JP2018024831A - Adhesive composition for optical films, adhesive layer and method for producing the same, optical member, and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide means for an adhesive composition for optical films, which is used in an image display device and an optical member, whereby the adhesive composition has both durability and reworkability under severe environments (high temperature, high humidity, or heat shock).SOLUTION: An adhesive composition for optical films has a (meth) acrylate copolymer (A), a peroxide (B), and a crosslinker (C) other than the peroxide. A content of the peroxide (B) is more than 2.0 pts.mass and 10 pts.mass or less relative to the (meth) acrylate copolymer (A) 100 pts.mass, and the crosslinker (C) other than the peroxide is free of block isocyanate compounds.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. Furthermore, the present invention also relates to an optical member using the pressure-sensitive adhesive layer and an image display device using the optical member. Furthermore, this invention relates also to the manufacturing method of the said adhesive layer.

  A polarizing film (polarizing plate) is indispensable for a liquid crystal panel such as a liquid crystal display device which is a kind of image display device. In addition, optical members such as various optical films are attached to improve the display quality of the display. When these optical members are attached to a liquid crystal panel, an adhesive is usually used. In addition, a pressure-sensitive adhesive is usually used when two or more optical films of the same type or different types are attached to each other.

  As a necessary characteristic of the pressure-sensitive adhesive, durability in the adhesive state of the pressure-sensitive adhesive is required. The durability refers to a property that does not cause problems such as peeling and floating due to the pressure-sensitive adhesive as compared with a conventional durability test by heating and humidification as a conventional environmental promotion test. On the other hand, in recent years, optical films used for in-vehicle panels have been required to have superior durability compared to conventional ones. That is, it is required that problems such as peeling and floating due to the pressure-sensitive adhesive do not occur in a durability test under a higher temperature and higher humidity environment than in the past.

  In addition, when an optical film is bonded to a liquid crystal panel using an adhesive, the bonded position may be wrong or a foreign object may be caught in the bonded surface. In such a case, it is necessary to peel off the optical film from the liquid crystal panel and perform pasting again. In particular, in recent years, in addition to the manufacturing process of the conventional liquid crystal display device, the use of liquid crystal display devices such as thin liquid crystal panels using chemically etched glass has increased, and the optical film has become thin and brittle. . Therefore, when the conventional adhesive only aiming at durability is used for such a thin liquid crystal display device and a thin optical film, the following problems have arisen. That is, there is a problem that the thin liquid crystal display device and the thin optical film are broken or broken. For this reason, in the peeling process, an adhesive property called reworkability has been required. Such reworkability refers to re-peelability that allows an optical film to be easily peeled off from a liquid crystal display device or the like without adhesive residue.

  Moreover, in order to improve productivity, it is more desirable to have excellent handling properties in terms of the manufacturing process.

  As such an adhesive, an acrylic adhesive is widely used. In general, bonding using an acrylic pressure-sensitive adhesive containing a solvent is performed as follows. That is, first, a pressure-sensitive adhesive composition containing a (meth) acrylate-based resin and a crosslinking agent is prepared, and this is applied to the release surface side of the process film. And the layer which consists of an adhesive composition after application | coating is dried, and after that, a crosslinked structure is formed between (meth) acrylate type resin. If the pressure-sensitive adhesive layer formed on the process film side is transferred to one surface of the optical film as an adherend, an optical member (adhesive optical film) including the process film is obtained. Thereafter, the optical film having the pressure-sensitive adhesive layer from which the process film is peeled off is bonded to another optical film or a liquid crystal panel as the other adherend. As a result, the two adherends are in close contact with the adhesive layer. Thus, when the adhesive layer which gave the crosslinking process to the one surface of an optical film previously is formed, there exists a merit that the drying process for adhering becomes unnecessary after bonding.

  Many proposals have been made for the method for producing the pressure-sensitive adhesive composition for optical films or the pressure-sensitive adhesive layer as described above.

  For example, Patent Documents 1 to 3 disclose optical film pressure-sensitive adhesives containing an acrylic polymer (A), a peroxide (B), and an isocyanate compound (C). The acrylic polymer (A) contains an alkyl (meth) acrylate and a hydroxyl group-containing (meth) acrylic monomer as a copolymerization component. The content of the peroxide (B) is 0.02 to 2 parts by weight with respect to 100 parts by weight of the acrylic polymer (A). Content of the said isocyanate type compound (C) is 0.001-2 weight part with respect to 100 weight part of said acrylic polymers (A). With such a configuration, it is possible to suppress warpage and light leakage caused by stress accompanying dimensional change of a member such as an optical film. In addition, by using these pressure-sensitive adhesive compositions, it is possible to obtain a high-quality pressure-sensitive adhesive optical film having high durability and excellent handling properties in the production process.

  Patent Document 4 discloses a pressure-sensitive adhesive layer formed by subjecting the following pressure-sensitive adhesive composition to a peroxide crosslinking agent treatment. The pressure-sensitive adhesive composition comprises 100 parts by weight of an acrylic polymer, 0.02 to 2 parts by weight of a peroxide, and 0.01 to 1 part by weight of a silane coupling agent. The acrylic polymer contains an acrylic ester having an alkyl group having 4 or more carbon atoms as a monomer unit. The gel fraction after the crosslinking treatment of the pressure-sensitive adhesive layer is 30 to 90% by weight.

  Patent Document 5 discloses a pressure-sensitive adhesive composition containing a (meth) acrylic polymer, an aliphatic and / or alicyclic isocyanate crosslinking agent, a peroxide, and a silane coupling agent. The (meth) acrylic polymer contains an alkyl (meth) acrylate having an alkyl group having 4 or more carbon atoms as a monomer unit and an unsaturated carboxylic acid. Content of the said aliphatic and / or alicyclic isocyanate type crosslinking agent is 0.01-5 weight part with respect to 100 weight part of said (meth) acrylic-type polymers. The content of the peroxide is 0.02 to 2 parts by weight with respect to 100 parts by weight of the (meth) acrylic polymer. Content of the said silane coupling agent is 0.01-1 weight part with respect to 100 weight part of said (meth) acrylic-type polymers.

  Patent Document 6 discloses a pressure-sensitive adhesive layer formed of a pressure-sensitive adhesive composition containing 100 parts by weight of an acrylic polymer and 0.02 to 2 parts by weight of a peroxide. The acrylic polymer contains an acrylic ester having an alkyl group having 4 or more carbon atoms as a monomer unit. The pressure-sensitive adhesive layer has a thickness of 20 μm or more.

  According to the said patent documents 4-6, the optical member has the following merit in the structure of the adhesive composition which concerns. That is, even when the screen display device is reused after the optical member is attached and peeled off, there is a merit that a significant increase in adhesion force and contamination of the adherend are observed. Moreover, it has the merit which is excellent in durability which does not peel or float even if it preserve | saves at high temperature and high humidity. Further, after the optical member with the pressure-sensitive adhesive is manufactured, there is a merit of excellent productivity that can be quickly punched.

