JP2017095654A - Adhesive for optical film, adhesive layer, optical member and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive for optical film, an adhesive layer, an optical member and an image display device excellent in adhesive force to an optical film or the like without generating peeling or floating even when holding a laminated film in a deformation state for a long time or repeatedly bending it.SOLUTION: There is provided an adhesive for optical film containing a (meth)acrylic ester copolymer (A), which contains (a1) a constitutional unit derived from an alkyl(meth)acrylic acid ester monomer of 9.9 mass% to 99.9 mass%, (a2) a constitutional unit derived from a macro monomer having a polymerizable functional group of 0.1 mass% to 15 mass%, (a3) a constitutional unit derived from a functional group-containing monomer which is a (meth)acrylic acid derivative monomer without having a plurality of radical polymerizable functional groups of 0 mass% to 20 mass% and (a4) a constitutional unit derived from a (meth)acrylic acid ester monomer other than the (a1), the (a2) and the (a3) of 0 mass% to 90 mass%, wherein the total amount of constitutional units derived from the (a1), the (a2), the (a3) and the (a4) is 100 mass%, glass transition temperature of the (meth)acrylic acid ester copolymer (A) is -70°C to -57°C and the weight average molecular weight is over 1,000,000 to 2,500,000 or less.SELECTED DRAWING: None

Description

  The present invention relates to an optical film pressure-sensitive adhesive, a pressure-sensitive adhesive layer, an optical member, and an image display device.

  Currently, flat display panels such as liquid crystal display panels (LCD) and plasma display panels (PDP) are mainly used as display panels. On the surface of the flat display panel, a laminate in which a plurality of films are usually laminated is bonded. For example, in an LCD, an optical film such as a polarizing plate, a retardation plate, a viewing angle widening film, and a brightness improving film is usually laminated on the surface of a liquid crystal panel. And each layer which comprises a planar display panel is bonded together by the adhesive layer normally formed with various adhesives.

  On the other hand, in addition to the flat display, a curved display or a flexible display has been demanded from the variety of design and usage. An organic electroluminescence panel (OLED) is mainly used for a curved display or a flexible display.

  In addition to the optical properties and durability required for conventional flat display panels, the optical film laminate used for this curved display or flexible display is laminated with an optical film and an adhesive layer or adhesive layer. Thus, it is required that the optical film is not peeled off or lifted even if it is held for a long time or subjected to a bending test.

  Patent Document 1 discloses a copolymer obtained by polymerizing a macromonomer having a (meth) acryloyl group, having a glass transition temperature of 40 ° C. or higher and a number average molecular weight (Mn) of 200 or more and 20,000 or less, and an epoxy. A pressure-sensitive adhesive composition containing a silane compound having a functional group that reacts with a group is disclosed.

  Patent Document 2 discloses a pressure-sensitive adhesive composition in which a pressure-sensitive adhesive polymer containing a macromonomer and polyisocyanate are mixed at a mass ratio of 10/90 or more and 90/10 or less.

  Patent Document 3 discloses that (meth) acrylic monomers are 94% by weight or more and 98.9% by weight or less, macromonomer 1% by weight or more and 5% by weight or less, carboxyl group, amino group, amide group, hydroxyl group or acetoacetyl. A pressure-sensitive adhesive composition containing 0.1% by weight or more and 1% by weight or less of an acrylic monomer containing any of the groups and having a gel fraction of 55% or more and 80% or less is disclosed.

  In Patent Document 4, a macromonomer having a glass transition temperature of 0 ° C. or higher and 160 ° C. or lower, a (meth) acrylic acid ester having an alkyl having 4 to 12 carbon atoms, and a monomer having a functional group are polymerized. A re-peeling pressure-sensitive adhesive composition in which a graft copolymer is crosslinked with a crosslinking agent having an isocyanurate skeleton is disclosed.

  Patent Document 5 discloses a weight average molecular weight obtained by copolymerizing 0.1% by weight to 10% by weight of a (meth) acrylic monomer having a crosslinkable functional group and 0.1% by weight to 30% by weight of a macromonomer. Discloses a laminate having a pressure-sensitive adhesive layer containing an acrylic polymer having a molecular weight of 50,000 or more and less than 400,000.

  Patent Document 6 discloses a pressure-sensitive adhesive composition containing a polymer having a hydroxyl group, which essentially comprises a macromonomer having a glass transition temperature of −100 ° C. or higher and lower than 30 ° C.

JP-A-10-140122 JP 2010-037431 A JP 2010-150400 A JP 2011-052117 A JP 2013-018227 A International Publication No. 2014/003173

  However, the pressure-sensitive adhesive composition described in Patent Documents 1 to 6 has a problem that it cannot satisfy the durability (bending resistance) at the time of bending in a temperature range where a curved display or a flexible display is used. It was.

  As described above, in the conventional adhesive, in addition to the optical characteristics and durability required for the flat display panel, the optical film is not deformed or lifted even if it is held for a long time or repeatedly bent. It could not meet the demand.

  Therefore, the present invention is excellent in adhesive strength to optical films and the like, and is hardly peeled off or floated even when held for a long time or repeatedly bent in a deformed state of the bonded film, and is an optical film pressure-sensitive adhesive. An object of the present invention is to provide an adhesive layer, an optical member, and an image display device.

  The present inventors have conducted intensive research to solve the above problems.

  As a result, the pressure-sensitive adhesive for optical films containing the (meth) acrylic acid ester copolymer (A), wherein the (meth) acrylic acid ester copolymer (A) is (a1) alkyl (meth) acrylic. Structural unit derived from acid ester monomer 9.9 mass% or more and 99.9 mass% or less; (a2) Structural unit derived from macromonomer having a polymerizable functional group 0.1 mass% or more and 15 mass% or less; (a3 ) A structural unit derived from a functional group-containing monomer which is a (meth) acrylic acid derivative monomer having no plurality of radically polymerizable functional groups; 0 mass% or more and 20 mass% or less; (a4) (a1), (a2) and A structural unit derived from a (meth) acrylic acid ester monomer other than (a3) 0 mass% or more and 90 mass% or less; and derived from the above (a1), (a2), (a3) and (a4) The total amount of the constituent units is 100% by mass, the glass transition temperature of the (meth) acrylic acid ester copolymer is −70 ° C. or higher and −57 ° C. or lower, and the weight average molecular weight exceeds 1,000,000. The present invention has been completed by finding that the above object can be achieved by providing a pressure-sensitive adhesive for optical films, a pressure-sensitive adhesive layer, an optical member, and an image display device that are 2.5 million or less.

  Adhesive for optical films, etc., adhesive film for optical films, which hardly peels off or floats even when held for a long time or repeatedly bent in a deformed state of the bonded film, as well as using the same An adhesive layer, an optical member, and an image display device can be provided.

It is a figure which shows the layer structure of the optical film which has a protective layer and a conductive layer.

  Hereinafter, embodiments for carrying out the present invention will be described in detail. In addition, this invention is not limited only to the following embodiment. In addition, the dimensional ratios in the drawings are exaggerated for convenience of explanation, and may be different from the actual ratios. In this specification, “weight” and “mass”, “wt%” and “mass%” are treated as synonyms. Unless otherwise specified, measurements such as operation and physical properties are performed under conditions of room temperature (20 ° C. to 25 ° C.) / Relative humidity of 40% to 60%.

  In this specification, the bending resistance can be evaluated by a bending test (for example, high temperature, high temperature and high humidity, low temperature). Specifically, “high temperature” in the bending test is 70 ° C. or higher, 80 ° C. or higher, or 85 ° C. or higher. The upper limit is 110 ° C. or lower or 105 ° C. or lower. In addition, “high temperature and humidity” in the bending test means that the temperature is 40 ° C. to 85 ° C. or 55 ° C. to 85 ° C. and the relative humidity is 85% RH to 98% RH or 85% RH to 95% RH. It points to something. The “low temperature” in the bending test is 0 ° C. or lower or −20 ° C. or lower, and the lower limit is −40 ° C. or higher.

  Moreover, in this specification, durability can be evaluated by a durability test (for example, a high temperature test, a high temperature and high humidity test, a heat shock test). In this case, “high temperature” and “high temperature and humidity” are defined in the same manner as the above bending test, and the heat shock test is an endurance test by repeating “high temperature” and “low temperature”. Is 0 ° C. or lower, −20 ° C. or lower, or −40 ° C. or lower, and the lower limit is −50 ° C. or higher, or −45 ° C. or higher. Although there is no restriction | limiting in particular also in the repetition frequency, It is about 100 times or more and 1000 times or less.

  In this specification, “(meth) acrylic acid ester monomer” is a general term for acrylic acid ester monomers and methacrylic acid ester monomers. Similarly, a compound containing (meth) such as (meth) acrylic acid is a generic term for a compound having “meta” in the name and a compound not having “meta”. For this reason, "(meth) acryl" includes both acrylic and methacrylic. “(Meth) acrylate monomer” includes both acrylate monomers and methacrylate monomers. “(Meth) acrylic acid” includes both acrylic acid and methacrylic acid.

<Adhesive for optical film>
The pressure-sensitive adhesive for optical films according to the present invention (hereinafter also simply referred to as “pressure-sensitive adhesive”) comprises the following (meth) acrylic acid ester copolymer (A), preferably a cross-linking agent (B) or a silane cup. It further contains at least one of the ring agent (C).

  Hereinafter, the components (A) to (C) will be described.

[(Meth) acrylic acid ester copolymer (A)]
The (meth) acrylic acid ester copolymer (A) (hereinafter also referred to as “copolymer (A)”) is a structural unit derived from (a1) an alkyl (meth) acrylic acid ester monomer of 9.9% by mass to 99%. 0.9 mass% or less; (a2) a structural unit derived from a macromonomer having a polymerizable functional group 0.1 mass% or more and 15 mass% or less; (a3) not having a plurality of radically polymerizable functional groups (meth) A structural unit derived from a functional group-containing monomer that is an acrylic acid derivative monomer 0% by mass or more and 20% by mass or less; (a4) derived from a (meth) acrylic acid ester monomer other than the above (a1), (a2), and (a3) The total amount of the structural units derived from the above (a1), (a2), (a3) and (a4) is 100% by mass, and the (meth) Acry The glass transition temperature of the phosphate ester copolymer is -70 ° C or higher and -57 ° C or lower, and the weight average molecular weight is more than 1,000,000 and not more than 2.5 million.

  Thus, in the present invention, the glass transition temperature of the copolymer (A) is lowered (specifically, −70 ° C. or higher and −57 ° C. or lower) and the weight average molecular weight is increased (specifically. Is characterized in that the weight average molecular weight is more than 1 million and not more than 2.5 million).

  In the present invention, the weight average molecular weight of the copolymer (A) is more than 1 million and 2.5 million or less. When the weight average molecular weight is 1,000,000 or less, the durability and bending resistance of the pressure-sensitive adhesive are lowered. On the other hand, when the weight average molecular weight exceeds 2.5 million, the viscosity of the copolymer solution increases, so that the workability (such as coating property) of the pressure-sensitive adhesive decreases. Furthermore, the weight average molecular weight of the copolymer (A) is preferably more than 1,200,000 and not more than 2.5 million from the viewpoint of bending resistance at room temperature, and more than 1,200,000 from the viewpoint of bending resistance at low temperature. More preferably, it is 2.2 million or less. That is, the preferable form of this invention is an adhesive for optical films whose weight average molecular weight of the said copolymer (A) exceeds 1,200,000. In addition, in this specification, a weight average molecular weight is the value measured by the method shown in an Example.

  The (meth) acrylic acid ester copolymer (A) according to the present invention has a glass transition temperature of −70 ° C. or higher and −57 ° C. or lower. When the glass transition temperature is less than -70 ° C, the elastic modulus at a high temperature is lowered, and peeling or foaming may occur. On the other hand, when the glass transition temperature exceeds −57 ° C., the bending resistance is lowered (particularly under high temperature and high humidity). Furthermore, the upper limit of the glass transition temperature of the copolymer (A) is preferably less than −60 ° C. from the viewpoint of bending resistance at low temperatures. That is, the preferable form of this invention is an adhesive for optical films whose said glass transition temperature is -70 degreeC or more and less than -60 degreeC. The lower limit of the glass transition temperature of the copolymer (A) is preferably −69 ° C. or higher, more preferably −67 ° C. or higher, from the viewpoint of durability at high temperatures.

