JP7070981B2 - Adhesive composition for polarizing plate and polarizing plate with adhesive layer - Google Patents

Description

The present invention relates to a pressure-sensitive adhesive composition for a polarizing plate and a polarizing plate with a pressure-sensitive adhesive layer.

Many mobile electronic devices such as mobile phones and mobile terminals have a built-in liquid crystal display device. Generally, a liquid crystal display device includes a liquid crystal cell in which a liquid crystal layer is sandwiched between two glass substrates, and a polarizing plate arranged on both sides of the liquid crystal cell. The liquid crystal cell and the polarizing plate are generally bonded to each other via a pressure-sensitive adhesive layer formed of an acrylic pressure-sensitive adhesive from the viewpoint of ensuring the visibility of the liquid crystal display device.

The polarizing plate is usually composed of laminated members having different shrinkage rates. Therefore, the polarizing plate may be warped due to changes in temperature, humidity, and the like, and bubbles, floating, and peeling may occur at the interface between the polarizing plate and the pressure-sensitive adhesive layer. Therefore, the adhesive used for bonding the liquid crystal cell and the polarizing plate has a property (so-called durability) that can suppress the occurrence of bubbles, floating, and peeling even when exposed to a harsh environment. It is required to be able to form a pressure-sensitive adhesive layer.

In response to such a requirement, for example, Patent Document 1 describes a pressure-sensitive adhesive layer in which defects such as foaming, floating, peeling, and streaks are unlikely to occur even when exposed to a high temperature and high humidity environment of 60 ° C. and 90% RH. As a pressure-sensitive adhesive composition capable of forming the above, a first (meth) acrylic acid ester polymer (A) having a weight average molecular weight of 500,000 to 3,000,000 and a second (meth) having a weight average molecular weight of 8,000 to 300,000. A tacky composition containing an acrylic acid ester polymer (B) and a cross-linking agent (C), wherein the first (meth) acrylic acid ester polymer (A) substantially contains an acidic group. The second (meth) acrylic acid ester weight contains a hydroxyl group-containing monomer (a) whose reactivity with the cross-linking agent (C) satisfies the formula (I) as a monomer unit constituting the polymer. The coalescence (B) contains a hydroxyl group-containing monomer (b) having a reactivity with the cross-linking agent (C) satisfying the formula (I) as a monomer unit constituting the polymer and which does not substantially contain an acidic group. A tacky composition characterized by containing [reactivity with a cross-linking agent (C): hydroxyl group-containing monomer (a) <hydroxyl-containing monomer (b) ... (I)] is disclosed.

Japanese Unexamined Patent Publication No. 2013-10838

The pressure-sensitive adhesive composition used for the polarizing plate (so-called pressure-sensitive adhesive composition for polarizing plates) suppresses the occurrence of bubbles, floating, and peeling even when exposed to a high temperature (for example, 85 ° C. or higher) environment. It is required to be able to form a pressure-sensitive adhesive layer having excellent properties, so-called high-temperature durability. Further, in addition to high temperature durability, the pressure-sensitive adhesive composition for a polarizing plate has a property that it is difficult to cause warpage of glass when it is attached to glass (hereinafter, also referred to as “glass warpage inhibitory property”), and polarization. It is desirable to be able to form an adhesive layer having excellent properties (hereinafter, also referred to as “workability”) in which adhesive residue is unlikely to occur on the cutting blade when the plate is cut.

Generally, in order to improve the high temperature durability of the pressure-sensitive adhesive layer, for example, it is conceivable to increase the cohesive force of the pressure-sensitive adhesive layer. However, if the cohesive force of the pressure-sensitive adhesive layer is increased, the high-temperature durability of the pressure-sensitive adhesive layer is improved, but the glass tends to warp when attached to the glass. On the other hand, if the cohesive force of the adhesive is reduced by lowering the gel fraction after cross-linking in order to improve the warpage suppressing property of the glass, adhesive residue on the cutting blade is likely to occur when the polarizing plate is cut. Tend.
As described above, it has been difficult to improve high temperature durability, processability, and glass warpage suppressing property in the pressure-sensitive adhesive composition for polarizing plates.

Regarding the above points, the adhesive composition described in Patent Document 1 is said to have excellent durability when exposed to a high temperature and high humidity environment of 60 ° C. and 90% RH. No attention has been paid to forming an adhesive layer that satisfies all of high temperature durability, processability, and glass warpage suppression property.

The problem to be solved by the present invention is the pressure-sensitive adhesive composition for a polarizing plate capable of forming a pressure-sensitive adhesive layer having excellent high-temperature durability, processability, and glass warpage suppressing property, and the pressure-sensitive adhesive composition for a polarizing plate. It is to provide a polarizing plate with a pressure-sensitive adhesive layer provided with the formed pressure-sensitive adhesive layer.

Specific means for solving the problem include the following aspects.
<1> Containing a structural unit derived from a monomer having a hydroxyl group and a structural unit derived from a (meth) acrylic acid alkyl ester monomer in an amount of 50% by mass or more based on all the structural units, and by weight average. With the (meth) acrylic copolymer (A) having a molecular weight in the range of 800,000 or more and less than 1.4 million,
It contains a structural unit derived from a monomer having a hydroxyl group and a structural unit derived from a (meth) acrylic acid alkyl ester monomer in an amount of 50% by mass or more based on all the structural units, and has a weight average molecular weight of 140. With the (meth) acrylic copolymer (B) in the range of 10,000 or more and 2 million or less,
It contains a structural unit derived from a monomer having a hydroxyl group and a structural unit derived from a (meth) acrylic acid alkyl ester monomer in an amount of 50% by mass or more based on all the structural units, and has a weight average molecular weight of 0. . With the (meth) acrylic copolymer (C) in the range of 20,000 or more and 50,000 or less,
Contains an isocyanate-based cross-linking agent,
A single having the hydroxyl group in the (meth) acrylic copolymer (A) with respect to the content of the structural unit derived from the monomer having the hydroxyl group in the (meth) acrylic copolymer (B). Percentage of Constituent Units Derived from Quantities [Contents of Constituent Units Derived from Monomers with Hydroxylates in (Meta) Acrylic Copolymers / (Meta) Acrylic Copolymers ((meth) Acrylic Copolymers B) Content of structural units derived from the monomer having a hydroxyl group in B)] is 1/1 to 1/200 on a mass basis.
A single having the hydroxyl group in the (meth) acrylic copolymer (A) with respect to the content of the structural unit derived from the monomer having the hydroxyl group in the (meth) acrylic copolymer (C). Percentage of Constituent Units Derived from Quantities [Contents of Constituent Units Derived from Monomers with Hydroxylates in (Meta) Acrylic Copolymers / (Meta) Acrylic Copolymers ((meth) Acrylic Copolymers C) Content of structural unit derived from a monomer having a hydroxyl group in C)] is 1/1 to 1/1000 on a mass basis, a pressure-sensitive adhesive composition for a polarizing plate.

<2> The polarization according to <1>, wherein the glass transition temperature of the (meth) acrylic copolymer (A) and the (meth) acrylic copolymer (B) are both −25 ° C. or lower. Adhesive composition for boards.
<3> The pressure-sensitive adhesive composition for a polarizing plate according to <1> or <2>, wherein the (meth) acrylic copolymer (C) has a glass transition temperature of 70 ° C. or higher.
<4> The content of the isocyanate-based cross-linking agent is the above-mentioned (meth) acrylic-based copolymer (A), the above-mentioned (meth) acrylic-based copolymer (B), and the above-mentioned (meth) acrylic-based copolymer ( The pressure-sensitive acrylic composition according to any one of <1> to <3>, which is 1.3 parts by mass to 8.0 parts by mass with respect to 100 parts by mass of the total content of C).
<5> The hydroxyl group in the (meth) acrylic copolymer (A) with respect to the content of the structural unit derived from the monomer having the hydroxyl group in the (meth) acrylic copolymer (B). Ratio of the content of the structural unit derived from the monomer having a hydroxyl group [Content of the structural unit derived from the monomer having a hydroxyl group in the (meth) acrylic copolymer (A) / (meth) acrylic-based copolymer The content of the structural unit derived from the monomer having a hydroxyl group in the polymer (B)] is 1/5 to 1/200 on a mass basis.
A single having the hydroxyl group in the (meth) acrylic copolymer (A) with respect to the content of the structural unit derived from the monomer having the hydroxyl group in the (meth) acrylic copolymer (C). Percentage of Constituent Units Derived from Quantities [Contents of Constituent Units Derived from Monomers with Hydroxylates in (Meta) Acrylic Copolymers / (Meta) Acrylic Copolymers ((meth) Acrylic Copolymers B) The content of the structural unit derived from the monomer having a hydroxyl group in B)] is 1/10 to 1/700 on a mass basis, according to any one of <1> to <4>. Adhesive composition for polarizing plate.
<6> At least one of the (meth) acrylic copolymer (A) and the (meth) acrylic copolymer (B) contains a structural unit derived from a monomer having an aromatic ring, <1. > The pressure-sensitive adhesive composition for a polarizing plate according to any one of <5>.
<7> A polarizing plate and a pressure-sensitive adhesive layer provided on the above-mentioned polarizing plate and formed by the pressure-sensitive adhesive composition for a polarizing plate according to any one of <1> to <6> are provided. Polarizing plate with adhesive layer.

According to the present invention, a pressure-sensitive adhesive composition for a polarizing plate capable of forming a pressure-sensitive adhesive layer having excellent high-temperature durability, processability, and glass warpage suppressing property, and a pressure-sensitive adhesive formed from the above-mentioned pressure-sensitive adhesive composition for a polarizing plate. A polarizing plate with an adhesive layer having a layer is provided.

Hereinafter, specific embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and can be carried out with appropriate modifications within the scope of the object of the present invention.

The numerical range indicated by using "-" in the present specification means a range including the numerical values before and after "-" as the minimum value and the maximum value, respectively.
In the numerical range described stepwise in the present specification, the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value of another numerical range described stepwise. .. Further, in the numerical range described in the present specification, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the value shown in the examples.
In the present specification, a combination of two or more preferred embodiments is a more preferred embodiment.
In the present specification, the amount of each component means the total amount of a plurality of kinds of substances when there are a plurality of kinds of substances corresponding to each component, unless otherwise specified.

As used herein, the term "adhesive composition" refers to a liquid or paste after the (meth) acrylic copolymer and the cross-linking agent (that is, the isocyanate compound) are mixed and before the cross-linking reaction is completed. Means a substance.
As used herein, the term "adhesive layer" means a film made of a substance after the cross-linking reaction in the pressure-sensitive adhesive composition is completed.
As used herein, the term "adhesion" means an object that comes into contact with the pressure-sensitive adhesive layer on the opposite side of the polarizing plate during use, and for example, a glass substrate of a liquid crystal cell can be an adherend.
In the present specification, the term "base material" refers to, for example, a polarizing plate, and the term "base material" is used in distinction from the term "adhesive body".

As used herein, the term "high temperature durability" refers to the property of being able to suppress the occurrence of air bubbles, floating, and peeling even when exposed to a high temperature (for example, 85 ° C. or higher) environment.
In the present specification, the generation of bubbles is referred to as "foaming".

As used herein, "(meth) acrylic" is a term that includes both "acrylic" and "methacrylic", and "(meth) acrylate" is a term that includes both "acrylate" and "methacrylate".

In the present specification, "n-" means normal, "i-" means iso, "s-" means secondary, and "t-" means tertiary.

