JP2024068757A - Double-sided adhesive tape for fixing abrasive members, multi-layered polishing pad, method for fixing a top pad to a surface plate, and method for fixing a multi-layered polishing pad to a surface plate - Google Patents

Abstract

To provide a double-sided adhesive tape which is hardly displaced or peeled off even at high temperature in polishing, and has performance that is easily peeled off after polishing.SOLUTION: A double-sided adhesive tape for fixing a polishing member comprises a film base material, an acrylic first adhesive layer, and a natural rubber-based second adhesive layer, and is used (1) for fixing a top pad to a cushion layer or (2) for fixing the top pad to a surface plate or fixing a cushion layer of a multilayer type polishing pad to the surface plate, wherein a difference in thickness between the first adhesive layer and the second adhesive layer is 25 μm or less, thickness of the film base material is 20 μm or more and less than 75 μm, in the case of (1), the first adhesive layer is brought into contact with the top pad, and the second adhesive layer is brought into contact with the cushion layer, in the case of (2), the first adhesive layer is brought into contact with the top pad, and the second adhesive layer is brought into contact with the surface plate, and in the case of (3), the first adhesive layer is brought into contact with the cushion layer, and the second adhesive layer is brought into contact with the surface plate.SELECTED DRAWING: None

Description

The present invention relates to a double-sided adhesive tape for fixing an abrasive member, which is used when polishing objects such as silicon wafers, glass (for liquid crystal, reinforced), hard disks, etc. More specifically, the present invention relates to a double-sided adhesive tape for fixing a top pad to a cushion layer, fixing a top pad to a surface plate, or fixing the cushion layer of a multi-layer type polishing pad having a top pad and a cushion layer to a surface plate.
The present invention also relates to a multi-layer type polishing pad in which a top pad is fixed to a cushion layer by a double-sided adhesive tape for fixing a polishing member.
Furthermore, the present invention relates to a method for fixing a top pad to a platen, and a method for fixing a cushion layer of a multi-layer type polishing pad to a platen.

When polishing the surface of a polishing target, a polishing method and apparatus are known in which a top pad or a multi-layer polishing pad is attached to a polishing machine platen using a double-sided adhesive tape. It is also known to form a multi-layer type polishing pad by attaching a top pad and a cushion layer using a double-sided adhesive tape.
Patent Document 1 describes a double-sided pressure-sensitive adhesive tape having an acrylic pressure-sensitive adhesive layer on one side of a substrate and a rubber pressure-sensitive adhesive layer on the other side of the substrate.
Patent Document 2 describes a double-sided pressure-sensitive adhesive tape having a thermal adhesive layer containing 40 to 100% by mass of a thermoplastic elastomer on one side of a substrate, and an acrylic pressure-sensitive adhesive layer or a rubber pressure-sensitive adhesive layer on the other side of the substrate.

JP 2012-057135 A JP 2013-213192 A

During polishing, the top pad, multi-layer polishing pad, double-sided adhesive tape used for attachment, and surface plate may become hot. In recent years, from the viewpoint of cost reduction and high efficiency, polishing pads are increasingly used for longer periods of time than before in order to reduce the time required to replace polishing pads. In addition, polishing time may be shortened by increasing the temperature and pressure during polishing.
The double-sided adhesive tape used for attachment is subjected to shear forces during polishing, and the double-sided adhesive tape must be able to withstand the application without shifting from its original position or peeling off during polishing.
On the other hand, when the top pad or multi-layer polishing pad is peeled off from the platen together with the double-sided adhesive tape after polishing is completed, it is required that the adhesive layer does not remain on the surface of the platen. In other words, the double-sided adhesive tape is required to have the performance of being resistant to slippage and peeling, and the performance of being easy to peel off.

The present invention aims to provide a double-sided adhesive tape that is resistant to slippage or peeling even at high temperatures during polishing, yet is easy to peel off after polishing.

The present inventors have conducted extensive research to solve the above problems and have arrived at the present invention.
[1]
A double-sided adhesive tape for fixing an abrasive member, comprising a film substrate, a first adhesive layer located on one side of the film substrate, and a second adhesive layer located on the other side of the film substrate,
The difference in thickness between the first adhesive layer and the second adhesive layer is 25 μm or less;
The thickness of the film substrate is 20 μm or more and less than 75 μm,
the first adhesive layer is an acrylic adhesive layer formed from an acrylic adhesive containing an acrylic copolymer formed from an acrylic monomer containing 60% by weight or more of butyl (meth)acrylate and a tackifier resin;
the second adhesive layer is a natural rubber-based adhesive layer formed from a natural rubber-based adhesive containing natural rubber, an inorganic oxide, and a tackifier resin;
A double-sided adhesive tape for fixing an abrasive member according to any one of the following (1) to (3):
(1) A double-sided adhesive tape for fixing an abrasive member, for fixing a top pad to a cushion layer. (2) A double-sided adhesive tape for fixing an abrasive member, for fixing a top pad to a surface plate. (3) A double-sided adhesive tape for fixing an abrasive member, for fixing the cushion layer of a multi-layer type abrasive pad having a top pad and a cushion layer to a surface plate. In the case of (1) above, the first adhesive layer contacts the top pad, the second adhesive layer contacts the cushion layer,
In the case of (2) above, the first adhesive layer is in contact with the top pad, and the second adhesive layer is in contact with the base plate;
In the case of (3) above, the first adhesive layer is in contact with the cushion layer, and the second adhesive layer is in contact with the base plate.
Double-sided adhesive tape for fixing abrasive materials.

[2] The double-sided adhesive tape for fixing an abrasive member described in [1] above, in which the thickness of the second adhesive layer is thinner than the thickness of the first adhesive layer.

