WO2018155238A1 - Adhesive composition, adhesive layer, and optical film having adhesive layer - Google Patents

Abstract

The present invention provides an adhesive composition in which it is possible to prevent white irregularities even in low-temperature environments and which can be used for image display panels having exceptional anti-static properties, an adhesive layer, and an optical film having an adhesive layer. This adhesive composition is characterized by containing a (meth)acrylic polymer and an ionic compound having a melting point of -5°C or lower.

Description

Adhesive composition, adhesive layer, and optical film with adhesive layer

The present invention relates to a pressure-sensitive adhesive composition, a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition, and an optical film with a pressure-sensitive adhesive layer using the pressure-sensitive adhesive layer.

In general, a liquid crystal display device has a polarizing film bonded to both sides of a liquid crystal cell via an adhesive layer due to its image forming method. In addition, a liquid crystal display device in which a touch panel is mounted on a display screen has been put into practical use.

At the time of manufacturing the liquid crystal display device, when the polarizing film with the pressure-sensitive adhesive layer is attached to the liquid crystal cell, the release film is peeled off from the pressure-sensitive adhesive layer of the polarizing film with the pressure-sensitive adhesive layer. Static electricity is generated. The static electricity generated in this way affects the orientation of the liquid crystal inside the liquid crystal display device, leading to defects. For example, if white unevenness occurs during black display due to static electricity during use of a liquid crystal display device, the phenomenon that the white unevenness does not disappear for several minutes occurs and the display characteristics of the screen deteriorate. Had a point.

In addition, when the liquid crystal display device is manufactured, after the polarizing film with the pressure-sensitive adhesive layer is attached to the liquid crystal cell, static electricity is generated when the protective film on the surface of the polarizing film is peeled off and the appearance inspection is performed through the backlight. Occurs, liquid crystal orientation is disturbed, and white unevenness occurs during black display. When the phenomenon that the white unevenness does not disappear for a few minutes occurs, the inspection is stagnated and the productivity is greatly reduced. Further, even after mounting on a television or the like, similar white unevenness may occur due to static electricity generated when the backlight and the polarizing film are rubbed.

The generation of static electricity can be suppressed, for example, by forming an antistatic layer on the outer surface of the polarizing film, but the effect is small and there is a problem that the generation of static electricity cannot be fundamentally prevented. Therefore, in order to suppress the occurrence of static electricity at a fundamental position, it is required to provide an antistatic function to the adhesive layer. As means for imparting an antistatic function to the pressure-sensitive adhesive layer, for example, it has been proposed to blend an ionic compound as the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer (see, for example, Patent Document 1).

In patent document 1, it is excellent in antistatic property by using an ionic liquid which is liquid at room temperature and an alkali metal salt which is solid at room temperature as an ionic compound which is an antistatic agent for the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer. Is described.

JP 2006-152235 A

However, even when a liquid or solid ionic compound is used at room temperature, in a low-temperature environment (for example, 0 ° C. or less), it does not disappear when white unevenness occurs or is long before it disappears. Providing antistatic properties in a low temperature environment, such as requiring time, has become a problem. Further, under the low temperature environment, it is difficult to obtain sufficient antistatic properties even if the blending amount of the ionic compound is increased.

Accordingly, the present invention provides a pressure-sensitive adhesive composition, a pressure-sensitive adhesive layer, and an optical film with a pressure-sensitive adhesive layer that can prevent white unevenness even in a low-temperature environment and can be used for image display panel applications having excellent antistatic properties. With the goal.

As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by the following pressure-sensitive adhesive composition, and have completed the present invention.

That is, the pressure-sensitive adhesive composition of the present invention is characterized by containing a (meth) acrylic polymer and an ionic compound having a melting point of −5 ° C. or lower.

In the pressure-sensitive adhesive composition of the present invention, the conductivity of the ionic compound at 25 ° C. is preferably 10 mS / cm or more.

In the pressure-sensitive adhesive composition of the present invention, the ionic compound is an ionic liquid, the ionic liquid is an organic cation-anion salt, and the anion is bis (fluorosulfonyl) imide anion and / or bis Preferably it is a (trifluoromethanesulfonyl) imide anion.

The pressure-sensitive adhesive layer of the present invention is preferably formed of the pressure-sensitive adhesive composition.

In the optical film with an adhesive layer of the present invention, the adhesive layer is preferably formed on at least one side of the optical film.

The pressure-sensitive adhesive composition of the present invention contains an ionic compound having a specific melting point together with a (meth) acrylic polymer as a base polymer, so that the ionic compound remains liquid even in a low temperature environment. It is difficult to limit the movement of ions necessary for electrostatic charge neutralization, can suppress white unevenness due to peeling charging, and has an antistatic property with an antistatic property, and with the adhesive layer An optical film can be obtained and is useful.

<Adhesive composition>
<Meth) acrylic polymer>
The pressure-sensitive adhesive composition of the present invention is characterized by containing a (meth) acrylic polymer. The (meth) acrylic polymer is a base polymer and can be used without particular limitation as long as it has adhesiveness, but usually contains an alkyl (meth) acrylate as a main component as a monomer unit. (Meth) acrylate refers to acrylate and / or methacrylate, and (meth) of the present invention has the same meaning.

Examples of the alkyl (meth) acrylate that constitutes the main skeleton of the (meth) acrylic polymer include linear or branched alkyl groups having 1 to 18 carbon atoms. For example, the alkyl group includes methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, amyl group, hexyl group, cyclohexyl group, heptyl group, 2-ethylhexyl group, isooctyl group, nonyl group, decyl group. Group, isodecyl group, dodecyl group, isomyristyl group, lauryl group, tridecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, and the like. These can be used alone or in combination. These alkyl groups preferably have an average carbon number of 3 to 9.

In the pressure-sensitive adhesive composition of the present invention, a monomer containing a polar functional group such as a hydroxyl group, a carboxyl group, an amino group, and an amide group can be used as a monomer unit. By using a (meth) acrylic polymer containing a monomer containing the polar functional group as a monomer unit, the ionic compound can be easily held in the pressure-sensitive adhesive layer, and the ionic compound on the surface of the pressure-sensitive adhesive layer This is a preferable embodiment.

A hydroxyl group-containing monomer can be used for the (meth) acrylic polymer. The hydroxyl group-containing monomer is a compound containing a hydroxyl group in its structure and a polymerizable unsaturated double bond such as a (meth) acryloyl group or a vinyl group, more preferably a hydroxyl group-containing (meth) acrylic. System monomers. Specific examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8- Examples thereof include hydroxyalkyl (meth) acrylate and (4-hydroxymethylcyclohexyl) -methyl acrylate, such as hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, and 12-hydroxylauryl (meth) acrylate. Among the hydroxyl group-containing monomers, 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate are preferable from the viewpoint of durability, and 4-hydroxybutyl (meth) acrylate is particularly preferable.

The carboxyl group-containing monomer is a compound containing a carboxyl group in its structure and a polymerizable unsaturated double bond such as a (meth) acryloyl group or a vinyl group. Specific examples of the carboxyl group-containing monomer include (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid and the like. Among the carboxyl group-containing monomers, acrylic acid is preferable from the viewpoints of copolymerizability, cost, and adhesive properties (adhesive strength and the like).

In the (meth) acrylic polymer, an amino group-containing monomer can be used as a monomer unit. The amino group-containing monomer is a compound containing an amino group in its structure and a polymerizable unsaturated double bond such as a (meth) acryloyl group or a vinyl group. Specific examples of the amino group-containing monomer include aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate and the like.

In the (meth) acrylic polymer, an amide group-containing monomer can be used as a monomer unit. The amide group-containing monomer is a compound containing an amide group in its structure and a polymerizable unsaturated double bond such as a (meth) acryloyl group or a vinyl group. Specific examples of the amide group-containing monomer include (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N-isopropylacrylamide, N-methyl (meth) acrylamide, N- Butyl (meth) acrylamide, N-hexyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methylol-N-propane (meth) acrylamide, aminomethyl (meth) acrylamide, aminoethyl (meth) acrylamide, mercaapt Acrylamide monomers such as methyl (meth) acrylamide and mercaptoethyl (meth) acrylamide; N-acrylates such as N- (meth) acryloylmorpholine, N- (meth) acryloylpiperidine and N- (meth) acryloylpyrrolidine Acryloyl heterocyclic monomers; N- vinyl - pyrrolidone, N- vinyl-containing lactam monomers such as N- vinyl -ε- caprolactam. The amide group-containing monomer is preferable for satisfying durability, and among the amide group-containing monomers, an N-vinyl group-containing lactam monomer is particularly preferable.

