JPS6335891A - Production of synthetic leather - Google Patents

Abstract

PURPOSE:To obtain synthetic leather having lightweight and flexible expanded layer by dry method, by using a foamable resin composition containing thermally expanding microcapsules instead of a blowing agent and foaming the composition under heating. CONSTITUTION:A foamable resin composition containing a resin such as polyvinyl chloride paste resin, urethane resin, acrylic resin, etc., and thermally expanding microcapsules having 5-50mum average particle diameter is applied to release paper, dried and heated so that the shell wall of the microcapsules is heated and softened and a low-boiling compound in the interior is thermally expanded. Then the composition is cooled and the shell wall is recoagulated to form a uniform expanded layer consisting of fine closed cells. An adhesive is applied to the expanded layer, stuck to fabric backing and release paper is removed to give synthetic layer having a lightweight and flexible expanded layer which possesses 30-100mum expanded cell diameter and 80-90% cell density (ratio of area of expanded cell in section of expanded structure).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing synthetic leather, and more particularly, to a method for producing synthetic leather having a lightweight and flexible foam layer by a so-called dry method.

Conventionally, wet methods and dry methods are known as methods for producing synthetic leather. Among these, the dry method involves first applying and drying a resin to form a skin layer on a release paper mound, then applying a resin composition containing a resin and a foaming agent thereon, and heating it.
This is a manufacturing method in which foam cells are formed using gas generated by decomposition of a foaming agent to form a foam layer, a base fabric is bonded with an adhesive, and a release paper is peeled off. For example, when polyvinyl chloride paste resin is used as the resin forming the foam layer, 60 to 100 parts by weight of a plasticizer and 2 to 5 parts by weight of a foaming agent such as Azocicabonamide are used for 100 parts by weight of the resin. The foamable resin composition containing the above is heated to form a foam layer.

However, conventionally, it has been difficult to obtain synthetic leather having a lightweight and flexible foam layer by this dry method. In particular, when polyvinyl chloride paste resin is used as the resin, its specific gravity is high, so the resulting synthetic leather is heavy, and as mentioned above, it is necessary to use a large amount of plasticizer, resulting in so-called bloating. It has a solid feel and appearance.

On the other hand, when increasing the porosity of the foam cells in order to reduce the weight of the foam layer, gas escape occurs during heating and foaming of the foaming agent, causing the foam layer to sag.

Therefore, as a result of intensive research in order to solve the above-mentioned problems with conventional synthetic leather, the inventors of the present invention developed a thermally expandable foaming agent in place of the conventional foaming agent. We have discovered that by using a foamable resin composition containing microcapsules and heating and foaming it, it is possible to form a lightweight and flexible foam layer that is equivalent to the wet method even in a dry method, and has developed the present invention. This is what we have come to.

A method for manufacturing synthetic leather according to the present invention is a method for manufacturing synthetic leather in which a resin foam layer is laminated on a base fabric, in which resin and an average particle size of 5 to 50 μm are used. The method is characterized in that a foamable resin composition containing thermally expandable microcapsules is applied onto a base fabric and heated to form a foam layer.

In the present invention, as the resin, for example, polyvinyl chloride paste resin, urethane resin, acrylic resin, etc. can be used. When using polyvinyl chloride paste resin as the resin, the foamable resin composition contains 50 to 100 parts by weight of a plasticizer and 10 to 10 parts by weight of thermally expandable microcapsules based on 100 parts by weight of the polyvinyl chloride paste resin.
Contains 30 parts by weight and an appropriate amount of stabilizer.

As the plasticizer, for example, a phthalate plasticizer is preferably used. Specific examples of such plasticizers include dibutyl phthalate and dioctyl phthalate. Epoxy plasticizers may also be used if necessary. As the stabilizer, for example, a Ba-Zn stabilizer is suitable, and usually a polyvinyl chloride base resin.
1 to 3 parts by weight per 00 parts by weight.

The foamable resin composition containing polyvinyl chloride paste resin as the resin may contain appropriate amounts of ordinary compounding agents such as fillers, antioxidants, thickeners, and colorants, as necessary.

In addition, a foamable resin composition containing a urethane resin or an acrylic resin as a resin contains 10 to 30 parts by weight of thermally expandable buiclocapsules per 100 parts by weight of a resin solution containing 10 to 30 parts by weight of the resin. do. In this case as well, the foamable resin composition may contain appropriate amounts of ordinary compounding agents such as fillers, antioxidants, thickeners, and colorants, if necessary.

The thermally expandable microcapsules used in the present invention are:
It refers to microcapsules with a shell wall made of thermoplastic resin and containing a low-boiling organic compound such as a hydrocarbon such as butane inside. Various types of shells with different heat softening temperatures are commercially available. In the present invention, thermally expandable microcapsules having an average particle size of 5 to 50 μm are particularly preferably used. Furthermore, when the resin used is polyvinyl chloride paste resin, it is preferable that the heat softening temperature of the shell wall is 100 to 150°C.

According to the method of the present invention, in the synthetic leather manufacturing process,
When a foamable resin composition containing such thermally expandable microcapsules is applied onto a release paper, dried, and heated, the shell wall of the thermally expandable microcapsules is thermally softened, and the low boiling point compound inside expands. Then, during the cooling process, the shell wall re-solidifies to form a homogeneous foam layer consisting of fine closed cells.

For example, according to the dry method using conventional polyvinyl chloride paste resin as the resin, the gas generated by decomposing the blowing agent is encapsulated within the resin matrix.
Form a foam layer. Therefore, it is necessary to use a relatively large amount of resin as a matrix, so as mentioned above, the density of the foam layer is usually 0.3 to 0.
．． 5 g 7 cm 3 , which is significantly larger than the density of the foamed layer obtained by the wet method, which is 0.1 to 0.3 g/cm 3 .

