JPS63120179A - 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 a foamed resin layer of a synthetic leather in a manner to form an anisotropic foamed structure composed of an upper layer having small cell size and cell number density and a lower layer having large size and density of the cell. 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 paste resin having a polymerization degree of 1,000-3,000 is used in the upper layer and a resin having a polymerization degree of about 700-1,500 is used in the lower layer. A synthetic leather obtained by this process has an anisotropic foamed structure composed of an upper layer containing cells having diameter of 100-300mum at a number density of 600-2,000 piece/cm<3> and a lower layer containing cells having larger diameter than the upper layer cells, i.e. 200-800mum at a number density of 1,000-3,000 piece/cm<3>.

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. be done. 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.

Problems to be Solved by the Invention Therefore, as a result of intensive research in order to solve the above-mentioned problems in conventional synthetic leather, the inventor 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.

Means for Solving the Problems The 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 foamed resin layer and a skin layer are laminated on a base fabric. 50 to 1 part plasticizer per 100 parts by weight of 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 appropriate amounts of stabilizers and thickeners, polyvinyl chloride in the formulation for the upper layer is used. As the paste resin, a polyvinyl chloride paste resin having a higher degree of polymerization than the polyvinyl chloride paste resin in the formulation for the lower layer is used, and cells with a diameter of 100 to 300 μm have a cell number density of 600 to 15.
00 pieces/cnl, and cells having a diameter of substantially 200 to 800 μm and larger than the diameter of the upper layer have a cell number density of 1000 to 3000.
It is characterized by forming a resin foam layer consisting of a lower layer having a thickness of 1.2 cm/cm2.

In the present invention, the cell number density means l cfl! in the cross section of the foam structure. Refers to the number of foam cells per hit.

According to the present invention, as described above, when forming the foamed structures of the upper layer and the lower layer by heating and foaming a composition containing a polyvinyl chloride pear resin, a plasticizer, a stabilizer, and a blowing agent, respectively, the above-mentioned The respective formulations are heated and foamed by using a polyvinyl chloride paste resin with a higher degree of polymerization as the polyvinyl chloride paste resin in the formulation for the upper layer than the polyvinyl chloride paste resin in the formulation for the lower layer. The melt viscosity of the formulation is made larger in the upper layer and smaller in the lower layer, thus causing the foaming agent to form small diameter cells in the upper layer and large diameter cells in the lower layer, resulting in anisotropy. Synthetic leather having a foam structure can be obtained.

In the present invention, polyvinyl chloride paste resins having a degree of polymerization in the range of 600 to 3500 are generally suitable, and are appropriately selected and used. The polyvinyl chloride paste resin in the formulation for the lower layer preferably has a degree of polymerization of about 1000 to 3000, and the polyvinyl chloride paste resin in the formulation for the lower layer preferably has a degree of polymerization of about 700 to 1.
It is necessary to have a degree of polymerization of the order of 500 and less than that of the polyvinyl chloride paste resin in the formulation for the upper layer.

In the present invention, a vinyl chloride-vinyl acetate copolymer base resin is also included in the polyvinyl chloride paste resin, and this may be used alone in place of the polyvinyl chloride paste resin, or together with the polyvinyl chloride paste resin, as necessary. used.

In the present invention, plasticizer means a plasticizer that gives the same melt viscosity when blended in the same amount with the same polyvinyl chloride paste resin, and usually the same plasticizer is used in the formulation for the upper layer and the lower layer. agent is used.

As the plasticizer, for example, agents other than phthalate esters are preferably used. Specific examples of such plasticizers include dibutyl phthalate and dioctyl phthalate. In addition to the above phthalate ester plasticizers, epoxy plasticizers may also be used as needed. Such plasticizers are typically used in polyvinyl chloride paste resins.
It is used in an amount of 50 to 110 parts by weight per 00 parts by weight.

Similarly, in the present invention, when the blowing agents have the same particle size and are blended in the same amount into the same polyvinyl chloride paste resin, the blowing agents have the same cell diameter and the same amount under the same heating conditions. It refers to a blowing agent that forms a foamed structure having a cell number density, and usually the same blowing agent is used in the formulation for the upper layer and the formulation for the lower layer.

As the blowing agent, one that decomposes at a relatively high temperature is preferable, and for example, azocica-bonamide is preferable. As the blowing agent, commercially available products can be used, but a fine particulate blowing agent having a decomposition temperature of about 200'C1 and an average particle size of about 4 to 8 μm is preferable.

