KR20210107016A - Polarizing plate with retardation layer - Google Patents

Abstract

The present invention provides a polarizing plate with a retardation layer which is excellent in durability in spite of being very thin. A polarizing plate with a retardation layer of the present invention includes a polarizing plate including a polarizer and a protective layer disposed on one side of the polarizer, and a retardation layer disposed on the opposite side to the protective layer of the polarizing plate. The protective layer is composed of a solidified product of a coating film of an organic solvent solution of a thermoplastic acrylic resin, and the protective layer has a glass transition temperature of 95°C or higher. In one embodiment, the thickness of the protective layer is 10 μm or less.

Description

Polarizing plate with retardation layer

The present invention relates to a polarizing plate with a retardation layer.

In image display devices (eg, liquid crystal display devices, organic EL display devices), a polarizing plate is disposed on at least one side of a display cell in many cases due to the image forming method thereof. Moreover, practically, a retardation plate is used together with a polarizing plate in many cases, and the polarizing plate with a retardation layer which integrated a polarizing plate and a retardation plate is used widely (for example, patent document 1). In recent years, thickness reduction and flexibility of an image display apparatus are progressing, and thickness reduction of the polarizing plate with a retardation layer is also strongly requested|required by this. However, the more thin the polarizing plate with a retardation layer, the more remarkable the problem of durability that the optical characteristic in a heating and humidification environment falls.

Japanese Patent Publication No. 3325560

The present invention has been made in order to solve the above conventional problems, and its main object is to provide a polarizing plate with a retardation layer which is excellent in durability in spite of being very thin.

A polarizing plate with a retardation layer of the present invention includes a polarizing plate including a polarizer and a protective layer disposed on one side of the polarizer, and a retardation layer disposed on the opposite side of the protective layer of the polarizing plate. The protective layer is composed of a solidified product of a coating film of an organic solvent solution of a thermoplastic acrylic resin, and the protective layer has a glass transition temperature of 95°C or higher.

In one embodiment, the retardation layer is a single layer, Re (550) of the retardation layer is 100 nm to 190 nm, and the angle between the slow axis of the retardation layer and the absorption axis of the polarizer is 40° to 50 is °. In this case, a resin film may be sufficient as the said retardation layer, and the alignment solidification layer of a liquid crystal compound may be sufficient as it.

In another embodiment, the retardation layer has a laminated structure of a first layer and a second layer, Re (550) of the first layer is 200 nm to 300 nm, and the slow axis thereof and the absorption axis of the polarizer are The angle formed is 10° to 20°, Re (550) of the second layer is 100 nm to 190 nm, and the angle formed between its slow axis and the absorption axis of the polarizer is 70° to 80°. In this case, a resin film may be sufficient as said 1st layer and a 2nd layer, respectively, and the alignment solidification layer of a liquid crystal compound may be sufficient as it.

In one embodiment, the thickness of the protective layer is 10 μm or less.

In one embodiment, the iodine adsorption amount of the protective layer is 4.0% by weight or less.

In one embodiment, the thermoplastic acrylic resin has at least one selected from the group consisting of a lactone ring unit, a glutaric anhydride unit, a glutarimide unit, a maleic anhydride unit, and a maleimide unit.

In one embodiment, the said polarizing plate with a retardation layer is arrange|positioned at the visual recognition side of an image display apparatus, and the said protective layer is arrange|positioned at the visual recognition side.

According to the present invention, in a polarizing plate with a retardation layer, the protective layer is composed of a solidified product of a coating film of an organic solvent solution of a thermoplastic acrylic resin, and the glass transition temperature thereof is set to a predetermined value or more. A polarizing plate can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic sectional drawing of the polarizing plate with retardation layer which concerns on one Embodiment of this invention.
2 is a schematic cross-sectional view of a polarizing plate with a retardation layer according to another embodiment of the present invention.
Fig. 3 is a schematic diagram showing an example of drying shrinkage treatment using a heating roll in a method for manufacturing a polarizing plate that can be used for a polarizing plate with a retardation layer according to an embodiment of the present invention.

(Definition of terms and symbols)

Definitions of terms and symbols in the present specification are as follows.

(1) refractive index (nx, ny, nz)

'nx' is the refractive index in the direction in which the in-plane refractive index is maximized (ie, the slow axis direction), 'ny' is the refractive index in the direction orthogonal to the slow axis in the plane (ie, the fast axis direction), and 'nz' is It is the refractive index in the thickness direction.

(2) In-plane phase difference (Re)

'Re(λ)' is the in-plane retardation measured with light having a wavelength of λ nm at 23°C. For example, 'Re(550)' is the in-plane retardation measured with light having a wavelength of 550 nm at 23°C. Re(λ) can be obtained by the formula: Re(λ)=(nx-ny)×d when the thickness of the layer (film) is d(nm).

(3) Thickness direction retardation (Rth)

'Rth(λ)' is the retardation in the thickness direction measured with light having a wavelength of λnm at 23°C. For example, 'Rth (550)' is the retardation in the thickness direction measured with light having a wavelength of 550 nm at 23°C. Rth(λ) can be obtained by the formula: Rth(λ)=(nx-nz)×d when the thickness of the layer (film) is d(nm).

(4) Nz coefficient

Nz coefficient can be calculated|required by Nz=Rth/Re.

(5) angle

When referring to an angle herein, the angle includes both clockwise and counterclockwise directions with respect to the reference direction. Thus, for example, '45°' means ±45°.

A. Outline of polarizing plate with retardation layer

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic sectional drawing of the polarizing plate with retardation layer which concerns on one Embodiment of this invention. A polarizing plate 100 with a retardation layer of the illustrated example includes a polarizer 10, a protective layer 20 disposed on one side of the polarizer 10, and a retardation layer 40 disposed on the other side of the polarizer 10. include The polarizer 10 and the protective layer 20 constitute a polarizing plate. Accordingly, the polarizing plate with a retardation layer includes a polarizing plate including a polarizer and a protective layer disposed on one side of the polarizer, and a retardation layer disposed on the opposite side of the protective layer of the polarizing plate. If necessary, the polarizing plate may further include another protective layer (not shown) on the side opposite to the protective layer 20 of the polarizer 10 . In other words, the polarizing plate 100 with a retardation layer may further include another protective layer (not shown) between the polarizer 10 and the retardation layer 40 . In a polarizing plate with a retardation layer, the thickness of the polarizer 10 becomes like this. Preferably it is 8 micrometers or less.

In the embodiment shown in FIG. 1 , the retardation layer 40 is a single layer. In this case, Re (550) of the retardation layer 40 is, for example, 100 nm to 190 nm, and the angle between the slow axis of the retardation layer 40 and the absorption axis of the polarizer 10 is, for example, 40° to 50°. am. In this case, another retardation layer (not shown) is preferably provided outside the retardation layer 40 (on the side opposite to the polarizer 10 ). The other retardation layers typically exhibit the relationship of refractive index characteristics of nz>nx=ny. Alternatively, as shown in FIG. 2 , in the polarizing plate 101 with a retardation layer according to another embodiment, the retardation layer 40 has a laminated structure of the first layer 41 and the second layer 42 . In this case, Re (550) of the first layer 41 is, for example, 200 nm to 300 nm, and the angle between the slow axis of the first layer 41 and the absorption axis of the polarizer 10 is, for example, 10° to 20 °, the Re(550) of the second layer 42 is, for example, 100 nm to 190 nm, and the angle between the slow axis of the second layer 42 and the absorption axis of the polarizer 10 is, for example, 70° to 80°. am. In any embodiment, a resin film may be sufficient as the retardation layer 40, and the alignment solidification layer of a liquid crystal compound may be sufficient as it. When the retardation layer 40 has a laminated structure, typically, the first layer 41 and the second layer 42 are each a resin film or an alignment-solidified layer of a liquid crystal compound.

In embodiment of this invention, the protective layer 20 is comprised from the solidified material of the coating film of the organic solvent solution of a thermoplastic acrylic resin. With such a configuration, the protective layer can be made very thin (eg, 10 µm or less). In addition, the protective layer can be formed directly on the polarizer (that is, without intervening an adhesive layer or an adhesive layer). According to embodiment of this invention, since a polarizer and a protective layer are very thin as mentioned above, and an adhesive bond layer or an adhesive layer can be omitted, the total thickness of a polarizing plate with a retardation layer can be made extremely thin. When the retardation layer is composed of a resin film, the total thickness of the polarizing plate with a retardation layer is, for example, 80 µm or less, preferably 70 µm or less, and more preferably 60 µm or less. The lower limit of the total thickness of the polarizing plate with a retardation layer may be, for example, 30 µm. When the retardation layer is composed of an alignment-solidified layer of a liquid crystal compound, the total thickness of the polarizing plate with a retardation layer is, for example, 25 µm or less, preferably 22 µm or less, and more preferably 20 µm or less. The lower limit of the total thickness of the polarizing plate with a retardation layer may be, for example, 10 µm.

Moreover, in embodiment of this invention, the glass transition temperature (Tg) of the protective layer 20 is 95 degreeC or more, Preferably it is 100 degreeC or more, More preferably, it is 105 degreeC or more, More preferably, it is 110 degreeC. or more, and particularly preferably 115°C or more. If the Tg of the protective layer is in such a range, a polarizing plate excellent in durability despite being very thin (results polarizing plate with retardation layer) can be realized. Specifically, a polarizing plate (as a result, a polarizing plate with a retardation layer) in which a decrease in optical properties is suppressed even in a heating and humidification environment can be realized. On the other hand, Tg of the protective layer is preferably 300°C or lower, more preferably 250°C or lower, still more preferably 200°C or lower, and particularly preferably 160°C or lower. When the Tg of the protective layer is within such a range, the formability may be excellent.

As mentioned above, according to embodiment of this invention, the polarizing plate by which the fall of the optical characteristic was suppressed also in a heating and humidification environment (as a result, a polarizing plate with a retardation layer) can be implement|achieved. In such a polarizing plate (as a result, a polarizing plate with a retardation layer), the amount of change (ΔTs) in the single transmittance (Ts) and the amount of change (ΔP) in the degree of polarization (P) after leaving it to stand for 48 hours under an environment of 85°C and 85%RH Very small. The single transmittance (Ts) can be measured using, for example, an ultraviolet/visible light spectrophotometer (manufactured by Japan Spectroscopy, product name 'V7100'). The degree of polarization (P) is calculated by the following equation from the single transmittance (Ts), the parallel transmittance (Tp), and the orthogonal transmittance (Tc) measured using an ultraviolet/visible light spectrophotometer.

Polarization degree (P)(%) = {(Tp-Tc)/(Tp+Tc)} ^1/2 × 100

In addition, said Ts, Tp, and Tc are the Y values which measured with the 2 degree field of view (C light source) of JIS Z 8701, and performed visibility correction|amendment. In addition, Ts and P are substantially characteristics of a polarizer. ΔTs and ΔP can be obtained by the following equations, respectively.

ΔTs(%)=Ts ₄₈ -Ts ₀

ΔP(%)=P ₄₈ -P ₀

Here, Ts ₀ is the single transmittance before leaving (initial), Ts ₄₈ is the single transmittance after standing, P ₀ is the polarization degree before leaving (initial), and P ₄₈ is the polarization degree after leaving it to stand. ΔTs is preferably 3.0% or less, more preferably 2.7% or less, and still more preferably 2.4% or less. ΔP is preferably -0.05% to 0%, more preferably -0.03% to 0%, still more preferably -0.01% to 0%.

The polarizing plate with a retardation layer of this invention may further contain the retardation layer other than the above. The optical characteristics (eg, refractive index characteristics, in-plane retardation, Nz coefficient, photoelastic coefficient), thickness, arrangement position, and the like of such a retardation layer can be appropriately set according to the purpose.

