JPWO2015151223A1 - Double-sided pressure-sensitive adhesive sheet and method for producing double-sided pressure-sensitive adhesive sheet - Google Patents

Abstract

Adhesive provided with the base material 20, the 1st adhesive layer 21 laminated | stacked on the one surface side of the base material 20, and the 2nd adhesive layer 22 laminated | stacked on the other surface side of the base material 1. The laminate, the first release sheet 31 laminated on the surface opposite to the substrate 20 in the first pressure-sensitive adhesive layer 21, and the surface opposite to the substrate 20 in the second pressure-sensitive adhesive layer 21 A double-sided pressure-sensitive adhesive sheet 1 having a second release sheet 32 laminated on the substrate, the substrate 20 has a thickness of 1 to 5 μm, and the first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 22 Each of the thicknesses is 1 to 5 μm, the peel force of the first release sheet 31 and the second release sheet 32 is 10 to 30 mN / 25 mm, and the peel force of the first release sheet 31 and the second release sheet The double-sided pressure-sensitive adhesive sheet 1 having a difference from the peel strength of 32 of 5 mN / 25 mm or less.

Description

  The present invention relates to a double-sided pressure-sensitive adhesive sheet and a method for producing a double-sided pressure-sensitive adhesive sheet.

  The double-sided pressure-sensitive adhesive sheet generally has a structure in which a laminate (adhesive laminate) in which a base material (core material) is interposed between two pressure-sensitive adhesive layers is sandwiched between two release sheets. . In such a double-sided PSA sheet, one of the two release sheets is a light release release sheet having a low release force, and the other is a heavy release release sheet having a high release force (see Patent Document 1).

  In order to use the double-sided pressure-sensitive adhesive sheet, first, the light release type release sheet is peeled off, the exposed pressure-sensitive adhesive layer is attached to the adherend, and then the heavy release type release sheet is peeled off. Thereby, when peeling one release sheet | seat, it can prevent that what is called a float which the adhesion laminated body peels from the other release sheet | seat generate | occur | produces.

  In recent years, portable electronic devices such as smartphones and tablet terminals have been reduced in size and thickness. In manufacturing a portable electronic device, a double-sided pressure-sensitive adhesive sheet is sometimes used to laminate and bond each member, and a thin double-sided pressure-sensitive adhesive sheet having a pressure-sensitive adhesive laminate is desired with the above-mentioned thinning. However, if the pressure-sensitive adhesive laminate of the double-sided pressure-sensitive adhesive sheet is thin, there is a problem that the above-mentioned floating is likely to occur.

  By the way, in the double-sided pressure-sensitive adhesive sheet, the release sheet may be replaced depending on the purpose of use. For example, as one release sheet of the double-sided pressure-sensitive adhesive sheet, a release sheet subjected to a back cracking process (cut or half cut) for enabling split release may be used. When the pressure-sensitive adhesive layer of the double-sided PSA sheet is thick, it can be back-cut by half-cutting while the release sheet is laminated on the double-sided PSA sheet. Since there exists a possibility of cutting a laminated body, it is necessary to replace a normal peeling sheet with the peeling sheet which gave the back crack process previously.

JP 2007-169327 A

  By the way, the double-sided pressure-sensitive adhesive sheet usually protects one surface with a release sheet having a high peel strength and the other surface with a release sheet having a low peel strength. And when replacing with a release sheet that has been subjected to the back cracking process as described above, the release sheet on the side having the lower peeling force is peeled off and the release sheet that has been subjected to the back cracking process is laminated on the exposed adhesive surface. . In the double-sided pressure-sensitive adhesive sheet having a release sheet that has been subjected to a back crack process on one surface, the release sheet on the side that has not been subjected to the back crack process is first peeled off and applied to the adherend. Usage may be required.

  However, as described above, the release sheet on the side not subjected to the back cracking process is already a release sheet having a high release force. For this reason, if the release sheet with the back cracking process has a lower peeling force, it can be peeled only from the side of the release sheet with the back cracking process. Floating or peeling occurs at the interface between the release sheet subjected to cracking and the double-sided pressure-sensitive adhesive sheet. That is, in order to correspond to the above-described use mode, in the double-sided pressure-sensitive adhesive sheet, the release sheet subjected to the back cracking process needs to have a higher peeling force than the release sheet on the side not subjected to the back cracking process. There is.

  As described above, in general, the replacement of the release sheet in the double-sided pressure-sensitive adhesive sheet can be applied only to a release sheet having a higher peeling force than the laminated release sheets. For this reason, there is a limit to the release sheet that can be replaced.

  The present invention has been made in view of such circumstances, and is a double-sided pressure-sensitive adhesive sheet that has a thin adhesive laminate, is unlikely to float when the release sheet is peeled off, and has a degree of freedom in reattaching the release sheet. And it aims at providing the manufacturing method of the double-sided adhesive sheet.

  In order to achieve the above object, first, the present invention is laminated on a base material, a first pressure-sensitive adhesive layer laminated on one surface side of the base material, and the other surface side of the base material. A pressure-sensitive adhesive laminate including the second pressure-sensitive adhesive layer, a first release sheet laminated on the surface of the first pressure-sensitive adhesive layer opposite to the base, and the second pressure-sensitive adhesive. A double-sided pressure-sensitive adhesive sheet comprising a second release sheet laminated on a surface opposite to the base material in the layer, wherein the base material has a thickness of 1 to 5 μm, and the first pressure-sensitive adhesive layer And the thickness of each of the second pressure-sensitive adhesive layers is 1 to 5 μm, and the peeling force of the first release sheet and the second release sheet is 10 to 30 mN / 25 mm, The difference between the peeling force and the peeling force of the second release sheet is 5 mN / 25 mm or less. A landing sheet is provided (Invention 1). In this specification, “sheet” includes the concept of a tape.