Patent Document 7 discloses a pressure-sensitive adhesive composition containing a (meth) acrylic polymer, a peroxide as a crosslinking agent, and an epoxy crosslinking agent. The (meth) acrylic polymer contains an alkyl (meth) acrylate having an alkyl group as a monomer unit and a carboxyl group-containing monomer as a copolymerization component. The content of the peroxide as the crosslinking agent is 0.02 to 2 parts by weight with respect to 100 parts by weight of the (meth) acrylic polymer. Content of the said epoxy type crosslinking agent is the said (meth) acrylic-type polymer 1
It is 0.005-5 weight part with respect to 00 weight part. According to the literature, yellowing in a high temperature and high temperature and humidity environment can be suppressed. Moreover, the adhesive layer which can suppress foaming, peeling, etc. in a high temperature and high temperature and high humidity environment can be formed.

  Patent Documents 8 to 11 disclose a method for producing a pressure-sensitive adhesive layer.

  Specifically, Patent Document 8 discloses a method for producing an adhesive layer in which an adhesive is subjected to a crosslinking reaction to form an adhesive layer. The pressure-sensitive adhesive contains a (meth) acrylic polymer (A), a peroxide (B), and an isocyanate compound (C). The (meth) acrylic polymer (A) contains an alkyl (meth) acrylate and a hydroxyl group-containing (meth) acrylic monomer as a copolymerization component. The content of the peroxide (B) is 0.02 to 2 parts by weight with respect to 100 parts by weight of the (meth) acrylic polymer (A). Content of the said isocyanate type compound (C) is 0.001-2 weight part with respect to 100 weight part of said (meth) acrylic-type polymers (A). Patent Document 9 discloses a method for producing a pressure-sensitive adhesive layer using a pressure-sensitive adhesive composition having the same composition as Patent Document 8. According to these patent documents, the obtained pressure-sensitive adhesive optical film can suppress warpage and light leakage caused by stress accompanying dimensional change of a member such as an optical film. Further, the pressure-sensitive adhesive optical film has high durability and has excellent handling properties in the manufacturing process.

  Patent Documents 10 and 11 disclose a method for producing a pressure-sensitive adhesive layer with a separator including a first step and a second step. In the first step, a layer of a pressure-sensitive adhesive composition containing a (meth) acrylic polymer, a peroxide, and a phenolic antioxidant is formed on the release-treated surface of the release-treated separator. In the second step, the pressure-sensitive adhesive composition is heated and cross-linked after the first step to form a pressure-sensitive adhesive layer. According to these patent documents, the separator has an appropriate light peelability for the pressure-sensitive adhesive layer, and a pressure-sensitive adhesive layer with a separator excellent in workability and durability can be produced.

JP 2006-183022 A JP 2012-037895 A JP 2012-108542 A JP 2006-348307 A JP 2006-143858 A JP 2007-112901 A JP 2009-242786 A JP 2007-107016 A JP 2012-031419 A Japanese Patent Laying-Open No. 2015-025125 Japanese Patent Laying-Open No. 2015-165030

  However, according to the study by the present inventors, it was found that the following problems could not be solved even with the pressure-sensitive adhesive layers described in Patent Documents 1 to 11. Specifically, it has been found that the durability and reworkability in a harsh environment (high temperature, high humidity, heat shock) may not be sufficiently achieved.

  Then, this invention is made | formed in view of the said situation, and it aims at providing the means which can solve the said subject in the adhesive composition for optical films which concerns on this invention.

  Another object of the present invention is to provide an adhesive layer formed from such an adhesive composition, an optical member using the adhesive layer, and an image display device using the optical member. is there.

  Yet another object of the present invention is to provide a method for producing the pressure-sensitive adhesive layer of the present invention.

  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 is a pressure-sensitive adhesive composition for an optical film comprising a (meth) acrylate copolymer (A), a peroxide (B), and a crosslinking agent (C) other than peroxide, Content of an oxide (B) is more than 2.0 mass parts with respect to 100 mass parts of the said (meth) acrylate copolymers (A), and is 10 mass parts or less, and crosslinking agents other than the said peroxide. (C) is an optical film pressure-sensitive adhesive composition that does not contain a blocked isocyanate compound.

  ADVANTAGE OF THE INVENTION According to this invention, in the adhesive composition for optical films, the durability in severe environments (high temperature, high humidity, heat shock) and the rework property which can peel an optical film easily from a liquid crystal panel are made compatible. Means that can be provided 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 according to the present invention comprises a (meth) acrylate copolymer (A), a peroxide (B), and a crosslinking agent (C) other than the peroxide. The content of B) is more than 2.0 parts by mass and 10 parts by mass or less with respect to 100 parts by mass of the (meth) acrylate copolymer (A), and the crosslinking agent (C) other than the peroxide. However, it does not contain a blocked isocyanate compound.

  According to the pressure-sensitive adhesive composition for an optical film of the present invention having such a configuration, the rework that can easily peel off the optical film from the liquid crystal panel and durability in a harsh environment (high temperature, high humidity, heat shock). It can be compatible with sex.

  Moreover, the pressure-sensitive adhesive composition for optical films according to the present invention hardly contaminates the liquid crystal panel, and has good adhesive chipping from the end when the optical member is cut and used. In the present specification, “adhesive chipping” refers to the end of an optical member having a pressure-sensitive adhesive layer using the pressure-sensitive adhesive composition of the present invention (for example, a polarizing plate). It means the property that the adhesive layer is missing from the part (cut surface). The degree of “glue chipping” is evaluated according to the criteria described in the examples.

  Furthermore, the pressure-sensitive adhesive composition for an optical film according to the present invention has excellent handling properties such as not requiring aging when a pressure-sensitive adhesive layer is produced or an optical member is produced.

Hereinafter, each component which comprises the adhesive composition for optical films which concerns on 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”. The “(meth) acrylate copolymer (A)” is also referred to as “copolymer (A)”.

<(Meth) acrylate copolymer (A)>
The pressure-sensitive adhesive composition for an optical film according to the present invention essentially contains a (meth) acrylate copolymer (A). Adhesiveness (adhesiveness) is exhibited when the copolymer (A) reacts with a peroxide (B) described later and / or a crosslinking agent (C) other than the peroxide to form a crosslinked structure. .

  Although it does not restrict | limit especially as a weight average molecular weight (Mw) of the copolymer (A) based on this invention, From a viewpoint of durability and the productivity at the time of coating, it is 800,000 or more and 2.5 million or less, and 1.3 million or more and 220 It is preferably 10,000 or less, and more preferably 1.5 to 2 million. The weight average molecular weight (Mw) of the copolymer (A) according to the present invention is determined by appropriately adjusting the polymerization initiator used in the polymerization reaction described later, reaction conditions such as reaction temperature and reaction time, and the like. If it is a trader, it can be easily controlled. In addition, in this specification, a weight average molecular weight can be measured by the method shown in an Example.

  In the present invention, the structural unit constituting the copolymer (A) is not particularly limited, but (a1) a structural unit derived from an alkyl (meth) acrylate monomer (hereinafter also simply referred to as “component (a1)”). It is preferable to include. The component (a1), (a2) a structural unit derived from a (meth) acrylate monomer having a hydroxyl group (hereinafter also simply referred to as “component (a2)”), and (a3) the alkyl (meth) acrylate monomer and It is preferable to contain at least one of monomer-derived structural units (hereinafter also simply referred to as “component (a3)”) other than the (meth) acrylate monomer having a hydroxyl group. That is, the copolymer (A) according to the present invention preferably includes the component (a1) and the component (a2); it preferably includes the component (a1) and the component (a3); Furthermore, it is also preferable that a component (a1), a component (a2), and a component (a3) are included.

