JP2017014378A - Migration inhibitor, adhesive and adhesive sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a migration inhibitor capable of effectively preventing and inhibiting migration, an adhesive and an adhesive sheet.SOLUTION: There are provided a migration inhibitor containing a silane coupling agent having a mercapto group, an adhesive obtained from an adhesive composition containing the migration inhibitor and an adhesive sheet 1 having an adhesive layer 11 consisting of the adhesive. The adhesive composition preferably contains a (meth)acrylic acid ester polymer (A) and the silane coupling agent having the mercapto group (B) as the migration inhibitor.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a migration inhibitor, a pressure-sensitive adhesive, and a pressure-sensitive adhesive sheet that can prevent / suppress migration of a metal member, for example, a metal electrode of a touch panel.

  In various mobile electronic devices such as smartphones and tablet terminals in recent years, a touch panel is often used as a display. As a touch panel method, there are a resistive film method, a capacitance method, and the like. In the mobile electronic device as described above, a capacitance method is mainly adopted.

  Recently, the touch panel has been increased in size, and meshed metal electrodes such as a copper electrode and a silver electrode have been studied as electrode materials for the touch panel. However, when a conventional pressure-sensitive adhesive is used in contact with a metal electrode, particularly a copper electrode or a silver electrode, ion migration (= electrochemical migration; hereinafter simply referred to as “migration”) may occur. Specifically, in the positive electrode, the electrode is melted and disconnected, or in the negative electrode, dendrite is formed due to deposition of the positive electrode component, resulting in a short circuit.

  This migration is particularly likely to occur when a voltage is applied to the electrode under high temperature and high humidity. When such migration occurs, the touch panel cannot be driven normally. Particularly, in recent years when miniaturization of electrodes and narrowing of the pitch are progressing, disconnection / short-circuiting of electrodes due to migration is likely to occur.

  By the way, Patent Document 1 discloses a pressure-sensitive adhesive composition for a touch panel containing a benzotriazole compound as a rust preventive.

JP 2014-177611 A

  However, even though the benzotriazole compound as a rust preventive has the effect of preventing corrosion of metal wiring, it has not been able to sufficiently prevent or suppress migration.

  This invention is made | formed in view of the above actual conditions, and it aims at providing the migration inhibitor, adhesive, and adhesive sheet which can prevent and suppress migration effectively.

  In order to achieve the above object, first, the present invention provides a migration inhibitor characterized by containing a silane coupling agent having a mercapto group (Invention 1).

  According to the above invention (Invention 1), when the material to which the migration inhibitor is added comes into contact with a target member such as a metal member, for example, a metal electrode of a touch panel, migration in the target member is effectively prevented. -It can be suppressed.

  In the said invention (invention 1), it is preferable that the said silane coupling agent is a mercapto group containing oligomer type silane coupling agent (invention 2).

  In the said invention (invention 1 and 2), it is preferable that the mercapto group equivalent of the organosilicon compound which comprises the said silane coupling agent is 100 g / mol or more and 1000 g / mol or less (invention 3).

  2ndly this invention provides the adhesive obtained from the adhesive composition containing the said migration inhibitor (invention 1-3) (invention 4).

  In the said invention (invention 4), the said adhesive composition contains the (meth) acrylic acid ester polymer (A) and the silane coupling agent (B) which has a mercapto group as said migration inhibitor. (Invention 5)

  In the said invention (invention 5), it is preferable that the said (meth) acrylic acid ester polymer (A) contains 3 to 35 mass% of hydroxyl-containing monomers as a monomer unit which comprises the said polymer. (Invention 6).

  In the said invention (invention 5 and 6), it is preferable that the said adhesive composition contains a crosslinking agent (C) further (invention 7).

  In the said invention (invention 5-7), content of the said silane coupling agent (B) which has the said mercapto group in the said adhesive composition is 100 mass parts of said (meth) acrylic acid ester polymers (A). On the other hand, it is preferable that it is 0.01 to 5 mass parts (invention 8).

  Thirdly, the present invention includes two release sheets and an adhesive layer sandwiched between the release sheets so as to be in contact with the release surfaces of the two release sheets, and the adhesive layer is the adhesive. A pressure-sensitive adhesive sheet comprising (Inventions 4 to 8) is provided (Invention 9).

  In the said invention (invention 9), it is preferable that the said adhesive layer is arrange | positioned so that an electrode may be contacted in a touch panel (invention 10).

  According to the migration inhibitor, the pressure-sensitive adhesive, and the pressure-sensitive adhesive sheet according to the present invention, migration can be effectively prevented / suppressed.

It is sectional drawing of the adhesive sheet which concerns on one Embodiment of this invention. It is sectional drawing which shows one structural example of a touchscreen. 12 is a reference image of an evaluation standard in evaluating the migration prevention effect of Test Example 3.

Hereinafter, embodiments of the present invention will be described.
[Migration inhibitor]
The migration inhibitor according to one embodiment of the present invention contains a silane coupling agent having a mercapto group. The migration inhibitor according to this embodiment may be composed of only a silane coupling agent having a mercapto group, or may contain other components.

  The migration inhibitor according to the present embodiment is added to a material (hereinafter also referred to as “contact material”) in contact with a member (hereinafter also referred to as “target member”) that is required to prevent / suppress migration. Preferably used. Examples of target members include metal electrodes (including mesh-like ones) made of copper, silver, etc., transparent conductive films (including patterned ones) made of tin-doped indium oxide (ITO), metal nanowire films, Examples thereof include a wire grid polarizing film. Among the metal electrodes, it is preferable to use a metal electrode whose main component is an unoxidized metal, specifically, a metal electrode made of copper or silver. Moreover, as said contact material, an adhesive agent, a hard-coat agent, etc. other than the adhesive mentioned later are mentioned, for example.

  The silane coupling agent having a mercapto group can prevent and suppress the dissolution of the electrode at the positive electrode when the contact material to which the migration inhibitor containing the silane coupling agent is added contacts the target member. In addition, it is possible to prevent and suppress the formation of dendrites at the negative electrode. That is, migration in the target member can be effectively prevented / suppressed (this effect may be referred to as “migration prevention effect”). Thereby, for example, even in a target member in which the electrodes are miniaturized and the pitch is reduced, disconnection or short-circuiting of the electrodes can be prevented. In particular, when the target member is an electrode of a touch panel, it is possible to prevent a touch panel drive failure due to electrode disconnection or short circuit.

  The silane coupling agent 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 the case where the target member is an optical member such as a touch panel, the silane coupling agent having a mercapto group is preferably light transmissive, for example, substantially transparent.

