TWI895395B - Adhesive composition, adhesive, adhesive sheet and display - Google Patents

Abstract

The present invention is to provide an adhesive composition, adhesive, adhesive sheet, and display that effectively prevent and inhibit migration. The solution provided by the present invention is an adhesive composition comprising a (meth)acrylate polymer (A), a rust repellent (B), and a long-chain alkylamine (C); an adhesive formed by bridging the adhesive composition; and an adhesive sheet 1 comprising: two release sheets 12a and 12b; and an adhesive layer 11 that contacts the release surfaces of the two release sheets 12a and 12b to sandwich the release sheets 12a and 12b. The adhesive layer 11 is composed of the aforementioned adhesive.

Description

Adhesive composition, adhesive, adhesive sheet and display

The present invention relates to an adhesive composition, an adhesive, and an adhesive sheet that can be used for a display such as a touch panel, and a display using the same.

In recent years, touch panels have become increasingly common in displays for various mobile electronic devices, including smartphones and tablets. Touch panels come in various types, including resistive and capacitive, but capacitive is the predominant type used in mobile electronic devices, as described above.

With the recent push to increase the size of touchscreen panels, research is underway into using grid-like metal electrodes, such as copper or silver, as electrode materials for these touchscreens. However, when conventional adhesives come into contact with metal electrodes, particularly copper or silver, ion migration (electrochemical migration; sometimes simply referred to as "migration") can occur. Specifically, this can lead to electrode dissolution and wire breakage at the positive electrode, while dendritic crystals formed by precipitation of positive electrode components can cause short circuits at the negative electrode.

This migration is particularly prone to occur when voltage is applied to the electrodes under high temperature and high humidity conditions. When this migration occurs, the resistance value fluctuates, causing the touch panel to malfunction. In recent years, especially with the advancement of miniaturization and narrowing of electrode pitches, electrode disconnection and short circuits caused by migration have become more likely to occur, leading to a desire to fully prevent and control migration.

However, Patent Document 1 discloses an adhesive composition for touch panels containing a benzotriazole compound as a rustproofing agent. [Prior Art Document] [Patent Document]

[Patent Document 1] Japanese Patent Application Laid-Open No. 2014-177611

[Identify the problem to be solved]

However, even though benzotriazole compounds, used as rust preventers, have an anti-corrosion effect on metal wiring, they cannot fully prevent or suppress migration.

The present invention was made in light of the above-mentioned circumstances, and aims to provide an adhesive composition, adhesive, adhesive sheet, and display that can effectively prevent and inhibit migration. [Means for Solving the Problem]

To achieve the above objectives, first, the present invention provides an adhesive composition characterized by comprising: a (meth)acrylate polymer (A); a rust repellent (B); and a long-chain alkylamine (C) (Invention 1).

According to the aforementioned invention (Invention 1), the coexistence of the rust preventer (B) and the long-chain alkylamine (C) facilitates the stable presence of the rust preventer (B) on the surface of the adhesive layer formed from the adhesive composition. Consequently, when the adhesive layer contacts the electrodes, it prevents and suppresses electrode dissolution at the positive electrode and dendritic crystal formation at the negative electrode. This effectively prevents and suppresses electrode migration, thereby suppressing changes in the resistance of electrodes composed of metals or metal oxides.

In the above invention (Invention 1), it is preferred that the silane compound (D) contains alkoxysilyl groups at both ends (Invention 2).

In the above inventions (Inventions 1 and 2), it is preferred that an alkanediol (E) is contained (Invention 3).

In the above inventions (Inventions 1 to 3), the rustproofing agent (B) is preferably an azo type (Invention 4).

In the above inventions (Inventions 1 to 4), the long-chain alkylamine (C) is preferably a tertiary amine (Invention 5).

In the above inventions (Inventions 1 to 5), it is preferred that a bridging agent (F) is contained (Invention 6).

In the above inventions (Inventions 1 to 6), it is preferred that the (meth)acrylate polymer (A) does not contain a carboxyl group-containing monomer as a monomer unit constituting the polymer (Invention 7).

In the above inventions (Inventions 1 to 7), the (meth)acrylate polymer (A) preferably contains 6% by mass or more and 35% by mass or less of a hydroxyl group-containing monomer as a monomer unit constituting the polymer (Invention 8).

The above inventions (Inventions 1 to 8) may also contain an ultraviolet absorber (Invention 9).

In the above inventions (Inventions 1 to 9), the adhesive composition is preferably used to form an adhesive for contacting an electrode composed of metal or metal oxide (Invention 10).

Second, the present invention provides an adhesive (Invention 11) formed by bridging the above-mentioned adhesive compositions (Inventions 1 to 10).

Third, the present invention provides an adhesive sheet comprising: two release sheets; and an adhesive layer sandwiched between the release sheets in a manner that contacts the release surfaces of the two release sheets, wherein the adhesive layer is composed of the adhesive (Invention 11) (Invention 12).

Fourthly, the present invention provides a display comprising: a first display component; a second display component; and an adhesive layer for bonding the first display component and the second display component to each other, wherein the first display component and/or the second display component has an electrode composed of a metal or metal oxide on at least the bonding side, and the adhesive layer is composed of the above-mentioned adhesive (Invention 11) (Invention 13). [Effects of the Invention]

The adhesive composition, adhesive, adhesive sheet, and display of the present invention can effectively prevent and inhibit migration.

The following describes embodiments of the present invention. [Adhesive Composition] The adhesive composition of this embodiment (hereinafter sometimes referred to as "adhesive composition P") comprises: a (meth)acrylate polymer (A); a rust repellent (B); and a long-chain alkylamine (C). Preferably, it further comprises: a silane compound having alkoxysilyl groups at both ends (D); an alkanediol (E); and a crosslinking agent (F). In this specification, the term "(meth)acrylate" refers to both acrylate and methacrylate. Other similar terms apply. Furthermore, the term "polymer" also includes the term "copolymer."

The adhesive composition P of this embodiment is preferably used to form an adhesive for contacting electrodes composed of metals or metal oxides. Because the adhesive composition P contains the aforementioned components, the adhesive obtained from the adhesive composition P, when in contact with the electrodes, can prevent and suppress electrode dissolution at the positive electrode and prevent and suppress the formation of dendritic crystals at the negative electrode. In other words, electrode migration can be effectively prevented and suppressed (this effect is sometimes referred to as a "migration prevention effect"), thereby suppressing changes in the resistance value of electrodes composed of metals or metal oxides. Furthermore, by effectively preventing and suppressing migration, the adhesive can also prevent electrode disconnection and short circuits, for example, when used with miniaturized and narrowly pitched electrodes. In particular, when the electrodes are electrodes of a touch panel, driving failure of the touch panel due to disconnection or short circuit of the electrodes can be prevented.

Examples of the electrodes include metal electrodes (including grid and lattice-shaped ones) made of copper, copper alloys, silver, and silver alloys, and transparent conductive films (including patterned ones) made of tin-doped indium oxide (ITO). Among these electrodes, metal electrodes primarily composed of non-oxidized metals are preferred. Specifically, metal electrodes composed of copper, copper alloys, silver, or silver alloys are preferred, with silver or silver alloys being particularly preferred. Preferred silver alloys include, for example, silver with palladium and copper added thereto. Unoxidized metals have a higher tendency to ionize than metal oxides such as ITO. However, the adhesive obtained from the adhesive composition P according to this embodiment can effectively prevent electrode disconnection and short circuits even in this case.

The reason for this effect is unclear, but it is speculated as follows. In the adhesive layer obtained from the adhesive composition P, the rust repellent (B) and the long-chain alkylamine (C) have very small molecular structures compared to the large molecular structure of the (meth)acrylate polymer (A) bridge, and both tend to segregate on the surface of the adhesive layer. Furthermore, the long-chain alkylamine (C) is appropriately distributed on the surface of the adhesive layer, making it easier for the rust repellent (B) to be more stably distributed on the surface side of the adhesive layer or around the long-chain alkylamine (C) than the long-chain alkylamine (C). Therefore, in the adhesive layer obtained from the adhesive composition P, the rust repellent (B) is more likely to be stably present on the adhesive layer surface than in an adhesive layer without the long-chain alkylamine (C). Furthermore, since the rust repellent (B) has a lower molecular weight than the long-chain alkylamine (C), it is estimated that the amount of rust repellent (B) segregating to the adhesive layer surface is greater, and the ratio of rust repellent present on the surface is also higher. In other words, the coexistence of the rust repellent (B) and the long-chain alkylamine (C) facilitates the rust repellent (B) to be stably present on the adhesive layer surface, making it easier for the rust repellent (B) to effectively exert its effect. It is estimated that this adhesive layer can thus exhibit an excellent migration prevention effect.

Furthermore, the adhesive obtained from the adhesive composition P according to this embodiment can be an active energy ray-hardening adhesive that hardens upon irradiation with active energy rays, or an active energy ray-non-hardening adhesive that does not harden upon irradiation with active energy rays. In the case of an active energy ray-hardening adhesive, the adhesive composition P preferably further contains an active energy ray-hardening component (G).

(1) Components (1-1) (Meth)acrylate Polymer (A) In the (meth)acrylate polymer (A) of this embodiment, it is preferred that a monomer unit constituting the polymer include a reactive functional group-containing monomer having a reactive group in the molecule. The reactive functional group-containing monomer reacts with the crosslinking agent (F) via the reactive functional group derived from the reactive functional group-containing monomer to form a bridge structure (three-dimensional lattice structure), thereby obtaining an adhesive having a predetermined cohesive force.

In the (meth)acrylate polymer (A), as a reactive functional group-containing monomer contained in a monomer unit constituting the polymer, suitable examples include monomers having a hydroxyl group in the molecule (hydroxyl-containing monomer), monomers having a carboxyl group in the molecule (carboxyl-containing monomer), and monomers having an amino group in the molecule (amino-containing monomer). These reactive functional group-containing monomers may be used alone or in combination of two or more.

Among the above-mentioned reactive functional group-containing monomers, hydroxyl group-containing monomers are particularly preferred because they have excellent reactivity with the bridger (F) and have little adverse effect on the electrode.

Examples of hydroxyl-containing monomers 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 these, from the perspective of reactivity with the crosslinking agent (F), 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are preferred, 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate are more preferred, and 2-hydroxyethyl acrylate is particularly preferred. These monomers may be used alone or in combination of two or more.

The (meth)acrylate polymer (A) preferably contains 6% by mass or more of a reactive functional group-containing monomer (particularly a hydroxyl group-containing monomer) as monomer units constituting the polymer, particularly preferably 9% by mass or more, and further preferably 12% by mass or more. Furthermore, the (meth)acrylate polymer (A) preferably contains 35% by mass or less of a reactive functional group-containing monomer (particularly a hydroxyl group-containing monomer) as monomer units constituting the polymer, particularly preferably 30% by mass or less, and further preferably 25% by mass.

The (meth)acrylate polymer (A) containing the reactive functional group-containing monomer as a monomer unit in the aforementioned amount can achieve a good balance between the adhesive strength and cohesive strength of the resulting adhesive. In particular, when the reactive functional group-containing monomer is a hydroxyl group-containing monomer, the (meth)acrylate polymer (A) containing the hydroxyl group-containing monomer as a monomer unit in the aforementioned amount can retain a predetermined amount of hydrophilic hydroxyl groups in the resulting adhesive. This allows the hydroxyl groups to capture moisture even in the presence of water, thereby suppressing its infiltration into the electrode adjacent to the adhesive layer and further enhancing the migration prevention effect.

