JPH0291278A - Production of synthetic leather - Google Patents

Abstract

PURPOSE:To obtain a flexible natural leathery synthetic leather excellent in moisture permeability by forming a polyurethane resin layer containing a water- soluble natural high polymer substance on the surface of a substrate, dissolving and removing the above-mentioned natural high polymer substance using a hydrolytic enzyme. CONSTITUTION:For example, a polyurethane resin solution containing a water soluble high polymer substance 2 (e.g., starch or glue or gelatin) is applied to the creped surface of a creped mold release paper 1, dried by heating, superposed on a substrate 6 (e.g., nylon, polyester or cotton) and thermocompressed. The mold release paper 1 is subsequently peeled to provide a laminated body 9 having a polyurethane resin layer 5 containing the above-mentioned natural high polymer substance. The resultant laminated body 9 is then dipped in a warm water containing a hydrolytic enzyme for the afore-mentioned high polymer substance 2 to dissolve and remove the natural high polymer substance. Thereby, a flexible synthetic leather, improved in moisture and air permeability, excellent in drapeability, having the formed microcellular skin layer and resembling natural leather is obtained.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to synthetic leather and a method for producing the same.

[Conventional technology]

In recent years, instead of natural leather, artificial leather and synthetic leather, which are formed by laminating a synthetic resin elastic body such as polyurethane on a base material such as woven fabric or non-woven fabric, have become widely used. Various improvements have been made to make the appearance, texture, and feel of synthetic leather more similar to natural leather.

A method of adding natural leather powder to synthetic resin has been proposed as a method to bring the texture, portholes, etc. of artificial leather and synthetic leather closer to those of natural leather. Natural leather powder is added to a thermoplastic resin compound in a weight ratio of 70 to 30% based on the leather powder, and a blowing agent is further added to this and mixed, followed by heat rolling to form a foamed sheet. Artificial leather (Japanese Unexamined Patent Publication No. 10641/1983) and the like are known.

[Problem to be solved by the invention]

However, since the artificial leather described in JP-A No. 63-10641 is heat-rolled and foamed to form a sheet, a so-called skin layer is formed on the epidermis, and this skin layer allows natural leather powder to be The addition of this material impairs the natural leather-like feel, and also results in poor moisture permeability and air permeability. For this reason, it is necessary to slice and remove the skin layer, which complicates the manufacturing process, and because natural leather powder is added to the resin and foamed, the natural leather powder is dispersed throughout the artificial leather. Therefore, unless a large amount of natural leather powder is added, the surface feel cannot be sufficiently improved, and if a large amount of natural leather powder is added, although the surface feel can be improved, the strength of the entire leather decreases. However, it had contradictory drawbacks, such as making it impractical for practical use.

[Means to solve the problem]

The present invention solves the above-mentioned drawbacks of the prior art, improves appearance, texture,
The purpose of the present invention is to provide a method for producing synthetic leather that has excellent feel and physical properties such as moisture permeability and air permeability.

That is, the present invention provides the following steps: (1) After forming a polyurethane resin layer containing a water-soluble natural polymer substance on at least one side of a base material, the laminate is placed in hot water containing an enzyme that decomposes the water-soluble natural polymer substance. A method for producing synthetic leather, which comprises soaking to dissolve and remove a water-soluble natural polymer substance to form a porous skin layer.

(2) After coating a hydrophilic organic solvent solution of polyurethane resin on at least one side of the substrate, immerse it in water to remove the solvent and coagulate the polyurethane to form a microporous layer of polyurethane resin, and then form a microporous layer of polyurethane resin on the surface. After forming a polyurethane resin layer containing a water-soluble natural polymer substance, the laminate is immersed in hot water containing a degrading enzyme for the water-soluble natural polymer substance to dissolve and remove the water-soluble natural polymer substance. A method for producing synthetic leather, characterized by forming a porous skin layer.

(3) The method for producing synthetic leather according to claim 1 or 2, characterized in that the water-soluble natural polymer substance is dissolved and removed using a jet dyeing machine.

The main points are as follows.

〔Example] Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 shows an example of the method for producing synthetic leather of the present invention. First, for example, a skin layer-forming polyurethane resin containing a water-soluble natural polymer substance 2 (FIG. 2) is applied to the grained surface of a grained release paper L. After applying the solution to a uniform thickness using a doctor knife 3 or the like, it is dried in a heating oven 4 to form a polyurethane resin layer 5 containing a water-soluble natural polymer substance 2, and then layered with a base material 6. The mixture is heated by a heating roll 7 to bond them together under heat and then passed through a heating oven 8 to completely volatilize the remaining solvent, and then the release paper 1 is peeled off to contain the water-soluble natural polymer substance 2. A laminate 9 in which a polyurethane resin layer 5 is transferred and laminated onto a base material 6
get.

