JPH082321B2 - Method for manufacturing synthetic leather shoes - Google Patents

Description

The present invention relates to a method for producing synthetic leather dyed with an acid dye.

[Prior Art] Conventionally, as a method for dyeing synthetic leather, a method of dyeing a surface layer of synthetic leather made of nylon elastomer or polyurethane elastomer with an acid dye having an acidic group such as a sulfone group or a carboxyl group in a molecule is used. Proposed.

[Problems to be solved by the invention]

By the way, the skin layer of the synthetic leather made of the polyurethane elastomer or the like originally has relatively good adhesiveness to the synthetic resin such as polyvinyl chloride resin, while the synthetic leather and the synthetic resin dyed with an acid dye are used. Then, it was found that the adhesiveness was significantly deteriorated.

For this reason, for example, when synthetic leather dyed with this acid dye is used as a shoe skin, in the injection molding process of the shoe sole, the adhesiveness between the bottom of the skin and the polyvinyl chloride resin sole material is Poorly, there was a risk of peeling off the bond between the skin and the sole.

Therefore, conventionally, in order to prevent peeling at the adhesion portion between the skin and the sole, for example, the thermal softening point is 90 ~ 170 ℃.
In addition, a non-yellowing polyurethane resin solution that employs polybutylene adipate, polybutylene hexylene adipate, poly-ε-caprolactone, etc. as the polyester component is used as an adhesive on the lower part of the skin that is adhered to the shoe sole by hand beforehand. A coating process had to be provided. However, the work of applying the adhesive may be time-consuming and the productivity may be deteriorated, or the adhesive may be adhered even to the non-adhesive part of the scab and the appearance of the shoe may be deteriorated.

Further, the synthetic leather dyed with the conventional acid dye has a high concentration of molecules of the acid dye on the surface portion of the surface layer,
The fastness to wet rubbing, which indicates the degree of discoloration when washed with a detergent, is relatively low, and, for example, in the overlapping portion of synthetic leather and the sole material, this acid dye is transferred to the sole material side via an adhesive. It was easy to cause migration (dye transfer).

The present invention has been made on the basis of such a conventional technique, and the skin has improved adhesion to general synthetic resins, particularly polyvinyl chloride, improved wet friction fastness, and migration (dye transfer). It is intended to provide a method for producing a synthetic leather shoe capable of preventing the above.

[Means for solving problems]

That is, according to the present invention, a synthetic leather obtained by dyeing the surface layer of synthetic leather with an acid dye and then reducing and washing the surface portion of the surface layer with a reducing agent is cut and sewn to form a scabbard of a shoe. Then, hang this skin on the last mold, and then place the last mold on which this skin is hung on the side mold and the bottom mold by fitting it into the side mold and bottom mold. It is intended to provide a method for producing a synthetic leather shoe, which comprises injecting a shoe sole molding material containing vinyl as a main ingredient and injection-molding the shoe sole.

First, the synthetic leather used in the present invention is an industrially produced imitation leather including an artificial leather having breathability and moisture permeability, for example, a base material layer made of cloth, a microporous layer laminated thereon, And a synthetic resin skin layer laminated on the microporous layer.

Examples of the base material layer made of the cloth include a sheet-like base material mainly composed of fibers such as woven cloth, non-woven cloth, and knitted cloth, and if desired, the polymer may be impregnated and solidified as a binder. .

Examples of the fibers include natural fibers such as cotton, hemp, and wool, and synthetic fibers (artificial fibers) such as rayon, acetate, nylon, polyester, polyacrylonitrile, vinylon, and polyolefin. In the case of synthetic fibers, Not only single-spun fibers, but also mixed or spun fibers of these or these with other polymers can be used.

When a mixed or composite spun fiber is used, at least one of the polymers constituting the fiber is extracted and removed at any stage, or a method of dividing the polymer is adopted. Is preferred.

As the binder optionally used in the base material layer, as the binder generally used for leather, any binder generally used for leather can be used, for example, polyurethane elastomer, polyvinyl chloride, natural Rubber or synthetic rubber is used. These binders are adhered to a sheet mainly composed of fibers by an impregnation method, a coating method, etc. in a solution, emulsion, etc. according to need, and coagulated by a dry method or a wet method, but a sponge by a wet coagulation method. It is preferable to use a porous structure having the above because the quality such as texture and tear strength is excellent.

Synthetic leather used in the present invention, on the base layer,
It has a microporous layer made of a polymer mainly composed of polyurethane elastomer.

