KR20120056760A - Acrylic adhesive composition, acrylic adhesive and optical member having adhesive layer - Google Patents

Abstract

PURPOSE: An acrylic adhesive composition is provided to form an adhesive layer capable of preventing the generation of white stripe patterns due to the elongation of a polarizer, in case of using for a polarizer composing a liquid crystal display device, etc. CONSTITUTION: An acrylic adhesive composition comprises a first (meth)acrylate ester polymer of which weight average molecular weight is 1,000,000-2,500,000, a second (meth)acrylate ester polymer of which weight average molecular weight is 20,000-150,000, and an isocyanate based crosslinking agent. The second (meth)acrylate ester polymer is a triblock copolymer comprising a hydroxy group-containing (meth)acrylate-based monomer unit. The content of the second (meth)acrylate-based monomer unit is 40 parts by weight or less, on the basis of 100.0 parts by weight of the first (meth)acrylate-based monomer unit. The gel fraction of an adhesive consisting of the composition is 40% or more.

Description

Acrylic pressure sensitive adhesive composition, acrylic pressure sensitive adhesive and optical member with pressure sensitive adhesive layer {ACRYLIC ADHESIVE COMPOSITION, ACRYLIC ADHESIVE AND OPTICAL MEMBER HAVING ADHESIVE LAYER}

The present invention relates to an acrylic pressure-sensitive adhesive composition, an acrylic pressure-sensitive adhesive formed by heat crosslinking thereof, and an optical member with a pressure-sensitive adhesive layer. In more detail, this invention is used suitably for the polarizing plate which comprises a liquid crystal display device, and is for forming the adhesive layer which can prevent generation | occurrence | production of the white stripe phenomenon resulting from expansion and contraction of the said polarizing plate. An acrylic adhesive composition, the acrylic adhesive obtained from this, and this optical layer with an adhesive layer are related.

If the pressure-sensitive adhesive layer cannot absorb and relax the internal stress generated by the expansion and contraction of the polarizing plate, the distribution of the residual stress acting on the polarizing plate becomes nonuniform, and the stress concentrates particularly on the peripheral portion thereof. As a result, the peripheral edge portion of the liquid crystal display device becomes brighter than the center, which causes white streaks in the liquid crystal display device. As another factor in which white streaks occur in the liquid crystal display device, optical distortion (the occurrence of birefringence, etc.) generated in the optical functional film or the pressure-sensitive adhesive layer due to stress is considered.

Patent Document 1 discloses a pressure-sensitive adhesive composition for a polarizing plate composed of a high molecular weight acrylic copolymer, a low molecular weight acrylic copolymer having a weight average molecular weight of 30,000 or less, and a multifunctional compound, and the pressure-sensitive adhesive composition follows the dimensional change of the polarizing plate. It is described that white streaks are less likely to occur. However, in the adhesive composition of patent document 1, since the content of the low molecular weight acrylic copolymer whose weight average molecular weight is 30,000 or less is large, it is difficult to prevent foaming and peeling under high temperature and high humidity [Comparative Example 2].

Patent Document 2 discloses a mixture of a low glass transition temperature (Tg) acrylic copolymer having a functional group-containing monomer of 0.5% by weight or less and a high Tg acrylic copolymer having a functional group-containing monomer of 6% by weight or more, and an isocyanate of a crosslinking agent that can react with the functional group. An adhesive composition having a gel fraction of less than 30% by weight of a nate compound is disclosed. This adhesive composition forms a crosslinked structure in the molecule | numerator of a high Tg acryl-type copolymer, and expresses cohesion force by restraining the molecule | numerator of a low Tg acryl-type copolymer with the multimer of an isocyanate compound. However, since this crosslinking structure is hardly formed in this molecule | numerator, it is hard to produce a white stripe, but cohesion force under high temperature is low, and it is difficult to suppress foaming and generation | occurrence | production of peeling in durability evaluation.

Patent Literature 3, 1 to 100 parts by weight of the acrylic oligomer composed of 100 parts by weight of the adhesive polymer containing the acrylic polymer as a main component, and a block copolymer containing a polymer block having a glass transition temperature of -5 ° C. or less. The pressure-sensitive adhesive composition, characterized in that made. The acrylic oligomer includes a polymer block having a glass transition temperature of -5 ° C or less at its own, and thus has an adhesive force such that it does not peel off from the adherend when it is fixed to the adherend, Raising of the adhesive force hardly occurs, and at the time of peeling from the adherend, peeling can be performed very easily without contaminating the adherend. Moreover, by making it into a copolymer with the polymer block from which a monomer composition differs from this, the said effect can be exhibited even if use of a small acryl-type oligomer is carried out. Although the detail is unknown about the reason why such an excellent effect is exhibited, it is thought that the said characteristic, such as adhesive force and peeling force, can be exhibited by the effect of the compatibility with acrylic polymer improved by the synergistic effect of each block. It is described. However, since the oligomer component exists in a free state, durability under wet heat conditions was inferior (Comparative Example 3).

JP 3533589 B JP 2006-133606 A JP 4092152 B

The present invention has been made under such a situation, and an acrylic pressure-sensitive adhesive for forming a layer made of a pressure-sensitive adhesive which is suitably used for a polarizing plate constituting a liquid crystal display device and can prevent occurrence of white streaks due to expansion and contraction of the polarizing plate. It is an object of the present invention to provide an acrylic pressure-sensitive adhesive having the composition and the properties obtained therefrom.

MEANS TO SOLVE THE PROBLEM The present inventors obtained the following knowledge as a result of earnestly researching in order to achieve the said objective.

A high molecular weight first (meth) acrylic acid ester polymer having a weight average molecular weight in a specific range, a low molecular weight second (meth) acrylic acid ester polymer having a weight average molecular weight in a specific range, and an isocyanate-based crosslinking agent In the pressure-sensitive adhesive composition comprising, the second (meth) acrylic acid ester polymer is a triblock copolymer having a hydroxyl group-containing (meth) acrylate monomer unit, and thermally crosslinked to contain a specific ratio thereof. The hydroxyl group in the low molecular weight triblock copolymer becomes a crosslinking point and crosslinking occurs.

As a result, the high-molecular weight first (meth) acrylic acid ester polymer penetrates into the three-dimensional network structure formed by crosslinking of the low molecular weight triblock copolymer, thereby causing internal stress caused by expansion and contraction of optical members such as polarizing plates. It is estimated that it can absorb and alleviate effectively.

In addition, it was found that by setting the gel fraction of the pressure-sensitive adhesive formed by the pressure-sensitive adhesive composition to 40% or more, the cohesive force necessary for optical use can be imparted to the pressure-sensitive adhesive while maintaining the absorption and relaxation of the internal stress.

The present invention has been completed based on these findings.

