KR20230064564A - Laminate and method for manufacturing the same - Google Patents

Abstract

[Problem] A laminate in which two retardation layers are bonded together via a water-based adhesive, even when at least one of the light transmittances at a wavelength of 380 nm of the two retardation layers constituting the laminate is 10% or less, phase difference To provide a laminate having good interlayer adhesion.
[Solution] The first retardation layer and the second retardation layer are laminated through a water-based adhesive layer, the first retardation layer and the second retardation layer include a cured layer of a polymerizable liquid crystal compound, and the first retardation layer and a light transmittance of at least one of the second retardation layers at a wavelength of 380 nm is 10% or less.

Description

Laminate and its manufacturing method {LAMINATE AND METHOD FOR MANUFACTURING THE SAME}

The present invention relates to a laminate and also to a method for manufacturing the laminate.

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

[Patent Document 1] Japanese Unexamined Patent Publication No. 2018-017996

When the retardation layers are bonded to each other through an active energy ray-curable adhesive, if the light transmittance of any one of the retardation layers is low, the amount of light of the active energy ray irradiated to the adhesive layer is reduced. As a result, there was a case where the adhesion between the retardation layers could not be sufficiently obtained.

In addition, when using an adhesive that cures with light in the visible light wavelength region with high light transmittance in the retardation layer, in order to prevent the adhesive from unintentionally curing, it is necessary to respond in terms of production equipment, making it difficult to apply. .

In addition, when thin film retardation layers are bonded to each other through an active energy ray curing type adhesive, the thickness of the adhesive layer tends to be thicker compared to the case where they are bonded through a water-based adhesive, and as the adhesive cures and shrinks, wrinkles There was a case where the appearance quality of the laminate was deteriorated due to the occurrence of.

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

The present invention provides the following laminate and a method for manufacturing the laminate.

[1] The first retardation layer and the second retardation layer are bonded through a water-based adhesive layer,

The first retardation layer and the second retardation layer include a cured layer of a polymerizable liquid crystal compound,

A laminate wherein at least either 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] The laminate according to [1], wherein one of the first retardation layer and the second retardation layer is a 1/4 wavelength retardation layer with reverse wavelength dispersion, and the other is a positive C plate.

[3] further comprising a first base film and a second base film,

The first base film is disposed on a side opposite to the side of the water-based adhesive layer in the first retardation layer,

The laminate according to [1] or [2], wherein the second base film is disposed on a side opposite to the water-based adhesive layer in the second retardation layer.

[4] The laminate according to [3], wherein both the first base film and the second base film have water vapor transmission rates of 200 g/m ² ·24 hr or less at a temperature of 40°C and a relative humidity of 90% RH.

[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;

A third step of bonding the first retardation layer and the second retardation layer through the water-based adhesive layer after surface activation treatment is performed on the surface of the water-based adhesive layer on the opposite side to the first retardation layer side in this order equipped with,

The method of manufacturing a laminate, wherein at least either one of the first retardation layer and the second retardation layer has a light transmittance at a wavelength of 380 nm of 10% or less.

[6] The method for producing a laminate according to [5], further comprising a curing step of heating the laminate after the third step.

[7] The second step,

a step of laminating a release film on the coating film of the water-based adhesive;

The method for producing a laminate according to [5] or [6], further comprising a step of peeling the release film after drying the coating film of the water-based adhesive layer.

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

1 is a schematic cross-sectional view showing an example of the layer configuration of a laminate of the present invention.
Fig. 2 is a schematic cross-sectional view showing an example of another layer configuration of the laminate of the present invention.
3 is a schematic cross-sectional view showing an example of the layer structure of a polarizing plate provided with a laminate of the present invention.
4 is a schematic cross-sectional view showing an example of a method for manufacturing a laminate of the present invention.

EMBODIMENT OF THE INVENTION Hereinafter, although embodiment of this invention is described referring drawings, this invention is not limited to the following embodiment. In all of the following drawings, the scales of each component are appropriately adjusted to make it easier to understand, and the scale of each component shown in the drawings does not necessarily coincide with the scale of the actual component.

<Laminate>

In the laminate of the present embodiment, the first retardation layer and the second retardation layer are bonded through a water-based adhesive layer, the first retardation layer and the second retardation layer include a cured layer of a polymerizable liquid crystal compound, At least either one of the light transmittance at a wavelength of 380 nm of the retardation layer and the second retardation layer is 10% or less. In this specification, the first retardation layer and the second retardation layer may be referred to as a retardation layer as a general term. In addition, as a generic term for the first base film and the second base film to be described later, it may be referred to as a base film. In addition, "sticking together" means a state in which two layers are in contact with each other and are adhered to each other.

The laminate of this embodiment will be described with reference to FIG. 1 . The 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 layered product 10 may have other layers, such as a first base film, a second base film, an alignment film, and the like described later.

The light transmittance at a wavelength of 380 nm of the first retardation layer 11 and the second retardation layer 13 is at least 10% or less. When a water-based adhesive is used for adhesion between phase difference layers, thermal deterioration of the phase difference layer may occur due to heating for removing water from the water-based adhesive. Therefore, conventionally, an active energy curing type adhesive has been used for adhesion between phase difference layers. However, when at least one of the light transmittances of the two retardation layers at a wavelength of 380 nm is 10% or less, the active energy curing type adhesive is not sufficiently cured, and the adhesion between the retardation layers is insufficient. There was a case. The laminate of the present embodiment tends to have excellent adhesion between the layers, even though at least either one of the light transmittances at a wavelength of 380 nm of the two retardation layers is 10% or less. In addition, the laminate 10 of the present embodiment can have superior appearance quality compared to the case where an active energy ray curable adhesive is used.

