CN106916540B - Adhesive sheet and display - Google Patents

Adhesive sheet and display Download PDF

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Publication number
CN106916540B
CN106916540B CN201610903624.3A CN201610903624A CN106916540B CN 106916540 B CN106916540 B CN 106916540B CN 201610903624 A CN201610903624 A CN 201610903624A CN 106916540 B CN106916540 B CN 106916540B
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Prior art keywords
adhesive
adhesive layer
layer
constituting
meth
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CN106916540A (en
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渡边旭平
荒井隆行
所司悟
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Lintec Corp
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Lintec Corp
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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
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
    • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
    • C08F220/10—Esters
    • C08F220/12—Esters of monohydric alcohols or phenols
    • C08F220/14—Methyl esters, e.g. methyl (meth)acrylate
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
    • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
    • C08F220/10—Esters
    • C08F220/12—Esters of monohydric alcohols or phenols
    • C08F220/16—Esters of monohydric alcohols or phenols of phenols or of alcohols containing two or more carbon atoms
    • C08F220/18—Esters of monohydric alcohols or phenols of phenols or of alcohols containing two or more carbon atoms with acrylic or methacrylic acids
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
    • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
    • C08F220/10—Esters
    • C08F220/26—Esters containing oxygen in addition to the carboxy oxygen
    • C08F220/28—Esters containing oxygen in addition to the carboxy oxygen containing no aromatic rings in the alcohol moiety
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
    • C09J11/02—Non-macromolecular additives
    • C09J11/06—Non-macromolecular additives organic
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • 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
    • 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
    • C09J4/00—Adhesives based on organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond ; adhesives, based on monomers of macromolecular compounds of groups C09J183/00 - C09J183/16
    • C09J4/06—Organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond in combination with a macromolecular compound other than an unsaturated polymer of groups C09J159/00 - C09J187/00
    • 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
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
    • G09F9/00—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements
    • G09F9/30—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements in which the desired character or characters are formed by combining individual elements
    • G09F9/33—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements in which the desired character or characters are formed by combining individual elements being semiconductor devices, e.g. diodes
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
    • G09F9/00—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements
    • G09F9/30—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements in which the desired character or characters are formed by combining individual elements
    • G09F9/35—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements in which the desired character or characters are formed by combining individual elements being liquid crystals
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00—Use of organic ingredients
    • C08K5/16—Nitrogen-containing compounds
    • C08K5/205—Compounds containing groups, e.g. carbamates
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00—Use of organic ingredients
    • C08K5/54—Silicon-containing compounds
    • C08K5/541—Silicon-containing compounds containing oxygen
    • C08K5/5435—Silicon-containing compounds containing oxygen containing oxygen in a ring
    • 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
    • C09J2203/318—Applications of adhesives in processes or use of adhesives in the form of films or foils for the production of liquid crystal displays
    • 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
    • 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
    • C09J2301/124—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 on both sides of the carrier, e.g. double-sided adhesive tape
    • 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
    • C09J2301/20—Additional features of adhesives in the form of films or foils characterized by the structural features of the adhesive itself
    • C09J2301/208—Additional features of adhesives in the form of films or foils characterized by the structural features of the adhesive itself the adhesive layer being constituted by at least two or more adjacent or superposed adhesive layers, e.g. multilayer adhesive
    • 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
    • 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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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Theoretical Computer Science (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Adhesive Tapes (AREA)
  • Adhesives Or Adhesive Processes (AREA)

Abstract

The invention provides an adhesive sheet and a display. The adhesive sheet (1) is provided with an adhesive layer (2), wherein the adhesive layer (2) is provided with: a first adhesive layer (21) which is an outer layer on one surface side; a second adhesive layer (22) which is an outer layer on the other surface side: and a third adhesive layer (23) which is located between the first adhesive layer (21) and the second adhesive layer (22) as an intermediate layer, wherein the storage modulus (G ') of the adhesive constituting the first adhesive layer (21) and the storage modulus (G ') of the adhesive constituting the second adhesive layer (22) at 23 ℃ are respectively 0.1MPa or more, and the third adhesive layer (23) is composed of an active energy ray-curable adhesive, and the storage modulus (G ') of the active energy ray-curable adhesive before curing is lower than the storage modulus (G ') of the adhesive constituting the first adhesive layer (21) and the storage modulus (G ') of the adhesive constituting the second adhesive layer (22).

Description

Adhesive sheet and display
Technical Field
The present invention relates to an adhesive sheet suitable for bonding display constituent members, and a display obtained using an adhesive layer of the adhesive sheet.
Background
In recent years, various mobile electronic devices such as smartphones and tablet computers have displays using display modules, which are generally touch panels, including liquid crystal elements, light emitting diodes (LED elements), organic electroluminescence (organic EL) elements, and the like.
In the display device as described above, a protective panel is generally provided on the front surface side of the display body module. With the reduction in thickness and weight of electronic devices, the protective panel has been changed from a conventional glass plate to a plastic plate such as an acrylic plate or a polycarbonate plate.
In the process, a gap is arranged between the protection panel and the display body module so as to prevent the protection panel which deforms when the protection panel deforms due to external force from colliding with the display body module.
However, if there is the air layer, which is the above-described void, the reflection loss of light due to the difference in refractive index between the protective panel and the air layer and the difference in refractive index between the air layer and the display module increases, and there is a problem that the image quality of the display device is degraded.
Therefore, it is proposed to fill the gap between the protective panel and the display module with an adhesive layer to improve the image quality of the display. However, the frame-like printed layer may be present as a step difference on the display module side of the protective panel. If the adhesive layer does not follow the step, the adhesive layer floats up in the vicinity of the step, and reflection loss of light occurs. Therefore, the adhesive layer is required to have step following properties.
In order to solve the above problems, patent document 1 discloses an adhesive layer having a shear storage modulus (G') of 1.0 × 105Pa or less at 25 ℃ and 1Hz and a gel fraction of 40% or more as an adhesive layer filling a gap between a protective panel and a display module.
In the invention disclosed in patent document 1, the step following property is intended to be improved by lowering the storage modulus (G') at room temperature in the adhesive agent layer. However, if the storage modulus (G ') at normal temperature is lowered as described above, the storage modulus (G') at high temperature is excessively lowered, which causes a problem under a durable condition. For example, when high-temperature and high-humidity conditions are applied, bubbles are generated in the vicinity of the step, or foaming phenomena such as bubbles, floating, and peeling are generated due to outgas (outgas) generated from a plastic plate as a protective panel. On the other hand, when the adhesive agent layer is cured to improve blister resistance, step following property is lowered.
In addition, when the storage modulus (G') of the adhesive agent layer is reduced as described above, the film strength of the adhesive agent layer is reduced, and the workability is deteriorated. For example, when the adhesive sheet is subjected to punching or the like, the adhesive may overflow from the cut surface, causing a problem that the adhesive adheres to the blade.
On the other hand, in order to solve the problems of the step following property and the processability, patent document 2 discloses an adhesive sheet comprising: the adhesive layer is composed of two or more layers, the storage shear elastic modulus of the intermediate layer is set to be higher than that of the surface layer, and the press-in hardness of the entire sheet is set within a predetermined range.
Documents of the prior art
Patent document
Patent document 1: japanese patent application laid-open No. 2010-97070
Patent document 2: japanese laid-open patent publication No. 2012-184390
Disclosure of Invention
Technical problem to be solved by the invention
However, the adhesive sheet of patent document 2 has a problem that foaming occurs when the sheet is adhered to a protective panel made of a plastic plate and placed under high-temperature and high-humidity conditions because the storage shear modulus of elasticity of the surface layer is low.
The present invention has been made in view of the above circumstances, and an object thereof is to provide an adhesive sheet and a display body in which an adhesive layer is excellent in both of step difference following property and blister resistance and which are excellent in processability.
Means for solving the problems
In order to achieve the above object, a first aspect of the present invention provides an adhesive sheet including an adhesive layer, the adhesive layer including: a first adhesive layer which is an outer layer on one surface side; a second adhesive layer which is an outer layer on the other surface side; and a third adhesive layer which is located between the first adhesive layer and the second adhesive layer as an intermediate layer, wherein the storage modulus (G ') at 23 ℃ of the adhesive constituting the first adhesive layer and the storage modulus (G ') at 23 ℃ of the adhesive constituting the second adhesive layer are respectively 0.1MPa or more, and the third adhesive layer is composed of an active energy ray-curable adhesive, and the storage modulus (G ') at 23 ℃ before curing of the active energy ray-curable adhesive is lower than the storage modulus (G ') at 23 ℃ of the adhesive constituting the first adhesive layer and the storage modulus (G ') at 23 ℃ of the adhesive constituting the second adhesive layer (invention 1).
The second aspect of the present invention provides an adhesive sheet including an adhesive layer, the adhesive layer including: a first adhesive layer which is an outer layer on one surface side; a second adhesive layer which is an outer layer on the other surface side; and a third adhesive layer which is located between the first adhesive layer and the second adhesive layer as an intermediate layer, wherein the 100% modulus of the adhesive constituting the first adhesive layer and the 100% modulus of the adhesive constituting the second adhesive layer are 60kPa or more, respectively, the third adhesive layer is composed of an active energy ray-curable adhesive, and the 100% modulus before curing of the active energy ray-curable adhesive is lower than the 100% modulus of the adhesive constituting the first adhesive layer and the 100% modulus of the adhesive constituting the second adhesive layer (invention 2).
According to the above-described invention (invention 1, invention 2), since the adhesive agent layer includes the third adhesive agent layer having a low storage modulus (G ') before curing or a low 100% modulus as the intermediate layer, the adhesive agent layer is excellent in initial step following property, and the first adhesive agent layer and the second adhesive agent layer as the outer layers have a high storage modulus (G') or a high 100% modulus, and the third adhesive agent layer is cured by irradiation of an active energy ray, the adhesive agent layer is excellent in step following property even under high temperature and high humidity conditions. In addition, in the adhesive agent layer, the first adhesive agent layer and the second adhesive agent layer as the outer layers have a high storage modulus (G') or 100% modulus, and the third adhesive agent layer is cured by irradiation with an active energy ray, whereby the blister resistance is excellent. In addition, in the adhesive agent layer, the first adhesive agent layer and the second adhesive agent layer having a high storage modulus (G ') or a high 100% modulus are used as outer layers, and the third adhesive agent layer having a low storage modulus (G ') or a low 100% modulus before curing is used as an intermediate layer, so that the cross-sectional area of the adhesive agent layer having a low storage modulus (G ') or a low 100% modulus before curing is reduced, whereby the processability is improved.
In the above inventions (inventions 1 and 2), the adhesive constituting the first adhesive layer and the adhesive constituting the second adhesive layer are active energy ray non-curable adhesives (invention 3).
In the above inventions (inventions 1 to 3), a ratio of a thickness of the third adhesive agent layer to a total thickness of the first adhesive agent layer and the second adhesive agent layer is preferably 0.3 or more and 5 or less (invention 4).
In the above inventions (inventions 1 to 4), the total thickness of the adhesive agent layer is preferably 50 μm or more and 300 μm or less (invention 5).
In the above-described inventions (inventions 1 to 5), the bonding method is preferably used for bonding one display body constituting member and another display body constituting member having a step on at least one bonded surface (invention 6).
In the above inventions (inventions 1 to 6), it is preferable that the adhesive sheet includes two release sheets, and the adhesive layer is sandwiched between the two release sheets so as to be in contact with release surfaces of the two release sheets (invention 7).
A third aspect of the present invention provides a display device, including: a display body constituting member having a step at least on one bonded side surface; another display body constituting member; and an adhesive layer for bonding the one display structure member and the other display structure member to each other, wherein the adhesive layer is an adhesive layer obtained by curing the adhesive layer of the adhesive sheet (inventions 1 to 7) (invention 8).
Effects of the invention
The adhesive layer of the adhesive sheet and the display of the present invention is excellent in both step-following property and blister resistance, and has good processability.
Drawings
Fig. 1 is a sectional view of an adhesive sheet according to an embodiment of the present invention.
Fig. 2 is a sectional view of a laminate according to an embodiment of the present invention.
