TWI527870B - Adhesive and adhesive tape - Google Patents

Description

Adhesive and adhesive sheet

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

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

As a method of preventing this problem, for example, (1) adhesion will be applied A method in which an adhesive layer having excellent form stability is adhered to an optical member such as a polarizing plate to suppress the optical member itself, or (2) an adhesive layer having a small stress during shrinkage using the optical member is used. Methods. 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 rate 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. As a result, 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, whereby the resulting adhesive is obtained. The composition is moderately soft, and the stress relaxation rate is imparted to the adhesive layer, whereby light leakage resistance and durability are desired.

[Patent Document 1] Japanese Laid-Open Patent Publication No. Hei No. Hei. No. Hei. No. Hei. No. Hei. No. Hei.

However, the formation of an adhesive layer of a plasticizer or a fluid paraffin adhesive composition has the difficulty of bleeding out of the plasticizer and the flowing paraffin over time. Further, as a result, the adhesive durability is lowered, and the liquid crystal cell of the adherend is contaminated, and the like, which is a concern of the present. In addition, Tim When the adhesive composition of the urethane elastomer is intended to maintain compatibility, the upper limit of the amount of addition of the urethane elastomer is limited, and the improvement in the stress relaxation rate tends to be insufficient. Further, in order to increase the high stress relaxation rate, the amount of addition of the urethane elastomer is increased, and the compatibility with the acrylic pressure-sensitive adhesive is lowered, and problems such as white turbidity occur. As described above, in the prior art, it is difficult for the optical member 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 first aspect of the present invention provides an adhesive characterized in that the maximum stress is a stress at the time of fracture or 4,000% elongation at the time of stretching (Invention 1).

In the adhesive of the above invention (Invention 1), stress relaxation is possible when the adhesive is greatly stretched, and the conventional adhesive does not have such a property. When the adhesive having such an excellent stress relaxation rate is 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 (meth)acrylate polymer having a weight average molecular weight of 500,000 to 3,000,000 is preferably contained in an amount of 50% by mass or more and a gel ratio of 30 to 90% (Invention 2).

In the above invention (Invention 1, 2), the first (meth) acrylate polymer (A) having a weight average molecular weight of 500,000 to 3,000,000 and the second (methyl) having a weight average molecular weight of 8,000 to 300,000 are contained. Acrylate polymerization The component (B) is crosslinked to form a component, and the ratio of the second (meth) acrylate polymer (B) to the first (meth) acrylate polymer (A) is 5 to 50. Parts by mass (Invention 3).

In the above invention (Invention 3), the second (meth) acrylate polymer (B) before crosslinking, as a constituent component, contains more than 1% by mass of a monomer having a reactive functional group, and 50% by mass Full (Invention 4).

Secondly, the present invention is an adhesive sheet having a substrate and an adhesive layer, and the above-mentioned adhesive layer is formed by 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 has two release sheets and an adhesive layer which is held by the release sheet, and is in contact with the release surface of the two release sheets, and the adhesive layer has the above-mentioned adhesive (Invention 1 to 4) Formation (Invention 7).

In the adhesive of the present invention, stress relaxation is also possible when the adhesive is greatly stretched, which is not the case with conventional adhesives. When the adhesive having such an excellent stress relaxation rate is used, when it is applied to an optical member such as a polarizing plate, an adhesive sheet excellent in both light leakage resistance and durability can be obtained. Further, by applying the pressure-sensitive adhesive sheet of the present invention, it is possible to obtain an optical member excellent in both light leakage resistance and durability.

Hereinafter, embodiments of the present invention will be described.

[adhesive]

The usual adhesive, stretching will cause the polymer in the adhesive to be taken sequentially The stress gradually rises to the maximum stress at the time of fracture. However, the adhesive of the present embodiment has a maximum stress ratio at the time of stretching, a stress at the time of fracture (in the case of 4000% tensile fracture) or a stress at 4000% stretching (when 4000% is not broken). That is, when the stress-deformation curve is drawn, there is a maximum stress point before the fracture, which is a property which the conventional adhesive does not have. It can be presumed that in the adhesive, the relaxation of the stress is generated while stretching. When the adhesive having such an excellent stress relaxation rate is applied to an optical member such as a polarizing plate, an adhesive sheet excellent in both light leakage resistance and durability can be obtained.

Specifically, in the adhesive of the present embodiment, an adhesive sheet having a width of 10 mm, a length of 20 mm, and a thickness of 500 μm is obtained by lamination, and the maximum stress is obtained when 4000% stretching is performed at a speed of 200 mm/min in a tensile test. It is larger than the stress at the time of fracture or 4000% stretching. Moreover, this stretching test was carried out without using a separate adhesive layer together with the substrate or the like.

Further, in the adhesive of the present embodiment, the maximum stress is preferably 10 N or less, and particularly preferably 5 N or less. The maximum stress is too large, and there is a case where the light leakage resistance is deteriorated. The lower limit of the maximum stress is preferably 0.1 N or more from the viewpoint of durability, and particularly preferably 0.5 N or more.

Further, in the adhesive of the present embodiment, the maximum stress is preferably 5% or more larger than the stress at the time of breaking or 4000% stretching, and more preferably 10% or more. It can be inferred that the larger the value, the faster the rate of stress relaxation, and the upper limit is not particularly limited, and is usually about 200%.

