TWI874372B - Method for manufacturing porous body - Google Patents

Abstract

The present invention provides a method for manufacturing a porous body, which is a method for manufacturing a porous body by wet-forming a urethane resin composition containing a urethane resin (A), a solvent (B), and a film-forming aid (C), wherein the film-forming aid (C) is a polysilicone compound (c1) having an oxyethylene structure. The polysilicone compound (c1) is preferably one that further has a hydroxyl group. The number average molecular weight of the polysilicone compound (c1) is preferably in the range of 500 to 5,000. The content of the polysilicone compound (c1) is preferably in the range of 0.1 to 30 parts by mass relative to 100 parts by mass of the urethane resin (A). According to the present invention, by using a specific film-forming aid and utilizing a wet film-forming method, a porous body having fine and uniform cells, a sense of weight, and a soft texture can be manufactured.

Description

Method for manufacturing porous body

The present invention relates to a method for manufacturing a porous body using a wet membrane forming method.

In the field of artificial leather and synthetic leather, sheets made by processing urethane resin compositions containing organic solvents are widely used. There are two methods for processing the urethane resin compositions, dry method and wet method, but among these, the wet method (wet film forming method) that forms a porous body can give good texture and flexibility, so the leather obtained has a place in high-end products (for example, refer to patent document 1).

On the other hand, in order to demonstrate such performance, fine control of cell shape is indispensable, but such control is difficult, and people are eager to establish a method to make it easier. [Prior art literature] [Patent literature]

Patent document 1: Japanese Patent Application Publication No. 4-300370

[Problems to be solved by the invention]

The problem to be solved by the present invention is to provide a method for producing a porous body having fine and uniform cells, a sense of weight, and a soft texture by using a wet film forming method. [Means for solving the problem]

The present invention provides a method for manufacturing a porous body, which is a method for manufacturing a porous body by wet-forming a urethane resin composition containing a urethane resin (A), a solvent (B), and a film-forming aid (C), wherein the film-forming aid (C) is a polysiloxane compound (c1) having an oxyethylene structure. [Effect of the invention]

According to the present invention, by using a specific film-forming aid and utilizing a wet film-forming method, a porous body having fine and uniform cells, a sense of weight, and a soft texture can be manufactured. Therefore, the present invention can be particularly suitably used in the manufacture of polishing pads, artificial leather, and synthetic leather.

Furthermore, in the present invention, the aforementioned "porous body" refers to a body having a large number of pores that are naturally obtained when the urethane resin composition is solidified by a wet film forming method, for example, a body having a long-spun hammer-shaped or teardrop-shaped porous structure formed in the thickness direction of the surface.

[Form used to implement the invention]

The present invention is a method for producing a porous body by wet-forming a urethane resin composition containing a urethane resin (A), a solvent (B), and a specific film-forming aid (C).

In the present invention, a polysilicone compound (c1) having an oxyethylene structure must be used as a film-forming aid (C). The polysilicone compound (c1) has high hydrophilicity and easily absorbs water when the urethane resin solidifies, thereby obtaining a porous body with easy control of cells and good texture.

The polysilicone compound (c1) is an oily polysilicone compound having a main chain composed of siloxane bonds and an oxyethylene structure at the end or side chain of the main chain.

From the viewpoint of further improving hydrophilicity and obtaining better cell formation and texture, the polysilicone compound (c1) preferably has a reactive group. Examples of the reactive group include a hydroxyl group and an epoxy group. Among these, a hydroxyl group is preferred from the viewpoint of obtaining better cell formation and texture.

From the viewpoint of obtaining better cell formation and texture, the number average molecular weight of the polysilicone compound (c1) is preferably in the range of 500 to 5,000, more preferably in the range of 1,000 to 4,000. The number average molecular weight of the polysilicone compound (c1) is a value measured by gel permeation chromatography (GPC) under the following conditions.

As the aforementioned polysilicone compound (c1), for example, the following commercially available products can be obtained: "KF355A", "KF644", "KF6204", "X-22-4592", "X-22-4272", "KF6123", "X-22-4741", "KF1002" (all manufactured by Shin-Etsu Chemical Co., Ltd.), "BY16-201", "SF-8427", "SF-8428", "FZ-2162", "SH3773M" (all manufactured by Dow Corning Toray Co., Ltd.), etc.