That is, the present invention,

[1] The first (meth) acrylic acid ester polymer (A) having a weight average molecular weight of 1 million to 2.5 million, the second (meth) acrylic acid ester polymer (B) having a weight average molecular weight of 20,000 to 150,000, and iso As an adhesive composition containing a cyanate crosslinking agent (C),

(1) the second (meth) acrylic acid ester polymer (B) is a triblock copolymer having a hydroxyl group-containing (meth) acrylate monomer unit,

(2) Content of said 2nd (meth) acrylic acid ester polymer (B) is less than 40 mass parts with respect to 100 mass parts of said 1st (meth) acrylic acid ester polymers (A), and

(3) The gel fraction of the pressure-sensitive adhesive formed of the pressure-sensitive adhesive composition is 40% or more

Acrylic pressure-sensitive adhesive composition characterized in that;

[2] The form of the triblock copolymer is b2-b1-b2 or b1-b2-b1 (where b1 represents a block composed of (meth) acrylate monomer units having no functional group as a crosslinking point, b2 represents a block composed of a hydroxyl group-containing (meth) acrylate monomer unit), the acrylic pressure-sensitive adhesive composition according to the above item [1];

[3] The acrylic pressure sensitive adhesive composition according to the above [1] or [2], wherein a ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the triblock copolymer is 1.0 to 1.8;

[4] The content of the hydroxyl group-containing (meth) acrylate monomer unit in the triblock copolymer is 1.5 to 20% by mass, and the content of the triblock copolymer is the first (meth) acrylic acid ester polymer (A) The acrylic adhesive composition in any one of said [1]-[3] which is 10-30 mass parts with respect to 100 mass parts;

[5] The acrylic pressure sensitive adhesive composition according to any one of [1] to [4], wherein the triblock copolymer is formed by living radical polymerization;

[6] The item of any of the above [1] to [5], wherein the content of the isocyanate-based crosslinking agent (C) is 5 to 20 parts by mass with respect to 100 parts by mass of the second (meth) acrylic acid ester polymer (B). Acrylic adhesive composition of description;

[7] an acrylic pressure sensitive adhesive, wherein the acrylic pressure sensitive adhesive composition according to any one of [1] to [6] is thermally crosslinked; And

[8] An optical member with a pressure-sensitive adhesive layer is provided by laminating the acrylic pressure-sensitive adhesive according to the above [7] in a layered shape on the optical member.

According to the present invention, an acrylic pressure-sensitive adhesive composition for forming a pressure-sensitive adhesive layer which is suitably used for a polarizing plate constituting a liquid crystal display device and can prevent the occurrence of white streaks due to expansion and contraction of the polarizing plate, an acrylic pressure-sensitive adhesive obtained therefrom, and An optical member with an adhesive layer can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which showed the method of evaluating the light leakage prevention property of the polarizing plate with an adhesive layer obtained by the Example and the comparative example.

First, the acrylic adhesive composition of this invention is demonstrated.

ACRYLIC PRESSURE COMPOSITION

The acrylic pressure-sensitive adhesive composition (hereinafter sometimes referred to only as "adhesive composition") of the present invention has a first (meth) acrylic acid ester polymer (A) having a weight average molecular weight of 1 million to 2.5 million, and a weight average molecular weight of 2 As an adhesive composition containing the 2nd (meth) acrylic acid ester polymer (B) which is 10,000-150,000, and an isocyanate type crosslinking agent (C),

(1) the second (meth) acrylic acid ester polymer (B) is a triblock copolymer having a hydroxyl group-containing (meth) acrylate monomer unit,

(2) Content of said 2nd (meth) acrylic acid ester polymer (B) is less than 40 mass parts with respect to 100 mass parts of said 1st (meth) acrylic acid ester polymers (A), and

(3) The gel fraction of the pressure-sensitive adhesive formed of the pressure-sensitive adhesive composition is 40% or more

.

The pressure-sensitive adhesive obtained by the pressure-sensitive adhesive composition is similar to the polymer (A) by forming a three-dimensional network structure by the polymer (B) and the crosslinking agent (C), and inserting two or more polymers (A) in the three-dimensional network structure. It is assumed that a crosslinked structure is formed. That is, since most of the polymers (A) are connected by a pseudo crosslinked structure via the above three-dimensional network structure rather than a chemically crosslinked structure, the mobility of the crosslinked portion is higher than that by chemical crosslinking. It is estimated to be large. For this reason, the pressure-sensitive adhesive formed is rich in stress relaxation properties.

Moreover, in this invention, by arrange | positioning the crosslinking point in a polymer (B) block-wise, the size of the mesh | network of the said three-dimensional network structure of the adhesive formed can be adjusted so that it may become optimal, and by this, in a high dimension It is estimated that both the improvement of stress relaxation property and the improvement of cohesion force are implement | achieved.

(First (meth) acrylic acid ester polymer (A))

In the acrylic pressure-sensitive adhesive composition of the present invention, as the first (meth) acrylic acid ester polymer used as the component (A), it is preferable to use (meth) acrylate monomers having no reactive functional group as the main constituent components. Although the 1st said polymer may be comprised only with the (meth) acrylate type monomer which does not have a reactive functional group, in consideration of adhesiveness to glass surfaces, such as a liquid crystal glass cell, etc., the (meth) acrylate type monomer which has a carboxyl group is considered. It is more preferable to copolymerize a small amount.

There is no restriction | limiting in particular as a (meth) acrylate type monomer which does not have a reactive functional group, For example, the (meth) acrylic acid ester whose carbon number of the alkyl group of an ester part is 1-20 is preferable. Here, as an example of the (meth) acrylic acid ester whose carbon number of the alkyl group of an ester part is 1-20, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate Hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, and dimethyl (meth) acrylate , Palmityl (meth) acrylate, stearyl (meth) acrylate, and the like. These may be used independently and may be used in combination of 2 or more type.

Among these compounds, butyl acrylate is particularly preferred in that a suitable adhesion performance can be obtained and a (meth) acrylic acid ester copolymer having a weight average molecular weight of 1 million or more can be easily produced.

On the other hand, (meth) acrylic acid, crotonic acid, maleic acid, itaconic acid, a citraconic acid etc. are mentioned as a specific example of the carboxyl group-containing (meth) acrylate type monomer mix | blended as needed. Although these may be used individually by 1 type and may be used in combination of 2 or more type, acrylic acid is preferable at the point which can manufacture easily the (meth) acrylic acid ester copolymer of 1 million or more in weight average molecular weight among these. .

Moreover, reactive functional group containing other than carboxyl group containing (meth) acrylate type monomers, such as a hydroxyl group containing (meth) acrylate type monomer, an amino group containing (meth) acrylate type monomer, and a thiol group containing (meth) acrylate type monomer ( It is preferable that a meta) acrylate type monomer is not contained as a structural unit of a 1st (meth) acrylic acid ester polymer (A). This is because the formation of a three-dimensional network structure by the second (meth) acrylic acid ester polymer (B) and the isocyanate-based crosslinking agent (C) may be inhibited.

As another functional group containing monomer, non-crosslinkable acrylamide, such as (meth) acrylic acid ester, acrylamide, and methacrylamide which have aromatic rings, such as phenyl (meth) acrylate, N, N- dimethylaminoethyl (meth) acrylate And (meth) acrylic acid ester, vinyl acetate, styrene etc. which have non-crosslinkable tertiary amino groups, such as (meth) acrylic acid N, N- dimethylaminopropyl, These are the range which does not impair the effect of this invention. Can be used as appropriate.

In the said 1st (meth) acrylic acid ester polymer, the content rate of the (meth) acrylate type monomer unit which does not have a reactive functional group, and a carboxyl group-containing (meth) acrylate type monomer unit is from a rework property viewpoint. It is preferable to exist in the range of 100: 0-80:20 by mass ratio, and in addition to the said viewpoint, it is more preferable to exist in the range of 98: 2-90:10 from a viewpoint of durability.