Further, in the adhesive of the present embodiment, it is preferable to stretch by 2000% or more and to stretch by 4,000% or more until the fracture is caused by the above-described conditions. Stretched to be especially good. Further, since the upper limit is not particularly limited, it is usually about 40,000%.

The adhesive having the above characteristics is preferably a (meth)acrylate polymer having a weight average molecular weight (Mw) of 500,000 to 3,000,000, 50% by mass or more, and a gel ratio of 30 to 90%. The first (meth) acrylate polymer (A) having a weight average molecular weight of 500,000 to 3,000,000 and the second (meth) acrylate polymer (B) having a weight average molecular weight of 8,000 to 300,000 The ratio of the component (1) of the first (meth) acrylate polymer (A) to the second (meth) acrylate polymer (B) is 5 to 50 parts by mass. 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-mentioned adhesive is preferably a first (meth) acrylate polymer (A) having a weight average molecular weight of 500,000 to 3,000,000, and a second (meth) having a weight average molecular weight of 8,000 to 300,000. The adhesive composition of the acrylate polymer (B) and the crosslinking agent (C) is particularly preferable, and further contains an adhesive composition of a decane coupling agent (D) and is obtained by crosslinking. In the above-mentioned adhesive, a low molecular weight polymer which has been conventionally used as a plasticizer is chemically crosslinked 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 each other to form a pseudo-crosslinked structure between the high molecular weight polymers. Thus, the obtained adhesive has a maximum stress at the time of stretching which is larger than the stress at the time of breaking or 4000% stretching. Its knot As a result, the adhesive can exert 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) reactive with the crosslinking agent (C) as a constituent component, and the polymer (B) The functional group reactive with the crosslinking agent (C) is substantially only the functional group (b1), and (2) preferably has a reactivity with the crosslinking agent (C) as a functional group satisfying the following formula (I) ( The monomer of b1) and the monomer having the functional group (b2) satisfying the reactivity of the crosslinking agent (C) satisfying the following formula (I) are preferably used as a constituent component.

Reactivity with crosslinker (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 an alkyl (meth) acrylate having an alkyl group having 1 to 20 carbon atoms and having a functional group reactive with the crosslinking agent (C). A monomer (a monomer containing a reactive functional group), and a copolymer of another monomer which can also be used as needed. Further, the first (meth) acrylate polymer (A) preferably further contains no monomer having a reaction with the reactive functional group as a constituent monomer.

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

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, 3-hydroxypropyl (meth)acrylate or (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 aminoethyl (meth)acrylate or n-butyl (meth)acrylate or the like. These may be used alone or in combination of two or more.

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

Further, the 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) are used. The selection of the monomer of (b1) and the monomer containing the reactive functional group (b2) is determined by the relationship between the reactivity of the monomer (b1) and the crosslinking agent (C) used. The details are as follows.

Here, the second (meth) acrylate polymer (B) is preferably a monomer containing the reactive functional group (b1), and is more than 1% by mass, and the upper limit is 50% by mass. Further preferably, the monomer containing the reactive functional group (b1) is 5 to 30% by mass, more preferably 10 to 20% by mass, still 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) is improved, and the first (meth) acrylate is used. The combination of the ester polymer (A) provides an excellent stress relaxation rate of the obtained adhesive. 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, which causes durability. Low sex The possibility. 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) is excessive, which causes The possibility that the fit to the adherend becomes lower. In addition, when the upper limit of the content of the monomer containing the reactive functional group (b1) is 30% by mass, the light leakage resistance of the obtained adhesive sheet is further improved.

In the polymer (B) of the above (1), the phrase "substantially only the functional group (b1)" means another functional group reactive with the crosslinking agent (C) as long as it does not impair the functional group (b1). The amount of reactivity with the crosslinking agent (C) and may be contained (in this case, the polymer (B) of (1) and the polymer (B) of (2) are repeated). However, the second (meth) acrylate polymer (B) does not contain a functional group (b2) having a lower reactivity than the functional group (b1) and the crosslinking agent (C) as a constituent monomer. A monomer (a monomer having a reactive functional group (b2)) is preferred. However, when a monomer having a reactive functional group (b2) is used as a constituent component, the mass ratio is 1/5 or less of the content of the monomer containing the reactive functional group (b1), and particularly 1/ An amount of 10 or less is preferred.

