CN111440543B - Adhesive composition, adhesive sheet, and display - Google Patents

Adhesive composition, adhesive sheet, and display Download PDF

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Publication number
CN111440543B
CN111440543B CN201911395951.2A CN201911395951A CN111440543B CN 111440543 B CN111440543 B CN 111440543B CN 201911395951 A CN201911395951 A CN 201911395951A CN 111440543 B CN111440543 B CN 111440543B
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adhesive
meth
acrylate
mass
adhesive layer
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CN111440543A (en
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藤井结加
荒井隆行
高桥洋一
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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
    • 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
    • C09J133/10—Homopolymers or copolymers of methacrylic 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
    • 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
    • C08K5/5415—Silicon-containing compounds containing oxygen containing at least one Si—O bond
    • 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
    • C09J133/062—Copolymers with monomers not covered by C09J133/06
    • C09J133/066—Copolymers with monomers not covered by C09J133/06 containing -OH groups
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
    • C09J7/38—Pressure-sensitive adhesives [PSA]
    • C09J7/381—Pressure-sensitive adhesives [PSA] based on macromolecular compounds obtained by reactions involving only carbon-to-carbon unsaturated bonds
    • C09J7/385—Acrylic polymers
    • 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
    • C09J7/40—Adhesives in the form of films or foils characterised by release liners
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
    • G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
    • G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
    • G06F3/041—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
    • 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

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Theoretical Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Human Computer Interaction (AREA)
  • General Physics & Mathematics (AREA)
  • Physics & Mathematics (AREA)
  • Adhesives Or Adhesive Processes (AREA)
  • Adhesive Tapes (AREA)
  • Liquid Crystal (AREA)
  • Laminated Bodies (AREA)

Abstract

The invention provides an adhesive composition, an adhesive sheet and a display, which can inhibit the resistance value change of an electrode to be small. The adhesive composition contains a (meth) acrylate polymer (A) and a silane coupling agent (B) having alkoxysilyl groups at both ends. The silane coupling agent (B) is preferably a compound represented by the following general formula (I) [ chemical formula 1 ]]
Figure DDA0002346299570000011
R in the formula 1 Is a divalent hydrocarbon group which may have a nitrogen atom; r in the formula 2 ～R 7 Each independently is an alkyl group.

Description

Adhesive composition, adhesive sheet, and display
Technical Field
The present invention relates to an adhesive composition, an adhesive and an adhesive sheet which can be used for a display such as a touch panel, and a display using the same.
Background
In recent years, touch panels have been widely used as displays for various mobile electronic devices such as smartphones and tablet terminals. As a touch panel, there are a resistive film type, a capacitive type, and the like, and in the mobile electronic device as described above, a capacitive type is mainly used.
As an electrode for a touch panel, a transparent conductive film made of a metal oxide such as tin-doped indium oxide (ITO) is generally used, and recently, a metal electrode made of a mesh-like metal wiring, for example, a silver electrode has been proposed. However, when a conventional adhesive is used in contact with the electrode as described above, the electrode is corroded by time change or high-temperature and high-humidity conditions, and the resistance value changes, which causes a driving failure of the touch panel.
In contrast, patent document 1 discloses an adhesive film for a polarizing plate, which is formed from an adhesive composition for a polarizing plate containing a non-carboxylic acid (meth) acrylic copolymer, an isocyanate curing agent, and an epoxy curing agent. In patent document 1, it is intended to reduce the acid value by using a non-carboxylic acid (meth) acrylic copolymer, thereby exhibiting a corrosion inhibition effect and reducing the rate of change in resistance value.
Prior art literature
Patent literature
Patent document 1: japanese patent application laid-open No. 2017-031406
Disclosure of Invention
Technical problem to be solved by the invention
However, as in patent document 1, when only a non-carboxylic acid-based (meth) acrylic copolymer is used, it is difficult to suppress the change in resistance value to be small under severe durable conditions.
The present invention has been made in view of the above-described actual situation, and an object thereof is to provide an adhesive composition, an adhesive sheet, and a display that can suppress a change in the resistance value of an electrode to be small.
Technical means for solving the technical problems
In order to achieve the above object, the present invention provides an adhesive composition comprising a (meth) acrylate polymer (a) and a silane coupling agent (B) having alkoxysilyl groups at both ends (invention 1).
When the adhesive obtained from the adhesive composition of the invention (invention 1) is used by contacting it with an electrode made of a metal or a metal oxide, the change in resistance value of the electrode made of a metal (particularly silver wiring) or a metal oxide (particularly an ITO film) can be suppressed even after the durability condition (for example, after the durability condition is left for 1000 hours in a hot and humid environment of 85 ℃ and 85% rh or a high temperature environment of 95 ℃).
In the above invention (invention 1), the silane coupling agent (B) is preferably a compound (invention 2) represented by the following general formula (I).
[ chemical formula 1]
Figure BDA0002346299550000021
R in the formula 1 Is a divalent hydrocarbon group which may have a nitrogen atom; r in the formula 2 ～R 7 Each independently is an alkyl group.
In the above invention (invention 2), R in the general formula (I) is preferably 1 Comprising an alkylene group having 1 to 10 carbon atoms (invention 3).
In the above invention (invention 2, 3), R in the general formula (I) is preferably 1 Is a divalent hydrocarbon group having no sulfur atom in the main chain (invention 4).
In the above inventions (inventions 1 to 4), the adhesive composition preferably contains a crosslinking agent (C) (invention 5).
In the above inventions (inventions 1 to 5), the (meth) acrylate polymer (a) preferably does not contain a carboxyl group-containing monomer as a monomer unit constituting the polymer (invention 6).
In the above inventions (inventions 1 to 6), the (meth) acrylate polymer (a) preferably contains a hydroxyl group-containing monomer in an amount of 6 mass% or more and 35 mass% or less as a monomer unit constituting the polymer (invention 7).
In the above inventions (inventions 1 to 7), the adhesive composition is preferably used for forming an adhesive in contact with an electrode composed of a metal or a metal oxide (invention 8).
In a second aspect, the present invention provides an adhesive (invention 9) obtained by crosslinking the adhesive composition (inventions 1 to 8).
In a third aspect, the present invention provides an adhesive sheet comprising two release sheets and an adhesive layer sandwiched between the release sheets so as to be in contact with the release surfaces of the two release sheets, wherein the adhesive layer is composed of the adhesive (invention 9) (invention 10).
Fourth, the present invention provides a display body including: the display device is characterized in that the first display device component member and/or the second display device component member has an electrode made of metal or metal oxide on at least a surface on which the first display device component member and/or the second display device component member are bonded, and the adhesive layer is an adhesive layer (invention 11) of the adhesive sheet (invention 10).
Effects of the invention
According to the adhesive composition, the adhesive sheet and the display of the present invention, the change in the resistance value of the electrode can be suppressed to be small.
Drawings
Fig. 1 is a cross-sectional view of an adhesive sheet according to an embodiment of the present invention.
Fig. 2 is a cross-sectional view showing one configuration example of the touch panel.
Fig. 3 is a plan view of the silver wiring electrode plate used in test example 2.
Description of the reference numerals
1: an adhesive sheet; 11: an adhesive layer; 12a, 12b: a release sheet; 2: a touch panel; 3: a display module; 4: an adhesive layer; 5a: a first membrane sensor; 5b: a second membrane sensor; 51: a base material film; 52: an electrode; 6: a cover material; 7: printing a layer; 8: a PET film; 9a: a first silver wiring; 9b: a second silver wiring; 91a, 91b: comb teeth; 92a, 92b: a gap portion; 93a, 93b: a connecting part; 94a, 94b: protrusion (pad).
Detailed Description
Hereinafter, embodiments of the present invention will be described.
[ adhesive composition ]
The adhesive composition of the present embodiment (hereinafter, sometimes referred to as "adhesive composition P") contains a (meth) acrylate polymer (a) and a silane coupling agent (B) having alkoxysilyl groups at both ends, and preferably further contains a crosslinking agent (C). In the present specification, (meth) acrylate means both acrylate and methacrylate. Other similar terms are also the same. In addition, "polymer" also includes the concept of "copolymer".
The adhesive composition P of the present embodiment is preferably used for forming an adhesive that contacts an electrode made of a metal or a metal oxide. By containing the (meth) acrylate polymer (a) and the silane coupling agent (B) having alkoxysilyl groups at both ends together in the adhesive composition P, it is possible to suppress a change in the resistance value of an electrode made of a metal (particularly silver wiring) or a metal oxide (particularly an ITO film) even after a durable condition (for example, after being left for 1000 hours in a hot and humid environment of 85 ℃ and 85% rh or a high-temperature environment of 95 ℃). Therefore, if the electrode is an electrode of the touch panel, the reliability of the touch panel is improved. This effect is thought to be mainly due to the effect of the alkoxysilyl groups present at both ends of the silane coupling agent (B) to prevent moisture from entering the adjacent electrode.
In addition, the hydrophilicity of the resulting adhesive is increased by the effect of the alkoxysilyl groups present at both ends of the silane coupling agent (B). It is presumed that even when the adhesive having such high hydrophilicity is left under high temperature and high humidity conditions, when the adhesive returns to normal temperature and normal humidity, moisture immersed in the adhesive under the high temperature and high humidity conditions is easily removed from the adhesive, and as a result, whitening of the adhesive is suppressed. Therefore, the adhesive obtained by crosslinking the adhesive composition P of the present embodiment is also excellent in wet heat whitening resistance.
Further, the silane coupling agent (B) does not adversely affect the (meth) acrylate polymer (A) or its crosslinked product. The adhesive obtained from the adhesive composition P containing the silane coupling agent (B) exhibits good adhesion to an adherend, particularly to a glass member. Thus, the obtained adhesive has excellent durability, and, for example, even when left for 1000 hours in a hot and humid environment of 85 ℃ and 85% RH or a high temperature environment of 95 ℃, it is possible to suppress occurrence of defects such as lifting and peeling at the interface with an adherend.
