JP2007245299A - Method for manufacturing laminated sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for very easily manufacturing a laminated sheet excellent in surface accuracy of holding surface and adsorptive property of polished material, and a laminated sheet obtained by the manufacturing method. <P>SOLUTION: The method for manufacturing a laminated sheet comprises: a step of preparing a bubble dispersed urethane composition with a mechanical bubbling method, a step of coating the bubble dispersed urethane composition on a substrate sheet, a step of laminating a parting sheet with a nitrogen gas permeation velocity of 1×10<SP>-7</SP>(cm<SP>3</SP>/cm<SP>2</SP>×s×cm Hg) or less on a coated bubble dispersed urethane composition, and a step of curing the bubble dispersed urethane composition while making its thickness even with a pressing means to form a polyurethane bubble layer having continuous bubbles. <P>COPYRIGHT: (C)2007,JPO&INPIT

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 a semiconductor wafer, or an optical system product, and a method for manufacturing the same.

  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. Further, in Patent Document 2, it is difficult to form bubbles as described above, and since the porosity of the foam layer surface is large, deformation of the foam layer increases, and as a result, the surface of the material to be polished after polishing is obtained. It is thought that the smoothness becomes 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.

JP 2002-355754 A JP-A-6-23664

  An object of this invention is to provide the method of manufacturing the laminated sheet which has the high surface precision of a holding surface, and is excellent in the adsorptivity of a to-be-polished material very easily. Moreover, it aims at providing the lamination sheet obtained by this manufacturing method.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the above object can be achieved by the production 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 sheet, and a nitrogen gas transmission rate of 1 × 10 ⁻⁷ [cm ³ / cm ² · s · cmHg] or less, a step of laminating a release sheet on the applied cell-dispersed urethane composition, a polyurethane having open cells by curing the cell-dispersed urethane composition while making the thickness uniform by pressing means The present invention relates to a method for producing a laminated sheet including a step of forming a foam layer.

  As described above, a gas such as air is dispersed as fine bubbles in a raw material by a mechanical foaming method to prepare a cell-dispersed urethane composition, and the cell diameter is extremely small by curing the cell-dispersed urethane composition, and A polyurethane foam layer having spherical (including 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. Moreover, since it is not necessary to use a solvent, it is not only excellent in cost but also preferable from the environmental viewpoint.

Further, in the production method of the present invention, a release sheet having a nitrogen gas transmission rate of 1 × 10 ⁻⁷ [cm ³ / cm ² · s · cmHg] or less is laminated on the applied cell-dispersed urethane composition. When the fine bubbles in the cell-dispersed urethane composition are broken to form continuous cells, the gas inside the fine bubbles can be held in the composition and discharged to the external environment. Can be prevented. Thereby, it can suppress that the thickness of a cell dispersion | distribution urethane composition changes at the time of a hardening process, and can raise the surface precision of the polyurethane foam layer after hardening.

In the present invention, the base sheet preferably has a nitrogen gas permeation rate of 1 × 10 ⁻⁷ [cm ³ / cm ² · s · cmHg] or less. By using the base sheet, the above effects are further improved.

  Moreover, in this invention, it is preferable that the said base material sheet is a polyethylene terephthalate (PET) film, and the said release sheet is a polyethylene terephthalate film which gave the mold release process. PET film is a suitable material because of its particularly low nitrogen gas transmission rate.

  The laminated sheet of the present invention is obtained by the production method. Since the polyurethane foam layer of the laminated sheet of the present invention has spherical (including elliptical spherical) open cells, even if air is bitten when the material to be polished is attached to the polyurethane foam layer, Air can be discharged to the outside. 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. In addition, since the polyurethane foam layer has extremely high surface accuracy of the holding surface for holding the material to be polished, when the material to be polished is held using a laminated sheet having the foam layer, the material to be polished after polishing is used. The surface smoothness is extremely excellent. Moreover, since the said polyurethane foam layer has a spherical cell, 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.

