JPH0686711B2 - Synthetic leather - Google Patents

Description

TECHNICAL FIELD The present invention relates to a synthetic leather in which at least a base material layer and a urethane layer are laminated.

The urethane layer referred to here is a layer including a urethane-based adhesive layer for adhering this urethane layer and a lower layer adjacent thereto.

[Prior Art] Conventionally, a synthetic leather in which at least a base material layer and a urethane layer are laminated is cut and bent into a predetermined shape and used for, for example, a leather skin of a shoe. For the purpose of shape retention, prevention of fraying, and temporary adhesion of bent portions, latex processing is performed to attach latex having adhesiveness to the back surface.

[Problems to be solved by the invention]

By the way, when the back surface of the synthetic leather is subjected to latex processing in this way, the latex permeates into the synthetic leather from the back surface, and then the latex that reaches the urethane layer is the wet cell formed in the urethane layer. And air bubbles (including air bubbles entrapped in the urethane-based adhesive layer when the adhesive is applied), which allows the latex-processed synthetic leather to
When rolled up to ~ 50 m, the wet cell and air bubbles are crushed and fixed by the adhesive action of the latex by wrapping and pressure bonding.Therefore, the depressions are formed macroscopically on the surface of the synthetic leather and the flatness of the back surface is poor. In addition, or when a squeezing pattern is formed on this surface, the squeezing pattern has been changed.

On the other hand, in order to prevent depression formation of the synthetic leather and change of the squeeze, a means for applying a silicone-based resin or a fluorine-based resin to the back surface of the synthetic leather and water-repellently treating it, and then performing a latex treatment was also taken, It was found that when the latex is applied after being subjected to the water repellent treatment in this way, the back surface of the synthetic leather is not adhered by the latex and is easily peeled off.

The present invention has been made on the basis of such a conventional technique, and maintains the original elasticity of the synthetic leather, the flatness of the surface, and the squeezing pattern on the surface without deteriorating the adhesiveness of the latex. It is intended to provide a synthetic leather capable of preventing squeeze change when it is formed.

[Means for solving problems]

That is, the present invention is a synthetic leather in which at least a base material layer and a urethane layer are laminated, and an adhesive latex is attached to the back surface of the base material layer side, in each layer below the urethane layer, or The metal chloride that coagulates the latex is applied to one or more of the specified layers.
The present invention provides synthetic leather characterized by containing 0.01 to 87.5 g / m ² .

Synthetic leather used in the present invention includes, for example, a base material layer made of cloth, a urethane layer laminated thereon, and a surface layer made of a synthetic resin further laminated on the urethane layer if necessary. It is configured.

The synthetic leather is not particularly limited as long as at least a base material layer and a urethane layer are laminated, such as one in which another layer such as a urethane layer is further laminated under the base material layer. .

The base material layer of the present invention is a layer constituting a base material portion of synthetic leather,
A cloth can be used as the material. Examples 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 is impregnated and solidified as a binder. May be.

As the fibers, natural fibers such as cotton, hemp, and wool,
Examples include synthetic fibers (artificial fibers) such as rayon, acetate, nylon, polyester, polyacrylonitrile, and vinylon. In the case of synthetic fibers, not only single-spun fibers but also these or a mixture of these with other polymers or Composite spun fibers can also be used, and those composed of heat-resistant fibers such as nylon 6,6, polyethylene terephthalate, rayon, and cotton are particularly preferable.

When mixed or composite spun fibers are used, at least one of the plurality of polymers constituting the fibers is extracted and removed at any stage, or
Alternatively, it is preferable to employ a method of performing a division treatment between polymers.

Further, as the binder optionally used in the base material layer, any binder generally used for synthetic leather can be used, and examples thereof include polyurethane elastomer, polyvinyl chloride, natural rubber, and synthetic rubber. used. These binders are adhered to a sheet mainly composed of fibers by a method such as an impregnation method or a coating method in the form of a solution or an emulsion, and are solidified by a dry method or a wet method. It is preferable to use a porous structure having the above because the quality such as texture and tear strength is excellent.

