CN105008614A - Rigid sheet and process for manufacturing rigid sheet - Google Patents

Abstract

The invention provides a rigid sheet which comprises both a nonwoven fabric made of ultrafine fibers and a polymeric elastomer applied to the nonwoven fabric, exhibiting a JIS-D hardness of 45 or more, an R% of 0 to 20%, and a total content of ions causing a change in the pH of water of 400[mu]g/cm3 or less. The R% is calculated from six D hardness values according to the formula: R(%)=(maximum D hardness value - minimum D hardness value)/average D hardness value 100. The six D hardness values are determined by: dividing the thicknesswise cross section of the sheet equally into three layers; taking the layers as a first surface layer, an intermediate layer and a second surface layer respectively from one surface side of the sheet; and measuring JIS-D hardness at three arbitrary points in each of the first surface and intermediate layers.

Description

The manufacture method of hard sheet and hard sheet

Technical field

The present invention relates to a kind of hard sheet, it preferably uses as the polishing layer of polishing pad, specifically, preferably use as the polishing layer being used for carrying out semiconductor wafer, semiconductor devices, silicon wafer, hard disk, glass substrate, optical goods or various metals etc. the polishing pad of polishing.

Background technology

The integrated circuit formed in semiconductor wafer is highly integrated and laminates linearize.For such semiconductor wafer, require that there is high flatness.

As the finishing method for polishing of semiconductor wafers, there will be a known chemically mechanical polishing (CMP).CMP is while drip the polishing slurries (following, also referred to as slurry) containing abrasive grains, the method for with polishing pad, polished substrate surface being carried out to polishing.

Following patent document 1 ~ 4 discloses the polishing pad be made up of the foam polymer precursor with hole-closing structure for CMP.Bi-component curable polyurethane is carried out pouring foaming formation and manufactures by foam polymer precursor.Its rigidity of the polishing pad manufactured by foam polymer precursor is more padded than the polishing of non-woven fabric type described later.Therefore, the polishing of the semiconductor wafer requiring high flatness is preferred for.

The rigidity of the polishing pad formed by foam polymer precursor is high.Therefore, optionally load is applied to the protuberance of polished base material.Its result, can obtain higher polishing velocity.But when the abrasive grains that there occurs cohesion is present in burnishing surface, load will optionally put on the abrasive grains of cohesion.Therefore, easily on burnishing surface, cut is produced.When particularly weak to the base material or bonding interface with copper wiring advanced low-k materials carries out polishing, easily produce cut or interface peel (such as with reference to non-patent literature 1).In addition, in pouring foaming is shaping, because macromolecular elastomer easily foams unevenly, therefore, the polishing velocity when flatness of polished base material and polishing easily becomes uneven.And then be jammed in the closed pore of foam polymer precursor lentamente by abrasive grains or buffing, polishing velocity slowly reduces.

Following patent document 5 ~ 14 discloses a kind of polishing pad of non-woven fabric type, and the porous polyurethane that it makes wet type solidify is infiltrated in nonwoven fabric and obtains.Because the flexibility of non-woven fabric type polishing pad is excellent, therefore polishing pad is easily out of shape.Therefore, the abrasive grains be difficult to condensing in burnishing surface optionally applies load, therefore not easily produces cut.But because non-woven fabric type polishing pad is soft, therefore, polishing velocity is low.In addition, follow the surface configuration of polished base material due to non-woven fabric type polishing pad and be out of shape, therefore planarization performance is low, and described planarization performance is the characteristic making polished base material smooth.

In addition, following patent document 15 ~ 18 discloses a kind of polishing pad with high planarization performance of the nonwoven fabric containing superfine fibre.Such as patent document 15 discloses a kind of polishing pad formed by tablet, and it makes to be that to be infiltrated in average fineness be in the nonwoven fabric of polyester superfine fibre bundle obvolvent of 0.0001 ~ 0.01dtex for the macromolecular elastomer of principal component with polyurethane.The document discloses such polishing pad compared with existing polishing pad, achieve high-precision polishing.

In the polishing pad of the nonwoven fabric of common use superfine fibre, widely use and acupuncture perforation process and the nonwoven fabric that obtains have been carried out to the superfine fibre of staple fibre.Such nonwoven fabric is because apparent density is low and voidage is high, and therefore rigidity is low.Therefore, be out of shape owing to following the surface configuration of burnishing surface, therefore planarization performance is low.

Patent document 19 discloses a kind of polishing pad, it contains the fiber pseudoconjugant and macromolecular elastomer that are formed by superfine filamentary fibre bundle, a part for macromolecular elastomer is present in the inside of fibre bundle, superfine filament has carried out boundling, and the volume ratio of the part in removing space is the scope of 55 ~ 95%.

In addition, patent document 20 discloses a kind of polishing pad, and it is in the polishing pad with polishing layer and basalis, and between polishing layer and basalis, contain water absorption rate is the intermediate layer of less than 1%, and the difference of the D hardness of polishing layer and the D hardness in intermediate layer is less than 20.

Prior art document

Patent document

Patent document 1: Japanese Unexamined Patent Publication 2000-178374 publication

Patent document 2: Japanese Unexamined Patent Publication 2000-248034 publication

Patent document 3: Japanese Unexamined Patent Publication 2001-89548 publication

Patent document 4: Japanese Unexamined Patent Publication 11-322878 publication

Patent document 5: Japanese Unexamined Patent Publication 2002-9026 publication

Patent document 6: Japanese Unexamined Patent Publication 11-99479 publication

Patent document 7: Japanese Unexamined Patent Publication 2005-212055 publication

Patent document 8: Japanese Unexamined Patent Publication 3-234475 publication

Patent document 9: Japanese Unexamined Patent Publication 10-128674 publication

Patent document 10: Japanese Unexamined Patent Publication 2004-311731 publication

Patent document 11: Japanese Unexamined Patent Publication 10-225864 publication

Patent document 12: Japanese Unexamined Patent Application Publication 2005-518286 publication

Patent document 13: Japanese Unexamined Patent Publication 2003-201676 publication

Patent document 14: Japanese Unexamined Patent Publication 2005-334997 publication

Patent document 15: Japanese Unexamined Patent Publication 2007-54910 publication

Patent document 16: Japanese Unexamined Patent Publication 2003-170347 publication

Patent document 17: Japanese Unexamined Patent Publication 2004-130395 publication

Patent document 18: Japanese Unexamined Patent Publication 2002-172555 publication

Patent document 19: Japanese Unexamined Patent Publication 2008-207323 publication

Patent document 20: Japanese Unexamined Patent Publication 2011-200984 publication

Non-patent literature

Non-patent literature 1: " science (CMP サ イ エ Application ス) of CMP ", science forum of Co., Ltd. (Co., Ltd. サ イ エ Application ス Off ォ ー ラ system), on August 20th, 1997, p.113 ~ 119

Summary of the invention

The problem that invention will solve

The invention provides and a kind ofly there is high polishing velocity and the polishing pad of polishing velocity not easily rheological parameters' change with time.The method of dealing with problems

One aspect of the present invention relates to a kind of hard sheet, its nonwoven fabric comprising the superfine fibre with 0.0001 ~ 0.5dtex fiber number and the macromolecular elastomer be imparted in nonwoven fabric, the JIS-D hardness of this hard sheet is more than 45, equably 3 deciles are carried out to the cross section of thickness direction, and from any one face side, each layer after 3 deciles is set to the first top layer successively, when intermediate layer and the second top layer, measure the JIS-D hardness of any 3 totals 6 separately in the first top layer and intermediate layer, use the D hardness of total 6, the R% calculated by following formula is 0 ~ 20%,

R (%)=(D maximum hardness-D hardness minimum of a value)/D hardness mean value × 100,

Further, the total content of the ion making the pH of water change is 400 μ g/cm ³below.

In addition, another aspect of the present invention relates to a kind of polishing pad, and it possesses above-mentioned hard sheet as polishing layer.

In addition, another aspect of the present invention relates to a kind of manufacture method of hard sheet, and the method comprises following operation:

(1) operation of the long stapled fiber obvolvent sheet of superfine fibre generation fiber type is prepared, the long stapled fiber obvolvent sheet of described superfine fibre generation fiber type can form the nonwoven fabric of the superfine fibre with below 0.5dtex fiber number by superfine fibre process, and the apparent density of described nonwoven fabric is 0.35g/cm ³above;

(2) the first emulsion containing gelating agent and macromolecular elastomer is made to be impregnated in fiber obvolvent sheet, then the first emulsion gel is made, carry out heat drying again, make the operation that macromolecular elastomer solidifies thus, described gelating agent contains the ion that the pH of water is changed;

(3) by carrying out superfine fibre process to superfine fibre generation fiber type, the operation of the first complex containing nonwoven fabric and macromolecular elastomer is formed;

(4) the second emulsion containing gelating agent and macromolecular elastomer is made to be impregnated in the first complex, carry out heat drying again, macromolecular elastomer is made to solidify thus, thus form the operation of the second complex, described second complex is carried out 3 deciles equably at thickness direction, and from any one face side each layer after 3 deciles is set to successively the first top layer, intermediate layer and the second top layer time, the difference of the voidage in the first top layer and intermediate layer is less than 5%;

(5) the second complex is washed, make the total content of ion be 400 μ g/cm ³below, thus obtain the operation of hard sheet; And

(6) in order to make the case hardness of hard sheet be JIS-D hardness more than 45, at least one being selected from the first complex, the second complex and hard sheet is carried out the operation of hot pressing.

The effect of invention

The present invention can obtain for obtain there is high polishing velocity and polishing velocity not The book of Changes time the hard sheet of polishing pad that changes.

Accompanying drawing explanation

[Fig. 1] is the constructed profile of an embodiment of hard sheet.