The double-sided adhesive tape for fixing abrasive members described in [1] or [2] above, in which the natural rubber-based adhesive contains 3 to 80 parts by mass of inorganic oxide per 100 parts by mass of natural rubber.

[4] The double-sided adhesive tape for fixing an abrasive member according to any one of [1] to [3] above, in which the natural rubber-based adhesive contains 30 to 180 parts by mass of a tackifier resin per 100 parts by mass of the total of the natural rubber and the inorganic oxide.

[5] The double-sided adhesive tape for fixing abrasive members according to claim 3 in any one of [1] to [4] above, wherein the natural rubber-based adhesive contains a polyterpene resin as a tackifier resin.

[6] The double-sided adhesive tape for fixing an abrasive member according to any one of [1] to [5] above, wherein the acrylic adhesive contains 40 to 100% by mass of terpene phenol resin in 100% by mass of tackifier resin.

[7] The double-sided adhesive tape for fixing an abrasive member according to any one of [1] to [6] above, wherein the acrylic adhesive contains 40 to 70 parts by mass of a tackifier resin per 100 parts by mass of the acrylic copolymer.

[8] A multi-layer polishing pad in which a top pad is fixed to a cushion layer using the double-sided adhesive tape for fixing a polishing member described in any one of [1] to [7] above.

[9] A method for fixing a top pad to a base plate using the double-sided adhesive tape for fixing an abrasive member described in any one of [1] to [7] above.

[10] A method for fixing a multi-layer type polishing pad having a top pad and a cushion layer to a platen using the double-sided adhesive tape for fixing a polishing member described in any one of [1] to [7] above.

When the double-sided adhesive tape for fixing abrasive members of the present invention is used as a double-sided adhesive tape for fixing a top pad to a cushion layer, a double-sided adhesive tape for fixing a top pad to a base plate, or a double-sided adhesive tape for fixing the cushion layer of a multi-layer type polishing pad having a top pad and a cushion layer to a base plate, the shear force applied during polishing is not biased unilaterally toward the adhesive layer, which has weak cohesive strength, so there is no slippage or peeling, and after polishing is completed, the top pad or multi-layer type polishing pad can be peeled off without leaving the adhesive layer on the base plate.

The double-sided adhesive tape for fixing an abrasive member of the present invention comprises a film substrate, a first adhesive layer located on one side of the film substrate, and a second adhesive layer located on the other side of the film substrate.
The double-sided adhesive tape for fixing an abrasive member of the present invention is also called a double-sided adhesive sheet for abrasion or a double-sided adhesive film for abrasion.

[First adhesive layer (acrylic adhesive layer)]
The first adhesive layer will be described.
The first adhesive layer is an acrylic adhesive layer formed from an acrylic adhesive containing a tackifier resin and an acrylic copolymer formed from an acrylic monomer containing 60 parts by weight or more of butyl (meth)acrylate.

<Acrylic Monomer>
The acrylic monomer includes (meth)acrylic acid alkyl esters as so-called "functional group-free" acrylic monomers. "Functional group-free" here means that functional groups other than (meth)acryloyl groups are not included. The acrylic monomer includes 60% by weight or more of butyl acrylate, which is an acrylic monomer "having no functional group," and may further include (meth)acrylic acid alkyl esters other than butyl acrylate "having no functional group" (meth)acrylate, and other monomers having functional groups such as carboxyl groups and hydroxyl groups.
In the present invention, the proportion of butyl (meth)acrylate in 100% by weight of the acrylic monomers for forming the acrylic copolymer is 60% by weight or more, more preferably 80% by weight or more. By being in this range, it becomes possible to provide a well-balanced combination of adhesive strength and cohesive strength suitable for a double-sided adhesive tape for fixing an abrasive member.
As the butyl (meth)acrylate, butyl acrylate is preferred, and n-butyl acrylate is more preferred.

<"Having no functional group" (meth)acrylic acid alkyl ester (other than butyl (meth)acrylate)>
Examples of (meth)acrylic acid alkyl esters other than butyl (meth)acrylate that have no functional group include:
For example, methyl (meth)acrylate, ethyl (meth)acrylate, isobutyl (meth)acrylate, propyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, lauryl (meth)acrylate, and the like.

<Monomer having a carboxy group>
In addition, the acrylic copolymer in the present invention preferably has a carboxy group. By using an acrylic copolymer having a carboxy group and blending a curing agent described later, it becomes easy to introduce a structure that makes it easy to control the crosslink density into the acrylic adhesive layer, and it is easy to balance the adhesive strength and cohesive strength.
From the above viewpoint, it is preferable to use 1 to 9% by weight, and more preferably 2 to 8% by weight, of the monomer having a carboxyl group in 100% by weight of the acrylic monomer. Examples of the monomer having a carboxyl group include (meth)acrylic acid, itaconic acid, maleic acid, etc., with (meth)acrylic acid being preferred, and acrylic acid being more preferred. The monomer is not limited to these monomers, and may be used alone or in combination of two or more.

<Monomer having a hydroxy group>
In the present invention, the acrylic copolymer may have a hydroxy group within the range that satisfies the required performance. The acrylic copolymer having a hydroxy group can be formed, for example, by copolymerizing 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, etc. The monomer having a hydroxy group is not limited to these monomers, and may be used alone or in combination of two or more kinds.
In addition, by not copolymerizing a monomer having a hydroxy group with butyl (meth)acrylate, it is possible to reduce dense cross-linking between polymers and increase the adhesive strength to an adherend such as a top pad.

<Other Monomers>
In the present invention, an acrylic copolymer obtained by copolymerizing (meth)acrylamide, vinyl acetate, acrylonitrile, or the like can also be used within a range that satisfies the required performance.

<Acrylic copolymer>
The acrylic copolymer used in the present invention can be polymerized by a polymerization method such as solution polymerization, emulsion polymerization, bulk polymerization, or polymerization by ultraviolet irradiation. In the present invention, it is preferable to use solution polymerization, which is easy to control the reaction and physical properties.