The polyurethane elastomer used in this microporous layer preferably has a nitrogen content based on diisocyanate of 3 to 7% by weight.

In this polyurethane elastomer, in addition to a filler, a stabilizer, a pigment, a dye, a foaming agent, a coagulation regulator, etc., if necessary, a polymer having a good compatibility in a solution state, such as polyvinyl chloride or polyvinyl acetate. , Polyvinyl formal,
A methacrylic acid resin, a vinyl chloride-vinyl acetate copolymer or the like may be mixed.

The microporous layer preferably has a porous structure in terms of folding texture, texture, and the like. The method for forming the microporous layer is as follows: a base material layer is coated with a solution of a polymer mainly composed of the polyurethane elastomer, and then a liquid having an affinity for a solvent but no affinity for the polymer is used. A method in which the polymer is solidified by immersing in

It is also possible to use a method in which this microporous layer is prepared in advance on a support and then bonded to the base material layer.

Further, on the surface of the leather-like sheet having the base material layer and the microporous layer, a finishing layer containing additives such as a matting agent and a coloring agent (dye and / or pigment) in the polymer, if necessary. Is laminated on the skin layer. The amount of the additive used in the skin layer is usually 1 to the polymer.
A range of 300% by weight is preferred. As the polymer used for the skin layer, a polyurethane elastomer having excellent economical efficiency, flexibility and abrasion resistance is used.

Among these, a polyurethane elastomer in which a diamine such as ethylenediamine, hexamethylenediamine, cyclohexylmethanediamine, isophoronediamine, N-ethyldiethanolamine, propylenediamine, butylenediamine, or an amine compound is used as a part or all of the chain extender is preferable.

Further, this polyurethane elastomer is preferably a polyester component, such as polybutylene adipate, polybutylene hexylene adipate, or poly-ε-caprolactone, alone or in combination, in order to improve the adhesiveness to the polyvinyl chloride resin. In order to improve the internal diffusion of dye molecules, polyethylene glycol or the like may be used in combination as a small amount of hydrophilic component.

Further, considering the light resistance of this polyurethane elastomer after dyeing, the isocyanate component is isophorone diisocyanate, hexamethylene diisocyanate,
Non-yellowing type aliphatic or alicyclic diisocyanates such as 4,4'-dicyclohexylmethane diisocyanate are preferred.

As a method of further improving the dyeability, there is a method of quaternizing the nitrogen of a chain extender amine compound, and examples of the quaternizing agent of an amine compound include propiolactone, propane sultone, dimethylsulfate, and further methyl chloride. Alkyl halides such as methyl bromide, ethyl bromide and butyl bromide, aralkyl halides such as benzyl chloride and benzyl bromide, epihalohydrin, quinochloroacetate and the like can be used.

The thermal softening point of this polyurethane elastomer is
90 ~ 170 ℃ is preferable, usually the dyeing bath temperature during dyeing is 60 ~ 9
Considering that the process is performed at 5 ° C, the range of 130 ° C to 170 ° C is more preferable.

In addition, as a preferable example of this polyurethane elastomer, for example, a polyurethane produced by reacting an organic diisocyanate, a polymer polyol, and a low-molecular polyfunctional active hydrogen atom-containing compound described in JP-B-55-41688. An elastomer, wherein a quaternary nitrogen atom-containing polyol is used as at least a part of the high molecular weight polyol and / or the low molecular weight polyfunctional active hydrogen atom-containing compound, and at least the low molecular weight polyfunctional active hydrogen atom-containing compound is used. A polyurethane elastomer produced by using a low molecular weight polyfunctional active hydrogen atom-containing compound that does not have a quaternary nitrogen atom as a part, and JP-A-58-118.
No. 703, a polyester glycol obtained from an aliphatic dicarboxylic acid and an alkanediol having 6 or more carbon atoms, or a polyester glycol or polycaprolactone glycol having the same repeating unit as the aliphatic glycol, an aliphatic diisocyanate or an aliphatic glycol. Examples thereof include polyurethane elastomers obtained from diisocyanate, organic diamine or hydrazine, or organic acid dihydrazide.

The skin layer can be obtained by applying a solution of polyurethane elastomer by a gravure coating method or a spray method and then drying. As the solvent, for example, N, N-dimethylformamide or isopropanol is used.

In addition, the thickness of the skin layer is usually preferably in the range of 5 to 50 μm in terms of texture and creases. Further, this skin layer may contain various stabilizers such as an ultraviolet absorber and an antioxidant.