Moreover, the said 1st (meth) acrylic acid ester polymer (A) does not need to be obtained by living radical polymerization like (B) component mentioned later, and may be obtained by a normal radical polymerization method. Here, the weight average molecular weight (Mw) of the said polymer (A) needs to be 1 million-2.5 million. It is because durability may fall when the said weight average molecular weight is less than 1 million, and stress relaxation property is inhibited when this weight average molecular weight exceeds 2.5 million, and light leakage prevention property may fall. From a similar viewpoint, the said weight average molecular weight becomes like this. Preferably it is the range of 1.2 million-2 million, More preferably, it is the range of 1.4 million-1.8 million.

In addition, the said weight average molecular weight is the polystyrene conversion value measured by the gel permeation chromatography (GPC) method.

In the adhesive composition of this invention, as a component (A), 1st (meth) acrylic acid ester polymer may be used individually by 1 type, and may be used in combination of 2 or more type.

(2nd (meth) acrylic acid ester polymer (B))

In the acrylic pressure-sensitive adhesive composition of the present invention, the second (meth) acrylic acid ester polymer used as the component (B) needs to be a triblock copolymer having a hydroxyl group-containing (meth) acrylate monomer unit.

The form of this triblock copolymer is b2-b1-b2 or b1-b2-b1 (where b1 represents a block composed of (meth) acrylate monomer units having no reactive functional group, and b2 contains a hydroxyl group) It represents a block consisting of (meth) acrylate monomer units).

The triblock copolymer of the said component (B) uses the (meth) acrylate type monomer which does not have a reactive functional group as a raw material component, and the hydroxyl group containing (meth) acrylate type monomer which has a hydroxyl group which is a reactive functional group.

In addition, in this invention, a block copolymer means the copolymer which has a block part which consists of a (meth) acrylate type monomer which does not have a reactive functional group, and a block part which consists of a hydroxyl group containing (meth) acrylate type monomer, Each block portion may be composed of plural kinds of monomers, and in the block portion, plural kinds of monomers may be arranged in blocks or randomly. However, in view of the control of the three-dimensional network structure, the block portion made of a (meth) acrylate monomer not having a reactive functional group and the block portion made of a hydroxyl group-containing (meth) acrylate monomer are each one of the same. It is preferable that it is comprised only by the monomer.

There is no restriction | limiting in particular as a (meth) acrylate type monomer which does not have a reactive functional group, For example, the (meth) acrylic acid ester whose carbon number of the alkyl group of an ester part is 1-20 is preferable. Here, as an example of the (meth) acrylic acid ester whose carbon number of the alkyl group of an ester part is 1-20, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate Hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, and dimethyl (meth) acrylate , Palmityl (meth) acrylate, stearyl (meth) acrylate, and the like. These may be used independently and may be used in combination of 2 or more type.

Among these compounds, in particular, butyl acrylate is preferred in view of good polymerizability and the ability to obtain appropriate adhesion performance.

In addition, as a specific example of a hydroxyl-containing (meth) acrylate type monomer, (meth) acrylic-acid 2-hydroxyethyl, (meth) acrylic-acid 2-hydroxypropyl, (meth) acrylic-acid 3-hydroxypropyl, (meth) acrylic acid 2 (Meth) acrylic-acid hydroxyalkyl esters, such as -hydroxy butyl, (meth) acrylic acid 3-hydroxybutyl, and (meth) acrylic acid 4-hydroxybutyl, etc. are mentioned. These may be used independently and may be used in combination of 2 or more type. Among these, 2-hydroxyethyl acrylate, 3-hydroxypropyl acrylate, and 4-hydroxybutyl acrylate are more preferable. This is because the hydroxyl group which becomes a crosslinking point when incorporated in the polymer (B) is less likely to be limited in contact with the crosslinking agent (C) by adjacent carbon atoms or side chain portions.

The triblock copolymer of the said component (B) needs that a weight average molecular weight exists in the range of 20,000-150,000.

By thermally crosslinking the pressure-sensitive adhesive composition containing such a low molecular weight thermocrosslinkable triblock copolymer, the hydroxyl group in the low molecular weight triblock copolymer becomes a crosslinking point and crosslinking occurs between the triblock copolymers.

As a result, the 1st (meth) acrylic acid ester polymer which is the high molecular weight mentioned above invades in the three-dimensional network structure formed by crosslinking of the low molecular weight triblock copolymer, and it arises by expansion | contraction of optical members, such as a polarizing plate. It is considered that the internal stress can be effectively absorbed and relaxed.

The weight average molecular weight of the triblock copolymer is preferably 2.50,000 to 120,000, more preferably 30,000 to 100,000. In addition, it is preferable that the ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn), ie, the molecular weight distribution (PDI), is 1.0 to 1.8 from the viewpoint of achieving uniformity of the obtained three-dimensional network structure. Do.

In addition, the weight average molecular weight (Mw) and number average molecular weight (Mn) of the said triblock copolymer are standard polystyrene conversion values measured by the gel permeation chromatography method (GPC method).

<Production of Triblock Copolymer>

The triblock copolymer can be effectively prepared by living radical polymerization.

It is estimated by this that the size of the mesh of the three-dimensional network structure formed by the polymer (B) and a crosslinking agent (C) can be adjusted to the preferable range in which the polymer (A) is restrained with some degree of freedom. Therefore, it becomes possible to obtain the adhesive which has abundant stress relaxation property and has the outstanding cohesion force.

Moreover, by using living radical polymerization, since the length of the molecular chain of a polymer (B) can be adjusted and arrangement | positioning of a crosslinking site can be made constant, it is estimated that a uniform three-dimensional network structure can be arrange | positioned in the adhesive obtained. . Thereby, the realization of the uniform stress relaxation property with the whole adhesive is anticipated.

As a living radical polymerization method, a conventionally well-known method, for example, the atom transfer radical polymerization method (ATRP polymerization method) which uses an atomic transfer radical polymerization agent as a polymerization control agent, the reversible addition-cracking using a reversible addition-breaking chain transfer agent The polymerization method by chain transfer (RAFT polymerization method), the polymerization method using an organic tellurium compound, etc. as a polymerization initiator can be employ | adopted. Among these living radical polymerization methods, the method of using an organic tellurium compound as a polymerization initiator is preferable because of the controllability of molecular weight, the thing which can superpose | polymerize also in aqueous system, etc. Below, the method of using an organic tellurium compound as a polymerization initiator is shown.

<< Living radical polymerization using organic tellurium compound >>

The second (meth) acrylic acid ester polymer (B) [triblock copolymer] may be referred to as a living radical polymerization initiator (hereinafter, referred to as "organic tellurium compound"), for example, represented by the following general formula (1). ) Can be produced by copolymerizing a (meth) acrylate monomer having no reactive functional group and a hydroxyl group-containing (meth) acrylate monomer in a predetermined order.

[Formula 1]

[In formula, R <^1> represents a C1-C8 alkyl group, an aryl group, a substituted aryl group, or an aromatic heterocyclic group. R ² and R ³ represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. R ⁴ represents an aryl group, a substituted aryl group, an aromatic heterocyclic group, an acyl group, an oxycarbonyl group or a cyano group.]

The group represented by R ¹ is specifically as follows.

Examples of the alkyl group having 1 to 8 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, cyclopropyl group, n-butyl group, sec-butyl group, tert-butyl group, cyclobutyl group, n-pentyl group, n C1-C8 linear, branched, or cyclic alkyl groups, such as -hexyl group, n-heptyl group, and n-octyl group, are mentioned. As a preferable alkyl group, a C1-C4 linear or branched alkyl group, More preferably, a methyl group or an ethyl group is mentioned.

