TW201937213A - Polarizing plate - Google Patents

Abstract

The present invention provides a polarizing plate 100 including a polarizer 11, a first adhesive layer 12, a retardation layer 14, and a second adhesive layer 13 in this order, wherein the value Ta/Tp of the thickness Ta([mu]m) of summation of the the thickness T1([mu]m) of the first adhesive layer 12 and the thickness T2([mu]m) of the second adhesive layer 13 over the total thickness of the polarizing plate Tp([mu]m) is 0.40 or less, and the thickness of the polarizer 11 is 15 [mu]m or less.

Description

Polarizer

The present invention relates to a polarizing plate.

In recent years, image display devices represented by liquid crystal display devices and organic electroluminescence display devices (hereinafter also referred to as organic ELs) have rapidly spread. In the image display device, a polarizing plate having a polarizer and a retardation layer is widely used.

Recently, due to the rise of organic EL, the demand for thinning of the image display device has increased, and the polarizing plate has been required to be thinner. In addition, attention has been paid to the use of a polymerizable liquid crystal compound having high toughness as a raw material of a retardation layer from a conventional retardation film (see, for example, Patent Document 1).

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2017-54093

On the other hand, when trying to reduce the thickness of the polarizing plate, the durability of the polarizing plate is not Full of questions. In particular, when the polarizing plate is exposed to a high-temperature, high-humidity environment, it causes a wrinkle in the polarizing plate.

The wrinkles of the polarizing plate deform the image of the image display device represented by the organic EL. Therefore, the wrinkles of the polarizing plate described above have a problem that the visibility of the image display device is significantly impaired. With the advancement of waterproof technology such as mobile phones, there has been an increase in the use of mobile phones and the like in bathrooms and steam baths in high-temperature and high-humidity environments. Therefore, there is an increasing demand for a polarizing plate having durability in a high-temperature, high-humidity environment.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a polarizing plate which is durable and which is less likely to cause wrinkles even in an environment of high temperature and high humidity.

That is, the present invention has the following constitution.

[1] A polarizing plate comprising, in order, a polarizer, a first adhesive layer, a retardation layer, and a polarizing plate of a second adhesive layer; wherein a thickness T ₁ (μm) of the first adhesive layer is The sum of the thickness T ₂ (μm) of the second adhesive layer, that is, Ta (μm) divided by the total thickness Tp (μm) of the polarizing plate, that is, Ta/Tp is 0.40 or less, and the polarizer The thickness is 15 μm or less.

[2] The polarizing plate according to [1], further comprising an adhesive layer, and comprising the first retardation layer, the adhesive layer, and the second retardation layer in this order.

[3] A polarizing plate comprising, in order, a polarizer, a first adhesive layer, a retardation layer, and a polarizing plate of a second adhesive layer; and a thickness T ₁ (μm) of the first adhesive layer and the foregoing The sum of the thickness T ₂ (μm) of the second adhesive layer and the thickness T ₃ (μm) of the third adhesive layer, that is, Ta' (μm) is obtained by dividing the total thickness Tp' (μm) of the polarizing plate. The value of Ta'/Tp' is 0.40 or less, and the thickness of the polarizer is 15 μm or less.

According to the present invention, it is possible to provide a polarizing plate which is durable even in a high-temperature and high-humidity environment and which is less likely to cause wrinkles.

11‧‧‧ polarizer

12‧‧‧1st adhesive layer

13‧‧‧2nd adhesive layer

14‧‧‧ phase difference layer

15‧‧‧1st phase difference layer

16‧‧‧2nd phase difference layer

17‧‧‧Binder layer or 3rd adhesive layer

100‧‧‧Polar plate

101‧‧‧Polar plate

Fig. 1 is a view showing an example of a schematic cross-sectional view showing a configuration of a polarizing plate of the first embodiment.

Fig. 2 is a view showing an example of a schematic cross-sectional view showing a configuration of a polarizing plate of a second embodiment.

[Formation for implementing the invention]

Hereinafter, a specific embodiment of the polarizing plate of the present invention will be described in detail. The present invention is not limited to the embodiments described below, and various modifications can be made without departing from the spirit and scope of the invention.

[First Embodiment]

<Polarizing plate>

In the present specification, the "polarizing plate" is an optical film including a polarizer and a retardation layer.

The polarizing plate of the first embodiment is provided with a polarizer, a first adhesive layer, a retardation layer, and a second adhesive layer in this order.

Fig. 1 is a view showing an example of a schematic cross-sectional view showing a configuration of a polarizing plate of the first embodiment. As shown in FIG. 1, the polarizing plate 100 is formed by laminating the polarizer 11, the first adhesive layer 12, the retardation layer 14, and the second adhesive layer 13 in this order.

Here, the phase difference layer 14 is, for example, supplied with a layer which supplies a phase difference of λ/2. A layer obtained by laminating a phase difference of λ/4, a positive C layer, and a combination of the layers. The laminated body obtained by the combination includes a laminated body of a layer which supplies a phase difference of λ/2 and a layer which supplies a phase difference of λ/4, a layer which supplies a phase difference of λ/4, and a laminated body of a positive C layer. Etc. as an example.

In the present specification, the term "layer for supplying a phase difference of λ/2" means a phase difference layer for converting a polarization direction of a linearly polarized light of a specific wavelength by 90°.

In the present specification, the term "layer that supplies a phase difference of λ/4" refers to a phase difference layer that converts a linear polarization of a specific wavelength into circularly polarized light (or converts circularly polarized light into linearly polarized light). When the phase difference layer 14 is a layer that supplies a phase difference of λ/4, the polarizing plate 11 including the polarizing plate 11 and the retardation layer 14 can function as a circularly polarizing plate.

In the present specification, the term "positive C layer" means that the refractive index in the slow axis direction in the plane is Nx, and the refractive index in the fast axis direction in the plane is Ny, which is in the thickness direction. When the refractive index is Nz, the layer having a relationship of Nz>Nx≧Ny is satisfied. The difference between the value of Nx and the value of Ny is preferably within 0.5% of the value of Ny, and preferably within 0.3%. Within 0.5%, it can be considered substantially Nx=Ny.

When the polarizing plate having the above configuration is stored in a high-temperature, high-humidity environment, wrinkles are generated. When the inventors of the present invention conducted research, it was also confirmed that the polarizing plate which was wrinkled after storage in a high-temperature and high-humidity environment was deformed. This phenomenon suggests that the stress that causes the phase difference layer to deform in a high-temperature, high-humidity environment acts. The stress which deforms the phase difference layer is considered to be large due to the influence of the adhesive which is in contact with the phase difference layer.

As a result of further study by the inventors of the present invention, it has been found that in the polarizing plate having the above configuration, by controlling the structure of the adhesive layer in contact with the retardation layer, the polarizing plate can be prevented from wrinkles after being maintained in a high-temperature and high-humidity environment. . That is, in the polarizing plate constructed as described above, The present invention has been completed by controlling the configuration of the adhesive which is in contact with the retardation layer, thereby suppressing the stress applied to the retardation layer.

Hereinafter, each layer constituting the polarizing plate 100 of the present embodiment will be described in detail.

<Polarizer>

The polarizing plate 100 of the present embodiment is provided with a polarizing plate 11. In the present specification, the term "polarizing sheet" refers to an optical film having a property of transmitting linearly polarized light having a vibration plane orthogonal to the absorption axis when light having no polarization is incident.

As the polarizer, any appropriate polarizer can be employed. For example, the resin film forming the polarizer may be a single-layer resin film or a two-layer or more laminated film. The polarizer may be a cured film obtained by aligning a dichroic dye to a polymerizable liquid crystal compound and polymerizing the polymerizable liquid crystal compound.

Specific examples of the polarizer composed of a single-layer resin film include a polyvinyl alcohol (hereinafter also abbreviated as PVA) film, a partially methylalized PVA film, and ethylene. The hydrophilic polymer film such as a partially saponified film of a vinyl acetate copolymer is subjected to dyeing treatment using a dichroic substance such as iodine or a dichroic dye, and a product obtained by stretching treatment, and a dehydration treatment of PVA is exemplified. A polyene-based alignment film such as a dechlorination treatment of polyvinyl chloride or the like. Since it has excellent optical characteristics, it is preferable to use a polarizer obtained by dyeing a PVA-based film with iodine and uniaxially extending it.

A polyvinyl alcohol-based resin which is a raw material of a PVA-based film can be produced by saponifying a polyvinyl acetate-based resin. The polyvinyl acetate-based resin can also be a polyvinyl acetate of a homopolymer of vinyl acetate, and a vinyl acetate and copolymerizable with vinyl acetate. Copolymer of other monomers. Examples of the other monomer copolymerizable with vinyl acetate include an unsaturated carboxylic acid, an olefin, a vinyl ether, an unsaturated sulfonic acid, and an acrylamide having an ammonium group.

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

Such a film obtained by forming a polyvinyl alcohol-based resin can also be used as a PVA-based film. The method of forming a film of a polyvinyl alcohol-based resin is not particularly limited, and a film can be formed by a conventional method. The film thickness of the PVA-based film is, for example, about 10 to 100 μm, preferably about 10 to 50 μm.

The thickness of the polarizer is preferably 2 μm or more, and more preferably 3 μm or more. Further, the polarizer has a thickness of 15 μm or less and preferably 12 μm or less. Further, the above upper limit value and lower limit value can be arbitrarily combined.

When the thickness of the polarizer is reduced, the iodine at the end of the polarizer is easily detached in a high-temperature, high-humidity environment. Therefore, the thickness of the polarizer is preferably 2 μm or more. Further, when the thickness of the polarizer is thick, the polarizer is liable to cause cracks in the cold heat exchange test. Since the polarizing plate of the present invention can suppress the stress applied to the retardation layer, it can exhibit excellent durability.

In the present specification, the "thickness of the layer" means the size in the lamination direction of the layer of the polarizing plate. Examples of the "layer" in the present embodiment include a polarizer, an adhesive layer, an adhesive layer, a retardation layer, and a protective film. The thickness of the layer can be obtained, for example, by using a white dry-type non-contact film thickness gauge or using a contact film thickness gauge to measure an arbitrary point of the layer and calculating the average value thereof. Non-contact film thickness measurement enables precise measurement without touching the measurement target. Further, even if the measurement target is a layer of a part of the laminate, the thickness of the measurement target can be performed without peeling off the layers.

When one or both of the areas of the polarizer have a protective film to be described later, the thickness of the polarizer does not include the thickness of the protective film.

The polarizer may have a protective film laminated on one surface or both sides via an adhesive layer or an adhesive layer described later. As the protective film which can be laminated on one surface or both surfaces of the polarizer, for example, a film formed of a thermoplastic resin having excellent transparency, mechanical strength, thermal stability, moisture barrier properties, isotropic properties, and elongation can be used. Specific examples of such a thermoplastic resin include a cellulose resin such as cellulose triacetate, a polyester resin such as polyethylene terephthalate or polyethylene naphthalate, a polyether oxime resin, and a poly Polyamide resin, polyester resin, polyethylene, polypropylene, ethylene, etc. a polyolefin resin such as a propylene copolymer, a cyclic polyolefin resin having a ring system and a norbornene structure (also referred to as a norbornene resin), a (meth)acrylic resin, a polyarylate resin, and a poly A styrene resin, a polyvinyl alcohol resin, and a mixture of such resins.

When the protective film is laminated on both sides of the polarizer, the resin compositions of the two protective films may be the same or different.

The film formed of the thermoplastic resin may be subjected to a surface treatment (for example, corona treatment) or a primer layer in order to improve the adhesion to the polarizer composed of the PVA resin and the dichroic material. A thin layer such as an undercoat layer.

