JP2019214707A - Adhesive composition, and adhesive, adhesive for polarizing plate, and image display device including the same - Google Patents

Abstract

To provide an adhesive composition, wherein, in the production of a liquid crystal display device, the adhesive composition is used as an adhesive for bonding a polarizing plate (protection film) to a liquid crystal cell (glass plate), it can achieve both of high antistatic performance and durability even under a severe high-temperature environment or under a high-temperature and high-humidity environment.SOLUTION: An adhesive composition contains an acrylic resin (A) and an ionic compound (B), the acrylic resin (A) being an acrylic resin obtained by polymerization of a polymerization component containing a macromonomer (a1) having a polar group in a side chain.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 high antistatic performance even under a high-temperature environment or a high-temperature and high-humidity environment. The present invention relates to a pressure-sensitive adhesive composition that forms a pressure-sensitive adhesive that can achieve both durability, a pressure-sensitive adhesive using the same, a pressure-sensitive adhesive for a polarizing plate, and an image display device.

  Conventionally, a polarizing plate made of a polyvinyl alcohol-based film or the like having a polarizing property and the like, both surfaces of which are covered with a protective film, is laminated on the surface of a liquid crystal cell having a liquid crystal component oriented 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) includes, for example, a polarizing plate floating from the liquid crystal cell (glass plate) under a high temperature environment or a high temperature and high humidity environment. There is a demand for durability that does not peel or peel off.

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

  For example, it has been proposed to mix an ionic compound for the purpose of imparting antistatic performance to a pressure-sensitive adhesive (for example, see Patent Document 1).

  Further, it has been proposed to include an ionic compound in the pressure-sensitive adhesive layer for the purpose of preventing a malfunction even in a display mounted with a touch panel (for example, see Patent Document 2). In particular, in a display for a vehicle, static electricity is easily generated by operating a steering wheel or the like, so that a higher antistatic performance is required for the adhesive layer.

JP 2009-79205 A JP 2017-67942 A

  However, in the techniques disclosed in Patent Documents 1 and 2, in order to further improve the antistatic performance, it is necessary to contain a large amount of an ionic compound. It is not yet satisfactory in terms of durability under a low temperature or high temperature and high humidity environment, and there has been a problem that the adhesive film may float or peel off.

  Therefore, in the present invention, in such a background, for example, when a metal such as a glass plate or a conductive layer used for a liquid crystal cell is used as an adherend, a high charge is obtained even under a high temperature environment or a high temperature and high humidity 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, as a result of intensive studies in view of such circumstances, the present inventors have found that an adhesive composition containing an acrylic resin (A) and an ionic compound (B) usually contains an ionic compound (B). However, the use of a macromonomer (a1) having a polar group in the side chain as a polymerization component of the acrylic resin (A) can reduce the durability of the acrylic resin (A). The polar group located in the chain can efficiently bind the ionic compound (B), suppress the bleeding of the ionic compound (B) and the plasticization of the pressure-sensitive adhesive at the interface of the adherend, and prevent floating and peeling. It has been found that an adhesive that can achieve both high antistatic performance and high durability can be obtained, and the present invention has been completed.

  That is, the gist of the present invention is a pressure-sensitive adhesive composition containing an acrylic resin (A) and an ionic compound (B), wherein the acrylic resin (A) has a macromonomer having a polar group in a side chain ( The present invention relates to a pressure-sensitive adhesive composition which is an acrylic resin obtained by polymerizing a polymerization component containing a1).

  Furthermore, the present invention relates to an adhesive obtained by crosslinking the above-mentioned adhesive composition with a crosslinking agent (C), an adhesive for a polarizing plate, and an image display device.

  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 under a high temperature environment or a high temperature and high humidity environment. And the adhesive composition of this invention can obtain the adhesive suitable for various uses, especially a polarizing plate.

  When the macromonomer (a1) having a polar group in the side chain is a macromonomer having a hydroxyl group in the side chain, an adhesive having more excellent durability can be obtained.

  Furthermore, when the macromonomer (a1) having a polar group in the side chain is an acrylic macromonomer having a structure derived from an alkyl (meth) acrylate and a hydroxyl group-containing (meth) acrylate, it has excellent compatibility with other monomers. , Because copolymerization is facilitated.

  When the content of the macromonomer (a1) having a polar group in the side chain is 0.1 to 30% by weight with respect to the polymerization component constituting the acrylic resin (A), the antistatic performance and the durability are improved. Excellent balance of the pressure-sensitive adhesive can be obtained.

  Further, when the acrylic resin (A) is an acrylic resin obtained by polymerizing a polymerization component further containing the polar group-containing monomer (a3), a pressure-sensitive adhesive having more excellent durability can be obtained.