  According to the above invention (Invention 1), the base material, the first pressure-sensitive adhesive layer, the second pressure-sensitive adhesive layer, the first release sheet, and the second release sheet are defined as described above. The pressure-sensitive adhesive laminate can be thinned. In addition, even if the pressure-sensitive adhesive laminate is thin, when the first release sheet is peeled from the pressure-sensitive adhesive laminate, a floating that causes the pressure-sensitive adhesive laminate to be peeled off from the second release sheet may occur. When the is peeled from the pressure-sensitive adhesive laminate, it is also possible to prevent the floating that the pressure-sensitive adhesive laminate is peeled off from the first release sheet.

  In addition, when the first release sheet and / or the second release sheet is replaced with another release sheet due to the low release force of the first release sheet and the second release sheet as described above, The release force of the other release sheet may be at least higher than the release force of the first release sheet or the second release sheet, and may be suppressed lower than usual. Therefore, there is a degree of freedom in the replacement of the release sheet, and it can be replaced with various release sheets. Moreover, also when it replaces repeatedly, it can suppress that the peeling force of a peeling sheet becomes high too much, and can maintain the peelability of a peeling sheet favorably. Furthermore, since the difference in peel force is small as described above, there is no problem in workability regardless of which of the first release sheet and the second release sheet is removed first. There is no advantage.

  In the said invention (invention 1), it is preferable that a said 1st peeling sheet and a said 2nd peeling sheet consist of the same material (invention 2).

  In the said invention (invention 1 and 2), it is preferable that a said 1st adhesive layer and a said 2nd adhesive layer consist of the same adhesives (invention 3).

  In the said invention (invention 1-3), it is preferable that the adhesive which forms a said 1st adhesive layer and a said 2nd adhesive layer is an acrylic adhesive (invention 4).

  In the said invention (invention 1-4), it is preferable that the adhesive which forms a said 1st adhesive layer and a said 2nd adhesive layer contains a tackifier (invention 5).

  In the said invention (invention 5), it is preferable that the said adhesive contains polymeric rosin ester and aromatic petroleum resin as said tackifier (invention 6).

  2ndly this invention is a method of manufacturing the said double-sided adhesive sheet (invention 1-6), Comprising: The process of forming a 1st adhesive layer in the peeling surface of a said 1st peeling sheet, The said 1st And laminating the first pressure-sensitive adhesive layer formed on the release surface of the release sheet on one surface side of the substrate, and forming a second pressure-sensitive adhesive layer on the release surface of the second release sheet And a step of laminating the second pressure-sensitive adhesive layer formed on the release surface of the second release sheet on the other surface side of the substrate. Provided (Invention 7)

  The double-sided pressure-sensitive adhesive sheet of the present invention has a thin pressure-sensitive adhesive laminate, is less likely to float when any release sheet is peeled off, and has a degree of freedom in re-attaching the release sheet. Various release sheets can be attached. Moreover, according to the manufacturing method of the double-sided adhesive sheet of this invention, the above double-sided adhesive sheets can be manufactured easily.

1 is a cross-sectional view of a double-sided pressure-sensitive adhesive sheet according to the present embodiment.

Hereinafter, embodiments of the present invention will be described.
[Double-sided adhesive sheet]
FIG. 1 shows a cross-sectional view of a double-sided PSA sheet 1 according to this embodiment.
As shown in FIG. 1, the double-sided pressure-sensitive adhesive sheet 1 according to an embodiment of the present invention includes a base material 20 and a first pressure-sensitive adhesive layer 21 provided on one surface (upper side in FIG. 1) of the base material 20. And the second pressure-sensitive adhesive layer 22 provided on the other surface (lower side in FIG. 1) of the base material 20 and the surface of the first pressure-sensitive adhesive layer 21 opposite to the base material 20 (in FIG. 1). From the first release sheet 31 provided on the upper side) and the second release sheet 32 provided on the surface opposite to the substrate 20 of the second adhesive layer 22 (lower side in FIG. 1). Composed. In addition, the laminated body of the 1st adhesive layer 21, the base material 20, and the 2nd adhesive layer 22 is called the adhesive laminated body 2. FIG.

  The thickness of the base material 20 in the double-sided pressure-sensitive adhesive sheet 1 according to this embodiment is 1 to 5 μm, and the thicknesses of the first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 22 are 1 to 5 μm, respectively. When the thickness of each layer is in the above range, the pressure-sensitive adhesive laminate 2 can be thinned, the interval between two adherends bonded by the pressure-sensitive adhesive laminate 2 can be narrowed, and the resulting product is thin. Can contribute.

  Moreover, the peeling force of the 1st peeling sheet 31 and the 2nd peeling sheet 32 in the double-sided adhesive sheet 1 which concerns on this embodiment is 10-30 mN / 25mm, respectively, It is preferable that it is 15-30 mN / 25mm, In particular, it is preferably 20 to 30 mN / 25 mm. As described above, when both the peeling force of the first release sheet 31 and the second release sheet 32 are as low as 30 mN / 25 mm or less, when the release sheet 31 (or 32) is peeled, the other side is peeled off. It is possible to effectively prevent floating and peeling at the interface between the sheet 32 (or 31) and the pressure-sensitive adhesive layer. Further, when the first release sheet 31 and / or the second release sheet 32 is replaced with another release sheet, the release force of the other release sheet is at least the first release sheet 31 or the second release sheet. What is necessary is just to make it higher than the peeling force of the sheet | seat 32, and it can also be restrained lower than usual. Therefore, there is a degree of freedom in the replacement of the release sheet, and it can be replaced with various release sheets. Moreover, also when it replaces repeatedly, it can suppress that the peeling force of a peeling sheet becomes high too much, and can maintain the peelability of a peeling sheet favorably.

