TWI493002B - An adhesive composition, an adhesive, and an adhesive sheet - Google Patents

Description

Adhesive composition, adhesive, and adhesive sheet

The present invention relates to an adhesive composition, a method for producing an adhesive composition, an adhesive (a material for crosslinking an adhesive composition), and an adhesive sheet; and more particularly to an optical suitable as a polarizing plate or the like An adhesive composition for a member, a method for producing an adhesive composition, an adhesive, and an adhesive sheet.

Generally, in a liquid crystal panel, a polarizing plate or a phase difference plate is bonded to a glass substrate or the like. Therefore, an adhesive layer formed of an adhesive composition is often used. However, the optical member such as a polarizing plate or a retardation plate is likely to shrink due to heat or the like, and therefore shrinks due to the heat history. As a result, it is pointed out that the adhesive layer laminated on the optical member cannot follow the shrinkage. The interface is peeled off (so-called floating, peeling), or a problem of light leakage (so-called fading) caused by the deviation of the optical axis of the optical member due to the stress caused by shrinkage of the optical member occurs.

As a method for preventing this, (1) a method of suppressing shrinkage of an optical member by bonding an adhesive layer having a high adhesive force and good form stability to an optical member such as a polarizing plate or the like (2) A method of using an adhesive layer having a small stress when the optical member is shrunk. As a method of (1), as shown in Patent Document 1, an adhesive layer having a high storage modulus is used effectively. On the other hand, as the method of (2), an adhesive layer which is soft in response to deformation and which is excellent in stress relaxation property is used. However, in the state in which such an adhesive layer having good stress relaxation property is attempted, it is necessary to extremely lower the crosslinking density in the adhesive layer. In such a case, there is a problem that the strength of the pressure-sensitive adhesive layer itself is lowered to deteriorate the durability.

Then, in Patent Documents 2 to 4, a plasticizer, a fluid paraffin, an urethane elastomer, or the like is added to the propylene-based adhesive to replace the crosslinking density of the adhesive layer extremely. While the obtained adhesive composition is moderately softened, stress relaxation property is imparted to the adhesive layer, and it is attempted to obtain light leakage resistance and durability.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2006-235568

[Patent Document 2] Japanese Patent Laid-Open No. Hei 5-45517

[Patent Document 3] Japanese Patent Laid-Open No. Hei 9-137143

[Patent Document 4] Japanese Patent Laid-Open Publication No. 2005-194366

However, the adhesive layer formed by adding the adhesive composition of a plasticizer or a fluid paraffin causes various problems such as contamination of the liquid crystal cell due to the outflow of the plasticizer or the fluid paraffin over time. Further, in the case where the adhesive composition of the ethyl urethane elastomer is added, the amount of the urethane elastomer is limited in terms of compatibility with other components, and therefore, the stress relaxation property is The improvement is insufficient, and the problem of white turbidity or the like occurs due to the compatibility of the propylene-based adhesive and the urethane elastomer. As described above, in the prior art, it is not easy to fundamentally improve the light leakage resistance and durability of the adhesive layer formed of the adhesive composition for an optical member.

The present invention has been made in view of such a solid shape, and an object thereof is to provide an adhesive composition which is excellent in light leakage resistance and durability when applied to an optical member such as a polarizing plate, and the adhesive composition Manufacturing method, adhesive, and adhesive sheet.

In order to achieve the above object, in the first aspect, the present invention provides an adhesive composition comprising a first (meth) acrylate copolymer (A) having a weight average molecular weight of 700,000 to 2.5 million, and a weight average. The (meth) acrylate copolymer (B) having a molecular weight of 8,000 to 250,000 and the crosslinking agent (C) and the second (meth) acrylate copolymer (B) having a molecular weight of 100 parts by mass or so The adhesive composition of the first (meth) acrylate copolymer (A) in an amount of 5 to 50 parts by mass, wherein the second (meth) acrylate copolymer (B) contains The monomer having the functional group (b1) having high reactivity with the crosslinking agent (C) is a structural component, and in the second (meth) acrylate copolymer (B), it is the aforementioned single The copolymer of the first (meth) acrylate copolymer (A) does not contain a monomer having a functional group reactive with the crosslinking agent (C), and the copolymer is a structure. a component or a functional group (a1) having the aforementioned functional group (b1) having a reactivity lower than that of the aforementioned (meth) acrylate copolymer (B) The monomer is used as a structural component (Invention 1).

The adhesive which crosslinks the adhesive composition of the above invention (Invention 1) is conventionally formed by the low molecular weight copolymer (B) which is used as a plasticizer to form three times due to crosslinking. The structure of the meta-mesh, in its cubic mesh structure, entangles the high-molecular-weight copolymer (A) without cross-linking, and exerts good stress relaxation. By using an adhesive having such a good stress relaxation property, an adhesive sheet which is excellent in both light leakage resistance and durability when applied to an optical member such as a polarizing plate can be obtained.

In the above invention (Invention 1), the first (meth) acrylate copolymer (A) is preferably a monomer which does not contain a functional group having high reactivity with the crosslinking agent (C). Structural component (Invention 2).

In the above invention (Inventions 1 and 2), it is preferable that the functional group (a1) which is low reactivity of the first (meth) acrylate copolymer (A) and the crosslinking agent (C) is a carboxyl group, The functional group (b1) having a high reactivity with the crosslinking agent (C) of the second (meth) acrylate copolymer (B) is a hydroxyl group, and the crosslinking agent (C) is an isocyanate crosslinking agent. (Invention 3).

In the above invention (Invention 3), the first (meth) acrylate copolymer (A) preferably contains 0 to 15% by mass of the carboxyl group-containing monomer as a monomer unit constituting the copolymer (Invention 4). Thereby, the adhesive sheet is obtained, which has good reworkability.

In the above invention (Inventions 3 and 4), the second (meth) acrylate copolymer (B) preferably contains 3 to 40% by mass of the hydroxyl group-containing monomer as a monomer unit constituting the copolymer. (Invention 5). Thereby, the adhesive sheet is obtained, and the durability is further improved.

In the above invention (Inventions 3 to 5), the content of the isocyanate crosslinking agent is preferably the isocyanate group of the isocyanate crosslinking agent relative to the second (meth) acrylate copolymer (B). The amount of the functional group (b1) having high reactivity with the crosslinking agent (C) is 0.1 to 5 equivalents (Invention 6).

In the above invention (Inventions 1 to 6), it is preferable to further contain a decane coupling agent (D) (Invention 7).

In the above invention (Invention 7), the content of the decane coupling agent (D) is preferably 0.05 to 0.5 parts by mass based on 100 parts by mass of the first (meth) acrylate copolymer (A). (Invention 8).

In a second aspect, the present invention provides a method for producing an adhesive composition, which is a method for producing the above-mentioned adhesive composition (Inventions 1 to 6), which comprises: a conversion ratio of 50 to 90%, for constitution The monomer (1) of the first (meth) acrylate copolymer (A) is subjected to radical polymerization to produce the first (meth) acrylate copolymer (A) (1); In the presence of the (meth) acrylate copolymer (A), the monomer remaining in the polymerization of the first (meth) acrylate copolymer (A) and the crosslinking agent (C) a monomer of the highly reactive functional group (b1), which is subjected to radical copolymerization to produce the second (meth) acrylate copolymer (B) (2); and the aforementioned crosslinking agent (C) Process (3) (Invention 9).