The base material 1 may be a woven fabric made of fibers such as nylon, polyester, cotton, or rayon alone or a blend of these fibers;
Nonwoven fabrics, knitted fabrics, etc. are used.

Water-soluble natural polymer substances 2 include starches such as potato starch, potato starch, wheat starch, kubioka starch, cornstarch, glue, gelatin, casein,
Examples include proteins such as collagen. It is preferable to use these water-soluble natural polymer substances 2 with a particle size of 30μ or less, particularly 20μ or less; if the particle size is too large, the polyurethane resin containing these water-soluble natural polymer substances 2 will not be uniform when applied. It becomes difficult to apply the product in a consistent manner, and streaks are more likely to occur on the surface. The amount of the water-soluble natural polymer substance 2 added to the polyurethane resin is preferably 100 to 20% by weight, particularly 70 to 30% by weight based on the resin. If the amount of the water-soluble natural polymer substance 2 added is too small, no improvement in moisture permeability or air permeability can be expected, and if it is too large, the moisture permeability or air permeability will be good, but the membrane strength will drop significantly.

As the polyurethane resin to which the water-soluble natural polymer substance 2 is added, any of polyester polyurethane, polyether polyurethane, polycaprolactone polyurethane, polycarbonate polyurethane, etc. can be used.

Next, the laminate 9 is immersed in hot water containing a degrading enzyme for the water-soluble natural polymer substance 2 contained in the polyurethane resin layer 5 to dissolve and remove the water-soluble natural polymer substance 2, thereby forming a third layer. A synthetic leather 12 having a skin layer 11 having micropores 10 as shown in the figure is obtained.

As the degrading enzyme, amylase is used when the water-soluble natural polymer substance 2 contained in the polyurethane resin layer 5 is starch, and protease is used when the water-soluble natural polymer substance 2 is a protein. . By containing these degrading enzymes in the hot water for dissolving water-soluble polymeric substances, the dissolution process of water-soluble natural polymeric substances can be carried out more efficiently at lower temperatures than when no degrading enzymes are included. This makes it possible to prevent deterioration of the polyurethane resin, shorten the time for dissolving and removing the water-soluble natural polymer substance, and improve the removal rate. The amount of these degrading enzymes added is preferably 0.01 to 5% by weight of the water-soluble natural polymer substance contained in the polyurethane resin of the sheet to be immersed. When dissolving and removing water-soluble natural polymer substance 2,
It is preferable to adjust the pl+ of the treatment solution to a range where the activity of the degrading enzyme is high.If the enzyme is amylase, the pH
In the case of protease, pH=5 to 7 is preferably set to pH=7 to 11. The water-soluble natural polymer substance 2 is dissolved and removed by dissolving and removing the laminate 9 in hot water of about 50 to 70'C.
It is preferable to soak for about 2 hours.

When the water-soluble natural polymeric substance 2 is dissolved and removed while being subjected to the rubbing treatment, the dissolution and removal rate is improved, and the softening treatment can be performed at the same time. This rubbing treatment is preferably carried out using a jet dyeing machine because it can be carried out well.

Note that the rubbing treatment may be performed in a separate step after dissolving the water-soluble natural polymer substance.

The above example shows the case where the polyurethane resin layer 5 containing the water-soluble natural polymer substance 2 is laminated and integrated with the base material l by heating lamination, but it may also be adhered to the base material l with an adhesive. In this case, the water-soluble natural polymer substance 2 is also contained in the adhesive. This is to ensure that the water-soluble natural polymer substance 2 contained in the polyurethane resin layer for forming the skin layer is efficiently (dissolved and removed) both from the front side and the back side of the laminate 9. As the adhesive, two-component polyurethane resins such as polyester polyurethane, polyether polyurethane, polycaprolactone polyurethane, and polycarbonate polyurethane can be used.

