TWI537360B - Adhesive and adhesive tape - Google Patents

Description

Adhesive and adhesive sheet

The present invention relates to an adhesive and an adhesive sheet, in particular, an adhesive for an optical member such as a polarizing plate, and an adhesive sheet. It is an object of the present invention to provide such a suitable adhesive and adhesive sheet.

In general, in the liquid crystal panel, an adhesive layer formed of an adhesive adhesive composition such as a polarizing plate and a phase difference plate adhered to a glass substrate is often used. However, the optical member such as the polarizing plate and the phase difference plate is liable to shrink due to heat or the like, that is, shrinkage due to thermal change, and as a result, the layer of the adhesive on the optical member cannot keep up with the shrinkage, thereby generating an interface. Peeling (so-called floating, peeling) causes a problem of light leakage (so-called white spots) due to the deviation of the optical axis of the optical member due to stress during shrinkage of the optical member.

As a method for preventing this problem, (1) an adhesive layer having a high adhesive force and excellent form stability is adhered to an optical member such as a polarizing plate, whereby the optical member itself is suppressed, or ( 2) A method of using an adhesive layer having a small stress when shrinking an optical member. As a method of (1), as shown in Patent Document 1, an adhesive layer having a high storage modulus is used. On the other hand, as the method of (2), an adhesive layer excellent in stress relaxation ratio which can flexibly correspond to deformation of an optical member is used. However, conventionally, in order to form such an adhesive layer excellent in stress relaxation rate, it is necessary to set the crosslinking density in the adhesive layer to be low. Thus, There is a problem that the strength of the adhesive layer itself is lowered and the durability is deteriorated.

Therefore, in Patent Documents 2 to 4, instead of setting the crosslinking density of the adhesive layer to be low, a plasticizer, a flowing paraffin, a urethane elastomer, or the like is added to the acrylic adhesive, thereby causing adhesion. The composition of the agent is moderately soft and has stress relaxation property to the adhesive layer, thereby attempting to obtain light leakage resistance and durability.

[Patent Document 1] JP-A-2006-235568

[Patent Document 2] JP-A-5-45517

[Patent Document 3] JP-A-9-137143

[Patent Document 4] JP-A-2005-194366

However, the addition of a plasticizer or a fluid paraffin adhesive composition has the difficulty that the formed adhesive layer will bleed out over time with the plasticizer and the flowing paraffin. As a result, the adhesion durability is lowered, the liquid crystal cell of the adherend is contaminated, and the like, and these various problems are worried about us. Further, in order to maintain the compatibility of the adhesive composition to which the urethane elastomer is added, there is a problem in that the addition amount of the urethane elastomer is limited and the improvement in stress relaxation property is insufficient. Further, in order to increase the stress relaxation rate, the amount of addition of the urethane elastomer is increased. However, this causes a decrease in compatibility with the acrylic pressure-sensitive adhesive, and problems such as white turbidity occur. As described above, it has been difficult in the prior art to fundamentally improve the light leakage resistance and durability of the adhesive layer formed of the adhesive composition.

The present invention has been made in view of this. An object of the present invention is to provide an adhesive and an adhesive sheet which are excellent in both light leakage resistance and durability when applied to an optical member such as a polarizing plate.

In order to achieve the above object, the present invention provides a first (meth) acrylate polymer (A) having a weight average molecular weight of 500,000 to 3,000,000 and a weight average molecular weight of 8,000 to 300,000. The component obtained by crosslinking the second (meth) acrylate polymer (B) has an elongation at break of a tensile test of 1500% or more and a gel ratio of 30 to 90%.

The adhesive of the invention (Invention 1) is a structure in which a plurality of high molecular weight polymers (A) are inserted into a three-dimensional network in which a low molecular weight polymer (B) is crosslinked (presumed), and has a large fracture. At the same time as the degree of stretching, it has a prescribed gel ratio. Thereby, the adhesive can exhibit an appropriate cohesive force and an excellent stress relaxation rate. By using such an adhesive having an excellent stress relaxation rate, when applied to an optical member such as a polarizing plate, an adhesive sheet excellent in both light leakage resistance and durability can be obtained.

In the above invention (Invention 1), the ratio of the second (meth) acrylate polymer (B) to 100 parts by mass of the first (meth) acrylate polymer (A) is preferably 5 to 50. Parts by mass (Invention 2).

In the above invention (Inventions 1 and 2), the second (meth) acrylate polymer (B) before crosslinking is preferably a constituent component of the monomer having a reactive functional group of more than 1% by mass. 50% by mass is not full (Invention 3).

In the above invention (Invention 3), the above second (meth) acrylate The polymer (B) is preferably crosslinked by reacting with a crosslinking agent (C) having a crosslinkable group reactive with the above-mentioned reactive functional group (Invention 4).

Secondly, the present invention is an adhesive sheet having a substrate and an adhesive layer, characterized in that the above-mentioned adhesive layer is composed of the above-mentioned adhesive (Inventions 1 to 4) (Invention 5).

In the above invention (Invention 5), the substrate is preferably an optical member (Invention 6).

Thirdly, the present invention is an adhesive sheet comprising two release sheets and an adhesive layer held by the release sheet, whereby the adhesive layer is in contact with the release faces of the two release sheets, and is characterized in that: The adhesive layer is composed of the above adhesives (Inventions 1 to 4) (Invention 7).

In the adhesive of the present invention, the low molecular weight polymer is chemically crosslinked to form a three-dimensional network structure in which a plurality of high molecular weight polymers are interposed and high molecular weight polymers are interposed. Constrained so that between the high molecular weight polymers, a pseudo-crosslinked structure is formed. Thus, the adhesive has a predetermined gel ratio while having a large degree of elongation at break. Thus, the adhesive can have a suitable cohesive force and excellent stress relaxation. By using such an adhesive having an excellent stress relaxation rate, when applied to an optical member such as a polarizing plate, an adhesive sheet excellent in both light leakage resistance and durability can be obtained.

Hereinafter, embodiments of the present invention will be described.

[adhesive]

The adhesive of the present embodiment contains a first (meth) acrylate polymer (A) having a weight average molecular weight (Mw) of 500,000 to 3,000,000 and a second (methyl group) having a weight average molecular weight of 8,000 to 300,000. The acrylate polymer (B) is a component formed by crosslinking. Further, in the present specification, (meth) acrylate means both acrylate and methacrylate. The same is true for other similar terms. In addition, "polymer" also contains the concept of "copolymer".

The above adhesive preferably contains a first (meth) acrylate polymer (A) having a weight average molecular weight of 500,000 to 3,000,000 and a second (meth)acrylic acid having a weight average molecular weight of 3,000 to 300,000. The adhesive composition of the ester polymer (B) and the crosslinking agent (C) is particularly preferably an adhesive composition containing a decane coupling agent (D), which is obtained by crosslinking. Among the above-mentioned adhesives, conventionally, a low molecular weight polymer as a plasticizer is used to chemically crosslink to form a three-dimensional network structure, and it is presumed that a plurality of high molecular weight polymers are inserted. The high molecular weight polymers are constrained to form a pseudo-crosslinked structure between the high molecular weight polymers. The adhesive thus obtained has a predetermined gel ratio while having a large degree of elongation at break. Thereby, the obtained adhesive can exhibit a suitable cohesive force and an excellent stress relaxation rate. Hereinafter, the above adhesive composition will be described.

