WO2020013168A1 - 粘着シート - Google Patents
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- WO2020013168A1 WO2020013168A1 PCT/JP2019/027108 JP2019027108W WO2020013168A1 WO 2020013168 A1 WO2020013168 A1 WO 2020013168A1 JP 2019027108 W JP2019027108 W JP 2019027108W WO 2020013168 A1 WO2020013168 A1 WO 2020013168A1
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- pressure
- sensitive adhesive
- weight
- adhesive sheet
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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
- 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]
- C09J7/381—Pressure-sensitive adhesives [PSA] based on macromolecular compounds obtained by reactions involving only carbon-to-carbon unsaturated bonds
- C09J7/385—Acrylic polymers
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
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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
- C09J11/08—Macromolecular additives
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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
- 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
- C09J133/02—Homopolymers or copolymers of acids; Metal or ammonium salts thereof
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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
- 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
- C09J133/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, the oxygen atom being present only as part of the carboxyl radical
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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
- 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
- C09J133/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, the oxygen atom being present only as part of the carboxyl radical
- C09J133/08—Homopolymers or copolymers of acrylic acid esters
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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
- 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
- C09J7/26—Porous or cellular plastics
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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
- 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]
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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
- C09J2203/00—Applications of adhesives in processes or use of adhesives in the form of films or foils
- C09J2203/326—Applications of adhesives in processes or use of adhesives in the form of films or foils for bonding electronic components such as wafers, chips or semiconductors
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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
- C09J2301/00—Additional features of adhesives in the form of films or foils
- C09J2301/10—Additional features of adhesives in the form of films or foils characterized by the structural features of the adhesive tape or sheet
- C09J2301/12—Additional features of adhesives in the form of films or foils characterized by the structural features of the adhesive tape or sheet by the arrangement of layers
- C09J2301/122—Additional features of adhesives in the form of films or foils characterized by the structural features of the adhesive tape or sheet by the arrangement of layers the adhesive layer being present only on one side of the carrier, e.g. single-sided adhesive tape
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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
- C09J2301/00—Additional features of adhesives in the form of films or foils
- C09J2301/30—Additional features of adhesives in the form of films or foils characterized by the chemical, physicochemical or physical properties of the adhesive or the carrier
- C09J2301/302—Additional features of adhesives in the form of films or foils characterized by the chemical, physicochemical or physical properties of the adhesive or the carrier the adhesive being pressure-sensitive, i.e. tacky at temperatures inferior to 30°C
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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
- C09J2301/00—Additional features of adhesives in the form of films or foils
- C09J2301/30—Additional features of adhesives in the form of films or foils characterized by the chemical, physicochemical or physical properties of the adhesive or the carrier
- C09J2301/312—Additional features of adhesives in the form of films or foils characterized by the chemical, physicochemical or physical properties of the adhesive or the carrier parameters being the characterizing feature
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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
- C09J2423/00—Presence of polyolefin
- C09J2423/04—Presence of homo or copolymers of ethene
- C09J2423/046—Presence of homo or copolymers of ethene in the substrate
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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
- C09J2433/00—Presence of (meth)acrylic polymer
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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
- C09J2493/00—Presence of natural resin
Definitions
- the present invention relates to an adhesive sheet. Specifically, the present invention relates to a pressure-sensitive adhesive sheet suitable for fixing members constituting a portable device.
- a pressure-sensitive adhesive (also referred to as a pressure-sensitive adhesive; the same applies hereinafter) exhibits a soft solid (viscoelastic body) state in a temperature range around room temperature, and has a property of easily adhering to an adherend by pressure.
- the pressure-sensitive adhesive is typically in the form of a pressure-sensitive adhesive sheet and is widely used for the purpose of bonding, fixing, protecting, and the like of members in mobile phones and other portable devices.
- Patent Literatures 1 to 5 are given as technical literature on pressure-sensitive adhesive tapes used in portable electronic devices.
- Patent Document 5 is a technical document relating to a pressure-sensitive adhesive sheet with a foam base material.
- the fixing area of a member in a portable electronic device using an adhesive sheet has a small bonding area due to restrictions on size, weight, and the like.
- the pressure-sensitive adhesive sheet used in this application needs to have an adhesive force capable of realizing good fixation even in a small area, and the required performance thereof has become a higher level due to the demand for weight reduction and miniaturization.
- portable electronic devices with a touch panel display, such as smartphones are becoming smaller and thinner, while the screen size is increasing from the viewpoint of display visibility and operability. For this reason, the adhesive used has been required to have an adhesive fixing performance under more severe conditions.
- fixing members in the portable electronic device there is a use in which an elastic member such as a circuit board of an organic EL display is bent, accommodated in a limited internal space in the portable electronic device, and fixed with an adhesive sheet.
- the pressure-sensitive adhesive used for fixing the member has a deformation resistance capable of continuously resisting the elastic rebound of the member under the conditions inside the portable electronic device (specifically, in the thickness direction (Z-axis direction) of the pressure-sensitive adhesive sheet). (Durability against peeling deformation load).
- the temperature and humidity in the portable electronic device may be in a high temperature state exceeding 50 ° C. due to the influence of the external environment as well as the heat in the electronic device, and may be high. .
- a pressure-sensitive adhesive used for this purpose may be required to exhibit stable deformation resistance in the Z-axis direction.
- the pressure-sensitive adhesive used in this application is designed to have a relatively high degree of crosslinking from the viewpoint of ensuring high cohesion leading to deformation resistance.
- the present invention has been made in view of the above circumstances, and an object of the present invention is to provide a pressure-sensitive adhesive sheet that exhibits good deformation resistance even in a severe environment and has excellent impact resistance. .
- an adhesive sheet including a foam base material and an adhesive layer provided on at least one surface of the foam base material.
- the pressure-sensitive adhesive layer contains an acrylic polymer as a base polymer. Further, the pressure-sensitive adhesive layer has a storage elastic modulus G ′ (65 ° C.) at 65 ° C. of more than 30,000 Pa. According to the above configuration, it exhibits good deformation resistance even in a severe environment such as a high temperature condition, and also has excellent impact resistance.
- the monomer component constituting the acrylic polymer contains more than 50% by weight of an alkyl (meth) acrylate having an alkyl group having 1 to 6 carbon atoms at an ester terminal. Including. By using C 1-6 alkyl (meth) acrylate as a main constituent monomer component, it is possible to preferably design an acrylic polymer that can realize deformation resistance to a continuous load in the Z-axis direction.
- the monomer component constituting the acrylic polymer contains a carboxy group-containing monomer.
- the cohesive force of the pressure-sensitive adhesive layer is improved.
- the fact that the monomer component contains a carboxy group-containing monomer can also advantageously contribute to improving the adhesion between the pressure-sensitive adhesive layer and the adherend.
- the content of the carboxy group-containing monomer in the monomer component is suitably about 1% by weight to 10% by weight from the viewpoint of compatibility with other components.
- the pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer contains an isocyanate-based crosslinking agent.
- an isocyanate-based cross-linking agent By using an isocyanate-based cross-linking agent, there is a tendency that while obtaining the cohesive force of the pressure-sensitive adhesive layer, impact resistance superior to other cross-linked systems is obtained.
- the pressure-sensitive adhesive layer according to a preferred embodiment contains at least one selected from tackifier resins and (meth) acrylic oligomers as a tackifier in addition to the base polymer. According to such an adhesive, it is easy to realize good resistance to deformation in the Z-axis direction even in a severe environment such as a high temperature condition.
- the pressure-sensitive adhesive layer according to one embodiment includes a tackifier resin as a tackifier, and substantially does not include a (meth) acrylic oligomer.
- the pressure-sensitive adhesive layer according to another embodiment does not substantially contain a tackifying resin and contains a (meth) acrylic oligomer as a tackifying component.
- the pressure-sensitive adhesive layer according to another embodiment includes a tackifying resin and a (meth) acrylic oligomer as a tackifying component.
- the pressure-sensitive adhesive layer contains a tackifier resin having a hydroxyl value of 70 mgKOH / g or more.
- a tackifier resin having a hydroxyl value of 70 mgKOH / g or more By including the tackifying resin, excellent deformation resistance is easily obtained.
- the pressure-sensitive adhesive using an isocyanate-based cross-linking agent by using a tackifying resin having a high hydroxyl value as described above, in addition to improving the adhesive strength by using the tackifying resin, the high hydroxyl value tackifying resin and the isocyanate
- the pressure-sensitive adhesive layer having high cohesive force can be realized by interaction with the system crosslinking agent.
- the tackifying resin comprises a phenolic tackifying resin.
- Phenolic tackifier resins have excellent compatibility with acrylic polymers.
- the effect of improving the adhesion to the adherend is preferably realized.
- the content of the tackifier resin in the pressure-sensitive adhesive layer is 10 parts by weight or more and 60 parts by weight or less based on 100 parts by weight of the base polymer of the pressure-sensitive adhesive layer. .
- the amount of the tackifier resin is 10 parts by weight or more based on 100 parts by weight of the base polymer, good adhesive strength can be easily obtained.
- the amount of the tackifier resin is 60 parts by weight or less, the resin is well compatible with the base polymer, and good adhesive properties are easily obtained.
- the pressure-sensitive adhesive sheet according to a preferred embodiment has a total thickness of 100 ⁇ m or more. According to the pressure-sensitive adhesive sheet having the above total thickness, the impact resistance tends to be improved.
- the foam base is a polyolefin-based foam base. According to the pressure-sensitive adhesive sheet provided with the polyolefin-based foam base material, the effects of the technology disclosed herein are preferably realized.
- the pressure-sensitive adhesive sheet disclosed herein exhibits good deformation resistance even in a severe environment and has excellent impact resistance, and thus is preferably used for joining parts of portable electronic devices. Since the pressure-sensitive adhesive sheet can exhibit good deformation resistance to a continuous load in the Z-axis direction, it is preferably used, for example, for fixing an elastic adherend such as a circuit board of an organic EL display. According to the pressure-sensitive adhesive sheet, for example, even in a high-temperature environment, the elastic adherend can be fixed in a bent state, and the fixed state can be maintained continuously. Further, for example, by using the pressure-sensitive adhesive sheet disclosed herein for the purpose of fixing a circuit board of an organic EL display arranged in a portable electronic device, it is possible to improve the member accommodation efficiency of the portable electronic device. It is.
- the term "pressure-sensitive adhesive” as used herein refers to a material that exhibits a state of a soft solid (viscoelastic body) in a temperature range around room temperature and has a property of easily adhering to an adherend by pressure.
- the pressure-sensitive adhesive generally has a complex tensile modulus E * (1 Hz) as defined in "C. A. Dahlquist," Adhesion: Fundamental and Practice “, McLaren & Sons, (1966) P. 143. It may be a material having properties satisfying ⁇ 10 7 dyne / cm 2 (typically, a material having the above properties at 25 ° C.).
- the pressure-sensitive adhesive sheet (which may be in a long form such as a tape shape) disclosed herein includes a foam base material and a pressure-sensitive adhesive layer provided on at least one surface of the foam base material. Prepare.
- a pressure-sensitive adhesive sheet may be in the form of a single-sided pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer only on one surface of a foam base material and having only one surface serving as a pressure-sensitive adhesive surface (pressure-sensitive adhesive surface).
- Such a single-sided pressure-sensitive adhesive sheet for example, by fixing the surface having no pressure-sensitive adhesive layer to the adherend by a method other than adhesion (for example, a method using an adhesive, a method of heat fusion), It can be used for joining and fixing parts.
- the pressure-sensitive adhesive sheet disclosed herein is typically preferably implemented in the form of a double-sided pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer on both sides of a foam base material (double-sided pressure-sensitive adhesive sheet with a foam base material).
- Such a double-sided pressure-sensitive adhesive sheet is advantageous, for example, from the viewpoint of simplicity of a joining operation of parts and stability of joining quality.
- the concept of the pressure-sensitive adhesive sheet referred to here may include what is called a pressure-sensitive adhesive tape, a pressure-sensitive adhesive label, a pressure-sensitive adhesive film, or the like.
- the pressure-sensitive adhesive sheet disclosed herein may be in the form of a roll or a sheet. Alternatively, the pressure-sensitive adhesive sheet may be a form processed into various shapes.
- the pressure-sensitive adhesive sheet disclosed herein may have, for example, a cross-sectional structure schematically shown in FIG.
- the pressure-sensitive adhesive sheet 1 includes a foam base material 10, and a first pressure-sensitive adhesive layer 21 and a second pressure-sensitive adhesive layer 22 supported on the first surface 10A and the second surface 10B of the foam base material 10, respectively.
- Each of the first surface 10A and the second surface 10B is a non-peelable surface (non-peelable surface).
- the pressure-sensitive adhesive sheet 1 is used by attaching a surface (first pressure-sensitive surface) 21A of the first pressure-sensitive adhesive layer 21 and a surface (second pressure-sensitive surface) 22A of the second pressure-sensitive adhesive layer 22 to an adherend.
- the pressure-sensitive adhesive sheet 1 was protected by the release liners 31, 32 in which the first pressure-sensitive adhesive surface 21A and the second pressure-sensitive adhesive surface 22A had at least the pressure-sensitive adhesive surface side as a surface having release properties (release surface). It has a configuration.
- the release liner 32 and using a release liner 31 having both sides as release surfaces winding the adhesive sheet 1 and bringing the second adhesive surface 22A into contact with the back surface of the release liner 31
- the second adhesive surface 22 ⁇ / b> A may also be configured to be protected by the release liner 31.
- ⁇ Adhesive layer> (65 ° C storage modulus)
- the pressure-sensitive adhesive layer disclosed herein (in the case where the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer are provided, both of them; the same applies hereinafter unless otherwise specified) has a storage elastic modulus G ′ (65 ° C.) at 65 ° C. ) Is greater than 30,000 Pa.
- G ′ 65 ° C.
- the G ′ (65 ° C.) is preferably higher than 40,000 Pa, more preferably higher than 50,000 Pa, and further preferably 55000 Pa or more.
- G ′ 65 ° C.
- the upper limit of G ′ (65 ° C.) is not limited to a specific range, but is suitably set to 1.0 MPa or less, from the viewpoint of achieving both initial adhesion (for example, low-temperature adhesion) and deformation resistance. Therefore, it is preferably about 500,000 Pa or less, about 200,000 Pa or less, about 100,000 Pa or less, or about 80,000 Pa or less.
- the storage elastic modulus G ′ (65 ° C.) of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer may be the same or different.
- the storage elastic modulus G ′ (65 ° C.) is determined by the composition of the pressure-sensitive adhesive (for example, the monomer composition and molecular weight of the base polymer, the softening point of the tackifying resin, the type of the crosslinking agent, and the content of these components) and the production method (polymerization conditions Etc.).
- the storage elastic modulus at 65 ° C. can be measured by a method described in Examples described later.
- the pressure-sensitive adhesive layer disclosed herein suitably has a loss elastic modulus G ′′ (65 ° C.) at 65 ° C. of about 500,000 Pa or less.
- G ′′ (65 ° C.) is preferably about 100,000 Pa or less, may be about 50,000 Pa or less, or may be about 30,000 Pa or less.
- the G ′′ (65 ° C.) is suitably about 1000 Pa or more, and is preferably about 5000 Pa or more and about 10,000 Pa from the viewpoints of wettability to the surface of the adherend, and thus initial adhesion.
- Those having a pressure-sensitive adhesive layer having a predetermined G ′′ (65 ° C.) or more tend to have excellent impact resistance.
- the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer may have the same or different loss modulus G ′′ (65 ° C.).
- the above-mentioned loss modulus G ′′ (65 ° C.) is determined by the composition of the pressure-sensitive adhesive (for example, the monomer composition and molecular weight of the base polymer, the softening point of the tackifying resin, the type of the crosslinking agent, and the content ratio of these components) and the production method (the polymer Polymerization conditions).
- the 65 ° C. loss elastic modulus can be measured by a method described in Examples described later.
- the storage elastic modulus at 25 ° C. of the pressure-sensitive adhesive layer disclosed herein is not particularly limited, and may be, for example, about 1 MPa or less.
- the storage elastic modulus at 25 ° C. of the pressure-sensitive adhesive layer may be about 0.5 MPa or less, preferably about 0.3 MPa or less (for example, about 0.25 MPa or less).
- the flexibility of the pressure-sensitive adhesive layer is increased in a normal temperature range, so that the pressure-sensitive adhesive surface is easily brought into close contact with the surface of the adherend. Further, according to the pressure-sensitive adhesive whose storage modulus is limited to a predetermined value or less, good impact resistance is easily obtained.
- the storage elastic modulus at 25 ° C. may be about 0.01 MPa or more.
- the pressure-sensitive adhesive exhibiting a storage elastic modulus of 25 ° C. which is equal to or higher than a predetermined value it has an appropriate cohesive property in a normal temperature range, so that the adhesive strength is easily increased.
- the storage elastic modulus at 25 ° C. is suitably about 0.02 MPa or more, preferably 0.05 MPa or more, more preferably about 0.1 MPa or more, and still more preferably about 0.14 MPa.
- the storage elastic modulus at 25 ° C. of the pressure-sensitive adhesive layer can be adjusted by the composition of the pressure-sensitive adhesive layer, the production method, and the like.
- the 25 ° C. storage elastic modulus can be measured by the method described in Examples described later.
- the 25 ° C. loss elastic modulus of the pressure-sensitive adhesive layer disclosed herein is not particularly limited, and may be, for example, about 0.01 MPa or more.
- the 25 ° C. loss elastic modulus of the pressure-sensitive adhesive layer is suitably about 0.02 MPa or more, preferably 0.05 MPa or more, more preferably about 0.1 MPa or more, still more preferably about 0.15 MPa or more, and particularly preferably. Is about 0.17 MPa or more (for example, about 0.2 MPa or more).
- the adhesion to the adherend is improved based on the viscosity term (loss elastic modulus).
- the 25 ° C. loss elastic modulus of the pressure-sensitive adhesive layer increases, the impact resistance tends to improve.
- the 25 ° C. loss elastic modulus of the pressure-sensitive adhesive layer may be, for example, about 1 MPa or less. From the viewpoint of cohesiveness and the like, the 25 ° C. loss elastic modulus of the pressure-sensitive adhesive layer may be about 0.5 MPa or less, preferably about 0.3 MPa or less (for example, about 0.25 MPa or less).
- the 25 ° C. loss elastic modulus of the pressure-sensitive adhesive layer can be adjusted by the composition of the pressure-sensitive adhesive layer, the production method, and the like. The 25 ° C. loss elastic modulus can be measured by a method described in Examples described later.
- the Tg of the pressure-sensitive adhesive layer constituting the pressure-sensitive adhesive sheet disclosed herein is controlled to be approximately 25 ° C. or lower, which means that the adhesiveness to the adherend and the impact resistance Appropriate from a viewpoint.
- the Tg of the pressure-sensitive adhesive layer is preferably about 20 ° C. or less (typically about 15 ° C. or less, for example, about 10 ° C. or less).
- the Tg of the pressure-sensitive adhesive layer is suitably from about ⁇ 25 ° C. or more, preferably from about ⁇ 15 ° C. or more, more preferably from about ⁇ 10 ° C.
- Tg desired adhesive properties (for example, adhesive strength and impact resistance) can be preferably realized.
- the type of tackifying resin for example, a high hydroxyl value resin
- the action based on the viscoelastic properties of the pressure-sensitive adhesive and the chemical properties of the tackifying resin is preferable. Can be demonstrated.
- the Tg of the pressure-sensitive adhesive layer in this specification refers to a glass transition temperature obtained from a tan ⁇ peak temperature in dynamic viscoelasticity measurement.
- the Tg of the pressure-sensitive adhesive layer can be adjusted by the pressure-sensitive adhesive composition (for example, the Tg of the base polymer, the softening point of the tackifying resin, the type of the crosslinking agent, and the content ratio of these components) and the production method (polymerization conditions of the polymer and the like). .
- the Tg of the pressure-sensitive adhesive layer can be measured by a method described in Examples described later.
- the value of the tan ⁇ peak (peak intensity) of the pressure-sensitive adhesive layer is typically 1.0 or more, preferably about 1.5 or more, more preferably about 1.8 or more, and still more preferably about 2.0 or more. That is all.
- pressure-sensitive adhesives having a tan ⁇ peak in a relatively low temperature range typically in the range of ⁇ 25 ° C. to 25 ° C.
- those having a peak intensity of a predetermined value or more can be excellent in impact resistance.
- the peak intensity of the tan ⁇ is suitably about 3.0 or less, preferably about 2.5 or less, and may be less than about 2.2 (for example, less than 2.0).