  Further, when the content ratio of the polar group-containing monomer (a3) is 0.01 to 30% by weight with respect to the polymerization component constituting the acrylic resin (A), a pressure-sensitive adhesive having even more excellent durability can be obtained. Become like

  When the content of the ionic compound (B) is 1 to 30 parts by weight with respect to 100 parts by weight of the acrylic resin (A), a pressure-sensitive adhesive which is more excellent in balance between antistatic performance and durability can be obtained. Will be able to

  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.

  In particular, when the pressure-sensitive adhesive 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 in the production of a liquid crystal display device, It has good antistatic performance and high durability and is very useful as an adhesive for polarizing plates and conductive layers.

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, respectively. . 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) obtained by polymerizing a polymerization component containing a macromonomer (a1) having a polar group in a side chain, and an ionic compound (B). .

<Acrylic resin (A)>
The acrylic resin (A) used in the present invention is a resin obtained by polymerizing a macromonomer (a1) having a polar group in a side chain as a polymerization component, and having a polar group in the side chain. In addition to the macromonomer (a1), it contains a (meth) acrylic acid alkyl ester (a2), preferably a polar group-containing monomer (a3) (excluding the macromonomer (a1)), if necessary. And an acrylic resin obtained by polymerizing a polymerization component containing another copolymerizable monomer (a4).

[Macromonomer having polar group in side chain (a1)]
The macromonomer (a1) having a polar group in the side chain refers to a high molecular weight monomer having a polar group in the side chain and having a polymerizable functional group. It is preferable to have a group (hereinafter, “macromonomer (a1) having a polar group in a side chain”) may be abbreviated as “macromonomer (a1)”.

  The polymer chain (main chain) portion constituting the macromonomer (a1) is not particularly limited as long as it has a polar group in a side chain, but is a polymer connected by a carbon-carbon bond. It is preferably a chain, and a macromonomer containing (meth) acrylate as a constitutional unit is preferable in view of compatibility and polymerizability with other copolymer components (a2) to (a4), and in particular, alkyl (meth) acrylate It is preferable to include a structural unit derived from (meth) acrylate selected from methyl (meth) acrylate and butyl (meth) acrylate.

  Examples of the side group polar group constituting the macromonomer (a1) include polar groups such as a hydroxyl group, a carboxy group, and a nitrogen atom. Among these polar groups, the bleeding of the antistatic agent can be suppressed. , A hydroxyl group, an amide group, and a carboxy group are preferable, and a hydroxyl group is preferable in terms of low corrosiveness and excellent reactivity with a crosslinking agent.

  The content ratio of the polar group in the macromonomer (a1) is preferably 0.1 to 50% by weight in the macromonomer (a1) as a monomer unit having a polar group, and more preferably 1 to 40% by weight. It is preferably, especially 3 to 30% by weight. When the content is within the above range, the durability tends to be excellent even when an antistatic agent is used, which is preferable.

  The number average molecular weight (Mn) of the macromonomer (a1) is preferably at least 1,000, more preferably at least 2,000, particularly preferably at least 3,000 in view of mechanical properties and durability of the obtained pressure-sensitive adhesive. And still more preferably 4,000 or more, while 50,000 or less is preferred, more preferably 30,000 or less, and particularly preferably 20,000 or less. When Mn is equal to or more than the lower limit, the degree of freedom of the polar group derived from the macromonomer (a1) as the acrylic resin (A) is increased, and the ionic compound (B) tends to be restrained, which tends to be excellent in durability. . 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 of ACQUITY APC XT 450 and ACQUITY. It is measured by using one APC XT 200 and two ACQUITY APC XT 45 in series.

  The glass transition temperature (Tg) of the macromonomer (a1) is preferably −100 to 150 ° C., more preferably −70 to 130 ° C., and still more preferably −50 to 120 ° C. from the viewpoint of durability. The glass transition temperature (Tg) of the macromonomer (a1) can be calculated from, for example, 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; (Meta) acri Yloxyethyl hexahydrophthalic acid, 2- (meth) acryloyloxypropyl hexahydrophthalic acid, 2- (meth) acryloyloxyethyl phthalic acid, 2- (meth) acryloyloxypropyl phthalic acid, 2- (meth) acryloyloxy Ethyl maleic acid, 2- (meth) acryloyloxypropyl maleic acid, 2- (meth) acryloyloxyethyl succinic acid, 2- (meth) acryloyloxypropyl succinic acid, crotonic acid, fumaric acid, maleic acid, itaconic acid, maleic Carboxy group-containing vinyl monomers such as monomethyl acrylate, monomethyl itaconate; acid anhydride group-containing vinyl monomers such as maleic anhydride and itaconic anhydride; glycidyl (meth) acrylate, glycidyl α-ethyl acrylate; , 4-epoxybutyl (meta ) Epoxy group-containing vinyl monomers such as acrylates; amino group-containing (meth) acrylate vinyl monomers such as dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate; (meth) acrylamide, N Contains amide groups such as -t-butyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, diacetone acrylamide, maleic amide, and maleimide Vinyl monomers such as styrene, α-methylstyrene, vinyltoluene, (meth) acrylonitrile, vinyl chloride, vinyl acetate, and vinyl propionate; divinylbenzene, ethylene glycol di (meth) acrylate, 1,3- Tylene 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.
The raw material monomers can be used alone or in combination of two or more.

