JP4606010B2 - Radiation-curable re-peelable water-dispersible acrylic pressure-sensitive adhesive composition and radiation-cured re-peelable acrylic pressure-sensitive adhesive sheet - Google Patents

Description

  The present invention relates to a radiation-curing re-peelable acrylic pressure-sensitive adhesive sheet used for surface protection and damage prevention in the manufacture of microfabricated parts such as semiconductors, circuits, various printed boards, various masks, and lead frames, and the like. The present invention relates to a radiation-curable water-removable acrylic pressure-sensitive adhesive composition for use in a pressure-sensitive adhesive layer of a pressure-sensitive adhesive sheet. In particular, the present invention relates to a radiation-curing re-peelable acrylic pressure-sensitive adhesive sheet that is preferably used as a pressure-sensitive adhesive sheet for processing semiconductor wafers used when grinding or dicing a semiconductor wafer. Further, the present invention relates to a method for processing an adherend using the radiation-curing / removable acrylic pressure-sensitive adhesive sheet.

  A semiconductor wafer containing silicon, gallium, arsenic, or the like as a raw material is manufactured in a large-diameter state, then cut and separated (diced) into element pieces, and further transferred to a mounting process. At this time, the semiconductor wafer is usually diced in a state of being attached to an adhesive sheet, and then the steps of washing, expanding, and pick-up are added to the mounting step. In a process from a dicing process of a semiconductor wafer to a pick-up process, an adhesive sheet having a configuration in which an adhesive is applied on a base made of a plastic film has been used as an adhesive sheet.

  In such a semiconductor wafer manufacturing method, in the dicing process, it is required that the cut and separated element pieces are not peeled off from the adhesive sheet, and therefore the adhesive sheet is required to have high adhesiveness. ing. On the other hand, in the pickup process, the element piece must be easily peeled off from the adhesive sheet, and the adhesive sheet is required to have low adhesiveness. In order to control these two contradictory adhesive properties (adhesiveness), a radiation-curing / removable acrylic adhesive sheet is used. In other words, the radiation-curing re-peelable acrylic pressure-sensitive adhesive sheet has high adhesiveness before radiation curing, and exhibits the characteristics that the element small pieces do not peel off from the pressure-sensitive adhesive sheet, while the pressure-sensitive adhesive is cured by radiation irradiation. After that, low adhesiveness is obtained, and the characteristic that the element piece is easily peeled off from the adhesive sheet is exhibited.

  In such applications, various types of acrylic pressure-sensitive adhesive sheets in which an acrylic polymer is used as the pressure-sensitive adhesive component of the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer are disclosed as radiation-curable re-peelable acrylic pressure-sensitive adhesive sheets ( Patent Literature 1 to Patent Literature 2). As such an acrylic polymer, what was synthesize | combined and prepared in the organic solvent is used.

  Thus, conventionally, a solvent-type acrylic pressure-sensitive adhesive has been used as the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer. However, the solvent-type acrylic pressure-sensitive adhesive is synthesized in an organic solvent and contains an organic solvent, and the solvent volatilizes during the application of the pressure-sensitive adhesive when producing a pressure-sensitive adhesive sheet, which is environmentally problematic. There is a demand for conversion to water-dispersed acrylic adhesives.

  On the other hand, as water-dispersed acrylic pressure-sensitive adhesives, various pressure-sensitive adhesives have been proposed. For example, they are not water-dispersed acrylic pressure-sensitive adhesives for radiation curable re-peeling, but by emulsion polymerization using reactive emulsifiers. An acrylic emulsion adhesive obtained has been proposed (see Patent Documents 3 to 4). Conventional acrylic emulsion adhesives manufactured using reactive emulsifiers are not water-dispersed acrylic adhesives for radiation-curing re-peeling. Therefore, it does not have a function of easily peeling the element piece from the adhesive sheet. The reason why the reactive emulsifier is used as the emulsifier is to reduce contamination of the semiconductor wafer as the adherend.

  In addition, as a radiation curable pressure sensitive adhesive sheet, there is proposed a radiation curable pressure sensitive adhesive sheet in which a pressure sensitive adhesive containing an acrylic polymer obtained by emulsion polymerization using an anionic emulsifier (non-reactive anionic emulsifier) is used. (See Patent Document 5).

JP 60-189938 A JP-A-60-196956 Japanese Patent Laid-Open No. 4-186732 JP-A-6-322338 JP 7-193032 A

  As described above, as a radiation-curable pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive containing an acrylic polymer obtained by emulsion polymerization using an anionic emulsifier is used, disclosed in Example 4 described in JP-A-7-193032. However, as an emulsifier, a non-reactive anionic emulsifier which is a general anionic emulsifier is used. Therefore, compared to a solvent-type acrylic pressure-sensitive adhesive, an emulsifier is used. The adhesion to the wafer is low. Therefore, in the dicing process, there may be a problem that the element piece cut and separated is peeled off from the adhesive sheet.

Therefore, even if the object of the present invention is a water-dispersed acrylic pressure-sensitive adhesive composition, the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition has a property that can be re-peeled by radiation irradiation. In addition, the present invention is to provide a radiation curable re-peeling water-dispersible acrylic pressure-sensitive adhesive composition and a radiation curable re-peelable acrylic pressure-sensitive adhesive sheet that can exhibit excellent tackiness before irradiation with radiation.
Another object of the present invention is that the adhesiveness to the element small piece is good before irradiation, and the element small piece can be easily peeled off again after irradiation, which is useful as an adhesive sheet for processing semiconductor wafers. Another object of the present invention is to provide a radiation-curable re-peelable acrylic pressure-sensitive adhesive sheet.
Still another object of the present invention is to provide a method for processing an adherend using the radiation-curing / removable acrylic pressure-sensitive adhesive sheet.

  As a result of intensive studies to achieve the above object, the present inventors have found that even if a water-dispersed acrylic pressure-sensitive adhesive composition is used, the types of monomer components and emulsifiers used in preparing an acrylic emulsion polymer, radiation, etc. By controlling the types and proportions of the components used to exhibit the function of re-peeling by irradiation treatment, the adhesiveness until re-peeling can be improved, and re-peeling easily by radiation irradiation It has been found that a radiation-curable re-peelable acrylic pressure-sensitive adhesive sheet can be obtained. In particular, when a radically polymerizable polyfunctional monomer for radiation curing is used as an aqueous dispersion prepared using a specific dispersant, it is possible to improve the water-resistant adhesion of the radiation-curing re-peelable acrylic pressure-sensitive adhesive sheet. I found it. The present invention has been completed based on these findings.

That is, the present invention relates to an acrylic emulsion-based polymer obtained by emulsion polymerization using a monomer component (A1) mainly composed of an alkyl (meth) acrylate and a reactive emulsifier (A2) having a radical polymerizable functional group. The polymer (A) contains a radiation-curing radical polymerizable polyfunctional monomer (B), and the radiation-curing radical polymerizable polyfunctional monomer (B) contains a polymer having a weight average molecular weight of 8000 or more. The polymer composition is blended as an aqueous dispersion dispersed in water using a polymer dispersing agent, and the ratio of the radiation-curable radical polymerizable polyfunctional monomer (B) is 100% of the acrylic emulsion polymer (A) 100. A radiation-curable water-dispersible acrylic pressure-sensitive adhesive composition for re-peeling, characterized in that it is 20 to 200 parts by weight with respect to parts by weight.

  In the radiation curable re-peeling water-dispersible acrylic pressure-sensitive adhesive composition of the present invention, the gel fraction after heat treatment is preferably 20 to 60% by weight.

  The present invention also provides a radiation curable re-peelable acrylic pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer made of the radiation-curable re-peelable water-dispersible acrylic pressure-sensitive adhesive composition. In such a radiation-curing re-peelable acrylic pressure-sensitive adhesive sheet, the adhesive force to the mirror surface of the silicon mirror wafer (23 ° C. × 50% RH atmosphere, 180 ° peel, tensile speed 300 mm / min) is 4.5 N / min. It is 20 mm or more, and the adhesive force (23 ° C. × 50% RH atmosphere, 180 ° peeling, tensile speed 300 mm / min) to the mirror surface of the silicon mirror wafer after radiation irradiation treatment is 0.1 N / 20 mm or less. Is preferred. The radiation-curing re-peelable acrylic pressure-sensitive adhesive sheet can be suitably used as a pressure-sensitive adhesive sheet for semiconductor wafer processing.

