KR20160067135A - Porous body and polishing pad - Google Patents

Abstract

A problem to be solved by the present invention is to provide a porous article which is hardly closed in a cell during dressing or polishing. The present invention relates to a urethane resin (A) obtained by reacting a polyol (a1), a polyisocyanate (a2) and a chain extender (a3) containing an aromatic polyester polyol (a1-1) in an amount of 5 to 80 mass% A porous article obtained by processing a urethane resin composition containing an organic solvent (B) by a wet film-forming method, and a polishing pad characterized by being obtained by dressing it. The porous article of the present invention can be used particularly favorably as a polishing pad and can reduce the addition amount of carbon black used for improving abrasive life and polishing rate and for improving abrasiveness at the time of polishing , Scratches during polishing can be reduced.

Description

Porous body and polishing pad {POROUS BODY AND POLISHING PAD}

The present invention relates to a porous article which can be used, for example, in a leather-like sheet such as synthetic leather or artificial leather, a breathable waterproofing material, a polishing pad or the like.

BACKGROUND OF THE INVENTION [0002] Polishing pads using urethane resin compositions are widely used in fields requiring high surface flatness such as liquid crystal glass, hard disk glass, silicon wafers, and semiconductors. Among them, a porous body processed by a wet film-forming method in which a urethane resin diluted with a solvent such as DMF (dimethylformamide) is coagulated in water is used in final polishing. The surface of the porous body is cut by a dresser (dressing process), and the porous cell is opened to form a polishing pad.

As the polishing pad, there is disclosed a polishing pad obtained by processing a urethane resin composition using a polyether polyol as a raw material by a wet film forming method (see, for example, Patent Document 1). However, the polishing pad has a problem in that when the dressing is performed, the fine cells are easily clogged and the polishing rate is lowered. Further, even at the time of polishing, the fine cells are liable to be clogged and the polishing rate is lowered. In addition, although the wet porous article for a polishing pad has carbon black added to improve abrasion resistance, scratches due to agglomeration of carbon have also been a problem.

Japanese Patent Application Laid-Open No. 2007-169486

A problem to be solved by the present invention is to provide a porous article in which a cell is difficult to be closed (hereinafter abbreviated as " enclosed porosity ") at the time of dressing or polishing will be.

The present invention relates to a urethane resin (A) obtained by reacting a polyol (a1), a polyisocyanate (a2) and a chain extender (a3) containing an aromatic polyester polyol (a1-1) in an amount of 5 to 80 mass% A porous article obtained by processing a urethane resin composition containing an organic solvent (B) by a wet film-forming method, and a polishing pad characterized by being obtained by dressing it.

The term " porous " of the porous article of the present invention means that the urethane resin composition has a large number of holes naturally obtained by solidifying the urethane resin composition by the wet film forming method.

The porous article of the present invention is excellent in durability and abrasion resistance even when dressing or polishing. Further, since the porous article of the present invention has flexibility, it can be used as a skin layer or an intermediate layer of a leather-like sheet such as synthetic leather or artificial leather used for medical, vehicle seat, furniture sheet, shoes, Polishing pad; A polishing back pad; Medical sanitary materials such as surgical (surgical) and bed sheets; Sheets for building materials such as windshields, waterproof sheets and condensation prevention sheets; A packaging material such as a desiccant, a dehumidifying agent, and a fragrance; It can be used for various purposes such as an intermediate layer and a skin layer constituting agricultural sheets, various kinds of separators, packings and the like.

Among them, the porous article of the present invention can be used particularly favorably as a polishing pad, and it is possible to reduce the addition amount of carbon black used for improving abrasive life and polishing rate and for improving abrasion at the time of polishing So that scratches during polishing can be reduced.

The urethane resin composition used in the present invention is obtained by reacting a polyol (a1), a polyisocyanate (a2) and a chain extender (a3) containing an aromatic polyester polyol (a1-1) in an amount of 5 to 80 mass% And contains the urethane resin (A) and the organic solvent (B).

As the aromatic polyester polyol (a1-1), for example, a reaction product of a compound having a hydroxyl group and a polybasic acid containing an aromatic polybasic acid can be used suitably.