  From the viewpoint of having a polar group in the side chain of the macromonomer (a1), the raw material monomers include (meth) acrylate containing a hydroxyl group, vinyl monomer containing a carboxy group, and vinyl monomer containing an acid anhydride group. At least one polar group-containing monomer selected from the group consisting of an amino group-containing (meth) acrylate-based vinyl monomer and an amide group-containing vinyl monomer is used. Among the polar group-containing monomers, Hydroxyl group-containing (meth) acrylates are preferred from the viewpoint of durability.

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

  And, among the above-mentioned raw material monomers, it is preferable to contain a (meth) alkyl acrylate having 1 to 8 carbon atoms and a (meth) acrylate containing a hydroxyl group, and further, methyl (meth) acrylate, butyl (meth) acrylate and 2- (meth) acrylate Hydroxyethyl (meth) acrylate is preferred in terms of compatibility with other copolymerizable components (a2) to (a4) and copolymerizability.

  The content of the macromonomer (a1) is preferably from 0.1 to 30% by weight, particularly preferably from 0.5 to 20% by weight, and more preferably from 0.5 to 20% by weight, based on the polymerization component constituting the acrylic resin (A). Preferably it is 0.8 to 10% by weight. When the content is within the range, the balance between the antistatic performance and the durability is more excellent.

[(Meth) acrylic acid alkyl ester (a2)]
As the (meth) acrylic acid alkyl ester (a2), 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 of 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, 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- (meth) acrylate, in terms of excellent adhesive properties and excellent stability during polymerization. Ethylhexyl (meth) acrylate is preferred, and n-butyl (meth) acrylate is particularly preferred.

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

  Further, from the viewpoint of excellent compatibility with the ionic compound (B), it is preferable to contain methyl (meth) acrylate, ethyl (meth) acrylate, and n-butyl (meth) acrylate, and particularly preferably these Is at least 10% by weight, more preferably at least 30% by weight, particularly preferably from 40 to 99.9% by weight, based on the polymerization component constituting the acrylic resin (A).

[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 ethylenic monomer such as a hydroxyl group-containing monomer, a carboxy group-containing monomer, or a nitrogen atom-containing monomer other than the macromonomer (a1) having a polar group in a side chain. It refers to a saturated monomer, and in the present invention, it preferably contains at least one selected from a hydroxyl group-containing monomer, a carboxy group-containing monomer, and a nitrogen atom-containing monomer. These can be used alone or in combination of two or more.

  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-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.

  Among the above hydroxyl group-containing monomers, primary hydroxyl group-containing monomers are preferable in terms of excellent reactivity with a crosslinking agent, and 2-hydroxyethyl (meth) acrylate is preferable in terms of stability during polymerization, and reactivity with the crosslinking agent is preferred. It is preferable to use 4-hydroxybutyl (meth) acrylate in that aging is short and aging is short. Further, 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate are preferable because they contain few impurities such as di (meth) acrylate and are easy to produce.

  In addition, as the hydroxyl group-containing monomer, it is also preferable to use a monomer having a content of di (meth) acrylate as an impurity of 0.5% by weight or less, particularly preferably 0.2% by weight or less, more preferably 0% by weight or less. 0.1% by weight or less, and specifically, 2-hydroxyethyl acrylate, 4-hydroxybutyl acrylate, and 2-hydroxypropyl acrylate having such an impurity amount are particularly preferable.

  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 terms of wet 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 that they have a 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-mentioned various polar group-containing monomers (a3), it is preferable to have a hydroxyl group-containing monomer from the viewpoint of excellent reactivity with a crosslinking agent.

  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 with respect to the polymerization component constituting the acrylic resin (A). The content is preferably 0.01 to 30% by weight, more preferably 0.1 to 20% by weight, particularly preferably 1 to 15% by weight, particularly preferably 3 to 10% by weight in view of durability and reworkability. .
Among the polar group-containing monomers (a3), 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, from the viewpoint of inhibiting corrosion resistance and 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, methoxypolyethylene glycol (meth) acrylate, octoxypolyethylene glycol-polypropylene glycol-mono (meth) acrylate, lauroxypolyethylene glycol mono (meth) acrylate, stearoxypolyethylene glycol mono (meth) acrylate, etc. 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 are easily adjusted, and the light leakage resistance (light leakage resistance means that when a polarizing plate is used as an adhesive for bonding a liquid crystal cell to a liquid crystal cell, the temperature of a backlight after a high temperature or wet heat test is high. Aromatic ring-containing monomers are preferred, and benzyl (meth) acrylate, phenoxy (meth) ethyl acrylate, and phenoxy diethylene glycol (meth) acrylate are particularly preferred in terms of excellent performance in preventing light leakage.) The alicyclic-containing monomer is preferable in that the refractive index and the birefringence are easily adjusted and the adhesiveness to a low-polar adherend (for example, cycloolefin or the like) is excellent.