  In addition, the 1st peeling sheet 31 and the 2nd peeling sheet 32 are in process, conveyance, etc. by the peeling force of the 1st peeling sheet 31 and the 2nd peeling sheet 32 being 10 mN / 25mm or more. The first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 22 can be in close contact with each other to protect them.

  The difference (absolute value) between the peel force of the first release sheet 31 and the peel force of the second release sheet 32 in the double-sided pressure-sensitive adhesive sheet 1 according to this embodiment is 5 mN / 25 mm or less, and is 4 mN / 25 mm or less. In particular, it is preferably 2 mN / 25 mm or less. As described above, the difference in peel force between the first release sheet 31 and the second release sheet 32 is as small as 5 mN / 25 mm or less. When the release sheet 31 is peeled from the adhesive laminate 2, the adhesive laminate 2 may be lifted off from the second release sheet 32, or the second release sheet 32 may be peeled off from the adhesive laminate 2. In such a case, it is possible to prevent the floating of the pressure-sensitive adhesive laminate 2 from the first release sheet 31.

  Further, since the difference in peeling force is small as described above, there is no problem in workability regardless of which of the first peeling sheet 31 and the second peeling sheet 32 is peeled first, and therefore the peeling order is distinguished. There is an advantage that it is not necessary. In addition, the difference of the said peeling force is an absolute value, and either the peeling force of the 1st peeling sheet 31 and the peeling force of the 2nd peeling sheet 32 may be large or small. In addition, the measuring method of the said peeling force is as showing to the test example mentioned later.

(1) Base Material The base material 20 of the double-sided pressure-sensitive adhesive sheet 1 according to the present embodiment supports the first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 22 and gives a predetermined rigidity to the pressure-sensitive adhesive laminate 2. Have That is, when the double-sided pressure-sensitive adhesive sheet 1 has the base material 20, the rigidity of the pressure-sensitive adhesive laminate 2 as a whole is increased, and when this occurs, one of the release sheets is peeled off at the interface between the other release sheet and the pressure-sensitive adhesive layer. It is possible to effectively prevent floating and peeling.

  As described above, the thickness of the base material 20 is 1 to 5 μm, preferably 1 to 4 μm, and particularly preferably 1 to 2 μm. When the thickness of the base material 20 exceeds 5 μm, the thinness required for the pressure-sensitive adhesive laminate 2 cannot be obtained. Moreover, the function as a base material of the adhesion laminated body 2 cannot fully be performed as the thickness of the base material 20 is less than 1 micrometer.

  The substrate 20 is not particularly limited as long as it satisfies the above thickness and can laminate the first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 22.

  Examples of the base material 20 include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyolefin films such as polyethylene film and polypropylene film, cellulose films such as triacetyl cellulose, polyvinyl chloride films, and polyvinylidene chloride. Film, polyvinyl alcohol film, ethylene-vinyl acetate copolymer film, polyurethane film, polystyrene film, polycarbonate film, polyimide film, polyetheretherketone film, polyetherimide film, polyethersulfone film, polyphenylsulfone film, Polyphenylene sulfide film, aramid film, nylon film, active film Aluminum, metal foils such as copper; nonwoven; Le resin film, norbornene resin film, a plastic film such as a cycloolefin resin film which the or mainly of these two or more laminates or the like. Note that “mainly” means that a desired layer thinner than those may be provided.

  Among the above, a plastic film that can be easily thinned and has high smoothness is preferable, and among them, a polyolefin film and a polyester excellent in mechanical strength and economy are preferable, and a polyethylene terephthalate film is particularly preferable.

  In the case of a plastic film, for the purpose of improving the adhesion between the first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 22 provided on the surface thereof, a surface treatment by an oxidation method, a roughening method or the like, or a primer, if desired. Processing can be performed. Examples of the oxidation method include corona discharge treatment, plasma discharge treatment, chromium oxidation treatment (wet), flame treatment, hot air treatment, ozone, ultraviolet irradiation treatment, and the like. Examples include a thermal spraying method. These surface treatment methods are appropriately selected according to the type of the resin film, but generally, a corona discharge treatment method is preferably used from the viewpoints of effects and operability.

(2) First pressure-sensitive adhesive layer / second pressure-sensitive adhesive layer The thicknesses of the first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 22 in the double-sided pressure-sensitive adhesive sheet 1 according to this embodiment are as described above. It is 1-5 micrometers, it is preferable that it is 1-4 micrometers, and it is especially preferable that it is 1.5-2.5 micrometers. When the thickness of the 1st adhesive layer 21 or the 2nd adhesive layer 22 exceeds 5 micrometers, the thinness required about the adhesion laminated body 2 is not obtained. Moreover, when the thickness of the 1st adhesive layer 21 or the 2nd adhesive layer 22 is less than 1 micrometer, adhesive force will become low too much and the function as an adhesive cannot be exhibited stably.

  The pressure-sensitive adhesive forming the first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 22 is not particularly limited as long as it exhibits a desired pressure-sensitive adhesive force with the above thickness. Such an adhesive may be, for example, an acrylic adhesive, a silicone adhesive, a polyester adhesive, a polyurethane adhesive, a rubber adhesive, or the like. The pressure-sensitive adhesive may be any of an emulsion type, a solvent type, or a solventless type, and may be a crosslinked type or a non-crosslinked type. Among the above, an acrylic pressure-sensitive adhesive excellent in adhesiveness and handling property in a thin film is preferable.

