TW201911567A - Multilayer laminate for flexible image display device and flexible image display device - Google Patents

Abstract

The purpose of the present invention is to provide: a layered body for a flexible image display device, including an adhesive layer and an optical film including at least a polarizing membrane, wherein a fold angle that remains when the layered body is bent 180° and then returned to a flat state is in a specific range, whereby the layered body for a flexible image display device has excellent flexure resistance or adhesion and is free of peeling or breakage even from repeated flexure; and a flexible image display device in which the layered body for a flexible image display device is disposed. A layered body for a flexible image display device, including an adhesive layer and an optical film including at least a polarizing membrane, the layered body for a flexible image display device being characterized in that a fold angle that remains when the layered body is bent 180 DEG and then returned to a flat state is 0 DEG to 60 DEG.

Description

Laminated body for flexible image display device, and flexible image display device

The present invention relates to a laminate for a flexible image display device and a flexible image display device provided with the laminate for a flexible image display device, and the laminate for a flexible image display device includes an adhesive layer and at least a polarizing film Of optical film.

BACKGROUND OF THE INVENTION As shown in FIG. 1, an organic EL display device with an integrated touch sensor is provided with an optical laminate 20 on the viewing side of the organic EL display panel 10, and a touch is provided on the viewing side of the optical laminate 20 Control panel 30. The optical layered body 20 includes: a polarizing film 1 having protective films 2-1 and 2-2 bonded to both sides; a retardation film 3; and the polarizing film 1 is provided on the viewing side of the retardation film 3. In addition, the touch panel 30 has a structure in which transparent conductive films 4-1 and 4-2 are arranged via a separator 7, and the transparent conductive films 4-1 and 4-2 have base film 5-1 and 5-2 and A structure in which transparent conductive layers 6-1 and 6-2 are laminated (refer to, for example, Patent Document 1).

In addition, it is expected to realize an organic EL display device that is more portable and bendable.

Prior Art Literature Patent Literature Patent Literature 1: Japanese Patent Laid-Open No. 2014-157745

SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION However, the conventional organic EL display device shown in Patent Document 1 is not designed in consideration of the bending function. As long as the plastic film is used as the substrate of the organic EL display panel, the organic EL display panel can be given flexibility. And when the plastic film is used in the touch panel and incorporated into the organic EL display panel, the organic EL display panel can still be given flexibility. However, there is a problem that the optical thin film including the conventional polarizing film and the like laminated on the organic EL display panel hinders the flexibility of the organic EL display device.

In addition, in the conventional organic EL display device, when it is repeatedly bent, slight strain, peeling, and cracking (fracture) may occur between or between layers of the optical film and the adhesive layer constituting the organic EL display device. The problem occurs.

Therefore, an object of the present invention is to provide a laminate for a flexible image display device and a flexible image display device provided with the laminate for a flexible image display device, the laminate for a flexible image display device including an adhesive layer With an optical film containing at least a polarizing film, and the layered body is bent 180° and then flattened, the remaining bending angle is within a certain range, so it will not peel off and break in the face of repeated flexure, thus Has excellent resistance to flexure and adhesion.

Means for Solving the Problem The laminated body for flexible image display devices of the present invention is characterized by comprising an adhesive layer and an optical film containing at least a polarizing film, and after bending the laminated body by 180° and then returning it to flat The remaining bending angle is 0°~60°.

The laminate for a flexible image display device of the present invention has a storage elastic modulus G'of the adhesive layer at 25°C of 1×10 ⁵ Pa or less, and represents tanδ of the glass transition temperature (Tg) of the adhesive layer The peak value is preferably 3 or less.

The laminate for a flexible image display device of the present invention preferably has a loss elastic modulus G'' of the adhesive layer at 25° C. of 1×10 ⁵ Pa or less.

The laminate for a flexible image display device of the present invention preferably has the aforementioned adhesive layer of 2 or more and 5 or less.

The laminate for a flexible image display device of the present invention is preferably formed by the adhesive layer containing an adhesive composition containing a (meth)acrylic polymer.

The flexible image display device of the present invention preferably includes the laminate for flexible image display device and an organic EL display panel, and the laminate for flexible image display device is arranged on the viewing side of the organic EL display panel.

The flexible image display device of the present invention is preferably provided with a window on the viewing side of the laminate for the flexible image display device.

Effect of the Invention According to the present invention, a laminate for a flexible image display device can be produced, and a flexible image display device provided with the laminate for a flexible image display device described above is useful; the flexible image display device The laminated body contains an adhesive layer and an optical film containing at least a polarizing film, and the bending angle remaining after the laminated body is bent 180° and then flattened is within a specific range, so it is also faced with repeated deflection No peeling and breaking, so it has excellent flex resistance and adhesion.

Hereinafter, embodiments of the optical film, the laminate for a flexible image display device, and the flexible image display device of the present invention will be described in detail with reference to the drawings and the like.

Forms for Carrying Out the Invention The present invention will be described in detail below, but the present invention is not limited to the following embodiments, and can be arbitrarily changed and implemented without departing from the gist of the present invention.

[Laminate for Flexible Image Display Device] The laminate for a flexible image display device of the present invention is characterized by including an adhesive layer and an optical film.

[Optical film] The laminated body for a flexible image display device of the present invention is characterized by including an optical film containing at least a polarizing film, and the optical film means that in addition to the polarizing film, a protective film formed of, for example, a transparent resin material and Thin films such as retardation films. Furthermore, in the present invention, the following configuration is referred to as an optical laminate: the optical film includes the polarizing film, a protective film of a transparent resin material included in the first surface of the polarizing film, and the polarizing film and the first The retardation film on the second surface that differs from one surface. In addition, the aforementioned optical film does not include an adhesive layer such as a first adhesive layer described later.

The thickness of the aforementioned optical film is preferably 92 μm or less, preferably 60 μm or less, and more preferably 10-50 μm. If it is within the aforementioned range, it will not hinder the deflection and is the preferred form.

As long as the characteristics of the present invention are not impaired, a protective film (not shown in the drawings) may be adhered through an adhesive (layer) on at least one side of the polarizing film. An adhesive can be used for the subsequent treatment of the polarizing film and the protective film. Examples of the adhesive include isocyanate adhesives, polyvinyl alcohol adhesives, gelatin adhesives, vinyl emulsion adhesives, and water-based polyesters. The aforementioned adhesive is usually used as an adhesive composed of an aqueous solution, and usually contains 0.5 to 60% by weight of a solid component. In addition to the above, the adhesive of the polarizing film and the protective film may also include an ultraviolet curing adhesive, an electron beam curing adhesive, and the like. The adhesive for the electron beam hardening type polarizing film can exhibit good adhesion to the various protective films described above. In addition, the adhesive used in the present invention may contain a metal compound filler. In addition, in the present invention, a polarizing film and a protective film laminated with a transmission adhesive (layer) may be called a polarizing film (polarizing plate).

<Polarizing film> The polarizing film (also called polarizer) contained in the optical film of the present invention can use a polyvinyl alcohol (PVA) resin, and the polyvinyl alcohol (PVA) resin is stretched in the air (dry stretch) ) Or an extension step such as an extension step in boric acid water, and has directed iodine.

The manufacturing method of the polarizing film is typically represented by a manufacturing method (single layer stretching method) described in Japanese Patent Laid-Open No. 2004-341515. The manufacturing method includes a step of dyeing a single layer of a PVA-based resin and a step of stretching. Examples include Japanese Patent Laid-Open No. 51-069644, Japanese Patent Laid-Open No. 2000-338329, Japanese Patent Laid-Open No. 2001-343521, International Publication No. 2010/100917, Japanese Patent Laid-Open No. 2012-073563, The manufacturing method described in Japanese Patent Laid-Open No. 2011-2816 includes a step of extending a PVA-based resin layer and an extending resin base material in a state of a laminate, and a step of dyeing. As long as this manufacturing method is used, even if the PVA-based resin layer is very thin, it is supported by the resin substrate for stretching, so that it can be stretched without causing a defect such as breakage due to stretching.

Among the manufacturing methods including the step of extending in the state of the laminate and the step of dyeing, there are the aforementioned Japanese Patent Laid-Open No. 51-069644, Japanese Patent Laid-Open No. 2000-338329, Japanese Patent Laid-Open No. 2001-343521 The aerial extension (dry extension) method described. In addition, it is preferable that the polarizing performance can be improved by extending at a high magnification, as described in International Publication No. 2010/100917 and Japanese Unexamined Patent Publication No. 2012-073563, including a method of extending in a boric acid aqueous solution. In particular, a manufacturing method (two-stage stretching method) including the step of performing air-assisted stretching before stretching in a boric acid aqueous solution, such as Japanese Patent Laid-Open No. 2012-073563, is preferred. In addition, as described in Japanese Patent Application Laid-Open No. 2011-2816, a manufacturing method (excessive dyeing and decoloring method) is also preferable. In this manufacturing method, after the PVA-based resin layer and the extending resin base material are extended in the state of a laminate, the PVA The resin layer is over-dyed, and then it is decolorized. The polarizing film contained in the optical film of the present invention can be made into a polarizing film composed of a polyvinyl alcohol-based resin orientated with iodine as described above, and is extended by a two-stage extension consisting of air-assisted extension and boric acid underwater extension Steps are extended. In addition, the polarizing film may be made of a polarizing film composed of a polyvinyl alcohol-based resin orientated with iodine as described above, and the laminated body of the stretched PVA-based resin layer and the stretching resin base material is over-dyed, which It is then decolorized and made.

The thickness of the polarizing film is 20 μm or less, preferably 12 μm or less, preferably 9 μm or less, and more preferably 1 to 8 μm, particularly preferably 3 to 6 μm. If it is within the aforementioned range, it will not hinder the deflection and is the preferred form.

<Retardation film> The optical film used in the present invention may include a retardation film, and the aforementioned retardation film (also called a retardation film) may be obtained by extending a polymer film or by orienting and fixing a liquid crystal material Changer. In this specification, the retardation film refers to one having birefringence in the plane and/or in the thickness direction.

Examples of the retardation film include an antireflection retardation film (refer to Japanese Patent Laid-Open Nos. 2012-133303 [0221], [0222], [0228]), and a retardation film for viewing angle compensation (refer to Japanese Laid-Open Patent No. 2012-133303 Bulletins [0225], [0226]), tilt alignment retardation films for viewing angle compensation (refer to Japanese Patent Laid-Open No. 2012-133303 [0227]), etc.

The retardation film is not particularly limited as long as it has substantially the above-mentioned functions, such as a retardation value, an arrangement angle, a three-dimensional birefringence, a single layer or multiple layers, and a known retardation film can be used.

The thickness of the aforementioned retardation film is preferably 20 μm or less, preferably 10 μm or less, and more preferably 1 to 9 μm, particularly preferably 3 to 8 μm. If it is within the aforementioned range, it will not hinder the deflection and is the preferred form.

<Protective Film> The optical film used in the present invention may include a protective film formed of a transparent resin material, and the protective film (also referred to as a transparent protective film) may use cycloolefin-based resins such as norbornene-based resin, poly Olefin resins such as ethylene and polypropylene, polyester resins, (meth)acrylic resins, etc.

The thickness of the protective film is preferably 5 to 60 μm, more preferably 10 to 40 μm, and more preferably 10 to 30 μm, and surface treatment layers such as an anti-glare layer and an anti-reflection layer can be appropriately provided. If it is within the aforementioned range, it will not hinder the deflection and is the preferred form.