Description of the reference numerals
1: an adhesive sheet; 2: an adhesive layer; 21: a first adhesive layer; 22: a second adhesive layer; 23: a third adhesive layer; 31. 32: a release sheet; 4: a display body; 51: a first display body constituting member; 52: a second display body constituting member; 6: printing layer
Detailed Description
Hereinafter, embodiments of the present invention will be described.
[ adhesive sheet ]
Fig. 1 shows a cross-sectional view of an adhesive sheet according to an embodiment of the present invention.
As shown in fig. 1, the adhesive sheet 1 of the present embodiment is composed of two release sheets 31, 32 and an adhesive layer 2, and the adhesive layer 2 is sandwiched between the two release sheets 31, 32 so as to be in contact with the release surfaces of the two release sheets 31, 32. The release surface of the release sheet in the present specification means a surface having releasability in the release sheet, and includes any one of a surface subjected to a release treatment and a surface showing releasability even if the release treatment is not performed.
The adhesive layer 2 in the present embodiment includes: a first adhesive layer 21 which is an outer layer on one surface side (the release sheet 31 side); a second adhesive layer 22 which is an outer layer on the other surface side (release sheet 32 side); and a third adhesive layer 23 as an intermediate layer between the first adhesive layer 21 and the second adhesive layer 22. In the present embodiment, the first adhesive layer 21 and the second adhesive layer 22 are respectively outermost layers of the adhesive layer 2, the first adhesive layer 21 is in contact with the release surface of the release sheet 31, and the second adhesive layer 22 is in contact with the release surface of the release sheet 32, but the present invention is not limited thereto.
In the present embodiment, the storage modulus (G ') at 23 ℃ of the adhesive constituting the first adhesive layer 21 and the storage modulus (G') of the adhesive constituting the second adhesive layer 22 are 0.1MPa or more, respectively. The third adhesive layer 23 is made of an active energy ray-curable adhesive. The storage modulus (G ') at 23 ℃ before curing (before curing by irradiation with active energy rays) of the active energy ray-curable adhesive is set to be lower than the storage modulus (G ') at 23 ℃ of the adhesive constituting the first adhesive layer 21 and the storage modulus (G ') at 23 ℃ of the adhesive constituting the second adhesive layer 22 (the above is the first alternative condition).
Alternatively, the 100% modulus of each of the adhesive constituting the first adhesive layer 21 and the adhesive constituting the second adhesive layer 22 in the present embodiment is 60kPa or more. The third adhesive layer 23 is made of an active energy ray-curable adhesive. The 100% modulus before curing (before curing by irradiation with active energy rays) of the active energy ray-curable adhesive is set to be lower than the 100% modulus of the adhesive constituting the first adhesive layer 21 and the 100% modulus of the adhesive constituting the second adhesive layer 22 (the above is the second alternative condition).
The adhesive agent layer 2 in the present embodiment has the 3-layer structure, and each of the adhesive agent layer 21, the adhesive agent layer 22, and the adhesive agent layer 23 satisfies the above requirements, and thus is excellent in both step following property and blister resistance, and has good processability. That is, the adhesive agent layer 2 in the present embodiment includes the third adhesive agent layer 23 having a low storage modulus (G') before curing or a low 100% modulus as the intermediate layer, and thus the adhesive agent layer 2 is excellent in initial level difference followability. Further, the first adhesive agent layer 21 and the second adhesive agent layer 22 as the outer layers have a high storage modulus (G') or 100% modulus, and the third adhesive agent layer 23 is cured by irradiation with an active energy ray, whereby the step following property is excellent even under high-temperature and high-humidity conditions. For example, when the adhesive sheet of the present embodiment is attached to a display body constituting member having a level difference, generation of a gap, floating, or the like in the vicinity of the level difference can be suppressed. In addition, even when the sheet is left to stand under high temperature and high humidity conditions, for example, 85 ℃ and 85% RH for 72 hours in this state, the occurrence of bubbles, floating, peeling, and the like in the vicinity of the step difference can be suppressed. In the adhesive agent layer 2 of the present embodiment, the first adhesive agent layer 21 and the second adhesive agent layer 22 as the outer layers have a high storage modulus (G') or 100% modulus, and the third adhesive agent layer 23 is cured by irradiation with an active energy ray, and thus the blister resistance is excellent. For example, even when a display (display) obtained using the adhesive sheet 1 of the present embodiment is left under high-temperature and high-humidity conditions, for example, 85 ℃ and 85% RH for 72 hours, and outgassing occurs from a display component member made of a plastic plate or the like, blistering phenomena such as blistering, lifting, peeling, and the like are suppressed from occurring on the surfaces of the adhesive layer and the display component member. Further, in the adhesive agent layer 2 in the present embodiment, the first adhesive agent layer 21 and the second adhesive agent layer 22 having a high storage modulus (G ') or 100% modulus are used as outer layers, and the third adhesive agent layer 23 having a low storage modulus (G') or 100% modulus before curing is used as an intermediate layer. This reduces the cross-sectional area of the adhesive layer portion having a low storage modulus (G') or 100% modulus before curing in the entire adhesive layer 2, thereby improving the processability. Therefore, for example, it is possible to prevent the adhesive from overflowing from the cut surface and adhering to the blade when the adhesive sheet 1 is subjected to punching or the like.
As described above, as the first alternative condition, the storage modulus (G ') at 23 ℃ of the adhesive constituting the first adhesive layer 21 and the storage modulus (G') at 23 ℃ of the adhesive constituting the second adhesive layer 22 are 0.1MPa or more, preferably 0.12MPa or more, and particularly preferably 0.14MPa or more, respectively. The storage modulus (G') is preferably 0.5MPa or less, particularly preferably 0.25MPa or less, and 0 is more preferably.18 MPa or less. The storage modulus (G') is 0.5MPa or less, and thus the step difference following property of the adhesive layer 2 can be kept high. The storage modulus (G ') at 23 ℃ of the adhesive constituting the first adhesive layer 21 and the storage modulus (G') at 23 ℃ of the adhesive constituting the second adhesive layer 22 may be the same or different.
Further, as a first alternative condition, the storage modulus (G ') at 23 ℃ before curing of the active energy ray-curable adhesive constituting the third adhesive layer 23 is set lower than the storage modulus (G ') at 23 ℃ of the adhesive constituting the first adhesive layer 21 and the storage modulus (G ') at 23 ℃ of the adhesive constituting the second adhesive layer 22. Specifically, the storage modulus (G') is preferably 0.10MPa or less, particularly preferably 0.09MPa or less, and more preferably 0.08MPa or less. This makes it possible to further improve the step difference following property of the adhesive layer 2. The storage modulus (G') is preferably 0.01MPa or more, particularly preferably 0.03MPa or more, and more preferably 0.06MPa or more. This makes it possible to improve the workability of the adhesive layer 2. The method of measuring the storage modulus (G') is shown in test examples described later.
Here, the storage modulus (G') at 23 ℃ after curing (after curing by irradiation with active energy rays) of the active energy ray-curable adhesive constituting the third adhesive layer 23 is preferably 0.1MPa or more, particularly preferably 0.11MPa or more, and more preferably 0.12MPa or more. This makes it possible to further improve the blister resistance and the step following property under high-temperature and high-humidity conditions of the adhesive agent layer 2. On the other hand, the storage modulus (G') is preferably 0.5MPa or less, particularly preferably 0.3MPa or less, and more preferably 0.18MPa or less. This makes it possible to keep the adhesive force of the third adhesive agent layer 23, particularly the adhesive force to the first adhesive agent layer 21 and the second adhesive agent layer 22, high.
In addition, the storage modulus (G ') at 23 ℃ after curing of the active energy ray-curable adhesive constituting the third adhesive layer 23 may be smaller or larger than the storage modulus (G ') at 23 ℃ of the adhesive constituting the first adhesive layer 21 and the storage modulus (G ') at 23 ℃ of the adhesive constituting the second adhesive layer 22, and both may be the same. Among them, the storage modulus (G ') at 23 ℃ after curing of the active energy ray-curable adhesive constituting the third adhesive layer 23 is preferably larger than the storage modulus (G ') at 23 ℃ of the adhesive constituting the first adhesive layer 21 and the storage modulus (G ') at 23 ℃ of the adhesive constituting the second adhesive layer 22. This provides the adhesive layer 2 with more excellent blister resistance and step following properties under high temperature and high humidity conditions.
As described above, as the second alternative condition, the 100% modulus of each of the adhesive constituting the first adhesive layer 21 and the adhesive constituting the second adhesive layer 22 is 60kPa or more, preferably 70kPa or more, and particularly preferably 80kPa or more. The 100% modulus is preferably 150kPa or less, more preferably 140kPa or less, and still more preferably 130kPa or less. The 100% modulus is 150kPa or less, and thus the step difference following property of the adhesive layer 2 can be kept high. The 100% modulus of the adhesive constituting the first adhesive layer 21 and the 100% modulus of the adhesive constituting the second adhesive layer 22 may be the same or different.
As a second alternative condition, the 100% modulus before curing of the active energy ray-curable adhesive constituting the third adhesive layer 23 is set to be lower than the 100% modulus of the adhesive constituting the first adhesive layer 21 and the 100% modulus of the adhesive constituting the second adhesive layer 22. Specifically, the storage modulus (G') is preferably 60kPa or less, more preferably 50kPa or less, and still more preferably 40kPa or less. This makes it possible to further improve the step difference following property of the adhesive layer 2. The 100% modulus is preferably 5kPa or more, particularly preferably 10kPa or more, and further preferably 15kPa or more. This makes it possible to improve the workability of the adhesive layer 2. The method of measuring the 100% modulus is shown in test examples described below.
Here, the 100% modulus after curing (after curing by irradiation with active energy rays) of the active energy ray-curable adhesive constituting the third adhesive layer 23 is preferably 30kPa or more, particularly preferably 40kPa or more, and more preferably 50kPa or more. This makes it possible to further improve the blister resistance and the step following property under high-temperature and high-humidity conditions of the adhesive agent layer 2. On the other hand, the 100% modulus is preferably 300kPa or less, particularly preferably 200kPa or less, and further preferably 180kPa or less. This makes it possible to keep the adhesive force of the third adhesive agent layer 23, particularly the adhesive force to the first adhesive agent layer 21 and the second adhesive agent layer 22, high.
The 100% modulus after curing (after curing by irradiation with an active energy ray) of the active energy ray-curable adhesive constituting the third adhesive layer 23 may be smaller or larger than the 100% modulus of the adhesive constituting the first adhesive layer 21 and the 100% modulus of the adhesive constituting the second adhesive layer 22, and both may be the same. Of these, the 100% modulus after curing of the active energy ray-curable adhesive constituting the third adhesive layer 23 is preferably larger than the 100% modulus of the adhesive constituting the first adhesive layer 21 and the 100% modulus of the adhesive constituting the second adhesive layer 22. This provides the adhesive layer 2 with more excellent blister resistance and step following properties under high temperature and high humidity conditions.
The ratio of the thickness of the third adhesive layer 23 to the total thickness of the first adhesive layer 21 and the second adhesive layer 22 is preferably 0.3 or more, particularly preferably 0.4 or more, and more preferably 0.5 or more. The ratio is preferably 5 or less, particularly preferably 3 or less, further preferably 2 or less, and most preferably 0.8 or less. This ratio falls within the above range, whereby the effects of the step following property, blister resistance and workability described above can be more favorably exhibited. The thickness of each layer was measured according to JIS K7130.
The total thickness of the adhesive layer 2 is preferably 50 μm or more, particularly preferably 75 μm or more, and further preferably 100 μm or more. The total thickness is preferably 300 μm or less, particularly preferably 250 μm or less, and more preferably 200 μm or less. The total thickness of the adhesive layer 2 falls within the above range, whereby the effects of the step following property, blister resistance and processability described above can be more favorably exhibited.
The thickness of the first adhesive agent layer 21 and the thickness of the second adhesive agent layer 22 are each preferably 25 μm or more, particularly preferably 30 μm or more, and more preferably 50 μm or more. The thickness is preferably 100 μm or less, particularly preferably 80 μm or less, and more preferably 75 μm or less. When the thickness is within the above range, the effects of the step following property, blister resistance and workability described above can be more favorably exhibited. The thickness of the first adhesive layer 21 and the thickness of the second adhesive layer 22 may be the same or different.