The (meth)acrylate polymer (A) preferably does not contain carboxyl-containing monomers as monomer units constituting the polymer. Carboxyl groups are acidic components and may corrode the electrode in contact with the adhesive, causing a change in resistance. However, by not containing carboxyl-containing monomers, electrode corrosion can be prevented, effectively preventing and suppressing changes in resistance. However, the phrase "does not contain carboxyl-containing monomers" as used above means that carboxyl-containing monomers may be contained to the extent that the electrode in contact with the resulting adhesive is not adversely affected. Specifically, the (meth)acrylate polymer (A) may contain carboxyl-containing monomers in an amount of 0.1% by mass or less, preferably 0.01% by mass or less, and more preferably 0.001% by mass or less, per monomer unit.

Furthermore, the (meth)acrylate polymer (A) preferably contains an alkyl (meth)acrylate as a monomer unit constituting the polymer. This can exhibit good adhesion.

In particular, the (meth)acrylate polymer (A) preferably contains, as monomer units constituting the polymer, in addition to the above-mentioned reactive functional group-containing monomer, an alkyl (meth)acrylate having a homopolymer glass transition temperature (Tg) of 0°C or lower and an alkyl group with 2 to 20 carbon atoms, and a monomer having a homopolymer glass transition temperature (Tg) exceeding 0°C.

The (meth)acrylate polymer (A) exhibits excellent adhesion when it contains, as monomer units constituting the polymer, an alkyl (meth)acrylate having a homopolymer glass transition temperature (Tg) of 0°C or lower and an alkyl group with 2 to 20 carbon atoms (hereinafter sometimes referred to as a "low-Tg alkyl acrylate"). From this perspective, the (meth)acrylate polymer (A) preferably contains, as monomer units constituting the polymer, 30% by mass or greater of the low-Tg alkyl acrylate, more preferably 40% by mass or greater, particularly preferably 50% by mass or greater, and even more preferably 60% by mass or greater. Furthermore, the upper limit of the content of the low-Tg alkyl acrylate in the (meth)acrylate polymer (A) as a monomer unit constituting the polymer is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less. When the upper limit of the content of the low Tg alkyl acrylate is within the above range, an appropriate amount of other monomer components can be introduced into the (meth)acrylate polymer (A).

Examples of low-Tg alkyl acrylates include ethyl acrylate (Tg-20°C), n-butyl acrylate (Tg-55°C), isobutyl acrylate (Tg-26°C), n-octyl acrylate (Tg-65°C), isooctyl acrylate (Tg-58°C), 2-ethylhexyl acrylate (Tg-70°C), 2-ethylhexyl methacrylate (Tg-10°C), isononyl acrylate (Tg-58°C), isodecyl acrylate (Tg-60°C), isodecyl methacrylate (Tg-41°C), n-lauryl acrylate (Tg-23°C), n-lauryl methacrylate (Tg-65°C), tridecyl acrylate (Tg-55°C), tridecyl methacrylate (Tg-40°C), and isostearyl acrylate (Tg-18°C). Among these, low-Tg alkyl acrylates are preferably homopolymers with a Tg of -40°C or lower, and particularly preferably -50°C or lower, from the perspective of more effectively imparting adhesion. Specifically, n-butyl acrylate and 2-ethylhexyl acrylate are particularly preferred, and 2-ethylhexyl acrylate is even more preferred from the perspective of inhibiting migration. These may be used alone or in combination of two or more. Furthermore, the alkyl group in the alkyl (meth)acrylate having an alkyl group having 2 to 20 carbon atoms refers to a linear, branched, or cyclic alkyl group.

Furthermore, from the perspective of suppressing migration by enhancing the hydrophobicity of the resulting adhesive layer, the low-Tg alkyl acrylate is preferably, at least in part, an alkyl (meth)acrylate having an alkyl group with 5 or more carbon atoms, and more preferably an alkyl (meth)acrylate having an alkyl group with 7 or more carbon atoms. Specifically, 2-ethylhexyl acrylate is particularly preferred. Furthermore, from the perspective of suppressing migration, the proportion of alkyl (meth)acrylate having an alkyl group with 5 or more carbon atoms (preferably 7 or more) in the total low-Tg alkyl acrylate 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.

Furthermore, by containing a monomer (hereinafter sometimes referred to as a "hard monomer") whose homopolymer glass transition temperature (Tg) exceeds 0°C as a monomer unit constituting the (meth)acrylate polymer (A), the resulting adhesive can be easily made to possess appropriate cohesive strength and adhesion. This makes it easier for the resulting adhesive layer to suppress abnormalities such as lifting or peeling at the adherend interface, even after endurance testing.

As the hard monomer, methyl acrylate (Tg 10°C), methyl methacrylate (Tg 105°C), ethyl methacrylate (Tg 65°C), n-butyl methacrylate (Tg 20°C), isobutyl methacrylate (Tg 48°C), tert-butyl methacrylate (Tg 107°C), n-stearyl acrylate (Tg 30°C), n-stearyl methacrylate (Tg 38°C), cyclohexyl acrylate (Tg 15°C), cyclohexyl methacrylate (Tg 66°C), phenoxyethyl acrylate (Tg 5°C), methacrylate (Tg 5°C), methyl methacrylate (Tg 6 ... From the perspective of compatibility, acrylic monomers such as phenoxyethyl acrylate (Tg 54°C), benzyl methacrylate (Tg 54°C), isoborneol acrylate (Tg 94°C), isoborneol methacrylate (Tg 180°C), acrylamide (Tg 145°C), adamantyl acrylate (Tg 115°C), adamantyl methacrylate (Tg 141°C), dimethylacrylamide (Tg 89°C), acrylamide (Tg 165°C), vinyl acetate (Tg 32°C), and styrene (Tg 80°C) can be more effectively selected. These monomers can be used alone or in combination of two or more.

In particular, from the perspective of imparting good cohesion and adhesion to the resulting adhesive and effectively suppressing abnormalities such as lifting and peeling at the adherend interface, the glass transition temperature (Tg) of the hard monomer is preferably 60°C or higher, and particularly preferably 90°C or higher. Furthermore, considering compatibility and copolymerizability with other monomers constituting the (meth)acrylate polymer (A), the glass transition temperature (Tg) of the hard monomer is preferably 250°C or lower, more preferably 200°C or lower, and particularly preferably 150°C or lower.

Among the above-mentioned hard monomers, from the perspective of further enhancing the performance of the hard monomer while preventing adverse effects on other properties such as compatibility with other components, it is preferred that the hard monomer contain at least one selected from the group consisting of methyl methacrylate, isoborneol acrylate, and acrylamide. In particular, it is preferred to use methyl methacrylate alone or to use isoborneol acrylate and acrylamide in combination.

From the viewpoint of imparting good cohesive force and adhesion to the resulting adhesive, the hard monomer is preferably contained in the (meth)acrylate polymer (A) as a monomer constituting the polymer in an amount of 5% by mass or more, more preferably 10% by mass or more, and particularly preferably 15% by mass or more.

Furthermore, the hard monomer preferably contains 50% by mass or less, more preferably 40% by mass or less, and particularly preferably 30% by mass or less of the monomer constituting the polymer, from the viewpoint of achieving excellent compatibility of the obtained (meth)acrylate polymer (A) with other components.

The (meth)acrylate polymer (A) may contain other monomers as monomer units constituting the polymer, if desired. These other monomers are preferably monomers that do not contain reactive functional groups, so as not to hinder the effects of the monomer containing the reactive functional group. Examples of these other monomers include alkoxyalkyl (meth)acrylates such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate. These monomers may be used alone or in combination of two or more.

The (meth)acrylate polymer (A) is preferably a solution polymer obtained by solution polymerization. This facilitates obtaining a high molecular weight polymer, thereby providing an adhesive with excellent durability.

The polymerization state of the (meth)acrylate polymer (A) may be a random copolymer or a block copolymer.

The lower limit of the weight-average molecular weight of the (meth)acrylate polymer (A) is preferably 200,000 or greater, particularly preferably 300,000 or greater, and even more preferably 400,000 or greater. A weight-average molecular weight lower limit of the (meth)acrylate polymer (A) above this value improves the durability of the adhesive and allows the rust preventer (B) and the long-chain alkylamine (C) to segregate stably on the surface of the adhesive layer, facilitating their coexistence. The weight-average molecular weights used in this specification are values calculated in terms of standard polystyrene as measured by gel permeation chromatography (GPC).

The upper limit of the weight average molecular weight of the (meth)acrylate polymer (A) is preferably 1.2 million or less, particularly preferably 900,000 or less, and even more preferably 750,000 or less. When the upper limit of the weight average molecular weight of the (meth)acrylate polymer (A) is within the above range, the resulting adhesive exhibits good adhesion.

In the adhesive composition P, the (meth)acrylate polymer (A) may be used alone or in combination of two or more.

(1-2) Rust Repellent (B) In this embodiment, the rust repellent (B) preferably coexists well with the long-chain alkylamine (C) described below on the surface of the adhesive layer. Such a rust repellent (B) can be readily and stably present on the surface of the adhesive layer, effectively exerting its effect and contributing to the migration prevention effect. Examples of such rust repellents (B) include azoles such as azole compounds, triazole compounds, benzotriazole compounds, thiazole compounds, benzothiazole compounds, imidazole compounds, and benzimidazole compounds, as well as phosphorus compounds and nitrite compounds. Among these, azoles, particularly benzotriazole compounds, are preferred because they readily segregate with the long-chain alkylamine (C) on the surface of the adhesive layer, providing excellent migration prevention. Rust repellent (B) can be used alone or in combination of two or more.

Examples of benzotriazole compounds include 1H-benzotriazole, 1H-tolyltriazole, 1-[N,N-bis(2-ethylhexyl)aminomethyl]benzotriazole, 1-[N,N-bis(2-ethylhexyl)aminomethyl]methylbenzotriazole, carboxybenzotriazole, and 2,2'-[[(methyl 1H-benzotriazol-1-yl)methyl]imino]bisethanol. Among these, 1H-benzotriazole, 1H-tolyltriazole, 1-[N,N-bis(2-ethylhexyl)aminomethyl]benzotriazole, and 1-[N,N-bis(2-ethylhexyl)aminomethyl]methylbenzotriazole are preferred due to their good coexistence with the long-chain alkylamine (C). These compounds can more effectively suppress the occurrence of migration.

The content of the rust repellent (B) in the adhesive composition P is preferably 0.01 parts by mass or more, more preferably 0.08 parts by mass or more, particularly preferably 0.12 parts by mass or more, and even more preferably 0.15 parts by mass or more, per 100 parts by mass of the (meth)acrylate polymer (A). This facilitates moderate segregation on the surface of the resulting adhesive layer, resulting in a more effective migration prevention effect. Furthermore, the above content is preferably 2 parts by mass or less, more preferably 1 part by mass or less, particularly preferably 0.5 parts by mass or less, and even more preferably 0.2 parts by mass or less. This allows the long-chain alkylamine (C) and the rust repellent (B) to coexist well on the surface of the resulting adhesive layer, exerting a good migration prevention effect while maintaining good adhesion.