[Adhesive composition for polarizing plate]
The pressure-sensitive adhesive composition for a polarizing plate of the present invention (hereinafter, also referred to as “pressure-sensitive adhesive composition”) is a structural unit derived from a monomer having a hydroxyl group, and 50% by mass or more with respect to all the structural units. A (meth) acrylic copolymer (A) containing a structural unit derived from a (meth) acrylic acid alkyl ester monomer and having a weight average molecular weight in the range of 800,000 or more and less than 1.4 million (hereinafter, "specified". (Meta) acrylic copolymer (A) ”), a structural unit derived from a monomer having a hydroxyl group, and a (meth) acrylic acid alkyl ester of 50% by mass or more with respect to all the structural units. A (meth) acrylic copolymer (B) containing a structural unit derived from a monomer and having a weight average molecular weight in the range of 1.4 million or more and 2 million or less (hereinafter, "specific (meth) acrylic copolymer weight". Combined (B) ”), a structural unit derived from a monomer having a hydroxyl group, and a composition derived from a (meth) acrylic acid alkyl ester monomer in an amount of 50% by mass or more based on all the structural units. A (meth) acrylic copolymer (C) containing a unit and having a weight average molecular weight in the range of 2,000 or more and 50,000 or less (hereinafter, “specific (meth) acrylic copolymer (C)””. Also referred to as) and an isocyanate-based cross-linking agent, with respect to the content of the structural unit derived from the monomer having a hydroxyl group in the (meth) acrylic-based copolymer (B), the (meth) acrylic-based Ratio of the content of the constituent unit derived from the monomer having a hydroxyl group in the copolymer (A) [The constituent unit derived from the monomer having a hydroxyl group in the (meth) acrylic copolymer (A) Content / content of structural units derived from the monomer having a hydroxyl group in the (meth) acrylic copolymer (B)] is 1/1 to 1/200 on a mass basis, and is (meth). The constituent unit derived from the monomer having a hydroxyl group in the (meth) acrylic copolymer (A) with respect to the content of the constituent unit derived from the monomer having a hydroxyl group in the acrylic copolymer (C). Content ratio of [(meth) acrylic copolymer (A) content of structural unit derived from monomer having hydroxyl group / (meth) acrylic copolymer (C) having hydroxyl group The content of the structural unit derived from the monomer] is 1/1 to 1/1000 on a mass basis.

The pressure-sensitive adhesive composition for a polarizing plate is attached to glass with a property of suppressing the occurrence of bubbles, floating, and peeling even when exposed to a high temperature (for example, 85 ° C. or higher) environment (that is, high temperature durability). A pressure-sensitive adhesive layer excellent in the property that the glass is less likely to warp (that is, the glass warp suppressing property) and the property that the cutting blade is less likely to have adhesive residue when the polarizing plate is cut (that is, workability). It is desirable to be able to form.
However, as described above, it has been difficult to improve high temperature durability, processability, and glass warpage suppressing property by simply adjusting the cohesive force of the pressure-sensitive adhesive layer.

On the other hand, in the pressure-sensitive adhesive composition of the present invention, three types of (meth) acrylic copolymers having different hydroxyl weights and molecular weights and isocyanate-based cross-linking agents are selected as the components of the pressure-sensitive adhesive composition. The degree of cross-linking was well controlled, and high temperature durability, workability, and warpage suppression property of glass were improved.
Specifically, the pressure-sensitive adhesive composition of the present invention has a configuration derived from a monomer having a hydroxyl group in the specific (meth) acrylic copolymer (A) having a weight average molecular weight in the range of 800,000 or more and less than 1.4 million. The content mass of the unit is relative to the content mass of the structural unit derived from the monomer having a hydroxyl group in the specific (meth) acrylic copolymer (B) having a weight average molecular weight in the range of 1.4 million or more and 2 million or less. A structural unit derived from a monomer having a hydroxyl group in a specific (meth) acrylic copolymer (C) having a weight average molecular weight of 2,000 or more and 50,000 or less, which is 1/1 to 1/200. Since it is 1/1 to 1/1000 of the content mass, the balance between the hardness and softness of the pressure-sensitive adhesive layer formed by controlling the cross-linking between each (meth) acrylic copolymer and the isocyanate-based cross-linking agent. As a result of being well adjusted, it is possible to realize the formation of a pressure-sensitive adhesive layer having excellent high-temperature durability, processability, and warpage suppressing property of glass.

Hereinafter, each component of the pressure-sensitive adhesive composition of the present invention will be described.
In addition, in this specification, a specific (meth) acrylic copolymer (A), a specific (meth) acrylic copolymer (B), and a specific (meth) acrylic copolymer (C) are generically referred to. , May be referred to as "specific (meth) acrylic copolymer".

[Specific (meth) acrylic copolymer (A)]
The (meth) acrylic copolymer (A) [that is, the specific (meth) acrylic copolymer (A)] contained in the pressure-sensitive adhesive composition of the present invention is a structural unit derived from a monomer having a hydroxyl group. , And 50% by mass or more of the structural units derived from the (meth) acrylic acid alkyl ester monomer with respect to all the structural units, and the weight average molecular weight is in the range of 800,000 or more and less than 1.4 million.

<Constituent unit derived from a monomer having a hydroxyl group>
The specific (meth) acrylic copolymer (A) contains a structural unit derived from a monomer having a hydroxyl group.
As used herein, the "constituent unit derived from a monomer having a hydroxyl group" means a structural unit formed by addition polymerization of a monomer having a hydroxyl group.

The type of the monomer having a hydroxyl group is not particularly limited.
Examples of the monomer having a hydroxyl group include a monomer having a hydroxyl group and an ethylenically unsaturated bond group.
Specific examples of the monomer having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 6-. Hydroxyhexyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, 3-methyl-3-hydroxybutyl (meth) acrylate, 1,1-dimethyl-3-hydroxybutyl (meth) ) Acrylate, 1,3-dimethyl-3-hydroxybutyl (meth) acrylate, 2,2,4-trimethyl-3-hydroxypentyl (meth) acrylate, 2-ethyl-3-hydroxyhexyl (meth) acrylate, N- Examples thereof include hydroxyethyl (meth) acrylamide.

As the monomer having a hydroxyl group, for example, hydroxyalkyl (meth) acrylate is preferable from the viewpoint of high temperature durability and good initial adhesive strength.
Further, as the hydroxyalkyl (meth) acrylate, for example, the compatibility and copolymerizability with the (meth) acrylic acid alkyl ester monomer described later are good, and the cross-linking reaction with the isocyanate-based cross-linking agent is good. From this point of view, a hydroxyalkyl (meth) acrylate having a hydroxyalkyl group having 1 to 5 carbon atoms is preferable, and a hydroxyalkyl (meth) acrylate having a hydroxyalkyl group having 2 to 4 carbon atoms is more preferable.

The specific (meth) acrylic copolymer (A) may contain only one type of structural unit derived from the monomer having a hydroxyl group, or may contain two or more types.

The content (ratio) of the structural unit derived from the monomer having a hydroxyl group in the specific (meth) acrylic copolymer (A) is the content (ratio) with respect to all the structural units of the specific (meth) acrylic copolymer (A). For example, the range of 0.01% by mass to 0.5% by mass is preferable, the range of 0.03% by mass to 0.2% by mass is preferable, and the range of 0.05% by mass to 0.1% by mass is preferable. preferable.
The content (ratio) of the structural units derived from the monomer having a hydroxyl group in the specific (meth) acrylic copolymer (A) is the same as that of all the structural units of the specific (meth) acrylic copolymer (A). When it is 0.01% by mass or more, the cross-linking reaction between the hydroxyl group and the isocyanate group of the isocyanate-based cross-linking agent proceeds more appropriately, and the cross-linking density of the formed pressure-sensitive adhesive layer becomes more appropriate, so that the pressure-sensitive adhesive The adhesion between the layer and the substrate becomes better. Therefore, the high temperature durability of the formed pressure-sensitive adhesive layer tends to be better.
The content (ratio) of the structural unit derived from the monomer having a hydroxyl group in the specific (meth) acrylic copolymer (A) is the same as that of all the structural units of the specific (meth) acrylic copolymer (A). When the content is 0.5% by mass or less, the hydroxyl group and the isocyanate group of the isocyanate-based cross-linking agent are not excessively cross-linked, so that a pressure-sensitive adhesive layer exhibiting appropriate flexibility is formed. The pressure-sensitive adhesive layer, which exhibits moderate flexibility, can sufficiently follow the expansion and contraction of the base material due to changes in temperature. Therefore, the high temperature durability of the formed pressure-sensitive adhesive layer tends to be better.

A single having a hydroxyl group in the specific (meth) acrylic copolymer (A) with respect to the content of the structural unit derived from the monomer having a hydroxyl group in the specific (meth) acrylic copolymer (B) described later. Percentage of Constituent Units Derived from Quantities [Contents of Constituent Units Derived from Monomers with Hydroxylates in the Specific (Meta) Acrylic Copolymer (A) / Specific (Meta) Acrylic Copolymers The content of the structural unit derived from the monomer having a hydroxyl group in the coalescence (B)] is 1/1 to 1/200, preferably 1/5 to 1/200 on a mass basis. It is more preferably 1/5 to 1/50, and even more preferably 1/5 to 1/10.
[Contents of structural units derived from the monomer having a hydroxyl group in the specific (meth) acrylic copolymer (A) / Monomer having a hydroxyl group in the specific (meth) acrylic copolymer (B) When the content of the structural unit derived from the above is 1/1 or more on a mass basis, the viscoelasticity of the pressure-sensitive adhesive layer at a high temperature (for example, 85 ° C. or higher) becomes low. Therefore, it is possible to realize an adhesive layer having excellent high temperature durability. In addition, the viscoelasticity of the pressure-sensitive adhesive layer at room temperature (for example, 23 ° C.) is increased. Therefore, a pressure-sensitive adhesive layer having excellent processability can be realized.
[Content of structural unit derived from the monomer having a hydroxyl group in the specific (meth) acrylic copolymer (A) / Monomer having a hydroxyl group in the specific (meth) acrylic copolymer (B) When the content of the structural unit derived from] is 1/200 or less on a mass basis, the specific (meth) acrylic copolymer (A) and the specific (meth) acrylic copolymer (B) are separated from each other. Properly cross-linked and the cohesive force becomes moderate. Therefore, it is possible to realize a pressure-sensitive adhesive layer having excellent high-temperature durability and glass warp suppressing property.

A single having a hydroxyl group in the specific (meth) acrylic copolymer (A) with respect to the content of the structural unit derived from the monomer having a hydroxyl group in the specific (meth) acrylic copolymer (C) described later. Percentage of Constituent Units Derived from Quantities [Contents of Constituent Units Derived from Monomers with Hydroxylates in the Specific (Meta) Acrylic Copolymer (A) / Specific (Meta) Acrylic Copolymers The content of the structural unit derived from the monomer having a hydroxyl group in the coalescence (C)] is 1/1 to 1/1000, preferably 1/10 to 1/700 on a mass basis. It is more preferably 1/20 to 1/400, and even more preferably 1/20 to 1/200.
[Content of structural unit derived from the monomer having a hydroxyl group in the specific (meth) acrylic copolymer (A) / Monomer having a hydroxyl group in the specific (meth) acrylic copolymer (C) When the content of the structural unit derived from the above is 1/1 or more on a mass basis, the viscoelasticity of the pressure-sensitive adhesive layer at room temperature (for example, 23 ° C.) is increased. Therefore, a pressure-sensitive adhesive layer having excellent processability can be realized.
[Content of structural unit derived from the monomer having a hydroxyl group in the specific (meth) acrylic copolymer (A) / Monomer having a hydroxyl group in the specific (meth) acrylic copolymer (C) When the content of the structural unit derived from the above is 1/1000 or less on a mass basis, the viscoelasticity of the pressure-sensitive adhesive layer at a high temperature (for example, 85 ° C. or higher) becomes low. Therefore, it is possible to realize an adhesive layer having excellent high temperature durability.

