JP2019151099A - Laminate film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated film in which retardation unevenness is unlikely to occur in a retardation film after peeling a protective film. SOLUTION: The laminated film (1) of the present invention is separated from a retardation film (20) having a liquid crystal retardation layer (3) on a base film (5) and the liquid crystal retardation layer (5). The liquid crystal retardation layer (3) includes a protective film (7) that is bonded to each other, and the liquid crystal retardation layer (3) is characterized in that the arithmetic mean waviness value Wa of the surface in contact with the protective film (7) is 70 nm or less. .. [Selection diagram] Fig. 1

Description

The present invention relates to a laminated film, and more particularly to a laminated film including a retardation film having a retardation layer on a base film and a protective film that is detachably bonded onto the retardation layer.

As a retardation film having a retardation layer such as a quarter retardation layer, for example, in Patent Document 1 (particularly paragraph 0163 of JP-A-2016-40603), a polymerizable liquid crystal compound is polymerized and cured on a substrate. What has a liquid crystal phase difference layer obtained is indicated, and in order to control a wrinkle and curl at the time of conveyance of this phase contrast film, pasting up a protection film so that exfoliation is also indicated.

JP2016-40603 (particularly paragraph 0163)

However, the laminated film in which the protective film is bonded onto the liquid crystal retardation layer of the retardation film having the liquid crystal retardation layer on the base film is likely to cause retardation unevenness in the retardation film after the protective film is peeled off. I understood that.

Therefore, the present inventor has intensively studied to develop a laminated film that hardly causes retardation unevenness after the protective film is peeled off, and as a result, has reached the present invention.

That is, the present invention comprises a retardation film having a liquid crystal retardation layer on a substrate film,
A laminated film comprising a protective film that is releasably bonded onto the liquid crystal retardation layer,
The liquid crystal retardation layer provides a laminated film characterized in that an arithmetic average waviness value Wa of a surface in contact with the protective film is 70 nm or less.

According to the laminated film of the present invention, retardation unevenness hardly occurs in the retardation film after the protective film is peeled off.

It is sectional drawing which shows typically the cross-sectional structure of an example of the laminated | multilayer film of this invention. It is sectional drawing which shows typically the cross-sectional structure of an example of the phase difference film obtained by peeling a protective film from the laminated | multilayer film of this invention. It is sectional drawing which shows typically the cross-sectional structure of an example of the polarizing plate obtained from the laminated | multilayer film of this invention.

As shown in the cross-sectional view of FIG. 1, the laminated film (1) of the present invention includes a retardation film (20). This retardation film (20) has a liquid crystal retardation layer (3) on a base film (5).

[Base film]
As the base film (5), a resin film formed from a resin is usually used. Examples of the resin forming the base film include methyl methacrylate resin, polyolefin resin, cyclic olefin resin, polyvinyl chloride resin, cellulose resin, styrene resin, acrylonitrile / butadiene / styrene resin, acrylonitrile / Styrene resin, polyvinyl acetate resin, polyvinylidene chloride resin, polyamide resin, polyacetal resin, polycarbonate resin, modified polyphenylene ether resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polysulfone resin , Polyethersulfone resin, polyarylate resin, polyamideimide resin, polyimide resin and the like.

These resins can be used alone or in combination of two or more. These resins can also be used after any appropriate polymer modification. Examples of the polymer modification include copolymerization, crosslinking, molecular terminal modification, stereoregularity control, and reaction between different polymers. Modifications such as mixing including the case involving the.

Among these, it is preferable to use a methyl methacrylate resin, a polyethylene terephthalate resin, a polyolefin resin, or a cellulose resin as the resin. The polyolefin resin here includes a chain polyolefin resin and a cyclic polyolefin resin.

Moreover, resin can also contain an additive as needed. Examples of the additive include a lubricant, an antiblocking agent, a heat stabilizer, an antioxidant, an antistatic agent, a light resistance agent, and an impact resistance improver.

Resin films formed from these resins are unstretched films obtained by forming a resin as a raw material, uniaxially stretched films obtained by performing uniaxial stretching treatment such as lateral stretching and longitudinal stretching after film formation, It is obtained by subjecting the film to longitudinal stretching and then lateral stretching, or biaxial stretching treatment such as sequential biaxial stretching treatment for transverse stretching and longitudinal stretching, and simultaneous biaxial stretching treatment for simultaneously performing longitudinal stretching and transverse stretching. It can be a biaxially stretched film or the like.

The film used as the base film can be easily obtained as a commercial product. If it is a methyl methacrylate-based resin film, the trade name is Sumipex (manufactured by Sumitomo Chemical Co., Ltd.) and Acrylite (registered trademark). , Acryprene (registered trademark) (manufactured by Mitsubishi Rayon Co., Ltd.), Delagras (registered trademark) (manufactured by Asahi Kasei Co., Ltd.), Paragrass (registered trademark), Comograss (registered trademark) (manufactured by Kuraray Co., Ltd.), and ACRYVIEWER (Registered trademark) (manufactured by Nippon Shokubai Co., Ltd.) and the like. If it is a polyolefin-type resin film, ZEONOR (registered trademark) (Nippon Zeon Co., Ltd.), Arton (registered trademark) (JSR Co., Ltd.), etc. are mentioned by a brand name, respectively. If it is a polyethylene terephthalate-type resin film, a Novaclear (trademark) (made by Mitsubishi Chemical Corporation), a Teijin A-PET sheet (made by Teijin Chemicals Ltd.), etc. will be mentioned, respectively. For polypropylene resin films, FILMAX CPP film (manufactured by FILMAX), Santox (registered trademark) (manufactured by Sun Tox Co., Ltd.), Tosero (registered trademark) (manufactured by Tosero Co., Ltd.), Toyobo Pyrene Film (Registered trademark) (manufactured by Toyobo Co., Ltd.), Treffan (registered trademark) (manufactured by Toray Film Processing Co., Ltd.), Nihon Polyace (manufactured by Nippon Polyace Co., Ltd.), and Dazai (registered trademark) FC (Futamura Chemical Co., Ltd.) Manufactured). In the case of cellulose-based resin films, Fujitac (registered trademark) TD (manufactured by Fuji Film Co., Ltd.), KC2UA and Konica Minolta TAC film KC (manufactured by Konica Minolta Co., Ltd.) and the like can be mentioned.

