JP6096617B2 - Adhesive composition and optical functional film - Google Patents

Description

  The present invention relates to an adhesive composition and an optical functional film.

  As display devices for displaying images, such as liquid crystal display devices and organic electroluminescence display devices, devices of various display methods are widely used. Among these, a liquid crystal display device generally includes a liquid crystal cell in which a liquid crystal component oriented in a predetermined direction is sandwiched between two supporting substrates such as glass, and an optical film such as a polarizing plate, a retardation film, and a brightness enhancement film. Are bonded together. An adhesive is used when laminating optical films or sticking an optical film to a liquid crystal cell.

  Liquid crystal display devices are widely used as display devices for televisions, personal computers, car navigation systems, and the like. For example, various liquid crystal display devices such as harsh environmental conditions with a high amount of moisture at high temperature and high humidity and dry environmental conditions at low humidity. Used under environmental conditions. Therefore, even when used for a long period of time, the bonded portion bonded with the adhesive, that is, the interface between the adhesive layer and the polarizing film is not peeled off, or the adhesive layer does not break, It is required that the pressure-sensitive adhesive layer has high durability such that bubbles are not easily generated.

  As a pressure-sensitive adhesive composition with improved durability, a mixture of acrylic copolymers having different reactive functional groups is cross-linked with an isocyanate compound, so that it floats even after heat treatment and high-humidity treatment, A pressure-sensitive adhesive composition that can suppress the occurrence of defects in the pressure-sensitive adhesive layer such as peeling has been proposed (see, for example, Patent Document 1).

  In addition, the polarizing plate has a polarizing film (polarizer) using PVA or the like, but when a stretched film is used for this polarizing film, for example, when exposed to a severe environment such as high temperature and high humidity, A dimensional change accompanying shrinkage and expansion tends to occur, and stress is generated in the polarizing plate. When the stress accompanying the dimensional change is not relaxed by the adhesive disposed between the polarizing plate and the liquid crystal cell, the residual stress is unevenly generated in the polarizing plate. As a result, a phase shift occurs between the two polarizing plates arranged so that the extending axes of the polarizing film intersect each other on the front and back surfaces of the display panel, and light is emitted from the four periphery of the display unit of the liquid crystal display device. Unevenness (light leakage) called so-called “white spots” occurs, which leaks and becomes white.

  Crosslinkable acrylic copolymer and non-crosslinkable acrylic copolymer having a (meth) acrylic acid ester monomer and an aromatic group-containing monomer as an adhesive composition for suppressing the occurrence of light leakage Has been proposed (for example, see Patent Document 2).

JP 2008-45048 A Special table 2011-510114 gazette

However, the actual situation is that no adhesive composition having high durability and suppressing light leakage has been found.
The present invention has high durability in which generation of foaming and peeling is suppressed even under severe environmental conditions of high temperature and high humidity or high temperature and low humidity, and environmental conditions in which the temperature or humidity changes rapidly, and light leakage occurs. It is an object of the present invention to provide a pressure-sensitive adhesive composition in which the pressure is suppressed and an optical functional film using the pressure-sensitive adhesive composition.

  The present invention relates to an acrylic copolymer containing a specific amount of a structural unit derived from a monomer having a hydroxyl group, a structural unit derived from a monomer having an aromatic ring, and a structural unit derived from an alkyl (meth) acrylate. What was achieved based on the knowledge that A and the acrylic copolymer B and the isocyanate compound were combined to obtain a high durability and the ability to suppress light leakage. It is.

Specific means for solving the above problems are as follows.
<1> Acrylic copolymer A containing a structural unit derived from a monomer having a hydroxyl group, a structural unit derived from a monomer having an aromatic ring, and a structural unit derived from an alkyl (meth) acrylate, and a hydroxyl group An acrylic copolymer B comprising a structural unit derived from a monomer having a structural unit derived from a monomer having an aromatic ring, and a structural unit derived from an alkyl (meth) acrylate, an isocyanate compound, And the content of the structural unit derived from the monomer having a hydroxyl group in the acrylic copolymer A (I) [mol%] and the monomer having a hydroxyl group in the acrylic copolymer B The content (II) [mol%] of the derived structural unit satisfies the relationship represented by the following formula (1) and has an aromatic ring of the acrylic copolymer A and the acrylic copolymer B. Of structural units derived from monomers A pressure-sensitive adhesive composition in which the total amount (III) [mol%] satisfies the relationship represented by the following formula (2).
(II)-(I)> 0 mol% (1)
(III) ≧ 3 mol% (2)

<2> The content (I) of the structural unit derived from the monomer having a hydroxyl group in the acrylic copolymer A is 0.01 mol% or more and less than 2.4 mol%, and the acrylic copolymer B The pressure-sensitive adhesive composition according to <1>, wherein the content (II) of the structural unit derived from the monomer having a hydroxyl group content is 1.2 mol% or more and 10.0 mol% or less.
<3> Content (I) of constituent unit derived from a monomer having a hydroxyl group in the acrylic copolymer A and constituent unit derived from a monomer having a hydroxyl group in the acrylic copolymer B The pressure-sensitive adhesive composition according to <1> or <2>, wherein the difference ((II)-(I)) from the content (II) is 0.1 mol% to 10.0 mol%.

<4> The pressure-sensitive adhesive composition according to any one of <1> to <3>, wherein the acrylic copolymer A and the acrylic copolymer B have a weight average molecular weight of 500,000 or more.
<5> Any one of <1> to <4>, wherein a mixing ratio (A / B) of the acrylic copolymer A to the acrylic copolymer B is 90/10 to 50/50 on a mass basis. The adhesive composition as described in one.
<6> The addition amount of the isocyanate compound is 0.10 parts by mass to 1.00 parts by mass with respect to 100 parts by mass of the total amount of the acrylic copolymer A and the acrylic copolymer B < The pressure-sensitive adhesive composition according to any one of 1> to <5>.

<7> The structure derived from the alkyl (meth) acrylate whose carbon number of the structural unit derived from the alkyl (meth) acrylate of the said acrylic copolymer A and the said acrylic copolymer B is 1-6. The pressure-sensitive adhesive composition according to any one of <1> to <6>, which is a unit.
<8> The structural unit derived from the monomer having a hydroxyl group of the acrylic copolymer A and the acrylic copolymer B is a structural unit derived from a (meth) acrylic monomer <1>. ~ <7> The pressure-sensitive adhesive composition according to any one of the above.
<9> The structural unit derived from the monomer having an aromatic ring of the acrylic copolymer A and the acrylic copolymer B is a structural unit derived from a (meth) acrylic monomer <1. The pressure-sensitive adhesive composition according to any one of> to <8>.

<10> An optical functionality comprising: a polarizing base film; and an adhesive layer provided on the polarizing base film and derived from the adhesive composition according to any one of <1> to <9>. the film.

  According to the present invention, it has high durability in which the occurrence of foaming and peeling is suppressed even under severe environmental conditions of high temperature and high humidity or high temperature and low humidity, and environmental conditions in which the temperature or humidity changes suddenly. The adhesive composition which can suppress generation | occurrence | production of an optical function, and the optical functional film using this adhesive composition can be provided.

