JPH04194086A - Synthetic leather - Google Patents

Abstract

PURPOSE:To obtain a synthetic leather having excellent designability without lowering air-passability and moisture-permeability by laminating and integrating a wet-formed microporous polyurethane layer on the surface of a substrate and a dry-formed microporous polyurethane layer on the surface of the wet- formed layer. CONSTITUTION:A solution of polyurethane resin dissolved in a water-miscible organic solvent is applied to the surface of a substrate composed of natural, regenerated or synthetic fiber and the coating layer is coagulated in wet state to form a microporous layer. The surface of the microporous layer is coated with a W/O-type emulsion composed of a hydrophobic polyurethane, a hydrophilic polyurethane, an organic solvent and water, and the coating layer is dried by heating at about 100-150 deg.C to obtain a dry-formed microporous layer. The product is preferably crumpled under hot-wet condition to obtain a synthetic leather having luxury feeling and close resemblance to natural leather. The leather is suitable as a base material for shoes.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to synthetic leather.

[Conventional technology and Problems that the invention attempts to solve]

Synthetic leather is known in which a wet microporous layer of polyurethane resin is formed on the surface of an elastic base material in which a polyurethane resin is integrated with a base material such as a woven fabric, nonwoven fabric, or knitted fabric.

The wet microporous layer in this type of synthetic leather is created by applying a solution of polyurethane resin in a water-miscible organic solvent to the surface of the base material, immersing it in water, dissolving the water-miscible organic solvent in water, and removing the polyurethane resin. It is formed by a method of coagulating.

When it is necessary to apply a desired color to the synthetic leather produced by such a method, a coloring agent of the desired color is added to the polyurethane resin solution for forming the wet microporous layer. When the solution is wet solidified, there is a problem in that color blurring occurs and it is difficult to obtain the desired color tone.

For this reason, in the past, a polyurethane resin coating was formed by applying a polyurethane resin solution or the like on release paper and drying it, and transferring it onto the wet microporous layer. The design is improved by providing a mesodermal layer and an epidermal layer.

However, when a decorative layer made of such a polyurethane resin film is provided on a wet microporous layer, there is a problem in that air permeability and moisture permeability are reduced. Further, when this type of decorative layer is provided, there is a problem in that surface gloss occurs, making it impossible to obtain a natural leather-like appearance.

The present invention was made in view of the above points, and an object of the present invention is to provide synthetic leather with improved design without reducing air permeability and moisture permeability.

[Means to solve the problem]

That is, in the synthetic leather of the present invention, a wet microporous polyurethane layer is integrally laminated on the surface side of the base material, and a dry microporous polyurethane layer is further laminated and integrated on the surface side of the wet microporous layer. It is characterized by

〔Example〕

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

FIG. 1 shows an embodiment of the synthetic leather 1 of the present invention, in which a wet microporous layer 3 is provided on the surface side of a base material 2, and a dry microporous layer is provided on the surface of the wet microporous layer 3. 4 has been established,
Furthermore, a surface treatment layer 5 is provided on the surface of the dry microporous layer 4 as required.

The base material 2 includes natural fibers such as cotton and linen, rayon,
Woven fabrics, nonwoven fabrics, knitted fabrics, etc. made of recycled fibers such as acetate and staple fibers, and synthetic fibers such as polyamide, polyester, and polyacrylonitrile, alone or in combination with these fibers, can be used. As the base material 2, JIS L1096
Water absorption by method C is within 60 seconds, JIS L1096
Breathability by method A is 1c1! /d/sec or more is preferable, and as the base material 2, one that has been subjected to a napping treatment on both sides or one side can be used, but in order to improve the surface texture of the resulting synthetic leather, It is preferable to use a base material that has been subjected to a napping treatment on at least the surface side.

Further, as the base material 2, it is also possible to use a polyurethane-impregnated cloth obtained by impregnating and solidifying the above-mentioned woven fabric, non-woven fabric, or knitted fabric with a polyurethane resin. Polyurethane-impregnated fabric is produced by impregnating the above woven fabric, nonwoven fabric, or knitted fabric with a water-miscible organic solvent solution of polyurethane resin, and then immersing it in water to dissolve and remove the water-miscible organic solvent in water to solidify the polyurethane resin. It can be obtained by letting This polyurethane resin includes polyethylene adipate, polybutylene adipate,
Polyester glycol polyurethane, polypropylene glycol polyurethane, polytetramethylene glycol polyurethane, polycarbonate polyurethane, polytetramethylene glycol-polycarbonate containing polypropylene adipate, polyhexamethylene adipate, polycaprolactone, polymethylvalerolactone, etc. as a polyol component Polymer-based polyurethane and the like can be used. These polyurethane resins are preferably used in various ways depending on the purpose, and are 100% polyurethane resins.
The modulus is selected from a range of about 15 to 150 kg/d depending on the purpose.