  As the acrylic pressure-sensitive adhesive, those containing a (meth) acrylic acid ester polymer (A) are preferable, and the (meth) acrylic acid ester polymer (A) is further crosslinked by a crosslinking agent (B). It is preferable to contain. In this specification, (meth) acrylic acid ester means both acrylic acid ester and methacrylic acid ester. The same applies to other similar terms. Further, the “polymer” includes the concept of “copolymer”.

  The (meth) acrylic acid ester polymer (A) preferably contains a (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group as a monomer constituting the polymer. Thereby, the obtained adhesive can express preferable adhesiveness. The (meth) acrylic acid ester polymer (A) is a monomer having a functional group that reacts with the alkyl group (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms and the crosslinking agent (B) (reactivity). Particularly preferred is a copolymer of a functional group-containing monomer) and other monomers used as desired.

  Examples of the (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and (meth) acrylic acid n-. Butyl, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, n-decyl (meth) acrylate, (meth) acrylic acid Examples include n-dodecyl, myristyl (meth) acrylate, palmityl (meth) acrylate, stearyl (meth) acrylate, and the like. Among these, from the viewpoint of further improving the adhesiveness, (meth) acrylic acid esters having 1 to 8 carbon atoms in the alkyl group are preferable, and n-butyl (meth) acrylate is particularly preferable. In addition, these may be used independently and may be used in combination of 2 or more type.

  The (meth) acrylic acid ester polymer (A) contains 60 to 100% by mass of a (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms as the monomer unit constituting the polymer. The content is preferably 70 to 98% by mass, and more preferably 80 to 96% by mass.

  As the reactive functional group-containing monomer, a monomer having a hydroxyl group in the molecule (hydroxyl group-containing monomer), a monomer having a carboxyl group in the molecule (carboxyl group-containing monomer), a monomer having an amino group in the molecule (amino group-containing) Monomer) and the like. These may be used alone or in combination of two or more.

  Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, (meth And (meth) acrylic acid hydroxyalkyl esters such as 3-hydroxybutyl acrylate and 4-hydroxybutyl (meth) acrylate. Among them, 2-hydroxyethyl (meth) acrylate is preferred from the viewpoint of the reactivity of the hydroxyl group in the resulting (meth) acrylic acid ester polymer (A) with the crosslinking agent (B) and the copolymerizability with other monomers. Is preferred. These may be used alone or in combination of two or more.

  Examples of the carboxyl group-containing monomer include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. Among these, acrylic acid is preferable from the viewpoint of the reactivity of the resulting (meth) acrylic acid ester polymer (A) with the crosslinking agent (B) of the carboxyl group and the copolymerizability with other monomers. These may be used alone or in combination of two or more.

  Examples of the amino group-containing monomer include aminoethyl (meth) acrylate, n-butylaminoethyl (meth) acrylate, and the like. These may be used alone or in combination of two or more.

  The (meth) acrylic acid ester polymer (A) preferably contains 0 to 25% by mass of a reactive functional group-containing monomer as the monomer unit constituting the polymer, particularly 0.1 to 10% by mass. It is preferable to contain 0.3 to 5% by mass.

  Examples of the other monomer include aliphatic rings such as (meth) acrylic acid alkoxyalkyl esters such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate, and cyclohexyl (meth) acrylate (meth) Non-crosslinkable acrylamide such as acrylic ester, acrylamide, methacrylamide, etc. Non-crosslinkable tertiary such as N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate Examples thereof include (meth) acrylic acid ester having an amino group, vinyl acetate, and styrene. By using these monomers, particularly vinyl acetate, the glass transition temperature (Tg) of the resulting pressure-sensitive adhesive can be adjusted. These may be used alone or in combination of two or more.

  When the (meth) acrylic acid ester polymer (A) contains vinyl acetate as a monomer unit constituting the polymer, it preferably contains 0 to 10% by mass of vinyl acetate, particularly 0.1 to 8% by mass. %, Preferably 1 to 5% by mass.

  The polymerization mode of the (meth) acrylic acid ester polymer (A) may be a random copolymer or a block copolymer.

  The weight average molecular weight of the (meth) acrylic acid ester polymer (A) is preferably 200,000 to 3,000,000, particularly preferably 400,000 to 2,000,000, and more preferably 600,000 to 1,200,000. preferable. In addition, the weight average molecular weight in this specification is the value of polystyrene conversion measured by the gel permeation chromatography (GPC) method.

  In addition, in an acrylic adhesive, (meth) acrylic acid ester polymer (A) may be used individually by 1 type, and may be used in combination of 2 or more type.

  The crosslinking agent (B) may be any one that reacts with the reactive functional group of the (meth) acrylic acid ester polymer (A). For example, an isocyanate crosslinking agent, an epoxy crosslinking agent, and an amine crosslinking agent. , Melamine crosslinking agent, aziridine crosslinking agent, hydrazine crosslinking agent, aldehyde crosslinking agent, oxazoline crosslinking agent, metal alkoxide crosslinking agent, metal chelate crosslinking agent, metal salt crosslinking agent, ammonium salt crosslinking agent, etc. Is mentioned. Among these, when the reactive functional group of the (meth) acrylic acid ester polymer (A) is a hydroxyl group, it is preferable to use an isocyanate-based crosslinking agent that is excellent in reactivity with the hydroxyl group, and (meth) acrylic acid When the reactive functional group which the ester polymer (A) has is a carboxyl group, it is preferable to use an epoxy-based crosslinking agent having excellent reactivity with the carboxyl group. In addition, a crosslinking agent (B) can be used individually by 1 type or in combination of 2 or more types.