From the viewpoint of obtaining better cell formation and texture, the content of the polysilicone compound (c1) is preferably in the range of 0.1 to 30 parts by mass, more preferably in the range of 0.5 to 20 parts by mass, based on 100 parts by mass of the urethane resin (A).

As the urethane resin (A) used in the present invention, for example, a reaction product of a polyol (a1) and a polyisocyanate (a2) can be used.

As the polyol (a1), for example, polyester polyol, polyether polyol, polycarbonate polyol, etc. These polyols may be used alone or in combination of two or more.

From the viewpoint of mechanical properties and flexibility of the porous body, the number average molecular weight of the polyol (a1) is preferably in the range of 500 to 10,000, more preferably in the range of 700 to 8,000. The number average molecular weight of the polyol (a1) is a value measured by gel permeation chromatography (GPC).

The polyol (a1) may be used in combination with a chain extender (a1-1) having a number average molecular weight of less than 500, if necessary. Examples of the chain extender (a1-1) include a chain extender having a hydroxyl group and a chain extender having an amino group. The chain extenders (a1-1) may be used alone or in combination of two or more.

As the chain extender having a hydroxyl group, for example, aliphatic polyol compounds such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, hexamethylene glycol, sucrose, methylene glycol, glycerol, and sorbitol; aromatic polyol compounds such as bisphenol A, 4,4'-dihydroxybiphenyl, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl sulfone, hydrogenated bisphenol A, and hydroquinone; and water can be used. Such chain extenders can be used alone or in combination of two or more.

As the aforementioned chain extender having an amino group, for example, ethylenediamine, 1,2-propylenediamine, 1,6-hexamethylenediamine, piperidine , 2-methylpiperidin , 2,5-dimethylpiperidin , isophorone diamine, 4,4'-dicyclohexylmethanediamine, 3,3'-dimethyl-4,4'-dicyclohexylmethanediamine, 1,2-cyclohexanediamine, 1,4-cyclohexanediamine, aminoethylethanolamine, hydrazine, diethylenetriamine, triethylenetetramine, etc. These chain extenders may be used alone or in combination of two or more.

As the polyisocyanate (a2), for example, aromatic polyisocyanates such as 4,4′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, carbodiimide-modified diphenylmethane diisocyanate, crude diphenylmethane diisocyanate, phenylene diisocyanate, toluene diisocyanate, naphthalene diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, etc.; aliphatic polyisocyanates such as hexamethylene diisocyanate and lysamine diisocyanate; alicyclic polyisocyanates such as cyclohexane diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, etc. can be used. These polyisocyanates may be used alone or in combination of two or more.

As a method for producing the urethane resin (A), for example, there can be cited a method of producing by adding the polyol (a1) and the polyisocyanate (a2), and optionally adding the chain extender (a1-1), and reacting them. Such reaction is preferably carried out at a temperature of 50 to 100° C. for about 3 to 10 hours. In addition, the above reaction can also be carried out in the solvent (B) described below.

The molar ratio of the total of the hydroxyl group of the polyol (a1) and the hydroxyl group and the amino group of the chain extender (a1-1) to the isocyanate group of the polyisocyanate (a2) [(isocyanate group)/(hydroxyl group and amino group)] is preferably in the range of 0.8 to 1.2, more preferably in the range of 0.9 to 1.1.

From the viewpoint of mechanical strength and flexibility of the porous body, the weight average molecular weight of the urethane resin (A) obtained by the above method is preferably in the range of 5,000 to 1,000,000, more preferably in the range of 10,000 to 500,000. The weight average molecular weight of the urethane resin (A) is a value measured in the same manner as the number average molecular weight of the polyol (a1).

The content of the urethane resin (A) may be, for example, in the range of 10 to 90 parts by mass in the urethane resin composition.