  According to the preferable form of this invention, the (meth) acrylic acid ester copolymer (A) contains a hydroxyl group. When such a copolymer (A) is contained in the pressure-sensitive adhesive, the adhesion to a polar substrate is improved, and the crosslinking density is improved when used in combination with an isocyanate-based crosslinking agent, and durability (particularly under high temperature and high humidity) is improved. Improves. That is, when the copolymer (A) contains a hydroxyl group that reacts with an isocyanate compound that is a crosslinking agent, the pressure-sensitive adhesive forms a crosslinked structure and is preferable because both adhesiveness and durability can be achieved.

  That is, the preferable form of this invention is an adhesive for optical films in which the said (meth) acrylic acid ester copolymer (A) contains a hydroxyl group.

((A1) alkyl (meth) acrylic acid ester monomer)
The (meth) acrylic acid ester copolymer (A) of the present invention contains a structural unit derived from an alkyl (meth) acrylic acid ester monomer (hereinafter also referred to as component (a1) or simply (a1)). By including such a component in the pressure-sensitive adhesive of the present invention, it is considered that it has the significance of ensuring adhesiveness and basic characteristics.

  (A1) A component will not be restrict | limited especially if the alkyl group is introduce | transduced into the ester site | part of (meth) acrylic acid ester.

  The number of carbon atoms of the alkyl group is not particularly limited, but is preferably 1 to 20 carbon atoms. From the viewpoint of compatibility with the glass transition temperature of the copolymer (A) and the crosslinking agent, the number of carbon atoms is 2 or more. 18 or less is more preferable, 3 to 16 carbon atoms is even more preferable, and 4 to 12 carbon atoms is particularly preferable. The alkyl group may be linear, branched or cyclic, but is preferably linear or branched from the viewpoint of lowering the glass transition temperature of the copolymer (A). . In the case of an annular shape, the number of carbon atoms is 3 or more. That is, the preferable form of this invention is an adhesive for optical films whose (a1) alkyl (meth) acrylic acid ester monomer is C1-C18 of an alkyl group.

  The component (a1) is typically represented by the following chemical formula 1.

Here, in the above chemical formula 1,
R ₁ is a hydrogen atom or a methyl group,
R ₂ is the above alkyl group.

  Such alkyl group is not particularly limited, but is methyl group, ethyl group, propyl group, isopropyl group, butyl group, sec-butyl group, tert-butyl group, isobutyl group, amyl group, isoamyl group, tert-amyl 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, tert-heptyl group, n-octyl Group, isooctyl group, tert-octyl group, 2-ethylhexyl group, nonyl group, isononyl group, decyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, etc. . In particular, from the viewpoint of adhesiveness, a methyl group, a butyl group, a 2-ethylhexyl group, an n-hexyl group, a nonyl group, and an isononyl group are preferable.

  As the component (a1), those having a glass transition temperature of the homopolymer in the range of −70 ° C. or higher and −30 ° C. or lower from the viewpoint that the glass transition temperature of the copolymer (A) can be easily controlled in a desired range. Preferably, those in the range of −70 ° C. or higher and −50 ° C. or lower are preferable.

  Therefore, as the alkyl (meth) acrylic acid ester monomer, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (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, and the like. Among these, 2-ethylhexyl (meth) acrylate is particularly preferable from the viewpoint of easily controlling the glass transition temperature of the copolymer (A) within a desired range. These can be used alone or in admixture of two or more.

  As a commercial item, 2EHA, BA (above, Nippon Shokubai Co., Ltd. product) etc. are suitable.

  The content of the structural unit derived from the component (a1) in the copolymer (A) is when the total amount of structural units derived from the components (a1), (a2), (a3) and (a4) is 100% by mass. 9.9 mass% or more and 99.9 mass% or less. When the content is less than 9.9% by mass, since the proportion of components other than (a1) in the copolymer (A) increases, it is difficult to balance adhesiveness, durability, and bending resistance. On the other hand, when the content exceeds 99.9% by mass, it becomes difficult to impart cohesive force to the pressure-sensitive adhesive, and the adhesiveness is lowered. Furthermore, the lower limit of the content is preferably 50% by mass or more from the viewpoint of durability and adhesiveness, more preferably 60% by mass or more, and still more preferably from the viewpoint of bending resistance at low temperatures. Is 70% by mass or more.

  In addition, the upper limit of the content is preferably 95% by mass or less, more preferably 90% by mass or less, from the viewpoint of bending resistance at high temperatures. That is, the preferable form of this invention is an adhesive for optical films whose structural unit derived from (a1) alkyl (meth) acrylic acid ester monomer is 60 mass% or more and 90 mass% or less.

((A2) Macromonomer having a polymerizable functional group)
The (meth) acrylic acid ester copolymer (A) of the present invention contains a structural unit derived from a macromonomer having a polymerizable functional group (hereinafter also referred to as (a2) component or simply (a2)). The component (a2) is a high molecular weight monomer having a polymerizable functional group (ethylenically unsaturated group), and has a polymer chain portion and a polymerizable functional group.

  Bending resistance improves because the copolymer (A) polymerized using such a monomer is contained in the pressure-sensitive adhesive. The mechanism is considered to vary depending on the glass transition temperature of the polymer chain portion of the macromonomer. Specifically, when the glass transition temperature of the polymer chain portion is high, the polymer chain portion forms a hard segment in the pressure-sensitive adhesive, thereby causing cohesive force in the pressure-sensitive adhesive. Thereby, it is thought that bending tolerance improves because the adhesive force to a base material increases. On the other hand, when the glass transition temperature of the polymer chain portion of the macromonomer is low, the pressure-sensitive adhesive becomes flexible and the followability to the base material is improved, so that the bending resistance is considered to be improved. In addition, the said mechanism is based on estimation and this invention is not restrict | limited to the said mechanism at all.

  As the polymerizable functional group of the component (a2), a group having an ethylenically unsaturated double bond (ethylenically unsaturated group) is preferable. Specifically, at least one selected from the group consisting of a vinyl group, an allyl group, a (meth) acryloyl group, and a propenyl group is preferable. The polymerizable functional group is preferably present at the end of the macromonomer, and more preferably present only at one end of the macromonomer from the viewpoint of stability during polymerization. However, the polymerizable functional group may exist as a side chain of the macromonomer, or may exist at both ends of the chain of the macromonomer.

  The polymer chain part of the component (a2) is methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, alkyl (meth) acrylate, stearyl (meth) acrylate, n-butyl (meth) acrylate, It is a (co) polymer whose main structural unit is a repeating unit derived from isobutyl (meth) acrylate, t-butyl (meth) acrylate, styrene, acrylonitrile, hydroxy (meth) acrylate, ethylhexyl acrylate, dimethylsiloxane, or the like. Is preferred. These polymer chain portions may be composed of a single repeating unit, or may be composed of a plurality of repeating units. Further, when the polymer chain is a copolymer composed of a plurality of repeating units, the repeating form is not limited, and any of an alternating copolymer, a random copolymer, and a block copolymer may be used.

  The component (a2) is typically represented by the following chemical formula 2.

Here, in the above chemical formula 2, R ₃ represents a hydrogen atom or a methyl group, and X represents a single bond or a divalent linking group.

  Examples of the divalent linking group include a linear, branched or cyclic alkylene group, an aralkylene group, and an arylene group. These may further have a substituent such as a hydroxy group or a cyano group. The alkylene group preferably has 1 to 10 carbon atoms, more preferably 1 to 4 carbon atoms. Examples of the alkylene group include a methylene group, an ethylene group, a trimethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, an octylene group, a decylene group, and a cyclohexylene-1,4-dimethylene group. Among these, a methylene group, an ethylene group, a propylene group, and the like are preferable. The carbon number of the aralkylene group is preferably 7 or more and 13 or less. Examples of the aralkylene group include a benzylidene group and a cinnamylidene group. The arylene group preferably has 6 to 12 carbon atoms. Examples of the arylene group include a phenylene group, a cumenylene group, a mesitylene group, a tolylene group, and a xylylene group. Among these, a phenylene group is preferable.

In the divalent linking group, —NR ₂ —, —COO—, —OCO—, —O—, —S—, —SO ₂ NH—, —NHSO ₂ —, —NHCOO—, —OCONH— Alternatively, a group derived from a heterocyclic ring, or the like may be interposed as a linking group. R ₂ is hydrogen or an alkyl group such as a methyl group, an ethyl group, or a propyl group.

  In the above chemical formula 2, Y is methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, alkyl (meth) acrylate, stearyl (meth) acrylate, n-butyl (meth) acrylate, Polymer obtained by homopolymerizing or copolymerizing one or more monomers selected from isobutyl (meth) acrylate, t-butyl (meth) acrylate, styrene, acrylonitrile, hydroxy (meth) acrylate, and ethylhexyl acrylate, or organic This represents a polysiloxane (polyorganosiloxane) in which a group is bonded to a silicon atom. Among them, Y is a polymer obtained by homopolymerizing methyl (meth) acrylate, styrene, n-butyl (meth) acrylate or isobutyl (meth) acrylate, a polymer obtained by copolymerizing acrylonitrile and styrene, or polyorganosiloxane. It is preferable.

  Furthermore, from the viewpoint of durability at high temperatures, Y is particularly preferably a polymer obtained by homopolymerizing methyl (meth) acrylate, styrene or isobutyl (meth) acrylate, or a polymer obtained by copolymerizing acrylonitrile and styrene. Alternatively, from the viewpoint of bending resistance at low temperatures, Y is preferably a polyorganosiloxane, particularly preferably polydimethylsiloxane. In addition, as long as it does not affect the performance of an adhesive, a part of methyl group of polydimethylsiloxane may be substituted by organic groups (ethyl group, phenyl group, etc.) other than a hydrogen atom or a methyl group.

  The polydimethylsiloxane can be obtained by hydrolyzing and condensing dimethyldialkoxysilane such as dimethyldimethoxysilane and dimethyldiethoxysilane. In this case, an organic group other than a methyl group can be introduced into polydimethylsiloxane by using together an alkoxysilane having an organic group other than a methyl group (for example, diethyldiethoxysilane). In addition to the dialkoxy silane compound, a small amount of trialkoxy silane compound may be added.

  The number average molecular weight (Mn) of the component (a2) is preferably in the range of 2,000 to 20,000, more preferably in the range of 2,000 to 10,000, More preferably, it is in the range of no less than 000 and no more than 8,000. If the number average molecular weight (Mn) is 2,000 or more, the performance of the pressure-sensitive adhesive can be improved even if the amount of the component (a2) added when synthesizing the copolymer (A) is small. . On the other hand, if it is 20,000 or less, the viscosity of the pressure-sensitive adhesive is low and the workability is good. The value of the number average molecular weight (Mn) can be controlled by appropriately selecting the amounts of a chain transfer agent and a polymerization initiator added to the polymerization system. In addition, in this invention, the value of polystyrene conversion measured by GPC (gel permeation chromatography) method shall be employ | adopted for the number average molecular weight (Mn) of a macromonomer.

  The glass transition temperature of the polymer chain part of the component (a2) is preferably 50 ° C. or higher and 110 ° C. or lower. In such a range, the polymer chain portion forms a hard segment in the pressure-sensitive adhesive, so that cohesive force is generated in the pressure-sensitive adhesive. As a result, the adhesiveness of the adhesive to the base material is improved, and excellent bending resistance can be exhibited. Or as for the glass transition temperature of the polymer chain part of (a2) component, -40 degreeC or more and -125 degrees C or less are preferable. In such a range, since the component (a2) is a macromonomer having a polyorganosiloxane structure, compatibility with an acrylic resin can be ensured and low temperature characteristics can be satisfied. Moreover, when it exists in such a range, since an adhesive shows a softness | flexibility in a wide temperature range, the followable | trackability to a base material is favorable and can express the outstanding bending tolerance (especially under low temperature). .

