JP2019116616A - Polishing pad and urethane resin composition for polishing pad - Google Patents

Abstract

To provide a polishing pad having a high polishing rate and enabling a polished article excellent in high flatness (little in edge sagging) to be obtained.SOLUTION: The polishing pad is a cured product of a urethane resin composition comprising a main agent (i) containing a urethane prepolymer (A), and a curing agent (ii). The urethane prepolymer (A) is a reaction product of a composition comprising a polyol constituent (a) containing polyol (a1) having a molecular weight of 300 or more, and short-chain glycol (a2) having a molecular weight of less than 300, and polyisocyanate (b), and has an isocyanate group at a terminal thereof, wherein the polyol constituent (a) contains 40 mass% or more and 90 mass% or less of polytetramethylene glycol, and 1 mass% or more of short-chain glycol (a2). The cured product has a peak value of tan δ within the range of 120°C or higher to 200°C or lower, wherein the peak value of tan δ is within the range of 120°C or higher to 200°C or lower is 0.18 or greater.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a polishing pad and a urethane resin composition for a polishing pad.

  The present invention particularly relates to a polishing pad that can be suitably used for polishing an optical lens, a glass substrate, a silicon wafer, a semiconductor device, etc., and a method of manufacturing the polishing pad and a polishing method.

  Optical lenses, glass substrates for liquid crystal displays (LCDs), glass substrates for hard disks (HDDs), silicon wafers, semiconductor devices, etc. are required to have high polishing efficiency and non-scratch properties.

  In particular, in the semiconductor device, as the degree of integration of the semiconductor circuit rapidly increases, miniaturization and multilayer wiring for the purpose of high density progress, and higher surface flatness of the processed surface and higher polishing efficiency are required. It is done. Moreover, also in the said glass substrate for liquid crystal displays, with the enlargement of a liquid crystal display, the higher surface flatness of a process surface and high polishing efficiency are calculated | required. As described above, the requirement for surface flatness of the processed surface is advanced, and further, the required performance such as the polishing efficiency in the polishing process is further increased.

  Therefore, chemical mechanical polishing, so-called CMP (Chemical Mechanical Polishing), is widely adopted as a polishing method capable of forming a surface having excellent flatness in the manufacturing process of optical lenses, semiconductor devices and LCDs. ing.

In the above-mentioned CMP method, a free abrasive method is generally adopted in which polishing is performed by supplying a slurry (polishing liquid) in which abrasive particles (abrasive particles) are dispersed in an alkali solution or an acid solution at the time of polishing. That is, (the processing surface of) the object to be polished is planarized by the mechanical action by the abrasive grains in the slurry and the chemical action by the alkaline solution or the acid solution. Here, the polishing performance such as the polishing accuracy and the polishing efficiency required for the CMP method is required as the flatness of the processing surface is advanced, and specifically, the high polishing rate, the non-scratching property, and the high flatness are required. Is rising. As a polishing pad using the loose abrasive method of the above-mentioned CMP method, for example, a polishing pad having a high polishing rate which hardly generates a scratch is proposed by controlling specific parameters such as hardness, wear, relaxation time and elastic modulus. (See Patent Documents 1 and 2).
Further, for example, a urethane polishing pad having a specific composition such as ethylene glycol monophenyl ether is said to be excellent in dressing properties (cut rate) (see Patent Document 3). Further, for example, a urethane polishing pad having a macrophase separation structure formed by utilizing the compatibility between the polyester-based polyol and the polyether-based polyol used as raw materials is said to have a large polishing rate and excellent stability (patent document See 4, 5).
Further, for example, a polishing pad in which a raw material composition is specified to a specific cell diameter or storage elastic modulus is considered to have a high polishing rate and an excellent break-in time (see Patent Document 6).

  As described above, the industry strongly demands a polishing pad that satisfies the advanced high polishing rate, low scratch property, and high flatness required for high precision polishing, and various attempts are made. Although it is, it is the fact that it has not been found yet.

JP, 2014-111296, A Patent No. 5710353 Patent 5738731 Public Relations Patent 5623927 gazette Patent 5623927 Public Relations Patent No. 5353434 Public Relations

  The problem to be solved by the present invention is to provide a polishing pad which has a high polishing rate and is capable of obtaining an object to be polished excellent in high flatness (with less edging).

  As a result of intensive studies to solve the above problems, the present inventors set the composition of the soft segment and the ratio of the hard segment to a specific range, and in the dynamic viscoelasticity measurement, a specific value or more in a specific temperature range It has been found that it is possible to provide a polishing pad having a high polishing rate and having a high flatness (with less edge) by providing a tan δ peak of The present invention has been completed.

  That is, the polishing pad of the present invention is a cured product of a urethane resin composition containing a main agent (i) containing a urethane prepolymer (A) and a curing agent (ii), and the urethane prepolymer (A) is A reactant comprising a polyol component (a) containing a polyol (a1) having a molecular weight of 300 or more and a short chain glycol (a2) having a molecular weight of less than 300 and a polyisocyanate (b) as at least a part of the raw material The polyol component (a) contains polytetramethylene glycol at a content of 40% by mass or more and 90% by mass or less, and the content of the short chain glycol (a2) is 1% by mass or more in the polyol component (a), and the cured product has a measurement frequency of 1 Hz in a dynamic viscoelasticity measurement at 120 ° C. or higher 00 ° C. are those having a peak of tanδ within the scope of the following, and the peak value of tanδ in the range of the 120 ° C. or higher 200 ° C. or less is 0.18 or more.

  The polishing pad of the present invention is capable of a polishing pad having a high polishing rate and capable of obtaining an object to be polished excellent in high flatness (with less edging).

FIG. 1 is a scanning electron microscope (SEM) image of a cross section (sliced surface) of the polishing pad of Example 1. FIG. 2 is a scanning electron microscope (SEM) image of a cross section (slice surface) of the polishing pad of Comparative Example 1. FIG. 3 is a dynamic viscoelasticity measurement chart of the polishing pad of Example 3. FIG. 4 is a distribution diagram of heights obtained by measuring the surface of a silicon wafer polished by the polishing pad of Example 3 with a spectral interference laser displacement meter. FIG. 5 is a dynamic viscoelasticity measurement chart of the polishing pad of Comparative Example 7. FIG. 6 is a distribution diagram of heights obtained by measuring the surface of a silicon wafer polished by the polishing pad of Comparative Example 7 with a spectral interference laser displacement meter.

