WO2021166578A1 - Optical multilayer body - Google Patents

Abstract

An optical multilayer body which sequentially comprises a polarizer, an adhesive layer and an optically anisotropic layer in this order, wherein: the optically anisotropic layer contains a cured product of a composition that contains a liquid crystalline compound having a polymerizable group and a photopolymerization initiator; the photopolymerization initiator contains a photopolymerization initiator having a base dissociation constant pKb of less than 8; the adhesive layer contains a resin (A); and the adhesive layer satisfies formula (1).

Description

Optical laminate

The present invention relates to an optical laminate, and further relates to a polarizing plate with an adhesive layer containing the same, an image display device, and a method for manufacturing the optical laminate.

Patent Document 1 has a polarizer, an adhesive layer, and an optically anisotropic layer in this order, and the optically anisotropic layer has a liquid crystal compound having a polymerizable group and a base dissociation constant pKb of 8 or more. A polarizing plate obtained by curing a composition containing a photopolymerization initiator is disclosed.

International Publication No. 2016/194792

In a polarizing plate having a polarizer, an adhesive layer, and an optically anisotropic layer in this order, the degree of polarization (Py) may decrease when a moist heat resistance test is performed.

The present invention has a polarizing element, an adhesive layer, and an optically anisotropic layer in this order, and a polarizing plate in which a decrease in the degree of polarization (Py) is suppressed even when a moist heat resistance test is performed, and an image including the polarizing plate. A display device and a method for manufacturing a polarizing plate are provided.

The present invention provides a method for manufacturing a polarizing plate, an image display device, a polarizing plate with an adhesive layer, and an optical laminate shown below.
[1] An optical laminate having a polarizer, an adhesive layer, and an optically anisotropic layer in this order, wherein the optically anisotropic layer is a liquid crystal compound having a polymerizable group and a photopolymerization initiator. Is a layer containing a cured product of a composition containing
The photopolymerization initiator comprises a photopolymerization initiator having a base dissociation constant pKb of less than 8.
The pressure-sensitive adhesive layer contains the resin (A) and contains.
The pressure-sensitive adhesive layer is an optical laminate satisfying the following formula (1).
0 ≤ α ≤ 60 (1)
[In the formula, α represents the product of the content (mass%) of the acid component in all the monomer components constituting the resin (A) and the thickness (μm) of the pressure-sensitive adhesive layer. ]
[2] The optical laminate according to [1], wherein the content of the acid component in all the monomer components constituting the resin (A) is 0% by mass or more and 1.0% by mass or less.
[3] The optical laminate according to [1] or [2], wherein the thickness of the pressure-sensitive adhesive layer is 100 μm or less.
[4] The optical laminate according to any one of [1] to [3], wherein a protective film is provided on the side of the polarizer opposite to the optically anisotropic layer side.
[5] Polarized light with an adhesive layer, which has the optical laminate according to any one of [1] to [4] and further includes an adhesive layer on the side opposite to the polarizer side of the optically anisotropic layer. Board.
[6] An image display device including the polarizing plate with an adhesive layer according to [5].
[7] The method for manufacturing an optical laminate according to [1].
The step of preparing the polarizer,
A step of curing a composition containing a liquid crystal compound having a polymerizable group and a photopolymerization initiator to form an optically anisotropic layer.
A method for producing an optical laminate, which comprises a step of forming a pressure-sensitive adhesive layer containing the resin (A) and a step of bonding the polarizer and the optically anisotropic layer via the pressure-sensitive adhesive layer.

The content of the acid component in all the monomer components constituting the resin (A) contained in the pressure-sensitive adhesive layer has an acidic group with respect to the mass of all the monomers for producing the resin (A). The mass content of the monomer is expressed as a mass ratio. The pressure-sensitive adhesive layer may contain a plurality of types of resin (A), in which case the monomer having an acidic group with respect to the mass of all the monomers for producing the plurality of types of resin (A). The mass content may be determined.

According to the present invention, a polarizing plate having a polarizer, a pressure-sensitive adhesive layer, and an optically anisotropic layer in this order, and a polarizing plate in which a decrease in the degree of polarization (Py) is suppressed even when a wet heat resistance test is performed. An image display device including the same and a method for manufacturing a polarizing plate can be provided.

It is a schematic cross-sectional view which shows an example of the layer structure of the optical laminated body of this invention. It is a schematic cross-sectional view which shows an example of the layer structure of the polarizing plate with an adhesive layer 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 is appropriately adjusted to make it easier to understand each component, and the scale of each component shown in the drawings does not necessarily match the scale of the actual component.

<Optical laminate>
The optical laminate in the present disclosure will be described with reference to FIG. As shown in FIG. 1, the optical laminate 1 can be configured by laminating a polarizer 2, an adhesive layer 3, and an optically anisotropic layer 4 in this order. Although not shown, the optical laminate 1 may have a layer other than the layer shown in FIG. 1, for example, a protective film and an adhesive layer described later.

(Polarizer)
The polarizer 2 is an absorption type polarizer having a property of absorbing linearly polarized light having a vibration plane parallel to its absorption axis and transmitting linearly polarized light having a vibration plane orthogonal to the absorption axis (parallel to the transmission axis). Can be. As the polarizer 2, a polarizer in which a dichroic dye is adsorbed and oriented on a uniaxially stretched polyvinyl alcohol-based resin film can be preferably used. The polarizer 2 is, for example, a step of uniaxially stretching a polyvinyl alcohol-based resin film; a step of adsorbing a dichroic dye by dyeing the polyvinyl alcohol-based resin film with a dichroic dye; polyvinyl having the dichroic dye adsorbed. It can be produced by a method including a step of treating the alcohol-based resin film with a cross-linking solution such as an aqueous boric acid solution; and a step of washing with water after the treatment with the cross-linking solution.

As the polyvinyl alcohol-based resin, a saponified polyvinyl acetate-based resin can be used. Examples of the polyvinyl acetate-based resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and a copolymer of vinyl acetate and another monomer copolymerizable with the vinyl acetate. 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. As used herein, the term "(meth) acrylic" means at least one selected from acrylic and methacryl. The same applies to "(meth) acryloyl", "(meth) acrylate" and the like.

The saponification degree of the polyvinyl alcohol-based resin is usually 85 mol% or more and 100 mol% or less, preferably 98 mol% or more and 100 mol% or less. The polyvinyl alcohol-based resin may be modified, and for example, polyvinyl formal or polyvinyl acetal modified with aldehydes can be used. The average 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 average degree of polymerization of the polyvinyl alcohol-based resin can be determined in accordance with JIS K 6726.

A film formed of such a polyvinyl alcohol-based resin is used as a raw film for a polarizer. The method for forming a film of the polyvinyl alcohol-based resin is not particularly limited, and a known method is adopted. The thickness of the polyvinyl alcohol-based raw film is not particularly limited, but can be determined so that a polarizer having a preferable thickness, which will be described later, can be produced.

The uniaxial stretching of the polyvinyl alcohol-based resin film can be performed before dyeing the dichroic dye, at the same time as dyeing, or after dyeing. If the uniaxial stretching is performed after staining, the uniaxial stretching may be performed before or during the cross-linking treatment. Moreover, uniaxial stretching may be performed in these a plurality of steps.

In uniaxial stretching, rolls having different peripheral speeds may be uniaxially stretched, or thermal rolls may be used to uniaxially stretch. The uniaxial stretching may be a dry stretching in which the film is stretched in the atmosphere, or a wet stretching in which the polyvinyl alcohol-based resin film is swollen with a solvent or water. The draw ratio is usually 3 times or more and 8 times or less.

As a method of dyeing a polyvinyl alcohol-based resin film with a dichroic dye, for example, a method of immersing the polyvinyl alcohol-based resin film in an aqueous solution containing a dichroic dye is adopted. As the dichroic dye, iodine or a dichroic organic dye is used. The polyvinyl alcohol-based resin film is preferably immersed in water before the dyeing treatment.

As the cross-linking treatment after dyeing with a dichroic dye, a method of immersing the dyed polyvinyl alcohol-based resin film in a boric acid-containing aqueous solution is usually adopted. When iodine is used as the dichroic pigment, the boric acid-containing aqueous solution preferably contains potassium iodide.

The thickness of the polarizer 2 is usually 30 μm or less, preferably 20 μm or less, more preferably 15 μm or less, and further preferably 13 μm or less. The thickness of the polarizer 2 is usually 2 μm or more, preferably 3 μm or more.

(Adhesive layer)
The pressure-sensitive adhesive layer 3 is arranged between the polarizer 2 and the optically anisotropic layer 4. The pressure-sensitive adhesive layer 3 can bond the polarizer 2 or the linear polarizing plate described later with the optically anisotropic layer 4. The pressure-sensitive adhesive layer 3 may be composed of one layer or two or more layers, but is preferably composed of one layer. The pressure-sensitive adhesive layer 3 is preferably laminated in contact with the polarizer 2 or the linear polarizing plate. Further, the pressure-sensitive adhesive layer 3 is preferably laminated in contact with the optically anisotropic layer 4.