Symbol description

1 nonwoven fabric

1a superfine fibre

1b fibre bundle

2 macromolecular elastomers

3 first top layers

4 intermediate layers

5 second top layers

Detailed description of the invention

Below, an embodiment of hard sheet of the present invention is described in detail.Fig. 1 is the constructed profile of the hard sheet 10 of present embodiment.In Fig. 1, the enlarged diagram of its part is shown in the lump in the region surrounded with circle.

As shown in Figure 1, hard sheet 10 comprises nonwoven fabric 1 and is imparted to the hard sheet of the macromolecular elastomer 2 in nonwoven fabric 1, and described nonwoven fabric 1 is the pseudoconjugant of superfine fibre 1a.For hard sheet 10, its JIS-D hardness is more than 45,3 deciles are carried out equably at thickness direction, and from face side by each layer after 3 deciles successively the first top layer 3, intermediate layer 4 and the second top layer 5 time, measure the JIS-D hardness of any 3 totals 6 separately in the first top layer 3 and intermediate layer 4, use the D hardness of total 6, the R% calculated by following formula is 0 ~ 20%

D hardness mean value × 100 of R (%)=(the D hardness minimum of a value in the D maximum hardness-6 in 6)/6.

In addition, preferably measure the JIS-D hardness of any 3 totals 6 separately in the second top layer 5 and intermediate layer 4, use the D hardness of total 6, the R% calculated by above formula is also 0 ~ 20%.And the total content of the ion making the pH of water change in this hard sheet is 400 μ g/cm ³below.

In hard sheet 10, the superfine fibre 1a forming nonwoven fabric 1 defines fibre bundle 1b, and described fibre bundle 1b is many superfine fibre 1a bunchys and obtains.In addition, multiple fibre bundle 1b is bondd by macromolecular elastomer 2 to each other.Preferred the more than half of multiple fibre bundle 1b are bondd by macromolecular elastomer 2.And then the superfine fibre 1a forming fibre bundle 1b is also bondd by macromolecular elastomer 2 to each other.The more than half of preferred superfine fibre 1a are bondd by macromolecular elastomer 2.Like this be that space is few, hardness is high and the hard sheet 10 of densification containing nonwoven fabric 1 and the nonwoven fabric of macromolecular elastomer 2 and the complex of macromolecular elastomer.The high fill-ratio (i.e. low voidage) of the stiffening effect that such hard sheet 10 causes due to fibre bundle 1b and hard sheet, therefore has high rigidity.

Hard sheet 10 is containing the nonwoven fabric 1 of superfine fibre being formed with fibre bundle.Be present in fibre bundle fibrillation or the fibrillation when polishing in the nonwoven fabric on surface.Its result, exposes the superfine fibre of high microsteping density at burnishing surface.The superfine fibre exposed, with wide area and polished substrate contact, in addition, can keep a large amount of slurries.And then, because the superfine fibre exposed makes the surperficial deliquescing of polishing pad, therefore, load is optionally applied to the condensation product of abrasive grains and is suppressed.Its result, can suppress the generation of cut.

In addition, the JIS-D hardness of hard sheet 10 is more than 45, at thickness direction, hardness is adjusted to even, make the JIS-D hardness of any 3 totals 6 separately in mensuration first top layer 3 and intermediate layer 2, and using the D hardness of total 6, the R% calculated by following formula is 0 ~ 20%

R (%)=(D maximum hardness-D hardness minimum of a value)/D hardness mean value × 100.

In addition, preferably at thickness direction, hardness is adjusted to even, make the JIS-D hardness of any 3 totals 6 separately in mensuration second top layer 5 and intermediate layer 2, and the R% using the D hardness of total 6 and calculate also is 0 ~ 20%.Like this, making hardness reach even by carrying out adjustment, the polishing of homogeneous can be carried out.

And the total content that hard sheet 10 is adjusted to the ion making the pH of water change is 400 μ g/cm ³below.In order to give macromolecular elastomer equably at thickness direction as above, in general, gelating agent can be used.Ion contained in hard sheet can make the pH of slurries change sometimes when polishing.When the pH of slurries there occurs change, easily make polishing velocity reduce, or easily make abrasive grains condense.Under these circumstances, by washing etc., ionic compound contained in hard sheet is reduced, the reduction of the polishing velocity produced because of the pH change of slurries can be suppressed thus.It should be noted that, the ion that the pH of water is changed refers to all ions pH being changed when being dissolved in water.

As described in detail below, the hard sheet of present embodiment by the thickness direction of the nonwoven fabric of the densification at superfine fibre evenly and give macromolecular elastomer with high containing ratio impregnation and manufacture.In addition, in the manufacture of such hard sheet, in order to macromolecular elastomer impregnation be given in nonwoven fabric with high containing ratio, preferably use the emulsion of the macromolecular elastomer containing gelating agent.And, in the manufacturing process of hard sheet, the ion total content that the pH of water is changed contained in gelating agent can be made to be 400 μ g/cm by carrying out washing ³below manufacture.

Below, each key element of the hard sheet of present embodiment is described in further detail.

Nonwoven fabric in present embodiment is formed by superfine fibre, and superfine fibre is preferably formed fibre bundle.

Superfine fibre has the fiber number of 0.0001 ~ 0.5dtex, preferably has the fiber number of 0.001 ~ 0.01dtex.When the fiber number of superfine fibre is lower than 0.0001dtex, when polishing, the superfine fibre of near surface is difficult to fibrillation fully, its result, and slurries maintenance dose reduces.When the fiber number of superfine fibre is more than 0.5dtex, because surface crosses thick, polishing velocity reduces, and abrasive grains easily condenses upon the surface of superfine fibre.

Superfine fibre is long fiber (long filament), and specifically, preferred average fiber length is more than 100mm, more preferably more than 200mm.The upper limit of average fiber length is not particularly limited, as long as be not cut off in obvolvent operation described later, such as also can comprise several meters, hundreds of rice, a few km or its above length fiber.The long fiber of superfine fibre improves by making fibre density the rigidity improving hard sheet.In addition, long fiber difficult drop-off when polishing.It should be noted that, the staple fibre of superfine fibre is difficult to improve fibre density, can not obtain the hard sheet that rigidity is high.In addition, staple fibre easily comes off when polishing.

Form the superfine fibre preferably many superfine fibre bunchys and form fibre bundle of nonwoven fabric.As the average cross-section of fibre bundle in cross section being present in thickness direction, especially from the viewpoint of obtaining the high hard sheet of rigidity, be preferably 80 μm ²above, more preferably 100 μm ²above, 120 μm are particularly preferably ²above.

In addition, for being present in the fibre bundle in thickness direction cross section, relative to total bundle number of the fibre bundle in the cross section of given thickness direction, preferably there are 40 μm ²the fibre bundle of above sectional area is more than 25%.Especially for when requiring the polishing pad of the silicon wafer purposes of high flatness, semiconductor wafer purposes, semiconductor equipment purposes, there are 40 μm ²the fibre bundle of above sectional area is preferably more than 40%, and more preferably more than 50%, be particularly preferably 100%.40 μm ²when the ratio of above fibre bundle is too low, there is the tendency of polishing velocity reduction or planarization performance step-down.

In addition, in the hard sheet of present embodiment, the Shu Midu of the fibre bundle of the unit are in the cross section of thickness direction is preferably 600 bundles/mm ²above, more preferably 1000 bundles/mm ²above, and be preferably 4000 bundles/mm ²below, more preferably 3000 bundles/mm ²below.When such Shu Midu, when polishing, the fibre bundle fibrillation on surface or fibrillation and form many superfine fibres, make the maintenance dose of slurries improve.In addition, by fibre bundle fibrillation or fibrillation, the surperficial deliquescing of burnishing surface and suppress the generation of cut.When Shu Midu is too low, there is the tendency that the fibre density step-down of the superfine fibre being formed in surface, polishing velocity reduction or planarization performance reduce.In addition, when the density of fibre bundle is too high, there is the maintenance dose of slurries or the tendency of polishing velocity reduction because surface is too fine and close.It should be noted that, in the hard sheet of present embodiment, from the viewpoint of raising polishing stable, preferably little at the density unevenness of thickness direction and direction, face fibre bundle.

Superfine fibre preferably by glass transition temperature (Tg) be more than 50 DEG C, further the preferred thermoplastic resin being more than 60 DEG C by glass transition temperature (Tg) formed.When the Tg of thermoplastic resin is too low, when polishing, rigidity is not enough, and planarization performance reduces, in addition, rigidity through time reduce and there is the tendency that polishing stable or polishing uniformity reduce.The upper limit of Tg is not particularly limited, but is preferably 300 DEG C, more preferably 150 DEG C on industry manufactures.It should be noted that, owing to becoming water suction state in polishing process, therefore, further preferred in the warm water of 50 DEG C after process, under moistening state, measure the Tg obtained be more than 50 DEG C.In addition, the water absorption rate of thermoplastic resin is preferably below 4 quality %, more preferably below 2 quality %.When water absorption rate is more than 4 quality %, when polishing, make because of the moisture absorbed lentamente in slurries rigidity through time reduce.Under these circumstances, planarization performance easily through time to reduce or polishing velocity or polishing uniformity easily change.Water absorption rate is preferably 0 ~ 2 quality %.

