JPH09272753A - Production of microporous sheet, and microporous sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a microporous sheet excellent in mechanical properties at a high productivity without using an org. solvent by dispersing a specific powder in a water-base binder liq. in a specified ratio, forming a layer from the resultant dispersion on a substrate, and drying the layer. SOLUTION: A powder of a water-insol. org. polymer pref. selected from among polyurethane, polyamide, acrylic, and polyvinyl acetate resins (e.g. a nylon resin) is dispersed in a water-base binder liq., pref. a water-base liq. of a polyurethane resin, in a wt. ratio (solid basis) of 100:(3-300). pref. 100:(100100). A layer is formed from the resultant dispersion on a substrate (e.g. a nonwoven polyester fabric), dried, and if necessary peeled from the substrate. A water-base liq. of a polyurea, acrylic, styrene-acrylic. polyester, polyamide, ethylene-vinyl acetate, or PVC resin is also pref. as the binder liq.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a microporous sheet and a microporous sheet for artificial leather, synthetic leather or resin coated fiber products. More specifically, a method for producing a highly porous microporous sheet having excellent properties such as mechanical properties and moisture permeability, which can be used as artificial leather, synthetic leather, resin coated fiber products, etc., and an artificial method obtained by this method. The present invention relates to a microporous sheet for leather, synthetic leather or resin coated fiber products.

[0002]

2. Description of the Related Art Conventionally, as a method for producing a microporous sheet, a method of applying an organic polymer such as polyurethane as a solution of a water-soluble organic solvent to a fiber material and wet coagulating it, or a dry method (for example, Japanese Patent Publication No. No. 41063 and JP-A No. 51-41063), W of polyurethane resin containing fine polyurethane particles
A method using an / O type emulsion (for example, the method described in JP-A-62-273220) is known.

[0003]

However, in the above wet method, since the organic solvent used is highly flammable and highly toxic, there are problems such as fire risk and high solvent recovery cost; In the method, since a large amount of hydrophilic resin is used, the mechanical properties of the obtained sheet material cannot be said to be sufficient, and the manufacturing method thereof is complicated, and the drying method requires strict temperature control, In the method using a W / O type emulsion of a polyurethane resin containing polyurethane fine particles, the productivity is very low because it takes time; There was a problem.

[0004]

Means for Solving the Problems As a result of intensive investigations by the present inventors on a method for solving the above-mentioned problems, a method for producing a microporous sheet which does not require the use of an organic solvent and which can be produced with high productivity has been found. Found and arrived at the present invention. That is, in the present invention, the water-insoluble organic polymer powder (A) is added to the binder aqueous liquid (B) in a solid content weight ratio (A) :( B).
= 100: a method for producing a microporous sheet, which comprises forming a layer comprising a dispersion of (3 to 300) on a substrate, drying the layer, and peeling the layer from the substrate if necessary; and The water-insoluble organic polymer powder (A) is added to the binder aqueous liquid (B) in a solid content weight ratio (A) :( B).
= 100: a fine layer for artificial leather, synthetic leather, or resin-coated fiber product, which is formed by forming a layer comprising a dispersion of (3 to 300) on a substrate, drying it, and peeling it off from the substrate if necessary. It is a porous sheet.

The powder (A) in the present invention is not particularly limited as long as it is a powder of a water-insoluble organic polymer. Examples of the water-insoluble organic polymer include polyethylene-based, polypropylene-based, polybutadiene-based, polystyrene-based,
Examples thereof include polyurethane-based, polyamide-based, acrylic-based, polyester-based, polyvinyl acetate-based, ethylene / vinyl acetate-based copolymer, polyvinyl chloride-based, and epoxy resin-based resins. Among these, preferred are polyurethane-based, polyamide-based, acrylic-based, and polyvinyl acetate-based, because they have good adhesiveness with a binder and can provide a sheet with good durability, and the resulting sheet has a soft texture. And polyvinyl chloride resins. The average particle size of the powder (A) is usually 0.01 to 5000 μm, preferably 0.1 to 100 μm. Average particle size 0.0
If it is less than 1 μm, the voids formed in the obtained sheet become small, and a microporous sheet having good moisture permeability cannot be formed.
When it exceeds 00 μm, the mechanical strength of the obtained microporous sheet is lowered.

Examples of the binder aqueous liquid (B) include polyurethane resins, polyurea resins, acrylic resins (polyacrylic acid ester, etc.), polystyrene resins, styrene-acrylic resins, polyester resins,
Aqueous liquids of resins such as polyamide resins, polyimide resins, polyamino acid resins, partially saponified polyvinyl acetate, ethylene / vinyl acetate resins, polyvinyl chloride resins, epoxy resins, SBR, NBR, EPR, Examples thereof include aqueous liquids of rubber such as polybutadiene rubber, butyl rubber, and natural rubber. These aqueous liquids may be an aqueous dispersion or an aqueous solution, and may be anionic, cationic or nonionic. Among these, preferred ones are polyurethane resin, polyacrylic ester, because the texture of the obtained sheet is flexible,
Aqueous solutions or dispersions of polyamide resins or partially saponified polyvinyl acetate, SBR latex and natural rubber latex, and particularly preferred are aqueous dispersions of polyurethane.

