JP4465376B2 - Polishing pad manufacturing method - Google Patents

Description

  The present invention relates to an optical material such as a lens and a reflection mirror, a silicon wafer, a glass substrate for a hard disk, and a polishing pad used when polishing the surface of an aluminum substrate and a method for manufacturing the same. In particular, the polishing pad of the present invention is suitably used as a polishing pad for finishing.

  In general, mirror polishing of a semiconductor wafer such as a silicon wafer includes rough polishing mainly for adjusting flatness and in-plane uniformity, and finish polishing mainly for improving surface roughness and removing scratches. is there.

  The finish polishing is usually performed by attaching a suede-like artificial leather made of soft urethane foam on a rotatable surface plate and supplying an abrasive containing colloidal silica to an alkali-based aqueous solution. (Patent Document 1).

  In addition to the above, the following polishing pads have been proposed as finish polishing pads used for finish polishing.

  A suede-like finish polishing pad consisting of a nap layer in which polyurethane foam is formed with a number of elongated fine holes (nap) formed in the thickness direction using a foaming agent and a base fabric that reinforces the nap layer has been proposed. (Patent Document 2).

  In addition, a polishing cloth for finish polishing that is suede-like and has a surface roughness of 5 μm or less in arithmetic mean roughness (Ra) has been proposed (Patent Document 3).

  Also, a polishing cloth for finishing polishing comprising a base material part and a surface layer (nap layer) formed on the base material part, wherein the surface layer contains a polyvinyl halide or a vinyl halide copolymer. Has been proposed (Patent Document 4).

  Conventional polishing pads for finishing have been manufactured by a so-called wet curing method. The wet curing method is a method in which a urethane resin solution in which a urethane resin is dissolved in a water-soluble organic solvent such as dimethylformamide is applied onto a substrate, which is treated in water and wet solidified to form a porous silver surface layer. The surface layer (nap layer) is formed by grinding the surface of the silver surface layer after washing and drying. For example, in Patent Document 5, a polishing pad for finishing having a substantially spherical hole with an average diameter of 1 to 30 μm is manufactured by a wet curing method.

  However, the wet curing method has a problem that it is necessary to use a large amount of pure water which does not contain metal impurities, requires a large amount of capital investment, and has a very high manufacturing cost. In addition, there is a problem that the environmental load is large because a solvent must be used. Further, the conventional polishing pad for finishing has a problem that the durability of the bubbles is poor and the stability of the polishing rate is inferior because the bubbles have an elongated structure. On the other hand, in the polishing cloth for finishing of Patent Document 5, since the bubbles are substantially spherical, durability and stability of the polishing rate are improved as compared with the conventional ones, but the raw material is thermoplastic polyurethane. There was a problem of lowering durability.

JP 2003-37089 A JP 2003-1000068 A1 JP 2004-291155 A JP 2004-335713 A JP 2006-75914 A

  An object of the present invention is to provide a method for easily and inexpensively manufacturing a polishing pad excellent in durability and stability of polishing rate.

  As a result of intensive studies to solve the above problems, the present inventors have found that the above object can be achieved by the manufacturing method shown below, and have completed the present invention.

That is, the present invention includes a step of preparing a cell-dispersed urethane composition by a mechanical foaming method, a step of applying a cell-dispersed urethane composition on a base material layer, and curing the cell-dispersed urethane composition to form a substantially spherical open cell. I saw including a step of forming a polyurethane foam layer, and a step of uniformly regulating the thickness of the polyurethane foam layer having,
The cell-dispersed urethane composition contains an isocyanate component and an active hydrogen-containing compound, and the active hydrogen-containing compound contains 60 to 85% by weight of a high molecular weight polyol having a hydroxyl value of 20 to 100 mgKOH / g and a hydroxyl value of 400. ~1830mgKOH / g low molecular weight polyol to a method of manufacturing a 2 to 15% by weight including the polishing pad, related.

Another aspect of the present invention is a step of preparing a cell-dispersed urethane composition by a mechanical foaming method, a step of applying a cell-dispersed urethane composition on a base material layer, and laminating a release sheet on the cell-dispersed urethane composition. A step of curing the cell-dispersed urethane composition with a uniform thickness by pressing means to form a polyurethane foam layer having substantially spherical open cells, and a step of peeling the release sheet on the polyurethane foam layer. See
The cell-dispersed urethane composition contains an isocyanate component and an active hydrogen-containing compound, and the active hydrogen-containing compound contains 60 to 85% by weight of a high molecular weight polyol having a hydroxyl value of 20 to 100 mgKOH / g and a hydroxyl value of 400. ~1830mgKOH / g low molecular weight polyol to a method of manufacturing a 2 to 15% by weight including the polishing pad, related.

