JP2020012098A - Adhesive composition, and adhesive including the same, adhesive for polarizing plate, and image display device - Google Patents

Abstract

To provide an adhesive composition that can achieve both of high antistatic performance and durability even under a severe high-temperature environment, when used as an adhesive for bonding between a polarizing plate (protection film) and a glass face of a liquid crystal cell, or the like, in the production of an image display device.SOLUTION: An adhesive composition contains an acrylic resin (A) containing a structural site derived from a macromonomer (a1) and an ionic compound (B). Relative to the acrylic resin (A) 100 pts.wt., the ionic compound (B) is 3-20 pts.wt. The ionic compound (B) has a melting point of 30°C or more.SELECTED DRAWING: None

Description

  The present invention relates to a pressure-sensitive adhesive composition, a pressure-sensitive adhesive using the same, a pressure-sensitive adhesive for a polarizing plate, and an image display device, and more specifically, a pressure-sensitive adhesive capable of achieving both high antistatic performance and durability even in a high-temperature environment. The present invention relates to a pressure-sensitive adhesive composition forming an agent, a pressure-sensitive adhesive using the same, a pressure-sensitive adhesive for a polarizing plate, and an image display device.

  Conventionally, a polarizer composed of a polarizer made of a polyvinyl alcohol-based film or the like having polarizability is laminated on a surface of a liquid crystal cell in which a liquid crystal component oriented between two glass plates is sandwiched between two glass plates. Liquid crystal display devices have been manufactured. The lamination of the polarizing plate on the surface of the liquid crystal cell is usually performed by abutting and pressing the pressure-sensitive adhesive layer provided on the surface of the polarizing plate against the surface of the liquid crystal cell.

  The adhesive used for bonding such a polarizing plate (protective film) and a liquid crystal cell (glass plate) has, for example, durability such that it does not float or peel off from the liquid crystal cell (glass plate) under a high temperature environment. It has been demanded.

  For the purpose of improving the durability, a pressure-sensitive adhesive using an acrylic resin copolymerized with a macromonomer has been proposed (for example, see Patent Document 1).

  Further, since the liquid crystal cell is driven by controlling the voltage, problems such as display unevenness and failure occur due to static electricity. Since static electricity is generated when an adhesive film is bonded or peeled off, it is required that the adhesive has antistatic performance as a countermeasure against static electricity.

  Further, in recent years, the liquid crystal cell has become thinner, and the warpage of the liquid crystal cell in a high-temperature environment has become a problem, and a high stress relaxation property has also been required for an adhesive for attaching a polarizing plate to the liquid crystal cell. ing.

  As described above, as an adhesive having both the warpage suppressing performance and the antistatic performance of a liquid crystal cell, an adhesive combining an acrylic resin using a macromonomer and an ionic compound has been proposed (for example, Patent Document 2). reference.).

  It is also known that a pressure-sensitive adhesive using a macromonomer is useful as a pressure-sensitive adhesive for touch panels, and that a pressure-sensitive adhesive having excellent antistatic performance can prevent malfunction of a touch panel (for example, Patent Document 3 and See Patent Document 4.).

JP-A-8-209095 WO 2015/141382 JP 2013-18227 A JP 2013-105154 A

  However, in the pressure-sensitive adhesives described in Patent Literature 1 and Patent Literature 2, it is necessary to use a large amount of an ionic compound in order to impart the high antistatic performance required in recent years. There was a problem that the restriction of the molecular chain was canceled out by the plasticization of the pressure-sensitive adhesive by the ionic compound, and the durability was reduced.

  Further, in the pressure-sensitive adhesives described in Patent Documents 3 and 4, in order to further enhance antistatic performance, a large amount of an ionic compound is contained, but in a pressure-sensitive adhesive containing a large amount of an ionic compound, However, the durability in a high temperature environment is not sufficient. For this reason, there is a demand for further improvement such that excellent antistatic performance and durability can be achieved even when a large amount of an ionic compound is contained.

  Thus, in the present invention, in such a background, for example, when a metal such as a glass or a conductive layer used for an image display member such as a liquid crystal cell is used as an adherend, a high charge can be obtained even in a severe high temperature environment. An object of the present invention is to provide a pressure-sensitive adhesive composition that forms a pressure-sensitive adhesive that can achieve both prevention performance and durability, and a pressure-sensitive adhesive, a pressure-sensitive adhesive for a polarizing plate, and an image display device using the same.

  However, the present inventors have conducted intensive studies in view of such circumstances, and as a result, have found that a pressure-sensitive adhesive composition containing an acrylic resin (A) containing a structural portion derived from a macromonomer (a1) and an ionic compound (B) In the case where the ionic compound (B) contains a large amount of the ionic compound (B), the durability is reduced. However, by using an ionic compound having a high melting point as the ionic compound (B), the molecule derived from the macromonomer (a1) It was found that the entanglement of the chains was not easily affected by the plasticization by the ionic compound (B), and the entanglement was maintained. Thus, it was found that an adhesive capable of achieving both high antistatic performance and high durability was obtained, and completed the present invention. did.

  That is, the gist of the present invention is a pressure-sensitive adhesive composition containing an acrylic resin (A) containing a structural portion derived from a macromonomer (a1) and an ionic compound (B), wherein the acrylic resin (A) A pressure-sensitive adhesive composition comprising 3 to 20 parts by weight of the ionic compound (B) based on 100 parts by weight, and wherein the ionic compound (B) is an ionic compound having a melting point of 30 ° C. or more. It is about.

  Furthermore, the present invention relates to a pressure-sensitive adhesive, a pressure-sensitive adhesive for a polarizing plate, and an image display device using the pressure-sensitive adhesive composition.

  The pressure-sensitive adhesive obtained using the pressure-sensitive adhesive composition of the present invention can achieve both high antistatic performance and high durability even in a high-temperature environment. And the adhesive composition of this invention can obtain the adhesive suitable for various uses, especially a polarizing plate.

  Further, when the macromonomer (a1) is an acrylic macromonomer having a structure derived from an alkyl (meth) acrylate and a polar group-containing (meth) acrylate, it is excellent in compatibility with other monomers and easily copolymerized. Is preferred.

  When the number average molecular weight of the macromonomer (a1) is 1,000 to 50,000, an adhesive having excellent mechanical properties and durability can be obtained.

  When the content of the macromonomer (a1) is 0.1 to 10% by weight with respect to the polymerization component constituting the acrylic resin (A), a pressure-sensitive adhesive excellent in balance between antistatic performance and durability can be obtained. Become like

  When the acrylic resin (A) is an acrylic resin obtained by polymerizing a polymerization component containing the polar group-containing monomer (a3), the reactivity with the crosslinking agent becomes excellent.

  When the acid value of the acrylic resin (A) is 30 mgKOH / g or less, a pressure-sensitive adhesive excellent in heat stability can be obtained.

  When the ionic compound (B) is at least one of a nitrogen-containing onium salt and an alkali metal salt, the ionic compound (B) is easily compatible and a pressure-sensitive adhesive excellent in heat resistance can be obtained.

  Furthermore, when the crosslinking agent (C) is contained, a crosslinked structure can be formed, and a pressure-sensitive adhesive having more excellent durability can be obtained.

  Further, when the silane coupling agent (D) is contained, a pressure-sensitive adhesive having more excellent durability can be obtained.

  Since the pressure-sensitive adhesive of the present invention is obtained by cross-linking the pressure-sensitive adhesive composition with a cross-linking agent (C), the pressure-sensitive adhesive has more excellent antistatic performance and durability.

When the surface resistivity of the pressure-sensitive adhesive layer in the pressure-sensitive adhesive is less than 1.0 × 10 ¹⁰ Ω / cm ² , the antistatic performance is further improved.

  In addition, when the pressure-sensitive adhesive is used as a pressure-sensitive adhesive for bonding a polarizing plate (protective film) to an image display member such as a liquid crystal cell (glass plate) or a metal surface (conductive layer), good antistatic performance is obtained. And high durability, the pressure-sensitive adhesive of the present invention is very useful as a pressure-sensitive adhesive for polarizing plates.

  An image display device in which a polarizing plate and an image display member such as a liquid crystal cell are bonded to each other with the above-mentioned pressure-sensitive adhesive does not cause display unevenness or peeling due to static electricity and has excellent quality.

