the short fiber entangled body layer, which is then coagulated and dried in a water-based non-solvent to form a microporous layer. A method for producing artificial leather, characterized by removing a body layer.