  In the copolymer (A) according to the present invention, the content of each of the components (a1), the component (a2), and the component (a3) is not particularly limited. For example, when the (meth) acrylate copolymer (A) according to the present invention includes the component (a1), the component (A) is used with respect to 100% by mass of the total amount of the constituent units constituting the copolymer (A). a1) is preferably contained in an amount of 80% by mass or more and 99.99% by mass or less; when the component (a2) is included, the component is included with respect to 100% by mass of the total amount of the structural units constituting the copolymer (A). Preferably, (a2) is contained in an amount of 0.01% by mass or more and 5% by mass or less; when the component (a3) is contained, the total amount of the structural units constituting the copolymer (A) is 100% by mass. It is preferable that the component (a3) is contained more than 0% by mass and 15% by mass or less. The copolymer (A) according to the present invention can optionally contain the component (a1), the component (a2) and the component (a3), but the component (a1), the component (a2) and the component ( The total amount of a3) is 100% by mass. For example, when the (meth) acrylate copolymer (A) includes all of the component (a1), the component (a2) and the component (a3), the sum of the component (a1), the component (a2) and the component (a3) When the amount is 100% by mass and any one or more of the constituent units derived from the components is not included, the total amount of the remaining components is 100% by mass.

In the present specification, “the copolymer X contains y mass% of the structural unit derived from the monomer Y” means the total amount of all raw material monomers used when the copolymer X is obtained by copolymerization. It means that the monomer Y as the raw material monomer is blended by y% by mass with respect to 100% by mass. Therefore, the copolymer (A) according to the present invention has, for example, 80% by mass to 99.99% by mass of the structural unit derived from the above-described (a1) alkyl (meth) acrylate monomer and (a2) a hydroxyl group ( Structural unit derived from (meth) acrylate monomer 0.01% by mass or more and 5% by mass or less, (a3) Structural unit derived from monomer other than components (a1) and (a2) exceeding 0% by mass and 15% by mass or less, In other words, (a1) alkyl (meth) acrylate monomer 80 mass% or more and 99.99 mass% or less; (a2) (meth) acrylate monomer having a hydroxyl group 0.01 mass% or more and 5 mass% And (a3) a copolymer obtained by copolymerizing monomers other than (a1) and (a2) above 0% by mass and 15% by mass or less. Rutoieru.

  Hereinafter, the structural unit derived from each monomer that can constitute the copolymer (A) according to the present invention will be described in order.

[(A1) Structural unit derived from alkyl (meth) acrylate monomer]
The copolymer (A) according to the present invention preferably contains a structural unit derived from (a1) an alkyl (meth) acrylate monomer. By including such a component (a1) as a structural unit of the 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 from the viewpoints of versatility, price, and handling, and the carbon number is more preferably 1 or more and 12 or less, and more preferably 1 or more and 10 or less. It is preferably 1 or more and 8 or less, more 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-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, lauryl (meth) acrylate, etc. are mentioned. Of these, methyl (meth) acrylate and n-butyl (meth) acrylate are preferable from the viewpoint of heat durability and adhesive strength. In addition, these can be used individually or in mixture of 2 or more types.

  In the copolymer (A) according to the present invention, the content of the component (a1) (the alkyl (meth) acrylate monomer as a raw material monomer) with respect to 100% by mass of the total amount of the constituent units constituting the copolymer (A) Is not particularly limited, but is preferably 80% by mass or more and 99.99% by mass or less. When the content is 80% by mass or more, the balance with the other raw material monomers can be well maintained, and the durability can be improved. On the other hand, if it is 99.99% by mass or less, the proportion of the other monomer to be blended is not excessively small, adhesion to the liquid crystal panel can be secured, and durability is not deteriorated.

  The content of the component (a1) is more preferably 80% by mass or more and 99.9% by mass or less, and still more preferably 80% by mass or more and 99.5% by mass from the viewpoint of further exerting the effects of the present invention. Or less, more preferably 82% by mass or more and 99.3% by mass or less, and particularly preferably 85% by mass or more and 99% by mass or less.

[(A2) a structural unit derived from a (meth) acrylate monomer having a hydroxyl group]
The copolymer (A) according to the present invention preferably includes (a2) a structural unit derived from a (meth) acrylate monomer having a hydroxyl group. Such a component (a2) is preferable from the viewpoint of reworkability by being contained as a constituent unit of the copolymer (A) according to the present invention, and is rich in reactivity with an intermolecular crosslinking agent, and will be described later. It is considered that it has the significance of improving the cohesiveness and heat resistance of the pressure-sensitive adhesive layer.

  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, from the viewpoint of efficiently functioning as a crosslinking point when an isocyanate crosslinking agent described later is used, 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxyethyl (meth) acrylamide, Cyclohexanedimethanol monoacrylate and the like are preferable, and 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate are more preferable. In addition, these can be used individually or in mixture of 2 or more types.

In the copolymer (A) according to the present invention, the content of the component (a2) (the amount of the (meth) acrylate monomer having a hydroxyl group as a raw material monomer) is not particularly limited, but the copolymer (A) It is preferable that they are 0.01 mass% or more and 5 mass% or less with respect to 100 mass% of the whole quantity of the structural unit which comprises. A crosslinking reaction point can be ensured as it is 0.01 mass% or more, and durability can be improved. On the other hand, when the content is 5% by mass or less, the proportion of the polar monomer to be blended is not excessively increased, the polarity of the formed pressure-sensitive adhesive layer is maintained in a well-balanced manner, and durability can be improved.

  The content of the component (a2) is more preferably 0.1% by mass or more and 5% by mass or less, and further preferably 0.3% by mass or more and 4% by mass from the viewpoint of further exerting the effects of the present invention. Or less, and particularly preferably 0.5% by mass or more and 3% by mass or less.

[(A3): a structural unit derived from a monomer other than the above (a1) and (a2)]
The copolymer (A) according to the present invention includes, as an optional component, the alkyl (meth) acrylate monomer and the (meth) acrylate monomer having a hydroxyl group, which are copolymerizable with the components (a1) and (a2) described above. Other than the above, a structural unit derived from a monomer can be included.

  As a component (a3), 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 (a3). 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. The content when the unsaturated carboxylic acid is included as the component (a3) is 100% by mass based on the total amount of the structural units constituting the copolymer (A) from the viewpoint of achieving both durability and reworkability. It is preferably more than 0% by mass and 5% by mass or less, more preferably more than 0% by mass and 2% by mass or less.