Next, as an acid dye for dyeing the epidermis layer, a leveling-type acid dye, a semi-leveling-type acid dye, a milling-type acid dye, 2:
There is a type 1 gold-containing acidic dye, etc., but any one can be used.

In addition, not only the skin layer but also the microporous layer and the base material layer may be dyed with the acid dye in the synthetic leather.

Further, as the reducing agent, for example, hydrosulfite (Na ₂ S ₂ O ₄ ), dechlorin [Zn (OSOCH ₂ OH) ₂ or Zn (OCOCH ₂ OH) OH], Rongalit (NaHSO ₂ · CH ₂ O. 2H
₂ O) and the like, but are not particularly limited.

Further, since the acid dye is extremely easily decolorized by the reducing agent, the concentration of the reducing agent, the solution temperature, the treatment time, and the reduced thickness of the surface portion of the skin layer by the reducing agent are:
For example, it is necessary to stop to the minimum necessary to obtain sufficient adhesion with the adherend such as shoe sole material. The concentration of the reducing agent is usually 0.5 to 5% by weight, preferably 1 to
If the amount is 2% by weight and less than 0.5% by weight, the reduction cleaning removal of the dye becomes insufficient, while if it exceeds 5% by weight, the reducing cleaning is promoted violently and color spots are partially caused.

Further, the solution temperature of the reducing agent is usually 30 to 70 ° C., preferably 40 to 60 ° C., and if the temperature is less than 30 ° C., reducing cleaning proceeds extremely slowly, which is not preferable in terms of work efficiency.
When the temperature exceeds ℃, not only is the alkalinity high and the work environment is not preferable, but also the reduction cleaning easily proceeds to rest and causes color spots, which is not preferable.

Further, the treating time of the reducing agent is usually 3 to 30 minutes, preferably 5 to 15 minutes. If it is less than 3 minutes, the reduction of the surface portion of the skin layer will be insufficient, and for example, an object to be adhered such as a shoe sole material. Good adhesion with and good fastness to wet rubbing cannot be obtained, or migration (dye transfer) is likely to occur at the part where the above-mentioned adherend and the adherend are overlapped, while if it exceeds 30 minutes, the surface of the skin layer The reduction of the parts proceeds too much, and a sufficient dyeing effect of the acid dye cannot be obtained.

It should be noted that the synthetic leather used in the present invention is not limited to the one having the above-mentioned constitution, and may be one having no microporous layer or one having a surface layer consisting of several partial skin layers, for example.

Further, as the method for producing the dermis used in the present invention, the synthetic leather is mainly dyed and then the surface portion of the dyed skin layer is reduced and washed with a reducing agent, but the method is not limited to this. is not. For example, a scaly skin in which an acid dye is added to a composition for forming a skin layer of Akajime, the skin layer is formed using this composition, and then the surface portion of the skin layer is reduced and washed with a reducing agent is used. If you do
It is broadly within the scope of the present invention.

The method for producing a synthetic leather shoe of the present invention, after dyeing with an acid dye, the synthetic leather obtained by reducing and washing is cut and sewn to form the scabbard of the shoe, and the scabbard is hung on the last mold, After that, the last mold in which the skin is suspended is fitted in the side mold and the bottom mold by providing a space for molding the sole, and the material for molding the sole is injected into the gap to injection-mold the sole. However, it is not particularly limited except as specified by the present invention, and a conventional method can be used.

[Action]

The present invention has clarified that the dye molecules are present at a high concentration on the surface of the synthetic leather dyed with an acid dye, and that this does not sufficiently exhibit the adhesiveness with a synthetic resin such as polyvinyl chloride. , Diffuses well into the inside of the leather, and the dye molecules that have been dyed remain as they are, and by removing the dye molecules that hinder the adhesiveness in the vicinity of the surface part, the adhesiveness is improved, and the wet friction fastness is also improved. It is possible to prevent migration.

〔Example〕

Examples of the present invention will be described below, but the present invention is not limited thereto.

Example 1 70% by weight of nylon 6 (1.2 denier, fiber length 51 mm) and heat-shrinkable polyester (2.5 denier, fiber length 5)
Short fiber entangled body (fiber weight, 180
After fixing g / m ² and thickness 1.2 mm with polyvinyl alcohol to form a base material layer, polyurethane elastomer (100% modulus = 45 kg / cm ² , polyethylene butylene adipate and 4,4 ′ diphenylmethane diisocyanate and 1 A polyurethane elastomer consisting of 1,4 butanediol) was impregnated with a solution of 12.5% by weight of N, N-dimethylformamide and then solidified in water to form a microporous layer on the substrate layer.