As an aryl group, a pyridyl group, a furyl group, thienyl group, etc. are mentioned as an aromatic heterocyclic group, such as a phenyl group which has a substituent, a naphthyl group which has a substituent, etc. as a substituted aryl group, such as a phenyl group and a naphthyl group. As a substituent of the aryl group which has the said substituent, For example, a halogen atom, a hydroxyl group, an alkoxy group, an amino group, a nitro group, a cyano group, the carbonyl containing group represented by -COR <^5> (R < ⁵ > -C1-C5) 8 alkyl groups, aryl groups, alkoxy groups having 1 to 8 carbon atoms, aryloxy groups), sulfonyl groups, trifluoromethyl groups and the like. As a preferable aryl group, a phenyl group and a trifluoromethyl substituted phenyl group are mentioned. Moreover, those substituted by one or two are mentioned, These substituents are preferably a para position or an ortho position.

Each group represented by R ² and R ³ is specifically as follows.

Examples of the alkyl group having 1 to 8 carbon atoms include the same alkyl group represented by R ¹ .

Each group represented by R ⁴ is specifically as follows.

Examples of the aryl group, substituted aryl group, and aromatic heterocyclic group include the same groups as those represented by R ¹ .

As acyl group, a formyl group, an acetyl group, a benzoyl group, etc. are mentioned. As the oxycarbonyl group, a group represented by -COOR ⁶ (R ⁶ = H, an alkyl group having 1 to 8 carbon atoms, an aryl group) is preferable, and for example, a carboxyl group, a methoxycarbonyl group, an ethoxycarbonyl group, propoxy Carbonyl group, n-butoxycarbonyl group, sec-butoxycarbonyl group, tert-butoxycarbonyl group, n-pentoxycarbonyl group, phenoxycarbonyl group, etc. are mentioned. As a preferable oxycarbonyl group, a methoxycarbonyl group and an ethoxycarbonyl group are mentioned.

As each group represented by preferable R <^4> , an aryl group, a substituted aryl group, and an oxycarbonyl group are mentioned. A phenyl group is mentioned as a preferable aryl group. As a preferable substituted aryl group, a halogen atom substituted phenyl group and a trifluoromethyl substituted phenyl group are mentioned. Moreover, in the case of a halogen atom, these substituents are preferable to substitute 1-5 pieces. In the case of an alkoxy group or a trifluoromethyl group, it is preferable to substitute one or two, in the case of one substitution, a para position or an ortho position is preferable, and in the case of two substitution, a meta position is preferable. . Preferred oxycarbonyl groups include methoxycarbonyl group and ethoxycarbonyl group.

As the organic tellurium compound I represented by general formula (1), R ¹ represents an alkyl group having 1 to 4 carbon atoms, R ² and R ³ represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R ⁴ is an aryl group, The compound represented by a substituted aryl group and an oxycarbonyl group is shown. Especially preferably, R ¹ represents an alkyl group having 1 to 4 carbon atoms, R ² and R ³ represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ⁴ represents a phenyl group, a substituted phenyl group, a methoxycarbonyl group or an ethoxy group. A carbonyl group is shown.

The organic tellurium compound represented by General formula 1 is as follows specifically ,.

Examples of the organic tellurium compound include (methylteranyl-methyl) benzene, (1-methylteranyl-ethyl) benzene, (2-methylteranyl-propyl) benzene, and 1-chloro-4- (methylteranyl-methyl) Benzene, 1-hydroxy-4- (methylteranyl-methyl) benzene, 1-methoxy-4- (methylteranyl-methyl) benzene, 1-amino-4- (methylteranyl-methyl) benzene, 1 Nitro-4- (methylteranyl-methyl) benzene, 1-cyano-4- (methylteranyl-methyl) benzene, 1-methylcarbonyl-4- (methylteranyl-methyl) benzene, 1- Phenylcarbonyl-4- (methylteranyl-methyl) benzene, 1-methoxycarbonyl-4- (methylteranyl-methyl) benzene, 1-phenoxycarbonyl-4- (methylteranyl-methyl) benzene , 1-sulfonyl-4- (methylteranyl-methyl) benzene, 1-trifluoromethyl-4- (methylteranyl-methyl) benzene, 1-chloro-4- (1-methylteranyl-ethyl) Benzene, 1-hydroxy-4- (1-methylteranyl-ethyl) benzene, 1-methoxy-4- (1-methylteranyl-ethyl) benzene, 1-amino-4- (1-methylteranyl -Ethyl) benzene, 1-nitro-4- (1-methylteranyl-ethyl) benzene, 1-Cyano-4- (1-methylteranyl-ethyl) benzene, 1-methylcarbonyl-4- (1-methylteranyl-ethyl) benzene, 1-phenylcarbonyl-4- (1-methylterra Neyl-ethyl) benzene, 1-methoxycarbonyl-4- (1-methylteranyl-ethyl) benzene, 1-phenoxycarbonyl-4- (1-methylteranyl-ethyl) benzene, 1-sulfonyl -4- (1-methylteranyl-ethyl) benzene, 1-trifluoromethyl-4- (1-methylteranyl-ethyl) benzene [1- (1-methylteranyl-ethyl) -4-trifluoro Romethylbenzene], 1- (1-methylteranyl-ethyl) -3,5-bistrifluoromethylbenzene, 1,2,3,4,5-pentafluoro-6- (1-methylteranyl -Ethyl) benzene, 1-chloro-4- (2-methylteranyl-propyl) benzene, 1-hydroxy-4- (2-methylteranyl-propyl) benzene, 1-methoxy-4- (2- Methylteranyl-propyl) benzene, 1-amino-4- (2-methylteranyl-propyl) benzene, 1-nitro-4- (2-methylteranyl-propyl) benzene, 1-cyano-4- (2-methylteranyl-propyl) benzene, 1-methylcarbonyl-4- (2-methylteranyl-propyl) benzene, 1-phenylcarbonyl-4- (2-methylte Ranyl-propyl) benzene, 1-methoxycarbonyl-4- (2-methylteranyl-propyl) benzene, 1-phenoxycarbonyl-4- (2-methylteranyl-propyl) benzene, 1-sulfonyl -4- (2-methylteranyl-propyl) benzene, 1-trifluoromethyl-4- (2-methylteranyl-propyl) benzene, 2- (methylteranyl-methyl) pyridine, 2- (1- Methylteranyl-ethyl) pyridine, 2- (2-methylteranyl-propyl) pyridine, 2-methyl-2-methylteranyl-propanal, 3-methyl-3-methylteranyl-2-butanone, 2 Methyl methyl teranyl carbonate, methyl 2-methylteranylpropionate, methyl 2-methylteranyl-2-methylpropionate, ethyl 2-methylteranyl- ethane, ethyl 2-methylteranyl-propionate, 2-methyl Teraneyl-2-methylpropionate ethyl [ethyl-2-methyl-2-methylteranyl-propionate], 2- (n-butylterranyl) -2-methylpropionate ethyl [ethyl-2-methyl-2- n-butylteranyl-propionate], 2-methylteranyl acetonitrile, 2-methylteranyl propionitrile, 2-methyl-2-methylteranyl And the like - (2-phenyl-propyl TB carbonyl) benzene as piohnayi Trill, (phenyl TB carbonyl-methyl) benzene, (1-phenyl TB carbonyl) benzene.