  Moreover, it is preferable that an aromatic ring containing (meth) acrylate monomer is included as a component (a3) from a viewpoint of suppressing light leakage. Specific examples of such aromatic ring-containing (meth) acrylate monomers include benzyl (meth) acrylate, phenyl (meth) acrylate, o-phenylphenol (meth) acrylate, phenoxymethyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenoxy Propyl (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, cresyl (meth) acrylate, poly Those having a benzene ring such as tyryl (meth) acrylate; hydroxyethylated β-naphthol acrylate, 2-naphthoethyl (meth) acrylate, 2-naphthoxyethyl acrylate, 2- (4-methoxy-1-naphthoxy) ethyl (meta ) Those having a naphthalene ring such as acrylate; those having a biphenyl ring such as biphenyl (meth) acrylate. Of these, benzyl (meth) acrylate and phenoxyethyl (meth) acrylate are preferable from the viewpoint of imparting optical characteristics such as light leakage. In the present invention, the content (blending amount) of the aromatic ring-containing (meth) acrylate monomer contained in the component (a3) is a copolymer (A) from the viewpoint of imparting optical characteristics such as light leakage. ) Is preferably 5% by mass or more and 30% by mass or less, and more preferably 10% by mass or more and 20% by mass or less, with respect to 100% by mass of the total amount of the structural units constituting.

  As the component (a3), a (meth) acrylate monomer having an alkoxyalkyl group or an alkylene oxide group is also preferably used.

  Examples of (meth) acrylate monomers having an alkoxyalkyl group or an alkylene oxide group include methoxyethyl (meth) acrylate, ethoxymethyl (meth) acrylate, ethoxyethyl (meth) acrylate, propoxyethyl (meth) acrylate, butoxyethyl (meth) ) Acrylate, methoxypropyl (meth) acrylate, methoxybutyl (meth) acrylate; ethoxy-diethylene glycol (meth) acrylate, ethoxy-triethylene glycol (meth) acrylate, methoxy-triethylene glycol (meth) acrylate, methoxy-diethylene glycol (meta ) Acrylate, propoxy-diethylene glycol (meth) acrylate, methoxy-triethylene glycol (meth) acrylate , 2-ethylhexyloxy-didiethylene glycol (meth) acrylate, methoxy-polyethylene glycol (meth) acrylate (n = 4-10), methoxydipropylene glycol (meth) acrylate, 2-ethylhexyl-diglycol acrylate, etc. However, it is not limited to these.

  In the present invention, the content (blending amount) of the (meth) acrylate monomer having an alkoxyalkyl group or an alkylene oxide group is included in the component (a3) from the viewpoint of achieving both durability and reworkability. It is preferably 1% by mass or more and 95% by mass or less, and more preferably 5% by mass or more and 90% by mass or less with respect to 100% by mass of the total amount of the structural units constituting the polymer (A).

  Furthermore, as a component (a3), acrylic monomers having an epoxy group such as glycidyl (meth) acrylate and methylglycidyl (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, etc. Acrylic monomer having an amide group: 2-methacryloyloxyethyl diphenyl phosphate (meth) acrylate, trimethacryloyloxyethyl phosphate (meth) acrylate, triacrylic Acrylic monomer having phosphoric acid group such as yloxyethyl phosphate (meth) acrylate; sulfone such as sodium sulfopropyl (meth) acrylate, sodium 2-sulfoethyl (meth) acrylate, sodium 2-acrylamido-2-methylpropanesulfonate Acrylic monomers having acid groups; acrylic monomers having urethane groups such as urethane (meth) acrylate; acrylic vinyl monomers having phenyl groups such as p-tert-butylphenyl (meth) acrylate and o-biphenyl (meth) acrylate; 2 -Acetoacetoxyethyl (meth) acrylate, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (β-methoxyethyl) silane, vinyltriacetylsilane, methacryloyloxy Examples of the vinyl monomer having a silane group such as propyltrimethoxysilane; styrene, chlorostyrene, α-methylstyrene, vinyl 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 (a3). Further, when producing the copolymer (A) according to the present invention, from the viewpoint that the reaction with the crosslinking agent described later can be easily controlled, and from the problem that the molecular weight is difficult to increase due to copolymerization problems, It is preferable that the component (a3) does not contain an olefin monomer.

In the case where the copolymer (A) according to the present invention includes structural units derived from the components (a1), (a2) and (a3), the total amount of the components (a1), (a2) and (a3) is 100. However, when an arbitrary component (a3) is used, the content is not particularly limited, and a suitable range can be determined depending on the type of monomer that can be the component (a3) described above. In addition, it is preferable that it is 15 mass% or less from a viewpoint that it does not become low molecular weight by the durability fall by the polarity raise of an adhesive layer, or the degree of polymerization, and the risk that a durability fall occurs is also suppressed.

  The component (a3) is preferably more than 0% by mass and 10% by mass or less, more preferably from the viewpoint of more efficiently achieving the effects of the present invention in combination with the components (a1) and (a2) described above. Is 0.1 mass% or more and 5 mass% or less, More preferably, it is 0.5 mass% or more and 3 mass% or less.

  As the 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 copolymer (A) is demonstrated. In the present invention, the production method of the 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 polymerization method, a thin film. Conventionally known methods such as a 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 the solution polymerization method using a thermal polymerization initiator, a monomer solution that is a raw material for the copolymer (A), for example, an alkyl (meth) acrylate monomer and a (meth) acrylate monomer having a hydroxyl group, and the above optionally contained A thermal polymerization initiator is added to a raw material monomer solution composed of monomers other than the above, and a polymerization reaction is performed. More specifically, using ethyl acetate, toluene, methyl ethyl ketone, acetone, or the like as a solvent, and preferably adding 0.01 to 1 part by mass of a thermal polymerization initiator to 100 parts by mass of the total amount of raw material monomers 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'-azobis [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) dihydrochloride, 2,2 Azo compounds such as' -azobis [2-methyl-N- (2-hydroxyethyl) propionamide]; t-butylperoxypivalate, t-butylperoxybenzoate, t-butylperoxy-2-ethylhexano Ate, di-t-butyl peroxide, cumene hydroperoxide, benzoyl peroxide Organic peroxides such as id 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. Examples thereof include a method of obtaining a copolymer (A) by stopping the reaction by introducing air into the reaction system when the temperature in the reaction system has increased by 5 ° C. or more and 15 ° C. or less from the reaction start temperature. .

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 parts by mass or more and 1 part by mass or less, more preferably 0.002 parts by mass or more and 0.5 parts by mass or less with respect to 100 parts by mass of the total amount of raw material monomers. is there.

Moreover, in order to adjust the molecular weight of a copolymer (A), a chain transfer agent can also be used. For example, methyl mercaptan, t-butyl mercaptan, decyl mercaptan, benzyl mercaptan, stearyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, mercaptoacetic acid, mercaptopropionic acid and its ester, 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.

<Peroxide (B)>
The pressure-sensitive adhesive composition for an optical film of the present invention contains a peroxide (B) as an essential component. In the present specification, “peroxide” means a compound having a peroxide structure “—O—O—” in the molecular structure.

  In the present invention, the peroxide (B) may act as a crosslinking agent, may act as a polymerization initiator, or may have both roles.

  It does not specifically limit as a peroxide (B) concerning this invention, A well-known thing can be used. In addition, the peroxide (B) preferably has a one-minute half-life temperature of 80 ° C. or higher and 160 ° C. or lower, more preferably 80 ° C. or higher and 140 ° C. or lower in consideration of productivity and stability. Preferably, the temperature is from 80 ° C. to 125 ° C., more preferably from 90 ° C. to 125 ° C.

  “Peroxide half-life” is an index representing the decomposition rate of peroxide, and means the time until the remaining amount of peroxide is halved. The decomposition temperature for obtaining a half-life at a certain time and the half-life time at a certain temperature are described in the manufacturer catalog, for example, the organic peroxide catalog 9th edition published by NOF Corporation (2003) May).

