阅读说明：本技术 树脂组合物、研磨垫、和研磨垫的制造方法 (Resin composition, polishing pad, and method for producing polishing pad ) 是由 石内隆仁 高桥信行 于 2019-01-21 设计创作，主要内容包括：本公开的目的在于,提供容易得到硬度适合化学机械研磨、且具有所希望的尺寸的细孔的研磨垫的树脂组合物,以及使用该树脂组合物而得的研磨垫和研磨垫的制造方法。一种树脂组合物,含有：氨基甲酸酯(甲基)丙烯酸酯(A)、不饱和树脂(B)、具有烯属不饱和键的烯属不饱和化合物(C)、和中空体(D),不饱和树脂(B)是乙烯基酯树脂和不饱和聚酯树脂中的至少一者,烯属不饱和化合物(C)不包括氨基甲酸酯(甲基)丙烯酸酯(A)和不饱和树脂(B),氨基甲酸酯(甲基)丙烯酸酯(A)的含量与不饱和树脂(B)的含量的质量比A：B为64：36～96：4,相对于氨基甲酸酯(甲基)丙烯酸酯(A)、不饱和树脂(B)、烯属不饱和化合物(C)的合计100质量份,中空体(D)的含量为0.7～9.0质量份。(An object of the present disclosure is to provide a resin composition that can easily obtain a polishing pad having a hardness suitable for chemical mechanical polishing and pores having a desired size, a polishing pad obtained using the resin composition, and a method for producing the polishing pad. A resin composition comprising: urethane (meth) acrylate (a), unsaturated resin (B), ethylenically unsaturated compound (C) having an ethylenically unsaturated bond, and hollow body (D), the unsaturated resin (B) being at least one of a vinyl ester resin and an unsaturated polyester resin, the ethylenically unsaturated compound (C) excluding the urethane (meth) acrylate (a) and the unsaturated resin (B), the mass ratio a of the content of the urethane (meth) acrylate (a) to the content of the unsaturated resin (B): b is 64: 36-96: and (4) the hollow body (D) is contained in an amount of 0.7 to 9.0 parts by mass per 100 parts by mass of the total of the urethane (meth) acrylate (A), the unsaturated resin (B), and the ethylenically unsaturated compound (C).)

1. A resin composition comprising:

urethane (meth) acrylate (A),

Unsaturated resin (B),

An ethylenically unsaturated compound (C) having an ethylenically unsaturated bond, and

a hollow body (D) having a hollow center,

the unsaturated resin (B) is at least one of a vinyl ester resin and an unsaturated polyester resin, the ethylenically unsaturated compound (C) excludes the urethane (meth) acrylate (A) and the unsaturated resin (B), the urethane (meth) acrylate (A) is represented by the following general formula,

in the general formula, R¹Is H or CH₃，R²Is a 2-valent hydrocarbon group which may have an ether bond, the hydrogen atom may be replaced with a substituent, R³Is a 2-valent hydrocarbon radical, R⁴Is a structural unit derived from a polyester polyol having a weight average molecular weight of 2000 to 8000, the number of repeating units n is an average value of the number basis of the whole of the urethane (meth) acrylate (A) contained in the resin composition, and is a real number of 1.00 or more,

a mass ratio of the content of the urethane (meth) acrylate (a) to the content of the unsaturated resin (B) a: b is 64: 36-96: 4,

the hollow body (D) is contained in an amount of 0.7 to 9.0 parts by mass per 100 parts by mass of the total of the urethane (meth) acrylate (A), the unsaturated resin (B) and the ethylenically unsaturated compound (C).

2. The resin composition as defined in claim 1, the hollow body (D) being a resin hollow sphere.

3. The resin composition according to claim 1 or 2, wherein the ethylenically unsaturated compound (C) is contained in an amount of 40 to 200 parts by mass based on 100 parts by mass of the total of the urethane (meth) acrylate (A) and the unsaturated resin (B).

4. A resin composition according to any one of claims 1 to 3, wherein n has a value of 1.00 to 6.00.

5. The resin composition according to any one of claims 1 to 4, wherein R is represented by the formula²Is an alkylene group having 2 to 6 carbon atoms.

6. The resin composition according to any one of claims 1 to 5, wherein R is represented by the formula³Is a cycloalkylene group or an alkylene group having 5 to 15 carbon atoms.

7. The resin composition according to any one of claims 1 to 6, wherein R is represented by the formula⁴The polyester polyol in (1) is a condensate of an aliphatic diol and an aliphatic dibasic acid.

8. The resin composition according to any one of claims 1 to 7, wherein the unsaturated resin (B) is an epoxy (meth) acrylate.

9. The resin composition according to any one of claims 1 to 8, containing an inorganic filler other than the hollow body (D).

10. The resin composition according to claim 9, wherein the inorganic filler is contained in an amount of 10 to 200 parts by mass based on 100 parts by mass of the total of the urethane (meth) acrylate (A), the unsaturated resin (B) and the ethylenically unsaturated compound (C).

11. The resin composition according to any one of claims 1 to 10, which is a resin composition for a polishing pad.

12. A polishing pad comprising a cured product of the resin composition according to any one of claims 1 to 10.

13. A method for manufacturing a polishing pad includes the steps of: a step of molding and curing the resin composition according to any one of claims 1 to 10, and a step of grinding the surface of the cured resin composition.

