JPH04264144A - Production of porous polyurethane sheet - Google Patents

Abstract

PURPOSE:To produce a porous polyurethane sheet having a microporous structure, being flexible and excellent in moisture permeability and having a three- dimensional surface appearance. CONSTITUTION:A process for producing a porous polyurethane sheet by coating a releasable substrate with an organic solvent solution of a polyurethane resin, treating the coated substrate by the wet process and releasing the obtained sheet from the substrate, wherein the substrate comprises a woven fabric of polyester fibers and/or polyamide fibers and is pretreated with an aqueous dimethylformamide solution.

Description

Description: [0001] The present invention relates to a method for producing porous polyurethane sheets. More specifically, the present invention relates to a method for producing a porous polyurethane sheet that is free of macropores, has a microporous structure, is flexible, has excellent moisture permeability, and has a surface appearance with a three-dimensional effect due to the unevenness of a textile pattern. [0002] Conventionally, a solution of a polyurethane resin in an organic solvent is coated on a water-impermeable releasable substrate such as a polyester film, a polyamide film, or a glass plate, and after wet treatment, the releasability is improved. A method of manufacturing a porous polyurethane sheet by peeling it from a base material is known. [0003] However, in conventional manufacturing methods, the coagulation conditions for the side of the sheet that comes into contact with the releasable base material and the side that does not come into contact are significantly different. Therefore, the resulting porous polyurethane sheet was non-uniform and had insufficient flexibility and moisture permeability. Furthermore, the surface in contact with the releasable base material had a uniform surface appearance similar to a plastic surface. [Means for Solving the Problems] The present inventors have conducted intensive studies to obtain a porous polyurethane sheet that is free from such problems, is flexible, has excellent moisture permeability, and has a three-dimensional surface appearance. As a result, we have arrived at the present invention. That is, the present invention
In a method for manufacturing a porous polyurethane sheet by applying an organic solvent solution of a polyurethane resin to a releasable base material, wet-processing it, and then peeling it from the releasable base material,
This method of producing a porous polyurethane sheet is characterized in that the releasable base material is a woven fabric made of fibers selected from polyester fibers and/or polyamide fibers. In the present invention, the polyurethane resin includes organic diisocyanate (a) and a molecular weight of 500 to 5.
000 polymeric diol (b) and a low molecular weight chain extender (
Examples include polyurethane resins from c). Examples of the organic diisocyanate (a) include aromatic diisocyanates (4,4'-diphenylmethane diisocyanate, 2,4- and/or 2,6
-Tolylene diisocyanate, etc.), aliphatic diisocyanates (hexamethylene diisocyanate, lysine diisocyanate, etc.), alicyclic diisocyanates (isophorone diisocyanate, dicyclohexylmethane 4,4
'-diisocyanate, etc.), as well as these 2
Mixtures of more than one species are included. Examples of the polymer diol (b) having a molecular weight of 500 to 5,000 include polyether diol (a).
, polyester diol (b), polycarbonate diol (c), and mixtures thereof having the above-mentioned molecular weights. Examples of the polyether diol (a) include low-molecular diols (for example, ethylene glycol, propylene glycol, 1,4-butanediol, etc.) and alkylene oxides (alkylene oxides having 2 to 4 carbon atoms: ethylene oxide, propylene oxide, 1, 2-butylene oxide, etc.), cyclic ethers (tetrahydrofuran, etc.) or ring-opening copolymerization (block and/or
or randomly). (
Specific examples of b) include polyoxyethylene glycol, polyoxypropylene glycol, polyoxyethylene-polyoxypropylene (block or random)
glycol, polytetramethylene ether glycol,
Examples include polytetramethylene ether-polyoxyethylene (block or random) glycol, and mixtures of two or more thereof. As the polyester diol (b), condensed polyester diol obtained by reacting a low molecular weight diol and/or a polyether diol with a molecular weight of 1000 or less with dicarboxylic acid, and polycaprolactone diol obtained by ring-opening polymerization of lactone. Examples include. Examples of the low-molecular diol include the same low-molecular diols exemplified in section (a). Molecular weight 10
Among the polyether diols exemplified in section (a), polyether diols with a molecular weight of 100 or less are
Examples include 0 or less. Examples of dicarboxylic acids include aliphatic dicarboxylic acids (eg, succinic acid, adipic acid, sebacic acid, etc.), aromatic dicarboxylic acids (terephthalic acid, isophthalic acid, etc.), and mixtures of two or more of these. Examples of the lactone include ε-caprolactone. Specific examples of (b) include polyethylene adipate, polybutylene adipate, polyethylene butylene adipate, poly(tetramethylene ether) adipate, polycaprolactone diol, and mixtures of two or more of these. Examples of the polycarbonate diol (c) include polybutylene carbonate diol and polyhexamethylene carbonate diol. Examples of the low molecular weight chain extender (c) include the low molecular weight diols exemplified in section (a), aliphatic diamines (ethylene diamine etc.), alicyclic diamines (isophorone diamine etc.), aromatic diamines (4 , 4'-diaminodiphenylmethane, etc.), aromatic aliphatic diamines (xylene diamine, etc.), alkanolamines (ethanolamine, etc.), hydrazine, and mixtures of two or more of these. Polyurethane resins can be produced by conventional methods, such as the one-shot method in which (a), (b) and (c) are reacted simultaneously, or the NCO method in which (a) and (b) are reacted. Examples include a prepolymer method in which a terminal prepolymer is produced and then reacted with (c). The production of polyurethane resins can be carried out in the presence or absence of solvents. Such solvents include amide solvents (dimethylformamide, dimethylacetamide, etc.), sulfoxide solvents (dimethylsulfoxide, etc.), and ketone solvents (methyl ethyl ketone, etc.).
