JPH09250090A - Manufacturing method of synthetic leather - Google Patents

Abstract

(57) Abstract: A fibrous base material and a thermoplastic elastomer, which are problems of the melt film-forming lamination method in a method for producing a synthetic leather composed of a fibrous base material and a melt-formed thermoplastic elastomer layer. The problem of low adhesive strength with the layer is solved. SOLUTION: A thermoplastic elastomer having a flow starting temperature lower than the flow starting temperature of the thermoplastic elastomer forming the thermoplastic elastomer layer by 20 ° C. or more is applied to the surface of the fibrous base material with a solution, and then the heat treatment is performed. Melt film formation of the plastic elastomer layer.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention has a silver surface layer which has extremely high surface strength and peeling strength, is flexible, has excellent working environment because it does not use an organic solvent in the surface finishing process, and can be manufactured at low cost. The present invention relates to a method for manufacturing synthetic leather.

[0002]

2. Description of the Related Art Conventionally, as a method for producing a synthetic leather with a silver surface layer, a polyurethane solution is applied to a release paper, dried to form a film, and the film is a base material made of a woven or non-woven fabric. A so-called dry method, which is a method of adhering the release paper to the surface of the sheet with an adhesive and peeling the release paper, is generally used. Further, on the surface of the substrate, a polyurethane solution is applied, a porous polyurethane layer is formed by a wet coagulation or dry coagulation method, and a resin solution containing a colorant is applied thereon and dried to form a colored layer. A method of forming a concavo-convex pattern with an embossing roll is also generally used.

[0003] Also, JP-A-53-62803 discloses that
On the synthetic resin layer formed on the base material, a synthetic resin melt is extruded in a film shape by using an extruder, and a method for producing a synthetic leather for embossing the surface with integration is described,
In addition, in Japanese Patent Publication No. 7-3033, T-
A method of making a sheet for laminating a polyurethane melt extruded from a die is described.

[0004]

However, in these known methods, a large amount of an organic solvent that deteriorates the working environment is used, or irregularities due to the base material that give a cheesy impression to the surface when pulled appear. In addition, the base layer and the surface layer are easily separated from each other, and it takes a long time to solidify the surface layer, so that the speed of the manufacturing process cannot be increased, resulting in higher manufacturing cost. It has a problem that it cannot be obtained. The present invention provides a method for producing synthetic leather that does not have the above-mentioned problems, that is, it does not deteriorate the working environment by not using a large amount of organic solvent, and the production process , The production cost is low, and the resulting synthetic leather has no silverish surface when tensioned and has a high-grade silver surface layer that cannot be obtained by conventional methods. It is an object of the present invention to provide a method for producing synthetic leather that is unlikely to peel.

[0005]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors have found that an elastomer for forming a resin layer to be applied to the surface of a fibrous base material in advance before melt extrusion processing. 20 below the flow start temperature of
The peel strength is improved by applying and drying a solution of a thermoplastic elastomer having a flow starting temperature lower than ℃.
The inventors have found the fact of being stable and have reached the present invention.

That is, the present invention has a thermoplastic elastomer layer produced by the melt film-forming method on the surface of a fibrous base material, and the surface of the thermoplastic elastomer layer has an uneven pattern or a mirror pattern. In producing the synthetic leather, a thermoplastic elastomer having a flow starting temperature lower than the flow starting temperature of the thermoplastic elastomer forming the thermoplastic elastomer layer by 20 ° C. or more is applied to the surface of the fibrous base material in a solution. A method for producing synthetic leather is characterized in that the thermoplastic elastomer layer is melt-cast after being dried.

The present invention will be described in detail below. First, the fibrous base material used in the present invention can be used as long as it is a sheet having an appropriate thickness and a sense of fulfillment and having a soft texture, and thus can be used in a conventional method for producing a leather-like sheet. Various types of fibrous base materials that have been used can be used as they are in the present invention. For example, ultrafine fibers or bundled fibers thereof, entangled non-woven sheets made of normal fibers, natural fibers, etc., knitted woven sheets, and / or fibers containing a polymer elastic body such as polyurethane as a binder between the fibers of the sheets. Quality substrates. The fineness of the fibers forming the ultrafine fiber bundle is preferably 0.5 denier or less,
It is particularly preferably 0.1 denier or less, and the total denier of the ultrafine fiber bundle is preferably in the range of 0.5 to 10 denier. Examples of the type of fiber include nylon-based fiber and polyester-based fiber.

