JPS63120180A - Production of synthetic leather having anisotropic foamed structure - Google Patents

Abstract

PURPOSE:To obtain a synthetic leather similar to natural leather in flexibility and the property to generate small surface wrinkles upon bending, by forming an anisotropic foamed structure consisting of an upper layer having small cell diameter and a lower layer having large cell size using foaming agents having different particle diameters. CONSTITUTION:A composition containing 100pts.wt. of polyvinyl chloride paste resin, 50-110pts.wt. of a plasticizer, 2-6pts.wt. of a foaming agent (preferably azodicarbonamide, etc.) and a proper amount of a stabilizer (e.g. Ba-Zn stabilizer) is laminated to the surface of a skin layer of a synthetic leather produced by laminating a foamed resin layer and a surface skin layer on a substrate cloth. In the production of the above laminate having an upper and a lower foamed layers, a foaming agent having particle diameter of about 10mum is compounded to the lower layer and a foaming agent having larger particle diameter than the lower layer foaming agent, i.e. about 10-20mum is used in the upper layer. A synthetic leather obtained by this process has an anisotropic foamed structure composed of an upper layer containing cells having small diameter and a lower layer containing cells having larger diameter than the upper layer cells.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to synthetic leather and a method for producing the same.
The foam layer has an anisotropic foam structure consisting of an upper layer in which small diameter cells are formed and a lower layer in which large diameter cells are formed, and therefore, when folded, fine wrinkles occur on the surface. The present invention relates to a synthetic leather that closely resembles natural leather because it is lightweight, flexible, and has an excellent texture, and a method for producing such synthetic leather.

Conventional Technology In general, in order for synthetic leather to have the same feel and appearance as natural leather, it is required to have fine wrinkles on the surface when folded, to be lightweight and flexible, and to have excellent texture. Ru. However, conventionally known synthetic leather,
Since the resin foam layer on the base fabric has homogeneous foam cells and a homogeneous isotropic foam structure, it is difficult to provide both of the above properties at the same time. That is, if the foam cells in the resin foam layer are made larger, the feel of the synthetic leather will improve, but when the synthetic leather is folded, large wrinkles will occur on the surface. On the other hand, if the foam cells in the resin foam layer are made smaller, fine wrinkles will occur when the synthetic leather is folded, but the weight will increase and the feel will be significantly worse.

Φ Therefore, as a result of intensive research in order to solve the above-mentioned problems in conventional synthetic leather, the inventors of the present invention found that the foam layer is divided into an upper layer in which cells with a small diameter are formed and an upper layer in which cells with a large diameter are formed. By forming the resin foam layer with a lower layer in which cells are formed, and by giving the resin foam layer an anisotropic structure, as mentioned above, it is possible to create fine wrinkles on the surface when folded, and at the same time it is lightweight and flexible. The present invention was based on the discovery that it also has an excellent texture.

A 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 fabric. 50 to 1 part of plasticizer per 100 parts by weight of polyvinyl chloride paste resin, respectively.
When forming the upper and lower layers of the foam layer from a formulation containing 10 parts by weight of a blowing agent, 2 to 6 parts by weight of a blowing agent, and an appropriate amount of a stabilizer, as a blowing agent in the formulation for the upper layer, for the lower layer. Using a foaming agent with a larger particle size than the foaming agent in the formulation, an anisotropic resin foam layer consisting of an upper layer in which small-diameter cells are formed and a lower layer in which large-diameter cells are formed is formed. It is characterized by

In the present invention, the cell number density refers to the number of foam cells per 1 crA in the cross section of the foam structure.

According to the present invention, as described above, when forming the upper layer and the lower layer by heating and foaming a composition containing a polyvinyl chloride paste resin, a plasticizer, a stabilizer, and a blowing agent, respectively,
By using a blowing agent in the formulation for the upper layer that has a larger particle size than that in the formulation for the lower layer, when heating and foaming each formulation, the foam cell diameter in the upper layer By making the foam cell diameter smaller and increasing the foam cell diameter in the lower layer, it is possible to obtain synthetic leather having an anisotropic foam structure.

However, in the above, when blowing agents with different particle sizes are blended into the same polyvinyl chloride paste resin and foamed under the same heating conditions, the larger the particle size, the smaller the foam cells formed. means a blowing agent.