In the above invention (Invention 9), it is preferred to carry out the process (2) of the above-mentioned second (meth) acrylate copolymer (B) at a conversion ratio of 70 to 100%, and to remain in the aforementioned first ( The monomer in the polymerization of the methyl acrylate copolymer (A) and the monomer having the functional group (b1) having high reactivity with the crosslinking agent (C) are subjected to radical copolymerization (Invention 10).

In the above invention (Inventions 9, 10), it is preferable to further include a process of adding the decane coupling agent (D) (Invention 11) in the state in which the above-mentioned adhesive composition (Inventions 7, 8) is produced.

In the third aspect, the present invention provides an adhesive which is crosslinked by the above-mentioned adhesive composition (Inventions 1 to 8) (Invention 12).

In a fourth aspect, the present invention provides an adhesive sheet comprising an adhesive sheet of a substrate and an adhesive layer, wherein the adhesive layer is composed of the aforementioned adhesive (Invention 12) (Invention 13).

In the above invention (Invention 13), the substrate is preferably an optical member (Invention 14).

According to a fifth aspect of the present invention, there is provided an adhesive sheet comprising two release sheets and an adhesive sheet sandwiched between the release sheets and bonded to the release layer of the release sheets of the two release sheets. The adhesive layer is composed of the above-mentioned adhesive (Invention 12) (Invention 15).

The adhesive for crosslinking the adhesive composition of the present invention is conventionally formed by a low molecular weight copolymer which is used as a plasticizer to form a three-dimensional network structure due to crosslinking, three times The structure of the meta-mesh, winding a high-molecular-weight copolymer without cross-linking, and exerting good stress relaxation. By using an adhesive having such a good stress relaxation property, an adhesive sheet which is excellent in both light leakage resistance and durability when applied to an optical member such as a polarizing plate can be obtained.

Hereinafter, embodiments of the present invention will be described.

(adhesive composition)

The adhesive composition of the present embodiment contains a first (meth) acrylate copolymer (A) having a weight average molecular weight of 700,000 to 2.5 million, and a second (meth) having a weight average molecular weight of 8,000 to 250,000. The acrylate copolymer (B) and the crosslinking agent (C) preferably further contain a decane coupling agent (D). Further, in the present specification, the term "(meth)acrylate" means both acrylate and methacrylate. Other similar terms are the same.

The (meth) acrylate copolymer (B) of the second aspect is a monomer having a functional group (b1) having high reactivity with the crosslinking agent (C) as a constituent component, a copolymer of the monomer ( The composition ratio of B) is more than 1% by mass.

On the other hand, the first (meth) acrylate copolymer (A) is a structural component which does not contain a functional group having reactivity with the crosslinking agent (C), or has a crosslinking agent. The monomer (C) having a lower reactivity than the functional group (a1) of the functional group (b1) of the (meth) acrylate copolymer (B) is used as a structural component.

The (meth) acrylate copolymer (A) or (B) is preferably a (meth) acrylate having a carbon number of 1 to 20 and a monomer having a reactive functional group in an alkyl group of the ester moiety (including Reactive functional monomer) and copolymers of other monomers used as required. Further, it is preferable that the first (meth) acrylate copolymer (A) is a structural component without containing the reactive functional group-containing monomer.

The (meth) acrylate series having 1 to 20 carbon atoms of the alkyl group as the ester moiety is, for example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, or (methyl). Butyl acrylate, amyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, Ethyl (meth)acrylate, dodecyl (meth)acrylate, tetradecyl (meth)acrylate, hexadecyl (meth)acrylate, stearin (meth)acrylate, and the like. These systems may be used alone or in combination of two or more.

On the other hand, as the reactive functional group-containing single system, a monomer having a hydroxyl group in the molecule (hydroxy group-containing monomer), a monomer having a carboxyl group in the molecule (carboxy group-containing monomer), and a molecule are preferably used. A monomer having an amine group (an amine group-containing monomer) or the like.

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

Examples of the carboxyl group-containing monomer include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, citraconic acid, and vinyl acetate. These systems may be used alone or in combination of two or more.

Examples of the amine group-containing monomer include, for example, aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, and N,N-dimethylamino (meth)acrylate. Propyl, t-butylaminoethyl (meth)acrylate, and the like. These systems may be used alone or in combination of two or more.

Further, as the other monomer series, for example, an aliphatic ring (meth) acrylate such as cyclohexyl (meth) acrylate or a phenyl (meth) acrylate may have an aromatic ring (methyl group). a non-crosslinkable acrylamide, styrene or the like such as acrylate, acrylamide or methacrylamide. These systems may be used alone or in combination of two or more.

Further, the reactivity of the reactive functional group (a1) monomer used in the first (meth) acrylate copolymer (A) and the (meth) acrylate copolymer (B) used in the second (meth) acrylate copolymer (B) The choice of the functional group (b1) monomer is determined by the reactivity with the crosslinking agent (C) used. The details are described later.

Here, the second (meth) acrylate copolymer (B) contains the reactive functional group (b1)-containing monomer in an amount of more than 1% by mass, and the upper limit thereof is usually 50% by mass. It is preferable to contain 3 to 40% by mass of the above-mentioned reactive functional group-containing (b1) monomer, and particularly preferably 5 to 25% by mass. By the above range, the degree of crosslinking of the reactive functional group (b1)-containing monomer, and preferably the second (meth)acrylate copolymer (B), and the first The combination of the acrylate copolymer (A) and the stress relaxation property of the obtained adhesive agent are good. In addition, when the content of the reactive functional group-containing (b1) monomer is 1% by mass or less, the crosslinking of the second (meth) acrylate copolymer (B) is insufficient, and thus the durability is lowered. On the other hand, when the content of the reactive functional group-containing (b1) monomer exceeds 50% by mass, the crosslinking of the second (meth) acrylate copolymer (B) becomes excessive, which may be lowered by this. Appropriate for the attachment of the attached body. In addition, the upper limit of the content of the monomer containing the reactive functional group (b1) is 40% by mass, and the durability of the adhesive sheet is further improved.

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

The weight average molecular weight of the second (meth) acrylate copolymer (B) is 8,000 to 250,000, preferably 20,000 to 150,000. That is, the second (meth) acrylate copolymer (B) is a low molecular weight polymer component. Further, the weight average molecular weight of the present specification is a value in terms of polystyrene measured by gel permeation chromatography (GPC).

The weight average molecular weight of the (meth) acrylate copolymer (B) of the second embodiment is within the above range, and the adhesive composition of the present embodiment forms a unique three-dimensional mesh structure, which contributes to good Stress relaxation. That is, the weight average molecular weight of the (meth)acrylate copolymer (B) of the second is less than 8,000, and a good three-dimensional mesh structure cannot be obtained. On the other hand, when the weight average molecular weight of the (meth) acrylate copolymer (B) exceeds 250,000, the compatibility is lowered, and the copolymer (A) and the copolymer (B) are not easily entangled. In the state, it is not easy to form a unique mesh structure as a purpose, and it is deteriorated in durability and reworkability.

