KR20200001485A - Adhesive sheet - Google Patents

Abstract

The present invention is to provide an adhesive sheet for adhering a polarizing plate, which includes an adhesive layer which has a high antistatic function, is capable of implementing durability under strict conditions, and is configured to inhibit a color spot and a white spot from being generated on a display screen. The adhesive layer comprises an adhesive composition which includes: an acryl-based copolymer (A); a curing agent; and an antistatic agent (C). (C) is a compound including fluorine or silicon except when M includes a compound which is an alkali metal and is represented by M^+[(FSO_2)_2_N]^-. In addition, (A) is added in an amount of 100 parts, 3.5 parts or more, and less than 10 parts. (A) includes more than 15% and 50% or less of a monomer represented by a general formula (1) and 0.01-5 parts of a monomer having a reactive functional group in a monomer composition, and a surface resistance value of the adhesive layer is 4.0×10^9Ω/□ or less.

Description

Adhesive sheet {ADHESIVE SHEET}

This invention relates to the adhesive sheet which has a release film or a release paper, and an adhesive layer used in order to adhere | attach the polarizing plate used for optical components, such as a liquid crystal cell of a liquid crystal display device.

In recent years, the liquid crystal display device has been widely used as a display device such as a vehicle mount, an outdoor instrument, a personal computer, or a display device such as a television due to the reduction in weight and thickness, and the demand tends to increase gradually. Is in. In connection with this, the use environment of a liquid crystal display device is also adding various, and it is necessary to respond to the severe conditions regardless of indoors and outdoors. Here, a liquid crystal display device is a polarizing plate or a polarizing plate through the adhesive layer formed with the adhesive composition for optics on the outer surface of the glass substrate of a liquid crystal cell (it is comprised by sandwiching the liquid crystal component orientated in the predetermined direction with two glass substrates). And a laminate with a retardation plate (hereinafter, these are collectively referred to as a "polarizing plate").

The above-mentioned polarizing plate generally has a three-layer structure in which both surfaces of a polarizer made of a polyvinyl alcohol-based material are sandwiched and laminated with a triacetyl cellulose-based protective film, but the dimensional stability is insufficient due to the properties of these materials. Moreover, since a polarizing plate is shape | molded by extending | stretching, expansion and contraction by heat and humidity are easy to occur. For this reason, in a liquid crystal display device, if the adhesive layer used for lamination | stacking cannot absorb the internal stress which arises by the expansion and contraction of a polarizing plate, the distribution of the residual stress acting on a polarizing plate will become nonuniform. In particular, when stress is concentrated in the peripheral portion, consequently, the peripheral edge of the display portion of the liquid crystal display device becomes brighter or darker than the center, resulting in color speckles and white spots on the liquid crystal display surface. (白 拔) phenomenon occurs.

Moreover, about the adhesive layer which comprises a polarizing plate, in addition to said technical subject, it is necessary to peel a release film and a release paper which are stuck to an adhesive surface at the time of sticking, but static electricity generate | occur | produces when peeling, and it passes through an adhesion layer There is a problem that it affects the functional material to be laminated. Specifically, for example, if static electricity is generated when the release film is peeled from the pressure-sensitive adhesive layer provided on the polarizing plate, the static electricity affects the liquid crystal layer inside the liquid crystal cell, resulting in a bad state. In the liquid crystal display of the touch sensor unit, adverse effects such as a malfunction of the capacitive sensor are caused. As a means of suppressing generation of static electricity when peeling off a release film, there exists a method of providing antistatic property to an adhesive layer. On the other hand, as follows, in recent years, the level required for the antistatic performance has become significantly higher than before.

In order to raise antistatic performance, it is necessary to add an antistatic agent. However, when there is too much addition amount, the cohesion force of an adhesive falls and there exists a tendency for peeling and foaming of an adhesive layer to generate especially in strict durability conditions. Therefore, the formed pressure-sensitive adhesive layer has satisfactory durability (hereinafter, referred to as "durability under strict conditions") under strict durability conditions, and also causes color spots and white spots on the display surface of the display device. Can be suppressed, and furthermore, it is very difficult and difficult to achieve excellent antistatic performance when the above release film is peeled off.

In particular, since liquid crystal display devices have been widely used in a wide range of fields in recent years, for example, in vehicle-mounted applications such as automobile navigation, the use environment also varies, such as the inside of a vehicle becoming a sealed space, which has a very high temperature. In addition, durability under the stricter conditions than before has been demanded. For this reason, in the conventional adhesive used for liquid crystal display devices, such as for TVs mounted at room temperature, there exists a subject that durability is not enough.

Regarding the adhesive used for the liquid crystal display device having these problems, various proposals have been made so far. For example, in patent document 1, the copolymer obtained from the monomer mixture containing the (meth) acrylic acid ester, the unsaturated monomer (acrylic acid 2-phenoxyethyl) which has an aromatic ring, and the unsaturated monomer which has a polar functional group, and at room temperature The adhesive composition which consists of a solid ionic compound (antistatic agent) and a crosslinking agent is proposed. Moreover, in patent document 2, the adhesive containing the (meth) acrylic-type polymer (A) and alkali metal salt (B) containing an alkyl (meth) acrylate and an alkyl (meth) acrylate containing an aromatic ring as a monomer unit. There is a proposal for a composition. Moreover, in patent document 3, the (meth) acrylic acid ester copolymer containing an alicyclic structure containing monomer (a1), an aromatic ring containing monomer (a2), and an oxyalkylene group containing monomer (a3) as a monomer unit which comprises a polymer. The adhesive composition containing (A) and a crosslinking agent (B) is proposed.