The adhesive obtained from the adhesive composition P of the present embodiment may be an active energy ray-curable adhesive cured by irradiation with active energy rays, or may be an inactive energy ray-curable adhesive cured without irradiation with active energy rays. In the case of the active energy ray-curable adhesive, the adhesive composition P preferably further contains an active energy ray-curable component (D).
(1) Each component is composed of
(1-1) (meth) acrylate Polymer (A)
The (meth) acrylate polymer (a) preferably contains a reactive functional group-containing monomer having a reactive functional group in the molecule as a monomer constituting the polymer. By containing the reactive functional group-containing monomer, the reactive functional group-containing monomer reacts with a crosslinking agent (C) described later via a reactive functional group derived from the reactive functional group-containing monomer, thereby forming a crosslinked structure (a three-dimensional network structure), and an adhesive having a predetermined cohesive force is obtained.
The reactive functional group-containing monomer contained in the (meth) acrylate polymer (a) as the monomer unit constituting the polymer is preferably a monomer having a hydroxyl group in the molecule (hydroxyl group-containing monomer), a monomer having a carboxyl group in the molecule (carboxyl group-containing monomer), a monomer having an amino group in the molecule (amino group-containing monomer), or the like. These reactive functional group-containing monomers may be used singly or in combination of two or more.
Among the reactive functional group-containing monomers, hydroxyl group-containing monomers having excellent reactivity with the crosslinking agent (C) and resistance to wet heat whitening and having little adverse effect on the electrode are particularly preferred.
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 and 4-hydroxybutyl (meth) acrylate are preferable, and 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate are more preferable from the viewpoint of reactivity with a crosslinking agent. These hydroxyl group-containing monomers may be used alone or in combination of two or more.
The (meth) acrylate polymer (a) preferably contains 6 mass% or more, particularly preferably 9 mass% or more, and further preferably 12 mass% or more of a reactive functional group-containing monomer (particularly a hydroxyl group-containing monomer) as a monomer unit constituting the polymer. The (meth) acrylate polymer (a) preferably contains 35 mass% or less, particularly preferably 30 mass% or less, and further preferably 25 mass% or less of a reactive functional group-containing monomer (particularly a hydroxyl group-containing monomer) as a monomer unit constituting the polymer.
When the (meth) acrylate polymer (a) contains a reactive functional group-containing monomer as a monomer unit in the above-described amount, the silane coupling agent (B) tends to segregate easily on the surface layer of the obtained adhesive layer, and the effect of suppressing the change in resistance value becomes more excellent. In addition, when the (meth) acrylate polymer (a) contains a reactive functional group-containing monomer as a monomer unit in the above-described amount, the balance between the adhesive force and the cohesive force of the obtained adhesive can be satisfactorily achieved. Further, when the (meth) acrylate polymer (a) contains 6 mass% or more of a hydroxyl group-containing monomer as a monomer unit, hydroxyl groups as hydrophilic groups remain in a predetermined amount in the obtained adhesive. As a result, the adhesive obtained is more excellent in wet heat whitening resistance by the synergistic effect with the silane coupling agent (B) having alkoxysilyl groups at both ends.
The (meth) acrylate polymer (a) preferably does not contain a carboxyl group-containing monomer as a monomer unit constituting the polymer. Since the carboxyl group is an acid component, there is a possibility that the resistance value of the electrode contacted with the adhesive may be changed in general. However, the above-mentioned "no carboxyl group-containing monomer" means that the carboxyl group-containing monomer is allowed to be contained to such an extent that the electrode contacted by the resulting adhesive is not adversely affected. Specifically, the (meth) acrylate polymer (a) may contain a carboxyl group-containing monomer as a monomer unit in an amount of 0.1 mass% or less, preferably 0.01 mass% or less, and more preferably 0.001 mass% or less.
Further, the (meth) acrylic acid ester polymer (a) preferably contains an alkyl (meth) acrylate as a monomer unit constituting the polymer. This can exhibit good adhesion.
In addition to the reactive functional group-containing monomer, the (meth) acrylate polymer (a) particularly preferably contains, as monomer units constituting the polymer, an alkyl (meth) acrylate having a glass transition temperature (Tg) of 0 ℃ or less and an alkyl group having 2 to 20 carbon atoms, and a monomer having a glass transition temperature (Tg) of more than 0 ℃ as a homopolymer.
The (meth) acrylate polymer (a) can exhibit excellent adhesion by containing, as a monomer unit constituting the polymer, an alkyl (meth) acrylate having a glass transition temperature (Tg) of 0 ℃ or less and an alkyl group having 2 to 20 carbon atoms (hereinafter, sometimes referred to as "low Tg alkyl acrylate"). From this point of view, the (meth) acrylic acid ester polymer (a) preferably contains 30 mass% or more, particularly preferably 40 mass% or more, and further preferably 50 mass% or more of a low Tg alkyl acrylate as a monomer unit constituting the polymer. In addition, the (meth) acrylic acid ester polymer (a) preferably contains 90 mass% or less, particularly preferably 80 mass% or less, and further preferably 70 mass% or less of the above-mentioned low Tg alkyl acrylate as a monomer unit constituting the polymer, as the upper limit value. If the upper limit of the content of the low Tg alkyl acrylate is the above, an appropriate amount of other monomer component can be introduced into the (meth) acrylate polymer (a).
As the low Tg alkyl acrylate, for example, ethyl acrylate (Tg-20deg.C), n-butyl acrylate (Tg-55deg.C), isobutyl acrylate (Tg-26deg.C), n-octyl acrylate (Tg-65deg.C), isooctyl acrylate (Tg-58 deg.C), 2-ethylhexyl acrylate (Tg-70 deg.C), 2-ethylhexyl methacrylate (Tg-10 deg.C), isononyl acrylate (Tg-58 deg.C), isodecyl acrylate (Tg-60 deg.C), isodecyl methacrylate (Tg-41 deg.C), lauryl acrylate (Tg-23 deg.C), lauryl methacrylate (Tg-65 deg.C), tridecyl acrylate (Tg-55deg.C), tridecyl methacrylate (-40 deg.C), and isostearyl acrylate (Tg-18 deg.C) are preferable. Among them, from the viewpoint of more effectively imparting tackiness, the low Tg alkyl acrylate is more preferably a homopolymer having a Tg of-40℃or less, particularly preferably-50℃or less. Specifically, n-butyl acrylate and 2-ethylhexyl acrylate are particularly preferable. These low Tg alkyl acrylates may be used alone or in combination of two or more. The alkyl group in the alkyl (meth) acrylate having 2 to 20 carbon atoms in the alkyl group means a linear, branched or cyclic alkyl group.
In addition, from the viewpoint of suppressing the change in the resistance value of the electrode under durable conditions by increasing the hydrophobicity of the obtained adhesive layer, at least a part of the low Tg alkyl acrylate is preferably composed of an alkyl (meth) acrylate in which the alkyl group has 5 or more carbon atoms, and more preferably composed of an alkyl (meth) acrylate in which the alkyl group has 7 or more carbon atoms. Specifically, 2-ethylhexyl acrylate is particularly preferable. Further, from the viewpoint of suppressing the change in the resistance value of the electrode, the proportion of the alkyl (meth) acrylate having 5 or more carbon atoms (preferably 7 or more) in the alkyl (meth) acrylate as a whole is preferably 40% by mass or more, more preferably 60% by mass or more, particularly preferably 80% by mass or more, and most preferably 100% by mass.
In addition, by containing a monomer having a glass transition temperature (Tg) exceeding 0 ℃ as a homopolymer (hereinafter sometimes referred to as "hard monomer") as a monomer unit constituting the polymer, the resulting adhesive is easily provided with appropriate cohesive force and adhesiveness. Thus, the resulting adhesive layer is likely to suppress the occurrence of defects such as lifting or peeling at the interface with the adherend even after being left under durable conditions (for example, durable conditions of 1000 hours in a hot and humid environment of 85 ℃ and 85% rh or a high temperature environment of 95 ℃).
Examples of the hard monomer include acrylic monomers such as methyl acrylate (Tg 10 ℃), methyl methacrylate (Tg 105 ℃), ethyl methacrylate (Tg 65 ℃), n-butyl methacrylate (Tg 20 ℃), isobutyl methacrylate (Tg 48 ℃), t-butyl methacrylate (Tg 107 ℃), n-octadecyl acrylate (Tg 30 ℃), n-octadecyl methacrylate (Tg 38 ℃), cyclohexyl acrylate (Tg 15 ℃), cyclohexyl methacrylate (Tg 66 ℃)), phenoxyethyl acrylate (Tg 5 ℃), phenoxyethyl methacrylate (Tg 54 ℃), benzyl methacrylate (Tg 54 ℃), isobornyl acrylate (Tg 94 ℃), isobornyl methacrylate (Tg 180 ℃), acryloylmorpholine (Tg 145 ℃), adamantyl acrylate (Tg 115 ℃), adamantyl methacrylate (Tg 141 ℃), dimethylacrylamide (Tg 89 ℃), acrylamide (Tg 165 ℃), and the like), vinyl acetate (Tg 32 ℃), styrene (Tg 80 ℃) and the like, and preferable examples thereof are from the viewpoint of compatibility. These hard monomers may be used alone or in combination of two or more.