Furthermore, according to the present invention, as mentioned above, not only the degree of polymerization of the polyvinyl chloride paste resin in the polyvinyl chloride paste resin formulations for the upper layer and the lower layer is different; A method in which the upper layer has a larger melt viscosity when the mixture is heated and melted by blending a small amount of plasticizer with the formulation for the lower layer and a larger amount of plasticizer with the formulation for the lower layer. By blending a small amount of blowing agent into the mixture for the lower layer and a larger amount of foaming agent into the mixture for the lower layer, foam cells with a smaller diameter are formed in the upper layer when the foaming agent is foamed,
A method of forming foam cells with a larger diameter in the lower layer, (C
1. By blending a blowing agent with a larger particle size in the formulation for the upper layer and a blowing agent with a smaller particle size in the formulation for the lower layer, foam cells with a larger diameter can be created in the lower layer when the blowing agent is foamed. and (d) by incorporating a larger amount of the cell regulator into the formulation for the upper layer and a smaller amount of the cell regulator into the formulation for the lower layer, when the formulation is heated and melted, the upper layer becomes more concentrated. It is also possible to combine one or more of the above-described methods of obtaining a high melt viscosity with the method of selecting the degree of polymerization of the polyvinyl chloride paste resin.

However, as mentioned above, the plasticizer used in the above method (a) means a plasticizer that gives the same melt viscosity when added to the same polyvinyl chloride paste resin in the same amount; When employed, for example, the plasticizer in the formulation for the upper layer is preferably in the range of 50 to 90 parts by weight, particularly 60 to 80 parts by weight, based on 100 parts by weight of the polyvinyl chloride-based resin; The plasticizer in the formulation for the lower layer is 70 to 110 parts by weight based on 100 parts by weight of polyvinyl chloride-based resin;
In particular, it is preferably in the range of 80 to 100 parts by weight and greater than the amount of plasticizer in the formulation for the upper layer.

When employing the above method (b), the blowing agent is usually, but not limited to, 2 to 4 parts by weight per 100 parts by weight of the polyvinyl chloride base resin in the formulation for the upper layer. The formulation for the bottom layer contains 3 parts.
~6 parts by weight, and is blended in an amount larger than that in the formulation for the upper layer.

When using the above method (C1), the composition for the upper layer usually contains a blowing agent with an average particle size of about 10 to 20 μm.
In the formulation for the lower layer, a blowing agent having an average particle size of about 10 μm or less and smaller than the blowing agent in the formulation for the upper layer is used.

The blending amount and average particle size of the blowing agent are appropriately selected depending on the purpose of the present invention so as to provide an optimal combination.

In addition, the cell conditioner used in the above method (dl) means a cell conditioner that gives the same melt viscosity under the same heating conditions when blended with the same polyvinyl chloride paste 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-based 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, 8AP-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 paste 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 blowing agent when the compound is heated and melted, thereby facilitating the formation of an anisotropic foam structure. For example, since the Ba-Zn stabilizer accelerates the decomposition of the foaming agent, by adding it in a larger amount to 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 FL-54 (manufactured by Adeka Argus Chemical ■) whose main components are an aromatic carboxylic acid barium salt, an aliphatic carboxylic acid zinc salt, and a solvent.
can be preferably used.

In the present invention, a thickener may be added to the polyvinyl chloride paste resin formulation if necessary. 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 composition of the upper layer and lower layer thereon. It can be obtained by applying the mixture in the following order, immediately bonding it to a base fabric, heating and foaming the mixture, and peeling off the release paper after cooling. Note that the appropriate heating temperature for the compound is usually about 180 to 220°C.

In the synthetic leather according to the present invention obtained in this way, the upper layer is formed with cells having a diameter of substantially 100 to 300 μm at a cell number density of 600 to 2000 cells/cm2, and the lower layer is substantially formed with cells having a diameter of 200 to 300 μm. Cells having a diameter of ~800 μm and larger than the diameter of the upper layer are formed at a cell number density of 1000 to 3000 cells/crl. Preferably, in the upper layer, the cell diameter is substantially 1
00-200μm, cell number density 800-1500/
d, and in the lower layer, the cell diameter is substantially 200~
400. trm, cell number density 1000-3000 cells/d
It is.

As mentioned above, the synthetic leather according to the present invention has an anisotropic foamed layer consisting of an upper layer in which cells of small diameter are formed and a lower layer in which cells of large diameter are formed. Since it has a foamed 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.

To the formulation Parts Polyvinyl chloride paste resin (degree of polymerization 1650) 1
00 dioctyl phthalate 80B
a-Zn stabilizer FL54 (manufactured by Adeka Argus Chemical) 2-cell regulator BAP-
1 (Adeka Argus Chemical (sweeping)
1 Foaming agent uniform AZL (Daijin Chemical■
azocycarbonamide) 3 Thickener (
AC-1 manufactured by Shiraishi Kogyo) 4 Compound B Polyvinyl chloride paste resin (degree of polymerization 1300) 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 AZL (Azosicarbonamide manufactured by Daijin Kagaku 11) 3. Thickener (Shiraishi Kogyo Kokucho AC-1) 4. After drying with a reverse coater on release paper, so that the thickness becomes 10 μm,
Appropriately colored polyurethane resin (Dainichiseika ■, Rezamin 2825LP) was applied and dried by heating at 100°C for 2 minutes, then PVC sol (formulation A) was applied to a thickness of 200 μm using a knife coater and heated at 140°C. Heat for 2 minutes to make it semi-gel, and then add PVC sol (formulation B) on top of it.
was applied 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 200~
250, lJm, the cell number density was 1000 cells/Cta, the foam cell diameter of the lower layer was 350 to 400 μm, and the cell number density was 2000 cells/Cta. When this material was folded, it had fine wrinkles on its surface, was lightweight and flexible, and had an excellent texture.