  Furthermore, the present invention is a method of processing an adherend using the radiation-curing / removable acrylic pressure-sensitive adhesive sheet, wherein the adherend is bonded to the radiation-curing / removable acrylic pressure-sensitive adhesive sheet, In a method of processing an adherend characterized by peeling the adherend subjected to the processing treatment from the radiation-curing re-peelable acrylic pressure-sensitive adhesive sheet by subjecting the adherend to a treatment treatment by radiation irradiation treatment. is there.

  According to the radiation-curable re-peeling water-dispersible acrylic pressure-sensitive adhesive composition of the present invention, since it has the above-described configuration, even if it is a water-dispersed acrylic pressure-sensitive adhesive composition, the pressure-sensitive adhesive composition The pressure-sensitive adhesive layer formed by the method has a property that can be re-peeled by irradiation, and can exhibit excellent adhesiveness before irradiation. Radiation-curable re-peelable acrylic pressure-sensitive adhesive sheet prepared using such a radiation-curable re-peelable water-dispersed acrylic pressure-sensitive adhesive composition is particularly suitable for semiconductor wafer processing used when grinding or dicing semiconductor wafer backside It can be suitably used as a pressure-sensitive adhesive sheet, and interface shearing does not occur between an aluminum surface and a gold wire in wire bonding performed at the time of manufacturing a semiconductor chip, and high shear strength can be maintained. Furthermore, in various applications involving the peeling of the adhesive sheet at the time of use or at the end of use, for example, in the manufacture of various industrial parts, particularly finely processed parts such as semiconductors, circuits, various printed boards, various masks, lead frames, etc. It can be widely used as a radiation-curing re-peelable acrylic pressure-sensitive adhesive sheet used for surface protection and damage prevention.

  The radiation curable re-peeling water-dispersible acrylic pressure-sensitive adhesive composition of the present invention comprises a monomer component (A1) mainly composed of (meth) acrylic acid alkyl ester, and a reactive emulsifier (A2) having a radical polymerizable functional group. ) And an acrylic emulsion polymer (A) obtained by emulsion polymerization using a radical polymerization polyfunctional monomer (B) for radiation curing. Moreover, the ratio of the said radiation-curable radically polymerizable polyfunctional monomer (B) is 20-200 weight part with respect to 100 weight part of said acrylic emulsion type polymers (A). That is, in the radiation curable re-peeling water-dispersible acrylic pressure-sensitive adhesive composition of the present invention, a specific acrylic emulsion polymer (A) is used as the main component of the resin component, and it is cured by radiation irradiation treatment. Radiation-curing radically polymerizable polyfunctional monomer (B) is used at a specific ratio as a radiation-curing monomer as a component that exhibits properties. Therefore, even if the radiation-curable re-peeling water-dispersed acrylic pressure-sensitive adhesive composition is a water-dispersed acrylic pressure-sensitive adhesive composition, the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition is exposed to radiation. It has re-peelable properties and can exhibit excellent adhesiveness before irradiation. Of course, since a water-dispersed acrylic pressure-sensitive adhesive is used instead of a solvent-type acrylic pressure-sensitive adhesive, it is environmentally superior.

[Acrylic emulsion polymer (A)]
As described above, the acrylic emulsion polymer (A) is a monomer component (A1) mainly composed of (meth) acrylic acid alkyl ester [sometimes simply referred to as “monomer component (A1)”], An acrylic emulsion polymer prepared by emulsion polymerization using a reactive emulsifier (A2) having a radical polymerizable functional group (sometimes referred to simply as “reactive emulsifier (A2)”). The acrylic emulsion polymer (A) can be used alone or in combination of two or more.

The monomer component (A1) contains (meth) acrylic acid alkyl ester as the main monomer, and contains other monomer (copolymerizable monomer) copolymerizable with the (meth) acrylic acid alkyl ester as necessary. May be. Examples of the (meth) acrylic acid alkyl ester include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, (meth) Isobutyl acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, isoamyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, Octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate , Undecyl (meth) acrylate, dodecyl (meth) acrylate, (me ) Tridecyl acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, nonadecyl (meth) acrylate, (meth) Examples thereof include (meth) acrylic acid C _1-20 alkyl (linear or branched alkyl) esters such as eicosyl acrylate. The (meth) acrylic acid alkyl ester can be appropriately selected according to the intended tackiness and the like. The (meth) acrylic acid alkyl ester can be used alone or in combination of two or more.

  In the present invention, as described above, in addition to the main monomer, if necessary, stabilization of emulsion particles, improvement in adhesion of the pressure-sensitive adhesive layer to the support (base material), and initial adhesion to the adherend For the purpose of improving adhesiveness, a copolymerizable monomer can be used in combination. This copolymerizable monomer is in the range of 60% by weight or less (preferably 40% by weight or less, more preferably 25% by weight or less) in the total amount of all monomer components (monomer mixture), depending on the type of each monomer in the monomer mixture. The usage amount can be appropriately selected.

  Examples of copolymerizable monomers include (meth) acrylic acid (acrylic acid, methacrylic acid), itaconic acid, maleic acid, fumaric acid, crotonic acid, carboxyethyl acrylate, carboxypentyl acrylate, and other carboxyl group-containing monomers; maleic anhydride Acid, acid anhydride group-containing monomers such as isotonic anhydride; (meth) acrylic acid alicyclic hydrocarbon esters such as cyclohexyl (meth) acrylate, bornyl (meth) acrylate, isobornyl (meth) acrylate; ) (Meth) acrylic acid aryl esters such as phenyl acrylate; vinyl esters such as vinyl acetate and vinyl propionate; styrene monomers such as styrene; epoxy group-containing monomers such as glycidyl (meth) acrylate; acrylic acid 2- Hydroxyethyl, acrylic acid 2 Hydroxyl group-containing monomers such as hydroxypropyl; (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-butyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methylolpropane (meth) acrylamide, (meth) acryloylmorpholine, aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, (meth) acrylic acid t -Nitrogen atom-containing monomers such as butylaminoethyl; alkoxy group-containing monomers such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate; cyano group-containing monomers such as acrylonitrile and methacrylonitrile; ethylene, Olefinic monomers such as lopyrene, isoprene, butadiene, isobutylene; vinyl ether monomers such as vinyl ether, N-vinylpyrrolidone, methylvinylpyrrolidone, vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole , Vinyl group-containing heterocyclic compounds such as vinyl oxazole and vinyl morpholine, and N-vinyl carboxylic acid amides.

  Examples of copolymerizable monomers include maleimide monomers such as N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, and N-phenylmaleimide; N-methylitaconimide, N-ethylitaconimide, N-butyl Itaconimide monomers such as itaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, N-laurylitaconimide; N- (meth) acryloyloxymethylene succinimide, N- (meth) acryloyl Succinimide monomers such as -6-oxyhexamethylene succinimide and N- (meth) acryloyl-8-oxyoctamethylene succinimide; styrene sulfonic acid, allyl sulfonic acid, 2- ( T) Acrylamide-2-methylpropane sulfonic acid, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth) acrylate, (meth) acryloyloxynaphthalene sulfonic acid-containing monomer such as 2-hydroxyethyl acryloyl phosphate Phosphoric group-containing monomers; glycol-based acrylic ester monomers such as (meth) acrylic acid polyethylene glycol, (meth) acrylic acid polypropylene glycol, (meth) acrylic acid methoxyethylene glycol, (meth) acrylic acid methoxypolypropylene glycol; (meth) Acrylic acid containing a heterocyclic ring such as tetrahydrofurfuryl acrylate, fluorine (meth) acrylate, silicone (meth) acrylate, halogen atom or silicon atom Such ester monomers may also be used.

  Furthermore, as the copolymerizable monomer, a polyfunctional monomer can be used for adjusting the gel fraction of the adhesive composition. Examples of polyfunctional monomers include (mono or poly) ethylene glycol di (meth) acrylate such as ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, and tetraethylene glycol di (meth) acrylate. In addition to (mono or poly) alkylene glycol di (meth) acrylate such as (mono) polypropylene glycol di (meth) acrylate such as (meth) acrylate and propylene glycol di (meth) acrylate, neopentyl glycol di (meta) ) Acrylate, 1,6-hexanediol di (meth) acrylate, pentaerythritol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) Acrylate, dipentaerythritol hexa (meth) acrylate, and divinylbenzene. Moreover, epoxy acrylate, polyester acrylate, urethane acrylate, etc. can also be used as a polyfunctional monomer.