  Specific examples of the silane coupling agent having a mercapto group include mercapto group-containing low molecular silane coupling agents such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, and 3-mercaptopropyldimethoxymethylsilane; Mercapto group-containing silane compounds such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyldimethoxymethylsilane, methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, ethyltrimethoxy Examples include a mercapto group-containing oligomer type silane coupling agent such as a cocondensate with an alkyl group-containing silane compound such as silane. Among them, a mercapto group-containing oligomer type silane coupling agent which is excellent in migration prevention effect and good workability is preferable, and a co-condensate of a mercapto group-containing silane compound and an alkyl group-containing silane compound is particularly preferable, and 3-mercapto is more preferable. A cocondensate of propyltrimethoxysilane and methyltriethoxysilane is preferred. These may be used individually by 1 type and may be used in combination of 2 or more type.

  The lower limit of the mercapto group equivalent of the organosilicon compound constituting the silane coupling agent having a mercapto group is preferably 100 g / mole or more, particularly preferably 120 g / mole or more, and more preferably 150 g / mole or more. It is preferable that By setting the lower limit as described above, when the contact material is used as a pressure sensitive adhesive, the polarity difference from the main polymer component is within an appropriate range, and the silane coupling agent is dispersed in the pressure sensitive adhesive. The property can be made suitable.

  The upper limit of the mercapto group equivalent of the organosilicon compound constituting the silane coupling agent having a mercapto group is preferably 1000 g / mol or less, particularly preferably 800 g / mol or less, and more preferably 500 g / mol or less. It is preferable that By setting the upper limit as described above, when the contact material is used as a pressure sensitive adhesive, it is possible to prevent deterioration of optical characteristics due to phase separation from the polymer component as the main agent.

  The amount of migration inhibitor added to the contact material is preferably such that the lower limit of the content of the component derived from the silane coupling agent having a mercapto group in the contact material is 0.01% by mass or more. In particular, the amount is preferably 0.05% by mass or more, and more preferably 0.1% by mass or more. Further, the addition amount is preferably such an amount that the upper limit of the content of the above-mentioned components in the contact material is 5% by mass or less, particularly preferably 2.5% by mass or less, Furthermore, the amount is preferably 1% by mass or less. When the addition amount of the migration inhibitor is in the above range, the migration prevention effect is more excellent.

[Adhesive]
The pressure-sensitive adhesive according to this embodiment is obtained from a pressure-sensitive adhesive composition containing the migration inhibitor described above. The type of pressure-sensitive adhesive is not particularly limited as long as the migration-preventing effect by the migration-preventing agent is exhibited. For example, acrylic pressure-sensitive adhesive, rubber-based pressure-sensitive adhesive, silicone-based pressure-sensitive adhesive, urethane-based pressure-sensitive adhesive, polyester-based Any of pressure-sensitive adhesive, polyvinyl ether-based pressure-sensitive adhesive, and the like may be used. The pressure-sensitive adhesive may be any of an emulsion type, a solvent type, or a solventless type, and may be a crosslinked type or a non-crosslinked type. Furthermore, either an active energy ray curable type or an active energy ray non-curable type may be used.

  When the target member is an electrode of a touch panel, an acrylic adhesive is preferable among the above. In that case, the pressure-sensitive adhesive according to the present embodiment contains a (meth) acrylic acid ester polymer (A) and a silane coupling agent (B) having a mercapto group as the migration inhibitor. It is preferable to be obtained from a product (hereinafter sometimes referred to as “adhesive composition P”). The pressure-sensitive adhesive composition P preferably further contains a cross-linking agent (C). In that case, the pressure-sensitive adhesive according to this embodiment is obtained by cross-linking the pressure-sensitive adhesive composition P. In this specification, (meth) acrylic acid ester means both acrylic acid ester and methacrylic acid ester. The same applies to other similar terms. Further, the “polymer” includes the concept of “copolymer”.

  The pressure-sensitive adhesive layer composed of the pressure-sensitive adhesive composition P containing the silane coupling agent (B) having a mercapto group not only exhibits the migration prevention effect described above, but also at the interface with the target member. Due to the presence of the component derived from the silane coupling agent (B) having a mercapto group, the adhesion with the target member is high, and when the target member has a step, the step following property is excellent. Specifically, even if the pressure-sensitive adhesive layer is applied to a target member having a step and exposed to a high temperature and high humidity condition for a predetermined time (for example, 85 ° C. and 85% RH for 72 hours), the step Occurrence of bubbles, floats, peeling, etc. in the vicinity is suppressed (excellent step following property under high temperature and high humidity conditions). Thereby, when a target member is a touch panel, it is suppressed that the reflection loss of light arises near a level difference, and it can maintain the picture quality of a touch panel favorably.

(1) (Meth) acrylic acid ester polymer (A)
The (meth) acrylic acid ester polymer (A) contains a (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group as a monomer unit constituting the polymer. Can be expressed. From such a viewpoint, the (meth) acrylic acid ester polymer (A) has a lower limit of 50 (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms as the monomer unit constituting the polymer. It is preferably contained in an amount of at least mass%, particularly preferably at least 60 mass%, more preferably at least 70 mass%. When the (meth) acrylic acid alkyl ester is contained in an amount of 50% by mass or more, the (meth) acrylic acid ester polymer (A) can exhibit suitable tackiness. The (meth) acrylic acid ester polymer (A) preferably contains 97% by mass or less of the above (meth) acrylic acid alkyl ester as a monomer unit constituting the polymer, and particularly 90% by mass. % Or less, preferably 85% by mass or less. By containing 97% by mass or less of the (meth) acrylic acid alkyl ester, a suitable amount of other monomer components can be introduced into the (meth) acrylic acid ester polymer (A).

  Examples of the (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and (meth) acrylic acid n-. Butyl, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, n-decyl (meth) acrylate, (meth) acrylic acid n-dodecyl, myristyl (meth) acrylate, palmityl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, adamantyl (meth) acrylate, etc. Among these, from the viewpoint of further improving the adhesiveness, the alkyl group having 4 to 8 carbon atoms is a (meth) a. It is preferred to include acrylic acid esters. These may be used alone or in combination of two or more. In addition, the alkyl group in the (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group refers to a linear, branched or cyclic alkyl group.