(1-3) Long-chain alkylamine (C) The long-chain alkylamine (C) in this embodiment is an amine containing a long-chain alkyl group in its molecule. The long-chain alkyl group is preferably linear, but may also have a branched or cyclic structure. The long-chain alkyl group preferably has 10 or more carbon atoms, more preferably 12 or more carbon atoms, and particularly preferably 14 or more carbon atoms. Furthermore, the carbon atoms are preferably 24 or less carbon atoms, more preferably 22 or less carbon atoms, particularly preferably 20 or less carbon atoms, and even more preferably 18 or less carbon atoms. Such a long-chain alkylamine (C) readily segregates on the surface of the adhesive layer along with the rust repellent (B), allowing the rust repellent (B) to be stably present on the surface. In this way, the long-chain alkylamine (C) and the rust inhibitor (B) work together to achieve an excellent migration prevention effect.

In this embodiment, the long-chain alkylamine (C) can be a primary amine, a secondary amine, or a tertiary amine, with tertiary amines being preferred. By using tertiary amines, the resulting adhesive layer and release sheet can maintain a low peeling force, resulting in excellent operability during use.

Furthermore, the long-chain alkylamine (C) of this embodiment preferably has a hydroxyl group at the end. The hydroxyl group inhibits water from penetrating into the electrode adjacent to the adhesive layer, thereby further improving the migration prevention effect.

Furthermore, the long-chain alkylamine (C) in this embodiment preferably contains an oxyethylene structure, and particularly preferably contains a polyoxyethylene structure. That is, the long-chain alkylamine (C) in this embodiment is preferably an oxyethylene long-chain alkylamine, and particularly preferably a polyoxyethylene long-chain alkylamine. Hereinafter, oxyethylene long-chain alkylamines and polyoxyethylene long-chain alkylamines may be collectively referred to as "(poly)oxyethylene long-chain alkylamines."

The (poly)oxyethylene long chain alkylamine is preferably a compound represented by the following general formula (c). [Chemistry 1]

In general formula (c), R represents a long-chain alkyl group. Furthermore, m and n are each independently an integer greater than or equal to 1, preferably greater than or equal to 2, and more preferably greater than or equal to 5. Furthermore, m and n are each independently preferably less than or equal to 15, more preferably less than or equal to 12, and particularly preferably less than or equal to 10. This facilitates satisfying the values of m and n described below.

In general formula (c), the sum of the values of m and n is an integer greater than or equal to 2. The lower limit of the sum of the values of m and n is preferably greater than or equal to 4, more preferably greater than or equal to 8, and particularly preferably greater than or equal to 12. The upper limit of the sum of the values of m and n is preferably less than or equal to 30, more preferably less than or equal to 24, particularly preferably less than or equal to 20, and even more preferably less than or equal to 15. Long-chain alkylamines (C) having a sum of the values of m and n within the above range tend to segregate on the surface of the adhesive layer together with the rust preventer (B), allowing the rust preventer (B) to be stably present on the surface.

The weight-average molecular weight of the long-chain alkylamine (C) is preferably 250 or greater, more preferably 350 or greater, particularly preferably 500 or greater, and even more preferably 700 or greater. Furthermore, the weight-average molecular weight of the long-chain alkylamine (C) is preferably 1400 or less, more preferably 1300 or less, particularly preferably 1200 or less, and even more preferably 1000 or less. By setting the weight-average molecular weight of the long-chain alkylamine (C) within the above-mentioned range, the long-chain alkylamine (C) is easily segregated on the surface of the adhesive layer along with the rust preventer (B), allowing the rust preventer (B) to be stably present on the surface, thereby enhancing the migration prevention effect.

The content of the long-chain alkylamine (C) in the adhesive composition P is preferably 0.01 parts by mass or greater, more preferably 0.08 parts by mass or greater, particularly preferably 0.12 parts by mass or greater, and even more preferably 0.15 parts by mass or greater, per 100 parts by mass of the (meth)acrylate polymer (A). This facilitates the segregation of the long-chain alkylamine (C) along with the rust preventer (B) on the surface of the adhesive layer, allowing the rust preventer (B) to be stably present on the surface and achieving a more effective migration prevention effect. Furthermore, the content is preferably 2 parts by mass or less, more preferably 1 part by mass or less, particularly preferably 0.5 parts by mass or less, and even more preferably 0.2 parts by mass or less. This allows the long-chain alkylamine (C) and the rust repellent (B) to coexist well on the surface of the resulting adhesive layer, exerting a good migration prevention effect while maintaining good adhesion.

(1-4) Silane compound (D)

The adhesive composition P of this embodiment contains a silane compound (D) with alkoxysilyl groups at both ends, which further enhances the migration prevention effect. This is presumably because the alkoxysilyl groups in the silane compound (D) inhibit moisture from penetrating into the electrode adjacent to the resulting adhesive layer.

The silane compound (D) is an organic silicon compound having alkoxysilyl groups at both ends, preferably a compound represented by the following general formula (I).

[Chemistry 2] In the formula, ^R1 is a divalent hydroxyl group which may have a nitrogen atom. In the formula, ^R2 to ^R7 are each independently an alkyl group.

The divalent hydroxyl group in ^R1 preferably has 1 to 10 carbon atoms, particularly 3 to 9, and even more preferably 4 to 8. From the perspective of preventing migration to metal electrodes (particularly silver electrodes), 5 to 7 is the most preferred. Furthermore, the hydroxyl group is preferably a saturated hydroxyl group, and especially a chain saturated hydroxyl group. Furthermore, the hydroxyl group preferably includes an alkylene group, and especially an alkylene group. The alkylene group preferably has 1 to 10 carbon atoms, particularly 3 to 9, and even more preferably 4 to 8. From the perspective of preventing migration to metal electrodes (particularly silver electrodes), 5 to 7 is the most preferred.

When ^R1 contains a nitrogen atom, the nitrogen atom may be present in the side chain of the hydroxyl group, but is preferably present in the main chain of the hydroxyl group. When ^R1 contains a nitrogen atom, the number of nitrogen atoms contained in ^R1 is preferably 1 to 5, particularly 2 to 3. The nitrogen atom is preferably an amino group or an amide group, particularly an amino group, and is preferably present in the main chain of the hydroxyl group as a diamine or tertiary amine.

When ^R1 contains a nitrogen atom, a skeleton comprising ^R1 -(CH) _m -NH- is preferred, a skeleton comprising -(CH) _m -NH-(CH) _n- is more preferred, a skeleton comprising -(CH) _m -NH-(CH) _n -NH- is particularly preferred, and a skeleton comprising -(CH) _m -NH-(CH) _{n -} NH- is even more preferred. The above-mentioned m, n, and p are positive integers, preferably 1 to 5, and particularly preferably 2 to 4.

It is preferred that the main chain of ^R1 not contain sulfur atoms. If sulfur atoms are present in the main chain, metal sulfides are likely to form at the interface between the adhesive and the electrode composed of metal (particularly silver) or metal oxide (particularly ITO) under durability testing conditions. This may hinder the aforementioned migration prevention effect.

The carbon number of the alkyl groups R ² to R ⁷ is preferably 1 to 6, particularly preferably 1 to 4, further preferably 1 to 2, and most preferably 1. Furthermore, R ² to R ⁷ are preferably the same alkyl group, and most preferably methyl groups.

The content of the silane compound (D) in the adhesive composition P is preferably 0.01 parts by mass or greater, more preferably 0.1 parts by mass or greater, particularly preferably 0.16 parts by mass or greater, and even more preferably 0.22 parts by mass or greater, per 100 parts by mass of the (meth)acrylate polymer (A). Furthermore, the upper limit of this content is preferably 2 parts by mass or less, particularly preferably 1 part by mass or less, and even more preferably 0.5 parts by mass or less. By maintaining the content of the silane compound (D) within this range, the silane compound (D) can effectively exert its effects, resulting in a more excellent migration prevention effect.

(1-5) Alkanediol (E) The adhesive composition P of this embodiment contains an alkanediol (E), which further enhances the migration prevention effect. This is presumably because the hydroxyl groups in the alkanediol (E) inhibit moisture from penetrating into the electrode adjacent to the resulting adhesive layer.

The alkanediol (E) is not particularly limited as long as it can exhibit the above-mentioned effects, and good examples include ethylene glycol, propylene glycol, butylene glycol, glycerol, and alkanediol monoalkyl ethers. Among them, alkanediol monoalkyl ethers are particularly excellent in the migration prevention effect.

The number of carbon atoms in the alkylene group of the alkanediol in the alkanediol monoalkyl ether is preferably 1 or more, more preferably 2 or more, and particularly preferably 3 or more. Furthermore, the number of carbon atoms in the alkylene group is preferably 10 or less, more preferably 8 or less, and particularly preferably 6 or less. On the other hand, the number of carbon atoms in the alkylene group of the monoalkyl ether in the alkanediol monoalkyl ether is preferably 1 or more. Furthermore, the number of carbon atoms in the alkylene group is preferably 8 or less, more preferably 6 or less, particularly preferably 4 or less, and even more preferably 3 or less.

Specific examples of the alkanediol monoalkyl ether include ethylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, polyethylene glycol monomethyl ether, polyethylene glycol monopropyl ether, and polyethylene glycol monobutyl ether; and propylene glycol monoalkyl ethers such as propylene glycol monomethyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monobutyl ether, polypropylene glycol monomethyl ether, and polypropylene glycol monobutyl ether. Among these, propylene glycol monoalkyl ethers are preferred, with dipropylene glycol monoalkyl ether being particularly preferred, and dipropylene glycol monomethyl ether being even more preferred. The alkanediol (E) may be used alone or in combination of two or more.

The content of the alkanediol (E) in the adhesive composition P is preferably 0.01 parts by mass or greater, more preferably 0.1 parts by mass or greater, particularly preferably 0.4 parts by mass or greater, and even more preferably 0.8 parts by mass or greater, per 100 parts by mass of the (meth)acrylate polymer (A). Furthermore, the upper limit of this content is preferably 5 parts by mass or less, preferably 3 parts by mass or less, particularly preferably 2 parts by mass or less, and even more preferably 1.5 parts by mass or less. By keeping the content of the alkanediol (E) within the above range, the effects of the alkanediol (E) can be effectively exerted, resulting in a more excellent migration prevention effect.

(1-6) Bridging Agent (F) The adhesive composition P preferably contains a bridging agent (F). By including the bridging agent (F), the adhesive composition P bridges the (meth)acrylate polymer (A) to form a three-dimensional lattice structure, thereby enhancing the cohesive strength and durability of the resulting adhesive.

The bridger (F) may be any bridger capable of reacting with the reactive group of the (meth)acrylate polymer (A), and examples thereof include isocyanate bridgers, epoxy bridgers, amine bridgers, melamine bridgers, aziridine bridgers, hydrazine bridgers, aldehyde bridgers, oxazoline bridgers, metal alkoxide bridgers, metal chelate bridgers, metal salt bridgers, and ammonium salt bridgers. When the (meth)acrylate polymer (A) contains a hydroxyl group-containing monomer as a monomer unit constituting the polymer, it is preferred to use an isocyanate-based crosslinking agent that has excellent reactivity with the hydroxyl group. Furthermore, the crosslinking agent (F) may be used alone or in combination of two or more.

Isocyanate-based crosslinking agents include at least a polyisocyanate compound. Examples of polyisocyanate compounds include aromatic polyisocyanates such as toluene diisocyanate, diphenylmethane diisocyanate, and xylene diisocyanate; aliphatic polyisocyanates such as hexamethylene isocyanate; alicyclic polyisocyanates such as isophorone diisocyanate and hydrodiphenylmethane diisocyanate; and diurea and isocyanurate forms of these compounds, as well as adducts of these compounds with compounds containing low-molecular-weight active hydrogen atoms, such as ethylene glycol, propylene glycol, neopentyl glycol, trihydroxymethylpropane, and castor oil. Among them, trihydroxymethylpropane-modified aromatic polyisocyanates, particularly trihydroxymethylpropane-modified toluene diisocyanate, are preferred from the viewpoint of reactivity with hydroxyl groups.