  In the present invention, the acrylic emulsion polymer (A) preferably has a radically polymerizable carbon-carbon double bond in the side chain or main chain of the polymer or at the terminal of the main chain of the polymer. Can be used. Thus, the acrylic emulsion polymer (A) having a radically polymerizable carbon-carbon double bond, for example, has a main chain when having a radically polymerizable carbon-carbon double bond in the side chain of the polymer. Copolymerization using an epoxy group-containing monomer [such as glycidyl (meth) acrylate] as a monomer component constituting the monomer component, and further a monomer component having a carboxyl group or a derivative group thereof (such as an acid anhydride group) [for example, (Meth) acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, carboxyethyl acrylate, carboxypentyl acrylate and other carboxyl group-containing monomers; maleic anhydride, itaconic anhydride and other acid anhydride group-containing monomers, etc.] Use the epoxy group and the carboxyl group or the group of its derivative (an acid anhydride group etc. By reacting the door, it can be prepared.

  In addition, since the (meth) acrylic acid alkyl ester is used as the main component of the monomer component (A1), the proportion is preferably 50% by weight or more based on the total amount of the monomer component (A1), but 40% by weight. % Or more. The (meth) acrylic acid alkyl ester is preferably 60% by weight or more (particularly 75% by weight or more) based on the total amount of the monomer component (A1). In addition, the upper limit of the content ratio of the (meth) acrylic acid alkyl ester is not particularly limited, and is, for example, 100% by weight (preferably 99% by weight, more preferably 98% by weight) with respect to the total amount of the monomer component (A1). There may be. When the content ratio of the (meth) acrylic acid alkyl ester is too low, an adhesive that exhibits good peeling force and cohesive force may not be obtained.

  The reactive emulsifier (A2) has a function as an emulsifier and has a radically polymerizable functional group (for example, radically polymerizable carbon such as ethenyl group, propenyl group, allyl group and allyl ether group) in the molecule. A group having a carbon double bond). In particular, since the radiation-curable radically polymerizable polyfunctional monomer (B) for radiation curing is contained in the radiation-curable re-peeling water-dispersible acrylic pressure-sensitive adhesive composition of the present invention, the reactive emulsifier (A2) is: It also has a function of increasing the adhesive strength before the radiation treatment by interaction with the radically polymerizable polyfunctional monomer (B) for radiation curing. That is, in the past, reactive emulsifiers were used to reduce contamination on the adherend, but in the present invention, reactive emulsifiers also have their functions, but the adhesive before radiation treatment is used. It is important to have a function to increase power. Therefore, the pressure-sensitive adhesive composition of the present invention differs from the conventional pressure-sensitive adhesive composition not only in its configuration but also in its effect.

  Examples of the reactive emulsifier (A2) include various emulsifiers (for example, nonionic anionic reactive emulsifier, anionic emulsifier, nonionic emulsifier, etc.) and radical polymerizable functional groups (radical reactive groups) such as propenyl group and allyl ether group. And a reactive emulsifier having a form in which () is introduced (or corresponding to the form). The reactive emulsifier (A2) can be used alone or in combination of two or more.

  When the reactive emulsifier (A2) is a nonionic anionic reactive emulsifier having a radical polymerizable functional group having a form in which a radical polymerizable functional group is introduced into the nonionic anionic emulsifier (or corresponding to the form), Examples of the nonionic anionic emulsifier include sodium polyoxyethylene alkyl ether sulfate, ammonium polyoxyethylene alkyl phenyl ether sulfate, sodium polyoxyethylene alkyl phenyl ether sulfate, sodium polyoxyethylene alkyl sulfosuccinate and the like. In addition, as such a nonionic anion emulsifier, it is desirable that the average added mole number of ethylene oxide or propylene oxide is 30 or less (preferably 20 or less, more preferably 15 or less).

  In the present invention, the nonionic anionic emulsifier means an anionic emulsifier having a nonionic hydrophilic group. Therefore, nonionic anionic emulsifiers include nonionic hydrophilic groups (for example, polyoxyalkylene groups such as polyoxyethylene and polyoxypropylene), anionic emulsifiers, alkylene oxide (ethylene oxide and Emulsifiers having nonionic hydrophilic groups such as polyoxyalkylene groups by the addition of propylene oxide and the like).

  Further, when the reactive emulsifier (A2) is an anionic reactive emulsifier having a radical polymerizable functional group having a form in which a radical polymerizable functional group is introduced into an anionic emulsifier (or corresponding to the form), Examples of the anionic emulsifier include sodium lauryl sulfate, ammonium lauryl sulfate, and sodium dodecylbenzenesulfonate.

  Furthermore, when the reactive emulsifier (A2) is a nonionic reactive emulsifier having a radical polymerizable functional group having a form in which a radical polymerizable functional group is introduced into the nonionic emulsifier (or corresponding to the form). Examples of the nonionic emulsifier include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene fatty acid ester, polyoxyethylene polyoxypropylene block polymer, and the like.

  In the reactive emulsifier (A2), the content ratio of the radical polymerizable functional group is not particularly limited. For example, it is sufficient that one radical polymerizable functional group is contained in one molecule of the reactive emulsifier (A2). In addition, two or more may be included.

  As the reactive emulsifier (A2), for example, as a nonionic anionic reactive emulsifier having a radical polymerizable functional group, the trade name “Adeka Soap SE-10N” (Asahi Denka Kogyo Co., Ltd .; average added mole number of ethylene oxide) 10), trade name “AQUALON HS-20” (Daiichi Kogyo Seiyaku Co., Ltd.); (average added mole number of ethylene oxide 20), trade name “AQUALON HS-10” (Daiichi Kogyo Seiyaku Co., Ltd.); (The average added mole number of ethylene oxide is 10), the trade name “AQUALON HS-05” (Daiichi Kogyo Seiyaku Co., Ltd .; average added mole number of ethylene oxide is 5), and the like are commercially available.

In the present invention, when a radiation-curing / removable acrylic pressure-sensitive adhesive sheet is used as a semiconductor wafer processing pressure-sensitive adhesive sheet, impurity ions in the radiation-curing / removable water-dispersible acrylic pressure-sensitive adhesive composition may cause a problem. Therefore, it is desirable that the impurity ions contained in the radiation-curable re-peeling water-dispersed acrylic pressure-sensitive adhesive composition be reduced or removed. Therefore, as the reactive emulsifier (A2), for example, it is desirable that the concentration of SO ₄ ²⁻ ions is 100 μg / g or less. As the reactive emulsifier (A2), it is desirable to use an ammonium salt type emulsifier. In addition, as a method for reducing or removing impurity ions, for example, an appropriate method such as an ion exchange resin method, a membrane separation method, or an impurity precipitation filtration method using alcohol can be used.

  The proportion of the reactive emulsifier (A2) is about 0.1 to 5 parts by weight, preferably about 0.5 to 3 parts by weight, based on 100 parts by weight of the monomer component (A1). If the compounding amount of the reactive emulsifier (A2) exceeds 5 parts by weight with respect to 100 parts by weight of the monomer component (A1), the element piece is peeled off from the adhesive sheet during the dicing process or in the subsequent process. There is a case. On the other hand, when the proportion of the reactive emulsifier (A2) is less than 0.1 parts by weight with respect to 100 parts by weight of the monomer component (A1), a stable emulsified state may not be maintained.

  An emulsifier having no radical polymerizable functional group can be used in combination with the reactive emulsifier (A2). Examples of such an emulsifier having no radically polymerizable functional group include sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium polyoxyethylene alkyl ether sulfate, polyoxyethylene alkyl phenyl ether ammonium sulfate, polyoxyethylene Anionic emulsifiers and nonionic anionic emulsifiers such as sodium ethylene alkylphenyl ether sulfate and sodium polyoxyethylene alkyl sulfosuccinate; polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene fatty acid ester, polyoxyethylene polyoxypropylene Nonionic emulsifiers such as block polymers are exemplified.

  The preparation method of the acrylic emulsion polymer (A) is not particularly limited as long as it is a preparation method by emulsion polymerization using the monomer component (A1) and the reactive emulsifier (A2). In such emulsion polymerization, a polymerization initiator, a chain transfer agent, or the like can be used.

  Examples of the 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, 2,2'-azobis (N, N'-dimethyleneisobutylamidine) and other azo Polymerization initiators; persulfates such as potassium persulfate and ammonium persulfate; peroxide polymerization initiators such as benzoyl peroxide, t-butyl hydroperoxide and hydrogen peroxide; a combination of peroxide and reducing agent Redox initiators [for example, combinations of peroxides and ascorbic acid (such as combinations of hydrogen peroxide and ascorbic acid) Combinations of peroxides and iron (II) salts (such as combinations of hydrogen peroxide and iron (II) salts), redox polymerization initiators such as combinations of persulfate and sodium hydrogen sulfite, etc.] It is done. The polymerization initiators can be used alone or in combination of two or more.