Hereinafter, the pressure-sensitive adhesive composition of the present invention and the optical functional film using the same will be described in detail.
In the present specification, the content of each component in the composition is the total amount of the plurality of substances present in the composition unless there is a specific notice when there are a plurality of substances corresponding to each component in the composition. means.
Moreover, (meth) acrylate means at least one of acrylate and methacrylate, and (meth) acryl means at least one of acrylic and methacryl.
Moreover, the numerical value range shown using "to" in this specification shows the range which includes the numerical value described before and behind "to" as a minimum value and a maximum value, respectively.

<Adhesive composition>
The pressure-sensitive adhesive composition of the present invention comprises an acrylic copolymer comprising a structural unit derived from a monomer having a hydroxyl group, a structural unit derived from a monomer having an aromatic ring, and a structural unit derived from an alkyl (meth) acrylate. An acrylic copolymer B comprising a polymer A, a structural unit derived from a monomer having a hydroxyl group, a structural unit derived from a monomer having an aromatic ring, and a structural unit derived from an alkyl (meth) acrylate; , An isocyanate compound, and a content (I) of a structural unit derived from a monomer having a hydroxyl group in the acrylic copolymer A and a single amount having a hydroxyl group in the acrylic copolymer B. Monomer having an aromatic ring of the acrylic copolymer A and the acrylic copolymer B, wherein the content (II) of the structural unit derived from the body satisfies the relationship represented by the following formula (1) Total amount of structural units derived from (I Satisfy the relationship I) is represented by the following formula (2).
(II)-(I)> 0 mol% (1)
(III) ≧ 3 mol% (2)

  In addition to the acrylic copolymer A, the acrylic copolymer B, and the isocyanate compound, the pressure-sensitive adhesive composition of the present invention may further include a crosslinking agent, a silane coupling agent, and other additions as necessary. Components such as agents may be included.

Conventionally, a technology for forming a pressure-sensitive adhesive using a plurality of types of copolymers having different molecular weights is known, but simply reducing the molecular weight of some of the copolymers may cause light leakage such as white spots. On the other hand, although the improvement effect by stress relaxation can be expected, the durability is remarkably lowered and the occurrence of foaming or peeling cannot be suppressed.
In the present invention, an acrylic copolymer having a different content of structural units derived from a monomer having a hydroxyl group is mixed at a specific ratio, and the acrylic copolymer is crosslinked with a predetermined amount of an isocyanate compound. Thus, high durability can be obtained that can suppress the occurrence of foaming or peeling even against deformation of the polarizing base film due to a sudden change in environmental conditions. Moreover, when the acrylic copolymer contains a predetermined amount of a structural unit derived from a monomer having an aromatic ring, light leakage such as white spots can be suppressed.

Although the action mechanism of the present invention is not clear, the present inventors presume as follows.
In the present invention, the content of the structural unit derived from the monomer having a hydroxyl group contained in the acrylic copolymer, the molecular weight of the acrylic copolymer, the mixing ratio of the acrylic copolymer, the blending of the isocyanate compound By setting the amount to a specific amount, the pressure-sensitive adhesive composition has excellent balance between elasticity and viscosity, and the content of the structural unit derived from the monomer having a hydroxyl group contained in the acrylic copolymer is Stress relaxation occurs in a small portion of the acrylic copolymer A, and adhesion occurs in a portion of the acrylic copolymer B having a high content of structural units derived from a monomer having a hydroxyl group contained in the acrylic copolymer. By obtaining an appropriate cohesive force as the agent composition, it is considered that the pressure-sensitive adhesive composition can follow the deformation of the polarizing base film due to environmental changes and suppress the occurrence of foaming and peeling.

Each component is described in detail below.
In the present specification, the acrylic copolymer A and the acrylic copolymer B are collectively referred to as an acrylic copolymer as appropriate.

-Acrylic copolymer A-
The pressure-sensitive adhesive composition of the present invention comprises an acrylic copolymer comprising a structural unit derived from a monomer having a hydroxyl group, a structural unit derived from a monomer having an aromatic ring, and a structural unit derived from an alkyl (meth) acrylate. Contains at least one polymer A. The acrylic copolymer A is a copolymer of at least a structural unit derived from a monomer having a hydroxyl group, a structural unit derived from a monomer having an aromatic ring, and a structural unit derived from an alkyl (meth) acrylate. It is also possible to copolymerize structural units derived from other monomers.

  The acrylic copolymer A may be a random copolymer or a block copolymer, but is preferably a random copolymer.

  The acrylic copolymer A contains at least one structural unit derived from a monomer having a hydroxyl group. By including a structural unit derived from a monomer having a hydroxyl group, the cohesive force of the pressure-sensitive adhesive composition is improved, durability is improved, and light leakage can be suppressed when applied to an optical functional film. it can.

The monomer having a hydroxyl group contained in the acrylic copolymer A is not particularly limited as long as it is a polymerizable compound having at least one hydroxyl group in one molecule and copolymerizable with an alkyl (meth) acrylate. Absent. The number of hydroxyl groups in one molecule of the monomer having a hydroxyl group is not particularly limited, but is preferably 1.
From the viewpoint of compatibility with other structural units, the structural unit derived from a monomer having a hydroxyl group is preferably a structural unit derived from a (meth) acrylic monomer having a hydroxyl group, and has a hydroxyl group (meth). A structural unit derived from an acrylate ester is more preferable.
Examples of monomers having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 3-methyl. -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, polypropylene glycol mono (meth) acrylate, polyethylene glycol mono (meth) acrylate, poly (ethylene glycol-propylene glycol) mono (meth) acrylate, and the like.
Among them, hydroxyalkyl (meth) acrylate is preferable in that it has high polymerization reactivity and excellent crosslinking reactivity when the composition containing the obtained copolymer is used, and the hydroxyalkyl having 1 to 4 carbon atoms in the alkyl moiety. (Meth) acrylate is more preferable, and 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and 4-hydroxybutyl acrylate are more preferable.
Monomers having a hydroxyl group may be used alone or in combination of two or more.

  The content of the structural unit derived from the monomer having a hydroxyl group in the acrylic copolymer A is preferably 0.01 mol% or more and less than 2.4 mol%, more preferably 0.1 mol% to 2.0 mol%. 0.1 mol% to 1.0 mol% is more preferable. When the content of the constitutional unit derived from the monomer having a hydroxyl group is within the above range, temperature or humidity when mixed with an acrylic copolymer B and an isocyanate compound described later to form an adhesive composition It is possible to relieve the stress of the polarizer caused by the change in the thickness, which is advantageous for suppressing light leakage, and further, the pressure-sensitive adhesive composition can be adjusted to the optimum viscoelasticity, which is also advantageous in terms of durability. It is.

  The monomer having an aromatic ring contained in the acrylic copolymer A is not particularly limited as long as it is a polymerizable compound having at least one aromatic ring in the molecule and copolymerizable with an alkyl (meth) acrylate. Absent. The cyclic group in the monomer having an aromatic ring is preferably an aromatic hydrocarbon group having 6 to 10 carbon atoms. The content of the aromatic ring in the monomer having an aromatic ring is preferably 1 to 2, and more preferably 1.