The solid content weight ratio of (A) and (B) is usually 1
00: (3 to 300), preferably 100: (10 to 1)
00). If the ratio of (B) is less than 3, the binder effect due to (B) will be poor and the mechanical strength of the resulting sheet will be reduced, and if it exceeds 300, the voids of the obtained sheet will be small and the moisture permeability will be reduced. To do.

In the present invention, when a layer comprising the powder (A) dispersed in the aqueous liquid (B) is formed on a substrate, a water-soluble solvent such as methanol or ethanol may be added, if necessary. , Surfactants such as alkylene oxide adducts of alkylphenols, thickeners such as carboxymethyl cellulose, defoaming agents such as silicon compounds, leveling agents such as fluorine compounds, crosslinking agents such as polyepoxy compounds and amino resins, pigments , A migration inhibitor and the like are blended. Further, as a method for obtaining a dispersion of the powder (A) in the aqueous liquid (B), an aqueous liquid (B) of a resin in which the core material of the microporous sheet (A) is a binder is used.
There is no particular limitation as long as it is a method of dispersing the powder (A) in it, for example, a method of directly dispersing the dried powder (A) in (B), and a method of dispersing the dried powder (A) in an alkylphenol alkylene, if necessary. A method of previously dispersing in water with a surfactant such as an oxide adduct and then dispersing in (B), or mixing (A) synthesized in the state of being dispersed in water with (B) without drying. However, a method of dispersing and the like can be mentioned.

As a substrate for obtaining the microporous sheet, for example, knitted cloth, woven cloth or non-woven cloth of natural fiber, semi-synthetic fiber, synthetic fiber, etc., paper, plastic film,
A metal plate, a glass plate, a release paper, etc. are used.

As a method of adhering to the substrate, (A)
Examples of the method include a method in which a base material is treated with a method of impregnating a base material with an aqueous liquid in which (B) is dispersed, coating, spraying, and the like, and then an excessive amount is squeezed if necessary, followed by heating and drying. The drying conditions are usually 10 seconds to 10 minutes at 60 to 180 ° C., though varying depending on the substrate, the composition of the aqueous liquid in which (A) is dispersed in (B), the amount of adhesion, and the like. When the drying temperature is equal to or higher than the thermal softening point of (A), fusion of the powder occurs, and the flexibility and moisture permeability of the resulting microporous sheet are reduced. To do. After drying, the microporous sheet is obtained by peeling it off from the substrate if necessary. Examples of the substrate for peeling from the substrate include a plastic film, a metal plate, a glass plate and a release paper. The amount of the compounded liquid adhered to the base material is arbitrarily selected depending on the purpose, but is usually 5 to 3000 g per 1 m ^{2 of} the base material.

In the production method of the present invention, a layer comprising (A) dispersed in (B) is formed on a substrate, and then (A) having a different average particle size is added onto (B). It is also possible to form a layer composed of the material dispersed in the above to form a sheet having a multilayer structure. For example, the average particle size is 5-5
The powder (A1) of water-insoluble organic polymer of 00μ is added to (B)
After forming a layer of the water-insoluble organic polymer having a mean particle size of ⅕ or less of (A1) on the substrate, a layer (A2) ), A microporous sheet obtained by forming a layer consisting of a material dispersed in) has the rebound resilience unique to natural leather, and exhibits highly similar physical properties to natural leather, such as wrinkles being formed when folded. To do. As (B) used to disperse each of (A1) and (A2), the same or different one may be used.

[0012]

The present invention will be further described with reference to the following examples.
The present invention is not limited to this. Parts in Examples are parts by weight, and% means% by weight. In addition, the measuring method of each measured value used in an Example is as follows. Water vapor transmission rate: JIS Z 0208B (g / m ² · 24h) Flexibility: Tactile sensation by handling

Example 1 Nylon resin powder (average particle size 50 μ, thermal softening point 150
100 parts of polyurethane resin emulsion, 100 parts of polyurethane resin emulsion ["Permarin UA-150" manufactured by Sanyo Chemical Industry Co., Ltd., solid content concentration: 30%) and 240 parts of water are mixed and dispersed, and 3 parts of carboxymethyl cellulose is added thereto. hand,
An aqueous dispersion having a solid content concentration of 30% and a viscosity of 5000 cP was obtained. This was coated on a polyester (PET) ultrafine fiber nonwoven fabric so as to have a thickness of 1 mm, and dried at 100 ° C. for 10 minutes to obtain a microporous sheet.

Example 2 100 parts of polyurethane resin powder (average particle size 100 μ, thermal softening point 140 ° C.), polyurethane resin emulsion [“Permarin UA-150” manufactured by Sanyo Kasei Co., Ltd.,
Solid content concentration 30%)] and 240 parts of water were mixed and dispersed, and 3 parts of carboxymethyl cellulose was added thereto to obtain an aqueous dispersion having a solid content concentration of 30% and a viscosity of 5000 cP. 1m thick on PET ultrafine fiber
m to obtain a microporous sheet by coating and drying at 100 ° C. for 10 minutes.

