JP3325562B1 - Method for producing foamed polyurethane polishing pad - Google Patents

Abstract

A method for manufacturing a polishing pad having a polishing layer of foamed polyurethane and having stable polishing characteristics is provided. Production of a polishing pad having a polishing pad which does not contain a material for forming a concave portion on a polishing surface such as water-soluble resin fine particles or hollow fine particles, or polystyrene foam beads, etc. Provide a way. SOLUTION: A silicon-based surfactant is added to an isocyanate-terminated prepolymer, and a stirring step is performed in the presence of a non-reactive gas to form a foam dispersion, and a chain extender is added to the foam dispersion and mixed. A foaming reaction liquid, a curing step of reacting and curing the foaming reaction liquid, wherein the isocyanate monomer content of the isocyanate-terminated prepolymer is 2
A method for producing a foamed polyurethane polishing pad of 0% by weight or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to optical materials such as lenses and reflecting mirrors, silicon wafers, glass substrates for hard disks, aluminum substrates, and materials requiring high surface flatness such as general metal polishing. The present invention relates to a polishing pad capable of performing a flattening process stably with high polishing efficiency. The polishing pad of the present invention is used particularly in a step of flattening a silicon wafer and a device having an oxide layer, a metal layer, etc. formed thereon, before laminating and forming these oxide layers and metal layers. It is also possible.

[0002]

2. Description of the Related Art Semiconductor integrated circuits (ICs, LSIs) are typically used as materials requiring high surface flatness.
And a single-crystal silicon disk called a silicon wafer. Silicon wafer, IC, LS
In a manufacturing process such as I, in order to form a reliable semiconductor junction of various thin films used for forming a circuit, it is required to finish the surface with high precision and flatness in each process. In such a polishing finishing step, a polishing pad is generally fixed to a rotatable support disk called a platen, and a workpiece such as a semiconductor wafer is fixed to a polishing head. By both movements, a relative speed is generated between the platen and the polishing head, and a polishing operation is performed by continuously supplying a polishing slurry containing abrasive grains onto the polishing pad.

A polishing pad used for such a CMP process is disclosed in Japanese Patent No. 3013105,
The technology described in 1-322878 is known. The technique disclosed in Japanese Patent No. 3013105 is a polishing pad in which fine particles or hollow fine particles of a water-soluble resin are added to a polymer matrix such as a polyurethane polymer. The technique disclosed in JP-A-11-322878 is a polishing pad in which polystyrene foam beads are dispersed in a polyurethane polymer.

[0004]

However, in the above-mentioned known polishing pad, when water-soluble resin fine particles or hollow fine particles, or polystyrene foam beads are dispersed in the resin, the density of the polyurethane resin as a matrix resin is reduced. The dispersion particles are likely to be non-uniform due to the difference between them.
The fine particles or hollow fine particles in the above-mentioned known technology are CM
In P processing, a small concave portion is formed on the polishing surface of the polishing pad to exert an important function of retaining the polishing abrasive grains. Such unevenness of the dispersed fine particles greatly affects the performance of the polishing pad.

On the other hand, when a foamed polyurethane polishing pad obtained by reacting and curing an isocyanate group-containing compound and a compound containing an active hydrogen group is used, sufficient polishing performance cannot be obtained even when similar components are used. May be
Improvement is required.

An object of the present invention is to provide a method for producing a polishing pad having a polishing layer composed of foamed polyurethane and having stable polishing characteristics. Another object of the present invention is to provide a polishing pad which does not include a material for forming a concave portion on a polishing surface, such as fine particles or hollow fine particles of a water-soluble resin, or polystyrene foam beads, and in which pores are formed only of polyurethane. An object of the present invention is to provide a method for manufacturing a polishing pad having:

[0007]

DISCLOSURE OF THE INVENTION The present inventors have found that when an isocyanate group-terminated prepolymer is used as an isocyanate group-containing compound as a raw material of a polyurethane foam,
It has been found that by controlling the content of the isocyanate monomer in the isocyanate group-terminated prepolymer to a predetermined value or less, abrasion resistance during polishing is good and a polishing pad having excellent polishing characteristics can be obtained. Completed the invention.