In particular, the glass transition temperature (Tg) of the hard monomer is more preferably 60 ℃ or higher, particularly preferably 90 ℃ or higher, from the viewpoint of providing the obtained adhesive with appropriate cohesive force and tackiness and effectively suppressing occurrence of defects such as lifting or peeling at the interface with the adherend. In addition, in view of compatibility with or copolymerization with other monomers constituting the (meth) acrylate polymer (a), the glass transition temperature (Tg) of the hard monomer is preferably 250 ℃ or less, more preferably 200 ℃ or less, and particularly preferably 150 ℃ or less.
The hard monomer preferably contains at least one selected from the group consisting of methyl methacrylate, isobornyl acrylate, and acryloylmorpholine, from the viewpoint of preventing adverse effects on other characteristics such as compatibility with the silane coupling agent (B) and further exhibiting the performance of the hard monomer. Particular preference is given to using methyl methacrylate alone or simultaneously with isobornyl acrylate and acryloylmorpholine.
The (meth) acrylate polymer (a) preferably contains 5 mass% or more, more preferably 10 mass% or more, and particularly preferably 15 mass% or more of the hard monomer as a monomer constituting the polymer, from the viewpoint of imparting an appropriate cohesive force and tackiness to the obtained adhesive.
In addition, from the viewpoint of making the obtained (meth) acrylate polymer (a) excellent in compatibility with the silane coupling agent (B), it is preferable to contain 50 mass% or less, more preferably 40 mass% or less, and particularly preferably 30 mass% or less of the above hard monomer as a monomer constituting the polymer.
The (meth) acrylic acid ester polymer (a) may contain other monomers as monomer units constituting the polymer, if necessary. As the other monomer, a monomer having a reactive functional group is preferably not contained so as not to interfere with the action of the reactive functional group-containing monomer. Examples of the other monomer include alkoxyalkyl (meth) acrylates such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate. These other monomers may be used alone or in combination of two or more.
The (meth) acrylate polymer (a) is preferably a solution polymer obtained by a solution polymerization method. By using a solution polymer, a polymer having a high molecular weight can be easily obtained, and an adhesive having excellent durability (for example, an adhesive having no problems such as floating or peeling at the interface with an adherend, etc. even when left for 1000 hours in a hot and humid environment of 85 ℃ and 85% RH or a high temperature environment of 95 ℃) can be obtained.
The polymerization form of the (meth) acrylic acid ester polymer (a) may be a random copolymer or a block copolymer.
The lower limit of the weight average molecular weight of the (meth) acrylic acid ester polymer (a) is preferably 20 ten thousand or more, particularly preferably 30 ten thousand or more, and further preferably 40 ten thousand or more. When the lower limit value of the weight average molecular weight of the (meth) acrylic acid ester polymer (a) is the above, the obtained adhesive has excellent durability (for example, no occurrence of defects such as floating or peeling at the interface with an adherend even when left under a hot and humid environment of 85 ℃ and 85% rh or a high temperature environment of 95 ℃ for 1000 hours). The weight average molecular weight in the present specification is a value in terms of standard polystyrene measured by Gel Permeation Chromatography (GPC).
The upper limit of the weight average molecular weight of the (meth) acrylic acid ester polymer (a) is preferably 120 ten thousand or less, particularly preferably 90 ten thousand or less, and further preferably 75 ten thousand or less. When the upper limit of the weight average molecular weight of the (meth) acrylate polymer (a) is the above, the obtained adhesive exhibits suitable tackiness.
In the adhesive composition P, the (meth) acrylate polymer (a) may be used alone or in combination of two or more.
(1-2) silane coupling agent (B)
As described above, by including the silane coupling agent (B) having alkoxysilyl groups at both ends in the adhesive composition P of the present embodiment, it is possible to suppress a change in the resistance value of the electrode with which the obtained adhesive is in contact. The adhesive thus obtained has improved adhesion to an adherend, particularly to a glass member, and is excellent in durability (for example, no occurrence of defects such as lifting or peeling at the interface with the adherend even when left under a hot and humid environment of 85 ℃ and 85% RH or a high temperature environment of 95 ℃ for 1000 hours).
The silane coupling agent (B) is an organosilicon compound having alkoxysilyl groups at both ends, and is preferably a compound represented by the following general formula (I).
[ chemical formula 2]
Figure BDA0002346299550000101
R in the formula 1 Is a divalent hydrocarbon group which may have a nitrogen atom; r in the formula 2 ～R 7 Each independently is an alkyl group.
R is as described above 1 The number of carbon atoms of the divalent hydrocarbon group is preferably 1 to 10, particularly preferably 3 to 9, further preferably 4 to 8, and most preferably 5 to 7 from the viewpoint of the effect of suppressing the resistance value of the metal electrode (particularly silver electrode). The hydrocarbon group is preferably a saturated hydrocarbon group, and particularly preferably a chain saturated hydrocarbon group. Further, the above-mentioned hydrocarbon group preferably contains an alkylene group, and particularly preferably an alkylene group. The number of carbon atoms of the alkylene group is preferably 1 to 10, particularly preferably 3 to 9, further preferably 4 to 8, and most preferably 5 to 7 from the viewpoint of the effect of suppressing the resistance value of the metal electrode (particularly silver electrode).
When R is as above 1 When having a nitrogen atom, the nitrogen atom may be present in a side chain of the above-mentioned hydrocarbon group, but is preferably present in a main chain of the above-mentioned hydrocarbon group. When R is as above 1 R is a nitrogen atom 1 The number of nitrogen atoms contained in (a) is preferably 1 to 5, particularly preferably 2 to 3. The nitrogen atom is preferably an amino group or an amide group, particularly preferably an amino group, and further preferably is present as a secondary amine or a tertiary amine in the main chain of the hydrocarbon group.
When R is as above 1 R is a nitrogen atom 1 Preferably containing- (CH) m -NH-backbone, more preferably containing- (CH) m -NH-(CH) n -a skeleton, particularly preferably containing- (CH) m -NH-(CH) n -NH-backbone, further preferably comprising- (CH) m -NH-(CH) n -NH-(CH) p -a skeleton. The numbers m, n and p are positive integers, preferably 1 to 5, and particularly preferably 2 to 4.
Preferably R is as defined above 1 Has no sulfur atom in the main chain. If the main chain has a sulfur atom, a metal sulfide is easily formed starting from the interface between the adhesive and an electrode made of a metal (particularly silver) or a metal oxide (particularly ITO) in a durability test environment (for example, a hot and humid environment of 85 ℃ and 85% rh or a high temperature environment of 95 ℃). This may hinder the effect of suppressing the resistance change.
R is as described above 2 ～R 7 The number of carbon atoms of the alkyl group is preferably 1 to 6, particularly preferably 1 to 4, further preferably 1 to 2, and most preferably 1. In addition, R is preferably as described above 2 ～R 7 Are all the same alkyl groups, most preferably are all methyl groups.
The lower limit value of the content of the silane coupling agent (B) in the adhesive composition P is preferably 0.01 part by mass or more, more preferably 0.1 part by mass or more, particularly preferably 0.16 part by mass or more, and further preferably 0.22 part by mass or more, relative to 100 parts by mass of the (meth) acrylate polymer (a). The upper limit of the content is preferably 1.5 parts by mass or less, particularly preferably 1 part by mass or less, and further preferably 0.6 part by mass or less. When the content of the silane coupling agent (B) is in the above range, the effect of the silane coupling agent (B) can be effectively exhibited, the change in resistance value of the electrode can be more effectively suppressed, and the resistance to wet-heat whitening and durability can be further improved.
(1-3) crosslinking agent (C)
The adhesive composition P preferably contains a crosslinking agent (C). By forming a three-dimensional network structure by crosslinking the adhesive composition P with the crosslinking agent (C) and the (meth) acrylate polymer (a), the cohesive force of the obtained adhesive can be improved and durability can be improved.
The crosslinking agent (C) may be a crosslinking agent that reacts with a reactive group of the (meth) acrylate polymer (a), and examples thereof include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, amine-based crosslinking agents, melamine-based crosslinking agents, aziridine-based crosslinking agents, hydrazine-based crosslinking agents, aldehyde-based crosslinking agents, oxazoline-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, and ammonium salt-based 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 excellent in reactivity with the hydroxyl group thereof is preferably used. In addition, the crosslinking agent (C) may be used singly 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 toluene 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 of these compounds, and adducts of these compounds with low-molecular active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane and castor oil. Among them, from the viewpoint of reactivity with hydroxyl groups, trimethylol propane-modified aromatic polyisocyanates are preferred, and trimethylol propane-modified toluene diisocyanate is particularly preferred.
The lower limit value of the content of the crosslinking agent (C) in the adhesive composition P is preferably 0.001 part by mass or more, particularly preferably 0.01 part by mass or more, and further preferably 0.1 part by mass or more, relative to 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 further preferably 1 part by mass or less. By setting the content of the crosslinking agent (C) within the above range, the cohesive force of the obtained adhesive becomes a preferable cohesive force, and an adhesive having more excellent durability can be obtained. Further, the upper limit of the content of the crosslinking agent (C) is preferably 0.5 parts by mass or less from the viewpoint of more effectively suppressing the change in the resistance value of the electrode.
(1-4) active energy ray-curable component (D)
When the adhesive obtained from the adhesive composition P of the present embodiment is used as an active energy ray-curable adhesive, the adhesive composition P preferably contains an active energy ray-curable component (D). The adhesive obtained by crosslinking (thermal crosslinking) the adhesive composition P by containing the active energy ray-curable component (D) becomes an active energy ray-curable adhesive. In the active energy ray-curable adhesive, it is presumed that the active energy ray-curable components (D) are polymerized with each other by curing by irradiation of active energy rays after the adhesion of the adherend, and the polymerized active energy ray-curable components (D) are entangled with the crosslinked structure (three-dimensional network structure) of the (meth) acrylate polymer (a). The adhesive having such a high-dimensional structure has high cohesive force and exhibits high film strength, and thus has more excellent durability.
