TW202000826A - Adhesive sheet having an adhesive layer capable of realizing high antistatic performance and durability under severe conditions, and suppressing color unevenness and white spot phenomenon generated on a display screen - Google Patents

Abstract

An object of the present invention is to provide an adhesive sheet for sticking polarizing plates, which has an adhesive layer capable of realizing high antistatic performance and durability under severe conditions, and suppressing color unevenness and white spot phenomenon generated on a display screen. In the adhesive sheet for sticking polarizing plates of the present invention, the adhesive layer is composed of an adhesive composition containing an acrylic copolymer (A), a curing agent, and an antistatic agent (C), wherein (C) is a compound containing fluorine or silicon (except for the case of containing the compound represented by M<SP>+</SP>[(FSO2) 2N]<SP>-</SP> where M is an alkali metal), and is added with an amount of more than 3.5 parts and less than 10 parts relative to 100 parts of (A); (A) is a monomer containing more than 15% and less than 50% of the monomer represented by the general formula (1) in a monomer composition, and having a reactive functional group based on 0.01-5 parts; and the surface resistance value of the adhesive layer is 4.0×10<SP>9</SP> [OMEGA]/[SQUARE] or less.

Description

Adhesive sheet

The invention relates to an adhesive sheet, which is used for attaching a polarizing plate used for optical parts such as liquid crystal cells of a liquid crystal display device, and has a release film or release paper and an adhesive layer.

In recent years, since liquid crystal display devices have achieved weight reduction and thinning, they are widely used as displays for vehicle mounting, outdoor counters, and personal computers, or as display devices for televisions, etc., and the demand for them has been increasing. Along with this, the usage environment of the liquid crystal display device is also diversified, and it is necessary to cope with very severe conditions regardless of indoor and outdoor. Here, the liquid crystal display device is attached to the outer surface of the glass substrate of the liquid crystal cell (the liquid crystal component oriented in a predetermined direction is sandwiched by two glass substrates), and is adhered via an adhesive layer formed of an optical adhesive composition A polarizer, a laminate of a polarizer and a retardation plate, etc. (hereinafter referred to as a "polarizer").

The above-mentioned polarizing plate generally has a three-layer structure in which both sides of a polarizer composed of a polyvinyl alcohol-based material are sandwiched by a triethyl acetyl cellulose-based protective film, but the characteristics of these materials lack dimensional stability . In addition, since the polarizing plate is formed by extension, it is easy to expand and contract due to heat and humidity. Therefore, in the liquid crystal display device, if the adhesive layer used in the buildup cannot absorb and relax the internal stress caused by the expansion and contraction of the polarizing plate, the distribution of the residual stress acting on the polarizing plate becomes uneven. Then, if the stress is particularly concentrated on its peripheral portion, as a result, the peripheral edge of the display portion of the liquid crystal display device becomes brighter or darker than the center, and color unevenness and whitening occur on the liquid crystal display surface.

In addition to the above-mentioned technical issues, the adhesive layer constituting the polarizing plate also needs to peel off the release film or release paper attached to the adhesive surface when sticking, but static electricity occurs during peeling, and there is a problem The issue of the impact of functional materials stacked through the adhesive layer. Specifically, for example, if static electricity is generated when the release film is peeled off from the adhesive layer provided on the polarizing plate, the static electricity affects the liquid crystal layer inside the liquid crystal cell and causes a defect. In addition, the liquid crystal display device with a touch sensor will cause adverse effects such as erroneous operation of the capacitance sensor. As a means of suppressing the generation of static electricity when peeling off the release film, there is a method of imparting antistatic properties to the adhesive layer. On the other hand, as described below, the level of antistatic performance required in recent years has been exceptionally higher than conventional knowledge.

In order to improve antistatic performance, antistatic agents must be added. However, if the added amount is too large, the cohesive force of the adhesive decreases, and especially under severe durability conditions, the adhesive layer tends to peel or foam. Therefore, it is very difficult to make the formed adhesive layer have durability that can be satisfied even under severe endurance conditions (hereinafter referred to as "durability under severe conditions"), and to suppress the display surface of the display device Color unevenness and white space phenomenon occur, and it is difficult to make it exhibit superior antistatic performance when peeling the above-mentioned release film, so far such an adhesive layer has not been realized.

In particular, liquid crystal display devices have been used in a wide range of fields in recent years. Therefore, in in-vehicle applications such as car navigation, the temperature of the interior of the car that becomes a closed space becomes extremely high, and the use environment is also diverse. Durability under more severe conditions in the past. Therefore, there has been a problem that the durability of adhesives used in liquid crystal display devices such as TVs mounted at room temperature is insufficient.

Regarding the adhesives used in liquid crystal display devices having these problems, various proposals have been made so far. For example, Patent Document 1 proposes an adhesive composition containing: an unsaturated monomer containing (meth)acrylate and an unsaturated monomer having an aromatic ring (2-phenoxyethyl acrylate) and an unsaturated monomer having a polar functional group The copolymer obtained from the monomer mixture of the polymer; an ionic compound (antistatic agent) that is solid at room temperature; and a crosslinking agent. In addition, Patent Document 2 proposes an adhesive composition containing (meth)acrylic polymer containing alkyl (meth)acrylate and aromatic ring-containing alkyl (meth)acrylate as monomer units (A); and alkali metal salts (B). Furthermore, Patent Document 3 proposes an adhesive composition comprising: an alicyclic structure-containing monomer (a1), an aromatic ring-containing monomer (a2), and an oxyalkylene group-containing monomer (a3) (Meth)acrylate copolymer (A) as a monomer unit constituting the polymer; and a crosslinking agent (B).

