JP5049844B2 - Laminated sheet - Google Patents

Description

  The present invention is a laminated sheet used for holding and fixing a surface of a lens, an optical material such as a reflection mirror, a semiconductor wafer such as a silicon wafer, a glass substrate, a metal substrate, and a disk, to a polishing head. The present invention relates to a laminated sheet (adhesive sheet) used for holding or protecting a product in a process of precisely processing a semiconductor product such as a (holding sheet, backing sheet) or semiconductor wafer or an optical product.

  A typical material that requires high surface flatness is a single crystal silicon disk called a silicon wafer for manufacturing a semiconductor integrated circuit (IC, LSI). Silicon wafers have a highly accurate surface in each process of stacking and forming oxide layers and metal layers in order to form reliable semiconductor junctions of various thin films used for circuit formation in IC, LSI, and other manufacturing processes. It is required to finish flat. In such a polishing finishing process, a polishing pad is generally fixed to a rotatable support disk called a platen, and a material to be polished such as a silicon wafer is fixed to a polishing head.

  Conventionally, as a method of fixing a material to be polished such as a silicon wafer or glass to a polishing head, (1) a wax mounting method in which the polishing head and the material to be polished are fixed via a wax, and (2) a method for fixing the material by suction. A vacuum chuck method in which the abrasive is fixed to the polishing head, or (3) a no-wax mounting method in which the material to be polished is fixed with artificial leather or a polymer foam sheet attached to the polishing head.

  Since the wax mounting method uses wax, it takes time to attach and detach the material to be polished, or it is necessary to clean the material after polishing to remove the wax, and the work process is complicated. have.

  The vacuum chuck method has a problem that the material to be polished is deformed at the suction port portion, and the surface accuracy of the material to be polished after polishing is thereby deteriorated.

  The no-wax mounting method has the advantage that the material to be polished is easy to attach and detach and has excellent production efficiency. However, if the surface accuracy of the holding surface of artificial leather or polymer foam sheet is poor, the coated material after polishing will be removed. There was a problem that the surface smoothness of the abrasive was also deteriorated.

  As a method for solving the problems of the no-wax mounting method, it has been proposed to use a backing material in which an adhesive resin layer made of a resin is provided on the surface of a foamed layer (Patent Document 1). In addition, a sheet-like elastic foam characterized in that closed cells having an elongated shape and a diameter increasing toward the surface of the foam layer is provided in the foam layer (Patent Document 2).

  However, the manufacturing method of the backing material of Patent Document 1 requires a separate adhesive resin layer, and the manufacturing process is complicated because the elastic layer is manufactured by wet coagulation. In addition, since a solvent must be used, there is a large environmental load, and there are manufacturing problems such that a large amount of water is required for solvent extraction.

  In Patent Document 2, it is difficult to form bubbles as described above, and since the porosity of the foam layer surface is large, the deformation of the foam layer becomes large. As a result, the surface smoothness of the polished material after polishing is increased. Is thought to be worse. In addition, air sticking occurs when the material to be polished is attached to the foamed layer, or water absorption of the slurry occurs between the foamed layer and the material to be polished due to low water absorption, reducing the adsorptivity of the material to be polished. There was a problem to do.

  In order to solve the above problem, the present applicant has proposed a laminated sheet comprising a base sheet and a polyurethane foam layer having spherical open cells (Patent Document 3). The present invention is an improved invention thereof.

JP 2002-355754 A JP-A-6-23664 JP 2007-245571 A

  An object of the present invention is to provide a laminated sheet having high surface accuracy of a holding surface and extremely excellent adsorptivity of a material to be polished.

  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 laminated sheet shown below, and have completed the present invention.

  That is, the present invention provides a laminated sheet comprising a base sheet and a polyurethane foam layer, wherein the polyurethane foam layer comprises a thermosetting polyurethane foam containing substantially spherical open cells having an average cell diameter of 20 to 300 μm. The thermosetting polyurethane foam contains an isocyanate component and an active hydrogen group-containing compound as raw material components, and the active hydrogen group-containing compound has an average hydroxyl value of 100 to 300 mgKOH / g and the number of functional groups. 2 to 4 and 50 to 100% by weight of a high molecular weight polyol having a hydroxyl value of 105 to 300 mgKOH / g, and the thermosetting polyurethane foam has a dynamic friction coefficient in a wet state of 0.5 or more. And a laminated sheet.