When the second (meth) acrylate polymer (B) contains a monomer having a reactive functional group (b2), the mass ratio is more than the content of the monomer containing the reactive functional group (b1). 1/5, the durability of the obtained adhesive layer was lowered. When the reactive functional group (b2) in the second (meth) acrylate polymer (B) is too large, it is estimated that there is a large amount of reactive functional group (b2) remaining in the three-dimensional network structure formed thereby. Compatibility of the three-dimensional network structure and the first (meth) acrylate polymer (A) It will change. As a result, there is a case where the Haze value rises. Further, it is also presumed that the reactive functional group (b2) is 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 limit. Thus, when the obtained adhesive is stretched, the maximum stress is not more than the stress at the time of breaking or 4000% stretching. As a result, durability may be 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) (particularly a carboxyl group) is bonded to the high molecular weight first (meth) acrylate polymer (A), and the adhesion between the obtained adhesive and the glass substrate of the adherend is changed. It is excellent, but, for example, the second (meth) acrylate polymer (B) is an alkoxycarbenyl group containing a monomer having a reactive functional group (b2) and a decane coupling agent (D). The reactive functional group (b2) (particularly a carboxyl group) of the second (meth) acrylate polymer (B) is also reacted to bond with the low molecular weight second (meth) acrylate polymer (B). Hehe. As a result, the adhesion of the obtained adhesive to 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 and a monomer having a functional group reactive with the crosslinking agent (C) are polymerized to obtain a second (meth) acrylate. The polymerized form of the polymer (B) may be a random copolymer or a block copolymer may 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. use.

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 20,000 to 150,000. That is, the second (meth) acrylate polymer (B) is a low molecular weight polymer component. 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 within the above range, in the adhesive composition of the present embodiment, a peculiar three-dimensional network structure can be formed, and when stretching is performed, Adhesives with a maximum stress greater than the stress at break or 4000% stretch contribute. That is, if the weight average molecular weight of the second (meth) acrylate polymer (B) is 8,000 or less, a good three-dimensional network structure cannot be obtained. On the other hand, if 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 into the polymer (B) The insertion of (A) is insufficient, and there is a possibility that an adhesive of the above characteristics cannot be obtained. As a result, durability and reusability are deteriorated.

The first (meth) acrylate polymer (A) preferably contains no monomer having a functional group reactive with the crosslinking agent (C) as a constituent component, or contains a second component as a constituent component. The functional group (b1) of the acrylate polymer (B) having a low reactivity with the crosslinking agent (C) is a monomer having a low functional group (a1), and particularly preferably, as a constituent component, does not contain A monomer having a functional group having higher reactivity with the crosslinking agent (C) than the functional group (b1).

The first (meth) acrylate polymer (A) may not contain a monomer having a functional group reactive with the crosslinking agent (C). However, it is a monomer containing a reactive functional group (a1) having a reactivity with the reactive functional group (b1) of the second (meth) acrylate polymer (B) (containing a reactive functional group ( There are also preferred occasions for the monomer of a1). If the reactive functional group (a1) in the above polymer (A) can promote the reaction of the second (meth) acrylate polymer (B) and the crosslinking agent (C), or the decane coupling agent (D) When it is used, the reactive functional group (a1) of the first (meth) acrylate polymer (A) reacts with the decane coupling agent (D) to obtain a glass such as a liquid crystal cell of the obtained adhesive. The adhesion durability of the surface is further improved, so there are preferable occasions.

When the first (meth) acrylate polymer (A) is a monomer containing the reactive functional group (a1), the content thereof is usually 20% by mass or less, preferably 15% by mass or less, and 10 is preferable. The mass % or less is particularly 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 it may be difficult to obtain When stretched, the maximum stress is greater than the stress at break or 4000% stretch. As a result, the resulting adhesive does not reach the required stress relaxation rate. In addition, the content of the monomer containing the reactive functional group (a1) is preferably 15% by mass or less from the viewpoint of imparting reusability of the adhesive.

Further, the first (meth) acrylate polymer (A) has a reaction in comparison with the second (meth) acrylate polymer (B) containing a monomer having a reactive functional group (b1). Sexual functional group (a1) in the single The ratio of the first (meth) acrylate polymer (A) to the monomer having the reactive functional group (b1) contained in the second (meth) acrylate polymer (B) is preferably The ratio in the second (meth) acrylate polymer (B) is small. Thereby, the first (meth) acrylate polymer (A) suppresses the reaction of the reactive functional group (a1) and the crosslinking agent (C), and the second (meth) acrylate polymer (B) contains The reactive functional group (b1) and the crosslinking agent (C) undergo a definite reaction. Thereby, a good adhesive having a maximum stress greater than that at the time of breaking or 4000% stretching can be obtained.

The first (meth) acrylate polymer (A) is preferably not contained in the molecule, and the reactivity with the crosslinking agent (C) is a reaction with the second (meth) acrylate polymer (B). When the functional group (b1) has a functional group having the same or a higher functional group, if it is contained, the content of the monomer having the functional group in the molecule is 1% by mass or less in the polymer (A). Preferably, 0.5% by mass or less is particularly preferable. When the content of the monomer is more than 1% by mass, the reaction between the second (meth) acrylate polymer (B) and the crosslinking agent (C) which is preferably 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.

Weight average molecular weight of the first (meth) acrylate polymer (A) It is 500,000 to 3 million, preferably 700,000 to 2.5 million, and particularly good for 1 million to 2 million. That is, the first (meth) acrylate polymer (A) is a high molecular weight polymer component.

