JP2015007190A - Resin film and adhesive tape - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin film which can be embrittled by external stimulation without using a layer constitution of a multilayer structure or a highly hazardous additive.SOLUTION: A resin film that can be embrittled by external stimulation without using a layer constitution of a multilayer structure or a highly hazardous additive can be obtained by incorporating a polymer having an alkoxycarbonyloxystyrene structural unit and an acid generator. The alkoxycarbonyloxystyrene structural unit (a) is preferably a structural unit comprising at least one compound selected from ethoxycarbonyloxystyrene, methoxycarbonyloxystyrene, propoxycarbonyloxystyrene, and tert-butoxycarbonyloxystyrene.

Description

  The present invention relates to a resin film.

  Adhesive tape is used for fixing parts in various industrial fields such as office automation equipment, IT / home appliances, and automobiles as a bonding means with excellent workability and high adhesive reliability. In recent years, from the viewpoint of protecting the global environment, there is an increasing demand for recycling and reuse of used products in various industrial fields such as home appliances and automobiles. When recycling and reusing various products, it is necessary to disassemble the fixed parts, but since the adhesive tape is provided in various parts of the product, the work cost can be reduced by a simple removal process. It is requested.

  In response to such a request, a pressure-sensitive adhesive tape having a decomposable pressure-sensitive adhesive layer, for example, a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer to which a foaming agent that foams by heating is added, or a pressure-sensitive adhesive layer whose adhesive strength is reduced by ultraviolet irradiation Various studies have been made on adhesive tapes and the like. However, when dismantling is imparted to the pressure-sensitive adhesive layer, it is often difficult to achieve compatibility with adhesion performance, and adhesion stability may be impaired.

  On the other hand, an attempt to impart disassembly to the base material of the adhesive tape has been studied. As such a disassembling base material, for example, a laminated body is disclosed in which a plastic film is laminated on both surfaces of an adhesive layer, and the adhesive layer / plastic film can be peeled between layers or the adhesive layer can be destroyed. (See Patent Document 1). However, since the laminated body of the said structure consists of a multilayer structure, there existed a problem which material cost and manufacturing cost tend to become high.

Japanese Unexamined Patent Publication No. 7-178862 JP 2003-286464 A

  The problem to be solved by the present invention is to provide a resin film that can be weakened by an external stimulus without using a multilayer structure or a highly dangerous additive.

  Another object of the present invention is to provide an adhesive tape that can be easily disassembled by an external stimulus.

  In the present invention, the above problem can be solved by a resin film containing a polymer having an alkoxycarbonyloxystyrene structural unit and an acid generator.

  Since the resin film of the present invention does not require the use of an additive due to a multilayer structure or external stimulus, the material cost and the manufacturing cost required for the addition process can be reduced. Moreover, since it is not necessary to use a material with high risk, weakening is possible safely. For this reason, the resin film of this invention can implement | achieve the adhesive tape which can be easily disassembled by external stimulus cheaply and with high safety. Furthermore, since the pressure-sensitive adhesive tape does not require the use of a decomposable pressure-sensitive adhesive layer, both the adhesive stability and the demolition property can be suitably achieved.

  As described above, the pressure-sensitive adhesive tape using the resin film of the present invention can realize adhesion stability and disassembly with low cost and high safety, so there is a high demand for cost reduction and adhesion stability. Further, it can be suitably applied to various parts fixing applications in fields where a large amount of products need to be recycled, for example, industrial fields such as OA equipment, IT / home appliances, and automobiles.

  The resin film of the present invention contains a polymer having an alkoxycarbonyloxystyrene structural unit and an acid generator.

[Polymer]
The polymer used in the present invention is a polymer having an alkoxycarbonyloxystyrene structural unit. The alkoxycarbonyloxystyrene structural unit is a structural unit in which a hydrogen atom in an aromatic ring of a styrene structural unit is substituted with an alkoxycarbonyloxy group.

  The alkoxycarbonyloxy group in the alkoxycarbonyloxystyrene structural unit may be any group in which the alkoxycarbonyl group is dissociated by an acid and a hydroxyl group remains in the aromatic ring, and the carbon atom bonded to the oxygen atom of the alkoxycarbonyloxy group is the first. A secondary or tertiary carbon atom is preferred because it is easily dissociated by an acid.