The second (meth) acrylate polymer (B), (1) a monomer having a functional group (b1) which can react with the crosslinking agent (C) as a constituent component, and the polymer (B) contains The crosslinking agent (C) and the reactive functional group are substantially only the functional group (b1), (2) It is preferred that the monomer having a reactivity with the crosslinking agent (C) as a constituent component is a functional group (b1) satisfying the following formula (I), and preferably having a crosslinking agent (C) The reactivity of the monomer satisfying the functional group (b2) of the following formula (I).

Reactivity with crosslinking agent (C): functional group (b2) < functional group (b1) ... (I)

That is, in the polymer (B) which is preferably (2), the reactivity of the functional group (b1) with the crosslinking agent (C) is higher than that of the functional group (b2) with the crosslinking agent (C). Be high.

The above (meth) acrylate polymer (A) or (B) is preferably an alkyl (meth) acrylate having an alkyl group having 1 to 20 carbon atoms and having a function of reacting with the crosslinking agent (C). A monomer (a monomer containing a reactive functional group), a copolymer of another monomer used as needed. Further, the first (meth) acrylate polymer (A) preferably does not contain a monomer having the above reactive functional group.

The alkyl (meth)acrylate having an alkyl group having 1 to 20 carbon atoms, for example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, N-butyl methacrylate, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate Ester, isooctyl (meth)acrylate, n-sodium (meth)acrylate, n-lauryl (meth)acrylate, myristyl (meth)acrylate, (meth)acrylic acid Hexadecane ester and stearyl (meth)acrylate, and the like. These may be used alone or in combination of two or more. use.

On the other hand, as a monomer having a reactive functional group, a monomer having a hydroxyl group in the molecule (a monomer having a hydroxyl group), a monomer having a carboxyl group in the molecule (a monomer having a carboxyl group), and a single molecule having an amino group in the molecule A body (a monomer containing an amino group) or the like is preferred.

The hydroxyl group-containing monomer may, for example, be 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate or 3-hydroxypropyl (meth)acrylate, (methyl). A hydroxyalkyl (meth) acrylate such as 2-hydroxybutyl acrylate, 3-hydroxybutyl (meth)acrylate or 4-hydroxybutyl (meth)acrylate. These may be used alone or in combination of two or more.

The monomer having a carboxyl group may, for example, be an ethylenically unsaturated carboxylic acid such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid or citraconic acid. These may be used alone or in combination of two or more.

The amino group-containing monomer may, for example, be an aminoethyl (meth)acrylate or an n-butyl ester (meth)acrylate or the like. These may be used alone or in combination of two or more.

Further, as the other monomer, an aliphatic ring-containing (meth) acrylate such as a cyclohexyl group (meth)acrylate or an aromatic ring such as phenyl (meth)acrylate may be mentioned. (Meth) acrylate, non-crosslinkable acrylamide such as acrylamide or methacrylamide, N,N-dimethylaminoethyl (meth)acrylate, N,N (meth)acrylate a non-crosslinkable tertiary amino group such as dimethylaminopropyl ester (Meth) acrylate, vinyl acetate, styrene, and the like. These may be used alone or in combination of two or more.

Further, the monomer having a reactive functional group (a1) used in the first (meth) acrylate polymer (A) and the reactive functional group used in the second (meth) acrylate polymer (B) ( The selection of the monomer of b1) and the monomer containing the reactive functional group (b2) is determined by the reactivity with the crosslinking agent (C) used. The details are as follows.

Here, the second (meth) acrylate polymer (B) preferably contains a monomer having the above reactive functional group (b1) in an amount of more than 1% by mass, and the upper limit thereof is 50% by mass. The monomer containing the above reactive functional group (b1) is preferably 5 to 30% by mass, particularly preferably 10 to 20% by mass, more preferably 12 to 18% by mass. When the monomer containing the reactive functional group (b1) is in the above range, the degree of crosslinking of the second (meth) acrylate polymer (B) can be improved, and the first (methyl group) In the combination of the acrylate polymer (A), the obtained adhesive has a large elongation at break, and at the same time, the adhesive tends to have a predetermined gel ratio. As a result, the adhesive durability and the stress relaxation rate become excellent. In addition, when the content of the monomer containing the reactive functional group (b1) is 1% by mass or less, the crosslinking of the second (meth) acrylate polymer (B) is insufficient, and the gel ratio is specified. Below the value, the resulting durability can be lowered. On the other hand, when the content of the monomer containing the reactive functional group (b1) is 50% by mass or more, the crosslinking of the second (meth) acrylate polymer (B) may be excessive, and the elongation at break may be In small cases, durability will deteriorate. And if it contains The content of the monomer of the reactive functional group (b1) is limited to 30% by mass, and the obtained adhesive sheet is excellent in light leakage resistance.

In the polymer (B) of the above (1), the "substantial functional group is only (b1)", and the content of the other functional group reactive with the crosslinking agent (C) is not impeded by the functional group (b1). The degree of reactivity with the crosslinking agent (C) is permissible (in this case, the polymer (B) of (1) and the polymer (B) of (2) are repeated). In other words, the second (meth) acrylate polymer (B) is particularly preferably a functional group (b2) which does not contain a reactivity with the crosslinking agent (C) which is lower than the functional group (b1). Monomer (monomer containing reactive functional group (b2)). However, when the monomer having the reactive functional group (b2) as a constituent component is used, the mass ratio is preferably 1/5 or less, particularly 1/10 or less, of the content of the monomer containing the group (b1). The amount is preferred.

The second (meth) acrylate polymer (B), such as a monomer having a reactive functional group (b2), has a mass ratio exceeding 1/5 of the content of the monomer containing the reactive functional group (b1). At the time, the durability of the obtained adhesive layer may become low. If the reactive functional group (b2) in the second (meth) acrylate polymer (B) is excessive, the three-dimensional network structure formed thereby also has a large amount of reactive functional groups (b2) remaining, whereby It is presumed that the compatibility between the three-dimensional network structure and the first (meth) acrylate polymer (A) changes. As a result, the Haze value is likely to rise. Further, the reactive functional group (b2) has a large amount of the remaining three-dimensional network structure, and the mobility of the first (meth) acrylate polymer (A) inserted into the three-dimensional network structure is excessively restricted. Its knot As a result, the obtained stretched adhesive has a small elongation at break and the durability is deteriorated.

Further, when the adhesive composition of the present embodiment contains a decane coupling agent (D), the decane coupling agent (D) and the reactive functional group of the first (meth) acrylate polymer (A) (a1) (In particular, a carboxyl group) is reacted with a high molecular weight first (meth) acrylate polymer (A), and the obtained adhesive is excellent in adhesion to a glass substrate to be bonded, and the like (2) When the methyl group acrylate polymer (B) is excessively ruthenium containing a monomer having a reactive functional group (b2), the alkoxymethyl sulfonyl group of the decane coupling agent (D), etc., and the second (meth) group The reactive functional group (b2) (particularly a carboxyl group) of the acrylate polymer (B) is reacted, and is also bonded to the low molecular weight second (meth) acrylate polymer (B). As a result, the adhesion between the obtained adhesive and the adherend glass substrate or the like is deteriorated, and the durability of the adhesive layer is lowered.