Technical Field

The present disclosure relates to a resin composition, a polishing pad, and a method for manufacturing a polishing pad.

Background

Polishing sheets of 1 type as a polishing pad were produced by using a nonwoven fabric or woven fabric made of synthetic fibers, synthetic rubber or the like, or a polyester film or the like as a base material, applying a polyurethane solution thereon, forming a porous layer having continuous pores by a wet coagulation method, and grinding and removing the skin layer as necessary. The polishing sheet has been widely used as a polishing pad for use in rough polishing to finish polishing for surface precision polishing of electronic parts such as liquid crystal glass, glass plates, photomask silicon wafers, CCDs, and cover glass. With the recent development of measuring instruments for precision polishing surfaces, the quality demanded of users has also increased, and polishing pads capable of polishing with higher precision have been demanded.

Chemical Mechanical Polishing (CMP) has been conventionally used for planarization of precision devices such as magnetic disk substrates, optical lenses, and semiconductor wafers. In the CMP method, abrasive grains (abrasive particles) are generally dispersed in an alkaline solution or an acidic solution, and the resulting slurry (polishing liquid) is supplied between the processing surface of the object to be polished and the polishing pad. During polishing, the object to be polished is planarized by the mechanical polishing action of the abrasive grains in the slurry and the chemical polishing action of the alkaline solution or the acidic solution.

As a polishing pad used in such a CMP method, particularly in finish polishing, a polishing pad using a porous soft polyurethane foam having excellent abrasion resistance as a polishing layer is known. However, this type of polishing pad has a polishing layer with high flexibility and is easily compressed and deformed. Therefore, the phenomenon of over-polishing, so-called end-drop, occurs in which the polishing layer follows the shape of the end of the object to be polished during polishing, and the end of the object to be polished is polished more than the center. Further, the fine pores present on the surface of the polishing layer are partially clogged by friction during polishing, and thus there is a problem that polishing damage occurs on the surface to be polished, and the polishing rate decreases with time.

As a technique for preventing the end portion from sagging, it has been studied to increase the hardness of the polishing layer of the polishing pad. For example, patent document 1 describes a polishing cloth in which a nonwoven fabric obtained by mixing polyester fibers and heat-fusible filaments is impregnated with a resin. The resin used for impregnation here is a urethane resin, and after impregnation, the resin is cured. Patent document 2 describes that in a polishing pad made of foamed polyurethane, the connection between cells is suppressed, and the respective cells are separated.

Disclosure of Invention

Problems to be solved by the invention

In polishing by the CMP method, a material having very high hardness such as diamond is used as abrasive grains. In addition, there is typically variation in the size and shape of the abrasive particles. Due to the nature of the abrasive grains, when the polishing pad is too hard, the polishing pad cannot absorb a force applied to a part of large abrasive grains or sharp abrasive grains, and the surface of the object to be polished is locally subjected to an excessive load, which may damage the surface of the object to be polished. Therefore, the polishing pad is required to have not only sufficient hardness but also flexibility to the extent that it can absorb an excessive force applied to the abrasive grains in order to suppress the end portion sagging.

Further, it has been found that the size and distribution of the fine pores in the polishing pad have a great influence on the polishing accuracy, and it is important to develop a technique for controlling them.

However, the polishing cloth of patent document 1 has difficulty in controlling the size and distribution of pores in the production process. In the method for producing a polishing pad of patent document 2, it is difficult to control the size of each bubble and the variation thereof, and it is difficult to avoid the size variation of the bubbles contained in the polishing pad.

In view of the above problems, an object of the present disclosure is to provide a resin composition that can easily obtain a polishing pad having a hardness suitable for chemical mechanical polishing and pores having a desired size, a polishing pad obtained using the resin composition, and a method for producing the polishing pad.

Means for solving the problems

The present invention includes the following modes.

[1] A resin composition comprising:

urethane (meth) acrylate (A),

Unsaturated resin (B),

An ethylenically unsaturated compound (C) having an ethylenically unsaturated bond, and

a hollow body (D) having a hollow center,

the unsaturated resin (B) is at least one of a vinyl ester resin and an unsaturated polyester resin, the ethylenically unsaturated compound (C) excludes the urethane (meth) acrylate (A) and the unsaturated resin (B), the urethane (meth) acrylate (A) is represented by the following general formula,

in the general formula, R¹Is H or CH₃，R²Is a 2-valent hydrocarbon group which may have an ether bond, the hydrogen atom may be replaced with a substituent, R³Is a 2-valent hydrocarbon radical, R⁴Is a structural unit derived from a polyester polyol having a weight average molecular weight of 2000 to 8000, the number of repeating units n is an average value of the number basis of the whole of the urethane (meth) acrylate (A) contained in the resin composition, and is a real number of 1.00 or more,

a mass ratio of the content of the urethane (meth) acrylate (a) to the content of the unsaturated resin (B) a: b is 64: 36-96: 4,

the hollow body (D) is contained in an amount of 0.7 to 9.0 parts by mass per 100 parts by mass of the total of the urethane (meth) acrylate (A), the unsaturated resin (B) and the ethylenically unsaturated compound (C).

[2] The resin composition as recited in [1], wherein the hollow body (D) is a resin hollow sphere.

[3] The resin composition according to [1] or [2], wherein the ethylenically unsaturated compound (C) is contained in an amount of 40 to 200 parts by mass based on 100 parts by mass of the total of the urethane (meth) acrylate (A) and the unsaturated resin (B).