Example 3 A PET ultrafine fiber non-woven fabric was coated with the aqueous dispersion obtained in Example 2 so as to have a thickness of 0.6 mm.
After drying for 10 minutes at ℃, further 10 powder of acrylic resin (average particle size: 1μ, thermal softening point: 170 ℃) 10
0 parts, SBR latex [JS manufactured by Japan Synthetic Rubber Co., Ltd.
R-0548 ", solid content concentration 50%) 40 parts and water 2
10 parts were mixed and dispersed, and 2 parts of carboxymethyl cellulose was added thereto to obtain a solid content concentration of 35% and a viscosity of 7000c.
The aqueous dispersion P was coated to a thickness of 0.4 mm and dried at 100 ° C. for 10 minutes to obtain a microporous sheet having a two-layer structure.

Example 4 The aqueous dispersion obtained in Example 1 was coated on a release paper with a thickness of 0.5 m.
m to obtain a microporous sheet by coating and drying at 100 ° C. for 10 minutes. The moisture permeability was measured by peeling off the release paper.

Comparative Example 1 Polyurethane resin powder (average particle size 100 μ, thermal softening point 140 ° C.) 10 parts, polyurethane resin emulsion [Sanyo Kasei Co., Ltd. "Permarin UA-150", solid content concentration: 30% ) 300 parts and 28 parts of water are mixed and dispersed, to which 2 parts of carboxymethyl cellulose is added,
An aqueous dispersion having a solid content concentration of 30% and a viscosity of 5000 cP was obtained. This was coated on a PET ultrafine fiber nonwoven fabric so as to have a thickness of 1 mm, and dried at 100 ° C. for 10 minutes to obtain a comparative sheet.

Comparative Example 2 Nylon resin powder (average particle size 50 μ, thermal softening point 150
C) 100 parts, polyurethane resin emulsion [Sanyo Kasei Co., Ltd. "Permarin UA-150", solid content concentration: 30%) 5 parts and water 240 parts are mixed and dispersed, and 3 parts of carboxymethyl cellulose is added thereto. An aqueous dispersion having a solid content concentration of 30% and a viscosity of 6000 cP was obtained. This was coated on a PET ultrafine fiber nonwoven fabric so as to have a thickness of 1 mm and dried at 100 ° C. for 10 minutes, but the powder was scattered and did not adhere, and a sheet-like material was not obtained.

Performance Test Table 1 shows the performance evaluation results of the sheet-like materials obtained in Examples 1 to 4 and Comparative Example 1.

[0020]

[Table 1] Note) Explanation of symbols ○: Good, ×: Poor

[0021]

The method for producing a microporous sheet of the present invention comprises:
It has the following effects that cannot be achieved by the conventional technology. (1) Since it does not contain an organic solvent, there is no danger of ignition or toxicity, and no solvent recovery equipment is required, which is advantageous in terms of cost. (2) Since no hydrophilic resin is used, a sheet having good mechanical properties can be obtained. (3) The manufacturing method is simple, and strict temperature control is not required for drying, and moreover, it can be dried in a short time, so that high productivity can be secured. (4) Since the resin powder and the binder resin to be constituted can be selected in a wide range, a microporous sheet having a wide range of physical properties can be manufactured. The microporous sheet obtained by using the method of the present invention can be widely used as artificial leather, synthetic leather, resin-coated fiber products and the like.

Claims (5)

[Claims] 1. A water-insoluble organic polymer powder (A) is added to a binder aqueous liquid (B) in a solid content weight ratio (A) :( B).
= 100: A method for producing a microporous sheet, which comprises forming a layer composed of a dispersion of (3 to 300) on a substrate, drying the layer, and peeling the layer from the substrate if necessary. 2. A layer comprising a powder (A1) of a water-insoluble organic polymer having an average particle size of 5 to 500 μ dispersed in (B) is formed on a substrate, and then the layer is averaged. The production method according to claim 1, wherein a layer formed by dispersing a water-insoluble organic polymer powder (A2) having a particle diameter of ⅕ or less of the powder (A1) in (B) is formed. . 3. The water-insoluble organic polymer powder (A) is any organic polymer powder selected from the group consisting of polyurethane resins, polyamide resins, acrylic resins and polyvinyl acetate resins. The manufacturing method according to claim 1 or 2. 4. A binder aqueous liquid (B) is a polyurethane resin, polyurea resin, acrylic resin, styrene-acrylic resin, polyester resin, polyamide resin, partially saponified polyvinyl acetate, ethylene / vinyl acetate. The method according to any one of claims 1 to 3, which is an aqueous liquid of a resin selected from the group consisting of a system resin, a polyvinyl chloride resin, SBR, and natural rubber. 5. A water-insoluble organic polymer powder (A) is added to a binder aqueous liquid (B) in a solid content weight ratio (A):
(B) = 100: artificial leather, synthetic leather, or resin-coated fiber, which is formed by forming a layer composed of a dispersion of (3 to 300) on a base material, drying it, and peeling it off from the base material if necessary. Microporous sheet for products.