In the present invention, for the copolymerization, a conventionally known polymerization initiator such as a peroxide-based polymerization initiator or an azobis-based polymerization initiator can be used.
Examples of the organic peroxide polymerization initiator include benzoyl peroxide, di-t-butyl peroxide, cumene hydroperoxide, t-butyl peroxybenzoate, t-butyl peroxy neodecanoate, and t-butyl peroxy 2-ethylhexanoate.
Examples of the azobis-based polymerization initiator include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-amidinopropane) dihydrochloride, 2,2'-azobis[2-(5-methyl-2-imidazolin-2-yl)propane] dihydrochloride, 2,2'-azobis(2-methylpropionamidine) disulfate, and 2,2'-azobis(N,N'-dimethyleneisobutylamidine).
These polymerization initiators may be used alone or in combination of two or more kinds.

The weight average molecular weight of the acrylic copolymer used in the present invention is preferably 300,000 to 1,500,000, and more preferably 400,000 to 1,200,000. By setting it within this range, it becomes possible to provide a well-balanced combination of adhesive strength and cohesive strength suitable for the double-sided pressure-sensitive adhesive sheet for polishing.
In the present invention, the weight average molecular weight is the weight average molecular weight calculated as polystyrene by GPC measurement, and the GPC measurement conditions are as follows: Apparatus: Shimadzu Prominence (manufactured by Shimadzu Corporation), column: TOSOH TSK-GEL GMHXL (manufactured by Tosoh Corporation), solvent: tetrahydrofuran, flow rate: 0.5 ml/min, temperature: 40° C., sample concentration: 0.1 wt %, sample injection amount: 100 μl

<Tackifier resin contained in first adhesive layer>
As described above, the first adhesive layer is formed from an acrylic adhesive containing an acrylic copolymer and a tackifier resin. From the viewpoint of improving the cohesive strength of the formed acrylic adhesive layer, the acrylic adhesive preferably contains 40 to 70 parts by mass, more preferably 40 to 60 parts by mass, of the tackifier resin per 100 parts by mass of the acrylic copolymer. When the double-sided adhesive tape for fixing an abrasive member of the present invention is used to fix a top pad to a cushion layer, it is important that the acrylic adhesive layer having a high cohesive strength is used on the top pad side, which is more likely to be exposed to high temperatures during polishing. In addition, when the double-sided adhesive tape for fixing an abrasive member of the present invention is used to fix a top pad to a platen, it is important that the acrylic adhesive layer having a high cohesive strength is used on the top pad side, not the platen side. In addition, when the double-sided adhesive tape for fixing an abrasive member of the present invention is used to fix a multi-layer type polishing pad to a platen, it is important that the acrylic adhesive layer having a high cohesive strength is used on the cushion layer side, not the platen side.
The cohesive strength of the adhesive layer is generally measured and evaluated as a holding force.

Examples of tackifier resins include rosin-based resins such as rosin ester, polymerized rosin, hydrogenated rosin, disproportionated rosin, maleic acid modified rosin, fumaric acid modified rosin, and rosin phenolic resin;
Terpene resins such as α-pinene resins, β-pinene resins, dipentene resins, polyterpene resins, aromatic terpene resins (terpene phenol resins, styrenated terpene resins), hydrogenated terpene resins, and acid-modified terpene resins;
Petroleum-based hydrocarbon resins such as C5 aliphatic hydrocarbon resins, C9 aromatic hydrocarbon resins, hydrogenated C9 hydrocarbon resins, C5-C9 copolymer resins, and dicyclopentadiene hydrocarbon resins;
Examples of the resin include coumarone-indene resin, styrene resin, alkylphenol resin, and xylene resin.
The tackifier resin is not limited to these, and may be used alone or in combination of two or more kinds. From the viewpoint of the balance between adhesion and heat resistance, however, terpene resins are preferred, and terpene phenol resins are more preferred.
The terpene phenol resin is contained in an amount of preferably 40 to 100 mass %, more preferably 60 to 100 mass %, and even more preferably 80 to 100 mass %, relative to 100 mass % of the tackifier resin.

Terpene phenol resins include, for example,
Kraton's SylVares series: TP95 (softening point 95±5°C, hereinafter the same), TP105 (105±5°C), TP115 (115±5°C),
Examples of such polyesters include U115 (softening point 115±5°C, hereinafter the same) T80 (80±5°C), T100 (100±5°C), T115 (115±5°C), T130 (130±5°C), and T145 (145±5°C) from the YS Polystar series manufactured by Yasuhara Chemical Co., Ltd.

The acrylic adhesive for forming the first adhesive layer may further include a curing agent capable of reacting with a functional group of the acrylic copolymer. It is preferable to introduce a crosslinked structure into the first adhesive layer by the reaction between the acrylic copolymer and the curing agent from the viewpoint of improving the cohesive strength of the first adhesive layer.
Examples of the curing agent include isocyanate-based compounds, epoxy-based compounds, aziridinyl-based compounds, and organic compounds of metals, with isocyanate-based compounds being preferred.
The amount of the curing agent is preferably 1 part by weight or more and 5 parts by weight or less, and more preferably 1 part by weight or more and 3 parts by weight or less, based on 100 parts by weight of the acrylic copolymer.

Furthermore, in the present invention, the acrylic adhesive for forming the first adhesive layer may contain various additives such as fillers, pigments, dyes, diluents, polymerization inhibitors, UV absorbers, UV stabilizers, coupling agents, etc., which are blended with known adhesives as necessary, and two or more types may be used. Furthermore, the amount of additives added is not particularly limited as long as it is an amount that provides the required physical properties.

