KR102308653B1 - Adhesive comoposition and display device - Google Patents

Abstract

일반식 (1)The present invention relates to a (meth)acrylic copolymer comprising a structural unit derived from a monomer having a hydroxyl group, a polyvalent isocyanate compound having a partial structure and an isocyanurate ring structure derived from an aromatic diisocyanate compound, the following general formula (1) Provided are an N-substituted imidazole compound represented by , and an ionic compound, wherein the cation of the ionic compound is a metal cation or an organic cation having a total carbon number of a hydrocarbon group of 7 or more, and a display device using the same.
In formula, R<^1> represents an alkyl group, an aryl group, or an aralkyl group. In the formula, R ² , R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group.
R ³ and R ⁴ may be linked to each other to form a ring.

General formula (1)

Description

Adhesive composition and display device {Adhesive comoposition and display device}

The present invention relates to a pressure-sensitive adhesive composition and a display device.

As a display device which displays an image, such as a liquid crystal display device and an organic electroluminescent display device, the apparatus of various display systems is widespread. Among these, liquid crystal display devices generally have a structure in which a liquid crystal cell in which a liquid crystal component oriented in a predetermined direction is interposed between two supporting substrates such as glass and an optical film such as a polarizing plate, retardation film, and brightness enhancement film are bonded. . When laminating|stacking optical films or adhering an optical film to a liquid crystal cell, a transparent acrylic adhesive is used in many cases.

In addition, a touch panel may be mounted as an input device in a liquid crystal display device. In recent years, what has a touch panel inside a liquid crystal display device is also increasing. An acrylic adhesive is also used for adhesion|attachment of the member (polarizing plate, etc.) which comprises a touch panel and a liquid crystal display device in many cases. Since the transparent electrode film constituting the touch panel is corroded by the acidic component contained in the pressure-sensitive adhesive, a pressure-sensitive adhesive containing no acidic component is required when the polarizing plate and the touch panel are adhered.

However, the acrylic pressure-sensitive adhesive requires a long curing time of about 1 week at room temperature in order to obtain the required adhesive performance, and there have been problems in that the productivity is lowered or the inventory quantity is increased due to the long curing time. International Publication No. 2011/062127 describes a method of shortening the curing time of an adhesive by combining a tolylene diisocyanate-based compound having an isocyanurate structure as a crosslinking agent in a resin having a hydroxyl group and a carboxyl group. A method is disclosed.

In addition, since the optical film is made of a highly insulating plastic material, it is easy to generate static electricity due to friction between the films. When the generated static electricity is charged on the film, it may have adverse effects such as adsorbing dust or dirt or causing malfunctions in electronic devices. Japanese Patent Application Laid-Open No. 2004-114665 discloses imparting antistatic properties to a pressure-sensitive adhesive applied to a film as a means for preventing the film from being charged. A pressure-sensitive adhesive composition comprising an antistatic agent as a pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive layer is disclosed.

However, in the pressure-sensitive adhesive composition comprising a tolylene diisocyanate-based compound having a tolylene diisocyanate-based compound having an isocyanurate structure described in International Publication No. 2011/062127, Japanese Patent Application Laid-Open No. 2004-114665, and Japan When the antistatic agent described in Unexamined-Japanese-Patent No. 2009-155585 was mix|blended, the adhesive composition became white turbidity, and it was difficult to form the adhesive layer with high transparency in some cases.

This invention was made in view of said viewpoint, and makes it a subject to achieve the following objects. That is, an object of the present invention is to provide a pressure-sensitive adhesive composition having high transparency and antistatic properties and a short curing time, and a display device in which malfunction due to charging is prevented.

The present invention provides a pressure-sensitive adhesive composition comprising a polyisocyanate compound having a partial structure and an isocyanurate ring structure derived from an aromatic diisocyanate compound, and an N-imidazole compound represented by the general formula (1). In this case, as an antistatic agent, by using an ionic compound in which the cation is a metal cation or an organic cation in which the total carbon number of the hydrocarbon group is 7 or more, the curing time can be shortened and an antistatic effect can be imparted while maintaining transparency. It has been completed based on the knowledge that it is possible and related knowledge.

Specific means for solving the above problems are as follows.

<1> A (meth)acrylic copolymer containing a structural unit derived from a monomer having a hydroxyl group, and a polyvalent isocyanate compound having a partial structure and an isocyanurate ring structure derived from an aromatic diisocyanate compound, the following general formula (1) ), including an N-substituted imidazole compound, and an ionic compound, wherein the cation of the ionic compound is a metal cation or an organic cation having 7 or more carbon atoms in the hydrocarbon group.

[Formula 1]

일반식 (1)

General formula (1)

In formula, R<^1> represents an alkyl group, an aryl group, or an aralkyl group. In the formula, R ² , R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group.

R ³ and R ⁴ may be connected to each other to form a ring.

<2> The pressure-sensitive adhesive composition according to <1>, wherein the content of the ionic compound is 0.1 parts by mass or more with respect to 100 parts by mass of the (meth)acrylic copolymer.

<3> The pressure-sensitive adhesive composition according to <1> or <2>, wherein the content of the N-substituted imidazole compound is 0.01 parts by mass to 0.6 parts by mass with respect to 100 parts by mass of the (meth)acrylic copolymer.

<4> The pressure-sensitive adhesive composition according to any one of <1> to <3>, wherein the content of the polyvalent isocyanate compound is 0.01 parts by mass to 0.5 parts by mass with respect to 100 parts by mass of the (meth)acrylic copolymer.

<5> The pressure-sensitive adhesive composition according to any one of <1> to <4>, wherein the (meth)acrylic copolymer has 0.3% by mass to 12% by mass of a structural unit derived from a monomer having a hydroxyl group.

The display device which has a <6> touchscreen and the polarizing plate with an adhesive containing the adhesive layer formed with the adhesive composition in any one of <1>-<5>.

ADVANTAGE OF THE INVENTION According to this invention, it is transparent, has antistatic property, and the adhesive composition with which the curing time was shortened, and the display apparatus by which malfunction by charging is prevented are provided.

In this specification, the numerical range indicated using "-" represents a range including the numerical value described before and after "-" as the minimum value and the maximum value, respectively. In addition, the content of each component in the composition means the total content of the plurality of substances present in the composition unless otherwise specified, when a plurality of substances corresponding to each component exist in the composition.

In addition, (meth)acrylate means at least one of acrylate and methacrylate, and (meth)acrylic means at least one of acryl and methacrylic.

<Adhesive composition>

In the present invention, the pressure-sensitive adhesive composition is a (meth)acrylic copolymer comprising a structural unit derived from a monomer having a hydroxyl group, and a polyvalent isocyanate compound having a partial structure and an isocyanurate ring structure derived from an aromatic diisocyanate compound, and general An N-substituted imidazole compound represented by Formula (1) is included, and the cation of the ionic compound is a metal cation or an organic cation having 7 or more carbon atoms in total in the hydrocarbon group.

In the present invention, the pressure-sensitive adhesive composition may further include other components such as a silane coupling agent and other additives, if necessary.

As a use of an adhesive composition in this invention, the object for a polarizing plate is mentioned, for example, It is used for adhesion of a polarizing plate and a liquid crystal cell, or adhesion of a polarizing plate and a touch panel.

In the present invention, the pressure-sensitive adhesive composition as described above can have antistatic properties while maintaining transparency, and it is also possible to shorten the curing time.

Although the reason the effect of this invention is acquired is not clear, the present inventors estimate as follows.

