JP6180873B2 - Fiber composite sheet, polishing pad and manufacturing method thereof - Google Patents

Description

The present invention relates to a fiber composite sheet that is preferably used as a polishing pad or the like that requires high wear resistance.

  Conventionally, a fiber composite sheet obtained by impregnating a polymer elastic body into an internal space of a nonwoven fabric has been preferably used as a polishing pad or the like used for polishing that requires high-precision flatness. As polishing that requires high-precision flatness, chemical mechanical polishing (CMP) is known in which polishing is performed by pressing a substrate to be polished while dropping a slurry of abrasive grains onto a rotating polishing pad. As a polishing pad used in CMP, Patent Document 1 below discloses a polishing pad in which a non-woven fabric composed of a bundle of ultrafine fibers is impregnated with a polymer elastic body. Such a polishing pad has low rigidity and is flexible compared with a polishing pad of a polyurethane molded body that has been widely used so far, and therefore has excellent followability to the shape of the surface of the substrate to be polished, and therefore has excellent planarization performance. In addition, since the surface of the polishing pad is flexible, it is difficult to apply a force to the aggregate of abrasive grains, so that there is an advantage that it is difficult to generate scratches.

  However, a polishing pad including a nonwoven fabric and a polymer elastic body has a problem that it is easily worn because the surface is soft. As a polishing pad that solves such a problem, Patent Document 2 below includes a nonwoven fabric of ultrafine fibers and a composite of a polymer elastic body and inorganic particles impregnated inside the nonwoven fabric, and the composite is inorganic. Disclosed is a polishing pad comprising 1-50% by weight of particles.

International Publication 2010/016486 Pamphlet JP 2012-210683A

The polishing pad disclosed in Patent Document 2 has improved wear resistance by arranging inorganic particles having high hardness on the polishing surface. However, in such a polishing pad, there is a possibility that inorganic particles fall off during polishing.
An object of the present invention is to provide a fiber composite sheet having high wear resistance, which is preferably used as a polishing pad or the like that requires high wear resistance.

The fiber composite sheet according to the present invention includes a nonwoven fabric and a polymer elastic body imparted to the internal voids of the nonwoven fabric, and has a thickness of 0.5 to 1.5 mm. The nonwoven fabric has an apparent density of 0.5 g / It is an entangled body of fiber bundles of long fibers of ultrafine fibers having a fineness of 0.5 dtex or less that are not less than cm ³ , and the porosity of the surface layer part that is a thickness region of 50 μm from both sides is V _S , with respect to the total thickness continuous to the surface part V _S / V _m ≦ 0.86 and arithmetic average surface roughness (Ra), where V _m is the porosity of the middle layer portion that is the region (thickness region excluding the thickness of 50 μm from both sides) Has a surface having a JIS-C hardness of 75 to 90 with a thickness of 15 μm or less. According to such a configuration, an entangled body of fiber bundles of ultrafine fibers having a fineness of 0.5 dtex or less, containing a dense nonwoven fabric having a high fiber density and an apparent density of 0.5 g / cm ³ or more, and a polymer elastic body In addition, because it has a composite layer of polymer elastic body and nonwoven fabric with a low porosity on the surface layer, it maintains high rigidity due to the reinforcing effect of the fiber bundle and realizes high wear resistance by having high surface hardness it can. In addition, by suppressing surface spots due to the presence of voids in the surface layer, high planarization performance can be obtained when used for a polishing pad.

Moreover, the manufacturing method of the fiber composite sheet which concerns on this invention is a method of manufacturing the fiber composite sheet mentioned above, Comprising: The fiber which consists of a sea-island type composite fiber for forming the ultrafine fiber of a long fiber with a fineness of 0.5 dtex or less A step of producing a web, a step of obtaining an entangled fiber sheet by entanglement treatment of a fiber web, a step of obtaining a entangled fiber sheet densified by subjecting the entangled fiber sheet to heat shrinkage, and a dense A step of coagulating the polymer elastic body after selectively applying the aqueous polymer liquid containing the thermosensitive gelling agent to the entangled fiber sheet and selectively removing the sea component of the sea-island type composite fiber Forming a non-woven fabric that is an entangled body of ultrafine fiber bundles, washing the thermosensitive gelling agent with water, and further applying an aqueous polymer elastic liquid to the non-woven fabric, so that a thickness region of 125 μm from both sides is obtained. Porosity V _a, when the porosity of the middle layer portion is a region to the total thickness (thickness area excluding the thickness of 125μm from both sides) was V _b, so that V _a / V _b ≦ 0.9 Surface to which V _S / V _m ≦ 0.86, arithmetic mean surface roughness (Ra) is 15 μm or less, and JIS-C hardness is 75 to 90 by grinding the surface and adjusting step Forming a step.

  In the production method as described above, the polymer elastic body is obtained by coagulating the polymer elastic body after applying the polymer elastic body aqueous liquid containing the thermosensitive gelling agent to the densified entangled fiber sheet. Suppresses migration unevenly distributed on the surface layer. Then, by filling the gap between the ultrafine fibers of the fiber bundle formed by the ultrafine fiber processing of the sea-island type composite fiber with the polymer elastic body, the ultrafine fibers constituting the fiber bundle are converged and the fiber bundles are also Be bound. At this time, by filling the surface with a polymer elastic body and adjusting the amount of grinding of the surface at the time of adjusting the thickness, the voids in the vicinity of the surface that becomes the polishing surface can be further reduced. As a result, a high hardness surface with high hardness and suppressed surface spots is formed. Further, by grinding the surface roughness (Ra) to 15 μm or less, a fiber composite sheet having high wear resistance can be obtained.

  The fiber composite sheet obtained by the present invention can achieve high wear resistance as required for a polishing pad material, for example, in a fiber composite sheet in which a polymer elastic body is applied to the internal voids of a nonwoven fabric.

FIG. 1 is a schematic cross-sectional view of a cross-section in the thickness direction of a polishing pad material according to an embodiment of the present invention.

  The fiber composite sheet according to the present invention is a fiber composite sheet in which a polymer elastic body is imparted to the internal voids of a nonwoven fabric, and has high wear resistance. Therefore, it is preferably used for applications such as a polishing pad material that requires high wear resistance and a decorative sheet material that decorates the surface of an article. In this embodiment, the polishing pad material using such a fiber composite sheet will be described in detail as a representative example.

One embodiment of the fiber composite sheet of this embodiment will be described with reference to FIG. A fiber composite sheet 10 of this embodiment shown in FIG. 1 includes a nonwoven fabric 1 and a polymer elastic body 2 imparted to the internal space of the nonwoven fabric 1, and has a thickness of 0.5 to 1.5 mm. The nonwoven fabric 1 is an entangled body of fiber bundles 1b of ultrafine fibers 1a of long fibers having an apparent density of 0.5 g / cm ³ or more and a fineness of 0.5 dtex or less. Then, is the region to the total thickness leading to the surface layer portion L _S and the surface layer portion from both sides is a 50μm thick region of the fiber composite sheet 10 to be polishing surface of the polishing pad material (thickness regions excluding the thickness of 50μm from both sides) including a middle layer L _m. The fiber composite sheet 10 has a void V unfilled, the porosity V _S of the surface layer portion L _S, the porosity of the middle layer portion L _m the case of a _{V m, V S / V m} ≦ 0. 86. Further, the surface to be a polished surface has a surface having an arithmetic average surface roughness (Ra) of 15 μm or less and a JIS-C hardness of 75 to 90.

The nonwoven fabric in this embodiment is an entangled fiber bundle of ultrafine fibers of long fibers having an apparent density of 0.5 g / cm ³ or more and a fineness of 0.5 dtex or less.

  The fineness of the ultrafine fiber is 0.5 dtex or less, preferably 0.0001 to 0.5 dtex, and more preferably 0.001 to 0.1 dtex. When the fineness of the ultrafine fiber exceeds 0.5 dtex, the polishing rate decreases because the surface becomes too rough when used as a polishing pad material, and the softness of the surface is lost and the abrasive is agglomerated during polishing. Grain makes it easier to generate scratches. Moreover, when the fineness of the ultrafine fibers is too low, the ultrafine fibers in the vicinity of the polished surface are difficult to be separated, and the retention of the abrasive slurry tends to be reduced.