  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 containing a compound selected appropriately.

  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.
The amount of the organic solvent to be used is usually 10 to 900 parts by weight based on 100 parts by weight of the polymerization component.

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 4,4'-azobis (4-cyanovaleric acid) and 2,2'-azobis (methylpropionic acid), benzoyl peroxide, lauryl peroxide, di-t-butyl peroxide, Organic peroxides such as cumene hydroperoxide and the like can be mentioned, and they can be appropriately selected and used according to a monomer to be 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 weight average molecular weight of the acrylic resin (A) thus obtained is preferably 200,000 to 3,000,000, particularly preferably 400,000 to 2,000,000, more preferably 600,000 to 1,800,000, and particularly preferably 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 It is measured by using three in series (particle size: 10 μm), and the number average molecular weight can be measured by the same method. The dispersity is determined from the weight average molecular weight and the number average molecular weight.

  The glass transition temperature (Tg) of the acrylic resin (A) is preferably -100 to 10C, particularly preferably -70 to 0C, and more preferably -65 to -20C. 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 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: Homogeneity 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
The glass transition temperature when the homopolymer of the monomer constituting the acrylic resin (A) is used is usually measured by a differential scanning calorimeter (DSC), and is measured according to JIS K7121-1987 and JIS K6240. It can be measured in accordance with a compliant method.

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

  The viscosity of the acrylic resin (A) solution is measured according to the 4.5.3 rotational viscometer method of JIS K5400 (1990).

  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.

As the inorganic cation, an alkali metal cation is preferable in terms of antistatic performance, and a lithium cation is particularly preferable.
As organic cations, pyridinium cation, piperidinium cation, pyrrolidinium cation, cation having a pyrroline skeleton, cation having a pyrrole skeleton, imidazolium cation, tetrahydropyrimidinium cation, dihydropyrimidinium cation, pyrazolium cation , Pyrazolinium cation, tetraalkylammonium cation, trialkylsulfonium cation, tetraalkylphosphonium cation and the like.
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 from 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.

  As the ionic compound (B), a quaternary ammonium salt is preferable. Specific examples of the quaternary ammonium salt include, for example, tributylmethylammonium N, N-bis (trifluoromethanesulfonyl) imide, tetrabutylammoniumbis (tributylammonium) Fluoromethylsulfonyl) imide, tetrabutylammonium bromide, tetrapentylammonium bromide, tetraoctylammonium bromide, ethyldimethylpropylammonium bis (trifluoromethylsulfonyl) imide, n-butyltrimethylammonium bis (trifluoromethanesulfonyl) imide, methyltrioctyl Ammonium bis (trifluoromethylsulfonyl) imide, tributylmethylammonium methylsulfate, tributylmethylammonium Tyl sulfate, tetrabutylammonium bis (trifluoromethylsulfonyl) imide, tetraethylammonium trifluoromethanesulfonate, tetrabutylammonium benzoate, tetrabutylammonium methanesulfate, tetrabutylammonium nonafluorobutanesulfonate, tetra-n-butylammonium hexafluorophosphate , Tetrabutylammonium trifluoroacetate, tetrahexylammonium tetrafluoroborate, tetrahexylammonium bromide and the like.

  From the viewpoint of the balance between the antistatic performance and the durability, an ionic compound in which the anionic component of the ionic compound (B) is a fluorine-containing anion is preferable. In particular, lithium trifluoromethanesulfonate (manufactured by Tokyo Chemical Industry Co., Ltd.) ), Lithium N, N-bis (trifluoromethanesulfonyl) imide (manufactured by Sanko Chemical) and tributylmethylammonium N, N-bis (trifluoromethanesulfonyl) imide (manufactured by 3M) are preferably used.

  In the case of an ammonium-based ionic compound as the cation component of the ionic compound (B), it is preferably an alkylammonium cation, and the number of carbon atoms in the alkyl chain is high in terms of excellent compatibility with the acrylic resin (A). An alkylammonium cation having an alkyl group of 1 to 6 is particularly preferred. On the other hand, in the case of an alkali metal salt, a lithium cation, a sodium cation, a potassium cation or the like is preferable, and a lithium cation is particularly preferable in that it is particularly excellent in wet heat resistance.