[Second adhesive layer (natural rubber-based adhesive layer)]
The second adhesive layer will be described.
The second adhesive layer is a natural rubber-based adhesive layer formed from a natural rubber-based adhesive containing natural rubber, an inorganic oxide, and a tackifier resin. In the natural rubber-based adhesive of the present invention, a synthetic rubber can be used in combination with the natural rubber as necessary within a range that does not impair the required performance.

<Natural rubber>
Examples of natural rubber include RSS (Ribbed Smoked Sheet) and TSR (Technically Specified Rubber). Examples of RSS include RSS No. 1, RSS No. 2, RSS No. 3, RSS No. 4, and RSS No. 5, and examples of TSR include TSRCV, TSRL, TSR5, TSR10, TSR20, and TSR50, but the natural rubber is not limited to these and can be used as needed within a range that does not impair the required performance, and two or more types may be used in combination.
Furthermore, natural rubber can be masticated using a mastication roll depending on the required performance before use.

<Inorganic oxide>
The inorganic oxide has a function of imparting cohesive strength to the natural rubber adhesive layer. Examples of the inorganic oxide include zinc oxide, magnesium oxide, titanium oxide, silicon oxide, and lead oxide, with zinc oxide being preferred.
The natural rubber-based adhesive preferably contains 3 to 80 parts by mass, more preferably 5 to 70 parts by mass, and even more preferably 10 to 50 parts by mass of inorganic oxide per 100 parts by mass of natural rubber.
The natural rubber-based adhesive is preferably obtained by adding an inorganic oxide to natural rubber and kneading the mixture to obtain an intermediate having a ML(1+4), Mooney viscosity at 100°C of about 30,000 to 100,000, and then blending a tackifier resin, etc., described below, with the intermediate.

<Tackifier resin contained in second adhesive layer>
As described above, the second adhesive layer is formed from a natural rubber-based adhesive containing natural rubber, an inorganic oxide, and a tackifier resin. From the viewpoint of improving the cohesive strength of the formed natural rubber-based adhesive layer, the natural rubber-based adhesive preferably contains 30 to 180 parts by mass, and more preferably 50 to 150 parts by mass, of the tackifier resin per 100 parts by mass of the total of the natural rubber and the inorganic oxide.
Examples of tackifier resins include rosin-based resins such as rosin ester, polymerized rosin, hydrogenated rosin, disproportionated rosin, maleic acid modified rosin, fumaric acid modified rosin, and rosin phenolic resin;
Terpene resins such as α-pinene resins, β-pinene resins, dipentene resins, polyterpene resins, aromatic terpene resins (terpene phenol resins, styrenated terpene resins), hydrogenated terpene resins, and acid-modified terpene resins;
Petroleum-based hydrocarbon resins such as C5 aliphatic hydrocarbon resins, C9 aromatic hydrocarbon resins, hydrogenated C9 hydrocarbon resins, C5-C9 copolymer resins, and dicyclopentadiene hydrocarbon resins;
Examples of the resin include coumarone-indene resin, styrene resin, alkylphenol resin, and xylene resin.
The tackifier resin is not limited to these, and may be used alone or in combination of two or more. As the tackifier resin, terpene resin is preferable from the viewpoint of improving adhesion to low polarity adherends and improving chemical resistance to water-based polishing slurry aqueous solution, and polyterpene resin is more preferable. In addition, it is preferable to use rosin resin in combination from the viewpoint of adhesion to polishing members, and hydrogenated rosin ester is preferable as the rosin resin. The polyterpene resin is preferably contained in 40 to 100 mass%, more preferably contained in 50 to 90 mass%, and even more preferably contained in 60 to 80 mass% of 100 mass% of the tackifier resin.

Examples of polyterpene resins include:
Kraton's SylVares series: TRB115 (softening point 115°C, hereinafter the same), TRB1115T (115°C), TR7115 (115°C), TRM1115 (115°C), TR7125 (softening point 125°C), TRB125 (softening point 125°C), TRB1135 (135°C), TR90 (90°C), TR105 (softening point 105°C),
Examples of such resins include PX1250 (softening point 125°C, hereinafter the same), PX1150 (115°C), PX1000 (100°C), and PX800 (80°C) from the YS Resin series manufactured by Yasuhara Chemical Co., Ltd.
These tackifier resins may be used alone or in combination of two or more kinds.

Since natural rubber often has functional groups such as carboxyl groups, hydroxyl groups, amino groups, etc., the natural rubber-based adhesive for forming the second adhesive layer may further contain a curing agent capable of reacting with the functional groups. From the viewpoint of improving the cohesive strength of the second adhesive layer, it is preferable to introduce a crosslinked structure into the second adhesive layer by the reaction between the natural rubber and the curing agent.
Examples of the curing agent include isocyanate-based compounds, epoxy-based compounds, aziridinyl-based compounds, and organic compounds of metals, with isocyanate-based compounds being preferred.
The amount of the curing agent is preferably 1 part by weight or more and 30 parts by weight or less, and more preferably 5 parts by weight or more and 25 parts by weight or less, based on 100 parts by weight of natural rubber.

Furthermore, in the present invention, the natural rubber adhesive for forming the second adhesive layer may contain various additives such as fillers, pigments, dyes, diluents, polymerization inhibitors, UV absorbers, UV stabilizers, coupling agents, etc., which are blended with known adhesives as necessary, and two or more types may be used. Furthermore, the amount of additives added may be an amount that provides the required physical properties, and is not particularly limited.

When the double-sided adhesive tape for fixing abrasive members of the present invention is used to fix a top pad to a cushion layer, it is important that the natural rubber-based adhesive layer is used on the cushion layer side, which is less likely to be exposed to high temperatures during polishing. In addition, when the double-sided adhesive tape for fixing abrasive members of the present invention is used to fix a top pad to a base plate or a multi-layer type polishing pad to a base plate, by using a natural rubber-based adhesive layer on the base plate side, the top pad can be peeled off together with the double-sided adhesive tape from the base plate after polishing without leaving any adhesive layer behind.