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 the first retardation layer 11 or the second retardation layer 13 may be, for example, 0% or more, and is preferably 3% or more. The light transmittance of the first phase difference layer 11 and the second phase difference layer 13 at a wavelength of 380 nm may be, for example, 10% or less, 5% or less, 0% or more, or 3% or more. good night. The first retardation layer 11 and the second retardation layer 13 may have the same or different light transmittances 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 section of Examples to be described later.

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, and more preferably 2 N/25 mm or more. N/25 mm or more. In the laminate 10, the adhesion 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 section of Examples to be described later.

In the laminate 10, the adhesive strength 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, and more preferably 2 N/25 mm or more. N/25 mm or more. In the laminate 10, the adhesion 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 section of Examples to be described later.

(phase difference layer)

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

The retardation layer may be a 1/2 wavelength retardation layer, a 1/4 wavelength retardation layer or a positive C plate. When the retardation layer is a 1/4 wavelength 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.

Reverse wavelength dispersion is an optical characteristic in which the in-plane retardation value for liquid crystal orientation at a shorter wavelength is smaller than the in-plane retardation value for liquid crystal orientation at a longer wavelength, and preferably the optical film satisfies the following formulas (i) and formulas (ii). will be. Here, Re(λ) represents an in-plane retardation value for light having a wavelength of λ nm.

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 may be a 1/4 wavelength retardation layer having reverse wavelength dispersion, and the other may be a positive C plate. For example, each of the first retardation layer 11 and the second retardation layer 13 is a 1/4 wavelength retardation layer and a positive C plate having reverse wavelength dispersion.

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

When the refractive index in the film in-plane slow axis direction (the direction in which the in-plane refractive index is greatest) is nx, the refractive index in the direction orthogonal to the in-plane slow axis and the in-plane direction is ny, and the refractive index in the thickness direction is nz, positive C plate satisfies the relationship of the following equation.

nz>nx≒ny

Here, "≒" includes not only the case where both are completely equal, but also the case where both are substantially equal.

Examples of the polymerizable liquid crystal compound include a rod-shaped polymerizable liquid crystal compound and a disk-shaped polymerizable liquid crystal compound, either one of which may be used, or a mixture containing both of these may be used. When the rod-shaped polymerizable liquid crystal compound is horizontally aligned or vertically aligned with respect to the substrate layer, the optical axis of the polymerizable liquid crystal compound coincides with the major axis direction of the polymerizable liquid crystal compound. When the disk-shaped polymerizable liquid crystal compound is aligned, the optical axis of the polymerizable liquid crystal compound exists in a direction orthogonal to the disk plane of the polymerizable liquid crystal compound. As the rod-shaped polymerizable liquid crystal compound, those described in, for example, Japanese Patent Publication No. 11-513019 (Claim 1 and the like) can be suitably used. As the discoid polymerizable liquid crystal compound, those disclosed in Japanese Patent Laid-Open No. 2007-108732 (paragraphs [0020] to [0067], etc.) and Japanese Patent Laid-Open No. 2010-244038 (paragraphs [0013] to [0108], etc.) are suitable. can be used appropriately.

In order for the cured layer formed by polymerizing the polymerizable liquid crystal compound to express an in-plane retardation, the polymerizable liquid crystal compound may be oriented in an appropriate direction. When the polymerizable liquid crystal compound is rod-shaped, in-plane retardation is developed by orienting the optical axis of the polymerizable liquid crystal compound horizontally with respect to the plane of the substrate film described later, and in this case, the optical axis direction and the slow axis direction coincide. When the polymerizable liquid crystal compound is disk-shaped, in-plane retardation is developed by orienting the optical axis of the polymerizable liquid crystal compound horizontally with respect to the plane of the substrate film described later, and in this case, the optical axis and the slow axis are orthogonal. The alignment state of the polymerizable liquid crystal compound can be adjusted by a combination of the alignment layer and the polymerizable liquid crystal compound.

A polymerizable liquid crystal compound is a compound having at least one polymerizable group and also having liquid crystallinity. When two or more kinds of polymerizable liquid crystal compounds are used together, it is preferable that at least one kind has two or more polymerizable groups in the molecule. A polymerizable group means a group involved in a polymerization reaction, and a photopolymerizable group is preferred. Here, the photopolymerizable group means a group that can participate in a polymerization reaction by an active radical or an acid generated from a photopolymerization initiator described later. Examples of the polymerizable group include a vinyl group, a vinyloxy group, a 1-chlorovinyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, a methacryloyloxy group, an oxiranyl group, an oxetanyl group, a styryl group, and an allyl group. and the like. Especially, an acryloyloxy group, a methacryloyloxy group, a vinyloxy group, an oxiranyl group, and an oxetanyl group are preferable, and an acryloyloxy group is more preferable. The liquid crystalline property of the polymerizable liquid crystal compound may be either a thermotropic liquid crystal or a lyotropic liquid crystal, and if the thermotropic liquid crystal is classified according to the degree of order, it may be a nematic liquid crystal or a smectic liquid crystal.

The retardation layer may contain an alignment film. The alignment film has an alignment regulating force for orienting 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 the molecular axis of the polymerizable liquid crystal compound is aligned in the substrate layer. It may be an inclined alignment film that is inclined to align with respect to. When the retardation layer includes two or more alignment films, the alignment films may be the same or different.