  As the component (a2), either a synthetic product or a commercial product may be used. When the component (a2) is synthesized, there is no particular limitation on the synthesis method. For example, (1) a polymer chain (living polymer anion) constituting a macromonomer is produced by living anion polymerization, and methacrylic acid chloride or the like acts on this. (2) In the presence of a chain transfer agent such as mercaptoacetic acid, a radical polymerizable monomer such as methyl methacrylate is polymerized to obtain an oligomer having a carboxyl group at the terminal, and this is then converted to glycidyl methacrylate and the like. (3) In the presence of an azo polymerization initiator containing a carboxyl group, a radical polymerizable monomer such as methyl methacrylate is polymerized to obtain an oligomer having a carboxyl group at the terminal, and then macromolecules with glycidyl methacrylate. Any method such as a method for monomerization can be used.

  By producing a macromonomer using the method as described above, for example, the following groups are introduced as the divalent linking group represented by X in Formula 2 above.

  Examples of commercially available products of component (a2) include macromonomers (product names: 45% AA-6 (AA-6S), AA, whose terminal is a methacryl group and whose polymer chain portion is polymethyl methacrylate (PMMA). -6; manufactured by Toagosei Co., Ltd.), a macromonomer whose polymer chain part is polystyrene (product name: AS-6S, AS-6; manufactured by Toagosei Co., Ltd.), and a copolymer of styrene / acrylonitrile whose polymer chain part is The macromonomer (product name: AN-6S; manufactured by Toagosei Co., Ltd.), the polymer chain part is a polybutylacrylate macromonomer (product name: AB-6; manufactured by Toagosei Co., Ltd.), and the polymer chain part is polyisobutyl. Macromonomer that is methacrylate (product name: AW-6S; manufactured by Toagosei Co., Ltd.), polymer chain portion is polydimethylsiloxy Down in a macro monomer (product name: AK-5; manufactured by Toagosei Co., Ltd.) and the like can be used. In addition, these macromonomers may be used independently and may be used together 2 or more types.

  Content of the structural unit derived from the component (a2) in the copolymer (A) is when the total amount of structural units derived from the components (a1), (a2), (a3) and (a4) is 100% by mass. 0.1 mass% or more and 15 mass% or less. When the said content is less than 0.1 mass%, the effect of (a2) component addition in adhesive performance is not seen. On the other hand, when the content exceeds 15%, it becomes difficult to balance adhesiveness, durability, and bending resistance, and transparency is also lowered.

  In the embodiment of the present invention, the upper limit of the content is preferably 8% by mass or less from the viewpoint of bending resistance at high temperature, and is preferably less than 5% by mass from the viewpoint of bending resistance at low temperature. In addition, the lower limit of the content is preferably 0.5% by mass or more, and more preferably 1% by mass or more from the viewpoint of obtaining the effect of component (a2) addition.

((A3) Functional group-containing monomer that is a (meth) acrylic acid derivative monomer having no radically polymerizable functional group)
In a preferred embodiment of the present invention, the (meth) acrylic acid ester copolymer (A) is a functional group-containing monomer (hereinafter referred to as (a3)) which is a (meth) acrylic acid derivative monomer having no plural radical polymerizable functional groups. A constituent unit derived from a component or simply (also referred to as (a3)).

  The “(meth) acrylic acid derivative” refers to a compound obtained by using (meth) acrylic acid as a starting material, and is preferably (meth) acrylic acid ester or (meth) acrylamide.

  That is, the component (a3) has one of a methacryl group or an acryl group and one or more functional groups other than the (meth) acryl group, or a (meth) acrylate monomer or ( A meth) acrylamide monomer is preferred.

  Although the component (a3) is an optional component, it is combined with the component (a2) and is included in the pressure-sensitive adhesive of the present invention, so that it has an effect of improving adhesiveness, and the desired effect of the present invention is further improved. It can play efficiently.

  In addition, when the monomer which comprises a (meth) acrylic acid ester copolymer (A) corresponds to both (a1) component and (a3) component, it shall classify | categorize into (a3) component.

  The functional group contained in the component (a3) is preferably a functional group that reacts with the crosslinking agent when the crosslinking agent (B) is used, and more preferably a hydroxyl group, an acyl group, or an epoxy group. By including the copolymer (A) obtained by using such a functional group-containing monomer in the pressure-sensitive adhesive, the copolymer (A) is cross-linked with the cross-linking agent (B), and is durable at high temperatures. Is thought to improve. That is, in a preferred embodiment of the present invention, (a3) the functional group-containing monomer which is a (meth) acrylic acid derivative monomer having no radically polymerizable functional group has a hydroxyl group, an acyl group or an epoxy group (meth). It is an adhesive for optical films, which is an acrylic acid derivative monomer.

<< (a3-1) (Meth) acrylic acid ester monomer having hydroxyl group, acyl group or epoxy group >>
A (meth) acrylic acid ester monomer having a hydroxyl group, an acyl group or an epoxy group (hereinafter also referred to as a component (a3-1)) is typically represented by the following chemical formula 3.

Here, in the above chemical formula 3,
R ₄ is a hydrogen atom or a methyl group,
R ₅ is a single bond or a divalent organic group,
R ₆ is a hydroxyl group, an acyl group, or an epoxy group.

  The carbon number of the acyl group is not particularly limited, but is preferably 1 to 18 carbon atoms, more preferably 1 to 6 carbon atoms. The acyl group includes an acetoacetoxy group.

  Here, the divalent organic group is not particularly limited, but an alkylene group having 1 to 10 carbon atoms is preferable. The above-mentioned thing is mentioned similarly as a C1-C10 alkylene group. The alkylene group or the acyl group replaces at least one alkyl group having 1 to 8 carbon atoms, phenoxyalkyl group (carbon number of the alkyl group: 1 to 8 carbon atoms), phenyl group, or cyclohexyl group. You may have as a group. The alkyl group having 1 to 8 carbon atoms can be appropriately selected from the above.

  From the above, 4-hydroxybutyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, glycidyl (meth) acrylate, acetoacetoxyethyl (meth) acrylate, 2-hydroxymethyl (meth) acrylate, 2-hydroxypropyl (meth) ) Acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 1,4-cyclohexanedimethanol (meth) monoacrylate and the like are preferable, and 4-hydroxybutyl (meth) acrylate is particularly preferable from the viewpoint of adhesiveness. 2-hydroxyethyl (meth) acrylate, glycidyl (meth) acrylate, acetoacetoxyethyl (meth) acrylate, and the like are preferable. These can be used alone or in admixture of two or more.

  Commercially available products include 2HEA (above, Nippon Shokubai Co., Ltd.), 4HBA (above, Nihon Kasei Co., Ltd.), light ester HOA (N), light ester HOP-A (N), light acrylate HOB-A, epoxy Ester M-600A (above, Kyoeisha Chemical Co., Ltd.), CHDMMA (above, Nippon Kasei Chemical Co., Ltd.), GMA (Mitsubishi Gas Chemical Co., Ltd.), AAEM (above, Nihon Synthetic Chemical Industry Co., Ltd.) are suitable. is there.

<< (a3-2) (Meth) acrylamide monomer having hydroxyl group, acyl group or epoxy group >>
A (meth) acrylamide monomer having a hydroxyl group, an acyl group, or an epoxy group (hereinafter also referred to as a component (a3-2)) is typically represented by the following chemical formula 4.

Here, in the above chemical formula 4, R ₇ is a hydrogen atom or a methyl group, R ₈ is a single bond or a divalent organic group, R ₉ is a hydroxyl group, an acyl group, or an epoxy group, R ₁₀ is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms.

  The divalent organic group is not particularly limited, but is preferably an alkylene group having 1 to 10 carbon atoms. In addition, the alkylene group or the acyl group may have at least one alkyl group having 1 to 8 carbon atoms, a phenyl group, or a cyclohexyl group as a substituent.

  Examples of the alkyl group having 1 to 10 carbon atoms include methyl group, ethyl group, propyl group, isopropyl group, butyl group, sec-butyl group, tert-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, tert-heptyl group, n-octyl group, isooctyl group, tert-octyl group, A 2-ethylhexyl group, a nonyl group, an isononyl group, a decyl group, and the like are preferable.

  The carbon number of the acyl group is not particularly limited, but is preferably 1 to 18 carbon atoms, more preferably 1 to 6 carbon atoms. The acyl group includes an acetoacetoxy group.

  The alkylene group having 1 to 10 carbon atoms is a divalent substituent obtained by removing one hydrogen atom from the alkyl group having 1 to 10 carbon atoms.

  From the above, N- (2-hydroxyethyl) (meth) acrylamide, N- (2-hydroxypropyl) (meth) acrylamide, N- (2,2-dimethyl-β-hydroxyethyl) (meth) acrylamide, diacetone (Meth) acrylamide is preferred. Among these, N- (2-hydroxyethyl) (meth) acrylamide is particularly preferable from the viewpoint of improving adhesiveness. You may use these individually or in mixture of 2 or more types.

  As a commercial item, HEAA (trademark) (made by KJ Chemicals Co., Ltd.) and DAAM (made by Nippon Kasei Co., Ltd.) are suitable.

  In addition, the component (a3-1) and the component (a3-2) may be used alone or in combination. When the (a3-1) component and the (a3-2) component are mixed and used, the glass transition temperature can be kept low while maintaining good adhesion to the polar substrate by ensuring hydrophilicity. .

  The content of the structural unit derived from the component (a3) in the copolymer (A) is when the total amount of structural units derived from the components (a1), (a2), (a3) and (a4) is 100% by mass. 0 mass% or more and 20 mass% or less. When the content exceeds 20% by mass, the balance of adhesiveness, durability, and bending resistance deteriorates due to the increase in glass transition temperature and the degree of crosslinking. The lower limit of the content is preferably 0.1% by mass or more, and more preferably 2% by mass or more from the viewpoint of bending resistance at high temperatures. In addition, the upper limit of the content is preferably less than 15 parts by mass from the viewpoint of bending resistance at low temperatures.

((Meth) acrylic acid ester monomers other than (a4) (a1), (a2) and (a3))
The (meth) acrylic acid ester copolymer (A) of the present invention is a (meth) acrylic acid ester monomer other than the above (a1), (a2) and (a3) (hereinafter referred to as (a4) component, or simply (a4). )))-Derived structural units may be included.

  The component (a4) is not particularly limited as long as it is a (meth) acrylic acid ester monomer other than (a1), (a2), and (a3). From the viewpoint of lowering the glass transition temperature of the polymer (A), a (meth) acrylic acid ester monomer having an alkoxyalkyl group or an alkylene oxide group is preferred.

  The (meth) acrylic acid ester monomer having an alkoxyalkyl group or an alkylene oxide group is not particularly limited as long as it has an alkoxyalkyl group or an alkylene oxide structure in the (meth) acrylic acid ester molecule. By including such a component in the pressure-sensitive adhesive of the present invention, it is considered that the adhesiveness and durability are improved. Moreover, by including (a4) component, the bending tolerance at the time of low temperature can be provided, and a low temperature characteristic can be ensured, without reducing adhesiveness. However, since the component (a2) is contained in the pressure-sensitive adhesive of the present invention, the desired effect of the present invention can be exhibited even if the component (a4) is an optional component.

  The number of carbon atoms of the alkoxy moiety in the alkoxyalkyl group is not particularly limited, but may be from 1 to 20 carbon atoms from the viewpoint of improving adhesiveness and durability, and efficiently exhibiting the desired effect of the present invention. Preferably, it has 1 to 8 carbon atoms, more preferably 1 to 6 carbon atoms, still more preferably 1 to 4 carbon atoms. Specific examples of the alkoxy moiety having 1 to 20 carbon atoms are preferred.

  Further, the carbon number of the alkyl moiety in the alkoxyalkyl group is not particularly limited, but from the viewpoint of efficiently achieving the balance between improved adhesiveness and improved durability, and effectively achieving the desired effect of the present invention, the number of carbon atoms is 1 or more and 6 or more. Or less, and more preferably 1 to 4 carbon atoms.