- the tan ⁇ peak intensity of the pressure-sensitive adhesive layer is adjusted by the pressure-sensitive adhesive composition (for example, Tg of base polymer, softening point of tackifying resin, kind of cross-linking agent, content of these components) and production method (polymerization conditions of polymer and the like). be able to.
- the peak intensity of tan ⁇ of the pressure-sensitive adhesive layer can be measured by a method described in Examples described later.
- the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer disclosed herein is an acrylic pressure-sensitive adhesive containing an acrylic polymer as a base polymer.
- the base polymer refers to a main component of a rubbery polymer (a polymer exhibiting rubber elasticity in a temperature range around room temperature) contained in the pressure-sensitive adhesive layer.
- main component refers to a component contained in excess of 50% by weight unless otherwise specified.
- the term "acrylic pressure-sensitive adhesive” refers to a pressure-sensitive adhesive containing an acrylic polymer as a base polymer (a main component of the polymer component, that is, a component occupying 50% by weight or more).
- the “acrylic polymer” refers to a polymer containing, as a monomer unit constituting the polymer, a monomer unit derived from a monomer having at least one (meth) acryloyl group in one molecule.
- a monomer having at least one (meth) acryloyl group in one molecule is also referred to as an “acrylic monomer”. Therefore, the acrylic polymer in this specification is defined as a polymer containing a monomer unit derived from an acrylic monomer.
- (meth) acryloyl” means acryloyl and methacryloyl comprehensively.
- (meth) acrylate” means acrylate and methacrylate
- “(meth) acryl” means acryl and methacryl, respectively.
- acrylic polymer for example, a polymer of a monomer raw material which contains alkyl (meth) acrylate as a main monomer and may further contain a sub-monomer having copolymerizability with the main monomer is preferable.
- the main monomer means a component occupying more than 50% by weight of the monomer composition in the monomer raw material.
- alkyl (meth) acrylate for example, a compound represented by the following formula (1) can be suitably used.
- R 1 in the above formula (1) is a hydrogen atom or a methyl group.
- R 2 is a chain alkyl group having 1 to 20 carbon atoms. Hereinafter, such a range of the number of carbon atoms may be referred to as “C 1-20 ”.
- alkyl (meth) acrylate in which R 2 is a C 1-14 (for example, C 2-10 or C 4-8 ) chain alkyl group may be used as a main monomer. Appropriate.
- an alkyl acrylate in which R 1 is a hydrogen atom and R 2 is a C 4-8 chain alkyl group (hereinafter, also simply referred to as C 4-8 alkyl acrylate) is used as a main monomer. Is preferred.
- alkyl (meth) acrylate in which R 2 is a C 1-20 chain alkyl group examples include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, and n-butyl.
- alkyl (meth) acrylates can be used alone or in combination of two or more.
- Preferred alkyl (meth) acrylates include n-butyl acrylate (BA) and 2-ethylhexyl acrylate (2EHA).
- the ratio of the alkyl (meth) acrylate to all the monomer components used for the synthesis of the acrylic polymer is preferably 70% by weight or more, more preferably 85% by weight or more, and further preferably 90% by weight or more.
- the upper limit of the ratio of the alkyl (meth) acrylate is not particularly limited, it is suitably 99.5% by weight or less (for example, 99% by weight or less), and suitably exerts the action of the auxiliary monomer such as a carboxy group-containing monomer. In light of this, the content is preferably about 98% by weight or less (eg, 97% by weight or less).
- the acrylic polymer according to a preferred embodiment is a polymer of a monomer component that contains C 1-6 alkyl (meth) acrylate as a main monomer and may further contain a sub-monomer having copolymerizability with the main monomer.
- C 1-6 alkyl (meth) acrylate one type can be used alone, or two or more types can be used in combination.
- C 1-6 alkyl (meth) acrylate it is easy to obtain a pressure-sensitive adhesive having good deformation resistance and impact resistance.
- the acrylic polymer preferably has a main monomer is C 1-5 alkyl (meth) acrylate, and more preferably C 1-4 alkyl (meth) acrylate.
- the main monomer is C 2-6 alkyl (meth) acrylate, more preferably C 4-6 alkyl (meth) acrylate, from the viewpoint of adhesion to an adherend and the like.
- the main monomer is C 1-6 alkyl acrylate, and more preferably C 1-4 alkyl acrylate (for example, C 2-4 alkyl acrylate) from the viewpoint of improving the adhesion. It is.
- the C 1-6 alkyl (meth) acrylate has a glass transition temperature (Tg) of a homopolymer of about 20 ° C. or less (typically, from the viewpoint of improving impact resistance and adhesion to an adherend and a substrate).
- Tg glass transition temperature
- C 1-6 alkyl (meth) acrylate having a temperature of about 10 ° C. or less, preferably about 0 ° C. or less, more preferably about ⁇ 10 ° C. or less, and still more preferably about ⁇ 15 ° C. or less can be preferably employed.
- the technology disclosed herein can be preferably implemented, for example, in an embodiment in which the main monomer of the acrylic polymer is BA.
- the C 1-6 alkyl (meth) acrylate (typically among the monomer components constituting the acrylic polymer C 1-
- the proportion occupied by 6 alkyl acrylates is preferably about 60% by weight or more, more preferably about 75% by weight or more, and more preferably about 85% by weight or more.
- the technique disclosed herein is, for example, about 70% by weight or more (more preferably about 80% by weight or more, more preferably about 85% by weight or more, about 90% by weight or more or about 95% by weight of the monomer component). Above may be BA).
- Acrylic polymers in the technology disclosed herein may be copolymerized with other monomers (other monomers) as needed, as long as the effects of the present invention are not significantly impaired.
- the above other monomers can be used for the purpose of, for example, adjusting the Tg of the acrylic polymer, improving the cohesion, adjusting the initial adhesiveness, and the like.
- sulfonic acid group-containing monomers, phosphoric acid group-containing monomers, cyano group-containing monomers, vinyl esters, aromatic vinyl compounds and the like can be mentioned as monomers capable of improving the cohesive strength and heat resistance of the pressure-sensitive adhesive.
- Preferable examples of these include vinyl esters.
- Specific examples of vinyl esters include vinyl acetate (VAc), vinyl propionate, vinyl laurate and the like. Among them, VAc is preferable.
- a functional group that can be a cross-linking base point is introduced into the acrylic polymer, or as other monomers that can contribute to improvement in peel strength, a hydroxyl group-containing monomer, a carboxy group-containing monomer, an acid anhydride group-containing monomer, an amide group-containing monomer, Amino group-containing monomers, imide group-containing monomers, epoxy group-containing monomers, (meth) acryloyl morpholine, vinyl ethers, and the like.
- a preferred example of the acrylic polymer in the technology disclosed herein is an acrylic polymer in which a carboxy group-containing monomer is copolymerized as the other monomer.
- a pressure-sensitive adhesive layer having high cohesive strength tends to be easily obtained.
- the fact that the monomer component contains a carboxy group-containing monomer can also advantageously contribute to improving the adhesion between the pressure-sensitive adhesive layer and the adherend or substrate. For example, it can exhibit improved adhesion to adherends made of polyester resin such as polyethylene terephthalate (PET).
- PET polyethylene terephthalate
- carboxy group-containing monomer examples include acrylic acid (AA), methacrylic acid (MAA), carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, and the like. Is done.
- the carboxy group-containing monomers can be used alone or in combination of two or more. Among them, preferred carboxy group-containing monomers include AA and MAA. AA is particularly preferred. AA is a compound having a carboxy group, a role as a cross-linking point, and a complex action such as Tg (106 ° C.). It is considered to be an optimal monomer material for realizing deformation resistance to
- acrylic polymer in the technology disclosed herein is an acrylic polymer obtained by copolymerizing a hydroxyl group-containing monomer as the other monomer.
- the hydroxyl group-containing monomer may be copolymerized with the carboxy group-containing monomer.
- examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 4-hydroxybutyl (meth).
- hydroxyalkyl (meth) acrylates such as acrylates; polypropylene glycol mono (meth) acrylate; N-hydroxyethyl (meth) acrylamide and the like.
- a preferred hydroxyl group-containing monomer has a hydroxyl group at the terminal of a linear alkyl group having about 2 to 4 carbon atoms, such as 2-hydroxyethyl acrylate (HEA) and 4-hydroxybutyl acrylate (4-HBA). Hydroxyalkyl (meth) acrylate is exemplified.
- the above “other monomers” can be used alone or in combination of two or more.
- the total content of other monomers can be, for example, less than about 50% by weight (typically about 0.001 to 40% by weight) of all monomer components, and about 25% by weight or less (typically It is appropriate to set it to about 0.01 to 25% by weight, for example, about 0.1 to 20% by weight.
- a carboxy group-containing monomer When a carboxy group-containing monomer is used as the other monomer, its content is suitably at least about 0.1% by weight of all monomer components, preferably at least about 0.2% by weight, more preferably at least about 0.2% by weight. It is at least 0.5% by weight, more preferably at least about 1% by weight, particularly preferably at least about 2% by weight (for example, at least about 3% by weight, further preferably at least 4% by weight).
- the content of the carboxy group-containing monomer increases, the cohesive force of the pressure-sensitive adhesive layer generally tends to increase, and the deformation resistance in the Z-axis direction under high-temperature conditions tends to improve.
- the amount of the carboxy group-containing monomer is suitably not more than about 20% by weight of all the monomer components, preferably not more than about 15% by weight, more preferably not more than about 12% by weight, and still more preferably not more than about 10% by weight. %, Particularly preferably about 8% by weight or less (for example, about 7% by weight or less).
- a hydroxyl group-containing monomer When a hydroxyl group-containing monomer is used as the above-mentioned other monomer, its content is suitably at least about 0.001% by weight of all monomer components, and preferably at least about 0.01% by weight (for example, about 0% by weight). 0.02% by weight or more). Further, the content of the hydroxyl group-containing monomer is suitably not more than about 10% by weight, preferably not more than about 5% by weight, and more preferably not more than about 2% by weight in all the monomer components.
- the copolymer composition of the acrylic polymer is designed so that the Tg of the polymer is about -15 ° C or less (typically, about -70 ° C or more and -15 ° C or less).
- the Tg of the acrylic polymer refers to the Tg determined by the Fox equation based on the composition of the monomer component used in the synthesis of the polymer.
- the Fox equation is a relational expression between the Tg of the copolymer and the glass transition temperature Tgi of a homopolymer obtained by homopolymerizing each of the monomers constituting the copolymer, as shown below.
- Tg is the glass transition temperature (unit: K) of the copolymer
- Wi is the weight fraction of the monomer i in the copolymer (copolymerization ratio on a weight basis)
- Tgi is the weight of the monomer i. Represents the glass transition temperature (unit: K) of the homopolymer.
- glass transition temperature of the homopolymer used for calculating Tg a value described in a publicly known document is used.
- the monomers listed below the following values are used as the glass transition temperatures of homopolymers of the monomers.
- the mixture is cooled to room temperature to obtain a homopolymer solution having a solid content of 33% by weight.
- the homopolymer solution is cast on a release liner and dried to prepare a test sample (sheet-like homopolymer) having a thickness of about 2 mm.
- This test sample was punched into a disk shape having a diameter of 7.9 mm, sandwiched between parallel plates, and subjected to a shear strain at a frequency of 1 Hz using a viscoelasticity tester (TA Instruments Japan, model name "ARES"). And the viscoelasticity is measured in a shear mode at a heating rate of -70 ° C. to 150 ° C. and 5 ° C./min, and the peak top temperature of tan ⁇ (loss tangent) is defined as Tg of the homopolymer.
- the Tg of the acrylic polymer is advantageously about ⁇ 25 ° C. or less, and preferably about ⁇ 35 ° C., from the viewpoint of adhesion to an adherend and a substrate and impact resistance. ° C or lower, more preferably about -40 ° C or lower. Further, from the viewpoint of the cohesive force of the pressure-sensitive adhesive layer, the Tg of the acrylic polymer is advantageously about -65 ° C or more, preferably about -60 ° C or more, more preferably about -55 ° C or more. .
- the technology disclosed herein can be preferably practiced in an embodiment in which the Tg of the acrylic polymer is about -65 ° C to -35 ° C (for example, about -55 ° C to -40 ° C).
- the Tg of the acrylic polymer can be adjusted by appropriately changing the monomer composition (that is, the type and the ratio of the amount of the monomer used in the synthesis of the polymer).
- the method for obtaining the acrylic polymer is not particularly limited, and various polymerization methods known as synthetic methods for the acrylic polymer, such as a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, a suspension polymerization method, and a photopolymerization method. Can be appropriately adopted.
- a solution polymerization method can be preferably employed.
- a monomer supply method at the time of performing the solution polymerization a batch charging method, a continuous supply (dropping) method, a divided supply (dropping) method, or the like that supplies all the monomer raw materials at once can be appropriately adopted.
- the polymerization temperature can be appropriately selected depending on the type of the monomer and the solvent to be used, the type of the polymerization initiator, and the like.
- the polymerization temperature is about 20 ° C. to 170 ° C. (typically about 40 ° C. to 140 ° C.). Can be.
- the polymerization temperature can be about 75 ° C. or lower (more preferably about 65 ° C. or lower, for example, about 45 ° C. to 65 ° C.).
- the solvent (polymerization solvent) used for the solution polymerization can be appropriately selected from conventionally known organic solvents.
- aromatic compounds such as toluene (typically aromatic hydrocarbons); acetates such as ethyl acetate; aliphatic or alicyclic hydrocarbons such as hexane and cyclohexane; 1,2-dichloroethane and the like Halogenated alkanes; lower alcohols such as isopropyl alcohol (for example, monohydric alcohols having 1 to 4 carbon atoms); ethers such as tert-butyl methyl ether; ketones such as methyl ethyl ketone; Any one type of solvent or a mixture of two or more types can be used.
- the initiator used for the polymerization can be appropriately selected from conventionally known polymerization initiators according to the type of the polymerization method.
- one or more azo polymerization initiators such as 2,2'-azobisisobutyronitrile (AIBN) can be preferably used.
- Other examples of the polymerization initiator include persulfates such as potassium persulfate; peroxide initiators such as benzoyl peroxide (BPO) and hydrogen peroxide; substituted ethane initiators such as phenyl-substituted ethane; Group carbonyl compounds; and the like.
- Still another example of the polymerization initiator includes a redox initiator formed by a combination of a peroxide and a reducing agent.
- Such polymerization initiators can be used alone or in combination of two or more.
- the amount of the polymerization initiator used may be a usual amount, for example, about 0.005 to 1 part by weight (typically about 0.01 to 1 part by weight) based on 100 parts by weight of all monomer components. Degree).
- a polymerization reaction solution in which an acrylic polymer is dissolved in an organic solvent is obtained.
- the pressure-sensitive adhesive layer in the technology disclosed herein may be formed from a pressure-sensitive adhesive composition containing the above-mentioned polymerization reaction solution or an acrylic polymer solution obtained by subjecting the reaction solution to an appropriate post-treatment.
- the acrylic polymer solution a solution prepared by adjusting the polymerization reaction solution to an appropriate viscosity (concentration) as necessary can be used.
- an acrylic polymer solution prepared by synthesizing an acrylic polymer by a polymerization method other than solution polymerization for example, emulsion polymerization, photopolymerization, bulk polymerization, etc.
- a polymerization method other than solution polymerization for example, emulsion polymerization, photopolymerization, bulk polymerization, etc.
- dissolving the acrylic polymer in an organic solvent may be used. Good.
- the weight average molecular weight (Mw) of the base polymer (preferably an acrylic polymer) in the technology disclosed herein is not particularly limited, and may be, for example, in a range of about 10 ⁇ 10 4 to 500 ⁇ 10 4 .
- the upper limit of the above Mw is preferably about 200 ⁇ 10 4 or less, more preferably about 150 ⁇ 10 4 or less, further more preferably about 140 ⁇ 10 4 or less, from the viewpoints of adhesive performance, adhesive preparation properties, and the like. It may be 130 ⁇ 10 4 or less.
- the Mw of the base polymer is preferably about 30 ⁇ 10 4 or more, more preferably about 45 ⁇ 10 4 or more, and still more preferably about 50 ⁇ 10 4 or more (for example, about 60 ⁇ 10 4 or more). ⁇ 10 4 or more). In a preferred embodiment, the Mw is about 110 ⁇ 10 4 or less (for example, about 90 ⁇ 10 4 or less, further about 80 ⁇ 10 4 or less).
- a target high-temperature deformation resistance, a high-temperature holding force, and impact resistance can be realized with a configuration using an acrylic polymer having Mw of 70 ⁇ 10 4 or less.
- the Mw is 70 ⁇ 10 4 or more, and more preferably, from the viewpoint of deformation resistance to a continuous load in the Z-axis direction based on the improvement in cohesiveness of the high molecular weight body. It is about 75 ⁇ 10 4 or more, more preferably about 90 ⁇ 10 4 or more, particularly preferably about 95 ⁇ 10 4 or more. In still another aspect, the Mw is approximately 100 ⁇ 10 4 or more (for example, approximately 110 ⁇ 10 4 or more), and may be 120 ⁇ 10 4 or more (for example, 130 ⁇ 10 4 or more).
- the degree of dispersion (Mw / Mn) of the acrylic polymer disclosed herein is not particularly limited.
- the degree of dispersion (Mw / Mn) refers to the degree of dispersion (Mw / Mn) represented by the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn).
- the acrylic polymer has a degree of dispersion (Mw / Mn) of less than 15.
- Mw / Mn of the acrylic polymer is less than 15, it means that the polymer contains a relatively large amount of a relatively uniform high-molecular-weight polymer. It tends to show deformability.
- the Mw / Mn is preferably less than 12, more preferably less than 10, and even more preferably less than 8 (for example, 7.5 or less). In some embodiments, the Mw / Mn is less than 6 (eg, less than 5.5). Further, Mw / Mn is theoretically 1 or more, for example, 2 or more, 3 or more, or 4 or more. In another preferred embodiment, the degree of dispersion (Mw / Mn) of the acrylic polymer is from 8 to 40. When the Mw / Mn of the acrylic polymer is 8 or more and 40 or less, it can mean that the molecular weight distribution is wide and the low molecular weight and the high molecular weight are contained in a considerable amount.
- the low molecular weight body contributes to the development of initial adhesiveness due to good wettability to the adherend, and the high molecular weight body exhibits resistance to sustained deformation load (deformation resistance) due to its cohesiveness.
- the initial adhesiveness is preferably exhibited.
- the Mw / Mn is 40 or less, the molecular weight distribution is preferably limited to an appropriate range, and stable characteristics (initial adhesion and deformation resistance) can be obtained.
- the above Mw / Mn is preferably 10 or more, more preferably 12 or more, and further preferably 15 or more. Further, the Mw / Mn is preferably 35 or less, more preferably 30 or less, further preferably 25 or less, and may be 20 or less (for example, less than 20).
- Mw, Mn and Mw / Mn can be adjusted by polymerization conditions (time, temperature, etc.), use of a chain transfer agent, selection of a polymerization solvent based on a chain transfer constant, and the like. Further, Mw and Mn are determined from values in terms of standard polystyrene obtained by GPC (gel permeation chromatography).
- GPC gel permeation chromatography
- a model name “HLC-8320GPC” columnumn: TSKgelGMH-H (S), manufactured by Tosoh Corporation
- the pressure-sensitive adhesive layer disclosed herein preferably contains a tackifier resin in addition to the base polymer.
- a tackifier resin rosin-based resin, terpene resin, modified terpene resin, phenolic resin, styrene-based resin, hydrocarbon-based tackifying resin, epoxy-based tackifying resin, polyamide-based tackifying resin, elastomer-based tackifying resin.
- tackifier resins such as ketone resins can be used. Of these, phenolic tackifier resins are preferred.
- phenolic tackifying resins include terpene phenolic resins, hydrogenated terpene phenolic resins, alkyl phenolic resins, and rosin phenolic resins.
- a terpene phenol resin refers to a polymer containing a terpene residue and a phenol residue, and includes a copolymer of a terpene and a phenol compound (terpene-phenol copolymer resin) and a homopolymer or a copolymer of a terpene.
- phenol-modified (phenol-modified terpene resin) phenol-modified terpene resin
- terpenes constituting such a terpene phenol resin include monoterpenes such as ⁇ -pinene, ⁇ -pinene, limonene (including d-form, l-form and d / l-form (dipentene)).
- the hydrogenated terpene phenol resin refers to a hydrogenated terpene phenol resin having a structure obtained by hydrogenating such a terpene phenol resin.
