JP7331453B2 - Method for manufacturing porous body - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a porous body by a wet film-forming method.

Polishing pads using urethane resin compositions are widely used in fields requiring a high degree of surface flatness, such as liquid crystal glass, hard disk glass, silicon wafers, and semiconductors. Among them, in the final polishing, a soft porous body processed by a wet film forming method in which urethane resin diluted with a solvent such as DMF (dimethylformamide) is solidified in water is used (for example, Patent Document 1 ).

The properties required for this porous polishing pad include, for example, a high bulk modulus (=low compressibility) to maintain the flatness of the surface of the workpiece, and a material that suppresses scratches on the surface. and the fineness and uniformity (wet film-forming property) of porous cells responsible for holding slurry (polishing liquid) and stable polishing.

One factor that satisfies these required properties is the uniformity and fineness of the porous cells in the polishing pad. However, obtaining such a polishing pad was not an easy task.

JP-A-2004-256738

The problem to be solved by the present invention is to provide a method for producing a porous body having fine and uniform cells by a wet film-forming method.

The present invention provides a method for producing a porous body by wet film-forming of a urethane resin composition containing a urethane resin (A), a solvent (B), and a film-forming aid (C), wherein the film-forming A method for producing a porous body, wherein the auxiliary agent (C) is a polyol (c1) having a polyoxypropylene structure and having an average number of hydroxyl groups of more than 2 and not more than 4 per molecule. is.

According to the present invention, a fine and uniform porous body can be produced by a wet film-forming method by using a specific film-forming aid. Therefore, the present invention can be used particularly preferably for manufacturing polishing pads, artificial leathers and synthetic leathers.

In the present invention, the "porous body" refers to a body having a large number of pores which can be naturally obtained by solidifying a urethane resin composition by a wet film-forming method. It refers to those that form a spindle-shaped or teardrop-shaped porous structure.

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

In the present invention, it is essential to use a polyol (c1) having a polyoxypropylene structure and having an average number of hydroxyl groups of more than 2 and 4 or less per molecule as the film forming aid (C). Since the polyol (c1) has high hydrophobicity, the coagulation speed of the urethane resin becomes mild, and the porous cells become fine and uniform. The average number of hydroxyl groups of the polyol (c1) is preferably in the range of 2.5 to 3.5 from the viewpoint of enabling more excellent porous cell formation.

Examples of the polyol (c1) include, for example, an adduct of glycerin and propylene oxide; a product obtained by adding propylene oxide to glycerin as an initiator and then adding ethyne oxide to the end thereof; using glycerin as an initiator and propylene Reactions of glycerin, propylene oxide and ethylene oxide, such as adducts of mixtures of oxide and ethylene oxide; adducts of trimethylolpropane and propylene oxide; trimethylolpropane as initiator, after addition of propylene oxide, A reaction product of trimethylolpropane, propylene oxide and ethylene oxide, such as a product obtained by adding an ethyne oxide to the end thereof, or a product obtained by adding a mixture of propylene oxide and ethylene oxide using trimethylolpropane as an initiator, may be used. can. Among these, it is preferable to use an adduct of glycerin and propylene oxide and/or an adduct of trimethylolpropane and propylene oxide from the point of being able to form more excellent porous cells.

The number average molecular weight of the polyol (c1) is preferably in the range of 450 to 10,000, more preferably in the range of 1,000 to 7,000, from the viewpoint of forming more excellent porous cells. The number average molecular weight of the polyol (c1) is a value measured under the following conditions by a gel permeation chromatography (GPC) method.

The content of the polyol (c1) is preferably in the range of 0.1 to 30 parts by mass with respect to 100 parts by mass of the urethane resin (A), in order to form more excellent porous cells. , more preferably in the range of 0.5 to 20 parts by mass.

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. can be used. These polyols may be used alone or in combination of two or more.