The active energy ray-curable component (D) is not particularly limited as long as it is a component cured by irradiation with active energy rays and can obtain the above-mentioned effects, and may be any of a monomer, an oligomer, or a polymer, or may be a mixture of these. Among them, a polyfunctional acrylate monomer that can give an adhesive having more excellent durability is preferable.
Examples of the polyfunctional acrylate monomer include difunctional types such as 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, neopentyl glycol hydroxypivalate di (meth) acrylate, dicyclopentyl di (meth) acrylate, caprolactone-modified dicyclopentenyl di (meth) acrylate, ethylene oxide-modified phosphoric acid di (meth) acrylate, di (acryloyloxyethyl) isocyanurate, allylated cyclohexyl di (meth) acrylate, ethoxylated bisphenol a diacrylate, 9-bis [4- (2-acryloyloxyethoxy) phenyl ] fluorene; trifunctional 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, epsilon-caprolactone-modified tris (2- (meth) acryloyloxyethyl) isocyanurate, and the like; tetra-functionality such as diglycerol tetra (meth) acrylate and pentaerythritol tetra (meth) acrylate; five (methyl) acrylic ester of propionic acid modified dipentaerythritol, etc.; and hexafunctionality such as dipentaerythritol hexa (meth) acrylate and caprolactone-modified dipentaerythritol hexa (meth) acrylate. Among the above, from the viewpoint of imparting an appropriate cohesive force and tackiness to the obtained adhesive and effectively suppressing occurrence of defects such as lifting or peeling at the interface with an adherend, polyfunctional acrylate monomers containing an isocyanurate structure in the molecule such as di (acryloyloxyethyl) isocyanurate, tri (acryloyloxyethyl) isocyanurate, epsilon-caprolactone-modified tri (2- (meth) acryloyloxyethyl) isocyanurate and the like are preferable, polyfunctional acrylate monomers having a trifunctional or higher degree and containing an isocyanurate structure in the molecule are more preferable, and epsilon-caprolactone-modified tri (2- (meth) acryloyloxyethyl) isocyanurate is particularly preferable. These polyfunctional acrylate monomers may be used singly or in combination of two or more. In addition, from the viewpoint of compatibility with the (meth) acrylate polymer (a), the molecular weight of the polyfunctional acrylate monomer is preferably less than 1000.
As the active energy ray-curable component (D), an active energy ray-curable acrylate oligomer may be used. Examples of such acrylate oligomers include polyester acrylates, epoxy acrylates, urethane acrylates, polyether acrylates, polybutadiene acrylates, silicone acrylates, and the like.
The weight average molecular weight of the acrylic oligomer is preferably 50,000 or less, particularly preferably 1,000 to 50,000, and further preferably 3,000 to 40,000. These acrylate oligomers may be used singly or in combination of two or more.
As the active energy ray-curable component (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: a copolymer of a (meth) acrylate and a monomer having a crosslinkable functional group in the molecule is used, and a compound having a (meth) acryloyl group and a group reactive with the crosslinkable functional group is reacted with a part of the crosslinkable functional group of the copolymer.
The weight average molecular weight of the above-mentioned acrylate-based polymer is preferably about 5 to 90 tens of thousands, and particularly preferably about 10 to 50 tens of thousands.
The active energy ray-curable component (D) may be used by selecting one from the polyfunctional acrylate monomer, the acrylate oligomer and the addition acrylate polymer, or two or more of them may be used in combination, or may be used in combination with other active energy ray-curable components.
When the adhesive composition P contains the active energy ray-curable component (D), the content of the active energy ray-curable component (D) is preferably 2 parts by mass or more, more preferably 3 parts by mass or more, particularly preferably 4 parts by mass or more, relative to 100 parts by mass of the (meth) acrylate polymer (a). The content is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, particularly preferably 8 parts by mass or less, and further preferably 6 parts by mass or less. By setting the content of the active energy ray-curable component (D) within the above range, the durability of the adhesive after active energy ray curing can be further improved.
(1-5) photopolymerization initiator (E)
When the adhesive obtained from the adhesive composition P of the present embodiment is used as an active energy ray-curable adhesive, when ultraviolet rays are used as active energy rays, the adhesive composition P preferably further contains a photopolymerization initiator (E). By containing the photopolymerization initiator (E) in this manner, the active energy ray-curable component (D) can be efficiently polymerized, and the polymerization curing time and the irradiation amount of active energy rays can be reduced.
Examples of the photopolymerization initiator (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-phenylpropane-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl ] -2-morpholino-propane-1-one, 4- (2-hydroxyethoxy) phenyl-2- (hydroxy-2-propyl) ketone, benzophenone, p-phenylbenzophenone, 4' -diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-t-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2, 4-dimethylthioxanthone, 2, 4-diethylthioxanthone, dimethylbenzone, 2-dimethylbenzoyl-1-hydroxy-2- (4-methylbenzophenone, 2-dimethylbenzoyl) ketone, 2-dimethylbenzoyl-2-hydroxy-2-methylbenzoyl-1-ketone, and the like. These photopolymerization initiators may be used alone or in combination of two or more.
When the adhesive composition P contains the active energy ray-curable component (D) and the photopolymerization initiator (E), the lower limit of the content of the photopolymerization initiator (E) is preferably 0.1 part by mass or more, particularly preferably 1 part by mass or more, and further preferably 5 parts by mass or more, relative to 100 parts by mass of the active energy ray-curable component (D). The upper limit is preferably 30 parts by mass or less, particularly preferably 20 parts by mass or less, and further preferably 15 parts by mass or less.
(1-6) various additives
Various additives commonly used for acrylic adhesives, such as rust inhibitors, antistatic agents, tackifiers, antioxidants, light stabilizers, softeners, fillers, refractive index regulators, and the like, may be added to the adhesive composition P as needed.
The adhesive composition P is a mixture of various components remaining in the adhesive layer directly or in a reacted state, and the components removed in the drying step or the like, for example, a polymerization solvent or a dilution solvent described later, are not included in the adhesive composition P.
The adhesive composition P of the present embodiment contains the silane coupling agent (B) having alkoxysilyl groups at both ends, whereby the obtained adhesive exhibits an excellent resistance change suppression effect, but further contains the rust inhibitor, whereby the resistance change suppression effect (particularly, resistance change suppression effect in a hot and humid environment of 85 ℃ and 85% rh) can be further improved.
Examples of the rust inhibitor include an azole compound having a hydroxyl group, a triazole compound, a benzotriazole compound, a thiazole compound, a benzothiazole compound, an imidazole compound, a benzimidazole compound, a phosphorus compound, an amine compound, a nitrite compound, and a surfactant, and among these, benzotriazole-based rust inhibitors are preferable from the viewpoint of corrosion resistance. In addition, the rust inhibitor may be used singly or in combination of two or more.
Examples of the benzotriazole-based rust inhibitor include 1H-benzotriazole, tolylbenzotriazole, 1- [ N, N-bis (2-ethylhexyl) aminomethyl ] benzotriazole, and 1- [ N, N-bis (2-ethylhexyl) aminomethyl ] methylbenzotriazole.
The content of the rust inhibitor in the adhesive composition P is preferably 0.001 parts by mass or more, more preferably 0.005 parts by mass or more, particularly preferably 0.01 parts by mass or more, and further preferably 0.1 parts by mass or more, relative to 100 parts by mass of the (meth) acrylate polymer (a). The content is preferably 1.0 part by mass or less, particularly preferably 0.7 part by mass or less, and further preferably 0.5 part by mass or less. By setting the rust inhibitor in the above range, the effect of promoting the resistance change suppression effect (particularly the resistance change suppression effect in a hot and humid environment at 85 ℃ and 85% rh) can be exhibited well, and the adhesion is not hindered.
(2) Preparation of adhesive composition
The adhesive composition P can be prepared by: the (meth) acrylate polymer (a) is prepared, and the obtained (meth) acrylate polymer (a) is mixed with the silane coupling agent (B) while adding the crosslinking agent (C), the active energy ray-curable component (D), the photopolymerization initiator (E), the additive, and the like as required.
The (meth) acrylate polymer (a) can be prepared by polymerizing a mixture of monomer units constituting the polymer using a usual radical polymerization method. The polymerization of the (meth) acrylate polymer (a) may be carried out by a solution polymerization method or the like using a polymerization initiator as needed. Examples of the polymerization solvent include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, and methyl ethyl ketone, and two or more of them may be used simultaneously.
Examples of the polymerization initiator include azo compounds and organic peroxides, and two or more of them may be used simultaneously. As the azo-based compound, there is used, examples thereof include 2,2 '-azobisisobutyronitrile, 2' -azobis (2-methylbutyronitrile), 1 '-azobis (cyclohexane-1-carbonitrile), 2' -azobis (2, 4-dimethylvaleronitrile), 2 '-azo-bis- (2, 4-dimethyl-4-methoxypentanenitrile), and dimethyl azodiisobutyrate, 4' -azobis (4-cyanovaleric acid), 2 '-azobis (2-hydroxymethylpropionitrile), 2' -azobis [2- (2-imidazolin-2-yl) propane ], and the like.
Examples of the organic peroxide include benzoyl peroxide, t-butyl peroxybenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di (2-ethoxyethyl) peroxydicarbonate, t-butyl peroxyneodecanoate, t-butyl peroxypivalate, 3, 5-trimethylhexanoyl peroxide, dipropyl peroxide, diacetyl peroxide, and the like.
In the polymerization step, a chain transfer agent such as 2-mercaptoethanol is blended to adjust the weight average molecular weight of the polymer obtained.