As the solvent (B), for example, ethyl acetate, methyl acetate, butyl acetate, acetone, methyl ethyl ketone, methyl isobutyl ketone, heptane, hexane, cyclohexane, methyl cyclohexane, toluene, o-xylene, m-xylene, p-xylene, methanol, ethanol, isopropanol, isobutanol, di-butanol, tertiary butanol, N,N,2-trimethylpropionamide, N,N-dimethylacrylamide, N,N-dimethylpropionamide, N,N-diethylacetamide, N,N-diethylacrylamide, 1,3-dimethyl-2-imidazolidinone, N-ethylpyrrolidone, 2-pyrrolidone, etc. These organic solvents may be used alone or in combination of two or more.

The content of the solvent (B) may be, for example, in the range of 10 to 90% by mass in the urethane resin composition.

The urethane resin composition contains the urethane resin (A), the solvent (B), and the film-forming aid (C) as essential components, but may contain other additives as necessary.

As the aforementioned other additives, for example, film-forming aids other than the aforementioned (c1), pigments, flame retardants, plasticizers, softeners, stabilizers, waxes, defoamers, dispersants, penetrants, surfactants, fillers, mold inhibitors, antibacterial agents, ultraviolet absorbers, antioxidants, weathering stabilizers, fluorescent whitening agents, anti-aging agents, thickeners, etc. can be used alone or in combination of two or more.

Next, a method for preparing a porous body by a wet film-forming method using the above-mentioned urethane resin composition is described.

The wet film-forming method is a method for producing a porous body by coating or impregnating the surface of a substrate with the urethane resin composition, and then bringing the coated surface or impregnated surface into contact with water, water vapor, etc. to solidify the urethane resin (A).

As the substrate on which the urethane resin composition is applied, for example, nonwoven fabrics, woven fabrics, knitted fabrics, resin films, etc. can be used. As the substrate, for example, chemical fibers such as polyester fibers, nylon fibers, acrylic fibers, polyurethane fibers, acetate fibers, rayon fibers, polylactic acid fibers, etc. can be used; cotton, linen, silk, wool, and blended fibers thereof can be used.

The surface of the aforementioned substrate may be subjected to anti-static treatment, mold release treatment, water repellent treatment, water absorption treatment, antibacterial and deodorizing treatment, antibacterial treatment, ultraviolet ray shielding treatment, etc., as necessary.

As a method for coating or impregnating the surface of the substrate with the urethane resin composition, for example, a gravure coating method, a knife coating method, a tube coating method, and a notch wheel coating method can be cited. At this time, in order to adjust the viscosity of the urethane resin composition and improve the coating workability, the amount of the organic solvent (B) used can be adjusted as needed.

The thickness of the coating film containing the urethane resin composition applied or impregnated by the above method is preferably in the range of 0.5 to 5 mm, more preferably in the range of 0.5 to 3 mm.

As a method for bringing the coated surface formed by coating or impregnation with the urethane resin composition into contact with water or water vapor, for example, a method of immersing the substrate provided with a coating layer or impregnation layer containing the urethane resin composition in a water bath; a method of spraying water on the coated surface using a sprayer, etc. For example, the immersion is carried out in a water bath at 5 to 60° C. for 2 to 20 minutes.

The porous body obtained by the above method is preferably washed with water at room temperature or warm water to extract and remove the solvent (B), and then dried. The above washing can be carried out, for example, with water at 5 to 60°C for 20 to 120 minutes, and the water used for washing is preferably replaced once or more, or continuously replaced with running water. The above drying is preferably carried out, for example, using a dryer adjusted to 80 to 120°C for 10 to 60 minutes.

According to the present invention, by using a specific film-forming aid and utilizing a wet film-forming method, a porous body with fine and uniform cells, a sense of weight, and a soft texture can be manufactured. Therefore, the present invention can be particularly suitably used in the manufacture of polishing pads, artificial leather, and synthetic leather. [Example]

The present invention is described in more detail below using examples.

[Synthesis Example 1] Synthesis of Urethane Resin (A-1) In a reaction apparatus equipped with a stirrer, a reflux, and a thermometer, 100 parts by mass of polyester polyol (reactant of ethylene glycol and adipic acid, number average molecular weight: 2,000), 20 parts by mass of 1,4-butanediol, 564 parts by mass of N,N-dimethylformamide, and 68 parts by mass of 4,4'-diphenylmethane diisocyanate were added, and the mixture was reacted at 60°C for 6 hours under stirring. Then, 1 part by mass of isopropyl alcohol was added, and the mixture was further stirred at 60°C for 1 hour to obtain a urethane resin composition. The obtained urethane resin composition had a solid content of 25% by mass, a viscosity of 600 dPa·s, and a weight average molecular weight of 188,100.