In addition, such as KN (FSO _{2) 2} as an antistatic _{^{agent, M + [(FSO 2)}} 2 N] - there is a proposal for a pressure-sensitive adhesive composition used as an antistatic agent a specific alkali metal salt represented by, in the embodiment It is described that the surface resistance value of the adhesive sheet using the adhesive composition is 4.0x10 <^9> ohms / square or less.

Japanese Laid-Open Patent Publication No. 2010-066755 Japanese Laid-Open Patent Publication No. 2016-020287 Japanese Patent Laid-Open No. 2017-134134 Korean Laid-Open Patent Publication No. 10-2010-0018414

However, according to the studies by the present inventors, the pressure-sensitive adhesive composition proposed in Patent Literature 1 has a balance between achieving the durability under high stringent conditions and providing antistatic performance to a high level. It wasn't too early to realize that. In addition, although the adhesive composition proposed by patent document 2 and the adhesive composition proposed by patent document 3 are both obtained, the adhesive layer which has the outstanding antistatic performance is obtained, but it placed under the strict use environment in recent years. It did not satisfy "durability under strict conditions" demanded in cases. Although the surface resistance value of the adhesive sheet formed from the adhesive composition described in patent document 4 is 4.0 * 10 <^{9> (} ohm) / square or less, the effect of the durability is left to stand in an oven of 60 degreeC and 90% of a relative humidity for 300 hours. The peeling phenomenon, the generation of bubbles, and the observation of light leakage are kept, and it is not possible to satisfy the more stringent durability which is a problem in the present invention.

Accordingly, an object of the present invention is to provide excellent antistatic performance, which is not yet realized, which is useful for the formation of an adhesive layer constituting a polarizing plate which is widely used in a wide range of fields in recent years, and also to the durability under strict conditions and to a display screen. It is providing the adhesive sheet which can suppress generation | occurrence | production of a color stain and a white spot phenomenon. In particular, it is an object of the present invention to provide an adhesive composition for forming an adhesive layer of the above useful adhesive sheet.

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

[1] An adhesive sheet for polarizing plate adhesion, comprising a release film or a release paper and an adhesive layer,

The said adhesive layer consists of an adhesive composition which contains an acryl-type copolymer (A), a hardening | curing agent (B), and an antistatic agent (C) at least,

The antistatic agent (C) includes a compound containing any one of fluorine or silicon in the structure, except that the compound represented by M ⁺ [(FSO ₂ ) ₂ N] ^- , where M is an alkali metal. In addition, it is added in the quantity of the range of 3.5 mass parts or more and less than 10 mass parts with respect to 100 mass parts of said acrylic copolymers (A),

The said acryl-type copolymer (A) contains 50 mass% or more and less than 85 mass% of at least 1 sort (s) of ethylenically unsaturated monomer (a1) in which a monomer composition does not have a reactive functional group, and is following General formula (1) It is more than 15 mass%, and contains 50 mass% or less of at least 1 sort (s) of the monomer (a2) represented by

A monomer containing at least one of ethylenically unsaturated monomers (a3) having a reactive functional group at 0.01 parts by mass or more and 5 parts by mass or less based on 100 parts by mass of the total amount of the monomer (a1) and the monomer (a2). Made by copolymerization,

The surface resistance of the said adhesive layer is 4.0 * 10 <^{9> (} ohm) / square or less, The adhesive sheet characterized by the above-mentioned.

(In general formula (1), R <^1> represents a hydrogen atom or a methyl group, R <^2> represents either a hydrogen atom, an alkyl group, an aralkyl group, or an aryl group, and either of n = 2-9. Is an integer.)

The following are mentioned as a preferable aspect of this invention.

[2] The pressure sensitive adhesive sheet according to [1], wherein the reactive functional group of the ethylenically unsaturated monomer (a3) having the reactive functional group is at least one selected from the group consisting of a hydroxyl group, a carboxyl group, a glycidyl group and a nitrogen-containing group.

[3] The curing agent (B) contains an isocyanate compound, and the amount of the curing agent (B) is in the range of 0.01 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the acrylic copolymer (A). 1] or the adhesive sheet as described in [2].

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

ADVANTAGE OF THE INVENTION According to this invention, it is an adhesive sheet for polarizing plate sticking which consists of a release film or a release paper (henceforth a "release film etc."), and an adhesive layer, and has the outstanding antistatic performance which still has not yet realized, and also strict conditions. When the durability is shown and it is used for an image display part, the adhesive sheet which forms the adhesive layer which can suppress generation | occurrence | production of a color stain and a white spot phenomenon is provided. Moreover, according to this invention, the formation of the adhesive layer which can implement | achieve the outstanding antistatic performance which is not yet realized, and durability under severe conditions, which is useful for forming the adhesive layer which has the said outstanding performance can be achieved. Pressure-sensitive adhesive composition is provided.

Next, the present invention will be described in more detail with reference to preferred embodiments for carrying out the invention. In addition, the term "(meth) acryl" in a claim and specification of this invention means both of "acryl" and "methacryl", and the term "(meth) acrylate" , "Acrylate" and "methacrylate" mean both.