An aromatic ring-containing (meth) acrylate can be further used for the (meth) acrylic polymer. An aromatic ring-containing (meth) acrylate is a compound containing an aromatic ring structure in its structure and a (meth) acryloyl group. Examples of the aromatic ring include a benzene ring, a naphthalene ring, and a biphenyl ring. The aromatic ring-containing (meth) acrylate satisfies the durability and can improve display unevenness due to white spots in the peripheral portion. Specific examples of the aromatic ring-containing (meth) acrylate include, for example, benzyl (meth) acrylate, phenyl (meth) acrylate, o-phenylphenol (meth) acrylate phenoxy (meth) acrylate, phenoxyethyl (meth) acrylate, phenoxypropyl (Meth) acrylate, phenoxydiethylene glycol (meth) acrylate, ethylene oxide modified nonylphenol (meth) acrylate, ethylene oxide modified cresol (meth) acrylate, phenol ethylene oxide modified (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) Acrylate, methoxybenzyl (meth) acrylate, chlorobenzyl (meth) acrylate, cresyl (meth) acrylate, polystyryl ( A) Having a benzene ring such as acrylate; hydroxyethylated β-naphthol acrylate, 2-naphthoethyl (meth) acrylate, 2-naphthoxyethyl acrylate, 2- (4-methoxy-1-naphthoxy) ethyl (meth) acrylate And those having a naphthalene ring such as biphenyl (meth) acrylate. In particular, the aromatic ring-containing (meth) acrylate is preferably benzyl (meth) acrylate or phenoxyethyl (meth) acrylate, particularly preferably phenoxyethyl (meth) acrylate, from the viewpoint of adhesive properties or durability.

These copolymerized monomers serve as reaction points with the crosslinking agent when the pressure-sensitive adhesive composition contains a crosslinking agent. In particular, the carboxyl group-containing monomer and the hydroxyl group-containing monomer are preferably used for improving the cohesiveness and heat resistance of the resulting pressure-sensitive adhesive layer because they are highly reactive with the intermolecular crosslinking agent.

The (meth) acrylic polymer contains a predetermined amount of each monomer as a monomer unit in a weight ratio of all monomers (100% by weight). The weight ratio of the alkyl (meth) acrylate can be set as the remainder of the monomer other than the alkyl (meth) acrylate, specifically, preferably 65% by weight or more, more preferably 70% by weight or more, and 75 to 99. 9% by weight is more preferable, and 80 to 99% by weight is particularly preferable. Setting the weight ratio of the alkyl (meth) acrylate within the above range is preferable for securing adhesiveness.

The (meth) acrylic polymer preferably contains a monomer other than the alkyl (meth) acrylate as a monomer unit in an amount of 0.1% by weight or more, more preferably 0.2 to 35% by weight. It is more preferably 5 to 30% by weight, and particularly preferably 1 to 25% by weight. When the weight ratio of the monomer other than the alkyl (meth) acrylate is less than 0.1% by weight, an ionic compound is deposited on the surface of the pressure-sensitive adhesive layer when a large amount of an ionic liquid that is an ionic compound is blended, This is not preferable because it may cause problems in appearance such as white turbidity in a low temperature environment and foaming or peeling in a low temperature environment.

In the (meth) acrylic polymer, it is not particularly necessary to contain other monomer units in addition to the monomer units, but (meth) acryloyl groups are intended to improve adhesiveness and heat resistance. Alternatively, one or more copolymerization monomers having a polymerizable functional group having an unsaturated double bond such as a vinyl group can be introduced by copolymerization.

Specific examples of such copolymerization monomers include: anhydride-containing monomers such as maleic anhydride and itaconic anhydride; caprolactone adducts of acrylic acid; allyl sulfonic acid, 2- (meth) acrylamide-2-methyl Examples thereof include sulfonic acid group-containing monomers such as propanesulfonic acid, (meth) acrylamide propanesulfonic acid and sulfopropyl (meth) acrylate; and phosphoric acid group-containing monomers such as 2-hydroxyethylacryloyl phosphate.

Further, alkylaminoalkyl (meth) acrylates such as aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, and t-butylaminoethyl (meth) acrylate; methoxyethyl (meth) acrylate, ethoxyethyl ( Alkoxyalkyl (meth) acrylates such as meth) acrylate; N- (meth) acryloyloxymethylene succinimide, N- (meth) acryloyl-6-oxyhexamethylene succinimide, N- (meth) acryloyl-8-oxyoctamethylene succinimide, etc. Succinimide monomers: N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide and other maleimide monomers; N-methylitaconimide, Examples of monomers for modification purposes include itaconic imide monomers such as ethylethylaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylruitaconimide, and N-laurylitaconimide. As mentioned.

Furthermore, as modification monomers, vinyl monomers such as vinyl acetate and vinyl propionate; cyanoacrylate monomers such as acrylonitrile and methacrylonitrile; epoxy group-containing (meth) acrylates such as glycidyl (meth) acrylate; polyethylene glycol (meth) Glycol-based (meth) acrylates such as acrylate, polypropylene glycol (meth) acrylate, methoxyethylene glycol (meth) acrylate, methoxypolypropylene glycol (meth) acrylate; tetrahydrofurfuryl (meth) acrylate, fluorine (meth) acrylate, silicone (meta (Meth) acrylate monomers such as acrylate and 2-methoxyethyl acrylate can also be used. Furthermore, isoprene, butadiene, isobutylene, vinyl ether and the like can be mentioned.

Furthermore, examples of copolymerizable monomers other than the above include silane-based monomers containing silicon atoms. Examples of the silane monomer include 3-acryloxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 4-vinylbutyltrimethoxysilane, 4-vinylbutyltriethoxysilane, and 8-vinyloctyltrimethoxysilane. , 8-vinyloctyltriethoxysilane, 10-methacryloyloxydecyltrimethoxysilane, 10-acryloyloxydecyltrimethoxysilane, 10-methacryloyloxydecyltriethoxysilane, 10-acryloyloxydecyltriethoxysilane, and the like.

Examples of copolymer monomers include tripropylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, bisphenol A diglycidyl ether di (meth) acrylate, neo Pentyl glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate (Meth) acryloyl such as esterified product of (meth) acrylic acid and polyhydric alcohol such as caprolactone-modified dipentaerythritol hexa (meth) acrylate Groups such as polyfunctional monomers having 2 or more unsaturated double bonds such as vinyl groups, vinyl groups and the like, and functional groups similar to the monomer components on the backbone of polyester, epoxy, urethane, etc. (meth) acryloyl groups, vinyl groups, etc. Polyester (meth) acrylate, epoxy (meth) acrylate, urethane (meth) acrylate, or the like to which two or more saturated double bonds have been added can also be used.

The polymerization ratio of the copolymerization monomer in the (meth) acrylic polymer is about 0 to 10% by weight, further about 0 to 7% by weight in the total monomer (100% by weight) of the (meth) acrylic polymer, Further, it is preferably about 0 to 5% by weight.

The (meth) acrylic polymer usually has a weight average molecular weight (Mw) of 500,000 to 3,000,000. In view of durability, particularly heat resistance, the weight average molecular weight (Mw) is more preferably 1 million to 2.5 million, and even more preferably 1.1 million to 2 million. If the weight average molecular weight (Mw) is smaller than 500,000, it is not preferable in terms of heat resistance. Moreover, when a weight average molecular weight (Mw) becomes larger than 3 million, there exists a tendency for an adhesive layer to become hard easily and peeling tends to generate | occur | produce. In addition, a weight average molecular weight (Mw) is measured from GPC (gel permeation chromatography), and is calculated | required from the value calculated by polystyrene conversion.

