JP2023068424A - Laminate and manufacturing method therefor - Google Patents

Abstract

To provide a laminate which comprises two retardation layers bonded together via a water-based adhesive and offers good adhesion between the retardation layers even when at least one of light transmittance values of the two retardation layers constituting the laminate is 10% or less at a wavelength of 380 nm.SOLUTION: A laminate is provided, comprising a first retardation layer and a second retardation layer laminated together via a water-based adhesive layer, where the first and second retardation layers comprise cured product layers of a polymerizable liquid crystal compound and at least one of light transmittance values of the first and second retardation layers is 10% or less at a wavelength of 380 nm.SELECTED DRAWING: Figure 1

Description

The present invention relates to laminates and also to methods of manufacturing laminates.

Patent Literature 1 describes a laminate in which retardation layers are bonded together via an active energy ray-curable adhesive.

JP 2018-017996 A

When the retardation layers are bonded together via an active energy ray-curable adhesive, if the light transmittance of one of the retardation layers is low, the amount of light of the active energy ray irradiated to the adhesive layer is reduced. Accordingly, sufficient adhesion between the retardation layers may not be obtained.
In addition, when using an adhesive that cures with light in the visible light wavelength range, which has high light transmittance in the retardation layer, it is necessary to take measures in terms of production facilities to prevent the adhesive from unintentionally curing. It was difficult to apply.
Furthermore, when laminating thin film retardation layers with each other via an active energy ray-curable adhesive, the thickness of the adhesive layer tends to be thicker than when laminating with a water-based adhesive. In addition, the curing shrinkage of the adhesive causes wrinkles and the like, which may impair the appearance quality of the laminate.

The present invention is a laminate in which two retardation layers are bonded via a water-based adhesive, and at least one of the light transmittance at a wavelength of 380 nm of the two retardation layers constituting the laminate An object of the present invention is to provide a laminate having good adhesion between retardation layers even when the content is 10% or less.

The present invention provides the following laminate and method for producing the laminate.
[1] The first retardation layer and the second retardation layer are laminated via a water-based adhesive layer,
The first retardation layer and the second retardation layer comprise a cured layer of a polymerizable liquid crystal compound,
At least one of the first retardation layer and the second retardation layer has a light transmittance of 10% or less at a wavelength of 380 nm.
[2] One of the first retardation layer and the second retardation layer is a quarter-wave retardation layer with reverse wavelength dispersion, and the other is a positive C-plate, [1] The laminate according to .
[3] further comprising a first base film and a second base film,
The first base film is arranged on the side opposite to the water-based adhesive layer side of the first retardation layer,
The laminate according to [1] or [2], wherein the second base film is disposed on the side of the second retardation layer opposite to the water-based adhesive layer.
[4] The moisture permeability of the first base film and the second base film at a temperature of 40° C. and a relative humidity of 90% RH are both 200 g/m ² ·24 hr or less, according to [3]. laminate.
[5] A first step of forming a coating film of a water-based adhesive on the first retardation layer;
a second step of drying the coating film of the water-based adhesive to form a water-based adhesive layer;
After applying a surface activation treatment to the surface of the aqueous adhesive layer opposite to the first retardation layer side, the first retardation layer and the second retardation layer are attached to the aqueous adhesive layer. a third step of laminating via an agent layer;
in this order,
The method for producing a laminate, wherein at least one of the first retardation layer and the second retardation layer has a light transmittance of 10% or less at a wavelength of 380 nm.
[6] The method for manufacturing a laminate according to [5], further comprising a curing step of heating the laminate after the third step.
[7] In the second step,
A step of laminating a release film on the coating film of the water-based adhesive;
After drying the coating film of the water-based adhesive layer, peeling the release film;
The method for manufacturing a laminate according to [5] or [6], further comprising:

According to the present invention, a laminate in which two retardation layers are bonded via a water-based adhesive, and at least any of the light transmittance at a wavelength of 380 nm of the two retardation layers constituting the laminate Even when one of them is 10% or less, it is possible to provide a laminate having good adhesion between the retardation layers.

It is a schematic sectional drawing which shows an example of the layer structure of the laminated body of this invention. FIG. 4 is a schematic cross-sectional view showing another example of the layer structure of the laminate of the present invention. It is a schematic sectional drawing which shows an example of the layer structure of the polarizing plate provided with the laminated body of this invention. It is a schematic sectional drawing which shows an example of the manufacturing method of the laminated body of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments. In all the drawings below, the scale of each component is adjusted appropriately to facilitate understanding, and the scale of each component shown in the drawings does not necessarily match the scale of the actual component.

<Laminate>
In the laminate of the present invention, the first retardation layer and the second retardation layer are bonded via a water-based adhesive layer, and the first retardation layer and the second retardation layer are polymerizable Including a cured layer of a liquid crystal compound, at least one of the first retardation layer and the second retardation layer has a light transmittance of 10% or less at a wavelength of 380 nm. In this specification, the first retardation layer and the second retardation layer may be collectively referred to as a retardation layer. Also, the first base film and the second base film, which will be described later, may be collectively referred to as a base film. In addition, "laminated" means a state in which two layers are in contact with each other and adhered.

A laminate of the present invention will be described with reference to FIG. A laminate 10 shown in FIG. 1 includes a first retardation layer 11, a water-based adhesive layer 12, and a second retardation layer 13 in this order. Although not shown, the laminate 10 may have other layers such as a first base film, a second base film, an alignment film, etc., which will be described later.

At least one of the first retardation layer 11 and the second retardation layer 13 has a light transmittance of 10% or less at a wavelength of 380 nm. When a water-based adhesive is used for adhesion of the retardation layers, heat deterioration of the retardation layer may occur due to heating for removing moisture from the water-based adhesive. Therefore, conventionally, an active energy curable adhesive has been used for adhesion between retardation layers. However, if at least one of the light transmittance at a wavelength of 380 nm of the two retardation layers is 10% or less, the active energy curable adhesive is not sufficiently cured, and the adhesion between the retardation layers is insufficient. It happened to be. The laminate of the present invention tends to have excellent interlayer adhesion, although at least one of the two retardation layers has a light transmittance of 10% or less at a wavelength of 380 nm. Moreover, the laminate 10 of the present invention can be superior in appearance quality as compared with the case of using an active energy ray-curable adhesive.