  The alkoxycarbonyloxy group includes an aminoalkoxycarbonyloxy group, a hydroxyalkoxycarbonyloxy group, a carboxyalkoxycarbonyloxy group in which a part of hydrogen atoms are substituted with an amino group, a hydroxyl group, a carboxy group, a halogen, or an aromatic group, It may be a bromoalkoxycarbonyloxy group, a chloroalkoxycarbonyloxy group, a phenylalkoxycarbonyloxy group, a naphthylalkoxycarbonyloxy group, or the like.

  As the alkoxycarbonyloxystyrene monomer giving the alkoxycarbonyloxystyrene structural unit, alkoxycarbonyloxystyrene represented by the following formula (1) can be used.

(In Formula (1), R ₁ is an alkyl group having 1 to 15 carbon atoms, or an alkyl group having 1 to 15 carbon atoms in which a part of hydrogen atoms is substituted with an amino group, a hydroxyl group, a carboxy group, a halogen, or an aromatic group. Represents a group.)

R ₁ in the formula (1) is an alkyl group having 1 to 15 carbon atoms, or _one having 1 to 15 carbon atoms in which a part of hydrogen atoms are substituted with an amino group, a hydroxyl group, a carboxy group, a halogen, or an aromatic group. An alkyl group is represented, and among them, an alkyl group having a secondary or tertiary carbon atom is preferable, and an alkyl group having a tertiary carbon atom having 4 or more carbon atoms is particularly preferable. The alkoxycarbonyloxy group having the alkyl group is preferably easily dissociated by an acid.

  Examples of such alkoxycarbonyloxystyrene monomers include alkoxystyrenes such as ethoxycarbonyloxystyrene, methoxycarbonyloxystyrene, propoxycarbonyloxystyrene, tert-butoxycarbonyloxystyrene, and p- (3-N, N- Aminoalkoxycarbonyloxy such as dimethylaminopropoxy) carbonyloxystyrene, p- (3-N, N-diethylaminopropoxy) carbonyloxystyrene, p- (3-N, N-di-n-propylaminopropoxy) carbonyloxystyrene Styrenes, p- (3-hydroxypropoxy) carbonyloxystyrene, p- (2-hydroxy-2,2-dimethylethyl) carbonyloxystyrene, p- (2-carboxy-2,2 The dimethylethyl) carbonyloxy styrene p-(2-chloro-2,2-dimethylethyl) carbonyloxy styrene ,, p-(2-phenyl-2,2-dimethylethyl) carbonyloxy styrene can be used.

  The proportion of the alkoxycarbonyloxystyrene structural unit in the total number of moles of the structural units constituting the polymer used in the present invention is preferably 5 mol% or more, more preferably 5 to 99 mol%, More preferably, it is -85 mol%.

  The polymer used in the present invention may contain a structural unit other than the alkoxycarbonyloxystyrene structural unit. Examples of the monomer constituting the other structural unit include styrene, p-hydroxystyrene, methyl methacrylate, cyclohexyl methacrylate, 1-adamantyl methacrylate, 2-methyl-2-adamantyl methacrylate, methyl acrylate, and acrylic. Examples thereof include tert-butyl acid, dimethyl fumarate, diethyl fumarate, diisopropyl fumarate, maleimide, N-phenylmaleimide, N-dodecylmaleimide, vinyl acetate, and vinyl chloride.

  When these other structural units are contained, the proportion of the structural units in the total number of moles of the structural units constituting the polymer is preferably 90 mol% or less, more preferably 15 to 80 mol%. .

  When the polymer used in the present invention is a copolymer, it may be a random polymer of the monomer component or a block polymer. A random polymer is preferable because it facilitates securing initial adhesive strength. Moreover, since it becomes easy to obtain suitable dismantling property, it is preferable that it is a block polymer.

  The number average molecular weight of the polymer used in the present invention is preferably 50,000 to 2,000,000. In the case of a self-supporting film, it is preferably about 80,000 to 100,000, and in the case of a tough film, it is more preferably about 100,000 to 1,000,000. It becomes easy to ensure suitable intensity | strength by setting it as the said molecular weight.

  The said number average molecular weight is standard polystyrene conversion by a gel permeation chromatography (GPC). As an example of measurement conditions, HLC-8220GPC (manufactured by Tosoh Corporation) is used, the column is TSKgel GMHXL (manufactured by Tosoh Corporation), the column temperature is 40 ° C., the eluent is tetrahydrofuran, the flow rate is 1.0 mL / min, and standard polystyrene. Can be measured by using TSK standard polystyrene.