  As described above, a gas-dispersed urethane composition is prepared by dispersing a gas such as air as fine bubbles in a raw material by a mechanical foaming method (including a mechanical froth method) and curing the cell-dispersed urethane composition. A polyurethane foam layer (polishing layer) having substantially spherical (spherical and elliptical) open cells can be formed very easily. Further, in the mechanical foaming method of the present invention, since gas such as air is dispersed without being dissolved in the raw material, new bubbles are generated after the step of uniformly adjusting the thickness of the polyurethane foam layer ( There is an advantage that the post-foaming phenomenon) can be suppressed and the thickness accuracy and specific gravity can be easily controlled. Further, since it is not necessary to use a foaming agent such as a solvent or chlorofluorocarbon, it is not only excellent in cost but also preferable from the environmental viewpoint. The polyurethane foam layer has excellent durability because it has substantially spherical cells. Therefore, when the material to be polished is polished using the polishing pad having the foam layer, the stability of the polishing rate is improved.

In the polishing pad provided with the polyurethane foam layer on the base material layer, the polyurethane foam layer is made of a thermosetting polyurethane foam having substantially spherical open cells, and the base material layer The thermosetting polyurethane foam is a reaction cured product of a cell-dispersed urethane composition containing an isocyanate component and an active hydrogen-containing compound, and the active hydrogen-containing compound has a hydroxyl value of 20 to 60 to 85% by weight of a high molecular weight polyol of 100 mg KOH / g and 2 to 15% by weight of a low molecular weight polyol having a hydroxyl value of 400 to 1830 mg KOH / g, the base layer is made of nylon, polyethylene, polypropylene, polyester, and non-foamed plastic off comprising at least one resin selected from the group consisting of polyvinyl chloride Polishing pad, which is a Lum relates.

  The average cell diameter of the thermosetting polyurethane foam is preferably 35 to 300 μm.

  The cell-dispersed urethane composition of the present invention is not particularly limited as long as it is prepared by a mechanical foaming method (including a mechanical floss method). For example, the cell-dispersed urethane composition is prepared by the following method.

  (1) The first component obtained by adding a silicon surfactant to an isocyanate-terminated prepolymer obtained by reacting an isocyanate component and a high molecular weight polyol is mechanically stirred in the presence of a non-reactive gas, and the non-reactive gas is removed. Disperse as fine bubbles to obtain a cell dispersion. Then, a second component containing an active hydrogen-containing compound such as a high molecular weight polyol or a low molecular weight polyol is added to the cell dispersion and mixed to prepare a cell dispersed urethane composition. A filler such as a catalyst and carbon black may be appropriately added to the second component.

  (2) A component in which a silicon-based surfactant is added to at least one of a first component containing an isocyanate component (or an isocyanate-terminated prepolymer) and a second component containing an active hydrogen-containing compound, and a silicon-based surfactant is added Is mechanically stirred in the presence of a non-reactive gas to disperse the non-reactive gas as fine bubbles to obtain a bubble dispersion. Then, the remaining components are added to the cell dispersion and mixed to prepare a cell-dispersed urethane composition.

  (3) A silicon-based surfactant is added to at least one of the first component containing the isocyanate component (or isocyanate-terminated prepolymer) and the second component containing the active hydrogen-containing compound, and the first component and the second component are added. A foam-dispersed urethane composition is prepared by mechanically stirring in the presence of a non-reactive gas and dispersing the non-reactive gas as fine bubbles.

  Thermosetting polyurethane is preferable as a material for forming the polishing layer because it can easily form substantially spherical fine bubbles by a mechanical foaming method.

  The cell dispersed urethane composition may be prepared by a mechanical floss method. The mechanical floss method is a method in which raw material components are put into a mixing chamber of a mixing head and a non-reactive gas is mixed and mixed and stirred by a mixer such as an Oaks mixer to make the non-reactive gas into a fine bubble state in the raw material mixture. It is a method of dispersing in. The mechanical floss method is a preferable method because the density of the polyurethane foam can be easily adjusted by adjusting the amount of the non-reactive gas mixed therein. Moreover, since the polyurethane foam layer which has a fine bubble with an average cell diameter of 35-300 micrometers can be continuously shape | molded, manufacturing efficiency is good.

  As the isocyanate component, a known compound in the field of polyurethane can be used without particular limitation. For example, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 2,2′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, 4,4′-diphenylmethane diisocyanate, polymeric MDI, carbodiimide-modified MDI (for example, commercial products) Name Millionate MTL, manufactured by Nippon Polyurethane Industry), 1,5-naphthalene diisocyanate, p-phenylene diisocyanate, m-phenylene diisocyanate, p-xylylene diisocyanate, m-xylylene diisocyanate, and other aromatic diisocyanates, ethylene diisocyanate, 2,2 1,4-trimethylhexamethylene diisocyanate, aliphatic diisocyanates such as 1,6-hexamethylene diisocyanate, 1,4-cyclohexane San diisocyanate, cyclohexane diisocyanate, 4,4'-dicyclohexyl methane diisocyanate, isophorone diisocyanate, and cycloaliphatic diisocyanates such as norbornane diisocyanate. These may be used alone or in combination of two or more.