When the ionic compound (B) has a melting point of less than 25 ° C., it tends to hardly precipitate as a solid. When the ionic compound (B) has a melting point of 25 ° C. or more, the pressure-sensitive adhesive is less likely to be plasticized and has excellent durability. .
The melting point of the ionic compound (B) is preferably -100 ° C or higher, particularly 0 ° C or higher, and more preferably 25 ° C or higher. Tend to be.

The content of the ionic compound (B) is preferably 1 to 30 parts by weight, particularly preferably 2 to 25 parts by weight, more preferably 2.5 parts by weight, based on 100 parts by weight of the acrylic resin (A). -20 parts by weight, particularly preferably 4-15 parts by weight.
If the content of the ionic compound (B) is too small, the antistatic performance is lowered, and malfunction of the touch panel or display unevenness of the liquid crystal cell tends to occur due to static electricity. If the content is too large, the pressure-sensitive adhesive layer is plasticized. Or bleed, and the durability tends to decrease.

  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).

<Crosslinking agent (C)>
The cross-linking agent (C) reacts with a functional group in the acrylic resin (A) to form a cross-linked structure, and is, for example, an isocyanate-based cross-linking agent, an epoxy-based cross-linking agent, an aziridine-based cross-linking agent, or 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 adhesiveness 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, tolylene diisocyanate-based crosslinking agent such as 2,6-tolylene diisocyanate, xylylene diisocyanate-based crosslinking agent such as 1,3-xylylene diisocyanate, Aromatic isocyanate-based crosslinking agents such as diphenylmethane-based crosslinking agents such as diphenylmethane-4,4-diisocyanate, and naphthalene diisocyanate-based 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, and isocyanurates of the above isocyanate compounds. .

  Among these isocyanate-based cross-linking agents, tolylene diisocyanate-based cross-linking agents are preferable in terms of pot life and durability, and xylylene diisocyanate-based cross-linking agents or isocyanurate skeleton-containing isocyanate cross-linking agents are preferable in terms of shortening aging time. An aromatic-free isocyanate-based crosslinking agent is 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 tetramethylolmethane-tri-β-aziridinylpropionate, trimethylolpropane-tri-β-aziridinylpropionate, and 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, hexabutoxymethylmelamine, hexapentyloxymethylmelamine, hexahexyloxymethylmelamine, and melamine resin.

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

  Examples of the amine crosslinking agent include hexamethylenediamine, triethyldiamine, polyethyleneimine, hexamethylenetetraamine, diethylenetriamine, triethyltetraamine, isophoronediamine, amino resin, polyamide, and the like.

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

  The content of the crosslinking agent (C) is preferably 0.005 to 30 parts by weight, particularly preferably 0.01 to 10 parts by weight, more preferably 0.01 to 10 parts by weight, based on 100 parts by weight of the acrylic resin (A). Is from 0.03 to 5 parts by weight, particularly preferably from 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 tends to decrease and the substrate tends to be warped, or long-time aging tends to be 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, and is contained in the pressure-sensitive adhesive composition of the present invention. Is preferred.

  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 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, RI-8020 type, sensitivity 32)
-Column: TSKgel guardcolumn HHR-H (1) (Tosoh Corp., φ6 mm × 4 cm), TSKgel GMHHR-N (2) (Tosoh Corp., φ7.8 mm × 30 cm)
-Solvent: tetrahydrofuran (THF)
-Column temperature: 23 ° C
・ Flow rate: 1.0 mL / min

The silane coupling agent (D) is an oligomer type 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 an alkyl group-containing silane compound such as methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane Is a mercapto group-containing oligomer type Run coupling agent: γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, methyltri (glycidyl) An epoxy group obtained by partially hydrolyzing and polycondensing a part of epoxy group-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 3 to 50% by weight, and more preferably 5 to 25% by weight to balance durability and reworkability. It is preferable because it is excellent.

  Specific examples of the monomer-type or oligomer-type silane coupling agent (D) include a commercially available epoxy group-containing silane coupling agent “KBM-403” and “X-41” manufactured by Shin-Etsu Chemical Co., Ltd. 1053 "," X-41-1059A "," X-24-9590 "," KBM-803 "," X-41-1805 "," X-41-1810 "," X-41-1818 "and the like. No.

The content of the silane coupling agent (D) is preferably 0.001 to 2 parts by weight, particularly preferably 0.005 to 1 part by weight, based on 100 parts by weight of the acrylic resin (A). , 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 low, the reworkability tends to decrease, and if it is too high, the silane coupling agent bleeds and the durability tends to decrease.

<Other 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 components, a resin component, an acrylic monomer, a polymerization inhibitor, an antioxidant, a corrosion inhibitor, a crosslinking accelerator, a radical Various additives such as a generator, a peroxide, a radical scavenger, an ultraviolet absorber, an antioxidant, a plasticizer, a pigment, a stabilizer, and 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 and the like contained in the raw materials for producing the components of the pressure-sensitive adhesive composition.

