JP2018095844A - Adhesive composition for optical film, adhesive layer, optical member and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide means for achieving both of durability and reworkability in severe environments (high temperature, high humidity and heat shock) in an adhesive composition to be used in an image display device and an optical member, as well as for sufficiently suppressing leakage of light.SOLUTION: An adhesive composition for an optical film according to the present invention includes a (meth)acrylate copolymer (A) and an isocyanate compound (B). The (meth)acrylate copolymer (A) includes (a1) a structural unit derived from an alkyl (meth)acrylate monomer, (a2) a structural unit derived from a (meth)acrylate monomer having a hydroxyl group, and (a3) a structural unit derived from a (meth)acrylate monomer having an aromatic ring. The isocyanate compound (B) has a number average molecular weight of 900 or more and 10,000 or less.SELECTED DRAWING: None

Description

  The present invention relates to an optical film pressure-sensitive adhesive composition. Moreover, this invention relates also to the adhesive layer formed from the said adhesive composition for optical films, the optical member using the said adhesive layer, and the image display apparatus using the said optical member.

  In addition to the indispensable polarizing film (polarizing plate), optical members such as various optical films are attached to liquid crystal panels such as liquid crystal display devices, which are a type of image display device, in order to improve display quality. Has been. When an optical member such as an optical film is attached to a liquid crystal panel, or when two or more optical films of the same kind or different kinds are attached to each other, an adhesive is usually used.

  Necessary properties of the adhesive include durability in the adhesive state where the adhesive does not cause problems such as peeling or floating due to the adhesive against the durability test by heating and humidification normally performed as an environmental promotion test. Is required. Particularly in recent years, optical films used for in-vehicle panels are required not to cause defects such as foaming or peeling due to adhesives in durability tests at higher temperatures and higher humidity than in the past. ing.

  Also, when the optical film is bonded to the liquid crystal panel using an adhesive, the optical film will be peeled off from the liquid crystal panel if the bonding position is incorrect or if a foreign object is caught in the bonding surface. Then, it is necessary to perform pasting again. In particular, in recent years, in addition to the manufacturing process of conventional liquid crystal display devices, the use of liquid crystal display devices such as thin liquid crystal panels using chemically etched glass has increased, and optical films have become thin and brittle. In contrast to such thin liquid crystal display devices and thin optical films, using conventional adhesives that aim only for durability would cause the thin liquid crystal display devices and thin optical films to break or break. A problem came out. For this reason, in such a peeling process, there is a demand for a property of an adhesive called re-peelability (also referred to as “reworkability”) that can easily peel off an optical film without leaving adhesive residue from a liquid crystal display device or the like. ing. Furthermore, in addition to the above-mentioned “durability” and “reworkability”, a performance capable of preventing light leakage when used in a liquid crystal panel is also required. This light leakage results in non-uniform residual stress in the polarizing plate, particularly in a high-temperature and high-humidity environment, when the stress accompanying the dimensional change such as contraction or expansion of the polarizing plate cannot be relaxed by the adhesive layer. .

  Further, in the thin liquid crystal panel, there is a problem that the optical film warps due to expansion or contraction due to heating, humidification, etc., and the display quality is deteriorated by contacting the frame. . However, if the stress relaxation property of the pressure-sensitive adhesive is increased in order to relieve the expansion or contraction due to heating and humidification of the optical film, the workability and the dent are deteriorated and the defect rate in the process is deteriorated.

  In addition, for adhesive optical films used for highly versatile products such as those for television (TV), there is a demand for further reduction in production cost, and it is necessary to increase the line speed of adhesive production. Yes. In this way, with good workability, it is possible to suppress warpage and dents at the same time, have high durability and reworkability, and have excellent handling properties in terms of manufacturing process. There is a demand for pressure-sensitive adhesives for optical films from which films can be obtained.

  Therefore, an acrylic copolymer (A) is used as an adhesive that can reduce floating and peeling from an adherend even after being exposed to a high temperature environment or a high temperature and high humidity environment, and can produce an adhesive layer with good light leakage evaluation. And a compound (B) having an isocyanate group, wherein the compound (B) having the isocyanate group has 2 functional groups capable of reacting with the bifunctional isocyanate compound (b1) and the isocyanate group. There has been proposed a pressure-sensitive adhesive obtained by reacting a compound (b2) having a number average molecular weight of 500 or more and 5000 or less (Patent Documents 1 and 2).

JP 2012-171963 A JP 2014-205843 A

  However, according to the study by the present inventors, durability (high temperature, high humidity, heat shock) in a harsh environment (high temperature) even with the pressure-sensitive adhesive composition described in Patent Documents 1 and 2 above. It has been found that there are cases where the foaming resistance at the surface of the substrate, the float and peeling from the adherend under high temperature and high humidity) and the reworkability (workability) are not sufficient, or light leakage may occur. Furthermore, it has been found that, in addition to the case where the durability and reworkability are not sufficient, the occurrence of both warpage and dents may not be suppressed.

  Therefore, the present invention has been made in view of the above circumstances, and in the pressure-sensitive adhesive composition for optical films, durability (high-temperature, high-humidity, heat shock) in a harsh environment (high-temperature foaming resistance and It is an object of the present invention to provide a means capable of improving reworkability (workability) and also sufficiently suppressing light leakage while floating and peeling from an adherend under high temperature and high humidity. Another object of the present invention is to provide means capable of improving the durability and reworkability, sufficiently suppressing light leakage, and further suppressing both warpage and dents.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by a pressure-sensitive adhesive composition having a specific component, and have completed the present invention.

  That is, the present invention provides an optical film pressure-sensitive adhesive composition of the present invention comprising a (meth) acrylate copolymer (A) and an isocyanate compound (B), wherein the (meth) acrylate copolymer (A ) Is derived from (a1) a structural unit derived from an alkyl (meth) acrylate monomer, (a2) a structural unit derived from a (meth) acrylate monomer having a hydroxyl group, and (a3) derived from a (meth) acrylate monomer having an aromatic ring. The isocyanate compound (B) is a pressure-sensitive adhesive composition for optical films having a number average molecular weight (Mn) of 900 or more and 10,000 or less.

  According to one aspect of the present invention, it is possible to achieve both durability and reworkability (workability) in a harsh environment (high temperature, high humidity, heat shock) and sufficiently suppress light leakage. An adhesive composition for optical films is provided. Moreover, according to the other form of this invention, while being able to make the said durability and rework property compatible, it can fully suppress light leakage, and also can suppress curvature and a dent, and can suppress a curvature and a dent. Things are provided.

  Hereinafter, modes for carrying out the present invention will be described.

{Adhesive composition for optical film}
The pressure-sensitive adhesive composition for an optical film of the present invention contains a (meth) acrylate copolymer (A) and an isocyanate compound (B), and the (meth) acrylate copolymer (A) is (a1) A structural unit derived from an alkyl (meth) acrylate monomer, (a2) a structural unit derived from a (meth) acrylate monomer having a hydroxyl group, and (a3) a structural unit derived from a (meth) acrylate monomer having an aromatic ring. The isocyanate compound (B) has a number average molecular weight (Mn) of 900 or more and 10,000 or less.

  According to the pressure-sensitive adhesive composition for an optical film according to an embodiment of the present invention having such a configuration, the optical film can be easily peeled off from the liquid crystal panel with durability in a harsh environment (high temperature, high humidity, heat shock). In addition to being able to achieve both reworkability and light leakage, it is possible to sufficiently suppress light leakage. In addition, according to the pressure-sensitive adhesive composition for an optical film according to another embodiment of the present invention, the durability and the reworkability can be achieved at the same time, light leakage can be sufficiently suppressed, and warpage and dents can be further suppressed. Can be sufficiently suppressed.

  Generally, in order to provide durability of an optical film or an optical member having an adhesive layer, the adhesive composition of the adhesive layer is devised so as to increase the adhesive strength to a certain range. For example, in Patent Documents 1 and 2 described above, it is suggested that “the adhesive strength is 3N / 25 mm or more and 10 N / 25 mm or less, there is no problem in practical use”. However, the higher the adhesive strength is, the more difficult it is to peel off the optical film due to the recent thinning of the optical film, so that the reworkability cannot be satisfied. That is, it is difficult to achieve durability and reworkability at the same time. Patent Documents 1 and 2 evaluate the heat resistance after leaving for 500 hours at 85 ° C. and the heat and moisture resistance after leaving for 500 hours at 60 ° C. and a relative humidity of 95% RH. However, according to the study by the present inventors, in a harsh environment such as the present invention, that is, high temperature (for example, 105 ° C. for 500 hours), high humidity (for example, 60 ° C., relative humidity 95% RH for 500 hours) In an environment such as heat shock (for example, each of them is left for 30 minutes in an environment of 85 ° C. and −40 ° C. and repeatedly treated for 300 hours), the pressure-sensitive adhesive composition disclosed in Patent Documents 1 and 2 is used. It was found that the durability was not sufficient. In addition, it was found that reworkability was not sufficient. Moreover, it turned out that the said durability and rework property may not be enough, and also generation | occurrence | production of curvature and a dent cannot be suppressed. On the other hand, the pressure-sensitive adhesive composition for an optical film of the present invention has succeeded in achieving both durability and reworkability in a harsh environment by having a specific component. In addition, it has succeeded in further suppressing warpage and dents while achieving both the above durability and reworkability.

  Regarding “light leakage”, Patent Documents 1 and 2 focus on reducing stress concentration in the pressure-sensitive adhesive layer in order to suppress light leakage from the end due to dimensional changes such as contraction or expansion of the polarizing plate. It seems to be doing. That is, the pressure-sensitive adhesive composition described in Patent Documents 1 and 2 suppresses the contraction or expansion of the polarizing plate when the pressure-sensitive adhesive layer using the same has stress relaxation properties. This is to suppress leakage. However, as a result of research by the present inventors, the pressure-sensitive adhesive compositions described in Patent Documents 1 and 2 can suppress the occurrence of light leakage after leaving for 500 hours at 85 ° C. as in the present invention. It was found that light leakage occurred slightly over the entire polarizing plate under a harsh environment, that is, an environment such as a high temperature (for example, at 105 ° C. for 500 hours). In addition, the pressure-sensitive adhesive layer is soft because it has stress relaxation properties. “Glue stains” that contaminate the optical film occur.

  On the other hand, the pressure-sensitive adhesive composition for optical films of the present invention sufficiently suppresses light leakage even under an environment such as a high temperature (for example, at 105 ° C. for 500 hours) by having specific components. Succeeded in doing. The reason for this is not clear, but the specific birefringence of the resulting pressure-sensitive adhesive layer is constant by using a specific structural component of the present invention, in particular, (a3) a structural unit derived from a (meth) acrylate monomer having an aromatic ring. It is considered that light leakage could be suppressed. Further, there is no problem as described above in the processing step.

  Hereinafter, each component which comprises the adhesive composition for optical films of this invention is demonstrated in order.

  In the present specification, “(meth) acrylate” is a general term for acrylate and methacrylate. Similarly, a compound containing (meth) such as (meth) acrylic acid is a general term for a compound having “meta” in the name and a compound not having “meta”. Further, “(meth) acrylate copolymer (A)” is also referred to as “(meth) acrylic acid ester copolymer (A)” or “copolymer (A)”.

<(Meth) acrylate copolymer (A)>
The pressure-sensitive adhesive composition for an optical film of the present invention essentially contains a (meth) acrylate copolymer (A). When the (meth) acrylate copolymer (A) reacts with the later-described isocyanate compound (B) and further includes the later-described crosslinking agent (C), it also reacts with the crosslinking agent (C) to form a crosslinked structure. By forming, adhesiveness (tackiness) is exhibited. In the present invention, based on the physical properties such as the molecular weight of the copolymer (A), the high molecular weight first embodiment and the second embodiment having a low molecular weight and a composition having a predetermined viscosity and the like are described separately. To do.

(First embodiment)
The weight average molecular weight (Mw) of the (meth) acrylate copolymer (A) according to the first embodiment of the present invention is not particularly limited, but is preferably 1 million or more and 2.5 million or less, and 1.3 million or more and 2.2 million. Or less, more preferably 1.5 to 2 million. This is because the high molecular weight component (A) in the above range is cross-linked with an isocyanate compound (B) with a specific chain length to loosen the network to form a loose network structure, thereby alleviating the shrinkage of the polarizing plate at high temperatures. It is because it becomes difficult to peel off. Thereby, it is preferable from the viewpoint that the durability under a severe environment can be greatly improved such that peeling does not occur even under a severe environment (high temperature, high humidity, heat shock). Moreover, it is preferable also from a viewpoint of the improvement of the productivity at the time of coating. The weight average molecular weight (Mw) of the copolymer (A) according to the first embodiment of the present invention appropriately adjusts the polymerization initiator used in the polymerization reaction described later, reaction conditions such as reaction temperature and reaction time, and the like. Therefore, it can be easily controlled by those skilled in the art. In addition, in this specification, a weight average molecular weight can be measured by the method shown in an Example.

  In addition, the number average molecular weight (Mn) of the (meth) acrylate copolymer (A) according to the first embodiment of the present invention is not particularly limited, but it is durable in harsh environments (high temperature, high humidity, heat shock). From the viewpoint that it can improve the productivity and productivity at the time of coating, and can sufficiently suppress light leakage, it is preferably 300,000 to 1.9 million, more preferably 400,000 to 1.7 million, It is especially preferable that it is 500,000 or more and 1.6 million or less. In addition, the number average molecular weight (Mn) of the copolymer (A) according to the first embodiment of the present invention is determined appropriately depending on the polymerization initiator used in the polymerization reaction described later, reaction conditions such as reaction temperature and reaction time, and the like. Those skilled in the art can easily control the adjustment. In the present specification, the number average molecular weight (Mn) can be measured by the method shown in Examples.

  Further, the dispersity (Mw / Mn) of the (meth) acrylate copolymer (A) according to the first embodiment of the present invention is not particularly limited, but in a harsh environment (high temperature, high humidity, heat shock). From the viewpoint of improving durability, it is preferably 1.1 or more and 5.0 or less, more preferably 1.2 or more and 4.0 or less, and particularly preferably 1.3 or more and 3.0 or less. preferable. The dispersity (Mw / Mn) can be measured by the method shown in the examples.

  In 1st Embodiment of this invention, the adhesive composition for optical films can contain a solvent further as needed other than essential components, such as the said copolymer (A) and the isocyanate compound (B) mentioned later. . In such a case, the solid content in the optical film pressure-sensitive adhesive composition according to the first embodiment of the present invention is not particularly limited, but from the viewpoint of improving productivity during coating, the pressure-sensitive adhesive for optical films. Preferably they are 10 mass% or more and 50 mass% or less with respect to 100 mass% of total amounts of a composition, More preferably, they are 12 mass% or more and 30 mass% or less. On the other hand, the content of the solvent in the optical film pressure-sensitive adhesive composition in the first embodiment of the present invention is not particularly limited, but from the viewpoint of improving productivity during coating, the pressure-sensitive adhesive composition for optical films. Preferably, they are 50 mass% or more and 90 mass% or less with respect to 100 mass% of total quantity, More preferably, they are 70 mass% or more and 88 mass% or less.

(Second Embodiment)
Although the weight average molecular weight (Mw) by the gel permeation chromatography of the (meth) acrylate copolymer (A) according to the second embodiment of the present invention is not particularly limited, it is preferably 300,000 or more and less than 1,000,000. And more preferably 400,000 or more and 950,000 or less, and further preferably 500,000 or more and 900,000 or less. When the component (A) has a low molecular weight within the above range, the molecular weight of the component (A) is small by adjusting the solid content and solvent amount of the component (A), and further the viscosity of the pressure-sensitive adhesive composition. A network is formed by crosslinking with an isocyanate compound (B) having a specific chain length to form a network (to form a network structure). Thus, conventionally, when the low molecular weight component (A) in the above range is used, it is possible to obtain a special effect that it becomes difficult to peel off what was peeled off immediately when the contraction of the polarizing plate is increased at high temperature. It is what I found. Further, the effect of suppressing the occurrence of warpage due to the effect of the low molecular weight of the component (A) is excellent, and the effect of suppressing the occurrence of dents is also excellent due to the network structure although it has a low molecular weight. Moreover, it is excellent also in the productivity improvement effect at the time of coating by the effect of low molecular weight reduction of a component (A), viscosity adjustment, etc. Thus, it is preferable from the viewpoint that the balance between warpage and dent occurrence suppression effect is particularly excellent in addition to the durability improvement effect (peeling suppression effect) and the productivity improvement effect at the time of coating. The weight average molecular weight (Mw) of the copolymer (A) according to the second embodiment of the present invention appropriately adjusts the polymerization initiator used in the polymerization reaction described later, reaction conditions such as reaction temperature and reaction time, and the like. Therefore, it can be easily controlled by those skilled in the art.

  In addition, the number average molecular weight (Mn) of the (meth) acrylate copolymer (A) according to the second embodiment of the present invention is not particularly limited, but it can greatly improve durability and productivity during coating. In addition, from the viewpoint that the balance between warpage and dent occurrence suppression effect is particularly excellent, it is preferably 50,000 or more and 400,000 or less, more preferably 70,000 or more and 300,000 or less, and 80,000 or more and 200,000 or less. It is particularly preferred that In addition, the number average molecular weight (Mn) of the copolymer (A) according to the second embodiment of the present invention is determined appropriately depending on the polymerization initiator used in the polymerization reaction described later, reaction conditions such as reaction temperature and reaction time, and the like. Those skilled in the art can easily control the adjustment.

  Further, the dispersity (Mw / Mn) of the (meth) acrylate copolymer (A) according to the second embodiment of the present invention is not particularly limited, but both durability and reworkability are compatible, and further during coating. From the viewpoint that the balance between the warpage and the effect of suppressing the occurrence of dents is particularly excellent, in addition to the significant improvement effect of the productivity, it is preferably 2.0 or more and 20 or less, and preferably 2.5 or more and 15 or less. More preferably, it is 3.0 or more and 10 or less. The dispersity (Mw / Mn) can be measured by the method shown in the examples.