As the water-miscible organic solvent used as a solvent for the polyurethane resin, an organic solvent that dissolves the polyurethane resin and is miscible with water is used, such as dimethylformamide (DMF) and dimethylacetamide (DMA).
, tetrahydrofuran (THF), dioxane (D
OX) and mixtures thereof, but usually DM
F is used.

The amount of polyurethane resin impregnated in the polyurethane resin-impregnated cloth is 15 to 6% based on the weight of the woven fabric, nonwoven fabric, knitted fabric, etc.
0% (as polyurethane resin solid content) is preferable.

The wet microporous layer 3 can be formed by applying a water-miscible organic solvent solution of a polyurethane resin to the surface side of the base material 2, and then immersing the solution in water to remove the solvent and solidifying the polyurethane resin. As the polyurethane resin for forming this wet microporous layer 3 and the water-miscible organic solvent used as a solvent for this polyurethane resin, the same ones as mentioned above are used. The amount of polyurethane resin solution applied per unit area of the base material 2 for forming the wet microporous layer 3 is 10 in terms of the solid content of the polyurethane resin.
The amount is preferably 0 to 500 g/rrr.

A dry microporous layer 4 is formed on the wet microporous layer 3 thus formed. The dry microporous layer 4 is formed by applying a water-in-oil emulsion of polyurethane consisting of hydrophobic polyurethane, hydrophilic polyurethane, an organic solvent, and water onto the wet microporous layer 3 after drying using a knife coater or the like. It can be formed by drying it by passing it through a heating drying oven or the like. In addition, a water-in-oil emulsion of polyurethane is coated on the release paper and heated and dried to form a dry microporous layer on the release paper. It may also be formed by heat laminating or laminating with an adhesive, then peeling off the release paper and transferring. In either method, when a water-in-oil emulsion of polyurethane is applied and dried by heating, the organic solvent in the emulsion is first heated for about 2 to 5 minutes at a temperature of about 60 to 80"C, especially to scatter the organic solvent in the emulsion. After that, it is preferable to dry the emulsion by heating it for about 1 to 5 minutes at a temperature of about 100 to 150° C. to scatter the water in the emulsion.

Hydrophobic polyurethanes constituting the water-in-oil emulsion of polyurethane include, for example, polyethylene adipate, polybutylene adipate, polypropylene adipate, polyhexamethylene adipate, polycaprolactone, polymethylvalerolactone, and polycarbonate having a molecular weight of about 300 to 4000. Hydrophobic polyols such as polyols, organic diisocyanates such as diphenylmethane diisocyanate, tolylene diisocyanate, phenylene diisocyanate, isophorone diisocyanate, dicyclohexyl diisocyanate, hexamethylene diisocyanate, and ethylene glycol, propylene glycol, diethylene glycol, butanediol, hexanediol, ethylenediamine. , propanediamine, trimethylenediamine, tetramethylenediamine, hexamethylenediamine, isophoronediamine, dicyclohexyldiamine, m-xylenediamine, and other chain extenders.

Two or more of the above hydrophobic polyols, organic diisocyanates, and chain extenders can be used in combination.

On the other hand, hydrophilic polyurethanes include, for example, polyurethane polymers having polyoxyethylene chains, and these polymers are usually prepared by reacting diisocyanate compounds with hydrophobic polyols, polyoxyethylene glycol, derivatives thereof, and chain extenders. obtained by. Other examples include copolymerization of a hydrophobic unsaturated double bond-containing urethane compound and a hydrophilic vinyl monomer. Urethane compounds containing unsaturated double bonds are
A method of reacting a hydrophobic polyol or an organic diisocyanate in the presence of a chain extender having an unsaturated double bond, or a method of reacting a urethane prepolymer with an isocyanate group (or hydroxyl group) and a hydroxyl group (or isocyanate group) with an unsaturated double bond-containing compound. Hydrophilic vinyl monomers to be copolymerized with this unsaturated double bond-containing urethane compound include vinyl monomers having carboxyl groups, sulfonic acid groups, sodium sulfonate bases, tertiary amino groups, quaternary ammonium bases, etc. can be mentioned. Examples of such substances include acrylic acid, methacrylic acid, maleic acid, itaconic acid, vinyl sulfonic acid, sulfonated styrene, sodium styrene sulfonate, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, vinylpyridine, hydroxy methacrylate, etc. Examples include propyltrimethylammonium chloride.

The ratio of the hydrophobic polyurethane and hydrophilic polyurethane in the water-in-oil emulsion is very high! Ratio of hydrophobic polyurethane: hydrophilic polyurethane = 90:10~
50:50 is preferred.

