WO2024063092A1 - Adhesive tape - Google Patents

Adhesive tape Download PDF

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Publication number
WO2024063092A1
WO2024063092A1 PCT/JP2023/034089 JP2023034089W WO2024063092A1 WO 2024063092 A1 WO2024063092 A1 WO 2024063092A1 JP 2023034089 W JP2023034089 W JP 2023034089W WO 2024063092 A1 WO2024063092 A1 WO 2024063092A1
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WO
WIPO (PCT)
Prior art keywords
mass
adhesive layer
meth
adhesive
acrylic copolymer
Prior art date
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PCT/JP2023/034089
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French (fr)
Japanese (ja)
Inventor
友也 川本
雄大 緒方
智基 戸田
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積水化学工業株式会社
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Publication of WO2024063092A1 publication Critical patent/WO2024063092A1/en

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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
    • C09J11/02—Non-macromolecular additives
    • C09J11/06—Non-macromolecular additives organic
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
    • C09J11/08—Macromolecular additives
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J133/00—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Adhesives based on derivatives of such polymers
    • C09J133/04—Homopolymers or copolymers of esters
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J175/00—Adhesives based on polyureas or polyurethanes; Adhesives based on derivatives of such polymers
    • C09J175/04—Polyurethanes
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/20—Adhesives in the form of films or foils characterised by their carriers
    • C09J7/22—Plastics; Metallised plastics
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
    • C09J7/38—Pressure-sensitive adhesives [PSA]

Definitions

  • the present invention relates to an adhesive tape.
  • Adhesive tapes are used for assembly in portable electronic devices such as mobile phones and personal digital assistants (PDAs) (for example, Patent Documents 1 and 2). Adhesive tapes are also used for bonding optical members together (for example, Patent Document 3).
  • the functions required for the adhesive layer include retention performance consisting of bulk cohesive force and heat resistance, and adhesiveness consisting of interfacial wettability and bulk fluidity.
  • the molecular weight of components such as (meth)acrylic copolymers needed to be approximately 500,000 or more in order to satisfy these properties.
  • An object of the present invention is to provide a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer having excellent retention performance and adhesiveness even though it uses a (meth)acrylic copolymer having a low molecular weight.
  • the present disclosure 1 is an adhesive tape having an adhesive layer, the adhesive layer containing a crosslinked product of an adhesive containing a (meth)acrylic copolymer, a crosslinking agent, and a tackifying resin,
  • the weight of the (meth)acrylic copolymer obtained by alkaline decomposition of the crosslinking points of the crosslinked product in the region of molecular weight 5000 or more when GPC measurement is performed using differential refractometer RI detection.
  • the above-mentioned adhesive tape has an average molecular weight of 80,000 or more and is less than 500,000, and is bonded to a SUS plate.
  • the adhesive tape does not fall in a holding test in which a 1 kg load is applied in the shear direction at 80°C for 24 hours, and the adhesive tape does not fall off against the SUS plate.
  • the adhesive tape has a 180° peeling adhesive strength of 15 N/25 mm or more.
  • the present disclosure 2 is an adhesive tape having an adhesive layer, wherein the adhesive layer contains a crosslinked product of an adhesive containing a (meth)acrylic copolymer, a crosslinking agent, and a tackifying resin,
  • the weight of the (meth)acrylic copolymer obtained by alkaline decomposition of the crosslinking points of the crosslinked product in the region of molecular weight 5000 or more when GPC measurement is performed using differential refractometer RI detection.
  • the adhesive tape has an average molecular weight of 80,000 or more and less than 500,000, and satisfies the following first configuration, the following second configuration, or the following third configuration.
  • the adhesive contains 6 parts by mass or more of the crosslinking agent based on 100 parts by mass of the (meth)acrylic copolymer, and the gel fraction of the adhesive layer is 5% by mass or more.
  • a second configuration the adhesive contains 6 parts by mass or more of the crosslinking agent based on 100 parts by mass of the (meth)acrylic copolymer, and the adhesive layer has a gel fraction of less than 5% by mass.
  • the adhesive contains 0.1 parts by mass or more and less than 6 parts by mass of the crosslinking agent based on 100 parts by mass of the (meth)acrylic copolymer, and the adhesive layer contains Present Disclosure 3, in which the gel fraction exceeds 30% by mass, is the adhesive tape of Present Disclosure 2 that satisfies the above first configuration.
  • the present disclosure 4 is the adhesive tape of the present disclosure 2 that satisfies the second configuration.
  • the present disclosure 5 is the adhesive tape of the present disclosure 2 that satisfies the third configuration.
  • the present disclosure 6 is the adhesive tape according to the present disclosure 1, in which the adhesive layer satisfies the following first configuration, the following second configuration, or the following third configuration.
  • First configuration The adhesive contains 6 parts by mass or more of the crosslinking agent based on 100 parts by mass of the (meth)acrylic copolymer, and the gel fraction of the adhesive layer is 5% by mass or more.
  • a second configuration the adhesive contains 6 parts by mass or more of the crosslinking agent based on 100 parts by mass of the (meth)acrylic copolymer, and the adhesive layer has a gel fraction of less than 5% by mass.
  • the alkali decomposition of the crosslinking point of the crosslinked product is determined.
  • the value obtained by subtracting the weight average molecular weight of the (meth)acrylic copolymer in the molecular weight region of 5,000 or more was 80,000.
  • the adhesive contains 0.1 parts by mass or more and less than 6 parts by mass of the crosslinking agent based on 100 parts by mass of the (meth)acrylic copolymer, and the adhesive layer contains In the present disclosure 7, in which the gel fraction exceeds 30% by mass, the adhesive layer has the first configuration, and the adhesive contains the crosslinking agent based on 100 parts by mass of the (meth)acrylic copolymer.
  • the adhesive has the above (meth) Present Disclosure 2 or 6, wherein the crosslinking agent is contained in 1.5 parts by mass or more and less than 6 parts by mass based on 100 parts by mass of the acrylic copolymer, and the adhesive layer has a gel fraction of more than 30% by mass.
  • This is an adhesive tape.
  • the present disclosure 8 provides that the adhesive layer has the first configuration, wherein the adhesive contains 6 parts by mass or more of the crosslinking agent based on 100 parts by mass of the (meth)acrylic copolymer, and
  • the adhesive tape of the present disclosure 7 has a configuration in which the adhesive layer has a gel fraction of 5% by mass or more and less than 30% by mass.
  • the adhesive layer has the third configuration, and the adhesive contains 1.5 parts by mass or more and 6 parts by mass of the crosslinking agent based on 100 parts by mass of the (meth)acrylic copolymer.
  • the pressure-sensitive adhesive tape of the present disclosure 7 has a structure in which the gel fraction of the pressure-sensitive adhesive layer exceeds 30% by mass.
  • Present disclosure 10 is a book in which the weight average molecular weight of the sol component of the adhesive layer in a region of molecular weight 5000 or more is 50,000 or more and 500,000 or less when GPC measurement is performed using differential refractometer RI detection.
  • the adhesive tape of Disclosure 1, 2, 3, 4, 5, 6, 7, 8 or 9.
  • This disclosure 11 discloses that the (meth)acrylic copolymer obtained by alkaline decomposition of the crosslinking point of the crosslinked product is subjected to GPC measurement using differential refractometer RI detection, and the (meth) The adhesive tape of the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, wherein the peak top molecular weight of the acrylic copolymer is 70,000 or more and 300,000 or less.
  • This disclosure 12 provides that the adhesive contains 0.03% by mass or more of a compound having a hydroxyl group in the solid content, and 2% or more by mass of the compound having a carboxy group in the solid content of the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or 11 adhesive tape.
  • Present disclosure 13 provides that the above-mentioned (meth)acrylic copolymer has 50% by mass or more of a structural unit derived from a monomer having an alkyl group having 6 or more carbon atoms. , 7, 8, 9, 10, 11 or 12 adhesive tape.
  • Present disclosure 14 is the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, or 13 adhesive tape.
  • the present disclosure 15 is the present disclosure 1, 2, 3, 4, 5, 6, 7, wherein the adhesive layer has a storage modulus G' (80 °C) of 1.0 ⁇ 10 4 Pa or more, No. 8, 9, 10, 11, 12, 13 or 14 adhesive tape.
  • This disclosure 16 provides that the adhesive layer has a thickness of 10 ⁇ m or more and 100 ⁇ m or less.
  • This is an adhesive tape.
  • Present Disclosure 17 provides Present Disclosures 1 and 2, wherein the adhesive tape has a base material, the base material is a polyester resin film or a polypropylene resin film, and the thickness of the base material is 5 ⁇ m or more and 200 ⁇ m or less. , 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 or 16 adhesive tapes.
  • Present disclosure 18 is the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, wherein the adhesive tape has a base material, and the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, No. 11, 12, 13, 14, 15, 16 or 17 adhesive tape.
  • the present invention will be explained in detail below.
  • the adhesive tape of the present disclosure 1 is also referred to as the "adhesive tape of the present invention 1"
  • the adhesive tape of the present disclosure 2 is also referred to as the “adhesive tape of the present invention 2”.
  • matters common to the adhesive tape of the first invention and the adhesive tape of the second invention are not specified or are described as "the adhesive tape of the invention”.
  • the present inventors believe that even when an adhesive containing a (meth)acrylic copolymer having a specific low molecular weight is used to form an adhesive layer, the adhesive layer has a specific configuration. The inventors have discovered that, by doing so, it is possible to obtain an adhesive tape having an adhesive layer with excellent retention performance and adhesive properties, and have completed the present invention.
  • the adhesive tape of the present invention is an adhesive tape having an adhesive layer.
  • the adhesive layer contains a crosslinked adhesive product containing a (meth)acrylic copolymer, a crosslinking agent, and a tackifying resin.
  • (meth)acrylic means acrylic or methacryl.
  • the adhesive layer has a molecular weight of 5,000 or more when GPC measurement using differential refractometer RI detection is performed on a (meth)acrylic copolymer obtained by alkaline decomposition of the crosslinking points of the crosslinked product.
  • the weight average molecular weight of the (meth)acrylic copolymer in the range (hereinafter also simply referred to as "the weight average molecular weight of the (meth)acrylic copolymer obtained by alkaline decomposition”) is 80,000 or more and less than 500,000.
  • the weight average molecular weight of the (meth)acrylic copolymer obtained by the above alkaline decomposition is 80,000 or more, the bulk cohesive force in the resulting adhesive layer is increased, and the adhesive layer has excellent heat resistance. becomes. Since the weight average molecular weight of the (meth)acrylic copolymer obtained by the alkali decomposition is less than 500,000, the viscosity of the adhesive used to form the adhesive layer can be lowered, and processability is improved. In addition, it is possible to reduce the amount of solvent that is the source of CO 2 emitted during the manufacturing process.
  • the preferable lower limit of the weight average molecular weight of the (meth)acrylic copolymer obtained by the above alkaline decomposition is 100,000, the more preferable lower limit is 150,000, the preferable upper limit is 490,000, the more preferable upper limit is 450,000, and the even more preferable upper limit is is 400,000.
  • the above-mentioned "(meth)acrylic copolymer obtained by alkaline decomposition” may be the (meth)acrylic copolymer contained in the above-mentioned adhesive, or may be any other compound. Good too.
  • Examples of other compounds include (meth)acrylic copolymers in which part of the structure of the (meth)acrylic copolymer contained in the pressure-sensitive adhesive is modified and/or deleted. Further, alkaline decomposition of the crosslinking points of the crosslinked product is performed by the following method. That is, 300 mg of the above adhesive layer, 6 mL of ethanol, and 7 mL of 60% KOH aqueous solution were added to a pressure vessel, and the mixture was hydrolyzed under pressure in an oven at 160°C for 60 hours to alkali decompose the crosslinking points of the crosslinked product and convert it into (meth) ) Obtain an acrylic copolymer.
  • the following method can be adopted. That is, the (meth)acrylic copolymer obtained by alkaline decomposition of the crosslinking points of the crosslinked product was analyzed by gel permeation chromatography (GPC) (manufactured by Waters, "2690 Separations Model"), and the polystyrene equivalent Measure the molecular weight distribution by The above GPC can be performed under the following conditions.
  • GPC gel permeation chromatography
  • the adhesive layer has a molecular weight of 5,000 or more when GPC measurement using differential refractometer RI detection is performed on a (meth)acrylic copolymer obtained by alkaline decomposition of the crosslinking points of the crosslinked product.
  • the preferable lower limit of the peak top molecular weight of the (meth)acrylic copolymer in the region (hereinafter also simply referred to as "the peak top molecular weight of the (meth)acrylic copolymer obtained by alkaline decomposition") is 70,000, and the preferable upper limit is 70,000. It is 300,000.
  • the peak top molecular weight of the (meth)acrylic copolymer obtained by the above-mentioned alkaline decomposition is 70,000 or more, the bulk cohesive force in the resulting adhesive layer becomes larger, and the adhesive layer has better heat resistance. Become something. Since the peak top molecular weight of the (meth)acrylic copolymer obtained by the alkali decomposition is 300,000 or less, the viscosity of the adhesive used to form the adhesive layer can be lowered, and processing It is possible to further improve the properties and further reduce the amount of solvent, which is the source of CO 2 emitted during the manufacturing process.
  • a more preferable lower limit of the peak top molecular weight of the (meth)acrylic copolymer obtained by the alkali decomposition is 80,000, an even more preferable lower limit is 100,000, a more preferable upper limit is 250,000, and an even more preferable upper limit is 230,000.
  • peak top molecular weight means the molecular weight at the highest peak in a molecular weight distribution curve. Even if there is a shoulder or two or more peaks in the molecular weight distribution curve, the peak top molecular weight means the molecular weight at the highest peak in the molecular weight distribution curve.
  • the polydispersity of the (meth)acrylic copolymer obtained by alkaline decomposition of the crosslinking points of the crosslinked product in a molecular weight region of 5,000 or more when the (meth)acrylic copolymer is subjected to GPC measurement with RI detection using a differential refractometer (hereinafter also simply referred to as "polydispersity of the (meth)acrylic copolymer obtained by alkaline decomposition”) is preferably 15,000 in lower limit, and preferably 100,000 in upper limit, more preferably 60,000 in upper limit.
  • the polydispersity refers to the ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn).
  • the adhesive layer has a weight average molecular weight (hereinafter referred to as The preferable lower limit of the weight average molecular weight (also simply referred to as "weight average molecular weight of the sol component”) is 50,000, and the preferable upper limit is 500,000.
  • the weight average molecular weight of the sol component is 50,000 or more, the bulk cohesive force in the resulting adhesive layer becomes larger, and the adhesive layer has better heat resistance and high-temperature repulsion resistance.
  • the weight average molecular weight of the sol component is 500,000 or less, the viscosity of the adhesive used to form the adhesive layer can be lowered, and processability can be further improved, The amount of solvent that is the source of CO 2 emitted during the manufacturing process can be further reduced.
  • a more preferable lower limit of the weight average molecular weight of the sol component is 70,000, an even more preferable lower limit is 100,000, a more preferable upper limit is 400,000, and an even more preferable upper limit is 300,000.
  • the above-mentioned "sol component” means a component obtained by removing the "gel component” from the above-mentioned adhesive layer. Note that the above-mentioned “gel component” remains in the mesh during the gel fraction measurement process in which the above-mentioned (meth)acrylic copolymer, tackifying resin, etc. described below construct a cross-linked structure via the cross-linking agent described later.
  • the above-mentioned "sol component” is a component with high fluidity from which the gel component has been removed by the above treatment.
  • the sol component of the adhesive layer can be obtained by, for example, immersing the adhesive layer in tetrahydrofuran (THF) at 23°C for 24 hours and filtering the insoluble matter through a 200 mesh wire mesh to remove the gel component. Obtainable.
  • GPC gel permeation chromatography
  • the sol component of the adhesive layer is analyzed by gel permeation chromatography (GPC) (manufactured by Waters, "2690 Separations Model”) to measure the molecular weight distribution in terms of polystyrene.
  • the adhesive layer has a peak top molecular weight (hereinafter referred to as (also simply referred to as "peak top molecular weight of the sol component”) has a preferable lower limit of 30,000, and a preferable upper limit of 300,000.
  • peak top molecular weight of the above-mentioned sol component is 30,000 or more, the bulk cohesive force in the resulting adhesive layer becomes larger, and the adhesive layer has better heat resistance.
  • the peak top molecular weight of the sol component By setting the peak top molecular weight of the sol component to 300,000 or less, the viscosity of the adhesive used to form the adhesive layer can be lowered, and processability can be further improved, The amount of solvent that is the source of CO 2 emitted during the manufacturing process can be further reduced.
  • a more preferable lower limit of the peak top molecular weight of the sol component is 70,000, an even more preferable lower limit is 80,000, a more preferable upper limit is 250,000, and an even more preferable upper limit is 230,000.
  • the adhesive tape of the present invention 1 does not fall when a holding test is performed in which a 1 kg load is applied in the shear direction at 80° C. for 24 hours after being bonded to a SUS plate.
  • the adhesive tape that shows the results of the above-mentioned retention test has excellent heat resistance, and can be well fixed to members used in electronic devices, for example.
  • As a result of the above-mentioned retention test it is preferable that there is no deviation of 1 mm or more, and it is more preferable that there is no deviation of 0.5 mm or more.
  • the adhesive tape of the second aspect of the present invention does not fall when subjected to a holding test in which a 1 kg load is applied in the shear direction at 80° C.
  • the adhesive tape exhibiting the results of the above-mentioned retention test has better heat resistance, and can be better fixed to members used in electronic devices, for example.
  • the above retention test it is more preferable that there is no deviation of 1 mm or more, and even more preferably that there is no deviation of 0.5 mm or more.
  • the above retention test can be performed by the following method. Moreover, a schematic diagram showing the method of the above-mentioned retention test is shown in FIG. That is, first, the adhesive tape 1 is cut into strips with a width of 25 mm, and then bonded to the SUS board 2 by moving a 2 kg rubber roller back and forth at a speed of 300 mm/min.
  • a cut is made in the adhesive tape 1 so that the adhesive area is 25 mm x 25 mm. After that, it was left to stand at 23°C for 20 minutes, then placed in an oven at 80°C, and heated for another 15 minutes. Apply load in the shear direction. Check to see if the adhesive tape has fallen, and if it has not fallen after 24 hours, measure the amount of movement (displacement) from the cut position using a scale loupe.
  • the adhesive tape of the present invention 1 has a 180° peeling adhesive strength of 15 N/25 mm or more to an SUS board. Specifically, after bonding with a SUS plate, a 180° peeling adhesive force was 15N when a tensile test was performed in a 180° direction at 23°C and a peeling speed of 300 mm/min in accordance with JIS Z0237. /25mm or more.
  • the 180° peeling adhesive force is preferably 18 N/25 mm or more, more preferably 20 N/25 mm or more.
  • the adhesive tape of the present invention 2 has a 180° peeling adhesive strength of 15 N/25 mm or more to an SUS board. Specifically, after bonding with a SUS plate, a 180° peeling adhesive force was 15N when a tensile test was performed in a 180° direction at 23°C and a peeling speed of 300 mm/min in accordance with JIS Z0237. /25 mm or more is preferable.
  • the adhesive tape can have more sufficient adhesive properties, and can be better fixed to members used in electronic devices, for example.
  • the 180° peeling adhesive force is more preferably 18 N/25 mm or more, and even more preferably 20 N/25 mm or more.
  • the above 180° peeling adhesive strength can be measured by the following method. That is, first, an adhesive tape is cut into strips with a width of 25 mm, and then bonded to an SUS plate by moving a 2 kg rubber roller back and forth at a speed of 300 mm/min. Next, a test piece is obtained by allowing it to stand for 20 minutes at a temperature of 23° C. and a relative humidity of 50%.
  • the obtained test piece was subjected to a tensile test using a tensile testing machine in accordance with JIS Z0237 under the conditions of 23°C, peeling speed of 300 mm/min, and peeling angle of 180°, and the above 180° peeling adhesive strength was determined. can be measured.
  • the adhesive layer satisfies the following first configuration, the following second configuration, or the following third configuration. Further, in the adhesive tape of the present invention 1, the adhesive layer preferably satisfies the following first configuration, the following second configuration, or the following third configuration.
  • First configuration The adhesive contains 6 parts by mass or more of the crosslinking agent based on 100 parts by mass of the (meth)acrylic copolymer, and the gel fraction of the adhesive layer is 5% by mass or more.
  • a second configuration the adhesive contains 6 parts by mass or more of the crosslinking agent based on 100 parts by mass of the (meth)acrylic copolymer, and the adhesive layer has a gel fraction of less than 5% by mass.
  • the alkali decomposition of the crosslinking point of the crosslinked product is determined.
  • the value obtained by subtracting the weight average molecular weight of the (meth)acrylic copolymer in the molecular weight region of 5,000 or more was 80,000.
  • the adhesive contains 0.1 parts by mass or more and less than 6 parts by mass of the crosslinking agent based on 100 parts by mass of the (meth)acrylic copolymer, and the adhesive layer contains
  • the adhesive tape of the present invention 2 having a gel fraction of more than 30% by mass
  • the adhesive layer is obtained by satisfying the first configuration, the second configuration, or the third configuration.
  • the layer has excellent retention performance and adhesion.
  • the adhesive layer satisfies the first configuration, the second configuration, or the third configuration, so that the resulting adhesive layer has good retention performance and adhesive properties. It becomes better.
  • the adhesive contains 6 parts by mass or more of the crosslinking agent based on 100 parts by mass of the (meth)acrylic copolymer, and the gel fraction of the adhesive layer is 5% by mass. If it is above, the bulk cohesive force in the resulting adhesive layer will be large, and the adhesive layer will have excellent heat resistance. This is because even if the molecular weight of the (meth)acrylic copolymer is small and the gel fraction is low, if the number of crosslinking agent parts is large, it can be considered that crosslinking and polymerization within the sol component are progressing.
  • the gel fraction of the pressure-sensitive adhesive layer is preferably 10% by mass or more, more preferably 15% by mass or more.
  • the adhesive layer preferably has a gel fraction of less than 30% by mass.
  • the adhesive layer has a gel fraction of less than 30% by mass, thereby suppressing a decrease in bulk fluidity due to an increase in the elastic modulus of the adhesive layer, and allowing the adhesive layer to This results in better adhesion without significantly reducing the wettability of the adhesive.
  • the adhesive layer preferably has a gel fraction of 28% by mass or less.
  • the content of the crosslinking agent in the pressure-sensitive adhesive based on 100 parts by mass of the (meth)acrylic copolymer is preferably 12 parts by mass or less.
  • the content of the crosslinking agent in the adhesive is 12 parts by mass or less, thereby suppressing a decrease in bulk fluidity due to an increase in the elastic modulus of the adhesive layer.
  • the adhesion is improved without significantly reducing the wettability of the interface.
  • the content of the crosslinking agent in the pressure-sensitive adhesive is more preferably 10 parts by mass or less.
  • the weight average molecular weight of the sol component of the adhesive layer in the region of molecular weight 5,000 or more when GPC measurement is performed using differential refractometer RI detection is The value obtained by subtracting the weight average molecular weight of the (meth)acrylic copolymer is 80,000 or more.
  • the preferable lower limit of the gel fraction of the pressure-sensitive adhesive layer is 0.1% by mass, and the more preferable lower limit is 1% by mass. Further, in the second configuration, the preferable lower limit of the value obtained by subtracting the weight average molecular weight of the (meth)acrylic copolymer obtained by the alkaline decomposition from the weight average molecular weight of the sol component is 100,000, and the more preferable lower limit is 12 Ten thousand.
  • the adhesive layer when the gel fraction of the adhesive layer exceeds 30% by mass, the bulk cohesive force in the adhesive layer increases, and the adhesive layer has excellent heat resistance.
  • the gel fraction of the adhesive layer is preferably 31% by mass or more, more preferably 35% by mass or more, even more preferably 40% by mass or more, and 45% by mass. % or more is even more preferable.
  • the adhesive layer preferably has a gel fraction of 70% by mass or less. In the third configuration, the gel fraction of the adhesive layer is 70% by mass or less, thereby suppressing a decrease in bulk fluidity in the adhesive layer and improving the wettability of the interface. The adhesive properties are improved without significantly decreasing the adhesive properties.
  • the gel fraction of the pressure-sensitive adhesive layer is more preferably 65% by mass or less, and even more preferably 60% by mass or less. Furthermore, in the third configuration, the content of the crosslinking agent in the pressure-sensitive adhesive based on 100 parts by mass of the (meth)acrylic copolymer is preferably 0.1 part by mass or more. In the third configuration, when the content of the crosslinking agent in the adhesive is 0.1 parts by mass or more, the gel fraction of the resulting adhesive layer tends to increase, and the bulk cohesive force becomes larger. . In the third configuration, the content of the crosslinking agent in the pressure-sensitive adhesive is more preferably 1.5 parts by mass or more, and even more preferably 2 parts by mass or more.
  • the adhesive layer has the first configuration, wherein the adhesive contains 6 parts by mass or more of the crosslinking agent based on 100 parts by mass of the (meth)acrylic copolymer, and the adhesive layer contains a gel of the adhesive layer.
  • the adhesive has a composition in which the fraction is 5% by mass or more and less than 30% by mass, or as the third composition, the adhesive contains the crosslinking agent based on 100 parts by mass of the (meth)acrylic copolymer. It is preferable that the pressure-sensitive adhesive layer contains 1.5 parts by mass or more and less than 6 parts by mass, and the gel fraction of the pressure-sensitive adhesive layer exceeds 30% by mass.
  • the weight average molecular weight, peak top molecular weight, and polydispersity of the (meth)acrylic copolymer obtained by the above alkaline decomposition, the weight average molecular weight and peak top molecular weight of the sol component The method for adjusting the value obtained by subtracting the weight average molecular weight of the (meth)acrylic copolymer obtained by the alkali decomposition from the weight average molecular weight of the sol component to the above range is not particularly limited.
  • the (meth)acrylic copolymer contained in the pressure-sensitive adhesive a method using a (meth)acrylic copolymer obtained by a polymerization method such as living radical polymerization or free radical polymerization may be mentioned.
  • a method using a (meth)acrylic copolymer obtained by free radical polymerization is preferred.
  • living radical polymerization is preferred from the viewpoint of uniformly introducing crosslinking points.
  • the weight average molecular weight of the (meth)acrylic copolymer obtained by the above polymerization method the weight average molecular weight and peak top molecular weight of the (meth)acrylic copolymer obtained by the above alkaline decomposition can be adjusted. be able to.
  • the (meth)acrylic copolymers obtained by the above polymerization method use a (meth)acrylic copolymer obtained under relatively mild polymerization conditions such as keeping the polymerization temperature and monomer mixture concentration constant. is preferred. This makes it possible to make the composition of the above-mentioned (meth)acrylic copolymer more uniform and to reduce the polydispersity of the (meth)acrylic copolymer obtained by the above-mentioned alkaline decomposition, so that the pressure-sensitive adhesive layer can be It becomes easier to adjust the molecular weight distribution of the sol components.
  • Polymerization methods that require relatively mild polymerization conditions include, for example, free radical constant temperature polymerization, and free radical boiling point polymerization in which half of the monomer mixture and a polymerization initiator are charged into the reactor. Examples include a method in which the remaining half of the monomer mixture is added dropwise or all at once after initiation of polymerization.
  • the reaction is preferably carried out for 2 to 10 hours. If the polymerization time is not appropriately adjusted, the free radical polymerization causes the crosslinking points of the polymer chain to be introduced non-uniformly due to the high reaction rate of the crosslinkable functional group-containing monomer, or causes a large amount of residual monomer to remain, resulting in a decrease in creep resistance.
  • the polymerization reaction time in the polymerization method is preferably 2 hours at the lower limit and 10 hours at the upper limit. By setting the polymerization reaction time in this range, it becomes easier to adjust the weight average molecular weight of the (meth)acrylic copolymer obtained by the alkaline decomposition to the above-mentioned range.
  • the polymerization reaction time is more preferably 3 hours at the lower limit and 8 hours at the upper limit.
  • Examples of the polymerization initiator used in the above polymerization method include azo compounds, organic peroxides, and the like.
  • Examples of the above azo compounds include 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), ), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 1,1-azobis(cyclohexane-1-carbonitrile), 1-((1-cyano-1-methylethyl)azo ) formamide, 4,4'-azobis(4-cyanovaleric acid), dimethyl-2,2'-azobis(2-methylpropionate), dimethyl-1,1'-azobis(1-cyclohexanecarboxylate), 2,2'-azobis(2-methyl-N-(1,1'-bis(hydroxymethyl)-2-hydroxyethyl)propionamide), 2,2'-azobis(2-methyl-
  • organic peroxides examples include 1,1-bis(t-hexylperoxy)-3,3,5-trimethylcyclohexane, t-hexylperoxypivalate, t-butylperoxypivalate, 2,5 -dimethyl-2,5-bis(2-ethylhexanoylperoxy)hexane, t-hexylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxy Examples include isobutyrate, t-butylperoxy-3,5,5-trimethylhexanoate, and t-butylperoxylaurate. These organic peroxides may be used alone or in combination of two or more.
  • polymerization initiators having a functional group are preferred.
  • a polymerization initiator having the above-mentioned functional group it is possible to introduce a functional group to the terminal of the above-mentioned (meth)acrylic copolymer.
  • a functional group can also be introduced at the end of a molecular chain having a relatively small molecular weight and lacking in constituent units derived from the monomer contained therein. Since such low molecular chains have a functional group at the end, they are incorporated into the crosslinked structure via the crosslinking agent described below, so that the bulk cohesive force in the resulting adhesive layer is increased, and the adhesive layer is It has better heat resistance.
  • the low molecular chain has a functional group at the end, so that it can be connected to the crosslinking agent described below or with the tackifier resin described below.
  • the low molecular chains can form a conjugate (for example, a dimer, etc.) via the conjugate.
  • the (meth)acrylic copolymer contained in the sol component of the pressure-sensitive adhesive layer has a high molecular weight as a whole. Therefore, the weight average molecular weight, etc. of the sol component can be easily adjusted within the above-mentioned range, and the bulk cohesive force in the resulting adhesive layer becomes larger, resulting in the adhesive layer having better heat resistance.