Further, as an antistatic agent, there has been proposed the use of KN (FSO _{2) 2,} etc. by the ^{_{M + [(FSO 2) 2}} N] - specific alkali metal salts as represented by the adhesive composition of an antistatic agent, in In the examples, it is described that the surface resistance value of the adhesive sheet using the adhesive composition is 4.0×10 ⁹ Ω/□ or less.

[Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2010-066755

[Patent Document 2] Japanese Patent Laid-Open No. 2016-028287

[Patent Document 3] Japanese Patent Laid-Open No. 2017-134134

[Patent Document 4] Korean Patent Publication No. 10-2010-0018414

However, according to the inspection by the inventors of the present application, the adhesive composition proposed in Patent Document 1 does not have sufficient adhesive layer to achieve the durability required under the severe conditions mentioned above in recent years and to provide a high level of Both antistatic properties. In addition, although the adhesive composition proposed in Patent Document 2 or the adhesive composition proposed in Patent Document 3 is obtained with an adhesive layer having excellent antistatic properties, it has not been satisfied that it has been placed under severe use in recent years. "Durability under severe conditions" as required by the environment. Although the surface resistance of the adhesive sheet formed by the adhesive composition described in Patent Document 4 is 4.0×10 ⁹ Ω/□ or less, its durability effect still stops at 60°C and 90% relative humidity. The observation of the peeling phenomenon, bubble generation and light leakage generated after the furnace was placed for 300 hours has not yet achieved the stricter durability that satisfies the problem of the present invention.

Therefore, an object of the present invention is to provide an adhesive sheet that can be used to form an adhesive layer that constitutes a polarizing plate that is widely used in a wide range of fields, has superior antistatic performance that has not been achieved so far, and has severe conditions Under the durability, and can suppress the uneven color and white space that occur on the display screen. In particular, the present invention aims to provide an adhesive composition for forming the adhesive layer of the above-mentioned useful adhesive sheet.

The above object is achieved by the following invention. That is, the present invention provides the following inventions regarding an adhesive sheet.

[1] An adhesive sheet comprising a release film or a release paper and an adhesive layer, which is an adhesive sheet for polarizing plate sticking, characterized in that the adhesive layer contains at least acrylic copolymer An adhesive composition composed of a combination (A), a hardener (B), and an antistatic agent (C); the above antistatic agent (C) is a compound containing either fluorine or silicon in its structure (where, M is an alkali metal contained by the sum ^{_{M + [(FSO 2) 2}} N] - except in the case of the compound represented by), with respect to the acrylic of copolymer (a) 100 parts by mass, 3.5 parts by mass or more and less than Add in a range of 10 parts by mass; the acrylic copolymer (A) monomer composition should contain at least 50% by mass and less than 85% by mass of the ethylenically unsaturated monomer (a1) with no reactive functional group. 1 kind, and containing more than 15% by mass and 50% by mass or less of at least one kind of monomer (a2) represented by the following general formula (1); and, with respect to the above-mentioned monomer (a1) and the above-mentioned monomer ( a2) A total of 100 parts by mass, based on 0.01 parts by mass or more and 5 parts by mass or less, by copolymerizing at least one type of monomer containing an ethylenically unsaturated monomer (a3) with a reactive functional group; the above adhesion The surface resistance of the agent layer is below 4.0×10 ⁹ Ω/□;

(In general formula (1), R ¹ represents a hydrogen atom or a methyl group, R ² represents any one of a hydrogen atom, an alkyl group, an aralkyl group, or an aryl group, and n represents any integer of 2 to 9.)

Preferred embodiments of the present invention include the following.

[2] The adhesive sheet according to [1], wherein the reactive functional group of the ethylenically unsaturated monomer (a3) having a reactive functional group is selected from the group consisting of hydroxyl group, carboxyl group, epoxypropyl group and nitrogen-containing At least any one of the groups formed by the basis.

[3] The adhesive sheet according to [1] or [2], wherein the hardener (B) contains an isocyanate compound, and the amount of use thereof is 100 parts by mass relative to the acrylic copolymer (A) 0.01 parts by mass or more and 10 parts by mass or less.

[4] The adhesive sheet according to any one of [1] to [3], wherein the adhesive composition further contains a silane coupling agent (D).

According to the present invention, there is provided an adhesive sheet comprising a release film or a release paper (hereinafter referred to as "release film") and an adhesive layer, which is an adhesive sheet for attaching a polarizing plate. It forms an adhesive layer that has unprecedented antistatic performance and durability under severe conditions. When used in image display parts, it can suppress the occurrence of color unevenness and whitening. In addition, according to the present invention, there is provided an adhesive composition which can be used to form the above-mentioned adhesive layer having superior performance, which can form an excellent antistatic performance that has not been achieved so far, and durability under severe conditions. Adhesive layer.

Next, preferred embodiments for implementing the present invention will be listed, and the present invention will be described in more detail. In addition, the term "(meth)acrylic acid" in the patent application scope and specification of the present invention means both "acrylic acid" and "methacrylic acid"; in addition, the term "(meth)acrylate" means Refers to both "acrylate" and "methacrylate".