The moisture permeability of the protective film at a temperature of 40 ° C and a humidity of 90% RH is 1 to 1500 g/m ² . 24 hours [hr] is preferred. The moisture permeability of the protective film is greater than 1500 g/m ² . At 24 hr, in a high-temperature and high-humidity environment, the polarizing plate including the protective film is likely to cause wrinkles. The lower the moisture permeability of the protective film, the more remarkable the effect of preventing the occurrence of wrinkles by the polarizing plate including the protective film, and the moisture permeability at a temperature of 40 ° C and a humidity of 90% RH is 1000 g/m ² . It is preferably 24 hr or less, and is 100 g/m ² . Below 24hr is better. The moisture permeability system can be measured in accordance with JIS Z 0208:1976.

The thickness of the protective film is preferably 3 μm or more, and more preferably 5 μm or more. The thickness of the above protection is preferably 50 μm or less, and preferably 30 μm or less. The above upper limit value and lower limit value can be arbitrarily combined.

When the protective film is provided on one or both sides of the polarizer, since the polarizer can be sufficiently reinforced, various durability of the polarizing plate can be further improved.

<1st adhesive layer>

The polarizer and the retardation layer are laminated via the first adhesive layer.

In the present specification, the term "adhesive" means a rubber which is soft and exhibits adhesion by adhering itself to an adherend such as the polarizer or the protective film. The active energy ray-curable adhesive described later is capable of adjusting the adhesion force by irradiating the energy ray.

The adhesive constituting the first adhesive layer is not particularly limited, and a conventionally known adhesive having excellent optical transparency can be used. For example, an acrylic polymer, a urethane polymer, or a polyoxyl oxide can be used. An adhesive for a matrix polymer such as a polymer or a polyvinyl ether polymer. Further, an active energy ray-curing type adhesive, a thermosetting type adhesive, or the like can also be used. Among these adhesives, an acrylic resin having excellent transparency, adhesion, removability (hereinafter also referred to as reworkability), weather resistance, heat resistance, and the like is preferably used as an adhesive for a matrix polymer. . In the present embodiment, the first adhesive layer is composed of a reaction product containing an adhesive composition of a (meth)acrylic resin (1), a crosslinking agent (2), and a decane compound (3). good.

[(Meth)acrylic resin (1)]

In the present embodiment, the (meth)acrylic resin (1) contained in the adhesive composition constituting the first adhesive layer is an alkyl (meth)acrylate derived from the following formula (I). a structural unit (hereinafter also referred to as "structural unit (I)") as a main component (for example, a polymer unit containing 50% by mass or more of the structural unit (I)) (hereinafter also referred to as "(meth)acrylate polymerization) Things") is better.

In the present specification, the term "derived from" means that the chemical structure changes due to polymerization of a compound such as an alkyl (meth)acrylate.

In the formula, R10 represents a hydrogen atom or a methyl group, R20 represents an alkyl group having 1 to 20 carbon atoms, and the alkyl group may have any of a linear, branched or cyclic structure, and the hydrogen of the alkyl group. The atomic system may be substituted with an alkoxy group having 1 to 10 carbon atoms.

In the present specification, the term "(meth)acrylic acid" means either acrylic acid or methacrylic acid. "(Methyl)" such as (meth) acrylate is also the same meaning.

Examples of the (meth) acrylate represented by the formula (I) include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, and isopropyl (meth)acrylate. , n-butyl (meth)acrylate, isobutyl (meth)acrylate, n-amyl (meth)acrylate, n-hexyl (meth)acrylate, isohexyl (meth)acrylate, (meth)acrylic acid Heptyl ester, n-octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n- and isodecyl (meth)acrylate, N-decyl (meth)acrylate, isodecyl (meth)acrylate, n-dodecyl (meth)acrylate, cyclohexyl (meth)acrylate, isodecyl (meth)acrylate, (methyl) Stearyl acrylate, tert-butyl (meth)acrylate, and the like. Specific examples of the alkoxy group-containing alkyl acrylate include 2-methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate. In particular, it is preferable to contain n-butyl (meth)acrylate or 2-ethylhexyl (meth)acrylate, and it is particularly preferable to contain n-butyl (meth)acrylate.

The (meth) acrylate polymer may also contain structural units derived from monomers other than the structural unit (I). The structural unit derived from another monomer may be one type or two or more types. Examples of the other monomer which the (meth) acrylate polymer can contain include a monomer having a polar functional group, a monomer having an aromatic group, and a acrylamide monomer.

Examples of the monomer having a polar functional group include a (meth) acrylate having a polar functional group. Examples of the polar functional group include a hydroxyl group, a carboxyl group, a substituted amino group, and an unsubstituted amino group. Examples of the polar functional group include a heterocyclic group such as an epoxy group.

The content of the structural unit derived from the polar functional group-containing monomer in the (meth) acrylate polymer is preferably 20 parts by mass or less based on 100 parts by mass of the total structural unit of the (meth) acrylate polymer. It is preferably 0.1 parts by mass or more and 20 parts by mass or less, more preferably 0.1 parts by mass or more and 10 parts by mass or less, and particularly preferably 0.5 parts by mass or more and 10 parts by mass or less.

Examples of the monomer having an aromatic group include one (meth)acryl fluorenyl group and one or more aromatic rings (for example, a benzene ring or a naphthalene ring) in the molecule, and a phenyl group or a phenoxy group. Ethyl or benzyl (meth) acrylate. By including these structural units, it is possible to suppress the phenomenon of white spots generated by the polarizing plate in a high-temperature, high-humidity environment.

The content of the structural unit of the aromatic group-derived monomer in the (meth) acrylate polymer is 50% by mass based on 100 parts by mass of the total structural unit of the (meth) acrylate polymer. The amount is preferably hereinafter, preferably 4 parts by mass or more and 50 parts by mass or less, more preferably 4 parts by mass or more and 25 parts by mass or less.

Examples of the acrylamide-based monomer include N-(methoxymethyl)propenylamine, N-(ethoxymethyl)acrylamide, and N-(propoxymethyl)acrylamide. N-(butoxymethyl) acrylamide, N-(2-methylpropoxymethyl) acrylamide, and the like. By containing these structural units, it is possible to suppress the bleeding of an additive such as an antistatic agent described later.

Further, the structural unit derived from a monomer other than the structural unit (I) may further contain a structural unit derived from a styrene monomer, a structural unit derived from a vinyl monomer, and a source derived from a molecule. A plurality of structural units of (meth)acrylonitrile groups and the like.

The weight average molecular weight (hereinafter also referred to as "Mw") of the (meth)acrylic resin (1) is preferably from 500,000 to 2,500,000. When the weight average molecular weight is 500,000 or more, the durability of the first adhesive layer in an environment of high temperature and high humidity can be improved. When the weight average molecular weight is 2.5 million or less, the workability in coating the coating liquid containing the adhesive composition is good. The ratio of the weight average molecular weight (Mw) to the number average molecular weight (hereinafter also referred to as "Mn") indicates a molecular weight distribution (Mw/Mn) of usually 2 to 10. In the present specification, the "weight average molecular weight" and the "number average molecular weight" are polystyrene-converted values measured by a gel permeation chromatography (GPC) method.

When the (meth)acrylic resin (1) is dissolved in ethyl acetate to a solution having a concentration of 20% by mass, the viscosity at 25 ° C is 20 Pa. The following is better, from 0.1 to 15Pa. s is preferred. When the viscosity of the (meth)acrylic resin (1) at 25 ° C is within the above range, it contributes to durability improvement and rework of the polarizing plate including the first adhesive layer formed using the above resin. . The aforementioned viscosity can be measured using a Brookfield viscometer.

The glass transition temperature of the (meth)acrylic resin (1) is preferably from -60 ° C to -10 ° C from the viewpoint of cohesiveness and durability. Further, the glass transition temperature can be measured using a differential scanning calorimeter (DSC).

The (meth)acrylic resin (1) may contain two or more kinds of (meth)acrylate polymers. As such a (meth) acrylate polymer, for example, a lower molecular weight (meth)acrylic acid having a structural unit (I) as a main component and having a weight average molecular weight of, for example, 50,000 to 300,000 is exemplified. Ester polymer.

[Crosslinking agent (2)]

The adhesive composition forming the first adhesive layer preferably contains the crosslinking agent (2). Examples of the crosslinking agent (2) include a usual crosslinking agent (isocyanate compound, epoxy compound, anthracycline compound, metal clamp compound, peroxide, etc.), particularly from the viewpoint of an adhesive composition. From the viewpoints of the period, the crosslinking speed, and the durability of the polarizing plate, an isocyanate compound is preferred.

The isocyanate-based compound is preferably a compound having at least two isocyanato groups (-NCO) in the molecule, and examples thereof include an aliphatic isocyanate compound (for example, hexamethylene diisocyanate) and an alicyclic group. Isocyanate-based compound (for example, isophorone diisocyanate), hydrogenated dimethylenedi-isocyanate, hydrogenated diphenylmethane diisocyanate, aromatic isocyanate-based compound (for example, toluene diisocyanate, benzodimethylisocyanate, diphenyl) Methane diisocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate, etc.). The crosslinking agent (2) may be an adduct (addition) obtained by using a polyhydric alcohol compound (for example, an adduct obtained by glycerin or trimethylolpropane), or the like. Isocyanate compound and isomeric cyanurate compound, biuret type compound, polyether polyol, polyester polyol, acrylic acid A derivative of a urethane prepolymer type isocyanate compound obtained by addition reaction of a polyhydric alcohol, a polybutadiene polyol, or a polyisoprene polyol. The crosslinking agent (2) can be used singly or in combination of two or more. Among these compounds, from the viewpoint of durability, toluene diisocyanate, benzodimethyl diisocyanate, hexamethylene diisocyanate, and a polyol compound of the diisocyanate or a hetero-isocyanate of the diisocyanate A polycyanate compound is preferred.

The ratio of the crosslinking agent (2) may be, for example, 0.01 to 10 parts by mass, preferably 0.1 to 3 parts by mass, more preferably 0.1 to 1 part by mass, per 100 parts by mass of the (meth)acrylic resin (1). . When it is at most the above upper limit value, it is advantageous for improving durability, and when it is at least the above lower limit value, it is advantageous for suppressing generation of gas and improving reworkability.

[decane compound (3)]

The adhesive composition can contain a decane compound (3). By containing the decane compound (3), the adhesion of the first adhesive layer to the layer of the first adhesive layer can be improved. Two or more kinds of decane compounds (3) can also be used.

Examples of the decane compound (3) include vinyltrimethoxydecane, vinyltriethoxydecane, vinyl ginseng (2-methoxyethoxy)decane, and 3-glycidoxypropyltrimethyl. Oxydecane, 3-glycidoxypropyltriethoxydecane, 3-glycidoxypropylmethyldimethoxydecane, 3-glycidoxypropylethoxydimethyl Baseline, 2-(3,4-epoxycyclohexyl)ethyltrimethoxydecane, 3-chloropropylmethyldimethoxydecane, 3-chloropropyltrimethoxydecane, 3-methylpropane醯oxypropyltrimethoxydecane, 3-hydrothiopropyltrimethoxydecane, and the like.

As the decane compound (3), an oligomer derived from the compound shown in the above examples can be contained.

The content of the decane compound (3) in the adhesive composition is usually 0.01 to 10 parts by mass, preferably 0.03 to 5 parts by mass, per 100 parts by mass of the (meth)acrylic resin (1), preferably It is 0.05 to 2 parts by mass, more preferably 0.1 to 1 part by mass. When the content of the decane compound (3) is 0.01 parts by mass or more, the adhesion between the first adhesive layer and the adherend is easily improved. When the content is 10 parts by mass or less, the decane compound (3) can be prevented from oozing out from the first adhesive layer.

[Other ingredients (4)]

The adhesive composition forming the first adhesive layer can contain two or more kinds of ultraviolet absorbers, antistatic agents, solvents, cross-linking catalysts, adhesion-imparting resins (tackifiers), plasticizers, and the like. Additives. Further, it is also useful to form a first adhesive layer by blending an ultraviolet curable compound with an adhesive composition, and then irradiating with ultraviolet rays to be hardened to form a hard adhesive layer.

The thickness of the first adhesive layer is preferably 3 μm or more, and more preferably 5 μm or more. Further, the thickness of the first adhesive layer is preferably 40 μm or less, and preferably 30 μm or less. Further, the above upper limit value and lower limit value can be arbitrarily combined.