  The isocyanate-based crosslinking agent contains at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate, and the like. , And their biuret bodies, isocyanurate bodies, and adduct bodies that are a reaction product with low molecular active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil. Among these, trimethylolpropane-modified aromatic polyisocyanate, particularly trimethylolpropane-modified tolylene diisocyanate and trimethylolpropane-modified xylylene diisocyanate are preferable from the viewpoint of reactivity with hydroxyl groups.

  Examples of the epoxy crosslinking agent include 1,3-bis (N, N′-diglycidylaminomethyl) cyclohexane, N, N, N ′, N′-tetraglycidyl-m-xylylenediamine, ethylene glycol diglycidyl. Examples include ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidyl aniline, diglycidyl amine and the like.

  It is preferable that the usage-amount of a crosslinking agent (B) is 0.1-10 mass parts with respect to 100 mass parts of (meth) acrylic acid ester polymer (A), and is 0.3-5 mass parts especially. It is preferable that it is 0.3 to 3 parts by mass.

  When a pressure-sensitive adhesive composition containing a (meth) acrylic acid ester polymer (A) containing a reactive functional group-containing monomer as a monomer unit constituting the polymer and a crosslinking agent (B) is heated, a crosslinking agent ( B) reacts with the reactive functional group of the reactive functional group-containing monomer constituting the (meth) acrylic acid ester polymer (A). Thereby, the structure by which (meth) acrylic acid ester polymer (A) was bridge | crosslinked with the crosslinking agent (B) is formed, and the intensity | strength and durability of the obtained adhesive layer improve.

  A tackifier may be added to the pressure-sensitive adhesive forming the first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 22. By adding the tackifier, the first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 22 of the thin film can easily exhibit a desired pressure-sensitive adhesive force.

  The tackifier is not particularly limited. For example, polymerized rosin, polymerized rosin ester, rosin derivatives such as rosin derivatives, polyterpene resins, aromatic modified terpene resins and hydrides thereof, terpene phenol resins, coumarone Examples thereof include indene resins, aliphatic petroleum resins, aromatic petroleum resins and their hydrides, aliphatic / aromatic copolymer petroleum resins, and low molecular mass coalesces of styrene or substituted styrene. These may be used individually by 1 type and may be used in combination of 2 or more type.

  In the case of adding a tackifier, the content of the tackifier is preferably 2 with respect to 100 parts by mass of the (meth) acrylic acid ester polymer (A) from the viewpoint of achieving both high adhesive strength and low peeling strength. -90 mass parts, More preferably, it is 15-70 mass parts.

  Among the above, from polymerized rosin ester and rosin resin excluding aromatic modified terpene resin, terpene phenol resin, aliphatic petroleum resin, aromatic petroleum resin, aliphatic / aromatic copolymer petroleum resin, and polymerized rosin ester It is preferable to use a combination with at least one selected, and it is particularly preferable to use a combination of a polymerized rosin ester and an aromatic petroleum resin. Thereby, the characteristic outstanding in both surfaces, such as adhesive force and curved surface sticking property, can be exhibited.

  From such a viewpoint, the polymerized rosin ester is preferably added in an amount of 1 to 50 parts by mass, more preferably 10 to 40 parts by mass, with respect to 100 parts by mass of the (meth) acrylic acid ester polymer (A). From the same viewpoint, the aromatic petroleum resin is preferably added in an amount of 1 to 40 parts by mass, and more preferably 5 to 30 parts by mass with respect to 100 parts by mass of the (meth) acrylic acid ester polymer (A).

  The pressure-sensitive adhesive forming the first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 22 may contain other components. Examples of such components include additives such as antistatic agents, antioxidants, ultraviolet absorbers, light stabilizers, softeners, silane coupling agents, and fillers.

  The first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 22 may be formed from different pressure-sensitive adhesives, but are preferably formed from the same pressure-sensitive adhesive. When the first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 22 are formed of the same pressure-sensitive adhesive, the difference between the peeling force of the first peeling sheet 31 and the peeling force of the second peeling sheet 32 is determined. In particular, when the first release sheet 31 and the second release sheet 32 are made of the same material, the release force of the first release sheet 31 and the release force of the second release sheet 32 can be reduced. The difference with can be eliminated. Moreover, the adhesive force of the 1st adhesive layer 21 and the adhesive force of the 2nd adhesive layer 22 can be made easy to be the same, and when using the double-sided adhesive sheet 1, the 1st adhesive layer 21 and the 2nd There is no need to use the adhesive layer 22 separately.

  The adhesive strength of the first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 22 to a stainless steel plate (# 360 polished surface) according to JIS Z0237: 2009 is preferably 2000 to 30000 mN / 25 mm, respectively. It is preferably 3000 to 20000 mN / 25 mm, more preferably 5000 to 15000 mN / 25 mm. Moreover, it is preferable that the adhesive force of the 1st adhesive layer 21 and the adhesive force of the 2nd adhesive layer 22 are the same.

(3) First Release Sheet / Second Release Sheet In the double-sided pressure-sensitive adhesive sheet 1 according to the present embodiment, the first release sheet 31 is formed so that the release surface is in contact with the first pressure-sensitive adhesive layer 21. The second release sheet 32 is laminated with the second pressure-sensitive adhesive layer 22 so that the release surface is in contact with the second pressure-sensitive adhesive layer 22. In addition, the release surface of the release sheet in this specification refers to a surface having peelability in the release sheet, and includes both a surface that has been subjected to a release treatment and a surface that exhibits peelability without being subjected to a release treatment. .