  Further, as a (meth) acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms, a hard monomer having a glass transition temperature (Tg) exceeding 0 ° C. (preferably 70 ° C. or more) as a homopolymer, and a homopolymer It is also preferable to use in combination with a soft monomer having a glass transition temperature (Tg) of 0 ° C. or less. This is because the step followability in the display panel (touch panel) can be further improved by improving the cohesive force with the hard monomer while ensuring the adhesiveness and flexibility with the soft monomer. In this case, the mass ratio of the hard monomer to the soft monomer is preferably 5:95 to 40:60, and particularly preferably 20:80 to 30:70.

  Examples of the hard monomer include methyl acrylate (Tg 10 ° C.), methyl methacrylate (Tg 105 ° C.), isobornyl acrylate (Tg 94 ° C.), isobornyl methacrylate (Tg 180 ° C.), adamantyl acrylate (Tg 115 ° C.), and methacrylic acid. And adamantyl (Tg 141 ° C.). These may be used alone or in combination of two or more.

  Among the hard monomers, methyl acrylate, methyl methacrylate, and isobornyl acrylate are preferable from the viewpoint of further exerting the performance of the hard monomer while preventing adverse effects on other properties such as adhesiveness and transparency. In view of tackiness, methyl acrylate and methyl methacrylate are more preferable, and methyl methacrylate is particularly preferable.

  Preferable examples of the soft monomer include acrylic acid alkyl esters having a linear or branched alkyl group having 2 to 12 carbon atoms. For example, 2-ethylhexyl acrylate (Tg-70 ° C.), n-butyl acrylate (Tg-54 ° C.) and the like are preferable. These may be used alone or in combination of two or more.

  The (meth) acrylic acid ester 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 a cross-linking agent (C) described later, thereby forming a cross-linked structure (three-dimensional network structure) to obtain a pressure-sensitive adhesive having a desired cohesive force. It is done.

  The reactive functional group-containing monomer contained in the (meth) acrylic acid ester polymer (A) as a monomer unit constituting the polymer includes a monomer having a hydroxyl group in the molecule (hydroxyl group-containing monomer) and a carboxyl in the molecule. Preferred examples include a monomer having a group (carboxyl group-containing monomer) and a monomer having an amino group in the molecule (amino group-containing monomer). Among these, a hydroxyl group-containing monomer that is excellent in reactivity with the cross-linking agent (C) and moist heat and whitening resistance and has little adverse effect on the target member is particularly preferable.

  Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, (meth And (meth) acrylic acid hydroxyalkyl esters such as 3-hydroxybutyl acrylate and 4-hydroxybutyl (meth) acrylate. Among them, 2-hydroxyethyl (meth) acrylate in terms of reactivity with the crosslinking agent (C) of the hydroxyl group in the obtained (meth) acrylic acid ester polymer (A) and copolymerization with other monomers. Or 4-hydroxybutyl (meth) acrylate is preferable. These may be used alone or in combination of two or more.

  Examples of the carboxyl group-containing monomer include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. Of these, acrylic acid is preferred from the viewpoint of the reactivity of the resulting (meth) acrylic acid ester polymer (A) with the crosslinking agent (C) of the carboxyl group and the copolymerizability with other monomers. These may be used alone or in combination of two or more.

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

  The (meth) acrylic acid ester polymer (A) preferably contains a hydroxyl group-containing monomer as a lower limit of 3% by mass or more, particularly 10% by mass or more, as a monomer unit constituting the polymer. More preferably, it is preferably contained in an amount of 15% by mass or more. Further, the (meth) acrylic acid ester polymer (A) preferably contains a hydroxyl group-containing monomer as an upper limit value of 35% by mass or less, particularly 30% by mass or less, as a monomer unit constituting the polymer. It is preferable that the content is 25% by mass or less. When the (meth) acrylic acid ester polymer (A) contains a hydroxyl group-containing monomer in the above amount as a monomer unit, a predetermined amount of hydroxyl group remains in the resulting adhesive. A hydroxyl group is a hydrophilic group, and when such a hydrophilic group is present in a pressure-sensitive adhesive, even if the pressure-sensitive adhesive is placed under a high temperature and high humidity condition, it penetrates into the pressure sensitive adhesive under the high temperature and high humidity condition. As a result, the whitening of the pressure-sensitive adhesive when it is returned to room temperature and normal humidity is suppressed (excellent moisture and heat whitening resistance).

  However, when a predetermined amount of the hydrophilic group is present in the pressure-sensitive adhesive as described above, the pressure-sensitive adhesive easily takes in water, and migration tends to occur in the target member that contacts the pressure-sensitive adhesive. However, the pressure-sensitive adhesive composition P according to the present embodiment effectively contains the migration of the target member to be contacted by containing the silane coupling agent (B) having a mercapto group as a migration inhibitor. It can be prevented / suppressed.

  The (meth) acrylic acid ester polymer (A) preferably does not contain a carboxyl group-containing monomer as a monomer unit constituting the polymer, but is allowed to contain a predetermined amount. Since the carboxyl group is an acid component, the migration of the target member is usually a concern. However, the pressure-sensitive adhesive according to this embodiment contains a silane coupling agent (B) having a mercapto group as a migration inhibitor. This is because, by being obtained from the composition P, even if a carboxyl group is present, the effect of preventing migration can be exhibited. Specifically, it is allowed to contain a carboxyl group-containing monomer in the (meth) acrylic acid ester polymer (A) as a monomer unit in an amount of 5% by mass or less, preferably 2% by mass or less.

  The (meth) acrylic acid ester polymer (A) may contain other monomers as monomer units constituting the polymer, if desired. The other monomer is preferably a monomer that does not contain a reactive functional group so as not to interfere with the action of the reactive functional group-containing monomer. Examples of such other monomers include (meth) acrylic acid alkoxyalkyl esters such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, (meth) ) N, N-dimethylaminopropyl acrylate, (meth) acrylic acid ester having a non-crosslinkable tertiary amino group such as (meth) acryloylmorpholine, (meth) acrylamide, dimethylacrylamide, vinyl acetate, styrene, etc. It is done. These may be used alone or in combination of two or more.

  The polymerization mode of the (meth) acrylic acid ester polymer (A) may be a random copolymer or a block copolymer.

  The lower limit of the weight average molecular weight of the (meth) acrylic acid ester polymer (A) is preferably 200,000 or more, particularly preferably 300,000 or more, and more preferably 400,000 or more. In addition, the weight average molecular weight in this specification is the value of standard polystyrene conversion measured by the gel permeation chromatography (GPC) method. When the lower limit of the weight average molecular weight of the (meth) acrylic acid ester polymer (A) is not less than the above, the pressure-sensitive adhesive has excellent step following ability under high temperature and high humidity conditions.

