TWI527864B - Adhesive compositions, adhesives, and adhesive sheets - Google Patents

Description

Adhesive composition, adhesive and adhesive sheet

The present invention relates to an adhesive composition, an adhesive (a material obtained by crosslinking an adhesive composition), and an adhesive sheet, particularly an adhesive composition and an adhesive for an optical member suitable for a polarizing plate or the like. And sticky sheets.

In the liquid crystal panel, when the polarizer and the retardation film are bonded to a glass substrate of a liquid crystal cell or the like, an adhesive layer formed of an adhesive composition is often used. However, an optical member such as a polarizing plate or a retardation plate is easily contracted by heat or the like, and shrinkage due to the above thermal change occurs. As a result, the adhesive layer stacked on the optical member cannot follow the shrinkage. Therefore, peeling occurs at the interface (so-called floating, peeling), and the stress at the time of shrinkage of the optical member causes the optical axis of the optical member to deviate, thereby causing light leakage (so-called white spot).

(1) A method in which an adhesive layer having a high adhesive force and excellent form stability is bonded to an optical member such as a polarizing plate, and shrinkage of the optical member is suppressed by itself, or (2) A method of using an adhesive layer having a small stress when shrinking an optical member. As the method of (1), it is effective to use an adhesive layer having a high storage modulus as shown in Patent Document 1. On the other hand, as the method of (2), it is effective to use an adhesive layer which is excellent in the stress relaxation rate which can soften the deformation of the optical member. However, in the past, the use of such stress In the case of an adhesive layer having a good relaxation ratio, it is necessary to set the crosslinking density in the adhesive layer to be low. However, this causes a problem that the strength of the adhesive layer itself is deteriorated and the durability is deteriorated.

Therefore, in Patent Document 2-4, a plasticizer, a fluid paraffin, a polyurethane elastomer, or the like is added to an acrylic adhesive without setting the crosslinking density of the adhesive layer to be low, and the obtained adhesive composition has a moderate degree. The softness imparts a stress relaxation rate to the adhesive layer, thereby obtaining light leakage resistance and durability.

However, the adhesive layer formed by the plasticizer or the fluid paraffin-added adhesive composition bleeds out over time with the plasticizer and the flowing paraffin. As a result, the adhesion durability is deteriorated, and various problems such as contamination of the liquid crystal cell of the adherend are worried. Further, in the adhesive composition to which the polyurethane elastomer is added, if the compatibility is maintained, the addition amount of the polyurethane elastomer is increased, but the upper limit is limited. Therefore, in the adhesive layer obtained from the above adhesive composition, the improvement in the stress relaxation rate is insufficient. Further, in order to increase the stress relaxation rate, it is necessary to increase the amount of the polyurethane elastomer to be added, which causes a problem that the compatibility with the acrylic pressure-sensitive adhesive is deteriorated, and white turbidity or the like occurs. As described above, in the prior art, it is difficult to fundamentally improve the light leakage resistance and durability of the adhesive layer formed of the adhesive composition for optical components.

However, the release sheet on which the above-mentioned adhesive layer is laminated, or the optical member such as a polarizing plate and a phase difference plate are usually made of a plastic material. Therefore, when electrical insulation is high and the peeling sheet is peeled off, static electricity is likely to occur. In the state where the static electricity thus generated remains, such as a polarizer and When a phase difference plate or the like is bonded to the liquid crystal cell, the alignment of the liquid crystal molecules may be disturbed, and the presence of static electricity may cause problems such as dust.

Therefore, it has been proposed to add a charge preventing agent to the adhesive composition in order to obtain the charging prevention performance effectively (for example, Patent Documents 5 to 8).

[Patent Literature]

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

[Patent Document 2] Japanese Patent Publication No. 5-45517

[Patent Document 3] Japanese Patent Publication No. 9-137143

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

[Patent Document 5] JP-A-2005-290357

[Patent Document 6] JP-A-2007-316377

[Patent Document 7] JP-A-2008-95081

[Patent Document 8] JP-A-2009-155585

However, when a charge inhibitor is added to the adhesive composition, the durability of the obtained adhesive is less than usual. In the above-mentioned adhesive, in order to impart a stress relaxation rate, the crosslinking density is lowered, and a plasticizer or the like is added, but the durability is further deteriorated as described above. Therefore, it is more difficult to impart a stress relaxation rate. As described above, in the adhesive having electrical preventive property, both the stress relaxation rate and the durability in an inverse proportional relationship are problems.

The present invention has been completed in view of such actual conditions. this invention An object of the present invention is to provide an adhesive composition, an adhesive, and an adhesive sheet which are excellent in both stress relaxation rate and durability when used in an optical member such as a polarizing plate.

In order to achieve the above object, the present invention is as follows: First, the present invention provides an adhesive composition comprising a first (meth) acrylate polymer having a weight average molecular weight of 500,000 to 3,000,000 (A). a second (meth) acrylate polymer (B) having a weight average molecular weight of 8,000 to 300,000, a crosslinking agent (C), and a charge preventing agent (D) for polymerizing the above first (meth) acrylate 100 parts by mass of the material (A), the ratio of the second (meth) acrylate polymer (B) is 5 to 50 parts by mass, and the second (meth) acrylate polymer (B) is contained as a constituent component. a monomer having a functional group (b1) reactive with the above crosslinking agent (C), and further a ratio of a monomer having the above functional group (b1) to the above second (meth) acrylate polymer (B) When the amount exceeds 1% by mass and the content is less than 50% by mass, the first (meth) acrylate polymer (A) does not contain a monomer having a functional group reactive with the crosslinking agent (C) as a constituent component. Or the component contains a lower reactivity with the crosslinking agent (C) than the functional group (b1) of the second (meth)acrylate polymer (B). Monomer of functional group (a1) (Invention 1).

The adhesive obtained by crosslinking the adhesive composition of the invention (Invention 1) can exhibit charge prevention, suitable cohesive force, and excellent stress relaxation rate. By using the above-mentioned optical member having an excellent stress relaxation rate, it is possible to obtain sufficient charge prevention property when used in an optical member such as a polarizing plate, and it is excellent in both light leakage resistance and durability. Adhesive tablets.

In the above invention (Invention 1), the first (meth) acrylate polymer (A) or the first (meth) acrylate polymer (A) and the second (meth) acrylate polymer (B), the constituent unit unit of the above polymer preferably contains 5 to 50% by mass of the alkylene oxide monomer (Invention 2).

In the above invention (Inventions 1 and 2), the above-mentioned charge preventing agent (D) is preferably an ionic compound (Invention 3).

In the above invention (Invention 3), the ionic compound is preferably at least 1 selected from the group consisting of a nitrogen-containing phosphonium salt, a sulfur-containing phosphonium salt, a phosphorus-containing phosphonium salt, an alkali metal salt, and an alkaline earth metal salt. (Invention 4).

In the above invention (Invention 4), at least one selected from the group consisting of the alkali metal salt, the lithium salt, and the potassium salt is preferred (Invention 5).

In the above invention (Invention 1-5), the functional group (a1) in the first (meth) acrylate polymer (A) is a carboxyl group, and the second (meth) acrylate polymer (B) The functional group (b1) is a hydroxyl group, and the crosslinking agent (C) is an isocyanate crosslinking agent (Invention 6).

In the above invention (Invention 1-5), the first (meth) acrylate polymer (A) does not contain a carboxyl group-containing monomer as a constituent monomer, or contains a carboxyl group-containing monomer as the functional group (a1). The mass % or less is preferable (Invention 7).

In the above invention (Invention 1-7), it is preferred that the second (meth) acrylate polymer (B) contains 3 to 40% by mass of the hydroxyl group-containing monomer as the functional group (b1) (Invention 8).

In the above invention (Invention 6), the content of the isocyanate crosslinking agent is such that the isocyanate group of the isocyanate crosslinking agent is the functional group (b1) in the second (meth) acrylate polymer (B). An amount of from 0.1 to 3.5 equivalents is preferred (Invention 9).