<Constituent unit derived from (meth) acrylic acid alkyl ester monomer>
The specific (meth) acrylic copolymer (A) contains 50% by mass or more of the structural units derived from the (meth) acrylic acid alkyl ester monomer with respect to all the structural units.
The structural unit derived from the (meth) acrylic acid alkyl ester monomer contributes to the adjustment of the adhesive strength of the pressure-sensitive adhesive layer.

As used herein, the "constituent unit derived from the (meth) acrylic acid alkyl ester monomer" means a structural unit formed by addition polymerization of the (meth) acrylic acid alkyl ester monomer.

The type of the (meth) acrylic acid alkyl ester monomer is not particularly limited.
As the (meth) acrylic acid alkyl ester monomer, an unsubstituted (meth) acrylic acid alkyl ester monomer is preferable, and an unsubstituted acrylic acid alkyl ester monomer is more preferable.
The alkyl group of the (meth) acrylic acid alkyl ester monomer may be linear, branched or cyclic.
The carbon number of the alkyl group is preferably in the range of 1 to 18 and more preferably in the range of 1 to 12 from the viewpoint of the adhesive force of the formed pressure-sensitive adhesive layer on the adherend and the adhesion to the substrate. ..

Examples of the (meth) acrylic acid alkyl ester monomer include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, s-butyl (meth) acrylate, and t. -Butyl (meth) acrylate, n-octyl (meth) acrylate, i-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-nonyl (meth) acrylate, i-nonyl (meth) acrylate, n-decyl Examples thereof include (meth) acrylate, n-dodecyl (meth) acrylate, stearyl (meth) acrylate, lauryl (meth) acrylate, cyclohexyl (meth) acrylate, and isobornyl (meth) acrylate.
Among these, the (meth) acrylic acid alkyl ester monomer is selected from the group consisting of, for example, methyl acrylate (MA), n-butyl acrylate (n-BA), and t-butyl acrylate (t-BA). At least one of these is preferred.

The specific (meth) acrylic copolymer (A) may contain only one type of structural unit derived from the (meth) acrylic acid alkyl ester monomer, or may contain two or more types.

The content (ratio) of the structural unit derived from the (meth) acrylic acid alkyl ester monomer in the specific (meth) acrylic copolymer (A) is the total content (ratio) of the specific (meth) acrylic copolymer (A). It is 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, based on the structural unit.
Here, the content (ratio) of the structural unit derived from the (meth) acrylic acid alkyl ester monomer is 50% by mass or more with respect to all the structural units of the specific (meth) acrylic copolymer (A). That is, it means that the structural unit derived from the (meth) acrylic acid alkyl ester monomer is contained as the main component of the structural unit constituting the specific (meth) acrylic copolymer (A). ..
The upper limit of the content (ratio) of the structural unit derived from the (meth) acrylic acid alkyl ester monomer in the specific (meth) acrylic copolymer (A) is not particularly limited, and for example, the specific (meth) acrylic. 99.5% by mass or less is preferable with respect to all the constituent units of the system copolymer (A).

<Constituent unit derived from a monomer having an aromatic ring>
The specific (meth) acrylic copolymer (A) may contain a structural unit derived from a monomer having an aromatic ring.
The structural unit derived from the monomer having an aromatic ring contributes to the improvement of optical properties.

As used herein, the "constituent unit derived from a monomer having an aromatic ring" means a structural unit formed by addition polymerization of a monomer having an aromatic ring.

The type of the monomer having an aromatic ring is not particularly limited.
Examples of the aromatic ring include a benzene ring.
Specific examples of the monomer having an aromatic ring include 2-phenoxyethyl (meth) acrylate and benzyl (meth) acrylate. Further, aromatic monovinyls (styrene, α-methylstyrene, t-butylstyrene, p-chlorostyrene, chloromethylstyrene, vinyltoluene, etc.) and various derivatives of these monomers are also mentioned.

When the specific (meth) acrylic copolymer (A) contains a structural unit derived from a monomer having an aromatic ring, the specific (meth) acrylic copolymer (A) may contain only one structural unit derived from the monomer having an aromatic ring. Well, it may contain two or more kinds.

When the specific (meth) acrylic copolymer (A) contains a structural unit derived from a monomer having an aromatic ring, the monomer having an aromatic ring in the specific (meth) acrylic copolymer (A) is used. The content rate (ratio) of the derived structural unit is not particularly limited, and is, for example, 10% by mass with respect to all the structural units of the specific (meth) acrylic copolymer (A) from the viewpoint of improving the optical characteristics. -20% by mass is preferable, 13% by mass to 20% by mass is more preferable, and 13% by mass to 15% by mass is further preferable.

<Other building blocks>
The specific (meth) acrylic copolymer (A) is the above-mentioned structural unit, that is, the structural unit derived from the monomer having a hydroxyl group, (meth) acrylic, within the range in which the effect of the present invention is exhibited. It may contain a structural unit other than the structural unit derived from the acid alkyl ester monomer and the structural unit derived from the monomer having an aromatic ring (so-called other structural units).

The type of the monomer constituting the other structural unit is not particularly limited.
Examples of the monomer constituting the other structural unit include a monomer having a carboxy group. Specific examples of the monomer having a carboxy group include acrylic acid (AA), methacrylic acid, and crotonic acid. Maleic anhydride, fumaric acid, itaconic acid, glutaconic acid, citraconic acid, ω-carboxy-polycaprolactone mono (meth) acrylate (eg, ω-carboxy-polycaprolactone (n≈2) monoacrylate), succinic acid ester (eg) , 2-Acryloyloxyethyl-succinic acid) and the like.
Among these, as the monomer having a carboxy group, for example, the viewpoint of reactivity with the isocyanate-based cross-linking agent described later and the wettability of the pressure-sensitive adhesive composition to the adherend are improved, and the pressure-sensitive adhesive layer is improved. Acrylic acid (AA) is preferred from the viewpoint that it can exhibit higher adhesive strength.

-Weight average molecular weight of the specific (meth) acrylic copolymer (A)-
The weight average molecular weight (Mw) of the specific (meth) acrylic copolymer (A) is in the range of 800,000 or more and less than 1.4 million, preferably in the range of 900,000 or more and 1.3 million or less, and preferably 900,000 or more and 1.2 million or less. The range is more preferred.
When the weight average molecular weight (Mw) of the specific (meth) acrylic copolymer (A) is 800,000 or more, a pressure-sensitive adhesive layer having excellent high-temperature durability can be formed.
When the weight average molecular weight (Mw) of the specific (meth) acrylic copolymer (A) is less than 1.4 million, a pressure-sensitive adhesive layer having excellent warp suppressing property of glass can be formed.

The weight average molecular weight (Mw) of the specific (meth) acrylic copolymer (A) is a value measured by the following method. Specifically, the measurement is performed according to the following (1) to (3).
(1) A solution of the specific (meth) acrylic copolymer (A) is applied to a release paper and dried at 100 ° C. for 1 minute to obtain a film-shaped specific (meth) acrylic copolymer (A).
(2) Using the film-shaped specific (meth) acrylic copolymer (A) obtained in (1) above and tetrahydrofuran is used, a sample solution having a solid content concentration of 0.2% by mass is obtained.
(3) Using gel permeation chromatography (GPC), the weight average molecular weight (Mw) of the specific (meth) acrylic copolymer (A) is measured as a standard polystyrene-equivalent value under the following conditions.

~ Conditions ~
Measuring device: High-speed GPC (Model number: HLC-8220 GPC, manufactured by Tosoh Corporation)
Detector: Differential refractometer (RI) (built into HLC-8220, manufactured by Tosoh Corporation)
Column: TSK-GEL GMHXL (manufactured by Tosoh Corporation) connected in series 4 Column temperature: 40 ° C
Eluent: Tetrahydrofuran Sample concentration: 0.2% by mass
Injection volume: 100 μL
Flow rate: 0.6 mL / min

For the weight average molecular weight (Mw) of the specific (meth) acrylic copolymer (A), the polymerization temperature, the polymerization time, the amount of the organic solvent used, the type of the polymerization initiator, the amount of the polymerization initiator used, etc. shall be adjusted. Therefore, the desired value can be obtained.

-Glass transition temperature of specific (meth) acrylic copolymer (A)-
The glass transition temperature (Tg) of the specific (meth) acrylic copolymer (A) is not particularly limited, and is, for example, preferably −25 ° C. or lower, more preferably −55 ° C. or higher and −25 ° C. or lower, −. A range of 50 ° C. or higher and −30 ° C. or lower is more preferable.
When the glass transition temperature (Tg) of the specific (meth) acrylic copolymer (A) is −25 ° C. or lower, the high temperature durability of the adhesive layer to be formed and the warp suppression property of the glass tend to be more excellent. show.

The glass transition temperature (Tg) of the specific (meth) acrylic copolymer (A) is a value obtained by converting the absolute temperature (K) obtained by calculation from the following formula 1 into the Celsius temperature (° C.).
1 / Tg = m1 / Tg1 + m2 / Tg2 + ... + m (k-1) / Tg (k-1) + mk / Tgk (Equation 1)

In the formula 1, Tg1, Tg2, ..., Tg (k-1), and Tgk are used when each monomer constituting the specific (meth) acrylic copolymer (A) is used as a homopolymer. It represents the glass transition temperature (Tg) represented by the absolute temperature (K), respectively. m1, m2, ..., m (k-1), and mk represent the mole fractions of each monomer constituting the specific (meth) acrylic copolymer (A), respectively, and m1 + m2 + ... + M (k-1) + mk = 1.
The absolute temperature (K) can be converted to the Celsius temperature (° C) by subtracting 273 from the absolute temperature (K), and the Celsius temperature (° C) can be converted to the absolute temperature (K) by adding 273 to the Celsius temperature (° C). Can be converted to.

The "glass transition temperature (Tg) when made into a homopolymer" is the glass transition temperature (Tg) represented by the absolute temperature (K) of the homopolymer produced by polymerizing the monomer alone. say.
The glass transition temperature (Tg) of the homopolymer was measured using a differential scanning calorimetry device (DSC) (model number: EXSTAR6000, Seiko Instruments Co., Ltd.) in a nitrogen stream, a measurement sample of 10 mg, and a temperature rise rate of 10 ° C./min. The change point of the obtained DSC curve was taken as the glass transition temperature (Tg) of the homopolymer.

