JPH0670306B2 - Method for producing synthetic leather having anisotropic foam structure - Google Patents

Description

TECHNICAL FIELD The present invention relates to a synthetic leather and a method for producing the same, and more specifically,
The foam layer has an anisotropic foam structure composed of an upper layer in which cells having a small diameter are formed with a cell number density and a lower layer in which cells with a large diameter are formed with a large cell number density, and, TECHNICAL FIELD The present invention relates to a synthetic leather that closely resembles natural leather because it has fine wrinkles on the surface when folded, is lightweight and flexible, and has an excellent texture, and a method for producing such synthetic leather.

2. Description of the Related Art Generally, synthetic leather is required to have fine wrinkles on the surface when it is bent, to be light and flexible, and to have a good feel in order to have the same feel and appearance as natural leather. It However, conventionally known synthetic leather is
Since the resin foam layer on the base cloth has a uniform foam cell and a uniform isotropic foam structure, it is difficult to have both of the above properties at the same time. That is, if the foamed cells in the resin foam layer are made larger, the texture of the synthetic leather becomes better, but when the synthetic leather is bent, large wrinkles occur on the surface. On the other hand, if the foamed cells in the resin foam layer are made small, when the synthetic leather is bent, fine wrinkles are generated, but the weight increases, and the texture is significantly deteriorated.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The inventors of the present invention have conducted extensive studies to solve the above-mentioned problems in conventional synthetic leather, and as a result, cells having a small diameter have been formed in a foam layer with a small cell number density. By forming from the upper layer and the lower layer in which the cells of large diameter are formed with a large cell number density, and by providing the resin foam layer with an anisotropic structure, as described above, the The present invention has been completed by finding that fine wrinkles can be generated, and at the same time, it is light and flexible and has excellent texture.

Means for Solving the Problems The first method for producing a synthetic leather having an anisotropic foam structure according to the present invention is a method for producing a synthetic leather in which a resin foam layer and a skin layer are laminated on a base cloth. In 100 parts by weight of polyvinyl chloride paste resin, an upper layer of a foam layer is formed from a mixture containing 50 to 110 parts by weight of a plasticizer, 2 to 4 parts by weight of a foaming agent and an appropriate amount of a stabilizer, and polychlorinated. 50 to 110 parts by weight of a plasticizer and 3 to 6 parts by weight of a foaming agent to 100 parts by weight of a vinyl paste resin, and a stabilizer in an appropriate amount and a larger amount than the foaming agent in the composition for the upper layer are used. The lower layer of the foam layer is formed from the compound containing it and has a diameter of substantially 10
An upper layer in which cells of 0 to 300 μm are formed at a cell number density of 600 to 1200 cells / cm ² and a cell having a diameter of 300 to 800 μm and a diameter larger than that of the upper layer are cells. It is characterized in that a resin foam layer comprising a lower layer formed at a number density of 1000 to 3000 pieces / cm ² is formed.

The second method for producing synthetic leather having an anisotropic foam structure according to the present invention is a method for producing synthetic leather in which a resin foam layer and a skin layer are laminated on a base cloth, and a polyvinyl chloride paste is used. Plasticizer 50 to 110 per 100 parts by weight of resin
Polyvinyl chloride paste having a lower degree of polymerization than a polyvinyl chloride paste resin for forming the upper layer of the foam layer from a composition containing 1 part by weight, 2 to 4 parts by weight of a foaming agent, and an appropriate amount of a stabilizer. 50 to 110 parts by weight of a plasticizer and 3 to 6 parts by weight of a foaming agent to 100 parts by weight of a resin, and contains a stabilizer in an amount larger than that of the foaming agent in the composition for the upper layer, and an appropriate amount. By forming the lower layer of the foam layer from the compound, cells with a diameter of 100-300 μm are substantially
An upper layer formed at 600 to 1200 cells / cm ² and a cell having a diameter of 300 to 800 μm and a diameter larger than the diameter of the upper layer have a cell number density of 1000 to 3000 cells / cm ^2. It is characterized in that a resin foam layer composed of the lower layer formed in (1) is formed.

In the present invention, the cell number density refers to the number of foam cells per cm ^{2 in} the cross section of the foam structure.

According to the present invention, as described above, a polyvinyl chloride paste resin, a plasticizer, and a stabilizer containing a predetermined amount of a foaming agent together with a foaming agent as an upper layer by heat foaming, polyvinyl chloride paste resin, a plasticizer, A formulation containing a larger amount of a foaming agent together with a stabilizer is heated and foamed to form a lower layer, and thus, by varying the amount of the foaming agent in the formulation, the foaming agent causes a small amount in the upper layer. By forming cells having a large diameter and forming cells having a large diameter in the lower layer, a synthetic leather having an anisotropic foam structure can be obtained.

