TWI746441B - Adhesive composition, adhesive, adhesive sheet and display body - Google Patents

Abstract

The present invention is an adhesive composition for forming an adhesive for bonding a first display body constituent member and a second display body constituent member having a level difference at least on the surface of the bonding side, wherein the first display body constituent member and/ Or the second display body constituent member has an electrode at least on the surface on the bonding side, and the adhesive composition is an adhesive composition containing a (meth)acrylate polymer (A) and a mercapto group-containing silane coupling agent (B) . The adhesive obtained from the adhesive composition can effectively prevent/inhibit the migration in the above-mentioned electrode.

Description

Adhesive composition, adhesive, adhesive sheet and display body

The present invention relates to an adhesive composition, adhesive and adhesive sheet that can be used in displays such as touch panels, and those using these displays.

In recent years, touch panels have been used as displays in various mobile electronic devices such as smart phones and tablet computers. As the touch panel method, there are a resistive film method, an electrostatic capacitance method, etc., and the electrostatic capacitance method is mainly used in the above-mentioned mobile electronic devices.

Recently, the size of touch panels has been increased, and as electrode materials for such touch panels, mesh-shaped metal electrodes, such as copper electrodes or silver electrodes, are being studied. However, when a conventional adhesive is used in contact with a metal electrode, especially a copper electrode or a silver electrode, ion migration (=Electrochemical migration; hereinafter referred to as "migration") may occur. Specifically, the electrode dissolves in the positive electrode to cause disconnection, or the precipitation of the positive electrode component forms a dendritic crystal in the negative electrode to cause a short circuit.

This migration is particularly likely to occur when a voltage is applied to the electrode under high temperature and high humidity. If this kind of migration occurs, the touch panel cannot be driven normally. Particularly recently, the miniaturization and narrowing of the electrode pitch is progressing, and the disconnection and short circuit of the electrode caused by migration are prone to occur.

However, Patent Document 1 has disclosed that the compound containing benzotriazole As a rust inhibitor, an adhesive composition for touch panels.

【Prior Technical Literature】

【Patent Literature】

Patent Document 1: JP 2014-177611 A

However, even if the benzotriazole compound, which is a rust inhibitor, has the anticorrosive effect of metal wiring, it cannot sufficiently prevent and suppress migration.

The present invention was completed in view of the above-mentioned actual situation, and its purpose is to provide an adhesive composition, adhesive, adhesive sheet, and display that can effectively prevent and inhibit migration.

In order to achieve the above-mentioned objects, firstly, the present invention provides an adhesive composition formed for bonding a first display body constituent member and a second display body constituent member having a step at least on the surface to be bonded. The adhesive is characterized in that the first display body constituent member and/or the second display body constituent member has an electrode at least on the surface to be bonded, and the adhesive composition contains a (meth)acrylate polymer ( A) Silane coupling agent with mercapto group (B) (Invention 1).

According to the adhesive obtained from the adhesive composition of the above-mentioned invention (Invention 1), especially by the action of the silane coupling agent (B) having a mercapto group, the adhesive can effectively prevent and inhibit the adhesion of the adhesive on the first display body in contact with it. Migration in the electrode of the constituent member and/or the constituent member of the second display body.

In the aforementioned invention (Invention 1), the aforementioned silane coupling with a mercapto group The agent (B) is preferably an oligomer type silane coupling agent containing a mercapto group (Invention 2).

In the above inventions (Inventions 1 and 2), it is preferable that the mercapto group equivalent of the organosilicon compound constituting the mercapto group-containing silane coupling agent (B) is 100 g/mole or more and 1000 g/mole or less (invention 3).

In the above inventions (Inventions 1 to 3), the content of the mercapto group-containing silane coupling agent (B) in the adhesive composition is 0.01 mass parts relative to 100 parts by mass of the (meth)acrylate polymer (A) Part or more and 5 parts by mass or less are preferable (Invention 4).

In the above inventions (Inventions 1 to 4), the (meth)acrylate polymer (A) preferably contains 3% by mass or more and 35% by mass or less of a hydroxyl-containing monomer as the monomer unit constituting the polymer (Invention 5).

In the above inventions (Inventions 1 to 5), it is preferable that the adhesive composition further contains a crosslinking agent (C) (Invention 6).

Second, the present invention provides an adhesive characterized in that the adhesive composition (Inventions 1 to 6) is cross-linked (Invention 7).

Third, the present invention provides an adhesive sheet having an adhesive layer (invention 8) composed of the aforementioned adhesive (invention 7).

In the above invention (Invention 8), the adhesive sheet includes two release sheets, and the adhesive layer is preferably sandwiched by the release sheets so as to be in contact with the release surfaces of the two release sheets (Invention 9).

Fourth, the present invention provides a display body comprising: a first display body constituent member having a step at least on the surface to be attached; a second display body constituent member; and a combination of the aforementioned first display body constituent member and the aforementioned second 2. Adhesive layer in which the constituent members of the display body are attached to each other. The characteristic of the display body is the aforementioned first display The body constituent member and/or the second display body constituent member has an electrode at least on the surface to be bonded, and the adhesive layer is the adhesive layer (Invention 10) of the adhesive sheet (Inventions 8, 9).

According to the adhesive composition, adhesive, adhesive sheet and display body of the present invention, migration can be effectively prevented and inhibited.

1‧‧‧Adhesive sheet

11‧‧‧Adhesive layer

12a、12b‧‧‧Release sheet

2‧‧‧Touch Panel

3‧‧‧Display module

4‧‧‧Adhesive layer

5a‧‧‧The first thin film sensor

5b‧‧‧The second thin film sensor

51‧‧‧Substrate film

52‧‧‧Electrode

6‧‧‧Cover material

7‧‧‧Printing layer

Figure 1 is a cross-sectional view of an adhesive sheet according to an embodiment of the present invention.

Fig. 2 is a cross-sectional view showing a configuration example of the touch panel.

Figure 3 is a reference image of the evaluation criteria in the evaluation of the migration prevention effect of Test Example 3.

Hereinafter, an embodiment of the present invention will be described.

〔Adhesive composition〕

The adhesive composition of this embodiment (hereinafter, sometimes referred to as "adhesive composition P".) is formed for bonding the first display body constituent member and the second display with a step at least on the bonding side surface The adhesive composition of the adhesive of the body constituent member (the first display body constituent member and/or the second display body constituent member has an electrode at least on the surface of the bonding side), which contains a (meth)acrylate polymer (A ) And the silane coupling agent (B) having a mercapto group, preferably further containing a crosslinking agent (C). In this specification, (meth)acrylate means both acrylate and methacrylate. Other similar terms are also the same. In addition, "polymer" is considered to include the concept of "copolymer". In addition, regarding the display body and the display body constituent members This will be described later.

Since the adhesive composition P of this embodiment contains the silane coupling agent (B) having a mercapto group, when the adhesive obtained from the adhesive composition P comes into contact with the electrode, it can prevent and inhibit the dissolution of the electrode in the positive electrode, and in the negative electrode Can prevent and inhibit the formation of dendrites. That is, the migration in the electrode can be effectively prevented and suppressed (this effect is sometimes referred to as the "migration prevention effect"). Thereby, even when the adhesive is in contact with, for example, an electrode that has been miniaturized and narrowed in pitch, it is possible to prevent disconnection and short-circuit of the electrode. In particular, when the above-mentioned electrodes are the electrodes of the touch panel, it is possible to prevent the drive failure of the touch panel caused by the disconnection and short-circuit of the electrodes.