As the structural unit derived from a monomer having an aromatic ring, a structural unit derived from a (meth) acrylic monomer having an aromatic ring is preferable from the viewpoint of compatibility with other structural units.
Examples of the monomer having an aromatic ring include phenoxyethyl (meth) acrylate, benzyl (meth) acrylate, 2-phenylthio-1-ethyl acrylate, 8- (2-naphthyloxy) -1-octyl acrylate, 2- (1-naphthyloxy) -1-ethyl acrylate and the like.
Among these, phenoxyethyl (meth) acrylate and benzyl (meth) acrylate are preferable from the viewpoint of copolymerizability, and phenoxyethyl acrylate and benzyl acrylate are more preferable.
The monomer which has an aromatic ring may be used individually by 1 type, or may be used in combination of 2 or more type.

  The content of the structural unit derived from the monomer having an aromatic ring in the acrylic copolymer A is the total amount of the structural unit derived from the monomer having an aromatic ring of the acrylic copolymer B described later. The amount is 3 mol% or more, but from the viewpoint of suppressing light leakage, 3 mol% or more is preferable, 5 mol% to 20 mol% is more preferable, and 10 mol% to 20 mol% is still more preferable.

  The acrylic copolymer A contains at least one structural unit derived from alkyl (meth) acrylate. The alkyl group in the alkyl (meth) acrylate may be linear or branched, but does not contain an aromatic ring. The number of carbon atoms of the alkyl group is preferably 1-20, more preferably 1-18, still more preferably 1-12, and particularly preferably 1-6.

Examples of the alkyl (meth) acrylate contained in the acrylic copolymer A include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, 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 ( And (meth) acrylate, n-dodecyl (meth) acrylate, stearyl (meth) acrylate, and the like. Among them, from the viewpoint of easily adjusting the cohesive force and adhesive force of the pressure-sensitive adhesive, an alkyl (meth) acrylate having 1 to 6 carbon atoms is preferable, an alkyl acrylate having 1 to 6 carbon atoms is more preferable, and n-butyl acrylate is particularly preferable. preferable.
The said alkyl (meth) acrylate may be used individually by 1 type, or may be used in combination of 2 or more type.

  The structural unit derived from the alkyl (meth) acrylate is contained as a main component constituting the acrylic copolymer A. The content of the structural unit derived from the alkyl (meth) acrylate in the acrylic copolymer A is preferably 65 mol% to 99.5 mol%, more preferably 65 mol% to 94 mol%, and particularly preferably 75 mol% to 86 mol%. . When the content of the structural unit derived from the alkyl (meth) acrylate is within the above range, it can be adjusted to an optimal elastic modulus, which is advantageous in terms of ensuring durability and tackiness.

The acrylic copolymer A is included as a structural unit derived from a monomer having a hydroxyl group, a structural unit derived from a monomer having an aromatic ring, a structural unit derived from an alkyl (meth) acrylate, and as necessary. In addition to the structural unit, a structural unit derived from another monomer other than these may be included.
Other monomers include monomers having an acidic group such as acrylic acid, methacrylic acid, and ω-carboxypolycaprolactone mono (meth) acrylate; aminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, dimethyl Monomers having basic groups such as aminopropyl (meth) acrylate and vinylpyridine; vinyl cyanide monomers such as acrylonitrile and methacrylonitrile; vinyls such as vinyl formate, vinyl acetate, vinyl propionate and vinyl versatate An ester monomer etc. can be mentioned.
Among these, from the viewpoint of adhesion to the substrate, a monomer having an acidic group is preferable, and acrylic acid is more preferable. The content of the monomer having an acidic group in the acrylic copolymer A is preferably 0.5 mol% to 5 mol%, and more preferably 3 mol% to 5 mol%. When the content of the monomer having an acidic group is within the above range, the adhesiveness to the substrate is excellent, which is advantageous in terms of durability.

  The weight average molecular weight of the acrylic copolymer A is preferably 500,000 or more, and more preferably 1,000,000 or more. When the acrylic copolymer A has a weight average molecular weight of 500,000 or more, peeling or the like hardly occurs and durability is improved.

  The glass transition temperature (TgA) of the acrylic copolymer A is preferably in the range of −50 ° C. or higher and −30 ° C. or lower, and more preferably in the range of −48 ° C. or higher and −35 ° C. or lower. When TgA is −50 ° C. or higher, the elastic modulus can be adjusted to the optimum, and the durability and light leakage suppression are excellent. Moreover, when TgA is −30 ° C. or lower, the tackiness and bonding suitability are excellent without significantly impairing the viscosity.

  The content of the acrylic copolymer A in the pressure-sensitive adhesive composition may be appropriately selected within a range that satisfies the mixing ratio (A / B) of the acrylic copolymer A to the acrylic copolymer B described later. Although it can, The range of 50 mass parts or more and 90 mass parts or less is preferable with respect to the total solid of an adhesive composition. When the content of the acrylic copolymer A is within the above range, the pressure-sensitive adhesive composition is given flexibility, and the occurrence of light leakage is suppressed by stress relaxation.

-Acrylic copolymer B-
The pressure-sensitive adhesive composition of the present invention comprises an acrylic copolymer comprising a structural unit derived from a monomer having a hydroxyl group, a structural unit derived from a monomer having an aromatic ring, and a structural unit derived from an alkyl (meth) acrylate. Contains at least one polymer B. This acrylic copolymer B is a copolymer of at least a structural unit derived from a monomer having a hydroxyl group, a structural unit derived from a monomer having an aromatic ring, and a structural unit derived from an alkyl (meth) acrylate. It is also possible to copolymerize structural units derived from other monomers.

  The acrylic copolymer B may be a random copolymer or a block copolymer, but is preferably a random copolymer.

  The acrylic copolymer B contains at least one structural unit derived from a monomer having a hydroxyl group. By including the structural unit derived from the monomer having a hydroxyl group, the cohesive force as the pressure-sensitive adhesive composition is improved, and the durability can be improved.

The monomer having a hydroxyl group contained in the acrylic copolymer B is not particularly limited as long as it is a polymerizable compound having at least one hydroxyl group in one molecule and copolymerizable with an alkyl (meth) acrylate. Absent. The number of hydroxyl groups in one molecule of the monomer having a hydroxyl group is not particularly limited, but is preferably 1.
From the viewpoint of copolymerization, the structural unit derived from a monomer having a hydroxyl group is preferably a structural unit derived from a (meth) acrylic monomer having a hydroxyl group, and derived from a (meth) acrylic acid ester having a hydroxyl group. The structural unit is more preferable.
Examples of monomers having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 3-methyl. -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, polypropylene glycol mono (meth) acrylate, polyethylene glycol mono (meth) acrylate, poly (ethylene glycol-propylene glycol) mono (meth) acrylate, and the like.
Among them, hydroxyalkyl (meth) acrylate is preferable in that it has high polymerization reactivity and excellent crosslinking reactivity when the composition containing the obtained copolymer is used, and the hydroxyalkyl having 1 to 4 carbon atoms in the alkyl moiety. (Meth) acrylate is more preferable, and 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and 4-hydroxybutyl acrylate are more preferable.
Monomers having a hydroxyl group may be used alone or in combination of two or more.