The base film (5) may exhibit a retardation. The base film (5) may have a retardation value for functioning as a λ / 4 plate or a λ / 2 plate. In the present invention, if the in-plane retardation value at a wavelength of 550 nm is 100 nm or more and 150 nm or less, it can be said that a retardation value of λ / 4 is indicated, and the in-plane retardation value at a wavelength of 550 nm is 200 nm or more and 300 nm or less. In other words, it can be said that a phase difference value of λ / 2 is shown.

[Liquid crystal retardation layer]
The retardation film (20) constituting the laminated film (1) of the present invention has a liquid crystal retardation layer (3) on the base film (5).

The liquid crystal retardation layer (3) is a layer including a layer obtained by polymerizing and curing a liquid crystal compound. The type of the liquid crystal compound is not particularly limited, but can be classified into a rod-shaped type (bar-shaped liquid crystal compound) and a disk-shaped type (disk-shaped liquid crystal compound, discotic liquid crystal compound) depending on the shape. Furthermore, there are a low molecular type and a high molecular type, respectively. Polymer generally means a polymer having a degree of polymerization of 100 or more (Polymer Physics / Phase Transition Dynamics, Masao Doi, 2 pages, Iwanami Shoten, 1992). In the present embodiment, any liquid crystal compound can be used. Further, two or more kinds of rod-like liquid crystal compounds, two or more kinds of disk-like liquid crystal compounds, or a mixture of a rod-like liquid crystal compound and a disk-like liquid crystal compound may be used.

As the rod-like liquid crystal compound, for example, those described in claim 1 of JP-T-11-53019 and paragraphs [0026] to [0098] of JP-A-2005-289980 are preferably used. it can. As the discotic liquid crystal compound, for example, those described in paragraphs [0020] to [0067] of JP-A-2007-108732 and paragraphs [0013] to [0108] of JP-A-2010-244038 are preferably used. Can be used.

The liquid crystal retardation layer is more preferably formed using a liquid crystal compound having a polymerizable group (rod-like liquid crystal compound or discotic liquid crystal compound). Thereby, the temperature change and humidity change of an optical characteristic can be made small.

The liquid crystal compound may be a mixture of two or more. In that case, it is preferable that at least one has two or more polymerizable groups. That is, the liquid crystal layer is preferably a layer formed by fixing a rod-like liquid crystal compound having a polymerizable group or a discotic liquid crystal compound having a polymerizable group by polymerization. In this case, it is no longer necessary to exhibit liquid crystallinity after forming a layer.

The kind of the polymerizable group contained in the rod-like liquid crystal compound or the disk-like liquid crystal compound is not particularly limited. For example, a functional group capable of an addition polymerization reaction such as a polymerizable ethylenically unsaturated group or a ring polymerizable group. Is preferred. More specifically, for example, (meth) acryloyl group, vinyl group, styryl group, allyl group and the like can be mentioned. Among these, a (meth) acryloyl group is preferable. The (meth) acryloyl group is a concept including both a methacryloyl group and an acryloyl group.

The method for forming the liquid crystal retardation layer is not particularly limited, and examples thereof include known methods. For example, it was obtained by applying a composition for forming an optically anisotropic layer containing a liquid crystal compound having a polymerizable group (hereinafter simply referred to as “composition”) on a base film to form a coating film. By subjecting the coating film to curing treatment (ultraviolet irradiation (light irradiation treatment) or heat treatment), a liquid crystal retardation layer can be formed to produce a retardation film.

The composition can be applied by a known method such as a wire bar coating method, an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, and a die coating method.

The composition may contain components other than the above-described liquid crystal compounds. For example, the composition may contain a polymerization initiator. As the polymerization initiator to be used, for example, a thermal polymerization initiator or a photopolymerization initiator is selected according to the type of the polymerization reaction. Examples of the photopolymerization initiator include α-carbonyl compounds, acyloin ethers, α-hydrocarbon-substituted aromatic acyloin compounds, polynuclear quinone compounds, combinations of triarylimidazole dimers and p-aminophenyl ketones. The amount of the polymerization initiator used is preferably 0.01 to 20% by mass and more preferably 0.5 to 5% by mass with respect to the total solid content of the composition.

In addition, the composition may contain a polymerizable monomer from the viewpoint of the uniformity of the coating film and the strength of the film. Examples of the polymerizable monomer include radically polymerizable or cationically polymerizable compounds. Among these, a polyfunctional radically polymerizable monomer is preferable.

In addition, as a polymerizable monomer, a thing copolymerizable with the liquid crystal compound containing the polymeric group mentioned above is preferable. Specific examples of the polymerizable monomer include those described in paragraphs [0018] to [0020] in JP-A-2002-296423. It is preferable that the usage-amount of a polymerizable monomer is 1-50 mass% with respect to the total mass of a liquid crystal compound, and it is more preferable that it is 2-30 mass%.

The composition may contain a surfactant from the viewpoint of the uniformity of the coating film and the strength of the film. Examples of the surfactant include conventionally known compounds. Of these, fluorine compounds are particularly preferred.

The composition may contain a solvent, and an organic solvent is preferably used. Examples of the organic solvent include amides (eg, N, N-dimethylformamide), sulfoxides (eg, dimethyl sulfoxide), heterocyclic compounds (eg, pyridine), hydrocarbons (eg, benzene, hexane), alkyl halides (eg, , Chloroform, dichloromethane), esters (eg, methyl acetate, ethyl acetate, butyl acetate), ketones (eg, acetone, methyl ethyl ketone), ethers (eg, tetrahydrofuran, 1,2-dimethoxyethane). Of these, alkyl halides and ketones are preferred. Two or more organic solvents may be used in combination.

The composition includes a vertical alignment accelerator such as a polarizer interface side vertical alignment agent and an air interface side vertical alignment agent, and a horizontal alignment accelerator such as a polarizer interface side horizontal alignment agent and an air interface side horizontal alignment agent. Such various orientation agents may be included. Furthermore, in addition to the above components, the composition may contain an adhesion improving agent, a plasticizer, a polymer, and the like.

The liquid crystal layer may include an alignment film having a function of defining the alignment direction of the liquid crystal compound. The alignment film generally contains a polymer as a main component. The polymer material for alignment film is described in many documents, and many commercially available products can be obtained.