The polarizing plate with a retardation layer of this invention may further contain the isotropic base material with a conductive layer or a conductive layer (neither is shown). A conductive layer or an isotropic substrate with a conductive layer is typically provided on the outside of the retardation layer 40 (on the opposite side to the polarizer 10 ). When a conductive layer or an isotropic substrate with a conductive layer is provided, a polarizing plate with a retardation layer is applied to a so-called inner touch panel type input display device in which a touch sensor is embedded between a display cell (eg, a liquid crystal cell, an organic EL cell) and a polarizing plate. can

The shape of a long picture may be sufficient as a polarizing plate with retardation layer, and the shape of a sheet may be sufficient as it. When a polarizing plate with a retardation layer is elongate, Preferably it is wound in roll shape, and becomes a polarizing plate roll with a retardation layer.

Typically, the polarizing plate with a retardation layer contains an adhesive layer as an outermost layer of one side (typically the retardation layer 40 side), and bonding to a display cell is enabled. If necessary, a surface protection film and/or a carrier film may be temporarily attached to the polarizing plate with a retardation layer so that peeling is possible to reinforce and/or support the polarizing plate with a retardation layer. When the polarizing plate with a retardation layer contains an adhesive layer, a separator is releasably attached to the surface of an adhesive layer so that the adhesive layer is protected during actual use, and roll-ization of the polarizing plate with a retardation layer is made possible.

Since the polarizing plate with a retardation layer of this invention is very thin as mentioned above, it can apply suitably to a flexible image display apparatus. More preferably, the image display device has a curved shape (substantially curved display screen) and/or is bendable or bendable. Specific examples of the image display device include a liquid crystal display device and an electroluminescence (EL) display device (eg, an organic EL display device and an inorganic EL display device). Of course, the above description does not prevent the application of the polarizing plate with a retardation layer of the present invention to an ordinary image display device.

Hereinafter, the components of a polarizing plate with a retardation layer are demonstrated in detail.

B. Polarizer

B-1. polarizer

Any suitable polarizer may be employed as the polarizer. The polarizer may be typically manufactured using a laminate of two or more layers. The manufacturing method of a polarizer is mentioned later in D term as a manufacturing method of a polarizing plate.

The thickness of the polarizer is preferably 1 µm to 8 µm, more preferably 1 µm to 7 µm, and still more preferably 2 µm to 5 µm.

The boric acid content of the polarizer is preferably 10% by weight or more, and more preferably 13% by weight to 25% by weight. Appearance at the time of heating, maintaining the ease of curling adjustment at the time of bonding favorably by the synergistic effect with the iodine content mentioned later that the boric acid content of a polarizer is such a range, and suppressing the curl at the time of a heating favorably Durability can be improved. Boric acid content is computable as the amount of boric acid contained in a polarizer per unit weight using the following formula from a neutralization method, for example.

The iodine content of the polarizer is preferably 2% by weight or more, more preferably 2% by weight to 10% by weight. When the iodine content of the polarizer is within such a range, the easiness of curling adjustment at the time of bonding is maintained favorably by the synergistic effect with the boric acid content, and the appearance durability at the time of heating is improved while suppressing the curling at the time of heating favorably. can be improved In this specification, 'iodine content' means the amount of all iodine contained in the polarizer (PVA-based resin film). More specifically, iodine in the polarizing plate ^{exists in the form of iodine ions (I -} ), iodine molecules (I ₂ ), polyiodine ions (I ₃ ^- _, I ₅ ^- ), and the like, and the iodine content in the present specification is in these forms. means the amount of iodine including all The iodine content can be calculated by, for example, a calibration ray method of fluorescence X-ray analysis. In addition, polyiodine ions exist in a state in which a PVA-iodine complex is formed in the polarizer. By forming such a complex, absorption dichroism can be expressed in the wavelength range of visible light. Specifically, the complex of PVA and triiodide ion (PVA·I ₃ ⁻ ) has an absorption peak around 470 nm _{, and the complex of PVA and pentaiodide ion (PVA·I 5} ⁻ ) has an absorption peak around 600 nm. It has an absorption peak. As a result, polyiodine ions, depending on their form, can absorb light in a wide range of visible light. On the other hand, iodine ion (I ⁻ ) has an absorption peak around 230 nm and does not substantially participate in absorption of visible light. Therefore, polyiodine ions present in a complex state with PVA may be mainly involved in the absorption performance of the polarizer.

The polarizer preferably exhibits absorption dichroism at any one of wavelengths from 380 nm to 780 nm. The single transmittance (Ts) of the polarizer is preferably 40% to 48%, more preferably 41% to 46%. The polarization degree (P) of the polarizer is preferably 97.0% or more, more preferably 99.0% or more, and still more preferably 99.9% or more.

B-2. protective layer

The protective layer is composed of a solidified product of a coating film of an organic solvent solution of a thermoplastic acrylic resin (hereinafter simply referred to as an acrylic resin) as described above. Hereinafter, the constituent components of the protective layer will be specifically described, and then, the properties of the protective layer will be described.

B-2-1. Acrylic resin

The Tg of the acrylic resin (including a blend of two or more acrylic resins and a blend of an acrylic resin and another resin as described later) is the same as described in section A above with respect to the protective layer.

Any suitable acrylic resin may be employed as the acrylic resin as long as it has the above Tg. The acrylic resin typically contains an alkyl (meth)acrylate as a main component as a monomer unit (repeating unit). As used herein, '(meth)acryl' means acryl and/or methacryl. Examples of the alkyl (meth)acrylate constituting the main skeleton of the acrylic resin include a linear or branched alkyl group having 1 to 18 carbon atoms. These may be used alone or in combination. In addition, you may introduce|transduce arbitrary appropriate copolymerization monomers into acrylic resin by copolymerization. The repeating unit derived from alkyl (meth)acrylate is typically represented by the following general formula (1):

In the general formula (1), R ⁴ represents a hydrogen atom or a methyl group, and R ⁵ represents a hydrogen atom or an optionally substituted aliphatic or alicyclic hydrocarbon group having 1 to 6 carbon atoms. As a substituent, halogen and a hydroxyl group are mentioned, for example. Specific examples of the alkyl (meth)acrylate include methyl (meth)acrylate, ethyl (meth)acrylate, (meth)acrylic acid n-propyl, (meth)acrylic acid n-butyl, (meth)acrylic acid t-butyl, (meth)acrylic acid n -Hexyl, (meth)acrylic acid cyclohexyl, (meth)acrylic acid 2-ethylhexyl, (meth)acrylic acid benzyl, (meth)acrylic acid dicyclopentanyloxyethyl, (meth)acrylic acid dicyclopentanyl, (meth)acrylic acid chloromethyl, (meth)acrylic acid 2-chloroethyl, (meth)acrylic acid 2-hydroxyethyl, (meth)acrylic acid 3-hydroxypropyl, (meth)acrylic acid 2, 3, 4, 5, 6-pentahydroxyhexyl, (meth) ) acrylic acid 2, 3, 4, 5-tetrahydroxypentyl, 2-(hydroxymethyl) methyl acrylate, 2-(hydroxymethyl) ethyl acrylate, and 2-(hydroxyethyl) methyl acrylate. In the general formula (1), R ⁵ is preferably a hydrogen atom or a methyl group. Accordingly, particularly preferred alkyl (meth)acrylates are methyl acrylate or methyl methacrylate.

Acrylic resin may contain only a single alkyl (meth)acrylate unit, and may contain the some alkyl (meth)acrylate unit from which R<^4> and R<^5> in the said General formula (1) differ.

The content of the alkyl (meth)acrylate unit in the acrylic resin is preferably 50 mol% to 98 mol%, more preferably 55 mol% to 98 mol%, still more preferably 60 mol% to 98 mol%, Especially preferably, it is 65 mol% - 98 mol%, Most preferably, it is 70 mol% - 97 mol%. When the content ratio is less than 50 mol%, there is a possibility that the effect (eg, high heat resistance, high transparency) derived from the alkyl (meth)acrylate unit may not be sufficiently exhibited. When the content ratio is more than 98 mol%, the resin becomes brittle and brittle, high mechanical strength cannot be sufficiently exhibited, and there is a fear that productivity may be lowered.

The acrylic resin preferably has a repeating unit containing a ring structure. Examples of the repeating unit having a ring structure include a lactone ring unit, a glutaric anhydride unit, a glutarimide unit, a maleic anhydride unit, and a maleimide (N-substituted maleimide) unit. As for the repeating unit containing a ring structure, only one type may be contained in the repeating unit of an acrylic resin, and two or more types may be contained.

The lactone ring unit is preferably represented by the following general formula (2):

In the general formula (2), R ¹ , R ² and R ³ each independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms. Moreover, the organic residue may contain the oxygen atom. The acrylic resin may contain only a single lactone ring unit, and may contain the some lactone ring unit from which R<^1> , R<^2> and R<^3> in the said General formula (2) differs. The acrylic resin having a lactone ring unit is described in, for example, Japanese Patent Application Laid-Open No. 2008-181078, the disclosure of which is incorporated herein by reference.

The glutarimide unit is preferably represented by the following general formula (3):

In the general formula (3), R ¹¹ and R ¹² each independently represent hydrogen or an alkyl group having 1 to 8 ^{carbon atoms, and R 13} is an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, or a cycloalkyl group having 6 to 10 carbon atoms. represents an aryl group of Preferably, in the general formula (3), R ¹¹ and R ¹² are each independently hydrogen or a methyl group, and R ¹³ is hydrogen, a methyl group, a butyl group or a cyclohexyl group. More preferably, R ¹¹ is a methyl group, R ¹² is hydrogen, and R ¹³ is a methyl group. The acrylic resin may be contained in the R ^11, R ¹² and R ¹³ is different from the plurality of the glutarimide unit in and may be contained in only a single glutarimide units, the formula (3). The acrylic resin having a glutarimide unit is, for example, in Japanese Patent Application Laid-Open No. 2006-309033, Japanese Patent Application Laid-Open No. 2006-317560, Japanese Unexamined Patent Application Publication No. 2006-328334, and Japanese Patent Application Laid-Open No. 2006-337491 , Japanese Patent Application Laid-Open No. 2006-337492, Japanese Patent Application Laid-Open No. 2006-337493, and Japanese Patent Application Laid-Open No. 2006-337569, the disclosures of which are incorporated herein by reference. In addition, with respect to the glutaric anhydride unit, the above description regarding the glutarimide unit applies except that the nitrogen atom substituted by ^{R 13 in the said general formula (3) becomes an oxygen atom.}

About the maleic anhydride unit and the maleimide (N-substituted maleimide) unit, since structures are specified from a name, a specific description is abbreviate|omitted.

The content ratio of the repeating unit containing a ring structure in the acrylic resin is preferably 1 mol% to 50 mol%, more preferably 10 mol% to 40 mol%, still more preferably 20 mol% to 30 mol%. . When there is too little content rate, Tg may become less than 110 degreeC, and the heat resistance, solvent resistance, and surface hardness of the protective layer obtained may become inadequate. When there are too many content rates, a moldability and transparency may become inadequate.

Acrylic resin may contain repeating units other than the repeating unit containing an alkyl (meth)acrylate unit and a ring structure. As such a repeating unit, the repeating unit (other vinylic monomeric unit) derived from the vinylic monomer copolymerizable with the monomer which comprises the said unit is mentioned. Examples of other vinyl monomers include acrylic acid, methacrylic acid, crotonic acid, 2-(hydroxymethyl) acrylic acid, 2-(hydroxyethyl) acrylic acid, acrylonitrile, methacrylonitrile, ethacrylonitrile, allyl glycol Cydyl ether, maleic anhydride, itaconic anhydride, N-methylmaleimide, N-ethylmaleimide, N-cyclohexylmaleimide, aminoethyl acrylate, propylaminoethyl acrylate, dimethylaminoethyl methacrylate, methacrylic acid Ethylaminopropyl, methacrylic acid cyclohexylaminoethyl, N-vinyldiethylamine, N-acetylvinylamine, allylamine, metaallylamine, N-methylallylamine, 2-isopropenyl-oxazoline, 2-vinyl -Oxazoline, 2-acryloyl-oxazoline, N-phenylmaleimide, phenylaminoethyl methacrylate, styrene, α-methylstyrene, p-glycidylstyrene, p-aminostyrene, 2-styryl- Oxazoline etc. are mentioned. These may be used independently and may be used together. The kind, number, combination, content ratio, etc. of the other vinylic monomer units may be appropriately set according to the purpose.