  In the second embodiment of the present invention, the pressure-sensitive adhesive composition for an optical film significantly improves productivity during coating in addition to the above-mentioned copolymer (A) and components such as an isocyanate compound (B) described later. From the viewpoint of effects and the like, it is preferable to include a solvent. The solid content including the copolymer (A) in the optical film pressure-sensitive adhesive composition according to the second embodiment of the present invention is not particularly limited, but is excellent in the productivity improvement effect during coating. From the viewpoint, it is preferably 20% by mass or more, more preferably 20% by mass or more and 70% by mass or less, and more preferably 22% by mass or more and 50% by mass with respect to 100% by mass of the total amount of the pressure-sensitive adhesive composition for optical films. % Or less, more preferably 23% by mass or more and 30% by mass or less. In particular, by controlling within the above range, the solid content at the time of coating is high, the coating speed can be secured at a higher level than ever, and the handling property is excellent in terms of manufacturing process, and the adhesive type optics with good quality. The adhesive composition for optical films which can obtain a film can be provided. On the other hand, the content of the solvent in the optical film pressure-sensitive adhesive composition in the second embodiment of the present invention is not particularly limited, but from the viewpoint of excellent productivity improvement effect during coating, for optical films. It is preferably 80% by mass or less, more preferably 30% by mass to 80% by mass, and more preferably 50% by mass to 78% by mass with respect to 100% by mass of the total amount of the pressure-sensitive adhesive composition. More preferably, it is 70 mass% or more and 77 mass% or less especially. The solid content in the optical film pressure-sensitive adhesive composition of the present invention can be easily controlled by those skilled in the art by appropriately adjusting the amount of each component constituting the optical film pressure-sensitive adhesive composition. The solid content can be measured by removing (solid-liquid separation) the non-solid component from the optical film pressure-sensitive adhesive composition. The content of the solvent in the optical film pressure-sensitive adhesive composition of the present invention can also be easily controlled by those skilled in the art by appropriately adjusting the amounts of the respective components constituting the optical film pressure-sensitive adhesive composition. The content of the solvent can be measured by volatilizing and drying the solvent from the optical film pressure-sensitive adhesive composition.

(solvent)
As explained in the first and second embodiments, the pressure-sensitive adhesive composition for optical films of the present invention may contain a solvent as necessary. Such a solvent is not particularly limited, but esters such as ethyl acetate and n-butyl acetate; aromatic hydrocarbons such as toluene and benzene; aliphatic hydrocarbons such as n-hexane and n-heptane; cyclohexane, Examples thereof include organic solvents such as alicyclic hydrocarbons such as methylcyclohexane; ketones such as methyl ethyl ketone and methyl isobutyl ketone. These solvents may be used alone or in combination of two or more.

  Furthermore, in the pressure-sensitive adhesive composition for optical films according to the second embodiment of the present invention, the viscosity of the B-type viscometer at 23 ° C. at 20 rpm is not particularly limited, but the effect of greatly improving the productivity at the time of coating. From the viewpoint of being excellent, it is preferably 200 mPa · s or more and 5000 mPa · s or less, more preferably 400 mPa · s or more and 4500 mPa · s or less, further preferably 500 mPa · s or more and 4000 mPa · s or less, It is particularly preferably 500 mPa · s or more and 3500 mPa · s or less. The viscosity of the pressure-sensitive adhesive composition for optical films according to the second embodiment of the present invention at 23 ° C. with a B-type viscometer at 20 rpm is the molecular weight of the (meth) acrylate copolymer (A), the solid content, and the thickener. Those skilled in the art can easily control the viscosity by appropriately adjusting the addition of an additive capable of adjusting the viscosity. In the present specification, the viscosity of the optical film pressure-sensitive adhesive composition at 23 ° C. with a B-type viscometer at 20 rpm can be measured by the method shown in the Examples.

  Hereinafter, each component common to the above-described first and second embodiments will be described.

In the present invention, the (meth) acrylate copolymer (A) includes (a1) a structural unit derived from an alkyl (meth) acrylate monomer, (a2) a structural unit derived from a (meth) acrylate monomer having a hydroxyl group, and (a3). And a structural unit derived from a (meth) acrylate monomer having an aromatic ring. In the present specification, “the copolymer X includes a structural unit derived from the monomer Y _{1 and} a structural unit derived from the monomer Y ₂ ” is used when the copolymer X is obtained by copolymerization. as the raw material monomer is meant to include a monomer Y ₁ and monomer Y _2. Therefore, the (meth) acrylate copolymer (A) according to the present invention is, in other words, (a1) an alkyl (meth) acrylate monomer, (a2) a (meth) acrylate monomer having a hydroxyl group, and (a3) an aromatic It is a copolymer formed by copolymerizing a (meth) acrylate monomer having a ring.

  Hereinafter, the structural unit derived from each monomer which comprises the copolymer (A) based on this invention is demonstrated in order.

[(A1) Structural unit derived from alkyl (meth) acrylate monomer]
The copolymer (A) according to the present invention includes (a1) a structural unit derived from an alkyl (meth) acrylate monomer (hereinafter, also simply referred to as “component (a1)”). By including such a component (a1) as a structural unit of the (meth) acrylate copolymer (A) according to the present invention, it is considered that the component (a1) has the significance of ensuring adhesiveness and basic characteristics.

  In the present invention, the structure of the alkyl (meth) acrylate monomer is not particularly limited as long as the alkyl group is introduced into the ester site of (meth) acrylate.

  The number of carbon atoms of the alkyl group is not particularly limited, but is preferably 1 or more and 20 or less, more preferably 1 or more and 12 or less, and more preferably 1 or more and 10 or less from the viewpoints of versatility, price, and handling. Is more preferably 1 or more and 8 or less, and particularly preferably 1 or more and 6 or less. The alkyl group may be linear, branched or cyclic, but is preferably linear or branched from the viewpoint of lowering the glass transition temperature. In addition, when an alkyl group is cyclic | annular, carbon number is 3 or more.

  The alkyl group is not particularly limited, but is methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, sec-butyl group, t-butyl group, isobutyl group, n-pentyl group, isopentyl group, n -Hexyl group, 2-hexyl group, 3-hexyl group, cyclohexyl group, 1-methylcyclohexyl group, n-heptyl group, 2-heptyl group, 3-heptyl group, isoheptyl group, t-heptyl group, n-octyl group , Isooctyl group, t-octyl group, 2-ethylhexyl group, nonyl group, isononyl group, decyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, or octadecyl group. In particular, a methyl group, an n-butyl group, an n-hexyl group, a 2-ethylhexyl group, a nonyl group, and an isononyl group are preferable from the viewpoint of ensuring adhesiveness and basic characteristics.

  Therefore, specific examples of the alkyl (meth) acrylate monomer include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, and isobutyl (meth). Acrylate, t-butyl (meth) acrylate, n-pentyl (meth) acrylate, isopentyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, Nonyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, etc. are mentioned. Of these, methyl (meth) acrylate and n-butyl (meth) acrylate are preferred from the viewpoint of improving heat durability and adhesive strength (particularly reworkability). In addition, these can be used individually or in mixture of 2 or more types.

  The content of the component (a1) in the copolymer (A) according to the present invention (the blending amount of the alkyl (meth) acrylate monomer as a raw material monomer) is not particularly limited, but the content of other raw material monomers described later From the viewpoint of a good balance of the resin, improvement in durability, and the like, the total amount of the structural units constituting the (meth) acrylate copolymer (A) is 100% by mass or more and 99% by mass or less. It is preferably 60% by mass or more and 97% by mass or less, and particularly preferably 70% by mass or more and 95% by mass or less. In the present specification, “the total amount of structural units constituting the (meth) acrylate copolymer (A) is 100% by mass” means that when the (meth) acrylate copolymer (A) is obtained by copolymerization, It means that the total amount of all raw material monomers used is 100% by mass.

[(A2) a structural unit derived from a (meth) acrylate monomer having a hydroxyl group]
The copolymer (A) according to the present invention includes (a2) a structural unit derived from a (meth) acrylate monomer having a hydroxyl group (hereinafter also simply referred to as “component (a2)”). Since such a component (a2) is rich in reactivity with the intermolecular crosslinking agent, it is included as a constituent unit of the copolymer (A) according to the present invention, so that the cohesiveness and heat resistance of the pressure-sensitive adhesive layer described later are included. It is thought that it has the meaning which improves sex. Further, as a result of studies by the present inventors, the component (a2) part of the copolymer (A) reacts with the isocyanate compound (B) according to the present invention, and the crosslinking density of the pressure-sensitive adhesive layer to be described later increases and the pressure-sensitive adhesive layer. The amount of deformation of the pressure-sensitive adhesive layer at the time of re-peeling becomes small (the length of glueing is small), which reduces the adhesive strength, provides desirable reworkability, and can also prevent peeling in durability. I understood. Furthermore, it was also found that the occurrence of warpage and dents can be suppressed by changing the weight average molecular weight, viscosity, etc. without changing the structural unit of the copolymer (A) and the amount of its components.

  In the present invention, the structure of the (meth) acrylate monomer having a hydroxyl group is not particularly limited as long as the hydroxyl group is introduced into a part of the (meth) acrylate monomer.

  Specific examples of the (meth) acrylate monomer having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 1,6-hexanediol mono (meth) acrylate, pentaerythritol tri (meth) ) Acrylate, dipentaerythritol penta (meth) acrylate, neopentyl glycol mono (meth) acrylate, trimethylolpropane di (meth) acrylate, trimethylolethanedi (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2- Hydroxybutyl (meth) acrylate, 2-hydroxy-3-phenyloxypropyl (meth) acrylate, 4-hydroxycyclohexyl (meth) acrylate, hydroxymethyl (meth) acrylate Examples include amide, hydroxyethyl (meth) acrylamide, cyclohexanedimethanol monoacrylate, and addition of glycidyl group-containing compounds such as alkyl glycidyl ether, allyl glycidyl ether, glycidyl (meth) acrylate, and (meth) acrylic acid. Examples include compounds obtained by the reaction. Among these, 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, from the viewpoint of efficiently functioning as a crosslinking point when using the isocyanate compound (B) and the crosslinking agent (C) described later, 2-hydroxyethyl (meth) acrylamide and cyclohexanedimethanol monoacrylate are preferred, and 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate are more preferred. In addition, these can be used individually or in mixture of 2 or more types.

  The content of component (a2) in the copolymer (A) according to the present invention (the amount of the (meth) acrylate monomer having a hydroxyl group as a raw material monomer) is not particularly limited, but the (meth) acrylate copolymer It is preferable that it is 0.01 mass% or more and 10 mass% or less with respect to 100 mass% of the whole quantity of the structural unit which comprises a coalescence (A). When the content is 0.01% by mass or more, the number of crosslinking reaction points does not decrease too much, and it is possible to contribute to the durability effect by securing a suitable crosslinking reaction point. On the other hand, if the amount is 10% by mass or less, the proportion of the polar monomer to be blended does not become excessively large, and an adhesive layer having a desired polarity can be formed. Can contribute.

  The content of the component (a2) is preferably 0.05% by mass or more and 5% by mass or less, more preferably 0.1% by mass or more and 4% by mass or less, from the viewpoint of further exerting the effects of the present invention. And particularly preferably more than 0.5% by mass and 3% by mass or less.

[(A3) a structural unit derived from a (meth) acrylate monomer having an aromatic ring]
The copolymer (A) according to the present invention includes (a3) a structural unit derived from a (meth) acrylate monomer having an aromatic ring (hereinafter also simply referred to as “component (a3)”). Such a component (a3) can mainly contribute to suppression of light leakage in the pressure-sensitive adhesive composition for optical films.

  In the present invention, the structure of the (meth) acrylate monomer having an aromatic ring is not particularly limited, and has any structure as long as the structure includes an aromatic ring (aromatic ring) and a (meth) acryloyl group. It may be a thing. Here, although there is no restriction | limiting in particular as an aromatic ring, A benzene ring, a naphthalene ring, a biphenyl ring etc. are mentioned.

  Specific examples of the (meth) acrylate monomer having an aromatic ring include benzyl (meth) acrylate, phenyl (meth) acrylate, o-phenylphenol (meth) acrylate phenoxy (meth) acrylate, and pt-butylphenyl (meth). Acrylate, phenoxyethyl (meth) acrylate, phenoxypropyl (meth) acrylate, phenoxydiethylene glycol (meth) acrylate, ethylene oxide modified nonylphenol (meth) acrylate, ethylene oxide modified cresol (meth) acrylate, phenol ethylene oxide modified (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, methoxybenzyl (meth) acrylate, chlorobenzyl (meth) acrylate , Having a benzene ring such as cresyl (meth) acrylate, polystyryl (meth) acrylate; hydroxyethylated β-naphthol acrylate, 2-naphthoethyl (meth) acrylate, 2-naphthoxyethyl acrylate, 2- (4-methoxy- Examples thereof include those having a naphthalene ring such as 1-naphthoxy) ethyl (meth) acrylate; those having a biphenyl ring such as biphenyl (meth) acrylate. Of these, benzyl (meth) acrylate and phenoxyethyl (meth) acrylate are preferred from the viewpoint of suppressing light leakage and ensuring durability. In addition, these may contain only 1 type and may contain it in combination of 2 or more type.

  The content of the component (a3) in the copolymer (A) according to the present invention (the amount of the (meth) acrylate monomer having an aromatic ring as a raw material monomer) is not particularly limited, but light leakage can be sufficiently suppressed. And from a viewpoint of ensuring durability, it is preferable that it is 0.99 mass% or more and 30 mass% or less with respect to 100 mass% of the whole quantity of the structural unit which comprises the said (meth) acrylate copolymer (A). More preferably, they are 10 mass% or more and 30 mass% or less, More preferably, they are 10 mass% or more and 25 mass% or less, Especially preferably, they are 11 mass% or more and 20 mass% or less.

[(A4) Structural units derived from monomers other than (a1) to (a3)]
The copolymer (A) according to the present invention is derived from monomers other than the above (a1) to (a3), which can be copolymerized with the above-described components (a1), (a2), and (a3) as optional components. A structural unit (hereinafter, also simply referred to as “component (a4)”) can be included.

  As a component (a4), a well-known thing can be used unless the effect of this invention is impaired.

  For example, an unsaturated carboxylic acid can be used as the component (a4). Examples of such unsaturated carboxylic acids include (meth) acrylic acid, maleic acid, maleic anhydride, fumaric acid, fumaric anhydride, crotonic acid, itaconic acid, itaconic anhydride, myristoleic acid, palmitoleic acid, and oleic acid Is mentioned. Among these, (meth) acrylic acid, maleic acid, maleic anhydride, fumaric acid, fumaric anhydride, crotonic acid, itaconic acid, itaconic anhydride from the viewpoint of excellent polymerizability with the above-mentioned (meth) acrylate monomer. Etc. are preferable, and (meth) acrylic acid is more preferable. In addition, these can be used individually or in mixture of 2 or more types. In the present invention, the unsaturated carboxylic acid is contained as the component (a4), and the content of the unsaturated carboxylic acid constitutes the (meth) acrylate copolymer (A) from the viewpoint of achieving both durability and reworkability. It is preferably 0% by mass or more and 5% by mass or less, and more preferably 0% by mass or more and 2% by mass or less with respect to 100% by mass of the total amount of the unit.

  In addition, as component (a4), an acrylic monomer having an epoxy group such as glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate; dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, Nt-butylamino Acrylic monomers having amino groups such as ethyl (meth) acrylate and (meth) acryloyloxyethyltrimethylammonium chloride; (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N, N-methylenebis (meth) acrylamide, N- Methylol (meth) acrylamide, dimethyl (meth) acrylamide, diethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, dimethylaminopropyl (meth) acrylamide, Acrylic monomers having amide groups such as acetone (meth) acrylamide; 2-methacryloyloxyethyl diphenyl phosphate (meth) acrylate, trimethacryloyloxyethyl phosphate (meth) acrylate, triacryloyloxyethyl phosphate (meth) acrylate, etc. Acrylic monomer having phosphoric acid group; acrylic monomer having sulfonic acid group such as sodium sulfopropyl (meth) acrylate sodium, sodium 2-sulfoethyl (meth) acrylate, sodium 2-acrylamido-2-methylpropanesulfonate; urethane (meth) Acrylic monomers having urethane groups such as acrylate; 2-acetoacetoxyethyl (meth) acrylate, isobornyl (meth) acrylate, isobornyl (meth) ) Acrylate, dicyclopentenyl (meth) acrylate, dicyclopentanyl (meth) acrylate, acryloyl morphophore, 2-methacryloyloxyethylphthalic acid, tetrahydrofurfuryl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate , Vinyltrimers having silane groups such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (β-methoxyethyl) silane, vinyltriacetylsilane, methacryloyloxypropyltrimethoxysilane; styrene, chlorostyrene, α-methylstyrene, vinyl Examples include toluene, vinyl chloride, vinyl acetate, vinyl propionate, acrylonitrile, vinyl pyridine and the like.

  In addition, what was mentioned above can be used individually or in mixture of 2 or more types as a component (a4). Moreover, when manufacturing the (meth) acrylate copolymer (A) which concerns on this invention, from a viewpoint that reaction with the crosslinking agent mentioned later can be controlled easily, as a component (a4), it is a copolymerizable problem. From the viewpoint of difficulty in increasing the molecular weight, it is preferable not to contain an olefin monomer.

  In the copolymer (A) according to the present invention, among the components containing the (a1), (a2) and (a3) (that is, the components (a1) to (a4)), the glass transition temperature of the homopolymer is It is preferable to contain (selectively) a structural unit derived from a (meth) acrylic monomer having a temperature of 50 ° C. or higher (hereinafter also simply referred to as “component (a ′)”). Such a component (a ′) can ensure the hardness of the pressure-sensitive adhesive layer at room temperature that requires dent resistance, and softens and adheres at 80 ° C. or higher, which is a heat durability test temperature at which warpage occurs. In addition to being able to suppress warpage by imparting stress relaxation properties to the agent layer, it is excellent in polymerizability with the (meth) acrylate monomer described above, and can improve durability and adhesion (particularly reworkability). Further, light leakage can be sufficiently suppressed, and further, the generation of warpage and dents can be suppressed.

((Meth) acrylic (co) polymer (H))
In the pressure-sensitive adhesive composition for an optical film according to the present invention, in addition to the (meth) acrylate copolymer (A), the weight average molecular weight (Mw) is more than that of the (meth) acrylate copolymer (A). The (meth) acrylic (co) polymer (H) containing a structural unit derived from a (meth) acrylic monomer having a small glass transition temperature of 50 ° C. or higher is preferable. Such a (meth) acrylic (co) polymer (H) is the same as the (meth) acrylate copolymer (A) as an acrylic resin, but has a low molecular weight separately from the high softening point resin (G). Formed by using the pressure-sensitive adhesive composition for an optical film containing the (meth) acrylic (co) polymer (H) because the component (meth) acrylic (co) polymer (H) exists separately. It is excellent in that it can move freely in the pressure-sensitive adhesive layer and can easily impart stress relaxation properties. In addition, unlike the high softening point resin (G), since it is the same acrylic component as the (meth) acrylate copolymer (A), the compatibility is good and the adhesive layer uses the high softening point resin (G). It is excellent in that it is less likely to become cloudy (preferably no longer cloudy) compared to the case where it is present (although it may be less cloudy). Therefore, by adding the (meth) acrylic (co) polymer (H) and having the above-mentioned properties, the hardness of the pressure-sensitive adhesive layer at room temperature that requires dent resistance is ensured. It is excellent in that it can be softened at a heat durability test temperature of 80 ° C. or higher at which warpage occurs and the pressure-sensitive adhesive layer has stress relaxation properties to suppress warpage.