  The polishing pad of the present invention is a cured product of a urethane resin composition containing a main agent (i) containing a urethane prepolymer (A) and a curing agent (ii), and the cured product has a measurement frequency of 1 Hz. In the dynamic viscoelasticity measurement, it has a tan δ peak in the range of 120 ° C. or more and 200 ° C. or less, and the peak value of tan δ in the range of 120 ° C. or more and 200 ° C. or less is 0.18 or more. The presence of a peak having the above in the dynamic viscoelasticity measurement suggests that a fine domain having a specific viscoelasticity is present in the cured product, and in the present invention, the presence of this fine domain It is considered that high polishing rate and high flatness of the object to be polished can be achieved. In the present invention, the fine domains can be generated by specifying the composition of the polyol (a).

  In the dynamic viscoelasticity measurement in which the measurement frequency is 1 Hz, the peak of tan δ is preferably in the range of 120 ° C. or more and 180 ° C. or less, and more preferably in the range of 110 ° C. or more and 170 ° C. or less.

  The peak value of the above-mentioned taδ is preferably 0.20 or more, more preferably 0.25 or more, still more preferably 0.3 or more, and the upper limit is not particularly limited. It may be.

  In the main agent (i), the urethane prepolymer (A) is a reaction product of a polyol component (a) and a polyisocyanate (b) (a polyol component (a) and a polyisocyanate (b) at least partially) (Reactant) which has an isocyanate group at the end.

  The polyol component (a) may contain one or more polyols, and at least a polyol (a1) having a molecular weight of 300 or more (hereinafter sometimes simply referred to as "polyol (a1)") and It contains short chain glycol (a2) having a molecular weight of less than 300 (hereinafter sometimes simply referred to as "short chain glycol").

The polyol (a1) can form a soft segment in the resulting polishing pad. The number average molecular weight of the polyol (a1) is preferably 700 or more, more preferably 1,100 or more, still more preferably 1,400 or more, preferably 8,000 or less, more preferably 5,000 or less, and further Preferably it is 3,000 or less, especially preferably 2,500 or less.
In the present specification, the number average molecular weight can be measured by gel permeation chromatography (GPC method) using polystyrene as a standard sample. Moreover, when 2 or more types of polyols are contained as said polyol (a1), the number average molecular weight of the said polyol (a1) can be calculated as a weighted average value based on the number average molecular weight and mass ratio of each polyol .

  The number of hydroxyl groups contained in the polyol is 2 or more, preferably 5 or less.

  The polyol (a1) contains a polyether polyol (a1-1). Examples of the polyether polyols (a1-1) include polyoxyalkylene polyols obtained by ring-opening polymerization of cyclic ethers, and one or two of compounds having two or more groups having active hydrogen atoms as initiators It may be obtained by using the above.

  The carbon atom number of the cyclic ether is preferably 2 to 10, more preferably 2 to 6, and still more preferably 2 to 4. The hydrogen atom contained in the cyclic ether may be substituted by a halogen atom. As the cyclic ether, one or more species can be used. For example, ethylene oxide, propylene oxide, 1,2-butylene oxide, 2,3-butylene oxide, styrene oxide, epichlorohydrin, tetrahydrofuran, alkyl And the like.

  As the initiator, one or more kinds can be used. For example, ethylene glycol, diethylene glycol, propylene glycol, trimethylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6- Compounds having two active hydrogen atoms such as hexanediol, neopentyl glycol and water; glycerin, diglycerin, trimethylolethane, trimethylolpropane, hexanetriol, monoethanolamine, diethanolamine, triethanolamine, ethylenediamine, pentaerythritol, The compound etc. which have 3 or more of active hydrogen atoms, such as a sugar, are mentioned.

  The polyether polyol (a1-1) contains at least polytetramethylene glycol. The number average molecular weight of polytetramethylene glycol contained in the polyol component (a1) is 300 or more, preferably 1,100 or more, more preferably 1,300 or more, preferably 4,000 or less, more preferably Is 3,000 or less, more preferably 2,500 or less. When two or more kinds of polytetramethylene glycols having different number average molecular weights are contained, the number average molecular weight of polytetramethylene glycol may be calculated as a weighted average value based on the number average molecular weight and mass ratio of each polytetramethylene glycol. it can.

In the polyol component (a), the content of polytetramethylene glycol is 40% by mass or more, preferably 50% by mass or more, more preferably 60% by mass or more, and 90% by mass or less, preferably 85% by mass or less And more preferably 80% by mass or less.
The content of polytetramethylene glycol in the polyol (a1) is preferably more than 50% by mass, more preferably 60% by mass or more, more preferably 70% by mass or more, and still more preferably 75% by mass or more. It is less than mass%. Particularly preferably, the polyol (a1) is polytetramethylene glycol.

  The polyether polyol (a1-1) may contain a polyoxypropylene polyol. The number average molecular weight of the polyoxypropylene polyol is 300 or more, preferably 400 or more, preferably 5,000 or less, more preferably 2,000 or less, and still more preferably 1,000 or less. When two or more kinds of polyoxypropylene polyols having different number average molecular weights are contained, the number average molecular weight of the polyoxypropylene polyol may be calculated as a weighted average value based on the number average molecular weight and mass ratio of each polyoxypropylene polyol. it can.

  The number of hydroxyl groups contained in the polyoxypropylene polyol is 2 or more, preferably 3 or more, preferably 5 or less, more preferably 4 or less.

  When the polyoxypropylene polyol is contained, the content of the polyoxypropylene polyol in the polyol (a1) is preferably 5 parts by mass or more, more preferably 10 parts by mass or more with respect to 100 parts by mass of polytetramethylene glycol. Preferably it is 50 mass parts or less, More preferably, it is 40 mass parts or less, More preferably, it is 30 mass parts or less.

  The content of the polyether polyol (a1-1) in the polyol (a1) is preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, and the upper limit is 100%. %.

  The polyol (a1) may contain another polyol (a1-2) in addition to the polyether polyol (a1-1). As said other polyol (a1-2), 1 type (s) or 2 or more types can be used, For example, a polyester polyol, a polycarbonate polyol, a polybutadiene polyol, a polyacryl polyol, a polybutadiene polyol, a polyisoprene polyol etc. are mentioned.