When the thickness of the first adhesive layer is at least the above lower limit value, the polarizer and the retardation layer can be sufficiently bonded. When the thickness of the first adhesive layer is equal to or less than the above upper limit value, the retardation layer is less likely to be displaced, and the effect of suppressing wrinkles of the polarizing plate due to deformation of the retardation layer is suppressed.

When the laminated body of the present embodiment is produced, when the polarizer is bonded to the retardation layer via the first adhesive while using a strong pressure, the first adhesive layer is bonded to the weaker pressure. The thickness of the thickness is thinned. This is because the first adhesive layer has stretchability. However, when the polarizer is bonded to the retardation layer, if it is temporarily placed, the thickness of the first adhesive layer is restored. Therefore, the polarizer is attached to the phase difference layer with a strong pressure through the first adhesive. In time, for example, the thickness of the first adhesive layer can be measured after standing for 5 minutes to obtain a constant value.

<2nd adhesive layer>

The second adhesive layer layer is a surface on the opposite side of the surface of the retardation layer that is in contact with the first adhesive layer. The polarizing plate is laminated on the display panel or the like via a second adhesive layer.

As the adhesive constituting the second adhesive layer used for the laminate of the retardation layer and, for example, a display panel, the conventionally known adhesive having excellent optical transparency can be used without particular limitation.

As the adhesive constituting the second adhesive layer, the same as those exemplified as the adhesive constituting the first adhesive layer can be used. The thickness of the first adhesive layer and the second adhesive layer may be the same or different.

As the adhesive for the second adhesive layer, an active energy ray-curable adhesive can also be used. The "active energy ray-curing type adhesive" has a property of being cured by irradiation with an energy ray such as an ultraviolet ray or an electron ray. Since the active energy ray-curable adhesive has adhesiveness even before the irradiation of the energy ray, it is adhered to the adherend such as a film and has a property of being hardened by irradiation with an energy ray to adjust the adhesion. Agent. In the present embodiment, the adhesive used in the second adhesive layer is preferably an active energy ray-curable adhesive, and among them, an ultraviolet-curable adhesive is preferred.

The active energy ray-curable adhesive usually contains an acrylic adhesive and an energy ray polymerizable compound as a main component. A crosslinking agent is usually further formulated, and a photopolymerization initiator, a photosensitizer, or the like can be formulated as necessary.

When the phase difference layer is bonded to, for example, a display panel by using an active energy ray-curable adhesive, the phase difference is first laminated on the display panel via an active energy ray-curable adhesive. Next, the active energy rays such as ultraviolet rays, visible rays, electron rays, and X rays are irradiated to cure the adhesive layer composed of the active energy ray-curable adhesive. As the active energy ray, ultraviolet ray is preferred. As the light source at this time, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a chemical lamp, a black light lamp, a microwave excited mercury lamp, a halogenated metal lamp, or the like can be used.

The thickness of the second adhesive layer is preferably 3 μm or more, and more preferably 5 μm or more. Further, the thickness of the second adhesive layer is preferably 40 μm or less, more preferably 30 μm or less, and may be 22 μm or less. Further, the above upper limit value and lower limit value can be arbitrarily combined.

When the thickness of the second adhesive layer is at least the above lower limit value, the retardation layer can be sufficiently bonded to, for example, a display panel or the like.

When the thickness of the second adhesive layer is equal to or less than the above upper limit value, the retardation layer laminated between the second adhesive layer and the display panel is less likely to be displaced. Therefore, the phase difference layer can be firmly fixed and the polarizer and the phase difference layer are not easily offset. As a result, the effect of suppressing wrinkles of the polarizing plate due to deformation of the retardation layer is suppressed. The thickness of the second adhesive layer may also be greater than the thickness of the first adhesive layer.

When the laminated body of the present embodiment is produced, when the retardation layer is bonded to the display panel or the like with a strong pressure via the second adhesive, the second adhesive is bonded to the pressure when the pressure is applied to a weaker pressure. The thickness of the layer is thinned. This is because the second adhesive layer is stretched. However, when the retardation layer is bonded to, for example, a display panel or the like, the thickness of the second adhesive layer is restored as it is. Therefore, using a strong pressure to separate the phase through the second adhesive When the difference layer is bonded to a display panel or the like, for example, the thickness of the second adhesive layer can be measured after standing for 5 minutes to obtain a constant value.

In one aspect of the embodiment, a polarizing plate is used, and a sum of a thickness T ₁ (μm) of the first adhesive layer and a thickness T ₂ (μm) of the second adhesive layer, that is, Ta (μm) The value obtained by dividing the total thickness Tp (μm) of the polarizing plate, that is, Ta/Tp is 0.40 or less, and Ta (μm) is the thickness T ₁ (μm) of the first adhesive layer and the second adhesive layer. The sum of the thicknesses T ₂ (μm).

The Ta/Tp is preferably 0.10 or more, more preferably 0.20 or more, and still more preferably 0.25 or more. The Ta/Tp0 is preferably 0.38 or less. The above upper limit value and lower limit value can be arbitrarily combined.

When Ta/Tp is at most the above upper limit value, the phase difference layer is less likely to be displaced, and the effect of suppressing wrinkles of the polarizing plate due to deformation of the retardation layer is suppressed. This is because the ratio of the adhesive layer occupied by the polarizing plate is not more than a certain value, and it is possible to form a layer structure that does not easily pass through water vapor.

The value of Ta/Tp can be adjusted by adjusting the thickness of the layer constituting the polarizing plate. It is effective to reduce the thickness of the first adhesive layer and the thickness of the second adhesive layer while ensuring a certain total thickness of the polarizing plate.

In the present specification, the term "the total thickness of the polarizing plate" means the dimension of the direction in which the polarizing plate is laminated. In other words, the "total thickness of the polarizing plate of the first embodiment" means the thickness of the polarizer, the thickness of the first adhesive layer, the thickness of the retardation layer, and the thickness of the second adhesive layer. The thickness of all the optical film layers, the adhesive layer, and the adhesive layer included in the other polarizing plates is a total thickness. The total thickness of the polarizer does not contain the last remaining in the display The components of the device. As a member which does not remain in the display device at the end, a surface protective film which is laminated on the surface of the polarizing plate opposite to the display panel, and a separator which is laminated on the second adhesive layer are exemplified. These layers are peeled off during the manufacturing process of the display device and remain in the display device at the end.

The total thickness of the polarizing plate can be obtained, for example, by measuring any five points of the polarizing plate using a micrometer and calculating the average value thereof.

The total thickness of the polarizing plate can be measured by the thickness of the polarizer, the thickness of the first adhesive layer, the thickness of the retardation layer, the thickness of the second adhesive layer, and all the optical films included in other polarizing plates. The thickness of the layer, the adhesive layer, and the adhesive layer is obtained by summing the value layers.

The thickness of the polarizer, the thickness of the first adhesive layer, the thickness of the retardation layer, the thickness of the second adhesive layer, and the thickness of all the optical film layers, the adhesive layer, and the adhesive layer included in the other polarizing plates can be used. Measured by the method described in the manual.

The total thickness of the polarizing plate of the first embodiment is preferably 30 μm or more. Further, the total thickness of the polarizing plate is preferably 300 μm or less, more preferably 200 μm or less, and still more preferably 150 μm or less. Further, the above upper limit value and lower limit value can be arbitrarily combined.

When the total thickness of the polarizing plate is equal to or less than the above upper limit value, it is possible to contribute to thinning of the polarizing plate. When the total thickness of the polarizing plate is equal to or higher than the above lower limit value, the strength of the polarizing plate is improved.

The water vapor permeability of the first adhesive layer and the second adhesive layer at a temperature of 40 ° C and a humidity of 90% is each in the range of 1,000 to 10,000 g/m ² . 24h is preferred, and may be 2,000 to 9,000 g/m ² . 24h. The water vapor permeability can be measured using a Lyssy water vapor permeability meter L80 Series manufactured by Systech ILLINOIS. When the water vapor permeability of the adhesive layer is high, since the adhesive is strongly affected by the high temperature and high humidity environment, it is easy to cause wrinkles in the polarizing plate due to deformation of the retardation layer. When it is not easy to measure the water vapor permeability of the adhesive monomer, it can also be calculated by laminating the adhesive on a substrate having a high moisture permeability and from a ratio of a substrate having a high moisture permeability. Water vapor penetration.

<phase difference layer>

The retardation layer 14 has a layer composed of a liquid crystal material (also referred to as a liquid crystal composition) containing a liquid crystal compound. The layer composed of a liquid crystal material containing a liquid crystal compound specifically means a layer obtained by hardening a liquid crystal compound. In the present specification, a layer that supplies a phase difference of λ/2, a layer that supplies a phase difference of λ/4, and a positive C layer are collectively referred to as a phase difference layer. Further, the retardation layer may include a transparent substrate and an alignment layer to be described later.

The layer obtained by hardening the liquid crystal compound is formed, for example, on the alignment layer provided on the transparent substrate. The term "transparent substrate" refers to a substrate that is capable of transmitting light, particularly having transparency that is capable of transmitting visible light. In the present specification, the term "transparency" means a characteristic that the transmittance of light in a visible light region having a wavelength in the range of 380 to 780 nm is 80% or more.

The transparent substrate may also be a substrate having a function of supporting an alignment layer and forming a strip. This transparent substrate can function as a release-supporting body and supports a phase difference layer for transfer. Moreover, it is preferable that the surface thereof has an adhesive force to the extent that it can be peeled off.

The transparent substrate may, for example, be a glass substrate or a plastic substrate, and is preferably a plastic substrate. Examples of the plastic constituting the plastic substrate include polyolefins such as polyethylene, polypropylene, and decene-based polymers, cyclic olefin resins, polyvinyl alcohol, polyethylene terephthalate, and polymethylation. Acrylate, polyacrylate, cellulose triacetate, cellulose diacetate and A cellulose ester such as cellulose acetate propionate, polyethylene naphthalate, polycarbonate, polyfluorene, polyether oxime, polyether ketone, polyphenylene sulfide, and polyphenylene ether. In particular, a cellulose ester, a cyclic olefin resin, polyethylene terephthalate or polymethacrylate is particularly preferable in that it can be easily obtained from the market or has excellent transparency. The transparent substrate may be a single layer composed of these materials, or may be a laminate having two or more layers. Further, when a laminate of a plurality of layers is used, a layer having the same composition may be laminated.

The thickness of the transparent substrate is not particularly limited, and is preferably in the range of, for example, 20 μm or more and 200 μm or less. When the thickness of the transparent substrate is 20 μm or more, strength can be imparted. On the other hand, when the thickness is 200 μm or less, when the transparent substrate is cut into a single transparent substrate, the increase in the machining chips and the abrasion of the cutting edge can be suppressed.

Transparent substrates can also be subjected to various anti-caking treatments. Examples of the anti-caking treatment include a treatment which is easy to carry out, a mixture of fillers, and the like, and an embossing process (knurling process). By performing such an anti-caking treatment on the transparent substrate, it is possible to effectively prevent the occurrence of agglomeration between the substrates when the transparent substrate is wound up, that is, so-called agglomeration, and to produce the optical film with high productivity.

The layer obtained by hardening the liquid crystal compound is formed on the transparent substrate via the alignment layer. That is, the retardation layer sequentially laminates the transparent substrate and the alignment layer and laminates the liquid crystal compound on the alignment layer.

The alignment layer is not limited to the vertical alignment layer, and may be an alignment layer in which the molecular axes of the liquid crystal compound are aligned horizontally, or an alignment layer in which the molecular axes of the liquid crystal compound are obliquely aligned. The film having the solvent resistance which is not dissolved by coating or the like with a liquid crystal compound coating liquid to be described later is used as the alignment film, and the solvent is removed and the alignment of the liquid crystal compound is heat-treated. A film having heat resistance is preferred. Examples of the alignment film include an alignment film containing an alignment polymer, a groove alignment film in which a concave-convex pattern and a plurality of grooves are formed on the photo-alignment film and the surface, and the grooves are aligned. The thickness of the alignment film is usually in the range of 10 nm to 10000 nm, preferably in the range of 10 nm to 1000 nm, preferably 500 nm or less, more preferably in the range of 10 nm to 200 nm.