Examples of the compound having a hydroxyl group include ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, heptanediol, octanediol, nonanediol, decanediol, trimethylolpropane, trimethylolethane and glycerin have. These compounds may be used alone or in combination of two or more.

Examples of the aromatic polybasic acid include phthalic acid compounds such as phthalic acid, isophthalic acid, terephthalic acid and orthophthalic acid; Trimellitic anhydride, 1,2,5-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, pyromellitic acid, and pyromellitic anhydride can be used. These aromatic polybasic acids may be used alone or in combination of two or more. Among them, it is preferable to use a phthalic acid compound in order to further improve the air entrapping porosity.

The aromatic polybasic acid may be used in combination with other polybasic acids other than the aromatic polybasic acid for the purpose of adjusting the viscosity or hardness of the urethane resin composition. Examples of the other polybasic acids include oxalic acid, malonic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, 1,12-dodecanedicarboxylic acid, and the like. These polybasic acids may be used alone or in combination of two or more.

The content of the aromatic polybasic acid in the polybasic acid used as the raw material of the aromatic polyester polyol (a1-1) is preferably 20% by mass or more, more preferably 20% by mass or more, in view of being able to further improve the viscosity, hardness, More preferably 30% by mass or more, and still more preferably 40% by mass or more.

The number average molecular weight of the aromatic polyester polyol (a1-1) is preferably in the range of 500 to 5,000, more preferably in the range of 800 to 4,000, and more preferably in the range of 900 to 3,000, Is more preferable. The number average molecular weight of the aromatic polyester polyol (a1-1) is a value obtained by measuring by the gel permeation chromatography (GPC) under the following conditions.

Measurement apparatus: High-speed GPC apparatus ("HLC-8220GPC" manufactured by Tosoh Corporation)

Column: The following columns of Tosoh Corporation were connected in series.

 "TSKgel G5000" (7.8 mm ID × 30 cm) × 1

 "TSKgel G4000" (7.8 mm ID × 30 cm) × 1

 "TSKgel G3000" (7.8 mm ID × 30 cm) × 1

 "TSKgel G2000" (7.8 mm I.D. × 30 cm) × 1

Detector: RI (differential refractometer)

Column temperature: 40 DEG C

Eluent: tetrahydrofuran (THF)

Flow rate: 1.0 ml / min

Injection amount: 100 占 퐇 (tetrahydrofuran solution with 0.4 mass% of sample concentration)

Standard sample: A calibration curve was prepared using the following standard polystyrene.

(Standard polystyrene)

Quot; TSKgel Standard Polystyrene A-500 " manufactured by Tosoh Corporation

Quot; TSKgel standard polystyrene A-1000 " manufactured by Tosoh Corporation

Quot; TSKgel Standard Polystyrene A-2500 " manufactured by Tosoh Corporation

Quot; TSKgel Standard Polystyrene A-5000 " manufactured by Tosoh Corporation

Quot; TSKgel standard polystyrene F-1 " manufactured by Tosoh Corporation

Quot; TSKgel standard polystyrene F-2 " manufactured by Tosoh Corporation

Quot; TSKgel standard polystyrene F-4 " manufactured by Tosoh Corporation

Quot; TSKgel standard polystyrene F-10 " manufactured by Tosoh Corporation

Quot; TSKgel standard polystyrene F-20 " manufactured by Tosoh Corporation

Quot; TSKgel standard polystyrene F-40 " manufactured by Tosoh Corporation

Quot; TSKgel standard polystyrene F-80 " manufactured by Tosoh Corporation

Quot; TSKgel standard polystyrene F-128 " manufactured by Tosoh Corporation

Quot; TSKgel standard polystyrene F-288 " manufactured by Tosoh Corporation

Quot; TSKgel standard polystyrene F-550 " manufactured by Tosoh Corporation

The content of the aromatic polyester polyol (a1-1) in the polyol (a1) is required to be in the range of 5 to 80% by mass. When the content is within the above range, the crystallinity of the soft segment in the polyurethane becomes very good, and a suitable brittleness is obtained, so that a porous article having excellent air entrapping porosity can be obtained. When the content is less than 5 mass%, the crystallinity of the soft segment is low, and the desired antistatic property can not be obtained. When the content is more than 80 mass%, the crystallinity of the soft segment is excessively high, The cell is likely to be closed. The content is preferably in the range of 10 to 70 mass%, more preferably in the range of 15 to 60 mass%, from the standpoint of further improving the air entraining property.