The alignment film is usually subjected to a known alignment process. For example, a rubbing treatment, a photo-alignment treatment for applying polarized light, and the like can be mentioned. From the viewpoint of the surface roughness of the alignment film, the photo-alignment treatment is preferable.

The liquid crystal retardation layer (3) may be a positive C plate having a relationship of nx≈ny <nz. The liquid crystal retardation layer (3) may be a positive A plate having a relationship of nx> ny≈nz. When the liquid crystal retardation layer (3) is a positive A plate, the liquid crystal retardation layer (3) can be the above-mentioned λ / 4 plate or λ / 2 plate. Note that nx represents the refractive index in the slow axis direction in the film plane, ny represents the refractive index in the direction perpendicular to the slow axis in the film plane, and nz represents the refractive index in the thickness direction of the film. Represents a rate.

〔Protective film〕
In the laminated film (1) of the present invention, the protective film (7) is bonded onto the liquid crystal retardation layer (3) constituting the retardation film (20).

The protective film (7) may be formed from a single layer or a plurality of layers. It may contain an adhesive layer or it may not have an adhesive layer, but it can reduce defects such as adhesive residue in the liquid crystal retardation layer after peeling off the protective film. A protective film having a layer is preferred. Examples of the material for forming the protective film include the same resins as the material for forming the base film, and among them, polyolefin resins and polyethylene terephthalate resins are preferable.

What can be obtained as a commercial item can be used as a protective film. An example of a commercial product having a film of polyethylene terephthalate resin is “COSMO SHINE (registered trademark) A4100” manufactured by Toyobo Co., Ltd. Examples of commercially available products having a polyethylene resin film include “Force Field (registered trademark) 1035” manufactured by Tredegar Film Products Corporation and “Tretec (registered trademark)” manufactured by Toray Film Processing Co., Ltd.

The protective film (7) is detachably bonded onto the liquid crystal retardation layer (3).
When the protective film includes a pressure-sensitive adhesive layer, the adhesive strength may be appropriately selected for the releasable bonding, and the adhesive strength may be appropriately selected when the protective film has a self-adhesive layer.
By selecting and using a protective film having a relatively low adhesive strength, it can be bonded in a peelable manner.

[Arithmetic mean waviness value Wa of liquid crystal retardation layer]
In the laminated film (1) of the present invention, the liquid crystal retardation layer (3) is in contact with the protective film (7). In the liquid crystal retardation layer (3), the surface in contact with the protective film (7) is the surface opposite to the base film side, and the arithmetic average waviness value Wa thereof is 70 nm or less, preferably 50 nm or less, usually 0 nm or more. It is.

The arithmetic mean waviness value Wa of the liquid crystal retardation layer (3) is a cut-off value using a scanning white interference microscope (VS1000) manufactured by Hitachi High-Tech Science Co., Ltd. with a measurement range of X = 4000 μm or more and Y = 2000 μm or more. It can measure by the method of measuring on 100 micrometer conditions.

In order to set the arithmetic average waviness value Wa of the surface of the liquid crystal retardation layer (3) in contact with the protective film within the above range, for example, the surface of the protective film (7) on which the retardation film (20) is laminated is It is preferable that the following formula (1) is satisfied when the one-dimensional power spectrum with respect to the irregularity period f (μm) is H ² (f). The power spectrum can be measured by the method described in Examples described later. The lower limit of H ² (425) / H ² (212) is not particularly limited, but can be 2 or more.
H ² (425) / H ² (212) <10 (1)

In order to make the arithmetic mean waviness value Wa of the surface in contact with the protective film of the liquid crystal retardation layer (3) in the above range, for example, as the protective film (7), the arithmetic average of the surface on the side bonded to the liquid crystal retardation layer It is also preferable to select a waviness value Wa ₇ of 200 nm or less and paste it on the liquid crystal retardation layer (3). The arithmetic average waviness value Wa ₇ of the surface of the protective film (7) bonded to the liquid crystal retardation layer is preferably 150 nm or less, may be 100 nm or less, and is ideally 0 (zero). Although it is nm, it is usually 50 nm or more. The arithmetic average waviness value Wa ₇ of the protective film can be measured in the same manner as the liquid crystal retardation layer described above.

When the above-mentioned commercially available protective film is used as the protective film (7), the surface shape may vary depending on the grade or lot. Therefore, a protective film that satisfies the arithmetic average waviness value Wa ₇ is selected and used. . Further, when the surface shape is different between one surface and the other surface of the protective film (7), the surface on the side satisfying the arithmetic average waviness value Wa ₇ is bonded as the phase difference film (20) side. That's fine.

By overlaying the protective film (7) having such a surface shape on the retardation film (20) and then preferably pressing, the desired surface shape satisfying the arithmetic mean waviness Wa can be transferred to the retardation film. it can. The pressing pressure at the time of pressing is usually from 0.01 MPa to 0.02 MPa, the pressing temperature is usually from 50 ° C. to 70 ° C., and the pressing time is usually from 1 hour to 4 hours.

When the protective film (7) and the retardation film (20) are long, the two films (7, 20) are overlapped in a long shape, wound on a roll, and held at the above pressing temperature. May be. By increasing the tension at the time of winding on the roll, the pressing pressure that the protective film (7) and the retardation film (20) wound on the roll press against each other can be set to the above pressure, and the desired surface The shape can be transferred to a retardation film.

[Production method of laminated film]
The laminated film (1) of the present invention can be produced, for example, by a method including the following step (1) [liquid crystal retardation layer forming step] and step (2) [protective film bonding step].

Step (1): Applying a composition containing a liquid crystal compound on a base film and polymerizing it to form a liquid crystal retardation layer, and obtaining a retardation film (2): On the retardation film, Hereinafter, each process is demonstrated below, the process of bonding a protective film and obtaining a laminated film.

Step (1) [Liquid Crystal Phase Layer Formation Step]
Step (1) is a liquid crystal retardation layer forming step of producing a retardation film (20) by forming a liquid crystal retardation layer (3) on the base film (5).
Usually, first, an alignment film (not shown) for aligning the liquid crystal compound is formed on the base film (5). Examples of the alignment film include an alignment film containing an alignment polymer, a photo-alignment film, a groove alignment film that forms an uneven pattern and a plurality of grooves on the surface, and the like, and can be formed by a conventionally known method.