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

  It is preferable that the average cell diameter of the open cell of the said polyurethane foam layer is 20-300 micrometers. The specific gravity of the polyurethane foam layer is preferably 0.2 to 0.5. The Asker C hardness of the polyurethane foam layer is preferably 10 to 50 degrees. Furthermore, the compression ratio of the polyurethane foam layer is preferably 2 to 10%.

The method for producing a laminated sheet of 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 sheet, and a nitrogen gas transmission rate of 1 × 10 ⁻⁷ [ cm ³ / cm ² · s · cmHg] or less, a step of laminating the release sheet on the applied cell-dispersed urethane composition, and continuously curing the cell-dispersed urethane composition while making the thickness uniform by pressing means Forming a polyurethane foam layer having air bubbles.

  The cell-dispersed urethane composition may be prepared by a mechanical foaming method (including a mechanical floss method), and the others are not particularly limited. 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.

  Polyurethane is a preferred material for forming the foamed layer of the laminated sheet because it can easily form spherical open 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), 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 active hydrogen-containing compound include a high molecular weight polyol having an active hydrogen that reacts with an isocyanate component, a low molecular weight polyol, and a low molecular weight polyamine.

  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 and polyethylene glycol, 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 polyols which are polyether polyols in which polymer particles are dispersed.These may be used alone or in combination of two or more.

  Among the high molecular weight polyols, it is preferable to use a high molecular weight polyol having 2 to 4 functional groups and a hydroxyl value of 20 to 100 mgKOH / g. The hydroxyl value is more preferably 25 to 60 mgKOH / g. When the number of functional groups is 5 or more, the cross-linking degree of the polyurethane foam becomes too high, and the adsorptivity of the material to be polished tends to decrease. 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. The adsorptivity of the material to be polished tends to be reduced.

  Moreover, it is also 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.

  These specific high molecular weight polyols are 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 specific high molecular weight polyol, the cell membrane is easily broken, and the intended open cell is easily formed.

  Along with a high molecular weight polyol, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, 3- Low molecular weight polyols such as methyl-1,5-pentanediol, diethylene glycol, triethylene glycol, and 1,4-bis (2-hydroxyethoxy) benzene may be used. Further, low molecular weight polyamines such as tolylenediamine and diphenylmethanediamine may be used in combination. Moreover, you may use together the polyol which added alkylene oxides, such as ethylene oxide and a propylene oxide, to the said low molecular weight polyol or low molecular weight polyamine.

  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, or 1,4-butanediol.

  Moreover, it is preferable to make these low molecular weight polyol and / or low molecular weight polyamine contain 2 to 15 weight% in an active hydrogen containing compound, More preferably, it is 5 to 10 weight%. By using a specific amount of the low molecular weight polyol and / or the low molecular weight polyamine, the cell membrane is easily broken and not only the target open cell is easily formed, but also the mechanical properties of the polyurethane foam layer are improved.

上記式において、ｎはポリオール成分の数、ａｉは水酸基価、ｂｉは官能基数、ｃｉは添加重量部である。
例えば、使用する活性水素含有化合物が第１〜第ｎポリオール成分まである場合、第１ポリオール成分の水酸基価をａ１、官能基数をｂ１、及び添加重量部をｃ１とし、・・・、第ｎポリオール成分の水酸基価をａｎ、官能基数をｂｎ、及び添加重量部をｃｎとする。ただし、ポリマーポリオールについてはポリマー粒子が分散しているため、どの種類においても官能基数は３として計算する。 Moreover, it is preferable that the average hydroxyl value (OHVav) of the active hydrogen containing compound to be used exists in the range of a following formula.
(350-80 × fav−120 / fav) ≦ OHVav ≦ (350-80 × fav + 120 / fav)
In the above formula, OHVav and fav (average functional group number) are calculated by the following formula.