  The ultrafine fibers and their fiber bundles are long fibers, specifically, 100 mm or more, and further 200 mm or more can increase the fiber density of the fiber composite sheet by increasing the fiber density of the ultrafine fibers. The polishing pad is preferable from the viewpoint that the fiber can be prevented from coming off during polishing. If the lengths of the ultrafine fibers and the fiber bundle are too short, the fibers are likely to come off, the fiber density is difficult to increase, and high rigidity tends not to be obtained. The upper limit of the fiber length is not particularly limited. For example, in the case of a nonwoven fabric produced by a spunbond method described later, it is several meters, several hundreds meters, several kilometers or more unless it is physically cut. May be.

The apparent density of the nonwoven fabric is 0.5 g / cm ³ or more, preferably 0.55 g / cm ³ or more. By adjusting to such a high apparent density, a nonwoven fabric having a high fiber density is formed, and a fiber composite sheet having a high rigidity is obtained. The upper limit is not particularly limited, but is preferably 1.0 g / cm ³ or less from the viewpoint of excellent productivity.

As the cross-sectional area of the fiber bundle existing in the cross section in the thickness direction of the fiber composite sheet, the fiber bundle having a cross-sectional area of an average cross-sectional area of 40 μm ² or more is 25 with respect to the total number of fiber bundles observed in the unit area. % Or more, more preferably 40% or more, particularly 50% or more, in particular 100%. In such a case, when used as a polishing pad material, high planarization performance can be realized as a polishing pad material for silicon wafers, semiconductor wafers, and semiconductor devices.

Moreover, the average cross-sectional area of the fiber bundles present in the cross section in the thickness direction of the fiber composite sheet is 80 μm ² or more, more preferably 100 μm ² or more, particularly 120 μm ² or more. It is preferable from the point obtained. When the average cross-sectional area is too small, the stiffness of the fiber composite sheet tends to be low.

Further, the bundle density of the fiber bundles present in the cross section in the thickness direction of the fiber composite sheet is 600 bundles / mm ² or more, further 1000 bundles / mm ² or more, 4000 bundles / mm ² or less, and 3000 bundles. / Mm ² or less is preferable. In the case of such a fiber bundle density, when used as a polishing pad material, the fiber bundle exposed on the surface of the polishing pad material during polishing is split or fibrillated to form ultrafine fibers, whereby an abrasive slurry And the surface becomes soft, and the occurrence of scratches is easily suppressed. If the fiber bundle density is too low, the fiber density of the ultrafine fibers exposed on the surface of the polishing pad material tends to be low, whereby the polishing rate tends to decrease and the planarization performance tends to decrease. Further, when the fiber bundle density is too high, the surface of the polishing pad material becomes too dense, and the retention of the abrasive slurry tends to decrease, and the polishing rate tends to decrease.

  Specific examples of the resin component forming the ultrafine fiber include, for example, polyethylene terephthalate (PET), isophthalic acid modified PET, sulfoisophthalic acid modified PET, polybutylene naphthalate, polyethylene naphthalate, polyhexamethylene terephthalate, polybutylene terephthalate, Aromatic polyesters and aliphatic polyesters such as polyethylene succinate, polybutylene succinate, polybutylene succinate adipate, polyhydroxybutyrate-polyhydroxyvalerate copolymer, polylactic acid, terephthalic acid, nonanediol, and methyloctanediol Polymerized nylon, nylon 6, nylon 66, nylon 10, nylon 11, nylon 12, and other aliphatic nylons; polyethylene, polypropylene, and other polyolefins; Modified polyvinyl alcohol containing down units 25 to 70 mole%; polyurethane elastomer, nylon type elastomer, and the like elastomers and polyester elastomers. These may be used alone or in combination of two or more.

Among these, a thermoplastic resin having a glass transition temperature (T _g ) of 50 ° C. or more, further 60 ° C. or more and a water absorption of 4% by mass or less, and further 2% by mass or less was used as a polishing pad material. In particular, it is particularly preferable from the viewpoint of excellent stability over time of polishing. If it is less than T _g is 50 ° C. for the thermoplastic resin, it reduces the flattening performance rigidity is insufficient, also, over time the abrasive stability and polishing uniformity rigidity is reduced at the time of polishing to decline There is. Also, when the water absorption rate of the thermoplastic resin exceeds 4% by mass, the fine fibers gradually absorb the moisture in the abrasive slurry during polishing and the rigidity decreases over time, so that it flattens over time. Performance, polishing rate and polishing uniformity tend to decrease.

Specific examples of the thermoplastic resin having a T _g of 50 ° C. or more and a water absorption of 4% by mass or less include, for example, PET (T _g 77 ° C., water absorption of 1% by mass), isophthalic acid-modified PET (T _g 67˜ 77 ° C., water absorption 1 mass%), sulfoisophthalic acid-modified PET (T _g 67-77 ° C., water absorption 1-4 mass%), polybutylene naphthalate (T _g 85 ° C., water absorption 1 mass%), polyethylene Aromatic polyester fiber formed from naphthalate (T _g 124 ° C., water absorption 1 mass%), etc .; terephthalic acid, nonanediol, methyloctanediol copolymer nylon (T _g 125-140 ° C., water absorption 1-4 And a semi-aromatic polyamide-based resin formed from (mass%) and the like. Further, PET, isophthalic acid-modified PET, polybutylene naphthalate, and polyethylene naphthalate are preferable from the viewpoint of particularly excellent rigidity, water resistance, and abrasion resistance of the obtained fiber composite sheet. In addition, PET and isophthalic acid-modified PET can be used as a polishing pad material because a nonwoven fabric with high fiber density can be obtained by forming a very fine fiber from a web-entangled sheet composed of sea-island type composite fibers described later. The rigidity is most preferable, and the change with time due to moisture during polishing is also small, which is most preferable.

  In the fiber composite sheet of the present embodiment, the polymer is formed in the internal space of the nonwoven fabric so that the mass ratio (nonwoven fabric / polymer elastic body) is 90/10 to 55/45, and further 85/15 to 65/35. It is preferable that an elastic body is provided. When the mass ratio of the nonwoven fabric / polymer elastic body is in such a range, the stiffness of the fiber composite sheet is increased, and when used as a polishing pad material, the density of the ultrafine fibers exposed on the surface is increased. , Polishing stability, polishing rate, and planarization performance can be improved.

  Moreover, in the fiber composite sheet of this embodiment, it is preferable that the polymer elastic body exists so as to converge the ultrafine fibers of long fibers forming the fiber bundle. Here, the ultrafine fibers of the long fibers are converged means that the majority of the ultrafine fibers of the long fibers existing inside the fiber bundle are bonded and restrained by the polymer elastic body existing inside the fiber bundle. Means. Since the ultrafine fibers are focused on the polymer elastic body, the rigidity of the fiber composite sheet is increased. When the ultrafine fibers are not converged, the ultrafine fibers are flexible, and therefore, when used as a polishing pad material, the planarization performance tends to be lowered. Further, the fibers are more likely to come off during polishing, and the abrasive grains aggregate on the removed fibers and scratches are likely to occur. Furthermore, it is preferable that the plurality of fiber bundles are bound together by a polymer elastic body existing outside the fiber bundle and exist in a lump (bulk) shape. As described above, the fiber bundles are bound to each other, so that the shape stability is improved and the polishing stability is improved.

  The polymer elastic body in which the ultrafine fibers are bundled and the polymer elastic body in which the fiber bundles are bound to each other are preferably non-porous. The non-porous state means a state substantially free of closed cells, such as a porous or sponge-like (hereinafter also simply referred to as porous) polymer elastic body. . Specifically, it means that it is not a polymer elastic body having many closed cells, for example, obtained by coagulating solvent-based polyurethane. In the case where the polymer elastic body that is focused or bound is non-porous, a fiber composite sheet that is superior in wear resistance can be obtained because high rigidity is obtained. In addition, when used as a polishing pad material, the polishing stability is high, the wear is difficult to wear, and the slurry waste and pad waste at the time of polishing are less likely to accumulate in the gap, so that a high polishing rate is maintained for a long time. Furthermore, since the adhesive strength to the ultrafine fibers is increased, it is possible to suppress the occurrence of scratches at the time of polishing due to the removal of the fibers.