In the present invention, after applying a hydrophilic solvent solution (for example, DMF, etc.) of a polyurethane resin to at least one side of the base material 1, the polyurethane is solidified by immersing it in water to remove the solvent, and pores are formed by removing the solvent. After that, a polyurethane resin layer 5 containing a water-soluble natural polymer substance 2 is formed on the surface of the microporous N14 having a water-soluble natural polymer substance 2 in the same manner as described above. The polymer substance 2 can also be dissolved and removed in the same manner to produce synthetic leather as shown in FIG. 4, in which a skin layer 11 having micropores 10 is provided. By providing such a microporous layer 14, the flexibility of the synthetic leather is further improved and the synthetic leather has a feel similar to natural leather.

Further, a polyurethane resin layer containing a water-soluble natural polymer substance is coated on the surface of the skin layer 11 or the surface of the polyurethane resin layer 5 for forming the skin layer 11 by a gravure coating method, and then the water-soluble natural polymer substance is applied. It is also possible to obtain a synthetic leather as shown in FIG. 5 in which a surface treatment layer 15 having micropores 10 is provided by dissolving and removing the pores. Surface treatment layer 15
It is preferable to apply the polyurethane resin for forming the film so that the dry coating amount is about 1 to 5 g/rrf. As the polyurethane resin solution used to form this surface treatment layer 15, in addition to ordinary polyurethane resins, silicon-modified polyurethane resins, amino acid-modified polyurethane resins, polyamide-modified polyurethane resins, etc. are used. If a surface treatment layer 15 having micropores IO is further provided on the surface of the skin layer 11, the feel of the surface can be made more similar to that of natural leather.

In addition, in the present invention, for the purpose of coloring the epidermal layer 11, the epidermal layer 1
A coloring agent such as a pigment or dye can be added to the polyurethane resin layer 5 forming the polyurethane resin N5 or, if necessary, to the adhesive layer provided for the purpose of adhering the polyurethane resin N5. Furthermore, other additives such as various stabilizers and fillers may be added to the skin layer 11 if necessary.

Hereinafter, the present invention will be explained in more detail by giving specific examples.

Example 1 The surface of textured release paper contains 45% by weight of casein with an average particle size of 15μ, and the 100% modulus is 70kg/c.
+fl polyester polyurethane resin (Dainippon Ink: Crispon NB-6313) 19% DMF-M
An EK solution (containing 15 parts by weight of colorant per 100 parts by weight of polyurethane resin) was coated with a knife coater to a dry thickness of 20 μm and heated at 90″C for 1.
It was dried with hot air for 5 minutes to form a polyurethane resin layer.

Next, on the surface of this polyurethane resin layer, particles having an average particle size of 15 μm were coated.
40% MEK of two-wave type polyurethane adhesive (Dainippon Ink Co., Ltd.: Crisbon TA-465) with a 100% modulus of 20 kg/cIII containing 50% by weight of casein.
- After applying a toluene solution to a basis weight of 100 g/bottom and drying it with hot air at 90"C for 1.5 minutes,
It is laminated with a woolly nylon tricot L-W cloth (base material) with a thickness of 0.5 mm, and then heated and dried to harden the adhesive. After that, the release paper is peeled off, and the base material contains casein. A laminate was formed by transferring the polyurethane resin layer.

This laminate was dyed with Alcalase 2, a casein degrading enzyme, using a jet dyeing machine. pH containing 2% by weight of OT (Bacillus lichenylformis bacterial protease manufactured by Novo) =
The casein was dissolved and removed while being immersed in 50°C warm water of 8.0°C for 60 minutes and rubbed, forming a skin layer with micropores to obtain synthetic leather.

The resulting synthetic leather has a soft texture and drapability.
Moreover, it retained its wrinkles after being rubbed for a long period of time, was extremely flexible, and had an appearance and feel very similar to natural leather, making it suitable as a material for clothing. The moisture permeability of this synthetic leather (
According to JIS Z-0208) is 2870g/rd・2
4 hours, and the air permeability (according to JIS L-1096) was 0.5 cc/c++1·sec.

Furthermore, the removal rate of casein in the epidermal layer was 95%.

Example 2 A 11% DMF solution of a polyester polyurethane resin (manufactured by Dainippon Ink: Crisbon MP812NB) with a 100% modulus of 20 kg/c+IT was applied to the roughly brushed surface of a 0.4 mm thick acrylic nonwoven fabric (base material). is 600
g/rri, then desolvated in water at 20°C to solidify, dehydrated and dried under hot air at 130°C to form a base having a microporous layer with a thickness of 0.55 mm. I got the material.