[Adhesive layer] The laminate for flexible image display devices of the present invention is characterized in that it is a laminate for flexible image display devices including an adhesive layer and an optical film containing at least a polarizing film. In addition, the adhesive layer may be one layer, but in addition to the optical film, in order to laminate a transparent conductive film, an organic EL display panel, a window, a decorative printed film, a retardation layer, a protective film, etc., there may be more than two layers When the multilayer body for a sexual image display device has multiple adhesive layers such as a first adhesive layer and a second adhesive layer, for example, refer to FIG. 2 and the like). When there are multiple adhesive layers, it is preferable to have 2 or more layers and 5 or less layers. If there are more than 5 layers, the thickness of the entire laminate becomes thicker, and the strain difference between the outermost layer and the innermost layer of the flexure of the laminate becomes large, and it is easy to peel or break, which is not good.

[First Adhesive Layer] Among the adhesive layers used in the laminate for flexible image display devices of the present invention, the first adhesive layer is preferably disposed on the surface of the protective film that is in contact with the polarizing film with respect to the protective film On the opposite side (see Figure 2).

Examples of the adhesive layer constituting the first adhesive layer used in the laminate for flexible image display devices of the present invention include acrylic adhesives, rubber adhesives, vinyl alkyl ether adhesives, polysiloxane adhesives, Polyester-based adhesives, polyamide-based adhesives, urethane-based adhesives, fluorine-based adhesives, epoxy-based adhesives, polyether-based adhesives, etc. In addition, the adhesive constituting the adhesive layer may be used alone or in combination of two or more. However, from the viewpoint of transparency, processability, durability, adhesion, and flex resistance, it is preferable to use an acrylic adhesive (composition) containing a (meth)acrylic polymer alone.

<(Meth)acrylic polymer> When an acrylic adhesive is used as the adhesive composition, it is preferable to contain (meth)acrylic acid containing a linear or branched C1-C30 alkyl group (Meth)acrylic polymer whose monomer is a monomer unit. Using the aforementioned (meth)acrylic monomer having a linear or branched C1-C30 alkyl group, an adhesive layer excellent in flexibility can be obtained. In addition, (meth)acrylic polymer in the present invention refers to acrylic polymer and/or methacrylic polymer, and methacrylate refers to acrylate and/or methacrylate.

Specific examples of the (meth)acrylic monomer having a linear or branched C 1-30 alkyl group constituting the main skeleton of the (meth)acrylic polymer include (meth) ) Methyl acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, secondary butyl (meth) acrylate, tertiary butyl (meth) acrylate, isobutyl (meth) acrylate , N-pentyl (meth)acrylate, isoamyl (meth)acrylate, n-hexyl (meth)acrylate, isohexyl (meth)acrylate, isoheptyl (meth)acrylate, (meth)acrylic acid 2 -Ethylhexyl, n-octyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, n-decyl (meth)acrylate , Isodecyl (meth)acrylate, n-dodecyl (meth)acrylate (lauryl (meth)acrylate), n-tridecyl (meth)acrylate, n-tetradecyl (meth)acrylate, etc., From the viewpoint of flexibility, (meth)acrylic monomers with linear or branched C6-C30 alkyl groups (hereinafter sometimes referred to as "having long-chain alkyl groups" (Meth)acrylic monomer") is preferred, n-dodecyl (meth)acrylate (lauryl (meth)acrylate) is more preferred. By using the aforementioned (meth)acrylic monomer having a long-chain alkyl group, the entanglement of the polymer can be reduced, making it susceptible to deformation by minute strains, and it is preferable for flexibility. In addition, from the viewpoint of flexibility and adhesion at low temperatures, it is also appropriate to use (meth)acrylic monomers with a homopolymer having a glass transition temperature (Tg) of -70 to -20°C. It is better to use 2-ethylhexyl acrylate. Moreover, the said (meth)acrylic monomer can use 1 type or 2 or more types. In addition, the so-called "minimal strain" refers to a laminate for a flexible image display device. For example, there is a strain of about ±0 to 10% for a bending direction of 3 mm centered on the apex of the flexure, and "+" indicates stretching Strain in the direction, "-" indicates the strain in the compression direction. Generally speaking, the outside of the bend (convex side) will increase the strain in the tensile direction of "+", while the inside of the bend (concave side) will increase the strain in the compression direction of "-". In addition, the flexed laminate There will be a neutral axis where the strain stress is zero anywhere inside.

The aforementioned (meth)acrylic monosystem having a linear or branched C1-C30 alkyl group constitutes the main component of the total monomers of the (meth)acrylic polymer. Here, the main component means a (meth)acrylic monomer having a linear or branched alkyl group having 1 to 30 carbon atoms among the total monomers constituting the (meth)acrylic polymer. It is preferably 50 to 100% by weight, more preferably 80 to 100% by weight, and still more preferably 90 to 99.9% by weight, particularly preferably 94 to 99.9.

The monomer component constituting the (meth)acrylic polymer may contain copolymerizable copolymerizable components in addition to the (meth)acrylic monomer having a linear or branched C1-C30 alkyl group. Monomer (copolymerizable monomer). In addition, the copolymerizable monomer may be used alone or in combination of two or more.

The aforementioned copolymerizable monomer is not particularly limited, but preferably contains a (meth)acrylic polymer containing a hydroxyl group-containing monomer having a reactive functional group. By using the aforementioned hydroxyl group-containing monomer, an adhesive layer excellent in adhesion and flexibility can be obtained. The aforementioned hydroxy-containing single system 1 contains a hydroxy group in its structure and contains a polymerizable unsaturated double bond such as (meth)acryloyl group and vinyl group.

Specific examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 6-(meth)acrylate. Hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, etc. -Hydroxymethylcyclohexyl)-methacrylate and the like. From the viewpoint of durability and adhesion, the aforementioned hydroxyl group-containing monomers are preferably 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate. In addition, the aforementioned hydroxyl group-containing monomer may be used in one kind or two or more kinds.

In addition, the copolymerizable monomer may include monomers such as a carboxyl group-containing monomer having a reactive functional group, an amine group-containing monomer, and an amide group-containing monomer. From the viewpoint of humidification and adhesion under high temperature environment, it is better to use these monomers.

When an acrylic adhesive is used as the adhesive composition, a (meth)acrylic polymer containing a carboxyl group-containing monomer having a reactive functional group as a monomer unit may be contained. By using the carboxyl group-containing monomer, an adhesive layer excellent in adhesion under humidification and high temperature environment can be produced. The aforementioned carboxyl-containing single system 1 contains a carboxyl group in its structure and contains a polymerizable unsaturated double bond such as (meth)acryloyl group and vinyl group.

Specific examples of the carboxyl group-containing monomer include (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid.

When an acrylic adhesive is used as the adhesive composition, it may contain a (meth)acrylic polymer containing an amine group-containing monomer having a reactive functional group as a monomer unit. By using the aforementioned amine group-containing monomer, an adhesive layer excellent in adhesion in a humidified and high-temperature environment can be produced. The aforementioned amine group-containing single system 1 is a compound containing an amine group in its structure and containing a polymerizable unsaturated double bond such as (meth)acryloyl group and vinyl group.

Specific examples of the aforementioned amine group-containing monomer include N,N-dimethylamine ethyl (meth)acrylate, N,N-dimethylaminepropyl (meth)acrylate, and the like.

When an acrylic adhesive is used as the aforementioned adhesive composition, it may contain a (meth)acrylic polymer containing an amine group-containing monomer having a reactive functional group as a monomer unit. By using the aforementioned amide group-containing monomer, an adhesive layer excellent in adhesion can be produced. The above-mentioned single system containing an amide group contains a compound having an amide group in its structure and a polymerizable unsaturated double bond such as (meth)acryl amide group and vinyl group.

Specific examples of the aforementioned amide group-containing monomers include (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide , N-isopropylacrylamide, N-methyl (meth)acrylamide, N-butyl (meth)acrylamide, N-hexyl (meth)acrylamide, N-methylol (Meth)acrylamide, N-hydroxymethyl-N-propane (meth)acrylamide, aminomethyl (meth)acrylamide, amine ethyl (meth)acrylamide, mercaptomethyl (Meth) acrylamide, mercaptoethyl (meth) acrylamide and other acrylamide monomers; N-(meth)acrylamide morpholin, N-(meth)acrylamide piperidine , N-(meth)acryloyl pyrrolidine and other N-acryloyl heterocyclic monomers; N-vinylpyrrolidone, N-vinyl-ε-caprolactam and other N-vinyl acylamides Amine monomers, etc.

In addition, the aforementioned comonomers include polyfunctional monomers (multifunctional monomers). If it contains multifunctional monomers, crosslinking effect can be obtained through polymerization, and the gel fraction can be easily adjusted and the cohesive force can be improved. Therefore, the cutting will become easier and the workability will be improved. Also, during deflection (especially under high temperature environment), it can prevent peeling due to cohesive failure of the adhesive layer. The polyfunctional monomer is not particularly limited, and examples thereof include hexanediol di(meth)acrylate (1,6-hexanediol di(meth)acrylate), butanediol di(meth)acrylate, (Poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, neopentaerythritol di(meth)acrylate, Neopentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, Multifunctional acrylates such as allyl (meth)acrylate, vinyl (meth)acrylate, epoxy acrylate, polyester acrylate, urethane acrylate, or divinylbenzene, etc. The ester is preferably 1,6-hexanediol diacrylate and dipentaerythritol hexa(meth)acrylate. In addition, the polyfunctional monomer may be used alone or in combination of two or more.

As the monomer unit constituting the (meth)acrylic polymer, the blending ratio (total amount) of the monomer having a reactive functional group and the polyfunctional monomer is Among the total monomers, it is preferably 20% by weight or less, more preferably 10% by weight or less, and more preferably 0.01-8% by weight, particularly preferably 0.01-5% by weight, and most preferably 0.05-3% by weight. If it exceeds 20% by weight, the number of cross-linking points will increase and the adhesive (layer) will lose its flexibility, so the stress relaxation property will tend to be poor.

When an acrylic adhesive is used as the adhesive composition, as the monomer unit, in addition to the monomer having a reactive functional group and the polyfunctional monomer, it may be within a range that does not impair the effects of the present invention Import other comonomers.

In addition, the aforementioned other comonomers include, for example, alkoxyalkyl (meth)acrylates [e.g., 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, (meth Group) methoxytriethylene glycol acrylate, 3-methoxypropyl (meth)acrylate, 3-ethoxypropyl (meth)acrylate, 4-methoxybutyl (meth)acrylate, (meth Group) 4-ethoxybutyl acrylate, etc.]; epoxy group-containing monomers [for example, glycidyl (meth)acrylate, methylglycidyl (meth)acrylate, etc.]; Monomers [such as sodium vinylsulfonate, etc.]; monomers containing phosphoric acid groups; (meth)acrylates with alicyclic hydrocarbon groups [such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate , Isobornyl (meth)acrylate, etc.]; (meth)acrylates with aromatic hydrocarbon groups [eg phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, benzyl (meth)acrylate) Etc.]; vinyl esters [such as vinyl acetate, vinyl propionate, etc.]; aromatic vinyl compounds [such as styrene, vinyl toluene, etc.]; olefins or dienes [such as ethylene, propylene, butadiene , Isoprene, isobutylene, etc.]; vinyl ethers [such as vinyl alkyl ethers]; vinyl chloride, etc.

The blending ratio of the aforementioned other comonomers is not particularly limited, but in the total monomers constituting the (meth)acrylic polymer, it is preferably 30% by weight or less, more preferably 10% by weight or less, and does not contain more good. If it exceeds 30% by weight, especially when a (meth)acrylic monomer is used, the reaction point of the adhesive layer and other layers (film, base material) will decrease, and the adhesion tends to decrease.

The adhesive layer is formed of an adhesive composition, and the adhesive composition may be an adhesive composition having any form, such as emulsion type, solvent type (solution type), active energy ray hardening type, Hot melt type (hot melt type) and the like. Among them, the adhesive composition is preferably a solvent-based adhesive composition or an active energy ray-curable adhesive composition.