Hereinafter, the present invention will be described in detail.
In the present invention, “(meth) acryl” means acryl or methacryl, “(meth) acryloyl” means acryloyl or methacryloyl, and “(meth) acrylate” means acrylate or methacrylate. . The “acrylic resin” is a resin obtained by polymerizing a polymerization component containing at least one (meth) acrylate monomer.

  The pressure-sensitive adhesive composition of the present invention contains an acrylic resin (A) containing a structural part derived from a macromonomer (a1) and an ionic compound (B).

<Acrylic resin (A)>
The acrylic resin (A) used in the present invention is a resin obtained by polymerizing and containing a macromonomer (a1) as a polymerization component. In addition to the macromonomer (a1), (meth) acrylic acid Polymerization containing an alkyl ester (a2), preferably a polar group-containing monomer (a3) (excluding the macromonomer (a1)), and if necessary, other copolymerizable monomers (a4). An acrylic resin obtained by polymerizing the components can be used.

[Macromonomer (a1)]
The macromonomer (a1) refers to a high molecular weight monomer having a polymerizable functional group, and particularly preferably has a polymerizable unsaturated group at a terminal of a polymer chain.

  The number average molecular weight (Mn) of the macromonomer (a1) is preferably from 1,000 to 50,000 in view of the mechanical properties and durability of the obtained pressure-sensitive adhesive. The lower limit of Mn of the macromonomer (a1) is more preferably 2,000 or more, further preferably 3,000 or more, and particularly preferably 3,500 or more. Further, the upper limit of Mn of the macromonomer (a1) is more preferably 30,000 or less, further preferably 20,000 or less, and particularly preferably 10,000 or less. When Mn is equal to or larger than the lower limit, the cohesive force when the acrylic resin (A) is used is easily improved, and the durability tends to be excellent, which is preferable. On the other hand, when Mn is equal to or less than the upper limit, the coating adequacy of the resin solution becomes good, and a uniform coating film tends to be easily obtained.

  The number average molecular weight (Mn) is a number average molecular weight in terms of standard polystyrene molecular weight. A high performance liquid chromatograph (manufactured by Waters, "ACQUITY APC system") has one column: ACQUITY APC XT 450, ACQUITY. The measurement is performed by using one APC XT 200 and two ACQUITY APC XT 45 connected in series.

The glass transition temperature (Tg) of the macromonomer (a1) is preferably from -100 to 150C, more preferably from -70 to 130C, and still more preferably from -50 to 120C from the viewpoint of durability.
When the glass transition temperature of the macromonomer (a1) is 0 ° C. or lower, the antistatic performance of the pressure-sensitive adhesive using the acrylic resin (A) obtained by copolymerizing the macromonomer (a1) tends to be excellent.
The glass transition temperature (Tg) of the macromonomer (a1) can be calculated, for example, from the Fox unit described later from the monomer units constituting the macromonomer (a1) and the content ratio thereof.

[Raw material monomer of macromonomer (a1)]
As a raw material monomer for obtaining the macromonomer (a1), for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, n-butyl (meth) A) alkyl (meth) acrylates such as acrylate, i-butyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-lauryl (meth) acrylate, and n-stearyl (meth) acrylate ;
Hydroxyl-containing (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and glycerol (meth) acrylate;
(Meth) acrylic acid, 2- (meth) acryloyloxyethylhexahydrophthalic acid, 2- (meth) acryloyloxypropylhexahydrophthalic acid, 2- (meth) acryloyloxyethylphthalic acid, 2- (meth) acryloyloxy Propylphthalic acid, 2- (meth) acryloyloxyethylmaleic acid, 2- (meth) acryloyloxypropylmaleic acid, 2- (meth) acryloyloxyethylsuccinic acid, 2- (meth) acryloyloxypropylsuccinic acid, crotonic acid Carboxy group-containing vinyl monomers such as, fumaric acid, maleic acid, itaconic acid, monomethyl maleate, monomethyl itaconate;
Vinyl monomers containing acid anhydride groups such as maleic anhydride and itaconic anhydride;
Epoxy-containing vinyl monomers such as glycidyl (meth) acrylate, glycidyl α-ethyl acrylate, and 3,4-epoxybutyl (meth) acrylate;
Amino group-containing (meth) acrylate-based vinyl monomers such as dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate;
(Meth) acrylamide, Nt-butyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, diacetone acrylamide, maleic amide, maleimide Vinyl monomers containing an amide group, such as
Vinyl monomers such as styrene, α-methylstyrene, vinyl toluene, (meth) acrylonitrile, vinyl chloride, vinyl acetate, and vinyl propionate;
Divinylbenzene, ethylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) ) Acrylate, tripropylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, allyl (meth) acrylate,
And the like.
These raw material monomers can be used alone or in combination of two or more.

  It is preferable from the viewpoint of durability that the side chain of the macromonomer (a1) has a polar group. Examples of the raw material monomer capable of having a polar group in the side chain include a hydroxyl group-containing (meth) acrylate. , A carboxy group-containing vinyl monomer, an acid anhydride group-containing vinyl monomer, an amino group-containing (meth) acrylate vinyl monomer, and an amide group-containing vinyl monomer. At least one selected polar group-containing monomer is used, and among the polar group-containing monomers, a hydroxyl group-containing (meth) acrylate is preferable from the viewpoint of durability.

  Furthermore, it is particularly preferable to use an alkyl (meth) acrylate and a polar group-containing (meth) acrylate as a raw material monomer of the macromonomer (a1). It is an acrylic macromonomer having a structure derived from a group-containing (meth) acrylate, and in particular, an acrylic macromonomer obtained by polymerizing the alkyl (meth) acrylate and the polar group-containing (meth) acrylate. This is particularly preferred from the viewpoint of

  And among the said raw material monomers, it is preferable to contain a (meth) alkyl acrylate having 1 to 8 carbon atoms and a hydroxyl group-containing (meth) acrylate, and further, methyl (meth) acrylate, n-butyl (meth) acrylate and It is preferable to use 2-hydroxyethyl (meth) acrylate from the viewpoint of compatibility with other copolymer components (a2) to (a4) and copolymerizability.

  The content of the macromonomer (a1) is preferably 0.1 to 10% by weight, particularly preferably 0.2 to 5% by weight, and more preferably 0.2 to 5% by weight, based on the polymerization component constituting the acrylic resin (A). Preferably it is 0.5 to 2% by weight. When the content is within the above range, the balance between the antistatic performance and the durability becomes better.

[(Meth) acrylic acid alkyl ester (a2)]
Examples of the (meth) acrylic acid alkyl ester (a2) include, for example, those having usually 1 to 20 (preferably 1 to 18, particularly preferably 1 to 12, and more preferably 1 to 8) carbon atoms in the alkyl group; Preferred are aliphatic (meth) acrylic acid alkyl esters, and specifically, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, t-butyl (meth) acrylate, n-propyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isodecyl (meth) acrylate, lauryl (meth) Acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, etc. And the like. These may be used alone or in combination of two or more.

  Among these (meth) acrylic acid alkyl esters (a2), methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, 2- Ethylhexyl (meth) acrylate is preferred, and n-butyl (meth) acrylate is particularly preferred.

  The content of the alkyl (meth) acrylate (a2) is preferably at least 10% by weight, more preferably at least 30% by weight, based on the polymerization component constituting the acrylic resin (A). , More preferably 50 to 99.9% by weight, particularly preferably 60 to 99.9% by weight. If the content is too small, the adhesive properties and durability tend to decrease.

  In addition, methyl (meth) acrylate, ethyl (meth) acrylate, and n-butyl (meth) acrylate are used as a polymerization component constituting the acrylic resin (A) in terms of excellent compatibility with the ionic compound (B). It is preferable that the content is at least 10% by weight, more preferably at least 30% by weight, based on the polymerization component constituting the acrylic resin (A). Preferably it is 40 to 99.9% by weight.

[Polar group-containing monomer (a3)]
Next, the polar group-containing monomer (a3) will be described.
The polar group-containing monomer (a3) in the present invention refers to a copolymerizable ethylenically unsaturated monomer such as a hydroxyl group-containing monomer, a carboxy group-containing monomer, and a nitrogen atom-containing monomer other than the macromonomer (a1). These can be used alone or in combination of two or more. In the present invention, it is preferable to contain at least one selected from a hydroxyl group-containing monomer, a carboxy group-containing monomer, and a nitrogen atom-containing monomer.

  Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 5-hydroxypentyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, and 8-hydroxyoctyl ( Hydroxyalkyl acrylates such as meth) acrylate; caprolactone-modified monomers such as caprolactone-modified 2-hydroxyethyl (meth) acrylate; oxyalkylene-modified monomers such as diethylene glycol (meth) acrylate and polyethylene glycol (meth) acrylate; 2-acryloy Primary hydroxyl group-containing monomers such as roxyethyl-2-hydroxyethylphthalic acid, N-methylol (meth) acrylamide, and hydroxyethylacrylamide; Secondary hydroxyl group-containing monomers such as xypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate and 3-chloro-2-hydroxypropyl (meth) acrylate; hydroxyl groups such as 2,2-dimethyl 2-hydroxyethyl (meth) acrylate Contained monomers. These may be used alone or in combination of two or more.

  Among the above hydroxyl group-containing monomers, a primary hydroxyl group-containing monomer is preferable in that it has excellent reactivity with the cross-linking agent (C), and 2-hydroxyethyl (meth) acrylate is preferable in terms of stability during polymerization, and a cross-linking agent ( It is preferable to use 4-hydroxybutyl (meth) acrylate in that the reactivity with C) is fast and the aging is short. Further, 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate are preferable since impurities such as di (meth) acrylate and the like at the time of preparing the monomer are small, and those having high purity can be obtained and are easily manufactured.

  When the hydroxyl group-containing monomer is prepared and used, or when a commercially available product is used, it is also preferable to use one having an impurity of di (meth) acrylate of 0.5% by weight or less, particularly preferably. It is at most 0.2% by weight, more preferably at most 0.1% by weight, and specifically, 2-hydroxyethyl acrylate, 4-hydroxybutyl acrylate and 2-hydroxypropyl acrylate having such an impurity amount are particularly preferred.

  Examples of the carboxy group-containing monomer include dimer acid of acrylic acid such as (meth) acrylic acid and β-carboxyethyl acrylate. Among them, (meth) acrylic acid is preferred in view of heat resistance and stability during polymerization. Acrylic acid is preferred.

  Examples of the nitrogen atom-containing monomer include an amino group-containing monomer, an amide group-containing monomer, and other nitrogen atom-containing monomers.

Examples of the amino group-containing monomer include a primary amino group-containing monomer such as aminomethyl (meth) acrylate and aminoethyl (meth) acrylate, a secondary amino group-containing monomer such as t-butylaminoethyl (meth) acrylate, Tertiary amino group-containing monomers such as ethylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, and diethylaminoethyl (meth) acrylate are exemplified.
Among the above-mentioned amino group-containing monomers, tertiary amino group-containing monomers are preferable in terms of high crosslinking promoting effect and high storage stability of the resin.

  Examples of the amide group-containing monomer include (meth) acrylamide; methoxymethyl (meth) acrylamide, ethoxymethyl (meth) acrylamide, propoxymethyl (meth) acrylamide, isopropoxymethyl (meth) acrylamide, and n-butoxymethyl (meth). ) Alkoxyalkyl (meth) acrylamide monomers such as acrylamide and isobutoxymethyl (meth) acrylamide; dialkyl (meth) acrylamide monomers such as dimethyl (meth) acrylamide and diethyl (meth) acrylamide; N- (hydroxymethyl) acrylamide And a heterocyclic amide monomer such as (meth) acryloylmorpholine.

  Among the amide group-containing monomers, (meth) acryloylmorpholine, alkoxyalkyl (meth) acrylamide-based monomers, dialkyl (meth) acrylamide in terms of stability of the resin solution and suppression of migration of the ionic compound (B) A system monomer is preferred.

  Among the above various polar group-containing monomers (a3), it is preferable to have a hydroxyl group-containing monomer from the viewpoint of excellent reactivity with the crosslinking agent (C).

  The molecular weight of the polar group-containing monomer (a3) is preferably 500 or less from the viewpoint of easy crosslinking reaction. The lower limit of the molecular weight is usually 50.

The polar group-containing monomer (a3) is preferably contained in an amount of 30% by weight or less based on a polymerization component (hereinafter, simply referred to as a “polymerization component”) constituting the acrylic resin (A). When a hydroxyl group-containing monomer is used, its content is preferably from 0.01 to 30% by weight, more preferably from 0.1 to 20% by weight, particularly from 1 to 15% by weight, particularly from 1 to 15% by weight, in view of durability and reworkability. Is preferably 3 to 10% by weight.
Among the polar group-containing monomers (a3), particularly when a carboxy group-containing monomer is used, its content is preferably 0.01 to 10% by weight with respect to the polymerization component in view of durability and reworkability. 0.1-5% by weight is preferred. Further, in terms of corrosion resistance and suppression of hydrolysis of the substrate and the adherend, the content is preferably 0.5% by weight or less, more preferably 0.2% by weight or less, particularly preferably 0.1% by weight or less based on the polymerization component. It is preferably at most 1% by weight.
Among the polar group-containing monomers (a3), particularly when a nitrogen atom-containing monomer is used, its content is preferably 0.1 to 10% by weight with respect to the polymerization component from the viewpoint of durability and suppression of hydrolysis. Is preferably 0.5 to 5% by weight.

[Other copolymerizable monomers (a4)]
The other copolymerizable monomer (a4) is a copolymerizable ethylenically unsaturated monomer, for example, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenoxydiethylene glycol (meth) acrylate, 2-hydroxy Aromatic ring-containing monomers such as -3-phenoxypropyl (meth) acrylate and orthophenylphenoxyethyl (meth) acrylate; cyclohexyl (meth) acrylate, cyclohexyloxyalkyl (meth) acrylate, t-butylcyclohexyloxyethyl (meth) Alicyclic-containing monomers such as acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate; 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, -Methoxybutyl (meth) acrylate, 2-butoxyethyl (meth) acrylate, 2-butoxydiethylene glycol (meth) acrylate, methoxydiethylene glycol (meth) acrylate, methoxytriethylene glycol (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, methoxy Dipropylene glycol (meth) acrylate, methoxy polyethylene glycol (meth) acrylate, octoxy polyethylene glycol-polypropylene glycol mono (meth) acrylate, lauroxy polyethylene glycol mono (meth) acrylate, stearoxy polyethylene glycol mono (meth) acrylate, etc. And other ether chain-containing monomers. These may be used alone or in combination of two or more.

  Among them, the point that the refractive index and the birefringence can be easily adjusted, and the light leakage resistance (light leakage resistance means that when used as an adhesive for bonding a polarizing plate to a liquid crystal cell or the like, the backlight after a high temperature or wet heat test is used. Is preferred. In terms of excellent performance, aromatic ring-containing monomers are preferable, and benzyl (meth) acrylate, phenoxy (meth) ethyl acrylate, and phenoxydiethylene glycol (meth) acrylate are particularly preferable. An alicyclic-containing monomer is preferred in that it can easily adjust the refractive index and the birefringence, and has excellent adhesion to a low-polarity adherend (for example, cycloolefin or the like).

  The content of the other copolymerizable monomer (a4) is preferably 25% by weight or less based on the amount of the polymerization component so as not to impair the effects of the present invention.

  The acrylic resin (A) used in the present invention is a macromonomer (a1), preferably further an alkyl (meth) acrylate (a2), a polar group-containing monomer (a3), and other copolymerizable monomers (a4). Can be produced, for example, by mixing or dropping such a polymerization component and a polymerization initiator in an organic solvent, using a polymerization component obtained by appropriately selecting and combining the above.

  The above polymerization reaction can be performed by a conventionally known polymerization method such as solution radical polymerization, suspension polymerization, bulk polymerization, emulsion polymerization, among which solution radical polymerization and bulk polymerization are preferred, and particularly preferred is solution radical polymerization. It is polymerization.

  Examples of the organic solvent used in the polymerization reaction include aromatic hydrocarbons such as toluene and xylene, aliphatic hydrocarbons such as hexane, esters such as ethyl acetate and butyl acetate, n-propyl alcohol, and isopropyl alcohol. And ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone.