[4] The resin composition according to any one of [1] to [3], wherein n is 1.00 to 6.00.

[5]As in [1]]～[4]The resin composition of any one of (1), wherein R is²Is an alkylene group having 2 to 6 carbon atoms.

[6]As in [1]]～[5]The resin composition of any one of (1), wherein R is³Is a cycloalkylene group or an alkylene group having 5 to 15 carbon atoms.

[7]As in [1]]～[6]The resin composition of any one of (1), R of the general formula⁴The polyester polyol in (1) is a condensate of an aliphatic diol and an aliphatic dibasic acid.

[8] The resin composition according to any one of [1] to [7], wherein the unsaturated resin (B) is an epoxy (meth) acrylate.

[9] The resin composition according to any one of [1] to [8], which contains an inorganic filler other than the hollow body (D).

[10] The resin composition according to [9], wherein the inorganic filler is contained in an amount of 10 to 200 parts by mass based on 100 parts by mass of the total of the urethane (meth) acrylate (A), the unsaturated resin (B) and the ethylenically unsaturated compound (C).

[11] The resin composition according to any one of [1] to [10], which is a resin composition for a polishing pad.

[12] A polishing pad comprising a cured product of the resin composition according to any one of [1] to [10].

[13] A method for manufacturing a polishing pad, comprising the steps of: a step of molding and curing the resin composition according to any one of [1] to [10], and a step of grinding the surface of the cured resin composition.

Effects of the invention

According to the present disclosure, a resin composition from which a polishing pad having a hardness suitable for chemical mechanical polishing and pores of a desired size can be easily obtained, a polishing pad using the resin composition, and a method for producing the polishing pad are provided.

Detailed Description

The resin composition, the polishing pad, and the method for producing the polishing pad of the present invention will be specifically described below. The present invention is not limited to the embodiments described below.

In the following description, "ethylenically unsaturated bond" means a double bond formed between carbon atoms other than those forming an aromatic ring.

"weight average molecular weight" and "number average molecular weight" are standard polystyrene conversion values determined by Size Exclusion Chromatography (SEC), for example Gel Permeation Chromatography (GPC).

The "median diameter" refers to a particle diameter corresponding to a volume-based particle diameter distribution obtained by a laser diffraction/scattering method, when the particle diameter distribution is integrated to 50%.

"(meth) acrylate" means acrylate or methacrylate, and "(meth) acrylic acid" means acrylic acid or methacrylic acid.

< 1. resin composition >

The resin composition of an embodiment contains a urethane (meth) acrylate (a), an unsaturated resin (B) which is at least one selected from a vinyl ester resin and an unsaturated polyester, an ethylenically unsaturated compound (C) having an ethylenically unsaturated bond other than the urethane (meth) acrylate (a) and the unsaturated resin (B), and a hollow body (D). The blending ratio of the urethane (meth) acrylate (A) and the unsaturated resin (B), and the content of the hollow body (D) are described in items 1 to 3 and items 1 to 5, respectively, later. Hereinafter, each component contained in the resin composition of the present embodiment will be described.

< 1-1. urethane (meth) acrylate (A) >

The urethane (meth) acrylate (a) is represented by the following general formula.

In the above formula, R¹Is H or CH₃，R²Is a 2-valent hydrocarbon group which may have an ether bond, the hydrogen atom may be replaced with a substituent, R³Is a 2-valent hydrocarbon radical, R⁴Is a structural unit derived from a polyester polyol having a weight average molecular weight of 2000 to 8000, wherein the number n of repeating units is an average value based on the number of the entire urethane (meth) acrylate (A) contained in the resin composition, and is a real number of 1.00 or more.

In the above formula R¹Is H or CH₃Preferably, it is H.

In the above formula, R²Is a 2-valent hydrocarbon group which may have an ether bond, and the hydrogen atom may be replaced with a substituent. As R²Examples of the hydrocarbon group of (2) include an alkylene group, a cycloalkylene group, and an arylene group, and these hydrocarbon groups may have a branch. R²Preferably an alkylene group having 2 to 6 carbon atoms or an alkylene group having 2 to 6 carbon atoms wherein a hydrogen atom is substituted with a substituent such as a phenyl group, a phenoxy group, a (meth) acryloyloxy group or the like. Particularly preferred is R²Is an ethylene group.

R¹And R²Is derived from a (meth) acrylate CH containing a hydroxyl group₂＝C(R¹)C(O)OR²Structure of OH. As hydroxyl-containing (meth) acrylates CH₂＝C(R¹)C(O)OR²Examples of OH include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl acrylate, 2-hydroxybutyl methacrylate, phenoxyhydroxypropyl acrylate, phenoxyhydroxypropyl methacrylate, trimethylolpropane diacrylate, trimethylolpropane dimethacrylate, dipropylene glycol monoacrylate and dipropylene glycol monomethacrylate. These containThe (meth) acrylate having a hydroxyl group may be used alone or in combination of 2 or more. The hydroxyl group-containing (meth) acrylate is preferably 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl acrylate, or 2-hydroxybutyl methacrylate, more preferably 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, or 2-hydroxybutyl acrylate, and still more preferably 2-hydroxyethyl acrylate.