  • Examples of the functional group include a hydroxyl group, a carboxy group, a silyl group, a glycidyl group, an amino group, an amide group, a nitrile group, an alkoxy group, and an acetoacetyl group.
  • hydroxyl and carboxy groups are preferred.
  • examples of the polymerization initiator having the above functional group include 2,2'-azobis(2-methyl-N-(1,1'-bis(hydroxymethyl)-2-hydroxyethyl) ) propionamide), 4,4'-azobis(4-cyanovaleric acid (valeric acid)), and the like. Polymerization initiators having these functional groups may be used alone or in combination of two or more.
  • the preferable lower limit of the amount of the polymerization initiator added is 0.01 part by weight, and the preferable upper limit is 0.5 parts by weight, based on 100 parts by weight of the monomer mixture. When the polymerization initiator is within this range, it becomes easy to adjust the weight average molecular weight, etc. of the sol component to the above range.
  • a more preferable lower limit of the amount of the polymerization initiator added is 0.02 parts by mass, and a more preferable upper limit is 0.3 parts by mass.
  • a chain transfer agent may be used.
  • the chain transfer agent include lauryl mercaptan, mercaptopropionic acid, mercaptosuccinic acid, 3-mercapto-1,2-propanediol, 1-butanethiol, cyclohexyl 3-mercaptopropionate, 2-ethylhexyl mercaptoacetate, 1
  • examples include thiol compounds such as -hexadecanethiol, 2-mercaptoethanol, mercaptoacetic acid, ethyl mercaptoacetate, 1-octanethiol, tridecyl 3-mercaptopropionate, and thiophenol.
  • 2,4-diphenyl-4-methyl-1-pentene and the like are also included. These chain transfer agents may be used alone or in combination of two or more.
  • chain transfer agents it is preferable to use a chain transfer agent having a functional group.
  • a chain transfer agent having the above-mentioned functional group it becomes easier to adjust the weight average molecular weight, etc. of the above-mentioned sol component to the above-mentioned range. That is, by using a chain transfer agent having the above-mentioned functional group, it is possible to introduce a functional group to the end of the above-mentioned low molecular chain in the same way as when using a polymerization initiator having the above-mentioned functional group, and as a result, , the bulk cohesive force in the resulting adhesive layer becomes larger, and the adhesive layer has better creep resistance.
  • the functional group examples include a hydroxyl group, a carboxy group, a silyl group, a glycidyl group, an amino group, an amide group, a nitrile group, an alkoxy group, and an acetoacetyl group.
  • hydroxyl group and carboxy group are preferred, and hydroxyl group is more preferred.
  • the crosslinking reaction of low molecular chains can be advantageously promoted by using a chain transfer agent that has a hydroxyl group as a functional group to insert a hydroxyl group at the end of the low molecular chain.
  • the number of functional groups in the chain transfer agent having the above-mentioned functional groups is preferably multivalent, since the crosslinked structure tends to have higher dimensions, becomes easier to form a network, and the bulk cohesive force in the pressure-sensitive adhesive layer becomes larger.
  • examples of the chain transfer agent having the above functional group include mercaptopropionic acid, mercaptosuccinic acid, 3-mercapto-1,2-propanediol, and the like. Chain transfer agents having these functional groups may be used alone or in combination of two or more.
  • the preferable lower limit of the amount of the chain transfer agent added is 0.01 part by weight and the preferable upper limit is 0.5 part by weight based on 100 parts by weight of the monomer mixture. When the amount of the chain transfer agent added is within this range, it becomes easy to adjust the weight average molecular weight, etc. of the sol component to the above range.
  • a more preferable lower limit of the amount of the chain transfer agent added is 0.02 parts by mass, and a more preferable upper limit is 0.3 parts by mass.
  • a dispersion stabilizer may be used.
  • the dispersion stabilizer include polyvinylpyrrolidone, polyvinyl alcohol, methylcellulose, ethylcellulose, poly(meth)acrylic acid, poly(meth)acrylic acid ester, polyethylene glycol, and the like. These dispersion stabilizers may be used alone or in combination of two or more.
  • examples of the polymerization solvent include nonpolar solvents such as hexane, cyclohexane, octane, toluene, and xylene, water, methanol, ethanol, propanol, butanol, acetone, methyl ethyl ketone, and methyl Highly polar solvents such as isobutyl ketone, tetrahydrofuran, dioxane, N,N-dimethylformamide, etc. can be used. These polymerization solvents may be used alone or in combination of two or more.
  • the polymerization temperature in the free radical polymerization is preferably 0° C. to 110° C. from the viewpoint of polymerization rate.
  • the (meth)acrylic copolymer preferably has a structural unit derived from a monomer having an alkyl group having 6 or more carbon atoms.
  • the alkyl group having 6 or more carbon atoms in the monomer having an alkyl group having 6 or more carbon atoms preferably has 6 or more carbon atoms and 16 or less carbon atoms.
  • the above (meth)acrylic copolymer has a structural unit derived from a monomer having an alkyl group having 6 or more and 16 or less carbon atoms, the bulk fluidity of the resulting adhesive layer increases, and the adhesive layer has better adhesion to rough surfaces.
  • the alkyl group having 6 or more carbon atoms in the monomer having an alkyl group having 6 or more carbon atoms more preferably has 6 or more carbon atoms and 12 or less carbon atoms. Further, in the monomer having an alkyl group having 6 or more carbon atoms, the alkyl group having 6 or more carbon atoms may or may not have a branch, but it is preferable that the alkyl group has no branch.
  • the adhesive layer Since the alkyl group of the monomer having an alkyl group having 6 or more carbon atoms does not have a branch, the adhesive layer has a low storage modulus at low to normal temperatures, but a high storage modulus at high temperatures. Therefore, it has better heat resistance and better adhesion to rough surfaces.
  • Examples of the monomer having an alkyl group having 6 or more carbon atoms include alkyl (meth)acrylates having an alkyl group having 6 or more carbon atoms.
  • Examples of the alkyl (meth)acrylate having an alkyl group having 6 or more carbon atoms include n-heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-octyl (meth)acrylate, isooctyl (meth)acrylate, Examples include n-nonyl (meth)acrylate, isononyl (meth)acrylate, lauryl (meth)acrylate, myristyl (meth)acrylate, cetyl (meth)acrylate, isostearyl acrylate, arachidyl (meth)acrylate, and the like.
  • alkyl (meth)acrylates having an alkyl group having 6 or more carbon atoms may be used alone, or two or more types may be used in combination. Among them, n-heptyl (meth)acrylate and 2-ethylhexyl (meth)acrylate are preferred.
  • the said "(meth)acrylate” means acrylate or methacrylate.
  • a preferable lower limit of the content of the structural unit derived from the monomer having an alkyl group having 6 or more carbon atoms in the (meth)acrylic copolymer is 50% by mass.
  • the glass transition temperature of the (meth)acrylic copolymer is lowered, and the resulting adhesive layer
  • the bulk fluidity of the adhesive layer increases, and the adhesive layer has better adhesion to rough surfaces.
  • the bulk of the adhesive layer becomes more flexible and the viscosity of the adhesive solution is further reduced, so that processability is further improved.
  • the compatibility with the tackifying resin described later is also improved.
  • a more preferable lower limit of the content of the structural unit derived from the monomer having an alkyl group having 6 or more carbon atoms is 60% by mass, and an even more preferable lower limit is 70% by mass.
  • the preferable upper limit of the content of the structural unit derived from the monomer having an alkyl group having 6 or more carbon atoms in the (meth)acrylic copolymer is 98% by mass. Since the content of the structural unit derived from the monomer having an alkyl group having 6 or more carbon atoms is 98% by mass or less, the glass transition temperature of the (meth)acrylic copolymer does not become too low, and the resulting The bulk cohesive force in the pressure-sensitive adhesive layer becomes larger, and the pressure-sensitive adhesive layer has better heat resistance.
  • a more preferable upper limit of the content of the structural unit derived from the monomer having an alkyl group having 6 or more carbon atoms is 97% by mass, and an even more preferable upper limit is 95% by mass.
  • the (meth)acrylic copolymer may have a structural unit derived from an alkyl (meth)acrylate having an alkyl group having 5 or less carbon atoms.
  • alkyl (meth)acrylate having an alkyl group having 5 or less carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, and butyl (meth)acrylate.
  • Examples include acrylate.
  • These alkyl (meth)acrylates having an alkyl group having 5 or less carbon atoms may be used alone, or two or more types may be used in combination. Among them, butyl (meth)acrylate is preferred.
  • the content of the structural unit derived from the alkyl (meth)acrylate having an alkyl group having 5 or less carbon atoms is preferably 25% by mass or more and less than 50% by mass.
  • the glass transition temperature of the (meth)acrylic copolymer becomes sufficiently high. Therefore, the bulk cohesive force in the resulting adhesive layer becomes larger, and the adhesive layer has better heat resistance.
  • the content ratio is less than 50% by mass, the glass transition temperature of the (meth)acrylic copolymer will not become too high, the bulk fluidity of the resulting adhesive layer will increase, and the adhesive layer will be It has better adhesion to rough surfaces.
  • a more preferable lower limit of the content ratio is 30% by mass, and a more preferable upper limit is 45% by mass.
  • the (meth)acrylic copolymer preferably has a structural unit derived from a crosslinkable functional group-containing monomer. Since the (meth)acrylic copolymer has a structural unit derived from the crosslinkable functional group-containing monomer, the (meth)acrylic copolymer and the tackifying resin described below are crosslinked via the crosslinking agent described below. By constructing the structure, the bulk cohesive force in the resulting adhesive layer becomes larger, and the adhesive layer has better heat resistance.
  • crosslinkable functional group examples include a hydroxyl group, a carboxy group, a silyl group, a glycidyl group, an amino group, an amide group, a nitrile group, an alkoxy group, and an acetoacetyl group.
  • hydroxyl groups and carboxy groups are preferred because the bulk cohesive force in the pressure-sensitive adhesive layer can be easily adjusted.
  • crosslinkable functional group-containing monomer having a hydroxyl group as the crosslinkable functional group examples include 4-hydroxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, and hydroxypropyl (meth)acrylate.
  • examples of the crosslinkable functional group-containing monomer having a carboxy group as the crosslinkable functional group include (meth)acrylic acid, itaconic acid, maleic anhydride, crotonic acid, maleic acid, fumaric acid, etc. Of these, acrylic acid is preferred.
  • An example of the crosslinkable functional group-containing monomer having a glycidyl group as the crosslinkable functional group is glycidyl (meth)acrylate.
  • crosslinkable functional group-containing monomer having an amide group as the crosslinkable functional group examples include hydroxyethylacrylamide, isopropylacrylamide, and dimethylaminopropylacrylamide.
  • examples of the crosslinkable functional group-containing monomer having a nitrile group as the crosslinkable functional group include acrylonitrile.
  • the preferable lower limit of the content of the structural unit derived from the crosslinkable functional group-containing monomer in the (meth)acrylic copolymer is 0.05% by mass, and the preferable upper limit is 20% by mass.
  • the content of the structural unit derived from the crosslinkable functional group-containing monomer is 0.05% by mass or more, the bulk cohesive force in the resulting adhesive layer becomes larger, and the adhesive layer has better heat resistance.
  • the content of the structural unit derived from the crosslinkable functional group-containing monomer is 20% by mass or less, the bulk fluidity of the resulting adhesive layer increases, and the adhesive layer has better adhesion to rough surfaces. Become something.
  • a more preferable lower limit of the content of the structural units derived from the crosslinkable functional group-containing monomer is 0.1% by mass, and a more preferable upper limit is 15% by mass.
  • the preferable content ratio of the structural unit derived from the crosslinkable functional group-containing monomer is The lower limit is 0.03% by mass, and the preferable upper limit is 1% by mass.
  • the content of the structural unit derived from the crosslinkable functional group-containing monomer having a hydroxyl group as the crosslinkable functional group is 0.03% by mass or more, the bulk cohesive force in the resulting adhesive layer becomes larger, The adhesive layer has better heat resistance.
  • the content of the structural unit derived from the crosslinkable functional group-containing monomer having a hydroxyl group as the crosslinkable functional group is 1% by mass or less, the gel fraction of the resulting pressure-sensitive adhesive layer does not become too high.
  • the adhesive layer has better adhesion to rough surfaces.
  • a more preferable lower limit of the content ratio of the structural unit derived from a crosslinkable functional group-containing monomer having a hydroxyl group as the crosslinkable functional group is 0.05% by mass, an even more preferable lower limit is 0.06% by mass, and a more preferable upper limit is The upper limit is preferably 0.5% by weight, more preferably 0.3% by weight, and particularly preferably 0.1% by weight.
  • the content of the structural unit derived from the crosslinkable functional group-containing monomer having a carboxy group as the crosslinkable functional group is 2% by mass, and the preferable upper limit is 15% by mass.
  • the content of the structural unit derived from the crosslinkable functional group-containing monomer having a carboxyl group as the crosslinkable functional group is 2% by mass or more, the gel fraction of the resulting adhesive layer tends to be high, and the above ( Since the glass transition temperature of the meth)acrylic copolymer becomes sufficiently high, the bulk cohesive force in the resulting pressure-sensitive adhesive layer becomes larger.
  • the adhesive layer has better heat resistance.
  • the content of the structural unit derived from the crosslinkable functional group-containing monomer having a carboxyl group as the crosslinkable functional group is 15% by mass or less, the glass transition temperature of the (meth)acrylic copolymer becomes too high. Without this, the adhesive layer has better adhesion to rough surfaces.
  • a more preferable lower limit of the content of the structural unit derived from the crosslinkable functional group-containing monomer having a carboxyl group as the crosslinkable functional group is 3% by mass, an even more preferable lower limit is 5% by mass, and a more preferable upper limit is 10% by mass. A more preferable upper limit is 8% by mass.
  • the above-mentioned (meth)acrylic copolymer is derived from a structural unit derived from the above-mentioned monomer having an alkyl group having 6 or more carbon atoms, or an alkyl (meth)acrylate having the above-mentioned alkyl group having 5 or less carbon atoms, as necessary. It may have a structural unit and a structural unit derived from another polymerizable monomer that can be copolymerized other than the structural unit derived from the above-mentioned crosslinkable functional group-containing monomer.
  • the pressure-sensitive adhesive includes a crosslinking agent.
  • a crosslinking agent for example, an isocyanate crosslinking agent, an aziridine crosslinking agent, an epoxy crosslinking agent, a metal chelate type crosslinking agent, etc. are selected depending on the type of crosslinkable functional group of the (meth)acrylic copolymer. It is used as Among these, isocyanate-based crosslinking agents are preferred because they can selectively crosslink hydroxyl groups and carboxyl groups and the crosslinked structure can be easily controlled. In particular, it is preferable that 80 parts by mass or more of an isocyanate-based crosslinking agent having two or more isocyanate units in one molecule is contained in 100 parts by mass of the crosslinking agent. Examples of commercially available isocyanate-based crosslinking agents include Coronate HX, Coronate L (all manufactured by Tosoh Corporation), Mytec NY260A (manufactured by Mitsubishi Chemical Corporation), and the like.
  • the number of functional groups in the crosslinking agent is preferably multivalent, since the crosslinked structure tends to have higher dimensions, becomes easier to form a network, and the bulk cohesive force in the resulting pressure-sensitive adhesive layer becomes larger.
  • the pressure-sensitive adhesive contains a tackifier resin.
  • the resulting pressure-sensitive adhesive layer has excellent adhesion to the adherend.
  • the preferable lower limit of the softening temperature of the tackifier resin is 90°C, and the preferable upper limit is 180°C.
  • the softening temperature of the tackifier resin is 90° C. or higher, the adhesive layer has better heat resistance, and the creep resistance at high temperatures is further improved.
  • the softening temperature of the tackifier resin is 180° C. or less, the adhesive layer becomes easily flexible and has excellent adhesiveness to rough surfaces.
  • a more preferable lower limit of the softening temperature of the tackifying resin is 100°C, an even more preferable lower limit is 110°C, an especially preferable lower limit is 120°C, a more preferable upper limit is 170°C, and an even more preferable upper limit is 165°C.
  • the above-mentioned "softening temperature” means the softening temperature measured by JIS K2207 ring and ball method.
  • the preferable lower limit of the hydroxyl value of the tackifying resin is 10 mgKOH/g, and the preferable upper limit is 200 mgKOH/g.
  • the hydroxyl value of the tackifier resin is 10 mgKOH/g or more, the softening temperature of the tackifier resin tends to be high.
  • the reactivity with the crosslinking agent will not become too high, and the crosslinking of the (meth)acrylic copolymer will not be inhibited or the (meth)acrylic copolymer will not be inhibited. It is possible to suppress a graft reaction from occurring with the polymer.
  • a more preferable lower limit of the hydroxyl value of the tackifier resin is 20 mgKOH/g, an even more preferable lower limit is 25 mgKOH/g, an especially preferable lower limit is 30 mgKOH/g, a more preferable upper limit is 150 mgKOH/g, an even more preferable upper limit is 120 mgKOH/g, A particularly preferable upper limit is 100 mgKOH/g.
  • the above-mentioned "hydroxyl value" can be measured according to JIS K1557 (phthalic anhydride method).
  • tackifier resin examples include rosin resins such as rosin ester resins, terpene resins such as terpene phenol resins, petroleum resins, and the like. These tackifying resins may be used alone or in combination of two or more. Among these, rosin ester resins, terpene phenol resins, and combinations thereof are preferred, and terpene phenol resins are more preferred.
  • the above-mentioned terpene phenol resin is a resin obtained by polymerizing terpene in the presence of phenol.
  • the terpene phenol resin has good compatibility with the (meth)acrylic copolymer, is easily grafted with the (meth)acrylic copolymer, and is easily incorporated into the adhesive layer. Therefore, the surface of the pressure-sensitive adhesive layer becomes polymer-rich and flexible, and can have higher adhesive strength to rough surfaces.
  • the adhesive layer since the bulk cohesive force of the adhesive layer is further increased by grafting the terpene phenol resin and the (meth)acrylic copolymer, the adhesive layer has better creep resistance.
  • terpene resins commercially available ones include, for example, YS Polystar G150 (hydroxyl value 140 mgKOH/g, softening temperature 150°C), YS Polyster T100 (hydroxyl value 60 mgKOH/g, softening temperature 100°C), YS Polyster G125 (hydroxyl value 140mgKOH/g, softening temperature 125°C), YS Polyster T115 (hydroxyl value 60mgKOH/g, softening temperature 115°C), YS Polyster T130 (hydroxyl value 60mgKOH/g, softening temperature 130°C), YS Polyster T160 ( Hydroxyl value: 60 mgKOH/g, softening temperature: 160° C.) (both manufactured by Yasuhara Chemical Co., Ltd.).
  • the above-mentioned rosin ester resins are rosin resins whose main component is abietic acid, disproportionated rosin resins, hydrogenated rosin resins, dimers of resin acids such as abietic acid (polymerized rosin resins), etc., and esterified with alcohol.
  • This is a resin obtained by A part of the hydroxyl group of the alcohol used for esterification is not used for esterification but is contained in the resin, so that the hydroxyl value is adjusted to the above-mentioned range.
  • the alcohol include polyhydric alcohols such as ethylene glycol, glycerin, and pentaerythritol.
  • resin obtained by esterifying rosin resin is called rosin ester resin
  • resin obtained by esterifying disproportionated rosin resin is called disproportionated rosin ester resin
  • resin obtained by esterifying hydrogenated rosin resin is called hydrogenated rosin ester resin
  • polymerized rosin resin A resin obtained by esterifying a resin is a polymerized rosin ester resin.
  • disproportionated rosin ester resins include, for example, Super Ester A75 (hydroxyl value 23 mgKOH/g, softening temperature 75°C), Super Ester A100 (hydroxyl value 16 mgKOH/g, softening temperature 100°C). , Super Ester A115 (hydroxyl value: 19 mgKOH/g, softening temperature: 115°C), Super Ester A125 (hydroxyl value: 15 mgKOH/g, softening temperature: 125°C) (all manufactured by Arakawa Chemical Industries, Ltd.).
  • Examples of the hydrogenated rosin ester resin include Pine Crystal KE-359 (hydroxyl value 42 mgKOH/g, softening temperature 100°C), Ester Gum H (hydroxyl value 29 mgKOH/g, softening temperature 70°C) (both manufactured by Arakawa Chemical Co., Ltd. company), etc.
  • Examples of the polymerized rosin ester resin include Pencel D135 (hydroxyl value 45 mgKOH/g, softening temperature 135°C), Pencel D125 (hydroxyl value 34 mgKOH/g, softening temperature 125°C), Pencel D160 (hydroxyl value 42mgKOH/g, softening temperature 125°C), (temperature: 160° C.) (all manufactured by Arakawa Chemical Industries, Ltd.).
  • the content of the tackifier resin has a preferable lower limit of 10 parts by weight and a preferable upper limit of 60 parts by weight based on 100 parts by weight of the (meth)acrylic copolymer.
  • the adhesive layer has better interfacial adhesion and better retention performance.
  • a more preferable lower limit of the content is 15 parts by weight, an even more preferable lower limit is 20 parts by weight, a more preferable upper limit is 50 parts by weight, and an even more preferable upper limit is 45 parts by weight.
  • the pressure-sensitive adhesive may contain additives such as a solvent, a plasticizer, an emulsifier, a softener, a filler, a pigment, a dye, a silane coupling agent, and an antioxidant, as necessary.
  • additives such as a solvent, a plasticizer, an emulsifier, a softener, a filler, a pigment, a dye, a silane coupling agent, and an antioxidant, as necessary.
  • the pressure-sensitive adhesive contains 0.03% by mass or more of a compound having a hydroxyl group in the solid content, and 2% by mass or more of the compound having a carboxy group in the solid content.
  • Bulk cohesive strength in the adhesive layer obtained by the above-mentioned adhesive containing 0.03% by mass or more of a compound having a hydroxyl group in the solid content and 2% by mass or more of the compound having a carboxy group in the solid content becomes larger, and the adhesive layer has better heat resistance.
  • the pressure-sensitive adhesive contains 0.05% by mass or more of the compound having a hydroxyl group.
  • the above-mentioned pressure-sensitive adhesive contains 3% by mass or more of the above-mentioned compound having a carboxyl group.
  • the compound having a hydroxyl group and the compound having a carboxyl group may be any component contained in the solid content of the pressure-sensitive adhesive.
  • the above-mentioned "solid content” means components excluding the solvent.
  • the preferable upper limit of the viscosity when applying the above adhesive is 10,000 mPa ⁇ s. By having a viscosity of 10,000 mPa ⁇ s or less when applying the above-mentioned adhesive, it becomes easy to apply the adhesive smoothly without problems such as bubbles or adhesive streaks.
  • a more preferable upper limit of the viscosity when applying the pressure-sensitive adhesive is 9000 mPa ⁇ s, and an even more preferable upper limit is 8000 mPa ⁇ s.
  • the preferable lower limit of the viscosity when applying the above-mentioned pressure-sensitive adhesive is 1500 mPa ⁇ s.
  • a viscosity of 1500 mPa ⁇ s or more when applying the above-mentioned adhesive sufficient pressure can be obtained when extruding the adhesive, making it easy to apply the adhesive to the desired thickness and width.
  • a more preferable lower limit of the viscosity when applying the pressure-sensitive adhesive is 2000 mPa ⁇ s.
  • the viscosity when applying the adhesive can be measured using a B-type viscometer at 23° C. and 12 rpm.
  • the preferable lower limit of the glass transition temperature of the pressure-sensitive adhesive layer is -10°C, and the preferable upper limit is 30°C.
  • the glass transition temperature of the adhesive layer is ⁇ 10° C. or higher, the adhesive layer has high heat resistance and high bulk cohesive force, resulting in better retention performance and high-temperature repulsion resistance.
  • the glass transition temperature of the pressure-sensitive adhesive layer is 30° C. or lower, the adhesive layer has better adhesion to the interface.
  • a more preferable lower limit of the glass transition temperature of the pressure-sensitive adhesive layer is -5°C, an even more preferable lower limit is 0°C, an even more preferable lower limit is 5°C, a more preferable upper limit is 25°C, an even more preferable upper limit is 20°C, and an even more preferable upper limit.
  • the preferred upper limit is 15°C.
  • the above-mentioned "glass transition temperature” means the temperature at which the maximum due to micro-Brownian motion appears among the maximum loss tangent (tan ⁇ ) obtained by dynamic viscoelasticity measurement.
  • the following method can be adopted as the dynamic viscoelasticity measurement performed to measure the glass transition temperature of the adhesive layer and the storage modulus described below.
  • test piece samples of the above-mentioned pressure-sensitive adhesive layers are stacked to form a laminate having a thickness of about 1 mm, and the laminate is cut into a size of 6 mm x 10 mm to obtain a test piece.
  • the obtained test piece was measured using a dynamic viscoelasticity measuring device (IT Keizai Control Co., Ltd., "DVA-200") under a nitrogen atmosphere in shear mode at a measurement temperature of -40°C to 140°C and a heating rate of 5. Dynamic viscoelasticity measurements are performed at °C/min, frequency of 10 Hz, and strain of 0.08%.
  • a preferable lower limit of the storage modulus G' (80°C) of the adhesive layer at 80°C is 1.0 ⁇ 10 4 Pa.
  • the storage elastic modulus G' (80°C) of the adhesive layer By setting the storage elastic modulus G' (80°C) of the adhesive layer to be 1.0 ⁇ 10 4 Pa or more, the bulk cohesive force of the adhesive layer at high temperatures becomes greater, and the creep resistance at high temperatures and It has better high-temperature repulsion resistance.
  • a more preferable lower limit of the storage elastic modulus G' (80° C.) of the adhesive layer is 1.5 ⁇ 10 4 Pa, an even more preferable lower limit is 2.0 ⁇ 10 4 Pa, and an even more preferable lower limit is 5.0 ⁇ 10 4 Pa, a particularly preferable lower limit is 8.0 ⁇ 10 4 Pa. If the storage elastic modulus G' (80°C) of the adhesive layer is too high, the storage elastic modulus at room temperature will also be high and the adhesive force to rough surfaces will decrease.
  • C) is preferably 2.0 ⁇ 10 5 Pa.
  • the preferable lower limit of the thickness of the adhesive layer is 10 ⁇ m, and the preferable upper limit is 100 ⁇ m.
  • the thickness of the adhesive layer is 10 ⁇ m or more, the ability of the adhesive layer to penetrate into the adherend increases, and the peeling resistance increases, resulting in better adhesion to rough surfaces.
  • the thickness is 100 ⁇ m or less, the amount of displacement when a shearing force is applied to the adhesive layer is reduced, so that the adhesive layer has better retention performance.
  • a more preferable lower limit of the thickness of the adhesive layer is 12 ⁇ m, an even more preferable lower limit is 15 ⁇ m, a more preferable upper limit is 60 ⁇ m, and an even more preferable upper limit is 50 ⁇ m.
  • the adhesive tape has a base material.
  • a resin film is preferable.
  • the resin film is preferably a polyester resin film or a polypropylene resin film.
  • polyester resin films are preferred because they are flat, have small thickness fluctuations, and have high strength.
  • polyethylene terephthalate films are more preferred.
  • the base material may contain additives such as a filler, an ultraviolet absorber, a light stabilizer, and an antistatic agent within a range that does not impair its physical properties.
  • the thickness of the above-mentioned base material is appropriately selected depending on the intended use, and the preferable lower limit is 5 ⁇ m and the preferable upper limit is 200 ⁇ m.
  • the thickness of the base material is 200 ⁇ m or less, it becomes suitable for use in fixing electronic components, and it is possible to reduce CO 2 emissions during manufacturing.
  • a more preferable lower limit of the thickness of the base material is 10 ⁇ m, an even more preferable lower limit is 15 ⁇ m, a more preferable upper limit is 100 ⁇ m, and an even more preferable upper limit is 50 ⁇ m.
  • the adhesive tape of the present invention may have the adhesive layer on only one side of the base material, or may have the adhesive layer on both sides of the base material. Among these, it is preferable to have the adhesive layer on both sides of the base material.
  • the method for producing the adhesive tape of the present invention is not particularly limited, and for example, when the base material has adhesive layers having the same composition and thickness on both sides, the following method may be used.
  • the adhesive obtained above is applied to the release-treated side of the release film, one side of which has been subjected to the release treatment, and dried to form a laminated sheet having an adhesive layer on the release-treated side of the release film. Create.
  • a total of two laminated sheets are prepared in the same manner.
  • the pressure-sensitive adhesive layers of the two laminated sheets are transferred to the base material and laminated together to obtain a pressure-sensitive adhesive sheet having pressure-sensitive adhesive layers on both sides of the base material.
  • the adhesive tape of the present invention has excellent high-temperature repulsion resistance.
  • high-temperature repulsion resistance can be evaluated, for example, by the following method.
  • FIG. 2 shows a schematic diagram showing the method of high temperature repulsion resistance test. That is, after cutting the adhesive tape 1 of the present invention into a strip shape of 25 mm width x 300 mm length, the adhesive layer on the side not to be measured is pasted to a PET film 4 (thickness 100 ⁇ m, 25 mm width, length 300 mm).
  • the adhesive layer on the side to be measured was attached to the SUS plate 2 (SUS304 plate washed with ethanol and wiped dry) so that the short side of the adhesive tape 1 overlapped with one side of the SUS plate, and then a 2 kg rubber roller was attached.
  • the test pieces were prepared by standing at 23° C. for 72 hours. The prepared test piece was further heated in an oven at 80°C for 15 minutes, and then a 100g weight 5 was placed on the tip of the test piece at 80°C for the test piece placed horizontally.
  • a high temperature repulsion resistance test is conducted in which a load of 100 g is applied perpendicularly to the test piece and maintained for 144 hours.
  • the adhesive tape of the present invention has excellent high-temperature repulsion resistance.
  • a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer having excellent retention performance and adhesiveness even though it uses a (meth)acrylic copolymer having a low molecular weight.
  • FIG. 2 is a schematic diagram showing a method of high temperature repulsion resistance test.