The (meth) acrylic polymer used in the present invention preferably has a glass transition temperature (Tg) of 0 ° C. or lower (usually −100 ° C. or higher), more preferably −5 ° C. or lower. More preferably, it is −10 ° C. or lower. When the glass transition temperature is higher than 0 ° C., the cohesive force is increased, the fluidity is lowered, and a sufficient adhesion area cannot be obtained and the adherend may not be fixed. In particular, Tg of −5 ° C. or lower is preferable because the (meth) acrylic polymer becomes soft, the ionic compound easily moves, and the antistatic performance is improved. The glass transition temperature of the (meth) acrylic polymer can be adjusted within the above range by appropriately changing the monomer component and composition ratio used. As the glass transition temperature of the (meth) acrylic polymer in the present invention, a measuring method using a dynamic viscoelastic device, a calculated value by the FOX equation, or the like can be used.

The production of such a (meth) acrylic polymer can be appropriately selected from known production methods such as solution polymerization, bulk polymerization, emulsion polymerization, and various radical polymerizations. Further, the (meth) acrylic polymer obtained may be a random copolymer, a block copolymer, a graft copolymer or the like. In addition, in a production method in which a polar substance is easily adsorbed on the molecular interface of a polymer, such as emulsion polymerization, the effect of eliminating white unevenness may be reduced because the ionic compound is strongly restrained in the polymer.

In solution polymerization, for example, ethyl acetate, toluene or the like is used as a polymerization solvent. As a specific example of solution polymerization, the reaction is carried out in an inert gas stream such as nitrogen and a polymerization initiator is added, and the reaction is usually performed at about 50 to 70 ° C. under reaction conditions for about 5 to 30 hours.

The polymerization initiator, chain transfer agent, emulsifier and the like used for radical polymerization are not particularly limited and can be appropriately selected and used. In addition, the weight average molecular weight of a (meth) acrylic-type polymer can be controlled by the usage-amount of a polymerization initiator and a chain transfer agent, and reaction conditions, The usage-amount is suitably adjusted according to these kinds.

<Ionic compounds>
The pressure-sensitive adhesive composition of the present invention contains an ionic compound having a melting point of −5 ° C. or lower. The pressure-sensitive adhesive composition of the present invention contains an ionic compound having a specific melting point, so that the ionic compound can maintain a liquid state even in a low temperature environment, and is necessary for neutralizing electrostatic charges. Since the movement of ions is difficult to be restricted, it is possible to obtain a pressure-sensitive adhesive layer excellent in antistatic properties and an optical film with the pressure-sensitive adhesive layer, which is useful because it can suppress white unevenness due to peeling charging. In addition, the melting point of the ionic compound is preferably −8 ° C. or lower, more preferably −10 ° C. or lower.

The electrical conductivity at 25 ° C. of the ionic compound is preferably 10 mS / cm or more, more preferably 12 mS / cm or more, and further preferably 15 mS / cm or more. It can be presumed that when the conductivity (25 ° C.) of the ionic compound is in the above range, it exhibits a high conductivity even at a low temperature, the mobility of the ionic compound is high, the antistatic performance is improved, and a preferred embodiment It becomes.

The ionic compound is an ionic liquid, the ionic liquid is an organic cation-anion salt, and the anion is a bis (fluorosulfonyl) imide anion and / or a bis (trifluoromethanesulfonyl) imide anion. It is preferable. When the ionic compound is an ionic liquid, a pressure-sensitive adhesive layer having a high antistatic effect can be obtained without impairing the pressure-sensitive adhesive properties. Although details of the reason why excellent antistatic properties can be obtained by using an ionic liquid are not clear, in particular, an ionic liquid contained in an ionic compound having a melting point of −5 ° C. or lower used in the present invention is an ordinary alkali metal salt. Compared to ionic solids and ionic solids, it has a low melting point (melting point -5 ° C. or lower), and therefore it is considered that molecular motion is easy and excellent antistatic ability can be obtained. In particular, an ionic liquid (melting point -5 ° C. or lower) whose melting point is lower than room temperature (25 ° C.) is excellent in that it does not easily precipitate in the adhesive (composition) even in a low temperature environment or during long-term storage. Appearance and stable antistatic properties can be obtained. In addition, the ionic liquid can be easily added and dispersed or dissolved in the pressure-sensitive adhesive. Furthermore, since the ionic liquid has no vapor pressure (non-volatile), it does not disappear with time and has a characteristic that antistatic properties can be obtained continuously. Furthermore, since the ionic liquid is also excellent in compatibility with the polymer, appearance defects and the like can be suppressed. Further, in the case of an ionic solid, segregation (crystals are likely to precipitate) easily occurs on the surface of the pressure-sensitive adhesive layer, causing a poor appearance (white turbidity) and a decrease in durability. It becomes.

The ionic liquid refers to a molten salt (organic cation-anion salt) that has a melting point of −5 ° C. or lower and exhibits a liquid state. The “organic cation-anion salt” as used in the present invention refers to an organic salt whose cation part is composed of an organic substance, and the anion part may be an organic substance or an inorganic substance. May be. The “organic cation-anion salt” herein does not include what is called an ionic solid.

Specific examples of the ionic liquid (the parentheses indicate melting points) are appropriately selected from the combination of the cation component and the anion component. For example, 1-butyl-3-methylpyridinium bis (trifluoromethanesulfonyl) Imido (−70 ° C.), butylmethylpiperidinium bis (trifluoromethanesulfonyl) imide (−25 ° C.), butylmethylpyrrolidinium bis (trifluoromethanesulfonyl) imide (−18 ° C.), 1-ethyl-3-methyl Examples include imidazolium bis (trifluoromethanesulfonyl) imide (−16.2 ° C.) and 1-ethyl-3-methylimidazolium bis (fluorosulfonyl) imide (−12.9 ° C.), and in particular, 1-ethyl-3 -Use of methylimidazolium bis (fluorosulfonyl) imide It is preferred. Since bis (fluorosulfonyl) imide has a smaller anion molecule than other ionic liquids, it has a higher charge transfer rate, for example, has a higher effect of eliminating white unevenness than bis (trifluoromethanesulfonyl) imide, and is a preferred embodiment. .

In addition, the said ionic compound may be used independently and may be used in mixture of 2 or more types.

The amount of the ionic compound contained in the pressure-sensitive adhesive composition of the present invention is preferably 0.1 to 20 parts by weight, and 0.5 to 15 parts by weight with respect to 100 parts by weight of the (meth) acrylic polymer. More preferred is 1 to 10 parts by weight. If the ionic compound is less than 0.1 parts by weight, the effect of improving the antistatic performance may not be sufficient. On the other hand, if the amount of the ionic compound is more than 20 parts by weight, the appearance defect such as precipitation / segregation of the ionic compound and white turbidity in a low temperature environment and durability may not be sufficient.

In addition to the ionic compound, other ionic compounds can be used as long as the characteristics of the present invention are not impaired. Examples of the other ionic compounds include ionic surfactants. Examples thereof include materials capable of imparting antistatic properties such as systems, conductive polymers, and conductive fine particles.

<Crosslinking agent>
The pressure-sensitive adhesive composition can contain a crosslinking agent. As the crosslinking agent, an organic crosslinking agent or a polyfunctional metal chelate can be used. Examples of the organic crosslinking agent include an isocyanate crosslinking agent, a peroxide crosslinking agent, an epoxy crosslinking agent, and an imine crosslinking agent. A polyfunctional metal chelate is one in which a polyvalent metal is covalently or coordinately bonded to an organic compound. Examples of polyvalent metal atoms include Al, Cr, Zr, Co, Cu, Fe, Ni, V, Zn, In, Ca, Mg, Mn, Y, Ce, Sr, Ba, Mo, La, Sn, Ti, and the like. Can be mentioned. Examples of the atom in the organic compound that is covalently bonded or coordinated include an oxygen atom, and examples of the organic compound include an alkyl ester, an alcohol compound, a carboxylic acid compound, an ether compound, and a ketone compound. Among these, it is more preferable to use an isocyanate-based crosslinking agent and / or a peroxide-based crosslinking agent as the crosslinking agent, and it is particularly preferable to use an isocyanate-based crosslinking agent and a peroxide-based crosslinking agent in combination. By using an isocyanate-based cross-linking agent, cohesion, prevention of peeling in durability tests, etc. can be taken into account. By using a peroxide-based cross-linking agent, processability, reworkability, cross-linking It is excellent in stability, peelability and the like. In addition, by using an isocyanate-based crosslinking agent and a peroxide-based crosslinking agent together, and using an antioxidant here, the radical crosslinking inhibition by oxygen is effectively suppressed by the antioxidant, while the pressure-sensitive adhesive layer A three-dimensional crosslinked network can be formed efficiently.