Here, the alkyl (meth)acrylate having an alkyl group having 1 to 20 carbon atoms is polymerized with a crosslinking agent (C) and a reactive functional group to obtain a second (meth)acrylic acid. Ester polymer (B). The polymerization method is also a random copolymer, and a block copolymer can also be used.

In the present embodiment, the above-mentioned second (meth) acrylate-based polymer (B) may be used singly or in combination of two or more kinds.

The weight average molecular weight of the second (meth) acrylate polymer (B) is from 8,000 to 300,000, preferably from 10,000 to 200,000, particularly preferably from 50,000 to 100,000. That is, the second (meth) acrylate polymer (B), It is a low molecular weight polymer. Further, the weight average molecular weight in the present specification is a value in terms of polystyrene measured by a gel permeation chromatography (GPC) method.

When the weight average molecular weight of the second (meth) acrylate polymer (B) is in the above range, the three-dimensional network structure peculiar to the adhesive composition of the present embodiment can be formed, and it is effective for an excellent stress relaxation rate. That is, the weight average molecular weight of the second (meth) acrylate polymer (B) was less than 8,000, and a good three-dimensional network structure could not be obtained. On the other hand, the weight average molecular weight of the second (meth) acrylate polymer (B) is more than 300,000, the compatibility is low, and the polymer in the three-dimensional network structure formed by the polymer (B) (A) The insertion is not sufficient, and the gel ratio may be lower than the prescribed range. As a result, the durability and reusability of the obtained adhesive are deteriorated.

The first (meth) acrylate polymer (A) preferably contains, as a constituent component, a monomer having a functional group reactive with the crosslinking agent (C) or contains a second (meth)acrylic acid. The functional group (b1) constituting the monomer of the ester polymer (B) and the functional group (a1) having low reactivity with the crosslinking agent (C) contained as a constituent component, and particularly preferably, as a constituent component A monomer having a functional group having higher reactivity than the functional group (b1) and the crosslinking agent (C) is contained.

The first (meth) acrylate polymer (A) may not contain a monomer having a functional group reactive with the crosslinking agent (C). However, the monomer having a lower reactive functional group (a1) having reactivity with the reactive functional group (b1) of the second (meth) acrylate polymer (B) (containing the opposite The functional group (a1) contains a monomer, and is preferred. In the above polymer (A), if the reactive functional group (a1) is contained, the reaction of the second (meth) acrylate polymer (B) and the crosslinking agent (C) can be promoted, or a decane coupling agent ( D) When used, the reactive functional group (a1) of the first (meth) acrylate polymer (A) is reacted with the decane coupling agent (D) to obtain a glass surface of a liquid crystal cell or the like of the adhesive. The adhesion durability can be further high and there are better occasions.

When the first (meth) acrylate polymer (A) contains a monomer having the above reactive functional group (a1), the content thereof is usually 20% by mass or less, preferably 15% by mass or less, and preferably 10% by mass. The following is especially good. When the content of the monomer having a reactive functional group (a1) is more than 20% by mass, the glass transition temperature (Tg) of the first (meth) acrylate polymer (A) is too high, and the obtained adhesive is The required stress relaxation rate may not be available. Further, the content of the monomer containing the reactive functional group (a1) is preferably 15% by mass or less from the viewpoint of recyclability of the adhesive.

Further, in comparison with the monomer having a reactive functional group (b1) contained in the second (meth) acrylate polymer (B), the first (meth) acrylate polymer (A) has The ratio of the reactive functional group (a1) monomer in the first (meth) acrylate polymer (A) is more reactive than that contained in the second (meth) acrylate polymer (B) The ratio of the monomer of the functional group (b1) in the second (meth) acrylate polymer (B) is preferably small. Thereby, the first (meth) acrylate polymer (A) suppresses the reactive functional group (a1) contained therein. The reaction with the crosslinking agent (C) and the reactive functional group (b1) and the crosslinking agent (C) contained in the second (meth) acrylate polymer (B) can be reliably reacted. Thus, an adhesive having a tensile elongation at break of 1500% or more during stretching can be obtained.

The first (meth) acrylate polymer (A) does not contain a reactive functional group which is a second (meth) acrylate polymer (B) having reactivity with the crosslinking agent (C) in the molecule ( B1) The functional group of the same or more is preferable, and if it is present, the content of the monomer of the functional group in the molecule is preferably 1% by mass or less in the polymer (A), and is preferably 0. 5 mass% or less is particularly preferable. When the content of the monomer is more than 1% by mass, the reaction of the second (meth) acrylate polymer (B) and the crosslinking agent (C) which should be preferentially carried out may be inhibited.

Here, the polymerization method of the first (meth) acrylate polymer (A) obtained by polymerizing a (meth)acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms and a reactive functional group-containing monomer Random copolymers are also available, and block copolymers are also possible.

In the present embodiment, the first (meth) acrylate polymer (A) may be used singly or in combination of two or more kinds.

The weight average molecular weight of the first (meth) acrylate polymer (A) is from 500,000 to 3,000,000, preferably from 700,000 to 2,500,000, particularly preferably from 1,000,000 to 2,000,000. That is, the first (meth) acrylate polymer (A) is a high molecular weight polymer.

For example, the weight average of the (1) (meth) acrylate polymer (A) When the amount is in the above range, the first (meth) acrylate polymer (B) having the three-dimensional network structure formed by the second (meth) acrylate polymer (B) can be inserted well. The polymer (A) has a pseudo-crosslinked structure in which two or more molecules are inserted, and the polymer (A) is restrained with a certain degree of freedom. Further, the polymer (A) has relatively large molecules as described above, and the molecular chain has a high degree of freedom in maintaining a pseudo-crosslinked state of the three-dimensional network structure formed of the polymer (B). Thus, the formed adhesive has a predetermined gel ratio while having a large degree of elongation at break. As a result, the adhesive has an appropriate cohesive force and an excellent stress relaxation rate, whereby the adhesive is excellent in light leakage resistance, and has sufficient adhesive durability under high temperature conditions, such as lifting and peeling. Can be prevented.

Here, if the weight average molecular weight of the first (meth) acrylate polymer (A) is 500,000 or less, the cohesive force of the obtained adhesive becomes low, and durability and reusability may be deteriorated. . In addition, when the weight average molecular weight of the first (meth) acrylate polymer (A) is more than 3,000,000, the compatibility with the second (meth) acrylate polymer (B) or the like is deteriorated, and Haze (Haze) The value rises and it is difficult to obtain the required stress relaxation rate.

The ratio of the second (meth) acrylate polymer (B) to the first (meth) acrylate polymer (A) is preferably 5 to 50 parts by mass, and 5 to 40 parts by mass. Particularly preferred, 10 to 30 parts by mass is more preferred.