The "glass transition temperature (Tg) represented by the Celsius temperature (° C) when made into a homopolymer" of a typical monomer is -76 ° C for 2-ethylhexyl acrylate (2EHA) and 2-ethylhexyl methacrylate (2-ethylhexyl methacrylate). 2EHMA) is -10 ° C, n-butyl acrylate (n-BA) is -57 ° C, n-butyl methacrylate is 21 ° C, t-butyl acrylate (t-BA) is 41 ° C, t-butyl methacrylate (t-BMA). ) Is 107 ° C, i-butyl methacrylate (i-BMA) is 48 ° C, methyl acrylate (MA) is 5 ° C, methyl methacrylate (MMA) is 103 ° C, isobonyl methacrylate (IBXMA) is 155 ° C, and isobonyl acrylate (isobonyl acrylate). IBXA) 96 ° C, ethyl acrylate (EA) -27 ° C, methacrylic acid 185 ° C, 4-hydroxybutyl acrylate (4HBA) -39 ° C, 2-hydroxyethyl acrylate (2HEA) -15 ° C, 2- Hydroxyethyl methacrylate (2HEMA) is 55 ° C, acrylic acid (AA) is 163 ° C, phenoxyethyl acrylate is -22 ° C, isooctyl acrylate (i-OA) is -75 ° C, and dimethylaminoethyl methacrylate (DM) is 18 ° C. , Trifluoroethyl methacrylate at 72 ° C, trifluoroethyl acrylate at -5 ° C, ω-carboxy-polycaprolactone (n≈2) monoacrylate at -30 ° C, 2-acryloyloxyethyl-succinic acid at -40 ° C. Is.

The glass transition temperature (Tg) of the specific (meth) acrylic copolymer (A) can be appropriately adjusted by using, for example, monomers having different glass transition temperatures (Tg) when used as a homopolymer.

-Contents of specific (meth) acrylic copolymer (A)-
The content of the specific (meth) acrylic copolymer (A) in the pressure-sensitive adhesive composition of the present invention is not particularly limited, and is, for example, 60% by mass to 94% by mass with respect to the total solid content in the pressure-sensitive adhesive composition. The mass% is preferable, 61% by mass to 80% by mass is more preferable, and 61% by mass to 76% by mass is further preferable.
A pressure-sensitive adhesive formed when the content of the specific (meth) acrylic copolymer (A) in the pressure-sensitive adhesive composition of the present invention is 60% by mass or more with respect to the total solid content in the pressure-sensitive adhesive composition. It shows a tendency that the warp suppression property of the layered glass is more excellent.
A pressure-sensitive adhesive formed when the content of the specific (meth) acrylic copolymer (A) in the pressure-sensitive adhesive composition of the present invention is 94% by mass or less with respect to the total solid content in the pressure-sensitive adhesive composition. The high temperature durability of the layer tends to be better.
In the present specification, the total solid content in the pressure-sensitive adhesive composition means the total mass of the pressure-sensitive adhesive composition when the pressure-sensitive adhesive composition does not contain a volatile component such as a solvent, and the pressure-sensitive adhesive composition. When contains a volatile component such as a solvent, it means the mass of the residue obtained by removing the volatile component such as a solvent from the pressure-sensitive adhesive composition.

[Specific (meth) acrylic copolymer (B)]
The (meth) acrylic copolymer (B) [that is, the specific (meth) acrylic copolymer (B)] contained in the pressure-sensitive adhesive composition of the present invention is a structural unit derived from a monomer having a hydroxyl group. , And 50% by mass or more of the structural units derived from the (meth) acrylic acid alkyl ester monomer with respect to all the structural units, and the weight average molecular weight is in the range of 1.4 million or more and 2 million or less.

<Constituent unit derived from a monomer having a hydroxyl group>
The specific (meth) acrylic copolymer (B) contains a structural unit derived from a monomer having a hydroxyl group.

Since the types and specific examples of the monomers having a hydroxyl group are as described above, the description thereof will be omitted here.
The preferred embodiment of the monomer having a hydroxyl group in the specific (meth) acrylic copolymer (B) and the reason thereof are the preferred embodiment of the monomer having a hydroxyl group in the specific (meth) acrylic copolymer (A) and the reason thereof. The reason is the same.

The specific (meth) acrylic copolymer (B) may contain only one type of structural unit derived from the monomer having a hydroxyl group, or may contain two or more types.

<Constituent unit derived from (meth) acrylic acid alkyl ester monomer>
The specific (meth) acrylic copolymer (B) contains 50% by mass or more of the structural units derived from the (meth) acrylic acid alkyl ester monomer with respect to all the structural units.
The structural unit derived from the (meth) acrylic acid alkyl ester monomer contributes to the adjustment of the adhesive strength of the pressure-sensitive adhesive layer.

Since the types and specific examples of the (meth) acrylic acid alkyl ester monomer are as described above, the description thereof will be omitted here.
The preferred embodiment of the (meth) acrylic acid alkyl ester monomer in the specific (meth) acrylic copolymer (B) and the reason thereof are the alkyl (meth) acrylic acid in the specific (meth) acrylic copolymer (A). This is the same as the preferred embodiment of the ester monomer and the reason thereof.

The specific (meth) acrylic copolymer (B) may contain only one type of structural unit derived from the (meth) acrylic acid alkyl ester monomer, or may contain two or more types.

The content (ratio) of the structural unit derived from the (meth) acrylic acid alkyl ester monomer in the specific (meth) acrylic copolymer (B) is the total content (ratio) of the specific (meth) acrylic copolymer (B). It is 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, based on the structural unit.
Here, the content (ratio) of the structural unit derived from the (meth) acrylic acid alkyl ester monomer is 50% by mass or more with respect to all the structural units of the specific (meth) acrylic copolymer (B). That is, it means that the structural unit derived from the (meth) acrylic acid alkyl ester monomer is contained as the main component of the structural unit constituting the specific (meth) acrylic copolymer (B). ..
The upper limit of the content (ratio) of the structural unit derived from the (meth) acrylic acid alkyl ester monomer in the specific (meth) acrylic copolymer (B) is not particularly limited, and for example, the specific (meth) acrylic. 99.5% by mass or less is preferable with respect to all the constituent units of the system copolymer (B).

<Constituent unit derived from a monomer having an aromatic ring>
The specific (meth) acrylic copolymer (B) preferably contains a structural unit derived from a monomer having an aromatic ring.
The structural unit derived from the monomer having an aromatic ring contributes to the improvement of optical properties.
In the pressure-sensitive adhesive composition of the present invention, either the specific (meth) acrylic copolymer (A) or the specific (meth) acrylic copolymer (B) is a monomer having an aromatic ring. It is preferable to include a structural unit derived from the specific (meth) acrylic copolymer (A) and the specific (meth) acrylic copolymer (B) both of which are derived from a monomer having an aromatic ring. It is more preferable to include the unit.

Since the types and specific examples of the monomers having an aromatic ring are as described above, the description thereof will be omitted here.

When the specific (meth) acrylic copolymer (B) contains a structural unit derived from a monomer having an aromatic ring, the specific (meth) acrylic copolymer (B) may contain only one structural unit derived from the monomer having an aromatic ring. Well, it may contain two or more kinds.

When the specific (meth) acrylic copolymer (B) contains a structural unit derived from a monomer having an aromatic ring, the monomer having an aromatic ring in the specific (meth) acrylic copolymer (B) is used. The content rate (ratio) of the derived structural unit is not particularly limited, and is, for example, 10% by mass with respect to all the structural units of the specific (meth) acrylic copolymer (B) from the viewpoint of improving the optical characteristics. It is preferably from 20% by mass, more preferably from 13% by mass to 20% by mass, still more preferably from 13% by mass to 15% by mass.

<Other building blocks>
The specific (meth) acrylic copolymer (B) is the above-mentioned structural unit, that is, the structural unit derived from the monomer having a hydroxyl group, (meth) acrylic, within the range in which the effect of the present invention is exhibited. It may contain a structural unit other than the structural unit derived from the acid alkyl ester monomer and the structural unit derived from the monomer having an aromatic ring (so-called other structural units).

Since the types and specific examples of the monomers constituting the other structural units are as described above, the description thereof will be omitted here.
A preferred embodiment of the monomer constituting the other structural unit in the specific (meth) acrylic copolymer (B) and the reason thereof constitute the other structural unit in the specific (meth) acrylic copolymer (A). This is the same as the preferred embodiment of the monomer to be used and the reason thereof.

-Weight average molecular weight of specific (meth) acrylic copolymer (B)-
The weight average molecular weight (Mw) of the specific (meth) acrylic copolymer (B) is in the range of 1.4 million or more and 2 million or less, preferably in the range of 1.4 million or more and 1.7 million or less, and preferably 1.4 million or more and 1.6 million or less. The range is more preferred.
When the weight average molecular weight (Mw) of the specific (meth) acrylic copolymer (B) is 1.4 million or more, a pressure-sensitive adhesive layer having excellent high-temperature durability can be formed.
When the weight average molecular weight (Mw) of the specific (meth) acrylic copolymer (B) is 2 million or less, a pressure-sensitive adhesive layer having excellent warp suppressing property of glass can be formed. In addition, the initial adhesive strength of the adhesive layer may be good.

The weight average molecular weight (Mw) of the specific (meth) acrylic copolymer (B) is measured by the same method as the weight average molecular weight (Mw) of the specific (meth) acrylic copolymer (A) described above. Value.

For the weight average molecular weight (Mw) of the specific (meth) acrylic copolymer (B), the polymerization temperature, the polymerization time, the amount of the organic solvent used, the type of the polymerization initiator, the amount of the polymerization initiator used, etc. shall be adjusted. Therefore, the desired value can be obtained.

-Glass transition temperature of specific (meth) acrylic copolymer (B)-
The glass transition temperature (Tg) of the specific (meth) acrylic copolymer (B) is not particularly limited, and is, for example, preferably −25 ° C. or lower, more preferably −55 ° C. or higher and −25 ° C. or lower, −. A range of 50 ° C. or higher and −30 ° C. or lower is more preferable.
When the glass transition temperature (Tg) of the specific (meth) acrylic copolymer (B) is −25 ° C. or lower, the high temperature durability of the adhesive layer to be formed and the warp suppression property of the glass tend to be more excellent. show.
In the pressure-sensitive adhesive composition of the present invention, the glass transition temperature of the specific (meth) acrylic copolymer (A) and the specific (meth) acrylic copolymer (B) are both −25 ° C. or lower. Is more preferable.
When the glass transition temperature of the specific (meth) acrylic copolymer (A) and the specific (meth) acrylic copolymer (B) are both -25 ° C or lower, the high temperature durability of the adhesive layer formed is high. And the warp suppressing property of the glass tends to be further excellent.

The glass transition temperature (Tg) of the specific (meth) acrylic copolymer (B) is measured by the same method as the glass transition temperature (Tg) of the specific (meth) acrylic copolymer (A) described above. Value.

The glass transition temperature (Tg) of the specific (meth) acrylic copolymer (B) can be appropriately adjusted by using, for example, monomers having different glass transition temperatures (Tg) when used as a homopolymer.

-Contents of specific (meth) acrylic copolymer (B)-
The content of the specific (meth) acrylic copolymer (B) in the pressure-sensitive adhesive composition of the present invention is not particularly limited, and is, for example, 4% by mass to 39% by mass with respect to the total solid content in the pressure-sensitive adhesive composition. The mass% is preferable, 10% by mass to 39% by mass is more preferable, and 12% by mass to 25% by mass is further preferable.
A pressure-sensitive adhesive formed when the content of the specific (meth) acrylic copolymer (B) in the pressure-sensitive adhesive composition of the present invention is 4% by mass or more with respect to the total solid content in the pressure-sensitive adhesive composition. The high temperature durability of the layer tends to be better.
A pressure-sensitive adhesive formed when the content of the specific (meth) acrylic copolymer (B) in the pressure-sensitive adhesive composition of the present invention is 39% by mass or less based on the total solid content in the pressure-sensitive adhesive composition. It shows a tendency that the warp suppression property of the layered glass is more excellent.