  Examples of such peroxides include diisopropyl peroxydicarbonate (1 minute half-life temperature 88.3 ° C), di (2-ethylhexyl) peroxydicarbonate (90.6 ° C), di (4-t- Butylcyclohexyl) peroxydicarbonate (92.1 ° C), di-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-octanoyl peroxide (117.4 ° C.), 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate (124.3 ° C.), di (4-methylbenzo Lu) peroxide (128.2 ° C), dibenzoyl peroxide (benzoyl peroxide) (130.0 ° C), a mixture of dibenzoyl peroxide, benzoyl m-methylbenzoyl peroxide and m-toluoyl peroxide (131.1 ° C.) and t-butyl peroxybutyrate (136.1 ° C.). Of these, diisopropyl peroxydicarbonate, di (4-t-butylcyclohexyl) peroxydicarbonate, and t-butylperoxyneodecanoate are preferably used. These may be used alone, but it is also preferable to use two or more in combination from the viewpoint of adjusting reactivity. As an example of using two or more kinds in combination, a combination of di (4-t-butylcyclohexyl) peroxydicarbonate and dilauroyl peroxide is preferable.

  Moreover, a peroxide may be synthesize | combined and a commercial item may be used.

Commercially available products include, for example, trade names made by NOF Corporation: “Perloyl (registered trademark) IB” (1 minute half-life temperature 85.1 ° C.), “Park Mill (registered trademark) ND” (94.0 ° C.). ), “Parroyl (registered trademark) NPP” (94.0 ° C.), “Parroyl (registered trademark) IPP” (88.3 ° C.), “Parroyl (registered trademark) SBP” (92.4 ° C.), “Perocta (registered trademark) ND” (92.4 ° C.), “Parroyl (registered trademark) TCP” (92.1 ° C.), “Parroyl (registered trademark) OPP” (90.6 ° C.), “Perhexyl” (Registered trademark) ND "(100.9 ° C)," Perbutyl (registered trademark) ND "(103.5 ° C),
“Perbutyl (registered trademark) NHP” (104.6 ° C.), “Perhexyl (registered trademark) PV” (109.1 ° C.), “Perbutyl (registered trademark) PV” (110.3 ° C.), “Parroyl (Registered trademark) 355 ”(112.6 ° C.),“ Parroyl (registered trademark) L ”(116.4 ° C.),“ Perocta® O ”(124.3 ° C.),“ Parroyl (registered) Trademark) SA "(131.8 ° C)," Perhexa (registered trademark) 25O "(118.8 ° C)," Perhexyl (registered trademark) O "(132.6 ° C)," Nyper (registered trademark) " “PMB” (128.2 ° C.), “Perbutyl (registered trademark) O” (134.0 ° C.), “Nyper (registered trademark) BMT” (131.1 ° C.), “Nyper (registered trademark) BW” (130.0 ° C), "Nyper (registration Standard) BMT-K40 ”(131.1 ° C.),“ Nyper (registered trademark) BMT-M ”(131.1 ° C.),“ Perhexa (registered trademark) MC ”(142.1 ° C.),“ Perhexa ” (Registered trademark) TMH "(147.1 ° C)," Perhexa (registered trademark) HC "(149.2 ° C)," Perhexa (registered trademark) C "(153.8 ° C)," Pertetra (registered) Trademark) A "(153.8 ° C)," Perhexyl (registered trademark) I "(155.0 ° C)," Perbutyl (registered trademark) L "(159.4 ° C)," Perbutyl (registered trademark) " I ”(158.8 ° C.),“ Perhexa (registered trademark) 25Z ”(158.2 ° C.),“ Perbutyl (registered trademark) A ”(159.9 ° C.),“ Perhexa (registered trademark) 22 ” (159.9 ° C.).

  In this invention, content of a peroxide (B) is more than 2.0 mass parts and 10 mass parts or less with respect to 100 mass parts of said copolymers (A). When the content of the peroxide (B) is 2.0 parts by mass or less, it cannot be said to be sufficient for improving the heat durability at high temperatures. On the other hand, when the amount exceeds 10 parts by mass, the crosslink density is excessively increased and the durability is deteriorated or the stability of the pressure-sensitive adhesive liquid is deteriorated.

  Further, from the viewpoint of satisfying the heat durability at high temperature, the content of the peroxide (B) exceeds 2.0 parts by mass with respect to 100 parts by mass of the copolymer (A). It is preferably 0 parts by mass or less, more preferably more than 2.0 parts by mass and 3.0 parts by mass or less.

<Crosslinking agent other than peroxide (C)>
The pressure-sensitive adhesive composition for optical films of the present invention contains a crosslinking agent (C) other than peroxide as an essential component. Since the crosslinking agent (C) other than the peroxide reacts with the (meth) acrylate copolymer (A) to form a crosslinked structure, the adhesive composition for optical films is mainly adhesive (adhesive). And can contribute to durability. Further, the reason that “other than peroxide” is defined here is to distinguish it from the “peroxide (B)” described above.

  In the present invention, the crosslinking agent (C) other than the peroxide does not contain a blocked isocyanate compound. The “block isocyanate compound” is an isocyanate compound in which an isocyanate group is protected using a blocking agent (also referred to as “protecting group”).

  Conventionally, a blocked isocyanate compound is generally used as a curing agent for a paint or the like, but a heat treatment for a long time at a high temperature is required. On the other hand, for example, JP 2011-132297 A discloses an invention in which the pressure-sensitive adhesive can be cured at a low temperature and / or in a short time by using a peroxide and a blocked isocyanate compound in combination. ing.

However, according to studies by the present inventors, it has been found that when a peroxide and a blocked isocyanate compound are used in combination, the durability of the resulting pressure-sensitive adhesive composition may be reduced. Therefore, according to the study by the present inventors, it is described in JP2011-132297A by using a crosslinking agent (C) that does not contain a blocked isocyanate compound and the specific peroxide (B) described above. It was found that the pressure-sensitive adhesive can be cured at a lower temperature and in a shorter time than the above technique, and that the durability of the obtained pressure-sensitive adhesive composition can be improved, and the present invention has been completed.

  In the present invention, the crosslinking agent (C) other than the peroxide is at least one 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. It is preferable to include. Below, various crosslinking agents are demonstrated.

[Isocyanate-based crosslinking agent]
In the present invention, an isocyanate crosslinking agent is preferably used as the crosslinking agent (C) other than the peroxide. In this case, as described above, the isocyanate crosslinking agent is used in the form of an unblocked isocyanate compound.