After the (meth) acrylate polymer (a) is obtained, a silane coupling agent (B), and, according to the desired crosslinking agent (C), active energy ray-curable component (D), photopolymerization initiator (E), additives, diluent solvents, and the like are added to the solution of the (meth) acrylate polymer (a), and thoroughly mixed, thereby obtaining a solvent-diluted adhesive composition P (coating solution).
As the diluent solvent, for example, aliphatic hydrocarbons such as hexane, heptane, cyclohexane, etc. can be used; 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; cellosolve solvents such as ethyl cellosolve and the like.
The concentration and viscosity of the coating solution prepared in this way are not particularly limited as long as they are within a coatable range, and may be appropriately selected according to the circumstances. For example, the adhesive composition P is diluted so that the concentration thereof is 10 to 40 mass%. In addition, in the case of obtaining the coating solution, it is not necessary to add a diluting solvent or the like, but if the adhesive composition P has a viscosity or the like that enables coating, the diluting solvent may not be added. 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 diluting solvent.
[ Adhesives ]
The adhesive of the present embodiment is formed by crosslinking the adhesive composition P. Crosslinking of the adhesive composition P can be performed by heat treatment. In addition, the drying treatment when the diluting solvent or the like of the adhesive composition P to be applied is volatilized may also be used as the heating treatment.
In the heat treatment, the heating temperature is preferably 50 to 150℃and particularly preferably 70 to 120 ℃. The heating time is preferably 30 seconds to 10 minutes, and particularly preferably 50 seconds to 2 minutes. After the heat treatment, a curing period of about 1 to 2 weeks may be set at normal temperature (e.g., 23 ℃ C., 50% RH) as needed. When the aging period is required, an adhesive layer is formed after the aging period is passed, and when the aging period is not required, an adhesive layer is formed after the heat treatment is completed.
The lower limit of the gel fraction of the adhesive according to the present embodiment is preferably 30% or more, particularly preferably 40% or more, and further preferably 45% or more. If the lower limit of the gel fraction of the adhesive is the above, the cohesive force is improved and the durability is improved. The upper limit of the gel fraction is preferably 85% or less, more preferably 80% or less, particularly preferably 75% or less, and further preferably 73% or less. If the upper limit of the gel fraction of the adhesive is the above, the adhesive does not become too hard and the adhesive force becomes higher. The method for measuring the gel fraction of the adhesive is as shown in the test examples described later.
[ adhesive sheet ]
As shown in fig. 1, the adhesive sheet 1 of the present embodiment is composed of two release sheets 12a, 12b and an adhesive layer 11, and the adhesive layer 11 is sandwiched between the two release sheets 12a, 12b so as to be in contact with the release surfaces of the two release sheets 12a, 12 b. However, in the adhesive sheet 1, the release sheets 12a, 12b are not essential components, and are peeled and removed when the adhesive sheet 1 is used. 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 having releasability even if the release treatment is not performed.
(1) Adhesive layer
The adhesive layer 11 is composed of the above adhesive. The lower limit value of the thickness (value measured in accordance with JIS K7130) of the adhesive layer 11 is preferably 10 μm or more, particularly preferably 25 μm or more, and further preferably 45 μm or more. By setting the lower limit value of the thickness of the adhesive layer 11 to the above, excellent adhesive force can be sufficiently exhibited. The upper limit value of the thickness of the adhesive layer 11 is preferably 300 μm or less, more preferably 250 μm or less, particularly preferably 100 μm or less, and further preferably 70 μm or less. By setting the upper limit value of the thickness of the adhesive layer 11 to the above, the workability becomes good. The adhesive layer 11 may be formed as a single layer or may be formed by stacking a plurality of layers.
(2) Stripping sheet
The release sheets 12a and 12b are not particularly limited, and known plastic films can be used. For example, polyethylene film, polypropylene film, polybutylene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polyethylene naphthalate film, polybutylene terephthalate film, polyurethane film, ethylene-vinyl acetate film, ionomer resin film, ethylene- (meth) acrylic acid copolymer film, ethylene- (meth) acrylic acid ester copolymer film, polystyrene film, polycarbonate film, polyimide film, fluororesin film, and the like can be used. In addition, crosslinked films of these films may also be used. Further, these films may be laminated films.
The release surfaces (particularly, the surfaces in contact with the adhesive layer 11) of the release sheets 12a and 12b are preferably subjected to a release treatment. Examples of the release agent used for the release treatment include release agents such as alkyd, silicone, fluorine, unsaturated polyester, polyolefin, and wax. In the release sheets 12a and 12b, 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 12a, 12b is not particularly limited, but is usually about 20 to 150 μm.
(3) Production of adhesive sheet
As one example of the production of the adhesive sheet 1, the coating liquid of the adhesive composition P is applied to the release surface of one release sheet 12a (or 12 b), and the adhesive composition P is heat-treated to crosslink the adhesive composition P to form a coating layer, and then the coating layer is laminated on the release surface of the other release sheet 12b (or 12 a). When the curing period is required, the adhesive layer 11 is formed by the coating layer, and when the curing period is not required, the adhesive layer 11 is directly formed by the coating layer. Thus, the adhesive sheet 1 was obtained. The conditions for heat treatment and curing are as described above.
As another example of the production of the adhesive sheet 1, the coating liquid of the adhesive composition P is applied to the release surface of one release sheet 12a, and the adhesive composition P is crosslinked to form a coating layer by heat treatment, thereby obtaining the release sheet 12a with a coating layer. The coating solution of the adhesive composition P is applied to the release surface of the other release sheet 12b, and the adhesive composition P is crosslinked to form a coating layer by heat treatment, thereby obtaining the release sheet 12b with a coating layer. Then, the coated release sheet 12a and the coated release sheet 12b are bonded so that the two coated layers are in contact with each other. When the curing period is required, the laminated coating layer is formed into the adhesive layer 11 by providing the curing period, and when the curing period is not required, the laminated coating layer is directly formed into the adhesive layer 11. Thus, the adhesive sheet 1 was obtained. According to this production example, even in the case where the adhesive layer 11 is thick, the production can be stably performed.
As a method of applying the coating solution of the adhesive composition P, for example, a bar coating method, a blade coating method, a roll coating method, a blade coating method, a die coating method, a gravure coating method, or the like can be used.
(4) Physical properties of adhesive sheet (adhesive force)
The lower limit of the adhesion of the adhesive sheet 1 of the present embodiment to soda lime glass is preferably 10N/25mm or more, particularly preferably 13N/25mm or more, and further preferably 15N/25mm or more. When the lower limit value of the adhesion force is the above, the durability of the adhesive layer 11 becomes more excellent. The upper limit of the adhesion force is preferably 45N/25mm or less, more preferably 40N/25mm or less, particularly preferably 30N/25mm or less, and further preferably 24N/25mm or less. If the upper limit of the adhesive force is the above, good re-workability can be obtained, and re-adhesion can be achieved even when an adhesion error occurs.
The above-mentioned adhesive force is basically an adhesive force measured by 180-degree peeling method according to JIS Z0237:2009, and is a value obtained by making a measurement sample 25mm wide and 100mm long, attaching the measurement sample to an adherend, pressurizing at 0.5MPa and 50℃for 20 minutes, then standing at normal pressure and 23℃for 24 hours under 50% RH, and then measuring at a peeling rate of 300 mm/min.
[ display body ]
The display of the present embodiment includes a first display element constituting member, a second display element constituting member, and an adhesive layer for bonding the first display element constituting member and the second display element constituting member to each other. The adhesive layer is composed of the adhesive of the present embodiment described above. Here, the first display element-constituting member and/or the second display element-constituting member has an electrode made of a metal or a metal oxide on at least the surface on the side to be bonded (the adhesive layer side). Preferably, the second display element constituting member has the electrode at least on the surface on the bonded side.
Examples of the display body include a Liquid Crystal (LCD) display, a Light Emitting Diode (LED) display, an organic electroluminescence (organic EL) display, and electronic paper, and may be a touch panel. The display body may be a member constituting a part of the display body.
The first display body constituent member is preferably a protective panel composed of a laminate including a glass plate, a plastic plate, or the like, in addition to the glass plate, the plastic plate, or the like. The first display element-constituting member may have a step on the adhesive layer-side surface. In this case, specifically, it is preferable to have a level difference by the print layer. The printed layer is generally formed in a frame shape.
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, and barium borosilicate glass. The thickness of the glass plate is not particularly limited, but is usually 0.1 to 5mm, preferably 0.2 to 2mm.
The plastic sheet is not particularly limited, and examples thereof include an acryl sheet and a polycarbonate sheet. The thickness of the plastic plate is not particularly limited, but is usually 0.2 to 5mm, preferably 0.4 to 3mm.
In addition, various functional layers (an electrode layer, a silica layer, a hard coat layer, an antiglare layer, and the like) may be provided on one surface or both surfaces of the glass plate or the plastic plate, or an optical member may be laminated.
The material constituting the printing layer is not particularly limited, and a known material for printing can be used. The lower limit value of the thickness of the print layer, that is, the height of the step 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. By setting the lower limit value to be equal to or more than the above, it is possible to sufficiently ensure the hiding of the electric wiring or the like from the observer side. 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. By setting the upper limit value to the above-described range, deterioration in level difference follow-up property of the adhesive layer with respect to the printed layer can be prevented.
The second display constituent member is preferably an optical member to be attached to the first display constituent member, a display 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 that is a part of the display module, or a laminate including the display module, which has an electrode composed of a metal or a metal oxide on at least a surface on the adhesive layer side.
Examples of the optical member include a film sensor, an electrode film, a metal nanowire film, and a wire grid polarizing film.
Examples of the electrode made of a metal include metal wiring (including mesh-like, grid-like, nanowire-like wiring) made of silver, silver alloy, copper alloy, or the like. Metal wirings constituting electrodes of the touch panel can be particularly preferably exemplified, and specifically, metal wirings contained in the film sensor can be preferably exemplified. Among the above metal wirings, a metal wiring composed of nanoparticles of silver or silver alloy is preferable, and for this metal wiring, excellent resistance change suppression effect by the adhesive layer 11 is easily exhibited.