(Weight average molecular weight of (meth) acrylic (co) polymer (H))
The weight average molecular weight (Mw) of the (meth) acrylic (co) polymer (H) is not particularly limited as long as the weight average molecular weight (Mw) is smaller than the (meth) acrylate copolymer (A), It is preferably 500 or more and 100,000 or less, more preferably 800 or more and 80,000 or less, and further preferably 1,000 or more and 50,000 or less. This is because the components of the low molecular weight (meth) acrylic (co) polymer (H) in the above range are similar to the high molecular weight (meth) acrylate copolymer (A), Since it exists separately, the inside of an adhesive layer can be moved freely and it becomes easy to provide stress relaxation property. In addition, since it is the same acrylic component as the high molecular weight (meth) acrylate copolymer (A), the compatibility is good and the adhesive layer is less likely to become cloudy (preferably not cloudy). preferable.

  In the pressure-sensitive adhesive composition for an optical film according to the present invention, the component (a ′) is contained in the (meth) acrylate copolymer (A), and in addition to the (meth) acrylate copolymer (A), The (meth) acrylic (co) polymer (H) may be contained.

  In the present invention, in order to efficiently exhibit the effects of the component (a ′) and the (meth) acrylic (co) polymer (H) which are components having a glass transition temperature of 50 ° C. or higher, the glass transition temperature is The component of 50 ° C. or higher may be a component of the (meth) acrylate copolymer (A), or the (meth) acrylic (co) separately from the (meth) acrylate copolymer (A). It may exist as a polymer (H). That is, the component of the other (meth) acrylate copolymer (A) and the component (a ′) may be copolymerized with other (meth) acrylate copolymer (A) by multi-stage polymerization. Component (a ′) may be polymerized, or (meth) acrylic (co) polymer (H) may be blended separately from (meth) acrylate copolymer (A).

  In the present invention, the structure of the (meth) acryl monomer used in the component (a ′) or the (meth) acrylic (co) polymer (H), wherein the homopolymer has a glass transition temperature of 50 ° C. or higher. There is no particular limitation as long as the glass transition temperature of the homopolymer is 50 ° C. or higher.

  Of these, the (meth) acrylic (co) polymer (H) has the following constitution. That is, as the (meth) acrylic monomer constituting the (meth) acrylic (co) polymer (H), specifically, for example, isobornyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclo Pentanyl (meth) acrylate, acrylonitrile, (meth) acrylamide, N-methylol (meth) acrylamide, dimethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, diethyl (meth) acrylamide, dimethylaminopropyl (meth) acrylamide, Diacetone (meth) acrylamide, acryloyl morphophore, 2-methacryloyloxyethyl phthalic acid, tetrahydrofurfuryl (meth) acrylate, methyl (meth) acrylate, dicyclopentenyloxyethyl (meth) Acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, 2-methyl-2-nitropropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, S -Butyl (meth) acrylate, t-butyl (meth) acrylate, n-pentyl (meth) acrylate, t-pentyl (meth) acrylate, 3-pentyl (meth) acrylate, 2,2-dimethylbutyl (meth) acrylate, n-hexyl (meth) acrylate, cetyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 4-methyl-2-propylpentyl (meth) acrylate, N-octadecyl (meth) acrylate Such (Meth) acrylic acid (1-20 carbon atoms) alkyl esters, for example, cycloalkyl (meth) acrylate (eg, cyclohexyl (meth) acrylate, cyclopentyl (meth) acrylate, etc.), aralkyl (meth) acrylate (eg, , Benzyl (meth) acrylate, etc.), polycyclic (meth) acrylate (for example, 2-isobornyl (meth) acrylate, 2-norbornylmethyl (meth) acrylate, 5-norbornen-2-yl-methyl (meth) Acrylate, 3-methyl-2-norbornylmethyl (meth) acrylate, etc.), hydroxyl group-containing (meth) acrylic acid esters (for example, hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2, 3-dihydroxy group Propylmethyl-butyl (meth) methacrylate, etc.), alkoxy group or phenoxy group-containing (meth) acrylic acid esters (2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2-methoxymethoxyethyl (meth)) Acrylate, 3-methoxybutyl (meth) acrylate, ethyl carbitol (meth) acrylate, phenoxyethyl (meth) acrylate, etc.), epoxy group-containing (meth) acrylic acid esters (for example, glycidyl (meth) acrylate, etc.), halogen Containing (meth) acrylic acid esters (for example, 2,2,2-trifluoroethyl (meth) acrylate, 2,2,2-trifluoroethylethyl (meth) acrylate, tetrafluoropropyl (meth) acrylate, hexa Ruoropuropiru (meth) acrylate, octafluoropentyl (meth) acrylate, heptadecafluorodecyl (meth) acrylate), alkylaminoalkyl (meth) acrylates (e.g., dimethylaminoethyl (meth) acrylate, etc.) and the like. These (meth) acrylic monomers can be used alone or in combination of two or more. Specific examples of acrylic oligomers include “ARUFON (registered trademark)” manufactured by Toagosei Co., Ltd., “Act Flow (registered trademark)” manufactured by Soken Chemical Co., Ltd., “JONCRYL (registered trademark)” manufactured by BASF Japan Ltd. Or the like. Among these structures, those having a glass transition temperature of 50 ° C. or higher and 200 ° C. or lower are preferably used.

  Regarding a part of specific examples of the (meth) acryl monomer used in the component (a ′) or the (meth) acrylic (co) polymer (H), the homopolymer has a glass transition temperature of 50 ° C. or higher. Although the specific example which showed the glass transition temperature of the homopolymer using the said monomer in the parenthesis after the specific monomer is illustrated, it is not restrict | limited to these. Examples of the (meth) acrylic monomer having a glass transition temperature of 50 ° C. or higher used in the component (a ′) or the (meth) acrylic (co) polymer (H) include isobonyl. Acrylate (Tg94 ° C), dicyclopentenyl acrylate (Tg120 ° C), dicyclopentanyl acrylate (Tg120 ° C), acrylonitrile (Tg97 ° C), acrylamide (Tg165 ° C), N-methylolacrylamide (Tg150 ° C), dimethylacrylamide (Tg119) Deg. 5 ° C.), 2-methacryloyloxyethylphthalic acid (Tg 55 ° C.), methyl methacrylate (Tg 105 ° C.), ethyl methacrylate (Tg 65 ° C.), t-butyl methacrylate (Tg 107 ° C.), cyclohexyl methacrylate (Tg 66 ° C.), tetrahydrofluor Examples include furyl methacrylate (Tg 60 ° C.), benzyl methacrylate (Tg 54 ° C.), isobornyl methacrylate (Tg 180 ° C.), dicyclopentenyloxyethyl methacrylate (Tg 50 ° C.), and dicyclopentanyl methacrylate (Tg 175 ° C.). In addition, these can be used individually or in mixture of 2 or more types.

  Content of the component (a ′) in the (meth) acrylate copolymer (A) according to the present invention (blending amount of (meth) acrylic monomer having a glass transition temperature of a homopolymer as a raw material monomer of 50 ° C. or higher) Is preferably 0% by mass or more and 20% by mass or less from the viewpoint of more efficiently achieving the effect of the present invention with respect to 100% by mass of the total amount of the structural units constituting the (meth) acrylate copolymer (A). More preferably, it is 0.1 mass% or more and 15 mass% or less, Most preferably, it is 0.5 mass% or more and 10 mass% or less. When the content of the component (a ′) is 20% by mass or less, it is preferable from the standpoint that it is easy to balance the dent and warpage suppression. The content of the component (a ′) is included in part (or all) of the content of each component including the components (a1), (a2), and (a3).

  The content of the (meth) acrylic (co) polymer (H) according to the present invention is more effective in achieving the effects of the present invention with respect to 100% by mass of the total pressure-sensitive adhesive composition for optical films. The content is preferably 20% by mass or less, more preferably 0.1% by mass or more and 15% by mass or less, and particularly preferably 0.5% by mass or more and 10% by mass or less. When the content of the (meth) acrylic (co) polymer (H) is 20% by mass or less, it is preferable from the standpoint that it is easy to balance both strike and warp suppression.

  The glass transition temperature of the homopolymer obtained from the component (a ′) or the (meth) acrylic monomer used in the (meth) acrylic (co) polymer (H) may be 50 ° C. or higher. From the viewpoint of increasing the possibility of achieving a balance between dents and warpage suppression, 50 ° C. or higher and 200 ° C. or lower is preferable, 50 ° C. or higher and 150 ° C. or lower is more preferable, and 60 ° C. or higher and 120 ° C. or lower is more preferable. The glass transition temperature is a value measured by differential scanning calorimetry of the homopolymer (homopolymer).

  In the (meth) acrylate copolymer (A) according to the present invention, the total amount of the components (a1), (a2), (a3) and (a4) is 100% by mass. The content (the total content when a plurality of components are blended as the optional component (a4)) is preferably 0% by mass or more and 5% by mass or less from the viewpoint of more efficiently achieving the effects of the present invention. More preferably, it is 0.1 mass% or more and 4 mass% or less, Most preferably, it is 0.2 mass% or more and 3 mass% or less.

  As for the (meth) acrylate copolymer (A) described above, only one type of copolymer may be used alone, or two or more types of copolymers may be used in combination.

[Method for Producing (Meth) acrylate Copolymer (A)]
Next, the manufacturing method of a (meth) acrylate copolymer (A) is demonstrated. In the present invention, the production method of the (meth) acrylate copolymer (A) is not particularly limited, and is a solution polymerization method using a polymerization initiator, a bulk polymerization method, an emulsion polymerization method, a suspension polymerization method, a reverse phase suspension. Conventionally known methods such as a polymerization method, a thin film polymerization method, and a spray polymerization method can be used. Examples of the polymerization control method include adiabatic polymerization, temperature controlled polymerization, and isothermal polymerization. As the polymerization initiator, either a thermal polymerization initiator or a photopolymerization initiator may be used. Further, in addition to or in addition to the method of initiating polymerization with a polymerization initiator, a method of initiating polymerization by irradiating active energy rays such as radiation, electron beams, and ultraviolet rays may be employed. Among these, a solution polymerization method using a thermal polymerization initiator or a bulk polymerization method using a photopolymerization initiator is more preferable because the molecular weight can be easily adjusted and impurities can be reduced. In addition, regarding the manufacturing method of the (meth) acrylic-type (co) polymer (H) which has a structural unit derived from the (meth) acrylic monomer whose glass transition temperature of the above homopolymer is 50 degreeC or more, the monomer to be used, It can be produced in the same manner as the production method of the (meth) acrylate copolymer (A) except that the polymerization conditions such as the amount and type of the polymerization initiator are changed.

  In the solution polymerization method using a thermal polymerization initiator, (a1) an alkyl (meth) acrylate monomer that is a raw material of the (meth) acrylate copolymer (A), (a2) a (meth) acrylate monomer having a hydroxyl group, and (A3) (meth) acrylate monomer having an aromatic ring, and (a4) a raw material monomer comprising monomers other than (a1) to (a3) optionally contained (in these (a ′) homopolymer glass A thermal polymerization initiator is added to the solution (which may contain a (meth) acrylic monomer having a transition temperature of 50 ° C. or higher), and a polymerization reaction is performed. More specifically, using ethyl acetate, toluene, methyl ethyl ketone or the like as a solvent, and preferably adding 0.01% by mass or more and 1% by mass or less of a thermal polymerization initiator to the total amount of raw material monomers of 100% by mass, In a nitrogen atmosphere, for example, a method of reacting at a reaction temperature of 40 ° C. to 90 ° C. (or 60 ° C. to 90 ° C.) for 3 hours to 10 hours is exemplified.

  Examples of the thermal polymerization initiator include 2,2′-azobisisobutyronitrile (AIBN), 2,2′-azobis (2-methylbutyronitrile), azobiscyanovaleric acid, 2,2′-azobis ( 4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis (2.4-dimethylvaleronitrile), dimethyl 2,2'-azobis (2-methylpropionate), 2,2'- Azobis (2-methylbutyronitrile), 1,1′-azobis (cyclohexane-1-carbonitrile), 2,2′-azobis [N- (2-propenyl) -2-methylpropionamide], 2,2 '-Azobis (N-butyl-2-methylpropionamide), 2,2'-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride, 2,2'-a Bis [2- (2-imidazolin-2-yl) propane] disulfate dihydrate, 2,2′-azobis (2-methylpropionamidine) dihydrochloride, 2,2′-azobis [N- (2-carboxyethyl)- 2-Methylpropionamidine] hydrate, 2,2′-azobis [2- (2-imidazolin-2-yl) propane], 2,2′-azobis (1-imino-1-pyrrolidino-2-methylpropane) Azo compounds such as dihydrochloride, 2,2′-azobis [2-methyl-N- (2-hydroxyethyl) propionamide]; t-butyl peroxypivalate, t-butyl peroxybenzoate, t-butyl peroxy 2-ethylhexanoate, di-t-butyl peroxide, cumene hydroperoxide Organic peroxides such as benzoyl peroxide and t-butyl hydroperoxide; inorganic peroxides such as hydrogen peroxide, ammonium persulfate, potassium persulfate and sodium persulfate. These thermal polymerization initiators may be used alone or in combination of two or more.

  In the bulk polymerization method using a photopolymerization initiator, for example, a raw material monomer and a photopolymerization initiator are added, and an active energy ray is irradiated at a reaction start temperature of 20 ° C. to 35 ° C. in a nitrogen atmosphere. When the temperature in the reaction system rises by 5 ° C. or more and 15 ° C. or less from the reaction start temperature, the reaction is stopped by introducing air into the reaction system to obtain the (meth) acrylate copolymer (A). A method is mentioned.

Examples of active energy rays used in the bulk polymerization method include, for example, ultraviolet rays, laser rays, α rays, β rays, γ rays, X rays, electron rays, etc., but good controllability and handling properties, cost From this point, ultraviolet rays are preferably used. More preferably, ultraviolet rays having a wavelength of 200 nm to 400 nm are used. Ultraviolet rays can be irradiated using a light source such as a high-pressure mercury lamp, a microwave excitation lamp, a chemical lamp, or a black light. The illuminance is preferably 3.2 mW / cm ² or more and 5.6 mW / cm ² or less.

  Examples of the photopolymerization initiator include acetophenone, 3-methylacetophenone, benzyldimethyl ketal, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1- (4-isopropylphenyl) -2-hydroxy- 2-methylpropan-1-one, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, etc. Benzophenones such as benzophenone, 4-chlorobenzophenone and 4,4′-diaminobenzophenone; benzoin ethers such as benzoin propyl ether and benzoin ethyl ether; thioxanthones such as 4-isopropylthioxanthone; Cyclohexylpheny Ketone, xanthone, fluorenone, camphor quinone, benzaldehyde, such as anthraquinone, and the like. These photopolymerization initiators may be used alone or in combination of two or more.

  Commercially available photopolymerization initiators may be used. Examples of commercially available products include Irgacure (registered trademark) 184, 819, 907, 651, 1700, 1800, 819, 369, 261, Darocur (registered trademark) TPO. , Darocur (registered trademark) 1173 (above, manufactured by BASF Japan Ltd.), Ezacure (registered trademark) KIP150, TZT (above, manufactured by DKSH Japan Ltd.), Kayacure (registered trademark) BMS, DMBI (above, Nippon Kayaku Co., Ltd.) Company-made).

  The use amount of the photopolymerization initiator is preferably 0.0005% by mass or more and 1% by mass or less, more preferably 0.002% by mass or more and 0.5% by mass or less with respect to 100% by mass of the total amount of raw material monomers. is there.

  A chain transfer agent can also be used to adjust the molecular weight of the (meth) acrylate copolymer (A). For example, methyl mercaptan, t-butyl mercaptan, decyl mercaptan, benzyl mercaptan, stearyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, mercaptoacetic acid, mercaptopropionic acid and esters thereof, 2-ethylhexylthioglycol, octylthioglycolate, etc. Mercaptans; alcohols such as methanol, ethanol, propanol, n-butanol, isopropanol, t-butanol, hexanol, benzyl alcohol, allyl alcohol; halogenated hydrocarbons such as chloroethane, fluoroethane, trichloroethylene; acetone, methyl ethyl ketone, Cyclohexanone, acetophenone, acetaldehyde, propionaldehyde, n-butyraldehyde Furfural, carbonyls, such as benzaldehyde; methyl-4-cyclohexene-1,2-dicarboxylic acid anhydride, such as α- methyl styrene. These may be used alone or in combination of two or more.

<Isocyanate compound (B)>
The optical film pressure-sensitive adhesive composition of the present invention contains an isocyanate compound (B) as an essential component. The isocyanate compound (B) according to the present invention has a number average molecular weight (Mn) of 900 or more and 10,000 or less. By containing such an isocyanate compound (B), the distance between cross-linking points is long while suppressing the densification of the cross-linked structure of the (meth) acrylate copolymer (A) according to the present invention described above. A crosslinking effect can be expressed. This makes it possible to achieve both suppression of foaming and suppression of peeling as heat durability, and also suppress the occurrence of warpage and dents, and is excellent in durability.

  In addition, when an isocyanate compound having a number average molecular weight (Mn) of less than 900 is used as the isocyanate compound (B) according to the present invention, the distance between the crosslinking points is short and the cross-linking structure is densely formed, so that the number average molecular weight (Mn) is When an isocyanate compound exceeding 10,000 is used, it becomes difficult to ensure high durability because the distance between the crosslinking points becomes too long. On the other hand, from the viewpoint of further exerting the effects of the present invention, the number average molecular weight (Mn) is preferably 900 or more and 7,000 or less, and more preferably 1,000 or more and 5,000 or less. . In addition, the number average molecular weight (Mn) of an isocyanate compound (B) can be calculated | required by the method similar to the measuring method of the number average molecular weight of the (meth) acrylate copolymer (A) shown in an Example.

  As an isocyanate compound (B) which concerns on this invention, what is obtained by synthesize | combining may be used and a commercial item may be used as it is.

  For example, an isocyanate compound obtained by reacting a polyhydric alcohol and an excess amount of an isocyanate monomer can be used. In addition, an isocyanate compound having a number average molecular weight of 900 or more and 10,000 or less can be obtained by appropriately adjusting the molecular weight or reaction charge ratio of the polyhydric alcohol and isocyanate monomer to be reacted.