The weight ratio of fiber to polyurethane resin is 100: 70.
Met.

Furthermore, a polyurethane resin that adheres to polyvinyl chloride on release paper with a leather tie and is easily dyeable (trade name: Sampren, Sanyo Kasei Co., Ltd., 100% modulus = 60k
g / cm ² , 23% by weight of thermal softening point 148 ° C), isopropyl alcohol / toluene / N, N-dimethylformamide = 40/40 /
After applying a 20 (weight ratio) solution and stacking a 25 μm thick skin layer, a 2-pack type polyurethane adhesive (trade name: Rezamin, manufactured by Dai Nippon Seika Co., Ltd.) is applied to a thickness of 40 μm, and the solvent is volatilized. After that, a microporous layer was laminated on the base material layer to obtain a synthetic leather for use in the leather of shoes.

In order to measure the polyvinyl chloride adhesive strength of this product before dyeing, the obtained synthetic leather was stuck in a shoe sole molding die, and a shoe sole material composed mainly of polyvinyl chloride at 197 ° C was injected. . The adhesive strength of the synthetic leather / sole material after cooling was 4.8 kg / cm.

Then, this synthetic leather was dyed by Kayakaran Red BL (2: 1 type gold-containing acidic dye, manufactured by Nippon Kayaku Co., Ltd.) by a conventional method, and then an amylazine (Daiichi Kogyo Pharmaceutical type) aqueous solution (2 g /
l) After thoroughly soaping, 60 g of an aqueous solution of hydrosulfite 2 g / l and caustic soda 1 g / l
It was reduced and washed at ℃ × 10 minutes. Most of the dye on the back surface of the base material layer was decolorized by reducing washing, but the hue of the surface portion of the skin layer was only slightly thinned by reducing washing, and there was almost no difference in appearance.

The adhesive strength of this product with the shoe sole material was measured in the same manner as before dyeing. As a result, it was 4.3 kg / cm, showing extremely good adhesiveness.

Comparative Example 1 The adhesive strength with the sole material of the shoe which was not subjected to reduction cleaning in Example 1 was measured and found to be 0.3 kg / cm.

Example 2 17.5 of a polyurethane elastomer (100% modulus = 43 kg / cm ² ) was placed on a base material layer made of polyester / rayon (weight ratio) = 65/35 mixed spinning single-sided brushed fabric (thickness 0.8 mm).
Wt%, N, N-dimethylformamide solution was applied and then solidified in a 10 wt% N, N-dimethylformamide aqueous solution to form a 0.8 mm thick microporous layer, and then the example By laminating the epidermis layers in the same manner as in No. 1, synthetic leather for wing skin was formed.

Then, it is dyed according to a conventional method using Kayanol Milling Green GW (milling type acid dye), then soaped with an amylazine aqueous solution (2 g / l), and an aqueous solution containing caustic soda 1 g / l and hydrosulfite 2 g / l. Was used as a reducing agent, and reduction cleaning was performed at 60 ° C. for 10 minutes.
The change in the adhesive strength of this product with the shoe sole material before and after washing was 3.8 kg / cm to 3.4 kg / cm, which was hardly reduced.

Comparative Example 2 Although not subjected to reduction washing after dyeing in Example 2, the adhesive strength with the shoe sole material was 0.2 kg / cm, and it was not durable for use as a scab.

〔The invention's effect〕

Synthetic leather shoes obtained by the present invention, the scabbard,
Adhesiveness to synthetic resins in general, especially to sole materials mainly composed of polyvinyl chloride is extremely good, and it is possible to improve fastness to wet friction and to prevent migration (dye transfer). The shoe sole has excellent adhesiveness and less discoloration, and its industrial significance is extremely large.

Claims (1)

[Claims] 1. A synthetic leather obtained by dyeing the surface layer of synthetic leather with an acid dye, and then reducing and washing the surface portion of the surface layer with a reducing agent to cut and sew synthetic leather to form a scabbard of a shoe. Suspend this skin in the last mold, and then place the last mold in which this skin is hung in the side molding and the bottom mold by providing a space for molding the sole, and then in the space for molding the sole, polyvinyl chloride. A method for producing a synthetic leather shoe, which comprises injecting a shoe sole molding material mainly composed of: