TW202035126A - Laminate, adhesive composition, and adhesive sheet - Google Patents

Abstract

The purpose of the present invention is to provide a laminate having excellent heat resistance and flexibility at low temperatures. The present invention provides a laminate including a front plate, a first adhesive layer, a polarizer layer, a second adhesive layer, and a back plate in this order. Both the first adhesive layer and the second adhesive layer exhibit a tan[delta] from 1.5 to 2.0 at a temperature of -40 DEG C and are formed from an adhesive composition including a (meth)acrylic polymer. The (meth)acrylic polymer contains, on the basis of the total polymer mass, less than 5 mass% of a structural unit derived from a monomer having a reactive functional group.

Description

Laminated body, adhesive composition and adhesive sheet

The invention relates to a laminate, an adhesive composition and an adhesive sheet.

It is known that an adhesive film having an adhesive layer containing an adhesive composition is used in a display device (Patent Document 1 to Patent Document 3). [Prior Art Literature] [Patent Literature]

[Patent Document 1] Korean Patent No. 10-2014-0085299 Specification [Patent Document 2] Korean Patent No. 10-2016-0053736 Specification [Patent Document 3] Japanese Patent Laid-Open No. 2018-27995 Specification

[The problem to be solved by the invention] When the laminate used in a display device is bent at a low temperature, cracks may occur in the adhesive layer. In addition, at low temperatures, the adhesive force of the adhesive layer decreases, which may cause floating or peeling between the adhesive layer and the adhered member.

The object of the present invention is to provide a laminate having excellent flexibility at low temperature and adhesive strength at low temperature, an adhesive composition and adhesive sheet used in the laminate. [Means to solve the problem]

The present invention provides the following laminates, adhesive compositions and adhesive sheets. [1] A laminated body, including in order: a front surface plate, a first adhesive layer, a polarizer layer, a second adhesive layer and a back plate, The first adhesive layer and the second adhesive layer both have a tanδ of 1.5 or more and 2.0 or less at a temperature of -40°C, and are formed of an adhesive composition containing a (meth)acrylic polymer, In the (meth)acrylic polymer, the structural unit derived from a monomer having a reactive functional group is less than 5% by mass based on the total mass of the polymer. [2] The laminate according to [1], wherein the front surface plate is a film in which a hard coat layer is provided on at least one surface of a base film. [3] The laminate according to [1] or [2], wherein the weight average molecular weight (Mw) of the (meth)acrylic polymer is 200,000 or more and 1.5 million or less. [4] The laminate according to any one of [1] to [3], wherein the adhesive composition further contains a monofunctional (meth)acrylic monomer having an alkoxy group. [5] The laminate according to any one of [1] to [4], wherein the back panel is a touch sensor panel. [6] A display device including the laminate according to any one of [1] to [5]. [7] An adhesive composition comprising: a (meth)acrylic polymer and a monofunctional (meth)acrylic monomer having an alkoxy group, and In the (meth)acrylic polymer, the structural unit derived from a monomer having a reactive functional group is less than 5% by mass based on the total mass of the polymer. [8] An adhesive sheet comprising an adhesive layer formed of the adhesive composition as described in [7]. [Effects of the invention]

According to the present invention, it is possible to provide a laminate having excellent flexibility at low temperature and adhesive force at low temperature, an adhesive composition and an adhesive sheet used in the laminate.

Hereinafter, a laminate according to an embodiment of the present invention (hereinafter also simply referred to as "laminate") will be described with reference to the drawings.

＜Laminated body＞ Fig. 1 shows a schematic cross-sectional view of a laminate according to an embodiment of the present invention. The laminate 100 includes a front surface plate 101, a first adhesive layer 102, a polarizer layer 103, a second adhesive layer 104 and a back plate 105 in sequence. Hereinafter, the first adhesive layer 102 and the second adhesive layer 104 are sometimes collectively referred to as an adhesive layer.

The thickness of the layered body 100 varies depending on the functions required for the layered body and the purpose of the layered body, and is therefore not particularly limited. For example, it is 50 μm or more and 4,000 μm or less, preferably 100 μm or more and 2000 μm or less, and more It is preferably 150 μm or more and 1000 μm or less.

The planar shape of the laminate 100 may be, for example, a square shape, preferably a square shape having long sides and short sides, and more preferably a rectangular shape. When the shape of the laminate 100 in the plane direction is a rectangle, the length of the long side may be, for example, 10 mm or more and 1400 mm or less, and preferably 50 mm or more and 600 mm or less. The length of the short side is, for example, 5 mm or more and 800 mm or less, preferably 30 mm or more and 500 mm or less, and more preferably 50 mm or more and 300 mm or less. Each layer constituting the layered body may be R processed at the corners, cut at the ends, or drilled.

The laminated body 100 can be used, for example, in a display device or the like. The display device is not particularly limited, and examples thereof include organic electroluminescence (organic electroluminescence, organic EL) display devices, inorganic electroluminescence (inorganic EL) display devices, liquid crystal display devices, electroluminescence display devices, and the like. The display device may have a touch panel function.

[Tanδ of adhesive layer] In the laminated body 100, the tan δ at the temperature of the first adhesive layer 102 and the second adhesive layer 104 at −40° C. are both 1.5 or more and 2.0 or less. As a result, the laminate 100 tends to be excellent in flexibility at low temperatures. From the viewpoint of suppressing cracks, the temperature of the first adhesive layer 102 and the second adhesive layer 104 in the laminate 100 is preferably 1.6 or more and 1.9 or less in tan δ at a temperature of -40°C. The tanδ at a temperature of -40°C can be measured in accordance with the measurement method described in the column of Examples described later.

In a laminate used in a display device, one of the properties required for the adhesive layer is stress relaxation properties. However, even if it is an adhesive layer with excellent stress relaxation properties, cracks may occur in the adhesive layer due to bending at low temperature. As a result of research conducted by the present inventors, it was found that when the tanδ at a temperature of -40°C is within the above range, the stress relaxation characteristics tend to be easily sustained even at low temperatures. As a result, even when repeated bending at low temperatures , The adhesive layer and the constituent members of the laminate are maintained, and cracks in the adhesive layer can be suppressed.

The so-called excellent flexibility at low temperatures means that at least one direction in the plane of the laminate 100 can be bent so that the inner surface of the laminate 100 has a bending radius of 3.0 mm at a temperature of -20°C, so that no cracks can occur. To bend. In the laminated body 100, when at least one direction in its plane is repeatedly bent so that the inner surface of the laminated body 100 has a bending radius of 3.0 mm at a temperature of -20°C, it is preferable that the number of bending is 10,000 times No cracks will occur. In the present invention, cracks in the adhesive layer include cracks generated in the adhesive layer, peeling between the adhesive layer and constituent members of the laminate, and the like. In this specification, bending includes a bending form in which a curved surface is formed in a curved portion. In the bent form, the bending radius of the bent inner surface is not particularly limited. In addition, bending includes a bending form in which the bending angle of the inner surface is greater than 0 degrees and less than 180 degrees, and a folding form in which the bending radius of the inner surface is approximately zero or the bending angle of the inner surface is 0 degrees.

In the laminate 100, the tanδ of the first adhesive layer and the second adhesive layer at -40°C are both 1.5 or more and 2.0 or less, so the front surface plate side can be bent on the inside (infold) It can also be achieved by bending (outfold) on the front side of the front surface plate.

Since the tanδ of the first adhesive layer 102 and the second adhesive layer 104 at a temperature of -40°C is both 1.5 or more and 2.0 or less, the layered body 100 has a temperature of -20°C in at least one direction within its plane. When repeatedly bending the inner surface of the laminated body 100 with a bending radius of 3.0 mm, it is preferable that no cracks occur even if the number of bendings is 10,000. When the laminated body 100 is repeatedly bent with a bending radius of 3.0 mm on the inner surface of the laminated body 100 at a temperature of -20°C in at least one direction in its plane, it is more preferable even if the number of bendings is 20,000 times No cracks are generated, and it is more preferable that no cracks occur even if the number of bendings is 50,000 times, and it is more preferable that no cracks occur even if the number of bendings is 100,000 times. It is preferable that the laminated body 100 is at least about one in-plane direction and a direction orthogonal thereto, and the number of times of bending without cracking when the repeated bending is performed at a temperature of -40° C. is within the above range. The display device to which the laminate 100 is applied can be used as a flexible display that can be bent, wound, etc.

As a method of making the tanδ of the first adhesive layer 102 and the second adhesive layer 104 at a temperature of -40°C of 1.5 or more and 2.0 or less, for example, an adhesive layer may be formed from an adhesive composition A described later, or Change the type of monomers constituting the (meth)acrylic polymer A described later, or adjust the molecular weight of the (meth)acrylic polymer A, or make the adhesive composition A contain monofunctionality having an alkoxy group (Meth)acrylic monomer, or a method of adjusting the type of crosslinking agent or the content of each component in the adhesive composition A, a method of combining these methods, and the like.

[Adhesive composition] From the viewpoint of crack suppression, both the first adhesive layer 102 and the second adhesive layer 104 are formed of an adhesive composition containing a (meth)acrylic polymer (hereinafter also referred to as an adhesive composition A). The adhesive composition A may be an active energy ray hardening type or a heat hardening type. In addition, the "(meth)acrylic polymer" in this specification means at least one selected from the group consisting of acrylic polymer and methacrylic polymer. The same applies to other terms with "(methyl)". Hereinafter, the (meth)acrylic polymer contained in the adhesive composition A is also referred to as (meth)acrylic polymer A.

(1) Active energy ray hardening adhesive composition When the adhesive composition A is an active energy ray-curable adhesive composition, the (meth)acrylic polymer A is derived from a monomer having a reactive functional group based on the total mass of the polymer The constituent units are less than 5 mass%. Examples of the reactive functional group include a hydroxyl group, a carboxyl group, an amino group, an amide group, and an epoxy group. This improves the flexibility of the adhesive layer, and tends to easily suppress cracks in the adhesive layer at low temperatures. From the viewpoint of suppressing cracks, the (meth)acrylic polymer A is preferably based on the total mass of the polymer, and the constituent unit derived from a monomer having a reactive functional group is 1% by mass or less, more preferably It is 0.01 mass% or less, and it is more preferable that it does not have the structural unit derived from the monomer which has a reactive functional group, and it is still more preferable that it does not have a hydroxyl group, a carboxyl group, an amino group, an amido group, and an epoxy group.

The (meth)acrylic polymer A may include the following structural unit derived from a (meth)acrylic monomer having a linear or branched alkyl group having 1 to 24 carbon atoms . As the (meth)acrylic monomer having a linear or branched alkyl group having 1 to 24 carbon atoms, for example, alkyl (meth)acrylate, etc., and examples thereof include : Butyl (meth)acrylate, methyl (meth)acrylate, ethyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, lauryl (meth)acrylate, ( Isooctyl meth)acrylate, isodecyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isobornyl (meth)acrylate, and the like. The (meth)acrylic polymer A may be a polymer or copolymer containing one or two or more of the alkyl (meth)acrylate as a monomer. Based on the total mass% of the solid content of the adhesive composition A, the content of the (meth)acrylic polymer A in the adhesive composition A may be, for example, 50% by mass or more and 100% by mass or less, and is preferably 80% by mass or more and 99.5% by mass or less, more preferably 90% by mass or more and 99% by mass or less.

The weight average molecular weight (Mw) of the (meth)acrylic polymer A can be, for example, 200,000 or more and 1.5 million or less, and can be 300,000 or more and 700,000 or less. From the viewpoint of improving the flexibility, it is preferably 300,000 or more and 600,000 or less. The weight average molecular weight (Mw) can be measured in accordance with the measurement method described in the column of Examples described later.

The adhesive composition A may contain one or two or more (meth)acrylic polymers A. In addition, the adhesive composition A may contain only the (meth)acrylic polymer A as its constituent component, or may further contain a crosslinking agent. Examples of the crosslinking agent include: a metal ion having a valence of two or more and forming a metal carboxylic acid salt with a carboxyl group; a polyamine compound forming an amide bond with a carboxyl group; a polyepoxy compound or Polyols and those that form ester bonds with carboxyl groups; those that are polyisocyanate compounds and those that form amide bonds with carboxyl groups. Among them, the crosslinking agent is preferably a polyisocyanate compound. When the adhesive composition A contains a crosslinking agent, the content of the crosslinking agent may be, for example, 5 parts by mass or less, preferably 1 part by mass or less, relative to 100 parts by mass of the (meth)acrylic polymer A , More preferably 0.5 parts by mass or less, and still more preferably 0.1 parts by mass or less. The adhesive composition A preferably does not contain a crosslinking agent.

The so-called active energy ray curable adhesive composition means that it has the property of being cured by irradiation of active energy rays such as ultraviolet rays or electron rays, and has adhesiveness even before the active energy rays are irradiated, so that it can bond with the film. Adhesive composition that can adjust the properties of adhesion and other properties such as the adhesion of the adherend and hardening by irradiation of active energy rays.

The active energy ray curable adhesive composition is preferably an ultraviolet curable adhesive composition.

In addition to the (meth)acrylic polymer A, from the viewpoint of improving the flexibility, the adhesive composition A preferably contains a monofunctional (meth)acrylic monomer having an alkoxy group. Examples of alkoxy groups include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, second butoxy, and tertiary butoxy. Examples of monofunctional (meth)acrylic monomers having alkoxy groups include EOEOEA and nonylphenol ethylene oxide (EO) modification Acrylate [NP(EO)8A] etc. Based on the total mass of the solid content of the adhesive composition A, the content of the monofunctional (meth)acrylic monomer having an alkoxy group in the adhesive composition A may be, for example, 3% by mass or more and 10% by mass %the following. By containing a monofunctional (meth)acrylic monomer having an alkoxy group, the form of the polymer chain tends to become a flexible linear structure.

When the adhesive composition A is an active energy ray curable adhesive composition, the adhesive composition A may further contain an active energy ray polymerizable compound, a photopolymerization initiator, or a photosensitizer.

As the active energy ray polymerizable compound, for example, a (meth)acrylate monomer having at least one (meth)acryloyloxy group in the molecule; obtained by reacting two or more functional group-containing compounds, and (Meth)acrylic compounds such as (meth)acryloxy group-containing compounds such as (meth)acrylate oligomers having at least two (meth)acryloxy groups. Based on the total mass of the solid content of the adhesive composition A, the adhesive composition A may contain 3% by mass or more and 10% by mass or less of the active energy ray polymerizable compound.

Examples of the photopolymerization initiator include benzil dimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, and the like. When the adhesive composition A contains a photopolymerization initiator, it may contain one kind or two or more kinds. When the adhesive composition A contains a photopolymerization initiator, the total content thereof may be 0.01% by mass or more and 1.0% by mass or less based on the total mass of the solid content of the adhesive composition A, for example.

The adhesive composition A may contain fine particles, beads (resin beads, glass beads, etc.), glass fibers, resins other than raw polymers, adhesiveness imparting agents, fillers (metal powder or other inorganic powders) for imparting light scattering properties Etc.), antioxidants, ultraviolet absorbers, dyes, pigments, colorants, defoamers, anti-corrosion agents, photopolymerization initiators and other additives. From the viewpoint of preventing the problem of durability reduction caused by the residual solvent, the adhesive composition A preferably does not contain an organic solvent.

When the adhesive layer is formed of the adhesive composition A, the adhesive layer can be formed by coating the adhesive composition A on the substrate. In the case of using an active energy ray-curable adhesive composition, the formed adhesive layer can be irradiated with active energy rays to produce a cured product having a desired degree of curing.

(2) Thermosetting adhesive composition When the adhesive composition A is a thermosetting adhesive composition, the (meth)acrylic polymer A is preferably an alkyl (meth)acrylate having 2 to 20 carbon atoms, And a monomer having a reactive functional group in the molecule (a monomer containing a reactive functional group) is used as a monomer unit constituting the polymer.

The (meth)acrylic polymer A has an alkyl (meth)acrylic acid alkyl ester having 2 to 20 carbon atoms as a monomer unit constituting the polymer, and can exhibit better adhesiveness. The alkyl (meth)acrylate having a carbon number of 2-20 as the alkyl group is preferably a homopolymer having a glass transition temperature (Tg) of -40°C or less (hereinafter sometimes referred to as "low Tg acrylic acid Alkyl ester"). By containing the low Tg alkyl acrylate as a constituent monomer unit, the flexibility of the adhesive layer is improved, and it is easy to prevent cracks in the adhesive layer at low temperature, floating or peeling of the adhesive layer at low temperature, and generation at low temperature. The tendency of bubbles.

As the low Tg alkyl acrylate, for example, n-butyl acrylate (Tg is -55°C), n-octyl acrylate (Tg is -65°C), and isooctyl acrylate (Tg is -58°C) , 2-ethylhexyl acrylate (Tg is -70℃), isononyl acrylate (Tg is -58℃), isodecyl acrylate (Tg is -60℃), isodecyl methacrylate (Tg is- 41℃), n-lauryl methacrylate (Tg is -65℃), tridecyl acrylate (Tg is -55℃), tridecyl methacrylate (-40℃), etc. Among them, from the viewpoint that the tanδ at -40°C of the resulting adhesive easily enters the range, as the low Tg alkyl acrylate, the homopolymer has a Tg of -45°C or less, and particularly preferably Those below -50℃. Specifically, n-butyl acrylate and 2-ethylhexyl acrylate are particularly preferred. These can be used alone or in combination of two or more.

In the (meth)acrylic polymer A, as the monomer unit constituting the polymer, the following limit is preferably 85% by mass or more of low Tg alkyl acrylate, more preferably 90% by mass or more, and further It is preferable to contain 95% by mass or more. If it is such a range, the tanδ at a temperature of -40°C easily enters the range.

In addition, in the (meth)acrylic polymer A, as a monomer unit constituting the polymer, it is preferable that the above limit contains the low Tg alkyl acrylate in an amount of 99.9% by mass or less, and more preferably 99.5 mass% % Or less, more preferably 99% by mass or less. By containing 99.9% by mass or less of the low Tg alkyl acrylate, an appropriate amount of other monomer components (especially monomers containing reactive functional groups) can be introduced into the (meth)acrylic polymer A.

In order to easily set the glass transition temperature (Tg) of the main polymer of the adhesive of the present embodiment within the above range, the (meth)acrylic polymer A is preferably as low as possible as the homopolymer glass transition temperature ( Tg) The content of monomers exceeding 0°C (hereinafter sometimes referred to as "hard monomers"). Specifically, in the (meth)acrylic polymer A, as a monomer unit constituting the polymer, the content of the hard monomer is preferably set to 15% by mass or less, more preferably 10 Mass% or less, more preferably 5 mass% or less. In addition, the hard monomer also includes the reactive functional group-containing monomer described later.

As the hard monomer, for example, methyl acrylate (Tg is 10°C), methyl methacrylate (Tg is 105°C), ethyl methacrylate (Tg is 65°C), n-butyl methacrylate Esters (Tg is 20°C), isobutyl methacrylate (Tg is 48°C), tertiary butyl methacrylate (Tg is 107°C), n-stearyl acrylate (Tg is 30°C), methacrylic acid Stearyl ester (Tg is 38°C), cyclohexyl acrylate (Tg is 15°C), cyclohexyl methacrylate (Tg is 66°C), phenoxyethyl acrylate (Tg is 5°C), methyl Phenoxyethyl acrylate (Tg is 54°C), benzyl methacrylate (Tg is 54°C), isobornyl acrylate (Tg is 94°C), isobornyl methacrylate (Tg is 180°C), acrylic Acrylic morpholine (Tg of 145°C), adamantyl acrylate (Tg of 115°C), adamantyl methacrylate (Tg of 141°C), acrylic acid (Tg of 103°C), dimethyl acrylate Acrylic monomers such as amine (Tg: 89°C), acrylamide (Tg: 165°C), vinyl acetate (Tg: 32°C), styrene (Tg: 80°C), etc.

The (meth)acrylic polymer A contains a reactive functional group-containing monomer as a monomer unit constituting the polymer, and passes through the reactive functional group derived from the reactive functional group-containing monomer to be described later The thermal crosslinking agent reacts to form a crosslinked structure (three-dimensional network structure) to obtain an adhesive with the desired cohesive force.

Examples of the reactive functional group-containing monomer contained in the (meth)acrylic polymer A as a monomer unit constituting the polymer include: monomers having a hydroxyl group in the molecule (a hydroxyl group-containing monomer Monomers), monomers having carboxyl groups in the molecule (carboxyl group-containing monomers), monomers having amine groups in the molecule (amine group-containing monomers), etc. Among these, in many cases where the glass transition temperature (Tg) is 0°C or less, a hydroxyl group-containing monomer is particularly preferred.

Examples of hydroxyl-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 2 (meth)acrylic acid. -Hydroxyalkyl (meth)acrylates such as hydroxybutyl, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, etc. Among them, in terms of the glass transition temperature (Tg), the reactivity of the hydroxyl group in the obtained (meth)acrylic polymer A with the thermal crosslinking agent, and the copolymerizability with other monomers, it is preferably At least one of 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 3-hydroxypropyl acrylate, and 4-hydroxybutyl acrylate. These can be used alone or in combination of two or more.

Examples of carboxyl group-containing monomers include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. These can be used alone or in combination of two or more.

Examples of the amine group-containing monomer include aminoethyl (meth)acrylate and n-butylaminoethyl (meth)acrylate. These can be used alone or in combination of two or more.

In the (meth)acrylic polymer A, the structural unit derived from a monomer having a reactive functional group is less than 5% by mass based on the total mass of the polymer. In the (meth)acrylic polymer A, the lower limit of the structural unit derived from the monomer having a reactive functional group is preferably 0.1% by mass or more, particularly preferably 0.5% by mass or more, and more preferably 1% by mass the above. In addition, the upper limit is preferably 4% by mass or less, particularly preferably 3.5% by mass or less, and still more preferably 3% by mass or less. If the (meth)acrylic polymer A contains a reactive functional group-containing monomer, especially a hydroxyl-containing monomer, as a monomer unit in the stated amount, the resulting adhesive has a tanδ at a temperature of -40°C. Enter the range.

The (meth)acrylic polymer A may not contain a carboxyl group-containing monomer, particularly acrylic acid which is also a hard monomer, as a monomer unit constituting the polymer. The carboxyl group is an acid component. Therefore, by not containing a carboxyl group-containing monomer, even if there is a problem caused by acid in the object of the adhesive, such as tin-doped indium oxide (indium tin oxide, ITO )) etc. In the case of transparent conductive films, metal films, metal meshes, etc., these disadvantages (corrosion, resistance value changes, etc.) due to acid can also be suppressed.

The (meth)acrylic polymer A may also contain other monomers as monomer units constituting the polymer as necessary. As other monomers, in order not to interfere with the function of the reactive functional group-containing monomer, it is also preferable that the monomer does not contain a reactive functional group. As the other monomers, for example, in addition to alkoxyalkyl (meth)acrylates such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate, homopolymers may be mentioned. A monomer whose glass transition temperature (Tg) exceeds -40°C and is below 0°C (hereinafter sometimes referred to as "medium Tg alkyl acrylate" and the like. As medium Tg alkyl acrylate, for example, ethyl acrylate (Tg -20°C), isobutyl acrylate (Tg is -26°C), 2-ethylhexyl methacrylate (Tg is -10°C), n-lauryl acrylate (Tg is -23°C), iso-hard acrylic acid Fatty ester (Tg is -18°C), etc. These can be used alone or in combination of two or more.

The polymerization state of (meth)acrylic polymer A may be a random copolymer or a block copolymer.

The lower limit of the weight average molecular weight of the (meth)acrylic polymer A is preferably 200,000 or more, particularly preferably 300,000 or more, and still more preferably 400,000 or more. If the lower limit of the weight average molecular weight of the (meth)acrylic polymer A is more than the above, it is possible to suppress defects such as leaching of the adhesive. In addition, the weight average molecular weight in this specification is a value in terms of standard polystyrene measured by a gel permeation chromatography (GPC) method.

In addition, the upper limit of the weight average molecular weight of the (meth)acrylic polymer A is preferably 1.5 million or less, particularly preferably 1.35 million or less, and still more preferably 1.2 million or less. If the upper limit value of the weight average molecular weight of the (meth)acrylate polymer (A) is the above-mentioned or less, the tan δ at the temperature of -40°C of the obtained adhesive will easily fall into the above-mentioned range.

In addition, in the adhesive composition A, the (meth)acrylic polymer A may be used alone or in combination of two or more.

When the adhesive composition A containing the thermal crosslinking agent is heated, the thermal crosslinking agent crosslinks the (meth)acrylic polymer A to form a three-dimensional network structure. Thereby, the cohesive force of the obtained adhesive is improved, and the tanδ at the temperature of -40°C of the adhesive easily enters the range.

The thermal crosslinking agent may be one that reacts with the reactive group possessed by the (meth)acrylic polymer A, and examples thereof include isocyanate crosslinking agents, epoxy crosslinking agents, and amine crosslinking agents. Linking agent, melamine-based cross-linking agent, aziridine-based cross-linking agent, hydrazine-based cross-linking agent, aldehyde-based cross-linking agent, oxazoline-based cross-linking agent, metal alkoxide-based cross-linking agent, metal chelate Crosslinking agent, metal salt crosslinking agent, ammonium salt crosslinking agent, etc. Among the above, when the reactive group possessed by the (meth)acrylic polymer A is a hydroxyl group, it is preferable to use an isocyanate-based crosslinking agent having excellent reactivity with the hydroxyl group. Furthermore, the thermal crosslinking agent may be used alone or in combination of two or more.

The isocyanate-based crosslinking agent contains at least a polyisocyanate compound. Examples of polyisocyanate compounds include aromatic polyisocyanates such as toluene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate; isophorone diisocyanate, Hydrogenated diphenylmethane diisocyanate and other alicyclic polyisocyanates, etc.; and these biuret bodies, isocyanurate bodies, and as a combination with ethylene glycol, propylene glycol, neopentyl glycol, and trimethylolpropane , Castor oil and other adducts of the reaction products of compounds containing low molecular active hydrogen. Among them, from the viewpoint of reactivity with hydroxyl groups, aromatic polyisocyanates modified with trimethylolpropane are preferred, and toluene diisocyanate modified with trimethylolpropane and trimethylolpropane modified are particularly preferred. Xylylene diisocyanate.

As an epoxy-based crosslinking agent, for example, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl- M-xylylenediamine, ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidyl aniline, diglycidyl amine, etc.

Relative to 100% by mass of the (meth)acrylic polymer A, the content of the thermal crosslinking agent in the adhesive composition A is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and still more preferably 0.1% by mass %the above. In addition, the content is preferably 1% by mass or less, more preferably 0.8% by mass or less, and still more preferably 0.5% by mass or less. When the content of the thermal crosslinking agent is in the range, the tanδ at the temperature of -40°C of the resulting adhesive easily enters the range.

The adhesive composition A preferably contains the silane coupling agent. Thereby, the adhesiveness of the obtained adhesive agent layer and each member in the flexible laminated body which is an adherend improves, and the durability to bending becomes more excellent.

The silane coupling agent is preferably an organosilicon compound having at least one alkoxysilyl group in the molecule, and has good compatibility with the (meth)acrylic polymer A, and has light transmittance.

Examples of the silane coupling agent include: vinyl trimethoxy silane, vinyl triethoxy silane, methacryloxypropyl trimethoxy silane, and other polymerizable unsaturated group-containing silicon compounds; 3-condensation Silicon compounds with epoxy structure such as glyceroxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, etc.; 3-mercaptopropyltrimethoxysilane, 3-mercapto Sulfhydryl-containing silicon compounds such as propyltriethoxysilane, 3-mercaptopropyldimethoxymethylsilane, etc.; 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3 -Aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane and other amino-containing silicon compounds; 3-chloropropyltrimethoxy Silane, 3-isocyanate propyltriethoxysilane, or at least one of these and methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane, etc. Condensates of alkyl-containing silicon compounds, etc. These can be used alone or in combination of two or more.

Relative to 100% by mass of the (meth)acrylic polymer A, the content of the silane coupling agent in the adhesive composition A is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and still more preferably 0.1% by mass the above. In addition, the content is preferably 1% by mass or less, more preferably 0.5% by mass or less, and still more preferably 0.3% by mass or less. When the content of the silane coupling agent is in the above range, the resulting adhesive layer has better adhesion to each member in the flexible laminate as an adherend.

In the adhesive composition A, the various additives described above can be added as necessary. In addition, the polymerization solvent or the dilution solvent is regarded as not being included in the additives constituting the adhesive composition A.

The (meth)acrylic polymer A can be produced by polymerizing a mixture of monomers constituting the polymer by a normal radical polymerization method. The polymerization of the (meth)acrylic polymer A is preferably carried out by a solution polymerization method using a polymerization initiator as necessary. As a polymerization solvent, ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone, etc. are mentioned, for example, You may use 2 or more types together.

Examples of the polymerization initiator include azo compounds, organic peroxides, and the like, and two or more of them may be used in combination. As the azo compound, for example, 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane 1-carbonitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxypentane) Nitrile), dimethyl 2,2'-azobis(2-methylpropionate), 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis( 2-hydroxymethylpropionitrile), 2,2'-azobis[2-(2-imidazolin-2-yl)propane] and the like.

Examples of organic peroxides include: benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, peroxy Di(2-ethoxyethyl) oxydicarbonate, t-butyl peroxyneodecanoate, t-butyl peroxyvalerate, peroxide (3,5,5-trimethylhexyl) , Dipropylene peroxide, diacetyl peroxide, etc.

Furthermore, in the polymerization step, the weight average molecular weight of the obtained polymer can be adjusted by formulating a chain transfer agent such as 2-mercaptoethanol.

After obtaining the (meth)acrylic polymer A, add a thermal crosslinking agent, a silane coupling agent, and additives and diluent solvents as necessary to the solution of the (meth)acrylic polymer A, and mix them thoroughly, thereby The adhesive composition A (coating solution) diluted with a solvent is obtained.

In addition, in any of the above-mentioned components, when a solid one is used, or when precipitation occurs when mixed with other components in an undiluted state, the component may be separately dissolved in advance Or diluted in dilute solvent, and then mixed with other ingredients.

As the diluent solvent, for example, aliphatic hydrocarbons such as hexane, heptane, and cyclohexane; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as dichloromethane and dichloroethane; methanol, ethanol, and propylene Alcohol, butanol, 1-methoxy-2-propanol and other alcohols; acetone, methyl ethyl ketone, 2-pentanone, isophorone, cyclohexanone and other ketones; ethyl acetate, butyl acetate, etc. Esters; Ethyl siloxu and other siloxus-based solvents.

The concentration and viscosity of the coating solution prepared in this way are not particularly limited as long as they are in a range that can be coated, and can be appropriately selected according to the situation. For example, dilution is performed so that the concentration of the adhesive composition A is 10% by mass to 60% by mass. In addition, when obtaining a coating solution, the addition of a dilution solvent etc. is not an essential condition, and if the adhesive composition A has the viscosity etc. which can apply|coat, the dilution solvent may not be added. In this case, the adhesive composition A becomes a coating solution in which the polymerization solvent of the (meth)acrylic polymer A is directly used as a diluting solvent.

The adhesive agent preferable as the adhesive agent of this embodiment is what crosslinked the adhesive agent composition A. The crosslinking of the adhesive composition A can be performed by heat treatment. In addition, this heat treatment can also be used as a drying treatment at the time of volatilizing the coating film of the adhesive composition A obtained by applying a dilution solvent or the like to a desired object.

The heating temperature of the heat treatment is preferably 50°C to 150°C, more preferably 70°C to 120°C. In addition, the heating time is preferably 10 seconds to 10 minutes, more preferably 50 seconds to 2 minutes.

After the heat treatment, if necessary, a curing period of about 1 to 2 weeks may be set at normal temperature (for example, 23° C., 50% RH). In the case where the curing period is required, the adhesive is formed after the curing period has passed, and in the case where the curing period is not required, the adhesive is formed after the heat treatment is completed.

Through the heat treatment (and curing), the (meth)acrylic polymer A is sufficiently crosslinked via a crosslinking agent to form a crosslinked structure, and an adhesive is obtained. The tanδ at -40°C of the adhesive easily enters the range.

The adhesive sheet of the present invention includes an adhesive layer formed of the adhesive composition A of the present invention. The adhesive layer can be formed by coating the adhesive composition A on the substrate. In the case of using a thermosetting adhesive composition as the adhesive composition A, the formed adhesive layer can be heated (and cured) to produce a cured product having a desired degree of curing. In addition, the heat treatment and curing conditions are as described above.

The substrate may be a release film that has been subjected to mold release treatment. The adhesive sheet can be produced by pre-forming a layer containing an adhesive on the release film into a sheet shape, and then attaching another release film on the adhesive layer.

As a method of applying the coating liquid of the adhesive composition A, for example, a bar coating method, a knife coating method, a roll coating method, a knife coating method, a die coating method, a gravure coating method, etc. can be used.

[Front Panel] As long as the front surface plate 101 is a plate-shaped body capable of transmitting light, the material and thickness are not limited, and may include only one layer, or two or more layers. As an example, a resin plate-shaped body (for example, a resin plate, a resin sheet, a resin film, etc.), a glass plate-shaped body (for example, a glass plate, a glass film, etc.), and the touch sensor panel mentioned later can be mentioned. The front surface plate may be the most surface of the display device.

The thickness of the front surface plate 101 may be, for example, 10 μm or more and 500 μm or less, preferably 20 μm or more and 200 μm or less, and more preferably 30 μm or more and 100 μm or less. In the present invention, the thickness of each layer can be measured in accordance with the thickness measurement method described in the below-mentioned Examples.

In the case where the front surface plate 101 is a plate-shaped body made of resin, the plate-shaped body made of resin is not limited as long as it can transmit light. Examples of the resin constituting the plate-shaped body made of resin such as resin film include triacetyl cellulose, acetyl cellulose butyrate, ethylene-vinyl acetate copolymer, acryl-based cellulose, butyl-based cellulose, Acetyl propylene cellulose, polyester, polystyrene, polyamide, polyetherimide, poly(meth)acrylic acid, polyimide, polyether chrysene, poly chrysene, polyethylene, polypropylene , Polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyether ketone, polyether ether ketone, polyether ash, polymethyl methacrylate, polyterephthalate Films formed of polymers such as ethylene formate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, and polyamide imide. These polymers can be used alone or in combination of two or more. From the viewpoint of improving strength and transparency, a resin film formed of a polymer such as polyimide, polyimide, and polyimide is preferred. The thickness of the resin plate-shaped body may be, for example, 10 μm or more and 500 μm or less, preferably 20 μm or more and 200 μm or less, more preferably 30 μm or more and 150 μm or less, and may be 100 μm or less.

From the viewpoint of increasing the hardness, the front surface plate 101 is preferably a film in which a hard coat layer is provided on at least one surface of the base film. As the base film, a film made of the resin can be used. The hard coat layer can be formed on one side of the base film or on both sides. By providing a hard coat layer, a resin film with improved hardness and scratch resistance can be made. The hard coat layer is, for example, a cured layer of ultraviolet curable resin. Examples of ultraviolet curable resins include acrylic resins, silicone resins, polyester resins, urethane resins, amide resins, and epoxy resins. In order to increase the hardness, the hard coat layer may contain additives. The additives are not limited, and examples include inorganic fine particles, organic fine particles, or a mixture of these.

In the case where the front surface plate 101 is a glass plate, the glass plate is preferably a tempered glass for display. The thickness of the glass plate may be, for example, 10 μm or more and 500 μm or less. By using a glass plate, the front surface plate 101 having excellent mechanical strength and surface hardness can be constructed.

In the case where the laminated body 100 is used in a display device, the front surface plate 101 may not only have a function of protecting the front surface (screen) of the display device (function as a window film), but also have a function as a touch sensor, Blu-ray cutoff function, viewing angle adjustment function, etc.

[The first adhesive layer] The first adhesive layer 102 is a layer that is interposed between the front surface plate 101 and the polarizer layer 103 and is bonded together. For example, it can be a layer containing an adhesive or an adhesive, or a layer formed by performing some treatment on the layer.的层。 The layer. The first adhesive layer may be an adhesive layer arranged at a position closest to the front surface plate among the adhesive layers constituting the laminate. Adhesives are also called pressure-sensitive adhesives. The term "adhesive" in this specification refers to an adhesive other than an adhesive (pressure-sensitive adhesive), and is clearly distinguished from an adhesive. The first adhesive layer 102 may include one layer, or may include two or more layers, preferably one layer.

The first adhesive layer 102 may be formed of the adhesive composition A as described above.

From the viewpoint of suppressing cracks, the first adhesive layer 102 preferably has a tan δ at a temperature of -40°C of 1.6 or more and 1.9 or less.

The thickness of the first adhesive layer 102 is, for example, preferably 3 μm or more and 100 μm or less, more preferably 5 μm or more and 50 μm or less, and may also be 20 μm or more.

[Polarizer layer] As the polarizer layer 103, a stretched film or stretched layer to which a dichroic dye is adsorbed, a layer obtained by applying and curing a composition containing a dichroic dye and a polymerizable compound, and the like can be cited. As the dichroic dye, specifically, iodine or a dichroic organic dye can be used. Dichroic organic dyes include dichroic direct dyes containing C.I. DIRECT RED 39 and other bisazo compounds, and dichroic direct dyes containing compounds such as trisazo and tetrasazo.

Examples of the polarizer layer formed by coating and curing a composition containing a dichroic dye and a polymerizable compound include coating a composition containing a liquid crystal dichroic pigment, or containing a dichroic pigment and A polarizer layer containing a cured product of a polymerizable liquid crystal compound, such as a layer obtained by curing a polymerizable liquid crystal composition. Compared with a stretched film or stretched layer on which a dichroic dye is adsorbed, there is no restriction on the bending direction of the polarizer layer formed by coating and curing a composition containing a dichroic dye and a polymerizable compound. Better.

[Polarizer layer which is stretched film or stretched layer] The polarizer layer of the stretched film that adsorbs the dichroic dye can usually be manufactured through the following steps: the step of uniaxially stretching the polyvinyl alcohol-based resin film; The step of dyeing the film to adsorb the dichroic pigment; the step of treating the polyvinyl alcohol resin film with the dichroic pigment adsorbed with the boric acid aqueous solution; and the step of washing with water after the treatment with the boric acid aqueous solution. The thickness of the polarizer layer 103 is, for example, 2 μm or more and 40 μm or less. The thickness of the polarizer layer 103 may be 5 μm or more, and may be 20 μm or less, further may be 15 μm or less, and further may be 10 μm or less.

Polyvinyl alcohol-based resin is obtained by saponifying polyvinyl acetate-based resin. As the polyvinyl acetate-based resin, in addition to polyvinyl acetate which is a homopolymer of vinyl acetate, a copolymer of vinyl acetate and other monomers that can be copolymerized therewith can also be used. Examples of other monomers that can be copolymerized with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and (meth)acrylamides having an ammonium group.

The degree of saponification of the polyvinyl alcohol-based resin is usually about 85 mol% or more and 100 mol% or less, preferably 98 mol% or more. The polyvinyl alcohol-based resin may be modified. For example, polyvinyl formal or polyvinyl acetal modified with aldehydes may also be used. The degree of polymerization of the polyvinyl alcohol-based resin is usually 1,000 or more and 10,000 or less, preferably 1,500 or more and 5,000 or less.

The polarizer layer that is the stretched layer to which the dichroic dye is adsorbed can generally be manufactured through the following steps: a step of applying a coating liquid containing the polyvinyl alcohol-based resin on a base film; and laminating the resulting laminate The step of uniaxial stretching of the film; the step of dyeing the polyvinyl alcohol-based resin layer of the uniaxially stretched laminate film with a dichroic dye to adsorb the dichroic dye to prepare a polarizer; using boric acid The step of treating the film with the dichroic dye adsorbed by the aqueous solution; and the step of washing with water after the treatment with the aqueous boric acid solution. If necessary, the base film can be peeled and removed from the polarizer layer. The material and thickness of the base film may be the same as the material and thickness of the thermoplastic resin film described later.

The polarizer layer, which is a stretched film or stretched layer, may be assembled in a laminate in a form in which a thermoplastic resin film is bonded on one or both sides. This thermoplastic resin film can function as a protective film for the polarizer layer 103 or a retardation film. The thermoplastic resin film may include, for example, polyolefin resins such as chain polyolefin resins (polypropylene resins, etc.), cyclic polyolefin resins (norbornene resins, etc.); cellulose resins such as triacetyl cellulose. Resins; polyester resins such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate; polycarbonate resins; (meth)acrylic resins; or these The mixture of the film.

From the viewpoint of thinning, the thickness of the thermoplastic resin film is generally 300 μm or less, preferably 200 μm or less, more preferably 100 μm or less, still more preferably 80 μm or less, and still more preferably 60 μm or less. In addition, It is usually 5 μm or more, preferably 20 μm or more.

The thermoplastic resin film may or may not have a phase difference.

The thermoplastic resin film can be bonded to the polarizer layer 103 using an adhesive layer, for example.

[Polarizer layer formed by coating and curing a composition containing a dichroic dye and a polymerizable compound] Examples of the polarizer layer formed by applying and curing a composition containing a dichroic dye and a polymerizable compound include a composition containing a polymerizable dichroic dye having liquid crystallinity, or a composition containing a dichroic dye A polarizer layer containing a cured product of a polymerizable liquid crystal compound, such as a layer obtained by applying and curing a composition of a polymerizable liquid crystal to a base film.

If necessary, the base film can be peeled and removed from the polarizer layer. The material and thickness of the base film may be the same as the material and thickness of the thermoplastic resin film. The polarizer layer may include an alignment film. The alignment film can also be peeled off.

The polarizer layer formed by applying and curing a composition containing a dichroic dye and a polymerizable compound can be assembled in an optical laminate in a form in which a thermoplastic resin film is bonded on one or both sides. As the thermoplastic resin film, the same ones as those that can be used in the polarizer layer which is a stretched film or a stretched layer can be used. The thermoplastic resin film can be bonded to the polarizer layer using an adhesive layer, for example.

The polarizer layer formed by coating and hardening a composition containing a dichroic dye and a polymerizable compound can also form an overcoat (OC) layer as a protective layer on one or both sides. Examples include photocurable resins and water-soluble polymers. Examples of the photocurable resin include (meth)acrylic resins, urethane resins, (meth)acrylate urethane resins, epoxy resins, and silicone resins. Examples of water-soluble polymers include: poly(meth)acrylamide-based polymers; polyvinyl alcohol and ethylene-vinyl alcohol copolymer, ethylene-vinyl acetate copolymer, (meth)acrylic acid or its anhydride- Vinyl alcohol polymers such as vinyl alcohol copolymers; carboxyvinyl polymers; polyvinylpyrrolidone; starches; sodium alginate; polyethylene oxide polymers, etc. The thickness of the OC layer is preferably 20 μm or less, more preferably 15 μm or less, further preferably 10 μm or less, may be 5 μm or less, and may be 0.05 μm or more, or may be 0.5 μm or more.

The thickness of the polarizer layer obtained by coating and curing a composition containing a dichroic dye and a polymerizable compound is usually 10 μm or less, preferably 0.5 μm or more and 8 μm or less, more preferably 1 μm or more and Below 5 μm.

[Second Adhesive Layer] The second adhesive layer 104 is an adhesive layer arranged between the polarizer layer 103 and the back plate 105. The second adhesive layer may be an adhesive layer arranged at a position closest to the back plate among the adhesive layers constituting the laminate. The second adhesive layer 104 may be one layer, or may include two or more layers, preferably one layer.

The second adhesive layer 104 may be formed of the adhesive composition A as described above. Regarding the thickness of the second adhesive layer, the temperature of the second adhesive layer at -40° C., the tan δ and the range thereof are the same as those shown in the description of the first adhesive layer 102. The second adhesive layer 104 may be the same as or different from the first adhesive layer 102 in terms of the composition of the adhesive composition and the blending ingredients, the thickness, and the tanδ at a temperature of -40°C.

[Back Panel] As the back plate 105, a plate-shaped body capable of transmitting light, a structural member used in a normal display device, or the like can be used.

The thickness of the back plate 105 may be, for example, 5 μm or more and 2,000 μm or less, preferably 10 μm or more and 1,000 μm or less, and more preferably 15 μm or more and 500 μm or less.

The plate-shaped body used for the back panel 105 may be composed of only one layer, may include two or more layers, and the plate-shaped body exemplified in the front panel 101 may be used.

Examples of constituent members used in a normal display device used for the back panel 105 include isolation films, touch sensor panels, organic EL display elements, and the like. Examples of the stacking order of the components in the display device include: front surface plate/circular polarizing plate/isolation film, front surface plate/circular polarizing plate/organic EL display element, front surface plate/circular polarizing plate/touch sensor Sensor panel/organic EL display element, front panel/touch sensor panel/circular polarizer/organic EL display element, etc.

(Touch sensor panel) As the touch sensor panel, as long as it is a sensor that can detect the touched position, the detection method is not limited, and examples include resistive film method, electrostatic capacitance coupling method, photo sensor method, ultrasonic method, Touch sensor panels of electromagnetic induction coupling method and surface acoustic wave method. In terms of low cost, touch sensor panels of resistive film method and electrostatic capacitance coupling method can be preferably used.

An example of a touch sensor panel of a resistive film method includes a pair of substrates arranged facing each other, an insulating spacer sandwiched between the pair of substrates, and a resistive film provided on the inner front surface of each substrate Transparent conductive film, and touch position detection circuit. In an image display device provided with a resistive film type touch sensor panel, if the surface of the front panel is touched, the opposing resistive films are short-circuited, and current flows through the resistive film. The touch position detection circuit detects the voltage change at this time, thereby detecting the touched position.

An example of the touch sensor panel of the capacitive coupling method includes a substrate, a transparent electrode for position detection provided on the entire surface of the substrate, and a touch position detection circuit. In the image display device provided with the touch sensor panel of the electrostatic capacitance coupling method, if the surface of the front surface plate is touched, the transparent electrode is grounded via the electrostatic capacitance of the human body at the touched point. The touch position detection circuit detects the grounding of the transparent electrode, thereby detecting the touched position.

The thickness of the touch sensor panel may be, for example, 5 μm or more and 2,000 μm or less, or may be 5 μm or more and 100 μm or less.

[Phase Difference Layer] The laminated body 100 may further include one or more retardation layers. The retardation layer is usually arranged between the polarizer layer 103 and the back plate 105. The retardation layer may be laminated on the first adhesive layer 102 and the second adhesive layer 104, or may be laminated on other layers via a layer other than these layers containing an adhesive or adhesive (hereinafter also referred to as an adhesive layer) (Including other retardation layers).

[Laminated layer] The bonding layer is a layer disposed between the first adhesive layer 102 and the second adhesive layer 104, and is a layer containing an adhesive or an adhesive. The adhesive constituting the bonding layer may be the same as exemplified for the adhesive composition constituting the first adhesive layer 102 or the second adhesive layer, or other adhesives, such as (meth)acrylic adhesives. Adhesives, styrene-based adhesives, silicone-based adhesives, rubber-based adhesives, urethane-based adhesives, polyester-based adhesives, epoxy-based copolymer adhesives, etc.

As the adhesive that constitutes the bonding layer, for example, it can be formed by combining one or two or more of water-based adhesives, active energy ray curable adhesives, adhesives, and the like. Examples of the water-based adhesive include a polyvinyl alcohol-based resin aqueous solution, an aqueous two-component urethane-based emulsion adhesive, and the like. The active energy ray-curable adhesive is an adhesive that is cured by irradiating active energy rays such as ultraviolet rays. Examples include those containing polymerizable compounds and photopolymerizable initiators, those containing photoreactive resins, and those containing adhesives. Resins and photoreactive crosslinkers, etc. Examples of the polymerizable compound include photopolymerizable monomers such as photocurable epoxy monomers, photocurable acrylic monomers, and photocurable urethane monomers, or those derived from these monomers. Body oligomers, etc. Examples of the photopolymerization initiator include those containing active species such as neutral radicals, anionic radicals, and cationic radicals by irradiating active energy rays such as ultraviolet rays.

The thickness of the bonding layer may be, for example, 1 μm or more, preferably 1 μm or more and 25 μm or less, more preferably 2 μm or more and 15 μm or less, and still more preferably 2.5 μm or more and 5 μm or less.

The laminate 200 shown in FIG. 2 includes a front surface plate 101, a first adhesive layer 102, a polarizer layer 103, a bonding layer 108 and a back plate 105, and further includes a first retardation layer 106, a bonding layer 109, and a Two retardation layer 107 and second adhesive layer 104.

Examples of the retardation layer include a positive A plate such as a λ/4 plate or a λ/2 plate, and a positive C plate. The retardation layer may be, for example, a retardation film that can be formed from the thermoplastic resin film, or a layer formed by curing a polymerizable liquid crystal compound, that is, a layer containing a cured product of a polymerizable liquid crystal compound, and the latter is preferred. The thickness of the retardation film may be the same as the thickness of the thermoplastic resin film. The thickness of the retardation layer formed by curing the polymerizable liquid crystal compound is, for example, 0.1 μm or more and 10 μm or less, preferably 0.5 μm or more and 8 μm or less, and more preferably 1 μm or more and 6 μm or less.

The retardation layer formed by curing the polymerizable liquid crystal compound can be formed by applying a composition containing the polymerizable liquid crystal compound to a base film and curing it. An alignment layer may also be formed between the base film and the coating layer. The material and thickness of the base film may be the same as the material and thickness of the thermoplastic resin film. The retardation layer formed by curing the polymerizable liquid crystal compound may be assembled in the laminate 100 in a form having an alignment layer and/or a base film. The back plate 105 may also be a base film for coating the composition.

As described above, the bonding layer 108 may use an adhesive or an adhesive. The adhesive may be the adhesive composition A. As the adhesive, a water-based adhesive or an active energy ray curable adhesive can be used. As an aqueous adhesive agent, the adhesive agent containing a polyvinyl alcohol-type resin aqueous solution, an aqueous two-component type urethane type emulsion adhesive agent, etc. are mentioned.

The so-called active energy ray curable adhesive refers to an adhesive that is cured by irradiating active energy rays such as ultraviolet rays. Examples include: those containing polymerizable compounds and photopolymerization initiators, those containing photoreactive resins, and those containing adhesive Agent resin and photoreactive crosslinking agent. Examples of the polymerizable compound include photopolymerizable monomers such as photocurable epoxy monomers, photocurable (meth)acrylic monomers, and photocurable urethane monomers, or those derived from Oligomers of photopolymerizable monomers, etc. Examples of the photopolymerization initiator include a photopolymerization initiator containing a substance that generates active species such as neutral radicals, anionic radicals, and cationic radicals by irradiation with active energy rays such as ultraviolet rays. As the active energy ray curable adhesive containing a polymerizable compound and a photopolymerization initiator, those containing a photocurable epoxy-based monomer and a photocationic polymerization initiator can be preferably used.

[Method of manufacturing laminate] The laminate 100 can be manufactured by a method including the steps in which the layers constituting the laminate 100 are bonded to each other through an adhesive layer or further through an adhesive layer. When bonding layers to each other via an adhesive layer or an adhesive layer, in order to improve adhesion, it is preferable to perform surface activation treatment such as corona treatment on one or both sides of the bonding surface. The polarizer layer 103 can be directly formed on a thermoplastic resin film or a base film, and the thermoplastic resin film or base film may be assembled in the laminate 100 or may be peeled from the polarizer layer 103 and not used as a component of the laminate.

＜Display device＞ The display device of the present invention includes the laminate 100 of the present invention. The display device is not particularly limited, and examples thereof include image display devices such as organic EL display devices, inorganic EL display devices, liquid crystal display devices, and electroluminescence display devices. The display device may also have a touch panel function. The optical laminate is suitable for a display device having flexibility that can be bent or folded.

In the display device, the optical laminate has the front surface plate facing outward (the side opposite to the display element side, that is, the visible side), and is arranged on the visible side of the display element included in the display device.

The display device of the present invention can be used as mobile devices such as smart phones, input panels, televisions, digital photo frames, electronic billboards, measuring devices or meters, office equipment, medical equipment, computer equipment, etc.

＜Adhesive composition＞ The adhesive composition of the present invention is an adhesive composition containing a (meth)acrylic polymer and a monofunctional (meth)acrylic monomer having an alkoxy group, and the (meth)acrylic polymer , Based on the total mass of the polymer, the constituent units derived from the monomer having a reactive functional group are less than 5% by mass. The adhesive composition of the present invention has excellent adhesion durability in a low-temperature environment, and therefore is suitable as a material for forming an adhesive layer of a laminate.

Types and molecular weights of monomers constituting (meth)acrylic polymers, types of monofunctional (meth)acrylic monomers with alkoxy groups, types and contents of reactive functional groups, adhesive composition Examples of the composition of the adhesive composition, the type of the adhesive composition, and the additives that can be blended in the adhesive composition are the same as those exemplified in the description of the adhesive composition A.

The adhesive composition of the present invention can be produced by mixing the components together using a known method, for example, using a mixer.

＜Adhesive sheet＞ The adhesive sheet of the present invention includes an adhesive layer formed of the adhesive composition of the present invention. The adhesive layer can be formed by coating the adhesive composition on the substrate. In the case of using an active energy ray-curable adhesive composition as the adhesive composition, by irradiating the formed adhesive layer with active energy rays, a cured product having a desired degree of curing can be obtained.

The substrate may be a release film that has been subjected to mold release treatment. The adhesive sheet can be produced by pre-forming a layer containing an adhesive on the release film into a sheet shape, and then attaching another release film on the adhesive layer.

The adhesive sheet of the present invention has excellent adhesive durability in a low temperature environment. In addition, the tan δ at a temperature of -40°C of the pressure-sensitive adhesive sheet of the present invention is 1.5 or more and 2.0 or less. Therefore, when the adhesive sheet of the present invention is used for a laminate, the laminate tends to be excellent in flexibility at low temperatures. From the viewpoint of suppressing cracks in the adhesive layer, the tan δ at the temperature of the adhesive sheet at −40° C. is preferably 1.6 or more and 1.9 or less. The tanδ at a temperature of -40°C can be measured in accordance with the measurement method described in the column of Examples described later.

Hereinafter, the present invention will be explained in more detail with examples, but the present invention is not limited by these examples. [Example]

[Layer thickness] The measurement was performed using a contact-type film thickness measuring device ("MS-5C" manufactured by Nikon Co., Ltd.). Among them, the polarizer layer and the alignment film were measured using a laser microscope (“OLS3000” manufactured by Olympus Co., Ltd.).

[Tanδ at -40°C] A viscoelasticity measuring device (MCR-301, Anton Paar) was used to measure tanδ at -40°C. The same adhesive sheet used in the Examples and Comparative Examples was cut into a width 30 mm×length 30 mm. The peeling film was peeled off from the adhesive sheet, and multiple sheets were laminated so that the thickness of the adhesive layer was 150 μm and joined to the glass plate. In the state where the adhesive layer is bonded to the measurement wafer, measure at a temperature range of -40°C to 100°C, under the conditions of a frequency of 1.0 Hz, a deformation amount of 1%, and a heating rate of 5°C/min. Confirm the temperature of -40 Measured value of tanδ at °C. Furthermore, tanδ has the following relationship with storage elasticity coefficient G'and loss elasticity coefficient G". [Number 1]

[Low temperature flexibility (-20℃)] The laminates obtained in the respective examples and comparative examples were subjected to a low-temperature bendability test as follows. 3(a) and 3(b) are diagrams schematically showing the method of this evaluation test. First, peel off the heavy-duty isolation film of the laminate, and attach a polyethylene terephthalate (PET) film (thickness 100 μm). A bending device (manufactured by Science Town, STS-VRT-500) having two stages 501 and 502 is prepared, and the laminated body 100 is placed on the stages 501 and 502 (FIG. 3( a )). The distance (gap) C between the two stages 501 and 502 is set to 6 mm (3R). The table 501 and the table 502 can swing centered on the (gap) C between the two tables, and the two tables 501 and 502 initially form the same plane. Rotate the two tables 501, 502 upward by 90 degrees with the position P1 and the position P2 as the center of the rotation axis to close the two tables 501, 502 (Figure 3(b)), open the tables 501 and 502 again, This action is defined as a bend. This operation is repeatedly performed, and the number of bending times until cracks are first generated in the laminate 100 is counted. The evaluation criteria are as follows. ◎(Excellent): More than 20,000 times, 〇 (good): more than 10,000 times but less than 20,000 times, △(Can be used): more than 5,000 times and less than 10,000 times, × (slightly worse): more than 10,000 times and less than 5,000 times, ××(poor): less than 0.1 million times

[Low temperature adhesion durability (-40℃)] The laminate obtained in each of the Examples and Comparative Examples was cut into a width of 100 mm × a length of 100 mm. Peel off the heavy isolating film and attach it to the alkali-free glass. In an autoclave (50°C, 5 atmospheres), it is crimped for about 20 minutes and kept under constant temperature and humidity conditions (23°C, 50%RH) for 4 hours. Put the sample in an oven at -40°C, and judge whether there is floating, peeling, or bubbles after 250 hours. ○: Almost no appearance changes such as floating, peeling, and foaming are observed. △: The appearance changes such as floating, peeling, and foaming are slightly noticeable. ×: Appearance changes such as floating, peeling, and foaming are clearly seen.

[Weight average molecular weight (Mw)] The weight average molecular weight (Mw) of the (meth)acrylic polymer is the number average molecular weight (Mn) converted to polystyrene. Tetrahydrofuran is used in the mobile phase, and the following particle size sieve chromatography (size exclusion chromatography, SEC). The measured (meth)acrylic polymer was dissolved in tetrahydrofuran at a concentration of about 0.05% by mass, and 10 μL was injected into a size exclusion chromatograph (SEC). The mobile phase flows at a flow rate of 1.0 mL/min. As the column, PLgel MIXED-B (manufactured by Polymer Laboratories) was used. The detector used an ultraviolet-visible light detector (UV-VIS detector) (trade name: Agilent GPC).

<Example 1> [Preparation of (meth)acrylic polymer A1] 54 parts by mass of n-butyl acrylate, 45 parts by mass of 2-ethylhexyl acrylate, and 1 part by mass of 4-hydroxybutyl acrylate were copolymerized to prepare (meth)acrylic polymer A1. The molecular weight of the (meth)acrylic polymer A1 was measured by the method described later, and as a result, the weight average molecular weight (Mw) was 800,000.

[Preparation of adhesive composition] The (meth)acrylic polymer A1 obtained in the above step of 100 parts by mass (solid content conversion value; the same below) was modified with trimethylolpropane as the thermal crosslinking agent B to xylylene diisocyanate ( 0.25 parts by mass, manufactured by Soken Chemical Co., Ltd., product name "TD-75"), and 3-glycidoxypropyltrimethoxysilane as silane coupling agent C (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KBM403") 0.2 The mass parts are mixed, fully stirred, and diluted with methyl ethyl ketone, thereby obtaining a coating solution of the adhesive composition.

[Manufacture of Adhesive Sheet] The coating solution of the obtained adhesive composition was applied to the release treatment surface of a light release film (manufactured by Lintec Corporation, product name "SP-PET752150") using a knife coater. Then, the coating layer was heat-treated at 90°C for 1 minute to form the coating layer. Then, the coating layer on the light release film and the heavy release film (manufactured by Lintec Co., Ltd., product name "SP-PET382120" ") Laminated and cured for 7 days under the conditions of 23°C and 50%RH to produce an adhesive sheet with an adhesive layer of thickness 25 μm, that is, including a light barrier film/adhesive layer (thickness: 25 μm) / Adhesive sheet composed of heavy isolation film. In addition, the thickness of the adhesive layer is the value measured by the said method. Table 1 shows each formulation (solid content conversion value) of the adhesive composition when the (meth)acrylic polymer A1 is set to 100 parts by mass (solid content conversion value). In addition, the details of the abbreviations and the like described in Table 1 are as follows. BA: n-butyl acrylate 2EHA: 2-ethylhexyl acrylate 4HBA: 4-hydroxybutyl acrylate

<Example 2 and Example 3> As shown in Table 1, the ratio of each monomer constituting the (meth)acrylic polymer A1, the weight average molecular weight (Mw) of the (meth)acrylic polymer A1, and the blending amount of the crosslinking agent were changed, except Otherwise, in the same manner as in Example 1, the (meth)acrylic polymer A2, the (meth)acrylic polymer A3, and these adhesive sheets were produced.

<Comparative Example 1 and Comparative Example 2> As shown in Table 1, the ratio of each monomer constituting the (meth)acrylic polymer A1, the weight average molecular weight (Mw) of the (meth)acrylic polymer A1, and the blending amount of the crosslinking agent were changed, except Otherwise, in the same manner as in Example 1, the (meth)acrylic polymer B1, (meth)acrylic polymer B2, and these adhesive sheets were produced.