  The upper limit of the weight average molecular weight of the (meth) acrylic acid ester polymer (A) is preferably 1,000,000 or less, particularly preferably 900,000 or less, and more preferably 700,000 or less. preferable. When the upper limit value of the weight average molecular weight of the (meth) acrylic acid ester polymer (A) is not more than the above, the pressure-sensitive adhesive has excellent step following ability at the time of sticking.

  In the adhesive composition P, the (meth) acrylic acid ester polymer (A) may be used singly or in combination of two or more.

(2) Silane coupling agent having a mercapto group (B)
The silane coupling agent (B) having a mercapto group contained in the adhesive composition P is a silane coupling agent having a mercapto group as the migration inhibitor described above.

  Content of the silane coupling agent (B) which has a mercapto group in the adhesive composition P is 0.01 mass part or more as a lower limit with respect to 100 mass parts of (meth) acrylic acid ester polymer (A). In particular, it is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more. Moreover, it is preferable that it is 5 mass parts or less as an upper limit, It is especially preferable that it is 1.5 mass parts or less, Furthermore, it is preferable that it is 1.0 mass part or less. When the content of the silane coupling agent (B) having a mercapto group is in the above range, the migration prevention effect is more excellent.

  The lower limit of the number of moles of mercapto groups (mercapto group amount) in the silane coupling agent (B) per 100 g of (meth) acrylic acid ester polymer (A) is preferably 0.01 mmol or more, particularly 0. It is preferably 1 mmol or more, and more preferably 0.2 mmol or more. The upper limit of the number of moles is preferably 30 mmol or less, particularly preferably 5 mmol or less, and more preferably 1.5 mmol or less. When the number of moles of the mercapto group of the silane coupling agent (B) relative to the (meth) acrylic acid ester polymer (A) is in the above range, the migration prevention effect can be further improved.

(3) Crosslinking agent (C)
The adhesive composition P preferably contains a crosslinking agent (C). The pressure-sensitive adhesive composition P contains a cross-linking agent (C), thereby cross-linking the (meth) acrylate polymer (A) to form a three-dimensional network structure and improving the cohesive strength of the resulting pressure-sensitive adhesive. The step following property under high temperature and high humidity conditions can be improved.

  As a crosslinking agent (C), what is necessary is just to react with the reactive group which (meth) acrylic acid ester polymer (A) has, for example, an isocyanate type crosslinking agent, an epoxy type crosslinking agent, an amine type crosslinking agent, Melamine-based crosslinking agents, aziridine-based crosslinking agents, hydrazine-based crosslinking agents, aldehyde-based crosslinking agents, oxazoline-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, ammonium salt-based crosslinking agents, etc. Can be mentioned. When the (meth) acrylic acid ester 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 excellent in reactivity with the hydroxyl group. In addition, a crosslinking agent (C) can be used individually by 1 type or in combination of 2 or more types.

  The isocyanate-based crosslinking agent contains at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate, and the like. , And their biuret bodies, isocyanurate bodies, and adduct bodies that are a reaction product with low molecular active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil. Among these, trimethylolpropane-modified aromatic polyisocyanate, particularly trimethylolpropane-modified tolylene diisocyanate is preferable from the viewpoint of reactivity with hydroxyl groups.

  The content of the crosslinking agent (C) in the adhesive composition P is preferably 0.001 part by mass or more as a lower limit with respect to 100 parts by mass of the (meth) acrylic acid ester polymer (A), In particular, it is preferably 0.01 parts by mass or more, and more preferably 0.02 parts by mass or more. Moreover, it is preferable that it is 10 mass parts or less as an upper limit, It is especially preferable that it is 5 mass parts or less, Furthermore, it is preferable that it is 1 mass part or less.

  When the content of the cross-linking agent (C) is in the above range, the cohesive strength of the obtained pressure-sensitive adhesive becomes preferable, and the step following property of the pressure-sensitive adhesive under high temperature and high humidity conditions is improved.

(4) Various additives For the adhesive composition P, if desired, various additives usually used for acrylic pressure-sensitive adhesives such as antistatic agents, tackifiers, antioxidants, ultraviolet absorbers, and light stabilizers. An agent, a softening agent, a filler, a refractive index adjusting agent and the like can be added. In addition to the above-described silane coupling agent (B) having a mercapto group, other silane coupling agents may be added together. However, it is preferable not to add a rust inhibitor, particularly a benzotriazole-based rust inhibitor, because it has an effect of inhibiting the crosslinking of the adhesive composition P.

  Moreover, the adhesive composition P may contain an active energy ray-curable component such as a polyfunctional acrylate monomer having a molecular weight of less than 1000, if desired. When the adhesive composition P contains an active energy ray-curable component, the adhesive layer is pasted on the target member, and then the adhesive layer is irradiated with active energy rays to cure the adhesive layer, thereby achieving durability. A pressure-sensitive adhesive layer having excellent properties can be obtained.

  The pressure-sensitive adhesive composition P represents a mixture of various components that remain in the pressure-sensitive adhesive layer or in a reacted state, and is a component that is removed in a drying step or the like, for example, polymerization described later. Solvents and dilution solvents are not included in the adhesive composition P.

(5) Manufacture of adhesive composition The adhesive composition P manufactured the (meth) acrylic acid ester polymer (A), obtained (meth) acrylic acid ester polymer (A), and a mercapto group. While mixing with the silane coupling agent (B) which has, it can manufacture by adding a crosslinking agent (C) and an additive as needed.

  The (meth) acrylic acid ester polymer (A) can be produced by polymerizing a mixture of monomer units constituting the polymer by an ordinary radical polymerization method. The polymerization of the (meth) acrylic acid ester polymer (A) can be performed by a solution polymerization method or the like using a polymerization initiator as desired. Examples of the polymerization solvent include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone, and the like. Two or more kinds may be used in combination.

  Examples of the polymerization initiator include azo compounds and organic peroxides, and two or more kinds may be used in combination. Examples of the azo compound include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), 1,1′-azobis (cyclohexane 1-carbonitrile), 2 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), 2,2′-azobis [2- (2-imidazolin-2-yl) Propane] and the like.

  Examples of organic peroxides include benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, and di (2-ethoxyethyl) peroxy. Examples include dicarbonate, t-butyl peroxyneodecanoate, t-butyl peroxybivalate, (3,5,5-trimethylhexanoyl) peroxide, dipropionyl peroxide, diacetyl peroxide and the like.