In the above general formula, R³Is a 2-valent hydrocarbon group. R³The number of carbon atoms contained in (A) is preferably 5 to 15. As R³The hydrocarbon group of (b) is preferably a cycloalkylene group or an arylene group. The hydrogen atoms of these groups may be replaced by alkyl groups.

R³Is derived from a diisocyanate compound OCN-R³-structure of NCO. As diisocyanate compounds OCN-R³Examples of-NCO include isophorone diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate and the like. These diisocyanate compounds may be used alone or in combination of 2 or more. The diisocyanate compound is preferably isophorone diisocyanate, toluene diisocyanate, xylylene diisocyanate, or hydrogenated xylylene diisocyanate, and more preferably isophorone diisocyanate.

In the above formula, R⁴Is from polyester polyol HO-R with the weight average molecular weight of 2000-8000⁴-structural units of OH. Polyester polyol HO-R⁴OH is a condensate obtained by, for example, a condensation reaction of a diol with a dibasic acid. The diol is preferably an aliphatic diol, more preferably a diol having hydroxyl groups at both ends of a linear hydrocarbon, and particularly preferably a diol having no unsaturated bond. Examples of the diol include ethylene glycol, propylene glycol, dipropylene glycol, and hexylene glycol, and ethylene glycol is particularly preferable. The dibasic acid is preferably an aliphatic group, and more preferably an aliphatic group having no branched or cyclic structure. The dibasic acid includes oxalic acid, fumaric acid, and succinic acidAdipic acid, sebacic acid, and the like, with adipic acid being particularly preferred. Both the aliphatic diol and the aliphatic dibasic acid can increase the elongation of the urethane (meth) acrylate (a) and improve the toughness of the resulting molded article.

The lower limit of the weight average molecular weight of the polyester polyol is 2000. This can increase the elongation of the urethane (meth) acrylate (a) and improve the toughness of the resulting molded article. From this viewpoint, the weight average molecular weight of the polyester polyol is preferably 3000 or more, and more preferably 4000 or more.

The upper limit of the weight average molecular weight of the polyester polyol is 8000. Thus, a molded article having sufficient strength can be obtained. From such a viewpoint, the weight average molecular weight of the polyester polyol is preferably 7000 or less, and more preferably 6000 or less. The weight average molecular weight is a polystyrene equivalent value measured by size exclusion chromatography as described above.

In the above formula, n is a real number of 1.00 or more in the number of repetitions of a constituent unit in parentheses in the above formula. The value of n is based on the number average molecular weight M of the urethane (meth) acrylate (A) contained in the resin composition_nAThe calculation is performed, for example, as follows. When the molecular weight of the part outside the middle brackets in the above general formula is denoted as M₁The molecular weight of the constituent unit in parentheses is denoted as M₂Then according to M_nA＝M₁+nM₂And (5) obtaining the value of n. Here again, M₂Is a value obtained based on the number average molecular weight of the polyester polyol. Further, n is obtained based on the number average molecular weight, and it can be understood that n is an average value based on the number of the entire urethane (meth) acrylate (a), and is not limited to an integer.

The value of n is preferably 6.00 or less. When the value of n is 6.00 or less, the viscosity of the urethane (meth) acrylate (A) can be prevented from increasing, and good workability can be ensured. From such a viewpoint, the value of n is more preferably 5.00 or less, and still more preferably 4.00 or less.

Examples of the method for producing the urethane (meth) acrylate (a) include the following methods: reacting a diisocyanate compound OCN-R³-NCO andpolyester polyol HO-R⁴-OH, synthesizing a molecule having isocyanate groups at both ends, and reacting with a (meth) acrylate CH having a hydroxyl group in the molecule₂＝C(R¹)C(O)OR²OH reaction method, etc. In the step of synthesizing a molecule having isocyanate groups at both ends, the diisocyanate compound is preferably added in an excess amount with respect to the polyester polyol, that is, so that the molar ratio of NCO groups/OH groups is more than 1.

< 1-2. unsaturated resin (B) >

The unsaturated resin (B) is at least one selected from the group consisting of vinyl ester resins and unsaturated polyesters. That is, the unsaturated resin (B) is a vinyl ester resin, an unsaturated polyester, or a mixture of a vinyl ester resin and an unsaturated polyester.

[1-2-1. vinyl ester resin ]

The vinyl ester resin is preferably an epoxy (meth) acrylate obtained by esterification of an epoxy resin and an α, β -unsaturated monocarboxylic acid.

Examples of the epoxy resin include diglycidyl ethers of bisphenols such as bisphenol a, bisphenol AD, and bisphenol F, and high molecular weight homologues thereof, phenol novolac type polyglycidyl ethers, and cresol novolac type polyglycidyl ethers. An epoxy resin obtained by reacting a phenol compound such as bisphenol a, bisphenol AD, bisphenol F, or bisphenol S with the glycidyl ether or an aliphatic epoxy resin may be used in the synthesis process. Among these, the use of bisphenol a epoxy resin is preferable because it provides a vinyl ester resin which can provide a cured product excellent in mechanical strength and chemical resistance.

Examples of the α, β -unsaturated monocarboxylic acid include acrylic acid and methacrylic acid. As the α, β -unsaturated monocarboxylic acid, crotonic acid, α -methylcrotonic acid, cinnamic acid, and the like can be used. Among these, the use of (meth) acrylic acid is preferable because it provides a vinyl ester resin which can provide a cured product having excellent mechanical strength and chemical resistance.