The light transmittance of either the first retardation layer 11 or the second retardation layer 13 at a wavelength of 380 nm may be, for example, 10% or less, and may be 5% or less. The light transmittance at a wavelength of 380 nm of either one of the first retardation layer 11 and the second retardation layer 13 may be, for example, 0% or more, preferably 3% or more. Both the first retardation layer 11 and the second retardation layer 13 may have a light transmittance at a wavelength of 380 nm, for example, 10% or less, 5% or less, or 0% or more. may be 3% or more. The first retardation layer 11 and the second retardation layer 13 may have the same or different light transmittance at a wavelength of 380 nm. The light transmittance at a wavelength of 380 nm can be measured according to the method described in the Examples section below.

In the laminate 10, the adhesion between the water-based adhesive layer 12 and the second retardation layer 13 may be, for example, 1 N/25 mm or more, preferably 1.5 N/25 mm or more, more preferably 2 N/25 mm. That's it. In the laminate 10, the adhesive strength between the water-based adhesive layer 12 and the second retardation layer 13 is usually 20 N/25 mm or less, 15 N/25 mm or less, or 10 N/25 mm or less. Adhesion can be measured according to the method described in the Examples section below.

In the laminate 10, the adhesion between the water-based adhesive layer 12 and the first retardation layer 11 may be, for example, 1 N/25 mm or more, preferably 1.5 N/25 mm or more, more preferably 2 N/25 mm. That's it. In the laminate 10, the adhesive strength between the water-based adhesive layer 12 and the first retardation layer 11 is usually 20 N/25 mm or less, 15 N/25 mm or less, or 10 N/25 mm or less. Adhesion can be measured according to the method described in the Examples section below.

(retardation layer)
The retardation layer includes a cured layer of a polymerizable liquid crystal compound (hereinafter also simply referred to as a cured layer). The cured layer is a layer having retardation characteristics, and is a cured layer in which a polymerizable liquid crystal compound is polymerized and cured in an aligned state to exhibit retardation characteristics. The first retardation layer 11 and the second retardation layer 13 may have the same type of hardened layer or different types of hardened layer. The thickness of the first retardation layer 11 and the thickness of the second retardation layer 13 may be the same or different.

The retardation layer can be a half-wave retardation layer, a quarter-wave retardation layer or a positive C-plate. When the retardation layer is a quarter-wave retardation layer, the retardation layer preferably has reverse wavelength dispersion from the viewpoint of enhancing adhesion. Both the first retardation layer 11 and the second retardation layer 13 may have reverse wavelength dispersion.

The reverse wavelength dispersion is an optical property in which the liquid crystal alignment in-plane retardation value at a short wavelength is smaller than the liquid crystal alignment in-plane retardation value at a long wavelength. i) and formula (ii) are satisfied. Note that Re(λ) represents an in-plane retardation value for light with a wavelength of λnm.
Re(450)/Re(550)≤1 (i)
1≦Re(630)/Re(550) (ii)

One of the first retardation layer 11 and the second retardation layer 13 can be a reverse wavelength dispersive quarter-wave retardation layer and the other can be a positive C-plate. For example, the first retardation layer 11 and the second retardation layer 13 are a reverse wavelength dispersion quarter-wave retardation layer and a positive C plate, respectively.

The 1/2 wavelength retardation layer is a layer in which Re (λ) satisfies Re (λ) = λ/2, and may be achieved at any wavelength in the visible light range, especially at a wavelength of 550 nm. preferably achieved. Re(550) of the half-wave retardation layer preferably satisfies 200 nm≦Re(550)≦330 nm, more preferably 220 nm≦Re(550)≦300 nm. The 1/4 wavelength retardation layer is a layer in which Re (λ) satisfies Re (λ) = λ/4, and may be achieved at any wavelength in the visible light range, especially at a wavelength of 550 nm. preferably achieved. Re(550) of the quarter-wave retardation layer preferably satisfies 100 nm≦Re(550)≦160 nm, more preferably 110 nm≦Re(550)≦150 nm.

nx is the refractive index in the film in-plane slow axis direction (the direction in which the in-plane refractive index is maximized), ny is the refractive index in the direction perpendicular to the in-plane slow axis, and the refraction in the thickness direction A positive C plate satisfies the relationship of the following formula, where nz is the ratio.
nz>nx≈ny
The above "≈" includes not only the case where both are completely the same, but also the case where both are substantially the same.

The polymerizable liquid crystal compound includes a rod-like polymerizable liquid crystal compound and a disk-like polymerizable liquid crystal compound, and one of them may be used, or a mixture containing both of them may be used. When the rod-shaped polymerizable liquid crystal compound is aligned horizontally or vertically with respect to the substrate layer, the optical axis of the polymerizable liquid crystal compound coincides with the long axis direction of the polymerizable liquid crystal compound. When the discotic polymerizable liquid crystal compound is oriented, the optical axis of the polymerizable liquid crystal compound exists in a direction orthogonal to the discotic surface of the polymerizable liquid crystal compound. As the rod-like polymerizable liquid crystal compound, for example, those described in JP-A-11-513019 (claim 1 etc.) can be preferably used. As the discotic polymerizable liquid crystal compound, JP-A-2007-108732 (paragraphs [0020] to [0067], etc.), JP-A-2010-244038 (paragraphs [0013] to [0108], etc.) described in can be preferably used.

In order for the cured layer formed by polymerizing the polymerizable liquid crystal compound to exhibit an in-plane retardation, the polymerizable liquid crystal compound may be oriented in a suitable direction. When the polymerizable liquid crystal compound is rod-shaped, an in-plane retardation is expressed by aligning the optical axis of the polymerizable liquid crystal compound horizontally with respect to the plane of the base film described later. It coincides with the phase axis direction. When the polymerizable liquid crystal compound is disk-shaped, the in-plane retardation is expressed by orienting the optical axis of the polymerizable liquid crystal compound horizontally with respect to the plane of the base film described later. It is perpendicular to the phase axis. The alignment state of the polymerizable liquid crystal compound can be adjusted by a combination of the alignment film and the polymerizable liquid crystal compound.