  Further, the number of carbon atoms of the alkylene moiety in the alkylene oxide group is not particularly limited, but from the viewpoint of improving adhesiveness and durability, and efficiently exhibiting the desired effect of the present invention, the number of carbon atoms of 1 or more is preferable. The number of carbon atoms is more preferably 1 or more and 3 or less.

  A (meth) acrylic acid ester monomer having an alkoxyalkyl group or an alkylene oxide group is typically represented by the following chemical formula 5.

Here, in the above chemical formula 5, R ₁₁ is a hydrogen atom or a methyl group, and R ₁₂ is an alkoxyalkyl group or — (A—O) _n —X.

  Here, the alkoxyalkyl group is preferably a methoxyethyl group, an ethoxymethyl group, an ethoxyethyl group, a propoxyethyl group, a butoxyethyl group, a methoxypropyl group, or a methoxybutyl group.

  A is a methylene group, ethylene group, propylene group or butylene group, and n is preferably 1 or more and 10 or less, more preferably 1 or more and 4 or less.

  X is an alkyl group. The alkyl group may be linear or branched, and the number of carbon atoms is preferably 1 or more and 20 or less, more preferably 1 or more and 10 or less, and even more preferably 1 or more and 5 or less. It is especially preferable that it is 1 or more and 3 or less. Specific examples of such an alkyl group are those listed above, and a methyl group, an ethyl group, or a propyl group is particularly preferable.

  From the above, 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 (meth) acrylate, propoxy-diethylene glycol (meth) acrylate, methoxy-triethylene Glycol (meth) acrylate, 2-ethylhexyloxy-didiethylene glycol (meth) acrylate, methoxy- Triethylene glycol (meth) acrylate (n = 4 to 10), methoxy dipropylene glycol (meth) acrylate. These can be used alone or in admixture of two or more.

  Among these, from the viewpoint of efficiently exhibiting the desired effect of the present invention with improved adhesion and durability, 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, methoxy-triethylene glycol (meth) acrylate, 2-ethylhexyloxy -Diethylene glycol (meth) acrylate is more preferred. These can be used alone or in admixture of two or more.

  Commercially available products include AME (manufactured by Nippon Shokubai Co., Ltd.), light acrylate EC-A, light acrylate MTG-A, light acrylate EHDG-AT, light acrylate 130A, light acrylate DPM-A, (manufactured by Kyoeisha Chemical Co., Ltd.) ), Biscoat # 190, 2-MTA, MPE400A, MPE550A (manufactured by Osaka Organic Chemical Co., Ltd.) are suitable.

  The content of the structural unit derived from the component (a4) in the copolymer (A) is when the total amount of structural units derived from the components (a1), (a2), (a3) and (a4) is 100% by mass. 0 mass% or more and 90 mass% or less. When the content exceeds 90% by mass, the adhesiveness is lowered and the glass transition temperature is increased, and the balance of adhesiveness, durability, and bending resistance is deteriorated.

  Further, the upper limit of the content is preferably 49.9% by mass or less, more preferably 35% by mass or less from the viewpoint of durability and adhesiveness, and further more from the viewpoint of bending resistance at low temperatures. Preferably it is less than 30% by mass.

  Even if the structural unit derived from the component (a4) is a sufficiently small amount, for example, less than 5% by mass, since the component (a2) is essential, the desired effect of the present invention is sufficiently achieved. Can be made.

(Production of (meth) acrylic acid ester copolymer (A))
The method for producing the (meth) acrylic acid ester copolymer (A) is not particularly limited, and is a solution polymerization method, bulk polymerization method, emulsion polymerization method, suspension polymerization method, reverse phase suspension polymerization method, thin film polymerization method. Conventionally known methods such as spray polymerization can be used. Examples of the polymerization control method include adiabatic polymerization, temperature controlled polymerization, and isothermal polymerization. In the above polymerization method, it is preferable to use a polymerization initiator. As the polymerization initiator, either a thermal polymerization initiator or a photopolymerization initiator may be used. Alternatively, in addition to the method of initiating polymerization with a polymerization initiator, a method of initiating polymerization by irradiating with radiation, electron beam, ultraviolet light or the like can be employed. Among them, (i) a solution polymerization method using a thermal polymerization initiator or (ii) a bulk polymerization method using a photopolymerization initiator is preferable. Furthermore, since the molecular weight can be easily adjusted and the amount of impurities is small, the polymerization method (i) is particularly preferred. For example, ethyl acetate, toluene, methyl ethyl ketone or the like is used as a solvent, and the polymerization initiator is preferably 0.001 part by mass with respect to 100 parts by mass of the total amount of raw material monomers of the (meth) acrylic acid ester copolymer (A). More preferably, 0.01 parts by mass or more and 0.50 parts by mass or less are added, and the reaction is performed in a nitrogen atmosphere, for example, at a reaction temperature of 60 ° C. or more and 90 ° C. or less for 3 hours or more and 10 hours or less.

  Examples of thermal polymerization initiators 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- (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-methyl) Azo compounds such as propane) dihydrochloride, 2,2′-azobis [2-methyl-N- (2-hydroxyethyl) propionamide]; tert-butyl peroxypivalate, tert-butyl peroxybenzoate, tert-butyl Peroxy-2-ethylhexanoate, di-tert-butyl peroxide, cumene high B peroxide, benzoyl peroxide, organic peroxides such as tert- butyl hydroperoxide; hydrogen peroxide, ammonium persulfate, potassium persulfate, inorganic peroxides such as sodium persulfate. These may be used alone or in combination of two or more.

  Examples of the photopolymerization initiator include acetophenone, 3-methylacetophenone, benzyldimethyl ketal, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, 2-methyl-1- [4 -(Methylthio) phenyl] -2-morpholinopropan-1-one, acetophenones such as 2-hydroxy-2-methyl-1-phenylpropan-1-one; benzophenone, 4-chlorobenzophenone, 4,4′-diamino Benzophenones including benzophenone; benzoin ethers such as benzoin propyl ether and benzoin ethyl ether; thioxanthones such as 4-isopropylthioxanthone; xanthone, fluorenone, camphorquinone, benzaldehyde, anthraquinone and the like. These may be used alone or in combination of two or more.

  Commercially available photopolymerization initiators may be used. For example, 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, made by DKSH Japan Ltd.), Kayacure (registered trademark) BMS, DMBI (above, manufactured by Nippon Kayaku Co., Ltd.) Is mentioned.

  Moreover, in the synthesis | combination of a (meth) acrylic acid ester copolymer (A), in order to adjust molecular weight, a chain transfer agent can also be used. For example, methyl mercaptan, t-butyl mercaptan, decyl mercaptan, benzyl mercaptan, lauryl mercaptan, stearyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, mercaptoacetic acid, mercaptopropionic acid and its ester, 2-ethylhexylthioglycol, thioglycol Mercaptans such as octyl acid; alcohols such as methanol, ethanol, propanol, n-butanol, isopropanol, t-butanol, hexanol, benzyl alcohol, and allyl alcohol; halogenated hydrocarbons such as chloroethane, fluoroethane, and 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.

  Moreover, the amount of each raw material monomer used in the production of the (meth) acrylic acid ester copolymer (A) is such that the component (a1) is 9.9 mass% or more and 99.9 mass% or less, The component is 0.1% by mass to 15% by mass, the (a3) component is 0% by mass to 20% by mass, and the (a4) component is 0% by mass to 90% by mass. The preferable range of these usage-amounts is as having mentioned above.

  As described above, the optical film pressure-sensitive adhesive of the present invention is an optical film pressure-sensitive adhesive containing a (meth) acrylic acid ester copolymer (A), and the (meth) acrylic acid ester copolymer ( A) is a structural unit derived from (a1) an alkyl (meth) acrylate monomer; 9.9% by mass to 99.9% by mass; and (a2) a structural unit derived from a macromonomer having a polymerizable functional group. 1% by mass or more and 15% by mass or less; and (a3) a structural unit derived from a functional group-containing monomer that is a (meth) acrylic acid derivative monomer not having a plurality of radical polymerizable functional groups; (A4) a structural unit derived from a (meth) acrylic acid ester monomer other than (a1), (a2) and (a3), from 0% by mass to 90% by mass; 2) The total amount of structural units derived from (a3) and (a4) is 100% by mass, and the glass transition temperature of the (meth) acrylic acid ester copolymer is −70 ° C. or higher and −57 ° C. or lower. And the weight average molecular weight exceeds 1 million and is 2.5 million or less.

  An optical member (adhesive optical film) having an adhesive layer obtained from the optical film adhesive having such a configuration can have the desired effect of the present invention.

[Crosslinking agent (B)]
The pressure-sensitive adhesive of the present invention preferably further contains a cross-linking agent (B) in order to efficiently achieve the desired effect of the present invention.

  The kind of the crosslinking agent (B) that can be used in the pressure-sensitive adhesive of the present invention is not particularly limited, and is an isocyanate compound, a carbodiimide compound, an oxazoline compound, an epoxy compound, a polyfunctional acrylate monomer, a peroxide, or a titanium coupling agent. And at least one selected from the group consisting of a zirconium compound, a metal aluminum chelate, a hydrazide compound, and a thermal acid generator. In particular, the cross-linking agent (B) is an isocyanate compound, a carbodiimide compound, an oxazoline compound, an epoxy compound (except when it corresponds to the components (a1), (a2), (a3) and (a4)), polyfunctional acrylic It is preferable that it is at least one selected from the group consisting of acid ester monomers (excluding cases corresponding to the components (a1), (a2), (a3) and (a4)) and peroxides, and adhesiveness From the viewpoint of ensuring durability, at least one of an isocyanate compound and a peroxide is preferable.

  The crosslinking agent (B) of the present invention includes those that form a crosslinked structure by themselves (curing agent type), and those that do not form a crosslinked structure by themselves but accelerate the crosslinking reaction (curing catalyst). In particular, the latter are peroxides, thermal acid generators and the like.

  The addition amount of the cross-linking agent (B) is preferably 0.001 part by mass or more and 20 parts by mass or less, more preferably 0.001 part by mass with respect to 100 parts by mass of the (meth) acrylic acid ester copolymer (A). It is 01 mass part or more and 5 mass parts or less, and from a viewpoint of adhesiveness and durability, More preferably, it is 0.01 mass part or more and 1 mass part or less. Furthermore, the upper limit of the addition amount of the crosslinking agent (B) is particularly preferably less than 1% by mass from the viewpoints of adhesiveness and bending resistance under high temperature and high humidity.

  That is, the preferable form of this invention is an adhesive for optical films which further contains a crosslinking agent (B). In another preferred embodiment of the present invention, the crosslinking agent (B) is contained in an amount of 0.001 to 20 parts by mass with respect to 100 parts by mass of the (meth) acrylic acid ester copolymer (A). It is an adhesive for optical films.

(Isocyanate compound)
The isocyanate compound suitably used as the crosslinking agent (B) is not particularly limited, and examples thereof include triallyl isocyanate, dimer acid diisocyanate, 2,4-tolylene diisocyanate (2,4-TDI), and 2,6-tril. Range isocyanate (2,6-TDI), 4,4′-diphenylmethane diisocyanate (4,4′-MDI), 2,4′-diphenylmethane diisocyanate (2,4′-MDI), 1,4-phenylene diisocyanate, xylylene Aromatic diisocyanates such as diisocyanate (XDI), tetramethylxylidene diisocyanate (TMXDI), tolidine diisocyanate (TODI), 1,5-naphthalene diisocyanate (NDI); hexamethylene diisocyanate (HDI), trimethylhexyl Aliphatic diisocyanates such as samethylene diisocyanate (TMHDI), lysine diisocyanate, norbornane diisocyanate methyl (NBDI); transcyclohexane-1,4-diisocyanate, isophorone diisocyanate (IPDI), H6-XDI (hydrogenated XDI), H12 -Alicyclic diisocyanates such as MDI (hydrogenated MDI); carbodiimide-modified diisocyanates of the above-mentioned diisocyanates; or these isocyanurate-modified diisocyanates. These can be used alone or in combination. Moreover, you may use together with the peroxide mentioned later. 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, an isocyanate compound may be synthesize | combined 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 Nippon Polyurethane Industry Co., Ltd.) ), Takenate (registered trademark) D-102, Takenate (registered trademark) D-110N, Takenate (registered trademark) D-200, Takenate (registered trademark) D-202 (manufactured by Mitsui Chemicals, Inc.), Duranate (registered) Trademark) 24A-100, Duranate (registered trademark) TPA-100, Duranate (registered trademark) TKA-100, Duranate (registered trademark) P301-75E, Duranate (registered trademark) E402-90T, Duranate (registered trademark) E405-80T , Duranate (registered trademark) TSE-100, Du Nate (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, 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 is preferable, and Coronate (registered trademark) L, Coronate (registered trademark) HX, and Duranate (registered trademark) 24A-100 are more preferable.