Among these organic solvents, ethyl acetate, acetone, methyl ethyl ketone, butyl acetate, toluene, and methyl are preferred because of the ease of polymerization reaction, the effect of chain transfer, the ease of drying when applying an adhesive, and the high level of safety. Isobutyl ketone is preferably used, and particularly preferably, ethyl acetate, acetone and methyl ethyl ketone. These organic solvents may be used alone or in combination of two or more.
And the usage-amount of these organic solvents is 10-900 weight part normally with respect to 100 weight part of polymerization components.

Examples of the polymerization initiator used in the solution radical polymerization include, for example, 2,2′-azobisisobutyronitrile and 2,2′-azobis-2-methylbutyronitrile which are ordinary radical polymerization initiators Azo initiators, such as benzoyl peroxide, lauroyl peroxide, di-t-butyl peroxide, cumene, 4,4'-azobis (4-cyanovaleric acid) and 2,2'-azobis (methylpropionic acid) Organic peroxides such as hydroperoxide and the like can be mentioned, and they can be appropriately selected and used according to the monomers used. These polymerization initiators may be used alone or in combination of two or more.
And the usage-amount of these polymerization initiators is 0.01 to 5 weight% normally with respect to a polymerization component.

  The acid value of the acrylic resin (A) thus obtained is preferably 30 mgKOH / g or less, particularly preferably 10 mgKOH, from the viewpoint of thermal stability, low metal corrosiveness, and excellent antistatic performance. / G or less, more preferably 5 mgKOH / g or less, particularly preferably 1 mgKOH / g or less.

  Here, the acid value in the present invention is determined by a neutralization titration method using potassium hydroxide or a potentiometric method.

  The weight average molecular weight of the acrylic resin (A) is preferably from 200,000 to 3,000,000, particularly preferably from 400,000 to 2,000,000, more preferably from 600,000 to 1,800,000, particularly preferably from 800,000 to 800,000. 1.6 million. If the weight-average molecular weight is too small, the durability tends to decrease.If the weight-average molecular weight is too large, a large amount of a diluting solvent is required at the time of production, the drying property is reduced, and the remaining solvent is increased in the pressure-sensitive adhesive layer and the durability is reduced. Tend to.

The degree of dispersion (weight average molecular weight / number average molecular weight) of the acrylic resin (A) is preferably 20 or less, particularly preferably 15 or less, and more preferably 10 or less.
If the degree of dispersion is too high, reworkability and durability tend to decrease. The lower limit of the degree of dispersion is usually 1.

The weight-average molecular weight is a weight-average molecular weight in terms of standard polystyrene molecular weight, and is applied to a high-performance liquid chromatograph (“Waters 2695 (body)” and “Waters 2414 (detector)” manufactured by Waters Japan) as a column. : Shodex GPC KF-806L (exclusion limit molecular weight: 2 × 10 ⁷ , separation range: 100 to 2 × 10 ⁷ , theoretical plate number: 10,000 plates / unit, filler material: styrene-divinylbenzene copolymer, filler Particle size: 10 μm) is measured by connecting three in series, and the number average molecular weight can be measured by the same method. The degree of dispersion is determined from the weight average molecular weight and the number average molecular weight.

  The acrylic resin (A) preferably has a glass transition temperature (Tg) of -100 to 10C, particularly preferably -70 to 0C, and more preferably -65 to -25C. If the glass transition temperature is too high, the antistatic performance tends to decrease. If the glass transition temperature is too low, the ionic compound (B) as an antistatic agent tends to move and bleed, resulting in a decrease in durability.

Ｔｇ：アクリル系樹脂（Ａ）のガラス転移温度（Ｋ）
Ｔga：モノマーＡのホモポリマーのガラス転移温度（Ｋ） Ｗａ：モノマーＡの重量分率Ｔgb：モノマーＢのホモポリマーのガラス転移温度（Ｋ） Ｗｂ：モノマーＢの重量分率Ｔgn：モノマーＮのホモポリマーのガラス転移温度（Ｋ） Ｗｎ：モノマーＮの重量分率（Ｗａ＋Ｗｂ＋・・・＋Ｗｎ＝１） The glass transition temperature (Tg) is calculated by the following Fox equation.

Tg: glass transition temperature (K) of acrylic resin (A)
Tga: Glass transition temperature of homopolymer of monomer A (K) Wa: Weight fraction of monomer A Tgb: Glass transition temperature of homopolymer of monomer B (K) Wb: Weight fraction of monomer B Tgn: Homopolymer of monomer N Glass transition temperature (K) of polymer Wn: weight fraction of monomer N (Wa + Wb +... + Wn = 1)

That is, the glass transition temperature (Tg) of the acrylic resin (A) is defined by applying the glass transition temperature and the weight fraction when each monomer constituting the acrylic resin (A) is a homopolymer to the Fox equation. It is a value calculated by
Incidentally, the glass transition temperature when the monomer constituting the acrylic resin (A) is a homopolymer is usually measured by a differential scanning calorimeter (DSC), and is defined by JIS K7121-1987 and JIS K6240. Can be measured by a method conforming to.

The viscosity of the acrylic resin (A) is adjusted by a solvent or the like, and the acrylic resin (A) is used as a solution of the acrylic resin (A) in the pressure-sensitive adhesive composition of the present invention. The viscosity of the acrylic resin (A) solution is preferably from 500 to 20,000 mPa · s, particularly preferably from 1,000 to 18,000 mPa · s, and still more preferably from 2,0 mPa · s from the viewpoint of easy handling. 000-15,000 mPa · s.
If the viscosity is too high, the fluidity tends to decrease and handling becomes difficult. If the viscosity is too low, coating tends to be difficult when the adhesive is used.

  The viscosity of the acrylic resin (A) solution is measured by a rotational viscosity method using a B-type viscometer on a resin solution adjusted to 25 ° C.

  Thus, the acrylic resin (A) used in the present invention is obtained.

<Ionic compound (B)>
The pressure-sensitive adhesive composition of the present invention further contains an ionic compound (B) from the viewpoint of measures against static electricity.
The ionic compound (B) is a compound composed of a cation component and an anion component, and is a compound composed of a combination of an organic cation or an inorganic cation as a cation component and a combination of an organic anion or an inorganic anion as an anion component. The ionic compound (B) may be used alone or in combination of two or more.

As the inorganic cation, an alkali metal cation is preferable in terms of antistatic performance, and a lithium cation is particularly preferable.
Examples of the organic cation include a pyridinium cation, a piperidinium cation, a pyrrolidinium cation, a cation having a pyrroline skeleton, a cation having a pyrrole skeleton, an imidazolium cation, a tetrahydropyrimidinium cation, a dihydropyrimidinium cation, and a pyrazonium cation. Examples include a lithium cation, a pyrazolinium cation, a tetraalkylammonium cation, a trialkylsulfonium cation, and a tetraalkylphosphonium cation.
Among the cation components, organic cations are preferred, and nitrogen-containing organic cations are particularly preferred in terms of compatibility with the resin, and tetraalkylammonium cations, pyridinium cations, and imidazolium cations are preferred in terms of compatibility with the acrylic resin (A). preferable.

Examples of the anion component include Cl ⁻ , Br ⁻ , I ⁻ , AlCl ₄ ⁻ , Al ₂ Cl ₇ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , ClO ₄ ⁻ , NO ₃ ⁻ , CH ₃ COO ⁻ , and CF ₃ COO. _{^{-, CH 3 SO 3 -,}} CF 3 SO 3 -, (CF 3 SO 2) 3 C -, AsF 6 -, SbF 6 -, NbF 6 -, TaF 6 -, (C 2 O 4) 2 B -, _{^{SCN -, (CN) 2 N}} -, C 4 F 9 SO 3 -, C 3 F 7 COO -, (CF 3 SO 2) (CF 3 CO) N -, - O 3 S (CF 2) 3 SO 3 ^And those represented by the following general formulas (1) to (4) are used.
_{(1) :( C n F 2n} + 1 SO 2) 2 N - ( where, n is an integer of from 1 to 10),
(2): CF ₂ (C _m F _2m SO ₂ ) ₂ N ⁻ (where m is an integer of 1 to 10),
(3): O ₃ S (CF ₂ ) ₁ SO ₃ ⁻ (where 1 is an integer of 1 to 10),
_{(4) :( C p F 2p} + 1 SO 2) N - (C q F 2q + 1 SO 2), ( where, p, q is an integer of from 1 to 10)
Among these, anions containing a fluorine atom are particularly preferable, and furthermore, a fluorine-containing sulfonium anion, a fluorine-containing imide anion, and a fluorine-containing sulfonylimide anion are preferred in terms of antistatic performance and durability, and compatibility with the acrylic resin (A). Is preferred.