  Specific examples of the polymer elastic body include, for example, a polyurethane resin, a polyamide resin, a (meth) acrylic acid ester resin, a (meth) acrylic acid ester-styrene resin, and a (meth) acrylic acid ester-acrylonitrile resin. , (Meth) acrylic ester-olefin resin, (meth) acrylic ester- (hydrogenated) isoprene resin, (meth) acrylic ester-butadiene resin, styrene-butadiene resin, styrene-hydrogenated isoprene Resin, acrylonitrile-butadiene resin, acrylonitrile-butadiene-styrene resin, vinyl acetate resin, (meth) acrylic acid ester-vinyl acetate resin, ethylene-vinyl acetate resin, ethylene-olefin resin, silicone resin , Fluororesin and polyester Resins. These may be used alone or in combination of two or more. Among these, the polyurethane resin increases the hardness of the fiber composite sheet because it is excellent in adhesiveness for bundling ultrafine fibers and binding fiber bundles, and is used for polishing as a polishing pad material. It is preferable from the viewpoint of excellent temporal stability over time.

  As a polymer elastic body, when a polymer elastic body having a water absorption rate of 0.5 to 8% by mass, further 1 to 6% by mass is used as a polishing pad material, it is particularly excellent in stability over time during polishing. preferable. When the water absorption rate of the polymer elastic body is too low, the wettability of the abrasive slurry with respect to the polishing pad material during polishing decreases, the polishing rate decreases, the polishing uniformity and polishing stability decrease, Abrasive grains tend to aggregate and tend to generate scratches. When the water absorption rate of the polymer elastic body is too high, the polishing rate and polishing uniformity are likely to fluctuate because the rigidity of the polishing pad material decreases with time and the planarization performance decreases during polishing. The water absorption rate of the polymer elastic body is the water absorption rate when the dried polymer elastic body film is immersed in water at room temperature and saturated and swollen. Further, when two or more kinds of polymer elastic bodies are contained, it is theoretically calculated as the sum of values obtained by multiplying the water absorption of each polymer elastic body by the mass fraction.

  A polymer elastic body having such a water absorption rate can be obtained by adjusting the degree of cross-linking of the polymer constituting the polymer elastic body or introducing a hydrophilic functional group. The polymer elastic body has at least one hydrophilic group selected from the group consisting of a carboxyl group, a sulfonic acid group, and a polyalkylene glycol group having 3 or less carbon atoms to adjust water absorption and hydrophilicity. This is preferable because the wettability of the polishing pad material to the abrasive slurry during polishing can be improved. By improving the wettability as described above, the polishing rate, the polishing uniformity, and the polishing stability are improved. Such a hydrophilic group can be introduced into the polymer elastic body by copolymerizing a component having a hydrophilic group as a monomer component for producing the polymer elastic body. The copolymerization ratio of the monomer component having such a hydrophilic group is 0.1 to 20% by mass, and further 0.5 to 10% by mass while minimizing swelling and softening due to water absorption. From the point that water absorption and wettability can be improved. In particular, when a polyurethane-based resin having at least one hydrophilic group selected from the group consisting of a carboxyl group, a sulfonic acid group, and a polyalkylene glycol group having 3 or less carbon atoms is used as a polishing pad material, This is preferable from the viewpoints of rigidity, wettability, and stability over time during polishing.

  Further, as the polymer elastic body, the storage elastic modulus [E ′ (150 ° C., dry)] at 150 ° C. is preferably 0.1 to 100 MPa, and more preferably 1 to 80 MPa. Such an elastic modulus can be obtained by forming a crosslinked structure in the polymer elastic body. When the polymer elastic body has a hydrophilic group, it tends to swell with water and tends to increase the water absorption rate. In such a case, the water absorption rate is also controlled by adjusting the degree of the crosslinked structure. In addition, when two or more kinds of polymer elastic bodies are contained, it is theoretically calculated as the sum of values obtained by multiplying the mass fraction by [E ′ (150 ° C., dry)] of each polymer elastic body.

As shown in FIG. 1, the fiber composite sheet 10 according to the present embodiment has a surface layer portion L _S that is a thickness region of 50 μm from the surface on both sides and a region with respect to the total thickness connected to the surface layer portion (50 μm from both surfaces). V _S / V _m ≦ 0 when the intermediate layer portion L _m is a thickness region excluding the thickness), the porosity of the surface layer portion L _S is V _S , and the porosity of the intermediate layer portion L _m is V _m. .86. In the fiber composite sheet of this embodiment, the fiber bundle is strongly restrained by reducing the voids in the surface layer portion by highly filling the surface layer portion, which is a 50 μm thick region from the surface, with a polymer elastic body. As a result, the surface hardness of the fiber composite sheet can be increased. The relationship between the porosity V _S and the porosity V _m is V _S / V _m ≦ 0.86, V _S / V _m ≦ 0.83, and further V _S / V _m ≦ 0.80. Is preferred. In the case of V _S / V _m > 0.86, the surface layer portion is not highly filled with the polymer elastic body, so that the fiber bundle is not sufficiently reinforced and high surface hardness cannot be obtained.

Porosity V _m porosity V _S and the middle portion L _m of the surface layer portion L _S is, for example, determined as follows. A cross section in the thickness direction of the fiber composite sheet was photographed with a scanning electron microscope at a magnification of 30 times. From the obtained image, the porosity V _S of the surface layer portion and the surface layer portion, which are 50 μm thick regions from both sides of the thickness direction cross section, obtaining continuous porosity V _m of the middle layer, respectively. Specifically, the void ratio of each area is binarized by the dynamic threshold method using the image analysis software Popimaging (manufactured by Digital being kids. Co), and an inscribed circle is drawn in the void. In each region, a drawn inscribed circle area of less than 350 μm ² is regarded as noise and removed, and the total area of the remaining circles is calculated as a void amount. A value obtained by dividing the obtained void amount by the cross-sectional area of each region is defined as a void ratio (V _S , V _m ).

  Such a surface has an arithmetic average surface roughness (Ra) of 15 μm or less, preferably 14 μm or less, and more preferably 13 μm. When Ra exceeds 15 μm, the fiber bundle on the surface is not sufficiently reinforced with the polymer elastic body, and high surface hardness cannot be obtained.

  Furthermore, the JIS-C hardness of the surface is 75 to 95, preferably 76 to 93, and more preferably 77 to 90. When the JIS-C hardness is less than 75, the polishing rate is lowered and the wear resistance of the surface is also lowered. Moreover, when JIS-C hardness exceeds 95, when using as a polishing pad material, it may become difficult to set to a polishing apparatus.

The thickness of the fiber composite sheet of this embodiment is 0.5 to 1.5 mm, preferably 0.8 to 1.4 mm. The apparent density is preferably 0.5 to 1.2 g / cm ³ , and more preferably 0.6 to 1.2 g / cm ³ from the viewpoint of excellent rigidity.

[Production method of fiber composite sheet]
Next, the fiber composite sheet of the present embodiment will be described in more detail along with an example of the manufacturing method thereof.

The fiber composite sheet according to the present embodiment includes, for example, a process of manufacturing a fiber web made of sea-island composite fibers for forming ultrafine fibers of long fibers having a fineness of 0.5 dtex or less, and entanglement of the fiber web. A step of obtaining an entangled fiber sheet, a step of obtaining a entangled fiber sheet densified by subjecting the entangled fiber sheet to heat shrinkage, and a heat-sensitive gelling agent contained in the densified entangled fiber sheet After applying the molecular elastic body aqueous liquid, a step of solidifying the polymer elastic body, and selectively removing the sea component of the sea-island type composite fiber to form a nonwoven fabric that is an entangled fiber bundle of ultrafine fibers, a step of washing the heat-sensitive gelling agent addition, by further imparting elastic polymer aqueous solution to the nonwoven fabric, at least one surface thereof, the void ratio V _a thickness region of 125μm from both sides, both sides The porosity of the area which is an area to the total thickness (thickness area excluding the thickness of 125μm from both sides) communicating with thickness regions Luo 125μm when the V _b, so that V _a / V _b ≦ 0.9 Surface to which V _S / V _m ≦ 0.86, arithmetic mean surface roughness (Ra) is 15 μm or less, and JIS-C hardness is 75 to 90 by grinding the surface and adjusting step The process of forming can be obtained by a manufacturing method provided with.