Examples of organic solvents include methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), diethyl ketone,
Methyl formate, ethyl formate, propyl formate, methyl acetate,
Ethyl acetate, butyl acetate, acetone, cyclohexane,
Tetrohydrofuran, dioxane, methanol, ethanol, isopropanol, butanol, toluene, xylene, dimethylformamide (DMF), dimethyl sulfoxide, methyl cellosolve, butyl cellosolve, cellosolve acetate, trichlorethylene, etc. are used. These organic solvents can also be used as a mixture as appropriate.

The proportion of the organic solvent in the water-in-oil emulsion of polyurethane is preferably 200 to 600 parts by weight per 100 parts by weight of the total solid content of the polyurethane. The proportion of polyurethane in the water-in-oil emulsion is 15
~35% by weight is preferred.

A coloring agent, a light stabilizer, an ultraviolet absorber, an antioxidant, etc. can be added to the water-in-oil emulsion of the polyurethane, if necessary.

The coating amount of the water-in-oil emulsion per unit area for forming the dry microporous layer 4 is preferably 30 to 200 g/rrf in terms of polyurethane solid content. The dry microporous layer 4 can be formed by applying a water-in-oil emulsion of polyurethane and then drying it by heating.

The size of the pores in the dry microporous layer 11 is smaller than the pore size in the wet microporous layer 10, and is about 1 to 5 μm.

The synthetic leather obtained in this way has a soft texture and a sense of unity, but when it is further kneaded under thermal conditions, it becomes even softer and has drape properties, and it is similar to natural leather. Natural wrinkles appear when rubbed. This is a wet microporous layer 10 to a dry microporous layer 11.
This is thought to be due to the gradual increase in density toward the surface. Furthermore, the wrinkles caused by rubbing are maintained for a long period of time, and it is possible to obtain synthetic leather that is similar in appearance and texture to natural leather.

The surface treatment layer 5 provided on the surface side of the dry microporous layer 4, if necessary, can be formed by applying a surface treatment agent to the surface of the dry microporous layer 4. In order not to reduce moisture, it is preferable to apply by gravure coating method, screen method, etc. As the surface treatment agent for forming the surface treatment layer 5, in addition to conventional non-yellowing polyurethane and these modified polyurethanes, non-yellowing silicone-modified polyurethane, non-yellowing fluorine-modified polyurethane, and non-yellowing polyurethane can be used. Amino acid-modified polyurethane and the like can be used. In addition, the surface treatment layer 5 has a solid content of 2 to 20 g of surface treatment agent per unit area.
It is preferable to form it so that it is about rrf.

The present invention will be explained in more detail by giving specific examples below.

Example 1 A nonwoven fabric with a thickness of 0.4 mm in which polyester fibers were entangled was mixed with a 10% DMFi solution of a polyurethane elastomer with a 100% modulus of 60 kg/c- containing polyethylene adipate as a polyol component (coloring agent per 100 parts by weight of elastomer). 3 parts by weight), then squeezed with a squeeze roll, immersed in water at 20°C to remove the solvent, coagulate the polyurethane, and after dehydration,
By drying under hot air at 0°C, a base material having a polyurethane fiber adhesion amount of 50 g/rrf in terms of polyurethane solid content and a thickness of 0.4 mm was obtained.

Next, on one side of the base material, the 100% modulus of polyethylene adipate as a polyol component was 50 kg/ci.
A 15% DMF solution of the polyurethane elastomer (containing 3 parts by weight of colorant, 2 parts by weight of surfactant, and 5 parts by weight of filler per 100 parts by weight of elastomer) of the polyurethane elastomer (i) was coated with a knife coater in an amount of 200 g/m in terms of urethane solid content. rf
After coating, the polyurethane solution was immersed in water at 20°C and then in warm water at 60°C to fully extract and remove DM'F in the applied polyurethane solution. After dehydration, it was dried under hot air at 120°C to obtain a sheet having a thickness of 0.6 mm and having a microporous layer on the surface.

Next, polyethylene adipate and polyoxyethylene glycol (weight ratio 70:3) were applied to the surface of the wet microporous layer.
The 100% modulus with 0) as the polyol component is 25
A water-in-oil emulsion containing 30% by weight of polyurethane (solvent: MEK:water = 9 by weight)
Furthermore, 1 part of a mixed organic solvent of MEK and toluene (90:10 mixture by weight) was added per 100 parts by weight of polyurethane solid content of this water-in-oil emulsion.
50 parts by weight, 150 parts by weight of water, 10 parts by weight of colorant, and 0.5 parts by weight of light stabilizer, and this was coated with a knife coater.
After coating so that the coating amount per unit area is 50 g/rrf in terms of polyurethane solid content,
The mixture was heated for 3 minutes and then dried at I 20 'C for 3 minutes to form a dry microporous layer.