The content of the crosslinking agent (F) in the adhesive composition P is preferably 0.001 parts by mass or more, particularly 0.01 parts by mass or more, and more preferably 0.1 parts by mass or more, per 100 parts by mass of the (meth)acrylate polymer (A). From the perspective of facilitating good segregation of the rust preventer (B) and the long-chain alkylamine (C) on the surface of the adhesive layer, the content is preferably 0.3 parts by mass or more, particularly 0.6 parts by mass or more. Furthermore, the upper limit of the above content is preferably 10 parts by mass or less, particularly 5 parts by mass or less, and more preferably 1 part by mass or less. From the perspective of improving adhesion, the content is preferably 0.5 parts by mass or less. By adjusting the content of the crosslinking agent (F) within the above range, the cohesive force of the resulting adhesive is improved, and an adhesive having excellent adhesion can be obtained.

(1-7) Active Energy Ray-Curing Component (G) When the adhesive obtained from the adhesive composition P of this embodiment is made into an active energy ray-curing adhesive, the adhesive composition P preferably contains an active energy ray-curing component (G). By including the active energy ray-curing component (G) in the adhesive composition P, the adhesive obtained by bridging (thermal bridging) the adhesive composition P becomes an active energy ray-curing adhesive. In this active energy ray-curing adhesive, it is presumed that the active energy ray-curing component (G) polymerizes with the adhesive composition (G) during curing by irradiation with active energy rays after bonding to an adherend, and the polymerized active energy ray-curing component (G) and the (meth)acrylate polymer (A) form a bridging structure (three-dimensional lattice structure) entangled. Adhesives with this high-dimensional structure exhibit high cohesion and film strength, resulting in superior durability.

The active energy ray-curable component (G) is not particularly limited as long as it can be cured by irradiation with active energy rays to achieve the aforementioned effects. It can be any monomer, oligomer, or polymer, or a mixture thereof. Preferred examples include multifunctional acrylate monomers, which can produce adhesives with superior durability.

Examples of the multifunctional acrylate monomer include 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, neopentyl glycol adipate di(meth)acrylate, hydroxytrimethylacetic acid neopentyl glycol di(meth)acrylate, dicyclopentyl di(meth)acrylate, caprolactone-modified dicyclopentenyl di(meth)acrylate, ethylene oxide-modified phosphoric acid di(meth)acrylate, di(acryloyloxyethyl) isocyanurate, allyl cyclohexyl di(meth)acrylate, ethoxylated bisphenol A diacrylate, and 9,9-bis[4-(2-acryloyloxyethoxy)phenyl]fluorene. 2-functional type; trihydroxymethylpropane tri(meth)acrylate, dipentatriol tri(meth)acrylate, propionic acid-modified dipentatriol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propylene oxide-modified trihydroxymethylpropane tri(meth)acrylate, tris(acryloyloxyethyl)isocyanurate, ε-caprolactone-modified tris(2-(meth)acryloyloxyethyl)isocyanurate, etc.; quadrifunctional type such as diglycerol tetra(meth)acrylate and pentaerythritol tetra(meth)acrylate; pentafunctional type such as propionic acid-modified dipentatriol penta(meth)acrylate; hexafunctional type such as dipentatriol hexa(meth)acrylate and caprolactone-modified dipentatriol hexa(meth)acrylate, etc. Among the above, polyfunctional acrylate monomers containing an isocyanurate structure in the molecule, such as bis(acryloxyethyl)isocyanurate, tris(acryloxyethyl)isocyanurate, and ε-caprolactone-modified tris(2-(meth)acryloxyethyl)isocyanurate, are preferred from the viewpoint of imparting good cohesive strength and adhesion to the resulting adhesive and effectively suppressing abnormalities such as lifting and peeling at the interface with the adherend. Polyfunctional acrylate monomers containing an isocyanurate structure in the molecule, such as bis(acryloxyethyl)isocyanurate, tris(acryloxyethyl)isocyanurate, and ε-caprolactone-modified tris(2-(meth)acryloxyethyl)isocyanurate, are more preferred. Polyfunctional acrylate monomers containing a trifunctional or higher functionality and containing an isocyanurate structure in the molecule are more preferred, and ε-caprolactone-modified tris(2-(meth)acryloxyethyl)isocyanurate is particularly preferred. These monomers may be used alone or in combination of two or more. Furthermore, from the viewpoint of compatibility with the (meth)acrylate polymer (A), the molecular weight of the polyfunctional acrylate monomer is preferably 1,000 or less.

The active energy ray-curable component (G) may also be an active energy ray-curable acrylate oligomer. Examples of such acrylate oligomers include polyester acrylates, epoxy acrylates, urethane acrylates, polyether acrylates, polybutadiene acrylates, and silicone acrylates.

The weight average molecular weight of the acrylate 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 alone or in combination of two or more.

Alternatively, an adduct acrylate polymer having a (meth)acryloyl group introduced into the side chain may be used as the active energy ray-curable component (G). Such an adduct acrylate polymer is obtained by reacting a compound having a group reactive with the (meth)acryloyl group and the bridging functional group with a portion of the bridging functional groups of the copolymer, using a copolymer of a (meth)acrylate and a monomer having a bridging functional group within the molecule.

The weight average molecular weight of the adduct acrylate polymer is preferably about 50,000 to 900,000, and particularly preferably about 100,000 to 500,000.

The active energy ray-curable component (G) may be selected from the above-mentioned multifunctional acrylate monomers, acrylate oligomers and adduct acrylate polymers, or may be used in combination of two or more thereof, or may be used in combination with other active energy ray-curable components.

When the adhesive composition P contains an active energy ray-curable component (G), the content of the active energy ray-curable component (G) is preferably 2 parts by mass or greater, more preferably 3 parts by mass or greater, and particularly preferably 4 parts by mass or greater, per 100 parts by mass of the (meth)acrylate polymer (A). Furthermore, 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 even more preferably 6 parts by mass or less. By adjusting the content of the active energy ray-curable component (G) within the above range, the adhesive strength of the adhesive after active energy ray curing can be enhanced, and the durability of the adhesive can also be improved.

(1-8) Photopolymerization Initiator (H) When the adhesive obtained from the adhesive composition P according to this embodiment is used as an active energy ray-curable adhesive, and when ultraviolet light is used as the active energy ray, the adhesive composition P preferably further contains a photopolymerization initiator (H). The inclusion of such a photopolymerization initiator (H) allows the active energy ray-curable component (G) to be efficiently polymerized, and also reduces the polymerization and curing time and the active energy ray exposure dose.

Examples of such a photopolymerization initiator (H) include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropane-1-one, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-oxolinyl-propane-1-one, and 4-(2-hydroxyethoxy)phenyl-2-(hydroxy-2-propyl)ketone. , benzophenone, p-phenylbenzophenone, 4,4-diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, 2-methylthiazolone, 2-ethylthiazolone, 2-chlorothiazolone, 2,4-dimethylthiazolone, 2,4-diethylthiazolone, benzyl dimethyl ketal, acetophenone dimethyl ketal, p-dimethylaminobenzoate, oligo[2-hydroxy-2-methyl-1[4-(1-methylvinyl)phenyl]propanone], 2,4,6-trimethylbenzyl-diphenyl-phosphine oxide, and the like. These may be used alone or in combination of two or more.

When the adhesive composition P contains an active energy ray-curable component (G) and a photopolymerization initiator (H), the content of the photopolymerization initiator (H) is preferably 0.1 parts by mass or more, particularly 1 part by mass or more, and further preferably 5 parts by mass or more per 100 parts by mass of the active energy ray-curable component (G). Furthermore, the upper limit of this content is preferably 30 parts by mass or less, particularly 20 parts by mass or less, and further preferably 15 parts by mass or less. By adjusting the content of the photopolymerization initiator (H) within this range, the adhesive strength of the adhesive after active energy ray curing can be enhanced, and the durability of the adhesive can also be improved.

(1-9) Various Additives Additives commonly used in acrylic adhesives, such as UV absorbers, silane coupling agents, antistatic agents, adhesion promoters, oxidation inhibitors, light stabilizers, softeners, fillers, and refractive index modifiers, may be added to the adhesive composition P as desired.

Examples of UV absorbers include benzophenone-based, benzotriazole-based, benzoate-based, benzoxazole-based, triazine-based, phenylsalicylate-based, cyanoacrylate-based, and nickel cerium salt-based compounds. Among these, at least one of benzophenone-based, benzotriazole-based, and triazine-based compounds is preferably used.

Examples of the benzophenone compounds include 2,2-dihydroxy-4-methoxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid hydrate, and 2-hydroxy-4-n-octyloxybenzophenone. Among these, 2,2-dihydroxy-4-methoxybenzophenone is preferably used.

Examples of the benzotriazole compounds include 2-(2-hydroxy-5-tert-butylphenyl)-2H-benzotriazole, octyl-3-[3-tert-butyl-4-hydroxy-5-(5-chloro-2H-benzotriazol-2-yl)phenyl]propionate, 2-ethylhexyl-3-[3-tert-butyl-4-hydroxy-5-(5-chloro-2H-benzotriazol-2-yl)phenyl]propionate, and 3-(2H-benzotriazol-2-yl)-5-(1,1-dimethylethyl)-4-hydroxy-phenylpropionic acid.

Examples of the triazine compounds include 2,4-bis[2-hydroxy-4-butoxyphenyl]-6-(2,4-dibutoxyphenyl)-1,3,5-triazine and 2-[4,6-di(2,4-dimethylphenyl)-1,3,5-triazin-2-yl]-5-octyloxyphenol.

The above UV absorbers can be used alone or in combination of two or more.

When the adhesive composition P contains a UV absorber, the content of the UV absorber is preferably 0.1 parts by mass or greater, particularly 0.5 parts by mass or greater, and even more preferably 1.0 parts by mass or greater, per 100 parts by mass of the (meth)acrylate polymer (A). Furthermore, the content is preferably 15 parts by mass or less, more preferably 12 parts by mass or less, particularly 8 parts by mass or less, and even more preferably 4 parts by mass or less. By maintaining the UV absorber content within the above range, the adhesive layer readily exhibits excellent UV absorption properties.

Furthermore, the adhesive composition P refers to a mixture of various components remaining in the adhesive layer in its original or reacted state. The adhesive composition P does not include components removed during the drying step, such as the polymerization solvent or dilution solvent described below.

(2) Preparation of Adhesive Composition The adhesive composition P can be prepared by preparing a (meth)acrylate polymer (A), mixing the obtained (meth)acrylate polymer (A) with a rust preventer (B) and a long-chain alkylamine (C), and adding a silane compound (D), an alkanediol (E), a crosslinker (F), an active energy ray curable component (G), a photopolymerization initiator (H), an additive, etc. as desired.

The (meth)acrylate polymer (A) can be produced by polymerizing a mixture of monomer units constituting the polymer using a conventional free radical polymerization method. The polymerization of the (meth)acrylate polymer (A) can be carried out by a solution polymerization method, etc., using a polymerization initiator as desired. Examples of polymerization solvents include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, and methyl ethyl ketone, and two or more solvents may be used in combination.