[Synthesis Example 2] Synthesis of Urethane Resin (A-2) In a reaction apparatus equipped with a stirrer, a reflux, and a thermometer, 100 parts by mass of polytetramethylene glycol (number average molecular weight: 2,000), 10 parts by mass of ethylene glycol, 380 parts by mass of N,N-dimethylformamide, and 53 parts by mass of 4,4'-diphenylmethane diisocyanate were added, and the mixture was reacted at 60°C for 6 hours under stirring. Then, 1 part by mass of isopropyl alcohol was added, and the mixture was further stirred at 60°C for 1 hour to obtain a urethane resin composition. The obtained urethane resin composition had a solid content of 30% by mass, a viscosity of 800 dPa·s, and a weight average molecular weight of 120,500.

[Method for determining number average molecular weight and weight average molecular weight] The number average molecular weight of the raw material polyol used in the synthesis example, the number average molecular weight of the polysilicone compound (c1), and the weight average molecular weight of the urethane resin (A) are the values measured by gel permeation chromatography (GPC) under the following conditions.

Measuring device: High-speed GPC device ("HLC-8220GPC" manufactured by Tosoh Co., Ltd.) Column: The following columns manufactured by Tosoh Co., Ltd. were connected in series for use. "TSKgel G5000" (7.8mmI.D.×30cm) × 1 tube "TSKgel G4000" (7.8mmI.D.×30cm) × 1 tube "TSKgel G3000" (7.8mmI.D.×30cm) × 1 tube "TSKgel G2000" (7.8mmI.D.×30cm) × 1 tube Detector: RI (differential refractometer) Column temperature: 40℃ Eluent: tetrahydrofuran (THF) Flow rate: 1.0mL/min Injection volume: 100μL (sample concentration 0.4 mass% tetrahydrofuran solution) Standard sample: Use the following standard polystyrene to make a calibration curve.

(Standard polystyrene) Tosoh Co., Ltd. "TSKgel Standard Polystyrene A-500" Tosoh Co., Ltd. "TSKgel Standard Polystyrene A-1000" Tosoh Co., Ltd. "TSKgel Standard Polystyrene A-2500" Tosoh Co., Ltd. "TSKgel Standard Polystyrene A-5000" Tosoh Co., Ltd. "TSKgel Standard Polystyrene F-1" Tosoh Co., Ltd. "TSKgel Standard Polystyrene F-2" Tosoh Co., Ltd. "TSKgel Standard Polystyrene F-4" Tosoh Co., Ltd. "TSKgel Standard Polystyrene F-10" Tosoh Co., Ltd. "TSKgel Standard Polystyrene F-20" Tosoh Co., Ltd. "TSKgel Standard Polystyrene F-40" Tosoh Co., Ltd. "TSKgel Standard Polystyrene F-80" Tosoh Co., Ltd. "TSKgel Standard Polystyrene F-128" Tosoh Co., Ltd. "TSKgel Standard Polystyrene F-288" Tosoh Co., Ltd. "TSKgel Standard Polystyrene F-550"

[Example 1] To 100 parts by mass of the urethane resin composition obtained in Synthesis Example 1, 40 parts by mass of N,N-dimethylformamide (hereinafter referred to as "DMF") and 2 parts by mass of a polysilicone compound having a hydroxyl group and an oxyethylene structure (hereinafter referred to as "EO structure") ("SF-8427" manufactured by Dow Corning Toray Co., Ltd., number average molecular weight 2,400, hereinafter referred to as "c1-1") were added to prepare a mixed solution, which was applied to a polyethylene terephthalate (PET) film in a manner to have a thickness (Wet) of 1 mm. Next, the coated substrate was immersed in a coagulation bath (water at 25°C) for 10 minutes to coagulate the urethane resin. Thereafter, the substrate was immersed in water at 50°C for 60 minutes to wash off the solvent. After washing, the substrate was dried with hot air at 100° C. for 30 minutes to obtain a porous body.