Next, a composition containing a liquid crystal compound is applied onto the alignment film, and if necessary, the solvent is dried, and then the liquid crystal compound is polymerized. Polymerization of the liquid crystal compound can be performed by a known method of polymerizing a compound having a polymerizable functional group. Specific examples include thermal polymerization and photopolymerization, and photopolymerization is preferred from the viewpoint of ease of polymerization. Photopolymerization can be carried out by irradiating the liquid crystal compound with active energy rays such as ultraviolet rays. The active energy ray may be irradiated from the base film side, from the liquid crystal compound side, or from both the base film side and the liquid crystal compound side.

Process (2) [protective film pasting process]
Step (2) is a protective film bonding step in which the protective film (7) is bonded onto the retardation film (20) obtained in the step (1) to obtain a laminated film (1). By laminating the protective film (7) on the retardation film (20), the retardation film (20) can be handled easily during storage and transportation, or the retardation film (20) can be laminated or rolled. It is possible to prevent the retardation films (20) from blocking each other when they are wound in a shape or to store them, or to prevent dust and the like from adhering to the retardation film (20) and causing defects. The protective film (7) is bonded onto the liquid crystal retardation layer (3) in the retardation film. When a long film is used as the protective film (7) and the retardation film (20), both films (7, 20) are sandwiched between a pair of bonding rolls, so that the long film remains Can be pasted. The laminated film (1) after bonding may be wound into a roll.

From the obtained laminated film, the protective film (7) can be peeled off to obtain the retardation film (20). The peeling method is not particularly limited.For example, when the protective film (7) and the retardation film (20) are bonded together in a long shape, the film is unwound from the roll, and the protective film (7) or the retardation film. The film (20) may be peeled off while being held on a roll. The peeled protective film (7) may be wound up on a roll. As shown in FIG. 3, the retardation film (20) thus obtained has a liquid crystal retardation layer (3) on a base film (5). This liquid crystal retardation layer (3) Has an arithmetic average waviness value Wa on the surface opposite to the base film (5) side of 70 nm or less, preferably 50 nm or less, and usually 0 nm or more.
The retardation film (20) after the protective film (7) is peeled may be bonded to the base film (3) side so that the protective film can be peeled. By sticking a protective film on the base film (3) side, the base film (3) can be protected and scratches can be prevented.
On the surface of the liquid crystal retardation layer (3) after peeling off the protective film (7), an adhesive for bonding the protective film (7), an antioxidant contained in the protective film (7), etc. May remain.

〔Polarizer〕
As shown in FIG. 3, the laminated film (1) of the present invention is formed, for example, by laminating a polarizer (4) on the base film (5) side of a retardation film (20) to form a polarizing plate (100). Can do. FIG. 3 schematically shows a cross section of the polarizing plate (100) thus obtained. The polarizing plate (100) has a configuration in which a retardation film (20) and a polarizer (4) are laminated via an adhesive layer (10). The retardation film (20) has a liquid crystal retardation layer (3) on the base film (5). The polarizer (4) is laminated on the base film (5) side of the retardation film (20). A protective film (7) may be detachably bonded onto the liquid crystal retardation layer (3) of the polarizing plate (100).

[Polarizer]
The polarizer (4) is, for example, a step of uniaxially stretching a polyvinyl alcohol resin film, a step of adsorbing a dichroic dye by dyeing the polyvinyl alcohol resin film with a dichroic dye, and a dichroic dye being adsorbed. The polyvinyl alcohol-based resin film is manufactured through a step of treating with a boric acid aqueous solution and a step of washing with water after the treatment with the boric acid aqueous solution.

As the polyvinyl alcohol resin, a saponified polyvinyl acetate resin can be used. Examples of the polyvinyl acetate resin include, in addition to polyvinyl acetate, which is a homopolymer of vinyl acetate, copolymers with other monomers copolymerizable with vinyl acetate. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group.

The saponification degree of the polyvinyl alcohol resin is usually about 85 to 100 mol%, preferably 98 mol% or more. This polyvinyl alcohol-based resin may be modified, and for example, polyvinyl formal and polyvinyl acetal modified with aldehydes can also be used. Moreover, the polymerization degree of polyvinyl alcohol-type resin is about 1,000-10,000 normally, and about 1,500-5,000 are preferable.

What formed the polyvinyl alcohol-type resin into a film is used as a raw film of a polarizer. The method for forming a polyvinyl alcohol-based resin can be formed by a known method.
The film thickness of the polyvinyl alcohol-based raw film is preferably about 5 to 35 μm, more preferably 5 to 20 μm, considering that the thickness of the obtained polarizer is 15 μm or less. When the film thickness of the original film is 35 μm or more, it is necessary to increase the draw ratio when producing the polarizer, and the dimensional shrinkage of the obtained polarizer tends to increase. On the other hand, when the film thickness of the raw film is 5 μm or less, the handling property at the time of stretching is lowered, and there is a tendency that problems such as cutting are likely to occur during production.

Uniaxial stretching of the polyvinyl alcohol-based resin film can be performed before dyeing of the dichroic dye, simultaneously with dyeing, or after dyeing. When uniaxial stretching is performed after dyeing, this uniaxial stretching may be performed before boric acid treatment or during boric acid treatment. Moreover, you may uniaxially stretch in these several steps.

In uniaxial stretching, it may be uniaxially stretched between rolls having different peripheral speeds, or may be uniaxially stretched using a hot roll. Further, the uniaxial stretching may be dry stretching in which stretching is performed in the air, or may be wet stretching in which stretching is performed in a state where a solvent is used and the polyvinyl alcohol-based resin film is swollen. The draw ratio is usually about 3 to 8 times.

As a method of dyeing the polyvinyl alcohol resin film with the dichroic dye, for example, a method of immersing the polyvinyl alcohol resin film in an aqueous solution containing the dichroic dye is employed. Specifically, iodine or a dichroic dye is used as the dichroic dye. In addition, it is preferable that the polyvinyl alcohol-type resin film performs the immersion process to water before a dyeing process.