In the present invention, the pressure-sensitive adhesive composition comprises a polyvalent isocyanate compound having a partial structure and an isocyanurate ring structure derived from an aromatic diisocyanate compound, and an N-substituted imidazole compound represented by the general formula (1), and thus the polyvalent isocyanate compound And since the crosslinking reaction with the (meth)acrylic-type copolymer containing the structural unit derived from the monomer which has a hydroxyl group is accelerated|stimulated, it is considered that the hardening time of an adhesive composition can be shortened.

In addition, by using an ionic compound in which the cation is a metal cation or an organic cation in which the total carbon number of a hydrocarbon group is 7 or more as an antistatic agent in a composition comprising the polyvalent isocyanate compound and the N-substituted imidazole compound, the polyvalent isocyanate compound and ions It is considered that the antistatic effect can be imparted while maintaining transparency because the active compound is difficult to react.

In addition to the above, the content of the structural unit derived from the monomer having a hydroxyl group in the (meth)acrylic copolymer is not more than a predetermined amount, and the pot life of the pressure-sensitive adhesive composition is excellent. In addition, the content of the N-substituted imidazole compound in the pressure-sensitive adhesive composition is not more than a predetermined amount, the useful life of the pressure-sensitive adhesive composition is excellent.

In addition, the (meth)acrylic copolymer has a structural unit derived from a monomer having a hydroxyl group, and the (meth)acrylic copolymer is crosslinked with a polyisocyanate compound having an isocyanurate ring structure to form a pressure-sensitive adhesive layer. It is considered to have excellent balance of viscosity and viscosity.

≪(meth)acrylic copolymer≫

In the present invention, the pressure-sensitive adhesive composition includes a (meth)acrylic copolymer (hereinafter, simply referred to as a “copolymer”) containing at least one structural unit derived from a monomer having a hydroxyl group.

Components other than the structural unit derived from the monomer having a hydroxyl group in the (meth)acrylic copolymer can be selected from structural units derived from other monomers copolymerizable with the monomer having a hydroxyl group.

In the present invention, the (meth)acrylic copolymer preferably contains 50% by mass or more of structural units derived from the (meth)acrylic monomer with respect to the total mass of the copolymer.

The (meth)acrylic monomer as used herein means a generic term for a (meth)acrylic monomer having a hydroxyl group, alkyl (meth)acrylate, (meth)acrylate having a cyclic group, and the like, which will be described later.

(Structural unit derived from a monomer having a hydroxyl group)

In the present invention, the (meth)acrylic copolymer includes at least one structural unit derived from a monomer having a hydroxyl group.

The (meth)acrylic copolymer can crosslink-react with the polyvalent isocyanate compound which has the specific structure mentioned later including the structural unit derived from the monomer which has a hydroxyl group. For this reason, when it is set as an adhesive layer, cohesive force improves, and when it is set as an adhesive layer, durability becomes excellent. In addition, when the pressure-sensitive adhesive composition of the present invention is applied to a polarizing plate of a display device, light leakage can be suppressed.

The monomer having a hydroxyl group constituting the (meth)acrylic copolymer is selected from monomers having at least one hydroxyl group in one molecule. Although the number of hydroxyl groups in particular in one molecule of the monomer which has a hydroxyl group is not restrict|limited, It is preferable that it is one.

As a monomer having a hydroxyl group, for example, (meth) having a hydroxyl group such as hydroxyalkyl (meth)acrylate, (poly)alkylene glycol mono(meth)acrylate, N-hydroxyalkyl (meth)acrylamide, etc. acrylic monomers, hydroxyalkyl vinyl ethers, alcohol derivatives having an ethylenic double bond, and the like. Among these, it is preferable that it is a (meth)acrylic-type monomer which has a hydroxyl group, as for the monomer which has a hydroxyl group, It is more preferable that it is a hydroxyalkyl (meth)acrylate, It is more preferable that it is a hydroxyalkyl acrylate.

In the hydroxyalkyl (meth)acrylate, the alkyl group may be linear or pulverized. As carbon number of an alkyl group, it is preferable that it is 2-8, It is more preferable that it is 2-6, It is still more preferable that it is 2-4. In addition, the substitution position in particular of a hydroxyl group is not restrict|limited.

As the monomer having a hydroxyl group, for example, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth) ) acrylate, 6-hydroxyhexyl (meth) acrylate, 3-methyl-3-hydroxybutyl (meth) acrylate, 1,1-dimethyl-3-hydroxybutyl (meth) acrylate, 1,3 -Dimethyl-3-hydroxybutyl (meth)acrylate, 2,2,4-trimethyl-3-hydroxypentyl (meth)acrylate, 2-ethyl-3-hydroxyhexyl (meth)acrylate, glycerin mono (meth)acrylate, polypropylene glycol mono (meth) acrylate, polyethylene glycol mono (meth) acrylate, poly (ethylene glycol-propylene glycol) mono (meth) acrylate, N-methylol acrylamide, N-hydr hydroxyethyl acrylamide, 2-hydroxyethyl vinyl ether, allyl alcohol, methallyl alcohol, and the like.

The monomer which has a hydroxyl group can be used individually by 1 type, and can also be used in combination of 2 or more type.

The content ratio of the structural unit derived from the monomer having a hydroxyl group in the (meth)acrylic copolymer is 0.3% by mass to 12% by mass relative to the total mass of the (meth)acrylic copolymer from the viewpoint of shortening the curing time and the useful life, and , 0.5 mass % - 8 mass % are more preferable.

If the content rate of the structural unit derived from the monomer which has a hydroxyl group in the (meth)acrylic-type copolymer is 0.3 mass % or more, a crosslinking reaction will advance easily, and hardening time can be shortened more. Moreover, a useful life becomes more favorable that the content rate of the structural unit derived from the monomer which has a hydroxyl group is 12 mass % or less.

The (meth)acrylic copolymer is a structural unit derived from a monomer having a hydroxyl group from the viewpoint of shortening curing time, useful life, and durability in the case of a pressure-sensitive adhesive layer, and is a hydroxyalkyl (meth)acrylate having 2 to 6 carbon atoms in the alkyl group. It is preferable to contain 0.3 mass % to 12 mass % of structural units derived from It is more preferable to do so, and it is still more preferable to include 0.5 mass % to 8 mass % of structural units derived from hydroxyalkyl acrylate having 2 to 4 carbon atoms in the alkyl group moiety.

(Structural units derived from other monomers)

In the present invention, the (meth)acrylic copolymer preferably contains at least one type of structural unit derived from other monomers.

In the present invention, other monomers may be selected from among monomers copolymerizable with the monomer having a hydroxyl group, as long as the scope of the present invention is not exceeded.

Examples of the other monomer include alkyl (meth)acrylate, a monomer having a cyclic group, a monomer having an acidic group, a monomer having a basic group, a vinyl cyanide monomer, and a vinyl ester monomer. Among these, alkyl (meth)acrylate and the monomer which has a cyclic group are preferable, and alkyl (meth)acrylate is more preferable.

Other monomers can be used individually by 1 type, and can also be used in combination of 2 or more type.

-Alkyl (meth)acrylate-

In the present invention, the (meth)acrylic copolymer preferably includes a structural unit derived from an alkyl (meth)acrylate as a structural unit derived from other monomers.

1-20 are preferable from a viewpoint of being easy to adjust the cohesion force and adhesive force of an adhesive composition, as for carbon number of the alkyl group of an alkyl (meth)acrylate, 1-18 are more preferable, and 1-12 are still more preferable. The alkyl group of the alkyl (meth)acrylate may be linear or pulverized.