  The content of the structural unit derived from the monomer having a hydroxyl group in the acrylic copolymer B is preferably 1.2 mol% to 10.0 mol%, more preferably 1.2 mol% to 5.0 mol%. More preferably, it is 2 mol% to 2.5 mol%. When the content of the constitutional unit derived from the monomer having a hydroxyl group is within the above range, the durability when the pressure-sensitive adhesive composition is mixed with the acrylic copolymer A and the isocyanate compound is improved. .

  The monomer having an aromatic ring contained in the acrylic copolymer B is not particularly limited as long as it is a polymerizable compound having at least one aromatic ring in the molecule and copolymerizable with an alkyl (meth) acrylate. Absent. The cyclic group in the monomer having an aromatic ring is preferably an aromatic hydrocarbon group having 6 to 10 carbon atoms. The content of the aromatic ring in the monomer having an aromatic ring is preferably 1 to 2, and more preferably 1.

As the structural unit derived from a monomer having an aromatic ring, a structural unit derived from a (meth) acrylic monomer having an aromatic ring is preferable from the viewpoint of compatibility with other structural units. Examples of the monomer having an aromatic ring include phenoxyethyl (meth) acrylate, benzyl (meth) acrylate, 2-phenylthio-1-ethyl acrylate, 8- (2-naphthyloxy) -1-octyl acrylate, 2- (1-naphthyloxy) -1-ethyl acrylate and the like.
Among these, phenoxyethyl (meth) acrylate and benzyl (meth) acrylate are preferable from the viewpoint of copolymerizability, and phenoxyethyl acrylate and benzyl acrylate are more preferable.
The monomer which has an aromatic ring may be used individually by 1 type, or may be used in combination of 2 or more type.

  The content of the structural unit derived from the monomer having an aromatic ring in the acrylic copolymer B is 3 mol in total with the structural unit derived from the monomer having an aromatic ring of the acrylic copolymer A. From the viewpoint of suppressing light leakage, 3 mol% or more is preferable, 5 mol% to 20 mol% is more preferable, and 10 mol% to 20 mol% is still more preferable.

  The acrylic copolymer B contains at least one structural unit derived from an alkyl (meth) acrylate. The alkyl group in the alkyl (meth) acrylate may be linear or branched, but does not contain an aromatic ring. The number of carbon atoms of the alkyl group is preferably 1-20, more preferably 1-18, still more preferably 1-12, and particularly preferably 1-6.

  Examples of the alkyl (meth) acrylate contained in the acrylic copolymer B include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, 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 ( And (meth) acrylate, n-dodecyl (meth) acrylate, stearyl (meth) acrylate, and the like. Among them, from the viewpoint of easily adjusting the cohesive force and adhesive force of the pressure-sensitive adhesive, an alkyl (meth) acrylate having 1 to 6 carbon atoms is preferable, an alkyl acrylate having 1 to 6 carbon atoms is more preferable, and n-butyl acrylate is particularly preferable. preferable.

  The structural unit derived from the alkyl (meth) acrylate is contained as a main component constituting the acrylic copolymer B. The content of the structural unit derived from the alkyl (meth) acrylate in the acrylic copolymer B is preferably 65 mol% to 98.5 mol%, more preferably 65 mol% to 93 mol%, and particularly preferably 75 mol% to 85 mol%. preferable. When the content of the structural unit derived from the alkyl (meth) acrylate is within the above range, it can be adjusted to an optimal elastic modulus, which is advantageous in terms of ensuring durability and tackiness.

The acrylic copolymer B is included in a structural unit derived from a monomer having a hydroxyl group, a structural unit derived from a monomer having an aromatic ring, a structural unit derived from an alkyl (meth) acrylate, and as necessary. In addition to the structural unit, a structural unit derived from another monomer other than these may be included.
Other monomers include monomers having an acidic group such as acrylic acid, methacrylic acid, and ω-carboxypolycaprolactone mono (meth) acrylate; aminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, dimethyl Monomers having basic groups such as aminopropyl (meth) acrylate and vinylpyridine; vinyl cyanide monomers such as acrylonitrile and methacrylonitrile; vinyls such as vinyl formate, vinyl acetate, vinyl propionate and vinyl versatate An ester monomer etc. can be mentioned.
Among these, from the viewpoint of adhesion to the substrate, a monomer having an acidic group is preferable, and acrylic acid is more preferable. The content of the monomer having an acidic group in the acrylic copolymer B is preferably 0.5 mol% to 5 mol%, and more preferably 3 mol% to 5 mol%. When the content of the monomer having an acidic group is within the above range, the adhesiveness to the substrate is excellent, which is advantageous in terms of durability.

  The weight average molecular weight of the acrylic copolymer B is preferably 500,000 or more, and more preferably 1,000,000 or more. When the weight average molecular weight of the acrylic copolymer B is 500,000 or more, peeling or the like hardly occurs, and durability is improved.

  The glass transition temperature (TgB) of the acrylic copolymer B is preferably in the range of −50 ° C. to −30 ° C., more preferably in the range of −48 ° C. to −35 ° C. When TgB is −50 ° C. or higher, the elastic modulus can be adjusted to an optimum value, and the durability and light leakage suppression are excellent. Moreover, when TgA is −30 ° C. or lower, the tackiness and bonding suitability are excellent without significantly impairing the viscosity.

  The content of the acrylic copolymer B in the pressure-sensitive adhesive composition can be appropriately selected as long as the ratio (A / B) of the acrylic copolymer A to the acrylic copolymer B described later is satisfied. However, the range of 10 mass parts or more and 50 mass parts or less is preferable with respect to the total solid of an adhesive composition. When the content of the acrylic copolymer B is within the above range, the durability of the pressure-sensitive adhesive composition is improved, and the occurrence of foaming and peeling is suppressed.

  In the acrylic copolymer A and the acrylic copolymer B in the present invention, a structural unit derived from a monomer having a hydroxyl group constituting each, a structural unit derived from a monomer having an aromatic ring, and an alkyl (meta) ) The structural unit derived from the acrylate may be different or the same in the acrylic copolymer A and the acrylic copolymer B.

Content (I) mol% of structural unit derived from monomer having hydroxyl group in acrylic copolymer A and content of structural unit derived from monomer having hydroxyl group in acrylic copolymer B (II) mol% satisfies the relationship of the following formula (1).
(II)-(I)> 0 mol% (1)

  When the content of the structural unit derived from the monomer having a hydroxyl group of the acrylic copolymer A and the acrylic copolymer B satisfies (II)-(I)> 0 mol%, under severe environmental conditions Even if it exists, the high durability which can suppress generation | occurrence | production of foaming and peeling is obtained, and it is excellent also in suppression of light leakage.

Content of structural unit derived from monomer having hydroxyl group in acrylic copolymer A (I) and content of structural unit derived from monomer having hydroxyl group in acrylic copolymer B (II ) Is preferably 0.1 mol% or more and 10 mol% or less, more preferably 0.5 mol% or more and 5 mol% or less, and 1 mol% or more and 5 mol% or less. More preferably.
When the above (II)-(I) is 0.1 mol% or more, the durability is good, and when it is 10 mol% or less, the compatibility of the acrylic copolymer is improved.