  As the polyester polyol, one type or two or more types can be used. For example, a polyester polyol obtained by reacting a low molecular weight polyol and a polycarboxylic acid; ring-opening cyclic ester compounds such as ε-caprolactone Examples include polyester polyols obtained by polymerization reaction; polyester polyols obtained by copolymerizing these.

  As said low molecular weight polyol, 1 type, or 2 or more types can be used, For example, the polyol whose molecular weight is 50 or more and less than 300 is mentioned, For example, ethylene glycol, propylene glycol, 1, 4- butanediol, 1, Aliphatic polyols such as 6-hexanediol, diethylene glycol, neopentyl glycol and 1,3-butanediol; polyols having an alicyclic structure such as cyclohexanedimethanol; polyols having an aromatic ring such as bisphenol A and bisphenol F It can be mentioned. Among these, 1,6-hexanediol and neopentyl glycol are preferable.

  As said polycarboxylic acid which can be used for manufacture of said polyester polyol, 1 type (s) or 2 or more types can be used, For example, aliphatic polycarboxylic acids, such as a succinic acid, adipic acid, sebacic acid, dodecane dicarboxylic acid; Aromatic polycarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid and naphthalenedicarboxylic acid; their anhydrides or esters and the like.

  The polycarbonate polyol is obtained by subjecting a carbonic acid and a carbonic ester to an esterification reaction with a polyhydric alcohol. As the polyhydric alcohol, one or more species can be used. For example, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, polyethylene glycol, polyoxypropylene And glycol, polytetramethylene glycol and the like.

Examples of the polybutadiene polyol include polyols obtained by adding an alkylene oxide (for example, ethylene oxide, propylene oxide, etc.) to polybutadiene.
Examples of polyacrylic polyols include polyols obtained by copolymerizing an acrylic ester and a vinyl compound.

Examples of polyisoprene polyols include polyols obtained by adding an alkylene oxide (for example, ethylene oxide, propylene oxide, etc.) to polyisoprene.

  In the polyol component (a), the content of the polyol (a1) is preferably 60% by mass or more, more preferably 70% by mass or more, preferably less than 100% by mass, more preferably 99% by mass or less .

  The short chain glycol (a2) can form a hard segment in the obtained polishing pad. As the short chain glycol (a2), one or more of glycols having a molecular weight of less than 300 can be used. For example, ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol , 2-methyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol (2,2-dimethyl ester 1,3-propanediol), 2-isopropyl-1,4-butanediol, 3-methyl-2,4-pentanediol, 2,4-pentanediol, 1,5-pentanediol, 3-methyl-1 5-Pentanediol, 2-Methyl-2,4-Pentanediol, 2,4-Dimethyl-1,5-Pentanedio 2,4-diethyl-1,5-pentanediol, 1,5-hexanediol, 1,6-hexanediol, 2-ethyl-1,3-hexanediol, 2-ethyl-1,6-hexanediol, Aliphatic diols such as 1,7-heptanediol, 3,5-heptanediol, 1,8-octanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol and 1,10-decanediol Cycloaliphatic such as cyclohexanedimethanol (eg, 1,4-cyclohexanedimethanol), cyclohexanediol (eg, 1,3-cyclohexanediol, 1,4-cyclohexanediol), 2-bis (4-hydroxycyclohexyl) -propane, etc. Diol etc. are mentioned.

  Among them, the short chain glycol (a2) is preferably an aliphatic diol, and particularly preferably diethylene glycol.

  The content of the short chain glycol (a2) in the polyol component (a) is 1% by mass or more, preferably 5% by mass or more, more preferably 10% by mass or more, and still more preferably 15% by mass or more Preferably it is 50 mass% or less, More preferably, it is 40 mass% or less, More preferably, it is 30 mass% or less.

  The content of the polyol (a1) and the short chain glycol (a2) in the polyol component (a) is preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably 95% by mass or more. The upper limit is 100% by mass.

  The polyol component (a) may contain another polyol (a3) in addition to the polyol (a1) and the short chain glycol (a2). Examples of the other polyol (a3) include trimethylolethane, trimethylolpropane, hexitols, pentitols, glycerin, polyglycerin, pentaerythritol, dipentaerythritol, tetramethylolpropane and the like having a molecular weight of less than 300; And polyols having three or more.

  As said polyisocyanate (b), 1 type or 2 types or more can be used, For example, polyisocyanate which has alicyclic structures, such as cyclohexane diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate; 4,4'- diphenylmethane diisocyanate Aromatic polyisocyanates such as 2,4'-diphenylmethane diisocyanate, carbodiimide modified diphenylmethane diisocyanate, crude diphenylmethane diisocyanate, phenylene diisocyanate, tolylene diisocyanate, naphthalene diisocyanate; hexamethylene diisocyanate, lysine diisocyanate, xylylene diisocyanate, tetramethyl xylylene diisocyanate Aliphatic polyisocyanates such as It is below. Among these, aromatic polyisocyanates are preferable, toluene diisocyanate or diphenylmethane diisocyanate is preferable, and toluene diisocyanate is particularly preferable, because high hardness of the polishing pad and polishing rate can be further improved.

  The equivalent ratio (NCO / OH) of the isocyanate group contained in the polyisocyanate (b) to the hydroxyl group contained in the polyol component (a) is preferably 1.3 or more, more preferably 1.5 or more, Preferably it is 6.5 or less, more preferably 4 or less, and particularly preferably 3 or less. As the molar ratio (NCO / OH) is larger, the viscosity of the urethane prepolymer (A) can be lowered, and in the production of the polishing pad, the flow rate can be stabilized to improve the mixing property and the quality can be easily improved. Further, as the molar ratio (NCO / OH) is smaller, the viscosity of the urethane prepolymer (A) can be increased, and the pot life can be lengthened.

  The urethane prepolymer (A) is a reaction product (urethane reaction product) of the polyol component (a) and the polyisocyanate (b). The reaction order of the polyol (a1), the short chain glycol (a2) and the other polyol (a3) used as needed and the polyisocyanate (b) is not particularly limited, and the polyol (a1), the short chain The glycol (a2) and the other polyol (a3) optionally used may be simultaneously reacted with the polyisocyanate (b), and the polyol (a1) is reacted with the polyisocyanate (b) After that, the obtained reactant may be reacted with the short chain glycol (a2) and the other polyol (a3) optionally used.

  The isocyanate group equivalent of the urethane prepolymer (A) is preferably 200 g / eq. Or more, more preferably 250 g / eq. Or more, preferably 800 g / eq. Or less, more preferably 600 g / eq. It is below.