The resin to be used in the alignment layer is not particularly limited as long as it is a material used as a material of the conventional alignment film, and a conventionally known monofunctional or polyfunctional (meth)acrylate monomer can be used. A cured product obtained by hardening under a polymerization initiator. Specifically, examples of the (meth) acrylate monomer include 2-ethylhexyl acrylate, cyclohexyl acrylate, diethylene glycol mono 2-ethylhexyl acrylate, and diethylene glycol. Monophenyl ether acrylate, tetraethylene glycol monophenyl ether acrylate, trimethylolpropane triacrylate, lauryl acrylate, lauryl methacrylate, isodecyl acrylate, isodecyl methacrylate, acrylic acid 2-phenoxyethyl ester, tetrahydrofurfuryl acrylate, 2-hydroxypropyl acrylate, benzyl acrylate, tetrahydrofurfuryl methacrylate, 2-hydroxypropyl methacrylate, benzyl methacrylate, methyl Cyclohexyl acrylate, methacrylic acid, urethane acrylate, and the like. Further, the resin may be one type or a mixture of two or more types.

The type of the liquid crystal compound used in the present embodiment is not limited, but can be classified into a rod-shaped (rod-like liquid crystal compound) and a disk-shaped type (a discotic liquid crystal compound or a discotic liquid crystal compound) from the shape thereof. . Moreover, each has a low molecular type and a high molecular type. In addition, the term "polymer" generally refers to a substance having a degree of polymerization of 100 or more (polymer physics, phase transfer power, Dou Masaru, page 2, Iwanami Shoten, 1992).

In the present embodiment, any liquid crystal compound can be used. Further, two or more kinds of rod-like liquid crystal compounds, two or more kinds of discotic liquid crystal compounds, or rods may be used. A mixture of a liquid crystal compound and a discotic liquid crystal compound.

For example, the compound described in the above paragraphs [0026] to [0098] of the Japanese Patent Application Laid-Open No. Hei No. Hei. As the discotic liquid crystal compound, for example, a compound described in paragraphs [0020] to [0067] of JP-A-2007-108732 or paragraphs [0013] to [0108] of JP-A-2010-244038 can be suitably used.

The layer obtained by curing the liquid crystal compound is preferably formed by using a rod-like liquid crystal compound having a polymerizable group or a discotic liquid crystal compound having a polymerizable group. Thereby, temperature change and humidity change of optical characteristics can be reduced.

Two or more types of liquid crystal compounds may be used in combination. In this case, it is preferred to have two or more polymerizable groups in the molecule in at least one type. In other words, the layer obtained by curing the liquid crystal compound is preferably a layer in which a rod-like liquid crystal compound having a polymerizable group or a discotic liquid crystal compound having a polymerizable group is fixed by polymerization and formed. At this time, it is not necessary to display liquid crystallinity after the layer is formed.

When the rod-like liquid crystal compound or the discotic liquid crystal compound has a polymerizable group, the type of the polymerizable group is not particularly limited. The polymerizable group is preferably a functional group capable of undergoing polymerization reaction such as a polymerizable ethylenically unsaturated group or a cyclopolymerizable group. More specifically, examples of the polymerizable group include a (meth)acryl fluorenyl group, a vinyl group, a styryl group, and an allyl group. Among them, a (meth) acrylonitrile group is preferred. Moreover, the (meth) acrylonitrile group is a concept including both a methacryl fluorenyl group and an acryl fluorenyl group.

The layer obtained by hardening the liquid crystal compound can be formed by applying a liquid crystal compound-containing coating liquid onto, for example, an alignment layer as described later. The coating liquid may also contain the above liquid crystal Ingredients other than the compound. The coating liquid may also contain a polymerization initiator. The polymerization initiator used can be selected, for example, as a thermal polymerization initiator and a photopolymerization initiator in the form of a polymerization reaction. Examples of the photopolymerization initiator include an α-carbonyl compound, a acyloin ether, an α-hydrocarbon-substituted aromatic oxime compound, a polynuclear benzoquinone compound, a triaryl imidazole dimer, and a p-amino group. Combination of phenyl ketone and the like. The polymerization initiator is preferably used in an amount of from 0.01 to 20% by mass, preferably from 0.5 to 5% by mass, based on the total solid content of the coating liquid.

The coating liquid may contain a polymerizable monomer in terms of uniformity of the coating film and film strength. Examples of the polymerizable monomer include a radical polymerizable or cationically polymerizable compound. Among them, a polyfunctional radical polymerizable monomer is preferred.

The polymerizable monomer is preferably a compound which can be copolymerized with the above-mentioned liquid crystal compound having a polymerizable group (hereinafter also referred to as a polymerizable liquid crystal compound). Specific examples of the polymerizable monomer include those described in paragraphs [0018] to [0020] of JP-A-2002-296423. The amount of the polymerizable monomer to be used is preferably from 1 to 50% by mass, and preferably from 2 to 30% by mass, based on the total mass of the liquid crystal compound.

The coating liquid may contain a surfactant in terms of uniformity of the coating film and film strength. As the surfactant, a conventionally known compound can be mentioned. Among them, fluorine-based compounds are particularly preferred. Specific examples of the surfactants include the compounds described in paragraphs [0028] to [0056] of JP-A-2001-330725, and paragraphs [0069] to [0126 in the specification of Japanese Patent Application No. 2003-295212. The compound described.

The coating liquid may contain a solvent and an organic solvent can be suitably used.

Examples of the organic solvent include decylamine (for example, N,N-dimethylformamide), hydrazine (for example, dimethyl hydrazine), heterocyclic compound (for example, pyridine), and hydrocarbon (for example, benzene and hexane). ), alkyl halides (example Such as chloroform, dichloromethane), esters (such as methyl acetate, ethyl acetate, butyl acetate), ketones (such as acetone, methyl ethyl ketone), ethers (such as tetrahydrofuran, 1,2-dimethoxy B) alkyl). Among them, an alkyl halide or a ketone is preferred. Two or more types of organic solvents may be used in combination as the coating liquid.

The coating liquid may have a vertical alignment accelerator such as a polarizer interfacial side vertical alignment agent or an air interface side vertical alignment agent, and a horizontal alignment accelerator such as a polarizer interface side horizontal alignment agent and an air interface side horizontal alignment agent. Various alignment agents. Further, the coating liquid may contain a adhesion improving agent, a plasticizer, a polymer or the like in addition to the above components.

In the present embodiment, the thickness of the phase difference layer is preferably 0.5 μm or more. The thickness of the retardation layer is preferably 10 μm or less, and more preferably 5 μm or less. The above upper limit value and lower limit value can be arbitrarily combined.

When the thickness of the retardation layer is at least the above lower limit value, sufficient durability can be obtained. When the thickness of the phase difference layer is equal to or less than the above upper limit value, it is possible to contribute to thinning of the polarizing plate.

The thickness of the phase difference layer can be such that a layer that supplies a phase difference of λ/4, a layer that supplies a phase difference of λ/2, or an in-plane phase difference value of the positive C layer, and a phase difference in the thickness direction can be obtained. The way to adjust.

The moisture permeability ratio of the retardation layer at a temperature of 40 ° C and a humidity of 90% RH is preferably in the range of 0.5 to 1.0. The moisture permeability ratio refers to a value calculated by the following method. Since the thickness and mechanical properties of the phase difference layer are low, it is difficult to measure the moisture permeability. Therefore, the phase difference layer is bonded to the substrate having high moisture permeability through the adhesive, and the moisture permeability is measured. The measurement of the moisture permeability can be carried out by the same method as the measurement of the moisture permeability of the protective film. The moisture permeability ratio is calculated by the ratio of the measured moisture permeability to the moisture permeability of the substrate.

The lower the moisture permeability ratio, the more effective it is to suppress wrinkles in a high-temperature, high-humidity environment.

[Second Embodiment]

The polarizing plate of the second embodiment is provided with a polarizer, a first adhesive layer, a first retardation layer, an adhesive layer or a third adhesive layer, a second retardation layer, and a second adhesive layer in this order. Polarizer. That is, the polarizing plate of the second embodiment includes at least two retardation layers.

Fig. 2 is a view showing an example of a schematic cross-sectional view showing a configuration of a polarizing plate of a second embodiment. As shown in FIG. 2, the polarizing plate 101 is sequentially laminated with a polarizer 11, a first adhesive layer 12, a first retardation layer 15, an adhesive layer or a third adhesive layer 17, and a second retardation layer 16, And the second adhesive layer 13.

In addition, the components (the polarizer 11, the first adhesive layer 12, and the second adhesive layer 13) which are the same as those of the above-described first embodiment are denoted by the same reference numerals and will not be described.

<Laminated body including two layers of phase difference layers>

The first retardation layer 15 and the second retardation layer 16 are laminated via an adhesive layer or a third adhesive layer 17 . Each of the first retardation layer 15 and the second retardation layer 16 can be a layer that supplies a phase difference of λ/2, a layer that supplies a phase difference of λ/4, or a positive C layer. As one aspect of the present embodiment, it is preferable that either of the first retardation layer 15 and the second retardation layer 16 functions as a layer for supplying a phase difference of λ/4, and the other is a supply λ. a function of a layer of phase difference of /2; or either of the first retardation layer 15 and the second retardation layer 16 is a layer that supplies a phase difference of λ/4, and the other is a positive C layer. Features. Therefore, the thickness of the first retardation layer 15 and the second retardation layer 16 and the material constituting the layers are such that a layer that supplies a phase difference of λ/4, a layer that supplies a phase difference of λ/2, or The in-plane phase difference and the phase difference in the thickness direction required for the positive C layer are adjusted in such a manner.

The first retardation layer 15 functions as a layer that supplies a phase difference of λ/2, and the second retardation layer 16 functions as a layer that supplies a phase difference of λ/4, and the thickness of the first retardation layer 15 For example, the thickness of the second retardation layer 16 is, for example, 1 μm or more and 10 μm or less. When the first retardation layer 15 functions as a layer that supplies a phase difference of λ/4, and the second retardation layer 16 functions as a positive C layer, the thickness of the first retardation layer 15 is, for example, 1 μm or more and 10 μm. Hereinafter, the thickness of the second retardation layer 16 is, for example, 1 μm or more and 10 μm or less.

The transparent substrate, the alignment layer, and the liquid crystal compound used for forming the first retardation layer and the second retardation layer can be the same as those exemplified in the first embodiment. The composition of the first retardation layer and the second retardation layer may be the same or different. The respective thicknesses of the first retardation layer and the second retardation layer can be obtained by using the measurement method of the layer thickness described in the first embodiment.

Each of the first retardation layer and the second retardation layer is formed in the same manner as the retardation layer of the first embodiment, and the transparent substrate, the alignment layer, and the retardation layer are sequentially laminated. The transparent substrate and the alignment layer may also be peeled off. The first retardation layer and the second retardation layer are formed by laminating an adhesive layer or a third adhesive. In other words, the polarizing plate of the second embodiment includes a laminate in which the first retardation layer, the adhesive layer, the third adhesive layer, and the second retardation layer are laminated in this order.

The polarizing plate of the second embodiment preferably includes a first retardation layer, an adhesive layer, and a second retardation layer in this order.

In the present specification, the "adhesive" constituting the adhesive layer can be applied to the substrate in a liquid form when applied to a substrate, and can be cured by curing to form an adhesive property (that is, until hardening). Those who do not show continuity.

More specifically, the term "adhesive agent" means a material having a glass transition temperature (Tg) of 25 ° C or more when the member to be joined is followed. On the other hand, the term "adhesive" means a glass transition temperature (Tg) at which the adhesion between the members to be adhered is less than 25 °C.