Examples of the polyol (a1) usable in addition to the aromatic polyester polyol (a1-1) include aliphatic polyester polyols, polyether polyols, polycarbonate polyols, polycaprolactone polyols, polyacrylic polyols, dimer diols, poly Butadiene polyol, hydrogenated polybutadiene polyol, and the like. These polyols may be used alone or in combination of two or more. Among these, from the viewpoint that the viscosity, hardness and mechanical strength of the urethane resin composition can be further improved while maintaining excellent air entrapping porosity, it is preferred to use one kind selected from the group consisting of aliphatic polyester polyol, polyether polyol and polycarbonate polyol Or more of the polyol is preferably used.

As the aliphatic polyester polyol, for example, a reaction product of the compound having a hydroxyl group and the other polybasic acid which can be used as a raw material of the aromatic polyester polyol can be preferably used.

The polyether polyol includes, for example, polyoxyethylene polyol, polyoxypropylene polyol, polyoxytetramethylene polyol, polyoxyethylene polyoxypropylene polyol, polyoxyethylene polyoxy tetramethylene polyol, polyoxypropylene polyoxy tetramethylene Polyol and the like can be used. These polyether polyols may be used alone or in combination of two or more.

As the polycarbonate polyol, for example, those obtained by reacting a carbonic acid ester and / or phosgene with a compound having two or more hydroxyl groups can be used.

As the carbonic ester, for example, methyl carbonate, dimethyl carbonate, ethyl carbonate, diethyl carbonate, cyclocarbonate, diphenyl carbonate and the like can be used. These carbonic esters may be used alone or in combination of two or more.

Examples of the compound having two or more hydroxyl groups include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, Propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,5-hexanediol, 5-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 2 Methyl-1,3-propanediol, neopentyl glycol, 2-butyl-2-ethyl-1,3-propanediol, 3- , 2-methyl-1,8-octanediol, and other aliphatic polyols; Alicyclic polyols such as 1,2-cyclobutanediol, 1,3-cyclopentanediol, 1,4-cyclohexanedimethanol, cycloheptanediol, cyclooctanediol, and hydroxypropylcyclohexanol; Aromatic polyols such as bisphenol A, bisphenol F, and 4,4'-biphenol, and the like. These compounds may be used alone or in combination of two or more.

The number average molecular weight of the aliphatic polyester polyol, polyether polyol and polycarbonate polyol is preferably from 500 to 5,000, more preferably from 500 to 5,000, from the viewpoint that the viscosity, hardness and mechanical strength of the urethane resin composition can be further improved while maintaining excellent anti- More preferably in the range of 800 to 4,000, and more preferably in the range of 900 to 3,000. The number average molecular weight of the aliphatic polyester polyol, the polyether polyol and the polycarbonate polyol represents a value obtained by measurement in the same manner as the number average molecular weight of the aromatic polyester polyol (a1-1).

Examples of the polyisocyanate (a2) include 1,3- and 1,4-phenylene diisocyanate, 1-methyl-2,4-phenylene diisocyanate, 1-methyl- Methyl-3,5-phenylene diisocyanate, 1-methyl-3,5-phenylene diisocyanate, 1-methyl- Dimethyl-2,4-phenylene diisocyanate, 1,3-dimethyl-4,6-phenylene diisocyanate, 1,4-dimethyl-2,5-phenylene diisocyanate, diethylbenzene diisocyanate, diisopropylbenzene Methyl-3,5-diethylbenzene diisocyanate, 3-methyl-1,5-diethylbenzene-2,4-diisocyanate, 1,3,5-triethylbenzene- 1,4-diisocyanate, naphthalene-1,5-diisocyanate, 1-methyl-naphthalene-1,5-diisocyanate, naphthalene-2,6-diisocyanate Naphthalene-2,7-diisocyanate, 1,1-dinaphthyl-2,2'-diisocyanate, biphenyl-2,4'-diisocyanate, biphenyl-4,4'-diisocyanate, 3 3'-dimethylbiphenyl-4,4'-diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, diphenylmethane-2,4-diisocyanate and the like Aromatic polyisocyanates; But are not limited to, tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, dodecamethylene diisocyanate, trimethylhexamethylene diisocyanate, 1,3-cyclopentylene diisocyanate, 1,3-cyclohexylene diisocyanate, (Isocyanatomethyl) cyclohexane, 1,4-di (isocyanatomethyl) cyclohexane, lysine diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, Aliphatic or alicyclic polyisocyanates such as 2,4'-dicyclohexylmethane diisocyanate, 2,2'-dicyclohexylmethane diisocyanate and 3,3'-dimethyl-4,4'-dicyclohexylmethane diisocyanate, Etc. may be used. These polyisocyanates may be used alone or in combination of two or more. Among these, aromatic polyisocyanates are preferably used, and 4,4'-diphenylmethane diisocyanate is more preferable in that it is possible to further improve air entraining property and flexibility.