Among them, as the above-mentioned electrodes, for example, metal electrodes (including mesh-shaped and grid-shaped ones) composed of copper, silver, etc., and transparent conductive films (including patterned ones) composed of tin-doped indium oxide (ITO), etc. Wait. Among the above-mentioned electrodes, a metal electrode mainly composed of an unoxidized metal, specifically, a metal electrode composed of copper or silver is preferable. Compared with metal oxides such as ITO, unoxidized metals have a higher ionization tendency. However, the adhesive obtained from the adhesive composition P of this embodiment can effectively prevent the electrode from breaking even in this case. Line and short circuit.

In addition, the adhesive layer composed of the adhesive obtained from the adhesive composition P containing the silane coupling agent (B) having the mercapto group is derived from the adhesive having the mercapto group at the interface with the display body constituting the adherend. The components of the silane coupling agent (B) have high adhesion to the constituent members of the display body and excellent step-following properties. Specifically, even when the adhesive layer is attached to a structural member of a display body with a step, and exposed to a predetermined time under high temperature and high humidity conditions (for example, at 85° C., 85% RH, 72 hours) , Can also suppress The system generates bubbles, floats, peeling, etc. near the level difference (excellent level difference followability under high temperature and high humidity conditions). Thereby, the reflection loss of the light generated in the vicinity of the level difference is suppressed, and the image quality of the display body can be maintained well.

(1) (Meth) acrylate polymer (A)

The (meth)acrylate polymer (A) uses alkyl (meth)acrylate having an alkyl group with a carbon number of 1 to 20 as the monomer unit constituting the polymer, which can exhibit better adhesiveness . From this point of view, the (meth)acrylate polymer (A) contains an alkyl group with a lower limit of 50% by mass or more, and an alkyl (meth)acrylate having 1 to 20 carbon atoms as a constituent of the polymer The monomer unit of the substance is preferably, more preferably 60% by mass or more, and more preferably 70% by mass or more. If the alkyl (meth)acrylate is contained in an amount of 50% by mass or more, the (meth)acrylate polymer (A) can exhibit better adhesiveness. In addition, the (meth)acrylate polymer (A) preferably contains the above-mentioned alkyl (meth)acrylate with an upper limit value of 97% by mass or less as the monomer unit constituting the polymer, and contains 90% by mass The following is particularly preferable, and it is more preferable to contain 85% by mass or less. By containing 97% by mass or less of the aforementioned alkyl (meth)acrylate, a preferable amount of other monomer components can be introduced into the (meth)acrylate polymer (A).

Examples of alkyl (meth)acrylates having 1 to 20 carbon atoms in the alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, (meth)acrylate, and (meth)acrylate. Base) n-butyl acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, (meth)acrylic acid N-decyl ester, n-dodecyl (meth)acrylate, tetradecyl (meth)acrylate, (meth) Cetyl acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, adamantyl (meth)acrylate, etc., from From the viewpoint of further improving the adhesiveness, a (meth)acrylate having an alkyl group-containing carbon number of 4 to 8 is preferred. These can be used alone or in combination of two or more kinds. In addition, the alkyl group in the alkyl (meth)acrylate having 1 to 20 carbon atoms in the alkyl group refers to a linear, branched, or cyclic alkyl group.

In addition, as an alkyl (meth)acrylate with a carbon number of 1-20, the homopolymer is used in combination with a hard monomer whose glass transition temperature (Tg) exceeds 0°C (70°C or higher is preferred). The soft monomer whose glass transition temperature (Tg) as a homopolymer is 0°C or less is also preferable. This is because the soft monomer maintains the adhesiveness and flexibility, and the hard monomer improves the cohesive force, so that it can be made into a display panel (touch panel) with better step-following properties.

The mass ratio of the above-mentioned hard monomer to soft monomer is preferably 5:95-40:60, especially 20:80-30:70.

Examples of the above-mentioned hard monomers include methyl acrylate (Tg10°C), methyl methacrylate (Tg105°C), isobornyl acrylate (Tg94°C), isobornyl methacrylate (Tg180°C), diamond acrylate Alkyl ester (Tg115°C), adamantyl methacrylate (Tg141°C), etc. These can be used alone or in combination of two or more kinds.

Among the above-mentioned hard monomers, from the viewpoint of preventing the bad influence on other properties such as adhesiveness and transparency and further exerting the performance of hard monomers, methyl acrylate, methyl methacrylate and isobornyl acrylate are preferred . If adhesion is also considered, methyl acrylate and methyl methacrylate are more preferred, and methyl methacrylate is particularly preferred.

As the above-mentioned soft monomer, an alkyl acrylate having a linear or branched alkyl group having a carbon number of 2 to 12 is preferably used. For example, preferably, 2-ethylhexyl acrylate (Tg-70°C), n-butyl acrylate (Tg-54°C) and the like can be cited. These can be used alone or in combination of two or more kinds.

The (meth)acrylate polymer (A) preferably contains a reactive functional group-containing monomer as a monomer unit constituting the polymer. The reactive functional group derived from the reactive functional group-containing monomer reacts with the crosslinking agent (C) described later to form a crosslinked structure (three-dimensional network structure), and an adhesive with desired cohesion can be obtained .

As the monomer containing a reactive functional group contained in the (meth)acrylate polymer (A) as a monomer unit constituting the polymer, preferably a monomer having a hydroxyl group in the molecule (hydroxyl group-containing Monomers), monomers having carboxyl groups in the molecule (carboxyl group-containing monomers), monomers having amine groups in the molecule (amine group-containing monomers), etc. Among these, hydroxyl-containing monomers that have excellent reactivity with the crosslinking agent (C) and resistance to damp and heat whitening and have less influence on the evil of the electrode are particularly preferred.

Examples of hydroxyl-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 2-hydroxypropyl (meth)acrylate. Hydroxyalkyl (meth)acrylates such as hydroxybutyl, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and the like. Among them, from the viewpoint of the reactivity of the hydroxyl group in the obtained (meth)acrylate polymer (A) with the crosslinking agent (C) and the copolymerizability with other monomers, (meth)acrylic acid 2-hydroxy Ethyl or 4-hydroxybutyl (meth)acrylate is preferred. These can be used alone, or two or more of them can be used in combination.

As the carboxyl group-containing monomer, for example, acrylic acid, methyl propylene Ethylene unsaturated carboxylic acids such as enoic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. Among them, from the viewpoint of the reactivity of the carboxyl group in the (meth)acrylate polymer (A) obtained with the crosslinking agent (C) and the copolymerizability with other monomers, acrylic acid is preferred. These can be used alone, or two or more of them can be used in combination.

Examples of the amine group-containing monomer include aminoethyl (meth)acrylate, n-butylaminoethyl (meth)acrylate, and the like. These can be used alone or in combination of two or more kinds.