Examples of the electrode made of a metal oxide include an electrode obtained by patterning a transparent conductive film made of a metal oxide such as tin-doped indium oxide (ITO) or zinc oxide. Among the above, an electrode obtained by patterning a transparent conductive film made of ITO is particularly preferable, and the ITO transparent conductive film is likely to exhibit an excellent effect of suppressing the change in resistance due to the adhesive layer 11.
As an example of the display body of the present embodiment, fig. 2 shows a capacitive touch panel 2. The touch panel 2 includes a display module 3, a first film sensor 5a laminated on the display module 3 via an adhesive layer 4, a second film sensor 5b laminated on the first film sensor 5a via a first adhesive layer 11, and a cover material 6 laminated on the second film sensor 5b via a second adhesive layer 11. Since the printed layer 7 is formed on the surface of the cover material 6 on the second adhesive layer 11 side, there is a step due to the presence or absence of the printed layer 7. In the present embodiment, the cover material 6 corresponds to the first display element constituting member, the second film sensor 5b corresponds to the second display element constituting member, or the second film sensor 5b corresponds to the first display element constituting member, and the first film sensor 5a corresponds to the second display element constituting member.
In view of the effect of suppressing the change in the resistance value, it is preferable that the first adhesive layer 11 and the second adhesive layer 11 in the touch panel 2 are both the adhesive layer 11 of the adhesive sheet 1. When the first adhesive layer 11 or the second adhesive layer 11 is not the adhesive layer 11 of the adhesive sheet 1, the adhesive constituting the adhesive layer may be an acrylic adhesive, a rubber adhesive, a silicone adhesive, a urethane adhesive, a polyester adhesive, a polyvinyl ether adhesive, or the like, and among these, an acrylic adhesive is preferable.
The adhesive layer 4 may be formed by the adhesive layer 11 of the adhesive sheet 1, or may be formed by another adhesive or adhesive sheet. In the latter case, the adhesive constituting the adhesive layer 4 may be an acrylic adhesive, a rubber adhesive, a silicone adhesive, a urethane adhesive, a polyester adhesive, a polyvinyl ether adhesive, or the like, and among them, an acrylic adhesive is preferable.
The first film sensor 5a and the second film sensor 5b of the present embodiment each include a base film 51 and an electrode 52 formed on the base film 51. The substrate film 51 is not particularly limited, and for example, a polyethylene terephthalate film, an acryl film, a polycarbonate film, or the like can be used.
As the electrode 52, the electrode described above can be exemplified. In general, one of the electrodes 52 of the first film sensor 5a and the electrodes 52 of the second film sensor 5b constitutes a circuit pattern in the X-axis direction, and the other constitutes a circuit pattern in the Y-axis direction.
In fig. 2, the electrode 52 of the second film sensor 5b of the present embodiment is located on the upper side of the second film sensor 5 b. On the other hand, in fig. 2, the electrode 52 of the first film sensor 5a is located on the upper side of the first film sensor 5a, but the present invention is not limited thereto, and the electrode 52 may be located on the lower side of the first film sensor 5 a.
An example of the method for manufacturing the touch panel 2 will be described below.
As the adhesive sheet 1, a first adhesive sheet 1 and a second adhesive sheet 1 are prepared. One release sheet 12a is peeled off from the first adhesive sheet 1, and the exposed adhesive layer 11 (first adhesive layer) is bonded to the first film sensor 5a so as to be in contact with the electrode 52 of the first film sensor 5a. Further, one release sheet 12a is peeled off from the second adhesive sheet 1, and the exposed adhesive layer 11 (second adhesive layer 11) is bonded to the second film sensor 5b so as to be in contact with the electrode 52 of the second film sensor 5b.
Then, the other release sheet 12b of the first adhesive sheet 1 is peeled off, and the exposed first adhesive layer 11 is bonded to the surface of the second film sensor 5b opposite to the side on which the second adhesive layer 11 is laminated (the exposed surface of the base film 51 of the second film sensor 5 b) so that the two are in contact with each other. Thus, a laminate is obtained in which the release sheet 12b, the second adhesive layer 11, the second film sensor 5b, the first adhesive layer 11, and the first film sensor 5a are laminated in this order.
Next, the adhesive layer 4 provided on the release sheet is bonded to the surface of the laminate on the first film sensor 5a side (the exposed surface of the base film 51 of the first film sensor 5 a). Then, the release sheet 12b is peeled off from the laminate, and the cover material 6 is bonded to the exposed second adhesive layer 11 so that the printed layer 7 side of the cover material 6 is in contact with the second adhesive layer 11. The above lamination gives a structure in which the cover material 6, the second adhesive layer 11, the second film sensor 5b, the first adhesive layer 11, the first film sensor 5a, the adhesive layer 4, and the release sheet are laminated in this order.
Then, the release sheet is peeled off from the structure, and the structure is bonded to the display module 3 so that the exposed adhesive layer 4 contacts the display module 3. Thereby, the touch panel 2 shown in fig. 2 is manufactured.
Here, when the first adhesive layer 11 and/or the second adhesive layer 11 are/is constituted by an active energy ray-curable adhesive, active energy rays are irradiated to the adhesive layer 11 in the above-described structure or touch panel 2. Thus, the active energy ray-curable component (D) in the adhesive layer 11 is polymerized, and the adhesive layer 11 is cured to form a cured adhesive layer. The irradiation of the adhesive layer 11 with energy rays is usually performed from one side of the structure or the touch panel 2, preferably from the side of the cover material 6.
The active energy ray is an active energy ray having an energy quantum in an electromagnetic wave or a charged particle beam, and specifically, ultraviolet rays, electron beams, and the like are mentioned. Among active energy rays, ultraviolet rays which are easy to handle are particularly preferable.
The irradiation of ultraviolet rays can be performed by using a high-pressure mercury lamp, a fusion H lamp, a xenon lamp, etc., and the irradiation amount of ultraviolet rays is preferably 50 to 1000mW/cm in an illuminometer 2 About, preferably 100 to 600mW/cm 2 Left and right. Further, the light quantity is preferably 50 to 10000mJ/cm 2 More preferably 80 to 5000mJ/cm 2 Particularly preferably 200 to 2000mJ/cm 2 . On the other hand, the electron beam irradiation may be performed using an electron beam accelerator or the like, and the irradiation amount of the electron beam is preferably about 10 to 1000 krad.
The lower limit of the gel fraction of the adhesive (adhesive after irradiation with active energy rays) constituting the adhesive layer after curing is preferably 35% or more, particularly preferably 50% or more, and further preferably 65% or more. When the lower limit value of the gel fraction of the adhesive after irradiation with active energy rays is the above, the durability becomes higher. The upper limit of the gel fraction is preferably 85% or less, particularly preferably 80% or less, and further preferably 75% or less. If the upper limit value of the gel fraction of the adhesive after irradiation with active energy rays is the above, the adhesive layer can be prevented from being reduced in adhesive force and deteriorated in durability after curing. The method for measuring the gel fraction of the adhesive after irradiation with active energy rays is as follows.
The lower limit of the adhesion of the adhesive sheet having the cured adhesive layer to soda lime glass is preferably 10N/25mm or more, particularly preferably 20N/25mm or more, and further preferably 30N/25mm or more. If the lower limit value of the adhesion force is the above, durability as the obtained product (touch panel 2) becomes high. The upper limit of the adhesion force is not particularly limited, but is usually 60N/25mm or less, particularly 50N/25mm or less, and more particularly 45N/25mm or less.
The above-mentioned adhesion is basically measured by 180-degree peeling method according to JIS Z0237:2009, and is a value obtained by making a measurement sample 25mm wide and 100mm long, adhering the measurement sample to an adherend, pressurizing at 0.5MPa and 50℃for 20 minutes, irradiating with active energy rays (ultraviolet rays) under the conditions shown in test examples described later, standing at normal pressure and 23℃and 50% RH for 24 hours, and measuring at a peeling rate of 300 mm/minute.
Even in the case where the touch panel 2 is left in a durable condition, for example, a durable condition of being left in a hot and humid environment of 85 ℃ and 85% rh or a high temperature environment of 95 ℃ for 1000 hours, since the adhesive layer 11 in contact with the electrode 52 contains the silane coupling agent (B) having alkoxysilyl groups at both ends, the change in resistance value of the electrode 52 can be effectively suppressed.
Here, the change in the resistance value of the electrode 52 will be specifically described. When a laminate obtained by bonding soda lime glass and an ITO vapor deposited film via the adhesive layer 11 of the adhesive sheet 1 of the present embodiment is subjected to a durability test (left standing for 1000 hours in a hot and humid environment of 85 ℃ and 85% rh or in a high temperature environment of 95 ℃), the resistance change rate of the ITO vapor deposited film calculated by the following formula is preferably less than 400%, particularly preferably less than 350%, and further preferably less than 300%. The lower limit is not particularly limited, but is particularly preferably 0% or more. Similarly, when a laminate obtained by bonding soda lime glass and a silver wiring electrode plate via the adhesive layer 11 of the adhesive sheet 1 of the present embodiment is subjected to a durability test (left standing for 1000 hours in a hot and humid environment of 85 ℃ and 85% rh or in a high temperature environment of 95 ℃), the resistance change rate of the silver wiring electrode plate calculated by the following formula is preferably less than 50%, particularly preferably less than 30%, and further preferably less than 10%. The lower limit is not particularly limited, but is particularly preferably 0% or more.