  The isocyanate group equivalent (NCO equivalent) of the urethane prepolymer (A) dissolves the sample in dry toluene in accordance with the method prescribed in JIS-K-7301: 2003, and the excess di-n-butylamine solution In addition, the reaction is carried out, and the value obtained by back titration of the remaining di-n-butylamine with a hydrochloric acid standard solution is shown.

The viscosity (80 ° C.) of the urethane prepolymer (A) is preferably 2,000 mPa · s or less, more preferably 1,500 mPa · s or less, still more preferably 1,200 mPa · s or less, for example, 300 mPa · s. The above may be 400 mPa · s or more.
The viscosity (80 ° C.) of the urethane prepolymer (A) can be measured using a B-type viscometer at a temperature of 80 ° C.

  The main agent (i) may contain another urethane prepolymer other than the urethane prepolymer (A). The content of the urethane urethane prepolymer (A) is preferably 70% by mass or more, more preferably 80% by mass or more, and still more preferably 90% by mass in the total of the urethane prepolymer (A) and the other urethane prepolymers. It is the above and an upper limit is 100 mass%.

  The main agent (i) may further contain a polyisocyanate. As the polyisocyanate, the polyisocyanate exemplified as the polyisocyanate (b) can be used, and aromatic polyisocyanates such as 4,4'-diphenylmethane diisocyanate and tolylene diisocyanate; fats such as dicyclohexylmethane diisocyanate and isophorone diisocyanate Particularly preferred are polyisocyanates having a cyclic structure.

  The curing agent (ii) contains a compound having a group ([NH] group and / or [OH] group) containing an active hydrogen atom that reacts with the isocyanate group of the main agent (i). As the compound having a group containing an active hydrogen atom, one or more kinds can be used. For example, aliphatic or alicyclic amine compounds such as ethylene diamine, propane diamine, hexane diamine, isophorone diamine; phenylene Aromatic amine compounds such as diamine, 3,3'-dichloro-4,4'-diaminodiphenylmethane, polyaminochlorophenylmethane compounds; ethylene glycol, diethylene glycol, propanediol, butanediol, hexanediol, neopentyl glycol, 3-methyl- 1,5-Pentanediol, bisphenol A, alkylene oxide adduct of bisphenol A, polyether polyol, polyester polyol, polycaprolactone polyol, polycarbonate polyol, etc. Compounds having more than five hydroxyl groups; multimers of the aromatic amine compound (preferably 2-4 mers); and the like and mixtures thereof.

  The mixture is preferably a mixture containing a multimer of the aromatic amine compound, and the content of the multimer in the mixture is preferably 10% by mass or more, more preferably 20% by mass or more, and preferably Is 80% by mass or less, more preferably 70% by mass or less.

  The mixture may further contain a polyol (preferably a polyether polyol). The polyol which may be contained in the mixture is preferably a polyether polyol (particularly polyoxytetramethylene glycol), and the number average molecular weight of the polyol is preferably 300 or more, preferably 3,000 or less, more preferably It is 2,000 or less, more preferably 1,500 or less.

  The urethane resin composition may further contain an auxiliary (iii).

  The auxiliary agent (iii) contained in the urethane resin composition preferably contains a polyol, and the polyol may be the same as or different from the polyol (a1) forming the urethane prepolymer (a). Good. As the polyol, one kind or two or more kinds can be used, and examples thereof include a polyoxyalkylene polyol obtained by ring-opening polymerization of the cyclic monoether, and a group having the above-mentioned active hydrogen atom as an initiator It may be one obtained by using one or two or more compounds having one or more.

  The content of the polyol is preferably 50% by mass or more, more preferably 70% by mass or more, and still more preferably 80% by mass or more in the auxiliary agent (iii), and the upper limit is 100% by mass.

  The auxiliary agent (iii) may further contain at least one selected from the group consisting of water, a catalyst described later, and a foam-forming agent described later.

  When auxiliary agent (iii) is contained in the urethane resin composition, the content of auxiliary agent (iii) is, for example, 0.1 parts by mass or more, and further 1 part by mass or more with respect to 100 parts by mass of the urethane prepolymer. Or less, preferably 10 parts by mass or less, more preferably 5 parts by mass or less.

  Since a polishing pad having a high polishing rate after polishing and an object to be polished excellent in high flatness (with less edge deviation) can be obtained, the curing agent (ii) and the need to be described later can be obtained. Ratio of the total number of moles of the group capable of reacting with the isocyanate group contained in the auxiliary agent (iii) to the number of moles of the isocyanate group of the main agent (i) ([the curing agent (ii) and optionally used The total number of moles of groups reacting with the isocyanate group of the auxiliary agent (iii) / [the number of moles of isocyanate group of the urethane prepolymer (A)] (hereinafter referred to as “R value”) is preferably 0.7 to 1.1, more preferably 0.8-1.

  The amount of the curing agent (ii) is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, preferably 50 parts by mass or less, more preferably 30 parts by mass with respect to 100 parts by mass of the main agent (i). It is below a mass part.

  The urethane resin composition used in the present invention contains as a main component the main component (i) containing the urethane prepolymer (A) and a curing agent (ii) containing a compound capable of reacting with isocyanate, and others An additive may also be included. The above-mentioned other additives may be contained in any of the main agent (i), the curing agent (ii) and the auxiliary agent (iii) optionally used, and the reaction with the main agent (i) or the curing agent (ii) If it does not evaporate, it may be contained in main agent (i) or curing agent (i), but additives that react or evaporate are contained in auxiliary agent (iii) used as needed. Is preferred.

  As the above-mentioned other additives, 1 type or 2 types or more can be used, for example, water (reactive foaming agent), a chemical foaming agent, a physical foaming agent, a catalyst, a foam regulating agent, an abrasive, a filler, a pigment And thickeners, antioxidants, UV absorbers, surfactants, flame retardants, plasticizers and the like.