  • each material in Table 1 is as follows.
  • BA Butyl acrylate 2EHA: 2-ethylhexyl acrylate C7: n-heptyl acrylate
  • HEA Hydroxyethyl acrylate
  • Aac Acrylic acid AIBN: 2,2'-azobis(isobutyronitrile)
  • Examples 1 to 23, Comparative Examples 1 to 8 (1) Preparation of Pressure-Sensitive Adhesives Each material was added to the solution containing the obtained acrylic copolymers A to S in the composition shown in Tables 2 and 3, and stirred to obtain pressure-sensitive adhesives. The content of the compound having a hydroxyl group in the solid content and the content of the compound having a carboxyl group in the solid content of the obtained pressure-sensitive adhesives are shown in Tables 2 and 3.
  • Tables 2 and 3 The materials in Tables 2 and 3 are as follows: Coronate L45: isocyanate-based crosslinking agent (manufactured by Tosoh Corporation) KE388: Hydrogenated rosin ester resin (manufactured by Arakawa Chemical Industries, Ltd., hydroxyl value 45 mgKOH/g, softening temperature 150° C.) KE359: Hydrogenated rosin ester resin (manufactured by Arakawa Chemical Industries, Ltd., hydroxyl value 40 mgKOH/g, softening temperature 100° C.) D135: Polymerized rosin ester resin (manufactured by Arakawa Chemical Industries, Ltd., hydroxyl value 40 mgKOH/g, softening temperature 135° C.) G150: Terpene resin (manufactured by Yasuhara Chemical Co., Ltd., hydroxyl value 100 mg KOH/g, softening temperature 150° C.)
  • One of the laminated sheets was laminated on one surface of this base material from the adhesive layer side, so that the adhesive layer was transferred and laminated onto the base material.
  • the other laminated sheet was laminated on the other surface of the base material from the pressure-sensitive adhesive layer side, so that the pressure-sensitive adhesive layer was transferred and laminated onto the base material.
  • a double-sided adhesive tape was obtained in which adhesive layers having the thicknesses shown in Tables 2 and 3 were provided on both sides of the base material.
  • the obtained (meth)acrylic copolymer was analyzed by gel permeation chromatography (GPC) (manufactured by Waters, "2690 Separations Model") to measure the molecular weight distribution in terms of polystyrene.
  • GPC gel permeation chromatography
  • Mw copolymer weight average molecular weight
  • Mp copolymer peak top molecular weight
  • Mn copolymer polydispersity
  • the adhesive layer of the obtained double-sided adhesive tape was immersed in tetrahydrofuran (THF) at 23°C for 24 hours, and the insoluble matter was removed by filtering through a 200 mesh wire mesh to obtain the sol component of the adhesive layer.
  • THF tetrahydrofuran
  • the sol component of the obtained adhesive layer was analyzed by gel permeation chromatography (GPC) (manufactured by Waters, "2690 Separations Model"), and the molecular weight distribution in terms of polystyrene was measured.
  • GPC gel permeation chromatography
  • Mw sol-Mw copolymer are shown in Tables 2 and 3.
  • the above GPC was performed under the following conditions.
  • Detector Differential refractometer RI
  • the adhesive layers of the obtained double-sided adhesive tapes were overlapped to produce a laminate with a thickness of about 1 mm, and the laminate was cut into a size of 6 mm x 10 mm to obtain a test piece.
  • the obtained test piece was measured using a dynamic viscoelasticity measuring device (IT Keizai Control Co., Ltd., "DVA-200") under a nitrogen atmosphere in shear mode at a measurement temperature of -40°C to 140°C and a heating rate of 5. Dynamic viscoelasticity was measured at a temperature of 10° C./min, a frequency of 10 Hz, and a strain of 0.08%, and the storage modulus G′ (80° C.) was obtained.
  • the temperature at which the maximum due to micro-Brownian motion appeared was defined as the glass transition temperature.
  • the obtained storage modulus G' (80° C.) and glass transition temperature are shown in Tables 2 and 3.
  • the resulting double-sided adhesive tape was cut into strips with a width of 25 mm, and then bonded to a SUS board (SUS304 board that had been washed with ethanol and wiped dry) by moving a 2 kg rubber roller back and forth at a speed of 300 mm/min. .
  • SUS board SUS304 board that had been washed with ethanol and wiped dry
  • cuts were made in the adhesive tape so that the adhesive area was 25 mm x 25 mm. After that, it was left to stand at 23°C for 20 minutes, then placed in an oven at 80°C, heated for another 15 minutes, and then, while being maintained at 80°C, a 1kg weight was applied using a 1kg weight 3 as shown in Figure 1. was added in the shear direction.
  • the adhesive tape was cut into strips with a width of 25 mm, and then bonded to an SUS board (SUS304 board washed with ethanol and wiped dry) by moving a 2 kg rubber roller back and forth at a speed of 300 mm/min.
  • SUS304 board washed with ethanol and wiped dry
  • a test piece was obtained by allowing it to stand for 20 minutes at a temperature of 23° C. and a relative humidity of 50%.
  • the obtained test piece was tested in accordance with JIS Z0237 using a tensile tester (manufactured by A&D Co., Ltd., "RTI-1310") at a temperature of 23°C, a peeling rate of 300 mm/min, and a peeling angle of 180°.
  • a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer having excellent retention performance and adhesiveness even though it uses a (meth)acrylic copolymer having a low molecular weight.
  • Adhesive tape SUS board 3 1kg load (weight) 4 PET film 5 100g load (weight)

Abstract

The purpose of the present invention is to provide an adhesive tape having an adhesive layer having excellent retention performance and adhesion even while using a low-molecular-weight (meth)acrylic copolymer. The present invention is an adhesive tape having an adhesive layer, wherein the adhesive layer contains a crosslinked product of an adhesive comprising a (meth)acrylic copolymer, a crosslinking agent, and a tackifying resin, the weight average molecular weight of the (meth)acrylic copolymer in the region of a molecular weight of 5000 or more is from 80,000 to less than 500,000 when the (meth)acrylic copolymer obtained by alkali decomposition of the crosslinking points of the crosslinked product is subjected to GPC measurement by differential refractometer RI detection, the adhesive tape bonded to an SUS plate does not fall off in a retention test that applies a 1 kg load for 24 hours in the shear direction at 80°C, and the 180° peel adhesion force of the adhesive tape to an SUS plate is 15 N/25 mm or more.

Description

粘着テープAdhesive tape
本発明は、粘着テープに関する。 The present invention relates to an adhesive tape.
携帯電話、携帯情報端末（Ｐｅｒｓｏｎａｌ　Ｄｉｇｉｔａｌ　Ａｓｓｉｓｔａｎｔｓ、ＰＤＡ）等の携帯電子機器においては、組み立てのために粘着テープが用いられている（例えば、特許文献１、２）。また、光学部材を貼り合わせる用途にも粘着テープが用いられている（例えば、特許文献３）。 Adhesive tapes are used for assembly in portable electronic devices such as mobile phones and personal digital assistants (PDAs) (for example, Patent Documents 1 and 2). Adhesive tapes are also used for bonding optical members together (for example, Patent Document 3).
特開２００９－２４２５４１号公報Japanese Patent Application Publication No. 2009-242541 特開２００９－２５８２７４号公報Japanese Patent Application Publication No. 2009-258274 特開２０１２－２１４５４４号公報JP 2012-214544 A
地球規模で考えるべき環境問題として、温室効果ガスによる地球温暖化がある。そして昨今、温室効果ガスの排出量から吸収量と除去量を差し引いた合計をゼロにするカーボンニュートラルという考え方が全世界で普及しつつある。粘着テープを使用部材とする電子デバイス分野においても環境対応製品創出の動きは加速している。
粘着テープの有する粘着剤層の形成に使用される粘着剤は、通常、溶剤を含むため、粘着テープの製造プロセスでは、該溶剤を由来としてＣＯ２が排出される。粘着剤に含まれる溶剤量を減らすことで製造プロセスにおいて排出されるＣＯ２を減らすことができるものの、単に溶剤量を減らしただけでは粘着剤の粘度が上昇し、加工性が低下するという問題がある。溶剤量を減らす、即ち、粘着剤の固形分の含有割合を高くしても粘度が上がらないようにするためには、粘着剤に含まれる（メタ）アクリル共重合体等の成分の分子量を低くする必要がある。一方、粘着剤層に必要な機能としては、バルクの凝集力及び耐熱性からなる保持性能と、界面の濡れ性及びバルクの流動性からなる接着性とが挙げられ、従来の粘着剤に使用される（メタ）アクリル共重合体等の成分は、これら性能を満たすために分子量を５０万程度以上とする必要があった。 Global warming caused by greenhouse gases is an environmental issue that should be considered on a global scale. Recently, the idea of carbon neutrality, which means that the total of greenhouse gas emissions minus absorption and removal is zero, is becoming popular around the world. The movement to create environmentally friendly products is also accelerating in the field of electronic devices that use adhesive tape as a component.
Since the adhesive used to form the adhesive layer of an adhesive tape usually contains a solvent, CO 2 is emitted from the solvent in the adhesive tape manufacturing process. Although it is possible to reduce CO2 emitted during the manufacturing process by reducing the amount of solvent contained in the adhesive, simply reducing the amount of solvent increases the viscosity of the adhesive and reduces processability. be. In order to reduce the amount of solvent, that is, to prevent the viscosity from increasing even if the solid content of the adhesive is increased, it is necessary to lower the molecular weight of components such as (meth)acrylic copolymers contained in the adhesive. There is a need to. On the other hand, the functions required for the adhesive layer include retention performance consisting of bulk cohesive force and heat resistance, and adhesiveness consisting of interfacial wettability and bulk fluidity. The molecular weight of components such as (meth)acrylic copolymers needed to be approximately 500,000 or more in order to satisfy these properties.
本発明は、分子量の低い（メタ）アクリル共重合体を用いながらも、保持性能及び接着性に優れる粘着剤層を有する粘着テープを提供することを目的とする。 An object of the present invention is to provide a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer having excellent retention performance and adhesiveness even though it uses a (meth)acrylic copolymer having a low molecular weight.
本開示１は、粘着剤層を有する粘着テープであって、上記粘着剤層は、（メタ）アクリル共重合体と架橋剤と粘着付与樹脂とを含む粘着剤の架橋生成物を含有し、上記架橋生成物の架橋点のアルカリ分解により得た（メタ）アクリル共重合体について示差屈折計ＲＩ検出によるＧＰＣ測定を行った際の、分子量５０００以上の領域における該（メタ）アクリル共重合体の重量平均分子量が８万以上５０万未満であり、ＳＵＳ板と貼り合わせた上記粘着テープについて、８０℃におけるせん断方向に１ｋｇ荷重を２４時間加える保持試験において該粘着テープが落下しない、かつ、ＳＵＳ板に対する該粘着テープの１８０°引きはがし粘着力が１５Ｎ／２５ｍｍ以上である粘着テープである。
本開示２は、粘着剤層を有する粘着テープであって、上記粘着剤層は、（メタ）アクリル共重合体と架橋剤と粘着付与樹脂とを含む粘着剤の架橋生成物を含有し、上記架橋生成物の架橋点のアルカリ分解により得た（メタ）アクリル共重合体について示差屈折計ＲＩ検出によるＧＰＣ測定を行った際の、分子量５０００以上の領域における該（メタ）アクリル共重合体の重量平均分子量が８万以上５０万未満であり、かつ、下記第一の構成、下記第二の構成、又は、下記第三の構成を満たす粘着テープである。
第一の構成：上記粘着剤は、上記（メタ）アクリル共重合体１００質量部に対して上記架橋剤を６質量部以上含み、かつ、上記粘着剤層のゲル分率が５質量％以上である
第二の構成：上記粘着剤は、上記（メタ）アクリル共重合体１００質量部に対して上記架橋剤を６質量部以上含み、上記粘着剤層のゲル分率が５質量％未満であり、かつ、上記粘着剤層のゾル成分について示差屈折計ＲＩ検出によるＧＰＣ測定を行った際の、分子量５０００以上の領域における該ゾル成分の重量平均分子量から、上記架橋生成物の架橋点のアルカリ分解により得た（メタ）アクリル共重合体について示差屈折計ＲＩ検出によるＧＰＣ測定を行った際の、分子量５０００以上の領域における該（メタ）アクリル共重合体の重量平均分子量を差し引いた値が８万以上である
第三の構成：上記粘着剤は、上記（メタ）アクリル共重合体１００質量部に対して上記架橋剤を０．１質量部以上６質量部未満含み、かつ、上記粘着剤層のゲル分率が３０質量％を超える
本開示３は、上記第一の構成を満たす、本開示２の粘着テープである。
本開示４は、上記第二の構成を満たす、本開示２の粘着テープである。
本開示５は、上記第三の構成を満たす、本開示２の粘着テープである。
本開示６は、上記粘着剤層は、下記第一の構成、下記第二の構成、又は、下記第三の構成を満たす本開示１記載の粘着テープである。
第一の構成：上記粘着剤は、上記（メタ）アクリル共重合体１００質量部に対して上記架橋剤を６質量部以上含み、かつ、上記粘着剤層のゲル分率が５質量％以上である
第二の構成：上記粘着剤は、上記（メタ）アクリル共重合体１００質量部に対して上記架橋剤を６質量部以上含み、上記粘着剤層のゲル分率が５質量％未満であり、かつ、上記粘着剤層のゾル成分について示差屈折計ＲＩ検出によるＧＰＣ測定を行った際の、分子量５０００以上の領域における該ゾル成分の重量平均分子量から、上記架橋生成物の架橋点のアルカリ分解により得た（メタ）アクリル共重合体について示差屈折計ＲＩ検出によるＧＰＣ測定を行った際の、分子量５０００以上の領域における該（メタ）アクリル共重合体の重量平均分子量を差し引いた値が８万以上である
第三の構成：前記粘着剤は、前記（メタ）アクリル共重合体１００質量部に対して前記架橋剤を０．１質量部以上６質量部未満含み、かつ、前記粘着剤層のゲル分率が３０質量％を超える
本開示７は、上記粘着剤層は、上記第一の構成として、上記粘着剤は、上記（メタ）アクリル共重合体１００質量部に対して上記架橋剤を６質量部以上含み、かつ、上記粘着剤層のゲル分率が５質量％以上３０質量％未満である構成を有するか、又は、上記第三の構成として、上記粘着剤は、上記（メタ）アクリル共重合体１００質量部に対して上記架橋剤を１．５質量部以上６質量部未満含み、かつ、上記粘着剤層のゲル分率が３０質量％を超える構成を有する本開示２又は６の粘着テープである。
本開示８は、上記粘着剤層は、上記第一の構成として、上記粘着剤は、上記（メタ）アクリル共重合体１００質量部に対して上記架橋剤を６質量部以上含み、かつ、上記粘着剤層のゲル分率が５質量％以上３０質量％未満である構成を有する本開示７の粘着テープである。
本開示９は、上記粘着剤層は、上記第三の構成として、上記粘着剤は、上記（メタ）アクリル共重合体１００質量部に対して上記架橋剤を１．５質量部以上６質量部未満含み、かつ、上記粘着剤層のゲル分率が３０質量％を超える構成を有する本開示７の粘着テープである。
本開示１０は、上記粘着剤層のゾル成分について示差屈折計ＲＩ検出によるＧＰＣ測定を行った際の、分子量５０００以上の領域における該ゾル成分の重量平均分子量が５万以上５０万以下である本開示１、２、３、４、５、６、７、８又は９の粘着テープである。
本開示１１は、上記架橋生成物の架橋点のアルカリ分解により得た（メタ）アクリル共重合体について示差屈折計ＲＩ検出によるＧＰＣ測定を行った際の、分子量５０００以上の領域における該（メタ）アクリル共重合体のピークトップ分子量が７万以上３０万以下である本開示１、２、３、４、５、６、７、８、９又は１０の粘着テープである。
本開示１２は、上記粘着剤は、水酸基を有する化合物を固形分中０．０３質量％以上含み、かつ、カルボキシ基を有する化合物を固形分中２質量％以上含む本開示１、２、３、４、５、６、７、８、９、１０又は１１の粘着テープである。
本開示１３は、上記（メタ）アクリル共重合体は、炭素数が６以上のアルキル基を有するモノマーに由来する構成単位を５０質量％以上有する本開示１、２、３、４、５、６、７、８、９、１０、１１又は１２の粘着テープである。
本開示１４は、上記粘着剤層は、ガラス転移温度が－１０℃以上３０℃以下である本開示１、２、３、４、５、６、７、８、９、１０、１１、１２又は１３の粘着テープである。
本開示１５は、上記粘着剤層は、８０℃における貯蔵弾性率Ｇ’（８０℃）が１．０×１０４Ｐａ以上である本開示１、２、３、４、５、６、７、８、９、１０、１１、１２、１３又は１４の粘着テープである。
本開示１６は、上記粘着剤層は、厚みが１０μｍ以上１００μｍ以下である本開示１、２、３、４、５、６、７、８、９、１０、１１、１２、１３、１４又は１５の粘着テープである。
本開示１７は、上記粘着テープは、基材を有し、上記基材は、ポリエステル樹脂フィルム又はポリプロピレン樹脂フィルムであり、かつ、上記基材の厚みが５μｍ以上２００μｍ以下である本開示１、２、３、４、５、６、７、８、９、１０、１１、１２、１３、１４、１５又は１６の粘着テープである。
本開示１８は、上記粘着テープは、基材を有し、上記基材の両面に上記粘着剤層を有する本開示１、２、３、４、５、６、７、８、９、１０、１１、１２、１３、１４、１５、１６又は１７の粘着テープである。
以下、本発明を詳述する。
なお、本開示１の粘着テープを「本発明１の粘着テープ」ともいい、本開示２の粘着テープを「本発明２の粘着テープ」ともいう。また、本発明１の粘着テープと本発明２の粘着テープとに共通する事項については、特に指定しないか、又は、「本発明の粘着テープ」として記載する。 The present disclosure 1 is an adhesive tape having an adhesive layer, the adhesive layer containing a crosslinked product of an adhesive containing a (meth)acrylic copolymer, a crosslinking agent, and a tackifying resin, The weight of the (meth)acrylic copolymer obtained by alkaline decomposition of the crosslinking points of the crosslinked product in the region of molecular weight 5000 or more when GPC measurement is performed using differential refractometer RI detection. The above-mentioned adhesive tape has an average molecular weight of 80,000 or more and is less than 500,000, and is bonded to a SUS plate.The adhesive tape does not fall in a holding test in which a 1 kg load is applied in the shear direction at 80°C for 24 hours, and the adhesive tape does not fall off against the SUS plate. The adhesive tape has a 180° peeling adhesive strength of 15 N/25 mm or more.
The present disclosure 2 is an adhesive tape having an adhesive layer, wherein the adhesive layer contains a crosslinked product of an adhesive containing a (meth)acrylic copolymer, a crosslinking agent, and a tackifying resin, The weight of the (meth)acrylic copolymer obtained by alkaline decomposition of the crosslinking points of the crosslinked product in the region of molecular weight 5000 or more when GPC measurement is performed using differential refractometer RI detection. The adhesive tape has an average molecular weight of 80,000 or more and less than 500,000, and satisfies the following first configuration, the following second configuration, or the following third configuration.
First configuration: The adhesive contains 6 parts by mass or more of the crosslinking agent based on 100 parts by mass of the (meth)acrylic copolymer, and the gel fraction of the adhesive layer is 5% by mass or more. A second configuration: the adhesive contains 6 parts by mass or more of the crosslinking agent based on 100 parts by mass of the (meth)acrylic copolymer, and the adhesive layer has a gel fraction of less than 5% by mass. , and from the weight average molecular weight of the sol component in the molecular weight region of 5,000 or more when performing GPC measurement using differential refractometer RI detection on the sol component of the adhesive layer, the alkali decomposition of the crosslinking point of the crosslinked product is determined. When the (meth)acrylic copolymer obtained was subjected to GPC measurement using differential refractometer RI detection, the value obtained by subtracting the weight average molecular weight of the (meth)acrylic copolymer in the molecular weight region of 5,000 or more was 80,000. The above third configuration: the adhesive contains 0.1 parts by mass or more and less than 6 parts by mass of the crosslinking agent based on 100 parts by mass of the (meth)acrylic copolymer, and the adhesive layer contains Present Disclosure 3, in which the gel fraction exceeds 30% by mass, is the adhesive tape of Present Disclosure 2 that satisfies the above first configuration.
The present disclosure 4 is the adhesive tape of the present disclosure 2 that satisfies the second configuration.
The present disclosure 5 is the adhesive tape of the present disclosure 2 that satisfies the third configuration.
The present disclosure 6 is the adhesive tape according to the present disclosure 1, in which the adhesive layer satisfies the following first configuration, the following second configuration, or the following third configuration.
First configuration: The adhesive contains 6 parts by mass or more of the crosslinking agent based on 100 parts by mass of the (meth)acrylic copolymer, and the gel fraction of the adhesive layer is 5% by mass or more. A second configuration: the adhesive contains 6 parts by mass or more of the crosslinking agent based on 100 parts by mass of the (meth)acrylic copolymer, and the adhesive layer has a gel fraction of less than 5% by mass. , and from the weight average molecular weight of the sol component in the molecular weight region of 5,000 or more when performing GPC measurement using differential refractometer RI detection on the sol component of the adhesive layer, the alkali decomposition of the crosslinking point of the crosslinked product is determined. When the (meth)acrylic copolymer obtained was subjected to GPC measurement using differential refractometer RI detection, the value obtained by subtracting the weight average molecular weight of the (meth)acrylic copolymer in the molecular weight region of 5,000 or more was 80,000. The above third configuration: the adhesive contains 0.1 parts by mass or more and less than 6 parts by mass of the crosslinking agent based on 100 parts by mass of the (meth)acrylic copolymer, and the adhesive layer contains In the present disclosure 7, in which the gel fraction exceeds 30% by mass, the adhesive layer has the first configuration, and the adhesive contains the crosslinking agent based on 100 parts by mass of the (meth)acrylic copolymer. 6 parts by mass or more, and the gel fraction of the adhesive layer is 5% by mass or more and less than 30% by mass, or as the third configuration, the adhesive has the above (meth) Present Disclosure 2 or 6, wherein the crosslinking agent is contained in 1.5 parts by mass or more and less than 6 parts by mass based on 100 parts by mass of the acrylic copolymer, and the adhesive layer has a gel fraction of more than 30% by mass. This is an adhesive tape.
The present disclosure 8 provides that the adhesive layer has the first configuration, wherein the adhesive contains 6 parts by mass or more of the crosslinking agent based on 100 parts by mass of the (meth)acrylic copolymer, and The adhesive tape of the present disclosure 7 has a configuration in which the adhesive layer has a gel fraction of 5% by mass or more and less than 30% by mass.
In the present disclosure 9, the adhesive layer has the third configuration, and the adhesive contains 1.5 parts by mass or more and 6 parts by mass of the crosslinking agent based on 100 parts by mass of the (meth)acrylic copolymer. The pressure-sensitive adhesive tape of the present disclosure 7 has a structure in which the gel fraction of the pressure-sensitive adhesive layer exceeds 30% by mass.
Present disclosure 10 is a book in which the weight average molecular weight of the sol component of the adhesive layer in a region of molecular weight 5000 or more is 50,000 or more and 500,000 or less when GPC measurement is performed using differential refractometer RI detection. The adhesive tape of Disclosure 1, 2, 3, 4, 5, 6, 7, 8 or 9.
This disclosure 11 discloses that the (meth)acrylic copolymer obtained by alkaline decomposition of the crosslinking point of the crosslinked product is subjected to GPC measurement using differential refractometer RI detection, and the (meth) The adhesive tape of the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, wherein the peak top molecular weight of the acrylic copolymer is 70,000 or more and 300,000 or less.
This disclosure 12 provides that the adhesive contains 0.03% by mass or more of a compound having a hydroxyl group in the solid content, and 2% or more by mass of the compound having a carboxy group in the solid content of the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or 11 adhesive tape.
Present disclosure 13 provides that the above-mentioned (meth)acrylic copolymer has 50% by mass or more of a structural unit derived from a monomer having an alkyl group having 6 or more carbon atoms. , 7, 8, 9, 10, 11 or 12 adhesive tape.
Present disclosure 14 is the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, or 13 adhesive tape.
The present disclosure 15 is the present disclosure 1, 2, 3, 4, 5, 6, 7, wherein the adhesive layer has a storage modulus G' (80 °C) of 1.0 × 10 4 Pa or more, No. 8, 9, 10, 11, 12, 13 or 14 adhesive tape.
This disclosure 16 provides that the adhesive layer has a thickness of 10 μm or more and 100 μm or less. This is an adhesive tape.
Present Disclosure 17 provides Present Disclosures 1 and 2, wherein the adhesive tape has a base material, the base material is a polyester resin film or a polypropylene resin film, and the thickness of the base material is 5 μm or more and 200 μm or less. , 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 or 16 adhesive tapes.
Present disclosure 18 is the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, wherein the adhesive tape has a base material, and the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, No. 11, 12, 13, 14, 15, 16 or 17 adhesive tape.
The present invention will be explained in detail below.
Note that the adhesive tape of the present disclosure 1 is also referred to as the "adhesive tape of the present invention 1", and the adhesive tape of the present disclosure 2 is also referred to as the "adhesive tape of the present invention 2". Further, matters common to the adhesive tape of the first invention and the adhesive tape of the second invention are not specified or are described as "the adhesive tape of the invention".
本発明者らは、粘着剤層の形成に特定の低い分子量を有する（メタ）アクリル共重合体を含む粘着剤を用いる場合であっても、該粘着剤層として特定の構成を有するものとすることにより、保持性能及び接着性に優れる粘着剤層を有する粘着テープを得ることができることを見出し、本発明を完成させるに至った。 The present inventors believe that even when an adhesive containing a (meth)acrylic copolymer having a specific low molecular weight is used to form an adhesive layer, the adhesive layer has a specific configuration. The inventors have discovered that, by doing so, it is possible to obtain an adhesive tape having an adhesive layer with excellent retention performance and adhesive properties, and have completed the present invention.
本発明の粘着テープは、粘着剤層を有する粘着テープである。
上記粘着剤層は、（メタ）アクリル共重合体と架橋剤と粘着付与樹脂とを含む粘着剤の架橋生成物を含有する。
なお、本明細書中において「（メタ）アクリル」は、アクリル又はメタクリルを意味する。 The adhesive tape of the present invention is an adhesive tape having an adhesive layer.
The adhesive layer contains a crosslinked adhesive product containing a (meth)acrylic copolymer, a crosslinking agent, and a tackifying resin.
In this specification, "(meth)acrylic" means acrylic or methacryl.
本発明の粘着テープにおいて上記粘着剤層は、上記架橋生成物の架橋点のアルカリ分解により得た（メタ）アクリル共重合体について示差屈折計ＲＩ検出によるＧＰＣ測定を行った際の、分子量５０００以上の領域における該（メタ）アクリル共重合体の重量平均分子量（以下、単に「アルカリ分解により得た（メタ）アクリル共重合体の重量平均分子量」ともいう）が８万以上５０万未満である。
上記アルカリ分解により得た（メタ）アクリル共重合体の重量平均分子量が８万以上であることにより、得られる粘着剤層におけるバルクの凝集力が大きくなり、該粘着剤層が耐熱性に優れるものとなる。上記アルカリ分解により得た（メタ）アクリル共重合体の重量平均分子量が５０万未満であることにより、上記粘着剤層を形成するために用いられる粘着剤の粘度を低くすることができ、加工性を向上させることができるとともに、製造プロセスにおいて排出されるＣＯ２の由来となる溶剤の量を低減することができる。上記アルカリ分解により得た（メタ）アクリル共重合体の重量平均分子量の好ましい下限は１０万、より好ましい下限は１５万であり、好ましい上限は４９万、より好ましい上限は４５万、更により好ましい上限は４０万である。
なお、本明細書中において、上記「アルカリ分解により得た（メタ）アクリル共重合体」は、上記粘着剤に含まれる（メタ）アクリル共重合体であってもよく、その他の化合物であってもよい。その他の化合物としては、例えば、上記粘着剤に含まれる（メタ）アクリル共重合体の構造の一部が、修飾及び／又は欠損されている（メタ）アクリル共重合体等が挙げられる。
また、上記架橋生成物の架橋点のアルカリ分解は、以下の方法により行う。
即ち、圧力容器に上記粘着剤層３００ｍｇ、エタノール６ｍＬ、６０％ＫＯＨ水溶液７ｍＬを加え、１６０℃のオーブンで６０時間加圧加水分解することにより、架橋生成物の架橋点をアルカリ分解し、（メタ）アクリル共重合体を得る。
また、上記架橋生成物の架橋点のアルカリ分解により得た（メタ）アクリル共重合体について示差屈折計ＲＩ検出によるＧＰＣ測定を行うときは、例えば、次の方法を採用することができる。
即ち、上記架橋生成物の架橋点のアルカリ分解により得た（メタ）アクリル共重合体について、ゲルパーミエーションクロマトグラフィー（ＧＰＣ）（Ｗａｔｅｒｓ社製、「２６９０　Ｓｅｐａｒａｔｉｏｎｓ　Ｍｏｄｅｌ」）による分析を行い、ポリスチレン換算による分子量分布を測定する。上記ＧＰＣは、以下の条件で行うことができる。
　溶離液：テトラヒドロフラン（ＴＨＦ）
　流量：０．４ｍＬ／ｍｉｎ
　検出器：示差屈折計ＲＩ
　カラム：ＬＦ－８０４（ＳＨＯＫＯ社製）
　カラム温度（測定温度）：４０℃
　注入量：２０μＬ In the adhesive tape of the present invention, the adhesive layer has a molecular weight of 5,000 or more when GPC measurement using differential refractometer RI detection is performed on a (meth)acrylic copolymer obtained by alkaline decomposition of the crosslinking points of the crosslinked product. The weight average molecular weight of the (meth)acrylic copolymer in the range (hereinafter also simply referred to as "the weight average molecular weight of the (meth)acrylic copolymer obtained by alkaline decomposition") is 80,000 or more and less than 500,000.