The (meth)acrylate polymer (A) preferably contains a hydroxyl-containing monomer with a lower limit of 3% by mass or more as the monomer unit constituting the polymer, and it is particularly preferably containing 10% by mass or more, and the content is 15% by mass. % Or more is more preferable. In addition, the (meth)acrylate polymer (A) preferably contains a hydroxyl-containing monomer with an upper limit value of 35% by mass or less as the monomer unit constituting the polymer, particularly preferably 30% by mass or less. 25% by mass or less is more preferable. If the (meth)acrylate polymer (A) contains a hydroxyl-containing monomer as a monomer unit in the above-mentioned amount, a predetermined amount of hydroxyl groups will remain in the obtained adhesive. Hydroxyl is a hydrophilic group. If the hydrophilic group is present in the adhesive in a predetermined amount, even when the adhesive is placed under high-temperature and high-humidity conditions, it will be compared with the moisture immersed in the adhesive under the high-temperature and high-humidity conditions. The compatibility is also good, and as a result, it is possible to suppress the whitening of the adhesive when it is restored to normal temperature and humidity (excellent heat and humidity resistance to whitening).

As the degree of whitening inhibition, the haze value of the adhesive layer (measured in accordance with JIS K7136: 2000) at normal temperature and humidity after applying high temperature and high humidity conditions is preferably 1.0% or less, particularly preferably 0.9% or less, 0.8% The following are further preferred. In addition, it is preferable that the adhesive layer has a haze value as described above in a normal state. If the haze value is 1.0% or less, the transparency is very high, making it suitable For optical purposes.

However, if a predetermined amount of hydrophilic groups are present in the adhesive as described above, the adhesive will easily absorb water, and migration will easily occur in the electrode in contact with the adhesive. However, the adhesive composition P of this embodiment contains the silane coupling agent (B) having a mercapto group, which can effectively prevent and suppress migration in the electrode in contact.

The (meth)acrylate polymer (A) preferably does not contain a carboxyl group-containing monomer as the monomer unit constituting the polymer, but it is allowed to contain a predetermined amount. This is because, due to the carboxyl-based acid component, there is usually a concern about migration of the target member. However, the adhesive of this embodiment is obtained from the adhesive composition P containing the silane coupling agent (B) having a mercapto group. , It can also exert the migration prevention effect. Specifically, in the (meth)acrylate polymer (A), as a monomer unit, 5 mass% or less of a carboxyl group-containing monomer is contained, and it is preferable to allow the carboxyl group-containing monomer to be contained in an amount of 2 mass% or less .

The (meth)acrylate polymer (A) may contain other monomers as monomer units constituting the polymer as necessary. As other monomers, in order not to hinder the function of the reactive functional group-containing monomer, a monomer that does not contain a reactive functional group is preferred. Examples of such other monomers include (meth)acrylic acid alkoxyalkyl esters such as methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, and (meth)acrylic acid. One of the non-crosslinkable tertiary amino groups such as N,N-dimethylaminoethyl, (meth)acrylate N,N-dimethylaminopropyl, (meth)acryloylmorpholine, etc. (Meth)acrylate, (meth)acrylamide, dimethylacrylamide, vinyl acetate, styrene, etc. These can be used alone or in combination of two or more kinds.

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

The lower limit of the weight average molecular weight of the (meth)acrylate polymer (A) is preferably 200,000 or more, more preferably 300,000 or more, and more preferably 400,000 or more. If the lower limit of the weight average molecular weight of the (meth)acrylate polymer (A) is more than or equal to the above, the adhesive will have excellent step followability under high-temperature and high-humidity conditions. In addition, the weight average molecular weight in this specification is a value in terms of standard polystyrene measured by a gel permeation chromatography (GPC) method.

In addition, the upper limit of the weight average molecular weight of the (meth)acrylate polymer (A) is preferably 1 million or less, more preferably 900,000 or less, and more preferably 700,000 or less. If the upper limit value of the weight average molecular weight of the (meth)acrylate polymer (A) is equal to or less than the above, the adhesive will have an excellent step followability at the time of sticking.

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

(2) Silane coupling agent with mercapto group (B)

The silane coupling agent (B) having a mercapto group is composed of an organosilicon compound having at least one mercapto group and at least one alkoxysilyl group in the molecule. In consideration of the use of the obtained adhesive, it is preferable that the silane coupling agent (B) having a mercapto group has light permeability, for example, one that is substantially transparent.

Specific examples of the silane coupling agent (B) having a mercapto group include 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, and 3-mercaptopropyldimethoxymethylsilane. Low-molecular-weight silane coupling agents containing mercapto groups; 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyldimethoxysilane Co-condensates of methyl silane and other mercapto-containing silane compounds and methyl triethoxy silane, ethyl triethoxy silane, methyl trimethoxy silane, ethyl trimethoxy silane and other alkyl-containing silane compounds Oligomeric silane coupling agents containing sulfhydryl groups, etc. Among them, the mercapto group-containing oligomer-type silane coupling agent with more excellent migration prevention effect and good workability is preferable, and the co-condensate of mercapto group-containing silane compound and alkyl group-containing silane compound is particularly preferable. 3-mercaptopropane The co-condensate of trimethoxysilane and methyltriethoxysilane is further preferred. These can be used alone or in combination of two or more.

The lower limit of the mercapto group equivalent of the organosilicon compound constituting the mercapto group-containing silane coupling agent (B) is preferably 100 g/mole or more, more preferably 120 g/mole or more, and more preferably 150 g/mole or more. By setting the lower limit as described above and setting the difference in polarity with the (meth)acrylate polymer (A) within an appropriate range, the dispersibility of the silane coupling agent (B) in the adhesive can be set The better.

The upper limit of the mercapto group equivalent of the organosilicon compound constituting the mercapto group-containing silane coupling agent (B) is preferably 1000 g/mole or less, more preferably 800 g/mole or less, and more preferably 500 g/mole or less. By setting the upper limit as described above, it is possible to prevent the deterioration of the optical characteristics caused by the phase separation with the (meth)acrylate polymer (A).

The content of the mercapto group-containing silane coupling agent (B) in the adhesive composition P is relative to 100 parts by mass of the (meth)acrylate polymer (A), and the lower limit is preferably 0.01 parts by mass or more, preferably 0.05 by mass Part or more is particularly preferable, and 0.1 part by mass or more is even more preferable. In addition, the upper limit is preferably 5 parts by mass or less, particularly preferably 1.5 parts by mass or less, and 1.0 parts by mass or less is further preferred. good. When the content of the mercapto group-containing silane coupling agent (B) is in the above range, the migration prevention effect is more excellent.

In addition, the lower limit of the number of moles (the amount of mercapto groups) of the mercapto groups in the silane coupling agent (B) per 100 g of the (meth)acrylate polymer (A) is preferably 0.01 mmol or more, especially 0.1 mmol or more Preferably, 0.2 mmol or more is more preferable. In addition, the upper limit of the above-mentioned Mohr number is preferably 30 mmol or less, particularly preferably 5 mmol or less, and more preferably 1.5 mmol or less. When the moire number of the mercapto group of the silane coupling agent (B) with respect to the (meth)acrylate polymer (A) is in the above-mentioned range, the migration prevention effect can be more excellent.