The weight average molecular weight of the acrylic resin is preferably 1000 to 2000000, more preferably 5000 to 1000000, still more preferably 10000 to 500000, particularly preferably 50000 to 500000, and most preferably 60000 to 150000. A weight average molecular weight can be calculated|required by polystyrene conversion using, for example, gel permeation chromatography (GPC system, Tosoh Corporation). In addition, tetrahydrofuran can be used as a solvent.

The acrylic resin may be polymerized by any suitable polymerization method, using an appropriate combination of the above monomer units. You may blend 2 or more types of acrylic resin which has another monomeric unit.

In embodiment of this invention, you may use together acrylic resin and other resin. That is, a monomer component constituting the acrylic resin may be copolymerized with a monomer component constituting another resin, and the copolymer may be subjected to molding of a protective layer described later; A blend of an acrylic resin and another resin may be used for forming the protective layer. Examples of other resins include thermoplastics such as styrene resins, polyethylene, polypropylene, polyamide, polyphenylene sulfide, polyether ether ketone, polyester, polysulfone, polyphenylene oxide, polyacetal, polyimide, polyetherimide, and the like. and resin. The kind and compounding amount of the resin to be used together can be appropriately set according to the purpose and properties desired for the film obtained. For example, a styrenic resin (preferably an acrylonitrile-styrene copolymer) may be used in combination as a phase difference controlling agent.

When an acrylic resin and another resin are used together, the content of the acrylic resin in the blend of the acrylic resin and the other resin is preferably 50% by weight to 100% by weight, more preferably 60% by weight to 100% by weight, still more preferably preferably 70% to 100% by weight, particularly preferably 80% to 100% by weight. When the content is less than 50% by weight, there is a fear that the high heat resistance and high transparency inherent in the acrylic resin cannot be sufficiently reflected.

B-2-2. Composition and properties of the protective layer

The protective layer is composed of a solidified product of a coating film of an organic solvent solution of an acrylic resin as described above. If it is a solidified material of such a coating film, compared with an extrusion film, thickness can be made thin remarkably. The thickness of the protective layer is 10 µm or less, preferably 7 µm or less, more preferably 5 µm or less, and still more preferably 3 µm or less as described above. The lower limit of the thickness of the protective layer may be, for example, 1 μm. In addition, although it is not clear in theory, the solidified product of such a coating film has a smaller shrinkage during film molding than a cured product of a thermosetting resin or an active energy ray-curable resin (e.g., UV-curable resin), and does not contain residual monomers, etc. Therefore, deterioration of the film itself is suppressed, and there is an advantage that the adverse effect on the polarizing plate (polarizer) resulting from the residual monomer or the like can be suppressed. In addition, since hygroscopicity and moisture permeability are smaller than those of a solidified product of an aqueous coating film such as an aqueous solution or an aqueous dispersion, it has an advantage of excellent humidification durability. As a result, a polarizing plate excellent in durability (as a result polarizing plate with a retardation layer) which can maintain optical properties even in a heating and humidification environment can be implement|achieved.

Tg of the protective layer is the same as described in section A above.

The iodine adsorption amount of the protective layer is preferably 4.0 wt% or less, more preferably 3.0 wt% or less, still more preferably 2.0 wt% or less, particularly preferably 1.0 wt% or less, and most preferably 0.5% by weight or less. The smaller the amount of iodine adsorbed, the more preferable, and the lower limit thereof may be, for example, 0.1% by weight. If the amount of iodine adsorption is within such a range, a polarizing plate having further excellent durability (as a result, a polarizing plate with a retardation layer) can be obtained. The amount of iodine adsorption can be measured by the method described in Examples to be described later.

The protective layer is preferably substantially optically isotropic. In the present specification, 'substantially optically isotropic' means that the in-plane retardation Re(550) is 0 nm to 10 nm, and the retardation Rth(550) in the thickness direction is -20 nm to +10 nm. The in-plane retardation Re(550) is more preferably 0 nm to 5 nm, still more preferably 0 nm to 3 nm, and particularly preferably 0 nm to 2 nm. The retardation Rth (550) in the thickness direction is more preferably -5 nm to +5 nm, still more preferably -3 nm to +3 nm, and particularly preferably -2 nm to +2 nm. When Re(550) and Rth(550) of the protective layer are within such ranges, when a polarizing plate with a retardation layer including the protective layer is applied to an image display device, an adverse effect on display characteristics can be prevented.

The higher the light transmittance in 380 nm in the thickness of 3 micrometers of a protective layer, the more preferable. Specifically, the light transmittance is preferably 85% or more, more preferably 88% or more, still more preferably 90% or more. If the light transmittance is within such a range, desired transparency can be ensured. The light transmittance can be measured, for example, by a method according to ASTM-D-1003.

The lower the haze of the protective layer, the more preferable. Specifically, the haze is preferably 5% or less, more preferably 3% or less, still more preferably 1.5% or less, particularly preferably 1% or less. When the haze is 5% or less, a good clear feeling can be given to the film. Moreover, even when it is a case where a polarizing plate with a retardation layer is used for the visual recognition side of an image display apparatus, display content can be visually recognized favorably.

YI in the thickness of 3 micrometers of a protective layer becomes like this. Preferably it is 1.27 or less, More preferably, it is 1.25 or less, More preferably, it is 1.23 or less, Especially preferably, it is 1.20 or less. When YI exceeds 1.3, optical transparency may become inadequate. In addition, YI can be calculated|required by the following formula from the tristimulus values (X, Y, Z) of the color obtained by measurement using, for example, a high-speed integrating sphere type spectral transmittance|permeability measuring instrument (trade name: DOT-3C: Murakami Color Technology Research Institute make).

YI = [(1.28X-1.06Z)/Y]×100

The b-value (a color scale according to the Hunter color system) at a thickness of 3 µm of the protective layer is preferably less than 1.5, more preferably 1.0 or less. When the b value is 1.5 or more, an undesired color may appear. In addition, the b value is, for example, a sample of the film constituting the protective layer is cut to 3 cm square, and the color is measured using a high-speed integrating sphere type spectral transmittance meter (trade name: DOT-3C: Murakami Color Technology Research Institute), and the color can be obtained by evaluating according to the Hunter colorimetric system.

The protective layer (solidified material of a coating film) may contain arbitrary appropriate additives according to the objective. Specific examples of the additive include a UV absorber; leveling agent; antioxidants such as hindered phenol-based, phosphorus-based, and sulfur-based antioxidants; Stabilizers, such as a light stabilizer, a weathering stabilizer, and a heat stabilizer; Reinforcing materials, such as glass fiber and carbon fiber; near infrared absorbers; flame retardants such as tris (dibromopropyl) phosphate, triallyl phosphate, and antimony oxide; antistatic agents such as anionic, cationic and nonionic surfactants; colorants such as inorganic pigments, organic pigments, and dyes; organic or inorganic fillers; resin modifiers; organic or inorganic fillers; plasticizer; lubricant; antistatic agent; A flame retardant etc. are mentioned. An additive may be added at the time of superposition|polymerization of an acrylic resin, and may be added to a solution at the time of film formation. The type, number, combination, addition amount, etc. of the additives may be appropriately set according to the purpose.

An easily adhesive layer may be formed in the polarizer side of a protective layer. The easily adhesive layer contains, for example, a water-based polyurethane and an oxazoline-based crosslinking agent. By providing such an easily adhesive layer, the adhesiveness of a protective layer and a polarizer can be improved. Moreover, the hard-coat layer may be formed in the protective layer. The hard coat layer may be formed when the protective layer is used as a protective layer on the viewer side of the viewer-side polarizing plate. When both the easily adhesive layer and the hard coat layer are formed, typically they may each be formed on the other side of the protective layer.

B-3. Method of manufacturing a polarizing plate

B-3-1. Method for manufacturing a polarizer

In the method for manufacturing the polarizer according to item B-1, a polyvinyl alcohol-based resin layer (PVA-based resin layer) containing a halide and a polyvinyl alcohol-based resin (PVA-based resin) is formed on one side of a long thermoplastic resin substrate. to make a laminate, and to perform a drying shrinkage treatment in this order for the laminate to be shrunk by 2% or more in the width direction by heating while conveying in the longitudinal direction, including aerial auxiliary stretching treatment, dyeing treatment, underwater stretching treatment, and conveying in the longitudinal direction. include The content of the halide in the PVA-based resin layer is preferably 5 to 20 parts by weight with respect to 100 parts by weight of the PVA-based resin. The drying shrinkage treatment is preferably performed using a heating roll, and the temperature of the heating roll is preferably 60°C to 120°C. According to such a manufacturing method, the above polarizers can be obtained. In particular, by producing a laminate including a PVA-based resin layer containing a halide, stretching the laminate in multi-step stretching including air-assisted stretching and underwater stretching, and heating the laminate after stretching with a heating roll, excellent optics While having characteristics (typically, single transmittance and polarization degree), the polarizer in which the dispersion|variation of an optical characteristic was suppressed can be obtained. Specifically, by using a heating roll in the drying shrinkage treatment step, the entire laminate can be shrunk uniformly while conveying the laminate. As a result, not only can the optical properties of the obtained polarizer be improved, but a polarizer having excellent optical properties can be stably produced, and variations in the optical properties (especially single transmittance) of the polarizer can be suppressed. Hereinafter, the halide and drying shrinkage treatment will be described. About the detail of manufacturing methods other than these, it describes in Unexamined-Japanese-Patent No. 2012-73580, for example. This publication is incorporated herein by reference in its entirety.

B-3-1-1. halide

The PVA-based resin layer containing a halide and a PVA-based resin may be formed by applying a coating liquid containing a halide and a PVA-based resin on a thermoplastic resin substrate and drying the coating film. The coating solution is typically a solution in which the halide and the PVA-based resin are dissolved in a solvent. Examples of the solvent include water, dimethylsulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, various glycols, polyhydric alcohols such as trimethylolpropane, and amines such as ethylenediamine and diethylenetriamine. can These can be used individually or in combination of 2 or more types. Among these, water is preferable. The concentration of the PVA-based resin in the solution is preferably 3 parts by weight to 20 parts by weight with respect to 100 parts by weight of the solvent. If it is such a resin density|concentration, the uniform coating film closely_contact|adhered to a thermoplastic resin base material can be formed.

Any suitable halide may be employed as the halide. Examples include iodide and sodium chloride. Examples of the iodide include potassium iodide, sodium iodide and lithium iodide. Among these, potassium iodide is preferable.

The amount of the halide in the coating liquid is preferably 5 parts by weight to 20 parts by weight, more preferably 10 parts by weight to 15 parts by weight based on 100 parts by weight of the PVA-based resin. When there is too much quantity of a halide, a halide may bleed out and the polarizer finally obtained may become cloudy.