As the object lesson of thermoplastic resin, can enumerate such as: polyethylene terephthalate (PET, Tg is 77 DEG C, water absorption rate 1 quality %), (Tg is 67 ~ 77 DEG C to isophthalate modified polyethylene terephthalate, water absorption rate 1 quality %), (Tg is 67 ~ 77 DEG C to sulfoisophthalic acid modification polyethylene terephthalate, water absorption rate 1 ~ 4 quality %), (Tg is 85 DEG C to PBN, water absorption rate 1 quality %), (Tg is 124 DEG C to PEN, water absorption rate 1 quality %) etc. aromatic polyester-based resin, terephthalic acid (TPA) and the semiaromatic polyamide composition resinoid etc. such as nonanediol and methyl ethohexadiol copolymer nylon (Tg is 125 ~ 140 DEG C, water absorption rate 1 ~ 4 quality %).These materials can individually use, and also can combinationally use two or more.Wherein, from the viewpoint of can also maintaining rigidness, resistance to water and mar proof fully, preferred polyethylene terephthalate (PET), isophthalate modified polyethylene terephthalate, PBN, PEN.The particularly modified PET such as PET and isophthalate modified PET, become in the humid heat treatment operation of superfine fibre at the netted obvolvent sheet shaped by islands-in-sea bicomponent fibre described later and crispatura significantly, therefore, from the viewpoint of fine and close and highdensity fiber pseudoconjugant can be formed, easily to improve the rigidity of hard sheet and not easily produce the rheological parameters' change with time etc. that moisture causes when polishing be preferred.

In addition, in the scope not damaging effect of the present invention, as required can containing the superfine fibre formed by other thermoplastic resin.As such thermoplastic resin, the aromatic polyesters such as PLA, polybutylene terephthalate (PBT), Polyethylene terephthalate, polydiethylene glycol succinate, polybutylene succinate, poly-butanedioic acid tetramethylene adipate, poly butyric ester-poly-hydroxyl pentanoate copolymer or aliphatic polyester and copolymer thereof can be combinationally used; Amorphous nylon and the copolymers thereof such as nylon 6, nylon66 fiber, nylon 10, nylon 11, nylon 12; The TPO such as polyethylene, polypropylene; Modified polyvinylalcohol containing 25 ~ 70 % by mole of ethylene unit; The elastomers etc. such as polyurethane elastomer, nylon-type elastomer, polyester elastomer.

Hard sheet comprises the macromolecular elastomer be imparted in the nonwoven fabric of superfine fibre.

As the object lesson of macromolecular elastomer, can enumerate such as: polyurethane, polyamide-based elastomer, (methyl) acrylic ester elastomer, (methyl) Acrylate-styrene bipolymer class elastomer, (methyl) acrylic ester-acrylonitrile class elastomer, (methyl) acrylate-olefin class elastomer, (methyl) acrylate-(hydrogenation) isoprenoid elastomer, (methyl) acrylate-butadiene class elastomer, styrene-butadiene class elastomer, styrene-hydrogenated isoprene class elastomer, acrylonitrile-butadiene class elastomer, acrylonitrile-butadiene-styrene (ABS) class elastomer, vinyl acetate class elastomer, (methyl) acrylic ester-vinylphenyl acetate class elastomer, ethane-acetic acid ethyenyl ester class elastomer, ethylene-olefin class elastomer, polysiloxane-based elastomer, fluoroelastomer, and polyester elastomer etc.

Macromolecular elastomer is preferably non-porous state.It should be noted that, non-porous state refers to the such space (closed pore) not having in fact cellular or spongy macromolecular elastomer and have.Such as, the macromolecular elastomer with many closed pores not obtaining as made solvent based polyurethane solidify is referred to.

When macromolecular elastomer is non-porous state, can obtain high polishing stable, not easy to wear, in addition, slurries residue or polishing pad chip not easily remain in space.Therefore, high polishing velocity can be kept for a long time.In addition, because the cementability for superfine fibre is high, therefore, coming off of fiber is not easily caused.In addition, owing to can obtain high rigidity, therefore planarization performance is excellent.

The water absorption rate of macromolecular elastomer is preferably 0.5 ~ 8 quality %, more preferably 1 ~ 6 quality %.When the water absorption rate of macromolecular elastomer is too low, the wettability for slurries reduces., there is the tendency that polishing velocity, polishing uniformity, polishing stable reduction or abrasive grains easily condense in its result.When the water absorption rate of macromolecular elastomer is too high, when polishing hard sheet rigidity through time reduce, planarization performance reduce.In addition, polishing velocity or the easy change of polishing uniformity.It should be noted that, the water absorption rate of macromolecular elastomer refer to the film immersion of the macromolecular elastomer after by drying process make in the water of room temperature its saturated swelling time water absorption rate.It should be noted that, when containing two or more macromolecular elastomer, the form of the value sum that the water absorption rate being multiplied by each macromolecular elastomer with mass fraction obtains carries out theory calculate.

The water absorption rate of macromolecular elastomer can adjust by importing hydrophilic functional group or adjusting the degree of cross linking.As hydrophilic functional group, can enumerate such as: the poly alkylene glycol base etc. of carboxyl, sulfonic group and carbon number less than 3.Hydrophilic radical can by carrying out copolymerization by the monomer with hydrophilic radical and importing.As the copolymerization ratios of monomeric unit with hydrophilic radical, be preferably 0.1 ~ 20 quality %, more preferably 0.5 ~ 10 quality %.

The storage modulus of macromolecular elastomer at 150 DEG C [E ' (150 DEG C, dry (dry))] be preferably 0.1 ~ 100MPa, more preferably 1 ~ 80MPa.The storage modulus of macromolecular elastomer can be adjusted by the adjustment degree of cross linking.It should be noted that, when containing two or more macromolecular elastomer, the form of the value sum that [E ' (150 DEG C, dry (dry))] that be multiplied by each macromolecular elastomer with mass fraction obtains carries out theory calculate.

Macromolecular elastomer may be used singly or in combination of two or more.Wherein, from the viewpoint of excellent to the caking property of superfine fibre, optimization polyurethane.

Be preferably formed the superfine fibre of fibre bundle by macromolecular elastomer boundling, preferably the radical more than half of superfine fibre passes through macromolecular elastomer boundling further.

In addition, preferred multiple fibre bundle is to each other by being present in the macromolecular elastomer bonding outside fibre bundle, and the bundle more than half of further optimum fiber bundle is bondd by macromolecular elastomer and exists with bulk.Bondd to each other by fibre bundle and improve the morphological stability of hard sheet, thus improving polishing stable.By with macromolecular elastomer by superfine fibre boundling or make fibre bundle be bonded to one another, the hard sheet that hardness is even and high can be obtained.

When boundling does not occur the superfine fibre forming fibre bundle, because superfine fibre is with flexibility, be therefore difficult to obtain high planarization performance.In addition, in polishing, superfine fibre easily comes off, and abrasive grains condenses on the fiber come off and easily produces cut.Superfine fibre is referred to by macromolecular elastomer boundling: the macromolecular elastomer that the superfine fibre being present in fibre bundle inside is present in fibre bundle inside is bonding and in bond.

The ratio (nonwoven fabric/macromolecular elastomer) of the nonwoven fabric in hard sheet and macromolecular elastomer is preferably 90/10 ~ 55/45 by quality ratio, and more preferably 85/15 ~ 65/35.When the ratio of nonwoven fabric and macromolecular elastomer is above-mentioned scope, easily improve the rigidity of hard sheet.In addition, the density of the superfine fibre being exposed to hard sheet surface can be improved fully.Its result, can improve polishing stable, polishing velocity and planarization performance fully.

From the viewpoint of keeping high rigidity, the apparent density of hard sheet is preferably 0.5 ~ 1.2g/cm ³, more preferably 0.6 ~ 1.2g/cm ³.

The JIS-D hardness of the hard sheet of present embodiment is more than 45,3 deciles are carried out equably in the cross section of thickness direction, and from any one face side each layer after 3 deciles is set to successively the first top layer, intermediate layer and the second top layer time, measure the JIS-D hardness of any 3 totals 6 separately in the first top layer and intermediate layer, use the D hardness of total 6, the R% calculated by following formula is 0 ~ 20%

Mean value × 100 of the D hardness of R (%)=(D maximum hardness-D hardness minimum of a value)/6.

In addition, preferably measure the JIS-D hardness of any 3 totals 6 separately in the second top layer and intermediate layer, use the D hardness of total 6, the R% calculated by above formula is also 0 ~ 20%.

The JIS-D hardness of hard sheet is more than 45, is preferably 45 ~ 75, more preferably 50 ~ 70.Counting more than 45 by the hardness on the first top layer being adjusted to JIS-D hardness, high planarization performance can be obtained.When JIS-D much higher hard, easily produce cut.It should be noted that, owing to making the superfine fibre of high microsteping density be exposed to surface, therefore, although the hard sheet of present embodiment is hard, surface is soft.Therefore, not easily cut is produced.

Measure the JIS-D hardness of any 3 totals 6 separately in the first top layer and intermediate layer, use the D hardness of total 6, the R% calculated by above-mentioned formula is 0 ~ 20%, is preferably 0 ~ 15%.When the R% in the first top layer and intermediate layer is above-mentioned scope, when being used as polishing pad, the change of the polishing velocity in the first top layer and intermediate layer diminishes, and can obtain stable polishing performance.When R% is more than 20%, in polishing, the change of polishing velocity increases, and can not obtain stable polishing performance.It should be noted that, the arbitrary point measuring JIS-D hardness refers to: which the some mensuration in its layer is arbitrary, and no matter at which point measure, R% is 0 ~ 20%.Under these circumstances, owing to not only hardness also can not be made uneven at thickness direction but also at width, therefore, polishing velocity is also even in the in-plane direction, thus, can obtain stable polishing performance.Similarly, to measure in the second top layer and intermediate layer separately any 3 amount to the JIS-D hardness of 6, use the D hardness of total 6, the R% calculated by above-mentioned formula is 0 ~ 20%, more preferably 0 ~ 15%.