As the alkyl (meth)acrylate, for example, methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylic Rate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl ( Meth)acrylate, n-dodecyl (meth)acrylate, stearyl (meth)acrylate, etc. are mentioned.

-Monomer having a cyclic group-

In the present invention, the (meth)acrylic copolymer preferably includes a structural unit derived from a monomer having a cyclic group as a structural unit derived from other monomers.

The monomer having a cyclic group has at least one cyclic group in the molecule and is not particularly limited as long as it is a polymerizable compound copolymerizable with a monomer having a hydroxyl group. In the monomer having a cyclic group, examples of the cyclic group include an aromatic hydrocarbon group, an aromatic heterocyclic group, and an aliphatic hydrocarbon group. Among them, an aromatic hydrocarbon group is preferable, and an aromatic hydrocarbon group having 6 to 10 carbon atoms is more preferable.

It is preferable that it is 1-2, and, as for the number of cyclic group containing in the monomer which has a cyclic group, it is more preferable that it is 1.

As a monomer which has a cyclic group, (meth)acrylate which has a cyclic group, (meth)acrylamide which has a cyclic group, a styrene derivative, etc. are mentioned, for example. Among these, the (meth)acrylate which has a cyclic group is preferable, and the (meth)acrylate which has an aromatic hydrocarbon group is more preferable.

The (meth)acrylate having an aromatic hydrocarbon group is preferably a (meth)acrylate in which an aromatic hydrocarbon group is ester-bonded through an alkylene group, an oxyalkylene group or a polyoxyalkylene group, and an aromatic hydrocarbon group is ester-bonded through an oxyalkylene group (meth) ) It is more preferable that it is an acrylate.

As a monomer which has a cyclic group, For example, phenyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxypropyl (meth)acrylate, phenoxydiethylene glycol (meth)acryl rate, ethylene oxide (EO) modified cresol (meth) acrylate, ethylene oxide (EO) modified nonylphenol (meth) acrylate, β-naphthyloxyethyl (meth) acrylate, biphenyl (meth) acrylate, etc. (meth)acrylamide such as (meth)acrylate having an aromatic hydrocarbon group, N-methyl-N-phenyl (meth)acrylamide, styrene, α-methylstyrene, t-butylstyrene, p-chlorostyrene, and chloromethylstyrene and styrene derivatives such as vinyltoluene.

Among these, the monomer having a cyclic group is an aromatic ring group such as phenoxyethyl (meth)acrylate, phenoxypropyl (meth)acrylate, β-naphthyloxyethyl (meth)acrylate, which is ester-bonded through an oxyalkylene group (meth). ) acrylates are preferred.

As other monomers, in addition to the above-mentioned alkyl (meth)acrylate and the monomer having a cyclic group, a monomer having an acidic group such as acrylic acid, methacrylic acid, ω-carboxypolycaprolactone mono(meth)acrylate; monomers having a basic group such as aminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, dimethylaminopropyl (meth)acrylate, and vinylpyridine; vinyl cyanide monomers such as acrylonitrile and methacrylonitrile; Vinyl ester monomers, such as vinyl formate, vinyl acetate, a vinyl propionate, and a vinyl versatate, etc. can also be used.

When the (meth)acrylic copolymer contains a structural unit derived from an alkyl (meth)acrylate, it is preferably included as a main component constituting the (meth)acrylic copolymer, and the content ratio is the (meth)acrylic copolymer. It is preferable that it is 75 mass % or more in the total mass of, It is preferable that it is 80 mass % - 99.7 mass %, It is more preferable that it is 90 mass % - 99.5 mass %. If the content ratio of the structural unit derived from alkyl (meth)acrylate in the (meth)acrylic copolymer is within the above range, the elastic modulus can be adjusted to a suitable range, and durability and tackiness are ensured in the case of an adhesive layer advantageous in

When the (meth)acrylic copolymer contains a structural unit derived from a monomer having a cyclic group, the content is preferably 1% by mass to 10% by mass in the total mass of the (meth)acrylic copolymer, 2% by mass It is more preferable that it is -9 mass %, and it is still more preferable that it is 3 mass % - 7 mass %.

In the present invention, the content ratio of the structural unit derived from the monomer having an acidic group in the structural unit of the (meth)acrylic copolymer is preferably 0.5% by mass or less, and more preferably 0.2% by mass or less, based on the total mass of the (meth)acrylic copolymer. Preferably, it is more preferable that it does not contain substantially.

Substantially not included herein means allowing the presence of structural units derived from monomers having an acidic group that are unavoidably incorporated.

When the content rate of the structural unit derived from the monomer having an acidic group in the (meth)acrylic copolymer is 0.5 mass% or less, the pressure-sensitive adhesive layer derived from the pressure-sensitive adhesive composition of the present invention is in contact with a transparent electrode such as a touch panel, Corrosion of the electrode can be suppressed. For this reason, the adhesive composition of this invention can be used suitably for the polarizing plate for display apparatuses with which the touch panel was mounted.

The following two are mentioned as a preferable aspect of the (meth)acrylic-type copolymer in this invention.

As a 1st aspect, the aspect in which a (meth)acrylic-type copolymer contains the structural unit derived from the (meth)acryl monomer which has a hydroxyl group, and the structural unit derived from an alkyl (meth)acrylate is mentioned.

As a second aspect, the (meth)acrylic copolymer comprises a structural unit derived from a (meth)acrylic monomer having a hydroxyl group, a structural unit derived from an alkyl (meth)acrylate, and a structural unit derived from a monomer having a cyclic group. A sun containing it is mentioned.

«Polymerization method of (meth)acrylic copolymer»

The (meth)acrylic copolymer may be prepared by polymerizing a monomer composition including a monomer having a hydroxyl group and other monomers. The polymerization method in particular of a monomer composition is not restrict|limited, It can select suitably from the polymerization method normally used. As a polymerization method, solution polymerization, emulsion polymerization, suspension polymerization, etc. are mentioned. Among them, solution polymerization, which is relatively easy to manufacture, is preferable.

In solution polymerization, a predetermined organic solvent, a monomer, a polymerization initiator, and, if necessary, a chain transfer agent are added into a polymerization tank, and the reaction is heated for several hours while stirring in a nitrogen atmosphere or under reflux of the organic solvent. It does not restrict|limit especially as said polymerization initiator, For example, an azo-type compound can be used.

In addition, the weight average molecular weight (Mw) and number average molecular weight (Mn) of the (meth)acrylic copolymer can be adjusted to a desired molecular weight by adjusting the reaction temperature, reaction time, amount of solvent, and type or amount of catalyst.

In the present invention, the weight average molecular weight (Mw) of the (meth)acrylic copolymer is not particularly limited, and for example, it can be 800,000 to 1.8 million, preferably 1 million to 1.8 million, and 1.3 million to 1.8 million. more preferably. The weight average molecular weight of a (meth)acrylic-type copolymer is excellent in the said range, and it is excellent in handling property at the time of coating of an adhesive composition, and durability at the time of setting it as an adhesive layer.

In addition, the degree of dispersion (Mw/Mn) of the (meth)acrylic copolymer is not particularly limited, and may be, for example, 2 to 10, preferably 4 to 9, and more preferably 5 to 8. When a dispersion degree is the said range and it sets it as an adhesive layer, it is excellent in durability.

In the present invention, the weight average molecular weight (Mw) and number average molecular weight (Mn) of the (meth)acrylic copolymer are values measured by the following method using gel permeation chromatography (GPC).

