KR20130002264A - Adhesive and adhesive sheet - Google Patents

Abstract

PURPOSE: An adhesive and an adhesive sheet are provided to have antistatic performance, and to have excellent stress-releasing performance and durability when applied to an optical unit such as a polarizer. CONSTITUTION: An adhesive comprises: a component which is obtained by crosslinking a first (meth)acrylic acid ester with the weight average molecular weight of 500,000-3,000,000, a second (meth)acrylic ester polymer with the average molecular weight of 8,000-300,000; and an antistatic agent. The adhesive has a braking elongation of 1500% or more by a tensile stress test, and a gel fraction of 30-90%. The ratio of the second (meth)acrylic ester polymer to 100 parts by weight of the acrylic ester polymer is 5-50 parts by weight. An adhesive sheet(1A) comprises a substrate(13) and an adhesive layer(11) which consists of the adhesive.

Description

Adhesive and adhesive sheet {ADHESIVE AND ADHESIVE SHEET}

The present invention relates to an adhesive and an adhesive sheet, and in particular, to an adhesive and an adhesive sheet suitable for an optical member such as a polarizing plate.

In general, in a liquid crystal panel, an adhesive layer formed of an adhesive composition is often used to adhere a polarizing plate or a retardation plate to a glass substrate of a liquid crystal cell. However, since optical members such as polarizing plates and retardation plates tend to shrink due to heat and the like, shrinkage occurs due to thermal history, and as a result, the pressure-sensitive adhesive layer laminated on the optical member cannot follow the shrinkage. It has been pointed out that a problem arises in that peeling (so-called lifting, peeling) occurs or light leakage (so-called white hair) caused by the optical axis of the optical member is deviated due to the stress at the time of shrinkage of the optical member.

As a method for preventing this, (1) a method of suppressing shrinkage of the optical member itself by bonding an adhesive layer having a high adhesion and excellent shape stability to an optical member such as a polarizing plate, or (2) shrinking of the optical member The method of using the adhesive layer with small stress at the time is mentioned. As the method of (1), it is effective to use the adhesive layer with high storage elastic modulus, as published in patent document 1. On the other hand, it is effective to use the adhesive layer excellent in the stress relaxation property which can respond flexibly to the deformation | transformation of an optical member as the method of (2). However, conventionally, when it was decided to form an adhesive layer excellent in such a stress relaxation property, it was necessary to design low the crosslinking density in the adhesive layer. As a result, the strength of the pressure-sensitive adhesive layer itself is lowered, and there is a problem that durability deteriorates.

Therefore, in Patent Documents 2 to 4, instead of lowering the crosslinking density of the pressure-sensitive adhesive layer, by adding a plasticizer, a liquid paraffin, a urethane elastomer and the like to the acrylic pressure-sensitive adhesive, the resulting pressure-sensitive adhesive composition is moderately softened to impart stress relaxation to the pressure-sensitive adhesive layer. By doing so, it tries to obtain light leakage resistance and durability.

However, the adhesive composition which added the plasticizer or the liquid paraffin had the difficulty of bridging out the plasticizer and the liquid paraffin with time as the adhesive layer formed over time. Thereby, various problems, such as adhesive durability fall, the liquid crystal cell used as a to-be-adhered body become contaminated by this, are concerned. Moreover, since the upper limit of the addition amount of a urethane elastomer is restrict | limited to the adhesive composition which added the urethane elastomer, when maintaining compatibility, there existed a tendency for the improvement of stress relaxation property to become inadequate. Furthermore, when the addition amount of urethane elastomer was increased in order to improve stress relaxation property, compatibility with an acrylic adhesive fell, and the problem, such as cloudiness, occurred. As described above, in the prior art, it was difficult to fundamentally improve the light leakage resistance and durability of the pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition for optical members.

By the way, the optical member, such as the peeling sheet in which the said adhesive layer is laminated | stacked, or a polarizing plate and a retardation plate, is comprised normally with a plastic material. Therefore, electrical insulation is high, and static electricity is easy to generate | occur | produce when peeling a peeling sheet. When a polarizing plate, a retardation plate, or the like is bonded to the liquid crystal cell in the state in which the generated static electricity remains, scattering may occur in the alignment of the liquid crystal molecules, and the presence of the static electricity may cause problems such as sucking dust and garbage. Causes

Here, in order to acquire an effective antistatic performance, adding an antistatic agent to an adhesive composition is proposed (for example, patent documents 5-8).

[Patent Document 1] Japanese Patent Laid-Open No. 2006-235568 [Patent Document 2] Japanese Patent Application Laid-Open No. 5-45517 [Patent Document 3] Publication No. 9-137143 [Patent Document 4] Japanese Patent Application Laid-Open No. 2005-194366 [Patent Document 5] Japanese Patent Application Laid-Open No. 2005-194366 [Patent Document 6] Japanese Patent Application Laid-Open No. 2007-316377 [Patent Document 7] Japanese Patent Application Laid-Open No. 2008-95081 [Patent Document 8] Japanese Patent Application Laid-Open No. 2009-155585

However, when an antistatic agent is added to an adhesive composition, there exists a problem that durability of the adhesive obtained is lowered than usual. In this pressure-sensitive adhesive, lowering the crosslinking density or adding a plasticizer or the like in order to impart stress relaxation properties further lowers durability as described above. Therefore, it is more difficult to impart stress relaxation. As described above, even in the pressure-sensitive adhesive having antistatic properties, both of the stress relaxation and the durability in the relation of contradiction were problems.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an adhesive and an adhesive sheet having antistatic properties and excellent in both stress relaxation and durability when applied to an optical member such as a polarizing plate.

In order to achieve the above object, firstly, the present invention provides a first (meth) acrylic acid ester polymer (A) having a weight average molecular weight of 500,000 to 3 million, and a second (meth) acrylic acid ester having a weight average molecular weight of 8,000 to 300,000. A pressure-sensitive adhesive comprising a component formed by crosslinking a polymer (B), an antistatic agent (C), an elongation at break by a tensile test of 1500% or more, and a gel fraction of 30 to 90% is provided. One).

The pressure-sensitive adhesive according to the invention (Invention 1) exhibits appropriate cohesion and excellent stress relaxation while having antistatic properties. By using this pressure-sensitive adhesive having excellent stress relaxation property, when applied to an optical member such as a polarizing plate, a pressure-sensitive adhesive sheet excellent in both light leakage and durability can be obtained while exhibiting sufficient antistatic properties.

In the said invention (invention 1), it is preferable that the ratio of the said 2nd (meth) acrylic acid ester polymer (B) with respect to 100 mass parts of said 1st (meth) acrylic acid ester polymers (A) is 5-50 mass parts. (Invention 2).

In the invention (Invention 1, 2), the first (meth) acrylic acid ester polymer (A) or the first (meth) acrylic acid ester polymer (A) and the second (meth) acrylic acid ester polymer before crosslinking ( It is preferable that B) contains 5-50 mass% of oxyalkylene group containing monomers as a monomer unit which comprises the said polymer (invention 3).

In the said invention (Invention 1-3), it is preferable that the said antistatic agent (C) is an ionic compound (invention 4).

In the invention (Invention 4), the ionic compound is preferably at least one selected from the group consisting of nitrogen onium salts, sulfur-containing onium salts, onium salts and alkali metal salts (invention 5).

In the said invention (invention 1-5), it is preferable that the said 2nd (meth) acrylic acid ester polymer (B) before crosslinking contains more than 1 mass% and less than 50 mass% of reactive functional group containing monomer as a structural component. (Invention 6)

In the said invention (invention 6), it is preferable that the said 2nd (meth) acrylic acid ester polymer (B) is bridge | crosslinked by reaction with the crosslinking agent (D) which has a crosslinkable group which can react with the said reactive functional group (invention 7). ).

Secondly, the present invention provides a pressure-sensitive adhesive sheet comprising a base material and a pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive layer comprises the pressure-sensitive adhesives (Inventions 1 to 7) (Invention 8).

In the said invention (invention 8), it is preferable that the said base material is an optical member (invention 9).

Thirdly, the present invention is a pressure-sensitive adhesive sheet having two release sheets and a pressure-sensitive adhesive layer sandwiched on the release sheet so as to contact the release surfaces of the two release sheets, wherein the pressure-sensitive adhesive layer comprises the pressure-sensitive adhesive (Inventions 1 to 7). An adhesive sheet comprising a) is provided (invention 10).

In the pressure-sensitive adhesive according to the present invention, by forming a three-dimensional network structure by a chemical crosslinked structure from a low-molecular weight polymer that has conventionally been used plastically, by inserting a plurality of high molecular weight polymer into the three-dimensional network structure, It is estimated that polymers of molecular weight are constrained to form pseudo-crosslinked structures between polymers of high molecular weight. Therefore, the pressure-sensitive adhesive has antistatic properties, has a high breaking elongation, and has a predetermined gel fraction, thereby exhibiting appropriate cohesion force and excellent stress relaxation property. By using this adhesive which has the outstanding stress relaxation property, when applying to optical members, such as a polarizing plate, while providing sufficient antistatic property, the adhesive sheet which is excellent in both light leakage and durability is obtained.