When the weight average molecular weight of the (meth)acrylic copolymer obtained by the above alkaline decomposition is 80,000 or more, the bulk cohesive force in the resulting adhesive layer is increased, and the adhesive layer has excellent heat resistance. becomes. Since the weight average molecular weight of the (meth)acrylic copolymer obtained by the alkali decomposition is less than 500,000, the viscosity of the adhesive used to form the adhesive layer can be lowered, and processability is improved. In addition, it is possible to reduce the amount of solvent that is the source of CO 2 emitted during the manufacturing process. The preferable lower limit of the weight average molecular weight of the (meth)acrylic copolymer obtained by the above alkaline decomposition is 100,000, the more preferable lower limit is 150,000, the preferable upper limit is 490,000, the more preferable upper limit is 450,000, and the even more preferable upper limit is is 400,000.
In addition, in this specification, the above-mentioned "(meth)acrylic copolymer obtained by alkaline decomposition" may be the (meth)acrylic copolymer contained in the above-mentioned adhesive, or may be any other compound. Good too. Examples of other compounds include (meth)acrylic copolymers in which part of the structure of the (meth)acrylic copolymer contained in the pressure-sensitive adhesive is modified and/or deleted.
Further, alkaline decomposition of the crosslinking points of the crosslinked product is performed by the following method.
That is, 300 mg of the above adhesive layer, 6 mL of ethanol, and 7 mL of 60% KOH aqueous solution were added to a pressure vessel, and the mixture was hydrolyzed under pressure in an oven at 160°C for 60 hours to alkali decompose the crosslinking points of the crosslinked product and convert it into (meth) ) Obtain an acrylic copolymer.
Further, when performing GPC measurement using differential refractometer RI detection on the (meth)acrylic copolymer obtained by alkaline decomposition of the crosslinking points of the crosslinked product, for example, the following method can be adopted.
That is, the (meth)acrylic copolymer obtained by alkaline decomposition of the crosslinking points of the crosslinked product was analyzed by gel permeation chromatography (GPC) (manufactured by Waters, "2690 Separations Model"), and the polystyrene equivalent Measure the molecular weight distribution by The above GPC can be performed under the following conditions.
Eluent: Tetrahydrofuran (THF)
Flow rate: 0.4mL/min
Detector: Differential refractometer RI
Column: LF-804 (manufactured by SHOKO)
Column temperature (measurement temperature): 40°C
Injection volume: 20μL
本発明の粘着テープにおいて上記粘着剤層は、上記架橋生成物の架橋点のアルカリ分解により得た（メタ）アクリル共重合体について示差屈折計ＲＩ検出によるＧＰＣ測定を行った際の、分子量５０００以上の領域における該（メタ）アクリル共重合体のピークトップ分子量（以下、単に「アルカリ分解により得た（メタ）アクリル共重合体のピークトップ分子量」ともいう）の好ましい下限が７万、好ましい上限が３０万である。
上記アルカリ分解により得た（メタ）アクリル共重合体のピークトップ分子量が７万以上であることにより、得られる粘着剤層におけるバルクの凝集力がより大きくなり、該粘着剤層が耐熱性により優れるものとなる。上記アルカリ分解により得た（メタ）アクリル共重合体のピークトップ分子量が３０万以下であることにより、上記粘着剤層を形成するために用いられる粘着剤の粘度をより低くすることができ、加工性をより向上させることができるとともに、製造プロセスにおいて排出されるＣＯ２の由来となる溶剤の量をより低減することができる。上記アルカリ分解により得た（メタ）アクリル共重合体のピークトップ分子量のより好ましい下限は８万、更に好ましい下限は１０万であり、より好ましい上限は２５万、更に好ましい上限は２３万である。
なお、本明細書において、「ピークトップ分子量」は、分子量分布曲線における最も高いピークにおける分子量を意味する。分子量分布曲線にショルダーが存在したりピークが２以上存在したりする場合であっても、上記ピークトップ分子量は、分子量分布曲線における最も高いピークにおける分子量を意味する。 In the adhesive tape of the present invention, the adhesive layer has a molecular weight of 5,000 or more when GPC measurement using differential refractometer RI detection is performed on a (meth)acrylic copolymer obtained by alkaline decomposition of the crosslinking points of the crosslinked product. The preferable lower limit of the peak top molecular weight of the (meth)acrylic copolymer in the region (hereinafter also simply referred to as "the peak top molecular weight of the (meth)acrylic copolymer obtained by alkaline decomposition") is 70,000, and the preferable upper limit is 70,000. It is 300,000.
Since the peak top molecular weight of the (meth)acrylic copolymer obtained by the above-mentioned alkaline decomposition is 70,000 or more, the bulk cohesive force in the resulting adhesive layer becomes larger, and the adhesive layer has better heat resistance. Become something. Since the peak top molecular weight of the (meth)acrylic copolymer obtained by the alkali decomposition is 300,000 or less, the viscosity of the adhesive used to form the adhesive layer can be lowered, and processing It is possible to further improve the properties and further reduce the amount of solvent, which is the source of CO 2 emitted during the manufacturing process. A more preferable lower limit of the peak top molecular weight of the (meth)acrylic copolymer obtained by the alkali decomposition is 80,000, an even more preferable lower limit is 100,000, a more preferable upper limit is 250,000, and an even more preferable upper limit is 230,000.
In addition, in this specification, "peak top molecular weight" means the molecular weight at the highest peak in a molecular weight distribution curve. Even if there is a shoulder or two or more peaks in the molecular weight distribution curve, the peak top molecular weight means the molecular weight at the highest peak in the molecular weight distribution curve.
本発明の粘着テープにおいて上記粘着剤層は、分子量分布を調整する観点から、上記架橋生成物の架橋点のアルカリ分解により得た（メタ）アクリル共重合体について示差屈折計ＲＩ検出によるＧＰＣ測定を行った際の、分子量５０００以上の領域における該（メタ）アクリル共重合体の多分散度（以下、単に「アルカリ分解により得た（メタ）アクリル共重合体の多分散度」ともいう）の好ましい下限は１．５万であり、好ましい上限は１０万、より好ましい上限は６万である。
なお、上記多分散度は、重量平均分子量（Ｍｗ）と数平均分子量（Ｍｎ）との比（Ｍｗ／Ｍｎ）を意味する。 In the pressure-sensitive adhesive layer of the present invention, from the viewpoint of adjusting the molecular weight distribution, the polydispersity of the (meth)acrylic copolymer obtained by alkaline decomposition of the crosslinking points of the crosslinked product in a molecular weight region of 5,000 or more when the (meth)acrylic copolymer is subjected to GPC measurement with RI detection using a differential refractometer (hereinafter also simply referred to as "polydispersity of the (meth)acrylic copolymer obtained by alkaline decomposition") is preferably 15,000 in lower limit, and preferably 100,000 in upper limit, more preferably 60,000 in upper limit.
The polydispersity refers to the ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn).
本発明の粘着テープにおいて上記粘着剤層は、上記粘着剤層のゾル成分について示差屈折計ＲＩ検出によるＧＰＣ測定を行った際の、分子量５０００以上の領域における該ゾル成分の重量平均分子量（以下、単に「ゾル成分の重量平均分子量」ともいう）の好ましい下限は５万、好ましい上限は５０万である。上記ゾル成分の重量平均分子量が５万以上であることにより、得られる粘着剤層におけるバルクの凝集力がより大きくなり、該粘着剤層が耐熱性や高温耐反発性により優れるものとなる。上記ゾル成分の重量平均分子量が５０万以下であることにより、上記粘着剤層を形成するために用いられる粘着剤の粘度をより低くすることができ、加工性をより向上させることができるとともに、製造プロセスにおいて排出されるＣＯ２の由来となる溶剤の量をより低減することができる。上記ゾル成分の重量平均分子量のより好ましい下限は７万、更に好ましい下限は１０万であり、より好ましい上限は４０万、更に好ましい上限は３０万である。
ここで、上記「ゾル成分」とは、上記粘着剤層から「ゲル成分」を除いた成分を意味する。なお、上記「ゲル成分」は、上記（メタ）アクリル共重合体、後述する粘着付与樹脂等が後述する架橋剤を介して架橋構造を構築している上記ゲル分率測定の処理でメッシュに残った流動性の低い成分であり、上記「ゾル成分」は、上記処理でゲル成分を除いた流動性の高い成分である。
上記粘着剤層のゾル成分は、例えば、上記粘着剤層をテトラヒドロフラン（ＴＨＦ）中に２３℃にて２４時間浸漬し、不溶解分を２００メッシュの金網で濾過して、ゲル成分を取り除くことで得ることができる。
上記粘着剤層のゾル成分について示差屈折計ＲＩ検出によるＧＰＣ測定を行うときは、例えば、次の方法を採用することができる。
即ち、上記粘着剤層のゾル成分について、ゲルパーミエーションクロマトグラフィー（ＧＰＣ）（Ｗａｔｅｒｓ社製、「２６９０　Ｓｅｐａｒａｔｉｏｎｓ　Ｍｏｄｅｌ」）による分析を行い、ポリスチレン換算による分子量分布を測定する。上記ＧＰＣは、以下の条件で行うことができる。
　溶離液：テトラヒドロフラン（ＴＨＦ）
　流量：０．４ｍＬ／ｍｉｎ
　検出器：示差屈折計ＲＩ
　カラム：ＬＦ－８０４（ＳＨＯＫＯ社製）
　カラム温度（測定温度）：４０℃
　注入量：２０μＬ In the adhesive tape of the present invention, the adhesive layer has a weight average molecular weight (hereinafter referred to as The preferable lower limit of the weight average molecular weight (also simply referred to as "weight average molecular weight of the sol component") is 50,000, and the preferable upper limit is 500,000. When the weight average molecular weight of the sol component is 50,000 or more, the bulk cohesive force in the resulting adhesive layer becomes larger, and the adhesive layer has better heat resistance and high-temperature repulsion resistance. When the weight average molecular weight of the sol component is 500,000 or less, the viscosity of the adhesive used to form the adhesive layer can be lowered, and processability can be further improved, The amount of solvent that is the source of CO 2 emitted during the manufacturing process can be further reduced. A more preferable lower limit of the weight average molecular weight of the sol component is 70,000, an even more preferable lower limit is 100,000, a more preferable upper limit is 400,000, and an even more preferable upper limit is 300,000.
Here, the above-mentioned "sol component" means a component obtained by removing the "gel component" from the above-mentioned adhesive layer. Note that the above-mentioned "gel component" remains in the mesh during the gel fraction measurement process in which the above-mentioned (meth)acrylic copolymer, tackifying resin, etc. described below construct a cross-linked structure via the cross-linking agent described later. The above-mentioned "sol component" is a component with high fluidity from which the gel component has been removed by the above treatment.
The sol component of the adhesive layer can be obtained by, for example, immersing the adhesive layer in tetrahydrofuran (THF) at 23°C for 24 hours and filtering the insoluble matter through a 200 mesh wire mesh to remove the gel component. Obtainable.
When performing GPC measurement using differential refractometer RI detection for the sol component of the adhesive layer, for example, the following method can be adopted.
That is, the sol component of the adhesive layer is analyzed by gel permeation chromatography (GPC) (manufactured by Waters, "2690 Separations Model") to measure the molecular weight distribution in terms of polystyrene. The above GPC can be performed under the following conditions.
Eluent: Tetrahydrofuran (THF)
Flow rate: 0.4mL/min
Detector: Differential refractometer RI
Column: LF-804 (manufactured by SHOKO)
Column temperature (measurement temperature): 40°C
Injection volume: 20μL
本発明の粘着テープにおいて上記粘着剤層は、上記粘着剤層のゾル成分について示差屈折計ＲＩ検出によるＧＰＣ測定を行った際の、分子量５０００以上の領域における該ゾル成分のピークトップ分子量（以下、単に「ゾル成分のピークトップ分子量」ともいう）の好ましい下限が３万、好ましい上限が３０万である。上記ゾル成分のピークトップ分子量が３万以上であることにより、得られる粘着剤層におけるバルクの凝集力がより大きくなり、該粘着剤層が耐熱性により優れるものとなる。上記ゾル成分のピークトップ分子量が３０万以下であることにより、上記粘着剤層を形成するために用いられる粘着剤の粘度をより低くすることができ、加工性をより向上させることができるとともに、製造プロセスにおいて排出されるＣＯ２の由来となる溶剤の量をより低減することができる。上記ゾル成分のピークトップ分子量のより好ましい下限は７万、更に好ましい下限は８万であり、より好ましい上限は２５万、更に好ましい上限は２３万である。 In the adhesive tape of the present invention, the adhesive layer has a peak top molecular weight (hereinafter referred to as (also simply referred to as "peak top molecular weight of the sol component") has a preferable lower limit of 30,000, and a preferable upper limit of 300,000. When the peak top molecular weight of the above-mentioned sol component is 30,000 or more, the bulk cohesive force in the resulting adhesive layer becomes larger, and the adhesive layer has better heat resistance. By setting the peak top molecular weight of the sol component to 300,000 or less, the viscosity of the adhesive used to form the adhesive layer can be lowered, and processability can be further improved, The amount of solvent that is the source of CO 2 emitted during the manufacturing process can be further reduced. A more preferable lower limit of the peak top molecular weight of the sol component is 70,000, an even more preferable lower limit is 80,000, a more preferable upper limit is 250,000, and an even more preferable upper limit is 230,000.
本発明１の粘着テープは、ＳＵＳ板と貼り合わせた後、８０℃においてせん断方向に１ｋｇ荷重を２４時間加える保持試験を行った際に、落下しない。上述したような保持試験の結果を示す該粘着テープは、耐熱性に優れるものとなり、例えば、電子デバイスに使用される部材に対する固定が良好となる。上記保持試験の結果としては、１ｍｍ以上のズレがないことが好ましく、０．５ｍｍ以上のズレがないことがより好ましい。
また、本発明２の粘着テープは、ＳＵＳ板と貼り合わせた後、８０℃においてせん断方向に１ｋｇ荷重を２４時間加える保持試験を行った際に、落下しないことが好ましい。上述したような保持試験の結果を示す該粘着テープは、耐熱性により優れるものとなり、例えば、電子デバイスに使用される部材に対する固定がより良好となる。上記保持試験の結果としては、１ｍｍ以上のズレがないことがより好ましく、０．５ｍｍ以上のズレがないことが更に好ましい。
上記保持試験は、以下の方法により行うことができる。また、上記保持試験の方法を示す模式図を図１に示す。
即ち、まず、粘着テープ１を２５ｍｍ幅の短冊状に裁断した後、ＳＵＳ板２に、２ｋｇのゴムローラーを３００ｍｍ／ｍｉｎの速度で一往復させることで貼り合わせる。次いで、接着面積が２５ｍｍ×２５ｍｍとなるように、粘着テープ１に切り込みを入れる。その後、２３℃で２０分間静置してから、８０℃のオーブンに入れ、更に１５分間加熱した後に、８０℃に保持しながら、図１に示すように１ｋｇの重り３を用いて、１ｋｇの荷重をせん断方向に加える。粘着テープの落下の有無を確認し、２４時間経過しても落下しなかった場合は、切り込み位置からの移動量（ズレ）をスケールルーペで測定する。 The adhesive tape of the present invention 1 does not fall when a holding test is performed in which a 1 kg load is applied in the shear direction at 80° C. for 24 hours after being bonded to a SUS plate. The adhesive tape that shows the results of the above-mentioned retention test has excellent heat resistance, and can be well fixed to members used in electronic devices, for example. As a result of the above-mentioned retention test, it is preferable that there is no deviation of 1 mm or more, and it is more preferable that there is no deviation of 0.5 mm or more.
Further, it is preferable that the adhesive tape of the second aspect of the present invention does not fall when subjected to a holding test in which a 1 kg load is applied in the shear direction at 80° C. for 24 hours after being bonded to a SUS plate. The adhesive tape exhibiting the results of the above-mentioned retention test has better heat resistance, and can be better fixed to members used in electronic devices, for example. As a result of the above retention test, it is more preferable that there is no deviation of 1 mm or more, and even more preferably that there is no deviation of 0.5 mm or more.
The above retention test can be performed by the following method. Moreover, a schematic diagram showing the method of the above-mentioned retention test is shown in FIG.
That is, first, the adhesive tape 1 is cut into strips with a width of 25 mm, and then bonded to the SUS board 2 by moving a 2 kg rubber roller back and forth at a speed of 300 mm/min. Next, a cut is made in the adhesive tape 1 so that the adhesive area is 25 mm x 25 mm. After that, it was left to stand at 23°C for 20 minutes, then placed in an oven at 80°C, and heated for another 15 minutes. Apply load in the shear direction. Check to see if the adhesive tape has fallen, and if it has not fallen after 24 hours, measure the amount of movement (displacement) from the cut position using a scale loupe.
本発明１の粘着テープは、ＳＵＳ板に対する該粘着テープの１８０°引きはがし粘着力が１５Ｎ／２５ｍｍ以上である。具体的には、ＳＵＳ板と貼り合わせた後、ＪＩＳ　Ｚ０２３７に準拠して、２３℃、剥離速度３００ｍｍ／ｍｉｎの条件で１８０°方向の引張試験を行った際の１８０°引きはがし粘着力が１５Ｎ／２５ｍｍ以上である。上記１８０°引きはがし粘着力が１５Ｎ／２５ｍｍ以上であることにより、粘着テープとして充分な接着性を有することができ、例えば、電子デバイスに使用される部材に対する固定が良好となる。上記１８０°引きはがし粘着力は、１８Ｎ／２５ｍｍ以上であることが好ましく、２０Ｎ／２５ｍｍ以上であることがより好ましい。
また、本発明２の粘着テープは、ＳＵＳ板に対する該粘着テープの１８０°引きはがし粘着力が１５Ｎ／２５ｍｍ以上であることが好ましい。具体的には、ＳＵＳ板と貼り合わせた後、ＪＩＳ　Ｚ０２３７に準拠して、２３℃、剥離速度３００ｍｍ／ｍｉｎの条件で１８０°方向の引張試験を行った際の１８０°引きはがし粘着力が１５Ｎ／２５ｍｍ以上であることが好ましい。上記１８０°引きはがし粘着力が１５Ｎ／２５ｍｍ以上であることにより、粘着テープとしてより充分な接着性を有することができ、例えば、電子デバイスに使用される部材に対する固定がより良好となる。上記１８０°引きはがし粘着力は、１８Ｎ／２５ｍｍ以上であることがより好ましく、２０Ｎ／２５ｍｍ以上であることが更に好ましい。
上記１８０°引きはがし粘着力は、以下の方法により測定することができる。
即ち、まず、粘着テープを２５ｍｍ幅の短冊状に裁断した後、ＳＵＳ板に、２ｋｇのゴムローラーを３００ｍｍ／ｍｉｎの速度で一往復させることで貼り合わせる。次いで、温度２３℃、相対湿度５０％にて２０分間静置することにより試験片を得る。得られた試験片について、引張試験機を用いてＪＩＳ　Ｚ０２３７に準拠して、２３℃、剥離速度３００ｍｍ／ｍｉｎ、剥離角度１８０°の条件で引張試験を行うことにより、上記１８０°引きはがし粘着力を測定することができる。 The adhesive tape of the present invention 1 has a 180° peeling adhesive strength of 15 N/25 mm or more to an SUS board. Specifically, after bonding with a SUS plate, a 180° peeling adhesive force was 15N when a tensile test was performed in a 180° direction at 23°C and a peeling speed of 300 mm/min in accordance with JIS Z0237. /25mm or more. When the above-mentioned 180° peeling adhesive force is 15 N/25 mm or more, it can have sufficient adhesiveness as an adhesive tape, and can be well fixed to members used in electronic devices, for example. The 180° peeling adhesive force is preferably 18 N/25 mm or more, more preferably 20 N/25 mm or more.
Moreover, it is preferable that the adhesive tape of the present invention 2 has a 180° peeling adhesive strength of 15 N/25 mm or more to an SUS board. Specifically, after bonding with a SUS plate, a 180° peeling adhesive force was 15N when a tensile test was performed in a 180° direction at 23°C and a peeling speed of 300 mm/min in accordance with JIS Z0237. /25 mm or more is preferable. By having the above-mentioned 180° peeling adhesive force of 15 N/25 mm or more, the adhesive tape can have more sufficient adhesive properties, and can be better fixed to members used in electronic devices, for example. The 180° peeling adhesive force is more preferably 18 N/25 mm or more, and even more preferably 20 N/25 mm or more.
The above 180° peeling adhesive strength can be measured by the following method.
That is, first, an adhesive tape is cut into strips with a width of 25 mm, and then bonded to an SUS plate by moving a 2 kg rubber roller back and forth at a speed of 300 mm/min. Next, a test piece is obtained by allowing it to stand for 20 minutes at a temperature of 23° C. and a relative humidity of 50%. The obtained test piece was subjected to a tensile test using a tensile testing machine in accordance with JIS Z0237 under the conditions of 23°C, peeling speed of 300 mm/min, and peeling angle of 180°, and the above 180° peeling adhesive strength was determined. can be measured.
本発明２の粘着テープにおいて、上記粘着剤層は、下記第一の構成、下記第二の構成、又は、下記第三の構成を満たす。また、本発明１の粘着テープにおいて、上記粘着剤層は、下記第一の構成、下記第二の構成、又は、下記第三の構成を満たすことが好ましい。
第一の構成：上記粘着剤は、上記（メタ）アクリル共重合体１００質量部に対して上記架橋剤を６質量部以上含み、かつ、上記粘着剤層のゲル分率が５質量％以上である
第二の構成：上記粘着剤は、上記（メタ）アクリル共重合体１００質量部に対して上記架橋剤を６質量部以上含み、上記粘着剤層のゲル分率が５質量％未満であり、かつ、上記粘着剤層のゾル成分について示差屈折計ＲＩ検出によるＧＰＣ測定を行った際の、分子量５０００以上の領域における該ゾル成分の重量平均分子量から、上記架橋生成物の架橋点のアルカリ分解により得た（メタ）アクリル共重合体について示差屈折計ＲＩ検出によるＧＰＣ測定を行った際の、分子量５０００以上の領域における該（メタ）アクリル共重合体の重量平均分子量を差し引いた値が８万以上である
第三の構成：上記粘着剤は、上記（メタ）アクリル共重合体１００質量部に対して上記架橋剤を０．１質量部以上６質量部未満含み、かつ、上記粘着剤層のゲル分率が３０質量％を超える
本発明２の粘着テープにおいて、上記粘着剤層が上記第一の構成、上記第二の構成、又は、上記第三の構成を満たすことにより、得られる粘着剤層が保持性能及び接着性に優れるものとなる。また、本発明１の粘着テープにおいて、上記粘着剤層が上記第一の構成、上記第二の構成、又は、上記第三の構成を満たすことにより、得られる粘着剤層が保持性能及び接着性により優れるものとなる。 In the adhesive tape of the second aspect of the invention, the adhesive layer satisfies the following first configuration, the following second configuration, or the following third configuration. Further, in the adhesive tape of the present invention 1, the adhesive layer preferably satisfies the following first configuration, the following second configuration, or the following third configuration.
First configuration: The adhesive contains 6 parts by mass or more of the crosslinking agent based on 100 parts by mass of the (meth)acrylic copolymer, and the gel fraction of the adhesive layer is 5% by mass or more. A second configuration: the adhesive contains 6 parts by mass or more of the crosslinking agent based on 100 parts by mass of the (meth)acrylic copolymer, and the adhesive layer has a gel fraction of less than 5% by mass. , and from the weight average molecular weight of the sol component in the molecular weight region of 5,000 or more when performing GPC measurement using differential refractometer RI detection on the sol component of the adhesive layer, the alkali decomposition of the crosslinking point of the crosslinked product is determined. When the (meth)acrylic copolymer obtained was subjected to GPC measurement using differential refractometer RI detection, the value obtained by subtracting the weight average molecular weight of the (meth)acrylic copolymer in the molecular weight region of 5,000 or more was 80,000. The above third configuration: the adhesive contains 0.1 parts by mass or more and less than 6 parts by mass of the crosslinking agent based on 100 parts by mass of the (meth)acrylic copolymer, and the adhesive layer contains In the adhesive tape of the present invention 2 having a gel fraction of more than 30% by mass, the adhesive layer is obtained by satisfying the first configuration, the second configuration, or the third configuration. The layer has excellent retention performance and adhesion. Further, in the adhesive tape of the present invention 1, the adhesive layer satisfies the first configuration, the second configuration, or the third configuration, so that the resulting adhesive layer has good retention performance and adhesive properties. It becomes better.
上記第一の構成において、上記粘着剤が上記（メタ）アクリル共重合体１００質量部に対して上記架橋剤を６質量部以上有し、かつ、上記粘着剤層のゲル分率が５質量％以上であれば、得られる粘着剤層におけるバルクの凝集力が大きくなり、該粘着剤層が耐熱性に優れるものとなる。上記（メタ）アクリル共重合体の分子量が小さく、ゲル分率が低い値でも、架橋剤部数が多ければ、ゾル成分内での架橋及び高分子量化が進んでいると見なせるためである。上記第一の構成において、上記粘着剤層のゲル分率は１０質量％以上であることが好ましく、１５質量％以上であることがより好ましい。
なお、上記第一の構成、上記第二の構成、及び、上記第三の構成における上記粘着剤層のゲル分率の測定には、例えば、次の方法を採用することができる。
即ち、まず、上記粘着剤層をＷ１（ｇ）採取し、採取した上記粘着剤層を酢酸エチル中に２３℃にて２４時間浸漬し、不溶解分を２００メッシュの金網で濾過する。この金網上の残渣を１１０℃にて加熱乾燥し、得られた乾燥残渣の質量Ｗ２（ｇ）を測定する。得られたＷ１及びＷ２から、下記式（Ｉ）によりゲル分率（架橋度）を算出する。
　ゲル分率（質量％）＝１００×Ｗ２／Ｗ１　（Ｉ） In the first configuration, the adhesive contains 6 parts by mass or more of the crosslinking agent based on 100 parts by mass of the (meth)acrylic copolymer, and the gel fraction of the adhesive layer is 5% by mass. If it is above, the bulk cohesive force in the resulting adhesive layer will be large, and the adhesive layer will have excellent heat resistance. This is because even if the molecular weight of the (meth)acrylic copolymer is small and the gel fraction is low, if the number of crosslinking agent parts is large, it can be considered that crosslinking and polymerization within the sol component are progressing. In the first configuration, the gel fraction of the pressure-sensitive adhesive layer is preferably 10% by mass or more, more preferably 15% by mass or more.
Note that the following method can be adopted, for example, to measure the gel fraction of the adhesive layer in the first configuration, the second configuration, and the third configuration.
That is, first, W 1 (g) of the adhesive layer was collected, the collected adhesive layer was immersed in ethyl acetate at 23°C for 24 hours, and the insoluble matter was filtered through a 200-mesh wire mesh. The residue on the wire mesh is heated and dried at 110° C., and the mass W 2 (g) of the obtained dried residue is measured. From the obtained W 1 and W 2 , the gel fraction (crosslinking degree) is calculated using the following formula (I).
Gel fraction (mass%) = 100 x W 2 /W 1 (I)
上記第一の構成において、上記粘着剤層のゲル分率は、３０質量％未満であることが好ましい。上記第一の構成において、上記粘着剤層のゲル分率が３０質量％未満であることにより、粘着剤層の弾性率の上昇によるバルクの流動性の低下を抑制し、該粘着剤層が界面の濡れ性を大きく低下させることなく接着性により優れるものとなる。上記第一の構成において、上記粘着剤層のゲル分率は、２８質量％以下であることがより好ましい。 In the first configuration, the adhesive layer preferably has a gel fraction of less than 30% by mass. In the first configuration, the adhesive layer has a gel fraction of less than 30% by mass, thereby suppressing a decrease in bulk fluidity due to an increase in the elastic modulus of the adhesive layer, and allowing the adhesive layer to This results in better adhesion without significantly reducing the wettability of the adhesive. In the first configuration, the adhesive layer preferably has a gel fraction of 28% by mass or less.
上記第一の構成において、上記粘着剤における上記（メタ）アクリル共重合体１００質量部に対する上記架橋剤の含有量は、１２質量部以下であることが好ましい。上記第一の構成において、上記粘着剤における上記架橋剤の含有量が１２質量部以下であることにより、粘着剤層の弾性率の上昇によるバルクの流動性の低下を抑制し、該粘着剤層が界面の濡れ性を大きく低下させることなく接着性により優れるものとなる。上記第一の構成において、上記粘着剤における上記架橋剤の含有量は、１０質量部以下であることがより好ましい。 In the first configuration, the content of the crosslinking agent in the pressure-sensitive adhesive based on 100 parts by mass of the (meth)acrylic copolymer is preferably 12 parts by mass or less. In the first configuration, the content of the crosslinking agent in the adhesive is 12 parts by mass or less, thereby suppressing a decrease in bulk fluidity due to an increase in the elastic modulus of the adhesive layer. However, the adhesion is improved without significantly reducing the wettability of the interface. In the first configuration, the content of the crosslinking agent in the pressure-sensitive adhesive is more preferably 10 parts by mass or less.
上記第二の構成において、上記粘着剤層のゾル成分について示差屈折計ＲＩ検出によるＧＰＣ測定を行った際の、分子量５０００以上の領域における該ゾル成分の重量平均分子量から、上記アルカリ分解により得た（メタ）アクリル共重合体の重量平均分子量を差し引いた値が８万以上である。これにより、上記粘着剤層のゲル分率が小さくてもゾル成分内でのポリマーの架橋が進んで分子量が大きくなり、上記粘着剤層におけるバルクの凝集力が高い状態となる。上記第二の構成において、上記粘着剤層のゲル分率の好ましい下限は０．１質量％、より好ましい下限は１質量％である。また、上記第二の構成において、上記ゾル成分の重量平均分子量から上記アルカリ分解により得た（メタ）アクリル共重合体の重量平均分子量を差し引いた値の好ましい下限は１０万、より好ましい下限は１２万である。 In the second configuration, the weight average molecular weight of the sol component of the adhesive layer in the region of molecular weight 5,000 or more when GPC measurement is performed using differential refractometer RI detection, the sol component obtained by the alkaline decomposition is The value obtained by subtracting the weight average molecular weight of the (meth)acrylic copolymer is 80,000 or more. As a result, even if the gel fraction of the pressure-sensitive adhesive layer is small, crosslinking of the polymer within the sol component proceeds and the molecular weight increases, resulting in a state where the bulk cohesive force in the pressure-sensitive adhesive layer is high. In the second configuration, the preferable lower limit of the gel fraction of the pressure-sensitive adhesive layer is 0.1% by mass, and the more preferable lower limit is 1% by mass. Further, in the second configuration, the preferable lower limit of the value obtained by subtracting the weight average molecular weight of the (meth)acrylic copolymer obtained by the alkaline decomposition from the weight average molecular weight of the sol component is 100,000, and the more preferable lower limit is 12 Ten thousand.