Secondly, the present invention provides an adhesive in which the above-mentioned adhesive composition (Invention 1-9) is crosslinked (Invention 10).

In the above invention (Invention 10), the surface resistivity of the above-mentioned adhesive is preferably 3.0 × 10 ¹¹ Ω/sq or less (Invention 11).

According to a third aspect of the invention, there is provided an adhesive sheet comprising a substrate and an adhesive layer, wherein the adhesive layer is composed of the adhesive (Inventions 10 and 11) (Invention 12).

In the above invention (Invention 12), the substrate is preferably an optical member (Invention 13).

According to a fourth aspect of the invention, in the adhesive sheet having two release sheets and the release sheet, the adhesive sheet is in contact with the release surface of the two release sheets, and is characterized in that the adhesive is The agent layer is composed of the above-mentioned adhesive (Inventions 10 and 11) (Invention 14).

Among the adhesives obtained by crosslinking the adhesive composition of the present invention, conventionally, a low molecular weight polymer used as a plasticizer forms a three-dimensional network structure having a chemical crosslinked structure, and the three-dimensional network structure has a plurality of High molecular weight polymer insertion, high molecular weight polymers are bound, and high molecular weight polymers form a pseudo-crosslinked structure (presumed). Thereby, the obtained adhesive can exhibit appropriate agglutination while having charge prevention property. Force and excellent stress relaxation rate. By applying the above-described adhesive having an excellent stress relaxation rate to an optical member such as a polarizing plate, it is possible to exhibit sufficient charge prevention and obtain excellent adhesion both to light leakage resistance and durability. sheet.

Hereinafter, embodiments of the present invention will be described.

[adhesive composition]

The adhesive composition of the present embodiment contains a first (meth) acrylate polymer (A) having a weight average molecular weight (Mw) of 500,000 to 3,000,000 and a second weight average molecular weight (Mw) of 8,000 to 300,000. The (meth) acrylate polymer (B), the crosslinking agent (C), and the charge prevention agent (D) preferably further contain a decane coupling agent (E). In the present specification, the term "(meth)acrylate" means both acrylate and methacrylate. The same is true for other similar terms. In addition, "polymer" also contains the concept of "copolymer".

In the adhesive obtained by crosslinking the above adhesive composition, the second (meth) acrylate polymer (B) (low molecular weight polymer) forms a three-dimensional network structure in the cross-linking agent (C), in the above three-dimensional In the network structure, the first (meth) acrylate polymer (A) (high molecular weight polymer) is not more than 2 molecules, and is not directly accompanied by a chemical bond, or is accompanied by a very small chemical bond insertion, and the polymer (A) has A state of some degree of freedom is formed (presumed) by a bound pseudo-crosslinked structure (so-predicted structure, hereinafter referred to as "construct X"). The adhesive having the above structure X has charge prevention property, Appropriate agglutination and excellent stress relaxation rate can be exerted. The optical member having such an excellent stress relaxation rate is excellent in durability while being excellent in light leakage resistance, and is excellent in durability, and can prevent floating and peeling under conditions such as high temperature.

The above (meth) acrylate polymer (A) or (B) is preferably an alkyl (meth) acrylate having a carbon number of 1 to 20 and a monomer having an alkoxide moiety (including a sub a copolymer of an alkoxy monomer), a monomer having a functional group reactive with the crosslinking agent (C) (containing a reactive functional group monomer), and another monomer used as needed. Further, the first (meth) acrylate polymer (A) preferably does not contain the above-mentioned reactive functional group-containing monomer as a constituent unit. Further, the second (meth) acrylate polymer (B) preferably contains the above-mentioned alkylene group-containing monomer as a constituent unit.

The (meth)acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group may, for example, be methyl (meth)acrylate, ethyl (meth)acrylate or propyl (meth)acrylate. N-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, Isooctyl (meth)acrylate, n-aryl (meth)acrylate, n-dodecyl (meth)acrylate, myristyl (meth)acrylate, hexadecane (meth)acrylate A base ester and a stearyl (meth) acrylate. These may be used alone or in combination of two or more.

The first (meth) acrylate polymer (A), as a constituent unit, preferably has an alkyl group having a carbon number of 1 to 20 and an alkyl (meth) acrylate content of 5 to 100% by mass. Jia is 30-90% by mass, more preferably There are 40-80% by mass. The content of the alkyl (meth)acrylate is in the range of 5 to 100% by mass, and a desired adhesiveness can be obtained. Further, the content of the alkyl (meth)acrylate is in the range of 30 to 90% by mass, and the content of the alkylene group-containing monomer and the reactive functional group-containing monomer in the polymer (A) can be ensured. the amount.

Further, the second (meth) acrylate polymer (B) is preferably a component of the alkyl group having 5 to 99% by mass of an alkyl (meth) acrylate having an alkyl group of 1 to 20% by mass. It is contained in an amount of 30 to 90% by mass, more preferably 40 to 80% by mass. The content of the alkyl (meth)acrylate is in the range of 5 to 99% by mass, and the desired adhesiveness can be obtained while ensuring the reactive functional group-containing monomer in the polymer (B). Containing amount. Further, when the content of the alkyl (meth)acrylate is in the range of 30 to 90% by mass, the content of the alkylene group-containing monomer in the polymer (B) can be ensured.

As the oxyalkyl group-containing monomer, 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2-methyl (meth) acrylate can be preferably exemplified. Oxypropyl propyl ester, 3-methoxypropyl (meth) acrylate, 2-methoxybutyl (meth) acrylate, 4-methoxybutyl (meth) acrylate, etc. Alkyl methacrylate. More preferably, it is a (meth)acrylic acid alkoxy ester of a polyalkylene glycol chain of a polyethylene glycol chain or a polypropylene glycol chain which has a terminal alkoxy group. Among them, 2-methoxyethyl (meth)acrylate is particularly preferable from the viewpoint of excellent compatibility of each monomer in the polymerization of the polymer (A) or (B). These may be used alone or in combination of two or more.

Containing an alkyleneoxy monomer, preferably at the first (meth) acrylate The polymer (A) alone or the first (meth) acrylate polymer (A) and the second (meth) acrylate polymer (B) are contained as constituent units. In this case, at least the first (meth) acrylate polymer (A) contains an alkylene oxide-containing monomer as a constituent unit, and the alkoxy group which exhibits hydrophilicity can improve the generation of the antistatic agent (D). Live to prevent performance. Thereby, the content of the antistatic agent (D) in the adhesive composition of the present embodiment can be reduced. Further, when only the second (meth) acrylate polymer (B) contains an alkylene oxide-containing monomer as a constituent unit, the three-dimensional network obtained from the polymer (B) and the crosslinking agent (D) During the formation of the structure, the difference in polarity between the three-dimensional network structure portion and the polymer (A) is increased (presumed). Thus, there is a possibility that the optical characteristics are deteriorated due to the phase separation of the two components, or the above-described structure X cannot be sufficiently formed. Therefore, it is best to avoid this approach.

The first (meth) acrylate polymer (A) preferably contains, as a constituent unit, 5 to 50% by mass of the above alkylene group-containing monomer, particularly preferably 10 to 40% by mass, more preferably 15%. 35 mass%. The same applies to the case where the second (meth) acrylate polymer (B) contains an alkylene oxide-containing monomer as a constituent unit. When the content of the alkylene oxide-containing monomer is within the above range, the above-mentioned excellent effects can be obtained, and the above-mentioned (meth)acrylic acid alkyl ester and reactive functional group in the adhesive composition of the present embodiment can be ensured. The content of the base monomer.