The thickness of the third adhesive agent layer 23 is preferably 25 μm or more, particularly preferably 30 μm or more, and further preferably 50 μm or more. The thickness is preferably 150 μm or less, particularly preferably 125 μm or less, more preferably 100 μm or less, and most preferably 75 μm or less. The thickness falls within the above range, whereby the effects of the step following property, blister resistance and workability described above can be more favorably exhibited.
1. A first adhesive layer and a second adhesive layer
The adhesive constituting the first adhesive layer and the adhesive constituting the second adhesive layer are not particularly limited as long as the above physical properties are satisfied, and may be an active energy ray-curable adhesive or an active energy ray-non-curable adhesive, but is preferably an active energy ray-non-curable adhesive. This makes it possible to maintain the adhesiveness (adhesive force) to an adherend (particularly, a display constituent member) after the irradiation of the adhesive layer 2 with an active energy ray higher. The adhesive constituting the first adhesive layer and the adhesive constituting the second adhesive layer may be the same adhesive or different adhesives.
Hereinafter, the active energy ray non-curable adhesive will be mainly described. In the case of the active energy ray-curable adhesive, the same adhesive as the active energy ray-curable adhesive constituting the third adhesive layer 23 described later can be used.
The active energy ray non-curable adhesive constituting the first adhesive layer and the second adhesive layer may be any of an acrylic adhesive, a rubber adhesive, a silicone adhesive, an amine ester adhesive, a polyester adhesive, a polyvinyl ether adhesive, and the like. The adhesive may be any of emulsion type, solvent type, and non-solvent type, and may be any of crosslinking type and non-crosslinking type.
Among the above, an acrylic pressure-sensitive adhesive is preferable. In this case, the pressure-sensitive adhesive in the present embodiment is preferably obtained from a pressure-sensitive adhesive composition containing the (meth) acrylate polymer (a) (hereinafter, may be referred to as "pressure-sensitive adhesive composition P"). The adhesive composition P further contains a preferable crosslinking agent (B), and in this case, the adhesive in the present embodiment can be obtained by crosslinking the adhesive composition P. In the present specification, the term (meth) acrylate refers to both acrylate and methacrylate. Other similar terms are also the same. Further, "polymer" also encompasses the concept of "copolymer".
(1) (meth) acrylate ester Polymer (A)
The (meth) acrylate polymer (A) can exhibit preferable tackiness by containing an alkyl (meth) acrylate having 1 to 20 carbon atoms in the alkyl group as a monomer unit constituting the polymer. From this viewpoint, the (meth) acrylate polymer (a) preferably contains an alkyl (meth) acrylate having 1 to 20 carbon atoms and an alkyl group in an amount of 50 mass% or more as a lower limit, particularly preferably 60 mass% or more, and more preferably 70 mass% or more, as a monomer unit constituting the polymer. When the alkyl (meth) acrylate is contained in an amount of 50% by mass or more, the (meth) acrylate polymer (a) can exhibit more preferable tackiness. The (meth) acrylate polymer (a) preferably contains the alkyl (meth) acrylate as a monomer unit constituting the polymer at an upper limit of 97 mass% or less, particularly preferably 90 mass% or less, and more preferably 85 mass% or less. By containing 97% by mass or less of the above-mentioned alkyl (meth) acrylate, a more preferable amount of other monomer components can be introduced into the (meth) acrylate polymer (a).
Examples of the alkyl (meth) acrylate having an alkyl group with 1 to 20 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, n-decyl (meth) acrylate, n-dodecyl (meth) acrylate, tetradecyl (meth) acrylate, hexadecyl (meth) acrylate, octadecyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, adamantyl (meth) acrylate, and the like, among them, from the viewpoint of further improving the adhesiveness, a (meth) acrylate having 4 to 8 carbon atoms and containing an alkyl group is preferable. These may be used alone or in combination of two or more. The alkyl group in the alkyl (meth) acrylate in which the alkyl group has 1 to 20 carbon atoms is a linear, branched or cyclic alkyl group.
In addition, as the alkyl (meth) acrylate having an alkyl group with 1 to 20 carbon atoms, it is preferable to use a hard monomer having a glass transition temperature (Tg) of more than 0 ℃ (preferably 70 ℃ or higher) as a homopolymer and a soft monomer having a glass transition temperature (Tg) of 0 ℃ or lower as a homopolymer in combination. This is because the soft monomer can maintain adhesiveness and flexibility, and the hard monomer can increase the cohesive force, thereby further improving the step following property. In this case, the mass ratio of the hard monomer to the soft monomer is preferably 5:95 to 40:60, and particularly preferably 20:80 to 30: 70.
Examples of the hard monomer include methyl acrylate (Tg10 ℃ C.), methyl methacrylate (Tg105 ℃ C.), isobornyl acrylate (Tg94 ℃ C.), isobornyl methacrylate (Tg180 ℃ C.), adamantyl acrylate (Tg115 ℃ C.), and adamantyl methacrylate (Tg141 ℃ C.), and the like. These may be used alone or in combination of two or more.
Among the above hard monomers, methyl acrylate, methyl methacrylate and isobornyl acrylate are preferable from the viewpoint of preventing adverse effects on other properties such as tackiness and transparency and further exhibiting the performance of the hard monomers. In view of the tackiness, methyl acrylate and methyl methacrylate are more preferable, and methyl methacrylate is particularly preferable.
The soft monomer is preferably an alkyl acrylate having a linear or branched alkyl group having 2 to 12 carbon atoms. For example, 2-ethylhexyl acrylate (Tg-70 ℃ C.), n-butyl acrylate (Tg-54 ℃ C.) and the like are preferable. These may be used alone or in combination of two or more.
The (meth) acrylate polymer (a) preferably contains a reactive functional group-containing monomer as a monomer unit constituting the polymer. The reactive functional group derived from the reactive functional group-containing monomer reacts with the crosslinking agent (B) described later to form a crosslinked structure (three-dimensional network structure), whereby an adhesive having a desired cohesive force can be obtained.
Examples of the reactive functional group-containing monomer contained as a monomer unit constituting the (meth) acrylate polymer (a) include a monomer having a hydroxyl group in the molecule (hydroxyl group-containing monomer), a monomer having a carboxyl group in the molecule (carboxyl group-containing monomer), and a monomer having an amino group in the molecule (amino group-containing monomer). Among these, a hydroxyl group-containing monomer which has excellent reactivity with the crosslinking agent (B) and has little adverse effect on an adherend is particularly preferable.
Examples of the hydroxyl group-containing monomer include hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate. Among them, 2-hydroxyethyl (meth) acrylate or 4-hydroxybutyl (meth) acrylate is preferable from the viewpoint of reactivity of the hydroxyl group in the obtained (meth) acrylate polymer (a) with the crosslinking agent (B) and copolymerizability with other monomers. These may be used alone or in combination of two or more.
Examples of the carboxyl group-containing monomer include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. Among these, acrylic acid is preferable from the viewpoint of reactivity of the carboxyl group in the obtained (meth) acrylate polymer (a) with the crosslinking agent (B) and copolymerizability with other monomers. These may be used alone or in combination of two or more.
Examples of the amino group-containing monomer include aminoethyl (meth) acrylate, n-butylaminoethyl (meth) acrylate, and the like. These may be used alone or in combination of two or more.
When the (meth) acrylate polymer (a) contains a hydroxyl group-containing monomer as a monomer unit constituting the polymer, the lower limit of the content thereof is preferably 3% by mass or more, particularly preferably 10% by mass or more, and more preferably 15% by mass or more. The upper limit of the content is preferably 35% by mass or less, 3 is particularly preferably 0% by mass or less, and more preferably 25% by mass or less. When the (meth) acrylate polymer (a) contains the hydroxyl group-containing monomer as a monomer unit in the above amount, a predetermined amount of hydroxyl groups remain in the obtained adhesive. When a hydroxyl group is a hydrophilic group and a predetermined amount of the hydrophilic group is present in the adhesive, the adhesive has good compatibility with moisture impregnated into the adhesive under high-temperature and high-humidity conditions even when the adhesive is left under high-temperature and high-humidity conditions, and as a result, whitening of the adhesive when the adhesive returns to a normal-temperature and normal-humidity state is suppressed (excellent resistance to moist-heat whitening).
When the (meth) acrylate polymer (a) contains a carboxyl group-containing monomer as a monomer unit constituting the polymer, the lower limit of the content thereof is preferably 0.5% by mass or more, more preferably 1% by mass or more, and particularly preferably 6% by mass or more. The upper limit of the content is preferably 20% by mass or less, more preferably 15% by mass or less, and particularly preferably 10% by mass or less.
In the case where the adherend is a material susceptible to adverse effects due to acids, for example, a transparent conductive film, a metal wiring, or the like, it is preferable that the carboxyl group-containing monomer is not contained in the (meth) acrylate polymer (a) as a monomer unit constituting the polymer. This can suppress corrosion of the transparent conductive film or the metal wiring, or change the resistance value of the transparent conductive film, for example.
Here, "a monomer having no carboxyl group" means a monomer having substantially no carboxyl group, and the monomer having a carboxyl group is allowed to be contained on the basis that corrosion of the transparent conductive film, the metal wiring, or the like due to the carboxyl group does not occur, in addition to the fact that the monomer having a carboxyl group is not contained at all. Specifically, the carboxyl group-containing monomer is allowed to be contained in the (meth) acrylate polymer (a) in an amount of 0.01 mass% or less, preferably 0.001 mass% or less, as a monomer unit.
The (meth) acrylate polymer (a) may contain other monomers as the monomer unit constituting the polymer, if necessary. As the other monomer, a monomer containing no reactive functional group is preferable in order not to hinder the action of the reactive functional group-containing monomer. Examples of such other monomers include alkoxyalkyl (meth) acrylates such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate, (meth) acrylic acid esters having a non-crosslinkable tertiary amino group such as N, N-dimethylaminoethyl (meth) acrylate, N-dimethylaminopropyl (meth) acrylate, and (meth) acryloylmorpholine, (meth) acrylamides, dimethylacrylamides, vinyl acetate, and styrene. These may be used alone or in combination of two or more.
The polymerization form of the (meth) acrylate polymer (a) may be a random copolymer or a block copolymer.
The lower limit of the weight average molecular weight of the (meth) acrylate polymer (a) is preferably 20 ten thousand or more, particularly preferably 30 ten thousand or more, and more preferably 40 ten thousand or more. The weight average molecular weight in the present specification is a standard polystyrene conversion value measured by a Gel Permeation Chromatography (GPC) method. When the lower limit of the weight average molecular weight of the (meth) acrylate polymer (a) is not less than the lower limit, the adhesive is more excellent in blister resistance and step following property under high temperature and high humidity conditions.
The upper limit of the weight average molecular weight of the (meth) acrylate polymer (a) is preferably 100 ten thousand or less, particularly preferably 90 ten thousand or less, and more preferably 70 ten thousand or less. When the upper limit of the weight average molecular weight of the (meth) acrylate polymer (a) is the above-mentioned or less, the step following property of the adhesive at the time of sticking is more excellent.
In the adhesive composition P, one kind of the (meth) acrylate polymer (a) may be used alone, or two or more kinds may be used in combination.
(2) Crosslinking agent (B)
The adhesive composition P preferably contains a crosslinking agent (B). The adhesive composition P contains the crosslinking agent (B) and the (meth) acrylate polymer (a) is crosslinked to form a three-dimensional network structure, so that the cohesive force of the obtained adhesive can be improved, and the blister resistance and the step following property under high-temperature and high-humidity conditions can be further improved.
The crosslinking agent (B) may react with the reactive group having the (meth) acrylate polymer (a), and examples thereof include isocyanate crosslinking agents, epoxy crosslinking agents, amine crosslinking agents, melamine crosslinking agents, aziridine crosslinking agents, diamine crosslinking agents, aldehyde crosslinking agents, oxazoline crosslinking agents, metal alkoxide crosslinking agents, metal chelate crosslinking agents, metal salt crosslinking agents, and ammonium salt crosslinking agents. When the (meth) acrylate polymer (a) contains a hydroxyl group-containing monomer as a monomer unit constituting the polymer, an isocyanate-based crosslinking agent having excellent reactivity with the hydroxyl group is preferably used. When the (meth) acrylate polymer (a) contains a carboxyl group-containing monomer as a monomer unit constituting the polymer, it is preferable to use an epoxy crosslinking agent having excellent reactivity with the carboxyl group. The crosslinking agent (B) may be used alone or in combination of two or more.