[Table 1] (Meth) acrylic polymer Crosslinking agent Silane coupling agent Film thickness [μm] species BA 2EHA 4HBA Molecular weight (Mw) Example 1 A1 54 45 1 800 000 0.25 0.2 25 Example 2 A2 54 45 1 1.2 million 0.15 0.2 25 Example 3 A3 54 45 1 800 000 0.15 0.2 25 Comparative example 1 B1 45 45 10 150000 0.05 0.2 25 Comparative example 2 B2 45 45 10 1.8 million 1.00 0.2 25

<Comparative Example 3> [Production of Silurethane Acrylate Resin] Into a 2 L flask including an electronic stirrer, heating mantle, cooling tube, and temperature controller, put polyisocyanate, polysilicon with hydroxyl groups on both ends, and dilauric acid as a catalyst in the following parts by mass With dibutyltin, the reaction temperature was increased to 70°C while stirring, and the reaction was maintained for 4 hours. Thereafter, the (meth)acrylate having a hydroxyl group and methoxyhydroquinone as a polymerization inhibitor were reacted, and the injection was maintained for 2 hours. Polyisocyanate (4,4'-methylene dicyclohexyl diisocyanate, molecular weight 262): 524 parts by mass Polysilicon with hydroxyl groups at both ends (X-22-160AS, Shin-Etsu Chemical, molecular weight 933): 933 parts by mass Dibutyltin dilaurate: 0.4 parts by mass Methoxyhydroquinone: 0.3 parts by mass (Meth) acrylate with hydroxyl group (2-hydroxyethyl acrylate, molecular weight 116): 232 parts by mass

[Manufacturing of Adhesive Sheet] The adhesive composition was coated on a release film coated with a silicon release agent to a thickness of 25 μm, and the release film was bonded to it, and then a high-pressure UV lamp was used at 500 mJ/ The amount of light of cm ² makes the adhesive sheet.

<Example 4> [Preparation of (meth)acrylic polymer (A4)] In order to reflux the nitrogen gas and easily adjust the temperature, a 1 L reactor equipped with a cooling device is charged with 89.9% by mass of 2-ethylhexyl acrylate (2-EHA) monomer and 10% by mass of butyl acrylate (BA) monomer. After %% of the monomer mixture, nitrogen was refluxed for 1 hour in order to remove oxygen, and the temperature was maintained at 80°C. After the monomer mixture was uniformly mixed, the photopolymerization initiator benzil dimethyl ketal (I-651) 0.05% by mass and 1-hydroxycyclohexyl phenyl ketone (I-184) 0.05% by mass were added. Then, a UV lamp (10 mW) was irradiated while stirring to produce a (meth)acrylate polymer (A4) with a weight average molecular weight (Mw) of 330,000. Table 2 collectively shows the ratio of each component.

[Manufacture of Adhesive Sheet] The adhesive composition manufactured with the composition shown in Table 3 was applied to a light release film (polyethylene terephthalate film, thickness 38 μm) coated with a silicon release agent in a thickness of 25 μm on. A heavy barrier film (polyethylene terephthalate film, thickness 38 μm) was bonded to it, and UV irradiation was performed to produce an adhesive sheet including a light barrier film/adhesive layer/heavy barrier film. In addition, the details of the abbreviations and the like described in Table 3 are as follows. EOEOEA: ethoxy ethoxy ethyl acrylate NP(EO)8A: Nonylphenol EO modified acrylate

<Example 5> [Preparation of (meth)acrylic polymer (A5)] In order to reflux the nitrogen gas and easily adjust the temperature, a 1 L reactor equipped with a cooling device was charged with 89.9% by mass of 2-ethylhexyl acrylate (2-EHA) monomer and 4 mass% of butyl acrylate (BA) monomer. %, 6% by mass of lauryl acrylate (LA) monomer, after refluxing for 1 hour in order to remove oxygen, the temperature was maintained at 80°C. After the monomer mixture was uniformly mixed, the photopolymerization initiator benzil dimethyl ketal (I-651) 0.05% by mass and 1-hydroxycyclohexyl phenyl ketone (I-184) 0.05% by mass were added. Then, a UV lamp (10 mW) was irradiated while stirring to produce a (meth)acrylate polymer (A5) with a weight average molecular weight (Mw) of 400,000.

[Manufacture of Adhesive Sheet] In the same manner as in Example 4, an adhesive sheet was produced using the adhesive composition manufactured with the composition shown in Table 3.

<Example 6> [Preparation of (meth)acrylic polymer (A6)] In order to reflux the nitrogen gas and easily adjust the temperature, a 1 L reactor equipped with a cooling device was charged with 89.9% by mass of 2-ethylhexyl acrylate (2-EHA) monomer and 6 mass% of lauryl acrylate (LA) monomer. %, 4% by mass of isodecyl acrylate (IDA) monomer, after refluxing for 1 hour in order to remove oxygen, the temperature was maintained at 80°C. After the monomer mixture was uniformly mixed, the photopolymerization initiator benzil dimethyl ketal (I-651) 0.05% by mass and 1-hydroxycyclohexyl phenyl ketone (I-184) 0.05% by mass were added. Next, a UV lamp (10 mW) was irradiated while stirring to produce a (meth)acrylate polymer (A6) with a weight average molecular weight (Mw) of 400,000.

[Manufacture of Adhesive Sheet] In the same manner as in Example 4, an adhesive sheet was produced using the adhesive composition manufactured with the composition shown in Table 3.

[Table 2] (Meth) acrylic polymer Molecular weight (Mw) species 2EHA BA LA IDA I-651 I-184 Example 4 A4 89.9 10 - - 0.05 0.05 330,000 Example 5 A5 89.9 4 6 - 0.05 0.05 400000 Example 6 A6 89.9 - 6 4 0.05 0.05 400000

[table 3] (Meth) acrylic polymer Monofunctional monomer with alkoxy group Photopolymerization initiator Film thickness [μm] species Allocation amount (mass%) species Allocation amount (mass%) species Allocation amount (mass%) Example 4 A4 94.95 EOEOEA 5 I-184 0.05 25 Example 5 A5 91.95 EOEOEA 8 I-184 0.05 25 Example 6 A6 96.95 NP(EO)8A 3 I-184 0.05 25

The pressure-sensitive adhesive sheets produced in Examples 1 to 6 and Comparative Examples 1 to 3 were subjected to measurement of tan δ at a temperature of -40°C. The results are shown in Table 4.

[Front Panel (Window Film)] As the front surface plate, a polyimide film (thickness 50 μm) with a hard coat layer (thickness 10 μm) on one side was prepared.

[Polarizer layer] 1. Prepare the following materials. 1) Triacetyl cellulose (TAC) film with a thickness of 25 μm. 2) Composition for forming alignment film. [Polymer 1] Prepared polymer 1 which has a photoreactive group containing the following structural unit. [化1]

A solution obtained by dissolving the polymer 1 in cyclopentanone at a concentration of 5% by mass was used as a composition for forming an alignment film [hereinafter also referred to as a composition (D-1)].

[化3]

3) The composition for forming a polarizer layer [polymerizable liquid crystal compound] The polymerizable liquid crystal compound uses a polymerizable liquid crystal compound represented by formula (1-1) [hereinafter also referred to as compound (1-1)] and formula (1- 2) The represented polymerizable liquid crystal compound [hereinafter also referred to as compound (1-2)]. [化2]

[化3]

Compound (1-1) and Compound (1-2) were obtained by Lub et al. (Lub et al.) "Recl. Trav. Chim. Pays-Bas", 115, 321-328 ( The method described in 1996) was synthesized.

[化5]

[化6]

[Dichroic Dye] The dichroic dye is described in the examples of Japanese Patent Laid-Open No. 2013-101328, which are represented by the following formulas (2-1a), (2-1b), and (2-3a) The azo pigment. [化4]

[化5]

[化6]

The composition for forming a polarizer layer [hereinafter also referred to as composition (A-1)] is prepared by the following method: 75 parts by weight of compound (1-1), 25 parts by weight of compound (1-2), and two 2.5 parts by weight each of the azo dyes represented by the formula (2-1a), formula (2-1b), and formula (2-3a) of the chromatic dye, 2-dimethylamino group as a polymerization initiator -2-benzyl-1-(4-morpholinophenyl)butan-1-one (Irgacure 369, manufactured by BASF Japan) 6 parts by weight, and as a leveling agent 1.2 parts by weight of the polyacrylate compound (BYK-361N, manufactured by BYK-Chemie) was mixed with 400 parts by weight of toluene as a solvent, and the resulting mixture was stirred at 80°C for 1 hour.

4) Composition for forming protective layer (OC layer) The composition for forming the protective layer (OC layer) [hereinafter also referred to as composition (E-1)] is made by mixing water: 100 parts by mass, polyvinyl alcohol resin powder (Kuraray) (stock), average Polymerization degree 18000, trade name: KL-318): 3 parts by weight, polyamide epoxy resin (crosslinking agent, manufactured by Sumika Chemtex (stock), trade name: SR650 (30)): 1.5 It is prepared by mixing parts by weight.

2. Production method 1) The composition for forming an alignment film is applied to the TAC film side in the following manner. First, corona treatment is applied to the TAC film side once. The conditions of corona treatment were set to output 0.3 kW and processing speed 3 m/min. After that, the composition (D-1) obtained as described above was coated on the TAC by a bar coating method, and heated and dried in a drying oven at 80° C. for 1 minute. The obtained dry film was subjected to a polarization UV irradiation treatment to form a first alignment film (AL1). Polarized UV treatment is to make light irradiated from the UV irradiation device (SPOT CURE SP-7; manufactured by Usio Electric Co., Ltd.) pass through the wire grid (UIS-27132##, manufactured by Ushio Electric Co., Ltd.) And it is performed under the condition that the cumulative light intensity measured at a wavelength of 365 nm is 100 mJ/cm ² . The thickness of the first alignment film (AL1) is 100 nm. 2) The composition for forming a polarizer layer is applied to the alignment film side in the following manner. First, on the formed first alignment film (AL1), the composition (A-1) was applied by a bar coating method, heated and dried in a drying oven at 120° C. for 1 minute, and then cooled to room temperature. Using the UV irradiation device, ultraviolet rays were irradiated to the dry film at a cumulative light amount of 1200 mJ/cm ² (365 nm reference), thereby forming a polarizer layer (pol). The thickness of the obtained polarizer layer (pol) was measured by a laser microscope (OLS3000 manufactured by Olympus Co., Ltd.), and the result was 1.8 μm. In this way, a laminate including "TAC/AL1/pol" is obtained. 3) The composition for forming a protective layer (OC layer) is applied to the polarizer layer side as follows. On the formed polarizer layer (pol), the composition (E-1) was applied by a bar coating method, coated so that the thickness after drying was 1.0 μm, and dried at a temperature of 80° C. for 3 minutes. In this way, a laminate including "TAC film/cPL (AL1+pol+protective layer)" is obtained.