As the above-described chain extender (a3), for example, there can be used a chain extender having a hydroxyl group or a chain extender having an amino group. These make-up preparations 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 methylene glycol, glycerin and sorbitol; Aromatic polyol compounds such as bisphenol A, 4,4'-dihydroxydiphenyl, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl sulfone, hydrogenated bisphenol A and hydroquinone ; Water or the like can be used. These make-up preparations may be used alone or in combination of two or more.

Examples of the chain extender having the 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 and the like can be used. These make-up preparations may be used alone or in combination of two or more.

As the above-described chain extender (a3), it is preferable to use a chain extender having a hydroxyl group in view of suppressing discoloration over time and further improving flexibility, and aliphatic polyol compounds are more preferable Do.

The amount of the chain extender (a3) to be used is preferably 0.5 to 30 parts by mass, more preferably 1 to 20 parts by mass, based on 100 parts by mass of the polyol (a1) .

Examples of the method for producing the urethane resin (A) include a method in which the polyol (a1), the polyisocyanate (a2) and the chain extender (a3) are introduced and reacted. The reaction may be carried out at a temperature of 50 to 100 占 폚 for 3 to 10 hours, for example. The above reaction may be carried out in an organic solvent (B) described later.

(Isocyanate group) / (hydroxyl group and / or amino group) of the hydroxyl group of the polyol (a1) and the hydroxyl group and / or amino group of the chain extender (a3) and the isocyanate group of the polyisocyanate (a2) )] Is preferably in the range of 0.8 to 1.2, more preferably in the range of 0.9 to 1.1 in terms of mechanical strength.

The weight average molecular weight of the urethane resin (A) obtained by the above method is preferably in the range of 5,000 to 500,000, more preferably in the range of 10,000 to 300,000, A range of 30,000 to 150,000 is more preferable. The weight average molecular weight of the urethane resin (A) is a value obtained by measurement in the same manner as the number average molecular weight of the aromatic polyester polyol (a1-1).

The content of the aromatic ring in the urethane resin (A) is preferably in a range of 100 to 2,700 mmol / kg, more preferably in a range of 200 to 2,700 mmol / kg, More preferably in the range of from 2 to 400 mols / kg, and more preferably in the range of from 400 to 2000 mmols / kg. The content of the aromatic ring refers to the content of aromatic rings relative to the total mass of each raw material constituting the urethane resin (A).

Examples of the organic solvent (B) include N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, methylethylketone, , Ketone solvents such as methyl isobutyl ketone; Ester solvents such as methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, isopropyl acetate, isobutyl acetate, isobutyl acetate, and dibutyl acetate; Alcohol solvents such as methanol, ethanol, isopropyl alcohol, butanol and the like can be used. These organic solvents may be used alone or in combination of two or more.

Of these, N, N-dimethylformamide is preferably used because it is highly soluble in the urethane resin (A) and water and is easily removed by drying with hot air. When the above-mentioned N, N-dimethylformamide is used, the content of the organic solvent (B) is preferably 70% by mass or more.

The content of the organic solvent (B) is preferably in the range of 30 to 90 mass%, more preferably in the range of 40 to 80 mass% in the urethane resin composition in terms of workability and viscosity in handling the urethane resin composition More preferable.