In the manufacturing method of the present embodiment, first, a fiber web made of sea-island type composite fibers for forming ultrafine fibers of long fibers having a fineness of 0.5 dtex or less is manufactured.

  Sea-island type composite fiber is an island component polymer that is a domain of a different type from the sea component in the sea component polymer that is a matrix in the fiber cross section, and by removing the sea component later, It is a fiber that forms a fiber bundle-like ultrafine fiber mainly composed of an island component polymer.

A fiber web of sea-island type composite fibers is, for example, formed by melting and spinning a sea component thermoplastic resin and an island component thermoplastic resin, and then stretching and then depositing on a net by a spunbond method. Is obtained. By forming a fiber web by such a spunbond method, when used as a polishing pad material, there are few fibers coming off at the time of polishing, fiber density is high, and ultrafine fibers of long fibers with good shape stability are formed. A fiber web made of sea-island type composite fibers is obtained. In addition, you may crimp | bond partially the fiber web deposited as needed. The basis weight of the fiber web thus obtained is not particularly limited, but is preferably in the range of ^{20 to} 500 g / m ² , for example.

  As the resin for forming the island component of the sea-island composite fiber, the above-described resin component that forms the ultrafine fiber is used. Moreover, the island component may contain various additives. Specific examples of additives include, for example, catalysts, anti-coloring agents, heat-resistant agents, flame retardants, lubricants, antifouling agents, fluorescent whitening agents, matting agents, coloring agents, gloss improvers, antistatic agents, and fragrances. , Deodorants, antibacterial agents, acaricides, inorganic fine particles and the like.

  On the other hand, the resin for forming the sea component of the sea-island composite fiber is not particularly limited as long as it is a resin that can be selectively removed later in combination with the island component. Specific examples of the resin for forming such a sea component include, for example, water-soluble thermoplastic resins such as polyvinyl alcohol (PVA) resin, polyethylene oxide, polyethylene, polypropylene, polystyrene, ethylene-propylene copolymer, polyethylene Examples thereof include a modified polyester, an ethylene vinyl acetate copolymer, a styrene ethylene copolymer, and a styrene acrylic copolymer that contain glycol and / or an alkali metal sulfonate as a copolymer component. In these, water-soluble thermoplastic resins, such as PVA-type resin, especially ethylene-modified PVA is preferable from the point which heat shrinks easily. These may be used alone or in combination of two or more.

  Then, a web entangled sheet is formed by overlapping and entangling about 4 to 100 fiber webs. The web entangled sheet is formed by performing an entanglement process on the fiber web using a needle punch, a high-pressure water flow process, or the like. Hereinafter, the entanglement process by the needle punch will be described in detail.

First, a silicone-based oil agent or a mineral oil-based oil agent such as a needle breakage preventing oil agent, an antistatic oil agent, an entanglement improving oil agent, or the like is applied to a stack of long fiber webs stacked to have a predetermined basis weight. Thereafter, an entanglement process is performed in which the fibers are three-dimensionally entangled by needle punching the stack of long fiber webs. By performing the needle punching process, a web entangled sheet having a high fiber density and hardly causing the fiber to come off can be obtained. The basis weight of the web-entangled sheet is appropriately selected according to the target thickness, and specifically, for example, a range of 100 to 1500 g / m ² is preferable from the viewpoint of excellent handleability.

  Next, the fiber entangled sheet is increased in fiber density and degree of entanglement by thermally shrinking the web entangled sheet. Specific examples of the heat shrink treatment include, for example, a method in which the web entangled sheet is continuously brought into contact with water vapor, or water is applied to the web entangled sheet, and then the web entangled sheet is heated by electromagnetic waves such as heated air and infrared rays. Examples include a method of heating the provided water. Further, for the purpose of further densifying the web entangled sheet densified by the heat shrink treatment, fixing the form of the web entangled sheet, smoothing the surface, etc. The fiber density may be increased by performing a hot press treatment.

In the heat shrinking treatment, the web entangled sheet is preferably shrunk so that the area shrinkage rate is 35% or more, and further 40% or more. The area shrinkage rate (%) is
Formula: (Area of the web entangled sheet before the heat shrinking process−Area of the web entangled sheet after the heat shrinking process) / Area of the web entangled sheet before the heat shrinking process × 100
Is calculated by Each area means the average area of the surface area and the back surface area of the web-entangled sheet. The fiber density is sufficiently increased by shrinking at such a high shrinkage rate. The upper limit of the area shrinkage rate is not particularly limited, but is preferably about 80% from the viewpoint of shrinkage limit and processing efficiency.

  As a change in the basis weight of the web-entangled sheet before and after the heat shrinkage treatment, the basis weight after the heat shrinkage treatment is 1.2 times (mass ratio) or more compared to the basis weight before the heat shrinkage treatment. It is preferably 5 times or more, 4 times or less, and more preferably 3 times or less. In addition, the fiber entangled sheet subjected to the heat shrink treatment may be further increased in fiber density by heating rolls or hot pressing at a temperature equal to or higher than the heat deformation temperature of the sea-island composite fibers.

  Next, a polymer elastic body is provided to the web entangled sheet that has been subjected to the heat shrinkage treatment. In addition, in order to obtain the fiber composite sheet of this embodiment, it is preferable to provide a polymer elastic body in each of the pre-process and the post-process of the ultra-fine fiber processing of the sea-island composite fiber described later. Specifically, by applying a polymer elastic body in the pre-process of the ultrafine fiber treatment of the web entangled sheet subjected to the heat shrink treatment, the sea-island type composite fiber is fixed and restrained, thereby performing the ultrafine fiber treatment. The form of the sheet can be stabilized. In addition, the polymer entanglement is also applied to the voids in the fiber bundle formed by removing the sea component by applying the polymer elastic body after the ultra-fine fiber treatment of the web entangled sheet subjected to the heat shrink treatment. Therefore, a fiber composite sheet with higher hardness can be obtained.

  As a method for imparting a polymer elastic body to a heat-shrinkable web entangled sheet, the polymer elastic body is solidified after impregnating the heat-shrinkable web entangled sheet with a resin solution of the polymer elastic body. The method of letting it be mentioned.

  As the resin liquid for the polymer elastic body, it is preferable to use an aqueous liquid of the polymer elastic body from the viewpoint of low environmental load. The aqueous liquid of the polymer elastic body is an aqueous solution in which the component forming the polymer elastic body is dissolved in the aqueous medium, or the aqueous dispersion liquid in which the component forming the polymer elastic body is dispersed in the aqueous medium. The aqueous dispersion includes a suspension dispersion and an emulsion. In addition, an aqueous dispersion is particularly preferable because it has a high concentration, a low viscosity, and an excellent impregnation permeability, so that it can be easily filled. The solid content concentration of the aqueous dispersion of the polymer elastic body is preferably 15% by mass or more, and more preferably 25% by mass or more from the viewpoint of easy filling of the polymer elastic body.

  The method for impregnating the web-entangled sheet subjected to the heat shrink treatment with the aqueous liquid of the polymer elastic body is not particularly limited, and examples thereof include a knife coater, a bar coater, a roll coater, and dipping.

  When the web entangled sheet is impregnated with the aqueous dispersion of the polymer elastic body, the inner layer of the aqueous liquid moves to the surface layer as the aqueous liquid dries from the surface, and the polymer elastic body is ubiquitous on the surface layer. In other words, a so-called migration phenomenon may occur. Such migration is preferably suppressed by adding a migration inhibitor having heat-sensitive gelling property to the aqueous dispersion to achieve high filling. As the heat-sensitive gelling agent, water-soluble monovalent or divalent inorganic salts are preferable from the viewpoint that they can be easily removed by a water washing treatment described later. Specific examples of such inorganic salts include, for example, sodium carbonate, sodium sulfate, ammonium sulfate, calcium chloride, calcium sulfate, calcium nitrate, zinc oxide, zinc chloride, magnesium chloride, potassium chloride, potassium carbonate, sodium nitrate, lead nitrate Etc. The addition ratio of the inorganic salts is preferably about 0.5 to 5 parts by mass with respect to 100 parts by mass of the polymer elastic body, for example. When using an aqueous dispersion of a polymer elastic body containing a heat-sensitive gelling agent, the polymer elastic body is converted into a heat-sensitive gel by heating the inside while suppressing rapid evaporation of moisture from the surface layer by steam heating. Let And the polymer elastic body can be uniformly provided in the thickness direction by drying the heat-gelled polymer elastic body at 150 ° C.