In the above, the methyl teranyl, 1-methyl teranyl, 2-methyl teranyl portion is ethyl teranyl, 1-ethyl teranyl, 2-ethyl teranyl, butyl teranyl, 1-butyl teranyl, All compounds modified with 2-butylterranyl are also included. Preferably, (methylteranyl-methyl) benzene, (1-methylteranyl-ethyl) benzene, (2-methylteranyl-propyl) benzene, 1-chloro-4- (1-methylteranyl-ethyl) Benzene, 1-trifluoromethyl-4- (1-methylteranyl-ethyl) benzene [1- (1-methylteranyl-ethyl) -4-trifluoromethylbenzene], 2-methylteranyl-2 -Methyl methyl propionate, 2-methylteranyl-2-methylpropionate [ethyl-2-methyl-2-methylteranyl-propionate], 2- (n-butylteranyl) -2-methylpropionate [ Ethyl-2-methyl-2-n-butylteranyl-propionate], 1- (1-methylteranyl-ethyl) -3,5-bistrifluoromethylbenzene, 1,2,3,4, 5-pentafluoro6- (1-methylteranyl-ethyl) benzene, 2-methylteranylpropionitrile, 2-methyl-2-methylteranylpropionitrile, (ethylteranyl-methyl) benzene, ( 1-ethylteranyl-ethyl) benzene, (2-ethylteranyl-propyl) benzene, 2-ethylteranyl-2-methylpropionic acid, 2-ethylteranyl-2-methylpropionic acid Ethyl, 2-ethylteranylpropionitrile, 2-methyl-2-ethylteranylpropionitrile, (n-butylteranyl-methyl) benzene, (1-n-butylteranyl-ethyl) benzene, (2 -n-butylteranyl-propyl) benzene, methyl 2-n-butylteranyl-2-methylpropionate, ethyl 2-n-butylteranyl-2-methylpropionate, 2-n-butylteranylpropionitrile, 2-methyl-2-n-butyl teranyl propionitrile is mentioned.

The organic tellurium compound represented by these General formula 1 may be used individually by 1 type, and may be used in combination of 2 or more type.

In the polymerization process in this invention, in addition to the said organic tellurium compound, you may add an azo polymerization initiator as a polymerization promoter. The azo-based polymerization initiator is not particularly limited as long as it is an initiator used for ordinary radical polymerization. Examples thereof include 2,2'-azobis (isobutyronitrile) (AIBN) and 2,2'-azobis (2-methyl). Butyronitrile) (AMBN), 2,2'-azobis (2,4-dimethylvaleronitrile) (ADVN), 1,1'-azobis (1-cyclohexanecarbonitrile) (ACHN) , Dimethyl-2,2'-azobisisobutyrate (MAIB), 4,4'-azobis (4-cyanovaleric acid) (ACVA), 1,1'-azobis (1-acetoxy- 1-phenylethane), 2,2'-azobis (2-methylbutylamide), 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2 ' Azobis (2-methylamidinopropane) dihydrochloride, 2,2'-azobis [2- (2-imidazolin-2-yl) propane], 2,2'-azobis [2-methyl- N- (2-hydroxyethyl) propionamide], 2,2'-azobis (2,4,4-trimethylpentane), 2-cyano-2-propylazoformamide, 2,2'-azo Bis (N-butyl-2- Til propionamide), and the like can be mentioned 2,2'-azobis (N- cyclohexyl-2-methyl propionamide).

When using the said azo polymerization initiator, Preferably it is 0.01-100 mol, More preferably, it is 0.1-100 mol, More preferably, 0.1-5 mol with respect to 1 mol of the organic tellurium compounds of General formula 1 used as a polymerization initiator. It is preferable to use in proportion.

The method of forming the said 2nd (meth) acrylic acid ester polymer (B) [triblock copolymer] by living radical polymerization is as follows specifically ,.

In a vessel substituted with an inert gas, the hydroxyl group-containing (meth) acrylate monomer and the living radical polymerization initiator represented by the general formula (1) and, if necessary, an azo polymerization initiator are mixed to carry out a polymerization reaction. At this time, as an inert gas, nitrogen, argon, helium, etc. are mentioned, Preferably, argon and nitrogen are mentioned, Especially preferably, it is nitrogen.

Next, after adding the (meth) acrylate type monomer which does not have a functional group used as a crosslinking point to a reaction system, and performing a polymerization reaction, a hydroxyl group containing (meth) acrylate type monomer is added and a polymerization reaction is performed, b2. -b1-b2 type (where b1 represents a block composed of (meth) acrylate monomer units having no functional group serving as a crosslinking point, and b2 represents a block composed of hydroxyl group-containing (meth) acrylate monomer units) The triblock copolymer of is obtained.

In addition, by making the order of a polymerization reaction into the (meth) acrylate type monomer which does not have a reactive functional group, the (meth) acrylate type monomer which contains a hydroxyl group, and the (meth) acrylate type monomer which does not have a reactive functional group, it becomes b1-b2-. Triblock copolymer of type b1 is obtained.

Although superposition | polymerization is normally performed in a solvent-free, you may use the organic solvent generally used in radical polymerization. Examples of the solvent that can be used include benzene, toluene, N, N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), acetone, chloroform, carbon tetrachloride, tetrahydrofuran (THF), ethyl acetate, Trifluoromethylbenzene, etc. are mentioned. Moreover, an aqueous solvent can also be used, For example, water, methanol, ethanol, isopropanol, n-butanol, ethyl cellosolve, butyl cellosolve, 1-methoxy-2-propanol, etc. are mentioned. . The amount of the solvent may be appropriately adjusted. For example, the solvent may be used in an amount of 0.01 to 100 ml, preferably 0.05 to 10 ml, and particularly preferably 0.05 to 0.5 ml with respect to 1 g of the monomer.

The molecular weight of the triblock copolymer obtained can be adjusted by reaction temperature, reaction time, and the quantity of the organic tellurium compound of General formula (1). Although reaction temperature and reaction time may be suitably adjusted with the molecular weight or molecular weight distribution of the triblock copolymer obtained, normally, 60 to 150 degreeC, and the total reaction time is about 5 to 100 hours. Preferably, at 80-120 degreeC, the total reaction time is about 10 to 30 hours. At this time, the pressure is usually performed at normal pressure, but may be pressurized or reduced in pressure.

After completion | finish of reaction, the target triblock copolymer is refine | purified by removing a used solvent and a residual monomer under reduced pressure, precipitation filtration, reprecipitation, or column separation by a conventional method.

In the adhesive composition of this invention, as a component (B), 2nd (meth) acrylic acid ester polymer [triblock copolymer] may contain individually 1 type, and may contain it in combination of 2 or more type. . Content of a component (B) needs to be less than 40 mass parts with respect to 100 mass parts of 1st (meth) acrylic acid ester polymers (A) mentioned above. It is because stress relaxation property may be inhibited when it is 40 mass parts or more. In addition to the said stress relaxation property, content of the component (B) with respect to 100 mass parts of said polymers (A) from a viewpoint of providing sufficient cohesion force to the adhesive obtained is preferably 5-30 mass parts, More preferably, Is 10-25 mass parts.

Moreover, it is preferable that content of the hydroxyl-containing (meth) acrylate type monomer unit in the said triblock copolymer is 1.5-20 mass% from a viewpoint of the performance of the adhesive composition obtained, and it is 5-15 mass% More preferred.