1 is a cross-sectional view of an adhesive sheet according to a first embodiment of the present invention.
2 is a cross-sectional view of an adhesive sheet according to a second embodiment of the present invention.
The figure which shows the measurement area | region of the light leakage test in the polarizing plate with an adhesive layer.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described.

〔adhesive〕

The pressure-sensitive adhesive according to the present embodiment has a weight average molecular weight of 500,000 to 3 million first (meth) acrylic acid ester polymer (A), and a weight average molecular weight of 8000 to 300,000 second (meth) acrylic acid ester polymer (B). A component formed by crosslinking and an antistatic agent (C) are contained. In addition, in this specification, a (meth) acrylic acid ester means both acrylic acid ester and methacrylic acid ester. Other similar terms are also the same. In addition, the "polymer" shall also include the concept of a "copolymer."

In the adhesive according to the present embodiment, the second (meth) acrylic acid ester polymer (B) (low molecular weight polymer) is crosslinked to form a three-dimensional network structure, and the first (meth) acrylic acid ester polymer (A (High-molecular-weight polymer) Two or more molecules are inserted with no direct chemical bonds or with very few chemical bonds, and the polymers (A) are constrained in a certain degree of freedom. It is estimated that the crosslinked structure is formed (the structure thus estimated may be referred to as "structure X" below). The pressure-sensitive adhesive having such a structure X has antistatic properties, high elongation at break and a predetermined gel fraction, thereby exhibiting appropriate cohesion force and excellent stress relaxation property. When the pressure-sensitive adhesive having such excellent stress relaxation property is applied to optical members such as polarizing plates, the pressure-sensitive adhesive is excellent in light leakage resistance and also excellent in durability, and can prevent lifting or peeling even under high temperature conditions.

Said adhesive, Preferably the weight average molecular weights 500,000-3 million 1st (meth) acrylic acid ester polymer (A), The weight average molecular weights 8000-300,000 2nd (meth) acrylic acid ester polymer (B) , An adhesive composition containing an antistatic agent (C) and a crosslinking agent (D), and particularly preferably, can be obtained by crosslinking an adhesive composition containing a silane coupling agent (E). Hereinafter, the said adhesive composition is demonstrated.

The (meth) acrylic acid ester polymer (A) or (B) includes a (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms of an alkyl group, a monomer (oxyalkylene group-containing monomer) having an alkylene oxide moiety, a crosslinking agent ( The copolymer of the monomer (reactive functional group containing monomer) which has a functional group reacting with D), and the other monomer used as desired is preferable. On the other hand, it is also preferable that a 1st (meth) acrylic acid ester polymer (A) does not contain the said reactive functional group containing monomer as a structural unit. Moreover, it is also preferable that a 2nd (meth) acrylic acid ester polymer (B) does not contain the said oxyalkylene group containing monomer as a structural unit.

Examples of the (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, and (meth) acrylic acid. n-pentyl, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, n-decyl (meth) acrylate, n-dodecacrylate (meth) acrylate Thread, myristyl (meth) acrylate, palmityl (meth) acrylate, stearyl (meth) acrylate, etc. are mentioned. These may be used independently and may be used in combination of 2 or more type.

As for a 1st (meth) acrylic acid ester polymer (A), as a structural unit, it is preferable to contain 5-100 mass% of (meth) acrylic-acid alkylesters of 1-20 carbon atoms of an alkyl group, and especially 30-90 mass% contains It is preferable to, and it is preferable to contain 40-80 mass% further. Desired adhesiveness is obtained when content of the said (meth) acrylic-acid alkylester exists in the range of 5-100 mass%. Moreover, content of the said (meth) acrylic-acid alkylester exists in the range of 30-90 mass%, and content of the oxyalkylene group containing monomer and the reactive functional group containing monomer in a polymer (A) can be ensured.

Moreover, it is preferable that 2nd (meth) acrylic acid ester polymer (B) contains 5-99 mass% of (meth) acrylic-acid alkylesters of 1-20 carbon atoms of an alkyl group as a structural unit, Especially 30-90 mass It is preferable to contain%, and also it is preferable to contain 40-80 mass%. When content of the said (meth) acrylic-acid alkylester exists in the range of 5-99 mass%, desired adhesiveness is obtained and content of the reactive functional group containing monomer in a polymer (B) can be ensured. Moreover, content of the said (meth) acrylic-acid alkylester exists in the range of 30-90 mass%, and content of the oxyalkylene group containing monomer in a polymer (B) can also be ensured.

Examples of the oxyalkylene group-containing monomers include 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2-methoxypropyl (meth) acrylate, and 3-methoxypropyl (meth) acrylate. (Meth) acrylic acid alkoxy esters, such as 2-methoxybutyl (meth) acrylate and 4-methoxybutyl (meth) acrylate, are mentioned preferably. Furthermore, the (meth) acrylic-acid alkoxy ester which has polyalkylene glycol chains, such as the polyethylene glycol chain of a terminal alkoxy group, or a polypropylene glycol chain, is also mentioned preferably. Among them, (meth) acrylic acid 2-methoxyethyl is particularly preferable in view of excellent compatibility with each monomer during polymerization for obtaining the polymer (A) or (B). These may be used independently and may be used in combination of 2 or more type.

An oxyalkylene group containing monomer is contained only as a structural unit in a 1st (meth) acrylic acid ester polymer (A) or a 1st (meth) acrylic acid ester polymer (A) and a 2nd (meth) acrylic acid ester polymer (B). It is preferable. Thus, when the 1st (meth) acrylic acid ester polymer (A) contains an oxyalkylene group containing monomer as a structural unit, the antistatic performance by antistatic agent (D) improves by the alkoxy site | part which shows hydrophilicity. Therefore, content of the antistatic agent (D) in the adhesive composition which concerns on this embodiment can be made small. On the other hand, when only the 2nd (meth) acrylic acid ester polymer (B) has an oxyalkylene group containing monomer as a structural unit, in the process of forming the three-dimensional network structure by the said polymer (B) and a crosslinking agent (D), the said three-dimensional network It is assumed that the polarity difference between the structural portion and the polymer (A) is increased. Therefore, there exists a possibility that the optical characteristic may fall by the phase separation of both components, or the said structure X may not be fully formed. Therefore, it is preferable to avoid the said form.

As for a 1st (meth) acrylic acid ester polymer (A), as a structural unit, it is preferable to contain 5-50 mass% of said oxyalkylene group containing monomers, It is preferable to contain 10-40 mass% especially, Furthermore, 15 It is preferable to contain -35 mass%. The same applies when the second (meth) acrylic acid ester polymer (B) contains an oxyalkylene group-containing monomer as a structural unit. When the content of the oxyalkylene group-containing monomer is in the above range, the excellent effect described above can be obtained, and the content of the (meth) acrylic acid alkyl ester and the reactive functional group-containing monomer in the adhesive composition according to the present embodiment can be ensured. .

On the other hand, as a reactive functional group containing monomer, the monomer (hydroxyl group containing monomer) which has a hydroxyl group in a molecule | numerator, the monomer (carboxyl group containing monomer) which has a carboxyl group in a molecule | numerator, the monomer (amino group containing monomer) etc. which have an amino group in a molecule | numerator are mentioned preferably, etc. . In addition, as a reactive functional group (a1) containing monomer mentioned later, a reactive functional group (b1) containing monomer, and the reactive functional group (b2) containing monomer, the reactive functional group containing monomer described here corresponds. Selection of the kind is as having demonstrated in the item of each monomer.

As a hydroxyl-containing monomer, For example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, (Meth) acrylic-acid hydroxy alkyl esters, such as 3-hydroxy butyl (meth) acrylic acid and 4-hydroxy butyl (meth) acrylic acid, etc. are mentioned. These may be used independently and may be used in combination of 2 or more type.

As a carboxyl group-containing monomer, ethylenic unsaturated carboxylic acids, such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, a citraconic acid, are mentioned, for example. These may be used independently and may be used in combination of 2 or more type.

As an amino group containing monomer, (meth) acrylic-acid amino ethyl, (meth) acrylic-acid n-butylamino ethyl, etc. are mentioned, for example. These may be used independently and may be used in combination of 2 or more type.

Moreover, as said other monomer, the (meth) acrylic acid ester, acrylamide, which has aromatic rings, such as (meth) acrylic acid ester which has aliphatic rings, such as cyclohexyl (meth) acrylic acid, and phenyl (meth) acrylic acid, (Meth) which has non-crosslinkable tertiary amino groups, such as non-crosslinkable (meth) acryl amide, such as methacryl amide, N, N-dimethyl amino ethyl (meth) acrylic acid, and N, N-dimethyl amino propyl (meth) acrylate Acrylic ester, vinyl acetate, styrene, etc. are mentioned. These may be used independently and may be used in combination of 2 or more type.