  Since the polyurethane foam layer of the laminated sheet of the present invention has substantially spherical open cells having an average cell diameter of 20 to 300 μm, it is continuous even if air is bitten when the material to be polished is attached to the polyurethane foam layer. Air can be discharged outside through the bubbles. Thereby, the material to be polished can be attached to the polyurethane foam layer with high flatness. In addition, even when the slurry enters between the foam layer and the material to be polished, the slurry can be absorbed into the polyurethane foam layer through the open cells, so the water film of the slurry between the foam layer and the material to be polished. Can be prevented. Therefore, it is possible to effectively prevent a decrease in the adsorptivity of the material to be polished. Moreover, since the open cell of a polyurethane foam layer is substantially spherical shape, it is excellent in durability. Therefore, when the material to be polished is polished using the laminated sheet having the foam layer, the stability of the polishing rate is improved.

  When the average cell diameter of the continuous cells is less than 20 μm, it becomes difficult for the slurry to be absorbed into the foam layer, and a water film of the slurry tends to be generated between the foam layer and the material to be polished. On the other hand, when it exceeds 300 μm, the smoothness of the foam layer surface is deteriorated, and local variations in the compression characteristics are likely to occur. Therefore, the surface smoothness of the polished material after polishing tends to be deteriorated.

  The polyurethane foam layer may contain closed cells together with the open cells, but the open cell ratio of the polyurethane foam layer is preferably 50% or more, more preferably 65% or more.

  The thermosetting polyurethane foam contains an isocyanate component and an active hydrogen group-containing compound as raw material components, and the active hydrogen group-containing compound has an average hydroxyl value of 100 to 300 mgKOH / g and has 2 functional groups. -4 and 50-100 weight% of high molecular weight polyols having a hydroxyl value of 105-300 mgKOH / g. By adjusting the average hydroxyl value of the active hydrogen group-containing compound within the above range and using a specific amount of the polymer polyol, the dynamic friction coefficient of the thermosetting polyurethane foam in a wet state can be increased. Thereby, the polyurethane foam layer which is very excellent in the adsorptivity of the material to be polished can be obtained. Moreover, the objective open cell can be formed stably and the mechanical characteristic of a polyurethane foam layer becomes favorable.

  When the average hydroxyl value of the active hydrogen group-containing compound is less than 100 mgKOH / g, “sagging” is likely to occur in the thermosetting polyurethane foam, so that the polishing stability is lowered and the average hydroxyl value exceeds 300 mgKOH / g. Is not preferable because the followability of the polyurethane foam layer to the material to be polished is deteriorated and the retainability of the material to be polished is lowered. The average hydroxyl value is preferably 130 to 200 mgKOH / g.

  In addition, when the content of the high molecular weight polyol in the active hydrogen group-containing compound is less than 50% by weight, the thermosetting polyurethane foam is difficult to have an open cell structure, which is not preferable.

  The high molecular weight polyol is preferably a polycaprolactone polyol, and the isocyanate component is preferably diphenylmethane diisocyanate and / or a modified product thereof. By using these compounds, the coefficient of dynamic friction in the wet state of the thermosetting polyurethane foam can be further increased, and a laminated sheet that is extremely excellent in the adsorptivity of the material to be polished can be obtained.

  The thermosetting polyurethane foam has an Asker C hardness of 20 to 50 degrees after 30 seconds of measurement, and a difference between the Asker C hardness of 1 second after measurement and the Asker C hardness after 30 seconds of measurement is 5 degrees or less. It is preferable. When the Asker C hardness after measurement of 30 seconds is less than 20 degrees, the durability tends to decrease or the surface smoothness of the polished material after polishing tends to deteriorate. On the other hand, if the Asker C hardness after 30 seconds of measurement exceeds 50 degrees, the retention of the material to be polished tends to deteriorate. Moreover, when the difference between the Asker C hardness after 1 second of measurement and the Asker C hardness after 30 seconds of measurement exceeds 5 degrees, the polishing stability tends to decrease.