Examples of polymerization initiators include azo compounds and organic peroxides, and two or more thereof may be used in combination. Examples of azo compounds include 2,2′-azobisisobutyronitrile, 2,2′-azobis(2-methylbutyronitrile), 1,1′-azobis(cyclohexane-1-carbonitrile), 2,2′-azobis(2,4-dimethylvaleronitrile), 2,2′-azobis(2,4-dimethyl-4-methoxyvaleronitrile), dimethyl-2,2′-azobis(2-methylpropionate), 4,4′-azobis(4-cyanovaleric acid), 2,2′-azobis(2-hydroxymethylpropionitrile), and 2,2′-azobis[2-(2-imidazolin-2-yl)propane].

Examples of the organic peroxide include benzoyl peroxide, t-butyl perbenzoate, isopropyl hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di(2-ethoxyethyl) peroxydicarbonate, t-butyl peroxyneodecanoate, t-butyl peroxytrimethylacetate, (3,5,5-trimethylhexanoyl) peroxide, dipropyl peroxide, and diacetyl peroxide.

Furthermore, in the above polymerization step, the weight average molecular weight of the obtained polymer can be adjusted by adding a chain transfer agent such as 2-hydroxyethanol.

After obtaining the (meth)acrylate polymer (A), a rust preventer (B) and a long-chain alkylamine (C) are added to the solution of the (meth)acrylate polymer (A). A silane compound (D), an alkanediol (E), a crosslinking agent (F), an active energy ray-curable component (G), a photopolymerization initiator (H), additives, a diluting solvent, and the like are added as desired. The mixture is thoroughly mixed to obtain a solvent-diluted adhesive composition P (coating solution).

Examples of the diluting solvent include aliphatic hydrocarbons such as hexane, heptane, and cyclohexane, aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as dichloromethane and dichloroethane, alcohols such as methanol, ethanol, propanol, butanol, and 1-methoxy-2-propanol, ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone, and cyclohexanone, esters such as ethyl acetate and butyl acetate, and cellosol-based solvents such as ethyl cellosolve.

The concentration and viscosity of the thus prepared coating solution are not particularly limited, as long as they are within a coatable range, and can be appropriately selected depending on the circumstances. For example, the adhesive composition P can be diluted to a concentration of 10-40% by weight. Furthermore, the addition of a diluting solvent or the like is not essential when obtaining the coating solution. As long as the adhesive composition P has a coatable viscosity, no diluting solvent is required. In this case, the adhesive composition P becomes a coating solution in which the polymerization solvent of the (meth)acrylate polymer (A) is directly used as the diluting solvent.

[Adhesive] The adhesive of this embodiment is formed by bridging the adhesive composition P described above. Bridging of the adhesive composition P is typically achieved by heating. Furthermore, this heating process can also serve as a drying process to evaporate the diluent, etc., from the coating layer of the adhesive composition P applied to the desired object.

During the heat treatment, the heating temperature is preferably between 50°C and 150°C, particularly between 70°C and 120°C. Furthermore, the heating time is preferably between 30 seconds and 10 minutes, particularly between 50 seconds and 2 minutes. After the heat treatment, a 1-2 week aging period at room temperature (e.g., 23°C, 50% RH) may be provided, if necessary. If this aging period is required, the adhesive is formed after the heat treatment. Otherwise, the adhesive is formed after the heat treatment.

Regarding the gel fraction of the adhesive of this embodiment, the lower limit is preferably 30% or more, particularly preferably 40% or more, and further preferably 45% or more. When the gel fraction of the adhesive is within the above lower limit, the cohesion becomes higher and the durability is higher. In addition, the upper limit of the gel fraction is preferably 90% or less, more preferably 80% or less, and particularly preferably 75% or less. From the perspective of further improving the adhesion, it is preferably 65% or less, and further preferably 55% or less. When the gel fraction of the adhesive is within the above upper limit, the adhesive does not over-harden, and the adhesion is higher. In addition, the rustproofing agent (B) and the long-chain alkylamine (C) become easily and well segregated on the surface of the adhesive layer. The method for determining the gel fraction of the adhesive is shown in the test examples below.

(Adhesive Sheet) As shown in Figure 1, the adhesive sheet 1 of this embodiment is composed of two release sheets 12a and 12b, and an adhesive layer 11 that is in contact with the release surfaces of the two release sheets 12a and 12b and sandwiched between the release sheets 12a and 12b. However, the release sheets 12a and 12b are not essential components of the adhesive sheet 1 and are removed during the peeling process using the adhesive sheet 1. The release surface of a release sheet in this specification refers to the surface of the release sheet that exhibits releasability, including both surfaces that have been subjected to a releasable treatment and surfaces that exhibit releasability even without a releasable treatment.

(1) Adhesive layer The adhesive layer 11 is composed of the above-mentioned adhesive. The lower limit of the thickness of the adhesive layer 11 (measured in accordance with JIS K7130) is preferably 5 μm or more, more preferably 10 μm or more, particularly preferably 25 μm or more, and further preferably 45 μm or more. By setting the lower limit of the thickness of the adhesive layer 11 to the above value, excellent adhesion can be fully exerted. In addition, the upper limit of the thickness of the adhesive layer 11 is preferably 300 μm or less, more preferably 200 μm or less, particularly preferably 100 μm or less, and further preferably 70 μm or less. By setting the upper limit of the thickness of the adhesive layer 11 to the above value, processability becomes good. Furthermore, the rustproofing agent (B) and the long-chain alkylamine (C) are easily and effectively segregated on the surface of the adhesive layer. Furthermore, the adhesive layer 11 can be formed as a single layer or by stacking multiple layers.

(2) Peeling sheet The peeling sheets 12a and 12b are not particularly limited, and known plastic films can be used. For example, polyethylene film, polyacrylic acid 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, copolymer resin film, ethylene-(meth)acrylic acid copolymer film, ethylene-(meth)acrylate copolymer film, polystyrene film, polycarbonate film, polyimide film, fluororesin film, etc. In addition, such bridging films can also be used. Furthermore, such laminated films can also be used.

The release surfaces of the release sheets 12a and 12b (particularly the surface in contact with the adhesive layer 11) are preferably subjected to a release treatment. Examples of release agents used for the release treatment include alkyd, silicone, fluorine, unsaturated polyester, polyolefin, and wax-based release agents. Furthermore, it is preferred that one of the release sheets 12a and 12b be a heavy-peel type with a strong release force, while the other be a light-peel type with a weak release force.

There is no particular limitation on the thickness of the peeling sheets 12a and 12b, but the thickness is generally about 20 to 150 μm.

(3) Production of Adhesive Sheet As an example of producing the adhesive sheet 1, a coating liquid of the adhesive composition P is applied to the release surface of one release sheet 12a (or 12b), and a heat treatment is performed to thermally bridge the adhesive composition P to form a coating layer. Then, the release surface of the other release sheet 12b (or 12a) is laminated with the coating layer. If a aging period is required, it is provided. If no aging period is required, the coating layer directly becomes the adhesive layer 11. In this way, the adhesive sheet 1 can be obtained. The conditions for the heat treatment and aging are as described above.

As another example of manufacturing the adhesive sheet 1, a coating liquid of the adhesive composition P is applied to the release surface of one release sheet 12a, and then heated to form bridges of the adhesive composition P to form a coating layer, thereby obtaining a release sheet 12a with a coating layer. Furthermore, a coating liquid of the adhesive composition P is applied to the release surface of the other release sheet 12b, and then heated to form bridges of the adhesive composition P to form a coating layer, thereby obtaining a release sheet 12b with a coating layer. Next, release sheet 12a with a coating layer and release sheet 12b with a coating layer are attached to each other with the coating layers in contact. A aging period is provided if necessary; otherwise, the coating layers directly become adhesive layer 11. This produces the adhesive sheet 1. This manufacturing example allows for stable production even when the adhesive layer 11 is relatively thick.

As a method for applying the coating liquid of the adhesive composition P, for example, a rod coating method, a doctor blade coating method, a roll coating method, a blade coating method, a die coating method, a gravure coating method, etc. can be used.

(4) Physical Properties of Adhesive Sheet (4-1) Adhesion Regarding the adhesion of the adhesive sheet 1 of this embodiment to sodium glass, the lower limit is preferably 10 N/25 mm or greater, particularly preferably 15 N/25 mm or greater, and further preferably 20 N/25 mm or greater. When the lower limit of the adhesion is within the above range, the durability of the adhesive layer 11 is further improved. Furthermore, the upper limit of the adhesion is preferably 100 N/25 mm or less, more preferably 80 N/25 mm or less, particularly preferably 60 N/25 mm or less, and further preferably 45 N/25 mm or less. When the upper limit of the adhesion is within the above range, good reworkability is achieved, and re-bonding is possible even in the event of a bonding error.

The adhesion strength described above is essentially measured using the 180° pull-peel method according to JIS Z0237:2009. However, the sample is 25mm wide and 100mm long. The sample is attached to the adherend and pressurized at 0.5MPa and 50°C for 20 minutes. The sample is then left at atmospheric pressure, 23°C, and 50% RH for 24 hours, and then measured at a peel speed of 300mm/min.

(4-2) Haze Value The haze value of the adhesive layer 11 of the adhesive sheet 1 of this embodiment is preferably 1% or less, more preferably 0.5% or less, particularly preferably 0.3% or less, and even more preferably 0.2% or less. By maintaining the haze value of the adhesive layer 11 within this range, light transmittance is excellent, making it suitable for use in displays. The lower limit of the haze value is not particularly limited, but is preferably 0% or greater, and more preferably 0.01% or greater.

Furthermore, the above haze value also includes the characteristic value of the thickness of the adhesive layer. Regardless of the thickness of the adhesive layer, it is best to meet the above haze value. Here, the haze value in this specification is the value measured in accordance with JIS K7136:2000.

(4-3) Total Light Transmittance The total light transmittance of the adhesive layer 11 of the adhesive sheet 1 of this embodiment is preferably 70% or greater, more preferably 80% or greater, particularly preferably 90% or greater, further preferably 95% or greater, and most preferably 99% or greater. By achieving such a total light transmittance of the adhesive layer 11, the adhesive sheet 1 exhibits excellent light transmittance and is suitable for use as a display. The upper limit of the total light transmittance is generally 100%. The total light transmittances described in this specification are values measured in accordance with JIS K7361-1:1997.

(4-4) CIE 1976 L*a*b* Color System Regarding the adhesive layer 11 of the adhesive sheet 1 of this embodiment, the absolute value of the chromaticity a* specified in the CIE 1976 L*a*b* color system is preferably 0 or greater, particularly 0.1 or greater. Furthermore, the absolute value of the chromaticity a* is preferably 0.8 or less, particularly 0.6 or less, and even more preferably 0.4 or less. The absolute value of the chromaticity b* of the adhesive layer 11 is preferably 0 or greater, particularly 0.1 or greater. Furthermore, the absolute value of the chromaticity b* is preferably 0.8 or less, particularly 0.6 or less, and even more preferably 0.4 or less. As described above, the adhesive layer 11 has a color tone suitable for use as a display. Furthermore, the measurement methods for lightness L*, chromaticity a*, and b* in this specification are as shown in the test examples described below.

[Display] The display of this embodiment comprises: a first display component; a second display component; and an adhesive layer for bonding the first and second display components to each other. The adhesive layer is composed of the adhesive described above in this embodiment. The first display component and/or the second display component has an electrode made of a metal or metal oxide on at least the bonding side (adhesive layer side). Preferably, the second display component has the aforementioned electrode on at least the bonding side.