From the above ratio, from the first (meth) acrylate polymer (A) In the adhesive obtained by the adhesive composition of the second (meth) acrylate polymer (B), the second (meth) acrylate polymer (B) (low molecular weight polymer) is permeated through the crosslinking agent (C). a three-dimensional network structure is formed, and for the three-dimensional network structure, the first (meth) acrylate polymer (A) (high molecular weight polymer) is inserted in two or more molecules, and the polymer (A) has some kind of A pseudo-crosslinked structure that is constrained in a state of degree of freedom is formed. Thus, the obtained adhesive has a predetermined gel ratio while having a large degree of elongation at break. As a result, the adhesive has a suitable cohesive force and an excellent stress relaxation rate. Thereby, the obtained adhesive is excellent in durability and light leakage resistance.

The crosslinking agent (C) is preferably an isocyanate crosslinking agent, an epoxy crosslinking agent, an aziridine crosslinking agent, or a metal chelate crosslinking agent.

The isocyanate crosslinking agent contains at least a polyisocyanate compound. The polyisocyanate compound may, for example, be an aromatic polyisocyanate such as benzylidene diisocyanate, diphenylmethyl diisocyanate or p-xylylene diisocyanate; or an aliphatic polyisocyanate such as cyclohexylene diisocyanate; Ketone diisocyanate; ester ring polyisocyanate such as hydrogenated diphenylmethyl diisocyanate; and the biuret and isocyanurate. Further, a reactant addition product of a low molecular weight active hydrogen group such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane or castor oil can be exemplified.

As the epoxy-based crosslinking agent, for example, 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl m-pair Xylylene diamine, ethylene glycol diglycidyl Ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidylaniline, diglycidylamine, and the like.

As the aziridine-based crosslinking agent, diphenylmethyl-4,4'-bis(1-azabicyclopropanecarboxamide), trimethylolpropane tri-β-azepine propionic acid can be exemplified. Ester, tetramethylol methane tri-β-azepine propionate, toluene 2,4-bis(1-azabicyclopropanecarboxamide), triethylene melamine, bisisoisophthalide 1 -(2-methylaziridine), tri-1-(2-methylaziridine)phosphine, and trimethylolpropane tri-β-(2-methylaziridine)propionate .

Among the metal chelate crosslinking agents, a metal compound is a chelate compound of aluminum, zirconium, titanium, zinc, iron, tin or the like, and an aluminum chelate compound is preferred from the viewpoint of performance. As the aluminum chelate compound, diisopropoxy aluminum monooleyl acetoacetate, monoisopropoxy aluminum dioleyl acetoacetate, and monoisopropoxy aluminum monooleic acid monoethyl acetoacetate can be exemplified. , aluminum diisopropoxide, monolaurin acetoacetate, diisopropoxy aluminum monostearyl acetoacetate, and diisopropoxy aluminum monoisostearyl acetoacetate.

The content of the crosslinking agent (C), and the crosslinking group (for example, isocyanate group) of the crosslinking agent (C) is a reactive functional group of the second (meth) acrylate polymer (B) (b1) The amount of (for example, a hydroxyl group) is usually 0.05 to 5 equivalents, preferably 0.1 to 3.5 equivalents, particularly preferably 0.3 to 1.0 equivalents. When the amount of the crosslinkable group is 0.05 equivalent or less, the gel ratio of the obtained adhesive is 30% or less, and sufficient cohesive force cannot be exhibited. Further, the amount of the crosslinkable group is 0.1 equivalent or more, particularly 0.3 equivalent or more, and the obtained adhesive is resistant. The longevity can be further improved. On the other hand, when the amount of the crosslinkable group is 3.5 equivalent or less, the adhesiveness of the obtained adhesive can be excellent. Further, the amount of the crosslinkable group is 1.0 equivalent or less, and the crosslinking agent (C) can be favored for the formation of the three-dimensional network structure of the polymer (B), and the crosslinking of the polymer (A) can be effective. Prevent (presumed). As a result, the obtained adhesive has a good stress relaxation rate.

Further, in the present embodiment, the crosslinking agent (C) may be a crosslinking agent of a type in which the reactivity of both the reactive functional group (b1) and the reactive functional group (a1) is the same. Various types are used together. From the viewpoint of easy control of the three-dimensional network structure formed of the second (meth) acrylate polymer (B), as with the isocyanate-based crosslinking agent, it is preferred to use a crosslinking agent.

Here, as a combination of the crosslinking agent (C) and the (meth) acrylate polymer (A) and (B) and the respective reactive functional group-containing monomers, the crosslinking agent (C) is an isocyanate. In the case of a cross-linking agent, the monomer containing the reactive functional group (a1) of the polymer (A) can be selected from a monomer having a carboxyl group, and the reactive functional group (b1) containing the polymer (B) The monomer may be selected from a monomer having a hydroxyl group or a monomer having an amino group.

On the other hand, when the crosslinking agent (C) is an epoxy crosslinking agent, an aziridine crosslinking agent or a metal chelate crosslinking agent, the reactive functional group containing the polymer (A) (a1) The monomer is a monomer having a hydroxyl group, and a monomer having a reactive functional group (b1) of the polymer (B), and a monomer having a carboxyl group is preferred.

From the viewpoint of the flexibility of the bond formed between the crosslinking agent (C) and the polymer (B) and the stability of the crosslinking reaction, further, the reactive group from the polymer (A) and the decane coupling agent (D) A suitable reaction is carried out, and the crosslinking agent (C) can use a reactive functional group (a1) containing the polymer (A) from the viewpoint of improving the cohesive force of the obtained adhesive. The monomer as the carboxyl group-containing monomer, the reactive functional group (b1) monomer containing the polymer (B) as the hydroxyl group-containing monomer, and particularly preferably the reactive functional group (b2)-free monomer is not used. body.

The adhesive composition of the present embodiment preferably further contains a decane coupling agent (D). When the first (meth) acrylate polymer (A) has a carboxyl group, the organic reactive group of the decane coupling agent (D) and the first (meth) are contained in the case where the decane coupling agent (D) is contained. The carboxyl group of the acrylate polymer (A) reacts, and on the other hand, the alkoxymethyl sulfonyl group of the decane coupling agent (D) acts on the surface of the adherend such as a glass substrate. Thus, for example, when a polarizing plate is bonded to a liquid crystal glass unit or the like, the adhesion between the adhesive and the liquid crystal glass unit is further improved.

As such a decane coupling agent (D), an organic ruthenium compound having at least one in-mole alkoxycarbenyl group is used, which has good compatibility with an adhesive component and is light transmissive, for example, substantially transparent. As well. The amount of the decane coupling agent (D) to be added is preferably 0.01 to 0.5 parts by mass, particularly preferably 0.05, based on 100 parts by mass of the first (meth) acrylate polymer (A). To 0.3 parts by mass.

Specific examples of the decane coupling agent (D) include vinyl trimethoxy decane, vinyl triethoxy decane, and methacryloxypropyl group. a terpene compound containing an unsaturated group such as trimethoxydecane; a 3-glycidoxypropyltrimethoxydecane, a 2-(3,4-epoxycyclohexyl)ethyltrimethoxydecane, or the like Anthracene compound having an epoxy structure; 3-aminopropyltrimethoxydecane, N-(2-aminoethyl)-3-aminopropyltrimethoxydecane, N-(2-aminoethyl)-3- An aminoguanidine-containing compound such as aminopropylmethyldimethoxydecane; 3-chloropropyltrimethoxydecane; 3-isocyanatepropyltriethoxydecane. These may be used alone or in combination of two or more.