For the hard sheet of present embodiment, the total content of the ion that the pH of water is changed is 400 μ g/cm ³below.As described later, the hard sheet of present embodiment manufactures as follows: such as make the emulsion of macromolecular elastomer be impregnated in nonwoven fabric, then macromolecular elastomer carried out heat drying and make it solidify, being imparted in nonwoven fabric by macromolecular elastomer thus.In such operation, carry out drying containing the moisture in the emulsion be immersed in nonwoven fabric from surface.Therefore, with the carrying out of moisture evaporation, to cause in nonwoven fabric emulsion to the migration of top layer movement.When causing migration, macromolecular elastomer is mainly present near the top layer of nonwoven fabric unevenly, and the macromolecular elastomer near intermediate layer tails off, and space easily residues near intermediate layer.Gelating agent is matched with in emulsion by migrating across like this, and makes emulsion gel before it is dried and suppressed.The discoveries such as the present inventor: when the ion that the pH of water is changed contained in the gelating agent obtained is more than specified rate to residue in hard sheet, polishing velocity can be made to reduce when polishing.

The total content of the ion that the pH of water is changed contained in hard sheet is 400 μ g/cm ³below, 350 μ g/cm are preferably ³, more preferably 100 μ g/cm ³below.In addition, the total content of ion is preferably 0 μ g/cm ³, from the viewpoint of industrial washing efficiency, be preferably 1 ~ 100 μ g/cm ³, more preferably 10 ~ 50 μ g/cm ³left and right.The total content of the ion that the pH of water is changed contained in hard sheet is more than 400 μ g/cm ³when, slurries cause pH to change, and polishing velocity reduces, and easily makes abrasive grains condense further.

It should be noted that, the ion that the pH of water is changed is all ions making pH change when being dissolved in water, specifically, sulfate ion contained in such as common gelating agent can be enumerated, nitrate ion, carbanion, ammonium ion, sodium ion, calcium ion, potassium ion etc.

[manufacture method of polishing pad]

Below, an example of the manufacture method of hard sheet is described in detail.Hard sheet such as can manufacture through following operation.

(1) operation of the long stapled fiber obvolvent sheet of superfine fibre generation fiber type is prepared

In this operation, prepare the long stapled fiber obvolvent sheet of superfine fibre generation fiber type.The long stapled fiber obvolvent sheet of superfine fibre generation fiber type such as can manufacture as follows.

First, manufacture the long fibre net formed by islands-in-sea bicomponent fibre, described islands-in-sea bicomponent fibre is using water insoluble thermoplastic resin as sea component, using water-insoluble thermoplastic resin as island component.Islands-in-sea bicomponent fibre is the superfine fibre generation fiber type producing the superfine fibre formed by the resin of island component by dissolving sea component.It should be noted that, in the present embodiment, the example using islands-in-sea bicomponent fibre as superfine fibre generation fiber type is described, but the known superfine fibre generation fiber types such as multi-laminate stratotype cross-section fibers also can be used to replace islands-in-sea bicomponent fibre.

As water insoluble thermoplastic resin, be to dissolve removing by water, alkaline aqueous solution, acidic aqueous solution etc. or to decompose the thermoplastic resin of removing, using can the resin of melt spinning.As the object lesson of water insoluble thermoplastic resin, can enumerate such as: the PVA resinoids such as polyvinyl alcohol (PVA), PVA copolymer; Containing polyethylene glycol and/or the sulfonic acid alkali metal salts modified poly ester as copolymer composition; Poly(ethylene oxide) etc.Wherein, preferably PVA resinoid is used.

By when making PVA resinoid dissolve containing PVA resinoid as the islands-in-sea bicomponent fibre of sea component, the superfine fibre as island component is significantly crispaturaed.Its result, can obtain the nonwoven fabric that fibre density is high.In addition, by when making PVA resinoid dissolve containing the resinoid islands-in-sea bicomponent fibre of PVA, can not decompose or dissolve as the superfine fibre of island component or macromolecular elastomer, therefore, not easily cause the physical property of superfine fibre or macromolecular elastomer to reduce.

As PVA resinoid, from the viewpoint of the physical property improving islands-in-sea bicomponent fibre, preferably use containing 4 ~ 15 % by mole of ethylene unit, the further ethylene modified PVA preferably containing 6 ~ 13 % by mole of ethylene unit.

The resinoid viscometric degree of polymerization of PVA is preferably 200 ~ 500, and more preferably 230 ~ 470, be particularly preferably the scope of 250 ~ 450.In addition, as the resinoid fusing point of PVA, consider from mechanical property and excellent heat stability aspect and the excellent aspect of melt spinning, be preferably 160 ~ 250 DEG C, more preferably 175 ~ 224 DEG C, be particularly preferably the scope of 180 ~ 220 DEG C.

As forming the water-insoluble thermoplastic resin of island component, be to be dissolved removing by water, alkaline aqueous solution, acidic aqueous solution etc. or to decompose the thermoplastic resin of removing, can use can the resin of melt spinning.As the object lesson of water-insoluble thermoplastic resin, the various resins of above-mentioned formation superfine fibre, preferably Tg can be used to be more than 50 DEG C and water absorption rate is the thermoplastic resin of below 4 quality %.

In addition, water-insoluble thermoplastic resin such as can contain the additives such as catalyst, painted preventing agent, heat-resistant agent, fire retardant, lubricant, anti-fouling agent, fluorescent whitening agent, delustering agent, colouring agent, gloss improvers, antistatic additive, aromatic, deodorant, antiseptic, mite-proof agent, inorganic particles.

Islands-in-sea bicomponent fibre can use composite spinning method to manufacture, described composite spinning method be water insoluble thermoplastic resin, the water-insoluble thermoplastic resin low with the compatibility of water insoluble thermoplastic resin are carried out melt spinning respectively after, make its Composite.And islands-in-sea bicomponent fibre preferably forms net with long stapled state.

The long stapled net of islands-in-sea bicomponent fibre can obtain as follows: by such as spun-bond process by water insoluble thermoplastic resin and water-insoluble thermoplastic resin melt spinning, then carry out Composite, after stretching further, makes it pile up.It should be noted that, long fiber is the continuous print fiber manufactured without cut-out operation during manufacture staple fibre.Below, an example of the manufacture method of the long stapled net of islands-in-sea bicomponent fibre is described in detail.

First, utilize respective extruder to carry out melting mixing respectively water insoluble thermoplastic resin and water-insoluble thermoplastic resin, from different spinning-nozzles, the tow of molten resin is sprayed respectively simultaneously.And, after making the tow composite nozzle compound be ejected, make it spray from the nozzle bore of spinneret, form islands-in-sea bicomponent fibre thus.

Water insoluble thermoplastic resin in islands-in-sea bicomponent fibre and the mass ratio of water-insoluble thermoplastic resin are not particularly limited, and are preferably 5/95 ~ 50/50, more preferably 10/90 ~ 40/60.When the mass ratio of water insoluble thermoplastic resin and water-insoluble thermoplastic resin is above-mentioned scope, from the viewpoint of can obtain highdensity nonwoven fabric, superfine fibre formative also excellent be preferred.In addition, in melt composite spinning, the island number in islands-in-sea bicomponent fibre is preferably 4 ~ 4000 islands/fiber, more preferably 10 ~ 1000 islands/fiber.In addition, the fiber number of islands-in-sea bicomponent fibre is not particularly limited, but considers from payable viewpoint, is preferably about 0.5 ~ 3dtex.

Islands-in-sea bicomponent fibre, after being cooled by cooling device, is used the aspirator such as jet nozzle to stretch with the high velocity air of the speed being equivalent to hauling speed 1000 ~ 6000m/ and dividing, makes it reach target fiber number.Then, long stapled net is formed by being piled up in portable collection face by the composite fibre after stretching.Now, can as required by piled up long fibre net part pressure viscosity.

Then, make net overlapping multiple and make its obvolvent.The obvolvent process of net can utilize needle point method or High-Pressure Water process etc. to carry out.As representative examples, to utilizing the obvolvent process of needle point method to be described in detail.

First, the polysiloxane-based finishes such as the finish of the finish preventing pin from bending, antistatic finish, raising obvolvent or mineral oils finish are imparted in net.Then, net obvolvent is made by needle point method.Excellent from the viewpoint of operability, the net weight per unit area after obvolvent is preferably 100 ~ 1500g/m ²scope.

Secondly, by making, the long stapled net of obvolvent shrinks and improves fibre density.Compared with the situation making the net of staple fibre shrink, by making long stapled net shrink, can significantly shrink.Shrink process preferably carries out the damp and hot shrink process such as Steam Heating.As Steam Heating condition, can enumerate that such as ambient temperature is in the scope of 60 ~ 130 DEG C, relative humidity more than 75%, further preferably relative humidity more than 90%, the heat treated condition of 60 ~ 600 seconds.

Damp and hot shrink process preferably with percentage reduction of area be more than 35%, more preferably more than 40% mode the long stapled net of institute's obvolvent is shunk.Like this, by making it shrink with high shrinkage, fibre density becomes high.From the viewpoint of the limit of shrinking and treatment effeciency, the upper limit of percentage reduction of area is preferably about less than 80%.It should be noted that, percentage reduction of area (%) utilizes following formula to calculate.

Area × 100 of the obvolvent net before (area of the obvolvent net after the area-shrink process of the obvolvent net before shrink process)/shrink process

The obvolvent net having carried out damp and hot shrink process in this wise can improve fibre density further further by warm-up mill or hot pressing.As the change of the obvolvent net weight per unit area before and after damp and hot shrink process, compared with the weight per unit area before shrink process, weight per unit area after shrink process is preferably more than 1.2 times (mass ratioes), more preferably more than 1.5 times and less than 4 times, more preferably less than 3 times.So, the long stapled net (hereinafter referred to as fiber obvolvent sheet) of islands-in-sea bicomponent fibre can be obtained.

It is 0.35 ~ 0.90g/cm that such fiber obvolvent sheet is converted to apparent density by the superfine fibre of islands-in-sea bicomponent fibre below ³nonwoven fabric.