Examples of the display include liquid crystal (LCD) displays, light emitting diode (LED) displays, organic electroluminescent (EL) displays, electronic paper, and the like, and may also be touch panels. Furthermore, the display may also be a component that constitutes these.

The first display component and the second display component can both be rigid and non-bending. The adhesive layer obtained from the adhesive composition P allows the rigid first display component and the rigid second display component to be bonded together without any problems.

The first display component is preferably a protective panel composed of a laminate containing a glass plate, a plastic plate, or the like. The first display component may also have a stepped surface on the adhesive layer side. Specifically, the stepped surface is preferably formed in accordance with the stepped surface of the printed layer. The printed layer is typically formed in a frame shape.

The glass plate is not particularly limited, and examples thereof include chemically strengthened glass, alkali-free glass, quartz glass, sodium calcium 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 typically 0.1 to 5 mm, preferably 0.2 to 2 mm.

The plastic plate is not particularly limited, and examples thereof include acrylic plates, polycarbonate plates, etc. The thickness of the plastic plate is not particularly limited, but is generally 0.2 to 5 mm, preferably 0.4 to 3 mm.

Furthermore, various functional layers (electrode layer, silicon dioxide layer, hard coating layer, anti-glare layer, etc.) can be provided on one or both sides of the above-mentioned glass plate or plastic plate, and optical components can also be laminated.

The material constituting the printed layer is not particularly limited; known materials for printing can be used. The lower limit of the thickness of the printed layer, i.e., the height of the step, is preferably 3 μm or greater, more preferably 5 μm or greater, particularly preferably 7 μm or greater, and most preferably 10 μm or greater. By setting the lower limit above this, sufficient concealment of the circuit wiring, etc., from the viewer's side, can be ensured. Furthermore, the upper limit is preferably 50 μm or less, more preferably 35 μm or less, particularly preferably 25 μm or less, and even more preferably 20 μm or less. By setting the upper limit below this, deterioration of the adhesive layer's ability to follow the step of the printed layer can be prevented.

The second display component is preferably an optical component to be attached to the first display component, a display module (for example, a liquid crystal (LCD) module, a light-emitting diode (LED) module, an organic electroluminescent (organic EL) module, etc.), an optical component that is part of the display module, or a laminate that includes a display module, and has an electrode made of metal or metal oxide on at least the surface on the adhesive layer side.

The above-mentioned optical components include thin film sensors, electrode films, metal nanowire films, wire grid polarizing films, etc.

Examples of electrodes made of the aforementioned metals include metal wiring (including grid, lattice, and nanowire forms) made of silver, silver alloys, copper, and copper alloys. Electrodes constituting touch panels are particularly well-suited examples, and specifically, metal wiring included in thin-film sensors is a good example. Among these metal wirings, metal wiring composed of nanoparticles of silver or silver alloys is preferred. Silver alloys, particularly those containing silver with palladium and copper added to silver, are particularly preferred. The adhesive layer 11 can provide excellent migration prevention for these metal wirings.

Electrodes made of the aforementioned metal oxides include, for example, those formed by patterning a transparent conductive film made of a metal oxide such as tin-doped indium oxide (ITO) or zinc oxide. Among these, patterning a transparent conductive film made of ITO is particularly preferred. The adhesive layer 11 can exhibit an excellent anti-migration effect on this ITO transparent conductive film.

The wiring width of the positive and negative electrodes of the electrodes formed from the aforementioned metals or metal oxides is preferably 100 μm or less, more preferably 60 μm or less, particularly preferably 45 μm or less, and even more preferably 35 μm or less. Furthermore, the wiring width is preferably 10 μm or greater, more preferably 15 μm or greater, particularly preferably 20 μm or greater, and even more preferably 25 μm or greater. Wiring widths within the above ranges contribute to electrode miniaturization and narrowing of pitches while leveraging the excellent anti-migration effect of the adhesive layer of this embodiment, thereby contributing to improved electrode connection reliability.

The wiring distance between the positive and negative electrodes of the electrodes composed of the aforementioned metals or metal oxides is preferably 100 μm or less, more preferably 60 μm or less, particularly preferably 45 μm or less, and even more preferably 35 μm or less. Furthermore, this wiring distance is preferably 10 μm or greater, more preferably 15 μm or greater, particularly preferably 20 μm or greater, and even more preferably 25 μm or greater. A wiring distance within this range contributes to the miniaturization and narrowing of electrode pitches while leveraging the excellent anti-migration effect of the adhesive layer of this embodiment, thereby contributing to improved electrode connection reliability.

FIG2 shows a capacitive-mode touch panel 2 as an example of a display according to this embodiment. The touch panel 2 comprises a display module 3; a first thin-film sensor 5a deposited thereon via an adhesive layer 4; a second thin-film sensor 5b deposited thereon via a first adhesive layer 11; and a cover material 6 deposited thereon via a second adhesive layer 11. A printed layer 7 is formed on the surface of the cover material 6 facing the second adhesive layer 11, resulting in a step difference between the presence and absence of the printed layer 7. In this embodiment, the cover member 6 corresponds to the first display component, the second thin film sensor 5b corresponds to the second display component, or the second thin film sensor 5b corresponds to the first display component, and the first thin film sensor 5a corresponds to the second display component.

Considering the effect of preventing migration, it is preferred that both the first adhesive layer 11 and the second adhesive layer 11 of the touch panel 2 be the adhesive layer 11 of the adhesive sheet 1. Furthermore, when the first adhesive layer 11 or the second adhesive layer 11 is not the adhesive layer 11 of the adhesive sheet 1, examples of adhesives constituting the adhesive layer include acrylic adhesives, rubber adhesives, silicone adhesives, urethane adhesives, polyester adhesives, and polyvinyl ether adhesives, with acrylic adhesives being preferred.

Adhesive layer 4 may be formed from adhesive layer 11 of adhesive sheet 1, or may be formed from another adhesive or adhesive sheet. In the latter case, examples of adhesives constituting adhesive layer 4 include acrylic adhesives, rubber adhesives, silicone adhesives, urethane adhesives, polyester adhesives, and polyvinyl ether adhesives, with acrylic adhesives being preferred.

In this embodiment, the first thin film sensor 5a and the second thin film sensor 5b each include a base film 51 and an electrode 52 formed on the base film 51. The base film 51 is not particularly limited, and for example, a polyethylene terephthalate film, an acrylic film, a polycarbonate film, or the like can be used.

The electrodes 52 described above can be exemplified. Typically, one of the electrodes 52 of the first thin-film sensor 5a and the second thin-film sensor 5b forms a circuit pattern in the X-axis direction, and the other forms a circuit pattern in the Y-axis direction.

In this embodiment, the electrode 52 of the second thin-film sensor 5b is located above the second thin-film sensor 5b in Figure 2 . Meanwhile, the electrode 52 of the first thin-film sensor 5a is located above the first thin-film sensor 5a in Figure 2 , but this is not limiting and the electrode 52 may also be located below the first thin-film sensor 5a .

The following describes an example method for manufacturing the touch panel 2. A first adhesive sheet 1 and a second adhesive sheet 1 are prepared as adhesive sheets 1. Release sheet 12a is peeled off from the first adhesive sheet 1, and the exposed adhesive layer 11 (first adhesive layer) is brought into contact with electrode 52 of first thin-film sensor 5a, thereby bonding the first thin-film sensor 5a. Separately, release sheet 12a is peeled off from the second adhesive sheet 1, and the exposed adhesive layer 11 (second adhesive layer 11) is brought into contact with electrode 52 of second thin-film sensor 5b, thereby bonding the second thin-film sensor 5b.

Next, the release sheet 12b on the other side of the first adhesive sheet 1 is peeled off, leaving the exposed first adhesive layer 11 in contact with the surface of the second thin-film sensor 5b opposite to the side on which the second adhesive layer 11 is deposited (the exposed surface of the base film 51 of the second thin-film sensor 5b), and the two are bonded together. This results in a laminated body in which the release sheet 12b, the second adhesive layer 11, the second thin-film sensor 5b, the first adhesive layer 11, and the first thin-film sensor 5a are deposited in this order.

Next, the adhesive layer 4 provided on the release sheet is bonded to the surface of the laminate facing the first thin film sensor 5a (the exposed surface of the base film 51 of the first thin film sensor 5a). Next, the release sheet 12b is peeled off from the laminate, and the exposed second adhesive layer 11 is bonded to the cover material 6 with the printed layer 7 side brought into contact with the second adhesive layer 11. This bonding process results in a structure in which the cover material 6, second adhesive layer 11, second thin film sensor 5b, first adhesive layer 11, first thin film sensor 5a, adhesive layer 4, and release sheet are stacked in this order.

Next, the release sheet is peeled off from the structure, and the exposed adhesive layer 4 is brought into contact with the display module 3, and the structure and the display module 3 are bonded together. In this way, the touch panel 2 shown in FIG. 2 is manufactured.

When the first adhesive layer 11 and/or the second adhesive layer 11 is formed of an active energy ray-curable adhesive, the adhesive layer 11 in the structure or touch panel 2 is irradiated with active energy rays. This polymerizes the active energy ray-curable component (G) in the adhesive layer 11, curing the adhesive layer 11 to form a cured adhesive layer. The energy rays irradiating the adhesive layer 11 are typically performed from one side of the structure or touch panel 2, preferably from the side of the cover material 6.

Furthermore, the so-called active energy rays refer to electromagnetic waves or charged particle rays that contain energy quanta. Specifically, ultraviolet rays and electron beams can be cited. Among active energy rays, ultraviolet rays are particularly preferred because they are easy to handle.

UV irradiation can be performed using high-pressure mercury lamps, Fusion H lamps, xenon lamps, etc. The UV irradiation dose is preferably between 50 and 1000 mW/ ^cm² , preferably between 100 and 600 mW/ ^cm² . Furthermore, the light intensity is preferably between 50 and 10,000 mJ/ ^cm² , more preferably between 80 and 5,000 mJ/ ^cm² , and particularly preferably between 200 and 2,000 mJ/ ^cm² . Electron beam irradiation can be performed using an electron beam accelerator, etc., with an optimal dose of 10 to 1,000 krad.

The gel fraction of the adhesive constituting the above-mentioned adhesive layer after hardening (adhesive after active energy ray irradiation) is preferably 35% or more as the lower limit, particularly preferably 50% or more, and further preferably 65% or more. When the lower limit of the gel fraction of the adhesive after active energy ray irradiation is above, the durability is higher. In addition, the above-mentioned gel fraction is preferably 90% or less as the upper limit, particularly preferably 80% or less, and further preferably 75% or less. When the upper limit of the gel fraction of the adhesive after active energy ray irradiation is above, it is possible to prevent the adhesive force of the adhesive layer after hardening from decreasing and deteriorating the durability. The method for measuring the gel fraction of the adhesive after active energy ray irradiation is shown in the test example described below.

The adhesive strength of the adhesive sheet having the cured adhesive layer to sodium glass preferably has a lower limit of 10 N/25 mm or less, more preferably 20 N/25 mm or more, particularly preferably 30 N/25 mm or more, and even more preferably 40 N/25 mm or more. When the lower limit of the adhesive strength is within the above range, the resulting product (touch panel 2) has high durability. The upper limit of the adhesive strength is not particularly limited, but is generally preferably 100 N/25 mm or less, particularly preferably 80 N/25 mm or less, and even more preferably 60 N/25 mm or less.