On the other hand, as the reactive functional group-containing monomer, a monomer having a hydroxyl group in the molecule (hydroxy group-containing monomer), a carboxyl group-containing monomer (carboxy group-containing monomer), and an amino group in the molecule can be preferably exemplified. Monomer (containing amino monomer) Wait. Further, the monomer containing the reactive functional group (a1) described below, the monomer containing the reactive functional group (b1), and the monomer containing the reactive functional group (b2) are reactive functional groups described herein. monomer. The selection of specific types will be described in each individual item.

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

The carboxyl group-containing monomer may, for example, be an olefinically 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-butylaminoethyl (meth)acrylate. They may be used alone or in combination of two or more.

Further, examples of the other monomer include an aliphatic ring-containing (meth)acrylate such as cyclohexyl (meth)acrylate and an aromatic ring such as phenyl (meth)acrylate ( Non-crosslinkable (meth)acrylamide such as methyl)acrylate, acrylamide, and methacrylamide; N,N-dimethylaminoethyl (meth)acrylate, (meth)acrylic acid N a non-crosslinkable (meth) acrylate having a tertiary amino group such as N-dimethylaminopropyl ester; vinyl acetate; styrene or the like. They may be used alone or in combination of two or more.

The second (meth) acrylate polymer (B) has a monomer (a monomer having a reactive functional group (b1)) having a functional group (b1) reactive with the crosslinking agent (C) as a constituent component. . The functional group contained in the above polymer (B) which can react with the crosslinking agent (C) is preferably substantially only the functional group (b1). Further, the phrase "substantially only the functional group (b1)" means that the amount of other functional groups which may be contained in the reaction with the crosslinking agent (C) is not hindered by the functional group (b1) and the crosslinking agent (C). The degree of reactivity.

In other words, the second (meth) acrylate polymer (B) preferably contains no functional group having a lower reactivity with the crosslinking agent (C) than the functional group (b1) as a constituent component. a monomer of (b2) (containing a reactive functional group (b2) monomer). However, when the reactive functional group (b2) monomer is contained as a constituent component, the mass ratio is 1/5 or less, particularly 1/10, of the content of the reactive functional group (b1)-containing monomer. The following quantities are preferred.

Further, the reactive functional group (b1)-containing monomer and the reactive functional group-containing (b2) monomer used in the second (meth) acrylate polymer (B), and the first (meth)acrylic acid described below The selection of the reactive functional group (a1)-containing monomer used in the ester polymer (A) is determined by the relationship with the reactivity of the crosslinking agent (C) to be used. The details are as follows.

The second (meth) acrylate polymer (B) contains the reactive functional group (b2) monomer in an amount such that the mass ratio exceeds 1/5 of the content of the reactive functional group (b1)-containing monomer. The durability of the obtained adhesive layer may be deteriorated. If the reactive functional group (b2) in the second (meth) acrylate polymer (B) is too much, the three-dimensional network structure formed thereby will be When the reactive functional group (b2) remains in a large amount, the compatibility of the three-dimensional network structure and the first (meth)acrylate polymer (A) changes (presumed). As a result, there is a case where the haze value rises. Further, the three-dimensional network structure in which a large amount of the reactive functional group (b2) remains, the mobility of the first (meth) acrylate polymer (A) inserted into the three-dimensional network structure is excessively restricted (presumed). As a result, the obtained stress relaxation rate of the adhesive is deteriorated, and the durability is deteriorated.

Further, when the adhesive composition of the present embodiment contains the decane coupling agent (E), the decane coupling agent (E) and the reactive functional group of the first (meth) acrylate polymer (A) described below ( A1) (particularly a carboxyl group) acts to bond with the high molecular weight first (meth) acrylate polymer (A). In addition, the bond referred to herein is not limited to a covalent bond, but also includes hydrogen bonding, hydrophobic interaction, and the concept of van der Waals. Thereby, the alkoxy fluorenyl moiety of the decane coupling agent (E) acts on the glass substrate, so that the obtained adhesive improves the adhesion to the glass substrate or the like of the adherend (presumed). Here, the second (meth) acrylate polymer (B) is excessively contained in the reactive functional group (b2) monomer, the decane coupling agent (E), and the second (meth) acrylate polymer (B). The reactive functional group (b2) (especially a carboxyl group) acts to bond with the low molecular weight second (meth) acrylate polymer (B), thereby being deprived of the bonding with the adherend ( Speculated). As a result, the adhesion between the obtained adhesive and the glass substrate to be bonded is deteriorated, whereby the durability of the adhesive layer may be deteriorated.

In the second (meth) acrylate polymer (B), the amount of the reactive functional group-containing (b1) monomer is more than 1% by mass, and the upper limit is 50% by mass. Not full. Preferably, the monomer containing the reactive functional group (b1) contains 5 to 40% by mass, particularly preferably 10 to 30% by mass, more preferably 12 to 20% by mass. When the reactive functional group (b1)-containing monomer is in the above range, the degree of crosslinking of the second (meth) acrylate polymer (B) is improved, and the first (meth) acrylate polymer (A) In the combination of the above, the stress relaxation rate of the obtained adhesive can be improved. As a result, an adhesive excellent in both durability and light leakage resistance was obtained. In addition, when the content of the reactive functional group-containing (b1) monomer is at most 1% by mass, the crosslinking of the second (meth) acrylate polymer (B) is insufficient, and the gel fraction is low. Durability may be worse. On the other hand, the content of the reactive functional group-containing (b1) monomer is 50% by mass or more, and the crosslinking of the second (meth) acrylate polymer (B) is excessive, and the stress relaxation rate is deteriorated. possibility. Further, when the upper limit of the content of the reactive functional group-containing (b1) monomer is 30% by mass, the light leakage resistance of the obtained pressure-sensitive adhesive sheet becomes more excellent.

Here, the second (meth) acrylate polymer obtained by polymerizing a monomer having an alkyl group having a carbon number of 1 to 20 and an alkyl group having a functional group reactive with the crosslinking agent (C) The polymerization method of (B) may be a random copolymer or a block copolymer.

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

The weight average molecular weight of the second (meth) acrylate polymer (B) is from 8,000 to 300,000, preferably from 10,000 to 200,000, particularly preferably from 50,000 to 100,000. That is, the second (meth) acrylate polymer (B) is a low molecular weight polymer component. In addition, the weight average molecular weight in this specification uses gel permeation chromatography. The polystyrene-converted value measured by the (GPC) method.

When the weight average molecular weight of the second (meth) acrylate polymer (B) is within the above range, a three-dimensional network structure peculiar to the adhesive composition of the present embodiment is formed, and there is an excellent stress relaxation rate. contribution. That is, if the weight average molecular weight of the second (meth) acrylate polymer (B) is less than 8,000, 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) exceeds 300,000, the compatibility with the first (meth) acrylate polymer (A) or the like is deteriorated, and adhesion is caused. The haze value of the agent layer may rise, and the optical characteristics may deteriorate. Further, the insertion of the polymer (A) into the three-dimensional network structure formed of the polymer (B) is insufficient, and as a result, the durability and reusability of the obtained adhesive are deteriorated. .

The first (meth) acrylate polymer (A) preferably contains a monomer having a functional group reactive with the crosslinking agent (C) as a constituent component, or contains a second component as a constituent component (a) a monomer (containing a reactive functional group (a1) monomer) having a functional group (a1) having a lower reactivity with the crosslinking agent (C) of the above-mentioned functional group (b1) of the methyl acrylate polymer (B) Therefore, it is particularly preferable that the monomer having a functional group having reactivity higher than the functional group (b1) and having a reactivity with the crosslinking agent (C) is contained as a constituent component.

The first (meth) acrylate polymer (A) may not contain a monomer having a functional group reactive with the crosslinking agent (C). However, if a reactive functional group (a1) monomer is contained, it is preferred. That is, the above polymer (A) contains a reactive functional group (a1) and promotes the second (meth) acrylate. The reaction of the polymer (B) with the crosslinking agent (C). Or, when the decane coupling agent (E) is used, the reactive functional group (a1) of the first (meth) acrylate polymer (A) and the decane coupling agent (E) described above act to obtain the obtained adhesive. The adhesion durability to the glass surface of the liquid crystal cell or the like is further improved, so that it is preferable.