上記第三の構成において、上記粘着剤層のゲル分率が３０質量％を超えることにより、上記粘着剤層におけるバルクの凝集力が大きくなり、該粘着剤層が耐熱性に優れるものとなる。上記第三の構成において、上記粘着剤層のゲル分率は３１質量％以上であることが好ましく、３５質量％以上であることがより好ましく、４０質量％以上であることが更に好ましく、４５質量％以上であることが更により好ましい。
また、上記第三の構成において、上記粘着剤層のゲル分率は７０質量％以下であることが好ましい。上記第三の構成において、上記粘着剤層のゲル分率が７０質量％以下であることにより、上記粘着剤層におけるバルクの流動性の低下を抑制し、該粘着剤層が界面の濡れ性を大きく低下させることなく接着性により優れるものとなる。上記第三の構成において、上記粘着剤層のゲル分率は６５質量％以下であることがより好ましく、６０質量％以下であることが更に好ましい。
また、上記第三の構成において、上記粘着剤における上記（メタ）アクリル共重合体１００質量部に対する上記架橋剤の含有量は０．１質量部以上であることが好ましい。上記第三の構成において、上記粘着剤における上記架橋剤の含有量が０．１質量部以上であることにより、得られる粘着剤層のゲル分率が上がりやすく、バルクの凝集力がより大きくなる。上記第三の構成において、上記粘着剤における上記架橋剤の含有量は１．５質量部以上であることがより好ましく、２質量部以上であることが更に好ましい。 In the third configuration, when the gel fraction of the adhesive layer exceeds 30% by mass, the bulk cohesive force in the adhesive layer increases, and the adhesive layer has excellent heat resistance. In the third configuration, the gel fraction of the adhesive layer is preferably 31% by mass or more, more preferably 35% by mass or more, even more preferably 40% by mass or more, and 45% by mass. % or more is even more preferable.
Further, in the third configuration, the adhesive layer preferably has a gel fraction of 70% by mass or less. In the third configuration, the gel fraction of the adhesive layer is 70% by mass or less, thereby suppressing a decrease in bulk fluidity in the adhesive layer and improving the wettability of the interface. The adhesive properties are improved without significantly decreasing the adhesive properties. In the third configuration, the gel fraction of the pressure-sensitive adhesive layer is more preferably 65% by mass or less, and even more preferably 60% by mass or less.
Furthermore, in the third configuration, the content of the crosslinking agent in the pressure-sensitive adhesive based on 100 parts by mass of the (meth)acrylic copolymer is preferably 0.1 part by mass or more. In the third configuration, when the content of the crosslinking agent in the adhesive is 0.1 parts by mass or more, the gel fraction of the resulting adhesive layer tends to increase, and the bulk cohesive force becomes larger. . In the third configuration, the content of the crosslinking agent in the pressure-sensitive adhesive is more preferably 1.5 parts by mass or more, and even more preferably 2 parts by mass or more.
上記粘着剤層は、上記第一の構成として、上記粘着剤は、上記（メタ）アクリル共重合体１００質量部に対して上記架橋剤を６質量部以上含み、かつ、上記粘着剤層のゲル分率が５質量％以上３０質量％未満である構成を有するか、又は、上記第三の構成として、上記粘着剤は、上記（メタ）アクリル共重合体１００質量部に対して上記架橋剤を１．５質量部以上６質量部未満含み、かつ、上記粘着剤層のゲル分率が３０質量％を超える構成を有することが好ましい。 The adhesive layer has the first configuration, wherein the adhesive contains 6 parts by mass or more of the crosslinking agent based on 100 parts by mass of the (meth)acrylic copolymer, and the adhesive layer contains a gel of the adhesive layer. The adhesive has a composition in which the fraction is 5% by mass or more and less than 30% by mass, or as the third composition, the adhesive contains the crosslinking agent based on 100 parts by mass of the (meth)acrylic copolymer. It is preferable that the pressure-sensitive adhesive layer contains 1.5 parts by mass or more and less than 6 parts by mass, and the gel fraction of the pressure-sensitive adhesive layer exceeds 30% by mass.
上記粘着剤層について、上記アルカリ分解により得た（メタ）アクリル共重合体の重量平均分子量、ピークトップ分子量、及び、多分散度や、上記ゾル成分の重量平均分子量、及び、ピークトップ分子量や、上記ゾル成分の重量平均分子量から上記アルカリ分解により得た（メタ）アクリル共重合体の重量平均分子量を差し引いた値を上述した範囲に調整する方法は特に限定されない。具体的には例えば、上記粘着剤に含まれる（メタ）アクリル共重合体として、リビングラジカル重合、フリーラジカル重合等の重合方法により得られた（メタ）アクリル共重合体を用いる方法が挙げられる。なかでも、反応時間の短縮やコストを抑える観点からは、フリーラジカル重合により得られた（メタ）アクリル共重合体を用いる方法が好ましい。また、架橋点を均一に導入する観点からは、リビングラジカル重合が好ましい。架橋点を均一に導入すると、得られる粘着剤層が均一な架橋構造となり、バルクの凝集力が大きくなって、耐クリープ性が向上する。一方、バルクの凝集力が大きくなりすぎると、粘着剤層の柔軟性が損なわれ、界面に対する接着力が低下する。
また、上記重合方法により得られる（メタ）アクリル共重合体の重量平均分子量を制御することにより、上記アルカリ分解により得た（メタ）アクリル共重合体の、重量平均分子量及びピークトップ分子量を調整することができる。 Regarding the adhesive layer, the weight average molecular weight, peak top molecular weight, and polydispersity of the (meth)acrylic copolymer obtained by the above alkaline decomposition, the weight average molecular weight and peak top molecular weight of the sol component, The method for adjusting the value obtained by subtracting the weight average molecular weight of the (meth)acrylic copolymer obtained by the alkali decomposition from the weight average molecular weight of the sol component to the above range is not particularly limited. Specifically, for example, as the (meth)acrylic copolymer contained in the pressure-sensitive adhesive, a method using a (meth)acrylic copolymer obtained by a polymerization method such as living radical polymerization or free radical polymerization may be mentioned. Among these, from the viewpoint of reducing reaction time and cost, a method using a (meth)acrylic copolymer obtained by free radical polymerization is preferred. Furthermore, living radical polymerization is preferred from the viewpoint of uniformly introducing crosslinking points. When crosslinking points are uniformly introduced, the resulting pressure-sensitive adhesive layer has a uniform crosslinked structure, which increases bulk cohesive force and improves creep resistance. On the other hand, if the bulk cohesive force becomes too large, the flexibility of the adhesive layer will be impaired and the adhesive force to the interface will be reduced.
Furthermore, by controlling the weight average molecular weight of the (meth)acrylic copolymer obtained by the above polymerization method, the weight average molecular weight and peak top molecular weight of the (meth)acrylic copolymer obtained by the above alkaline decomposition can be adjusted. be able to.
上記重合方法により得られた（メタ）アクリル共重合体のなかでも重合温度及びモノマー混合物の濃度を一定に保つような比較的穏やかな重合条件により得られた（メタ）アクリル共重合体を用いることが好ましい。これにより、上記（メタ）アクリル共重合体の組成をより均一にしたり、上記アルカリ分解により得た（メタ）アクリル共重合体の多分散度を小さくしたりすることができ、上記粘着剤層のゾル成分の分子量分布を調整しやすくなる。このような比較的穏やかな重合条件となる重合方法としては、例えば、フリーラジカル定温重合を行う方法、フリーラジカル沸点重合のなかでも反応器内にモノマー混合物の半量と重合開始剤とを投入して重合を開始させた後でモノマー混合物の残り半量を滴下又は一括投入する方法等が挙げられる。 Among the (meth)acrylic copolymers obtained by the above polymerization method, use a (meth)acrylic copolymer obtained under relatively mild polymerization conditions such as keeping the polymerization temperature and monomer mixture concentration constant. is preferred. This makes it possible to make the composition of the above-mentioned (meth)acrylic copolymer more uniform and to reduce the polydispersity of the (meth)acrylic copolymer obtained by the above-mentioned alkaline decomposition, so that the pressure-sensitive adhesive layer can be It becomes easier to adjust the molecular weight distribution of the sol components. Polymerization methods that require relatively mild polymerization conditions include, for example, free radical constant temperature polymerization, and free radical boiling point polymerization in which half of the monomer mixture and a polymerization initiator are charged into the reactor. Examples include a method in which the remaining half of the monomer mixture is added dropwise or all at once after initiation of polymerization.
上記重合方法では、反応を２時間から１０時間で行うことが好ましい。重合時間を適切に調整しないと、フリーラジカル重合では、架橋性官能基含有モノマーの反応速度が速いためポリマー鎖の架橋点の導入が不均一になったり、残存モノマー量が多く残ったりして耐クリープ性が低下する。
上記重合方法における重合反応時間の好ましい下限は２時間、好ましい上限は１０時間である。上記重合反応時間がこの範囲であることにより、上記アルカリ分解により得た（メタ）アクリル共重合体の重量平均分子量等を上述した範囲に調整しやすくなる。上記重合反応時間のより好ましい下限は３時間、より好ましい上限は８時間である。 In the above polymerization method, the reaction is preferably carried out for 2 to 10 hours. If the polymerization time is not appropriately adjusted, the free radical polymerization causes the crosslinking points of the polymer chain to be introduced non-uniformly due to the high reaction rate of the crosslinkable functional group-containing monomer, or causes a large amount of residual monomer to remain, resulting in a decrease in creep resistance.
The polymerization reaction time in the polymerization method is preferably 2 hours at the lower limit and 10 hours at the upper limit. By setting the polymerization reaction time in this range, it becomes easier to adjust the weight average molecular weight of the (meth)acrylic copolymer obtained by the alkaline decomposition to the above-mentioned range. The polymerization reaction time is more preferably 3 hours at the lower limit and 8 hours at the upper limit.
上記重合方法に用いられる重合開始剤として、例えば、アゾ化合物、有機過酸化物等が挙げられる。
上記アゾ化合物としては、例えば、２，２’－アゾビス（イソブチロニトリル）、２，２’－アゾビス（２－メチルブチロニトリル）、２，２’－アゾビス（２，４－ジメチルバレロニトリル）、２，２’－アゾビス（４－メトキシ－２，４－ジメチルバレロニトリル）、１，１－アゾビス（シクロヘキサン－１－カルボニトリル）、１－（（１－シアノ－１－メチルエチル）アゾ）ホルムアミド、４，４’－アゾビス（４－シアノバレリアン酸）、ジメチル－２，２’－アゾビス（２－メチルプロピオネート）、ジメチル－１，１’－アゾビス（１－シクロヘキサンカルボキシレート）、２，２’－アゾビス（２－メチル－Ｎ－（１，１’－ビス（ヒドロキシメチル）－２－ヒドロキシエチル）プロピオンアミド）、２，２’－アゾビス（２－メチル－Ｎ－（２－ヒドロキシエチル）プロピオンアミド）、２，２’－アゾビス（Ｎ－（２－プロペニル）－２－メチルプロピオンアミド）、２，２’－アゾビス（Ｎ－ブチル－２－メチルプロピオンアミド）、２，２’－アゾビス（Ｎ－シクロヘキシル－２－メチルプロピオンアミド）、２，２’－アゾビス（２－（２－イミダゾリン－２－イル）プロパン）二塩酸塩、２，２’－アゾビス（２－（１－（２－ヒドロキシエチル）－２－イミダゾリン－２－イル）プロパン）二塩酸塩、２，２’－アゾビス（２－（２－イミダゾリン－２－イル）プロパン）、２，２’－アゾビス（２－アミジノプロパン）二塩酸塩、２，２’－アゾビス（Ｎ－（２－カルボキシエチル）－２－メチルプロピオンアミジン）四水和物、２，２’－アゾビス（１－イミノ－１－ピロリジノ－２－メチルプロパン）二塩酸塩、２，２’－アゾビス（２，４，４－トリメチルペンタン）等が挙げられる。これらのアゾ化合物は、単独で用いられてもよいし、２種以上が組み合わせて用いられてもよい。
上記有機過酸化物として、例えば、１，１－ビス（ｔ－ヘキシルパーオキシ）－３，３，５－トリメチルシクロヘキサン、ｔ－ヘキシルパーオキシピバレート、ｔ－ブチルパーオキシピバレート、２，５－ジメチル－２，５－ビス（２－エチルヘキサノイルパーオキシ）ヘキサン、ｔ－ヘキシルパーオキシ－２－エチルヘキサノエート、ｔ－ブチルパーオキシ－２－エチルヘキサノエート、ｔ－ブチルパーオキシイソブチレート、ｔ－ブチルパーオキシ－３，５，５－トリメチルヘキサノエート、ｔ－ブチルパーオキシラウレート等が挙げられる。これらの有機過酸化物は、単独で用いられてもよいし、２種以上が組み合わせて用いられてもよい。 Examples of the polymerization initiator used in the above polymerization method include azo compounds, organic peroxides, and the like.
Examples of the above azo compounds include 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), ), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 1,1-azobis(cyclohexane-1-carbonitrile), 1-((1-cyano-1-methylethyl)azo ) formamide, 4,4'-azobis(4-cyanovaleric acid), dimethyl-2,2'-azobis(2-methylpropionate), dimethyl-1,1'-azobis(1-cyclohexanecarboxylate), 2,2'-azobis(2-methyl-N-(1,1'-bis(hydroxymethyl)-2-hydroxyethyl)propionamide), 2,2'-azobis(2-methyl-N-(2- hydroxyethyl)propionamide), 2,2'-azobis(N-(2-propenyl)-2-methylpropionamide), 2,2'-azobis(N-butyl-2-methylpropionamide), 2,2 '-Azobis(N-cyclohexyl-2-methylpropionamide), 2,2'-azobis(2-(2-imidazolin-2-yl)propane) dihydrochloride, 2,2'-azobis(2-(1 -(2-hydroxyethyl)-2-imidazolin-2-yl)propane) dihydrochloride, 2,2'-azobis(2-(2-imidazolin-2-yl)propane), 2,2'-azobis( 2-amidinopropane) dihydrochloride, 2,2'-azobis(N-(2-carboxyethyl)-2-methylpropionamidine) tetrahydrate, 2,2'-azobis(1-imino-1-pyrrolidino) -2-methylpropane) dihydrochloride, 2,2'-azobis(2,4,4-trimethylpentane), and the like. These azo compounds may be used alone or in combination of two or more.
Examples of the organic peroxides include 1,1-bis(t-hexylperoxy)-3,3,5-trimethylcyclohexane, t-hexylperoxypivalate, t-butylperoxypivalate, 2,5 -dimethyl-2,5-bis(2-ethylhexanoylperoxy)hexane, t-hexylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxy Examples include isobutyrate, t-butylperoxy-3,5,5-trimethylhexanoate, and t-butylperoxylaurate. These organic peroxides may be used alone or in combination of two or more.
上記重合開始剤のなかでも、官能基を有する重合開始剤が好ましい。
上記官能基を有する重合開始剤を用いることで、上記（メタ）アクリル共重合体の末端に官能基を導入することができ、特に、上記（メタ）アクリル共重合体のうち、架橋性官能基含有モノマーに由来する構成単位が乏しい分子量が比較的小さい分子鎖の末端にも官能基を導入することができる。このような低分子鎖は、末端に官能基を有することで後述する架橋剤を介して架橋構造に取り込まれるため、得られる粘着剤層におけるバルクの凝集力がより大きくなり、該粘着剤層が耐熱性により優れるものとなる。また、架橋構造に関与しない場合であっても、上記低分子鎖は、末端に官能基を有することで後述する架橋剤を介して、又は、後述する架橋剤と後述する粘着付与樹脂等との結合体を介して、該低分子鎖同士が結合体（例えば、二量体等）を形成することができる。このような場合には、上記粘着剤層のゾル成分に含まれる（メタ）アクリル共重合体が全体として高分子量化しているといえる。このため、上記ゾル成分の重量平均分子量等を上述した範囲に調整しやすくなり、得られる粘着剤層におけるバルクの凝集力がより大きくなり、該粘着剤層が耐熱性により優れるものとなる。
上記官能基としては、例えば、水酸基、カルボキシ基、シリル基、グリシジル基、アミノ基、アミド基、ニトリル基、アルコキシ基、アセトアセチル基等が挙げられる。なかでも、水酸基及びカルボキシ基が好ましい。上記官能基を有する重合開始剤として、上述した重合開始剤のなかでは、例えば、２，２’－アゾビス（２－メチル－Ｎ－（１，１’－ビス（ヒドロキシメチル）－２－ヒドロキシエチル）プロピオンアミド）、４，４’－アゾビス（４－シアノバレリアン酸（吉草酸））等が挙げられる。これらの官能基を有する重合開始剤は、単独で用いられてもよいし、２種以上が組み合わせて用いられてもよい。 Among the above polymerization initiators, polymerization initiators having a functional group are preferred.
By using a polymerization initiator having the above-mentioned functional group, it is possible to introduce a functional group to the terminal of the above-mentioned (meth)acrylic copolymer. A functional group can also be introduced at the end of a molecular chain having a relatively small molecular weight and lacking in constituent units derived from the monomer contained therein. Since such low molecular chains have a functional group at the end, they are incorporated into the crosslinked structure via the crosslinking agent described below, so that the bulk cohesive force in the resulting adhesive layer is increased, and the adhesive layer is It has better heat resistance. In addition, even if it does not participate in the crosslinked structure, the low molecular chain has a functional group at the end, so that it can be connected to the crosslinking agent described below or with the tackifier resin described below. The low molecular chains can form a conjugate (for example, a dimer, etc.) via the conjugate. In such a case, it can be said that the (meth)acrylic copolymer contained in the sol component of the pressure-sensitive adhesive layer has a high molecular weight as a whole. Therefore, the weight average molecular weight, etc. of the sol component can be easily adjusted within the above-mentioned range, and the bulk cohesive force in the resulting adhesive layer becomes larger, resulting in the adhesive layer having better heat resistance.
Examples of the functional group include a hydroxyl group, a carboxy group, a silyl group, a glycidyl group, an amino group, an amide group, a nitrile group, an alkoxy group, and an acetoacetyl group. Among these, hydroxyl and carboxy groups are preferred. Among the polymerization initiators mentioned above, examples of the polymerization initiator having the above functional group include 2,2'-azobis(2-methyl-N-(1,1'-bis(hydroxymethyl)-2-hydroxyethyl) ) propionamide), 4,4'-azobis(4-cyanovaleric acid (valeric acid)), and the like. Polymerization initiators having these functional groups may be used alone or in combination of two or more.
上記重合開始剤の添加量は、モノマー混合物１００質量部に対して、好ましい下限が０．０１質量部、好ましい上限が０．５質量部である。上記重合開始剤がこの範囲であることにより、上記ゾル成分の重量平均分子量等を上述した範囲に調整しやすくなる。上記重合開始剤の添加量のより好ましい下限は０．０２質量部、より好ましい上限は０．３質量部である。 The preferable lower limit of the amount of the polymerization initiator added is 0.01 part by weight, and the preferable upper limit is 0.5 parts by weight, based on 100 parts by weight of the monomer mixture. When the polymerization initiator is within this range, it becomes easy to adjust the weight average molecular weight, etc. of the sol component to the above range. A more preferable lower limit of the amount of the polymerization initiator added is 0.02 parts by mass, and a more preferable upper limit is 0.3 parts by mass.
上記フリーラジカル重合においては、連鎖移動剤を用いてもよい。
上記連鎖移動剤としては、例えば、ラウリルメルカプタン、メルカプトプロピオン酸、メルカプトコハク酸、３－メルカプト－１，２－プロパンジオール、１－ブタンチオール、３－メルカプトプロピオン酸シクロヘキシル、メルカプト酢酸２－エチルヘキシル、１－ヘキサデカンチオール、２－メルカプトエタノール、メルカプト酢酸、メルカプト酢酸エチル、１－オクタンチオール、３－メルカプトプロピオン酸トリデシル、チオフェノール等のチオール化合物等が挙げられる。また、２，４－ジフェニル－４－メチル－１－ペンテン等も挙げられる。これらの連鎖移動剤は、単独で用いられてもよいし、２種以上が組み合わせて用いられてもよい。 In the above free radical polymerization, a chain transfer agent may be used.
Examples of the chain transfer agent include lauryl mercaptan, mercaptopropionic acid, mercaptosuccinic acid, 3-mercapto-1,2-propanediol, 1-butanethiol, cyclohexyl 3-mercaptopropionate, 2-ethylhexyl mercaptoacetate, 1 Examples include thiol compounds such as -hexadecanethiol, 2-mercaptoethanol, mercaptoacetic acid, ethyl mercaptoacetate, 1-octanethiol, tridecyl 3-mercaptopropionate, and thiophenol. Also included are 2,4-diphenyl-4-methyl-1-pentene and the like. These chain transfer agents may be used alone or in combination of two or more.
上記連鎖移動剤のなかでも、官能基を有する連鎖移動剤を用いることが好ましい。
上記官能基を有する連鎖移動剤を用いることによっても、上記ゾル成分の重量平均分子量等を上述した範囲に調整しやすくなる。
即ち、上記官能基を有する連鎖移動剤を用いることによっても、上記官能基を有する重合開始剤を用いた場合と同様に、上記低分子鎖の末端に官能基を導入することができ、結果として、得られる粘着剤層におけるバルクの凝集力がより大きくなり、該粘着剤層が耐クリープ性により優れるものとなる。
上記官能基としては、例えば、水酸基、カルボキシ基、シリル基、グリシジル基、アミノ基、アミド基、ニトリル基、アルコキシ基、アセトアセチル基等が挙げられる。なかでも、水酸基及びカルボキシ基が好ましく、水酸基がより好ましい。特に、カルボキシ基が高分子量ポリマー鎖に偏る系では、官能基として水酸基を有する連鎖移動剤を用いて低分子鎖末端に水酸基を入れることで、低分子鎖の架橋反応を優位に進めることができる。
上記官能基を有する連鎖移動剤の官能基数は、架橋構造が高次元化しやすく、ネットワーク化しやすくなり、上記粘着剤層におけるバルクの凝集力がより大きくなることから、複数価であることが好ましい。上記官能基を有する連鎖移動剤として、上述した連鎖移動剤のなかでは、例えば、メルカプトプロピオン酸、メルカプトコハク酸、３－メルカプト－１，２－プロパンジオール等が挙げられる。これらの官能基を有する連鎖移動剤は、単独で用いられてもよいし、２種以上が組み合わせて用いられてもよい。 Among the above chain transfer agents, it is preferable to use a chain transfer agent having a functional group.
By using a chain transfer agent having the above-mentioned functional group, it becomes easier to adjust the weight average molecular weight, etc. of the above-mentioned sol component to the above-mentioned range.
That is, by using a chain transfer agent having the above-mentioned functional group, it is possible to introduce a functional group to the end of the above-mentioned low molecular chain in the same way as when using a polymerization initiator having the above-mentioned functional group, and as a result, , the bulk cohesive force in the resulting adhesive layer becomes larger, and the adhesive layer has better creep resistance.
Examples of the functional group include a hydroxyl group, a carboxy group, a silyl group, a glycidyl group, an amino group, an amide group, a nitrile group, an alkoxy group, and an acetoacetyl group. Among these, hydroxyl group and carboxy group are preferred, and hydroxyl group is more preferred. In particular, in systems where carboxyl groups are biased toward high molecular weight polymer chains, the crosslinking reaction of low molecular chains can be advantageously promoted by using a chain transfer agent that has a hydroxyl group as a functional group to insert a hydroxyl group at the end of the low molecular chain. .
The number of functional groups in the chain transfer agent having the above-mentioned functional groups is preferably multivalent, since the crosslinked structure tends to have higher dimensions, becomes easier to form a network, and the bulk cohesive force in the pressure-sensitive adhesive layer becomes larger. Among the chain transfer agents mentioned above, examples of the chain transfer agent having the above functional group include mercaptopropionic acid, mercaptosuccinic acid, 3-mercapto-1,2-propanediol, and the like. Chain transfer agents having these functional groups may be used alone or in combination of two or more.
上記連鎖移動剤の添加量は、モノマー混合物１００質量部に対して、好ましい下限が０．０１質量部、好ましい上限が０．５質量部である。上記連鎖移動剤の添加量がこの範囲であることにより、上記ゾル成分の重量平均分子量等を上述した範囲に調整しやすくなる。上記連鎖移動剤の添加量のより好ましい下限は０．０２質量部、より好ましい上限は０．３質量部である。 The preferable lower limit of the amount of the chain transfer agent added is 0.01 part by weight and the preferable upper limit is 0.5 part by weight based on 100 parts by weight of the monomer mixture. When the amount of the chain transfer agent added is within this range, it becomes easy to adjust the weight average molecular weight, etc. of the sol component to the above range. A more preferable lower limit of the amount of the chain transfer agent added is 0.02 parts by mass, and a more preferable upper limit is 0.3 parts by mass.
上記フリーラジカル重合においては、分散安定剤を用いてもよい。
上記分散安定剤として、例えば、ポリビニルピロリドン、ポリビニルアルコール、メチルセルロース、エチルセルロース、ポリ（メタ）アクリル酸、ポリ（メタ）アクリル酸エステル、ポリエチレングリコール等が挙げられる。これらの分散安定剤は、単独で用いられてもよいし、２種以上が組み合わせて用いられてもよい。 In the above free radical polymerization, a dispersion stabilizer may be used.
Examples of the dispersion stabilizer include polyvinylpyrrolidone, polyvinyl alcohol, methylcellulose, ethylcellulose, poly(meth)acrylic acid, poly(meth)acrylic acid ester, polyethylene glycol, and the like. These dispersion stabilizers may be used alone or in combination of two or more.
上記フリーラジカル重合において重合溶媒を用いる場合、該重合溶媒としては、例えば、ヘキサン、シクロヘキサン、オクタン、トルエン、キシレン等の非極性溶媒や、水、メタノール、エタノール、プロパノール、ブタノール、アセトン、メチルエチルケトン、メチルイソブチルケトン、テトラヒドロフラン、ジオキサン、Ｎ，Ｎ－ジメチルホルムアミド等の高極性溶媒を用いることができる。これらの重合溶媒は、単独で用いられてもよいし、２種以上が組み合わせて用いられてもよい。 When a polymerization solvent is used in the above free radical polymerization, examples of the polymerization solvent include nonpolar solvents such as hexane, cyclohexane, octane, toluene, and xylene, water, methanol, ethanol, propanol, butanol, acetone, methyl ethyl ketone, and methyl Highly polar solvents such as isobutyl ketone, tetrahydrofuran, dioxane, N,N-dimethylformamide, etc. can be used. These polymerization solvents may be used alone or in combination of two or more.
また、上記フリーラジカル重合における重合温度は、重合速度の観点から０℃～１１０℃であることが好ましい。 Furthermore, the polymerization temperature in the free radical polymerization is preferably 0° C. to 110° C. from the viewpoint of polymerization rate.
上記（メタ）アクリル共重合体は、炭素数６以上のアルキル基を有するモノマーに由来する構成単位を有することが好ましい。上記（メタ）アクリル共重合体が、炭素数６以上のアルキル基を有するモノマーに由来する構成単位を有することにより、粘着剤層のバルクがより柔軟となり、粘着剤溶液の粘度がより下がるものとなるため、加工性がより向上する。
上記炭素数６以上のアルキル基を有するモノマーにおける該炭素数６以上のアルキル基は、炭素数が６以上１６以下であることが好ましい。上記（メタ）アクリル共重合体が、炭素数が６以上１６以下のアルキル基を有するモノマーに由来する構成単位を有することにより、得られる粘着剤層におけるバルクの流動性が上がり、該粘着剤層が粗面に対する接着性により優れるものとなる。上記炭素数６以上のアルキル基を有するモノマーにおける該炭素数６以上のアルキル基は、炭素数が６以上１２以下であることがより好ましい。また、上記炭素数６以上のアルキル基を有するモノマーは、該炭素数６以上のアルキル基が分岐を有していても有していなくてもよいが、分岐を有していないことが好ましい。上記炭素数６以上のアルキル基を有するモノマーのアルキル基が分岐を有していないことにより、上記粘着剤層は、低温から常温では貯蔵弾性率が低い一方で高温においては貯蔵弾性率が高くなるため、耐熱性により優れ、かつ、粗面に対する接着性により優れるものとなる。 The (meth)acrylic copolymer preferably has a structural unit derived from a monomer having an alkyl group having 6 or more carbon atoms. By having the above-mentioned (meth)acrylic copolymer having a structural unit derived from a monomer having an alkyl group having 6 or more carbon atoms, the bulk of the adhesive layer becomes more flexible and the viscosity of the adhesive solution becomes lower. Therefore, workability is further improved.
The alkyl group having 6 or more carbon atoms in the monomer having an alkyl group having 6 or more carbon atoms preferably has 6 or more carbon atoms and 16 or less carbon atoms. Since the above (meth)acrylic copolymer has a structural unit derived from a monomer having an alkyl group having 6 or more and 16 or less carbon atoms, the bulk fluidity of the resulting adhesive layer increases, and the adhesive layer has better adhesion to rough surfaces. The alkyl group having 6 or more carbon atoms in the monomer having an alkyl group having 6 or more carbon atoms more preferably has 6 or more carbon atoms and 12 or less carbon atoms. Further, in the monomer having an alkyl group having 6 or more carbon atoms, the alkyl group having 6 or more carbon atoms may or may not have a branch, but it is preferable that the alkyl group has no branch. Since the alkyl group of the monomer having an alkyl group having 6 or more carbon atoms does not have a branch, the adhesive layer has a low storage modulus at low to normal temperatures, but a high storage modulus at high temperatures. Therefore, it has better heat resistance and better adhesion to rough surfaces.