The (meth) acrylate copolymer (A) of the first aspect is a structural component which does not contain a functional group having reactivity with the crosslinking agent (C), or contains a crosslinking agent (C). The monomer having a lower reactivity than the functional group (a1) of the aforementioned functional group (b1) of the (meth) acrylate copolymer (B) is used as a structural component, and then preferably, does not contain and The monomer having a highly reactive functional group of the crosslinking agent (C) serves as a structural component.

The (meth) acrylate copolymer (A) of the first embodiment may not contain a monomer having a functional group reactive with the crosslinking agent (C), but contains a reactivity lower than that of the second (A) When the monomer of the reactive functional group (a1) of the reactive functional group (b1) of the acrylate copolymer (B) is promoted, the second (meth) acrylate copolymer (B) and the crosslinking agent are promoted ( In the reaction of C), or in the state in which the decane coupling agent (D) is used, the reactive functional group (a1) of the (meth) acrylate copolymer (A) of the first is reacted with the decane coupling agent (D). The alkoxymethyl sulfonyl group or the like can adjust the degree of aggregation of the first (meth) acrylate copolymer (A), and can obtain desired bonding properties, and an ideal state occurs.

In the state in which the (meth) acrylate copolymer (A) contains the reactive functional group (a1)-containing monomer, the content thereof is usually 20% by mass or less, preferably 15% by mass or less. It is particularly preferably 10% by mass or less. When the content of the reactive functional group-containing (a1) monomer exceeds 20% by mass, the first (meth) acrylate copolymer (A) is excessively aggregated, and the required stress relaxation property may not be obtained. Further, the content of the reactive functional group (a1)-containing monomer is preferably 15% by mass or less from the viewpoint of imparting reworkability.

The (meth) acrylate copolymer (A) of the first embodiment preferably does not contain a (meth) acrylate copolymer (B) having the same reactivity as the crosslinking agent (C) in the molecule. a monomer having a functional group of the reactive functional group (b1), but it is assumed that, in the state of being contained, the content of the monomer having the functional group in the molecule is preferably in the copolymer (A) It is 1% by mass or less, and particularly preferably 0.5% by mass or less. When the content of the monomer exceeds 1% by mass, the reaction of the second (meth) acrylate copolymer (B) and the crosslinking agent (C) which should be preferentially reacted may be hindered.

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

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

The weight average molecular weight of the (meth) acrylate copolymer (A) of the first is in the above range, and the ternary mesh structure formed by the (meth) acrylate copolymer (B) of the second is good. The first (meth) acrylate copolymer (A) is wound around, contributing to good stress relaxation, and adhesion to the adherend or joint durability under high heat and humidity. It is sufficient to prevent floating, peeling, and the like.

Here, when the weight average molecular weight of the first (meth) acrylate copolymer (A) is less than 700,000, the cohesive force of the component (A) is lowered, which may deteriorate the durability and reworkability. Further, when the weight average molecular weight of the first (meth) acrylate copolymer (A) exceeds 2.5 million, the obtained adhesive is excessively hard, and the required stress relaxation property may not be obtained.

The ratio of the (meth) acrylate copolymer (B) of the second aspect to 100 parts by mass of the first (meth) acrylate copolymer (A) is 5 to 50 parts by mass, preferably 10 to 30 parts by mass. Share.

Adhesive obtained by containing the adhesive composition of the first (meth) acrylate copolymer (A) and the second (meth) acrylate copolymer (B) in the above ratio, the second The (meth) acrylate copolymer (B) (low molecular weight polymer) forms a ternary mesh structure through the crosslinking agent (C), and in the ternary mesh structure thereof, by the first without crosslinking ( The structure in which the methyl acrylate copolymer (A) (high molecular weight polymer) is entangled exhibits good hardness relaxation. Further, since the strength of the obtained adhesive is maintained by the existence of the three-dimensional mesh structure, the durability is high.

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. Examples of the polyisocyanate compound include an aromatic polyisocyanate such as phenylene diisocyanate, diphenylmethane diisocyanate or benzodimethyl diisocyanate; an aliphatic polyisocyanate such as hexamethylene diisocyanate; and isophor. An alicyclic polyisocyanate such as keto diisocyanate or hydrogenated diphenylmethane diisocyanate; and these biurets, isocyanates, even ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, An adduct of a reaction product such as castor oil or the like containing a low molecular weight active hydrogen compound. These may be used alone or in combination of two or more.

As the epoxy-based crosslinking agent series, for example, 1,3-bis(N,N-diepoxypropylaminomethyl)cyclohexane, N,N,N',N'-tetraepoxypropyl group- m-Benzyldiamine, ethylene glycol diepoxypropyl ether, 1,6-hexanediol diepoxypropyl ether, trimethylolpropane diepoxypropyl ether, diepoxy Propyl aniline, diepoxypropylamine, and the like. These may be used alone or in combination of two or more.

As a series of azacyclopropane-based crosslinking agents, for example, diphenylmethane-4,4'-bis(1-azetidinylcarboxyguanamine), trimethylolpropane tris-β-azepine propane-propyl Acid ester, tetramethylol methane tri-β-azepine propionate, toluene-2,4-bis(1-azacyclopropanecarboxyguanamine), triethylene melamine, bis-p-benzoquinone- 1-(2-methylaziridine), tri-1-(2-methylaziridine)phosphine, trimethylolpropane tri-β-(2-methylaziridine)propionic acid Ester and the like. These may be used alone or in combination of two or more.

The metal chelate crosslinking agent is a chelate compound in which the metal atom is aluminum, zirconium, titanium, zinc, iron, tin or the like. However, from the viewpoint of performance, an aluminum chelate compound is preferable. As a series of aluminum chelate compounds, for example, diisopropoxy aluminum monooleylacetate acetate, monoisopropoxy aluminum bis-alkenylacetate acetate, monoisopropoxy aluminum monooleate Monoethylacetamidine acetate, aluminum dilaurate, monolaurylacetate, diisopropoxy aluminum monostearyl acetate, diisopropoxide aluminum monoisostearyl Ethyl acetate and the like. These may be used alone or in combination of two or more.

The content of the crosslinking agent (C) is preferably a reactive functional group of the crosslinkable group (for example, an isocyanate group) of the crosslinking agent (C) with respect to the (meth) acrylate copolymer (B). The amount of the group (b1) (e.g., a hydroxyl group) is 0.1 to 5 equivalents, particularly preferably 0.2 to 3 equivalents. When the amount of the crosslinkable group is less than 0.1 equivalent, the crosslinking may not be sufficiently performed. When the amount of the crosslinkable group exceeds 5 equivalents, the adhesion at the time of adhesion may be increased and the work may be deteriorated. Sex.