A polymerizable liquid crystal compound is a compound having at least one polymerizable group and having liquid crystallinity. When two or more polymerizable liquid crystal compounds are used in combination, at least one preferably has two or more polymerizable groups in the molecule. A polymerizable group means a group that participates in a polymerization reaction, and is preferably a photopolymerizable group. Here, the photopolymerizable group means a group that can participate in a polymerization reaction by an active radical generated from a photopolymerization initiator described below, an acid, or the like. Examples of the polymerizable group include vinyl group, vinyloxy group, 1-chlorovinyl group, isopropenyl group, 4-vinylphenyl group, acryloyloxy group, methacryloyloxy group, oxiranyl group, oxetanyl group, styryl group and allyl group. be done. Among them, an acryloyloxy group, a methacryloyloxy group, a vinyloxy group, an oxiranyl group and an oxetanyl group are preferred, and an acryloyloxy group is more preferred. The liquid crystallinity of the polymerizable liquid crystal compound may be either thermotropic liquid crystal or lyotropic liquid crystal, and thermotropic liquid crystal may be classified into nematic liquid crystal or smectic liquid crystal according to the degree of order.

The retardation layer may contain an alignment film. The alignment film has an alignment control force that aligns the polymerizable liquid crystal compound in a desired direction. The alignment film may be a vertical alignment film in which the molecular axis of the polymerizable liquid crystal compound is vertically aligned with respect to the substrate layer, or a horizontal alignment film in which the molecular axis of the polymerizable liquid crystal compound is horizontally aligned with respect to the substrate layer. or a tilted alignment film in which the molecular axis of the polymerizable liquid crystal compound is tilted with respect to the substrate layer. When the retardation layer includes two or more alignment films, the alignment films may be the same or different.

The alignment film has a solvent resistance that does not dissolve when a composition for forming a liquid crystal layer containing a polymerizable liquid crystal compound is applied, etc., and has heat resistance to heat treatment for removing the solvent and aligning the polymerizable liquid crystal compound. things are preferred. Examples of the alignment film include an alignment polymer layer formed of an alignment polymer, a photo-alignment polymer layer formed of a photo-alignment polymer, and a groove alignment film having an uneven pattern or a plurality of grooves on the layer surface. can be done.

The thickness of the first retardation layer 11 and the second retardation layer 13 may be 0.1 μm or more, 0.5 μm or more, 1 μm or more, or 2 μm or more. Also, it is preferably 10 μm or less, may be 8 μm or less, or may be 5 μm or less.

The cured layer can be formed by applying a composition for forming a liquid crystal layer containing a polymerizable liquid crystal compound onto a substrate film described below, drying the composition, and polymerizing the polymerizable liquid crystal compound. The composition for forming a liquid crystal layer may be applied onto an alignment film formed on a substrate film, which will be described later.

The first retardation layer 11 and the second retardation layer 13 have a surface contact angle with water of, for example, 75° or less, preferably 70° or less from the viewpoint of enhancing adhesion, and more It is preferably 65° or less. The contact angle of water on the surface of the hardened layer can be measured according to the method described in Examples below.

(Water-based adhesive layer)
The water-based adhesive layer 12 can be arranged between the first retardation layer 11 and the second retardation layer 13 to bond them together. The water-based adhesive layer 12 may be a single layer or multiple layers.

The water-based adhesive layer 12 can be formed from a water-based adhesive. Examples of water-based adhesives include adhesives composed of a polyvinyl alcohol-based resin aqueous solution, water-based two-liquid type urethane-based emulsion adhesives, and the like. Among them, a water-based adhesive composed of an aqueous polyvinyl alcohol resin solution is preferably used. Polyvinyl alcohol-based resins include vinyl alcohol homopolymers obtained by saponifying polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate with other monomers copolymerizable therewith. A polyvinyl alcohol-based copolymer obtained by saponifying a polymer, or a modified polyvinyl alcohol-based polymer obtained by partially modifying the hydroxyl groups thereof can be used. The water-based adhesive can contain cross-linking agents such as aldehyde compounds (glyoxal, etc.), epoxy compounds, melamine compounds, methylol compounds, isocyanate compounds, amine compounds, polyvalent metal salts, and the like.

The content of the polyvinyl alcohol resin in the polyvinyl alcohol resin aqueous solution may be, for example, 1 part by mass or more and 50 parts by mass or less, preferably 1.5 parts by mass or more and 10 parts by mass or less, more preferably 100 parts by mass of water. is 2.5 parts by mass or more and 5 parts by mass or less.

The water-based adhesive layer 12 is formed by laminating the first retardation layer 11 and the second retardation layer 13 via a water-based adhesive, followed by a drying process for removing water contained in the water-based adhesive. It can be formed by implementation. By drying the water-based adhesive, the water-based adhesive layer 12 is formed, and the first retardation layer 11 and the second retardation layer 13 are bonded together.

The thickness of the water-based adhesive layer 12 is preferably 0.1 μm or more and 1 μm or less.

(Base film)
The base film can have the function of supporting the cured layer and the alignment film. As the base film, a translucent (preferably optically transparent) thermoplastic resin, such as a chain polyolefin resin (polypropylene resin, etc.), a cyclic polyolefin resin (norbornene resin, etc.). cellulose resins such as triacetyl cellulose and diacetyl cellulose; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; polycarbonate resins; (meth)acrylic resins such as methyl methacrylate resin; Polystyrene-based resin; polyvinyl chloride-based resin; acrylonitrile-butadiene-styrene-based resin; acrylonitrile-styrene-based resin; polyvinyl acetate-based resin; polyvinylidene chloride-based resin; polyamide-based resin; Polysulfone-based resins; polyethersulfone-based resins; polyarylate-based resins; polyamideimide-based resins; polyimide-based resins, and the like.

Examples of linear polyolefin resins include polyethylene resins (polyethylene resins that are homopolymers of ethylene and copolymers that are mainly composed of ethylene), polypropylene resins (polypropylene resins that are homopolymers of propylene, and propylene resins that are mainly composed of propylene). In addition to homopolymers of chain olefins such as copolymers that form a chain olefin, copolymers composed of two or more types of chain olefins can be mentioned.

Cyclic polyolefin-based resin is a general term for resins polymerized using cyclic olefins as polymerized units, and is described, for example, in JP-A-1-240517, JP-A-3-14882, and JP-A-3-122137. resins. Specific examples of cyclic polyolefin-based resins include ring-opening (co)polymers of cyclic olefins, addition polymers of cyclic olefins, copolymers of cyclic olefins and chain olefins such as ethylene and propylene (typically are random copolymers), graft polymers modified with unsaturated carboxylic acids or derivatives thereof, and hydrides thereof. Among them, norbornene-based resins using norbornene-based monomers such as norbornene and polycyclic norbornene-based monomers as cyclic olefins are preferably used.