  The ionic compound (B) of the present invention is preferably a nitrogen-containing onium salt from the viewpoint of compatibility with the acrylic resin (A), and preferably an alkali metal salt from the viewpoint of excellent heat resistance. The cation component and the anion component constituting the salt are appropriately selected from the combination of the cation component and the anion component.

Examples of the nitrogen-containing onium salt include tetrabutylammonium N, N-bis (trifluoromethanesulfonyl) imide (melting point: about 95 ° C.) and tetraethylammonium N, N-bis (trifluoromethanesulfonyl) imide (melting point: about 110 ° C.) , 1-octyl-3-methylpyridinium bisoxalatoborate (melting point about 55 ° C), 1-octyl-3-methylnonafluorobutanesulfonate (melting point 40.9 ° C), 1-octylpyridinium hexafluorophosphate (melting point 67. 9 ° C.).
Preferred examples of the alkali metal salt include lithium N, N-bis (trifluoromethanesulfonyl) imide (melting point 235 ° C.), lithium trifluoromethanesulfonate (melting point 423 ° C.), and the like.

  From the viewpoint of the balance between antistatic performance and durability, an ionic compound in which the anionic component of the ionic compound (B) is a fluorine-containing anion is preferable, and lithium trifluoromethanesulfonate (manufactured by Tokyo Chemical Industry Co., Ltd.) is particularly preferable. And lithium N, N-bis (trifluoromethanesulfonyl) imide (manufactured by Sanko Chemical Co., Ltd.) is preferably used.

  The ionic compound (B) has a melting point of 30 ° C. or higher, more preferably 35 ° C. to 550 ° C., particularly preferably 40 ° C. to 500 ° C., and still more preferably 50 ° C. to 450 ° C. When the melting point is within such a range, the restriction of the molecular chain of the acrylic polymer by the macromonomer (a1) at high temperatures is not easily reduced, and the durability is improved.

The content of the ionic compound (B) is 3 to 20 parts by weight, particularly preferably 4 to 15 parts by weight, more preferably 5 to 12 parts by weight based on 100 parts by weight of the acrylic resin (A). is there.
If the content of the ionic compound (B) is too small, the antistatic performance is lowered, and malfunction of the touch panel due to static electricity and display unevenness of the liquid crystal cell are easily caused. If too large, the pressure-sensitive adhesive layer is plasticized, Bleeding or the like results in a decrease in durability.

<Crosslinking agent (C)>
The pressure-sensitive adhesive composition of the present invention preferably contains a crosslinking agent (C) in addition to the acrylic resin (A) and the ionic compound (B).
The crosslinking agent (C) is preferable in terms of improving the adhesion to the substrate and improving the durability of the pressure-sensitive adhesive.

The cross-linking agent (C) reacts with a functional group in the acrylic resin (A) to form a cross-linked structure. For example, an isocyanate-based cross-linking agent, an epoxy-based cross-linking agent, an aziridine-based cross-linking agent, and melamine Crosslinking agents, aldehyde crosslinking agents, amine crosslinking agents, metal chelate crosslinking agents, and the like. Among these, it is preferable to use an isocyanate-based cross-linking agent in terms of improving the adhesion to the base material and excellent in reactivity with the acrylic resin (A).
The crosslinking agent (C) may be used alone or in combination of two or more.

  As the isocyanate-based crosslinking agent, for example, 2,4-tolylene diisocyanate, a tolylene diisocyanate-based crosslinking agent such as 2,6-tolylene diisocyanate, a xylylene diisocyanate-based crosslinking agent such as 1,3-xylylene diisocyanate, Aromatic diisocyanate crosslinking agents such as diphenylmethane crosslinking agents such as diphenylmethane-4,4-diisocyanate, naphthalenediisocyanate crosslinking agents such as 1,5-naphthalenediisocyanate; isophorone diisocyanate, 1,4-cyclohexane diisocyanate, 4,4 '-Dicyclohexylmethane diisocyanate, methylcyclohexane diisocyanate, isopropylidene dicyclohexyl-4,4'-diisocyanate, 1,3-diisocyanatomethylcyclohexane, nor Alicyclic isocyanate-based cross-linking agents such as lunan diisocyanate; aliphatic isocyanate-based cross-linking agents such as hexamethylene diisocyanate and trimethylhexamethylene diisocyanate; and adducts, burettes, isocyanurates, and the like of the above isocyanate compounds. .

  Among these isocyanate-based cross-linking agents, tolylene diisocyanate-based cross-linking agents are preferred in terms of pot life and durability, and xylylene diisocyanate-based cross-linking agents or isocyanurate skeleton-containing isocyanate-based cross-linking agents are preferable in terms of shortening aging time. Ring-free isocyanate-based crosslinking agents are preferred in view of yellowing resistance. Among these, specifically, tolylene diisocyanate, xylylene diisocyanate, an adduct of hexamethylene diisocyanate and trimethylolpropane, and a nurate are preferable because they have excellent balance of durability, pot life, and crosslinking speed. .

  Examples of the epoxy crosslinking agent include bisphenol A / epichlorohydrin type epoxy resin, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, and 1,6-hexanediol diglycidyl ether. And trimethylolpropane triglycidyl ether, sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl erythritol, diglycerol polyglycidyl ether and the like.

  Examples of the aziridine-based crosslinking agent include, for example, tetramethylolmethane-tri-β-aziridinylpropionate, trimethylolpropane-tri-β-aziridinylpropionate, N, N′-diphenylmethane-4,4 '-Bis (1-aziridinecarboxamide), N, N'-hexamethylene-1,6-bis (1-aziridinecarboxamide) and the like.

  Examples of the melamine-based crosslinking agent include hexamethoxymethylmelamine, hexaethoxymethylmelamine, hexapropoxymethylmelamine, hexaptoxymethylmelamine, hexapentyloxymethylmelamine, hexahexyloxymethylmelamine, and melamine resin. .

  Examples of the aldehyde-based crosslinking agent include glyoxal, malondialdehyde, succindialdehyde, maleic dialdehyde, glutardialdehyde, formaldehyde, acetaldehyde, benzaldehyde and the like.

  Examples of the amine-based crosslinking agent include hexamethylene diamine, triethyl diamine, polyethylene imine, hexamethylene tetraamine, diethylene triamine, triethyl tetraamine, isophorone diamine, amino resin, polyamide and the like.

  Examples of the metal chelate crosslinking agent include, for example, acetylacetone and acetoacetyl ester coordination compounds of polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, panadium, chromium, and zirconium. No.

  When such a cross-linking agent (C) is used, its content is preferably 0.005 to 30 parts by weight, particularly preferably 0.01 to 100 parts by weight of the acrylic resin (A). 10 to 10 parts by weight, more preferably 0.03 to 5 parts by weight, particularly preferably 0.05 to 3 parts by weight. If the content is too small, the durability tends to decrease. If the content is too large, the stress relaxation property decreases, and the substrate tends to be warped or aging for a long time is required.

  Further, it is preferable that the pressure-sensitive adhesive composition of the present invention further contains a silane coupling agent (D) as long as the effects of the present invention are not impaired.

<Silane coupling agent (D)>
The silane coupling agent (D) is an organosilicon compound having at least one reactive functional group and at least one alkoxy group bonded to a silicon atom in the structure. Is preferably contained in the agent composition.

  Examples of the reactive functional group in the silane coupling agent (D) include an epoxy group, a (meth) acryloyl group, a mercapto group, a hydroxyl group, a carboxy group, an amino group, an amide group, and an isocyanate group. Among them, an epoxy group and a mercapto group are preferable from the viewpoint of excellent durability and reworkability.

  The content ratio of the reactive functional group in the silane coupling agent (D) is preferably 3,000 g / mol or less, preferably 1,500 g / mol or less, and more preferably 800 g / mol or less. Within the above range, the balance between durability and reworkability tends to be excellent.

  The alkoxy group in the silane coupling agent (D) preferably contains an alkoxy group having 1 to 8 carbon atoms from the viewpoint of durability and storage stability, and particularly preferably contains a methoxy group and an ethoxy group. preferable.