  The content of the other components is preferably 5 parts by weight or less, particularly preferably 1 part by weight or less, more preferably 0.5 part by weight or less based on 100 parts by weight of the acrylic resin (A). is there. 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 components, the pressure-sensitive adhesive composition of the present invention is mixed. You can get things.

  The mixing method is not particularly limited, and various methods such as a method of mixing each component at once, and 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 and forming a pressure-sensitive adhesive layer composed of 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.

The method for producing the optical member with the pressure-sensitive adhesive layer is as follows: [1] After applying and drying the pressure-sensitive adhesive composition on the optical member, laminating a release sheet, and heating at room temperature (23 ° C.) or in a heated state. A method of performing treatment by aging on at least one side, [2] applying a pressure-sensitive adhesive composition on a release sheet, drying and then bonding an optical member, and performing aging on at least one of a normal temperature and a heated state. And a method of performing the treatment. 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 description, the optical member is particularly effective when it is a polarizing plate, but the above method can be used also 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.

  When applying the above-mentioned 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 10 to 60% by weight. 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 these, ethyl acetate and methyl ethyl ketone are preferably used from the viewpoints 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 30 to 98% by weight, particularly preferably 35 to 95% by weight, more preferably 50 to 50% by weight, from the viewpoint of durability performance and suppression of a decrease in the degree of polarization. ~ 90% by weight. If the gel fraction is too low, foaming tends to occur in a high-temperature environment, and if it is too high, floating and peeling tend 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 from an adhesive film formed by forming an adhesive layer on a base material such as an optical member, particularly 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 with a finger, and has good wettability when actually affixed to an adherend. .

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, particularly preferably less than 1.0 × 10 ¹⁰ Ω / cm ² , more preferably less than 1.0 × 10 ¹⁰ Ω / cm ^2. Is less than 8.0 × 10 ⁹ Ω / cm ² , particularly preferably less than 5.0 × 10 ⁹ Ω / cm ² . If the surface resistivity is too high, the pressure-sensitive adhesive tends to be easily charged, and tends to cause display unevenness due to static electricity when used for a liquid crystal display.

  In the present invention, the optical member with an adhesive layer, especially the 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 capable of achieving both high antistatic performance and durability even under a high-temperature environment or a high-temperature and high-humidity environment, and a pressure-sensitive adhesive for an optical member, particularly polarized light. It is useful as a pressure-sensitive adhesive for a polarizing plate for bonding a plate and a glass substrate.

  Examples of the protective film constituting the polarizing plate include a triacetyl cellulose film, an acrylic film, a polyethylene film, a polypropylene film, a cycloolefin film, and the like.The present invention relates to a polarizing plate using any of the protective films. Although it is also preferably used, a polarizing plate laminated with a cycloolefin-based film is particularly preferred in that the effects of the present invention can be 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 durability. Become better.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited to a following example, unless the summary is exceeded. In the examples, “parts” and “%” mean on a weight basis.

First, various acrylic resins (A) were prepared as described below. The weight average molecular weight, the degree of dispersion, and the glass transition temperature of the acrylic resin (A) were measured according to the methods described above.
In addition, about the measurement of the viscosity, it measured according to the 4.5.3 rotational viscometer method of JISK5400 (1990).

<Acrylic resin (A)>
The following were prepared as raw material monomers for the acrylic resin (A) (see Table 1).

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

(Macromonomer 1):
Acrylic macromonomer having 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 polymethyl methacrylate 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.)
(Macromonomer 3):
Acrylic macromonomer containing polymethyl methacrylate as a main component (manufactured by Mitsubishi Chemical Corporation, PMMA = 100%, number average molecular weight 45,000, dispersity 2.0, calculated glass transition temperature 105 ° C.)
In addition, about the macromonomer 3, it measured by the following method.
That is, a column: Shodex GPC KF-806L (exclusion limit molecular weight: 2 × 10 ⁷ , separation range) in a high performance liquid chromatograph (“Waters 2695 (body)” and “Waters 2414 (detector)” manufactured by Waters Japan). : 100 to 2 × 10 ⁷ , theoretical plate number: 10,000 plates / unit, filler material: styrene-divinylbenzene copolymer, filler particle size: 10 μm). did. The weight average molecular weight was measured in the same manner, and the degree of dispersion determined from the weight average molecular weight and the number average molecular weight was determined.

[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 and diluted with an acrylic resin (A-1) solution (solid content 26. 2%, viscosity 4,500 mPa · s / 25 ° C., acrylic resin (A-1): weight-average molecular weight 1,110,000, calculated glass transition temperature −51.6 ° C., and dispersity 4) were obtained.