  The thermosetting polyurethane foam preferably has a specific gravity of 0.2 to 0.6. When the specific gravity is less than 0.2, the bubble rate becomes too high and the durability tends to deteriorate. On the other hand, when the specific gravity exceeds 0.6, the material needs to have a low cross-linking density in order to obtain a certain elastic modulus. In that case, permanent set increases and durability tends to deteriorate.

  The laminated sheet of the present invention comprises a base sheet and a polyurethane foam layer, and the polyurethane foam layer comprises a thermosetting polyurethane foam (hereinafter referred to as polyurethane) containing substantially spherical open cells having an average cell diameter of 20 to 300 μm. Called foam).

  The polyurethane foam can be formed by, for example, curing a cell-dispersed urethane composition prepared by a mechanical foaming method (including a mechanical floss method) on a base sheet.

  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, and the cell-dispersed urethane composition is cured to reduce the bubble diameter, and the surface of the bubble is substantially circular. It is possible to easily form a polyurethane foam having substantially spherical open cells in which is formed. In addition, in the mechanical foaming method, gas such as air is dispersed without being dissolved in the raw material, so that new bubbles are generated after the process of uniformly adjusting the thickness of the polyurethane foam (post-foaming phenomenon). ) And the thickness accuracy and specific gravity can be easily controlled. Moreover, since it is not necessary to use a solvent, it is not only excellent in cost but also preferable from the environmental viewpoint.

  Specifically, 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 group-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 silicon-based surfactant was 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 group-containing compound, and the silicon-based surfactant was added. The components are mechanically stirred in the presence of a non-reactive gas, and the non-reactive gas is dispersed 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 group-containing compound, and the first component and the second component are added. Is mechanically stirred in the presence of a non-reactive gas, and the non-reactive gas is dispersed as fine bubbles to prepare a cell-dispersed urethane composition.

  Polyurethane is preferable as a material for forming a foamed layer of a laminated sheet because it can easily form substantially spherical open cells having substantially circular holes formed on the surface of the cells by mechanical foaming.

  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), urethane-modified MDI, allophanate-modified MDI, burette-modified MDI, 1,5-naphthalene diisocyanate, p-phenylene diisocyanate, m-phenylene diisocyanate, p-xylylene diisocyanate, m-xylylene diisocyanate Aromatic diisocyanate, ethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 1,6-hexa Aliphatic diisocyanates such as Chi diisocyanate, 1,4-cyclohexane 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.

  Among the above isocyanate components, 2,2′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, and diphenylmethane diisocyanate (MDI) such as 4,4′-diphenylmethane diisocyanate, polymeric MDI, carbodiimide-modified MDI, urethane-modified MDI, It is preferable to use modified MDI such as allophanate-modified MDI and burette-modified MDI.

  The active hydrogen group-containing compound is a high molecular weight polyol having active hydrogen that reacts with an isocyanate component, a low molecular weight polyol, a low molecular weight polyamine, and an alcohol amine.

  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 the present invention, it is necessary to use a high molecular weight polyol having 2 to 4 functional groups and a hydroxyl value of 105 to 300 mgKOH / g. The hydroxyl value is preferably 105 to 200 mgKOH / g. Moreover, it is preferable to use polycaprolactone polyols such as polycaprolactone diol, polycaprolactone triol, and polycaprolactone tetraol as the high molecular weight polyol. The high molecular weight polyol needs to be contained in the active hydrogen group-containing compound in an amount of 50 to 100% by weight, and preferably 60 to 90% by weight.

  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, methyl glucoside, sorbitol, mannitol, dulcitol, sucrose, 2,2,6,6-tetrakis (hydroxymethyl) cyclo Low molecular weight polyols such as xanol, diethanolamine, N-methyldiethanolamine, and triethanolamine; low molecular weight polyamines such as ethylenediamine, tolylenediamine, diphenylmethanediamine, and diethylenetriamine; monoethanolamine, 2- (2-aminoethylamino) ethanol , And low molecular weight components such as alcohol amines such as monopropanolamine may be used in combination. These low molecular weight components 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, the distance between the hard segments of the polyurethane is shortened, and the effect of improving the adsorptivity of the polishing material cannot be sufficiently obtained. There is a tendency. In particular, it is preferable to use diethylene glycol, triethylene glycol, trimethylolpropane, or 1,4-butanediol.