  As the isocyanate component, a trifunctional or higher polyfunctional polyisocyanate compound can be used in addition to the diisocyanate compound. As a polyfunctional isocyanate compound, a series of diisocyanate adduct compounds are commercially available as Desmodur-N (manufactured by Bayer) or trade name Duranate (manufactured by Asahi Kasei Kogyo Co., Ltd.).

  Of the above isocyanate components, 4,4'-diphenylmethane diisocyanate or carbodiimide-modified MDI is preferably used.

  Examples of the high molecular weight polyol include those usually used in the technical field of polyurethane. Examples include polyether polyols typified by polytetramethylene ether glycol, polyethylene glycol, etc., polyester polyols typified by polybutylene adipate, polycaprolactone polyols, reactants of polyester glycols such as polycaprolactone and alkylene carbonate, etc. Polyester polycarbonate polyol obtained by reacting ethylene carbonate with polyhydric alcohol and then reacting the obtained reaction mixture with organic dicarboxylic acid, polycarbonate polyol obtained by transesterification of polyhydroxyl compound and aryl carbonate And polymer polyol which is a polyether polyol in which polymer particles are dispersed.These may be used alone or in combination of two or more.

  In order to make the polyurethane foam layer into an open-cell structure, it is preferable to use a polymer polyol, and it is particularly preferable to use a polymer polyol in which polymer particles made of acrylonitrile and / or a styrene-acrylonitrile copolymer are dispersed. The polymer polyol is preferably contained in the total high molecular weight polyol to be used in an amount of 20 to 100% by weight, more preferably 30 to 60% by weight. The high molecular weight polyol (including polymer polyol) is preferably contained in the active hydrogen-containing compound in an amount of 60 to 85% by weight, more preferably 70 to 80% by weight. By using a specific amount of the high molecular weight polyol, the cell membrane is easily broken, and an open cell structure is easily formed.

  Among the high molecular weight polyols, it is preferable to use a high molecular weight polyol having a hydroxyl value of 20 to 100 mgKOH / g. The hydroxyl value is more preferably 25 to 60 mgKOH / g. When the hydroxyl value is less than 20 mgKOH / g, the amount of polyurethane hard segments tends to decrease and the durability tends to decrease. When the hydroxyl value exceeds 100 mgKOH / g, the degree of crosslinking of the polyurethane foam becomes too high. Tend to be brittle.

  The number average molecular weight of the high molecular weight polyol is not particularly limited, but is preferably 1500 to 6000 from the viewpoint of the elastic properties of the resulting polyurethane. If the number average molecular weight is less than 1500, polyurethane using the same does not have sufficient elastic properties and tends to be a brittle polymer. For this reason, the foamed layer made of polyurethane becomes too hard, and scratches are likely to occur on the wafer surface. On the other hand, when the number average molecular weight exceeds 6000, a polyurethane resin using the number average molecular weight becomes too soft, and the foamed layer made of this polyurethane tends to have poor durability.

  Along with high molecular weight polyol, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, 3-methyl-1,5-pentanediol, diethylene glycol, triethylene glycol, 1,4-bis (2-hydroxyethoxy) benzene, tri Methylolpropane, glycerin, 1,2,6-hexanetriol, pentaerythritol, tetramethylolcyclohexane, methylglucoside, sorbitol, mannitol, dulcitol, sucrose, 2,2,6,6-tetrakis (hydroxymethyl) cyclo Hexanol, diethanolamine, N- methyldiethanolamine, and low molecular weight polyols such as triethanolamine may be used in combination. Moreover, low molecular weight polyamines, such as ethylenediamine, tolylenediamine, diphenylmethanediamine, and diethylenetriamine, can also be used in combination. Also, alcohol amines such as monoethanolamine, 2- (2-aminoethylamino) ethanol, and monopropanolamine can be used in combination. These low molecular weight polyols and low molecular weight polyamines may be used alone or in combination of two or more.

  Among these, it is preferable to use a low molecular weight polyol having a hydroxyl value of 400 to 1830 mgKOH / g and / or a low molecular weight polyamine having an amine value of 400 to 1870 mgKOH / g. The hydroxyl value is more preferably 700 to 1250 mgKOH / g, and the amine value is more preferably 400 to 950 mgKOH / g. When the hydroxyl value is less than 400 mgKOH / g or the amine value is less than 400 mgKOH / g, the effect of improving the formation of open cells tends to be insufficient. On the other hand, when the hydroxyl value exceeds 1830 mgKOH / g or the amine value exceeds 1870 mgKOH / g, scratches tend to occur on the wafer surface. In particular, it is preferable to use diethylene glycol, triethylene glycol, or 1,4-butanediol.