Further, in the present embodiment, in addition to the above-mentioned crosslinking agent (C), a copolymer having a reactivity higher than that of the copolymer (B) reactive functional group (b1) may be used in combination within a range not impairing the effects of the present invention. A) Other cross-linking agent which is reactive with the reactive functional group (a1) (indicates the type of residual agent other than the cross-linking agent in which the amount of the cross-linking agent is the most Crosslinker). Specifically, the reactive functional group (a1) in the copolymer (A) is a carboxyl group and the reactive functional group (b1) of the copolymer (B) is a hydroxyl group and the crosslinking agent (C) is an isocyanate crosslinking agent. In the state, a small amount of an epoxy-based crosslinking agent may be added as another crosslinking agent. The addition of such other crosslinking agent is in the three-dimensional network structure composed of the copolymer (B), and the copolymer (A) is not sufficiently wound, and is effective in a state in which the cohesive force is insufficient.

In the state in which the other crosslinking agent is added, the amount thereof is preferably 0.01 to 1 part by mass based on 100 parts by mass of the total of the copolymers (A) and (B).

Here, the combination of the reactive functional group-containing monomer as the crosslinking agent (C) and the (meth) acrylate copolymers (A) and (B) is an isocyanate-based crosslinking agent (C). In the state of the crosslinking agent, it is preferred to select a carboxyl group-containing monomer as the reactive functional group (a1) monomer of the copolymer (A), and select a hydroxyl group-containing monomer or an amine group-containing monomer as a copolymer. (B) a reactive functional group (b1)-containing monomer.

On the other hand, in the state where the crosslinking agent (C) is an epoxy crosslinking agent, an aziridine crosslinking agent or a metal chelate crosslinking agent, it is preferred to select a hydroxyl group-containing monomer as a solvent. The reactive functional group (a1)-containing monomer of the copolymer (A) is selected from the carboxyl group-containing monomer as the reactive functional group (b1)-containing monomer of the copolymer (B).

Because of the softness of the bond formed between the crosslinking agent (C) and the copolymer (B) and the stability of the crosslinking reaction, even the reactive group of the copolymer (B) is moderately reacted with the decane coupling agent (D). Further, since the cohesive force of the copolymer (B) is improved, it is particularly preferable that the crosslinking agent (C) is an isocyanate crosslinking agent, and the reactive functional group (a1) monomer of the copolymer (A) becomes The carboxyl group-containing monomer, the reactive functional group (b1)-containing monomer of the copolymer (B) becomes a hydroxyl group-containing monomer.

The adhesive composition of the present embodiment preferably further contains a decane coupling agent (D). When the decane coupling agent (D) is contained, the first (meth) acrylate copolymer (A) has a carboxyl group, the alkane methoxyalkyl group of the decane coupling agent (D), and the like Since the carboxyl group of the (meth) acrylate copolymer (A) reacts, the degree of aggregation of the first (meth) acrylate copolymer (A) can be adjusted, and the desired bondability can be obtained. In addition, when the decane coupling agent (D) is contained, for example, in a state in which the polarizing plate is bonded to the liquid crystal cell or the like, the adhesion between the adhesive and the liquid crystal glass cell is further improved.

The decane coupling agent (D) is an organic ruthenium compound having at least one alkoxycarbenyl group in the molecule, and has good compatibility with an adhesive component, and has light permeability, for example, substantially Suitable for transparency. The amount of the decane coupling agent (D) to be added is preferably 0.05 to 0.5 parts by mass, particularly preferably 0.1 to 0.3, per 100 parts by mass of the first (meth) acrylate copolymer (A). Parts by mass.

Specific examples of the decane coupling agent (D) include a polymerizable unsaturated fluorene compound such as vinyl trimethoxy decane, vinyl triethoxy decane, methacryl propyl propyl trimethoxy decane, and the like. - an epoxy structure oxime compound such as glycidoxypropyltrimethoxydecane or 2-(3,4-epoxycyclohexyl)ethyltrimethoxydecane, 3-aminopropyltrimethoxy Decane, N-(2-aminoethyl)-3-aminopropyltrimethoxydecane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxydecane, etc. An amine group-containing ruthenium compound, 3-apropyl propyl trimethoxy decane or the like. These may be used alone or in combination of two or more.

In the above-mentioned adhesive composition, various additives generally used for the propylene-based adhesive, such as an adhesion-imparting agent, an oxidation preventive agent, an ultraviolet absorber, a light stabilizer, a softener, a filler, and a charge can be added as required. Preventing agent, refractive index adjusting agent, and the like.

[Method of Manufacturing Adhesive Composition]

The above-mentioned adhesive composition can be produced, for example, as follows.

In other words, first, it is preferable to prepare the (meth) acrylate copolymers (A) and (B) by a usual radical polymerization method in each of the polymerization solvents described later. Next, a solution of the obtained two copolymers is mixed, and a diluted solvent is added so that the solid content concentration becomes 10 to 40% by mass. Finally, the crosslinking agent (C) and the decane coupling agent (D) are sequentially added, and the mixture is sufficiently mixed to obtain an adhesive composition diluted with a solvent.

Further, the above-mentioned adhesive composition is preferably produced by a series of polymerizations shown below.

Specifically, (1) the monomer constituting the first (meth) acrylate copolymer (A) is subjected to radical polymerization at a conversion ratio of 50 to 90% to produce the first (meth)acrylic acid. After the ester copolymer (A); (2) in the presence of the first (meth) acrylate copolymer (A), for the polymerization of the (meth) acrylate copolymer (A) remaining in the first The monomer and the monomer having the functional group (b1) having high reactivity with the crosslinking agent (C) and other monomers used as required, preferably having a conversion ratio of 70 to 100% Polymerization to produce the second (meth) acrylate copolymer (B), followed by (3) addition of a crosslinking agent (C) and/or a decane coupling agent (D) (component (D) is required).

The single system of the (meth) acrylate copolymer (A) constituting the first step of the process (1) is as described above, and it is preferred that the alkyl group having at least the ester moiety has a carbon number of 1 to 20 (methyl group). )Acrylate. In this state, in the process (2), the single system remaining in the polymerization of the first (meth) acrylate copolymer (A) is preferably a carbon number of the alkyl group of the ester moiety of 1 to 20 (A) Base) acrylate.

The above-mentioned series of polymerization systems can be carried out by a solution polymerization method or the like using a polymerization initiator as required. Examples of the polymerization solvent include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, and methyl ethyl ketone. Two or more types may be used in combination.

As the polymerization initiator, a azo group-based compound, an organic peroxide, or the like can be used in combination of two or more types. Examples of the azo-based compound series include 2,2'-azodiazobutyronitrile, 2,2'-azo (2-methylbutyronitrile), and 1,1'-azo (cyclohexane 1- Nitrile), 2,2'-azo (2,4-dimethylvaleronitrile), 2,2'-azo (2,4-dimethyl-4-methoxyvaleronitrile), dimethyl 2,2'-azo (2-methylpropionate), 4,4'-azo (4-cyanovaleric acid), 2,2'-azo (2-hydroxymethylpropionitrile), 2,2'-azo[2-(2-imidazolin-2-indene)propane] and the like.