[Double-sided adhesive tape for fixing abrasive members]
The double-sided adhesive tape for fixing an abrasive member of the present invention is a double-sided adhesive tape comprising a film substrate, a first adhesive layer located on one side of the film substrate, and a second adhesive layer located on the other side of the film substrate, and the difference in thickness between the first adhesive layer and the second adhesive layer is 25 μm or less, preferably 20 μm or less, and more preferably 15 μm or less. By setting the difference in thickness between the first adhesive layer and the second adhesive layer within the above range, excellent cohesion (holding force) for abrasive use can be obtained.
The thickness of each of the first and second adhesive layers is preferably 10 to 100 μm, more preferably 20 to 80 μm, and even more preferably 30 to 70 μm, and it is particularly preferable that the second adhesive layer is thinner than the first adhesive layer. By making the second adhesive layer thinner than the first adhesive layer, the cohesive force (holding force) of the second adhesive layer can be made greater.

<Film substrate>
The film substrate, which is located between the first and second adhesive layers and is used as a support for both adhesive layers, may be a plastic film.
Examples of the plastic film include films made of polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate, PPS (polyphenylene sulfide), nylon, triacetyl cellulose, cycloolefins, polyimides, polyamides, and the like.
The surface of the film substrate may be subjected to an easy-adhesion treatment to enhance adhesion with the adhesive layer. The easy-adhesion treatment may be a known method such as a dry method of performing corona discharge or a wet method of applying an anchor coating agent. Of the film substrates, it is more preferable to use a film with easy-adhesion treated surfaces on both sides. By using a film with easy-adhesion treated surfaces, it is possible to obtain a double-sided adhesive tape that has improved adhesion with the adhesive layer and is less likely to leave adhesive residue on the surface plate.
An antistatic layer can be formed on the film substrate by coating the surface of the film substrate with a composition containing conductive carbon particles, conductive metal particles, a conductive polymer, etc., or by subjecting the surface of the film substrate to metal deposition or metal plating.

As the film substrate becomes thinner, the adhesive strength (peeling strength) to the cushion layer increases.
By using a double-sided adhesive tape for fixing a polishing member having a thin film substrate to fix a top pad to a cushion layer to form a multi-layered polishing pad, it is expected that the cushioning properties of the cushion layer will be utilized more than by using a thick film substrate. Similarly, by using a double-sided adhesive tape for fixing a polishing member having a thin film substrate to fix the cushion layer of a multi-layered polishing pad having a top pad and a cushion layer to a platen, it is expected that the cushioning properties of the multi-layered polishing pad will be utilized more.
On the other hand, as the film substrate becomes thicker, the adhesive strength (peeling strength) to the base plate increases. However, on the other hand, when the top pad or multi-layer polishing pad is peeled off from the base plate after polishing is completed, an adhesive layer (hereinafter sometimes abbreviated to "glue") is likely to remain on the base plate. Therefore, a thinner film substrate is preferable in terms of preventing glue from remaining behind.
Therefore, in the present invention, it is important that the thickness of the film substrate is 20 μm or more and less than 75 μm, and it is preferably 20 μm or more and 50 μm or less.

The double-sided pressure-sensitive adhesive tape for fixing an abrasive member of the present invention can be produced, for example, by the following method (A) or (B).
(A) An acrylic adhesive and a natural rubber adhesive are each coated onto a release liner to form a first adhesive layer and a second adhesive layer, and then the first adhesive layer and the second adhesive layer are bonded to each side of a film substrate.
(B) Either an acrylic adhesive or a natural rubber adhesive is applied to one surface of a film substrate to form a first adhesive layer or a second adhesive layer, and the other adhesive layer is formed by separately applying the other adhesive layer, either the acrylic adhesive or the natural rubber adhesive, to a release liner, and the other adhesive layer formed on the release liner is attached to the surface of the film substrate on the side on which no adhesive layer is formed.
Incidentally, the adhesive layer is usually protected with a release liner until immediately before the adhesive tape is used.

The release liner has a release layer formed by applying a release agent to a substrate such as paper, plastic film, or synthetic paper. Examples of release agents include silicone, alkyd resin, melamine resin, fluororesin, and acrylic resin. The removable adhesive of the present invention has the effect of making the release force less dependent on the type of release agent. There is no particular limit to the thickness of the release liner, but it is about 10 to 200 μm.

The adhesive can be applied by known methods such as the roll coater method, comma coater method, lip coater method, die coater method, reverse coater method, silk screen method, gravure coater method, etc. After application, it can be dried using a hot air oven, infrared heater, etc.

As described above, the double-sided adhesive tape for fixing an abrasive member of the present invention can be used in three main ways.
That is,
(1) Used to fix the top pad to the cushion layer to form a multi-layer type polishing pad;
(2) Used to secure the top pad to the base plate.
(3) It is used to fix the cushion layer of a multi-layer polishing pad having a top pad and a cushion layer to a platen.

The top pad, also called polishing cloth, is a member that comes into direct contact with the object to be polished during polishing, and examples of such pads include hard polyurethane sheets, synthetic leather, suede, velour, etc. The top pad may be used as a single layer fixed to a surface plate as in the above-mentioned (2), or may be bonded to a cushion layer to form the outermost surface of a multi-layer type polishing pad.
Examples of the cushion layer include foams and nonwoven fabrics. Examples of the foams include urethane foams, polyethylene foams, polypropylene foams, etc. Examples of the nonwoven fabrics include those made from polyester, etc., and those made from natural materials such as wool, etc.
In the case of (3) above, the multi-layer type polishing pad used may be one formed using the double-sided adhesive tape for fixing abrasive members of the present invention, or it may be one formed using another double-sided adhesive tape.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples. In the examples, "parts" means "parts by weight" and "%" means "% by weight."