That is, the present invention relates to a method for producing a foamed polyurethane polishing pad, which comprises adding a silicone-based surfactant to an isocyanate-terminated prepolymer and stirring the mixture in the presence of a non-reactive gas to form a foam dispersion. A step of adding a chain extender to the foam dispersion liquid and mixing the resulting mixture to form a foaming reaction liquid, and a curing step of reacting and curing the foaming reaction liquid, wherein the isocyanate monomer content of the isocyanate-terminated prepolymer is reduced. It is not more than 20% by weight.

It is not clear why the use of a prepolymer having an isocyanate monomer content of 20% by weight or less improves the polishing characteristics. However, if the isocyanate monomer content exceeds 20%, the chain extender and the isocyanate monomer are not improved. It is also presumed that one cause is that the reaction proceeds first and the polyurethane does not sufficiently increase the molecular weight.

The foamed polyurethane obtained is one in which fine bubbles are formed without adding a material for forming a concave portion on the polishing surface such as water-soluble resin fine particles or hollow fine particles, or polystyrene foam beads. Since the presence of the fine bubbles allows the abrasive grains in the slurry to be retained on the pad surface during the polishing operation, a satisfactory polishing rate can be obtained. The fine cells of foamed polyurethane are
The average bubble diameter (cell diameter) is 70 μm or less, preferably 50 μm or less, and more preferably 40 μm or less. Generally, the thickness is preferably 30 to 40 μm.

In the above invention, the isocyanate-terminated prepolymer is obtained by using at least one of aliphatic diisocyanate and alicyclic diisocyanate (first isocyanate component) and aromatic diisocyanate (second isocyanate component) as isocyanate components. Wherein the ratio in the isocyanate monomer is such that the first isocyanate component / the second isocyanate component = 0.5 to
It is preferably 3.2 (weight ratio).

By using an aliphatic diisocyanate or an alicyclic diisocyanate, which has a relatively slow reaction, and an aromatic diisocyanate as a diisocyanate component constituting the isocyanate-terminated prepolymer, good polishing characteristics can be obtained, and mixing with a chain extender can be achieved. The resulting cured polyurethane has an appropriate curing time and is easy to produce.

The first isocyanate component is 4,4'-
Dicyclohexylmethane diisocyanate, and the second isocyanate component is preferably toluene diisocyanate.

By using such an isocyanate component,
A foamed polyurethane having excellent physical properties of a resin constituting the foamed polyurethane and particularly excellent polishing properties can be obtained.

When the weight ratio of the first isocyanate component / the second isocyanate component in the isocyanate monomer in the isocyanate-terminated prepolymer is less than 0.5, the curing time is short, and stable molding of a polyurethane foam or a polishing pad cannot be performed. . On the other hand, when the weight ratio of the first isocyanate component / the second isocyanate component exceeds 3.2, it takes a long time to complete the curing step of reacting and curing the isocyanate-terminated prepolymer and the chain extender, leading to an increase in cost, which is not preferable. .

In the method for producing a foamed polyurethane polishing pad of the present invention, the amount of the silicone surfactant added in the stirring step is 0.05 to 5% by weight in the polyurethane.
It is preferable that

In the production of foamed polyurethane, it is advantageous to mix a silicone-based surfactant in advance with the polyurethane raw material in order to stably produce fine air bubbles, and to make the air bubbles uniform without impairing the physical properties of the polyurethane. A stable polyurethane foam can be obtained.

When the amount of the silicon-based surfactant added is 0.1.
If the amount is less than 05% by weight, a foam having fine cells may not be obtained. On the other hand, when the addition amount exceeds 5% by weight, the number of cells (cells) in the polyurethane foam increases, and it is difficult to obtain a polyurethane microcellular foam having high hardness. In addition, the action of the silicone-based surfactant, which is presumed to be plasticization of the polyurethane, lowers the strength of the polishing pad and lowers the polishing characteristics.

In the above-described method for manufacturing a polishing pad,
It is preferable that the polishing pad further includes a laminating step of laminating a flexible porous sheet on the polishing pad.

By providing a flexible porous sheet as a cushion layer, a polishing pad having more excellent flattening characteristics can be obtained.

[0021]

DETAILED DESCRIPTION OF THE INVENTION The polyurethane constituting the polishing pad of the present invention comprises an organic polyisocyanate, a polyol compound and a chain extender.