(Carbodiimide compound)
The carbodiimide compound suitably used as the crosslinking agent (B) is not particularly limited, and examples thereof include those described in paragraphs “0039” to “0046” of JP2012-246444 or those appropriately modified. It is done.

(Oxazoline compound)
The oxazoline compound suitably used as the crosslinking agent (B) is not particularly limited, and examples thereof include those described in paragraphs “0031” to “0037” of JP-A-2015-087539 or those appropriately modified. Can be mentioned.

(Epoxy compound)
Arbitrary appropriate epoxy type crosslinking agents can be employ | adopted as an epoxy type crosslinking agent (epoxy compound). Examples of commercially available products include “Tetrad C” and “Tetrad X” manufactured by Mitsubishi Gas Chemical Co., Inc., “Adeka Resin EPU Series” and “Adeka Resin EPR Series” manufactured by ADEKA Corporation, and “Celoxide” manufactured by Daicel Corporation. Etc. In particular, liquid epoxy resins such as these are preferred in that the pressure-sensitive adhesive mixing operation when producing the pressure-sensitive adhesive layer is facilitated.

(Polyfunctional acrylate monomer)
Examples of the polyfunctional acrylate monomer include hydrocarbon-based or hydrocarbon ether-based polyfunctional monomers. The hydrocarbon-based or hydrocarbon ether-based polyfunctional monomer is a compound in which a hydroxyl group of a polyhydric alcohol having a main skeleton of a hydrocarbon group having 10 to 100 carbon atoms or a hydrocarbon ether group is (meth) acrylated. Yes, from the viewpoint of adhesiveness due to crosslinking. Examples of the hydrocarbon group of the polyhydric alcohol include a linear or branched aliphatic hydrocarbon group, an aromatic hydrocarbon group, an alicyclic hydrocarbon group, and a hydrocarbon group obtained by combining these hydrocarbon groups. Examples of the hydrocarbon ether group include etherification of the hydrocarbon group. In addition, examples of the polyhydric alcohol having a hydrocarbon ether group as a main skeleton include compounds obtained by adding an alkylene oxide having 2 to 4 carbon atoms to the polyhydric alcohol (addition number 1 to 30 or less), and the like. And polyalkylene glycols (addition number 1 to 30) obtained from 4 or less alkylene oxides.

  Specific examples of the hydrocarbon-based bifunctional monomer include, for example, 1,3-butylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) ) Diacrylates of alkylene glycols such as acrylates and neopentyl glycol di (meth) acrylates; Alicyclic carbonizations such as cyclohexanedimethanol di (meth) acrylates and tricyclodecane dimethanol di (meth) acrylates Di (meth) acrylate of a diol compound having a hydrogen group; di (meth) acrylate of a diol compound having an aromatic hydrocarbon group such as bisphenol A di (meth) acrylate.

  Specific examples of the hydrocarbon ether-based bifunctional monomer include, for example, alkoxylated hexanediol di (meth) acrylate, alkoxylated cyclohexanedimethanol di (meth) acrylate, and alkoxylated di (meth) acrylate. , Dialkyl compounds of alkylene glycol and diol compounds obtained by adding alkylene oxide to the above-mentioned hydrocarbon-based bifunctional monomers such as alkoxylated neopentyl glycol di (meth) acrylate and alkoxylated bisphenol A di (meth) acrylate. And (meth) acrylate. Specific examples of the hydrocarbon ether-based bifunctional monomer include diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, Examples thereof include di (meth) acrylates of polyalkylene glycols such as tripropylene glycol di (meth) acrylate and dipropylene glycol di (meth) acrylate, and dioxane glycol di (meth) acrylate.

  In addition, as a hydrocarbon-based or hydrocarbon ether-based trifunctional monomer or tetrafunctional monomer, for example, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, glyceryl tri (meth) acrylate, Tri (meth) acrylate or tetra (meth) acrylate of tri- or tetraol compounds such as pentaerythritol tetra (meth) acrylate and trimethylolpropane tetra (meth) acrylate, and compounds obtained by adding alkylene oxide to the above tri- or tetraol compounds And tri (meth) acrylate or tetra (meth) acrylate.

  Further, as the non-urethane polyfunctional monomer (b) other than the hydrocarbon type or hydrocarbon ether type, polyester poly (meth) acrylate having two or more (meth) acrylate groups at the terminal, epoxy (meth) acrylate Etc.

(Peroxide)
As the peroxide suitably used as the crosslinking agent (B), any peroxide can be used as long as it can generate radicals by heating to achieve crosslinking of the pressure-sensitive adhesive, but in consideration of workability and stability, 1 It is preferable to use a peroxide having a minute half-life temperature of preferably 80 ° C. to 160 ° C., more preferably 90 ° C. to 140 ° C. The half-life of the peroxide is an index representing the decomposition rate of the peroxide, and is the time for which the amount of peroxide decomposition is halved. The decomposition temperature for obtaining the half-life at an arbitrary time In addition, the half-life at an arbitrary temperature is described in the manufacturer catalog and the like, for example, in the organic peroxide catalog 9th edition (May 2003) published by Nippon Oil & Fats Co., Ltd. ing.

  Examples of such peroxides include bis (2-ethylhexyl) peroxydicarbonate (1 minute half-life temperature 90.6 ° C), bis (4-t-butylcyclohexyl) peroxydicarbonate (92.1 ° C). ), Bis-sec-butyl peroxydicarbonate (92.4 ° C.), t-butyl peroxyneodecanoate (103.5 ° C.), t-hexyl peroxypivalate, (109.1 ° C.) ), T-butyl peroxypivalate (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.), bis (4-methylbenzoyl) peroxide (128.2 ° C.), dibenzoy Peroxide (130.0 ° C.) and t-butyl peroxybutyrate (136.1 ° C.), and the like, and bis (4-t-butylcyclohexyl) peroxydicarbonate and dilauroyl parper having excellent crosslinking reaction efficiency. Oxides and dibenzoyl peroxide are preferably used. In particular, bis (4-t-butylcyclohexyl) peroxydicarbonate is preferred from the viewpoint of the decomposition temperature. One or more of these can be used. Moreover, you may use together with the above-mentioned isocyanate compound.

(Titanium coupling agent)
The titanium coupling agent suitably used as the crosslinking agent (B) is not particularly limited, and examples thereof include those described in paragraph “0072” of JP-A-2014-085616 or those appropriately modified.

(Zirconium compound)
The zirconium compound suitably used as the crosslinking agent (B) is not particularly limited, and examples thereof include those described in paragraph “0073” of JP-A-2014-085616 or those appropriately modified.

(Metal aluminum chelate)
The metal aluminum chelate suitably used as the crosslinking agent (B) is not particularly limited, and examples thereof include those described in paragraph “0058” of JP2012-229373A and paragraph “of JP2008-251089”. And those modified as appropriate.

(Hydrazide compound)
The hydrazide compound is not particularly limited, and a hydrazine-based crosslinking agent having at least two hydrazino groups and semicarbazide groups is preferable. Examples of the compound having at least two hydrazino groups include polyhydrazides of aliphatic polybasic acids such as oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide; Polyhydrazide of polybasic acid; polyhydrazide of polyacrylic acid; polyhydrazide of aromatic hydrocarbon; hydrazine-pyridine derivative; polyhydrazide of unsaturated polybasic acid such as maleic acid dihydrazide; polyhydrazide carbonate and the like. In addition, as the compound having at least two semicarbazide groups, for example, a semicarbazide compound such as an aliphatic, alicyclic, aromatic polysemicarbazide, or the like can be used.

(Thermal acid generator)
Examples of the thermal acid generator include hexafluoroantimonate-based sulfonium salts exemplified as energy acid generators, and commercially available products include SI-60, SI-60L, SI-80, SI-80L, SI- 100, SI-100L (above, manufactured by Sanshin Chemical Co., Ltd.), CI-2624 (manufactured by Nippon Soda Co., Ltd.). A thermal acid generator may be used independently and may be used in combination of 2 or more types.

  That is, in a preferred embodiment of the present invention, the crosslinking agent (B) is at least one of an isocyanate compound, a carbodiimide compound, an oxazoline compound, an epoxy compound, a polyfunctional acrylate monomer, a peroxide, a hydrazide compound, and a thermal acid generator. It is a kind of pressure-sensitive adhesive for optical films.

[Silane coupling agent (C)]
The pressure-sensitive adhesive of the present invention can further contain a silane coupling agent (C) from the viewpoint of improving adhesiveness. Either (C) component or (B) component may be used, or both may be used in combination.

  A silane coupling agent refers to one having no siloxane bond and having two or more different reactive groups in the molecule.

  The silane coupling agent (C) used in the pressure-sensitive adhesive of the present invention is not particularly limited. For example, 3-glycidoxypropyltriethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane, n-propyl Trimethoxysilane, ethyltrimethoxysilane, diethyldiethoxysilane, n-butyltrimethoxysilane, n-hexyltriethoxysilane, n-octyltrimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, cyclohexylmethyldimethoxysilane, vinyl Trichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glyci Doxypropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxy Propylmethyldiethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-acryloxypropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane, N-β- (aminoethyl)- γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltri Metoki Silane, γ-chloropropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, bis- (3- [triethoxysilyl] propyl) tetrasulfide, γ-isocyanatopropyltriethoxysilane, etc. Can be mentioned. 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 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.

  The said silane coupling agent may be used independently and may be used in combination of 2 or more type.

  In the present invention, the amount added in the case of containing the silane coupling agent (C) is more preferably 0.0001 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the copolymer (A). It is more preferably 0.001 part by mass or more and 5 parts by mass or less, and particularly preferably 0.01 part by mass or more and 3 parts by mass or less. If it is such a range, durability can be improved. That is, the preferable form of this invention is 0.001 mass part or more and 5 mass parts or less of silane coupling agents (C) with respect to 100 mass parts of said (meth) acrylic acid ester copolymers (A). It is an adhesive for optical films.

[Use]
The above-mentioned pressure-sensitive adhesive of the present invention is suitable for various applications. For example, it is preferably used for an optical film. Such an optical film is not particularly limited, and examples thereof include those used for forming an image display device such as a liquid crystal display device. For example, the optical film includes at least a polarizing plate or a retardation plate, and further includes a conductive layer and a protective layer. Including a cover film, a transparent conductive film, a window film, an optical compensation film such as a viewing angle widening film for improving the viewing angle of a liquid crystal display, a brightness enhancement film for increasing the contrast of the display, and May be one in which these are laminated.

  In the present invention, there are provided a form of an adhesive layer formed by the above-described adhesive, and an optical member formed by forming the adhesive layer on an optical film or the like. Further, the optical member is an adhesive optical film (for example, an adhesive polarizing plate), or the optical member is a liquid crystal display device, an organic EL display device, a plasma display (PDP), a curved display or a flexible display. The form etc. which are applied to the image display apparatus etc. of this can be provided.

<Adhesive layer>
In this invention, the adhesive layer formed from the adhesive of this invention is also provided.

  In this invention, an adhesive layer can be formed by apply | coating the adhesive of this invention to a base material etc., and drying and removing a solvent etc. In applying the adhesive, one or more solvents may be added as appropriate.

  In addition, the separator mentioned later can be used as a base material of an adhesive layer.