(3) Crosslinking agent (C)

The adhesive composition P preferably contains a crosslinking agent (C). The adhesive composition P contains a crosslinking agent (C) to crosslink the (meth)acrylate polymer (A) to form a three-dimensional network structure, which can increase the cohesive force of the resulting adhesive, thereby further increasing the high temperature Followability of step under high humidity conditions.

As the crosslinking agent (C), what is necessary is to react with the reactive group possessed by the (meth)acrylate polymer (A), and examples include isocyanate-based crosslinking agents and epoxy-based crosslinking agents , Amine-based crosslinking agents, melamine-based cross-linking agents, aziridine-based cross-linking agents, amine-based cross-linking agents, aldehyde-based cross-linking agents, oxazoline-based cross-linking agents, metal alkoxide-based cross-linking agents, Metal chelate-based crosslinking agents, metal salt-based crosslinking agents, ammonium salt-based crosslinking agents, etc. When the (meth)acrylate polymer (A) contains a hydroxyl group-containing monomer as a monomer unit constituting the polymer, it is preferable to use an isocyanate-based crosslinking agent having excellent reactivity with the hydroxyl group. In addition, the crosslinking agent (C) may be used alone or in combination of two or more.

The isocyanate-based crosslinking agent contains at least a polyisocyanate compound By. Examples of the polyisocyanate compound include aromatic polyisocyanates such as toluene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, and isophorone diisocyanate. , Hydrogenated diphenylmethane diisocyanate and other alicyclic polyisocyanates, etc. and such biuret bodies, isocyanurate bodies, as well as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, castor Sesame oil, etc. are used as adducts with reactants of low-molecular-weight active hydrogen compounds. Among them, from the viewpoint of reactivity with hydroxyl groups, trimethylolpropane-modified aromatic polyisocyanates are preferred, and trimethylolpropane-modified toluene diisocyanate is particularly preferred.

The content of the crosslinking agent (C) in the adhesive composition P is relative to 100 parts by mass of the (meth)acrylate polymer (A), and the lower limit is preferably 0.001 parts by mass or more, especially 0.01 parts by mass or more Preferably, 0.02 parts by mass or more is more preferable. In addition, the upper limit is preferably 10 parts by mass or less, particularly preferably 5 parts by mass or less, and more preferably 1 part by mass or less.

When the content of the crosslinking agent (C) is in the above range, the resulting adhesive has better cohesiveness, and the step followability of the adhesive, especially under high temperature and high humidity conditions, is further improved.

(4) Various additives

Various additives commonly used in acrylic adhesives can be added to the adhesive composition P as needed, such as antistatic agents, tackifiers, antioxidants, ultraviolet absorbers, light stabilizers, softeners, fillers, and refractive index Adjusting agent, etc. In addition to the aforementioned silane coupling agent (B) with mercapto group, other silane coupling agents are also added at the same time. However, rust inhibitors, especially benzotriazole-based rust inhibitors, have the effect of inhibiting the crosslinking of the adhesive composition P, so it is preferable not to add them.

In addition, the adhesive composition P refers to a mixture of various components remaining in the original state or reacted state in the adhesive layer. The components removed during the drying process, such as the polymerization solvent and diluting solvent described later, are not included in the adhesive. Sexual composition P.

(5) Manufacturing of adhesive composition

The adhesive composition P can be produced by manufacturing a (meth)acrylate polymer (A) and mixing the obtained (meth)acrylate polymer (A) with a mercapto group-containing silane coupling agent (B), and according to It is manufactured by adding crosslinking agent (C) and additives.

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

Examples of the polymerization initiator include azo compounds, organic peroxides, and the like, and two or more types may be used in combination. As the azo compound, for example, 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-methoxypentane) Nitrile), dimethyl 2,2'-azobis(2-methylpropionate), 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis( 2-hydroxymethylpropionitrile), 2,2'-azobis[2-(2-imidazolin-2-yl)propane] and the like.

Examples of organic peroxides include benzoyl peroxide, tert-butyl peroxybenzoate, cumene hydroperoxide, and diisoperoxydicarbonate. Propyl ester, di-n-propyl peroxydicarbonate, bis(2-ethoxyethyl)peroxydicarbonate, tert-butyl peroxyneodecanoate, tert-butyl peroxypivalate, (3,5 ,5-Trimethylhexyl) peroxide, dipropylene peroxide, diacetyl peroxide, etc.

In addition, in the above-mentioned polymerization process, the weight average molecular weight of the obtained polymer can be adjusted by compounding a chain transfer agent such as 2-mercaptoethanol.

If the (meth)acrylate polymer (A) is obtained, add a mercapto group-containing silane coupling agent (B) and, if necessary, a crosslinking agent (C) to the solution of the (meth)acrylate polymer (A) , The additives and the dilution solvent are mixed thoroughly to obtain the adhesive composition P (coating solution) diluted by the solvent.

As the above-mentioned dilution solvent, for example, aliphatic hydrocarbons such as hexane, heptane, and cyclohexane, aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as dichloromethane and dichloroethane, methanol, ethanol, propanol, etc. are used. Butanol, 1-methoxy-2-propanol and other alcohols, acetone, methyl ethyl ketone, 2-pentanone, isophorone, cyclohexanone and other ketones, ethyl acetate, butyl acetate and other esters, ethyl cellosolve Cellosolve solvents, etc.

The concentration and viscosity of the coating solution prepared in this way are not particularly limited as long as they are within the range that can be coated, and can be appropriately selected according to the situation. For example, it is diluted so that the concentration of the adhesive composition P becomes 10-40% by mass. In addition, when the coating solution is obtained, the addition of a dilution solvent or the like is not a necessary condition, and as long as the adhesive composition P has a coating viscosity or the like, the dilution solvent may not be added. At this time, 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 cross-linking the aforementioned adhesive composition P. The adhesive composition P can be cross-linked by heat treatment. In addition, you can The drying treatment when the diluent solvent or the like of the applied adhesive composition P is volatilized also serves as the heating treatment.

When heat treatment is performed, the heating temperature is preferably 50 to 150°C, particularly 70 to 120°C. In addition, the heating time is preferably 30 seconds to 10 minutes, and particularly preferably 50 seconds to 2 minutes. After the heat treatment, it can be set at normal temperature (for example, 23° C., 50% RH) for an aging period of about 1 to 2 weeks as needed. When the aging period is required, the adhesive layer is formed after the aging period, and when the aging period is not required, the adhesive layer is formed after the heat treatment is completed.

The lower limit of the gel fraction of the adhesive of this embodiment is preferably 30% or more, more preferably 40% or more, and more preferably 50% or more. If the lower limit of the gel fraction of the adhesive is greater than or equal to the above, the cohesive force of the adhesive becomes high, and it becomes one having excellent step followability under high-temperature and high-humidity conditions. In addition, the upper limit of the aforementioned gel fraction is preferably 90% or less, particularly preferably 85% or less, and more preferably 80% or less. If the upper limit value of the gel fraction of the adhesive is equal to or less than the above, the adhesive does not become too hard, and it becomes one having excellent step followability at the time of sticking. Among them, the method for measuring the gel fraction of the adhesive is as shown in the test example described later.