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, from the viewpoint of the mechanical properties and flexibility of the porous body. . The number average molecular weight of the polyol (a1) is the 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. As the chain extender (a1-1), for example, a chain extender having a hydroxyl group, a chain extender having an amino group, or the like can be used. These chain extenders (a1-1) may be used alone or in combination of two or more.

Examples of the chain extender having a hydroxyl group include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, hexamethylene glycol, Aliphatic polyol compounds such as sucrose, methylene glycol, glycerin, sorbitol; bisphenol A, 4,4'-dihydroxydiphenyl, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl sulfone, hydrogenated bisphenol A, hydroquinone, etc. of aromatic polyol compounds; water and the like can be used. These chain extenders may be used alone or in combination of two or more.

Examples of the chain extender having an amino group include ethylenediamine, 1,2-propanediamine, 1,6-hexamethylenediamine, piperazine, 2-methylpiperazine, 2,5-dimethylpiperazine, isophoronediamine, 4,4 '-dicyclohexylmethanediamine, 3,3'-dimethyl-4,4'-dicyclohexylmethanediamine, 1,2-cyclohexanediamine, 1,4-cyclohexanediamine, aminoethylethanolamine, hydrazine, diethylenetriamine, triethylenetetramine, etc. can be used. These chain extenders may be used alone or in combination of two or more.

Examples of the polyisocyanate (a2) include 4,4′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, carbodiimide-modified diphenylmethane diisocyanate, crude diphenylmethane diisocyanate, phenylene diisocyanate, triene diisocyanate, naphthalene diisocyanate, xylylene diisocyanate, tetra Aromatic polyisocyanates such as methylxylylene diisocyanate; Aliphatic polyisocyanates such as hexamethylene diisocyanate and lysine diisocyanate; Alicyclic polyisocyanates such as cyclohexane diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate and dicyclohexylmethane diisocyanate; can be done. These polyisocyanates may be used alone or in combination of two or more.

As a method for producing the urethane resin (A), for example, the polyol (a1), the polyisocyanate (a2) and, if necessary, the chain extender (a1-1) are charged and reacted. method. These reactions are preferably carried out at a temperature of 50 to 100° C. for approximately 3 to 10 hours. Moreover, you may perform the said reaction in the solvent (B) mentioned later.

The molar ratio of the sum of the hydroxyl groups of the polyol (a1) and the hydroxyl groups and amino groups of the chain extender (a1-1) to the isocyanate groups 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.

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 from the viewpoint of the mechanical strength and flexibility of the porous body. A range of 000 to 500,000 is more preferred. The weight average molecular weight of the urethane resin (A) is the value obtained by measuring in the same manner as the number average molecular weight of the polyol (a1).

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

Examples of the solvent (B) include ethyl acetate, methyl acetate, butyl acetate, acetone, methyl ethyl ketone, methyl isobutyl ketone, heptane, hexane, cyclohexane, methylcyclohexane, toluene, o-xylene, m-xylene, p-xylene, methanol, ethanol, isopropyl alcohol, isobutanol, sec-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 and the like can be used. These organic solvents may be used alone or in combination of two or more.

The content of the solvent (B) is, 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, and optionally contains other additives. may

Examples of the other additives include film formation aids other than (c1), pigments, flame retardants, plasticizers, softeners, stabilizers, waxes, antifoaming agents, dispersants, penetrants, and surfactants. , a filler, an antifungal agent, an antibacterial agent, an ultraviolet absorber, an antioxidant, a weather stabilizer, a fluorescent whitening agent, an antiaging agent, a thickener, and the like. These additives may be used alone or in combination of two or more.

Next, a method for producing a porous body from the urethane resin composition by a wet film-forming method will be described.

In the wet film-forming method, the urethane resin composition is applied or impregnated onto the surface of a base material, and then the urethane resin (A) is solidified by bringing the coated surface or the impregnated surface into contact with water, steam, or the like. This is a method for producing a strained porous body.