  The application method is not particularly limited, and various 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.

  As a method for drying the solvent present in the pressure-sensitive adhesive, an appropriate method can be adopted depending on the purpose. Preferably, a method of heating and drying the coating film is used. The heat drying temperature is preferably 40 ° C. or higher and 200 ° C. or lower, more preferably 50 ° C. or higher and 180 ° C. or lower, and particularly preferably 70 ° C. or higher and 170 ° C. or lower. By setting the heating temperature in the above range, an adhesive layer having excellent adhesive properties can be obtained.

  Moreover, although drying time can be set suitably, Preferably it is 5 to 30 minutes, More preferably, it is 5 to 20 minutes, Most preferably, it is 10 to 15 minutes. Heat drying can be performed twice or more under different conditions.

  The thickness (dry film thickness) of the pressure-sensitive adhesive layer of the present invention is not particularly limited and can be appropriately set depending on the intended use. For example, when used for an optical film, from the viewpoint of adhesion, durability, and bending durability, it is preferably 1 μm or more and 200 μm or less, more preferably 5 μm or more and 150 μm or less, and 10 μm or more and 120 μm or less. It is particularly preferred.

According to a preferred embodiment of the present invention, the storage elastic modulus (G ′ (− 20)) at −20 ° C. is 1 × 10 ⁵ Pa or less and the storage elastic modulus at 85 ° C. (G ′ (85 )) Is 1 × 10 ⁴ Pa or more.

When the storage elastic modulus (G ′ (− 20)) at −20 ° C. of the pressure-sensitive adhesive layer is 1 × 10 ⁵ Pa or less, the pressure-sensitive adhesive layer has characteristics as a pressure-sensitive adhesive that can be followed when bent. Moreover, it is that it has sufficient heat resistance that the storage elastic modulus (G '(85)) in 85 degreeC is 1 * 10 < ⁴ > Pa or more.

The storage elastic modulus (G ′ (− 20)) at −20 ° C. of the pressure-sensitive adhesive layer is preferably 5 × 10 ⁴ Pa or less, more preferably 4 × 10 ⁴ Pa or less, and 3 × 10 ^4. Even more preferably, it is Pa or less.
Further, the lower limit of the storage elastic modulus (G ′ (− 20)) at −20 ° C. is preferably 1 × 10 ⁴ Pa or more, more preferably 2 × 10 ⁴ Pa or more. .

On the other hand, the storage elastic modulus (G ′ (85)) at 85 ° C. is preferably 1.0 × 10 ⁴ Pa or more, and from the viewpoint of durability, it is 1.2 × 10 ⁴ Pa or more. More preferred. Further, the upper limit of the storage elastic modulus (G ′ (85)) at 85 ° C. is more preferably 2 × 10 ⁵ Pa or less, and further preferably 1 × 10 ⁵ Pa or less.

  Further, the ratio between G ′ (− 20) and G ′ (85), that is, the value of G ′ (− 20) / G ′ (85) is not limited, but adhesion, durability and bending durability are not limited. In view of the above, it is preferably 1.0 or more and 5.0 or less, and more preferably 1.1 or more and 4.0 or less. Even more preferably, from the viewpoint of durability at high temperatures, G ′ (− 20) / G ′ (85) is 1.1 or more and less than 3.0. In addition, a storage elastic modulus shall be measured by the method as described in an Example.

  Moreover, when the adhesive layer concerning this invention is exposed, an adhesive layer can be protected with the sheet | seat (separator) etc. which were peel-processed until it was used practically.

  As a constituent material of the separator, for example, a plastic film such as polyethylene, polypropylene, polyethylene terephthalate, and a polyester film, a porous material such as paper, cloth, and nonwoven fabric, a net, a foam sheet, a metal foil, and a laminate thereof. Although an appropriate thin leaf body etc. can be mentioned, a plastic film is used suitably from the point which is excellent in surface smoothness.

  The thickness of the substrate (for example, a separator) is usually 5 μm or more and 200 μm or less, preferably 5 μm or more and 100 μm or less.

  For separators, silicone, fluorine, long-chain alkyl or fatty acid amide release agents, 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 performed. In particular, the release property from the pressure-sensitive adhesive layer can be further improved by appropriately performing a release treatment such as a silicone treatment, a long-chain alkyl treatment, or a fluorine treatment on the surface of the separator.

  Moreover, in this invention, the form of the adhesive layer which has a corona treatment layer or a plasma treatment layer at least on one side is also provided.

<Optical member>
The present invention also provides an optical member in which the pressure-sensitive adhesive layer of the present invention is formed on at least one side of the optical film. In other words, the “optical member” can be said to be an “adhesive optical film”.

  The optical member of the present invention may have a configuration in which the pressure-sensitive adhesive layer is formed by directly applying the pressure-sensitive adhesive of the present invention on one or both sides of the optical film, or indirectly through an easily adhesive layer. Alternatively, a configuration in which an adhesive layer is formed may be used. Therefore, in the preferable form of this invention, the form of the optical member which has an easily bonding layer between an optical film and the said adhesive layer is also provided.

  As the easy-adhesion layer, a member that contacts the pressure-sensitive adhesive layer, such as corona treatment or plasma treatment, or a member that contacts a pressure-sensitive adhesive layer, such as a primer layer, may be used. It may be provided on the surface. That is, the preferable form of this invention is an optical member whose said easily bonding layer is a corona treatment layer, a plasma treatment layer, or a primer layer from a viewpoint of adhere | attaching an optical film and an adhesive firmly.

[Primer layer]
In the present invention, the material for forming the primer layer is good for both an adhesive layer and an optical film (for example, a transparent protective film for a polarizing plate) (or a member in contact with the adhesive layer), or a normal optical film. What forms the film | membrane which shows adhesiveness and is excellent in cohesion force is preferable. For example, various polymers, metal oxide sols, silica sols and the like are used, and polymers are particularly preferably used. The primer layer may have an antistatic function as described above.

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

  As this oxazoline group-containing polymer, a general commercial product is used, and 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.

  In the present invention, a primer layer can be formed by applying and drying a primer for forming a primer layer on an optical film using a coating method such as a coating method, a dipping method, or a spray method.

  The primer layer has a thickness (dry film thickness) of about 10 nm to 5000 nm, preferably 50 nm to 500 nm. If it is such a range, it has the property as a bulk, and it can also maintain an optical characteristic, showing sufficient intensity | strength and sufficient adhesiveness.

  As described above, according to a preferred embodiment of the present invention, the optical film has a conductive layer. At this time, the material for forming the conductive layer is not particularly limited, but the material for forming the conductive layer may be indium tin oxide (ITO), silver nanowire, indium zinc oxide, indium oxide- Selected from the group consisting of zinc oxide composite oxide, polythiophene, carbon nanotube, aluminum zinc oxide, gallium zinc oxide, fluorine zinc oxide, fluorine indium oxide, antimony tin oxide, fluorine tin oxide and phosphorus tin oxide Preferably, at least one kind is used.

  Moreover, according to the preferable form of this invention, the said optical film has a protective layer. By forming the protective layer, the metal corrosion of the conductive layer can be suppressed.

  According to a preferred embodiment of the present invention, the optical film includes a polarizing plate. Therefore, below, the case where a polarizing plate is contained in the optical film concerning this invention is demonstrated as an example.

Below, the case where the optical film concerning this invention is a polarizing plate is demonstrated as an example.

[Polarizer]
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. In the present invention, even if a film such as a retardation film is bonded to a polarizer, the retardation film is considered as a part of the polarizing plate. The retardation film may be used as a protective film for protecting the polarizer.

  There is no restriction | limiting in particular as a polarizer, A conventionally well-known thing can be used. For example, a dichroic material such as iodine or a dichroic dye is adsorbed on a hydrophilic polymer film such as a polyvinyl alcohol film, a partially formalized polyvinyl alcohol film, or an ethylene / vinyl acetate copolymer partially saponified film. Examples include stretched films, polyene-oriented films such as polyvinyl alcohol dehydrated products and polyvinyl chloride dehydrochlorinated products.

  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 an aqueous solution of iodine, for example, it is preferably immersed in an aqueous solution containing 0.1% by mass or more and 1.0% by mass or less of iodine and / or potassium iodide. Moreover, you may immerse and extend | stretch in aqueous solutions, such as a boric acid and potassium iodide, 50 degreeC or more and 70 degrees C or less as needed. Moreover, you may immerse in 25 degreeC or more and 35 degrees C or less water for washing | cleaning and prevention of uneven dyeing.

  In addition, extending | stretching may be performed after dyeing with iodine, may be extended while dyeing, or may be dyed with iodine after being extended.

  After dyeing and stretching, it may be washed with water or an aqueous solution containing iodine and / or potassium iodide, and dried at 35 ° C. or higher and 55 ° C. or lower for 1 minute or more and 10 minutes or less. There are a wide variety of such polarizers.

  The thickness of the polarizer is not particularly limited, but is more preferably about 1 μm or more and 50 μm or less.

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

  A transparent protective film may be bonded to one side of the polarizer with an adhesive. In that case, on the other side, a transparent protective film or a protective layer (meth) acrylic, urethane-based, acrylic A thermosetting resin such as urethane, epoxy, or silicone, 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. Moreover, in this invention, it is preferable that it is 100 micrometers or less from a viewpoint of thickness reduction and a bending. Therefore, according to the preferable form of this invention, the said optical film is a polarizing plate, and the thickness of the said polarizing plate is 100 micrometers or less. Furthermore, it is more preferably 90 μm or less, and particularly preferably 80 μm or less. Such a thin polarizing plate is preferable from the viewpoint of more remarkably expressing the effect of the pressure-sensitive adhesive 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 10,000 nm 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 to obtain a uniform in-plane thickness and to obtain a sufficient adhesive force, so that the polyvinyl alcohol-based adhesive has a thickness of 10 nm to 200 nm, and the ultraviolet curable adhesive has a thickness of 0.2 μm to 10 μm. It is preferable that

<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, from the viewpoint of more remarkably expressing the effect of the pressure-sensitive adhesive of the present invention, it is preferably applied particularly to a thin image display device, a curved display, a flexible display, and the like. That is, a preferred embodiment of the present invention is an image display device that is a curved display or a flexible display.

  As described above, the present invention relates to a pressure-sensitive adhesive for optical films, a pressure-sensitive adhesive layer for optical films, a pressure-sensitive adhesive optical film, and an image display device, and an optical material in which the obtained laminate is bonded under each durability test condition. It is possible to provide a pressure-sensitive adhesive that hardly peels off or floats even when held for a long time or subjected to a bending test in a state where the film is deformed. The pressure-sensitive adhesive of the present invention is suitably used for laminating thin adherends including optical films or sheets, and various films or sheets used for liquid crystal display elements such as flexible displays and electroluminescent elements. And can be used commercially in these technical fields.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In addition, both parts and% in each example are based on mass. Hereinafter, all the room temperature standing conditions not specifically defined are 23 ° C./55% RH.

<Measurement of weight average molecular weight of (meth) acrylic acid ester copolymer (A)>
The weight average molecular weight of the (meth) acrylic acid ester copolymer (A) was measured by GPC (gel permeation chromatography).

・ Analyzer: HLC-8120GPC, manufactured by Tosoh Corporation
-Column: Tosoh Corporation G7000HXL + GMHXL + GMHXL
・ 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.

(Creation of thin polarizing plate)
The creation of a thin polarizing plate will be described with reference to FIG.

  A polyvinyl alcohol film having a thickness of 20 μm was stretched up to 3 times while being dyed for 1 minute in an iodine solution of 0.3% concentration at 30 ° C. between rolls having different speed ratios. Thereafter, the film was stretched until it was 6 times as long as it was immersed in an aqueous solution containing 60% at 4% concentration of boric acid and 10% concentration of potassium iodide for 0.5 minutes. Next, after washing by immersing in an aqueous solution containing potassium iodide at 30 ° C. and 1.5% concentration for 10 seconds, drying was performed at 50 ° C. for 4 minutes to obtain a polarizer 4 having a thickness of 7 μm.