When the first (meth) acrylate polymer (A) contains the above-mentioned reactive functional group (a1)-containing monomer, the content thereof is usually 20% by mass or less, preferably 15% by mass or less, particularly 10% by mass. % below is better. When the content of the reactive functional group-containing (a1) monomer is more than 20% by mass, the glass transition temperature (Tg) of the first (meth) acrylate polymer (A) becomes too high, and the obtained adhesive is The stress relaxation rate is likely to vary. Moreover, from the viewpoint of imparting reusability to the adhesive, the content of the reactive functional group-containing (a1) monomer is preferably 15% by mass or less.

Further, the reactive functional group contained in the first (meth) acrylate polymer (A) is compared with the reactive functional group (b1)-containing monomer contained in the second (meth) acrylate polymer (B). The ratio of the monomer (a1) monomer in the above first (meth) acrylate polymer (A) is preferably a reactive functional group contained in the second (meth) acrylate polymer (B) ( The ratio of the b1) monomer in the above second (meth) acrylate polymer (B) is small. Thereby, the reaction of the reactive functional group (a1) and the crosslinking agent (C) contained in the first (meth) acrylate polymer (A) is suppressed, and the second (meth) acrylate polymer can be made ( B) The reactive functional group (b1) and the crosslinking agent (C) contained are subjected to a definite reaction. Thereby, the stress relaxation rate of the obtained adhesive can be improved.

The first (meth) acrylate polymer (A) preferably does not contain a reactive functional group having a reactivity with the crosslinking agent (C) as the second (meth) acrylate polymer (B) in the molecule. The group (b1) is equal to or higher than the functional group. However, in the case where it is contained, the content of the monomer contained in the molecule is preferably 1% by mass or less, particularly preferably 0.5% by mass or less, based on the polymer (A). When the content of the above monomer is more than 1% by mass, the reaction of the second (meth) acrylate polymer (B) and the crosslinking agent (C) which are preferably carried out is likely to be inhibited. As a result, there is a case where the desired stress relaxation rate is not obtained.

Here, the alkyl (meth)acrylate having an alkyl group having a carbon number of 1 to 20 and a reactive functional group-containing monomer are polymerized to obtain a first (meth) acrylate polymer (A). The polymerization method can also be a random copolymer, and a block copolymer can also be used.

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

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

When the weight average molecular weight of the first (meth) acrylate polymer (A) is within the above range and the polymer (A) has a relatively large molecular weight, the structure X can be favorably formed (presumed).

Here, if the weight average molecular weight of the first (meth) acrylate polymer (A) is less than 500,000, and the obtained adhesive has a low gel fraction, there will be Durability and the possibility of poor reusability. In addition, the weight average molecular weight of the first (meth) acrylate polymer (A) exceeds 3 million, and the compatibility with the second (meth) acrylate polymer (B) or the like is deteriorated, and the stress of the obtained adhesive is increased. The slack rate has the possibility of getting worse.

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 preferable to use 10-30 parts by mass.

The above-described structure X can be favorably formed from the adhesive obtained by the adhesive composition containing the first (meth) acrylate polymer (A) and the second (meth) acrylate polymer (B) in the above ratio ( Speculated).

The crosslinking agent (C) is preferably an isocyanate crosslinking agent, an epoxy crosslinking agent, an aziridine crosslinking agent, a metal complexing compound crosslinking agent or the like.

The isocyanate crosslinking agent is a material containing at least a polyisocyanate compound. The polyisocyanate compound may, for example, be an aromatic polyisocyanate such as toluene diisocyanate, diphenylmethane diisocyanate or p-xylylene diisocyanate; or an aliphatic polyisocyanate such as hexamethylene diisocyanate; isophorone; Alicyclic isocyanate and alicyclic polyisocyanate such as hydrogenated diphenylmethane diisocyanate, and their biuret and isocyanurate bodies, further with ethylene glycol, propylene glycol, neopentyl glycol, and the like An adduct of a compound containing a low molecular weight active hydrogen such as methylolpropane or castor oil. Among them, toluene diisocyanate (TDI-based) adduct of trimethylolpropane is particularly preferable in order to impart moderate rigidity and flexibility to the obtained crosslinked structure.

As the epoxy-based crosslinking agent, 1,3-double (N, N'-dicondensation can be exemplified Glycidyl ether aminomethyl)cyclohexane, N,N-,N',N'-tetraglycidyl ether m-p-xylylenediamine, ethylene glycol diglycidyl ether, 1,6 - Hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidyl ether aniline, diglycidyl ether amine, and the like.

The aziridine-based crosslinking agent may, for example, be diphenylmethane 4,4'-bis(1-aziridine carboxamide), trimethylolpropane tri-β-aziridine propionate or tetramethylol group. Methane tri-β-aziridine propionate, toluene 2,4-bis(1-aziridine carboxamide), triethylene melamine, bis-m-phenylenedimethyl 1-(2-methylaziridine), three 1-(2-methylaziridine)phosphine, trimethylolpropane tri-β-(2-methylaziridine) propionate, and the like.

Among the metal complex compound-based crosslinking agents, the metal atom is a complex compound of aluminum, zirconium, titanium, zinc, iron, and tin, but an aluminum complex compound is preferable from the viewpoint of performance. As the aluminum complex compound, for example, diisopropoxy aluminum monooleyl acetoacetate, monoisopropoxy aluminum bis oleyl acetoacetate, monoisopropoxy aluminum monooleate monoethyl acetyl b An acid ester, aluminum diisopropoxide, monolauryl acetoacetate, diisopropoxy aluminum monostearyl acetoacetate, diisopropoxy aluminum monoisostearyl acetoacetate, and the like.

The content of the crosslinking agent (C) is such that the crosslinkable group (for example, an isocyanate group) of the above crosslinking agent (C) is reactive with the second (meth) acrylate polymer (B) ( The amount of b1) (e.g., a hydroxyl group) is usually an amount of from 0.05 to 5 equivalents, preferably from 0.1 to 3.5 equivalents, particularly preferably from 0.3 to 1.0 equivalents. When the amount of the crosslinkable group is less than 0.05 equivalent, the obtained gel has a low gel fraction and may not sufficiently exhibit a cohesive force. Further, the amount of the crosslinkable group is 0.1 equivalent or more, In particular, when the amount is 0.3 equivalent or more, the obtained adhesive can further improve durability. On the other hand, when the amount of the crosslinkable group is 3.5 equivalent or less, the obtained adhesive can be excellent in reusability. Further, when the amount of the crosslinkable group is 1.0 equivalent or less, the crosslinking agent (C) can contribute only to the formation of the three-dimensional network structure of the polymer (B), and the polymer (A) can be effectively prevented. Cross-linking (presumed). As a result, the obtained adhesive has excellent stress relaxation rate.

Further, in the present embodiment, as the crosslinking agent (C), the reactive functional group (b1) and the first (meth) acrylate polymer with the second (meth) acrylate polymer (B) ( When the relationship between the reactivity of the reactive functional groups (a1) of A) is a uniform type of crosslinking agent, a plurality of types may be used in combination. From the viewpoint of easy control of the three-dimensional network structure formed of the second (meth) acrylate polymer (B), for example, only an isocyanate crosslinking agent is used, and as the functional group, one type is preferably used. The crosslinking agent, further, as a compound, it is particularly preferable to use only one crosslinking agent.

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

On the other hand, the crosslinking agent (C) is an epoxy crosslinking agent, and the aziridine is crosslinked. In the case of a crosslinking agent or a metal complex-based crosslinking agent, the reactive functional group (a1)-containing monomer of the polymer (A) preferably contains a hydroxyl group-containing monomer as a polymer (B)-containing reactivity. The functional group (b1) monomer, preferably a carboxyl group-containing monomer, is a reactive functional group (b2)-containing monomer of the polymer (B), preferably a hydroxyl group-containing monomer.