When the resulting synthetic leather was rubbed under thermal conditions,
The texture became softer, drapeability was imparted, and wrinkles were formed that were retained over a long period of time, and the wrinkles were very similar to those of natural leather. Moreover, the surface of this synthetic leather had good lubricity and a desired matte color tone, and had a luxurious appearance and feel that was far superior to natural leather.

The moisture permeability of this synthetic leather was 4000 g/rd/24 hours (according to JIS ZO20B method), and it was suitable as a shoe lining sheet.

Example 2 A double-sided raised fabric with a thickness of 0.85 m woven in a twill weave using a 20-count double-sided fabric made of a blend of polyester fiber and rayon fiber was laid in one direction to improve the surface smoothness. After heating the raised side of the brushed surface along a heating roll and modifying the surface of the raised surface, the modified surface is coated with polybutylene adipate having a 100% modulus of 40 kg/cd as a polyol component. 18% DMF solution of polyurethane elastomer (elastomer 100
Per part by weight, 10 parts by weight of colorant, 2 parts by weight of surfactant,
Filler 3! After coating with a knife coater so that the coating amount was 250 g/bot in terms of urethane solid content, it was immersed in water at 20"C, and then in warm water at 60 °C. DMF in polyurethane solution
was thoroughly removed by extraction into water. After dehydration, dry under hot air at 120°C to form a layer with a wet microporous layer on the surface and a thickness of 1.
A 0- sheet was obtained.

Next, a dry microporous layer was formed on this wet microporous layer using a water-in-oil polyurethane emulsion having the same composition as in Example 1 under the same conditions. Furthermore, on this dry microporous layer,
A toluene/isopropyl alcohol solution of polyester polyurethane having a 100% modulus of 50 kg/d was printed using a gravure printer to form a surface treatment layer in which the surface treatment agent per unit area was 5 g/day in terms of solid content. When the resulting synthetic leather was rubbed under thermal conditions, it became softer in texture, imparted drapability, and created wrinkles that were retained over a long period of time. was very close to that of Moreover, the surface of this synthetic leather had good lubricity and a desired matte color tone, and had a luxurious appearance and feel that closely resembled natural leather.

The moisture permeability of this synthetic leather was 3500 g/rrf/24 hours, making it suitable as a shoe lining material.

Comparative Example 1 A nonwoven fabric similar to that of Example 1 was impregnated with a DMF solution of the same polyurethane elastomer, and then immersed in water to coagulate the polyurethane to obtain a polyurethane-impregnated fabric. A wet microporous layer of polyurethane was formed in the same manner as in Example 1.

On the other hand, the 100% modulus of polyethylene adipate as the polyol component on the release paper with aperture is 90 kg/di.
of polyurethane elastomer in 23% DMF/) toluene solution (5% by weight of colorant per 100 parts by weight of polyurethane)
(containing) was applied using a knife coater to a dry thickness of 10 nm, and then heated and dried at 90°C for 1.5 minutes to form a layer that would become the skin layer.Next, polyethylene adipate was applied on this layer. After applying a 21% DMF/MEK solution (containing 20 parts by weight of colorant per 100 parts by weight of polyurethane) of a polyurethane elastomer with a 100% modulus of 40 kg/Cm as a polyol component using a knife coater so that the dry thickness becomes 3 On. , 2 at 90°C
After heating and drying for a minute to form a layer that will become the mesothelial layer, the layer side that will become the mesothelial layer is laminated and integrated by pressing the wet microporous layer surface to the wet microporous layer surface while heating the wet microporous layer surface to 140 ° C.
After that, the release paper is peeled off and a medium layer is placed on the wet microporous layer.
Synthetic leather having a skin layer was obtained.

Although the resulting synthetic leather had excellent durability, it lacked surface lubricity even when rubbed under heat. In addition, the moisture permeability was 500 g/rrf724 hours or less, which was poor in moisture permeability, and the surface had a strong gloss and lacked surface smoothness, so it was hard to say that it had a natural leather-like appearance.

〔Effect of the invention〕

As explained above, the synthetic leather of the present invention not only has a matte surface with excellent surface smoothness, but also has natural wrinkles similar to natural leather when rubbed, etc., and these wrinkles are retained for a long period of time. It has a high-quality appearance similar to natural leather.

In addition, it has high moisture permeability and can obtain the desired color tone while maintaining excellent moisture permeability, and has an appearance and feel that is more similar to natural leather than conventional synthetic leather. .

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a longitudinal sectional view showing one embodiment of the synthetic leather of the present invention. 1...Synthetic leather 2...Base material 3...Wet microporous layer 4...Dry microporous layer Surplus 5 sentences wandering snake 7 Lli

Claims (1)

[Claims] A synthetic leather characterized in that a wet microporous layer of polyurethane is integrally laminated on the surface side of a base material, and further a dry microporous layer of polyurethane is integrally laminated on the surface side of the wet microporous layer.