  In order to make the polyurethane foam layer into an open-cell structure, the low molecular weight polyol, the low molecular weight polyamine and the alcohol amine are preferably contained in a total of 2 to 15% by weight, more preferably 5 to 10% by weight in the active hydrogen-containing compound. %. By using a specific amount of the low molecular weight polyol or the like, not only the bubble film is easily broken and it becomes easy to form open cells, but also the mechanical properties of the polyurethane foam layer are improved.

  In the case of producing polyurethane by a prepolymer method, a chain extender is used for curing the isocyanate-terminated prepolymer. The chain extender is an organic compound having at least two active hydrogen groups, and 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) (MOCA), 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′-diamino-3,3′-diethyl-5,5′-dimethyl Diphenylmethane, N, N′-di-sec-butyl-4,4′-diaminodiphenylmethane, 3,3′-diethyl-4,4′-diaminodiphenylmethane, m-xyl Polyamines exemplified by N-diamine, N, N′-di-sec-butyl-p-phenylenediamine, m-phenylenediamine, and p-xylylenediamine, or the low molecular weight polyols and low molecular weight polyamines mentioned above. Can be mentioned. These may be used alone or in combination of two or more.

  The ratio of the isocyanate component, the polyol, and the chain extender can be variously changed depending on the molecular weight of each, the desired physical properties of the polyurethane foam layer, and the like. In order to obtain a foamed layer having desired characteristics, the number of isocyanate groups of the isocyanate component relative to the total number of active hydrogen groups (hydroxyl group + amino group) of the polyol and the chain extender is preferably 0.80 to 1.20. More preferably, it is 0.99 to 1.15. When the number of isocyanate groups is outside the above range, curing failure occurs and the required specific gravity, hardness, compression ratio, etc. tend not to be obtained.

  As the isocyanate-terminated prepolymer, those having a molecular weight of about 800 to 5000 are preferable because of excellent processability and physical characteristics. Further, when the prepolymer is solid at normal temperature, it is preheated to an appropriate temperature and melted before use.

  Examples of the silicon-based surfactant include those containing a copolymer of polyalkylsiloxane and polyether. As such a silicon-based surfactant, SH-192 and L-5340 (manufactured by Toray Dow Corning Silicone) are exemplified as suitable compounds.

  In addition, you may add stabilizers, such as antioxidant, a lubricant, a pigment, a filler, an antistatic agent, and another additive as needed.

  As the non-reactive gas used to form the fine bubbles, non-flammable gases are preferable, and specific examples include nitrogen, oxygen, carbon dioxide, rare gases such as helium and argon, and mixed gases thereof. In view of cost, it is most preferable to use air that has been dried to remove moisture.

  As a stirring device for dispersing the non-reactive gas in the form of fine bubbles, a known stirring device can be used without any particular limitation. Specifically, a homogenizer, a dissolver, a two-axis planetary mixer (planetary mixer), a mechanical A floss foaming machine etc. are illustrated. The shape of the stirring blade of the stirring device is not particularly limited, but it is preferable to use a whipper type stirring blade because fine bubbles can be obtained. In order to obtain the target polyurethane foam layer, the rotational speed of the stirring blade is preferably 500 to 2000 rpm, more preferably 800 to 1500 rpm. The stirring time is appropriately adjusted according to the target density.

  In addition, it is also a preferable aspect that the stirring for preparing the cell dispersion in the foaming step and the stirring for mixing the first component and the second component use different stirring devices. The agitation in the mixing step may not be agitation that forms bubbles, and it is preferable to use an agitation device that does not involve large bubbles. As such an agitator, a planetary mixer is suitable. There is no problem even if the same stirring device is used as the stirring device for the foaming step for preparing the bubble dispersion and the mixing step for mixing each component, and the stirring conditions such as adjusting the rotation speed of the stirring blades as necessary It is also suitable to use after adjustment.

  Then, the cell-dispersed urethane composition prepared by the above method is applied onto the base material layer, and the cell-dispersed urethane composition is cured to form a polyurethane foam layer (polishing layer).

  The substrate layer is not particularly limited, and examples thereof include plastic films such as nylon, polypropylene, polyethylene, polyester, and polyvinyl chloride, polyester nonwoven fabric, nylon nonwoven fabric, fiber nonwoven fabric such as acrylic nonwoven fabric, and polyester nonwoven fabric impregnated with polyurethane. Examples include resin-impregnated nonwoven fabrics, polymer resin foams such as polyurethane foam and polyethylene foam, rubber resins such as butadiene rubber and isoprene rubber, and photosensitive resins. Among these, it is preferable to use polymer resin foams such as plastic films such as nylon, polypropylene, polyethylene, polyester, and polyvinyl chloride, polyurethane foam, and polyethylene foam.

