JPH04163377A - Production of synthetic leather - Google Patents

Abstract

PURPOSE:To obtain a synthetic leather excellent in moisture permeability and absorptivity and shrink resistance by laminating and integrating the surface of a substrate or a substrate layer with a polyurethane surface layer containing beta-chitin dispersed therein. CONSTITUTION:An ester-based polyurethane liquid obtained by dispersing readily dispersible beta-chitin excellent in physical properties in dimethylformamide and mixing the resultant beta-chitin suspension therewith is applied to the surface of a substrate composed of a woven or knit fabric such as synthetic or natural fiber or a substrate layer prepared by applying a polyurethane thereto, wet coagulating the polyurethane and forming a microcellular layer of the polyurethane according to a transfer or direct gravure coating method, etc. Thereby, the objective laminated unit having the polyurethane layer containing the beta-chitin homogeneously dispersed therein at a high concentration is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing synthetic leather, and more particularly to a method for producing synthetic leather having a polyurethane surface layer in which β-chitin is dispersed.

[Prior Art] Conventionally, wear materials are known in which a microporous polyurethane membrane is coated with a composite layer of polyurethane in which chitin is dispersed, in order to impart high moisture permeability and antibacterial properties.

However, the chitin conventionally used is α-chitin isolated from the exoskeletons of crustaceans and insects, especially crab carapaces. This α-chitin is difficult to fibrillate even when subjected to stirring or freezing/thawing treatment, and a gel-like substance cannot be obtained. In order to prepare this α-chitin suspension, it is necessary to dry-pulverize it in advance, which takes time and complicates the process.

Furthermore, the resulting α-chitin molded product has the disadvantage of low strength, low elongation, etc.

On the other hand, β-chitin separated from the squid carapace or soft carapace has a high affinity for water and swells easily, so it is easily fibrillated and eventually forms a gel. Furthermore, the obtained β-kijin molded product has excellent physical properties such as strength, elongation, and folding durability (see JP-A-1-198601 and JP-A-2-124903). Further β
- Chitin can be dispersed in an organic solvent such as dimethylformamide to obtain a uniform suspension, and this suspension can be used as it is for the production of synthetic leather.

[Invention or problem to be solved]

By using β-chitin, which is easy to disperse and has low physical properties, in place of the conventional α-chitin, the inventor of the tree can easily obtain a highly concentrated and more uniform chitin suspension, and can also produce synthetic leather. The inventors have discovered that synthetic leather can be easily produced, has excellent moisture permeability, hygroscopicity and drapability, and is free from rubber-like properties, leading to the present invention.

[Means to solve the problem]

The present invention is a synthetic leather manufacturing method in which a polyurethane surface layer in which β-chitin is dispersed is laminated and integrated on the surface of a base material or a base material layer.

As the base material in the present invention, woven fabrics, knitted fabrics, nonwoven fabrics, etc. made of fibers such as nylon, polyester, cotton, and rayon alone or blended fibers thereof may be used, and may be subjected to a napping treatment if necessary. The base material layer is a wet microporous layer of polyurethane laminated on the surface of the base material. After applying DMF (hereinafter referred to as DMF), the polyurethane is formed by immersing it in water to remove the solvent and coagulating the polyurethane.

The polyurethane layer in which β-chitin is dispersed is formed by a transfer method or a direct gravure coating method using a polyurethane solution containing a β-chitin suspension previously dispersed in an organic solvent (for example, DMF, etc.). It is laminated and integrated on the surface of the material or base material layer.

The polyurethane constituting the surface layer is appropriately selected from polyester polyurethane, polyether polyurethane, polycaprolactone polyurethane, polycarbonate polyurethane, and the like. The amount of β-chitin added is 1 to 100% by weight, preferably 5 to 50% by weight, based on the amount of polyurethane. If the amount of β-chitin added is too large, moisture permeability, hygroscopicity, and drapability will be good;
The film strength decreases, and if it is too low, no improvement in moisture permeability, hygroscopicity, or drapability can be expected, resulting in a rubber-like appearance.

When laminating and integrating by a transfer method, a polyurethane solution in which β-chitin is dispersed is applied to a release paper to a uniform thickness using a doctor knife or the like, and then dried to form a polyurethane surface layer, and then the base material or It is produced by adhering to the surface of the base material layer using an adhesive or by laminating them into one piece by a heating lamination method or the like, and finally peeling off the release paper. If necessary, a surface treatment layer may be further provided on the surface of the obtained surface layer.

As the adhesive, two-component polyurethanes such as polyester polyurethane, polyether polyurethane, polycaprolactone polyurethane, and polycarbonate polyurethane can be used.

In addition, in the heat lamination method, a polyurethane coating film with a low heat softening temperature may be formed on a polyurethane coating film in which β-chitin is dispersed, and then it may be laminated and integrated with the surface of the base material or base material layer. Further, in order to color the surface layer, a coloring agent can be added to the surface layer or the adhesive layer. If necessary, stabilizers, fillers and other additives may be added to the surface layer.

In the present invention, a polyurethane surface layer in which β-chitin is dispersed can be provided on both the front and back sides of the base material or base material layer, and the laminate after peeling off the release paper is rubbed using a jet dyeing machine or the like. Processing may be performed.