  When using the said low molecular weight component, it is necessary to use it so that the average hydroxyl value of an active hydrogen group containing compound may be 100-300 mgKOH / g.

上記式において、ｎは高分子量ポリオール及び低分子量成分の数、ａｉは水酸基価、ｃｉは添加重量部である。例えば、使用する活性水素基含有化合物が第１〜第ｎ成分まである場合、第１成分の水酸基価をａ１、及び添加重量部をｃ１とし、・・・、第ｎ成分の水酸基価をａｎ、及び添加重量部をｃｎとする。 The average hydroxyl value (OHVav) of the active hydrogen group-containing compound is determined by the following formula.

In the above formula, n is the number of high molecular weight polyols and low molecular weight components, ai is the hydroxyl value, and ci is parts by weight. For example, when the active hydrogen group-containing compound to be used is from the first to the n-th component, the hydroxyl value of the first component is a1, the added weight part is c1, ..., the hydroxyl value of the n-th component is an, And the added weight part is cn.

  In the case of producing polyurethane by the prepolymer method, the kind and compounding ratio of the active hydrogen group-containing compound used at the time of synthesizing and curing the isocyanate-terminated prepolymer are not particularly limited. It is preferable to use 80% by weight or more of a high molecular weight polyol in the compound and 80% by weight or more of a low molecular weight component in the active hydrogen group-containing compound when curing the isocyanate-terminated prepolymer. Use of such an active hydrogen group-containing compound is a preferable method from the viewpoints of the stability and productivity of the physical properties of the resulting polyurethane.

  The ratio of the isocyanate component, the high molecular weight polyol, and the low molecular weight component can be variously changed depending on the molecular weight of each component and the desired physical properties of the polyurethane foam layer. 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) is preferably 0.80 to 1.20, more preferably 0.8. 99 to 1.15. When the number of isocyanate groups is out of the above range, curing failure occurs, and required open cells, specific gravity, hardness, compression rate, and the like tend not to be obtained.

  As the isocyanate-terminated prepolymer, those having a molecular weight of about 1000 to 10,000 are preferable because they have 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 polyalkylsiloxane or a copolymer of an alkylsiloxane and a polyetheralkylsiloxane. Examples of suitable silicon surfactants include SH-192 and L-5340 (manufactured by Toray Dow Corning Silicone), B-8443 (manufactured by Goldschmidt), and the like.

  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 the 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, etc. 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 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 are adjusted as necessary. It is also suitable to use after adjustment.

  And the cell dispersion | distribution urethane composition prepared by the said method is apply | coated on a base material sheet, this cell dispersion | distribution urethane composition is hardened, and the polyurethane foam layer which consists of a polyurethane foam is formed.

  The material for forming the base sheet is not particularly limited, and examples thereof include fluorine-containing resins such as polyethylene terephthalate, polyester, polyethylene, polypropylene, polystyrene, polyimide, polyvinyl alcohol, polyvinyl chloride, and polyfluoroethylene, nylon, and cellulose. Can do.

  The thickness of the base sheet is not particularly limited, but is preferably about 0.05 to 0.3 mm from the viewpoints of strength, flexibility and the like.

  As a method for applying the cell-dispersed urethane composition onto the base sheet, 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 sheet.

  Heating and post-curing the polyurethane foam that has reacted until the cell-dispersed urethane composition is applied to the base sheet 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 kind and addition amount of the catalyst are selected in consideration of the flow time for application on the base sheet 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 sent out to produce a molded product may be used.

  In the method for producing a laminated sheet 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 sheet 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. When buffing is performed, a laminated sheet having no skin layer on the surface of the polyurethane foam layer is obtained, and when pressed, a laminated sheet having a skin layer on the surface of the polyurethane foam layer is obtained. The conditions for pressing are not particularly limited, but it is preferable to adjust the temperature above the glass transition point.