In the above adhesive composition, various additives commonly used for acrylic adhesives, such as an adhesion-imparting agent, an oxidation inhibitor, an ultraviolet absorber, a photostabilizer, a softener, a filler, a antimony preventive agent, and a refractive index adjustment, are used as needed. Agents and the like can be added.

The above adhesive composition, the first (meth) acrylate polymer (A) and the second (meth) acrylate polymer (B) are mixed, and the crosslinking agent (C) can be added in any step. And manufacturing according to the desired decane coupling agent (D).

As a preferable specific example, the (meth) acrylate polymers (A) and (B) can be prepared by a usual radical polymerization method. For the polymerization of the (meth) acrylate polymers (A) and (B), a polymerization initiator, a solution polymerization method, or the like can be used as needed. The polymerization solvent may, for example, be ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane or methyl ethyl ketone, or may be used in combination of two or more kinds.

The polymerization initiator may, for example, be an azo compound or an organic peroxide, or may be used in combination of two or more kinds. As an azo compound, for example, 2, 2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-even Nitrogen bis(2,4-dimethylcarbonitrile), 2,2'-azobis(2,4-dimethyl 4-methoxy nitrile), dimethyl 2,2'-azobis (2 -methylpropionic acid), 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(2-hydroxymethylpropionitrile), 2,2'-azo double [2-(2-imidazolin-2-yl)propane] and the like.

The organic peroxide may, for example, be benzoyl peroxide, t-butyl peroxybenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate or din-peroxydicarbonate. Propyl ester, di(2-ethoxyethyl) peroxydicarbonate, t-butylperoxyneodecanoate, peroxyl t-butylate (t- Butylperoxypyvalate), (3,5,5-trimethylcyclopentanone (hexanovl)) peroxide, dipropionyl peroxide, diacetyl peroxide, and the like.

Next, the obtained solutions of the polymers (A) and (B) are mixed, and a diluted solvent is added. Thereafter, the crosslinking agent (C) and, if necessary, the decane coupling agent (D) are added and sufficiently mixed to obtain a solvent-dilutable adhesive composition (coating solution).

The dilute solvent used for diluting the adhesive composition into a coating solution may, for example, be an aliphatic hydrocarbon such as hexane, heptane or cyclohexane; an aromatic hydrocarbon such as toluene or xylene; dichloromethane or dichloroethane. Halogenated hydrocarbon such as alkane; alcohol such as methanol, ethanol, propanol, butanol or 1-methoxy-2-propanol; acetone, methyl ethyl ketone, 2-pentanone, isoflurane, cyclopentane Ketones such as ketones; acetic acid An ester such as ethyl ester or butyl acetate; a cellosolve solvent such as ethyl cellosolve;

The concentration ‧ viscosity of the coating solution thus prepared is not particularly limited as long as it is within the range of application, and is appropriately selected depending on the case. For example, the concentration diluted to the adhesive composition is 10 to 40% by mass. Further, when the coating solution is obtained, the addition of a diluent solvent or the like is not a requirement, and the adhesive composition may be added as long as the adhesive composition is a possible viscosity. In this case, the adhesive composition can directly become a coating solution.

The above-mentioned adhesive is obtained by crosslinking the above-mentioned adhesive composition. The crosslinking of the above adhesive composition can be heat treated. Further, such heat treatment may also serve as a volatilization drying treatment for a diluent solvent or the like of the adhesive composition.

In the case of heat treatment, the heating temperature is preferably from 50 to 150 ° C, particularly preferably from 70 to 120 ° C. In addition, the heating time is preferably from 30 seconds to 3 minutes, and from 50 seconds to 2 is particularly preferred. Further, after the heat treatment, it is particularly preferable to set the ripening period at a normal temperature (for example, 23 ° C, 50% RH) for about 1 to 2 weeks.

The above heat treatment (and aging) is crosslinked by the second (meth) acrylate polymer (B) of the crosslinking agent (C) to form a dense three-dimensional network structure (presumed). Further, in the three-dimensional network structure, two or more molecules of the first (meth) acrylate polymer (A) are obtained without being directly accompanied by chemical bonds or with little chemical bond insertion, and the polymer (A) is restrained. Forming a pseudo-crosslinked structure. Further, when the first (meth) acrylate polymer (A) has a carboxyl group, the first (meth) acrylate is polymerized. The compound (A) reacts with the decane coupling agent (D), and the adhesion durability of the obtained adhesive to a glass substrate such as a liquid crystal cell can be improved.

The tensile elongation at break of the pressure-sensitive adhesive of the present embodiment is 1,500% or more, preferably 2,000% or more, and particularly preferably 2,500% or more. Further, the measurement of the degree of elongation at break is carried out for a separate adhesive layer without involving a substrate or the like. The adhesive obtained from the above material has a large degree of elongation at break, and the adhesive exhibits excellent stress relaxation rate, light leakage resistance, and durability.

The above-mentioned tensile test, specifically, an adhesive having a thickness of 500 μm, a width of 10 mm, and a length of 75 mm (in which the measurement range is 20 mm) was stretched at a rate of 200 mm/min in an environment of 23 ° C and 50% RH. .

Further, in the above-described tensile test, the adhesive of the present embodiment preferably has a stress of 1500% stretching of 0.1 to 15 N, preferably 0.3 to 10 N, and 0.5 to 2.5 N. For better. When the stress is 0.1 N or less, the cohesive force of the adhesive is insufficient, and the durability is deteriorated. On the other hand, when the stress exceeds 15 N, the stress relaxation rate of the adhesive is impaired, and the light leakage resistance may be deteriorated. Further, excessive aggregation may cause the adhesiveness to be lowered and the durability may be deteriorated.

Further, in the above-described tensile test of the adhesive of the present embodiment, the ratio of the stress at 1000% stretching, the stress at 1500% stretching, the stress at 2000% stretching, or the stretching at 25% is 0. .5 to 3.5 is preferred, and 0.8 to 2.5 is particularly preferred.

The gel ratio of the adhesive of the present embodiment is 30 to 90%. It is preferably from 40 to 80%, particularly preferably from 45 to 75%. If the gel ratio, that is, the degree of crosslinking, is within this range, the three-dimensional network structure formed by crosslinking of the second (meth) acrylate polymer (B) is good, and the light leakage resistance and durability of the adhesive are excellent. Both sides are fine. Further, the gel ratio of the adhesive is a value at the time of sticking (after the aging period). Specifically, the adhesive composition was applied onto a release sheet, and after heating, the gel ratio after storage for 7 days in an environment of 23° C. and 50% RH. The gel ratio of the adhesive, the value of which varies before the aging period passes. From such a viewpoint, whether or not the aging period has passed, and if it is unknown, the gel ratio may be changed to the above range after storage for 7 days in an environment of 23 ° C and 50% RH.