, ether solvents (dioxane, tetrahydrofuran, etc.), and mixtures of two or more of these. Preferred are amide solvents and sulfoxide solvents. The solvents exemplified above can also be used as organic solvent components of the organic solvent solution of the polyurethane resin. [0014] In the production of polyurethane resin, the reaction temperature may be the same as that normally employed in polyurethanization reactions, and is usually 20 to 100°C when a solvent is used, and usually 20 to 220°C when no solvent is used. . In order to accelerate the reaction, catalysts commonly used in polyurethane reactions, such as amine catalysts (triethylamine, triethylenediamine, etc.), tin catalysts (dibutyltin dilaurate, etc.), may be used if necessary. [0016] If necessary, a polymerization terminator [for example, 1
Hydrolic alcohols (ethanol, butanol, etc.), monovalent amines (methylamine, butylamine, etc.)] can also be used. [0017] The polyurethane resin can be produced using production equipment normally employed in the industry. Moreover, when a solvent is not used, a manufacturing device such as a kneader or an extruder can be used. It is practically preferable that the polyurethane resin thus produced has a solution viscosity of 20 to 10,000 poise/20° C. when measured as a 30% by weight (solid content) DMF solution. The organic solvent solution of the polyurethane resin may be the polyurethane resin solution produced in the presence of the solvents exemplified above, or, if the polyurethane resin is produced in the absence of a solvent, the organic solvent solution further exemplified above may be used. It may be dissolved in a solvent to form a polyurethane solution. The concentration of the solution is usually 5 to 40% by weight, preferably 10 to 30% by weight. The polyurethane resin solution contains resins other than polyurethane resins, such as polyvinyl chloride, polyacrylic acid ester, polymethacrylic acid ester, polystyrene, polyacrylonitrile, acrylonitrile-vinylidene chloride copolymer, and vinyl chloride-vinyl acetate copolymer. Combinations can also be combined. [0022] If necessary, an antioxidant [4,4'-
Hindered phenols such as butylidene-bis(3-methyl-6-t-butylphenol); organic phosphites such as triphenyl phosphite and trichloroethyl phosphite], ultraviolet absorbers (benzophenone type, benzotriazole type, etc.), Light stabilizers (hindered amine type, etc.), stabilizers (carboxylic acid, phosphoric acid, oxycarboxylic acid, etc.), pigments (titanium oxide, carbon black, etc.), fillers (calcium carbonate, diatomaceous earth, etc.), organic modifiers (cellulose powder) etc.), plasticizers, antistatic agents, bactericidal agents, and known coagulation regulators [higher alcohols (Japanese Patent Publication No. 42-22719), hydrophobic nonionic surfactants (Japanese Patent Publication No. 45-39634 and Japanese Patent Publication No. 45-1989), 39
635), polyoxyalkylene-modified dimethylpolysiloxane (Japanese Patent Publication No. 58-39451), etc.]