  On the other hand, the cell-dispersed urethane composition prepared by the above method is applied onto a substrate sheet, and a release sheet is laminated on the cell-dispersed urethane composition. Thereafter, the cell-dispersed urethane composition may be cured while the thickness is made uniform by a pressing means to form a polyurethane foam layer made of a polyurethane foam. This method is a particularly preferable method because the thickness of the laminated sheet can be controlled extremely uniformly.

  The material for forming the release sheet is not particularly limited, and examples thereof include the same resin and paper as those for the base sheet. 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 sheet, 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, during the compression, (coater or nip clearance)-(base sheet and release sheet thickness) = (after curing) The thickness of the polyurethane foam layer is preferably 50 to 85%. In order to obtain a polyurethane foam layer having a specific gravity of 0.2 to 0.5, the specific gravity of the cell-dispersed urethane composition before passing through the roll is preferably 0.24 to 1.

  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 laminated sheet. In this case, a skin layer is formed on the polyurethane foam layer. Note that the skin layer may be removed by buffing the polyurethane foam layer after the release sheet is peeled off.

  The thickness of the polyurethane foam layer is not particularly limited, but is preferably 0.2 to 1.2 mm, and more preferably 0.3 to 0.8 mm.

  The polyurethane foam layer has substantially spherical open cells in which substantially circular holes are formed on the cell surface. The open bubbles are not formed by crushing.

  The average cell diameter of the open cells in the polyurethane foam needs to be 20 to 300 μm, preferably 50 to 150 μm. Further, the average diameter of the substantially circular holes on the bubble surface is preferably 100 μm or less, more preferably 50 μm or less.

  The polyurethane foam needs to have a coefficient of dynamic friction in a wet state of 0.5 or more, and preferably 0.6 or more.

  The specific gravity of the polyurethane foam is preferably 0.2 to 0.6, more preferably 0.3 to 0.5.

  The hardness of the polyurethane foam is preferably 20 to 50 degrees in terms of Asker C hardness after 30 seconds of measurement, and more preferably 30 to 50 degrees. Further, the difference between the Asker C hardness after 1 second of measurement and the Asker C hardness after 30 seconds of measurement is preferably 5 degrees or less, more preferably 3 degrees or less.

  The thickness variation of the polyurethane foam layer is preferably 100 μm or less, more preferably 60 μm or less. When the thickness variation exceeds 100 μm, the laminated sheet has large undulations. As a result, the surface smoothness of the polished material after polishing tends to deteriorate.

  A double-sided tape for attaching to the polishing head may be provided on the surface of the base sheet of the laminated sheet. The double-sided tape has a general configuration in which adhesive layers are provided on both sides of a substrate such as a nonwoven fabric or a film. Examples of the composition of the adhesive layer include rubber adhesives and acrylic adhesives.

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

(Measurement of average cell diameter of open cells and average diameter of circular holes)
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 glass slide and observed at 100 times using SEM (S-3500N, Hitachi Science Systems, Ltd.). Using the image analysis software (WinRoof, Mitani Shoji Co., Ltd.), the obtained images were all measured for the bubble diameter of open cells in an arbitrary range, and the average bubble diameter was calculated from the value. Moreover, all the diameters of the circular holes of the open cells in an arbitrary range were measured, and the average diameter was calculated from the value.

(Measurement of open cell ratio)
The open cell ratio was measured according to the ASTM-2856-94-C method. However, 10 polyurethane foam layers punched into a circle were stacked as a measurement sample. As a measuring instrument, an air comparison type hydrometer 930 type (manufactured by Beckman Co., Ltd.) was used. The open cell ratio was calculated by the following formula.
Open cell ratio (%) = [(V−V1) / V] × 100
V: Apparent volume calculated from sample size (cm ³ )
V1: Sample volume (cm ³ ) measured using an air-comparing hydrometer

(Measurement of dynamic friction coefficient in wet condition [wet μ])
The produced laminated sheet was punched into a circular shape with a diameter of 25 mm to obtain a sample. The sample was immersed in pure water at a temperature of 23 ° C. ± 2 ° C. for 1 hour. Then, the sample was taken out and the moisture adhering to the surface was wiped off. For the measurement, HEIDON tribogear (manufactured by Shinto Kagaku Co., Ltd., Muse TYPE: 94i) was used. The sample was fixed with a double-sided tape to a circular measuring jig having a diameter of 25 mm on the bottom of the tribogear. A glass plate (manufactured by SCHOTT DES AG, B270) was placed in the tray and allowed to stand on the glass plate so that the tribogear was horizontal. Then, pure water was poured into the tray so that the contact surface between the glass plate and the sample was sufficiently immersed, and then the coefficient of dynamic friction [wet μ] was measured.