  In addition, in the said superposition | polymerization process, the weight average molecular weight of the polymer obtained can be adjusted by mix | blending chain transfer agents, such as 2-mercaptoethanol.

  When the (meth) acrylic acid ester polymer (A) is obtained, the solution of the (meth) acrylic acid ester polymer (A) is added with a silane coupling agent (B) having a mercapto group and, if desired, a crosslinking agent ( C), an additive and a diluting solvent are added and mixed thoroughly to obtain an adhesive composition P (coating solution) diluted with the solvent.

  Examples of the dilution solvent include aliphatic hydrocarbons such as hexane, heptane, and cyclohexane, aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as methylene chloride and ethylene chloride, methanol, ethanol, propanol, butanol, Alcohols such as 1-methoxy-2-propanol, ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone, and cyclohexanone, esters such as ethyl acetate and butyl acetate, and cellosolve solvents such as ethyl cellosolve are used.

  The concentration / viscosity of the coating solution thus prepared is not particularly limited as long as it can be coated, and can be appropriately selected depending on the situation. For example, it dilutes so that the density | concentration of the adhesive composition P may be 10-40 mass%. In addition, when obtaining a coating solution, addition of a dilution solvent etc. is not a necessary condition, and if a viscosity etc. which can be coated with the adhesive composition P are not necessary, a dilution solvent does not need to be added. In this case, the adhesive composition P becomes a coating solution using the polymerization solvent of the (meth) acrylic acid ester polymer (A) as a dilution solvent.

(6) Manufacture of adhesive The adhesive is obtained by heat-processing the adhesive composition P mentioned above. This heat treatment can also serve as a drying treatment when the diluting solvent of the adhesive composition P is volatilized.

  When performing heat processing, it is preferable that heating temperature is 50-150 degreeC, and it is especially preferable that it is 70-120 degreeC. The heating time is preferably 30 seconds to 10 minutes, particularly preferably 50 seconds to 2 minutes. After the heat treatment, if necessary, a curing period of about 1 to 2 weeks may be provided at room temperature (for example, 23 ° C., 50% RH). When the curing period is necessary, after the curing period has elapsed, when the curing period is unnecessary, the pressure-sensitive adhesive layer is formed after the heat treatment.

  The lower limit of the gel fraction of the pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition P is preferably 30% or more, particularly preferably 40% or more, and further preferably 50% or more. When the lower limit of the gel fraction of the pressure-sensitive adhesive is not less than the above, the cohesive force of the pressure-sensitive adhesive is increased, and the step following property under high temperature and high humidity conditions is excellent. The upper limit of the gel fraction is preferably 90% or less, particularly preferably 85% or less, and more preferably 80% or less. When the upper limit value of the gel fraction of the pressure-sensitive adhesive is not more than the above, the pressure-sensitive adhesive does not become too hard, and the step following property at the time of sticking becomes excellent. Here, the measuring method of the gel fraction of an adhesive is as showing to the test example mentioned later.

  The pressure-sensitive adhesive according to the present embodiment contains a silane coupling agent having a mercapto group as a migration inhibitor, so that, for example, a metal electrode made of copper, silver or the like, a transparent conductive material made of tin-doped indium oxide (ITO) or the like. Even if affixed to a target member such as a film, a metal nanowire film, or a wire grid polarizing film, migration in the target member can be effectively suppressed. In particular, even when the target member is a metal electrode of a touch panel that uses copper, silver, or the like, which has a higher ionization tendency than a metal oxide such as ITO, it is possible to prevent touch panel drive failure due to electrode disconnection or short circuit. .

[Adhesive sheet]
As shown in FIG. 1, the pressure-sensitive adhesive sheet 1 according to this embodiment includes two release sheets 12a and 12b and the two release sheets 12a so as to be in contact with the release surfaces of the two release sheets 12a and 12b. , 12b and an adhesive layer 11 sandwiched between the two layers. However, the release sheets 12a and 12b in the pressure-sensitive adhesive sheet 1 are not essential components, and are peeled and removed when the pressure-sensitive adhesive sheet 1 is used. In addition, the release surface of the release sheet in this specification refers to a surface having peelability in the release sheet, and includes both a surface that has been subjected to a release treatment and a surface that exhibits peelability without being subjected to a release treatment. .

(1) Adhesive layer The adhesive layer 11 is comprised from the adhesive mentioned above. The lower limit value of the thickness of the pressure-sensitive adhesive layer 11 (value measured according to JIS K7130) is preferably 10 μm or more, particularly preferably 25 μm or more, and more preferably 50 μm or more. When the lower limit value of the thickness of the pressure-sensitive adhesive layer 11 is not less than the above, excellent adhesive force is sufficiently exhibited. Further, the upper limit of the thickness of the pressure-sensitive adhesive layer 11 is preferably 300 μm or less, particularly preferably 250 μm or less, and further preferably 100 μm or less. When the upper limit value of the thickness of the pressure-sensitive adhesive layer 11 is not more than the above, workability is improved. The pressure-sensitive adhesive layer 11 may be formed as a single layer or may be formed by laminating a plurality of layers.

(2) Release sheet The release sheets 12a and 12b are not particularly limited, and known plastic films 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, polyethylene naphthalate film, polybutylene terephthalate film, polyurethane film, ethylene acetate A vinyl film, an ionomer resin film, an ethylene / (meth) acrylic acid copolymer film, an ethylene / (meth) acrylic acid ester copolymer film, a polystyrene film, a polycarbonate film, a polyimide film, a fluororesin film, or the like is used. These crosslinked films are also used. Furthermore, these laminated films may be sufficient.

  It is preferable that the peeling surface (especially the surface in contact with the pressure-sensitive adhesive layer 11) of the release sheets 12a and 12b is subjected to a peeling treatment. Examples of the release agent used for the release treatment include alkyd, silicone, fluorine, unsaturated polyester, polyolefin, and wax release agents. Of the release sheets 12a and 12b, one release sheet is preferably a heavy release release sheet having a high release force, and the other release sheet is preferably a light release release sheet having a low release force.

  Although there is no restriction | limiting in particular about the thickness of release sheet 12a, 12b, Usually, it is about 20-150 micrometers.

(3) Manufacture of pressure-sensitive adhesive sheet As a manufacturing example of pressure-sensitive adhesive sheet 1, a coating liquid of the above-mentioned pressure-sensitive adhesive composition P is applied to the release surface of one release sheet 12a (or 12b), and heat treatment is performed to perform pressure-sensitive adhesive. After cross-linking the composition P and forming a coating layer, the release surface of the other release sheet 12b (or 12a) is overlaid on the coating layer. When a curing period is required, a curing period is set, and when the curing period is unnecessary, the coating layer becomes the pressure-sensitive adhesive layer 11 as it is. Thereby, the said adhesive sheet 1 is obtained. The conditions for the heat treatment and curing are as described above.