When iodine is used as the dichroic dye, a method of dyeing a polyvinyl alcohol-based resin film in an aqueous solution containing iodine and potassium iodide is usually employed.
The content of iodine in this aqueous solution is usually about 0.01 to 1 part by weight per 100 parts by weight of water. The content of potassium iodide is usually about 0.5 to 20 parts by weight per 100 parts by weight of water. The temperature of the aqueous solution used for dyeing is usually about 20 to 40 ° C. Moreover, the immersion time (dyeing time) in this aqueous solution is usually about 20 to 1800 seconds.

On the other hand, when a dichroic dye is used as the dichroic dye, a method of immersing and dyeing a polyvinyl alcohol-based resin film in an aqueous solution containing a water-soluble dichroic dye is usually employed. The content of the dichroic dye in this aqueous solution is usually about 1 × 10 ⁻⁴ to 10 parts by weight and preferably about 1 × 10 ⁻³ to 1 part by weight per 100 parts by weight of water. This aqueous solution may contain an inorganic salt such as sodium sulfate as a dyeing assistant. The temperature of the aqueous dichroic dye solution used for dyeing is usually about 20 to 80 ° C. Moreover, the immersion time (dyeing time) in this aqueous solution is usually about 10 to 1,800 seconds.

The boric acid treatment after dyeing with a dichroic dye can usually be performed by immersing the dyed polyvinyl alcohol-based resin film in a boric acid-containing aqueous solution.

The amount of boric acid in the boric acid-containing aqueous solution is usually about 2 to 15 parts by weight and preferably 5 to 12 parts by weight per 100 parts by weight of water. When iodine is used as the dichroic dye, the boric acid-containing aqueous solution preferably contains potassium iodide. The amount of potassium iodide in the boric acid-containing aqueous solution is usually about 0.1 to 15 parts by weight and preferably about 5 to 12 parts by weight per 100 parts by weight of water. The immersion time in the boric acid-containing aqueous solution is usually about 60 to 1,200 seconds, preferably about 150 to 600 seconds, and more preferably about 200 to 400 seconds. The temperature of the boric acid-containing aqueous solution is usually 50 ° C or higher, preferably 50 to 85 ° C, and more preferably 60 to 80 ° C.

The polyvinyl alcohol resin film after the boric acid treatment is usually washed with water. The water washing treatment can be performed, for example, by immersing a boric acid-treated polyvinyl alcohol resin film in water. The temperature of water in the water washing treatment is usually about 5 to 40 ° C. Further, the immersion time is usually about 1 to 120 seconds.

After washing with water, a drying process is performed to obtain a polarizer. The drying process can be performed using a hot air dryer or a far infrared heater. The temperature of the drying treatment is usually about 30 to 100 ° C, and preferably 50 to 80 ° C. The time for the drying treatment is usually about 60 to 600 seconds, and preferably 120 to 600 seconds.

By the drying process, the moisture content of the polarizer is reduced to a practical level. The water content is usually 5 to 20% by weight, preferably 8 to 15% by weight. When the moisture content is less than 5% by weight, the flexibility of the polarizer is lost, and the polarizer may be damaged or broken after drying. On the other hand, if the moisture content exceeds 20% by weight, the thermal stability of the polarizer may be inferior.

Further, the stretching, dyeing, boric acid treatment, water washing step, and drying step of the polyvinyl alcohol resin film in the production process of the polarizer may be performed in accordance with, for example, the method described in JP2012-159778A. . In the method described in this document, a polyvinyl alcohol resin layer to be a polarizer is formed by coating a polyvinyl alcohol resin on a base film.

[Polarizer protective film]
The polarizer (4) may be laminated on the base film (5) as a single layer as it is, but is usually laminated on the base film (5) after being laminated with a polarizer protective film (not shown). The
The polarizer protective film is composed of a resin film and can be composed of a transparent resin film. In particular, it is preferable to use a material that is excellent in transparency, mechanical strength, thermal stability, moisture shielding properties, and the like. In this specification, the transparent resin film means a resin film having a single transmittance of 80% or more in the visible light region.

The resin for forming the polarizer protective film is not particularly limited. For example, methyl methacrylate resin, polyolefin resin, cyclic olefin resin, polyvinyl chloride resin, cellulose resin, styrene resin , Acrylonitrile butadiene styrene resin, acrylonitrile styrene resin, polyvinyl acetate resin, polyvinylidene chloride resin, polyamide resin, polyacetal resin, polycarbonate resin, modified polyphenylene ether resin, polybutylene terephthalate Examples include films made of resins, polyethylene terephthalate resins, polysulfone resins, polyethersulfone resins, polyarylate resins, polyamideimide resins, polyimide resins, and the like. These resin films are a film formed from a raw material resin, a uniaxially stretched film obtained by transverse stretching after film formation, a biaxially stretched film obtained by longitudinally stretching after film formation and then transversely stretching, etc. be able to.

These resins can be used alone or in combination of two or more. These resins can also be used after any appropriate polymer modification. Examples of the polymer modification include copolymerization, crosslinking, molecular terminal modification, stereoregularity control, and reaction between different polymers. Modifications such as mixing including the case involving the.

Among these, as a material for the polarizer protective film, it is preferable to use a methyl methacrylate resin, a polyethylene terephthalate resin, a polyolefin resin, or a cellulose resin. The polyolefin resin here includes a chain polyolefin resin and a cyclic polyolefin resin.

Commercially available products can be easily obtained as the polarizer protective film. For methyl methacrylate resin films, Sumipex (manufactured by Sumitomo Chemical Co., Ltd.) and Acrylite (registered trademark) are used. ), Acryprene (registered trademark) (manufactured by Mitsubishi Rayon Co., Ltd.), Delagras (registered trademark) (manufactured by Asahi Kasei Corporation), Paragrass (registered trademark), Comograss (registered trademark) (manufactured by Kuraray Co., Ltd.), and Examples include ACRYVIEWER (registered trademark) (manufactured by Nippon Shokubai Co., Ltd.). If it is a polyolefin-type resin film, ZEONOR (registered trademark) (Nippon Zeon Co., Ltd.), Arton (registered trademark) (JSR Co., Ltd.), etc. are mentioned by a brand name, respectively. If it is a polyethylene terephthalate-type resin film, a Novaclear (trademark) (made by Mitsubishi Chemical Corporation), a Teijin A-PET sheet (made by Teijin Chemicals Ltd.), etc. will be mentioned, respectively. For polypropylene resin films, FILMAX CPP film (manufactured by FILMAX), Santox (registered trademark) (manufactured by Sun Tox Co., Ltd.), Tosero (registered trademark) (manufactured by Tosero Co., Ltd.), Toyobo Pyrene Film (Registered trademark) (manufactured by Toyobo Co., Ltd.), Treffan (registered trademark) (manufactured by Toray Film Processing Co., Ltd.), Nihon Polyace (manufactured by Nippon Polyace Co., Ltd.), and Dazai (registered trademark) FC (Futamura Chemical Co., Ltd.) Manufactured). In the case of cellulose-based resin films, Fujitac (registered trademark) TD (manufactured by Fuji Film Co., Ltd.), KC2UA and Konica Minolta TAC film KC (manufactured by Konica Minolta Co., Ltd.) and the like can be mentioned.