As a preferred synthesis example of the epoxy (meth) acrylate, there is a method of: the diglycidyl ether of bisphenol A and the alpha, beta-unsaturated monocarboxylic acid are esterified at a ratio of carboxyl group/epoxy group of 1.05 to 0.95 at 80 to 140 ℃. Further, a catalyst may be used as necessary. Examples of the catalyst include tertiary amines such as benzyldimethylamine, triethylamine, N-dimethylaniline, triethylenediamine, and 2,4, 6-tris (dimethylaminomethyl) phenol, quaternary ammonium salts such as trimethylbenzylammonium chloride, and metal salts such as lithium chloride.

The weight average molecular weight of the vinyl ester resin is preferably 1,000 to 6,000, more preferably 1,000 to 5,000, and still more preferably 1,000 to 4,000. If the weight average molecular weight of the vinyl ester resin is 1,000 to 6,000, the moldability of the resin composition becomes better. Further, the weight average molecular weight is, as previously stated, a polystyrene equivalent value measured by size exclusion chromatography.

[1-2-2. unsaturated polyester resin ]

The unsaturated polyester resin is obtained by polycondensation of a polyvalent alcohol, an unsaturated polybasic acid, and a saturated polybasic acid added as needed, and the kind of these is not particularly limited. The unsaturated polybasic acid means a polybasic acid having an ethylenically unsaturated bond, and the saturated polybasic acid is a polybasic acid having no ethylenically unsaturated bond. The unsaturated polyester resin may be present in only 1 kind, or may be present in 2 or more kinds.

Examples of the polyvalent alcohol include ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, pentanediol, hexanediol, neopentyl glycol, hydrogenated bisphenol a, glycerin, and the like. Among these, propylene glycol and hydrogenated bisphenol a are preferred. The polyvalent alcohols may be used alone or in combination of 2 or more.

Examples of the unsaturated polybasic acid include maleic acid, maleic anhydride, fumaric acid, citraconic acid, and itaconic acid. The unsaturated polybasic acids may be used alone or in combination of 2 or more. Among these, maleic anhydride and fumaric acid are preferable.

Examples of the saturated polybasic acid include phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, chlorendic acid, succinic acid, adipic acid, sebacic acid, tetrachlorophthalic anhydride, tetrabromophthalic anhydride, endomethylenetetrahydrophthalic anhydride, and the like. Among them, phthalic acid is preferred. The saturated polybasic acids may be used alone or in combination of 2 or more.

The weight average molecular weight of the unsaturated polyester resin is preferably 6,000 to 35,000, more preferably 6000 to 20000, and still more preferably 8000 to 15000. If the weight average molecular weight is 6000 to 35000, the moldability of the resin composition becomes better. The weight average molecular weight is a polystyrene equivalent value measured by size exclusion chromatography, as described above.

The unsaturated polyester resin preferably has an unsaturation degree of 50 to 100 mol%, more preferably 60 to 100 mol%, and still more preferably 70 to 100 mol%. When the degree of unsaturation is within the above range, moldability of the resin composition becomes better. The unsaturation degree of the unsaturated polyester resin can be calculated by substituting the mole numbers of the unsaturated polybasic acid and the saturated polybasic acid used as raw materials into the following formula.

Unsaturation degree (% by mole) { (the number of moles of unsaturated polybasic acid)/(the number of moles of unsaturated polybasic acid + the number of moles of saturated polybasic acid) } × 100

< 1-3. mixing ratio of urethane (meth) acrylate (A) and unsaturated resin (B) >

In order to absorb an excessive force applied to the abrasive grains, the polishing pad is preferably such that a cured product of the resin composition is not excessively hard. In this regard, the greater the content of the urethane (meth) acrylate (a) relative to the content of the unsaturated resin (B), the lower the hardness of the resin composition after curing. Therefore, the mass ratio a of the content of the urethane (meth) acrylate (a) to the content of the unsaturated resin (B) contained in the resin composition: b is 64: 36 or more (i.e., A/B of 64/36 or more), preferably 68: 32 or more (i.e., a/B of 68/32 or more), more preferably 70: 30 or more (i.e., A/B is 70/30 or more).

In order to obtain a polishing pad in which the end portion of an object to be polished is prevented from sagging, the cured product of the resin composition is preferably hard. In this regard, the smaller the content of the urethane (meth) acrylate (a) relative to the content of the unsaturated resin (B), the higher the hardness of the resin composition after curing. In order to impart sufficient hardness to a cured product of the resin composition. Mass ratio of content of urethane (meth) acrylate (a) to content of unsaturated resin (B) a: b is 96: 4 or less (i.e., A/B of 96/4 or less), preferably 94: 6 or less (i.e., A/B of 94/6 or less), more preferably 90: 10 or less (i.e., A/B is 90/10 or less).

< 1-4. ethylenically unsaturated Compound (C) >

The ethylenically unsaturated compound (C) is not particularly limited as long as it is a compound having an ethylenically unsaturated bond copolymerizable with at least one selected from the group consisting of the urethane (meth) acrylate (a) and the unsaturated resin (B), and is preferably copolymerizable with both the urethane (meth) acrylate (a) and the unsaturated resin (B).