  As the polymer elastic body, a hydrogen-bonding polymer elastic body is preferable because of its high binding property to ultrafine fibers. The hydrogen-bonding polymer elastic body is an elastic body made of a polymer that crystallizes or aggregates by hydrogen bonding, such as polyurethane resin, polyamide resin, polyvinyl alcohol resin, and the like. The hydrogen-bonding polymer elastic body has high adhesiveness, improves the shape retention of the fiber entangled body, and suppresses the fiber from coming off.

  Below, the case where the elastic body which consists of polyurethane-type resin is used as a polymeric elastic body is demonstrated in detail as a representative example.

  Examples of the elastic body made of a polyurethane resin include various polyurethane resins obtained by reacting a polymer polyol having an average molecular weight of 200 to 6000, an organic polyisocyanate, and a chain extender in a predetermined molar ratio. It is done.

  Specific examples of the polymer polyol include, for example, polyether polyols such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, poly (methyltetramethylene glycol), and copolymers thereof; polybutylene adipate diol, polybutylene sebacate Polyester polyols such as diol, polyhexamethylene adipate diol, poly (3-methyl-1,5-pentylene adipate) diol, poly (3-methyl-1,5-pentylene sebacate) diol, polycaprolactone diol, and the like Copolymer thereof; polyhexamethylene carbonate diol, poly (3-methyl-1,5-pentylene carbonate) diol, polypentamethylene carbonate diol, polytetramethylene carbonate Polycarbonate polyols and their copolymers such as Tojioru; polyester carbonate polyols and the like. If necessary, a trifunctional alcohol such as trimethylolpropane and a polyfunctional alcohol such as tetrafunctional alcohol such as pentaerythritol, or ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol. Etc. You may use together short chain alcohols, such as. These may be used alone or in combination of two or more. In particular, the use of amorphous polycarbonate polyols, alicyclic polycarbonate polyols, linear polycarbonate polyols, and mixtures of these polycarbonate polyols with polyether polyols or polyester polyols are resistant to water. This is preferable because a polishing pad material excellent in durability such as decomposability and oxidation resistance can be obtained. A polyurethane-based resin containing a polyalkylene glycol group having 5 or less carbon atoms, particularly 3 or less carbon atoms, is preferable from the viewpoint of particularly good wettability with water.

  Specific examples of the organic polyisocyanate include, for example, non-yellowing diisocyanates such as aliphatic or alicyclic diisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, norbornene diisocyanate, 4,4′-dicyclohexylmethane diisocyanate; 2,4-tri Examples thereof include aromatic diisocyanates such as range isocyanate, 2,6-tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, and xylylene diisocyanate polyurethane. Moreover, you may use together polyfunctional isocyanates, such as trifunctional isocyanate and tetrafunctional isocyanate, as needed. These may be used alone or in combination of two or more. Among these, 4,4′-dicyclohexylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, and xylylene diisocyanate have high adhesion to fibers, Moreover, it is preferable from the point from which the polishing pad material with high hardness is obtained.

  Specific examples of the chain extender include, for example, diamines such as hydrazine, ethylenediamine, propylenediamine, hexamethylenediamine, nonamethylenediamine, xylylenediamine, isophoronediamine, piperazine and derivatives thereof, adipic acid dihydrazide, and isophthalic acid dihydrazide; Triamines such as diethylenetriamine; tetramines such as triethylenetetramine; ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,4-bis (β-hydroxyethoxy) benzene, 1,4 -Diols such as cyclohexanediol; Triols such as trimethylolpropane; Pentaols such as pentaerythritol; Aminoethyl alcohol, Aminopropyl alcohol Which amino alcohols and the like. These may be used alone or in combination of two or more. Among these, it is preferable to use a combination of two or more of hydrazine, piperazine, hexamethylenediamine, isophoronediamine and derivatives thereof, and triamines such as ethylenetriamine from the viewpoint of completing the curing reaction in a short time. In addition, during the chain extension reaction, together with the chain extender, monoamines such as ethylamine, propylamine, and butylamine; carboxyl group-containing monoamine compounds such as 4-aminobutanoic acid and 6-aminohexanoic acid; methanol, ethanol, propanol, butanol, etc. Monools may be used in combination.

  In addition, a polyurethane containing a carboxyl group-containing diol such as 2,2-bis (hydroxymethyl) propionic acid, 2,2-bis (hydroxymethyl) butanoic acid, 2,2-bis (hydroxymethyl) valeric acid, etc. By introducing an ionic group such as a carboxyl group into the skeleton of the elastic body, the wettability to water can be further improved.

  Furthermore, in order to control the water absorption and storage elastic modulus of the polyurethane resin, a crosslinking agent containing two or more functional groups in the molecule that can react with the functional group of the monomer unit forming the polyurethane, A cross-linked structure may be formed by adding a self-crosslinking compound such as a compound or a polyfunctional blocked isocyanate compound.

  The combination of the functional group of the monomer unit and the functional group of the crosslinking agent includes a carboxyl group and an oxazoline group, a carboxyl group and a carbodiimide group, a carboxyl group and an epoxy group, a carboxyl group and a cyclocarbonate group, a carboxyl group and an aziridine group, and a carbonyl group. And hydrazine derivatives and hydrazide derivatives. Among these, a monomer unit having a carboxyl group and a crosslinking agent having an oxazoline group, a carbodiimide group or an epoxy group, a combination of a monomer unit having a hydroxyl group or an amino group and a crosslinking agent having a blocked isocyanate group, and a carbonyl group A combination of a monomer unit having a hydrazine derivative or a hydrazide derivative is particularly preferred from the viewpoint of easy cross-linking and excellent rigidity and wear resistance of the resulting fiber composite sheet. The crosslinked structure is preferably formed in the heat treatment step after applying the polyurethane resin to the fiber entangled body from the viewpoint of maintaining the stability of the aqueous liquid of the polymer elastic body. Among these, a carbodiimide group and / or an oxazoline group are particularly preferable because they are excellent in crosslinking performance and pot life of an aqueous liquid and have no problem in safety. Examples of the crosslinking agent having a carbodiimide group include water-dispersed carbodiimide compounds such as “Carbodilite E-01”, “Carbodilite E-02”, and “Carbodilite V-02” manufactured by Nisshinbo Industries, Ltd. Examples of the crosslinking agent having an oxazoline group include water-dispersed oxazoline compounds such as “Epocross K-2010E”, “Epocross K-2020E”, and “Epocross WS-500” manufactured by Nippon Shokubai Co., Ltd. As a compounding quantity of a crosslinking agent, it is preferable that the active ingredient of a crosslinking agent is 1-20 mass% with respect to a polyurethane-type resin, Furthermore, 1.5-1 mass%, It is especially 2-10 mass%.

  In addition, from the viewpoint of enhancing the adhesion to the ultrafine fibers and increasing the rigidity of the fiber bundle, the content of the component of the polymer polyol in the polyurethane resin is 65% by mass or less, and further 60% by mass or less. Is preferred. Moreover, it is preferable that it is 40 mass% or more, and also 45 mass% or more from the point which can suppress generation | occurrence | production of a scratch when it uses as a polishing pad material by providing moderate elasticity.

  Polyurethane resins are penetrants, antifoaming agents, lubricants, water repellents, oil repellents, thickeners, extenders, curing accelerators, antioxidants, UV absorbers, fluorescent agents, antifungal agents, foaming agents, You may further contain water-soluble high molecular compounds, such as polyvinyl alcohol and carboxymethylcellulose, dye, a pigment, an inorganic fine particle.