- hydrogenated terpene phenolic resin is sometimes referred to as hydrogenated terpene phenolic resin.
- the alkylphenol resin is a resin (oil-based phenol resin) obtained from alkylphenol and formaldehyde.
- the alkylphenol resin examples include a novolak type and a resol type.
- the rosin phenol resin is typically a rosin or a phenol-modified rosin derivative (including rosin esters, unsaturated fatty acid-modified rosins and unsaturated fatty acid-modified rosin esters).
- Examples of the rosin phenol resin include a rosin phenol resin obtained by, for example, a method of adding phenol to a rosin or the above-mentioned various rosin derivatives with an acid catalyst and performing thermal polymerization.
- the concept of the rosin-based resin here includes both rosins and rosin derivative resins.
- the rosin phenol resin described below is treated as belonging to the phenol resin rather than the rosin resin.
- rosins include unmodified rosins (raw rosins) such as gum rosin, wood rosin, and tall oil rosin; and modified rosins (hydrogenated rosins, unmodified rosins) obtained by modifying these unmodified rosins by hydrogenation, disproportionation, polymerization, and the like. Rosin, polymerized rosin, other chemically modified rosins, etc.).
- the rosin derivative resin is typically a rosin derivative as described above.
- the concept of the rosin-based resin referred to here includes derivatives of unmodified rosin and derivatives of modified rosin (including hydrogenated rosin, disproportionated rosin, and polymerized rosin).
- rosin derivative resin for example, rosin esters such as unmodified rosin ester which is an ester of unmodified rosin and alcohol, and modified rosin ester which is an ester of modified rosin and alcohol; Unsaturated fatty acid-modified rosins modified with fatty acids; for example, unsaturated fatty acid-modified rosin esters obtained by modifying rosin esters with unsaturated fatty acids; for example, rosins or the above-mentioned various rosin derivatives (rosin esters, unsaturated fatty acid-modified) Rosins and unsaturated fatty acid-modified rosin esters), the carboxy group of which has been reduced; rosins; metal salts of rosins or the above-mentioned various rosin derivatives; and the like.
- rosin esters such as unmodified rosin ester which is an ester of unmodified rosin and alcohol, and modified rosin ester which is an ester
- rosin esters include methyl ester, unmodified rosin or modified rosin (hydrogenated rosin, disproportionated rosin, polymerized rosin, etc.), triethylene glycol ester, glycerin ester, pentane Erythritol esters and the like.
- terpene resins include polymers of terpenes (typically monoterpenes) such as ⁇ -pinene, ⁇ -pinene, d-limonene, l-limonene, dipentene, and the like. . It may be a homopolymer of one type of terpene or a copolymer of two or more types of terpenes. Examples of the homopolymer of one type of terpene include an ⁇ -pinene polymer, a ⁇ -pinene polymer, a dipentene polymer, and the like. Examples of the modified terpene resin include those obtained by modifying the above terpene resin.
- styrene-modified terpene resins styrene-modified terpene resins, hydrogenated terpene resins and the like are exemplified.
- a terpene phenol resin or a hydrogenated terpene phenol resin described below is treated as belonging to a phenolic resin, not a modified terpene resin.
- hydrocarbon-based tackifying resin examples include aliphatic hydrocarbon resins, aromatic hydrocarbon resins, aliphatic cyclic hydrocarbon resins, aliphatic / aromatic petroleum resins (styrene-olefin copolymers, etc.). ), Various hydrocarbon resins such as aliphatic / alicyclic petroleum resins, hydrogenated hydrocarbon resins, cumarone resins, and cumarone indene resins.
- the tackifier resin contains one or more phenolic tackifier resins (typically, a terpene phenol resin).
- phenolic tackifier resin typically, a terpene phenol resin.
- the adhesiveness of the pressure-sensitive adhesive layer to the adherend can be improved.
- the phenol-based tackifying resin tends to have excellent compatibility in an aspect using an acrylic polymer as the base polymer, and has an advantage that it easily exhibits desired adhesive properties.
- the technology disclosed herein can be preferably implemented, for example, in a mode in which about 25% by weight or more (more preferably about 30% by weight or more) of the total amount of the tackifier resin is a terpene phenol resin.
- About 50% by weight or more of the total amount of the tackifier resin may be a terpene phenolic resin, and about 80% by weight or more (for example, about 90% by weight or more) may be a terpene phenolic resin.
- Substantially all of the tackifying resin eg, about 95-100% by weight, or even about 99-100% by weight
- the content of the phenolic tackifier resin is not particularly limited, and is suitably about 5 parts by weight or more based on 100 parts by weight of the base polymer. It is about 10 parts by weight or more, more preferably about 15 parts by weight or more, and still more preferably about 20 parts by weight or more (for example, about 25 parts by weight or more). Further, the content of the phenolic tackifier resin (for example, terpene phenol resin) is suitably about 80 parts by weight or less, and from the viewpoints of compatibility with the base polymer, and adhesive properties such as adhesive strength and impact resistance. Preferably, it is less than 70 parts by weight, more preferably about 60 parts by weight or less, further preferably about 55 parts by weight or less, particularly preferably about 45 parts by weight or less (for example, about 40 parts by weight or less).
- a tackifier resin having a hydroxyl value of less than 30 mgKOH / g (for example, less than 20 mgKOH / g) can be used.
- a tackifier resin having a hydroxyl value of less than 30 mgKOH / g may be referred to as a “low hydroxyl value resin”.
- the hydroxyl value of the low hydroxyl value resin may be about 15 mgKOH / g or less, or about 10 mgKOH / g or less.
- the lower limit of the hydroxyl value of the low hydroxyl value resin is not particularly limited, and may be substantially 0 mgKOH / g.
- a tackifier resin having a hydroxyl value of 30 mgKOH / g or more may be used as the tackifier resin in the technology disclosed herein.
- a tackifier resin having a hydroxyl value of 30 mg KOH / g or more may be referred to as a “high hydroxyl value resin”.
- the hydroxyl value is suitably at least 40 mgKOH / g, preferably at least 50 mgKOH / g, more preferably at least 60 mgKOH / g.
- the upper limit of the hydroxyl value of the high hydroxyl value resin is not particularly limited.
- the hydroxyl value of the high hydroxyl value resin is appropriately about 200 mgKOH / g or less, preferably about 180 mgKOH / g or less, more preferably about 160 mgKOH / g or less, and still more preferably. Is about 140 mgKOH / g or less.
- the pressure-sensitive adhesive layer contains a tackifier resin having a hydroxyl value of 70 mgKOH / g or more.
- a tackifier resin having a hydroxyl value of 70 mgKOH / g or more By using such a high hydroxyl value resin, excellent deformation resistance can be easily obtained.
- the pressure-sensitive adhesive using an isocyanate-based cross-linking agent by using a tackifying resin having a high hydroxyl value as described above, in addition to improving the adhesive strength by using the tackifying resin, the high hydroxyl value tackifying resin and the isocyanate
- the pressure-sensitive adhesive layer having high cohesive force can be realized by interaction with the system crosslinking agent.
- the hydroxyl value of the high hydroxyl value resin may be about 80 mgKOH / g or more (for example, about 100 mgKOH / g or more).
- the upper limit of the hydroxyl value of the high hydroxyl value resin is not particularly limited. From the viewpoint of compatibility with the base polymer, the hydroxyl value of the high hydroxyl value resin is suitably about 350 mg KOH / g or less, preferably about 300 mg KOH / g or less (for example, about 250 mg KOH / g or less), and more preferably about 250 mg KOH / g or less. It is 200 mgKOH / g or less, and may be about 150 mgKOH / g or less (for example, about 120 mgKOH / g or less).
- a value measured by a potentiometric titration method specified in JIS K0070: 1992 can be adopted.
- the specific measuring method is as shown below.
- [Method for measuring hydroxyl value] 1.
- Reagent (1) As an acetylation reagent, use about 12.5 g (about 11.8 mL) of acetic anhydride, add pyridine to make the total volume 50 mL, and sufficiently stir. Alternatively, about 25 g (about 23.5 mL) of acetic anhydride is taken, pyridine is added thereto to make the total amount 100 mL, and the mixture is sufficiently stirred.
- Hydroxyl value [(BC) ⁇ f ⁇ 28.05] / S + D here
- B Amount (mL) of 0.5 mol / L potassium hydroxide ethanol solution used for blank test
- C amount (mL) of 0.5 mol / L potassium hydroxide ethanol solution used for the sample
- f Factor of 0.5 mol / L potassium hydroxide ethanol solution
- S sample weight (g)
- D acid value
- 28.05 1/2 of molecular weight 56.11 of potassium hydroxide
- the high hydroxyl value resin those having a hydroxyl value equal to or higher than a predetermined value among the various tackifier resins described above can be used.
- the high hydroxyl value resin can be used alone or in combination of two or more.
- a phenolic tackifier resin having a hydroxyl value of 70 mgKOH / g or more can be preferably used as the high hydroxyl value resin.
- a terpene phenol resin having a hydroxyl value of 70 mgKOH / g or more is used as the tackifier resin.
- Terpene phenol resins are advantageous because the hydroxyl value can be arbitrarily controlled by the copolymerization ratio of phenol.
- the proportion of the high hydroxyl value resin (for example, terpene phenol resin) in the entire tackifier resin contained in the pressure-sensitive adhesive layer can be, for example, about 25% by weight or more, and about 30% by weight.
- the above is preferable, and about 50% by weight or more (for example, about 80% by weight or more, typically about 90% by weight or more) is more preferable.
- Substantially all (for example, about 95 to 100% by weight, or even about 99 to 100% by weight) of the tackifier resin may be a high hydroxyl value resin.
- the pressure-sensitive adhesive layer disclosed herein contains a tackifying resin (specifically, a tackifying resin having a hydroxyl value of less than 70 mgKOH / g) that does not correspond to a high hydroxyl value resin within a range that does not impair the effects of the invention. May be included.
- a tackifying resin specifically, a tackifying resin having a hydroxyl value of less than 70 mgKOH / g
- the content of the high hydroxyl value resin is suitably about 5 parts by weight or more (for example, 10 parts by weight or more) based on 100 parts by weight of the base polymer.
- a pressure-sensitive adhesive sheet exhibiting excellent adhesion to an adherend and excellent deformation resistance can be preferably realized.
- the content of the high hydroxyl value resin based on 100 parts by weight of the base polymer is preferably about 15 parts by weight or more, more preferably about 20 parts by weight or more, and still more preferably about 25 parts by weight or more. Particularly preferably, it is about 30 parts by weight or more.
- the upper limit of the content of the high hydroxyl value resin is not particularly limited.
- the content is preferably about 80 parts by weight or less based on 100 parts by weight of the base polymer.
- adhesive properties such as adhesion and impact resistance, it is preferably less than 70 parts by weight, more preferably about 60 parts by weight or less, further preferably about 55 parts by weight or less, and particularly preferably about 50 parts by weight. Below (for example, about 45 parts by weight or less), and may be about 40 parts by weight or less (for example, about 35 parts by weight or less).
- the softening point of the tackifier resin is not particularly limited. From the viewpoint of improving cohesion, in one embodiment, a tackifier resin having a softening point (softening temperature) of about 80 ° C. or more (preferably about 100 ° C. or more) can be preferably used. The softening point is more preferably about 110 ° C. or higher (for example, about 120 ° C. or higher).
- a phenolic tackifier resin having the above softening point (such as a terpene phenol resin) can be preferably used.
- the tackifying resin having the above softening point is used in an amount of more than 50% by weight (more preferably more than 70% by weight, for example, more than 90% by weight) of the entire tackifying resin contained in the pressure-sensitive adhesive layer. It may be preferably implemented in certain aspects.
- a phenolic tackifier resin having the above softening point (such as a terpene phenol resin) can be preferably used.
- the upper limit of the softening point of the tackifier resin is not particularly limited. From the viewpoint of adhesion to an adherend or a substrate, in one embodiment, a tackifier resin having a softening point of about 200 ° C.
- the pressure-sensitive adhesive layer disclosed herein may contain a tackifier resin having a softening point of, for example, about 150 ° C. or lower or about 140 ° C. or lower, and substantially includes a tackifier resin having a softening point of 150 ° C. or lower (eg, 140 ° C. or lower). May not be included.
- the softening point of the tackifier resin can be measured based on the softening point test method (ring and ball method) specified in JIS K2207.
- the content of the tackifier resin is not particularly limited, and is suitably about 5 parts by weight or more (for example, 10 parts by weight or more) based on 100 parts by weight of the base polymer. Thereby, the effect of improving the adhesion to the adherend is suitably exhibited.
- the content of the tackifying resin with respect to 100 parts by weight of the base polymer is preferably about 15 parts by weight or more, more preferably about 20 parts by weight or more, further preferably about 25 parts by weight or more, particularly Preferably it is about 30 parts by weight or more.
- the upper limit of the content of the tackifier resin is not particularly limited.
- the content is not more than about 80 parts by weight, preferably not more than about 60 parts by weight, more preferably not more than about 60 parts by weight, based on 100 parts by weight of the base polymer. It is about 55 parts by weight or less, more preferably about 50 parts by weight or less (for example, about 45 parts by weight or less), and may be about 40 parts by weight or less (for example, about 35 parts by weight or less).
- the pressure-sensitive adhesive composition (and thus the pressure-sensitive adhesive layer) disclosed herein may contain a (meth) acrylic oligomer from the viewpoint of improving the adhesive strength.
- a (meth) acrylic oligomer the Tg of a copolymer corresponding to the composition of the monomer component (typically, generally corresponds to the Tg of an acrylic polymer contained in an adhesive formed from the adhesive composition) ) Is preferably used.
- the adhesive strength of the pressure-sensitive adhesive can be improved.
- the (meth) acrylic oligomer preferably has a Tg of about 0 ° C to about 300 ° C, preferably about 20 ° C to about 300 ° C, more preferably about 40 ° C to about 300 ° C.
- Tg is within the above range, the adhesive force can be suitably improved.
- the Tg of the (meth) acrylic oligomer is about 30 ° C. or more, more preferably about 50 ° C. or more (eg, about 60 ° C. or more), and the initial adhesion
- the temperature is preferably about 200 ° C. or less, more preferably about 150 ° C.
- the Tg of the (meth) acrylic oligomer is a value calculated based on the Fox equation, similarly to the Tg of the copolymer corresponding to the composition of the monomer component.
- the weight average molecular weight (Mw) of the (meth) acrylic oligomer can be typically from about 1000 to less than about 30,000, preferably from about 1500 to less than about 20,000, more preferably from about 2,000 to less than about 10,000. It is preferable that Mw is within the above range, since good adhesion and holding characteristics can be obtained.
- the Mw of the (meth) acrylic oligomer is about 2500 or more (for example, about 3000 or more) from the viewpoint of deformation resistance against a continuous load in the Z-axis direction. It is preferably about 7000 or less, more preferably about 5000 or less (eg, about 4500 or less, even about 400 or less).
- the Mw of the (meth) acrylic oligomer can be measured by gel permeation chromatography (GPC) and determined as a value in terms of standard polystyrene. Specifically, it is measured by using TSKgel GMH-H (20) ⁇ 2 as a column with HPLC 8020 manufactured by Tosoh Corporation with a tetrahydrofuran solvent at a flow rate of about 0.5 mL / min.
- GPC gel permeation chromatography
- Examples of the monomer constituting the (meth) acrylic oligomer include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, heptyl (meth) acrylate, octyl ( (Meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isode
- (Meth) acrylic oligomers include alkyl (meth) acrylates having a branched alkyl group such as isobutyl (meth) acrylate and t-butyl (meth) acrylate; cyclohexyl (meth) acrylate and isobornyl (meth) acrylate; Ester of (meth) acrylic acid and alicyclic alcohol such as dicyclopentanyl (meth) acrylate (alicyclic hydrocarbon group-containing (meth) acrylate); phenyl (meth) acrylate and benzyl (meth) acrylate
- an acrylic monomer having a relatively bulky structure as a monomer unit such as a (meth) acrylate having a cyclic structure such as an aryl (meth) acrylate, further increases the adhesiveness of the pressure-sensitive adhesive layer.
- Alkyl (meth) acrylate having a structure or an ester with an alicyclic alcohol ((meth) acrylate containing an alicyclic hydrocarbon group) can be suitably used as a monomer constituting the (meth) acrylic oligomer.
- the above-mentioned branched alkyl (meth) acrylate, alicyclic hydrocarbon group (meth) acrylate, and aryl (meth) acrylate all correspond to the (meth) acrylate monomer in the technology disclosed herein.
- the alicyclic hydrocarbon group can be a saturated or unsaturated alicyclic hydrocarbon group.
- the ratio of the (meth) acrylate monomer (for example, the (meth) acrylate containing an alicyclic hydrocarbon group) to all the monomer components constituting the (meth) acrylic oligomer is typically more than 50% by weight, and is preferably Is 60% by weight or more, more preferably 70% by weight or more (for example, 80% by weight or more, further 90% by weight or more).
- the (meth) acrylic oligomer has a monomer composition consisting essentially of only a (meth) acrylate monomer.
- a functional group-containing monomer can be used in addition to the above (meth) acrylate monomer.
- Preferred examples of the functional group-containing monomer include monomers having a nitrogen atom-containing ring (typically a nitrogen atom-containing heterocycle) such as N-vinyl-2-pyrrolidone and N-acryloylmorpholine; N, N-dimethylamino Amino group-containing monomers such as ethyl (meth) acrylate; amide group-containing monomers such as N, N-diethyl (meth) acrylamide; carboxy-containing monomers such as AA and MAA; hydroxyl-containing monomers such as 2-hydroxyethyl (meth) acrylate And a monomer.
- These functional group-containing monomers can be used alone or in combination of two or more. Among them, carboxy group-containing monomers are preferred, and AA is particularly preferred.
- the proportion of the functional group-containing monomer (for example, a carboxy group-containing monomer such as AA) in the total monomer component is about 1% by weight.
- the amount is suitably at least 2, preferably at least 2% by weight, more preferably at least 3% by weight, and is suitably at most about 15% by weight, preferably at most 10% by weight, more preferably at most 10% by weight. 7% by weight or less.
- (Meth) acrylic oligomers can be formed by polymerizing the constituent monomer components.
- the polymerization method and polymerization mode are not particularly limited, and conventionally known various polymerization methods (for example, solution polymerization, emulsion polymerization, bulk polymerization, photopolymerization, radiation polymerization, and the like) can be adopted in appropriate modes.
- the type of the polymerization initiator for example, an azo-based polymerization initiator such as AIBN
- AIBN azo-based polymerization initiator
- the amount of the chain transfer agent, such as n-dodecyl mercaptan is appropriately set based on common general technical knowledge so as to have a desired molecular weight, and thus detailed description is omitted here.
- suitable (meth) acrylic oligomers include, for example, dicyclopentanyl methacrylate (DCPMA), cyclohexyl methacrylate (CHMA), isobornyl methacrylate (IBXMA), isobornyl acrylate (IBXA),
- DCPA cyclopentanyl acrylate
- ADMA 1-adamantyl methacrylate
- ADA 1-adamantyl acrylate
- homopolymers copolymers of CHMA and isobutyl methacrylate (IBMA)
- copolymers of CHMA and IBXMA Polymer, copolymer of CHMA and acryloylmorpholine (ACMO), copolymer of CHMA and diethylacrylamide (DEAA), copolymer of CHMA and AA, ADA and methyl methacrylate (MMA)
- DCPMA dicyclopentanyl methacrylate
- CHMA cyclohexyl methacrylate
- the content of the (meth) acrylic oligomer is preferably about 5 parts by weight or more, more preferably about 8 parts by weight or more, and still more preferably about 5 parts by weight or more. It is at least 10 parts by weight, particularly preferably at least about 12 parts by weight.
- the content of the (meth) acrylic oligomer is suitably less than 50 parts by weight (for example, less than 40 parts by weight), and is preferably Is less than 30 parts by weight, more preferably about 25 parts by weight or less, still more preferably about 20 parts by weight or less, and may be about 10 parts by weight or less, about 3 parts by weight or less (for example, about 1 part by weight or less) May be.
- the technology disclosed herein can be implemented in a mode in which the pressure-sensitive adhesive layer does not substantially contain a (meth) acrylic oligomer.
- the pressure-sensitive adhesive composition used to form the pressure-sensitive adhesive preferably contains a crosslinking agent.
- a crosslinking agent By including a crosslinking agent in the pressure-sensitive adhesive composition, a crosslinked structure is introduced into the pressure-sensitive adhesive.