  The base material layer is preferably as hard as a polyurethane foam layer or harder in order to impart toughness to the polishing pad. Moreover, the thickness of the base material layer is not particularly limited, but is preferably 20 to 1000 μm, more preferably 50 to 800 μm from the viewpoint of strength, flexibility, and the like.

  As a method for applying the cell-dispersed urethane composition onto the base material layer, for example, a roll coater such as gravure, kiss, or comma, a die coater such as slot or phanten, a squeeze coater, or a curtain coater is adopted. Any method may be used as long as a uniform coating film can be formed on the base material layer.

  Heating and post-curing the polyurethane foam that has reacted until the cell-dispersed urethane composition is applied to the base material layer and no longer flows is effective in improving the physical properties of the polyurethane foam and is extremely suitable. is there. Post-cure is preferably performed at 40 to 70 ° C. for 10 to 60 minutes, and it is preferable to perform at normal pressure because the bubble shape becomes stable.

  In the production of the polyurethane foam layer, a known catalyst that promotes a polyurethane reaction, such as a tertiary amine, may be used. The type and addition amount of the catalyst are selected in consideration of the flow time for coating on the substrate layer after the mixing step of each component.

  The polyurethane foam layer may be produced by a batch method in which each component is weighed and put into a container and mechanically stirred. In addition, each component and a non-reactive gas are continuously supplied to a stirrer and mechanically stirred. Further, a continuous production method in which a cell-dispersed urethane composition is delivered onto a base material layer to produce a molded product may be used.

  In the manufacturing method of the polishing pad of the present invention, it is necessary to uniformly adjust the thickness of the polyurethane foam layer after forming the polyurethane foam layer on the base material layer or simultaneously with forming the polyurethane foam layer. . A method for uniformly adjusting the thickness of the polyurethane foam layer is not particularly limited, and examples thereof include a method of buffing with an abrasive and a method of pressing with a press plate.

  On the other hand, the cell-dispersed urethane composition prepared by the above method is applied on the base material layer, and a release sheet is laminated on the cell-dispersed urethane composition. Thereafter, the foam-dispersed urethane composition may be cured by making the thickness uniform with a pressing means to form a polyurethane foam layer.

  The material for forming the release sheet is not particularly limited, and examples thereof include general resin and paper. The release sheet preferably has a small dimensional change due to heat. The surface of the release sheet may be subjected to a release treatment.

  The pressing means for making the thickness of the sandwich sheet composed of the base material layer, the cell-dispersed urethane composition (cell-dispersed urethane layer), and the release sheet is not particularly limited. For example, the thickness may be constant by a coater roll, a nip roll, or the like. The method of compressing is mentioned. In consideration of the fact that the bubbles in the foamed layer become about 1.2 to 2 times larger after compression, the (coater or nip clearance)-(base layer and release sheet thickness) = (after curing) The thickness of the polyurethane foam layer is preferably 50 to 85%.

  Then, after the thickness of the sandwich sheet is made uniform, the reacted polyurethane foam is heated until it does not flow, and post-cured to form a polyurethane foam layer. Post cure conditions are the same as described above.

  Thereafter, the release sheet on the polyurethane foam layer is peeled off to obtain a polishing pad. In this case, since the skin layer is formed on the polyurethane foam layer, the skin layer is removed by buffing the polyurethane foam layer after peeling the release sheet.

  The shape of the polishing pad of the present invention is not particularly limited, and may be a long shape of about several meters in length or a round shape having a diameter of several tens of centimeters.

  The average cell diameter of the polyurethane foam layer (foam) is preferably 35 to 300 μm, more preferably 35 to 100 μm, and particularly preferably 40 to 80 μm. When deviating from this range, the polishing rate tends to decrease or the durability tends to decrease. Further, the polyurethane foam layer has an appropriate water retention due to the open cell structure.

  The specific gravity of the polyurethane foam layer is preferably 0.2 to 0.5. When the specific gravity is less than 0.2, the durability of the polishing layer tends to decrease. On the other hand, if it is larger than 0.5, it is necessary to make the material have a low crosslinking density in order to obtain a certain elastic modulus. In that case, the permanent set increases and the durability tends to deteriorate.

  The polyurethane foam layer preferably has a hardness of 10 to 50 degrees, more preferably 15 to 35 degrees as measured by an Asker C hardness meter. When the Asker C hardness is less than 10 degrees, the durability of the polishing layer tends to decrease, or the surface smoothness of the polished material after polishing tends to deteriorate. On the other hand, when it exceeds 50 degrees, scratches are likely to occur on the surface of the material to be polished.