The thickness of this substrate layer is usually 0.3 to 3.0 mm, preferably 0.
5 to 2.0 mm.

The urethane layer of the present invention is a layer made of a polyurethane elastomer generally used as a urethane layer of synthetic leather, and includes foamed and unfoamed ones.

The polyurethane elastomer used in this urethane layer has a nitrogen content of 3 to 3 based on diisocyanate.
It is preferably 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, methacrylic acid resin, vinyl chloride-vinyl acetate copolymer and the like can also be mixed.

It is preferable that the urethane layer has a porous structure in terms of folding, texture and the like. As a method of forming this urethane layer,
The base material layer is coated with a solution of the above-mentioned polyurethane elastomer-based polymer, and then the polymer is solidified by immersing in a solution having an affinity for a solvent but no affinity for the polymer. The method is preferred.

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

Further, if necessary, the surface layer laminated on the urethane layer is a layer containing a polyurethane elastomer as a main raw material.

The surface of this surface layer may be subjected to fine embossing in order to bring out a feeling of high quality.

The polyurethane elastomer used for this surface layer is not particularly limited, but for example, Japanese Patent Publication No. 61-
Proposed as a polyurethane film layer in Japanese Patent No. 43471, polyether-based polyurethane using polytetramethylene glycol as a polyol component, or polycarbonate polyester-based polyurethane, and the like, but particularly a polyurethane elastomer having a softening point of 130 ° C. or higher. 3,3'-Dimethyldiphenylmethane-4,4'-
A polyurethane elastomer containing diisocyanate as the diisocyanate component is preferred.

In this polyurethane elastomer, in addition to a filler, a stabilizer, a pigment, a dye, a foaming agent, etc., if necessary, a polymer having good compatibility in a solution state, such as polyvinyl chloride,
It is also possible to mix polyvinyl acetate, polyvinyl formal, methacrylic acid resin, vinyl chloride-vinyl acetate copolymer and the like.

The surface layer is formed, for example, by applying a solution of the polyurethane elastomer to the surface of a release paper (not shown) that has been embossed by a doctor knife or a spray method, and then applying an adhesive solution in the same manner. After that, it can be obtained by drying, and as the solvent, for example, N, N-dimethylformamide, methyl ethyl ketone, isopropanol and the like are used.

The thickness of this surface layer is usually 2 to 100 μm, preferably 4 to 50 μm.

The synthetic leather of the present invention contains a metal chloride for coagulating latex in each layer below the urethane layer or in one or more predetermined layers.

The layer below the urethane layer is usually a synthetic leather in which the urethane layer and the surface layer are sequentially laminated with the base material layer as the lowermost layer as described above. Further, a urethane layer, a synthetic resin coating layer, or the like may be laminated in some cases. At this time, it means all the layers below the urethane layer, or any one layer or several layers thereof.

The latex is a kind of adhesive that is attached to the back surface of the synthetic leather to maintain the shape of the synthetic leather, prevent fraying, and temporarily bond the bent portion.

Examples of the latex include natural rubber and styrene-
Butadiene rubber, acrylonitrile-butadiene rubber,
Chloroprene rubber, methyl methacrylate-butadiene copolymer, polybutadiene rubber, polyisobutylene rubber, urethane rubber, acrylic rubber, vinyl rubber,
Examples of the latex include other synthetic rubbers, and natural rubber latex is preferable in terms of economy, storage stability, film forming property, and film strength.

Further, the metal chloride, by containing each layer below the urethane layer of the synthetic leather, or a predetermined layer or layers, permeation of the latex attached to the synthetic leather to the leather, by this metal chloride The coagulation action of the latex prevents it from advancing beyond a predetermined layer.

The metal chlorides include calcium chloride, zinc chloride,
Examples thereof include lithium chloride, lead chloride, thorium chloride, iron chloride, and other metal chlorides, as well as hydrates of these metal chlorides, and calcium chloride is preferable from the viewpoint of economic efficiency and easy handling. The metal chloride is usually used as an aqueous solution, or may be partially added with alcohol before use.