The first (meth) acrylate polymer (A) has a weight average molecular weight within the above range, and a three-dimensional network structure formed by the second (meth) acrylate polymer (B), the first (methyl) The acrylate polymer (A) is well inserted into the three-dimensional network structure, and more than 2 molecules of the polymer (A) are pseudo-crosslinked structures, and the polymer (A) is a degree of freedom. The state is constrained (presumed). Further, when the polymer (A) has a relatively large molecular weight as described above, the three-dimensional network structure formed of the polymer (B) maintains a pseudo-crosslinked state and has a high molecular chain. Degree of freedom. Thus, at the time of stretching, the maximum stress is larger than the stress at the time of breaking or 4000% stretching, whereby a good adhesive is obtained. As a result, the formed 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, floating, peeling, etc. under high temperature conditions. It can be prevented.

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

The ratio of the second (meth) acrylate polymer (B) to 100 parts by mass of the first (meth) acrylate polymer (A) is 5 to 50 parts by mass, preferably 5 to 40 parts by mass. It is particularly preferably from 10 to 30 parts by mass.

The second (methyl) of the adhesive obtained from the adhesive composition containing the first (meth) acrylate polymer (A) and the second (meth) acrylate polymer (B) at the above ratio The acrylate polymer (B) (low molecular weight polymer) forms a three-dimensional network structure with the crosslinking agent (C), and the three-dimensional network structure is the first (meth) acrylate polymer (A) (high molecular weight) A structure in which two or more molecules are inserted, and the polymer (A) is a pseudo-crosslinked structure which is restrained in a state having a certain degree of freedom. Thus, a good adhesive having a maximum stress greater than that at the time of fracture or 4000% stretching was obtained. As a result, the obtained adhesive can exhibit an excellent stress relaxation rate while having an appropriate cohesive force. Thereby, the obtained adhesive has excellent durability and light leakage resistance.

The crosslinking agent (C) may, for example, be an isocyanate crosslinking agent, an epoxy crosslinking agent, an aziridine crosslinking agent, a metal chelate crosslinking agent or the like.

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 or isofluoride. An ester ring polyisocyanate such as keto diisocyanate or hydrogenated diphenylmethyl diisocyanate; and a biuret or isocyanurate of these, further ethylene glycol, propylene glycol, neopentyl glycol, Trimethylolpropane The low molecular weight active hydrogen such as castor oil contains an adduct of a compound and a reactant, and the like.

As the epoxy-based crosslinking agent, 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl group m may be exemplified. - p-xylylenediamine, ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidyl aniline, and diglycidyl Alkylamine and the like.

Examples of the aziridine-based crosslinking agent include diphenylmethyl-4,4'-bis(1-azabicyclopropanecarboxamide) and trimethylolpropane tri-β-azepine propionate. , tetramethylol methane tri-β-azepine propionate, toluene 2,4-bis(1-azacyclopropanecarboxamide), triethylene melamine, bisisoisophthalyl 1- (2-methylaziridine), tri-1-(2-methylaziridine)phosphine, trimethylolpropane tri-β-(2-methylaziridine)propionic acid, and the like.

Among the metal chelate crosslinking agents, metal atoms are chelating compounds such as aluminum, zirconium, titanium, zinc, iron, and tin, and aluminum chelate compounds are 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), the crosslinking functional group (for example, isocyanate group) of the crosslinking agent (C), and the reactive functional group (b1) of the second (meth) acrylate polymer (B) The amount of (for example, hydroxyl), usually 0.05 to 5 The equivalent weight is preferably from 0.1 to 3.5 equivalents, particularly preferably from 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 may be 30% or less, and sufficient cohesive force may not be exhibited. Further, the amount of the crosslinkable group is 0.1 equivalent or more, particularly 0.3 equivalent or more, and the durability of the obtained adhesive is further improved. On the other hand, the amount of the crosslinkable group is 3.5 equivalents or less, and the obtained adhesive is excellent in recyclability. Further, when the amount of the crosslinkable group is 1.0 equivalent or less, the crosslinking agent (C) contributes only to the formation of the three-dimensional network structure of the polymer (B), and the crosslinking of the polymer (A) can be prevented. Union. As a result, the obtained adhesive has a good stress relaxation rate.

Further, in the present embodiment, when the cross-linking agent (C) has a cross-linking property in which the reactivity between the reactive functional group (b1) and the reactive functional group (a1) is the same, various types may be used. And use it. From the viewpoint of easy control of the three-dimensional network structure formed of the second (meth) acrylate polymer (B), for example, it is said that only the isocyanate-based crosslinking agent is used, and only one type of crosslinking agent is used. Preferably, further, it is particularly preferable to use only one type of crosslinking agent.

Here, the combination of the crosslinking agent (C), the (meth) acrylate polymer (A), and (B) the reactive functional group-containing monomer is an isocyanate crosslinking agent in the crosslinking agent (C). In the case of the monomer containing the reactive functional group (a1) of the polymer (A), a monomer having a carboxyl group is preferably selected, and as the reactive functional group (b1) containing the polymer (B), a hydroxyl group is preferably selected. The monomer or the monomer having an amino group is preferably a monomer having a carboxyl group as the monomer having a reactive functional group (b2) of the polymer (B).

On the other hand, the crosslinking agent (C) is an epoxy crosslinking agent, aziridine When a crosslinking agent or a metal chelate crosslinking agent is used, as a monomer containing the reactive functional group (a1) of the polymer (A), a monomer having a hydroxyl group is preferred, and a reaction of the polymer (B) is contained. The monomer having a functional group (b1) is preferably a monomer having a carboxyl group, and as the monomer having a reactive functional group (b2) of the polymer (B), a monomer having a hydroxyl group is preferably selected.