Among them, in the case of obtaining a polishing pad by a water foaming method using the above-mentioned urethane resin composition, it is preferable to use water of a reactive foaming agent. When the foaming agent is water, the content of water is preferably 0.01 parts by mass or more and 1 part by mass or less with respect to 100 parts by mass of the main agent (i).
As blowing agents other than water, chemical blowing agents and physical blowing agents can also be used. Chemical blowing agents include organic ADCA (azodicarbonamide), DPT (N, N'-dinitropentamethylenetetramine), OBSH (4,4'-oxybisbenzenesulfonyl hydrazide), and inorganic hydrogen carbonates. , Carbonates, combinations of bicarbonates and organic acid salts, and the like. Examples of physical blowing agents include hydrocarbon-based cyclopentane and normal pentane, fluorocarbon-based HFC-245fa, HFC-365mfc, HCFO-1233zd, HFO-1336mzz, and the like. The amount of foaming agent may be adjusted appropriately to achieve the target polishing pad density.

  As the catalyst, one or more species can be used. For example, N, N-dimethylaminoethyl ether, triethylenediamine, dimethylethanolamine, triethanolamine, N, N, N ′, N′-tetra Tertiary amine catalysts such as methyl hexamethylene diamine and N-methyl imidazole; and metal catalysts such as dioctyltin dilaurate. Among these, tertiary amines are preferred because they can form stable foams, and N, N-dimethylaminoethyl ether is more preferred.

  When using the said catalyst, since content of the said catalyst can form stable foaming, it is preferable that they are 0.001 mass part or more and 5 mass parts or less with respect to 100 mass parts of said main ingredient (i).

  Examples of the foam stabilizer include silicone foam stabilizers, and one or two or more can be used. For example, “Toray Silicone SH-193”, “Toray Silicone SH-192”, “Toray Silicone SH-190” and the like manufactured by Toray Dow Corning Co., Ltd. may be mentioned.

  When the foam stabilizer is used, the content of the foam stabilizer can stably form fine air bubbles, so that it is 0.001 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the main agent (i) Is preferred.

  As a method of manufacturing a polishing pad using the said urethane resin composition, the said main ingredient (i), the said hardening | curing agent (ii), and the adjuvant (iii) used as needed are mixed, for example, gold | metal | money It is poured into a mold, foamed and cured to obtain a foamed molded product, and then the foamed molded product is removed from the mold and sliced into a sheet and manufactured.

  In many cases with the aid (iii), the curing agent (ii) is with MBOCA (3,3'-dichloro-4,4'-diaminomethane) and in the case of water foaming. The addition destination of water as a reactive blowing agent in the case of water foaming can not be added to the main agent (i) because the main agent (i) and water react with each other. Moreover, the addition to the dissolved MBOCA can not be added because it evaporates at 100 ° C. or higher. Therefore, the addition destination of water is preferably auxiliary (iii).

  When the urethane resin composition contains the auxiliary agent (iii), the content of the auxiliary agent (iii) is, for example, 0.1 parts by mass or more, further 1 part by mass with respect to 100 parts by mass of the main agent (i) It may be more than, preferably 10 parts by mass or less, more preferably 8 parts by mass or less.

  As a method of mixing the urethane resin composition, in the case of using the auxiliaries (iii), it is preferable to prepare the auxiliaries (iii) in which a polyol, water, a catalyst, a foam stabilizer, etc. are sufficiently mixed in advance. . For example, the main agent (i), the curing agent (ii), and the auxiliary agent (iii) are put into separate tanks of the mixing and casting machine, and the main agent (i) is preferably added to 40 to 80 ° C. There is a method of warming, heating the curing agent (ii) to preferably 40 to 120 ° C., heating the auxiliary agent (iii) to 30 to 70 ° C., and mixing each with a mixing and casting machine.

  Further, when the auxiliary agent (iii) is not used, other additives may be added to the essential main agent (i) or the curing agent (ii), but are preferably added to the curing agent (ii). Prepare a curing agent (ii) in which water, a catalyst, a foam stabilizer, etc. are well mixed with a compound having a group ([NH] group and / or [OH] group) containing an active hydrogen atom which reacts with an isocyanate group in advance. Keep it. For example, the main agent (i) and the curing agent (ii) are put into separate tanks of the mixing and casting machine, and the main agent (i) is preferably heated to 40 to 80 ° C. A) preferably heated to 30 to 70.degree. C. and mixing them with a mixing and casting machine.

  Examples of a method for producing a polishing pad from the urethane resin composition include a method of foaming and curing the urethane resin composition in a mold (preferably, in a mold) to obtain a foamed cured product, and further performing after curing. . If necessary, the resulting foam-cured product may be further molded. Specifically, after mixing the urethane resin composition with the mixing and casting machine, each component is discharged from the mixing and casting machine, and the resulting mixture is preheated to a temperature of 40 to 120 ° C. in a mold. Then, the mold lid is closed and, for example, foam curing is performed at a temperature of 50 to 130 ° C. for 10 minutes to 10 hours to obtain a foam cured product. Thereafter, the obtained foamed cured product is taken out, and after curing is preferably performed at 100 to 120 ° C. for 8 to 20 hours. The foam-cured product thus obtained can be sliced to form the polishing pad of the present invention.

  Although the thickness of the said polishing pad is suitably determined according to a use, it is preferable that it is the range of 0.6-3 mm, for example.

  In addition, as another method for producing a polishing pad using the urethane resin composition, for example, a main agent (i ') (hereinafter referred to as "fine agent") containing fine bubbles by the gas loading method of the main agent (i) (Abbreviated as bubble-containing main agent (i '))), the urethane composition containing the micro-bubble-containing main agent (i') and the curing agent (ii) is mixed, poured into a mold and cured To obtain a microcellular foam-containing molding, and then the molding is removed from the mold and sliced into a sheet.

  As a method of obtaining the microbubble-containing main agent (i ') from the main agent (i), for example, a non-reactive gas such as nitrogen, carbon dioxide gas, helium or argon is introduced into the main agent (i) And the method of introducing air bubbles.

  As a method of mixing the urethane composition, for example, the microbubble-containing main agent (i ') and the curing agent (ii) are put into respective separate tanks of the mixing and casting machine, and the microbubble-containing main agent is mixed (I ') is preferably heated to 40 to 80 ° C, the curing agent (ii) is preferably heated to 40 to 120 ° C, and each is mixed by a mixing and casting machine.

  Then, the respective components are discharged from the mixing and casting machine, and the obtained mixture is poured into a mold preheated to 40 to 120 ° C., and the lid of the mold is closed, for example, a temperature of 50 to 130 ° C. The mixture is allowed to foam and cure for 10 minutes to 10 hours to obtain a foamed molded product. Thereafter, the obtained foam molded product is taken out, and after cure is preferably performed at 100 to 120 ° C. for 8 to 20 hours.