The pressure-sensitive adhesive layer 3 contains the resin (A). The resin (A) may be, for example, a (meth) acrylic-based, rubber-based, urethane-based, ester-based, silicone-based, or polyvinyl ether-based resin. The resin (A) is preferably a (meth) acrylic resin from the viewpoint of transparency, weather resistance and heat resistance. The resin (A) for forming the pressure-sensitive adhesive layer 3 may be hereinafter referred to as a “base polymer”. The pressure-sensitive adhesive layer 3 may contain only one type of resin (A), or may contain two or more types of resin (A).

Examples of (meth) acrylic resins include butyl (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, and lauryl (meth) acrylate. , (Meta) Isooctyl acrylate, (Meta) Isodecyl acrylate, (Meta) 2-ethylhexyl acrylate, (Meta) Isobornyl acrylate, etc. One or more of (meth) acrylic acid esters as monomer components It can be a polymer or a copolymer. The (meth) acrylic resin may be a copolymer of a polar monomer. 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 (). Examples thereof include monomers having a carboxylic acid group, a carboxyl group, a hydroxyl group, an amide group, an amino group, an epoxy group and the like, such as a meta) acrylate. However, when the polar monomer is copolymerized, when the polar monomer is an acidic group such as a carboxylic acid group (when the polar monomer is (meth) acrylic acid, etc.), the content of the acid component is within the above range. Therefore, it is necessary to adjust the copolymerization ratio.

(Adhesive composition)
The pressure-sensitive adhesive layer 3 can be composed of a pressure-sensitive adhesive composition containing the resin (A). The pressure-sensitive adhesive composition may be an active energy ray-curable type or a thermosetting type. The pressure-sensitive adhesive layer 3 is preferably composed of a pressure-sensitive adhesive composition using a (meth) acrylic resin as a base polymer from the viewpoint of transparency, weather resistance and heat resistance.

The pressure-sensitive adhesive composition may contain only the above-mentioned base polymer, but usually further contains a cross-linking agent. As a cross-linking agent, when a carboxylic acid group is present in the (meth) acrylic resin, a divalent or higher valent metal ion that forms a metal salt with the carboxylic acid group; with the carboxylic acid group. Polyamine compounds that form amide bonds; Polyamine compounds that form amide bonds by ester-amide exchange reaction when the (meth) acrylic resin has an acid ester bond (carboxyl group); Polyepoxy compounds and A polyol that forms an ether bond with a hydroxy group, or, as described above, if the base polymer has a carboxyl group, an ester bond is formed with the carboxyl group; a polyisocyanate compound. Examples thereof include those that form an ester bond with a hydroxy group and those that form an amide bond with a carboxyl group. Among these, a polyisocyanate compound is preferable. As the cross-linking agent, one having no acidic group such as a carboxylic acid group is usually used.

Examples of the polyisocyanate compound include an aliphatic isocyanate compound (for example, hexamethylene diisocyanate), an alicyclic isocyanate compound (for example, isophorone diisocyanate), a hydrogenated xylylene diisocyanate, a hydrogenated diphenylmethane diisocyanate, and an aromatic isocyanate compound. (For example, tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate, etc.) and the like. Further, the polyisocyanate compound is an adduct (adduct) of the above isocyanate compound made of a polyhydric alcohol compound [for example, an adduct made of glycerol, trimethylpropane, etc.], an isocyanurate compound, a bullet-type compound, a polyether polyol, or a polyester. It may be a derivative such as a urethane prepolymer type isocyanate compound which has been subjected to an addition reaction with a polyol, an acrylic polyol, a polybutadiene polyol, a polyisoprene polyol or the like. The polyisocyanate compound can be used alone or in combination of two or more. Of these, from the viewpoint of durability, tolylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate and their polyhydric alcohol compounds or their isocyanurate compounds are preferable.

The ratio of the cross-linking agent to 100 parts by mass of the base polymer is, for example, 0.01 parts by mass or more and 10 parts by mass or less, preferably 0.1 parts by mass or more and 3 parts by mass or less, and more preferably 0.1 parts by mass or more and 1 part by mass. It may be less than a part by mass.

The 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 and electron beams, and has adhesiveness even before irradiation with active energy rays. It is an adhesive composition having a property that it can be brought into close contact with an adherend such as, etc., and can be cured by irradiation with active energy rays to adjust the adhesive force and the like.
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 cross-linking agent. Further, if necessary, a photopolymerization initiator, a photosensitizer, or the like may be contained.
The active energy ray-polymerizable compound is, for example, a (meth) acrylate monomer having at least one (meth) acryloyloxy group in the molecule; obtained by reacting two or more kinds of functional group-containing compounds, and at least in the molecule. Examples thereof include (meth) acrylic compounds such as (meth) acryloyloxy group-containing compounds such as (meth) acrylate oligomers having two (meth) acryloyloxy groups.

The pressure-sensitive adhesive composition may further contain a silane compound. By containing the silane compound, the adhesion between the pressure-sensitive adhesive layer and the layer to be laminated can be enhanced. Two or more kinds of silane compounds may be used.

Examples of the silane compound include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, and 3-glycid. Xipropylmethyldimethoxysilane, 3-glycidoxypropylethoxydimethylsilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, 3-methacryloyl Examples thereof include oxypropyltrimethoxysilane and 3-mercaptopropyltrimethoxysilane.

Further, the silane compound can contain an oligomer derived from the above silane compound.

The content of the silane compound in the pressure-sensitive adhesive composition is usually 0.01 parts by mass or more and 10 parts by mass or less, preferably 0.03 parts by mass or more and 5 parts by mass or less, based on 100 parts by mass of the base polymer. It is more preferably 0.05 part by mass or more and 2 parts by mass or less, and further preferably 0.1 part by mass or more and 1 part by mass or less.

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, pressure-sensitive adhesives, and fillers (metal powders and other inorganic powders). Etc.), antioxidants, UV absorbers, dyes, pigments, colorants, antifoaming agents, corrosion inhibitors, photopolymerization initiators and other additives can be included.

The pressure-sensitive adhesive layer 3 can be formed by applying, for example, an organic solvent diluent of the above-mentioned pressure-sensitive adhesive composition on a substrate and drying it. When the active energy ray-curable pressure-sensitive adhesive composition is used, the formed pressure-sensitive adhesive layer can be irradiated with active energy rays to obtain a cured product having a desired degree of curing.

The pressure-sensitive adhesive layer 3 satisfies the formula (1).
0 ≤ α ≤ 60 (1)
[In the formula, α represents the product of the content rate (mass%) of the acid component in all the monomer components constituting the resin (A) and the thickness (μm) of the pressure-sensitive adhesive layer. ]
When the pressure-sensitive adhesive composition satisfies the above formula, the optically anisotropic layer is a cured product of the composition containing a liquid crystal compound having a polymerizable group and a photopolymerization initiator having a base dissociation constant pKb of less than 8. Even when the layer contains the layer, the degree of polarization (Py) of the optical laminate tends to be less likely to decrease in the moist heat resistance test.

As described above, examples of the acid component include a monomer having an acidic group such as a carboxyl group. Examples of the monomer having a carboxyl group include (meth) acrylic acid and the like. From the content of the acid component constituting the resin (A) and the thickness of the pressure-sensitive adhesive layer (preferable range will be described later), α can be easily obtained to satisfy the formula (1). When the pressure-sensitive adhesive layer contains two or more kinds of resins (A), the content rate (mass%) of the acid component is the total monomer component (including the acid component) used for producing all the resins (A). It is the ratio of the mass of the acid component to the mass.

The upper limit of α in the formula (1) is preferably 50 or less, more preferably 45 or less, still more preferably 40 or less, from the viewpoint of suppressing a decrease in the degree of polarization (Py) of the optical laminate in the wet heat durability test. It is particularly preferably 30 or less, and particularly preferably 25 or less. The lower limit of α in the formula (1) may be, for example, 0.01 or more, 0.1 or more, or 1 or more.

The content of the acid component in all the monomer components constituting the resin (A) may be, for example, 5% by mass or less, preferably 4% by mass or less, more preferably 3% by mass or less, and further preferably 2% by mass. Hereinafter, it is particularly preferably 1% by mass or less. The content of the acid component in all the monomer components constituting the resin (A) is preferably 0% by mass or more and 1.0% by mass or less, for example, 0.01% by mass or more or 0.1% by mass or more. May be good. It is particularly preferable that the acid component is not contained in all the monomer components constituting the resin (A).

The thickness of the pressure-sensitive adhesive layer 3 may be, for example, 100 μm or less, preferably 1 μm or more and 100 μm or less, more preferably 2 μm or more and 70 μm or less, still more preferably 3 μm or more and 50 μm or less, and particularly preferably 5 μm or more. It is 25 μm or less.