  As another production example of the pressure-sensitive adhesive sheet 1, a coating liquid of the above-mentioned pressure-sensitive adhesive composition P is applied to the release surface of one release sheet 12 a, a heat treatment is performed to cross-link the pressure-sensitive adhesive composition P, and a coating layer To obtain a release sheet 12a with a coating layer. Moreover, the coating liquid of the said adhesive composition P is apply | coated to the peeling surface of the other peeling sheet 12b, heat processing is performed, the adhesive composition P is bridge | crosslinked, an application layer is formed, and an application layer is attached. A release sheet 12b is obtained. And the peeling sheet 12a with an application layer and the peeling sheet 12b with an application layer are bonded together so that both application layers may mutually contact. When the curing period is necessary, the curing period is set, and when the curing period is unnecessary, the above-mentioned laminated application layer becomes the pressure-sensitive adhesive layer 11 as it is. Thereby, the said adhesive sheet 1 is obtained. According to this production example, even when the pressure-sensitive adhesive layer 11 is thick, it can be stably produced.

  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, or the like can be used as a method for applying the coating solution of the adhesive composition P.

(4) Adhesive strength The lower limit of the adhesive strength of the pressure-sensitive adhesive sheet 1 according to this embodiment to soda lime glass is preferably 5 N / 25 mm or more, particularly preferably 8 N / 25 mm or more, and more preferably 10 N / It is preferable that it is 25 mm or more. When the lower limit value of the adhesive strength of the pressure-sensitive adhesive sheet 1 is not less than the above value, the step following property under high temperature and high humidity conditions is excellent. On the other hand, the upper limit value of the adhesive force is not particularly limited, but is preferably 50 N / 25 mm or less, particularly 30 N in consideration of ease of peeling of the release sheets 12a and 12b from the adhesive layer 11 during use. / 25 mm or less is preferable. Furthermore, if reworkability is also taken into consideration, it is preferably 26 N / 25 mm or less. In that case, even if a bonding mistake occurs, the reuse of the member is facilitated.

  Here, the adhesive force in the present specification basically means an adhesive force measured by a 180-degree peeling method according to JIS Z0237: 2009. The measurement sample is 25 mm wide and 100 mm long. Affixed to the adherend, pressurized at 0.5 MPa, 50 ° C. for 20 minutes, left under normal pressure, 23 ° C., 50% RH for 24 hours, and then measured at a peeling rate of 300 mm / min. Shall.

(5) Use of pressure-sensitive adhesive sheet By using the pressure-sensitive adhesive sheet 1, for example, the capacitive touch panel 2 shown in FIG. 2 can be manufactured. The touch panel 2 includes a display module 3, a first film sensor 5 a laminated thereon via an adhesive layer 4, and a second film sensor 5 b laminated thereon via an adhesive layer 11. And the cover material 6 laminated | stacked through the adhesive layer 11 on it is comprised.

  The pressure-sensitive adhesive layer 11 in the touch panel 2 is the pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1.

  Examples of the display module 3 include a liquid crystal (LCD) module, a light emitting diode (LED) module, an organic electroluminescence (organic EL) module, and electronic paper.

  The pressure-sensitive adhesive layer 4 may be formed by the pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1 or may be formed by another pressure-sensitive adhesive or pressure-sensitive adhesive sheet. In the latter case, the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 4 includes an acrylic pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, a polyester-based pressure-sensitive adhesive, and a polyvinyl ether-based pressure-sensitive adhesive. However, among them, an acrylic pressure-sensitive adhesive is preferable.

  The first film sensor 5 a and the second film sensor 5 b in the present embodiment each include a base film 51 and an electrode 52 formed on the base film 51. Although it does not specifically limit as the base film 51, For example, a polyethylene terephthalate film, an acrylic film, a polycarbonate film etc. are used.

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

  One of the electrode 52 of the first film sensor 5a and the electrode 52 of the second film sensor 5b normally constitutes a circuit pattern in the X-axis direction, and the other constitutes a circuit pattern in the Y-axis direction.

  The electrode 52 of the second film sensor 5b in the present embodiment is located above the second film sensor 5b in FIG. On the other hand, the electrode 52 of the first film sensor 5a is located on the upper side of the first film sensor 5a in FIG. 2, but is not limited to this, and the lower side of the first film sensor 5a. May be located.

  The cover material 6 is mainly composed of a glass plate or a plastic plate. The glass plate is not particularly limited. For example, chemically strengthened glass, alkali-free glass, quartz glass, soda lime glass, barium / strontium-containing glass, aluminosilicate glass, lead glass, borosilicate glass, barium borosilicate glass. Etc. The plastic plate is not particularly limited, and examples thereof include an acrylic plate made of polymethyl methacrylate and the like, and a polycarbonate plate.

  In addition, a functional layer such as a hard coat layer, an antireflection layer, or an antiglare layer may be provided on one side or both sides of the glass plate or plastic plate, or a hard coat film, an antireflection film, or an antiglare film. Such optical members may be laminated.

  In the present embodiment, the cover material 6 has a step on the surface on the pressure-sensitive adhesive layer 11 side, and specifically has a step due to the presence or absence of the printing layer 7. The print layer 7 is generally formed in a frame shape on the pressure-sensitive adhesive layer 11 side of the cover material 6.

  The material which comprises the printing layer 7 is not specifically limited, The well-known material for printing is used. The lower limit of the thickness of the printing layer 7, that is, the height of the step, is preferably 3 μm or more, more preferably 5 μm or more, and particularly preferably 7 μm or more. The upper limit value is preferably 50 μm or less, more preferably 25 μm or less, and particularly preferably 15 μm or less.

An example of the manufacturing method of the touch panel 2 will be described below.
As the pressure-sensitive adhesive sheet 1, a first pressure-sensitive adhesive sheet 1 and a second pressure-sensitive adhesive sheet 1 are prepared. One release sheet 12a is peeled from the first pressure-sensitive adhesive sheet 1, and the exposed pressure-sensitive adhesive layer 11 (first pressure-sensitive adhesive layer 11) is in contact with the electrode 52 of the second film sensor 5b. The film sensor 5b is pasted. Also, one release sheet 12a is peeled from the second pressure-sensitive adhesive sheet 1, and the exposed pressure-sensitive adhesive layer 11 (second pressure-sensitive adhesive layer) is in contact with the electrode 52 of the first film sensor 5a. 1 film sensor 5a.