The 2nd (meth) acrylic acid ester polymer (B) has a monomer (reactive functional group (b1) containing monomer) which has a functional group (b1) which reacts with a crosslinking agent (C) as a component. It is preferable that the functional group which reacts with a crosslinking agent (C) which the said polymer (B) contains is substantially only a functional group (b1). On the other hand, "substantially only functional group (b1)" allows to include another functional group which reacts with a crosslinking agent (C) to such an extent that does not prevent the reactivity of functional group (b1) and a crosslinking agent (C).

That is, the second (meth) acrylic acid ester polymer (B) is a constituent component of a monomer having a functional group (b2) having a lower reactivity with the crosslinking agent (C) than the functional group (b1) (a monomer containing a reactive functional group (b2)). It is preferable not to contain it. However, in the case of containing the reactive functional group (b2) -containing monomer as a constituent component, it is preferable to contain an amount of 1/5 or less, especially 1/10 or less, of the content of the reactive functional group (b1) -containing monomer as a mass ratio. .

In addition, the reactive functional group (b1) containing monomer and the reactive functional group (b2) containing monomer used for a 2nd (meth) acrylic acid ester polymer (B), and the reactivity used for the 1st (meth) acrylic acid ester polymer (A) mentioned later Selection of the functional group (a1) containing monomer is determined by the relationship with the reactivity with the crosslinking agent (C) to be used. Details will be described later.

Durability of the adhesive layer obtained when a 2nd (meth) acrylic acid ester polymer (B) contains a reactive functional group (b2) containing monomer in quantity exceeding 1/5 of content of a reactive functional group (b1) containing monomer as mass ratio. There is a fear that this is lowered. When there are too many reactive functional groups (b2) in a 2nd (meth) acrylic acid ester polymer (B), many reactive functional groups (b2) remain also in the three-dimensional network structure formed by this, and the said three-dimensional network structure and 1st It is presumed to cause a change in the compatibility of the (meth) acrylic acid ester polymer (A). As a result, the haze value may increase. Moreover, it is also estimated that the three-dimensional network structure in which the reactive functional group (b2) remains much excessively restricts the mobility of the 1st (meth) acrylic acid ester polymer (A) inserted in the said three-dimensional network structure. As a result, the breaking elongation of the obtained adhesive becomes small, and durability may worsen.

In addition, when the adhesive composition which concerns on this embodiment contains a silane coupling agent (E), a silane coupling agent (E) is a reactive functional group (a1) of the 1st (meth) acrylic acid ester polymer (A) mentioned later (especially Carboxyl group) to bind with a high molecular weight first (meth) acrylic acid ester polymer (A). In addition, the bond here is not limited to a covalent bond, It is a concept including hydrogen bond, hydrophobic interaction, Pander Baals force, etc. Thereby, since the alkoxysilyl group part of a silane coupling agent acts with a glass substrate, it is estimated that adhesiveness with the glass substrate which is a to-be-adhered body etc. is improved by the adhesive obtained. Here, when the 2nd (meth) acrylic acid ester polymer (B) contains the reactive functional group (b2) -containing monomer excessively, the alkoxy silyl group of a silane coupling agent (E), etc. will be a 2nd (meth) acrylic acid ester polymer ( It is estimated that it reacts with the reactive functional group (b2) (especially a carboxyl group) of B), couple | bonds with the low molecular weight 2nd (meth) acrylic acid ester polymer (B), and takes away the opportunity to combine with a to-be-adhered body. As a result, the adhesive obtained is inferior to adhesiveness with glass substrates etc. which are adherends, and there exists a possibility that durability of an adhesive layer may fall by this.

It is preferable that a 2nd (meth) acrylic acid ester polymer (B) contains the said reactive functional group (b1) containing monomer more than 1 mass% and less than 50 mass%. More preferably, 5-40 mass% of said reactive functional group (b1) containing monomers are contained, Especially preferably, it is 10-30 mass%, More preferably, it contains 12-20 mass%. By containing a reactive functional group (b1) containing monomer in the said range, the grade of the crosslinking of a 2nd (meth) acrylic acid ester polymer (B) becomes preferable, and is obtained by the combination of a 1st (meth) acrylic acid ester polymer (A) Elongation at break of the pressure-sensitive adhesive increases, and the pressure-sensitive adhesive tends to have a predetermined gel fraction. As a result, the pressure-sensitive adhesive is excellent in durability and stress relaxation properties. Moreover, when content of a reactive functional group (b1) containing monomer is 1 mass% or less, crosslinking of a 2nd (meth) acrylic acid ester polymer (B) may not be enough and a gel fraction may become below a predetermined value, and by this There exists a possibility that durability may fall. On the other hand, when content of a reactive functional group (b1) containing monomer is 50 mass% or more, crosslinking of a 2nd (meth) acrylic acid ester polymer (B) will become excessive and a breaking elongation may become small, and durability falls by this There is concern. On the other hand, by making the upper limit of content of a reactive functional group (b1) containing monomer into 30 mass%, it becomes more excellent in the light leakage resistance of the adhesive sheet obtained.

Here, the polymerization form of the 2nd (meth) acrylic-acid ester polymer (B) obtained by superposing | polymerizing the C1-C20 (meth) acrylic-acid alkylester of the alkyl group and the monomer which has a functional group reacting with a crosslinking agent (D), A random copolymer may be sufficient and a block copolymer may be sufficient.

In this embodiment, said 2nd (meth) acrylic-ester type polymer (B) may be used individually by 1 type, and may be used in combination of 2 or more type.

The weight average molecular weight of a 2nd (meth) acrylic acid ester polymer (B) is 8000-300,000, Preferably it is 10,000-200,000, Especially preferably, it is 50,000-100,000. In other words, the second (meth) acrylic acid ester polymer (B) is a low molecular weight polymer component. In addition, the weight average molecular weight in this specification is a polystyrene conversion value measured by the gel permeation chromatography (GPC) method.

When the weight average molecular weight of a 2nd (meth) acrylic acid ester polymer (B) exists in the said range, the three-dimensional network structure peculiar to the adhesive composition which concerns on this embodiment is formed, and contributes to the outstanding stress relaxation property. In other words, when the weight average molecular weight of the second (meth) acrylic acid ester polymer (B) is less than 8000, a good three-dimensional network structure cannot be obtained. On the other hand, when the weight average molecular weight of a 2nd (meth) acrylic acid ester polymer (B) exceeds 300,000, the compatibility of a 1st (meth) acrylic acid ester polymer (A) etc. will fall, and the haze value of an adhesive layer will rise, etc. The optical characteristic may be inferior. In addition, the insertion of the polymer (A) into the three-dimensional network structure formed by the polymer (B) becomes insufficient, and the gel fraction may fall below a predetermined range. As a result, the adhesive obtained may be inferior in durability and rework property.

The 1st (meth) acrylic acid ester polymer (A), Preferably, it does not contain the monomer which has a functional group which reacts with a crosslinking agent (D) as a component, or the said functional group of a 2nd (meth) acrylic acid ester polymer (B) A monomer (reactive functional group (a1) -containing monomer) having a functional group (a1) having a lower reactivity with the crosslinking agent (D) than (b1) is contained, and particularly preferably, it is a crosslinking agent (D) more than the functional group (b1). It does not contain as a component a monomer having a highly reactive functional group with).

The 1st (meth) acrylic acid ester polymer (A) does not need to contain the monomer which has a functional group which reacts with a crosslinking agent (D). However, when a reactive functional group (a1) containing monomer is included, it may be preferable. In other words, when the reactive functional group (a1) is contained in the polymer (A), it is expected to accelerate the reaction of the second (meth) acrylic acid ester polymer (B) and the crosslinking agent (D). Or when using a silane coupling agent (E), the reactive functional group (a1) of a 1st (meth) acrylic acid ester polymer (A) acts with the said silane coupling agent (E), such as the liquid crystal cell of the adhesive obtained Adhesive durability to a glass surface can be made more suitable, and it may be preferable.

When the 1st (meth) acrylic acid ester polymer (A) contains the said reactive functional group (a1) containing monomer, the content is 20 mass% or less normally, It is preferable that it is 15 mass% or less, It is especially 10 mass% or less desirable. When content of a reactive functional group (a1) containing monomer exceeds 20 mass%, there exists a possibility that the glass potential temperature (Tg) of a 1st (meth) acrylic acid ester polymer (A) may become high too much and the stress relaxation property of the adhesive obtained will fall. have. On the other hand, it is preferable to make content of the reactive functional group (a1) containing monomer into 15 mass% or less from a viewpoint of providing rework property to an adhesive.

In addition, in comparison with the reactive functional group (b1) containing monomer which a 2nd (meth) acrylic acid ester polymer (B) contains, the reactive functional group (a1) containing monomer which a 1st (meth) acrylic acid ester polymer (A) contains. The ratio in the said 1st (meth) acrylic acid ester polymer (A) of the said 2nd (meth) acrylic acid ester polymer of the reactive functional group (b1) containing monomer which a 2nd (meth) acrylic acid ester polymer (B) contains ( It is preferable that it is smaller than the ratio in B). Thereby, reaction of the reactive functional group (a1) and crosslinking agent (D) which a 1st (meth) acrylic acid ester polymer (A) contains, and the reactive functional group which a 2nd (meth) acrylic acid ester polymer (B) contains (b1) and a crosslinking agent (D) can be made to react reliably. Thereby, when extending | stretching, the adhesive at break of 1500% or more can be obtained suitably.