The total amount (III) mol% of the structural unit derived from the monomer having an aromatic ring of the acrylic copolymer A and the acrylic copolymer B satisfies the relationship of the following formula (2).
(III) ≧ 3 mol% (2)
If the above (III) is less than 3 mol%, the effect of suppressing light leakage cannot be obtained sufficiently.

  The total amount (III) mol% of the structural unit derived from the monomer having an aromatic ring of the acrylic copolymer A and the acrylic copolymer B is preferably 5 mol% or more from the viewpoint of suppressing light leakage, and is 10 mol%. The above is more preferable.

The mixing ratio (A / B) of the acrylic copolymer A to the acrylic copolymer B in the pressure-sensitive adhesive composition of the present invention is preferably in the range of 90/10 to 30/70 on a mass basis. When the mixing ratio (A / B) is within the above range, the balance of the crosslinking degree of the pressure-sensitive adhesive composition due to the reaction between the acrylic copolymer A and the acrylic copolymer B and the isocyanate compound is appropriately adjusted. Therefore, the effect of improving light leakage due to stress relaxation is high, and the balance with durability can be maintained.
Especially, as said mixing ratio (A / B), the range of 90 / 10-50 / 50 is more preferable from the reason similar to the above.

In this specification, the glass transition temperature (Tg) of the acrylic copolymer is a molar average glass transition temperature determined by the following calculation. _{Tg 1,} Tg 2 of the following formulas, ... and Tg _n, the components 1, the glass transition temperature of the components 2, ... and component n respectively homopolymers, absolute temperature (K ) And calculated. m ₁ , m ₂ ,... and _mn are the mole fractions of the respective components.

[Calculation formula of glass transition temperature (Tg)]

  The “glass transition temperature (Tg) of the homopolymer” referred to herein includes L.P. E. The glass transition temperatures of the monomers described in Nielsen, translated by Nojiharu Onoki, “Mechanical properties of polymers”, pages 11 to 35, are applied.

Among the above, as a combination aspect of the acrylic copolymer A and the acrylic copolymer B in the present invention, the following (1) first aspect to (3) third aspect are preferable. That is,
(1) As a first aspect,
Acrylic copolymer A is a structural unit derived from a monomer having a hydroxyl group of 0.01 mol% or more and less than 2.4 mol%, a structural unit derived from a monomer having an aromatic ring of 3 mol% or more, A structural unit derived from an alkyl (meth) acrylate having 1 to 6 carbon atoms in the alkyl group,
Acrylic copolymer B is a structural unit derived from a monomer having a hydroxyl group of 1.2 mol% to 10.0 mol%, a structural unit derived from a monomer having an aromatic ring of 3 mol% or more, and an alkyl A constituent unit derived from an alkyl (meth) acrylate having 1 to 6 carbon atoms of the group, and a content (I) mol% of a constituent unit derived from a monomer having a hydroxyl group in the acrylic copolymer A; A mode in which the content (II) mol% of the structural unit derived from the monomer having a hydroxyl group in the acrylic copolymer B satisfies (II)-(I)> 0 mol%.
(2) As a second aspect,
The acrylic copolymer A is a structural unit derived from a monomer having a hydroxyl group of 0.1 mol% to 2.0 mol%, and a structural unit derived from a monomer having an aromatic ring of 5 mol% to 20 mol%. And a structural unit derived from n-butyl acrylate,
The acrylic copolymer B is a structural unit derived from a monomer having a hydroxyl group of 1.2 mol% to 5.0 mol%, and a structural unit derived from a monomer having an aromatic ring of 5 mol% to 20 mol%. And a structural unit derived from n-butyl acrylate,
Content (I) mol% of structural unit derived from monomer having hydroxyl group in acrylic copolymer A and content of structural unit derived from monomer having hydroxyl group in acrylic copolymer B (II) mol% satisfies (II)-(I)> 0 mol%,
The aspect whose mixing ratio (A / B) of the acrylic copolymer A with respect to the acrylic copolymer B in an adhesive composition is 90 / 10-30 / 70 on a mass basis.
(3) As a third aspect,
The acrylic copolymer A is a structural unit derived from a monomer having a hydroxyl group of 0.1 mol% to 2.0 mol%, and a structural unit derived from a monomer having an aromatic ring of 10 mol% to 20 mol%. , A structural unit derived from n-butyl acrylate, and a structural unit derived from (meth) acrylic acid,
The acrylic copolymer B is a structural unit derived from a monomer having a hydroxyl group of 1.2 mol% to 5.0 mol%, and a structural unit derived from a monomer having an aromatic ring of 10 mol% to 20 mol%. , A structural unit derived from n-butyl acrylate, and a structural unit derived from (meth) acrylic acid,
Content (I) mol% of structural unit derived from monomer having hydroxyl group in acrylic copolymer A and content of structural unit derived from monomer having hydroxyl group in acrylic copolymer B (II) The difference from mol% ((II)-(I)) satisfies 1 mol% or more and 5 mol% or less,
A mode in which the mixing ratio (A / B) of acrylic copolymer A to acrylic copolymer B in the pressure-sensitive adhesive composition is 90/10 to 50/50 on a mass basis.

  The polymerization method of the acrylic copolymer in the present invention is not particularly limited, and methods such as solution polymerization, emulsion polymerization, and suspension polymerization can be applied. Solution polymerization is preferred because the treatment process is relatively simple and can be performed in a short time.

  In solution polymerization, a predetermined organic solvent, a monomer, a polymerization initiator, and a chain transfer agent used as needed are generally charged in a polymerization tank, and stirred in a nitrogen stream or under reflux of the organic solvent. Heat the reaction for several hours. The polymerization initiator is not particularly limited, and for example, an azo compound can be used.

  The weight average molecular weight (Mw) of the acrylic copolymer can be adjusted to a desired molecular weight by adjusting the reaction temperature, time, solvent amount, and type and amount of the catalyst.

In the present specification, the weight average molecular weight (Mw) of the acrylic copolymer is a value measured by the following method. That is, it is measured according to the following (1) to (3).
(1) An acrylic copolymer solution is coated on a release sheet (release sheet) and dried at 100 ° C. for 2 minutes to obtain a film-like acrylic copolymer.
(2) The film-like acrylic copolymer obtained in (1) is dissolved in tetrahydrofuran so that the solid content is 0.2 parts by mass.
(3) Under the following conditions, the weight average molecular weight (Mw) of the (meth) acrylic copolymer is measured using gel permeation chromatography (GPC).
<Condition>
・ GPC: HLC-8220 GPC [manufactured by Tosoh Corporation]
・ Column: TSK-GEL GMHXL (4 used)
-Mobile phase solvent: Tetrahydrofuran-Standard sample: Standard polystyrene-Flow rate: 0.8 ml / min
-Column temperature: 40 ° C

-Isocyanate compounds-
The pressure-sensitive adhesive composition of the present invention contains at least one isocyanate compound. This compound is a polar compound, and the effects of the present invention (prevention of light leakage and improvement of durability) are exhibited in the case of a composition containing such a crosslinking agent.