The adhesive sheet of the present invention is used for attaching a polarizing plate to an optical component such as a liquid crystal cell of a liquid crystal display device, and the adhesive layer constituting the adhesive sheet is composed of at least an acrylic copolymer (A) and a hardener (B) An adhesive composition containing an antistatic agent (C) as a constituent and further containing a silane coupling agent (D) as needed. Furthermore, the adhesive sheet of the present invention is composed of the monomer of the acrylic copolymer (A) contained in the adhesive composition forming the adhesive layer, so as to contain the above general formula (1) in a specific range For the specified unique monomer (a2), the adhesive layer formed by the adhesive composition shows that the surface resistance value is less than 5.0×10 ⁹ Ω/□, and furthermore, it is unachievable until 4.0×10 ⁹ Ω/□ or less Superior antistatic performance (hereinafter referred to as "superior antistatic performance"), and shows durability under severe conditions, realizing superior performance that cannot be achieved with conventional technology. Each of these components constituting the present invention will be described below.

[Acrylic copolymer (A)]

The acrylic copolymer (A)-based monomer is composed of at least one kind of ethylenically unsaturated monomer (a1) containing no reactive functional group of 50% by mass or more and less than 85% by mass, and contains the following general formula (1) At least one type of monomer (a2) shown is a copolymer having a composition within a range of more than 15% by mass and 50% by mass or less. In addition, it contains a reactive functional group based on 100 parts by mass of the monomer (a1) and the monomer (a2) in an amount within the range of 0.01 parts by mass or more and 5 parts by mass or more. Acrylic copolymer obtained by copolymerizing at least one kind of monomer composition of saturated monomer (a3).

(In general formula (1), R ¹ represents a hydrogen atom or a methyl group, R ² represents any one of a hydrogen atom, an alkyl group, an aralkyl group, or an aryl group, and n represents any integer from 2 to 9.)

(Single (a1))

Ethylene unsaturated monomer (a1) without reactive functional group (hereinafter also abbreviated as "(a1) component"), which is based on monomer (a1) and monomer (a2) of acrylic copolymer (A) In the monomer composition, it is used at a ratio of 50% by mass or more and less than 85% by mass. If the proportion of (a1) component is less than 50% by mass, the adhesiveness to the substrate or the flexibility of the adhesive layer decreases when the adhesive layer is formed, peeling or floating from the substrate occurs and cannot be obtained Full durability. On the other hand, if the ratio of (a1) component is 85% by mass or more, the adhesion to the substrate is insufficient, and the adhesive layer foams under severe durability conditions. Also, the antistatic performance is insufficient.

Examples of the component (a1) include (meth)acrylate monomers having 1 to 18 carbon atoms. Specific examples include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, (meth)acrylic acid Alkyl (meth)acrylates such as 2-ethylhexyl ester, octyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, lauryl (meth)acrylate and the like. These can be used alone or in combination of two or more.

(Single (a2))

The acrylic copolymer (A) is based on the monomer composition of the monomer (a1) and the monomer (a2), and contains the monomer (a2) represented by the following general formula (1) (hereinafter also abbreviated as "( a2) Component") Synthesized at a ratio of more than 15% by mass and 50% by mass or less. Since the above-mentioned monomer composition contains the component (a2) within the above range, in the adhesive layer formed by using an antistatic agent (C) described later, the durability under severe conditions that cannot be achieved by the conventional technology can be taken into account. And excellent antistatic performance. That is, if the component (a2) is outside the above range, it will be difficult to achieve an excellent antistatic performance and durability under severe conditions in the formed adhesive layer.

(In general formula (1), R ¹ represents a hydrogen atom or a methyl group, R ² represents any one of a hydrogen atom, an alkyl group, an aralkyl group, or an aryl group, and n represents any integer from 2 to 9.)

Specific components (a2) include, for example, phenoxydiethylene glycol acrylic acid, phenoxytriethylene glycol acrylic acid, and nonylphenoxypolyethylene glycol acrylate. These can be used alone or in combination of two or more.

(Single (a3))

The monomer composition of the synthetic acrylic copolymer (A) is, in addition to the above-mentioned (a1) component and (a2) component, with respect to the total of 100 parts by mass of the (a1) component and (a2) component, 0.01 parts by mass or more And it is comprised by adding the ethylenically unsaturated monomer (a3) with a reactive functional group (hereinafter also simply referred to as "(a3) component") in an amount of 5 parts by mass or less. More preferably, it is 0.01 mass part or more and 3 mass parts or less. The coating film-forming resin constituting the adhesive composition of the present invention can form an adhesive layer with superior durability by containing the component (a3) which reacts with the hardener within the above range. Examples of the reactive functional group include a hydroxy group, a glycidyl group, and an amide group. Among them, an ethylenically unsaturated monomer having a carboxyl group is preferably used. In the monomer composition of the acrylic copolymer (A), with respect to the total of 100 parts by mass of the (a1) component and the (a2) component, if the (a3) component is less than the above range, the cohesive force of the adhesive layer decreases, and Under the severe durability conditions of the subject of the present invention, foaming of the adhesive layer occurs; if it exceeds the above range, the adhesiveness of the adhesive layer to the substrate is impaired, and there is a risk of peeling.

