JP5867653B2 - Porous body and polishing pad - Google Patents

Description

  The present invention relates to a porous body that can be used for leather-like sheets such as synthetic leather and artificial leather, moisture-permeable waterproof materials, polishing pads, and the like.

  In fields requiring high surface flatness such as liquid crystal glass, hard disk glass, silicon wafers, and semiconductors, polishing pads using urethane resin compositions are widely used. In particular, in the final finish polishing, a porous body processed by a wet film forming method in which a urethane resin diluted with a solvent such as DMF (dimethylformamide) is solidified in water is used. This porous body is a polishing pad by scraping the surface with a dresser (dressing process) and opening the porous cells.

  As the polishing pad, a polishing pad obtained by processing a urethane resin composition using polyether polyol as a raw material by a wet film forming method is disclosed (for example, see Patent Document 1). However, the polishing pad has a problem that when the dressing process is performed, the fine cells are easily blocked, resulting in a decrease in the polishing rate. Further, even during polishing, the fine cells are easily clogged, resulting in a decrease in polishing life. Furthermore, although carbon black is added to the wet porous body for polishing pad in order to improve the wear properties, scratches due to carbon aggregation are also a problem.

JP 2007-169486 A

  The problem to be solved by the present invention is to provide a porous body in which cells do not easily close during dressing or polishing (hereinafter abbreviated as “close resistance”).

The present invention contains the aromatic polyester polyol (a1-1) in the range of 5 to 80% by mass , and further contains one or more polyols selected from the group consisting of aliphatic polyester polyols, polyether polyols and polycarbonate polyols. Obtained by processing a urethane resin (A) obtained by reacting a polyol (a1), a polyisocyanate (a2), and a chain extender (a3) with an organic solvent by a wet film forming method . the multi-hole body to a polishing pad which is characterized by being obtained by dress machining.

  The “porous” of the porous body of the present invention means that the urethane resin composition has a number of pores that are naturally obtained when the urethane resin composition is solidified by a wet film-forming method.

  The porous body of the present invention is excellent in durability and wear resistance because the cell is hardly closed even during dressing or polishing. Moreover, since the porous body of the present invention also has flexibility, the skin layer and intermediate layer of leather-like sheets such as synthetic leather and artificial leather used for clothing, vehicle seats, furniture sheets, shoes, bags, etc .; polishing pad ; Back pad for polishing; Medical hygiene materials such as surgical clothing and bed sheets; Sheets for building materials such as windproof and waterproof sheets and anti-condensation sheets; Packaging materials such as desiccants, dehumidifiers and fragrances; In addition, it can be used for various applications such as an intermediate layer and a skin layer constituting packing.

  Among them, the porous body of the present invention can be particularly suitably used as a polishing pad, can improve the polishing life and the polishing rate, and can reduce the amount of carbon black used for improving the wear properties during polishing. Therefore, scratches during polishing can be reduced.

  The urethane resin composition used in the present invention reacts a polyol (a1), a polyisocyanate (a2) and a chain extender (a3) containing an aromatic polyester polyol (a1-1) in a range of 5 to 80% by mass. The urethane resin (A) and organic solvent (B) obtained in this way are contained.

  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 suitably used.

  Examples of the compound having a hydroxyl group include ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, heptanediol, octanediol, nonanediol, decanediol, trimethylolpropane, trimethylolethane, and glycerin. Can do. 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 acid, trimellitic anhydride, 1,2,5-benzenetricarboxylic acid, 2,5 , 7-naphthalenetricarboxylic acid, pyromellitic acid, pyromellitic anhydride and the like can be used. These aromatic polybasic acids may be used alone or in combination of two or more. Among these, it is preferable to use a phthalic acid compound from the viewpoint of further improving the anti-pore resistance.

  For the purpose of adjusting the viscosity and hardness of the urethane resin composition, other polybasic acids other than the aromatic polybasic acid may be used in combination with the aromatic polybasic acid. Examples of the other polybasic acid 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.

  As content of the said aromatic polybasic acid in the polybasic acid used as a raw material of the said aromatic polyester polyol (a1-1), the point which can further improve the viscosity of a urethane resin composition, hardness, and anti-close-pore property Therefore, it is preferable that it is 20 mass% or more, 30 mass% or more is more preferable, and 40 mass% or more is still more preferable.