  A preferred example of the isocyanate compound is a tolylene diisocyanate compound. As the tolylene diisocyanate compound, a tolylene diisocyanate compound derived from various isocyanates such as dimer or trimer of isocyanate or an adduct of isocyanate and trimethylolpropane polyol can be used.

  Commercially available products that are commercially available may be used as the tolylene diisocyanate compound. As examples of commercially available products, trade names “Desmodur IL1451CN”, “Desmodur ILBA”, “Desmodur HL” manufactured by Sumitomo Bayer Urethane Co., Ltd. may be used. ”,“ Sumijoule FL-2 ”,“ Sumijoule FL-3 ”, and“ SBU Isocyanate 0817 ”, trade names“ Coronate L ”,“ Coronate 2030 ”,“ Coronate 2037 ”manufactured by Nippon Polyurethane Industry Co., Ltd., and Examples include trade names “Polureen KC” and “Polurene HR” manufactured by SAPCI. Etc. can be used suitably.

The addition amount of the isocyanate compound in the pressure-sensitive adhesive composition is preferably added within a range of 1 part by mass or less with respect to 100 parts by mass of the total amount of the acrylic copolymer A and the acrylic copolymer B. When the content of the isocyanate compound is 1 part by mass or less, an appropriate cohesive force can be obtained, and a polarizing base film (especially cellulose triacetate (TAC) which is a protective sheet thereof) when exposed to high temperature and high humidity. Adhesiveness is developed, and the occurrence of peeling is suppressed.
As content in the adhesive composition of an isocyanate type compound, the range of 0.10 mass part or more and 1.00 mass part or less is preferable, The range of 0.10 mass part or more and 0.50 mass part or less is more preferable, A range of 0.10 parts by mass or more and 0.40 parts by mass or less is particularly preferable. When the content of the isocyanate compound is 0.10 parts by mass or more, a good cohesive force is exerted to suppress the shrinkage stress of the polarizing base film after the pressure-sensitive adhesive layer is adhered, and light leakage is more likely to occur. Effectively suppressed.

-Other ingredients-
The pressure-sensitive adhesive composition may further contain other cross-linking agent (for example, epoxy-based cross-linking agent) in addition to the isocyanate compound. When the pressure-sensitive adhesive composition contains an epoxy-based crosslinking agent, the cohesive force can be easily adjusted, and abnormal appearance can be suppressed even when exposed to high temperature and high humidity.

Examples of the epoxy-based crosslinking agent include 1,3-bis (N, N-glycidylaminomethyl) cyclohexane, N, N, N ′, N′-tetraglycidyl-m-xylylenediamine and the like.
The commercially available epoxy-based crosslinking agent may be a commercially available product. Examples of commercially available products include “TETRAD-X” and “TETRAD-C” (trade names) manufactured by Mitsubishi Gas Chemical Co., Ltd. It can be preferably used.

  The addition amount of the epoxy crosslinking agent in the pressure-sensitive adhesive composition is 0.001 part by mass or more and 0.1 part by mass with respect to 100 parts by mass of the total amount of the acrylic copolymer A and the acrylic copolymer B. It is preferable to add in the following range. When the content of the epoxy crosslinking agent is within the above range, it is advantageous in that the cohesive force of the pressure-sensitive adhesive layer can be adjusted and the occurrence of peeling under severe environmental conditions can be suppressed.

  The pressure-sensitive adhesive composition of the present invention may further contain a silane coupling agent. When the pressure-sensitive adhesive composition contains a silane coupling agent, the pressure-sensitive adhesive layer and the polarization base film or the liquid crystal cell even when a display device (for example, a liquid crystal display device) incorporating the polarization base film is exposed to a high temperature and high humidity environment It is hard to get peeled between. The pressure-sensitive adhesive composition of the present invention is preferable in that it exhibits good adhesion to smooth glass.

  Examples of the silane coupling agent include polymerizable unsaturated group-containing silane compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, and 3-methacryloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, and 3-mercapto. Mercapto group-containing silane compounds such as propyltriethoxysilane and 3-mercaptopropyldimethoxymethylsilane, and epoxies such as 3-glycidoxypropyltrimethoxysilane and 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane Silane compounds having a structure, such as 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, and N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane Amino group-containing silane compound, and tris - (3-trimethoxysilylpropyl) isocyanurate. These may be used alone or in combination of two or more.

  As the silane coupling agent, commercially available products may be used. Examples of commercially available products include trade names “KBM-803”, “KBM-802”, and “X-41” manufactured by Shin-Etsu Chemical Co., Ltd. Silane coupling agents having a thiol group such as “-1810”, “X-41-1805”, “X-41-1818”, “KBM-403”, “KBM-303” manufactured by Shin-Etsu Chemical Co., Ltd., “ A silane coupling agent having an epoxy group such as KBM-402, KBE-402, and KBE-403 (trade name) can be preferably used.

  The addition amount of the silane coupling agent in the pressure-sensitive adhesive composition is 0.01 parts by mass or more and 2.0 parts by mass with respect to 100 parts by mass of the total amount of the acrylic copolymer A and the acrylic copolymer B. It is preferable to add in the following range. When the content of the silane coupling agent is within the above range, the adhesiveness of the pressure-sensitive adhesive layer can be further improved.

  In addition to the above components, the pressure-sensitive adhesive composition further contains a weather resistance stabilizer such as a solvent and an ultraviolet absorber, a tackifier, a plasticizer, a softener, a dye, a pigment, an inorganic filler, and the like as necessary. Also good. When an adhesive composition contains another component, the content can be suitably selected in the range which does not impair the effect of this invention.

<Optical functional film>
The optical functional film with pressure-sensitive adhesive of the present invention comprises at least a polarizing base film and a pressure-sensitive adhesive layer formed on the polarizing base film by applying the pressure-sensitive adhesive composition of the present invention described above. ing.

  In general, for example, a polyvinyl alcohol (PVA) film is used as the polarizer. A polarizer is comprised, for example in 3 layer structure (for example, TAC / polarizer / TAC) hold | maintained between protective sheets, such as a triacetyl cellulose (TAC), and can be used as a polarizing base film.

For example, by providing the pressure-sensitive adhesive composition of the present invention described above on at least one surface of a polarizing base film having a three-layer structure of TAC / polarizer / TAC, optical functionality with pressure-sensitive adhesive is provided. A film is produced. In this case, the composition may be applied on the polarizing base film, but is preferably applied on a protective sheet (release sheet) that is peeled off during use. The application of the pressure-sensitive adhesive composition can be suitably performed by a coating method such as a dipping method, a coating method, or an ink jet method using a liquid pressure-sensitive adhesive composition. Among these, the application method is preferable.
Specifically, the pressure-sensitive adhesive composition of the present invention is coated on a protective sheet (release sheet) and dried to form a pressure-sensitive adhesive layer on the protective sheet. An optical functional film with a pressure-sensitive adhesive is produced by transferring and curing the film.

  The pressure-sensitive adhesive composition applied on the protective sheet (release sheet) is preferably dried at 70 to 120 ° C. under a drying condition of about 1 to 3 minutes using a hot air dryer or the like.