<Synthesis Example 1: Acrylic Copolymer (A-1)>
In a four-neck flask equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen inlet tube, 47.5 parts by weight of butyl acrylate, 2.5 parts by weight of acrylic acid, ethyl acetate as a solvent, and appropriate amounts of azobisisobutyronitrile as an initiator were charged under a nitrogen atmosphere.
Separately, 47.5 parts by weight of butyl acrylate, 2.5 parts by weight of acrylic acid, ethyl acetate as a solvent, and appropriate amounts of azobisisobutyronitrile as an initiator were charged into a dropping tube.
The flask was then gradually heated, and after the start of the reaction was confirmed, the solution was added dropwise from the dropping tube over 1 hour. The reaction was further continued for 8 hours at an internal temperature of about 80° C. After the reaction was completed, the flask was cooled, and an appropriate amount of ethyl acetate was added to obtain an acrylic copolymer (A-1) having a weight average molecular weight of 600,000.

<Synthesis Examples 2 to 3: Acrylic Copolymers (A-2) and (A-3)>
Acrylic copolymers (A-2) and (A-3) were obtained in the same manner as in Synthesis Example 1, except that the monomer compositions were changed to those shown in Table 1. The monomer compositions shown in Table 1 are the total amounts placed in the flask and the dropping tube.

<Formulation Example 1: Acrylic adhesive>
An acrylic adhesive was obtained by blending 100 parts by mass of the acrylic copolymer (A-1) with 40 parts by mass of YS Polystar T130 (manufactured by Yasuhara Chemical Co., Ltd., terpene phenol resin, softening point 130°C) as a tackifier resin and 1.5 parts by mass of a TDI-TMP adduct (3 moles of tolylene diisocyanate to 1 mole of trimethylolpropane) as an isocyanate compound as a curing agent.

<Formulation Examples 2 to 4: Acrylic Adhesive>
According to the formulation shown in Table 2, an acrylic pressure sensitive adhesive was obtained in the same manner as in Formulation Example 1.

<Formulation Example 11: Natural Rubber-Based Adhesive>
100 parts by mass of natural rubber SSR1 was masticated several times with a mastication roller while 15 parts by mass of zinc oxide was mixed therein to obtain an intermediate having a Mooney viscosity of 45,000.
Then, in a four-neck flask equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen inlet tube, the intermediate was charged with appropriate amounts of methyl ethyl ketone, toluene, and Gomuuki G as a solvent under a nitrogen atmosphere. The flask was then gradually heated to an internal temperature of about 50° C. for 3 hours to obtain a uniform dispersion.
The obtained dispersion was cooled to an internal temperature of about 40°C or less, and 60 parts by mass of YS Resin PX1150 (manufactured by Yasuhara Chemical Co., Ltd., polyterpene resin, softening point 115°C) as a tackifier resin, 25 parts by mass of Ester Gum H (manufactured by Arakawa Chemical Industries, Ltd., hydrogenated rosin ester, softening point 68 to 75°C) and 2 parts by weight of Irgaphos 168 (manufactured by BASF Japan) as an anti-aging agent were added, diluted with methyl ethyl ketone and toluene, and stirring was continued until the tackifier resin was dissolved, to obtain a base material for a natural rubber-based adhesive with a non-volatile content of 23% and a viscosity of 17,000 mPa·s.
A natural rubber-based adhesive was obtained by blending 20 parts by mass of a TDI-TMP adduct, which is an isocyanate compound, as a curing agent with 100 parts by mass of the natural rubber contained in the base material.

<Composition Examples 12 to 13: Natural Rubber-Based Adhesives>
According to the formulation shown in Table 3, a natural rubber-based pressure-sensitive adhesive was obtained in the same manner as in Formulation Example 11.

<Formulation Example 14: Natural Rubber-Based Adhesive>
As shown in Table 3, a natural rubber-based pressure-sensitive adhesive was obtained in the same manner as in Compounding Example 11, except that 100 parts by mass of natural rubber SSR1 was masticated without adding zinc oxide.

The abbreviations in Tables 1 to 3 are as follows.
BA: n-butyl acrylate 2EHA: 2-ethylhexyl acrylate AA: acrylic acid

YS Polystar T130 (manufactured by Yasuhara Chemical Co., Ltd., terpene phenol resin, softening point 130°C)
YS Resin PX1150 (Yasuhara Chemical Co., Ltd., polyterpene resin, softening point 115°C)
Ester gum H (Arakawa Chemical Industries, hydrogenated rosin ester, softening point 68-75°C)
Pencel D125 (Arakawa Chemical Industries, Ltd., polymerized rosin ester, softening point 120-130°C)

TDI-TMP adduct: an isocyanate compound in which toluene diisocyanate is added to trimethylolpropane

<Preparation of adhesive sheet>
The acrylic adhesive of Formulation Example 1 was applied to a 25 μm polyethylene terephthalate (hereinafter referred to as PET) film substrate so that the thickness after drying would be 50 μm, and after drying at 100° C. for 2 minutes, a release liner was attached.
Separately, the natural rubber-based adhesive of Formulation Example 11 was applied to another release liner so that the thickness after drying would be 50 μm, and then dried at 100° C. for 2 minutes.
Next, the obtained natural rubber adhesive layer was attached to the side of the PET film on which the acrylic adhesive layer was not provided, and left for one week at 23°C-50% to obtain a double-sided adhesive sheet of Example 1. The adhesive strength, holding power, and adhesive residue after a water immersion test were evaluated by the methods described below. The results are shown in Table 4.