Generally, when the PVA-based resin layer is stretched, the orientation of the polyvinyl alcohol molecules in the PVA-based resin is increased, but when the PVA-based resin layer after stretching is immersed in a liquid containing water, the orientation of the polyvinyl alcohol molecules is disturbed, This may decrease. In particular, when the laminate of the thermoplastic resin substrate and the PVA-based resin layer is stretched in boric acid water, when the laminate is stretched in boric acid water at a relatively high temperature to stabilize the stretching of the thermoplastic resin substrate, the orientation degree tends to decrease. remarkable For example, in general, stretching of a PVA film alone in boric acid water is performed at 60° C., whereas stretching of a laminate of A-PET (thermoplastic resin substrate) and a PVA-based resin layer is performed at a high temperature of around 70° C. In this case, the orientation of the PVA at the initial stage of stretching may decrease at a stage before rising by underwater stretching. On the other hand, by producing a laminate of a PVA-based resin layer containing a halide and a thermoplastic resin substrate, and stretching the laminate at a high temperature in air (auxiliary stretching) before stretching the laminate in boric acid water, the PVA system of the laminate after auxiliary stretching Crystallization of the PVA-based resin in the resin layer can be promoted. As a result, when the PVA-based resin layer is immersed in a liquid, as compared to the case where the PVA-based resin layer does not contain a halide, disorder in the orientation of polyvinyl alcohol molecules and a decrease in orientation can be suppressed. Thereby, the optical properties of the polarizer obtained through the treatment process performed by immersing a laminated body in a liquid, such as a dyeing process and an underwater stretching process, can be improved.

B-3-1-2. dry shrinkage treatment

The drying shrinkage treatment may be performed by zone heating performed by heating the entire zone, or may be performed by heating a conveyance roll (using a so-called heating roll) (heating roll drying method). Preferably, both are used. By drying using a heating roll, heating curl of a laminated body can be suppressed efficiently, and the polarizer excellent in an external appearance can be manufactured. Specifically, by drying in a state in which the laminate is poured on a heating roll, crystallization of the thermoplastic resin substrate can be efficiently promoted to increase the crystallinity, and even at a relatively low drying temperature, the crystallinity of the thermoplastic resin substrate can be increased favorably. have. As a result, the rigidity of a thermoplastic resin base material increases, it becomes a state which can withstand the shrinkage of the PVA-type resin layer by drying, and curl is suppressed. Moreover, since a laminated body can be dried, maintaining a flat state by using a heating roll, not only curl but generation|occurrence|production of wrinkles can also be suppressed. At this time, the optical properties can be improved by shrinking the laminate in the width direction by drying shrinkage treatment. It is because the orientation of PVA and a PVA/iodine complex can be improved effectively. The shrinkage rate in the width direction of the laminate by the drying shrinkage treatment is preferably 2% to 10%, more preferably 2% to 8%, and particularly preferably 4% to 6%. By using a heating roll, it can shrink|contract in the width direction continuously, conveying a laminated body, and high productivity can be implement|achieved.

3 is a schematic diagram showing an example of a drying shrinkage treatment. In the drying shrinkage treatment, the laminate 200 is dried while being conveyed by the conveying rolls R1 to R6 and the guide rolls G1 to G4 heated to a predetermined temperature. In the illustrated example, the conveying rolls R1 to R6 are disposed so as to alternately and continuously heat the surface of the PVA resin layer and the surface of the thermoplastic resin substrate. For example, one surface of the laminate 200 (eg, the surface of the thermoplastic resin substrate) You may arrange|position conveyance rolls R1-R6 so that a bay may be continuously heated.

Drying conditions are controllable by adjusting the heating temperature (temperature of a heating roll) of a conveyance roll, the number of heating rolls, contact time with a heating roll, etc. The temperature of the heating roll is preferably 60°C to 120°C, more preferably 65°C to 100°C, and particularly preferably 70°C to 80°C. While the degree of crystallinity of a thermoplastic resin can be increased favorably and curl can be suppressed favorably, the optical laminated body extremely excellent in durability can be manufactured. In addition, the temperature of a heating roll can be measured with a contact thermometer. Although six conveyance rolls are provided in the example of illustration, if there are several conveyance rolls, there will be no restriction|limiting in particular. The number of conveyance rolls is 2-40 normally, Preferably 4-30 pieces are provided. The contact time (total contact time) between the laminate and the heating roll is preferably 1 second to 300 seconds, more preferably 1 to 20 seconds, and still more preferably 1 to 10 seconds.

A heating roll may be provided in a heating furnace (for example, oven), and may be provided in a normal production line (under normal temperature environment). Preferably, it is provided in the heating furnace provided with the blowing means. By using together drying by a heating roll and hot air drying, the rapid temperature change between heating rolls can be suppressed, and the contraction|shrinkage of the width direction can be controlled easily. The hot air drying temperature is preferably 30°C to 100°C. Further, the hot air drying time is preferably 1 second to 300 seconds. The wind speed of the hot air is preferably about 10 m/s to 30 m/s. In addition, the said wind speed is a wind speed in a heating furnace, and can be measured with a mini vane type digital anemometer.

Preferably, a washing treatment is performed after the underwater stretching treatment and before the drying shrinkage treatment. The washing treatment is typically performed by immersing the PVA-based resin layer in an aqueous potassium iodide solution.

In this way, a laminate of the thermoplastic resin substrate/polarizer can be obtained.

B-3-2. Method of manufacturing a polarizing plate

A coating film is formed by applying an organic solvent solution of an acrylic resin to the surface of the laminate obtained in the above B-3-1, and a protective layer is formed by solidifying the coating film.

About the acrylic resin, it is as having demonstrated in said B-2-1.

As the organic solvent, any suitable organic solvent capable of dissolving or uniformly dispersing the acrylic resin can be used. Specific examples of the organic solvent include ethyl acetate, toluene, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), cyclopentanone, and cyclohexanone.

The concentration of the acrylic resin in the solution is preferably 3 parts by weight to 20 parts by weight with respect to 100 parts by weight of the solvent. If it is such a resin density|concentration, the uniform coating film closely_contact|adhered to a polarizer can be formed.

A solution may be apply|coated to arbitrary suitable base materials, and may apply|coat to a polarizer. When apply|coating a solution to a base material, the solidified material of the coating film formed on the base material is transcribe|transferred to a polarizer. When apply|coating a solution to a polarizer, a protective layer is directly formed on a polarizer by drying (solidifying) a coating film. Preferably, the solution is applied to the polarizer and a protective layer is formed directly on the polarizer. If it is such a structure, since the adhesive bond layer or adhesive layer required for transcription|transfer can be abbreviate|omitted, the polarizing plate with a retardation layer can be made further thinner. Any suitable method can be employ|adopted as a coating method of a solution. Specific examples include a roll coat method, a spin coat method, a wire bar coat method, a dip coat method, a die coat method, a curtain coat method, a spray coat method, and a knife coat method (such as a comma coat method).

By drying (solidifying) the coating film of the solution, a protective layer can be formed. The drying temperature is preferably 100°C or less, and more preferably 50°C to 70°C. If the drying temperature is within such a range, the adverse effect on the polarizer can be prevented. The drying time may vary depending on the drying temperature. The drying time may be, for example, 1 minute to 10 minutes.

A protective layer is formed as mentioned above, and the laminated body of a thermoplastic resin base material / polarizer / protective layer can be obtained as a result. By peeling a thermoplastic resin base material from this laminated body, the polarizing plate containing the polarizer 10 and the protective layer 20 as shown in FIGS. 1 and 2 can be obtained. By forming the retardation layer 40 on the polarizer surface of such a polarizing plate, a polarizing plate with a retardation layer can be obtained. Alternatively, the resin film constituting the retardation layer may be bonded to the surface of the polarizer of the laminate of the thermoplastic resin substrate/polarizer, and then the thermoplastic resin substrate may be peeled off to form a protective layer on the peeling surface. In this case, a polarizing plate with a retardation layer can be obtained with high manufacturing efficiency. In addition, since the method well-known in the industry is employ|adopted for formation of the retardation layer, detailed description is abbreviate|omitted and it will be briefly described in Section C to be described later.

C. Retardation layer

C-1. Retardation layer composed of a single layer

When the retardation layer is composed of a single layer, the retardation layer has Re (550) of, for example, 100 nm to 190 nm, as described above, and the slow axis of the retardation layer 40 and the absorption axis of the polarizer 10 form The angle is, for example, 40° to 50°. The retardation layer is typically provided to impart antireflection properties to the polarizing plate, and may function as a λ/4 plate in one embodiment. A resin film may be sufficient as the retardation layer as mentioned above, and the alignment solidification layer of a liquid crystal compound may be sufficient as it.

The retardation layer preferably exhibits a relation of refractive index characteristics of nx>ny≥nz. As described above, the in-plane retardation Re(550) of the retardation layer is, for example, 100 nm to 190 nm, preferably 110 nm to 170 nm, and more preferably 130 nm to 160 nm. In addition, 'ny=nz' here includes not only the case where ny and nz are completely the same but also the case where they are substantially the same. Therefore, there may be a case where ny<nz is not impaired in the effect of the present invention.

The Nz coefficient of the retardation layer is preferably 0.9 to 3, more preferably 0.9 to 2.5, still more preferably 0.9 to 1.5, and particularly preferably 0.9 to 1.3. By satisfying such a relationship, when the obtained polarizing plate with retardation layer is used for an image display apparatus, the very excellent reflection hue can be achieved.

The angle θ between the slow axis of the retardation layer 40 and the absorption axis of the polarizer 10 is, for example, 40° to 50°, preferably 42° to 48°, more preferably about 45° as described above. am. When the angle θ is in such a range, a polarizing plate with a retardation layer having very excellent circular polarization characteristics (as a result very excellent antireflection characteristics) can be obtained by making the retardation layer a λ/4 plate.

The retardation layer may exhibit an inverse dispersion wavelength characteristic in which the phase difference value increases with the wavelength of the measurement light, or a positive wavelength dispersion characteristic in which the phase difference value decreases with the wavelength of the measurement light, and the phase difference value is the wavelength of the measurement light It may exhibit a flat wavelength dispersion characteristic that hardly changes even depending on . In one embodiment, the retardation layer exhibits inverse dispersion wavelength characteristics. In this case, Re(450)/Re(550) of the retardation layer is preferably 0.8 or more and less than 1, and more preferably 0.8 or more and 0.95 or less. With such a configuration, very excellent antireflection properties can be realized.

Retardation layer is preferably the absolute value of photoelastic coefficient of ² × 10- ¹¹ m 2 / N or less, more preferably ^{2.0 × 10- 13 m 2 /N~1.5×10- 11} m 2 / N, more preferably is 1.0 × a resin of ^{10- 12 m 2 /N~1.2×10- 11 m 2} / N. When the absolute value of the photoelastic coefficient is within such a range, a phase difference change hardly occurs when a shrinkage stress during heating occurs. As a result, thermal unevenness of the resulting image display apparatus can be prevented favorably.

C-1-1. resin film

When the retardation layer is a resin film, the resin film is typically a stretched film. In this case, the thickness of the retardation layer is preferably 60 µm or less, and more preferably 30 µm to 55 µm. Curl|Karl at the time of bonding can be adjusted favorably, suppressing the curl at the time of a heating as the thickness of retardation layer is such a range favorably.

The retardation layer may be composed of any suitable resin film capable of satisfying the above characteristics. Representative examples of such resins include polycarbonate resins, polyester carbonate resins, polyester resins, polyvinyl acetal resins, polyarylate resins, cyclic olefin resins, cellulose resins, polyvinyl alcohol resins, Polyamide-type resin, polyimide-type resin, polyether-type resin, polystyrene-type resin, and acrylic resin are mentioned. These resins may be used independently and may be used in combination (for example, blend, copolymerization). When the retardation layer is composed of a resin film exhibiting reverse dispersion wavelength characteristics, a polycarbonate-based resin or a polyester carbonate-based resin (hereinafter, simply referred to as a polycarbonate-based resin) may be suitably used.