(Optically anisotropic layer)
The optically anisotropic layer 4 is a composition containing a liquid crystal compound having a polymerizable group (hereinafter, also referred to as a polymerizable liquid crystal compound) and a photopolymerization initiator (hereinafter, also referred to as a cured product layer forming composition). It is composed of a layer containing a cured product (hereinafter, also referred to as a cured product layer). The composition for forming a cured product layer used in the present invention is preferably liquid. The liquid cured product layer forming composition has an advantage that a film-like sheet-like cured product layer can be easily formed by casting and applying it on an appropriate base material. Here, the "liquid" cured product layer forming composition is a solution formed by dissolving a liquid crystal compound or a photopolymerization initiator contained in the cured product layer forming composition in an applicable solvent (described later). It is a concept including a composition for forming a cured product layer.

The photopolymerization initiator includes a photopolymerization initiator having a base dissociation constant pKb of less than 8. In the present specification, the base dissociation constant (pKb) refers to pKb at a temperature of 25 ° C., and typically refers to the base dissociation constant (pKb) in an aqueous solution having a water temperature of 25 ° C. to quantify the strength of a base. It is one of the indexes to express the basicity, and is synonymous with the basicity constant. The base dissociation constant (pKb) is determined by A.I. E. Martell, R.M. M. Smith, "Critical Stability Constants", Vol. The acid dissociation constant (pKa) can be obtained by the method described in 1-3, Plenum Press (1974, 1975, 9177), and then can be obtained from the formula of pKb = 14.0-pKa.

According to the findings of the present inventors, when the cured product layer forming composition contains a photopolymerization initiator having a base dissociation constant pKb of less than 8, the degree of polarization (Py) tends to decrease in the moist heat resistance test. It was found that there is. According to the present invention, the optically anisotropic layer has a base dissociation constant pKb of less than 8 by satisfying the above formula (1) in an optical laminate having a polarizer, an adhesive layer, and an optically anisotropic layer in this order. Even when it is formed from a composition for forming a cured product layer containing a certain photopolymerization initiator, it is possible to suppress a decrease in the degree of polarization (Py) in a moist heat resistance test.

Examples of the photopolymerization initiator having a base dissociation constant pKb of less than 8 include compounds having a morpholine skeleton. Typical commercially available products include, for example, Irgacure 907 (pKb = 5.6), Irgacure 369 (pKb = 5.3) and Irgacure 379 (pKb = 5.4) manufactured by BASF.

The cured product layer forming composition includes a photopolymerization initiator having a base dissociation constant pKb of less than 8 and a photopolymerization initiator having a base dissociation constant pKb of 8 or more (hereinafter, also referred to as other photopolymerization initiators). ) Can be contained in an amount of 1 or more, but the composition for forming a cured product layer preferably contains only one or more photopolymerization initiator having a base dissociation constant pKb of less than 8.

The optically anisotropic layer 4 may have an orientation layer described later. When the optically anisotropic layer 4 is formed on a base material as described later, this base material is usually removed when the optically anisotropic layer 4 is attached to a polarizer or a linear polarizing plate. The "cured product" refers to a state in which the formed layer alone can exist independently without being deformed or flowing.

The optically anisotropic layer 4 may be a layer that gives a phase difference of λ / 2, a layer that gives a phase difference of λ / 4, or a positive C layer, and is a laminate of at least two of these layers (hereinafter, phase difference). It may also be a layered laminate). Examples of the retardation layer laminate include a laminate of a layer giving a phase difference of λ / 2 and a layer giving a phase difference of λ / 4, and a layer giving a phase difference of λ / 4 and a positive C layer. Laminates and the like can be mentioned. The optical laminated body 1 can exhibit a function as a circular polarizing plate by laminating an optically anisotropic layer 4 including a layer giving a phase difference of λ / 4 on a polarizer 2 or a linear polarizing plate described later. ..

In the present specification, the "layer giving a phase difference of λ / 4" is a phase difference layer that converts linearly polarized light having a specific wavelength into circularly polarized light (or circularly polarized light into linearly polarized light).
In the present specification, the “layer that gives a phase difference of λ / 2” is a phase difference layer that converts the polarization direction of linearly polarized light having a specific wavelength by 90 °.
In the present specification, the “positive C layer” means the refractive index in the slow axis direction in the _{plane is n x} , the refractive index in the phase advance axis direction in the plane is n _y , and the refractive index in the thickness direction is n. _{When z} is set, it is a layer that satisfies the relationship of _{n z} > n _x = n _y. If the difference between _{the value of n x and} the value of n _{y is within 0.5% of the value of n y} , it can be substantially regarded as n _x = n _y, and it must be within 0.3%. Is more preferable.

The thickness of the optically anisotropic layer 4 is preferably 0.5 μm or more. The thickness of the optically anisotropic layer 4 is preferably 10 μm or less, and more preferably 5 μm or less. The above-mentioned upper limit value and lower limit value can be arbitrarily combined. When the optically anisotropic layer 4 is at least the above lower limit value, sufficient durability can be obtained. When the thickness of the optically anisotropic layer 4 is not more than the above upper limit value, it can contribute to thinning the optical laminate 1. The thickness of the optically anisotropic layer 4 is a desired in-plane retardation value of a layer giving a phase difference of λ / 4, a layer giving a phase difference of λ / 2, or a positive C layer, and a retardation value in the thickness direction. Can be adjusted to obtain. When the optically anisotropic layer 4 is a laminated body of two or more layers as described above, the total thickness of each of the two or more layers is defined as the thickness of the optically anisotropic layer 4.

Hereinafter, the polymerizable liquid crystal compound and the photopolymerization initiator contained in the composition for forming the optically anisotropic layer 4, and optionally the additives contained in the composition will be described. As described above, the composition for forming a cured product layer used in the present invention is preferably liquid (as described above, the concept including a "solution"). Therefore, as described later, the composition for forming a cured product layer. Is preferably containing a solvent. The solvent is preferably one that is cast-coated on an appropriate substrate and then removed by, for example, drying. Therefore, the cured product layer-forming composition is described below by drying or the like. The composition for forming a cured product layer, excluding the solvent and the like that can be removed by the above, may be referred to as "solid content".

(Polymerizable liquid crystal compound)
The polymerizable liquid crystal compound is a compound having a polymerizable group and can be in a liquid crystal state. The polymerizable liquid crystal compound is cured by reacting the polymerizable groups of the polymerizable liquid crystal compound with each other to polymerize the polymerizable liquid crystal compound.

The type of the polymerizable liquid crystal compound is not particularly limited, but can be classified into a rod-shaped type (rod-shaped liquid crystal compound) and a disk-shaped type (disk-shaped liquid crystal compound, discotic liquid crystal compound) according to its shape. Further, there are a small molecule type and a high molecular type, respectively. The polymer generally means a polymer having a degree of polymerization of 100 or more (Polymer Physics / Phase Transition Dynamics, Masao Doi, 2 pages, Iwanami Shoten, 1992).

In this embodiment, any polymerizable liquid crystal compound can be used. Further, two or more kinds of rod-shaped liquid crystal compounds, two or more kinds of disk-shaped liquid crystal compounds, or a mixture of a rod-shaped liquid crystal compound and a disk-shaped liquid crystal compound can also be used.

As the rod-shaped liquid crystal compound, for example, the compound described in claim 1 of JP-A No. 11-513019 can be preferably used. As the disk-shaped liquid crystal compound, for example, those described in paragraphs [0020] to [0067] of JP-A-2007-108732 or paragraphs [0013] to [0108] of JP-A-2010-244038 are preferably used. Can be used.

When two or more types of polymerizable liquid crystal compounds are used in combination, at least one of the polymerizable liquid crystal compounds has two or more polymerizable groups in the molecule. That is, the cured layer of the polymerizable liquid crystal compound is preferably a layer formed by fixing a liquid crystal compound having a polymerizable group by polymerization. In this case, it is no longer necessary to exhibit liquid crystallinity after forming a layer.

As the polymerizable group of the polymerizable liquid crystal compound, for example, a functional group capable of an addition polymerization reaction such as a polymerizable ethylenically unsaturated group or a ring-polymerizable group is preferable. More specifically, examples of the polymerizable group include a (meth) acryloyl group, a vinyl group, a styryl group, and an allyl group. Among them, the (meth) acryloyl group is preferable. The (meth) acryloyl group is a concept that includes both a meta-acryloyl group and an acryloyl group.

The liquid crystal property of the polymerizable liquid crystal compound may be a thermotropic liquid crystal or a riotropic liquid crystal, and when the thermotropic liquid crystal is classified according to the order, it may be a nematic liquid crystal or a smectic liquid crystal.