As the alignment film, it is preferable to have resistance to solvents that do not dissolve by application of a composition for forming a liquid crystal layer containing a polymerizable liquid crystal compound, and to have heat resistance to removal of the solvent or heat treatment for alignment of the polymerizable liquid crystal compound. Examples of the alignment film include an alignment polymer layer formed of an alignment polymer, an optical alignment polymer layer formed of an optical alignment polymer, and a groove alignment film having a concavo-convex pattern or a plurality of grooves on the surface of the layer.

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, 2 μm or more, and preferably 10 μm or less. , may be 8 μm or less, and 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 base film described later, 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 base film to be described later.

The water contact angle of the first retardation layer 11 and the second retardation layer 13 may be, for example, 75° or less, and is preferably 70° or less from the viewpoint of enhancing adhesion, and more preferably It is less than 65 degrees. The logarithmic contact angle of the surface of the cured layer can be measured according to the method described in the section of Examples to be described later.

(water-based adhesive layer)

The water-based adhesive layer 12 may be disposed 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 may be multilayered.

The water-based adhesive layer 12 may be formed of a water-based adhesive. Examples of water-based adhesives include adhesives made of a polyvinyl alcohol-based resin aqueous solution, water-based two-component urethane emulsion adhesives, and the like. Among them, a water-based adhesive composed of a polyvinyl alcohol-based resin aqueous solution is preferably used. Examples of the polyvinyl alcohol-based resin include vinyl alcohol homopolymers obtained by saponifying polyvinyl acetate, which is a homopolymer of vinyl acetate, and polyvinyl alcohol-based copolymers obtained by saponifying vinyl acetate and copolymers of other monomers copolymerizable therewith. Combinations or modified polyvinyl alcohol-based polymers obtained by partially modifying their hydroxyl groups can be used. The water-based adhesive may contain a crosslinking agent such as an aldehyde compound (eg glyoxal), an epoxy compound, a melamine compound, a methylol compound, an isocyanate compound, an amine compound, or a polyvalent metal salt.

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

The water-based adhesive layer 12 may be formed by laminating the first retardation layer 11 and the second retardation layer 13 using a water-based adhesive and then performing a drying process to remove water contained in the water-based adhesive. there is. When the water-based adhesive is dried, the water-based adhesive layer 12 is formed, and the first retardation layer 11 and the second retardation layer 13 are bonded.

As for the thickness of the water-based adhesive layer 12, 0.1 micrometer or more and 1 micrometer or less are preferable.

(substrate film)

The base film may have a function of supporting the cured layer and the alignment layer. As the base film, a light-transmitting (preferably optically transparent) thermoplastic resin, for example, polyolefin-based resins such as chain polyolefin-based resins (such as polypropylene-based resins) and cyclic polyolefin-based resins (such as norbornene-based resins); cellulosic resins such as triacetyl cellulose and diacetyl cellulose; polyester-based resins such as polyethylene terephthalate and polybutylene terephthalate; polycarbonate-based resin; (meth)acrylic resins such as methyl methacrylate resins; polystyrene-based resin; polyvinyl chloride-based resins; Acrylonitrile·butadiene·styrene type resin; Acrylonitrile styrene type resin; polyvinyl acetate-based resin; polyvinylidene chloride-based resins; polyamide-based resin; polyacetal-based resins; Modified polyphenylene ether type resin; polysulfone-based resins; polyethersulfone-based resins; polyarylate-based resins; polyamideimide-based resins; It may be a film made of polyimide-based resin or the like.

As the chain polyolefin-based resin, polyethylene resin (a polyethylene resin which is a homopolymer of ethylene or a copolymer mainly composed of ethylene), a polypropylene resin (a polypropylene resin which is a homopolymer of propylene or a copolymer mainly composed of propylene), In addition to homopolymers of the same chain olefins, copolymers composed of two or more types of chain olefins are exemplified.

Cyclic polyolefin-based resin is a generic term for resins polymerized using cyclic olefins as polymerized units, such as Japanese Unexamined Patent Publication No. 1-240517, Japanese Unexamined Patent Publication No. 3-14882, and Japanese Unexamined Patent Publication No. 3-122137 The resin described in the etc. is mentioned. Specific examples of cyclic polyolefin 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 random copolymers), and unsaturated Graft polymers modified with carboxylic acids or derivatives thereof, and hydrides thereof. Among them, a norbornene-based resin using a norbornene-based monomer such as norbornene or a polycyclic norbornene-based monomer as a cyclic olefin is preferably used.

Polyester-based resins are resins having an ester bond, excluding the following cellulose ester-based resins, and are generally composed of a polycondensate of a polyhydric carboxylic acid or a derivative thereof and a polyhydric alcohol. As the polyhydric carboxylic acid or a derivative thereof, a divalent dicarboxylic acid or a derivative thereof can be used, and examples thereof include terephthalic acid, isophthalic acid, dimethyl terephthalate, and dimethyl naphthalene dicarboxylic acid. As the polyhydric alcohol, divalent diols can be used, and examples thereof include ethylene glycol, propanediol, butanediol, neopentyl glycol, and cyclohexanedimethanol. As a representative example of the polyester-based resin, polyethylene terephthalate, which is a polycondensate of terephthalic acid and ethylene glycol, is exemplified.