The isocyanate-based crosslinking agent contains at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate, biuret and isocyanurate compounds thereof, and adducts of ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane and castor oil as a reaction product with a low-molecular-weight active hydrogen-containing compound. Among them, trimethylolpropane-modified aromatic polyisocyanates are preferable, and trimethylolpropane-modified tolylene diisocyanate is particularly preferable from the viewpoint of reactivity with hydroxyl groups.
Examples of the epoxy-based crosslinking agent include 1, 3-bis (N, N ' -diglycidylaminomethyl) cyclohexane, N, N, N ', N ' -tetraglycidylmethylenediaminobenzene, ethylene glycol diglycidyl ether, 1, 6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidylaniline, and diglycidylamine. Among them, 1, 3-bis (N, N' -diglycidylaminomethyl) cyclohexane is preferable from the viewpoint of reactivity with a carboxyl group.
The content of the crosslinking agent (B) in the adhesive composition P is preferably 0.001 parts by mass or more, particularly preferably 0.01 parts by mass or more, and more preferably 0.02 parts by mass or more, based on 100 parts by mass of the (meth) acrylate polymer (a). The upper limit is preferably 10 parts by mass or less, particularly preferably 5 parts by mass or less, and more preferably 1 part by mass or less.
The content of the crosslinking agent (B) is preferably within the above range, whereby the cohesive force of the obtained adhesive is preferably high, and the blister resistance and the step following property under high temperature and high humidity conditions of the adhesive are improved.
(3) Various additives
Various additives generally used in acrylic adhesives, for example, silane coupling agents, antistatic agents, tackifiers, antioxidants, ultraviolet absorbers, light stabilizers, softeners, fillers, refractive index modifiers, and the like may be added to the adhesive composition P as necessary.
The adhesive composition P is a mixture of various components remaining in the adhesive agent layer as they are or in a reacted state, and components removed in a drying step or the like, for example, a polymerization solvent and a dilution solvent described below are not contained in the adhesive composition P.
Here, when the adhesive composition P contains a silane coupling agent, the adhesion of the obtained adhesive to a glass member or a plastic plate is improved. Thus, the obtained adhesive is more excellent in blister resistance and step following property under high temperature and high humidity conditions.
The silane coupling agent is preferably an organosilicon compound having at least one alkoxysilyl group in the molecule, and is excellent in compatibility with the (meth) acrylate polymer (a) and has light transmittance.
Examples of such silane coupling agents include polymerizable unsaturated group-containing silicon compounds such as vinyltrimethoxysilane, vinyltriethoxysilane and methacryloxypropyltrimethoxysilane, epoxy-containing silicon compounds such as 3-glycidoxypropyltrimethoxysilane and 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, mercapto-containing silicon compounds such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane and 3-mercaptopropyldimethoxymethylsilane, amino-containing silicon compounds such as 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane and N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, amino-containing silicon compounds such as, 3-chloropropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, or a condensate of at least one of these with an alkyl group-containing silicon compound such as methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, or ethyltrimethoxysilane. These may be used alone or in combination of two or more.
When the adhesive composition P contains a silane coupling agent, the lower limit of the content is preferably 0.01 parts by mass or more, particularly preferably 0.05 parts by mass or more, and more preferably 0.1 parts by mass or more, per 100 parts by mass of the (meth) acrylate polymer (a). The upper limit of the content is preferably 5 parts by mass or less, particularly preferably 1 part by mass or less, and more preferably 0.5 part by mass or less.
(4) Preparation of adhesive composition
The adhesive composition P can be prepared by: a (meth) acrylate polymer (a) is prepared, and a crosslinking agent (B) and additives are added to the obtained (meth) acrylate polymer (a) as needed.
The (meth) acrylate polymer (a) can be prepared by polymerizing a mixture of monomers constituting the polymer by a general radical polymerization method. The polymerization of the (meth) acrylate polymer (a) is preferably carried out by a solution polymerization method using a polymerization initiator as necessary. Examples of the polymerization solvent include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone, and the like, and two or more kinds may be used in combination.
The polymerization initiator may be an azo compound, an organic peroxide, or the like, and two or more of them may be used in combination. Examples of the azo compound include 2,2' -azobisisobutyronitrile, 2' -azobis (2-methylbutyronitrile), 1' -azobis (cyclohexane 1-carbonitrile), 2' -azobis (2, 4-dimethylvaleronitrile), 2' -azobis (2, 4-dimethyl-4-methoxyvaleronitrile), dimethyl 2,2' -azobis (2-methylpropionate), 4' -azobis (4-cyanovaleric acid), 2' -azobis (2-hydroxymethylpropionitrile), and 2,2' -azobis [2- (2-imidazolin-2-yl) propane ].
Examples of the organic peroxide include benzoyl peroxide, t-butyl peroxybenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, bis (2-ethoxyethyl) peroxydicarbonate, t-butyl peroxyneodecanoate, t-butyl peroxypivalate, (3,5, 5-trimethylhexanoyl) peroxide, dipropionyl peroxide, and diacetyl peroxide.
In the polymerization step, a chain transfer agent such as 2-mercaptoethanol is added to adjust the weight average molecular weight of the obtained polymer.
When the (meth) acrylate polymer (a) is obtained, the crosslinking agent (B), the additive and the diluting solvent are added to the solution of the (meth) acrylate polymer (a) as needed, and the mixture is thoroughly mixed to obtain the adhesive composition P (coating solution) diluted with the solvent. When a solid substance is used as any one of the above-mentioned components, or when the solid substance is precipitated when the solid substance is mixed with another component in an undiluted state, the component may be dissolved or diluted in a diluting solvent alone in advance and then mixed with the other component.
Examples of the diluent solvent include aliphatic hydrocarbons such as hexane, heptane and cyclohexane, aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as methylene chloride and ethylene chloride, alcohols such as methanol, ethanol, propanol, butanol and 1-methoxy-2-propanol, ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone and cyclohexanone, esters such as ethyl acetate and butyl acetate, and cellosolve solvents such as ethyl cellosolve.
The concentration and viscosity of the coating solution prepared in this manner are not particularly limited as long as the range in which the coating can be applied, and may be appropriately selected according to the situation. For example, the concentration of the diluted adhesive composition P is 10 to 60 mass%. In addition, when obtaining a coating solution, the addition of a diluting solvent or the like is not essential, and the diluting solvent may not be added as long as the adhesive composition P has a coatable viscosity or the like. In this case, the adhesive composition P is a coating solution in which the polymerization solvent of the (meth) acrylate polymer (a) is directly used as a dilution solvent.
(5) Preparation of Adhesives
The adhesive constituting the first adhesive layer 21 and the adhesive constituting the second adhesive layer 22 can be obtained more preferably by crosslinking the adhesive composition P. The crosslinking of the adhesive composition P can be carried out by a heat treatment. The heating treatment also serves as a drying treatment for evaporating a diluent or the like from the coating film of the adhesive composition P applied to a desired object.
The heating temperature of the heating treatment is preferably 50 to 150 ℃, and particularly preferably 70 to 120 ℃. The heating time is preferably 10 seconds to 10 minutes, and particularly preferably 50 seconds to 2 minutes.
After the heat treatment, the curing period may be set to about 1 to 2 weeks at normal temperature (e.g., 23 ℃ C., 50% RH) as necessary. When the curing period is required, an adhesive is formed after the curing period has elapsed, and when the curing period is not required, an adhesive is formed after the heat treatment is ended.
When the (meth) acrylic ester polymer (a) contains the crosslinking agent (B) by the heat treatment (and curing), the (meth) acrylic ester polymer (a) is sufficiently crosslinked through the crosslinking agent (B).
(6) Gel fraction
The lower limit of the gel fraction of the adhesive constituting the first adhesive layer 21 and the adhesive constituting the second adhesive layer 22 is preferably 50% or more, particularly preferably 60% or more, and more preferably 65% or more. When the gel fraction of the adhesive is 50% or more, the cohesive force of the adhesive increases, and the blister resistance and the step following property under high temperature and high humidity of the adhesive layer 2 are further improved. The upper limit of the gel fraction of the adhesive is preferably 85% or less, particularly preferably 80% or less, and more preferably 75% or less. When the gel fraction of the adhesive is 85% or less, the adhesive does not become too hard, and the adhesive layer is more excellent in step following property. Here, the method of measuring the gel fraction of the adhesive is shown in the test examples described later.
(7) Adhesive force
The lower limit of the adhesive force of (the laminate of (the) the first adhesive agent layer 21 and (the laminate of) the second adhesive agent layer 22 to (the substrate) the soda-lime glass is preferably 5N/25mm or more, particularly preferably 10N/25mm or more, and further preferably 15N/25mm or more. When the adhesion is not less than the lower limit, the blister resistance and the step following property under high temperature and high humidity conditions are more excellent. The upper limit of the above-mentioned adhesive force is preferably 50N/25mm or less, particularly preferably 40N/25mm or less, and more preferably 35N/25mm or less. When the adhesive force is not more than the upper limit, good reworkability can be obtained, and when a bonding error occurs, an expensive display member component can be reused.
Here, the adhesive force in the present specification basically means that the adhesive force is obtained by the method according to JIS Z0237: 2009, the adhesive strength measured by the 180 degree peel method, wherein a sample for measurement is 25mm wide and 100mm long, and the sample for measurement is attached to an adherend, pressurized at 0.5MPa and 50 ℃ for 20 minutes, left to stand under conditions of normal pressure, 23 ℃ and 50% RH for 24 hours, and then measured at a peel speed of 300 mm/min. As the substrate, a polyethylene terephthalate film having a thickness of 100 μm was used.
(8) Step following rate
The lower limit value of the step following ratio (%) of the first adhesive agent layer 21 and the second adhesive agent layer 22 represented by the following formula is preferably 10% or more, particularly preferably 15% or more, and more preferably 20% or more. The upper limit value of the level difference following rate (%) is preferably 50% or less, particularly preferably 45% or less, and more preferably 40% or less.
The step following ratio (%) { (height of step (μm) which remains in a filled state without air bubbles, floating, peeling, or the like after the durability test is defined))/(thickness of adhesive layer) } × 100
The test method of the stepped portion following ratio is shown in test examples described later.
The step following ratio of the first adhesive layer 21 and the second adhesive layer 22 as the outer layers is within the above range, and thus the step following property is more excellent as the adhesive layer 2 of the adhesive sheet 1 of the present embodiment.
2. Third adhesive layer
The active energy ray-curable adhesive constituting the third adhesive layer 23 is not particularly limited as long as it satisfies the above physical properties. The active energy ray-curable adhesive preferably contains at least one of an active energy ray-curable monomer, oligomer, and polymer, or a mixture thereof, and may contain one of an active energy ray-non-curable monomer, oligomer, and polymer, or a mixture thereof.
In the present embodiment, the active energy ray-curable adhesive constituting the third adhesive layer 23 is preferably obtained from an adhesive composition Q containing a (meth) acrylate polymer (C) and an active energy ray-curable compound (D). The adhesive composition Q further preferably contains a crosslinking agent (B), and in this case, the active energy ray-curable adhesive can be obtained by crosslinking the adhesive composition Q.
(1) (meth) acrylate ester Polymer (C)
The (meth) acrylate polymer (C) is basically the same as the (meth) acrylate polymer (a) as long as the active energy ray-curable adhesive constituting the third adhesive layer 23 satisfies the physical properties described above. However, since the third adhesive agent layer 23 is an intermediate layer and does not come into direct contact with an adherend, the (meth) acrylate polymer (C) preferably further contains a carboxyl group-containing monomer as a monomer unit constituting the polymer.
The (meth) acrylate polymer (C) preferably further contains a nitrogen atom-containing monomer as a monomer unit constituting the polymer. The presence of the nitrogen atom-containing monomer as a constituent unit in the polymer can promote the crosslinking reaction between the reactive functional group of the (meth) acrylate polymer (C) and the crosslinking agent (B). Examples of the nitrogen atom-containing monomer include a monomer having an amino group, a monomer having an amide group, and a monomer having a nitrogen-containing heterocycle, and among these, a monomer having a nitrogen-containing heterocycle is preferable from the viewpoint of imparting appropriate rigidity to the (meth) acrylate polymer (C).