As the organic polyisocyanate, a compound known in the field of polyurethane can be used without particular limitation. Examples of the organic polyisocyanate include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 2,2′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate,
4,4'-diphenylmethane diisocyanate, 1,5
Aromatic diisocyanates such as naphthalene diisocyanate, p-phenylene diisocyanate, m-phenylene diisocyanate, p-xylylene diisocyanate, m-xylylene diisocyanate, ethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 1,6- Examples include aliphatic diisocyanates such as hexamethylene diisocyanate, and alicyclic diisocyanates such as 1,4-cyclohexane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate, and norbornane diisocyanate. Even if these are used alone,
Two or more kinds may be mixed.

As the organic polyisocyanate, a trifunctional or higher polyfunctional polyisocyanate compound can be used in addition to the above diisocyanate compound. As polyfunctional isocyanate compounds, a series of diisocyanate adduct compounds are commercially available as Desmodur-N (manufactured by Bayer AG) or trade name duranate (manufactured by Asahi Kasei Corporation).

Among the above diisocyanates, it is preferable to use 4,4'-dicyclohexylmethane diisocyanate (hydrogenated MDI = HMDI) and toluene diisocyanate in combination as described above. Toluene diisocyanate is 2,4-toluene diisocyanate / 2,
6-toluene diisocyanate = 100/0 to 60/4
It is preferably 0 (molar ratio) in view of the characteristics of the polyurethane foam.

Examples of the polyol compound include those commonly used as a polyol compound in the technical field of polyurethane. For example, hydroxy-terminated polyester, polycarbonate, polyester carbonate, polyether, polyether carbonate,
In the technical field of polyurethane such as polyesteramide, compounds known as polyols may be mentioned. Of these, use of polyether and polycarbonate having good hydrolysis resistance is preferable, and they are more inexpensive and have a lower melt viscosity. Polyether is particularly preferred from the viewpoint that the reaction is easy.

Examples of polyether polyols include polytetramethylene glycol (PTMG), polypropylene glycol (PPG), and polyethylene glycol (PE
G) and the like. Among them, PTMG is more preferably used because a polishing pad having excellent polishing characteristics can be obtained.

Examples of the polyester polyol include polybutylene adipate, polyhexamethylene adipate, and polycaprolactone polyol.

As the polyester polycarbonate polyol, a reaction product of a polyester glycol such as a polycaprolactone polyol and an alkylene carbonate, and ethylene carbonate as a polyvalent alcohol. A reaction product obtained by reacting the obtained reaction mixture with an organic dicarboxylic acid is exemplified.

Examples of the polycarbonate polyol include 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, polyethylene glycol, polypropylene glycol and / or polytetramethylene glycol. And the like, and phosgene, a diallyl carbonate (eg, diphenyl carbonate) or a cyclic carbonate (eg, propylene carbonate).

In the production of polyurethane foam having fine cells constituting the polishing layer, the above polyols may be used alone or in combination of two or more. If necessary, three or more functional components may be used in combination.

The number average molecular weight of these polyols is not particularly limited, but is preferably from 500 to 5,000, more preferably from 700 to 3,000, from the viewpoint of the elastic properties of the obtained polyurethane foam. preferable.

When the number average molecular weight of the polyol is less than 500, the polyurethane foam obtained by using the polyol does not have sufficient elasticity properties and easily becomes a brittle polymer. It may become too hard and cause scratches on the polished surface of the workpiece to be polished. Further, the abrasive pad is easily worn, which is not preferable from the viewpoint of the life of the polishing pad.

On the other hand, when the number average molecular weight exceeds 5,000, the polishing pad having a polyurethane foam as a matrix obtained by using the same becomes soft, and sufficient polishing characteristics cannot be obtained.

The constituent components of the foamed polyurethane include, in addition to the above-mentioned polyols, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol. Low molecular weight polyhydric alcohols such as neopentyl glycol, 1,4-cyclohexanedimethanol, 3-methyl-1,5-pentanediol, diethylene glycol, triethylene glycol, and 1,4-bis (2-hydroxyethoxy) benzene. You may use them together. These low molecular weight polyhydric alcohols may be used alone or in combination of two or more.