A (meth)acrylic resin is a resin that uses a compound having a (meth)acryloyl group as a main constituent monomer. Specific examples of the (meth)acrylic resin include 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 copolymers (such as MS resin); and copolymers of methyl methacrylate and a compound having an alicyclic hydrocarbon group (for example, 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 poly(meth)acrylate is used, more preferably methyl methacrylate as a main component (50% by mass or more and 100% by mass or less). , preferably 70% by mass or more and 100% by mass or less) of methyl methacrylate-based resin is used.

Cellulose ester-type resin is an ester of cellulose and a fatty acid. Specific examples of the cellulose ester-based resin include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. Moreover, those copolymers and those in which a part of hydroxyl groups were modified with other substituents are also exemplified. Among these, cellulose triacetate (triacetyl cellulose) is particularly preferable.

A polycarbonate-based resin is an engineering plastic composed of a polymer in which monomer units are bonded through a carbonate group.

The thickness of the base film is not particularly limited, but is generally preferably 1 μm or more and 300 μm or less, and more preferably 20 μm or more and 200 μm or less, from the viewpoint of workability such as strength and handleability. The base film may be inserted into the circular polarizing plate together with the retardation layer, or the retardation layer alone or the retardation layer and the alignment film may be inserted into the circular polarizing plate after the base layer is peeled off.

The 1st base film and the 2nd base film may be comprised from the thermoplastic resin of the same type, and may be comprised from the thermoplastic resin of a different type. Further, the thicknesses may be the same or 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 transmittances of the first base film and the second base film at a wavelength of 380 nm may be the same or different. When the laminate includes the first base film and the second base film, the light transmittance of the first base film and the second base film at a wavelength of 380 nm may be, for example, 95% or less for both, preferably 90% for both. % or less, more preferably both are 85% or less.

The moisture permeability of the base 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. can The water vapor transmission rate of the base 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, and more preferably 50 g/m ² ·24 hr or more. When the laminate includes the first base film and the second base film, 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 may be the same or different. The moisture permeability at a temperature of 40° C. and a relative humidity of 90% RH can be measured according to the method described in the section of Examples to be described later.

The layer configuration of the laminate with the base film is shown in FIG. 2 . 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. are provided in this order. The 1st base film 21 is arrange|positioned on the side opposite to the water-based adhesive layer 12 side in the 1st retardation layer 11. The 2nd base film 22 is arrange|positioned on the side opposite to the water-based adhesive layer 12 side in the 2nd retardation layer 13.

(use of laminated body)

The laminate of this embodiment can be used for a polarizing plate. The polarizing plate may be a circular polarizing plate in which the laminate 10 and the linear polarizing plate are laminated.

3 is a schematic cross-sectional view showing an example of the layer structure of a polarizing plate. In the polarizing plate 30 shown in FIG. 3 , the linear polarizing plate 31 and the laminate 10 are bonded together via a bonding layer 32 . The linear polarizing plate 31 includes a polarizer (linear polarizer) 33 and a protective film 34 . The protective film 34 is adhered to the polarizer 33 via an adhesive layer (not shown). The laminate 10 is disposed on the side of the protective film 34 of the linear polarizing plate 31 .

(polarizer)

Examples of the polarizer 33 include a stretched film or a stretched layer in which a dichroic dye is adsorbed, a polarizer layer obtained by applying and curing a dichroic dye, and the like. A polarizer layer formed by applying and curing a dichroic dye is preferable because there is no restriction in the bending direction compared to a stretched film or a stretched layer in which a dye having absorption anisotropy is adsorbed.

As the dichroic dye, iodine and dichroic organic dye are specifically used. Examples of dichroic organic dyes include azo dyes and the like. Azo dyes include, for example, C.I. Dichromatic 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 adsorbed with dichroic dye)

The stretched film to which the dichroic dye is adsorbed is usually a step of uniaxially stretching the polyvinyl alcohol-based resin film, a step of adsorbing the dichroic dye by dyeing the polyvinyl alcohol-based resin film with the dichroic dye, and adsorption of the dichroic dye. It can be manufactured through a process of treating the polyvinyl alcohol-based resin film with an aqueous solution of boric acid and a process of washing with water after treatment with an aqueous solution of boric acid.

The stretched film to which the dichroic dye is adsorbed may have a thickness of, for example, 2 μm or more and 40 μm or less, 5 μm or more, 20 μm or less, more preferably 15 μm or less, and more preferably 10 μm or less.

The polyvinyl alcohol-based resin is obtained by saponifying a polyvinyl acetate-based resin. As polyvinyl acetate-type resin, the copolymer of vinyl acetate and the other monomer copolymerizable with it other than polyvinyl acetate which is a homopolymer of vinyl acetate is used. Examples of other monomers copolymerizable 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, and for example, polyvinyl formal and polyvinyl acetal modified with aldehydes can also be used. The degree of polymerization of the polyvinyl alcohol-based 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 a step of applying a coating solution containing the above polyvinyl alcohol-based resin onto a base film, a step of uniaxially stretching the obtained laminated film, and a polyvinyl alcohol-based uniaxially stretched laminated film. A step of dyeing the resin layer with a dichroic dye to adsorb the dichroic dye to form a polarizer layer, a step of treating the film adsorbed with the dichroic dye with an aqueous solution of boric acid, and a step of washing with water after treatment with the aqueous solution of boric acid. can

If necessary, the base film may be peeled off from the stretched layer in 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 description of the retardation layer described above.