Examples of the monomer having a nitrogen-containing heterocycle include N- (meth) acryloylmorpholine, N-vinyl-2-pyrrolidone, N- (meth) acryloylpyrrolidone, N- (meth) acryloylpiperidine, N- (meth) acryloylpyrrolidine, N- (meth) acryloylaziridine, aziridinylethyl (meth) acrylate, 2-vinylpyridine, 4-vinylpyridine, 2-vinylpyrazine, 1-vinylimidazole, N-vinylcarbazole, and N-vinylphthalimide, and among them, N- (meth) acryloylmorpholine which exhibits more excellent adhesion is preferable, and N-acryloylmorpholine is particularly preferable.
Further, examples of the nitrogen atom-containing monomer include (meth) acrylamide, N-methyl (meth) acrylamide, N-methylol (meth) acrylamide, N-t-butyl (meth) acrylamide, N-dimethyl (meth) acrylamide, N-ethyl (meth) acrylamide, N, n-dimethylaminopropyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-phenyl (meth) acrylamide, dimethylaminopropyl (meth) acrylamide, N-vinylcaprolactam, monomethylaminoethyl (meth) acrylate, monoethylaminoethyl (meth) acrylate, monomethylaminopropyl (meth) acrylate, monoethylaminopropyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, and the like.
The nitrogen atom-containing monomer may be used alone or in combination of two or more.
When the (meth) acrylate polymer (C) contains a nitrogen atom-containing monomer as a monomer unit constituting the polymer, the content of the nitrogen atom-containing monomer is preferably 1% by mass or more, particularly preferably 2% by mass or more, and more preferably 3% by mass or more. The (meth) acrylate polymer (a) preferably contains the nitrogen atom-containing monomer in an amount of 20 mass% or less as a monomer unit constituting the polymer, and particularly preferably contains 15 mass% or less, and more preferably contains 10 mass% or less. When the content of the nitrogen atom-containing monomer is within the above range, the effect of promoting the crosslinking reaction between the (meth) acrylate polymer (C) and the crosslinking agent (B) can be obtained favorably.
(2) Active energy ray-curable compound (D)
When the adhesive composition Q contains the active energy ray-curable compound (D), the active energy ray-curable compound (D) is polymerized with each other when the active energy ray-curable adhesive is cured by irradiation with active energy rays, and the active energy ray-curable adhesive is formed by thermally crosslinking the adhesive composition Q, and therefore, it is presumed that the polymerized active energy ray-curable compound (D) is entangled into a crosslinked structure (three-dimensional network structure) of the (meth) acrylate polymer (a). The adhesive having the above-described high-order structure has a high cohesive force and exhibits a relatively high elastic modulus, and therefore the adhesive layer 2 having the third adhesive layer 23 as an intermediate layer is more excellent in blister resistance.
The active energy ray-curable compound (D) is cured by irradiation with an active energy ray, and is not particularly limited as long as the above-described effects can be obtained, and may be any of a monomer, an oligomer, or a polymer, or a mixture thereof. Among them, preferred is a polyfunctional acrylate monomer having excellent compatibility with the (meth) acrylate polymer (C) and the like and a molecular weight of less than 1000.
Examples of the polyfunctional acrylate monomer having a molecular weight of less than 1000 include 1, 4-butanediol di (meth) acrylate, 1, 6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, neopentyl glycol adipate di (meth) acrylate, hydroxypivalic acid neopentyl glycol di (meth) acrylate, dicyclopentanyl di (meth) acrylate, 2-functional types such as caprolactone-modified dicyclopentyl di (meth) acrylate, ethylene oxide-modified phosphoric acid di (meth) acrylate, di (acryloyloxyethyl) isocyanurate, allylated cyclohexyl di (meth) acrylate, ethoxylated bisphenol a diacrylate, and 9, 9-bis [4- (2-acryloyloxyethoxy) phenyl ] fluorene; 3-functional types such as trimethylolpropane tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, propionic acid-modified dipentaerythritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, propylene oxide-modified trimethylolpropane tri (meth) acrylate, tris (acryloyloxyethyl) isocyanurate, and e-caprolactone-modified tris- (2- (meth) acryloyloxyethyl) isocyanurate; 4-functional types such as diglycerin tetra (meth) acrylate and pentaerythritol tetra (meth) acrylate; 5-functional types such as propionic acid-modified dipentaerythritol penta (meth) acrylate; 6-functional types such as dipentaerythritol hexa (meth) acrylate and caprolactone-modified dipentaerythritol hexa (meth) acrylate. Among the above, pentaerythritol tri (meth) acrylate and epsilon-caprolactone-modified tris- (2- (meth) acryloyloxyethyl) isocyanurate are preferable from the viewpoint of the blister resistance of the obtained adhesive agent layer. These may be used alone or in combination of two or more.
As the active energy ray-curable compound (D), an active energy ray-curable acrylate oligomer can also be used. The acrylate oligomer preferably has a weight average molecular weight of 50,000 or less. Examples of such acrylate oligomers include polyester acrylates, epoxy acrylates, urethane acrylates, polyether acrylates, polybutadiene acrylates, and silicone acrylates.
The upper limit of the weight average molecular weight of the acrylate oligomer is preferably 50,000 or less, and particularly preferably 40,000 or less. The lower limit of the weight average molecular weight is preferably 500 or more, and particularly preferably 3,000 or more. These acrylate oligomers may be used alone or in combination of two or more.
Further, as the active energy ray-curable compound (D), an addition acrylate polymer having a group having a (meth) acryloyl group introduced into a side chain thereof may be used. Such an addition acrylate polymer can be obtained by using a copolymer of a (meth) acrylate and a monomer having a crosslinkable functional group in the molecule, and reacting a part of the crosslinkable functional group of the copolymer with a compound having a group capable of reacting with a (meth) acryloyl group and the crosslinkable functional group.
The lower limit of the weight average molecular weight of the addition acrylate polymer is preferably 5 ten thousand or more, and particularly preferably 10 ten thousand or more. The upper limit of the weight average molecular weight is preferably 90 ten thousand or less, and particularly preferably 50 ten thousand or less.
The active energy ray-curable compound (D) may be used alone or in combination with two or more of the above multifunctional acrylate monomer, acrylate oligomer and addition acrylate polymer, or may be used in combination with other active energy ray-curable components.
The content of the active energy ray-curable compound (D) in the adhesive composition Q is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, and particularly preferably 3.0 parts by mass or more, per 100 parts by mass of the (meth) acrylate polymer (C), from the viewpoint of improving the cohesive force of the adhesive obtained and of being excellent in blister resistance. On the other hand, the upper limit of the content is preferably 50 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 12 parts by mass or less, from the viewpoint of preventing phase separation between the active energy ray-curable compound (D) and the (meth) acrylate polymer (C).
(3) Crosslinking agent (B)
The adhesive composition Q preferably contains a crosslinking agent (B). The adhesive composition Q contains the crosslinking agent (B), and thus the (meth) acrylate polymer (C) can be crosslinked to form a three-dimensional network structure, and the cohesive force of the obtained adhesive is improved, and further the blister resistance and the step following property under high-temperature and high-humidity conditions are improved. As the crosslinking agent (B), the same crosslinking agent as described for the adhesive composition P can be used, and the amount used is also the same.
(4) Photopolymerization initiator (E)
When ultraviolet rays are used as the active energy rays to be irradiated when curing the active energy ray-curable adhesive constituting the third adhesive layer 23, the adhesive composition Q preferably further contains a photopolymerization initiator (E). By containing the photopolymerization initiator (E) in this manner, the active energy ray-curable compound (D) can be efficiently polymerized, and the polymerization curing time and the irradiation dose of the active energy ray can be reduced.
Examples of such photopolymerization initiators (E) include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2-dimethoxy-2-phenylacetophenone, 2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexylphenylketone, 2-methyl-1- [4- (methylthio) phenyl ] -2-morpholino-propan-1-one, 4- (2-hydroxyethoxy) phenyl-2- (hydroxy-2-propyl) one, benzophenone, and acetophenone, P-phenylbenzophenone, 4' -diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2, 4-dimethylthioxanthone, 2, 4-diethylthioxanthone, benzyldimethylketal, acetophenone dimethylketal, p-dimethylaminobenzoate, oligo [ 2-hydroxy-2-methyl-1 [4- (1-methylvinyl) phenyl ] acetone ], 2,4, 6-trimethylbenzoyl-diphenyl-phosphine oxide, and the like. These may be used alone or in combination of two or more.
The lower limit of the content of the photopolymerization initiator (E) in the adhesive composition Q is preferably 0.1 part by mass or more, and particularly preferably 1 part by mass or more, per 100 parts by mass of the active energy ray-curable compound (D). The upper limit is preferably 30 parts by mass or less, and particularly preferably 10 parts by mass or less.
(5) Various additives
Various additives generally used in acrylic adhesives, for example, silane coupling agents, antistatic agents, tackifiers, antioxidants, ultraviolet absorbers, light stabilizers, softeners, fillers, refractive index modifiers, and the like can be added to the adhesive composition Q as needed.
The adhesive composition Q is a mixture of various components remaining in the adhesive agent layer as they are or in a state of undergoing a reaction, and the adhesive composition Q does not include a component removed in a drying step or the like, for example, a polymerization solvent or a diluting solvent described later.
(6) Preparation of adhesive composition
The adhesive composition Q can be prepared by: the (meth) acrylate polymer (C) is prepared, and the obtained (meth) acrylate polymer (C) and the active energy ray-curable compound (D) are mixed, and if necessary, a crosslinking agent (B), a photopolymerization initiator (E), and additives are added. Specifically, it can be prepared by the same method as the method for preparing the adhesive composition P.
(7) Preparation of Adhesives
The active energy ray-curable adhesive constituting the third adhesive layer 23 can be preferably obtained by crosslinking (thermal crosslinking) the adhesive composition Q. The crosslinking of the adhesive composition Q can be performed by the same method as the crosslinking method of the adhesive composition P.
(8) Gel fraction
The lower limit of the gel fraction before curing of the active energy ray-curable adhesive constituting the third adhesive layer 23 is preferably 40% or more, particularly preferably 45% or more, and more preferably 50% or more. When the gel fraction before curing is 40% or more, the cohesive force of the active energy ray-curable adhesive increases, and the processability of the adhesive layer 2 becomes further excellent. The upper limit of the gel fraction before curing is preferably 75% or less, particularly preferably 70% or less, and more preferably 65% or less. When the gel fraction before curing is 75% or less, the active energy ray-curable adhesive does not become too hard, and the adhesive layer 2 is further excellent in initial step following property.
The lower limit of the gel fraction after curing (after curing by irradiation with active energy rays) of the active energy ray-curable adhesive constituting the third adhesive layer 23 is preferably 70% or more, particularly preferably 75% or more, and more preferably 79% or more. When the gel fraction after curing is 70% or more, the cohesive force increases, and the adhesive agent layer is more excellent in blister resistance and step following property under high temperature and high humidity. The upper limit of the gel fraction after curing is preferably 95% or less, particularly preferably 92% or less, and more preferably 90% or less. When the gel fraction after curing is 95% or less, the adhesive layer has excellent adhesiveness to the adjacent first adhesive agent layer 21 and second adhesive agent layer 22, and thus the adhesive layer has more excellent blister resistance and step following property under high temperature and high humidity. Here, the method of measuring the gel portion of the active energy ray-curable adhesive is as shown in test examples described later.
(9) Adhesive force
The lower limit of the adhesion force to soda-lime glass before curing (of the laminate with the substrate) of the active energy ray-curable adhesive constituting the third adhesive layer 23 is preferably 20N/25mm or more, particularly preferably 25N/25mm or more, and more preferably 30N/25mm or more. When the adhesion before curing is not less than the lower limit, adhesion to the first adhesive layer 21 and the second adhesive layer 22 is increased, and interlayer peeling in the adhesive layer 2 can be suppressed. The upper limit of the above-mentioned adhesive force is not particularly limited, but is preferably 50N/25mm or less in general, and 45N/25mm or less in particular.