(Other photopolymerization initiators)
The composition for forming a cured product layer used in the present invention contains a photopolymerization initiator having a base dissociation constant pKb of less than 8, but a photopolymerization initiator (another photopolymerization initiator) other than such a photopolymerization initiator is used. It can also be included. Examples of such other photopolymerization initiators include acetophenones, benzoins, benzophenones, phosphine oxides, ketals, anthraquinones, thioxanthones, azo compounds, peroxides, and 2,3-dialkyldione compounds. Examples thereof include isophotopolymerization initiators such as disulfide compounds, fluoroamine compounds, aromatic sulfoniums, loffin dimers, onium salts, borate salts, active esters, active halogens, inorganic complexes, and coumarins. Typical commercially available products of other photopolymerization initiators include, for example, Irgacure 127 (pKb = 13), Irgacure 184 (pKb = 17) and Irgacure 819 (pKb = 24) manufactured by BASF.

(Composition for forming a cured product layer)
The content of the polymerizable liquid crystal compound in the composition for forming the cured product layer may be, for example, 50% by mass or more and 99% by mass or less, preferably 60% by mass, based on the solid content of the composition for forming the cured product layer. It is 95% by mass or less.

The content of the photopolymerization initiator in the cured product layer forming composition may be, for example, 0.01% by mass or more and 20% by mass or less, preferably 0, based on the solid content of the cured product layer forming composition. It is 5.5% by mass or more and 5% by mass or less.

The cured product layer forming composition may contain a polymerizable monomer from the viewpoint of the uniformity of the coating film and the strength of the film. Examples of the polymerizable monomer include radically polymerizable or cationically polymerizable compounds. Among them, a polyfunctional radically polymerizable monomer is preferable.

The polymerizable monomer is preferably one that can be copolymerized with the above-mentioned polymerizable liquid crystal compound. The amount of the polymerizable monomer used is preferably 1 part by mass or more and 50 parts by mass or less, and more preferably 2 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the polymerizable liquid crystal compound.

Further, the composition for forming the cured product layer may contain a surfactant from the viewpoint of the uniformity of the coating film and the strength of the film. Examples of the surfactant include conventionally known compounds. Among them, fluorine-based compounds are particularly preferable.

As described above, the cured product layer forming composition applied to the present invention is preferably liquid, and the cured product layer forming composition contains a solvent. As the solvent in this case, it is preferable that the polymerizable liquid crystal compound and the photopolymerization initiator have high solubility, and therefore, an organic solvent is preferably used. Examples of the organic solvent include amide (eg, N, N-dimethylformamide), sulfoxide (eg, dimethyl sulfoxide), heterocyclic compound (eg, pyridine), hydrocarbon (eg, benzene, hexane), alkyl halide (eg, eg). , Chloroform, dichloromethane), esters (eg, methyl acetate, ethyl acetate, butyl acetate), ketones (eg, acetone, methyl ethyl ketone), ethers (eg, tetrahydrofuran, 1,2-dimethoxyethane). Among them, alkyl halides and ketones are preferable. Further, two or more kinds of organic solvents may be used in combination.

In addition, the composition for forming the cured product layer includes vertical alignment promoters such as a polarizer interface side vertical alignment agent and an air interface side vertical alignment agent, and a polarizer interface side horizontal alignment agent, an air interface side horizontal alignment agent, and the like. Various orienting agents such as the horizontal alignment accelerator of the above may be contained. Further, the composition for forming a cured product layer may contain other components such as an adhesion improver, a plasticizer, and a polymer (thickener and the like) in addition to the above components.

(Cured material layer)
In the optical laminate of the present invention, the optically anisotropic layer contained in the optical laminate includes a cured product layer as described above. The cured product layer can be formed by applying a composition for forming a cured product layer, for example, onto an oriented layer and irradiating it with active energy rays. More specifically, the composition for forming a cured product layer is provided on an appropriate base material, the composition for forming a cured product layer is coated on the oriented layer, and the composition for forming a cured product layer is coated on the oriented layer. It is obtained by converting the polymerizable liquid crystal compound contained in the above into a cured product layer by polymerizing it by irradiating it with active energy rays.

The active energy rays include ultraviolet rays, visible light, electron beams, and X-rays, and are preferably ultraviolet rays. Examples of the light source of the active energy ray include a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a xenon lamp, a halogen lamp, a carbon arc lamp, a tungsten lamp, a gallium lamp, an excima laser, and a wavelength range. Examples thereof include LED light sources that emit light of 380 to 440 nm, chemical lamps, black light lamps, microwave-excited mercury lamps, metal halide lamps, and the like.

The irradiation intensity of ultraviolet light is usually the case of ultraviolet B wave (or wavelength range 280 nm 310 nm or less), 100 mW / cm ² or more 3,000 mW / cm ² or less. The ultraviolet irradiation intensity is preferably an intensity in a wavelength region effective for activating the cationic polymerization initiator or the radical polymerization initiator. The time for irradiating ultraviolet rays is usually 0.1 seconds or more and 10 minutes or less, preferably 0.1 seconds or more and 5 minutes or less, more preferably 0.1 seconds or more and 3 minutes or less, and further preferably 0. . 1 second or more and 1 minute or less.

Ultraviolet rays can be irradiated once or in a plurality of times. Depending on the polymerization initiator used, the accumulated amount of light at a wavelength of 365nm is preferably in a 700 mJ / cm ² or more, more preferably, to 1,100mJ / cm ² or more, 1,300mJ / cm ² or more and It is more preferable to do so. The integrated light intensity is advantageous for increasing the polymerization rate of the polymerizable liquid crystal compound constituting the liquid crystal layer 103 and improving the heat resistance. Integrated light intensity at a wavelength of 365nm is preferably in a 2,000 mJ / cm ² or less, and more preferably to 1,800mJ / cm ² or less. The integrated light intensity may cause coloring of the liquid crystal layer 103.

When the optically anisotropic layer 4 is a retardation layer laminate composed of two or more cured product layers, each cured product layer may be laminated using an adhesive, or the cured product already formed may be laminated. A composition for forming a cured product layer containing a polymerizable liquid crystal compound may be applied to the surface of the material layer and cured. The composition for forming the cured product layer in this case may be the same as or different from the existing composition for forming the cured product layer on which the cured product layer is formed.

(Base material)
The cured product layer can be formed on, for example, an orientation layer provided on the base material. The base material may be a long base material having a function of supporting the alignment layer. This base material functions as a releasable support and can support an optically anisotropic layer (phase difference layer) or an orientation layer for transfer. Further, it is preferable that the surface has an adhesive force that can be peeled off. The base material is a translucent, preferably optically transparent thermoplastic resin, for example, a polyolefin such as a chain polyolefin resin (polypropylene resin or the like) or a cyclic polyolefin resin (norbornen resin or the like). Based resin; Cellulosic resin such as triacetyl cellulose and diacetyl cellulose; Polyester based resin such as polyethylene terephthalate and polybutylene terephthalate; Polycarbonate resin; (Meta) acrylic resin such as methyl methacrylate resin; Polystyrene based Resin; Polyvinyl chloride resin; Acrylonitrile / butadiene / styrene resin; Acrylonitrile / styrene resin; Polyvinyl acetate resin; Polyvinylidene chloride resin; Polyamide resin; Polyacetal resin; Modified polyphenylene ether resin; Polysulfone type A film made of a resin; a polyether sulfone-based resin; a polyarylate-based resin; a polyamide-based resin; a polyimide-based resin; a maleimide-based resin, or the like can be used.

The base material may be subjected to various blocking prevention treatments. Examples of the blocking prevention treatment include an easy-adhesion treatment, a treatment of kneading a filler and the like, an embossing treatment (knurling treatment) and the like. By applying such a blocking prevention treatment to the base material, it is possible to effectively prevent the base materials from sticking to each other when the base material is wound, so-called blocking, and the productivity tends to be improved easily. be.

(Orientation layer)
The cured product layer is preferably formed on the substrate via the alignment layer. That is, the base material and the oriented layer are laminated in this order, and the cured product layer is laminated on the oriented layer.

The alignment layer is not limited to the vertically oriented layer, and may be an oriented layer that horizontally aligns the molecular axis of the polymerizable liquid crystal compound, or may be an oriented layer that obliquely orients the molecular axis of the polymerizable liquid crystal compound. .. The alignment layer has solvent resistance that does not dissolve due to coating of a composition containing a polymerizable liquid crystal compound, which will be described later, and heat resistance in heat treatment for removing the solvent and aligning the liquid crystal compound. preferable. Examples of the alignment layer include an alignment layer containing an orientation polymer, a photoalignment film, and a grub alignment layer in which an uneven pattern or a plurality of grooves are formed and oriented on the surface. The thickness of the oriented layer is usually in the range of 10 nm or more and 10000 nm or less.

Further, the alignment layer has a function of supporting the liquid crystal layer, and may function as a releasable support. A liquid crystal layer for transfer can be supported, and the surface thereof may have an adhesive force that can be peeled off.