The concentration of the metal chloride aqueous solution at this time is usually 0.5 to 25% by weight, preferably 1 to 15% by weight. If the concentration is less than 0.5% by weight, the effect of the present invention cannot be obtained, while if it exceeds 25% by weight. The adhesion between the latex and the base material layer may be poor, and the texture of the synthetic leather may deteriorate.

In addition, the amount of metal chloride attached to synthetic leather is 1
An aqueous solution per m ² is usually 2-350 g, preferably 5-
It is 250 g, and the effect of the present invention cannot be obtained with less than 2 g, while
If it exceeds 350 g, the adhesion between the latex and the base material layer may become poor, and the texture of the synthetic leather may deteriorate.

As a method of incorporating this metal chloride into the synthetic leather,
For example, gravure processing for attaching a metal chloride aqueous solution to the back surface of the synthetic leather, dipping processing for immersing the synthetic leather in the metal chloride aqueous solution, and the like can be mentioned, but the invention is not necessarily limited thereto.

A specific example of adding metal chloride to synthetic leather is as follows. For example, the method of adding it to wet synthetic leather is as follows: coating of the base material layer with a polyurethane elastomer solution → desolvation in a coagulation bath → squeezing with mangle → Gravure processing (or dipping processing) with an aqueous metal chloride solution → drying, impregnation of the base material layer with polyurethane elastomer solution → desolvation in a coagulation bath → squeezing with mangle → drying → recoating of the polyurethane elastomer solution on the surface side →
Re-desolventization in coagulation bath → re-squeezing with mangle → gravure (or dipping) with metal chloride aqueous solution → re-drying, coating with urethane chloride solution containing metal chloride on base material layer → coagulation bath Among them, there are methods such as desolvation → squeezing with mangle → drying.

In addition, the method of containing metal chloride in dry foam synthetic leather is
For example, gravure process (or dipping process) of base material layer with aqueous metal chloride solution → drying → coating of polyurethane elastomer solution containing foaming agent on base material layer → heating
Examples of the method include foaming.

Further, the method for incorporating metal chloride into the unfoamed dry synthetic leather is, for example, gravure processing (or dipping processing) of the base material layer with an aqueous solution of metal chloride → drying → polyurethane elastomer on the base material layer with a urethane adhesive. And a polyurethane elastomer containing a metal chloride is laminated on the base material layer via an adhesive.

Furthermore, as a method for incorporating metal chloride into the product-processed synthetic leather, for example, a method such as gravure (or dipping) with an aqueous solution of metal chloride into the product-processed synthetic leather → drying can be mentioned.

When performing gravure processing with a metal chloride, the processed surface is the back surface of the synthetic leather.

[Action]

In the synthetic leather of the present invention, the metal chloride is one coagulant that coagulates the latex, so that the latex attached to the back surface of the synthetic leather can penetrate up to the urethane layer and the layers containing the metal chloride. However, the upper layer adjacent to this layer coagulated in the layer containing the metal chloride does not penetrate the latex. Therefore, when pressing the leather in the manufacturing process of synthetic leather products, the wet cells and air bubbles (including air bubbles trapped in the urethane adhesive layer when applying the adhesive) formed in the urethane layer are compressed at one end. Although it is crushed by, it recovers to its original shape when the compression is released, so the elasticity inherent in the synthetic leather can be maintained, and a depression is formed on the surface of the synthetic leather macroscopically. Does not deteriorate in flatness and does not cause a diaphragm change when the diaphragm pattern is formed on the surface.

〔Example〕

Examples of the present invention will be described below, but the present invention is not limited to these examples.

In the following examples and comparative examples, the latex collapse resistance of the synthetic leather surface, the adhesion between the latex and the base material layer, and the feel were determined by the following methods.

That is, the latex collapse resistance is as follows: Natural rubber latex (solid content concentration 60% by weight) per 1 m ² on the back surface of synthetic leather
200g knife coat, heat dry at 90 ° C for 10 minutes, then
After air-drying for 30 minutes, the presence or absence of depression on the surface of the synthetic leather was evaluated. ◎ indicates no depression, ○ indicates extremely slight depression, △ indicates slight depression, and × indicates depression.