As the base material to which the urethane resin composition is applied, for example, a base material made of a nonwoven fabric, a woven fabric, or a knitted fabric; a resin film or the like can be used. Chemical fibers such as polyester fiber, nylon fiber, acrylic fiber, polyurethane fiber, acetate fiber, rayon fiber, and polylactic acid fiber; cotton, hemp, silk, wool, and blended fibers thereof. etc. can be used.

If necessary, the surface of the base material may be subjected to antistatic treatment, release treatment, water repellent treatment, water absorption treatment, antibacterial deodorant treatment, antibacterial treatment, ultraviolet shielding treatment, and the like.

Examples of the method of applying or impregnating the urethane resin composition onto the substrate surface include gravure coater method, knife coater method, pipe coater method, and comma coater method. At that time, the amount of the organic solvent (B) used may be adjusted as necessary in order to adjust the viscosity of the urethane resin composition and improve the coating workability.

The thickness of the coating film made of 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 of bringing water or steam into contact with the coated surface formed by coating or impregnating the urethane resin composition, for example, a substrate provided with a coating layer or an impregnated layer made of the urethane resin composition is immersed in a water bath. a method of spraying water onto the coating surface using a spray or the like. The immersion is performed, for example, in a water bath at 5 to 60° C. for 2 to 20 minutes.

The surface of 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 washing may be carried out, for example, with water of 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 drying is preferably carried out for 10 to 60 minutes using, for example, a dryer adjusted to 80 to 120°C.

As described above, according to the present invention, a fine and uniform porous body can be produced by a wet film-forming method by using a specific film-forming aid. Therefore, the present invention can be used particularly preferably for manufacturing polishing pads, artificial leathers and synthetic leathers.

The present invention will be described in more detail below using examples.

[Synthesis Example 1] Synthesis of urethane resin (A-1) 100 mass of polyester polyol (reaction product of ethylene glycol and adipic acid, number average molecular weight: 2,000) was placed in a reactor equipped with a stirrer, a reflux device, and a thermometer. parts, 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, and reacted at 60° C. for 6 hours with stirring, Subsequently, 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 resulting 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.

[Method for measuring number average molecular weight/weight average molecular weight]
The number average molecular weight of the raw material polyol, the number average molecular weight of the polyol (c1), and the weight average molecular weight of the urethane resin (A) used in Synthesis Examples were measured by gel permeation chromatography (GPC) under the following conditions. value.

Measuring device: High-speed GPC device ("HLC-8220GPC" manufactured by Tosoh Corporation)
Column: The following columns manufactured by Tosoh Corporation were connected in series and used.
"TSKgel G5000" (7.8mm I.D. x 30cm) x 1 "TSKgel G4000" (7.8mm I.D. x 30cm) x 1 "TSKgel G3000" (7.8mm I.D. x 30cm) x 1 Book "TSKgel G2000" (7.8 mm I.D. x 30 cm) x 1 Detector: RI (differential refractometer)
Column temperature: 40°C
Eluent: Tetrahydrofuran (THF)
Flow rate: 1.0 mL/min Injection volume: 100 μL (tetrahydrofuran solution with a sample concentration of 0.4% by mass)
Standard sample: A calibration curve was created using the following standard polystyrene.

(standard polystyrene)
"TSKgel standard polystyrene A-500" manufactured by Tosoh Corporation
"TSKgel standard polystyrene A-1000" manufactured by Tosoh Corporation
"TSKgel standard polystyrene A-2500" manufactured by Tosoh Corporation
"TSKgel standard polystyrene A-5000" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-1" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-2" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-4" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-10" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-20" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-40" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-80" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-128" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-288" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-550" manufactured by Tosoh Corporation

[Example 1]
Per 100 parts by mass of the urethane resin composition obtained in Synthesis Example 1, 40 parts by mass of N,N-dimethylformamide (hereinafter abbreviated as "DMF") and polypropylene triol ("Exenol 3030" manufactured by AGC Co., Ltd. , number of functional groups: 3, number average molecular weight of 3,000, hereinafter abbreviated as “c1-1”.) to prepare a blended solution, and polyethylene terephthalate ( PET) film. Then, the coated substrate was immersed in a coagulation bath (25° C. water) for 10 minutes to coagulate the urethane resin. After that, 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]
In Example 1, instead of c1-1, polypropylene triol ("Exenol 2030" manufactured by Asahi Glass Urethane Co., Ltd., number of functional groups: 3, number average molecular weight: 2,000, hereinafter abbreviated as "c1-2") was used. A porous body was obtained in the same manner as in Example 1, except that it was used.