  In order to adjust the molecular weight, a chain transfer agent may be used in the polymerization. Examples of the chain transfer agent include known chain transfer agents such as lauryl mercaptan, glycidyl mercaptan, mercaptoacetic acid, 2-mercaptoethanol, thioglycolic acid, 2-ethylhexyl thioglycolate, and 2,3-dimethylcapto-1-propanol. Can be used.

  The polymer can be produced, for example, by subjecting the monomer or a mixture of monomers to a radical polymerization reaction. Specific examples of the method for producing the acrylic polymer include a living radical polymerization method and a conventionally known radical polymerization method using an azo initiator or a peroxide. Among them, the use of the living radical polymerization method does not cause side reactions such as chain transfer reaction and termination reaction in the radical polymerization process, can suppress the generation of low molecular weight components, and can produce an acrylic polymer with a narrow molecular weight distribution. Therefore, it is preferable.

  Examples of the living radical polymerization method include an atom transfer radical polymerization method (ATRP method), a living radical polymerization method using an organic hetero compound containing a high-frequency group 15 or group 16 element as a catalyst (radical weight mediated by an organic hetero compound). Law) (TERP method, etc.), reversible addition-fragmentation chain transfer polymerization reaction method (RAFT method), and the like.

  The atom transfer radical polymerization method (ATRP method) is a method of polymerizing the above acrylic monomer in the presence of, for example, a transition metal complex and an organic halide.

[Acid catalyst, acid generator]
An acid catalyst (Y1) or an acid generator (Y2) is used for the resin film of the present invention. Examples of the acid catalyst (Y1) include aromatic acids such as p-toluenesulfonic acid and benzenesulfonic acid, organic acids such as aliphatic sulfonic acid, inorganic acids such as hydrochloric acid and sulfuric acid, and hydrates thereof. Can be used.

  The acid generator (Y2) used in the present invention is, for example, a photoacid generator that generates an acid capable of initiating cationic polymerization by irradiation with energy rays such as ultraviolet rays, or a thermal acid that generates acid by heating or the like. It is a generator. In particular, the photoacid generator can be suitably disassembled by two external stimuli of light and heat, but easily decomposes and disassembles when stored as a resin film or when an article is fixed. It can be used particularly preferably because it is difficult to maintain stable storage and adhesion.

  Examples of the photoacid generator include N-hydroxynaphthalimide trifluoromethanesulfonate ester, N-hydroxynaphthalimidemethanesulfonate ester, N-hydroxynaphthalimidebenzenesulfonate ester, N-hydroxynaphthalimidetriflate, bis (cyclohexyl). Sulfonyl) diazomethane, bis (tert-butylsulfonyl) diazomethane, bis (p-toluenesulfonyl) diazomethane, triphenylsulfonium trifluoromethanesulfonate, diphenyl-4-methylphenylsulfonium trifluoromethanesulfonate, diphenyl-2,4,6-trimethylphenyl Sulfonium-p-toluenesulfonate, bis (dodecylphenyl) iodonium hexafluoroantimonate, bi (Tert-butylphenyl) iodonium hexafluorophosphate, bis (tert-butylphenyl) iodonium trifluoromethanesulfonate, triphenylsulfonium trifluoromethanesulfonate, biphenyliodonium trifluoromethanesulfonate, phenyl- (3-hydroxy-pentadecylphenyl) iodonium hexafluoro Antimonate, phenyl- (3-hydroxypentadecylphenyl) iodonium hexafluoroantimonate, and the like can be used.

  What is necessary is just to select a suitable thing suitably for these photo-acid generators according to the use to be used. For example, these acid generators may lower the thermal decomposition temperature when mixed with an adhesive. Among them, acid generation such as N-hydroxynaphthalimide trifluoromethanesulfonate and bis (cyclohexylsulfonyl) diazomethane It is preferable to use an agent having a thermal decomposition temperature of about 150 ° C. or more in order to prevent acid from being generated due to the influence of heat during storage and the like, and the disassembly of the resin film from proceeding.

  Among the photoacid generators, a photoacid generator that generates a gas by heating such as bis (cyclohexylsulfonyl) diazomethane is preferable because it can easily achieve a particularly high dismantling property by acid generation by light and gas generation by heating. . A photoacid generator that hardly generates gas even when heated to about 100 ° C., such as N-hydroxynaphthalimide trifluoromethanesulfonate, is preferable because an adhesive layer having high thermal stability can be obtained.