Any suitable polycarbonate-type resin can be used as said polycarbonate-type resin, so long as the effect of this invention is acquired. For example, the polycarbonate-based resin includes a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and an alicyclic diol, alicyclic dimethanol, di, tri or polyethylene and a structural unit derived from at least one dihydroxy compound selected from the group consisting of glycol and alkylene glycol or spiroglycol. Preferably, the polycarbonate-based resin includes a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from alicyclic dimethanol and/or di , containing a structural unit derived from tri or polyethylene glycol; More preferably, it includes a structural unit derived from a fluorene-based dihydroxy compound, a structural unit derived from an isosorbide-based dihydroxy compound, and a structural unit derived from di, tri, or polyethylene glycol. Polycarbonate-type resin may contain the structural unit derived from another dihydroxy compound as needed. Further, details of polycarbonate-based resins that can be suitably used in the present invention are, for example, Japanese Patent Application Laid-Open Nos. 2014-10291, 2014-26266, and 2015-212816, It is described in Unexamined-Japanese-Patent No. 2015-212817 and Unexamined-Japanese-Patent No. 2015-212818, The said description is incorporated herein by reference.

It is preferable that the glass transition temperature of the said polycarbonate-type resin is 110 degreeC or more and 150 degrees C or less, More preferably, they are 120 degrees C or more and 140 degrees C or less. When the glass transition temperature is excessively low, heat resistance tends to deteriorate, there is a possibility of causing a dimensional change after film forming, and the image quality of the organic EL panel obtained may be lowered. When the glass transition temperature is excessively high, the molding stability at the time of film molding may deteriorate, and the transparency of the film may be impaired. In addition, a glass transition temperature can be calculated|required according to JISK7121 (1987).

The molecular weight of the polycarbonate-based resin may be expressed as reduced viscosity. The reduced viscosity is measured by using methylene chloride as a solvent to precisely prepare the polycarbonate concentration to 0.6 g/dL, and at a temperature of 20.0° C.±0.1° C. using an Uberode viscosity tube. As for the lower limit of reduced viscosity, 0.30 dL/g is preferable normally, More preferably, it is 0.35 dL/g or more. As for the upper limit of reduced viscosity, 1.20 dL/g is preferable normally, More preferably, it is 1.00 dL/g, More preferably, it is 0.80 dL/g. When the reduced viscosity is smaller than the lower limit, a problem may arise that the mechanical strength of the molded article becomes small. On the other hand, when a reduced viscosity is larger than the said upper limit, the fluidity|liquidity at the time of shaping|molding may fall, and the problem that productivity and a moldability fall may arise.

You may use a commercially available film as a polycarbonate-type resin film. Specific examples of the commercially available products include “Pure Ace WR-S”, “Pure Ace WR-W”, “Pure Ace WR-M” manufactured by Teijin Corporation, and “NRF” manufactured by Nitto Denko.

The retardation layer 40 is obtained, for example, by stretching a film formed from the polycarbonate-based resin. As a method of forming a film from a polycarbonate-based resin, any suitable molding processing method may be employed. Specific examples include a compression molding method, a transfer molding method, an injection molding method, an extrusion molding method, a blow molding method, a powder molding method, an FRP molding method, a cast coating method (eg, a casting method), a calender molding method, a hot pressing method, and the like. An extrusion molding method or a cast coating method is preferable. It is because the smoothness of the film obtained can be improved and favorable optical uniformity can be acquired. Molding conditions may be appropriately set according to the composition or type of the resin used, characteristics desired for the retardation layer, and the like. Moreover, as mentioned above, since many film products are marketed as for polycarbonate-type resin, you may use the said commercially available film for a extending|stretching process as it is.

The thickness of the resin film (unstretched film) may be set to any appropriate value depending on the desired thickness of the retardation layer, desired optical properties, stretching conditions described later, and the like. Preferably it is 50 micrometers - 300 micrometers.

For the stretching, any suitable stretching method and stretching conditions (eg, stretching temperature, stretching ratio, stretching direction) may be employed. Specifically, various stretching methods such as free-end stretching, fixed-end stretching, free-end contraction, fixed-end contraction, etc. may be used alone, simultaneously or sequentially. The stretching direction can also be carried out in various directions and dimensions, such as the longitudinal direction, the width direction, the thickness direction, and the oblique direction. It is preferable that the temperature of extending|stretching is Tg-30 degreeC - Tg+60 degreeC with respect to the glass transition temperature (Tg) of a resin film, More preferably, they are Tg-10 degreeC - Tg+50 degreeC.

By appropriately selecting the stretching method and stretching conditions, a retardation film having the desired optical properties (eg, refractive index characteristic, in-plane retardation, Nz coefficient) can be obtained.

In one embodiment, the retardation film is produced by uniaxial stretching or fixed-end uniaxial stretching of a resin film. As a specific example of fixed-end uniaxial stretching, the method of extending|stretching in the width direction (transverse direction) is mentioned, driving a resin film in a longitudinal direction. The draw ratio is preferably 1.1 to 3.5 times.

In another embodiment, the retardation film can be produced by continuously obliquely stretching a long resin film in the direction of the angle θ with respect to the longitudinal direction. By adopting oblique stretching, an elongated stretched film having an orientation angle of angle θ (slow axis in the direction of angle θ) with respect to the longitudinal direction of the film is obtained, for example, roll-to-roll operation is possible during lamination with a polarizer. , the manufacturing process can be simplified. Also, the angle θ may be an angle between the absorption axis of the polarizer and the slow axis of the retardation layer in the polarizing plate with a retardation layer. As described above, the angle θ is preferably 40° to 50°, more preferably 42° to 48°, and still more preferably about 45°.

The stretching machine used for diagonal stretching includes, for example, a tenter type stretching machine capable of applying a feeding force, a tensile force, or a pulling force at different speeds in the transverse and/or longitudinal directions. The tenter type stretching machine includes a transverse uniaxial stretching machine, a simultaneous biaxial stretching machine, and the like, but any suitable stretching machine may be used as long as it can continuously diagonally stretch a long resin film.

By appropriately controlling the left and right speeds in the stretching machine, a retardation layer (substantially a long retardation film) having the desired in-plane retardation and a slow axis in the desired direction can be obtained.

The stretching temperature of the film may vary depending on the in-plane retardation value and thickness desired for the retardation layer, the type of resin used, the thickness of the film used, the draw ratio, and the like. Specifically, the stretching temperature is preferably Tg-30°C to Tg+30°C, more preferably Tg-15°C to Tg+15°C, and most preferably Tg-10°C to Tg+10°C. By stretching at such a temperature, it is possible to obtain a retardation layer having suitable characteristics in the present invention. In addition, Tg is the glass transition temperature of the constituent material of a film.

C-1-2. Alignment solidified layer of liquid crystal compound

When the retardation layer is an alignment-solidified layer of a liquid crystal compound, by using the liquid crystal compound, the difference between nx and ny of the obtained retardation layer can be significantly increased compared to that of a non-liquid crystal material, so the thickness of the retardation layer for obtaining a desired in-plane retardation can be significantly reduced. As a result, further thinning of the polarizing plate with a retardation layer can be implement|achieved. In the present specification, the term 'alignment-solidified layer' refers to a layer in which the liquid crystal compound is oriented in a predetermined direction in the layer and the alignment state is fixed. In addition, the 'alignment-solidified layer' is a concept including an alignment-hardened layer obtained by curing a liquid crystal monomer as will be described later. In this embodiment, the rod-shaped liquid crystal compounds are typically oriented in a state in which they are aligned in the slow axis direction of the retardation layer (homogeneous alignment).

As a liquid crystal compound, the liquid crystal compound (nematic liquid crystal) whose liquid crystal phase is a nematic phase is mentioned, for example. As such a liquid crystal compound, for example, a liquid crystal polymer or a liquid crystal monomer can be used. The liquid crystalline expression mechanism of the liquid crystal compound may be lyotropic, thermotropic, or any. A liquid crystal polymer and a liquid crystal monomer may be used independently, respectively, and may be combined.

When the liquid crystal compound is a liquid crystal monomer, the liquid crystal monomer is preferably a polymerizable monomer and a crosslinkable monomer. This is because the alignment state of the liquid crystal monomer can be fixed by polymerizing or crosslinking (ie, curing) the liquid crystal monomer. After aligning the liquid crystal monomers, for example, if the liquid crystal monomers are polymerized or crosslinked, the alignment state can be fixed accordingly. Here, a polymer is formed by polymerization, and a three-dimensional network structure is formed by crosslinking, which are non-liquid crystalline. Therefore, in the formed retardation layer, for example, transition to a liquid crystal phase, a glass phase, and a crystal phase according to a temperature change peculiar to a liquid crystal compound does not occur. As a result, the retardation layer becomes a retardation layer which is not affected by a temperature change and is extremely excellent in stability.

The temperature range in which the liquid crystal monomer exhibits liquid crystallinity differs depending on the type. Specifically, the temperature range is preferably 40°C to 120°C, more preferably 50°C to 100°C, and most preferably 60°C to 90°C.

Any suitable liquid crystal monomer may be employed as the liquid crystal monomer. For example, the polymerizable mesogenic compounds described in Japanese Patent Application Publication Nos. 2002-533742 (WO00/37585), EP358208 (US5211877), EP66137 (US4388453), WO93/22397, EP0261712, DE19504224, DE4408171 and GB2280445, etc. can be used. Specific examples of such a polymerizable mesogenic compound include BASF's brand name LC242, Merck's brand name E7, and Wacker-Chem's brand name LC-Sillicon-CC3767, for example. As the liquid crystal monomer, for example, a nematic liquid crystal monomer is preferable.

The alignment-solidified layer of the liquid crystal compound is subjected to an alignment treatment on the surface of a predetermined substrate, and a coating solution containing a liquid crystal compound is applied to the surface to align the liquid crystal compound in a direction corresponding to the alignment treatment, and the alignment state It can be formed by fixing In one embodiment, the substrate is any suitable resin film, and the alignment-solidifying layer formed on the substrate can be transferred to the surface of the polarizer 10 . In other embodiments, the substrate may be another protective layer. In this case, the transfer process is omitted, and since lamination can be performed by roll-to-roll successively from the formation of the orientation-solidified layer (retardation layer), productivity is further improved.

Any suitable alignment treatment may be employed as the alignment treatment. Specifically, a mechanical orientation process, a physical orientation process, and a chemical orientation process are mentioned. As a specific example of a mechanical orientation treatment, a rubbing process and an extending|stretching process are mentioned. Specific examples of the physical alignment treatment include magnetic field alignment treatment and electric field alignment treatment. As a specific example of a chemical orientation process, an oblique vapor deposition method and a photo-alignment process are mentioned. As for the processing conditions of various orientation treatments, any suitable conditions may be employ|adopted according to the objective.

The alignment of the liquid crystal compound is performed by treatment at a temperature that exhibits a liquid crystal phase depending on the type of the liquid crystal compound. By performing such a temperature treatment, a liquid crystal compound takes a liquid crystal state, and the said liquid crystal compound orientates according to the orientation treatment direction of the surface of a base material.

In one embodiment, fixing of an orientation state is performed by cooling the liquid crystal compound orientated as mentioned above. When the liquid crystal compound is a polymerizable monomer or a crosslinkable monomer, the alignment state is fixed by subjecting the liquid crystal compound aligned as described above to a polymerization treatment or a crosslinking treatment.

The specific example of a liquid crystal compound and the detail of the formation method of an alignment solidification layer are described in Unexamined-Japanese-Patent No. 2006-163343. The disclosure of this publication is incorporated herein by reference.