As the isocyanate-based crosslinking agent, a compound having at least two isocyanate groups can be used. For example, known aliphatic polyisocyanate, alicyclic polyisocyanate, aromatic polyisocyanate and the like generally used for urethanization reaction are used.

Examples of the aliphatic polyisocyanate include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, 2,4,4- Examples include trimethylhexamethylene diisocyanate.

Examples of the alicyclic isocyanate include 1,3-cyclopentene diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, and hydrogenated tolylene diisocyanate. Examples include hydrogenated tetramethylxylylene diisocyanate.

Examples of the aromatic diisocyanate include phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 2,2′-diphenylmethane diisocyanate, 4,4′-diphenylmethane diisocyanate, 4, Examples include 4'-toluidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, xylylene diisocyanate, and the like.

Examples of the isocyanate-based crosslinking agent include the above-mentioned diisocyanate multimers (dimers, trimers, pentamers, etc.), urethane-modified products reacted with polyhydric alcohols such as trimethylolpropane, urea-modified products, and biuret-modified products. Body, alphanate modified body, isocyanurate modified body, carbodiimide modified body and the like.

The isocyanate-based crosslinking agent is preferably an aliphatic polyisocyanate and an aliphatic polyisocyanate-based compound that is a modified product thereof. Aliphatic polyisocyanate compounds are more flexible in cross-linking structures than other isocyanate cross-linking agents, tend to relieve stress associated with the expansion / contraction of optical films, and do not easily peel off in durability tests. . As the aliphatic polyisocyanate compound, hexamethylene diisocyanate and modified products thereof are particularly preferable.

Commercially available products of the isocyanate-based crosslinking agent include, for example, trade names “Millionate MT” “Millionate MTL” “Millionate MR-200” “Millionate MR-400” “Coronate L” “Coronate HL” “Coronate HX” [above, Manufactured by Tosoh Corporation; trade names “Takenate D-110N” “Takenate D-120N” “Takenate D-140N” “Takenate D-160N” “Takenate D-165N” “Takenate D-170HN” “Takenate D-178N” “Takenate 500” “Takenate 600” [Mitsui Chemicals, Inc.]; These compounds may be used alone or in combination of two or more.

As the peroxide, any radical active species can be used as long as it generates radical active species by heating or light irradiation to advance the crosslinking of the base polymer of the pressure-sensitive adhesive composition. However, in consideration of workability and stability. It is preferable to use a peroxide having a one-minute half-life temperature of 80 ° C. to 160 ° C., more preferably a peroxide having a 90 ° C. to 140 ° C.

Examples of the peroxide include di (2-ethylhexyl) peroxydicarbonate (1 minute half-life temperature: 90.6 ° C.), di (4-t-butylcyclohexyl) peroxydicarbonate (1 minute half-life). Temperature: 92.1 ° C.), di-sec-butyl peroxydicarbonate (1 minute half-life temperature: 92.4 ° C.), t-butyl peroxyneodecanoate (1 minute half-life temperature: 103.5 ° C.) ), T-hexyl peroxypivalate (1 minute half-life temperature: 109.1 ° C.), t-butyl peroxypivalate (1 minute half-life temperature: 110.3 ° C.), dilauroyl peroxide (half minute for 1 minute) Phase temperature: 116.4 ° C.), di-n-octanoyl peroxide (1 minute half-life temperature: 117.4 ° C.), 1,1,3,3-tetramethylbutylperoxy-2 Ethyl hexanoate (1 minute half-life temperature: 124.3 ° C.), di (4-methylbenzoyl) peroxide (1 minute half-life temperature: 128.2 ° C.), dibenzoyl peroxide (1 minute half-life temperature: 130 0.0 ° C.), t-butyl peroxyisobutyrate (1 minute half-life temperature: 136.1 ° C.), 1,1-di (t-hexylperoxy) cyclohexane (1 minute half-life temperature: 149.2 ° C.) ) And the like. Among them, since the crosslinking reaction efficiency is particularly excellent, di (4-t-butylcyclohexyl) peroxydicarbonate (1 minute half-life temperature: 92.1 ° C.), dilauroyl peroxide (1 minute half-life temperature: 116. 4 ° C.), dibenzoyl peroxide (1 minute half-life temperature: 130.0 ° C.), benzoyl peroxide (1 minute half-life temperature: 130.0 ° C.) and the like are preferably used.

The peroxide half-life is an index representing the decomposition rate of the peroxide, and means the time until the remaining amount of peroxide is reduced to half. The decomposition temperature for obtaining a half-life at an arbitrary time and the half-life time at an arbitrary temperature are described in a manufacturer catalog, for example, “Organic peroxide catalog 9th edition of Nippon Oil & Fats Co., Ltd.” (May 2003) ".

In addition, as a measuring method of the peroxide decomposition amount remaining after the reaction treatment, for example, it can be measured by HPLC (High Performance Liquid Chromatography). More specifically, for example, about 0.2 g of the pressure-sensitive adhesive composition after the reaction treatment is taken out, immersed in 10 mL of ethyl acetate, extracted by shaking at 25 ° C. and 120 rpm for 3 hours with a shaker, and then at room temperature. Leave for 3 days. Next, 10 mL of acetonitrile was added, shaken at 120 rpm at 25 ° C. for 30 minutes, and about 10 μL of the extract obtained by filtration through a membrane filter (0.45 μm) was injected into the HPLC for analysis. The amount of peroxide can be set.

The use amount (total amount) of the crosslinking agent is preferably 0.01 to 3 parts by weight, more preferably 0.02 to 2 parts by weight, and more preferably 0 to 100 parts by weight of the (meth) acrylic polymer. 0.03 to 1 part by weight is preferred. If the cross-linking agent is less than 0.01 parts by weight, the pressure-sensitive adhesive layer may be insufficiently cross-linked and the durability and adhesive properties may not be satisfied. On the other hand, if it exceeds 3 parts by weight, the pressure-sensitive adhesive layer becomes too hard. Durability may be reduced.

Furthermore, the pressure-sensitive adhesive composition of the present invention may contain other known additives such as a polyether compound of polyalkylene glycol such as polypropylene glycol, a colorant, a powder such as a pigment, a dye, Surfactant, plasticizer, silane coupling agent, tackifier, surface lubricant, leveling agent, softener, anti-aging agent, antioxidant, light stabilizer, UV absorber, polymerization inhibitor, inorganic or organic These fillers, metal powders, particles, foils, and the like can be added as appropriate according to the intended use. Moreover, you may employ | adopt the redox system which added a reducing agent within the controllable range.

<Adhesive layer and optical film with adhesive layer>
The pressure-sensitive adhesive layer of the present invention is preferably formed from the pressure-sensitive adhesive composition. In forming the pressure-sensitive adhesive layer with the pressure-sensitive adhesive composition, it is preferable to fully consider the influence of the crosslinking treatment temperature and the crosslinking treatment time as well as adjusting the amount of the entire crosslinking agent used.

The crosslinking treatment temperature and crosslinking treatment time can be adjusted depending on the crosslinking agent used. The crosslinking treatment temperature is preferably 170 ° C. or lower.

Further, such crosslinking treatment may be performed at the temperature during the drying step of the pressure-sensitive adhesive layer, or may be performed by providing a separate crosslinking treatment step after the drying step.

The crosslinking treatment time can be set in consideration of productivity and workability, but is usually about 0.2 to 20 minutes, preferably about 0.5 to 10 minutes.

In the optical film with an adhesive layer of the present invention, the adhesive layer is preferably formed on at least one side of the optical film. As a method for forming the pressure-sensitive adhesive layer, for example, a method in which the pressure-sensitive adhesive composition is applied to a release-processed separator, and the polymerization solvent is dried and removed to form a pressure-sensitive adhesive layer, and then transferred to an optical film, or The pressure-sensitive adhesive composition is applied to an optical film, and the polymerization solvent is dried and removed to form a pressure-sensitive adhesive layer on the optical film. In applying the pressure-sensitive adhesive, one or more solvents other than the polymerization solvent may be added as appropriate.