(Isocyanate-based crosslinking agent (C))

In the pressure-sensitive adhesive composition of the present invention, the isocyanate-based crosslinking agent to be contained as component (C) contains a hydroxyl group in the second (meth) acrylic acid ester polymer (B) [triblock copolymer] described above (meth The hydroxyl group of the acrylate-based monomer unit is used as a crosslinking point to crosslink the low molecular weight triblock copolymer to form a three-dimensional network structure.

Moreover, when a 1st (meth) acrylic acid ester polymer has a carboxyl group-containing (meth) acrylate type monomer unit, the said carboxyl group is made into a crosslinking point, and the said (meth) acrylic acid ester polymer of the said high molecular weight is Contribution to the crosslinking is also contemplated. However, the isocyanate-based crosslinking agent (C) is more reactive than the carboxyl group because the reactivity with the hydroxyl group is large, and therefore, most of the isocyanate-based crosslinking agent (C) is consumed due to the reaction with the hydroxyl group of the polymer (B). It is assumed that the reaction with the carboxyl group of the polymer (A) is very small.

The isocyanate crosslinking agent (C) contains a polyisocyanate compound, and examples of the polyisocyanate compound include tolylene diisocyanate, diphenylmethane diisocyanate and xyl. Aromatic polyisocyanates such as reylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate and the like Alicyclic polyisocyanates and the like, and their biuret bodies, isocyanurate bodies, and low molecular weight active hydrogens such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, castor oil, etc. The adduct which is a reactant with a containing compound, etc. are mentioned.

In this invention, this isocyanate type crosslinking agent (C) may be used individually by 1 type, and may be used in combination of 2 or more type. Moreover, it is preferable that the usage-amount is the range of 2-30 mass parts as a polyisocyanate compound with respect to 100 mass parts of said 2nd (meth) acrylic acid ester polymers (B) [triblock copolymer]. If this amount is less than 2 parts by mass, the thermal crosslinking of the triblock copolymer becomes insufficient, and an adhesive composition having a desired performance is not obtained. On the other hand, if it exceeds 30 parts by mass, the pot life is shortened. Stable coating becomes difficult. From this point of view, the amount of the isocyanate-based crosslinking agent (C) used is preferably 5 to 20 parts by mass, more preferably 7 to 100 parts by mass of the polymer (B) as a polyisocyanate compound. To 15 parts by mass. Moreover, as mentioned above, the site | part which becomes a crosslinking point of a crosslinking agent (C) with respect to 100 mol of hydroxyl groups in a polymer (B) is 100 mol or less from a viewpoint of reacting only a hydroxyl group of a polymer (B). It is preferable to become it, and it is especially preferable to become 80 mol or less. Moreover, it is preferable that the site | part used as the crosslinking point of a crosslinking agent (C) is 30 mol or more with respect to 100 mol of hydroxyl groups in a polymer (B) from a viewpoint of obtaining sufficient cohesion force with a crosslinked structure with a polymer (B), and is 40 mol or more It is more preferable, and it is especially preferable that it is 50 mol or more.

(Silane-based coupling agent)

The pressure-sensitive adhesive composition of the present invention can further contain a silane coupling agent. This silane coupling agent is used, for example, to adhere an optical member such as a polarizing plate to a liquid crystal cell glass substrate with good adhesion even under moist heat conditions via the pressure-sensitive adhesive of the present invention.

Examples of the silane coupling agent include triethoxysilane, vinyl tris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane and γ-glycidoxypropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethyldi Methoxysilane, (gamma) -aminopropyl triethoxysilane, N-phenyl (gamma) -aminopropyl trimethoxysilane, (gamma)-mercaptopropyl trimethoxysilane, (gamma)-chloropropyl trimethoxysilane, etc. are mentioned.

Moreover, 3-isocyanatopropyl triethoxysilane, 3-isocyanatopropyl (methyl) diethoxysilane, 2-isocyanato ethyl triethoxysilane, 2-isocyanatoethyl (methyl) ) Diethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyl (methyl) diethoxysilane, 2-glycidoxyethyltriethoxysilane, 2-glycidoxyethyl (methyl ) Diethoxysilane, 3- (3,4-epoxycyclohexyl) propyltriethoxysilane, 3- (3,4-epoxycyclohexyl) propyl (methyl) diethoxysilane, 2- (3,4- Epoxycyclohexyl) ethyl triethoxysilane, 2- (3,4-epoxycyclohexyl) ethyl (methyl) diethoxysilane, and the silane compound which substituted the ethoxy group of these silane compounds with a methoxy group can also be used. .

These silane coupling agents may be used individually by 1 type, and may be used in combination of 2 or more type. Moreover, the addition amount is about 0.001-10 mass parts normally with respect to 100 mass parts of solid content of the adhesive composition of this invention, Preferably it is 0.1-7 mass parts.

(Preparation of Coating Liquid Containing Adhesive Composition)

There is no restriction | limiting in particular in the preparation method of the coating liquid containing the adhesive composition of this invention, For example, the above-mentioned 1st (meth) acrylic acid ester polymer (A) and 2nd (meth) acrylic acid ester polymer (B) [triblock copolymer], an isocyanate-based crosslinking agent (C) and a silane coupling agent used as necessary, and various additives such as antioxidants, ultraviolet absorbers, light stabilizers, leveling agents, The coating liquid containing the adhesive composition of this invention can be prepared by adding an antistatic agent, a refractive index regulator, a flame retardant, an antifoamer, etc., and stirring and mixing.

Examples of the solvent include aliphatic hydrocarbons such as hexane and heptane, aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as methylene chloride and ethylene, alcohols such as methanol, ethanol, propanol and butanol, acetone and methylethyl. Ketones such as ketones, 2-pentanone, isophorone and cyclohexanone, esters such as ethyl acetate and butyl acetate, cellosolve solvents such as ethyl cellosolve, and glycols such as propylene glycol monomethyl ether And ether solvents. These solvent may be used individually by 1 type, and may mix and use 2 or more types.

As solid content concentration in this coating liquid, the coating liquid should just be a viscosity suitable for coating, and there is no restriction | limiting in particular.

Next, the adhesive of this invention is demonstrated.

[adhesive]

The adhesive of this invention is obtained by heat-crosslinking the adhesive composition obtained using the coating liquid containing the adhesive composition obtained as mentioned above.

Thermal crosslinking applies the coating liquid containing the said adhesive composition on a peeling sheet by the method of mentioning later, for example, it is made to dry at 60-110 degreeC, about 1 to 10 minutes, after that, 23-30 degreeC, It can be completed by taking a curing period of about 1 to 2 weeks.

The adhesive of this invention needs that a gel fraction is 40% or more. When this gel fraction is less than 40%, durability under high temperature and high humidity is bad, and it is also insufficient in a heat shock test. Moreover, from a viewpoint of rework property and durability, this gel fraction becomes like this. Preferably it is 40 to 85%, More preferably, it is 40 to 70%.

In addition, the said gel fraction is the value measured by the following method.

<Measurement of gel fraction>

Only the adhesive is taken out and weighed, and the weight at this time is referred to as M1. This was added to ethyl acetate and refluxed for 16 hours or more using a Soxhlet extractor, followed by taking out only the insolubles, drying off the solvent contained in the insolubles, and weighing it. . The gel fraction is expressed as (M 2 / M 1) × 100 (%).