[Specific (meth) acrylic copolymer (C)]
The (meth) acrylic copolymer (C) [that is, the specific (meth) acrylic copolymer (C)] contained in the pressure-sensitive adhesive composition of the present invention is a structural unit derived from a monomer having a hydroxyl group. , And 50% by mass or more of the structural units derived from the (meth) acrylic acid alkyl ester monomer with respect to all the structural units, and the weight average molecular weight is in the range of 2,000 or more and 50,000 or less. ..

<Constituent unit derived from a monomer having a hydroxyl group>
The specific (meth) acrylic copolymer (C) contains a structural unit derived from a monomer having a hydroxyl group.

Since the types and specific examples of the monomers having a hydroxyl group are as described above, the description thereof will be omitted here.

As the monomer having a hydroxyl group, for example, hydroxyalkyl (meth) acrylate is preferable from the viewpoint of high temperature durability and good initial adhesive strength.
The preferred embodiment of the monomer having a hydroxyl group in the specific (meth) acrylic copolymer (C) and the reason thereof are the preferred embodiment of the monomer having a hydroxyl group in the specific (meth) acrylic copolymer (A) and the reason thereof. The reason is the same.

The specific (meth) acrylic copolymer (C) may contain only one type of structural unit derived from the monomer having a hydroxyl group, or may contain two or more types.

<Constituent unit derived from (meth) acrylic acid alkyl ester monomer>
The specific (meth) acrylic copolymer (C) contains 50% by mass or more of the structural units derived from the (meth) acrylic acid alkyl ester monomer with respect to all the structural units.
The structural unit derived from the (meth) acrylic acid alkyl ester monomer contributes to the adjustment of the adhesive strength of the pressure-sensitive adhesive layer.

Since the types and specific examples of the (meth) acrylic acid alkyl ester monomer are as described above, the description thereof will be omitted here.

As the (meth) acrylic acid alkyl ester monomer, an unsubstituted (meth) acrylic acid alkyl ester monomer is preferable, and an unsubstituted methacrylic acid alkyl ester monomer is more preferable.
Examples of the (meth) acrylic acid alkyl ester monomer include methyl methacrylate (MMA), t-butyl methacrylate (t-BMA), and i-butyl methacrylate (i) from the viewpoint of high glass transition temperature (Tg). -At least one selected from the group consisting of BMA) is preferable.

The specific (meth) acrylic copolymer (C) may contain only one type of structural unit derived from the (meth) acrylic acid alkyl ester monomer, or may contain two or more types.

The content (ratio) of the structural unit derived from the (meth) acrylic acid alkyl ester monomer in the specific (meth) acrylic copolymer (C) is the total content (ratio) of the specific (meth) acrylic copolymer (C). It is 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, based on the constituent unit.
Here, the content (ratio) of the structural unit derived from the (meth) acrylic acid alkyl ester monomer is 50% by mass or more with respect to all the structural units of the specific (meth) acrylic copolymer (C). That is, it means that the structural unit derived from the (meth) acrylic acid alkyl ester monomer is contained as the main component of the structural unit constituting the specific (meth) acrylic copolymer (C). ..
The upper limit of the content (ratio) of the structural unit derived from the (meth) acrylic acid alkyl ester monomer in the specific (meth) acrylic copolymer (C) is not particularly limited, and for example, the specific (meth) acrylic. It is preferably 99.95% by mass or less with respect to all the constituent units of the system copolymer (C).

<Other building blocks>
The specific (meth) acrylic copolymer (C) is the above-mentioned structural unit, that is, the structural unit derived from the monomer having a hydroxyl group, and (meth) within the range in which the effect of the present invention is exhibited. It may contain a structural unit (so-called other structural unit) other than the structural unit derived from the acrylic acid alkyl ester monomer.
The type of the monomer constituting the other structural unit is not particularly limited.

-Weight average molecular weight of specific (meth) acrylic copolymer (C)-
The weight average molecular weight (Mw) of the specific (meth) acrylic copolymer (C) is in the range of 2,000 or more and 50,000 or less, preferably in the range of 10,000 or more and 50,000 or less, and is 20,000 or more and 50,000. The following range is more preferable.
When the weight average molecular weight (Mw) of the specific (meth) acrylic copolymer (C) is 2,000 or more, a pressure-sensitive adhesive layer having excellent processability can be formed.
When the weight average molecular weight (Mw) of the specific (meth) acrylic copolymer (C) is 50,000 or less, a pressure-sensitive adhesive layer having excellent warp suppressing property of glass can be formed.

The weight average molecular weight (Mw) of the specific (meth) acrylic copolymer (C) is measured by the same method as the weight average molecular weight (Mw) of the specific (meth) acrylic copolymer (A) described above. Value.

For the weight average molecular weight (Mw) of the specific (meth) acrylic copolymer (C), the polymerization temperature, the polymerization time, the amount of the organic solvent used, the type of the polymerization initiator, the amount of the polymerization initiator used, etc. shall be adjusted. Therefore, the desired value can be obtained.

-Glass transition temperature of specific (meth) acrylic copolymer (C)-
The glass transition temperature (Tg) of the specific (meth) acrylic copolymer (C) is not particularly limited, and is, for example, preferably 70 ° C. or higher, more preferably 70 ° C. or higher and 100 ° C. or lower, and 80 ° C. or higher 100. The range of ° C. or lower is more preferable.
When the glass transition temperature (Tg) of the specific (meth) acrylic copolymer (C) is 70 ° C. or higher, the processability of the formed pressure-sensitive adhesive layer tends to be more excellent.

The glass transition temperature (Tg) of the specific (meth) acrylic copolymer (C) is measured by the same method as the glass transition temperature (Tg) of the specific (meth) acrylic copolymer (A) described above. Value.

The glass transition temperature (Tg) of the specific (meth) acrylic copolymer (C) can be appropriately adjusted by using, for example, monomers having different glass transition temperatures (Tg) when used as a homopolymer.

-Contents of specific (meth) acrylic copolymer (C)-
The content of the specific (meth) acrylic copolymer (C) in the pressure-sensitive adhesive composition of the present invention is not particularly limited, and is, for example, 1.5% by mass with respect to the total solid content in the pressure-sensitive adhesive composition. It is preferably from 20% by mass, more preferably 4% by mass to 20% by mass, still more preferably 7% by mass to 15% by mass.
It is formed when the content of the specific (meth) acrylic copolymer (C) in the pressure-sensitive adhesive composition of the present invention is 1.5% by mass or more with respect to the total solid content in the pressure-sensitive adhesive composition. It tends to have better processability of the pressure-sensitive adhesive layer.
A pressure-sensitive adhesive formed when the content of the specific (meth) acrylic copolymer (C) in the pressure-sensitive adhesive composition of the present invention is 20% by mass or less based on the total solid content in the pressure-sensitive adhesive composition. It shows a tendency that the warp suppression property of the layered glass is more excellent.

[Manufacturing method of specific (meth) acrylic copolymer]
Specific (meth) acrylic copolymer (A), specific (meth) acrylic copolymer (B), and specific (meth) acrylic copolymer (C) [that is, specific (meth) acrylic copolymer (that is, specific (meth) acrylic copolymer). The method for producing [coalescing] is not particularly limited.
The specific (meth) acrylic copolymer can be produced by polymerizing a monomer by a known polymerization method typified by, for example, a solution polymerization method, an emulsion polymerization method, a suspension polymerization method, and bulk polymerization.
Among these, as a polymerization method, solution polymerization is preferable because the treatment step is relatively simple and can be performed in a short time in preparing the pressure-sensitive adhesive composition of the present invention after production.

In solution polymerization, generally, a predetermined organic solvent, a monomer, a polymerization initiator, and a chain transfer agent used as needed are charged in a polymerization tank, and the mixture is stirred in a nitrogen stream or at the reflux temperature of the organic solvent. While heating for several hours. In this case, at least a part of the organic solvent, the monomer, the polymerization initiator and / or the chain transfer agent may be added sequentially.

Examples of the organic solvent used in the polymerization reaction include aromatic hydrocarbon compounds, aliphatic or alicyclic hydrocarbon compounds, ester compounds, ketone compounds, glycol ether compounds, alcohol compounds and the like.
More specifically, examples of the organic solvent used in the polymerization reaction include benzene, toluene, ethylbenzene, n-propylbenzene, t-butylbenzene, o-xylene, m-xylene, p-xylene, tetraline and decalin. And aromatic hydrocarbons represented by aromatic naphtha, n-hexane, n-heptane, n-octane, i-octane, n-decane, dipentene, petroleum spirit, petroleum naphtha, and fat represented by terepine oil. Ethers typified by system or alicyclic hydrocarbons, ethyl acetate, n-butyl acetate, n-amyl acetate, 2-hydroxyethyl acetate, 2-butoxyethyl acetate, 3-methoxybutyl acetate, and methyl benzoate. Classes, acetone, methyl ethyl ketone, methyl-i-butyl ketone, isophorone, cyclohexanone, and ketones typified by methylcyclohexanone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether. , And glycol ethers typified by diethylene glycol monobutyl ether, as well as methyl alcohol, ethyl alcohol, n-propyl alcohol, i-propyl alcohol, n-butyl alcohol, i-butyl alcohol, s-butyl alcohol, and t-. Examples thereof include alcohols typified by butyl alcohol.
At the time of the polymerization reaction, only one of these organic solvents may be used, or two or more of these organic solvents may be mixed and used.

In the production of the specific (meth) acrylic copolymer, it is preferable to use an organic solvent that does not easily cause chain transfer during the polymerization reaction of aromatic hydrocarbons, esters, ketones, etc., and in particular, the specific (meth) acrylic. From the viewpoint of solubility of the system copolymer, ease of polymerization reaction and the like, it is preferable to use ethyl acetate, butyl acetate, toluene, methyl ethyl ketone and the like.

Examples of the polymerization initiator include organic peroxides and azo compounds used in ordinary solution polymerization.
Examples of the organic peroxide include t-butyl hydroperoxide, cumene hydroperoxide, dicumyl peroxide, benzoyl peroxide, lauroyl peroxide, caproyl peroxide, di-i-propylperoxydicarbonate, and di-2-ethylhexylperoxydi. Carbonate, t-butylperoxypivalate, 2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane, 2,2-bis (4,4-di-t-amylperoxycyclohexyl) propane, 2,2-bis (4,4-di-t-octylperoxycyclohexyl) propane, 2,2-bis (4,4-di-α-cumylperoxycyclohexyl) propane, 2,2-bis (4,4) -Di-t-butylperoxycyclohexyl) butane and 2,2-bis (4,4-di-t-octylperoxycyclohexyl) butane can be mentioned.
Examples of the azo compound include 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis (2,4-dimethylvaleronitrile) (ABVN), and 2,2'-azobis (4-). Methoxy-2,4-dimethylvaleronitrile), 1,1'-azobis (cyclohexane-1-carbonitrile), and 2,2'-azobis (isobutyric acid) dimethyl.

In the production of the specific (meth) acrylic copolymer, it is preferable to use a polymerization initiator that does not cause a graft reaction during the polymerization reaction, and in particular, it is preferable to use an azobis-based polymerization initiator.