The adhesive described above is suitably used as an optical member, for example, adhesion of a polarizing plate and a phase difference plate, or adhesion of a polarizing plate (polarizing film) and a phase difference plate (phase difference film) to a glass substrate. The adhesive layer formed of the above-mentioned adhesive has a very excellent stress relaxation rate, and when the size of the adhesive body changes greatly, the stress generated by the dimensional change is absorbed by the adhesive and loosened, so that it is difficult to peel off from the adherend for a long time. At the same time, light leakage during use of the above optical components can be effectively prevented. That is, the adhesive of the present embodiment can be achieved both in light leakage resistance and durability when the optical member is used.

[adhesive sheet]

As shown in Fig. 1, the adhesive sheet 1A of the first embodiment is a release sheet 12 in this order from the bottom to the top, an adhesive layer 11 laminated on the release surface of the release sheet 12, and a substrate 13 laminated with the adhesive layer 11. Come to form.

Further, as shown in Fig. 2, the adhesive sheet 1B of the second embodiment has two release sheets 12a and 12b, and the two release sheets 12a and 12b hold the adhesive layer 11, whereby the adhesive layer 11 is used. The peeling surfaces of the peeling sheets 12a and 12b are in contact with each other. In addition, the peeling surface of the peeling sheet in this specification is the surface which has the peeling property in the peeling sheet, the surface which carried out the peeling process, and the peeling process were not implemented, and the surface which shows the peeling property is also included.

In each of the adhesive sheets 1A and 1B, the adhesive layer 11 is composed of an adhesive obtained by crosslinking the above-mentioned adhesive composition.

The thickness of the adhesive layer 11 is appropriately determined depending on the purpose of use of the adhesive sheets 1A, 1B, and is usually in the range of 5 to 100 μm, preferably 10 to 60 μm, for example, an optical member, particularly an adhesive layer for a polarizing plate. In the case of 10 to 50 μm, 10 to 30 μm is particularly preferable.

The substrate 13 is not particularly limited, and any of the substrates used as the adhesive sheet of the adhesive sheet can be used. For example, in addition to optical components, woven fabrics or nonwoven fabrics of fibers such as rayon, acrylic, and polyester; papers of upper quality paper, laminated paper, impregnated paper, coated paper, etc.; metal foils of aluminum, copper, etc. ; urethane foam; foam of polyethylene foam; etc.; polyester film of polyethylene terephthalate; polybutylene terephthalate; polyethylene naphthalate ; cellulose film such as triacetyl cellulose; polyurethane film; polyethylene film; polypropylene film; polyvinyl chloride film; polychloroethylene vinyl film; polyvinyl alcohol film; ethylene vinyl acetate copolymer film Polystyrene film; polycarbonate film; acrylic tree A lipid film; a polysilene resin film; a plastic film such as a cycloolefin resin film. Two or more kinds of these layers and the like. Plastic film, one-axis rolling or biaxial pressure extension is also acceptable.

As the optical member, for example, a polarizing plate (polarized light film), a polarizer, a phase difference plate (phase difference film), a viewing angle compensation film, a brightness enhancement film, a color contrast film, a liquid crystal polymer film, and the like. Among them, a polarizing plate (polarized light film) is easily contracted and has a large dimensional change, and is suitable as an object of the adhesive (the above-mentioned adhesive layer 11) of the present embodiment from the viewpoint of light leakage resistance.

The thickness of the substrate 13 varies depending on the type thereof, for example, in the case of an optical member, usually 10 μm to 500 μm, preferably 50 μm to 300 μm.

As the release sheets 12, 12a, 12b, for example, a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, a chloroethylene copolymer, or the like can be used. Film, polyethylene terephthalate film, polyethylene naphthalate film, polybutylene terephthalate film, polyurethane film, ethylene vinyl acetate film, ionomer resin film, vinyl (meth)acrylic copolymer film, ethylene ‧ (meth) acrylate copolymer film, polystyrene film, polycarbonate film, polyimide film, fluororesin film, and the like. In addition, these crosslinked films are also available. Further, these laminated films are also available.

In the peeling surface of the release sheet (particularly, the surface to be bonded to the adhesive layer 11), it is preferred to carry out a release treatment. The stripper used in the stripping process, For example, a stripper for alkyds, decanes, fluorines, unsaturated polyesters, polyolefins, and waxes.

The thickness of the release sheets 12, 12a, 12b is not particularly limited and is usually about 20 to 150 μm.

In the production of the pressure-sensitive adhesive sheet 1A, the adhesive sheet solution (coating solution) is applied to the release surface of the release sheet 12, and heat treatment is performed. After the pressure-sensitive adhesive layer 11 is formed, the substrate is applied to the pressure-sensitive adhesive layer 11. 13 laminates. Thereafter, it is preferred to set the ripening period.

Further, the conditions of the heat treatment and the ripening are as described above.

Further, the pressure-sensitive adhesive sheet 1B is produced by applying a coating solution containing the above-mentioned adhesive composition on the peeling surface of one of the release sheets 12a (or 12b), and heat-treating the adhesive layer. The peeling surface of the other release sheet 12b (or 12a) is superposed on the adhesive layer 11.

The coating method of the coating solution can be, for example, a roll coating method, a knife coating method, a roll coating method, a knife coating method, a pressure coating method, a gravure coating method, or the like.

Here, for example, a liquid crystal display device comprising a liquid crystal cell and a polarizing plate is used, and a polarizing plate is used as the base material 13 of the adhesive sheet 1A, and the release sheet 12 of the adhesive sheet 1A is peeled off, and the exposed adhesive layer 11 and liquid crystal are exposed. Units and fits.

Further, for example, when a liquid crystal display device in which a phase difference plate is disposed is manufactured 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 and adhered. The exposed adhesive layer 11 of the sheet 1B is bonded to the phase difference plate. Next, the release 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 of the adhesive sheet 1A is bonded to the phase difference plate. Further, the other release sheet 12b (or 12a) is peeled off from the adhesive layer 11 of the above-mentioned adhesive sheet 1B, and the exposed adhesive layer 11 of the adhesive sheet 1B is bonded to the liquid crystal cell.

According to the above adhesive sheets 1A, 1B, the adhesive layer 11 is excellent in stress relaxation rate. For example, when adhesion of a polarizing plate is applied, stress generated by deformation of the polarizing plate is absorbed by the adhesive layer 11 and loosened. Excellent light leakage resistance and high durability.

The above description is for easier understanding of the present invention, and the present invention is not limited thereto. Therefore, each element disclosed in the above embodiments includes all design changes and equivalents of the scope of the technology of the present invention.

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

[Example]

Hereinafter, the present invention will be further specifically described by way of examples, and the present invention is not limited thereto.

[Example 1]

1. Modulation of polymer (A)

Adding n-butyl acrylate 97.0 to a reaction vessel with a stirrer, thermometer, reflow cooler, dropping device and nitrogen inlet tube The mass fraction was 3.0 parts by mass of acrylic acid, 200 parts by mass of ethyl acetate, and 0.08 parts by mass of 2,2'-azobisisobutyronitrile, and the air in the reaction vessel was replaced with nitrogen. The mixture was stirred under a nitrogen atmosphere, and the reaction solution was heated to 60 ° C, and after 16 hours of reaction, it was cooled to room temperature. Here, a part of the obtained solution was subjected to GPC measurement by the following method, and the formation of the polymer (A) having a weight average molecular weight of 1.5 million was confirmed.