Further, the adhesion between the latex and the base material layer, after bonding the back surface and the back surface of the obtained synthetic leather, it is pressed from the surface of the synthetic leather with a hand roller, and then the back surface and the back surface of the synthetic leather. Was opened 180 degrees to determine the adhesiveness between the latex and the base material layer, and ◎ indicates strong adhesiveness, ○
Indicates good adhesion, Δ indicates slightly poor adhesion, and x indicates poor adhesion.

Further, the texture is determined by the feel of a plurality of persons judging synthetic leather, ⊚ indicates no change in texture, ◯ indicates a very slight change, Δ indicates a slight change, and x indicates a change.

Examples 1 to 2 Polyester / rayon (weight ratio) = 65/35 on a base material layer made of a blended fabric, a polyurethane elastomer solution (solid content concentration 16% by weight) was coated at 1 kg / m ^{2 and} desolvated in water for 10 minutes. After that, the solution was squeezed with a mangle and impregnated with 300 g of a solution containing 5% by weight or 25% by weight of calcium chloride aqueous solution per m ² , and then dried by heating at 100 ° C. for 5 minutes to obtain a wet base.

On the other hand, a polyurethane elastomer solution (solid content concentration 20% by weight) was applied onto a release body with a knife coat of 100 g per m ^{2 and} dried by heating at 100 ° C. for 2 minutes, followed by a urethane adhesive (solid content concentration 30% by weight). Was coated with 100 g per 1 m ^{2 by a} knife coat to prepare a surface layer base.

Next, the wet base and the surface layer base were bonded together, dried by heating at 100 ° C. for 5 minutes, and then the release body was peeled off to obtain a synthetic leather. Table 1 shows the results of determining the latex collapse resistance, the adhesion between the latex and the base material layer, and the feel using this synthetic leather.

Comparative Example 1 Synthetic leather was obtained using the wet base of Example 1 which was not impregnated with the calcium chloride aqueous solution.

The results of judging the latex collapse resistance, the adhesiveness between the latex and the base material layer, and the feel using this synthetic leather are shown in Table 1.
Shown in the table.

Example 3 One side of a base material layer composed of a polyester / cotton (weight ratio) = 50/50 blend was gravure coated with 6 wt% calcium chloride aqueous solution at 50 g / m ^{2 and} dried by heating at 100 ° C. for 5 minutes. A base material layer containing calcium chloride was obtained.

On the other hand, the polyurethane resin solution (solids content 20%
(% By weight) is coated with 80 g of knife per 1 m ² and 2 at 100 ° C.
After heating and drying for 1 minute, a urethane adhesive (solid content concentration 30% by weight) was further applied with a knife coat of 120 g per 1 m ² , and then this was attached to the non-gravure coated surface of the base layer treated with calcium chloride, and 100 After heating and drying at 5 ° C. for 5 minutes, the release body was peeled off to obtain a synthetic leather.

The results of judging the latex collapse resistance, the adhesion between the latex and the base material layer, and the feel using this synthetic leather
Shown in the table.

Comparative Example 2 Synthetic leather was obtained by using the wet base of Example 3 which was not impregnated with the calcium chloride aqueous solution.

The results of judging the latex collapse resistance, the adhesion between the latex and the base material layer, and the feel using this synthetic leather
Shown in the table.

[Effects of the Invention] The present invention provides a synthetic leather in which at least a base material layer and a urethane layer are laminated in this manner, each layer below the urethane layer, or a metal chloride for coagulating latex in a predetermined layer or layers. Since it is contained, it is possible to maintain the flatness of the surface without reducing the adhesiveness of the latex while maintaining the original elastic force of the synthetic leather, and to prevent the squeezing change when a squeezing pattern is formed on this surface. The effect of being able to be obtained is obtained.

Claims (1)

[Claims] 1. A synthetic leather obtained by laminating at least a base material layer and a urethane layer, and adhering latex having adhesive property to the back surface of the base material layer, the synthetic leather being in each layer below the urethane layer or in those layers. 0.01 to 8 metal chlorides that coagulate the latex are added to one or more of the layers.
Synthetic leather characterized by containing 7.5 g / m ² .