Examples of the component (a3) include hydroxyl-containing (meth)acrylate monomers such as hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate, (meth)acrylic acid, (meth) Carboxy-containing monomers such as β-carboxyethyl acrylate, glycidyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate glycidyl ether-containing monomers, (meth) Acrylate-based monomers such as acrylamide and dimethylaminopropyl (meth)acrylamide. These can be used alone or in combination of two or more.

(Physical properties)

The acrylic copolymer (A) containing the components (a1) to (a3) in the monomer composition preferably has a weight average molecular weight (measured by GPC, converted to standard polyethylene) of 1 million or more and 2.5 million or less. A better weight average molecular weight is in the range of 1.2 million to 2.2 million. If the weight average molecular weight is less than 1 million, when the adhesive layer is used as an adhesive composition and used as a polarizing plate, the durability of the adhesive layer tends to be insufficient. On the other hand, if the weight average molecular weight exceeds 2.5 million, the viscosity of the acrylic copolymer is very high, and the coatability is also deteriorated, which is not good.

The acrylic copolymer (A) satisfying the above conditions can usually be produced by solution polymerization, bulk polymerization, emulsion polymerization, suspension polymerization, or the like. Tejia produces acrylic copolymer (A) by solution polymerization obtained as a solution. That is, by obtaining the acrylic copolymer (A) as a solution, it can be used directly to manufacture the adhesive composition of this embodiment. Examples of the solvent used for this solution polymerization include organic solvents such as ethyl acetate, toluene, n-hexane, acetone, and methyl ethyl ketone.

(Polymerization initiator)

As the polymerization initiator used when copolymerizing the monomers containing the components (a1) to (a3), the conventionally known ones can be used. Examples include peroxides such as benzoyl peroxide and lauryl peroxide; azobis compounds such as azobisisobutyronitrile and azobisvaleronitrile; high-molecular azo polymerization initiators; etc.; these can be used alone Or use in combination. In addition, in order to adjust the molecular weight of the acrylic copolymer (A) synthesized, a conventionally known chain transfer agent may also be used as appropriate.

[Hardener (B)]

系化合物及三聚氰胺系化合物。此時此等之使用量係相對於上述丙烯酸系共聚合體(A)100質量份，較佳為0.1質量份以上且15質量份以下之範圍內，更佳係0.1~10質量份之範圍內。本發明所使用之構成黏著劑組成物的硬化劑(B)之使用量，係配合屬於上述丙烯酸系共聚合體(A)之原料之具反應性官能基之乙烯性不飽和單體(a3)的調配量或種類而適當決定即可。使用量若少於上述範圍，則黏著劑層之凝集力降低，在本發明課題之嚴苛耐久性條件下，有發生黏著劑層之發泡之虞；另一方面，若超過上述範圍，則黏著劑組成物之凝集力變得過多，有成為所貼黏之偏光板之剝離原因之虞，故不佳。 The hardener (B) constituting the adhesive composition used in the present invention contains an isocyanate-based compound, and the amount of use thereof is relative to 100 parts by mass of the acrylic copolymer (A), preferably 0.01 parts by mass or more. 10 parts by mass or less, more preferably 0.01 to 4.00 parts by mass. In the present invention, the conventionally known hardeners listed below may be used in combination with the above as necessary. Examples include metal chimeras, epoxy compounds, acridine

Compounds and melamine compounds. In this case, the amount used is preferably within a range of 0.1 parts by mass or more and 15 parts by mass or less, and more preferably within a range of 0.1 to 10 parts by mass, relative to 100 parts by mass of the acrylic copolymer (A). The amount of the hardener (B) constituting the adhesive composition used in the present invention is blended with the ethylenically unsaturated monomer (a3) having a reactive functional group which is the raw material of the acrylic copolymer (A) mentioned above The amount or type of blending may be appropriately determined. If the amount of use is less than the above range, the cohesive force of the adhesive layer decreases, and under the severe durability conditions of the subject of the present invention, there is a risk of foaming of the adhesive layer; on the other hand, if it exceeds the above range, then The cohesive force of the adhesive composition becomes excessive, which may cause peeling of the polarizing plate to be adhered, which is not good.

The isocyanate-based compound is preferably a polyisocyanate compound having two or more isocyanate groups in one molecule, and examples thereof include hexamethylene diisocyanate, dimethyl diisocyanate, toluene diisocyanate, and isophor Adducts such as ketone diisocyanate and trimethylolpropane, etc., trimeric isocyanate compounds, biuret type compounds, etc. Preferably, the compounds of toluene diisocyanate and dimethyl diisocyanate can be used alone or in combination.

系化合物、三聚氰胺系化合物。 Specific examples of the hardener that can be used in combination with the aforementioned isocyanate-based compound as necessary may include, for example, the following. Examples of the metal chimera compound include aluminum chimera, zirconium chimera, and titanium chimera. Examples of the epoxy compound include bisphenol type compounds, aliphatic glycidyl ether compounds, and biphenyl type compounds, or epoxy resins having two or more epoxy groups in the molecule. Also, other cross-linking agents such as acridine can also be used

Compounds, melamine compounds.

[Antistatic agent (C)]

The adhesive layer constituting the adhesive sheet of the present invention is composed of an adhesive composition containing the antistatic agent (C) as a constituent together with the acrylic copolymer (A) and the hardener (B). Since the adhesive composition contains an antistatic agent (C), the formed adhesive layer shows durability under severe conditions, and also shows that its surface resistance value is less than 5.0×10 ⁹ Ω/□, and further 4.0× 10 ⁹ Ω/□ Superior antistatic performance that cannot be achieved by conventional technology.