Among them, as a fibrous base material having a texture closest to that of natural leather, a fiber sheet having a polymeric elastic body in a non-woven fabric composed of ultrafine fiber bundles can be mentioned as a preferred example. The elastic polymer to be impregnated into the nonwoven fabric is a resin that has been conventionally used for manufacturing a leather-like sheet, and includes polyurethane resin, polyvinyl chloride resin, polyvinyl butyral resin, polyacrylic acid resin, and polyacrylic acid resin. Examples thereof include amino acid-based resins, silicone-based resins and mixtures of these resins, and these resins may of course be copolymers. As the polymer elastic body constituting at least the surface portion of the fibrous base material, the same kind as the thermoplastic elastomer used for the surface finish is preferable in terms of adhesiveness, and particularly polyurethane is capable of obtaining strength and natural leather-like performance. It is preferable in terms. The weight ratio of the fibers constituting the fibrous base material to the elastic polymer is preferably in the range of 90:10 to 40:60 by weight. The thickness of the fibrous base material can be arbitrarily selected depending on the use of the obtained synthetic leather and is not particularly limited, but from the viewpoint of the balance with the intermediate layer and the surface layer, it is preferably 0.3 mm to 3 mm, particularly Preferably 0.5 mm-2.
The range is 0 mm.

As the thermoplastic elastomer to be applied on the surface of the fibrous base material in advance, conventionally known resins can be used, but those having adhesiveness to the fibrous base material and the same kind as the resin used for the surface layer described later are used. Some of them are preferable in terms of compatibility and adhesive strength. When the thermoplastic elastomer forming the surface layer is polyurethane, for example, an average molecular weight of polyester diol, polyether diol, polyester polyether diol, polylactone diol, polycarbonate diol or the like is 500 to 3500.
Polyurethanes obtained by reacting at least one selected from the above polymer diols with an organic diisocyanate and a chain extender having two active hydrogen atoms. These polyurethanes may be a mixture of two or more different kinds of polyurethanes. Further, other thermoplastic resins may be blended depending on the purpose. As a coating method, known methods such as a gravure method and a spray method are used. The coating amount may be appropriately adjusted depending on the material, physical properties and surface condition of the fibrous base material, and is usually applied within a range of 1 to 10 g / m ^{2 in} terms of solid content.

It is a very important requirement in the present invention that the flow starting temperature of the thermoplastic elastomer is lower than the flow starting temperature of the resin forming the surface layer by 20 ° C. or more.
With this, when the melt-extruded thermoplastic elastomer layer in a film state and the fibrous substrate are laminated, the resin on the surface of the fibrous substrate previously applied is softened by the heat of the thermoplastic elastomer layer and the thermoplastic elastomer layer By adhering and simultaneously penetrating the fibrous substrate,
Peeling is less likely to occur between the thermoplastic elastomer layer and the fibrous substrate. When the temperature is lower than 20 ° C, softening hardly occurs, the adhesiveness is not improved, and unevenness occurs. When a polyurethane elastomer is used as the thermoplastic elastomer, the flow initiation temperature can be easily changed by changing the average molecular weight of the polymer diol as the raw material and the molar ratio of the polymer diol and the chain extender.

When the flow starting temperature is lower than 100 ° C.,
Even if it becomes a product, it is not preferable because it is likely to be deformed due to a slight environmental change or a heating change in the manufacturing process or the processing process. Therefore, the flow starting temperature of the thermoplastic elastomer is between 100 ° C. and 20 ° C. lower than the flow starting temperature of the surface layer forming resin. More preferably, the temperature is 23 ° C. or lower than the flow starting temperature of the surface layer forming resin.

Next, a method of molding the surface layer will be described. In the surface layer, there are many items related to quality such as color tone, uneven pattern, surface physical properties, and tactile sensation, and the optimum conditions may be appropriately selected depending on the application, but strength, durability and natural leather-like performance are obtained. , Thermoplastic polyurethane is preferred. As the polyurethane, conventionally known polyester-based, polyether-based, polycarbonate-based and the like can be used, but various kinds of mixtures may be used, and other thermoplastic elastomers may be blended. The flow starting temperature of the resin used for the surface layer is preferably 130 ° C to 220 ° C, particularly preferably 150 ° C to 200 ° C.

The surface layer may be molded by adding a colorant, an antioxidant, a foaming agent, etc. to the thermoplastic elastomer chips, if necessary, and melt-kneading the mixture under heating and pressurizing with an extruder. , A film is extruded from a T-die in a molten state into a film, and in a fluid state, it is pressed and solidified on a fibrous substrate to form a surface layer. The thickness of the surface layer varies depending on the type and performance of the thermoplastic elastomer, but in general it has a leather-like texture and is 10 μm or more and 400 μm or more in order to satisfy the physical properties such as surface strength, adhesive strength and flexibility. The following is preferable and 30
More preferably, it is not less than μm and not more than 300 μm. When the thickness of the surface layer is too thin, the pigment concentration (with respect to polyurethane) in the case of coloring in the same color tone becomes high, and the surface physical properties are deteriorated. On the other hand, if the thickness of the surface layer is too large, the flexibility is deteriorated and a rubber-like feeling is not preferred. Of course, the surface layer may be composed of one layer, or may be composed of two or more layers. In the case of being composed of multiple layers, the flow starting temperature of the resin used for the surface layer in the present invention means the flow starting temperature of the resin forming the layer in contact with the fibrous substrate. Preferably, the layer in contact with the fibrous substrate is a melt-formed foam layer, and a melt-formed non-foam layer is formed on the foam layer.