  The silane coupling agent (D) may have a reactive functional group and an organic functional group other than an alkoxy group bonded to a silicon atom, such as an alkyl group and a phenyl group.

  The silane coupling agent (D) preferably has a weight average molecular weight of 1,000 or more from the viewpoint of reworkability and durability, and more preferably has a weight average molecular weight of 2,300 to 30,000, particularly 3,000 to 20,000. Are preferred. When the weight average molecular weight is in the above range, the balance between reworkability and durability tends to be excellent.

The above weight average molecular weight is a weight average molecular weight in terms of standard polystyrene molecular weight, and can be measured by the following method.
・ Apparatus: Gel permeation chromatograph ・ Detector: Differential refractive index detector RI (manufactured by Tosoh Corporation, Model RI-8020, sensitivity 32)
-Column: TSKgel guardcolumn HHR-H (1) (Tosoh Corporation, φ6 mm x 4 cm), TSKgel GMHHR-N (2) (Tosoh Corporation, φ7.8 mm x 30 cm)
-Solvent: tetrahydrofuran (THF)
-Column temperature: 23 ° C
・ Flow rate: 1.0 mL / min

The silane coupling agent (D) is an oligomeric organosilicon compound (organosiloxane compound) such as a dimer, trimer or the like obtained by partially hydrolyzing and polycondensing the organosilicon compound. For example, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, and a part of a mercapto group-containing silane compound such as 3-mercaptopropyldimethoxymethylsilane are hydrolyzed and polycondensed. Mercapto group-containing oligomer type silane coupling agent or co-condensation product of the above mercapto group-containing silane compound and alkyl group-containing silane compound such as methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane Oligomers containing mercapto groups Run coupling agent: γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, methyltri (glycidyl) Epoxy groups obtained by partially hydrolyzing and polycondensing some epoxide-containing silane compounds such as silane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, and β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane -Containing oligomer type silane coupling agent; epoxy which is a co-condensate of the above epoxy group-containing silane compound and an alkyl group-containing silane compound such as methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane, etc. Group containing Goma-type silane coupling agent; these epoxy group-containing oligomeric silane coupling agent partially ether-modified epoxy group-containing oligomeric silane coupling agent, and the like.
These may be used alone or in combination of two or more.

  The oligomer type silane coupling agent preferably has an alkoxy group content of 1 to 60% by weight, particularly preferably 3 to 50% by weight, and more preferably 5 to 25% by weight. It is preferable because it has an excellent balance of properties.

  Specific examples of the oligomer-type silane coupling agent include commercially available products of epoxy group-containing silane coupling agents “KBM-403”, “X-41-1053”, and “X-” manufactured by Shin-Etsu Chemical Co., Ltd. 41-1059A "," X-24-9590 "," KBM-803 "," X-41-1805 "," X-41-1810 "," X-41-1818 "and the like.

When the silane coupling agent (D) is used, the content thereof is preferably 0.001 to 3 parts by weight, particularly preferably 0.005 parts by weight, based on 100 parts by weight of the acrylic resin (A). To 1 part by weight, more preferably 0.01 to 0.5 part by weight, particularly preferably 0.015 to 0.3 part by weight.
If the content is too small, the reworkability tends to decrease, and if too large, the silane coupling agent (D) bleeds and the durability tends to decrease.

<Other optional ingredients>
Further, in the pressure-sensitive adhesive composition of the present invention, as long as the effects of the present invention are not impaired, as other optional components, a resin component, an acrylic monomer, a polymerization inhibitor, an antioxidant, a corrosion inhibitor, a crosslinking accelerator, Various additives such as a radical generator, a peroxide, a radical scavenger, an ultraviolet absorber, an antioxidant, a plasticizer, a pigment, a stabilizer, a filler, metal and resin particles, and the like can be blended. In addition to the above, the adhesive composition may contain a small amount of impurities or the like contained in the raw materials for producing the components of the pressure-sensitive adhesive composition.

  When the above-mentioned other optional components are used, the content is preferably 5 parts by weight or less, particularly preferably 1 part by weight or less, more preferably 0.1 part by weight, based on 100 parts by weight of the acrylic resin (A). 5 parts by weight or less. If the content is too large, the compatibility with the acrylic resin (A) decreases, and the durability tends to decrease.

  Thus, by mixing the acrylic resin (A) and the ionic compound (B), and if necessary, the crosslinking agent (C), the silane coupling agent (D), and other optional components, the pressure-sensitive adhesive of the present invention is obtained. A composition can be obtained.

  The mixing method is not particularly limited, and various methods such as a method of mixing each component at a time or a method of mixing arbitrary components and then mixing the remaining components at once or sequentially are adopted. can do.

The pressure-sensitive adhesive composition of the present invention can be made into a pressure-sensitive adhesive by curing (crosslinking), and further, by laminating a pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive on an optical member (optical laminate), An optical member with an adhesive layer can be obtained.
It is preferable that the optical member with the pressure-sensitive adhesive layer is further provided with a release sheet on the surface of the pressure-sensitive adhesive layer opposite to the surface of the optical member.

As a method of manufacturing the optical member with the pressure-sensitive adhesive layer,
[1] A method in which a pressure-sensitive adhesive composition is applied on an optical member, dried, and then a release sheet is bonded thereto, and a treatment is performed by aging at least one of normal temperature (23 ° C.) and a heated state.
[2] a method of applying the pressure-sensitive adhesive composition on a release sheet, drying and then bonding an optical member, and performing aging treatment in at least one of a normal temperature and a heated state;
And the like. Among them, the method of aging at room temperature by the method [2] is preferable in that the optical member is not damaged and the adhesion to the optical member is excellent.
In the above, the optical member is particularly effective when it is a polarizing plate, but the above method can also be used when an adhesive layer is formed on an adherend other than the optical member.

  Such aging treatment is performed as a reaction time of the chemical crosslinking of the pressure-sensitive adhesive to balance the pressure-sensitive adhesive properties. As aging conditions, the temperature is 20 to 70 ° C., and the time is usually 1 to 30 days. Specifically, for example, the reaction may be performed at 23 ° C. for 1 to 20 days, at 23 ° C. for 3 to 10 days, and at 40 ° C. for 1 to 7 days.

  In applying the pressure-sensitive adhesive composition, it is preferable to dilute the pressure-sensitive adhesive composition in a solvent, and to apply the diluted pressure-sensitive adhesive composition. The dilution concentration is preferably a solid concentration of 5 to 60% by weight, particularly preferably. It is 10 to 30% by weight.

The solvent is not particularly limited as long as it dissolves the pressure-sensitive adhesive composition.Examples include methyl acetate, ethyl acetate, methyl acetoacetate, ester solvents such as ethyl acetoacetate, acetone, methyl ethyl ketone, Ketone solvents such as methyl isobutyl ketone, aromatic solvents such as toluene and xylene, and alcohol solvents such as methanol, ethanol and propyl alcohol can be used. Among them, ethyl acetate and methyl ethyl ketone are preferably used from the viewpoint of solubility, drying property, price and the like.
These can be used alone or in combination of two or more.

  The application of the pressure-sensitive adhesive composition is performed by a conventional method such as roll coating, die coating, gravure coating, comma coating, and screen printing.

  The gel fraction of the pressure-sensitive adhesive layer produced by the above method is preferably from 30 to 98% by weight, particularly preferably from 35 to 95% by weight, more preferably from 50 to 50% by weight, from the viewpoint of durability performance and suppression of a decrease in polarization degree. ~ 90% by weight. If the gel fraction is too low, the pressure-sensitive adhesive layer tends to foam in a high-temperature environment, and if it is too high, there is a tendency for floating and peeling to occur.

  The gel fraction is a measure of the degree of crosslinking (degree of curing), and is calculated, for example, by the following method. That is, an adhesive is picked up from an adhesive film in which an adhesive layer is formed on a base material such as an optical member, especially a polarizing plate, and the adhesive is wrapped with a 200-mesh SUS wire mesh, and acetic acid adjusted to 23 ° C. By immersing in ethyl acetate for 24 hours, the weight percentage of the insoluble adhesive component remaining in the wire mesh with respect to the weight of the adhesive before immersion in ethyl acetate is defined as the gel fraction.

  The pressure-sensitive adhesive layer produced by the above method has a favorable tackiness when touched by a finger, and has good wettability when actually affixed to an adherend, and thus tends to increase workability, which is preferable. .