(1) A (meth)acrylic copolymer solution is applied on a release sheet (release sheet) and dried at 100°C for 2 minutes to obtain a film-like (meth)acrylic copolymer.

(2) The film-form (meth)acrylic copolymer obtained in the above (1) is dissolved in tetrahydrofuran so as to have a solid content of 0.2 parts by mass.

(3) Measure the weight average molecular weight (Mw) and number average molecular weight (Mn) of the (meth)acrylic copolymer as standard polystyrene conversion values using gel permeation chromatography (GPC) under the following conditions.

<condition>

GPC: HLC-8220 GPC (manufactured by Toso Co., Ltd.)

·Column: 4 TSK-GEL GMHXL used (Toso Co., Ltd. product)

· Mobile phase solvent: tetrahydrofuran

Flow rate: 0.8 ml/min

·Column temperature: 40 ℃

It is preferable that it is 70 mass % or more in the total mass of the adhesive composition, and, as for the content rate of the (meth)acrylic-type copolymer in an adhesive composition, it is more preferable that it is 80 mass % or more.

≪Polyvalent isocyanate compound≫

In the present invention, the pressure-sensitive adhesive composition contains at least one kind of a polyvalent isocyanate compound (hereinafter simply referred to as a "polyvalent isocyanate compound") having a partial structure derived from an aromatic diisocyanate compound and an isocyanurate ring structure.

The polyvalent isocyanate compound acts as a crosslinking agent for the (meth)acrylic copolymer. That is, the pressure-sensitive adhesive composition of the present invention contains a structural unit derived from a monomer having a hydroxyl group in the (meth)acrylic copolymer and a polyvalent isocyanate compound having a specific structure. can be compatible.

The polyvalent isocyanate compound can be used by selecting from compounds having a partial structure derived from an aromatic diisocyanate compound and an isocyanurate ring structure. Especially, it is preferable that the polyhydric isocyanate compound is a polyhydric isocyanate compound in which the isocyanate group formed the isocyanurate ring structure by addition reaction in several aromatic diisocyanate compounds, respectively. In this case, the number of aromatic diisocyanate compounds forming the polyvalent isocyanate compound may be one, or a mixture of two or more.

Further, the aromatic diisocyanate compound may be a compound having two isocyanate groups on the aromatic ring, preferably a compound having two isocyanate groups on the benzene ring, more preferably tolylene diisocyanate, 2,4-tol More preferably, it is at least one of rylene diisocyanate or 2,6-tolylene diisocyanate.

Specifically as the polyvalent isocyanate compound, a compound that is a trimer of an aromatic diisocyanate compound represented by the following general formula (2), a compound that is a pentamer of an aromatic diisocyanate compound represented by the following general formula (3), and an aromatic diisocyanate compound of 7-mer and the like. In addition, the polyvalent isocyanate compound may be a compound having an isocyanurate ring structure formed of an aromatic diisocyanate compound and an alkylene diisocyanate compound, and an isocyanurate ring structure formed of tolylene diisocyanate and hexamethylene diisocyanate. It is also preferable that it is a compound having

A polyvalent isocyanate compound may be used individually by 1 type, and may be used in combination of 2 or more type.

In the general formulas (2) and (3), R ¹¹ to R ²⁵ each independently represent a hydrogen atom or a methyl group. It is preferable that one of R ¹¹ to R ¹³ is a methyl group and the remainder is a hydrogen atom. It is preferable that one of R ¹⁴ to R ¹⁶ is a methyl group and the remainder is a hydrogen atom. It is preferable that one of R ¹⁷ to R ¹⁹ is a methyl group and the remainder is a hydrogen atom. It is preferable that one of R ²⁰ to R ²² is a methyl group and the remainder is a hydrogen atom. It is preferable that one of R ²³ to R ²⁵ is a methyl group and the remainder is a hydrogen atom.

The polyvalent isocyanate compound which has the partial structure and isocyanurate ring structure derived from an aromatic diisocyanate compound can be manufactured by a conventional method, and a commercially available thing may be sufficient. As a commercial item of a polyhydric isocyanate compound, "Death module IL1451CN", "Death module ILBA", "Death module HL", "Smidur FL-2", "Smidur FL-3" manufactured by Sumitomo Bayer Urethane Co., Ltd. are, for example, a commercial item. ' and "SBU Isocyanate 0817", "Colonate 2030" and "Colonate 2037" manufactured by Nippon Polyurethane Industries, Ltd., and "Polurene KC" and "Polurene HR" manufactured by SAPICI.

The content of the polyvalent isocyanate compound in the pressure-sensitive adhesive composition is preferably in the range of 0.01 parts by mass to 0.5 parts by mass, more preferably in the range of 0.05 parts by mass to 0.3 parts by mass, with respect to 100 parts by mass of the (meth)acrylic copolymer, and 0.05 parts by mass It is more preferable that it is in the range of parts - 0.2 mass parts.

When content of a polyvalent isocyanate compound is 0.01 mass part or more, since a crosslinking reaction fully advances and cohesion force becomes high enough, when setting it as an adhesive layer, it is excellent in adhesiveness and durability. In addition, when the content of the polyvalent isocyanate compound is 0.5 parts by mass or less, the polyvalent isocyanate compound and the ionic compound are difficult to react, and white turbidity of the pressure-sensitive adhesive composition can be further suppressed, and the pressure-sensitive adhesive composition has excellent transparency.

In the present invention, the pressure-sensitive adhesive composition may further include other crosslinking agents in addition to the polyvalent isocyanate compound. As another crosslinking agent, an isocyanate type crosslinking agent, an epoxy type crosslinking agent, etc. are mentioned other than the polyhydric isocyanate compound which has a partial structure derived from an aromatic diisocyanate compound, and an isocyanurate ring structure, for example.

When an adhesive composition contains another crosslinking agent, if the content is a range which does not impair the effect of this invention, it will not restrict|limit in particular. It is preferable that it is 5 mass parts or less with respect to 100 mass parts of (meth)acrylic-type copolymers, and, as for content of another crosslinking agent, it is more preferable that it is 1 mass part or less.

«Imidazole compound»

In the present invention, the pressure-sensitive adhesive composition includes at least one N-substituted imidazole compound represented by the following general formula (1). The N-substituted imidazole compound represented by the following general formula (1) may function as a curing accelerator in the pressure-sensitive adhesive composition. Even if the pressure-sensitive adhesive composition contains an N-substituted imidazole compound represented by the following general formula (1), and the pressure-sensitive adhesive layer does not substantially contain an acid component, the curing time can be further shortened while maintaining excellent durability and sufficient useful life. can

In the general formula (1), R ¹ represents an alkyl group, an aryl group or an aralkyl group, and R ² , R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group, an aryl group or an aralkyl group. Also, R ³ and R ⁴ may be linked to each other to form a ring together with the carbon atom to which they are attached.

In the general formula (1), the alkyl group may be linear or pulverized. Moreover, it is preferable that carbon number of an alkyl group is 1-2. In the general formula (1), the aryl group preferably has 6 to 10 carbon atoms, and more preferably a phenyl group or a naphthyl group. In the general formula (1), the aralkyl group preferably consists of an alkylene group having 1 to 2 carbon atoms and an aryl group having 6 to 10 carbon atoms, more preferably a benzyl group or a phenylethyl group.