  The number average molecular weight of the aromatic polyester polyol (a1-1) is preferably in the range of 500 to 5,000, and in the range of 800 to 4,000, from the viewpoint of mechanical strength and anti-pore resistance. More preferably, the range of 900-3,000 is still more preferable. In addition, the number average molecular weight of the said aromatic polyester polyol (a1-1) shows the value obtained by measuring on condition of the following by gel permeation chromatography (GPC) method.

Measuring device: High-speed GPC device (“HLC-8220GPC” manufactured by Tosoh Corporation)
Column: The following columns manufactured by Tosoh Corporation were connected in series.
"TSKgel G5000" (7.8 mm ID x 30 cm) x 1 "TSKgel G4000" (7.8 mm ID x 30 cm) x 1 "TSKgel G3000" (7.8 mm ID x 30 cm) x 1 “TSKgel G2000” (7.8 mm ID × 30 cm) × 1 detector: RI (differential refractometer)
Column temperature: 40 ° C
Eluent: Tetrahydrofuran (THF)
Flow rate: 1.0 mL / min Injection amount: 100 μL (tetrahydrofuran solution with a sample concentration of 0.4 mass%)
Standard sample: A calibration curve was prepared 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

  As content of the said aromatic polyester polyol (a1-1) in the said polyol (a1), it is essential that it is the range of 5-80 mass%. When the content is within the above range, the soft segment in polyurethane has very good crystallinity and moderate brittleness is obtained, so that a porous body having excellent anti-close resistance can be obtained. When the content is less than 5% by mass, the crystallinity of the soft segment is low, and the desired closed pore resistance cannot be obtained, and when it exceeds 80% by mass, the crystallinity of the soft segment Is too high and the brittleness becomes high, so that the cell is easily closed. The content is preferably in the range of 10 to 70% by mass, and more preferably in the range of 15 to 60% by mass, from the viewpoint that the anti-close resistance can be further improved.

  Examples of the polyol (a1) that can be used in addition to the aromatic polyester polyol (a1-1) include aliphatic polyester polyol, polyether polyol, polycarbonate polyol, polycaprolactone polyol, polyacryl polyol, dimer diol, polybutadiene polyol, and water. An additive polybutadiene polyol or the like can be used. These polyols may be used alone or in combination of two or more. Among these, from the point that the viscosity, hardness and mechanical strength of the urethane resin composition can be further improved while maintaining excellent closed pore resistance, from the group consisting of aliphatic polyester polyol, polyether polyol and polycarbonate polyol It is preferable to use one or more selected polyols.

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

  Examples of the polyether polyol include polyoxyethylene polyol, polyoxypropylene polyol, polyoxytetramethylene polyol, polyoxyethylene polyoxypropylene polyol, polyoxyethylene polyoxytetramethylene polyol, polyoxypropylene polyoxytetramethylene polyol. Etc. can be used. These polyether polyols may be used alone or in combination of two or more.

  As said polycarbonate polyol, what is obtained by making carbonate ester and / or phosgene react with the compound which has a 2 or more hydroxyl group can be used, for example.

  As the carbonate ester, for example, methyl carbonate, dimethyl carbonate, ethyl carbonate, diethyl carbonate, cyclocarbonate, diphenyl carbonate and the like can be used. These carbonates 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, and tripropylene glycol. 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,5-hexanediol, 1,6-hexanediol, 2,5-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 2 -Methyl-1,3-propanediol, neopentylglyce 2-butyl-2-ethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octanediol Aliphatic polyols such as 1,2-cyclobutanediol, 1,3-cyclopentanediol, 1,4-cyclohexanedimethanol, cycloheptanediol, cyclooctanediol, hydroxypropylcyclohexanol, etc .; bisphenol A An aromatic polyol such as bisphenol F or 4,4′-biphenol can be used. These compounds may be used alone or in combination of two or more.