However, in the above, the foaming agent means a foaming agent having the same particle size and the same expansion ratio under the same heating condition, and usually, the composition for the upper layer and the composition for the lower layer. The same foaming agent is used.

As the foaming agent, one that decomposes at a relatively high temperature is preferable, and for example, azodicarbonamide is preferable. As the foaming agent, a commercially available product can be used, but a particulate foaming agent having a decomposition temperature of about 200 ° C. and an average particle diameter of about 3 to 9 μm is particularly preferable. Such a foaming agent may be added to the formulation for the upper layer in an amount of 2 per 100 parts by weight of polyvinyl chloride paste resin.
˜4 parts by weight, 3 to 6 parts by weight in the formulation for the lower layer, and more than the amount in the formulation for the upper layer.

In the present invention, as the polyvinyl chloride paste resin, those having a polymerization degree of 600 to 3500 are usually preferably used. A vinyl chloride-vinyl acetate copolymer paste resin is also included in the polyvinyl chloride paste resin, which may be used alone or in combination with the polyvinyl chloride paste resin in place of the polyvinyl chloride paste resin.

In the present invention, as the plasticizer, for example, a phthalic acid ester plasticizer is preferably used. Specific examples of such plasticizers include dibutyl phthalate and dioctyl phthalate. Further, as the plasticizer, in addition to the phthalate ester-based one, an epoxy-based plasticizer is also used. Such a plasticizer is usually used in the range of 50 to 110 parts by weight with respect to 100 parts by weight of the polyvinyl chloride paste resin.

Further, according to the present invention, as described above, not only the amount of the foaming agent in the polyvinyl chloride paste resin composition for the upper layer and the lower layer is made different, but (a) a small amount of plasticizer is added to the composition for the upper layer. A method of allowing the upper layer to have a higher melt viscosity when the composition is heated and melted by blending an agent and a larger amount of a plasticizer into the formulation for the lower layer, (b) to the formulation for the upper layer By using a higher degree of polymerization polyvinyl chloride paste resin and a lower degree of polymerization polyvinyl chloride paste resin in the formulation for the lower layer, a higher melt viscosity is obtained in the upper layer when the formulation is heated and melted. (C) by adding a large amount of a cell regulator to the composition for the upper layer and adding a small amount of the cell regulator to the composition for the lower layer, At times to provide the upper layer with a higher melt viscosity, and (d) incorporating a smaller particle size blowing agent into the formulation for the upper layer and a larger particle size blowing agent into the formulation for the lower layer. Therefore, one or more of the method of forming a foam cell having a larger diameter in the lower layer when the foaming agent is foamed can be combined with the method of varying the amount of the foaming agent.

However, the plasticizer used in the above method (a) means a plasticizer that gives the same melt viscosity under the same heating conditions when the same amount of the same polyvinyl chloride paste resin is mixed, and is usually the same as the upper layer. In the formulation for the lower layer,
The same plasticizer is used. When this method (a) is adopted, for example, the plasticizer in the formulation for the upper layer is 50 to 90 parts by weight, particularly 60 to 80 parts by weight, based on 100 parts by weight of the polyvinyl chloride paste resin. It is preferably in the range, and the plasticizer in the formulation for the lower layer is 70-110 per 100 parts by weight of polyvinyl chloride paste resin.
It is preferably in the range of 80 parts by weight, especially 80 to 100 parts by weight.

When employing the above method (b), for example, the polyvinyl chloride paste resin in the formulation for the upper layer is
It is preferable to have a polymerization degree of about 00 to 3000, the polyvinyl chloride paste resin in the formulation for the lower layer is about 700 to 1500, and the polyvinyl chloride paste resin in the formulation for the upper layer. It is preferable to have a degree of polymerization smaller than that of.

The cell conditioner used in the above method (c) is the same polyvinyl chloride paste resin when mixed in the same amount,
It means a cell conditioner that gives the same melt viscosity under the same heating conditions, and usually the same cell conditioner is used in the formulations for the upper and lower layers. When this method (c) is adopted, for example, the cell conditioner in the formulation for the upper layer is preferably 1 to 3 parts by weight with respect to 100 parts by weight of the polyvinyl chloride paste resin, and for the lower layer. It is preferable that the amount of the cell conditioner in the above-mentioned formulation is smaller than that in the formulation for the upper layer and is 0.5 to 2 parts by weight based on 100 parts by weight of the polyvinyl chloride paste resin.

Various cell regulators are commercially available, and any one can be used. For example, BAP-1 (manufactured by Adeka Argus Chemical Co., Ltd.) containing an alkyl methacrylate oligomer, an epoxidized fatty acid glycerin ester and a solvent as main components can be preferably used.