The adhesive sheet of this invention is an adhesive sheet used in order to stick a polarizing plate to optical components, such as a liquid crystal cell of a liquid crystal display device, and the adhesive layer which comprises an adhesive sheet is at least an acrylic copolymer (A) and a hardening agent ( B) and an antistatic agent (C) are contained as a structural component, and also it is formed by the adhesive composition which contains a silane coupling agent (D) as needed. And the adhesive sheet of this invention contains the monomer structure of the acryl-type copolymer (A) contained in the adhesive composition which forms an adhesive layer in the specific range which was specific monomer (a2) prescribed | regulated by the said General formula (1). The antistatic performance of the pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition is less than 5.0 × 10 ⁹ Ω / □ and still less than 4.0 × 10 ⁹ Ω / □. (Hereinafter referred to as &quot; excellent antistatic performance &quot;) and excellent performance not achieved by the prior art, which exhibits durability under strict conditions. Hereinafter, these components which comprise this invention are demonstrated, respectively.

Acrylic Copolymer (A)

As for an acryl-type copolymer (A), at least 1 sort (s) of the ethylenically unsaturated monomer (a1) in which a monomer composition does not have a reactive functional group exists in 50 mass% or more and less than 85 mass%, and is represented by following General formula (1) At least 1 type of monomer (a2) shown is more than 15 mass%, and is a copolymer of the structure which exists in the range of 50 mass% or less. And with respect to 100 mass parts of sum total of a monomer (a1) and a monomer (a2), at least 1 type of ethylenically unsaturated monomer (a3) which has a reactive functional group in the quantity within the range of 0.01 mass part or more and 5 mass parts or less It is an acryl-type copolymer formed by copolymerizing with the monomer composition to contain.

(In general formula (1), R <^1> represents a hydrogen atom or a methyl group, R <^2> represents either a hydrogen atom, an alkyl group, an aralkyl group, or an aryl group, and either of n = 2-9. Is an integer.)

(Monomer (a1))

The ethylenically unsaturated monomer (a1) which does not have a reactive functional group (henceforth only described as "(a1) component") is a monomer composition of the monomer (a1) and monomer (a2) of an acryl-type copolymer (A), It is used in the ratio of 50 mass% or more and less than 85 mass%. When the ratio of the component (a1) is less than 50% by mass, when the pressure-sensitive adhesive layer is formed, the adhesiveness to the base material and the flexibility of the pressure-sensitive adhesive layer decrease, peeling off and lifting from the base material occur, and sufficient durability is achieved. Not obtained. On the other hand, when the ratio of the component (a1) is 85% by mass or more, the adhesion to the substrate is insufficient, and foaming of the pressure-sensitive adhesive layer occurs under strict durability conditions. In addition, the antistatic performance is also insufficient.

As a (a1) component, the (meth) acrylic acid ester monomer which has C1-C18 is mentioned, for example. Specifically, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, Alkyl (meth) acrylates, such as octyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, and lauryl (meth) acrylate, are mentioned. These can be used individually by 1 type or in combination of 2 or more types.

(Monomer (a2))

The acrylic copolymer (A) describes monomer (a2) (hereinafter also referred to only as "(a2) component") represented by the following general formula (1) in the monomer composition of monomer (a1) and monomer (a2). It contains more than 15 mass% in the ratio which occupies at 50 mass% or less, and is synthesize | combined. By including (a2) component in said monomer composition in said monomer composition, in the adhesive layer formed by using the antistatic agent (C) mentioned later, durability and the outstanding antistatic performance under strict conditions which were not realized by the prior art. It becomes possible to make it compatible. That is, when (a2) component is out of the said range, in the adhesive layer formed, it will become difficult to implement | achieve both excellent antistatic performance and durability under strict conditions.

(In general formula (1), R <^1> represents a hydrogen atom or a methyl group, R <^2> represents either a hydrogen atom, an alkyl group, an aralkyl group, or an aryl group, and either of n = 2-9. Is an integer.)

As a specific (a2) component, phenoxy diethylene glycol acrylate, phenoxy triethylene glycol acrylate, nonyl phenoxy polyethylene glycol acrylate, etc. are mentioned, for example. These can be used individually by 1 type or in combination of 2 or more types.

(Monomer (a3))

The monomer composition which synthesize | combines an acryl-type copolymer (A) is ethylenic which has a reactive functional group with respect to 100 mass parts of sum total of (a1) component and (a2) component in addition to the said (a1) component and (a2) component. It is comprised by adding unsaturated monomer (a3) (Hereinafter, it only describes as "(a3) component") in the quantity of 0.01 mass part or more and 5 mass parts or less. More preferably, they are 0.01 mass part or more and 3 mass parts or less. The film formation resin of the adhesive composition which comprises this invention contains (a3) component which reacts with a hardening agent in the said range, and formation of the adhesive layer which is more durable becomes possible. Although a hydroxyl group, glycidyl group, and an amide group are mentioned as a reactive functional group, It is preferable to use the ethylenically unsaturated monomer which has a hydroxyl group especially. When (a3) component is less than the said range with respect to 100 mass parts of sum total of (a1) component and (a2) component in the monomer composition of an acryl-type copolymer (A), the cohesion force of an adhesive layer will fall, and this invention will Under strict durability conditions, which are the subjects, foaming of the pressure-sensitive adhesive layer occurs, and if it exceeds the above range, the adhesiveness to the base material of the pressure-sensitive adhesive layer may be impaired and peeling may occur.