Furthermore, from the viewpoint of protecting the contact surface to the adherend, a protective sheet (release sheet) for protecting the exposed surface is provided in close contact with the exposed surface of the pressure-sensitive adhesive layer provided on the polarizing base film. It is preferable to keep it. As this protective sheet, a synthetic resin sheet such as polyester subjected to a release treatment with a release agent such as a fluororesin, paraffin wax, silicone or the like so that it can be easily separated from the adhesive layer. Preferably used. When affixing to a glass plate or the like of the display panel, the protective sheet is peeled off, and the exposed surface of the pressure-sensitive adhesive layer is adhered to the glass substrate or the like.
Moreover, you may further provide the surface protection sheet which protects the surface (exposed surface) of the side in which the adhesive layer of a polarizing base film is not provided. As the surface protective sheet, a protective film or the like that is adhesively processed on one side of a PET film is preferably used.

  The thickness of the pressure-sensitive adhesive layer is not particularly limited, but is preferably 1 μm or more and 100 μm or less, more preferably 5 μm or more and 50 μm or less, and still more preferably 15 μm or more and 30 μm or less.

  The optical functional film with pressure-sensitive adhesive of the present invention is applicable even when the size of the laminated liquid crystal cell is 19 inches wide (260 mm × 415 mm) or more. When the size of the liquid crystal cell is 19 inches wide (260 mm × 415 mm) or more, the polarization base film expands and contracts due to the influence of heat and humidity. Therefore, in the conventional optical functional film with an adhesive, since the stress is not sufficiently suppressed when exposed to high temperature and high humidity, when the light source of a large display device (for example, a liquid crystal display device) is turned on, It is not possible to suppress the occurrence of “light leakage”. On the other hand, the polarizing base film with the pressure-sensitive adhesive composition of the present invention has a structure in which the resin design of the copolymer and the type and amount of the crosslinking agent are appropriate, so that it can be exposed to high temperature and high humidity. Stress suppression is sufficient, suitable for liquid crystal cells with a size of 19 inches wide (260 mm x 415 mm) or larger, and also applicable to small display devices (liquid crystal display devices) of less than 19 inches (or less than 10 inches) Even so, the occurrence of light leakage can be suppressed by moderate stress relaxation.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist thereof. Unless otherwise specified, “part” is based on mass.

Example 1
-Production of Copolymer A-
In a reactor equipped with a thermometer, a stirrer, a nitrogen inlet tube, and a reflux condenser, 77.5 parts by mass of n-butyl acrylate (BA), 20.0 parts by mass of phenoxyethyl acrylate (PHEA), acrylic acid (AA) 2.0 parts by mass, 2-hydroxyethyl acrylate (2HEA) 0.5 part by mass and ethyl acetate (EAc) 100 parts by mass were mixed and the inside of the reactor was purged with nitrogen. Thereafter, the temperature of the mixture in the reaction vessel was raised to 70 ° C. in a nitrogen atmosphere with stirring, and then 0.02 part by mass of azobisdimethylvaleronitrile (ABVN) was mixed to carry out a polymerization reaction for 6 hours. After completion of the polymerization reaction, the reaction mixture was diluted with ethyl acetate to adjust the solid content to 15.0 parts by mass. In this way, a solution of acrylic copolymer A with BA / PHEA / AA / 2HEA = 81.6 / 14.0 / 3.8 / 0.6 (mol%) was obtained. The resulting acrylic copolymer A had a weight average molecular weight (Mw) of 1.6 million and a molecular weight distribution (Mw / Mn) of 6.

-Production of copolymer B-
In a reactor equipped with a thermometer, a stirrer, a nitrogen inlet tube, and a reflux condenser, n-butyl acrylate (BA) 76.0 parts by mass, phenoxyethyl acrylate (PHEA) 20.0 parts by mass, acrylic acid (AA) 2.0 parts by mass, 2-hydroxyethyl acrylate (2HEA) 2.0 parts by mass and ethyl acetate (EAc) 100 parts by mass were mixed and the inside of the reactor was purged with nitrogen. Thereafter, the temperature of the mixture in the reaction vessel was raised to 70 ° C. in a nitrogen atmosphere with stirring, and then 0.02 part by mass of azobisdimethylvaleronitrile (ABVN) was mixed to carry out a polymerization reaction for 6 hours. After completion of the polymerization reaction, the reaction mixture was diluted with ethyl acetate to adjust the solid content to 15.0 parts by mass. In this way, a solution of the acrylic copolymer B of BA / PHEA / AA / 2HEA = 79.9 / 14.0 / 3.8 / 2.3 (mol%) was obtained. The resulting acrylic copolymer B had a weight average molecular weight (Mw) of 1.6 million and a molecular weight distribution (Mw / Mn) of 6.

-Preparation of adhesive composition-
As acrylic copolymer A, 600.0 parts by mass (solid content: 90.0 parts by mass) of a solution of acrylic copolymer A obtained in the above production example, and as acrylic copolymer B, the above production example 66.7 parts by mass (solid content: 10.0 parts by mass) of the acrylic copolymer B obtained in the above and 0.27 parts by mass of coronate L (made by Nippon Polyurethane Industry, Tolylene Diisocyanate and Methylolpropane adduct, solid content: 0.20 parts by mass) and 0.1 part by mass of KBM-403 (manufactured by Shin-Etsu Chemical Co., Ltd., 3-glycidoxypropyltrimethoxysilane) as a silane coupling agent (SC agent) , Solid content: 100% by mass, active ingredient: 0.1 part by mass) was sufficiently stirred and mixed to obtain an adhesive composition.

(Examples 2-18, Comparative Examples 1-6)
In Example 1, as shown in Table 1 below, the composition of acrylic copolymer A and acrylic copolymer B, the weight average molecular weight, and the mixing ratio of acrylic copolymer A and acrylic copolymer B ( A pressure-sensitive adhesive composition was obtained in the same manner as in Example 1 except that the types and blending amounts of A / B) and the crosslinking agent were changed. In addition, the compounding quantity of the following table 1 is a value of solid content conversion.

-Production of optical functional film sample-
The pressure-sensitive adhesive composition was applied to the release agent-treated surface of the release film surface-treated with the silicone release agent so that the coating amount after drying was 20 g / cm ² . Next, this was dried at 100 ° C. for 60 seconds with a hot-air circulating dryer to form an adhesive layer on the release film. Subsequently, a polarizing base film (a laminated structure of TAC film / PVA film / TAC film by laminating cellulose triacetate (TAC) films on both sides of a polarizer mainly composed of polyvinyl alcohol (PVA) film; about 190 μm) The back surface of the adhesive layer and the surface of the pressure-sensitive adhesive layer were overlapped and bonded together, and pressed through a pressure nip roll. After pressure bonding, the film was cured for 10 days under an environmental condition of 23 ° C. and 65% RH, and an optical functional film having a laminate structure of release film / adhesive layer / polarizing base film was produced as an optical functional film sample.