In the present invention, the blowing agent is preferably one that decomposes at a relatively high temperature, such as azosicabonamide. As the blowing agent, commercially available products can be used, but in particular, the blowing agent has a decomposition temperature of about 200°C and an average particle size of 4 to 8 μm.
A fine particulate blowing agent of about m is preferred. Such blowing agents are
Usually, in each formulation, 2 to 6 parts by weight are added per 100 parts by weight of polyvinyl chloride paste resin.

In order to obtain synthetic leather having an anisotropic foam structure according to the present invention, for example, a foaming agent with an average particle size of about 10 to 20 μm is added to the formulation for the upper layer, and a blowing agent is added to the formulation for the lower layer. A blowing agent having an average particle size of about 10 μm or less and a smaller average particle size than the blowing agent in the formulation for the upper layer is used.

In the present invention, the polyvinyl chloride paste resin is
have the same degree of polymerization, have the same melt viscosity when foamed using the same blowing agent in the same amount under the same heating conditions,
Refers to a polyvinyl chloride paste resin that provides a foamed structure with the same cell diameter and cell number density; usually the same polyvinyl chloride paste resin is used in the formulation for the top and bottom layers.

Moreover, in the present invention, polyvinyl chloride paste resins having a degree of polymerization of 600 to 3,500 are generally suitably used. Furthermore, a vinyl chloride-vinyl acetate copolymer paste resin is also included in the polyvinyl chloride paste resin, and this can be used alone or together with the polyvinyl chloride paste resin, if necessary.

Similarly, plasticizer refers to a plasticizer that gives the same melt viscosity under the same heating conditions when blended in the same amount in the same polyvinyl chloride paste resin, and is typically used in formulations for the top and bottom layers. The same plasticizer is used in both cases.

In the present invention, as the plasticizer, for example, a phthalate ester plasticizer is preferably used.

Specific examples of such plasticizers include dibutyl phthalate and dioctyl phthalate. Also,
In addition to the above-mentioned phthalate ester plasticizers, epoxy plasticizers may also be used as needed. Such plasticizers are usually used in an amount of 50 to 110 parts by weight based on 100 parts by weight of the polyvinyl chloride base resin.

Furthermore, according to the invention, not only do the particle sizes of the blowing agents in the polyvinyl chloride-based resin formulations for the top and bottom layers differ, as described above, but also fa) a smaller amount of the blowing agent in the formulation for the top layer is A method of blending a plasticizer and blending a larger amount of plasticizer into the blend for the lower layer so that the upper layer has a higher melt viscosity when the blend is heated and melted (tel. A method in which the upper layer has a higher melt viscosity when the formulation is heated and melted by using a polyvinyl chloride-based resin with a higher degree of polymerization and using a polyvinyl chloride-based resin with a lower degree of polymerization in the formulation for the lower layer, tel A method of adjusting the cell diameter and cell number density of a foamed structure by incorporating a small amount of blowing agent in the formulation for the upper layer and a large amount of the blowing agent in the formulation for the lower layer, and (d+ A method in which the upper layer has a larger melt viscosity when the mixture is heated and melted by blending a larger amount of the cell regulator in the blend for the upper layer and a smaller amount of the cell regulator in the blend for the lower layer; It is also possible to combine one or more of these methods with the method of varying the particle size of the blowing agent described above.

However, as mentioned above, the plasticizer used in the above method (al) is the same as that of the same polyvinyl chloride base resin.
When formulating the upper layer, it means a plasticizer that gives the same melt viscosity under the same heating conditions, and when adopting method (a) above, for example, the plasticizer in the formulation for the upper layer is polyvinyl chloride. 50 per 100 parts by weight of paste resin
It is preferred that the plasticizer in the formulation for the lower layer is in the range ~90 parts by weight, especially 60-80 parts by weight.
7 for 100 parts by weight of polyvinyl chloride paste resin
The range is preferably from 0 to 110 parts by weight, particularly from 80 to 100 parts by weight.