Resistance change rate (%) = { (R-R) 0 )/R 0 }×100
Wherein R is 0 The initial resistance value (Ω) before the endurance test, and R is the resistance value (Ω) after the endurance test.
Details of the method for measuring the rate of change of the resistance value are shown in test examples described later.
Further, since the adhesive layer 11 is excellent in wet heat whitening resistance, whitening of the adhesive layer 11 can be suppressed even when the touch panel 2 is returned to normal temperature and normal humidity after being placed under, for example, high temperature and high humidity conditions (e.g., 85 ℃ and 85% rh).
The wet heat whitening resistance of the adhesive layer 11 of the present embodiment can be quantitatively evaluated by using the haze value. Specifically, an alkali-free glass having a thickness of 1.1mm and an acrylic resin plate made of polymethyl methacrylate having a thickness of 1mm were bonded via the adhesive layer 11 of the adhesive sheet 1 of the present embodiment, to obtain a laminate. The laminate was stored under a wet heat condition of 85℃and 85% RH for 120 hours, and then stored under a normal temperature and normal humidity condition of 23℃and 50% RH for 24 hours, and the haze value (%) before the wet heat condition was subtracted from the haze value (%) (measured according to JIS K7136:2000; the same applies hereinafter) to calculate the haze value increase (percentage point). Preferably, the haze value increase is less than 5 percent, particularly preferably less than 3 percent, and even more preferably less than 1 percent. If the haze value increases as described above, the haze value increases little even after the adhesive layer is left under hot and humid conditions, and whitening of the adhesive layer can be suppressed.
Further, since the adhesive layer 11 has excellent durability, it is possible to prevent the occurrence of defects such as lifting or peeling at the interface between the adhesive layer 11 and the adherend even when the touch panel 2 is left for 1000 hours in a hot and humid environment of 85 ℃ and 85% rh or a high temperature environment of 95 ℃.
The embodiments described above are described for easy understanding of the present invention, and are not described for limiting the present invention. Accordingly, each element disclosed in the above embodiments also covers all design changes and equivalents that fall within the technical scope of the present invention.
For example, any one of the release sheets 12a, 12b in the adhesive sheet 1 may be omitted. In the touch panel 2, the print layer 7 may not be formed on the cover material 6.
Examples
The present invention will be described in more detail with reference to examples, but the scope of the present invention is not limited to these examples.
Example 1
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 by a solution polymerization method. The molecular weight of the (meth) acrylate polymer (a) was measured by a method described later, and as a result, the weight average molecular weight (Mw) was 70 ten thousand.
2. Preparation of adhesive composition
100 parts by mass (solid content equivalent; same hereinafter) of the (meth) acrylic ester polymer (A) obtained in the above-mentioned step 1, 0.25 part by mass of the organosilicon compound represented by the following structural formula (II) as the silane coupling agent (B), and 0.23 part by mass of trimethylolpropane-modified toluene diisocyanate (TOYOCHEM CO., LTD. Manufactured by LTD. Product name "BHS 8515") as the crosslinking agent (C) were mixed and sufficiently stirred, and diluted with methyl ethyl ketone, thereby obtaining a coating solution of the adhesive composition.
[ chemical formula 3]
Figure BDA0002346299550000281
Here, the proportions (solid content conversion values) of the adhesive composition when the (meth) acrylate polymer (a) was set to 100 parts by mass (solid content conversion values) are shown in table 1. Further, the abbreviations, components, and the like described in table 1 are as follows.
[ (meth) acrylate Polymer (A) ]
2EHA: 2-ethylhexyl acrylate
MMA: methyl methacrylate
HEA: acrylic acid 2-hydroxy ethyl ester
IBXA: isobornyl acrylate
ACMO: n-acryloylmorpholine
[ silane coupling agent (B) ]
Structural formula (II): organosilicon compounds represented by the above structural formula (II)
Structural formula (III): an organosilicon compound represented by the following structural formula (III)
[ chemical formula 4]
Figure BDA0002346299550000282
Epoxy: 3-glycidoxypropyl trimethoxysilane (Shin-Etsu Chemical Co., ltd., product name "KBM-403")
Mercapto group: multifunctional silane coupling agent having mercapto group (Shin-Etsu Chemical Co., ltd., product name "X-12-1156")
[ Cross-linking agent (C) ]
Trimethylolpropane-modified toluene diisocyanate (TOYOCHEM CO., LTD. Manufactured by LTD. Product name "BHS 8515")
[ active energy ray-curable component (D) ]
Epsilon-caprolactone-modified tris (2-acryloyloxyethyl) isocyanurate (SHIN-NAKAMURA CHEMICAL CO., LTD. Manufactured, product name "NK Ester A-9300-1 CL")
[ photopolymerization initiator (E) ]
1:1 (mass ratio) mixture of 1-hydroxy-cyclohexyl-phenyl-ketone and benzophenone
[ antirust agent ]
1- [ N, N-bis (2-ethylhexyl) aminomethyl ] methylbenzotriazole
3. Production of adhesive sheet
The coating solution of the adhesive composition obtained in the above step 2 was applied to a release treated surface of a heavy release type release sheet (manufactured by Lintec Corporation under the product name "SP-PET 382150") in which one side of a polyethylene terephthalate film was release-treated with a silicone-based release agent, followed by heat treatment at 80 ℃ for 1 minute and heat treatment at 110 ℃ for 1 minute, thereby forming a coating layer (thickness: 50 μm).
Next, the coating layer on the heavy release sheet obtained above was bonded to a light release sheet (manufactured by Lintec Corporation, product name "SP-PET 381130") obtained by peeling one side of a polyethylene terephthalate film using a silicone-based release agent so that the release treated surface of the light release sheet was in contact with the coating layer, and cured under the conditions of 23 ℃ and 50% rh for 7 days, thereby producing an adhesive sheet composed of a structure of a heavy release sheet/adhesive layer (thickness: 50 μm)/light release sheet.
Examples 2 to 8 and comparative examples 1 to 4
An adhesive sheet was produced in the same manner as in example 1, except that the types and proportions of the monomers constituting the (meth) acrylic acid ester polymer (a), the weight average molecular weight of the (meth) acrylic acid ester polymer (a), the types and amounts of the silane coupling agent (B) and the amount of the crosslinking agent (C) were changed as shown in table 1. Further, rust inhibitors were further added to examples 3 and 7, and active energy ray-curable components (D) and photopolymerization initiators (E) were further added to examples 4, 5 and 8 and comparative example 4.
Here, the weight average molecular weight (Mw) is a polystyrene-equivalent weight average molecular weight measured using Gel Permeation Chromatography (GPC) and under the following conditions (GPC measurement).
< measurement conditions >
● GPC measurement device: TOSOH CORPORATION, HLC-8020
● GPC column (passing in the following order): TOSOH CORPORATION manufacture
TSK guard column HXL-H
TSK gel GMHXL(×2)
TSK gel G2000HXL
● Measuring solvent: tetrahydrofuran (THF)
● Measuring temperature: 40 DEG C
[ test example 1] (determination of gel fraction)
The adhesive sheets obtained in examples and comparative examples were cut into 80mm×80mm sizes, and the adhesive layer was wrapped in a polyester net (mesh size 200), and the mass thereof was measured with a precision balance, and the mass of the net alone was subtracted, whereby the mass of the adhesive itself was calculated. The mass at this time was designated as M1.
Then, the adhesive wrapped in the polyester net was immersed in ethyl acetate at room temperature (23 ℃) for 24 hours. The adhesive was then removed, 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 measured with a precision balance, and the mass of the adhesive itself was calculated by subtracting the individual mass of the net. The mass at this time was designated as M2. Gel fraction (%) was expressed as (M2/M1). Times.100. The results are shown in Table 2.
In the adhesive sheets of examples 4, 5, and 8 and comparative example 4, gel fraction before and after irradiation of Ultraviolet (UV) to the adhesive layer (irradiation from the side of the heavy release sheet) was measured. The irradiation conditions of ultraviolet rays were as follows.
< conditions for ultraviolet irradiation >
● Using high-pressure mercury lamps
● Illuminance of 200mW/cm 2 Light quantity 1000mJ/cm 2
● UV illuminance/light meter "UVPF-A1" manufactured by EYE GRAPHICS co., ltd.
[ test example 2] (evaluation of resistance value Change)
< production of silver Wiring electrode plate >
A silver paste (TOYOCHEM co., ltd., product name "RA FS 088") was applied to an adhesion-promoting treated surface of a polyethylene terephthalate (PET) film (manufactured by tolay INDUSTRIES, INC., product name "Lumirror U48", thickness: 125 μm) having an adhesion-promoting treatment on one surface thereof in a pattern shown in fig. 3 by a screen printing method. Then, the silver paste was cured by heat treatment at 135 ℃ for 30 minutes, thereby obtaining an electrode plate with silver wiring (silver wiring electrode plate).
As shown in fig. 3, the silver wiring is formed as a first silver wiring 9a having 6 comb teeth 91a and a second silver wiring 9b also having 6 comb teeth 91b on the PET film 8. Here, the interval between 6 comb teeth 91a in the first silver wire 9a is the gap 92a, and similarly, the interval between 6 comb teeth 91b in the second silver wire 9b is the gap 92b. The first silver wiring 9a and the second silver wiring 9b are formed in the following manner: the 5 comb teeth 91a of the first silver wire 9a are located in the gaps 92b of the second silver wire 9b, respectively, and the 5 comb teeth 91b of the second silver wire 9b are located in the gaps 92a of the first silver wire 9a, respectively. The 6 comb teeth 91a in the first silver wire 9a are connected by a connecting portion 93a, and the connecting portion 93a is provided with a protrusion 94a as a tab (terminal). Similarly, 6 comb teeth 91b in the second silver wire 9b are connected by a connecting portion 93b, and the connecting portion 93b is provided with a protrusion 94b as a tab.