(Polarizer layer obtained by applying and curing a dichroic dye)

As a polarizer layer formed by applying and curing a dichroic dye, a layer obtained by applying a composition containing a polymerizable dichromatic dye having liquid crystallinity or a composition containing a polymerizable liquid crystal compound and a dichroic dye to a base film and curing, and the like A polarizer layer containing a cured product of a polymerizable liquid crystal compound of The base film may have an alignment film formed on one surface. The polarizer 33 is preferably a layer comprising an alignment film and a cured product of a composition containing a polymerizable liquid crystal compound and one or a plurality of azo dyes, 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 inserted into the polarizing plate 30 together with the base film, or may be inserted into the polarizing plate 30 by peeling off the base film from the polarizer layer obtained by applying a dichroic dye and curing the base film. The material and thickness of the base film may be the same as the material and thickness of the base film described in the description of the retardation layer described above. A hard coat layer (HC layer) may be formed on at least one surface of the base film as a protective layer described later.

The thickness of the polarizer layer obtained by applying 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 may have a function of protecting the surface of the polarizer 33 . In FIG. 3 , the protective film 34 is disposed on one side of the polarizer 33 , but the protective film may be disposed on both sides of the polarizer 33 .

As the protective film 34, a thermoplastic resin film constituting the base film described in the description of the retardation layer described above 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, still more preferably, from the viewpoint of thinning. It is 30 μm or less, and is usually 1 μm or more, and may be, for example, 5 μm or more or 20 μm or more.

The protective film 34 may be adhered to the polarizer 33 through a bonding layer described later. As the bonding layer for bonding the thermoplastic resin film to the polarizer 33, it is preferably an adhesive layer.

[bonding layer]

The bonding layer 32 may be a pressure-sensitive adhesive layer made of a pressure-sensitive adhesive or an adhesive layer made of an adhesive. An adhesive is also called a pressure-sensitive adhesive. In this specification, "adhesive" refers to adhesives other than adhesives (pressure-sensitive adhesives), and is clearly distinguished from adhesives. The pressure-sensitive adhesive layer may be one layer or may consist of two or more layers, but is preferably one layer. The pressure-sensitive adhesive layer may be formed of a pressure-sensitive adhesive composition.

The pressure-sensitive adhesive layer may be composed of a pressure-sensitive adhesive composition containing a resin such as (meth)acrylic, rubber, urethane, ester, silicone, or polyvinyl ether as a main component. Among them, a pressure-sensitive adhesive composition comprising a (meth)acrylic resin having excellent transparency, weather resistance, heat resistance, and the like as a base polymer is suitable. The pressure-sensitive adhesive composition may be of an active energy ray curing type or a heat curing type.

Examples of the (meth)acrylic resin (base polymer) used in the pressure-sensitive adhesive composition include (meth)acrylic acid such as butyl (meth)acrylate, ethyl (meth)acrylate, isooctyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. A polymer or copolymer having one or two or more esters as monomers is suitably used. It is preferable to copolymerize a polar monomer into the base polymer. Examples of the polar monomer include (meth)acrylic acid, 2-hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate, (meth)acrylamide, N,N-dimethylaminoethyl (meth)acrylate, and glycidyl. and monomers having a carboxyl group, a hydroxyl group, an amide group, an amino group, an epoxy group and the like, such as (meth)acrylate.

The pressure-sensitive adhesive composition may contain only the base polymer, but usually further contains a crosslinking agent. As a crosslinking agent, it is a divalent or more metal ion, and forms a carboxylic acid metal salt between carboxyl groups; It is a polyamine compound, and forms an amide bond between carboxyl groups; It is a polyepoxy compound or a polyol, and forms an ester bond between carboxyl groups; It is a polyisocyanate compound, and what forms an amide bond between carboxyl groups is illustrated. Among them, polyisocyanate compounds are preferred.

An active energy ray-curable pressure-sensitive adhesive composition has a property of being cured by being irradiated with active energy rays such as ultraviolet rays or electron beams, has adhesiveness even before active energy ray irradiation, and can adhere to an adherend such as a film, and can be adhered to an adherend such as a film, and is irradiated with active energy rays It is a pressure-sensitive adhesive composition having a property that can be cured and adjusted by adhesion. The active energy ray-curable pressure-sensitive adhesive composition is preferably an ultraviolet curable type. 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 crosslinking agent. Furthermore, a photoinitiator, a photosensitizer, etc. can also be contained as needed.

The pressure-sensitive adhesive composition includes fine particles for imparting light scattering properties, beads (resin beads, glass beads, etc.), glass fibers, resins other than the base polymer, tackifiers, fillers (metal powder or other inorganic powders, etc.), antioxidants, Additives such as ultraviolet absorbers, dyes, pigments, colorants, antifoaming agents, corrosion inhibitors, antistatic agents, and photopolymerization initiators may be included.

The pressure-sensitive adhesive layer can be formed by applying a diluted organic solvent of the pressure-sensitive adhesive composition on a substrate and drying it. In the case of using an active energy ray-curable pressure-sensitive adhesive composition, a cured product having a desired degree of curing can be obtained by irradiating the formed pressure-sensitive adhesive layer with active energy rays.

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 constituting the bonding layer 32, for example, it can be formed by combining one or two or more types of water-based adhesives, active energy ray curable adhesives, pressure-sensitive adhesives, and the like. As the water-based adhesive, those mentioned in the description of the above-mentioned water-based adhesive layer can be used. The active energy ray-curable adhesive is an adhesive that is cured by irradiating active energy rays such as ultraviolet rays, and includes, for example, one containing a polymerizable compound and a photopolymerization initiator, one containing a photoreactive resin, a binder resin and a photoreactive crosslinking agent. to do, etc. Examples of the polymerizable compound include photopolymerizable monomers such as photocurable epoxy monomers, photocurable acrylic monomers, and photocurable urethane monomers, oligomers derived from these monomers, and the like. Examples of the photopolymerization initiator include materials that generate active species such as neutral radicals, anion radicals, and cation radicals by irradiation with active energy rays such as ultraviolet rays.