Moreover, the polarizer protective film can also contain an additive as needed. Examples of the additive include a lubricant, an antiblocking agent, a heat stabilizer, an antioxidant, an antistatic agent, a light resistance agent, and an impact resistance improver.

The thickness of the polarizer protective film may be 1 to 50 μm, 10 to 40 μm, or 10 to 35 μm.

Prior to bonding with the polarizer, the polarizer protective film may be subjected to saponification treatment, corona treatment, plasma treatment or the like. The polarizer protective film can be further provided with functional layers such as a conductive layer, a hard coat layer, an antiglare layer and a low reflection layer.

The polarizer protective film is usually laminated with the polarizer (4) through a polarizer adhesive layer (not shown). The polarizer adhesive layer is a layer for bonding the polarizer protective film and the polarizer, and is a layer obtained by curing the adhesive. The adhesive may be an active energy ray curable adhesive or an aqueous adhesive. The polarizer protective film may be laminated on both sides of the polarizer (4), or may be laminated only on one side.

[Adhesive layer]
In the polarizing plate (100) shown in FIG. 2, the base film (5) and the polarizer (4) are laminated via an adhesive layer (10). The adhesive layer (10) is a layer in which the adhesive is cured. The adhesive may be an active energy ray-curable adhesive or a water-based adhesive. The adhesive layer (10) may be laminated with the polarizer (4) through the polarizer protective film or a polarizer adhesive layer for laminating it with the polarizer.

An active energy ray-curable adhesive refers to an adhesive that cures when irradiated with an active energy ray such as an electron beam or ultraviolet ray. For example, an adhesive containing a polymerizable compound and a photopolymerization initiator, or a photoreactive resin. And those containing a binder resin and a photoreactive crosslinking agent. Examples of the polymerizable compound include a photocurable epoxy compound; a photocurable vinyl compound such as a photocurable acrylic compound; and a photocurable urethane compound. Examples of the photopolymerization initiator include a cationic photopolymerization initiator (for example, when using a photocurable epoxy compound) and a photoradical polymerization initiator (for example, when using a photocurable acrylic compound). .

The water-based adhesive is an adhesive layer that is cured by drying the water contained therein, and examples thereof include an adhesive made of a polyvinyl alcohol-based resin aqueous solution, and a water-based two-component urethane emulsion adhesive. Among these, a water-based adhesive composed of a polyvinyl alcohol-based resin aqueous solution is preferably used.

Polyvinyl alcohol resins include vinyl alcohol homopolymers obtained by saponifying polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith. A polyvinyl alcohol copolymer obtained by saponifying a polymer or a modified polyvinyl alcohol polymer obtained by partially modifying the hydroxyl group thereof can be used. The water-based adhesive can include additives such as polyvalent aldehydes, water-soluble epoxy compounds, melamine compounds, zirconia compounds, and zinc compounds.

The adhesive may contain an additive. Examples of the additive include an ion trap agent, an antioxidant, a chain transfer agent, a sensitizer, a tackifier, a thermoplastic resin, a filler, a flow regulator, a plasticizer, and an antifoaming agent.

The thickness of the adhesive layer (10) is, for example, 5 μm or less and preferably 2 μm or less from the viewpoint of reducing shrinkage when the adhesive is cured or drying and easily reducing the unevenness of the polarizing plate. 1 micrometer or less may be sufficient. Further, from the viewpoint of developing sufficient adhesive force, the thickness of the adhesive layer is usually 0.01 μm or more.

[Production method of polarizing plate]
Such a polarizing plate can be produced, for example, by a method including the following step (3) [protective film peeling step] and step (4) [retardation film laminating step].

Step (3) [Protective film peeling step]
Step (3) is a step of peeling off the protective film from the laminated film to obtain a retardation film.
The peeling method is not particularly limited. For example, when the laminated film is long, the peeling method may be carried out while holding the protective film or the retardation film on a roll. Moreover, you may wind up the peeled protective film.

Process (4) [Polarizer pasting process]
Step (4) is a step of obtaining a polarizing plate by laminating a polarizer on a retardation film via an adhesive.
The adhesive may be applied to the retardation film, may be applied to the polarizer, or may be applied to both the retardation film and the polarizer. Moreover, the surface by the side of a base film may be sufficient as the bonding surface to the polarizer in a phase difference film, and the surface by the side of a liquid crystal phase difference layer may be sufficient as it. When a water-based adhesive is used as the adhesive, the retardation film and the polarizer can be bonded by drying. When an active energy ray-curable adhesive is used as the adhesive, the retardation film and the polarizer can be bonded by irradiating active energy rays such as ultraviolet rays.

When using an aqueous adhesive, drying can be performed by, for example, introducing the film after pasting into a drying furnace. The drying temperature (temperature of the drying furnace) is preferably 30 to 90 ° C.
When it is lower than 30 ° C., the retardation film and the polarizer tend to be peeled off easily. On the other hand, when the drying temperature exceeds 90 ° C., the polarizing performance of the polarizer may be deteriorated by heat. The drying time can be about 10 to 1000 seconds.

After the drying step, a curing step of curing at room temperature or slightly higher temperature, for example, at a temperature of about 20 to 45 ° C. for about 12 to 600 hours may be provided. The curing temperature is generally set lower than the drying temperature.

The active energy ray may be irradiated from the retardation film side, may be irradiated from the polarizer side, or may be irradiated from both the retardation film side and the polarizer side.