In the present invention, the chain extender which reacts with the isocyanate-terminated prepolymer to increase the molecular weight is an organic compound having at least two or more active hydrogen groups,
Examples of the active hydrogen group include a hydroxyl group, a primary or secondary amino group, and a thiol group (SH). Specifically, 4,4′-methylenebis (o-chloroaniline),
2,6-dichloro-p-phenylenediamine, 4,4 '
-Methylenebis (2,3-dichloroaniline), 3,5
-Bis (methylthio) -2,4-toluenediamine,
3,5-bis (methylthio) -2,6-toluenediamine, 3,5-diethyltoluene-2,4-diamine,
3,5-diethyltoluene-2,6-diamine, trimethylene glycol-di-p-aminobenzoate, 1,
2-bis (2-aminophenylthio) ethane, 4,4 ′
Examples thereof include polyamines exemplified by -diamino-3,3'-diethyl-5,5'-dimethyldiphenylmethane and the like, and low-molecular-weight polyols described above. These may be used alone or in combination of two or more.

An organic polyisocyanate according to the present invention,
The ratio of the polyol compound and the chain extender can be variously changed depending on the molecular weight of each and the desired physical properties of the polishing pad. In order to obtain a polishing pad having desired polishing characteristics, the number of isocyanate groups of the organic polyisocyanate with respect to the total number of active hydrogen groups (hydroxyl group + amino group) of the polyol compound and the chain extender is in the range of 0.95 to 1.15. And more preferably 0.99 to 1.10.

The ratio between the polyol and the low-molecular-weight polyhydric alcohol is appropriately set according to the characteristics required for the polyurethane produced therefrom.

The production of foamed polyurethane is based on a so-called prepolymer method, that is, a production method in which an isocyanate-terminated prepolymer is previously synthesized from an organic polyisocyanate and a polyol compound, and the prepolymer is reacted with a chain extender.

Although isocyanate-terminated prepolymers produced from an organic polyisocyanate and a polyol compound are commercially available, they can be used in the present invention by the prepolymer method if they are compatible with the present invention. It is also possible to polymerize polyurethane. The isocyanate-terminated prepolymer has a molecular weight of 800 to 50.
Those having a value of about 00 are preferable because they have excellent workability and physical properties.

The isocyanate-terminated prepolymer is 2
More than one kind may be used as a mixture.Especially, in the production of a foamed polyurethane using an aliphatic or alicyclic diisocyanate and an aromatic diisocyanate, a prepolymer using an aliphatic or alicyclic diisocyanate may be used. Mixing a prepolymer using an aromatic diisocyanate is a preferred embodiment.

As a method for adjusting the residual ratio of the isocyanate monomer, for example, a prepolymer having a small residual ratio of the isocyanate monomer may be prepared and the isocyanate monomer may be added to the prepolymer. Distillation from prepolymer,
The isocyanate monomer may be removed under reduced pressure or the like.

The method for manufacturing the polishing pad of the present invention will be described. The method for manufacturing a polishing pad includes the following steps. (1) Stirring step for preparing an isocyanate-terminated prepolymer foam dispersion liquid A silicon-based surfactant is added to the isocyanate-terminated prepolymer, stirred with a non-reactive gas, and the non-reactive gas is dispersed as fine bubbles to form bubbles. Make it a dispersion. When the prepolymer is solid at room temperature, it is preheated to an appropriate temperature and melted before use. (2) Hardener (chain extender) mixing step A chain extender is added to the above-mentioned foam dispersion liquid, and mixed and stirred to obtain a foaming reaction liquid. When the chain extender is a compound that is solid at room temperature, it is preferable to add it by melting. (3) Curing Step A foaming reaction solution of an isocyanate-terminated prepolymer mixed with a chain extender is poured into a predetermined mold and cured by heating.

When it is formed into a block shape upon curing, it is cut into a sheet having a predetermined thickness and a predetermined size in a cutting step.

The sheet-like foamed polyurethane is provided with a laminating step of forming a cushion layer by attaching a flexible porous sheet or the like before or after cutting to the size of the polishing pad, if necessary. A polishing pad having a layer structure is manufactured.

As the stirring device for converting the non-reactive gas into fine bubbles in the stirring step and dispersing it in the isocyanate-terminated prepolymer containing the silicone-based surfactant, a known stirring device can be used without any particular limitation. Examples thereof include a homogenizer, a dissolver, and a twin-screw planetary mixer (planetary mixer). The shape of the stirring blade of the stirring device is not particularly limited, but the use of a whipper-type stirring blade is preferable because fine bubbles can be obtained.