  In the present invention, as an isocyanate-based crosslinking agent that is preferably used, triallyl isocyanurate, dimer acid diisocyanate, 2,4-tolylene diisocyanate (2,4-TDI), 2,6-tolylene diisocyanate (2,6 -TDI), 4,4'-diphenylmethane diisocyanate (4,4'-MDI), 2,4'-diphenylmethane diisocyanate (2,4'-MDI), 1,4-phenylene diisocyanate, xylylene diisocyanate (XDI), Aromatic diisocyanates such as tetramethylxylidene diisocyanate (TMXDI), tolidine diisocyanate (TODI), 1,5-naphthalene diisocyanate (NDI); hexamethylene diisocyanate (HDI), trimethylhexamethylene diiso Aliphatic diisocyanates such as anate (TMHDI), lysine diisocyanate, norbornane diisocyanate methyl (NBDI); transcyclohexane-1,4-diisocyanate, isophorone diisocyanate (IPDI), H6-XDI (hydrogenated XDI), H12-MDI And alicyclic diisocyanates such as (hydrogenated MDI); carbodiimide-modified diisocyanates of the above diisocyanates; or their isocyanurate-modified diisocyanates. Adducts of the above isocyanate compounds and polyol compounds such as trimethylolpropane, biurets and isocyanurates of these isocyanate compounds can also be suitably used.

  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-131N, Takenate (registered trademark) D-200, Takenate (registered trademark) D-202 (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 trademark) D-101, Duranate (registered trademark) D-201 (above, manufactured by Asahi Kasei Chemicals Corporation), Sumijour (registered trademark) N-75, N-3200, N-3300 (above And Sumika Bayer Urethane Co., Ltd.). 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, Takenate (registered trademark) D-131N, Coronate (registered trademark) L, Coronate (registered trademark) HX, and Duranate (registered trademark) 24A-100 are preferable.

[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.

  As the oxazoline group-containing polymer, specifically, oxazoline group-containing products such as EPOCROSS (registered trademark) WS-300, EPOCROSS (registered trademark) WS-500, EPOCROSS (registered trademark) WS-700 manufactured by Nippon Shokubai Co., Ltd. Examples of the acrylic polymer 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. As a commercial item, for example, “TETR” manufactured by Mitsubishi Gas Chemical Co., Ltd.
AD-C "," TETRAD-X "," Adeka Resin EPU Series "and" Adeka Resin EPR Series "manufactured by ADEKA Corporation, and" Celoxide "manufactured by Daicel Corporation. In particular, liquid epoxy resins such as these are preferred in terms of facilitating mixing operations 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 cross-linking agent, for example, Chemitite (registered trademark) PZ-33, Chemitite (registered trademark) DZ-22E manufactured by Nippon Shokubai Co., Ltd. may be mentioned.

  In the present invention, the crosslinking agent (C) other than the peroxide is at least one 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. As long as a seed is included, only 1 type may be used independently and 2 or more types may be used together. 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.

  Although content in particular of crosslinking agents (C) other than a peroxide in the adhesive composition for optical films which concerns on this invention is not restrict | limited, 0.001 mass with respect to 100 mass parts of said copolymers (A). It is preferable that it is 2 parts by mass or more. When the content of the crosslinking agent (C) other than the peroxide is 0.001 part by mass or more, the crosslinking effect cannot be sufficiently obtained and durability can be ensured, and also in terms of adhesive chipping. On the other hand, when the content is 2 mass or less, the pressure-sensitive adhesive layer does not become too hard, and durability can be ensured.

  Further, from the viewpoint of further ensuring durability due to the expression of the crosslinking effect, the content of the crosslinking agent (C) other than peroxide is 0.01 parts by mass with respect to 100 parts by mass of the copolymer (A). The amount is more preferably 1.5 parts by mass or less, and particularly preferably 0.05 parts by mass or more and 1.0 part by mass or less.

<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-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-methacryloxypropyl Methyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-acryloxypropyltrimethoxysilane, N-β- (aminoethyl)- γ-aminopropylmethyldimethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-Ami Propyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, bis- (3- [triethoxysilyl ] Propyl) tetrasulfide, γ-isocyanatopropyltriethoxysilane and the like. 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 is 100 parts by mass of the copolymer (A). On the other hand, it is preferably 0.001 to 10 parts by mass, more preferably 0.005 to 5 parts by mass, and still more preferably 0.01 to 3 parts by mass, Especially preferably, it is 0.01 mass part or more and 1 mass part or less. When the content is 0.001 part by mass or more, it is preferable from the viewpoint that an effect on durability is exhibited. 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 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, from the viewpoint that durability and reworkability are both compatible, among the compounds represented by Chemical Formula 1, all of R ¹ and R ² and X ¹ and X ² are methyl silicate oligomers. Preferably there is. 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 30000 or less, more preferably 500 or more and 25000 or less, further preferably 600 or more and 5000 or less, Preferably it is 600 or more and 5000 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 30000 or less, it is preferable from the viewpoint that durability is easily secured.

  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 preferably based on 100 parts by mass of the copolymer (A). Is 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 is exhibited. 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.

<Solvent>
The pressure-sensitive adhesive composition for optical films of the present invention may contain a solvent as necessary. Solvents are 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 and methyl Examples include alicyclic hydrocarbons such as cyclohexane; and organic solvents such as ketones such as methyl ethyl ketone, methyl isobutyl ketone, and acetone. These solvents may be used alone or in combination of two or more.

  The solid content in the optical film pressure-sensitive adhesive composition is not particularly limited, but from the viewpoint of coating properties and productivity, the solid content is preferably 10% by mass or more and 50% by mass with respect to 100% by mass of the total amount of the optical film pressure-sensitive adhesive composition. It is not more than mass%, more preferably not less than 12 mass% and not more than 30 mass%.

<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.

<Method for producing (preparing) the pressure-sensitive adhesive composition>
In the present invention, the pressure-sensitive adhesive composition for optical films is not particularly limited, and optionally includes, for example, a copolymer (A), a peroxide (B), and a crosslinking agent (C) other than peroxide. A silane coupling agent (D), a silicate oligomer (E), a solvent, and other additives that can be prepared can be mixed. 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 this invention, the form of the adhesive layer formed with the adhesive composition for optical films mentioned above, the form of the optical member by which the said adhesive layer is formed in an optical film, etc., the said optical film is a polarizing plate. A form or a form 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 curved surface 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.

  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.

  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, more preferably 65% or more from the viewpoint that there is no concern about dents and 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. In addition, the value measured by the method described in the Example is employ | adopted for the gel fraction immediately after drying of an adhesive layer.

[Method for producing pressure-sensitive adhesive layer]
According to another embodiment of the present invention, the optical film pressure-sensitive adhesive composition of the present invention described above is applied on a release-treated release sheet, and then subjected to a heat treatment to cause a crosslinking reaction. A method for producing the agent layer is also provided.

  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 When sticking to an optical film, a liquid crystal panel, etc., the film which has the said release property 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.

  For release sheet, silicone, fluorine, long chain alkyl or fatty acid amide release agent, release treatment with silica powder and antifouling treatment, coating type, kneading type, vapor deposition as required An antistatic treatment such as a mold 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.

  In this invention, it does not restrict | limit especially as an application | coating system at the time of apply | coating on the release sheet which peel-processed the adhesive composition for optical films of this invention, Various well-known methods are 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.

  In the manufacturing method of the adhesive layer of this invention, after apply | coating the adhesive composition for optical films mentioned above on a release sheet, the process of heat-processing is performed. Such a heat treatment step not only dries and removes the solvent in the coating film obtained by coating, but also serves to cross-link the above-mentioned pressure-sensitive adhesive composition for optical films. The temperature of the heat treatment is preferably 40 ° C. or higher and 150 ° C. or lower, more preferably 50 ° C. or higher and 130 ° C. or lower, and further preferably 80 ° C. or higher and 120 ° C. or lower. 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.