A silicone release liner is preferably used as the release-treated separator. In the step of applying the adhesive composition of the present invention on such a liner and drying to form a pressure-sensitive adhesive layer, a method for drying the pressure-sensitive adhesive is appropriately employed depending on the purpose. obtain. Preferably, a method of heating and drying the coating film is used. The heating and drying temperature is preferably 40 to 200 ° C., more preferably 50 to 180 ° C., and particularly preferably 70 to 170 ° C. By setting the heating temperature within the above range, an adhesive having excellent adhesive properties can be obtained.

Appropriate time can be adopted as the drying time. The drying time is preferably 5 seconds to 20 minutes, more preferably 5 seconds to 10 minutes, and particularly preferably 10 seconds to 5 minutes.

Also, an adhesive layer can be formed after forming an anchor layer or a surface treatment layer on the surface of the optical film, or after performing various easy adhesion treatments such as corona treatment and plasma treatment. Moreover, you may perform an easily bonding process on the surface of an adhesive layer.

As the method for forming the pressure-sensitive adhesive layer, various methods are used. Specifically, for example, by roll coat, kiss roll coat, gravure coat, reverse coat, roll brush, spray coat, dip roll coat, bar coat, knife coat, air knife coat, curtain coat, lip coat, die coater, etc. Examples thereof include an extrusion coating method.

The thickness of the pressure-sensitive adhesive layer is not particularly limited, but is preferably 5 to 100 μm, more preferably 5 to 50 μm, and further preferably 10 to 35 μm from the viewpoint of ensuring durability.

The surface resistance value of the pressure-sensitive adhesive layer surface is preferably 1 × 10 ⁸ to 1 × 10 ¹⁰ Ω / □ from the viewpoint of antistatic properties, and 2 × 10 ⁸ to 8 × 10 ⁹ Ω / □. It is preferably 3 × 10 ⁸ to 5 × 10 ⁹ Ω / □.

When the pressure-sensitive adhesive layer is exposed, the pressure-sensitive adhesive layer may be protected with a peeled sheet (separator) until practical use.

Examples of the constituent material of the separator include plastic films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester films, porous materials such as paper, cloth, and nonwoven fabric, nets, foam sheets, metal foils, and laminates thereof. Although an appropriate thin leaf body etc. can be mentioned, a plastic film is used suitably from the point which is excellent in surface smoothness.

The plastic film is not particularly limited as long as it can protect the pressure-sensitive adhesive layer. For example, a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, and a vinyl chloride co-polymer are used. Examples thereof include a polymer film, a polyethylene terephthalate film, a polybutylene terephthalate film, a polyurethane film, and an ethylene-vinyl acetate copolymer film.

The thickness of the separator is usually about 5 to 200 μm, preferably about 5 to 100 μm. For the separator, silicone type, fluorine type, long chain alkyl type or fatty acid amide type release agent, mold release and antifouling treatment with silica powder, coating type, kneading type, vapor deposition type, if necessary It is also possible to perform antistatic treatment such as. In particular, the release property from the pressure-sensitive adhesive layer can be further improved by appropriately performing a release treatment such as silicone treatment, long-chain alkyl treatment, and fluorine treatment on the surface of the separator.

In addition, the sheet | seat which carried out the peeling process used in preparation of the optical film with an adhesive layer can be used as a separator of an optical film with an adhesive layer as it is, and can simplify in a process surface.

Hereinafter, the optical film with an adhesive layer of the present invention will be described. In addition, the optical film with an adhesive layer has an optical film (for example, polarizing film) and an adhesive layer in this order. Moreover, it can have a surface treatment layer and an anchor layer.

<Optical film>
As the optical film, those used for forming an image display device such as a liquid crystal display device are used, and the type thereof is not particularly limited. For example, a polarizing film is mentioned as an optical film. A polarizing film having a transparent protective film on one or both sides of a polarizer is generally used.

The polarizer is not particularly limited, and various types can be used. Examples of polarizers include dichroic iodine and dichroic dyes on hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymer partially saponified films. Examples thereof include polyene-based oriented films such as those obtained by adsorbing substances and uniaxially stretched, polyvinyl alcohol dehydrated products and polyvinyl chloride dehydrochlorinated products. Among these, a polarizer composed of a polyvinyl alcohol film and a dichroic substance such as iodine is preferable. The thickness of these polarizers is not particularly limited, but is generally about 80 μm or less.

A polarizer obtained by dyeing the polyvinyl alcohol film with iodine and uniaxially stretching it is prepared, for example, by dyeing a polyvinyl alcohol film by immersing it in an aqueous solution of iodine and stretching it 3 to 7 times the original length. Can do. If necessary, it can be immersed in an aqueous solution of potassium iodide or the like which may contain boric acid, zinc sulfate, zinc chloride or the like. Further, if necessary, the polyvinyl alcohol film may be immersed in water and washed before dyeing. In addition to washing the polyvinyl alcohol film surface with stains and antiblocking agents by washing the polyvinyl alcohol film with water, the polyvinyl alcohol film is also swollen to prevent unevenness such as uneven coloring. is there. Stretching may be performed after dyeing with iodine, may be performed while dyeing, or may be dyed with iodine after stretching. The film can be stretched even in an aqueous solution of boric acid or potassium iodide or in a water bath.

Further, as the polarizer, a thin polarizer having a thickness of 10 μm or less can be used. From the viewpoint of thinning, the thickness is preferably 1 to 7 μm. Such a thin polarizer is preferable in that the thickness unevenness is small, the visibility is excellent, the dimensional change is small, the durability is excellent, and the thickness of the polarizing film can be reduced.

As the thin polarizer, typically, JP-A-51-069644, JP-A-2000-338329, WO2010 / 100917 pamphlet, PCT / JP2010 / 001460 specification, or Japanese Patent Application 2010. Examples thereof include thin polarizing films described in the specifications of -269002 and Japanese Patent Application No. 2010-263692. These thin polarizing films can be obtained by a production method including a step of stretching a polyvinyl alcohol-based resin (hereinafter also referred to as PVA-based resin) layer and a stretching resin base material in a laminated state and a step of dyeing. With this production method, even if the PVA-based resin layer is thin, it can be stretched without problems such as breakage due to stretching by being supported by the stretching resin substrate.

As the thin polarizing film, among the production methods including the step of stretching in the state of a laminate and the step of dyeing, WO2010 / 100917 pamphlet, PCT / PCT / PCT / JP 2010/001460 specification, or Japanese Patent Application No. 2010-269002 and Japanese Patent Application No. 2010-263692, the one obtained by a production method including a step of stretching in a boric acid aqueous solution is preferable. What is obtained by the manufacturing method including the process of extending | stretching in the air auxiliary before extending | stretching in the boric acid aqueous solution as described in Japanese Patent Application No. 2010-269002 and Japanese Patent Application No. 2010-263692 is preferable.

As the material constituting the transparent protective film, for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy and the like is used. Specific examples of such thermoplastic resins include cellulose resins such as triacetyl cellulose, polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth) acrylic resins, cyclic Examples thereof include polyolefin resins (norbornene resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. A transparent protective film is bonded to one side of the polarizer by an adhesive layer. On the other side, as a transparent protective film, (meth) acrylic, urethane-based, acrylurethane-based, epoxy-based, silicone A thermosetting resin such as a system or an ultraviolet curable resin can be used. One or more kinds of arbitrary appropriate additives may be contained in the transparent protective film. Examples of the additive include an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a release agent, a coloring inhibitor, a flame retardant, a nucleating agent, an ionic compound, a pigment, and a coloring agent. The content of the thermoplastic resin in the transparent protective film is preferably 50 to 100% by weight, more preferably 50 to 99% by weight, still more preferably 60 to 98% by weight, and particularly preferably 70 to 97% by weight. . When content of the said thermoplastic resin in a transparent protective film is 50 weight% or less, there exists a possibility that the high transparency etc. which a thermoplastic resin originally has cannot fully be expressed.

The adhesive used for laminating the polarizer and the transparent protective film is not particularly limited as long as it is optically transparent, and water-based, solvent-based, hot-melt-based, radical curable, and cationic curable types are used. However, water-based adhesives or radical curable adhesives are suitable.

In addition, as an optical film, it is used for forming a liquid crystal display device such as a reflection plate, an anti-transmission plate, a retardation film (including wavelength plates such as 1/2 and 1/4), a visual compensation film, and a brightness enhancement film. And an optical layer that may be formed. These can be used alone as an optical film, or can be laminated on the polarizing film for practical use to use one layer or two or more layers.