The solvent-based adhesive composition preferably includes an adhesive composition containing the (meth)acrylic polymer as an essential component. Further, the active energy ray-curable adhesive composition preferably includes, for example, an adhesive containing a mixture (monomer mixture) of a monomer component constituting the (meth)acrylic polymer or a partial polymer as an essential component. Composition. In addition, the "partial polymer" means a composition in which one or more of the monomer components contained in the monomer mixture have been partially polymerized. In addition, "monomer mixture" is defined as a case where only one kind of monomer component is included.

From the viewpoint of productivity, the impact on the environment, and the ease of producing a thick adhesive layer, the above-mentioned adhesive composition is particularly preferably a monomer component containing a (meth)acrylic polymer. Active energy ray-curable adhesive composition in which a mixture (monomer mixture) or a part of the polymer is an essential component.

The (meth)acrylic polymer can be obtained by polymerizing the monomer component. More specifically, the monomer component, the monomer mixture, or a part of the polymer thereof can be obtained by polymerizing a well-known method. Examples of the polymerization method include solution polymerization, emulsification polymerization, bulk polymerization, polymerization by heat or active energy ray irradiation (thermal polymerization, active energy ray polymerization), and the like. Among them, from the viewpoint of transparency, water resistance, cost, etc., solution polymerization and active energy ray polymerization are preferred. In addition, from the viewpoint of inhibiting polymerization inhibition by oxygen, the polymerization should preferably be carried out without contact with oxygen. For example, the polymerization is preferably carried out under a nitrogen atmosphere, or the oxygen is separated by a peeling film (separator) to carry out the polymerization. In addition, the obtained (meth)acrylic polymer may be any of a random copolymer, a block copolymer, and a graft copolymer.

The active energy rays irradiated when performing the above-mentioned active energy ray polymerization (photopolymerization) include, for example, free radiation such as α-rays, β-rays, γ-rays, neutron rays, and electron rays, or ultraviolet rays, among which ultraviolet rays are particularly preferred. In addition, the irradiation energy, irradiation time, irradiation method, etc. of the active energy rays are not particularly limited as long as they can activate the photopolymerization initiator to promote the reaction of the monomer components.

Various general solvents can be used for the aforementioned solution polymerization. Examples of the solvent include esters such as ethyl acetate and n-butyl acetate; aromatic hydrocarbons such as toluene and benzene; aliphatic hydrocarbons such as n-hexane and n-heptane; cyclohexane and methylcyclohexane Alicyclic hydrocarbons; organic solvents such as methyl ethyl ketone, methyl isobutyl ketone, etc. In addition, the aforementioned solvents may be used alone or in combination of two or more.

In addition, when performing polymerization, depending on the type of polymerization reaction, a polymerization initiator such as a photopolymerization initiator (photoinitiator) and a thermal polymerization initiator may be used. In addition, the aforementioned polymerization initiator may be used alone or in combination of two or more.

The photopolymerization initiator is not particularly limited, and examples thereof include benzoin ether-based photopolymerization initiators, acetophenone-based photopolymerization initiators, α-ketoalcohol-based photopolymerization initiators, and aromatic sulfonamides. Chlorine-based photopolymerization initiator, photoactive oxime-based photopolymerization initiator, benzoin-based photopolymerization initiator, benzyl-based photopolymerization initiator, diphenyl ketone-based photopolymerization initiator, condensation Ketone photopolymerization initiator, 9-oxosulfur It is a photopolymerization initiator.

Examples of the benzoin ether-based photopolymerization initiator include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, and 2,2-bis Methoxy-1,2-diphenylethyl-1-one, anisole methyl ether, etc. Examples of the acetophenone-based photopolymerization initiator include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, and 1-hydroxycyclohexylphenyl ketone , 4-phenoxydichloroacetophenone, 4-(tertiary butyl)dichloroacetophenone, etc. Examples of the α-ketol alcohol photopolymerization initiator include 2-methyl-2-hydroxyphenylacetone, 1-[4-(2-hydroxyethyl)benzene]-2-methylpropan-1-one, etc. . Examples of the aromatic sulfonyl chloride-based photopolymerization initiator include 2-naphthalene sulfonyl chloride. Examples of the photoactive oxime-based photopolymerization initiator include 1-benzene-1,1-propanedione-2-(o-ethoxycarbonyl)-oxime. Examples of the benzoin-based photopolymerization initiator include benzoin. Examples of the benzyl-based photopolymerization initiator include benzyl. Examples of the diphenyl ketone-based photopolymerization initiator include diphenyl ketone, benzoyl benzoic acid, 3,3'-dimethyl-4-methoxydiphenyl ketone, and polyvinyl diphenyl Ketone, α-hydroxycyclohexyl phenyl ketone, etc. Examples of the ketal-based photopolymerization initiator include benzyl dimethyl ketal. 9-oxosulfur Examples of the photopolymerization initiator include 9-oxysulfur , 2-chloro9-oxysulfur , 2-Methyl 9-oxysulfur , 2,4-Dimethyl 9-oxysulfur , Isopropyl 9-oxysulfur , 2,4-Diisopropyl 9-oxysulfur 、Dodecyl 9-oxysulfur Wait.

The amount of the photopolymerization initiator used is not particularly limited, but it is preferably 0.01 to 1 part by weight, more preferably 0.05 to 0.5 part by weight, relative to 100 parts by weight of the total monomer component.

Examples of the polymerization initiator used in the aforementioned solution polymerization include azo-based polymerization initiators and peroxide-based polymerization initiators (such as dibenzoyl peroxide, tertiary butyl maleate peroxide, etc.) , Redox polymerization initiator, etc. Among them, the azo polymerization initiator disclosed in Japanese Patent Laid-Open No. 2002-69411 is preferred. Examples of the azo-based polymerization initiator include 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis-2-methylbutyronitrile, and 2,2'-azobis (2-Methylpropionic acid) dimethyl ester, 4,4'-azobis-4-cyanovaleric acid, etc.

The amount of the azo-based polymerization initiator used is not particularly limited, but it is preferably 0.05 to 0.5 parts by weight, more preferably 0.1 to 0.3 parts by weight relative to 100 parts by weight of the total monomer components.

In addition, the multifunctional monomer (multifunctional acrylate) used as the comonomer can also be used in a solvent-based or active energy ray-curable adhesive composition. However, for example, the above-mentioned multifunctional monomer (multifunctional acrylic Ester) is mixed with the photopolymerization initiator described above in a solvent-based adhesive composition for use, and the active energy ray hardening is performed after thermal drying.

In the present invention, when the (meth)acrylic polymer used in the solvent-based adhesive composition is used, a weight average molecular weight (Mw) in the range of 1 million to 2 million is generally used. When considering durability, especially heat resistance and flexibility, it is preferably 1.2 million to 2 million, preferably 1.4 million to 1.8 million. If the weight average molecular weight is less than 1 million, when polymer chains are cross-linked to ensure durability, the number of cross-linking points will increase as compared to those with a weight average molecular weight of 1 million or more, resulting in an adhesive (layer) It loses its flexibility, so it cannot alleviate the strain on the outer side of the bend (convex side) and the inner side of the bend (concave side) generated between the layers (films) during deflection, making the layers prone to breakage. In addition, if the weight average molecular weight is greater than 2.5 million, a large amount of dilution solvent is required to adjust the viscosity for coating, which increases the cost, which is not good, and the (meth)acrylic polymer produced The entanglement of the polymer chains becomes complicated, so that the flexibility is deteriorated, so that the layers (films) are easily broken when flexed. In addition, the weight average molecular weight (Mw) refers to a value measured by GPC (gel permeation chromatography; Gel Permeation Chromatography) and calculated in terms of polystyrene.

<(Meth)acrylic oligomer> The adhesive composition may contain a (meth)acrylic oligomer. The (meth)acrylic oligomer preferably uses a weight average molecular weight (Mw) smaller than the (meth)acrylic polymer. By using the (meth)acrylic oligomer, the aforementioned (Meth)acrylic oligomers exist between the (meth)acrylic polymers to reduce the entanglement of the (meth)acrylic polymers, so that they are easily deformed by small strains and flexed. Sex is the best form.

Examples of monomers constituting the (meth)acrylic oligomer include: methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and isopropyl (meth)acrylate , Butyl (meth)acrylate, isobutyl (meth)acrylate, secondary butyl (meth)acrylate, tertiary butyl (meth)acrylate, amyl (meth)acrylate, (meth) Isoamyl acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, Nonyl (meth)acrylate, Isononyl (meth)acrylate, Decyl (meth)acrylate, Isodecyl (meth)acrylate, Undecyl (meth)acrylate, Dodecyl (meth)acrylate (Meth)acrylic acid alkyl esters such as esters; (meth)acrylic acid and lipids such as cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentyl (meth)acrylate Esters of cyclic alcohols; aryl (meth)acrylates such as phenyl (meth)acrylate and benzyl (meth)acrylate; (meth)acrylates made from alcohols derived from terpene compounds . Such (meth)acrylates can be used alone or in combination of two or more.

The aforementioned (meth)acrylic oligomer preferably contains an acrylic monomer having a relatively bulky structure represented by the following as a monomer unit: isobutyl (meth)acrylate or tertiary butyl (meth)acrylate This type of alkyl group has a branched structure of (meth)acrylic acid alkyl esters; (meth)acrylic acid cyclohexyl ester, (meth)acrylic acid isobutyl ester (meth)acrylic acid dicyclopentyl ester (method Base) esters of acrylic acid and alicyclic alcohols; aryl (meth)acrylates such as phenyl (meth)acrylate or benzyl (meth)acrylate and the like (meth)acrylates having a cyclic structure. Making the (meth)acrylic oligomer have such a large structure can further improve the adhesiveness of the adhesive layer. Especially from the viewpoint of a large structure, those with a ring structure have a high effect, and those with multiple rings have a higher effect. In addition, when synthesizing (meth)acrylic oligomers or when forming an adhesive layer, if ultraviolet rays are used, it is difficult to hinder the polymerization. From this point of view, those having a saturated bond are suitable, and the alkyl group has a branched structure. An alkyl (meth)acrylate or an ester with an alicyclic alcohol is used as a monomer constituting the (meth)acrylic oligomer.

From the above viewpoint, more suitable (meth)acrylic oligomers include, for example, copolymers of butyl acrylate (BA) and methyl acrylate (MA) and acrylic acid (AA), and cyclohexyl methacrylate ( CHMA) copolymer with isobutyl methacrylate (IBMA), copolymer of cyclohexyl methacrylate (CHMA) and isobornyl methacrylate (IBXMA), cyclohexyl methacrylate (CHMA) and propylene Copolymer of Acetylformin (ACMO), Copolymer of cyclohexyl methacrylate (CHMA) and diethylacrylamide (DEAA), 1-adamantyl acrylate (ADA) and methyl methacrylate (MMA) copolymer, copolymer of dicyclopentyl methacrylate (DCPMA) and isobornyl methacrylate (IBXMA), dicyclopentyl methacrylate (DCPMA), cyclohexyl methacrylate (CHMA ), isobornyl methacrylate (IBXMA), isobornyl acrylate (IBXA), copolymer of cyclopentyl methacrylate (DCPMA) and methyl methacrylate (MMA), dicyclopentyl acrylate (DCPA) , Each homopolymer of 1-adamantyl methacrylate (ADMA), 1-adamantyl acrylate (ADA), etc.

The polymerization method of the (meth)acrylic oligomer is the same as that of the (meth)acrylic polymer. Examples include solution polymerization, emulsification polymerization, bulk polymerization, emulsification polymerization, heat application, or irradiation of active energy rays. Polymerization (thermal polymerization, active energy ray polymerization), etc. Among them, from the viewpoint of transparency, water resistance, cost, etc., solution polymerization and active energy ray polymerization are preferred. In addition, the obtained (meth)acrylic oligomer may be any of a random copolymer, a block copolymer, and a graft copolymer.