As another example of the alignment-solidified layer, a form in which the discotic liquid crystal compound is oriented in any one of a vertical alignment, a hybrid alignment, and an oblique alignment is exemplified. Typically, the discotic liquid crystal compound has a disk plane of the discotic liquid crystal compound oriented substantially perpendicular to the film plane of the retardation layer. When the discotic liquid crystal compound is substantially perpendicular, the average value of the angle between the film plane and the disk plane of the discotic liquid crystal compound is preferably 70° to 90°, more preferably 80° to 90°, still more preferably is 85° to 90°. The discotic liquid crystal compound generally refers to a cyclic parent nucleus such as benzene, 1,3,5-triazine, carixarene, etc. as the center of the molecule, and a straight-chain alkyl group, alkoxy group, substituted benzoyloxy group or the like is a side chain thereof. It refers to a liquid crystal compound having a radially substituted disk-shaped molecular structure. Representative examples of discotic liquid crystals include benzene derivatives, triphenylene derivatives, truxene derivatives, and phthalocyanine derivatives described in a research report by C. Destrade et al., Mol.Cryst.Liq.Cryst. vol. 71, p. 111 (1981). B. Kohne et al., a cyclohexane derivative described in Angew. Chem. vol. 96, p. 70 (1984), and a research report by J M Lehn et al., J. Chem. Soc. Chem. Commun., 1794. Page (1985), a research report by J. Zhang et al., and J. Am. Chem. Soc. 116, pp. 2655 (1994), azacrown and phenylacetylene macrocycles. As another specific example of a discotic liquid crystal compound, the compound of Unexamined-Japanese-Patent No. 2006-133652, Unexamined-Japanese-Patent No. 2007-108732, and Unexamined-Japanese-Patent No. 2010-244038 is mentioned, for example. The descriptions of these documents and publications are incorporated herein by reference.

When the retardation layer is an alignment-solidified layer of a liquid crystal compound, the thickness thereof is preferably 0.5 µm to 7 µm, more preferably 1 µm to 5 µm. By using a liquid crystal compound, the in-plane retardation equivalent to a resin film can be implement|achieved with thickness remarkably thinner than a resin film.

C-1-3. other retardation layer

When the retardation layer 40 is composed of a single layer as described above, another retardation layer is preferably provided. The other retardation layer may be a so-called positive C plate, in which refractive index characteristics exhibit a relationship of nz>nx=ny as described above. By using the positive C plate as the other retardation layer, reflection in the oblique direction can be prevented favorably, and wide viewing angles of the antireflection function can be made possible. In this case, the retardation Rth (550) in the thickness direction of the other retardation layer is preferably -50 nm to -300 nm, more preferably -70 nm to -250 nm, further preferably -90 nm to -200 nm, Especially preferably, it is -100 nm - -180 nm. Here, 'nx=ny' includes not only the case where nx and ny are strictly the same, but also the case where nx and ny are substantially the same. That is, the in-plane retardation Re (550) of the other retardation layer may be less than 10 nm.

Another retardation layer having a refractive index characteristic of nz>nx=ny may be formed of any suitable material. The other retardation layer is preferably formed of a film comprising a liquid crystal material fixed in homeotropic orientation. The liquid crystal material (liquid crystal compound) capable of homeotropic alignment may be a liquid crystal monomer or a liquid crystal polymer. Specific examples of the liquid crystal compound and the method for forming the retardation layer include the liquid crystal compound and the method for forming the retardation layer described in [0020] to [0028] of Japanese Patent Application Laid-Open No. 2002-333642. In this case, the thickness of the other retardation layer is preferably 0.5 µm to 10 µm, more preferably 0.5 µm to 8 µm, and still more preferably 0.5 µm to 5 µm.

C-2. Retardation layer of two-layer structure

When the retardation layer 40 has a laminated structure of the first layer 41 and the second layer 42, either one of the first layer 41 and the second layer 42 functions as a λ/4 plate. and the other side can function as a λ/2 plate. For example, when the first layer 41 functions as a λ/2 plate and the second layer 42 functions as a λ/4 plate, the in-plane retardation Re (550) of the first layer is, for example, 200 as described above. They are nm - 300 nm, Preferably they are 230 nm - 290 nm, More preferably, they are 250 nm - 280 nm. As described above, the in-plane retardation Re(550) of the second layer is, for example, 100 nm to 190 nm, preferably 110 nm to 170 nm, and more preferably 130 nm to 160 nm. The angle between the slow axis of the first layer and the absorption axis of the polarizer is, for example, 10° to 20°, preferably 12° to 18°, and more preferably about 15° as described above. The angle between the slow axis of the second layer and the absorption axis of the polarizer is, for example, 70° to 80°, preferably 72° to 78°, and more preferably about 75° as described above. With such a configuration, a characteristic close to the ideal reverse wavelength dispersion characteristic can be obtained, and as a result, a very excellent antireflection characteristic can be realized.

One of the first layer 41 and the second layer 42 may be a resin film and the other may be an alignment-solidified layer of a liquid crystal compound, both may be a resin film, or both may be an alignment-solidified layer of a liquid crystal compound. Preferably, the first layer 41 and the second layer 42 are both a resin film or an alignment-solidified layer of a liquid crystal compound.

The thicknesses of the first layer 41 and the second layer 42 can be adjusted so as to obtain a desired in-plane retardation of the λ/4 plate or the λ/2 plate. For example, the first layer 41 functions as a λ/2 plate, the second layer 42 functions as a λ/4 plate, and the first layer 41 and the second layer 42 are resin films In the case of , the thickness of the first layer 41 is, for example, 40 μm to 75 μm, and the thickness of the second layer 42 is, for example, 30 μm to 55 μm. When the first layer 41 and the second layer 42 are alignment-solidified layers of a liquid crystal compound, the thickness of the first layer 41 is, for example, 2.0 μm to 3.0 μm, and the thickness of the second layer 42 is For example, it is 1.0 micrometer - 2.0 micrometers.

The resin film constituting the first layer and the second layer, the liquid crystal compound, the method of forming the first layer and the second layer, optical properties, and the like are as described above for the single layer.

D. Conductive layer or isotropic substrate with conductive layer

The conductive layer may be formed by depositing a metal oxide film on any suitable substrate by any suitable film formation method (eg, vacuum deposition method, sputtering method, CVD method, ion plating method, spray method, etc.). Examples of the metal oxide include indium oxide, tin oxide, zinc oxide, indium-tin composite oxide, tin-antimony composite oxide, zinc-aluminum composite oxide, and indium-zinc composite oxide. Among them, indium-tin composite oxide (ITO) is preferable.

When a conductive layer contains a metal oxide, the thickness of this conductive layer becomes like this. Preferably it is 50 nm or less, More preferably, it is 35 nm or less. The lower limit of the thickness of the conductive layer is preferably 10 nm.

The conductive layer may be transferred from the substrate to the retardation layer, and the conductive layer alone may be a constituent layer of the polarizing plate with a retardation layer, or may be laminated on the retardation layer as a laminate with the substrate (substrate with a conductive layer). Preferably, the substrate is optically isotropic, and therefore the conductive layer can be used in a polarizing plate with a retardation layer as an isotropic substrate with a conductive layer.

Any suitable isotropic substrate can be employed as the optically isotropic substrate (isotropic substrate). As a material constituting the isotropic substrate, for example, a material having a main skeleton of a resin having no conjugated system such as norbornene-based resin or olefin-based resin; and materials having it. When such a material is used, when an isotropic substrate is formed, it is possible to suppress the expression of a phase difference due to the orientation of molecular chains small. The thickness of the isotropic substrate is preferably 50 µm or less, and more preferably 35 µm or less. The lower limit of the thickness of the isotropic substrate is, for example, 20 µm.

The conductive layer and/or the conductive layer of the isotropic substrate with the conductive layer may be patterned as necessary. A conductive portion and an insulating portion may be formed by patterning. As a result, an electrode can be formed. The electrode may function as a touch sensor electrode that senses contact to the touch panel. Any suitable method can be employ|adopted as a patterning method. Specific examples of the patterning method include a wet etching method and a screen printing method.

[Example]

Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by these Examples. The measuring method of each characteristic is as follows. In addition, unless otherwise specified, 'part' and '%' in Examples are based on weight.

(1) glass transition temperature Tg

A solution in which the material constituting the protective layer used in Examples and Comparative Examples was dissolved in a predetermined solvent was applied to a substrate (PET film) with an applicator, and dried at 60° C. to form a coating film (thickness 40 μm). The obtained coating film was peeled from the base material, it cut out in strip shape, and it was set as the measurement sample. This measurement sample was used for DMA measurement, and Tg was measured. The measuring apparatus and measuring conditions were as follows.

(measuring device)

'DMS6100' manufactured by SII Nanotechnology

(Measuring conditions)

· Measurement temperature range: -80℃~150℃

· Temperature rising/falling rate: 2℃/min

· Measurement sample width: 10mm

· Distance between chucks: 20mm

・Measuring frequency: 1Hz

· Deformation amplitude: 10㎛

· Measurement atmosphere: N ₂ (250 mL/min)

(2) iodine adsorption amount

A solution in which the material constituting the protective layer used in Examples and Comparative Examples was dissolved in a predetermined solvent was applied to a substrate (PET film) with an applicator, and dried at 60° C. to form a coating film (thickness 40 μm). The obtained coating film was peeled from the base material, and it cut out to 1 cm x 1 cm (1 cm<2>), and it was set as the measurement sample. The measurement sample was subjected to a combustion IC method, and the amount of iodine in the sample was quantitatively analyzed. Specifically, it is as follows. The measurement sample was collected and weighed in a headspace vial (20 mL volume). Next, a vial (2 mL volume) containing 1 mL of an iodine solution (iodine concentration of 1% by weight, potassium iodide concentration of 7% by weight) was placed in this headspace vial and sealed tightly. After that, this headspace vial is heated in a dryer at 65° C. for 6 hours, the sample after heating is collected in a ceramic pot, and the gas generated by combustion using an automatic combustion device is collected in the absorption liquid, followed by quantitative analysis, The weight % of iodine was calculated|required. In addition, the equipment used was as follows.

· Automatic sample combustion device: 'AQF-2100H' manufactured by Mitsubishi Chemical Analytics

IC (anion): manufactured by Thermo Fisher Scientific, 'ICS-3000'

(3) color loss

From the polarizing plate with a retardation layer obtained in the Example and the comparative example, the test piece (50 mm x 50 mm) which makes the direction orthogonal to the absorption axis direction of a polarizer, and the absorption axis direction respectively opposing two sides were cut out. With the protective layer on the outside, the test piece is bonded to an alkali-free glass plate with an adhesive to make a test sample, and the test sample is left in an oven at 85° C. and 85% RH for 48 hours to heat and humidify, and a standard polarizing plate and cross nicol The color loss state of the polarizing plate with retardation layer after humidification at the time of arrange|positioning in a state was visually investigated, and the following reference|standard evaluated.

No problem: No color loss was confirmed.

Partial omission: Color fading was confirmed at the end.

Overall omission: color fading was remarkable over the entire polarizing plate.

(4) Single transmittance and polarization degree

From the polarizing plate with a retardation layer obtained in the Example and the comparative example, the test piece (50 mm x 50 mm) which makes the direction orthogonal to the absorption axis direction of a polarizer and the absorption axis direction respectively opposingly two sides were cut out. With the protective layer on the outside, the test piece was bonded to an alkali-free glass plate with an adhesive to make a test sample, and for the test sample, using a UV/visible spectrophotometer (manufactured by Japan Spectroscopy, product name 'V7100'), single transmittance (Ts), the parallel transmittance (Tp), and the orthogonal transmittance (Tc) were measured, and the polarization degree (P) was calculated|required by the following formula. At this time, the measurement light was incident from the protective layer side.

Polarization degree (P)(%)={(Tp-Tc)/(Tp+Tc)} ^1/2 × 100

In addition, said Ts, Tp, and Tc are the Y values which measured with the 2 degree field of view (C light source) of JIS Z 8701, and performed visibility correction|amendment. In addition, Ts and P are substantially characteristics of a polarizer.

Next, the polarizing plate with a retardation layer was left to stand in an oven at 85° C. and 85% RH for 48 hours to heat and humidify (heating test), and the single transmittance before the heating test (Ts ₀ ) and the single transmittance after the heating test (Ts ₄₈ ). , The amount of change in single transmittance (ΔTs) was calculated using the following formula.