An optical film obtained by laminating the optical layer on a polarizing film can be formed by a method of laminating separately sequentially in the manufacturing process of a liquid crystal display device or the like. There is an advantage that the manufacturing process of a liquid crystal display device or the like can be improved because of excellent stability and assembly work. For the lamination, an appropriate adhesive means such as an adhesive layer can be used. When bonding the polarizing film and the other optical layer, their optical axes can be set at an appropriate arrangement angle in accordance with a target retardation characteristic or the like.

The optical film with an adhesive layer of the present invention can be preferably used for forming various image display devices such as a liquid crystal display device. The liquid crystal display device can be formed according to the conventional method. In other words, a liquid crystal display device is generally formed by appropriately assembling components such as a display panel such as a liquid crystal cell, an optical film with an adhesive layer, and an illumination system as necessary, and incorporating a drive circuit, etc. In this invention, there is no limitation in particular except the point which uses the optical film with an adhesive layer by this invention, According to the past. As the liquid crystal cell, any type such as a TN type, STN type, π type, VA type, IPS type, or the like can be used.

Forming an appropriate liquid crystal display device such as a liquid crystal display device in which an optical film with an adhesive layer is disposed on one side or both sides of a display panel such as the liquid crystal cell, or a lighting system using a backlight or a reflector. it can. In that case, the optical film with an adhesive layer by this invention can be installed in the one side or both sides of display panels, such as a liquid crystal cell. When optical films are provided on both sides, they may be the same or different. Furthermore, when forming a liquid crystal display device, for example, a single layer or a suitable layer of suitable components such as a diffusion layer, an antiglare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusion sheet, and a backlight, Two or more layers can be arranged.

<Anchor layer>
The anchor layer can be formed from various conductive agent compositions, and a conductive polymer can be used as the conductive agent that forms the anchor layer.

<Surface treatment layer>
The surface treatment layer can be provided on the side of the polarizing film where the anchor layer is not provided. The surface treatment layer can be provided on the transparent protective film used for the polarizing film, or can be provided separately from the transparent protective film. As the surface treatment layer, a hard coat layer, an antiglare treatment layer, an antireflection layer, an antisticking layer, and the like can be provided.

The surface treatment layer is preferably a hard coat layer. As a material for forming the hard coat layer, for example, a thermoplastic resin or a material that is cured by heat or radiation can be used. Examples of the material include radiation curable resins such as thermosetting resins, ultraviolet curable resins, and electron beam curable resins. Among these, an ultraviolet curable resin that can efficiently form a cured resin layer by a simple processing operation by a curing treatment by ultraviolet irradiation is preferable. Examples of these curable resins include polyesters, acrylics, urethanes, amides, silicones, epoxies, melamines, and the like, and these monomers, oligomers, polymers, and the like are included. Radiation curable resins, particularly ultraviolet curable resins are particularly preferred because of their high processing speed and low thermal damage to the substrate. Examples of the ultraviolet curable resin preferably used include those having an ultraviolet polymerizable functional group, and among them, those containing an acrylic monomer or oligomer component having 2 or more, particularly 3 to 6 functional groups. In addition, a photopolymerization initiator is blended in the ultraviolet curable resin.

Moreover, as the surface treatment layer, an antiglare treatment layer or an antireflection layer for the purpose of improving visibility can be provided. An antiglare treatment layer or an antireflection layer can be provided on the hard coat layer. The constituent material of the antiglare layer is not particularly limited, and for example, a radiation curable resin, a thermosetting resin, a thermoplastic resin, or the like can be used. As the antireflection layer, titanium oxide, zirconium oxide, silicon oxide, magnesium fluoride, or the like is used. The antireflection layer can be provided with a plurality of layers. In addition, examples of the surface treatment layer include a sticking prevention layer.

The surface treatment layer can be provided with conductivity by containing a conductive agent. As the conductive agent, the ionic compound or the like can be used.

<Other layers>
In the optical film with the pressure-sensitive adhesive layer of the present invention, in addition to the above-mentioned layers, an easy-adhesion layer is provided on the surface of the optical film (polarizing film) on which the anchor layer is provided, and various types such as corona treatment and plasma treatment are provided. Easy adhesion treatment can be performed.

Hereinafter, the present invention will be specifically described with reference to production examples and examples, but the present invention is not limited to these examples. In addition, all the parts and% in each example are based on weight. The room temperature standing conditions not specifically defined below are all 25 ° C.

<Theoretical value of glass transition temperature (Tg)>
The glass transition temperature (Tg) (° C.) of the acrylic polymer obtained in Examples and Comparative Examples is obtained by the following formula using the following literature values as the glass transition temperature Tgn (° C.) of the homopolymer of each monomer. It was.

Formula: 1 / (Tg + 273) = Σ [Wn / (Tgn + 273)]
[Wherein Tg (° C.) is the glass transition temperature of the copolymer, Wn (−) is the weight fraction of each monomer, Tgn (° C.) is the glass transition temperature of the homopolymer of each monomer, and n is the type of each monomer Represents. ]
Literature values:
Butyl acrylate (BA): -55 ° C
4-hydroxybutyl acrylate (4HBA): -32 ° C
Acrylic acid (AA): 106 ° C
Phenoxyethyl acrylate (PEA): -22 ° C
N-vinyl-pyrrolidone (NVP): 54 ° C
N-acryloylmorpholine (ACMO): 145 ° C

[Example 1]
(Production of thin polarizing film)
In order to produce a thin polarizing layer, first, a laminate in which a 9 μm-thick polyvinyl alcohol (PVA) layer is formed on an amorphous polyethylene terephthalate (PET) substrate is stretched by air-assisted stretching at a stretching temperature of 130 ° C. Next, a colored laminate is produced by dyeing the stretched laminate, and further the colored laminate is amorphous so that the total draw ratio is 5.94 times by stretching in boric acid water at a stretching temperature of 65 ° C. An optical film laminate comprising a 4 μm thick PVA layer stretched together with a PET substrate was produced. The PVA molecules in the PVA layer formed on the amorphous PET substrate by such two-stage stretching are oriented in the higher order, and the iodine adsorbed by the dyeing is oriented in the one direction as the polyiodine ion complex. It was possible to produce an optical film laminate including a PVA layer having a thickness of 4 μm, which constitutes a highly functional polarizing layer. Furthermore, after applying a saponified 40 μm thick triacetyl cellulose film while applying a polyvinyl alcohol-based adhesive on the surface of the polarizing layer of the optical film laminate, the amorphous PET substrate was peeled off, A thin polarizing film using a thin polarizing layer was produced.

(Preparation of acrylic polymer 1)
A monomer mixture containing 99 parts by weight of butyl acrylate (BA) and 1 part by weight of 4-hydroxybutyl acrylate (4HBA) was charged into a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser. . Furthermore, with respect to 100 parts by weight of the monomer mixture (solid content), 0.1 part by weight of 2,2′-azobisisobutyronitrile as a polymerization initiator was charged together with ethyl acetate, and nitrogen gas was added while gently stirring. After introducing and purging with nitrogen, a polymerization reaction was carried out for 7 hours while maintaining the liquid temperature in the flask at around 60 ° C. Thereafter, ethyl acetate was added to the resulting reaction solution to adjust the solid content concentration to 30%. A solution of acrylic polymer 1 having a glass transition temperature (Tg) of −38 ° C. was prepared.

(Preparation of acrylic adhesive solution)
With respect to 100 parts by weight of the solid content of the acrylic polymer 1 solution, 1-ethyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name “ELEXEL AS”) is used as the ionic compound. -110 ") and 6 parts by weight of trimethylolpropane xylylene diisocyanate (trade name“ Takenate D110N ”, manufactured by Mitsui Chemicals) and dibenzoyl peroxide (trade name). "Niper BMT40SV" (manufactured by NOF Corporation) 0.3 parts by weight, as a thiol-based silane coupling agent, a methyl group and mercapto group-containing alkoxysilyl resin (trade name "X-41-1810", manufactured by Shin-Etsu Chemical Co., Ltd.) 0.2 parts by weight, acetoacetate as acetoacetyl group-containing silane coupling agent An acrylic system containing 0.2 part by weight of a ru group-containing silane coupling agent (trade name “A-100”, manufactured by Soken Chemical Co., Ltd.) and 0.3 part by weight of an antioxidant (Irganox 1010 from BASF). An adhesive solution was prepared.