  Here, as polyhydric alcohol, for example, ethylene glycol, propylene glycol, diethylene glycol, trimethylene glycol, tetraethylene glycol, triethylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, 2 , 3-butanediol, 1,2-butanediol, 3-methyl-1,2-butanediol, 1,2-pentanediol, 1,5-pentanediol, 1,4-pentanediol, 2,4-pentane Diol, 2,3-dimethyltrimethylene glycol, tetramethylene glycol, 3-methyl-4,3-pentanediol, 3-methyl-4,5-pentanediol, 2,2,4-trimethyl-1,3-pentane Diol, 1,6-hexanediol, 1,5-he Dihydric alcohols such as sundiol, 1,4-hexanediol, 2,5-hexanediol, neopentyl glycol, and hydroxypivalic acid neopentyl glycol ester; lactones such as ε-caprolactone are added to the dihydric alcohol Polylactone diols; ester diols such as bis (hydroxyethyl) terephthalate, polyethylene adipate diol (PEA), polyethylene sebacate diol (PES); alkylene oxide adducts of bisphenol A, polyethylene glycol, polypropylene glycol, polybutylene glycol, etc. Polyether diols; α-olefin epoxides such as propylene oxide and butylene oxide, and Cardura E10 (trade name) (shell formation) A polyhydric alcohol formed by reacting a monoepoxy compound (such as a glycidyl ester of a synthetic highly branched saturated fatty acid) with an acid; glycerin, trimethylolpropane, trimethylolethane, diglycerin, triglycerin, 1,2,6 -Trivalent or higher alcohols such as hexanetriol, pentaerythritol, dipentaerythritol, sorbitol, mannitol; polylactone polyols obtained by adding lactones such as ε-caprolactone to the trivalent or higher alcohols; 1,4- Examples include, but are not limited to, cyclohexanedimethanol, tricyclodecanedimethanol, hydrogenated bisphenol A, and hydrogenated bisphenol F.

  That is, as the isocyanate compound (B) according to the present invention, to the above polyhydric alcohol, tolylene diisocyanate (TDI), 4,4′-diphenylmethane diisocyanate (MDI), dicyclohexylmethane diisocyanate (HMDI), hexamethylene diisocyanate, isophorone. Additives obtained by reacting isocyanate monomers such as diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated diphenylmethane diisocyanate, tetramethyl xylylene diisocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate, polymethylene polyphenyl isocyanate For example, polyoxytetramethylene glycol (PTMG) of tolylene diisocyanate Adduct, 4,4'-diphenylmethane diisocyanate polyoxytetramethylene glycol (PTMG) adduct, 4,4'-diphenylmethane diisocyanate polyethylene adipate diol (PEA) and polycaprolactone diol (PCL) adduct, dicyclohexylmethane diisocyanate Examples thereof include polyoxytetramethylene glycol (PTMG) adducts and polypropylene glycol (PPG) adducts of tolylene diisocyanate. Among them, polyoxytetramethylene glycol (PTMG) adduct of tolylene diisocyanate, polyoxytetramethylene glycol (PTMG) adduct of 4,4′-diphenylmethane diisocyanate, polyethylene adipate diol (PEA) of 4,4′-diphenylmethane diisocyanate And polycaprolactone diol (PCL) adducts, polycyclohexyltetramethylene glycol (PTMG) adducts of dicyclohexylmethane diisocyanate, and polypropylene glycol (PPG) adducts of tolylene diisocyanate improve heat durability and ensure wet heat durability. From the viewpoint of Among them, polyoxytetramethylene glycol (PTMG) adduct of tolylene diisocyanate, polyoxytetramethylene glycol (PTMG) adduct of 4,4′-diphenylmethane diisocyanate, polypropylene glycol (PPG) adduct of tolylene diisocyanate, Polypropylene glycol (PPG) adducts of 4,4′-diphenylmethane diisocyanate are preferable from the viewpoints of suppressing the occurrence of warpage and dents and being excellent in durability and reworkability.

  In the case of synthesizing the isocyanate compound (B), for example, polyoxytetramethylene glycol (PTMG) is dehydrated at 100 ° C. for 1 hour under reduced pressure (4 kPa) in a reaction vessel equipped with a stirrer and a temperature controller. Cooled to 40 ° C., charged with 2,4-tolylene diisocyanate (“TDI-100” manufactured by Nippon Polyurethane Industry Co., Ltd.), gradually heated to 70 ° C. with stirring under a nitrogen stream, and heated at the same temperature to 7 Examples include those that have been reacted for a long time. As reaction conditions, it is preferable to react for 2 hours to 10 hours at a reaction temperature of 60 ° C. or higher and 100 ° C. or lower in a nitrogen atmosphere.

  When using a commercially available product as the isocyanate compound (B) according to the present invention, for example, a commercially available product name: “Samprene (registered trademark) P-6090” (PTMG / MDI), “SAMPLEN (registered trademark) P-7315” (PEA-PCL / MDI system), “SAMPLEN (registered trademark) P-663L” (PTMG / TDI system), “SAMPLEN (registered trademark) P-664” (PTMG / TDI system), "Samprene (registered trademark) P-665" (PTMG / TDI system), "Samprene (registered trademark) P-667 system" (PTMG / TDI system), "Samprene (registered trademark) P-868" "(PTMG / HMDI system)", "Samprene (registered trademark) P-870" (PTMG / HMDI system), "Samprene (registered trademark) C-810" (PP / TDI-based), and the like, but not limited thereto.

  In the present invention, the NCO% of the isocyanate compound (B) is not particularly limited, but is preferably 0.5% or more and 20% or less, more preferably 0.5% or more and 15% or less. It is particularly preferably 0% or more and 10% or less. If NCO% is 0.5% or more, the above-described (meth) acrylate copolymer (A) according to the present invention can be sufficiently cross-linked and contribute to the effect of heat resistance (foaming resistance). . Moreover, if NCO% is 20% or less, it can endure the contraction and expansion | swelling of a polarizing plate at the time of a heating or wet heat, and can contribute to the effect which suppresses peeling. It can also contribute to the effect of suppressing the occurrence of dents. NCO% can be determined by the method described in the examples.

  In this invention, content of an isocyanate compound (B) is not specifically limited, From a viewpoint of making the effect of this invention exhibit more, with respect to 100 mass parts of (meth) acrylate copolymers (A) mentioned above. , Preferably 0.01 parts by weight or more and 20 parts by weight or less, more preferably 0.05 parts by weight or more and 15 parts by weight or less, and further preferably 0.1 parts by weight or more and 10 parts by weight or less. It is particularly preferable that the content is 0.2 parts by mass or more and 8 parts by mass or less. If content of an isocyanate compound (B) is 0.01 mass part or more, heat resistance (foaming resistance) can fully be expressed, without a crosslinked structure being insufficient. On the other hand, if it is 20 parts by mass or less, it effectively suppresses the density of the crosslinked structure, sufficiently suppresses peeling during the heat durability test and the wet heat durability test, and generates warpage and dents. Can be suppressed.

<Crosslinking agent (C)>
It is preferable that the adhesive composition for optical films of this invention further contains crosslinking agents (C) other than the isocyanate compound (B) mentioned above. Here, what is defined as “crosslinking agent (C) other than isocyanate compound (B)” is distinguished from “isocyanate compound (B)” having an effect of crosslinking (meth) acrylate copolymer (A). It is to do. In the present specification, “crosslinking agent (C) other than isocyanate compound (B)” is also simply referred to as “crosslinking agent (C)”. As described above, the isocyanate compound (B) can gently crosslink the (meth) acrylate copolymer (A), whereas here, the isocyanate compound (B) is durable by further containing the crosslinker (C). The sex can be improved.

  In the present invention, the crosslinking agent (C) preferably contains at least one selected from the group consisting of a carbodiimide crosslinking agent, an oxazoline crosslinking agent, an epoxy crosslinking agent, an aziridine crosslinking agent, and an isocyanate crosslinking agent. . The inclusion of these crosslinking agents is preferable because the above-described effects of containing the crosslinking agent (C) can be further exhibited. Below, various crosslinking agents are demonstrated.

[Isocyanate-based crosslinking agent]
If the isocyanate-based crosslinking agent suitably used as the crosslinking agent (C) is other than the above-mentioned isocyanate compound (B) (that is, one having a number average molecular weight of less than 900 or more than 10,000), in particular. For example, tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, tetramethylxylylene diisocyanate, naphthalene diisocyanate, Adducts, burettes, and isocyanurates of isocyanate monomers such as phenylmethane triisocyanate and polymethylene polyphenyl isocyanate In consideration of the crosslinking rate and compatibility with the (meth) acrylate copolymer (A), trimethylolpropane adduct of tolylene diisocyanate, trimethylolpropane adduct of hexamethylene diisocyanate, trimethylol of isophorone diisocyanate Propane adduct, xylylene diisocyanate trimethylolpropane adduct, tolylene diisocyanate isocyanurate, hexamethylene diisocyanate isocyanurate, isophorone diisocyanate isocyanurate, xylylene diisocyanate or tolylene diisocyanate trimethylolpropane Adduct bodies are particularly preferred. Moreover, these isocyanate type crosslinking agents may be used independently and may be used in combination of 2 or more type. When such an isocyanate-based crosslinking agent is used, the isocyanate group should be contained in a ratio of 0.05 to 100 mol with respect to 1 mol of the hydroxyl group of the (meth) acrylate copolymer (A). Is preferred.

  Moreover, what was synthesized may be used for these isocyanate type crosslinking agents, and a commercial item may be used.

  Examples of commercially available products include Coronate (registered trademark) L, Coronate (registered trademark) HL, Coronate (registered trademark) HX, Coronate (registered trademark) 2030, Coronate (registered trademark) 2031 (manufactured by Tosoh Corporation), Takenate (registered trademark) D-102, Takenate (registered trademark) D-110N, Takenate (registered trademark) D-200, Takenate (registered trademark) D-202 (manufactured by Mitsui Chemicals, Inc.), Duranate (registered trademark) 24A-100, Duranate (registered trademark) TPA-100, Duranate (registered trademark) TKA-100, Duranate (registered trademark) P301-75E, Duranate (registered trademark) E402-90T, Duranate (registered trademark) E405-80T, Duranate (Registered trademark) TSE-100, Duranate (Registered) Standard) D-101, Duranate (registered trademark) D-201 (above, manufactured by Asahi Kasei Chemicals Corporation), Sumidur (registered trademark) N-75, N-3200, N-3300 (above, Sumika Bayer Urethane Co., Ltd.) ) And the like. Among these, Coronate (R) L, Coronate (R) HL, Coronate (R) HX, Takenate (R) D-110N, Duranate (R) 24A-100, Duranate (R) TPA -100. Among these, Takenate (registered trademark) D-110N, Coronate (registered trademark) L, Coronate (registered trademark) HX, and Duranate (registered trademark) 24A-100 are preferable.

  Further, these isocyanate-based crosslinking agents may be used in the form of an unblocked isocyanate compound, or may be used in the form of a blocked isocyanate compound obtained by reacting with a blocking agent that protects an isocyanate group. Good. The blocked isocyanate compound using such a blocking agent may be one obtained by synthesis or a commercially available product. Commercially available products include Duranate (registered trademark) MF-B60X (block 1,6-hexamethylene diisocyanate), Duranate (registered trademark) MF-K60X (block 1,6-hexamethylene diisocyanate), Tosoh manufactured by Asahi Kasei Chemicals Corporation. Coronate (registered trademark) AP-M, 2503, 2507, 2513, 2515, Millionate (registered trademark) MS-50 manufactured by Co., Ltd., Takenate (registered trademark) B-830 manufactured by Mitsui Chemicals, Inc. -G), B-815N (block 4,4'-methylenebis (cyclohexyl isocyanate)), B-842N (block 1,3-bis (isocyanatemethyl) cyclohexane), B-846N (block 1,3-bis (isocyanate)) Methyl) cyclohexa ), B-874N (block isophorone diisocyanate), B-882N (block 1,6-hexamethylene diisocyanate), Vernock (registered trademark) D-500 manufactured by Dainippon Ink & Chemicals, Inc. (Block tolylene diisocyanate), D-550 (block 1,6-hexamethylene diisocyanate), Elastron (registered trademark) BN-P17 (block 4, 4 ′) manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd. -Diphenylmethane diisocyanate), BN-04, BN-08, BN-44, BN-45 (above, block urethane-modified polyvalent isocyanate) and the like. Of these, Duranate (registered trademark) MF-K60X is particularly preferable.

  In the present invention, in the case of blocked isocyanate, the number average molecular weight of only the isocyanate moiety when the blocking agent is removed is treated as the molecular weight of the crosslinking agent (C). The reason for this is that in the crosslinking agent of the present invention, the molecular weight of the crosslinking agent moiety incorporated into the network of polymer chains plays a major role in its effect. This is because it is better not to incorporate it.

  From the viewpoint of further improving the durability of the pressure-sensitive adhesive composition, the isocyanate-based crosslinking agent is preferably used in the form of an unblocked isocyanate compound.

[Carbodiimide crosslinking agent]
In the present invention, the carbodiimide-based crosslinking agent is not particularly limited. For example, a high molecular weight polycarbodiimide produced by decarboxylation condensation reaction of diisocyanate in the presence of a carbodiimidization catalyst is used.

  Examples of the diisocyanate used in the decarboxylation condensation reaction include 4,4′-diphenylmethane diisocyanate, 3,3′-dimethoxy-4,4′-diphenylmethane diisocyanate, and 3,3′-dimethyl-4,4′-. Diphenylmethane diisocyanate, 4,4′-diphenyl ether diisocyanate, 3,3′-dimethyl-4,4′-diphenyl ether diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1-methoxyphenyl-2,4 -Diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, tetramethylxylylene diisocyanate and the like.

  Examples of the carbodiimidization catalyst used in the decarboxylation condensation reaction include 1-phenyl-2-phospholene-1-oxide, 3-methyl-2-phospholene-1-oxide, 1-ethyl-3-methyl- Examples include 2-phospholene-1-oxide, 1-ethyl-2-phospholene-1-oxide, and phospholene oxides such as these 3-phospholene isomers.

  The high molecular weight polycarbodiimide may be a synthesized product or a commercially available product.

  Examples of commercially available products include Carbodilite (registered trademark) series manufactured by Nisshinbo Chemical Co., Ltd. Among these, Carbodilite (registered trademark) V-01, V-03, V-05, V-07, and V-09 are preferable because of excellent compatibility with organic solvents.

[Oxazoline crosslinking agent]
In the present invention, the oxazoline-based crosslinking agent is not particularly limited, but includes an oxazoline group-containing acrylic / styrene polymer having a main chain composed of an acrylic skeleton or a styrene skeleton, and having an oxazoline group in a side chain of the main chain. An oxazoline group-containing polymer such as an oxazoline group-containing acrylic polymer containing a main chain composed of an acrylic skeleton and having an oxazoline group in the side chain of the main chain is preferably used.

  Examples of the oxazoline group include a 2-oxazoline group, a 3-oxazoline group, and a 4-oxazoline group, and among them, a 2-oxazoline group is preferable.

  The oxazoline group-containing polymer may have a polyoxyalkylene group in addition to the oxazoline group.

  Specific examples of the oxazoline group-containing polymer include oxazoline group-containing acrylics such as EPOCROS (registered trademark) WS-300, EPOCROSS (registered trademark) WS-500, and EPOCROSS (registered trademark) WS-700 manufactured by Nippon Shokubai Co., Ltd. Examples thereof include oxazoline group-containing acrylic / styrene polymers such as EPOCROSS (registered trademark) K-1000 series and EPOCROSS (registered trademark) K-2000 series manufactured by Nippon Shokubai Co., Ltd.

[Epoxy-based crosslinking agent]
In the present invention, the epoxy crosslinking agent is not particularly limited, and a known epoxy crosslinking agent can be appropriately employed. Examples of commercially available products include “TETRAD-C” and “TETRAD-X” manufactured by Mitsubishi Gas Chemical Co., Ltd., “ADEKA RESIN (registered trademark) EPU series” and “ADEKA RESIN (registered trademark) EPR series” manufactured by ADEKA Corporation. And “Celoxide (registered trademark)” manufactured by Daicel Corporation. In particular, the epoxy crosslinking agent is preferably in a liquid state. A liquid epoxy-based crosslinking agent is preferable in terms of facilitating a mixing operation when producing an optical film pressure-sensitive adhesive composition.

[Aziridine-based crosslinking agent]
In the present invention, the aziridine-based crosslinking agent is not particularly limited, but a polyfunctional aziridine compound having a plurality of aziridine rings can be preferably used. Examples of the polyfunctional aziridine compound include U.S. Pat. No. 3,225,013, U.S. Pat. No. 4,490,505, and U.S. Pat. No. 5,534,391. And compounds disclosed in the specification of No. 104970.

  Moreover, as a commercial item of an aziridine type | system | group crosslinking agent, Nippon Shokubai Co., Ltd. Chemitite (trademark) PZ-33, Chemitite (trademark) DZ-22E, etc. are mentioned, for example.

  In the present invention, the crosslinking agent (C) other than the isocyanate compound (B) is selected from the group consisting of an isocyanate crosslinking agent, a carbodiimide crosslinking agent, an oxazoline crosslinking agent, an epoxy crosslinking agent, and an aziridine crosslinking agent. In the case of containing at least one kind, only one kind may be used alone, or two or more kinds may be used in combination. When using 2 or more types together, you may combine 2 or more types (for example, 2 types of isocyanate type crosslinking agents) of the same type | system | group crosslinking agent, and each 1 or more types (for example, isocyanate type) of different types of crosslinking agents. One kind of crosslinking agent and one kind of carbodiimide-based crosslinking agent may be combined.

  The content of the crosslinking agent (C) when the crosslinking agent (C) is included in the pressure-sensitive adhesive composition for optical films of the present invention is not particularly limited, but is 100 parts by weight of the (meth) acrylate copolymer (A). Is preferably 0.001 to 20 parts by mass, more preferably 0.01 to 10 parts by mass, and 0.03 to 5 parts by mass. Is more preferably 0.05 parts by mass or more and 3 parts by mass or less. When the content is 0.01 parts by mass or more, it is preferable from the viewpoint that foaming can be suppressed during heating durability. Moreover, it is preferable from a viewpoint that generation | occurrence | production of a dent can be suppressed. On the other hand, when the content is 10 parts by mass or less, it is preferable from the viewpoint of ensuring durability even in a harsh environment without the cross-linked structure becoming too dense.

<Silane coupling agent (D)>
It is preferable that the adhesive composition for optical films of this invention further contains a silane coupling agent (D). In the pressure-sensitive adhesive composition for optical films, the silane coupling agent (D) can contribute mainly to improving durability and improving adhesion to glass when the adherend is glass. In the present specification, the “silane coupling agent” means a compound having no siloxane bond (Si—O—Si bond) and having two or more reactive groups in the molecule.