The (meth)acrylic oligomer can be used for the solvent-based adhesive composition and the active energy ray-curable adhesive composition in the same manner as the (meth)acrylic polymer. For example, as the aforementioned active energy ray-curable adhesive composition, the aforementioned (method) can be mixed into the mixture (monomer mixture) of the monomer components constituting the (meth)acrylic polymer or a part of the polymer. Base) acrylic oligomers. When the aforementioned (meth)acrylic oligomer is dissolved in a solvent, it can be dried by heat to volatilize the solvent in the adhesive composition, and then the active energy ray hardening is completed to prepare an adhesive layer.

The weight average molecular weight (Mw) of the (meth)acrylic oligomer used in the solvent-based adhesive composition is preferably 1000 or more, and preferably 2000 or more, more preferably 3000 or more, and particularly preferably 4000 or more. In addition, the weight average molecular weight (Mw) of the (meth)acrylic oligomer is preferably 30,000 or less, and preferably 15,000 or less, more preferably 10,000 or less, and particularly preferably 7,000 or less. By adjusting the weight average molecular weight (Mw) of the (meth)acrylic oligomer to the aforementioned range, for example, when used in combination with the (meth)acrylic polymer, the (meth)acrylic oligomer can be used The presence of the polymer in the aforementioned (meth)acrylic polymer reduces the entanglement of the (meth)acrylic polymer, makes the adhesive layer easily deform to small strains, and can reduce the strain applied to other layers In order to suppress the cracking of each layer and the peeling between the adhesive layer and other layers, it is the best form. In addition, the weight average molecular weight (Mw) of the (meth)acrylic oligomer is the same as that of the (meth)acrylic polymer, which means measured by GPC (gel permeation chromatography; Gel Permeation Chromatography) and The calculated value of polystyrene conversion.

When the (meth)acrylic oligomer is used as the adhesive composition, the blending amount is not particularly limited, but it is preferably 70 parts by weight or less relative to 100 parts by weight of the (meth)acrylic polymer. It is more preferably 1 to 70 parts by weight, more preferably 2 to 50 parts by weight, and more preferably 3 to 40 parts by weight. By adjusting the blending amount of the (meth)acrylic oligomer to the aforementioned range, the (meth)acrylic oligomer can be appropriately present between the (meth)acrylic polymer and ( The entanglement of the meth)acrylic polymer is reduced, so that the adhesive layer is easily deformed by small strains, and the strain applied to other layers can be reduced, thereby suppressing the cracking of each layer and the peeling between the adhesive layer and other layers And so on, and is the better form.

<Crosslinking agent> The adhesive composition of the present invention may contain a crosslinking agent. As the crosslinking agent, an organic crosslinking agent or a multifunctional metal chelate compound can be used in any of the solvent-based or active energy ray-curable adhesive composition. Examples of the organic-based crosslinking agent include isocyanate-based crosslinking agents, peroxide-based crosslinking agents, epoxy-based crosslinking agents, and imine-based crosslinking agents. The multifunctional metal chelate compound is a product in which a multivalent metal and an organic compound are covalently bonded or coordinately bonded. Examples of polyvalent metal atoms include Al, Cr, Zr, Co, Cu, Fe, Ni, V, Zn, In, Ca, Mg, Mn, Y, Ce, Sr, Ba, Mo, La, Sn, Ti, and the like. Atoms that can be covalently bonded or coordinately bonded in organic compounds include oxygen atoms and the like, and organic compounds include alkyl esters, alcohol compounds, carboxylic acid compounds, ether compounds, and ketone compounds. When it is a solvent-based adhesive composition, it is preferably a peroxide-based crosslinking agent or an isocyanate crosslinking agent, and among them, a peroxide-based crosslinking agent is preferably used. The peroxide-based cross-linking agent is, for example, by removing hydrogen from the side chain of the (meth)acrylic polymer to generate free radicals, and the side chains of the (meth)acrylic polymer are carried out with each other. Cross-linking, so compared to the use of isocyanate-based cross-linking agent (such as multifunctional isocyanate-based cross-linking agent) for cross-linking, the cross-linked state is relatively gentle, and can maintain its easy to small strain deformation At the same time, it improves the cohesive force, so that it can suppress the cracking of each layer and the peeling between the adhesive layer and other layers, which is the best form. In addition, isocyanate-based crosslinking agents (especially trifunctional isocyanate-based crosslinking agents) are ideal from the viewpoint of durability, and peroxide-based crosslinking agents and isocyanate-based crosslinking agents (especially difunctional The isocyanate-based crosslinking agent) is preferable from the viewpoint of flexibility. Both the peroxide-based cross-linking agent and the difunctional isocyanate-based cross-linking agent will form a soft two-dimensional cross-linking, while the tri-functional isocyanate-based cross-linking agent will form a stronger three-dimensional cross-linking. When flexing, softer cross-linking, that is, two-dimensional cross-linking, is more advantageous. However, if only two-dimensional cross-linking is used, the durability will be poor and flaking is likely to occur. Therefore, the mixed cross-linking with two-dimensional cross-linking and three-dimensional cross-linking is better. Therefore, the trifunctional isocyanate cross-linking agent and peroxide are used together. The material-based cross-linking agent or the difunctional isocyanate-based cross-linking agent is preferred. In addition, from the viewpoint of productivity and thick film coating, the active energy ray-curable adhesive composition is preferably polymerized using the aforementioned multifunctional monomer to obtain a crosslinking effect, but the above crosslinking agent or Used in combination with the aforementioned multifunctional monomer. For example, a crosslinking agent may be mixed in the mixture (monomer mixture) of the monomer components constituting the aforementioned (meth)acrylic polymer or a part of the polymer, and before and after the active energy ray of the adhesive composition is hardened, Thermal drying to complete the crosslinking agent reaction.

The amount of the crosslinking agent used is preferably 0.1 to 10 parts by weight relative to 100 parts by weight of the (meth)acrylic polymer, and preferably 0.2 to 5 parts by weight, more preferably 0.3 to 3 parts by weight. If it is within the aforementioned range, it is excellent in flex resistance and is a preferred aspect.

In addition, when the peroxide-based crosslinking agent is used alone, it is preferably 0.5 to 5 parts by weight, and more preferably 1 to 3 parts by weight with respect to 100 parts by weight of the (meth)acrylic polymer. Within the aforementioned range, it is possible to sufficiently increase the cohesive force while maintaining the easiness of deformation to a slight strain, thereby improving the durability and flex resistance, which is the preferred aspect.

In addition, when a peroxide-based crosslinking agent and an isocyanate-based crosslinking agent are used together, the weight ratio of the peroxide-based crosslinking agent to the isocyanate-based crosslinking agent (peroxide-based crosslinking agent/isocyanate-based crosslinking agent) The lower limit of is preferably 1.2 or more, preferably 1.5 or more, more preferably 3 or more. In addition, the upper limit of the weight ratio is preferably 500 or less, preferably 300 or less, and more preferably 200 or less. If it is within the aforementioned range, it is possible to sufficiently improve the cohesive force while maintaining the easiness of deformation to a slight strain, which is the preferred form.

<Other additives> In addition, the adhesive composition of the present invention may contain other well-known additives, and polyether compounds of polyalkylene glycols such as various silane coupling agents, polypropylene glycol, etc. may be appropriately added according to the application, coloring Agents, pigments and other powders, dyes, surfactants, plasticizers, tackifiers, surface lubricants, leveling agents, softeners, antioxidants, anti-aging agents, light stabilizers, ultraviolet absorbers, polymerization inhibitors , Antistatic agent (alkali metal salt of ionic compound or ionic liquid, ionic solid, etc.), inorganic or organic filler, metal powder, granular, foil, etc. In addition, a redox system to which a reducing agent is added may be used within a controllable range.

The preparation method of the aforementioned adhesive composition is not particularly limited, and a well-known method may be used. For example, as described above, the solvent-based acrylic adhesive composition is obtained by adding a (meth)acrylic polymer as needed. The components (for example, the aforementioned (meth)acrylic oligomer, crosslinking agent, silane coupling agent, solvent, additives, etc.) are mixed and produced. Also, as described above, the active energy ray-curable acrylic adhesive composition is composed of a monomer mixture or part of its polymer, and components added as needed (for example, the aforementioned photopolymerization initiator, polyfunctional monomer, the aforementioned (Meth)acrylic oligomer, crosslinking agent, silane coupling agent, solvent, additives, etc.) are mixed and produced.

The aforementioned adhesive composition preferably has a viscosity suitable for handling and application. Therefore, the active energy ray-curable acrylic adhesive composition preferably contains a part of the polymer of the monomer mixture. The polymerization rate of the aforementioned partial polymer is not particularly limited, but is preferably 5 to 20% by weight, and more preferably 5 to 15% by weight.

In addition, the polymerization rate of the aforementioned partial polymer can be obtained as follows. A part of the polymer was sampled as a sample. Accurately weigh the sample to obtain its weight, and determine it as "the weight of the polymer before drying". Next, the sample was dried at 130° C. for 2 hours, and the weight of the dried sample was accurately weighed to determine the weight, and this was determined as “the weight of the dried polymer”. Then, from the "weight of the partial polymer before drying" and "the weight of the partial polymer after drying", the weight of the sample reduced by drying at 130°C for 2 hours was obtained, and it was determined as the "weight reduction" (Volatile part, unreacted monomer weight). From the obtained "weight of partial polymer before drying" and "weight reduction amount", the polymerization rate (weight %) of the partial polymer of the monomer component was determined by the following formula. Polymerization rate of the partial polymer of the monomer component (weight %) = [1-(weight reduction)/(weight of partial polymer before drying)]×100

[Other Adhesive Layer] Among the adhesive layers used in the laminate for flexible image display devices of the present invention, the second adhesive layer may be disposed on the retardation film on the retardation film that is in contact with the polarizing film The opposite side of the surface (see Figure 2).

Among the adhesive layers used in the laminate for flexible image display devices of the present invention, the third adhesive layer may be the transparent conductive layer that constitutes the touch sensor and the transparent adhesive layer and the second adhesive layer The third adhesive layer is arranged on the opposite side of the contact surface (see FIG. 2).

Among the adhesive layers used in the laminate for flexible image display devices of the present invention, the third adhesive layer may be disposed on the transparent conductive layer and the first adhesive on the transparent conductive layer constituting the touch sensor The opposite side of the plane where the layers meet (see Figure 3).

In addition, when the second adhesive layer is used in addition to the first adhesive layer, and other adhesive layers (such as the third adhesive layer, etc.) are further used, the adhesive layers may have the same composition (same adhesive composition ). Those with the same characteristics can also be those with different characteristics. There are no special restrictions. However, from the viewpoint of workability, economy, and flexibility, all adhesive layers should be essentially those with the same composition and the same characteristics. Adhesive layer.

<Forming the adhesive layer> The method for forming the adhesive layer may be, for example, applying the solvent-based adhesive composition to a separator (peeling film) that has undergone a peeling treatment, and drying and removing the polymerization solvent to form The method of the adhesive layer; the method of coating the aforementioned solvent-based adhesive composition on the polarizing film, etc., and drying and removing the polymerization solvent, etc. to form the adhesive layer on the polarizing film; coating the active energy ray-curable adhesive composition The method is to distribute it on the separated pieces that have been peeled off and irradiate with active energy rays. In addition, if necessary, in addition to active energy ray irradiation, heating and drying may be performed. In addition, when applying the adhesive composition, one or more solvents other than the polymerization solvent may be added appropriately.