In the N-substituted imidazole compound represented by the general formula (1), from the viewpoint of shortening the useful life and curing time, R ¹ is an alkyl group or an aralkyl group, R ² is an aryl group, R ³ , and R ⁴ are each independently a hydrogen atom , preferably an alkyl group or an aryl group, more preferably R ¹ is an aralkyl ^{group, R 2} is an aryl group, R ³ , and R ⁴ are each independently a hydrogen atom or an alkyl group, more preferably 1-benzyl-2-phenylimida It is more preferable to sleep.

In the pressure-sensitive adhesive composition, the content of the N-substituted imidazole compound represented by the general formula (1) is preferably 0.01 parts by mass to 0.6 parts by mass, and 0.02 parts by mass to 0.5 parts by mass with respect to 100 parts by mass of the (meth)acrylic copolymer. more preferably.

When the content of the N-substituted imidazole compound represented by the general formula (1) is 0.01 parts by mass or more, the effect of shortening the curing time is excellent. Moreover, a longer useful life can be obtained as content of the N-substituted imidazole compound represented by General formula (1) is 0.6 mass part or less.

≪Ionic compound≫

In the present invention, the pressure-sensitive adhesive composition includes at least one ionic compound (hereinafter also referred to as a specific ionic compound) in which the cation is a metal cation or an organic cation in which the total carbon number of the hydrocarbon group is 7 or more.

An adhesive composition contains a specific ionic compound, and can provide antistatic property, maintaining transparency of an adhesive composition.

Hereinafter, the specific ionic compound of a metal cation whose cation is a specific metal salt is also called. Moreover, the specific ionic compound whose cation is an organic cation whose total carbon number of a hydrocarbon group is 7 or more is also called a specific organic salt.

In the pressure-sensitive adhesive composition, the content of the specific ionic compound is preferably 0.1 parts by mass or more with respect to 100 parts by mass of the (meth)acrylic copolymer, more preferably 0.2 parts by mass or more, and more preferably 0.2 parts by mass to 8 parts by mass. .

When the content of the specific ionic compound is 0.1 parts by mass or more, the effect of improving the antistatic property is more excellent.

(metal salt)

As a cation of a specific metal salt, metal cations, such as an alkali metal and an alkaline-earth metal, are mentioned, for example.

When a metal cation is included as a cation, for example, it is preferable that it is ^{Li +} , Na ⁺ , K ⁺ , and it ^{is more preferable that it is Li + .}

Further, examples of the anion of the specific metal salt include Cl ^- , Br ^- , I ^- , BF ₄ ^- , PF ₆ ^- , SCN ^- , ClO ₄ ^- , CF ₃ COO ^- , SbF ₆ ^- , NbF ₆ ^- , TaF ₆ ^- , F(HF) _n ^- , C ₄ F ₉ SO ₃ ^- , C ₃ F ₇ COO ^- , CF ₃ SO ₃ ^- , (CF ₃ SO ₂ ) ₂ N ^- , (CF ₃ SO ₂ ) ₃ C ^- , (C ₂ F ₅ SO ₂ ) ₂ N ^- , (CF ₃ SO ₂ )(CF ₃ CO)N ^- , AlCl ₄ ^- , Al ₂ Cl ₇ ^- , ClO ₄ ^- , NO ₃ ^- , CH ₃ COO ^- , CH ₃ SO ₃ ^- , AsF ₆ ^- , (CN) ₂ N ^- , (C ₂ F ₅ SO ₂ ) ₂ N ^- , (C ₃ F ₇ SO ₂ ) ₂ N ^- , (C ₄ F ₉ SO ₂ ) ₂ N ^- , (CF ₃ SO ₂ )(C ₂ F ₅ SO ₂ )N ^- , (CF ₃ SO ₂ )(C ₄ F ₉ SO ₂ )N ^- , (C ₂ F ₅ SO ₂ )(C ₄ FOSO ₂ )N ^- and the like.

Among these, ClO ₄ ⁻ and (CF ₃ SO ₂ ) ₂ N ⁻ (hereinafter, also referred to as TFSI) are preferable.

When using a specific metal salt, LiBr, LiI, LiBF ₄ , LiPF ₆ , LiSCN, LiClO ₄ , LiCF ₃ SO ₃ , Li(CF ₃ SO ₂ ) ₂ N, Li(CF _{3 )} A lithium salt such as SO ₂ ) _{3 C is preferably used.}

Moreover, specific metal salt can be used individually by 1 type, and can also be used in combination of 2 or more type.

Examples of the alkaline earth metal salt include calcium salts, magnesium salts, and halides thereof.

(organic salt)

Specific organic salts include cations and anions in which the total number of carbon atoms in the hydrocarbon group is 7 or more.

Total carbon number of the hydrocarbon group which a cation has is 7 or more, Even if it uses together with the polyvalent isocyanate mentioned above, whiteness of an adhesive composition is suppressed, and transparency can be maintained.

As the cation of the specific organic salt, for example, a cation having a backbone such as ammonium, sulfonium, phosphonium, pyridinium, or imidazolium can be used.

If the total carbon number of the hydrocarbon group of the cation is 7 or more, it may be linear, pulverized, or cyclic, and is preferably linear or pulverized from the viewpoint of transparency. In addition, the hydrocarbon group of the cation may have 7 or more total carbon atoms, and may have a plurality of hydrocarbon groups having 7 or less carbon atoms.

It is preferable that carbon number is 11 or more from a transparency viewpoint, and, as for the hydrocarbon group which a cation has, it is more preferable that carbon number is 11 or more and 25 or less.

As a cation in which the total number of carbon atoms of the hydrocarbon group is 7 or more, for example, dodecyltrimethylammonium (15 carbon atoms), octyltrimethylammonium (11 carbon atoms), hexyltrimethylammonium (9 carbon atoms), N-hexyl-4-methylpyridinium ( 7), N-octyl-4-methylpyridinium (9 carbon atoms), amyltriethylammonium (11 carbon atoms), tributylmethylammonium (13 carbon atoms), methyltri-N-octylammonium (25 carbon atoms), cyclohexyl trimethylammonium (C9), etc. are mentioned.

Among them, dodecyltrimethylammonium (15 carbon atoms), octyltrimethylammonium (11 carbon atoms), amyltriethylammonium (11 carbon atoms), tributylmethylammonium (13 carbon atoms), methyltri-N -Octylammonium (25 carbon atoms) is preferred.

Also, as an anion of a specific organic salt, for example, Cl ^- , Br ^- , I ^- , BF ₄ ^- , PF ₆ ^- , SCN ^- , ClO ₄ ^- , (FSO ₂ ) ₂ N ^- , CF ₃ COO ^- , SbF ₆ ^- , NbF ₆ ^- , TaF ₆ ^- , F(HF) _n ^- , C ₄ F ₉ SO ₃ ^- , C ₃ F ₇ COO ^- , CF ₃ SO ₃ ^- , (CF ₃ SO ₂ ) ₂ N ^- , (CF ₃ SO ₂ ) ₃ C ^- , (C ₂ F ₅ SO ₂ ) ₂ N ^- , (CF ₃ SO ₂ )(CF ₃ CO)N ^- , AlCl ₄ ^- , Al ₂ Cl ₇ ^- , ClO ₄ ^- , NO ₃ ^- , CH ₃ COO ^- , CH ₃ SO ₃ ^- , AsF ₆ ^- , (CN) ₂ N ^- , (C ₂ F ₅ SO ₂ ) ₂ N ^- , (C ₃ F ₇ SO ₂ ) ₂ N ^- , (C ₄ F ₉ SO ₂ ) ₂ N ^- , (CF ₃ SO ₂ )(C ₂ F ₅ SO ₂ )N ^- , (CF ₃ SO ₂ )(C ₄ F ₉ SO ₂ )N ^- , (C ₂ F ₅ SO ₂ )(C ₄ FOSO ₂ )N ⁻ and the like.