In the above formula, n is the number of polyol components, ai is the hydroxyl value, bi is the number of functional groups, and ci is the weight part added.
For example, when the active hydrogen-containing compound to be used is from the first to the n-th polyol component, the hydroxyl value of the first polyol component is a1, the number of functional groups is b1, and the addition part by weight is c1,. The hydroxyl value of the component is an, the number of functional groups is bn, and the added weight part is cn. However, since polymer particles are dispersed with respect to the polymer polyol, the number of functional groups is calculated as 3 in any kind.

  In the case of producing polyurethane by the prepolymer method, the type and blending ratio of the active hydrogen-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 high molecular weight polyol and 80% by weight or more of low molecular weight polyol and / or low molecular weight polyamine in the active hydrogen-containing compound when the isocyanate-terminated prepolymer is cured. Use of such active hydrogen-containing compounds is a preferable method from the viewpoint of the stability and productivity of the physical properties of the resulting polyurethane.

  The ratio of the isocyanate component, the high molecular weight polyol, the low molecular weight polyol, and the low molecular weight polyamine can be variously changed depending on the respective molecular weight, 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) 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 copolymer of polyalkylsiloxane and polyether. Examples of suitable silicon surfactants include SH-192 and L5340 (manufactured by Toray Dow Corning Silicone).

  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.

  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 base material sheet used in the present invention preferably has a nitrogen gas transmission rate of 1 × 10 ⁻⁷ [cm ³ / cm ² · s · cm Hg] or less, more preferably 1 × 10 ⁻⁸ [cm ³ / cm ² · s · cmHg] or less. Examples of the forming material satisfying the conditions include polyethylene terephthalate, polypropylene, and polyethylene.

  The thickness of the base sheet is not particularly limited, but it is preferably 0.025 to 0.3 mm from the viewpoint of suppressing the permeability of gas included in the polyurethane foam layer, strength, flexibility, More preferably, it is 0.05-0.2 mm.

  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.

  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 manufacturing method of the lamination sheet of this invention, after apply | coating a cell dispersion | distribution urethane composition on a base material sheet, a release sheet is laminated | stacked on this cell dispersion | distribution urethane composition. Thereafter, the cell-dispersed urethane composition is cured while the thickness is made uniform by the pressing means to form a polyurethane foam layer. By using a release sheet, a skin layer is formed on the surface of the polyurethane foam layer.

The release sheet to be used must have a nitrogen gas permeation rate of 1 × 10 ⁻⁷ [cm ³ / cm ² · s · cm Hg] or less, and preferably 1 × 10 ⁻⁸ [cm ³ / cm ^2]. · S · cmHg] or less. Examples of the forming material satisfying the conditions include polyethylene terephthalate, polypropylene, and polyethylene. The release sheet preferably has a small dimensional change due to heat. Further, the surface of the release sheet may be subjected to a release treatment. Moreover, you may use a release sheet as a protective sheet as it is, without peeling after manufacture of a lamination sheet.

  Although the thickness of the release sheet is not particularly limited, it is preferably 0.025 to 0.3 mm from the viewpoint of suppressing the permeability of gas contained in the polyurethane foam layer, strength, flexibility, More preferably, it is 0.05-0.2 mm.

  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-curing has the effect of improving the physical properties of the polyurethane foam and is very suitable. 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.

  The thickness of the polyurethane foam layer is not particularly limited, but is preferably 0.2 to 1.2 mm, and more preferably 0.6 to 1 mm.

  The polyurethane foam layer produced by the above method mainly has an open cell structure, and the open cell rate is 50% or more, preferably 65% or more.

  The average cell diameter of the bubbles in the polyurethane foam layer is preferably 20 to 300 μm, more preferably 50 to 150 μm. When deviating from this range, the surface smoothness of the polished material after polishing tends to deteriorate.

  The specific gravity of the polyurethane foam layer is preferably 0.2 to 0.5, more preferably 0.25 to 0.4. 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 0.5, it is necessary to make the material have a low crosslinking density in order to obtain a certain elastic modulus. In that case, permanent set increases and durability tends to deteriorate.