As the resin used for the alignment layer, a resin obtained by polymerizing a polymerizable compound is used. The polymerizable compound is a compound having a polymerizable group, and is usually a non-liquid crystalline non-liquid crystal compound that does not become a liquid crystal state. The polymerizable groups of the polymerizable compound react with each other to polymerize the polymerizable compound, thereby forming a resin. Such a resin is a resin used as an alignment layer for orienting a polymerizable liquid crystal compound at the stage of forming the liquid crystal layer, and if it is not contained in the liquid crystal layer, it is used as a material for a known alignment layer. If there is no particular limitation, a cured product obtained by curing a conventionally known monofunctional or polyfunctional (meth) acrylate-based monomer under a polymerization initiator can be used. Specifically, examples of the (meth) acrylate-based monomer include 2-ethylhexyl acrylate, cyclohexyl acrylate, diethylene glycol mono2-ethylhexyl ether acrylate, diethylene glycol monophenyl ether acrylate, tetraethylene glycol monophenyl ether acrylate, and trimethyl propanetriacrylate. , Lauryl acrylate, lauryl methacrylate, isobornyl acrylate, isobornyl methacrylate, 2-phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, 2-hydroxypropyl acrylate, benzyl acrylate, tetrahydrofurfuryl methacrylate, 2-hydroxyethyl methacrylate, benzyl methacrylate. , Cyclohexyl methacrylate, methacrylic acid, urethane acrylate and the like can be exemplified. The resin may be one of these or a mixture of two or more.
The oriented layer can be peeled off together with the base material before and after the step of forming the cured product layer and then laminating it with the polarizer 2 or the linear polarizing plate.

Further, an orientation layer can be included in the cured product layer for the purpose of improving the peelability from the base material and imparting film strength to the cured product layer. When the cured product layer contains an oriented layer, it is preferable to use a cured product obtained by curing a monofunctional or bifunctional (meth) acrylate-based monomer, an imide-based monomer, or a vinyl ether-based monomer as the resin used for the oriented layer.
Examples of the monofunctional (meth) acrylate-based monomer include alkyl (meth) acrylates having 4 to 16 carbon atoms, βcarboxyalkyl (meth) acrylates having 2 to 14 carbon atoms, and alkylated phenyl (meth) having 2 to 14 carbon atoms. Examples thereof include acrylates, methoxypolyethylene glycol (meth) acrylates, phenoxypolyethylene glycol (meth) acrylates and isobonyl (meth) acrylates.
As the bifunctional (meth) acrylate-based monomer, 1,3-butanediol di (meth) acrylate; 1,3-butanediol (meth) acrylate; 1,6-hexanediol di (meth) acrylate; ethylene glycol di (Meta) acrylate; Diethylene glycol di (meth) acrylate; Neopentyl glycol di (meth) acrylate; Triethylene glycol di (meth) acrylate; Tetraethylene glycol di (meth) acrylate; Polyethylene glycol diacrylate; Bisphenol A bis (acrylate) Loyloxyethyl) ether; ethoxylated bisphenol A di (meth) acrylate; propoxylated neopentyl glycol di (meth) acrylate; ethoxylated neopentyl glycol di (meth) acrylate, 3-methylpentanediol di (meth) acrylate, etc. Can be mentioned.
Examples of the imide-based resin obtained by curing the imide-based monomer include polyamide and polyimide. The imide resin may be one of these or a mixture of two or more.
Further, the resin forming the alignment layer may contain a monomer other than the monofunctional or bifunctional (meth) acrylate-based monomer, the imide-based monomer and the vinyl ether-based monomer, but the monofunctional or bifunctional (meth) The content ratio of the acrylate-based monomer, the imide-based monomer, and the vinyl ether-based monomer may be 50% by mass or more, preferably 55% by mass or more, and more preferably 60% by mass or more in the total monomer. ..

When the alignment layer is included in the optically anisotropic layer 4, the thickness of the alignment layer is usually in the range of 10 nm or more and 10,000 nm or less, and the orientation of the optically anisotropic layer 4 is in-plane orientation with respect to the film surface. The thickness of the alignment layer is preferably 10 nm or more and 1000 nm or less, and when the orientation of the optically anisotropic layer 4 is perpendicular to the film surface, it is preferably 100 nm or more and 10000 nm or less. When the thickness of the optically anisotropic layer 4 is within the above range, it is possible to improve the peelability of the base material and impart appropriate film strength.

(Protective film)
The optical laminate can have one or more protective films. The protective film can have a function of protecting an optically anisotropic layer, a polarizer, and the like. The protective film may be arranged, for example, on one side or both sides of at least one of the polarizer and the optically anisotropic layer, preferably on the side opposite to the optically anisotropic layer side of the polarizer, and the optically anisotropic layer. It is arranged on at least one of the sides opposite to the polarizer side of the above, and more preferably on the side opposite to the optically anisotropic layer side of the polarizer. The protective film can be attached to another layer such as an optically anisotropic layer or a polarizer via an adhesive layer described later. A laminate composed of a polarizer and a protective film is also called a linear polarizing plate.

When the optical laminate is substantially rectangular and the protective film is a stretched film, it is preferable that the stretching direction of the protective film and the short side direction of the optical laminate (circular polarizing plate) are substantially parallel. .. When the stretching direction and the short side direction have such a relationship, the hue change of the circularly polarizing plate tends to be small in a high temperature environment regardless of the direction of the slow axis of the retardation film. When the stretching direction of the protective film is parallel to the short side, the shrinkage force in the stretching direction of the protective film due to the relaxation of stretching of the polarizer and the protective film in a high temperature environment becomes smaller than when it is parallel to the long side. , It is considered that the hue change becomes small.

The fact that the stretching direction of the protective film and the short side direction of the circularly polarizing plate are substantially parallel is not only when they are strictly parallel, but also when the angle between them is 0 ± 10 °. include. The angle formed by the stretching direction of the protective film and the short side direction of the circularly polarizing plate is preferably 0 ± 5 °.

The protective film is a translucent (preferably optically transparent) thermoplastic resin, for example, a polyolefin such as a chain polyolefin resin (polypropylene resin or the like) or a cyclic polyolefin resin (norbornen resin or the like). Based resin; Cellulosic resin such as triacetyl cellulose and diacetyl cellulose; Polyester based resin such as polyethylene terephthalate and polybutylene terephthalate; Polycarbonate resin; (Meta) acrylic resin such as methyl methacrylate resin; Polystyrene based Resin; Polyvinyl chloride resin; Acrylonitrile / butadiene / styrene resin; Acrylonitrile / styrene resin; Polyvinyl acetate resin; Polyvinylidene chloride resin; Polyamide resin; Polyacetal resin; Modified polyphenylene ether resin; Polysulfone system A film made of a resin; a polyether sulfone resin; a polyarylate resin; a polyamide imide resin; a polyimide resin or the like can be used.

As the chain polyolefin resin, polyethylene resin (polyethylene resin which is a homopolymer of ethylene or a copolymer mainly composed of ethylene), polypropylene resin (polypropylene resin which is a homopolymer of propylene or propylene as a main component) are used. In addition to homopolymers of chain olefins such as (copolymers), copolymers composed of two or more kinds of chain olefins can be mentioned.

Cyclic polyolefin resin is a general term for resins that are polymerized using a cyclic olefin as a polymerization unit, and is described in, for example, JP-A-1-240517, JP-A-3-14882, JP-A-3-122137, and the like. Resin is mentioned. Specific examples of the cyclic polyolefin resin include an open (co) polymer of a cyclic olefin, an addition polymer of a cyclic olefin, and a copolymer of a cyclic olefin and a chain olefin such as ethylene and propylene (typically). Is a random copolymer), and graft polymers obtained by modifying them with unsaturated carboxylic acids or derivatives thereof, and hydrides thereof. Of these, a norbornene-based resin using a norbornene-based monomer such as norbornene or a polycyclic norbornene-based monomer is preferably used as the cyclic olefin.

The polyester-based resin is a resin having an ester bond, excluding the following cellulose ester-based resin, and is generally composed of a polyvalent carboxylic acid or a polycondensate of a derivative thereof and a polyhydric alcohol. As the polyvalent 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 naphthalenedicarboxylic acid. As the polyhydric alcohol, a divalent diol can be used, and examples thereof include ethylene glycol, propanediol, butanediol, neopentyl glycol, and cyclohexanedimethanol. A typical example of the polyester resin is polyethylene terephthalate, which is a polycondensate of terephthalic acid and ethylene glycol.

The (meth) acrylic resin is a resin containing 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 copolymers; methyl methacrylate- (meth) acrylic acid. Ester copolymer; methyl methacrylate-acrylic acid ester- (meth) acrylic acid copolymer; (meth) methyl acrylate-styrene copolymer (MS resin, etc.); methyl methacrylate and alicyclic hydrocarbon group It contains a copolymer with the compound (for example, methyl methacrylate-cyclohexyl methacrylate copolymer, methyl methacrylate- (meth) norbornyl copolymer, etc.). _{A polymer containing poly (meth) acrylic acid C 1-6} alkyl ester as a main component, such as methyl poly (meth) acrylate, is preferably used, and more preferably methyl methacrylate is used as a main component (50% by mass). A methyl methacrylate-based resin having a content of 100% by mass or less, preferably 70% by mass or more and 100% by mass or less) is used.