〔Adhesive sheet〕

As shown in Figure 1, the adhesive sheet 1 of this embodiment is composed of two release sheets 12a, 12b; The adhesive layer 11 sandwiched by 12a and 12b. However, the peeling sheets 12a and 12b are not necessarily constituent elements in the adhesive sheet 1, and are those that are peeled and removed when the adhesive sheet 1 is used. In addition, the peeling surface of the peeling sheet in this specification means the surface which has peelability in a peeling sheet, and includes both the surface which performed a peeling process and the surface which showed peelability even if a peeling process was not performed.

(1) Adhesive layer

The adhesive layer 11 is composed of the aforementioned adhesive. The lower limit of the thickness of the adhesive layer 11 (value measured in accordance with JIS K7130) is preferably 10 μm or more, more preferably 25 μm or more, and more preferably 50 μm or more. When the lower limit of the thickness of the adhesive layer 11 is greater than or equal to the above, an excellent adhesive force can be fully exhibited. In addition, the upper limit of the thickness of the adhesive layer 11 is preferably 300 μm or less, particularly preferably 250 μm or less, and more preferably 100 μm or less. When the upper limit value of the thickness of the adhesive layer 11 is the above-mentioned or less, workability becomes favorable. In addition, the adhesive layer 11 may be formed as a single layer, or may be formed by stacking a plurality of layers.

(2) Peeling sheet

The release sheets 12a and 12b are not particularly limited, and a known plastic film can be used. For example, polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film can be used , Polyethylene naphthalate film, polybutylene terephthalate film, polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene‧(meth)acrylic acid copolymer film, ethylene‧(former Base) acrylate copolymer film, polystyrene film, polycarbonate film, polyimide film, fluororesin film, etc. Furthermore, these crosslinked films can also be used. In addition, these laminated films may also be used.

It is preferable that the peeling surface (especially the surface contacting the adhesive layer 11) of the said peeling sheet 12a, 12b has performed a peeling process. Examples of the release agent used in the release treatment include alkyd, silicone, fluorine, unsaturated polyester, polyolefin, and wax release agents. In addition, among the release sheets 12a and 12b, one release sheet is set as a heavy-release type release sheet with a large peeling force, and the other is peeled off. The release sheet is preferably a lightly peelable release sheet with a small peeling force.

The thickness of the release sheets 12a and 12b is not particularly limited, but is usually about 20 to 150 μm.

(3) Manufacturing of adhesive sheets

As an example of the production of the adhesive sheet 1, the above-mentioned coating liquid of the adhesive composition P is applied to the release surface of a release sheet 12a (or 12b), and the adhesive composition P is subjected to heat treatment to crosslink the adhesive composition P to form a coating After layering, the release surface of another release sheet 12b (or 12a) is superimposed on the coating layer. When the curing period is required, the coating layer becomes the adhesive layer 11 by passing the curing period, and when the curing period is not required, the coating layer directly becomes the adhesive layer 11. Thereby, the above-mentioned adhesive sheet 1 is obtained. The heat treatment and aging conditions are as shown above.

As another manufacturing example of the adhesive sheet 1, the above-mentioned coating liquid of the adhesive composition P is applied to the release surface of one release sheet 12a, and the adhesive composition P is subjected to heat treatment to crosslink the adhesive composition P to form a coating layer, thereby A release sheet 12a with a coating layer was obtained. In addition, the coating liquid of the adhesive composition P is applied to the release surface of the other release sheet 12b, and the adhesive composition P is subjected to heat treatment to crosslink the adhesive composition P to form a coating layer, thereby obtaining a peeling with the coating layer片12b. In addition, the release sheet 12a with a coating layer and the release sheet 12b with a coating layer are bonded together so that the two coating layers are in contact with each other. When a curing period is required, the coating layer of the build-up layer becomes the adhesive layer 11 by passing the curing period, and the coating layer of the build-up layer directly becomes the adhesive layer 11 when the curing period is not required. Thereby, the above-mentioned adhesive sheet 1 is obtained. According to this manufacturing example, even when the adhesive layer 11 is thick, it can be manufactured stably.

As a method of applying the coating liquid of the above-mentioned adhesive composition P, For example, a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, a gravure coating method, etc. can be used.

(4) Adhesion

The lower limit of the adhesive force of the adhesive sheet 1 to the soda lime glass of this embodiment is preferably 5N/25mm or more, more preferably 8N/25mm or more, and more preferably 10N/25mm or more. If the lower limit value of the adhesive force of the adhesive sheet 1 is more than the above, it will become a thing excellent in step followability under high temperature and high humidity conditions. On the other hand, the upper limit of the above-mentioned adhesive force is not particularly limited. Considering the ease of peeling of the release sheets 12a, 12b from the adhesive layer 11 during use, etc., 50N/25mm or less is preferred, and 30N/25mm or less is particularly preferred. good. In addition, if reworkability is also considered, 26N/25mm or less is preferable. In this case, even if misfitting occurs, the display component can be easily reused.

Among them, the adhesive force in this specification basically refers to the adhesive force measured by the 180-degree peeling method in accordance with JIS Z0237:2009. After pressing for 20 minutes at 0.5 MPa and 50°C, leave it for 24 hours under the conditions of normal pressure, 23°C and 50% RH, and then measure it at a peeling speed of 300 mm/min.

[Display body]

The display body of the present embodiment includes: a first display body constituent member having a step at least on the surface to be attached; a second display body constituent member; and a first display body constituent member and a second display body constituent member are bonded to each other Bonded adhesive layer. The adhesive layer is composed of the adhesive of the foregoing embodiment. Among them, the first display structural member and/or the second display structural member have an electrode at least on the surface of the bonding side (adhesive layer side). As a preferable structure, the second display body constitutes a member to There is rarely an electrode on the surface to be bonded.

As the display, for example, a liquid crystal (LCD) display, a light emitting diode (LED) display, an organic electroluminescence (organic EL) display, electronic paper, etc. may be mentioned, and it may be a touch panel. In addition, as a display body, it may be a member constituting a part of these.

The first display body constituent member may be a glass plate, a plastic plate, etc., and it is also preferable to be a protective panel composed of a laminate including these. The first display body constituent member has a level difference on the surface on the adhesive layer side, and specifically, it is preferable to have a level difference formed by a printed layer. The printing layer is generally formed in a frame shape.

The glass plate is not particularly limited, and examples include chemically strengthened glass, alkali-free glass, quartz glass, soda lime glass, barium and strontium-containing glass, aluminosilicate glass, lead glass, borosilicate glass, Barium borosilicate glass, etc. The thickness of the glass plate is not particularly limited, but is usually 0.1 to 5 mm, preferably 0.2 to 2 mm.

It does not specifically limit as said plastic board, For example, an acrylic board, a polycarbonate board, etc. are mentioned. The thickness of the plastic plate is not particularly limited, and is usually 0.2-5 mm, preferably 0.4-3 mm.

In addition, various functional layers (electrode layer, silicon oxide layer, hard coat layer, anti-glare layer, etc.) can be provided on one or both sides of the above-mentioned glass plate or plastic plate, and optical members can also be laminated.