[Production of acrylic resin (A'-1)]
In a four-necked round-bottom flask equipped with a reflux condenser, a stirrer, a nitrogen gas inlet, and a thermometer, 1 part of the prepared macromonomer 2, 90.3 parts of n-butyl acrylate (a2), 8 parts of 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. Was raised to the boiling point to start the reaction. Next, 30 parts of an ethyl acetate solution containing 0.04% of AIBN was added dropwise, and the mixture was reacted at reflux temperature for 3.25 hours, then diluted with ethyl acetate and diluted with an acrylic resin (A′-1) solution (solid content 26). 0.5%, viscosity 2,385 mPa · s / 25 ° C., acrylic resin (A′-1): weight average molecular weight 1,030,000, calculated glass transition temperature −51.6 ° C., and dispersity 4).

[Production of acrylic resin (A'-2)]
In a four-necked round bottom flask equipped with a reflux condenser, a stirrer, a nitrogen gas inlet, and a thermometer, 1 part of the prepared macromonomer 3, 90.3 parts of n-butyl acrylate (a2), 8 parts of 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. Was raised to the boiling point to start the reaction. 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 26). 2.0%, a viscosity of 12,050 mPa · s / 25 ° C., an acrylic resin (A′-2): a weight average molecular weight of 1.3 million, a calculated glass transition temperature of −51.6 ° C., and a dispersity of 5) were obtained.

[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, 5 parts of the prepared macromonomer 2, 86.3 parts of n-butyl acrylate (a2), 8 parts of 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. Was raised to the boiling point to start the reaction. 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 35%). 0.8%, viscosity 770 mPa · s / 25 ° C., acrylic resin (A′-3): weight average molecular weight 480,000, calculated glass transition temperature −47.7 ° C., and dispersion degree 3).

[Production of acrylic resin (A'-4)]
91.3 parts of n-butyl acrylate (a2), 8 parts of 2-hydroxyethyl acrylate (a3), and acryl were placed in a four-neck round bottom flask equipped with a reflux condenser, a stirrer, a nitrogen gas inlet, and a thermometer. 0.7 parts of acid (a3), 53 parts of ethyl acetate, 42 parts of acetone, and 0.013 part of azobisisobutyronitrile (AIBN) as a polymerization initiator were charged, and the reaction was started by raising the internal temperature to the boiling point. Was. Then, the mixture was reacted at reflux temperature for 3.25 hours while 30 parts of an ethyl acetate solution containing 0.04% of AIBN was added dropwise, diluted with ethyl acetate, and then diluted with ethyl acetate to obtain an acrylic resin (A′-4) solution (solid content 21%). 0.5%, viscosity 5,000 mPa · s / 25 ° C., acrylic resin (A′-4): 1.35 million weight average molecular weight, calculated glass transition temperature −52.5 ° C., dispersity 5).

The monomers used above were from the following manufacturers.
-Butyl acrylate (BA) (manufactured by Mitsubishi Chemical Corporation, Tg-56 ° C)
-2-hydroxyethyl acrylate (HEA) (Tg-15 ° C, manufactured by Osaka Organic Chemical Company)
Acrylic acid (AAc) (manufactured by Mitsubishi Chemical Corporation, Tg106 ° C)
The above Tg is the Tg of a 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.)
(B-2): Lithium N, N-bis (trifluoromethanesulfonyl) imide 56% by weight solution [solvent: tetraethylene glycol dimethyl ether (manufactured by Sanko Chemical Co., Sanconol TGR)]
(B-3): Tributylmethylammonium N, N-bis (trifluoromethanesulfonyl) imide (3M, FC-4400)

<Crosslinking agent (C)>
The following were prepared as a crosslinking agent (C).
(C-1): an 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).
The weight average molecular weight of the silane coupling agent (D) was measured according to the method described above. For the alkoxy group content, reactive functional group, epoxy equivalent or mercapto equivalent, and contained alkoxy group, catalog values were adopted unless otherwise specified.

(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, functional group equivalent: 592 g / mol, contained alkoxy group: 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 to 3, Comparative Examples 1 to 5>
The above components were blended as shown in Table 2 below, and the solid content concentration was adjusted to 20% in Comparative Example 1, 35% in Comparative Example 2, and 15% in the others with ethyl acetate to obtain an adhesive composition. Was.

  Using the pressure-sensitive adhesive composition obtained above, evaluation samples were prepared as described below, and the following performances were evaluated. The evaluation results are shown in Table 2 above.

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

<Durability 1: Glass>
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 (Eagle XG, manufactured by Corning Incorporated, thickness: 1.1 mm), 2 kg. After two reciprocations with a roller, bonding was performed, and an autoclave treatment (0.5 MPa × 50 ° C. × 20 minutes) was performed to prepare a sample for a durability test.