  The polishing surface of the polyurethane foam layer that comes into contact with the object to be polished may have a concavo-convex structure for holding and renewing the slurry. The polishing layer made of foam has many openings on the polishing surface and has the function of holding and updating the slurry. By forming a concavo-convex structure on the polishing surface, the slurry can be held and updated more efficiently. It can be performed well, and destruction of the polishing object due to adsorption with the polishing object can be prevented. The concavo-convex structure is not particularly limited as long as it is a shape that holds and renews the slurry. For example, an XY lattice groove, a concentric circular groove, a through hole, a non-penetrating hole, a polygonal column, a cylinder, a spiral groove, Examples include eccentric circular grooves, radial grooves, and combinations of these grooves. In addition, these uneven structures are generally regular, but in order to make the slurry retention and renewability desirable, the groove pitch, groove width, groove depth, etc. should be changed for each range. Is also possible.

  The method for producing the concavo-convex structure is not particularly limited. For example, a method of machine cutting using a jig such as a tool of a predetermined size, or pressing a resin with a press plate having a predetermined surface shape. Examples thereof include a method, a production method using photolithography, a production method using a printing technique, and a production method using a laser beam using a carbon dioxide laser.

  Although the thickness of a polyurethane foam layer is not specifically limited, Usually, it is about 0.2-1.2 mm, and it is preferable that it is 0.3-0.8 mm.

  The polishing pad of the present invention may be provided with a double-sided tape on the surface to be bonded to the platen. As this double-sided tape, a tape having a general configuration in which an adhesive layer is provided on both sides of a substrate can be used.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated, this invention is not limited to these Examples.

[Measurement and evaluation methods]
(Measurement of average bubble diameter)
A sample obtained by cutting the produced polyurethane foam layer in parallel with a razor blade as thin as possible to a thickness of 1 mm or less was used as a sample. The sample was fixed on a slide glass and observed at 200 times using SEM (S-3500N, Hitachi Science Systems, Ltd.). Using the image analysis software (WinRoof, Mitani Shoji Co., Ltd.) for the obtained image, the total bubble diameter in an arbitrary range was measured, and the average bubble diameter was calculated. However, in the case of an oval spherical bubble, the area was converted to a circle area, and the equivalent circle diameter was taken as the bubble diameter.

(Measurement of specific gravity)
This was performed according to JIS Z8807-1976. The produced polyurethane foam layer was cut into a 4 cm × 8.5 cm strip (thickness: arbitrary) and used as a sample, and allowed to stand for 16 hours in an environment of temperature 23 ° C. ± 2 ° C. and humidity 50% ± 5%. The specific gravity was measured using a hydrometer (manufactured by Sartorius).

(Measurement of hardness)
This was performed according to JIS K-7312. A sample obtained by cutting the produced polyurethane foam layer into a size of 5 cm × 5 cm (thickness: arbitrary) was used as a sample and allowed to stand for 16 hours in an environment of a temperature of 23 ° C. ± 2 ° C. and a humidity of 50% ± 5%. At the time of measurement, the samples were overlapped to have a thickness of 10 mm or more. Using a hardness meter (manufactured by Kobunshi Keiki Co., Ltd., Asker C-type hardness meter, pressure surface height: 3 mm), the hardness 30 seconds after contacting the pressure surface was measured.

(Evaluation of polishing rate stability)
Using SPP600S (manufactured by Okamoto Machine Tool Co., Ltd.) as a polishing apparatus, the polishing rate stability of the manufactured polishing pad was evaluated. The evaluation results are shown in Table 1. The polishing conditions are as follows.
Glass plate: 6 inches φ, thickness 1.1 mm (optical glass, BK7)
Slurry: Ceria slurry (Showa Denko GPL C1010)
Slurry amount: 100 ml / min
Polishing pressure: 10kPa
Polishing platen rotation speed: 55rpm
Glass plate rotation speed: 50 rpm
Polishing time: 10 min / number of polished glass plates: 500 First, the polishing rate (Å / min) for each polished glass plate is calculated. The calculation method is as follows.
Polishing rate = [weight change amount of glass plate before and after polishing [g] / (glass plate density [g / cm ³ ] × polishing area of glass plate [cm ² ] × polishing time [min])] × 10 ⁸
The polishing rate stability (%) is the maximum polishing rate, the minimum polishing rate, and the total average polishing rate from the first glass plate to the number of processed sheets (100, 300, or 500 sheets). Is calculated by substituting that value into the following equation. As the polishing rate stability (%) is lower, the polishing rate is less likely to change even when a large number of glass plates are polished. In the present invention, the polishing rate stability after processing 500 sheets is preferably within 10%.
Polishing rate stability (%) = {(maximum polishing rate−minimum polishing rate) / total average polishing rate} × 100

Example 1
In a container, POP36 / 28 (Mitsui Chemical Co., Ltd., polymer polyol, hydroxyl value: 28 mgKOH / g) 45 parts by weight, ED-37A (Mitsui Chemicals, polyether polyol, hydroxyl value: 38 mgKOH / g) 40 parts by weight PCL305 (manufactured by Daicel Chemical Industries, Ltd., polyester polyol, hydroxyl value: 305 mg KOH / g), 10 parts by weight, 5 parts by weight of diethylene glycol, silicon surfactant (SH-192, manufactured by Toray Dow Corning Silicone) 5 parts by weight and 0.25 parts by weight of a catalyst (No. 25, manufactured by Kao) were added and mixed. And it stirred vigorously for about 4 minutes so that a bubble might be taken in in a reaction system with the rotation speed of 900 rpm using the stirring blade. Thereafter, 31.57 parts by weight of Millionate MTL (manufactured by Nippon Polyurethane Industry) was added and stirred for about 1 minute to prepare a cell dispersed urethane composition A.