The amount of the polymerization initiator used is not particularly limited, and is appropriately set according to the molecular weight of the target specific (meth) acrylic copolymer.

In the production of the specific (meth) acrylic copolymer, a chain transfer agent may be used, if necessary, as long as the object and effect of the present invention are not impaired.
Examples of the chain transfer agent include cyanoacetic acid, alkyl esters of cyanoacetic acid having 1 to 8 carbon atoms, bromoacetic acid, alkyl esters of bromoacetic acid having 1 to 8 carbon atoms, α-methylstyrene, anthracene, phenanthrene, and fluorene. , And aromatic compounds such as 9-phenylfluorene, p-nitroaniline, nitrobenzene, dinitrobenzene, p-nitrobenzoic acid, p-nitrophenol, and aromatic nitro compounds such as p-nitrotoluene, Benzoquinone and benzoquinone derivatives typified by 2,3,5,6-tetramethyl-p-benzoquinone, borane derivatives typified by tributylborane, carbon tetrabromide, carbon tetrachloride, 1,1,2,2- Tetrabromoester, tribromoethylene, trichloroethylene, bromotrichloromethane, tribromomethane, halogenated hydrocarbons typified by 3-chloro-1-propene, aldehydes typified by chloral and furaldehide, carbon number 1 to 1 to 18 alkyl mercaptans, aromatic mercaptans typified by thiophenols and toluene mercaptans, mercaptoacetic acid, alkyl esters of mercaptoacetic acid with 1 to 10 carbon atoms, hydroxyalkyl mercaptans with 1 to 12 carbon atoms, and binen. And terpenes typified by tarpinolene.

When a chain transfer agent is used in the production of the specific (meth) acrylic copolymer, the amount of the chain transfer agent used is not particularly limited and depends on the molecular weight of the target specific (meth) acrylic copolymer. , Set as appropriate.

The polymerization temperature is not particularly limited and is appropriately set according to the molecular weight of the target specific (meth) acrylic copolymer.

[Isocyanate-based cross-linking agent]
The pressure-sensitive adhesive composition of the present invention contains an isocyanate-based cross-linking agent.
As used herein, the term "isocyanate-based cross-linking agent" means a compound having two or more isocyanate groups in the molecule (so-called polyisocyanate compound).

Examples of the polyisocyanate compound include aromatic polyisocyanate compounds such as xylylene diisocyanate (XDI), diphenylmethane diisocyanate, triphenylmethane triisocyanate, and tolylene diisocyanate (TDI), hexamethylene diisocyanate (HMDI), and pentamethylene diisocyanate (PDI). , Isophoron diisocyanate, aliphatic or alicyclic polyisocyanate compounds such as hydrogenated additives of aromatic polyisocyanate compounds and the like.
Examples of the polyisocyanate compound include a dimer, a trimer, or a pentamer of the polyisocyanate compound, an adduct of the polyisocyanate compound and a polyol compound such as trimethylolpropane, and a biuret of the isocyanate compound. Can also be mentioned.
Among these, hexamethylene diisocyanate (HMDI) is preferable as the polyisocyanate compound, for example, from the viewpoint of being able to form a pressure-sensitive adhesive layer having improved high-temperature durability, processability, and glass warpage suppression property in a more balanced manner. ..

As the polyisocyanate compound, a commercially available product can be used.
Examples of commercially available polyisocyanate compounds are "Coronate (registered trademark) HX", "Coronate (registered trademark) HL-S", "Coronate (registered trademark) L", and "Coronate (registered trademark) L-45E". , "Coronate® 2031", "Coronate® 2030", "Coronate® 2234", "Coronate® 2785", "Aquanate® 200", and "Aqua". Nate (registered trademark) 210 ”[above, Tosoh Co., Ltd.],“ Sumijuru (registered trademark) N3300 ”,“ Death Module (registered trademark) N3400 ”, and“ Sumijuru (registered trademark) N-75 ”[more than , Sumika Cobestro Urethane Co., Ltd.], "Duranate (registered trademark) E-405-80T", "Duranate (registered trademark) AE700-100", "Duranate (registered trademark) 24A-100", and "Duranate (registered trademark) "TSE-100" [above, Asahi Kasei Co., Ltd.], "Takenate (registered trademark) D-110N", "Takenate (registered trademark) D-120N", "Takenate (registered trademark) M-631N" , "MT-Orester (registered trademark) NP1200", and "Stavio (registered trademark) XD-340N" [above, Mitsui Kagaku Co., Ltd.].

The pressure-sensitive adhesive composition of the present invention may contain only one type of isocyanate-based cross-linking agent, or may contain two or more types.

The content of the isocyanate-based cross-linking agent in the pressure-sensitive adhesive composition of the present invention is not particularly limited, and for example, the specific (meth) acrylic copolymer (A), the specific (meth) acrylic copolymer (B), and the like. And 1.3 parts by mass to 8.0 parts by mass, preferably 1.5 parts by mass to 6.0 parts by mass with respect to 100 parts by mass of the total content of the specific (meth) acrylic copolymer (C). More preferably, it is more preferably 2.0 parts by mass to 6.0 parts by mass.
The content of the isocyanate-based cross-linking agent in the pressure-sensitive adhesive composition of the present invention is the specific (meth) acrylic copolymer (A), the specific (meth) acrylic copolymer (B), and the specific (meth) acrylic copolymer. When the total content of the copolymer (C) is 1.3 parts by mass or more with respect to 100 parts by mass, the cohesive force of the pressure-sensitive adhesive layer becomes more moderately high, and the processability tends to be more excellent.
The content of the isocyanate-based cross-linking agent in the pressure-sensitive adhesive composition of the present invention is the specific (meth) acrylic copolymer (A), the specific (meth) acrylic copolymer (B), and the specific (meth) acrylic copolymer. When the total content of the copolymer (C) is 8.0 parts by mass or less with respect to 100 parts by mass, the cohesive force of the pressure-sensitive adhesive layer does not become too high, and the high-temperature durability and the warp suppressing property of the glass are more excellent. Show a trend.

[Organic solvent]
The pressure-sensitive adhesive composition of the present invention may contain an organic solvent, for example, from the viewpoint of improving coatability.
Examples of the organic solvent include the same organic solvents as those used in the polymerization reaction of the above-mentioned specific (meth) acrylic copolymer.

When the pressure-sensitive adhesive composition of the present invention contains an organic solvent, it may contain only one kind of organic solvent or two or more kinds.

When the pressure-sensitive adhesive composition of the present invention contains an organic solvent, the content of the organic solvent is not particularly limited and can be appropriately set depending on the intended purpose.

[Other ingredients]
The pressure-sensitive adhesive composition of the present invention may contain components other than the above-mentioned components (so-called other components), if necessary, as long as the effects of the present invention are not impaired.
Other components include polymers other than the specific (meth) acrylic copolymer (A), the specific (meth) acrylic copolymer (B), and the specific (meth) acrylic copolymer (C). Cross-linking agents other than isocyanate-based cross-linking agents, cross-linking catalysts, silane coupling agents, tackifiers, antioxidants, colorants (eg dyes and pigments), light stabilizers (eg UV absorbers), antistatic agents, etc. Examples include various additives.

When the pressure-sensitive adhesive composition of the present invention contains these other components, the content of the other components can be appropriately set within the range in which the effects of the present invention are exhibited.

[Use of adhesive composition]
The pressure-sensitive adhesive composition of the present invention is suitably used for applications in which a polarizing plate is attached to an adherend via a pressure-sensitive adhesive layer. Specific examples thereof include an application in which a polarizing plate is attached to a liquid crystal cell, an application in which a polarizing plate is attached to an optical film such as a retardation film, and the like.
Among these, the effect of the pressure-sensitive adhesive composition of the present invention is more exhibited when it is used for attaching a polarizing plate to a liquid crystal cell, which is particularly required to have high temperature durability, processability, and glass warpage suppression property. Therefore, it is preferable.

[Polarizer with adhesive layer]
The polarizing plate with a pressure-sensitive adhesive layer of the present invention includes a polarizing plate and a pressure-sensitive adhesive layer provided on the above-mentioned polarizing plate and formed by the above-mentioned pressure-sensitive adhesive composition of the present invention.
Since the polarizing plate with a pressure-sensitive adhesive layer of the present invention includes the pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition of the present invention, it is excellent in high-temperature durability and processability. Further, according to the polarizing plate with an adhesive layer of the present invention, for example, even if it is attached to the glass substrate of a liquid crystal cell, the glass is less likely to warp.

The polarizing plate in the present invention is configured to include at least a polarizing element, may be a single polarizing element, or may be a laminate of a polarizing element and a protective film.
That is, the polarizing plate may have a one-layer structure of a single stator, a two-layer structure having a protective film on one side of the polarizing element, or a three-layer structure having protective films on both sides of the polarizing element. There may be.

The layer structure of the polarizing plate with a pressure-sensitive adhesive layer of the present invention includes, for example, a pressure-sensitive adhesive layer / a polarizing element, a pressure-sensitive adhesive layer / a polarizing element / a protective film, a pressure-sensitive adhesive layer / a protective film / a polarizing element / a protective film, and a pressure-sensitive adhesive. Examples include layer / protective film / polarizing element.
An optical functional layer typified by a retardation film (for example, an EWV layer) between the polarizing element and the protective film, between the protective film and the pressure-sensitive adhesive layer, and between the polarizing element and the pressure-sensitive adhesive layer. It may have a layer such as an adhesive layer and an easy-adhesive layer).
Further, the outermost surface of the polarizing plate with the pressure-sensitive adhesive layer may be protected by a release film.

Examples of the splitter include polyvinyl alcohol (PVA) film.

Examples of the protective film include triacetyl cellulose (TAC) film, polycycloolefin (COP) film, polyethylene terephthalate (PET) film, and acrylic film.

As a release film that protects the surface on the pressure-sensitive adhesive layer side, in order to make it easy to peel off the release film from the pressure-sensitive adhesive layer, for example, a mold release agent such as a fluororesin, paraffin wax, or silicone is used to perform a mold release treatment on the surface. A synthetic resin film such as a resin film is preferably used.
When the surface opposite to the surface on the pressure-sensitive adhesive layer side is protected by a release film, examples of the release film include a surface protective film such as a hard-coated polyethylene terephthalate (PET) film.

The thickness of the pressure-sensitive adhesive layer in the polarizing plate with a pressure-sensitive adhesive layer of the present invention can be appropriately set according to the types of the base material and the adherend, the surface roughness of the base material and the adherend, and the like. Generally, the thickness of the pressure-sensitive adhesive layer is 1 μm to 100 μm, preferably 5 μm to 50 μm, and more preferably 10 μm to 30 μm.

The polarizing plate with an adhesive layer of the present invention can be produced by a known method.
As a known method, for example, the pressure-sensitive adhesive composition of the present invention is applied onto a release film, dried, a coating layer of the pressure-sensitive adhesive composition is formed on the release film, and then the coating layer is transferred onto a polarizing plate. , A method of producing a polarizing plate with an adhesive layer by curing it can be mentioned.
Further, the pressure-sensitive adhesive composition of the present invention is applied onto a release film and dried to form a coating layer of the pressure-sensitive adhesive composition on the release film, and then the release film is provided in close contact with the exposed surface of the coating layer. Make a double-sided adhesive tape without a support. Next, the coating layer is cured to form an adhesive layer. Next, a method of producing a polarizing plate with a pressure-sensitive adhesive layer by peeling off one of the release films and transferring the exposed pressure-sensitive adhesive layer onto the polarizing plate can be mentioned.
Further, a method of producing a polarizing plate with a pressure-sensitive adhesive layer by applying the pressure-sensitive adhesive composition of the present invention on a polarizing plate, drying and curing the polarizing plate can be mentioned.
Examples of the drying condition include a condition of drying at 70 ° C. to 120 ° C. for 1 minute to 3 minutes using a hot air dryer.