  In the present invention, the silane coupling agent (D) is not particularly limited, and specifically, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, methyltrimethoxysilane, dimethyldimethoxy Silane, trimethylmethoxysilane, n-propyltrimethoxysilane, ethyltrimethoxysilane, diethyldiethoxysilane, n-butyltrimethoxysilane, n-hexyltriethoxysilane, n-octyltrimethoxysilane, phenyltrimethoxysilane, diphenyl Dimethoxysilane, cyclohexylmethyldimethoxysilane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, β- (3,4-epoxycyclohexane Syl) ethyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacrylic Roxypropyltrimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-acryloxypropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane , -Phenyl-γ-aminopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, bis- (3- [triethoxysilyl] propyl) tetrasulfide, and γ-isocyanatopropyltriethoxysilane. Furthermore, a silane cup containing a silane coupling agent having a functional group such as an epoxy group (glycidoxy group), amino group, mercapto group, (meth) acryloyl group, and a functional group reactive with these functional groups. A compound having a hydrolyzable silyl group obtained by reacting a ring agent, another coupling agent, polyisocyanate, or the like at an arbitrary ratio with respect to each functional group can also be used.

  The silane coupling agent (D) may be synthesized or a commercially available product may be used. Examples of commercially available silane coupling agents include KBM-303, KBM-403, KBE-402, KBE-403, KBE-502, KBE-503, KBM-5103, KBM-573, KBM-802, and KBM-. 803, KBE-846, KBE-9007 (manufactured by Shin-Etsu Chemical Co., Ltd.) and the like.

  In addition, a silane coupling agent (D) may be used individually by 1 type, and may use 2 or more types together.

  The content of the silane coupling agent (D) when the silane coupling agent (D) is included in the optical film pressure-sensitive adhesive composition of the present invention is not particularly limited, but the (meth) acrylate copolymer (A) Preferably it is 0.001 mass part or more and 10 mass parts or less with respect to 100 mass parts, More preferably, it is 0.005 mass part or more and 5 mass parts or less, More preferably, 0.01 mass part or more and 3 mass parts or less Or less, and particularly preferably 0.01 parts by mass or more and 1 part by mass or less. When the content is 0.001 part by mass or more, it is preferable from the viewpoint that an effect on durability can be exhibited even in a severe environment. On the other hand, when the content is 10 parts by mass or less, it is preferable from the viewpoint that heating foaming derived from the low molecular weight compound is not deteriorated.

<Silicate oligomer (E)>
It is preferable that the adhesive composition for optical films of this invention further contains a silicate oligomer (E). The silicate oligomer (E) can contribute mainly to the improvement of reworkability in the pressure-sensitive adhesive composition for optical films.

  The silicate oligomer (E) according to the present invention has a structure represented by the following chemical formula (1).

In the chemical formula (1), R ¹ and R ² are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a phenyl group. X ¹ and X ² are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or a phenyl group. n is an integer of 1 to 100, preferably an integer of 2 to 100. Such alkyl groups and phenyl groups may be substituted or unsubstituted. Further, the alkyl group may have a straight chain structure or a branched chain structure.

In the present invention, methyl silicate in which R ¹ and R ² and all of X ¹ and X ² are methyl groups among the compounds represented by the chemical formula (1) from the viewpoint that both durability and reworkability are easily achieved. An oligomer is preferable. In addition, as a silicate oligomer (E), only 1 type may be used independently among the compounds shown above, and 2 or more types may be used together.

  In the present invention, the weight average molecular weight of the silicate oligomer (E) is not particularly limited, but is preferably 300 or more and 30,000 or less, more preferably 500 or more and 25,000 or less, and further preferably 600 or more and 5, 000 or less. A weight average molecular weight of 300 or more is preferable from the viewpoint of easily ensuring reworkability. On the other hand, when it is 30,000 or less, it is preferable from the viewpoint that durability is easily ensured even in a severe environment. In addition, a weight average molecular weight can be calculated | required by the method similar to the measuring method of the weight average molecular weight of the (meth) acrylate copolymer (A) shown in an Example.

  The content of the silicate oligomer (E) when the silicate oligomer (E) is contained in the pressure-sensitive adhesive composition for an optical film of the present invention is not particularly limited, but is 100 parts by mass of the (meth) acrylate copolymer (A). On the other hand, it is preferably 0.01 parts by mass or more and 50 parts by mass or less, more preferably 0.3 parts by mass or more and 10 parts by mass or less, and further preferably 0.5 parts by mass or more and 5 parts by mass or less. When the content is 0.01 parts by mass or more, it is preferable in that an effect on durability can be exhibited even in a severe environment. On the other hand, when the content is 50 parts by mass or less, it is preferable in that it is easy to achieve both reworkability and durability.

<Peroxide (F)>
The pressure-sensitive adhesive composition for an optical film of the present invention preferably further contains a peroxide (F) as a crosslinking agent other than the crosslinking agent (C). Here, the peroxide (F) is defined as “a crosslinking agent other than the crosslinking agent (C)” in order to distinguish it from the “crosslinking agent (C)”. Since the peroxide (F) can be crosslinked relatively slowly with the (meth) acrylate copolymer (A), it is possible to more effectively suppress the formation of dents, and at a high temperature, Even if the shrinkage increases, it is preferable in that it is more difficult to peel off and the durability can be further improved.

  As the peroxide (F) suitably used as a crosslinking agent other than the crosslinking agent (C), any peroxide can be used as long as it can generate a radical by heating to achieve crosslinking of the pressure-sensitive adhesive composition. Considering workability and stability, use a peroxide having a half-life temperature of preferably 1 to 125 ° C., more preferably 90 to 125 ° C., and still more preferably 90 to 120 ° C. It is preferable. Conventionally, it has been proposed to use a one-minute half-life temperature of 150 ° C. or higher and 160 ° C. or lower, such as benzoyl peroxide. In such a case, the production line temperature is also 150 ° C. or higher and 160 ° C. Must be in the following range: The pressure-sensitive adhesive composition is usually applied to a separator of a PET film that has been subjected to a release treatment and a release treatment. When the temperature becomes higher than 150 ° C., an oligomer component is precipitated from this separator. As a result, the precipitate becomes a foreign substance, and the appearance is deteriorated or the yield (productivity) is deteriorated. On the other hand, if the one-minute half-life temperature of the peroxide (F) is within the above range, particularly 125 ° C. or less, it becomes a temperature range in which such a foreign matter (precipitate) is not generated (deposited). It is extremely useful in preventing the occurrence of On the other hand, peroxides having a 1 minute half-life temperature lower than 80 ° C. are substantially difficult to obtain. Also, the peroxide becomes very unstable, the pot life of the pressure-sensitive adhesive composition solution is lost, and the reaction may start while the pressure-sensitive adhesive composition solution is blended, which may lead to poor stability. There is. From this point of view, when the half-life temperature of the peroxide (F) is within the above range, particularly 80 ° C. or more, many peroxides are available, and the peroxides are also very stable. Since it is in a temperature range that can be achieved, it is extremely useful in preventing the above-described problems. The peroxide half-life is an index that represents the decomposition rate of the peroxide, and is the time during which the concentration of the peroxide is half of the initial value. The decomposition temperature for obtaining a half-life at an arbitrary time and the half-life at an arbitrary temperature are described in the manufacturer catalog. For example, organic peroxidation issued by Nippon Oil & Fats Co., Ltd. (Nippon Oil Co., Ltd.) Product catalog 9th edition (May 2003).

  Examples of such peroxide (F) include diisobutyl peroxide (1 minute half-life temperature 85.1 ° C.), bis (2-ethylhexyl) peroxydicarbonate (90.6 ° C.), bis (4-t -Butylcyclohexyl) peroxydicarbonate (92.1 ° C.), bis-sec-butylperoxydicarbonate (92.4 ° C.), t-butylperoxyneodecanoate (103.5 ° C.), t-hexylperoxypivalate (109.1 ° C), t-butylperoxypivalate (110.3 ° C), dilauroyl peroxide (116.4 ° C), bis-n-octanoylper Oxide (117.4 ° C.), 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate (124.3 ° C.), bis (4-methylben Yl) peroxide (same 128.2 ° C.), dibenzoyl peroxide (same 130.0 ° C.), t-butyl peroxy butyrate (up 136.1 ° C.), and the like. Of these, bis (4-t-butylcyclohexyl) peroxydicarbonate, dilauroyl peroxide, and dibenzoyl peroxide, which are excellent in cross-linking reaction efficiency, are preferably used. In particular, bis (4-t-butylcyclohexyl) peroxydicarbonate (1 minute half-life temperature 92.1 ° C.) is more preferable from the viewpoint of the decomposition temperature. Moreover, these peroxides (F) may be used individually by 1 type, and may use 2 or more types together.

  In the optical film pressure-sensitive adhesive composition of the present invention, the content of the peroxide (F) when the peroxide (F) is included as a crosslinking agent other than the crosslinking agent (C) is not particularly limited, It is preferably 0.02 to 10 parts by mass, more preferably 0.05 to 7 parts by mass, relative to 100 parts by mass of the (meth) acrylate copolymer (A). More preferably, they are 0.1 mass part or more and 5 mass parts or less. A content of 0.02 parts by mass or more is preferable from the viewpoint that durability can be secured by crosslinking. Moreover, it is preferable from a viewpoint that generation | occurrence | production of curvature and a dent can be suppressed. On the other hand, when the content is 10 parts by mass or less, it is preferable from the viewpoint of ensuring durability even in a harsh environment without the cross-linked structure becoming too dense.

<High softening point resin (G)>
The pressure-sensitive adhesive composition for an optical film of the present invention preferably further contains a high softening point resin (G) having a softening point of 60 ° C. or higher and 200 ° C. or lower (also simply referred to as a high softening point resin (G)). This is because by adding the high softening point resin (G), it is possible to provide a pressure-sensitive adhesive composition that has a characteristic of being hard to some extent at room temperature and softening (softening) at high temperature. Further, the high softening point resin (G) is greatly different from the (meth) acrylate copolymer (A) in terms of the components, and is present separately as a low molecular component, and therefore can move freely in the pressure-sensitive adhesive layer. It is also excellent in that it can easily impart stress relaxation properties. By adding the above-mentioned high softening point resin (G) and having various properties as described above, it can be hardened at room temperature and the occurrence of dents can be effectively suppressed. Moreover, since it softens (becomes soft) at a high temperature, stress relaxation can be imparted in a high temperature (85 ° C.) environment (where warpage is evaluated), so that the occurrence of warpage can be effectively suppressed. This is preferable.

  The high softening point resin (G) used in the present invention is not particularly limited as long as the softening point is 60 ° C. or higher and 200 ° C. or lower from the viewpoint that the above-described effects can be effectively expressed. Therefore, a conventionally well-known thing can be used. Specific examples thereof include, for example, aliphatic petroleum resins, alicyclic hydrocarbon resins, aromatic petroleum resins, fully hydrogenated aliphatic petroleum resins, fully hydrogenated alicyclic hydrocarbon resins, Fully hydrogenated aromatic petroleum resin, partially hydrogenated aliphatic petroleum resin, partially hydrogenated alicyclic hydrocarbon resin, petroleum resin such as partially hydrogenated aromatic petroleum resin, aromatic hydrocarbon resin, aliphatic Rosin resins such as saturated hydrocarbon resins, terpene resins, terpene phenol resins, hydrogenated terpene resins, coumarone-indene resins, rosin acids, polymerized rosin acids and rosin ester resins (rosin acid esters) Preferred), epoxy resins, phenol resins, oil-soluble phenols (resins), or modified resins thereof. These high softening point resins (G) may be used alone or in combination of two or more. Among these, an alicyclic hydrocarbon resin, a terpene phenol resin, and a terpene resin are more preferable from the viewpoint of good compatibility with the (meth) acrylate copolymer (A). Moreover, it is more preferable that it is a rosin ester-type resin from a viewpoint that compatibility with the other component of an adhesive composition is very good, and when it applies to an optical film, transparency is easy to be obtained.

  Specific examples of rosin ester resins include Pine Crystal (registered trademark, the same shall apply hereinafter) KR-85 (softening point 80-87 ° C.), Pine Crystal KR-612 (softening point 80-90 ° C.), Pine Crystal KR-614. (Softening point 84-94 ° C), Pine Crystal KE-100 (Softening point 95-105 ° C), Pine Crystal KE-311 (Softening point 90-100 ° C), Pine Crystal PE-590 (Softening point 90-100 ° C) Pine Crystal KE-359 (softening point 94-104 ° C), Pine Crystal KE-604 (softening point 124-134 ° C), Pine Crystal KR-120 (softening point 110-130 ° C), Pine Crystal KR-140 (softening) 130-150 ° C), Pine Crystal KR-614 (84-94 ° C softening point), In Crystal D-6011 (softening point 84-99 ° C.), Pine Crystal KR-50M (softening point 145-160 ° C.) (both manufactured by Arakawa Chemical Co., Ltd.), these must be transparent as ultra-light rosin It is preferably used for various optical applications.

  Other rosin ester resins include super ester A-75 (softening point 70-80 ° C.), super ester A-100 (softening point 95-105 ° C., super ester A-115 softening point 108-120 ° C.). Superester A-125 (softening point 120-130 ° C.) (both manufactured by Arakawa Chemical Industries, Ltd.) is also preferably used for the adhesive.

  Specific examples of the alicyclic hydrocarbon resin include Archon (registered trademark, the same shall apply hereinafter) P-90 (softening point 85-95 ° C.), Archon P-100 (softening point 95-105 ° C.), Archon P-115. (Softening point 110-120 ° C), Archon P-125 (softening point 120-130 ° C), Archon P-140 (softening point 135-145 ° C), Archon M-90 (softening point 85-95 ° C), Archon M -100 (softening point 95-105 ° C.), Alcon M-115 (softening point 110-120 ° C.), Alcon M-135 (softening point 130-140 ° C.) (all manufactured by Arakawa Chemical Industries, Ltd.) Preferably used.

  Specific examples of the terpene phenol resin include Tamanol (registered trademark, the same shall apply hereinafter) 803L (softening point 145-160 ° C.), Tamanol 901 (softening point 125-135 ° C.), Tamanool 460 (softening point 182-192 ° C.) Manufactured by Arakawa Chemical Industries, Ltd.), YS Polyster (registered trademark, the same shall apply hereinafter) U130 (softening point 125-135 ° C), YS Polyster U115 (softening point 110-120 ° C), (softening point 125-135 ° C), YS Polyster T160 (softening point 155-165 ° C), YS polystar T145 (softening point 140-150 ° C), YS polystar T130 (softening point 125-135 ° C), YS polystar T115 (softening point 110-120 ° C), YS polystar T100 ( Softening point 95-105 ° C), YS polystar T80 (softening point 75-85 ° C), YS Lister S145 (softening point 140-150 ° C.), YS polystar G150 (softening point 145-155 ° C.), YS polystar G125 (softening point 120-130 ° C.), YS polystar N125 (softening point 120-130 ° C.), YS polystar K125 (Softening point 120-130 ° C.) and YS polystar TH130 (softening point 125-135 ° C.) (both manufactured by Yasuhara Chemical Co., Ltd.) are also preferably used for the adhesive.

  Specific examples of the terpene resin include YS resin (registered trademark, hereafter the same) PX1250 (softening point 120-130 ° C.), YS resin PX1150 (softening point 110-120 ° C.), YS resin PX1000 (softening point 95-105 ° C.). YS resin PX800 (softening point 75-85 ° C), YS resin PX1150N (softening point 110-120 ° C), YS resin TO125 (softening point 120-130 ° C), YS resin TO115 (softening point 110-120 ° C), YS Resin TO105 (softening point 100-110 ° C.) and YS resin TO85 (softening point 80-90 ° C.) (both manufactured by Yasuhara Chemical Co., Ltd.) are also preferably used for the adhesive.

  The content of the high softening point resin (G) in the case of including the high softening point resin (G) in the pressure-sensitive adhesive composition for an optical film of the present invention is not particularly limited, but a (meth) acrylate copolymer ( A) It is preferable that they are 0.1 mass part or more and 30 mass parts or less with respect to 100 mass parts, More preferably, they are 0.5 mass part or more and 25 mass parts or less, 1 mass part or more and 20 mass parts or less. It is more preferable that it is 2 parts by mass or more and 15 parts by mass or less. When the content is 0.1 parts by mass or more, it is preferable from the viewpoint of obtaining a softening effect during a durability test. Moreover, it is preferable from a viewpoint that generation | occurrence | production of curvature and a dent can be suppressed. On the other hand, when the content is 30 parts by mass or less, it is preferable from the viewpoint that deterioration of durability due to low molecular weight substances can be suppressed. Moreover, it is preferable from the viewpoint that durability can be ensured even in a severe environment such as a decrease in flexibility of the pressure-sensitive adhesive composition can be effectively suppressed even in a low temperature region of −25 ° C. or lower, and light leakage can be sufficiently suppressed.

  The softening point of the high softening point resin (G) is preferably 60 ° C. or higher and 200 ° C. or lower, but further has heat resistant holding power, adhesiveness, flexibility in a low temperature region such as −25 ° C., durability and reworkability. From the viewpoints of improvement in light emission, suppression of light leakage, and further suppression of warpage and dents, it is more preferably in the range of 70 ° C. or higher and 150 ° C. or lower, more preferably in the range of 80 ° C. or higher and 140 ° C. or lower, and particularly preferably 85 ° C. or higher. It is the range of 130 degrees C or less. In the present invention, as the softening point, a value measured by the method described in JIS K6863 (1994) (the dry bulb method described in the examples) is adopted.

<Other additive components>
The pressure-sensitive adhesive composition for an optical film of the present invention can contain a crosslinking accelerator, an anti-aging agent, a filler, a colorant (such as a pigment or a dye), an ultraviolet absorber, an antioxidant, a chain transfer agent, a plasticizer, if necessary. You may contain well-known additive components (other additive components), such as an agent, a softening agent, surfactant, an antistatic agent, in the range which does not impair the effect of this invention.

{Production (preparation) method of pressure-sensitive adhesive composition for optical film}
In the present invention, the pressure-sensitive adhesive composition for an optical film is not particularly limited. For example, the (meth) acrylate copolymer (A) and the isocyanate compound (B), and a crosslinking agent (C) that can be optionally contained, silane Coupling agent (D), silicate oligomer (E), peroxide (F), high softening point resin (G), (meth) acrylic (co) polymer (H), solvent, and other additives Can be prepared by mixing. In addition, about the mixing order of each said component, mixing temperature, etc., there is no restriction | limiting in particular, It can adjust suitably by those skilled in the art.