  In addition, 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 further preferably 10 seconds or more and 5 minutes or less. Preferably, it is 10 seconds or more and 2 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.

{Optical member}
According to one form of this invention, the optical member which has the adhesive layer for optical films mentioned above and the 1st optical film provided in one surface of the said adhesive layer is provided.

  Moreover, the optical member of this invention can further have glass or a 2nd optical film in the surface on the opposite side to the surface in which said 1st optical film of the adhesive layer of this invention was provided. 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 base treatment such as formation of 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)>
The optical member of the present invention preferably further includes at least one easy adhesion treatment layer between the first optical film and the optical film pressure-sensitive adhesive layer.

  As a more preferred embodiment, the optical member of the present invention has a first easy-adhesion treatment layer on the surface of the first optical film facing the pressure-sensitive adhesive layer for the optical film, and the optical film A second easy adhesion treatment layer is provided on the surface of the pressure-sensitive adhesive layer facing the first 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.

  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.

  The material constituting the primer layer is preferably a material that forms a film having good cohesion with a member that contacts the primer layer and excellent 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. Of these, polyurethane resins and oxazoline group-containing polymers are 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.

<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 3 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.

  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 the like. 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, the measurement of the operation and physical properties is performed under the condition 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, thermometer, nitrogen gas inlet tube, and cooler, 99% by mass of n-butyl acrylate (manufactured by Nippon Shokubai Co., Ltd.), 4-hydroxybutyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.) ) 1% by mass, and 0.1% by mass of 2,2′-azobisisobutyronitrile (manufactured by Wako Pure Chemical Industries, Ltd.) as a polymerization initiator were charged together with 100% by mass of ethyl acetate and gently stirred. Nitrogen gas was introduced. After substituting with nitrogen gas, the liquid temperature in the flask was controlled at around 55 ° C. and a polymerization reaction was performed for 5 hours to prepare a solution of a (meth) acrylate copolymer (A1) having a weight average molecular weight (Mw) of 1.9 million. .

[Preparation of Production Examples 2 to 6 (Meth) acrylate Copolymers (A2) to (A6)]
The same operation as in Production Example 1 was carried out except that the type and composition ratio of each monomer forming the (meth) acrylate copolymer were changed as shown in Table 1 below, and the (meth) acrylate copolymer was obtained. Solutions of (A2) to (A6) were prepared. The respective weight average molecular weights (Mw) are also shown in Table 1.

  In addition, the measurement of the weight average molecular weight (Mw) in each manufacture example mentioned above was performed in accordance with the following method.

(Measurement of weight average molecular weight (Mw))
The weight average molecular weight of each (meth) acrylate copolymer prepared in each of the production examples described above was measured by GPC (gel permeation chromatography).
・ 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.

<Example 1>
[Preparation of pressure-sensitive adhesive composition for optical film]
The solid content of the (meth) acrylate copolymer (A1) solution obtained in Production Example 1 is 100% (w / w) (that is, 100 parts by weight of the (meth) acrylate copolymer (A1)). Perloyl (registered trademark) TCP (manufactured by NOF Corporation) as oxide (B) 2.5 parts by mass, Takenate (registered trademark) D110-N (trixylylene diisocyanate tri) as crosslinking agent (C) other than peroxide 75 wt% ethyl acetate solution of methylolpropane adduct, number of isocyanate groups in one molecule: 3, Mitsui Chemicals Co., Ltd.) 0.1 parts by mass (in terms of active ingredient), and KBM-403 as silane coupling agent (D) (3-Glycidoxypropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd.) 0.1 parts by mass was mixed, and the solution of the pressure-sensitive adhesive composition for optical film of Example 1 (solid content) 5% (w / w)) was prepared.

(Formation of adhesive layer)
The solution of the pressure-sensitive adhesive composition for optical film obtained above was subjected to silicone treatment, and was a 38 μm thick polyethylene terephthalate (PET) film (Mitsubishi Chemical Polyester Film Co., Ltd., MRF38, without oligomer prevention layer). On one side, the pressure-sensitive adhesive layer after drying 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)
(Preparation of 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 was stretched until the total stretch ratio was 6 times while being immersed in an aqueous solution containing boric acid at 4% by mass at 4% by mass and potassium iodide at 10% by mass at 0.5%. Next, after washing by immersing in an aqueous solution containing potassium iodide at 30 ° C. and 1.5 mass% concentration for 10 seconds, drying was performed at 50 ° C. for 4 minutes to obtain a polarizer. An acrylic film (lactone-modified acrylic resin film) having a thickness of 20 μm was bonded to one side of the polarizer with a polyvinyl alcohol-based adhesive to produce a single-sided protective thin polarizing plate having a total thickness of 27 μm.

(Preparation of polarizing plate with adhesive layer)
On the polarizer side forming the pressure-sensitive adhesive layer of the polarizing plate obtained above, corona treatment was performed with a corona discharge amount of 80 [W · min / m ² ] to form an easy adhesion treatment layer. 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 with the optical member of Example 1, that is, the pressure-sensitive adhesive layer-attached polarizing plate. Produced.

<Examples 2-29 and Comparative Examples 1-6>
As shown in Table 2 below, the (meth) acrylate copolymer (A), peroxide (B), and crosslinking agent other than peroxide (C) constituting the pressure-sensitive adhesive composition for an optical film, and necessary Except that the silane coupling agent (D) and silicate oligomer (E) were changed according to the type and amount (blending amount), and the temperature and time of the heat treatment when forming the adhesive layer were changed. In the same manner as in Example 1, polarizing plates with pressure-sensitive adhesive layers corresponding to the respective examples and comparative examples were produced.

{Evaluation}
The following evaluation was performed with respect to the polarizing plate (sample) with each adhesive layer produced by said Example and comparative example. Each evaluation result is shown in Table 3.

<Durability>
The optical member produced by the said Example and the comparative example was cut out to 37-inch size, it was set as the sample, and it affixed on the alkali free glass (Corning company make, Eagle XG) of thickness 0.7mm using the 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 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 for 500 hours in an atmosphere of 60 ° C./95% RH (humidification test)
(3) After 30 minutes of standing in an environment of 85 ° C. and 30 minutes of standing in an environment of −40 ° C., one cycle was treated for 300 cycles (300 hours) in one cycle (heat shock (HS) test). .

Visual evaluation A: No change in appearance such as foaming, peeling, or no floating.
○: Slightly peeled off or foamed at the end, but no problem in practical use.
Δ: There is peeling or foaming at the end, but there is no practical problem unless it is a special use.
X: Remarkably peeled off at the end, causing practical problems.

<Reworkability>
Samples obtained by cutting the optical members produced in the above examples and comparative examples into a width of 25 mm and a length of 100 mm were designated as sample 1, and those obtained by cutting them into a length of 420 mm and a width of 320 mm were designated as sample 2 (three pieces produced). 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 A: All three sheets can be peeled off satisfactorily without adhesive residue and film breakage.
○: A part of the three films was broken, but was peeled off by peeling again.
Δ: All three films were broken, but were peeled off by peeling again.
X: Adhesive residue was generated on all three sheets, or the film was broken and could not be peeled even when peeled many times.