Further, when the method (d) is adopted, a foaming agent having an average particle size of about 3 to 6 μm is usually contained in the composition for the upper layer, and an average particle size of about 5 to 9 μm is contained in the composition for the lower layer. And a blowing agent having a larger average particle size than the blowing agent in the formulation for the upper layer is used, respectively. The blending amount of the foaming agent and the average particle size are appropriately selected according to the purpose of the present invention.

Furthermore, it is generally known that various stabilizers used in polyvinyl chloride paste resins act as decomposition accelerators or inhibitors of foaming agents, so it is necessary to add an appropriate stabilizer to each formulation. This makes it possible to control the foaming of the foaming agent during heating and melting of the composition and facilitate the formation of the anisotropic foamed structure. For example, since the Ba-Zn-based stabilizer accelerates the decomposition of the foaming agent, it is possible to increase the size of the foam cells in the lower layer by adding a larger amount to the composition forming the lower layer. As such a Ba-Zn stabilizer, for example, aromatic carboxylic acid barium salt,
A commercially available stabilizer FL-54 (manufactured by Adeka Argus Chemical Co., Ltd.) containing an aliphatic carboxylic acid zinc salt and a solvent as main components can be preferably used.

In the present invention, a thickener may be added to the polyvinyl chloride paste resin composition, if necessary. The thickener is used to increase the sol viscosity and to improve the coatability when applied on the base fabric. Various such thickeners are commercially available.

In addition, the formulation may optionally include fillers, antioxidants,
It may contain an appropriate amount of a usual compounding agent such as a coloring agent.

The synthetic leather according to the present invention may be prepared, for example, by first coating a release paper with a resin for forming a skin layer, drying the resin, and then applying a composition for the upper layer and the lower layer as described above to the upper layer and It can be obtained by applying in the order of the lower layer, immediately laminating with the base fabric, heat-foaming the composition, cooling, and peeling off the release paper. Incidentally, the heating temperature of the compound is usually appropriate at about 180 to 220 ° C.

In the synthetic leather according to the present invention thus obtained, the upper layer has a cell number density of 100 to 300 μm.
The cells are formed at 600 to 1200 cells / cm ² , the lower layer has a diameter of 300 to 800 μm, and the cells having a diameter larger than that of the upper layer have a cell number density of 1000 to 3000 cells / cm. It is formed by ² . Preferably, in the upper layer, the cell diameter is substantially 150 to 250 μm, and the cell number density is 800 to 1000 cells /
cm ² and, in the lower layer, the cell diameter is substantially 400 to 70.
The cell density is 0 μm and the cell number density is 2000 to 3000 cells / cm ² .

As described above, in the synthetic leather according to the present invention, the foam layer has the upper layer in which the cells having the small diameter are formed with the small cell number density, and the cells with the large diameter are formed with the large cell number density. Since it has an anisotropic foam structure consisting of a lower layer
When folded, it has fine wrinkles on the surface, is light and flexible, and has a good texture, so it is very similar to natural leather. The synthetic leather according to the present invention is suitable, for example, as a cover.

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

Example 1 The following Formulation A was used for the upper layer and the following Formulation B was used for the lower layer. The numbers of parts indicate parts by weight.

The thickness is 10 μm after being dried on a release paper with a reverse coater.
Is coated with a moderately colored polyurethane resin (Resamine 2825LP from Dainichiseika Co., Ltd.) and heat-dried at 100 ° C. for 2 minutes, and then PVC sol (formulation A) is 200 μm thick with a knife coater. Coating, heat at 140 ° C for 2 minutes to semi-gelate, and then PVC sol (Compound B)
Was applied to a thickness of 200 μm with a knife coater, and a base cloth was immediately attached. After heat-foaming at 200 ° C. for 1 minute and 30 seconds and cooling, the release paper was peeled off.

The obtained semi-synthetic leather has an upper layer foam cell diameter of 200 to 250.
The cell number density was 1000 cells / cm ² , the foamed cell diameter of the lower layer was 400 to 500 μm, and the cell number density was 2500 cells / cm ² . This is because when it is bent, fine wrinkles are generated on the surface,
It was lightweight and flexible, and had an excellent texture.

Example 2 The following formulation C was used for the upper layer and the following formulation D was used for the lower layer. The numbers of parts indicate parts by weight.

Using these blends, semi-synthetic leather was obtained in the same manner as in Example 1. This semi-synthetic leather has an upper layer foam cell diameter of 150 to 200 μm and a cell number density of 800 to 1000 cells / cm ² ,
Lower layer foam cell diameter is 500-600μm, cell number density 2500-28
It was 00 pieces / cm ² . When it was bent, it had fine wrinkles on the surface, was light and flexible, and had an excellent texture.

Example 3 The following formulation B was used for the upper layer and the following formulation F was used for the lower layer. The numbers of parts indicate parts by weight.