  The first release sheet 31 and the second release sheet 32 in the double-sided pressure-sensitive adhesive sheet 1 according to the present embodiment are not particularly limited as long as they have the aforementioned peeling force and peeling force difference.

  Examples of the first release sheet 31 and the second release sheet 32 include a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, a vinyl chloride copolymer film, and a polyethylene terephthalate. Film, polyethylene naphthalate film, polybutylene terephthalate film, polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene / (meth) acrylic acid copolymer film, ethylene / (meth) acrylic acid ester copolymer film, polystyrene A film, a polycarbonate film, a polyimide film, a fluororesin film, or the like is used. These crosslinked films are also used. Furthermore, these laminated films may be sufficient.

  The release surfaces of the first release sheet 31 and the second release sheet 32 are preferably subjected to a release treatment. Examples of the release agent used for the release treatment include silicone-based, fluorine-based, alkyd-based, unsaturated polyester-based, polyolefin-based, and wax-based release agents. When the 1st adhesive layer 21 and the 2nd adhesive layer 22 consist of an acrylic adhesive, a silicone type release agent is preferable among the above. According to the silicone release agent, the first release sheet 31 and the second release sheet 32 are likely to have the above-described peeling force and peeling force difference.

Examples of the silicone release agent include a first organopolysiloxane having at least two alkenyl groups (for example, a vinyl group) in one molecule and a second organopolysiloxane having at least two hydrosilyl groups in one molecule. Those containing an addition reaction type silicone resin obtained from siloxane (corresponding to a crosslinking agent) and a silicone resin can be preferably used. As the silicone resin, for example, an MQ resin composed of an M unit which is a monofunctional siloxane unit [(CH ₃ ) ₃ SiO _1/2 ] and a Q unit which is a tetrafunctional siloxane unit [SiO _4/2 ] is used. Can be used. In the silicone release agent as described above, the desired release force can be obtained by adjusting the hardness of the release agent layer by the skeleton of the addition reaction type silicone resin and adjusting the surface polarity by the blending amount of the silicone resin. Can do.

  The thickness of the first release sheet 31 and the second release sheet 32 is not particularly limited, but is preferably a thickness corresponding to the thin film adhesive laminate 2, and preferably 12 to 100 μm, In particular, the thickness is preferably 20 to 75 μm, and more preferably 25 to 38 μm.

  The first release sheet 31 and the second release sheet 32 may be made of different materials, but are preferably made of the same material. When the first release sheet 31 and the second release sheet 32 are made of the same material, the difference between the release force of the first release sheet 31 and the release force of the second release sheet 32 can be easily reduced. In particular, when the first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 22 are formed of the same pressure-sensitive adhesive, the peeling force of the first peeling sheet 31 and the peeling force of the second peeling sheet 32 Can eliminate the difference.

[Method for producing double-sided PSA sheet]
The double-sided pressure-sensitive adhesive sheet 1 according to the present embodiment can be produced by a conventional method, but in order to control the adhesive force of the first adhesive layer 21 and the adhesive force of the second adhesive layer 22, the following It is preferable to manufacture by a method.

  The first pressure-sensitive adhesive layer 21 is formed on the release surface of the first release sheet 31, and the formed first pressure-sensitive adhesive layer 21 is laminated (transferred) on one surface of the substrate 20. Further, the second pressure-sensitive adhesive layer 22 is formed on the release surface of the second release sheet 32, and the formed second pressure-sensitive adhesive layer 22 is laminated (transferred) on the other surface of the substrate 20.

  The first pressure-sensitive adhesive layer 21 is a roll coater, knife coater, roll knife coater, air knife coater, which is prepared by preparing a coating agent containing the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer 21 and, if desired, a solvent. It can be formed by applying to the release surface of the first release sheet 31 with a coating machine such as a die coater, bar coater, gravure coater or curtain coater and drying. Similarly, the second pressure-sensitive adhesive layer 22 can be formed by applying to the release surface of the second release sheet 32 and drying.

  In the conventional manufacturing method, after forming the first pressure-sensitive adhesive layer on the release surface of the first release sheet and laminating (transferring) the formed first pressure-sensitive adhesive layer on one surface of the substrate 20 The second pressure-sensitive adhesive layer 22 was directly formed on the other surface of the substrate 20. In this case, when the pressure-sensitive adhesive constituting the second pressure-sensitive adhesive layer 22 is applied to the other surface of the substrate 20 and dried, the first pressure-sensitive adhesive layer formed on one surface of the substrate 20 is applied to the first pressure-sensitive adhesive layer. Also, heat was applied, whereby the adhesive strength of the first adhesive layer was reduced. On the other hand, according to the above manufacturing method, the first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 22 are formed separately, so that the first problem does not occur with the above-described problem of lowering the pressure-sensitive adhesive force. The adhesive force of the adhesive layer 21 and the adhesive force of the second adhesive layer 22 can be controlled. That is, when the pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer 21 and the pressure-sensitive adhesive constituting the second pressure-sensitive adhesive layer 22 are the same, the pressure-sensitive adhesive force of the first pressure-sensitive adhesive layer 21 and the pressure-sensitive adhesive The adhesive strength of the two adhesive layers 22 can be made the same.

  In the above embodiment, the first pressure-sensitive adhesive layer 21 is first laminated on the base material 20 and the second pressure-sensitive adhesive layer 22 is laminated on the base material 20 later. Two pressure-sensitive adhesive layers 22 may be laminated on the base material 20, and the first pressure-sensitive adhesive layer 21 may be laminated on the base material 20 later.