As the series of organic peroxides, for example, benzoquinone peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate Ester, bis(2-ethoxyethyl)peroxydicarbonate, t-butyl peroxy neodecanoic acid, t-butyl peroxypivalate, (3,5,5-trimethylhexyl) Mercapto) peroxide, dipropyl hydrazine peroxide, diethyl hydrazine peroxide, and the like.

In the process (3), it is preferred to dilute the crosslinking agent (C) and the decane coupling agent (D) by a solvent in a state where both the crosslinking agent (C) and the decane coupling agent (D) are added. After the concentration is specified, it is added sequentially.

Further, in the foregoing series of polymerizations, the amount of each monomer used is appropriately adjusted so that the (meth) acrylate copolymer (A) and the (meth) acrylate copolymer (B) of the first The ratio and the content of the functional group are in the above range. Further, the polymerization conditions are appropriately adjusted so that the weight average molecular weight of the first (meth) acrylate copolymer (A) and the second (meth) acrylate copolymer (B) is in the above range.

[adhesive]

The adhesive of the present embodiment is composed by crosslinking the above-mentioned adhesive composition. The crosslinking of the aforementioned adhesive composition can be carried out by heat treatment. Further, the heat treatment system may be combined with a drying treatment at the time of volatilizing a solvent or the like of the adhesive composition.

In the state where the heat treatment is carried out, the heating temperature is preferably 50 to 150 ° C, particularly preferably 70 to 120 ° C. Further, the heating time is preferably from 30 seconds to 3 minutes, particularly preferably from 50 seconds to 2 minutes. Further, it is particularly preferable to set a curing period of about 1 to 2 weeks at room temperature (for example, 23 ° C, 50% RH) after the heat treatment.

By the above heat treatment (and curing), the second (meth) acrylate copolymer (B) is crosslinked by the crosslinking agent (C) to form a ternary mesh structure, and at the same time, in its ternary mesh structure The first (meth) acrylate copolymer (A) does not cause a direct chemical bond or is entangled by a very small number of chemical bonds. Further, in the state in which the (meth) acrylate copolymer (A) has a carboxyl group, the first (meth) acrylate copolymer (A) is reacted with the decane coupling agent (D) to a predetermined extent. Agglutination.

The adhesive agent described above is preferably used as an optical member, for example, for bonding of a polarizing plate and a phase difference plate or bonding of a polarizing plate (polarizing film) or a phase difference plate (retardation film) and a glass substrate. . The adhesive layer formed by the above-mentioned adhesive has very good stress relaxation property, so that the adhesive layer can be absorbed and viscous even in a state where the size of the adherend is greatly changed. Since the stress is generated due to the dimensional change, it is not easily peeled off by the adherend after a long period of time, and at the same time, when used in the optical member described above, light leakage can be effectively prevented. That is, the adhesive of the present embodiment achieves both light leakage resistance and durability.

[sticker]

As shown in Fig. 1, the pressure-sensitive adhesive sheet 1A of the first embodiment is formed by sequentially peeling the sheet 12 from the lower surface, laminating the adhesive layer 11 laminated on the release surface of the release sheet 12, and laminating the adhesive. The substrate 13 of the layer 11 is constructed.

Further, as shown in Fig. 2, the adhesive sheet 1B of the second embodiment is bonded to the two release sheets 12a by two release sheets 12a and 12b and two release sheets 12a and 12b. The adhesive layer 11 of the peeling surface of 12b is formed. In addition, the peeling surface of the peeling sheet of this specification is a surface which has a peeling property on a peeling sheet, and the surface which carried out the peeling process, and the surface which shows the peeling property, even if it is a peeling process.

Even in any of the adhesive sheets 1A and 1B, the pressure-sensitive adhesive layer 11 is composed of an adhesive composed of the above-mentioned adhesive composition.

The thickness of the pressure-sensitive adhesive layer 11 is appropriately determined in accordance with the purpose of use of the pressure-sensitive adhesive sheets 1A and 1B, but is usually in the range of 5 to 100 μm, preferably 10 to 60 μm, for example, as an optical member, particularly polarized light. In the state of the adhesive layer for a sheet, it is preferably 10 to 50 μm, particularly 10 to 30 μm.

The substrate 13 is not particularly limited, and any of the substrate sheets used as the usual adhesive sheet can be used. For example, in addition to the required optical member, a woven or non-woven fabric using fibers such as fluorene filament, acryl, or polyester; papers such as upper paper, cellophane, impregnated paper, and coated paper; aluminum, copper, etc. may be mentioned. Metal foil; foam of urethane foam, polyethylene foam, etc.; polyethylene terephthalate, polybutylene terephthalate, polyvinyl phthalate, etc. Polyester film, polyurethane film, polyethylene film, polypropylene film, polyvinyl chloride film, polyvinylidene chloride film, polyvinyl alcohol film, ethylene-vinyl acetate copolymer film, polystyrene film, A plastic film such as a polycarbonate film, an acrylic resin film, a raw spinel resin film, or a cycloolefin resin film; or a laminate of two or more of these. The plastic film system can perform one-axis extension or two-axis extension.

Examples of the optical member include a polarizing plate (polarizing film), a polarizer, a phase difference plate (retardation film), a viewing angle compensation film, a brightness enhancement film, and a contrast lifting film. In the case where the polarizing plate (polarizing film) is easily shrunk and the dimensional change is large, it is suitable for forming the pressure-sensitive adhesive layer 11 from the viewpoint of light leakage resistance.

The thickness of the base material 13 varies depending on the type thereof. However, in the state of the optical member, for example, it is usually 10 μm to 500 μm, preferably 50 μm to 300 μm.

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

It is preferable to perform a peeling treatment on the peeling surface of the peeling sheet (particularly, the surface joined to the pressure-sensitive adhesive layer 11). Examples of the release agent used in the release treatment include, for example, an alkyd type, an anthrone type, a fluorine type, an unsaturated polyester type, a polyolefin type, and a wax type release agent.

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

In order to manufacture the above-mentioned pressure-sensitive adhesive sheet 1A, a solution containing the above-mentioned adhesive composition is applied to the release surface of the release sheet 12, and after the heat treatment to form the pressure-sensitive adhesive layer 11, the adhesive layer 11 is applied thereto. , the substrate 13 is laminated. Further, as far as the conditions of the heat treatment are concerned, as described above.

Further, in order to manufacture the above-mentioned pressure-sensitive adhesive sheet 1B, a coating solution containing the above-mentioned adhesive composition is applied to the release surface of the release sheet 12a (or 12b) on one side, and heat treatment is performed to form an adhesive. After the layer 11, the release surface of the other side of the release sheet 12b (or 12a) is superposed on the adhesive layer 11.

The dilute solvent to be used as a coating solution for diluting the adhesive composition is, for example, an aliphatic hydrocarbon such as hexane, heptane or cyclohexane, an aromatic hydrocarbon such as toluene or xylene, or methylene chloride or the like. Halogenated hydrocarbon such as ethyl chloride, methanol, ethanol, propanol, butanol, 1-methoxy-2-propanol, alcohol, acetone, methyl ethyl ketone, 2-pentanone, isophorone And a ketone such as cyclohexanone, an ester such as ethyl acetate or butyl acetate, or a cellosolve solvent such as ethyl cellosolve.