Polyester-based resins are resins having an ester bond, excluding cellulose ester-based resins described below, and generally consist of a polycondensate of a polyhydric carboxylic acid or its derivative and a polyhydric alcohol. Divalent dicarboxylic acids or derivatives thereof can be used as polyvalent carboxylic acids or derivatives thereof, such as terephthalic acid, isophthalic acid, dimethyl terephthalate, and dimethyl naphthalenedicarboxylate. Dihydric diols can be used as polyhydric alcohols, such as ethylene glycol, propanediol, butanediol, neopentyl glycol, and cyclohexanedimethanol. A representative example of the polyester resin is polyethylene terephthalate, which is a polycondensate of terephthalic acid and ethylene glycol.

A (meth)acrylic resin is a resin containing a compound having a (meth)acryloyl group as a main constituent monomer. Specific examples of (meth)acrylic resins include, for example, poly(meth)acrylic acid esters such as polymethyl methacrylate; methyl methacrylate-(meth)acrylic acid copolymer; methyl methacrylate-(meth)acrylic acid Ester copolymer; methyl methacrylate-acrylic acid ester-(meth)acrylic acid copolymer; methyl (meth)acrylate-styrene copolymer (MS resin, etc.); (eg, methyl methacrylate-cyclohexyl methacrylate copolymer, methyl methacrylate-norbornyl (meth)acrylate copolymer, etc.). Preferably, a polymer containing poly (meth)acrylic acid C _1-6 alkyl ester as a main component such as polymethyl (meth)acrylate is used, more preferably methyl methacrylate as a main component (50 mass % 100% by mass or less, preferably 70% by mass or more and 100% by mass or less) is used.

Cellulose ester resin is an ester of cellulose and fatty acid. Specific examples of cellulose ester resins include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. Copolymers thereof and those in which a part of hydroxyl groups are modified with other substituents are also included. Among these, cellulose triacetate (triacetylcellulose) is particularly preferred.

Polycarbonate-based resins are engineering plastics composed of polymers in which monomer units are linked via carbonate groups.

Although the thickness of the base film is not particularly limited, it is generally preferably 1 μm or more and 300 μm or less, more preferably 20 μm or more and 200 μm or less, from the viewpoint of workability such as strength and handleability. The substrate film may be incorporated in the circularly polarizing plate together with the retardation layer, the substrate layer is peeled off, and only the retardation layer, or the retardation layer and the alignment film are incorporated in the circularly polarizing plate. good.

The first base film and the second base film may be composed of the same type of thermoplastic resin, or may be composed of different types of thermoplastic resins. Moreover, the thickness may be the same or may be different.

The light transmittance of the base film at a wavelength of 380 nm may be, for example, 95% or less, preferably 90% or less, and more preferably 85% or less. When the laminate includes the first base film and the second base film, the light transmittance at a wavelength of 380 nm of the first base film and the second base film may be the same or different. may be When the laminate comprises a first base film and a second base film, both the light transmittance at a wavelength of 380 nm of the first base film and the second base film are, for example, 95% or less. Well, preferably both are 90% or less, more preferably both are 85% or less.

The moisture permeability of the substrate film at a temperature of 40° C. and a relative humidity of 90% RH may be, for example, 200 g/m ² 24 hr or less, 150 g/m ² 24 hr or less, or 100 g/m ² 24 hr or less. . The moisture permeability of the substrate film at a temperature of 40° C. and a relative humidity of 90% RH may be, for example, 1 g/m ² ·24 hr or more, preferably 10 g/m ² ·24 hr or more, more preferably 50 g/m ² ·. 24 hours or more. When the laminate includes the first base film and the second base film, the first base film and the second base film have the same moisture permeability at a temperature of 40° C. and a relative humidity of 90% RH. may be different. The water vapor transmission rate at a temperature of 40° C. and a relative humidity of 90% RH can be measured according to the method described in Examples below.

FIG. 2 shows the layer structure of the laminate including the base film. The laminate 20 shown in FIG. 2 includes a first base film 21, a first retardation layer 11, a water-based adhesive layer 12, a second retardation layer 13, and a second base film 22. and in this order. The first base film 21 is arranged on the opposite side of the first retardation layer 11 to the water-based adhesive layer 12 side. The second base film 22 is arranged on the side of the second retardation layer 13 opposite to the water-based adhesive layer 12 side.

(Use of laminate)
The laminate of the invention can be used for a polarizing plate. The polarizing plate may be a circular polarizing plate in which the laminate 10 and a linear polarizing plate are laminated.

FIG. 3 is a schematic cross-sectional view showing an example of the layer structure of a polarizing plate. A polarizing plate 30 shown in FIG. 3 is formed by bonding a linear polarizing plate 31 and a laminate 10 via a bonding layer 32 . Linear polarizing plate 31 includes a polarizer (linear polarizer) 33 and a protective film 34 . The protective film 34 is attached to the polarizer 33 via an adhesive layer (not shown). The laminate 10 is arranged on the protective film 34 side of the linear polarizing plate 31 .

(Polarizer)
Examples of the polarizer 33 include a stretched film or stretched layer to which a dichroic dye is adsorbed, and a polarizer layer formed by applying and curing a dichroic dye. A polarizer layer formed by applying and curing a dichroic dye is preferred because there is no restriction in the bending direction compared to a stretched film or stretched layer to which a dye having anisotropic absorption is adsorbed.

Specifically, iodine and dichroic organic dyes are used as dichroic dyes. Dichroic organic dyes include, for example, azo dyes. Examples of azo dyes include C.I. I. Dichroic direct dyes composed of disazo compounds such as DIRECT RED 39 and dichroic direct dyes composed of compounds such as trisazo and tetrakisazo are included.

(Stretched film or stretched layer to which dichroic dye is adsorbed)
The stretched film to which the dichroic dye is adsorbed is usually produced by the process of uniaxially stretching the polyvinyl alcohol resin film, and the process of dyeing the polyvinyl alcohol resin film with the dichroic dye to adsorb the dichroic dye. , a step of treating a polyvinyl alcohol-based resin film to which a dichroic dye is adsorbed with an aqueous boric acid solution, and a step of washing with water after the treatment with the aqueous boric acid solution.
The thickness of the stretched film to which the dichroic dye is adsorbed may be, for example, 2 μm or more and 40 μm or less, may be 5 μm or more, may be 20 μm or less, further 15 μm or less, and furthermore may be 10 μm or less. .

A polyvinyl alcohol-based resin is obtained by saponifying a polyvinyl acetate-based resin. Polyvinyl acetate-based resins include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith. Other monomers copolymerizable with vinyl acetate include, for example, unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and (meth)acrylamides having an ammonium group.