Containing long stapled obvolvent net compared with the obvolvent net containing staple fibre, the damp and hot contraction significantly by superfine fibre.Therefore, the fibre density of superfine fibre becomes finer and close.And, by optionally removing the water insoluble thermoplastic resin of islands-in-sea bicomponent fibre, the nonwoven fabric of the fibre bundle containing superfine fibre can be formed.Now, dissolved at water insoluble thermoplastic resin the part extracted and formed space.By giving macromolecular elastomer with high containing ratio in this space, will form the superfine fibre boundling of fibre bundle, fibre bundle is bonded to one another simultaneously.So, the hard sheet that fibre density is high, voidage is low, rigidity is high can be obtained.

(2) the first emulsion containing gelating agent (this gelating agent contains the ion making the pH of water change) and macromolecular elastomer is made to be impregnated in fiber obvolvent sheet, then the first emulsion gel is made, carry out heat drying again, make the operation that macromolecular elastomer solidifies thus

In this operation, macromolecular elastomer is filled in fiber obvolvent sheet equably at thickness direction.Emulsion due to macromolecular elastomer is high concentration, low viscosity and impregnation impregnability is also excellent, therefore, easily highly in fiber obvolvent sheet to fill.In addition, by making to contain gelating agent in the emulsion of macromolecular elastomer, emulsion can be suppressed when drying in the migration that thickness direction is uneven.

Different from the situation of the solution using current normally used macromolecular elastomer, when using the emulsion of macromolecular elastomer, the macromolecular elastomer of non-porous state can be formed.

As macromolecular elastomer, from the viewpoint of the cementability height to fiber, the macromolecular elastomer of preferred hydrogen bond.The macromolecular elastomer of hydrogen bond is the elastomer formed by the macromolecule by hydrogen bond crystallization or cohesion such as polyurethane, polyamide-based elastomer, polyvinyl alcohol elastomer etc.

Below, the situation using polyurethane as macromolecular elastomer is described as representative examples in detail.

As polyurethane, the various polyurethane by making the macromolecule polyol of mean molecule quantity 200 ~ 6000, organic multiple isocyanate and chain extender obtain with given molar ratio reaction can be enumerated.

As the object lesson of macromolecule polyol, can enumerate such as: polyether alcohol and the copolymer thereof such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, poly-(methyltetramethylene glycol); Polybutylene glyool adipate, polydiethylene glycol sebacate glycol, polyhexamethylene adipate glycol, poly-(adipic acid 3-methyl isophthalic acid, 5-pentadiol ester) glycol, poly-(decanedioic acid 3-methyl isophthalic acid, the 5-pentadiol ester) polyester polyol such as glycol, polycaprolactone glycol and copolymer thereof; Polycarbonate-based polyalcohol and the copolymers thereof such as polyhexamethylene carbonate diol, poly-(3-methyl isophthalic acid, 5-pentylidene carbonic acid ester) glycol, poly-5-methylene carbonate glycol, polytetramethylene carbonate diol; Polyestercarbonate polyalcohol etc.In addition, 3 functional alcohol, the pentaerythrites etc. such as trimethylolpropane 4 short chain alcohol such as polyfunctional alcohol or ethylene glycol, propylene glycol, BDO, 1,6-hexylene glycol such as functional alcohol can also be combinationally used as required.These materials may be used singly or in combination of two or more.Particularly from the viewpoint of the hard sheet that can obtain the excellent in te pins of durability such as hydrolytic resistance, oxidative resistance, preferably use the mixture of non-crystalline polycarbonate-based polyalcohol, the polycarbonate-based polyalcohol of ester ring type, the polycarbonate-based polyalcohol of straight-chain and above-mentioned polycarbonate-based polyalcohol and polyether alcohol or polyester polyol.In addition, from the viewpoint of good especially to the wettability of water, the polyurethane of the poly alkylene glycol base preferably containing carbon number less than 5, particularly carbon number less than 3.

As the object lesson of organic multiple isocyanate, can enumerate such as: aliphatic or the alicyclic diisocyanates etc. such as hexamethylene diisocyanate, isophorone diisocyanate, ENB vulcabond, HMDI are without xanthochromia type vulcabond; 2,4-toluene di-isocyanate(TDI), 2,6-toluene di-isocyanate(TDI)s, 4, the aromatic diisocyanates etc. such as 4 '-methyl diphenylene diisocyanate, xylylene diisocyanate polyurethane.In addition, the polyfunctional isocyanate such as 3 functional isocyanate, 4 functional isocyanate can also be combinationally used as required.These materials may be used singly or in combination of two or more.Wherein, from the viewpoint of high to the cementability of fiber and the high hard sheet of hardness can be obtained, preferably 4,4 '-dicyclohexyl methyl hydride diisocyanate, 2,4-toluene di-isocyanate(TDI), 2,6-toluene di-isocyanate(TDI), 4,4 '-methyl diphenylene diisocyanate, xylylene diisocyanate.

As the object lesson of chain extender, can enumerate such as: the Diamines such as hydrazine, ethylenediamine, propane diamine, hexamethylene diamine, nine methylene diamine, xylylene diamine, isophorone diamine, piperazine and derivative, adipic dihydrazide, isophthalic dihydrazide; Diethylenetriamine etc. three amine; The tetraamines such as triethylene tetramine; Ethylene glycol, propylene glycol, BDO, 1,6-hexylene glycol, Isosorbide-5-Nitrae-glycols such as bis-(beta-hydroxy ethyoxyl) benzene, Isosorbide-5-Nitrae-cyclohexanediol etc.; Trimethylolpropane etc. three alcohols; Pentaerythrite etc. four alcohols; The alkamine such as ethylaminoethanol, aminopropanol etc.These materials may be used singly or in combination of two or more.Wherein, from the viewpoint of completing curing reaction at short notice, preferred compositions uses two or more in the triamine such as hydrazine, piperazine, hexamethylene diamine, isophorone diamine and derivative thereof, ethene triamine.In addition, when chain extending reaction, chain extender and following substances can be combinationally used, described material is: the monoamines such as ethamine, propylamine, butylamine; The carboxylic monoamine compound such as 4-Aminobutanoicacid, 6-aminocaprolc acid; The single methanol classes such as methyl alcohol, ethanol, propyl alcohol, butanols.

In addition, by combinationally using 2, two (hydroxymethyl) propionic acid, 2 of 2-, two (hydroxymethyl) butyric acid, 2 of 2-, carboxyl isoiony group imports in the skeleton of polyurethane by the carboxylic glycol etc. such as two (hydroxymethyl) valeric acids of 2-, can make to improve further the wettability of water.

In addition, in order to control water absorption rate, the storage modulus of polyurethane, form cross-linked structure preferably by the crosslinking agent of the functional group added containing more than 2 functional group reactionses that can have with the monomeric unit for the formation of polyurethane in molecule or the self-crosslinking compound such as polyisocyanates compounds, multifunctional blocked isocyanate compounds.

As the combination of the functional group of monomeric unit and the functional group of crosslinking agent, can enumerate: carboxyl and azoles quinoline base, carboxyl and carbodiimide-based, carboxyl and epoxy radicals, carboxyl and cyclocarbonate radical, carboxyl and '-aziridino, carbonyl and hydrazine derivate, hydrazide derivatives etc.Wherein, from the viewpoint of the rigidity or the excellent in wear resistance that easily form crosslinked, hard sheet, the monomeric unit particularly preferably with carboxyl with have the combination of the crosslinking agent of azoles quinoline base, carbodiimide-based or epoxy radicals, have hydroxyl or amino monomeric unit and have blocked isocyanate base crosslinking agent combination and there is the monomeric unit of carbonyl and the combination of hydrazine derivate or hydrazide derivatives.It should be noted that, from the viewpoint of the emulsion intercalation method that can keep macromolecular elastomer, in the heat treatment step preferably after being imparted to by polyurethane in fiber obvolvent sheet, form cross-linked structure.Wherein, particularly preferably the useful life of cross-linking properties and emulsion excellent and at the also no problem carbodiimide-based of secure context and/or azoles quinoline base.As the crosslinking agent with carbodiimide-based, the aqueous dispersion carbodiimides such as " CARBODILITE E-01 ", " CARBODILITE E-02 ", " CARBODILITE V-02 " that such as Misshin Spinning Co., Ltd manufactures can be enumerated.In addition, as having the crosslinking agent of azoles quinoline base, can enumerate the aqueous dispersion such as " Epocros K-2010E ", " Epocros K-2020E ", " EpocrosWS-500 " that such as Nippon Shokubai Co., Ltd manufactures oxazoline compound.As the use level of crosslinking agent, relative to polyurethane, the active ingredient of crosslinking agent is preferably 1 ~ 20 quality %, is more preferably 1.5 ~ 1 quality %, more preferably 2 ~ 10 quality %.

In addition, from the viewpoint of improving the cementability of superfine fibre thus the rigidity of raising fibre bundle, as the containing ratio of the composition of macromolecule polyol in polyurethane, below 65 quality %, more preferably below 60 quality % are preferably.In addition, from the viewpoint of the generation that can be suppressed cut by the elasticity of giving appropriateness, more than 40 quality %, more preferably more than 45 quality % are preferably.

The method preparing the emulsion of polyurethane is not particularly limited, and can use known method.Specifically, can enumerate such as by using the monomer with hydrophilic radicals such as carboxyl, sulfonic group, hydroxyls give the self emulsifiable method of water as copolymer composition to polyurethane or add surfactant and make the method for its emulsification in polyurethane.Due to excellent to the wettability of water as the macromolecular elastomer of copolymer composition containing the monomeric unit with hydrophilic radical, therefore, a large amount of slurries can be kept.

As the object lesson of surfactant that can be used for emulsification, can enumerate such as: the anionic surfactant such as lauryl sodium sulfate, ammonium lauryl sulfate, polyoxyethylene tridecyl ether sodium acetate, neopelex, alkyl diphenyl base ether sodium disulfonate, dioctyl sodium sulphosuccinate; The nonionic surface active agent etc. such as ethylene nonyl phenyl ether, NONIN HS 240, polyoxyethylene lauryl ether, polyoxyethylene stearyl base ether, polyox-yethylene-polyoxypropylene block copolymer.In addition, can use there is reactive so-called reactive surfactant.In addition, by the cloud point of suitable option table surface-active agent, heat-sensitive gel can be given to emulsion.