The adhesion strength described above is essentially measured using the 180° pull-peel method according to JIS Z0237:2009, except that the test sample is 25 mm wide and 100 mm long. This sample is attached to the adherend and pressurized at 0.5 MPa and 50°C for 20 minutes. It is then irradiated with active energy radiation (UV light) under the test conditions described below. The sample is then left at atmospheric pressure, 23°C, and 50% RH for 24 hours, and then measured at a peel speed of 300 mm/min.

The touch panel 2 is placed under high temperature and high humidity conditions. In this state, when a voltage is applied to the electrode 52, the migration of the electrode 52 is effectively suppressed, and the change in the resistance value of the electrode 52 is also effectively suppressed. This prevents the touch panel 2 from malfunctioning due to disconnection or short circuit of the electrode 52.

Here, the change in the resistance value of electrode 52 will be described in detail. When a sodium glass and an electrode plate (a silver wiring electrode plate in this embodiment) are bonded together via adhesive layer 11 of adhesive sheet 1 according to this embodiment and the resulting laminate is subjected to a durability test, the electrode plate's resistance change rate, as calculated using the following formula, is preferably less than 50%, particularly less than 30%, and even more preferably less than 15%. While the lower limit is not particularly limited, it is preferably 0% or greater. Similarly, when sodium glass and an ITO evaporated film are bonded via the adhesive layer 11 of the adhesive sheet 1 according to the embodiment and the resulting laminate is subjected to a durability test, the resistance change rate of the ITO evaporated film, as calculated using the following formula, is preferably less than 200%, particularly less than 150%, and even more preferably less than 100%. The lower limit is not particularly limited, but is preferably 0% or greater. Resistance change rate (%) = {(RR ⁰ )/R ⁰ } × 100 Where R ⁰ is the initial resistance value (Ω) before the durability test, and R is the resistance value (Ω) after the durability test. Details of the resistance change rate measurement method are shown in the test examples below.

The embodiments described above are provided to facilitate understanding of the present invention and are not intended to limit the present invention. Therefore, the elements disclosed in the embodiments described above include all design modifications and equivalents within the technical scope of the present invention.

For example, either the release sheet 12a or the release sheet 12b of the adhesive sheet 1 may be omitted. Furthermore, the cover material 6 and the printed layer 7 may not be formed on the touch panel 2. [Embodiment]

Hereinafter, the present invention will be described in more detail with reference to embodiments, etc. However, the scope of the present invention is not limited to these embodiments, etc.

(Example 1) 1. Preparation of (Meth)acrylate Polymer (A) (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 via solution polymerization. The molecular weight of the (meth)acrylate Polymer (A), measured by the method described below, revealed a weight-average molecular weight (Mw) of 700,000.

2. Preparation of the Adhesive Composition 100 parts by mass (solids conversion value; the same applies hereinafter) of the (meth)acrylate polymer (A) obtained in step 1 above, 0.15 parts by mass of 1H-benzotriazole (B1) as a rust preventer (B), 0.15 parts by mass of a polyoxyethylene alkylamine represented by the following general formula (c) (weight average molecular weight: 900, carbon number of R: 14-18, sum of m and n: 15) as a long-chain alkylamine (C), 0.25 parts by mass of an organosilicon compound (D1) represented by the following structural formula (II) as a silane compound (D), 1.0 parts by mass of dipropylene glycol monomethyl ether as an alkanediol (E), and 0.6 parts by mass of trihydroxymethylpropane-modified tris(tolylene) diisocyanate (TOYO) as a crosslinker (F) were added. Mix with CHEM (product name "BHS8515"), stir thoroughly, and dilute with methyl ethyl ketone to obtain a coating solution of the adhesive composition: [Chemical 3] [Chemistry 4] .

Here, the formulations (solid content conversion) of the adhesive compositions, based on 100 parts by mass (solid content conversion) of the (meth)acrylate polymer (A), are shown in Table 1. The details of the numbers and components listed in Table 1 are as follows. [(Meth)acrylate polymer (A)] 2EHA: 2-ethylhexyl acrylate MMA: methyl methacrylate HEA: 2-hydroxyethyl acrylate IBXA: isoborneol acrylate ACMO: N-acryloylmorpholine BA: n-butyl acrylate [Rust-proofing agent (B)] B1: 1H-benzotriazole B2: 1-[N,N-bis(2-ethylhexyl)aminomethyl]methylbenzotriazole [Silane compound (D)] D1: The organosilicon compound represented by the above structural formula (II) D2: The organosilicon compound represented by the following structural formula (III) [Chemical 5] [Active energy ray curing component (G)] ε-caprolactone-modified tris(2-acryloyloxyethyl) isocyanurate [Photopolymerization initiator (H)] 1:1 (mass ratio) mixture of 1-hydroxycyclohexyl-phenyl-ketone and benzophenone [Ultraviolet absorber] 2,2-dihydroxy-4-methoxybenzophenone

3. Preparation of Adhesive Sheet The coating solution of the adhesive composition obtained in step 2 above was applied using a doctor blade coater to the release-treated surface of a heavy-peel release sheet (LINTEC, product name "SP-PET382150," thickness: 38 μm) on one side of a polyethylene terephthalate film that had been treated with a silicone release agent. The sheet was then heat-treated at 80°C for 1 minute and then at 110°C for 1 minute to form a coating layer (thickness: 50 μm).

Next, the coating layer on the heavy-peel release sheet obtained above was bonded to a light-peel release sheet (LINTEC, product name "SP-PET381130"), one side of which was treated with a silicone release agent. The release-treated surface of the light-peel release sheet was in contact with the coating layer. The sheets were then aged at 23°C and 50% RH for 7 days to produce an adhesive sheet consisting of a heavy-peel release sheet/adhesive layer (thickness: 50 μm)/light-peel release sheet.

(Examples 2-11, Comparative Examples 1-7) Adhesive sheets were produced in the same manner as in Example 1, except that the types and ratios of the monomers constituting the (meth)acrylate polymer (A), the weight-average molecular weight of the (meth)acrylate polymer (A), the type and amount of the rust inhibitor (B), the amount of the long-chain alkylamine (C), the type and amount of the silane compound (D), the amount of the alkanediol (E), and the crosslinking agent (F) were changed to those shown in Table 1. Furthermore, in Example 2, a UV absorber was added, and in Examples 6, 7, 9, 10 and Comparative Examples 6 and 7, an active energy ray-curable component (G) and a photopolymerization initiator (H) were added.

The weight-average molecular weight (Mw) mentioned above is the polystyrene-equivalent weight-average molecular weight measured using gel permeation chromatography (GPC) under the following conditions (GPC measurement). <Measurement Conditions> GPC measurement apparatus: HLC-8020 manufactured by TOSOH Corporation GPC columns (used in the following order): TSK guard column HXL-H manufactured by TOSOH Corporation TSK ge1 GMHXL (×2) TSK ge1 G2000HXL Measurement solvent: Tetrahydrofuran Measurement temperature: 40°C

[Test Example 1] (Gel Fraction Determination) The adhesive sheets obtained in the Examples, Comparative Examples, and Reference Examples were cut into 80 mm x 80 mm sheets. The adhesive layer was placed on a polyester mesh (mesh size 200). The mass of the adhesive layer was measured using a precision balance. The mass of the mesh alone was subtracted to calculate the mass of the adhesive alone. This mass was designated M1.

Next, the adhesive on the polyester mesh was immersed in ethyl acetate at room temperature (23°C) for 24 hours. Afterwards, the adhesive was removed and air-dried for 24 hours at a temperature of 23°C and a relative humidity of 50%, and further dried in an oven at 80°C for 12 hours. After drying, its mass was weighed on a precision balance, and the mass of the mesh alone was deducted to calculate the mass of the adhesive alone. The mass at this time is M2. The gel fraction (%) is expressed as (M2/M1)×100. In this way, the gel fraction of the adhesive (before UV irradiation) was derived. The results are shown in Table 2.

Furthermore, regarding the adhesive sheets of Examples 6, 7, 9, and 10 and Comparative Examples 6 and 7, the gel fraction was measured before and after the adhesive layer was irradiated with ultraviolet light (UV) (irradiated from the heavy-peel release sheet side). The UV irradiation conditions are as follows.

UV irradiation conditions: A high-pressure mercury lamp was used. Illuminance: 200 mW/ ^cm² , light intensity: 1000 mJ/ ^cm² . UV irradiance: The light meter used was the UVPF-A1 manufactured by EYE GRAPHICS.

[Test Example 2] (Haze Value Measurement) The adhesive layer of the adhesive sheets produced in the Examples and Comparative Examples was attached to glass to serve as the test sample. After background measurement using the glass, the haze value (total light haze value; %) of the test sample was measured using a haze meter (manufactured by Nippon Denshoku Industries, product name "NDH-5000") in accordance with JIS K7136:2000. The results are shown in Table 2.

[Test Example 3] (Measurement of Total Light Transmittance) The adhesive layer of the adhesive sheets produced in the Examples and Comparative Examples was attached to glass to serve as the test sample. After background measurement using the glass, the total light transmittance (%) of the test sample was measured using a haze meter (manufactured by Nippon Denshoku Industries, product name "SH-7000") in accordance with JIS K7361-1:1997. The results are shown in Table 2.

[Test Example 4] (Measurement of the L*a*b* Color System) The adhesive layers of the adhesive sheets produced in the Examples and Comparative Examples were measured for chromaticity a* and chromaticity b* as specified in the CIE 1976 L*a*b* color system using a simultaneous spectrophotometric colorimeter (manufactured by Nippon Denshoku Industries, Ltd., product name "SQ2000"). The results are shown in Table 2.

[Test Example 5] (Adhesion Measurement) The light-peel release sheet obtained in the Examples and Comparative Examples was peeled off, and the exposed adhesive layer was attached to the adhesive layer of a polyethylene terephthalate (PET) film (manufactured by Toyobo Co., Ltd., product name "PET A4300," thickness: 100 μm) with a high-adhesion layer. This produced a release sheet/adhesive layer/PET film laminate. The resulting laminate was cut into pieces 25 mm wide and 100 mm long to prepare a sample.

At 23°C and 50% RH, a heavy-peel release sheet was peeled from the sample. The exposed adhesive layer was attached to a sodium glass sheet (manufactured by Nippon Sheet Glass Co., Ltd.). The sheet was then pressurized at 0.5 MPa and 50°C for 20 minutes in a Kurihara Seisakusho autoclave. After 24 hours at 23°C and 50% RH, the adhesive strength (N/25mm) was measured using a tensile tester (Orientec, product name "Tensilon") at a peel speed of 300 mm/min and a peel angle of 180 degrees. Conditions other than those specified here were measured in accordance with JIS Z0237:2009. The results are shown in Table 2.

Separately, the adhesive strength of the adhesive sheets from Examples 6, 7, 9, and 10, and Comparative Examples 6 and 7, after ultraviolet (UV) irradiation was measured. Specifically, after the autoclave treatment, UV light was irradiated from the sodium glass side of the adhesive layer under the same conditions as in Test Example 1. Afterwards, the sheets were left at 23°C and 50% RH for 24 hours, and the adhesive strength (N/25mm; after UV) was measured in the same manner as above. The results are shown in Table 2.