  A polycarbonate film 2 having a thickness of 20 μm is formed on one surface of the polarizer 4, and a retardation film 6 having a film thickness of 50 μm is formed on a surface of the polarizer 4 on the opposite side of the polarizer 4. ”) Was bonded to each other with polyvinyl alcohol adhesives 3 and 5 to form a thin polarizing plate 1 having a total thickness of 77 μm.

<Creation of conductive layer>
As shown in FIG. 1, the following conductive layer-forming coating material was applied to the surface of the retardation film 6 of the thin polarizing plate by a die coating method so that the solid content coating amount was 1 g / m ^2, and at 80 ° C. After drying, a conductive layer 7 was laminated on the retardation film 6.

(Conductive layer forming paint)
70 parts by mass of ultrapure water (Wako Pure Chemical Industries, Ltd., Ultrapure Water Ultrapure Water) per 30 parts by mass of silver nanowire dispersion solution (manufactured by Camrios, USA, CleraOhm Ink-A AQ) 0.12 part of Clear Ohm SFT-D, manufactured by the company, was added to prepare a coating material for forming a conductive layer.

<Creation of protective layer>
On the conductive layer 7 laminated on the retardation film 6 as described above, the following protective layer-forming coating material is applied by a die coating method so that the thickness of the protective layer (thickness after curing) is 210 nm. The protective layer 8 was formed by drying and irradiating with UV (manufactured by Heraeus, LH10-70UV lamp) (accumulating light amount: 200 mJ / cm ² ).

(Protective layer forming paint)
A protective layer-forming coating material was prepared by adding 95 parts by mass of ethyl acetate per 5 parts by mass of an acrylic resin-based paint (manufactured by China Paint Co., Ltd., Forse Seed No. 420C resin concentration: 50% by mass).

(Production Example 1)
<Preparation of (meth) acrylic acid ester copolymer (A1)>
In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser, 90 parts of 2-ethylhexyl acrylate, 2 parts of methyl methacrylate macromonomer AA-6 (manufactured by Toagosei Co., Ltd.), 4-hydroxybutyl After 8 parts of acrylate and 0.1 part of 2,2′-azobisisobutyronitrile (AIBN) as a polymerization initiator were charged with 100 parts of ethyl acetate, nitrogen gas was introduced while gently stirring, and the atmosphere was replaced with nitrogen. A polymerization reaction was carried out for 5 hours while maintaining the liquid temperature in the flask at around 55 ° C. to prepare a solution of a (meth) acrylic acid ester copolymer (A1) having an Mw (weight average molecular weight) of 1.7 million.

(Production Examples 2-19, 21-25, 27-28)
In Production Example 1, in the same manner as in Production Example 1, except that the type or proportion of the monomer forming the (meth) acrylic acid ester copolymer (A) and the polymerization initiator were changed as shown in Table 1. Solutions of (meth) acrylic acid ester copolymers (A2) to (A19), (A21) to (A25), and (A27) to (A28) were prepared. Tg (glass transition temperature) and Mw (weight average molecular weight) of (meth) acrylic acid ester copolymers (A2) to (A19), (A21) to (A25), and (A27) to (A28) are shown in Table 1. As shown in

(Production Example 20)
Acrylic syrup (A20) was prepared as shown below.

  The reaction was carried out in a reaction box in which four black lights (FL20SBL manufactured by Sankyo Electric Co., Ltd.) flasks were installed in four directions in an environment where external ultraviolet rays were cut.

  In a 2-liter four-necked flask equipped with a stirrer, thermometer, nitrogen gas inlet tube and cooling tube in the box, 90 parts of 2-ethylhexyl acrylate, methyl methacrylate macromonomer AA-6 (manufactured by Toagosei Co., Ltd.) 2 parts and 8 parts of 4-hydroxybutyl acrylate were added and heated to 30 ° C. while the air in the flask was replaced with nitrogen.

  Next, 0.005 part of 2,2-dimethoxy-1,2-diphenylethane-1-one (Irgacure (registered trademark) 651, manufactured by BASF Japan Ltd.) is added as a polymerization initiator under stirring and uniformly. Mixed.

Here, black light (integrated light amount 200 mJ / cm ² ) was irradiated to start polymerization. Although the temperature of the reaction system rose after the reaction started, the reaction was forcibly stopped by introducing air with an air pump into the flask when the reaction temperature rose from the start to 10 ° C. A syrup (A20) was obtained. The Tg (glass transition temperature) and Mw (weight average molecular weight) of the (meth) acrylic acid ester copolymer in the acrylic syrup (A20) are as shown in Table 1.

(Production Example 26)
Acrylic syrup (A26) was prepared as shown below.

  In a 2 liter four-necked flask equipped with a stirrer, thermometer, nitrogen gas introduction tube and cooling tube, 90 parts of 2-ethylhexyl acrylate, 2 parts of methyl methacrylate macromonomer AA-6 (manufactured by Toagosei Co., Ltd.), 4 parts -8 parts of hydroxybutyl acrylate and 0.1 part of n-dodecyl mercaptan as a chain transfer agent were added, and the flask was heated to 50 ° C while the air in the flask was replaced with nitrogen. Next, 0.0025 part of 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile) (V-70; manufactured by Wako Pure Chemical Industries, Ltd.) was added as a polymerization initiator under stirring. Mix evenly.

  After the polymerization initiator was charged, the temperature of the reaction system rose, but when the polymerization reaction was continued without cooling, the temperature of the reaction system reached 120 ° C. and then gradually began to fall. When the temperature of the reaction system decreased to 115 ° C., 27 parts of 2-ethylhexyl acrylate, 0.6 parts of methyl methacrylate macromonomer AA-6 (manufactured by Toagosei Co., Ltd.), 2.4 parts of 4-hydroxybutyl acrylate and n- 0.08 part of dodecyl mercaptan was added and forced cooling was performed to cool to 50 ° C. Further, 0.005 part of V-70 was added as a polymerization initiator under stirring and mixed uniformly.

  After the polymerization initiator was charged, the temperature of the reaction system rose, but when the polymerization reaction was continued without cooling, the temperature of the reaction system reached 125 ° C. and then gradually began to fall. When the temperature of the reaction system decreased to 120 ° C., 20.7 parts of 2-ethylhexyl acrylate, 0.46 parts of methyl methacrylate macromonomer AA-6 (manufactured by Toagosei Co., Ltd.), 1.84 parts of 4-hydroxybutyl acrylate were added. Then, forced cooling was performed to obtain acrylic syrup (A26). The Tg (glass transition temperature) and Mw (weight average molecular weight) of the (meth) acrylic acid ester copolymer in the acrylic syrup (A26) are as shown in Table 1.

  In addition, the glass transition temperature of the (meth) acrylic acid ester copolymer (A) is a theoretical value calculated from the monomer unit constituting each polymer and its ratio by the FOX equation.

Formula of FOX: 1 / Tg = w1 / Tg1 + w2 / Tg2 + ... + wn / Tgn
(Tg: glass transition temperature (K) of polymer, Tg1, Tg2,... Tgn: glass transition temperature (K) of homopolymer of each monomer, w1, w2,... Wn: weight fraction of each monomer. )
The theoretical glass transition temperature obtained from the FOX equation is in good agreement with the measured glass transition temperature obtained by differential scanning calorimetry (DSC), dynamic viscoelasticity, and the like.

In Table 1, the abbreviations are as follows:
(A1) Component 2EHA: 2-ethylhexyl acrylate (homopolymer Tg-68 ° C.)
BA: Butyl acrylate (homopolymer Tg-45 ° C.)
(A2) Component AA-6: Macromonomer AA-6 (Homopolymer Tg 105 ° C.)
AS-6: Macromonomer AS-6 (Homopolymer Tg 100 ° C.)
AN-6S: Macromonomer AN-6S (Homopolymer Tg 99 ° C.)
AB-6: Macromonomer AB-6 (Homopolymer Tg-45 ° C.)
AW-6S: Macromonomer AW-6S (Homopolymer Tg 67 ° C.)
AK-5: Macromonomer AK-5 (Homopolymer Tg-123 ° C.)
(All components (a2) are manufactured by Toagosei Co., Ltd.)
(A3) Component HEAA: N- (2-hydroxyethyl) acrylamide (homopolymer Tg 98 ° C.)
4HBA: 4-hydroxybutyl acrylate (homopolymer Tg −40 ° C.)
GMA: Glycidyl methacrylate (homopolymer Tg 41 ° C.)
AAEM: acetoacetoxyethyl methacrylate (homopolymer Tg 9 ° C.)
(A4) Component MEA: Methoxyethyl acrylate (Homopolymer Tg-50 ° C)
EC-2: A: ethoxy-diethylene glycol acrylate (homopolymer Tg-70 ° C.).

<Example 1>
(Preparation of adhesive)
With respect to 100 parts of the solid content of the (meth) acrylic acid ester copolymer (A1) solution obtained in Production Example 1, the isocyanate crosslinking agent Takenate (registered trademark) D-110N (xylylene diisocyanate) as the crosslinking agent (B) A solution of acrylic pressure-sensitive adhesive (solid content 15%) containing 0.1 part of a 75% ethyl acetate solution of trimethylolpropane adduct of No. 3 in 1 molecule, 3 isocyanate groups, manufactured by Mitsui Chemicals, Inc. Was prepared.

(Formation of adhesive layer)
Next, the acrylic adhesive solution was subjected to silicone treatment (peeling treatment) on one side of a 50 μm-thick polyethylene terephthalate (PET) film (MRF50, manufactured by Mitsubishi Chemical Polyester Film Co., Ltd.) after drying. The pressure-sensitive adhesive layer was coated with a die coater so as to have a thickness of 100 μm, dried at 80 ° C. for 3 minutes, and then dried at 120 ° C. for 10 minutes to form an adhesive layer (100 μm).

(Preparation of polarizing plate with adhesive layer)
On the protective layer 8 side, corona treatment was performed with a corona discharge of 80 W · min / m ² to form an easy adhesion layer (not shown) on the protective layer.

  Next, the silicone-treated PET film on which the pressure-sensitive adhesive layer is formed is transferred so that the pressure-sensitive adhesive layer and the protective layer 8 are in contact with each other via an easy-adhesion layer, and a polarizing plate with an pressure-sensitive adhesive layer (optical member) ) Was produced.

<Examples 2-26, 28-29 and Comparative Examples 1-5>
As shown in Table 2, the type of (meth) acrylic acid ester copolymer (A) (polymer type), the type of cross-linking agent or the amount used thereof were changed, and depending on the example, the ratio shown in Table 2 A polarizing plate with a pressure-sensitive adhesive layer (optical member) was prepared in the same manner as in Example 1 except that a silane coupling agent was used and, depending on the example, a polymerization initiator was used in the ratio shown in Table 2. did.

<Example 27>
Trimethylolpropane triacrylate (light acrylate TMP-A; manufactured by Kyoeisha Chemical Co., Ltd.) having the blending amounts shown in Table 2 with respect to 100 g of the active ingredient in acrylic syrup obtained in Production Example 20, is referred to as “TMP-”. A "), biuret type hexamethylene diisocyanate (Duranate (registered trademark) 24A-100; manufactured by Asahi Kasei Chemicals Corporation, hereinafter referred to as" 24A-100 "), 2-hydroxy-2-methyl-1-phenyl-propane- 1-one (Irgacure (registered trademark) 1173; manufactured by BASF Japan Ltd., hereinafter referred to as “I-1173”) and silane coupling agent 3-glycidoxypropyltriethoxysilane (KBE-403; Shin-Etsu Chemical Co., Ltd.) Co., Ltd., hereinafter referred to as “KBE-403”) Process to obtain photopolymerizable pressure-sensitive adhesive composition (solution of acrylic adhesive).

  Here, 32.5 g of the (meth) acrylic acid ester copolymer (A20) is contained in 100 g of the active ingredient in the acrylic syrup, and 67.5 g of the remaining unreacted monomer is contained.