上記炭素数６以上のアルキル基を有するモノマーとしては、例えば、炭素数６以上のアルキル基を有するアルキル（メタ）アクリレート等が挙げられる。
上記炭素数６以上のアルキル基を有するアルキル（メタ）アクリレートとしては、例えば、ｎ－ヘプチル（メタ）アクリレート、２－エチルヘキシル（メタ）アクリレート、２－オクチル（メタ）アクリレート、イソオクチル（メタ）アクリレート、ｎ－ノニル（メタ）アクリレート、イソノニル（メタ）アクリレート、ラウリル（メタ）アクリレート、ミリスチル（メタ）アクリレート、セチル（メタ）アクリレート、イソステアリルアクリレート、アラキジル（メタ）アクリレート等が挙げられる。これらの炭素数６以上のアルキル基を有するアルキル（メタ）アクリレートは、単独で用いられてもよいし、２種以上が組み合わせて用いられてもよい。なかでも、ｎ－ヘプチル（メタ）アクリレート及び２－エチルヘキシル（メタ）アクリレートが好ましい。
なお、本明細書中において上記「（メタ）アクリレート」は、アクリレート又はメタクリレートを意味する。 Examples of the monomer having an alkyl group having 6 or more carbon atoms include alkyl (meth)acrylates having an alkyl group having 6 or more carbon atoms.
Examples of the alkyl (meth)acrylate having an alkyl group having 6 or more carbon atoms include n-heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-octyl (meth)acrylate, isooctyl (meth)acrylate, Examples include n-nonyl (meth)acrylate, isononyl (meth)acrylate, lauryl (meth)acrylate, myristyl (meth)acrylate, cetyl (meth)acrylate, isostearyl acrylate, arachidyl (meth)acrylate, and the like. These alkyl (meth)acrylates having an alkyl group having 6 or more carbon atoms may be used alone, or two or more types may be used in combination. Among them, n-heptyl (meth)acrylate and 2-ethylhexyl (meth)acrylate are preferred.
In addition, in this specification, the said "(meth)acrylate" means acrylate or methacrylate.
上記（メタ）アクリル共重合体における上記炭素数６以上のアルキル基を有するモノマーに由来する構成単位の含有割合の好ましい下限は５０質量％である。上記炭素数６以上のアルキル基を有するモノマーに由来する構成単位の含有割合が５０質量％以上であることにより、上記（メタ）アクリル共重合体のガラス転移温度が低くなり、得られる粘着剤層におけるバルクの流動性が上がり、該粘着剤層が粗面に対する接着性により優れるものとなる。また、粘着剤層のバルクがより柔軟となり、粘着剤溶液の粘度がより下がるものとなるため、加工性がより向上する。更に、後述する粘着付与樹脂との相溶性も向上する。上記炭素数６以上のアルキル基を有するモノマーに由来する構成単位の含有割合のより好ましい下限は６０質量％、更に好ましい下限は７０質量％である。
また、上記（メタ）アクリル共重合体における上記炭素数６以上のアルキル基を有するモノマーに由来する構成単位の含有割合の好ましい上限は９８質量％である。上記炭素数６以上のアルキル基を有するモノマーに由来する構成単位の含有割合が９８質量％以下であることにより、上記（メタ）アクリル共重合体のガラス転移温度が低くなりすぎることがなく、得られる粘着剤層におけるバルクの凝集力がより大きくなり、該粘着剤層が耐熱性により優れるものとなる。上記炭素数６以上のアルキル基を有するモノマーに由来する構成単位の含有割合のより好ましい上限は９７質量％、更に好ましい上限は９５質量％である。 A preferable lower limit of the content of the structural unit derived from the monomer having an alkyl group having 6 or more carbon atoms in the (meth)acrylic copolymer is 50% by mass. When the content of the structural unit derived from the monomer having an alkyl group having 6 or more carbon atoms is 50% by mass or more, the glass transition temperature of the (meth)acrylic copolymer is lowered, and the resulting adhesive layer The bulk fluidity of the adhesive layer increases, and the adhesive layer has better adhesion to rough surfaces. In addition, the bulk of the adhesive layer becomes more flexible and the viscosity of the adhesive solution is further reduced, so that processability is further improved. Furthermore, the compatibility with the tackifying resin described later is also improved. A more preferable lower limit of the content of the structural unit derived from the monomer having an alkyl group having 6 or more carbon atoms is 60% by mass, and an even more preferable lower limit is 70% by mass.
Further, the preferable upper limit of the content of the structural unit derived from the monomer having an alkyl group having 6 or more carbon atoms in the (meth)acrylic copolymer is 98% by mass. Since the content of the structural unit derived from the monomer having an alkyl group having 6 or more carbon atoms is 98% by mass or less, the glass transition temperature of the (meth)acrylic copolymer does not become too low, and the resulting The bulk cohesive force in the pressure-sensitive adhesive layer becomes larger, and the pressure-sensitive adhesive layer has better heat resistance. A more preferable upper limit of the content of the structural unit derived from the monomer having an alkyl group having 6 or more carbon atoms is 97% by mass, and an even more preferable upper limit is 95% by mass.
上記（メタ）アクリル共重合体は、炭素数５以下のアルキル基を有するアルキル（メタ）アクリレートに由来する構成単位を有していてもよい。
上記炭素数５以下のアルキル基を有するアルキル（メタ）アクリレートとしては、例えば、メチル（メタ）アクリレート、エチル（メタ）アクリレート、ｎ－プロピル（メタ）アクリレート、イソプロピル（メタ）アクリレート、ブチル（メタ）アクリレート等が挙げられる。これらの炭素数５以下のアルキル基を有するアルキル（メタ）アクリレートは、単独で用いられてもよいし、２種以上が組み合わせて用いられてもよい。なかでも、ブチル（メタ）アクリレートが好ましい。 The (meth)acrylic copolymer may have a structural unit derived from an alkyl (meth)acrylate having an alkyl group having 5 or less carbon atoms.
Examples of the alkyl (meth)acrylate having an alkyl group having 5 or less carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, and butyl (meth)acrylate. Examples include acrylate. These alkyl (meth)acrylates having an alkyl group having 5 or less carbon atoms may be used alone, or two or more types may be used in combination. Among them, butyl (meth)acrylate is preferred.
上記炭素数５以下のアルキル基を有するアルキル（メタ）アクリレートに由来する構成単位の含有割合は２５質量％以上５０質量％未満であることが好ましい。上記炭素数５以下のアルキル基を有するアルキル（メタ）アクリレートに由来する構成単位の含有割合が２５質量％以上であることにより、上記（メタ）アクリル共重合体のガラス転移温度が充分に高くなるため、得られる粘着剤層におけるバルクの凝集力がより大きくなり、該粘着剤層が耐熱性により優れるものとなる。上記含有割合が５０質量％未満であれば、上記（メタ）アクリル共重合体のガラス転移温度が高くなりすぎることがなく、得られる粘着剤層におけるバルクの流動性が上がり、該粘着剤層が粗面に対する接着性により優れるものとなる。上記含有割合のより好ましい下限は３０質量％、より好ましい上限は４５質量％である。 The content of the structural unit derived from the alkyl (meth)acrylate having an alkyl group having 5 or less carbon atoms is preferably 25% by mass or more and less than 50% by mass. When the content of the structural unit derived from the alkyl (meth)acrylate having an alkyl group having 5 or less carbon atoms is 25% by mass or more, the glass transition temperature of the (meth)acrylic copolymer becomes sufficiently high. Therefore, the bulk cohesive force in the resulting adhesive layer becomes larger, and the adhesive layer has better heat resistance. If the content ratio is less than 50% by mass, the glass transition temperature of the (meth)acrylic copolymer will not become too high, the bulk fluidity of the resulting adhesive layer will increase, and the adhesive layer will be It has better adhesion to rough surfaces. A more preferable lower limit of the content ratio is 30% by mass, and a more preferable upper limit is 45% by mass.
上記（メタ）アクリル共重合体は、架橋性官能基含有モノマーに由来する構成単位を有することが好ましい。上記（メタ）アクリル共重合体が上記架橋性官能基含有モノマーに由来する構成単位を有することにより、上記（メタ）アクリル共重合体及び後述する粘着付与樹脂等が後述する架橋剤を介して架橋構造を構築することで、得られる粘着剤層におけるバルクの凝集力がより大きくなり、該粘着剤層が耐熱性により優れるものとなる。上記架橋性官能基としては、例えば、水酸基、カルボキシ基、シリル基、グリシジル基、アミノ基、アミド基、ニトリル基、アルコキシ基、アセトアセチル基等が挙げられる。なかでも、上記粘着剤層におけるバルクの凝集力の調整が容易であることから、水酸基及びカルボキシ基が好ましい。 The (meth)acrylic copolymer preferably has a structural unit derived from a crosslinkable functional group-containing monomer. Since the (meth)acrylic copolymer has a structural unit derived from the crosslinkable functional group-containing monomer, the (meth)acrylic copolymer and the tackifying resin described below are crosslinked via the crosslinking agent described below. By constructing the structure, the bulk cohesive force in the resulting adhesive layer becomes larger, and the adhesive layer has better heat resistance. Examples of the crosslinkable functional group include a hydroxyl group, a carboxy group, a silyl group, a glycidyl group, an amino group, an amide group, a nitrile group, an alkoxy group, and an acetoacetyl group. Among these, hydroxyl groups and carboxy groups are preferred because the bulk cohesive force in the pressure-sensitive adhesive layer can be easily adjusted.
上記架橋性官能基として水酸基を有する架橋性官能基含有モノマーとしては、例えば、４－ヒドロキシブチル（メタ）アクリレート、２－ヒドロキシエチル（メタ）アクリレート、ヒドロキシプロピル（メタ）アクリレート等が挙げられる。
上記架橋性官能基としてカルボキシ基を有する架橋性官能基含有モノマーとしては、例えば、（メタ）アクリル酸、イタコン酸、無水マレイン酸、クロトン酸、マレイン酸、フマル酸等が挙げられる。なかでも、アクリル酸が好ましい。
上記架橋性官能基としてグリシジル基を有する架橋性官能基含有モノマーとしては、例えば、グリシジル（メタ）アクリレートが挙げられる。
上記架橋性官能基としてアミド基を有する架橋性官能基含有モノマーとしては、例えば、ヒドロキシエチルアクリルアミド、イソプロピルアクリルアミド、ジメチルアミノプロピルアクリルアミド等が挙げられる。
上記架橋性官能基としてニトリル基を有する架橋性官能基含有モノマーとしては、例えば、アクリロニトリル等が挙げられる。 Examples of the crosslinkable functional group-containing monomer having a hydroxyl group as the crosslinkable functional group include 4-hydroxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, and hydroxypropyl (meth)acrylate.
Examples of the crosslinkable functional group-containing monomer having a carboxy group as the crosslinkable functional group include (meth)acrylic acid, itaconic acid, maleic anhydride, crotonic acid, maleic acid, fumaric acid, etc. Of these, acrylic acid is preferred.
An example of the crosslinkable functional group-containing monomer having a glycidyl group as the crosslinkable functional group is glycidyl (meth)acrylate.
Examples of the crosslinkable functional group-containing monomer having an amide group as the crosslinkable functional group include hydroxyethylacrylamide, isopropylacrylamide, and dimethylaminopropylacrylamide.
Examples of the crosslinkable functional group-containing monomer having a nitrile group as the crosslinkable functional group include acrylonitrile.
上記（メタ）アクリル共重合体における上記架橋性官能基含有モノマーに由来する構成単位の含有割合の好ましい下限は０．０５質量％、好ましい上限は２０質量％である。上記架橋性官能基含有モノマーに由来する構成単位の含有割合が０．０５質量％以上であることにより、得られる粘着剤層におけるバルクの凝集力がより大きくなり、該粘着剤層が耐熱性により優れるものとなる。上記架橋性官能基含有モノマーに由来する構成単位の含有割合が２０質量％以下であることにより、得られる粘着剤層におけるバルクの流動性が上がり、該粘着剤層が粗面に対する接着性により優れるものとなる。上記架橋性官能基含有モノマーに由来する構成単位の含有割合のより好ましい下限は０．１質量％、より好ましい上限は１５質量％である。 The preferable lower limit of the content of the structural unit derived from the crosslinkable functional group-containing monomer in the (meth)acrylic copolymer is 0.05% by mass, and the preferable upper limit is 20% by mass. When the content of the structural unit derived from the crosslinkable functional group-containing monomer is 0.05% by mass or more, the bulk cohesive force in the resulting adhesive layer becomes larger, and the adhesive layer has better heat resistance. Become excellent. When the content of the structural unit derived from the crosslinkable functional group-containing monomer is 20% by mass or less, the bulk fluidity of the resulting adhesive layer increases, and the adhesive layer has better adhesion to rough surfaces. Become something. A more preferable lower limit of the content of the structural units derived from the crosslinkable functional group-containing monomer is 0.1% by mass, and a more preferable upper limit is 15% by mass.
上記（メタ）アクリル共重合体が上記架橋性官能基として水酸基を有する架橋性官能基含有モノマーに由来する構成単位を有する場合、該架橋性官能基含有モノマーに由来する構成単位の含有割合の好ましい下限は０．０３質量％、好ましい上限は１質量％である。上記架橋性官能基として水酸基を有する架橋性官能基含有モノマーに由来する構成単位の含有割合が０．０３質量％以上であることにより、得られる粘着剤層におけるバルクの凝集力がより大きくなり、該粘着剤層が耐熱性により優れるものとなる。上記架橋性官能基として水酸基を有する架橋性官能基含有モノマーに由来する構成単位の含有割合が１質量％以下であることにより、得られる粘着剤層のゲル分率が高くなりすぎることなく、該粘着剤層が粗面に対する接着性により優れるものとなる。上記架橋性官能基として水酸基を有する架橋性官能基含有モノマーに由来する構成単位の含有割合のより好ましい下限は０．０５質量％、更に好ましい下限は０．０６質量％であり、より好ましい上限は０．５質量％、更に好ましい上限は０．３質量％、特に好ましい上限は０．１質量％である。
また、上記（メタ）アクリル共重合体が上記架橋性官能基としてカルボキシ基を有する架橋性官能基含有モノマーに由来する構成単位を有する場合、該架橋性官能基含有モノマーに由来する構成単位の含有割合の好ましい下限は２質量％、好ましい上限は１５質量％である。上記架橋性官能基としてカルボキシ基を有する架橋性官能基含有モノマーに由来する構成単位の含有割合が２質量％以上であることにより、得られる粘着剤層のゲル分率が高くなりやすく、上記（メタ）アクリル共重合体のガラス転移温度が充分に高くなるため、得られる粘着剤層におけるバルクの凝集力がより大きくなる。その結果、該粘着剤層が耐熱性により優れるものとなる。上記架橋性官能基としてカルボキシ基を有する架橋性官能基含有モノマーに由来する構成単位の含有割合が１５質量％以下であることにより、上記（メタ）アクリル共重合体のガラス転移温度が高くなりすぎることなく、該粘着剤層が粗面に対する接着性により優れるものとなる。上記架橋性官能基としてカルボキシ基を有する架橋性官能基含有モノマーに由来する構成単位の含有割合のより好ましい下限は３質量％、更に好ましい下限は５質量％であり、より好ましい上限は１０質量％、更に好ましい上限は８質量％である。 When the (meth)acrylic copolymer has a structural unit derived from a crosslinkable functional group-containing monomer having a hydroxyl group as the crosslinkable functional group, the preferable content ratio of the structural unit derived from the crosslinkable functional group-containing monomer is The lower limit is 0.03% by mass, and the preferable upper limit is 1% by mass. When the content of the structural unit derived from the crosslinkable functional group-containing monomer having a hydroxyl group as the crosslinkable functional group is 0.03% by mass or more, the bulk cohesive force in the resulting adhesive layer becomes larger, The adhesive layer has better heat resistance. Since the content of the structural unit derived from the crosslinkable functional group-containing monomer having a hydroxyl group as the crosslinkable functional group is 1% by mass or less, the gel fraction of the resulting pressure-sensitive adhesive layer does not become too high. The adhesive layer has better adhesion to rough surfaces. A more preferable lower limit of the content ratio of the structural unit derived from a crosslinkable functional group-containing monomer having a hydroxyl group as the crosslinkable functional group is 0.05% by mass, an even more preferable lower limit is 0.06% by mass, and a more preferable upper limit is The upper limit is preferably 0.5% by weight, more preferably 0.3% by weight, and particularly preferably 0.1% by weight.
In addition, when the (meth)acrylic copolymer has a structural unit derived from a crosslinkable functional group-containing monomer having a carboxy group as the crosslinkable functional group, the content of the structural unit derived from the crosslinkable functional group-containing monomer The preferable lower limit of the ratio is 2% by mass, and the preferable upper limit is 15% by mass. When the content of the structural unit derived from the crosslinkable functional group-containing monomer having a carboxyl group as the crosslinkable functional group is 2% by mass or more, the gel fraction of the resulting adhesive layer tends to be high, and the above ( Since the glass transition temperature of the meth)acrylic copolymer becomes sufficiently high, the bulk cohesive force in the resulting pressure-sensitive adhesive layer becomes larger. As a result, the adhesive layer has better heat resistance. When the content of the structural unit derived from the crosslinkable functional group-containing monomer having a carboxyl group as the crosslinkable functional group is 15% by mass or less, the glass transition temperature of the (meth)acrylic copolymer becomes too high. Without this, the adhesive layer has better adhesion to rough surfaces. A more preferable lower limit of the content of the structural unit derived from the crosslinkable functional group-containing monomer having a carboxyl group as the crosslinkable functional group is 3% by mass, an even more preferable lower limit is 5% by mass, and a more preferable upper limit is 10% by mass. A more preferable upper limit is 8% by mass.
上記（メタ）アクリル共重合体は、必要に応じて、上記炭素数６以上のアルキル基を有するモノマーに由来する構成単位、上記炭素数５以下のアルキル基を有するアルキル（メタ）アクリレートに由来する構成単位、及び、上記架橋性官能基含有モノマーに由来する構成単位以外の共重合可能な他の重合性モノマーに由来する構成単位を有していてもよい。 The above-mentioned (meth)acrylic copolymer is derived from a structural unit derived from the above-mentioned monomer having an alkyl group having 6 or more carbon atoms, or an alkyl (meth)acrylate having the above-mentioned alkyl group having 5 or less carbon atoms, as necessary. It may have a structural unit and a structural unit derived from another polymerizable monomer that can be copolymerized other than the structural unit derived from the above-mentioned crosslinkable functional group-containing monomer.
上記粘着剤は、架橋剤を含む。
上記架橋剤としては、上記（メタ）アクリル共重合体の架橋性官能基の種類に応じて、例えば、イソシアネート系架橋剤、アジリジン系架橋剤、エポキシ系架橋剤、金属キレート型架橋剤等が選択して用いられる。なかでも、水酸基及びカルボキシ基に対して選択的に架橋することができ、架橋構造を制御しやすいことから、イソシアネート系架橋剤が好ましい。特に、１分子中に２以上のイソシアネート機を有するイソシアネート系架橋剤を上記架橋剤１００質量部中に８０質量部以上含むことが好ましい。
上記イソシアネート系架橋剤のうち市販されているものとしては、例えば、コロネートＨＸ、コロネートＬ（いずれも東ソー社製）、マイテックＮＹ２６０Ａ（三菱ケミカル社製）等が挙げられる。 The pressure-sensitive adhesive includes a crosslinking agent.
As the crosslinking agent, for example, an isocyanate crosslinking agent, an aziridine crosslinking agent, an epoxy crosslinking agent, a metal chelate type crosslinking agent, etc. are selected depending on the type of crosslinkable functional group of the (meth)acrylic copolymer. It is used as Among these, isocyanate-based crosslinking agents are preferred because they can selectively crosslink hydroxyl groups and carboxyl groups and the crosslinked structure can be easily controlled. In particular, it is preferable that 80 parts by mass or more of an isocyanate-based crosslinking agent having two or more isocyanate units in one molecule is contained in 100 parts by mass of the crosslinking agent.
Examples of commercially available isocyanate-based crosslinking agents include Coronate HX, Coronate L (all manufactured by Tosoh Corporation), Mytec NY260A (manufactured by Mitsubishi Chemical Corporation), and the like.
上記架橋剤の官能基数は、架橋構造が高次元化しやすく、ネットワーク化しやすくなり、得られる粘着剤層におけるバルクの凝集力がより大きくなることから、複数価であることが好ましい。 The number of functional groups in the crosslinking agent is preferably multivalent, since the crosslinked structure tends to have higher dimensions, becomes easier to form a network, and the bulk cohesive force in the resulting pressure-sensitive adhesive layer becomes larger.
上記粘着剤は、粘着付与樹脂を含む。
上記粘着剤が上記粘着付与樹脂を含有することにより、得られる粘着剤層が被着体に対して接着性に優れるものとなる。 The pressure-sensitive adhesive contains a tackifier resin.
When the pressure-sensitive adhesive contains the tackifier resin, the resulting pressure-sensitive adhesive layer has excellent adhesion to the adherend.
上記粘着付与樹脂の軟化温度の好ましい下限は９０℃、好ましい上限は１８０℃である。上記粘着付与樹脂の軟化温度が９０℃以上であることにより、上記粘着剤層が耐熱性により優れるものとなり、高温における耐クリープ性がより向上する。上記粘着付与樹脂の軟化温度が１８０℃以下であることにより、上記粘着剤層が柔軟になりやすく、粗面に対する接着性により優れるものとなる。上記粘着付与樹脂の軟化温度のより好ましい下限は１００℃、更に好ましい下限は１１０℃、特に好ましい下限は１２０℃であり、より好ましい上限は１７０℃、更に好ましい上限は１６５℃である。
なお、上記「軟化温度」は、ＪＩＳ　Ｋ２２０７環球法により測定される軟化温度を意味する。 The preferable lower limit of the softening temperature of the tackifier resin is 90°C, and the preferable upper limit is 180°C. When the softening temperature of the tackifier resin is 90° C. or higher, the adhesive layer has better heat resistance, and the creep resistance at high temperatures is further improved. When the softening temperature of the tackifier resin is 180° C. or less, the adhesive layer becomes easily flexible and has excellent adhesiveness to rough surfaces. A more preferable lower limit of the softening temperature of the tackifying resin is 100°C, an even more preferable lower limit is 110°C, an especially preferable lower limit is 120°C, a more preferable upper limit is 170°C, and an even more preferable upper limit is 165°C.
In addition, the above-mentioned "softening temperature" means the softening temperature measured by JIS K2207 ring and ball method.
上記粘着付与樹脂の水酸基価の好ましい下限は１０ｍｇＫＯＨ／ｇ、好ましい上限は２００ｍｇＫＯＨ／ｇである。上記粘着付与樹脂の水酸基価が１０ｍｇＫＯＨ／ｇ以上であることにより、上記粘着付与樹脂の軟化温度が高くなりやすい。上記粘着付与樹脂の水酸基価が２００ｍｇＫＯＨ／ｇ以下であることにより、上記架橋剤との反応性が高くなりすぎず、上記（メタ）アクリル共重合体の架橋を阻害したり、（メタ）アクリル共重合体とグラフト反応を起こしたりすることを抑制することができる。上記粘着付与樹脂の水酸基価のより好ましい下限は２０ｍｇＫＯＨ／ｇ、更に好ましい下限は２５ｍｇＫＯＨ／ｇ、特に好ましい下限は３０ｍｇＫＯＨ／ｇであり、より好ましい上限は１５０ｍｇＫＯＨ／ｇ、更に好ましい上限は１２０ｍｇＫＯＨ／ｇ、特に好ましい上限は１００ｍｇＫＯＨ／ｇである。
なお、上記「水酸基価」は、ＪＩＳ　Ｋ１５５７（無水フタル酸法）により測定できる。 The preferable lower limit of the hydroxyl value of the tackifying resin is 10 mgKOH/g, and the preferable upper limit is 200 mgKOH/g. When the hydroxyl value of the tackifier resin is 10 mgKOH/g or more, the softening temperature of the tackifier resin tends to be high. By setting the hydroxyl value of the tackifying resin to 200 mgKOH/g or less, the reactivity with the crosslinking agent will not become too high, and the crosslinking of the (meth)acrylic copolymer will not be inhibited or the (meth)acrylic copolymer will not be inhibited. It is possible to suppress a graft reaction from occurring with the polymer. A more preferable lower limit of the hydroxyl value of the tackifier resin is 20 mgKOH/g, an even more preferable lower limit is 25 mgKOH/g, an especially preferable lower limit is 30 mgKOH/g, a more preferable upper limit is 150 mgKOH/g, an even more preferable upper limit is 120 mgKOH/g, A particularly preferable upper limit is 100 mgKOH/g.
In addition, the above-mentioned "hydroxyl value" can be measured according to JIS K1557 (phthalic anhydride method).
上記粘着付与樹脂としては、例えば、ロジンエステル系樹脂等のロジン系樹脂、テルペンフェノール樹脂等のテルペン系樹脂、石油系樹脂等が挙げられる。これらの粘着付与樹脂は、単独で用いられてもよいし、２種以上が組み合わせて用いられてもよい。
なかでも、ロジンエステル系樹脂、テルペンフェノール樹脂、及び、これらの組み合わせが好ましく、テルペンフェノール樹脂がより好ましい。 Examples of the tackifier resin include rosin resins such as rosin ester resins, terpene resins such as terpene phenol resins, petroleum resins, and the like. These tackifying resins may be used alone or in combination of two or more.
Among these, rosin ester resins, terpene phenol resins, and combinations thereof are preferred, and terpene phenol resins are more preferred.
上記テルペンフェノール樹脂は、フェノールの存在下においてテルペンを重合させて得られた樹脂である。上記テルペンフェノール樹脂は、上記（メタ）アクリル共重合体との相溶性がよく、上記（メタ）アクリル共重合体とのグラフト化が進みやすく、上記粘着剤層の内部に取り込まれやすい。このため、上記粘着剤層の表面はポリマーリッチとなって柔軟になり、粗面に対してより高い接着力を有することができる。一方、上記テルペンフェノール樹脂と上記（メタ）アクリル共重合体とのグラフト化によって上記粘着剤層のバルクの凝集力がより上がることから、上記粘着剤層は、耐クリープ性により優れるものとなる。 The above-mentioned terpene phenol resin is a resin obtained by polymerizing terpene in the presence of phenol. The terpene phenol resin has good compatibility with the (meth)acrylic copolymer, is easily grafted with the (meth)acrylic copolymer, and is easily incorporated into the adhesive layer. Therefore, the surface of the pressure-sensitive adhesive layer becomes polymer-rich and flexible, and can have higher adhesive strength to rough surfaces. On the other hand, since the bulk cohesive force of the adhesive layer is further increased by grafting the terpene phenol resin and the (meth)acrylic copolymer, the adhesive layer has better creep resistance.
上記テルペン系樹脂のうち市販されているものとしては、例えば、ＹＳポリスターＧ１５０（水酸基価１４０ｍｇＫＯＨ／ｇ、軟化温度１５０℃）、ＹＳポリスターＴ１００（水酸基価６０ｍｇＫＯＨ／ｇ、軟化温度１００℃）、ＹＳポリスターＧ１２５（水酸基価１４０ｍｇＫＯＨ／ｇ、軟化温度１２５℃）、ＹＳポリスターＴ１１５（水酸基価６０ｍｇＫＯＨ／ｇ、軟化温度１１５℃）、ＹＳポリスターＴ１３０（水酸基価６０ｍｇＫＯＨ／ｇ、軟化温度１３０℃）、ＹＳポリスターＴ１６０（水酸基価６０ｍｇＫＯＨ／ｇ、軟化温度１６０℃）（いずれもヤスハラケミカル社製）等が挙げられる。 Among the above terpene resins, commercially available ones include, for example, YS Polystar G150 (hydroxyl value 140 mgKOH/g, softening temperature 150°C), YS Polyster T100 (hydroxyl value 60 mgKOH/g, softening temperature 100°C), YS Polyster G125 (hydroxyl value 140mgKOH/g, softening temperature 125°C), YS Polyster T115 (hydroxyl value 60mgKOH/g, softening temperature 115°C), YS Polyster T130 (hydroxyl value 60mgKOH/g, softening temperature 130°C), YS Polyster T160 ( Hydroxyl value: 60 mgKOH/g, softening temperature: 160° C.) (both manufactured by Yasuhara Chemical Co., Ltd.).
上記ロジンエステル系樹脂とは、アビエチン酸を主成分とするロジン樹脂、不均化ロジン樹脂、水添ロジン樹脂、アビエチン酸等の樹脂酸の二量体（重合ロジン樹脂）等を、アルコールによってエステル化させて得られた樹脂である。エステル化に用いたアルコールの水酸基の一部がエステル化に使用されずに樹脂内に含有されることで、水酸基価が上述した範囲に調整される。アルコールとしては、エチレングリコール、グリセリン、ペンタエリスリトール等の多価アルコールが挙げられる。
なお、ロジン樹脂をエステル化した樹脂がロジンエステル樹脂、不均化ロジン樹脂をエステル化した樹脂が不均化ロジンエステル樹脂、水添ロジン樹脂をエステル化した樹脂が水添ロジンエステル樹脂、重合ロジン樹脂をエステル化した樹脂が重合ロジンエステル樹脂である。 The above-mentioned rosin ester resins are rosin resins whose main component is abietic acid, disproportionated rosin resins, hydrogenated rosin resins, dimers of resin acids such as abietic acid (polymerized rosin resins), etc., and esterified with alcohol. This is a resin obtained by A part of the hydroxyl group of the alcohol used for esterification is not used for esterification but is contained in the resin, so that the hydroxyl value is adjusted to the above-mentioned range. Examples of the alcohol include polyhydric alcohols such as ethylene glycol, glycerin, and pentaerythritol.