(Specific gravity measurement)
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).

(Hardness measurement)
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 after 1 second and 30 seconds after the contact of the pressure surface was measured.

Example 1
Polycaprolactone diol (manufactured by Daicel Chemical, Plaxel 210N, OHV: 110, functional group number: 2) 80 parts by weight in a container, polycaprolactone triol (manufactured by Daicel Chemical, Plaxel 305, OHV: 305, functional group number: 3) 18 parts by weight, 2 parts by weight of trimethylolpropane (OHV: 1254, functional group number: 3), 10 parts by weight of a silicon-based surfactant (SH-192, manufactured by Toray Dow Corning Silicone), and a catalyst (No. 25, manufactured by Kao) 0.1 part by weight was added and mixed to prepare the second component (25 ° C.). The average hydroxyl value (OHVav) is 168.0 mgKOH / g (calculated value). And it stirred vigorously for about 7 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, 47.7 parts by weight of carbodiimide-modified MDI (manufactured by Nippon Polyurethane Industry Co., Ltd., Millionate MTL, NCO wt%: 29 wt%, 25 ° C.) as the first component was added to the second component (NCO / OH = 1) 0.1) Stirred for about 1 minute to prepare a cell dispersed urethane composition.

  The prepared cell-dispersed urethane composition was applied on a base sheet (polyethylene terephthalate, thickness: 0.2 mm) to form a cell-dispersed urethane layer. 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 0.8 mm thick with nip rolls (clearance: 0.75 mm), and then cured at 40 ° C. for 60 minutes to form a polyurethane foam layer. Thereafter, the release sheet on the polyurethane foam layer was peeled off. And the laminated sheet was produced by bonding a double-sided tape (double tack tape, Sekisui Chemical Co., Ltd.) using the laminating machine on the base-material sheet surface. When the cross section of the polyurethane foam layer was observed with a microscope, spherical open cells in which circular holes were formed on the cell surface were mainly formed.

Example 2
A cell-dispersed urethane composition was prepared in the same manner as in Example 1 except that the addition amount of the silicon-based surfactant was changed from 10 parts by weight to 6 parts by weight and the stirring time was changed from about 7 minutes to about 4 minutes. did. And the lamination sheet was produced by the method similar to Example 1 except having used this cell dispersion urethane composition. When the cross section of the polyurethane foam layer was observed with a microscope, spherical open cells in which circular holes were formed on the cell surface were mainly formed.

Example 3
A cell-dispersed urethane composition was prepared in the same manner as in Example 1 except that the addition amount of the silicon-based surfactant was changed from 10 parts by weight to 3 parts by weight and the stirring time was changed from about 7 minutes to about 3 minutes. did. And the lamination sheet was produced by the method similar to Example 1 except having used this cell dispersion urethane composition. When the cross section of the polyurethane foam layer was observed with a microscope, spherical open cells in which circular holes were formed on the cell surface were mainly formed.

Example 4
Plaxel 210N (88 parts by weight), Plaxel 305 (10 parts by weight), trimethylolpropane (2 parts by weight), SH-192 (6 parts by weight), and No. 25 (0.15 parts by weight) was added and mixed to prepare a second component (25 ° C.). The average hydroxyl value (OHVav) is 152.4 mgKOH / g (calculated value). 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, carbodiimide-modified MDI (43.3 parts by weight) as the first component was added to the second component (NCO / OH = 1.1) and stirred for about 1 minute to prepare a cell-dispersed urethane composition.

  And the lamination sheet was produced by the method similar to Example 1 except having used this cell dispersion urethane composition. When the cross section of the polyurethane foam layer was observed with a microscope, spherical open cells in which circular holes were formed on the cell surface were mainly formed.