ΔTs(%)=Ts ₄₈ -Ts ₀

Similarly, the polarization degree change amount (ΔP) was calculated from the polarization degree before the heating test (P ₀ ) and the polarization degree after the heating test (P _{48 ) using the following formula.}

ΔP(%)=P ₄₈ -P ₀

In addition, the heating test carried out similarly to the case of the said color loss, and produced and performed the test sample.

(5) frontal reflectance

From the polarizing plate with a retardation layer obtained in the Example and the comparative example, the test piece (50 mm x 50 mm) which makes the direction orthogonal to the absorption axis direction of a polarizer and the absorption axis direction respectively opposingly two sides were cut out. The test piece was bonded to an alkali-free glass plate with an adhesive so that the protective layer turned outward, and it was set as the test sample. This test sample was subjected to a 48 hour humidification test at 85° C., 85% RH. On a reflective plate (manufactured by Toray Film, trade name 'DMS-X42'; reflectance 86%), the test sample after the humidification test was placed so that the glass and the reflective plate faced (ie, the protective layer was on the outside). Then, the front reflectance was measured by the SCI method using a spectrophotometer (CM-2600d manufactured by Konica Minolta).

<Example 1>

1. Preparation of laminated body of polarizer/resin substrate

As the resin substrate, an amorphous isophthalic copolymerized polyethylene terephthalate film (thickness: 100 µm) having a long water absorption rate of 0.75% and a Tg of about 75°C was used. Corona treatment was performed on one side of the resin substrate.

Polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name 'Gosefaimer Z410') are mixed in a ratio of 9: 1 to 100 parts by weight of a PVA-based resin mixed with potassium iodide 13 weight part was added, and the PVA aqueous solution (coating liquid) was prepared.

The PVA aqueous solution was applied to the corona-treated surface of the resin substrate and dried at 60° C. to form a 13 μm-thick PVA-based resin layer to prepare a laminate.

The obtained laminate was uniaxially stretched at the free end by 2.4 times in the longitudinal direction (longitudinal direction) between rolls having different circumferential speeds in an oven at 130°C (air-assisted stretching treatment).

Next, the laminate was immersed in an insolubilization bath (a boric acid aqueous solution obtained by blending 4 parts by weight of boric acid with respect to 100 parts by weight of water) at a liquid temperature of 40°C for 30 seconds (insolubilization treatment).

Then, in a dyeing bath (aqueous solution of iodine obtained by mixing iodine and potassium iodide in a weight ratio of 1:7 with respect to 100 parts by weight of water) at a liquid temperature of 30°C, the single transmittance (Ts) of the finally obtained polarizer was 41.5% ± It was immersed for 60 seconds while adjusting the density|concentration so that it might become 0.1% (dyeing process).

Next, it was immersed in a crosslinking bath (a boric acid aqueous solution obtained by blending 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with respect to 100 parts by weight of water) at a liquid temperature of 40°C for 30 seconds (crosslinking treatment).

Thereafter, while immersing the laminate in a boric acid aqueous solution (boric acid concentration of 4.0 wt%) at a liquid temperature of 70 ° C., uniaxial stretching is performed between rolls having different circumferential speeds so that the total draw ratio is 5.5 times in the longitudinal direction (longitudinal direction). (underwater stretching treatment).

Thereafter, the laminate was immersed in a washing bath (aqueous solution obtained by blending 4 parts by weight of potassium iodide with respect to 100 parts by weight of water) having a liquid temperature of 20°C (washing treatment).

Thereafter, while drying in an oven maintained at 90°C, it was brought into contact with a heating roll made of SUS whose surface temperature was maintained at 75°C for about 2 seconds (dry shrinkage treatment). The shrinkage ratio in the width direction of the laminate by the drying shrinkage treatment was 5.2%.

In this way, the polarizer with a thickness of 5 micrometers was formed on the resin base material, and the laminated body of a polarizer/resin base material was produced. The single transmittance (initial single transmittance) (Ts ₀ ) of the polarizer was 41.5, and the polarization degree (initial polarization degree) (P ₀ ) was 99.996%.

2. Preparation of retardation film constituting retardation layer

2-1. Polymerization of polyester carbonate-based resins

Polymerization was carried out using a batch polymerization apparatus consisting of two vertical reactors equipped with stirring blades and a reflux condenser controlled at 100°C. Bis[9-(2-phenoxycarbonylethyl)fluoren-9-yl]methane 29.60 parts by mass (0.046 mol), isosorbide (ISB) 29.21 parts by mass (0.200 mol), spiroglycol (SPG) 42.28 mass Parts (0.139 mol), 63.77 parts by mass (0.298 mol) of ^{diphenyl carbonate (DPC), and 1.19 x 10 -2} parts by mass (6.78 x 10 ^{-5 mol) of calcium acetate monohydrate were added as a catalyst.} After replacing the inside of the reactor with reduced pressure nitrogen, heating was performed with a heating medium, and stirring was started when the internal temperature reached 100°C. The internal temperature was made to reach 220 degreeC 40 minutes after the start of temperature rise, and while controlling so that this temperature might be maintained, pressure reduction was started and it was set to 13.3 kPa in 90 minutes after reaching 220 degreeC. The phenol vapor produced by the polymerization reaction was introduced into a reflux condenser at 100° C., the monomer component contained in a small amount in the phenol vapor was returned to the reactor, and the phenol vapor that was not condensed was introduced into the condenser at 45° C. and recovered. After nitrogen was introduced into the first reactor and the pressure was returned to atmospheric pressure, the oligomerized reaction solution in the first reactor was transferred to the second reactor. Then, the temperature rise and pressure reduction in the 2nd reactor were started, and it was set as the internal temperature of 240 degreeC and the pressure of 0.2 kPa in 50 minutes. Thereafter, polymerization was allowed to proceed until a predetermined stirring power was reached. When a predetermined power was reached, nitrogen was introduced into the reactor and the pressure was restored, and the resulting polyester carbonate-based resin was extruded into water, and the strands were cut to obtain pellets.

2-2. Production of retardation film

After vacuum drying the obtained polyester carbonate-based resin (pellet) at 80 ° C. for 5 hours, a single screw extruder (manufactured by Toshiba Machinery Co., Ltd., cylinder set temperature: 250 ° C), T-die (width 200 mm, set temperature: 250 ° C), a cooling roll ( Setting temperature: 120-130 degreeC) and the film film forming apparatus provided with the winder were used to produce the 135-micrometer-thick elongate resin film. The obtained elongate resin film was extended|stretched by the extending|stretching temperature of 133 degreeC, and a draw ratio of 2.8 times in the width direction, and the 48-micrometer-thick retardation film was obtained. Re(550) of the obtained retardation film was 141 nm, Re(450)/Re(550) was 0.82, and Nz coefficient was 1.12.

3. Preparation of polarizing plate with retardation layer

The retardation film obtained in said 3. was bonded to the polarizer surface of the laminated body obtained in said 1. via the acrylic adhesive (5 micrometers in thickness). At this time, it bonded together so that the absorption axis of a polarizer and the slow axis of retardation film might make the angle of 45 degrees. The resin base material was peeled, and the polarizing plate with retardation layer containing the structure of retardation layer/polarizer was obtained.

20 parts of acrylic resin (30 mol% of lactone ring units) which is polymethyl methacrylate which has a lactone ring unit was melt|dissolved in 80 parts of methyl ethyl ketone, and the acrylic resin solution (20%) was obtained. This acrylic resin solution was applied to the polarizer surface of the polarizing plate obtained above using a wire bar, and the coating film was dried at 60° C. for 5 minutes to form a protective layer constituted as a solidified product of the coating film. The thickness of the protective layer was 3 μm, the Tg was 119° C., and the iodine adsorption amount was 0.25 wt%. In this way, the polarizing plate with a retardation layer which has the structure of a protective layer (solidified material of a coating film)/polarizer/retardation layer was obtained. The obtained polarizing plate with retardation layer was used for evaluation of said (3)-(5). In addition, the presence or absence of shrinkage after formation of the protective layer was visually observed. A result is shown in Table 1.

<Example 2>

The protective layer was carried out in the same manner as in Example 1, except that an acrylic resin of polymethyl methacrylate having a maleic anhydride unit (7 mol% of maleic anhydride units) was used instead of the acrylic resin of polymethyl methacrylate having a lactone ring unit. was formed. The thickness of the protective layer was 3 μm, and the Tg was 115°C. Except having used this protective layer, it carried out similarly to Example 1, and produced the polarizing plate with retardation layer. The obtained polarizing plate with retardation layer was used for evaluation similar to Example 1. A result is shown in Table 1.

<Example 3>

Protection was carried out in the same manner as in Example 1, except that 100% polymethyl methacrylate acrylic resin (manufactured by Kusumoto Chemical Co., Ltd., product name 'B-728') was used instead of polymethyl methacrylate acrylic resin having a lactone ring unit. layer was formed. The thickness of the protective layer was 3 μm, the Tg was 116° C., and the iodine adsorption amount was 0.34 wt%. Except having used this protective layer, it carried out similarly to Example 1, and produced the polarizing plate with retardation layer. The obtained polarizing plate with retardation layer was used for evaluation similar to Example 1. A result is shown in Table 1.

<Example 4>

In the same manner as in Example 1, protection was performed in the same manner as in Example 1, except that an acrylic resin of polymethyl methacrylate having a glutarimide ring unit (4 mol% of glutarimide ring units) was used instead of the acrylic resin of polymethyl methacrylate having a lactone ring unit. layer was formed. The thickness of the protective layer was 3 μm, the Tg was 103° C., and the adsorption amount of iodine was 2.3 wt%. Except having used this protective layer, it carried out similarly to Example 1, and produced the polarizing plate with retardation layer. The obtained polarizing plate with retardation layer was used for evaluation similar to Example 1. A result is shown in Table 1.

<Example 5>

A protective layer was formed in the same manner as in Example 1 except that an acrylic resin (20 mol% of lactone ring unit) which is another polymethyl methacrylate having a lactone ring unit was used. The thickness of the protective layer was 3 μm, the Tg was 104° C., and the iodine adsorption amount was 2.8 wt%. Except having used this protective layer, it carried out similarly to Example 1, and produced the polarizing plate with retardation layer. The obtained polarizing plate with retardation layer was used for evaluation similar to Example 1. A result is shown in Table 1.

<Example 6>

A protective layer was formed in the same manner as in Example 1, except that an acrylic resin that is a copolymer of methyl methacrylate/butyl methacrylate (molar ratio 80/20) was used instead of an acrylic resin that is polymethyl methacrylate having a lactone ring unit. . The thickness of the protective layer was 3 μm, the Tg was 95° C., and the iodine adsorption amount was 3.8 wt%. Except having used this protective layer, it carried out similarly to Example 1, and produced the polarizing plate with retardation layer. The obtained polarizing plate with retardation layer was used for evaluation similar to Example 1. A result is shown in Table 1.

<Example 7>

1. Preparation of laminated body of polarizer/resin substrate

It carried out similarly to Example 1, and produced the laminated body of a polarizer/resin base material.

2. Preparation of the first alignment-solidified layer and the second alignment-solidified layer constituting the retardation layer 10 g of a polymerizable liquid crystal exhibiting a nematic liquid crystal phase (manufactured by BASF, trade name 'Paliocolor LC242', represented by the following formula), and the polymerizable 3 g of a photopolymerization initiator for a liquid crystal compound (manufactured by BASF, trade name 'Irugacure 907') was dissolved in 40 g of toluene to prepare a liquid crystal composition (coating solution).