As the solid component concentration of emulsion, from the viewpoint of being filled in fiber obvolvent sheet thickness direction is high equably by macromolecular elastomer, be preferably 15 ~ 40 quality %, more preferably 25 ~ 35 quality %.In addition, as the particle diameter of emulsion, be preferably 0.01 ~ 1 μm, more preferably 0.03 ~ 0.5 μm.

First emulsion comprises the gelating agent containing the ion making the pH of water change.Gelating agent by make emulsion pH change and for making emulsion particle gelation by heating.Drying is carried out from surface containing the moisture in the emulsion be immersed in nonwoven fabric.Therefore, with the carrying out of the evaporation of moisture, easily cause the emulsion in nonwoven fabric to the migration of top layer movement.Emulsion in nonwoven fabric there occurs migration, macromolecular elastomer is present near the top layer of nonwoven fabric unevenly in a large number, and the macromolecular elastomer near intermediate layer tails off, easy residual clearance near intermediate layer.When voids left is near intermediate layer, the hardness in intermediate layer reduces, and in addition, hardness becomes uneven.Such migration is by be matched with gelating agent in emulsion and to make emulsion gel before it is dried and be suppressed.

As gelating agent, as long as make the pH of emulsion change and reach the water miscible salt making the degree of emulsion particle gelation by heating, just can use with being not particularly limited.As its object lesson, the such as sodium sulphate, ammonium sulfate, sodium carbonate, calcium chloride, calcium sulfate, calcium nitrate, zinc oxide, zinc chloride, magnesium chloride, potassium chloride, potash, sodium nitrate, plumbi nitras etc. of the inorganic salts as monovalence or divalence can be enumerated.

As the gelating agent in the first emulsion containing proportional, from the viewpoint of moderately gelation can be given, be preferably 0.5 ~ 5 parts by mass relative to macromolecular elastomer 100 parts by mass, more preferably 0.6 ~ 4 parts by mass.

First emulsion can contain water-soluble high-molecular compound, dyestuff, pigment, the inorganic particles etc. such as penetrant, defoamer, lubricant, waterproofing agent, oil-proofing agent, tackifier, extender, curing accelerator, antioxidant, ultra-violet absorber, fluorescer, mould inhibitor, blowing agent, polyvinyl alcohol and carboxymethyl cellulose further.

The method that first emulsion is impregnated in fiber obvolvent sheet is not particularly limited, such as, can use the methods such as the painting of dip/squeeze (nip), cutter, rod painting or roller coat.

And, make after the first emulsion is impregnated in fiber obvolvent sheet, to heat, thus, the gelation in fiber obvolvent sheet of the first emulsion.As the heating condition for such gelation, preferably use such as at 40 ~ 90 DEG C, the further preferred condition keeping about 0.5 ~ 5 minute at 50 ~ 80 DEG C.In addition, from the viewpoint of suppressing the migration of sharply to evaporate the emulsion caused because of moisture from top layer also can heat internal layer equably, steam is preferably utilized to heat.

And, after making the first emulsion gel, carry out heat drying, make macromolecular elastomer solidify thus.

As heat drying, the method for carrying out heat drying in the drying devices such as air drier or the method etc. of carrying out heat drying after infrared heating in drying machine can be set forth in.As the condition of heat drying, can enumerate such as with maximum temperature be 130 ~ 160 DEG C, preferably maximum temperature is the condition that the mode of 135 ~ 150 DEG C heats 2 ~ 10 minutes further.By heat drying, the moisture in the first emulsion evaporated and macromolecular elastomer is condensed equably, macromolecular elastomer also can be imparted in fiber obvolvent sheet equably at thickness direction thus.

(3) by carrying out superfine fibre process to superfine fibre generation fiber type, the operation of the first complex containing nonwoven fabric and macromolecular elastomer is formed

There is islands-in-sea bicomponent fibre contained in the fiber obvolvent sheet of macromolecular elastomer to carry out superfine fibre process by impregnation being given, being formed containing the nonwoven fabric of superfine fibre and the first complex of macromolecular elastomer.

This operation is by forming the operation of superfine fibre from containing the superfine fibre process removing water insoluble thermoplastic resin in the islands-in-sea bicomponent fibre of the water insoluble thermoplastic resin as island component and the water-insoluble thermoplastic resin as sea component.

Superfine fibre process will form the water insoluble thermoplastic resin dissolves removing of sea component by the fiber obvolvent sheet containing islands-in-sea bicomponent fibre being carried out in water, alkaline aqueous solution, acidic aqueous solution etc. hot water heating process or decompose the process of removing.

As the object lesson of hot water heating process, preferred use is following method such as: be impregnated in by fiber obvolvent sheet and as the first stage, in the hot water of 85 ~ 100 DEG C, then processed for 100 ~ 600 seconds further as second stage 5 ~ 300 seconds in the hot water of 65 ~ 90 DEG C.In addition, in order to improve dissolved efficiency, can carry out utilizing the extrusion process of roller, High-Pressure Water process, ultrasonic wave process as required, rinse process, stir process, rubbing process etc.

By carrying out hot water heating process to fiber obvolvent sheet, water insoluble thermoplastic resin dissolves and forms superfine fibre from islands-in-sea bicomponent fibre.It should be noted that, when forming superfine fibre, superfine fibre is significantly crispaturaed.Because this is crispaturaed, the fibre density of superfine fibre becomes fine and close.In addition, by removing water insoluble thermoplastic resin from islands-in-sea bicomponent fibre, the part existing for water insoluble thermoplastic resin forms space.Thereafter, in operation, macromolecular elastomer is filled in this space.In addition, by carrying out hot water heating process to fiber obvolvent sheet, gelating agent contained in fiber obvolvent sheet is also dissolved in hot water and is removed.Form the first complex thus.

(4) make the second emulsion containing gelating agent and macromolecular elastomer be impregnated in the first complex, then make the second emulsion gel, then carry out heat drying, make macromolecular elastomer solidify thus, thus form the operation of the second complex

As mentioned above, in the first complex formed by removing water insoluble thermoplastic resin from islands-in-sea bicomponent fibre, the part existing for water insoluble thermoplastic resin forms space.In order to obtain the homogeneous of present embodiment and have the hard sheet of high rigidity, macromolecular elastomer is utilized to fill space in the first complex to fetter superfine fibre.

In the space formed by macromolecular elastomer being filled in removing water insoluble thermoplastic resin, can the voidage of hard sheet be reduced superfine fibre boundling.When superfine fibre forms fibre bundle, easily utilize capillarity impregnation emulsion.

As the second emulsion, the emulsion same with the first emulsion can be used.It should be noted that, the second emulsion and the first emulsion can be identical composition, also can be different compositions.

In this operation, preferred imparting second emulsion also makes its gelation, make the second formed complex at thickness direction 3 deciles equably, and from any one face side each layer after 3 deciles is set to successively the first top layer, intermediate layer and the second top layer time, the difference of the voidage in the first top layer and intermediate layer is less than 5%, is more preferably less than 3%.By adjusting like this, homogeneous can be obtained and the high hard sheet of hardness.

It should be noted that, the difference of the voidage in the first top layer and intermediate layer is calculated by following formula.

Difference (the %)=absolute value (voidage (%) on voidage (%)-the first top layer in intermediate layer) of the voidage in the first top layer and intermediate layer

The voidage of each layer is obtained as follows.Utilize scanning electron microscope, take with 30 times of cross sections to the second composite thickness direction.Then, use image analysis software Popimaging (Digital beingkids.Co manufactures), with dynamic thresholding method, binaryzation carried out to the image of obtained photo, specific space part.And, describe inscribed circle, using the pore volume of the gross area of its inscribed circle as all layers at each space part.Then, use its photo, the part of 1/3 is divided into be set to from a surface in the second composite thickness direction the first top layer, to be divided into the part of 1/3 to be set to from another surface the second top layer, remaining layer is set to intermediate layer at thickness direction at thickness direction, the gross area of inscribed circle is obtained, as the pore volume of each layer according to each layer.Then, following formula is utilized to obtain the voidage of each layer.

Pore volume × 100 (%) of voidage=each layer pore volume/all layers of each layer

As making the second emulsion be impregnated in method in the first complex, make the method for its gelation and carry out the method for heat drying, can use with the method making the first emulsion impregnation, making the method for its gelation and carry out the same method of the method for heat drying.Form the second complex thus.

(5) wash the second complex, the total content of the ion that pH is changed is 400 μ g/cm ³following operation

As mentioned above, the hard sheet of present embodiment, when being imparted in nonwoven fabric by macromolecular elastomer, in order to suppress emulsion to the migration on top layer, uses the emulsion containing gelating agent.The discoveries such as the present inventor: when remaining ion contained in many gelating agents in the hard sheet obtained, when polishing, polishing velocity is reduced.And find: make the residual quantity of ion be 400 μ g/cm by washing ³time following, the reduction of polishing velocity can be suppressed.

The operation of carrying out washing is 400 μ g/cm with the total content of the ion making the pH of water change contained in hard sheet ³below, 350 μ g/cm are preferably become ³, preferably become 100 μ g/cm further ³following mode carries out the operation of washing.As method for washing, consider from washing efficiency height this respect, preference is as heating washing process.As concrete condition, such as, the second complex be impregnated in the hot water of more than 80 DEG C.Specifically, can enumerate in the following example as following condition: as the first stage, in the hot water of 65 ~ 90 DEG C, flood for 5 ~ 300 seconds, then carry out in the hot water of 85 ~ 100 DEG C, processing for 100 ~ 600 seconds as second stage.In addition, in order to improve washing efficiency, can carry out utilizing the extrusion process of roller, High-Pressure Water process, ultrasonic wave process as required, rinse process, stir process, rubbing process etc.