The degree of saponification of the polyvinyl alcohol resin is generally about 85 mol % or more and 100 mol % or less, preferably 98 mol % or more. The polyvinyl alcohol-based resin may be modified, and for example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used. The degree of polymerization of the polyvinyl alcohol resin is usually 1000 or more and 10000 or less, preferably 1500 or more and 5000 or less.

The stretched layer to which the dichroic dye is adsorbed is usually formed by applying a coating liquid containing the polyvinyl alcohol resin onto the substrate film, uniaxially stretching the resulting laminated film, and uniaxially stretching the laminated film. A step of dyeing the polyvinyl alcohol-based resin layer with a dichroic dye to adsorb the dichroic dye to form a polarizer layer, and a step of treating the film on which the dichroic dye is adsorbed with an aqueous boric acid solution. , and washing with water after treatment with an aqueous boric acid solution.
If necessary, the base film may be peeled off from the stretching layer to which the dichroic dye is adsorbed. The material and thickness of the base film may be the same as the material and thickness of the base film described in the above description of the retardation layer.

(Polarizer layer formed by applying and curing a dichroic dye)
The polarizer layer obtained by coating and curing a dichroic dye is a composition containing a polymerizable dichroic dye having liquid crystallinity or a composition containing a polymerizable liquid crystal compound and a dichroic dye as a base material. A polarizer layer containing a cured product of a polymerizable liquid crystal compound, such as a layer obtained by coating and curing a film, may be mentioned. The substrate film may be provided with an alignment film on one surface. The polarizer 33 is preferably a layer containing a cured product of a composition containing a polymerizable liquid crystal compound and one or more azo dyes and an alignment film from the viewpoint of improving flexibility. The thickness of the alignment film may be, for example, 5 nm or more and 1 μm or less.

The polarizer 33 may be incorporated in the polarizing plate 30 together with the base film, or may be incorporated in the polarizing plate 30 by peeling and removing the base film from the polarizer layer formed by applying a dichroic dye and curing it. good too. The material and thickness of the base film may be the same as the material and thickness of the base film described in the above description of the retardation layer. A hard coat layer (HC layer) may be formed on at least one surface of the base film as a protective layer, which will be described later.

The thickness of the polarizer layer formed by coating and curing the dichroic dye is usually 10 μm or less, preferably 8 μm or less, and more preferably 5 μm or less.

(Protective film)
The protective film 34 can have the function of protecting the surface of the polarizer 33 . Although the protective film 34 is arranged on one side of the polarizer 33 in FIG. 3 , the protective films may be arranged on both sides of the polarizer 33 .

As the protective film 34, a thermoplastic resin film that constitutes the base film described in the above explanation of the retardation layer can be used. The thickness of the protective film 34 is usually 300 μm or less, preferably 200 μm or less, more preferably 100 μm or less, even more preferably 50 μm or less, and even more preferably 30 μm or less, from the viewpoint of thinning. Also, it is usually 1 μm or more, and may be, for example, 5 μm or more or 20 μm or more.

The protective film 34 can be bonded to the polarizer 33 via a bonding layer, which will be described later. The bonding layer for bonding the thermoplastic resin film to the polarizer 33 is preferably an adhesive layer.

[Lamination layer]
The bonding layer 32 can be an adhesive layer composed of an adhesive or an adhesive layer composed of an adhesive. Adhesives are also called pressure-sensitive adhesives. As used herein, the term "adhesive" refers to an adhesive other than a pressure-sensitive adhesive (pressure-sensitive adhesive), and is clearly distinguished from a pressure-sensitive adhesive. The pressure-sensitive adhesive layer may consist of one layer or two or more layers, preferably one layer. The pressure-sensitive adhesive layer can be formed from the pressure-sensitive adhesive composition.

The pressure-sensitive adhesive layer can be composed of a pressure-sensitive adhesive composition whose main component is a (meth)acrylic, rubber, urethane, ester, silicone, or polyvinyl ether resin. Among them, a pressure-sensitive adhesive composition using a (meth)acrylic resin as a base polymer, which is excellent in transparency, weather resistance, heat resistance, etc., is preferable. The adhesive composition may be active energy ray-curable or heat-curable.

Examples of the (meth)acrylic resin (base polymer) used in the adhesive composition include butyl (meth)acrylate, ethyl (meth)acrylate, isooctyl (meth)acrylate, and 2-(meth)acrylate. Polymers or copolymers containing one or more of (meth)acrylic acid esters such as ethylhexyl as monomers are preferably used. Preferably, the base polymer is copolymerized with a polar monomer. Examples of polar monomers include (meth)acrylic acid, 2-hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate, (meth)acrylamide, N,N-dimethylaminoethyl (meth)acrylate, glycidyl ( Monomers having a carboxyl group, a hydroxyl group, an amide group, an amino group, an epoxy group, etc., such as meth)acrylates, can be mentioned.

The pressure-sensitive adhesive composition may contain only the above base polymer, but usually further contains a cross-linking agent. The cross-linking agent is a metal ion having a valence of 2 or more, which forms a carboxylic acid metal salt with a carboxyl group; a polyamine compound, which forms an amide bond with a carboxyl group; Examples include epoxy compounds and polyols that form ester bonds with carboxyl groups; and polyisocyanate compounds that form amide bonds with carboxyl groups. Among them, polyisocyanate compounds are preferred.

The active energy ray-curable pressure-sensitive adhesive composition has the property of being cured by being irradiated with an active energy ray such as an ultraviolet ray or an electron beam. It is a pressure-sensitive adhesive composition that can be adhered to an adherend such as the adhesive agent, and that can be cured by irradiation with an active energy ray to adjust the adhesion force. The active energy ray-curable pressure-sensitive adhesive composition is preferably UV-curable. The active energy ray-curable pressure-sensitive adhesive composition further contains an active energy ray-polymerizable compound in addition to the base polymer and the cross-linking agent. Furthermore, if necessary, a photopolymerization initiator, a photosensitizer, and the like may be contained.

The adhesive composition contains fine particles for imparting light scattering properties, beads (resin beads, glass beads, etc.), glass fibers, resins other than base polymers, tackifiers, fillers (metal powders and other inorganic powders). etc.), antioxidants, ultraviolet absorbers, dyes, pigments, colorants, antifoaming agents, corrosion inhibitors, antistatic agents, photopolymerization initiators, and other additives.