Hereinafter, the present invention will be described in more detail with reference to Examples. The present invention is not limited to the following examples as long as the gist is not exceeded.

The weight average molecular weight (Mw) of the (meth) acrylic copolymer (A), the (meth) acrylic copolymer (B), and the (meth) acrylic copolymer (C) produced in this example. ) Was measured by the method described above.
Further, the glass transition temperature (Tg) of the (meth) acrylic copolymer (A), the (meth) acrylic copolymer (B), and the (meth) acrylic copolymer (C) produced in this example. ) Was calculated by the method described above.

[Manufacturing of (meth) acrylic copolymer (A)]
[Manufacturing Example A1]
59.95 parts by mass of n-butyl acrylate (n-BA), 15.0 parts by mass of phenoxyethyl acrylate (PHEA), methyl in a reactor equipped with a thermometer, a stirrer, a nitrogen introduction tube, and a reflux cooling tube. After adding 24.7 parts by mass of acrylate (MA), 0.3 parts by mass of acrylic acid (AA), 0.05 parts by mass of 2-hydroxyethyl acrylate (2HEA), and 130.0 parts by mass of ethyl acetate and mixing. The inside of the reactor was replaced with nitrogen. Then, the mixture in the reactor was heated to 70 ° C. with stirring, and then 0.002 parts by mass of 2,2'-azobis (2,4-dimethylvaleronitrile) (ABVN; polymerization initiator) and 50 parts of ethyl acetate. .0 parts by mass was sequentially added and held for 6 hours for polymerization reaction. After completion of the polymerization reaction, the mixture was diluted with ethyl acetate to adjust the solid content to 22.0% by mass to obtain a solution of the (meth) acrylic copolymer A1.
The term "solid content" as used herein means a residue obtained by removing volatile components such as a solvent from the solution of the (meth) acrylic copolymer A1. The same applies to the following (meth) acrylic copolymers A2 to A11.
The (meth) acrylic copolymer A1 had a weight average molecular weight (Mw) of 1,000,000 and a glass transition temperature (Tg) of −35 ° C.

[Manufacturing Examples A2 to A5]
In Production Example A1, the weight average molecular weight (Mw) was changed as shown in Table 1 by adjusting the amount of the organic solvent (that is, ethyl acetate) and the amount of the polymerization initiator (that is, ABVN). Except for the above, the same operation as in Production Example A1 was carried out to obtain solutions of the (meth) acrylic copolymers A2 to A5.

[Manufacturing Examples A6 to A11]
In Production Example A1, the same operations as in Production Example A1 were carried out except that the monomer composition was changed to the monomer composition shown in Table 1, and the solutions of the (meth) acrylic copolymers A6 to A11 were prepared. Obtained.

(Meta) Acrylic copolymers A1 to A11 monomer composition (unit: mass%), weight average molecular weight [Mw, unit: 10,000 (indicated as "× 10 ⁴ " in Table 1)], and glass. The transition temperature (Tg, unit: ° C.) is shown in Table 1.
In Table 1, "t-BA" represents "t-butyl acrylate", "2HEMA" represents "2-hydroxyethyl methacrylate", and "4HBA" represents "4-hydroxybutyl acrylate".

[Manufacturing of (meth) acrylic copolymer (B)]
[Manufacturing Example B1]
In a reactor equipped with a thermometer, stirrer, nitrogen introduction tube, and reflux cooling tube, 62.0 parts by mass of n-butyl acrylate (n-BA), 15.0 parts by mass of phenoxyethyl acrylate (PHEA), methyl. After adding 22.2 parts by mass of acrylate (MA), 0.3 parts by mass of acrylic acid (AA), 0.5 parts by mass of 2-hydroxyethyl acrylate (2HEA), and 150.0 parts by mass of ethyl acetate and mixing. The inside of the reactor was replaced with nitrogen. Then, the mixture in the reactor was heated to 70 ° C. with stirring, and then 0.06 parts by mass of 2,2'-azobis (2,4-dimethylvaleronitrile) (ABVN; polymerization initiator) and 50 parts of ethyl acetate were added. .0 parts by mass was sequentially added and held for 6 hours for polymerization reaction. After completion of the polymerization reaction, the mixture was diluted with ethyl acetate to adjust the solid content to 20.0% by mass to obtain a solution of the (meth) acrylic copolymer B1. The term "solid content" as used herein means a residue obtained by removing volatile components such as a solvent from the solution of the (meth) acrylic copolymer B1. The same applies to the following (meth) acrylic copolymers B2 to B15.
The (meth) acrylic copolymer B1 had a weight average molecular weight (Mw) of 1.5 million and a glass transition temperature (Tg) of −37 ° C.

[Manufacturing Examples B2 to B5]
In Production Example B1, the weight average molecular weight (Mw) was changed as shown in Table 2 by adjusting the amount of the organic solvent (that is, ethyl acetate) and the amount of the polymerization initiator (that is, ABVN). Except for the above, the same operation as in Production Example B1 was carried out to obtain solutions of the (meth) acrylic copolymers B2 to B5.

[Manufacturing Examples B6 to B15]
In Production Example B1, the same operations as in Production Example B1 were carried out except that the monomer composition was changed to the monomer composition shown in Table 2, and the solutions of the (meth) acrylic copolymers B6 to B15 were prepared. Obtained.

(Meta) Acrylic copolymers B1 to B15 monomer composition (unit: mass%), weight average molecular weight [Mw, unit: 10,000 (indicated as "× 10 ⁴ " in Table 2)], and glass. The transition temperature (Tg, unit: ° C.) is shown in Table 2.
In Table 2, "t-BA" represents "t-butyl acrylate", "2HEMA" represents "2-hydroxyethyl methacrylate", and "4HBA" represents "4-hydroxybutyl acrylate".

[Manufacturing of (meth) acrylic copolymer (C)]
[Manufacturing Example C1]
In a reactor equipped with a thermometer, a stirrer, and a reflux cooling tube, 22.0 parts by mass of ethyl acetate and 17.0 parts by mass of butyl acetate were placed and heated, and under reflux temperature conditions, methyl methacrylate (MMA) 69. 0.0 parts by mass, 1.0 part by mass of t-butyl methacrylate (t-BMA), 29.0 parts by mass of i-butyl methacrylate (i-BMA), and 1.0 part by mass of 2-hydroxyethyl methacrylate (2HEMA). 7. Parts, ethyl acetate 18.0 parts by mass, butyl acetate 5.0 parts by mass, and 2,2'-azobis (methyl isobutyrate) [trade name: V-601, Fujifilm Wako Junyaku Co., Ltd.] 7. A polymerization initiator solution consisting of 0 parts by mass was sequentially added dropwise over 3 hours to cause a polymerization reaction. After completion of the polymerization reaction, the mixture was diluted with ethyl acetate to adjust the solid content to 50.0% by mass to obtain a solution of the (meth) acrylic copolymer C1. The term "solid content" as used herein means a residue obtained by removing volatile components such as a solvent from the solution of the (meth) acrylic copolymer C1. The same applies to the following (meth) acrylic copolymers C2 to C15.
The (meth) acrylic copolymer C1 had a weight average molecular weight (Mw) of 5,000 and a glass transition temperature (Tg) of 89 ° C.

[Manufacturing Examples C2 to C5]
In Production Example C1, the weight average molecular weight (Mw) is shown in Table 3 by adjusting the amount of the organic solvent (that is, ethyl acetate and butyl acetate) and the amount of the polymerization initiator (that is, V-601). The same operation as in Production Example C1 was carried out except that the above was changed, and solutions of the (meth) acrylic copolymers C2 to C5 were obtained.

[Manufacturing Examples C6 to C15]
In Production Example C1, the same operation as in Production Example C1 was performed except that the monomer composition was changed to the monomer composition shown in Table 3, and each solution of the (meth) acrylic copolymers C6 to C15 was prepared. Obtained.

(Meta) Acrylic copolymers C1 to C15 monomer composition (unit: mass%), weight average molecular weight [Mw, unit: 10,000 (indicated as "× 10 ⁴ " in Table 3)], and glass. The transition temperature (Tg, unit: ° C.) is shown in Table 3.
In Table 3, "2HEA" represents "2-hydroxyethyl acrylate" and "4HBA" represents "4-hydroxybutyl acrylate".

[Example 1]
<Preparation of adhesive composition>
The mass ratio (A1 / B1 / C1) of the (meth) acrylic copolymer A1, the (meth) acrylic copolymer B1 and the (meth) acrylic copolymer C1 in terms of solid content is 85/15. The mixture was mixed so as to be 1/10 to obtain a polymer mixed solution.
With respect to 100 parts by mass (solid content conversion value) of the obtained polymer mixture, an isocyanate-based cross-linking agent [trade name: Sumijuru (registered trademark) N3300, hexamethylene diisocyanate (HMDI), solid content: 100% by mass, Sumitomo Polymerized Cobestrolurethane Co., Ltd.] 3.0 parts by mass was added and mixed well to prepare a pressure-sensitive adhesive composition.

<Manufacturing of polarizing plate with adhesive layer>
Using the pressure-sensitive adhesive composition obtained above, a polarizing plate with a pressure-sensitive adhesive layer was prepared as follows.
A pressure-sensitive adhesive on the surface-treated surface of a release film surface-treated with a silicone-based mold release agent [trade name: Film Vina (registered trademark) 100E-0010N023, Fujimori Kogyo Co., Ltd.] so that the thickness after drying is 20 μm. The composition was applied to form a coating film. Next, the formed coating film was dried at a drying temperature of 100 ° C. for 90 seconds using a hot air circulation type dryer to form an adhesive film on the release film. Next, one surface of the polarizing plate having a laminated structure of the triacetyl cellulose (TAC) layer / polyvinyl alcohol (PVA) layer / TAC layer and the surface of the adhesive film layer formed on the release film are overlapped and bonded. After that, it was passed through a pressurized nip roll and crimped. After crimping, autoclave treatment (temperature: 50 ° C., pressure: 5 kg / cm ² , treatment time: 20 minutes) was applied, and then the mixture was cured in an environment with an ambient temperature of 23 ° C. and 50% RH for 96 hours to release the film / adhesive. A polarizing plate with an adhesive layer having a laminated structure of an agent layer / a polarizing plate was produced.

[Examples 2 to 15]
In Examples 2 to 15, the same operations as in Example 1 were performed except that the composition of the pressure-sensitive adhesive composition was changed to the composition shown in Table 4, to prepare a pressure-sensitive adhesive composition and to prepare a polarizing plate with a pressure-sensitive adhesive layer. Was produced.

[Examples 16 to 34]
In Examples 16 to 34, the same operations as in Example 1 were performed except that the composition of the pressure-sensitive adhesive composition was changed to the composition shown in Table 5, to prepare a pressure-sensitive adhesive composition and to prepare a polarizing plate with a pressure-sensitive adhesive layer. Was produced.

[Comparative Examples 1 to 14]
In Comparative Examples 1 to 14, the same operations as in Example 1 were carried out except that the composition of the pressure-sensitive adhesive composition was changed to the composition shown in Table 6, to prepare a pressure-sensitive adhesive composition and to prepare a polarizing plate with a pressure-sensitive adhesive layer. Was produced.