The separated parts after stripping treatment should use polysilicone stripping lining material. When the adhesive composition of the present invention is coated on the lining material and dried to form an adhesive layer, the method of drying the adhesive may be a suitable and appropriate method depending on the purpose. It is desirable to adopt a method of heating and drying the coating film. For example, the heating and drying temperature is preferably 40 to 200°C when preparing an acrylic adhesive with a (meth)acrylic polymer, and more preferably 50 to 180°C, and particularly preferably 70 to 170°C. By setting the heating temperature within the above range, an adhesive with excellent adhesive properties can be obtained.

Appropriate time can be adopted for the drying time. For example, the above drying time is preferably 5 seconds to 20 minutes when preparing an acrylic adhesive with a (meth)acrylic polymer, and more preferably 5 seconds to 10 minutes, especially 10 seconds to 5 minutes. good.

Various methods can be used for the coating method of the aforementioned adhesive composition. Specifically, for example, roll coating, contact roll coating, gravure coating, reverse coating, roll brush, spray cloth, dip roll coating, bar coating, blade coating, air blade coating, Methods such as curtain coating, lip coating, and extrusion coating using a die coater.

The thickness of the adhesive layer used in the laminate for flexible image display devices of the present invention is preferably 1 to 200 μm, and preferably 5 to 150 μm, more preferably 10 to 100 μm. The adhesive layer may be a single layer or may have a laminated structure. If it is within the aforementioned range, deflection is not hindered, and it is also preferable from the viewpoint of adhesion (resistance to hold). In addition, when there are multiple adhesive layers, all the adhesive layers are preferably within the aforementioned range.

The laminate for a flexible image display device of the present invention is preferably: the storage elastic modulus G′ of the adhesive layer at 25° C. is 1×10 ⁵ Pa or less, and represents the glass transition temperature (Tg) of the adhesive layer The peak value of tan δ (loss tangent) is 3 or less. The storage elastic modulus G′ is more preferably 8×10 ⁴ Pa or less, more preferably 6×10 ⁴ Pa or less, particularly preferably 4×10 ⁴ Pa or less, and most preferably 3×10 ⁴ Pa or less. In addition, tan δ is preferably 2.5 or less, and more preferably 2 or less, particularly preferably 1.5 or less, and most preferably 1 or less. By making the storage elastic modulus G′ of the adhesive layer at 25° C. and the peak value of tanδ representing Tg within the aforementioned range, that is, by lowering the storage elastic modulus G′, the adhesion during deflection can be made The adhesive layer is easy to strain, and by lowering tan δ, the strain stress is not easy to spread, and the adhesive layer is easy to strain, thereby allowing the laminate for flexible image display devices even under a light force (load) It can still be bent, spread out, etc., and is the better form. Moreover, we speculate that by making the strain stress difficult to diffuse, the strain stress generated during deflection can become the energy when returning from the flexed state to the flat state, and it is easy to return from the flexed state to the flat state, thereby reducing the remaining Bending angle.

In order to adjust the storage elastic modulus G′ of the adhesive layer at 25° C. to 1×10 ⁵ Pa or less, and to adjust the peak value of tanδ, which represents the glass transition temperature (Tg) of the adhesive layer, to 3 or less, use The adhesive composition for forming the adhesive layer can be exemplified as follows. When a solvent-based adhesive composition is used, the first method of the solvent-based method is to use a (meth)acrylic polymer obtained by copolymerizing the (meth)acrylic monomer having the long-chain alkyl group. In the first method of the solvent type here, it is preferable that the (meth)acrylic monomer having the long-chain alkyl group be 40% by weight or more and 99% by weight relative to the total monomer. In addition, the second method of the solvent type uses the peroxide-based crosslinking agent alone as a crosslinking agent, and adds 0.5 parts by weight or more and 5 parts by weight or less to 100 parts by weight of the (meth)acrylic polymer. The third method of the solvent type system uses a peroxide-based crosslinking agent and an isocyanate-based crosslinking agent as the crosslinking agent, and the weight ratio of the peroxide-based crosslinking agent to the isocyanate-based crosslinking agent (peroxide-based Crosslinking agent/isocyanate-based crosslinking agent) is set to 1.2 or more and 500 or less, and the addition amount of the peroxide-based crosslinking agent is set to 0.2 parts by weight or more based on 100 parts by weight of (meth)acrylic polymer. . The fourth method of the solvent type is the second method or the third method of the solvent type, and the (meth)acrylic oligomer 1 is further added as described above with respect to 100 parts by weight of the (meth)acrylic polymer. More than 70 parts by weight. On the other hand, when using an active energy ray-curable adhesive composition, the first method of the active energy ray-curable type uses the (meth)acrylic monomer having the long-chain alkyl group as the main component and contains A mixture (monomer mixture) of a monomer having an alkyl group or a functional group having a carbon number of 1 or more and 5 or a part of the polymer of the mixture is polymerized together with a polyfunctional monomer. In addition, the second method of the active energy ray hardening type uses the first method of the active energy ray hardening type as the (meth)acrylic monomer having the long-chain alkyl group, having a carbon number of 10 or more and 30 A mixture (monomer mixture) of a (meth)acrylic monomer of the following alkyl group and a (meth)acrylic monomer having an alkyl group of 6 or more and 9 or less, or a partial polymer of the mixture. In the first method and the second method of the active energy ray hardening type here, it is preferable to set the content of the (meth)acrylic monomer having a long-chain alkyl group to 60% by weight or more in the total monomer. It is more preferably 70% by weight or more. On the other hand, it is preferably 100% by weight or less, and more preferably 99% by weight or less. In addition, when using a mixture of a (meth)acrylic monomer having an alkyl group of 10 or more and 30 or less and a (meth)acrylic monomer having an alkyl group of 6 or more and 9 or less, the mixing ratio Preferably, ((meth)acrylic monomer having an alkyl group of 10 or more and 30 or less carbon): ((meth)acrylic monomer having an alkyl group of 6 or more and 9 or less) = 40 : 60~90: 10.

In the laminate for a flexible image display device of the present invention, the loss elastic modulus G'' of the adhesive layer at 25°C is preferably 1×10 ⁵ Pa or less, and preferably 8×10 ⁴ Pa or less, 4× Below 10 ⁴ Pa is better. By making the loss elastic modulus G'' of the adhesive layer at 25°C within the aforementioned range, that is, by lowering the loss elastic modulus G'', the adhesive layer cannot be easily integrated into the flexure state, thereby It can reduce the remaining bending angle when recovering flat, and it is the best form.

The upper limit of the glass transition temperature (Tg) of the adhesive layer used in the laminate for flexible image display devices of the present invention is preferably 5° C. or lower. If the flexibility in a low-temperature environment or a high-speed region is taken into consideration, it is better to be below -20°C and even better than -25°C. As long as the Tg of the adhesive layer is within the above range, even if it is flexed in a low-temperature environment or a high-speed region where the bending speed exceeds 1 second/time, the adhesive layer is not likely to harden, and the stress relaxation is excellent Thus, it is possible to realize a laminate body for a flexible image display device that is flexible or foldable, and a flexible image display device in which the laminate body for the flexible image display device is disposed.

The total light transmittance (in accordance with JIS　K7136) of the adhesive layer used in the laminate for flexible image display devices of the present invention in the visible wavelength region is preferably 85% or more, and more preferably 90% or more.

[Transparent conductive layer] The member having a transparent conductive layer is not particularly limited, and known ones can be used, but examples include those having a transparent conductive layer on a transparent substrate such as a transparent film, or a member having a transparent conductive layer and a liquid crystal cell .

The transparent base material only needs to be transparent, and for example, a base material composed of a resin film or the like (for example, a sheet-shaped or film-shaped, plate-shaped base material, etc.), etc. The thickness of the transparent substrate is not particularly limited, and it is preferably about 10 to 200 μm, and more preferably about 15 to 150 μm.

The material of the aforementioned resin film is not particularly limited, and various plastic materials having transparency can be cited. Examples of the material include polyester resins such as polyethylene terephthalate and polyethylene naphthalate, acetate resins, polyether resins, polycarbonate resins, and polyamide resins. Polyimide resin, polyolefin resin, (meth)acrylic resin, polyvinyl chloride resin, polydivinylidene resin, polystyrene resin, polyvinyl alcohol resin, polyarylate resin Resin, polyphenylene sulfide resin, etc. Among these, polyester-based resins, polyimide-based resins, and polyether-based resins are particularly preferred.

In addition, etching treatment or primer treatment such as sputtering, corona discharge, flame, ultraviolet irradiation, electron beam irradiation, chemical conversion, oxidation, etc. may be performed on the surface of the transparent substrate in advance to enhance the transparent conductive layer provided thereon Adhesion to the aforementioned transparent substrate. In addition, before the transparent conductive layer is provided, dust or cleaning may be performed by solvent washing or ultrasonic washing if necessary.

The constituent material of the transparent conductive layer is not particularly limited, and can be selected from the group consisting of indium, tin, zinc, gallium, antimony, titanium, silicon, zirconium, magnesium, aluminum, gold, silver, copper, palladium, tungsten, and molybdenum. At least one metal or metal oxide in the group, or an organic conductive polymer such as polythiophene. The metal oxide may further contain the metal atoms shown in the above group as required. For example, indium oxide (ITO) containing tin oxide, tin oxide containing antimony, etc., and ITO is particularly suitable. ITO preferably contains 80 to 99% by weight of indium oxide and 1 to 20% by weight of tin oxide.

In addition, the aforementioned ITO includes crystalline ITO and amorphous (amorphous) ITO. Crystalline ITO can be produced by applying a high temperature during sputtering or further heating amorphous ITO.

The thickness of the transparent conductive layer of the present invention is preferably 0.005-10 μm, and preferably 0.01-3 μm, more preferably 0.01-1 μm. If the thickness of the transparent conductive layer does not reach 0.005 μm, the resistance value of the transparent conductive layer will tend to increase. On the other hand, if it is greater than 10 μm, the productivity of the transparent conductive layer will decrease, the cost will also increase, and the optical characteristics will also tend to decrease.

The total light transmittance of the transparent conductive layer of the present invention is preferably 80% or more, and preferably 85% or more, and more preferably 90% or more.

The density of the transparent conductive layer of the present invention is preferably 1.0 to 10.5 g/cm ³ , and preferably 1.3 to 3.0 g/cm ³ .

The surface resistance of the transparent conductive layer of the present invention is preferably 0.1 to 1000 Ω/□, and preferably 0.5 to 500 Ω/□, more preferably 1 to 250 Ω/□.

The method for forming the transparent conductive layer is not particularly limited, and a conventionally known method can be used. Specifically, examples include a vacuum evaporation method, a sputtering method, and an ion plating method. Also, an appropriate method can be adopted according to the required film thickness.

In addition, an undercoat layer, an anti-oligomer layer, etc. can be provided between the transparent conductive layer and the transparent substrate according to requirements.

The aforementioned transparent conductive layer is required to constitute a touch sensor and be configured to be bendable.

The laminate for a flexible image display device of the present invention can arrange the transparent conductive layer constituting the touch sensor to the second adhesive layer on the surface of the second adhesive layer that is in contact with the retardation film The opposite side (refer to FIG. 2).

The laminate for a flexible image display device of the present invention may dispose the transparent conductive layer constituting the touch sensor to the first adhesive layer on the opposite side of the surface of the first adhesive layer that is in contact with the protective film Side (see Figure 3).

Furthermore, in the laminate for a flexible image display device of the present invention, the transparent conductive layer constituting the touch sensor may be disposed between the protective film and the window film (OCA) (see FIG. 3).

When the aforementioned transparent conductive layer is used in a flexible image display device, it can be well applied to a built-in type or a top-mounted type liquid crystal display device in which a touch sensor is embedded, in particular, the touch sensor can also be embedded in (Incorporated in) organic EL display panel.