The material constituting the printing layer is not particularly limited, and known materials for printing can be used. The thickness of the printed layer, that is, the lower limit of the height of the step, is preferably 3 μm or more, more preferably 5 μm or more, particularly preferably 7 μm or more, and most preferably 10 μm or more. If the lower limit is above the above, it will make the electrical wiring difficult to visually recognize The concealment can be fully ensured by observing from the side of the person. In addition, 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 value below the above, it is possible to prevent the adhesive layer from deteriorating the step followability of the printed layer.

The second display component is an optical member and display module (for example, liquid crystal (LCD) module, light-emitting diode (LED)) module, organic electroluminescence ( Organic EL) modules, etc.), an optical member that is a part of a display module, or a laminate including the display module, preferably has an electrode at least on the surface on the side of the adhesive layer.

Examples of the above-mentioned optical member include electrode films, transparent conductive films, thin film sensors, metal nanowire films, wire grid polarizing films, and the like.

Examples of the above-mentioned electrodes include metal electrodes (including mesh-shaped and grid-shaped ones) made of copper, silver, etc., transparent conductive films (including patterned ones) made of tin-doped indium oxide (ITO), etc., and the like. As described above, among the above-mentioned electrodes, a metal electrode mainly composed of an unoxidized metal, specifically, a metal electrode composed of copper or silver is preferable.

As an example of the display body of this embodiment, a touch panel 2 of the electrostatic capacitance type is shown in FIG. 2. The touch panel 2 is configured to include: a display module 3; a first film sensor 5a layered on top via an adhesive layer 4; and a second film sensor layered on top via the first adhesive layer 11器5b; The covering material 6 laminated on top via the second adhesive layer 11. Since the printed layer 7 is formed on the surface of the cover material 6 on the second adhesive layer 11 side, there is a level difference formed by the presence or absence of the printed layer 7. In this embodiment, the covering material 6 corresponds to the first The display component, and the second film sensor 5b corresponds to the above-mentioned second display component.

At least the second adhesive layer 11 in the touch panel 2 is the adhesive layer 11 of the adhesive sheet 1. If the migration prevention effect is considered, both the first adhesive layer 11 and the second adhesive layer 11 are the above-mentioned adhesives The adhesive layer 11 of the sheet 1 is preferable. In addition, when the first adhesive layer 11 is not the adhesive layer 11 of the above-mentioned adhesive sheet 1, examples of the adhesive constituting the first adhesive layer 11 include acrylic adhesives, rubber-based adhesives, and silicone-based adhesives. Among the adhesives, urethane-based adhesives, polyester-based adhesives, polyvinyl ether-based adhesives, etc., acrylic adhesives are preferred.

The adhesive layer 4 may be formed of the adhesive layer 11 of the above-mentioned adhesive sheet 1, or may be formed of other adhesives or adhesive sheets. In the latter case, as the adhesive constituting the adhesive layer 4, acrylic adhesives, rubber-based adhesives, silicone-based adhesives, urethane-based adhesives, polyester-based adhesives, Among the polyvinyl ether adhesives and the like, acrylic adhesives are preferred.

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

The electrode 52 is composed of, for example, a metal electrode and a patterned transparent conductive film. The metal electrode is composed of copper, silver, or the like. The patterned transparent conductive film is composed of tin-doped indium oxide (ITO) or the like.

The electrode 52 of the first thin-film sensor 5a and the electrode 52 of the second thin-film sensor 5b usually form one circuit pattern in the X-axis direction, and the other Into the circuit pattern in the Y-axis direction.

The electrode 52 of the second thin-film sensor 5b in this embodiment is located on the upper side of the second thin-film sensor 5b in the second figure. On the other hand, the electrode 52 of the first thin film sensor 5a is located on the upper side of the first thin film sensor 5a in Figure 2, but it is not limited to this, and may be located on the lower side of the first thin film sensor 5a. .

Hereinafter, an example of a method of manufacturing the above-mentioned touch panel 2 will be described.

As the adhesive sheet 1, a first adhesive sheet 1 and a second adhesive sheet 1 are prepared. One peeling sheet 12a is peeled off from the first adhesive sheet 1, and the exposed adhesive layer 11 (first adhesive layer) is in contact with the electrode 52 of the first thin film sensor 5a and the first thin film sensor 5a fits. Then, one release sheet 12a is peeled off from the second adhesive sheet 1, and the exposed adhesive layer 11 (second adhesive layer 11) is contacted with the second film in such a way that it contacts the electrode 52 of the second film sensor 5b. The sensor 5b is attached.

And, peel off the other release sheet 12b of the first adhesive sheet, and use the exposed first adhesive layer 11 and the second film sensor 5b on the side opposite to the side on which the second adhesive layer 11 is laminated. The two surfaces (the exposed surface of the base film 51 of the second film sensor 5b) are bonded together so that they are in contact with each other. Thereby, a laminated body in which the release sheet 12b, the second adhesive layer 11, the second film sensor 5b, the first adhesive layer 11, and the first film sensor 5a are laminated in this order is obtained.

Next, the adhesive layer 4 provided on the release sheet is bonded to the surface on the side of the first film sensor 5a of the laminate (the exposed surface of the base film 51 of the first film sensor 5a). Next, the release sheet 12b is peeled off from the laminate, and the covering material 6 is attached to the exposed second adhesive layer 11 so that the printed layer 7 side of the covering material 6 is in contact with the second adhesive layer 11. At this time, the second adhesive layer 11 Since the step followability at the time of sticking is excellent, the generation of gaps and floating near the step formed by the printed layer 7 can be suppressed. By the above bonding, the covering material 6, the second adhesive layer 11, the second film sensor 5b, the first adhesive layer 11, the first film sensor 5a, the adhesive layer 4 and the release sheet can be obtained in this order Layered structure.

Finally, the release sheet is peeled from the above-mentioned structure, and the structure is attached to the display module 3 such that the exposed adhesive layer 4 is in contact with the display module 3. In this way, the touch panel 2 shown in Fig. 2 is manufactured.

Even when the above-mentioned touch panel 2 is placed under high temperature and high humidity conditions and voltage is applied to the electrode 52 in this state, the adhesive layer 11 in contact with the electrode 52 contains a silane coupling agent (B) derived from a mercapto group The composition can effectively suppress the migration of the electrode 52. Thereby, it is possible to prevent the drive failure of the touch panel 2 caused by the disconnection and short-circuit of the electrode 52.

In addition, the adhesive layer 11 has excellent step followability even under high-temperature and high-humidity conditions. Therefore, even when the touch panel 2 is exposed to high-temperature and high-humidity conditions for a predetermined period of time (for example, 72 hours at 85°C and 85% RH) In this case, it is also possible to effectively suppress the generation of bubbles, floating, peeling, etc. in the vicinity of the step formed by the printed layer 7.

The embodiments described above are described in order to facilitate the understanding of the present invention, and are not described in order to limit the present invention. Therefore, the requirements disclosed in the above embodiments also include all design changes and equivalents to which the technical scope of the present invention belongs.

For example, any one of the release sheets 12a and 12b in the adhesive sheet 1 may be omitted.

[Examples]

Hereinafter, the present invention will be further specifically described with examples and the like, but the scope of the present invention is not limited to these examples and the like.