<Binder layer>

Examples of the adhesive that bonds the first retardation layer and the second retardation layer include a water-based adhesive and an active energy ray-curable adhesive. The water-based adhesive agent is, for example, an adhesive obtained by dissolving or dispersing a polyvinyl alcohol-based resin in water. The active energy ray-curable adhesive agent is, for example, an adhesive containing a curable compound which is cured by irradiation with an active energy ray such as ultraviolet rays, visible light, electron rays, or X-rays. The storage elastic modulus of the active energy ray-curable adhesive after hardening is mostly higher than the storage elastic modulus of the aqueous adhesive. When the storage elastic modulus of the adhesive layer between the retardation layers as the index indicating the hardness is high, the retardation layers are less likely to be displaced, so that it is preferable to use an active energy ray-curable adhesive.

As the active energy ray-curable adhesive, it is preferred to contain either or both of a cationically polymerizable curable compound and a radically polymerizable curable compound in order to exhibit good adhesion. The active energy ray-curable adhesive may further contain either or both of a cationic polymerization initiator and a radical polymerization initiator to initiate a curing reaction of the curable compound.

Examples of the cationically polymerizable curable compound include an epoxy compound (a compound having one or two or more epoxy groups in the molecule) and an oxetane compound (having a molecule in the molecule). a compound of one or two or more oxetane rings), or a combination of such compounds.

Examples of the radically polymerizable curable compound include a (meth)acrylic compound (a compound having one or two or more (meth)acrylenyloxy groups in the molecule) and a radical polymerizable property. Other vinyl compounds of double bonds, combinations of such compounds, and the like.

The active energy ray-curable adhesive can contain a cationic polymerization accelerator, an ion scavenger, an antioxidant, a chain transfer agent, an adhesion-imparting agent, a thermoplastic resin, a filler, a flow regulator, a plasticizer, and an antifoaming agent as necessary. Additives such as antistatic agents, leveling agents, solvents, etc.

When the first retardation layer and the second retardation layer are bonded together by using an adhesive, first, the adhesive is applied to the joint surface of either the first retardation layer and the second retardation layer, or both. Joint surface.

As a method of applying an adhesive to the above-mentioned joint surface, a die coater, a comma coater, a reverse roll coater, a gravure coater, a bar coater, and a wire bar are used. A general coating technique such as a cloth, a blade coater, or a pneumatic blade coater can be used.

The drying method in the case of using a water-based adhesive is not particularly limited, and for example, a method of drying using a hot air dryer and an infrared dryer can be employed.

On the other hand, when an active energy ray-curable adhesive is used, an active energy ray-curable adhesive such as ultraviolet rays, visible light, electron rays, and X-rays is irradiated to cure the active energy ray-curable adhesive. As the active energy ray, ultraviolet ray is preferred. As the light source at this time, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a chemical lamp, a black light lamp, a microwave excited mercury lamp, a halogenated metal lamp, or the like can be used.

The thickness of the subsequent layer is preferably 10 μm or less, and more preferably 5 μm or less.

When the thickness of the subsequent layer is equal to or less than the above upper limit, the first retardation layer and the second phase difference are It is not easy to cause floating and peeling between layers.

A value obtained by dividing Ta (μm) by the total thickness Tp (μm) of the polarizing plate, in which the first retardation layer and the second retardation layer are laminated via the adhesive layer. That is, a polarizing plate having a Ta/Tp of 0.40 or less, and Ta (μm) is a sum of a thickness T ₁ (μm) of the first adhesive layer and a thickness T ₂ (μm) of the second adhesive layer.

The Ta/Tp is preferably 0.10 or more, more preferably 0.20 or more, and still more preferably 0.25 or more. Further, the Ta/Tp is preferably 0.38 or less. The above upper limit value and lower limit value can be arbitrarily combined.

When Ta/Tp is equal to or less than the above upper limit value, the retardation layer is less likely to be displaced, and the effect of suppressing wrinkles of the polarizing plate due to deformation of the retardation layer is suppressed.

The value of Ta/Tp described above can be reduced by increasing the value of Tp or decreasing the value of Ta. However, since it is difficult to manufacture a thin polarizing plate when the value of Tp becomes large, the value of Ta is preferably reduced. In other words, it is effective to reduce the thickness of the first adhesive layer and the thickness of the second adhesive layer.

In the present embodiment, the total thickness of the polarizing plate means the thickness of the polarizer, the thickness of the first adhesive layer, the thickness of the first retardation layer, the thickness of the adhesive layer, and the thickness of the second retardation layer. The thickness of the second adhesive layer and the thickness of all the optical film layers, the adhesive layer, and the adhesive layer included in the other polarizing plates are combined. As in the above, the total thickness of the polarizing plate does not include the member that is not left in the display device.

The total thickness of the polarizing plate of the present embodiment can be obtained, for example, by measuring an arbitrary value of the measured value by measuring any five points of the polarizing plate using a micrometer.

The total thickness of the polarizing plate can also be determined, for example, by the thickness of the polarizer, Thickness of the first adhesive layer, thickness of the first retardation layer, thickness of the adhesive layer, thickness of the second retardation layer, thickness of the second adhesive layer, and all optical film layers included in other polarizing plates The thickness of the adhesive layer and the adhesive layer is obtained by totaling the values.

The thickness of the polarizer, the thickness of the first adhesive layer, the thickness of the first retardation layer, the thickness of the adhesive layer, the thickness of the second retardation layer, the thickness of the second adhesive layer, and the inclusion in other polarizing plates. The thickness of all the optical film layers, the adhesive layer, and the adhesive layer can be measured by the method described in this specification.

The total thickness Tp of the polarizing plate is preferably 30 μm or more. The total thickness Tp (μm) of the polarizing plate is preferably 300 μm or less, more preferably 200 μm or less, and still more preferably 150 μm or less. The above upper limit value and lower limit value can be arbitrarily combined.

When the total thickness of the polarizing plate is equal to or less than the above upper limit value, it is possible to contribute to thinning of the polarizing plate. When the total thickness of the polarizing plate is equal to or higher than the above lower limit value, the strength of the polarizing plate is improved.

In the present embodiment, the sum of the thickness T ₁ (μm) of the first adhesive layer and the thickness T ₂ (μm) of the second adhesive layer, that is, Ta (μm) is preferably 50 μm or less, and 45 μm or less. Preferably. The Ta system is preferably 20 μm or more.

<3rd adhesive layer>

The third adhesive that is interposed between the first retardation layer and the second retardation layer of the present embodiment is not particularly limited, and a conventionally known adhesive having excellent optical transparency can be used. The adhesive constituting the third adhesive layer can be the same as the adhesive constituting the first adhesive layer described above. Further, an active energy ray-curable adhesive can also be used. The thicknesses of the first adhesive layer, the second adhesive layer, and the third adhesive layer may be the same or different.

The thickness of the third adhesive layer is preferably 3 μm or more. The thickness of the third adhesive layer is preferably 20 μm or less, more preferably 15 μm or less, and still more preferably 10 μm or less. The above upper limit value and lower limit value can be arbitrarily combined.

When the thickness of the third adhesive layer is equal to or higher than the lower limit value, the first retardation layer and the second retardation layer can be sufficiently bonded. When the thickness of the first adhesive layer is equal to or less than the above upper limit value, the first retardation layer and the second retardation layer are less likely to be displaced, and the effect of suppressing wrinkles of the polarizing plate due to deformation of the retardation layer is suppressed.

When the laminated body of the present embodiment is produced, when the first retardation layer and the second retardation layer are bonded together via the third adhesive while using a strong pressure, when the laminate is bonded to a weaker pressure, The thickness of the third adhesive layer is thinned. This is because the third adhesive layer is formed to have stretchability. However, when the first retardation layer and the second retardation layer are bonded together, when temporarily placed, the thickness of the third adhesive layer is restored. Therefore, when the first retardation layer and the second retardation layer are bonded together with a strong pressure, for example, the thickness of the third adhesive layer can be measured after standing for 5 minutes to obtain a constant value.

In one aspect of the embodiment in which the first retardation layer and the second retardation layer are laminated via the third adhesive layer, the thickness T ₁ (μm) of the first adhesive layer and the second adhesive layer are The sum of the thickness T ₂ (μm) of the agent layer and the thickness T ₃ (μm) of the third adhesive layer, that is, Ta' (μm) divided by the total thickness Tp' (μm) of the polarizing plate, that is, Ta'/Tp' is a polarizing plate of 0.40 or less.

The above Ta'/Tp' is preferably 0.10 or more, more preferably 0.20 or more, and still more preferably 0.25 or more. The above Ta'/Tp' is preferably 0.40 or less, and more preferably 0.38 or less. The above upper limit value and lower limit value can be arbitrarily combined.

When Ta'/Tp' is equal to or less than the above upper limit value, the retardation layer is less likely to be displaced, and the effect of suppressing wrinkles of the polarizing plate due to deformation of the retardation layer is suppressed.

The value of Ta'/Tp' can be controlled by adjusting the thickness of the layer constituting the polarizing plate. It is effective to reduce the thickness of the first adhesive layer, the thickness of the second adhesive layer, and the thickness of the third adhesive layer while ensuring a certain total thickness of the polarizing plate.

The total thickness Tp' (μm) of the polarizing plate means the thickness of the polarizer, the thickness of the first adhesive layer, the thickness of the first retardation layer, the thickness of the third adhesive layer, and the second retardation layer. The thickness, the thickness of the second adhesive layer, and the thickness of all the optical film layers, the adhesive layer, and the adhesive layer included in the other polarizing plates are combined.

The total thickness of the polarizing plate of the present invention can be obtained, for example, by measuring any five points of the polarizing plate using a micrometer and calculating the average value thereof.

The total thickness of the polarizing plate of the present invention can also be measured by the thickness of the polarizer, the thickness of the first adhesive layer, the thickness of the retardation layer, the thickness of the second adhesive layer, and the thickness of the other polarizer. The thickness of all the optical film layers, the adhesive layer, and the adhesive layer is obtained by summing the value layers.

Thickness of the polarizer, thickness of the first adhesive layer, thickness of the first retardation layer, thickness of the third adhesive layer, thickness of the second retardation layer, thickness of the second adhesive layer, and other polarizing plates The thickness of all the optical film layers, the adhesive layer, and the adhesive layer included can be measured using the method described in the present specification.

The total thickness Tp' (μm) of the polarizing plate is preferably 30 μm or more, and more preferably 50 μm or more. Further, the total thickness of the polarizing plate is preferably 300 μm or less, more preferably 200 μm or less, and still more preferably 150 μm or less. Further, the above upper limit value and lower limit value can be arbitrarily combined.

When the total thickness of the polarizing plate is equal to or less than the above upper limit value, it is possible to contribute to thinning of the polarizing plate. When the total thickness of the polarizing plate is equal to or higher than the above lower limit value, the strength of the polarizing plate is improved.

The thickness T ₁ (μm) of the first adhesive layer and the thickness T ₂ (μm) of the second adhesive layer and the thickness T ₃ (μm) of the third adhesive layer, that is, Ta' (μm) are It is preferably 50 μm or less, and preferably 45 μm or less. The Ta' system is preferably 20 μm or more.

<<Manufacturing method of polarizing plate>>

An example of a method of manufacturing the polarizing plate of the present invention will be described below.

[Method of Manufacturing Polarizer]

The polarizer is usually produced by the following steps: a step of uniaxially stretching a PVA-based film; a step of dyeing a PVA-based film with a dichroic dye to adsorb a dichroic dye; and using an aqueous boric acid solution; The step of treating the PVA-based film to which the dichroic dye is adsorbed and crosslinking the mixture; and the step of performing the water-washing after the crosslinking treatment using the aqueous boric acid solution (hereinafter also referred to as boric acid treatment).