  The amount of the polymerization initiator used can be appropriately determined according to the type and type of monomer component (A1), and is usually 0.01 to 1 part by weight per 100 parts by weight of monomer component (A1). Preferably, the amount is 0.02 to 0.5 parts by weight.

  The chain transfer agent can be used, for example, for adjusting the molecular weight of the acrylic emulsion polymer (A). The chain transfer agent is not particularly limited, and is a known or conventional chain transfer agent such as lauryl mercaptan, glycidyl mercaptan, mercaptoacetic acid, 2-mercaptoethanol, thioglycolic acid, 2-ethylhexyl thioglycolate, 2,3- Examples thereof include dimethylcapto-1-propanol. A chain transfer agent may be used independently and may use 2 or more types together. The amount of chain transfer agent used is usually about 0.001 to 0.5 parts by weight per 100 parts by weight of the monomer component (A1).

  The acrylic emulsion polymer (A) is obtained by emulsion polymerization using the monomer component (A1) and the reactive emulsifier (A2) and, if necessary, a polymerization initiator or a chain transfer agent. Therefore, the acrylic emulsion polymer (A) is prepared in the form of an emulsion. As the emulsion polymerization method, a known or common emulsion polymerization method can be employed. Specific examples include an emulsion polymerization method using a general batch charging method (batch polymerization method), a monomer dropping method, a monomer emulsion dropping method, and the like. When dropping a monomer or the like, it may be dropped continuously, or may be dropped separately. The polymerization temperature can be appropriately selected according to the type of the polymerization initiator, and can be selected from a range of 5 to 100 ° C., for example.

  The gel fraction of the acrylic emulsion polymer (A) is desirably 30% by weight or less (preferably 25% by weight or less). When the gel fraction of the acrylic emulsion polymer (A) exceeds 30% by weight, the adhesive strength before irradiation is reduced. The gel fraction of the acrylic emulsion polymer (A) can be measured in the same manner as the gel fraction of the radiation curable re-peeling water-dispersible acrylic pressure-sensitive adhesive composition.

[Radically polymerizable polyfunctional monomer for radiation curing (B)]
Radiation-curing radical polymerizable polyfunctional monomer (B) [may be simply referred to as “radical polymerizable polyfunctional monomer (B)”] includes α-ray, β-ray, γ-ray, neutron beam, electron beam, etc. Although it will not specifically limit if it can harden | cure by ionizing radiation of this, or an ultraviolet-ray, It is preferable that a three-dimensional network can be efficiently performed after irradiation. Examples of the radical polymerizable polyfunctional monomer (B) include esterified products of (meth) acrylate and polyhydric alcohol [for example, trimethylolpropane tri (meth) acrylate, tetramethylolmethanetetra (meth) acrylate, pentaerythritol tri (meth) ) Acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol monohydroxypenta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,4-butylene glycol di (meth) acrylate, 1,6-hexanediol di (Meth) acrylate, neopentyl glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, etc.]; Lil oligomers; 2-propenyl - di-3-butenyl cyanurate, tris (2-methacryloxyethyl) cyanurate compounds and isocyanurate compounds such as isocyanurate. A radically polymerizable polyfunctional monomer (B) can be used individually or in combination of 2 or more types.

  The viscosity of the radically polymerizable polyfunctional monomer (B) is not particularly limited, but before the radiation irradiation treatment, the pressure-sensitive adhesive layer of the radiation-curable re-peeling water-dispersible acrylic pressure-sensitive adhesive composition is applied to the silicon mirror wafer. In order to increase the adhesive strength, for example, the viscosity at 25 ° C. (measured with a BH viscometer; rotor: No. 4, rotation speed: 10 rpm) is 5 Pa · sec or more (preferably 10 Pa · sec or more). desirable.

  It is important that the ratio of the radical polymerizable polyfunctional monomer (B) is 20 to 200 parts by weight, preferably 30 to 150 parts by weight, more preferably 100 parts by weight of the acrylic emulsion polymer (A). Is 50 to 120 parts by weight. When the ratio of the radical polymerizable polyfunctional monomer (B) is less than 20 parts by weight with respect to 100 parts by weight of the acrylic emulsion polymer (A), the adhesive strength before the radiation treatment is lowered, and the element is dicing. In some cases, the small pieces may be peeled off. In addition, there is a case where the adhesive strength after the radiation irradiation treatment is not significantly reduced, and the element small pieces cannot be easily peeled off in the pickup process. On the other hand, when the ratio of the radical polymerizable polyfunctional monomer (B) is more than 200 parts by weight with respect to 100 parts by weight of the acrylic emulsion polymer (A), the adhesive strength before the radiation irradiation treatment is lowered and the dicing process is performed. In some cases, the element piece may be peeled off.

  In the case of curing by irradiating ultraviolet rays as radiation, a photoreaction initiator (photosensitizer) is blended in advance in the radiation curable re-peeling water-dispersed acrylic pressure-sensitive adhesive composition. Preferably it is. Examples of the photoreaction initiator include benzoin alkyl ether initiators such as benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, and benzoin isobutyl ether; benzophenone, benzoylbenzoic acid, 3,3′-dimethyl Benzophenone compounds such as -4-methoxybenzophenone, polyvinylbenzophenone, α-hydroxycyclohexyl phenyl ketone; ketal compounds such as benzyldimethyl ketal; thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethyl Thioxanthone, Isopropylthioxanthone, 2,4-Dichlorothioxanthone, 2,4-Diethylthioxanthone, 2,4-Diisopropylthioxanthone In addition to thioxanthone compounds such as dodecylthioxanthone, benzyl, benzoin, acetophenone initiators, α-ketol compounds, aromatic sulfonyl chloride compounds, photoactive oxime compounds, and the like can be mentioned. Moreover, as a photoreaction initiator, 1- [4- (2-hydroxyethyl) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one (for example, manufactured by Ciba Specialty Chemicals) Trade name “Irgacure 2959”, trade name “ESACURE KIP EM” (manufactured by Nippon Sebel Hegner), trade name “ESACURE DP 250” (manufactured by Japan Sebel Hegner), and the like.

  As the photoinitiator, a photoinitiator having good water solubility and water dispersibility can be suitably used from the viewpoint of improving workability. Further, the photoreaction initiator may be added and used in a state dissolved in the radical polymerizable polyfunctional monomer (B).

  Although it does not restrict | limit especially as the usage-amount of a photoinitiator, It can select from the range of about 0.1-10 weight part with respect to 100 weight part of acrylic emulsion polymer (A).

  In addition, a photoreaction accelerator can be used in combination with the photoreaction initiator.

  The radiation curable re-peeling water-dispersed acrylic pressure-sensitive adhesive composition contains an acrylic emulsion polymer (A) and a radically polymerizable polyfunctional monomer (B), and if necessary, other than a crosslinking agent. Additives such as tackifiers, anti-aging agents, fillers, colorants (pigments, dyes, etc.), release modifiers, plasticizers, softeners, surfactants, and the like may be blended. In particular, it is preferable to use a crosslinking agent. By using the crosslinking agent, the gel fraction after heat treatment of the radiation-curable re-peeling water-dispersed acrylic pressure-sensitive adhesive composition can be adjusted. Such a crosslinking agent is not particularly limited. For example, a bifunctional or higher functional epoxy crosslinking agent, an isocyanate crosslinking agent, a carbodiimide crosslinking agent, an oxazoline crosslinking agent, an aziridine crosslinking agent, a melamine resin crosslinking agent, A metal chelate type crosslinking agent, a peroxide type crosslinking agent, etc. are mentioned. A crosslinking agent can be used individually or in combination of 2 or more types.

  Specifically, as the crosslinking agent, N, N, N ′, N′-tetraglycidyl-m-xylenediamine, 1,3-bis (N, N-glycidylaminomethyl) cyclohexane, 1,6-hexanediol Epoxy crosslinking agents such as diglycidyl ether; Isocyanate crosslinking agents such as tolylene diisocyanate (block) (block isocyanate crosslinking agents, etc.); Carbodiimides such as “Carbodilite V-01 (manufactured by Nisseibo Co., Ltd.)” Cross-linking agents; epoxy-based cross-linking agents such as polyethylene glycol diglycidyl ether and polyglycerol polyglycidyl ether; water-dispersed isocyanate cross-linking agents such as trade name “Elastolon BN-69 (Daiichi Kogyo Seiyaku Co., Ltd.)”; Oxazoline-based crosslinking agents such as “Epocross WS-500” (manufactured by Nippon Shokubai Co., Ltd.) Aziridine type cross-linking agent such as trade name “Chemite PZ-33 (manufactured by Nippon Shokubai Co., Ltd.)”; hydrophilic treatment carbodiimide type cross-linking agent such as trade name “Carbodilite V-02 (manufactured by Nisshinbo Co., Ltd.)”; Active methylols such as methylol melamine, active methylol groups such as active alkoxymethyl such as hexamethoxymethyl melamine and cross-linking agents containing active alkoxymethyl groups; trade name “Orgachix AI135 (manufactured by Matsumoto Pharmaceutical Co., Ltd.)” A metal chelate type crosslinking agent etc. are mentioned.