Examples of the ethylenically unsaturated compound (C) include aromatic monomers such as styrene, vinyltoluene, and divinylbenzene, 2-hydroxyethyl methacrylate, diacrylate of polyoxyalkylene, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, and acrylate monomers such as methyl methacrylate, and oligomers obtained by bonding a plurality of the above monomers. Among these, styrene and methyl methacrylate are preferable, and styrene is particularly preferable, from the viewpoint of reactivity of the urethane (meth) acrylate (a) and the unsaturated resin (B). The ethylenically unsaturated compound (C) may be used alone or in combination of 2 or more.

The content of the ethylenically unsaturated compound (C) is preferably 40 parts by mass or more per 100 parts by mass of the total of the urethane (meth) acrylate (a) and the unsaturated resin (B). This makes it possible to easily control the viscosity of the resin composition. From this viewpoint, the content of the ethylenically unsaturated compound (C) is more preferably 50 parts by mass or more, and still more preferably 60 parts by mass or more.

The content of the ethylenically unsaturated compound (C) is preferably 200 parts by mass or less based on 100 parts by mass of the total of the urethane (meth) acrylate (a) and the unsaturated resin (B). This can improve the mechanical strength of the cured resin composition. From this viewpoint, the content of the ethylenically unsaturated compound (C) is more preferably 150 parts by mass or less, and still more preferably 120 parts by mass or less.

< 1-5. hollow body (D) >

The hollow body (D) is a particle having a void inside. After curing the resin composition described later, the surface of the cured product is ground and flattened to remove the surface of the hollow body (D), and pores from the hollow body (D) are formed on the surface of the cured product (e.g., polishing pad). When the cured product is used as a polishing layer of a polishing pad, the pores from the hollow body (D) present on the surface of the polishing layer can function to hold abrasive grains (hereinafter, also referred to as "abrasive particles") contained in the polishing agent. By appropriately selecting the size and distribution of the hollow bodies (D) contained in the resin composition, the size and distribution of the fine pores present on the surface of the polishing pad produced using the resin composition can be accurately and easily controlled.

The hollow body (D) preferably has a median diameter of 50 μm or more. This can reliably retain the abrasive particles in the pores. From this viewpoint, the median diameter of the hollow body (D) is more preferably 60 μm or more, and still more preferably 70 μm or more.

The hollow body (D) preferably has a median diameter of 200 μm or less. This can limit the amount of abrasive grains held in 1 pore, and suppress a decrease in the polishing performance. From this viewpoint, the median diameter of the hollow body (D) is more preferably 150 μm or less, and still more preferably 120 μm or less.

The narrower the size distribution of the hollow body (D), the narrower the size distribution of the pores formed on the polishing pad made of the resin composition. If the size distribution of the fine pores is narrow, the amount of the abrasive grains held therein entering the fine pores is also uniform, that is, the amount of the abrasive grains exposed from the surface of the polishing pad is also uniform, and the load applied to the object to be polished is more uniformly dispersed. From this viewpoint, the standard deviation of the number-based particle diameter of the hollow bodies (D) is preferably 20.0 μm or less, more preferably 10.0 μm or less, and still more preferably 8.0 μm or less. The standard deviation of the number-based particle diameters of the hollow bodies (D) can be calculated by measuring the particle diameters of a predetermined number or more of the hollow bodies (D) using a visual observation device such as a microscope, for example, and obtaining a predetermined number of particle diameter values. The predetermined number is a statistical angle, and is preferably 30 or more.

However, the size and distribution of the hollow body (D) are not limited to those described above, and may be appropriately designed according to the type of the polishing agent used, the type of polishing process, and the like. The shape of the hollow body (D) is generally spherical, but may be appropriately selected depending on the type of the polishing agent used, the type of the polishing step, and the like.

Examples of the material of the hollow body (D) include glass hollow spheres, silica hollow spheres, alumina hollow spheres, ceramic hollow spheres, white sand hollow spheres, resin hollow spheres, and the like, and among these, resin hollow spheres are preferable. Examples of the resin for forming the resin hollow sphere include thermosetting resins such as phenol resin, epoxy resin, and urea resin, and thermoplastic resins such as polystyrene, polyvinylidene chloride, and acrylonitrile resin.

In order to suppress the formation of scratches on the surface of the object to be polished, it is preferable to disperse the load applied to the surface of the object to be polished. Therefore, in order to retain the polishing particles, a sufficient number of pores are preferably formed on the surface of the polishing pad. The number of pores on the surface of the polishing pad increases in accordance with the increase in the amount of the hollow body (D) added to the resin composition. Therefore, the content of the hollow body (D) in the resin composition is 0.7 parts by mass or more per 100 parts by mass of the total of the urethane (meth) acrylate (a), the unsaturated resin (B), and the ethylenically unsaturated compound (C). From this viewpoint, the content of the hollow body (D) is preferably 1.0 part by mass or more, and more preferably 2.0 parts by mass or more.

In the resin composition, the content of the hollow body (D) is 9.0 parts by mass or less with respect to 100 parts by mass of the total of the urethane (meth) acrylate (a), the unsaturated resin (B), and the ethylenically unsaturated compound (C). In this way, a polishing pad produced using the resin composition can be ensured to have sufficient hardness. From this viewpoint, the content of the hollow body (D) is preferably 7.0 parts by mass or less, and more preferably 5.0 parts by mass or less.