(Adhesive sheet)

On the peeling layer of a peeling sheet, the coating liquid containing the adhesive composition mentioned above is used, for example using the bar coat method, the knife coat method, the roll coat method, the blade coat method, the die coat method, the gravure coat method, etc. Coating, heat-drying, heat crosslinking are carried out, and an adhesive layer is formed. Next, by attaching another peeling sheet different in peeling strength from the said peeling sheet so that the peeling layer may contact on this adhesive layer, it can be set as the adhesive sheet which inserted an adhesive layer between two peeling sheets. Can be.

Moreover, the thickness (not peeling sheet) of this adhesive sheet is about 5-100 micrometers normally, Preferably it is 10-50 micrometers.

Examples of the release sheet include plastic films such as polyethylene terephthalate (hereinafter sometimes referred to as "PET"), polyester films such as polybutylene terephthalate and polyethylene naphthalate, and polyolefin films such as polypropylene and polyethylene, The thing which apply | coated peeling agents, such as a silicone resin, and formed the peeling layer is mentioned. Although there is no restriction | limiting in particular about the thickness of this peeling sheet, Usually, it is about 20-150 micrometers.

Next, the optical member with an adhesive layer of this invention is demonstrated.

[Optical member with adhesive layer]

This invention also provides the optical member with an adhesive layer which has the layer which consists of the adhesive of this invention mentioned above on an optical member.

As said optical member, a polarizing plate, a retardation plate, an optical compensation film, a reflection sheet, a brightness enhancement film, etc. are mentioned, for example, Among these, a polarizing plate and a retardation plate are used preferably. Moreover, the thickness of the adhesive layer which consists of an adhesive of this invention is about 5-100 micrometers normally, Preferably it is 10-50 micrometers, More preferably, it is 10-30 micrometers.

This optical member with an adhesive layer can be produced as follows, for example.

On the peeling layer of a peeling sheet, according to the above-mentioned method, an adhesive composition layer is formed, heated and dried, it is thermally crosslinked, and after forming an adhesive layer, the optical member with an adhesive layer is stuck by attaching an optical member thereon. Can be produced.

Although the adhesive of this invention is applied to the polarizing plate which consists of a polarizing film alone, it can be used to adhere this polarizing plate, for example to a liquid crystal glass cell, but it applies especially to the polarizing plate in which a polarizing film and a viewing angle expansion film are integrated, This polarizing plate can be preferably used, for example, for adhering to a liquid crystal glass cell.

As a polarizing plate in which the said polarizing film and the viewing angle expansion film are integrated, for example, it is a disco, for example, on the one side of the polarizing film formed by attaching a triacetyl cellulose (TAC) film to both surfaces of a polyvinyl alcohol-type polarizer, respectively. The thing formed by the application | coating of the viewing angle expansion function layer which consists of tick liquid crystals, or the pasting of the viewing angle expansion film with an adhesive agent, etc. are mentioned. In this case, the adhesive of this invention is provided in the said viewing angle expansion layer or the viewing angle expansion film side.

The liquid crystal display device produced by adhering the polarizing plate to the liquid crystal glass cell as described above using the pressure-sensitive adhesive of the present invention is less likely to cause light leakage even in a high temperature and high humidity environment, and also has excellent adhesion durability between the polarizing plate and the liquid crystal glass cell. This is excellent.

Moreover, in order to improve the viewing angle characteristic, the adhesive of this invention can be used suitably also when a phase difference plate is arrange | positioned through an adhesive between a polarizing plate and a liquid crystal cell. That is, what is necessary is just to stick the polarizing plate and retardation plate which consist of a polarizing film alone with the adhesive of this invention, to manufacture an optical film, and to stick the retardation plate and liquid crystal glass cell of this optical film with an adhesive. It does not specifically limit as an adhesive which sticks a retardation plate and a liquid crystal glass cell here, Usually, the adhesive used for bonding of a polarizing plate and a liquid crystal glass cell can be used.

[ Example ]

Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.

In addition, the various characteristics of the adhesive were calculated | required according to the following method.

<Processing method>

The thickness of the adhesive layer after drying the coating liquid containing the adhesive composition prepared so that it may become the compounding composition shown in Table 1 on the release sheet [Rintech Co., Ltd. product, "SP-PET382050" made of PET with a thickness of 38 micrometers is 25 It was apply | coated with the knife-type coating machine so that it might become micrometer. The drying temperature was 90 ° C. and the drying time was 1 minute.

Then, the polarizing film with a discotic liquid crystal layer was stuck so that the said adhesive layer and the discotic liquid crystal layer might contact. After attaching, the curing plate for 1 week was taken at 23 degreeC and 50% Rh, and the polarizing plate with an adhesive layer was obtained.

<Adhesive force>

The polarizing plate with the pressure-sensitive adhesive layer was sampled at a length of 25 mm width x 100 mm, the peeling film was peeled off, and it was stuck to an alkali free glass ("Eagle XG" manufactured by Corning Corporation) (that is, affixed). After affixing, it pressurized on the "autoclave" (Kurihara Seisakusho Co., Ltd.) on the conditions of 0.5 Mpa, 50 degreeC, and 20 minutes.

Then, it was left to stand on 23 degreeC and 50% Rh environment for 24 hours, and the adhesive force was measured on condition of the following using "Tenshiron" (Orientech company make).

Peeling rate: 300 mm / min, Peeling angle: 180 ° C.

In addition, the standing conditions (24 hours under 23 ° C. and 50% Rh environment) before measuring the adhesive force were changed to 14 days under 23 ° C. and 50% Rh environment and 2 days under 50 ° C. and 50% Rh environment, respectively. It carried out together with the measurement of adhesive force.

Durability Assessment

The polarizing plate with the pressure-sensitive adhesive layer was adjusted to a size of 233 mm x 309 mm using a super cutter (manufactured by Ogino Seisakusho Co., Ltd.). And after peeling a peeling sheet and sticking the exposed adhesive layer to alkali-free glass [The Corning company make, "Eagle XG"], it is 0.5 Mpa, 50 degreeC, 20 minutes to "autoclave" (Kurihara Seisakyu Sho) make. Pressurized on condition of. Thereafter, charging was performed under each of the durable conditions, followed by observation using a 10-fold magnifier after 200 hours. The appearance change was based on the following criteria.

(Circle): There is no defect in 0.6 mm or more of outer peripheral edges in four sides.

(Triangle | delta): Any one of four sides has a faulty external appearance of the adhesive of 0.5 mm or less, such as lifting, peeling, foaming, and a stripe, 0.6 mm or more from an outer periphery on one side.

X: Any one of four sides has a fault more than the external appearance of the adhesive of 0.6 mm or more, such as lifting, peeling, foaming, and a stripe, 0.6 mm or more from an outer periphery on one side.

Durability

60 ℃, 90% Rh environment

80 ℃, dry environment

HS: 200 cycles of heat shock tester for 30 minutes each -35 degreeC 70 degreeC

<Light leakage prevention>

The polarizing plate with the pressure-sensitive adhesive layer was adjusted to a size of 233 mm x 309 mm using a super cutter (manufactured by Ogino Seisakusho Co., Ltd.). And after peeling a peeling sheet and sticking the exposed adhesive layer to alkali-free glass [The Corning company make, "Eagle XG"], it is 0.5 Mpa, 50 degreeC, 20 minutes to "autoclave" (Kurihara Seisakyu Sho) make. Pressurized on condition of. When pasting, the said polarizing plate with an adhesive layer which peeled off the peeling sheet was stuck to the front and back of glass so that a polarizing axis might be in a cross nicol state. The light leakage prevention property was evaluated by the method shown below after 200 hours standing in 80 degreeC and a dry environment in this state. The brightness of each area shown in Fig. 1 was measured using "MCPD" (manufactured by Otsuka Denshi Co., Ltd.), and the brightness difference: ΔL * was expressed by the following equation:

ΔL ＊ = [(B + C + D + E) / 4] -A

(Where A, B, C, D and E are lightness at predetermined measurement points (one center part of each region) of A, B, C, D and E regions, respectively. It is to prevent leakage. In addition, it described as the maximum brightness as L * max.