The pressure-sensitive adhesive layer can be formed by applying an organic solvent-diluted solution of the above pressure-sensitive adhesive composition onto a substrate and drying it. When an active energy ray-curable pressure-sensitive adhesive composition is used, a cured product having a desired degree of curing can be obtained by irradiating the formed pressure-sensitive adhesive layer with an active energy ray.

The thickness of the pressure-sensitive adhesive layer is, for example, preferably 1 μm or more and 100 μm or less, more preferably 50 μm or less, and may be 20 μm or more.

As the adhesive that constitutes the bonding layer 32, for example, one or a combination of two or more of water-based adhesives, active energy ray-curable adhesives, pressure-sensitive adhesives, and the like can be used. As the water-based adhesive, those exemplified in the above description of the water-based adhesive layer can be used. The active energy ray-curable adhesive is an adhesive that cures when irradiated with an active energy ray such as ultraviolet rays. For example, one containing a polymerizable compound and a photopolymerization initiator, one containing a photoreactive resin, Examples include those containing a binder resin and a photoreactive cross-linking agent. Examples of the polymerizable compound include photopolymerizable monomers such as photocurable epoxy monomers, photocurable acrylic monomers, and photocurable urethane monomers, and oligomers derived from these monomers. Examples of the photopolymerization initiator include those containing substances that generate active species such as neutral radicals, anion radicals, and cation radicals upon irradiation with active energy rays such as ultraviolet rays.

When an adhesive layer is used as the bonding layer 32, the thickness is preferably 1 μm or more, may be 5 μm or more, and is usually 200 μm or less, for example, 150 μm or less or 100 μm or less. When an adhesive layer is used as the bonding layer, the thickness of the bonding layer is preferably 0.1 μm or more, may be 0.5 μm or more, is preferably 10 μm or less, and is preferably 5 μm or less. There may be.

The polarizing plate 30 can be used in an image display device. The image display device is not particularly limited, and examples thereof include an organic electroluminescence (organic EL) display device, an inorganic electroluminescence (inorganic EL) display device, a liquid crystal display device, a touch panel display device, an electroluminescence display device, and the like. . The polarizing plate 30 can be placed on the viewing side (front side) of the image display device, or can be placed on the back side.

<Method for manufacturing laminate>
The method for producing a laminate of the present invention includes a first step of forming a coating film of a water-based adhesive on the first retardation layer, and drying the coating film of the water-based adhesive to form a water-based adhesive layer. After performing a second step and surface activation treatment on the surface of the water-based adhesive layer opposite to the first retardation layer side, the first retardation layer and the second through the water-based adhesive layer and a third step of laminating the second retardation layer in this order, and at least one of the first retardation layer and the second retardation layer has a light transmittance of 10% or less at a wavelength of 380 nm. . For the first retardation layer, the water-based adhesive layer, and the second retardation layer, the first retardation layer 11, the water-based adhesive layer 12, and the second retardation layer 13 in the laminate 10 described above, respectively. Description applies.

At least one of the first retardation layer and the second retardation layer has a light transmittance of 10% or less at a wavelength of 380 nm. When a water-based adhesive is used for adhesion of the retardation layers, heat deterioration of the retardation layer may occur due to heating for removing moisture from the water-based adhesive. Therefore, conventionally, an active energy curable adhesive has been used for adhesion between retardation layers. However, if at least one of the retardation layers has a light transmittance of 10% or less at a wavelength of 380 nm, the active energy curable adhesive is not sufficiently cured, and the adhesion between the retardation layers becomes insufficient. something happened. According to the method for producing a laminate of the present invention, it is possible to produce a laminate having excellent interlayer adhesion even though any of the retardation layers has a light transmittance of 10% or less at a wavelength of 380 nm. It becomes possible. Moreover, according to the production method of the present invention, it is easier to obtain a laminate having excellent appearance quality compared to the case of using an active energy ray-curable adhesive.

A method for manufacturing a laminate according to the present invention will be described with reference to FIG. In the first step, a water-based adhesive coating 45 is formed on the first retardation layer 41 [FIG. 4(a)]. The method of applying the water-based adhesive onto the first retardation layer 41 can be performed, for example, by a conventionally known method. In the method for producing a laminate of the present invention, the retardation layer can be produced according to the method described above, and the retardation layer may contain at least one of an alignment film and a substrate film. , the base film may be removed. Although not shown, when the first retardation layer 41 includes a base film, a water-based adhesive coating 45 is formed on the surface of the first retardation layer 41 side. Although not shown, the surface of the first retardation layer 41 may be subjected to a surface activation treatment from the viewpoint of easily improving adhesion.

In the second step, the water-based adhesive coating 45 is dried to form a water-based adhesive layer 46 [FIG. 4(b)]. The second step is a step of laminating a release film 47 on the coating film 45 of the water-based adhesive [FIG. A step of peeling after forming the agent layer 46 [FIG. 4(b2)] can be further provided. As a method for drying the coating film 45 of the water-based adhesive, for example, a conventionally known method can be used. The drying temperature of the water-based adhesive coating film 45 may be, for example, 20° C. or higher and 90° C. or lower. The drying time of the water-based adhesive coating film 45 may be, for example, 1 minute or more and 60 minutes or less.

The release film 47 is preferably composed of a plastic film and a release layer. In the third step, the plastic film to be used preferably has a moisture permeability of 200 g/m ² ·24 hr or more from the viewpoint of sufficiently removing moisture from the adhesive when drying the water-based adhesive. Examples of plastic films include triacetyl cellulose resin (TAC) films. Also, the release layer can be formed, for example, from a release layer-forming composition. The main component (resin) constituting the release layer-forming composition is not particularly limited, but examples thereof include silicone resins, alkyd resins, acrylic resins, and long-chain alkyl resins.

In the third step, the surface of the water-based adhesive layer 46 opposite to the first retardation layer 41 side is subjected to surface activation treatment, and then the first retardation layer 41 and the second retardation layer 42 are formed. are laminated through a water-based adhesive layer 46 to obtain a laminate 40 [FIG. 4(c)]. By applying the surface activation treatment, the adhesion between the water-based adhesive layer and the second retardation layer 42 can be easily improved. Although not shown, when the second retardation layer 42 includes a base film, the surface on the side of the second retardation layer 42 is used as the bonding surface with the water-based adhesive layer 46 . Examples of surface activation treatment include dry treatments such as corona treatment, plasma treatment, discharge treatment (glow discharge treatment, etc.), ozone treatment, UV ozone treatment, ionizing active ray treatment (ultraviolet treatment, electron beam treatment, etc.). can be done. These surface activation treatments may be performed singly or in combination of two or more. Among them, corona treatment is preferred. Corona treatment can be performed at an output of, for example, 1 kJ/m ² or more and 50 kJ/m ² or less. The time for corona treatment may be, for example, 1 second or more and 1 minute or less. Although not shown, the bonding surface of the second retardation layer 42 to the water-based adhesive layer 46 may also be subjected to a surface activation treatment from the viewpoint of facilitating improved adhesion.

