JPH086259B2 - Synthetic leather manufacturing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing synthetic leather, and more specifically, to a synthetic leather which has a mechanical foaming layer, has excellent interlayer strength, and is lightweight and flexible, and such synthetic leather. Manufacturing method.

2. Description of the Related Art Conventionally, a mechanical foaming method has been known as a typical method for producing synthetic leather. In this mechanical foaming method, a resin solution such as polyurethane is mechanically stirred to form minute air bubbles in the solution, and the mechanically foamed resin solution does not have knitted fabric, woven fabric, or the like. After applying on the base cloth,
The resin is cured, and then a skin layer is adhered onto the resin with, for example, a urethane resin to produce synthetic leather.

The synthetic leather obtained by such a method is very lightweight and flexible, but since the foam layer does not include any reinforcing means, its cohesive failure strength is only 0.8 to 1.0 kg / cm.
However, since the interlayer strength is extremely small, the synthetic leather easily breaks in this foamed layer, and thus it is difficult to use it, for example, as a cover for sports shoes. Further, when the synthetic leather is bent, the foam layer is too soft, so that large creases are likely to occur in the skin layer.

Problems to be Solved by the Invention Therefore, as a result of intensive studies to solve the above-mentioned problems in the conventional synthetic leather including a mechanical foam layer, the present inventors have used a raised fabric as a base fabric, and The foamed resin solution is forcibly impregnated and cured to form a foamed layer containing naps, and in this way, the mechanical foamed layer is reinforced with naps to provide a lightweight and flexible property. The inventors of the present invention have found that it is possible to obtain a synthetic leather having an increased interlaminar strength while it is held.

Means for Solving Problems A synthetic leather production method according to the present invention is a synthetic leather production method in which a resin foam layer and a skin layer are formed on a base cloth, and a resin mechanically foamed on a raised cloth is used. The composition is characterized in that after the composition is applied, suction is applied from under the raised fabric to forcefully impregnate the raised fabric with the resin composition, and then the resin is cured to form a resin foam layer.

The napped cloth used as the base cloth in the present invention preferably has naps with a length of 400 to 1100 μm, and according to the present invention, the nap is formed up to the original twisted yarn layer of the napped cloth to form a mechanical foam layer. Let In general, when a mechanically foamed resin solution is applied onto a napped cloth, the resin solution only forms a layer on the napped layer and cannot be impregnated into the napped cloth so as to include the nap. . However, according to the present invention, after the mechanically foamed resin solution is applied to the napped cloth, the resin solution is impregnated to the original twisted yarn layer of the napped cloth by sucking from the non-raised surface, that is, the back surface. Can be made. In this way, by impregnating the raised fabric containing the raised fabric with the mechanically foamed resin solution, and then curing the resin,
It is possible to form a mechanically foamed layer including raised fibers up to the original twisted yarn layer of the raised fabric.

After that, the surface of the foamed layer is smoothed by an appropriate means such as buffing, and the skin layer is adhered onto the foamed layer via an adhesive to obtain the synthetic leather of the present invention.

FIG. 1 shows a cross-sectional view of the synthetic leather according to the present invention obtained in this manner, in which a raised fabric 2 having raised fabric 1 is used as a base fabric to form a mechanical foam layer 4 including raised fabrics up to the original twisted yarn layer 3. This foam layer is bonded to the skin layer 6 via the adhesive layer 5. Although not particularly limited, in the synthetic leather thus formed, the thickness of the original twisted yarn layer of the raised fabric is about 400 μm and the thickness of the mechanical foam layer is 700 μm.
About μm, both the adhesive layer thickness and the skin layer thickness
It is preferably about 20 to 30 μm.

In the present invention, as the resin forming the mechanical foam layer, a urethane resin or an acrylate copolymer is particularly preferably used, but in such a case, the mechanical expansion ratio of the resin solution is 1.7 to 4.5 times, particularly, The range of 2 to 4 times is preferable. When the expansion ratio is less than 1.5 times, the mechanical strength of the foam layer is large, but the specific gravity is large, not only lacking in lightness, but also the foam layer is too hard,
On the other hand, when it is more than 5.0 times, it is very lightweight, but the interlayer strength of the foamed layer formed is hardly improved as compared with the case of using a conventional knitted fabric or the like as the base fabric.

Effects of the Invention As described above, according to the synthetic leather of the present invention, the napped fabric is used as the base fabric, and the mechanical foam layer is formed so as to include the nap. Therefore, the foam layer is formed by reinforcing and hardening the nap. Generally, it has an interlayer strength of 1.5 kg / cm or more, and yet retains the lightness and flexibility of the mechanical foam layer.

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

Example 1 The following composition (parts indicate parts by weight): Urethane resin emulsion (anion type, S4040N manufactured by Hodogaya Chemical Co., Ltd. 100 parts) Water-soluble melamine resin (O manufactured by Hodogaya Chemical Co., Ltd.) 8 parts Water-soluble melamine resin (P from Hodogaya Chemical Co., Ltd.) 6 parts Foam stabilizer (DF18 from Hodogaya Chemical Co., Ltd.) 6 parts Thickener (LV30 from Hodogaya Chemical Co., Ltd.) 2 parts The resulting mixture was mechanically stirred with an electric whisk until the foaming ratio became 4 times.

This mechanically foamed resin mixture is applied to a napped cloth with a knife coater, suctioned from the back side to forcibly impregnate the napped cloth with the mixture, and then dried by heating at a temperature of 80 ° C for 2 minutes. Then, the resin was further heated at a temperature of 135 ° C. for 2 minutes to crosslink and cure the resin to form a resin foam layer. Then, the surface of this foam layer was buffed to be smooth.