[Example 3]
In Example 1, instead of c1-1, polypropylene triol ("Exenol 5030" manufactured by Asahi Glass Urethane Co., Ltd., number of functional groups: 3, number average molecular weight: 5,000, hereinafter abbreviated as "c1-3") was used. A porous body was obtained in the same manner as in Example 1, except that it was used.

[Comparative Example 1]
In Example 1, instead of c1-1, polypropylene glycol (“Exenol 3020” manufactured by Asahi Glass Urethane Co., Ltd., number of functional groups: 2, number average molecular weight of 3,200, hereinafter abbreviated as “cR1-1”) was used. A porous body was obtained in the same manner as in Example 1, except that it was used.

[Comparative Example 2]
A porous body was obtained in the same manner as in Example 1, except that dodecylbenzenesulfonic acid (hereinafter abbreviated as "DBS") was used instead of c1-1.

[Method for evaluating wet film formability]
The cross-sectional state of the porous body obtained in the example was observed with a scanning electron microscope "JSM-IT500" manufactured by JEOL Ltd. (magnification: 100 times), and the cell shape (fineness, uniformity) was confirmed. If cells with a maximum lateral width of 70 μm or less accounted for 60% of the total, they were evaluated as “◯”, and otherwise as “X”.

[Evaluation method of compression rate]
The porous bodies obtained in Examples were evaluated for compressibility in accordance with JISL-1021-6. Specifically, the “thickness under standard pressure: t0” after applying an initial load of 2 kPa for 30 seconds was measured, and then the “thickness under constant pressure” after applying a final load of 98 kPa for 30 seconds. t1” was measured and applied to the following formula to calculate the compression rate.
Compression rate (%) = 100 x (t0-t1)/t0
If the obtained compression rate was 20% or less, it was evaluated as "good", and otherwise as "poor".

It was found that the porous body obtained by the production method of the present invention has fine and uniform cells and is excellent in low compressibility.

On the other hand, Comparative Example 1 is an embodiment in which a polyol having an average number of hydroxyl groups of 2 was used instead of the polyol (c1) as a film-forming aid, but the formation of porous cells was poor and the low compressibility was also poor. Met.

Comparative Example 2 is an embodiment in which dodecylbenzenesulfonic acid was used instead of the polyol (c1) as the film-forming aid.

Claims (6)

A method for producing a porous body by wet film-forming of a urethane resin composition containing a urethane resin (A), a solvent (B), and a film-forming aid (C), comprising:
The film-forming aid (C) is a polyol (c1) having a polyoxypropylene structure and an average number of hydroxyl groups per molecule exceeding 2 and 4 or less,
A method for producing a porous body , wherein the polyol (c1) contains an adduct of glycerin and propylene oxide . 2. The method for producing a porous body according to claim 1, wherein the urethane resin (A) contains a polyol (a1) containing a polyester polyol as an essential raw material. The urethane resin (A) further contains a chain extender (a1-1) having a number average molecular weight of less than 500 as an essential raw material, and the chain extender (a1-1) contains an aliphatic polyol compound. 2. The method for producing a porous body according to claim 1, wherein 2. The method for producing a porous body according to claim 1, wherein the urethane resin (A) has a weight average molecular weight in the range of 10,000 to 500,000. 2. The method for producing a porous body according to claim 1, wherein the polyol (c1) has a number average molecular weight in the range of 450 to 10,000. The production of the porous body according to any one of claims 1 to 5, wherein the content of the polyol (c1) is in the range of 0.1 to 30 parts by mass with respect to 100 parts by mass of the urethane resin (A). Method.