The antistatic agent (C) is not particularly limited, and conventionally known ones can be used. Among them, a compound containing either fluorine or silicon (which contains no alkali metal salt) is preferable in its structure. The compound represented by the ^- as the alkali metal salts such as KN (FSO _{2) 2,} etc. by the _{^{M + [(FSO 2) 2}} N] can be exemplified. Specific examples include ethylmethylimidazolium bis(trifluoromethanesulfonyl)amideimide, ethylmethylimidazolium bis(fluorosulfonyl)amideimide, 4-methyl-1-octylpyridine Onium bis(trifluoromethanesulfonyl)amide imide, 4-methyl-1-octylpyridinium bis(fluorosulfonyl)amide imide, tributylmethylammonium bis(trifluoromethanesulfonyl)amide Imine, tributylbenzylammonium bis(fluorosulfonyl)amide imine, lauryltrimethylammonium bis(fluorosulfonyl)amide imine, 1-octyl-4-methylpyridinium hexafluoro Phosphate, etc.

The use amount of the above-mentioned antistatic agent (C) is relative to 100 parts by mass of the acrylic copolymer (A) of a specific composition prescribed by the present invention, and is preferably added in a range of more than 0.01 parts by mass and less than 10 parts by mass. The use amount of the better antistatic agent (C) is 0.1 to 8 parts by mass. By setting the amount of the antistatic agent (C) to the above range, an adhesive sheet having an adhesive layer that balances superior antistatic performance and durability under severe conditions can be made. If it is less than the above range, the superior antistatic performance cannot be imparted to the target; if it is more than the above range, the cohesive force of the formed adhesive layer is reduced, which may affect the durability, which is not good.

[Other ingredients]

The adhesive composition constituting the adhesive sheet of the present invention may be in a form further containing a silane coupling agent (D). As the silane coupling agent (D) used, any of the silane coupling agents known in the adhesive field can be used. The amount of the silane coupling agent (D) used is within a range of 0.01 to 5 parts by mass relative to 100 parts by mass of the acrylic copolymer (A).

The adhesive composition constituting the adhesive sheet of the present invention can also contain various required properties in accordance with the purpose of adjusting the adhesive force and the like, and further contain various additives within the range not detracting from the effects of the present invention. For example, it may contain adhesiveness-imparting resins, antioxidants, ultraviolet absorbers, fillers such as terpene-based, terpene-phenol-based, lavender-indene-based, styrene-based, rosin-based, xylene-based, phenolic or petroleum-based. , Pigments, etc.

[Surface resistance value of the adhesive layer of the adhesive sheet]

The adhesive sheet of the present invention is characterized in that the surface resistance value of the adhesive layer formed by the adhesive composition constituted above is less than 5.0×10 ⁹ Ω/□ and further 4.0×10 ⁹ Ω/□ or less The unprecedented low value. It is preferably 2.0×10 ⁹ Ω/□ or less. When forming an adhesive layer by a conventional adhesive composition, in order to make the surface resistance value less than 5.0×10 ⁹ Ω/□, more antistatic agents must be used. On the other hand, if the antistatic agent increases, the cohesive force decreases, so there is a problem that the durability deteriorates under severe environmental conditions at high temperature (105°C or 115°C) or high temperature and high humidity. In contrast, the adhesive layer constituting the adhesive sheet of the present invention is composed of monomers of the acrylic copolymer (A) by using the component (a2) specified in the general formula (1) in a specific ratio as the monomer. Under the above severe durability conditions, peeling or foaming does not occur, and the influence of static electricity on the polarizing film can be reduced, and the surface resistance value can be obtained to be less than 5.0×10 ⁹ Ω/□, and further 4.0×10 ⁹ Ω /□ The following amazing effect.

The surface resistance value specified in the present invention is a value measured using a high resistance meter (trade name: Hiresta-UX MCP-HT450) manufactured by Mitsubishi Chemical Analytech. Specifically, an evaluation sample was prepared by forming an adhesive layer with a thickness of 20 μm from the release film, cut to the measurement size, and then the release film was peeled off at a constant temperature of 23±2°C and a humidity of 50±5%RH. For the wet room, use the value measured by the high resistance meter.

[Polarizer]

The adhesive sheet of the present invention having an adhesive layer formed by the above adhesive composition is used for attaching a polarizing plate. The form of the adhesive sheet of the present invention is not particularly limited as long as it has a release film or the like and an adhesive layer. Generally, it is a state before forming an adhesive layer on a release film or the like and sticking to a polarizing plate. One of the remarkable effects of the present invention can be obtained under the following conditions: the state where one of the above adhesive layers is adhered to the polarizing plate and the other adhesive area is laminated with a release film, etc. It is peeled off and bonded to the outer surface of the glass substrate, for example. That is, since the adhesive sheet of the present invention has excellent antistatic performance, under the above-mentioned conditions, the amount of static electricity generated when the release film is peeled off from the adhesive layer can be suppressed. As a result, the adverse effects on the liquid crystal display device due to the occurrence of static electricity can be reduced.