The uniaxial stretching of the PVA-based film can be carried out before dyeing with a dichroic dye, simultaneously with dyeing, or after dyeing. When uniaxially extending after dyeing, the uniaxial stretching can be carried out before the boric acid treatment or in the boric acid treatment. It is of course also possible to perform a uniaxial extension at the complex phase shown here. The uniaxial extension system can adopt the following method: a method of uniaxially extending in a film conveying direction between rolls having different peripheral speeds; a uniaxial stretching method using a hot roll in a film conveying direction; and a tenter in a width direction The method of extension, etc. Further, the uniaxial stretching can be carried out by dry stretching in the air, or by stretching in a state where the PVA film is swollen by using a solvent such as water. Extension ratio It is usually about 3 to 8 times.

The dyeing of the PVA-based film using a dichroic dye can be carried out, for example, by immersing the PVA-based film in an aqueous solution containing a dichroic dye. As the dichroic dye, specifically, iodine and a dichroic organic dye can be used. Further, the PVA-based film is preferably subjected to a treatment of immersion in water and swelling before the dyeing treatment.

When iodine is used as the dichroic dye, a method in which a PVA-based film is immersed in an aqueous solution containing iodine and potassium iodide and dyed is usually used. The content of iodine in the aqueous solution is usually about 0.01 to 1 part by mass per 100 parts by mass of the water, and the content of potassium iodide is usually about 0.5 to 20 parts by mass per 100 parts by mass of water. The temperature of the aqueous solution used for dyeing is usually about 20 to 40 °C. Further, the immersion time (dyeing time) of the aqueous solution is usually about 20 to 1,800 seconds.

On the other hand, when a dichroic organic dye is used as the dichroic dye, a method in which a PVA-based film is immersed in an aqueous solution containing a water-soluble dichroic organic dye and dyed is usually used. The content of the dichroic organic dye in the aqueous solution is usually from 0.0001 to 10 parts by mass, preferably from 0.001 to 1 part by mass, per 100 parts by mass of water. The aqueous dye solution may also contain an inorganic salt such as sodium sulfate as a dyeing aid. The temperature of the aqueous solution of the dichroic organic dye used for dyeing is usually about 20 to 80 °C. Further, the immersion time (dyeing time) of the aqueous solution is usually about 10 to 1,800 seconds.

The boric acid treatment after dyeing using a dichroic dye can be carried out by immersing the dyed PVA-based film in an aqueous solution containing boric acid. The content of boric acid in the aqueous solution containing boric acid is usually from 2 to 15 parts by mass, preferably from 5 to 12 parts by mass per 100 parts by mass of water. When iodine is used as the dichroic dye, the boric acid-containing aqueous solution contains potassium iodide. It is better. The content of potassium iodide in the aqueous solution containing boric acid is usually from 0.1 to 15 parts by mass, preferably from 5 to 12 parts by mass per 100 parts by mass of the water. The immersion time in the aqueous solution containing boric acid is usually from about 60 to 1,200 seconds, preferably from 150 to 600 seconds, more preferably from 200 to 400 seconds. The temperature of the aqueous solution containing boric acid is usually 50 ° C or higher, preferably 50 to 85 ° C, more preferably 60 to 80 ° C.

The PVA-based film after the boric acid treatment is usually subjected to a water washing treatment. The water washing treatment can be carried out, for example, by immersing a boric acid-treated PVA-based film in water. The temperature of the water treated with water is usually about 5 to 40 °C. Further, the immersion time is usually about 1 to 120 seconds.

After washing, drying treatment was carried out to obtain a polarizer. The drying treatment can be carried out using a hot air dryer and a far infrared heater. The temperature of the drying treatment is usually about 30 to 100 ° C, preferably 50 to 80 ° C. The drying treatment time is usually about 60 to 600 seconds, preferably 120 to 600 seconds. By the drying treatment, the moisture content in the polarizer can be reduced to a practical level. The moisture content is usually from about 5 to 20% by mass, preferably from 8 to 15% by mass, based on the total mass of the polarizer. When the water content is 5% by mass or more, since the polarizer has sufficient flexibility, it is possible to suppress damage or breakage after drying. Further, when the water content is 20% by mass or less, the polarizer has sufficient thermal stability.

As described above, the polarizing plate 11 in which the dichroic dye is adsorbed and aligned to the PVA-based film can be produced.

The polarizer obtained above may be further bonded to one surface or both surfaces of the polarizer via the above-mentioned adhesive.

[Method for Producing First Adhesive Layer, Second Adhesive Layer, and Third Adhesive Layer]

As described above, the first adhesive layer, the second adhesive layer, and the third adhesive layer are preferably formed of an adhesive containing an acrylic resin as a matrix polymer.

The (meth)acrylic resin (1) can be usually produced by a conventional polymerization method such as a solution polymerization method, a bulk polymerization method, a suspension polymerization method, or an emulsion polymerization method. In the production of the (meth)acrylic resin (1), polymerization is usually carried out in the presence of a polymerization initiator. The amount of the polymerization initiator to be used is usually 0.001 to 5 parts by mass based on 100 parts by mass of the total of all the monomers constituting the (meth)acrylic resin (1). The (meth)acrylic resin (1) can also be produced by a method of polymerization by an active energy ray such as ultraviolet light.

As a polymerization initiator, a thermal polymerization initiator and a photopolymerization initiator are mentioned. As a photopolymerization initiator, 4-(2-hydroxyethoxy)phenyl (2-hydroxy-2-propyl) ketone is mentioned. Examples of the thermal polymerization initiator include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), and 1,1'-azobis (cyclohexane). Alkan-1-carbonitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxypentyl) Azo compound such as nitrile), dimethyl 2,2'-azobis(2-methylpropionate), 2,2'-azobis(2-hydroxymethylpropionitrile), peroxidized laurel Bismuth, tert-butyl hydroperoxide, benzammonium peroxide, tert-butyl peroxybenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, dipropyl peroxydicarbonate, An organic peroxide such as oxidized neodecanoic acid tert-butyl ester, trimethyl butyl peroxyacetate, peroxidized (3,5,5-trimethylhexyl), potassium persulfate or ammonium persulfate, An inorganic peroxide such as hydrogen peroxide. Further, a redox initiator which is obtained by using a peroxide and a reducing agent in combination can also be used as a polymerization initiator.

The (meth)acrylic resin (1) is preferably produced by a solution polymerization method. Specifically, the desired monomer is mixed with an organic solvent, and will be under a nitrogen atmosphere. A thermal polymerization initiator is added to the resulting solution. The (meth) acrylate polymer can be obtained by stirring the obtained mixture at about 40 ° C to 90 ° C, preferably at about 60 ° C to 80 ° C for about 3 to 10 hours. In order to control the polymerization reaction, a monomer, a thermal polymerization initiator, or both may be added to the reaction system continuously or intermittently in the polymerization reaction, or may be added to the reaction system in a state of being dissolved in an organic solvent. Examples of the organic solvent include an aromatic hydrocarbon solvent such as toluene or xylene, an ester solvent such as ethyl acetate or butyl acetate, an aliphatic alcohol solvent such as propanol or isopropanol, acetone or methyl ethyl ketone. A ketone solvent such as methyl isobutyl ketone.

The (meth)acrylic resin (1) obtained in this manner can be obtained by mixing the crosslinking agent (2), the decane compound (3), and the necessary organic solvent to obtain an adhesive composition. Solution. As the organic solvent, the same ones as those used in the above liquid phase polymerization can be used. The coating solution can be applied, for example, to an adherend and dried to form an adhesive layer. Further, the coating solution can be applied, for example, to a separator and dried to form an adhesive layer on the separator.

As a method of applying the coating solution of the above-described adhesive composition to an adherend or a separator, a die coater, a knife coater, a reverse roll coater, a gravure coater, or the like is used. A general coating technique such as a bar coater, a wire bar coater, a doctor blade applicator, or a pneumatic blade coater may be used.

The separator is preferably composed of a plastic film and a release layer. Examples of the plastic film include a polyester film such as a polyethylene terephthalate film, a polybutylene terephthalate film, and a polyethylene naphthalate film, and a polyolefin film such as a polypropylene film. .

Further, the release layer can be formed, for example, from a composition for forming a release layer. The main component (resin) constituting the composition for forming a release layer is not particularly limited, and examples thereof include polyfluorene oxide resin and alcohol. Acid resin, acrylic resin, and long-chain alkyl resin.

The thickness of the first adhesive layer, the second adhesive layer, and the third adhesive layer can be adjusted according to the type of the adhesive composition. In order to make the thickness of the adhesive layer thin, it is effective to reduce the coating thickness.

[Method of Manufacturing Phase Difference Layer]

As described above, the retardation layer may have a layer in which a liquid crystal compound is cured, and further has a transparent substrate and an alignment layer.

The alignment layer is formed of a layer composed of the above-mentioned resin, and a composition for an alignment layer containing a monomer forming the above-mentioned resin is applied onto a transparent substrate to be dried, and then formed by a predetermined hardening treatment. The alignment layer is formed using the cured product thus formed.

The solvent (diluting solvent) to be used in the composition for the alignment layer is not particularly limited as long as it can dissolve the alignment material in a desired concentration. For example, a hydrocarbon solvent such as benzene or hexane or a methyl group can be exemplified. a ketone solvent such as ketone (MEK), methyl isobutyl ketone (MIBK) or cyclohexanone (CHN); an ether solvent such as tetrahydrofuran, 1,2-dimethoxyethane or propylene glycol monoethyl ether; a halogenated alkyl solvent such as chloroform or dichloromethane; an ester solvent such as methyl acetate, ethyl acetate, butyl acetate or propylene glycol monomethyl ether acetate; or N,N-dimethylformamide or the like. A guanamine solvent; an anthraquinone solvent such as dimethyl hydrazine; a cyclohexane solvent such as cyclohexane; and an alcohol solvent such as methanol, ethanol or isopropyl alcohol. The solvent may be one type or a mixed solvent of two or more types of solvents.

As a method of applying the composition for an alignment layer to a transparent substrate, a die coater, a knife coater, a reverse roll coater, a gravure coater, a bar coater, and a winding method are used. A general coating technique such as a wire bar coater, a doctor blade applicator, or a pneumatic blade applicator can be used.

A layer obtained by curing a liquid crystal compound can be formed by applying a coating liquid containing a polymerizable liquid crystal compound to the alignment layer, drying it, and then performing a predetermined hardening treatment. The retardation layer is formed using the cured product thus formed.

The content of the polymerizable liquid crystal compound is not particularly limited, and may be in the range of 5 to 40% by mass based on the total mass of the coating liquid containing the polymerizable liquid crystal compound. When the viscosity or the like is to be adjusted in accordance with the coating method applied to the alignment layer, the content of the polymerizable liquid crystal compound may be adjusted. The polymerizable liquid crystal compound can be used alone or in combination of two or more.

The coating liquid containing the above polymerizable liquid crystal compound is usually dissolved in a solvent (diluting solvent) as described above, and is preferably a solvent inert to the polymerization reaction of the polymerizable liquid crystal compound.

As a method of applying a coating liquid containing a polymerizable liquid crystal compound, a conventional method such as a wire bar coating method, an extrusion coating method, a straight roll gravure coating method, a reverse roll gravure coating method, or the like is employed. And the mold coating method can be used.

The phase difference layer is obtained by polymerizing the polymerizable liquid crystal compound contained in the film formed on the alignment layer. The polymerization method may be selected in accordance with the type of the polymerizable group of the polymerizable liquid crystal compound. When the polymerizable group is a photopolymerizable group, it can be polymerized by a photopolymerization method. Further, when the polymerizable group is a thermally polymerizable group, it can be polymerized by a thermal polymerization method. In the method for producing a phase difference layer of the present embodiment, a photopolymerization method is preferred. Since the photopolymerization method does not require heating of the transparent substrate to a high temperature, a transparent substrate having low heat resistance can be used. The photopolymerization method irradiates visible light, or violet, on a film composed of a liquid crystal composition containing a polymerizable liquid crystal compound. It is carried out by external light. In terms of ease of operation, ultraviolet light is preferred.

[Manufacturing method of laminated body including two-layer retardation layer]

A method of manufacturing a laminate formed of two retardation layers included in the polarizing plate of the second embodiment will be described. The first retardation layer and the second retardation layer are laminated on each other via the adhesive layer or the third adhesive layer.