When using a pressure-sensitive adhesive layer as the bonding layer 32, it 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, preferably 10 μm or less, and may be 5 μm or less.

The polarizing plate 30 can be used for 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. can be heard The polarizing plate 30 may be disposed on the viewing side (front side) of the image display device or may be disposed on the rear side.

<Method for manufacturing laminated body>

The method for manufacturing a laminate of the present embodiment includes a first step of forming a coating film of the 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, and a water-based adhesive layer. A third step of bonding the first retardation layer and the second retardation layer together through the water-based adhesive layer after surface activation treatment is applied to the surface on the opposite side to the first retardation layer side of the first retardation layer in this order, and light transmittance of the second retardation layer at a wavelength of 380 nm, at least either of which is 10% or less. Regarding 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 above-described laminate 10, respectively. description applies.

At least either of the light transmittances at a wavelength of 380 nm of the first retardation layer and the second retardation layer is 10% or less. When a water-based adhesive is used for bonding the retardation layers, thermal deterioration of the retardation layer may occur due to heating to remove moisture from the water-based adhesive. Therefore, conventionally, an active energy curing type adhesive has been used for adhesion between phase difference layers. However, when at least either one of the light transmittance at a wavelength of 380 nm of the retardation layer is 10% or less, the active energy curable adhesive is not sufficiently cured, and the adhesion between the retardation layers may be insufficient. According to the method for producing a laminate of the present invention, it is possible to manufacture a laminate excellent in adhesion between layers even when the light transmittance of any one of the retardation layers at a wavelength of 380 nm is 10% or less. Further, according to the production method of the present invention, it is easy to obtain a laminate having excellent appearance quality compared to the case where an active energy ray curable adhesive is used.

The manufacturing method of the laminated body of this embodiment is demonstrated, referring FIG. In the first step, a coating film 45 of a water-based adhesive is formed on the first retardation layer 41 (Fig. 4(a)). A method of applying the water-based adhesive onto the first retardation layer 41 may be, for example, a conventionally known method. In the manufacturing method of the laminate of this embodiment, the retardation layer can be manufactured according to the method described above, and the retardation layer may contain at least any one of an alignment film and a base film, or the base film may be removed. Although not shown, when the first retardation layer 41 includes a base film, a coating film 45 of a water-based adhesive is formed on the surface of the first retardation layer 41 side. Although not shown, a surface activation treatment may be applied to the surface of the first retardation layer 41 from the viewpoint of making it easier to improve adhesion.

In the second step, the coating film 45 of the water-based adhesive is dried to form the water-based adhesive layer 46 (FIG. 4(b)). The second step is a step of laminating the release film 47 on the coating film 45 of the water-based adhesive (Fig. 4 (b1)), and drying the release film 47 and the coating film 45 of the water-based adhesive to dry the water-based adhesive. After forming the adhesive bond layer 46, the process of peeling [FIG. 4(b2)] can be provided further. As a method of drying the coating film 45 of the water-based adhesive, for example, drying can be carried out by a conventionally known method. The drying temperature of the coating film 45 of the water-based adhesive may be, for example, 20°C or higher and 90°C or lower. The drying time of the coating film 45 of the water-based adhesive 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, when drying the water-based adhesive, from the viewpoint of sufficiently removing moisture from the adhesive, the plastic film used preferably has a water vapor transmission rate of 200 g/m ² ·24 hr or more. As a plastic film, a triacetyl cellulose-type resin (TAC) film etc. are mentioned, for example. In addition, the peeling layer can be formed of, for example, a composition for forming a peeling layer. The main component (resin) constituting the composition for forming a release layer is not particularly limited, but includes silicone resins, alkyd resins, acrylic resins and long-chain alkyl resins.

In the third step, after surface activation treatment is applied to the surface of the water-based adhesive layer 46 on the opposite side to the first retardation layer 41 side, the first retardation layer 41 and the second retardation layer 42 are formed. The laminate 40 is obtained by pasting through the water-based adhesive layer 46 (FIG. 4(c)). By performing the surface activation treatment, it is possible to easily improve the adhesion between the water-based adhesive layer and the second retardation layer 42 . 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 a bonding surface with the water-based adhesive layer 46 . Examples of the surface activation treatment include dry treatment such as corona treatment, plasma treatment, electric discharge treatment (glow discharge treatment, etc.), ozone treatment, UV ozone treatment, and ionizing ray treatment (ultraviolet treatment, electron beam treatment, etc.). These surface activation treatments may be performed alone or in combination of two or more. Among them, corona treatment is preferable. Corona treatment can be performed with 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, surface activation treatment may also be applied to the bonded surface of the second retardation layer 42 to the water-based adhesive layer 46 from the viewpoint of making it easier to improve adhesion.

Although not shown, in the manufacturing method of the laminate of the present invention, in order to easily improve the adhesion between the adhesive layer 46 and the second retardation layer 42, after the third step, the laminate 40 is cured. A curing process may be further provided. In the curing step, the laminate may be heated. In the curing step, the temperature at which the laminate 40 is heated 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 is 75 ° C or more and 85 ° C or less. In the curing process, the time for curing the layered product 40 may be, for example, 1 minute or more and 2 hours or less.