(Preparation of pressure-sensitive adhesive layer and polarizing film with pressure-sensitive adhesive layer)
Next, the acrylic adhesive 1 solution was applied to one side of a polyethylene terephthalate film (separator film: manufactured by Mitsubishi Chemical Polyester Film Co., Ltd., MRF38) treated with a silicone release agent, and the thickness of the adhesive layer after drying was 20 μm. And then dried at 155 ° C. for 1 minute to form an adhesive layer on the surface of the separator film. The said adhesive layer was transcribe | transferred to the surface which does not have the transparent protective film of the said polarizing film, and produced the polarizing film with an adhesive layer.

[Example 2]
Example 1 except that 2 parts by weight of 1-ethyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name “ELEXEL AS-110”) was blended as the ionic compound. In the same manner, a polarizing film with a pressure-sensitive adhesive layer was produced.

[Example 3]
(Preparation of acrylic polymer 2)
In a four-necked flask equipped with a stirring blade, thermometer, nitrogen gas inlet tube, and condenser, 80.3 parts by weight of butyl acrylate, 16 parts by weight of phenoxyethyl acrylate, 3 parts by weight of N-vinyl-2-pyrrolidone (NVP) A monomer mixture containing 0.2 part by weight of acrylic acid and 0.5 part by weight of 4-hydroxybutyl acrylate was charged. Furthermore, with respect to 100 parts by weight of the monomer mixture (solid content), 0.1 part by weight of 2,2′-azobisisobutyronitrile as a polymerization initiator was charged together with 100 parts by weight of ethyl acetate, while gently stirring. After introducing nitrogen gas and replacing with nitrogen, the polymerization temperature is kept at around 55 ° C for 8 hours to prepare a solution of acrylic polymer 2 having a glass transition temperature (Tg) of -24 ° C. did.

(Preparation of acrylic adhesive solution)
With respect to 100 parts by weight of the solid content of the acrylic polymer 2 solution, as an ionic compound, 1-ethyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide (made by Daiichi Kogyo Seiyaku Co., Ltd., trade name “ELEXEL AS”) -110 ") 6 parts by weight, and further, 0.17 parts by weight of an isocyanate crosslinking agent (trade name" Takenate D-160N ", trimethylolpropane hexamethylene diisocyanate, manufactured by Mitsui Chemicals, Inc.) as a crosslinking agent, benzoyl par 0.25 parts by weight of oxide (BPO: Niper BMT manufactured by NOF Corporation), 0.2 parts by weight of silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd .: X-41-1810), silane coupling agent containing acetoacetyl group ( (Product name "A-100", manufactured by Soken Chemical Co., Ltd.) It was prepared.

[Example 4]
Example 2 except that 8 parts by weight of 1-ethyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name “ELEXEL AS-110”) was blended as the ionic compound. In the same manner, a polarizing film with a pressure-sensitive adhesive layer was produced.

[Example 5]
(Preparation of acrylic polymer 3)
In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser, 100 parts by weight of butyl acrylate, 7 parts by weight of N-acryloylmorpholine, 3 parts by weight of acrylic acid, 0.3 hydroxy 2-hydroxybutyl acrylate Part by weight, 0.12 part by weight of 2,2′-azobisisobutyronitrile as a polymerization initiator and 200 parts by weight of ethyl acetate were charged, and nitrogen substitution was carried out by introducing nitrogen gas while gently stirring. The polymerization temperature was maintained at around 55 ° C. for 8 hours to carry out a polymerization reaction to prepare an acrylic polymer 3 solution having a glass transition temperature (Tg) of −15 ° C.

(Preparation of acrylic adhesive solution)
With respect to 100 parts by weight of the solid content of the acrylic polymer 3 solution, as an ionic compound, 1-ethyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name “ELEXEL AS”) -110 ") 6 parts by weight, and as a crosslinking agent, a polyisocyanate-based crosslinking agent composed of a trimethylolpropane adduct of tolylene diisocyanate (trade name" Coronate L ", manufactured by Tosoh Corporation) 0.15 weight An acrylic pressure-sensitive adhesive solution containing 0.25 parts by weight of benzoyl peroxide (BPO: Niper BMT manufactured by NOF Corporation) was prepared.

[Comparative Example 1]
Example 3 with the exception that 3 parts by weight of ethylmethylpyrrolidinium bis (trifluoromethanesulfonyl) imide (EMPTFSI, manufactured by Mitsubishi Materials Corporation, trade name “P1,2 · N111”) was blended as the ionic compound. Similarly, a polarizing film with an adhesive layer was produced.

[Comparative Example 2]
Example 3 except that 5 parts by weight of 1-octyl-4-methylpyridinium bis (fluorosulfonyl) imide (MOPyFSI, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name “ELEXEL AS-804”) was blended as the ionic compound. In the same manner, a polarizing film with a pressure-sensitive adhesive layer was produced.

[Comparative Example 3]
0.7 parts by weight of lithium bis (trifluoromethanesulfonyl) imide (LiTFSI, manufactured by Tokyo Chemical Industry Co., Ltd.) as an ionic compound, ethylmethylpyrrolidinium bis (trifluoromethanesulfonyl) imide (EMPTFSI, manufactured by Mitsubishi Materials Corporation), A polarizing film with a pressure-sensitive adhesive layer was produced in the same manner as in Example 1 except that 1 part by weight of the trade name “P1, 2 · N111”) was blended.

[Method for producing surface protective film used for evaluation of white unevenness]
(Preparation of acrylic polymer (A))
In a four-necked flask equipped with a stirring blade, thermometer, nitrogen gas inlet tube, and condenser, 100 parts by weight of 2-ethylhexyl acrylate (2EHA), 10 parts by weight of 4-hydroxybutyl acrylate (4HBA), acrylic acid (AA) 0 .02 parts by weight, 0.22 parts by weight of 2,2′-azobisisobutyronitrile and 157 parts by weight of ethyl acetate as a polymerization initiator were charged, nitrogen gas was introduced while gently stirring, and the liquid temperature in the flask was Was maintained at around 65 ° C. for 6 hours to prepare an acrylic polymer (A) solution (40% by weight). The glass transition temperature (Tg) of the acrylic polymer (A) was −67 ° C.

(Preparation of acrylic adhesive solution)
The acrylic polymer (A) solution (40% by weight) is diluted with ethyl acetate to 20% by weight, and 500 parts by weight (100 parts by weight of solid content) of this solution is an organopolysiloxane having an oxyalkylene chain as a silicone component. (Trade name “KF-353”, manufactured by Shin-Etsu Chemical Co., Ltd.) diluted with ethyl acetate to 10% 2 parts by weight (solid content 0.2 parts by weight), an alkali metal salt as an antistatic agent, lithium bis 15 parts by weight (solid content 0.15 parts by weight) of a solution obtained by diluting (trifluoromethanesulfonyl) imide (LiN (CF ₃ SO ₂ ) ₂ : LiTFSI, manufactured by Tokyo Chemical Industry Co., Ltd.) with ethyl acetate to 1%, as a crosslinking agent Isocyanurate of hexamethylene diisocyanate, a trifunctional isocyanate compound (trade name “Coronate HX”, manufactured by Tosoh Corporation), 3.5 weight (Solid content 1.75 parts by weight) 1,3-bis (isocyanatomethyl) cyclohexane (trade name “Takenate 600” manufactured by Mitsui Chemicals, Inc.) which is a bifunctional isocyanate compound 0.3 parts by weight (solid content 0. 3 parts by weight), 2 parts by weight of dibutyltin dilaurate (1% by weight ethyl acetate solution) as a crosslinking catalyst (0.02 parts by weight of solid content), 0.5 part by weight of an acrylic oligomer produced by the following preparation method, Mixing and stirring were performed to prepare an acrylic pressure-sensitive adhesive solution.