{Usage}
The above-mentioned pressure-sensitive adhesive composition for optical films of the present invention is suitable for various applications. For example, it is preferably used for an optical member such as an optical film. In particular, in recent years, it is preferably used for thin adhesive optical films used for large liquid crystal panels. As such an optical film, a polarizing plate, a retardation plate for preventing coloring, an optical compensation film such as a viewing angle expansion film for improving the viewing angle of a liquid crystal display, a brightness enhancement film for increasing the contrast of the display, Furthermore, what laminated | stacked these is mentioned.

  In the present invention, the form of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition for optical films, the form of the optical member in which the pressure-sensitive adhesive layer is formed on the optical film, the form in which the optical film is a polarizing plate, Alternatively, a mode in which the optical member is applied to an image display device such as a liquid crystal display device, an organic EL display device, a plasma display (PDP), a micro LED display, a curved display, or a flexible display can be provided. Each will be described below.

<Adhesive layer>
According to one form of this invention, the adhesive layer for optical films formed from the adhesive composition for optical films of this invention mentioned above is provided. According to the pressure-sensitive adhesive layer for an optical film of the present invention, both durability and reworkability in a harsh environment (high temperature, high humidity, heat shock) can be achieved, and light leakage can be sufficiently suppressed. Moreover, it has durability and reworkability even under harsh environments (high temperature, high humidity, heat shock), can sufficiently suppress light leakage, and can further suppress warpage and dents. In addition, according to the pressure-sensitive adhesive layer for an optical film of the present invention, while maintaining good reworkability that allows an optical film to be easily peeled off from a liquid crystal panel or the like without being left behind, contamination during re-peeling and severe conditions Peeling can be suppressed, and light leakage can be sufficiently suppressed. Furthermore, the solid content at the time of coating is high, the coating speed can be secured at a higher level than ever, and an adhesive optical film of good quality having excellent handling properties in the production process can be obtained.

  The thickness of the pressure-sensitive adhesive layer of the present invention (film thickness after drying) can be appropriately set by those skilled in the art depending on the application, but is preferably 1 μm or more and 200 μm or less, more preferably 3 μm or more and 75 μm or less, More preferably, they are 5 micrometers or more and 40 micrometers or less, Especially preferably, they are 7 micrometers or more and 35 micrometers or less, Most preferably, they are 10 micrometers or more and 30 micrometers or less. When the thickness is within the above range, it is preferable from the viewpoint that a good balance between durability and adhesive properties can be obtained. In addition to durability and reworkability, it is preferable from the viewpoint that warpage and dents can be suppressed.

  The gel fraction immediately after drying of the pressure-sensitive adhesive layer of the present invention is not particularly limited, but is preferably 95% or less from the viewpoint of punching or slitting. Moreover, it is preferably 40% or more and more preferably 65% or more from the viewpoint that there is no concern about dents, warpage or durability on the pressure-sensitive adhesive layer immediately after drying, and no aging treatment is required. The gel fraction can be adjusted by controlling the amount of the crosslinking agent and the amount of peroxide.

The intrinsic birefringence of the pressure-sensitive adhesive layer is not particularly limited, but is preferably −0.5 × 10 ⁻⁴ or more and 0 or less, more preferably −0.45 × 10 ⁻⁴ or more and −0.1 × 10 ^−4. Or less, more preferably −0.40 × 10 ⁻⁴ or more and −0.2 × 10 ⁻⁴ or less. When the intrinsic birefringence is within the above range, the total intrinsic birefringence including the optical film and the liquid crystal panel is close to 0, and light leakage is less likely to occur. The intrinsic birefringence can be easily controlled by those skilled in the art by adjusting the structure and ratio of the structural units of the (meth) acrylate copolymer (A).

  In this specification, the intrinsic birefringence adopts a value obtained on the basis of “Method for evaluating birefringence of adhesive” described in JP 2012-233901 A. In short, the intrinsic birefringence of the copolymer (Z) obtained by copolymerizing 90% by mass of the monomer (x) and 10% by mass of the monomer (y) is determined as follows. That is, first, the intrinsic birefringence (value is A) of the polymer (X) consisting only of the monomer (x) and the intrinsic birefringence (value is B) of the polymer (Y) consisting only of the monomer (y). Ask). Then, each intrinsic birefringence value is weighted by the proportion of the monomer used, and the value obtained by adding together (the value is C) is defined as the intrinsic birefringence of the copolymer (Z). In this case, the intrinsic birefringence C of the copolymer (Z) is C = A × 0.9 + B × 0.1.

[Method for producing pressure-sensitive adhesive layer]
The pressure-sensitive adhesive layer according to the present invention is not particularly limited. For example, the above-described pressure-sensitive adhesive composition for an optical film according to the present invention is applied on a release-treated release sheet, and then subjected to a heat treatment to cause a crosslinking reaction. Can be manufactured. Such heat treatment can not only dry and remove the solvent in the coating film obtained by coating, but can also achieve the purpose of crosslinking reaction of the above-mentioned pressure-sensitive adhesive composition for optical films. Moreover, the temperature of heat processing becomes like this. Preferably it is 40 to 150 degreeC, More preferably, it is 50 to 130 degreeC, More preferably, it is 80 to 120 degreeC. By setting the temperature of the heat treatment within the above range, a pressure-sensitive adhesive layer having excellent pressure-sensitive adhesive properties can be obtained. The heat treatment time can be appropriately set, but is preferably 5 seconds or more and 20 minutes or less, more preferably 5 seconds or more and 10 minutes or less, and particularly preferably 10 seconds or more and 5 minutes or less.

  Moreover, it does not restrict | limit especially as a means of heat processing, Various well-known methods are used. For example, a parallel drying method that blows hot air in the same direction up and down in the film conveyance direction, a counter drying method that blows hot air in the film conveyance direction in different directions up and down, a float drying method that blows hot air directly from the top and bottom of the film, etc. A method is mentioned.

  When the pressure-sensitive adhesive composition is used for an optical film, the pressure-sensitive adhesive composition may be directly coated on the optical film to form a pressure-sensitive adhesive layer, but the pressure-sensitive adhesive composition is formed on a film having releasability. It is desirable to apply the product to form an adhesive layer and then transfer it to various optical films. Moreover, the film having the release property with the pressure-sensitive adhesive layer produced in this way can also be wound together in the production process to form a roll, and can be cut and processed as necessary to obtain various After being attached to an optical film or a liquid crystal panel, the film having the releasability can be removed and used. Furthermore, until the pressure-sensitive adhesive layer is put to practical use, the film having releasability can also serve to protect the pressure-sensitive adhesive layer. In this specification, such a film having releasability is also referred to as a release sheet (separator).

  Examples of the constituent material of the release sheet include plastic films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester films, porous materials such as paper, cloth, and nonwoven fabric, nets, foamed sheets, metal foils, and laminates thereof. However, a plastic film is preferably used from the viewpoint of excellent surface smoothness.

  Further, the thickness of the release sheet is usually 5 μm or more and 200 μm or less, preferably about 5 μm or more and 100 μm or less.

  Furthermore, for release sheets, silicone-type, fluorine-type, long-chain alkyl-type or fatty acid amide-type release agents, release treatment with silica powder and antifouling treatment, coating type, kneading type, if necessary Further, an antistatic treatment such as a vapor deposition type can be further performed. In particular, from the viewpoint of further improving the releasability from the pressure-sensitive adhesive layer, it is preferable to perform a release treatment such as silicone treatment, long-chain alkyl treatment, and fluorine treatment on the surface of the release sheet.

  The application method for applying the pressure-sensitive adhesive composition for an optical film of the present invention onto a release sheet subjected to a release treatment is not particularly limited, and various known methods can be used. For example, roll coat, kiss roll coat, gravure coat, reverse coat, roll brush, spray coat, dip roll coat, bar coat, knife coat, air knife coat, curtain coat, lip coat, extrusion coat method by die coater, etc. A method is mentioned.

<Optical member>
According to one form of this invention, the optical member which has the adhesive layer for optical films mentioned above and the optical film provided in one surface of the said adhesive layer is provided. According to the optical film of the present invention, both durability and reworkability in a harsh environment (high temperature, high humidity, heat shock) can be achieved, and light leakage can be sufficiently suppressed. Further, it has durability and reworkability even in a harsh environment (high temperature, high humidity, heat shock), can sufficiently suppress light leakage, and can further suppress warpage and dents. Further, according to the optical film of the present invention, while maintaining good reworkability that allows the optical film to be easily peeled off from the liquid crystal panel or the like without being left behind, contamination during re-peeling or peeling under severe conditions is prevented. While being able to suppress, light leakage can fully be suppressed. Furthermore, the solid content at the time of coating is high, the coating speed can be secured at a higher level than ever, and an adhesive optical film of good quality having excellent handling properties in the production process can be provided.

  In addition, the optical member of the present invention has a glass or optical film (second optical film) on the surface of the pressure-sensitive adhesive layer of the present invention opposite to the surface provided with the optical film (first optical film). Can further be included. Here, the “first optical film” and the “second optical film” may be films having the same configuration (material, function, etc.), and have different configurations (material, function, etc.). It may be a film. Moreover, in this invention, the form whose 1st optical film (or 2nd optical film) is a polarizing plate is also provided.

  In the present invention, the above-mentioned pressure-sensitive adhesive composition may be used by directly applying to one or both sides of an optical film to form a pressure-sensitive adhesive layer. It is desirable to use it by forming it and transferring it to one or both sides of the optical film. Before the transfer, the surface of the optical film may be subjected to a ground treatment such as a corona treatment, a plasma treatment, or an easy adhesion treatment layer, or an antistatic layer, depending on the material. Moreover, you may perform an easily bonding process also on the surface of an adhesive layer. From the viewpoint of firmly bonding the optical film and the pressure-sensitive adhesive layer, it is preferable to have an easy adhesion treatment layer between the optical film and the pressure-sensitive adhesive layer for optical films of the present invention.

<Easy adhesion treatment layer (easy adhesion layer)>
It is preferable that the optical member of the present invention further includes at least one easy adhesion treatment layer between the optical film and the optical film pressure-sensitive adhesive layer. Thereby, it is preferable from a viewpoint that an optical film and an adhesive layer can be adhere | attached more firmly.

  As a more preferred embodiment, the optical member of the present invention has a first easy-adhesion treatment layer on the surface of the optical film facing the pressure-sensitive adhesive layer for the optical film, and the pressure-sensitive adhesive for the optical film. The layer has a second easy adhesion treatment layer on the surface facing the optical film. Thus, in an optical member, the structure which has both the 1st and 2nd easily-adhesion process layer is preferable from a viewpoint that an optical film and an adhesive layer can be adhere | attached more firmly. Note that the “first easy-adhesion treatment layer” and the “second easy-adhesion treatment layer” here may be easy-adhesion treatment layers having the same configuration (materials, etc.), and different configurations (materials). Etc.) may be used.

  As the easy-adhesion treatment layer, the surface of a member that comes into contact with the pressure-sensitive adhesive layer, such as corona treatment or plasma treatment, may be treated, or another member such as a primer layer may be treated with the pressure-sensitive adhesive layer. It may be provided on the surface.

  In the present invention, the material constituting the primer layer is preferably one that forms a film that has good adhesion to the member that contacts the primer layer and is excellent in cohesion. For example, various polymers, metal oxide sols, silica sols and the like are used, and polymers are preferably used. The primer layer may have an antistatic function.

  Examples of polymers constituting the primer layer include oxazoline group-containing polymers, polyurethane resins, polyester resins, and polymers containing amino groups in the molecule. Among these, an oxazoline group-containing polymer is more preferably used.

  Commercially available products can be used as the oxazoline group-containing polymer. Examples thereof include, but are not limited to, EPOCROS (registered trademark) series (for example, EPOCROSS (registered trademark) WS700) manufactured by Nippon Shokubai Co., Ltd. In addition, as the polyurethane resin, the polyester resin, the polymers containing an amino group in the molecule, those disclosed in paragraphs “0107” to “0113” of JP2011-105918A can be appropriately employed.

  The thickness of the primer layer is about 10 nm to 5000 nm, preferably 50 nm to 500 nm. Within the above range, optical properties can be maintained while exhibiting sufficient strength and adhesiveness.

  The method for forming the primer layer is not particularly limited, and the primer layer can be formed by applying the primer layer raw material (primer) using a coating method such as a coating method, a dipping method, or a spray method, and drying. .

<Optical film>
In the present invention, the optical film (first optical film or second optical film) is an optical film such as a polarizing plate, a retardation plate for preventing coloring, and a viewing angle widening film for improving the viewing angle of a liquid crystal display. Examples include, but are not limited to, a compensation film, a brightness enhancement film for increasing the contrast of the display, and those in which these are laminated. In particular, from the viewpoint of applying a pressure-sensitive adhesive layer formed using the pressure-sensitive adhesive composition for optical films of the present invention, an optical member using a polarizing plate for the optical film is one of the preferred ones. An optical member using a polarizing plate for the optical film is excellent in durability under a high temperature environment. In addition, while maintaining good reworkability that allows the polarizing plate to be easily peeled off from the liquid crystal panel of the optical member and the like, it is possible to suppress contamination during re-peeling and peeling under harsh conditions, and light leakage Can also be sufficiently suppressed. Further, the warpage of the polarizing plate (optical film) on the outermost surface of the polarizing plate with the pressure-sensitive adhesive layer and the occurrence of dents can be suppressed. In addition, even if the solid content (or viscosity of the composition) at the time of application of the pressure-sensitive adhesive composition to the polarizing plate is high, the coating speed can be secured at a higher level than before, and the handling process is excellent. It is excellent in that an optical member using a polarizing plate with good quality can be provided.

<Polarizing plate>
In the present invention, a polarizing plate suitable as an optical film is produced by pasting a protective film and a polarizer together with an adhesive by using a conventionally known method and curing by heat drying or ultraviolet rays, an electron beam, or the like. obtain. The applied adhesive exhibits adhesiveness by drying or curing with ultraviolet rays, electron beams or the like, and constitutes an adhesive layer.

  There is no restriction | limiting in particular as a polarizer, A conventionally well-known thing can be used. For example, dichroic materials such as iodine and dichroic dyes are adsorbed on hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymer partially saponified films. And polyene-based oriented films such as a uniaxially stretched product, a polyvinyl alcohol dehydrated product and a polyvinyl chloride dehydrochlorinated product.

  Among these, a polarizer produced by dyeing a polyvinyl alcohol film having an average polymerization degree of 2000 or more and 2800 or less and a saponification degree of 90 mol% or more and 100 mol% or less with iodine and uniaxially stretching 3 to 8 times is particularly preferable. . More specifically, such a polarizer is obtained by, for example, immersing and stretching a polyvinyl alcohol film by immersing it in an aqueous solution of iodine.

  As a method for immersing in an aqueous solution of iodine, for example, it is preferable to immerse in an aqueous solution containing 0.1 to 10% by mass of iodine and / or potassium iodide. If necessary, it may be immersed in an aqueous solution of boric acid or potassium iodide at 50 ° C. or higher and 70 ° C. or lower, or immersed in water at 25 ° C. or higher and 35 ° C. or lower in order to prevent uneven washing or dyeing. Also good. Stretching may be performed after dyeing with iodine, may be stretched while dyeing, or may be dyed with iodine after stretching. After dyeing and stretching, it may be washed with water and dried at 35 ° C. or more and 55 ° C. or less for 1 minute or more and 10 minutes or less. A wide variety of such polarizers are commercially available.

  The thickness of the polarizer is not particularly limited, but is generally 5 μm or more and 80 μm or less.

  In the present invention, from the viewpoint that higher durability is required as an optical film, a polarizing plate in which one or both sides are protected as an optical film is preferable. The protection method is not particularly limited, and a known method such as attaching a protective film can be appropriately employed.

  As the protective film, a material excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy and the like is preferable. For example, acrylic resins, cellulose resins such as triacetyl cellulose, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefins And (meth) acrylic resins such as polymethyl methacrylate, cyclic polyolefin resins (norbornene resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, epoxy resins, and mixtures thereof.

  A transparent protective film is bonded to one side of the polarizer with an adhesive. On the other side, a (meth) acrylic, urethane-based, acrylic-urethane-based, epoxy-based transparent protective film or protective layer Further, a silicone-based thermosetting resin or an ultraviolet curable resin can be used.

  The thickness of the polarizing plate is not particularly limited, but is generally 20 μm or more and 200 μm or less. In the present invention, from the viewpoint of thinning, it is preferably 100 μm or less, more preferably 75 μm or less, and particularly preferably 50 μm or less. Such a thin polarizing plate is preferable from the viewpoint of more remarkably expressing the effect of the pressure-sensitive adhesive composition of the present invention.

  The manufacturing method of a polarizing plate is not specifically limited, For example, after apply | coating an adhesive agent, it can carry out by bonding together a polarizer and a protective film with a roll laminator etc. After bonding, a curing step may be performed as appropriate by drying or ultraviolet rays, an electron beam or the like. Moreover, when apply | coating an adhesive agent, you may apply | coat to any of a protective film and a polarizer, and may apply | coat to both. The adhesive is preferably applied so that the thickness of the adhesive layer after drying is 10 nm or more and 10 μm or less. Moreover, it does not specifically limit as an adhesive agent, According to the material of a polarizer, it can employ | adopt suitably from well-known things. For example, when a polyvinyl alcohol film is used as the polarizer, an acrylic, epoxy, or acryl-epoxy system can be used as the polyvinyl alcohol adhesive or the ultraviolet curable adhesive. The thickness of the adhesive layer is preferably 10 nm or more and 200 nm or less for a polyvinyl alcohol-based adhesive, and 0 for an ultraviolet curable adhesive, in order to obtain a uniform in-plane thickness and sufficient adhesive strength. It is preferably 2 μm or more and 10 μm or less.

  In the present invention, an adhesive polarizing plate in which an adhesive layer is formed can also be provided. In addition, since it is the same as that of the case of the optical film which has an adhesive layer mentioned above about the structure, manufacture, etc. of an adhesive type polarizing plate, description is abbreviate | omitted here.

<Image display device>
The present invention also provides an image display device using at least one of the optical members described above. According to the image display device of the present invention, it has durability even in a harsh environment (high temperature, high humidity, heat shock), and can suppress warpage and dents of the optical member, particularly the outermost optical film. In addition, according to the image display device of the present invention, while maintaining good reworkability that allows the optical film to be easily peeled off from an optical member such as a liquid crystal panel, an organic EL panel, a PDP panel, or a micro LED panel without any adhesive residue. In addition to suppressing contamination during re-peeling and peeling under severe conditions, light leakage can also be sufficiently suppressed. Furthermore, it is possible to provide an image display device including an optical member using an optical film that has a high solid content at the time of coating and can secure a coating speed higher than ever and has excellent handling properties in the manufacturing process.