The flexibility of the bond formed between the crosslinking agent (C) and the polymer (B), and the stability of the crosslinking reaction, further, the reactive group of the polymer (A) is appropriately aligned with the decane coupling agent (E) The reaction has a beneficial viewpoint of improving the adhesion durability of the obtained adhesive, and the crosslinking agent (C) is an isocyanate crosslinking agent, and the reactive functional group (a1) monomer of the polymer (A) is The carboxyl group-containing monomer is such that the reactive functional group (b1)-containing monomer of the polymer (B) is a hydroxyl group-containing monomer, and it is particularly preferred that the reactive functional group-containing (b2) monomer is not used.

The antistatic agent (D) may be provided with an antistatic property to the obtained adhesive as long as it does not inhibit the effects of the present invention, and examples thereof include an ionic compound, a surfactant, and the like, and an ionic compound is preferred. . Ionic compounds, liquids, solids. Here, the ionic compound in the present specification is a compound in which a cation and an anion are mainly bonded together by electrostatic attraction.

As the ionic compound, a nitrogen sulfonium salt, a sulfur-containing sulfonium salt, a phosphorus-containing phosphonium salt, an alkali metal salt, and an alkaline earth metal salt are preferable. Further, as the alkali metal salt, a lithium salt and a potassium salt are preferred. Specific examples of the above-mentioned charge preventing agent (D) include N-butyl 4-methylpyridinium hexafluorophosphate, n-hexyl 4-methylpyridinium hexafluorophosphate, and n-butyl 2-hexylpyridinium. Perchlorate, double (fluorine Sulfonimide) potassium (KFSI), bis(trifluoromethanesulfonimide) potassium (KTFSI), bis(fluorosulfonimide)lithium (LiFSi), bis(trifluoromethaneimide)lithium ( LiTFSI), n-butyl 2-hexylpyridinium bis(trifluoromethanesulfonyl)imide, and the like. The above-mentioned charging inhibitor (D) may be used alone or in combination of two or more.

The content of the antistatic agent (D) in the adhesive composition of the present embodiment is preferably from 0.1 to 30% by mass, particularly preferably from 0.5 to 20% by mass, more preferably from 1.0 to 10.0% by mass. . When the content of the charge prevention agent (D) is within the above range, the charge prevention property can be effectively exhibited, and the other components (A) to (C) in the adhesive composition of the present embodiment can be secured. Containing amount.

Further, the charge preventing agent (D) is preferably used alone, but it is preferably used in combination with a dispersing agent. When the solubility of the charge preventing agent (D) in the adhesive composition is insufficient, the solubility can be improved by the use of the dispersing agent in combination.

As the dispersing agent, for example, an alkyl glycol dialkyl ether or the like is preferred. Specific examples of the alkyl glycol dialkyl ether include octanediol dibutyl ether, octanediol diethyl ether, octanediol dimethyl ether, and hexanediol dibutyl ether. Alcohol diethyl ether, hexanediol dimethyl ether, tetraethylene glycol dibutyl ether, tetraethylene glycol diethyl ether, tetraethylene glycol dimethyl ether (hereinafter, also referred to as "four symmetrical diether" "), triethylene glycol diethyl ether, triethylene glycol dimethyl ether and the like. These dispersing agents may be used alone or in combination of two or more.

The blending amount of the dispersing agent is preferably 0.5 to 1.5 in terms of the molar ratio of the antistatic agent (D), more preferably 0.7 to 1.2, and particularly preferably 0.9 to 1.1.

Further, as described above, the first (meth) acrylate polymer (A) or the first (meth) acrylate polymer (A) and the second (meth) acrylate polymer (B) are constituted as When the component contains an alkyleneoxy group, the content of the charge preventing agent (D) can be reduced. Specifically, the content of the adhesive composition in the present embodiment is preferably from 0.1 to 10.0% by mass, particularly preferably from 0.5 to 5.0% by mass, and more preferably from 1.0 to 3.0% by mass.

The adhesive composition of the present embodiment preferably further contains a decane coupling agent (E). When the decane coupling agent (E) is contained and the first (meth) acrylate polymer (A) has a carboxyl group, the organic reactive group of the decane coupling agent (E) and the like (1) (meth) acrylate are polymerized. The carboxyl group of the substance (A) is reacted, and on the other hand, the alkoxy group of the decane coupling agent (E) acts on the adhering surface of the glass substrate or the like. Therefore, for example, when the polarizing plate is bonded to a liquid crystal glass unit or the like, the adhesion between the adhesive and the liquid crystal glass unit is further improved. Further, when the reactive functional group (a1) of the polymer (A) is other than a carboxyl group, the decane coupling agent (E) having an organic reactive group which acts on the reactive functional group (a1) is preferably used.

The decane coupling agent (E) is an organic ruthenium compound having at least one alkoxy fluorenyl group in the molecule, and has good compatibility with an adhesive component and has a light-transmitting property, and is preferably substantially transparent. . The amount of the decane coupling agent (E) to be added is preferably 0.01 to 1.0 part by mass, more preferably 0.05 to 0.5 part by mass, per 100 parts by mass of the first (meth) acrylate polymer (A). .

Specific examples of the decane coupling agent (E) include a polymerizable unsaturated group such as vinyl trimethoxy decane, vinyl triethoxy decane or methacryloxypropyl trimethoxy decane. An anthracene compound; an antimony compound having an epoxy structure such as 3-glycidyl ether propyl trimethoxy decane or 2-(3,4-epoxycyclohexyl)ethyltrimethoxy decane; 3-aminopropyltrimethyl Aminoguanidine compound such as oxoxane, n-(2-aminoethyl)-3-aminopropyltrimethoxydecane, n-(2-aminoethyl)-3-aminopropylmethyldimethoxydecane 3-chloropropyltrimethoxydecane; 3-isocyanatepropyltriethoxydecane, and 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 acrylic adhesive, for example, an adhesion-imparting agent, an oxidation preventive agent, an ultraviolet absorber, a light stabilizer, a softener, a filler, and a refractive index adjuster may be added, if necessary. .

[Method for Producing Adhesive Composition]

In the above adhesive composition, the first (meth) acrylate polymer (A) and the second (meth) acrylate polymer (B) are separately produced, and they may be mixed at the same time. In the stage, a crosslinking agent (C), a charge prevention agent (D), and a decane coupling agent (E) are added as needed.

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

The polymerization initiator may, for example, be an azo compound or an organic peroxide, and two or more types may be used in combination. As the azo compound, 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutylcyano), 1,1'-azobis(cyclohexane) can be exemplified. 1-nitrile), 2,2'-azobis(2,4-dimethylcarbonitrile), 2,2'-azobis(2,4-dimethyl-4-methoxy nitrile), dimethyl 2,2'-azobis(2-methylpropionate), 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis (2) -hydroxymethylpropionitrile) and 2,2'-azobis[2-(2-imidazolin-2-yl)propane].

As the organic peroxide, for example, benzoyl peroxide, t-butyl peroxybenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate Ester, di(2-ethoxyethyl) peroxydicarbonate, t-butyl peroxy neopentate, t-butyl peroxypivalate, (3,5) , 5-trimethylhexanoyl) peroxide, dipropionyl peroxide, diacetyl peroxide, and the like.

Further, in the above polymerization process, the weight average molecular weight of the obtained polymer can be adjusted by blending a chain shifting agent such as 2-mercaptoethanol.

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

Dilute the adhesive composition into a dilution solvent of the coating solution, Examples thereof include aliphatic hydrocarbons such as hexane, heptane, and cyclohexane; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as dichloromethane and dichloroethane; methanol, ethanol, propanol, and butanol. And an alcohol such as 1-methoxy-2-propanol; a ketone such as acetone, methyl ethyl ketone, 2-pentanone, isophorone or cyclohexanone; an ester of ethyl acetate or butyl acetate; A cellosolve solvent such as ethyl cellosolve.