The urethane resin composition contains the urethane resin (A) and the organic solvent (B) as essential components, but may contain other additives as required.

Examples of other additives include pigments, flame retardants, plasticizers, softeners, stabilizers, waxes, defoaming agents, dispersants, penetrants, surfactants, fillers, antifungal agents, antimicrobial agents, ultraviolet absorbers, antioxidants, A weathering stabilizer, a fluorescent whitening agent, an antioxidant, a thickener, and the like. These additives may be used alone or in combination of two or more.

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

The wet film forming method is a method in which the urethane resin composition is coated or impregnated on the substrate surface and then the water or steam is brought into contact with the coated surface or the impregnated surface to coagulate the urethane resin (A) .

Examples of the base to which the urethane resin composition is applied include a base made of a nonwoven fabric, a woven fabric, and a knitted fabric; A resin film or the like can be used. Examples of the material constituting the base material include chemical fibers such as polyester fibers, nylon fibers, acrylic fibers, polyurethane fibers, acetate fibers, rayon fibers and polylactic acid fibers; Cotton, hemp, dog, wool, blend fibers of these, and the like.

The surface of the base material may be subjected to treatment such as antistatic treatment, release treatment, water-repellent treatment, absorption treatment, antibacterial deodorization, antibacterial treatment, ultraviolet ray shielding treatment and the like as necessary.

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

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

Examples of the method of contacting water or water vapor with a coating surface formed by applying or impregnating the urethane resin composition include a method of immersing a substrate provided with the urethane resin composition or the substrate provided with the impregnated layer in a water bath; And a method in which water is sprayed on the coated surface using a spray or the like. The immersion may be carried out, for example, in a water bath at 5 to 60 캜 for 2 to 20 minutes.

It is preferable that the porous article obtained by the above method is washed by using water or hot water at room temperature to remove the organic solvent (C), and then dried. The washing is preferably performed at a temperature of 5 to 60 DEG C for 20 to 120 minutes, and the water used for washing is preferably replaced at least once or continuously exchanged with running water (running water). The drying is preferably carried out for 10 to 60 minutes using a drier adjusted to 80 to 120 캜.

The porous article obtained by the above method has a porous structure of a long spindle shape or a cumulative shape in the thickness direction of the surface. The size of the hole may be appropriately adjusted depending on the application, but it is preferable that the diameter of the hole in the region where the width in the surface direction (thickness direction) is the largest is from 1 to 10 Mu m. The porous article obtained in the present invention is flexible and suitable for compression in the thickness direction because it has a long hole in the thickness direction and a uniform diameter in the surface direction and can be suitably used as a polishing pad. The thickness of the porous article is preferably from 0.45 to 1 mm, and more preferably from 0.45 to 0.7 mm, for use in a polishing pad or the like.

As described above, the porous article of the present invention is excellent in durability and abrasion resistance even when dressing or polishing. Further, the porous article of the present invention has flexibility, so that it can be used as a skin layer or an intermediate layer of a leather-like sheet such as synthetic leather or artificial leather used for medical, vehicle seat, furniture sheet, shoes, Polishing pad; A polishing back pad; Medical hygiene materials such as surgery, bed sheets and the like; Sheet for building materials such as windshield, waterproof sheet and condensation prevention sheet; A packaging material such as a desiccant, a dehumidifying agent, and a fragrance; It can be used for various purposes such as an intermediate layer and a skin layer constituting agricultural sheets, various kinds of separators, packings and the like.

Among them, the porous article of the present invention can be used particularly favorably as a polishing pad obtained by dressing, and can improve the polishing life and the polishing rate, and also can improve the abrasiveness at the time of polishing by adding the amount of carbon black It is possible to reduce scratches during polishing.

[Example]

Hereinafter, the present invention will be described in more detail using examples.