  As the number average molecular weights of the aliphatic polyester polyol, polyether polyol and polycarbonate polyol, the viscosity, hardness and mechanical strength of the urethane resin composition can be further improved while maintaining excellent closed pore resistance. The range is preferably 500 to 5,000, more preferably 800 to 4,000, and still more preferably 900 to 3,000. In addition, the number average molecular weight of the said aliphatic polyester polyol, polyether polyol, and polycarbonate polyol shows the value obtained by measuring similarly to the number average molecular weight of the said 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-2,6-phenylene diisocyanate, and 1-methyl-2. , 5-phenylene diisocyanate, 1-methyl-3,5-phenylene diisocyanate, 1-ethyl-2,4-phenylene diisocyanate, 1-isopropyl-2,4-phenylene diisocyanate, 1,3-dimethyl-2,4-phenylene Diisocyanate, 1,3-dimethyl-4,6-phenylene diisocyanate, 1,4-dimethyl-2,5-phenylene diisocyanate, diethylbenzene diisocyanate, diisopropylbenzene diisocyanate, 1-methyl-3,5-diethylbenzenedii Cyanate, 3-methyl-1,5-diethylbenzene-2,4-diisocyanate, 1,3,5-triethylbenzene-2,4-diisocyanate, naphthalene-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 Aromatics such as -4,4'-diisocyanate, 3-3'-dimethylbiphenyl-4,4'-diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, diphenylmethane-2,4-diisocyanate Po Isocyanate; tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, dodecamethylene diisocyanate, trimethylhexamethylene diisocyanate, 1,3-cyclopentylene diisocyanate, 1,3-cyclohexylene diisocyanate, 1,4-cyclohexylene diisocyanate, 1, 3-di (isocyanatemethyl) cyclohexane, 1,4-di (isocyanatemethyl) cyclohexane, lysine diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 2,4'-dicyclohexylmethane diisocyanate, 2,2'-dicyclohexyl Fats such as methane diisocyanate, 3,3′-dimethyl-4,4′-dicyclohexylmethane diisocyanate An aliphatic or alicyclic polyisocyanate can be used. These polyisocyanates may be used alone or in combination of two or more. Among these, aromatic polyisocyanate is preferably used, and 4,4′-diphenylmethane diisocyanate is more preferable from the viewpoint of further improving the anti-pore resistance and flexibility.

  As said chain extender (a3), the chain extender which has a hydroxyl group, the chain extender which has an amino group, etc. can be used, for example. These chain extenders may be used alone or in combination of two or more.

  Examples of the chain extender having a hydroxyl group include ethylene glycol, diethylene recall, 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. 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.

  As the chain extender (a3), it is preferable to use a chain extender having a hydroxyl group, and an aliphatic polyol compound is more preferable from the viewpoint of suppressing discoloration over time and further improving flexibility.

  The amount of the chain extender (a3) used is preferably in the range of 0.5 to 30 parts by mass with respect to 100 parts by mass of the polyol (a1) from the viewpoint of resistance to closed pores and flexibility. The range of 1-20 mass parts is more preferable.

  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 charged and reacted. These reactions may be performed at a temperature of 50 to 100 ° C. for 3 to 10 hours, for example. Moreover, you may perform the said reaction in the organic solvent (B) mentioned later.

  The molar ratio of the total hydroxyl group and / or amino group of the polyol (a1) and the chain extender (a3) to the isocyanate group of the polyisocyanate (a2) [(isocyanate group) / (hydroxyl group). And / or 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.

  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, from the viewpoint of further improving the anti-pore resistance and flexibility. The range of 000 to 300,000 is more preferable, and the range of 30,000 to 150,000 is still more preferable. In addition, the weight average molecular weight of the said urethane resin (A) shows the value obtained by measuring similarly to the number average molecular weight of the said aromatic polyester polyol (a1-1).

  The content of the aromatic ring in the urethane resin (A) is in the range of 100 to 2,700 mmol / kg from the point that the pore resistance, the viscosity, the hardness and the mechanical strength of the urethane resin composition can be further improved. The range of 200 to 2,400 mol / kg is more preferable, and the range of 400 to 2,000 mmol / kg is still more preferable. In addition, content of the said aromatic ring shows content of the aromatic ring with respect to the total mass of each raw material which comprises the said urethane resin (A).

  Examples of the organic solvent (B) include ketones such as N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, methyl ethyl ketone, methyl-n-propyl ketone, acetone, and methyl isobutyl ketone. Solvent: Ester solvent such as methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, isopropyl acetate, isobutyl acetate, isobutyl acetate, sec-butyl acetate, etc .; use alcohol solvents such as methanol, ethanol, isopropyl alcohol, butanol, etc. Can do. These organic solvents may be used alone or in combination of two or more.