  Furthermore, among photoacid generators, photoacid generators having a light-absorbing structure such as a benzene ring or a naphthalene ring structure in the skeleton can realize suitable disassembly with less light irradiation time and less content. It is preferable because manufacturing costs and dismantling costs can be easily reduced. On the other hand, these photoacid generators that do not have a light-absorbing structure can be preferably used when stability against light irradiation is required.

  Examples of the thermal acid generator include sulfonium salts, benzothiazonium salts, ammonium salts, and phosphonium salts, such as 4-acetoxyphenyldimethylsulfonium hexafluoroarsenate, benzyl-4-hydroxyphenylmethyl. Sulfonium hexafluoroantimonate, 4-acetoxyphenylbenzylmethylsulfonium hexafluoroantimonate, dibenzyl-4-hydroxyphenylsulfonium hexafluoroantimonate, 4-acetoxyphenylbenzylsulfonium hexafluoroantimonate, 3-benzylbenzothiazolium hexafluoro Antimonate or the like can be used.

[Resin film]
The resin film of the present invention contains the polymer and the acid catalyst (Y1) or the acid generator (Y2). In the resin film of the present invention, the acid component by the acid catalyst or the acid generator decomposes the side chain of the copolymer according to the configuration, and the resin film can be suitably weakened by an external stimulus.

  The resin film of the present invention may be formed by a suitable method such as a method of forming a film by dissolving a solution dissolved in various solvents such as chloroform and a method of forming a film by various extrusion methods.

  Various additives may be added to the resin film of the present invention as long as the effects of the present invention are not impaired. As the additive, for example, a plasticizer, a stabilizer, a colorant, a surfactant and the like can be used. Moreover, you may add additional resin for improving the performance of a resin film as needed.

  The thickness of the resin film may be adjusted as appropriate depending on the mode of use, but when used as a base material for adhesive tapes for fixing various parts, a thin tape thickness is often required, so such applications Is preferably 50 to 1200 μm, preferably 50 to 1000 μm, more preferably 100 to 600 μm, and further preferably 150 to 500 μm.

[Adhesive tape]
The resin film of the present invention can be used as an adhesive tape by providing an adhesive layer on at least one surface. Since the resin film layer is preferably weakened by an external stimulus, the adhesive tape can be suitably disassembled after being attached to the adherend or fixing between the adherends.

  As the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape of the present invention, a pressure-sensitive adhesive layer made of a pressure-sensitive adhesive composition used for a normal pressure-sensitive adhesive tape can be used. Examples of the pressure-sensitive adhesive composition include (meth) acrylic pressure-sensitive adhesives, urethane-based pressure-sensitive adhesives, synthetic rubber-based pressure-sensitive adhesives, natural rubber-based pressure-sensitive adhesives, and silicone-based pressure-sensitive adhesives. A (meth) acrylic copolymer containing a copolymer of (meth) acrylate and other monomers as a base polymer, and additives such as tackifiers and crosslinking agents blended as necessary. An adhesive composition can be preferably used.

  Examples of the (meth) acrylate having 1 to 12 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, n Monomers such as -hexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, etc. Species or two or more are used. Among these, (meth) acrylates having 4 to 12 carbon atoms in the alkyl group are preferable, and (meth) acrylates having a linear or branched structure having 4 to 8 carbon atoms are more preferable. In particular, n-butyl acrylate is preferable because it can easily secure adhesion to an adherend and has excellent cohesive strength and resistance to sebum.

  The content of the (meth) acrylate having 1 to 12 carbon atoms in the acrylic copolymer is preferably 80 to 98.5% by mass in the monomer component constituting the acrylic copolymer, and is 90 to 98. More preferably, it is 5 mass%.

  In addition, the acrylic copolymer used in the present invention may be copolymerized with a highly polar vinyl monomer. Examples of the highly polar vinyl monomer include a vinyl monomer having a hydroxyl group, a vinyl monomer having a carboxyl group, and a vinyl having an amide group. A monomer etc. are mentioned, These 1 type (s) or 2 or more types are used.

  Examples of the monomer having a hydroxyl group include hydroxyl groups such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate and the like ( A (meth) acrylate can be used.

  As the vinyl monomer having a carboxyl group, acrylic acid, methacrylic acid, itaconic acid, maleic acid, (meth) acrylic acid dimer, crotonic acid, ethylene oxide-modified succinic acid acrylate, etc. can be used. It is preferable to use it as a polymerization component.