(Preparation of acrylic oligomer)
In a four-necked flask equipped with a stirring blade, thermometer, nitrogen gas inlet tube, cooler, and dropping funnel, 100 parts by weight of toluene, dicyclopentanyl methacrylate (DCPMA) (trade name “FA-513M”, Hitachi Chemical Co., Ltd. 60 parts by weight), methyl methacrylate (MMA) 40 parts by weight, and 3.5 parts by weight of methyl thioglycolate as a chain transfer agent were added. After stirring for 1 hour at 70 ° C. in a nitrogen atmosphere, 0.2 part by weight of 2,2′-azobisisobutyronitrile was added as a polymerization initiator and reacted at 70 ° C. for 2 hours. After making it react at 80 degreeC for 4 hours, it was made to react at 90 degreeC for 1 hour, and the acrylic oligomer was obtained. The acrylic oligomer had a glass transition temperature (Tg) of 144 ° C.

[Preparation of antistatic film]
Antistatic agent by diluting 10 parts by weight of antistatic agent (manufactured by Solvex, Microsolver RMd-142, mainly composed of tin oxide and polyester resin) with a mixed solvent of 30 parts by weight of water and 70 parts by weight of methanol An agent solution was prepared.

The obtained antistatic agent solution was applied onto a polyethylene terephthalate (PET) film (thickness: 38 μm) using a Meyer bar and dried at 130 ° C. for 1 minute to remove the solvent and remove the antistatic layer (thickness). Thickness: 0.2 μm) to form an antistatic film.

[Production of surface protective film]
The acrylic pressure-sensitive adhesive solution was applied to the surface opposite to the antistatic surface of the antistatic film and heated at 130 ° C. for 2 minutes to form a pressure-sensitive adhesive layer having a thickness of 15 μm. Next, the surface of the pressure-sensitive adhesive layer was bonded with a silicone-treated surface of a polyethylene terephthalate film (thickness 25 μm) that had been subjected to silicone treatment on one side to produce a surface protective film.

For the polarizing films with pressure-sensitive adhesive layers obtained in the above examples and comparative examples, the following surface resistance and white unevenness were evaluated. The evaluation results are shown in Table 3.

<Measurement of the surface resistance value of the pressure-sensitive adhesive layer surface>
The separator film of the polarizing film with the pressure-sensitive adhesive layer obtained in Examples and Comparative Examples was peeled off and left for 1 minute at room temperature (25 ° C.), and then the surface resistance value (Ω / □) of the pressure-sensitive adhesive layer surface. Was measured using MCP-HT450 manufactured by Mitsubishi Chemical Analytech. The antistatic property was evaluated from the surface resistance value.
The surface resistance value on the surface of the pressure-sensitive adhesive layer is preferably 1 × 10 ⁸ to 1 × 10 ¹⁰ Ω / □ from the viewpoint of antistatic properties, and is 2 × 10 ⁸ to 8 × 10 ⁹ Ω / □. And more preferably 3 × 10 ⁸ to 5 × 10 ⁹ Ω / □.

<White color disappearance time of liquid crystal panel (room temperature (25 ° C))>
The said surface protection film was bonded together on the surface of the polarizing film of the polarizing film with an adhesive layer obtained by the Example and the comparative example using the hand roller. After that, it is cut into a size of 150 mm × 100 mm, the separator film is peeled off, and the liquid crystal panel is attached to form a liquid crystal panel. This panel is placed on a backlight having a luminance of 10,000 cd at room temperature (25 ° C.), and the above surface protection The film was peeled off from the surface of the polarizing film at a speed of 1 m / second to generate static electricity, thereby causing disorder in the alignment of the liquid crystal. The recovery time (seconds) of display failure due to the orientation failure was measured by visual observation, and white unevenness was evaluated.
The display failure recovery time is preferably 10 seconds or shorter, and more preferably 5 seconds or shorter. The white unevenness was evaluated according to the following criteria. In addition, it was judged that there was no problem in practical use except for x.
◎: Recovery (disappearance) time is less than 5 seconds ○: Recovery (disappearance) time is less than 10 seconds △: Recovery (disappearance) time is less than 10-30 seconds ×: Recovery (disappearance) time is 30 seconds or more

<White panel disappearance time (low temperature)>
The said surface protection film was bonded together on the surface of the polarizing film of the polarizing film with an adhesive layer obtained by the Example and the comparative example using the hand roller. Thereafter, it is cut into a size of 150 mm × 100 mm, the separator film is peeled off, and the liquid crystal cell is attached to form a liquid crystal panel, and this panel is cooled to −20 ° C. (low temperature) (MG-322 manufactured by ESPEC). ) For 15 minutes.
Immediately after taking out to room temperature (25 ° C), this panel is placed on a backlight having a luminance of 10000 cd with a surface temperature of -5 ° C, and the surface protection film is peeled off from the surface of the polarizing film at a speed of 1 m / sec. The liquid crystal orientation was disturbed by generating. The recovery time (seconds) of display failure due to the orientation failure was measured by visual observation, and white unevenness was evaluated.
The display failure recovery time is preferably 10 seconds or shorter, and more preferably 5 seconds or shorter. The white unevenness was evaluated according to the following criteria. In addition, it was judged that there was no problem in practical use except for x.
◎: Recovery (disappearance) time is less than 5 seconds ○: Recovery (disappearance) time is less than 10 seconds △: Recovery (disappearance) time is less than 10-30 seconds ×: Recovery (disappearance) time is 30 seconds or more

 
 

 

Abbreviations in Table 1 and Table 2 are as follows.
BA: butyl acrylate PEA: phenoxyethyl acrylate NVP: N-vinyl-pyrrolidone AA: acrylic acid 4HBA: 4-hydroxybutyl acrylate ACMO: N-acryloylmorpholine AS110: 1-ethyl-3-methylimidazolium bis (fluorosulfonyl) imide (Daiichi Kogyo Seiyaku Co., Ltd., trade name: Elexcel AS-110), ionic liquid (melting point: −12.9 ° C.)
EMPTFSI: Ethylmethylpyrrolidinium bis (trifluoromethanesulfonyl) imide (manufactured by Mitsubishi Materials Corporation, trade name: P1, N111), ionic solid (melting point: 90 ° C.)
MOPyFSI: 1-octyl-4-methylpyridinium bis (fluorosulfonyl) imide (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name: Elexel AS-804), ionic liquid (melting point: -3.1 ° C.)
LiTFSI: Lithium bis (trifluoromethanesulfonyl) imide (manufactured by Tokyo Chemical Industry Co., Ltd., LiN (CF ₃ SO ₂ ) ₂ ), alkali metal salt (melting point: 232 ° C.)

Note) “E + 08” in Table 3 indicates “1 × 10 ⁸ ”.

From the evaluation results of Table 3 above, in all examples, by using an ionic compound having a desired melting point, it is possible to suppress white unevenness in a low temperature environment, and polarization with an adhesive layer excellent in antistatic properties. It was confirmed that a film (optical film) was obtained. On the other hand, in the comparative example, since the melting point of the ionic compound was out of the desired range, it was confirmed that white unevenness under a low temperature environment could not be suppressed and the antistatic property could not be satisfied.

The optical film with the pressure-sensitive adhesive layer formed using the pressure-sensitive adhesive composition disclosed herein can impart antistatic properties in a wide temperature range including under a low-temperature environment. The effect of preventing white unevenness more stable against environmental changes in the temperature range can be imparted. In addition, it is possible to suppress the generation of static electricity over a wide temperature range even in the use of manufacturing process materials and protective films for materials such as electronic parts and semiconductors that are damaged or defective due to static electricity. In addition, when the pressure-sensitive adhesive composition disclosed herein is used as a constituent member such as a bonding material, the generated static electricity can be released, so that failure and failure of electronic components and semiconductors can be prevented.

Claims (5)

1. A pressure-sensitive adhesive composition comprising a (meth) acrylic polymer and an ionic compound having a melting point of −5 ° C. or lower.
2. The pressure-sensitive adhesive composition according to claim 1, wherein the electrical conductivity of the ionic compound at 25 ° C is 10 mS / cm or more.
3. The ionic compound is an ionic liquid;
   The ionic liquid is an organic cation-anion salt;
   The pressure-sensitive adhesive composition according to claim 1 or 2, wherein the anion is a bis (fluorosulfonyl) imide anion and / or a bis (trifluoromethanesulfonyl) imide anion.
4. A pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition according to any one of claims 1 to 3.
5. An optical film with an adhesive layer, wherein the adhesive layer according to claim 4 is formed on at least one side of the optical film.