Example 5
Plaxel 210N (80 parts by weight), Plaxel 305 (15 parts by weight), trimethylolpropane (5 parts by weight), SH-192 (6 parts by weight), and No. 25 (0.08 parts by weight) was added and mixed to prepare a second component (25 ° C.). The average hydroxyl value (OHVav) is 196.5 mgKOH / g (calculated value). 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, carbodiimide-modified MDI (55.8 parts by weight) as the first component was added to the second component (NCO / OH = 1.1) and stirred for about 1 minute to prepare a cell-dispersed urethane composition.

  And the lamination sheet was produced by the method similar to Example 1 except having used this cell dispersion urethane composition. When the cross section of the polyurethane foam layer was observed with a microscope, spherical open cells in which circular holes were formed on the cell surface were mainly formed.

Example 6
High-molecular-weight polyol EX-5030 (manufactured by Asahi Glass Co., Ltd., OHV: 33, number of functional groups: 3) 20 parts by weight, Plaxel 210N (60 parts by weight), Plaxel 305 (18 parts by weight), Trimethylolpropane (2 parts by weight) ), SH-192 (6 parts by weight), and No. 25 (0.18 parts by weight) was added and mixed to prepare a second component (25 ° C.). The average hydroxyl value (OHVav) is 152.6 mgKOH / g (calculated value). 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, carbodiimide-modified MDI (43.3 parts by weight) as the first component was added to the second component (NCO / OH = 1.1) and stirred for about 1 minute to prepare a cell-dispersed urethane composition.

  And the lamination sheet was produced by the method similar to Example 1 except having used this cell dispersion urethane composition. When the cross section of the polyurethane foam layer was observed with a microscope, spherical open cells in which circular holes were formed on the cell surface were mainly formed.

Example 7
In a container, high molecular weight polyol EX-5030 (20 parts by weight), Plaxel 210N (60 parts by weight), Plaxel 308 (manufactured by Daicel Chemical Industries, OHV: 197, functional group number: 3) 18 parts by weight, trimethylolpropane (2 parts by weight) , SH-192 (6 parts by weight), and No. 25 (0.18 parts by weight) was added and mixed to prepare a second component (25 ° C.). The average hydroxyl value (OHVav) is 133.2 mgKOH / g (calculated value). 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, carbodiimide-modified MDI (37.8 parts by weight) as the first component was added to the second component (NCO / OH = 1.1) and stirred for about 1 minute to prepare a cell-dispersed urethane composition.

  And the lamination sheet was produced by the method similar to Example 1 except having used this cell dispersion urethane composition. When the cross section of the polyurethane foam layer was observed with a microscope, spherical open cells in which circular holes were formed on the cell surface were mainly formed.

Comparative Example 1
High molecular weight polyol EX-5030 (60 parts by weight), Plaxel 305 (40 parts by weight), SH-192 (5 parts by weight), and No. 25 (0.18 parts by weight) was added and mixed to prepare a second component (25 ° C.). The average hydroxyl value (OHVav) is 141.8 mgKOH / g (calculated value). 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, carbodiimide-modified MDI (40.3 parts by weight) as the first component was added to the second component (NCO / OH = 1.1) and stirred for about 1 minute to prepare a cell-dispersed urethane composition.

  And the lamination sheet was produced by the method similar to Example 1 except having used this cell dispersion urethane composition. When the cross section of the polyurethane foam layer was observed with a microscope, spherical open cells in which circular holes were formed on the cell surface were mainly formed.

Comparative Example 2
In a container, high molecular weight polyol EX-5030 (85 parts by weight), Plaxel 305 (13 parts by weight), diethylene glycol (OHV: 1057, functional group number: 2), 2 parts by weight, SH-192 (5 parts by weight), 25 (0.34 parts by weight) was added and mixed to prepare a second component (25 ° C.). The average hydroxyl value (OHVav) is 88.8 mgKOH / g (calculated value). 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, carbodiimide-modified MDI (25.2 parts by weight) as the first component was added to the second component (NCO / OH = 1.1) and stirred for about 1 minute to prepare a cell-dispersed urethane composition.

  And the lamination sheet was produced by the method similar to Example 1 except having used this cell dispersion urethane composition. When the cross section of the polyurethane foam layer was observed with a microscope, spherical open cells in which circular holes were formed on the cell surface were mainly formed.