  The hardness of the polyurethane foam layer is preferably 10 to 50 degrees in terms of Asker C hardness, more preferably 15 to 35 degrees. When the Asker C hardness is less than 10 degrees, the durability 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, the retainability of the material to be polished tends to deteriorate.

  The compression ratio of the polyurethane foam layer is preferably 2 to 10%, more preferably 4 to 8%. When the compression rate is less than 2%, the retention of the material to be polished is deteriorated, and when the compression rate exceeds 10%, the durability and the surface smoothness of the material to be polished after polishing tend to be deteriorated. is there.

  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. The laminated sheet obtained by the production method of the present invention can be used without buffing the holding surface with a separate abrasive because the surface accuracy of the holding surface is extremely high, but even if buffed if necessary Good.

  The laminated sheet of the present invention has a high surface accuracy of the holding surface and the skin layer itself has adhesiveness, so that the material to be polished can be sufficiently held, but an adhesive layer may be provided separately.

  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 and evaluation methods]
(Measurement of nitrogen gas transmission rate)
The nitrogen gas permeation rate [cm ³ / cm ² · s · cmHg] of the base material sheet and the release sheet was measured according to ASTM-D-1434. Specifically, it was measured by the following method. A base sheet and a release sheet were cut into a size of 12 cmφ to prepare a sample. The sample was sandwiched between two plates having a gas permeation area of 10 cmφ, a pressure difference was applied to both surfaces of the sample, and the nitrogen gas permeation rate was calculated from the gradient of the change in nitrogen gas permeation volume at 25 ° C with respect to time. However, the pressure difference was 0.5 MPa when the sample was resin, and the pressure difference was 0.3 MPa when the sample was paper.
(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 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.) for the obtained image, the total bubble diameter in an arbitrary range was measured, and the average bubble 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. The measuring instrument used was an air comparison type hydrometer 930 type (manufactured by Beckman Co., Ltd.). 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 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, which was allowed to stand for 16 hours in an environment of a temperature of 23 ° C. ± 2 ° C. and a humidity of 50% ± 5%. The specific gravity was measured using a hydrometer (manufactured by Sartorius).

(Measurement of hardness)
This was performed according to JIS K-7312. The produced polyurethane foam layer was cut into a size of 5 cm × 5 cm (thickness: arbitrary) and used as a sample. 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.

(Measurement of compression rate)
A polyurethane foam layer cut into a 7 mm diameter circle (thickness: arbitrary) was used as a sample and allowed to stand for 40 hours in an environment of a temperature of 23 ° C. ± 2 ° C. and a humidity of 50% ± 5%. For the measurement, a compression ratio was measured using a thermal analysis measuring instrument TMA (manufactured by SEIKO INSTRUMENTS, SS6000). The calculation formula of the compression rate is shown below.
Compression rate (%) = {(T1-T2) / T1} × 100
T1: Thickness of the polyurethane foam layer when a stress of 4.9 kPa (50 g / cm ² ) is applied to the polyurethane foam layer from an unloaded state and held for 60 seconds.
T2: The thickness of the polyurethane foam layer when a stress of 29.4 kPa (300 g / cm ² ) is applied from the state of T1 and held for 60 seconds.

(Evaluation of adsorptivity)
A glass plate having a smooth surface (50 mmφ × 10 mm thickness) is suspended by a load sensor through a universal joint and is applied at a pressure of 150 g / cm ² on a laminated sheet (□ 80 mm) affixed to a support plate. Adsorbed for 2 seconds. Thereafter, the glass plate was pulled upward at a constant speed (tensile speed: 200 mm / min), and the peel strength (kPa) when the glass plate peeled from the laminated sheet was measured.