[evaluation]
1. 1. High temperature durability The polarizing plate with an adhesive layer produced above was cut so that the long side was 45 ° with respect to the absorption axis, and a test piece having a size of 50 mm × 89 mm (long side) was obtained.
The release film of the test piece was peeled off, and the surface of the pressure-sensitive adhesive layer exposed by the peeling was made of glass [trade name: Eagle XG (registered trademark), thickness: 0.7 mm, Corning Inc .; the same applies hereinafter. ] Was laminated on one side and crimped using a laminator to prepare a laminated body. The prepared laminate was subjected to autoclave treatment (temperature: 50 ° C., pressure: 5 kg / cm ² , treatment time: 20 minutes), and then left in an environment with an ambient temperature of 23 ° C. and 65% RH for 1 hour. A sample for high temperature durability evaluation was obtained.
The obtained high-temperature durability evaluation sample was placed in an incubator kept at 85 ° C. and left for 168 hours. After the elapse of the standing time, a sample for high temperature durability evaluation was taken out from the incubator and the appearance was visually observed. Then, the high temperature durability was evaluated according to the following evaluation criteria. The results are shown in Tables 4-6.
If the evaluation result is "A", "B", or "C", there is no practical problem.

-Evaluation criteria-
A: No foaming, floating, or peeling was observed.
B: Almost no foaming, floating, or peeling was observed.
C: Some foaming, floating, and peeling were observed, but it was within the allowable range.
D: Foaming, floating, and peeling were observed, which was out of the allowable range.

2. 2. Workability The polarizing plate with an adhesive layer produced above was cut so that the long side was 45 ° with respect to the absorption axis, and a test piece having a size of 59 mm × 89 mm (long side) was obtained. The obtained test piece was used as a sample for workability evaluation.
Using a cutting blade in which 10 Thomson blades were stacked, cutting of the sample for workability evaluation was repeated 10 times. After cutting 10 times, the appearance of the cutting blade was visually observed, and the workability was evaluated according to the following evaluation criteria. The results are shown in Tables 4-6.
If the evaluation result is "A", "B", or "C", there is no practical problem.

-Evaluation criteria-
A: No adhesive residue was observed.
B: Almost no adhesive residue was observed.
C: A small amount of adhesive residue was observed, but it was within the allowable range.
D: Adhesive residue was observed and was out of the allowable range.

3. 3. Inhibitory of glass warpage The polarizing plate with an adhesive layer produced above was cut so that the long side was 90 ° with respect to the absorption axis, and a test piece having a size of 50 mm × 160 mm (long side) was obtained. rice field.
The release film of the test piece was peeled off, and the surface of the pressure-sensitive adhesive layer exposed by the peeling was laminated on one side of the glass and pressure-bonded using a laminator to prepare a laminated body. The prepared laminate was subjected to autoclave treatment (temperature: 50 ° C., pressure: 5 kg / cm ² , treatment time: 20 minutes), and then left in an environment with an ambient temperature of 23 ° C. and 65% RH for 1 hour. A sample for warpage evaluation was obtained.
The prepared sample for warp evaluation was placed in an incubator kept at 85 ° C. and left for 168 hours. After the elapse of the standing time, a sample for warp evaluation was taken out from the incubator, and the degree of warp was measured using a laser displacement meter [trade name: LK-H027, KEYENCE Co., Ltd.]. Then, the warp suppressing property of the glass was evaluated according to the following evaluation criteria. The results are shown in Tables 4-6.
If the evaluation result is "A", "B", or "C", there is no practical problem.

-Evaluation criteria-
A: The warp is less than 1.0 mm.
B: The warp is in the range of 1.0 mm or more and less than 1.5 mm.
C: The warp is in the range of 1.5 mm or more and less than 2.0 mm.
D: The warp is 2.0 mm or more.

4. Initial adhesive strength (preparation of sample for adhesive strength evaluation)
The polarizing plate with the pressure-sensitive adhesive layer produced above was cut so that the long side was 45 ° with respect to the absorption axis, and a test piece having a size of 25 mm × 150 mm (long side) was obtained. The obtained test piece was used as a sample for evaluation of adhesive strength.
The release film of the sample for adhesive strength evaluation was peeled off, the surface of the pressure-sensitive adhesive layer exposed by the peeling was laminated on one side of the glass and bonded, and pressure-bonded using a laminator to prepare a test piece. Then, the prepared test piece was left in an environment of an atmospheric temperature of 23 ° C. and 50% RH for 24 hours.
After the elapse of the standing time, a single column type material testing machine (model number: STA-1225) of A & D Co., Ltd. was used as a measuring device, and the peeling speed was 300 mm under an environment of an atmospheric temperature of 23 ° C. and 50% RH. The adhesive strength evaluation sample (adhesive layer / base material) was peeled 180 ° in the long side (150 mm) direction from the stainless steel plate under the condition of / minute, and the adhesive strength (unit: N / 25 mm) was measured. Then, the initial adhesive strength was evaluated according to the following evaluation criteria. The results are shown in Tables 4-6.
If the evaluation result is "A", "B", or "C", there is no practical problem.

-Evaluation criteria-
A: The initial adhesive strength is 5N / 25mm or more.
B: The initial adhesive strength is in the range of 3N / 25mm or more and less than 5N / 25mm.
C: The initial adhesive strength is in the range of 1N / 25mm or more and less than 3N / 25mm.
D: The initial adhesive strength is less than 1N / 25 mm.

In Tables 4 to 6, "(meth) acrylic copolymer" is referred to as "copolymer".
In Tables 4 to 6, "the content (unit: parts by mass) of the structural unit derived from the monomer having a hydroxyl group in the (meth) acrylic copolymer" is expressed as "the amount of hydroxyl group".
In Tables 4 to 6, "the ratio of the content (unit: parts by mass) of the structural unit derived from the monomer having a hydroxyl group in the (meth) acrylic copolymer" is referred to as "hydroxyl group ratio".
"-" In Table 6 means that there is no corresponding item.
In Table 6, "TH-130" and "D-6011" marked with "*" are not copolymers, but are described in the "C" column of "Type of copolymer" for convenience. ing.

Details of the components listed in Tables 4 to 6 are as follows.
<Adhesive-imparting resin (tack fire)>
"TH-130": YS Polystar TH130 [Product name, Yasuhara Chemical Co., Ltd.]
"D-6011": D-6011 [Product name, Arakawa Chemical Industry Co., Ltd.]
<Crosslinking agent>
-Isocyanate cross-linking agent-
"Coronate L": Coronate (registered trademark) L [trade name, adduct of toluene diisocyanate (TDI) and trimethylolpropane (TMP), solid content: 75% by mass, Tosoh Corporation]
"AE700-100": Duranate (registered trademark) AE700-100 [trade name, hexamethylene diisocyanate (HMDI), solid content: 100% by mass, Asahi Kasei Corporation]
-Metal chelate cross-linking agent-
"Aluminum Chelate A": Aluminum Chelate A [Product Name, Aluminum Tris Acetylacetone, Kawaken Fine Chemical Co., Ltd.]
-Epoxy cross-linking agent-
"TETRAD-X": TETRAD (registered trademark) -X [trade name, solid content: 100% by mass, Mitsubishi Gas Chemical Company, Inc.]

As shown in Tables 4 and 5, the pressure-sensitive adhesive layers formed by the pressure-sensitive adhesive compositions of Examples 1 to 34 are all excellent in high-temperature durability, processability, and glass warpage suppressing property. have understood.
In addition, the pressure-sensitive adhesive layers formed by the pressure-sensitive adhesive compositions of Examples 1 to 34 all showed good initial adhesive strength.

On the other hand, as shown in Table 6, the pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive compositions of Comparative Examples 1 to 14 was inferior in at least one of high-temperature durability, processability, and glass warpage inhibitory property. ..

Claims (7)

It contains a structural unit derived from a monomer having a hydroxyl group and a structural unit derived from a (meth) acrylic acid alkyl ester monomer in an amount of 50% by mass or more based on all the structural units, and has a weight average molecular weight of 80. With the (meth) acrylic copolymer (A) in the range of 10,000 or more and less than 1.4 million,
It contains a structural unit derived from a monomer having a hydroxyl group and a structural unit derived from a (meth) acrylic acid alkyl ester monomer in an amount of 50% by mass or more based on all the structural units, and has a weight average molecular weight of 140. With the (meth) acrylic copolymer (B) in the range of 10,000 or more and 2 million or less,
It contains a structural unit derived from a monomer having a hydroxyl group and a structural unit derived from a (meth) acrylic acid alkyl ester monomer in an amount of 50% by mass or more based on all the structural units, and has a weight average molecular weight of 0. . With the (meth) acrylic copolymer (C) in the range of 20,000 or more and 50,000 or less,
Contains an isocyanate-based cross-linking agent,
The single having the hydroxyl group in the (meth) acrylic copolymer (A) with respect to the content of the structural unit derived from the monomer having the hydroxyl group in the (meth) acrylic copolymer (B). The ratio of the content of the constituent units derived from the polymer is 1/1 to 1/200 on a mass basis.
A single having the hydroxyl group in the (meth) acrylic copolymer (A) with respect to the content of the structural unit derived from the monomer having the hydroxyl group in the (meth) acrylic copolymer (C). A pressure-sensitive adhesive composition for a polarizing plate, wherein the content ratio of the structural unit derived from the polymer is 1/1 to 1/1000 on a mass basis. The adhesive for a polarizing plate according to claim 1, wherein the (meth) acrylic copolymer (A) and the (meth) acrylic copolymer (B) both have a glass transition temperature of −25 ° C. or lower. Agent composition. The pressure-sensitive adhesive composition for a polarizing plate according to claim 1 or 2, wherein the glass transition temperature of the (meth) acrylic copolymer (C) is 70 ° C. or higher. The content of the isocyanate-based cross-linking agent is the same as that of the (meth) acrylic copolymer (A), the (meth) acrylic copolymer (B), and the (meth) acrylic copolymer (C). The pressure-sensitive acrylic composition according to any one of claims 1 to 3, which is 1.3 parts by mass to 8.0 parts by mass with respect to 100 parts by mass of the total content. The single having the hydroxyl group in the (meth) acrylic copolymer (A) with respect to the content of the structural unit derived from the monomer having the hydroxyl group in the (meth) acrylic copolymer (B). The ratio of the content of the constituent units derived from the polymer is 1/5 to 1/200 on a mass basis.
The single having the hydroxyl group in the (meth) acrylic copolymer (A) with respect to the content of the structural unit derived from the monomer having the hydroxyl group in the (meth) acrylic copolymer (C). The pressure-sensitive adhesive composition for a polarizing plate according to any one of claims 1 to 4, wherein the content ratio of the structural unit derived from the polymer is 1/10 to 1/700 on a mass basis. .. Claims 1 to claim that at least one of the (meth) acrylic copolymer (A) and the (meth) acrylic copolymer (B) contains a structural unit derived from a monomer having an aromatic ring. Item 5. The pressure-sensitive adhesive composition for a polarizing plate according to any one of Item 5. With a polarizing plate
A pressure-sensitive adhesive layer provided on the polarizing plate and formed of the pressure-sensitive adhesive composition for a polarizing plate according to any one of claims 1 to 6.
A polarizing plate with an adhesive layer.