Furthermore, resin obtained by esterifying rosin resin is called rosin ester resin, resin obtained by esterifying disproportionated rosin resin is called disproportionated rosin ester resin, resin obtained by esterifying hydrogenated rosin resin is called hydrogenated rosin ester resin, and polymerized rosin resin. A resin obtained by esterifying a resin is a polymerized rosin ester resin.
上記不均化ロジンエステル樹脂のうち市販されているものとしては、例えば、スーパーエステルＡ７５（水酸基価２３ｍｇＫＯＨ／ｇ、軟化温度７５℃）、スーパーエステルＡ１００（水酸基価１６ｍｇＫＯＨ／ｇ、軟化温度１００℃）、スーパーエステルＡ１１５（水酸基価１９ｍｇＫＯＨ／ｇ、軟化温度１１５℃）、スーパーエステルＡ１２５（水酸基価１５ｍｇＫＯＨ／ｇ、軟化温度１２５℃）（いずれも荒川化学工業社製）等が挙げられる。
上記水添ロジンエステル樹脂としては、例えば、パインクリスタルＫＥ－３５９（水酸基価４２ｍｇＫＯＨ／ｇ、軟化温度１００℃）、エステルガムＨ（水酸基価２９ｍｇＫＯＨ／ｇ、軟化温度７０℃）（いずれも荒川化学工業社製）等が挙げられる。
上記重合ロジンエステル樹脂としては、例えば、ペンセルＤ１３５（水酸基価４５ｍｇＫＯＨ／ｇ、軟化温度１３５℃）、ペンセルＤ１２５（水酸基価３４ｍｇＫＯＨ／ｇ、軟化温度１２５℃）、ペンセルＤ１６０（水酸基価４２ｍｇＫＯＨ／ｇ、軟化温度１６０℃）（いずれも荒川化学工業社製）等が挙げられる。 Commercially available disproportionated rosin ester resins include, for example, Super Ester A75 (hydroxyl value 23 mgKOH/g, softening temperature 75°C), Super Ester A100 (hydroxyl value 16 mgKOH/g, softening temperature 100°C). , Super Ester A115 (hydroxyl value: 19 mgKOH/g, softening temperature: 115°C), Super Ester A125 (hydroxyl value: 15 mgKOH/g, softening temperature: 125°C) (all manufactured by Arakawa Chemical Industries, Ltd.).
Examples of the hydrogenated rosin ester resin include Pine Crystal KE-359 (hydroxyl value 42 mgKOH/g, softening temperature 100°C), Ester Gum H (hydroxyl value 29 mgKOH/g, softening temperature 70°C) (both manufactured by Arakawa Chemical Co., Ltd. company), etc.
Examples of the polymerized rosin ester resin include Pencel D135 (hydroxyl value 45 mgKOH/g, softening temperature 135°C), Pencel D125 (hydroxyl value 34 mgKOH/g, softening temperature 125°C), Pencel D160 (hydroxyl value 42mgKOH/g, softening temperature 125°C), (temperature: 160° C.) (all manufactured by Arakawa Chemical Industries, Ltd.).
上記粘着付与樹脂の含有量は、上記（メタ）アクリル共重合体１００質量部に対して、好ましい下限が１０質量部、好ましい上限が６０質量部である。上記粘着付与樹脂の含有量が上記範囲内であることにより、上記粘着剤層が界面の接着性により優れ、保持性能により優れるものとなる。上記含有量のより好ましい下限は１５質量部、更に好ましい下限は２０質量部であり、より好ましい上限は５０質量部、更に好ましい上限は４５質量部である。 The content of the tackifier resin has a preferable lower limit of 10 parts by weight and a preferable upper limit of 60 parts by weight based on 100 parts by weight of the (meth)acrylic copolymer. When the content of the tackifier resin is within the above range, the adhesive layer has better interfacial adhesion and better retention performance. A more preferable lower limit of the content is 15 parts by weight, an even more preferable lower limit is 20 parts by weight, a more preferable upper limit is 50 parts by weight, and an even more preferable upper limit is 45 parts by weight.
上記粘着剤は、必要に応じて、溶剤、可塑剤、乳化剤、軟化剤、充填剤、顔料、染料、シランカップリング剤、酸化防止剤等の添加剤を含有していてもよい。本発明の粘着テープでは、製造プロセスにおいて排出されるＣＯ２の由来となる上記溶剤の量を低減することができる。 The pressure-sensitive adhesive may contain additives such as a solvent, a plasticizer, an emulsifier, a softener, a filler, a pigment, a dye, a silane coupling agent, and an antioxidant, as necessary. With the adhesive tape of the present invention, it is possible to reduce the amount of the above-mentioned solvent, which is the source of CO 2 discharged during the manufacturing process.
上記粘着剤は、水酸基を有する化合物を固形分中０．０３質量％以上含み、かつ、カルボキシ基を有する化合物を固形分中２質量％以上含むことが好ましい。上記粘着剤が、水酸基を有する化合物を固形分中０．０３質量％以上含み、かつ、カルボキシ基を有する化合物を固形分中２質量％以上含むことにより、得られる粘着剤層におけるバルクの凝集力がより大きくなり、上記粘着剤層が耐熱性により優れるものとなる。上記粘着剤は、上記水酸基を有する化合物を０．０５質量％以上含むことがより好ましい。また、上記粘着剤は、上記カルボキシ基を有する化合物を３質量％以上含むことがより好ましい。
なお、上記水酸基を有する化合物及び上記カルボキシ基を有する化合物は、上記粘着剤の固形分に含まれるいずれの成分であってもよい。
なお、上記「固形分」は、溶剤を除く成分を意味する。 It is preferable that the pressure-sensitive adhesive contains 0.03% by mass or more of a compound having a hydroxyl group in the solid content, and 2% by mass or more of the compound having a carboxy group in the solid content. Bulk cohesive strength in the adhesive layer obtained by the above-mentioned adhesive containing 0.03% by mass or more of a compound having a hydroxyl group in the solid content and 2% by mass or more of the compound having a carboxy group in the solid content becomes larger, and the adhesive layer has better heat resistance. It is more preferable that the pressure-sensitive adhesive contains 0.05% by mass or more of the compound having a hydroxyl group. Moreover, it is more preferable that the above-mentioned pressure-sensitive adhesive contains 3% by mass or more of the above-mentioned compound having a carboxyl group.
Note that the compound having a hydroxyl group and the compound having a carboxyl group may be any component contained in the solid content of the pressure-sensitive adhesive.
In addition, the above-mentioned "solid content" means components excluding the solvent.
上記粘着剤を塗工する際の粘度の好ましい上限は１万ｍＰａ・ｓである。上記粘着剤を塗工する際の粘度が１万ｍＰａ・ｓ以下であることにより、気泡や糊スジ等の不具合なく平滑に粘着剤を塗工することが容易となる。上記粘着剤を塗工する際の粘度のより好ましい上限は９０００ｍＰａ・ｓ、更に好ましい上限は８０００ｍＰａ・ｓである。
また、上記粘着剤を塗工する際の粘度の好ましい下限は１５００ｍＰａ・ｓである。上記粘着剤を塗工する際の粘度が１５００ｍＰａ・ｓ以上であることにより、粘着剤を押し出す際の圧力が充分に得られ、目的の厚みや幅で粘着剤を塗工することが容易となる。上記粘着剤を塗工する際の粘度のより好ましい下限は２０００ｍＰａ・ｓである。
上記粘着剤を塗工する際の粘度は、Ｂ型粘度計を用いて、２３℃、１２ｒｐｍの条件で測定することができる。 The preferable upper limit of the viscosity when applying the above adhesive is 10,000 mPa·s. By having a viscosity of 10,000 mPa·s or less when applying the above-mentioned adhesive, it becomes easy to apply the adhesive smoothly without problems such as bubbles or adhesive streaks. A more preferable upper limit of the viscosity when applying the pressure-sensitive adhesive is 9000 mPa·s, and an even more preferable upper limit is 8000 mPa·s.
Further, the preferable lower limit of the viscosity when applying the above-mentioned pressure-sensitive adhesive is 1500 mPa·s. By having a viscosity of 1500 mPa・s or more when applying the above-mentioned adhesive, sufficient pressure can be obtained when extruding the adhesive, making it easy to apply the adhesive to the desired thickness and width. . A more preferable lower limit of the viscosity when applying the pressure-sensitive adhesive is 2000 mPa·s.
The viscosity when applying the adhesive can be measured using a B-type viscometer at 23° C. and 12 rpm.
上記粘着剤層のガラス転移温度の好ましい下限は－１０℃、好ましい上限は３０℃である。上記粘着剤層のガラス転移温度が－１０℃以上であることにより、耐熱性が高く、バルクの凝集力も高くなるため、保持性能や高温耐反発性により優れるものとなる。上記粘着剤層のガラス転移温度が３０℃以下であることにより、界面に対する接着性により優れるものとなる。上記粘着剤層のガラス転移温度のより好ましい下限は－５℃、更に好ましい下限は０℃、更により好ましい下限は５℃であり、より好ましい上限は２５℃、更に好ましい上限は２０℃、更により好ましい上限は１５℃である。
なお、本明細書において上記「ガラス転移温度」は、動的粘弾性測定により得られる損失正接（ｔａｎδ）の極大のうち、ミクロブラウン運動に起因する極大が現れる温度を意味する。
上記粘着剤層のガラス転移温度及び後述する貯蔵弾性率の測定で行う動的粘弾性測定としては、例えば、次の方法を採用することができる。
即ち、まず、上記粘着剤層のサンプルを重ね合わせ、厚み１ｍｍ程度の積層体を作製し、６ｍｍ×１０ｍｍに裁断して試験片を得る。得られた試験片について、動的粘弾性測定装置（アイティー計測制御社、「ＤＶＡ－２００」）を用い、せん断モードにて窒素雰囲気下、測定温度－４０℃～１４０℃、昇温速度５℃／ｍｉｎ、周波数１０Ｈｚ、ひずみ０．０８％で動的粘弾性測定を行う。 The preferable lower limit of the glass transition temperature of the pressure-sensitive adhesive layer is -10°C, and the preferable upper limit is 30°C. When the glass transition temperature of the adhesive layer is −10° C. or higher, the adhesive layer has high heat resistance and high bulk cohesive force, resulting in better retention performance and high-temperature repulsion resistance. When the glass transition temperature of the pressure-sensitive adhesive layer is 30° C. or lower, the adhesive layer has better adhesion to the interface. A more preferable lower limit of the glass transition temperature of the pressure-sensitive adhesive layer is -5°C, an even more preferable lower limit is 0°C, an even more preferable lower limit is 5°C, a more preferable upper limit is 25°C, an even more preferable upper limit is 20°C, and an even more preferable upper limit. The preferred upper limit is 15°C.
In this specification, the above-mentioned "glass transition temperature" means the temperature at which the maximum due to micro-Brownian motion appears among the maximum loss tangent (tan δ) obtained by dynamic viscoelasticity measurement.
For example, the following method can be adopted as the dynamic viscoelasticity measurement performed to measure the glass transition temperature of the adhesive layer and the storage modulus described below.
That is, first, samples of the above-mentioned pressure-sensitive adhesive layers are stacked to form a laminate having a thickness of about 1 mm, and the laminate is cut into a size of 6 mm x 10 mm to obtain a test piece. The obtained test piece was measured using a dynamic viscoelasticity measuring device (IT Keizai Control Co., Ltd., "DVA-200") under a nitrogen atmosphere in shear mode at a measurement temperature of -40°C to 140°C and a heating rate of 5. Dynamic viscoelasticity measurements are performed at °C/min, frequency of 10 Hz, and strain of 0.08%.
上記粘着剤層の８０℃における貯蔵弾性率Ｇ’（８０℃）の好ましい下限は１．０×１０４Ｐａである。上記粘着剤層の貯蔵弾性率Ｇ’（８０℃）が１．０×１０４Ｐａ以上であることにより、上記粘着剤層の高温におけるバルクの凝集力がより大きくなり、高温における耐クリープ性や高温耐反発性により優れるものとなる。上記粘着剤層の貯蔵弾性率Ｇ’（８０℃）のより好ましい下限は１．５×１０４Ｐａ、更に好ましい下限は２．０×１０４Ｐａ、更により好ましい下限は５．０×１０４Ｐａ、特に好ましい下限は８．０×１０４Ｐａである。
上記粘着剤層の貯蔵弾性率Ｇ’（８０℃）が高すぎると常温における貯蔵弾性率も高くなり、粗面に対する接着力が低下することから、上記粘着剤層の貯蔵弾性率Ｇ’（８０℃）の好ましい上限は２．０×１０５Ｐａである。 A preferable lower limit of the storage modulus G' (80°C) of the adhesive layer at 80°C is 1.0×10 4 Pa. By setting the storage elastic modulus G' (80°C) of the adhesive layer to be 1.0×10 4 Pa or more, the bulk cohesive force of the adhesive layer at high temperatures becomes greater, and the creep resistance at high temperatures and It has better high-temperature repulsion resistance. A more preferable lower limit of the storage elastic modulus G' (80° C.) of the adhesive layer is 1.5×10 4 Pa, an even more preferable lower limit is 2.0×10 4 Pa, and an even more preferable lower limit is 5.0×10 4 Pa, a particularly preferable lower limit is 8.0×10 4 Pa.
If the storage elastic modulus G' (80°C) of the adhesive layer is too high, the storage elastic modulus at room temperature will also be high and the adhesive force to rough surfaces will decrease. C) is preferably 2.0×10 5 Pa.
上記粘着剤層の厚みの好ましい下限は１０μｍ、好ましい上限は１００μｍである。上記粘着剤層の厚みが１０μｍ以上であることにより、上記粘着剤層の被着体への食い込み性が増し、剥離抵抗が大きくなるため、粗面に対する接着性により優れるものとなる。上記厚みが１００μｍ以下であることにより、上記粘着剤層にせん断力が加わった場合のズレ量が減るため、上記粘着剤層が保持性能により優れるものとなる。上記粘着剤層の厚みのより好ましい下限は１２μｍ、更に好ましい下限は１５μｍであり、より好ましい上限は６０μｍ、更に好ましい上限は５０μｍである。 The preferable lower limit of the thickness of the adhesive layer is 10 μm, and the preferable upper limit is 100 μm. When the thickness of the adhesive layer is 10 μm or more, the ability of the adhesive layer to penetrate into the adherend increases, and the peeling resistance increases, resulting in better adhesion to rough surfaces. When the thickness is 100 μm or less, the amount of displacement when a shearing force is applied to the adhesive layer is reduced, so that the adhesive layer has better retention performance. A more preferable lower limit of the thickness of the adhesive layer is 12 μm, an even more preferable lower limit is 15 μm, a more preferable upper limit is 60 μm, and an even more preferable upper limit is 50 μm.
前記粘着テープは、基材を有することが好ましい。
上記基材としては、樹脂フィルムが好ましい。
上記樹脂フィルムとしては、ポリエステル樹脂フィルム又はポリプロピレン樹脂フィルムが好ましい。なかでも、平坦であり、厚みのぶれが小さく、強度が高いことから、ポリエステル樹脂フィルムが好ましく、ポリエステル樹脂フィルムのなかでは、ポリエチレンテレフタレートフィルムがより好ましい。 It is preferable that the adhesive tape has a base material.
As the base material, a resin film is preferable.
The resin film is preferably a polyester resin film or a polypropylene resin film. Among these, polyester resin films are preferred because they are flat, have small thickness fluctuations, and have high strength. Among polyester resin films, polyethylene terephthalate films are more preferred.
上記基材は、その物性を損なわない範囲内において、充填剤、紫外線吸収剤、光安定剤、帯電防止剤等の添加剤を含有していてもよい。 The base material may contain additives such as a filler, an ultraviolet absorber, a light stabilizer, and an antistatic agent within a range that does not impair its physical properties.
上記基材の厚みは、用途に合わせて適宜選択されるが、好ましい下限は５μｍ、好ましい上限は２００μｍである。上記基材の厚みが２００μｍ以下であることにより、電子部材の固定用途での使用に適したものとなり、かつ、製造時のＣＯ２排出量を低減することができる。上記基材の厚みのより好ましい下限は１０μｍ、更に好ましい下限は１５μｍであり、より好ましい上限は１００μｍ、更に好ましい上限は５０μｍである。 The thickness of the above-mentioned base material is appropriately selected depending on the intended use, and the preferable lower limit is 5 μm and the preferable upper limit is 200 μm. When the thickness of the base material is 200 μm or less, it becomes suitable for use in fixing electronic components, and it is possible to reduce CO 2 emissions during manufacturing. A more preferable lower limit of the thickness of the base material is 10 μm, an even more preferable lower limit is 15 μm, a more preferable upper limit is 100 μm, and an even more preferable upper limit is 50 μm.
本発明の粘着テープは、上記基材の一方の面のみに上記粘着剤層を有していてもよいし、上記基材の両面に上記粘着剤層を有していてもよい。なかでも、上記基材の両面に上記粘着剤層を有することが好ましい。 The adhesive tape of the present invention may have the adhesive layer on only one side of the base material, or may have the adhesive layer on both sides of the base material. Among these, it is preferable to have the adhesive layer on both sides of the base material.
本発明の粘着テープの製造方法は特に限定されず、例えば、上記基材の両面に同じ組成、厚みの粘着剤層を有する場合、以下の方法が挙げられる。
まず、（メタ）アクリル共重合体、架橋剤、粘着付与樹脂、及び、溶剤や必要に応じて用いられる他の成分を含む粘着剤を調製する。次いで、一面が離型処理された離型フィルムの離型処理面に上記で得られた粘着剤を塗布して乾燥させて、離型フィルムの離型処理面に粘着剤層を有する積層シートを作製する。同様の要領で積層シートを合計２個作製する。次いで、２個の積層シートの粘着剤層を基材に転写及び積層一体化させて、基材の両面に粘着剤層を有する粘着シートを得る。 The method for producing the adhesive tape of the present invention is not particularly limited, and for example, when the base material has adhesive layers having the same composition and thickness on both sides, the following method may be used.
First, an adhesive containing a (meth)acrylic copolymer, a crosslinking agent, a tackifying resin, a solvent, and other components used as necessary is prepared. Next, the adhesive obtained above is applied to the release-treated side of the release film, one side of which has been subjected to the release treatment, and dried to form a laminated sheet having an adhesive layer on the release-treated side of the release film. Create. A total of two laminated sheets are prepared in the same manner. Next, the pressure-sensitive adhesive layers of the two laminated sheets are transferred to the base material and laminated together to obtain a pressure-sensitive adhesive sheet having pressure-sensitive adhesive layers on both sides of the base material.
本発明の粘着テープの保持性能と接着性とを双方とも高める観点から、本発明の粘着テープは高温耐反発性に優れることが好ましい。
なお、高温耐反発性は、例えば、以下の方法等で評価することができる。また、図２に高温耐反発性試験の方法を示す模式図を示す。
即ち、本発明の粘着テープ１を２５ｍｍ幅×長さ３００ｍｍの短冊状に裁断した後、測定しない側の粘着剤層をＰＥＴフィルム４（厚さ１００μｍ、２５ｍｍ幅、長さ３００ｍｍ）と貼り合わせる。次いで、測定する側の粘着剤層をＳＵＳ板２（エタノールで洗浄後乾拭きしたＳＵＳ３０４板）に、粘着テープ１の短辺をＳＵＳ板の１辺と重なるように貼り合わせた後、２ｋｇのゴムローラーを３００ｍｍ／ｍｉｎの速度で５往復させることで圧着した後、２３℃で７２時間静置し試験片を作製する。作製した試験片について、更に、８０℃のオーブンに入れて１５分間加熱した後、８０℃の条件下で、水平方向に設置した試験片に対して、試験片の先端に１００ｇの重り５を用いて１００ｇの荷重を試験片と垂直方向になるように加えた状態を１４４時間保持する高温耐反発性試験を行う。粘着テープ全体が落下した場合は１００ｇの荷重を加えた時間を０時間とした落下時間を測定し、粘着テープ全体が落下しなかった場合は粘着テープが剥離した剥離長さ（図２における双頭矢印間の長さ）を目視にて測定する。当該高温耐反発性試験の結果が、粘着テープ全体が落下せず、かつ、剥離長さが６０ｍｍ以下である場合に、本発明の粘着テープは高温耐反発性に優れるものとなる。 From the viewpoint of improving both the retention performance and adhesiveness of the adhesive tape of the present invention, it is preferable that the adhesive tape of the present invention has excellent high-temperature repulsion resistance.
Note that high-temperature repulsion resistance can be evaluated, for example, by the following method. Further, FIG. 2 shows a schematic diagram showing the method of high temperature repulsion resistance test.
That is, after cutting the adhesive tape 1 of the present invention into a strip shape of 25 mm width x 300 mm length, the adhesive layer on the side not to be measured is pasted to a PET film 4 (thickness 100 μm, 25 mm width, length 300 mm). Next, the adhesive layer on the side to be measured was attached to the SUS plate 2 (SUS304 plate washed with ethanol and wiped dry) so that the short side of the adhesive tape 1 overlapped with one side of the SUS plate, and then a 2 kg rubber roller was attached. After crimping by making 5 reciprocations at a speed of 300 mm/min, the test pieces were prepared by standing at 23° C. for 72 hours. The prepared test piece was further heated in an oven at 80°C for 15 minutes, and then a 100g weight 5 was placed on the tip of the test piece at 80°C for the test piece placed horizontally. A high temperature repulsion resistance test is conducted in which a load of 100 g is applied perpendicularly to the test piece and maintained for 144 hours. If the entire adhesive tape has fallen, measure the falling time with the time when a load of 100g is applied as 0 hours, and if the entire adhesive tape has not fallen, measure the peeling length of the adhesive tape (double-headed arrow in Figure 2). Visually measure the length between the two. If the result of the high-temperature repulsion resistance test is that the entire adhesive tape does not fall and the peeling length is 60 mm or less, the adhesive tape of the present invention has excellent high-temperature repulsion resistance.
本発明によれば、分子量の低い（メタ）アクリル共重合体を用いながらも、保持性能及び接着性に優れる粘着剤層を有する粘着テープを提供することができる。 According to the present invention, it is possible to provide a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer having excellent retention performance and adhesiveness even though it uses a (meth)acrylic copolymer having a low molecular weight.
保持試験の方法を示す模式図である。It is a schematic diagram showing the method of a retention test. 高温耐反発性試験の方法を示す模式図である。FIG. 2 is a schematic diagram showing a method of high temperature repulsion resistance test.
以下に実施例を掲げて本発明の態様を更に詳しく説明するが、本発明はこれら実施例のみに限定されない。 The embodiments of the present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to these Examples.
（アクリル共重合体Ａ～Ｓの調製）
温度計、撹拌機、冷却管を備えた反応器内に、表１に示す溶剤を加え、窒素置換した後、反応器を加熱して還流を開始した。溶剤が沸騰してから、表１に示す重合開始剤１を投入した後、表１に示すモノマーと連鎖移動剤との混合溶液を滴下漏斗から反応器内に２時間かけて滴下した。その後、更に表１に示す重合開始剤２を投入し、滴下を開始した時間を重合開始時間とし、重合開始から合計６時間重合反応を行い、アクリル共重合体Ａ～Ｓを含有する溶液を得た。
なお、表１中における各材料は以下の通りである。
　ＢＡ：ブチルアクリレート
　２ＥＨＡ：２－エチルヘキシルアクリレート
　Ｃ７：ｎ－ヘプチルアクリレート
　ＨＥＡ：ヒドロキシエチルアクリレート
　Ａａｃ：アクリル酸
　ＡＩＢＮ：２，２’－アゾビス（イソブチロニトリル） (Preparation of acrylic copolymers A to S)
The solvent shown in Table 1 was added to a reactor equipped with a thermometer, a stirrer, and a cooling tube, and after the atmosphere was replaced with nitrogen, the reactor was heated to start reflux. After the solvent boiled, the polymerization initiator 1 shown in Table 1 was added, and then a mixed solution of the monomers and chain transfer agent shown in Table 1 was dropped into the reactor from the dropping funnel over 2 hours. Thereafter, the polymerization initiator 2 shown in Table 1 was further added, and the time when dropping started was taken as the polymerization start time, and the polymerization reaction was carried out for a total of 6 hours from the start of polymerization to obtain a solution containing acrylic copolymers A to S. Ta.
In addition, each material in Table 1 is as follows.
BA: Butyl acrylate 2EHA: 2-ethylhexyl acrylate C7: n-heptyl acrylate HEA: Hydroxyethyl acrylate Aac: Acrylic acid AIBN: 2,2'-azobis(isobutyronitrile)
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
（実施例１～２３、比較例１～８）
（１）粘着剤の調製
得られたアクリル共重合体Ａ～Ｓを含有する溶液に、表２、３に示した組成にて各材料を添加し、撹拌して、粘着剤を得た。得られた粘着剤における、固形分中の水酸基を有する化合物の含有割合、及び、固形分中のカルボキシ基を有する化合物の含有割合を表２、３に示した。
なお、表２、３中における各材料は以下の通りである。
　コロネートＬ４５：イソシアネート系架橋剤（東ソー社製）
　ＫＥ３８８：水添ロジンエステル樹脂（荒川化学工業社製、水酸基価４５ｍｇＫＯＨ／ｇ、軟化温度１５０℃）
　ＫＥ３５９：水添ロジンエステル樹脂（荒川化学工業社製、水酸基価４０ｍｇＫＯＨ／ｇ、軟化温度１００℃）
　Ｄ１３５：重合ロジンエステル樹脂（荒川化学工業社製、水酸基価４０ｍｇＫＯＨ／ｇ、軟化温度１３５℃）
　Ｇ１５０：テルペン系樹脂（ヤスハラケミカル社製、水酸基価１００ｍｇＫＯＨ／ｇ、軟化温度１５０℃） (Examples 1 to 23, Comparative Examples 1 to 8)
(1) Preparation of Pressure-Sensitive Adhesives Each material was added to the solution containing the obtained acrylic copolymers A to S in the composition shown in Tables 2 and 3, and stirred to obtain pressure-sensitive adhesives. The content of the compound having a hydroxyl group in the solid content and the content of the compound having a carboxyl group in the solid content of the obtained pressure-sensitive adhesives are shown in Tables 2 and 3.
The materials in Tables 2 and 3 are as follows:
Coronate L45: isocyanate-based crosslinking agent (manufactured by Tosoh Corporation)
KE388: Hydrogenated rosin ester resin (manufactured by Arakawa Chemical Industries, Ltd., hydroxyl value 45 mgKOH/g, softening temperature 150° C.)
KE359: Hydrogenated rosin ester resin (manufactured by Arakawa Chemical Industries, Ltd., hydroxyl value 40 mgKOH/g, softening temperature 100° C.)
D135: Polymerized rosin ester resin (manufactured by Arakawa Chemical Industries, Ltd., hydroxyl value 40 mgKOH/g, softening temperature 135° C.)
G150: Terpene resin (manufactured by Yasuhara Chemical Co., Ltd., hydroxyl value 100 mg KOH/g, softening temperature 150° C.)
（２）粘着テープの作製
一面が離型処理されたポリエチレンテレフタレートフィルムを用意した。このポリエチレンテレフタレートフィルムの離型処理面に上記「（１）粘着剤の調製」で得られた粘着剤を塗布し、１１０℃で５分間乾燥させて、粘着剤中の（メタ）アクリル共重合体の架橋を進行させ、ポリエチレンテレフタレートフィルムの離型処理面に粘着剤層を有する積層シートを作製した。同様にして積層シートを更にもう１個作製し、合計２個の上記積層シートを得た。
次に、基材としてポリエチレンテレフタレートフィルム（厚み２５μｍ）を用意した。この基材の一方側の表面に、一方の積層シートを粘着剤層面から積層して粘着剤層を基材に転写及び積層一体化させた。基材の他方側の表面にもう一方の積層シートを粘着剤層面から積層して粘着剤層を基材に転写及び積層一体化させた。これにより、基材の両面に表２、３に示した厚みを有する粘着剤層が設けられた両面粘着テープを得た。 (2) Preparation of Adhesive Tape A polyethylene terephthalate film, one side of which had been subjected to mold release treatment, was prepared. The adhesive obtained in "(1) Preparation of adhesive" above was applied to the release-treated surface of this polyethylene terephthalate film, and dried at 110°C for 5 minutes to release the (meth)acrylic copolymer in the adhesive. A laminated sheet having an adhesive layer on the release-treated surface of the polyethylene terephthalate film was produced. Another laminated sheet was produced in the same manner, resulting in a total of two laminated sheets.
Next, a polyethylene terephthalate film (thickness: 25 μm) was prepared as a base material. One of the laminated sheets was laminated on one surface of this base material from the adhesive layer side, so that the adhesive layer was transferred and laminated onto the base material. The other laminated sheet was laminated on the other surface of the base material from the pressure-sensitive adhesive layer side, so that the pressure-sensitive adhesive layer was transferred and laminated onto the base material. Thereby, a double-sided adhesive tape was obtained in which adhesive layers having the thicknesses shown in Tables 2 and 3 were provided on both sides of the base material.