The flexibility of the bond formed between the crosslinking agent (C) and the polymer (B), the stability of the crosslinking reaction, and further, the reactive group of the polymer (A) and the decane coupling agent (D) The reaction is suitable, and the durability of the obtained adhesive is high. The crosslinking agent (C) uses an isocyanate crosslinking agent, and the monomer containing the reactive functional group (a1) of the polymer (A) contains a carboxyl group. The monomer, the monomer containing the reactive functional group (b1) of the polymer (B) is a monomer having a hydroxyl group, and the monomer containing the reactive functional group (b2) is not particularly preferred.

The adhesive composition of the present embodiment more preferably contains a decane coupling agent (D). When such a decane coupling agent (D) is contained, when the first (meth) acrylate polymer (A) has a carboxyl group, the organic reactive group of the decane coupling agent (D), etc., and the first (methyl group) a carboxyl group reaction of the acrylate polymer (A), and on the other hand, an alkoxymethylalkyl group of the decane coupling agent (D) acts on the surface of the adherend such as a glass substrate, and thus, for example, a polarizing plate When it 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 alkoxycarbenyl group in the molecule has good compatibility with an adhesive component, and a light-transmitting material such as substantially transparent is preferable. . Such decane The amount of the coupling agent (D) to be added is preferably from 0.01 to 0.5 parts by mass, preferably from 0.05 to 0.3 parts by mass, per 100 parts by mass of the first (meth) acrylate polymer (A).

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

In the above adhesive composition, various additives commonly used in acrylic adhesives, such as an adhesion-imparting agent, an oxidation inhibitor, an ultraviolet absorber, a light stabilizer, a softener, a filler, a charge inhibitor, and a refractive index, are used as needed. Adjusters and the like can be added.

When the above-mentioned adhesive composition is mixed with the first (meth) acrylate polymer (A) and the second (meth) acrylate polymer (B), a crosslinking agent (C) may be added at any stage. And adding a decane coupling agent (D) as needed, and manufacturing.

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

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. The azo compound may, for example, be 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile) or 1,1'-azobis(cyclohexane). 1-nitrile), 2,2'-azobis(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-hydroxymethylpropane) Nitrile), 2,2'-azobis[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, peroxybutyrate t-butyl ester (t- Butylperoxypyvalate), (3,5,5-trimethylcyclopentanone) peroxide, dipropionyl peroxide, and diacetyl peroxide.

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

The adhesive composition is diluted to a dilution solvent of the coating solution, and examples thereof include aliphatic hydrocarbons such as hexane, heptane, and cyclohexane; and aromatics such as toluene and xylene. Aromatic hydrocarbon; halogenated hydrocarbon such as dichloromethane or dichloroethane; alcohol such as methanol, ethanol, propanol, butanol or 1-methoxy-2-propanol; acetone, methyl ethyl ketone, 2 a ketone such as pentanol, isoflurane or cyclopentanone; an ester of ethyl acetate or butyl acetate; a cellosolve solvent such as ethyl cellosolve;

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

The above-mentioned adhesive is formed by crosslinking the above-mentioned adhesive composition. The crosslinking of the above adhesive composition is carried out by heat treatment. Further, in such heat treatment, volatilization of the diluted solvent or the like of the adhesive composition can also serve as a drying treatment.

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

In the above heat treatment (and aging), the second (meth) acrylate polymer (B) can be crosslinked by the crosslinking agent (C), whereby a dense three-dimensional network structure can be formed. Further, in the three-dimensional network structure, two or more molecules of the first (meth) acrylate polymer (A) are not direct chemical bonds, or Obtained with the insertion of very few chemical bonds, the polymer (A) is constrained, and a pseudo-crosslinked structure is formed. Thus, when the tensile force is obtained, the maximum stress is an adhesive which is larger than the stress at the time of breaking or 4000% stretching. Further, when the first (meth) acrylate polymer (A) has a carboxyl group, the first (meth) acrylate polymer (A) is reacted with the decane coupling agent (D), and the obtained adhesive is oriented. The adhesion durability of the glass substrate such as a liquid crystal cell is high.

The gel ratio of the adhesive of the present embodiment is preferably from 30 to 90%, particularly preferably from 40 to 80%, more preferably from 45 to 75%. If the gel ratio is such that the degree of crosslinking is within this range, the three-dimensional network structure obtained by crosslinking the second (meth) acrylate polymer (B) can be formed well, and the maximum stress at the time of stretching Adhesive with large stress at break or 4000% stretch. Thus, the adhesive is excellent in both light leakage resistance and durability. 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 to the release sheet, and after heating, the gel ratio after storage for 7 days in an environment of 23° C. and 50% RH was carried out. The gel ratio of the adhesive, the value of which varies before the aging period passes. From such a viewpoint, if the aging period has elapsed or not, if it is stored in an environment of 23° C. and 50% RH for 7 days, the gel ratio may be within the above range.