Although not shown, in the method for manufacturing the laminate of the present invention, the laminate 40 is removed after the third step in order to facilitate the improvement of the adhesion between the adhesive layer 46 and the second retardation layer 42. A curing step for curing can be further provided. In the curing step, the laminate may be heated. In the curing step, the temperature for heating the laminate 40 may be, for example, 20° C. or higher and 90° C. or lower, preferably 40° C. or higher and 90° C. or lower, more preferably 60° C. or higher and 90° C. or lower, and particularly preferably 75° C. °C or higher and 85 °C or lower. In the curing step, the time for curing the laminate 40 can be, for example, 1 minute or more and 2 hours or less.

In the laminate 40 obtained by the manufacturing method of the present invention, the adhesion between the water-based adhesive layer 46 and the first retardation layer 41 may be, for example, 1 N/25 mm or more, preferably 1.5 N/ 25 mm or more, more preferably 2 N/25 mm or more. In the laminate 40, the adhesive strength between the water-based adhesive layer 46 and the first retardation layer 41 is usually 20 N/25 mm or less, 15 N/25 mm or less, or 10 N/25 mm or less. Adhesion can be measured according to the method described in the Examples section below.

In the laminate 40, the adhesive strength between the water-based adhesive layer 46 and the second retardation layer 42 may be, for example, 1 N/25 mm or more, preferably 1.5 N/25 mm or more, more preferably 2 N/25 mm. That's it. In the laminate 40, the adhesive strength between the water-based adhesive layer 46 and the second retardation layer 42 is usually 20 N/25 mm or less, 15 N/25 mm or less, or 10 N/25 mm or less. Adhesion can be measured according to the method described in the Examples section below.

The present invention will be described in more detail below with reference to examples. Unless otherwise specified, "%" and "parts" in the examples are mass % and mass parts.

(Measurement of light transmittance)
The retardation layer was cut into a size of 30 mm×30 mm, and the transmittance [%] was measured at a wavelength of 200 to 510 nm. For the measurement, an ultraviolet-visible spectrophotometer "UV-2450" manufactured by Shimadzu Corporation was used.

(Measurement of moisture permeability)
Using a constant temperature and humidity chamber, the water vapor transmission rate was measured by the moisture permeability test method (cup method, according to JIS Z 0208) under the measurement conditions of temperature of 40° C., relative humidity of 90% RH, and measurement time of 24 hours. The measured water vapor transmission rate was defined as water vapor transmission rate [%] at a temperature of 40° C. and a relative humidity of 90% RH.

(Measurement of water contact angle)
The water contact angle to be measured after surface treatment under the same conditions as when producing the laminate is the water contact angle to be measured. That is, after performing corona treatment on the surfaces of the first retardation layer and the second retardation layer in Examples and Comparative Examples, the contact angle meter ( Kyowa Interface Science Co., Ltd., image processing type contact angle meter "FACE CA-X type") is set horizontally, 1 μL of pure water is dropped at the measurement position, and the water contact angle is measured by the θ / 2 method. . The measurement position was about 200 mm from one end in the width direction of the laminate for measurement.

(Thickness measurement)
The thickness of the layer was measured using a contact-type film thickness measuring device ("MS-5C" manufactured by Nikon Corporation). The thicknesses of the water-based adhesive layer, the polarizer, and the alignment film were measured using a laser microscope ("OLS3000" manufactured by Olympus Corporation).

(Evaluation of adhesion)
The laminate was cut to a width of 25 mm. A triacetylcellulose-based resin (TAC) film (thickness: 40 μm) was laminated via an adhesive on the surface of the retardation layer exposed by peeling the first base film from the cut laminate, and then a second film was applied. A glass plate is attached via an adhesive to the surface of the retardation layer exposed by peeling off the base film of TAC film / adhesive / retardation layer / water-based adhesive layer / retardation layer / adhesive / A measurement sample having a layer structure of a glass plate was obtained. Using a precision universal testing machine "Autograph AGS-50NX" manufactured by Shimadzu Corporation, the TAC film of the measurement sample to the water-based adhesive layer is grasped and the adhesive strength is measured by measuring the force when peeling in the 180 ° direction. was measured. The measurement was performed at a peeling speed of 300 mm/min under an environment of a temperature of 23±2° C. and a relative humidity of 50±5%. The following evaluation criteria were used.
◯: Adhesion was good, and the part of the layer that was gripped during measurement was destroyed.
Δ: Adhesion could be measured by peeling off the film at the time of measurement.
x: Detachment of the sample occurred before measurement, and adhesion could not be evaluated.

(Production of water-based adhesive)
A water-based adhesive was obtained by adding 3 parts by mass of a polyvinyl alcohol resin to 100 parts by mass of water and stirring and mixing.

<Example 1>
(Preparation of 1/4 wavelength retardation layer 1)
Rubbed orientation on a substrate film (first substrate film) made of polyethylene terephthalate resin (PET) film (thickness 100 μm, temperature 40° C., moisture permeability 13 g/m ² 24 hr at relative humidity 90% RH) A composition for forming a liquid crystal layer containing a rod-shaped nematic polymerizable liquid crystal compound (liquid crystal monomer) is applied to a film (thickness 1 μm), and solidified by irradiation with ultraviolet rays while maintaining refractive index anisotropy. On the alignment film of the substrate, a 1 μm-thick polymerizable liquid crystal compound cured layer 1 having reverse wavelength dispersion properties of 1/4 wavelength retardation layer 1 was formed. The reverse wavelength dispersion 1/4 wavelength retardation layer 1 had a light transmittance of 1% at a wavelength of 380 nm, and a water contact angle of 58° after corona treatment.