The lower limit value of the adhesion to soda-lime glass after curing (after curing by irradiation with active energy rays) of (the laminate with a substrate of) the active energy ray-curable adhesive constituting the third adhesive layer 23 is preferably 20N/25mm or more, particularly preferably 25N/25mm or more, and further preferably 30N/25mm or more. When the cured adhesive force is not less than the lower limit, the adhesiveness to the first adhesive agent layer 21 and the second adhesive agent layer 22 is increased, and the durability of the obtained product (display) is high. The upper limit of the above-mentioned adhesive force is not particularly limited, but is usually preferably 55N/25mm or less, and particularly preferably 50N/25mm or less.
(10) Step following rate
The lower limit value of the step following ratio (%) after curing (after curing by irradiation with active energy rays) of the third adhesive agent layer 23 is preferably 30% or more, particularly preferably 35% or more, and more preferably 40% or more. The upper limit value of the level difference following ratio (%) is preferably 65% or less, particularly preferably 60% or less, and more preferably 55% or less.
The step following ratio of the third adhesive layer 23 as an intermediate layer is within the above range, and thus the adhesive layer 2 as the adhesive sheet 1 of the present embodiment is more excellent in step following property.
3. Release sheet
The release sheets 31 and 32 protect the adhesive layer 2 before the adhesive sheet 1 is used, and are released when the adhesive sheet 1 (adhesive layer 2) is used. In the adhesive sheet 1 of the present embodiment, one or both of the release sheets 31 and 32 are not necessarily required.
Examples of the release sheets 31 and 32 include a polyethylene film, a polypropylene film, a polybutylene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, a vinyl chloride copolymer film, a polyethylene terephthalate film, a polyethylene naphthalate film, a polybutylene terephthalate film, a urethane film, an ethylene-vinyl acetate film, an ionomer resin film, an ethylene- (meth) acrylic acid copolymer film, an ethylene- (meth) acrylic acid ester copolymer film, a polystyrene film, a polycarbonate film, a polyimide film, and a fluororesin film. Also, a crosslinked film of these films may be used. Further, a laminated film of these films may be used.
The release surfaces (particularly, surfaces in contact with the adhesive layer 2) of the release sheets 31 and 32 are preferably subjected to a release treatment. Examples of the release agent used in the release treatment include alkyd based, silicone based, fluorine based, unsaturated polyester based, polyolefin based, and wax based release agents. Of the release sheets 31 and 32, one release sheet is preferably a heavy release type release sheet having a large release force, and the other release sheet is preferably a light release type release sheet having a small release force.
The thickness of the release sheets 31 and 32 is not particularly limited, but is usually about 20 to 150 μm.
4. Physical Properties of adhesive sheet
(1) Step following rate
The lower limit value of the step following ratio (%) after curing (after curing by irradiation with active energy rays) of the adhesive layer 2 of the adhesive sheet 1 of the present embodiment is preferably 25% or more, particularly preferably 30% or more, and more preferably 40% or more. The upper limit value of the level difference following rate (%) is preferably 60% or less, particularly preferably 55% or less, and more preferably 50% or less.
As described above, the adhesive layer 2 in the present embodiment is excellent in step following property, and therefore can realize a high step following ratio as described above. Thus, the adhesive layer 2 favorably follows the level difference of the display constituent member, and even after the durability test, the occurrence of bubbles, floating, peeling, and the like in the vicinity of the level difference can be suppressed, whereby the occurrence of reflection loss of light can be suppressed.
(2) 100% modulus
The lower limit of the 100% modulus of the adhesive layer 2 of the adhesive sheet 1 of the present embodiment before curing (before curing by irradiation with active energy rays) is preferably 40kPa or more, particularly preferably 50kPa or more, and more preferably 60kPa or more. The lower limit of the 100% modulus is not less than the lower limit, and thus the processability of the adhesive layer 2 is further improved. The upper limit of the 100% modulus of the adhesive layer 2 before curing is preferably 200kPa or less, particularly preferably 150kPa or less, and more preferably 90kPa or less. The upper limit of the 100% modulus is not more than the upper limit, and thus the adhesive layer 2 is more excellent in initial level difference following property.
The lower limit of the 100% modulus after curing (after curing by irradiation with active energy rays) of the adhesive layer 2 of the adhesive sheet 1 of the present embodiment is preferably 70kPa or more, particularly preferably 80kPa or more, and more preferably 125kPa or more. The lower limit of the 100% modulus is not less than the lower limit, and thus the adhesive agent layer 2 is more excellent in blister resistance and step following property under high temperature and high humidity. The upper limit of the 100% modulus of the adhesive layer 2 before curing is preferably 200kPa or less, particularly preferably 170kPa or less, and more preferably 150kPa or less. The upper limit of the 100% modulus is not more than the upper limit, and thus the adhesiveness (adhesive force) of the adhesive layer 2 to an adherend (display body member) can be easily maintained high.
5. Preparation of adhesive sheet
As an example of the production of the adhesive sheet 1, a coating solution of the above-mentioned adhesive composition P is applied to the release surface of one release sheet 31, and heat treatment is performed to thermally crosslink the adhesive composition P and form a coating layer, thereby obtaining a release sheet 31 with a coating layer of the adhesive composition P. Further, the coating liquid of the adhesive composition P is applied to the release surface of the other release sheet 32, and heat treatment is performed to thermally crosslink the adhesive composition P to form a coating layer, thereby obtaining a release sheet 32 with a coating layer of the adhesive composition P. Then, the coating solution of the adhesive composition Q is applied to the release surface of the other release sheet, and heat treatment is performed to thermally crosslink the adhesive composition Q to form a coating layer, thereby obtaining a release sheet with a coating layer of the adhesive composition Q.
Thereafter, the release sheet 31 with the coating layer of the adhesive composition P and the release sheet with the coating layer of the adhesive composition Q are bonded so that the two coating layers are in contact with each other, and the release sheet is released from the coating layer of the adhesive composition Q. Next, the coating layer of the adhesive composition Q and the release sheet 32 with the coating layer of the adhesive composition P are bonded to each other so that the two coating layers are in contact with each other. When the curing period is required, or when the curing period is not required after the curing period, the first adhesive layer 21 may be formed by the coating layer of one of the laminated adhesive compositions P, the third adhesive layer 23 may be formed by the coating layer of the adhesive composition Q, and the second adhesive layer 22 may be formed by the coating layer of the other adhesive composition P. This provides an adhesive sheet 1, in which the adhesive sheet 1 is obtained by sandwiching the adhesive layer 2 composed of the first adhesive layer 21, the third adhesive layer 23, and the second adhesive layer 22 between the release sheet 31 and the release sheet 32. The curing of the coating layer of the adhesive composition may be performed after the coating layer of the adhesive composition is bonded to form 3 layers as described above, or may be performed before the bonding.
Examples of the method of applying the coating liquid of the adhesive composition P include a bar coating method, a blade coating method, a roll coating method, a blade coating method, a die coating method, and a gravure coating method.
Since the adhesive sheet 1 of the present embodiment has good workability, when the adhesive sheet 1 is subjected to punching, problems such as the adhesive overflowing from the cut surface and adhering to the blade edge can be suppressed.
[ display body ]
As shown in fig. 2, the display body 4 of the present embodiment includes the following components: a first display body constituting member 51 (one display body constituting member) having a step difference at least on the surface on the bonded side; a second display body constituting member 52 (another display body constituting member); and an adhesive layer 2 which is located between the first display element constituting member 51 and the second display element constituting member 52 and bonds them to each other. In the display 4 of the present embodiment, the first display component member 51 has a step on the surface on the adhesive agent layer 2 side, specifically, a step formed by the printed layer 6.
The adhesive layer 2 in the above-mentioned display 4 is one in which the adhesive layer 2 (particularly the third adhesive layer 23) of the above-mentioned adhesive sheet 1 is cured by irradiation with an active energy ray (for convenience, the same name and symbol are used). Here, the active energy ray refers to a ray having an energy quantum in an electromagnetic wave or a charged particle beam, and specifically includes an ultraviolet ray, an electron beam, and the like. Among the active energy rays, ultraviolet rays which are easy to handle are particularly preferable.
The ultraviolet irradiation can be performed by a high-pressure mercury lamp, FUSION H lamp, xenon lamp, or the like, and the illuminance is preferably 50 to 1000mW/cm with respect to the amount of ultraviolet irradiation2Left and right. The light quantity is preferably 50 to 10000mJ/cm2More preferably 80 to 5000mJ/cm2Particularly preferably 200 to 2000mJ/cm2. On the other hand, the irradiation of the electron beam can be performed by an electron beam accelerator or the like, and the irradiation amount of the electron beam is preferably about 10 to 1000 krad.
The irradiation of the active energy ray with respect to the adhesive agent layer 2 is preferably performed with the adhesive agent layer 2 so that the first display element constituting member 51 and the second display element constituting member 52 are bonded to each other, and then the active energy ray is transmitted through the first display element constituting member 51 and the second display element constituting member 52.
When the adhesive agent layer 2 is irradiated with an active energy ray, the active energy ray-curable compound (D) in the third adhesive agent layer 23 is polymerized and cured. The adhesive agent layer 2 obtained by curing the third adhesive agent layer 23 (in particular, curing the third adhesive agent layer) by irradiation with an active energy ray is excellent in blister resistance and step following property under high temperature and high humidity.
Examples of the display 4 include a Liquid Crystal Display (LCD) display, a Light Emitting Diode (LED) display, an organic electroluminescence (organic EL) display, and an electronic paper, and may be a touch panel. The display 4 may be a member constituting a part of the display.
The first display element constituting member 51 may be a glass plate, a plastic plate, or the like, and is preferably a protective panel made of a laminate or the like including these. They are typically hard bodies. In this case, the printed layer 6 is generally formed in a frame shape on the adhesive layer 2 side of the first display element constituting member 51.
The glass plate is not particularly limited, and examples thereof include chemically strengthened glass, alkali-free glass, quartz glass, soda-lime glass, barium-strontium-containing glass, aluminosilicate glass, lead glass, borosilicate glass, barium borosilicate glass, and the like. The thickness of the glass plate is not particularly limited, but is usually 0.1 to 5mm, preferably 0.2 to 2 mm.
The plastic plate is not particularly limited, and examples thereof include an acrylic plate and a polycarbonate plate. The thickness of the plastic sheet is not particularly limited, but is usually 0.2 to 5mm, preferably 0.4 to 3 mm.
Further, various functional layers (a transparent conductive film, a metal layer, a silicon oxide layer, a hard coat layer, an antiglare layer, etc.) may be provided on one surface or both surfaces of the glass plate or the plastic plate, and an optical member may be laminated. Also, the transparent conductive film and the metal layer may be patterned.
The second display body constituting member 52 is preferably an optical member to be attached to the first display body constituting member 51, a display body module (for example, a Liquid Crystal (LCD) module, a Light Emitting Diode (LED) module, an organic electroluminescence (organic EL) module, or the like), an optical member as a part of the display body module, or a laminated body including the display body module.
Examples of the optical member include a scattering prevention film, a polarizing plate (polarizing film), a polarizing mirror, a retardation plate (retardation film), a viewing angle compensation film, a brightness enhancement film, a contrast enhancement film, a liquid crystal polymer film, a diffusion film, a semi-transmissive reflective film, and a transparent conductive film. Examples of the scattering prevention film include a hard coat film in which a hard coat layer is formed on one surface of a base film.
The material constituting the printed layer 6 is not particularly limited, and a known material for printing can be used. The lower limit of the thickness of the printed layer 6, that is, the step height is preferably 3 μm or more, more preferably 5 μm or more, particularly preferably 7 μm or more, and most preferably 10 μm or more. The lower limit value is not less than the lower limit value, so that the concealing property of the electric wiring and the like from the observer side can be sufficiently ensured. The upper limit is preferably 50 μm or less, more preferably 35 μm or less, particularly preferably 25 μm or less, and further preferably 20 μm or less. The upper limit value is not more than the upper limit value, whereby deterioration of the step following property of the adhesive layer 2 to the printed layer 6 can be prevented.
In the preparation of the display 4, one release sheet 31 of the adhesive sheet 1 is peeled off, and the exposed adhesive layer 2 of the adhesive sheet 1 is bonded to the surface of the first display constituting member 51 on the side where the printed layer 6 is present, as an example. In this case, since the adhesive layer 2 has excellent step following properties, generation of a gap or floating in the vicinity of the step formed by the printed layer 6 can be suppressed.