As (a3) component, hydroxyl group containing (meth) acrylic acid ester monomer, such as hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate, (meth) acrylic acid, (beta) -carboxyethyl ( Glycidyl group containing monomers, such as carboxyl group-containing monomers, such as meth) acrylate, glycidyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate glycidyl ether, (meth) acrylamide, and dimethylaminopropyl Amide system monomers, such as (meth) acrylamide, are mentioned. These can be used individually by 1 type or in combination of 2 or more types.

(Properties)

It is preferable that the weight average molecular weight (GPC measurement, standard polystyrene conversion) of the acrylic copolymer (A) which contains said (a1) component-(a3) component in a monomer composition is 1 million or more and 2.5 million or less. More preferable weight average molecular weights are in the range of 1.2 million to 2.2 million. When a weight average molecular weight is less than 1 million, it is set as an adhesive composition and when used as an adhesive layer of a polarizing plate, there exists a tendency for the durability of an adhesive layer to become inadequate. On the other hand, when the weight average molecular weight exceeds 2.5 million, since the viscosity of an acryl-type copolymer is very high and coating property also worsens, it is not preferable.

The acrylic copolymer (A) which satisfies the above-described conditions can be produced by ordinary solution polymerization, lump polymerization, emulsion polymerization or suspension polymerization. In particular, it is preferable to manufacture by solution polymerization in which an acryl-type copolymer (A) is obtained as a solution. That is, when an acrylic copolymer (A) is obtained as a solution, it can be used for manufacture of the adhesive composition of this embodiment as it is. As a solvent used for this solution polymerization, organic solvents, such as ethyl acetate, toluene, n-hexane, acetone, and methyl ethyl ketone, are mentioned, for example.

(Polymerization initiator)

As a polymerization initiator used when copolymerizing the monomer containing said (a1) component-(a3) component, a conventionally well-known thing can be used. For example, peroxides, such as benzoyl peroxide and lauryl peroxide; Azobis compounds, such as azobis isobutyronitrile and azobis valeronitrile; Polymer azo polymerization initiator, etc. are mentioned, These are independent or in combination It is available. Moreover, in order to adjust the molecular weight of the acryl-type copolymer (A) synthesize | combined, a conventionally well-known chain transfer agent can also be used suitably.

Curing Agent (B)

The hardening | curing agent (B) which comprises the adhesive composition used by this invention contains an isocyanate type compound, and the usage-amount is 0.01 mass part or more and 10 mass parts or less with respect to 100 mass parts of said acrylic copolymers (A). It is more preferable to exist in the range of 0.01-4.00 mass parts in the range of. In the present invention, in combination with the above, a conventionally known curing agent listed below can be used as necessary. For example, a metal chelate compound, an epoxy type compound, an aziridine type compound, and a melamine type compound are mentioned. It is preferable that these usage-amounts in that case exist in the range of 0.1 mass part or more and 15 mass parts or less with respect to 100 mass parts of said acrylic copolymers (A), More preferably, it exists in the range of 0.1-10 mass parts. What is necessary is just to determine the usage-amount of the hardening | curing agent (B) which comprises the adhesive composition used by this invention suitably according to the compounding quantity and kind of the ethylenically unsaturated monomer (a3) which has a reactive functional group which is a raw material of said acryl-type copolymer (A). . If the amount of use is less than the above range, the cohesive force of the pressure-sensitive adhesive layer is lowered, and under the strict durability conditions of the present invention, foaming of the pressure-sensitive adhesive layer may occur, whereas if the amount exceeds the above range, the cohesive force of the pressure-sensitive adhesive composition may occur. It is unpreferable since it may become excessive and may cause peeling of the polarizing plate to stick.

As an isocyanate type compound, the polyisocyanate compound which has 2 or more isocyanate groups in 1 molecule is preferable, For example, the thing with hexamethylene diisocyanate, xylene diisocyanate, tolylene diisocyanate, isophorone diisocyanate, etc., trimethylol propane, etc. A duct body, an isocyanurate compound, a biuret type compound, etc. are mentioned. Preferably, it is a compound of tolylene diisocyanate and xylene diisocyanate, and can be used individually or in combination.

The following are mentioned as a specific thing of the hardening | curing agent which can be used together with said isocyanate type compound and can be used as needed. As a metal chelate compound, aluminum chelate, zirconium chelate, titanium chelate, etc. are mentioned, for example. As an epoxy compound, the epoxy resin which has two or more epoxy groups in a molecule | numerator other than a bisphenol-type compound, an aliphatic glycidyl ether compound, and a biphenyl type compound is mentioned. Moreover, another crosslinking agent can also be used and an aziridine type compound, a melamine type compound, etc. are mentioned.

[Antistatic Agent (C)]

The adhesive layer which comprises the adhesive sheet of this invention consists of an adhesive composition which contains an antistatic agent (C) as a structural component with said acrylic copolymer (A) and hardening | curing agent (B). When the pressure-sensitive adhesive composition contains an antistatic agent (C), the pressure-sensitive adhesive layer formed exhibits durability under strict conditions, and its surface resistance value is less than 5.0 × 10 ⁹ Ω / □, furthermore, 4.0 × 10. ^It shows the outstanding antistatic performance which was not achieved by the prior art of ⁹ ohms / square or less.