  The image display device is not particularly limited, and examples thereof include a liquid crystal display device, an organic EL display device, a plasma display (PDP), and a micro LED display. In addition, a thin image display device is preferably applied from the viewpoint of more remarkably expressing the effect of the pressure-sensitive adhesive composition of the present invention.

  The present invention will be described in more detail with reference to the following examples and comparative examples, but the technical scope of the present invention is not limited only to the following examples.

  In the following operations, unless otherwise specified, measurements such as operation and physical properties are performed under the conditions of 23 ° C. and relative humidity 55% RH.

[Preparation of Production Example 1 (Meth) acrylate Copolymer (A1)]
In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a cooler, 13% by mass of benzyl acrylate (manufactured by Hitachi Chemical Co., Ltd.), 70% by mass of n-butyl acrylate (manufactured by Nippon Shokubai Co., Ltd.) , 16% by mass of methyl acrylate (manufactured by Nippon Shokubai Co., Ltd.), 1% by mass of 4-hydroxybutyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.), and 2,2′-azobisisobutyronitrile (as a polymerization initiator) 0.1% by mass of Wako Pure Chemical Industries, Ltd.) was charged together with 100% by mass of ethyl acetate, and nitrogen gas was introduced while gently stirring. After substituting with nitrogen gas, the liquid temperature in the flask was controlled at around 55 ° C., and the polymerization reaction was carried out for 5 hours. A (meth) acrylate copolymer having a weight average molecular weight (Mw) of 1.9 million and Mw / Mn = 1.6 A solution of (A1) was prepared.

[Preparation of Production Examples 2 to 13 (meth) acrylate copolymers (A2) to (A13)]
Except having changed the kind of each monomer which forms a (meth) acrylate copolymer, and its composition ratio (blending amount) as shown in following Table 1, operation similar to manufacture example 1 was performed, and (meth) Solutions of acrylate copolymers (A2) to (A13) were prepared. Table 1 also shows the values of the weight average molecular weight (Mw) and the degree of dispersion (Mw / Mn).

  In addition, the measurement of the weight average molecular weight (Mw), number average molecular weight (Mn), and dispersity (Mw / Mn) in each manufacture example 1-13 mentioned above was performed in accordance with the following method.

[Measurement of weight average molecular weight (Mw), number average molecular weight (Mn), and dispersity (Mw / Mn)]
The weight average molecular weight (Mw), number average molecular weight (Mn), and dispersity (Mw / Mn) of each (meth) acrylate copolymer prepared in each of Production Examples 1 to 13 described above are GPC (gel permeation). -Chromatography) (see below for measurement conditions).

・ Analyzer: HLC-8120GPC, manufactured by Tosoh Corporation
Column: manufactured by Tosoh Corporation, G7000H _XL + GMH _XL + GMH _XL
・ Column size: 7.8mmφ × 30cm each 90cm in total
-Column temperature: 40 ° C
・ Flow rate: 0.8ml / min
・ Injection volume: 100 μl
・ Eluent: Tetrahydrofuran ・ Detector: Differential refractometer (RI)
Standard sample: polystyrene.

  The types and compositions of the monomers of Production Examples 1 to 13 are shown in Table 1 below. The blank in Table 1 indicates that the monomer was not used.

[Measurement of NCO% of isocyanate compound (B)]
The measuring method of NCO% of the isocyanate compound (B) used in the following examples and comparative examples is as follows.

  Precisely weigh the sample in a stoppered Erlenmeyer flask and add 25 ml of chlorobenzene and 10 ml of a mixture of di-n-butylamine / orthodichlorobenzene (weight ratio: di-n-butylamine / orthodichlorobenzene = 1 / 24.8). And dissolved. To this, 80 g of methanol and bromophenol blue reagent were added as indicators and titrated with a 0.1N alcoholic hydrochloric acid solution. Titration was continued until the solution was yellowish green and held for 30 seconds. NCO% was calculated | required by following Formula. The results are shown in Table 2 and Table 4.

[Measurement of weight average molecular weight of silicate oligomer (E)]
The weight average molecular weight of the silicate oligomer (E) used in the following examples and comparative examples was measured by GPC (gel permeation chromatography) (see below for measurement conditions). The results are shown in Table 2 and Table 4.

・ Analyzer: HLC-8120GPC, manufactured by Tosoh Corporation
Column: TSKgel SuperHZM-H / HZ4000 / HZ2000
Column size: 6.0 mmI. D. × 150mm
-Column temperature: 40 ° C
・ Flow rate: 0.6ml / min
・ Injection volume: 20 μl
・ Eluent: Tetrahydrofuran ・ Detector: Differential refractometer (RI)
Standard sample: polystyrene.

[How to determine intrinsic birefringence of adhesive layer]
The method for obtaining the intrinsic birefringence of the pressure-sensitive adhesive layers formed in the following Examples and Comparative Examples is as follows.

  The intrinsic birefringence of the pressure-sensitive adhesive layer was calculated based on JP2012-233901A. The results are shown in Table 3 and Table 5. In addition, the following measured values were used as the value of the intrinsic birefringence of the polymer composed of a single monomer.

Poly n-butyl acrylate: −0.54 × 10 ⁻⁴
・ Polymethyl acrylate: −1.06 × 10 ⁻⁴
-Polymethylmethacrylate: -1.06 × 10 ^-4
Polybenzyl acrylate: 2.16 × 10 ⁻⁴
Polyphenoxyethyl acrylate: 1.98 × 10 ⁻⁴
Poly-4-hydroxybutyl acrylate: −0.54 × 10 ⁻⁴
-Polyacrylic acid: -0.46 * 10 < ^-4 >.

<< Examples and Comparative Examples Using the (Meth) acrylate Copolymer (A) of the First Embodiment >>
<Example 1>
[Preparation of pressure-sensitive adhesive composition for optical film]
Isocyanate with respect to the solid content of 100% (w / w) of the (meth) acrylate copolymer (A1) solution obtained in Production Example 1 (that is, 100 parts by weight of the (meth) acrylate copolymer (A1)). Samprene (registered trademark) P-663L as a compound (B) (manufactured by Sanyo Chemical Industries, Ltd., NCO% = 2.9%, number average molecular weight Mn = 2000) 0.1 part by mass, as a crosslinking agent (C) Isocyanate crosslinker Takenate (registered trademark) D-110N (75% ethyl acetate solution of trimethylolpropane adduct of xylylene diisocyanate, number of isocyanate groups in one molecule: 3, Mitsui Chemicals, number average molecular weight Mn = 700 ) 0.1 parts by mass (in terms of active ingredient), silane coupling agent (trade name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd., 3-glycidoxy Propyl trimethoxysilane) by blending 0.1 parts by mass, the optical film pressure-sensitive adhesive composition of Example 1 (solid content 15 wt%, the remainder solvent) was prepared.

(Formation of adhesive layer)
After drying the pressure-sensitive adhesive composition for optical film obtained above on one side of a 38 μm-thick polyethylene terephthalate (PET) film (Mitsubishi Resin Co., Ltd., MRF38, no oligomer prevention layer) subjected to silicone treatment The pressure-sensitive adhesive layer was applied to a thickness of 20 μm and heat-treated at 110 ° C. for 2 minutes to form the pressure-sensitive adhesive layer of Example 1. The heat treatment was performed by a float drying method in which hot air was blown directly from above and below the film.

(Production of optical member)
(Production of single-sided protective polarizing plate)
A single-sided protective polarizing plate was produced as an optical film by the following steps.

  A polyvinyl alcohol film having a thickness of 20 μm was stretched up to 3 times while being dyed in an iodine solution having a concentration of 0.3% by mass at 30 ° C. between rolls having different speed ratios. Thereafter, the film stretched up to 3 times is stretched until the total stretch ratio becomes 6 times while being immersed in an aqueous solution containing 4% by weight boric acid at 10% by weight and 10% by weight potassium iodide for 0.5 minutes. did. Next, the film stretched up to 6 times was washed by immersing it in an aqueous solution containing 1.5% by weight potassium iodide at 30 ° C. for 10 seconds, followed by drying at 50 ° C. for 4 minutes to obtain a polarizer. It was. An acrylic film (lactone-modified acrylic resin film; protective film) having a thickness of 20 μm is bonded to one side of the polarizer with a polyvinyl alcohol adhesive, and a single-side protective thin polarizing plate having a total thickness of 27 μm (simply single-side protection) (Also referred to as a polarizing plate).

(Preparation of single-sided protective polarizing plate with adhesive layer)
Corona treatment is carried out with a corona discharge of 80 [W · min / m ² ] on the polarizer side (the side opposite to the protective film side) that forms the pressure-sensitive adhesive layer of the single-sided protective polarizing plate obtained above. An adhesion treatment layer was formed. Next, the PET film (with silicone treatment) on which the pressure-sensitive adhesive layer was formed was transferred so that the easy-adhesion treatment layer of the polarizing plate was in contact, and the optical member of Example 1, that is, the single-sided protective polarized light with the pressure-sensitive adhesive layer A plate was made.

<Examples 2-57 and Comparative Examples 1-3>
As shown in Table 2 below, the (meth) acrylate copolymer (A), the isocyanate compound (B), and the crosslinking agent (C) as necessary, which constitute the optical film pressure-sensitive adhesive composition, silane coupling Type and addition amount (blending amount) of agent (D), silicate oligomer (E), peroxide (F) and high softening point resin (G), temperature and time of heat treatment when forming the adhesive layer Except having changed, it carried out similarly to operation of Example 1, and produced the single-sided protective polarizing plate with an adhesive layer corresponding to each of Examples 2-57 and Comparative Examples 1-3.

In Table 2 above,
1. The blending amount (parts by mass) of the components (B) to (G) represents the blending amount when the (meth) acrylate copolymer (A) is 100 parts by mass;
2. “-” In the table indicates that such a component is not blended;
3. “SAMPLEN P-663L”, “SAMPLEN P-664”, “SAMPLEN P-665”, “SAMPLEN P-6090”, “SAMPLEN P-7315”, “SAMPLEN P-870” and “SAMPLEN C-810” All are made by Sanyo Chemical Industries;
4). “V-05”: a carbodiimide-based crosslinking agent, a product (Carbodilite (registered trademark) V-05) manufactured by Nisshinbo Chemical Co., Ltd .:
5. “WS-500”: an oxazoline-based crosslinking agent, a product (Epocross (registered trademark) WS-500) manufactured by Nippon Shokubai Co., Ltd .:
6). “Tetrad-X”: an epoxy-based crosslinking agent, which is a product (trade name: TETRAD-X, N, N, N ′, N′-tetraglycidyl-m-xylenediamine) manufactured by Mitsubishi Gas Chemical Co., Inc .;
7). “PZ-33”: an aziridine-based crosslinking agent, a product manufactured by Nippon Shokubai Co., Ltd. (Chemite (registered trademark) PZ-33, 2,2-bishydroxymethylbutanol-tris [3- (1-aziridinyl) propionate) Is
8). “Methyl silicate 53A”: a product (product name: methyl silicate 53A) manufactured by Colcoat Co., Ltd .:
9. “D-110N”: Takenate (registered trademark) D-110N (manufactured by Mitsui Chemicals, Ltd.) 75 wt% ethyl acetate solution of trimethylolpropane adduct of xylylene diisocyanate, number of isocyanate groups in one molecule: 3, number average molecular weight Mn = 700);
10. "CL": Tosoh Corporation product (Coronate (registered trademark) L, TDI trimethylolpropane adduct 75 wt% ethyl acetate solution, number of isocyanate groups in one molecule: 3, number average molecular weight Mn = 670 );
11. “Coronate 2094”: a product manufactured by Tosoh Corporation (Coronate (registered trademark) 2094, HDI and hydrogenated bisphenol A modified product, number average molecular weight Mn = 570);
12 “Pine Crystal KE-100”: Softening point 95-105 ° C. (ring and ball method) Ultra-light rosin derivative [Pine Crystal (registered trademark)] manufactured by Arakawa Chemical Industries, Ltd .;
13. "Superester A-75": Softening point 70-80 ° C (ring and ball method) Special rosin ester [Superester] manufactured by Arakawa Chemical Industries, Ltd .;
14 “Tamanol 460”: softening point 182-192 ° C. (ring and ball method) Rosin-modified phenol resin [Tamanol (registered trademark)] manufactured by Arakawa Chemical Industries, Ltd.

{Evaluation}
The following evaluation was performed with respect to the single-sided protective polarizing plate (sample) with each adhesive layer which is an optical member produced in Examples 1 to 57 and Comparative Examples 1 to 3. Each evaluation result is shown in Table 3.

<Durability>
The optical members prepared in Examples 1 to 57 and Comparative Examples 1 to 3 were cut into a 37-inch size to obtain a sample, which was pasted on a non-alkali glass (Corning Corp., Eagle XG) with a thickness of 0.7 mm using a laminator. I wore it. Subsequently, the sample was autoclaved at 50 ° C. and 0.5 MPa for 15 minutes to completely adhere the sample to the acrylic-free glass. The samples subjected to such treatment were subjected to the following durability tests (1) to (3), and after each test, the appearance between the polarizing plate and the glass was visually evaluated according to the following criteria.

(1) Treated at 105 ° C. for 500 hours (heating test)
(2) Treated in an atmosphere of 60 ° C. and relative humidity of 95% RH for 500 hours (humidification test)
(3) After being left for 30 minutes in an environment at 85 ° C. and then left for 30 minutes in an environment at −40 ° C., one cycle was treated for 300 cycles (300 hours) for one hour (heat shock (HS) test) ).

-Visual evaluation-
◎: No change in appearance such as foaming, peeling, no floating ○: Slightly peeling or foaming at the end, but no problem in practical use △: Peeling or foaming at the end, but special There is no practical problem if it is not a proper use.

<Light leakage>
Each of the optical members produced in Examples 1 to 57 and Comparative Examples 1 to 3 was cut out as a sample so that the upper and lower polarizing plates were orthogonal to a size of 420 mm long × 320 mm wide. This sample was bonded with a laminator so as to be crossed Nicol on both surfaces of a non-alkali glass plate (Corning, Eagle XG) having a thickness of 0.7 mm. Subsequently, the autoclave process was performed for 15 minutes at 50 degreeC and 5 atm, and the process for 48 hours was performed on the conditions of 105 degreeC after that. The heated sample was placed on a 10,000 candela backlight, and light leakage was visually evaluated according to the following criteria.

-Visual evaluation-
A: There is no occurrence of corner unevenness and there is no problem in practical use. ○: A slight amount of corner unevenness occurs but it does not appear in the display area, so there is no problem in practical use. Although it appears slightly, there is no problem in practical use. X: Corner unevenness occurs and appears in the display area, which is problematic in practical use.

<Reworkability>
Samples obtained by cutting the optical members produced in Examples 1 to 57 and Comparative Examples 1 to 3 into a width of 25 mm × a length of 100 mm are Sample 1, and those obtained by cutting into a length of 420 mm × width of 320 mm are Sample 2 (prepared by 3 sheets). did. Samples 1 and 2 were each attached to a non-alkali glass plate (Corning Corp., Eagle XG) with a thickness of 0.7 mm using a laminator, and then autoclaved at 50 ° C. and 5 atm for 15 minutes to completely Close contact (initial). Thereafter, heat treatment was performed for 48 hours under a dry condition of 50 ° C. (after heating).

  The adhesive strength of Sample 1 was measured. The adhesive strength was measured according to JIS Z0237 (Peeling angle 180 °, peeling speed 300 mm / min, using a tensile tester (Tensilon Universal Material Tester STA-1150, manufactured by Orientec Co., Ltd.) under the conditions of 23 ° C. and 50% RH. In accordance with the adhesive tape and adhesive sheet test method of 2009), the adhesive strength (N / 25 mm) when peeling sample 1 was determined.

  Moreover, about the said sample 2 (3 sheets), the sample was peeled off from the alkali free glass plate by human hand, and rework property was evaluated on the following reference | standard (actual rework property).

-Evaluation-
◎: All three sheets can be peeled off satisfactorily without any adhesive residue or film. ○: Some of the three sheets were broken, but were peeled off by peeling again. △: All three sheets were broken, but again X: Peeled off in all three sheets, or the film was broken and could not be peeled, no matter how many times it was peeled off.

  As described above, the results of the adhesive strength and the actual reworkability were comprehensively determined for the reworkability of the samples of Examples 1 to 57 and Comparative Examples 1 to 3.

  As is clear from Table 3, the single-sided protective polarizing plates with pressure-sensitive adhesive layers (Examples 1 to 57) using the pressure-sensitive adhesive composition for optical films of the present invention were all in harsh environments (high temperature, high It was found that both durability and reworkability in humidity and heat shock can be achieved, and light leakage can be suppressed. On the other hand, it turns out that none of the single-sided protective polarizing plates with pressure-sensitive adhesive layers of Comparative Examples 1 to 3 can achieve both durability and reworkability in harsh environments (high temperature, high humidity, heat shock). It was. In addition, it was found that there are some (Comparative Example 2) that cannot suppress light leakage.

<< Example and Comparative Example Using (Meth) acrylate Copolymer (A) of Second Embodiment >>
<Example 58>
[Preparation of pressure-sensitive adhesive composition for optical film]
Solid content 100% (w / w) of the (meth) acrylate copolymer (A8) solution obtained in Production Example 8 shown in Table 1 above (that is, 100 parts by weight of (meth) acrylate copolymer (A8)) , Samprene (registered trademark) P-663L (manufactured by Sanyo Chemical Industries, Ltd., NCO% = 2.9%, number average molecular weight Mn = 2000) 0.5 part by mass as an isocyanate compound (B), crosslinking agent (C) Isocyanate crosslinker Takenate (registered trademark) D-110N (75% ethyl acetate solution of trimethylolpropane adduct of xylylene diisocyanate, number of isocyanate groups in one molecule: 3, Mitsui Chemicals, Inc., number Average molecular weight Mn = 700) 0.2 parts by mass (in terms of active ingredient), silane coupling agent (trade name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd., 3 By blending glycidoxypropyltrimethoxysilane) 0.1 parts by mass, adhesive composition for optical films of Example 58 (solid content 25 wt%, the remainder solvent) was prepared.

(Formation of adhesive layer)
After drying the pressure-sensitive adhesive composition for optical film obtained above on one side of a 38 μm-thick polyethylene terephthalate (PET) film (Mitsubishi Resin Co., Ltd., MRF38, no oligomer prevention layer) subjected to silicone treatment The pressure-sensitive adhesive layer was applied to a thickness of 20 μm, and heat-treated at 110 ° C. for 2 minutes to form a pressure-sensitive adhesive layer of Example 47. The heat treatment was performed by a float drying method in which hot air was blown directly from above and below the film.