[Example 1]

20 parts by mass of an aromatic polyester polyol (obtained by reacting ethylene glycol and phthalic acid, number average molecular weight: 2,000, hereinafter abbreviated as " aromatic PEs-1 ") was added to a reactor equipped with a stirrer, a condenser, 80 parts by mass of a polyester polyol (obtained by reacting ethylene glycol and adipic acid, number average molecular weight 2,000, hereinafter abbreviated as "aliphatic PEs-1"), 8 parts by mass of ethylene glycol (hereinafter abbreviated as "EG" 357 parts by mass of N, N-dimethylformamide (hereinafter abbreviated as "DMF") and 45 parts by mass of 4,4'-diphenylmethane diisocyanate (hereinafter abbreviated as "MDI" (Hereinafter abbreviated as "IPA") was added in an amount of 1 part by mass and further stirred at 60 ° C for 1 hour to obtain a urethane resin composition . The urethane resin composition had a solid content of 30 mass% and a viscosity of 800 dPa 占 퐏. The urethane resin had a weight average molecular weight of 80,500 and an aromatic ring content of 660 mmol / kg.

40 parts by mass of DMF was added to 100 parts by mass of the resultant urethane resin composition, and 1 part by mass of surfactant " ASISTA SD-7 " for wet processing, manufactured by Dainippon Ink & And then immersed in water at 25 DEG C for 10 minutes to solidify the solution. Thereafter, the resultant was washed in hot water at 50 DEG C for 60 minutes and left in a dryer at 100 DEG C for 30 minutes to obtain a porous article.

[Example 2]

A urethane resin composition and a porous article were obtained in the same manner as in Example 1 except that the amount of the aromatic PEs-1 was changed from 20 mass parts to 50 mass parts and the amount of the aliphatic PEs-1 was changed from 80 mass parts to 50 mass parts . The urethane resin composition had a solid content of 30 mass% and a viscosity of 950 dPa 占 퐏. The urethane resin had a weight average molecular weight of 91,000 and an aromatic ring content of 1,660 mmol / kg.

[Comparative Example 1]

A urethane resin composition and a porous body were obtained in the same manner as in Example 1 except that the aromatic PEs-1 was not used and the amount of the aliphatic PEs-1 was changed from 80 parts by mass to 100 parts by mass. The urethane resin composition had a solid content of 30% by mass and a viscosity of 750 dPa 占 퐏, and the weight average molecular weight of the urethane resin was 82,000.

[Comparative Example 2]

A urethane resin composition and a porous article were obtained in the same manner as in Example 1 except that the amount of the aromatic PEs-1 was changed from 20 mass parts to 85 mass parts and the amount of the aliphatic PEs-1 was changed from 80 mass parts to 15 mass parts . The urethane resin composition had a solid content of 30% by mass and a viscosity of 1010 dPa 占 퐏. The urethane resin had a weight average molecular weight of 89,000 and an aromatic ring content of 2,820 mmol / kg.

[Evaluation method of intrusion resistance]

The porous article obtained in the Examples and Comparative Examples was subjected to the following Taber abrasion test.

Tester; YOSEIKI SEISAKUSHO Co., Ltd. Taber abrasion tester "Rotary Ablation Tester"

Abrasion wheel; CS-10

weight; 250 g of wear arm

Rotational speed; 70 revolutions per minute

The number of tests; 3,000 times

The surface of the porous article after the Taber abrasion test was observed using a scanning electron microscope " SU3500 " (magnification: 500 times) manufactured by Hitachi High-Technologies Corporation. In addition, it was evaluated as " T " when the closed portion was not confirmed on the surface of the porous body, and " F "

[Table 1]

It was found that Examples 1 and 2, which are the porous bodies of the present invention, have excellent antistatic properties.

On the other hand, in Comparative Examples 1 and 2, the use amount of the aromatic polyester polyol (a1-1) exceeded the range specified in the present invention, but all of the air entraining pores were poor.

Claims (4)

(A) obtained by reacting a polyol (a1), a polyisocyanate (a2) and a chain extender (a3) containing an aromatic polyester polyol (a1-1) in an amount of 5 to 80 mass% And an organic solvent (B) are processed by a wet film-forming method to obtain a porous article. The method according to claim 1,
Wherein the content of aromatic rings in the urethane resin (A) is in the range of 100 to 2,700 mmol / kg. The method according to claim 1,
Wherein the polyol (a1) further contains at least one polyol selected from the group consisting of an aliphatic polyester polyol, a polyether polyol and a polycarbonate polyol. A polishing pad obtained by dressing the porous article according to any one of claims 1 to 3.