[Retardation layer] 1. Material preparation Prepare the following materials. 1) A PET film with a thickness of 100 μm. 2) Composition for forming alignment film. [Polymer 1] Prepared polymer 1 which has a photoreactive group containing the following structural unit. [化7]

A solution obtained by dissolving the polymer 1 in cyclopentanone at a concentration of 5% by weight was used as a composition for forming an alignment film [hereinafter also referred to as a composition (D-1)].

3) The composition for forming a retardation layer mixes the components shown below, and the resulting mixture is stirred at 80°C for 1 hour to obtain a composition (B-1). Compound b-1 represented by the following formula: 80 parts by mass [Chemical Formula 8]

Compound b-2 represented by the following formula: 20 parts by mass [Chemical Formula 9]

Polymerization initiator (Irgacure 369, 2-dimethylamino-2-benzyl-1-(4-morpholinophenyl) butan-1-one, BASF Japan) Made by the company): 6 parts by mass Leveling agent (BYK-361N, polyacrylate compound, manufactured by BYK-Chemie): 0.1 parts by mass Solvent (cyclopentanone): 400 parts by mass

2. Production method 1) The composition for forming an alignment film is applied to a PET film in the following manner. Prepare a polyethylene terephthalate film (PET) with a thickness of 100 μm as a substrate, apply the composition (D-1) on the film by a bar coating method, and heat and dry it in a drying oven at 80°C 1 minute. The obtained dry film is subjected to a polarization UV irradiation treatment to form a second alignment film (AL2). The polarized UV treatment was performed using the UV irradiation device described above under the condition that the cumulative light amount measured at a wavelength of 365 nm was 100 mJ/cm ² . In addition, it was performed so that the polarization direction of the polarized light UV was 45° with respect to the absorption axis of the polarizer layer. In this way, a laminate including "base material (PET)/second alignment film (AL2)" is obtained. 2) The composition for forming a retardation layer is applied to the alignment film side of the PET film in the following manner. On the third alignment film (AL2) of the first substrate obtained in this way, the composition (B-1) was coated by a bar coating method, heated and dried in a drying oven at 120°C for 1 minute, and then cooled to the chamber temperature. The obtained dry film was irradiated with ultraviolet rays having a cumulative light intensity of 1000 mJ/cm ² (based on 365 nm) using the UV irradiation device to form a retardation layer. The thickness of the obtained retardation layer was measured by a laser microscope (OLS3000 manufactured by Olympus Co., Ltd.) and it was 2.0 μm. The retardation layer is a λ/4 plate (Quarter-Wave Plate (QWP)) that displays a λ/4 retardation value in the in-plane direction. In this way, a laminate including "base material (PET)/AL2/QWP" is obtained.

[Share adhesive sheet] 1) Polymerization of acrylic resin The following components were reacted at 55°C while stirring in a nitrogen atmosphere, thereby obtaining an acrylic resin. Butyl acrylate: 70 parts by mass Methyl acrylate: 20 parts by mass Acrylic: 2.0 parts by mass Radical polymerization initiator (2,2'-azobisisobutyronitrile): 0.2 parts by mass 2) Liquid adjustment of adhesive composition The following components are mixed to obtain an adhesive composition. Acrylic resin: 100 parts by mass Crosslinking agent ("Coronate L" manufactured by Tosoh Corporation): 1.0 parts by mass Silane coupling agent ("X-12-981" manufactured by Shin-Etsu Silicon Co., Ltd.): 0.5 parts by mass Ethyl acetate was added so that the total solid content concentration might be 10% by mass to obtain an adhesive composition.

3) Manufacturing of adhesive sheets Using an applicator, apply the resulting adhesive composition to a release-treated polyethylene terephthalate film (heavy release film, thickness 38 μm) so that the thickness after drying is 5 μm. Mold processing surface. The coating layer was dried at 100°C for 1 minute to obtain a film including an adhesive layer. Thereafter, another polyethylene terephthalate film (light barrier film, thickness 38 μm) subjected to mold release treatment was attached to the exposed surface of the adhesive layer. Thereafter, it was cured for 7 days under the conditions of a temperature of 23° C. and a relative humidity of 50% RH to obtain a light isolation film/common adhesive layer/heavy isolation film.

<Example 7> The laminate was manufactured in the following procedure. First, prepare a laminate 410 including the polarizer layer [TAC film 301/cPL ((AL1+pol)302/OC layer 303)] and the common adhesive sheet 420 (light isolation film 304/common adhesive layer 305). /Re-isolation film 306) (Figure 4(a)). The OC layer 303 side of the laminated body 410 including the polarizer layer and the surface of the common adhesive sheet 420 from which the light separation film 304 was peeled were corona treated (output 0.3 KW, speed 3 m/min), and then bonded to obtain Laminated body a 430. The retardation layer 440 [base material (PET) 308/AL2/QWP 307] is prepared (FIG. 4(b)).

Next, corona treatment (output 0.3 KW, speed 3 m/min) was performed on the QWP 307 side of the phase difference layer 440 and the surface of the heavy isolation film 306 of the laminate a, and then bonded to obtain a laminate b 450 . After that, the adhesive sheet 460 (light isolation film 309/adhesive layer 310/heavy isolation film 311) produced in Example 1 was prepared (FIG. 4(c)).

The surface of the laminate b 450 from which the base material (PET) 308 is peeled off and the surface of the adhesive sheet 460 from which the light separator 309 is peeled off are subjected to corona treatment (output 0.3 KW, speed 3 m/min), and then bonded, A laminate c 470 is obtained. Furthermore, the adhesive sheet 490 (light isolation film 314/adhesive layer 315/heavy isolation film 316) produced in Example 1 was prepared, and the surface from which the light isolation film 314 was peeled off and the front surface plate 480 (polyimide The polyimide film 313 side of the film 313/hard coat layer 312) is corona treated (output 0.3 KW, speed 3 m/min), and then bonded to obtain a laminate d 500 (Figure 4(d)) .

The surface of the laminate d 500 from which the heavy isolation film 316 was peeled off and the TAC 301 side of the laminate c 470 were subjected to corona treatment (output 0.3 KW, speed 3 m/min), and then bonded to obtain the laminate of Example 7 Body 300 (Figure 4(e)). The results are shown in Table 4.

<Example 8 to Example 12 and Comparative Example 4 to Comparative Example 6> Except that the adhesive sheet shown in Table 4 was used instead of the adhesive sheet produced by Example 1 in Example 7, a laminate was produced in the same manner as in Example 7. The results are shown in Table 4.

[Table 4] Example Comparative example 7 8 9 10 11 12 4 5 6 Type of Adhesive Sheet Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative example 1 Comparative example 2 Comparative example 3 Tanδ at -40℃ 1.87 1.71 1.68 1.69 1.89 1.92 2.71 1.01 2.42 Low temperature flexibility (-20℃) ◎ 〇 〇 ◎ 〇 〇 ×× ×× ×× Low temperature adhesion durability (-40℃) 〇 〇 〇 〇 〇 〇 X X △

100, 200, 300: laminated body 101, 480: front surface plate 102: The first adhesive layer 103: Polarizer layer 104: second adhesive layer 105: back panel 106: first phase difference layer 107: second retardation layer 108, 109: Laminated layer 301: TAC film 302:pol 303: OC layer 304, 309, 314: light isolation film 305: Shared adhesive layer 306, 311, 316: heavy isolation membrane 307: QWP 308: Substrate (PET) 310, 315: Adhesive layer 312: Hard coating 313: Polyimide film 410: Laminated body including polarizer layer 420: shared adhesive sheet 430: Laminated body a 440: retardation layer 450: Laminated body b 460, 490: Adhesive sheet 470: layered body c 500: layered body d 501, 502: Taiwan C: The distance between the two stations (gap) P1, P2: location

Fig. 1 is a schematic cross-sectional view showing an example of the laminate of the present invention. Fig. 2 is a schematic cross-sectional view showing an example of the laminate of the present invention. 3(a) and 3(b) are schematic diagrams for explaining the method of the bendability test. 4(a) to 4(e) are cross-sectional views schematically showing the method of manufacturing the laminate of the present invention.

100: layered body

101: front panel

102: The first adhesive layer

103: Polarizer layer

104: second adhesive layer

105: back panel

Claims (8)

A laminated body, including in order: a front surface plate, a first adhesive layer, a polarizer layer, a second adhesive layer and a back plate, The first adhesive layer and the second adhesive layer both have a tanδ of 1.5 or more and 2.0 or less at a temperature of -40°C, and are formed of an adhesive composition containing a (meth)acrylic polymer, In the (meth)acrylic polymer, the structural unit derived from a monomer having a reactive functional group is less than 5% by mass based on the total mass of the polymer. The laminate according to claim 1, wherein the front surface plate is a film in which a hard coat layer is provided on at least one surface of a base film. The laminate according to claim 1 or 2, wherein the weight average molecular weight (Mw) of the (meth)acrylic polymer is 200,000 or more and 1.5 million or less. The laminate according to any one of claims 1 to 3, wherein the adhesive composition further contains a monofunctional (meth)acrylic monomer having an alkoxy group. The laminated body according to any one of claim 1 to claim 4, wherein the back panel is a touch sensor panel. A display device includes the laminate according to any one of claim 1 to claim 5. An adhesive composition comprising: a (meth)acrylic polymer and a monofunctional (meth)acrylic monomer having an alkoxy group, and In the (meth)acrylic polymer, the structural unit derived from a monomer having a reactive functional group is less than 5% by mass based on the total mass of the polymer. An adhesive sheet comprising an adhesive layer formed of the adhesive composition according to claim 7.

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