  The amount of the crosslinking agent used is, for example, 0.01 to 10 parts by weight, preferably 0.05 to 5 parts by weight, and more preferably 0.1 to 3 parts by weight with respect to 100 parts by weight of the acrylic emulsion polymer (A). It can be selected from a range of about parts by weight.

  The radiation-curable water-removable acrylic pressure-sensitive adhesive composition for re-peeling is obtained by mixing the acrylic emulsion polymer (A) and the radical polymerizable polyfunctional monomer (B). The method of mixing the acrylic emulsion polymer (A) and the radical polymerizable polyfunctional monomer (B) is not particularly limited, but from the viewpoint of workability, the radical polymerizable polyfunctional monomer (B) is water. A method in which an aqueous dispersion of the radical polymerizable polyfunctional monomer (B) in an emulsion state is added to and mixed with the acrylic emulsion polymer (A) as an emulsion is preferably mixed. When the radically polymerizable polyfunctional monomer (B) is dispersed in water to form an emulsion, an emulsifier or a dispersant (particularly, a polymer dispersant containing a polymer having a weight average molecular weight of 8000 or more) is used. be able to. When a polymer dispersant containing a polymer having a weight average molecular weight of 8000 or more is used as the dispersant, the water-resistant adhesion before radiation curing can be improved. Therefore, when the radiation-curable re-peeling water-dispersed acrylic pressure-sensitive adhesive composition is used as, for example, a pressure-sensitive adhesive that forms a pressure-sensitive adhesive layer in a pressure-sensitive adhesive sheet for processing semiconductor wafers used in the production of semiconductor wafers, When dicing a wafer into element pieces, even if dicing while applying water, peeling of the element pieces can be prevented and the manufacturing efficiency of the semiconductor wafer can be improved.

  The weight average molecular weight of the polymer in the polymer dispersant is not particularly limited as long as it is 8000 or more, but is preferably 10,000 or more, more preferably 15000 or more (particularly 30000 or more). In addition, the upper limit of the weight average molecular weight of the polymer in the polymer dispersant is not particularly limited, and may be, for example, 500,000 or less (preferably 300,000 or less, more preferably 100,000 or less). Examples of the polymer in such a polymer dispersant include a polymer (particularly a copolymer) in which a carboxyl group-containing monomer component such as (meth) acrylic acid is used as a monomer component, and polyvinyl alcohol. It is done. In the polyvinyl alcohol, the degree of saponification may be 50% or more (for example, 50 to 100%, preferably 70 to 99%, more preferably 80 to 95%). The polymer dispersant is usually composed only of the polymer, but may contain various additives as necessary.

  Further, the emulsifier used when the radical polymerizable polyfunctional monomer (B) is dispersed in water to form an emulsion is not particularly limited, but a reactive emulsifier having a radical polymerizable functional group is preferably used. Can be used.

  The amount of the dispersant (particularly a polymer dispersant) or emulsifier used when the radical polymerizable polyfunctional monomer (B) is dispersed in water to form an emulsion is the radical polymerizable polyfunctional monomer (B). The amount is not particularly limited as long as it can be dispersed in water to form an emulsion. As the usage-amount of the said dispersing agent (especially polymer dispersing agent), for example, 0.1-10 weight part (preferably 0.5-5 weight) with respect to 100 weight part of radically polymerizable polyfunctional monomers (B). Part, more preferably 1 to 3 parts by weight). Moreover, as the usage-amount of an emulsifier, for example with respect to 100 weight part of radically polymerizable polyfunctional monomers (B), 0.1-10 weight part (preferably 0.5-5 weight part, More preferably, it is 1-3. Part by weight).

  The pressure-sensitive adhesive layer can be formed by drying and curing the radiation-curable re-peeling water-dispersed acrylic pressure-sensitive adhesive composition by heat treatment. The gel fraction after the heat treatment (and before the radiation irradiation treatment) in the radiation curable re-peeling water-dispersed acrylic pressure-sensitive adhesive composition is not particularly limited, but is 20 to 60% by weight (preferably 30 to 55% by weight). ) Is desirable. When the gel fraction after heat treatment exceeds 60% by weight, the radiation-curable water-removable acrylic pressure-sensitive adhesive composition for re-peeling has low adhesive strength before radiation treatment, and the element pieces are peeled off during the dicing process. May end up. On the other hand, if the gel fraction after heat treatment is less than 20% by weight, the radiation-curable water-removable acrylic pressure-sensitive adhesive composition for re-peeling is not sufficiently lowered in adhesive strength due to radiation irradiation, May contaminate the body.

  In addition, in the radiation curable re-peeling water-dispersed acrylic pressure-sensitive adhesive composition, the gel fraction after the heat treatment (and before the radiation irradiation treatment) is, for example, the radiation curable type after the heat treatment (and before the radiation irradiation treatment). About 0.1 g of a water-dispersed acrylic pressure-sensitive adhesive composition for re-peeling (for example, pressure-sensitive adhesive layer) is sampled and precisely weighed (weight before immersion), and this is placed in room temperature (20 to 20 ml) in about 50 ml of ethyl acetate. After being soaked at about 25 ° C. for 1 week, the solvent (ethyl acetate) insoluble matter is taken out, the solvent insoluble matter is dried at 130 ° C. for about 1 hour, and weighed (weight after soaking and drying) to obtain the gel content. It can be calculated using the rate calculation formula “gel fraction (% by weight) = [(weight after immersion / drying) / (weight before immersion)] × 100”.

  In the measurement of the gel fraction, the heat treatment of the radiation curable re-peeling water-dispersed acrylic pressure-sensitive adhesive composition means a drying treatment or a curing treatment by heating performed when forming the pressure-sensitive adhesive layer. is doing. The heating temperature at this time can be appropriately selected according to the composition of the radiation curable re-peeling water-dispersed acrylic pressure-sensitive adhesive composition.

[Radiation-curing re-peelable acrylic adhesive sheet]
The radiation-curable re-peelable acrylic pressure-sensitive adhesive sheet of the present invention has a pressure-sensitive adhesive layer made of the radiation-curable re-peelable water-dispersed acrylic pressure-sensitive adhesive composition. Specifically, as the radiation curable re-peelable acrylic pressure-sensitive adhesive sheet, for example, a support (base material) and the water-curable re-peelable water-dispersible acrylic pressure-sensitive adhesive composition formed on the support, for example. And a structure having a pressure-sensitive adhesive layer (sometimes referred to as a “radiation-curing re-peelable pressure-sensitive adhesive layer”). In addition, this radiation curing re-peelable acrylic pressure-sensitive adhesive sheet has a configuration that can be re-peeled by radiation irradiation treatment after being attached to an adherend.

  In the radiation-curing / removable acrylic pressure-sensitive adhesive sheet, the thickness of the radiation-curing / removable pressure-sensitive adhesive layer is not particularly limited, and is, for example, about 1 to 100 μm, preferably about 2 to 20 μm.

  As a method for forming the radiation-curing re-peelable pressure-sensitive adhesive layer, a known or conventional forming method can be employed. For example, a radiation-curable re-peeling water-dispersible acrylic pressure-sensitive adhesive composition is applied on a support. Method (coating method), applying a radiation curable re-peeling water-dispersible acrylic pressure-sensitive adhesive composition on a release film to form a radiation curable re-peelable pressure-sensitive adhesive layer, Examples thereof include a method of transferring the agent layer onto the support (transfer method).

  The gel fraction of the radiation curable re-peelable pressure-sensitive adhesive layer before the radiation irradiation treatment is not particularly limited, but as described above, it is desirably 30% by weight or less (preferably 25% by weight or less).