  Next, a polishing pad is obtained by slicing the foam molding into a sheet at an appropriate thickness. Although the thickness of the polishing pad after slicing is suitably determined according to a use, it is the range of 0.6-3 mm, for example.

  Moreover, as another method of manufacturing a polishing pad using the said urethane composition, when mixing the said main ingredient (i) and hardening | curing agent (ii) by a mixing | blending caster, for example, a mixer part is non-reactive. Gas is introduced and mixed, and the mechanical floss-like mixture is poured into a mold and cured to obtain a foam, and then the foam is removed from the mold and sliced into a sheet.

  Furthermore, as another method for producing a polishing pad using the urethane resin composition, for example, hollow plastic spheres (microballoon having a diameter of 20 to 120 μm) are added to the main agent (i) or the curing agent (ii). And the main agent and the curing agent are mixed and cured to obtain a molded product containing hollow plastic spheres, and then sliced into a sheet.

  The polishing pad according to the present invention has a high polishing rate and high flatness (with few edges), and is an optical lens, a glass substrate for liquid crystal display (LCD), a glass substrate for hard disk (HDD), It is useful for polishing processes such as glass disks for recording devices, optical lenses, silicon wafers, semiconductor devices, etc. where high polishing rates and high flatness (edge drop) are required. In particular, it is useful for polishing a material having a Vickers hardness of 1500 or less, and in particular for polishing silicon wafers and glass.

Vickers hardness is a kind of index of indentation hardness, and a rigid body (indentor) made of diamond is indented against a test object and judged by the area of the indentation made at that time. As a test method, there is JIS-Z-2244. The approximate Vickers hardness of various types of polishing is approximately as follows.
Silicon carbide (SiC): 2300 to 2500, sapphire: 2300, silicon: 1050, quartz glass: 950, various glasses: 500 to 700.

  As a polishing method using the polishing pad of the present invention, for example, in the case of polishing a silicon wafer, a pad in which an object to be polished is compatible with a slurry while dropping a slurry (a weak basic colloidal silica aqueous solution) onto the polishing pad And pressure-pressing the plate, and operating (rotating) the surface plate on which the pad is attached to operate (rotation) for polishing (CMP polishing method using loose abrasive).

  Hereinafter, the present invention will be more specifically described by way of examples.

In the examples, the number average molecular weight of the polyol (a1) was measured by gel permeation chromatography (GPC method).
Measuring device: High-speed GPC device ("HLC-8220GPC" manufactured by Tosoh Corporation)
Column: The following columns (all manufactured by Tosoh Corporation) were used in series connection.
"TSKgel G5000" (7.8 mm ID × 30 cm) × 1 "TSK gel G 4000" (7.8 mm ID × 30 cm) × 1 "TSK gel G 3000" (7.8 mm ID × 30 cm) × 1 This “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 volume: 100 μL (tetrahydrofuran solution with a sample concentration of 0.4% by mass)
Standard sample: A standard curve was prepared using the following standard polystyrene.
(Standard polystyrene)
Tosoh Corporation "TSKgel standard polystyrene A-500"
Tosoh Corporation "TSKgel standard polystyrene A-1000"
Tosoh Corporation "TSKgel standard polystyrene A-2500"
Tosoh Corporation "TSKgel standard polystyrene A-5000"
Tosoh Corporation "TSKgel standard polystyrene F-1"
Tosoh Corporation "TSKgel standard polystyrene F-2"
Tosoh Corporation "TSKgel standard polystyrene F-4"
Tosoh Corporation "TSKgel standard polystyrene F-10"
Tosoh Corporation "TSKgel standard polystyrene F-20"
Tosoh Corporation "TSKgel standard polystyrene F-40"
Tosoh Corporation "TSKgel standard polystyrene F-80"
Tosoh Corporation "TSKgel standard polystyrene F-128"
Tosoh Corporation "TSKgel standard polystyrene F-288"
Tosoh Corporation "TSKgel standard polystyrene F-550"

Synthesis Examples 1 to 4 and Comparative Synthesis Examples 1 to 3 and 5 to 9: Urethane Prepolymers (A1) to (A4), (A′1) to (A′3), and (A′5) to (A ′) 9) Synthesis)
The polyisocyanate (b) shown in Table 1 was charged into a 5-liter 4-neck round bottom flask equipped with a nitrogen inlet tube, a condenser for cooling, a thermometer, and a stirrer, and stirring was started. Subsequently, the polyol (a1) shown in Table 1 was charged and mixed, and reaction was performed at 80 ° C. for 3 hours under a nitrogen atmosphere. Next, the short chain glycol (a2) shown in Table 1 is reacted at 80 ° C. for 3 hours while paying attention to heat generation, and the isocyanate group terminated urethane prepolymer (A1) to (A4), (A ′) of NCO equivalent shown in Table 1 1) to (A'3) and (A'5) to (A'9) were obtained.

(Composition example 5)
The polyisocyanate (b) shown in Table 1 was charged into a 5-liter 4-neck round bottom flask equipped with a nitrogen inlet tube, a condenser for cooling, a thermometer, and a stirrer, and stirring was started. Subsequently, the polyol (a1) shown in Table 1 was charged and mixed, and reaction was performed at 80 ° C. for 3 hours under a nitrogen atmosphere. Next, the short chain glycol (a2) shown in Table 1 was reacted at 80 ° C. for 3 hours while paying attention to heat generation to obtain an isocyanate group terminated urethane prepolymer having an NCO equivalent of 371. Next, a thin film distillation treatment was further performed to remove free TDI (unreacted TDI) from the obtained isocyanate group-terminated urethane prepolymer, to obtain an isocyanate group-terminated urethane prepolymer (A5) having an NCO equivalent of 435.