It does not specifically limit as antistatic agent (C), A conventionally well-known thing can be used. Especially, it is preferable in the structure that it is a compound containing either fluorine or silicon (however, an alkali metal salt is not included). Examples of the alkali metal _{salt, KN (FSO 2), M} + [(FSO 2) 2 N] ₂ and so on ^- may be mentioned a compound represented by. Specifically, for example, ethyl methyl imidazolium bis (trifluoromethanesulfonyl) imide, ethyl methyl imidazolium bis (fluorosulfonyl) imide, and 4-methyl- 1-octyl pyridinium bis | (Trifluoromethanesulfonyl) imide, 4-methyl-1-octylpyridinium bis (fluorosulfonyl) imide, tributylmethylammonium bis (trifluoromethanesulfonyl) imide, tributylbenzylammonium Bis (fluorosulfonyl) imide, lauryltrimethylammonium bis (fluorosulfonyl) imide, 1-octyl-4-methylpyridinium hexafluorophosphate, and the like.

The usage-amount of said antistatic agent (C) is externally added in the range which is more than 0.01 mass part and less than 10 mass parts with respect to 100 mass parts of acrylic copolymers (A) of the specific structure prescribed | regulated by this invention. desirable. The usage-amount of a more preferable antistatic agent (C) is 0.1-8 mass parts. By setting the amount of the antistatic agent (C) in the above range, it is possible to obtain an adhesive sheet having a pressure-sensitive adhesive layer that has both excellent antistatic performance and durability under strict conditions. If it is less than the above range, the desired antistatic performance cannot be imparted, and if it is more than the above range, the cohesion force of the formed pressure-sensitive adhesive layer is lowered, which may affect durability.

[Other Ingredients]

The adhesive composition which comprises the adhesive sheet of this invention can be made into the form which further contains a silane coupling agent (D). As a silane coupling agent (D) to be used, any well-known silane coupling agent can be used in the field of an adhesive. It is preferable that the usage-amount of a silane coupling agent (D) exists in the range of 0.01-5 mass parts with respect to 100 mass parts of acryl-type copolymers (A).

The adhesive composition which comprises the adhesive sheet of this invention may further contain various additives in the range which does not impair the effect of this invention according to the required performance for the purpose of adjusting adhesive force. For example, it can contain tackifying resins such as terpene, terpenephenol, coumarone indene, styrene, rosin, xylene, phenol or petroleum, antioxidants, ultraviolet absorbers, fillers, pigments and the like. .

[Surface Resistance Value of Adhesive Layer of Adhesive Sheet]

The pressure-sensitive adhesive sheet of the present invention has no surface resistance value of the pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition of the above-described structure, which is less than 5.0 × 10 ⁹ Ω / □, and more than 4.0 × 10 ⁹ Ω / □, which is not conventionally known. It is characterized by a low value. Preferably, it is 2.0 * 10 <^9> ohms / square or less. When the adhesive layer was formed by the conventional adhesive composition, it was necessary to use many antistatic agents in order to make surface resistance value less than 5.0x10 <^{9> (} ohm) / square. On the other hand, when the antistatic agent is increased, the cohesive force is lowered, so that there is a problem that durability is inferior under severe environmental conditions under high temperature (105 ° C or 115 ° C) or high temperature and high humidity. In contrast, the pressure-sensitive adhesive layer constituting the pressure-sensitive adhesive sheet of the present invention uses the (a2) component defined by the general formula (1) as a monomer composition of the acrylic copolymer (A) at a specific ratio, thereby providing the above-mentioned strictness. Even under the durability conditions, peeling and foaming do not occur, and in addition, the influence of static electricity on the polarizing film or the like can be reduced, and the surface resistance value is less than 5.0 × 10 ⁹ Ω / □, moreover, 4.0 × 10 ⁹ Ω / □ I get the surprising effect that I can do it as follows.

The surface resistance value prescribed | regulated by this invention is the value measured using the high resistivity meter (brand name: Hirester UX # MCP-HT450) made by Mitsubishi Chemical Analyzer. Specifically, a pressure-sensitive adhesive layer having a thickness of 20 μm is formed on a release film to prepare an evaluation sample, and after cutting to a size for measurement, the release film is peeled off, and the constant temperature is 23 ± 2 ° C. and a humidity of 50 ± 5% RH. It is the value measured using the high resistivity meter in a humidity chamber.

[Polarizing Plate]

The adhesive sheet of this invention which has the adhesive layer formed of the adhesive composition mentioned above is used for sticking of a polarizing plate. As a form of the adhesive sheet of this invention, what is necessary is just to have a release film etc., and an adhesive layer is not specifically limited. The thing of the state before affixing on the polarizing plate in which the adhesive layer is formed on a release film etc. is common. One of the remarkable effects of the present invention is that the one adhesive face of the pressure-sensitive adhesive layer is laminated on the polarizing plate, and the release film or the like is peeled off from the state in which the release film or the like is laminated on the other adhesive face, for example, glass. It is obtained in the situation as used by bonding to the outer surface of a board | substrate. That is, since the adhesive sheet of this invention is excellent in antistatic performance, in the said situation, the quantity of the static electricity which arises when peeling a release film from an adhesive layer can be suppressed. As a result, undesirable effects on the liquid crystal display device caused by the generation of static electricity can be reduced.