Cellulose ester-based resin is an ester of cellulose and fatty acid. Specific examples of the cellulose ester resin include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. In addition, these copolymers and those in which a part of the hydroxyl group is modified with another substituent can also be mentioned. Among these, cellulose triacetate (triacetyl cellulose) is particularly preferable.

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

The thickness of the protective film is usually 1 μm or more and 100 μm or less, but from the viewpoint of strength and handleability, it is preferably 5 μm or more and 60 μm or less, more preferably 10 μm or more and 55 μm or less, and 15 μm or more and 40 μm or less. Is even more preferable.

When the optical laminate has two or more protective films, the protective film may be composed of the same type of thermoplastic resin or may be composed of different types of thermoplastic resins. Further, the thickness may be the same or different. Further, it may have the same phase difference characteristic or may have different phase difference characteristics.

As described above, at least one of the protective films has a hard coat layer, an antiglare layer, a light diffusion layer, an antireflection layer, a low refractive index layer, and an antistatic film on its outer surface (the surface opposite to the polarizer). It may be provided with a surface treatment layer (coating layer) such as an antifouling layer and an antifouling layer. The thickness of the protective film includes the thickness of the surface treatment layer.

(Adhesive layer)
The adhesive layer is arranged, for example, between the polarizer 2 and the protective film, or between the cured product layers in the retardation layer laminate, and can have a function of joining the layers. The adhesive layer may be a single layer or a multi-layer.

As the adhesive forming the adhesive layer, a water-based adhesive, an active energy ray-curable adhesive or a thermosetting adhesive can be used, and a water-based adhesive or an active energy ray-curable adhesive is preferable. As the pressure-sensitive adhesive layer, the above-mentioned pressure-sensitive adhesive layer can be used.

Examples of the water-based adhesive include an adhesive composed of a polyvinyl alcohol-based resin aqueous solution, a water-based two-component urethane-based emulsion adhesive, and the like. Of these, a water-based adhesive composed of an aqueous solution of a polyvinyl alcohol-based resin 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 co-polymers of vinyl acetate and other monomers copolymerizable therewith. A polyvinyl alcohol-based copolymer obtained by saponifying the polymer, or a modified polyvinyl alcohol-based polymer in which the hydroxyl groups thereof are partially modified can be used. The water-based adhesive may contain a cross-linking agent such as an aldehyde compound (glioxal or the like), an epoxy compound, a melamine compound, a methylol compound, an isocyanate compound, an amine compound, or a polyvalent metal salt.

When using a water-based adhesive, it is preferable to carry out a drying step for removing water contained in the water-based adhesive after the layers are bonded to each other. After the drying step, a curing step of curing at a temperature of, for example, 20 ° C. or higher and 45 ° C. or lower may be provided.

The active energy ray-curable adhesive is an adhesive containing a curable compound that is cured by irradiation with active energy rays such as ultraviolet rays, visible light, electron beams, and X-rays, and is preferably an ultraviolet curable adhesive. Is.

The curable compound can be a cationically polymerizable curable compound or a radically polymerizable curable compound. Examples of the cationically polymerizable curable compound include an epoxy compound (a compound having one or more epoxy groups in the molecule) and an oxetane compound (one or two or more oxetane rings in the molecule). Compounds), or a combination thereof. Examples of the radically polymerizable curable compound include a (meth) acrylic compound (a compound having one or more (meth) acryloyloxy groups in the molecule) and a radically polymerizable double bond. Other vinyl compounds or combinations thereof can be mentioned. A cationically polymerizable curable compound and a radically polymerizable curable compound may be used in combination. The active energy ray-curable adhesive usually further contains at least one of a cationic polymerization initiator and a radical polymerization initiator for initiating the curing reaction of the curable compound.

In order to enhance the adhesiveness, a surface activation treatment may be applied to at least one of the adhesive layer and the layer to be bonded to the adhesive layer. Surface activation treatment includes dry treatment such as corona treatment, plasma treatment, discharge treatment (glow discharge treatment, etc.), flame treatment, ozone treatment, UV ozone treatment, ionization active ray treatment (ultraviolet ray treatment, electron beam treatment, etc.). Wet treatments such as ultrasonic treatment using a solvent such as water or acetone, ionization treatment, and anchor coating treatment can be mentioned. These surface activation treatments may be performed alone or in combination of two or more.

When two or more adhesive layers are provided, the adhesives used for the adhesive layers may be of the same type or different types.

<Polarizing plate with adhesive layer>
The optical laminate may be a polarizing plate with an adhesive layer further provided with an adhesive layer on the side opposite to the polarizer side of the optically anisotropic layer. The polarizing plate 10 with an adhesive layer shown in FIG. 2 includes a protective film 11, an adhesive layer 12, a polarizer 2, an adhesive layer 3, an optically anisotropic layer 4, and an adhesive layer 13 in this order. In this case, in the optical laminate 10, the polarizer 2 may be a (straight) polarizing plate with a single-sided protective film having a protective film 10 via an adhesive layer 12. The pressure-sensitive adhesive layer 13 may be of the same type as the pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer 3, or may be of a different type. For the pressure-sensitive adhesive layer 13, the description of the pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer 3 is applied.

In a polarizing plate with an adhesive layer, the adhesive layer arranged between the polarizer and the optically anisotropic layer tends to have a large effect on the decrease in the degree of polarization (Py) in the moist heat resistance test. In a polarizing plate with a pressure-sensitive adhesive layer, it is preferable that the pressure-sensitive adhesive layer arranged between the polarizer and the optically anisotropic layer satisfies the above formula (1).

<Image display device>
The optical laminate 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, and an electroluminescence display device. .. When the optical laminate is applied to an image display device, it can be attached to the image display element so that the polarizer 2 side is the viewing side.

<Manufacturing method of optical laminate>
The optical laminate is a step of preparing a polarizer (polarizer preparation step) and a step of curing a composition containing a liquid crystal compound having a polymerizable group and a photopolymerization initiator to form an optically anisotropic layer (a step of forming an optically anisotropic layer). An optically anisotropic layer forming step), a step of forming a pressure-sensitive adhesive layer containing the resin (A) (a pressure-sensitive adhesive layer forming step), and a polarizer and an optically anisotropic layer are attached via the pressure-sensitive adhesive layer. Includes a bonding process (bonding process).

In the polarizer preparation step, the polarizer can be manufactured as described in the above description of the polarizer.

In the optically anisotropic layer forming step, the optically anisotropic layer is formed by applying a composition for forming a cured product layer containing a polymerizable liquid crystal compound on a base material and an alignment film if present, and the polymerizable liquid crystal compound. Can be produced by polymerizing. The composition for forming a cured product layer further contains a solvent and a polymerization initiator, and may further contain the above-mentioned other components, a photosensitizer, a polymerization inhibitor, a leveling agent, and the like. The base material and the alignment film may be incorporated into the optically anisotropic layer, or may not be separated from the optically anisotropic layer to become a component of the optical laminate.

The coating, drying and polymerization of the polymerizable liquid crystal compound of the composition for forming the cured product layer can be carried out by conventionally known coating methods, drying methods and polymerization methods.

For example, as a method for applying the composition for forming a cured product layer, a wire bar coating method, an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, a die coating method, or the like can be adopted.

The polymerization method of the polymerizable liquid crystal compound may be selected according to the type of the polymerizable group of the polymerizable liquid crystal compound. If the polymerizable group is a photopolymerizable group, it can be polymerized by a photopolymerization method. If the polymerizable group is a thermally polymerizable group, it can be polymerized by a thermal polymerization method. The photopolymerization method is preferable as the polymerization method of the polymerizable liquid crystal compound. In the photopolymerization method, it is not always necessary to heat the transparent base material to a high temperature, so that a transparent base material having low heat resistance can be used. The photopolymerization method is carried out by irradiating a film composed of a polarizer-forming composition or a retardation layer-forming composition containing a polymerizable liquid crystal compound with visible light or ultraviolet light. Ultraviolet light is preferable because it is easy to handle.

In the pressure-sensitive adhesive layer forming step, the pressure-sensitive adhesive composition can be prepared by first polymerizing the monomer components to prepare the resin (A) and then mixing the resin (A) with other components. The content of the acid component in the monomer component may be, for example, 0% by mass or more and 1.0% by mass or less.

Next, the pressure-sensitive adhesive layer can be prepared as a pressure-sensitive adhesive sheet. The pressure-sensitive adhesive sheet is prepared by dissolving or dispersing the pressure-sensitive adhesive composition in an organic solvent such as toluene or ethyl acetate to prepare a pressure-sensitive adhesive liquid, and forming a layer of the pressure-sensitive adhesive on a release film that has been subjected to a mold release treatment. It can be produced by forming it into a sheet shape and laminating another release film on the pressure-sensitive adhesive layer.