In addition, light leakage prevention property was evaluated by the following criteria.

◎: ΔL * ≤ 1.0

△: 1.0 ≪ L * ≤ 2.0

×: ΔL *> 2.0

<Gel fraction>

The gel fraction was measured according to the method described in the text of the specification.

<Haze value>

The haze value of the 25-micrometer-thick adhesive layer was measured by the method shown below.

In the manufacturing process of the said polarizing plate with an adhesive layer described in the said processing method WHEREIN: A peeling sheet / adhesive agent is stuck by sticking another peeling sheet [The product made by Lintec, "SP-PET381130"] instead of the polarizing film with a discotic liquid crystal layer. The structure of the layer / peel sheet was produced. And the curing period of the same conditions as the case of the said polarizing plate with an adhesive layer was taken. After that, the peeling sheet [Lintech Co., Ltd. product, "SP-PET381130") of the said structure was peeled off, and the exposed adhesive layer surface was attached to soda-lime glass (made by Nippon Glass), and soda-lime glass / adhesive / peeling A film was produced. Thereafter, another peeling sheet (Lintech Co., Ltd. product, "SP-PET382050") was peeled off, and the haze value was adjusted according to JIS K 7136 using a haze meter ("NDH-2000" from Nippon Denshoku Co., Ltd.). Measured. When using as an adhesive for polarizing plates, a smaller haze value is preferable.

Example  1 to 10 and Comparative example  1 to 5

(1) Preparation of Acrylic Acid Ester Copolymer (A)

Using butyl acrylate (BA) and acrylic acid (AA) in the ratio (mass ratio) shown in Table 1, copolymerization was carried out according to the conventional method, and a butyl acrylate / acrylic acid random copolymer having a weight average molecular weight (Mw) shown in Table 1 was produced. It was.

(2) Preparation of Acrylic Acid Ester Copolymer (B)

(A) Preparation of Triblock Copolymer by Living Radical Polymerization

In Examples 1 to 10 and Comparative Examples 4 and 5, butyl acrylate and 2-hydroxyethyl acrylate (HEA) or 4-hydroxybutyl acrylate (4HBA) were used as living radical polymerization initiators as follows. The weight average molecular weight shown in Table 1 using the synthesized organic tellurium compound (ethyl-2-methyl-2-n-butyl teranyl propionate) and 2,2'- azobisisobutyronitrile Triblock copolymers of the type shown in Table 1 were also prepared having (Mw) and molecular weight distribution (PDI).

<Synthesis of ethyl-2-methyl-2-n-butylteranyl-propionate>

6.38 g (50 mmol) of metal tellurium (manufactured by Aldrich, product name: Tellurium (-40 mesh)) is suspended in 50 ml of tetrahytrofuran (THF), and n-butyllithium (manufactured by Aldrich) , 1.6 mol / L hexane solution] 34.4 ml (55 mmol) was slowly added dropwise at room temperature. The reaction solution was stirred until the metal tellurium was completely gone. 10.7 g (55 mmol) of ethyl-2-bromoisobutyrate was added to this reaction solution at room temperature, and it stirred for 2 hours. After the completion of the reaction, the solvent was concentrated under reduced pressure, followed by distillation under reduced pressure to obtain 8.98 g (yield 59.5%) of ethyl-2-methyl-2-n-butylteranyl-propionate as a yellow oil.

(B) Comparative Example 2 is a homopolymer of butyl acrylate by the free radical polymerization method, Comparative Example 3 is a random copolymer of butyl acrylate and lauryl acrylate by the living radical polymerization method, Comparative Example 1 is an acrylic ester copolymer ( In A) only, the acrylic ester copolymer (B) is not used.

(3) Preparation of pressure-sensitive adhesive composition

The pressure-sensitive adhesive composition of the formulation composition (solid content conversion) shown in Table 1 was prepared, the polarizing plate with the pressure-sensitive adhesive layer was prepared in accordance with the above-described processing method, and various properties of the pressure-sensitive adhesive were evaluated by the above-described method, and the gel fraction of the pressure-sensitive adhesive was measured. Obtained. The results are shown in Table 2.

As can be seen from Table 2, the pressure-sensitive adhesives (Examples 1 to 10) of the present invention are all more than "Δ" in the evaluation of durability and light leakage prevention property, but the pressure-sensitive adhesives of Comparative Examples 1 to 5 are all in the above evaluation. It has at least one "x".

The adhesive composition of this invention can be used suitably for the polarizing plate etc. which comprise a liquid crystal display device, and can form the adhesive layer which can prevent generation | occurrence | production of the white stripe phenomenon resulting from expansion and contraction of a polarizing plate.

Claims (9)

First (meth) acrylic acid ester polymer (A) having a weight average molecular weight of 1 to 2.5 million, Second (meth) acrylic acid ester polymer (B) having a weight average molecular weight of 20,000 to 150,000, and isocyanate As an adhesive composition containing system type crosslinking agent (C),
(1) the second (meth) acrylic acid ester polymer (B) is a triblock copolymer having a hydroxyl group-containing (meth) acrylate monomer unit;
(2) Content of said 2nd (meth) acrylic acid ester polymer (B) is less than 40 mass parts with respect to 100 mass parts of said 1st (meth) acrylic acid ester polymers (A); And
(3) The gel fraction of the pressure-sensitive adhesive formed of the pressure-sensitive adhesive composition is 40% or more
Acrylic pressure-sensitive adhesive composition, characterized in that. The triblock copolymer according to claim 1, wherein the triblock copolymer has a form of b2-b1-b2 or b1-b2-b1, wherein b1 is a (meth) acrylate monomer unit having no functional group serving as a crosslinking point. An acrylic pressure-sensitive adhesive composition wherein a block formed of the same, b2 represents a block made of a hydroxyl group-containing (meth) acrylate monomer unit. The acrylic pressure sensitive adhesive composition according to claim 1, wherein the ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the triblock copolymer is 1.0 to 1.8. The acrylic pressure-sensitive adhesive composition of claim 2, wherein the ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the triblock copolymer is 1.0 to 1.8. The content of the hydroxyl group-containing (meth) acrylate monomer unit in the triblock copolymer is 1.5 to 20% by mass, and the content of the triblock copolymer according to any one of claims 1 to 4 It is 10-30 mass parts with respect to 100 mass parts of (meth) acrylic acid ester polymers (A) of 1, The acrylic adhesive composition. The acrylic adhesive composition according to any one of claims 1 to 4, wherein the triblock copolymer is formed by living radical polymerization. The content of the isocyanate-based crosslinking agent (C) is 5 to 20 parts by mass based on 100 parts by mass of the second (meth) acrylic acid ester polymer (B). Acrylic pressure-sensitive adhesive composition. An acrylic pressure sensitive adhesive formed by heat crosslinking the acrylic pressure sensitive adhesive composition according to any one of claims 1 to 4. The optical member with an adhesive layer formed by laminating | stacking the acrylic adhesive of Claim 8 in layer shape on an optical member.

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