[Example 1]

1. Preparation of (meth)acrylate copolymer

60 parts by mass of 2-ethylhexyl acrylate, 20 parts by mass of methyl methacrylate, and 20 parts by mass of 2-hydroxyethyl acrylate were copolymerized to prepare a (meth)acrylate polymer (A). As a result of measuring the molecular weight of the (meth)acrylate polymer (A) by the method described below, the weight average molecular weight (Mw) was 600,000.

2. Preparation of adhesive composition

100 parts by mass of the (meth)acrylate polymer (A) obtained in the above process 1 (solid content conversion value; the same below), and 3-mercaptopropyltrimethoxy as a silane coupling agent (B) having a mercapto group Co-condensate of methyl silane and methyl triethoxy silane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "X-41-1810", oligomer type, mercapto group equivalent: 450g/mole) 0.05 0.23 parts by mass of trimethylolpropane-modified toluene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., product name "Coronate L") as the crosslinking agent (C), mixed and fully stirred, and used The methyl ethyl ketone was diluted to obtain a coating solution of an adhesive composition having a solid content of 38% by mass.

Among them, each compounding (solid content conversion value) of the adhesive composition when the (meth)acrylate polymer (A) is set to 100 parts by mass (solid content conversion value) is shown in Table 1. In addition, the details of the abbreviations and the like described in Table 1 are as follows.

[(Meth)acrylate polymer (A)]

2EHA: 2-ethylhexyl acrylate

MMA: methyl methacrylate

HEA: 2-hydroxyethyl acrylate

[Silane coupling agent with mercapto group (B)]

X-41-1810: Co-condensate of 3-mercaptopropyltrimethoxysilane and methyltriethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "X-41-1810", oligomer) Polymer type, sulfhydryl equivalent: 450g/mol)

KBM-803: 3-mercaptopropyl trimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBM-803", low molecular weight type, mercapto equivalent weight: 196.4 g/mole)

[Other Silane Coupling Agents]

KBM-403: 3-glycidoxypropyl trimethoxysilane (manufactured by Shin-Etsu Silicone Co., Ltd., trade name "KBM-403", low molecular weight type)

KBE-9007: 3-isocyanate propyl triethoxysilane (manufactured by Shin-Etsu Silicone Co., Ltd., trade name "KBE-9007", low molecular weight type)

3. Manufacture of Adhesive Sheet

The peeling treatment of a heavy peeling type release sheet (manufactured by LINTEC Corporation, trade name "SP-PET382150", thickness: 38μm) obtained by peeling one side of the polyethylene terephthalate film with a silicone-based release agent On the surface, the coating solution of the adhesive composition obtained in the above process 2 was coated with a knife coater, and then heat-treated at 90° C. for 1 minute to form a coating layer (thickness: 25 μm). Similarly, the peeling treatment surface of a lightly peelable peeling sheet (manufactured by LINTEC Corporation, product name "SP-PET382120") obtained by peeling off one side of a polyethylene terephthalate film with a silicone-based peeling agent Above, use a knife coater to coat the adhesiveness obtained in process 2 above After the coating solution of the composition, it was heat-processed at 90 degreeC for 1 minute, and the coating layer (thickness: 25 micrometers) was formed.

Next, the heavy release release sheet with a coating layer obtained in the above and the light release release sheet with a coating layer obtained in the above are bonded so that the two coating layers are in contact with each other, and the After curing for 7 days under the conditions of 23° C. and 50% RH, an adhesive sheet composed of a heavy peeling type release sheet/adhesive layer (thickness: 50 μm)/light peeling type peeling sheet was produced.

[Examples 2-10, Comparative Examples 1-10]

As shown in Table 1, the type and ratio of the silane coupling agent (the silane coupling agent having a mercapto group (B) and other silane coupling agents) and the ratio of the crosslinking agent (C) were changed in the same manner as in Example 1, except that Manufacture adhesive sheets. In addition, for Comparative Examples 7 to 10, N,N-bis(2-ethylhexyl)-(4 or 5)-methyl-1H-benzotriazole-1-methylamine (manufactured by BASF Corporation, trade name "IRGMET 39") was blended into the adhesive composition at the ratio shown in Table 1 as a rust inhibitor.

Here, the aforementioned weight average molecular weight (Mw) is a weight average molecular weight in terms of polystyrene measured (GPC measurement) using gel permeation chromatography (GPC) under the following conditions.

<Measurement conditions>

‧GPC measuring device: manufactured by TOSOH CORPORATION, HLC-8020

‧GPC column (pass in the following order): TOSOH CORPORATION

TSK guard column HXL-H

TSK gel GMHXL(×2)

TSK gel G2000HXL

‧Measuring solvent: Tetrahydrofuran

‧Measuring temperature: 40℃

[Test Example 1] (Measurement of Gel Fraction)

The adhesive sheets obtained in the examples and comparative examples were cut into a size of 80mm×80mm, the adhesive layer was wrapped in a polyester mesh (mesh size 200), and the mass was weighed by a precision balance and subtracted The mass of the above net alone is used to calculate the mass of the adhesive itself. Let the mass at this time be M1.

Next, at room temperature (23°C), the adhesive wrapped in the polyester net was immersed in ethyl acetate for 24 hours. After that, the adhesive was taken out and air-dried for 24 hours in an environment with a temperature of 23°C and a relative humidity of 50%, and in addition, it was dried in an oven at 80°C for 12 hours. After drying, the mass is weighed by a precision balance, and the mass of the net alone is subtracted to calculate the mass of the adhesive itself. Let the mass at this time be M2. (M2/M1)×100 represents the gel rate (%). The results are shown in Table 2.

[Test Example 2] (Measurement of Adhesion)

The light-peelable release sheet was peeled off from the adhesive sheets obtained in the Examples and Comparative Examples, and the exposed adhesive layer was attached to a polyethylene terephthalate (PET) film (TOYOBO CO. , LTD., product name "PET A4300", thickness: 100μm) easy-to-adhesive layer to obtain a laminate of heavy-peelable release sheet/adhesive layer/PET film. The obtained laminate was cut into a width of 25 mm and a length of 100 mm, and this was used as a sample.

In an environment of 23°C and 50% RH, the heavy-peelable release sheet was peeled from the above sample, and the exposed adhesive layer was attached to soda lime glass (manufactured by Nippon Sheet Glass Co., Ltd.), and then used KURIHARA CORPORATION Make an autoclave and pressurize it at 0.5MPa and 50°C for 20 minutes. Thereafter, at 23 After leaving for 24 hours under the conditions of ℃ and 50%RH, the adhesion force (N/25mm ). Conditions other than those described here are measured in compliance with JIS Z 0237:2009. The results are shown in Table 2.

[Test Example 3] (Evaluation of migration prevention effect)

(1) Production of wiring board

The copper of the copper clad laminate (manufactured by NIKKAN INDUSTRIES Co., Ltd., product name "NIKAFLEX") formed by laminating copper foil (thickness: 18μm) and polyethylene terephthalate film (thickness: 50μm) On the surface of the foil, an etching resist pattern is printed using a screen printing method. After that, unnecessary copper foil is removed by etching to form comb-shaped electrodes. The line width of each electrode is 300 μm, and the gap between the electrodes is 50 μm.