(Production of optical member)
(Production of double-sided protective polarizing plate)
A double-sided protective polarizing plate was produced as an optical film by the following steps.

  A polyvinyl alcohol film having a thickness of 60 μm was stretched up to 3 times while being dyed in an iodine solution having a concentration of 0.3% by mass at 30 ° C. between rolls having different speed ratios. Thereafter, the film stretched up to 3 times is stretched until the total stretch ratio becomes 6 times while being immersed in an aqueous solution containing 4% by weight boric acid at 10% by weight and 10% by weight potassium iodide for 0.5 minutes. did. Next, the film stretched up to 6 times was washed by immersing it in an aqueous solution containing 1.5% by weight potassium iodide at 30 ° C. for 10 seconds, followed by drying at 50 ° C. for 4 minutes to obtain a polarizer. It was. A 40 μm thick triacetyl cellulose (TAC) film (protective film) is applied to one side of the polarizer, and a 80 μm thick PET film (Cosmo Shine (registered trademark) manufactured by Toyobo Co., Ltd. A refraction type (SRF) PET film (protective film) was bonded with a polyvinyl alcohol-based adhesive to prepare a double-sided protective thin polarizing plate (also simply referred to as a double-sided protective polarizing plate) having a total thickness of 143 μm.

(Preparation of double-sided protective polarizing plate with adhesive layer)
On the TAC film (protective film) side that forms the pressure-sensitive adhesive layer of the double-sided protective polarizing plate obtained above, corona treatment is performed with a corona discharge amount of 80 [W · min / m ² ] to form an easy adhesion treatment layer. did. Next, the PET film (with silicone treatment) on which the pressure-sensitive adhesive layer was formed was transferred so that the easy adhesion treatment layer of the double-sided protective polarizing plate was in contact, and the optical member of Example 58, that is, both surfaces with the pressure-sensitive adhesive layer A protective polarizing plate was produced.

<Examples 59 to 82 and Comparative Examples 4 to 6>
As shown in Table 4 below, the (meth) acrylate copolymer (A), the isocyanate compound (B), and the crosslinking agent (C) as required, which constitute the pressure-sensitive adhesive composition for an optical film, silane coupling Kinds and addition amounts (blending amounts) of the agent (D) and the silicate oligomer (E), peroxide (F), high softening point resin (G) and (meth) acrylic (co) polymer (H), Coating liquid solid mass% (solid content of the pressure-sensitive adhesive composition for optical film), except that the temperature and time of the heat treatment when forming the pressure-sensitive adhesive layer were changed in the same manner as in the operation of Example 58, Double-sided protective polarizing plates with pressure-sensitive adhesive layers corresponding to Examples 59 to 82 and Comparative Examples 4 to 6 were prepared.

In Table 4 above,
1. The blending amount (parts by mass) of the components (B) to (H) represents the blending amount when the (meth) acrylate copolymer (A) is 100 parts by mass;
2. “-” In the table indicates that such a component is not blended;
3. For details of the trade names of each commercial product shown in the “type” column of each component, see Note 1 in Table 2. -14. As described in;
4). Notes to Table 2 -14. Those not described in Section 4.1 are shown in 4.1 below;
4.1. “Alfon (registered trademark) UH-2170”: Solvent-free styrene acrylic polymer, weight average molecular weight (Mw) 14,000, glass transition temperature (Tg) 60 ° C., manufactured by Toagosei Co., Ltd.

{Evaluation}
Adhesive composition (adhesive coating liquid) (sample) prepared in Examples 58 to 82 and Comparative Examples 4 to 6 and a double-sided protective polarizing plate with each adhesive layer as an optical member using the same (sample) The following evaluation was performed on the sample. The respective evaluation results are shown in Table 5.

(Evaluation of properties of adhesive composition)
The following coating liquid solid content and viscosity were measured as evaluation of the characteristic of the acrylic adhesive composition (adhesive coating liquid) produced in said Examples 58-82 and Comparative Examples 4-6.

<Solid content>
What expressed the volatile residue at the time of heat-drying the acrylic adhesive composition (adhesive coating liquid) produced in said Example 58-82 and Comparative Examples 4-6 at 150 degreeC for 30 minutes "coating. Liquid solid content (mass%) ".

<Viscosity>
The acrylic pressure-sensitive adhesive compositions (pressure-sensitive adhesive coating solutions) prepared in Examples 58 to 82 and Comparative Examples 4 to 6 were rotated at a rotation speed of 20 rpm with a Brookfield viscometer (B-type viscometer). The value after 1 minute was read as the viscosity value.

(Characteristic evaluation of optical members)
<Warpage amount>
The optical member (double-sided protective polarizing plate with pressure-sensitive adhesive layer) prepared in Examples 58 to 82 and Comparative Examples 4 to 6 was used as a cut sample having a size of 100 mm in length and 50 mm in width. This sample was stuck to a non-alkali glass (Corning Corp., Eagle XG) having a length of 75 mm × width of 150 mm × thickness of 0.5 mm using a laminator. Subsequently, the sample was autoclaved at 50 ° C. and 0.5 MPa for 15 minutes to completely adhere the sample to the acrylic-free glass. The samples subjected to such treatment were further subjected to heat treatment at 85 ° C. for 100 hours, and then left for 1 hour under conditions of 25 ° C. and relative humidity 55% RH. It was placed on a horizontal plane so that the surface on which it was located was lower, and the distance (mm) of the longest point from the horizontal plane among the four corners was measured. The evaluation criteria are as follows.

-Evaluation criteria-
A: Warpage amount 0 mm or more and less than 0.5 mm ○: Warpage amount 0.5 mm or more and less than 1.0 mm Δ: Warpage amount 1.0 mm or more and less than 1.5 mm ×: Warpage amount 1.5 mm or more.

<Indentation>
The adhesive produced by transferring the PET film (with the silicone layer formed thereon) immediately after coating, prepared in Examples 58 to 82 and Comparative Examples 4 to 6, was 25 ° C. and relative humidity. The optical member (double-sided protective polarizing plate with a pressure-sensitive adhesive layer) is left to stand for 2 days under 55% RH for 2 days and after aging is completed; A total of 300 specimens (samples) were produced. These sample pieces are stacked with the PET film (protective film) side of the polarizing plate (the protective film side on which the pressure-sensitive adhesive layer is not formed) facing up, a weight of 1 kg is applied from above, and the relative humidity is 23 ° C. It was left to stand for 1 day under the condition of 50% RH, and the depth of the dent was evaluated with a laser microscope (VK-X120) manufactured by Keyence Corporation. The evaluation criteria are as follows.

-Evaluation criteria-
A: The depth of the dent is 0 μm or more and less than 1 μm ◯: The depth of the dent is 1 μm or more and less than 3 μm Δ: The depth of the dent is 3 μm or more and less than 5 μm ×: The depth of the dent is 5 μm or more.

<Light leakage>
Each of the optical members produced in Examples 58 to 82 and Comparative Examples 4 to 6 was cut out as a sample so that the upper and lower polarizing plates were orthogonal to a size of 420 mm long × 320 mm wide. This sample was bonded with a laminator so as to be crossed Nicol on both surfaces of a non-alkali glass plate (Corning, Eagle XG) having a thickness of 0.7 mm. Subsequently, the autoclave process was performed for 15 minutes at 50 degreeC and 5 atm, and the process for 48 hours was performed on 85 degreeC conditions after that. The heated sample was placed on a 10,000 candela backlight, and light leakage was visually evaluated according to the following criteria.

-Visual evaluation-
A: There is no occurrence of corner unevenness and there is no problem in practical use. ○: A slight amount of corner unevenness occurs but it does not appear in the display area, so there is no problem in practical use. Although it appears slightly, there is no problem in practical use. X: Corner unevenness occurs and appears in the display area, which is problematic in practical use.

<Durability>
The optical members produced in Examples 58 to 82 and Comparative Examples 4 to 6 were cut into a 37-inch size as a sample, and a laminator was used on a non-alkali glass (Corning Corp. Eagle XG) having a thickness of 0.7 mm. Sticked. Subsequently, the sample was autoclaved at 50 ° C. and 0.5 MPa for 15 minutes to completely adhere the sample to the acrylic-free glass. Samples subjected to such treatment were subjected to the following durability tests (1) to (3), and after each test, a polarizing plate (TAC film (protective film) surface side on which an adhesive layer was formed) and glass, The external appearance was visually evaluated according to the following criteria.

(1) Treated at 85 ° C. for 500 hours (heating test)
(2) Treated in an atmosphere of 60 ° C. and relative humidity of 95% RH for 500 hours (humidification test)
(3) After being left for 30 minutes in an environment at 85 ° C. and then left for 30 minutes in an environment at −40 ° C., one cycle was treated for 300 cycles (300 hours) for one hour (heat shock (HS) test) ).

-Visual evaluation-
◎: No change in appearance such as foaming, peeling, no floating ○: Slightly peeling or foaming at the end, but no problem in practical use △: Peeling or foaming at the end, but special There is no practical problem if it is not a proper use.

<Reworkability>
Samples obtained by cutting the optical members produced in Examples 58 to 82 and Comparative Examples 4 to 6 to a width of 25 mm × a length of 100 mm are Sample 1, and samples obtained by cutting to a length of 420 mm × width of 320 mm are Sample 2 (three pieces are produced). It was. Samples 1 and 2 were each attached to a non-alkali glass plate (Corning Corp., Eagle XG) with a thickness of 0.7 mm using a laminator, and then autoclaved at 50 ° C. and 5 atm for 15 minutes to completely Close contact (initial). Thereafter, heat treatment was performed for 48 hours under a dry condition of 50 ° C. (after heating).

  The adhesive strength of Sample 1 was measured. The adhesive strength was measured according to JIS Z0237 (Peeling angle 180 °, peeling speed 300 mm / min, using a tensile tester (Tensilon Universal Material Tester STA-1150, manufactured by Orientec Co., Ltd.) under the conditions of 23 ° C. and 50% RH. In accordance with the adhesive tape and adhesive sheet test method of 2009), the adhesive strength (N / 25 mm) when peeling sample 1 was determined.

  Moreover, about the said sample 2 (3 sheets), the sample was peeled off from the alkali free glass plate by human hand, and rework property was evaluated on the following reference | standard (actual rework property).

-Evaluation-
◎: All three sheets can be peeled off satisfactorily without any adhesive residue or film. ○: Some of the three sheets were broken, but were peeled off by peeling again. △: All three sheets were broken, but again X: Peeled off in all three sheets, or the film was broken and could not be peeled, no matter how many times it was peeled off.

  As described above, the results of the adhesive strength and the actual reworkability were synthesized, and the reworkability of the samples of Examples 58 to 82 and Comparative Examples 4 to 6 was determined.

  As is clear from Table 5, the double-sided protective polarizing plates with pressure-sensitive adhesive layers (Examples 58 to 82) using the pressure-sensitive adhesive composition for optical films of the present invention were all in harsh environments (high temperature, high It has been found that both durability and reworkability in humidity and heat shock can be achieved, light leakage can be sufficiently suppressed, and generation of both warpage and dents can be suppressed. Specifically, the double-sided protective polarizing plate with pressure-sensitive adhesive layer (Examples 58 to 82), which is an optical member having a pressure-sensitive adhesive layer obtained from the pressure-sensitive adhesive composition for optical films of the present invention, is used in a high-temperature and high-humidity environment. In the durability test, there was no peeling, floating or foaming due to the adhesive. In addition, the adhesive force can be lowered immediately after the double-sided protective polarizing plate (adhesive optical film) with an adhesive layer, which is an optical member, is attached to an image display device that is thinner than before, such as a liquid crystal cell of a large liquid crystal display device. In addition, even if it passes for a long time by passing through various processes, etc., it is not increased in adhesion to the liquid crystal cell etc. even if it is stored at a high temperature, and the adhesive layer which is an optical member from the liquid crystal cell etc. The double-sided protective polarizing plate (adhesive optical film) could be easily peeled off. Thereby, it was confirmed that it was excellent in reworkability and could be reused without damaging or contaminating the liquid crystal cell or the like. In addition, in a liquid crystal cell or the like used for a large-sized image display device, it has been difficult to suppress both warpage of the liquid crystal cell and the dent of the adhesive layer at the same time in the present invention (Examples 58 to 82). According to the results, it was confirmed that these characteristics could be satisfied at the same time. On the other hand, the double-sided protective polarizing plate with a pressure-sensitive adhesive layer of Comparative Example 4 is insufficient in both durability and reworkability in a harsh environment (high temperature, high humidity, heat shock) (evaluation: poor x). I understood. It was also found that the occurrence of dents could not be suppressed. Moreover, it turned out that all the double-sided protective polarizing plates with the adhesive layer of Comparative Examples 5-6 cannot suppress generation | occurrence | production of curvature. Furthermore, it was found that light leakage could not be suppressed.

Claims (26)

A pressure-sensitive adhesive composition for an optical film comprising a (meth) acrylate copolymer (A) and an isocyanate compound (B),
The (meth) acrylate copolymer (A) comprises (a1) a structural unit derived from an alkyl (meth) acrylate monomer, (a2) a structural unit derived from a (meth) acrylate monomer having a hydroxyl group, and (a3) an aromatic A structural unit derived from a (meth) acrylate monomer having a ring, and
The isocyanate compound (B) is a pressure-sensitive adhesive composition for an optical film having a number average molecular weight of 900 or more and 10,000 or less.   The content of the structural unit derived from the (a2) hydroxyl group-containing (meth) acrylate monomer is 0.01% with respect to 100% by mass of the total amount of the structural units constituting the (meth) acrylate copolymer (A). The pressure-sensitive adhesive composition for an optical film according to claim 1, wherein the pressure-sensitive adhesive composition is not less than 10% by mass and not more than 10% by mass.   The content of the isocyanate compound (B) is 0.01 part by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the (meth) acrylate copolymer (A). An adhesive composition for optical films.   The pressure-sensitive adhesive composition for an optical film according to any one of claims 1 to 3, wherein NCO% of the isocyanate compound (B) is 0.5% or more and 15% or less.   The cross-linking agent (C) other than the isocyanate compound (B): 0.01 parts by mass or more and 10 parts by mass or less is further included with respect to 100 parts by mass of the (meth) acrylate copolymer (A). 5. The optical film pressure-sensitive adhesive composition according to any one of 4 above.   The pressure-sensitive adhesive composition for an optical film according to any one of claims 1 to 5, wherein the (meth) acrylate copolymer (A) has a weight average molecular weight of 1,000,000 to 2,500,000. The pressure-sensitive adhesive composition for an optical film further contains a solvent,
The (meth) acrylate copolymer (A) has a weight average molecular weight of 300,000 or more and less than 1,000,000 by gel permeation chromatography,
The solid content including the (meth) acrylate copolymer (A) is 20% by mass or more, the content of the solvent is 80% by mass or less, and a B-type viscometer at 23 ° C. at 20 rpm. Viscosity is 200 mPa * s or more and 5000 mPa * s or less, The adhesive composition for optical films of any one of Claims 1-5 characterized by the above-mentioned.   The silane coupling agent (D): 0.01 mass part or more and 1 mass part or less are further included with respect to 100 mass parts of the said (meth) acrylate copolymer (A), The any one of Claims 1-7. The adhesive composition for optical films as described in any one of Claims 1-3. The pressure-sensitive adhesive composition for an optical film according to any one of claims 1 to 8, further comprising a silicate oligomer (E) having a structure represented by the following chemical formula (1):
In the chemical formula (1),
R ¹ and R ² are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a phenyl group;
X ¹ and X ² are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or a phenyl group;
n is an integer of 1 or more and 100 or less.   The pressure-sensitive adhesive composition for an optical film according to claim 9, wherein the silicate oligomer (E) contains a methyl silicate oligomer.   The pressure-sensitive adhesive composition for an optical film according to claim 9 or 10, wherein the silicate oligomer (E) has a weight average molecular weight of 300 or more and 30,000 or less.   The said crosslinking agent (C) contains at least 1 type selected from the group which consists of a carbodiimide type crosslinking agent, an oxazoline type crosslinking agent, an epoxy type crosslinking agent, an aziridine type crosslinking agent, and an isocyanate type crosslinking agent. The adhesive composition for optical films of any one of these.   The pressure-sensitive adhesive composition for an optical film according to any one of claims 1 to 12, further comprising a peroxide (F) as a crosslinking agent other than the crosslinking agent (C).   The pressure-sensitive adhesive composition for an optical film according to claim 13, wherein the peroxide (F) has a half-life temperature of 1 minute to 80 ° C to 125 ° C.   The pressure-sensitive adhesive composition for optical films according to any one of claims 1 to 14, further comprising a high softening point resin (G) having a softening point of 60 ° C or higher and 200 ° C or lower.   The pressure-sensitive adhesive composition for an optical film according to claim 15, wherein the high softening point resin (G) is a rosin ester resin.   The said (meth) acrylate copolymer (A) contains the structural unit (a ') derived from the (meth) acryl monomer whose glass transition temperature of a homopolymer is 50 degreeC or more. 16. The optical film pressure-sensitive adhesive composition according to any one of 16 above.   Furthermore, it contains a structural unit derived from a (meth) acrylic monomer having a weight average molecular weight (Mw) smaller than that of the (meth) acrylate copolymer (A) and a glass transition temperature of the homopolymer of 50 ° C. or more (meta) The pressure-sensitive adhesive composition for optical films according to any one of claims 1 to 17, further comprising an acrylic (co) polymer (H).   The pressure-sensitive adhesive composition for an optical film according to claim 18, wherein the (meth) acrylic (co) polymer (H) has a weight average molecular weight (Mw) in the range of 500 to 100,000. .   The adhesive layer for optical films formed from the adhesive composition for optical films of any one of Claims 1-19. The pressure-sensitive adhesive layer for an optical film according to claim 20, wherein the intrinsic birefringence is −0.5 × 10 ⁻⁴ or more and 0 or less. The pressure-sensitive adhesive layer for an optical film according to claim 20 or 21,
An optical film provided on one surface of the pressure-sensitive adhesive layer;
An optical member.   The optical member according to claim 22, further comprising at least one easy adhesion treatment layer between the optical film and the pressure-sensitive adhesive layer for the optical film. On the surface of the optical film facing the pressure-sensitive adhesive layer for the optical film, a first easy adhesion treatment layer is provided,
The optical member according to claim 23, comprising a second easy-adhesion treatment layer on a surface of the pressure-sensitive adhesive layer for the optical film facing the optical film.   The optical member according to any one of claims 22 to 24, wherein the optical film is a polarizing plate.   An image display device using at least one optical member according to any one of claims 22 to 25.