(6) in order to make the case hardness of hard sheet be JIS-D hardness more than 45, at least one being selected from the first complex, the second complex and hard sheet is carried out the operation of hot pressing

The space being present in hard sheet inside makes the uniformity of hardness and hardness reduce.In this operation, by the first above-mentioned complex, the second complex and/or hard sheet are carried out hot pressing, space is reduced.By making space reduce in this wise, the apparent density of hard sheet improves, and the uniformity of hardness, hardness and rigidity improve.As autoclaving conditions, utilize and be set to the temperature being heated to superfine fibre and macromolecular elastomer and not occurring to decompose, condition that the metallic roll being such as heated to 160 ~ 180 DEG C carries out pressurizeing with linear pressure 30 ~ 100kg/cm.

Through operation so above, the hard sheet of present embodiment can be obtained.The hard sheet of present embodiment preferably uses as the polishing layer of polishing pad.Specifically, can as required by forming polishing layer to the processing desired by hard sheet enforcement.Such as, the fluffing process implementing to utilize sand paper or pin cloth, diamond etc. to carry out or the brushing process of oppositely sealing, hot pressurized treatments or embossing processing etc.In addition, groove or the holes such as clathrate, concentric circles, swirling can be formed on the surface of hard sheet.

In addition, as required, can using hard sheet as elastomer layer laminations such as polishing layer and volume thing, fabric, nonwoven fabric, elastic resin film or elastic sponge bodies.As elastic membrane and elastic sponge body, except containing except the nonwoven fabric (such as " Suba400 " (Nitta Hass (strain) manufacture)) of polyurethane being soaked with current general use, can enumerate: the rubber such as natural rubber, acrylonitrile-butadiene rubber, polybutadiene rubber, silicon rubber; The thermoplastic elastomer (TPE)s such as polyester-type thermoplastic's elastomer, polyamide-type thermoplastic's elastomer, fluorine-containing thermoplastic elastomer (TPE); Foamed plastic; Polyurethane etc.Like this, by laminar flexible body layer, the local flat (local flat of wafer) of polished surface can be made to improve.It should be noted that, polishing pad is directly engaged by melting adhered etc. and except the polishing pad obtained, also comprised and utilize bonding agent or two-sided tape etc. by two-layer bonded polishing pad or the polishing pad that there is other layer further between the two layers except polishing layer and elastomer layer.

The polishing pad employing the hard sheet of present embodiment may be used for chemically mechanical polishing (CMP), and described chemically mechanical polishing (CMP) uses known CMP device and utilizes slurries to make polished surface contact certain hour with polishing pad with constant speed under elevated pressure.Slurries are such as containing water or the liquid medium of wet goods; The polishing agents such as silica, aluminium oxide, cerium oxide, zirconia, carborundum; The compositions such as alkali, acid, surfactant.In addition, when carrying out CMP, slurries and lubricating oil, cooling agent etc. can be combinationally used as required.

Article as polishing object are not particularly limited, and can enumerate such as: crystal, silicon, glass, optical substrate, electronic circuit board, multi-layer wire substrate, hard disk etc.As polishing object, be particularly preferably silicon wafer, semiconductor wafer.As the object lesson of semiconductor wafer, the semiconductor wafer of the barrier metal film such as the wiring material such as dielectric film, copper, aluminium, tungsten metal film, tantalum, titanium, tantalum nitride, titanium nitride such as on surface with silica, fluorinated silicon oxide, organic polymer etc. etc. can be enumerated.

Embodiment

Below, the present invention is illustrated by embodiment.It should be noted that, the present invention is not by any restriction of embodiment.

First, the evaluation method used in the present embodiment is summarized as follows is described.

[apparent density of hard sheet]

With the quality (g/cm of unit are hard sheet ²) value that obtains divided by thickness (cm) is as apparent density (g/cm ³).Then, apparent density is measured to any 10 places of hard sheet, carries out arithmetic average, using obtained value as apparent density.It should be noted that, thickness is at load 240gf/cm according to JISL1096 standard ²lower mensuration.

[mensuration of JIS-D hardness in the surface of hard sheet, the first top layer and intermediate layer and the calculating of R%]

The D hardness in the surface of hard sheet, the first top layer and intermediate layer according to JISK7311 standard test.Specifically, for the D hardness on hard sheet surface, thickness is about superimposed 8 of the hard sheet of 1.25mm, measures the hardness of 3 at width equably, using the D hardness of its mean value as hard sheet surface.

In addition, for the D hardness on the first top layer, ground from the second side, top layer by hard sheet thickness being about 1.25mm, obtain the sheet material on first top layer of thickness 0.40mm.Then, by superimposed for the sheet material on the first top layer obtained 25, measure the hardness of 3 equably at width, using the JIS-D hardness of its mean value as the first top layer.In addition, for the D hardness in intermediate layer, by being ground equably from the first side, top layer and the second side, top layer by hard sheet, obtain the sheet material in the intermediate layer of thickness 0.40mm.Then, by superimposed for the sheet material in the intermediate layer obtained 25, measure the hardness of 3 equably at width, using the hardness of its mean value as intermediate layer.And, use the value of the JIS-D hardness of the total 6 of the D hardness of 3 on the first top layer and the D hardness of 3 in intermediate layer obtained to obtain R (%) by following formula.

R (%)=(D maximum hardness-D hardness minimum of a value)/D hardness mean value × 100

[total content of the ion that the pH of water is changed]

The part and water 10mL that are cut into rectangular hard sheet are put into screw-cap test tube.Then, at 90 DEG C, 2 hours are heated to screw-cap test tube by block heater, the water-soluble substances in hard sheet has been carried out hot water extracting.Then, use chromatography of ions (ICS-1600) detects the ion component in its extract.Wherein, measure as the sulfate ion of the ion making the pH of water change and the total amount of ammonium ion, be scaled ionic weight contained in unit volume hard sheet.

[polishing velocity]

By hard sheet being cut into the toroidal of diameter 51cm, and clathrate ground is to be interposed between the groove that surface forms width 1.0mm, degree of depth 0.5mm between 15.0mm, made polishing pad thus.And, glue note adhesive tape at the back side of polishing pad, be then installed on CMP burnishing device (" PP0-60S " manufactured by Co., Ltd.'s wild village making).Then, at platen rotating speed 70 revs/min, rotary head rotating speed 69 revs/min, polish pressure 40g/cm ²condition under, the speed of dividing with 100ml/ supply slurries (the SHOROX A-31 that Showa Denko K. K manufactures) are while synthetic quartz polishing 3 hours to diameter 4 inches.And the thickness of any 25 in the face measuring the synthetic quartz after polishing, obtains polishing velocity (nm/ divides) by the average of the thickness in the polishing of each point institute divided by polishing time.

It should be noted that, measure the polishing velocity making thickness be about the hard sheet of the thickness 0.70mm that the first top layer of the hard sheet of 1.25mm and intermediate layer are exposed respectively.

[embodiment 1]

Use water-solubility PVA as sea component, use the isophthalate modified PET of modification degree 6 % by mole as island component.Water-solubility PVA and isophthalate modified PET are sprayed from melt composite spinning nozzle (island number: 25 islands/fiber) with 25/75 (mass ratio) at 260 DEG C.And adjustment injector pressure makes spinning speed be 3700m/min, at the long fiber of online trapping fiber number 3dtex, obtain weight per unit area 35g/m ²net.

Throw the net by cross layered and superimposed 16, made total weight per unit area 480g/m ²overlay network.And, overlay network is sprayed the finish preventing pin from bending.Then, barb number 1 is used and the knitting needle of No. 42, knitting yarn and barb number 6 and the knitting needle of No. 42, knitting yarn, by overlay network with 3150 pin holes/cm ²carry out needling treatment, resulting in obvolvent net.The weight per unit area of obvolvent net is 770g/m ², splitting power is 9.6kg/2.5cm.In addition, the percentage reduction of area obtained by needling treatment is 25.8%.

Then, by obvolvent net 110 DEG C, steam treatment 70 second under the condition of 23.5%RH.Percentage reduction of area is now 44%.Then, make its drying in the baking box of 90 ~ 110 DEG C after, then carry out hot pressing at 115 DEG C, obtain weight per unit area 1312g/m thus ², apparent density 0.544g/cm ³, thickness 2.41mm fiber obvolvent sheet.

Then, the emulsion as the polyurethane of the first emulsion is made to be impregnated in fiber obvolvent sheet.It should be noted that, polyurethane be mixture that the poly alkylene glycol of polycarbonate-based polyalcohol and carbon number 2 ~ 3 is mixed using 99.8:0.2 (mol ratio) as polyol component, and containing the carboxylic monomer of 1.5 quality % without xanthochromia type polyurethane.In addition, polyurethane is the polyurethane of the imporosity forming cross-linked structure by heat-treating.First emulsion is adjusted to: relative to polyurethane 100 parts by mass, and containing Carbodiimides crosslinking agent 4.6 parts by mass and ammonium sulfate 1.8 parts by mass as gelating agent, and the solid constituent of polyurethane is 20%.

By by containing the fiber obvolvent sheet being soaked with the first emulsion 90 DEG C, carry out heating under 30%RH atmosphere and make the first emulsion gel, at 150 DEG C, carried out dry process further.Then, then carry out hot pressing at 140 DEG C, be adjusted to weight per unit area 1403g/m thus ², apparent density 0.716g/cm ³, thickness 1.96mm.

Then, by utilizing extrusion process and High-Pressure Water process, there is the fiber obvolvent sheet of polyurethane to flood 10 minutes in the hot water of 95 DEG C imparting and dissolving removing water-solubility PVA, converting the superfine fibre of fiber number 0.09dtex to, then carry out drying.Thus, weight per unit area 1009g/m is obtained ², apparent density 0.538g/cm ³, thickness 1.87mm the first complex.