It is a preferable embodiment that different stirring devices are used for the stirring for preparing the cell dispersion in the stirring step and the stirring for adding and mixing the chain extender in the mixing step. In particular, the stirring in the mixing step need not be stirring to form bubbles, and it is preferable to use a stirring device that does not involve large bubbles. As such a stirring device,
Planetary mixers are preferred. There is no problem even if the same stirring device is used as the stirring device in the stirring process and the mixing process, and it is also preferable to use the stirring device by adjusting the stirring conditions such as adjusting the rotation speed of the stirring blade as necessary. .

As the silicon-based surfactant used in the present invention, those which stably form fine bubbles without reacting with the polyurethane raw material can be used without limitation, but the physical properties of the polyurethane are not impaired. From the viewpoint of stably producing uniform fine bubbles, a silicon-based surfactant is preferable. In particular, a surfactant of a copolymer of silicon (polyalkylsiloxane) and polyether is preferable. Here, examples of the polyether include polyethylene oxide, polypropylene oxide, and copolymers thereof. It is also preferable that the terminal of the polyether of the copolymer is a group which is inert to an isocyanate group such as an alkyl ether such as methyl ether or an acetyl group. As such a silicon-based surfactant, a commercially available product can be used. For example, SH-192 and SH-193 can be used.
(Manufactured by Dow Corning Toray Silicone Co., Ltd.) and the like are exemplified.

The non-reactive gas used in producing the foamed polyurethane is a gas composed only of a normal-temperature gas component that does not react with isocyanate groups or active hydrogen groups. The gas may be actively fed into the liquid, or only the situation where the gas is naturally entrained during the stirring may be used. The non-reactive gas used to form the microbubbles is preferably a non-flammable gas. Specific examples include nitrogen, oxygen, carbon dioxide, rare gases such as helium and argon, and mixtures thereof. Air that has been dried to remove moisture is most preferable in terms of cost.

In the present invention, a stabilizer such as an antioxidant, a lubricant, a pigment, a filler, an antistatic agent and other additives may be added to the polyurethane composition, if necessary. .

The method for producing the polishing pad of the present invention includes:
First, a mixed solution obtained by mixing a polyurethane raw material is injected into a mold, and then reacted and cured until it no longer flows to prepare a polyurethane block. In the case of foaming polyurethane, foaming is performed together with curing. The obtained foamed polyurethane block can be heated and post-cured,
Such an operation has an effect of improving the physical properties of the polyurethane, and is extremely suitable. In the production of polyurethane foam,
A known catalyst for promoting the polyurethane reaction may be used. The type and amount of the catalyst are appropriately selected.

Next, the obtained polyurethane foam block is sliced to a thickness suitable for a polishing pad (polishing layer). The thickness of the polishing pad is about 0.8 mm to 2 mm, and a sheet having a thickness of about 1.2 mm is usually used. In addition to this method, the polyurethane component may be poured into a mold having a cavity having the same thickness as the intended thickness of the polishing pad.

A polishing pad can be formed by forming grooves on the surface of the polishing pad or attaching a flexible porous sheet or the like to the back surface. The grooves on the surface of the polishing pad have a function of allowing polishing debris and abrasive to escape from the contact surface between the workpiece and the polishing sheet. Although the shape of the groove is not particularly limited, the cross section is exemplified by a rectangle, a triangle, a U-shape, a semicircle, or the like, and may have a cross-sectional area through which the fine powder passes. The grooves are arranged on the sheet surface in a concentric shape, a lattice shape, or the like. The depth of the groove depends on the thickness of the sheet and the like.
mm.

As the flexible porous sheet laminated on the back surface, a fibrous nonwoven fabric layer such as a polyester nonwoven fabric, a nylon nonwoven fabric, and an acrylic nonwoven fabric, or a material obtained by impregnating the nonwoven fabric with a urethane resin, a urethane resin, a polyethylene resin, or the like is used. Closed cell foams and the like can be exemplified. Among these, urethane-impregnated polyester nonwoven fabric, polyurethane foam or polyethylene foam is preferred in terms of ease of production, low cost, stability of physical properties, etc., and polyurethane closed cell foam is particularly preferred.

[0054]

Hereinafter, the present invention will be described with reference to examples.
The present invention is not limited to these examples.