Example 2 The following formulation C was used for the top layer and the following formulation C for the bottom layer. The number of parts indicates parts by weight.

Blend C Parts Polyvinyl chloride paste resin (degree of polymerization 1650) 100 Dioctyl phthalate 80Ba-
Zn-based stabilizer FL54 (manufactured by Adeka Argus Chemical) 2-cell regulator BAP-1 (
Manufactured by Adeka Argus Chemical)
1. Foaming agent uniform AZL (Azosicarbonamide manufactured by Daijin Kagaku Okiku) 3. Thickener (Shiraishi Kogyo type AC-1) 4. Compound vinyl chloride-vinyl acetate copolymer paste resin (degree of polymerization 1200) 100 Dioctyl phthalate 80 Ba-Zn stabilizer FL54 (manufactured by Adeka Argus Chemical) 2-cell regulator BAP
-1 (manufactured by Adeka Argus Chemical)
1 Foaming agent uniform AZL (Daijin Chemical ■
azocycarbonamide) 5 Thickener (
AC-1) (manufactured by Shiraishi Kogyo Co., Ltd.) 4 Semi-synthetic leather was obtained in the same manner as in Example 1 using these blends. This semi-synthetic leather has an upper layer foam cell diameter of 200~
250 μm, cell number density 1000 cells/Cml, lower layer foam cell diameter 500-700 pm, cell number density 28
00 pieces/d. When this material was folded, it had fine wrinkles on its surface, was lightweight and flexible, and had an excellent texture.

Example 3 For the top layer the same formulation A as in example 1 was used and for the bottom layer the following formulation E was used.

Blend E Parts Vinyl chloride-vinyl acetate copolymer paste resin (degree of polymerization 1200) 100 dioctyl phthalate 100 Ba-Zn stabilizer FL54 (manufactured by Adeka Argus Chemical ■)
2 cell conditioner BAP-1 (manufactured by Adeka Argus Chemical) 1
Foaming agent uniform AZL (Daijin Kagaku G-Kiku Azoshicarbonamide) 5 Thickener (Shiraishi Kogyo G-1) 3 Using these blends,
Semi-synthetic leather was obtained in the same manner as in Example 1. In this semi-synthetic leather, the foam cell diameter of the upper layer is 200 to 25
0μm, cell number density 1000 pieces/cut, lower layer foam cell diameter 500-700μm, cell number density 280
It was 0 pieces/d. 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
The mixture was heated for 2 minutes to form a semi-gel, and the base fabric was immediately attached. Next, heat and foam at 200°C for 1 minute and 30 seconds,
After cooling, the release paper was peeled off.

In the obtained semi-synthetic leather, the entire foam layer is homogeneous,
The foamed cell diameter was 200 to 250 μm and the cell number density was 1000 cells/d. 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 Blend B was used instead of Blend B in Comparative Example 1. This semi-synthetic leather is homogeneous as a whole, with a foam cell diameter of 350 to 400 μm and a cell number density of 2000 cells/ci.
Met. This was similar to natural leather and was flexible and lightweight, but no fine wrinkles were generated on the surface when it was folded.

Comparative Example 3 Semi-synthetic leather was obtained in exactly the same manner as in Comparative Example 1, except that Blend G was used instead of Blend A. This semi-synthetic leather is also homogeneous as a whole, with a foam cell diameter of 500 to 700 μm and a cell number density of 2800/C!
It was 11. This was similar to natural leather and was flexible and lightweight, but no fine wrinkles were generated on the surface when it was folded.

Patent applicant Band-Kagaku Co., Ltd. X ladder

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, 2 to 6 parts by weight of a blowing agent, and an appropriate amount of stabilizer, as a polyvinyl chloride paste resin in the formulation for the upper layer, Using a polyvinyl chloride paste resin with a higher degree of polymerization than the polyvinyl chloride paste resin in the formulation for the lower layer, the diameter of substantially
Cell number density of 300 μm is 600 to 2000/c
The upper layer is formed at m^2, and the diameter is substantially 200~
The cell number density is 1000 to 3000 cells/cm^ which is 800 μm and has a diameter larger than the diameter of the upper layer.
A method for producing synthetic leather having an anisotropic foam structure, which comprises forming a resin foam layer comprising a lower layer formed in step 2.