The first (meth) acrylic acid ester polymer (A) does not contain a monomer having a functional group equivalent to or more than the reactive functional group (b1) of the second (meth) acrylic acid ester polymer (B) having a reactivity with the crosslinking agent (D). It is preferable. However, if it contains, it is preferable that content of the monomer which has the said functional group in a molecule | numerator is 1 mass% or less in polymer (A), and it is especially preferable that it is 0.5 mass% or less. When content of the said monomer exceeds 1 mass%, there exists a possibility that it may inhibit reaction of the 2nd (meth) acrylic acid ester polymer (B) and crosslinking agent (D) which should react preferentially. As a result, the desired stress relaxation property may not be obtained.

Here, a random copolymer may be sufficient as the superposition | polymerization form of the (meth) acrylic-acid alkylester of 1-20 carbon atoms of an alkyl group, and the 1st (meth) acrylic-acid ester polymer (A) obtained by superposing | polymerizing a reactive functional group containing monomer, and a block A copolymer may be sufficient.

In this embodiment, said 1st (meth) acrylic acid ester polymer (A) may be used individually by 1 type, and may be used in combination of 2 or more type.

The weight average molecular weight of a 1st (meth) acrylic acid ester polymer (A) is 500,000-3 million, Preferably it is 700,000-2,500,000, Especially preferably, it is 1 million-2 million. In other words, the first (meth) acrylic acid ester polymer (A) is a high molecular weight polymer component.

Since the weight average molecular weight of a 1st (meth) acrylic acid ester polymer (A) exists in the said range, and polymer (A) has a comparatively large molecular weight, it is estimated that the said structure X is formed satisfactorily.

Here, when the weight average molecular weight of a 1st (meth) acrylic acid ester polymer (A) is less than 500,000, the adhesive gel fraction obtained may fall, and there exists a possibility that durability and rework property may be inferior. Moreover, when the weight average molecular weight of a 1st (meth) acrylic acid ester polymer (A) exceeds 3 million, compatibility with a 2nd (meth) acrylic acid ester polymer (B) etc. will deteriorate, haze value will increase, or a desired There is a fear that stress relaxation cannot be obtained.

The ratio of the second (meth) acrylic acid ester polymer (B) to 100 parts by mass of the first (meth) acrylic acid ester polymer (A) is preferably 5 to 50 parts by mass, more preferably 5 to 40 parts by mass, It is especially preferable that it is 10-30 mass parts.

The adhesive obtained from the adhesive composition containing a 1st (meth) acrylic acid ester polymer (A) and a 2nd (meth) acrylic acid ester polymer (B) in the said ratio is estimated to form the said structure X favorably.

As a crosslinking agent (C), an isocyanate crosslinking agent, an epoxy crosslinking agent, an aziridine crosslinking agent, a metal chelate crosslinking agent, etc. are mentioned preferably.

Isocyanate-based crosslinking agents include at least a polyisocyanate compound. As a polyisocyanate compound, For example, aromatic polyisocyanate, such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylene diisocyanate, aliphatic polyisocyanate, such as hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, for example. Alicyclic polyisocyanates such as isocyanates, and their reactants with low molecular weight active hydrogen-containing compounds such as biuret bodies, isocyanurates, and ethylene glycol, propylene glycol, neopentyl glycol, trimetholpropane and castor oil. Adduct body etc. are mentioned. Among them, tolylene diisocyanate (TDI-based) adduct of trimethyrolpropane is particularly preferred because it can impart proper rigidity and flexibility to the resulting crosslinked structure.

As an epoxy type crosslinking agent, it is 1, 3-bis (N, N'- diglycidyl aminomethyl) cyclohexane, N, N, N ', N'- tetraglycidyl-m- xylene diamine, for example. , Ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimetholpropane diglycidyl ether, diglycidyl aniline, diglycidyl amine and the like.

As an aziridine system crosslinking agent, it is diphenylmethane-4,4'-bis (1-aziridine carboxamide), a trimetholpropane tri- (beta)-aziridinyl propionate, tetrametholmethane tri-, for example. β-aziridinylpropionate, toluene-2,4-bis (1-aziridinecarboxamide), triethylene melamine, bisisophthalaroyl-1- (2-methylaziridine), tris-1- (2 -Methylaziridine) phosphine, trimetholpropane tri-β- (2-methylaziridine) propionate, etc. are mentioned.

As a metal chelate crosslinking agent, although a metal atom has chelate compounds, such as aluminum, zirconium, titanium, zinc, iron, and tin, an aluminum chelate compound is preferable from a performance viewpoint. Examples of the aluminum chelate compound include diisopropoxy aluminum monooleyl acetoacetate, monoisopropoxy aluminum bisoleyl acetoacetate, monoisopropoxy aluminum monooleate monoethyl acetoacetate, and diisopropoxy aluminum. Monolauryl acetoacetate, diisopropoxy aluminum monostearyl acetoacetate, diisopropoxy aluminum monoisostearyl acetoacetate, etc. are mentioned.

As for content of a crosslinking agent (D), the crosslinkable group (for example, isocyanate group) of the said crosslinking agent (D) is a thing of the reactive functional group (b1) (for example, hydroxyl group) of a 2nd (meth) acrylic acid ester polymer (B). The amount is usually from 0.05 to 5 equivalents, preferably from 0.1 to 3.5 equivalents, particularly preferably from 0.3 to 1.0 equivalents. When the quantity of the said crosslinkable group is less than 0.05 equivalent, the adhesive gel fraction obtained will be less than 30%, and there exists a possibility that sufficient cohesion force may not be exhibited. Moreover, if the quantity of the said crosslinkable group is more than 0.1 equivalent, especially 0.3 equivalent or more, the adhesive obtained can be made more durable. On the other hand, if the quantity of the said crosslinkable group is 3.5 equivalent or less, the adhesive obtained can be made excellent in rework property. Furthermore, if the amount of the crosslinkable group is 1.0 equivalent or less, it is assumed that the crosslinking agent (D) can be contributed only to the formation of the three-dimensional network structure of the polymer (B), so that crosslinking of the polymer (A) can be effectively prevented. As a result, the obtained adhesive becomes excellent in stress relaxation property.

In addition, in this embodiment, as a crosslinking agent (D), the reactive functional group (b1) of a 2nd (meth) acrylic acid ester polymer (B) and the reactive functional group (a1) of a 1st (meth) acrylic acid ester polymer (A) As long as it is a crosslinking agent of the kind in which the reactivity relationship with all is the same, you may use multiple types of things together. From the viewpoint of facilitating control of the three-dimensional network structure formed by the second (meth) acrylic acid ester polymer (B), it is preferable to use only one type of crosslinking agent as a functional group, for example, using only an isocyanate crosslinking agent. Furthermore, it is particularly preferable to use only one crosslinking agent as a compound.

Here, as a combination of a crosslinking agent (D) and the reactive functional group containing monomer of each of (meth) acrylic acid ester polymer (A) and (B), when a crosslinking agent (D) is an isocyanate type crosslinking agent, the reactivity of a polymer (A) Examples of the functional group (a1) -containing monomer include a carboxyl group-containing monomer, a reactive functional group (b1) -containing monomer of the polymer (B), and a hydroxyl-containing monomer or an amino group-containing monomer (particularly a hydroxyl group-containing monomer), and a reactive functional group (b2) -containing monomer of the polymer (B). As the monomer, a carboxyl group-containing monomer is preferably selected.

On the other hand, when the crosslinking agent (D) is an epoxy crosslinking agent, an aziridine crosslinking agent or a metal chelate crosslinking agent, as the reactive functional group (a1) -containing monomer of the polymer (A), the hydroxyl group-containing monomer and the reactive functional group (b1) of the polymer (B) As a containing monomer, a carboxyl group-containing monomer and a hydroxyl-containing monomer are preferable as a reactive functional group (b2) containing monomer of a polymer (B).

Flexibility of the bond formed between the crosslinking agent (D) and the polymer (B) and mildness of the crosslinking reaction, in addition, the adhesion durability of the pressure-sensitive adhesive obtained by appropriately reacting the reactive group of the polymer (A) with the silane coupling agent (E) In view of contributing to the crosslinking agent (D), the isocyanate-based crosslinking agent, the reactive functional group (a1) -containing monomer of the polymer (A) are used as the carboxyl group-containing monomer, and the reactive functional group (b1) -containing monomer of the polymer (B) as the hydroxyl group-containing monomer. It is especially preferable not to use a reactive functional group (b2) -containing monomer.

As antistatic agent (C), what is necessary is just to be able to provide antistatic property to the adhesive obtained, without impairing the effect of this invention, For example, an ionic compound, surfactant, etc. are mentioned, Especially, ionic Compounds are preferred. The ionic compound may be a liquid or may be a solid. Here, the ionic compound in the present specification refers to a compound in which positive and negative ions are mainly linked by electrostatic attraction.