Moreover, the adhesive sheet of this invention enables realization of the remarkable effect which was not achieved by the prior art that it is excellent also in durability under more stringent environmental conditions in addition to the said effect. Specifically, even in a harsh environment under high temperature (105 ° C or 115 ° C) or high temperature, high humidity, durability under strict conditions without peeling of the polarizing plate from the glass substrate or the like and foaming in the pressure-sensitive adhesive layer can be realized. In addition, the occurrence of white spots on the image display screen, which is likely to occur when the liquid crystal display device is used in a harsh environment, can also be suppressed. The polarizing plate which can use the adhesive sheet of this invention does not have a restriction | limiting in particular, It can use for sticking of a conventionally well-known polarizing plate. Specifically, for example, a polarizing plate coated with a discotic liquid crystal, or an uncoated polarizing plate or a stretched film, for example, a stretched triacetyl cellulose, in addition to a general polarizing plate (one using an untreated TAC film). The polarizing plate etc. which were based on the type film, the stretched polycycloolefin type film, or the stretched cellulose acetate propionate film are mentioned.

The adhesive sheet of this invention of the form in which the adhesive layer is formed on a release film etc. can be manufactured in the following procedure. The adhesive prescribed | regulated by this invention to release films, such as a polyethylene terephthalate film (PET film) which coated the peeling agent, such as a silicone resin, on the surface using the coating apparatus normally used, for example, a roll coating apparatus, etc. It can manufacture easily by apply | coating a composition and drying and forming an adhesive layer. And a polarizing plate may be bonded directly to the adhesive layer of the side without a release film, and after storing in the state in which the release film exists in both sides of an adhesive layer, you may peel off a release film as needed and bond to a polarizing plate. In any of the above cases, the constituent material of the pressure-sensitive adhesive composition can be cured by heat crosslinking or ultraviolet rays to form a pressure-sensitive adhesive layer as necessary.

The adhesive layer which comprises the adhesive sheet of this invention can be formed by the method mentioned above using the adhesive composition prescribed | regulated by this invention. In this case, the coating amount of the pressure-sensitive adhesive composition is preferably such that the thickness of the pressure-sensitive adhesive layer after drying is about 10 to 50 µm. The thickness of the adhesive layer after more preferable drying is about 10-25 micrometers. By carrying out thickness of an adhesive layer in the said range, it becomes a pressure-sensitive adhesive sheet more balanced with durability and antistatic property. And as mentioned above, the remarkable effect of this invention is acquired by sticking a polarizing plate on the glass substrate of a liquid crystal display device, for example by using the adhesive sheet of this invention as a means currently used.

EXAMPLE

Next, a production example, an Example, and a comparative example are given and this invention is demonstrated further more concretely. In addition, in a sentence, "part" and "%" are mass references | standards.

[Production Example 1]

(Production of Acrylic Copolymer)

80 parts of butyl acrylate (BA) is contained as 140 parts of ethyl acetate which is a reaction solvent after nitrogen gas is enclosed in the reaction apparatus provided with a stirrer, a thermometer, a reflux condenser, and a nitrogen inlet tube. and (a2) component, 20 parts of phenoxydiethylene glycol acrylate (made by Kyowa Co., Ltd., brand name "light acrylate P2HA") and (a3) component are hydroxyethyl acrylate (HEA) 2 parts and 0.05 parts of azobis isobutyronitrile as a polymerization initiator were added. It was made to react at 55 degreeC for 7 hours in nitrogen gas stream, stirring this. After the completion of the reaction, the mixture 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 to 18]

Except having used the component (a1)-(a3) used by the manufacture example 1 with the kind and quantity of Table 1 (Table 1-1, Table 1-2), respectively, it carried out similarly to manufacture example 1, and is used in an Example Acrylic copolymer composition solutions A2-A11 and acrylic copolymer composition solutions B1-B7 used by a comparative example were obtained.

The abbreviation in Table 1 is as follows.

BA: Butyl acrylate

MA: Methyl acrylate

P2HA: Phenoxy diethylene glycol acrylate: The product made in Kyocisha, brand name "light acrylate P2HA"

P-300A: Phenoxy triethylene glycol acrylate: The product made in Kyocisha, brand name "light acrylate P-300A"

FA-314A: Nonylphenoxy polyethyleneglycol acrylate: The product made by Hitachi Kasei Co., Ltd., a brand name "FA-314A"

FA-318A: nonylphenoxy polyethylene glycol acrylate: manufactured by Hitachi Kasei Co., Ltd., brand name "FA-318A"

PHEA: Phenoxyethyl acrylate manufactured by Kyoeisha Co., Ltd., trade name "light acrylate PO-A"

-EC-A: ethoxy diethylene glycol acrylate: The product made in Kyocisha, brand name "light acrylate EC-A"

FA-400M: methoxy polyethylene glycol # 400 methacrylate: The Hitachi Kasei Co., Ltd. brand name "FA-400M (100)"

HEA: hydroxyethyl acrylate

4HBA: 4-hydroxybutyl acrylate

AAC: acrylic acid

Β-CEA: β-carboxyethyl acrylate

GA: glycidyl acrylate

GMA: glycidyl methacrylate

4HBAGE: 4-hydroxybutyl acrylate glycidyl ether

AM: acrylamide

MAM: methacrylamide

DMAPAA: dimethylaminopropyl acrylamide

Table 1-1

TABLE 1-2

Example 1

(Preparation of Adhesive Composition)

About 100 parts of solid content of the acrylic copolymer composition solution A1 obtained above, coronate L (a brand name, the trimethylolpropane adduct of TDI by Nippon Polyurethane company, solid content concentration 75%) isocyanate type hardening | curing agent 0.50 part in solid content and 5.0 parts of ethylmethyl imidazolium bis (trifluoromethanesulfonyl) imide as an antistatic agent, As a silane coupling agent, X-41-1810 (brand name, Shin-Etsu Chemical Co., Ltd. make) ) Was added and the mixture was sufficiently mixed to obtain an adhesive composition 1.