Among these, PF ₆ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ (hereinafter also referred to as TFSI), and (FSO ₂ ) ₂ N ⁻ (hereinafter also referred to as FSI) are preferable.

When a specific organic salt is used as a specific ionic compound, dodecyltrimethylammonium FSI, octyltrimethylammonium FSI, hexyltrimethylammonium FSI, N-hexyl-4-methylpyridinium FSI, N- Preference is given to octyl-4-methylpyridinium PF ₆ , amyltriethylammonium TFSI, tributylmethylammonium TFSI, methyltri-N-octylammonium TFSI.

In addition, these may be used individually by 1 type, or may be used in combination of 2 or more type.

In the present invention, the pressure-sensitive adhesive composition preferably contains a specific organic salt as a specific ionic compound from the viewpoint of reworkability and metal corrosiveness when manufacturing a polarizing plate or the like.

In the pressure-sensitive adhesive composition, the content of the specific organic salt is preferably 0.1 parts by mass or more with respect to 100 parts by mass of the (meth)acrylic copolymer, more preferably 0.2 parts by mass or more, and more preferably 0.2 parts by mass to 8 parts by mass.

The effect of an antistatic property improvement is more excellent that content of a specific organic salt is 0.1 mass part or more.

≪Silane coupling agent≫

It is preferable that the adhesive composition of this invention contains at least 1 sort(s) of a silane coupling agent further.

Peeling occurs between the pressure-sensitive adhesive layer and the polarizing plate or liquid crystal cell even when the pressure-sensitive adhesive composition contains a silane coupling agent, and a display device (for example, a liquid crystal display) using the pressure-sensitive adhesive composition as the pressure-sensitive adhesive layer of a polarizing plate is exposed to a high temperature and high humidity environment it becomes difficult to do In addition, the pressure-sensitive adhesive composition exhibits better adhesion to smooth glass.

As a silane coupling agent, For example, the silane coupling agent which has polymerizable unsaturated groups, such as vinyltrimethoxysilane, vinyltriethoxysilane, 3-methacryloxypropyl trimethoxysilane; Silane coupling agents which have thiol groups, such as 3-mercaptopropyl trimethoxysilane, 3-mercaptopropyl triethoxysilane, and 3-mercaptopropyl dimethoxymethylsilane; a coupling agent having an epoxy group such as 3-glycidoxypropyltrimethoxysilane trimethoxysilane and 2-(3,4-epoxycyclohexyl)ethyl trimethoxysilane; Silanes having an amino group, such as 3-aminopropyl trimethoxysilane, N-(2-aminoethyl)-3-aminopropyl trimethoxysilane, and N-(2-aminoethyl)-3-aminopropylmethyl dimethoxysilane A coupling agent, tris-(3-trimethoxysilylpropyl)isocyanurate, etc. are mentioned. These may be used individually by 1 type, and may also be used in combination of 2 or more type.

A commercially available silane coupling agent can also be used, and as an example of a commercial item, Shin-Etsu Chemical Co., Ltd. product name "KBM-803", "KBM-802", "X-41-1810", "X-41-1805" ', "X-41-1818", silane coupling agent having a thiol group, "KBM-403", "KBM-303", "KBM-402", "KBE-402", "KBE" manufactured by Shin-Etsu Chemical Co., Ltd. -403" (brand name) etc. which have an epoxy group, etc. can be used suitably.

Among the silane coupling agents, it is preferable to use at least one selected from silane coupling agents having a thiol group from the viewpoint of durability and reworkability, and it is more preferable to use at least one selected from oligomeric silane coupling agents having a thiol group.

The oligomeric type silane coupling agent having a thiol group is preferably a silane coupling agent containing a partial structure having a thiol group and a partial structure not having a thiol group, for example, "X-41-1810" manufactured by Shin-Etsu Chemical Industry Co., Ltd. , "X-41-1805", and "X-41-1818" are mentioned.

When the pressure-sensitive adhesive composition contains a silane coupling agent, the content of the silane coupling agent in the pressure-sensitive adhesive composition is preferably in the range of 0.01 parts by mass to 5 parts by mass, and 0.03 parts by mass to 3 parts by mass with respect to 100 parts by mass of the (meth)acrylic copolymer. The range is more preferable, and the range of 0.05 mass part - 1.0 mass part is still more preferable.

≪Other ingredients≫

In addition to the above components, the pressure-sensitive adhesive composition may further contain, if necessary, a solvent, a weathering stabilizer such as a UV absorber, a tackifier, a plasticizer, a softener, a dye, a pigment, an inorganic filler, and the like. When an adhesive composition contains other components, the content rate can be suitably selected in the range which does not impair the effect of this invention.

<Display device>

The display device of the present invention has at least a touch panel for inputting information, and a polarizing plate with a pressure-sensitive adhesive having a pressure-sensitive adhesive layer formed of the above-described pressure-sensitive adhesive composition of the present invention on the polarizing plate.

≪Touch panel≫

In the present invention, the touch panel is not particularly limited, but as a configuration of the touch panel, for example, an optical material on a sheet having a glass plate and an ITO layer deposited on the glass plate, a cover film as a protective material, an optical material, and a cover The structure which makes the adhesive layer which adhere|attaches between films as a layer of multiple layers is mentioned.

≪Polarizing plate with adhesive≫

The polarizing plate with an adhesive of this invention contains at least a polarizing plate, and the adhesive layer formed on the polarizing plate with the adhesive composition of this invention mentioned above.

Since the polarizing plate with an adhesive of this invention contains the said adhesive layer, transparency and antistatic property are compatible.

In the present invention, the polarizing plate is preferably configured to include at least a polarizer, and only the polarizer may be used, or a laminated polarizer and a protective sheet may be used.

As a polarizer, a polyvinyl alcohol (PVA) film etc. are generally used, for example.

When using what laminated|stacked the polarizer and the protective sheet as a polarizing plate, triacetyl cellulose (TAC), polycycloolefin (COP), an acrylic film etc. can be used as a protective sheet, for example.

What laminated|stacked the polarizer and the sheet|seat for protection is comprised with a two-layer structure (for example, TAC/polarizer) or a three-layer structure (for example, TAC/polarizer/TAC), and can be used as a polarizing plate.

For example, an adhesive layer is provided by providing the adhesive composition of this invention mentioned above to at least one surface of the polarizing plate of the three-layer structure of TAC/polarizer/TAC, and a polarizing plate with an adhesive is produced. When producing a polarizing plate with a pressure-sensitive adhesive, it can be produced by applying a pressure-sensitive adhesive composition on the polarizing plate, but it is preferable to provide and produce on a protective sheet (release sheet) that is peeled off during use as will be described later. The application of the pressure-sensitive adhesive composition can be suitably performed by a coating method such as a dipping method, a coating method, or an inkjet method using a liquid pressure-sensitive adhesive composition. Among them, the coating method is preferable.

Specifically, the pressure-sensitive adhesive composition of the present invention is applied on a release sheet (a protective sheet for an adhesive layer), dried, and an adhesive layer is formed on the release sheet, and then the pressure-sensitive adhesive layer is transferred and cured on a polarizing plate to produce a polarizing plate with an adhesive. . In addition, after the pressure-sensitive adhesive composition of the present invention is applied on a release sheet and dried to form an adhesive layer on the release sheet, the exposed surface of the pressure-sensitive adhesive layer is installed in close contact with the release sheet to prepare a double-sided adhesive tape without a support, After hardening this adhesive layer, the adhesive layer exposed by peeling one peeling sheet is transferred on a polarizing plate, and a polarizing plate with an adhesive may be produced.