  Examples of the monomer having an amide group include N-vinylpyrrolidone, N-vinylcaprolactam, acryloylmorpholine, acrylamide, and N, N-dimethylacrylamide.

  Examples of other highly polar vinyl monomers include sulfonic acid group-containing monomers such as vinyl acetate, ethylene oxide-modified succinic acid acrylate, and 2-acrylamido-2-methylpropanesulfonic acid.

  The content of the highly polar vinyl monomer is preferably 1.5 to 20% by mass, more preferably 1.5 to 10% by mass, in the monomer component constituting the acrylic copolymer. More preferably, it is 8 mass%. By containing in the said range, it is easy to adjust the cohesive force, holding force, and adhesiveness of an adhesive to a suitable range.

  In addition, when using an isocyanate type crosslinking agent as a crosslinking agent, as a vinyl monomer which has a functional group which reacts with this, a hydroxyl-containing vinyl monomer is preferable, 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate 6-hydroxyhexyl (meth) acrylate is particularly preferred. The content of the hydroxyl group-containing vinyl monomer that reacts with the isocyanate-based crosslinking agent is preferably 0.01 to 1.0% by mass of the monomer component constituting the acrylic copolymer, and is 0.03 to 0.3% by mass. % Is particularly preferred.

  The acrylic copolymer can be obtained by copolymerization by a known polymerization method such as a solution polymerization method, a cage polymerization method, a suspension polymerization method, or an emulsion polymerization method. A combination method or a bulk polymerization method is preferred. Polymerization can be initiated by peroxides such as benzoyl peroxide and lauroyl peroxide, thermal initiation using azo-based thermal polymerization initiators such as azobisisobutylnitrile, acetophenone-based, benzoin ether-based, benzyl A starting method by ultraviolet irradiation using a ketal-based, acylphosphine oxide-based, benzoin-based or benzophenone-based photopolymerization initiator, or a method by electron beam irradiation can be arbitrarily selected.

  As for the molecular weight of the acrylic copolymer, the weight average molecular weight in terms of standard polystyrene measured by gel permeation chromatography (GPC) is from 4 to 3 million, and preferably from 80 to 2.5 million.

  In the acrylic pressure-sensitive adhesive composition used in the present invention, a tackifier resin may be used in order to improve adhesion to the adherend and surface adhesion strength. Tackifying resins include rosin, polymerized rosin, polymerized rosin ester, rosin phenol, stabilized rosin ester, disproportionated rosin ester, hydrogenated rosin ester, terpene, terpene phenol, petroleum resin Examples thereof include (meth) acrylate resins and the like. When used in an emulsion-type pressure-sensitive adhesive composition, it is preferable to use an emulsion-type tackifying resin.

  Of these, disproportionated rosin ester tackifying resins, polymerized rosin ester tackifying resins, rosin phenol tackifying resins, hydrogenated rosin ester tackifying resins, and (meth) acrylate resins are preferred. One or more tackifying resins may be used.

  The blending ratio when using the acrylic copolymer and the tackifying resin is such that the content of the tackifying resin with respect to 100 parts by mass of the acrylic copolymer is preferably 5 to 60 parts by mass, and 8 to 50. It is preferable that it is a mass part. By setting the ratio between the two in this range, it becomes easy to ensure adhesion with the adherend.

  In the acrylic pressure-sensitive adhesive composition, it is preferable to crosslink the pressure-sensitive adhesive in order to increase the cohesive strength of the pressure-sensitive adhesive layer. Examples of such a crosslinking agent include an isocyanate crosslinking agent, an epoxy crosslinking agent, a metal chelate crosslinking agent, and an aziridine crosslinking agent. Among these, a crosslinking agent of a type that is added after the completion of polymerization and causes the crosslinking reaction to proceed is preferable, and an isocyanate-based crosslinking agent and an epoxy-based crosslinking agent that are highly reactive with a (meth) acrylic copolymer are preferable. An isocyanate-based cross-linking agent is more preferable because adhesion to the substrate is improved.

  Examples of the isocyanate-based crosslinking agent include tolylene diisocyanate, naphthylene-1,5-diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, and trimethylolpropane-modified tolylene diisocyanate. Particularly preferred are trifunctional polyisocyanate compounds. Examples of the trifunctional isocyanate compound include tolylene diisocyanate, trimethylolpropane adducts thereof, and triphenylmethane isocyanate.