[Examples 2-3], [Comparative Example 1]
Double-sided PSA sheets were obtained in the same manner as in Example 1, except that the natural rubber-based PSA of Formulation Example 11 was replaced with the natural rubber-based PSA of Formulation Examples 12 to 14 as shown in Table 4, and evaluated in the same manner.

[Example 4], [Comparative Examples 2 to 3]
Double-sided PSA sheets were obtained and evaluated in the same manner as in Example 1, except that the acrylic PSA of Formulation Example 1 was replaced with the acrylic PSA of Formulation Examples 2 to 4 as shown in Table 5. Example 1 is also shown in Table 5.

[Examples 5 to 7]
Double-sided PSA sheets were obtained and evaluated in the same manner as in Example 1, except that the thicknesses of the acrylic adhesive layer and the natural rubber adhesive layer were changed as shown in Table 6. Table 6 also shows the results of Example 1.

[Examples 8 to 9], [Comparative Example 4]
Double-sided PSA sheets were obtained and evaluated in the same manner as in Example 1, except that the thicknesses of the acrylic adhesive layer and the natural rubber adhesive layer were set as shown in Table 7. Table 7 also shows Example 1.

[Examples 10 to 11], [Comparative Example 5]
Double-sided PSA sheets were obtained and evaluated in the same manner as in Example 1, except that the thicknesses of the acrylic adhesive layer and the natural rubber adhesive layer were set as shown in Table 8. Example 2 is also shown in Table 8.

[Example 12], [Comparative Examples 6 to 7]
Double-sided PSA sheets were obtained and evaluated in the same manner as in Example 1, except that the thickness of the film substrate was changed as shown in Table 9. Note that Example 1 is also shown in Table 9.

[Evaluation method]
<Adhesive strength of first adhesive layer to top pad>
The release liner on the second adhesive layer side of the obtained adhesive sheet was peeled off, and a 25 μm thick PET film was attached as a backing, and then the sheet was cut to a size of 25 mm wide and 100 mm long to prepare a sample.
Next, in an atmosphere of 23°C-50%RH, the opposite side of the obtained sample to the side on which the PET film for backing was attached, i.e., the release liner covering the first adhesive layer, was peeled off, and the exposed first adhesive layer was placed on a top pad, and a 2 kg roller was rolled back and forth once to temporarily bond the first adhesive layer, and then the first adhesive layer was bonded with a pressure roller under conditions of a temperature of 90°C, a speed of 3.0 M/min, and a pressure of 0.3 MPa, and the test piece was left for 24 hours in an atmosphere of 23°C-50%RH. The adhesive strength of the test piece was measured under the same environment using a tensile tester at a peel angle of 180 degrees and a peel speed of 300 mm/min. A hard polyurethane sheet was used as the top pad.

<Adhesive strength of first adhesive layer and second adhesive layer to cushion layer>
The release liner on the second adhesive layer side of the obtained adhesive sheet was peeled off, and a 25 μm thick PET film was attached as a backing, and then the sheet was cut to a size of 25 mm wide and 100 mm long to prepare a sample.
Next, in an atmosphere of 23°C-50%RH, the side opposite to the side on which the backing PET film was attached, i.e., the release liner covering the first adhesive layer, was peeled off from the obtained sample, the exposed first adhesive layer was placed on the cushion layer, and a 2 kg roller was rolled back and forth once to temporarily bond the layers, and then the layers were bonded with a pressure roller under conditions of a temperature of 90°C, a speed of 3.0 M/min, and a pressure of 0.3 MPa, and the layers were left for 24 hours in an atmosphere of 23°C-50%RH to obtain a test piece. The adhesive strength of the test piece was measured under the same environment using a tensile tester at a peel angle of 180° and a peel speed of 300 mm/min.
The adhesive strength of the second adhesive layer was also measured in the same manner. Note that a urethane foam sheet was used as the cushion layer.

<Adhesive strength of second adhesive layer to stainless steel plate>
The release liner on the first adhesive layer side of the obtained adhesive sheet was peeled off, and a 25 μm thick PET film was attached as a backing, and then the sheet was cut to a size of 25 mm wide and 100 mm long to prepare a sample.
Next, in an atmosphere of 23°C-50% RH, the side opposite to the side on which the backing PET film was attached, i.e., the release liner covering the second adhesive layer, was peeled off from the obtained sample, and the exposed second adhesive layer was placed on a stainless steel plate and pressed with a 2 kg roller once, and then left in the same environment for 24 hours to obtain a test piece. The adhesive strength of the test piece was measured in the same environment using a tensile tester at a peel angle of 180° and a peel speed of 300 mm/min.

In addition, for practical purposes, the adhesive strength of the first adhesive layer and the second adhesive layer is required to be at least 20 N with respect to the top pad and the cushion layer.
In addition, in Tables 4 to 9, the adherends, that is, the top pad, the cushion layer, and the stainless steel plate, are described as PAD, cushion, and SUS, respectively.