As a method of applying the adhesive liquid on the release film, a usual coating technique using a die coater, a comma coater, a reverse roll coater, a gravure coater, a rod coater, a wire bar coater, a doctor blade coater, an air doctor coater, etc. Should be adopted.

The release film is preferably composed of a plastic film and a release layer. Examples of the plastic film include polyester films such as polyethylene terephthalate film, polybutylene terephthalate film, and polyethylene naphthalate film, and polyolefin films such as polypropylene film. Further, the release layer can be formed from, for example, a composition for forming a release layer. The main component (resin) constituting the release layer forming composition is not particularly limited, and examples thereof include silicone resin, alkyd resin, acrylic resin, and long-chain alkyl resin.

The thickness of the pressure-sensitive adhesive layer can be adjusted according to the coating conditions of the pressure-sensitive adhesive liquid. In order to reduce the thickness of the pressure-sensitive adhesive layer, it is effective to reduce the coating thickness.

In the bonding step, each layer can be bonded by a method in which an adhesive sheet from which one release film has been peeled off is bonded to one layer, then the other release film is peeled off, and the other layer is bonded. It is preferable to apply a surface activation treatment such as a corona treatment to one or both of the bonded surfaces.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these examples. Unless otherwise specified, "%" and "part" in Examples and Comparative Examples are mass% and parts by mass. The physical properties in the following examples were measured by the following methods.

(Manufacturing Example 1: Fabrication of a polarizing plate with a single-sided protective film)
A polyvinyl alcohol film having an average degree of polymerization of about 2400, a saponification degree of 99.9 mol% or more and a thickness of 30 μm is immersed in pure water at 30 ° C., and then the mass ratio of iodine: iodine potassium: water is 0.02: 2: 2: Iodine dyeing was performed by immersing in an aqueous solution of 100 at 30 ° C. (hereinafter, also referred to as an iodine dyeing step). The polyvinyl alcohol film that had undergone the iodine dyeing step was immersed in an aqueous solution at 56.5 ° C. having a mass ratio of potassium iodide: boric acid: water of 12: 5: 100 to perform boric acid treatment (hereinafter, boric acid). Also called a processing process). The polyvinyl alcohol film that had undergone the boric acid treatment step was washed with pure water at 8 ° C. and then dried at 65 ° C. to obtain a polarizer (thickness after stretching: 12 μm) in which iodine was adsorbed and oriented on the polyvinyl alcohol. At this time, stretching was performed in the iodine dyeing step and the boric acid treatment step. The total draw ratio in such stretching was 5.3 times.
A water-based adhesive composed of an aqueous polyvinyl alcohol-based resin solution was applied to one side of the obtained polarizing element, and a protective film (Zeon COP film Zeonoa ZF14) was attached to one side of the polarizing element to obtain a polarizing plate with a single-sided protective film. ..

(Manufacturing Example 2: Preparation of Adhesive Layer (1))
100 parts by mass of monomer component (n-butyl 97.0% by mass, 2-hydroxyethyl acrylate 3.0% by mass) in a reaction vessel equipped with a stirrer, thermometer, reflux condenser, dropping device and nitrogen introduction tube. ), 200 parts by mass of ethyl acetate, and 0.08 parts by mass of 2,2'-azobisisobutyronitrile were charged, and the air in the reaction vessel was replaced with nitrogen gas. The reaction solution was heated to 60 ° C. with stirring under a nitrogen gas atmosphere, reacted for 6 hours, and then cooled to room temperature. By such production, a (meth) acrylic acid ester polymer A having a weight average molecular weight of 1.8 million was obtained.

100 parts by mass of the (meth) acrylic acid ester polymer A obtained in the above step (solid content conversion value; the same applies hereinafter) and trimethyl propane-modified xylylene diisocyanate (manufactured by Mitsui Chemicals, Inc., trade name) as an isocyanate-based cross-linking agent. "Takenate (registered trademark) D-110N") 1.0 part by mass and 3-glycidoxypropyltrimethoxysilane (manufactured by Shinetsu Chemical Industry Co., Ltd., trade name "KBM403") 0.30 as a silane coupling agent A coating solution of the pressure-sensitive adhesive composition was obtained by mixing with parts by mass, stirring thoroughly, and diluting with ethyl acetate.
After applying the coating solution to the release-treated surface (release layer surface) of the separator (manufactured by Lintec Corporation: SP-PLR382190) with an applicator so that the thickness after drying is 20 μm, 1 at 100 ° C. After drying for a minute, another separator (manufactured by Lintec Corporation: SP-PLR38131) is attached to the surface opposite to the surface to which the separator of the adhesive layer is attached, and the adhesive layer with a double-sided separator [adhesive] Layer (1)] was obtained.

(Production Example 3: Preparation of Adhesive Layer (2))
In a reaction vessel equipped with a stirrer, a thermometer, a reflux cooler, a dropping device and a nitrogen introduction tube, 100 parts by mass of a monomer component (n-butyl 98.5% by mass of acrylate, 1.0% by mass of acrylate, 2 acrylate). -Hydroxyethyl 0.5% by mass), 200 parts by mass of ethyl acetate, and 0.08 parts by mass of 2,2'-azobisisobutyronitrile were charged, and the air in the reaction vessel was replaced with nitrogen gas. The reaction solution was heated to 60 ° C. with stirring under a nitrogen gas atmosphere, reacted for 6 hours, and then cooled to room temperature. By such production, a (meth) acrylic acid ester polymer B having a weight average molecular weight of 1.8 million was obtained.

100 parts by mass of the (meth) acrylic acid ester polymer B obtained in the above step (solid content conversion value; the same applies hereinafter) and trimethyl propane-modified tolylene diisocyanate (manufactured by Toso Co., Ltd., trade name "" as an isocyanate-based cross-linking agent. Coronate (registered trademark) L ") 0.30 parts by mass and 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Industry Co., Ltd., trade name" KBM403 ") 0.30 parts by mass as a silane coupling agent. Was mixed, thoroughly stirred, and diluted with ethyl acetate to obtain a coating solution of the pressure-sensitive adhesive composition.
After applying the coating solution to the release-treated surface (release layer surface) of the separator (manufactured by Lintec Corporation: SP-PLR382190) with an applicator so that the thickness after drying is 25 μm, 1 at 100 ° C. After drying for a minute, another separator (manufactured by Lintec Corporation: SP-PLR38131) is attached to the surface opposite to the surface to which the separator of the adhesive layer is attached, and the adhesive layer with a double-sided separator [adhesive] Layer (2)] was obtained.

(Production Examples 4 to 7: Preparation of Adhesive Layers (3) to (6))
In a reaction vessel equipped with a stirrer, a thermometer, a reflux cooler, a dropping device and a nitrogen introduction tube, 100 parts by mass of a monomer component (n-butyl acrylate, 95.0% by mass, 4.0% by mass of acrylate, 2 by mass of acrylate). -Hydroxyethyl 1.0% by mass), 200 parts by mass of ethyl acetate, and 0.08 parts by mass of 2,2'-azobisisobutyronitrile were charged, and the air in the reaction vessel was replaced with nitrogen gas. The reaction solution was heated to 60 ° C. with stirring under a nitrogen gas atmosphere, reacted for 6 hours, and then cooled to room temperature. By such production, a (meth) acrylic acid ester polymer C having a weight average molecular weight of 1.8 million was obtained.

100 parts by mass of the (meth) acrylic acid ester polymer C obtained in the above step (solid content conversion value; the same applies hereinafter) and trimethylolpropane-modified tolylene diisocyanate (manufactured by Toso Co., Ltd., trade name "" as an isocyanate-based cross-linking agent. Coronate (registered trademark) L ") 1.5 parts by mass and 3-glycidoxypropyltrimethoxysilane (manufactured by Shinetsu Chemical Industry Co., Ltd., trade name" KBM403 ") 0.30 parts by mass as a silane coupling agent. , 7.5 parts by mass of ethoxylated isocyanurate triacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd .: product name "A-9300") as an ultraviolet curable compound, and 2-methyl-1- (4-methylthio) as a photopolymerization initiator. Phenyl) -2-morpholinopropan-1-one (BASF: Irgacure (registered trademark) 907) 0.5 parts by mass is mixed, stirred well, and diluted with ethyl acetate to obtain an adhesive. A coating solution of the composition was obtained.
The coating solution is applied to the release-treated surface (release layer surface) of the separator (manufactured by Lintec Corporation: SP-PLR382190) with an applicator so that the thickness after drying is 5 μm, 10 μm, 15 μm, or 25 μm, respectively. Then, it was dried at 100 ° C. for 1 minute, and another separator (manufactured by Lintec Corporation: SP-PLR38131) was attached to the surface opposite to the surface to which the separator of the adhesive layer was attached. ^{This adhesive layer is irradiated with ultraviolet rays (irradiation intensity 500 mW / cm 2} , integrated light intensity 500 mJ / cm ² ) through a release sheet using an ultraviolet irradiation device with a belt conveyor (manufactured by Fusion UV Systems, Inc., a lamp uses a D bulb). Then, an adhesive layer with a double-sided separator was obtained. The pressure-sensitive adhesive layer with a double-sided separator having a thickness of 5 μm is the pressure-sensitive adhesive layer (3), and the pressure-sensitive adhesive layer with a double-sided separator having a thickness of 10 μm is the pressure-sensitive adhesive layer (4) and the thickness of the pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer with a double-sided separator having a thickness of 15 μm is referred to as a pressure-sensitive adhesive layer (5), and the pressure-sensitive adhesive layer with a double-sided separator having a thickness of 25 μm is referred to as a pressure-sensitive adhesive layer (6).