-Evaluation-
Durability test (W / S)
A test piece of 80 mm × 140 mm (long side) prepared by cutting the optical functional film prepared in “Preparation of optical functional film sample” so that the long side becomes 0 ° with respect to the absorption axis is prepared. The release film was peeled from the test piece. By sticking the surface of the pressure-sensitive adhesive layer exposed by peeling to one surface of a 0.7 mm-thick non-alkali glass plate (Eagle XG, manufactured by Corning), the test piece is stacked on the glass plate, and a laminator is used. The laminate was pasted. Next, this laminate was subjected to autoclaving (50 ° C., 5 kg / cm ² , 20 minutes), and left for 24 hours at 23 ° C. and 50% RH. Then, after being left in a high-humidity WET environment (50 ° C., 95% RH) for 24 hours, it was immediately moved to a high-temperature condition Dry environment (70 ° C.) and left for 168 hours. After the standing time had elapsed, the state of foaming and peeling was visually observed and evaluated according to the following evaluation criteria.
<Evaluation criteria>
A: Foaming and peeling were not observed at all.
B: Foaming and peeling were hardly observed.
C: Foaming and peeling were slightly observed.
D: Foaming and peeling were observed.

Durability test (Dry)
A test piece of 80 mm × 140 mm (long side) prepared by cutting the optical functional film prepared in “Preparation of optical functional film sample” so that the long side becomes 0 ° with respect to the absorption axis is prepared. The release film was peeled from the test piece. By sticking the surface of the pressure-sensitive adhesive layer exposed by peeling to one surface of a 0.7 mm-thick non-alkali glass plate (Eagle XG, manufactured by Corning), the test piece is stacked on the glass plate, and a laminator is used. The laminate was pasted. Next, this laminate was subjected to autoclaving (50 ° C., 5 kg / cm ² , 20 minutes), and left for 24 hours at 23 ° C. and 50% RH. Thereafter, it was left in a dry environment (80 ° C.) under high temperature conditions for 168 hours. After the standing time had elapsed, the state of foaming and peeling was visually observed and evaluated according to the following evaluation criteria.
<Evaluation criteria>
A: Foaming and peeling were not observed at all.
B: Foaming and peeling were hardly observed.
C: Foaming and peeling were slightly observed.
D: Foaming and peeling were observed.

Light Leakage Test 260 mm × 460 mm (long side) test in which the optical functional film prepared in “Preparation of optical functional film sample” is cut so that the long sides are 0 ° and 90 ° with respect to the absorption axis. One piece was prepared for each, and the release film was peeled from the test piece. The surface of the pressure-sensitive adhesive layer exposed by peeling was attached to both surfaces of a VA liquid crystal panel using a laminator so that the polarization axes of the two optical functional film samples were orthogonal to each other, thereby preparing a test piece. . The obtained test piece was autoclaved (50 ° C., 5 kg / cm ² (490 kPa), 20 minutes) and then allowed to stand for 24 hours at 23 ° C. and 50% RH. Then, it was left to stand for 168 hours at 70 ° C. Using a uniform light source under conditions of 23 ° C. and 50% RH, the state of light leakage was visually observed and evaluated according to the following evaluation criteria.
<Evaluation criteria>
A: Almost no light leakage was observed.
B: Light leakage was slightly observed.
C: Remarkable light leakage was observed.

Each monomer and crosslinking agent in Table 1 will be described below.
BA: n-butyl acrylate AA: acrylic acid PHEA: phenoxyethyl acrylate BzA: benzyl acrylate
(Used in place of PHEA in Example 15)
2HEA: 2-hydroxyethyl acrylate 4HBA: 4-hydroxybutyl acrylate
(Used instead of 2HEA in Example 14)
Coronate L: Adduct of tolylene diisocyanate and trimethylolpropane
Coronate 2037: isocyanurate of tolylene diisocyanate
(Used instead of Coronate L in Example 11)

  As shown in Table 1, in the examples, regardless of “W / S” and “Dry”, the occurrence of foaming and peeling is suppressed, good durability is obtained, and “light leakage” is obtained. It can be seen that is also suppressed.

Claims (9)

An acrylic copolymer A comprising a structural unit derived from a monomer having a hydroxyl group, a structural unit derived from a monomer having an aromatic ring, and a structural unit derived from an alkyl (meth) acrylate;
An acrylic copolymer B comprising a structural unit derived from a monomer having a hydroxyl group, a structural unit derived from a monomer having an aromatic ring, and a structural unit derived from an alkyl (meth) acrylate;
An isocyanate compound,
The mixing ratio (A / B) of the acrylic copolymer A to the acrylic copolymer B is 90/10 to 30/70 on a mass basis,
The content (I) of the structural unit derived from the monomer having a hydroxyl group in the acrylic copolymer A is 0.01 mol% or more and less than 2.4 mol%,
The content (II) of the structural unit derived from the monomer having a hydroxyl group in the acrylic copolymer B is 1.2 mol% or more and 10.0 mol% or less,
Content (I) [mol%] of the structural unit derived from the monomer having a hydroxyl group in the acrylic copolymer A and the composition derived from the monomer having a hydroxyl group in the acrylic copolymer B The unit content (II) [mol%] satisfies the relationship represented by the following formula (1),
The total amount (III) [mol%] of the structural units derived from the monomer having an aromatic ring in the acrylic copolymer A and the acrylic copolymer B is represented by the following formula (2). A pressure-sensitive adhesive composition used for attaching an optical functional film to be filled .
(II)-(I)> 0 mol% (1)
(III) ≧ 3 mol% (2) Content (I) of the structural unit derived from the monomer having a hydroxyl group in the acrylic copolymer A and Content of the structural unit derived from the monomer having a hydroxyl group in the acrylic copolymer B The pressure-sensitive adhesive composition according to claim 1, wherein the difference from (II) ((II)-(I)) is 0.1 mol% or more and 10 mol% or less. The pressure-sensitive adhesive composition according to claim 1 or 2, wherein the acrylic copolymer A and the acrylic copolymer B have a weight average molecular weight of 500,000 or more. The mixing ratio of the acrylic copolymer A to the acrylic copolymer B (A / B) is, in any one of claims 1 to 3 is 90 / 10-50 / 50 by weight The pressure-sensitive adhesive composition described. The addition amount of the isocyanate compound is 0.1 part by mass to 1.0 part by mass with respect to 100 parts by mass of the total amount of the acrylic copolymer A and the acrylic copolymer B. The pressure-sensitive adhesive composition according to claim 4 . The structural unit derived from the alkyl (meth) acrylate of the acrylic copolymer A and the acrylic copolymer B is a structural unit derived from an alkyl (meth) acrylate having 1 to 6 carbon atoms. The pressure-sensitive adhesive composition according to claim 5 . The structural unit derived from the monomer having a hydroxyl group of the acrylic copolymer A and the acrylic copolymer B is a structural unit derived from a (meth) acrylic monomer. 6. The pressure-sensitive adhesive composition according to any one of 6 above. The structural unit derived from the monomer having an aromatic ring of the acrylic copolymer A and the acrylic copolymer B is a structural unit derived from a (meth) acrylic monomer. Item 8. The pressure-sensitive adhesive composition according to any one of items 7 . A polarizing base film;
An adhesive layer provided on the polarizing base film and derived from the adhesive composition according to any one of claims 1 to 8 ,
Optical functional film with