In the laminate 40 obtained by the manufacturing method of the present embodiment, 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, and preferably 1.5 N/25 mm or more. 25 mm or more, more preferably 2 N/25 mm or more. In the laminate 40, the adhesion 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 section of Examples to be described later.

In the laminate 40 obtained by the manufacturing method of the present embodiment, the adhesive force between the water-based adhesive layer 46 and the second retardation layer 42 may be, for example, 1 N/25 mm or more, and preferably 1.5 N/25 mm or more. 25 mm or more, more preferably 2 N/25 mm or more. In the laminate 40, the adhesion 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 section of Examples to be described later.

Example

Hereinafter, the present invention will be described in more detail by examples. In the example, "%" and "part" are mass % and mass part unless otherwise specified.

(Measurement of light transmittance)

The retardation layer was cut into a size of 30 mm × 30 mm, and transmittance [%] was measured between wavelengths of 200 and 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 a temperature of 40 ° C., a relative humidity of 90% RH, and a measurement time of 24 hours. The measured water vapor transmission rate was defined as the moisture permeability [%] at a temperature of 40°C and a relative humidity of 90% RH.

(measurement of logarithmic contact angle)

The logarithmic contact angle after surface treatment under the same conditions as when producing the laminate is the logarithmic contact angle of the measuring object. That is, after performing corona treatment on the surfaces of the first retardation layer and the second retardation layer in Examples and Comparative Examples, a contact angle measurement (manufactured by Kyowa Gamemen Chemical Co., Ltd.) is performed so that the corona treated surface becomes the upper surface. , An image processing type contact angle meter "FACE CA-X type") was set horizontally, 1 µL of pure water was dropped at the measuring position, and the logarithmic contact angle was measured by the θ/2 method. The measurement position was set to a position of about 200 mm from the end side of one side of the width direction of the laminate for measurement.

(measurement of thickness)

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, polarizer, and 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. The retardation layer was exposed by peeling the first base film from the cut laminate. A triacetyl cellulose-based resin (TAC) film (thickness of 40 μm) was bonded to the surface of the retardation layer through an adhesive. Subsequently, the retardation layer was exposed by peeling off the second base film. A glass plate was bonded to the surface of the retardation layer through an adhesive. In this way, a measurement sample having a layer configuration of TAC film/pressure sensitive adhesive/phase difference layer/water-based adhesive layer/phase difference layer/pressure sensitive adhesive/glass plate was obtained. Adhesion was measured by measuring the force when peeling in the 180° direction while holding the TAC film of the measurement sample to the water-based adhesive layer using a precise universal tester "Autograph AGS-50NX" manufactured by Shimadzu Seisakusho Co., Ltd. . The measurement was performed under an environment of a temperature of 23±2° C. and a relative humidity of 50±5% at a peeling rate of 300 mm/min. It was set as the following evaluation criteria.

A: Adhesion was good, and the part of the layer held at the time of measurement was materially destroyed.

B: It was possible to measure the adhesion by peeling the film at the time of measurement.

C: Before the measurement, peeling of the sample occurred and adhesion could not be evaluated.

(Manufacture of water-based adhesive)

An aqueous adhesive was obtained by adding and mixing 3 parts by mass of polyvinyl alcohol-based resin with respect to 100 parts by mass of water and stirring.

<Example 1>

(Manufacture of 1/4 wavelength retardation layer 1)

A base film (first base film) made of a polyethylene terephthalate resin (PET) film (thickness: 100 μm, temperature: 40° C., moisture permeability at 90% RH: 13 g/m ² ·24 hr) was prepared. An alignment film (thickness of 1 μm) subjected to rubbing was formed on the base film. On the alignment film, a composition for forming a liquid crystal layer containing a rod-shaped nematic polymerizable liquid crystal compound (liquid crystal monomer) was applied. A cured layer of a polymerizable liquid crystal compound having a thickness of 1 μm was formed on the alignment film of the base material by irradiation with ultraviolet rays and solidifying in a state where the refractive index anisotropy was maintained. The cured layer was a 1/4 wavelength retardation layer 1 having reverse wavelength dispersion. The light transmittance at a wavelength of 380 nm of the reverse wavelength dispersion 1/4 wavelength retardation layer 1 was 1%, and the logarithmic contact angle after corona treatment was 58°.

(Fabrication of positive C plate)

A base film (second base film) made of a polyethylene terephthalate resin (PET) film (thickness: 38 μm, temperature: 40° C., moisture permeability at 90% RH: 16 g/m ² ·24 hr) was prepared. A composition for forming a vertical alignment layer was applied to one side of the base film to a film thickness of 3 μm, and ultraviolet rays were irradiated at 200 mJ/cm ² to prepare a vertical alignment layer. On the vertical alignment film, a composition for forming a positive C plate containing a polymerizable liquid crystal compound was coated and dried. Thereafter, the coating film was irradiated with ultraviolet (UV) light to polymerize the polymerizable liquid crystal compound to form a cured layer of the polymerizable liquid crystal compound. The cured layer was a positive C plate. The light transmittance of the cured layer at a wavelength of 380 nm was 85%, and the logarithmic contact angle after corona treatment was 63°.