（アルカリ分解により得た（メタ）アクリル共重合体の重量平均分子量（Ｍｗ共重合体）、ピークトップ分子量（Ｍｐ共重合体）、及び、多分散度（Ｍｗ共重合体／Ｍｎ共重合体））
得られた両面粘着テープから粘着剤層３００ｍｇを採取した。圧力容器に採取した上記粘着剤層、エタノール６ｍＬ、６０％ＫＯＨ水溶液７ｍＬを加え、１６０℃のオーブンで６０時間加圧加水分解することにより、粘着剤層中の架橋生成物の架橋点をアルカリ分解し、（メタ）アクリル共重合体を得た。
得られた（メタ）アクリル共重合体について、ゲルパーミエーションクロマトグラフィー（ＧＰＣ）（Ｗａｔｅｒｓ社製、「２６９０　Ｓｅｐａｒａｔｉｏｎｓ　Ｍｏｄｅｌ」）による分析を行い、ポリスチレン換算による分子量分布を測定した。得られた分子量分布から導出された、アルカリ分解により得た（メタ）アクリル共重合体の重量平均分子量（Ｍｗ共重合体）、ピークトップ分子量（Ｍｐ共重合体）、及び、多分散度（Ｍｗ共重合体／Ｍｎ共重合体）を表２、３に示した。上記ＧＰＣは、以下の条件で行った。
　溶離液：テトラヒドロフラン（ＴＨＦ）
　流量：０．４ｍＬ／ｍｉｎ
　検出器：示差屈折計ＲＩ
　カラム：ＬＦ－８０４（ＳＨＯＫＯ社製）
　カラム温度（測定温度）：４０℃
　注入量：２０μＬ (Weight average molecular weight (Mw copolymer), peak top molecular weight (Mp copolymer), and polydispersity (Mw copolymer/Mn copolymer) of (meth)acrylic copolymer obtained by alkaline decomposition )
300 mg of the adhesive layer was collected from the obtained double-sided adhesive tape. The above adhesive layer collected in a pressure vessel, 6 mL of ethanol, and 7 mL of 60% KOH aqueous solution were added, and the crosslinking points of the crosslinked product in the adhesive layer were alkali-decomposed by pressurized hydrolysis in an oven at 160°C for 60 hours. A (meth)acrylic copolymer was obtained.
The obtained (meth)acrylic copolymer was analyzed by gel permeation chromatography (GPC) (manufactured by Waters, "2690 Separations Model") to measure the molecular weight distribution in terms of polystyrene. The weight average molecular weight (Mw copolymer), peak top molecular weight (Mp copolymer), and polydispersity (Mw copolymer/Mn copolymer) are shown in Tables 2 and 3. The above GPC was performed under the following conditions.
Eluent: Tetrahydrofuran (THF)
Flow rate: 0.4mL/min
Detector: Differential refractometer RI
Column: LF-804 (manufactured by SHOKO)
Column temperature (measurement temperature): 40°C
Injection volume: 20μL
（ゾル成分の重量平均分子量（Ｍｗゾル）、及び、Ｍｗゾル－Ｍｗ共重合体）
得られた両面粘着テープの粘着剤層をテトラヒドロフラン（ＴＨＦ）中に２３℃にて２４時間浸漬し、不溶解分を２００メッシュの金網で濾過して取り除くことで、粘着剤層のゾル成分を得た。
得られた粘着剤層のゾル成分について、ゲルパーミエーションクロマトグラフィー（ＧＰＣ）（Ｗａｔｅｒｓ社製、「２６９０　Ｓｅｐａｒａｔｉｏｎｓ　Ｍｏｄｅｌ」）による分析を行い、ポリスチレン換算による分子量分布を測定した。得られた分子量分布から導出されたゾル成分の重量平均分子量（Ｍｗゾル）、及び、ゾル成分の重量平均分子量から、アルカリ分解により得た（メタ）アクリル共重合体の重量平均分子量を差し引いた値（Ｍｗゾル－Ｍｗ共重合体）を表２、３に示した。上記ＧＰＣは、以下の条件で行った。
　溶離液：テトラヒドロフラン（ＴＨＦ）
　流量：０．４ｍＬ／ｍｉｎ
　検出器：示差屈折計ＲＩ
　カラム：ＬＦ－８０４（ＳＨＯＫＯ社製）
　カラム温度（測定温度）：４０℃
　注入量：２０μＬ (Weight average molecular weight of sol component (Mw sol) and Mw sol-Mw copolymer)
The adhesive layer of the obtained double-sided adhesive tape was immersed in tetrahydrofuran (THF) at 23°C for 24 hours, and the insoluble matter was removed by filtering through a 200 mesh wire mesh to obtain the sol component of the adhesive layer. Ta.
The sol component of the obtained adhesive layer was analyzed by gel permeation chromatography (GPC) (manufactured by Waters, "2690 Separations Model"), and the molecular weight distribution in terms of polystyrene was measured. The weight average molecular weight (Mw sol) of the sol component derived from the obtained molecular weight distribution, and the value obtained by subtracting the weight average molecular weight of the (meth)acrylic copolymer obtained by alkaline decomposition from the weight average molecular weight of the sol component. (Mw sol-Mw copolymer) are shown in Tables 2 and 3. The above GPC was performed under the following conditions.
Eluent: Tetrahydrofuran (THF)
Flow rate: 0.4mL/min
Detector: Differential refractometer RI
Column: LF-804 (manufactured by SHOKO)
Column temperature (measurement temperature): 40°C
Injection volume: 20μL
（粘着剤層のゲル分率）
得られた両面粘着テープの粘着剤層をＷ１（ｇ）採取し、採取した上記粘着剤層を酢酸エチル中に２３℃にて２４時間浸漬し、不溶解分を２００メッシュの金網で濾過した。この金網上の残渣を１１０℃にて加熱乾燥し、得られた乾燥残渣の質量Ｗ２（ｇ）を測定した。得られたＷ１及びＷ２から、下記式（Ｉ）によりゲル分率（架橋度）を算出した。得られたゲル分率を表２、３に示した。
　ゲル分率（質量％）＝１００×Ｗ２／Ｗ１　（Ｉ） (Gel fraction of adhesive layer)
W 1 (g) of the adhesive layer of the obtained double-sided adhesive tape was collected, and the collected adhesive layer was immersed in ethyl acetate at 23°C for 24 hours, and the insoluble matter was filtered through a 200 mesh wire mesh. . The residue on the wire mesh was dried by heating at 110° C., and the mass W 2 (g) of the obtained dried residue was measured. From the obtained W 1 and W 2 , the gel fraction (crosslinking degree) was calculated using the following formula (I). The gel fractions obtained are shown in Tables 2 and 3.
Gel fraction (mass%) = 100 x W 2 /W 1 (I)
（粘着剤層の貯蔵弾性率Ｇ’（８０℃）及びガラス転移温度）
得られた両面粘着テープの粘着剤層を重ね合わせ、厚み１ｍｍ程度の積層体を作製し、６ｍｍ×１０ｍｍに裁断して試験片を得た。得られた試験片について、動的粘弾性測定装置（アイティー計測制御社、「ＤＶＡ－２００」）を用い、せん断モードにて窒素雰囲気下、測定温度－４０℃～１４０℃、昇温速度５℃／ｍｉｎ、周波数１０Ｈｚ、ひずみ０．０８％で動的粘弾性測定を行い、８０℃における貯蔵弾性率Ｇ’（８０℃）を得た。また、動的粘弾性測定により得られた損失正接（ｔａｎδ）の極大のうち、ミクロブラウン運動に起因する極大が現れた温度をガラス転移温度とした。得られた貯蔵弾性率Ｇ’（８０℃）及びガラス転移温度を表２、３に示した。 (Storage modulus G' (80°C) and glass transition temperature of adhesive layer)
The adhesive layers of the obtained double-sided adhesive tapes were overlapped to produce a laminate with a thickness of about 1 mm, and the laminate was cut into a size of 6 mm x 10 mm to obtain a test piece. The obtained test piece was measured using a dynamic viscoelasticity measuring device (IT Keizai Control Co., Ltd., "DVA-200") under a nitrogen atmosphere in shear mode at a measurement temperature of -40°C to 140°C and a heating rate of 5. Dynamic viscoelasticity was measured at a temperature of 10° C./min, a frequency of 10 Hz, and a strain of 0.08%, and the storage modulus G′ (80° C.) was obtained. Further, among the maximum loss tangents (tan δ) obtained by dynamic viscoelasticity measurement, the temperature at which the maximum due to micro-Brownian motion appeared was defined as the glass transition temperature. The obtained storage modulus G' (80° C.) and glass transition temperature are shown in Tables 2 and 3.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
＜評価＞
実施例、比較例で得られた粘着剤及び両面粘着テープについて以下の評価を行った。結果を表４、５に示した。 <Evaluation>
The adhesives and double-sided adhesive tapes obtained in Examples and Comparative Examples were evaluated as follows. The results are shown in Tables 4 and 5.
（加工性）                                   
得られた粘着剤について、固形分濃度を６０質量％に調整し、Ｂ型粘度計（英弘精機社製、「ＲＶＤＶ－２＋ＰＲＯ」）及びスピンドルＳ０４を用いて、２３℃、１２ｒｐｍの条件で粘度を測定した。また、固形分濃度を７０質量％に調整した粘着剤についても、同様にして粘度を測定した
得られた粘度が１万ｍＰａ・ｓ以下であった場合を「○」、１万ｍＰａ・ｓを超えた場合を「×」として、加工性を評価した。 (Workability)
The solid content concentration of the obtained adhesive was adjusted to 60% by mass, and the viscosity was measured at 23°C and 12 rpm using a B-type viscometer (manufactured by Hideko Seiki Co., Ltd., "RVDV-2+PRO") and spindle S04. It was measured. In addition, for the adhesive whose solid content concentration was adjusted to 70% by mass, the viscosity was measured in the same way, and if the obtained viscosity was 10,000 mPa・s or less, it was marked “○”, and 10,000 mPa・s The workability was evaluated by marking the case as "×" when the value exceeded.
（保持性能）
得られた両面粘着テープを２５ｍｍ幅の短冊状に裁断した後、ＳＵＳ板（エタノールで洗浄後乾拭きしたＳＵＳ３０４板）に、２ｋｇのゴムローラーを３００ｍｍ／ｍｉｎの速度で一往復させることで貼り合わせた。次いで、接着面積が２５ｍｍ×２５ｍｍとなるように、粘着テープに切り込みを入れた。その後、２３℃で２０分間静置してから、８０℃のオーブンに入れ、更に１５分間加熱した後に、８０℃に保持しながら、図１に示すように１ｋｇの重り３を用いて１ｋｇの荷重をせん断方向に加えた。粘着テープの落下の有無を確認し、２４時間経過しても落下しなかった場合は、切り込み位置からの移動量（ズレ）をスケールルーペで測定した。
粘着テープが落下せず、ズレが１ｍｍ以下であった場合を「○」、粘着テープが落下せず、ズレが１ｍｍを超えた場合を「△」、粘着テープが落下した場合を「×」として、保持性能を評価した。 (retention performance)
The resulting double-sided adhesive tape was cut into strips with a width of 25 mm, and then bonded to a SUS board (SUS304 board that had been washed with ethanol and wiped dry) by moving a 2 kg rubber roller back and forth at a speed of 300 mm/min. . Next, cuts were made in the adhesive tape so that the adhesive area was 25 mm x 25 mm. After that, it was left to stand at 23°C for 20 minutes, then placed in an oven at 80°C, heated for another 15 minutes, and then, while being maintained at 80°C, a 1kg weight was applied using a 1kg weight 3 as shown in Figure 1. was added in the shear direction. It was checked whether or not the adhesive tape had fallen, and if it had not fallen after 24 hours, the amount of movement (shift) from the incision position was measured using a scale loupe.
If the adhesive tape did not fall and the deviation was 1 mm or less, it was marked as "○." If the adhesive tape did not fall and the deviation exceeded 1 mm, it was marked as "△." If the adhesive tape fell, it was marked as "x." , the retention performance was evaluated.
（接着性）
粘着テープを２５ｍｍ幅の短冊状に裁断した後、ＳＵＳ板（エタノールで洗浄後乾拭きしたＳＵＳ３０４板）に、２ｋｇのゴムローラーを３００ｍｍ／ｍｉｎの速度で一往復させることで貼り合わせた。次いで、温度２３℃、相対湿度５０％にて２０分間静置することにより試験片を得た。得られた試験片について、引張試験機（エー・アンド・デイ社製、「ＲＴＩ－１３１０」）を用いてＪＩＳ　Ｚ０２３７に準拠して、２３℃、剥離速度３００ｍｍ／ｍｉｎ、剥離角度１８０°の条件で引張試験を行い、１８０°引きはがし粘着力を測定した。
得られた１８０°引きはがし粘着力が１８Ｎ／２５ｍｍ以上であった場合を「○」、１５Ｎ／２５ｍｍ以上１８Ｎ／２５ｍｍ未満であった場合を「△」、１５Ｎ／２５ｍｍ未満であった場合を「×」として、接着性を評価した。
また、ＳＵＳ板（エタノールで洗浄後乾拭きしたＳＵＳ３０４板）に代えて粗面ＳＵＳ板を用い、同様にして１８０°引きはがし粘着力を測定した。上記粗面ＳＵＳ板は、エタノールで洗浄後乾拭きしたＳＵＳ３０４板を、粒度８０の研磨紙で磨いたものである。また、粗面ＳＵＳ板の表面をレーザー顕微鏡によって観察した結果、Ｒａが１．７μｍ、Ｒｚが１０μｍであった。 (Adhesiveness)
The adhesive tape was cut into strips with a width of 25 mm, and then bonded to an SUS board (SUS304 board washed with ethanol and wiped dry) by moving a 2 kg rubber roller back and forth at a speed of 300 mm/min. Next, a test piece was obtained by allowing it to stand for 20 minutes at a temperature of 23° C. and a relative humidity of 50%. The obtained test piece was tested in accordance with JIS Z0237 using a tensile tester (manufactured by A&D Co., Ltd., "RTI-1310") at a temperature of 23°C, a peeling rate of 300 mm/min, and a peeling angle of 180°. A tensile test was conducted and the 180° peeling adhesive strength was measured.
If the obtained 180° peeling adhesive force was 18N/25mm or more, "○", if it was 15N/25mm or more and less than 18N/25mm, "△", if it was less than 15N/25mm, " Adhesion was evaluated as "x".
Furthermore, a rough surface SUS board was used instead of the SUS board (an SUS304 board that had been cleaned with ethanol and then wiped dry), and the 180° peeling strength was measured in the same manner. The above-mentioned rough-surfaced SUS board is a SUS304 board that has been cleaned with ethanol and wiped dry, and then polished with abrasive paper having a grain size of 80. Further, as a result of observing the surface of the rough SUS plate using a laser microscope, Ra was 1.7 μm and Rz was 10 μm.
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000005
本発明によれば、分子量の低い（メタ）アクリル共重合体を用いながらも、保持性能及び接着性に優れる粘着剤層を有する粘着テープを提供することができる。 According to the present invention, it is possible to provide a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer having excellent retention performance and adhesiveness even though it uses a (meth)acrylic copolymer having a low molecular weight.
１　粘着テープ
２　ＳＵＳ板
３　１ｋｇの荷重（重り）
４　ＰＥＴフィルム
５　１００ｇの荷重（重り） 1 Adhesive tape 2 SUS board 3 1kg load (weight)
4 PET film 5 100g load (weight)

Claims (18)

  1. 粘着剤層を有する粘着テープであって、
    前記粘着剤層は、（メタ）アクリル共重合体と架橋剤と粘着付与樹脂とを含む粘着剤の架橋生成物を含有し、
    前記架橋生成物の架橋点のアルカリ分解により得た（メタ）アクリル共重合体について示差屈折計ＲＩ検出によるＧＰＣ測定を行った際の、分子量５０００以上の領域における該（メタ）アクリル共重合体の重量平均分子量が８万以上５０万未満であり、
    ＳＵＳ板と貼り合わせた前記粘着テープについて、８０℃におけるせん断方向に１ｋｇ荷重を２４時間加える保持試験において該粘着テープが落下しない、かつ、
    ＳＵＳ板に対する該粘着テープの１８０°引きはがし粘着力が１５Ｎ／２５ｍｍ以上である
    ことを特徴とする粘着テープ。     An adhesive tape having an adhesive layer,
    The adhesive layer contains a crosslinked product of an adhesive containing a (meth)acrylic copolymer, a crosslinking agent, and a tackifying resin,
    When the (meth)acrylic copolymer obtained by alkaline decomposition of the crosslinking point of the crosslinked product was subjected to GPC measurement using differential refractometer RI detection, the (meth)acrylic copolymer in the molecular weight region of 5000 or more was The weight average molecular weight is 80,000 or more and less than 500,000,
    Regarding the adhesive tape bonded to the SUS board, the adhesive tape does not fall in a holding test in which a 1 kg load is applied in the shear direction at 80 ° C. for 24 hours, and
    An adhesive tape having a 180° peeling adhesive strength of 15 N/25 mm or more to an SUS plate.
  2. 粘着剤層を有する粘着テープであって、
    前記粘着剤層は、（メタ）アクリル共重合体と架橋剤と粘着付与樹脂とを含む粘着剤の架橋生成物を含有し、
    前記架橋生成物の架橋点のアルカリ分解により得た（メタ）アクリル共重合体について示差屈折計ＲＩ検出によるＧＰＣ測定を行った際の、分子量５０００以上の領域における該（メタ）アクリル共重合体の重量平均分子量が８万以上５０万未満であり、かつ、
    下記第一の構成、下記第二の構成、又は、下記第三の構成を満たす
    ことを特徴とする粘着テープ。
    第一の構成：前記粘着剤は、前記（メタ）アクリル共重合体１００質量部に対して前記架橋剤を６質量部以上含み、かつ、前記粘着剤層のゲル分率が５質量％以上である
    第二の構成：前記粘着剤は、前記（メタ）アクリル共重合体１００質量部に対して前記架橋剤を６質量部以上含み、前記粘着剤層のゲル分率が５質量％未満であり、かつ、前記粘着剤層のゾル成分について示差屈折計ＲＩ検出によるＧＰＣ測定を行った際の、分子量５０００以上の領域における該ゾル成分の重量平均分子量から、前記架橋生成物の架橋点のアルカリ分解により得た（メタ）アクリル共重合体について示差屈折計ＲＩ検出によるＧＰＣ測定を行った際の、分子量５０００以上の領域における該（メタ）アクリル共重合体の重量平均分子量を差し引いた値が８万以上である
    第三の構成：前記粘着剤は、前記（メタ）アクリル共重合体１００質量部に対して前記架橋剤を０．１質量部以上６質量部未満含み、かつ、前記粘着剤層のゲル分率が３０質量％を超える     An adhesive tape having an adhesive layer,
    The adhesive layer contains a crosslinked product of an adhesive containing a (meth)acrylic copolymer, a crosslinking agent, and a tackifying resin,
    When the (meth)acrylic copolymer obtained by alkaline decomposition of the crosslinking point of the crosslinked product was subjected to GPC measurement using differential refractometer RI detection, the (meth)acrylic copolymer in the molecular weight region of 5000 or more was The weight average molecular weight is 80,000 or more and less than 500,000, and
    An adhesive tape characterized by satisfying the following first configuration, the following second configuration, or the following third configuration.
    First configuration: The adhesive contains 6 parts by mass or more of the crosslinking agent based on 100 parts by mass of the (meth)acrylic copolymer, and the gel fraction of the adhesive layer is 5% by mass or more. A second configuration: the adhesive contains 6 parts by mass or more of the crosslinking agent based on 100 parts by mass of the (meth)acrylic copolymer, and the gel fraction of the adhesive layer is less than 5% by mass. , and from the weight average molecular weight of the sol component in the molecular weight region of 5,000 or more when performing GPC measurement using differential refractometer RI detection on the sol component of the adhesive layer, the alkali decomposition of the crosslinking point of the crosslinked product is determined. When the (meth)acrylic copolymer obtained was subjected to GPC measurement using differential refractometer RI detection, the value obtained by subtracting the weight average molecular weight of the (meth)acrylic copolymer in the molecular weight region of 5,000 or more was 80,000. The above third configuration: the adhesive contains 0.1 parts by mass or more and less than 6 parts by mass of the crosslinking agent based on 100 parts by mass of the (meth)acrylic copolymer, and the adhesive layer contains Gel fraction exceeds 30% by mass
  3. 前記第一の構成を満たす、請求項２記載の粘着テープ。 The adhesive tape according to claim 2, which satisfies the first configuration.
  4. 前記第二の構成を満たす、請求項２記載の粘着テープ。 The adhesive tape according to claim 2, which satisfies the second configuration.
  5. 前記第三の構成を満たす、請求項２記載の粘着テープ。 The adhesive tape according to claim 2, which satisfies the third configuration.
  6. 前記粘着剤層は、下記第一の構成、下記第二の構成、又は、下記第三の構成を満たす
    請求項１記載の粘着テープ。
    第一の構成：前記粘着剤は、前記（メタ）アクリル共重合体１００質量部に対して前記架橋剤を６質量部以上含み、かつ、前記粘着剤層のゲル分率が５質量％以上である
    第二の構成：前記粘着剤は、前記（メタ）アクリル共重合体１００質量部に対して前記架橋剤を６質量部以上含み、前記粘着剤層のゲル分率が５質量％未満であり、かつ、前記粘着剤層のゾル成分について示差屈折計ＲＩ検出によるＧＰＣ測定を行った際の、分子量５０００以上の領域における該ゾル成分の重量平均分子量から、前記架橋生成物の架橋点のアルカリ分解により得た（メタ）アクリル共重合体について示差屈折計ＲＩ検出によるＧＰＣ測定を行った際の、分子量５０００以上の領域における該（メタ）アクリル共重合体の重量平均分子量を差し引いた値が８万以上である
    第三の構成：前記粘着剤は、前記（メタ）アクリル共重合体１００質量部に対して前記架橋剤を０．１質量部以上６質量部未満含み、かつ、前記粘着剤層のゲル分率が３０質量％を超える     The adhesive tape according to claim 1, wherein the adhesive layer satisfies the following first configuration, the following second configuration, or the following third configuration.
    First configuration: The adhesive contains 6 parts by mass or more of the crosslinking agent based on 100 parts by mass of the (meth)acrylic copolymer, and the gel fraction of the adhesive layer is 5% by mass or more. A second configuration: the adhesive contains 6 parts by mass or more of the crosslinking agent based on 100 parts by mass of the (meth)acrylic copolymer, and the gel fraction of the adhesive layer is less than 5% by mass. , and from the weight average molecular weight of the sol component in the molecular weight region of 5,000 or more when performing GPC measurement using differential refractometer RI detection on the sol component of the adhesive layer, the alkali decomposition of the crosslinking point of the crosslinked product is determined. When the (meth)acrylic copolymer obtained was subjected to GPC measurement using differential refractometer RI detection, the value obtained by subtracting the weight average molecular weight of the (meth)acrylic copolymer in the molecular weight region of 5,000 or more was 80,000. The above third configuration: the adhesive contains 0.1 parts by mass or more and less than 6 parts by mass of the crosslinking agent based on 100 parts by mass of the (meth)acrylic copolymer, and the adhesive layer contains Gel fraction exceeds 30% by mass
  7. 前記粘着剤層は、前記第一の構成として、前記粘着剤は、前記（メタ）アクリル共重合体１００質量部に対して前記架橋剤を６質量部以上含み、かつ、前記粘着剤層のゲル分率が５質量％以上３０質量％未満である構成を有するか、又は、
    前記第三の構成として、前記粘着剤は、前記（メタ）アクリル共重合体１００質量部に対して前記架橋剤を１．５質量部以上６質量部未満含み、かつ、前記粘着剤層のゲル分率が３０質量％を超える構成を有する
    請求項２又は６記載の粘着テープ。     The adhesive layer has the first configuration, in which the adhesive contains 6 parts by mass or more of the crosslinking agent based on 100 parts by mass of the (meth)acrylic copolymer, and the adhesive layer contains a gel of the adhesive layer. It has a structure in which the fraction is 5% by mass or more and less than 30% by mass, or
    In the third configuration, the adhesive contains 1.5 parts by mass or more and less than 6 parts by mass of the crosslinking agent based on 100 parts by mass of the (meth)acrylic copolymer, and the adhesive layer contains a gel. The adhesive tape according to claim 2 or 6, having a composition in which the fraction exceeds 30% by mass.
  8. 前記粘着剤層は、前記第一の構成として、前記粘着剤は、前記（メタ）アクリル共重合体１００質量部に対して前記架橋剤を６質量部以上含み、かつ、前記粘着剤層のゲル分率が５質量％以上３０質量％未満である構成を有する請求項７記載の粘着テープ。 The adhesive layer has the first configuration, in which the adhesive contains 6 parts by mass or more of the crosslinking agent based on 100 parts by mass of the (meth)acrylic copolymer, and the adhesive layer contains a gel of the adhesive layer. The adhesive tape according to claim 7, having a composition in which the fraction is 5% by mass or more and less than 30% by mass.
  9. 前記粘着剤層は、前記第三の構成として、前記粘着剤は、前記（メタ）アクリル共重合体１００質量部に対して前記架橋剤を１．５質量部以上６質量部未満含み、かつ、前記粘着剤層のゲル分率が３０質量％を超える構成を有する請求項７記載の粘着テープ。 The adhesive layer has the third configuration, wherein the adhesive contains 1.5 parts by mass or more and less than 6 parts by mass of the crosslinking agent based on 100 parts by mass of the (meth)acrylic copolymer, and The adhesive tape according to claim 7, wherein the adhesive layer has a gel fraction of more than 30% by mass.
  10. 前記粘着剤層のゾル成分について示差屈折計ＲＩ検出によるＧＰＣ測定を行った際の、分子量５０００以上の領域における該ゾル成分の重量平均分子量が５万以上５０万以下である請求項１、２、３、４、５、６、７、８又は９記載の粘着テープ。 Claims 1 and 2, wherein the sol component of the adhesive layer has a weight average molecular weight of 50,000 to 500,000 in a molecular weight region of 5,000 or more when GPC measurement is performed using differential refractometer RI detection. The adhesive tape according to 3, 4, 5, 6, 7, 8 or 9.
  11. 前記架橋生成物の架橋点のアルカリ分解により得た（メタ）アクリル共重合体について示差屈折計ＲＩ検出によるＧＰＣ測定を行った際の、分子量５０００以上の領域における該（メタ）アクリル共重合体のピークトップ分子量が７万以上３０万以下である請求項１、２、３、４、５、６、７、８、９又は１０記載の粘着テープ。 When the (meth)acrylic copolymer obtained by alkaline decomposition of the crosslinking point of the crosslinked product was subjected to GPC measurement using differential refractometer RI detection, the (meth)acrylic copolymer in the molecular weight region of 5000 or more was The adhesive tape according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, having a peak top molecular weight of 70,000 or more and 300,000 or less.
  12. 前記粘着剤は、水酸基を有する化合物を固形分中０．０３質量％以上含み、かつ、カルボキシ基を有する化合物を固形分中２質量％以上含む請求項１、２、３、４、５、６、７、８、９、１０又は１１記載の粘着テープ。 Claims 1, 2, 3, 4, 5, 6, wherein the adhesive contains 0.03% by mass or more of a compound having a hydroxyl group in the solid content, and 2% by mass or more of the compound having a carboxy group in the solid content. , 7, 8, 9, 10 or 11.
  13. 前記（メタ）アクリル共重合体は、炭素数が６以上のアルキル基を有するモノマーに由来する構成単位を５０質量％以上有する請求項１、２、３、４、５、６、７、８、９、１０、１１又は１２記載の粘着テープ。 Claims 1, 2, 3, 4, 5, 6, 7, 8, wherein the (meth)acrylic copolymer has 50% by mass or more of structural units derived from a monomer having an alkyl group having 6 or more carbon atoms. 9, 10, 11 or 12.
  14. 前記粘着剤層は、ガラス転移温度が－１０℃以上３０℃以下である請求項１、２、３、４、５、６、７、８、９、１０、１１、１２又は１３記載の粘着テープ。 The adhesive tape according to claim 1, wherein the adhesive layer has a glass transition temperature of -10°C or more and 30°C or less. .
  15. 前記粘着剤層は、８０℃における貯蔵弾性率Ｇ’（８０℃）が１．０×１０４Ｐａ以上である請求項１、２、３、４、５、６、７、８、９、１０、１１、１２、１３又は１４記載の粘着テープ。 Claims 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, wherein the adhesive layer has a storage modulus G' (80°C) of 1.0 x 10 4 Pa or more. , 11, 12, 13 or 14.
  16. 前記粘着剤層は、厚みが１０μｍ以上１００μｍ以下である請求項１、２、３、４、５、６、７、８、９、１０、１１、１２、１３、１４又は１５記載の粘着テープ。 The adhesive tape according to claim 1, wherein the adhesive layer has a thickness of 10 μm or more and 100 μm or less.
  17. 前記粘着テープは、基材を有し、前記基材は、ポリエステル樹脂フィルム又はポリプロピレン樹脂フィルムであり、かつ、前記基材の厚みが５μｍ以上２００μｍ以下である請求項１、２、３、４、５、６、７、８、９、１０、１１、１２、１３、１４、１５又は１６記載の粘着テープ。 The adhesive tape has a base material, the base material is a polyester resin film or a polypropylene resin film, and the thickness of the base material is 5 μm or more and 200 μm or less, The adhesive tape according to 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 or 16.
  18. 前記粘着テープは、基材を有し、前記基材の両面に前記粘着剤層を有する請求項１、２、３、４、５、６、７、８、９、１０、１１、１２、１３、１４、１５、１６又は１７記載の粘着テープ。 The adhesive tape has a base material, and has the adhesive layer on both sides of the base material. , 14, 15, 16 or 17.
PCT/JP2023/034089 2022-09-21 2023-09-20 Adhesive tape WO2024063092A1 (en)

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JP2022149991 2022-09-21
JP2022-149992 2022-09-21
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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010248465A (en) * 2009-03-26 2010-11-04 Dic Corp Water dispersion type acrylic adhesive composition and adhesive tape
WO2016035747A1 (en) * 2014-09-02 2016-03-10 積水化学工業株式会社 Double-sided adhesive tape for portable electronic device
JP2021020986A (en) * 2019-07-25 2021-02-18 マクセルホールディングス株式会社 Repeelable adhesive composition and adhesive tape
WO2022091395A1 (en) * 2020-10-30 2022-05-05 株式会社寺岡製作所 Adhesive tape

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010248465A (en) * 2009-03-26 2010-11-04 Dic Corp Water dispersion type acrylic adhesive composition and adhesive tape
WO2016035747A1 (en) * 2014-09-02 2016-03-10 積水化学工業株式会社 Double-sided adhesive tape for portable electronic device
JP2021020986A (en) * 2019-07-25 2021-02-18 マクセルホールディングス株式会社 Repeelable adhesive composition and adhesive tape
WO2022091395A1 (en) * 2020-10-30 2022-05-05 株式会社寺岡製作所 Adhesive tape

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