[Test Example 6] (Evaluation of the Migration Prevention Effect) (1) Preparation of Silver Wiring Electrode Plate On the adhesion-treated surface of a polyethylene terephthalate (PET) film (manufactured by TORAY, product name "Lumirror U48", thickness: 125μm), silver paste (manufactured by TOYO CHEM, product name "RA FS088") was applied in straight lines and parallel to the positive electrode wiring and the negative electrode wiring by screen printing. The silver paste was then cured by heating at 135°C for 30 minutes to obtain an electrode plate with silver wiring (silver wiring electrode plate). The positive and negative wiring widths are 30μm each, and the wiring spacing is 30μm.

(2) Evaluation of the migration prevention effect The light-peel release sheet obtained from the adhesive sheet of the embodiment and the comparative example was peeled off, and the exposed adhesive layer was adhered to the easy-adhesive layer of a polyethylene terephthalate (PET) film (manufactured by Toyobo Co., Ltd., product name "PET A4300", thickness: 100 μm) having an easy-adhesive layer to obtain a heavy-peel release sheet/adhesive layer/PET film laminate. Next, the heavy-peel release sheet was peeled off from the above laminate, and the exposed adhesive layer was adhered to the positive electrode wiring and the negative electrode wiring of the above electrode. The samples were then autoclaved at 50°C and 0.5 MPa for 20 minutes and then placed at 23°C and 50% RH for 24 hours.

Furthermore, regarding the adhesive sheets of Examples 6, 7, 9, 10 and Comparative Examples 6 and 7, after the above-mentioned autoclave treatment, ultraviolet rays were irradiated from the PET film side toward the adhesive layer under the same conditions as in Test Example 1, and these were used as samples.

The samples were left standing under humid conditions of 105°C and 100% RH. A 5V voltage was applied between the electrodes to conduct a migration test. Twenty hours after the start of the test, the positive and negative electrode wirings were observed under an optical microscope (magnification: 10x), and the migration prevention effect was evaluated according to the following evaluation criteria. The results are shown in Table 2. Furthermore, no abnormalities such as lifting, peeling, or bubbles were observed in any of the samples from the Examples and Comparative Examples. ◎: No dissolution of the positive electrode wiring or formation of dendritic crystals in the negative electrode wiring was observed. ○: No dissolution of the positive electrode wiring or dendritic crystal formation was observed on the negative electrode wiring, but discoloration of the wiring was observed. ╳: Dissolution of the positive electrode wiring and dendritic crystal formation were observed on the negative electrode wiring.

[Test Example 7] (Evaluation of Resistance Change) The sample produced in Test Example 6 was used as Measurement A (silver wiring electrode plate sample).

Furthermore, a sodium glass sheet (70 mm long × 150 mm wide × 1.0 mm thick; manufactured by Nippon Sheet Glass Co., Ltd.) and an ITO-evaporated film (TETOLIGHT TCF KH150NMH2-125-U6/T2, manufactured by Oike Industries, Ltd.) were bonded together via the adhesive layer of the adhesive sheets obtained in Examples and Comparative Examples, with the ITO-evaporated film side in contact with the adhesive layer. The sheet was then autoclaved at 50°C and 0.5 MPa for 20 minutes and then left at 23°C and 50% RH for 24 hours to obtain Measurement Sample B (ITO-evaporated film sample).

Furthermore, regarding the adhesive sheets of Examples 6, 7, 9, 10 and Comparative Examples 6 and 7, after the above-mentioned autoclave treatment, ultraviolet rays were irradiated from the sodium glass side toward the adhesive layer under the same conditions as in Test Example 1, and these were used as measurement samples.

For the above-mentioned measurement sample A, the initial resistance value R ⁰ (Ω) was measured by applying a voltage of 5 V between the positive and negative electrode wiring. Meanwhile, for the above-mentioned measurement sample B, the initial resistance value R ⁰ (Ω) was measured using a non-contact resistance meter (manufactured by Napuson, product name "EC-80").

Next, place the test samples A and B in a 105°C, 100% RH, humid and hot environment for 3 hours. Afterwards, place them in a normal temperature and humidity environment at 23°C, 50% RH for 24 hours, and measure the resistance (Ω) in the same manner as the initial resistance value. This is the resistance value R after the endurance test. From the measured values, calculate the resistance change rate (%) using the following formula: Resistance change rate (%) = {(RR ⁰ )/R ⁰ } × 100

Based on the calculated resistance variation, the resistance variation was evaluated according to the following criteria. The results are shown in Table 2. <Evaluation Criteria for Silver Wiring Electrode Plate Samples> ◎: Resistance variation less than 15% ○: Resistance variation 15% or more but less than 30% △: Resistance variation 30% or more but less than 50% ╳: Resistance variation 50% or more <Evaluation Criteria for ITO Evaporated Film Samples> ◎: Resistance variation less than 100% ○: Resistance variation 100% or more but less than 150% △: Resistance variation 150% or more but less than 200% ╳: Resistance variation 200% or more

[Table 1] UV absorbers Mass - 2 - - - - - - - - - - - - - - - - Photopolymerization initiator (H) Mass - - - - - 0.5 0.5 - 0.5 0.5 - - - - - - 0.5 0.5 Active energy ray curing ingredient (G) Mass - - - - - 5 5 - 5 5 - - - - - - 5 5 Bridging agent (F) Mass 0.6 0.6 0.6 0.6 0.6 0.45 0.45 0.45 0.45 0.45 0.45 0.23 0.23 0.35 0.23 0.23 0.15 0.15 Alkanediol (E) Mass 1 1 1 1 - 1 1 1 1 1 1 - - - - 1 - - Silane compound (D) Mass 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 - 0.25 0.25 0.25 0.25 - - Kind D1 D1 D2 D1 D1 D1 D1 D1 D1 D1 D1 - D1 D1 D1 D1 - - Long-chain alkylamine (C) Mass 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 - - - 0.15 - - - Rust Repellent (B) Mass 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 - - 0.15 - - - - Kind B1 B1 B1 B2 B1 B1 B2 B1 B1 B2 B1 - - B1 - - - - Acrylate polymer (A) Mw 700,000 500,000 500,000 700,000 500,000 500,000 Composition 2EHA/MMA/HEA =60/20/20 2EHA/IBXA/ACMO/HEA =65/10/10/15 2EHA/BA/IBXA/ACMO/HEA =45/20/10/5/20 2EHA/MMA/HEA =60/20/20 2EHA/IBXA/ACMO/HEA =65/10/10/15 2EHA/BA/IBXA/ACMO/HEA =45/20/10/5/20 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Example 10 Example 11 Comparative example 1 Comparative example 2 Comparative example 3 Comparative example 4 Comparative example 5 Comparative example 6 Comparative example 7

[Table 2] Evaluation of resistance value changes ITO evaporated film ◎ ◎ ○ ◎ ○ ○ ○ ○ ○ ○ ○ △ ○ ○ △ ○ ╳ ╳ Silver wiring electrode plate ◎ ◎ ○ ◎ ○ ○ ○ ◎ ○ ○ ○ ╳ ╳ △ △ ╳ ╳ ╳ Evaluation of migration prevention effectiveness Silver wiring electrode plate ◎ ◎ ○ ◎ ○ ◎ ◎ ◎ ○ ○ ○ ╳ ╳ ╳ ╳ ╳ ╳ ╳ Adhesion force (N/25mm) After UV - - - - - 51 50 - 49 49 - - - - - - 50 48 Before UV 26 25 twenty three 26 26 38 39 40 38 38 41 twenty two 26 19 20 20 37 40 b* 0.2 0.7 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 a* -0.3 -0.6 -0.2 -0.2 -0.3 -0.3 -0.3 -0.3 -0.2 -0.3 -0.2 -0.2 -0.2 -0.3 -0.3 -0.3 -0.3 -0.3 Total light transmittance (%) ≧99 ≧99 ≧99 ≧99 ≧99 ≧99 ≧99 ≧99 ≧99 ≧99 ≧99 ≧99 ≧99 ≧99 ≧99 ≧99 ≧99 ≧99 Haze(%) 0.2 0.2 0.2 0.2 0.3 0.3 0.2 0.2 0.2 0.3 0.3 0.2 0.2 0.2 0.2 0.3 0.2 0.3 Gel fraction (%) After UV - - - - - 70 71 - 71 71 - - - - - - 72 70 Before UV 73 72 76 73 74 50 51 52 50 52 52 70 73 72 70 71 51 51 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Example 10 Example 11 Comparative example 1 Comparative example 2 Comparative example 3 Comparative example 4 Comparative example 5 Comparative example 6 Comparative example 7

As shown in Table 2, the adhesive sheet obtained in this example can prevent migration of the silver wiring electrode plate. Furthermore, the adhesive sheet obtained in this example can suppress changes in the resistance value of the silver wiring electrode plate and the ITO vapor-deposited film. [Industrial Profitability]

The adhesive composition, adhesive, and adhesive sheet of the present invention can be preferably used in, for example, a capacitive mode touch panel. Furthermore, the display of the present invention can be preferably used as, for example, a capacitive mode touch panel.

1: Adhesive sheet 11: Adhesive layer 12a, 12b: Peeling sheet 2: Touch panel 3: Display module 4: Adhesive layer 5a: First thin-film sensor 5b: Second thin-film sensor 51: Base film 52: Electrode 6: Covering material 7: Printing layer

[Figure 1] is a cross-sectional view of an adhesive sheet according to one embodiment of the present invention. [Figure 2] is a cross-sectional view showing an example configuration of a display (touch panel).

1: Adhesive sheet

11: Adhesive layer

12a, 12b: Peeling film

Claims (11)

An adhesive composition comprising: a (meth)acrylate polymer (A); a benzotriazole-based compound as a rust repellent (B); a long-chain alkylamine (C) containing an amine having a long-chain alkyl group with 10 or more and 24 carbon atoms in its molecule; a silane compound (D) having alkoxysilyl groups at both ends; and a bridging agent (F). The adhesive composition of claim 1, wherein the adhesive composition contains an alkanediol (E). The adhesive composition of claim 1, wherein the long-chain alkylamine (C) is a tertiary amine. The adhesive composition of claim 1, wherein the (meth)acrylate polymer (A) does not contain a carboxyl group-containing monomer as a monomer unit constituting the polymer. The adhesive composition of claim 1, wherein the (meth)acrylate polymer (A) comprises, as monomer units constituting the polymer, 6% by mass or more and 35% by mass or less of a hydroxyl group-containing monomer. The adhesive composition of claim 1, further comprising a UV absorber. The adhesive composition of claim 1 is an adhesive composition for forming an adhesive for contacting an electrode composed of metal or metal oxide. An adhesive is formed by bridging the adhesive composition of any one of claims 1 to 8. An adhesive sheet is characterized by comprising: two peeling sheets; and an adhesive layer sandwiched between the peeling sheets in a manner that the adhesive layer is in contact with the peeling surfaces of the two peeling sheets, wherein the adhesive layer is composed of the adhesive of claim 8. A display comprising: a first display component; a second display component; and an adhesive layer for bonding the first display component and the second display component to each other; the first display component and/or the second display component having an electrode composed of a metal or metal oxide on at least the surface of the bonding side; the adhesive layer is composed of the adhesive of claim 8. An adhesive composition for preventing or inhibiting migration, comprising: a (meth)acrylate polymer (A); a benzotriazole compound as a rust preventer (B); a long-chain alkylamine (C) containing an amine having a long-chain alkyl group with 10 or more and 24 carbon atoms in its molecule; and a bridging agent (F).