As described above, the concentration ‧ viscosity of the prepared coating solution is not particularly limited as long as it is within the range of application, 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 it is worthwhile to apply the solution, the addition of a diluent solvent or the like is not a requirement, as long as the adhesive composition has a viscosity to be applied, and the like, and a diluent solvent may not be added. In this case, the adhesive composition can be used as a coating solution as it is.

[adhesive]

The adhesive of the present embodiment is obtained by crosslinking the above-mentioned adhesive composition. The crosslinking of the above adhesive composition can be carried out by heat treatment. Further, this heat treatment can also serve as a drying treatment for volatilizing the diluted solvent or the like of the adhesive composition.

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

Through the above heat treatment (and aging), the second (meth) acrylate polymer (B) is crosslinked by the crosslinking agent (C), and the three-dimensional network is simultaneously The first (meth) acrylate polymer (A) was inserted into the structure to form the above structure X (presumed). When the first (meth) acrylate polymer (A) has a carboxyl group, the first (meth) acrylate polymer (A) reacts with the decane coupling agent (E) to form a liquid crystal cell or the like of the adhesive. The bonding durability of the glass substrate is improved.

The surface resistivity of the adhesive of the present embodiment is preferably 3.0 × 10 ¹¹ Ω/sq or less, more preferably 1.0 × 10 ¹¹ Ω/sq or less, further preferably 8.0 × 10 ¹⁰ Ω/sq or less. When the surface resistance is equal to or less than the above value, the charge prevention property can be sufficiently exerted. In addition, in the present embodiment, the content of the charge preventing agent (D) in the adhesive composition can be sufficiently exhibited as described above, even if it is 3% by mass or less.

The adhesive force of the adhesive of the present embodiment is preferably 0.1 to 50 N/25 mm for the adhesion to the alkali-free glass, particularly preferably 0.5 to 30 N/25 mm, more preferably 3.0 to 20 N/25 mm. Further, the above-mentioned adhesive force is a 180° stretch peeling adhesive force (peeling speed 300 mm/miN) in accordance with JIS Z0237. The adhesive was applied to the adhesive, and after pressurizing at 0.5 MPa and 50 ° C for 20 minutes, the measurement was carried out by placing it at 23 ° C and 50% RH for 24 hours. When the adhesive force is within the above range, when applied to an optical member such as a polarizing plate, lifting, peeling, and the like can be prevented.

Further, in the adhesive of the present embodiment, the gel fraction is preferably from 30 to 90%, particularly preferably from 40 to 80%, more preferably from 45 to 75%. The gel fraction of the adhesive of the present embodiment, that is, the degree of crosslinking is within the above range, and the three-dimensional network structure formed by crosslinking of the second (meth) acrylate polymer (B) can be satisfactorily Forming, the adhesive is resistant to light leakage and durability Both sides are fine.

Further, the gel fraction of the adhesive is a value at the time of attachment (during the ripening period), specifically, the adhesive composition is applied onto the release sheet, and after heat treatment, at 23 ° C, 50% RH. The gel fraction after storage on the 7th day in the environment. This is due to the gel fraction of the adhesive, which varies before passing through the ripening period. From such a point of view, if the passage of the ripening period is unknown, it can be stored again in the environment of 23 ° C and 50% RH for 7 days. If the gel fraction is within the above range, there is no problem. .

The adhesive described above is preferably applied to an optical member such as an optical member such as a polarizing film (polarizing film) and a phase difference plate (phase difference film), or a polarizing plate (polarizing film) and The phase difference plate (phase difference film) is well bonded to the glass substrate. Since the adhesive of the present embodiment has charge prevention property, static electricity is hard to occur, and the problem of static electricity can be effectively suppressed. Further, since the adhesive layer formed of the above-mentioned adhesive has a very excellent stress relaxation rate, even when the dimensional change of the adherend is large, the stress generated by the dimensional change can be absorbed and moderated by the adhesive layer. Therefore, the light leakage for the optical member as described above can be effectively prevented without being peeled off from the adherend for a long period of time. In other words, the adhesive of the present embodiment has both charge prevention properties and light leakage resistance and durability.

[adhesive sheet]

As shown in Fig. 1, the adhesive sheet 1A of the first embodiment is a release sheet 12 in this order from the bottom, and an adhesive layer in which the release faces of the release sheets 12 are stacked. 11. The substrate 13 is laminated on the adhesive layer 11.

Further, as shown in Fig. 2, the adhesive sheet 1B of the second embodiment includes two release sheets 12a and 12b and a binder layer 11 held by the two release sheets 12a and 12b, whereby the above-mentioned adhesive layer 11 and The peeling faces of the two peeling sheets 12a and 12b are in contact with each other. In addition, the peeling surface of the peeling sheet in this specification is a surface which has the peeling property in the peeling sheet, and the surface which carried out the peeling process, and the surface which showed the peeling-

In any 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 selected 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, as an optical member, particularly as a polarizing plate. When the adhesive layer is used, it is preferably 10 to 50 μm, particularly preferably 10 to 30 μm.

The substrate 13 is not particularly limited, and can be used as a material generally used for a substrate sheet of an adhesive sheet. For example, a woven fabric or a nonwoven fabric of rayon, acrylic, polyester, or the like may be used in addition to the optical member; paper of the upper quality paper, cellophane, impregnated paper, copper paper, etc.; aluminum, copper, etc. Metal foil; polyurethane foam, foam of polyethylene foam, etc.; polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc. Ester film, polyurethane film, polyethylene film, polypropylene film, cellulose film of triacetyl cellulose, polydichloroethane film, polyvinylidene chloride film, polyvinyl alcohol film, B A vinyl film of a vinyl acetate copolymer film, a polystyrene film, a polycarbonate film, an acrylic resin film, a borneol resin film, or a cycloolefin resin film; or a mixture of two or more of these may be used. . For plastic film, one-axis calendering or biaxial calendering can be used.

Examples of the optical member include a polarizing plate (polarizing 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, a diffusion film, and a half. Through a reflective film or the like. Among them, the polarizing plate (polarizing film) is suitable for shrinkage and has a large dimensional change, and is suitable for forming an adhesive (the above-mentioned adhesive layer 11) of the present embodiment from the viewpoint of light leakage resistance.

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

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 polydichloroethane-based film, and dichloroethane. Base copolymer film, polyethylene terephthalate film, polyethylene naphthalate film, polybutylene terephthalate film, polyurethane film, vinyl acetate film, ion exchange resin film , ethylene ‧ (meth) acrylate copolymer film, ethylene ‧ (meth) acrylate copolymer film, polystyrene film, polycarbonate film, polyamide film, fluororesin film, and the like. Further, these crosslinked films are also applicable. Further, these laminated films can also be used.

The release surface of the release sheet (particularly the surface in contact with the adhesive layer 11) is preferably subjected to a release treatment. The release agent used in the release treatment may, for example, be an alkyd, a siloxane, a fluoro, an unsaturated polyester or a polyene. A stripping agent for hydrocarbons and waxes.

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

The pressure-sensitive adhesive sheet 1A is produced by applying a solution (coating solution) containing the above-mentioned adhesive composition to a release surface of the release sheet 12, and heat-treating the adhesive layer 11 to form an adhesive layer 11. The substrate 13 is stacked. After that, it is preferable to set the ripening period.

In addition, the conditions regarding the heat treatment and the ripening are as described above.

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

The method of applying the coating solution described above may, for example, be a stick coating method, a doctor blade method, a roll coating method, a blade coating method, a die coating method, a gravure coating method, or the like.