  As an index of the degree of cross-linking, the value of the gel fraction for measuring the insoluble content after the pressure-sensitive adhesive layer is immersed in toluene for 24 hours is used. The gel fraction is preferably 25 to 70% by mass. More preferably in the range of 30 to 60% by mass, and still more preferably in the range of 30 to 55% by mass, both cohesion and adhesiveness are good.

The gel fraction is measured as follows. On the release sheet, the pressure-sensitive adhesive composition was applied so that the thickness after drying was 50 μm, dried at 100 ° C. for 3 minutes, and aged at 40 ° C. for 2 days. To do. Next, the weight (G1) of the sample before being immersed in toluene is measured in advance, and the toluene-insoluble matter of the sample after being immersed in a toluene solution at 23 ° C. for 24 hours is filtered by a 300-mesh wire mesh. The weight (G2) of the residue after drying at 110 ° C. for 1 hour is measured, and the gel fraction is determined according to the following formula.
Gel fraction (mass%) = (G2 / G1) × 100

  Additives for adhesives such as plasticizers, softeners, antioxidants, flame retardants, fillers such as glass and plastic fibers / balloons / beads, metal powders, metal oxides, metal nitrides Colorants such as pigments and dyes, leveling agents, thickeners, water repellents, antifoaming agents and the like can be optionally added to the pressure-sensitive adhesive composition.

  The thickness of the pressure-sensitive adhesive layer may be appropriately adjusted depending on the mode of use, but when used as a pressure-sensitive adhesive tape for fixing various components, the thickness is preferably 10 to 200 μm, and more preferably 20 to 100 μm.

  As described above, since the resin film of the present invention does not require the use of an additive due to a multilayer structure or external stimulus, the material cost and the manufacturing cost required for the addition process can be reduced. Moreover, since it is not necessary to use a material with high risk, weakening is possible safely. For this reason, the resin film of this invention can implement | achieve the adhesive tape which can be easily disassembled by external stimulus cheaply and with high safety. Furthermore, since the pressure-sensitive adhesive tape does not require the use of a decomposable pressure-sensitive adhesive layer, both the adhesive stability and the demolition property can be suitably achieved. For this reason, the pressure-sensitive adhesive tape is highly demanded for cost reduction and adhesion stability, and in fields where a large amount of product needs to be recycled, such as OA equipment, IT / home appliances, automobiles, etc. It can be suitably applied to various parts fixing applications.

(Preparation Example 1)
In a reaction vessel equipped with a stirrer, reflux condenser, thermometer, dropping funnel and nitrogen gas inlet, 97.97 parts by mass of n-butyl acrylate, 2.0 parts by mass of acrylic acid, 0.03 mass of 4-hydroxybutyl acrylate Part, 0.1 part by mass of 2,2′-azobisisobutyronitrile as a polymerization initiator was dissolved in a solvent consisting of 100 parts by mass of ethyl acetate, polymerized at 70 ° C. for 12 hours, and the weight average molecular weight was A 2 million (polystyrene equivalent) acrylic copolymer was obtained. Next, ethyl acetate was added to 100 parts by mass of the acrylic copolymer and mixed uniformly to obtain a pressure-sensitive adhesive composition (A) having a nonvolatile content of 40%. 1.3 parts by mass of “Coronate L-45” (isocyanate-based crosslinking agent, solid content 45%) manufactured by Nippon Polyurethane Co., Ltd. was added to 100 parts by mass of the pressure-sensitive adhesive composition (A) prepared above, and 15 minutes. After stirring, coating was performed on the peel-treated surface of a 75 μm-thick PET film that had been peel-treated so that the thickness after drying was 25 μm, and dried at 80 ° C. for 3 minutes to prepare an adhesive layer (A). The gel fraction of the pressure-sensitive adhesive layer was 42.5% by mass.

(Production Example 1)
A mixed solution of 1.6 mg of 2,2′-azobisisobutyronitrile and 2.20 g of BSt was put into a test tube, and after freezing, degassing and melting cycles were repeated three times to remove dissolved oxygen, sealing was performed. did. After reacting for 24 hours in a 60 ° C. water bath, the polymerization was terminated by cooling to −78 ° C., and the polymerization solution was diluted with 2 mL of chloroform and precipitated in 200 mL of methanol. The precipitate was suction filtered and dried at room temperature under reduced pressure for 12 hours to obtain a polymer (1) as a white powder polymer. The polymerization yield calculated by the gravimetric method was 99.7%. From the GPC analysis, it was Mn = 1,046,000, Mw = 1,883,000, PD = 1.8. The glass transition temperature was 122 ° C. from DSC measurement.