The line widths of the 6 comb-teeth portions 91a in the first silver wire 9a and the line widths of the 6 comb-teeth portions 91b in the second silver wire 9b are 40 μm, respectively, and the distances between the adjacent comb- teeth portions 91a and 91b are 40 μm.
< production of measurement sample >
The adhesive layers of the adhesive sheets obtained in examples and comparative examples were laminated with soda lime glass (manufactured by ltd. In the longitudinal direction 70 mm. Times.150 mm. Times. 1.0mm;Nippon Sheet Glass Co. In the transverse direction) and an IT O vapor-deposited film (manufactured by OIKE & co., ltd. In the product name "tetolight TCF KH150NM H2-125-U6/T2", the ITO vapor-deposited film side was in contact with the adhesive layers). Then, a measurement sample A (ITO deposited film sample) was obtained by performing autoclave treatment at 50℃under 0.5M Pa for 20 minutes.
Further, soda lime glass (manufactured by ltd. In the longitudinal direction 70mm×150mm×thickness 1.0mm;Nippon Sheet Glass Co) was bonded to the silver wiring of the silver wiring electrode plate obtained in the above-described step via the adhesive layers of the adhesive sheets obtained in the examples and comparative examples. At this time, bonding is performed so that the protrusions 94a and 94b of the silver wirings 9a and 9b are exposed. Then, autoclave treatment was performed at 50℃and 0.5MPa for 20 minutes, whereby a measurement sample B (silver wiring electrode plate sample) was obtained.
The adhesive sheets of examples 4, 5, 8 and comparative example 4 were subjected to the autoclave treatment, and then the adhesive layer was irradiated with ultraviolet rays from the soda lime glass side under the same conditions as in test example 1, to obtain a measurement sample.
For the above measurement sample A, the initial resistance value R was measured using a non-contact resistivity tester (product name "EC-80" manufactured by NAPSON Co., ltd.) 0 (Ω). On the other hand, for the above measurement sample B, a voltage of 5V was applied between the protrusions 94a, 94B of the silver wirings 9a, 9B, and the initial resistance value R was measured 0 (Ω)。
Next, the measurement sample A, B was left to stand in a hot and humid environment at 85 ℃ and 85% rh or a high temperature environment at 95 ℃ for 1000 hours. Then, the sample was allowed to stand at 23℃and 50% RH for 24 hours under normal temperature and humidity conditions, and the resistance value (. OMEGA.) was measured in the same manner as the initial resistance value described above. This was used as the resistance value R after the endurance test. From the obtained measurement value, the resistance value change rate (%) was calculated by the following formula. The results are shown in Table 2.
Resistance change rate (%) = { (R-R) 0 )/R 0 }×100
Then, the resistance value change was evaluated according to the following criteria based on the above calculated resistance value change rate. The results are shown in Table 2.
And (3) the following materials: the change rate of the resistance value is less than 300 percent
O: the change rate of the resistance value is more than 300% and less than 350%
Delta: the change rate of the resistance value is more than 350% and less than 400%
X: the change rate of the resistance value is more than 400 percent
< evaluation criteria for silver Wiring electrode plate sample >
And (3) the following materials: the change rate of the resistance value is less than 10 percent
O: the rate of change of the resistance value is 10% or more and less than 30%
Delta: the rate of change of the resistance value is 30% or more and less than 50%
X: the change rate of the resistance value is more than 50 percent
[ test example 3] (measurement of adhesion)
The light release type release sheet was peeled from 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 (PET) film (TOYOBO co., ltd., product name "PET a4300", thickness: 100 μm) having an easy-to-adhere layer, to obtain a laminate of release sheet/adhesive layer/PET film. The obtained laminate was cut into a sheet having a width of 25mm and a length of 100mm, and the sheet was used as a sample.
The heavy release sheet was peeled off from the above sample at 23 ℃ under 50% rh, and the exposed adhesive layer was attached to soda lime glass (Nippon Sheet Glass co., manufactured by ltd.) and then pressed at 50 ℃ under 0.5MPa for 20 minutes using an autoclave manufactured by KURIHARA SEISAKUSHO co., ltd. Then, after being left at 23℃for 24 hours at 50% RH, the adhesive force (N/25 mm) was measured at a peeling speed of 300 mm/min and a peeling angle of 180 degrees using a tensile tester (ORIENTEC Co., LTD. Manufactured by LTD. Under the product name "TENSILON"). The conditions not described herein were measured based on JIS Z0237:2009. The results are shown in Table 2.
The adhesive sheets of examples 4, 5, and 8 and comparative example 4 were also measured for adhesive force after Ultraviolet (UV) irradiation. Specifically, after the autoclave treatment, the adhesive layer was irradiated with ultraviolet rays from the soda lime glass side under the same conditions as in test example 1. Then, after 24 hours of standing at 23℃and 50% RH, the adhesion (N/25 mm; after UV irradiation) was measured in the same manner as described above. The results are shown in Table 2.
Test example 4 (evaluation of resistance to whitening by damp-heat)
The adhesive layers of the adhesive sheets obtained in examples and comparative examples were sandwiched between alkali-free glass having a thickness of 1.1mm and an acrylic resin plate (manufactured by Mitsubishi ray co., ltd. Under the product name "acrylic MR-200") made of polymethyl methacrylate (PMMA) having a thickness of 1mm, to obtain a laminate.
The obtained laminate (sample) was subjected to autoclave treatment at 50℃and 0.5MPa for 20 minutes, and then left at normal pressure and 23℃and 50% RH for 24 hours. The laminate was measured for haze value (%) using a haze meter (NIPPON DENSHOKU INDUSTRIES Co., LTD, product name "NDH 2000") based on JIS K7136:2000. In the adhesive sheets of examples 4, 5, 8 and comparative example 4, after the autoclave treatment, the adhesive layer was irradiated with ultraviolet rays from the alkali-free glass side under the same conditions as those of test example 1.
The laminate was then stored under hot and humid conditions at 85℃and 85% RH for 120 hours. Then, the mixture was left at 23℃under normal temperature and humidity of 50% RH for 24 hours. The laminate was measured for haze value (%) using a haze meter (NIPPON DENSHOKU INDUSTRIES Co., LTD, product name "NDH 2000") based on JIS K7136:2000.
From the above results, the haze value before the wet heat condition was subtracted from the haze value after the wet heat condition, and the haze value increase (percentage point) after the wet heat condition was calculated. Based on the results, wet heat whitening resistance was evaluated according to the following criteria. The results are shown in Table 2.
And (3) the following materials: haze value rise of less than 1.0 percent
O: the haze value is increased to more than 1.0 percent and less than 3.0 percent
Delta: the haze value is increased to 3.0 percent or more and less than 5.0 percent
X: the haze value is increased to 5.0 percent or more
Test example 5 (evaluation of durability)
The measurement sample A, B obtained in the test example 2 (evaluation of resistance change) was left to stand in a hot and humid environment at 85℃and 85% RH or in a high-temperature environment at 95℃for 1000 hours. Then, the mixture was allowed to stand at 23℃under a normal temperature and humidity atmosphere of 50% RH for 24 hours. Then, the occurrence of bubbles or floating and peeling at the interface between the adhesive layer and the adherend was visually confirmed, and durability was evaluated according to the following criteria. The results are shown in Table 2.
And (3) the following materials: no bubbles, floating and peeling were generated at all.
O: a small amount of bubbles having a diameter of 0.1mm or less was generated.
Delta: more bubbles having a diameter of 0.1mm or less are generated.
X: bubbles exceeding 0.1mm in diameter are generated, and float or peel.
TABLE 1
Figure BDA0002346299550000351
/>
Figure BDA0002346299550000361
As is clear from table 2, the adhesive sheet obtained in the examples can suppress the change in resistance values of the ITO vapor deposited film and the silver wiring electrode plate. The adhesive sheet obtained in the examples also had excellent wet heat whitening resistance and durability.
Industrial applicability
The adhesive composition, adhesive and adhesive sheet of the present invention can be suitably used for a capacitive touch panel, for example. The display of the present invention is suitable as, for example, a capacitive touch panel.

Claims (7)

1. A display body is provided with: a first display element constituting member, a second display element constituting member, and an adhesive layer for bonding the first display element constituting member and the second display element constituting member to each other, wherein the display element is characterized in that,
at least one of the first display element constituting member and the second display element constituting member has an electrode made of a metal or a metal oxide on a surface on the bonded side,
The adhesive layer is composed of an adhesive agent which is crosslinked from an adhesive composition containing a (meth) acrylate polymer (A) and a silane coupling agent (B) having alkoxysilyl groups at both ends.
2. The display body according to claim 1, wherein the silane coupling agent (B) is a compound represented by the following general formula (I),
[ chemical formula 1]
Figure FDA0004051811730000011
R in the formula 1 Is a divalent hydrocarbon group which may have a nitrogen atom; r in the formula 2 ～R 7 Each independently is an alkyl group.
3. The display of claim 2, wherein R in formula (I) 1 Comprising an alkylene group having 1 to 10 carbon atoms.
4. The display of claim 2, wherein R in formula (I) 1 Is a 2-valent hydrocarbon group having no sulfur atom in the main chain.
5. The display according to claim 1, wherein the adhesive composition contains a crosslinking agent (C).
6. The display body according to claim 1, wherein the (meth) acrylate polymer (a) does not contain a carboxyl group-containing monomer as a monomer unit constituting the polymer.
7. The display according to claim 1, wherein the (meth) acrylate polymer (a) contains 6 mass% or more and 35 mass% or less of a hydroxyl group-containing monomer as a monomer unit constituting the polymer.
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JP2020114903A (en) 2020-07-30
TW202028265A (en) 2020-08-01

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