can be added. Anionic, nonionic, cationic or amphoteric surfactants can also be used as solvent removal promoters. [0024] In the present invention, the resin for producing polyester fibers and polyamide fibers may be any resin that is mainly composed of polyester or polyamide that can be molded into fibers. Examples of this polyester include polyesters synthesized from terephthalic acid, isophthalic acid, adipic acid, sebacic acid, or their esters and diol compounds such as ethylene glycol, diethylene glycol, neopentyl glycol, and cyclohexane-1,4-dimethanol. Can be mentioned. Among these, preferred are polyethylene terephthalate, or copolymerized polyethylene terephthalate in which at least 90% of its repeating units are polyethylene terephthalate (copolymerized components include polyalkylene glycol, glycerin, pentaerythritol, methoxypolyalkylene glycol, In addition to bisphenol A, p-oxybenzoic acid, etc., the above-mentioned carboxylic acids, glycols, etc.). Examples of the polyamides include nylon 6,6 synthesized from hexamethylene diamine and adipic acid, nylon 6 synthesized from ε-caprolactam, and nylon 6,10 synthesized from hexamethylene diamine and sebacic acid. Can be mentioned. [0026] The above polyester and polyamide may also contain additives such as coloring pigments, flame retardants, fragrances, and matting agents. [0027] The polyester fibers and/or polyester fibers obtained by spinning the polyesters and polyamides exemplified above, respectively.
The thickness of the fiber selected from polyamide fibers is usually 10 to 200 deniers, preferably 30 to 150 deniers.
It is denier. If it is less than 10 denier, the unevenness will be shallow.
If the denier exceeds 200 denier, the surface appearance becomes rough and lacks a three-dimensional effect. [0028] In the present invention, the woven fabric includes plain weave, diagonal weave, and satin weave of polyester fibers or polyamide fibers. Plain weave is preferred. In addition, the density of the fabric is usually 30 to 300 warps/
inch, and 30 to 300 wefts/inch. Preferably 50-250 warps/inch, 50-250 wefts/inch
book/inch. If the warp and weft density is less than 30 yarns/inch, the surface appearance will be rough, and if it exceeds 300 yarns/inch, the surface appearance will be shallow and lack three-dimensionality. The fabric may also be dyed with a disperse dye or acid dye, heat treated with a calendar roll, or treated with a silicone or fluorine water repellent. The woven fabric may also be treated with a resin such as urea resin, melamine resin, acrylic resin, vinyl chloride resin, etc. within a range that does not impair the effects of the present invention. In this case, the resin adhesion amount is usually 10g/m2
It is preferably 5 g/m2 or less. [0031] The releasable base material made of the woven fabric is preferably pretreated with an aqueous dimethylformamide solution. In the case of an aqueous dimethylformamide solution, the concentration of dimethylformamide in this aqueous solution is usually 5 to 90% by weight, preferably 40 to 80% by weight. To illustrate this pretreatment method, the fabric is immersed in a bath of an aqueous dimethylformamide solution,
One method is to squeeze it with nip rolls. The squeezing rate when squeezing with this nip roll is the pickup rate, which is usually 5.
-200%, preferably 10-100%. If the reduction rate is less than 5%, it will be difficult to peel it off from the base material after wet processing. If it exceeds 200%, peeling may occur during wet processing, which is not preferable. [0032] The polyurethane resin solution may be applied to the releasable base material made of the fabric by any conventional method. Examples include coating methods such as knife coating, roll coating, and roll-over knife coating. [0033] The amount of polyurethane resin solution applied to the base material is usually 10 to 3,000 μm, preferably 30 to 2,000 μm.
It is 0μ. In the present invention, a non-solvent for polyurethane resin is used as the liquid used in the wet treatment, a coagulation bath for coagulating the polyurethane resin solution, such as water, methanol, ethylene glycol, and mixtures thereof. It will be done. Also, a mixture of the above liquid and the above-mentioned organic solvent (mixing ratio: normal weight ratio: 95:
5-30:70) can also be used. Preferred among these are water and mixtures of water and solvents. [0035] Examples of the wet processing method include conventional methods, such as a method in which a substrate coated with a polyurethane resin solution is immersed in a coagulation bath, a method in which the substrate is partially coagulated with water vapor, and then immersed in a coagulation bath. After the wet treatment, solvent removal and washing (
A porous polyurethane sheet is obtained by drying the polyurethane sheet (with water, methanol, etc.), and then peeling it off from the substrate. The obtained sheet may be used as is. It may also be used by bonding it to other base materials (non-woven fabric, knitted fabric, woven fabric, etc.) using an adhesive. Alternatively, the front or back surface may be ground with sandpaper or the like. [Examples] The present invention will be further explained below with reference to Examples, but the present invention is not limited thereto. In Examples and Comparative Examples, parts represent parts by weight, and % represents weight %. Polyurethane resin solution production example 1 200 g of polybutylene adipate with an average molecular weight of 2000, 1,4
-24.7 g of butanediol and 93.8 g of 4,4'-diphenylmethane diisocyanate were added to 743 g of dimethylformamide and reacted in a dry nitrogen atmosphere to obtain a polyurethane resin solution (A ) was obtained. Using this solution, solutions as shown in Table 1 were prepared. [Table 1] Example 1 Polyester fabric (plain weave, yarn count and density: warp 7
90 threads/inch for 5d weft and 100 threads/inch for 75d weft) were immersed in a 50% dimethylformamide aqueous solution and squeezed with nip rolls.The squeezing rate at this time was 40% in terms of pick-up rate. Next, apply the adjustment liquid in Table 1 to a thickness of 0.