As the ionic compound, nitrogen onium salts, sulfur-containing onium salts, phosphorus onium salts, alkali metal salts and alkaline earth metal salts are preferable. On the other hand, as an alkali metal salt, lithium salt and potassium salt are preferable. Specific examples of such ionic compounds include N-butyl-4-methyl pyridinium hexa fluorine phosphite, N-hexyl-4-methyl pyridinium hexa fluorine phosphite, N-butyl-2-hexyl pyridinium pachlorate, bis (Fluorosulfonimide) Potassium (KFSI), Bis (Fluorosulfonylimide) Lithium (LiFSI), Bis (Trifluoromethane sulfonimide) Potassium, Bis (Trifluoromethane sulfonimide) Lithium (LiTFSI ), N-butyl-2-hexyl pyridinium bis (trifluoromethane sulfonyl) imide, and the like. The above antistatic agent (C) may be used individually by 1 type, and may be used in combination of 2 or more type.

It is preferable that content of the antistatic agent (C) in the adhesive composition which concerns on this embodiment is 0.1-30 mass%, It is especially preferable that it is 0.5-20 mass%, Furthermore, it is preferable that it is 1.0-10 mass%. . When content of antistatic agent (C) exists in the said range, antistatic property can be exhibited effectively and content of other components (A), (B), and (D) in the adhesive composition which concerns on this embodiment is ensured. can do.

In addition, although it is also preferable to use antistatic agent (C) independently, it is also preferable to use a dispersing agent together. When the solubility of the antistatic agent (C) in an adhesive composition is not enough, it is because solubility can be improved by using a dispersing agent together.

As a dispersing agent, an alkylene glycol dialkyl ether etc. are mentioned preferably, for example. Specific examples of the alkylene glycol dialkyl ether include octa ethylene glycol dibutyl ether, octa ethylene glycol diethyl ether, octa ethylene glycol dimethyl ether, hexa ethylene glycol dibutyl ether, hexa ethylene glycol diethyl ether, hexa ethylene glycol dimethyl ether, Tetraethylene glycol dibutyl ether, tetraethylene glycol diethyl ether, tetraethylene glycol dimethyl ether (hereinafter may be referred to as "tetra glide"), triethylene glycol diethyl ether, triethylene glycol dimethyl ether, and the like. have. These dispersants may be used individually by 1 type, and may be used in combination of 2 or more type.

As a compounding quantity of a dispersing agent, it is preferable that it is 0.5-1.5 in a molar ratio with respect to antistatic agent (C), It is more preferable that it is 0.7-1.2, It is especially preferable that it is 0.9-1.1.

On the other hand, as above-mentioned, a 1st (meth) acrylic acid ester polymer (A) or a 1st (meth) acrylic acid ester polymer (A) and a 2nd (meth) acrylic acid ester polymer (B) have an oxyalkylene group containing monomer. When it contains as a structural unit, content of antistatic agent (C) can be reduced. Specifically, content in the adhesive composition which concerns on this embodiment becomes like this. Preferably it is 0.5-15 mass%, Especially preferably, it can be set as the range of 1.0-5.0 mass%.

The adhesive composition which concerns on this embodiment, Preferably contains a silane coupling agent (E) further. When the said (silane) coupling agent (E) is contained, when the 1st (meth) acrylic acid ester polymer (A) has a carboxyl group, the organic reactive group of a silane coupling agent (E), etc., and a 1st (meth) acrylic acid ester polymer (A The carboxyl group of) reacts, and the alkoxysilyl group of the silane coupling agent (E) and the like act on the surface of the adherend such as a glass substrate. For this reason, when bonding a polarizing plate, for example to a liquid crystal glass cell etc., adhesiveness between an adhesive and a liquid crystal glass cell becomes more favorable. On the other hand, when the reactive functional group (a1) of the polymer (A) is other than a carboxyl group, the organic reactive group of the silane coupling agent (E) that functions with the reactive functional group (a1) is appropriately selected in accordance with the reactive functional group (a1).

As said silane coupling agent (E), it is an organosilicon compound which has at least one alkoxysilyl group in a molecule | numerator, the thing with favorable compatibility with an adhesive component, and having a light transmittance, for example, a substantially transparent thing are suitable. It is preferable that it is 0.01-1.0 mass part with respect to 100 mass parts of 1st (meth) acrylic acid ester polymers (A), and, as for the addition amount of such a silane coupling agent (E), it is especially preferable that it is 0.05-0.5 mass part.

Specific examples of the silane coupling agent (D) include polymerizable unsaturated group-containing silicon compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, and methacryloxypropyltrimethoxysilane, and 3-glycidoxypropyltrimethoxysilane Silicon compounds having an epoxy structure such as 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxy And amino group-containing silicon compounds such as silane and N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, and 3-isocyanatepropyltriethoxysilane. These may be used individually by 1 type and may be used in combination of 2 or more type.

If desired, various additives commonly used in acrylic pressure-sensitive adhesives, for example, tackifiers, antioxidants, ultraviolet absorbers, light stabilizers, softeners, fillers, refractive index adjusters, and the like can be added to the pressure-sensitive adhesive composition.

The said adhesive composition produces each of a 1st (meth) acrylic acid ester polymer (A) and a 2nd (meth) acrylic acid ester polymer (B), mixes them, and at the same time crosslinking agent (D), It can manufacture by adding an antistatic agent (C) and a silane coupling agent (E) as needed.

As a preferable specific example, (meth) acrylic acid ester polymer (A) and (B) are manufactured separately by a normal radical polymerization method, respectively. The polymerization of the (meth) acrylic acid ester polymers (A) and (B) can be carried out by a solution polymerization method or the like, using a polymerization initiator if desired. As a polymerization solvent, ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone etc. are mentioned, for example, You may use two or more types together.

As a polymerization initiator, an azo compound, an organic peroxide, etc. are mentioned, You may use two or more types together. As an azo type compound, 2, 2'- azobisisobutyronitrile, 2, 2'- azobis (2-methylbutyronitrile), 1, 1'- azobis (cyclohexane 1-carbo, for example) Nitrile, 2, 2'-azobis (2, 4-dimethylvaleronitrile), 2, 2'-azobis (2, 4-dimethyl-4-methoxyvaleronitrile), dimethyl 2, 2'-azo Bis (2-methylpropionate), 4, 4'-azobis (4-cyanobareric acid), 2, 2'-azobis (2-hydroxymethylpropionitrile), 2, 2'-azo Bis [2- (2-imidazolin-2-yl) propane] and the like.

Examples of the organic peroxide include benzoyl peroxide, t-butylperbenzoate, cumene hydroxide peroxide, diisopropylperoxydicarbonate, di-n-propylperoxydicarbonate, di (2-ethoxyethyl) peroxydicarbonate , t-butyl peroxy neodecanoate, t-butyl peroxy vivarate, (3, 5, 5- (trimethylhexanoyl) peroxide, dipropionyl peroxide, diacetyl peroxide and the like.

In addition, in the said superposition | polymerization process, the weight average molecular weight of the polymer obtained can be adjusted by mix | blending chain transfer agents, such as 2-mercaptoethanol.

Next, the solution of the obtained polymers (A) and (B) is mixed and a dilution solvent is added. Then, the crosslinking agent (D), an antistatic agent (C), and a silane coupling agent (E) are added as needed, and it mixes sufficiently, and the adhesive composition (coating solution) diluted with the solvent is obtained.

As a diluting solvent for diluting an adhesive composition to make a coating solution, For example, aliphatic hydrocarbons, such as hexane, heptane, cyclohexane, aromatic hydrocarbons, such as toluene and xylene, halogenated hydrocarbons, such as methylene chloride and ethylene chloride, methanol, ethanol Alcohols such as propanol, butanol and 1-methoxy-2-propanol, ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone and cyclohexanone, esters such as ethyl acetate and butyl acetate, and ethylcell Cellosolve solvents, such as a solvent, etc. can be used.

As a density | concentration and a viscosity of the coating solution manufactured in this way, what is necessary is just a range which can be coated, and it does not restrict | limit especially, It can select suitably according to a situation. For example, it dilutes so that the density | concentration of an adhesive composition may be 10-40 mass%. On the other hand, when obtaining a coating solution, addition of a dilution solvent etc. is not a requirement, and if it is a viscosity etc. which an adhesive composition can coat, it is not necessary to add a dilution solvent. In this case, an adhesive composition turns into a coating solution as it is.

The adhesive mentioned above is obtained by crosslinking the said adhesive composition. Crosslinking of the said adhesive composition can be performed by heat processing. In addition, this heat processing can also serve as the drying process at the time of volatilizing the dilution solvent etc. of an adhesive composition.

When performing heat processing, it is preferable that heating temperature is 50-150 degreeC, and it is especially preferable that it is 70-120 degreeC. Moreover, it is preferable that heating time is 30 second-3 minutes, and it is preferable that it is 50 second-2 minutes especially. Moreover, it is especially preferable to set a curing period of about 1 to 2 weeks at normal temperature (for example, 23 degreeC, 50% RH) after heat processing.