(Production Example 8: Preparation of composition for forming a cured product layer)
The following components were mixed, and the obtained mixture was stirred at 80 ° C. for 1 hour and then cooled to room temperature to obtain a cured product layer forming composition.
-Polymerizable liquid crystal compound LC242 (manufactured by BASF) (19.2% by mass):

-Photopolymerization initiator (0.5% by mass):
Irga Cure (registered trademark) 907 (manufactured by BASF Japan Ltd.)
-Reaction additive (1.1% by mass):
Laromer® LR-9000 (manufactured by BASF Japan Ltd.)
-Solvent (79.1% by mass): Propylene glycol 1-monomethyl ether 2-acetylate

(Production Example 9: Preparation of composition for forming an alignment layer)
As a composition for forming an oriented layer, 15 parts by mass of diethylene glycol di (meth) acrylate (manufactured by Shin-Nakamura Chemical Industry Co., Ltd., A-600) and 1,6-hexanediol di (meth) acrylate (New Nakamura Chemical Industry Co., Ltd.) 15 parts by mass of A-DCP) manufactured by the company and 3.0 parts by mass of Irgacure 907 (manufactured by BASF) as a photopolymerization initiator are dissolved in 70 parts by mass of the solvent methyl ethyl ketone to prepare a composition for forming an alignment layer. bottom.

(Production Example 10: Production of an optically anisotropic layer with a base material layer)
As a base material layer, a polyethylene terephthalate (PET) film having a thickness of 38 μm was prepared. The surface of the base material layer was corona-treated. The corona treatment was performed once using a corona treatment device (AGF-B10, manufactured by Kasuga Electric Works Ltd.) under the conditions of an output of 0.3 kW and a processing speed of 3 m / min. The composition for forming an orientation layer was applied to the corona-treated surface using a bar coater. The coating film was dried at 90 ° C. for 1 minute to obtain an oriented layer on the base material layer (base material layer with an oriented layer). The thickness of the obtained oriented layer was measured with a laser microscope and found to be 2.8 μm.

The composition for forming a cured product layer was applied onto the oriented layer of the base material layer with the oriented layer using a bar coater. The obtained coating film was dried at 90 ° C. for 1 minute. The coating film was irradiated with ultraviolet rays using a high-pressure mercury lamp (Unicure VB-15201BY-A, manufactured by Ushio, Inc.). Ultraviolet irradiation was performed in a nitrogen atmosphere. The wavelength of the ultraviolet rays was 365 nm, and the integrated light intensity at the wavelength of 365 nm was 500 mJ / cm ² . In this way, an optically anisotropic layer with a base material layer was obtained.

(Example 1)
The surface of the polarizing plate with a single-sided protective film obtained in Production Example 1 opposite to the protective film surface was subjected to corona treatment (800 W, 10 m / min, bar width 700 mm, 1 Pass). One separator is peeled off from the pressure-sensitive adhesive layer (1) obtained in Production Example 2, and the corona-treated surface of the polarizing plate with a single-sided protective film and the pressure-sensitive adhesive layer of the pressure-sensitive adhesive layer (1) are bonded to each other to form a single-sided separator. A polarizing plate (I) with an adhesive layer was obtained. Next, the surface of the optically anisotropic layer with a base material layer obtained in Production Example 10 on the cured product layer side is similarly subjected to corona treatment, and then the polarizing plate with an adhesive layer with a single-sided separator (I) is applied to the other. The separator was peeled off and bonded in the same manner as the corona-treated surface of the optically anisotropic layer with a base material layer to obtain a laminated body (I). After peeling off the base material on the cured product layer side of the laminate (I), corona treatment is performed in the same manner, and one separator is peeled off from the pressure-sensitive adhesive layer (1) to form a corona-treated surface and a pressure-sensitive adhesive layer (1). ) Was laminated to obtain a laminate (II). The other separator was peeled off from the laminate (II) and bonded to a non-alkali glass plate (“Eagle-XG” manufactured by Corning Inc.) to prepare an evaluation sample. The evaluation sample was pressurized in an autoclave at a temperature of 50 ° C. and a pressure of 5 MPa for 20 minutes, and then left at a temperature of 23 ° C. and an atmosphere of 60% relative humidity for 1 day. Then, the degree of polarization (Py) was measured using an ultraviolet-visible near-infrared spectrophotometer (V7100, manufactured by JASCO Corporation). Then, after leaving it in an environment of 80 ° C. and 90% humidity for 24 hours, Py was measured in the same manner, and the amount of change in Py (ΔPy) was calculated. The results are shown in Table 1.

(Examples 2 to 5, Comparative Example 1)
Similarly, the degree of polarization (Py) is measured and the amount of change in Py (ΔPy) is calculated, except that the pressure-sensitive adhesive layer (1) of Example 1 is changed to the pressure-sensitive adhesive layers (2) to (6), respectively. Was carried out. The results are shown in Table 1.

(Reference example)
The surface of the polarizing plate with a single-sided protective film prepared above opposite to the protective film surface was subjected to corona treatment (800 W, 10 m / min, bar width 700 mm, 1 Pass). One separator was peeled off from the pressure-sensitive adhesive layer (3) prepared above, and the corona-treated surface of the polarizing plate and the pressure-sensitive adhesive layer were bonded to obtain a polarizing plate (II) with a pressure-sensitive adhesive layer with a single-sided separator. Next, the other separator was peeled off from the polarizing plate (II) with an adhesive layer with a single-sided separator, and then bonded to a non-alkali glass plate (“Eagle-XG” manufactured by Corning Inc.) to prepare an evaluation sample. After that, the evaluation was carried out in the same manner as in Example 1. The results are shown in Table 1.

As shown in Table 1, in Examples 1 to 5, ΔPy was small and the change in the degree of polarization (Py) was suppressed, whereas in Comparative Example 1, ΔPy was large and the degree of polarization (Py) deteriorated. It turned out that it was.

1 Optical laminate, 2 Polarizer, 3 Adhesive layer, 4 Optical anisotropic layer, 10 Polarizing plate with adhesive layer, 11 Protective film, 12 Adhesive layer, 13 Adhesive layer.

Claims (7)

1. An optical laminate having a polarizer, an adhesive layer, and an optically anisotropic layer in this order.
   The optically anisotropic layer is a layer containing a cured product of a composition containing a liquid crystal compound having a polymerizable group and a photopolymerization initiator.
   The photopolymerization initiator comprises a photopolymerization initiator having a base dissociation constant pKb of less than 8.
   The pressure-sensitive adhesive layer contains the resin (A) and contains.
   The pressure-sensitive adhesive layer is an optical laminate satisfying the following formula (1).
   0 ≤ α ≤ 60 (1)
   [In the formula, α represents the product of the content (mass%) of the acid component in all the monomer components constituting the resin (A) and the thickness (μm) of the pressure-sensitive adhesive layer. ]
2. The optical laminate according to claim 1, wherein the content of the acid component in all the monomer components constituting the resin (A) is 0% by mass or more and 1.0% by mass or less.
3. The optical laminate according to claim 1 or 2, wherein the thickness of the pressure-sensitive adhesive layer is 100 μm or less.
4. The optical laminate according to any one of claims 1 to 3, wherein a protective film is provided on the side of the polarizer opposite to the optically anisotropic layer side.
5. A polarizing plate with an adhesive layer, which has the optical laminate according to any one of claims 1 to 4, and further includes an adhesive layer on the side opposite to the polarizer side of the optically anisotropic layer.
6. An image display device including the polarizing plate with an adhesive layer according to claim 5.
7. The method for manufacturing an optical laminate according to claim 1.
   The step of preparing the polarizer,
   A step of curing a composition containing a liquid crystal compound having a polymerizable group and a photopolymerization initiator to form an optically anisotropic layer.
   A method for producing an optical laminate, which comprises a step of forming a pressure-sensitive adhesive layer containing the resin (A) and a step of bonding the polarizer and the optically anisotropic layer via the pressure-sensitive adhesive layer.

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