Using these blends, semi-synthetic leather was obtained in the same manner as in Example 1. In this semi-synthetic leather, the upper layer had a foam cell diameter of 200 to 250 μm and the cell number density was 1000 cells / cm ² , and the lower layer had a foam cell diameter of 500 to 700 μm and the cell number density was 2800 cells / cm ² . When it was bent, it had fine wrinkles on the surface, was light and flexible, and had an excellent texture.

Example 4 The same formulation A as in example 1 was used for the upper layer and the following formulation G was used for the lower layer.

Using these blends, semi-synthetic leather was obtained in the same manner as in Example 1. In this semi-synthetic leather, the upper layer has a foam cell diameter of 200 to 250 μm and the cell number density is 1000 cells / cm ² , and the lower layer has a foam cell diameter of 500 to 700 μm and a cell number density of 2800.
It was the number of pieces / cm ² . When it was bent, it had fine wrinkles on the surface, was light and flexible, and had an excellent texture.

Comparative Example 1 The thickness was 10 μm after being dried on a release paper with a reverse coater.
Is coated with a moderately colored polyurethane resin (Resamine 2825LP from Dainichiseika Co., Ltd.) and heat-dried at 100 ° C. for 2 minutes, and then PVC sol (formulation A) is 200 μm thick with a knife coater. Then, it was heated at 140 ° C. for 2 minutes to be semi-gelled, and the base cloth was immediately attached. Then 20
After heat-foaming at 0 ° C. for 1 minute and 30 seconds and cooling, the release paper was peeled off.

The obtained semi-synthetic leather has a uniform foam layer,
The foamed cell diameter was 200 to 250 μm, and the cell number density was 1000 cells / cm ² . When it was bent, it had fine wrinkles similar to those of natural leather, but lacked in flexibility and had poor texture.

Comparative Example 2 A semi-synthetic leather was obtained in exactly the same manner as Comparative Example 1 except that the compound B was used in place of the compound A in the comparative example 1. This semi-synthetic leather was homogeneous in its entirety and had a foam cell diameter of 400 to 500 μm and a cell number density of 2500 cells / cm ² . It was flexible and lightweight, similar to natural leather, but did not have fine wrinkles on the surface when folded.

Comparative Example 3 In Comparative Example 1, instead of the compound A, the compound F or G was used.
Semi-synthetic leather was obtained in exactly the same manner as in Comparative Example 1 except that was used. All of these semi-synthetic leathers are homogeneous and have a foam cell diameter of 500-700 μm and a cell number density of 2800.
It was / cm ² . It was flexible and lightweight, similar to natural leather, but did not have fine wrinkles on the surface when folded.

Claims (2)

[Claims] 1. A method for producing a synthetic leather comprising a resin foam layer and a skin layer laminated on a base fabric, wherein 50 to 110 parts by weight of a plasticizer and 100 parts by weight of a polyvinyl chloride paste resin and a foaming agent are used. An upper layer of a foam layer is formed from a mixture containing 2 to 4 parts by weight and an appropriate amount of a stabilizer, and 50 to 110 parts by weight of a plasticizer and 3 to 6 parts by weight of a foaming agent to 100 parts by weight of polyvinyl chloride paste resin. Part, and forming a lower layer of the foam layer from a composition containing a larger amount of the stabilizer than the foaming agent in the composition for the upper layer, and an appropriate amount of the stabilizer, and having a diameter of substantially 10
An upper layer in which cells of 0 to 300 μm are formed at a cell number density of 600 to 1200 cells / cm ² and a cell having a diameter of 300 to 800 μm and a diameter larger than that of the upper layer are cells. A method for producing synthetic leather having an anisotropic foam structure, which comprises forming a resin foam layer comprising a lower layer having a number density of 1000 to 3000 pieces / cm ² . 2. A synthetic leather manufacturing method comprising a resin foam layer and a skin layer laminated on a base fabric, wherein 50 to 110 parts by weight of a plasticizer and 100 parts by weight of a polyvinyl chloride paste resin and a foaming agent are used. An upper layer of a foam layer is formed from a composition containing 2 to 4 parts by weight and an appropriate amount of a stabilizer, and 100 parts by weight of a polyvinyl chloride paste resin having a degree of polymerization smaller than that of the polyvinyl chloride paste resin for the upper layer is formed. For plasticizer 50
˜110 parts by weight, blowing agent 3 to 6 parts by weight, and forming a lower layer of the foam layer from a formulation containing a greater amount of stabilizer than the blowing agent in the formulation for the upper layer, and an appropriate amount. And the cell number density is 600 to 1
An upper layer formed with 200 pieces / cm ² and a diameter of 300-
Another feature is that a resin foam layer is formed which is a lower layer having a cell number density of 1000 to 3000 cells / cm ² and having a diameter of 800 μm and larger than the diameter of the upper layer. A method for producing synthetic leather having an anisotropic foam structure.