- the type of the crosslinking agent is not particularly limited, and examples thereof include an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, an oxazoline-based crosslinking agent, an aziridine-based crosslinking agent, a melamine-based crosslinking agent, a peroxide-based crosslinking agent, a urea-based crosslinking agent, and a metal.
- An alkoxide-based crosslinking agent, a metal chelate-based crosslinking agent, a metal salt-based crosslinking agent, a carbodiimide-based crosslinking agent, an amine-based crosslinking agent, or the like can be appropriately selected and used.
- the crosslinking agent one kind can be used alone, or two or more kinds can be used in combination.
- Isocyanate-based cross-linking agents are preferred from the viewpoint of adhesion to the adherend and impact resistance, and epoxy-based cross-linking agents are preferred from the viewpoint of adhesion performance (including layer shape retention). According to the technology disclosed herein, a high-performance pressure-sensitive adhesive sheet can be provided without using an epoxy-based cross-linking agent or reducing the amount of use thereof.
- an isocyanate-based cross-linking agent as a main cross-linking agent component, adhesion to an adherend can be enhanced, and impact resistance can be improved.
- the use of an isocyanate-based crosslinking agent is advantageous, for example, from the viewpoint of improving the adhesive strength to an adherend made of a polyester resin such as PET.
- epoxy-based crosslinking agent a compound having two or more epoxy groups in one molecule can be used without any particular limitation. Epoxy crosslinkers having 3 to 5 epoxy groups in one molecule are preferred. Epoxy-based crosslinking agents can be used alone or in combination of two or more.
- epoxy-based crosslinking agent examples include, for example, N, N, N ', N'-tetraglycidyl-m-xylenediamine, 1,3-bis (N, N-diglycidylaminomethyl ) Cyclohexane, 1,6-hexanediol diglycidyl ether, polyethylene glycol diglycidyl ether, polyglycerol polyglycidyl ether and the like.
- Commercial products of epoxy cross-linking agents include trade names "TETRAD-C” and "TETRAD-X” manufactured by Mitsubishi Gas Chemical Company, "Epiclon CR-5L” manufactured by DIC, and Nagase ChemteX Corporation. And “TEPIC-G” (trade name, manufactured by Nissan Chemical Industries, Ltd.).
- an epoxy-based crosslinking agent When an epoxy-based crosslinking agent is used, its amount is not particularly limited, and may be, for example, 3 parts by weight or less based on 100 parts by weight of the base polymer. From the viewpoint of improving the adhesion to the adherend or the substrate and the anchoring power, the amount of the epoxy-based cross-linking agent is preferably 1 part by weight or less, more preferably 0.5 part by weight or less (typically 100 parts by weight of the base polymer). Is preferably 0.2 parts by weight or less, for example, 0.1 parts by weight or less, more preferably 0.05 parts by weight or less, and may be 0.03 parts by weight or less (for example, 0.02 parts by weight or less). .
- the amount of the epoxy-based crosslinking agent can be set to 0.001 part by weight or more (for example, 0.005 part by weight or more) based on 100 parts by weight of the base polymer.
- polyfunctional isocyanate refers to a compound having an average of two or more isocyanate groups per molecule, including a compound having an isocyanurate structure
- the isocyanate-based cross-linking agents can be used alone or in combination of two or more.
- polyfunctional isocyanates include aliphatic polyisocyanates, alicyclic polyisocyanates, aromatic polyisocyanates, and the like.
- Specific examples of the aliphatic polyisocyanate include 1,2-ethylene diisocyanate; tetramethylene diisocyanate such as 1,2-tetramethylene diisocyanate, 1,3-tetramethylene diisocyanate, and 1,4-tetramethylene diisocyanate; Hexamethylene diisocyanate such as hexamethylene diisocyanate, 1,3-hexamethylene diisocyanate, 1,4-hexamethylene diisocyanate, 1,5-hexamethylene diisocyanate, 1,6-hexamethylene diisocyanate, 2,5-hexamethylene diisocyanate; 2-methyl-1,5-pentane diisocyanate, 3-methyl-1,5-pentane diisocyanate, lysine diisocyanate and the like.
- alicyclic polyisocyanate examples include isophorone diisocyanate; cyclohexyl diisocyanate such as 1,2-cyclohexyl diisocyanate, 1,3-cyclohexyl diisocyanate, and 1,4-cyclohexyl diisocyanate; 1,2-cyclopentyl diisocyanate; -Cyclopentyl diisocyanate such as cyclopentyl diisocyanate; hydrogenated xylylene diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated tetramethyl xylene diisocyanate, 4,4'-dicyclohexyl methane diisocyanate, and the like.
- aromatic polyisocyanates include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, and 2,2′-diphenylmethane diisocyanate.
- 4,4'-diphenyl ether diisocyanate 2,2'-diphenylpropane-4,4'-diisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate , 4,4'-diphenylpropane diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, naphthylene-1,4-diisocyanate, naphthylene-1,5-diisocyanate, 3,3'-dimeth Shi diphenyl-4,4'-diisocyanate, xylylene-1,4-diisocyanate, xylylene-1,3-diisocyanate.
- ⁇ Preferred polyfunctional isocyanates include polyfunctional isocyanates having an average of three or more isocyanate groups per molecule.
- a trifunctional or higher functional isocyanate is a bifunctional or trifunctional or higher functional isocyanate multimer (typically a dimer or trimer), a derivative (for example, a polyhydric alcohol and a bifunctional or higher polyfunctional isocyanate). Addition reaction product), a polymer or the like.
- dimer or trimer of diphenylmethane diisocyanate isocyanurate of hexamethylene diisocyanate (trimer adduct of isocyanurate structure), a reaction product of trimethylolpropane and tolylenediisocyanate, trimethylolpropane and hexamer
- polyfunctional isocyanates such as a reaction product with methylene diisocyanate, polymethylene polyphenyl isocyanate, polyether polyisocyanate, and polyester polyisocyanate.
- an isocyanate-based cross-linking agent When an isocyanate-based cross-linking agent is used, its use amount is not particularly limited. For example, it is more than 0 parts by weight and about 10 parts by weight or less (typically 0.01 to 10 parts by weight) based on 100 parts by weight of the base polymer. It can be. From the viewpoints of coexistence of cohesion and adhesion, impact resistance, and the like, the amount of the isocyanate-based crosslinking agent with respect to 100 parts by weight of the base polymer is preferably about 0.5 part by weight or more, more preferably about 1 part by weight or more, More preferably, it is about 1.5 parts by weight or more.
- the amount of the isocyanate-based crosslinking agent is preferably about 8 parts by weight or less, more preferably about 6 parts by weight or less, and about 5 parts by weight or less based on 100 parts by weight of the base polymer. It is particularly preferably about 4 parts by weight or less (for example, about 3 parts by weight or less).
- the technique disclosed herein is preferably implemented in a mode in which an epoxy-based crosslinking agent and an isocyanate-based crosslinking agent are used in combination.
- the relationship between the content of the epoxy-based crosslinking agent and the content of the isocyanate-based crosslinking agent is not particularly limited.
- the content of the epoxy-based crosslinking agent can be, for example, approximately 1/50 or less of the content of the isocyanate-based crosslinking agent. From the viewpoint of more preferably achieving a good balance between the adhesion to the adherend and the base material and the cohesive force, the content of the epoxy-based crosslinking agent is appropriately set to be about 1/75 or less of the content of the isocyanate-based crosslinking agent.
- the content of the epoxy-based crosslinking agent is approximately 1/1000 or more of the content of the isocyanate-based crosslinking agent, For example, it is appropriate to set it to about 1/500 or more.
- the total amount of the crosslinking agent is not particularly limited, and is, for example, about 0.005 parts by weight or more (for example, 0.01 parts by weight or more, typically 0.1 parts by weight or more) based on 100 parts by weight of the base polymer. Can be selected from a range of about 10 parts by weight or less (for example, about 8 parts by weight or less, preferably about 5 parts by weight or less).
- additives In the pressure-sensitive adhesive composition, in addition to the components described above, if necessary, a leveling agent, a crosslinking aid, a plasticizer, a softener, an antistatic agent, an antioxidant, an ultraviolet absorber, an antioxidant, and a light stabilizer And the like, various additives that are common in the field of pressure-sensitive adhesives may be included. As such various additives, conventionally known ones can be used in a conventional manner, and do not particularly characterize the present invention, and thus detailed description thereof will be omitted.
- the pressure-sensitive adhesive layer (layer comprising a pressure-sensitive adhesive) disclosed herein is formed from a water-based pressure-sensitive adhesive composition, a solvent-type pressure-sensitive adhesive composition, a hot-melt-type pressure-sensitive adhesive composition, and an active energy ray-curable pressure-sensitive adhesive composition.
- Pressure-sensitive adhesive layer refers to a pressure-sensitive adhesive composition in the form of a pressure-sensitive adhesive (pressure-sensitive adhesive layer-forming component) in a solvent containing water as a main component (aqueous solvent), and is typically dispersed in water.
- a so-called type pressure-sensitive adhesive composition (a composition in which at least a part of the pressure-sensitive adhesive is dispersed in water).
- the solvent-based pressure-sensitive adhesive composition refers to a pressure-sensitive adhesive composition in a form containing a pressure-sensitive adhesive in an organic solvent.
- the technology disclosed herein can be preferably implemented in a mode including an adhesive layer formed from a solvent-based adhesive composition from the viewpoint of adhesive properties and the like.
- the pressure-sensitive adhesive layer disclosed herein can be formed by a conventionally known method. For example, a method of forming a pressure-sensitive adhesive layer by applying a pressure-sensitive adhesive composition to a surface having peelability (peeling surface) or a non-peelable surface and drying the pressure-sensitive adhesive composition can be adopted. In the pressure-sensitive adhesive sheet having a substrate, for example, a method (direct method) of forming a pressure-sensitive adhesive layer by directly applying (typically, applying) the pressure-sensitive adhesive composition to the substrate and drying the pressure-sensitive adhesive composition is adopted. be able to.
- a method in which an adhesive composition is applied to a surface having a releasability (release surface) and dried to form an adhesive layer on the surface, and the adhesive layer is transferred to a substrate. May be adopted. From the viewpoint of productivity, the transfer method is preferable.
- the release surface the surface of a release liner, the back surface of a substrate subjected to a release treatment, or the like can be used.
- the pressure-sensitive adhesive layer disclosed herein is typically formed continuously, but is not limited to such a form.For example, a point-like, stripe-like or other regular or random pattern The formed pressure-sensitive adhesive layer may be used.
- the application of the pressure-sensitive adhesive composition can be performed using a conventionally known coater such as a gravure roll coater, a die coater, and a bar coater.
- the pressure-sensitive adhesive composition may be applied by impregnation, curtain coating, or the like.
- the drying of the pressure-sensitive adhesive composition is performed under heating.
- the drying temperature can be, for example, about 40 to 150 ° C., and preferably about 60 to 130 ° C.
- aging may be further performed for the purpose of adjusting the migration of components in the pressure-sensitive adhesive layer, progressing the cross-linking reaction, alleviating distortion that may be present in the pressure-sensitive adhesive layer, and the like.
- the thickness of the pressure-sensitive adhesive layer is not particularly limited. From the viewpoint of avoiding the pressure-sensitive adhesive sheet from being excessively thick, the thickness of the pressure-sensitive adhesive layer is suitably about 100 ⁇ m or less, preferably about 70 ⁇ m or less, more preferably about 60 ⁇ m or less, and still more preferably about 50 ⁇ m or less. .
- the lower limit of the thickness of the pressure-sensitive adhesive layer is not particularly limited, but is preferably about 3 ⁇ m or more, preferably about 10 ⁇ m or more, more preferably about 20 ⁇ m or more (for example, from the viewpoint of adhesion to an adherend). (Approximately 30 ⁇ m or more).
- the pressure-sensitive adhesive sheet disclosed herein may be a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer having the above thickness on both sides of a substrate. Further, in a double-sided PSA sheet with a substrate having a first PSA layer and a second PSA layer on each side of the substrate, the first PSA layer and the second PSA layer have the same thickness. Or different thicknesses from each other.
- the gel fraction of the pressure-sensitive adhesive layer disclosed herein is, for example, 20% by weight. It is appropriate that the content is 30% or more, and preferably 35% or more. By increasing the gel fraction of the pressure-sensitive adhesive layer within an appropriate range, the deformation resistance to a continuous load in the Z-axis direction tends to be easily obtained. In the technology disclosed herein, it is more preferable that the pressure-sensitive adhesive layer has a gel fraction of 40% or more. The gel fraction may be 45% or more, 50% or more, for example, 55% or more.
- the gel fraction of the pressure-sensitive adhesive layer is preferably 90% or less, more preferably 80% or less, further preferably 70% or less (for example, 65% or less), and more preferably 60% or less. Or 50% or less.
- the pressure-sensitive adhesive sheet disclosed herein is a double-sided pressure-sensitive adhesive sheet with a substrate
- the gel fractions of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer may be the same or different.
- the pressure-sensitive adhesive sheet disclosed herein includes a foam base material.
- the pressure-sensitive adhesive sheet is configured as a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer on at least one surface of a foam base material.
- the foam base material is a base material having a portion having cells (cell structure), and typically includes at least one layered foam (foam layer). Containing base material
- the foam substrate may be a substrate composed of one or more foam layers.
- the foam base material may be, for example, a base material substantially constituted by only one or two or more foam layers.
- a preferable example of the foam substrate in the technology disclosed herein is a foam substrate including a single-layer (one layer) foam layer.
- the density D of the foam base material (refers to the apparent density; the same applies hereinafter unless otherwise specified) is not particularly limited, and may be, for example, about 0.1 to 0.9 g / cm 3 . From the viewpoint of impact resistance, the density D of the foam base material is suitably about 0.8 g / cm 3 or less, and preferably about 0.7 g / cm 3 or less (for example, about 0.6 g / cm 3 or less). . In one embodiment, the density D of the foam substrate may be less than 0.5 g / cm 3, may be less than 0.45 g / cm 3.
- the density D of the foam base material is preferably about 0.12 g / cm 3 or more, more preferably about 0.15 g / cm 3 or more, and about 0.2 g / cm 3 or more ( For example, it is more preferably about 0.3 g / cm 3 or more.
- the density D of the foam substrate may be about 0.4 g / cm 3 or more, and may be about 0.5 g / cm 3 or more (for example, more than 0.5 g / cm 3 ), Furthermore, it may be 0.55 g / cm 3 or more.
- the density D (apparent density) of the foam base material can be measured in accordance with JIS K6767.
- the average cell diameter of the foam base material is not particularly limited, but is preferably about 300 ⁇ m or less, more preferably about 200 ⁇ m or less, and still more preferably about 150 ⁇ m or less from the viewpoint of stress dispersion.
- the average cell size of the foam substrate may be about 120 ⁇ m or less, and may be about 100 ⁇ m or less (typically about 90 ⁇ m or less, for example, about 80 ⁇ m or less, and even about 70 ⁇ m or less).
- the lower limit of the average bubble diameter is not particularly limited, and is suitably about 10 ⁇ m or more, preferably about 20 ⁇ m or more, more preferably about 30 ⁇ m or more, and still more preferably about 40 ⁇ m or more (for example, about 50 ⁇ m or more).
- the average bubble diameter may be greater than or equal to 55 ⁇ m, and may be greater than or equal to 60 ⁇ m. Increasing the average bubble diameter tends to improve impact resistance.
- the average cell diameter refers to an average cell diameter in terms of a true sphere obtained by observing a cross section of the foam base material with an electron microscope.
- the bubbles contained in the foam base material preferably have a shape that is relatively close to a circle in plan view of the foam base material. That is, it is preferable that the average cell diameter in the flow direction (hereinafter also referred to as “MD”) of the foam base material and the average cell diameter in the width direction (hereinafter also referred to as “CD”) do not differ too much.
- the degree of the deviation of the shape of the cells from the circular shape is determined by the ratio of the average cell diameter (MD average cell diameter) for MD to the average cell diameter (CD average cell diameter) for CD of the foam base material, that is,
- the “aspect ratio (MD / CD)” represented by the equation can be grasped as an index. When the aspect ratio (MD / CD) is closer to 1, it can be said that the shape of the bubbles contained in the foam base material in plan view is closer to a circle.
- Aspect ratio (MD / CD) MD average cell diameter / CD average cell diameter
- the aspect ratio (MD / CD) of cells contained in the foam base material is preferably 0.7 or more, more preferably 0.75 or more, and further preferably 0.8 or more. Or more, for example, 0.85 or more. In one embodiment, the aspect ratio may be 0.9 or higher, and may be 0.95 or higher (eg, approximately 1.0 or higher). Further, the aspect ratio (MD / CD) is preferably 1.3 or less, more preferably 1.25 or less, further preferably 1.2 or less, and for example, may be 1.15 or less. When the aspect ratio (MD / CD) is not too small, the handleability of the pressure-sensitive adhesive sheet using the foam base material can be improved. It is appropriate that the aspect ratio (MD / CD) is not too large than 1.
- the MD of the foam base material indicates the extrusion direction in the production process of the foam base material.
- the MD of a long foam base material such as a tape shape coincides with the long direction.
- the CD of the foam substrate refers to a direction orthogonal to the MD of the foam substrate and along the surface of the foam substrate.
- the thickness direction (hereinafter also referred to as “VD”) of the foam base material is a direction orthogonal to both the MD and the CD.
- the average cell diameter in each direction of the foam base material is controlled, for example, by adjusting the composition of the foam base material (eg, the amount of the foaming agent used) and the production conditions (conditions in the foaming step, stretching step, etc.). be able to.
- the relationship between the 10% compressive strength C 10 [kPa] and the 30% compressive strength C 30 [kPa] of the foam base material in the technology disclosed herein is as follows: (C 30 / C 10 ) ⁇ 5. 0; can be preferably adopted.
- the 10% compressive strength of the foam base material is determined by stacking the foam base material cut into a square shape of 30 mm square, sandwiching a measurement sample having a thickness of about 2 mm between a pair of flat plates, Refers to the load (load at a compression ratio of 10%) when compressed by a thickness corresponding to 10% of the thickness of the sample. That is, it refers to the load when the measurement sample is compressed to a thickness corresponding to 90% of the original thickness.
- the 30% compressive strength C 30 [kPa] and the 25% compressive strength C 25 [kPa] to be described later are obtained when the measurement sample is compressed by a thickness corresponding to 30% or 25% of the original thickness.
- the compressive strength of the foam base material at an arbitrary compressibility is measured according to JIS K6767. As a specific measurement procedure, the measurement sample was set at the center of the pair of flat plates, and the plate was continuously compressed to an arbitrary compression ratio by reducing the interval between the flat plates. Measure the load after the passage.
- the compressive strength of the foam base material can be controlled by, for example, the degree of crosslinking and density of the material constituting the foam base material, the size and shape of the cells, and the like.
- the compression strength ratio (C 30 / C 10 ) is small means that the difference in the degree of compression has little effect on the compression strength.
- the adhesive surface of the adhesive sheet has irregularities such as steps or scratches
- the width of the adhesive sheet is partially different, or when a part of the adhesive part by the adhesive sheet receives a greater stress than other parts.
- a part of the pressure-sensitive adhesive sheet may be compressed more than the other part.
- the pressure-sensitive adhesive sheet is reduced in width, the difference in the degree of compression due to the above-mentioned step or partial difference in width tends to be more remarkable.
- (C 30 / C 10 ) is more preferably equal to or less than 4.5, and further preferably equal to or less than 4.0.
- (C 30 / C 10 ) may be 3.5 or less.
- the lower limit of (C 30 / C 10 ) is not particularly limited, but is suitably, for example, 2.5 or more, and may be 3.0 or more.
- the 25% compressive strength C 25 of the foam base material is not particularly limited, and may be, for example, 20 kPa or more (typically 40 kPa or more).
- C 25 is suitably at least 250 kPa, preferably at least 300 kPa (e.g. 400kPa or higher) may be more than 500 kPa, or may be a more 700 kPa (e.g. 900kPa or less).
- An adhesive sheet provided with such a foam base material can exhibit good durability against impacts such as dropping. For example, the adhesive sheet may be better prevented from being broken by impact.
- the upper limit of the C 25 is not particularly limited, 1300 kPa or less (eg 1200kPa or less) are suitable.
- C 25 may be less than or equal to 1000 kPa.
- the relationship between C 25 [kPa] and the apparent density D [g / cm 3 ] is expressed by the following formula: 150 ⁇ C 25 ⁇ D ⁇ 400 (for example, 200 ⁇ C 25 ⁇ D ⁇ 350, preferably 240 ⁇ C 25 ⁇ D ⁇ According to the pressure-sensitive adhesive sheet provided with the foam base material satisfying (300); better results can be realized.