(Preparation of positive C plate)
A vertical alignment film is formed on one side of a base film (second base film) made of a polyethylene terephthalate resin (PET) film (thickness: 38 μm, temperature: 40° C., moisture permeability: 16 g/m ² 24 hr at relative humidity: 90% RH). A vertical alignment film was prepared by applying the composition for film to a film thickness of 3 μm and irradiating ultraviolet rays of 200 mJ/cm ² . A composition for forming a positive C plate containing a polymerizable liquid crystal compound is applied onto the vertical alignment film, and after drying, the coating film is irradiated with ultraviolet (UV) rays to polymerize the polymerizable liquid crystal compound to form a polymerizable liquid crystal. A positive C plate was obtained by forming a cured layer of the compound. The cured layer had a light transmittance of 85% at a wavelength of 380 nm and a water contact angle of 63° after corona treatment.

(Preparation of laminate)
Corona treatment was applied to the cured layer-side surfaces of the quarter-wave retardation layer 1 and the positive C plate. A coating film of a water-based adhesive was formed on the quarter-wave retardation layer 1 so that the thickness of the water-based adhesive layer after drying was 0.1 μm. After that, a release film [triacetyl cellulose resin (TAC) film subjected to release treatment, thickness 25 μm] was laminated on the water-based adhesive coating film, and dried in an air atmosphere at a temperature of 80° C. for 5 minutes. After that, the release film was peeled off to obtain a water-based adhesive layer with a thickness of 0.1 μm.
After subjecting the water-based adhesive layer to corona treatment at 28 kJ/m ² , a positive C plate was attached, and the PET film/orientation film/1/4 wavelength retardation layer 1/water-based adhesive layer/positive C plate/ A laminate having a layer structure of vertical alignment film/PET film was obtained. A curing step was performed by heating the obtained laminate in an air atmosphere at a temperature of 80° C. for 10 minutes. Table 1 shows the results.

<Example 2>
Example 1 except that a triacetyl cellulose resin (TAC) film (thickness 40 μm, temperature 40° C., relative humidity 90% RH and moisture permeability 950 g/m ² 24 hr) was used as the first base film. In the same manner as in Example 1, a laminate having a layer structure of TAC film/alignment film/1/4 wavelength retardation layer 1/aqueous adhesive layer/positive C plate/vertical alignment film/PET film was obtained. Table 1 shows the results.

<Comparative Example 1>
A laminate was produced in the same manner as in Example 1, except that the water-based adhesive layer was not subjected to corona treatment. Table 1 shows the results. The adhesion was evaluated as x, indicating that the positive C plate and the water-based adhesive layer were not bonded.

<Comparative Example 2>
(Preparation of 1/2 wavelength retardation layer)
An orientation film was formed on a base film (first base film) made of a triacetyl cellulose resin (TAC) film (thickness 40 μm, temperature 40° C., moisture permeability 950 g/m ² 24 hr at relative humidity 90% RH). Orientation treatment was performed by applying and drying the forming composition. Next, on the alignment film, a composition for forming a liquid crystal layer containing a nematic polymerizable liquid crystal compound is applied, and heat and UV irradiation are applied to fix the alignment of the polymerizable liquid crystal compound, whereby the alignment film on the substrate is Then, a 1/2 wavelength retardation layer was formed as a cured layer of a polymerizable liquid crystal compound having a thickness of 2 μm. The light transmittance of the half-wave retardation layer at a wavelength of 380 nm was 85%, and the contact angle with water was 59°.

(Preparation of 1/4 wavelength retardation layer 2)
A substrate film made of a triacetyl cellulose resin (TAC) film (thickness 40 μm, temperature 40° C., moisture permeability 950 g / m ² · 24 hr at relative humidity 90% RH) A composition for forming a liquid crystal layer containing a rod-shaped nematic polymerizable liquid crystal compound (liquid crystal monomer) is applied to an alignment film (thickness 1 μm), and solidified by irradiation with ultraviolet rays while maintaining refractive index anisotropy. A positive wavelength dispersion quarter-wave retardation layer 2 as a cured layer of a polymerizable liquid crystal compound having a thickness of 1 μm was formed on the alignment film of the substrate. 2 had a light transmittance of 85% at a wavelength of 380 nm and a water contact angle of 76°.

(Preparation of laminate)
In Example 1, the 1/4 wavelength retardation layer obtained above was used instead of the 1/4 wavelength retardation layer 1, and the 1/4 wavelength retardation layer obtained above was used instead of the positive C plate. In the same manner as in Example 1 except that the retardation layer 2 was used, TAC film/alignment film/half wavelength retardation layer/water-based adhesive layer/quarter wavelength retardation layer 2/alignment film/TAC film A laminate having a layer structure of was obtained. Table 1 shows the results.

10, 20, 30, 40 laminate 11, 41 first retardation layer 13, 42 second retardation layer 12, 46 water-based adhesive layer 21 first base film 22 second Base film 31 Linear polarizing plate 32 Bonding layer 33 Polarizer 34 Protective film 45 Water-based adhesive coating film 47 Release film.

Claims (7)

The first retardation layer and the second retardation layer are laminated via a water-based adhesive layer,
The first retardation layer and the second retardation layer comprise a cured layer of a polymerizable liquid crystal compound,
At least one of the first retardation layer and the second retardation layer has a light transmittance of 10% or less at a wavelength of 380 nm. Either one of the first retardation layer and the second retardation layer is a reverse wavelength dispersion 1/4 wavelength retardation layer, and the other is a positive C-plate, according to claim 1 laminate. Further comprising a first base film and a second base film,
The first base film is arranged on the side opposite to the water-based adhesive layer side of the first retardation layer,
The laminate according to claim 1 or 2, wherein the second base film is arranged on the side opposite to the water-based adhesive layer side of the second retardation layer. 4. The laminate according to claim 3, wherein each of the first base film and the second base film has a water vapor permeability of 200 g/m ² ·24 hr or less at a temperature of 40° C. and a relative humidity of 90% RH. A first step of forming a coating film of a water-based adhesive on the first retardation layer;
a second step of drying the coating film of the water-based adhesive to form a water-based adhesive layer;
After applying a surface activation treatment to the surface of the aqueous adhesive layer opposite to the first retardation layer side, the first retardation layer and the second retardation layer are attached to the aqueous adhesive layer. a third step of laminating via an agent layer;
in this order,
A method for producing a laminate, wherein at least one of the first retardation layer and the second retardation layer has a light transmittance of 10% or less at a wavelength of 380 nm. The method for manufacturing a laminate according to claim 5, further comprising a curing step of heating the laminate after the third step. The second step is
A step of laminating a release film on the coating film of the water-based adhesive;
After drying the coating film of the water-based adhesive layer, peeling the release film;
The method for manufacturing a laminate according to claim 5 or 6, further comprising:

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