The adhesive described above is preferably 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 adhesive has excellent stress relaxation rate and is attached to the body. When the dimensional change is large, the stress obtained by the dimensional change is absorbed by the adhesive layer. Since it is relaxed, it can be peeled off from the adherend for a long period of time, and as described above, light leakage can be effectively prevented when used in an optical component. That is, when the adhesive of the present embodiment is used in an optical member, light leakage resistance and durability can be simultaneously achieved.

[adhesive sheet]

As shown in Fig. 1, the adhesive sheet 1A of the first embodiment is formed by laminating the base material 13 on the adhesive layer 11 and the adhesive layer 11 which are laminated on the release surface of the release sheet 12 and the release sheet 12 from the bottom to the top. Composition.

In the adhesive sheet 1B of the second embodiment, the two release sheets 12a and 12b are held by the two release sheets 12a and 12b in contact with the peeling surfaces of the two release sheets 12a and 12b. The adhesive layer 11 is formed. In addition, the peeling surface of the peeling sheet in this specification is a surface which has the peeling property in the peeling sheet, the peeling process was performed, and the peeling process was not performed, and the peeling surface was also carried out.

Regardless of the one of the adhesive sheets 1A, 1B, the adhesive layer 11 is an adhesive obtained by crosslinking the above-mentioned adhesive composition.

The thickness of the adhesive layer 11 can be 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 as an adhesive layer for a polarizing plate. The occasion is 10 to 50 μm, and particularly preferably 10 to 30 μm.

The substrate 13 is not particularly limited, and generally used as a substrate sheet of an adhesive sheet can be used. For example, a woven fabric or a nonwoven fabric made of fibers of rayon, acrylic, polyester, or the like, other than the optical member; Paper for upper quality paper, cellophane, impregnated paper, coated paper, etc.; metal foil such as aluminum or copper; foam of urethane foam, polyethylene foam, etc.; polyethylene terephthalate , polyester film of polybutylene terephthalate, polybutylene naphthalate, cellulose film such as triacetyl cellulose film, polyurethane film, polyethylene film, polypropylene film, polyvinyl chloride film, Polyvinylidene chloride film, polyvinyl alcohol film, ethylene vinyl acetate copolymer film, polystyrene film, polycarbonate film, acrylic film, polybornene resin film, cycloolefin resin film, etc. A plastic film; a laminate of two or more of these. Plastic film, one-axis rolling or two-axis rolling can also be used.

The optical member may, for example, be a polarizing plate (polarized light film), a polarizer, a retardation film (retardation film), a viewing angle compensation film, a brightness enhancement film, a contrast improving film, a liquid crystal polymer film or the like. Among them, the polarizing plate (polarizing film) is easy to shrink 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, it is usually 10 μm to 500 μm, preferably 50 μm to 300 μm.

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

In the peeling surface of the release sheet (particularly the surface in contact with the adhesive layer 11), a release treatment is preferred. The release agent used for the release treatment may, for example, be a release agent of an alkyd, a siloxane, a fluorine, an unsaturated polyester, a polyolefin, or a wax.

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

The adhesive sheet 1A is produced by applying the above-mentioned adhesive composition solution (coating solution) to the release surface of the release sheet 12, and heat-treating to form the adhesive layer 11, and then performing the base on the adhesive layer 11. Lamination of the material 13. Thereafter, it is preferred to set the ripening period.

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

Further, in the above-mentioned pressure-sensitive adhesive sheet 1B, a coating solution containing the above-mentioned adhesive composition is applied onto a release surface of one release sheet 12a (or 12b), and after heat treatment, the adhesive layer 11 is applied thereto. The other surface of the adhesive layer 11 overlaps the peeling faces of the release sheets 12b (or 12a).

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

Here, for example, in the manufacture of a liquid crystal display device comprising a liquid crystal cell and a polarizing plate, the substrate 13 of the adhesive sheet 1A uses a polarizing plate, and the adhesive sheet 1A The release sheet 12 is peeled off, and the exposed adhesive layer 11 and the liquid crystal cell are bonded together.

Further, for example, in the production of a liquid crystal display device in which a retardation plate is provided between a liquid crystal cell and a polarizing plate, as an example, first, the release sheet 12a (or 12b) on one surface of the adhesive sheet 1B is peeled off, and the adhesive sheet 1B is exposed to an adhesive. The layer 11 and the phase difference plate are bonded. Next, the release sheet 12 of the adhesive sheet 1A used as the polarizing plate of the base material 13 is peeled off, and the exposed adhesive layer 11 of the adhesive sheet 1A is bonded to the retardation plate. Further, the release sheet 12b (or 12a) on the other surface is peeled off from the adhesive layer 11 of the adhesive sheet 1B, and the exposed adhesive layer 11 of the adhesive sheet 1B is bonded to the liquid crystal cell.

The above adhesive sheets 1A, 1B and the adhesive layer 11 have excellent stress relaxation ratio. Therefore, for example, when adhesion of a polarizing plate is applied, stress due to deformation of the polarizing plate can be absorbed by the adhesive layer 11 . Relaxation, thereby achieving excellent light leakage resistance and high durability.

The embodiments described above are intended to understand the present invention. The invention is not limited. Therefore, the above embodiments disclose various elements, and all design changes and equivalents of the scope of the technology of the invention are included.