- the C 25 of the foam substrate can be between 20 kPa and 200 kPa (typically between 30 kPa and 150 kPa, for example between 40 kPa and 120 kPa). Since the pressure-sensitive adhesive sheet including such a foam base material has a low compressive strength for its density, it can be excellent in cushioning property even in a narrow width. For example, peeling of the pressure-sensitive adhesive sheet can be better prevented by absorbing the drop impact by the foam base material.
- C 25 [kPa] and apparent density D [g / cm 3 ] is expressed by the following formula: 100 ⁇ C 25 / D ⁇ 400 (for example, 150 ⁇ C 25 / D ⁇ 350, preferably 200 ⁇ C 25 / D ⁇ According to the pressure-sensitive adhesive sheet provided with the foam base material satisfying (300); better results can be realized.
- the tensile elongation of the foam base material is not particularly limited.
- a foam base material having a tensile elongation in the machine direction (MD) of 200% to 800% (more preferably 400% to 600%) can be suitably used.
- a foam base material having a tensile elongation in the width direction (TD) of 50% to 800% (more preferably 200% to 500%) is preferable.
- the elongation of the foam base material is measured according to JIS @ K # 6767.
- the elongation of the foam base material can be controlled, for example, by the degree of crosslinking, the apparent density (expansion ratio), and the like.
- the tensile strength (tensile strength) of the foam base material is not particularly limited.
- a foam base material having a tensile strength in the flow direction (MD) of 5 MPa to 35 MPa (preferably 10 MPa to 30 MPa) can be suitably used.
- a foam base material having a tensile strength in the width direction (TD) of 1 MPa to 25 MPa (more preferably 5 MPa to 20 MPa) is preferable.
- the tensile strength of the foam base material is measured according to JIS @ K # 6767.
- the tensile strength of the foam base material can be controlled by, for example, the degree of crosslinking, the apparent density (expansion ratio), and the like.
- the material of the foam base material is not particularly limited.
- a foam base material including a foam layer formed of a foam of a plastic material (plastic foam) is preferable.
- the plastic material (including the rubber material) for forming the plastic foam is not particularly limited, and can be appropriately selected from known plastic materials.
- One type of plastic material can be used alone, or two or more types can be used in appropriate combination.
- plastic foam examples include polyolefin resin foams such as polyethylene foams and polypropylene foams; polyester-based foams such as polyethylene terephthalate foams, polyethylene naphthalate foams, and polybutylene terephthalate foams.
- Resin foam polyvinyl chloride resin foam such as polyvinyl chloride foam; vinyl acetate resin foam; polyphenylene sulfide resin foam; aliphatic polyamide (nylon) resin foam, wholly aromatic Polyamide (Aramid) resin foam such as amide resin foam; Polyimide resin foam; Polyetheretherketone (PEEK) foam; Styrene resin foam such as polystyrene foam; Polyurethane Urethane-based resin foams such as resin foams; and the like That. Also, a rubber-based resin foam such as a polychloroprene rubber foam may be used as the plastic foam.
- a rubber-based resin foam such as a polychloroprene rubber foam may be used as the plastic foam.
- polyolefin foam As a preferable foam, a polyolefin resin foam (hereinafter, also referred to as “polyolefin foam”) is exemplified.
- plastic material ie, polyolefin resin
- various known or commonly used polyolefin resins can be used without particular limitation.
- polyethylene such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and high-density polyethylene (HDPE), polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer and the like can be mentioned.
- LLDPE low-density polyethylene
- LLDPE linear low-density polyethylene
- HDPE high-density polyethylene
- polypropylene polypropylene
- ethylene-propylene copolymer ethylene-vinyl acetate copolymer and the like
- LLDPE include Ziegler-Natta catalyst linear low density polyethylene,
- the foam base material in the technology disclosed herein include a polyethylene-based foam base material substantially composed of a polyethylene-based resin foam from the viewpoints of impact resistance, waterproofness, dustproofness, and the like. And a polyolefin-based foam base material such as a polypropylene-based foam base material substantially composed of a polypropylene-based resin foam.
- the polyethylene-based resin refers to a resin containing ethylene as a main monomer (that is, a main component of the monomer).
- ethylene-based resins having an ethylene copolymerization ratio of more than 50% by weight In addition to HDPE, LDPE, LLDPE, etc., ethylene-based resins having an ethylene copolymerization ratio of more than 50% by weight.
- a polyethylene-based foam base material can be preferably adopted.
- the method for producing the plastic foam is not particularly limited, and various known methods can be appropriately employed. For example, it can be manufactured by a method including a molding step, a crosslinking step, and a foaming step of the plastic material or the plastic foam. In addition, a stretching step may be included as necessary.
- the method for crosslinking the plastic foam include a chemical crosslinking method using an organic peroxide or the like, and an ionizing radiation crosslinking method of irradiating with ionizing radiation, and these methods can be used in combination.
- the ionizing radiation include an electron beam, ⁇ -ray, ⁇ -ray, and ⁇ -ray.
- the dose of the ionizing radiation is not particularly limited, and can be set to an appropriate irradiation dose in consideration of the target physical properties (for example, the degree of crosslinking) of the foam base material.
- fillers inorganic fillers, organic fillers, etc.
- antioxidants antioxidants
- ultraviolet absorbers antistatic agents
- lubricants plasticizers
- flame retardants Various additives such as a surfactant may be blended.
- the foam substrate in the technology disclosed herein is colored in order to exhibit desired design properties and optical characteristics (for example, light-shielding properties, light-reflecting properties, etc.) in the pressure-sensitive adhesive sheet provided with the foam substrate. You may.
- a known organic or inorganic coloring agent can be used alone or in an appropriate combination of two or more.
- the visible light transmittance of the foam base material is not particularly limited, but may be 0% to 15% similarly to the visible light transmittance of the pressure-sensitive adhesive sheet described later. Is more preferable, and more preferably 0% to 10%.
- the visible light reflectance of the foam base material is preferably 20% to 100%, more preferably the visible light reflectance of the pressure-sensitive adhesive sheet. It is 25% to 100%.
- the visible light transmittance of the foam base material was measured using a spectrophotometer (for example, a spectrophotometer manufactured by Hitachi High-Technologies Corporation, Model “U-4100”) at a wavelength of 550 nm. It can be determined by measuring the intensity of light emitted from the surface side and transmitted to the other surface side.
- the visible light reflectance of the foam substrate can be determined by measuring the intensity of light reflected by irradiating one surface of the foam substrate at a wavelength of 550 nm using the above-described spectrophotometer.
- the visible light transmittance and the visible light reflectance of the pressure-sensitive adhesive sheet can be obtained by the same method.
- the foam base material is preferably colored black.
- Black is preferably L * (brightness) defined by the L * a * b * color system, preferably 35 or less (eg, 0 to 35), more preferably 30 or less (eg, 0 to 30).
- a * and b * defined by the L * a * b * color system can be appropriately selected according to the value of L *.
- a * and b * are not particularly limited, both are preferably in the range of ⁇ 10 to 10 (more preferably ⁇ 5 to 5, more preferably ⁇ 2.5 to 2.5).
- it is preferable that both a * and b * are 0 or substantially 0.
- L *, a *, and b * defined in the L * a * b * color system are colorimeters (for example, a colorimeter manufactured by Minolta, product name "CR-200"). )).
- the L * a * b * color system is a color space recommended by the International Commission on Illumination (CIE) in 1976, and is a color space called the CIE 1976 (L * a * b *) color system. Means that.
- the L * a * b * color system is defined in JIS Z8729 in Japanese Industrial Standards.
- black colorant used to color the foam base material black examples include carbon black (furnace black, channel black, acetylene black, thermal black, lamp black, etc.), graphite, copper oxide, manganese dioxide, aniline Black, perylene black, titanium black, cyanine black, activated carbon, ferrite (non-magnetic ferrite, magnetic ferrite, etc.), magnetite, chromium oxide, iron oxide, molybdenum disulfide, chromium complex, composite oxide black pigment, anthraquinone organic black Dyes and the like can be used.
- carbon black is exemplified.
- the amount of the black colorant used is not particularly limited, and may be appropriately adjusted so as to provide desired optical characteristics.
- the foam base is preferably colored white.
- L * (lightness) defined by the L * a * b * color system is preferably 87 or more (for example, 87 to 100), more preferably 90 or more (for example, 90 to 100).
- a * and b * defined in the L * a * b * color system can be appropriately selected according to the value of L *.
- a * and b * for example, both are preferably in the range of ⁇ 10 to 10 (more preferably ⁇ 5 to 5, more preferably ⁇ 2.5 to 2.5).
- it is preferable that both a * and b * are 0 or substantially 0.
- Examples of the white colorant used when coloring the foam base material in white include titanium oxide (titanium dioxide such as rutile-type titanium dioxide and anatase-type titanium dioxide), zinc oxide, aluminum oxide, silicon oxide, and zirconium oxide. , Magnesium oxide, calcium oxide, tin oxide, barium oxide, cesium oxide, yttrium oxide, magnesium carbonate, calcium carbonate (light calcium carbonate, heavy calcium carbonate, etc.), barium carbonate, zinc carbonate, aluminum hydroxide, calcium hydroxide, Magnesium hydroxide, zinc hydroxide, aluminum silicate, magnesium silicate, calcium silicate, barium sulfate, calcium sulfate, barium stearate, zinc white, zinc sulfide, talc, silica, alumina, clay, kaolin, titanium phosphate, mica, gypsum, why Inorganic white colorants such as carbon, diatomaceous earth, bentonite, lithopone, zeolite, sericite,
- the surface of the foam base material may be subjected to an appropriate surface treatment as needed.
- the surface treatment may be, for example, a chemical or physical treatment for increasing the adhesion to an adjacent material (for example, an adhesive layer).
- Examples of such surface treatment include corona discharge treatment, chromic acid treatment, ozone exposure, flame exposure, ultraviolet irradiation treatment, plasma treatment, and application of a primer (primer).
- the thickness of the foam base material is not particularly limited, and can be appropriately set according to the strength and flexibility of the pressure-sensitive adhesive sheet, the purpose of use, and the like. From the viewpoint of reducing the thickness of the joining portion, the thickness of the foam base material is suitably about 700 ⁇ m or less, preferably about 400 ⁇ m or less, and more preferably about 300 ⁇ m or less.
- the technology disclosed herein can be preferably implemented in a mode in which the thickness of the foam base material is approximately 200 ⁇ m or less (for example, 180 ⁇ m or less, further 160 ⁇ m or less).
- the thickness of the foam base material is suitably about 50 ⁇ m or more, preferably about 60 ⁇ m or more, and more preferably about 70 ⁇ m or more (for example, about 80 ⁇ m or more).
- the technology disclosed herein can be preferably implemented in a mode in which the thickness of the foam base material is about 100 ⁇ m or more (for example, more than 100 ⁇ m, preferably 120 ⁇ m or more, for example, 130 ⁇ m or more).
- the thickness of the foam base material is increased, the impact resistance is also improved. For example, a desired impact resistance tends to be exhibited even in a narrow width configuration.
- a release liner can be used when forming a pressure-sensitive adhesive layer, preparing a pressure-sensitive adhesive sheet, storing, distributing, or shaping the pressure-sensitive adhesive sheet before use.
- the release liner is not particularly limited.
- a release liner having a release treatment layer on the surface of a liner substrate such as a resin film or paper, a fluoropolymer (such as polytetrafluoroethylene) or a polyolefin resin (polyethylene,
- a release liner made of a low-adhesion material such as polypropylene can be used.
- the release treatment layer may be formed, for example, by subjecting the liner substrate to a surface treatment with a release treatment agent such as a silicone-based, long-chain alkyl-based, fluorine-based, or molybdenum sulfide.
- a release treatment agent such as a silicone-based, long-chain alkyl-based, fluorine-based, or molybdenum sulfide.
- the total thickness of the pressure-sensitive adhesive sheet disclosed herein is not particularly limited.
- the total thickness of the pressure-sensitive adhesive sheet can be, for example, about 800 ⁇ m or less, and is preferably about 500 ⁇ m or less, and preferably about 350 ⁇ m or less (eg, about 300 ⁇ m or less) from the viewpoint of reducing the thickness of the portable device.
- the technology disclosed herein may be applied to a pressure-sensitive adhesive sheet (typically a double-sided pressure-sensitive adhesive sheet) having a total thickness of about 250 ⁇ m or less (more preferably, about 200 ⁇ m or less, still more preferably about 150 ⁇ m or less, for example, about 120 ⁇ m or less).
- a pressure-sensitive adhesive sheet typically a double-sided pressure-sensitive adhesive sheet having a total thickness of about 250 ⁇ m or less (more preferably, about 200 ⁇ m or less, still more preferably about 150 ⁇ m or less, for example, about 120 ⁇ m or less).
- the lower limit of the thickness of the pressure-sensitive adhesive sheet is not particularly limited, but is preferably about 60 ⁇ m or more, and is preferably about 100 ⁇ m or more, about 150 ⁇ m or more, or about 180 ⁇ m or more from the viewpoint of impact resistance and the like. It may be about 200 ⁇ m or more (for example, about 220 ⁇ m or more).
- the pressure-sensitive adhesive sheet disclosed herein may have an impact resistance of about 0.2 J or more as measured by the method described in Examples described later.
- a pressure-sensitive adhesive sheet showing a higher energy amount can exhibit better impact resistance.
- the impact resistance is suitably about 0.3 J or more, preferably about 0.4 J or more, more preferably about 0.5 J or more, and still more preferably about 0.6 J or more (for example, about 0.1 J or more). 7J or more).
- the upper limit of the impact resistance is not particularly limited, and may be about 1.5 J or less (eg, 1.2 J or less) from the viewpoint of compatibility with other characteristics.
- the pressure-sensitive adhesive sheet disclosed herein is not particularly limited, but may have a 180 ° peel strength (low-temperature adhesive strength) at 10 ° C of about 5 N / 20 mm or more.
- the pressure-sensitive adhesive sheet having such a pressure-sensitive adhesive strength can exhibit good adhesiveness to an adherend even in a low-temperature region in addition to the deformation resistance in the Z-axis direction in a high-temperature region.
- the low-temperature adhesive strength is preferably 7 N / 20 mm or more, more preferably about 9 N / 20 mm or more, further preferably about 11 N / 20 mm or more, and even about 13 N / 20 mm or more (for example, about 14 N / 20 mm or more). Good.
- the lower limit of the low-temperature adhesive force is not particularly limited, but may be about 30 N / 20 mm or less (for example, about 20 N / 20 mm or less).
- the low-temperature adhesive strength is measured by a method described in Examples described later.
- the pressure-sensitive adhesive sheet disclosed herein is typically determined to be “Pass” in a Z-axis direction deformation resistance test (65 ° C. 90% RH) performed by a method described in Examples described later.
- the pressure-sensitive adhesive sheet disclosed herein may be determined to be “passed” in a high-temperature holding power evaluation test performed by a method described in Examples described later. A pressure-sensitive adhesive sheet that satisfies these characteristics has excellent holding power under high-temperature conditions.
- the pressure-sensitive adhesive sheet disclosed herein exhibits good deformation resistance even in severe environments such as high-temperature conditions, and also has excellent impact resistance.
- the pressure-sensitive adhesive sheet can be preferably used for fixing members in various portable devices (portable devices).
- portable devices portable devices
- it is suitable for use in fixing members (including various wirings) in portable electronic devices.
- portable electronic devices include mobile phones, smartphones, tablet computers, notebook computers, and various wearable devices (for example, a wrist wear type worn on a wrist like a wrist watch, a clip or strap, etc.).
- Modular type eyeglass type (monocular type or binocular type, including head mounted type), eyewear type including glasses, clothing type, earphone attached to shirts, socks, hats, etc. in the form of accessories, for example Earphones attached to the ears, etc.), digital cameras, digital video cameras, audio equipment (portable music players, IC recorders, etc.), calculators (calculators, etc.), portable game devices, electronic dictionaries, electronic notebooks, electronic books, on-board Information devices, portable radios, portable televisions, portable printers, portable scanners, portable modems and the like.
- portable devices other than portable electronic devices include mechanical wristwatches, pocket watches, flashlights, hand mirrors, periodic pockets, and the like.
- “portable” means that it is not enough to simply carry a portable device, and that an individual (standard adult) has a level of portability that can be relatively easily carried. Shall mean.
- the pressure-sensitive adhesive sheet disclosed herein can be used for fixing members constituting the above-described portable electronic device in the form of a bonding material processed into various shapes.
- it can be preferably used for a liquid crystal display device or a portable electronic device having an organic EL display. Since the pressure-sensitive adhesive sheet disclosed herein has excellent impact resistance, it can be preferably used for fixing members in a portable electronic device having an organic EL display, which tends to require higher impact resistance.
- an electronic device for example, a portable electronic device such as a smartphone
- a display unit such as a touch panel display (which may be a display unit of a liquid crystal display device or an organic EL display), and a large screen thereof
- the pressure-sensitive adhesive sheet disclosed herein is preferably used for fixing the elastic adherend.
- the elastic adherend can be fixed in a bent state, and the fixed state is continuously maintained even in a severe environment such as a high temperature condition. be able to.
- the elastic member housed in a limited internal space in the portable electronic device in a folded state can be accurately positioned by the adhesive sheet disclosed herein and held in a stable fixed state.
- a material arranged inside the portable electronic device as described above a material having polarity and rigidity, such as PET, PC (polycarbonate), or PI (polyimide), may be used.
- the adhesive sheet disclosed herein can adhere well to this type of material (polar and rigid resin material).
- the pressure-sensitive adhesive sheet disclosed herein can exhibit an excellent effect on a material whose adherend is made of PET.
- a form having a width of 20 mm or less (for example, 15 mm or less, and further less than 10 mm) is exemplified.
- the pressure-sensitive adhesive sheet disclosed herein can satisfactorily fix a member even when used as a bonding material in a region where the width is limited.
- the lower limit of the width of the pressure-sensitive adhesive sheet is not particularly limited, but is preferably 1 mm or more (for example, 3 mm or more) from the viewpoint of handleability of the pressure-sensitive adhesive sheet.
- a portable electronic device The display unit has a touch panel that also functions as an input unit, The members (plural forms) constituting the portable electronic device are joined via an adhesive sheet,
- the pressure-sensitive adhesive sheet has a foam base material and a pressure-sensitive adhesive layer provided on at least one surface of the foam base material,
- the pressure-sensitive adhesive layer contains an acrylic polymer as a base polymer,
- the portable electronic device wherein the pressure-sensitive adhesive layer has a storage elastic modulus G ′ (65 ° C.) at 65 ° C. of more than 30,000 Pa.
- G ′ 65 ° C.
- An adhesive sheet comprising a foam base material and an adhesive layer provided on at least one surface of the foam base material,
- the pressure-sensitive adhesive layer contains an acrylic polymer as a base polymer,
- the pressure-sensitive adhesive sheet wherein the pressure-sensitive adhesive layer has a storage modulus G ′ (65 ° C.) at 65 ° C. of greater than 30,000 Pa.
- the adhesive according to (11), wherein the monomer component constituting the acrylic polymer contains more than 50% by weight of an alkyl (meth) acrylate having an alkyl group having 1 to 6 carbon atoms at an ester terminal.
- Sheet (13) The pressure-sensitive adhesive sheet according to (11) or (12), wherein the monomer component constituting the acrylic polymer contains a carboxy group-containing monomer.
- a portable device comprising: the pressure-sensitive adhesive sheet according to any one of (11) to (28); and a part joined by the pressure-sensitive adhesive sheet.
- a pressure-sensitive adhesive composition is applied to the release surface of a 38 ⁇ m-thick PET film having one surface subjected to release treatment with a silicone-based release treatment agent, and dried at 100 ° C. for 2 minutes to form a 50 ⁇ m-thick adhesive film on the release surface. Form an agent layer.
- a laminated pressure-sensitive adhesive sample having a thickness of about 2 mm is produced.
- a sample obtained by punching the laminated pressure-sensitive adhesive sample into a disk shape having a diameter of 7.9 mm was fixed by sandwiching the sample with a parallel plate, and a viscoelasticity tester (manufactured by TA Instruments Inc., model name "ARES”) was used as follows.
- the dynamic viscoelasticity is measured under the conditions, and a storage elastic modulus at 65 ° C [Pa] and a loss elastic modulus at 65 ° C [Pa] are obtained.