  The radiation-curable re-peelable pressure-sensitive adhesive layer can be formed on a support. Examples of the support include plastic base materials such as plastic films and sheets; metal base materials such as metal foils and metal plates; paper base materials such as paper; and fiber base materials such as cloth, nonwoven fabric, and net. Materials: Rubber-based substrates such as rubber sheets; appropriate thin leaves such as foams such as foam sheets can be used. You may use a support body in combination of 1 type, or 2 or more types. The support is preferably a plastic film or sheet. Examples of plastic film and sheet materials (plastic materials) include α-olefin monomers such as polyethylene (PE), polypropylene (PP), ethylene-propylene copolymer, and ethylene-vinyl acetate copolymer (EVA). Olefin resin as component; Polyester resin such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT); Polyvinyl chloride (PVC); Vinyl acetate resin; Polyphenylene sulfide (PPS); Examples thereof include amide resins such as polyamide (nylon) and wholly aromatic polyamide (aramid); polyimide resins; polyether ether ketone (PEEK). The plastic material may be used alone, or may be used in a mixed state in which two or more kinds are combined. The plastic film or sheet may be in an unstretched state or may be in a stretched state subjected to uniaxial or biaxial stretching treatment.

  It is preferable to use a support that does not inhibit the transmission of radiation such as ultraviolet rays.

  On one side or both sides of the support, appropriate treatment such as physical treatment such as corona treatment or plasma treatment, chemical treatment such as undercoat agent, etc. for the purpose of improving the adhesion with the radiation-curing / removable pressure-sensitive adhesive layer, etc. Surface treatment may be performed.

  The thickness of the support is, for example, about 10 to 300 μm, preferably about 30 to 200 μm.

  The radiation-curing / removable acrylic pressure-sensitive adhesive sheet may be provided with other layers as long as the effects of the present invention are not impaired.

  As the radiation-curable re-peelable acrylic pressure-sensitive adhesive sheet of the present invention, a pressure-sensitive adhesive layer (radiation-curable re-peelable pressure-sensitive adhesive layer) is provided on a support by the radiation-curable re-peelable water-dispersible acrylic pressure-sensitive adhesive composition. In addition, a sheet-like or tape-like form can be used. In order to protect the radiation curable re-peelable pressure-sensitive adhesive layer, a release film may be laminated on the radiation curable re-peelable pressure-sensitive adhesive layer. Such a radiation curable re-peelable acrylic pressure-sensitive adhesive sheet can be a wound body, for example, rolled up in a state of protecting the radiation curable re-peelable pressure-sensitive adhesive layer with a release film (separator). It may be a wound body. When a release film is not used, the back surface of the support is subjected to a back treatment with a release treatment agent such as a silicone release agent or a long-chain alkyl release agent, so that the radiation-cured re-peeling type adhesive on the back treatment surface. In a state where the agent layer is protected, it can be wound into a roll to form a wound body.

  As a release film, for example, a plastic film (for example, a synthetic resin film such as a polyethylene film, a polypropylene film, a polyethylene terephthalate film, etc.) surface-treated with a release treatment agent such as silicone, long chain alkyl, fluorine, molybdenum sulfide, etc. ) Or a substrate having a release treatment layer such as paper; polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, tetrafluoroethylene / hexafluoropropylene copolymer, chlorofluoroethylene / vinylidene fluoride A low-adhesive base material made of a fluorine-based polymer such as a copolymer; a low-adhesive base material made of a nonpolar polymer such as an olefin-based resin (for example, polyethylene or polypropylene) can be used. In addition, a peeling film can be formed by a well-known thru | or usual method. Further, the thickness of the release film is not particularly limited.

  The release film may be subjected to radiation transmission prevention treatment such as ultraviolet transmission prevention treatment. If the release film has been subjected to radiation transmission prevention treatment, the radical polymerizable polyfunctional monomer (B) in the radiation-curing re-peelable pressure-sensitive adhesive layer reacts with radiation existing in a normal space such as environmental ultraviolet rays, It can prevent or suppress that adhesiveness falls.

  In addition, the said peeling film can be provided as needed also for label processing, the smoothness improvement of a radiation hardening re-peeling type adhesive layer, etc.

  In particular, when the radiation-curing / removable acrylic pressure-sensitive adhesive sheet of the present invention is used as a pressure-sensitive adhesive sheet for processing semiconductor wafers, polyester-based films such as polyethylene terephthalate film, polybutylene terephthalate film, and polyethylene naphthalate film are used as a support. Film: It is preferable to use a polyolefin film such as a biaxially stretched polypropylene film or a low density polyethylene film, an ethylene-vinyl acetate copolymer film, and a multilayer film including these films. In particular, when a polyolefin-based film is used as a support, it is possible to form a wound body without using a silicone-based release treatment agent. In this case, silicone contamination may occur on an adherend such as a wafer. This is a particularly preferable form.

  In the present invention, the radiation-curable re-peelable acrylic pressure-sensitive adhesive sheet can exhibit excellent adhesive strength before the radiation irradiation treatment, and can exhibit excellent peelability (re-peelability) after the radiation irradiation treatment. . Although it does not restrict | limit especially as an adhesive force (adhesion force) before the radiation irradiation process of a radiation hardening re-peelable acrylic adhesive sheet, It is important to have high adhesive force, for example, before a radiation irradiation process Adhesive strength of silicon mirror wafer to mirror surface (23 ° C. × 50% RH atmosphere, 180 ° peeling, tensile speed 300 mm / min) is 4.5 N / 20 mm or more (preferably 4.8 N / 20 mm or more). Is desirable.

  Moreover, as the adhesive force after the radiation irradiation treatment of the radiation-curing re-peelable acrylic pressure-sensitive adhesive sheet, it is important to have a low adhesive force, for example, to the mirror surface of the silicon mirror wafer after the radiation irradiation treatment Adhesive strength (23 ° C. × 50% RH atmosphere, 180 ° peeling, tensile speed 300 mm / min) is 0.1 N / 20 mm or less (preferably 0.08 N / 20 mm or less, more preferably 0.05 N / 20 mm or less) It is desirable that

  Thus, the radiation-curing re-peelable acrylic pressure-sensitive adhesive sheet has an adhesive force to the mirror surface of the silicon mirror wafer (23 ° C. × 50% RH atmosphere, 180 ° peel, tensile speed 300 mm / min) of 4.5 N / min. It is 20 mm or more, and the adhesive force (23 ° C. × 50% RH atmosphere, 180 ° peeling, tensile speed 300 mm / min) to the mirror surface of the silicon mirror wafer after radiation irradiation treatment is 0.1 N / 20 mm or less. In addition to exhibiting excellent adhesiveness before radiation irradiation, the adhesiveness can be effectively reduced by irradiation and good peelability can be exhibited. Specifically, for example, when a radiation-curing re-peelable acrylic pressure-sensitive adhesive sheet is used as a pressure-sensitive adhesive sheet for processing semiconductor wafers, the adhesiveness to the element small pieces is good before radiation irradiation, and easy after radiation irradiation. The element piece can be peeled again.

  As described above, the radiation-curable re-peelable acrylic pressure-sensitive adhesive sheet can exhibit excellent adhesive strength before the radiation treatment. The reactive emulsifier (A2) and the radical-polymerizable polyfunctional for radiation curing. This is because the monomer (B) is used in combination.

  The radiation-curing / removable acrylic pressure-sensitive adhesive sheet of the present invention can be suitably used particularly as a pressure-sensitive adhesive sheet for processing semiconductor wafers, but its use is not limited at all. For example, semiconductors, circuits, various printed boards , Surface protection and damage prevention in the manufacture of micro-fabricated parts such as various masks and lead frames [especially electronic parts such as semiconductor wafers (silicon wafers), multilayer substrates, multilayer ceramics, batch sealing modules, etc.] Alternatively, it can be used for removing foreign substances and masking.

[Processing method of adherend]
The method for processing an adherend according to the present invention is a method for processing an adherend using the radiation-curing / removable acrylic pressure-sensitive adhesive sheet. After attaching the adherend and processing the adherend, by subjecting the adherend subjected to the processing treatment to the radiation-curing re-peelable acrylic pressure-sensitive adhesive sheet by radiation irradiation treatment, This is a method for processing an adherend to obtain a treated adherend. In this way, the adherend can be processed while protecting the surface of the adherend and preventing damage by the radiation-curing / removable acrylic pressure-sensitive adhesive sheet. However, processing can be easily performed with excellent accuracy.

  By such a method for processing an adherend, various articles are manufactured according to the type of adherend and the processing method. As an article manufactured by using the method for processing the adherend, for example, when an electronic component such as a semiconductor wafer shown below is used as the adherend, an electronic component (for example, a semiconductor chip) Etc. are manufactured. Therefore, the radiation-curing / removable acrylic pressure-sensitive adhesive sheet of the present invention can be suitably used for grinding or cutting a semiconductor wafer.