< 1-6. other Components >

The resin composition may contain, in addition to the above-mentioned components (a) to (D), additives such as an inorganic filler other than the hollow body (D), a curing agent, a curing accelerator, a low shrinkage agent, a release agent, a thickener, a colorant, and a polymerization inhibitor, and the kind of the additives is not limited to these. These additives may be present in accordance with the respective purposes within a range not to impair the effects of the present invention. The specific additive is added in such an amount that the total amount of the contents of the urethane (meth) acrylate (a), the unsaturated resin (B), and the ethylenically unsaturated compound (C) in the resin composition is preferably 25.0% by mass or more, more preferably 35.0% by mass or more, and still more preferably 45.0% by mass or more.

The inorganic filler is selected according to the functions required, for example, to adjust the viscosity of the resin composition to a viscosity suitable for handling and to improve the moldability of the resin composition. Examples of the inorganic filler include aluminum hydroxide, barium sulfate, talc, kaolin, calcium sulfate, calcium carbonate, magnesium oxide, magnesium hydroxide, calcium hydroxide, and calcium oxide. Among these, calcium carbonate, aluminum hydroxide and talc are preferred because they are inexpensive, and calcium carbonate and aluminum hydroxide are more preferred. The inorganic filler may be used alone or in combination of 2 or more.

The median diameter of the inorganic filler is preferably 1 to 100 μm, more preferably 1 to 60 μm, and still more preferably 1 to 50 μm from the viewpoint of the viscosity of the resin composition when a cured product of the resin composition is formed. The larger the median diameter of the inorganic filler is, the more the aggregation of particles can be suppressed. Therefore, the median diameter of the inorganic filler is preferably 1 μm or more. On the other hand, the smaller the median diameter of the inorganic filler, the more moldability of the resin composition improves. Therefore, the median diameter of the inorganic filler is preferably 100 μm or less, more preferably 60 μm or less, and still more preferably 50 μm or less.

The inorganic filler may be spherical or flat, but is preferably spherical. When the inorganic filler is spherical particles, the specific surface area is small, and therefore, the viscosity of the resin composition can be effectively reduced when a cured product of the resin composition is formed. When the viscosity of the resin composition is low, the resin composition can be sufficiently filled in a mold when the resin composition is molded using the mold.

The higher the content of the inorganic filler, the higher the viscosity of the resin composition, and the separation of the hollow body (D) due to the difference in specific gravity from other components can be suppressed, and the moldability of the resin composition becomes better. From such a viewpoint, the content of the inorganic filler is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, and still more preferably 30 parts by mass or more, based on 100 parts by mass of the total of the urethane (meth) acrylate (a), the unsaturated resin (B), and the ethylenically unsaturated compound (C).

The smaller the content of the inorganic filler, the larger the number of pores capable of holding the abrasive particles. From such a viewpoint, the content of the inorganic filler is preferably 200 parts by mass or less, more preferably 100 parts by mass or less, and still more preferably 80 parts by mass or less, based on 100 parts by mass of the total of the urethane (meth) acrylate (a), the unsaturated resin (B), and the ethylenically unsaturated compound (C).

Examples of the curing agent include peroxides such as diacyl peroxide, peroxyester, hydrogen peroxide, dialkyl peroxide, ketone peroxide, peroxyketal, alkyl peroxyester, peroxycarbonate, and the like. Among these peroxides, tert-butyl peroctoate, benzoyl peroxide, 1-dibutylperoxy-3, 3, 5-trimethylcyclohexane, tert-butylperoxyisopropyl carbonate, tert-butylperoxybenzoate, dicumyl peroxide, and di-tert-butyl peroxide are preferable. These curing agents may be used alone or in combination of 2 or more. The amount of the curing agent to be added is preferably 0.5 to 2.0 parts by mass, and more preferably 0.6 to 1.5 parts by mass, based on 100 parts by mass of the total of the urethane (meth) acrylate (a), the unsaturated resin (B), and the ethylenically unsaturated compound (C).

Examples of the curing accelerator include metal soaps such as cobalt naphthenate, cobalt octylate, zinc octylate, vanadium octylate, copper naphthenate, and barium naphthenate, metal chelates such as vanadium acetoacetate, cobalt acetoacetate, and iron acetylacetonate, N-substituted anilines such as aniline, N-dimethylaniline, N-diethylaniline, and N, N-bis (hydroxyethyl) aniline, m-toluidine, p-toluidine, N-ethyl-m-toluidine, N-dimethyl-p-toluidine, N-bis (2-hydroxyethyl) -p-toluidine, N-substituted-p-toluidine such as N, N-bis (2-hydroxypropyl) -p-toluidine, 4- (N, N-dimethylamino) benzaldehyde, and the like, 4- (N, N-substituted amino) benzaldehyde such as 4- [ N, N-bis (2-hydroxyethyl) amino ] benzaldehyde or 4- (N-methyl-N-hydroxyethylamino) benzaldehyde, triethanolamine, diethylenetriamine, pyridine, 4-phenylmorpholine, piperidine or diethanolaniline, and cobalt octylate is preferable among these. These curing accelerators may be used alone or in combination of 2 or more.

The low shrinkage agent is preferably a thermoplastic resin, and examples thereof include polystyrene, polyethylene, polymethyl methacrylate, polyvinyl acetate, saturated polyester, and polycaprolactone. The low shrinkage agent may be used alone or in combination of 2 or more. The amount of the low shrinkage agent added is preferably 10 to 20 parts by mass based on 100 parts by mass of the total of the urethane (meth) acrylate (a), the unsaturated resin (B), and the ethylenically unsaturated compound (C).