For example, the release sheet 12 of the adhesive sheet 1A can be omitted, and any of the release sheets 12a, 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 like, and the scope of the present invention is not limited to the examples.

[Example 1]

1. Modulation of polymer (A)

97.0 parts by mass of n-butyl acrylate, 3.0 parts by mass of acrylic acid, 200 parts by mass of ethyl acetate, and 2,2' were added to a reaction vessel having a stirrer, a thermometer, a reflux cooler, a dropping device, and a nitrogen introduction tube. - 0.08 parts by mass of azobisisobutyronitrile, and the air in the above reaction vessel was replaced with nitrogen. Under the nitrogen atmosphere, the reaction solution was heated to 60 ° C while stirring, 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 it was confirmed that a polymer (A) having a weight average molecular weight of 1.5 million was formed.

2. Modulation of polymer (B)

To a reaction vessel having a stirrer, a thermometer, a reflow 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 200 parts by mass of ethyl acetate were added. 0.16 parts by mass of 2,2'-azobisisobutyronitrile and 0.3 parts by mass of 2-mercaptoethanol, and the air in the above reaction vessel was replaced with nitrogen. Under a nitrogen atmosphere, the reaction solution was heated to 70 ° C while stirring, and after 6 hours of reaction, it was cooled to room temperature. Here, one part of the obtained solution was measured by the following method GPC, 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. The crosslinking agent (C), the hydroxyl group of the polymer (B) is 0.6 equivalents of the equivalent amount of trimethylolpropane 2.21 parts by mass of a benzyl diisocyanate (TDI-based) adduct (trade name: CORONATE-L, manufactured by Nippon Polyurethane Co., Ltd.) was added. Finally, 0.2 parts by mass of 3-glycidoxypropyltrimethoxydecane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KBM403) was added as a decane coupling agent (D), and the mixture was sufficiently stirred to obtain an adhesive composition. Dilute the solution.

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 acid HEA: 2-hydroxyethyl acrylate 4HBA: 4-hydroxybutyl acrylate

[plasticizer]

. ADEKASIZER-C-8:

Trimellitic acid ester plasticizer (tris(2-ethylhexyl) trimellitate) (made by Asahi Kasei 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 (Mitsui Chemical Polyurethane Co., Ltd., 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-isocyanatepropyltriethoxydecane (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 decane-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 so that the thickness of the coating layer after drying was 25 μm, and then heat treatment was performed at 90 ° C for 1 minute to form an adhesive layer.

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

[Examples 2 to 12, Comparative Examples 1 to 5]

The kind and ratio of each monomer constituting the adhesive composition, the kind and amount of the plasticizer, the crosslinking agent, and the decane coupling agent, and the composition of the polymer (A) and the polymer (B) are as shown in Table 1. A polarizing plate with an adhesive layer was produced in the same manner as in Example 1 except that the change was shown.

Here, the weight average molecular weight (Mw) described above is a polystyrene exchange measured by gel permeation chromatography (GPC) under the following conditions (GPC measurement). Calculated weight average molecular weight.

<Measurement conditions>

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

. GPC column (the following sequence is passed): made by Tosoh

TSK guard column HXL-H TSK gel GMHXL (×2) TSK gel G2000HXL

. Determination of solvent: tetrahydrofuran

. Measuring temperature: 40 ° C

[Experimental Example 1] (Measurement of gel ratio)

The polarizing plate used in the production of the polarizing plate with the adhesive layer in the example or the comparative example was changed, and one side of the polyethylene terephthalate film was peeled off with a decane-based release agent. The treated release sheet (SP-PET3801, thickness: 38 μm) was used to produce an adhesive sheet. Specifically, the release sheet was laminated on the exposed adhesive layer of the formed body of the release sheet/adhesive layer (thickness: 25 μm) obtained in the production process of the example or the comparative example, and the release-treated side was phase-disposed. Pick up. Thus, an adhesive sheet composed of a release sheet/adhesive layer/release sheet was produced.

The obtained adhesive sheet was aged at 23 ° C, 50% RH for 7 days. Thereafter, the adhesive sheet was formed into a sample having a size of 80 mm × 80 mm, and the adhesive layer was wrapped with a polyester mesh (mesh 200), and the quality of the adhesive was weighed with a precision balance. Take the quality at this time as M1.

Next, the adhesive for the polyester net bag was immersed in ethyl acetate at room temperature (23 ° C) for 24 hours. After that the adhesive is removed at a temperature of 23 °C, air humidity of 50% in an environment of 24 hours, and further drying in an oven at 80 ° C for 12 hours. Only the quality of the dried adhesive is weighed with a precision balance. Take the quality at this time 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 similar to the adhesive sheet used for the measurement of the gel ratio was prepared (completed in 7 days). Regarding the adhesive layer of the adhesive sheet, Haze (NDH2000, manufactured by Nippon Denshoku Industries Co., Ltd.) and Haze value (%) according to JIS K7105 (also referred to as Hz (%) )) Perform the measurement. 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 layer was adhered to an aluminum-free glass (Eagle XG, manufactured by Corning Co., Ltd.), and then an autoclave made by Kurihara Co., Ltd. was pressurized at 0.5 MPa at 50 ° C for 20 minutes.