  The method for making the polyurethane resin into an aqueous dispersion is not particularly limited, and a known method can be used. Specifically, for example, a method of imparting dispersibility to an aqueous medium to a polyurethane resin by using a monomer having a hydrophilic group such as a carboxyl group, a sulfonic acid group, or a hydroxyl group as a copolymerization component, or A method of emulsifying or suspending a polyurethane resin by adding a surfactant may be mentioned.

  Specific examples of the surfactant used for emulsification or suspension include, for example, sodium lauryl sulfate, ammonium lauryl sulfate, sodium polyoxyethylene tridecyl ether acetate, sodium dodecylbenzene sulfonate, sodium alkyldiphenyl ether disulfonate, dioctyl sulfosuccinic acid Anionic surfactants such as sodium; nonionic properties such as polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene-polyoxypropylene block copolymer Surfactant etc. are mentioned. Moreover, you may use what is called reactive surfactant which has reactivity. Moreover, heat-sensitive gelation property can also be provided to a polyurethane-type resin by selecting suitably the cloud point of surfactant. The dispersion average particle diameter of the aqueous polyurethane resin dispersion is not particularly limited, but is preferably 0.01 to 1 μm, and more preferably 0.03 to 0.5 μm, for example.

  Next, the sea-island type composite fiber in the web entangled sheet subjected to the heat shrink treatment to which the polymer elastic body is applied is subjected to ultrafine fiber treatment to form a nonwoven fabric which is an entangled body of the fiber bundle of ultrafine fibers.

  This step is a step of forming ultrafine fibers by subjecting the sea-island type composite fibers forming the web-entangled sheet subjected to heat shrinkage treatment to ultrafine fibers. Note that voids are formed between the ultrafine fibers by removing sea components from the sea-island composite fibers. In this gap, the ultrafine fibers are focused by being filled with the polymer elastic body in the step of refilling the polymer elastic body described later.

  The sea-island composite fiber in the web-entangled sheet subjected to heat shrink treatment to which a polymer elastic body is applied is obtained by subjecting a thermoplastic resin that forms a sea component by hydrothermal treatment with water, an alkaline aqueous solution, an acidic aqueous solution, or the like. By dissolving and removing or decomposing and removing, ultrafine fibers formed from island component resin are formed. As a specific example of the hot water treatment, for example, as a first stage, after being immersed in hot water at 65 to 90 ° C. for 5 to 300 seconds, further, as a second stage, 100 in hot water at 85 to 100 ° C. The method of processing for ˜600 seconds is mentioned. Moreover, in order to improve dissolution efficiency, you may perform the nip process by a roll, a high pressure water flow process, an ultrasonic process, a shower process, a stirring process, a stagnation process, etc. as needed.

  In addition, when a sea component is melt | dissolved from a sea-island type composite fiber, the ultrafine fiber formed shrinks greatly. This shrinkage increases the fiber density because the fiber density becomes denser. In addition, when the heat-sensitive gelling agent is added to the aqueous liquid of the polymer elastic body, the heat-sensitive gelling agent is also removed by washing in this step.

  Next, the fiber bundle formed from the ultrafine fibers is further filled with a polymer elastic body to focus the ultrafine fibers and bind the fiber bundles. When the above-mentioned sea-island type composite fiber is subjected to ultrafine fiber treatment, voids are formed inside the formed fiber bundle. In this step, by filling the voids with a polymer elastic body, the ultrafine fibers are focused and the void ratio of the fiber composite sheet is reduced. In addition, since the ultrafine fibers form a fiber bundle, the aqueous solution of the polymer elastic body is easily impregnated by capillary action, and the ultrafine fibers are more easily focused. For the method and type of impregnation of the polymer elastic body with the aqueous liquid, the same method and resin as described above are used.

In addition, in the re-application of the polymer elastic body, when the porosity V _{a of} the 125 μm thick region from both surfaces and V _b is the porosity of the region with respect to the total thickness connected to the 125 μm thick region from both surfaces, It is preferable to adjust so that _a / V _b ≦ 0.9. By adjusting in this way, it becomes easy to obtain a fiber composite sheet that satisfies V _S / V _m ≦ 0.86. The amount of the elastic polymer to be re-applied is appropriately adjusted by the amount of application of the elastic polymer prior to treatment thickness and microfine fiber formation, it is preferably about 40 to 120 g / m ^2. When the amount of the polymer elastic body to be reapplied is too small, the amount of the resin existing in the surface layer tends to be small. Further, when the amount of the elastic polymer to be reapplied is too large, it exceeds the amount that can be impregnated, and the economy tends to decrease. The amount of application can be adjusted by appropriately adjusting the conditions of the knife coater, bar coater, or roll coater so that the polymer elastic body is selectively present on the surface layer, or by dip so as to be unevenly distributed on the surface layer. The method of adjusting conditions etc. are mentioned.

In this way, a nonwoven fabric that is an entangled fiber bundle of ultrafine fibers having an apparent density of 0.5 g / cm ³ or more and a fineness of 0.5 dtex or less, and an internal void of the nonwoven fabric are impregnated with a polymer elastic body. An intermediate sheet for producing the applied fiber composite sheet is obtained.

In addition, the intermediate | middle sheet | seat for manufacturing the fiber composite sheet obtained by doing in this way may contain the component which produces the pH change originating in the substance used by the previous manufacturing process. When a component that causes such pH change remains, when used as a polishing pad material, the abrasive grains may aggregate to cause a problem of a decrease in polishing rate or a scratch. Therefore, it is preferable to remove components that cause a pH change from the intermediate sheet by washing the intermediate sheet with water. As a specific example of the water washing method, for example, a method of washing in hot water of 80 ° C. or higher can be mentioned. Further, in order to increase the dissolution efficiency, nip treatment with a roll, high-pressure water flow treatment, ultrasonic treatment, shower treatment, stirring treatment, stagnation treatment, and the like may be performed as necessary. The amount of ions contained in the intermediate sheet thus washed with water is preferably about 400 μg / cm ³ or less.

  And a fiber composite sheet is obtained by performing the finishing process as shown below with respect to such an intermediate sheet.

As the finishing treatment, the surface of the intermediate sheet is ground by grinding. Grinding is performed with sandpaper, needle cloth, diamond or the like. In this case, in order to adjust the relationship between the porosity V _S of the surface layer portion and the porosity V _m of the middle layer portion to V _S / V _m ≦ 0.86, the grinding amount is 50 to 200 μm from the surface of the intermediate sheet. It is preferable to grind in this range. When the amount of grinding is too large, the polymer elastic body existing on the surface layer tends to fall off, and the effect of focusing and reinforcing the ultrafine fibers tends to decrease. Further, when the grinding amount is too small, it is difficult to obtain a smooth surface having an arithmetic average surface roughness (Ra) of 15 μm or less. In order to form such a surface, it is preferable to use fine sandpaper such as # 60 to # 600, further # 80 to # 400, and particularly # 100 to # 320.

  In this way, a fiber composite sheet is manufactured. And when using a fiber composite sheet as a polishing pad material, a post-processing process etc. are further given as needed and used as a polishing pad.

  Examples of post-processing include reverse seal brushing, grooving, hot pressing, and laminating. The reverse seal brushing process is a process of separating the focused ultrafine fibers by applying mechanical frictional force or polishing force to the surface of the fiber composite sheet with sandpaper, needle cloth, diamond or the like. Groove processing is a process of forming grooves, holes such as lattices, concentric circles, and spirals on the polishing surface in order to adjust the retention and discharge of the abrasive slurry. The hot press process is a process for reducing voids contained in the polishing pad material or further increasing the apparent density. The hot press treatment is selected from temperatures at which the ultrafine fibers and the polymer elastic body are not decomposed. For example, a metal roll heated to 160 to 180 ° C. is used and the pressing is performed under a linear pressure of 30 to 100 kg / cm. To be elected. The lamination treatment is a treatment for adjusting the rigidity by laminating the fiber composite sheet on various substrates such as sponge, knitted fabric, woven fabric, nonwoven fabric, rubber, elastic resin film and the like. For example, the planarization performance can be further improved by laminating the fiber composite sheet with an elastic sheet having low hardness. The material of the elastic film and the elastic sponge body includes natural rubber, nitrile rubber, polybutadiene rubber, as well as non-woven fabrics impregnated with polyurethane (for example, “Suba400” (manufactured by Nitta Haas Co., Ltd.)). Rubbers such as silicone rubber; Thermoplastic elastomers such as polyester-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, and fluorine-based thermoplastic elastomers; foamed plastics; polyurethane and the like can be employed. Moreover, it is good also as a polishing pad material by which the polishing layer containing a fiber composite sheet and the elastic body layer whose hardness is lower than this polishing layer were laminated | stacked. This tends to improve local planarization performance (local planarization performance) on the material to be polished. In addition, the polishing pad material subjected to the lamination treatment is one in which the polishing pad material and the elastic body layer are directly bonded by fusion bonding or the like, in which both layers are bonded by an adhesive or a double-sided adhesive tape, Also included are those in which another layer is present between both layers.