The irradiation intensity of the active energy ray to the active energy ray curable adhesive is appropriately determined depending on the composition of the active energy ray curable adhesive, but the irradiation intensity in the wavelength region effective for the activation of the polymerization initiator is 0. It is preferably set to be 1 to 6000 mW / cm ² . When the irradiation intensity is 0.1 mW / cm ² or more, the reaction time does not become too long, and when it is 6000 mW / cm ² or less, the heat radiated from the radiation source and the active energy ray curable adhesive are cured. There is little risk of yellowing of the active energy ray-curable adhesive or deterioration of the polarizer due to heat generation.

The light irradiation time for the active energy ray-curable adhesive is also appropriately determined depending on the composition of the active energy ray-curable adhesive, but the integrated light amount expressed as the product of the irradiation intensity and the irradiation time is 10 to 10,000 mJ. It is preferably set to be / cm ² . When the integrated light quantity is 10 mJ / cm ² or more, a sufficient amount of active species derived from the polymerization initiator can be generated to advance the curing reaction more reliably, and when it is 10000 mJ / cm ² or less, the irradiation time is long. It does not become too much, and good productivity can be maintained.

When laminating a polarizer on a retardation film, the surface of the retardation film is subjected to plasma treatment, corona treatment, ultraviolet irradiation treatment, flame (flame) treatment, saponification in order to improve adhesion to the polarizer. Surface treatment such as treatment (easy adhesion treatment) can be performed. For example, when the retardation film contains a cyclic polyolefin resin, it is preferable to perform plasma treatment or corona treatment. Further, when the retardation film is made of a cellulose ester resin, it is preferable to perform a saponification treatment. Examples of the saponification treatment include a method of immersing in an alkaline aqueous solution such as sodium hydroxide or potassium hydroxide.

In the step (4), the polarizer may be bonded to the retardation film as a single layer. Moreover, a polarizing plate can also be obtained by laminating a polarizer protective film on a polarizer in advance and bonding it to a retardation film. Examples of the method for bonding the protective film and the polarizer include the same method as the method for bonding the retardation film and the polarizer. Moreover, a protective film, a polarizer, and a phase difference film can be bonded together to obtain a polarizing plate.

The step (3) [protective film peeling step] and the step (4) [polarizer bonding step] are performed in this order to peel the protective film [step (3)], and then the retardation film. A polarizer may be bonded together [Step (4)], or in the reverse order, that is, after the retardation film and the polarizer are bonded in Step (4), the protective film is bonded in Step (3). It may be peeled off. That is, the order of the step (3) and the step (4) is arbitrary.

(Adhesive layer)
The polarizing plate (100) shown in FIG. 2 may further include an adhesive layer (6) on the retardation film (20) side. The pressure-sensitive adhesive layer (6) is a layer made of a pressure-sensitive adhesive, and the polarizing plate (100) can be bonded to an image display element such as a liquid crystal cell via the pressure-sensitive adhesive layer (6). The thickness of the pressure-sensitive adhesive layer is usually 5 μm to 25 μm, preferably 10 μm to 25 μm.

Examples of the adhesive that forms the adhesive layer (6) include acrylic polymers, silicone polymers, polyesters, polyurethanes, polyamides, polyvinyl ethers, vinyl acetate / vinyl chloride copolymers, modified polyolefins, epoxy systems, fluorine systems, Those having a base polymer of a rubber-based polymer such as natural rubber or synthetic rubber can be appropriately selected and used. As the pressure-sensitive adhesive, those having excellent optical transparency, moderate wettability, cohesiveness and adhesive pressure-sensitive adhesive properties, and excellent weather resistance and heat resistance are particularly preferable.

Various other additives may be blended in the adhesive. Examples of the additive include a silane coupling agent and an antistatic agent.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not prescribed | regulated by these examples. In the examples, “%” and “part” representing the content or amount used are based on weight unless otherwise specified. The evaluation methods used in the examples are as follows.

(1) Thickness:
Measurement was performed using a digital micrometer MH-15M manufactured by Nikon Corporation.

(2) In-plane retardation Re and thickness direction retardation Rth:
It measured with the light of wavelength 590nm in 23 degreeC using the phase difference meter based on a parallel Nicol rotation method, and KOBRA-WPR by Oji Scientific Instruments.

(3) One-dimensional power spectrum for the period f (μm) of the surface of the protective film: H ² (f)
Surface irregularities were scanned using PLμNEOX (Sensofa Japan), which is a confocal interference microscope. The obtained unevenness data was analyzed, and H ² (212) and H ² (425) at a period of 212 μm and a period of 425 μm were calculated.

(4) Arithmetic mean swell value: Wa ₇ and Wa
Using the scanning white interference microscope VS1000 (manufactured by Hitachi High-Tech Science Co., Ltd.), for the protective film used in each example, the arithmetic average waviness value Wa ₇ of the surface to be bonded to the liquid crystal retardation layer is It was measured. Similarly, for the laminated film obtained in each Example, the protective film was peeled off, and the arithmetic average waviness value Wa of the exposed liquid crystal retardation layer was measured. Note that the measurement range was X = 4000 μm or more, Y = 2000 μm or more, and the cutoff value was 100 μm.

(5) Evaluation of phase difference unevenness On the backlight, two polarizing plates are arranged in parallel to each other and in a crossed Nicol relationship in which the absorption axes are orthogonal to each other. The retardation film obtained in the example was placed between the two polarizing plates in a state where the protective film was peeled off in parallel with the two polarizing plates, and then the backlight was turned on. Then, while observing the light passing through the polarizing plate, the retardation film and the polarizing plate from the front with the naked eye, the retardation film is rotated in the plane and fixed at a position where the transmitted light is darkest. Thereafter, the polarizing plate far from the backlight is visually inspected from an angle of 30 to 60 degrees from the front to determine whether or not phase difference unevenness (lightness unevenness) can be visually recognized.

Reference example 1
The following members were prepared.
[Polarizer]
(1) Primer layer forming step Polyvinyl alcohol powder (“Z-200” manufactured by Nippon Synthetic Chemical Industry Co., Ltd., average polymerization degree 1100, saponification degree 99.5 mol%) is dissolved in hot water at 95 ° C. to obtain a concentration. A 3% by weight aqueous polyvinyl alcohol solution was prepared. The resulting aqueous solution was mixed with a crosslinking agent (“Smiles Resin 650” manufactured by Taoka Chemical Co., Ltd.) at a ratio of 5 parts by weight with respect to 6 parts by weight of the polyvinyl alcohol powder to obtain a primer layer forming coating solution. Obtained.