Separately, an appropriately colored urethane resin (Resamine 2825LP manufactured by Dainippon Ink and Chemicals, Inc.) was applied on a release paper to a thickness of 10 μm by a reverse coater and dried by heating at 100 ° C. for 2 minutes. 20 μm of urethane resin adhesive (Crisbon 4090 manufactured by Dainippon Ink and Chemicals, Inc.) on top
It was applied to a thickness and heated at 120 ° C for 1 minute.

The adhesive-coated surface of this release paper was superposed on the buffed foamed layer, pressed and cooled, and then the release paper was peeled off to obtain a synthetic leather.

The synthetic leather thus obtained has a cell diameter of 10 to 30 μm,
Cell number density 100000 to 150,000 cells / cm ² , specific gravity 0.30 to 0.32 g / cm
^3. Bending flexibility (cantilever) 7.0 cm, JIS A hardness 55 degrees, light weight and flexibility, and resin foam layer interlayer strength of 1.5 to 1.7 kg / cm. Compared with the interlayer strength of the foam layer, it is significantly improved.

Example 2 The following composition (parts indicate parts by weight): Acrylic ester copolymer (Bonn Coat AF615 manufactured by Dainippon Ink and Chemicals, Inc.) 100 parts Melamine resin (manufactured by Hodogaya Chemical Co., Ltd.) 5 parts Cross-linking agent (Permastat manufactured by Dainippon Ink and Chemicals, Inc.)
CR5) A mixture consisting of 2 parts and 1 part of 28% ammonia water was mechanically stirred by an electric whisk until the expansion ratio became 4 times.

The foamed resin composition mechanically foamed is applied onto a napped cloth with a knife coater, sucked from the back side to forcefully impregnate the napped cloth with the composition, and then heated at a temperature of 100 ° C. for 5 minutes. The resin was dried and further heated at a temperature of 140 ° C. for 5 minutes to crosslink and cure the resin to form a resin foam layer. Then, the surface of this foam layer was buffed to be smooth.

Separately, an appropriately colored urethane resin (Resamine 2825LP manufactured by Dainippon Ink and Chemicals, Inc.) was applied on a release paper with a thickness of 10 μm by a reverse coater, and dried by heating at 100 ° C. for 2 minutes, 20 μm of urethane resin adhesive (Crisbon 4090 manufactured by Dainippon Ink and Chemicals, Inc.) on top
It was applied to a thickness and heated at 120 ° C for 1 minute.

The adhesive-coated surface of this release paper was superposed on the buffed foamed layer, pressed and cooled, and then the release paper was peeled off to obtain a synthetic leather.

The synthetic leather thus obtained has a cell diameter of 5 to 10 μm,
Cell number density 100000 to 150,000 cells / cm ² , specific gravity 0.32 to 0.35 g / cm
³ , lightness and flexibility of 7.0 cm, JIS A hardness of 50 degrees, light and flexible, and the interlayer strength of the resin foam layer is 1.5 to 2.0 kg / cm
However, it is remarkably improved as compared with the interlayer strength of the mechanical foam layer in the conventional synthetic leather.

Comparative Example The same formulation as in Example 1 was mechanically agitated with an electric whisk until the expansion ratio was 4 times.

This vaporized and foamed resin composition is applied on a knitted fabric with a knife coater, heated and dried at a temperature of 80 ° C for 2 minutes, and further heated at a temperature of 135 ° C for 2 minutes to crosslink and cure the resin. Then, the resin foam layer was formed. Then, the surface of this foam layer was buffed to be smooth.

Separately, a properly colored urethane resin (Resamine 2825LP manufactured by Dainippon Ink and Chemicals, Inc.) was applied on a release paper with a thickness of 10 μm by a reverse coater, and dried by heating at 100 ° C. for 2 minutes. 20 μm of urethane resin adhesive (Crisbon 4090 manufactured by Dainippon Ink and Chemicals, Inc.) on top
It was applied to a thickness and heated at 120 ° C for 1 minute.

The release paper was superposed on the buffing foamed layer with the adhesive-coated surface, pressed and cooled, and then the release paper was peeled off to obtain a synthetic leather.

The synthetic leather thus obtained has a cell diameter of 10 to 30 μm,
Cell number density 100000 to 150,000 cells / cm ² , specific gravity 0.25 to 0.27 g / cm
³ , lightness and flexibility of 7.0 cm and JIS A hardness of 45 degrees, but the interlayer strength of the resin foam layer was only 0.8 to 1.0 kg / c.
It was m.

Example 3 A synthetic leather was produced in the same manner as in Example 1 except that the same resin composition as in Example 1 was used and the expansion ratio was changed. These properties are shown in Table 1.

When the expansion ratio is set to 1.5 times, the resulting synthetic leather has too large a specific gravity, is not lightweight, and the foam layer is too hard. On the other hand, when the expansion ratio is 5.0, it is very lightweight, but the interlayer strength of the foam layer is too small.

[Brief description of drawings]

FIG. 1 shows a sectional view of a synthetic leather according to the present invention. 1 ... Brushed, 2 ... Raised cloth, 3 ... Original twisted yarn layer, 4 ... Mechanical foam layer, 5 ... Adhesive layer, 6 ... Skin layer.

Claims (1)

[Claims] 1. A method for producing synthetic leather in which a resin foam layer and a skin layer are formed on a base cloth, after applying a mechanically foamed resin composition onto a raised cloth, and then from below the raised cloth. A method for producing synthetic leather, which comprises sucking and forcibly impregnating a raised fabric with the above-mentioned resin composition, and then curing the resin to form a resin foam layer.