2. Modulation of polymer (B)

In a reaction vessel having a stirrer, a thermometer, a reflux cooler, a dropping device, and a nitrogen introduction tube, 85.0 parts by mass of n-butyl acrylate, 15.0 parts by mass of 2-hydroxyethyl acrylate, and ethyl acetate were added. 200 parts by mass of the ester, 0.16 parts by mass of 2,2'-azobisisobutyronitrile, and 0.3 parts by mass of 2-mercaptoethanol, the air in the reaction vessel was replaced with nitrogen. While stirring in this nitrogen atmosphere, the reaction solution was heated to 70 ° C, and after 6 hours of reaction, it was cooled to room temperature. Here, a part of the obtained solution was subjected to GPC measurement by the following method, and the formation of the polymer (B) having a weight average molecular weight of 60,000 was confirmed.

3. Modulation of adhesive composition

100 parts by mass (solid content converted value) of the polymer (A) obtained in the above step (1) and 15 parts by mass (solid content converted value) of the polymer (B) obtained in the above step (2) are mixed and used as cross-linking. (C), a benzylidene diisocyanate (TDI-based) adduct of trimethylolpropane in an amount equivalent to 0.6 equivalents of the hydroxyl group of the polymer (B) (manufactured by Nippon Polyurethane Co., Ltd., trade name "( CORONATE) L") 2.21 parts by mass added. Finally, as a decane coupling agent (D), 3-epoxypropyl 0.2 parts by mass of oxypropyltrimethoxydecane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBM403") was added, and the mixture was thoroughly stirred to obtain a diluted solution of the adhesive composition.

Here, the composition of the adhesive composition is shown in Table 1. Further, the details of the abbreviations and the like described in Table 1 are as follows.

[Polymer (A) and (B)]

BA: n-butyl acrylate

AA: Acrylic

HEA: 2-hydroxyethyl acrylate

4HBA: 4-hydroxybutyl acrylate

[plasticizer]

‧ADEKASIZER-C-8: trimellitate plasticizer (tris(2-ethylhexyl) trimellitate) (made by Asahi Denki Kogyo Co., Ltd., trade name: ADEKASIZER-C-8)

[Crosslinking agent (C)]

‧Isocyanate crosslinker

CORONATE-L: a benzylidene diisocyanate adduct of trimethylolpropane (manufactured by Nippon Polyurethane Co., Ltd., trade name: CORONATE-L)

TAKENATE-D-110N: a xylene diisocyanate adduct of trimethylolpropane (manufactured by Mitsui Chemicals, Inc., trade name: TAKENATE-D-110N)

‧Epoxy crosslinking agent

TETRAD-X: N, N, N', N'-tetraglycidyl m-p-xylylenediamine (Mitsubishi Gas Chemical Co., Ltd., trade name "TETRAD-X")

[Hydrane coupling agent (D)]

KBM403: 3-glycidoxypropyltrimethoxydecane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KBM403)

KBE9007: 3-isocyanate propyl triethoxy decane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KBE9007)

A release sheet of a release sheet (SP-PET3811, thickness: 38 μm, manufactured by Linde Co., Ltd.) which was subjected to a release treatment with a phthalic oxide-based release agent on one side of a polyethylene terephthalate film, The diluted solution of the obtained adhesive composition was applied by a knife coater, and the coating was dried to a thickness of 25 μm after the film was dried, and heat treatment was performed at 90 ° C for 1 minute to form an adhesive layer.

Next, a polarizing film having a disk-shaped liquid crystal layer and a polarizing film integrated with the viewing angle-enhancing film are bonded together so that the adhesive layer and the disk-shaped liquid crystal layer are in contact with each other at 23 ° C. 50% RH was aged for 7 days to obtain a polarizing plate with an adhesive layer.

[Examples 2 to 13, Comparative Examples 1 to 5]

The types and ratios of the monomers constituting the adhesive composition, the types and addition amounts of the plasticizer, the crosslinking agent, and the decane coupling agent, and the composition ratios of the polymer (A) and the polymer (B) are listed in the table. 1. In addition to this change, the production of a polarizing plate with an adhesive layer was carried out in the same manner as in Example 1.

Here, the above weight average molecular weight (Mw) is infiltrated with a gel. Chromatography (GPC) was measured under the following conditions (GPC measurement) in terms of polystyrene-equivalent weight average molecular weight.

<Measurement conditions>

‧GPC measuring device: manufactured by Tosoh Co., Ltd., HLC-8020

‧GPC column (passed in the following order): made by Tosoh Co., Ltd.

TSK guard column HXL-H

TSK gel GMHXL (×2)

TSK gel G2000HXL

‧ Determination of solvent: tetrahydrofuran

‧Measurement temperature: 40 ° C

[Experimental Example 1] (Measurement of gel ratio)

In the examples or comparative examples, the polarizing plate used in the production of the polarizing plate with the adhesive layer is replaced, and one side of the polyethylene terephthalate film is peeled off with a decane-based stripping agent. A release sheet (manufactured by Linde Co., Ltd., SP-PET3801, thickness: 38 μm) was used to prepare an adhesive sheet. Specifically, on the adhesive layer in which the constituent body composed of the release sheet/adhesive layer (thickness: 25 μm) obtained in the production process of the example or the comparative example is exposed, the release sheet is stacked to make an adhesive layer. It is in contact with the side of the peeling treatment surface. Thereby, an adhesive sheet of a release sheet/adhesive layer/release sheet is formed.

The obtained adhesive sheet was aged at 23 ° C, 50% RH for 7 days. Thereafter, the adhesive sheet is made into a size of 80 mm × 80 mm. As such, the adhesive layer is covered with a mesh made of polyester (net size 200), and the quality of the adhesive is weighed with a precision balance. The mass at this time is taken as M1.

Next, the adhesive of the above-mentioned polyester net bag was immersed in ethyl acetate at room temperature (23 ° C) for 24 hours. Thereafter, the adhesive was taken out, the temperature was 23 ° C, and the relative humidity was 50%, air-dried for 24 hours, and further dried in an oven at 80 ° C for 12 hours. The quality of the dried adhesive is weighed with a precision balance. The mass at this time is taken as M2. The gel ratio (%) is represented by (M2/M1) × 100. The results are shown in Table 2.

[Experimental Example 2] (Measurement of optical properties)

As the measurement sample, an adhesive sheet for use in the measurement of the gel ratio and the same adhesive sheet were prepared (completed in 7 days). The adhesive layer of the adhesive sheet was measured using a Haze instrument (NDH2000, manufactured by Nippon Denshoku Industries Co., Ltd.), and a Haze value (%) was measured in accordance with JIS K7105 (some cases are slightly Hz (%)). ). The results are shown in Table 2. Also, a preferred Haze value ranges from 0 to 5%.

[Experimental Example 3] (Durability Evaluation)

The polarizing plate with an adhesive layer obtained in the example or the comparative example was adjusted to a size of 233 mm × 309 mm by a cutting device (Super Knife manufactured by Takino Seisakusho Co., Ltd., PN1-600). The release sheet was peeled off, and the exposed adhesive was adhered to the flawless glass (manufactured by Corning Co., Ltd., Eagle XG), and then pressurized at 0.5 MPa, 50 ° C for 20 minutes in an autoclave manufactured by Kurihara Seisakusho Co., Ltd. .