(Production of Adhesive Sheet 1)

After apply | coating the adhesive composition 1 obtained above on PET film which is a release film coated with a silicone resin, the solvent was removed by drying at 90 degreeC, and the adhesive layer of 20 micrometers of dry thickness was formed. And after bonding the surface which formed this adhesive layer to one surface of a polarizing film, it cure | cures in 23 degreeC and 50% RH atmosphere for 7 days, and the adhesive sheet 1 which has a release film and an adhesive layer as a component An optical member was obtained.

Examples 2 to 20 and Comparative Examples 1 to 9

Instead of the acrylic copolymer composition solution A1 used in Example 1, in the type and amount shown in Table 2 (Table 2-1, Table 2-2, Table 2-3), acrylic copolymer composition solutions A1 to A11 for Examples. In the same manner as in Example 1, except that the acrylic copolymer composition solutions B1 to B7 for the comparative examples were used, the adhesive compositions 2 to 20 for the examples and the adhesive compositions 21 to 29 for the comparative examples were obtained. And except having used adhesive compositions 2-29, it carried out similarly to Example 1, and obtained adhesive sheets 2-20 of Examples 2-20, and adhesive sheets 21-29 of Comparative Examples 1-9, respectively.

TABLE 2-1

Table 2-2

TABLE 2-3

<Evaluation method>

1. Preparation (substrate: polarizing film) of polarizing plate of sample for evaluation

Using each adhesive composition produced in the Example and the comparative example, the adhesive layer was formed in the polarizing plate by the following method, and the polarizing plate of the adhesive layer part which is a sample for evaluation was produced. That is, after apply | coating adhesive compositions 1-29 on PET film (releasable base material) which is a release film coated with a silicone resin, the solvent was removed by drying at 90 degreeC, and the adhesive layer of thickness 20micrometer was formed. After bonding the 110-micrometer-thick polarizing film to the surface which formed this adhesive layer, the sample for evaluation was produced by curing for 7 days in 23 degreeC and 50% RH atmosphere, respectively. The size of the sample for evaluation was 80 mm x 150 mm, and the TAC polarizing plate was used for the said polarizing film. And each test mentioned later was performed using the sample for evaluation which the adhesive layer, the release film, and the polarizing film which were produced as mentioned above were laminated | stacked, and evaluated based on each evaluation criteria. And the result was shown in Table 3. Table 3-1 and Table 3-2 showed the result about the sample for evaluation of an Example, and the result about the sample for evaluation of a comparative example was shown in Table 3-3.

2. Durable

(1) durability at 105 ° C

Using each sample for evaluation, the mold release film was peeled off, the adhesive layer surface was exposed, and after sticking to glass, it was left to stand for 500 hours in 105 degreeC (DRY) atmosphere. After leaving, the foaming and peeling which arose in the adhesive layer were visually observed (10 times the loupe can be used. The same. Hereinafter.), It confirmed, evaluated with the following reference | standard, and the evaluation result was shown in Table 3.

(2) durability at 115 ° C

Using each sample for evaluation, the mold release film was peeled off, the adhesive layer surface was exposed, and after sticking to glass, it was left to stand for 500 hours in the atmosphere of 115 degreeC (DRY). After leaving, the foaming and peeling which arose in the adhesive layer were visually observed and confirmed, it evaluated by the following references | standards, and the evaluation result was shown in Table 3.

(3) Durability at 65 ° C and 95% RH

After attaching the sample for evaluation to glass and leaving it for 500 hours in 65 degreeC and 95% RH in the high temperature and high humidity atmosphere, visual observation is performed about foaming and peeling, and it confirms by the following references | standards, and evaluates in Table 3, The result was shown.

(Evaluation standard)

1) About firing

  (Circle): Foaming was not confirmed by the polarizing plate.

(Triangle | delta): Although foaming was recognized by the polarizing plate a little, it was a degree which is satisfactory practically.

  X: Foaming was confirmed to the polarizing plate.

2) About peeling

(Circle): Peeling to the polarizing plate was not confirmed.

(Triangle | delta): Although peeling was recognized slightly to a polarizing plate, it was a degree which is satisfactory practically.

X: Clear peeling was confirmed by the polarizing plate.

3. Adhesiveness

Adhesiveness was evaluated by the number of times until the adhesive layer surface of the sample for evaluation was rubbed 10 times with a finger, and fell out from a polarizing film (TAC polarizing plate). In addition, when falling out 1 to 9 times, the number of times was described, and when it rubbed 10 times, it was described as "> 10".

4. Surface resistance value

The separator of the sample for evaluation was peeled off, the adhesive layer surface was exposed, and the high resistivity meter (brand name: Hirester UX 'MCP-) made by Mitsubishi Chemical Analyzer under the room temperature conditions of temperature 23 +/- 2 degreeC and humidity 50 +/- 5% RH The surface resistance value ((ohm / square)) of the adhesive layer surface was measured using HT450) and a measuring electrode.

5. white spots

After affixing the sample for evaluation to glass, it used two sheets of the sample (it is possible even after the durability test in 65 degreeC 95% RH) left at the temperature of 65 degreeC 95% RH for 500 hours in the atmosphere of high temperature and humidity, and uses two sheets of liquid crystals, The upper and lower surfaces of the panel were bonded as cross nicol. The backlight of the liquid crystal monitor was turned on, the state of the white spot was visually observed, and the following reference | standard evaluated.