  The prepared cell-dispersed urethane composition A was applied onto a base material layer (made by Toray Industries, trade name Pef, polyethylene foam, specific gravity 0.18, Asker C hardness 50) adjusted to a thickness of 0.8 mm by buffing. Thus, a cell-dispersed urethane layer was formed. Then, a release sheet (polyethylene terephthalate, thickness: 0.2 mm) subjected to a release treatment was put on the cell-dispersed urethane layer. The cell-dispersed urethane layer was made 1.0 mm thick with a nip roll, and then cured at 70 ° C. for 40 minutes to obtain a polyurethane foam layer (average cell diameter: 70 μm, average major axis / average minor axis = 1.3, specific gravity: 0.00. 34, C hardness: 23 degrees). Thereafter, the release sheet on the polyurethane foam layer was peeled off. Next, the surface of the polyurethane foam layer was buffed using a buffing machine (manufactured by Amitech) to make the thickness 0.8 mm, and the thickness accuracy was adjusted. Thereafter, a double-sided tape (double tack tape, manufactured by Sekisui Chemical Co., Ltd.) was bonded to the surface of the base material layer using a laminator to prepare a polishing pad. FIG. 1 shows a micrograph of a cross section of the polishing pad. It can be seen that substantially spherical open cells are formed in the polyurethane foam layer.

Example 2
POP36 / 28 (45 parts by weight), ED-37A (37.5 parts by weight), PCL305 (10 parts by weight), diethylene glycol 7.5 parts by weight, SH-192 (5.6 parts by weight), carbon black 0 5 parts by weight and 0.22 part by weight of catalyst (No. 25) were added and mixed. And it stirred vigorously for about 4 minutes so that a bubble might be taken in in a reaction system with the rotation speed of 900 rpm using the stirring blade. Thereafter, Millionate MTL (38.8 parts by weight) was added and stirred for about 1 minute to prepare a cell dispersed urethane composition B.

  A polishing pad was prepared in the same manner as in Example 1 except that the cell dispersed urethane composition B was used instead of the cell dispersed urethane composition A. When the cross section of the polishing pad was observed with a microscope, the polyurethane foam layer (average cell diameter: 66 μm, average major axis / average minor axis = 1.4, specific gravity: 0.35, C hardness: 29 degrees) was substantially spherical. Open cells were formed.

Example 3
POP36 / 28 (45 parts by weight), ED-37A (35 parts by weight), PCL305 (10 parts by weight), diethylene glycol 10 parts by weight, SH-192 (6.2 parts by weight), carbon black 0.5 parts by weight in a container , And 0.2 parts by weight of catalyst (No. 25) were added and mixed. And it stirred vigorously for about 4 minutes so that a bubble might be taken in in a reaction system with the rotation speed of 900 rpm using the stirring blade. Thereafter, Millionate MTL (46.04 parts by weight) was added and stirred for about 1 minute to prepare a cell dispersed urethane composition C.

  A polishing pad was prepared in the same manner as in Example 1 except that the cell dispersed urethane composition C was used in place of the cell dispersed urethane composition A. When the cross section of the polishing pad was observed with a microscope, the polyurethane foam layer (average cell diameter: 75 μm, average major axis / average minor axis = 1.3, specific gravity: 0.35, C hardness: 32 degrees) was substantially spherical. Open cells were formed.

Example 4
POP36 / 28 (45 parts by weight), ED-37A (30 parts by weight), PCL305 (10 parts by weight), diethylene glycol 15 parts by weight, SH-192 (6.6 parts by weight), carbon black 0.5 parts by weight in a container , And 0.15 parts by weight of catalyst (No. 25) were added and mixed. And it stirred vigorously for about 4 minutes so that a bubble might be taken in in a reaction system with the rotation speed of 900 rpm using the stirring blade. Thereafter, Millionate MTL (60.51 parts by weight) was added and stirred for about 1 minute to prepare a cell dispersed urethane composition D.

  A polishing pad was prepared in the same manner as in Example 1 except that the cell dispersed urethane composition D was used instead of the cell dispersed urethane composition A. When the cross section of the polishing pad was observed with a microscope, the polyurethane foam layer (average cell diameter: 78 μm, average major axis / average minor axis = 1.3, specific gravity: 0.35, C hardness: 31 degrees) was substantially spherical. Open cells were formed.