(Comparative Example 4)
In the same manner as in Synthesis Example 5, an isocyanate group-terminated urethane prepolymer having an NCO equivalent of 380 was obtained. Next, a thin film distillation treatment is further performed to remove free TDI (unreacted TDI) from the obtained isocyanate group-terminated urethane prepolymer, to obtain an isocyanate group-terminated urethane prepolymer (A′4) having an NCO equivalent of 438. The

In Tables 1 and 2,
Polytetramethylene glycol 1 (also referred to as "PTMG 1000") represents polytetramethylene glycol (number average molecular weight: 1,000),
Polytetramethylene glycol 2 (also referred to as "PTMG 2000") represents polytetramethylene glycol (number average molecular weight 2,000),
Polytetramethylene glycol 3 (also referred to as "PTMG 650") represents polytetramethylene glycol (number average molecular weight 650),
Polyoxypropylene polyol 1 (Asahi Glass Urethane “EL 430”) represents polyoxypropylene polyol (number of hydroxyl groups: 3, number average molecular weight 430),
Polyoxypropylene polyol 2 (manufactured by Asahi Glass Urethane "EL 410 NE") represents polyoxypropylene polyol (having 4 hydroxyl groups and a number average molecular weight of 410),
Polyoxypropylene polyol 3 (Asahi Glass Urethane “EL3030”) is a polyprooxypropylene polyol (number of hydroxyl groups: 3, number average molecular weight 3,000),
Polyoxypropylene polyol 4 ("EL 1030" manufactured by Asahi Glass Urethane) represents polyoxypropylene glycol (number of hydroxyl groups: 3, number average molecular weight: 1,000),
Polyoxybutylene glycol 1 (also referred to as “PBG 2000”) represents polyoxybutylene glycol (number average molecular weight 2,000),
Polybutylene adipate 1 (also referred to as "BGA A 2000") represents a polyester polyol (having 2 hydroxyl groups and a number average molecular weight of 2,000) consisting of 1,4 butanediol and adipic acid,
Polybutylene adipate 2 (also referred to as “BGA A 1000”) represents a polyester polyol (having 2 hydroxyl groups and a number average molecular weight of 1,000) consisting of 1,4 butanediol and adipic acid,
Polyisocyanate (T80) represents TDI (isomer ratio 80/20 of 2,4 / 2,6),
Polyisocyanate (T100) represents 2,4-TDI.

(Examples 1 to 5, Comparative Examples 1 to 9)
The isocyanate group-terminated urethane prepolymers (A1) to (A5) and (A′1) to (A′9) obtained in Synthesis Examples 1 to 5 and Comparative Synthesis Examples 1 to 9 are temperature-controlled to 80 ° C. (I) Next, the curing agent (MBOCA) was melted at 120 ° C. and adjusted in temperature to obtain a curing agent (ii). Furthermore, the temperature of the combination solution shown in Table 3 was adjusted at 35 ° C. to obtain auxiliary (iii).
Next, the number of main agent (i) shown in Table 4 is charged into the reaction vessel and the temperature is adjusted to 80 ° C. After that, 35 ° C. liquid C is charged with the number of parts shown in Table 3 The curing agent (ii) of ° C. was charged in the number of parts shown in Table 4 and immediately stirred with a high-speed mixer for 20 seconds. Pour 6000 parts of a mixed solution of main agent (i) / hardener (ii) / auxiliary agent (iii) mixed in a 500 × 500 × 40 mm mold thermostatted at 60 ° C., close the lid of the mold, and 60 ° C. After holding for 1 hour, the ingot-like foamed molded product was taken out. Further, the obtained ingot-like foam-molded article was subjected to after curing at 100 ° C. for 16 hours.
The obtained ingot-like foam-formed product was cut into a thickness of 1.5 mm with a slicer to obtain sheet-like polishing pads (P1) to (P5) and (P'1) to (P'8). The evaluation results of density, hardness, tan δ peak temperature at 120 to 200 ° C. in dynamic viscoelasticity measurement with 1 Hz measurement frequency, tan δ value, polishing rate, and edge deviation of the obtained polishing pad are shown in Tables 5-6. .

(Examples 6-8, comparative examples 10-11)
The isocyanate group-terminated urethane prepolymer shown in Table 4 was adjusted to a temperature of 80 ° C. and used as a main agent (i). The temperature of the combination solution (B1, B2) shown in Table 3 was adjusted at 40 ° C. to obtain a curing agent (ii). Next, after charging the main agent (i) in the number of parts shown in Table 4 into the reaction vessel and adjusting the temperature to 80 ° C., adding the parts shown in Table 4 at 40 ° C. The mixture was immediately stirred with a high-speed mixer for 20 seconds. After pouring 6000 parts of the mixed solution of main agent (i) / hardener (ii) mixed into a 500 × 500 × 40 mm mold whose temperature is adjusted to 60 ° C., closing the mold lid and holding at 60 ° C. for 1 hour , And an ingot-like foamed molded product was taken out. Further, the resulting ingot-like foam-molded article was subjected to after curing at 80 ° C. for 16 hours.

  The obtained ingot-like foam-formed product was cut into a thickness of 1.5 mm with a slicer to obtain sheet-like polishing pads (P6) to (P8) and (P'9) and (P'9) (P'10). The evaluation results of density, hardness, tan δ peak temperature at 120 to 200 ° C. in dynamic viscoelasticity measurement with 1 Hz measurement frequency, tan δ value, polishing rate, and edge deviation of the obtained polishing pad are shown in Tables 5-6. .

  The measurement method (evaluation method) of tan δ peak temperature, tan δ value, polishing rate and edge deviation is as follows.

[Method of measuring tan δ peak temperature and tan δ value]
Using a polishing pad with a thickness of 1.5 mm, measure tan δ peak temperature (also referred to as “loss factor peak temperature”) (° C.) by dynamic viscoelastic analysis in accordance with JIS K 7244 according to the following procedure. The visco-elasticity of a 1.5 mm thick polishing pad was evaluated.
The storage elastic modulus (E ′) and the loss elastic modulus (E ′ ′) of the polishing pad were measured using a visco-elastic spectrometer (model: DMS 6100, manufactured by SII Nano Technology Inc.) in a temperature range of −100 to 200 The temperature was measured in a tensile mode under conditions of a temperature rise rate of 5 ° C./min and a frequency of 1 Hz.
When E ′ ′ / E ′ is tan δ, the temperature at which tan δ reaches a maximum value in the range of 120 ° C. to 200 ° C. is “tan δ peak temperature (° C.)”, and E ′ ′ / E ′ at tan δ peak temperature is tan δ It is a value.
Measurement condition:
(Sample size) 5 x 60 x 1.5 mm
(Span) 20 mm
(Strain amount) 0.05%