On the other hand, the 100% modulus of paper containing 50% by weight of glue with an average particle size of 12μ on the surface of pattern 1 paper is 60k.
20% DMF-M of polyester polyurethane resin (Rezamin ME3614LP manufactured by Dainichiseika Chemical Co., Ltd.) of g/cnl
EK solution (containing 15 parts by weight of coloring agent per 100 parts by weight of polyurethane resin) was applied with a knife coater to a dry thickness of 25μ, dried with hot air at 10°C for 2 minutes, and coated with polyurethane resin.・After forming a urethane resin layer and thermocompression bonding at 140°C while heating the microporous layer surface of the base material with the microporous layer formed on the surface of this polyurethane resin layer, the release paper is peeled off to form the microporous layer. A laminate was obtained in which a polyurethane resin layer containing glue was transferred to the layer surface. This laminate is dyed using a jet dyeing machine using Enthiron SA (manufactured by Rakuto Kasei: bacterial protease of the genus Bacillus), which is a glue-degrading enzyme.
The material was immersed in warm water at 60° C. containing 1.5% by weight of P11 = 7.5 for 60 minutes and rubbed while dissolving and removing the glue, forming a skin layer with micropores to obtain synthetic leather.

The resulting synthetic leather has a soft texture and drapability.
Moreover, it retained its wrinkles after being rubbed for a long period of time, was extremely flexible, and had an appearance and feel very similar to natural leather, making it suitable as a material for clothing. The moisture permeability of this synthetic leather is 3650 g/% for 24 hours, and the air permeability is 0.
It was 7 cc/cla·sec. The removal rate of glue in the epidermal layer was 98%.

Example 3 A polyester polyurethane resin (manufactured by Dainichiseika Chemical Co., Ltd.: Rezamin C) with a 100% modulus of 25 kg/cffl was applied to the raised surface of a polynosic cloth (base material) with a thickness of 0.45 mra.
US-100) 10% DMF solution with a basis weight of 600
g/rrf, then desolvated in water at 20°C to solidify, then dehydrated and dried under hot air at 130°C to form a base material having a microporous layer with a thickness of 0.60a++. I got it.

On the other hand, on the surface of the textured release paper, 18% DMF of a polyester-based polyurethane resin (Rezamin ME3412LP, manufactured by Dainichiseika Chemical Co., Ltd.) with a 100% modulus of 40 kg/cd and containing 60% by weight of potato starch with an average particle size of 17 μm was applied.
- MEK solution (containing 20 parts by weight of coloring agent per 100 parts by weight of polyurethane resin) was applied with a knife coater to a dry thickness of 20μ, and dried with hot air at 90°C for 2 minutes, A polyurethane resin layer is formed, and the microporous layer surface of the base material on which the microporous layer is formed is thermocompressed at 145°C without heating, and the release paper is peeled off to form the microporous layer. A laminate was obtained in which a polyurethane resin layer containing potato starch was transferred to the layer surface. This laminate was dyed using a jet dyeing machine with a pH-5 dye containing 2% by weight of Enthiron FA (manufactured by Rakuto Kasei: Aspergillus amylase), which is a potato starch degrading enzyme.
, 5 in warm water at 60°C for 60 minutes, the potato starch was dissolved and removed while being rubbed, and a skin layer with micropores was formed to obtain synthetic leather.

The resulting synthetic leather has a soft texture and drapability.
Moreover, it retained its wrinkles after being rubbed for a long period of time, was extremely flexible, and had an appearance and feel very similar to natural leather, making it suitable as a material for clothing. The moisture permeability of this synthetic leather is 3790g/rrf・24 hours, and the air permeability is 0.
．． It was 7 cc/d·sec. Moreover, the removal rate of potato starch in the epidermal layer was 97%.

Comparative Example 1 Synthetic leather was obtained in the same manner as in Example 1, except that a solution containing no casein degrading enzyme was used as the treatment solution for dissolving and removing casein (rubbing treatment using a jet dyeing machine was also performed in the same manner). . The moisture permeability of the obtained synthetic leather is 1360g/rrr
・24 hours, air permeability is Q,'l cc/ci
・It was less than seconds. Furthermore, the removal rate of casein in the epidermal layer was 47%.

Comparative Example 2 Synthetic leather was obtained in the same manner as in Example 2, except that a treatment solution containing no glue-degrading enzyme was used for dissolving and removing glue (rubbing treatment using a jet dyeing machine was also performed in the same manner).
. The resulting synthetic leather had a moisture permeability of 1990 g/m·24 hours and an air permeability of 0.3 cc/CTM·sec or less. The removal rate of glue in the epidermal layer was 54%.