- Tg peak temperature of tan ⁇
- peak intensity at tan ⁇ G ′′ / G ′
- storage elastic modulus at 25 ° C. G ′ (25 ° C.)
- G ′′ (25 ° C.) can also be determined.
- Measurement condition ⁇ Measurement mode: Shear mode ⁇ Temperature range: -70 ° C to 150 ° C -Temperature rise rate: 5 ° C / min ⁇ Measurement frequency: 1Hz
- a PET film 52 having a thickness of 125 ⁇ m is laminated and fixed so as to cover one entire surface of a PC board 50 having a length of 30 mm, a width of 10 mm and a thickness of 2 mm.
- a PET film 60 having a length of 70 mm, a width of 10 mm, and a thickness of 125 ⁇ m is prepared, and the PC board 50 and the PET film 60 are overlapped so that one end in the longitudinal direction thereof is aligned.
- the PC board 50 and the PET film 60 are fixed while protruding from the other end of the 50.
- a commercially available double-sided adhesive tape ("No.
- An adhesive sheet having both adhesive surfaces protected by two release liners is cut into a size of 3 mm in width and 10 mm in length to prepare an adhesive sheet sample 70.
- the surface of the PET film 52 laminated on the PC board 50 is placed on the upper side, one of the release liners is peeled off from the pressure-sensitive adhesive sheet sample piece 70, and the width direction of the PC plate 50 and the longitudinal direction of the pressure-sensitive adhesive sheet sample piece 70 are aligned.
- the pressure-sensitive adhesive sheet sample 70 is placed on the upper surface of the PET film 52 laminated and fixed on the PC board 50 so that both ends in the width direction of the pressure-sensitive adhesive sheet sample 70 are located on lines of 7 mm and 10 mm from the other end.
- the fixing is performed by reciprocating the upper surface of the pressure-sensitive adhesive sheet sample 70, which is protected by the other release liner, with a 2 kg roller once.
- the other release liner of the pressure-sensitive adhesive sheet sample 70 attached to the PET film 52 was peeled off, and as shown in FIG.
- the protruding portion (length 40 mm) of the PET film 60 fixed to the PC plate 50 is folded back toward the PC plate 50 so that the adhesive sheet sample 70 and the other end (free end) of the PET film 60 are aligned.
- the other end of the folded PET film 60 is pressed onto the upper surface of the PET film 52 on the PC board 50 through the adhesive sheet sample piece 70 by pressure bonding under a condition of 0.5 MPa and 0.5 seconds using a press machine. Fix it. After the pressure bonding, it is left for 72 hours in an environment of 65 ° C. and 90% RH, and whether or not the PET film 60 peels from the pressure-sensitive adhesive sheet sample 70 is evaluated as the Z-axis direction deformation resistance (65 ° C. 90% RH). A case where the adhesive state between the pressure-sensitive adhesive sheet sample 70 and the PET film 60 is maintained is judged as “pass”, and a case where the PET film 60 is peeled off as shown in FIG.
- this evaluation method unlike the conventional repulsion resistance evaluation, it is necessary to evaluate the deformation resistance under a high-temperature and high-humidity condition with respect to a peeling load substantially only in the thickness direction (Z-axis direction) of the pressure-sensitive adhesive sheet. It is possible to evaluate the sustained deformation resistance by observing over time.
- a pressure-sensitive adhesive sheet (double-sided pressure-sensitive adhesive sheet) having a pressure-sensitive adhesive surface protected by a release liner is punched into a frame having a width of 2 mm and an outer diameter of 24.5 mm to obtain a window-frame-shaped pressure-sensitive adhesive sheet.
- a stainless steel plate having a thickness of 2 mm and an outer shape of 50 mm ⁇ 50 mm with a hole in the center and a square PET plate (outer shape 25 mm square, 2 mm thick) are prepared, and a release liner is placed between the two.
- the stainless steel plate and the PET plate are fixed with the window frame-shaped pressure-sensitive adhesive sheet by disposing the removed window frame-shaped pressure-sensitive adhesive sheet and applying pressure so that pressure is applied uniformly at 62 N for 10 seconds. This is allowed to stand in a 50 ° C. environment for 2 hours, taken out, and then returned to 23 ° C. This is used as an evaluation sample.
- a cylindrical measuring table having a length of 50 mm, an outer diameter of 49 mm, and an inner diameter of 43 mm is set on a pedestal of a Dupont impact tester (manufactured by Toyo Seiki Seisaku-sho, Ltd.). An evaluation sample is placed on the sample with the square PET plate facing down.
- the upper stainless steel plate is supported by the measuring table, and the lower PET plate enters the hollow portion in the measuring table in a state where the lower PET plate is bonded to the stainless steel plate by the window frame-shaped adhesive sheet.
- shots A stainless steel hammer with a tip radius of 3.1 mm (shot type) is placed on a PET plate below the evaluation sample, and the weight is set at 23 ° C. and 50% RH under the following conditions (weight and drop height). Is dropped on the shooting core. The weight and the weight drop height start from the condition with the smallest energy amount, and are changed to increase the energy amount. The weight drop height is increased at 50 mm intervals.
- the measured energy amount (the energy amount obtained from the weight weight and the weight drop height) is not measured, and the conditions (weight weight x weight drop height) where the energy amounts do not overlap are set, A weight drop test shall be performed.
- Weight weight (weight drop height) 100g 50mm-500mm 150g 350mm-500mm 200g 400mm-500mm 300g 350mm-500mm
- the energy amount (J) under the condition immediately before the separation between the stainless steel plate and the PET plate occurs is calculated from the weight (load) and the drop height, and this is recorded as a measured value of impact resistance. When the measured value is 0.2 J or more, it can be said that the impact resistance is excellent.
- the release liner that covers one adhesive surface of the double-sided adhesive sheet is peeled off, and is adhered to a 50 ⁇ m-thick PET film for backing.
- the backed adhesive sheet is cut into a size of 10 mm in width and 100 mm in length to prepare a measurement sample.
- the release liner covering the other adhesive surface of the measurement sample is peeled off, and the other adhesive surface is pressure-bonded to a bakelite plate as an adherend by reciprocating a 2 kg roller once. Thereafter, the measurement sample is cut so that the bonding length to the bakelite plate is 20 mm (therefore, the bonding area is 200 mm 2 : 10 mm width ⁇ 20 mm length).
- tensile / compression tester “tensile / compression tester, TG-1kN” manufactured by Minebea or its equivalent is used. In the case of a single-sided pressure-sensitive adhesive sheet, backing of the PET film is unnecessary.
- Example 1 A reaction vessel equipped with a stirrer, a thermometer, a nitrogen gas inlet tube, a reflux condenser and a dropping funnel was charged with 95 parts of BA and 5 parts of AA as a monomer component and 233 parts of ethyl acetate as a polymerization solvent, and nitrogen gas was introduced. For 2 hours. After removing oxygen in the polymerization system in this manner, 0.2 parts of AIBN was added as a polymerization initiator, and solution polymerization was performed at 60 ° C. for 8 hours to obtain a solution of an acrylic polymer A1.
- the Mw of the acrylic polymer A1 was about 60 ⁇ 10 4 to 70 ⁇ 10 4 , and the Mw / Mn was about 4 to 5.
- a tackifier resin B1 product name “YS Polystar S145”, manufactured by Yashara Chemical Co., Ltd., terpene phenol resin, softening point 145 ° C., hydroxyl value 70 to 110 mg KOH / g
- 30 parts of an isocyanate-based crosslinking agent (trade name “Coronate L”, 75% ethyl acetate solution of trimethylolpropane / tolylene diisocyanate trimer adduct, manufactured by Tosoh Corporation) in 2 parts (in terms of solid content)
- An epoxy-based crosslinking agent (trade name “TETRAD-C”, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, manufactured by Mitsubishi Gas Chemical Co., Ltd.) is mixed with 0.01 part (in terms of solid content).
- the mixture was stirred and mixed to prepare a pressure-sensitive adhesive composition according to this example.
- Two commercially available release liners (trade name "SLB-80W3D", manufactured by Sumika Kagaku Co., Ltd.) were prepared, and the adhesive composition was applied to one surface (release surface) of each of the release liners, and the thickness after drying was measured.
- the adhesive layer was formed on each of the release surfaces of the two release liners by applying the solution so as to have a thickness of 40 ⁇ m and drying at 100 ° C. for 2 minutes.
- These pressure-sensitive adhesive layers were coated with a polyethylene foam sheet (thickness 200 ⁇ m, density 0.43 g / cm 3 , 10% compressive strength (C 10 ) 330 kPa, 25% compressive strength (C 25 ) 942 kPa, 30% compressive strength (C 30 ) 1235 kPa, average cell diameter 55 ⁇ m).
- the release liner was left on the pressure-sensitive adhesive layer as it was and used for protecting the surface (pressure-sensitive surface) of the pressure-sensitive adhesive layer.
- the obtained structure was passed through a laminator (0.3 MPa, speed 0.5 m / min) at 80 ° C. once, and then cured in an oven at 50 ° C. for 1 day.
- the pressure-sensitive adhesive sheet according to this example double-sided pressure-sensitive adhesive sheet with a foam base material
- Example 6> The monomer composition was changed to 100 parts of BA, 3 parts of VAc, 5 parts of AA and 0.1 part of HEA, and the same procedure as in Example 1 was repeated except that toluene was used as a polymerization solvent, to obtain an acrylic resin having a Mw of 50 ⁇ 10 4 to 60 ⁇ 10 4 .
- a solution of the system polymer A2 was obtained.
- 35 parts of a tackifier resin and 2 parts of an isocyanate crosslinking agent (trade name “Coronate L”, manufactured by Tosoh Corporation) (in terms of solid content) were added to 100 parts of the acrylic polymer.
- tackifier resin examples include tackifier resin B2 (product name “Sumilite Resin PR-12603N”, manufactured by Sumitomo Bakelite Co., Ltd., terpene-modified phenolic resin, softening point 130-140 ° C., hydroxyl value 1-20 mgKOH / g).
- tackifying resin B3 product name “Haritack SE10”, manufactured by Harima Chemicals, hydrogenated rosin glycerin ester, softening point 75 to 85 ° C., hydroxyl value 25 to 40 mg KOH / g
- tackifying resin B4 product 10 parts of “Haritac PCJ” (manufactured by Harima Chemicals, Inc., polymerized rosin ester, softening point 118-128 ° C.) were used.
- Example 7 A solution of an acrylic polymer A3 having a Mw of 44 ⁇ 10 4 was obtained basically in the same manner as in Example 6, except that the monomer composition was changed to 70 parts of BA, 30 parts of EHA, 3 parts of AA, and 0.05 part of 4-HBA.
- a tackifier resin B5 product name “Pencel D-125”, manufactured by Arakawa Chemical Industry Co., Ltd., rosin ester resin, softening point 120 to 130 ° C.
- an isocyanate-based crosslinking agent (trade name “Coronate L”, manufactured by Tosoh Corporation) (3 parts in terms of solid content) were blended and mixed by stirring to prepare an acrylic pressure-sensitive adhesive composition according to this example.