When the first retardation layer and the second retardation layer are laminated via the adhesive layer, the above-described water-based adhesive or active energy ray-curable adhesive is applied to the first retardation layer and the second retardation layer. The second retardation layer of the first retardation layer is bonded to either or both of them.

When a water-based adhesive is used, the laminate can be subsequently cured by using the above-described drying method to obtain a laminate including two retardation layers. On the other hand, when an active energy ray-curable adhesive is used, a laminate including two retardation layers can be obtained by irradiating an adhesive with an ultraviolet ray as an example of an energy ray.

The laminate including the two retardation layers can be a laminate in which a transparent substrate, an alignment layer, a first retardation layer, an adhesive layer, a second retardation layer, an alignment layer, and a transparent substrate are sequentially laminated. The transparent substrate and the alignment layer can be peeled off before the phase difference layer is bonded to the polarizing plate.

When the first retardation layer and the second retardation layer are laminated via the third adhesive layer, the first retardation layer or the second retardation layer can be bonded to, for example, a release film which is subjected to release treatment. The surface of the third adhesive layer formed on the surface of the third adhesive layer is opposite to the surface on which the separator is laminated.

The first retardation layer and the second retardation layer can be bonded to a surface on which the separator of the third adhesive layer is peeled off and exposed.

When the energy ray-curable adhesive is used as the third adhesive layer, the adhesive force can be adjusted by irradiating the energy line such as ultraviolet rays.

The laminated body including the two retardation layers is formed by sequentially laminating a transparent substrate, an alignment layer, a first retardation layer, a third adhesive layer, a second retardation layer, an alignment layer, and a transparent substrate. Laminated body. The transparent substrate and the alignment layer can be peeled off before the phase difference layer is bonded to the polarizing plate.

[Method of Manufacturing Polarizing Plate of First Embodiment]

An example of a method of manufacturing the polarizing plate 100 of the first embodiment in which the phase difference layer is one layer will be described below. Moreover, the polarizer, the adhesive layer, and the retardation layer used in the present embodiment can be manufactured by the above method.

As the adhesive, the above-described adhesive composition or an adhesive layer formed on the separator can be used. Hereinafter, a case where the adhesive layer formed on the separator is used as the first adhesive layer and the second adhesive layer will be described as an example.

The polarizer 11 and the first adhesive layer 12 are laminated. Specifically, the polarizer 11 can be bonded by bonding the surface of the first adhesive layer 12 located on the opposite side of the first adhesive layer 12 to the surface on which the separator is laminated, and one surface of the polarizer 11 . Laminated with the first adhesive layer 12.

Subsequently, the first adhesive layer 12 and the phase difference layer 14 are laminated.

The first adhesive layer 12 and the retardation layer 14 can be laminated by bonding the retardation layer 14 to the surface of the first adhesive layer 12 which is exposed by peeling off the separator. The surface of the retardation layer 14 that is in contact with the first adhesive layer 12 is a surface of the alignment layer in which the transparent substrate is peeled off and exposed. Or the surface of the retardation layer 14 on the opposite side to the alignment layer.

Subsequently, the phase difference layer 14 and the second adhesive layer 13 are laminated.

By laminating the surface of the second adhesive layer 13 opposite to the surface on which the separator is laminated, the phase difference layer 14 and the second adhesive layer 13 can be laminated. The surface of the retardation layer 14 contacting the second adhesive layer 13 is located on the surface of the retardation layer 14 on the side opposite to the surface in contact with the first adhesive layer 12.

The polarizing plate 100 of the first embodiment may be laminated on a display panel or the like with the second adhesive layer 13 interposed therebetween.

[Method for Manufacturing Polarizing Plate of Second Embodiment]

An example of a method of manufacturing the polarizing plate 101 of the second embodiment will be described below. The polarizer, the adhesive layer, and the retardation layer used in the present embodiment can be produced by the above method.

As the adhesive, the above-described adhesive composition or an adhesive layer formed on the separator can be used. Hereinafter, a case where the adhesive layer formed on the separator is used as the first adhesive layer and the second adhesive layer will be described as an example.

The polarizer 11 and the first adhesive layer 12 are laminated. Specifically, the polarizer 11 and the first adhesive layer 12 can be bonded by bonding the surface of the first adhesive layer 12 opposite to the surface on which the separator is laminated and the surface of the polarizer 11 . Laminated.

Subsequently, the first adhesive layer 12 and the laminated volume layer including the two retardation layers are laminated.

It is possible to bond the laminate including the two retardation layers to the first adhesion The surface of the layer 12 on which the separator of the agent layer 12 is peeled off is exposed, and the first adhesive layer 12 and the laminated layer are laminated. The surface of the layered body that is in contact with the first adhesive layer 12 is peeled off by any one of the transparent substrates located at both ends of the layered body including the phase difference layer, and the surface of the alignment layer is exposed or contained. The surface of the retardation layer exposed by any of the transparent base material and the alignment layer at both ends of the laminated body of the difference layer is peeled off.

Subsequently, a laminate including two retardation layers is laminated with the second adhesive layer 13.

The laminate and the second adhesive layer 13 can be laminated by bonding the surface of the second adhesive layer 13 opposite to the surface on which the separator is laminated to the laminate including the two retardation layers. The surface of the layered body that is in contact with the second adhesive layer 13 is located on the surface opposite to the surface of the first adhesive layer 12 in contact with the laminated body of the retardation layer, and the transparent substrate is peeled off to expose the alignment layer. The surface of the exposed retardation layer is peeled off from the transparent substrate and the alignment layer.

The polarizing plate 101 of the second embodiment may be laminated on a display panel or the like via the second adhesive layer 13.

When the polarizing plate having the above configuration is used, wrinkles of the polarizing plate accompanying deformation of the retardation layer can be suppressed even in a high-temperature and high-humidity environment.

<Use>

The polarizing plate of the present invention can be used in a wide variety of display devices. A display device is a device having a display element, and includes a light-emitting element or a light-emitting device as a light-emitting source. Examples of the display device include a liquid crystal display device, an organic EL display device, and inorganic electroluminescence (hereinafter Also known as inorganic EL) display devices, electronic emission display devices (such as electric field radiation display devices (also known as FED), surface electric field radiation display devices (also known as SED)), electronic paper (using electronic ink and electrophoretic moving elements) Display device), plasma display device, projection display device (for example, GLV (GLV) display device, display device with digital micromirror device (also known as DMD; digital micromirror device) ) and piezoelectric ceramic displays.

The liquid crystal display device also includes any of a transmissive liquid crystal display device, a transflective liquid crystal display device, and the like. The display device may be a display device that displays a two-dimensional image or a stereoscopic display device that displays a three-dimensional image.

The present polarizing plate can be used particularly effectively in an organic EL display device or an inorganic EL display device in particular.

[Examples]

Hereinafter, the present invention will be described in more detail by way of examples, but the invention is not limited by the examples. Various assays and evaluations were performed as follows.

[Measurement of Weight Average Molecular Weight (Mw)]

The weight average molecular weight (Mw) of the (meth)acrylic resin for forming an adhesive layer is a polystyrene-equivalent weight average molecular weight measured by gel permeation chromatography (GPC) under the following conditions.

[Measurement conditions]

. GPC measuring device: manufactured by TOSOH Co., Ltd., HLC-8020

. GPC pipe string (through the following order): manufactured by TOSOH Co., Ltd.

TSK guard column HXL-H

TSK gel GMHXL (×2)

TSK gel G2000HXL

. Determination of solvent: tetrahydrofuran

. Measuring temperature: 40 ° C

[Determination of Thickness of Polarizing Plate and Adhesive Layer]

The thickness of the polarizing plate and the adhesive layer was measured using a digital micrometer MH-15M manufactured by Nikon Co., Ltd.

[Measurement of moisture permeability ratio]

The moisture permeability ratio of the phase difference layer was measured as follows.

The adhesive composition F described later was applied onto a substrate using a bar coater to form an adhesive composition layer having a thickness of 2 to 3 μm, and a laminate for moisture permeability evaluation of the substrate was obtained. As the substrate, a cellulose triacetate film manufactured by Konica Minolta Co., Ltd. was used.

Further, the phase difference layer was laminated on the adhesive composition layer of the laminate for moisture permeability evaluation of the substrate, and a laminate for moisture permeability evaluation of the phase difference layer was obtained.

The moisture permeability of the obtained laminated body for evaluation was measured in accordance with JIS Z 0208:1976 "Test method for moisture permeability of moisture-proof packaging materials (cup method)" under the conditions of a temperature of 40 ° C and a humidity of 90% RH.

Further, the cellulose triacetate film used had a thickness of 20 μm. Further, the cellulose triacetate film having a moisture permeability of 1200 g/m ² was obtained in the same manner as above. 24h.

The moisture permeability of the laminate for moisture permeability evaluation of the aforementioned substrate was 1000 g/m ² . 24h.

The moisture permeability of the laminate for evaluating the moisture permeability of the phase difference layer was measured by dividing the moisture permeability of the laminate for moisture permeability evaluation of the substrate.

[Determination of moisture permeability (water vapor permeability)]

The water vapor permeability of the adhesive layer was measured under the conditions of a temperature of 40 ° C and a humidity of 90% RH using a water vapor permeability measuring machine (manufactured by Lyssy, model name "Lyssy-L80-5000").

[Manufacture of adhesive]

The adhesive was produced by the following method.

[Manufacture of Adhesives A to E]

In a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen introduction tube, 97.0 parts by mass of n-butyl acrylate, 1.0 part by mass of acrylic acid, 0.5 parts by mass of 2-hydroxyethyl acrylate, and 200 mass of ethyl acetate were added. And 0.08 parts by mass of 2,2'-azobisisobutyronitrile, and the air in the above reaction vessel was replaced with nitrogen. The reaction solution was heated to 60 ° C under stirring in a nitrogen atmosphere, and allowed to react for 6 hours, and then cooled to room temperature. When the weight average molecular weight of a part of the obtained solution was measured, it was confirmed that a (meth) acrylate polymer having a weight average molecular weight of 1.8 million was produced.

100 parts by mass of the (meth) acrylate polymer obtained in the above step (converted solid content; the same applies hereinafter), and trimethylolpropane modified toluene diisocyanate as an isocyanate crosslinking agent (manufactured by TOSOH Co., Ltd.) , the product name "CORONATE (registered trademark) L") 0.30 parts by mass, 3-glycidoxypropyltrimethoxydecane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBM403") 0.30 as a decane coupling agent The parts by mass were mixed and sufficiently stirred, and a coating solution of the adhesive composition was obtained by diluting with ethyl acetate.

The coating solution was dried to a thickness of 6 μm (adhesive A) and 10 μm (adhesive) using a coater on a release-treated surface (peeling layer) of a separator (manufactured by LINTEC Co., Ltd.: SP-PLR382190). B), 15 μm (adhesive C), 20 μm (adhesive D), 25 μm (adhesive E) After the coating, the film was dried at 100 ° C for 1 minute, and the other separator (manufactured by LINTEC Co., Ltd.: SP-PLR381031) was bonded to the opposite side of the surface of the adhesive layer to which the separator was bonded. Adhesive layer with a separator on both sides.

The moisture permeability (water vapor permeability) of Adhesive A, Adhesive B, Adhesive C, Adhesive D, and Adhesive E was 8200 g/m ² . 24h, 6800g/m ² . 24h, 6300g/m ² . 24h, 4700g/m ² . 24h, 3600g/m ² . 24h.

[Manufacture of Adhesive F]

In a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen introduction tube, 95.0 parts by mass of n-butyl acrylate, 4.0 parts by mass of acrylic acid, 1.0 part by mass of 2-hydroxyethyl acrylate, and 200 mass of ethyl acetate were added. And 0.08 parts by mass of 2,2'-azobisisobutyronitrile, and the air in the above reaction vessel was replaced with nitrogen. The reaction solution was heated to 60 ° C under stirring in a nitrogen atmosphere, and allowed to react for 6 hours, and then cooled to room temperature. When the weight average molecular weight of a part of the obtained solution was measured, it was confirmed that a (meth) acrylate polymer having a weight average molecular weight of 1.8 million was produced.