Furthermore, in addition to the above effects, the adhesive sheet of the present invention can also achieve significant effects that cannot be achieved by conventional technologies that are superior in durability under more severe environmental conditions. Specifically, even under the severe environment of high temperature (105°C or 115°C) or high temperature and high humidity, the polarizing plate is not peeled off from the glass substrate or the like, or foaming occurs in the adhesive layer, which can be achieved Durability under severe conditions. Furthermore, it is possible to suppress the occurrence of the blanking phenomenon of the image display screen, which is easy to occur when the liquid crystal display device is used in a severe environment. The polarizing plate that can use the adhesive sheet of the present invention is not particularly limited, and can be used for sticking conventionally known polarizing plates. Specific examples include general polarizers (when untreated TAC films are used), polarizers coated with disc-type liquid crystals, or uncoated polarizers, or stretched films such as stretched triethyl acetyl cellulose Films, polarized plates with stretched polycycloolefin-based films or stretched cellulose acetate propionate films as substrates, etc.

The adhesive sheet of the present invention in the form of an adhesive layer formed on a release film or the like can be manufactured by the following procedure. Using a commonly used coating device, such as a roll coating device, etc., first, a polyethylene terephthalate film (PET film) plasma release film coated with a release agent such as polysiloxane resin on the surface, The adhesive composition specified in the present invention is applied and dried to form an adhesive layer, whereby it can be easily manufactured. Then, the polarizing plate can be immediately attached to the adhesive layer on the side without the release film, or after the release film is stored on both sides of the adhesive layer, the release film can be peeled off and bonded as needed. Polarizer. Furthermore, in any of the above cases, depending on the constituent materials of the adhesive composition, photo-hardening may be performed by heating, crosslinking, ultraviolet rays, or the like as necessary to form an adhesive layer.

The adhesive layer constituting the adhesive sheet of the present invention can be formed according to the above-mentioned enumeration method using the adhesive composition specified in the present invention. The coating amount of these adhesive compositions is preferably such that the thickness of the adhesive layer after drying becomes about 10 to 50 μm. More preferably, the thickness of the adhesive layer after drying becomes about 10 to 25 μm. By setting the thickness of the adhesive layer within the above range, it can be an adhesive sheet with a better balance between durability and antistatic properties. Moreover, as described above, by using the commonly used means, using the above adhesive sheet of the present invention, for example, attaching a polarizing plate to a glass substrate of a liquid crystal display device, the remarkable effect of the present invention can be obtained.

[Example]

Next, the present invention will be described more specifically by listing production examples, examples, and comparative examples. In addition, "parts" and "%" in the text are quality standards.

[Production Example 1] (Manufacture of acrylic copolymer)

In a reaction device equipped with a stirrer, a thermometer, a reflux cooler and a nitrogen introduction tube, after nitrogen gas is enclosed, 140 parts of ethyl acetate belonging to the reaction solvent are filled with 80 parts of butyl acrylate (BA) as the component (a1) as (a2) 20 parts of phenoxy diethylene glycol acrylate (produced by Kyoei Co., Ltd., trade name "LIGHT ACRYLATE P2HA"), 2 parts of (a3) hydroxyethyl acrylate (HEA), and 0.05 parts of azobisisobutyronitrile as the initiator. While stirring it, it was reacted at 55°C for 7 hours in a nitrogen stream. After the reaction was completed, it was diluted with ethyl acetate to obtain an acrylic copolymer composition solution A1 having a solid content of 15.0% and a weight average molecular weight of 2 million.

[Production Examples 2-18]

Except that the components (a1) to (a3) used in Production Example 1 were used according to the types and amounts described in Table 1 (Table 1-1 and Table 1-2), the rest was carried out in the same manner as in Production Example 1 to obtain The acrylic copolymer composition solutions A2 to A11 used, and the acrylic copolymer composition solutions B1 to B7 used in the comparative example.

The abbreviations in Table 1 are as follows.

‧BA: Butyl acrylate

‧MA: methyl acrylate

‧P2HA: phenoxy diethylene glycol acrylate: manufactured by Kyoei Co., Ltd. under the trade name "LIGHT ACRYLATE P2HA"

‧P-300A: Phenoxy triethylene glycol acrylate: manufactured by Kyoei Co., Ltd. under the trade name "LIGHT ACRYLATE P-300A"

‧FA-314A: Nonylphenoxy polyethylene glycol acrylate: Hitachi Chemical Co., Ltd., trade name "FA-314A"

‧FA-318A: Nonylphenoxy polyethylene glycol acrylate: Hitachi Chemical Co., Ltd., trade name "FA-318A"

‧PHEA: Phenoxyethyl acrylate: manufactured by Kyoei Co., Ltd. under the trade name "LIGHT ACRYLATE PO-A"

‧EC-A: Epoxy triethylene glycol acrylate: manufactured by Kyoei Co., Ltd. under the trade name "LIGHT ACRYLATE EC-A"

‧FA-400M: Methoxy polyethylene glycol #400 methacrylate: Hitachi Chemical Co., Ltd., trade name "FA-400M(100)"

‧HEA: Hydroxyethyl acrylate

‧4HBA: 4-hydroxybutyl acrylate

‧AAC: Acrylic

‧Β-CEA: β-carboxyethyl acrylate

‧GA: glycidyl acrylate

‧GMA: glycidyl methacrylate

‧4HBAGE: 4-hydroxybutyl acrylate epoxypropyl ether

‧AM: Acrylate

‧MAM: amide methacrylate

‧DMAPAA: Dimethylaminopropyl Acrylate

[Example 1] (Manufacture of adhesive composition)

With respect to 100 parts of the solid content of the acrylic copolymer composition solution A1 obtained above, CORONATE L (trade name, trimethylolpropane adduct of TDI manufactured by Nippon Polyurethane Co., Ltd.) as an isocyanate-based hardener was added, and the solid concentration was 75 %) 0.50 parts by solid content, 5.0 parts of ethylmethylimidazolium bis(trifluoromethanesulfonyl) amide imide as antistatic agent, X-41-1810 as a silane coupling agent (trade name, Shin-Etsu) 0.8 parts by a chemical company) and thoroughly mixed to obtain an adhesive composition 1.