By the above heat treatment (and curing), the second (meth) acrylic acid ester polymer (B) is crosslinked by the crosslinking agent (D), and the first (meth) acrylic acid ester polymer (A) is added to the three-dimensional network structure. Inserted, it is assumed that the structure X is formed. In the case where the first (meth) acrylic acid ester polymer (A) has a carboxyl group, the first (meth) acrylic acid ester polymer (A) is reacted with a silane coupling agent (E) to a glass substrate such as a liquid crystal cell of an adhesive obtained. Can improve the adhesion durability.

The elongation at break by the tensile test of the pressure-sensitive adhesive according to the present embodiment is 1500% or more, preferably 2000% or more, particularly preferably 2500% or more. In addition, this breaking elongation is measured as a single adhesive layer which does not involve a base material or the like. When the pressure-sensitive adhesive made of the above-described material has such a large breaking elongation, the pressure-sensitive adhesive can be excellent in stress relaxation resistance and excellent in both light leakage resistance and durability.

Specifically, the tensile test was performed on a pressure-sensitive adhesive formed with a thickness of 500 μm, a width of 10 mm, and a length of 75 mm in the stretching direction (of which the length of the measurement site was 20 mm) at a speed of 200 mm / min under an environment of 23 ° C. and 50% RH. It is to be carried out by stretching.

The pressure-sensitive adhesive gel fraction according to the present embodiment is 30 to 90%, preferably 40 to 80%, and particularly preferably 45 to 75%. Since the gel fraction, that is, the degree of crosslinking is in this range, the three-dimensional network structure by crosslinking of the second (meth) acrylic acid ester polymer (B) is formed satisfactorily, and the pressure-sensitive adhesive has excellent light leakage and durability. Can be to In addition, an adhesive gel fraction is a value in the case of sticking (it passed the curing period). Specifically, after apply | coating an adhesive composition to a peeling sheet and heat-processing, it means the gel fraction after storing (curing) for 7 days in 23 degreeC and 50% RH environment. This is because the value of the pressure-sensitive adhesive gel fraction varies before the curing period elapses. From this point of view, if it is unclear whether the curing period has elapsed, the gel fraction should be within the above range after 7 days of storage at 23 ° C. and 50% RH.

It is preferable that the surface resistance value of the adhesive which concerns on this embodiment is 3.0x10 <^{11> (} ohm) / sq or less, It is especially preferable that it is 1.0x10 <^{11> (} ohm) / sq or less, Furthermore, it is preferable that it is 8.0x10 <^{10> (} ohm) / sq or less. Sufficient antistatic property can be exhibited when surface resistance value is below the said value. Moreover, in this embodiment, even if content of the antistatic agent (C) in the said adhesive composition is 3 mass% or less, sufficient antistatic property can be exhibited as mentioned above.

It is preferable that the adhesive force with respect to the alkali free glass of the adhesive force which concerns on this embodiment is 0.1-50 N / 25 mm, It is especially preferable that it is 0.5-30 N / 25 mm, Furthermore, it is preferable that it is 3.0-20 N / 25 mm. . In addition, adhesive force here means 180 degree pull-out adhesive force (peel rate 300mm / min) based on JISZ0237, and pressurizes at 0.5 MPa and 50 degreeC for 20 minutes, and affixes to a to-be-adhered body, 23 degreeC and 50% It shall be measured after leaving for 24 hours under conditions of RH. Since adhesive force exists in the said range, when it applies to optical members, such as a polarizing plate, lifting, peeling, etc. can be prevented.

The adhesive described above can be used suitably for an optical member, For example, adhesion of optical members, such as a polarizing plate (polarizing film) and retardation plate (phase difference film), or a polarizing plate (polarizing film) and retardation plate (phase difference), for example Film) and glass substrates. Since the adhesive which concerns on this embodiment has antistatic property, static electricity does not generate | occur | produce and the defect resulting from static electricity can be suppressed effectively. In addition, since the pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive is very excellent in stress relaxation property, even when the size of the adherend is large, the stress that can be generated by the size change can be absorbed and relaxed in the pressure-sensitive adhesive layer. Therefore, the light leakage can be effectively prevented when used for the optical member as described above without peeling off the adherend over a long period of time. In other words, the pressure-sensitive adhesive according to the present embodiment achieves compatibility with light leakage and durability while having antistatic properties.

[Adhesion sheet]

As shown in FIG. 1, the adhesive sheet 1A which concerns on 1st Embodiment has the adhesive sheet 11 laminated | stacked on the peeling sheet 12 and the peeling surface of the peeling sheet 12 in order from the bottom. And the base material 13 laminated on the pressure-sensitive adhesive layer 11.

In addition, as shown in FIG. 2, the adhesive sheet 1B which concerns on 2nd Embodiment is made to contact the peeling surface of two peeling sheets 12a and 12b and those two peeling sheets 12a and 12b. It consists of the adhesive layer 11 sandwiched between the said 2 sheets of peeling sheets 12a and 12b. In addition, the peeling surface of a peeling sheet in this specification means the surface which has peelability in a peeling sheet, and includes both the surface which performed peeling process and the surface which shows peelability, even without peeling process.

In any adhesive sheet 1A, 1B, the adhesive layer 11 consists of an adhesive (an adhesive formed by bridge | crosslinking the adhesive composition mentioned above) which concerns on this embodiment.

Although the thickness of the adhesive layer 11 is suitably determined according to the purpose of use of the adhesive sheets 1A and 1B, it is usually 5-100 micrometers, Preferably it is the range of 10-60 micrometers, For example, for optical members, especially a polarizing plate When using as an adhesive layer, it is 10-50 micrometers, It is preferable that it is 10-30 micrometers especially.

There is no restriction | limiting in particular as the base material 13, Any thing used as a base material sheet of a normal adhesive sheet can be used. For example, woven or nonwoven fabrics using fibers of other desired optical members, such as rayon, acrylic, polyester, etc .; Paper such as quality paper, glassine paper, impregnated paper and coated paper; Metal foils such as alumina and copper; Foams such as urethane foams and polyethylene foams; Polyester films such as polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate, polyurethane films, polyethylene films, polypropylene films, cellulose films such as triacetyl cellulose, polyvinyl chloride films, polyvinylidene chloride films, poly Plastic films such as vinyl alcohol films, ethylene-vinyl acetate copolymer films, polystyrene films, polycarbonate films, acrylic resin films, norbornene-based resin films, and cycloolefin resin films; These 2 or more types of laminated bodies etc. are mentioned. The plastic film may be uniaxially extended or biaxially extended.

As an optical member, a polarizing plate (polarizing film), a polarizer, a retardation plate (retardation film), a viewing angle compensation film, a brightness improvement film, a contrast improvement film, a liquid crystal polymer film, etc. are mentioned, for example. Among these, since a polarizing plate (polarizing film) is easy to shrink | contract and has a big dimension change, it is suitable as an object of forming the adhesive (the said adhesive layer 11) of this embodiment from a light-proof leak-proof viewpoint.

Although the thickness of the base material 13 changes also with the kind, For example, in the case of an optical member, it is 10 micrometers-500 micrometers normally, Preferably they are 50 micrometers-300 micrometers.

As the release sheets 12, 12a and 12b, for example, polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film , Polyethylene naphthalate film, polybutylene terephthalate film, polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene- (meth) acrylic acid copolymer film, ethylene- (meth) acrylic acid ester copolymer film, polystyrene film , Polycarbonate film, polyimide film, fluororesin film and the like can be used. Moreover, such a crosslinked film can also be used. Furthermore, such a laminated film may be sufficient.

It is preferable that the peeling process of the said peeling sheet is carried out to the peeling surface (especially the surface which contact | connects the adhesive layer 11). As a peeling agent used for a peeling process, alkyd type, silicone type, fluorine type, unsaturated polyester type, polyolefin type, and wax type peeling agent are mentioned, for example.

Although there is no restriction | limiting in particular about the thickness of release sheet 12, 12a, 12b, Usually, it is about 20-150 micrometers.

In order to manufacture the said adhesive sheet 1A, after apply | coating the solution (coating solution) containing the said adhesive composition to the peeling surface of the peeling sheet 12, and heat-processing to form the adhesive layer 11, The base material 13 is laminated | stacked on the adhesive layer 11. After that, it is preferable to set the curing period.

In addition, the conditions of heat processing and curing are as above-mentioned.

Moreover, in manufacturing the said adhesive sheet 1B, the coating solution containing the said adhesive composition is apply | coated to the peeling surface of one peeling sheet 12a (or 12b), and it heat-processes the adhesive layer 11 ), The peeling surface of the other peeling sheet 12b (or 12a) is superimposed on the adhesive layer 11.

As a method of apply | coating the said coating solution, the bar coat method, the knife coat method, the roll coat method, the braid coat method, the die coat method, the gravure coat method, etc. can be used, for example.

Here, for example, in manufacturing the liquid crystal display device which consists of a liquid crystal cell and a polarizing plate, the polarizing plate is used as the base material 13 of the adhesive sheet 1A, and the peeling sheet 12 of the said adhesive sheet 1A is carried out. It is good to peel off and bond the exposed adhesive layer 11 and liquid crystal cell together.