Comparative Example 3 Synthetic leather was obtained in the same manner as in Example 3, except that a solution containing no potato starch degrading enzyme was used as the treatment solution for dissolving and removing potato starch (rubbing treatment using a jet dyeing machine was also performed in the same manner) ). The moisture permeability of the obtained synthetic leather is 216
0g/rrf・24 hours, air permeability 0.3Cc/
The cI was 11 seconds or less.

Moreover, the removal rate of potato starch in the epidermal layer was 57%.

Comparative Example 4 Synthetic leather was obtained in the same manner as in Example 1, except that the polyurethane resin for forming the skin layer did not contain casein (rubbing treatment using a jet dyeing machine was also performed in the same manner).

). The moisture permeability of the obtained synthetic leather is 130g/rrr・2
The air permeability was Q, 2 cc/c-sec or less.

Comparative Example 5 Synthetic leather was obtained in the same manner as in Example 2 except that the polyurethane resin for forming the skin layer did not contain glue (rubbing treatment using a jet dyeing machine was also performed in the same manner).

). The resulting synthetic leather has a moisture permeability of 1260g/rrr.
It is 24 hours, and the air permeability is 0. It was less than 2cc/cffl·sec.

Comparative Example 6 Synthetic leather was obtained in the same manner as in Example 3, except that the polyurethane resin for forming the skin layer did not contain potato starch (the rolling treatment using a jet dyeing machine was also performed in the same manner). The moisture permeability of the obtained synthetic leather was 1370 g/bo for 24 hours,
The air permeability was 0.2 cc/C⋅sec or less.

〔Effect of the invention〕

As explained above, in the method of the present invention, after providing a polyurethane resin layer containing a water-soluble natural polymer substance on the surface of a base material, the water-soluble natural polymer substance in the polyurethane resin layer is
By adopting a method of dissolving and removing the water-soluble natural polymer substance in warm water containing degrading enzymes to form a porous skin layer, it has excellent moisture permeability and air permeability, and is soft to the touch and drapey. Synthetic leather can be obtained that has excellent flexibility, has excellent elasticity, and has an appearance and feel very similar to natural leather. Further, the flexibility can be further improved by providing a microporous layer formed by a wet method between the skin layer and the base material. Further, according to the method of the present invention, the water-soluble natural polymer substance in the polyurethane resin layer for forming the skin layer can be efficiently dissolved and removed. Furthermore, if a jet dyeing machine is used to dissolve and remove the water-soluble natural polymeric substance, it is possible to perform the removal of the water-soluble natural polymeric substance and the softening treatment at the same time.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, FIG. 1 is an explanatory diagram showing an example of the manufacturing method of the present invention, FIG. 2 is a cross-sectional view taken along the vertical line in FIG. A vertical cross-sectional view showing an example of the synthetic leather obtained, and FIGS. 4 and 5 are longitudinal cross-sectional views showing different aspects of the synthetic leather obtained by the present invention, respectively. 2... Water-soluble natural polymer substance 5... Polyurethane resin layer 6... Base material 10... Fine pores 11... Skin layer 12... Synthetic leather 13... Holes 14... Microporous layer Figure 1 Figure 2 Figure 6: Base material

Claims (3)

[Claims] (1) After forming a polyurethane resin layer containing a water-soluble natural polymer substance on at least one side of the base material, the laminate is immersed in hot water containing a degrading enzyme for the water-soluble natural polymer substance to dissolve the water-soluble natural polymer substance. A method for producing synthetic leather, characterized by forming a porous skin layer by dissolving and removing natural polymeric substances. (2) After coating a hydrophilic organic solvent solution of polyurethane resin on at least one side of the substrate, immerse it in water to remove the solvent and coagulate the polyurethane to form a microporous layer of polyurethane resin, and then form a microporous layer of polyurethane resin on the surface. After forming a polyurethane resin layer containing a water-soluble natural polymer substance, the laminate is immersed in hot water containing a degrading enzyme for the water-soluble natural polymer substance to dissolve and remove the water-soluble natural polymer substance. A method for producing synthetic leather, characterized by forming a porous skin layer. (3) The method for producing synthetic leather according to claim 1 or 2, characterized in that the water-soluble natural polymer substance is dissolved and removed using a jet dyeing machine.