[Evaluation Method] (Polishing Characteristics) The polishing characteristics of the polishing pad were evaluated using a CMP polishing apparatus SPP-600S (manufactured by Okamoto Machine Tool Co., Ltd.). The polishing conditions were as follows: as a slurry, a ceria slurry adjusted to pH 8 (Nissan Chemical Co., Ltd. ceria sol) was used.
Polishing load 350 g / cm while flowing at a flow rate of 0 g / min.
^2. Polishing pad rotation speed 35rpm, wafer rotation speed 33r
pm. The polishing characteristics were evaluated based on the average polishing rate. Those having a polishing rate of 2000 ° / min or more were evaluated as polishing characteristics ○, and those having a polishing rate of less than 2000 ° / min were evaluated as polishing characteristics X.

(Remaining monomer ratio) A 10 mg isocyanate-terminated prepolymer sample inactivated by reacting the terminal isocyanate group with methanol was added to 10 ml of TH.
F, and the residual monomer ratio was determined from the peak area of the methanol reactant of the isocyanate monomer using a GPC measuring device LC10A (manufactured by Shimadzu Corporation). The measurement was carried out using a Plgel column (filler particle size 5 μm, pore size 50
0/100 / 50Å), and the sample solution was
l, using THF as solvent, flow rate 1 ml / m
Measured in.

(Pot life) The isocyanate-terminated prepolymer was heated to 60 ° C., and molten 4,4′-methylenebis (o-chloroaniline) adjusted to 120 ° C. was added to NC.
The mixture is added and mixed so that the O group / OH group equivalent ratio becomes 1.1, and the mixture is cast on a glass plate heated to 50 ° C. so as to have a thickness of about 5 mm. This liquid film is pierced three times with a square bar (about 3 mm square), and the surface is observed for 10 seconds. The time during which the fluidity of the liquid was lost and the irregularities formed by piercing the square bar remained even after 10 seconds was defined as the pot life.

(Evaluation of Formability) In the following example of the production of a polishing pad material, the curable foaming composition was poured into a pan-shaped open mold and molded. The case where the resin did not completely spread in the mold was evaluated as moldability evaluation x.

(Examples 1 to 5, Comparative Examples 1 to 6) <Production of polishing pad material> Polytetramethylene glycol (hereinafter abbreviated as PTMG) having a number average molecular weight of 1000 and diethylene glycol (hereinafter abbreviated as DEG). ) Were mixed at PTMG / DEG = 50/50 (molar ratio) as a glycol component, and the glycol component and toluene diisocyanate (2,4-form / 2,6-
80/20 mixture: hereinafter, abbreviated as TDI), is used in excess so that the TDI monomer after the reaction has a predetermined amount, and is heated and stirred at 80 ° C. for 120 minutes, and then distilled under reduced pressure to obtain an isocyanate monomer. Was removed to produce an isocyanate-terminated TDI prepolymer. Further, using the same glycol component, 4,4′-dicyclohexylmethane diisocyanate (hereinafter abbreviated as HMDI) is used.
The HMDI monomer after the reaction was used in excess so as to be a predetermined amount, heated and stirred at 80 ° C. for 120 minutes, and then distilled under reduced pressure to remove the isocyanate monomer to prepare an isocyanate-terminated HMDI prepolymer.

The above two prepolymers are mixed so that the weight ratio of TDI prepolymer / HMDI prepolymer is 75/25, and each isocyanate monomer is added so that each isocyanate monomer becomes a predetermined amount. As a raw material prepolymer for producing polyurethane foam.

A predetermined amount of a silicone surfactant SH-192 (manufactured by Toray Dow Corning Silicone Co., Ltd.) was added to 100 parts by weight of the obtained raw material prepolymer, mixed and adjusted to 80 ° C., and then a whipper type stirring blade was used. The mixture was stirred vigorously so as to take in bubbles using a mixer having a bubble dispersion. Change stirrer to planetary mixer,
To this foam dispersion, 4,4′-methylenebis (o-chloroaniline) (hereinafter abbreviated as MOCA) previously melted at 120 ° C. was added at an NCO / NH ₂ equivalent ratio of 1.
1 and stirred for about 1 minute. The obtained curable foaming composition was placed in a pan-shaped open mold, and post-cured in an oven at 110 ° C. for 6 hours to produce a foamed polyurethane block. The cellular system of this foamed polyurethane is approximately 40 to 50 μm, and the density is 0.85.
０．９0.90 g / cm ³ .