  In the processing method, the adherend (workpiece) is not particularly limited, and may be, for example, a fragile work piece. Specifically, as described above, as described above, for example, semiconductors, circuits, various printed boards, various masks, microfabricated parts such as lead frames [in particular, semiconductor wafers (silicon wafers, etc.), multilayer boards, Electronic parts such as multilayer ceramics and batch sealing modules]. The adherend may be used alone or in combination of two or more.

  In addition, the processing of the adherend is not particularly limited, and various processings such as grinding and cutting of a semiconductor wafer (for example, backside polishing processing of a semiconductor wafer, thin grinding processing, dicing processing) , Fine processing, cutting processing, etc.).

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. In the following, “parts” means all parts by weight. Example 3 is described as a reference example.

Example 1
A reaction vessel equipped with a cooling tube, a nitrogen introduction tube, a thermometer, and a stirrer was charged with 50 parts of water and 0.1 part of a trade name “VA-057” (manufactured by Wako Pure Chemical Industries, Ltd.) as a polymerization initiator. The mixture was purged with nitrogen for 1 hour under stirring. Thereafter, the temperature in the container was raised to 60 ° C., water: 50 parts, methyl acrylate: 100 parts as a monomer component, acrylic acid: 2 parts, lauryl mercaptan: 0.1 part as a chain transfer agent, and Emulsions obtained by emulsifying 1 part of an ether sulfate reactive nonionic anionic surfactant (trade name “Adekasoap SE-10N” manufactured by Asahi Denka Kogyo Co., Ltd.) as an emulsifier with an emulsifier. The solution was added dropwise at an inner bath temperature of 60 ° C. over 4 hours, and further aged at 60 ° C. for 3 hours. Thereafter, the mixture was neutralized with a 10% by weight aqueous ammonia solution to prepare an acrylic emulsion polymer having a gel fraction of 10% by weight (sometimes referred to as “acrylic polymer A”).

  Separately, 100 parts of the trade name “KAYARAD DPHA” (manufactured by Nippon Kayaku Co., Ltd.) as a polyfunctional monomer and 3 parts of the trade name “Irgacure 184” (manufactured by Ciba Specialty Chemicals) as a photoinitiator are added. Then, polyvinyl alcohol (weight average molecular weight: 37000, saponification degree: 88%): 2 parts, and water: 50 parts are added as a dispersant and emulsified with an emulsifier to obtain a polyfunctional monomer emulsion solution. (May be referred to as “multifunctional monomer emulsion solution B”).

  Acrylic polymer A: 100 parts (solid content) of 1,3-bis (N, N-glycidylaminomethyl) cyclohexane (trade name “Tetrad C” manufactured by Mitsubishi Gas Chemical Co., Ltd.) 0.2 70 parts (monomer component) of the polyfunctional monomer emulsion solution B was added to prepare a radiation curable re-peeling water-dispersed acrylic pressure-sensitive adhesive (referred to as “acrylic pressure-sensitive adhesive A”).

  Acrylic adhesive A was applied to one side of a polyolefin film (thickness: 70 μm) that had been subjected to corona discharge treatment, and then dried at 80 ° C. for 3 minutes to obtain a thickness (thickness after drying): 10 μm. A silicone film of a polyester film (thickness: 38 μm) with a silicone release treatment applied to one side of the adhesive layer is bonded to a chestnut-treated surface to form a radiation-curing re-peelable acrylic system. An adhesive sheet was prepared. In the radiation-curing / removable acrylic pressure-sensitive adhesive sheet, the gel fraction of the pressure-sensitive adhesive layer by the acrylic pressure-sensitive adhesive A was 45% by weight.

(Example 2)
An acrylic emulsion polymer (“acrylic polymer B”) was used in the same manner as in Example 1 except that methyl acrylate: 70 parts, acrylic acid n-butyl: 30 parts, and acrylic acid: 2 parts were used as monomer components. Was prepared). The acrylic polymer B had a gel fraction of 8% by weight. Further, a radiation-curable re-peeling water-dispersible acrylic pressure-sensitive adhesive (referred to as “acrylic pressure-sensitive adhesive B”) was prepared in the same manner as in Example 1 except that this acrylic polymer B was used. Furthermore, a radiation-curing re-peelable acrylic pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that this acrylic pressure-sensitive adhesive B was used. In the radiation-curing / removable acrylic pressure-sensitive adhesive sheet, the gel fraction of the pressure-sensitive adhesive layer by the acrylic pressure-sensitive adhesive B was 47% by weight.

(Example 3)
Polyvinyl alcohol as a dispersant (weight average molecular weight: 37000, saponification degree: 88%): ether sulfate type surfactant (trade name “Hytenol N-17”, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) instead of 2 parts: 2 A polyfunctional monomer emulsion solution (sometimes referred to as “polyfunctional monomer emulsion solution G”) was prepared in the same manner as in Example 1 except that the parts were used. Also, a radiation curable re-peeling water-dispersible acrylic pressure-sensitive adhesive (referred to as “acrylic pressure-sensitive adhesive G”) was prepared in the same manner as in Example 1 except that this polyfunctional monomer emulsion solution G was used. . Furthermore, a radiation-curing re-peelable acrylic pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that this acrylic pressure-sensitive adhesive G was used. In the radiation-curing re-peelable acrylic pressure-sensitive adhesive sheet, the gel fraction of the pressure-sensitive adhesive layer by the acrylic pressure-sensitive adhesive G was 45% by weight.

(Comparative Example 1)
As an emulsifier, an acrylic emulsion polymer (““ Latermul E118B ”manufactured by Kao Corporation), which is a non-reactive emulsifier, was used in the same manner as in Example 1, except that 1 part was used. Acrylic polymer C ") was prepared. The acrylic polymer C had a gel fraction of 9% by weight. Further, a radiation-curable re-peeling water-dispersible acrylic pressure-sensitive adhesive (referred to as “acrylic pressure-sensitive adhesive C”) was prepared in the same manner as in Example 1 except that this acrylic polymer C was used. Furthermore, a radiation-curing re-peelable acrylic pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that this acrylic pressure-sensitive adhesive C was used. In the radiation-curing / removable acrylic pressure-sensitive adhesive sheet, the gel fraction of the pressure-sensitive adhesive layer by the acrylic pressure-sensitive adhesive C was 43% by weight.

(Comparative Example 2)
As an emulsifier, an acrylic sulfate-type surfactant (trade name “Hytenol N-17”, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), which is a non-reactive emulsifier, was used in the same manner as in Example 1 except that acrylic. An emulsion polymer (referred to as “acrylic polymer D”) was prepared. The acrylic polymer D had a gel fraction of 9% by weight. Further, a radiation-curable re-peeling water-dispersible acrylic pressure-sensitive adhesive (referred to as “acrylic pressure-sensitive adhesive D”) was prepared in the same manner as in Example 1 except that this acrylic polymer D was used. Furthermore, a radiation-curing re-peelable acrylic pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that this acrylic pressure-sensitive adhesive D was used. In the radiation-curing / removable acrylic pressure-sensitive adhesive sheet, the gel fraction of the pressure-sensitive adhesive layer by the acrylic pressure-sensitive adhesive D was 44% by weight.

(Comparative Example 3)
Radiation curable re-peeling in the same manner as in Example 1 except that the addition amount of the polyfunctional monomer emulsion solution B was 10 parts (monomer content) with respect to 100 parts (solid content) of the acrylic polymer A. A water-dispersed acrylic pressure-sensitive adhesive (referred to as “acrylic pressure-sensitive adhesive E”) was prepared. Furthermore, a radiation-curable re-peelable acrylic pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that this acrylic pressure-sensitive adhesive E was used. In the radiation-curing re-peelable acrylic pressure-sensitive adhesive sheet, the gel fraction of the pressure-sensitive adhesive layer by the acrylic pressure-sensitive adhesive E was 60% by weight.

(Comparative Example 4)
Radiation curable re-peeling in the same manner as in Example 1 except that the addition amount of the polyfunctional monomer emulsion solution B was 250 parts (monomer content) with respect to 100 parts (solid content) of the acrylic polymer A: A water-dispersed acrylic pressure-sensitive adhesive (referred to as “acrylic pressure-sensitive adhesive F”) was prepared. Furthermore, a radiation-curable re-peelable acrylic pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that this acrylic pressure-sensitive adhesive F was used. In the radiation-curing re-peelable acrylic pressure-sensitive adhesive sheet, the gel fraction of the pressure-sensitive adhesive layer by the acrylic pressure-sensitive adhesive F was 23% by weight.