The concentration ‧ viscosity of the coating solution prepared as described above may be a range that can be applied, and is not particularly limited, and may be appropriately selected depending on the state of the coating. For example, the concentration is made such that the concentration of 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 if the adhesive composition is a coatable viscosity or the like, the diluent solvent may not be added. In this state, the adhesive composition directly becomes a coating solution.

As a method of applying the coating solution, for example, a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, a gravure coating method, or the like can be used.

Here, for example, in order to manufacture a liquid crystal display device including a liquid crystal cell and a polarizing plate, a polarizing plate can be used as the base material 13 of the adhesive sheet 1A, and the release sheet 12 of the adhesive sheet 1A can be peeled off and bonded. The adhesive layer 11 and the liquid crystal cell are exposed.

Further, for example, in order to manufacture a liquid crystal display device in which a phase difference plate is disposed between the liquid crystal cell and the polarizing plate, the release sheet 12a (or 12b) on one side of the adhesive sheet 1B can be peeled off, and the exposed adhesive layer can be bonded. 11 and the liquid crystal cell, and then peeling off the peeling sheet 12b (or 12a) of the other side, bonding the exposed adhesive layer 11 and the phase difference plate, and peeling off the peeling sheet 12 of the adhesive sheet 1A using the polarizing plate, As the base material 13, the exposed adhesive layer 11 and the phase difference plate are bonded together.

According to the above adhesive sheets 1A, 1B, the adhesive layer 11 has very good stress relaxation property, and therefore, for example, even in a state suitable for bonding of polarizing plates, an adhesive can be used. The layer 11 absorbs and relaxes the stress which can be generated by the deformation of the polarizing plate, thereby exhibiting excellent light leakage resistance and high durability.

The embodiments described above are described in order to facilitate the understanding of the present invention, and are not intended to limit the present invention. Therefore, the various elements of the above-described embodiments are also intended to encompass all design changes or equivalents of the technical scope of the invention.

For example, the release sheet 12 of the adhesive sheet 1A may be omitted, and any of the release sheets 12a and 12b of the adhesive sheet 1B may be omitted.

[Examples]

In the following, the present invention will be more specifically described by way of examples, but the scope of the invention is not limited to the examples and the like.

[Example 1] 1. Process (1)

In a reaction vessel including a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen introduction tube, 97.0 parts by mass of n-butyl acrylate, 3.0 parts by mass of acrylic acid, 150.0 parts by mass of acetone, and 2,2'-azo two were charged. 0.06 parts by mass of nitrogen butyronitrile was substituted for the air in the reaction vessel by nitrogen. The mixture was stirred under the nitrogen atmosphere, and the reaction solution was heated to 60 ° C, and after cooling for 6 hours, it was cooled to room temperature. Here, GPC measurement was performed on a part of the obtained solution by the method described later, and the formation of the copolymer (A) having a weight average molecular weight of 1.5 million was confirmed. Further, the conversion ratio at this time (the mass of the copolymer obtained by polymerizing the monomer divided by the value of the total mass of the monomer used as the raw material) was 80%.

2. Process (2)

In the solution of the copolymer (A) obtained by the above process (1), 150 parts by mass of toluene, 2.2 parts by mass of 2-hydroxyethyl acrylate, and 2,2'-azo (2,4-dimethyl) are added. 0.50 parts by mass of valeronitrile was heated to 70 ° C, and after cooling for 6 hours, it was cooled to room temperature. Here, GPC measurement was again performed on a part of the obtained solution, and it was confirmed that almost no change occurred at the top of the peak of the weight average molecular weight of the copolymer (A) of 1.5 million, and by the result of the GPC measurement by this time, The result of the GPC measurement of the process (1) was subtracted, and the formation of a new copolymer (B) having a weight average molecular weight of 40,000 was confirmed. Ethyl acetate was added to the solution to obtain a propylene-based polymer solution (a solution of a mixture of the copolymer (A) and the copolymer (B)) having a solid content of 23.0% by mass. Here, the mixing ratio of the copolymer (A) and the copolymer (B) is a mass ratio of 80:20 because the conversion ratio of the above process (1) is 80%.

3. Process (3)

100 parts by mass of the solid content of the propylene-based polymer solution obtained by the above-mentioned process (2) was diluted with methyl ethyl ketone to obtain a solid content concentration of 20% by mass. Next, as the crosslinking agent (C), a phenylene diisocyanate (TDI) addition of trimethylolpropane in an amount equivalent to 1 equivalent of the hydroxyl group of the copolymer (B) is added (Japanese polyaminocarbamate B) Ester company, product name "Koronate L"). In the end, the decane coupling agent (D) was sufficiently stirred by adding 0.2 parts by mass of 3-glycidoxypropyltrimethoxydecane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBM403"). A diluted solution of the adhesive composition is obtained.

Here, the bonding 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.

[Copolymers (A) and (B)]

BA: n-butyl acrylate

AA: Acrylic

HEA: 2-hydroxyethyl acrylate

HBA: 4-hydroxybutyl acrylate

HEMA: 2-hydroxyethyl methacrylate

DEM: N,N-2-dimethylaminoethyl methacrylate

[Crosslinking agent (C)]

‧Isocyanate crosslinker

TDI: a phenylene diisocyanate addition of trimethylolpropane (manufactured by Japan Polyurethane Co., Ltd., trade name "Koronate L")

Isocyanate type: isocyanate of hexamethylene diisocyanate (manufactured by Japan Polyurethane Co., Ltd., trade name "Koronate HXR")

‧Other crosslinkers (epoxy crosslinkers)

N,N,N',N'-tetraepoxypropyl-m-phenylenedidimethyldiamine (manufactured by Mitsubishi Gas Chemical Co., Ltd., trade name "TETRAD-X")

[decane 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")

KBE403: 3-glycidoxypropyltriethoxydecane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBE403")

A diluting sheet for peeling treatment of a single side of a polyethylene terephthalate film by a ketone-based release agent in a diluted solution of the adhesive composition obtained by a doctor blade applicator (Lingteck) The peeling-treated surface of the company, SP-PET 3811, thickness: 38 μm) was allowed to have a thickness of 25 μm after drying, and then heat-treated at 90 ° C for 1 minute to form an adhesive layer.

Next, the adhesive layer and the discotic liquid crystal layer are bonded by laminating a polarizing plate composed of a polarizing film with a discotic liquid crystal layer and the polarizing film and the viewing angle expansion film are integrated, at 23 ° C, 50 The RH of % was maintained for 7 days, and a polarizing plate with an adhesive layer was obtained.

[Examples 2 to 34 and Comparative Examples 1 to 6]

In addition to adjusting the reaction conditions, the conversion ratio of the copolymer (A) was changed to the value of Table 1 and the addition amount of each monomer was changed so that the ratio of each monomer constituting the adhesive composition became the value of Table 1, and the others were A polarizing plate with an adhesive layer was produced in the same manner as in Example 1.