[Conductive layer (antistatic layer)] Furthermore, the laminate for flexible image display devices of the present invention may also have a layer having conductivity (conductive layer, antistatic layer). Since the laminate for flexible image display devices has a flexing function and is very thin in structure, it has a high reactivity to weak static electricity generated in manufacturing steps and the like, and is susceptible to damage. However, due to the laminate The provision of the conductive layer can greatly reduce the load caused by static electricity in the manufacturing process and the like, and is the preferred aspect.

In addition, one of the major features of the flexible image display device including the aforementioned laminate is its flexure function. However, after continuous deflection, static electricity may be generated due to shrinkage between the films (substrate) of the flexure. . Therefore, if the electrical conductivity of the laminate is given, the generated static electricity can be quickly removed, and the damage caused by the static electricity to the image display device can be reduced, which is the preferred aspect.

In addition, the conductive layer may be an undercoat layer having a conductive function, may also be an adhesive containing a conductive component, and may also be a surface treatment layer containing a conductive component. For example, the following method may be used: an antistatic agent composition containing a conductive polymer such as polythiophene and an adhesive is used to form a conductive layer between the polarizing film and the adhesive layer. Also, an adhesive containing an ionic compound that is an antistatic agent, etc. may be used. In addition, the conductive layer preferably has one or more layers, or may contain two or more layers.

The laminated body for a flexible image display device of the present invention is characterized by an optical film including an adhesive layer and at least a polarizing film, and after bending the laminated body by 180° and then returning it to a flattened shape, the remaining bending The angle is 0°~60°, and the aforementioned bending angle is preferably 0°~50°, and 0°~40° is better, 0°~30° is even better, 0°~25° is especially good, 0°~ 20° is the best. That is, the closer the bending angle is to 0°, the more ideal it is. By bending the layered body 180° and then flattening it, the remaining bending angle is within the aforementioned range, a layered body for a flexible image display device can be produced even if it is repeatedly bent, Each layer between the adhesive layer and the layer will not peel off or break, so it has excellent flex resistance and adhesion, and is the preferred form.

The overall thickness of the laminate for a flexible image display device of the present invention is preferably 1000 μm or less, preferably 800 μm or less, and more preferably 500 μm or less. In addition, the overall thickness is preferably 20 μm or more, preferably 100 μm or more. If the thickness of the entire thickness is greater than 1000 μm, the difference between the strain applied to the outermost layer and the innermost layer of the flexure will increase, and cracking or peeling will easily occur during flexure. Moreover, if the overall thickness is made to exceed 1000 μm, the strain of the adhesive layer will also increase, and it will be easily plastically deformed, resulting in the remaining bending angle when it is to be restored from the flexed state to flat It will become larger, which is not ideal.

[Flexible image display device] The flexible image display device of the present invention includes the above-described laminate for a flexible image display device and an organic EL display panel, and a laminate for a flexible image display device is arranged on the viewing side of the organic EL display panel Body, and is configured to be bendable. Although it is an optional option, a window can be arranged on the viewing side of the laminate for flexible image display devices (refer to FIGS. 2 to 4).

2 is a cross-sectional view showing an embodiment of the flexible image display device of the present invention. The flexible image display device 100 includes a laminate 11 for a flexible image display device and an organic EL display panel 10 that can be bent. In addition, the organic EL display panel 10 is provided with a laminate 11 for a flexible image display device on the viewing side, and the flexible image display device 100 is configured to be bendable. In addition, although it is an arbitrary option, a transparent window 40 can be disposed on the viewing side of the laminate 11 for a flexible image display device via the first adhesive layer 12-1.

The laminate 11 for a flexible image display device includes an optical laminate 20, and further includes an adhesive layer that constitutes the second adhesive layer 12-2 and the third adhesive layer 12-3.

The optical laminate 20 includes a polarizing film 1, a protective film 2 of a transparent resin material, and a retardation film 3. The protective film 2 of transparent resin material is bonded to the first surface on the viewing side of the polarizing film 1. The retardation film 3 is bonded to the second surface of the polarizing film 1 that is different from the first surface. The polarizing film 1 and the retardation film 3 are, for example, films for generating circularly polarized light or compensating the viewing angle in order to prevent internal light from the viewing side of the polarizing film 1 from being internally reflected and then exiting to the viewing side.

In this embodiment, unlike the conventional protective film provided on both sides of the polarizing film, the protective film is provided only on one side, and compared with the polarizing film used in the conventional organic EL display device, the polarizing film itself A polarizing film with a very thin thickness (20 μm or less) is also used, so the thickness of the optical laminate 20 can be reduced. Furthermore, since the polarizing film 1 is very thin compared to the polarizing film used in the conventional organic EL display device, the stress due to expansion and contraction due to temperature or humidity conditions becomes extremely small. Therefore, the stress caused by the shrinkage of the polarizing film greatly reduces the possibility of deformation of the adjacent organic EL display panel 10 such as warpage, and the reduction of the display quality due to the deformation and the destruction of the panel sealing material can be greatly suppressed. In addition, by using a thin polarizing film, it does not hinder the deflection and is the preferred aspect.

To bend or restore the optical layered body 20 to the inner side of the protective film 2, by thinning the thickness of the optical layered body 20 (for example, 92 μm or less), the first adhesive layer 12-1 as described above By arranging the protective film 2 on the opposite side of the protective film 2 from the retardation film 3, the bending angle remaining in the optical layered body 20 can be reduced, thereby the optical layered body 20 can be bent and the deflection can be suppressed The cracking of each layer in the curved portion and the peeling of the adhesive layer can finally make the laminate 11 for the flexible image display device bendable. Moreover, it is also possible to set an appropriate range of remaining bending angles according to the ambient temperature of the flexible image display device.

Although it is an arbitrary option, the retardation film 3 may be further provided with a bendable transparent conductive layer 6 constituting a touch sensor on the side of the retardation film 3 opposite to the protective film 2. For example, the transparent conductive layer 6 can be made into a structure directly bonded to the retardation film 3 according to the manufacturing method shown in Japanese Patent Laid-Open No. 2014-219667, thereby reducing the thickness of the optical layered body 20, which can be further reduced The stress applied to the optical laminate 20 when the optical laminate 20 is bent.

Although it is an optional option, the transparent conductive layer 6 may be further provided with an adhesive layer constituting the third adhesive layer 12-3 on the side of the transparent conductive layer 6 opposite to the retardation film 3. In this embodiment, the second adhesive layer 12-2 is directly bonded to the transparent conductive layer 6. By providing the second adhesive layer 12-2, the stress applied to the optical laminate 20 when bending the optical laminate 20 can be further reduced.

The flexible image display device shown in FIG. 3 is almost the same as that shown in FIG. 2 except for the following points: In the flexible image display device of FIG. 2, the retardation film 3 is placed on the retardation film 3. On the side opposite to the protective film 2 is a flexible transparent conductive layer 6 constituting a touch sensor. In contrast, in the flexible image display device of FIG. 3, the first adhesive layer 12-1 is attached to On the side opposite to the protective film 2 of the first adhesive layer 12-1, a transparent conductive layer 6 that can be folded to constitute a touch sensor is disposed. Furthermore, the following points are different: In the flexible image display device of FIG. 2, the third adhesive layer 12-3 is disposed on the opposite side of the transparent conductive layer 2 from the retardation film 3 to the transparent conductive layer 2, On the other hand, in the flexible image display device of FIG. 3, the second adhesive layer 12-2 is disposed on the phase difference film 3 on the side of the phase difference film 3 opposite to the protective film 2.

In addition, although it is an optional option, when the window 40 is disposed on the viewing side of the laminate 11 for a flexible image display device, the third adhesive layer 12-3 may be disposed.

The flexible image display device of the present invention can be suitably used as an image display device such as a flexible liquid crystal display device, an organic EL (electroluminescence) display device, and electronic paper. In addition, it can be used regardless of the touch panel method such as the resistive film method and the capacitive method.

In addition, the flexible image display device of the present invention can also be used as a built-in flexible image display device in which the transparent conductive layer 6 constituting the touch sensor is embedded in the organic EL display panel 10-1 as shown in FIG. 4. Examples

Various embodiments related to the present invention will be described below, but those shown in these specific examples are not intended to limit the present invention. In addition, the numerical value in the table is a blending amount (addition amount), and shows a solid content or a solid content ratio (weight basis). The blending contents and evaluation results are listed in Table 1 to Table 5.

[Example 1] [Polarizing film] An amorphous polyethylene terephthalate (hereinafter also referred to as "PET") (IPA copolymerized PET) film (thickness: 100 μm) having 7 mol% isophthalic acid units was prepared As a thermoplastic resin base material, corona treatment (58W/m ² /min) was applied to the surface. On the other hand, a modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) with the addition of 1% by weight of acetoacetate is prepared, and the trade name: GOHSEFIMER Z200 (average degree of polymerization: 1200, degree of saponification: 98.5 mol%, ethyl Acetyl acetylation degree: 5 mol%) PVA (degree of polymerization 4200, saponification degree 99.2%), and prepare a coating solution of PVA aqueous solution of 5.5% by weight of PVA resin, so that the film thickness after drying becomes After coating at 12 μm and drying with hot air in a gas environment at 60° C. for 10 minutes, a laminate having a PVA-based resin layer on the substrate was produced.

Then, the laminate was first extended 1.8 times in air at 130°C (free end extension in air) to produce an extended laminate. Next, the PVA layer is subjected to an insolubilization step, that is, the stretch laminate is immersed in a boric acid insoluble aqueous solution at a liquid temperature of 30°C for 30 seconds to orient the PVA molecules contained in the stretch laminate. The boric acid insoluble aqueous solution in this step is to make the boric acid content 3 parts by weight relative to 100 parts by weight of water. Then, the extended laminate is dyed to produce a colored laminate. The coloring layering system immerses the extended layered body in a dyeing solution containing iodine and potassium iodide at a liquid temperature of 30°C for any time in such a way that the monomer transmittance of the PVA layer constituting the polarizing film finally formed becomes 40 to 44%. In this case, iodine is used to dye the PVA layer contained in the extended laminate. In this step, the dyeing solution uses water as the solvent, and the iodine concentration is set in the range of 0.1 to 0.4% by weight, and the potassium iodide concentration is set in the range of 0.7 to 2.8% by weight. The concentration ratio of iodine to potassium iodide is 1 to 7. Next, a step of cross-linking the PVA molecules of the PVA layer is performed, that is, the colored laminate is immersed in a 30°C boric acid cross-linking aqueous solution for 60 seconds to adsorb iodine. In this step, the boric acid cross-linking aqueous solution is such that the boric acid content is 3 parts by weight with respect to 100 parts by weight of water, and the potassium iodide content is 3 parts by weight with respect to 100 parts by weight of water.

Then, the obtained colored laminate was extended in an aqueous boric acid solution at an extension temperature of 70° C. in the same direction as the previous extension in the air by 3.05 times (borate extension in water), and an optical film with a final extension ratio of 5.50 times was prepared Layered body. The optical film laminate was removed from the boric acid aqueous solution, and the boric acid adhering to the surface of the PVA layer was washed with an aqueous solution having a potassium iodide content of 4 parts by weight relative to 100 parts by weight of water. The cleaned optical film laminate is dried in a drying step using warm air at 60°C. The thickness of the polarizing film contained in the obtained optical thin-film laminate was 5 μm.

[Protective Film] The protective film is obtained by extruding a methacrylic resin pellet having a glutarimide ring unit into a film shape and then extending it. The protective film is an acrylic film with a thickness of 20 μm and a moisture permeability of 160 g/m ² .

Next, the polarizing film and the protective film were bonded using an adhesive shown below to form a polarizing film.