  Then, the other release sheet 12b in the second adhesive sheet is peeled off and the exposed second adhesive layer 11 is the side on which the first adhesive layer 11 in the second film sensor 5b is laminated. Both are bonded so as to be in contact with the opposite surface (exposed surface of the base film 51 of the second film sensor 5b). Thereby, the laminated body by which the peeling sheet 12b, the 1st adhesive layer 11, the 2nd film sensor 5b, the 2nd adhesive layer 11, and the 1st film sensor 5a are laminated | stacked in order is obtained.

  Next, the pressure-sensitive adhesive layer 4 provided on the release sheet is bonded to the surface of the laminate on the first film sensor 5a side (exposed surface of the base film 51 of the first film sensor 5a). Subsequently, the release sheet 12b is peeled from the laminate, and the cover material 6 is attached to the exposed first pressure-sensitive adhesive layer 11 so that the printed layer 7 side of the cover material 6 is in contact with the pressure-sensitive adhesive layer 11. Paste. Accordingly, the cover material 6, the first pressure-sensitive adhesive layer 11, the second film sensor 5b, the second pressure-sensitive adhesive layer 11, the first film sensor 5a, the pressure-sensitive adhesive layer 4, and the release sheet are sequentially laminated. A construct is obtained.

  Finally, the release sheet is peeled from the structure, and the structure is bonded to the display module 3 so that the exposed adhesive layer 4 is in contact with the display module 3. Thereby, the touch panel 2 shown in FIG. 2 is manufactured.

  Even when the touch panel 2 is placed under high-temperature and high-humidity conditions and a voltage is applied to the electrode 52 in that state, the pressure-sensitive adhesive layer 11 in contact with the electrode 52 is used as the migration inhibitor (mercapto) according to the present embodiment. By containing a component derived from a silane coupling agent having a group, migration of the electrode 52 is effectively suppressed. Thereby, the drive failure of the touch panel 2 resulting from the disconnection or short circuit of the electrode 52 is prevented.

  The embodiment described above is described for facilitating understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

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

  EXAMPLES Hereinafter, although an Example etc. demonstrate this invention further more concretely, the scope of the present invention is not limited to these Examples etc.

[Example 1]
1. Preparation of (meth) acrylic acid ester 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 are copolymerized to produce a (meth) acrylic acid ester polymer. (A) was prepared. When the molecular weight of this (meth) acrylic acid ester polymer (A) was measured by the method described later, it was a weight average molecular weight (Mw) of 600,000.

2. Preparation of Adhesive Composition As (meth) acrylic acid ester polymer (A) 100 parts by mass (in terms of solid content; the same applies hereinafter) obtained in Step 1 above, and a silane coupling agent (B) having a mercapto group Co-condensation product of 3-mercaptopropyltrimethoxysilane and methyltriethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name “X-41-1810”, oligomer type, mercapto group equivalent: 450 g / mol) 0.05 mass Part and 0.23 parts by mass of trimethylolpropane-modified tolylene diisocyanate (product name “Coronate L”, manufactured by Nippon Polyurethane Co., Ltd.) as a crosslinking agent (C), sufficiently stirred and diluted with methyl ethyl ketone Thus, a coating solution of the adhesive composition having a solid content concentration of 38% by mass was obtained.

Here, Table 1 shows each formulation (solid content converted value) of the adhesive composition when the (meth) acrylic acid ester polymer (A) is 100 parts by mass (solid content converted value). Details of the abbreviations and the like described in Table 1 are as follows.
[(Meth) acrylic acid ester polymer (A)]
2EHA: 2-ethylhexyl acrylate MMA: methyl methacrylate HEA: 2-hydroxyethyl acrylate
[Silane coupling agent having mercapto group (B)]
X-41-1810: Co-condensation product of 3-mercaptopropyltrimethoxysilane and methyltriethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name “X-41-1810”, oligomer type, mercapto group equivalent: 450 g / mol) )
KBM-803: 3-mercaptopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name “KBM-803”, low molecular type, mercapto group equivalent: 196.4 g / mol)
[Other silane coupling agents]
KBM-403: 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Silicone, trade name “KBM-403”, low molecular weight type)
KBE-9007: 3-isocyanatopropyltriethoxysilane (manufactured by Shin-Etsu Silicone, trade name “KBE-9007”, low molecular weight type)

3. Manufacture of an adhesive sheet The application | coating solution of the adhesive composition obtained at the said process 2 is a heavy peeling type release sheet (the product name "SP-PET382150 made from a Lintec company) which peeled one side of the polyethylene terephthalate film with the silicone type release agent. ”, Thickness: 38 μm) was applied with a knife coater and then heat-treated at 90 ° C. for 1 minute to form a coating layer (thickness: 25 μm). Similarly, the light release release sheet (product name “SP-PET 382120”, manufactured by Lintec Co., Ltd.) obtained by removing one surface of the polyethylene terephthalate film with a silicone-based release agent from the coating solution of the adhesive composition obtained in Step 2 above. ) Was applied with a knife coater, followed by heat treatment at 90 ° C. for 1 minute to form a coating layer (thickness: 25 μm).

  Subsequently, the heavy release type release sheet with the coating layer obtained above and the light release type release sheet with the coating layer obtained above were bonded so that both coating layers were in contact with each other. By curing for 7 days under the condition of 50% RH, a pressure-sensitive adhesive sheet having a structure of heavy release type release sheet / pressure-sensitive adhesive layer (thickness: 50 μm) / light release type release sheet was produced.

[Examples 2 to 10, Comparative Examples 1 to 10]
Except changing the kind and ratio of the silane coupling agent (the silane coupling agent (B) and other silane coupling agent having a mercapto group and other silane coupling agents) and the ratio of the crosslinking agent (C) as shown in Table 1, Examples A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1. In Comparative Examples 7 to 10, N, N-bis (2-ethylhexyl)-(4 or 5) -methyl-1H-benzotriazole-1-methylamine (manufactured by BASF, trade name “ IRGMET 39 ") was blended into the adhesive composition in the proportions shown in Table 1.