When employing method (b) above, for example, the polyvinyl chloride-based resin in the formulation for the top layer is
The polyvinyl chloride base resin in the lower layer formulation preferably has a polymerization degree of about 700 to 1500, and the polyvinyl chloride base resin in the upper layer formulation has a polymerization degree of about 700 to 1500. vinyl pace h
It is preferred to have a degree of polymerization smaller than the degree of polymerization of l/gin.

When employing the above method (C), although not particularly limited, the blowing agent is usually added in an amount of 2 to 4 parts by weight in the formulation for the upper layer, and in the formulation for the lower layer. is 3~
The amount is 6 parts by weight, and is blended in an amount larger than that in the formulation for the upper layer.

In addition, the cell conditioner used in the above method (d) means a cell conditioner that gives the same melt viscosity under the same heating conditions when blended in the same amount with the same polyvinyl chloride base resin, and usually , the same cell conditioner is used in the formulations for the top and bottom layers. This method (d
), for example, the cell conditioner in the formulation for the top layer is polyvinyl chloride paste resin 10
It is preferably 1 to 3 parts by weight relative to 0 parts by weight,
The cell conditioner in the formulation for the lower layer is in a smaller amount than in the formulation for the upper layer and ranges from 0.5 to 100 parts by weight of the polyvinyl chloride paste resin.
Preferably it is 2 parts by weight.

Various cell conditioners are commercially available, and any one can be used. For example, BAP-1 (manufactured by Adeka Argus Chemicals), whose main components are an alkyl methacrylate oligomer, an epoxidized fatty acid glycerin ester, and a solvent, can be suitably used.

Furthermore, since it is generally known that various stabilizers used in polyvinyl chloride-based resins act as decomposition accelerators or inhibitors for blowing agents, appropriate stabilizers should be included in each formulation. This makes it possible to control the foaming of the foaming agent during heating and melting of the compound, thereby facilitating the formation of an anisotropic foam structure. For example, since the Ba-Zn stabilizer accelerates the decomposition of the foaming agent, by incorporating it in a larger amount into the formulation forming the lower layer, the foam cells in the lower layer can be enlarged. It goes like this a
- As a Zn-based stabilizer, for example, a commercially available stabilizer PL-54G made by Adeca Argus Chemical Co., Ltd. whose main components are aromatic carboxylic acid barium salt, aliphatic carboxylic acid zinc salt, and a solvent)
can be preferably used.

If desired, a thickener may also be included in the polyvinyl chloride paste resin formulation. Thickeners are used to increase the viscosity of the sol and improve its applicability when applied onto a base fabric. Various such thickeners are commercially available.

Additionally, the formulation may optionally contain fillers, antioxidants,
It may contain an appropriate amount of ordinary compounding agents such as coloring agents.

The synthetic leather according to the present invention can be produced by, for example, first applying a resin to form a skin layer on a release paper and drying it, and then applying the above-mentioned compositions for the upper layer and lower layer thereon. After coating in the order of the lower layers, it can be obtained by immediately bonding with a base fabric, heating and foaming the mixture, and after cooling, peeling off the release paper. Note that the appropriate heating temperature for the compound is usually about 180 to 220°C.

In the synthetic leather of the present invention obtained in this way, the upper layer has cells with a diameter of 80 to 300 μm formed at a cell number density of 600 to 2000/ctA, and the lower layer has cells with a diameter of 100 to 300 μm. ~800I! m, and cells having a diameter larger than the diameter of the upper layer are formed at a cell number density of 800 to 3000 cells/ant. Preferably, in the upper layer, the cell diameter is substantially 10
0~200μm 1 cell number density 800~1500/C
In the lower layer, the cell diameter is substantially 200 ~
300pm, cell number density 800-1500/ctM
It is.

As described above, the synthetic leather according to the present invention has a foamed layer consisting of five upper layers in which cells of small diameter are formed and a lower layer in which cells of large diameter are formed. Since it has an anisotropic foam structure, fine wrinkles appear on the surface when it is folded, and it is lightweight, flexible, and has an excellent texture, so it closely resembles natural leather. Such synthetic leather according to the present invention is suitable, for example, for covering.

EXAMPLES The present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples in any way.

Example 1 Formulation A below was used for the top layer and Formulation B below for the bottom layer. The number of parts indicates parts by weight.