．． 7mm coated, room temperature water/DMF ratio: 70/
The sample was washed by immersing it in a coagulation bath of No. 30 for 5 minutes, then in a warm water bath of 50 to 60°C for 20 minutes, and then in room temperature water for 10 minutes. Next, it was dried at 70 to 110°C and then peeled off from the polyester fabric to obtain a porous sheet. Table 3 shows the shape and properties of the obtained porous sheet. Comparative Example 1 The adjustment solution in Table 1 was applied to a polyester film [Lumirror #20].
Polyester film manufactured by Toray Industries, Inc.] was coated, wet treated, washed, dried, and then peeled off in the same manner as in Example 1 to obtain a porous sheet. Table 3 shows the shape and properties of the obtained porous sheet. Polyurethane resin solution production example 2 200 g of polyethylene butylene adipate with an average molecular weight of 2000
, 16.1 g of ethylene glycol and 90.1 g of 4,4'-diphenylmethane diisocyanate were added to 715 g of dimethylformamide and reacted in a dry nitrogen atmosphere to obtain a polyurethane resin solution (B) with a resin concentration of 30% and a viscosity of 1500 poise (20°C). I got it. Using this solution, solutions as shown in Table 2 were prepared. [Table 2] Example 2 Polyester fabric (plain weave, yarn count and density: warp 6
100 pieces/inch for 0d, 110 pieces/inch for 60d weft
inch) was immersed in a 30% dimethylformamide aqueous solution and squeezed with nip rolls.The squeezing rate at this time was 30% in terms of pick-up rate. Next, apply the adjustment liquid in Table 2 to a thickness of 1.0 mm, and the water/DMF ratio at room temperature is 9.
0/10 coagulation bath for 8 minutes, then 50-60℃
20 minutes in a hot water bath, then 1 hour in a 60-70℃ hot water bath.
It was soaked for 0 minutes and then washed. Next, it was dried at 70 to 110°C and then peeled off from the polyester fabric to obtain a porous sheet. Table 3 shows the shape and properties of the obtained porous sheet. Comparative Example 2 The adjustment solution in Table 2 was applied to a polyester film [Lumirror #25].
Polyester film manufactured by Toray Industries, Inc.] was coated, wet treated, washed, dried, and then peeled off in the same manner as in Example 2 to obtain a porous sheet. Table 3 shows the shape and properties of the obtained porous sheet. [Table 3] As is clear from Table 3, the porous sheets of Examples 1 and 2 had fine pores in cross section, and the porous sheets had excellent texture and moisture permeability. Furthermore, the surface had the three-dimensional effect of a textile pattern. Effects of the Invention: The porous polyurethane sheet obtained by the production method of the present invention has a fine pore structure without macropores, is flexible, has excellent moisture permeability, and has a three-dimensional surface appearance. This is a sheet with Because of the above effects, the porous polyurethane sheet of the present invention is useful for clothing, medical use, furniture, decoration, construction, industrial materials, and the like.

Claims (3)

[Claims] Claim 1. A method for manufacturing a porous polyurethane sheet by applying an organic solvent solution of a polyurethane resin to a releasable base material, subjecting it to wet treatment, and then peeling it from the releasable base material. 1. A method for producing a porous polyurethane sheet, characterized in that a woven fabric made of fibers selected from polyester fibers and/or polyamide fibers is used as a flexible base material. [Claim 2] The thickness of the fiber is 10 denier to 20 denier.
2. The manufacturing method according to claim 1, wherein the fabric has a warp yarn density of 30 to 300 yarns/inch. 3. The manufacturing method according to claim 1, wherein the releasable substrate is pretreated with an aqueous dimethylformamide solution having a concentration of 5 to 90%.