Here, the above-mentioned weight average molecular weight (Mw) is a polystyrene-reduced weight average molecular weight measured under the following conditions (GPC measurement) using gel permeation chromatography (GPC).
<Measurement conditions>
GPC measurement device: manufactured by Tosoh Corporation, HLC-8020
GPC column (passed in the following order): TSK guard column HXL-H manufactured by Tosoh Corporation
TSK gel GMHXL (× 2)
TSK gel G2000HXL
・ Measurement solvent: Tetrahydrofuran ・ Measurement temperature: 40 ° C.

[Test Example 1] (Measurement of gel fraction)
The pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples were cut into a size of 80 mm × 80 mm, the pressure-sensitive adhesive layer was wrapped in a polyester mesh (mesh size 200), the mass was weighed with a precision balance, and the mesh By subtracting the single mass, the mass of the adhesive alone was calculated. The mass at this time is M1.

  Next, the pressure-sensitive adhesive wrapped in the polyester mesh was immersed in ethyl acetate at room temperature (23 ° C.) for 24 hours. Thereafter, the pressure-sensitive adhesive was taken out, air-dried for 24 hours in an environment of 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, the mass was weighed with a precision balance, and the mass of the pressure sensitive adhesive alone was calculated by subtracting the mass of the mesh alone. The mass at this time is M2. The gel fraction (%) is represented by (M2 / M1) × 100. The results are shown in Table 2.

[Test Example 2] (Measurement of adhesive strength)
The light release type release sheet was peeled from the pressure sensitive adhesive sheets obtained in Examples and Comparative Examples, and the exposed pressure sensitive adhesive layer was replaced with a polyethylene terephthalate (PET) film having an easy-adhesive layer (product name “PET A4300” manufactured by Toyobo Co., Ltd.). , Thickness: 100 μm) to obtain a laminate of heavy release type 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 release type 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 placed in an autoclave manufactured by Kurihara Seisakusho. And pressurized at 0.5 MPa and 50 ° C. for 20 minutes. Then, after being allowed to stand for 24 hours under the conditions of 23 ° C. and 50% RH, using a tensile tester (Orientec, Tensilon), the adhesive strength (N / 25 mm). Conditions other than those described here were measured according to JIS Z 0237: 2009. The results are shown in Table 2.

[Test Example 3] (Evaluation of migration prevention effect)
(1) Fabrication of a wiring board Copper of a copper clad laminate (product name “Nikaflex” manufactured by Nikkan Kogyo Co., Ltd.) obtained by laminating a copper foil (thickness: 18 μm) and a polyethylene terephthalate film (thickness: 50 μm) An etching resist pattern was printed on the foil surface by a screen printing method. Thereafter, unnecessary copper foil was removed by etching to form a comb-shaped electrode. The line width of each electrode was 300 μm, and the gap between the electrodes was 50 μm.

(2) Evaluation of migration prevention effect The light release type release sheet was peeled from the pressure sensitive adhesive sheets obtained in Examples and Comparative Examples, and the exposed pressure sensitive adhesive layer was replaced with a polyethylene terephthalate (PET) film (Toyobo Co., Ltd.). The product was bonded to an easy-adhesion layer having a product name “PET A4300” (thickness: 100 μm) to obtain a laminate of a heavy release type release sheet / adhesive layer / PET film. Next, the heavy release type release sheet was peeled from the laminate, and the exposed pressure-sensitive adhesive layer was pasted on the comb electrode, which was used as a sample.

The sample was allowed to stand under wet heat conditions of 85 ° C. and 85% RH, and a voltage of 5 V was applied between the electrodes in this state to perform a migration test. After 8 hours, 24 hours, and 48 hours from the start of the test, the comb electrode was observed with an optical microscope (magnification: 10 times), and the migration prevention effect was evaluated based on the evaluation criteria shown below. The results are shown in Table 2.
A: The dissolution of the electrode (positive electrode) and the formation of dendrite in the electrode (negative electrode) are not observed at all.
◯: Dissolution is observed only at the end of the electrode (positive electrode), and dendrite formation is not observed at the electrode (negative electrode).
X: Dissolution of the electrode (positive electrode) and formation of dendrite in the electrode (negative electrode) are observed.
A reference image of the evaluation criteria is shown in FIG.

  As can be seen from Table 2, the pressure-sensitive adhesive sheets obtained in the examples were able to effectively prevent and suppress migration, and were excellent in the migration prevention effect.

  The migration inhibitor, the pressure-sensitive adhesive, and the pressure-sensitive adhesive sheet according to the present invention can be suitably used for a capacitive touch panel using a copper electrode or a silver electrode, for example.

DESCRIPTION OF SYMBOLS 1 ... Adhesive sheet 11 ... Adhesive layer 12a, 12b ... Release sheet 2 ... Touch panel 3 ... Display body module 4 ... Adhesive layer 5a ... 1st film sensor 5b ... 2nd film sensor 51 ... Base film 52 ... Electrode 6 ... Cover material 7 ... Printing layer

Claims (10)

  A migration inhibitor comprising a silane coupling agent having a mercapto group.   The migration inhibitor according to claim 1, wherein the silane coupling agent is a mercapto group-containing oligomer type silane coupling agent.   The migration inhibitor according to claim 1 or 2, wherein the mercapto group equivalent of the organosilicon compound constituting the silane coupling agent is 100 g / mol or more and 1000 g / mol or less.   The adhesive obtained from the adhesive composition containing the migration inhibitor as described in any one of Claims 1-3. The adhesive composition is
(Meth) acrylic acid ester polymer (A),
The pressure-sensitive adhesive according to claim 4, comprising a silane coupling agent (B) having a mercapto group as the migration inhibitor.   The said (meth) acrylic acid ester polymer (A) contains 3 mass% or more and 35 mass% or less of hydroxyl-containing monomers as a monomer unit which comprises the said polymer. Adhesive.   The pressure-sensitive adhesive composition according to any one of claims 5 to 6, wherein the pressure-sensitive adhesive composition further contains a crosslinking agent (C).   Content of the said silane coupling agent (B) which has the said mercapto group in the said adhesive composition is 0.01 mass part or more with respect to 100 mass parts of said (meth) acrylic acid ester polymers (A), It is 5 mass parts or less, The adhesive as described in any one of Claims 5-7 characterized by the above-mentioned. Two release sheets,
An adhesive layer sandwiched between the release sheets so as to be in contact with the release surfaces of the two release sheets;
The said adhesive layer consists of an adhesive as described in any one of Claims 4-8, The adhesive sheet characterized by the above-mentioned.   The pressure-sensitive adhesive sheet according to claim 9, wherein the pressure-sensitive adhesive layer is disposed so as to be in contact with an electrode on a touch panel.