Compound A Parts Polyvinyl chloride paste resin (7 degrees of polymerization 1650) 100 Dioctyl phthalate 80 Ba-Zn stabilizer FL54 (manufactured by Adeka Argus Chemical ■)
2 Cell conditioner BAP-1 (manufactured by Adeka Argus Chemical) 1 Foaming agent uniform AZ-H? 'I (average particle diameter 14.2 μm
1 Azocicabonamide manufactured by Otsuka Chemical ■ 3 Thickener (
AC-1 manufactured by Shiraishi Kogyo i+1) 4 Compound B ・Polyvinyl chloride paste resin (degree of polymerization 1650) 100 dioctyl phthalate 80 Ba-Zn stabilizer FL54 (manufactured by Adeka Argus Chemical ■)
2 cell conditioner BAP-1 (manufactured by Adeka Argus Chemical)
1 Blowing agent uniform AZL (average particle size 8.0μ
m, azocycarbonamide manufactured by Ogaki Kagaku 01)
3 Thickener (AC-1 manufactured by Shiraishi Kogyo ■)
4 Appropriately colored polyurethane resin (Dainichiseika 0 Kiku, Rezamin 2825LP) was applied to the release paper so that the thickness was 10 μm after drying with a reverse coater.
) and heat-dried at 100°C for 2 minutes, then PV
C sol (compound A) was applied to a thickness of 200 μm using a knife coater, heated at 140° C. for 2 minutes to semi-gel,
Further, PVC sol (compound B) was applied thereon to a thickness of 200 μm using a knife coater, and a base fabric was immediately attached. After heating and 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 100~
150 μm, cell number density 1200/d, lower layer foam cell diameter 200-250 μm 1 cell number density 1000
number/cnl. When this material was folded, it had fine wrinkles on its surface, was lightweight and flexible, and had an excellent texture.

Comparative Example 1 After drying with a reverse coater on release paper, the thickness is 10μ
Apply appropriately colored polyurethane resin (Dainichiseika ■, Rezamin 2825LP) so that the temperature is 100°C.
After heating and drying for 2 minutes at
) with a knife coater to a thickness of 200 μm,
The mixture was heated at 0°C for 2 minutes to form a semi-gel, and the base fabric was immediately attached. Next, the foam was heated and foamed at 200° C. for 1 minute and 30 seconds, and after cooling, the release paper was peeled off.

In the obtained semi-synthetic leather, the entire foam layer is homogeneous,
The foam cell diameter was 100 to 150 μm, and the cell number density was 1200 cells/cd. When folded, this produced fine wrinkles similar to those of natural leather, but lacked flexibility and had a poor texture.

Comparative Example 2 Semi-synthetic leather was obtained in exactly the same manner as in Comparative Example 1, except that the following Compound C was used instead of Compound A.

Blend C Polyvinyl chloride paste resin (degree of polymerization 1650) 100 dioctyl phthalate 80 Ba-Zn stabilizer FL54 (manufactured by Adeka Argus Kagaku Shikiku)
2 cell conditioner BAP-1 (manufactured by Adeka Argus Chemical a)
1. Foaming agent uniform AZL (Azosicarbonamide manufactured by Daijin Kagaku ■) 5. Thickener (Shiraishi Kogyo's type AC-1) 4. This semi-synthetic leather is homogeneous throughout and has a foam cell diameter of 400 to 500.
pm, and the cell number density was 2500 cells/cnt. This was similar to natural leather and was flexible and lightweight, but no fine wrinkles were generated on the surface when it was folded.

Claims (1)

[Claims] (1) In a method for producing synthetic leather in which a resin foam layer and a skin layer are laminated on a base fabric, 50 to 1 part of a plasticizer is added to 100 parts by weight of each polyvinyl chloride paste resin.
When forming the upper and lower layers of the foam layer from a formulation containing 10 parts by weight of a blowing agent, 2 to 6 parts by weight of a blowing agent, and an appropriate amount of a stabilizer, as a blowing agent in the formulation for the upper layer, for the lower layer. Using a foaming agent with a larger particle size than the foaming agent in the formulation, an anisotropic resin foam layer consisting of an upper layer in which small-diameter cells are formed and a lower layer in which large-diameter cells are formed is formed. A method for producing synthetic leather having an anisotropic foam structure.