The synthetic leather produced by the method of the present invention has excellent moisture permeability and absorbency, does not have a rubber-like feel, has a soft texture and drapability, and retains wrinkles after being rubbed for a long period of time, so it has excellent flexibility. It is suitable as an excellent material for clothing.

[Effect]

β, which is easy to disperse and has excellent physical properties, in place of the conventional α-chitin
- By using chitin, a highly concentrated and more uniform chitin suspension can be easily obtained.

Furthermore, since it can be dispersed in an organic solvent such as DMF to obtain a uniform suspension, it can be used as is for the production of synthetic leather.

Therefore, the production of synthetic leather becomes easier, and β-chitin can be dispersed more uniformly at a higher concentration in the polyurethane surface layer, so that the performance of the resulting synthetic leather can be further improved.

The present invention will be explained below with reference to Examples.

Example 1 Polyester polyurethane (
Rezamin CuS300, manufactured by Dainichiseika Co., Ltd.) 10 parts by weight and D
A composition consisting of 90 parts by weight of MF was applied in an amount of 900 g/%, formed into a film by a wet coagulation method, and dried to obtain a base material layer having a wet microporous layer.

On the other hand, β-chitin isolated from squid carapace (manufactured by Nippon Suisan Co., Ltd.) 3
Mix parts by weight and 97 parts by weight of DMF, and mix with a ball mill to combine 2 parts by weight.
After dispersing for 4 hours, a β-chitin suspension was obtained. Next, 1.00 parts by weight of the above β-chitin suspension was mixed with 100 parts by weight of a DMF solution (concentration 30% by weight) of polyester polyurethane (Lethermin ME3432LP, manufactured by Dainichiseika Kaisha, Ltd.), and 50 g of the suspension was placed on release paper. The polyurethane layer was coated with a knife coating in an amount of /rrr and dried at 80°C to form a polyurethane layer with a thickness of 10μ.

On top of this, polyester polyurethane (Lethermin M E
A mixed solution of DMF and methyl ethyl) containing 15% by weight of 3432 LP (manufactured by Dainichiseika Chemical Co., Ltd.) and 10% by weight of color pigment was applied at a coating weight of 80 g/nf, and 90 g/nf was applied.
It was dried to form a coating film with a thickness of 20 μm.

After bonding the microporous layer surface of the following base material layer to this coating film-A by thermocompression bonding at 20°C without heating, the release paper was peeled off.
The anti-stretch cloth was then peeled off to obtain a laminate having a polyurethane surface layer in which β-chitin was dispersed on the surface of the base layer.

This laminate was subjected to a rolling treatment using a jet dyeing machine, and then dried using a tumble drier to obtain a synthetic leather that was moisture permeable, absorbent, and drapable, free from sagging, scratches, and likeness.

The measurement results are shown in Table 1 along with the measurement method.

Comparative Example 1 Synthetic leather was obtained in the same manner as in Example 1, except that α-chitin separated from crab shell (manufactured by Kyowa Yushi Co., Ltd.) was used instead of β-chitin in Example 1.

The measurement results are shown in Table 1.

= 7- Table 1 From the results in Table 1, it can be seen that the example using β-chitin had better moisture permeability and moisture absorption, and wrinkle resistance than Comparative Example 1 using α-chitin. So, 65-70% of the value measured on the skin.
A value close to that of leather was obtained, and the texture was closer to that of leather.

Example 2 In the same manner as in Example, a polyurethane layer containing 10% β-chitin by weight was formed on a release paper. To the I-, 35 parts by weight of polyether polyurethane (Crisbon C4010, manufactured by Dainippon Ink & Chemicals Co., Ltd.), 5 parts by weight of an isocyanate crosslinking agent (Chrisbon NX, manufactured by Dainippon Ink & Chemicals Co., Ltd.), 30 parts by weight of DMF, and 30 parts by weight of toluene. 100g/nf of the composition was applied, and
Dry at °C for 50 seconds.

This coating: Model 1- is made of polyester ♀ya fiber and rayon fiber or 65/3! The raised surfaces obtained by raising the fabric made of the spun blended in step i are laminated and heated at 60°C14
After the adhesive layer was reacted and assimilated for 8 hours, the release paper was peeled off and a rubbing treatment was performed to obtain synthetic leather.

As in Example 1, the obtained synthetic leather had moisture permeability, hygroscopicity, and drapability, and was free from creasing, gluing, and likeness.

〔Effect of the invention〕

By using β-chitin, which is easily dispersed and has superior physical properties, in place of the conventional α-chitin, a chitin suspension with high concentration and uniformity can be easily obtained, and synthetic leather can be manufactured easily. Furthermore, β- is added to the polyurethane surface layer.
Since chitin can be dispersed in a higher concentration and more uniformly, the performance of the resulting synthetic leather can be improved across layers.

Patent applicant: Toyo Cross Co., Ltd. IO-

Claims (1)

[Claims] A method for producing synthetic leather, which comprises laminating and integrating a polyurethane surface layer in which β-chitin is dispersed on the surface of a base material or a base material layer.