[Example 2] Except that in Example 1, a polysilicone compound having a hydroxyl group and an oxyethylene structure ("KF-6123" manufactured by Shin-Etsu Chemical Co., Ltd., number average molecular weight 2,200, hereinafter referred to as "c1-2") was used instead of c1-1, the same process as in Example 1 was followed to obtain a porous body.

[Example 3] Except that in Example 1, the urethane resin composition obtained in Synthesis Example 2 is used instead of the urethane resin composition obtained in Synthesis Example 1, the same procedure as in Example 1 is followed to obtain a porous body.

[Comparative Example 1] Except that in Example 1, a polysilicone compound having a hydroxyl group ("KF-6001" manufactured by Shin-Etsu Chemical Co., Ltd., number average molecular weight 1,800, hereinafter referred to as "cR1-1") was used instead of c1-1, the same procedure as in Example 1 was followed to obtain a porous body.

[Comparative Example 2] Except that dodecylbenzenesulfonic acid (hereinafter referred to as "DBS") was used instead of c1-1 in Example 1, the same process as Example 1 was carried out to obtain a porous body.

[Evaluation method of wet film-forming properties] The cross-section of the porous body obtained in the example was observed with a scanning electron microscope "JSM-IT500" manufactured by JEOL Ltd. (magnification: 100 times) to confirm the cell shape (fineness, uniformity). If the cells with a maximum width of 70 μm or less accounted for 60% of the total, the evaluation was "○", and the others were evaluated as "×".

[Texture evaluation method] For the porous body obtained in the embodiment, the texture was checked by touching with fingers. If there was a sense of weight and rebound, it was evaluated as "○", and otherwise it was evaluated as "×".

[Table 1] Table 1 Embodiment 1 Embodiment 2 Embodiment 3 Comparison Example 1 Comparison Example 2 Types of urethane resin (A) (A-1) (A-1) (A-2) (A-1) (A-1) Film-forming aid (C) Type c1-1 c1-2 c1-1 cR1-1 DBS Whether there is an EO structure have have have without - The presence or absence of hydroxyl groups have have have have - Number average molecular weight 2,400 2,200 2,400 1,800 - Content (relative to 100 parts by mass of urethane resin (A)) 8 8 6.7 8 8 Evaluation of wet film forming properties ○ ○ ○ × × Quality Evaluation ○ ○ ○ × ×

The porous body obtained by the manufacturing method of the present invention has fine and uniform cells and excellent quality.

On the other hand, in Comparative Example 1, a polysilicone compound without an oxyethylene structure was used instead of the polysilicone compound (c1) as a film-forming aid, but the porous cells were poorly formed and the texture was also poor.

Comparative Example 2 is an embodiment in which dodecylbenzenesulfonic acid is used as a film-forming aid instead of the polysilicone compound (c1), but the porous cells are poorly formed and the texture is also poor.

without.

without.

without.

Claims (3)

A method for producing a porous body, which is a method for producing a porous body by wet film formation of a urethane resin composition containing a urethane resin (A), a solvent (B), and a film-forming aid (C), wherein the urethane resin (A) is prepared according to a step comprising reacting a polyol (a1), a polyisocyanate (a2), and a chain extender (a1-1) in a solvent containing N,N-dimethylformamide, and adding a solvent selected from methanol, ethanol, isopropanol, The porous body is obtained by a method of adding one or more solvents selected from the group consisting of isobutyl alcohol, dibutyl alcohol and tertiary butyl alcohol and stirring; the film-forming aid (C) is a polysilicone compound (c1) having an oxyethylene structure; the number average molecular weight of the polysilicone compound (c1) is in the range of 500 to 5,000; the method for manufacturing the porous body comprises the steps of coating or impregnating the urethane resin composition on the surface of the substrate, and contacting the coated surface or impregnated surface with water or water vapor. The method for manufacturing a porous body as claimed in claim 1, wherein the polysilicone compound (c1) further has a hydroxyl group. The method for producing a porous body according to claim 1 or 2, wherein the content of the polysilicone compound (c1) is in the range of 0.1 to 30 parts by weight relative to 100 parts by weight of the urethane resin (A).