[Example 35]

The copolymer (A) having a weight average molecular weight of 1.5 million (GPC measurement) was obtained by copolymerizing 97 parts by mass of butyl acrylate and 3 parts by mass of acrylic acid by a usual polymerization method. Similarly, a copolymer (B) having a weight average molecular weight of 40,000 (measured by GPC) was obtained by copolymerizing 90 parts by mass of butyl acrylate and 10 parts by mass of 2-hydroxyethyl acrylate.

80 parts by mass of the obtained copolymer (A) and 20 parts by mass of the copolymer (B) were diluted with methyl ethyl ketone to have a solid concentration of 20% to obtain a propylene-based polymer solution. Then, a diluted solution of the adhesive composition was obtained in the same manner as in Example 1. Next, a polarizing plate with an adhesive layer was produced in the same manner as in Example 1 using the diluted solution of the adhesive composition.

[Test Example 1] (Measurement of Adhesion - Evaluation of Reworkability)

From the polarizing plate with the adhesive layer obtained in the examples or the comparative examples, a sample having a width of 25 mm and a length of 100 mm was cut out, the release sheet was peeled off, and the non-alkali was attached to the exposed adhesive layer. After the glass (made by Corning Co., Ltd., Eagle XG), the pressure cooker manufactured by Kurihara Seisakusho Co., Ltd. was pressurized at 0.5 MPa and 50 ° C for 20 minutes. Then, after standing for 24 hours under conditions of 23° C. and 50% RH, a tensile tester (Tensilon, manufactured by Orientec Co., Ltd.) was used, and according to JIS Z 0237, a peeling speed of 300 mm/min and a peeling angle of 180 degrees were used. To determine the adhesion (N/25mm).

Further, after standing for 14 days under conditions of 23 ° C and 50% RH, the adhesion was measured in the same manner as described above (adhesive force after 14 days of attachment; N/25 mm). Further, the range of the ideal adhesion is 0.1 N/25 mm or more and 25 N/25 mm is not full.

According to the adhesion force 14 days after the attachment, the evaluation of the reworkability was performed based on the following criteria. The results are shown in Table 2.

The adhesion after 14 days is 20N/25mm or less: ◎

The adhesion after 14 days is more than 20N/25mm, less than 25N/25mm: ○

After 14 days, the adhesion is 25N/25mm or more: ×

[Test Example 2] (Measurement of gel fraction)

A peeling sheet (SP-PET 3801, thickness: 38 μm, manufactured by Lingteck Co., Ltd.) which was subjected to a release treatment on one side of a polyethylene terephthalate film by an anthrone-based release agent was used instead of the example or the comparative example. An adhesive sheet was produced by using a polarizing plate made of a polarizing plate with an adhesive layer. Specifically, the release sheet was laminated on the adhesive layer having a thickness of 25 μm obtained in the examples or the comparative examples, and the release-treated surface side was joined to prepare a release sheet/adhesive layer/release sheet. Constructed as an adhesive sheet.

The obtained adhesive sheet was cured for 7 days under the conditions of 23 ° C and 50% RH. Then, the adhesive sheet was sampled to have a size of 80 mm × 80 mm, and the adhesive layer was packaged in a polyester mesh (mesh size 200), and only the quality of the adhesive was weighed by a precision balance. Take the quality at this time as M1.

A sample of the adhesive was immersed in an ethyl acetate solvent using a Soxhlet's reflux extractor, and refluxed for 16 hours. Then, the adhesive was taken out, air-dried for 24 hours in an environment of a temperature of 23 ° C and a relative humidity of 50%, and dried in an oven at 80 ° C for 12 hours. Only the quality of the dried adhesive is weighed by a precision balance. Take the quality at this time as M2. The gel fraction (%) is represented by (M2/M1) × 100. The results are shown in Table 2.

[Test Example 3] (Measurement of optical properties)

A peeling sheet (SP-PET 3801, thickness: 38 μm, manufactured by Lingteck Co., Ltd.) which was subjected to a release treatment on one side of a polyethylene terephthalate film by an anthrone-based release agent was used instead of the example or the comparative example. An adhesive sheet was produced by using a polarizing plate made of a polarizing plate with an adhesive layer. Specifically, the release sheet was laminated on the adhesive layer having a thickness of 25 μm obtained in the examples or the comparative examples, and the release-treated surface side was joined to prepare a release sheet/adhesive layer/release sheet. Constructed as an adhesive sheet.

The obtained adhesive sheet was cured for 7 days under the conditions of 23 ° C and 50% RH. Then, the turbidity value (%) was measured in accordance with JIS K7105 using a turbid meter (Nippon Denshoku Industries Co., Ltd., NDH2000) for the adhesive layer of the adhesive sheet. The results are shown in Table 2. Further, the ideal haze value ranges from 0 to 5%.

[Test Example 4] (Evaluation of durability)

The polarizing plate with the pressure-sensitive adhesive layer obtained in the examples or the comparative examples was adjusted to have a size of 233 mm × 309 mm by using a cutting device (a super cutter manufactured by Takino Seisakusho Co., Ltd., PN1-600). The peeling sheet was peeled off and attached to an alkali-free glass (Eagle XG, manufactured by Corning Co., Ltd.) through the exposed adhesive layer, and then subjected to an autoclave made by Kurihara Co., Ltd. at 0.5 MPa and 50 ° C for 20 minutes. Pressure.

Then, it was placed in an environment of the following durability conditions, and after 500 hours, observation was performed using a magnifying glass of 10 times. The change in appearance is based on the following. The results are shown in Table 2.

◎: On the 4 sides, no defects occur.

○: On the four sides, from the peripheral end to the portion of 0.6 mm or more, no defects occur.

X: At least one side of the four sides, from the peripheral end portion to a portion of 0.6 mm or more, there is an abnormality in the appearance of an adhesive having a thickness of 0.1 mm or more such as floating, peeling, foaming, or streaking.

<endurance condition>

‧ 60 ° C, relative humidity 90%

‧ 80 ° C, dry

[Test Example 5] (light leakage test)

The polarizing plate with the pressure-sensitive adhesive layer obtained in the examples or the comparative examples was adjusted to have a size of 233 mm × 309 mm by using a cutting device (a super cutter manufactured by Takino Seisakusho Co., Ltd., PN1-600). The peeling sheet was peeled off and attached to an alkali-free glass (Eagle XG, manufactured by Corning Co., Ltd.) through the exposed adhesive layer, and then subjected to an autoclave made by Kurihara Co., Ltd. at 0.5 MPa and 50 ° C for 20 minutes. Pressure. Further, the bonding is performed on the front surface of the alkali-free glass, and the polarizing plate with the adhesive layer is applied to make the polarizing axis into a state of orthogonal polarization (polarizing axis: ∠45°, ∠135°). In this state, after leaving to stand in a dry environment at 80 ° C for 500 hours, the light leakage property was evaluated by the method shown below. The results are shown in Table 2.