<Holding power>
The same sample as in the adhesive strength measurement was prepared, and the release liner was peeled off by 25 mm from the end of the 100 mm length. An area of 25 mm length x 25 mm width was placed on the top pad, the cushion layer, and the stainless steel plate, respectively, and pressed against each other by a 2 kg roller going back and forth once, and then left for 20 minutes in an atmosphere of 23°C -50%.
Thereafter, in an atmosphere of 80°C, a 1 kg weight was attached to the lower end of the 100 mm long sample so that a force was applied in a 180 degree direction, and after 24 hours, the number of millimeters by which the adhesion position shifted from the adherend, or the number of seconds it took for the sample to fall completely, was measured for each of the first adhesive layer and the second adhesive layer, and evaluated according to the following criteria.
・First adhesive layer to top pad 〇: Less than 1.0 mm ×: 1.0 mm or less ・(First adhesive layer or second adhesive layer) to cushion layer ◎: 20,000 seconds or more Excellent 〇: 10,000 seconds or more but less than 20,000 seconds Good △: 5,000 seconds or more but less than 10,000 seconds Passable ×: Less than 5,000 seconds Unacceptable ・Second adhesive layer to stainless steel plate 〇: 10,000 seconds or more ×: Less than 10,000 seconds

<Adhesive residue after water immersion test>
A sample was prepared in the same manner as in the adhesive strength measurement, and immediately after the second adhesive layer was pressed onto the stainless steel plate, the test piece together with the stainless steel plate was immersed in warm water at 40°C. After 24 hours, the test piece was removed from the warm water and washed with water. Then, the second adhesive layer was peeled off from the stainless steel plate under the same conditions as in the adhesive strength measurement, and the surface of the stainless steel plate was observed to confirm the presence or absence of any adhesive layer residue.
◯: No residue was left behind (good)
△: A slight residue was observed (no problem in practical use) ×: Residue remained (unusable)

As shown in Tables 4 to 9, the first adhesive layer in the double-sided adhesive tape of each Example exhibits excellent adhesion to the top pad and cushion layer, and the second adhesive layer exhibits excellent adhesion to the cushion layer and stainless steel plate. Moreover, the first adhesive layer in the double-sided adhesive tape of each Example exhibits excellent holding power to the top pad and cushion layer at high temperatures, and the second adhesive layer exhibits excellent holding power to the cushion layer and stainless steel plate at high temperatures. Furthermore, the second adhesive layer in the double-sided adhesive tape of each Example can be peeled off without leaving any adhesive layer residue on the stainless steel plate after a water immersion test.
On the other hand, the double-sided pressure-sensitive adhesive tapes of each comparative example were inferior in any one of the performance against the top pad and cushion layer of the first adhesive layer, the cushion layer of the second adhesive layer, and the performance against the stainless steel plate.

[Example 2 ], [Reference Example 3] , [Comparative Example 1]
Double-sided PSA sheets were obtained and evaluated in the same manner as in Example 1, except that the natural rubber PSA of Blending Example 11 was replaced with the natural rubber PSA of Blending Examples 12 to 14 as shown in Table 4. Note that Example 3 in Table 4 refers to Reference Example 3.

[Examples 5-6] , [Reference Example 7]
A double-sided PSA sheet was obtained and evaluated in the same manner as in Example 1, except that the thicknesses of the acrylic adhesive layer and the natural rubber adhesive layer were changed as shown in Table 6. Example 1 is also shown in Table 6. Example 7 in Table 6 means Reference Example 7.

Claims (10)

A double-sided adhesive tape for fixing an abrasive member, comprising a film substrate, a first adhesive layer located on one side of the film substrate, and a second adhesive layer located on the other side of the film substrate,
The difference in thickness between the first adhesive layer and the second adhesive layer is 25 μm or less;
The thickness of the film substrate is 20 μm or more and less than 75 μm,
the first adhesive layer is an acrylic adhesive layer formed from an acrylic adhesive containing an acrylic copolymer formed from an acrylic monomer containing 60% by weight or more of butyl (meth)acrylate and a tackifier resin;
the second adhesive layer is a natural rubber-based adhesive layer formed from a natural rubber-based adhesive containing natural rubber, an inorganic oxide, and a tackifier resin;
A double-sided adhesive tape for fixing an abrasive member according to any one of the following (1) to (3):
(1) A double-sided adhesive tape for fixing an abrasive member, for fixing a top pad to a cushion layer. (2) A double-sided adhesive tape for fixing an abrasive member, for fixing a top pad to a surface plate. (3) A double-sided adhesive tape for fixing an abrasive member, for fixing the cushion layer of a multi-layer type abrasive pad having a top pad and a cushion layer to a surface plate. In the case of (1) above, the first adhesive layer contacts the top pad, the second adhesive layer contacts the cushion layer,
In the case of (2) above, the first adhesive layer is in contact with the top pad, and the second adhesive layer is in contact with the base plate;
In the case of (3) above, the first adhesive layer is in contact with the cushion layer, and the second adhesive layer is in contact with the base plate.
Double-sided adhesive tape for fixing abrasive materials. The double-sided adhesive tape for fixing an abrasive member according to claim 1, wherein the thickness of the second adhesive layer is thinner than the thickness of the first adhesive layer. The double-sided adhesive tape for fixing abrasive members according to claim 1 or 2, wherein the natural rubber-based adhesive contains 3 to 80 parts by mass of inorganic oxide per 100 parts by mass of natural rubber. The double-sided adhesive tape for fixing abrasive members according to claim 3, wherein the natural rubber-based adhesive contains 30 to 180 parts by mass of a tackifier resin per 100 parts by mass of the total of the natural rubber and inorganic oxide. The double-sided adhesive tape for fixing abrasive members according to claim 3, wherein the natural rubber adhesive contains a polyterpene resin as a tackifier resin. The double-sided adhesive tape for fixing abrasive members according to claim 1 or 2, wherein the acrylic adhesive contains 40 to 100% by mass of terpene phenol resin in 100% by mass of tackifier resin. The double-sided adhesive tape for fixing an abrasive member according to claim 6, wherein the acrylic adhesive contains 40 to 70 parts by mass of a tackifier resin per 100 parts by mass of the acrylic copolymer. A multi-layer polishing pad in which a top pad is fixed to a cushion layer using the double-sided adhesive tape for fixing a polishing member according to claim 1. A method for fixing a top pad to a surface plate using the double-sided adhesive tape for fixing an abrasive member according to claim 1. A method for fixing a multi-layer type polishing pad having a top pad and a cushion layer to a platen using the double-sided adhesive tape for fixing a polishing member according to claim 1.