Regarding the electrical properties of the pressure-sensitive adhesive layer obtained by using the pressure-sensitive adhesive composition of the present invention, a low surface resistivity is preferable as a measure against static electricity, more preferably less than 1.0 × 10 ¹⁰ Ω / cm ² , particularly preferably. Is less than 8.0 × 10 ⁹ Ω / cm ² , more preferably less than 5.0 × 10 ⁹ Ω / cm ² , particularly preferably less than 4.0 × 10 ⁹ Ω / cm ² . If the surface resistivity is too high, the pressure-sensitive adhesive is likely to be charged, and display unevenness due to static electricity tends to easily occur when used for liquid crystal display applications.

  In the present invention, the optical member with an adhesive layer, in particular, a polarizing plate with an adhesive layer, directly, or those having a release sheet after peeling off the release sheet, the adhesive layer surface is bonded to a glass substrate, For example, it is provided for a liquid crystal display panel.

  The pressure-sensitive adhesive composition of the present invention is capable of obtaining a pressure-sensitive adhesive that can achieve both high antistatic performance and durability even under a high-temperature environment, and includes a pressure-sensitive adhesive for optical members, particularly a polarizing plate and a glass substrate. It is useful as an adhesive for polarizing plates to be attached.

  Examples of the protective film constituting the polarizing plate include triacetyl cellulose-based films, acrylic films, polyethylene films, polypropylene films, cycloolefin films, and the like.The present invention relates to a polarizing plate using any of the protective films. Although it is preferably used, a polarizing plate on which a cycloolefin-based film is laminated is particularly preferable because the effect of the present invention is easily obtained.

  In addition, by using the above adhesive, an image display device such as a liquid crystal display device can be manufactured by bonding a polarizing plate and a liquid crystal cell, and the obtained image display device can be manufactured with high accuracy and have high durability. Become better.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist of the present invention. In the examples, “parts” and “%” mean on a weight basis.

First, various acrylic resins (A) were prepared as described below, and other raw materials for the pressure-sensitive adhesive composition were prepared. The acid value, weight average molecular weight, dispersity, and glass transition temperature of the acrylic resin (A) were measured according to the above-described methods.
In addition, about the measurement of a viscosity, it is the value measured at 25 degreeC using the B-type viscometer.

<Acrylic resin (A)>
The following materials were prepared as raw materials of the acrylic resin (A) (see Table 1).

<Macromonomer (a1)>
The following were prepared as the macromonomer (a1).
When calculating the glass transition temperature, the following values were used for the glass transition temperature when each monomer was a homopolymer.
・ Methyl methacrylate (MMA): 105 ° C
・ N-butyl acrylate (BA): -56 ° C
-2-hydroxyethyl methacrylate (HEMA): 55 ° C

(Macromonomer 1):
Acrylic macromonomer containing a hydroxyl group in the side chain, which is a polymer of methyl methacrylate (MMA) and 2-hydroxyethyl methacrylate (HEMA) (MMA: HEMA (weight ratio) = 75.5: 24, manufactured by Mitsubishi Chemical Corporation) 0.5, number average molecular weight 5,700, dispersity 1.6, calculated glass transition temperature 91 ° C)

(Macromonomer 2):
Acrylic macromonomer containing polybutyl acrylate (PBA) as a main component (manufactured by Kaneka Corporation, PBA = 100%, number average molecular weight 7,970, dispersity 1.2, calculated glass transition temperature -56 ° C.)

(Macromonomer 3):
Acrylic macromonomer containing polymethyl methacrylate (PMMA) as the main component (manufactured by Mitsubishi Chemical Corporation, PMMA = 100%, number average molecular weight 3,700, dispersity 1.7, calculated glass transition temperature 105 ° C.)

[Production of acrylic resin (A-1)]
1 part of the prepared macromonomer 1 (a1), 90.3 parts of n-butyl acrylate (a2) were placed in a four-neck round bottom flask equipped with a reflux condenser, a stirrer, a nitrogen gas inlet, and a thermometer. 8 parts of 2-hydroxyethyl acrylate (a3), 0.7 parts of acrylic acid (a3), 53 parts of ethyl acetate, 42 parts of acetone, and 0.013 part of azobisisobutyronitrile (AIBN) as a polymerization initiator were charged. The reaction was started by raising the internal temperature to the boiling point. Next, 30 parts of an ethyl acetate solution containing 0.04% of AIBN was added dropwise, and the mixture was allowed to react at reflux temperature for 3.25 hours. Then, the mixture was diluted with ethyl acetate to obtain an acrylic resin (A-1) solution (solid content of 26. 2%, viscosity 4,500 mPa · s / 25 ° C., acrylic resin (A-1): acid value 0.55 mgKOH / g, weight average molecular weight 1,110,000, dispersity 4.0, calculated glass transition temperature −51.6 ° C).

[Production of acrylic resin (A-2)]
1 part of the prepared macromonomer 2 (a1), 90.3 parts of n-butyl acrylate (a2) were placed in a four-neck round bottom flask equipped with a reflux condenser, a stirrer, a nitrogen gas inlet, and a thermometer. 8 parts of 2-hydroxyethyl acrylate (a3), 0.7 parts of acrylic acid (a3), 53 parts of ethyl acetate, 42 parts of acetone, and 0.013 part of azobisisobutyronitrile (AIBN) as a polymerization initiator were charged. The reaction was started by raising the internal temperature to the boiling point. Next, 30 parts of an ethyl acetate solution containing 0.04% of AIBN was dropped and reacted at a reflux temperature for 3.25 hours, and then diluted with ethyl acetate to dilute with an acrylic resin (A-2) solution (solid content of 26. 4%, viscosity 9,400 mPa · s / 25 ° C., acrylic resin (A-2): acid value 0.55 mgKOH / g, weight average molecular weight 1.3 million, dispersity 3.3, calculated glass transition temperature −52.5 ° C).

[Production of acrylic resin (A-3)]
In a four-neck round bottom flask equipped with a reflux condenser, a stirrer, a nitrogen gas inlet, and a thermometer, 1 part of the prepared macromonomer 3 (a1), 90.3 parts of n-butyl acrylate (a2), 8 parts of 2-hydroxyethyl acrylate (a3), 0.7 parts of acrylic acid (a3), 53 parts of ethyl acetate, 42 parts of acetone, and 0.013 part of azobisisobutyronitrile (AIBN) as a polymerization initiator were charged. The reaction was started by raising the internal temperature to the boiling point. Next, 30 parts of an ethyl acetate solution containing 0.04% of AIBN was added dropwise, and the mixture was allowed to react at reflux temperature for 3.25 hours. The mixture was diluted with ethyl acetate and diluted with an acrylic resin (A-3) solution (solid content 26. 5%, viscosity 2,385 mPa · s / 25 ° C., acrylic resin (A-3): acid value 0.55 mgKOH / g, weight average molecular weight 1,030,000, dispersity 3.6, calculated glass transition temperature −51.6 ° C).

The following monomers were used as the monomers used above.
-N-butyl acrylate (BA) (manufactured by Mitsubishi Chemical Corporation, glass transition temperature -56 ° C)
-2-hydroxyethyl acrylate (HEA) (manufactured by Osaka Organic Chemical Company, glass transition temperature -15 ° C)
Acrylic acid (AAc) (manufactured by Mitsubishi Chemical Corporation, glass transition temperature 106 ° C)
The above glass transition temperature is the glass transition temperature of the homopolymer of each monomer.

<Ionic compound (B)>
The following were prepared as the ionic compound (B).
(B-1): lithium trifluoromethanesulfonate (manufactured by Tokyo Chemical Industry Co., Ltd.) (melting point: 423 ° C.)
(B-2): 56% solution of lithium N, N-bis (trifluoromethanesulfonyl) imide [solvent: tetraethylene glycol dimethyl ether (manufactured by Sanko Chemical Co., Sanconol TGR)] (melting point: 235 ° C.)
(B′-1): tributylmethylammonium N, N-bis (trifluoromethanesulfonyl) imide (FC-4400, manufactured by 3M) (melting point: 27.5 ° C.)