The pressure-sensitive adhesive composition provided on the release sheet is preferably dried using a hot air dryer or the like at 70°C to 120°C under drying conditions for about 1 minute to 3 minutes.

Moreover, it is preferable to closely attach and provide the peeling sheet for protecting an exposed surface from a viewpoint of protecting the contact surface with respect to a to-be-adhered body to the exposed surface of the adhesive layer provided on the polarizing plate. As this release sheet, a synthetic resin sheet, such as polyester, which has been subjected to a release treatment with a release agent such as a fluorine-based resin, paraffin wax, or silicone, is preferably used so that the release sheet can be easily removed from the pressure-sensitive adhesive layer. When the paste is applied to the glass plate of the display panel or the like, the release sheet is peeled off and the exposed surface of the pressure-sensitive adhesive layer is brought into close contact with the glass substrate or the like.

In addition, a surface protection sheet for protecting the surface can be further provided on the surface (exposed surface) on the side where the pressure-sensitive adhesive layer of the polarizing plate is not provided. For the surface protection sheet, a protective film or the like in which adhesion is applied to one surface of the PET film is suitably used.

The thickness of the pressure-sensitive adhesive layer is not particularly limited, but the thickness after drying is preferably 1 µm or more and 100 µm or less, more preferably 5 µm or more and 50 µm or less, and still more preferably 15 µm or more and 30 µm or less.

≪Configuration of display device≫

As a structural example of the display apparatus of this invention, the liquid crystal display device with an out-cell type touch panel, the liquid crystal display device with an on-cell type touch panel, etc. are mentioned.

In the liquid crystal display device with an out-cell type touch panel, the polarizing plate with the pressure-sensitive adhesive of the present invention is disposed on both sides of the liquid crystal display panel so that the pressure-sensitive adhesive layer is in contact with the surface of the liquid crystal display panel (for example, the surface of the glass substrate), the pressure-sensitive adhesive A structure in which a polarizing plate is adhered to both sides of a liquid crystal display panel through a layer, and a touch panel is externally attached to a surface other than the liquid crystal display panel side of either polarizing plate (touch panel/adhesive layer/polarizing plate/adhesive layer/liquid crystal display panel/ It is preferable to provide the structure of an adhesive layer/polarizing plate).

The on-cell type liquid crystal display device with a touch panel preferably has a structure in which a touch panel is assembled between a polarizing plate and a liquid crystal display panel (a structure of a polarizing plate/adhesive layer/touch panel/adhesive layer/liquid crystal display panel/adhesive layer/polarizing plate) do. As the display device of the present invention, a display device with an on-cell touch panel is preferable.

Example

Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to these Examples. In addition, unless otherwise indicated, "part" is a mass basis.

(Production Example 1)

98 parts of n-butyl acrylate (BA), 2 parts of 2-hydroxyethyl acrylate (2HEA), and 70 parts of ethyl acetate (EAc) were put in a reactor equipped with a thermometer, a stirrer, a nitrogen inlet pipe and a reflux cooling pipe and mixed. After that, the inside of the reaction vessel was replaced with nitrogen. Thereafter, the mixture in the reaction vessel was heated to 70° C. in a nitrogen atmosphere under stirring, and then 0.02 parts of azobis dimethylvaleronitrile (ABVN) and 200 parts of ethyl acetate (EAc) were sequentially added, followed by reaction for 6 hours. After completion of the reaction, the reaction mixture was diluted with ethyl acetate to obtain a solution of (meth)acrylic copolymer 1 (solid content: 16% by mass).

When the weight average molecular weight (Mw) and number average molecular weight (Mn) of the obtained (meth)acrylic copolymer 1 were measured under the above-mentioned conditions using gel permeation chromatography (GPC), the weight average molecular weight (Mw) was 1.52 million , the degree of dispersion (Mw/Mn) was 6.8.

(Preparation Example 2 ~ Preparation 9)

In Preparation Example 1, (meth)acrylic copolymer 2 ~ A solution of (meth)acrylic copolymer 9 (solid content: 16% by mass) was obtained, respectively.

Further, Mw and Mn were measured for each of the obtained (meth)acrylic copolymers in the same manner as in Production Example 1. The results are shown in Table 1 below.

In Table 1, "BA" is n-butyl acrylate, "PHEA" is phenoxyethyl acrylate, "MA" is methyl acrylate, "t-BA" is t-butyl acrylate, and "2HEA" is 2- Hydroxyethyl acrylate is shown.

<Example 1>

-Preparation of adhesive composition-

As a (meth)acrylic copolymer, 100 parts of the solution of the (meth)acrylic copolymer 1 obtained in Preparation Example 1 above as a solid content, and Colonate 2037 (Nippon Polyurethane Industrial Co., Ltd. product) as a solid content as a polyisocyanate compound (crosslinking agent) 0.125 Part, 0.05 parts of Qazole 1B2PZ (manufactured by Shikoku Chemical Co., Ltd., 1-benzyl-2-phenylimidazole) as an imidazole compound (curing accelerator) as a solid content, X-41-1810 (Shin-Etsu Chemical Industries, Ltd.) as a silane coupling agent The product, an oligomeric type having a thiol group) was sufficiently stirred and mixed with 0.1 parts as a solid content, and 0.1 parts as a solid content of dodecyltrimethylammonium FSI (containing a cation having a hydrocarbon group having 15 carbon atoms) as an ionic compound to obtain a pressure-sensitive adhesive composition.

(cure time)

The time required for the pressure-sensitive adhesive composition obtained above to cure (curing time) was evaluated by measuring the gel fraction as follows.

On the release film (Fujimori Kogyo Co., Ltd. product, 100E-0010N023) which surface-treated the adhesive composition with the silicone type release agent, the film-shaped adhesive layer was produced so that the thickness after drying might be set to 20 micrometers. Next, the prepared pressure-sensitive adhesive layer was moved at 23° C. and 50% RH, and then stored until 168 hours had elapsed. The gel fraction of the pressure-sensitive adhesive layer was measured as follows every 24 hours from the start of storage, respectively. The gel fraction after the elapse of a predetermined storage time is compared with the gel fraction after 168 hours (7 days), and the storage time required for the difference in the gel fraction between the two to be 3% or less is the curing end time, It was evaluated according to the criteria.

The gel fraction was measured by the following method.

1. Paste about 0.25 g of the film-like adhesive layer on a 250 mesh metal net (100 mm × 100 mm) whose mass is accurately measured with a precision balance and surround it so that the gel does not leak. After that, a sample is prepared by accurately measuring the mass with a precision balance.

2. The obtained sample is immersed in 80 ml of ethyl acetate for 3 days.

3. The sample is taken out, washed with a small amount of ethyl acetate, and dried at 120°C for 24 hours. After that, accurately measure the mass with a precision balance.

4. Calculate the gel fraction by the formula below.

Gel fraction (% by mass)=(Z-X)/(Y-X)×100

However, X is the mass of the metal mesh (g), Y is the mass before immersion (g) of the metal mesh to which the adhesive layer is pasted, and Z is the mass (g) of the metal mesh to which the dried adhesive layer is pasted after immersion.

-Evaluation standard-

A: The curing end time is less than 24 hours.

B: The curing completion time is 24 hours or more and less than 48 hours.