  Among these, it is preferable to use N, N-dimethylformamide because it is highly soluble in the urethane resin (A) and water and can be easily removed by drying with hot air. The content when N, N-dimethylformamide is used is preferably 70% by mass or more in the organic solvent (B).

  As content of the said organic solvent (B), it is preferable that it is the range of 30-90 mass% in a urethane resin composition from the point of workability | operativity at the time of handling a urethane resin composition, and a viscosity, 40-80 mass % Range is more preferred.

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

  Examples of the other additives include pigments, flame retardants, plasticizers, softeners, stabilizers, waxes, antifoaming agents, dispersants, penetrants, surfactants, fillers, antifungal agents, antibacterial agents, and ultraviolet rays. Absorbers, antioxidants, weathering stabilizers, fluorescent brighteners, anti-aging agents, thickeners and the like can be used. 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.

  The wet film-forming method means that the urethane resin composition is applied or impregnated on the surface of a substrate, and then the urethane resin (A) is solidified by bringing water or water vapor or the like into contact with the coated surface or impregnated surface. And producing a porous body.

  As a base material which apply | coats the said urethane resin composition, the base material which consists of a nonwoven fabric, a woven fabric, and a knitted fabric; Resin film etc. can be used, for example. Examples of constituents of the substrate include 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.

  The surface of the base material may be subjected to treatments such as antistatic treatment, mold release treatment, water repellent treatment, water absorption treatment, antibacterial and deodorizing treatment, antibacterial treatment, and ultraviolet blocking treatment as necessary.

  Examples of the method for 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, in order to adjust the viscosity of the urethane resin composition and improve the coating workability, the amount of the organic solvent (B) used may be adjusted as necessary.

  As a film thickness of the coating film which consists of the said urethane resin composition apply | coated or impregnated by the said method, it is the range of 0.5-5 mm, for example, and the range of 0.5-3 mm is preferable.

  Examples of a method for bringing water or water vapor into contact with a coated surface formed by applying or impregnating the urethane resin composition include, for example, immersing a substrate provided with a coating layer or impregnated layer made of the urethane resin composition in a water bath A method of spraying water on the coated surface using a spray or the like. For example, the immersion may be performed 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 at the surface with normal temperature water or warm water to extract and remove the organic solvent (C), and then dried. The washing is preferably performed with water at 5 to 60 ° C. for 20 to 120 minutes, and the water used for washing is preferably replaced one or more times or continuously with running water. The drying is preferably performed for 10 to 60 minutes using a dryer or the like adjusted to 80 to 120 ° C.

  The porous body obtained by the above method has a spindle-shaped or teardrop-shaped porous structure that is long in the thickness direction of the surface. The size of the hole can be appropriately adjusted according to the application, but from the point that the closed hole resistance, flexibility and durability can be further improved, the portion having the largest width in the surface direction (thickness direction) has a diameter of 1 to 1. A range of 10 μm is preferable. Since the porous body obtained in the present invention has pores that are long in the thickness direction and uniform in diameter in the surface direction, it is flexible and has an appropriate elasticity against compression in the thickness direction. It can be suitably used as a pad. The thickness of the porous body is preferably 0.45 to 1 mm when used in applications such as a polishing pad, and more preferably 0.45 to 0.7 mm. .

  As described above, the porous body of the present invention has excellent durability and wear resistance because the cells are less likely to be closed during dressing and polishing. Moreover, since the porous body of the present invention also has flexibility, the skin layer and intermediate layer of leather-like sheets such as synthetic leather and artificial leather used for clothing, vehicle seats, furniture sheets, shoes, bags, etc .; polishing pad ; Back pad for polishing; Medical hygiene materials such as surgical clothing and bed sheets; Sheets for building materials such as windproof and waterproof sheets and anti-condensation sheets; Packaging materials such as desiccants, dehumidifiers and fragrances; In addition, it can be used for various applications such as an intermediate layer and a skin layer constituting packing.

  Among them, the porous body of the present invention can be particularly suitably used as a polishing pad obtained by dressing, improves the polishing life and the polishing rate, and also improves the wearability during polishing. Since the amount added can be reduced, scratching during polishing can be reduced.

  Hereinafter, the present invention will be described in more detail with reference to examples.