Here, for example, when a liquid crystal display device including a liquid crystal cell and a polarizing plate is manufactured, a polarizing plate is used as the base material 13 of the adhesive sheet 1A, and the peeling sheet 12 of the above-mentioned adhesive sheet 1A is exposed to an adhesive layer. 11 and the liquid crystal unit can be attached.

Further, for example, when a liquid crystal display device in which a retardation plate is disposed between a liquid crystal cell and a polarizer, for example, first, the release sheet 12a (or 12b) of one of the adhesive sheets 1B is peeled off, and the adhesive sheet 1B is exposed. The adhesive layer 11 is bonded to the phase difference plate. Then, the release sheet 12 of the adhesive sheet 1A using the polarizing plate as the substrate 13 is peeled off, and the adhesive sheet 1A is adhered. The exposed adhesive layer 11 is bonded to the above-described phase difference plate. Further, the other release sheet 12b (or 12a) is peeled off from the adhesive layer 11 of the adhesive sheet B, and the exposed adhesive layer 11 of the adhesive sheet B is bonded to the liquid crystal cell.

In the above-mentioned adhesive sheets 1A and 1B, since the adhesive layer 11 has charge prevention property, static electricity is less likely to occur, and it is possible to effectively suppress defects caused by static electricity. Further, since the stress relaxation rate of the adhesive layer 11 is extremely excellent, even when adhesion using, for example, a polarizing plate is used, the stress generated by the deformation of the polarizing plate can be absorbed by the adhesive layer 11 and moderated. Therefore, excellent light leakage resistance and high durability (presumed) can be exhibited.

The embodiments described above are described in order to better understand the present invention, but they are not intended to limit the invention. Therefore, each element described in the above embodiments includes all design changes and equivalents within the scope of the technology of the present invention.

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

[Examples]

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

[Example 1] 1. Modulation of polymer (A)

With a blender, thermometer, reflux cooler, drip device, and In the reaction vessel of the nitrogen introduction tube, 75.0 parts by mass of n-butyl acrylate, 20.0 parts by mass of 2-methoxyethyl acrylate, 5.0 parts by mass of acrylic acid, 200 parts by mass of ethyl acetate, and 2,2'-azo were added. 0.08 parts by mass of diisobutyl cyanide, and the air in the above reaction vessel was replaced with nitrogen. The mixture was stirred under a nitrogen atmosphere, and the reaction solution was heated to 60 ° C for 16 hours, and then cooled to room temperature. Here, a part of the obtained solution was subjected to molecular weight measurement by the following method, and it was confirmed that the polymer (A) having a weight average molecular weight of 1.2 million was formed.

2. Modulation of polymer (B)

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 to a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen introduction tube. 0.16 parts by mass of 2,2'-azobisisobutyronitrile and 0.3 parts by mass of 2-mercaptoethanol, and the air in the reaction vessel was replaced with nitrogen. The mixture was stirred under the nitrogen atmosphere, and the reaction solution was heated to 70 ° C to raise the temperature. After 6 hours, the reaction was cooled to room temperature. Here, a part of the obtained solution was subjected to molecular weight measurement by the following method, and the formation of the polymer (B) having a weight average molecular weight of 60,000 was confirmed.

3. Modulation of adhesive composition

100 parts by mass (solid content converted value) of the polymer (A) obtained in the above item (1) and 15 parts by mass (solid content converted value) of the polymer (B) obtained in the above item (2) are mixed. As the crosslinking agent (C), trishydroxymethylpropane was added in an amount equivalent to 0.6 equivalents of the hydroxyl group of the polymer (B). 2.21 parts by mass of a toluene diisocyanate (TDI-based) adduct (manufactured by Nippon Polyurethane Co., Ltd., trade name "CORONET-L"). Finally, as the charge preventing agent (D), 2.0 parts by mass of n-butyl 4-methylpyridinium hexafluorophosphate, and as a decane coupling agent (E), 3-glycidyl ether propyl trimethoxy decane was added (Shin-Etsu 0.2 parts by mass of the product name "KBM403" manufactured by Chemical Industry Co., Ltd., and sufficiently stirred to obtain a diluted solution of the adhesive composition.

Here, the formulation of the above adhesive composition is shown in Table 1. In addition, the details and the like described in Table 1 are as follows.

[Polymer (A) and (B)]

BA: n-butyl acrylate

AA: Acrylic

MA: methacrylic acid

MEA: 2-methoxyethyl acrylate

HEA: 2-hydroxyethyl acrylate

4HBA: 4-hydroxybutyl acrylate

PhEA: phenoxyethyl acrylate

[Isocyanate crosslinking agent (C)]

CORONET-L: toluene diisocyanate adduct of trimethylolpropane (manufactured by Nippon Polyurethane Co., Ltd., trade name "CORONET-L")

CORONET-HX: hexamethylene diisocyanate isocyanurate (manufactured by Nippon Polyurethane Co., Ltd., trade name "CORONET-HX")

DURANATE 24A-100: hexamethylene diisocyanate biuret (manufactured by Asahi Kasei Chemicals Co., Ltd., trade name "DURANATE 24A-100")

[charge inhibitor (D)]

Pyridinium: n-butyl 4-methylpyridinium hexafluorophosphate

KFSI: bis(fluorosulfonimide) potassium (KFSI): mixed solution of four symmetrical diether = 1:1 (mass ratio) ※ The amount in the table is only KFSI

LiTFSI: bis(trifluoromethanephthalimide) lithium (LiTFSI): mixed solution of four symmetric diether = 1:1 (mass ratio) ※ The compounding amount in the table is only the value of LiTFSI

AS-804: The first industrial pharmaceutical company, antimony salt antistatic agent, trade name "AS-804"

[decane coupling agent (E)]

KBM403: 3-glycidyl ether propyl trimethoxy decane (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")

X-41-1059A: Olefin-type decane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "X-41-1059A")

A release sheet of a release sheet (SP-PET3811, thickness: 38 μm, manufactured by Linde Co., Ltd.) which was subjected to a release treatment on one side of a polyethylene terephthalate film with a decane-based release agent. The diluted solution of the obtained adhesive composition was applied by a doctor blade method to have a thickness of 25 μm after drying, and then heat-treated at 90 ° C for 1 minute to form an adhesive layer.

Then, polarized light composed of a polarizing film with a discotic liquid crystal layer The polarizing film in which the film and the viewing angle expansion film are integrated is bonded, and the adhesive layer and the disk-shaped liquid crystal layer are brought into contact with each other, and aged at 23 ° C and 50% RH for 7 days to obtain a polarizing plate with an adhesive layer.

[Examples 2-26, Comparative Example 1-3]

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

Here, the weight average molecular weight (Mw) 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 column (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

[Experimental Example 1] (Measurement of gel fraction)

In the examples or comparative examples, the polarizing plate used in the production of the polarizing plate with the adhesive layer was replaced, and one side of the polyethylene terephthalate film was treated with a decane-based release agent. Stripping treatment An adhesive sheet (SP-PET3801, thickness: 38 μm) was produced from the sheet (manufactured by Linde Co., Ltd.) to prepare an adhesive sheet. Specifically, the release sheets were laminated on the exposed adhesive layer of the structure composed of the release sheet/adhesive layer (thickness: 25 μm) obtained in the production process of the example or the comparative example to bond The layer is in contact with the side of the release treatment surface. Thus, an adhesive sheet having a structure of a release sheet/adhesive layer/release sheet was obtained.

The obtained adhesive sheet was aged at 23 ° C and 50% RH for 7 days. Thereafter, the above-mentioned adhesive sheet was made into a sample having a size of 80 mm × 80 mm, and the adhesive layer was wrapped with a polyester mesh (mesh size 200), and only the mass of the adhesive was weighed with a precision balance. This mass is taken as M1.

For the bonding, the adhesive wrapped with the above polyester mesh was immersed in ethyl acetate at room temperature (23 ° C) for 24 hours. Thereafter, 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 further dried in an oven at 80 ° C for 12 hours. Only the quality of the dried adhesive is weighed with a precision balance. The mass at this time is taken as M2. The gel fraction (%) is represented by (M2/M1) × 100. The results are shown in Table 2.