As a method of forming an uneven pattern or a mirror pattern on the surface, a thermoplastic elastomer melt-extruded in a film shape from a T-die is sandwiched between a release paper having an uneven pattern or a mirror pattern and a fibrous substrate. Method of pressing with a roll and pressing, a method of pressing the thermoplastic elastomer between the fibrous substrate and the shaping roll to adhere to the fibrous substrate and shaping on the surface, a surface layer on the fibrous substrate with a pressing roll There is a method of forming a concavo-convex pattern with a heated embossing roll while the thermoplastic elastomer for the surface layer has fluidity after being adhered, but the method is not particularly limited. To increase productivity, that is, increase production speed,
A method of simultaneously performing adhesion and shaping with a shaping roll is preferable.
The imprinting roll referred to in the present invention is an embossing roll having a mirror surface or an embossed pattern with a concavo-convex pattern on the surface, and may be a combination of a releasable embossed sheet and a normal roll. Preferably, the surface is an embossing roll having a mirror surface or an embossing pattern with a concavo-convex pattern, and when an embossing roll with a mirror surface pattern is used, an enamel-like synthetic leather will be obtained, but in some cases, an enamel tone obtained The surface of the may be embossed with unevenness to form an uneven pattern on the surface.

As a method of pressing the thermoplastic elastomer extruded in the form of a film between the fibrous base material and the shaping roll, the thermoplastic elastomer is extruded onto the fibrous base material in advance and then the shaping roll is used. A method of pressing through a back roll facing the shaping roll, a thermoplastic elastomer is extruded onto the shaping roll, and then a fibrous base material is fed between the backing roll and the shaping roll. There is a method of pressing by pressing, or a method of directly extruding the thermoplastic elastomer between the fibrous base material and the shaping roll and pressing it by the back roll which is opposed, but the thermoplastic elastomer has fluidity at the time of pressing. Whichever method you use, there is no big difference.

As the material of the roll, a metal roll is used in the case of the emboss roll. The back roll may be either a metal roll or an elastic roll, but it is preferable to use the elastic roll from the viewpoint of the stability of pressing. The pressing pressure may be set according to the fluidity of the thermoplastic elastomer under conditions that satisfy moldability and adhesive strength. The laminate whose surface is shaped is peeled from the shaping roll after the temperature of the thermoplastic elastomer is substantially lowered and the fluidity is lost. If the thermoplastic elastomer is peeled while still having fluidity, the uneven pattern or the mirror surface pattern is broken, so-called grain flow occurs, and a sheave uneven pattern or an extremely smooth mirror surface cannot be obtained. For this reason, it is preferable that the embossing roll has a structure in which a cooling liquid is circulated inside the roll as necessary, or a structure in which the vicinity of a peeling point is forcibly cooled by cold air.

The synthetic leather of the present invention is produced as described above, but if necessary, in order to improve the abrasion resistance, antifouling property and the like of the surface, or to impart a deeper color tone, the resin A surface finishing agent, a coloring agent or the like may be added.

The flow starting temperature is measured by the following method.・ Apparatus name: Koka type flow tester (manufactured by Shimadzu Corporation) ・ Measurement conditions Nozzle: Diameter 1 mm x length 10 mm Load: 100 kgf Measurement start temperature: Medium to high hardness (JISA: 80 to 97A) 150 ° C Low hardness (JISA) : 65 to 75 A) 100 to 130 ° C. Preheating time: 6 to 10 minutes Temperature rising rate: 5 ° C./minute Outflow start temperature: Outflow rate Q (ml / sec) is in the range of 1 × 10 −3 to 4 × 10 −3 Data is plotted and calculated by extrapolation.

[0019]

EXAMPLES The present invention will now be specifically described with reference to Examples.
The present invention is not limited to these examples. The parts and% in the examples relate to weight unless otherwise specified.

Example 1 50 parts by weight of polyethylene as a sea component and 50 parts by weight of 6-nylon as an island component were melt-spun in the same melting system to produce a composite fiber having a single fiber fineness of 10 denier. The composite fiber was drawn 3.0 times, crimped, cut into a fiber length of 51 mm, defibrated with a card, and then made into a web by a cross wrapper webber. Next, a fiber entangled nonwoven fabric having a basis weight of 650 g / m ^{2 was obtained} by needle punching. This non-woven fabric was impregnated with a solution consisting of 18 parts by weight of a polyurethane composition mainly composed of polyester polyurethane and 82 parts by weight of dimethylformamide, coagulated and washed with water,
The polyethylene contained in the composite fiber is extracted and removed to have a thickness of 6-nylon ultrafine fiber bundle fibers and polyurethane.
A 3 mm fibrous substrate was obtained.