[Evaluation standard]

  (Circle): No white spot is observed in a polarizing plate.

(Triangle | delta): White spots were observed slightly in a polarizing plate.

X: White spots were observed on the polarizing plate.

6. Total evaluation

Total evaluation was performed based on the following criteria.

[Evaluation standard]

A: Evaluation of durability is (circle) about all the environmental conditions, evaluation of adhesiveness is ≥ 8, the surface resistance value of an adhesive layer is 4.0 * 10 <^9> ohm / square or less, and evaluation of a white spot is ○ If

B: Evaluation of durability is one of the environmental conditions, and foaming and / or peeling are recognized a little on a polarizing plate, evaluation of adhesiveness is ≧ 8, and the surface resistance of the pressure-sensitive adhesive layer is 4.0 × 10 ⁹ Ω. / / It is below, and when the evaluation of a white spot is (circle).

C: Evaluation of durability is one of the environmental conditions, and foaming and / or peeling are recognized a little on a polarizing plate, evaluation of adhesiveness is ≥ 8, and the surface resistance value of the pressure-sensitive adhesive layer is 4.0 × 10 ⁹ Ω. When it exceeds / /, it is less than 5.0x10 <^9> ohms / square, and evaluation of a white spot is (circle).

D: Evaluation of durability is one of the environmental conditions, and foaming and / or peeling are recognized by a polarizing plate, and evaluation of adhesiveness is <8,> 6, and the surface resistance value of an adhesive layer is 5.0 *. When less than 10 ⁹ ohms / square and evaluation of a white spot is (triangle | delta) or x.

E: It is one of the environmental conditions in any of evaluation of durability, foaming and / or peeling is recognized by a polarizing plate, evaluation of adhesiveness is <6, or the surface resistance value of an adhesive layer is 5.0x10 <^{9> (} ohm) / □ If abnormal.

Table 3-1

Table 3-2

Table 3-3

As shown to Table 3-1 and Table 3-2, the adhesive layer formed from the adhesive composition which comprises the adhesive sheet of an Example has a specific (a2) component as a monomer composition of an acrylic copolymer (A), this invention. By using it in the quantity prescribed | regulated to, it is clear from the comparison with Comparative Examples 1-6, 8, and 9, It is excellent in the durability under strict conditions which were not achieved by the prior art, and surface resistance value is 5.0x10. ^It has been confirmed that excellent antistatic performance that has not been realized yet can be realized at less than ⁹ Ω / □, less than 4.0 × 10 ⁹ Ω / □ in most embodiments, and even less than 3.0 × 10 ⁹ Ω / □. . Moreover, since the adhesive layer which comprises the adhesive sheet of the Example of this invention realizes sufficient adhesiveness and suppression of generation | occurrence | production of a white spot phenomenon which become an important characteristic in a polarizing plate, the utility value becomes very high.

Claims (5)

As an adhesive sheet for polarizing plate sticking which consists of a release film or a release paper, and an adhesive layer,
The said adhesive layer consists of an adhesive composition which contains an acryl-type copolymer (A), a hardening | curing agent (B), and an antistatic agent (C) at least,
The antistatic agent (C) includes a compound containing any one of fluorine or silicon in the structure, except that the compound represented by M ⁺ [(FSO ₂ ) ₂ N] ^- , where M is an alkali metal. In addition, it is added in the quantity of the range of 3.5 mass parts or more and less than 10 mass parts with respect to 100 mass parts of said acrylic copolymers (A),
The said acryl-type copolymer (A) contains 50 mass% or more and less than 85 mass% of at least 1 sort (s) of ethylenically unsaturated monomer (a1) in which a monomer composition does not have a reactive functional group, and is following General formula (1) It is more than 15 mass%, and contains 50 mass% or less of at least 1 sort (s) of the monomer (a2) represented by
A monomer containing at least one of ethylenically unsaturated monomers (a3) having a reactive functional group at 0.01 parts by mass or more and 5 parts by mass or less based on 100 parts by mass of the total amount of the monomer (a1) and the monomer (a2). Made by copolymerization,
The surface resistance of the said adhesive layer is 4.0 * 10 <^{9> (} ohm) / square or less, The adhesive sheet characterized by the above-mentioned.

(In general formula (1), R <^1> represents a hydrogen atom or a methyl group, R <^2> represents either a hydrogen atom, an alkyl group, an aralkyl group, or an aryl group, and either of n = 2-9. Is an integer.) The method of claim 1,
The adhesive sheet which is at least any one selected from the group which the reactive functional group of the ethylenically unsaturated monomer (a3) which has the said reactive functional group consists of a hydroxyl group, a carboxy group, a glycidyl group, and a nitrogen containing group. The method according to claim 1 or 2,
The said hardening | curing agent (B) contains an isocyanate type compound, and the adhesive sheet whose usage-amount exists in the range of 0.01 mass part or more and 10 mass parts or less with respect to 100 mass parts of said acrylic copolymers (A). The method according to claim 1 or 2,
The adhesive sheet which the said adhesive composition contains a silane coupling agent (D) further. The method according to claim 1 or 2,
The said adhesive composition contains a silane coupling agent (D) further, The said hardening | curing agent (B) contains an isocyanate type compound, The usage-amount is 0.01 mass part with respect to 100 mass parts of said acrylic copolymers (A). The adhesive sheet in the range of 10 mass parts or more and 10 mass parts or less.