<Crosslinking agent (C)>
The following were prepared as a crosslinking agent (C).
(C-1): Adduct of tolylene diisocyanate and trimethylolpropane (Coronate L55E, manufactured by Tosoh Corporation)

<Silane coupling agent (D)>
The following were prepared as a silane coupling agent (D).
In addition, about the kind of the reactive functional group of a silane coupling agent (D), an epoxy equivalent or a mercapto equivalent, the kind of the contained alkoxy group, and the alkoxy group content, the catalog value was employ | adopted unless there was a notice. In addition, the weight average molecular weight and the degree of dispersion were measured according to the methods described above.

(D-1): 1: 1 (weight ratio) mixture of "X-24-9590" and "X-41-1059A". "X-24-9590": manufactured by Shin-Etsu Chemical Co., Ltd., containing reactive functional group : Epoxy group, reactive functional group equivalent: 592 g / mol, alkoxy group content: methoxy group, alkoxy group content: 9.5%, weight average molecular weight: 13,700, dispersity: 3.44
-"X-41-1059A": manufactured by Shin-Etsu Chemical Co., Ltd., containing reactive functional group: epoxy group, reactive functional group equivalent: 350 g / mol, containing alkoxy group: methoxy group and ethoxy group, and alkoxy group content: 42 %, Weight average molecular weight: 2,270, dispersity: 1.86

<Examples 1-3, Comparative Examples 1-3>
The above components were blended as shown in Table 2 below, and the solid content concentration was adjusted to 15% with ethyl acetate to obtain a pressure-sensitive adhesive composition.

  Using the pressure-sensitive adhesive composition obtained above, a sample for evaluation was prepared as described below, and the following performance was evaluated. The evaluation results are shown in Table 2 below.

[Preparation of polarizing plate [I] with adhesive layer]
The obtained pressure-sensitive adhesive composition was applied to a release sheet (Therapy WZ, manufactured by Toray Industries, Inc.) having a thickness of 38 μm so that the thickness after drying was 20 μm, and dried at 100 ° C. for 3 minutes. (TAC) -based film laminated on both sides of one side of the TAC-based film surface of the polarizing plate, the adhesive layer side opposite to the release sheet is bonded, and aged for 7 days in an environment of 23 ° C. × 50% RH. A polarizing plate [I] with an agent layer was obtained [Layer composition: release sheet / adhesive layer / TAC film 1 / polarizer / TAC film 2].
The TAC film is a triacetyl cellulose film, and the thickness of the TAC film 1 is 40 μm and the thickness of the TAC film 2 is 40 μm.
The following evaluation was performed using the polarizing plate with an adhesive layer [I].

<Durability: Heat resistance test>
The obtained polarizing plate with an adhesive layer [I] was cut into a size of 165 mm × 95 mm, the release sheet was peeled off, and the surface of the adhesive layer was pressed against non-alkali glass (Corning Co., Eagle XG, thickness 1.1 mm), 2 kg. After two reciprocations with a roller and bonding, autoclave treatment (0.5 MPa × 50 ° C. × 20 minutes) was performed to prepare a sample for durability evaluation.
With respect to the obtained sample, the following evaluation was performed on the polarizing plate after exposure under the condition of heat resistance (105 ° C. × 100 hours).
(Evaluation criteria)
・ ・ ・: Foaming was not observed on the entire surface of the polarizing plate or no floating was observed at the end portion, or a slight floating was observed at the corner.
Δ: Slight floating is observed on the edge of the polarizing plate.
C: Foaming on the entire surface of the polarizing plate or floating of 1 mm or more on the edge is observed.

<Gel fraction>
The release sheet of the obtained polarizing plate with an adhesive layer [I] was peeled off, the adhesive was picked from the surface of the adhesive layer, wrapped with a 200 mesh wire mesh made of SUS, and then placed in ethyl acetate adjusted to 23 ° C. for 24 hours. After immersion, the weight percentage of the undissolved pressure-sensitive adhesive component remaining in the wire mesh with respect to the weight of the pressure-sensitive adhesive before immersion in ethyl acetate was defined as a gel fraction (%).

<Antistatic performance: surface resistivity>
After the polarizing plate with the pressure-sensitive adhesive layer [I] is allowed to stand in an atmosphere of 23 ° C. × 50% RH for 24 hours, the release sheet of the pressure-sensitive adhesive layer is removed, and a surface resistivity measurement device (manufactured by Mitsubishi Chemical Analytech, Inc. The surface resistivity (Ω / cm ² ) of the pressure-sensitive adhesive layer was measured using Hiresta-UP MCP-HT450).

From the above results, it is a pressure-sensitive adhesive composition containing an acrylic resin (A) containing a structural part derived from the macromonomer (a1) and an ionic compound (B) having a melting point of 30 ° C. or more, In Examples 1 to 3, which are pressure-sensitive adhesive compositions containing a large amount of the ionic compound (B) with respect to A), a pressure-sensitive adhesive that can achieve both high durability and antistatic performance in a high-temperature environment is used. It can be seen that they are formed.
On the other hand, in Comparative Examples 1 to 3 in which an ionic compound having a low melting point was contained, it can be seen that all of the adhesives were inferior in durability.
Therefore, it can be seen that the pressure-sensitive adhesive obtained by using the pressure-sensitive adhesive composition of the present invention can achieve both high antistatic performance and high durability even under a high-temperature environment.

  And since the polarizing plate with a pressure-sensitive adhesive layer obtained by using the pressure-sensitive adhesive composition which is an example product of the present invention has both high durability and antistatic performance, the polarizing plate is provided via the pressure-sensitive adhesive layer. It is expected that an image display device obtained by bonding an image display member such as a liquid crystal cell with a liquid crystal cell will have excellent quality.

  When the pressure-sensitive adhesive composition of the present invention is used as a pressure-sensitive adhesive for bonding a polarizing plate (protective film) to a liquid crystal cell (glass plate) or a metal surface such as a conductive layer during the production of a liquid crystal display device, Excellent durability even under high temperature environment, and excellent antistatic performance, adhesive for optical members for bonding the display and the optical components constituting it, especially the polarizing plate and the glass substrate of the liquid crystal cell, It is useful as a pressure-sensitive adhesive for a polarizing plate for attaching a substrate or the like having a conductive layer.

Claims (13)

  A pressure-sensitive adhesive composition containing an acrylic resin (A) containing a structural site derived from a macromonomer (a1) and an ionic compound (B), wherein an ionic resin is used for 100 parts by weight of the acrylic resin (A). A pressure-sensitive adhesive composition comprising 3 to 20 parts by weight of a compound (B), and wherein the ionic compound (B) is an ionic compound having a melting point of 30 ° C. or higher.   The pressure-sensitive adhesive composition according to claim 1, wherein the macromonomer (a1) is an acrylic macromonomer having a structure derived from an alkyl (meth) acrylate and a polar group-containing (meth) acrylate.   3. The pressure-sensitive adhesive composition according to claim 1, wherein the number average molecular weight of the macromonomer (a1) is 1,000 to 50,000.   The content of the macromonomer (a1) is 0.1 to 10% by weight with respect to a polymerization component constituting the acrylic resin (A), The macromonomer (a1) is in any one of Claims 1-3 characterized by the above-mentioned. Pressure-sensitive adhesive composition.   The pressure-sensitive adhesive according to any one of claims 1 to 4, wherein the acrylic resin (A) is an acrylic resin obtained by polymerizing a polymerization component containing a polar group-containing monomer (a3). Composition.   The pressure-sensitive adhesive composition according to any one of claims 1 to 5, wherein the acrylic resin (A) has an acid value of 30 mgKOH / g or less.   The pressure-sensitive adhesive composition according to any one of claims 1 to 6, wherein the ionic compound (B) is at least one of a nitrogen-containing onium salt and an alkali metal salt.   The pressure-sensitive adhesive composition according to any one of claims 1 to 7, further comprising a crosslinking agent (C).   The pressure-sensitive adhesive composition according to any one of claims 1 to 8, further comprising a silane coupling agent (D).   A pressure-sensitive adhesive, wherein the pressure-sensitive adhesive composition according to any one of claims 1 to 9 is cross-linked by a cross-linking agent (C). Adhesive of claim 10, wherein the surface resistivity of the adhesive layer is less than ^{1.0 × 10 10 Ω / cm 2} .   A pressure-sensitive adhesive for a polarizing plate, comprising the pressure-sensitive adhesive according to claim 10.   An image display device, comprising: a polarizing plate and an image display member bonded together with the adhesive according to claim 10.