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

◎: No problem in the four sides ○: Among the four sides, there is no problem from the outer peripheral end to the portion of 0.6 mm or more ×: at least one of the four sides has a floating from the outer peripheral end to the 0.6 mm or more. Adhesion of 0.1 mm or more, peeling, foaming, streaking, etc. Abnormal appearance of the agent

[Experimental Example 4] (Light leakage resistance test)

The polarizing plate with the adhesive layer obtained in the example or the comparative example was 233 mm × 309 mm by a cutting device (super knife manufactured by Takino Seisakusho Co., Ltd., adjusted to PN1-600). The peeling sheet was peeled off, and the exposed adhesive layer was adhered to the flawless glass (manufactured by Corning Co., Ltd., Eagle XG), and the autoclave made by Kurihara Co., Ltd. was pressurized at 0.5 MPa and 50 ° C for 20 minutes. Further, in the above-described bonding, the polarizing plate with the adhesive layer was placed in a Nicols cross state (polarizing axis: ∠45°, ∠135°) in the polarizing plate. In this state, the film was allowed to stand 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 following method. The results are shown in Table 2.

<Light leakage evaluation: △L*>

Using 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 difference in brightness was ΔL*, using the formula ΔL*=[(b+c+d+e ) /4]-a (However, a, b, c, d, and e, respectively, in the A field, the B field, the C field, the D field, and the E field, a predetermined measurement point (one place in the central part of each field) The lightness in .) is obtained as light leakage. The smaller the value of ΔL*, the less light leakage is. Further, L*max represents the maximum brightness in the above-described entire field.

<Light leakage evaluation: visual inspection>

The sample was placed on a flat panel illumination lamp (HF-SL-A312LC, illuminance: 26,000 Lux, brightness: 10,000 cd). The image was recorded by a binary-dimensional color luminance meter (manufactured by Konica Minolta Co., Ltd., CA-2000), and converted into a luminance distribution image by using analysis software (CA-S20w, manufactured by Konica Minolta Co., Ltd.). The luminance distribution image of the obtained sample was evaluated using the evaluation criteria of Fig. 4 .

[Experimental Example 5] (tensile experiment)

On the peeling treatment surface of a release sheet (SP-PET3811, manufactured by Linde Co., Ltd.) which was subjected to a release treatment on a single side of a polyethylene terephthalate film with a decane-based release agent, and comparison The adhesive composition prepared in the example was applied to a thickness of 25 μm after drying, and heated at 100 ° C for 1 minute to form an adhesive layer. The release layer of the other release sheet (SP-PET3801, manufactured by Linde Co., Ltd.) which was subjected to the release treatment of the adhesive layer and the polyethylene terephthalate film on one side with a decane-based release agent was attached. Get the adhesive sheet.

The adhesive layer was laminated in a plurality of layers so that the total thickness of the adhesive layer in the adhesive sheet was 500 μm, and only the outermost release sheet of the laminate was left, and it was placed under an atmosphere of 23 ° C and a humidity of 50%. One night. Thereafter, a sample having a thickness of 10 mm and a length of 75 mm was cut out from the adhesive sheet in which the pressure-sensitive adhesive layer was laminated, and the peeling sheet in which the outermost layer of the laminate was laminated was peeled off, and the sample was placed thereon to have a measurement range of 10 mm wide by 20 mm long. The stress (N) was measured by using a tensile tester (tensilon, manufactured by Aotech Co., Ltd.) at a tensile strength of 200 mm/min and 4000% under an environment of 23 ° C and 50% RH. The stress at 4000% stretching or at break, and the maximum stress are shown in Table 2.

As is clear from Table 2, in the tape obtained in the example, the maximum stress was greater than the stress at the time of stretching of 4000% or at the time of breaking, and the durability and the light leakage resistance were excellent. On the other hand, in the polarizing plate with an adhesive layer obtained in the comparative example, the maximum stress and the stress at the time of 4,000% stretching or breaking were the same, and both of the durability and the light leakage resistance were inferior.

The adhesive of the present invention is suitable for adhesion of optical members such as polarizers and phase difference plates. Further, the pressure-sensitive adhesive sheet of the present invention is suitable 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 measurement of the light leakage resistance test in the polarizing plate with the adhesive layer attached.

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 (6)

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) acrylate polymer having a weight average molecular weight of 8,000 to 300,000 (B) a component which is crosslinked, and the second (meth) acrylate polymer (B) before crosslinking is contained as a constituent component, and contains a reactive functional group of 5% by mass or more and 50% by mass or less. The monomer, when stretched, has a maximum stress greater than the stress at break or 4000% stretch. An adhesive according to claim 1 which contains 50% by mass or more of a (meth) acrylate polymer having a weight average molecular weight of 500,000 to 3,000,000 and a gel ratio of 30 to 90%. 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. An adhesive sheet having a substrate and an adhesive layer formed of the adhesive of any one of claims 1 to 3. The adhesive sheet of claim 4, wherein the substrate is an optical component. An adhesive sheet comprising: two release sheets; and an adhesive layer that is in contact with the release surface of the two release sheets and held by the release sheet, wherein the adhesive layer is applied The adhesive of any one of the patent ranges 1 to 3 is formed.