[Uses of double-sided PSA sheet]
The double-sided pressure-sensitive adhesive sheet 1 according to the present embodiment can be used for joining various members, and can be suitably used for joining members in products that are particularly required to be thin. For example, joining of members in various electronic devices such as a mobile phone, a portable information terminal, a smartphone, a tablet terminal, a notebook personal computer, an electronic dictionary, a digital music player, a digital video player, a portable game device, a portable GPS terminal, and a camera Can be used. Examples of the member to be joined include a substrate, various electronic components, a heat radiation sheet, an electromagnetic wave shielding sheet, and a gas barrier sheet.

  The embodiment described above is described for facilitating understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

  For example, another layer may be provided between the base material 20 and the first pressure-sensitive adhesive layer 21 and / or the second pressure-sensitive adhesive layer 22 in the double-sided pressure-sensitive adhesive sheet 1.

  EXAMPLES Hereinafter, although an Example etc. demonstrate this invention further more concretely, the scope of the present invention is not limited to these Examples etc.

[Example 1]
1. Preparation of (meth) acrylic acid ester polymer 97 parts by mass of n-butyl acrylate, 1 part by mass of acrylic acid, 0.5 part by mass of 2-hydroxyethyl acrylate, and 3 parts by mass of vinyl acetate were copolymerized, A (meth) acrylic acid ester polymer was prepared. When the molecular weight of this (meth) acrylic acid ester polymer was measured by the method described later, the weight average molecular weight (Mw) was 1,000,000.

2. Preparation of pressure-sensitive adhesive 100 parts by mass of the (meth) acrylic acid ester polymer obtained in Step 1 above (converted to solid content; the same applies hereinafter) and trimethylolpropane-modified tolylene diisocyanate (manufactured by Nippon Polyurethane Co., Ltd.) , Trade name "Coronate L") 1 part by mass, polymerized rosin ester as a tackifier (manufactured by Harima Kasei Co., Ltd., trade name "Halitak FK100"), and aromatic petroleum resin (Mitsui) as a tackifier Chemical Co., Ltd., trade name “FTR6100”) was mixed with 20 parts by mass, sufficiently stirred, and diluted with methyl ethyl ketone to obtain a pressure-sensitive adhesive coating solution (solid content: 10% by mass).

3. Formation of first adhesive layer As a first release sheet, a release sheet (SP-PET 1130, manufactured by Lintec Corporation, thickness: 25 μm) obtained by releasing one side of a polyethylene terephthalate (PET) film with a silicone release agent is used. Prepared. The pressure-sensitive adhesive coating solution obtained in step 2 above is applied to the release-treated surface of the first release sheet with a knife coater so that the thickness after drying is 2 μm, and then heated at 90 ° C. for 1 minute. It processed and formed the 1st adhesive layer.

  The formed first pressure-sensitive adhesive layer is laminated on one surface of a PET film (made by Mitsubishi Plastics, trade name “Diafoil K100-2.0W”, thickness: 2 μm) as a base material. (Transfer) to obtain a laminate composed of the first release sheet / first pressure-sensitive adhesive layer / base material.

4. Preparation of double-sided PSA sheet A release sheet (SP-PET1130, manufactured by Lintec Corporation, thickness: 25 µm) prepared by peeling one surface of a PET film with a silicone-based release agent was prepared as a second release sheet. The pressure-sensitive adhesive coating solution obtained in step 2 above is applied to the release-treated surface of the second release sheet with a knife coater so that the thickness after drying is 2 μm, and then heated at 90 ° C. for 1 minute. A second pressure-sensitive adhesive layer was formed by processing.

  The formed second pressure-sensitive adhesive layer is laminated and transferred (transferred) to the other surface (exposed surface) of the base material in the laminate obtained in the above step 3, and the first release sheet / first A double-sided PSA sheet consisting of 1 PSA layer / base material / second PSA layer / second release sheet was obtained.

[Example 2]
The pressure-sensitive adhesive coating solution obtained in Step 2 of Example 1 is dried on the other surface (exposed surface) of the base material in the laminate obtained in Step 3 of Example 1 so that the thickness after drying becomes 2 μm. Thus, after apply | coating with a knife coater, it heat-processed at 90 degreeC for 1 minute, and formed the 2nd adhesive layer.

  The second release sheet that is the same as that of Example 1 is bonded to the formed second pressure-sensitive adhesive layer so that the release-treated surface is in contact with the second pressure-sensitive adhesive layer. And laminated to obtain a double-sided pressure-sensitive adhesive sheet comprising the first release sheet / first pressure-sensitive adhesive layer / base material / second pressure-sensitive adhesive layer / second release sheet.

[Comparative Example 1]
Example 1 with the exception of using a release sheet (Lintec Corporation, SP-PET1031, thickness: 25 μm) obtained by subjecting one side of a PET film to a release treatment with a silicone-based release agent as the first release sheet and the second release sheet. Similarly, a double-sided PSA sheet was produced.

[Comparative Example 2]
As the first release sheet, a double-sided pressure-sensitive adhesive sheet was used in the same manner as in Example 1 except that a release sheet (SP-PET1031, thickness: 25 μm, manufactured by Lintec Co., Ltd.) obtained by releasing one side of a PET film with a silicone release agent was used. Was made.

Here, the above-mentioned weight average molecular weight (Mw) is a polystyrene-reduced weight average molecular weight measured under the following conditions (GPC measurement) using gel permeation chromatography (GPC).
<Measurement conditions>
GPC measurement device: manufactured by Tosoh Corporation, HLC-8020
GPC column (passed in the following order): TSK guard column HXL-H manufactured by Tosoh Corporation
TSK gel GMHXL (× 2)
TSK gel G2000HXL
・ Measurement solvent: Tetrahydrofuran ・ Measurement temperature: 40 ° C.