Thereafter, the other release sheet 32 is peeled from the adhesive layer 2 of the adhesive sheet 1, and the exposed adhesive layer 2 of the adhesive sheet 1 and the second display constituent member 52 are bonded. As another example, the order of bonding the first display body constituting member 51 and the second display body constituting member 52 may be replaced.
In the display 4, the adhesive layer 2 has excellent blister resistance, and therefore even when the display 4 is left to stand under high-temperature and high-humidity conditions (for example, 85 ℃, 85% RH, 72 hours) and outgassing occurs from a display constituent member made of a plastic plate or the like, blistering phenomena such as blistering, floating, peeling, and the like are suppressed from occurring on the surfaces of the adhesive layer 2, the display constituent member 51, and the display constituent member 52.
In the display 4, since the adhesive agent layer 2 has excellent step followability even under high-temperature and high-humidity conditions, bubbles, floating, peeling, and the like can be suppressed from occurring in the vicinity of the step even when the display 4 is left under high-temperature and high-humidity conditions (for example, 85 ℃, 85% RH, 72 hours).
The above-described embodiments are described for the convenience of understanding the present invention, and are not described for the purpose of limiting the present invention. Therefore, each element disclosed in the above embodiments is also intended to include all design modifications and equivalents that fall within the technical scope of the present invention.
For example, one or both of the release sheet 31 and the release sheet 32 in the adhesive sheet 1 may be omitted, and a desired optical member may be laminated instead of the release sheet 31 and/or the release sheet 32. Further, another layer may be present between the first adhesive layer 21 and/or the second adhesive layer 22 and the third adhesive layer 23 in the adhesive layer 2, or another layer may be present on the outer side (the side of the release sheet 31, 32) of the first adhesive layer 21 and/or the second adhesive layer 22 in the adhesive layer 2.
The first display body constituting member 51 may have a step other than the printed layer 6. Further, not only the first display element constituting member 51 but also the second display element constituting member 52 may have a step on the adhesive agent layer 2 side.
Examples
The present invention will be described in more detail with reference to examples and the like, but the scope of the present invention is not limited to these examples and the like.
[ preparation example 1]
Preparation of a laminate having a first adhesive layer or a second adhesive layer
(1) Preparation of (meth) acrylate Polymer (A)
The (meth) acrylate polymer (a) was prepared by copolymerizing 60 parts by mass of 2-ethylhexyl acrylate, 20 parts by mass of methyl methacrylate, and 20 parts by mass of 2-hydroxyethyl acrylate. The molecular weight of the (meth) acrylate polymer (a) was measured by the method described later, and the weight average molecular weight (Mw) was 60 ten thousand.
(2) Preparation of adhesive composition P
100 parts by mass (solid content equivalent; the same applies hereinafter) of the (meth) acrylate polymer (A) obtained in the step (1), 0.25 part by mass of trimethylolpropane-modified tolylene diisocyanate (product name "Coronate L", manufactured by Nippon Polyurethane Industry Co., Ltd.) as the crosslinking agent (B), and 0.30 part by mass of 3-glycidoxypropyltrimethoxysilane (Shin-Etsu Chemical Co., Ltd., product name "KBM 403", manufactured by Ltd.) as the silane coupling agent were mixed and sufficiently stirred, and diluted with methyl ethyl ketone, thereby obtaining a coating solution of the adhesive composition P having a solid content concentration of 35 mass%.
Here, the respective additions (solid content equivalent values) of the adhesive composition when the (meth) acrylate polymer is assumed to be 100 parts by mass (solid content equivalent values) are shown in table 1. The abbreviations and the like described in table 1 are as follows.
[ (meth) acrylate Polymer ]
2 EHA: 2-ethylhexyl acrylate
MMA: methacrylic acid methyl ester
HEA: 2-Hydroxyethyl acrylate
BA: acrylic acid n-butyl ester
IBXMA: isobornyl methacrylate
IBXA: acrylic acid isobornyl ester
ACMO: 4-acryloyl morpholine
AA: acrylic acid
[ crosslinking agent ]
TDI compounds: trimethylolpropane modified toluene diisocyanate (product name "Coronate L", manufactured by Nippon Polyurethane Industry Co., Ltd.)
Epoxy resin: 1, 3-bis (N, N' -diglycidylaminomethyl) cyclohexane (MITSUBISHI GAS CHEMICAL COMPANY, manufactured by INC., product name "TETRAD C-5")
(3) Production of laminate
The coating solution of the adhesive composition P obtained in the above step (2) was applied to a release-treated surface of a heavy release type release sheet (manufactured by linetec Corporation, product name "SP-PET 752150") formed by release-treating one surface of a polyethylene terephthalate film with a silicone-based release agent, and then heat-treated at 90 ℃ for 1 minute to form a coating layer (thickness: 25 μm). Similarly, the coating solution of the adhesive composition obtained in the above step 2 was applied to the release-treated surface of a light release type release sheet (manufactured by Lintec Corporation, product name "SP-PET 382120") formed by release-treating one surface of a polyethylene terephthalate film with a silicone type release agent, and then heat-treated at 90 ℃ for 1 minute to form a coating layer (thickness: 25 μm).
Next, the heavy release sheet having the coating layer obtained in the above and the light release sheet having the coating layer obtained in the above were bonded to each other so that the two coating layers were in contact with each other, and cured at 23 ℃ and 50% RH for 7 days, thereby producing a laminate having the following structure, i.e., a heavy release sheet/adhesive layer (thickness: 50 μm)/light release sheet. The adhesive layer is composed of an active energy ray non-curable adhesive and corresponds to the first adhesive layer and the second adhesive layer.
The thickness of the adhesive layer was a value measured according to JIS K7130 using a constant pressure thickness measuring instrument (manufactured by TECCLOCK Corporation, product name "PG-02").
[ preparation examples 2 to 3]
As shown in table 1, a laminate was produced in the same manner as in production example 1 except that the kinds and proportions of the respective monomers constituting the (meth) acrylate polymer (a) and the weight average molecular weight of the (meth) acrylate polymer (a) were changed.
[ preparation example 4]
Preparation of a laminate having a third adhesive layer
(1) Preparation of (meth) acrylate Polymer (C)
The (meth) acrylate polymer (C) was prepared by copolymerizing 60 parts by mass of 2-ethylhexyl acrylate, 10 parts by mass of isobornyl acrylate, 10 parts by mass of 4-acryloylmorpholine, and 20 parts by mass of 2-hydroxyethyl acrylate. The weight average molecular weight (Mw) of the (meth) acrylate polymer (C) was measured by the method described later, and was 50 ten thousand.
(2) Preparation of adhesive composition Q
A coating solution of an adhesive composition Q having a solid content of 48 mass% was obtained by mixing and sufficiently stirring the following components and diluting the mixture with methyl ethyl ketone, namely 100 parts by mass of the (meth) acrylate polymer (C) obtained in the above step (1), 5.0 parts by mass of epsilon-caprolactone-modified tris- (2-acryloyloxyethyl) isocyanurate (Shin-Nakamura Chemical Co., Ltd., product name "NK ester A-9300-1 CL", manufactured by Ltd.) as the active energy ray-curable compound (D), 0.50 parts by mass of benzophenone and 1-hydroxycyclohexyl phenyl ketone mixed at a mass ratio of 1:1 as the photopolymerization initiator (E) (product name "Irgacure 500", manufactured by BASF Co., Ltd.), and 0.50 parts by mass of trimethylolpropane-modified toluene diisocyanate (Nippon Polyurethane Co., Industry Co., B) as the crosslinking agent (B), 0.25 part by mass of 3-glycidoxypropyltrimethoxysilane (Shin-Etsu Chemical Co., Ltd., product name "KBM-403" manufactured by Ltd.) as a silane coupling agent.
(3) Production of laminate
Using the coating solution of the adhesive composition Q obtained in the step (2), a laminate having a structure of a heavy release sheet/an adhesive layer (thickness: 50 μm)/a light release sheet was produced in the same manner as the adhesive composition P. The adhesive layer is made of an active energy ray-curable adhesive and corresponds to the third adhesive layer.
[ preparation example 5 ]
A laminate was produced in the same manner as in production example 4, except that the kind and ratio of each monomer constituting the (meth) acrylate polymer (a), the weight average molecular weight of the (meth) acrylate polymer (a), the ratio of the active energy ray-curable compound (D), the ratio of the photopolymerization initiator (E), and the kind and ratio of the crosslinking agent (B) were changed as shown in table 1.
Wherein the weight average molecular weight (Mw) is a polystyrene-equivalent weight average molecular weight measured by Gel Permeation Chromatography (GPC) under the following conditions (GPC measurement).
< measurement Condition >
GPC measurement apparatus: HLC-8020 (manufactured by TOSOH CORPORATION)
GPC column (passage in the following order): TOSOH CORPORATION (TOSOH CORPORATION)
TSK guard column HXL-H
TSK gel GMHXL(×2)
TSK gel G2000HXL
Determination of the solvent: tetrahydrofuran (THF)
Measurement temperature: 40 deg.C
[ example 1]
The light release type release sheet was peeled from the laminate obtained in production example 1, and the light release type release sheet was peeled from the laminate obtained in production example 4, and the exposed first adhesive layer and third adhesive layer were bonded in contact with each other, thereby peeling the heavy release type release sheet from the third adhesive layer. Next, a light-release sheet was peeled from the laminate obtained in preparation example 1, and the exposed second adhesive layer and the third adhesive layer were bonded so as to be in contact with each other to obtain an adhesive sheet in which an adhesive layer composed of the first adhesive layer, the third adhesive layer, and the second adhesive layer was sandwiched between two heavy-release sheets.
[ examples 2 to 6, comparative examples 1 to 7 ]
Adhesive layers of the laminates prepared in preparation examples 1 to 5 were laminated in the order of lamination shown in table 2, and adhesive sheets were prepared in the same manner as in example 1. Here, the thickness of each adhesive agent layer was changed so as to be the thickness shown in table 2.
[ test example 1] (measurement of gel fraction)
The laminates prepared in preparation examples 1 to 5 were cut into 80mm × 80mm sizes, the adhesive layers thereof were wrapped in a polyester net (mesh size 200), the masses thereof were weighed by a precision balance, and the masses of the nets alone were subtracted to calculate the masses of the adhesives themselves. The mass at this time was set to M1.
Subsequently, the adhesive coated on the polyester net was immersed in ethyl acetate at room temperature (23 ℃ C.) for 24 hours. Thereafter, the adhesive was taken out, and air-dried at a temperature of 23 ℃ and a relative humidity of 50% for 24 hours, and further dried in an oven at 80 ℃ for 12 hours. After drying, the mass was weighed by a precision balance and the mass of the web alone was subtracted to calculate the mass of the adhesive itself. The mass at this time was set to M2. The gel fraction (%) is represented by (M2/M1). times.100. The results are shown in Table 3.
In addition, with respect to the adhesive agent layers of the laminates of preparation examples 4 and 5, gel portions before and after irradiation of the adhesive agent layer with ultraviolet rays (irradiation from the side of the heavy-release type release sheet) were measured. In the table, the result before the ultraviolet irradiation is referred to as "before UV", and the result after the ultraviolet irradiation is referred to as "after UV" (the same applies hereinafter). The irradiation conditions of ultraviolet rays are as follows.
< ultraviolet irradiation conditions >
Electrodeless lamp H bulb using Fusion, Co., Ltd
Illuminance of 500mW/cm2 and light quantity of 200mJ/cm2
EYE GRAPHICS CO, manufactured by LTD, "UVPF-36", was used as UV illuminance and light quantity meter "
[ test example 2] (measurement of adhesive force)
A light release type release sheet was peeled from the laminates prepared in preparation examples 1 to 5, and the exposed adhesive layer was bonded to an easy-adhesion layer of a polyethylene terephthalate (PET) film (TOYOBO co., ltd., product name "PET a 4300", thickness: 100 μm) having an easy-adhesion layer, to obtain a release sheet/adhesive layer/PET film laminate. The laminate thus obtained was cut into a width of 25mm and a length of 100mm, and used as a sample.