However, according to the method of the present invention, by heating the foamable resin composition, the shell walls of the thermally expandable microcapsules soften and expand, fuse together, and solidify during the cooling process. , since a foamed layer is formed, the amount of resin is sufficient as a binder to bond the expanded microcapsules to each other. Therefore, according to the method of the present invention, compared to the conventional dry method, The amount of resin can be significantly reduced. Furthermore, since the foamed cells are formed by expanded microcapsules, such foamed cells are independent, finely spherical, round, and homogeneous;
As a result, it is possible to obtain a lightweight foam layer, which has conventionally been difficult to obtain by dry methods.

According to the present invention, the normally 11 foam cell diameter is substantially 30 to 30.
100. It is possible to obtain synthetic leather having a lightweight and flexible foam layer with Ijm and a cell density of 80 to 90%. Here, the cell density refers to the ratio of the area occupied by foam cells in the cross section of the foam structure. In particular, when polyvinyl chloride-based resin is used as the resin, it is possible to obtain a foamed layer with a density of 0.30 to 0.37 g (7 cm), and furthermore, as the amount of resin is reduced, the amount of plasticizer required is also small. Therefore, the foam layer does not have the above-mentioned so-called bubbly.

Also, as described above, according to the method of the present invention, the amount of resin used can be significantly reduced compared to the production of synthetic leather using the conventional dry method. It is possible to produce synthetic leather with a lightweight foam layer, which has been difficult to produce. In addition, the foamed cells obtained by the method of the present invention have an independent fine spherical shape and are homogeneous, so they have excellent texture.

In particular, in the method of the present invention, when polyvinyl chloride-based resin is used as the resin, it is possible to obtain a lightweight foam layer with a density of 0.1 to 0.3 g 7 cm3, which is equivalent to the wet method. Moreover, as the amount of resin used decreases, the amount of plasticizer required also decreases, so the foamed layer does not have a so-called bulky feel.

Husband Charcoal Synthetic leather was manufactured using the following formulation; 7.

Note that the number of parts indicates parts by weight.

Polyvinyl chloride base resin (degree of polymerization 1650) Ioo part Dioctyl phthalate 80 parts Ba-Zn stabilizer FL54 (manufactured by Adeka Argus Chemical ■)
Two-part thermally expandable microcapsule F80D
(Matsumoto Yushi Pharmaceutical side type, shell wall softening temperature 140 to 145°C) Synthetic leather was produced using a composition consisting of 20 parts thickener (manufactured by Shiraishi Kogyo ■) and 4 parts.

A polyurethane solution (Dainichisei Kashuo, ■/Zamine 2825LP) was applied onto the release paper and dried to form a polyurethane film with a thickness of 30 μm. The above-mentioned polychlorinated Bursol compound was applied on top of this at a rate of 4008/m'' and heated and foamed in a hot air oven at 170°C for 1 minute. After cooling, the foam layer was coated with polyurethane. Apply adhesive side (Dainichiseika α Rock, 17 Zamin UD603) at a rate of 40 g/m2, immediately paste the raised side of the raised fabric on top, pressurize, and heat dry at 120°C for 2 minutes. After cooling and aging at 40°C for 2 days, the release paper was peeled off to obtain synthetic leather with a thickness of 1 and 2 mm.

The obtained synthetic leather has a foam cell diameter of 70 μm and a cell density of 8.
0%, the density of the foam layer was 0.13 g/cm1, it was extremely lightweight and flexible, had fine wrinkles found in natural leather, and had an excellent texture.

Comparative Example 1 Polyvinyl chloride base resin (degree of polymerization 1650) 100
Part dioctyl phthalate 80 parts Ba
-Zn stabilizer PL54 2 parts Foaming agent (Azosicabonamide) 3 parts Cell conditioner
1 part thickener
Synthetic leather with a thickness of 1.2H was produced in the same manner as in Example 1, except that a composition consisting of 4 parts was used.

The obtained synthetic leather had a foam cell diameter of 160 μm, a cell density of 85%, and a foam layer density of 0.37 g/cm3,
It was heavy, hard, and had large wrinkles.

Comparative example polyurethane solution 100 parts blowing agent (
Azodicarbonamide) 5-part crosslinking agent
2-part foam stabilizer
Synthetic leather with a thickness of 1.2 cm was produced in the same manner as in the example except that a mixture consisting of 1 part of polyvinyl chloride sol was used in place of the polyvinyl chloride sol and the heating and foaming temperature was 140°C.

The obtained synthetic leather had a foam cell diameter of 210 μm, a cell density of 80%, and a foam layer density of 0.41 g/cts, and was heavy, hard, and had large wrinkles.

Claims (4)

[Claims] (1) In a method for producing synthetic leather in which a resin foam layer and a skin layer are laminated on a base fabric, a resin and an average particle size of 5 to 5
A method for producing synthetic leather, which comprises heating a foamable resin composition containing thermally expandable microcapsules of 0 μm to form a foam layer. (2) In the foam layer, the foam cell diameter is 30 to 100 μm
The method for producing synthetic leather according to claim 1, wherein the synthetic leather has a cell density of 80 to 90%. (3) The method for producing synthetic leather according to claim 1, wherein the resin is polyvinyl chloride paste resin, urethane resin, or acrylic resin. (4) Using a foamable resin composition containing polyvinyl chloride paste resin as a resin, the density is 0.1 to 0.3 g/c.
The method for producing synthetic leather according to claim 1, characterized in that a foamed layer of m^3 is formed.