The aforementioned adhesive (active energy ray-curable adhesive) was prepared by mixing the ingredients according to the blending table described in Table 1, and stirred at 50°C for 1 hour to prepare an adhesive (active energy ray-curable adhesive A) . The numerical value in the table shows the weight% when the total amount of the composition is set to 100% by weight. The ingredients used are as follows. HEAA: hydroxyethyl acrylamide M-220: ARONIX M-220, tripropylene glycol diacrylate), manufactured by East Asia Synthetic Corporation ACMO: N-propylene acetylmorpholine AAEM: 2-ethyl acetyl ethyl oxyethyl Methacrylate, UP-1190 manufactured by Nippon Synthetic Chemical Corporation: ARUFON UP-1190, IRG907 manufactured by East Asia Synthetic Corporation: IRGACURE907, 2-methyl-1-(4-methylthiophenyl)-2-morpholin -1-one, DETX-S manufactured by BASF: KAYACURE DETX-S, diethyl 9-oxysulfur , Manufactured by Nippon Kayaku

[Table 1]

In addition, in Examples and Comparative Examples using the adhesive, the protective film and the polarizing film are laminated through the adhesive, and then the ultraviolet ray is irradiated to harden the adhesive to form an adhesive layer. For ultraviolet irradiation, a metal halide lamp filled with gallium (made by Fusion UV Systems, Inc., trade name "Light HAMMER10", bulb: V bulb, peak illuminance: 1600mW/cm ² , cumulative exposure 1000/mJ/cm ² ( (Wavelength 380~440nm).

[Retardation film] The retardation film (1/4 wavelength retardation plate) of this embodiment is a retardation layer for quarter wave plate and a retardation layer for 1/2 wave plate which are oriented and fixed by a liquid crystal material The retardation film composed of these two layers. Specifically, it is manufactured according to the following procedure.

(Liquid crystal material) The material used to form the retardation layer for the half-wavelength plate and the retardation layer for the 1/4-wavelength plate is a polymer liquid crystal material (made by BASF: trade name Paliocolor LC242) with a nematic liquid crystal phase ). A photopolymerization initiator (made by BASF: trade name Irgacure 907) used in the polymerizable liquid crystal material was dissolved in toluene. In order to improve the coating property, the MEGAFACE series made by DIC is prepared with a liquid crystal coating liquid by adding about 0.1 to 0.5% according to the thickness of the liquid crystal. After the liquid crystal coating liquid was applied on the alignment substrate by a bar coater, it was heated and dried at 90° C. for 2 minutes, and then cured by ultraviolet ray under a nitrogen atmosphere to fix the alignment. For the base material, for example, a material that can be transferred to the liquid crystal coating layer afterwards like PET is generally used. In addition, in order to improve the coating property, the MEGAFACE series fluoropolymer made by DIC is added to about 0.1% to 0.5% according to the thickness of the liquid crystal layer, and MIBK (methyl isobutyl ketone), cyclohexanone, or MIBK and ring are used The mixed solvent of hexanone was dissolved to a solid content concentration of 25% to prepare a coating liquid. This coating liquid was applied to the base material with a wire rod, and after a drying step was performed at 65° C. for 3 minutes, it was cured by ultraviolet curing under a nitrogen atmosphere to fix the orientation. For the base material, for example, a material that can be transferred to the liquid crystal coating layer afterwards like PET is generally used.

(Manufacturing process) The manufacturing process of this embodiment will be described with reference to FIG. 7. In addition, the numbers in FIG. 7 are different from the numbers in other drawings. In this manufacturing step 20, the base material 14 is supplied with rollers, and the base material 14 is supplied from the supply reel 21. In the manufacturing step 20, the coating liquid of the ultraviolet curable resin 10 is coated on the substrate 14 by the die head 22. In this manufacturing step 20, the roll plate 30 is a cylindrical mold for forming, and the concave-convex shape of the alignment film for a quarter-wave plate with a quarter-wave retardation plate is formed on the peripheral side surface. In the manufacturing step 20, the substrate 14 coated with the ultraviolet curable resin is pressed onto the peripheral side surface of the roll plate 30 by the pressure roller 24, and ultraviolet irradiation is performed by an ultraviolet irradiation device 25 composed of a high-pressure mercury lamp to make the ultraviolet curable The resin hardens. In this way, in the manufacturing step 20, the uneven shape formed on the peripheral side surface of the roll plate 30 is transferred to the base material 14 at 75° in the MD direction. After that, the base material 14 and the cured ultraviolet curable resin 10 are peeled off from the roll plate 30 in an integrated state by the peeling roller 26, and the liquid crystal material is coated with the die 29. After that, the ultraviolet ray irradiation device 27 is used to irradiate the ultraviolet ray to harden the liquid crystal material, and the phase difference layer for the quarter-wave plate is formed by these procedures. Next, in this step 20, the substrate 14 is conveyed to the die 32 by the conveying roller 31, and the ultraviolet curable resin 12 is applied to the 1/4 wavelength plate retardation layer of the substrate 14 by the die 32 Cloth liquid. In this manufacturing step 20, the roll plate 40 is a cylindrical mold for forming, and the concave-convex shape of the alignment film for a half-wavelength plate with a quarter-wavelength retardation plate is formed on the peripheral side surface. In the manufacturing step 20, the substrate 14 coated with the ultraviolet curable resin is pressed onto the peripheral side surface of the roll plate 40 by the pressure roller 34, and ultraviolet irradiation is performed by an ultraviolet irradiation device 35 composed of a high-pressure mercury lamp to make the ultraviolet curable The resin hardens. With this, in the manufacturing step 20, the uneven shape formed on the peripheral side surface of the roll plate 40 is transferred to the base material 14 at 15° in the MD direction. After that, the base material 14 and the cured ultraviolet curable resin 12 are peeled off from the roll plate 40 in an integrated state by the peeling roller 36, and the liquid crystal material is coated with the die 39. After that, the ultraviolet ray irradiation device 37 is used to irradiate the ultraviolet ray to harden the liquid crystal material, and the phase difference layer for the half-wavelength plate is made by these procedures, thereby producing the phase difference layer for the quarter-wavelength plate, A retardation film with a thickness of 7 μm composed of two layers of a retardation layer for 1/2 wavelength plate.

[Optical film (optical laminate)] The phase difference film produced by the above procedure and the polarizing film produced by the above procedure are continuously bonded by a roll-to-roll method using the above-mentioned adhesive, and A laminated film (optical laminate) was produced by making the axis angle of the slow axis and the absorption axis 45°.

[Second Adhesive Layer] <Preparation of (meth)acrylic polymer A1> A four-necked flask equipped with a stirring blade, thermometer, nitrogen introduction tube, and cooler was fed with 99 parts by weight of butyl acrylate (BA), acrylic acid 4-hydroxybutyl (HBA) 1 part by weight of monomer mixture. And with respect to 100 parts by weight of the aforementioned monomer mixture (solid content), 0.12 parts by weight of 2,2'-azobisisobutyronitrile (AIBN) as a polymerization initiator was fed together with ethyl acetate while slowly stirring After introducing nitrogen for nitrogen replacement, the temperature of the liquid in the flask was kept at around 55°C for 7 hours for polymerization reaction. After that, ethyl acetate was added to the resulting reaction liquid to prepare a solution of (meth)acrylic polymer A1 whose solid content was adjusted to a concentration of 30% and a weight average molecular weight of 1.6 million.

<Preparation of acrylic adhesive composition (P1)> The isocyanate-based crosslinking agent (trade name: TAKENATE D110N, III) is blended with respect to 100 parts by weight of the solid content of the prepared (meth)acrylic polymer A1 solution. Hypromethane diisocyanate stubble ester, Mitsui Chemicals Co., Ltd. 0.1 parts by weight, peroxide-based crosslinking agent benzoyl peroxide (trade name: NYPER BMT, Japan Oils and Fats Co., Ltd.) 0.3 By weight, 0.3 parts by weight of a silane coupling agent (trade name: A-100, manufactured by Kken Chemical Co., Ltd.) containing acetyl acetyl groups, and an acrylic adhesive composition (P1) was prepared.

<Preparation of an optical laminate with an adhesive layer> The acrylic adhesive composition (P1) was uniformly applied to a polyphenylene terephthalate with a thickness of 75 μm treated with a silicone release agent using a spray coater The surface of the ethylene formate film (separator) was dried in an air circulation constant temperature oven at 155°C for 2 minutes to form a second adhesive layer with a thickness of 70 μm on the surface of the substrate. Next, the separation member formed with the second adhesive layer is transferred to the protective film side of the optical laminate thus prepared (corona-treated) to produce an optical laminate with an adhesive layer.

[First Adhesive Layer] After forming the first adhesive layer with a thickness of 50 μm in the same manner as the second adhesive layer described above, the first adhesive layer is blended according to Table 2 and Table 3 to form The separator with the first adhesive layer is transferred to the surface of the polyimide film (PI film, DU PONT-TORAY (share), Kapton 300V, substrate) with a thickness of 75 μm (corona treated), and Manufacture PI film with adhesive layer.

[Third Adhesive Layer] After forming the third adhesive layer with a thickness of 50 μm in the same manner as the second adhesive layer described above, the third adhesive layer is formed according to the blending contents in Table 2 and Table 3 The separator with the third adhesive layer was transferred to the surface of the PET film (transparent substrate, made by Mitsubishi Resin Co., Ltd., trade name: DIAFOIL) with a thickness of 125 μm (corona-treated) to produce an adhesive. PET film.

<Layered body for flexible image display device> As shown in FIG. 6, the first to third adhesive layers (along with each transparent substrate) prepared by the above procedure at a thickness of 25 μm are used as the transparent substrate 8 The PET film of -1 is attached to the first adhesive layer 12-1, and the third adhesive layer 12-3 is attached to the retardation film 3, and the transparent substrate to which the first adhesive layer 12-1 is attached On the surface of 8-1 (PET film) where the transparent conductive layer 6 is formed, the second adhesive layer 12-2 is bonded to thereby produce a laminate 11 for a flexible image display device used in the examples.

<Preparation of acrylic oligomer (oligomer B1) and acrylic adhesive composition (P2)> A four-necked flask equipped with a stirring blade, thermometer, nitrogen introduction tube, and cooler was fed with butyl acrylate (BA) 95 Parts by weight, 2 parts by weight of acrylic acid (AA), 3 parts by weight of methyl acrylate (MA), 0.1 parts by weight of 2,2'-azobisisobutyronitrile as polymerization initiator and 140 parts by weight of toluene, while slowly After introducing nitrogen gas while stirring to sufficiently perform nitrogen substitution, the liquid temperature in the flask was maintained at around 70° C. for 8 hours to carry out a polymerization reaction to prepare an acrylic oligomer (oligomer B1) solution. The weight average molecular weight of the oligomer B1 is 4500. The obtained oligomer B1 was prepared by adding a predetermined amount when mixing a crosslinking agent, etc., to prepare an acrylic adhesive composition (P2).

[Example 2 and Comparative Examples 1 to 2] When preparing the used polymer ((meth)acrylic polymer) and acrylic oligomer, adhesive composition and adhesive layer, unless otherwise specified Except for the above, it was changed to those shown in Tables 2 to 4, except that in the same manner as in Example 1, a laminate for a flexible image display device was produced.