After a heavy-release type release Sheet was peeled from the sample in an atmosphere of 23 ℃ and 50% RH and the exposed adhesive layer was attached to soda-lime Glass (manufactured by Nippon Sheet Glass co., ltd.), the sample was pressurized at 0.5MPa and 50 ℃ for 20 minutes by using an autoclave manufactured by Kurihara manual inc. Thereafter, after the sheet was left to stand at 23 ℃ and 50% RH for 24 hours, the adhesion (N/25mm) was measured at a peel speed of 300mm/min and a peel angle of 180 degrees using a tensile tester (ORIENTEC Co., LTD., product, Tensilon). Conditions other than those described herein were determined in accordance with JIS Z0237: 2009 to perform the measurement. The results are shown in Table 2.
In addition, the laminates of preparation examples 4 and 5 were applied to soda lime glass and pressurized using an autoclave in the same manner as described above, and then the adhesive layer was irradiated with ultraviolet rays through the soda lime glass, and then the adhesive force after leaving to stand for 24 hours was also measured in the same manner as described above. The irradiation conditions of ultraviolet rays were the same as in test example 1.
[ test example 3] (measurement of storage modulus (G'))
The adhesive layers of the laminates prepared in preparation examples 1 to 5 were laminated in a plurality of layers to obtain a laminate having a thickness of 3 mm. A cylindrical body (height 3mm) having a diameter of 8mm was punched out from the laminate of the obtained adhesive layer, and this was used as a sample.
The above sample was measured for storage modulus (G') (MPa) under the following conditions according to the torsional shear method using a viscoelasticity measuring apparatus (available from REMOMETRIC corporation, DYNAMIC ANALAYZER) in accordance with JIS K7244-6. The results are shown in Table 3.
Measuring frequency: 1Hz
Measuring temperature: 23 deg.C
In addition, with respect to the adhesive agent layers of the laminates of preparation examples 4 and 5, the storage modulus (G') before and after irradiation of the laminate of the adhesive agent layers with ultraviolet rays was measured. The irradiation conditions of ultraviolet rays were the same as in test example 1.
[ test example 4] (measurement of 100% modulus)
The adhesive agent layers of the laminates prepared in preparation examples 1 to 5 were laminated in a plurality of layers, and the total thickness was set to 800 μm, and then samples of 10mm in width by 75mm in length were cut out. The sample was set in a tensile testing machine (ORIENTEC co., ltd., product name "Tensilon") at a tensile speed of 200 mm/min under an environment of 23 ℃ and 50% RH so that a sample measurement portion was 10mm wide by 25mm long (in the tensile direction), and the stress value at which the tensile rate became 100% was calculated (measured) as a 100% modulus (kPa) at a stress-bending line (SS curve). The results are shown in Table 3.
In addition, with respect to the adhesive layers of the laminates of preparation examples 4 and 5, the 100% modulus (kPa) before and after irradiation of ultraviolet rays to the laminate of the adhesive layers was measured. The irradiation conditions of ultraviolet rays were the same as in test example 1.
In addition, the adhesive agent layers of the adhesive sheets obtained in examples 1 to 6 and comparative examples 6 to 7 were also measured for 100% modulus (kPa) by the same method as described above (for comparative examples 1 to 5, the test was omitted because the results were the same as those of preparation examples 1 to 5). However, in examples and comparative examples other than example 2, the adhesive agent layer (3-layer structure) was laminated in a plurality of layers, and the total thickness was 750 μm. The results are shown in Table 4. In addition, the 100% modulus (kPa) before and after irradiation of ultraviolet rays to the adhesive layer of the adhesive sheets obtained in examples 1 to 6 and comparative example 6 was measured. The irradiation conditions of ultraviolet rays were the same as in test example 1.
[ test example 5 ] (evaluation of blister resistance)
The adhesive layer of the laminate prepared in preparation examples 1 to 5 and the adhesive layer of the adhesive sheet obtained in examples 1 to 6 and comparative examples 1 to 7 were sandwiched between a transparent conductive film of a polyethylene terephthalate film (OIKE & co., ltd., ITO film, thickness: 125 μm) provided with a transparent conductive film of tin-doped indium oxide (ITO) on one side and a Polycarbonate (PC) plate (MITSUBISHI GAS CHEMICAL COMPANY, inc., iupilon sheet MR58, thickness: 1mm) or an acrylic plate (MITSUBISHI GAS CHEMICAL COMPANY, inc., iupilon sheet MR200, thickness: 1mm) of polymethyl methacrylate (PMMA), to obtain a laminate.
The laminate thus obtained was autoclaved at 50 ℃ under 0.5MPa for 30 minutes. Then, the adhesive agent layer was cured by irradiating ultraviolet rays through a PC board or an acrylic board to the adhesive agent layer under the same ultraviolet irradiation conditions as in test example 1 (except for the adhesive agent layers of preparation examples 1 to 3, comparative examples 1 to 3, and comparative example 7).
The sample obtained as described above was left at 23 ℃ for 15 hours under normal pressure. Then, the resultant was stored at 85 ℃ and 85% RH for 72 hours. Then, whether or not the adhesive agent layer had bubbles, floating or peeling was confirmed by visual observation, and the blister resistance was evaluated in accordance with the following criteria. The results are shown in tables 3 and 4.
Pah … was completely free of bubbles, floating and peeling.
O … only generated bubbles having a diameter of 0.1mm or less.
X … produced bubbles, buoying or peeling greater than 0.1mm in diameter.
[ test example 6 ] (measurement of step following Rate)
Ultraviolet curable ink (Teiku Printing Inks Mfg. Co., Ltd., product name "POS-911 ink" manufactured by Ltd.) was screen-printed on the surface of a glass plate (manufactured by NSG Precision Co., Ltd., product name "Corning glass Eagle XG", 90mm in length × 50mm in width × 0.5mm in thickness) in a frame shape (outer shape: 90mm in length × 50mm in width, 5mm in width) so as to be coated to any one of 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, and 60 μm in thickness. Then, ultraviolet rays are irradiated(80W/cm2Two metal halide lamps having a lamp height of 15cm and a belt speed of 10 to 15 m/min), and curing the printed ultraviolet curable ink to produce a printed ultraviolet curable ink having a step (height of step: any one of 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, and 60 μm).
One release sheet was peeled from each of the laminates prepared in preparation examples 1 to 5 and the adhesive sheets obtained in examples and comparative examples, and the exposed adhesive layer was bonded to an easy-to-adhere layer of a polyethylene terephthalate film (TOYOBO co., ltd., product name "PET a 4300" thickness: 100 μm) having an easy-to-adhere layer. Then, the other release sheet is peeled off to expose the adhesive layer. The laminate was laminated on each step glass plate using a laminator (product name "LPD 3214" manufactured by fujiapla inc.) so that the adhesive layer covered the entire frame-shaped printing surface. Then, the autoclave treatment was carried out at 50 ℃ and 0.5MPa for 30 minutes.
The adhesive layer was cured by irradiating ultraviolet rays through a PET film under the same ultraviolet irradiation conditions as in test example 1 (except for the adhesive layers of preparation examples 1 to 3, comparative examples 1 to 3, and comparative example 7).
The evaluation samples obtained as described above were stored under high temperature and high humidity conditions of 85 ℃ and 85% RH for 72 hours (durability test), and then the step following property was evaluated. The level difference following property is determined based on whether or not the printing level difference is completely filled by the adhesive agent layer, and if bubbles, floating, peeling, or the like are observed on the surface of the printing level difference and the adhesive agent layer, it is determined that the printing level difference cannot be followed. Here, the level difference following property was evaluated as a level difference following rate (%) represented by the following formula. The results are shown in tables 3 and 4.
The step following ratio (%) { (height of step (μm) which remains in a filled state without bubbles, floating, peeling, or the like after the durability test))/(thickness of adhesive layer) } × 100
[ test example 7 ] (evaluation of processability)
The adhesive sheets obtained in examples and comparative examples were cut by an automatic cutter (an Ogino Seisakusho Co., Ltd., product name "super cutter OSS-PN1 type N-L"). The cut surface (length: 100mm) of the adhesive sheet after cutting was confirmed by visual observation, and workability was evaluated according to the following criteria. The results are shown in Table 4.
O: no bleeding phenomenon in the adhesive layer
X: the overflow phenomenon exists in the adhesive layer
[ Table 1]
Figure BDA0001132516800000421
[ Table 2]
Figure BDA0001132516800000431
[ Table 3]
Figure BDA0001132516800000432
[ Table 4]
Figure BDA0001132516800000441
As is clear from table 4, the pressure-sensitive adhesive sheets obtained in the examples were excellent in both the step following property and the blister resistance, and the processability was good.
Industrial applicability
The pressure-sensitive adhesive sheet of the present invention can be suitably used, for example, for bonding a protective panel having a step difference to a desired display body constituting member.

Claims (5)

1. A method for manufacturing a display body including one display body constituting member, another display body constituting member, and an adhesive layer which is located between the one display body constituting member and the other display body constituting member and bonds the one display body constituting member and the other display body constituting member to each other,
the adhesive layer is provided with:
a first adhesive layer which is an outer layer on one surface side;
a second adhesive layer which is an outer layer on the other surface side; and
a third adhesive layer as an intermediate layer between the first adhesive layer and the second adhesive layer,
the adhesive constituting the first adhesive layer and the adhesive constituting the second adhesive layer are acrylic adhesives,
the storage modulus (G ') at 23 ℃ of the adhesive constituting the first adhesive layer and the storage modulus (G') of the adhesive constituting the second adhesive layer are respectively more than 0.1MPa,
the third adhesive layer is composed of an active energy ray-curable adhesive,
a storage modulus (G ') at 23 ℃ before curing of the active energy ray-curable adhesive is lower than the storage modulus (G ') at 23 ℃ of the adhesive constituting the first adhesive layer and the storage modulus (G ') at 23 ℃ of the adhesive constituting the second adhesive layer and is 0.06MPa or more,
the thickness of the third adhesive layer is 25 [ mu ] m or more and 150 [ mu ] m or less,
a ratio of a thickness of the third adhesive agent layer to a total thickness of the first adhesive agent layer and the second adhesive agent layer is 0.3 or more and 3 or less,
after the one display body constituent member and the other display body constituent member are bonded to each other by the adhesive layer, the adhesive layer is cured by irradiating active energy rays through the active energy ray-transmitting member of the one display body constituent member and the other display body constituent member.
2. A method for manufacturing a display body including one display body constituting member, another display body constituting member, and an adhesive layer which is located between the one display body constituting member and the other display body constituting member and bonds the one display body constituting member and the other display body constituting member to each other,
the adhesive layer is provided with:
a first adhesive layer which is an outer layer on one surface side;
a second adhesive layer which is an outer layer on the other surface side; and
a third adhesive layer as an intermediate layer between the first adhesive layer and the second adhesive layer,
the adhesive constituting the first adhesive layer and the adhesive constituting the second adhesive layer are acrylic adhesives,
the 100% modulus of each of the adhesive constituting the first adhesive layer and the adhesive constituting the second adhesive layer is 60kPa or higher,
the third adhesive layer is composed of an active energy ray-curable adhesive,
the 100% modulus before curing of the active energy ray-curable adhesive is lower than the 100% modulus of the adhesive constituting the first adhesive layer and the 100% modulus of the adhesive constituting the second adhesive layer,
the storage modulus (G') at 23 ℃ before curing of the active energy ray-curable adhesive is 0.06MPa or more,
the thickness of the third adhesive layer is 25 [ mu ] m or more and 150 [ mu ] m or less,
a ratio of a thickness of the third adhesive agent layer to a total thickness of the first adhesive agent layer and the second adhesive agent layer is 0.3 or more and 3 or less,
after the one display body constituent member and the other display body constituent member are bonded to each other by the adhesive layer, the adhesive layer is cured by irradiating active energy rays through the active energy ray-transmitting member of the one display body constituent member and the other display body constituent member.
3. The method of manufacturing a display body according to claim 1 or 2,
the adhesive constituting the first adhesive layer and the adhesive constituting the second adhesive layer are active energy ray non-curable adhesives.
4. The method of manufacturing a display according to claim 1 or 2, wherein the total thickness of the adhesive layer is 50 μm or more and 300 μm or less.
5. The method of manufacturing a display body according to claim 1 or 2, wherein the one display body constituting member has a step at least on a side surface to be bonded.
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