Examples of the release agent include stearic acid, oleic acid, zinc stearate, calcium stearate, aluminum stearate, magnesium stearate, stearamide, oleamide, silicone oil, and synthetic wax. The release agent may be used alone or in combination of 2 or more. The amount of the release agent to be added is preferably 3.0 to 8.0 parts by mass, more preferably 3.5 to 7.0 parts by mass, based on 100 parts by mass of the total of the urethane (meth) acrylate (a), the unsaturated resin (B), and the ethylenically unsaturated compound (C).

The thickener is a compound showing a thickening effect, but does not include an inorganic filler, and isocyanate compounds can be exemplified. The thickener may be used alone or in combination of 2 or more.

The colorant is used when coloring of a molded article is required, and various inorganic pigments or organic pigments can be used. The amount of the colorant used may be appropriately adjusted according to the desired degree of coloration of the molded article.

Examples of the polymerization inhibitor include, but are not limited to, hydroquinone, trimethylhydroquinone, p-benzoquinone, naphthoquinone, t-butylhydroquinone, catechol, p-t-butylcatechol, and 2, 6-di-t-butyl-4-methylphenol.

The resin composition preferably does not contain inorganic fibers. Examples of the inorganic fibers include glass fibers, carbon fibers, and metal fibers. When the resin composition contains inorganic fibers, the object to be polished may be damaged by polishing when the cured product of the resin composition is used as a polishing pad.

Here, "not containing inorganic fibers" means that the content of inorganic fibers in the resin composition and the cured product thereof is 0.1% by mass or less, but it is not excluded that the inorganic fibers are mixed with other components such as impurities.

< 2. method for producing resin composition

The resin composition can be produced by mixing the urethane (meth) acrylate (a), the unsaturated resin (B), the ethylenically unsaturated compound (C), the hollow body (D), and additives added as needed. The mixing method includes, for example, kneading, and the kneading method is not particularly limited, and for example, a dispersing machine, a planetary mixer, a kneader, or the like can be used. The kneading temperature is preferably 5 to 40 ℃ and more preferably 10 to 30 ℃.

The mixing order of the components in the production of the resin composition is not particularly limited. For example, if a part or all of the urethane (meth) acrylate (a), the unsaturated resin (B), and the ethylenically unsaturated compound (C) are mixed and then mixed with other components, a resin composition in which the components are sufficiently dispersed or uniformly mixed can be easily obtained, which is preferable. At least a part of the ethylenically unsaturated compound (C) may be mixed in advance with the urethane (meth) acrylate (a) or the unsaturated resin (B) as a solvent, a dispersion medium, or the like.

< 3. method for producing polishing pad

The polishing pad can be produced by a step of molding and curing the resin composition and a step of grinding the surface of the cured resin composition.

The step of molding and curing the resin composition is not particularly limited, and examples thereof include a method of opening a mold and injecting the resin composition into the mold, a method of reducing the pressure in the mold, and a method of injecting the resin composition from the outside into a closed mold through a hole provided in the mold such as a slide valve (スプール) by applying a pressure from the outside of the mold, as typified by injection molding. The conditions for curing the resin composition in the mold may be set appropriately according to the material used, and one example of preferable conditions is a temperature of 10 to 40 ℃ and a curing time of 1 to 60 minutes. As another preferable condition, there is exemplified a condition that curing is carried out at a temperature of 10 to 40 ℃ for 1 to 4 hours and then re-curing is carried out at a temperature of 60 to 150 ℃ for 1 to 4 hours.

By the step of grinding the surface of the cured resin composition, the outer wall of the hollow body (D) present on the surface of the cured product of the resin composition is ground and flattened, and pores derived from the pores of the hollow body (D) are formed on the surface of the cured product of the resin composition. A flat grinder may be used in this process.

Regarding the hardness of the polishing pad, if the barcol hardness is 10 or more, the deformation of the polishing pad can be suppressed, and polishing sagging at the end of the object to be polished can be suppressed. From this viewpoint, the barcol hardness of the polishing pad is preferably 15 or more, and more preferably 20 or more. If the hardness of the polishing pad is 40 or less in terms of the barcol hardness, a locally concentrated load on the surface of the object to be polished due to the unevenness of the abrasive grain size can be suppressed during polishing by the CMP method. From this viewpoint, the barcol hardness of the polishing pad is preferably 33 or less, and more preferably 30 or less.

If the number of pores on the surface of the polishing pad is 13/mm²As described above, the load applied to the surface of the object to be polished can be dispersed, and the formation of scratches on the surface of the object to be polished can be suppressed. From such a viewpoint, it is preferable that the number of pores on the surface of the polishing pad is 30 pores/mm²Above, more preferably 45 pieces/mm²The above. If the number of pores on the surface of the polishing pad is 100/mm²The following, polishing padSufficient hardness can be ensured. From such a viewpoint, the number of pores on the surface of the polishing pad is preferably 80/mm²The number of the particles is preferably 70/mm or less²The following. The number of pores on the surface of the polishing pad is determined by, for example, counting the number of pores existing in a predetermined area range by a visual observation device such as a microscope, and dividing the counted number of pores by the area of the range to be counted.