In addition, for example, to manufacture a liquid crystal display device in which a retardation plate is disposed between a liquid crystal cell and a polarizing plate, as an example, first, one peeling sheet 12a (or 12b) of the adhesive sheet 1B is peeled off. The exposed adhesive layer 11 and the retardation plate of the adhesive sheet 1B are bonded together. Next, the peeling sheet 12 of the adhesive sheet 1A using the polarizing plate as the base material 13 is peeled off, and the exposed adhesive layer 11 and the retardation plate of the adhesive sheet 1A are bonded together. Furthermore, the other peeling sheet 12b (or 12a) is peeled from the adhesive layer 11 of the said adhesive sheet B, and the exposed adhesive layer 11 and liquid crystal cell of the adhesive sheet B are bonded together. .

According to the above adhesive sheets 1A and 1B, since the adhesive layer 11 has antistatic property, static electricity does not generate | occur | produce and the defect resulting from static electricity can be suppressed effectively. In addition, since the pressure-sensitive adhesive layer 11 is extremely excellent in stress relaxation property, even if it is applied to adhesion of the polarizing plate, for example, even if it is applied to adhesion of the polarizing plate, the stress that can be generated by the deformation of the polarizing plate can be absorbed and relaxed by the pressure-sensitive adhesive layer 11. It is estimated that excellent light leakage resistance and high durability are exhibited by this.

The embodiments described above are described for ease of understanding of the present invention, and are not described for limiting the present invention. Therefore, each element disclosed in the said embodiment is the meaning including all the design changes and equivalents which belong to the technical scope of this invention.

For example, the peeling sheet 12 of the adhesive sheet 1A may be omitted, and either one of the peeling sheets 12a and 12b in the adhesive sheet 1B may be omitted.

[Examples]

Hereinafter, although an Example etc. demonstrate this invention further more concretely, the scope of the present invention is not limited to these Examples.

EXAMPLE 1

 75.0 parts by mass of n-butyl acrylate, 20.0 parts by mass of 2-methoxyethyl acrylate, 5.0 parts by mass of acrylic acid, 200 parts by mass of ethyl acetate, and 2 to a reaction vessel equipped with a stirrer, a thermometer, a reflux cooler, a dropping device, and a nitrogen introduction tube. And 0.08 parts by mass of 2 ”-azobisisobutyronitrile were placed and the air in the reaction vessel was replaced with nitrogen gas. While stirring under this nitrogen atmosphere, the reaction solution was heated to 60 ° C, reacted for 16 hours, and then cooled to room temperature. Here, the molecular weight was measured by the method of mentioning a part of obtained solution later, and production | generation of the polymer (A) of the weight average molecular weight 1.2 million was confirmed.

2. Preparation of Polymer (B)

85.0 parts by mass of n-butyl acrylate, 15.0 parts by mass of 2-hydroxyethyl acrylate, 200 parts by mass of ethyl acetate, 2, 2 ”-azo in a reaction vessel equipped with a stirrer, a thermometer, a reflux cooler, a dropping device, and a nitrogen introduction tube. 0.16 mass part of bisisobutyronitrile and 0.3 mass part of 2-mercaptoethanols were put, and the air in the said reaction container was substituted by nitrogen gas. While stirring under this nitrogen atmosphere, the reaction solution was heated to 70 ° C, reacted for 6 hours, and then cooled to room temperature. Here, molecular weight was measured by the method of mentioning a part of obtained solution later, and production | generation of the polymer (B) of 60,000 weight average molecular weight was confirmed.

3. Preparation of Adhesive Composition

After mixing 100 mass parts (solid content conversion value) of the polymer (A) obtained at the said process (1), and 15 mass parts (solid content conversion value) of the polymer (B) obtained at the said process (2), as a crosslinking agent (D) And 2.21 parts by mass of tolylene diisocyanate (TDI-based) adduct (from Nippon Polyurethane Co., "trade name" Colonate L ") of trimetholpropane in an amount corresponding to 0.6 equivalent of hydroxyl group of the polymer (B) was added. Finally, 2.0 parts by mass of N-butyl-4-methylpyridinium hexafluorophosphite as the antistatic agent (C) and 3-glycidoxypropylmethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., brand name) as the silane coupling agent (E). 0.2 mass part of "KBM403" was added, and the mixture was sufficiently stirred to obtain a dilute solution of the adhesive composition.

Here, the mixing | blending of this adhesive composition is shown in Table 1. In addition, the details, such as the symbol of Table 1, are as follows.

[Polymer (A) and B)]

BA: n-butyl acrylate

AA: acrylic acid

MA: Methacrylic acid

MEA: 2-methoxyethyl acrylate

HEA ： Acrylic acid hydroxyethyl

4HBA ： Acrylic acid-hydroxybutyl

PhEA: Phenoxyethyl acrylate

[Isocyanate Crosslinking Agent (D)]

Collonate L: tolylene diisocyanate adduct of trimetholpropane (manufactured by Nippon Polyurethanes, trade name "Colonate L")

Colonate HX: Hexamethylene diisocyanate type isocyanurate (Nippon Polyurethanes company, brand name "Colonate HX")

Duranate 24A-100: Hexamethylene diisocyanate system burette (Asahi Kasei Chemical Co., Ltd. make, brand name "duranate 24A-100")

[Antistatic Agent (C)]

Pyridinium: N-butyl-4-methyl pyridinium hexa fluoro phosphite

KFSI: Bis (Fluorosulfonylimide) Potassium (KFSI): Mixed solution of tetraglyme = 1: 1 (mass ratio) ※ The compounding quantity in a table | surface is a value only for KFSI

LiTFSI: Bis (trifluoromethanesulfonylimide) lithium (LiTFSI): Mixed solution of tetraglyme = 1: 1 (mass ratio) ※ The compounding quantity in the table is a value only for LiTFSI

AS-804: Daiichi Kogyo Seiyaku Co., Ltd., onium salt type antistatic agent, brand name "AS-804"

[Silane Coupling Agent (E)]

KBM403: 3-glycidoxypropylmethoxysilane (product made in Shin-Etsu Chemical Co., Ltd., brand name "KBM403")

KBE9007: 3-isocyanatepropyltriethoxysilane (Shin-Etsu Chemical Co., Ltd. make, brand name "KBE9007")

X-41-1059A: oligomer-based silane coupling agent (Shin-Etsu Chemical Co., Ltd., brand name "X-41-1059A")

Knife coater so that the thickness after drying may be 25 micrometers on the peeling process surface of the peeling sheet (The Lintec company make SP-PET3x11, thickness: 3 micrometers) which peeled the single side | surface of a polyethylene terephthalate film with the silicone type peeling agent in the diluted solution of the obtained adhesive composition. After apply | coating to, it heat-processed at 90 degreeC for 1 minute, and formed the adhesive layer.

Next, the polarizing plate which consists of a polarizing film with a disk liquid crystal layer and the viewing angle expansion film integrated is bonded together so that the exposed surface of the said adhesive layer and the surface of a disk liquid crystal layer may contact, 23 degreeC, 50% By curing for 7 days in RH, the polarizing plate with an adhesive layer was obtained.

[Examples 2 to 26 and Comparative Examples 1 to 3]

Except changing the kind and proportion of each monomer which comprises an adhesive composition, the kind and compounding quantity of a crosslinking agent, an antistatic agent, and a silane coupling agent, and the compounding ratio of a polymer (A) and a polymer (B) to show in Table 1, an Example In the same manner as in 1, a polarizing plate with an adhesive layer was produced.

Here, the weight average molecular weight (Mw) mentioned above is the weight average molecular weight of polystyrene conversion measured (GPC measurement) on condition of the following using gel permeation chromatography (GPC).

<Measurement Conditions>

GPC measuring device: manufactured by Tosoh Corporation, HLC-8020

GPC column (passed in the following order): manufactured by Tosoh Corporation

  TSK guard column HXL-H

  TSK gel GMHXL (× 2)

  TSK gel G2000 HXL

Measurement solvent: tetrahydrofuran

Measurement temperature: 40 ℃

In the Example or the comparative example, using the peeling sheet (SP-PET3801 made from Lintec, thickness: 38 micrometers) which replaced with the polarizing plate used for preparation of the polarizing plate with an adhesive layer, and peeled the single side | surface of a polyethylene terephthalate film with the silicone type peeling agent, An adhesive sheet was produced. Specifically, the release sheet was laminated so that the release treatment surface side was in contact with the exposed adhesive layer of the structure composed of the release sheet / adhesive layer (thickness: 25 μm) obtained in the manufacturing process of the example or the comparative example. This produced the adhesive sheet which consists of a structure of a peeling sheet / adhesive layer / peeling sheet.

The obtained adhesive sheet was cured for 7 days under the conditions of 23 degreeC and 50% RH. Thereafter, the pressure-sensitive adhesive sheet was sampled at a size of 80 mm x 80 mm, the pressure-sensitive adhesive layer was surrounded by a polyester mesh (mesh size 200), and the mass of the pressure-sensitive adhesive alone was measured by a precision balance. Let the mass at this time be M1.