  The polishing pad material obtained by using the fiber composite sheet of the present embodiment includes wafers (silicon wafers, compound semiconductor wafers, etc.), liquid crystal / display members (LED substrates, glass substrates), glass products, metal products, plastic products, Ceramic products, crystal, MEMS (micro-electro-mechanical systems), other substrates (hard disk substrate, metal substrate, plastic substrate, ceramic substrate, optical substrate, electronic circuit substrate, electronic circuit mask substrate, multilayer wiring substrate, hard disk substrate, etc. It is preferably used as a polishing pad used for CMP or the like for polishing various substrates to be polished.

  Hereinafter, the present invention will be specifically described by way of examples. In addition, this invention is not limited at all by the Example.

  First, the evaluation methods used in this example are summarized below.

<Measurement of porosity V _{S of} surface layer portion, porosity V _m of middle layer portion and calculation of V _S / V _m >
The cross section of the obtained fiber composite sheet was observed with a scanning electron microscope at a magnification of 30 times, and a photograph was taken. From the resulting photograph, middle portion is a region to the total thickness leading to porosity V _S and the surface layer portion of the surface layer portion is a double-sided from 50μm thick region of the polishing pad material (thickness regions excluding the thickness of 50μm from both sides) The porosity V _m of each was determined. Specifically, the void ratio of each area is binarized by the dynamic threshold method using the image analysis software Popimaging (manufactured by Digital being kids. Co), and an inscribed circle is drawn in the void. In each region, a drawn inscribed circle area of less than 350 μm ² was regarded as noise and removed, and the total area of the remaining circles was calculated as a void amount. A value obtained by dividing the obtained void amount by the cross-sectional area of each region was defined as a void ratio (V _S , V _m ). Further, V _S / V _m was determined.

<Measurement of Va and V / _Vb of Va in Vapor _Vb of Intermediate Layer and Vapor _Vb of Intermediate Layer>
The cross section of the intermediate of the fiber composite sheet material after re-application of the polymer elastic body and before grinding was observed with a scanning electron microscope at a magnification of 30 times, and a photograph was taken. From the obtained photograph, the porosity V _b in the 125 μm thickness region from both sides and the porosity V _b in the middle layer region, which is a region (thickness region excluding the 125 μm thickness from the surface on both sides) with respect to the total thickness connected to the region. were respectively determined in the same manner as in "porosity V _S of the surface layer portion, the calculation of the measured and V _S / V _m porosity V _m of the middle part". Further, V _a / V _b was obtained.

<Apparent density>
The value obtained by dividing the mass per unit area (g / cm ² ) by the thickness (cm) was used as the apparent density (g / cm ³ ), and the value was obtained by arithmetically averaging the values at any 10 locations. The thickness was measured at a load of 240 gf / cm ² according to JISL1096.

<Surface roughness measurement>
After depositing gold on the surface of the fiber composite sheet, VertScan (Ryoka System Co., Ltd.) was used to measure the uneven height in the range of 1 cm × 1 cm, and the arithmetic average surface roughness (Ra) was determined.

<surface hardness>
The surface hardness was measured according to JIS K 6301.

<Wear loss (Taber wear)>
According to JIS L1096, CS-10 was used as a wear ring, and the load loss was measured under conditions of a load of 500 g and 1000 times, and the wear loss before and after the measurement was measured.

[Example 1]
Water-soluble thermoplastic polyvinyl alcohol-based resin (PVA; sea component) and isophthalic acid-modified polyethylene terephthalate (island component) having a modification degree of 6 mol%, sea component / island component being 25/75 (mass ratio) It was discharged from a die for melt composite spinning (number of islands: 25 islands / fiber) at 260 ° C. The ejector pressure was adjusted so that the spinning speed was 3700 m / min, and long fibers having an average fineness of 3.0 dtex were collected on a net to obtain a spunbond sheet (fiber web) having a basis weight of 35 g / m ² .

12 sheets of the obtained fiber webs were stacked by cross-wrapping so that the total basis weight was 480 g / m ² to obtain a stack, and a needle breakage preventing oil was sprayed. Next, the stacked body is entangled by needle punching at 3075 punches / cm ² using a needle with 42 barbs and needle number 42 with 6 barbs and needle number 42 with 6 barbs. A web entangled sheet was obtained. The obtained web entangled sheet had a basis weight of 540 g / m ² and an interlayer peeling force of 8.8 kg / 2.5 cm. Moreover, the area shrinkage rate by the needle punch process was 32%.

Next, the obtained web-entangled sheet was steam-treated for 65 seconds at 110 ° C. and 23.5% RH. The area shrinkage rate at this time was 48%. And after drying in 90-110 degreeC oven, by further heat-pressing at 115 degreeC, basis weight 986g / m < ² > , apparent density 0 . A web entangled sheet having a thermal shrinkage of 524 g / cm ³ and a thickness of 1.88 mm was obtained.

Next, an emulsion of polyurethane elastic body (solid content 30%) was impregnated with pick up 60% in the web entangled sheet subjected to the heat shrinkage treatment. The polyurethane elastic body is a polycarbonate non-yellowing resin. Furthermore, 4.9 parts by mass of a carbodiimide-based crosslinking agent and 6.4 parts of ammonium sulfate as a heat-sensitive gelling agent were added to 100 parts by mass of the polyurethane elastic body, and the solid content of the polyurethane elastic body was adjusted to 16%. The polyurethane elastic body forms a crosslinked structure by heat treatment. Then, the heat entangled web-entangled sheet impregnated with the emulsion was dried in an atmosphere of 110 ° C. and 30% RH, and further dried at 150 ° C. In this way, the basis weight is 1054 g / m ² , the apparent density is 0 . A sheet having a thickness of 694 g / cm ³ and a thickness of 1.52 mm was obtained.

Next, the PVA and the heat-sensitive gelling agent are obtained by immersing the web entangled sheet filled with the polyurethane elastic body in 95 ° C. hot water for 10 minutes while performing nip treatment and high-pressure water flow treatment. By dissolving and removing and further drying, the single fiber fineness is 0.09 dtex, the basis weight is 750 g / m ² , the apparent density is 0 . A composite of a polyurethane elastic body and a nonwoven fabric that is an entanglement of a fiber bundle of long fibers of ultrafine fibers having a thickness of 529 g / cm ³ and a thickness of 1.42 mm was obtained.

Next, the obtained composite was impregnated again with 91 g / m ² of the same polyurethane elastic emulsion. In that case, 5.0 mass parts of carbodiimide type crosslinking agents were added to the emulsion with respect to 100 mass parts of polyurethane elastic bodies, and it adjusted so that the solid content of a polyurethane elastic body might be 20%. Next, the composite impregnated with the emulsion was treated at 110 ° C. in a 30% RH atmosphere, and an intermediate sheet dried at 150 ° C. was obtained. The obtained intermediate sheet has a basis weight of 833 g / m ² , an apparent density of 0 . The thickness was 573 g / cm ³ and the thickness was 1.46 mm. In addition, the porosity of the 125 μm thick region from both sides is V _a , and the porosity of the middle layer region which is a region (thickness region excluding 125 μm thickness from the surface on both sides) with respect to the total thickness connected to the surface layer portion is V _b . In this case, V _a / V _b = 0.848.