[Example 1]
To a reaction apparatus having a stirrer, a condenser reflux, and a thermometer, an aromatic polyester polyol (reacted ethylene glycol and phthalic acid, number average molecular weight 2,000, hereinafter abbreviated as “aromatic PEs-1”). .) 20 parts by mass, aliphatic polyester polyol (reaction of ethylene glycol and adipic acid, number average molecular weight 2,000, hereinafter abbreviated as “aliphatic PEs-1”) 80 parts by mass, ethylene 8 parts by weight of glycol (hereinafter abbreviated as “EG”), 357 parts by weight of N, N-dimethylformamide (hereinafter abbreviated as “DMF”), and 4,4′-diphenylmethane diisocyanate (hereinafter referred to as “DMF”) , Abbreviated as “MDI”), and allowed to react at 60 ° C. for 6 hours with stirring, followed by isopropyl alcohol (hereinafter “IP A "). The urethane resin composition had a solid content of 30% by mass and a viscosity of 800 dPa · s, and the urethane resin had a weight average molecular weight of 80,500 and an aromatic ring content of 660 mmol / kg.

  To 100 parts by mass of the obtained urethane resin composition, 40 parts by mass of DMF and 1 part by mass of surfactant “Asistar SD-7” for wet processing manufactured by DIC Corporation were added to prepare a compounded liquid. After coating on a tarate (PET) film to a thickness of 1 mm, it was immersed in water at 25 ° C. for 10 minutes to solidify. Then, the porous body was obtained by washing in warm water of 50 ° C. for 60 minutes and leaving it in a 100 ° C. dryer for 30 minutes.

[Example 2]
Except having changed the usage-amount of the said aromatic PEs-1 from 20 mass parts to 50 mass parts, and having changed the usage-amount of the said aliphatic PEs-1 from 80 mass parts to 50 mass parts, it carried out similarly to Example 1. A urethane resin composition and a porous body were obtained. The urethane resin composition had a solid content of 30% by mass and a viscosity of 950 dPa · s, and 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 material 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 used 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 · s, and the weight average molecular weight of the urethane resin was 82,000.

[Comparative Example 2]
Except having changed the usage-amount of the said aromatic PEs-1 from 20 mass parts to 85 mass parts, and having changed the usage-amount of the said aliphatic PEs-1 from 80 mass parts to 15 mass parts, it is the same as that of Example 1. A urethane resin composition and a porous body were obtained. The urethane resin composition had a solid content of 30% by mass and a viscosity of 1010 dPa · s, the weight average molecular weight of the urethane resin was 89,000, and the content of the aromatic ring was 2,820 mmol / kg.

[Evaluation method for closed hole resistance]
The following Taber abrasion test was performed on the porous bodies obtained in Examples and Comparative Examples.
Tester: Taber abrasion tester "Rotary abrasion tester" manufactured by Toyo Seiki Seisakusho Co., Ltd.
Wear wheel; CS-10
Load: 250g of wear arm
Number of revolutions: 70 revolutions / minute Number of tests: 3,000 times

  The surface of the porous body after the Taber abrasion test was observed using a scanning electron microscope “SU3500” (500 times magnification) manufactured by Hitachi High-Technology Corporation. The case where the closed portion could not be confirmed on the surface of the porous body was evaluated as “T”, and the confirmed portion was evaluated as “F”.

  It turned out that Example 1 and 2 which is a porous body of this invention has the outstanding closed | mouth resistance.

  On the other hand, Comparative Examples 1 and 2 are embodiments in which the amount of the aromatic polyester polyol (a1-1) used exceeds the range defined in the present invention, but both have poor anti-closeability.

Claims (2)

Aromatic polyester polyol (a1-1) containing a range of 5 to 80 mass%, further polyols containing aliphatic polyester polyol Lumpur (a1), the polyisocyanate (a2) and a chain extender and (a3) reaction Polishing characterized in that it is obtained by dressing a porous body obtained by processing a urethane resin composition containing a urethane resin (A) and an organic solvent (B) obtained by a wet film-forming method. A method for manufacturing a pad. The method for producing a polishing pad according to claim 1, wherein the aromatic polyester polyol (a1-1) is a reaction product of a compound having a hydroxyl group and a polybasic acid containing a phthalic acid compound.