The residual ratio of the isocyanate monomer in the prepolymer and the HMDI monomer / TDI monomer ratio of the residual monomer are shown in the upper part of Table 1.

<Preparation of Polishing Pad> While the obtained foamed polyurethane block of fine cells, which is a constituent material of the polishing pad, was heated to about 50 ° C., it was sliced to a thickness of 2 mm with a slicer (VGW-125 manufactured by Amitec). Then, a foamed polyurethane sheet was obtained. This sheet has a diameter of 610
mm, and cut into a grid on the sheet surface (groove width 2.
0mm, groove depth 0.6mm, groove pitch 1.5mm), concentric (groove width 0.3mm, groove depth 0.4mm, groove pitch 1.5mm) Each of them was produced. A cushioning material for a commercially available polishing pad was adhered to the grooved foamed polyurethane sheet with a double-sided tape to complete a polishing pad sample. The polishing rate was measured using the obtained polishing pad, and the evaluation results are shown in Table 1.

[0064]

[Table 1] As is clear from Table 1, the polishing pad of the present invention showed good results in all evaluations. On the other hand, in Comparative Examples 1 and 2 in which the residual ratio of isocyanate monomer exceeds 20 wt%, the polishing characteristics were not satisfactory, and even when the residual ratio of isocyanate monomer was 20 wt% or less, the HMDI / TDI weight ratio of the residual monomer was 3%. In Comparative Examples 3 and 4 exceeding 0.2, the curing was slow and the moldability was not satisfactory. In Comparative Example 5 in which the HMDI / TDI weight ratio was less than 0.5, the pot life was too short to perform molding.
Comparative Example 6, in which the addition amount of the silicon surfactant exceeds 5 wt%, shows that the isocyanate monomer residual ratio,
Both the HMDI / TDI weight ratio was within the range of the present invention, but the polishing characteristics were not satisfactory.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI // (C08G 18/10 (C08G 18/10 101: 00) 101: 00) (72) Inventor Takeshi Kimura Nishi-ku, Osaka-shi, Osaka Edobori 1-1-17-18 Toyo Tire & Rubber Co., Ltd. (72) Inventor Koichi Ono 2-1-1 Katata, Otsu-shi, Shiga Prefecture Toyo Spinning Co., Ltd. 2-1-1, Toyobo Co., Ltd. Research Institute (72) Inventor Tetsuo Shimomura 2-1-1 Katata, Otsu-shi, Shiga Prefecture Toyo Spinning Co., Ltd. Research Institute (56) References JP 2001-89548 (JP) JP-A-1-222868 (JP, A) JP-A-4-115875 (JP, A) JP-A-2000-344850 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) ) C08G 18/00-18/87 B24B 37/00 C08J 5/1 4 C09K 3/14 H01L 21/304

Claims (4)

(57) [Claims] 1. A method for producing a foamed polyurethane polishing pad, comprising the steps of: adding a silicon-based surfactant to an isocyanate-terminated prepolymer; and stirring in the presence of a non-reactive gas to form a foam dispersion. A mixing step of adding a chain extender to the foam dispersion and mixing the mixture to form a foaming reaction liquid; and a curing step of reacting and curing the foaming reaction liquid. The isocyanate monomer content of the isocyanate-terminated prepolymer is 20% by weight. The following is a method for producing a foamed polyurethane polishing pad. 2. The isocyanate-terminated prepolymer uses at least one of aliphatic diisocyanate and alicyclic diisocyanate (first isocyanate component) and aromatic diisocyanate (second isocyanate component) as isocyanate components, The ratio of the first isocyanate component / the second isocyanate component in the isocyanate monomer is 0.5 to 3.2 (weight ratio).
The method for producing a foamed polyurethane polishing pad according to claim 1, wherein 3. The method according to claim 1, wherein the first isocyanate component is 4,4 ′.
The method for producing a foamed polyurethane polishing pad according to claim 2, wherein the polishing pad is dicyclohexylmethane diisocyanate, and the second isocyanate component is toluene diisocyanate. 4. The method for producing a foamed polyurethane polishing pad according to claim 1, wherein the amount of the silicon surfactant added in the stirring step is 0.05 to 5% by weight. .