[Test Example 1] (Measurement of peel force)
The double-sided pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples were cut into 125 mm × 25 mm, and the second release sheet was peeled off from the double-sided pressure-sensitive adhesive sheet in an environment of 23 ° C. and 50% RH, and exposed second. The pressure-sensitive adhesive layer was affixed to a PET film (trade name “Lumirror T-61M”, thickness: 25 μm, manufactured by Toray Industries, Inc.). And the PET film side of the obtained laminate was fixed to a stainless steel plate.

  Next, in the environment of 23 ° C. and 50% RH, the force when peeling the first release sheet from the laminate in the 180 ° direction at a tensile speed of 300 mm / min in accordance with ISO 8510-2: 1990 is measured. This was taken as the peel force (mN / 25 mm). Similarly, the peel force when the second release sheet was peeled was measured. The results are shown in Table 1.

[Test Example 2] (Peelability evaluation)
In the double-sided pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples, a peeling starting point portion is formed between the first release sheet and the first pressure-sensitive adhesive layer, and the first release sheet is removed from the first pressure-sensitive adhesive layer. It peeled. At this time, it was visually confirmed whether or not floating occurred between the pressure-sensitive adhesive layer (second pressure-sensitive adhesive layer) and the second release sheet. As a result, the case where there was no float was evaluated as ◯, and the case where there was a float was evaluated as x.

  Similarly, when the second release sheet is peeled off, it is visually confirmed whether or not floating occurs between the pressure-sensitive adhesive layer (first pressure-sensitive adhesive layer) and the first release sheet. ,evaluated. The results are shown in Table 1.

[Test Example 3] (Measurement of adhesive strength)
The double-sided pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples were cut into 250 mm × 25 mm, and the second release sheet was peeled off from the double-sided pressure-sensitive adhesive sheet in an environment of 23 ° C. and 50% RH to expose the second adhesive sheet. The pressure-sensitive adhesive layer was affixed to a PET film (trade name “Lumirror T-61M”, thickness: 25 μm, manufactured by Toray Industries, Inc.). Next, the first release sheet was peeled from the double-sided pressure-sensitive adhesive sheet, and the exposed first pressure-sensitive adhesive layer was attached to a stainless steel plate (# 360 polished surface).

  Thereafter, in an environment of 23 ° C. and 50% RH, the force when peeling the double-sided pressure-sensitive adhesive sheet from the stainless steel plate in the 180 ° direction at a tensile speed of 300 mm / min in accordance with JIS Z0237: 2009, This was defined as adhesive strength (mN / 25 mm). Similarly, the adhesive force when the second adhesive layer was peeled from the stainless steel plate was measured. The results are shown in Table 1.

  As can be seen from Table 1, the double-sided pressure-sensitive adhesive sheets obtained in Examples 1 and 2 had the same peeling force even when the release sheet was peeled from any of them, and no lifting occurred. . Moreover, in the double-sided adhesive sheet obtained in Example 1, the 1st adhesive layer and the 2nd adhesive layer showed the same adhesive force.

  The double-sided pressure-sensitive adhesive sheet according to the present invention is suitable for manufacturing, for example, portable electronic devices that are required to be thin, such as smartphones and tablet terminals. Moreover, the manufacturing method of the double-sided adhesive sheet which concerns on this invention is suitable for manufacturing such a double-sided adhesive sheet.

DESCRIPTION OF SYMBOLS 1 ... Double-sided adhesive sheet 2 ... Adhesive laminated body 20 ... Base material 21 ... 1st adhesive layer 22 ... 2nd adhesive layer 31 ... 1st release sheet 32 ... 2nd release sheet

Claims (7)

A pressure-sensitive adhesive laminate comprising a base material, a first pressure-sensitive adhesive layer laminated on one surface side of the base material, and a second pressure-sensitive adhesive layer laminated on the other surface side of the base material; ,
A first release sheet laminated on the surface opposite to the base in the first pressure-sensitive adhesive layer;
A double-sided pressure-sensitive adhesive sheet comprising a second release sheet laminated on the side opposite to the substrate in the second pressure-sensitive adhesive layer,
The substrate has a thickness of 1 to 5 μm,
The thickness of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer is 1 to 5 μm, respectively.
The peeling force of the first release sheet and the second release sheet is 10 to 30 mN / 25 mm,
The double-sided pressure-sensitive adhesive sheet, wherein the difference between the peeling force of the first release sheet and the peeling force of the second release sheet is 5 mN / 25 mm or less.   The double-sided pressure-sensitive adhesive sheet according to claim 1, wherein the first release sheet and the second release sheet are made of the same material.   The double-sided pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer are made of the same pressure-sensitive adhesive.   The double-sided pressure-sensitive adhesive sheet according to any one of claims 1 to 3, wherein the pressure-sensitive adhesive forming the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer is an acrylic pressure-sensitive adhesive.   The double-sided pressure-sensitive adhesive sheet according to any one of claims 1 to 4, wherein the pressure-sensitive adhesive forming the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer contains a tackifier.   The double-sided pressure-sensitive adhesive sheet according to claim 5, wherein the pressure-sensitive adhesive contains a polymerized rosin ester and an aromatic petroleum resin as the tackifier. A method for producing the double-sided pressure-sensitive adhesive sheet according to any one of claims 1 to 6,
Forming a first pressure-sensitive adhesive layer on the release surface of the first release sheet;
Laminating the first pressure-sensitive adhesive layer formed on the release surface of the first release sheet on one surface side of the substrate;
Forming a second pressure-sensitive adhesive layer on the release surface of the second release sheet;
And a step of laminating the second pressure-sensitive adhesive layer formed on the release surface of the second release sheet on the other surface side of the base material.

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