(Manufacture of laminated body)

Corona treatment was performed on the surface of the 1/4 wavelength retardation layer 1 and the hardened layer of the positive C plate. A coating film of a water-based adhesive was formed on the 1/4 wavelength retardation layer 1 so that the thickness of the water-based adhesive layer after drying was 0.1 μm. Thereafter, a release film (a triacetyl cellulose-based resin (TAC) film subjected to release treatment, thickness: 25 μm) was laminated on the coating film of the water-based adhesive, dried for 5 minutes in an air atmosphere at a temperature of 80 ° C., and then the release film was It peeled off to obtain a water-based adhesive layer having a thickness of 0.1 μm.

The water-based adhesive layer was subjected to corona treatment at 28 kJ/m ² , and then the positive C plate was bonded to form a PET film/orientation film/1/4 wavelength retardation layer/water-based adhesive layer/positive C plate/vertical alignment film/PET. A layered product having a film layer configuration was obtained. The curing step was performed by heating the obtained layered product in an air atmosphere at a temperature of 80°C for 10 minutes. The results are shown in Table 1.

<Example 2>

Except for using a triacetyl cellulose-based resin (TAC) film (thickness of 40 μm, temperature of 40° C., and water vapor transmission rate of 950 g/m ² 24 hr at a relative humidity of 90% RH) as the first base film in Example 1, In the same manner as in Example 1, a laminate having a layer configuration of TAC film/alignment film/1/4 wavelength retardation layer 1/water-based adhesive layer/positive C plate/vertical alignment film/PET film was obtained. The results are shown in Table 1.

<Comparative Example 1>

A laminate was produced in the same manner as in Example 1, except that the corona treatment was not performed on the water-based adhesive layer in Example 1. The results are shown in Table 1. Evaluation of adhesion was C, and the positive C plate and the water-based adhesive layer were not bonded together.

<Comparative Example 2>

(Manufacture of 1/2 wavelength retardation layer)

A base film (first base film) made of a triacetyl cellulose-based resin (TAC) film (thickness: 40 μm, temperature: 40° C., moisture permeability: 950 g/m ² ·24 hr at a relative humidity of 90% RH) was prepared. Alignment treatment was carried out by applying a composition for forming an alignment film on a base film and drying it. Then, on the alignment layer, a composition for forming a liquid crystal layer containing a nematic polymerizable liquid crystal compound is applied, and the orientation of the polymerizable liquid crystal compound is fixed by heating and UV irradiation, thereby polymerizing a thickness of 2 μm on the alignment layer of the substrate. A cured layer of a crystalline liquid crystal compound was formed. The cured layer was a 1/2 wavelength retardation layer. The light transmittance at a wavelength of 380 nm of the 1/2 wavelength retardation layer was 85%, and the logarithmic contact angle was 59°.

(Manufacture of 1/4 wavelength retardation layer 2)

A base film (second base film) made of a triacetyl cellulose-based resin (TAC) film (thickness: 40 μm, temperature: 40° C., moisture permeability at 90% RH: 950 g/m ² ·24 hr) was prepared. An alignment film (thickness of 1 μm) subjected to rubbing was formed on the base film. On the alignment film, a composition for forming a liquid crystal layer containing a rod-shaped nematic polymerizable liquid crystal compound (liquid crystal monomer) was applied. A cured layer of a polymerizable liquid crystal compound having a thickness of 1 μm was formed on the alignment film of the base material by irradiation with ultraviolet rays and solidifying in a state where the refractive index anisotropy was maintained. The hardened layer was the 1/4 wavelength retardation layer 2 of positive wavelength dispersion. The light transmittance at a wavelength of 380 nm of the quarter-wavelength retardation layer 2 having positive wavelength dispersion was 85%, and the logarithmic contact angle was 76°.

(Manufacture of laminated body)

In Example 1, except that the 1/2-wavelength retardation layer obtained above was used instead of the 1/4-wavelength retardation layer 1, and the 1/4-wavelength retardation layer 2 obtained above was used instead of the positive C plate. In the same manner as in 1, a laminate having a layer configuration of TAC film/alignment film/1/2 wavelength retardation layer/water-based adhesive layer/1/4 wavelength retardation layer 2/alignment film/TAC film was obtained. The results are shown in Table 1.

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: peeling film.

Claims (7)

The first retardation layer and the second retardation layer are bonded through a water-based adhesive layer,
The first retardation layer and the second retardation layer include a cured layer of a polymerizable liquid crystal compound,
A laminate wherein at least either 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 laminate according to claim 1, wherein one of the first retardation layer and the second retardation layer is a 1/4 wavelength retardation layer having reverse wavelength dispersion, and the other is a positive C plate. The method of claim 1 or 2, further comprising a first base film and a second base film,
The first base film is disposed on a side opposite to the side of the water-based adhesive layer in the first retardation layer,
The second base film is disposed on a side opposite to the water-based adhesive layer in the second retardation layer. The laminate according to claim 3, wherein both the first base film and the second base film have moisture 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;
A third step of bonding the first retardation layer and the second retardation layer through the water-based adhesive layer after surface activation treatment is performed on the surface of the water-based adhesive layer on the opposite side to the first retardation layer side in this order equipped with,
The method of manufacturing a laminate, wherein at least either one of the first retardation layer and the second retardation layer has a light transmittance at a wavelength of 380 nm of 10% or less. The manufacturing method of the laminated body of Claim 5 further equipped with the curing process of heating a laminated body after the said 3rd process. The method of claim 5 or 6, wherein the second step,
a step of laminating a release film on the coating film of the water-based adhesive;
The manufacturing method of the laminated body further provided with the process of peeling the said release film after drying the coating film of the said water-system adhesive layer.

Images