Thereafter, the mixture was placed in an environment of durable conditions of drying at 80 ° C, and observed with a magnifying glass of 10 times after 500 hours. Appearance changes with the following Benchmark. The results are shown in Table 2.

◎: 4 sides, no problem

○: No problem in the 4 sides from the outer peripheral end of 0.6 mm or more

In the case where at least one of the four sides is at least 0.6 mm from the outer peripheral end portion, there is a problem that the appearance of the adhesive of 0.1 mm or more, such as floating, peeling, foaming, and streaking, is abnormal.

[Experimental Example 4] (Light leakage resistance test)

The polarizing plate with an adhesive layer obtained in the example or the comparative example was adjusted to a size of 233 mm × 309 mm by a cutting device (Super Knife manufactured by Takino Seisakusho Co., Ltd., PN1-600). The release sheet was peeled off, and the exposed adhesive layer was adhered to an aluminum-free glass (Eagle XG, manufactured by Corning Co., Ltd.), and then an oven made by Kurihara Co., Ltd. was pressed at 0.5 MPa and 50 ° C for 20 minutes. Further, in the above-mentioned bonding, in the surface of the glassless glass, the polarizing plate with the adhesive layer was carried out with the polarization axis in the Nicols cross state (polarizing axis: ∠45°, ∠135°). In this state, it was placed in a dry environment at 80 ° C for 250 hours, and then placed in an environment of 23 ° C and 50% RH for 2 hours. This was used as a sample, and the light leakage property was evaluated by the method shown below. The results are shown in Table 2.

<Light leakage evaluation: △L*>

Using the MCPD-2000 manufactured by Otsuka Electronics Co., Ltd., the brightness L* of each field shown in Fig. 3 in the above sample was measured, and the brightness difference ΔL* was used, and the formula ΔL*=[(b+c) was used. +d+e)/4]-a (However, a, b, c, d, and e are solved for the lightness in the A field, the B field, the C field, the D field, and the predetermined measurement point (one place in the central part of each field) in the E field, As light leakage. The smaller the value of ΔL*, the less light leakage. Also, L*max represents the maximum brightness in all of the above fields.

<Light leakage evaluation: visual inspection>

The above sample was placed on a flat panel illumination lamp (HF-SL-A312LC, illuminance: 26,000 Lux, brightness: 10,000 cd), and a two-dimensional color luminance meter (Konica Minolta) was used. Co., Ltd., CA-2000) was used to perform image conversion of brightness distribution using analysis software (CA-S20w, manufactured by Konica Minolta Co., Ltd.). The luminance distribution image of the obtained sample was evaluated based on the evaluation criteria shown in FIG.

[Experimental Example 5] (tensile experiment)

A peeling-treated sheet of a release sheet (SP-PET3811, manufactured by Linde Co., Ltd.) which was subjected to a release treatment with a phthalic acid-based release agent on one side of a polyethylene terephthalate film was exemplified and comparatively The prepared adhesive composition was applied so that the coating thickness after drying was 25 μm, and heating was performed at 100 ° C for 1 minute, and an adhesive layer was formed. Peeling of the other release sheet (SP-PET3801, manufactured by Linde Co., Ltd.) in which the adhesive layer and one side of the polyethylene terephthalate film were peeled off with a decane-based release agent The treated surface is bonded to obtain an adhesive sheet.

Laminating the above adhesive layer in multiple layers to make the adhesive in the adhesive sheet The total thickness of the layers was 500 μm, and only the peeling sheet of the outermost layer of the laminate was left, and it was left at 2° C. under an atmosphere of 50° RH at 23° C. for 2 weeks. Thereafter, a multi-layered adhesive sheet was laminated from the above-mentioned adhesive layer, and a sample having a length of 10 mm × 75 mm was cut out, and the peeling sheet of the outermost layer of the laminated body was peeled off, and the sample was loaded to have a measurement range of 10 mm wide by 20 mm long. In a 23 ° C, 50% RH environment, a tensile tester (tensilon, manufactured by Ori Co., Ltd.) was used to stretch at a stretching speed of 200 mm/min, and when 1000% was stretched, 1500% was stretched, 2000. Stress (N) and maximum stress at % stretch and 2500% stretch. Further, the ratio of the stress at the time of 1000% stretching, the 1500% stretching, the 2000% stretching, or the 2500% stretching stress was calculated. The results are shown in Table 2.

As can be seen from Table 2, in the polarizing plate with an adhesive layer obtained in the examples, the adhesive had a tensile elongation at break of 1500% or more, and was excellent in durability and light leakage resistance. On the other hand, in the polarizing plate with an adhesive layer obtained in the comparative example, the elongation at break of the adhesive was 1500% or less, and both of the durability and the light leakage resistance were not good.

The adhesive of the present invention is suitable for adhesion of an optical member such as a polarizing plate and a phase difference plate, and the adhesive sheet of the present invention is suitably used as an adhesive sheet for an optical member such as a polarizing plate or a phase difference plate.

1A, 1B‧‧‧Adhesive tablets

11‧‧‧Adhesive layer

12,12a,12b‧‧‧ peeling film

13‧‧‧Substrate

Fig. 1 is a cross-sectional view showing an adhesive sheet according to a first embodiment of the present invention.

Fig. 2 is a cross-sectional view showing an adhesive sheet according to a second embodiment of the present invention.

Fig. 3 is a view showing the field of experimental measurement of light leakage resistance in a polarizing plate having an adhesive layer.

Fig. 4 is a view showing the evaluation criteria of the light leakage resistance test (visual) in the polarizing plate with the adhesive layer.

1A‧‧‧Adhesive tablets

11‧‧‧Adhesive layer

12‧‧‧ peeling film

13‧‧‧Substrate

Claims (7)

An adhesive comprising: a first (meth) acrylate polymer (A) having a weight average molecular weight of 500,000 to 3,000,000, and a second (meth)acrylic acid having a weight average molecular weight of 8,000 to 300,000 The component obtained by crosslinking the ester polymer (B) has a tensile elongation at break of 1500% or more and a gel ratio of 30 to 90% in a tensile test. The adhesive of claim 1, wherein the ratio of the second (meth) acrylate polymer (B) is 5 to 100 parts by mass of the first (meth) acrylate polymer (A). 50 parts by mass. The adhesive according to claim 1, wherein the second (meth) acrylate polymer (B) before crosslinking is a constituent component, and includes more than 1% by mass and 50% by mass of less than reactive. A monomer of a functional group. An adhesive according to claim 3, wherein the second (meth) acrylate polymer (B) is permeable to a crosslinking agent (C) having a crosslinkable group reactive with the above reactive functional group. , being cross-linked. An adhesive sheet having a substrate and an adhesive layer, wherein the adhesive layer is formed of the adhesive of any one of claims 1 to 4. The adhesive sheet of claim 5, wherein the substrate is an optical component. An adhesive sheet comprising: 2 peeling sheets, The adhesive layer held by the release sheet is brought into contact with the release surface of the two release sheets, and the adhesive layer is an adhesive of any one of claims 1 to 4. Formed.