- Example 8 Using the pressure-sensitive adhesive composition prepared in Example 1, a 50- ⁇ m-thick PET film was used as a substrate instead of the foam substrate, and a 50- ⁇ m-thick pressure-sensitive adhesive layer was formed on both sides of the PET film substrate. A double-sided PSA sheet with a PET film substrate according to the example was obtained.
- the pressure-sensitive adhesive sheets according to Examples 1 to 5 each including a pressure-sensitive adhesive layer having a storage elastic modulus of 65 ° C. greater than 30,000 and a foam base material were resistant to deformation in the Z-axis direction under high temperature and high humidity conditions.
- the evaluation result was passed and the impact resistance was excellent.
- the pressure-sensitive adhesive sheets of Examples 1 to 5 also passed the high-temperature holding power test at 80 ° C. and were excellent in the low-temperature adhesion at 10 ° C.
- Examples 6 and 7 in which the storage elastic modulus at 65 ° C. was 30,000 or less the above-described evaluation results of the deformation resistance in the Z-axis direction failed.
- Example 8 using the PET film substrate instead of the foam substrate, the result of the impact resistance test was inferior to Examples 1 to 5. From the above results, the pressure-sensitive adhesive sheet provided with a pressure-sensitive adhesive layer having a storage elastic modulus of 65 ° C. greater than 30,000 and a foam base material exhibits good deformation resistance even when used in a severe environment. It can be seen that they have excellent impact resistance.
- Adhesive sheet 10 Foam base material 10A 1st surface 10B 2nd surface 21 1st adhesive layer 22 2nd adhesive layer 21A 1st adhesive surface 22A 2nd adhesive surface 31, 32 Release liner
Abstract
Description
ここに開示される粘着シート(テープ状等の長尺状の形態であり得る。)は、発泡体基材と、該発泡体基材の少なくとも一方の面に設けられた粘着剤層と、を備える。かかる粘着シートは、発泡体基材の一方の面にのみ粘着剤層を有し、該一方の面のみが粘着性表面(粘着面)となっている片面粘着シートの形態であってもよい。このような片面粘着シートは、例えば、粘着剤層を有しない側の面を粘着以外の手法(例えば、接着剤を用いる方法、熱融着させる方法等)で被着体に固定することにより、部品の接合や固定に用いられ得る。ここに開示される粘着シートは、典型的には、発泡体基材の両面に粘着剤層を有する両面粘着シート(発泡体基材付き両面粘着シート)の形態で好ましく実施される。このような両面粘着シートは、例えば、部品の接合操作の簡便性や接合品質の安定性等の観点から有利である。なお、ここでいう粘着シートの概念には、粘着テープ、粘着ラベル、粘着フィルム等と称されるものが包含され得る。また、ここに開示される粘着シートは、ロール状であってもよく、枚葉状であってもよい。あるいは、さらに種々の形状に加工された形態の粘着シートであってもよい。
(65℃貯蔵弾性率)
ここに開示される粘着剤層(第1粘着剤層および第2粘着剤層を備える場合は、その両方。特に断りがないかぎり以下同じ。)は、65℃における貯蔵弾性率G´(65℃)が30000Paよりも大きいことによって特徴づけられる。上記G´(65℃)を有する粘着剤を用いることで、高温条件などの過酷な環境においても良好な耐変形性を発揮する。上記G´(65℃)は、好ましくは40000Pa超、より好ましくは50000Pa超、さらに好ましくは55000Pa以上である。所定以上のG´(65℃)を有する粘着剤層を備えるものは、高温保持力にも優れる傾向がある。また、上記G´(65℃)の上限は特定の範囲に限定されず、1.0MPa以下とすることが適当であり、初期接着性(例えば低温接着力)と耐変形性との両立の観点から、好ましくは凡そ500000Pa以下であり、凡そ200000Pa以下であってもよく、凡そ100000Pa以下でもよく、凡そ80000Pa以下でもよい。ここに開示される粘着シートが両面粘着シートである態様においては、第1粘着剤層および第2粘着剤層の貯蔵弾性率G´(65℃)は、同じであってもよく異なっていてもよい。上記貯蔵弾性率G´(65℃)は、粘着剤組成(例えばベースポリマーのモノマー組成や分子量、粘着付与樹脂の軟化点、架橋剤種、それら成分の含有割合)や製造方法(ポリマーの重合条件等)によって調節することができる。65℃貯蔵弾性率は、後述の実施例に記載の方法で測定することができる。
また、特に限定されるものではないが、ここに開示される粘着剤層は、65℃における損失弾性率G″(65℃)が凡そ500000Pa以下であることが適当である。加工性や取扱い性の観点から、上記G″(65℃)は、好ましくは凡そ100000Pa以下であり、凡そ50000Pa以下であってもよく、凡そ30000Pa以下でもよい。また、上記G″(65℃)は、凡そ1000Pa以上であることが適当であり、被着体表面への濡れ性、ひいては初期接着性等の観点から、好ましくは凡そ5000Pa以上であり、凡そ10000Pa以上でもよい。所定以上のG″(65℃)を有する粘着剤層を備えるものは、耐衝撃性にも優れる傾向がある。ここに開示される粘着シートが両面粘着シートである態様においては、第1粘着剤層および第2粘着剤層の損失弾性率G″(65℃)は、同じであってもよく異なっていてもよい。上記損失弾性率G″(65℃)は、粘着剤組成(例えばベースポリマーのモノマー組成や分子量、粘着付与樹脂の軟化点、架橋剤種、それら成分の含有割合)や製造方法(ポリマーの重合条件等)によって調節することができる。65℃損失弾性率は、後述の実施例に記載の方法で測定することができる。
ここに開示される粘着剤層の25℃貯蔵弾性率は特に限定されず、例えば凡そ1MPa以下であり得る。粘着剤層の25℃貯蔵弾性率は凡そ0.5MPa以下であってよく、好ましくは凡そ0.3MPa以下(例えば凡そ0.25MPa以下)である。粘着剤層の25℃貯蔵弾性率が低くなると、常温域において粘着剤層の柔軟性が高くなることから、被着体表面に粘着面を密接させやすい。また、貯蔵弾性率が所定値以下に制限された粘着剤によると、良好な耐衝撃性が得られやすい。また、上記25℃貯蔵弾性率は凡そ0.01MPa以上であり得る。所定値以上の25℃貯蔵弾性率を示す粘着剤によると、常温域において適度な凝集性を有するので接着強度を高めやすい。そのような観点から、上記25℃貯蔵弾性率は、凡そ0.02MPa以上であることが適当であり、好ましくは0.05MPa以上、より好ましくは凡そ0.1MPa以上、さらに好ましくは凡そ0.14MPa以上(例えば0.15MPa以上)、特に好ましくは凡そ0.18MPa以上(例えば凡そ0.2MPa以上)である。粘着剤層の25℃貯蔵弾性率は、粘着剤層の組成や製造方法等により調節することができる。25℃貯蔵弾性率は、後述の実施例に記載の方法で測定することができる。
特に限定されるものではないが、ここに開示される粘着シートを構成する粘着剤層のTgは、凡そ25℃以下に制御されていることが、被着体との密着性および耐衝撃性の観点から適当である。粘着剤層のTgは、好ましくは凡そ20℃以下(典型的には凡そ15℃以下、例えば凡そ10℃以下)である。また、粘着剤層のTgは、耐衝撃性等の観点から、凡そ-25℃以上であることが適当であり、好ましくは凡そ-15℃以上、より好ましくは凡そ-10℃以上(例えば凡そ-5℃以上)であり、凡そ0℃以上(例えば凡そ5℃以上)であってもよい。ここに開示される技術によると、上記Tgを有することで、所望の粘着特性(例えば接着力や耐衝撃性)を好ましく実現することができる。粘着付与樹脂種(例えば高水酸基価樹脂)の選択で要求特性を満足する態様においては、上記範囲のTgとすることで、粘着剤の粘弾性特性および粘着付与樹脂の化学特性に基づく作用が好ましく発揮され得る。なお、本明細書における粘着剤層のTgとは、動的粘弾性測定におけるtanδのピーク温度から求められるガラス転移温度をいう。粘着剤層のTgは、粘着剤組成(例えばベースポリマーのTg、粘着付与樹脂の軟化点、架橋剤種、それら成分の含有割合)や製造方法(ポリマーの重合条件等)によって調節することができる。粘着剤層のTgは、後述の実施例に記載の方法で測定することができる。
粘着剤層のtanδのピークにおける値(ピーク強度)は、典型的には1.0以上であり、好ましくは凡そ1.5以上、より好ましくは凡そ1.8以上、さらに好ましくは凡そ2.0以上である。比較的低温域(典型的には-25℃~25℃の範囲)にtanδのピークを有する粘着剤において、所定値以上のピーク強度を有するものは、耐衝撃性に優れたものとなり得る。また、上記tanδのピーク強度は、凡そ3.0以下が適当であり、好ましくは凡そ2.5以下であり、凡そ2.2未満(例えば2.0未満)であってもよい。粘着剤層のtanδのピーク強度は、粘着剤組成(例えばベースポリマーのTg、粘着付与樹脂の軟化点、架橋剤種、それら成分の含有割合)や製造方法(ポリマーの重合条件等)によって調節することができる。粘着剤層のtanδのピーク強度は、後述の実施例に記載の方法で測定することができる。
ここに開示される粘着剤層を構成する粘着剤は、アクリル系ポリマーをベースポリマーとして含むアクリル系粘着剤である。なお、ベースポリマーとは、粘着剤層に含まれるゴム状ポリマー(室温付近の温度域においてゴム弾性を示すポリマー)の主成分をいう。また、この明細書において「主成分」とは、特記しない場合、50重量%を超えて含まれる成分を指す。また、本明細書において「アクリル系粘着剤」とは、アクリル系ポリマーをベースポリマー(ポリマー成分のなかの主成分、すなわち50重量%以上を占める成分)とする粘着剤を指す。また、「アクリル系ポリマー」とは、該ポリマーを構成するモノマー単位として、1分子中に少なくとも1つの(メタ)アクリロイル基を有するモノマーに由来するモノマー単位を含む重合物をいう。以下、1分子中に少なくとも1つの(メタ)アクリロイル基を有するモノマーを「アクリル系モノマー」ともいう。したがって、この明細書におけるアクリル系ポリマーは、アクリル系モノマーに由来するモノマー単位を含むポリマーとして定義される。なお、この明細書において「(メタ)アクリロイル」とは、アクリロイルおよびメタクリロイルを包括的に指す意味である。同様に、「(メタ)アクリレート」とはアクリレートおよびメタクリレートを、「(メタ)アクリル」とはアクリルおよびメタクリルを、それぞれ包括的に指す意味である。
上記アクリル系ポリマーとしては、例えば、アルキル(メタ)アクリレートを主モノマーとして含み、該主モノマーと共重合性を有する副モノマーをさらに含み得るモノマー原料の重合物が好ましい。ここで主モノマーとは、上記モノマー原料におけるモノマー組成の50重量%超を占める成分をいう。
CH2=C(R1)COOR2 (1)
ここで、上記式(1)中のR1は水素原子またはメチル基である。また、R2は炭素原子数1~20の鎖状アルキル基である。以下、このような炭素原子数の範囲を「C1-20」と表すことがある。粘着剤の貯蔵弾性率等の観点から、R2がC1-14(例えばC2-10、あるいはC4-8)の鎖状アルキル基であるアルキル(メタ)アクリレートを主モノマーとすることが適当である。粘着特性の観点から、R1が水素原子であってR2がC4-8の鎖状アルキル基であるアルキルアクリレート(以下、単にC4-8アルキルアクリレートともいう。)を主モノマーとすることが好ましい。
1/Tg=Σ(Wi/Tgi)
なお、上記Foxの式において、Tgは共重合体のガラス転移温度(単位:K)、Wiは該共重合体におけるモノマーiの重量分率(重量基準の共重合割合)、Tgiはモノマーiのホモポリマーのガラス転移温度(単位:K)を表す。
2-エチルヘキシルアクリレート -70℃
n-ブチルアクリレート -55℃
エチルアクリレート -22℃
メチルアクリレート 8℃
メチルメタクリレート 105℃
2-ヒドロキシエチルアクリレート -15℃
4-ヒドロキシブチルアクリレート -40℃
酢酸ビニル 32℃
スチレン 100℃
アクリル酸 106℃
メタクリル酸 228℃
具体的には、温度計、攪拌機、窒素導入管および還流冷却管を備えた反応器に、モノマー100重量部、2,2’-アゾビスイソブチロニトリル0.2重量部および重合溶媒として酢酸エチル200重量部を投入し、窒素ガスを流通させながら1時間攪拌する。このようにして重合系内の酸素を除去した後、63℃に昇温し10時間反応させる。次いで、室温まで冷却し、固形分濃度33重量%のホモポリマー溶液を得る。次いで、このホモポリマー溶液を剥離ライナー上に流延塗布し、乾燥して厚さ約2mmの試験サンプル(シート状のホモポリマー)を作製する。この試験サンプルを直径7.9mmの円盤状に打ち抜き、パラレルプレートで挟み込み、粘弾性試験機(ティー・エイ・インスツルメント・ジャパン社製、機種名「ARES」)を用いて周波数1Hzのせん断歪みを与えながら、温度領域-70℃~150℃、5℃/分の昇温速度でせん断モードにより粘弾性を測定し、tanδ(損失正接)のピークトップ温度をホモポリマーのTgとする。
ここに開示される粘着剤層は、上記ベースポリマーに加えて粘着付与樹脂を含むことが好ましい。粘着付与樹脂としては、ロジン系樹脂、テルペン樹脂、変性テルペン樹脂、フェノール系樹脂、スチレン系樹脂、炭化水素系粘着付与樹脂、エポキシ系粘着付与樹脂、ポリアミド系粘着付与樹脂、エラストマー系粘着付与樹脂、ケトン系樹脂等の、公知の各種粘着付与樹脂から選択される1種または2種以上を用いることができる。なかでも、フェノール系粘着付与樹脂が好ましい。
テルペンフェノール樹脂とは、テルペン残基およびフェノール残基を含むポリマーを指し、テルペン類とフェノール化合物との共重合体(テルペン-フェノール共重合体樹脂)と、テルペン類の単独重合体または共重合体をフェノール変性したもの(フェノール変性テルペン樹脂)との双方を包含する概念である。このようなテルペンフェノール樹脂を構成するテルペン類の好適例としては、α-ピネン、β-ピネン、リモネン(d体、l体およびd/l体(ジペンテン)を包含する。)等のモノテルペン類が挙げられる。水素添加テルペンフェノール樹脂とは、このようなテルペンフェノール樹脂を水素化した構造を有する水素添加テルペンフェノール樹脂をいう。水添テルペンフェノール樹脂と称されることもある。
アルキルフェノール樹脂は、アルキルフェノールとホルムアルデヒドから得られる樹脂(油性フェノール樹脂)である。アルキルフェノール樹脂の例としては、ノボラックタイプおよびレゾールタイプのものが挙げられる。
ロジンフェノール樹脂は、典型的には、ロジン類または上記の各種ロジン誘導体(ロジンエステル類、不飽和脂肪酸変性ロジン類および不飽和脂肪酸変性ロジンエステル類を包含する。)のフェノール変性物である。ロジンフェノール樹脂の例には、ロジン類または上記の各種ロジン誘導体にフェノールを酸触媒で付加させ熱重合する方法等により得られるロジンフェノール樹脂が含まれる。
ロジン類の例には、ガムロジン、ウッドロジン、トール油ロジン等の未変性ロジン(生ロジン);これらの未変性ロジンを水素添加、不均化、重合等により変性した変性ロジン(水素添加ロジン、不均化ロジン、重合ロジン、その他の化学的に修飾されたロジン等);が含まれる。
ロジン誘導体樹脂としては、例えば、未変性ロジンとアルコール類とのエステルである未変性ロジンエステル、変性ロジンとアルコール類とのエステルである変性ロジンエステル等のロジンエステル類;例えば、ロジン類を不飽和脂肪酸で変性した不飽和脂肪酸変性ロジン類;例えば、ロジンエステル類を不飽和脂肪酸で変性した不飽和脂肪酸変性ロジンエステル類;例えば、ロジン類または上記の各種ロジン誘導体(ロジンエステル類、不飽和脂肪酸変性ロジン類および不飽和脂肪酸変性ロジンエステル類を包含する。)のカルボキシ基を還元処理したロジンアルコール類;例えば、ロジン類または上記の各種ロジン誘導体の金属塩;等が挙げられる。
変性テルペン樹脂の例としては、上記テルペン樹脂を変性したものが挙げられる。具体的には、スチレン変性テルペン樹脂、水素添加テルペン樹脂等が例示される。ただし、後述するテルペンフェノール樹脂または水素添加テルペンフェノール樹脂に該当するものは、変性テルペン樹脂ではなくフェノール系樹脂に属するものとして扱う。
[水酸基価の測定方法]
1.試薬
(1)アセチル化試薬としては、無水酢酸約12.5g(約11.8mL)を取り、これにピリジンを加えて全量を50mLにし、充分に攪拌したものを使用する。または、無水酢酸約25g(約23.5mL)を取り、これにピリジンを加えて全量を100mLにし、充分に攪拌したものを使用する。
(2)測定試薬としては、0.5mol/L水酸化カリウムエタノール溶液を使用する。
(3)その他、トルエン、ピリジン、エタノールおよび蒸留水を準備する。
2.操作
(1)平底フラスコに試料約2gを精秤採取し、アセチル化試薬5mLおよびピリジン10mLを加え、空気冷却管を装着する。
(2)上記フラスコを100℃の浴中で70分間加熱した後、放冷し、冷却管の上部から溶剤としてトルエン35mLを加えて攪拌した後、蒸留水1mLを加えて攪拌することにより無水酢酸を分解する。分解を完全にするため再度浴中で10分間加熱し、放冷する。
(3)エタノール5mLで冷却管を洗い、取り外す。次いで、溶剤としてピリジン50mLを加えて攪拌する。
(4)0.5mol/L水酸化カリウムエタノール溶液を、ホールピペットを用いて25mL加える。
(5)0.5mol/L水酸化カリウムエタノール溶液で電位差滴定を行う。得られた滴定曲線の変曲点を終点とする。
(6)空試験は、試料を入れないで上記(1)~(5)を行う。
3.計算
以下の式により水酸基価を算出する。
水酸基価(mgKOH/g)=[(B-C)×f×28.05]/S+D
ここで、
B: 空試験に用いた0.5mol/L水酸化カリウムエタノール溶液の量(mL)、
C: 試料に用いた0.5mol/L水酸化カリウムエタノール溶液の量(mL)、
f: 0.5mol/L水酸化カリウムエタノール溶液のファクター、
S: 試料の重量(g)、
D: 酸価、
28.05: 水酸化カリウムの分子量56.11の1/2、
である。
ここに開示される粘着剤組成物(ひいては粘着剤層)には、接着力向上等の観点から、(メタ)アクリル系オリゴマーを含有させることができる。(メタ)アクリル系オリゴマーとしては、上記モノマー成分の組成に対応する共重合体のTg(典型的には、粘着剤組成物から形成される粘着剤に含まれるアクリル系ポリマーのTgに概ね対応する。)よりもTgが高い重合体を用いることが好ましい。(メタ)アクリル系オリゴマーを含有させることにより、粘着剤の接着力を向上させ得る。
粘着剤を形成するために用いられる粘着剤組成物は、架橋剤を含むことが好ましい。粘着剤組成物に架橋剤を含ませることによって、粘着剤に架橋構造が導入される。架橋剤の種類は特に制限されず、例えば、イソシアネート系架橋剤、エポキシ系架橋剤、オキサゾリン系架橋剤、アジリジン系架橋剤、メラミン系架橋剤、過酸化物系架橋剤、尿素系架橋剤、金属アルコキシド系架橋剤、金属キレート系架橋剤、金属塩系架橋剤、カルボジイミド系架橋剤、アミン系架橋剤等から適宜選択して用いることができる。架橋剤は、1種を単独で、または2種以上を組み合わせて用いることができる。被着体との密着性や耐衝撃性の観点からは、イソシアネート系架橋剤が好ましく、接着状態の保持性能(層形状保持を含む。)等の観点からはエポキシ系架橋剤が好ましい。ここに開示される技術によると、エポキシ系架橋剤を用いることなく、あるいはその使用量を低減しつつ、より高性能な粘着シートを提供することができる。例えば、イソシアネート系架橋剤を主架橋剤成分として用いて、被着体との密着性を高めたり、耐衝撃性を改善することができる。イソシアネート系架橋剤の使用は、例えば、PET等のポリエステル樹脂製の被着体に対する接着力改善の点で有利である。
脂肪族ポリイソシアネート類の具体例としては、1,2-エチレンジイソシアネート;1,2-テトラメチレンジイソシアネート、1,3-テトラメチレンジイソシアネート、1,4-テトラメチレンジイソシアネート等のテトラメチレンジイソシアネート;1,2-ヘキサメチレンジイソシアネート、1,3-ヘキサメチレンジイソシアネート、1,4-ヘキサメチレンジイソシアネート、1,5-ヘキサメチレンジイソシアネート、1,6-ヘキサメチレンジイソシアネート、2,5-ヘキサメチレンジイソシアネート等のヘキサメチレンジイソシアネート;2-メチル-1,5-ペンタンジイソシアネート、3-メチル-1,5-ペンタンジイソシアネート、リジンジイソシアネート、等が挙げられる。
粘着剤組成物には、上述した各成分以外に、必要に応じてレベリング剤、架橋助剤、可塑剤、軟化剤、帯電防止剤、老化防止剤、紫外線吸収剤、酸化防止剤、光安定剤等の、粘着剤の分野において一般的な各種の添加剤が含まれていてもよい。このような各種添加剤については、従来公知のものを常法により使用することができ、特に本発明を特徴づけるものではないので、詳細な説明は省略する。
架橋反応の促進、製造効率向上等の観点から、粘着剤組成物の乾燥は加熱下で行うことが好ましい。乾燥温度は、例えば40~150℃程度とすることができ、60~130℃程度とすることが好ましい。粘着剤組成物を乾燥させた後、さらに、粘着剤層内における成分移行の調整、架橋反応の進行、粘着剤層内に存在し得る歪の緩和等を目的としてエージングを行ってもよい。
粘着剤層の厚さは特に制限されない。粘着シートが過度に厚くなることを避ける観点から、粘着剤層の厚さは、凡そ100μm以下が適当であり、好ましくは凡そ70μm以下、より好ましくは凡そ60μm以下、さらに好ましくは凡そ50μm以下である。粘着剤層の厚さの下限は特に制限されないが、被着体に対する密着性の観点からは、凡そ3μm以上とすることが有利であり、好ましくは凡そ10μm以上、より好ましくは凡そ20μm以上(例えば凡そ30μm以上)である。ここに開示される粘着シートは、両面粘着シートとして構成する場合には、上記厚さの粘着剤層を基材の両面に有する粘着シートであり得る。また、基材の各面に第1粘着剤層と第2粘着剤層とをそれぞれ有する基材付き両面粘着シートにおいては、第1粘着剤層と第2粘着剤層とは同一の厚さであってもよく、相互に異なる厚さであってもよい。
特に限定するものではないが、ここに開示される粘着剤層(第1粘着剤層および第2粘着剤層を備える場合は各粘着剤層)のゲル分率は、重量基準で、例えば20%以上とすることができ、30%以上とすることが適当であり、35%以上が好ましい。粘着剤層のゲル分率を適度な範囲で高くすることにより、Z軸方向の持続的な荷重に対する耐変形性が得られやすくなる傾向にある。ここに開示される技術では、ゲル分率が40%以上の粘着剤層とすることがより好ましい。上記ゲル分率は、45%以上であってもよく、50%以上でもよく、例えば55%以上でもよい。一方、初期接着性等の観点から、粘着剤層のゲル分率は、90%以下が好ましく、80%以下がより好ましく、70%以下(例えば65%以下)がさらに好ましく、60%以下であってもよく、50%以下でもよい。ここに開示される粘着シートが基材付き両面粘着シートである場合、第1粘着剤層および第2粘着剤層のゲル分率は同じであってもよく異なっていてもよい。