(Production Example 2)
A mixed solution of 4.1 mg of 2,2′-azobisisobutyronitrile, 2.75 g of BSt, and 1.30 g of styrene (St) is put into a test tube, and a cycle of freezing, degassing, and melting is performed to remove dissolved oxygen. After repeating 3 times, it was sealed. After reacting for 24 hours in a 60 ° C. water bath, the polymerization was terminated by cooling to −78 ° C., and the polymerization solution was diluted with 2 mL of chloroform and precipitated in 200 mL of methanol. The precipitate was suction filtered and dried at room temperature under reduced pressure for 12 hours to obtain a polymer (2) as a white powder polymer. The polymerization yield calculated by the gravimetric method was 42.3%.
The obtained polymer (2) was Mn = 21,000, Mw = 403,000, PD = 1.90 from GPC analysis. The molar ratio of the constituent components in the copolymer was BSt / St = 63/37.

Example 1
The polymer (1) obtained in the above Production Example 1 is dissolved in chloroform to prepare a 5 wt% solution. After pouring the solution into a mold, the solution is naturally dried at room temperature for 12 hours and a resin film having a thickness of 60 μm. (1) was obtained. The pressure-sensitive adhesive layer (A) prepared in Preparation Example 1 was bonded to one side of the obtained resin film (1), and then laminated with a roll at 23 ° C. underline pressure of 5 kg / cm. Thereafter, aging was performed at 40 ° C. for 48 hours to obtain an adhesive tape.

(Example 2)
The polymer (2) obtained in Production Example 2 above is dissolved in chloroform to prepare a 5 wt% solution, the solution is poured into a mold, and then naturally dried at room temperature for 12 hours, and a resin film having a thickness of 60 μm (2) was obtained. The pressure-sensitive adhesive layer (A) prepared in Preparation Example 1 was bonded to one side of the obtained resin film (2), and then laminated with a roll at 23 ° C. and a linear pressure of 5 kg / cm. Then, it aged at 40 degreeC for 48 hours, and obtained the double-sided adhesive tape.

(Comparative Example 1)
A commercially available styrene polymer (manufactured by Wako Pure Chemical Industries, Mn = 91,000) was dissolved in chloroform to prepare a 10 wt% solution. After pouring the solution into a mold, it was naturally dried at room temperature for 12 hours to obtain a thickness. A 50 μm resin film (H1) was obtained. The pressure-sensitive adhesive layer (A) prepared in Preparation Example 1 was bonded to one side of the obtained resin film (H1) and then laminated with a roll at 23 ° C. and a linear pressure of 5 kg / cm. Then, it aged at 40 degreeC for 48 hours, and obtained the double-sided adhesive tape.

  The following evaluation was performed about the adhesive tape obtained in the said Example and comparative example.

[Heating test]
The PET film was peeled from the adhesive tapes obtained in the above Examples and Comparative Examples, and the non-adhesive surface was placed on an aluminum plate previously heated to 150 ° C. and heated in a heating furnace at 150 ° C. for 15 minutes. The adhesive tape after heating was taken out from the heating furnace, cooled to room temperature, and then both ends of the adhesive tape were pulled by hand. The pressure-sensitive adhesive tapes of Examples 1 and 2 were weakened by heating and easily broken. On the other hand, the pressure-sensitive adhesive tape of Comparative Example 1 was not weakened and was not broken after being pulled.

Claims (4)

  A resin film comprising a polymer having an alkoxycarbonyloxystyrene structural unit and an acid generator.   The resin according to claim 1, wherein the alkoxycarbonyloxystyrene structural unit (a) is a structural unit consisting of at least one selected from ethoxycarbonyloxystyrene, methoxycarbonyloxystyrene, propoxycarbonyloxystyrene, and tert-butoxycarbonyloxystyrene. the film.   The resin film according to claim 1 or 2, wherein the proportion of the alkoxycarbonyloxystyrene structural unit in the total number of moles of the structural units constituting the copolymer (X) is 5 mol% or more.   An adhesive tape comprising an adhesive layer on at least one surface of the resin film according to claim 1.