100 parts by mass of the (meth) acrylate polymer obtained in the above step (converted solid content; the same applies hereinafter), and trimethylolpropane modified toluene diisocyanate as an isocyanate crosslinking agent (manufactured by TOSOH Co., Ltd., Product name "CORONATE (registered trademark) L") 0.3 parts by mass of 3-glycidoxypropyltrimethoxydecane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBM403") as a decane coupling agent 7.5 parts by mass of ethoxylated isocyanuric acid triacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.: product name "A-9300") as an ultraviolet curable compound, and 2 as a photopolymerization initiator -methyl 1-(4-methylthiophenyl)-2-morpholinepropan-1-one (manufactured by BASF Corporation: IRGACURE (registered trademark) 907) 0.5 mass mixed, and diluted with ethyl acetate by thorough stirring A coating solution of the adhesive composition was obtained.

The release coating film (release layer) of the separator (SP-PLR382190) was coated with the applicator in a thickness of 5 μm (adhesive F) after drying. After the cloth was dried at 100 ° C for 1 minute, and another insulating film (SP-PLR381031, manufactured by LINTEC Co., Ltd.) was bonded to the surface of the adhesive layer opposite to the surface to which the separator was bonded. The adhesive layer was obtained by irradiating ultraviolet rays (irradiation intensity: 500 mW/cm ² , integrated light amount: 500 mJ/cm ² ) through a release sheet using an ultraviolet irradiation device (manufactured by Fusion UV Systems, Inc., using D bulb) with a conveyor belt. Adhesive layer with a separator on both sides.

The water vapor permeability of the adhesive F was 7600 g/m ² . 24h.

[Manufacture of polarizer]

A polyvinyl alcohol film having an average polymerization degree of about 2400 and a saponification degree of 99.9 mol% or more and a thickness of 30 μm was uniaxially stretched by about 5 times by dry stretching, and impregnated at 60 ° C in pure water while maintaining tension. After 1 minute, it was immersed in an aqueous solution of iodine:potassium iodide:water at a mass ratio of 0.05:5:100 at 28 ° C for 60 seconds. Subsequently, it was immersed in an aqueous solution of potassium iodide:boric acid:water at a mass ratio of 8.5:8.5:100 at 72 ° C for 300 seconds. Subsequently, it was washed with pure water at 26 ° C for 20 seconds, and then dried at 65 ° C to obtain a polarizer having an iodine adsorption alignment of 12 μm in thickness of polyvinyl alcohol. Next, on one side of the polarizer, 3 parts of carboxy-modified polyvinyl alcohol [trade name "KL-318" obtained from KURARAY] was dissolved in 100 parts of water, and 1.5 parts of water-soluble was added to the aqueous solution. Polyamide amine epoxy resin additive [trade name obtained from Tiangang Chemical Industry Co., Ltd. An epoxy-based adhesive prepared by "Sumirez Resin (registered trademark) 650 (30)", an aqueous solution having a solid concentration of 30%], and a decene-based resin film having a thickness of 30 μm was bonded as a transparent protective film. The film was bonded such that one surface was surface-treated and the other surface was bonded to the polarizer. On the other side of the polarizer, a cellulose acetate-based resin film having a thickness of 20 μm was bonded thereto using the above-mentioned adhesive. In this manner, a polarizing plate (1) having a thickness of 62 μm formed of a protective film of a two-layer layer of a polarizer was obtained.

[Manufacture of the first retardation layer]

The first retardation layer is a layer obtained by curing a nematic liquid crystal compound, an alignment film, and a layer of a phase difference of λ/4 which is composed of a transparent substrate. Further, the total thickness of the layer obtained by curing the nematic liquid crystal compound and the alignment layer was 2 μm. Further, the moisture permeability ratio of the first retardation layer was 0.48.

[Manufacture of second retardation layer]

A polyethylene terephthalate substrate having a thickness of 38 μm was used as a transparent substrate, and a composition for a vertical alignment layer was applied to one surface of the transparent substrate so as to have a thickness of 3 μm, and a polarized light of 20 mJ/cm ² was irradiated. The alignment layer is produced by ultraviolet rays. Further, as the composition for the vertical alignment layer, 2-phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, dipentaerythritol triacrylate, and bis(2-vinyloxyethyl) ether were used. A 1:1:4:5 ratio was mixed and a mixture of LUCIRIN (registered trademark) TPO as a polymerization initiator was added in a ratio of 4%.

Subsequently, a liquid crystal composition containing photopolymerizable nematic liquid crystal (RMM28B, manufactured by Merck) was applied onto the alignment layer by die coating on the formed alignment layer. Here, in the liquid crystal composition, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), and cyclohexanone (CHN) having a boiling point of 155 ° C are used in mass ratio (MEK: MIBK: CHN). ) is 35:30: A mixed solvent of a ratio of 35 is used as a solvent. In addition, the liquid crystal composition prepared so as to have a solid content of 1 to 1.5 g is applied onto the alignment layer so that the coating amount is 4 to 5 g (wet).

After the liquid crystal composition was applied onto the alignment layer, the drying temperature was set to 75 ° C, and the drying time was set to 120 seconds to carry out a drying treatment. Subsequently, the liquid crystal compound is polymerized by irradiation of ultraviolet rays (UV) to obtain a layer obtained by curing the photopolymerizable nematic liquid crystal compound, an alignment layer, and a positive C layer composed of a transparent substrate. The total thickness of the layer obtained by curing the photopolymerizable nematic liquid crystal compound and the alignment layer was 4 μm. Further, the moisture permeability ratio of the second retardation layer was 0.60.

Two sheets of the first retardation layer were bonded to each other with a retardation layer (a surface opposite to the transparent substrate) as a bonding surface by using an ultraviolet curable adhesive. Next, the ultraviolet curable adhesive was cured by irradiation with ultraviolet rays, and the thickness of the ultraviolet curable adhesive after curing was 2 μm. In this manner, the layered body (1) including the first retardation layer and the second retardation layer is produced.

The first retardation layer and the second retardation layer are bonded to each other with the phase difference layer (the surface opposite to the transparent substrate) as the bonding surface by using the adhesive F. In this manner, the layered body (2) including the first retardation layer and the second retardation layer is produced.

[Example 1]

The adhesive A having a thickness of 6 μm was transferred to the cellulose triacetate film surface of the polarizing plate (1) as a first adhesive layer. The separator deposited on the adhesive A is peeled off and laminated on the surface on which the transparent substrate on the first retardation layer side of the laminate (1) is peeled off. The transparent substrate is peeled off on the side opposite to the surface on which the polarizing plate (1) is laminated on the laminated body (1). The adhesive E of a thickness of 25 μm was laminated on the surface on which the transparent substrate was peeled off and exposed as a second adhesive layer. This is done by a protective film, Polarizer, protective film, first adhesive layer, first retardation layer (layer for supplying λ/4 phase difference), adhesive layer, second retardation layer (positive C layer), and second adhesive layer The polarizing plate is constructed. The total thickness Tp of the obtained polarizing plate was 101 μm, and the thickness Ta of the adhesive layer was 31 μm.

[Examples 2 to 6]

A polarizing plate was produced in the same manner as in Example 1 except that the materials described in Table 1 were used as the first adhesive and the second adhesive. The total thickness Tp of the obtained polarizing plate and the thickness Ta of the adhesive layer are shown in Table 1.

[Examples 7 to 8]

A polarizing plate was produced in the same manner as in Example 1 except that the material described in Table 1 was used as the first adhesive and the second adhesive, and the laminated body (2) was used as the retardation layer.

The thickness of the third adhesive layer was 5 μm. The total thickness Tp of the obtained polarizing plate and the thickness Ta of the adhesive layer are shown in Table 1.

[Comparative Example 1]

A polarizing plate was produced in the same manner as in Example 1 except that the material described in Table 1 was used as the first adhesive and the second adhesive, and the laminated body (2) was used as the retardation layer.

The thickness of the third adhesive layer was 5 μm. That is, the total thickness Tp' of the polarizing plate was 118 μm, and the thickness Ta' of the adhesive layer was 50 μm.

[Comparative Example 2]

A polarizing plate was produced in the same manner as in Example 1 except that the adhesive described in Table 1 was used as the first adhesive and the second adhesive. The total thickness Tp of the obtained polarizing plate and the thickness Ta of the adhesive layer are shown in Table 1.

<Evaluation of polarizing plate in high temperature and high humidity environment>

The separator of the second adhesive layer of the polarizing plate produced as described above was peeled off and bonded to an alkali-free glass plate [Eagle-XG" manufactured by Corning Co., Ltd.] as an evaluation sample. The above evaluation sample was subjected to pressure treatment in an autoclave at a temperature of 50 ° C and a pressure of 5 MPa for 20 minutes, and then left for 1 day in an environment of a temperature of 23 ° C and a relative humidity of 60%. Subsequently, it was placed in an environment of 65 ° C and a humidity of 90%. After the evaluation sample was placed in an environment of 65 ° C and a humidity of 90%, the appearance of the sample was visually confirmed after 168 hours and 336 hours.

In Table 1, the sample which does not cause wrinkles on the polarizing plate is described as "A" even when 336 hours have elapsed, and the sample in which the polarizing plate can confirm wrinkles is described as "B" at 336 hours. The sample in which the wrinkles can be confirmed in the hour-level polarizing plate is described as "C".

In Table 1, Ta/Tp indicates that the thickness T ₁ (μm) of the first adhesive layer and the thickness T ₂ (μm) of the second adhesive layer when the polarizing plate does not include the third adhesive layer are Ta (μm) A value obtained by dividing the total thickness Tp (μm) of the polarizing plate.

Ta'/Tp' indicates the thickness T ₁ (μm) of the first adhesive layer and the thickness T ₂ (μm) of the second adhesive layer and the thickness of the third adhesive layer when the polarizing plate includes the third adhesive layer. The sum of T ₃ (μm), that is, the value obtained by dividing Ta' (μm) by the total thickness Tp' (μm) of the polarizing plate.

As shown in Table 1, the polarizing plates of Examples 1 to 8 were polarized even after exposure for 168 hours in a high-temperature, high-humidity environment of Ta/Tp (Ta'/Tp') of 0.40 or less and 65 ° C and a humidity of 90%. No wrinkles were confirmed on the board.

As shown in Table 1, in Comparative Example 1 and Comparative Example 2, Ta/Tp (Ta'/Tp') was more than 0.40, and wrinkles were observed on the polarizing plate at 168 hours.

From the above results, the present invention can be shown to be useful.

[Industrial availability]

Since the polarizing plate of the present invention does not cause wrinkles even in a high-temperature, high-humidity environment, it can be applied to an image display device which is likely to be used in an environment of high temperature and high humidity.

Claims (3)

A polarizing plate comprising, in order, a polarizer, a first adhesive layer, a retardation layer, and a polarizer of a second adhesive layer; wherein a thickness T ₁ (μm) of the first adhesive layer is different from the first 2 The sum of the thickness T ₂ (μm) of the adhesive layer, that is, the value obtained by dividing Ta (μm) by the total thickness Tp (μm) of the polarizing plate, that is, Ta/Tp is 0.40 or less, and the thickness of the polarizer is It is 15 μm or less. The polarizing plate according to claim 1, further comprising an adhesive layer, and the first retardation layer, the adhesive layer, and the second retardation layer are sequentially included. A polarizing plate comprising, in order, a polarizer, a first adhesive layer, a retardation layer, and a polarizer of a second adhesive layer; wherein a thickness T ₁ (μm) of the first adhesive layer is different from the first 2 the sum of the thickness T ₂ (μm) of the adhesive layer and the thickness T ₃ (μm) of the third adhesive layer, that is, Ta' (μm) divided by the total thickness Tp' (μm) of the polarizing plate The value of Ta'/Tp' is 0.40 or less, and the thickness of the polarizer is 15 μm or less.