(Evaluation of surface accuracy)
The surface accuracy (10-point average roughness: Rz) of the produced polyurethane foam layer was measured under the following conditions using a surface roughness measuring device P-15 manufactured by KLA-Tencor.
Measurement length: 800μm
Measurement speed: 20 μm / s
Measurement load: 2mg

Example 1
High-molecular-weight polyol EX-5030 (Asahi Glass Co., Ltd., OHV: 33, functional group number: 3) 60 parts by weight, polycaprolactone triol (manufactured by Daicel Chemical Industries, Plaxel 305, OHV: 305, functional group number: 3) 40 parts by weight, 5 parts by weight of a silicon-based surfactant (SH-192, manufactured by Toray Dow Corning Silicone) and 0.18 parts by weight of a catalyst (No. 25, manufactured by Kao) are added and mixed to obtain a second. Ingredients (25 ° C.) were prepared. In addition, an average hydroxyl value (OHVav) is 141.8 mgKOH / g (calculated value), and an average functional group number (fav) is 3 (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, 40.3 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 made into a base material sheet (polyethylene terephthalate, manufactured by Toyobo Co., Ltd., Toyobo Ester E5001, thickness: 0.188 mm, nitrogen gas transmission rate: 3.72 × 10 ⁻¹¹ [cm ³ / cm ² · S · cmHg]) to form a cell-dispersed urethane layer. Then, a release sheet (polyethylene terephthalate, manufactured by Toyobo Co., Ltd., Toyobo Ester E7002, thickness: 0.05 mm, nitrogen gas permeation rate: 1.15 × 10 ⁻¹⁰ [released on the cell-dispersed urethane layer] cm ³ / cm ² · s · cmHg]). 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. A skin layer was formed on the polyurethane foam layer. 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
Instead of the release sheet described in Example 1, a release sheet (polypropylene, manufactured by Toyobo Co., Ltd., Toyopearl-SS P4256, thickness: 0.05 mm, nitrogen gas transmission rate: 2.33 × 10 ⁻⁹ [ cm ³ / cm ² · s · cmHg]) was used to produce a laminated sheet in the same manner as in Example 1. 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
Instead of the release sheet described in Example 1, a release sheet (manufactured by Oji Paper, Separator 70GS, thickness: 0.058 mm, nitrogen gas transmission rate: 1.06 × 10 ⁻⁶ [cm ³ / cm ² · s · cmHg]) was used to produce a laminated sheet in the same manner as in Example 1. 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.

It turns out that the laminated sheet of an Example is excellent in adsorptivity since surface precision is very high. On the other hand, it can be seen that the laminated sheet of the comparative example has low surface accuracy and poor adsorptivity.

Claims (8)

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 sheet, and a nitrogen gas transmission rate of 1 × 10 ⁻⁷ [cm ³ / cm ² · s · cmHg] The step of laminating the release sheet which is the following on the applied cell-dispersed urethane composition, the step of forming a polyurethane foam layer having open cells by curing the cell-dispersed urethane composition while making the thickness uniform by pressing means The manufacturing method of the lamination sheet containing this. The method for producing a laminated sheet according to claim 1, wherein the base material sheet has a nitrogen gas permeation rate of 1 × 10 ⁻⁷ [cm ³ / cm ² · s · cmHg] or less. The method for producing a laminated sheet according to claim 1 or 2, wherein the base sheet is a polyethylene terephthalate film, and the release sheet is a polyethylene terephthalate film subjected to a release treatment. The laminated sheet manufactured by the method in any one of Claims 1-3. The laminated sheet according to claim 4, wherein the average cell diameter of the open cells is 20 to 300 µm. The laminated sheet according to claim 4 or 5, wherein the specific gravity of the polyurethane foam layer is 0.2 to 0.5. The laminated sheet according to any one of claims 4 to 6, wherein the polyurethane foam layer has an Asker C hardness of 10 to 50 degrees. The laminate sheet according to any one of claims 4 to 7, wherein the compression ratio of the polyurethane foam layer is 2 to 10%.