<Evaluation of light leakage>

The luminance of each region shown in FIG. 3 was measured using MCPD-2000 manufactured by Otsuka Electronics Co., Ltd. by the formula ΔL*=[(b+c+d+e)/4]-a (however, a, b, c, d, and e are the luminances of the predetermined measurement points (one portion of the central portion of each region) of the A region, the B region, the C region, the D region, and the E region, respectively, and the luminance difference ΔL* is obtained. As light leakage. The smaller the value of ΔL*, the less the light leakage is displayed.

Here, the weight average molecular weight is a polystyrene-equivalent weight average molecular weight measured by gel permeation chromatography (GPC) under the following conditions (GPC measurement).

<Measurement conditions>

‧ GPC measuring device: manufactured by TOSOH, HLC-8020

‧ GPC columns (passed in the following order): made by TOSOH

TSK guard column HXL-H

TSK gel GMHXL (×2)

TSK gel G2000HXL

‧ Determination of solvent: tetrahydrofuran

‧Measurement temperature: 40 ° C

It is apparent from Table 2 that the polarizing plate with the adhesive layer obtained in the examples is durable, has no problem, and has good light leakage resistance. Further, in Examples 1 to 30 in which the amount of introduction of acrylic acid in the copolymer (A) and the amount of addition of the crosslinking agent (C) were adjusted, the reworkability was also good, and the haze value was also suppressed to be lowered. With good transparency. Further, Example 1 obtained by a series of polymerizations to obtain a propylene-based polymer solution has good light resistance as compared with Example 35 in which the propylene-based polymer solution is obtained by the same blending and blending system. Leakage, turbidity value becomes lower.

In Comparative Example 1, the weight average molecular weight of the first (meth) acrylate copolymer (A) was excessively small, and thus durability and reworkability were deteriorated. In Comparative Example 2, since the content of the hydroxyl group of the (meth)acrylate copolymer (B) is excessively small, the gel fraction (degree of crosslinking) is lowered, and durability is deteriorated. In Comparative Example 3, the weight average molecular weight of the second (meth) acrylate copolymer (B) was excessively small, and thus the durability was deteriorated. In Comparative Example 4, the weight average molecular weight of the second (meth) acrylate copolymer (B) was excessively large, and thus durability and reworkability were deteriorated. In Comparative Example 5, since the content of the second (meth) acrylate copolymer (B) was excessively large, durability was deteriorated. In Comparative Example 6, since the content of the second (meth) acrylate copolymer (B) is excessively small, the gel fraction (degree of crosslinking) is lowered, and durability is deteriorated.

[Industrial Availability]

The adhesive composition and the adhesive of the present invention are suitable for bonding of an optical member such as a polarizing plate or a phase difference plate, and the adhesive sheet of the present invention is suitable for use as an optical member such as a polarizing plate or a phase difference plate. Adhesive sheet.

1A. . . Adhesive sheet

1B. . . Adhesive sheet

11. . . Adhesive layer

12. . . Peeling piece

12a. . . Peeling piece

12b. . . Peeling piece

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 a measurement area of a light leakage test of a polarizing plate with an adhesive layer.

1A. . . Adhesive sheet

11. . . Adhesive layer

12. . . Peeling piece

13. . . Substrate

Claims (13)

An adhesive composition comprising a first (meth) acrylate copolymer (A) having a weight average molecular weight of 700,000 to 2.5 million, and a second (meth) acrylate copolymer having a weight average molecular weight of 8,000 to 250,000. (B), a crosslinking agent (C), and a decane coupling agent (D), and the above-mentioned second (meth) acrylate copolymer (B) is compared with 100 parts by mass of the aforementioned first (meth)acrylic acid. The ratio of the ester copolymer (A) is 5 to 50 parts by mass, characterized in that the second (meth) acrylate copolymer (B) contains a high reactivity with the crosslinking agent (C). The monomer of the functional group (b1) is a structural component, and in the second (meth) acrylate copolymer (B), the copolymer is a copolymer having a ratio of the monomer of more than 1% by mass, and the first The (meth) acrylate copolymer (A) is a structural component which does not contain a functional group having a reactivity with the crosslinking agent (C), or contains the crosslinking agent (C) The monomer having a lower reactivity than the functional group (a1) of the functional group (b1) of the (meth) acrylate copolymer (B) is used as a structural component. The adhesive composition of the first aspect of the invention, wherein the first (meth) acrylate copolymer (A) does not contain a functional group having high reactivity with the crosslinking agent (C). The monomer is a structural component. The adhesive composition of the first aspect of the invention, wherein the functional group (a1) of the first (meth) acrylate copolymer (A) and the crosslinking agent (C) is low reactivity. a carboxyl group, a high reactivity of the aforementioned (meth) acrylate copolymer (B) and the aforementioned crosslinking agent (C) The functional group (b1) is a hydroxyl group, and the crosslinking agent (C) is an isocyanate crosslinking agent. The adhesive composition of the third aspect of the invention, wherein the first (meth) acrylate copolymer (A) contains 0 to 15% by mass of the carboxyl group-containing monomer as a single constituting the copolymer. Body unit. The adhesive composition of the third aspect of the invention, wherein the second (meth) acrylate copolymer (B) contains 3 to 40% by mass of the hydroxyl group-containing monomer as a single constituting the copolymer. Body unit. The adhesive composition of the third aspect of the invention, wherein the content of the isocyanate crosslinking agent is an isocyanate group of the isocyanate crosslinking agent relative to the second (meth) acrylate copolymer (B) The amount of the functional group (b1) having a high reactivity with the crosslinking agent (C) is 0.1 to 5 equivalents. The adhesive composition of the first aspect of the invention, wherein the content of the decane coupling agent (D) is 0.05 based on 100 parts by mass of the first (meth) acrylate copolymer (A). ~0.5 parts by mass. A method for producing an adhesive composition, which comprises the adhesive composition according to claim 1, which comprises a conversion ratio of 50 to 90% for copolymerization of the first (meth) acrylate constituting the first The monomer (A) is subjected to radical polymerization to produce the first (meth) acrylate copolymer (A) (1); and the first (meth) acrylate copolymer (A) In the presence of Free radicals are present in the monomer remaining in the polymerization of the first (meth) acrylate copolymer (A) and the monomer having the high reactivity with the crosslinking agent (C) (b1) Copolymerization, the process (2) for producing the second (meth) acrylate copolymer (B); the process (3) of adding the crosslinking agent (C); and the addition of the decane coupling agent (D) Process. The method for producing an adhesive composition according to the eighth aspect of the invention, wherein the process (2) for producing the second (meth) acrylate copolymer (B) has a conversion ratio of 70 to 100%, Free radicals are present in the monomer remaining in the polymerization of the first (meth) acrylate copolymer (A) and the monomer having the high reactivity with the crosslinking agent (C) (b1) Copolymerization. An adhesive composition comprising the adhesive composition according to any one of claims 1 to 7 of the invention. An adhesive sheet comprising a substrate and an adhesive layer, wherein the adhesive layer is composed of the adhesive according to claim 10 of the patent application. The adhesive sheet of claim 11, wherein the substrate is an optical member. An adhesive sheet comprising two release sheets and an adhesive layer sandwiched between the release sheets and bonded to the release faces of the two release sheets, wherein the adhesive layer is the patent application number 10 Adhesive Composition.