On one side of this fibrous substrate, an average molecular weight of 20
00 polycarbonate diol, average molecular weight 2000
Polytetramethylene glycol, average molecular weight 2000
Polyethylene glycol, 4,4′-dicyclohexylmethane diisocyanate and ethylene glycol (the molar ratio is 0.4: 0.4: 0.2:
A polyurethane composition solution containing polyurethane as a main component obtained by polymerization from 2: 1) was applied by a gravure roll so that the solid amount applied was 5.5 g / m ^2, and dried. This polyurethane solution was evaporated to dryness to form a film, and the flow starting temperature was measured and found to be 165 ° C.

As the surface layer resin, a polyester diol having an average molecular weight of 2000 obtained from 1,9-nonanediol, isophthalic acid and adipic acid, butanediol, and 4,4'-diphenylmethane diisocyanate (mol Ratio is 1: 3.6: 2.6)
Was continuously supplied from a metering pump to a twin-screw type extruder rotating in the coaxial direction to carry out continuous melt polymerization at a temperature of 260 ° C. The resulting thermoplastic polyurethane melt was continuously extruded in strands into water and then cut with a pelletizer to produce pellets. The pellets were dehumidified and dried at 80 ° C. for 6 hours. The flow starting temperature of this polyurethane was 190 ° C.

Using a extruder and a T-die, a polyurethane composition prepared by mixing 100 parts of the above pellets and 5 parts of white pigment pellets (pigment concentration 30%: resin polyethylene) was used.
Between the release paper (DE-14: manufactured by Dai Nippon Printing Co., Ltd.) and the fibrous base material, which have a melting zone temperature of 235 ° C., a die introduction temperature of 235 ° C., and are in a molten state while forming a film into a film, and have a textured uneven pattern. And a metal roll and an elastic roll were pressed to obtain a non-porous surface layer having a texture and an average thickness of 200 μm. The peel strength of the surface layer was 9.5 kg / 25 mm. Further, a leather-like sheet having a strong surface strength and having a good sensitivity without causing a chewy unevenness when pulled was obtained. The physical properties of the obtained leather-like sheet are shown in Table 1 below.

Comparative Example 1 A leather-like sheet was obtained in the same manner as in Example 1 except that the polyurethane solution having a flow starting temperature of 165 ° C. was not applied to one surface of the fibrous substrate. . The physical properties of this leather-like sheet are shown in Table 1 below. Comparative Example 2 As a thermoplastic elastomer previously applied to a fibrous base material, a polycarbonate diol having an average molecular weight of 2000, tetramethylene glycol, 4,4′-diphenylmethane diisocyanate, ethylene glycol (molar ratio 0.5: 0.5: 4: A leather-like sheet was produced in the same manner as in Example 1 except that the polyurethane composition solution mainly composed of the polyurethane obtained by polymerization from 3) was used. The surface strength of the obtained product was at the same level as in Example 1, but the peel strength was low at 6.5 kg / 25 mm, and the feeling of unity between the surface layer and the fibrous base material was lacking. On the peeled surface, a portion peeled at the interface between the surface layer and the fibrous base material was observed. A solution of this polyurethane was evaporated to dryness to form a film, and the flow starting temperature was measured and found to be 187 ° C.

[0025]

[Table 1]

[0026]

As described above, the present invention is a method for producing a synthetic leather comprising a fibrous base material and a melt-formed thermoplastic elastomer layer, wherein the fibrous base material is coated with a specific thermoplastic elastomer. As a result, when the thermoplastic elastomer layer is laminated, the resin applied by the heat of fusion of the layer is softened, and as a result, the fibrous base material and the thermoplastic elastomer layer, which are problems of the melt film-forming laminating method. The problem of low adhesive strength with is solved. The synthetic leather of the present invention thus obtained is used as a material for shoes and boots, as a material for bags and bags, and as a material for clothing such as camera cases, belts, wallets, coats, blazers and skirts. You can

Claims (1)

[Claims] 1. A synthetic method in which a surface of a fibrous base material has a thermoplastic elastomer layer produced by a melt film-forming method, and the surface of the thermoplastic elastomer layer has an uneven pattern or a mirror-like pattern. In producing leather, after applying a solution of a thermoplastic elastomer having a flow starting temperature of 20 ° C. or more lower than the flow starting temperature of the thermoplastic elastomer forming the thermoplastic elastomer layer on the surface of the fibrous base material and drying the solution. A method for producing synthetic leather, characterized in that the thermoplastic elastomer layer is melt-cast.