The surface of a polyethylene terephthalate (PET) film (thickness 38 micrometers) was rubbed using the rubbing cloth, and orientation treatment was performed. The direction of orientation treatment was made so that it might become a 15 degree direction as seen from the visual recognition side with respect to the direction of the absorption axis of a polarizer when bonding to a polarizing plate. The liquid crystal compound was orientated by coating the said liquid crystal coating liquid on the surface of this orientation treatment with a bar coater, and heating and drying at 90 degreeC for 2 minute(s). The liquid crystal layer formed in this way was irradiated with light of 1 mJ/cm 2 using a metal halide lamp, and the liquid crystal layer was cured to form the liquid crystal alignment solidified layer A on the PET film. The thickness of the liquid-crystal alignment solidification layer A was 2.5 micrometers, and the in-plane retardation Re(550) was 270 nm. Moreover, the liquid-crystal orientation solidification layer A showed the refractive index characteristic of nx>ny=nz.

A liquid-crystal alignment solidification layer B was formed on the PET film in the same manner as above except that the coating thickness was changed and the orientation treatment direction became a 75° direction when viewed from the visual side with respect to the direction of the absorption axis of the polarizer. The thickness of the liquid-crystal alignment solidification layer B was 1.5 micrometers, and in-plane retardation Re(550) was 140 nm. Moreover, the liquid-crystal orientation solidification layer B showed the refractive index characteristic of nx>ny=nz.

3. Preparation of polarizing plate with retardation layer

The liquid-crystal orientation-solidified layer A and the liquid-crystal orientation-solidified layer B obtained in said 2. were transcribe|transferred in this order to the polarizer surface of the laminated body of the polarizer/resin base material obtained in said 1.. At this time, transfer (bonding) was performed so that the angle between the absorption axis of the polarizer and the slow axis of the alignment-solidified layer A was 15°, and the angle formed between the absorption axis of the polarizer and the slow axis of the alignment-solidified layer B was 75°. . In addition, each transcription|transfer (bonding) was performed through the ultraviolet curing adhesive (1.0 micrometer in thickness). Next, the base material with an adhesive was pasted together on the surface of the orientation-solidified layer B for reinforcement. Next, the resin base material was peeled off, and the polarizing plate with a retardation layer containing the structure of polarizer / adhesive layer / retardation layer (1st orientation solidified layer / adhesive layer / 2nd orientation solidified layer) / base material with an adhesive was obtained.

Next, it carried out similarly to Example 3, and formed the protective layer on the polarizer surface of the polarizing plate with retardation layer. Finally, the base material with an adhesive layer was peeled, and the polarizing plate with a retardation layer containing the structure of a protective layer (solidified material of a coating film) / polarizer / retardation layer was obtained. The obtained polarizing plate with retardation layer was used for evaluation similar to Example 1. A result is shown in Table 1.

<Comparative Example 1>

Instead of an acrylic resin that is polymethyl methacrylate having a lactone ring unit, an acrylic resin that is a copolymer of methyl methacrylate / ethyl acrylate (molar ratio 55/45) (manufactured by Kusumoto Chemical Co., Ltd., product name 'B-722') was used Except that, a protective layer was formed in the same manner as in Example 1. The thickness of the protective layer was 3 μm, the Tg was 39° C., and the iodine adsorption amount was 1.7 wt%. Except having used this protective layer, it carried out similarly to Example 1, and produced the polarizing plate with retardation layer. When the obtained polarizing plate with retardation layer was used for evaluation of color loss, since it was defective ('total loss'), evaluation of single transmittance and polarization degree was not performed. A result is shown in Table 1.

<Comparative Example 2>

Instead of an acrylic resin that is polymethyl methacrylate having a lactone ring unit, an acrylic resin that is a copolymer of methyl methacrylate / butyl methacrylate (molar ratio 35/65) (manufactured by Kusumoto Chemical Co., Ltd., product name 'B-734') was used. A protective layer was formed in the same manner as in Example 1 except that it was used. The thickness of the protective layer was 3 μm, the Tg was 71° C., and the iodine adsorption amount was 12 wt%. Except having used this protective layer, it carried out similarly to Example 1, and produced the polarizing plate with retardation layer. When the obtained polarizing plate with a retardation layer was used for evaluation of color loss, since it was defective ("total loss"), evaluation of single transmittance and polarization degree was not performed. A result is shown in Table 1.

<Comparative Example 3>

A protective layer (cured product) was formed in the same manner as in Example 1 except that an ultraviolet curable acrylic resin (manufactured by Gongyeongsa Chemical, product name 'Light acrylate HPP-A', hydroxypivalate neopentyl glycol acrylic acid adduct) was used. . Specifically, a composition containing 97% by weight of the acrylic resin and 3% by weight of a photopolymerization initiator (Irugacure 907, manufactured by BASF) was applied on a polarizer, and the accumulated light amount was 300mJ/cm2 using a high-pressure mercury lamp in a nitrogen atmosphere. Ultraviolet rays were irradiated to form a cured layer (protective layer). The thickness of the protective layer was 3 μm, the Tg was 83° C., and the iodine adsorption amount was 6.6 wt%. Except having used this protective layer, it carried out similarly to Example 1, and produced the polarizing plate with retardation layer. The obtained polarizing plate with retardation layer was used for evaluation similar to Example 1. A result is shown in Table 1.

<Comparative Example 4>

Protected in the same manner as in Example 1, except that an ultraviolet curable acrylic resin (manufactured by Dong-A Synthesis, product name 'Aronix M-402', dipentaerythritol penta and hexaacrylate (pentaacrylate 30% to 40%)) was used. A layer (cured product) was formed. The formation method of the protective layer was the same as that of Comparative Example 3. The thickness of the protective layer was 3 μm. Except having used this protective layer, it carried out similarly to Example 1, and produced the polarizing plate with retardation layer. The obtained polarizing plate with retardation layer was used for evaluation similar to Example 1. A result is shown in Table 1.

<Comparative Example 5>

A protective layer (cured product) was formed in the same manner as in Example 1 except that an ultraviolet curable epoxy resin (manufactured by Daicel Corporation, product name 'Ceroxide 2021P') was used. Specifically, a composition containing 95% by weight of the epoxy resin and 5% by weight of a photopolymerization initiator (CPI-100P, manufactured by San Apro) is applied on a polarizer, and an integrated light quantity of 500mJ/cm 2 using a high-pressure mercury lamp in an air atmosphere was irradiated with ultraviolet light to form a cured layer (protective layer). The thickness of the protective layer was 3 μm, the Tg was 95° C., and the iodine adsorption amount was 9 wt%. Except having used this protective layer, it carried out similarly to Example 1, and produced the polarizing plate with retardation layer. The obtained polarizing plate with retardation layer was used for evaluation similar to Example 1. A result is shown in Table 1.

<Comparative Example 6>

A protective layer (solidified product of the coating film) was formed in the same manner as in Example 1 except that a water-based polyester-based resin (manufactured by Nippon Synthetic Chemicals, product name 'Polyester WR905') was used. The thickness of the protective layer was 3 mu m, and the adsorption amount of iodine was 12 wt%. Except having used this protective layer, it carried out similarly to Example 1, and produced the polarizing plate with retardation layer. When the obtained polarizing plate with retardation layer was used for evaluation of color loss, since it was defective ('total loss'), evaluation of single transmittance and polarization degree was not performed. A result is shown in Table 1.

<Comparative Example 7>

A protective layer (solidified product of the coating film) was formed in the same manner as in Example 1 except that a water-based polyurethane-based resin (manufactured by First Industrial Pharmaceutical Co., Ltd., product name 'Superflex SF210') was used. The thickness of the protective layer was 3 μm, the Tg was 107° C., and the iodine adsorption amount was 19 wt%. Except having used this protective layer, it carried out similarly to Example 1, and produced the polarizing plate with retardation layer. When the obtained polarizing plate with a retardation layer was used for evaluation of color loss, since it was defective ("total loss"), evaluation of single transmittance and polarization degree was not performed. A result is shown in Table 1.

<Comparative Example 8>

A protective layer (solidified product of the coating film) was formed in the same manner as in Example 1 except that a water-based polyurethane-based resin (manufactured by Unitica, product name 'Arrow Base SE1200') was used. The thickness of the protective layer was 3 μm, and the adsorption amount of iodine was 15 wt%. Except having used this protective layer, it carried out similarly to Example 1, and produced the polarizing plate with retardation layer. When the obtained polarizing plate with a retardation layer was used for evaluation of color loss, since it was defective ("total loss"), evaluation of single transmittance and polarization degree was not performed. A result is shown in Table 1.

[Table 1]

<Evaluation>

As is clear from Table 1, although the polarizing plate with a retardation layer of the embodiment of the present invention is very thin, deterioration of optical properties is suppressed even in a heated and humidified environment, and it is excellent in durability and does not shrink after formation of the protective layer , a polarizing plate with a retardation layer that can withstand practical use. Moreover, the polarizing plate with a retardation layer of the Example of this invention had very small front reflectance after a humidification test, and showed favorable antireflection characteristic. This indicates that, for example, when applied to an image display device including a metal layer such as an organic EL display device, there is an effect of preventing the penetration of external light by the metal layer.

Industrial Applicability

The polarizing plate with a retardation layer of this invention is used suitably for an image display apparatus. As an image display apparatus, For example, portable devices, such as a portable information terminal (PDA), a smart phone, a mobile phone, a watch, a digital camera, and a portable game machine; OA equipment such as computer monitors, notebook computers, and photocopiers; household electrical appliances such as video cameras, TVs, and microwaves; vehicle equipment such as a back monitor, a monitor for a car navigation system, and a car audio system; display devices such as digital signage and information monitors for commercial stores; security devices such as monitors for monitoring; Nursing/medical equipment, such as a nursing monitor and a medical monitor; is mentioned.

10: polarizer
20: protective layer
40: retardation layer
41: first floor
42: second floor
100: polarizer

Claims (11)

A polarizing plate comprising a polarizer and a protective layer disposed on one side of the polarizer, and a retardation layer disposed on the opposite side to the protective layer of the polarizing plate,
The polarizing plate with a retardation layer, wherein the protective layer is composed of a solidified product of a coating film of an organic solvent solution of a thermoplastic acrylic resin, and the glass transition temperature of the protective layer is 95°C or higher. According to claim 1,
The retardation layer is a single layer,
Re (550) of the retardation layer is 100 nm to 190 nm,
A polarizing plate with a retardation layer, wherein an angle between the slow axis of the retardation layer and the absorption axis of the polarizer is 40° to 50°. 3. The method of claim 2,
The polarizing plate with a retardation layer whose said retardation layer is a resin film. 3. The method of claim 2,
A polarizing plate with a retardation layer, wherein the retardation layer is an alignment-solidified layer of a liquid crystal compound. According to claim 1,
The retardation layer has a laminated structure of a first layer and a second layer,
Re (550) of the first layer is 200 nm to 300 nm, and the angle between its slow axis and the absorption axis of the polarizer is 10° to 20°,
A polarizing plate with a retardation layer, wherein Re (550) of the second layer is 100 nm to 190 nm, and an angle between its slow axis and an absorption axis of the polarizer is 70° to 80°. 6. The method of claim 5,
A polarizing plate with a retardation layer, wherein the first layer and the second layer are each a resin film. 6. The method of claim 5,
A polarizing plate with a retardation layer, wherein the first layer and the second layer are alignment-solidified layers of a liquid crystal compound, respectively. 8. The method according to any one of claims 1 to 7,
The thickness of the said protective layer is 10 micrometers or less, The polarizing plate with retardation layer. 9. The method according to any one of claims 1 to 8,
The polarizing plate with a retardation layer whose iodine adsorption amount of the said protective layer is 4.0 weight% or less. 10. The method according to any one of claims 1 to 9,
A polarizing plate with a retardation layer, wherein the thermoplastic acrylic resin comprises at least one selected from the group consisting of a lactone ring unit, a glutaric anhydride unit, a glutarimide unit, a maleic anhydride unit, and a maleimide unit. 11. The method according to any one of claims 1 to 10,
A polarizing plate with a retardation layer which is arrange|positioned on the visual recognition side of an image display apparatus, and the said protective layer is arrange|positioned on the visual recognition side.

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