  As described above, the results of the adhesive force and the actual reworkability were comprehensively determined for the reworkability of the samples of the examples and comparative examples.

<Gel fraction>
Based on the heat treatment temperature and time described in each of the examples and comparative examples described above (see Table 2), a separately formed pressure-sensitive adhesive layer is sandwiched from both sides by a release-treated polyethylene terephthalate (PET) film. A sample having the structure described above was prepared and used as a gel fraction measurement sample.

  Each sample was weighed immediately after the heat treatment to obtain an initial weight W1. Then, each sample was immersed in an ethyl acetate solution and left in an environment of 23 ° C. and 55% RH for 1 week. Then, the insoluble matter was taken out, ethyl acetate was removed, the sample was weighed after drying, and the weight (W2) was measured. The gel fraction of each sample was determined by the following formula 1.

<Aging-less>
When the gel fraction of the pressure-sensitive adhesive layer immediately after drying is a certain region or more, there is no concern about dents and durability, and aging treatment is not necessary (referred to as “aging-free”).

For this reason, based on the gel fraction of each sample measured by the method mentioned above, it judged on the following reference | standard and evaluated the necessity of the aging process of each sample.
○: Gel fraction 65% or more No impact on dents, workability and durability; no aging treatment required.
Δ: Gel fraction 40% or more and less than 65% No effect on dents; no aging treatment required.
X: Less than 40% of gel fraction There is concern about dents, workability deterioration, and durability deterioration; aging treatment is necessary.

<Oligomer contamination>
The polyethylene terephthalate (PET) film (thickness 38 μm, manufactured by Mitsubishi Chemical Polyester Film Co., Ltd., MRF38) without the oligomer-preventing layer with the pressure-sensitive adhesive layer formed in each Example and Comparative Example described above is shown in Table 2. It was applied to the coating line for 24 hours under the heat treatment temperature of the examples and comparative examples. When each film sample was heat-treated while being conveyed, the precipitation of the PET oligomer on the guide roll on the line was visually confirmed according to the following criteria.
◯: No PET oligomer was deposited on the guide roll.
Δ: There is a slight amount of PET oligomer precipitate on the guide roll.
X: A large amount of PET oligomer is deposited on the guide roll.

<Adhesive chipping property>
About the polarizing plate with the adhesive layer produced in each of the above-mentioned Examples and Comparative Examples (one piece) punched into a square having a side length of 100 mm with an automatic cutting machine NZ-600 manufactured by Sugano Seiki Seisakusho From the above, the chipping resistance was evaluated according to the following criteria.
◯: Depth of glue missing from the end is less than 100 μm.
(Triangle | delta): The paste chipping depth from an edge part is 100 micrometers or more and less than 300 micrometers.
X: Depth of glue missing from the end is 300 μm or more.

As is clear from Table 3 above, the polarizing plates with pressure-sensitive adhesive layers (Examples 1 to 29) using the pressure-sensitive adhesive composition for optical films of the present invention are all in harsh environments (high temperature, high humidity, It was found that both durability in heat shock and reworkability that allows the optical film to be easily peeled off from the liquid crystal panel can be achieved. Moreover, when the optical film pressure-sensitive adhesive composition according to the present invention is used, the liquid crystal panel is hardly contaminated. It was found that it was greatly suppressed. Furthermore, when the pressure-sensitive adhesive composition for optical films according to the present invention is used, when manufacturing a pressure-sensitive adhesive layer or when manufacturing an optical member or the like, it has excellent handling properties in terms of a manufacturing process that does not require aging. Also found to have.

Claims (21)

A pressure-sensitive adhesive composition for an optical film comprising a (meth) acrylate copolymer (A), a peroxide (B), and a crosslinking agent (C) other than a peroxide,
The content of the peroxide (B) is more than 2.0 parts by mass and 10 parts by mass or less with respect to 100 parts by mass of the (meth) acrylate copolymer (A).
The crosslinking agent (C) other than the peroxide does not contain a blocked isocyanate compound,
An adhesive composition for optical films. The (meth) acrylate copolymer (A) comprises: component (a1); and at least one of component (a2) and component (a3);
The component (a1) is a structural unit derived from an alkyl (meth) acrylate monomer, the component (a2) is a structural unit derived from a (meth) acrylate monomer having a hydroxyl group, and the component (a3) is It is a structural unit derived from a monomer other than the alkyl (meth) acrylate monomer and the (meth) acrylate monomer having a hydroxyl group.
The pressure-sensitive adhesive composition for an optical film according to claim 1.   The (meth) acrylate copolymer (A) contains 80% by mass or more of the component (a1) with respect to 100% by mass of the total amount of the structural units constituting the (meth) acrylate copolymer (A). The optical film pressure-sensitive adhesive composition according to claim 1, comprising .99 mass% or less.   The said (meth) acrylate copolymer (A) is 0.01 mass% of said components (a2) with respect to 100 mass% of whole quantity of the structural unit which comprises the said (meth) acrylate copolymer (A). The optical film pressure-sensitive adhesive composition according to claim 2 or 3, comprising 5% by mass or less.   The said (meth) acrylate copolymer (A) exceeds the said component (a3) with respect to 100 mass% of the whole quantity of the structural unit which comprises the said (meth) acrylate copolymer (A), and exceeds 0 mass%. The optical film pressure-sensitive adhesive composition according to any one of claims 2 to 4, comprising 15% by mass or less.   Content of crosslinking agents (C) other than the said peroxide is 0.001 mass part or more and 2 mass parts or less with respect to 100 mass parts of said (meth) acrylate copolymers (A). The adhesive composition for optical films of any one of -5.   The pressure-sensitive adhesive composition for an optical film according to any one of claims 1 to 6, wherein the peroxide (B) has a one-minute half-life temperature of 80 ° C or higher and 125 ° C or lower.   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 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 30000 or less.   The crosslinking agent (C) other than the peroxide includes at least one 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. Item 12. The pressure-sensitive adhesive composition for an optical film according to any one of items 1 to 11.   The adhesive layer for optical films formed from the adhesive composition for optical films of any one of Claims 1-12. The pressure-sensitive adhesive layer for an optical film according to claim 13,
A first optical film provided on one surface of the pressure-sensitive adhesive layer;
An optical member.   The optical member according to claim 14, further comprising glass or a second optical film on a surface opposite to the surface on which the first optical film of the pressure-sensitive adhesive layer is provided.   The optical member according to claim 14 or 15, further comprising at least one easy adhesion treatment layer between the first optical film and the optical film pressure-sensitive adhesive layer. On the surface of the first 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 16, further comprising a second easy-adhesion treatment layer on a surface of the pressure-sensitive adhesive layer for the optical film that faces the first optical film.   The optical member according to any one of claims 14 to 17, wherein the first optical film is a polarizing plate.   An image display device using at least one optical member according to any one of claims 14 to 18.   The optical film pressure-sensitive adhesive composition according to any one of claims 1 to 12, comprising applying the pressure-sensitive adhesive composition for an optical film onto a release-treated release sheet, followed by heat treatment to cause a crosslinking reaction. Layer manufacturing method.   The manufacturing method of the adhesive layer for optical films of Claim 20 whose temperature of the said heat processing is 80 degreeC or more and 120 degrees C or less.