(Manufacture of Adhesive Sheet 1)

After the adhesive composition 1 obtained above was coated on a PET film belonging to a silicone-coated release film, the solvent was removed by drying at 90°C to form an adhesive layer with a dry thickness of 20 μm. After bonding the surface on which the adhesive layer is formed to one side of the polarizing film, it is aged for 7 days in an environment of 23°C and 50% RH, thereby obtaining an adhesive sheet 1 having a release film and an adhesive layer Optical components as constituent elements.

[Examples 2 to 20, Comparative Examples 1 to 9]

Except for replacing the acrylic copolymer composition solution A1 used in Example 1, according to the types and amounts described in Table 2 (Table 2-1, Table 2-2, Table 2-3), the acrylic copolymer composition used in the Examples was used Except for the solution A1 to A11 and the acrylic copolymer composition solutions B1 to B7 used in the comparative example, the rest was carried out in the same manner as in Example 1 to obtain the adhesive composition 2 to 20 used in the example and the adhesive composition used in the comparative example Things 21~29. Then, except for using the adhesive compositions 2 to 29, the same procedure as in Example 1 was carried out to obtain the adhesive sheets 2 to 20 of Examples 2 to 20 and the adhesive sheets 21 to 29 of Comparative Examples 1 to 19, respectively. .

<Evaluation method> 1. Preparation of polarizing plates for evaluation samples (adhered body: polarizing film)

Using each of the adhesive compositions prepared in the examples and the comparative examples, an adhesive layer was formed on the polarizing plate according to the following method, and a polarizing plate with an adhesive layer belonging to a sample for evaluation was manufactured. That is, after applying the adhesive composition 1 to 29 on the PET film (release substrate) which is a release film coated with silicone resin, the solvent is removed by drying at 90°C to form a thick 20μm adhesive layer. After bonding the polarizing film with a thickness of 110 μm on the surface on which the adhesive layer was formed, it was aged for 7 days in an environment of 23° C. and 50% RH to prepare samples for evaluation. The size of the sample for evaluation is set to 80 mm×150 mm, and the polarizing film uses a TAC polarizing plate. Then, using the samples for evaluation of the laminated adhesive layer and the release film and the polarizing film prepared as described above, each test described below was performed, and evaluation was performed according to each evaluation criterion. Then, the results are shown in Table 3. Table 3-1 and Table 3-2 show the results of the samples for evaluation in Examples, and Table 3-3 show the results of the samples for Evaluation in Comparative Examples.

2. Durability (1) Durability at 105℃

Using each sample for evaluation, the release film was peeled off to expose the adhesive layer, attached to the glass, and then left in an environment of 105°C (DRY) for 500 hours. After leaving, visual observation (10 times magnifying glass can be used. The same applies to the following) and confirmation of foaming and peeling occurred in the adhesive layer, and evaluation was performed according to the following criteria. Table 3 shows the evaluation results.

(2) Durability at 115℃

Using each sample for evaluation, the release film was peeled off to expose the adhesive layer, and after being attached to the glass, it was left at 115°C (DRY) for 500 hours. After leaving, visual observation and confirmation were made for foaming and peeling that occurred in the adhesive layer, and evaluation was performed according to the following criteria, and the evaluation results are shown in Table 3.

(3) Durability at 65℃ and 95%RH

After attaching the evaluation sample to the glass, and leaving it in a high-temperature and humid environment at 65°C and 95% RH for 500 hours, visually observe and confirm foaming and peeling, and evaluate according to the following criteria, as shown in Table 3. Evaluation results.

(Evaluation criteria) 1) About foaming

○: No foaming was confirmed on the polarizing plate.

△: Although slight foaming was confirmed on the polarizing plate, it was practically problem-free.

×: Foaming was confirmed on the polarizing plate.

2) About stripping

○: No peeling was confirmed on the polarizing plate.

△: Although slight peeling was confirmed on the polarizing plate, it was practically problem-free.

×: Significant peeling was confirmed on the polarizing plate.

3. Tackiness

The adhesive layer of the sample for evaluation was wiped with a finger 10 times, and the number of times until the polarizing film (TAC polarizing plate) peeled off was used to evaluate the adhesiveness. In addition, the number of occurrences of peeling between 1 and 9 times is described, and the number of times where no peeling occurs even after 10 wipes is described as ">10".

4. Surface resistance

The separator of the sample for evaluation was exposed to expose the adhesive layer, and a high resistance meter (trade name: Hiresta-UX) manufactured by Mitsubishi Chemical Analytech was used under room temperature conditions of 23±2°C and 50±5%RH. MCP-HT450) and measuring electrode, measuring the surface resistance value (Ω/□) of the adhesive layer.