ここに開示される粘着シートは発泡体基材を備える。具体的には、上記粘着シートは、発泡体基材の少なくとも一方の面に粘着剤層を有する粘着シートとして構成されている。ここに開示される技術において、発泡体基材とは、気泡(気泡構造)を有する部分を備えた基材であって、典型的には、層状の発泡体(発泡体層)を少なくとも1層含む基材をいう。上記発泡体基材は、1層または2層以上の発泡体層により構成された基材であり得る。上記発泡体基材は、例えば、1層または2層以上の発泡体層のみにより実質的に構成された基材であり得る。特に限定するものではないが、ここに開示される技術における発泡体基材の一好適例として、単層(1層)の発泡体層からなる発泡体基材が挙げられる。発泡体基材を用いることで、基材レスや樹脂フィルム基材を用いた構成と比べて優れた耐衝撃性が得られる。
アスペクト比(MD/CD)=MD平均気泡径/CD平均気泡径
MD平均気泡径(μm)=60(mm)×103/(気泡数(個)×拡大倍率)
CD平均気泡径(μm)=60(mm)×103/(気泡数(個)×拡大倍率)
発泡体基材の任意の圧縮率における圧縮強度は、JIS K 6767に準拠して測定される。具体的な測定手順としては、上記一対の平板の中央部に上記測定試料をセットし、上記平板の間隔を狭めることで連続的に任意の圧縮率まで圧縮し、そこで平板を停止させて10秒経過後の荷重を測定する。発泡体基材の圧縮強度は、例えば、発泡体基材を構成する材料の架橋度や密度、気泡のサイズや形状等により制御することができる。
上記プラスチック発泡体を架橋させる方法としては、例えば、有機過酸化物などを用いる化学架橋法、または電離性放射線を照射する電離性放射線架橋法などが挙げられ、これらの方法は併用され得る。上記電離性放射線としては、電子線、α線、β線、γ線などが例示される。電離性放射線の線量は特に限定されず、発泡体基材の目標物性(例えば架橋度)等を考慮して適切な照射線量に設定することができる。
ここに開示される技術において、粘着剤層の形成、粘着シートの作製、使用前の粘着シートの保存、流通、形状加工等の際に、剥離ライナーを用いることができる。剥離ライナーとしては、特に限定されず、例えば、樹脂フィルムや紙等のライナー基材の表面に剥離処理層を有する剥離ライナーや、フッ素系ポリマー(ポリテトラフルオロエチレン等)やポリオレフィン系樹脂(ポリエチレン、ポリプロピレン等)の低接着性材料からなる剥離ライナー等を用いることができる。上記剥離処理層は、例えば、シリコーン系、長鎖アルキル系、フッ素系、硫化モリブデン等の剥離処理剤により上記ライナー基材を表面処理して形成されたものであり得る。
ここに開示される粘着シート(粘着剤層を含み、基材層をさらに含み得るが、剥離ライナーは含まない。)の総厚さは特に限定されない。粘着シートの総厚さは、例えば凡そ800μm以下とすることができ、携帯機器の薄型化の観点から、凡そ500μm以下が適当であり、凡そ350μm以下(例えば凡そ300μm以下)が好ましい。ここに開示される技術は、総厚さが凡そ250μm以下(より好ましくは凡そ200μm以下、さらに好ましくは凡そ150μm以下、例えば凡そ120μm以下)の粘着シート(典型的には両面粘着シート)の形態でも実施され得る。粘着シートの厚さの下限は特に限定されないが、凡そ60μm以上が適当であり、耐衝撃性等の観点から、好ましくは凡そ100μm以上であり、凡そ150μm以上であってもよく、凡そ180μm以上でもよく、凡そ200μm以上(例えば凡そ220μm以上)でもよい。
ここに開示される粘着シートは、後述の実施例に記載の方法で測定される耐衝撃性が凡そ0.2J以上であり得る。より高いエネルギー量を示す粘着シートは、より優れた耐衝撃性を発揮し得る。そのような観点から、上記耐衝撃性は凡そ0.3J以上が適当であり、好ましくは凡そ0.4J以上、より好ましくは凡そ0.5J以上、さらに好ましくは凡そ0.6J以上(例えば0.7J以上)である。上記耐衝撃性の上限は特に限定されず、他の特性との両立等の観点から、1.5J以下(例えば1.2J以下)程度であり得る。
ここに開示される粘着シートは、高温条件などの過酷な環境においても良好な耐変形性を発揮し、また耐衝撃性にも優れる。このような特徴を活かして、上記粘着シートは、各種の携帯機器(ポータブル機器)において部材の固定に好ましく利用され得る。例えば、携帯電子機器における部材(各種配線を包含する。)の固定用途に好適である。上記携帯電子機器の非限定的な例には、携帯電話、スマートフォン、タブレット型パソコン、ノート型パソコン、各種ウェアラブル機器(例えば、腕時計のように手首に装着するリストウェア型、クリップやストラップ等で体の一部に装着するモジュラー型、メガネ型(単眼型や両眼型。ヘッドマウント型も含む。)を包含するアイウェア型、シャツや靴下、帽子等に例えばアクセサリの形態で取り付ける衣服型、イヤホンのように耳に取り付けるイヤウェア型等)、デジタルカメラ、デジタルビデオカメラ、音響機器(携帯音楽プレーヤー、ICレコーダー等)、計算機(電卓等)、携帯ゲーム機器、電子辞書、電子手帳、電子書籍、車載用情報機器、携帯ラジオ、携帯テレビ、携帯プリンター、携帯スキャナ、携帯モデム等が含まれる。携帯電子機器以外の携帯機器の非限定的な例には、機械式の腕時計や懐中時計、懐中電灯、手鏡、定期入れ等が含まれる。なお、この明細書において「携帯」とは、単に携帯することが可能であるだけでは充分ではなく、個人(標準的な成人)が相対的に容易に持ち運び可能なレベルの携帯性を有することを意味するものとする。
(1) 携帯電子機器であって、
表示部が入力部としても機能するタッチパネルを備え、
前記携帯電子機器を構成する部材(複数形)は、粘着シートを介して接合されており、
前記粘着シートは、発泡体基材と、該発泡体基材の少なくとも一方の面に設けられた粘着剤層と、を備えており、
前記粘着剤層は、ベースポリマーとしてのアクリル系ポリマーを含み、
前記粘着剤層は、65℃における貯蔵弾性率G´(65℃)が30000Paよりも大きい、携帯電子機器。
(2) 前記携帯電子機器の内部空間において、回路板が折り曲げられて収容されており、前記粘着シートは前記回路板を折り曲げた状態で固定している、上記(1)に記載の携帯電子機器。
(3) 有機ELディスプレイを有する、上記(1)または(2)に記載の携帯電子機器。
(4) 携帯電話である、上記(1)~(3)のいずれかに記載の携帯電子機器。
(5) スマートフォンである、上記(1)~(3)のいずれかに記載の携帯電子機器。
(6) タブレット型パソコンである、上記(1)~(3)のいずれかに記載の携帯電子機器。
(7) ウェアラブル機器である、上記(1)~(3)のいずれかに記載の携帯電子機器。
(8) 携帯ゲーム機器である、上記(1)~(3)のいずれかに記載の携帯電子機器。
(9) 電子辞書である、上記(1)~(3)のいずれかに記載の携帯電子機器。
(10) 電子書籍である、上記(1)~(3)のいずれかに記載の携帯電子機器。
前記粘着剤層は、ベースポリマーとしてのアクリル系ポリマーを含み、
前記粘着剤層は、65℃における貯蔵弾性率G´(65℃)が30000Paよりも大きい、粘着シート。
(12) 前記アクリル系ポリマーを構成するモノマー成分は、エステル末端に炭素原子数1~6のアルキル基を有するアルキル(メタ)アクリレートを50重量%よりも多く含む、上記(11)に記載の粘着シート。
(13) 前記アクリル系ポリマーを構成するモノマー成分は、カルボキシ基含有モノマーを含む、上記(11)または(12)に記載の粘着シート。
(14) 前記モノマー成分における前記カルボキシ基含有モノマーの量は1~10重量%である、上記(13)に記載の粘着シート。
(15) 前記粘着剤層を形成するための粘着剤組成物はイソシアネート系架橋剤を含む、上記(11)~(14)のいずれかに記載の粘着シート。
(16) 前記粘着剤層は、上記ベースポリマーに加えて、粘着付与成分として、粘着付与樹脂および(メタ)アクリル系オリゴマーから選択される少なくとも1種を含む、上記(11)~(15)のいずれかに記載の粘着シート。
(17) 前記粘着剤層は、水酸基価が70mgKOH/g以上の粘着付与樹脂を含む、上記(11)~(16)のいずれかに記載の粘着シート。
(18) 前記粘着付与樹脂はフェノール系粘着付与樹脂を含む、上記(11)~(17)のいずれかに記載の粘着シート。
(19) 前記粘着剤層における前記粘着付与樹脂の含有量は、前記ベースポリマー100重量部に対して10重量部以上60重量部以下である、上記(11)~(18)のいずれかに記載の粘着シート。
(20) 前記粘着剤層は、tanδのピーク温度から求められるガラス転移温度が-25℃以上25℃以下の範囲にある、上記(11)~(19)のいずれかに記載の粘着シート。
(21) 総厚さが100μm以上である、上記(11)~(20)のいずれかに記載の粘着シート。
(22) 前記発泡体基材はポリオレフィン系発泡体基材である、上記(11)~(21)のいずれかに記載の粘着シート。
(24) 前記発泡体基材の平均気泡径は10~200μmである、上記(11)~(23)のいずれかに記載の粘着シート。
(26) 携帯電子機器において、回路板を固定するために用いられる、上記(11)~(25)のいずれかに記載の粘着シート。
(27) 携帯電子機器内において、折り曲げた状態で収容された回路板を固定するために用いられる、上記(11)~(26)のいずれかに記載の粘着シート。
(28) 有機ELディスプレイを有する携帯電子機器の部品を接合するために用いられる、上記(11)~(27)のいずれかに記載の粘着シート。
(29) 上記(11)~(28)のいずれかに記載の粘着シートと、該粘着シートによって接合された部品と、を備える携帯機器。
(30) 前記携帯電子機器の内部空間において、回路板が折り曲げられて収容されており、前記粘着シートは前記回路板を折り曲げた状態で固定している、上記(29)に記載の携帯電子機器。
[動的粘弾性測定]
片面がシリコーン系剥離処理剤で剥離処理された厚さ38μmのPETフィルムの剥離面に粘着剤組成物を塗布し、100℃で2分間乾燥させることにより、上記剥離面上に厚さ50μmの粘着剤層を形成する。この厚さ50μmの粘着剤層を重ね合わせることにより、厚さ約2mmの積層粘着剤サンプルを作製する。上記積層粘着剤サンプルを直径7.9mmの円盤状に打ち抜いた試料をパラレルプレートで挟み込んで固定し、粘弾性試験機(ティー・エー・インスツルメント社製、機種名「ARES」)により以下の条件で動的粘弾性測定を行い、65℃貯蔵弾性率[Pa]および65℃損失弾性率[Pa]を求める。この測定方法により、粘着剤層のTg(tanδのピーク温度)、tanδ(G”/G’)ピークにおけるピーク強度、25℃貯蔵弾性率(G’(25℃))および25℃損失弾性率(G”(25℃))も求めることができる。
(測定条件)
・測定モード:せん断モード
・温度範囲 :-70℃~150℃
・昇温速度 :5℃/min
・測定周波数:1Hz
約0.1gの粘着剤サンプル(重量Wg1)を平均孔径0.2μmの多孔質ポリテトラフルオロエチレン膜(重量Wg2)で巾着状に包み、口をタコ糸(重量Wg3)で縛る。上記多孔質ポリテトラフルオロエチレン(PTFE)膜としては、日東電工社から入手可能な商品名「ニトフロン(登録商標)NTF1122」(平均孔径0.2μm、気孔率75%、厚さ85μm)またはその相当品を使用する。
この包みを酢酸エチル50mLに浸し、室温(典型的には23℃)で7日間保持して粘着剤層中のゾル成分のみを上記膜外に溶出させた後、上記包みを取り出して外表面に付着している酢酸エチルを拭き取り、該包みを130℃で2時間乾燥させ、該包みの重量(Wg4)を測定する。粘着剤層のゲル分率FGは、各値を以下の式に代入することにより求められる。後述の実施例においても同様の方法が採用される。
ゲル分率FG(%)=[(Wg4-Wg2-Wg3)/Wg1]×100
図2の(a)に示すように、長さ30mm、幅10mm、厚さ2mmのPC板50の一方の表面全体を覆うように厚さ125μmのPETフィルム52を積層固定する。また、長さ70mm、幅10mm、厚さ125μmのPETフィルム60を用意し、PC板50とPETフィルム60の長手方向の一端を揃えるようにして重ね合わせ、PETフィルム60の残りの部分がPC板50の他端から突出した状態でPC板50とPETフィルム60とを固定する。上記固定には市販の両面粘着テープ(日東電工社製、「No.5000NS」)を使用する。
2枚の剥離ライナーで両粘着面が保護された粘着シートを幅3mm、長さ10mmのサイズにカットして粘着シート試料片70を用意する。PC板50に積層されたPETフィルム52の表面を上側に設置し、上記粘着シート試料片70から一方の剥離ライナーを剥がして、PC板50の幅方向と粘着シート試料片70の長手方向とを一致させて、PC板50に積層固定されたPETフィルム52の上面において他端から7mmおよび10mmの線上に粘着シート試料片70の幅方向両端が来るようにして粘着シート試料片70をPETフィルム52上面に貼り付け固定する。上記固定は、粘着シート試料片70のもう一方の剥離ライナーで保護された上面を2kgローラを一往復させることによって行う。
次いで、23℃、50%RHの環境下にて、PETフィルム52に貼り付けた粘着シート試料片70のもう一方の剥離ライナーを剥がして、図2の(b)に示すように、PC板50に固定されたPETフィルム60のPC板50からの突出部分(長さ40mm)をPC板50側に折り返して、粘着シート試料片70とPETフィルム60の他端(自由端)とを一致させて、プレス機を用いて0.5MPa、0.5秒間の条件で圧着することにより、折り曲げられたPETフィルム60の他端を粘着シート試料片70を介してPC板50上のPETフィルム52上面に固定する。圧着後、65℃90%RHの環境下に72時間放置し、PETフィルム60が粘着シート試料片70から剥離するかどうかをZ軸方向耐変形性(65℃90%RH)として評価する。粘着シート試料片70とPETフィルム60との接着状態が保持された場合を「合格」、図2の(c)に示すようにPETフィルム60が剥がれた場合を「不合格」と判定する。
この評価方法によると、従来の耐反撥性評価と異なり、実質的に粘着シートの厚さ方向(Z軸方向)のみからなる引き剥がし荷重に対する高温高湿条件下での耐変形性を評価することが可能であり、さらに経時的な観察を行うことにより持続的な耐変形性を評価することができる。
剥離ライナーで粘着面が保護された粘着シート(両面粘着シート)を2mmの幅で外径24.5mm角の枠状に打ち抜き、窓枠状粘着シートを得る。また、厚さ2mm、外形50mm×50mmの正方形の中央部に孔の開いたステンレスプレートと、正方形のPET板(外形25mm角、厚さ2mm)とを用意し、両者の間に、剥離ライナーを除去した窓枠状粘着シートを配置し、62N、10秒の条件で均一に圧力がかかるように圧着することにより、ステンレスプレートとPET板とを窓枠状粘着シートで固定する。これを50℃の環境に2時間静置し、取り出した後、23℃に戻す。これを評価用サンプルとする。デュポン式衝撃試験機(東洋精機製作所社製)の台座の上に、長さ50mm、外径49mm、内径43mmの円筒状の測定台を設置する。その上に、評価用サンプルを、正方形のPET板を下側にして載せる。評価用サンプルは、上側のステンレスプレートが測定台に支持されており、下側のPET板は、上記窓枠状粘着シートによって上記ステンレスプレートに接着された状態で上記測定台内の中空部分に入るように配置されている。先端半径3.1mmのステンレス製の撃芯(撃ち型)を評価用サンプル下側のPET板上に載せ、23℃50%RHにて、以下の条件(おもり重量および落下高さ)で、おもりを撃芯に落下させる。おもり重量およびおもり落下高さは、最もエネルギー量が小さい条件からスタートし、エネルギー量が増加するように条件を変えていく。おもり落下高さは50mm間隔で増加させる。おもりの変更に際して、測定済みのエネルギー量(おもり重量とおもり落下高さから求められるエネルギー量)については測定は行わず、エネルギー量が重複しない条件(おもり重量×おもり落下高さ)を設定し、おもり落下試験を実施するものとする。
(おもり重量) (おもり落下高さ)
100g 50mm~500mm
150g 350mm~500mm
200g 400mm~500mm
300g 350mm~500mm
ステンレスプレートとPET板との剥がれが生じる一つ前の条件のエネルギー量(J)をおもり重量(荷重)および落下高さから算出し、これを耐衝撃性の測定値として記録する。上記測定値が0.2J以上であれば、耐衝撃性に優れるといえる。
両面粘着シートの一方の粘着面を覆う剥離ライナーを剥がし、厚さ50μmのPETフィルムに貼り付けて裏打ちする。この裏打ちされた粘着シートを幅10mm、長さ100mmのサイズにカットして測定サンプルを作製する。上記測定サンプルの他方の粘着面を覆う剥離ライナーを剥がし、該他方の粘着面を被着体としてのベークライト板に2kgのローラを1往復させて圧着する。その後、ベークライト板への接着長さが20mm(したがって接着面積200mm2:10mm幅×20mm長さ)となるよう測定サンプルをカットする。このようにして被着体に貼り付けられた測定サンプルを80℃の環境下に垂下して30分間放置した後、該測定サンプルの自由端に1kgの荷重を付与し、該荷重が付与された状態で80℃の環境下に1時間放置する。1時間後、測定サンプルが被着体に保持されていた場合を「合格」とし、1時間以内に測定サンプルが被着体から剥がれて落下した場合を「不合格」と判定する。
なお、片面粘着シートの場合、上記PETフィルムの裏打ちは不要である。
23℃、50%RHの測定環境下において、両面粘着シートの一方の粘着面に厚さ50μmのPETフィルムを貼り付けて裏打ちし、幅20mm、長さ100mmのサイズにカットして測定サンプルを作製する。23℃、50%RHの環境下にて、上記測定サンプルの他方の粘着面をステンレス鋼板(SUS304BA板)の表面に、2kgのローラを1往復させて圧着する。これを同環境下に30分間放置した後、10℃の条件にて、万能引張圧縮試験機を使用して、引張速度1000mm/分、剥離角度180度の条件で、剥離強度[N/20mm]を測定する。これを低温接着力として記録する。万能引張圧縮試験機としては、ミネベア社製の「引張圧縮試験機、TG-1kN」またはその相当品が用いられる。なお、片面粘着シートの場合、上記PETフィルムの裏打ちは不要である。
攪拌機、温度計、窒素ガス導入管、還流冷却器および滴下ロートを備えた反応容器に、モノマー成分としてのBA95部およびAA5部と、重合溶媒としての酢酸エチル233部とを仕込み、窒素ガスを導入しながら2時間撹拌した。このようにして重合系内の酸素を除去した後、重合開始剤として0.2部のAIBNを加え、60℃で8時間溶液重合してアクリル系ポリマーA1の溶液を得た。このアクリル系ポリマーA1のMwは約60×104~70×104であり、Mw/Mnは約4~5であった。
上記アクリル系ポリマーA1の溶液に、アクリル系ポリマー100部に対して、粘着付与樹脂B1(製品名「YSポリスター S145」、ヤスハラケミカル社製、テルペンフェノール樹脂、軟化点145℃、水酸基価70~110mgKOH/g)を30部、イソシアネート系架橋剤(商品名「コロネートL」、トリメチロールプロパン/トリレンジイソシアネート3量体付加物の75%酢酸エチル溶液、東ソー社製)を2部(固形分換算)、エポキシ系架橋剤(商品名「TETRAD-C」、1,3-ビス(N,N-ジグリシジルアミノメチル)シクロへキサン、三菱瓦斯化学社製)を0.01部(固形分換算)配合し、撹拌混合して、本例に係る粘着剤組成物を調製した。
市販の剥離ライナー(商品名「SLB-80W3D」、住化加工紙社製)を2枚用意し、それらの剥離ライナーのそれぞれ一方の面(剥離面)に粘着剤組成物を、乾燥後の厚さが40μmとなるように塗布し、100℃で2分間乾燥させることにより、上記2枚の剥離ライナーの剥離面上にそれぞれ粘着剤層を形成した。これらの粘着剤層を、両面にコロナ放電処理が施されたポリエチレン系発泡体シート(厚さ200μm、密度0.43g/cm3、10%圧縮強度(C10)330kPa、25%圧縮強度(C25)942kPa、30%圧縮強度(C30)1235kPa、平均気泡径55μm)の両面にそれぞれ貼り合わせた。上記剥離ライナーは、そのまま粘着剤層上に残し、該粘着剤層の表面(粘着面)の保護に使用した。得られた構造体を80℃のラミネータ(0.3MPa、速度0.5m/分)に1回通過させた後、50℃のオーブン中で1日間養生した。このようにして本例に係る粘着シート(発泡体基材付き両面粘着シート)を得た。
粘着剤層の厚さおよび発泡体基材の厚さを変更した他は上記例1と同様にして、各例に係る発泡体基材付き両面粘着シートを得た。
モノマー組成をBA100部、VAc3部、AA5部およびHEA0.1部に変更し、重合溶媒としてトルエンを使用した他は例1と基本的に同様にして、Mw50×104~60×104のアクリル系ポリマーA2の溶液を得た。
上記アクリル系ポリマーA2の溶液中に、アクリル系ポリマー100部に対し、粘着付与樹脂35部と、イソシアネート系架橋剤(商品名「コロネートL」、東ソー社製)2部(固形分換算)とを配合し、撹拌混合して、本例に係るアクリル系粘着剤組成物を調製した。
粘着付与樹脂としては、粘着付与樹脂B2(製品名「スミライトレジン PR-12603N」、住友ベークライト社製、テルペン変性フェノール系樹脂、軟化点130~140℃、水酸基価1~20mgKOH/g)を15部、粘着付与樹脂B3(製品名「ハリタック SE10」、ハリマ化成社製、水添ロジングリセリンエステル、軟化点75~85℃、水酸基価25~40mgKOH/g)を10部、粘着付与樹脂B4(製品名「ハリタック PCJ」、ハリマ化成社製、重合ロジンエステル、軟化点118~128℃)を10部使用した。
上記アクリル系粘着剤組成物を使用した他は上記例2と同様にして、厚さ25μmの粘着剤層を発泡体基材(厚さ150μm)の両面に有する粘着シート(発泡体基材付き両面粘着シート)を得た。
モノマー組成をBA70部、2EHA30部、AA3部および4-HBA0.05部に変更した他は例6と基本的に同様にして、Mw44×104のアクリル系ポリマーA3の溶液を得た。
上記アクリル系ポリマーA3の溶液中に、アクリル系ポリマー100部に対し、粘着付与樹脂B5(製品名「ペンセル D-125」、荒川化学工業社製、ロジンエステル系樹脂、軟化点120~130℃)30部と、イソシアネート系架橋剤(商品名「コロネートL」、東ソー社製)3部(固形分換算)とを配合し、撹拌混合して、本例に係るアクリル系粘着剤組成物を調製した。
上記アクリル系粘着剤組成物を使用した他は例2と同様にして、厚さ25μmの粘着剤層を発泡体基材(厚さ150μm)の両面に有する粘着シート(発泡体基材付き両面粘着シート)を得た。
例1で用意した粘着剤組成物を用い、発泡体基材に代えて厚さ50μmのPETフィルムを基材として用い、PETフィルム基材の両面に厚さ50μmの粘着剤層を形成し、本例に係るPETフィルム基材付き両面粘着シートを得た。
限定するものではない。特許請求の範囲に記載の技術には、以上に例示した具体例を様々
に変形、変更したものが含まれる。
10 発泡体基材
10A 第1面
10B 第2面
21 第1粘着剤層
22 第2粘着剤層
21A 第1粘着面
22A 第2粘着面
31,32 剥離ライナー
Claims (10)
- 発泡体基材と、該発泡体基材の少なくとも一方の面に設けられた粘着剤層と、を備える粘着シートであって、
前記粘着剤層は、ベースポリマーとしてのアクリル系ポリマーを含み、
前記粘着剤層は、65℃における貯蔵弾性率G´(65℃)が30000Paよりも大きい、粘着シート。 - 前記アクリル系ポリマーを構成するモノマー成分は、エステル末端に炭素原子数1~6のアルキル基を有するアルキル(メタ)アクリレートを50重量%よりも多く含む、請求項1に記載の粘着シート。
- 前記アクリル系ポリマーを構成するモノマー成分は、カルボキシ基含有モノマーを含む、請求項1または2に記載の粘着シート。
- 前記モノマー成分における前記カルボキシ基含有モノマーの量は1~10重量%である、請求項3に記載の粘着シート。
- 前記粘着剤層を形成するための粘着剤組成物はイソシアネート系架橋剤を含む、請求項1~4のいずれか一項に記載の粘着シート。
- 前記粘着剤層は、水酸基価が70mgKOH/g以上の粘着付与樹脂を含む、請求項1~5のいずれか一項に記載の粘着シート。
- 前記粘着剤層における前記粘着付与樹脂の含有量は、前記ベースポリマー100重量部に対して10重量部以上60重量部以下である、請求項1~6のいずれか一項に記載の粘着シート。
- 総厚さが100μm以上である、請求項1~7のいずれか一項に記載の粘着シート。
- 前記発泡体基材はポリオレフィン系発泡体基材である、請求項1~8のいずれか一項に記載の粘着シート。
- 携帯電子機器の部品を接合するために用いられる、請求項1~9のいずれか一項に記載の粘着シート。
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- 2019-07-09 KR KR1020217002874A patent/KR20210031472A/ko not_active Application Discontinuation
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CN112400001B (zh) | 2023-03-17 |
JPWO2020013168A1 (ja) | 2021-07-15 |
CN110699008B (zh) | 2023-04-25 |
CN112400001A (zh) | 2021-02-23 |
JP7469856B2 (ja) | 2024-04-17 |
KR20210031472A (ko) | 2021-03-19 |
CN110699008A (zh) | 2020-01-17 |
JP2020012108A (ja) | 2020-01-23 |
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