[Examples 3 to 6] 100 parts by weight of the monomer mixture shown in Table 2 and 2,2-dimethoxy-1,2-diphenylethyl-1-one (trade name) of the photopolymerization initiator "IRGACURE 651", manufactured by BASF Japan Co., Ltd.) and 1-hydroxy-cyclohexyl-phenyl-ketone (trade name "IRGACURE 184", manufactured by BASF Japan Co., Ltd.) each 0.05 parts by weight were put into a four-necked flask, and Irradiate ultraviolet rays under a nitrogen atmosphere until its viscosity (BH viscometer No. 5 rotor, 10 rpm, temperature 30°C) reaches about 15 Pa·s, and perform photopolymerization to prepare a partially polymerized monomer slurry (part of the monomer component) Polymer) A2~A5. In 100 parts by weight of each prepared polymerized monomer slurry, 1,6-hexanediol diacrylate (trade name "A-HD-N", Shin Nakamura Chemical Co., Ltd. Co., Ltd., HDDA, polyfunctional monomer 0.3 parts by weight, and 2,2-dimethoxy-1,2-diphenylethyl-1-one (trade name "IRGACURE 651", manufactured by BASF Japan Co., Ltd. , Photopolymerization initiator (additional initiator)) 0.6 parts by weight and silane coupling agent (trade name "KBM-403", Shin-Etsu Chemical Industry Co., Ltd.) 0.3 parts by weight to obtain an acrylic adhesive composition (P3)~(P6). Apply the above acrylic adhesive composition to the peeled surface of the release film (trade name "MRF#38", manufactured by Mitsubishi Resin Co., Ltd.) so that the thickness of the adhesive layer after formation is 70 μm. To form an adhesive composition layer, and then, a peeling film (trade name "MRN #38", manufactured by Mitsubishi Resin Co., Ltd.) is attached to the surface of the adhesive composition layer. Thereafter, ultraviolet light was irradiated under the conditions of illuminance: 4 mW/cm ² and light quantity: 1200 mJ/cm ^{2 to} photoharden the adhesive composition layer to form an adhesive layer. Then, a second adhesive layer protected by a release film on both sides of the adhesive layer was prepared. Next, one of the peeling films used to protect the second adhesive layer is peeled off, and the peeling film on which the second adhesive layer is formed is transferred to the protective film side of the obtained optical laminate (corona has been passed) Process) to produce an optical laminate with an adhesive layer. Next, the first adhesive layer and the third adhesive layer were produced in the same manner as the second adhesive layer described above, and the laminate system for flexible image display devices was produced in the same manner as in Example 1.

In addition, all the layers including the adhesive layer used in the examples and the comparative examples used the same thickness as that of the example 1.

The abbreviations in Table 2 and Table 3 are as follows. BA: n-butyl acrylate 2EHA: 2-ethylhexyl acrylate AA: HBA acrylate: 4-hydroxybutyl acrylate HEA: 2-hydroxyethyl acrylate iOA: isooctyl acrylate iNA: isononyl acrylate LA: lauryl acrylate Ester MA: methyl acrylate D110N: trimethylolpropane/diisocyanate extended ester adduct (Mitsui Chemicals, trade name: TAKENATE D110N) C/L: trimethylolpropane/toluene diisocyanate ( Japan Polyurethane Industry Co., Ltd., trade name: CORONATE L) A-HD-N: 1,6-hexanediol diacrylate (manufactured by Shin Nakamura Chemical Co., Ltd., trade name: A-HD-N) Peroxide: Benzoyl peroxide (manufactured by Nippon Oil & Fats Co., Ltd., trade name: NYPER BMT) IRGACURE184: photopolymerization initiator, 1-hydroxy-cyclohexyl-phenyl-ketone (manufactured by BASF) IRGACURE651: photopolymerization initiator, 2,2-Dimethoxy-1,2-diphenylethyl-1-one (manufactured by BASF) AIBN: Azo polymerization initiator, 2,2´-azobisisobutyronitrile (KISHIDA Chemical ( Stock)

[Evaluation] <Measurement of the weight average molecular weight (Mw) of (meth)acrylic polymer and acrylic oligomer> The weight average molecular weight of the prepared (meth)acrylic polymer and acrylic oligomer ( Mw) is measured by GPC (gel permeation chromatography).・Analysis device: Tosoh (Tosoh) Co., Ltd., HLC-8120GPC ・Column: Tosoh Co., Ltd., G7000H _XL +GMH _XL +GMH _XL・Column size: each 7.8mmφ×30cm Count 90cm ・Column temperature: 40℃・Flow rate: 0.8ml/min ・Injection volume: 100μl ・Eluent: Tetrahydrofuran ・Detector: Differential refractometer (RI) ・Standard sample: Polystyrene

<Measure the storage elastic modulus G'and loss elastic modulus G'' of the adhesive layer and calculate tan δ> Separate the separator from the adhesive layer of each example and comparative example, and laminate multiple adhesive layers to produce Test sample with a thickness of about 2mm. The test sample was punched with a disc-shaped hole with a diameter of 7.9 mm, sandwiched between parallel plates, and then "Advanced Rheometric Expansion System (ARES)" manufactured by Rheometric Scientific was used to perform dynamic viscoelasticity measurement under the following conditions, and from the measurement results Read the storage elastic modulus G'and loss elastic modulus G'' of the adhesive layer at 25°C. In addition, the tan δ (loss tangent) of the adhesive layer of the glass transition temperature (Tg) is calculated by the following formula. tanδ (loss tangent) = G”/G’ (measurement conditions) Deformation mode: torsion Measurement temperature: -70℃~150℃ Heating rate: 5℃/min

<Measured Thickness> The thickness of the polarizing film, retardation film, protective film, optical laminate, adhesive layer, etc. is measured using a dial gauge (manufactured by Mitutoyo).

<Folding resistance (continuous deflection) test method> FIGS. 5(A) and (B) are schematic diagrams showing a flexure test performed by a U-shaped telescopic test machine (YUASA SYSTEM MACHINE CO., LTD.). The aforementioned testing machine is a mechanism capable of repeatedly bending a planar body workpiece with a U-shape under a no-load state in a constant temperature bath by 180°, which can be changed by adjusting the distance between the surfaces bent into a U-shape radius. In the test, the 2.5 cm×10 cm laminate for flexible image display devices prepared in each example and comparative example was installed in a testing machine so as to be bendable in the longitudinal direction, and at 25° C.×50%RH , The evaluation is carried out under the conditions of a bending angle of 180°, a bending radius of 3 mm, and a bending speed of 1 second/time. In addition, the sample for measurement (evaluation) is configured as shown in FIG. 6 with the transparent substrate 8-2 (PET film) as the concave side (inside) and the substrate 9 (PI film) as the convex side ( Outer), after bending in the long side near the center, evaluate. The flexural strength was evaluated by the number of times until the flexure of the laminate for a flexible image display device was cracked or peeled between layers. Here, the test was terminated when the number of bendings reached 200,000. <Are there any peelings and cracks> ◎: 200,000 times or more without defects (practical problem-free) ○: 100,000 to less than 200,000 times without defects (practical problem-free) △: 50,000 to less than 100,000 Times and defective (no problem in practical use) ×: less than 50,000 times and defective (practical problem)

<Bending angle> After bending for 180 hours from the initial flat state (bending angle 0°) in the above flexure test and holding it for 24 hours, return to the initial position (flat) and the sample is flexible The image display device was removed with the laminate, and then placed at room temperature (25°C) for 5 minutes with no external load applied in the bending direction of the sample, and the remaining bending angle of the sample was evaluated.

[Table 2]

[table 3]

[Table 4] Note) The thickness of each case is the same thickness (first adhesive layer: 50 μm, second adhesive layer: 70 μm, third adhesive layer: 50 μm).

[table 5]

From the evaluation results of Table 4 and Table 5, it can be confirmed that in all the examples, the bending angle is controlled within the desired range, and after the flexural resistance (continuous deflection) test, the fracture (breaking) or The peeling is also practically problem-free. That is, it can be confirmed that in the laminate for flexible image display devices of the embodiments, by using the laminate for flexible image display devices having a bending angle in a desired range, a flexible image display can be produced The laminated body for a device has no rupture (breaking) or peeling in the face of repeated deflection, and thus has excellent flex resistance and adhesion.

On the other hand, it can be confirmed that the bending angles of Comparative Examples 1 and 2 are beyond the desired range, and the flexural resistance (continuous deflection) test is practically problematic in terms of breaking (breaking) or peeling. Degree, and the resistance to deflection or adhesion is poor. In particular, in Comparative Example 1, since the bending angle greatly exceeded the desired range, it was confirmed that it had peeling and cracking, and it was confirmed that its flex resistance and adhesion were very poor.

1‧‧‧ Polarizing film

2. 2-1, 2-2 ‧‧‧ protective film

3‧‧‧ phase difference layer

4-1, 4-2‧‧‧‧Transparent conductive film

5-1, 5-2‧‧‧ substrate film

6, 6-1, 6-2‧‧‧‧Transparent conductive layer

7‧‧‧Partition

8‧‧‧Transparent substrate

8-1, 8-2‧‧‧Transparent substrate (PET film)

9‧‧‧ Base material (PI film)

10‧‧‧ organic EL display panel

10‧‧‧ (Figure 7) UV curable resin

10-1‧‧‧ organic EL display panel (with touch sensor)

11‧‧‧Layer for flexible image display device (Layer for organic EL display device)

12‧‧‧Adhesive layer

12‧‧‧ (Figure 7) UV curable resin

12-1‧‧‧1st adhesive layer

12-2‧‧‧The second adhesive layer

12-3‧‧‧The third adhesive layer

13‧‧‧Decorative printing film

14‧‧‧ Double-sided adhesive tape

14‧‧‧ (Figure 7)

20‧‧‧Optical laminate

20‧‧‧ (Figure 7) manufacturing steps

21‧‧‧ (Figure 7) Supply reel

22, 29, 32, 39 ‧‧‧ (Figure 7)

24, 34‧‧‧ (Figure 7) Pressure roller

25, 27, 35, 37 ‧‧‧ (Figure 7) ultraviolet irradiation device

26, 36‧‧‧ (Figure 7) Peeling roller

30‧‧‧Touch panel

30、40‧‧‧(Picture 7) Roll version

31‧‧‧(Figure 7) Conveying roller

40‧‧‧window

100‧‧‧Flexible image display device (organic EL display device)

P‧‧‧Deflection point

UV‧‧‧UV irradiation

L‧‧‧Liquid crystal material

FIG. 1 is a cross-sectional view showing a conventional organic EL display device. 2 is a cross-sectional view showing a flexible image display device according to an embodiment of the present invention. 3 is a cross-sectional view showing a flexible image display device according to another embodiment of the present invention. 4 is a cross-sectional view showing a flexible image display device according to another embodiment of the present invention. Fig. 5 is a diagram showing a flexure test ((A) bending angle 0°, (B) bending angle 180°). 6 is a cross-sectional view showing samples for evaluation used in Examples. FIG. 7 is a diagram showing a method of manufacturing the phase difference used in the examples.

Claims (7)

A laminated body for a flexible image display device, comprising: an optical film including an adhesive layer and at least a polarizing film, and the remaining bending angle after bending the laminated body by 180° and then returning it to flattening is 0°~60°. The laminate for a flexible image display device according to claim 1, wherein the storage elastic modulus G′ of the adhesive layer at 25° C. is 1×10 ⁵ Pa or less, and represents the glass transition temperature (Tg) of the adhesive layer ) Has a peak value of tan δ of 3 or less. The laminate for flexible image display devices according to claim 1 or 2, wherein the loss elastic modulus G'' of the adhesive layer at 25°C is 1×10 ⁵ Pa or less. The laminate for flexible image display devices according to any one of claims 1 to 3, which has the aforementioned adhesive layer of 2 or more and 5 or less. The laminate for a flexible image display device according to any one of claims 1 to 4, wherein the adhesive layer is formed of an adhesive composition containing a (meth)acrylic polymer. A flexible image display device, comprising: the laminate for a flexible image display device according to any one of claims 1 to 5, and an organic EL display panel, and the organic EL display panel is disposed on a viewing side The laminate for a flexible image display device. According to the flexible image display device of claim 6, a window is arranged on the viewing side of the laminate for the flexible image display device.