Example 5
A polishing pad was produced in the same manner as in Example 1 except that a base material layer (trade name E5001, manufactured by Toyobo Co., Ltd., polyester film) whose thickness was adjusted to 0.8 mm by buffing was used as the base material layer. . When the cross section of the polishing pad was observed with a microscope, the polyurethane foam layer (average cell diameter: 70 μm, average major axis / average minor axis = 1.3, specific gravity: 0.34, C hardness: 23 degrees) was substantially spherical. Open cells were formed.

表１から、本発明の研磨パッドは、気泡が略球状であるため耐久性及び研磨速度の安定性に優れることがわかる。 Comparative Example 1
A urethane solution was prepared by dissolving 10 parts by weight of thermoplastic urethane (Rezamin 7285, manufactured by Dainichi Seika) in 90 parts by weight of dimethylformamide. The urethane solution was applied onto a base material layer (Toyobo Co., Ltd., Borance 4211N, Asker C hardness 22) whose thickness was adjusted to 0.8 mm by buffing to form a urethane film. Thereafter, the urethane membrane-base material layer was immersed in a DMF-water mixture (DMF / water = 30/70) for 30 minutes, and further immersed in water for 24 hours to replace dimethylformamide with water, and a polyurethane foam layer (specific gravity) : 0.26, C hardness: 27 degrees). Next, the polyurethane foam layer surface was buffed using a buffing machine to make the thickness 0.8 mm, and the thickness accuracy was adjusted. Thereafter, a double-sided tape (double tack tape, manufactured by Sekisui Chemical Co., Ltd.) was bonded to the surface of the base material layer using a laminator to prepare a polishing pad. FIG. 2 shows a micrograph of a cross section of the polishing pad. It can be seen that elongated cocoon-shaped bubbles are formed in the polyurethane foam layer.

From Table 1, it can be seen that the polishing pad of the present invention is excellent in durability and stability of polishing rate because the bubbles are substantially spherical.

Micrograph (SEM photograph) of polishing pad in Example 1 Micrograph (SEM photograph) of the polishing pad in Comparative Example 1

Claims (6)

The step of preparing a cell-dispersed urethane composition by a mechanical foaming method, the step of applying a cell-dispersed urethane composition on a base material layer, and curing the cell-dispersed urethane composition to form a polyurethane foam layer having substantially spherical open cells And a step of uniformly adjusting the thickness of the polyurethane foam layer,
The cell-dispersed urethane composition contains an isocyanate component and an active hydrogen-containing compound, and the active hydrogen-containing compound contains 60 to 85% by weight of a high molecular weight polyol having a hydroxyl value of 20 to 100 mgKOH / g and a hydroxyl value of 400. A method for producing a polishing pad comprising 2 to 15 wt% of a low molecular weight polyol of ˜1830 mg KOH / g. The step of preparing the cell-dispersed urethane composition by the mechanical foaming method, the step of applying the cell-dispersed urethane composition on the base material layer, the step of laminating the release sheet on the cell-dispersed urethane composition, the thickness by the pressing means Including a step of curing the cell-dispersed urethane composition while being uniform to form a polyurethane foam layer having substantially spherical open cells, and a step of peeling the release sheet on the polyurethane foam layer,
The cell-dispersed urethane composition includes an isocyanate component and an active hydrogen-containing compound, and the active hydrogen-containing compound includes a high molecular weight polyol having a hydroxyl value of 20 to 100 mgKOH / g, 60 to 85% by weight, and a hydroxyl value of 400. A method for producing a polishing pad comprising 2 to 15 wt% of a low molecular weight polyol of ˜1830 mg KOH / g. In the polishing pad provided with the polyurethane foam layer on the base material layer, the polyurethane foam layer is made of a thermosetting polyurethane foam having substantially spherical open cells and is self-adhering to the base material layer. The thermosetting polyurethane foam is a reaction cured body of a cell-dispersed urethane composition containing an isocyanate component and an active hydrogen-containing compound, and the active hydrogen-containing compound has a high molecular weight having a hydroxyl value of 20 to 100 mgKOH / g. A group comprising 60 to 85% by weight of a polyol and 2 to 15% by weight of a low molecular weight polyol having a hydroxyl value of 400 to 1830 mg KOH / g, and the base layer is made of nylon, polyethylene, polypropylene, polyester, and polyvinyl chloride It is a non-foamed plastic film containing at least one resin selected from Polishing pad characterized. The polishing pad according to claim 3, wherein the thermosetting polyurethane foam has an average cell diameter of 35 to 300 μm. The polishing pad according to claim 3 or 4 , wherein the thermosetting polyurethane foam has a specific gravity of 0.2 to 0.5. The polishing pad according to claim 3 , wherein the thermosetting polyurethane foam has an Asker C hardness of 10 to 50 degrees.

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