5. Leave blank

Use 2 samples after attaching the evaluation sample to the glass and place it under a high-temperature and humid environment at 65°C 95%RH for 500 hours (it can also be the latter of the durability test at 65°C 95%RH). The upper and lower sides of the liquid crystal panel are bonded as cross polarizers. Turn on the backlight of the LCD screen, visually observe the state of the blank, and evaluate according to the following criteria.

[Evaluation criteria]

○: No blanking was observed on the polarizing plate.

△: Slight whitening was observed on the polarizing plate.

×: White space was observed on the polarizing plate.

6. Overall evaluation

The overall evaluation is performed according to the following criteria.

[Evaluation criteria]

A: The evaluation of durability is ○ under all environmental conditions, the evaluation of adhesion is ≧8, the surface resistance of the adhesive layer is 4.0×10 ⁹ Ω/□ or less, and the evaluation of whiteness is ○ Happening.

B: Durability is evaluated in one of the environmental conditions. Slight foaming and/or peeling is confirmed on the polarizing plate. The adhesion evaluation is ≧8, and the surface resistance of the adhesive layer is 4.0×10 ⁹ Ω/□ or less, and the blank evaluation is ○.

C: The evaluation of durability is confirmed by one of the environmental conditions. Slight foaming and/or peeling is confirmed on the polarizing plate. The evaluation of adhesion is ≧8, and the surface resistance value of the adhesive layer exceeds 4.0×10 ⁹ Ω/□ and less than 5.0×10 ⁹ Ω/□, and the blank evaluation is ○.

D: The evaluation of durability is that foaming and/or peeling is confirmed on the polarizing plate in one of the environmental conditions, the evaluation of adhesion is <8 and ≧6, and the surface resistance value of the adhesive layer is less than 5.0 ×10 ⁹ Ω/□, and the evaluation of the blank is △ or ×.

E: Durability is evaluated in one of the environmental conditions where foaming and/or peeling is confirmed on the polarizing plate, the adhesion evaluation is <6, and the surface resistance value of the adhesive layer is 5.0×10 ⁹ Ω /□ Above.

As shown in Table 3-1 and Table 3-2, the adhesive layer formed by the adhesive composition constituting the adhesive sheet of the embodiment is obtained by using the unique (a2) component as the specified amount of the present invention as The monomer composition of the acrylic copolymer (A), as explained by comparison with Comparative Examples 1 to 6, 8, and 9, it was confirmed that superior durability under severe conditions that cannot be achieved by conventional technology can be achieved, In addition, the surface resistance value is less than 5.0×10 ⁹ Ω/□, and almost all the examples are less than 4.0×10 ⁹ Ω/□, and further less than 3.0×10 ⁹ Ω/□. In addition, the adhesive layer constituting the adhesive sheet of the embodiment of the present invention has high practical value because it achieves sufficient adhesion of important characteristics in the polarizing plate and suppresses the occurrence of blanking.

Claims (5)

An adhesive sheet comprising a release film or a release paper and an adhesive layer, which is an adhesive sheet for attaching a polarizing plate, characterized in that the adhesive layer contains at least an acrylic copolymer (A ), an adhesive composition composed of a hardener (B) and an antistatic agent (C); the above antistatic agent (C) is a compound containing either fluorine or silicon in its structure (wherein M is an alkali metal of ^{_{+ [(FSO 2) 2 N}} ] - except in the case of the compound represented by), with respect to the acrylic of copolymer (a) 100 parts by mass, 3.5 parts by mass or more and less than 10 parts by mass The amount of the range is added; the above-mentioned acrylic copolymer (A)-based monomer composition contains at least one type of ethylenically unsaturated monomer (a1) containing no more than 50% by mass and less than 85% by mass of non-reactive functional groups, And contains at least one type of monomer (a2) represented by the following general formula (1) greater than 15% by mass and 50% by mass or less; and, relative to the above monomer (a1) and the above monomer (a2) A total of 100 parts by mass, which is obtained by copolymerizing at least one type of monomer containing an ethylenically unsaturated monomer (a3) having a reactive functional group according to 0.01 parts by mass or more and 5 parts by mass or less; The surface resistance value is below 4.0×10 ⁹ Ω/□;

(In general formula (1), R ¹ represents a hydrogen atom or a methyl group, R ² represents any one of a hydrogen atom, an alkyl group, an aralkyl group, or an aryl group, and n represents any integer of 2 to 9). The adhesive sheet according to claim 1, wherein the reactive functional group of the ethylenically unsaturated monomer (a3) having a reactive functional group is selected from the group consisting of a hydroxyl group, a carboxyl group, an epoxypropyl group, and a nitrogen-containing group At least any one of the groups. The adhesive sheet according to claim 1 or 2, wherein the hardener (B) contains an isocyanate-based compound, and the usage amount thereof is 0.01 parts by mass or more with respect to 100 parts by mass of the acrylic copolymer (A). Within 10 parts by mass or less. The adhesive sheet according to claim 1 or 2, wherein the adhesive composition further contains a silane coupling agent (D). The adhesive sheet according to claim 1 or 2, wherein the adhesive composition further contains a silane coupling agent (D); the hardener (B) contains an isocyanate compound, and the amount of use is relative to the acrylic acid 100 parts by mass of the system copolymer (A) is within a range of 0.01 parts by mass or more and 10 parts by mass or less.