(Evaluation)
About the radiation-curing / removable acrylic pressure-sensitive adhesive sheet obtained in each example and each comparative example, the adhesive strength before the radiation treatment, the adhesive strength after the radiation treatment, and the dicing property according to the following measurement methods or evaluation methods. Evaluated. The evaluation results are shown in Table 1.

(Measurement method of adhesive strength before radiation treatment)
The radiation-curing / removable acrylic pressure-sensitive adhesive sheet according to each example and each comparative example was cut into a size of 20 mm in width and 100 mm in length to obtain a silicon mirror wafer (trade name “CZN <100> 2.5-3”). .5 (4 inch) "manufactured by Shin-Etsu Semiconductor Co., Ltd.), with a hand roller reciprocated once in a 23 ° C atmosphere, left to stand at 23 ° C for 30 minutes, and then peeled off the adhesive sheet The required force (adhesive force) was measured under the conditions of 23 ° C. × 50% RH atmosphere, 180 ° peeling and a tensile speed of 300 mm / min.

(Measurement method of adhesive strength after radiation treatment)
The radiation-curing / removable acrylic pressure-sensitive adhesive sheet according to each example and each comparative example was cut into a size of 20 mm in width and 100 mm in length to obtain a silicon mirror wafer (trade name “CZN <100> 2.5-3”). .5 (4 inch) "manufactured by Shin-Etsu Semiconductor Co., Ltd.), a hand roller was reciprocated once in a 23 ° C. atmosphere, left to stand at 23 ° C. for 30 minutes, and then irradiated with ultraviolet rays (irradiation energy: 450 mJ / second). cm ² ) was irradiated for 16 seconds from the adhesive sheet surface side. Thereafter, the force (adhesive force) required to peel the pressure-sensitive adhesive sheet was measured under the conditions of 180 ° peeling and a tensile speed of 300 mm / min in an atmosphere of 23 ° C. × 50% RH.

(Dicing evaluation method)
After mounting a 6-inch wafer having a thickness of 200 μm whose back surface was polished (# 2000 finish) at 23 ° C. on the radiation-curing / removable acrylic pressure-sensitive adhesive sheet according to each example and each comparative example, the following conditions were used. Dicing was performed at 23 ° C. During this dicing, it was observed whether or not the wafer pieces were peeled off from the adhesive sheet. “○” indicates that the wafer pieces were not peeled at all, “△” indicates that 1 to 4 pieces were peeled, and “ “×” was evaluated.
Dicing conditions Dicer: Device name “DFD-651” manufactured by DISCO
Blade: Device name “2050-27HECC” manufactured by DISCO
Blade rotation speed: 40000 rpm
Dicing speed: 80mm / sec
Dicing depth: 30μm
Dicing size: 2mm x 2mm

  As is clear from Table 1, the radiation-curable re-peelable acrylic pressure-sensitive adhesive sheets of Examples 1 and 2 have high adhesive strength before radiation treatment, good dicing properties, and after radiation treatment. The adhesive strength is greatly reduced and can be easily peeled off by radiation irradiation treatment. Moreover, the radiation-curing re-peeling acrylic pressure-sensitive adhesive sheet of Example 3 has the same adhesive strength after the radiation irradiation treatment as that of the radiation-curing re-peeling acrylic pressure-sensitive adhesive sheet of Examples 1 and 2, but before radiation irradiation. Is slightly lower than the radiation-curing / removable acrylic pressure-sensitive adhesive sheets of Examples 1 and 2, and the dicing properties are slightly lower. In the radiation-curing re-peelable acrylic pressure-sensitive adhesive sheets of Examples 1 and 2, when preparing a polyfunctional monomer in an emulsion state, a polymer dispersant with a polymer having a weight average molecular weight of 8000 or more is used as a dispersant. However, in the radiation-curing / removable acrylic pressure-sensitive adhesive sheet of Example 3, since the dispersant using a compound having a low molecular weight (surfactant) is used, the radiation-curing / removing of Example 3 is used. The type acrylic pressure-sensitive adhesive sheet has a lower water resistance than the radiation-curing re-peelable acrylic pressure-sensitive adhesive sheets of Examples 1 and 2, and the dicing property seems to be slightly lowered.

  On the other hand, in Comparative Examples 1 and 2, the adhesive strength after the radiation irradiation treatment is equivalent to that of the example, but since the non-reactive emulsifier is used as the emulsifier, the adhesive strength before the radiation irradiation treatment is low. Dicing property is poor. In Comparative Example 3, since the amount of the polyfunctional monomer component is small, the adhesive strength before the radiation irradiation treatment is low, the dicing property is poor, and the adhesive strength after the radiation irradiation treatment is high. In Comparative Example 4, the adhesive strength after the radiation irradiation treatment is equivalent to that of the example, but the amount of the polyfunctional monomer component is too large, so the adhesive strength before the radiation irradiation treatment is low and the dicing property is poor. .

  Therefore, by using an appropriate amount of radically polymerizable polyfunctional monomer for radiation curing, and by using a reactive emulsifier having a radically polymerizable functional group as an emulsifier when preparing the acrylic emulsion polymer (A) ( At this time, in particular, by using the radically polymerizable polyfunctional monomer for radiation curing as an aqueous dispersion dispersed in water using a polymer dispersant containing a polymer having a weight average molecular weight of 8000 or more), an aqueous system The pressure-sensitive adhesive layer can be coated with the pressure-sensitive adhesive layer, and the adhesive layer with the pressure-sensitive adhesive has excellent high-adhesivity before the radiation treatment, and the element pieces after microfabrication are peeled off from the pressure-sensitive adhesive sheet. In addition, it has excellent low adhesiveness after the radiation irradiation treatment, and can effectively exhibit the property that the element piece can be easily peeled off from the adhesive sheet.

Claims (9)

An acrylic emulsion polymer (A) obtained by emulsion polymerization using a monomer component (A1) mainly composed of (meth) acrylic acid alkyl ester, and a reactive emulsifier (A2) having a radical polymerizable functional group; A polymer dispersant containing a radiation-curable radical polymerizable polyfunctional monomer (B) , wherein the radiation-curable radical polymerizable polyfunctional monomer (B) contains a polymer having a weight average molecular weight of 8000 or more. It is blended as an aqueous dispersion dispersed in water, and the ratio of the radically polymerizable polyfunctional monomer (B) for radiation curing is 20 with respect to 100 parts by weight of the acrylic emulsion polymer (A). A radiation-curable water-dispersible acrylic pressure-sensitive adhesive composition for re-peeling, characterized by being -200 parts by weight. The radiation-curable re-peeling water-dispersible acrylic system according to claim 1, wherein the amount of the polymer dispersant used is 0.1 to 10 parts by weight with respect to 100 parts by weight of the radiation-curable radical polymerizable polyfunctional monomer (B) Adhesive composition.   The radiation-curable water-removable acrylic pressure-sensitive adhesive composition for re-peeling according to claim 1 or 2, wherein the gel fraction after the heat treatment is 20 to 60% by weight.   A radiation-curable re-peelable acrylic pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer made of the radiation-curable re-peelable water-dispersible acrylic pressure-sensitive adhesive composition according to claim 1.   The adhesion force of the silicon mirror wafer to the mirror surface (23 ° C. × 50% RH atmosphere, 180 ° peeling, tensile speed 300 mm / min) is 4.5 N / 20 mm or more, and the mirror of the silicon mirror wafer after the radiation irradiation treatment The radiation-curing re-peelable acrylic pressure-sensitive adhesive sheet according to claim 4, wherein the adhesive strength to the surface (180 ° peeling under a 23 ° C x 50% RH atmosphere, tensile speed 300 mm / min) is 0.1 N / 20 mm or less.   The radiation-curing / removable acrylic pressure-sensitive adhesive sheet according to claim 4, which is a pressure-sensitive adhesive sheet for processing semiconductor wafers.   A method for processing an adherend using the radiation-curable re-peelable acrylic pressure-sensitive adhesive sheet according to claim 4, wherein the adherend is bonded to the radiation-curable re-peelable acrylic pressure-sensitive adhesive sheet, A method for processing an adherend, comprising: subjecting the body to a treatment treatment, and then peeling the adherend subjected to the treatment treatment from the radiation-curing / removable acrylic pressure-sensitive adhesive sheet by a radiation irradiation treatment.   The method for processing an adherend according to claim 7, wherein the adherend is a microfabricated part.   The method for processing an adherend according to claim 7 or 8, wherein the adherend is an electronic component.