C: Curing completion time is 48 hours or more.

(Production of adhesive sheet for testing)

The pressure-sensitive adhesive composition obtained above was applied on a release film (manufactured by Fujimori Kogyo Co., Ltd., 100E-0010N023) surface-treated with a silicone-based release agent, and then dried at 100° C. for 1 minute under drying conditions, 23° C., 50% RH environment. It was cured for 1 day under The thickness of the adhesive layer after completion|finish of hardening was 20 micrometers. Next, on the surface opposite to the release film of the pressure-sensitive adhesive layer, a PET film with a thickness of 100 μm (trade name: A4100, manufactured by Toyo Spinning Co., Ltd.) that has not been subjected to release treatment is overlaid and compressed through a pressurized nip roll. was produced.

(Antistatic properties)

By peeling the release film of the pressure-sensitive adhesive sheet for the test obtained above, the surface resistance value of the pressure-sensitive adhesive layer was measured using R12704 RESISTIVITY CHAMBER (manufactured by Advanced Test Co., Ltd.) under the conditions of 23° C., 50% RH, and applied voltage of 100 V, and the following evaluation criteria According to the evaluation of the antistatic properties. The smaller the surface resistance value, the higher the static electricity generation suppression effect and the better the antistatic property. A and B of the evaluation criteria are practically satisfactory levels.

-Evaluation standard-

A: The surface resistance value is ^{less than 1×10 12} Ω/square.

B: The surface resistance value is 1×10 ¹² Ω/square or more and ^{less than 1×10 13} Ω/square.

C: The surface resistance value is 1×10 ¹³ Ω/square or more.

(transparency)

The test adhesive sheet obtained above was cut to 80 mm x 60 mm to be a sample piece, and the surface of the pressure-sensitive adhesive layer exposed by peeling the release film of the obtained sample piece was placed on a 1.8 mm thick glass plate (trade name: Optical Soda Glass, Matsunami Glass Co., Ltd.) product) and crimped using a table-top laminating machine to obtain a test sample for transparency evaluation. The haze of the obtained test sample for transparency evaluation was measured using the spectrophotometer CM-3500d (made by Konica Minolta Corporation), and transparency was evaluated according to the following evaluation criteria. A and B of the evaluation criteria are practically satisfactory levels.

-Evaluation standard-

A: The haze is less than 0.5.

B: Haze is 0.5 or more and less than 1.0.

C: The haze is 1.0 or more.

(usable life)

The useful life of the pressure-sensitive adhesive composition obtained above was measured by measuring the viscosity as follows, and the viscosity increase rate was calculated and evaluated.

After adjusting the adhesive composition using ethyl acetate so that it might become a viscosity of 1500 mPa*s, the viscosity (a) was measured at 25 degreeC, 1 minute, and 10 rpm with a BH type rotational viscometer. In addition, after leaving it to stand for 24 hours in an airtight container under the conditions of 25 degreeC and 50%RH, the viscosity (b) was measured with a BH-type rotational viscometer at 25 degreeC, 1 minute, and 10 rpm.

Using the obtained viscosity (a) and viscosity (b), the viscosity increase rate (%) was calculated by the following formula.

Viscosity increase rate (%) = Viscosity (b) after leaving for 24 hours / Viscosity immediately after mixing (a) x 100

-Evaluation standard-

A: The viscosity increase rate (%) is less than 110%.

B: Viscosity increase rate (%) is 110% or more and less than 120%.

C: The viscosity increase rate (%) is 120% or more.

<Examples 2 to 18 and Comparative Examples 1 to 5>

Except for changing the composition of the pressure-sensitive adhesive composition in Example 1 as shown in Table 2 and Table 3 below, the pressure-sensitive adhesive composition was prepared in the same manner as in Example 1, and evaluation was performed in the same manner as in Example 1. The evaluation results are shown in Tables 2 and 3.

The abbreviation in Table 2 and Table 3 is as showing below, and a compounding quantity is a solid content conversion value.

(crosslinking agent)

Colonate 2037: Nippon Polyurethane Industrial Co., Ltd. product, isocyanurate form of tolylene diisocyanate

Colonate L: Nippon Polyurethane Industrial Co., Ltd. product, trimethylolpropane adduct body of tolylene diisocyanate

(curing accelerator)

1B2PZ: Shikoku Chemical Industry Co., Ltd. product, 1-benzyl-2-phenylimidazole

(Silane coupling agent)

X-41-1810: Shin-Etsu Chemical Co., Ltd. product, oligomeric type having a thiol group

(ionic compounds)

In Tables 2 and 3, FSI denotes fluorosulfonylimide ((FSO ₂ ) ₂ N ⁻ ), and TFSI denotes trifluoromethanesulfonylimide ((CF ₃ SO ₂ ) ₂ N ⁻ ).

In Tables 2 and 3, for example, a description indicated by "C15" indicates that the total number of carbon atoms in the hydrocarbon group of the cation is 15.

As shown in Tables 2 and 3, it can be seen that in Examples, transparency and antistatic properties were excellent and curing time was shortened. As in Comparative Example 2 and Comparative Example 3, when an ionic compound having a total number of carbon atoms of the hydrocarbon group in the cation is less than 7, it can be seen that transparency is lowered. It turns out that hardening time cannot be shortened when crosslinking agents other than the polyisocyanate compound which have the partial structure derived from an aromatic diisocyanate compound and an isocyanurate ring structure are used like Comparative Example 4. It turns out that hardening time cannot be shortened in the composition which does not contain the N-substituted imidazole compound (hardening accelerator) represented by General formula (1) like Comparative Example 5.

Claims (6)

(meth)acrylic copolymer containing a structural unit derived from a monomer having a hydroxyl group;
polyvalent isocyanate compounds having a partial structure derived from an aromatic diisocyanate compound and an isocyanurate ring structure;
an N-substituted imidazole compound represented by the following general formula (1); and
Dodecyltrimethylammonium FSI, octyltrimethylammonium FSI, hexyltrimethylammonium FSI, N-hexyl-4-methylpyridinium FSI, N-octyl-4-methylpyridinium PF ₆ , amyltriethylammonium TFSI, tributylmethylammonium TFSI and at least one ionic compound selected from the group consisting of methyltri-N-octylammonium TFSI;
The cation of the ionic compound is a metal cation or an organic cation in which the total carbon number of the hydrocarbon group is 7 or more.
[Formula 1]

General formula (1)
In the formula, R ¹ represents an alkyl group, an aryl group or an aralkyl group,
In the formula, R ² , R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group, an aryl group or an aralkyl group,
R ³ and R ⁴ may be connected to each other to form a ring. The method according to claim 1,
The pressure-sensitive adhesive composition in which the content of the ionic compound is 0.1 parts by mass or more with respect to 100 parts by mass of the (meth)acrylic copolymer. The method according to claim 1 or 2,
The content of the N-substituted imidazole compound is 0.01 parts by mass to 0.6 parts by mass based on 100 parts by mass of the (meth)acrylic copolymer, the pressure-sensitive adhesive composition. The method according to claim 1 or 2,
The content of the polyvalent isocyanate compound is 0.01 parts by mass to 0.5 parts by mass with respect to 100 parts by mass of the (meth)acrylic copolymer, the pressure-sensitive adhesive composition. The method according to claim 1 or 2,
The (meth)acrylic copolymer is a pressure-sensitive adhesive composition having a structural unit derived from a monomer having a hydroxyl group from 0.3% by mass to 12% by mass. touch panel; and
A display device having a;