[Experimental Example 2] (Light leakage test)

The polarizing plate with an adhesive layer obtained in the example or the comparative example was adjusted to a size of 233 mm × 309 mm by a cutting device (Super Knife, manufactured by Takino Seisakusho Co., Ltd., PN1-600). The peeling sheet was peeled off, and the exposed adhesive layer was attached to an alkali-free glass (manufactured by Corning Co., Ltd., Eagle XG), and then pressurized in a kettle made by Kurihara Seisakusho Co., Ltd. at 0.5 MPa and 50 ° C for 20 minutes. Further, in the above-described bonding, the polarizing plate with the adhesive layer is in a Nicols cross state with a polarization axis (polarizing axis: ∠45°, ∠135°). In this state, After allowing to stand for 250 hours in a dry environment of 80 ° C, the film was allowed to stand for 2 hours in an environment of 23 ° C and 50% RH, and the light leakage property was evaluated by the method shown below. The results are shown in Table 2.

<Light leakage evaluation: △L*>

The brightness L* of each field shown in FIG. 3 in the above sample was measured using MCPD-2000 manufactured by Otsuka Electronics Co., Ltd., and the luminance difference ΔL* was obtained by the following equation as light leakage: ΔL*=[( b+c+d+e)/4]-a (a, b, c, d and e, respectively, in the A field, B field, C field, D field and E field, pre-specified measurement points (in each field) The brightness of the central portion 1) is taken as light leakage. The smaller the value of ΔL*, the smaller the light leakage.

[Experimental Example 3] (Durability Evaluation)

The polarizing plate having the adhesive layer obtained in the examples or the comparative examples 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 attached to an alkali-free glass (Eagle XG, manufactured by Corning Co., Ltd.), and pressurized in a kettle made by Kurihara Co., Ltd. at 0.5 MPa at 50 ° C for 20 minutes.

Thereafter, the environment was subjected to the following durability conditions, and after 500 hours, observation was performed with a magnifying glass of 10 times. The change in appearance is based on the following. The results are shown in Table 2.

◎: There are no problems in the 4 sides.

○: There were no problems in the four sides from 0.6 mm or more from the outer peripheral end.

×: at least one side of four sides, and a portion of 0.6 mm or more from the outer peripheral end portion, Abnormal appearance of an adhesive of 0.1 mm or more with float, peeling, foaming, streaking, etc.

<endurance condition>

‧80 ° C drying

‧60 ° C, relative humidity 90% RH

[Experimental Example 4] (Measurement of adhesion)

The polarizing plate with the adhesive layer obtained in the examples or the comparative examples was cut to prepare a sample having a width of 25 mm and a length of 100 mm. The peeling sheet was peeled off from the sample, and the exposed adhesive layer was attached to the sample on an alkali-free glass (Eagle XG, manufactured by Corning Co., Ltd.), and thereafter, it was 0.5 MPa in an autoclave manufactured by Kurihara Seisakusho Co., Ltd. Pressurize at 50 ° C for 20 minutes. Thereafter, it was allowed to stand at 23 ° C, 50% RH for 24 hours, and then subjected to a tensile tester (TENSILON, manufactured by Orui Co., Ltd.) at a peeling speed of 300 mm/min and a peeling angle of 180°. The adhesion after 1 day was attached; N/25 mm) was measured. The results are shown in Table 2.

[Experimental Example 5] (Measurement of surface resistance value)

The polarizing plate with an adhesive layer obtained in the examples or the comparative examples was cut into a size of 50 mm × 50 mm, and the obtained sample was allowed to stand at a temperature of 23 ° C and a humidity of 50% RH for 24 hours. Thereafter, the release sheet was peeled off, and the surface of the exposed adhesive layer was measured with a resistivity meter (manufactured by Mitsubishi Chemical Analysis Co., Ltd., high resistance meter UP MCP-HT450 type), and the surface resistance value (Ω/sq) was measured in accordance with JIS K6911. The results are shown in Table 2.

As is clear from Table 2, the polarizing plate with an adhesive layer obtained in the examples has excellent adhesion and charge prevention, and exhibits excellent stress relaxation rate, light leakage resistance, and durability. Sex is very good.

[Industrial use possibilities]

The adhesive composition and the adhesive of the present invention can be suitably used when used in an optical member, for example, when a polarizing plate and a phase difference plate are bonded, and the adhesive sheet of the present invention is used as a polarizing plate and a phase difference. An adhesive sheet for an optical member such as a plate can be suitably used.

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

1A‧‧‧Adhesive tablets

11‧‧‧Adhesive layer

12‧‧‧ peeling layer

13‧‧‧Substrate

Claims (14)

An adhesive composition 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 crosslinking agent (C), and a charge prevention agent (D), wherein the second (meth) acrylate is 100 parts by mass of the first (meth) acrylate polymer (A). The ratio of the polymer (B) is 5 to 50 parts by mass, and the second (meth) acrylate polymer (B) contains, as a constituent component, a single functional group (b1) having a reaction with the crosslinking agent (C). Further, the ratio of the monomer having the functional group (b1) is 5% by mass or more and 50% by mass or less of the second (meth) acrylate polymer (B), and the first (methyl group) The acrylate polymer (A) does not contain a monomer having a functional group reactive with the crosslinking agent (C) as a constituent component, or contains a reactivity with the crosslinking agent (C) as a constituent component. The monomer of the functional group (a1) in which the above functional group (b1) of the (meth) acrylate polymer (B) is further low. The adhesive composition according to claim 1, wherein the first (meth) acrylate polymer (A) or the first (meth) acrylate polymer (A) and the above The 2 (meth) acrylate polymer (B) contains 5 to 50% by mass of an alkylene group-containing monomer as a constituent monomer unit of these polymers. The adhesive composition according to claim 1, wherein the charge preventing agent (D) is an ionic compound. The adhesive composition according to claim 3, wherein the ionic compound is composed of a nitrogen-containing phosphonium salt, a sulfur-containing phosphonium salt, a phosphorus-containing phosphonium salt, an alkali metal salt, and an alkaline earth metal salt. At least one selected in the group. The adhesive composition according to claim 4, wherein the alkali metal salt is at least one selected from the group consisting of a lithium salt and a potassium salt. The adhesive composition according to the first aspect of the invention, wherein the functional group (a1) in the first (meth) acrylate polymer (A) is a carboxyl group, and the second (meth) acrylate is polymerized. The functional group (b1) of the substance (B) is a hydroxyl group, and the crosslinking agent (C) is an isocyanate type crosslinking agent. The adhesive composition according to claim 1, wherein the first (meth) acrylate polymer (A) does not contain a carboxyl group-containing monomer as a monomer unit constituting the polymer, or The functional group (a1) contains a carboxyl group-containing monomer in an amount of 15% by mass or less. The adhesive composition according to claim 1, wherein the second (meth) acrylate polymer (B) contains 5 to 40% by mass of a hydroxyl group-containing monomer as the functional group (b1). . The adhesive composition according to claim 6, wherein the content of the isocyanate crosslinking agent is the functional group (b1) in the second (meth) acrylate polymer (B). The amount of the isocyanate group of the isocyanate crosslinking agent is 0.1 to 3.5 equivalents. An adhesive which is obtained by crosslinking an adhesive composition according to any one of claims 1 to 9. The adhesive according to claim 10, wherein the surface resistivity of the adhesive is 3.0 × 10 ¹¹ Ω/sq or less. 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 according to claim 12, wherein the substrate is an optical member. An adhesive sheet comprising two release sheets and an adhesive layer held by the release sheet, wherein the adhesive layer is in contact with the release faces of the two release sheets, wherein the adhesive layer is patented The adhesive composition according to item 10.