Next, by using # 240 paper and # 320 paper, both sides were ground by 150 μm under conditions of a speed of 3.0 m / min and a rotation speed of 650 rpm, so that the basis weight was 715 g / m ² and the apparent density was 0 . A fiber composite sheet having a thickness of 629 g / cm ³ and a thickness of 1.14 mm was obtained. Further, the porosity of the surface layer portion which is a 50 μm thick region from both surfaces of this fiber composite sheet is V _S , and the void in the middle layer portion which is a region (thickness region excluding the thickness of 50 μm from both surfaces) connected to the surface layer portion. When the rate was V _m , V _S / V _m = 0.733. Moreover, arithmetic mean surface roughness (Ra) was 5.1 micrometers on both surfaces, and JIS-C hardness was 86. The wear loss on the surface was 0 mg. The results are shown in Table 1.

[Example 2]
Instead the amount of re-applying the polyurethane elastomer to 91g / m ^2, to obtain an intermediate sheet except that the 79 g / m ² in the same manner as in Example 1. The obtained intermediate sheet has a basis weight of 820 g / m ² , an apparent density of 0 . The thickness was 561 g / cm ³ and the thickness was 1.46 mm. In addition, when the porosity of the 125 μm thick region from both sides is V _a and the porosity of the middle layer portion, which is a region (thickness region excluding the thickness of 50 μm from both sides) connected to the surface layer portion, is V _b , V _a / V _b = 0.86. Then, in the same manner as in Example 1, by grinding both surfaces of the intermediate sheet, the basis weight 714 g / m ² , the apparent density 0 . A fiber composite sheet having a thickness of 627 g / cm ³ and a thickness of 1.14 mm was obtained. The porosity V _S of the surface layer portion of this fiber composite sheet was 27%, the porosity V _m of the middle layer portion was 35.2%, and V _S / V _m = 0.767. Moreover, arithmetic mean surface roughness (Ra) was 4.9 micrometers and JIS-C hardness was 85. The wear loss on the surface was 0 mg. The results are shown in Table 1.

[Example 3]
Instead of grinding the intermediate sheet obtained in Example 1 using # 240 paper and # 320 paper, the basis weight is 685 g / m ² in the same manner as in Example 1 except that it is ground using # 180 paper. density 0.608 g / cm ^3, to obtain a fiber composite sheet is thickness 1.13 m m. The porosity V _S of the surface layer portion of this fiber composite sheet was 29.2%, the porosity V _m of the middle layer portion was 34.3%, and V _S / V _m = 0.851. The arithmetic average surface roughness (Ra) was 9.7 μm, and the JIS-C hardness was 80. The wear loss on the surface was 0 mg. The results are shown in Table 1.

[Comparative Example 1]
Instead the amount of re-applying the polyurethane elastomer to 91g / m ^2, to give the intermediate sheet except for using 31 g / m ² in the same manner as in Example 1. The obtained intermediate sheet has a basis weight of 849 g / m ² , an apparent density of 0 . The thickness was 594 g / cm ³ and the thickness was 1.43 mm. In addition, when the porosity of the 125 μm thick region from both sides is V _a , and the porosity of the middle layer which is the region (thickness region excluding the 125 μm thickness from both sides) connected to the surface layer portion is V _b , V _a / V _b = 0.985. Then, in the same manner as in Example 1, by grinding both surfaces of the intermediate sheet, the basis weight is 696 g / m ² , the apparent density is 0 . A fiber composite sheet having a thickness of 605 g / cm ³ and a thickness of 1.15 mm was obtained. The porosity V _S of the surface layer portion of this fiber composite sheet was 31.1%, the porosity V _m of the middle layer portion was 32.0%, and V _S / V _m = 0.972. The JIS-C hardness was 73, and the arithmetic average surface roughness (Ra) could not be measured because the fluff was long and rough. Further, the wear loss on this surface was 73 mg. The results are shown in Table 1.

[Comparative Example 2]
The intermediate sheet obtained in Example 1 was used in the same manner as in Example 1 except that # 240 paper and # 320 paper were used and both sides were ground by 150 μm instead of grinding each side by 150 μm. m ² , apparent density 0 . A fiber composite sheet having a thickness of 609 g / cm ³ and a thickness of 0.84 mm was obtained. The porosity V _S of the surface layer portion of this fiber composite sheet was 30.2%, the porosity V _m of the middle layer portion was 34.0%, and V _S / V _m = 0.888. The arithmetic average surface roughness (Ra) was 7.1 μm, and the JIS-C hardness was 81. The wear loss on this surface was 20 mg. The results are shown in Table 1.

[Comparative Example 3]
Instead of grinding the intermediate sheet obtained in Example 2 using # 240 paper and # 320 paper, the basis weight is 641 g / m ² in the same manner as in Example 2 except that it is ground using # 60 paper. Density 0 . A fiber composite sheet having a thickness of 557 g / cm ³ and a thickness of 1.15 mm was obtained. The porosity V _S of the surface layer portion of this fiber composite sheet was 30.4%, the porosity V _m of the middle layer portion was 34.5%, and V _S / V _m = 0.881. Moreover, arithmetic mean surface roughness (Ra) was 18.4 micrometers and JIS-C hardness was 74. Further, the wear loss on this surface was 6.3 mg. The results are shown in Table 1.

  Since the fiber composite sheet obtained in the present invention is excellent in abrasion resistance, it is a polishing pad for polishing semiconductor wafers, semiconductor devices, silicon wafers, hard disks, glass substrates, optical products, or various metals. In addition, it is used as a decorative skin material for articles that require wear resistance.

DESCRIPTION OF SYMBOLS 1 Nonwoven fabric 1a Extra fine fiber 1b Fiber bundle 2 Polymer elastic body 10 Fiber composite sheet v Gap

Claims (5)

A fiber composite sheet having a thickness of 0.5 to 1.5 mm including a nonwoven fabric and a polymer elastic body imparted to the internal voids of the nonwoven fabric,
The non-woven fabric is an entangled fiber bundle of ultrafine fibers having an apparent density of 0.5 g / cm ³ or more and a fineness of 0.5 dtex or less,
The porosity of the surface layer portion, which is a 50 μm thick region from both surfaces, is V _S , and the porosity of the middle layer portion, which is the region (thickness region excluding the thickness of 50 μm from both surfaces) connected to the surface layer portion, is V _m . In some cases, the fiber composite sheet has a surface with V _S / V _m ≦ 0.86, an arithmetic average surface roughness (Ra) of 15 μm or less, and a JIS C hardness of 75 to 90.   The fiber composite sheet according to claim 1, wherein the polymer elastic body is non-porous, and a plurality of the ultrafine fibers forming the fiber bundle are bundled.   The fiber composite sheet according to claim 1 or 2, wherein a mass ratio (nonwoven fabric / polymer elastic body) of the nonwoven fabric and the polymer elastic body is 90/10 to 55/45.   A polishing pad material comprising the fiber composite sheet according to claim 1. A method for producing the fiber composite sheet according to claim 1,
Producing a fiber web comprising sea-island type composite fibers for forming ultrafine fibers of long fibers having a fineness of 0.5 dtex or less;
Obtaining an entangled fiber sheet by entanglement of the fiber web;
Obtaining a entangled fiber sheet densified by heat shrinking the entangled fiber sheet to an area shrinkage of 35% or more;
A step of solidifying the polymer elastic body after applying the polymer elastic body aqueous liquid containing the thermosensitive gelling agent to the densified entangled fiber sheet;
Forming a non-woven fabric which is an entangled fiber bundle of ultrafine fibers by selectively removing sea components of the sea-island composite fibers, and further washing the heat-sensitive gelling agent with water;
By further applying an aqueous polymer elastic liquid to the nonwoven fabric, the porosity V _a of the 125 μm thick region from both sides, the region with respect to the total thickness connected to the surface layer part (thickness region excluding the 125 μm thickness from both sides) A step of adjusting so that V _a / V _b ≦ 0.9, where V _b is the porosity of the middle layer region,
Grinding the surface to form a surface with V _S / V _m ≦ 0.86, an arithmetic average surface roughness (Ra) of 15 μm or less, and a JIS C hardness of 75 to 90; The manufacturing method of the fiber composite sheet characterized by including this.

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