Comparative Example 3
Polymer polyol EX-940 (manufactured by Asahi Glass Co., Ltd., OHV: 28, converted to functional group number: 3) 45 parts by weight, polytetramethylene ether glycol (Mitsubishi Chemical Co., Ltd.) in which polymer particles made of styrene-acrylonitrile copolymer are dispersed in a container Industrial Co., Ltd., PTMG2000, OHV: 56, functional group number: 2) 35 parts by weight, Plaxel 305 (10 parts by weight), diethylene glycol (10 parts by weight), SH-192 (5 parts by weight) 25 (0.25 part by weight) was added and mixed to prepare the second component (25 ° C.). The average hydroxyl value (OHVav) is 137.4 mgKOH / g (calculated value). 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 (39 parts by weight) as the first component was added to the second component (NCO / OH = 1.1) and stirred for about 1 minute to prepare a cell dispersed urethane composition.

  And the lamination sheet was produced by the method similar to Example 1 except having used this cell dispersion urethane composition. When the cross section of the polyurethane foam layer was observed with a microscope, spherical open cells in which circular holes were formed on the cell surface were mainly formed.

Comparative Example 4
PTMG2000 (700 parts by weight), polytetramethylene ether glycol (manufactured by Mitsubishi Chemical Co., Ltd., PTMG650, OHV: 173, number of functional groups: 2) 150 parts by weight are placed in a container, and dehydration under reduced pressure is performed for about 1 hour. It was. Thereafter, the inside of the reaction vessel was purged with nitrogen. Then, 436 parts by weight of Millionate MT (manufactured by Nippon Polyurethane Industry Co., Ltd., Pure MDI) was added to the reaction vessel. Then, it was made to react for about 4 hours, keeping the temperature in a reaction system at about 80 degreeC, and the isocyanate terminal prepolymer A (NCOwt%: 7.53wt%) was synthesize | combined.

  An isocyanate-terminated prepolymer A (128 parts by weight) and SH-192 (5 parts by weight) were mixed in a container, adjusted to 40 ° C., and degassed under reduced pressure to prepare a first component. 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, 15 parts by weight of triethylene glycol (OHV: 747, functional group number: 2) adjusted to 25 ° C. A second component mixed with 25 (0.12 parts by weight) was added to the first component (NCO / OH = 1.15) and stirred for about 1 minute to prepare a cell dispersed urethane composition. The average hydroxyl value (OHVav) is 177.2 mg KOH / g (calculated value).

And the lamination sheet was produced by the method similar to Example 1 except having used this cell dispersion urethane composition. When the cross section of the polyurethane foam layer was observed with a microscope, spherical open cells in which circular holes were formed on the cell surface were mainly formed.

Claims (5)

In the laminated sheet comprising a base sheet and a polyurethane foam layer, the polyurethane foam layer comprises a thermosetting polyurethane foam containing substantially spherical open cells having an average cell diameter of 20 to 300 μm, and the thermosetting polyurethane The foam contains an isocyanate component and an active hydrogen group-containing compound as raw material components, and the active hydrogen group-containing compound has an average hydroxyl value of 100 to 300 mgKOH / g, a functional group number of 2 to 4, and a hydroxyl value. The laminate sheet is characterized in that it contains 50 to 100% by weight of a high molecular weight polyol of 105 to 300 mg KOH / g, and the thermosetting polyurethane foam has a coefficient of dynamic friction in a wet state of 0.5 or more. The laminated sheet according to claim 1, wherein the high molecular weight polyol is a polycaprolactone polyol. The laminated sheet according to claim 1 or 2, wherein the isocyanate component is diphenylmethane diisocyanate and / or a modified product thereof. The thermosetting polyurethane foam has an Asker C hardness of 20 to 50 degrees after 30 seconds of measurement, and a difference between the Asker C hardness of 1 second after measurement and the Asker C hardness after 30 seconds of measurement is 5 degrees or less. The laminated sheet according to any one of claims 1 to 3. The laminated sheet according to any one of claims 1 to 4, wherein the thermosetting polyurethane foam has a specific gravity of 0.2 to 0.6.