[Evaluation method of polishing rate]
The polishing pad obtained in the examples and comparative examples was attached to one side of a double-sided tape, the surface plate of a polishing machine was attached to the other side of the double-sided tape, and the polishing rate was measured by the following apparatus, conditions and calculation formula.
Polishing machine: FAM 18 GPAW (manufactured by Speed Fam, Plate diameter: 457 m water-cooled type)
Polishing conditions:
(Pad pre-treatment) Dressing treatment (flattening and setting of the pad) was performed with a diamond dresser (# 100) until lines drawn vertically and horizontally at intervals of 2 cm with a red pencil disappeared on the pad surface. Water supply amount 200 ml / min (for polishing) 4 inch single crystal silicon wafer Thickness: 540 μm
(Silicon wafer support method) Ceramic block / microporous suede pad (water adsorption) silicon wafer (polish cooling water) 20 ° C
(Slurry) Colloidal silica solution Nita Haas Co., Ltd. “N6501” 20-fold diluted (Slurry flow rate) 100 ml / min (recirculation type)
(Plate rotation speed) 50 rpm (corotation type)
(Polishing pressure) 30 kPa
(Polishing time) 20 minutes (Polishing rate) It was calculated from the difference in weight of the polyurethane polishing pad before and after polishing.
That is, polishing rate (μm / min) = (weight of silicon wafer before polishing (g) −weight of silicon wafer after polishing (g)) × 10,000 / (density of single crystal silicon (g / cm ³ ) × silicon Wafer area (cm ² ) x polishing time (min))
Density of single crystal silicon = 2.329 g / cm ³
Silicon wafer area = 20.4 cm ²

[Method of evaluating rims]
After the evaluation of the polishing rate, the red dress process was performed for 1 hour with a diamond dresser (# 100). Then, it changed to the new to-be-polished body and grind | polished on the following grinding | polishing conditions. After completion of the polishing, the height of the object to be polished was measured with a spectral interference laser displacement meter.
Polishing conditions:
(For polishing) 4 inch single crystal silicon wafer thickness: 540 μm
(Silicon wafer support method) Ceramic block / wax / silicon wafer (polishing machine cooling water) 20 ° C
(Slurry) Colloidal silica solution Nita Haas Co., Ltd. “N6501” 20-fold diluted (Slurry flow rate) 100 ml / min (recirculation type)
(Plate rotation speed) 50 rpm (corotation type)
(Polishing pressure) 30 kPa
(Polishing time) 60 minutes Laser displacement meter conditions:
(Device) SI-F10 / KS-1100 (manufactured by KEYENCE CORPORATION)
(Measurement point) 101 × 101 = 10 201 points (measured as it is attached to the ceramic block)
(Analysis software) KS analyzer (Keyence Corporation)
(Edge evaluation site) Line segment (diameter) passing through silicon wafer center
(Hedge evaluation) Maximum height-It evaluated by the height of a 2 mm site | part from a left end.

In Table 3,
Polyoxypropylene polyol 3 (Asahi Glass Urethane “EL 3030”) represents polyoxypropylene glycol (number of hydroxyl groups: 3, number average molecular weight 3,000),
The aromatic aminochlorophenylmethane compound represents MBOCA (3,3'-dichloro-4,4-diaminophenylmethane), a mixture of its multimer and polyether polyol (active hydrogen equivalent: 189). TOYOCAT ET Ltd., represents a mixture of bis (dimethylaminoethyl) ether (70%) and dipropylene glycol (30%),
SH-193 represents a silicone foam stabilizer manufactured by Toray Dow Corning Co., Ltd.

  In Table 4, MBOCA represents 3,3'-dichloro-4,4-diaminophenylmethane.

The polishing pads of Examples 1 to 8 were the polishing pads of the present invention, and it was possible to obtain an object to be polished which has a high polishing rate and which is excellent in high flatness (with less edge deviation).
Comparative Examples 1 to 3, 5 and 7 have small tan δ values, Comparative Examples 4, 7 and 9 and 10 have low tan δ peak temperatures, and Comparative Example 6 has polytetramethylene glycol contained in the polyol component (a). The comparative example 8 had no tan δ peak temperature and could not simultaneously achieve high polishing rate and high flatness.

  In addition, as shown in FIG. 1, the cross section of the polishing pad of the present invention is fluffed, and it has been confirmed that a fine domain having a specific viscoelasticity is present. On the other hand, the cross section of the polishing pad of the comparative example was smooth as shown in FIG.

Claims (7)

It is a cured product of a urethane resin composition comprising a main agent (i) containing a urethane prepolymer (A) and a curing agent (ii),
The urethane prepolymer (A) is a reaction product of a polyol component (a) containing a polyol (a1) having a molecular weight of 300 or more and a short chain glycol (a2) having a molecular weight of less than 300 with polyisocyanate (b) With an isocyanate group,
The polyol component (a) contains polytetramethylene glycol at a content of 40% by mass or more and 90% by mass or less,
The content of the short chain glycol (a2) is 1% by mass or more in the polyol component (a),
The cured product has a tan δ peak in a range of 120 ° C. or more and 200 ° C. or less in dynamic viscoelasticity measurement with a measurement frequency of 1 Hz, and
The polishing pad characterized in that the peak value of tan δ in the range of 120 ° C. or more and 200 ° C. or less is 0.18 or more.   The polishing pad according to claim 1, wherein the short chain glycol (a2) having a pre-molecular weight of less than 300 is diethylene glycol.   The polishing pad according to claim 1 or 2, wherein the polyol (a1) is polytetramethylene glycol, and the content of polytetramethylene glycol in the polyol (a) is 60% by mass or more.   The polishing pad according to any one of claims 1 to 3, wherein the number average molecular weight of the polyol (a1) is 1,100 or more.   The polishing pad according to any one of claims 1 to 4, wherein the polyisocyanate (b) is an aromatic polyisocyanate.   The polishing pad according to any one of claims 1 to 5, wherein the curing agent (ii) is an aromatic amine compound. A urethane resin composition comprising a main agent (i) containing a urethane prepolymer (A) and a curing agent (ii),
The reaction product of a composition comprising a polyol component (a) containing a polyol (a1) having a molecular weight of 300 or more and a short chain glycol (a2) having a molecular weight of less than 300 and the polyisocyanate component (b). And has an isocyanate group at the end,
The short chain glycol is diethylene glycol,
In the polyol component (a), the content of the short chain glycol (a2) is 1% by mass or more,
The polyol component (a1) contains polytetramethylene glycol at a content of 40% by mass to 90% by mass,
The urethane resin composition for a polishing pad, wherein the number average molecular weight of the polyol (a1) is 1,100 or more.