  This photopolymerizable pressure-sensitive adhesive composition was applied on the release surface of a 50 μm thick polyethylene terephthalate (PET) film that had been peeled on one side (that is, siliconized) so that the coating thickness was 100 μm. Then, a PET separator having a thickness of 50 μm that was peeled off was stuck on the coated surface, and the PET separator was placed above and below the pressure-sensitive adhesive composition and sealed in a sandwich shape, and then 5.0 mW with black light. Was irradiated for 10 minutes to obtain a colorless and transparent acrylic sheet (adhesive layer).

  Next, one of the PET separators is peeled off to expose the colorless and transparent acrylic sheet (adhesive layer), and the adhesive layer and the protective layer 8 are transferred so as to be in contact with each other via the easy-adhesion layer, and the adhesive layer An attached polarizing plate was produced.

<Comparative Example 6>
Trimethylolpropane triacrylate (light acrylate TMP-A; manufactured by Kyoeisha Chemical Co., Ltd.) having the blending amounts shown in Table 2 with respect to the active ingredient of 100 g of acrylic syrup obtained in Production Example 26, and “TMP-A” hereinafter. Biuret type hexamethylene diisocyanate (Duranate (registered trademark) 24A-100; manufactured by Asahi Kasei Chemicals Corporation, hereinafter referred to as “24A-100”), 2-hydroxy-2-methyl-1-phenyl-propan-1-one (Irgacure (registered trademark) 1173; manufactured by BASF Japan Ltd., hereinafter referred to as “I-1173”) and 3-glycidoxypropylmethyldiethoxysilane (KBE-403; Shin-Etsu Chemical Co., Ltd.) which is a silane coupling agent Manufactured, hereinafter referred to as “KBE-403”) It was obtained photopolymerizable pressure-sensitive adhesive composition (solution of acrylic adhesive) and foam processing. And the polarizing plate with an adhesive layer was produced like Example 27. As shown in FIG.

  The following evaluation was performed about the polarizing plate with an adhesive layer (optical member) obtained by the said Example and comparative example. The evaluation results are shown in Table 3.

<Durability>
A film having a silicon nitride (SiN _x ) film having a thickness of 50 nm on the outermost surface of a polyimide film having a thickness of 0.7 mm was used as an alternative to the flexible panel.

  The polarizing plate sample with an adhesive layer was made into a 5-inch size, the said polyethylene terephthalate (PET) film was peeled off, and it affixed on the polyimide film 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 polyimide film. Thereafter, the sample was sandwiched and fixed with a glass plate so that the inner diameter (diameter) could be maintained at 6 mm.

  (1) The sample subjected to such treatment was treated at 85 ° C. (10% RH or less) for 500 hours (heating test).

  (2) Moreover, it processed for 500 hours in 60 degreeC / 95% RH atmosphere (humidification test).

  (3) In addition, an environment of 85 ° C. and −40 ° C. was subjected to 300 cycles in one cycle for 1 hour (heat shock test, “HS 300 cycles” in Table 3).

  About each test, the external appearance of a polarizing plate and a polyimide film was visually evaluated on the following reference | standard.

◎: No change in appearance such as foaming, peeling, floating, no cracking, etc. ○: Slightly peeling off at the end, foaming or cracking, but no practical problem △: peeling off at the end, foaming, or There is a crack, but there is no practical problem unless it is a special use.

  In the tests (1), (2), and (3), samples are prepared and the tests are performed independently.

<Bending resistance (bending test 100,000 times)>
The same sample as used in the above durability test (autoclaved at 50 ° C. and 0.5 MPa for 15 minutes) was newly prepared and bent by a bending tester (manufactured by Yuasa System Equipment Co., Ltd.). Conditions were set so that the inner diameter (diameter) would be 6 mm, and bending and 180 ° opening were performed as one cycle and repeated 100,000 cycles. The test environments were (1) 23 ° C./55% RH atmosphere, (2) 85 ° C. (10% RH or less), (3) 60 ° C./95% RH atmosphere, and (4) -20. Performed at ° C. The appearance of the polarizing plate and the polyimide film after the test was visually evaluated according to the following criteria.

  In the tests of (1), (2), (3) and (4), samples are prepared and the tests are performed independently.

  A: No change in appearance such as foaming, peeling, floating, no cracks

  ○: Slightly peeled off at the end, foamed or cracked, but no problem in practical use

  Δ: Peeled, foamed or cracked at the end, but practically no problem unless special use

  X: Remarkably peeled off at the end, causing practical problems.

<Adhesive strength>
The same samples as those used in the durability test were newly prepared, each cut into a width of 25 mm and a length of 100 mm, and then autoclaved at 50 ° C. and 0.5 MPa for 15 minutes to be completely adhered. Then, after leaving still for 1 hour in 23 degreeC / 55% RH atmosphere, the adhesive force of this sample was measured.

  The adhesive strength was determined by using a tensile tester with a thermostatic bath (Orientec Co., Ltd. Tensilon Universal Material Testing Machine STA-1150) under the conditions of 23 ° C. and relative humidity 55% RH, peeling angle 180 °, peeling speed. This was determined by measuring the adhesive force (N / 25 mm) at the time of peeling according to the method of JIS Z0237 (2009) pressure sensitive adhesive tape and pressure sensitive adhesive sheet test at 300 mm / min. In addition, the measurement at 85 ° C. was performed in the same manner as described above except that the apparatus was used in an environment of 85 ° C. (10% RH or less).

  Here, the test at room temperature and the test at 85 ° C. are also performed independently.

  The adhesive strength is preferably 8 N / 25 mm or more, more preferably 10 N / 25 mm or more, and even more preferably 11 N / 25 mm at room temperature (23 ° C./55% RH).

<Measurement of storage modulus>
About the adhesive layer produced by each Example and the comparative example, the storage elastic modulus of the measurement range of -30 degreeC or more and 150 degrees C or less was measured using the viscoelasticity measuring apparatus (Anton Paar Co., Ltd. make: type | model: MCR300). More specifically, after the produced pressure-sensitive adhesive layer is laminated to a thickness of 400 μm, the sample size is cut to a diameter of 8 mm, the measurement sample is set on a parallel plate jig, and the angular frequency is in a temperature range of −30 ° C. to 150 ° C. The measurement was performed under the conditions of 1 rad / s, normal force 3N, and a temperature rising rate of 5 ° C./min. In addition, the storage elastic modulus of the measurement range of -30 degreeC or more and 150 degrees C or less is measured, and the value of the storage elastic modulus in "-20 degreeC" and "85 degreeC" is shown in the table | surface.

  As shown in Table 3, it can be seen that the optical film pressure-sensitive adhesives of Examples 1 to 29 are excellent in results of durability, bending resistance, and adhesive strength.

  On the other hand, regarding the (meth) acrylic acid ester copolymer, when the molecular weight is below the lower limit of the range of the present invention (Comparative Examples 1 and 6), the structural units derived from the respective components (a1) to (a4) are of the present invention. When it is out of range (Comparative Examples 2, 3, and 5), and when the glass transition temperature exceeds the upper limit of the range of the present invention (Comparative Example 4), each performance of the pressure-sensitive adhesive may be inferior compared to Examples. Recognize.

DESCRIPTION OF SYMBOLS 1 Thin polarizing plate 2 Polycarbonate-type film 3 Polyvinyl alcohol-type adhesive 4 Polarizer 5 Polyvinyl alcohol-type adhesive 6 Phase difference film 7 Conductive layer 8 Protective layer.

Claims (22)

A pressure-sensitive adhesive for optical films comprising a (meth) acrylic acid ester copolymer (A),
The (meth) acrylic acid ester copolymer (A) is
(A1) 9.9% by mass or more and 99.9% by mass or less of a structural unit derived from an alkyl (meth) acrylate monomer;
(A2) a structural unit derived from a macromonomer having a polymerizable functional group, 0.1 mass% or more and 15 mass% or less;
(A3) A structural unit derived from a functional group-containing monomer that is a (meth) acrylic acid derivative monomer having no plurality of radically polymerizable functional groups;
(A4) A structural unit derived from a (meth) acrylic acid ester monomer other than (a1), (a2) and (a3) 0% by mass to 90% by mass;
Including
The total amount of the structural units derived from (a1), (a2), (a3) and (a4) is 100% by mass,
The pressure-sensitive adhesive for optical films, wherein the (meth) acrylic acid ester copolymer has a glass transition temperature of −70 ° C. or more and −57 ° C. or less and a weight average molecular weight of more than 1,000,000 to 2.5 million.   The pressure-sensitive adhesive for optical films according to claim 1, wherein the glass transition temperature is -70 ° C or higher and lower than -60 ° C.   The pressure-sensitive adhesive for optical films according to claim 1 or 2, wherein the weight average molecular weight exceeds 1,200,000.   The (a3) functional group-containing monomer which is a (meth) acrylic acid derivative monomer not having a plurality of radically polymerizable functional groups is a (meth) acrylic acid derivative monomer having a hydroxyl group, an acyl group or an epoxy group, Item 4. The pressure-sensitive adhesive for optical films according to any one of Items 1 to 3.   The said (a1) alkyl (meth) acrylic acid ester monomer is the adhesive for optical films of any one of Claims 1-4 whose carbon number of an alkyl group is 1-18.   The pressure-sensitive adhesive for optical films according to any one of claims 1 to 5, wherein the structural unit derived from the (a1) alkyl (meth) acrylate monomer is 60% by mass or more and 90% by mass or less.   The pressure-sensitive adhesive for optical films according to any one of claims 1 to 6, wherein the (meth) acrylic acid ester copolymer (A) contains a hydroxyl group.   The pressure-sensitive adhesive for optical films according to any one of claims 1 to 7, further comprising a crosslinking agent (B).   9. The optical film according to claim 8, wherein the crosslinking agent (B) is contained in an amount of 0.001 parts by mass to 20 parts by mass with respect to 100 parts by mass of the (meth) acrylic acid ester copolymer (A). Adhesive.   The crosslinking agent (B) is an isocyanate compound, a carbodiimide compound, an oxazoline compound, an epoxy compound, a polyfunctional acrylate monomer, a peroxide, a titanium coupling agent, a zirconium compound, a metal aluminum chelate, a hydrazide compound, and a thermal acid generator. The pressure-sensitive adhesive for optical films according to claim 8 or 9, which is at least one selected from the group consisting of:   The silane coupling agent (C) is any one of Claims 1-10 in which 0.001 mass part or more and 5 mass parts or less are contained with respect to 100 mass parts of the said (meth) acrylic acid ester copolymers (A). Item 1. The pressure-sensitive adhesive for optical films according to item 1.   The adhesive layer formed from the adhesive for optical films of any one of Claims 1-11.   The pressure-sensitive adhesive layer according to claim 12, which has a corona-treated layer or a plasma-treated layer on at least one side. The storage elastic modulus (G ′ (− 20)) at −20 ° C. is 1 × 10 ⁵ Pa or less, and
The adhesive layer of Claim 12 or 13 whose storage elastic modulus (G '(85)) in 85 degreeC is 1 * 10 < ⁴ > Pa or more.   The pressure-sensitive adhesive layer according to any one of claims 12 to 14, wherein G '(-20) / G' (85) is 1.0 or more and 5.0 or less.   The optical member formed by the adhesive layer of any one of Claims 12-15 formed in the at least one side of an optical film.   The optical member of Claim 16 which has an easily bonding layer between the said optical film and the said adhesive layer.   The optical member according to claim 17, wherein the easy adhesion layer is a corona treatment layer, a plasma treatment layer, or a primer layer. The optical film includes a polarizing plate,
The optical member according to claim 16, wherein the polarizing plate has a thickness of 100 μm or less.   The optical film has a conductive layer, and the material forming the conductive layer is indium tin oxide, silver nanowire, indium zinc oxide, indium oxide-zinc oxide composite, polythiophene, carbon nanotube, aluminum zinc oxide, The gallium zinc oxide, fluorine zinc oxide, fluorine indium oxide, antimony tin oxide, fluorine tin oxide and phosphorus tin oxide are at least one selected from the group consisting of oxides. The optical member according to item.   An image display device using at least one optical member according to any one of claims 16 to 20.   The image display device according to claim 21, which is a curved display or a flexible display.