Next, the adhesive enclosed with the said polyester mesh was immersed in ethyl acetate for 24 hours at room temperature (23 degreeC). Then, the adhesive was taken out, air-dried for 24 hours in the environment of the temperature of 23 degreeC, and 50% of a relative humidity, and it further dried in 80 degreeC oven for 12 hours. The mass of only the adhesive after drying was measured with the precision balance. The mass at this time is assumed to be M2. The gel fraction (%) is represented by (M 2 / M 1) × 100. The results are shown in Table 2.

[Test Example 2] (Light Leak Test)

The polarizing plate with an adhesive layer obtained by the Example or the comparative example was adjusted to 233 mm x 309 mm size using the cutting device (Super cutter made by Ogino Seisakusho Co., PN1-600). The peeling sheet was peeled off and affixed on the alkali free glass (Eagle XG, Corning Co., Ltd.) through the exposed adhesive layer, and it pressurized for 20 minutes at 0.5 Mpa and 50 degreeC by the autoclave by Kurihara Seisakusho company. On the other hand, the said bonding was performed in the front and back of an alkali free glass so that a polarizing axis with an adhesive layer might be in a cross nicol state (polarization axis: 45 degrees, 135 degrees). In this state, after leaving for 250 hours in an environment of 80 ° C. dry, it was left for 2 hours in an environment of 23 ° C. and 50% RH, and as a sample, light leakage was evaluated by the method shown below. The results are shown in Table 2.

<Light leakage evaluation: ΔL ^* >

Using the Otsuka Denshi Co., Ltd. MCPD-2000, the brightness L ^* of each area | region shown in FIG. 3 in the said sample was measured, and the brightness difference ((DELTA) L ^* ) is

ΔL ^* = [(b + c + d + e) / 4] -a

(Where a, b, c, d, and e are brightness at predetermined measurement points (one central portion of each region) of A, B, C, D, and E regions, respectively. It was set as photo-leakage. The smaller the value of ΔL ^*, the smaller the light leakage.

[Test Example 3] (Durability Evaluation)

The polarizing plate with an adhesive layer obtained by the Example or the comparative example was adjusted to 233 mm x 309 mm size using the cutting device (Super cutter made by Ogino Seisakusho Co., PN1-600). The peeling sheet was peeled off and affixed on the alkali free glass (Eagle XG, Corning Co., Ltd.) through the exposed adhesive layer, and it pressurized for 20 minutes at 0.5 Mpa and 50 degreeC by the autoclave by Kurihara Seisakusho company.

Then, it put in the environment of each durable condition below, and observed after 500 hours using the 10 times magnifier. The appearance change was based on the following. The results are shown in Table 2.

◎: There is not a fault in four sides

(Circle): No flaw in the part more than 0.6mm from the outer peripheral end in 4 sides

X: At least 1 side of 4 sides has an external defect of 0.1 mm or more of adhesives, such as lifting, peeling, foaming, and a stripe, in a part 0.6 mm or more from an outer peripheral end part.

 <Durability>

80 ℃ dry

60 ° C, 90% RH

[Test Example 4] (Measurement of Adhesive Force)

The polarizing plate with an adhesive layer obtained by the Example or the comparative example was cut out, and the sample of 25 mm width and 100 mm length was produced. The peeling sheet was peeled from the sample, the sample was affixed to an alkali-free glass (Eagle XG, Corning Corporation) through the exposed pressure-sensitive adhesive layer, and then 0.5 MPa and 50 ° C. in an autoclave manufactured by Kurihara Seisakusho Co., Ltd. for 20 minutes. Pressurized. Then, after leaving for 24 hours at 23 degreeC and 50% RH conditions, using the tension test machine (Orientech Co., Ltd. Tensile), adhesive force (after 1 day of sticking) on the conditions of peeling rate 300mm / min, peeling angle 180 degrees. Adhesive force of N / 25mm) was measured. The results are shown in Table 2.

Test Example 5 (Measurement of Surface Resistance)

The polarizing plate with an adhesive layer obtained by the Example or the comparative example was cut | disconnected in the magnitude | size of 50 mm x 50 mm, and the obtained sample was left to stand at the temperature of 23 degreeC, and humidity of 50% RH for 24 hours. Thereafter, the peeling sheet was peeled off, and the surface resistance value (Ω / sq) was measured according to JIS K6911 using a resistivity meter (manufactured by Mitsubishi Chemical Co., Ltd., Hirester UP MCP-HT450 type) on the exposed adhesive layer surface. It was. The results are shown in Table 2.

[Test Example 6] (Measurement of Breaking Elongation)

The pressure-sensitive adhesive composition prepared in the Examples or Comparative Examples was applied to the peeling treatment surface of the release sheet (SP-PET3811, manufactured by Lintec Co., Ltd.), in which one side of the polyethylene terephthalate film was peeled off with a silicone release agent, so that the coating thickness after drying was 25 μm. And it heated at 100 degreeC for 1 minute, and formed the adhesive layer. The adhesive layer and the peeling process surface of the other peeling sheet (SP-PET3801 made from Lintec, Inc.) which peeled the single side | surface of a polyethylene terephthalate film with the silicone type peeling agent were bonded together, and the adhesive sheet was obtained.

The said adhesive layer was laminated in multiple layers so that the total thickness of the adhesive layer in the said adhesive sheet might be 500 micrometers, and only the peeling sheet of the outermost layer of a laminated body was left, and it was left to stand for two weeks in 23 degreeC and 50% RH atmosphere. Thereafter, a 10 mm wide x 75 mm long sample was cut out from the pressure sensitive adhesive sheet in which the pressure sensitive adhesive layer was laminated in multiple layers, and the release sheet laminated on the outermost layer of the laminate was peeled off, and the sample measurement site was 10 mm wide x 20 mm long (extension direction). ), The sample was set, and it extended | stretched at the tensile speed of 200 mm / min using the tensile tester (Tensilon by Orientec Co., Ltd.) in the environment of 23 degreeC and 50% RH, and the elongation at break (%) was measured. The results are shown in Table 2.

As can be seen from Table 2, in the polarizing plate with the pressure-sensitive adhesive layer obtained in the example, the adhesive layer had sufficient adhesive strength and antistatic property, and the elongation at break was 1500% or more, showing excellent stress relaxation property, Everyone was excellent.

The adhesive of this invention is suitable for adhesion | attachment of an optical member, for example, a polarizing plate and a retardation plate, and the adhesive sheet of this invention is suitable as an adhesive sheet for optical members, such as a polarizing plate and a retardation plate.

1A, 1B... Adhesive sheet
11 ... The pressure-
12, 12a, 12b... Peeling sheet
13 ... materials

Claims (10)

The weight average molecular weight is 500,000 to 3 million first (meth) acrylic acid ester polymer (A),
A component having a weight average molecular weight crosslinking a second (meth) acrylic acid ester polymer (B) of 8,000 to 300,000,
Contains an antistatic agent (C),
Elongation at break by tensile test is more than 1500%,
A pressure-sensitive adhesive, characterized in that the gel fraction is 30 to 90%. The method according to claim 1,
The ratio of the said 2nd (meth) acrylic acid ester polymer (B) with respect to 100 mass parts of said 1st (meth) acrylic acid ester polymers (A) is 5-50 mass parts, The adhesive characterized by the above-mentioned. The method according to claim 1,
The first (meth) acrylic acid ester polymer (A) or the first (meth) acrylic acid ester polymer (A) and the second (meth) acrylic acid ester polymer (B) before crosslinking are monomer units constituting the polymer. An adhesive containing 5 to 50% by mass of an oxyalkylene group-containing monomer as an adhesive. The method according to claim 1,
The antistatic agent (C) is an ionic compound, characterized in that the pressure-sensitive adhesive. The method of claim 4,
The said ionic compound is at least 1 sort (s) chosen from the group which consists of a nitrogen-containing onium salt, a sulfur-containing onium salt, a phosphorus onium salt, and an alkali metal salt. The method according to claim 1,
The said 2nd (meth) acrylic acid ester polymer (B) before crosslinking contains more than 1 mass% and less than 50 mass% of reactive functional group containing monomer as a structural component. The method of claim 6,
The second (meth) acrylic acid ester polymer (B) is crosslinked by a reaction with a crosslinking agent (D) having a crosslinkable group capable of reacting with the reactive functional group. As an adhesive sheet provided with a base material and an adhesive layer,
The said adhesive layer consists of an adhesive of any one of Claims 1-7, The adhesive sheet characterized by the above-mentioned. The method according to claim 8,
Said base material is an optical member, The adhesive sheet characterized by the above-mentioned. With two pieces of peeling sheets,
An adhesive sheet provided with the adhesive layer clamped by the said peeling sheet so that the peeling surface of the said 2 peeling sheets may be contacted,
The said adhesive layer consists of an adhesive of any one of Claims 1-7, The adhesive sheet characterized by the above-mentioned.

Images