Then, the emulsion of the polyurethane as the second emulsion (solid constituent 30 quality %) is made to be impregnated in the first complex.It should be noted that, polyurethane is identical with the polyurethane of institute's impregnation above.Second emulsion is adjusted to: relative to polyurethane 100 parts by mass, and containing Carbodiimides crosslinking agent 4.6 parts by mass and ammonium sulfate 1.0 parts by mass, and the solid constituent of polyurethane is 30%.

By by containing the first complex being soaked with the second emulsion 90 DEG C, carry out heating under 60%RH atmosphere and make the second emulsion gel, then at 150 DEG C, carried out dry process.Thus, weight per unit area 1245g/m is obtained ², apparent density 0.748g/cm ³, thickness 1.66mm the second complex.The difference of the first top layer of the second complex and the voidage in intermediate layer is 1.8%.

Then, within 10 minutes, wash by using extrusion process and High-Pressure Water process to be flooded in the hot water of 95 DEG C by the second complex.Then, at 180 DEG C, drying has been carried out.And, by carrying out hot-pressing processing under linear pressure 100kg/cm, 160 DEG C of conditions, obtain weight per unit area 1212g/m ², apparent density 0.795g/cm ³, thickness 1.53mm the intermediate of hard sheet.

Use #100 paper to the top layer, two sides of hard sheet intermediate each grinding 0.15mm respectively, be finish-machined to weight per unit area 994g/m ², apparent density 0.788g/cm ³, thickness 1.26mm hard sheet.The JIS-D hardness of hard sheet is the R% of 52, JIS-D hardness is 11.3%.In addition, contained in the hard sheet sulfate ion as the ion making pH change and the total amount of ammonium ion are 26.9 μ g/cm ³.

Evaluation result is shown in table 1.

[embodiment 2]

Except carrying out, except hot-pressing processing, operating similarly to Example 1 to the first complex before imparting second emulsion under linear pressure 100kg/cm, 160 DEG C of conditions, manufacturing hard sheet and evaluating.It should be noted that, the weight per unit area of the hard sheet obtained is 996g/m ², apparent density is 0.808g/cm ³, thickness is 1.23mm.Show the result in table 1.

[embodiment 3]

Except reducing the washing degree of the second complex in embodiment 1, operate similarly to Example 1, manufacture hard sheet and evaluate.The sulfate ion as the ion making pH change contained in hard sheet and the total amount of ammonium ion are 300 μ g/cm ³.Show the result in table 1.

[comparative example 1]

Except not washing the second complex in embodiment 1, replace thus, by beyond the second complex is flooded in the hot water of 95 DEG C within 10 minutes, washing, operating similarly to Example 1, manufacturing hard sheet and also evaluate.Show the result in table 1.

[comparative example 2]

In embodiment 1, first complex has been carried out hot-pressing processing further under linear pressure 100kg/cm, 160 DEG C of conditions, then, impregnation is not containing the emulsion of the same composition of gelating agent, impregnation is replaced to contain the second emulsion of gelating agent thus, in addition, operate similarly to Example 1, manufacture hard sheet and evaluate.It should be noted that, the weight per unit area of the hard sheet obtained is 969g/m ², apparent density is 0.817g/cm ³, thickness is 1.19mm.Show the result in table 1.

[comparative example 3]

Except reducing the washing degree of the second complex in embodiment 1, operate similarly to Example 1, manufacture hard sheet and evaluate.The sulfate ion as the ion making pH change contained in hard sheet and the total amount of ammonium ion are 404 μ g/cm ³.Show the result in table 1.

[comparative example 4]

Except reducing the washing degree of the second complex in embodiment 1, operate similarly to Example 1, manufacture hard sheet and evaluate.The sulfate ion as the ion making pH change contained in hard sheet and the total amount of ammonium ion are 504 μ g/cm ³.Show the result in table 1.

As shown in Table 1, for the JIS-D of employing hardness of the present invention be more than 45, R% is 0 ~ 20%, the total content of ion that the pH of water is changed is 400 μ g/cm ³the polishing pad of the hard sheet that following embodiment 1 ~ 3 obtains, the polishing velocity on its first top layer, i.e. initial burnishing speed are 120nm/ and divide, and the mean value after 5 hours can keep more than 90% of initial burnishing speed.On the other hand, in the second emulsion, gelating agent is coordinated and for the polishing pad not carrying out the hard sheet of the comparative example 1 of fully washing, the polishing velocity on its first top layer is obviously lower, for 93nm/ divides for employing.In addition, the hard sheet of comparative example 2 is the homogenising of being sought hard sheet by hot pressing, replaces thus in the second emulsion, coordinate gelating agent to carry out the elastomeric example of filled high polymer equably.For the polishing pad of comparative example 2, the total content of ion is few, but R% is 30.2% and uneven.Its result, the mean value after 5 hours only can keep 89% of initial burnishing speed.In addition, the total content of ion is 404 μ g/cm ³comparative example 3 and 504 μ g/cm ³comparative example 4, the mean value after 5 hours all can only keep about 84% of initial burnishing speed.

Claims (16)

1. a hard sheet, its nonwoven fabric comprising the superfine fibre with 0.0001 ~ 0.5dtex fiber number and the macromolecular elastomer be imparted in described nonwoven fabric,

The JIS-D hardness of described hard sheet is more than 45,

To cross section 3 deciles equably of thickness direction, and from any one face side each layer after 3 deciles is set to successively the first top layer, intermediate layer and the second top layer time,

Measure the JIS-D hardness of any 3 totals 6 separately in described first top layer and described intermediate layer, use the D hardness of total 6, the R% calculated by following formula is 0 ~ 20%,

Mean value × 100 of R (%)=(D maximum hardness-D hardness minimum of a value)/D hardness

Further, the total content of the ion making the pH of water change is 400 μ g/cm ³below.

2. hard sheet according to claim 1, wherein, the total content of described ion is 1 ~ 100 μ g/cm ³.

3. hard sheet according to claim 1, wherein, described superfine fibre is long fiber, and forms fibre bundle.

4. hard sheet according to claim 3, wherein, the apparent density of described nonwoven fabric is 0.35 ~ 0.90g/cm ³.

5. hard sheet according to claim 3, wherein, in the cross section of thickness direction, formed the described superfine fibre of described fibre bundle at least partially by described macromolecular elastomer boundling.

6. hard sheet according to claim 5, wherein, in the cross section of thickness direction, the mutual at least partially of described fibre bundle is bondd by described macromolecular elastomer.

7. hard sheet according to claim 3, wherein, in the cross section of thickness direction, forms the radical more than half of the described superfine fibre of described fibre bundle by described macromolecular elastomer boundling.

8. hard sheet according to claim 7, wherein, in the cross section of thickness direction, the bundle more than half of described fibre bundle is bondd by described macromolecular elastomer each other.

9. hard sheet according to claim 1, wherein, described macromolecular elastomer is non-porous macromolecular elastomer.

10. hard sheet according to claim 1, wherein, the mass ratio (nonwoven fabric/macromolecular elastomer) of described nonwoven fabric and described macromolecular elastomer is 90/10 ~ 55/45.

11. hard sheets according to claim 10, its apparent density is 0.50 ~ 1.2g/cm ³.

12. hard sheets according to claim 1, wherein, the JIS-D hardness on described second top layer is more than 45,

Measure the JIS-D hardness of any 3 totals 6 separately in described second top layer and described intermediate layer, use the D hardness of total 6, the R% calculated by following formula is 0 ~ 20%,

R (%)=(D maximum hardness-D hardness minimum of a value)/D hardness mean value × 100.

13. 1 kinds of polishing pads, it possesses hard sheet according to any one of claim 1 ~ 12 as polishing layer.

The manufacture method of 14. 1 kinds of hard sheets, the method comprises following operation:

(1) operation of the long stapled fiber obvolvent sheet of superfine fibre generation fiber type is prepared, the long stapled fiber obvolvent sheet of described superfine fibre generation fiber type can form the nonwoven fabric of the superfine fibre with below 0.5dtex fiber number by superfine fibre process, and the apparent density of described nonwoven fabric is 0.35g/cm ³above;

(2) the first emulsion containing gelating agent and macromolecular elastomer is made to be impregnated in described fiber obvolvent sheet, then the first emulsion gel is made, carry out heat drying again, make the operation that macromolecular elastomer solidifies thus, described gelating agent contains the ion that the pH of water is changed;

(3) by carrying out superfine fibre process to described superfine fibre generation fiber type, the operation of the first complex containing described nonwoven fabric and described macromolecular elastomer is formed;

(4) the second emulsion containing described gelating agent and described macromolecular elastomer is made to be impregnated in described first complex, carry out heat drying again, described macromolecular elastomer is made to solidify thus, thus form the operation of the second complex, described second complex is carried out 3 deciles equably at thickness direction, and from any one face side each layer after 3 deciles is set to successively the first top layer, intermediate layer and the second top layer time, the difference of the voidage in described first top layer and described intermediate layer is less than 5%;

(5) described second complex is washed, make the total content of described ion be 400 μ g/cm ³below, thus obtain the operation of hard sheet; And

(6) in order to make the case hardness of described hard sheet be JIS-D hardness more than 45, at least one being selected from described first complex, described second complex and described hard sheet is carried out the operation of hot pressing.

The manufacture method of 15. hard sheets according to claim 14, wherein, the total content of described ion is 1 ~ 100 μ g/cm ³.

The manufacture method of 16. hard sheets according to claim 14, wherein, described superfine fibre generation fiber type is the islands-in-sea bicomponent fibre comprising the water insoluble thermoplastic polyvinyl alcohol resin as sea component, the water-insoluble thermoplastic resin as island component

The superfine fibre process of described operation (3) is the operation making described water insoluble thermoplastic polyvinyl alcohol resin be dissolved in warm water and optionally remove.