(2) Evaluation of migration prevention effect

The light-peelable release sheet was peeled off from the adhesive sheets obtained in the Examples and Comparative Examples, and the exposed adhesive layer was attached to a polyethylene terephthalate (PET) film (TOYOBO CO. , LTD., product name "PET A4300", thickness: 100μm) easy-to-adhesive layer to obtain a laminate of heavy-peelable release sheet/adhesive layer/PET film. Next, the heavy-peelable release sheet was peeled off from the laminate, and the exposed adhesive layer was attached to the comb-shaped electrode, which was used as a sample.

The above-mentioned sample was allowed to stand still under the moist heat conditions of 85° C. and 85% RH, and in this state, a voltage of 5 V was applied between the electrodes to perform a migration test. After 8 hours, 24 hours, and 48 hours from the start of the test, the comb-shaped electrode was observed with an optical microscope (magnification: 10 times) and evaluated based on the evaluation criteria shown below Migration prevention effect. The results are shown in Table 2.

⊚: The dissolution of the electrode (positive electrode) and the formation of dendrites in the electrode (negative electrode) are not observed at all.

○: Dissolution was observed only at the end of the electrode (positive electrode), and the formation of dendrites in the electrode (negative electrode) was not observed.

×: Dissolution of the electrode (positive electrode) and formation of dendrites in the electrode (negative electrode) are observed.

In addition, the reference image of the aforementioned evaluation criteria is shown in Fig. 3.

[Test Example 4] (Evaluation of the followability of the step)

(a) Preparation of evaluation samples

Screen printing ultraviolet curable ink (Teikoku Printing Inks Mfg. Co., Ltd., product name "POS-911 ink"), so that the coating thickness becomes a frame shape of any of 5 μm, 10 μm, and 15 μm (outer shape: vertical 90 mm × horizontal 50 mm, width 5 mm). Then, irradiate ultraviolet rays (80W/cm ² , two metal halide lamps, lamp height of 15cm, belt speed of 10~15m/min) to harden the above-mentioned ultraviolet-curable ink for printing, so as to produce A glass plate with a step (the height of the step: any one of 5μm, 10μm and 15μm) with a step.

The light-peelable release sheet was peeled off from the adhesive sheets obtained in the examples and comparative examples, and the exposed adhesive layer was attached to a polyethylene terephthalate film with an easy-adhesive layer (TOYOBO Co., Ltd.) .Manufacturing, PET A4300, thickness: 100μm) easy-to-bond layer. Next, peel off the heavy peeling type release sheet, and peel off the pre-curing adhesive layer. After that, a plastic packaging machine (manufactured by FUJIPLA Inc., Product name "LPD3214") The laminated body is plastic-sealed on each glass plate with a step in such a way that the adhesive layer covers the entire printing surface of the frame shape.

(b) Evaluation of evaluation samples

Under the conditions of 50°C and 0.5MPa, the obtained evaluation sample was autoclaved for 30 minutes, and then placed under normal pressure, 23°C, and 50%RH for 24 hours. Then, it was stored for 72 hours under durable conditions of 85° C. and 85% RH. After that, the adhesive layer (especially the vicinity of the step formed by the printed layer) was visually confirmed, and the step followability was evaluated according to the following criteria. The results are shown in Table 2.

◎: There is no air bubbles or floating at all.

○: Less than 10 bubbles are observed in the vicinity of the level difference.

×: Air bubbles and/or floating are present.

[Test Example 5] (Evaluation of resistance to damp and heat whitening)

The adhesive layer of the adhesive sheet obtained in the example or the comparative example was sandwiched between two sheets of non-alkali glass with a thickness of 1.1 mm to obtain a laminate, which was used as a sample. Store the obtained sample for 120 hours under the conditions of 85°C and 85%RH. After that, the normal temperature and humidity of 23° C. and 50% RH were restored, the presence or absence of whitening was visually confirmed according to the following criteria, the wet heat whitening resistance was evaluated, and the haze value of the adhesive layer was measured. The haze value was measured within 30 minutes after returning the sample to normal temperature and humidity using a haze meter (manufactured by NIPPON DENSHOKU INDUSTRIES Co., LTD., product name "NDH2000") in accordance with JIS K7136:2000. The results are shown in Table 2.

○: Even if normal temperature and humidity are restored, whitening is not confirmed. Or, a part of the bleaching occurs, but it disappears within 30 minutes.

×: The whole is whitened. Or, after a part of it has been whitened, it cannot be restored to its original state even if it is stored under normal temperature and humidity.

It can be seen from Table 2 that the pressure-sensitive adhesive sheet obtained in the examples was excellent in any of the effect of preventing migration, the step-following property, and the resistance to damp heat whitening.

[Industrial availability]

The adhesive composition, adhesive, and adhesive sheet of the present invention can be preferably used, for example, in a touch panel of an electrostatic capacitance type using a copper electrode or a silver electrode. In addition, the display of the present invention is preferably used as, for example, a touch panel of an electrostatic capacitance type using copper electrodes or silver electrodes.

1‧‧‧Adhesive sheet

11‧‧‧Adhesive layer before hardening

12a、12b‧‧‧Release sheet

Claims (8)

An adhesive composition forming an adhesive for bonding a first display body constituent member and a second display body constituent member having a step at least on the surface of the bonding side, characterized by: the aforementioned first display body constituent member and / Or the aforementioned second display body constituent member has an electrode at least on the bonding side surface, and the aforementioned adhesive composition contains: a (meth)acrylate polymer (A); and a mercapto group-containing silane coupling agent (B), the aforementioned The (meth)acrylate polymer (A) contains 15% by mass or more and 35% by mass or less of a hydroxyl-containing monomer as the monomer unit constituting the polymer, and constitutes the organic compound of the aforementioned mercapto-containing silane coupling agent (B) The mercapto group equivalent of the silicon compound is 100 g/mol or more and 1000 g/mol or less. The adhesive composition described in item 1 of the scope of the patent application, wherein the aforementioned sulfhydryl group-containing silane coupling agent (B) is a sulfhydryl group-containing oligomer type silane coupling agent. The adhesive composition as described in claim 1, wherein the content of the mercapto group-containing silane coupling agent (B) in the adhesive composition is relative to the (meth)acrylate polymer (A) 100 parts by mass is 0.01 parts by mass or more and 5 parts by mass or less. The adhesive composition described in claim 1, wherein the adhesive composition further contains a crosslinking agent (C). An adhesive formed by cross-linking the adhesive composition described in any one of items 1 to 4 in the scope of the patent application. An adhesive sheet having an adhesive layer composed of the adhesive described in item 5 of the scope of patent application. The adhesive sheet according to claim 6, wherein the adhesive sheet includes two peeling sheets, and the adhesive layer is sandwiched by the peeling sheet so as to be in contact with the peeling surfaces of the two peeling sheets. A display body comprising: a first display body constituent member having a level difference at least on the surface of the bonding side; a second display body constituent member; and an adhesive layer, which constitutes the first display body constituent member and the second display body The members are adhered to each other, and the display is characterized in that the first display structural member and/or the second display structural member has an electrode at least on the surface on the bonding side, and the adhesive layer is the sixth item in the scope of patent application. The adhesive layer of the adhesive sheet.

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