(1) Heat resistance test The following evaluation was performed on the polarizing plate after the obtained sample was exposed under the condition of heat resistance (95 ° C x 100 hours).
(2) Moisture / Heat Resistance Test The following evaluation was performed on the polarizing plate after exposing the obtained sample under the condition of moisture / heat resistance (85 ° C. × 85% RH × 100 hours).
(Evaluation criteria)
・ ・ ・: Foaming is not observed on the entire surface of the polarizing plate or floating is not observed on the end portion.

<Durability 2: SUS-BA plate>
The obtained polarizing plate with an adhesive layer [I] is cut into a size of 165 mm x 95 mm, the release sheet is peeled off, the adhesive layer surface is pressed against a mirror-finished stainless steel plate (SUS-BA plate) and reciprocated two times with a 2 kg roller. After bonding, autoclave treatment (0.5 MPa × 50 ° C. × 20 minutes) was performed to prepare a sample for a durability test.
With respect to the obtained sample, the following evaluation was performed on the polarizing plate after exposure under the condition of wet heat resistance (85 ° C. × 85% RH × 100 hours).
(Evaluation criteria)
・ ・ ・: Foaming is not observed on the entire surface of the polarizing plate or no floating is observed at the end. X: Foaming is observed on the entire surface of the polarizing plate or floating is observed at the end.

<Antistatic performance>
(Surface resistivity)
After the polarizing plate with the pressure-sensitive adhesive layer [I] is allowed to stand for 24 hours in an atmosphere of 23 ° C. × 50% RH, 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).
(Evaluation criteria)
・ ・ ・: Less than 5.0 × 10 ⁹ Ω / cm ² 〇: 5.0 × 10 ⁹ Ω / cm ² or more and less than 8.0 × 10 ⁹ Ω / cm ² △: 8.0 × 10 ⁹ Ω / cm ² or more and less than 1.0 × 10 ¹⁰ Ω / cm ² ×... 1.0 × 10 ¹⁰ Ω / cm ² or more

<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 (%).

According to the above results, the pressure-sensitive adhesive composition containing the acrylic resin (A) obtained by polymerizing the polymerization component containing the macromonomer (a1) having a polar group in the side chain and the ionic compound (B) is used. It can be seen that the samples Nos. 1 to 3 form an adhesive which can achieve both high durability and antistatic performance when glass and metal are used as adherends even in a high temperature environment or a high temperature and high humidity environment.
On the other hand, in Comparative Examples 1 to 3 using a macromonomer having no polar group in the side chain, it can be seen that all of the adhesives are inferior in durability.
Furthermore, in Comparative Example 4 in which the amount of the antistatic agent was small and the macromonomer was not used, the durability was excellent, but the antistatic performance was poor. In Comparative Example 5 in which the amount of the ionic compound (B) having an antistatic effect was increased to increase the antistatic performance of Comparative Example 4, the antistatic performance was excellent, but the durability was poor. .
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 or a high-temperature and high-humidity environment.

  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 at the time of manufacturing a liquid crystal display device, Even in a high-temperature environment or a high-temperature and high-humidity environment, it exhibits excellent durability and has excellent antistatic performance. It is useful as a pressure-sensitive adhesive for polarizing plates for bonding a liquid crystal cell glass substrate, a substrate provided with a conductive layer, and the like.

Claims (12)

  An adhesive composition containing an acrylic resin (A) and an ionic compound (B), wherein the acrylic resin (A) contains a polymerization component containing a macromonomer (a1) having a polar group in a side chain. An adhesive composition, which is an acrylic resin obtained by polymerization.   The pressure-sensitive adhesive composition according to claim 1, wherein the macromonomer (a1) having a polar group in a side chain is a macromonomer having a hydroxyl group in a side chain.   3. The adhesive according to claim 1, wherein the macromonomer (a1) having a polar group in a side chain is an acrylic macromonomer having a structure derived from an alkyl (meth) acrylate and a hydroxyl group-containing (meth) acrylate. Composition.   The content ratio of the macromonomer (a1) having a polar group in a side chain is 0.1 to 30% by weight based on a polymerization component constituting the acrylic resin (A). The pressure-sensitive adhesive composition according to any one of the above. The pressure-sensitive adhesive according to any one of claims 1 to 4, wherein the acrylic resin (A) is an acrylic resin obtained by further polymerizing a polymerization component containing a polar group-containing monomer (a3). Composition.   The polar group-containing monomer (a3) is a hydroxyl group-containing monomer, and the content ratio of the hydroxyl group-containing monomer is 0.01 to 30% by weight based on a polymerization component constituting the acrylic resin (A). The pressure-sensitive adhesive composition according to claim 5.   The pressure-sensitive adhesive according to any one of claims 1 to 6, wherein the content of the ionic compound (B) is 1 to 30 parts by weight based on 100 parts by weight of the acrylic resin (A). Composition.   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).   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 a liquid crystal cell bonded together with the adhesive according to claim 10.