An unstretched polypropylene (PP) film (melting point: 163 ° C.) having a thickness of 90 μm is prepared, and after corona treatment is performed on one surface thereof, the above-mentioned primer layer forming coating solution is applied to the corona-treated surface using a small-diameter gravure coater. Was applied and dried at 80 ° C. for 10 minutes to form a primer layer having a thickness of 0.2 μm to obtain a PP film with a primer layer.

(2) Preparation of laminated film Polyvinyl alcohol powder (“PVA124” manufactured by Kuraray Co., Ltd., average polymerization degree 2400, saponification degree 98.0 to 99.0 mol%) was dissolved in hot water at 95 ° C. to a concentration of 8 A weight% aqueous polyvinyl alcohol solution was prepared and used as a coating liquid for forming a polyvinyl alcohol-based resin layer.

The primer layer surface of the primer-coated PP film prepared in (1) above is coated with the above-mentioned coating solution for forming a polyvinyl alcohol-based resin layer using a lip coater, and then dried at 80 ° C. for 20 minutes. A polyvinyl alcohol resin layer was formed on the layer to obtain a laminated PP film composed of PP film / primer layer / polyvinyl alcohol resin layer.

(3) Production of stretched film The laminated PP film produced in (2) above was subjected to 5.8-fold free end uniaxial stretching at 160 ° C. using a floating longitudinal uniaxial stretching apparatus, and the stretched PP film was Obtained. The thickness of the stretched polyvinyl alcohol resin layer was 6.1 μm.

(4) Production of Polarizing Laminated PP Film The stretched PP film produced in (3) above was dyed at 30 ° C. containing iodine and potassium iodide (0.6 parts by weight iodine per 100 parts by weight water, iodine 10 parts by weight of potassium halide). After the polyvinyl alcohol resin layer was dyed for about 180 seconds, the excess dyeing aqueous solution was washed away with pure water at 10 ° C.

A first crosslinking aqueous solution containing 78 ° C containing boric acid (containing 9.5 parts by weight of boric acid per 100 parts by weight of water) for 120 seconds, and then a second crosslinking at 70 ° C containing boric acid and potassium iodide. A crosslinking treatment was performed by immersing in an aqueous solution (containing 9.5 parts by weight of boric acid and 4 parts by weight of potassium iodide per 100 parts by weight of water) for 60 seconds. Thereafter, the film was washed with 10 ° C. pure water for 10 seconds, and finally dried at 40 ° C. for 300 seconds to obtain a polarizing laminated PP film comprising PP film / primer layer / polarizer (4).

[Polarizer protective film]
A cyclic olefin resin film with a hard coat layer in which a hard coat layer was provided on one side of a cyclic olefin resin film of Nippon Zeon Co., Ltd. was prepared. The thickness was 50 μm.

〔Protective film〕
The following three types of protective films (7) were prepared. All are protective films containing a polyethylene resin and having a self-adhesive layer as a surface layer.
Protective film A: “Force Field 1035” manufactured by Tredegar
Protective film B: “Tretec (registered trademark) 7332K” manufactured by Toray Film Processing Co., Ltd.
Protective film C: “Tretec (registered trademark) 7832C” manufactured by Toray Film Processing Co., Ltd.

[Phase difference film]
A cyclic olefin resin film manufactured by Nippon Zeon Co., Ltd. was prepared as the base film (5). This base film (5) was long and had a thickness of 20 μm. This base film (5) was a λ / 4 plate. One side of the base film (5) was subjected to corona treatment. The composition for vertical alignment films was applied to the surface subjected to the corona treatment so that the film thickness became 1 μm. The coating film was heat-treated at 100 ° C. for 120 seconds to form an alignment film. As the composition for the vertical alignment film, Sun Ever SE610 manufactured by Nissan Chemical Co., Ltd. was used.

A composition containing the prepared photopolymerizable nematic liquid crystal compound (manufactured by Merck & Co., RMM28B) was applied on the alignment film formed above. The composition contains propylene glycol monomethyl ether acetate (PGMEA) as a solvent and Irgacure (Irg-907) as a photopolymerization initiator. The composition of this composition is as follows.
Photopolymerizable nematic liquid crystal compound [RMM28B]: 20 parts by weight Photopolymerization initiator [Irgacure (Irg-907)]: 1 part by weight Solvent [propylene glycol monomethyl ether acetate]: 80 parts by weight

The coated layer after coating was dried at a temperature of 90 ° C. for 120 seconds. Thereafter, the liquid crystal compound was polymerized by ultraviolet (UV) irradiation to form a liquid crystal retardation layer (3) in which the liquid crystal compound having a thickness of 1 μm was cured (the total thickness of the liquid crystal retardation layer was 2 μm). The liquid crystal retardation layer (3) was a positive C plate. In this way, a retardation film (20) composed of the base film (5) and the liquid crystal retardation layer (3) was obtained. The elastic modulus of the retardation film was 1900 MPa and 2300 MPa in the MD direction and the TD direction at 23 ° C., respectively. This retardation film (20) can function as a λ / 4 wavelength plate in the wavelength region of visible light, and also exhibits a retardation in the thickness direction.

[Example 1]
(Manufacture of laminated film)
Retardation film (20) obtained above so that the surface which measured the surface shape shown in Table 1 may become a bonding surface with liquid crystal phase difference layer (3) about protective film A (7) prepared above. The laminated film (1) [protective film A (7) / liquid crystal retardation layer (3) / base film (5)] having the structure shown in FIG. 1 is bonded onto the liquid crystal retardation layer (3). Obtained.

30 laminated films (1) [protective film A (7) / liquid crystal retardation layer (3) / base film (5)] obtained above were prepared, and these were layered together, pressing pressure 0.017 MPa, pressing When the arithmetic mean undulation value Wa of the surface of the liquid crystal retardation layer (3) which appeared after pressing at a temperature of 60 ° C. for 3 hours and then peeling off the protective film A (7) was measured, it was 55 nm.
When the retardation unevenness of the retardation film (20) constituting the polarizing plate (100) was evaluated, the retardation unevenness could not be confirmed visually.

(Manufacture of polarizing plates)
The surface of the polarizer protective film prepared above [cyclic olefin resin film with hard coat layer] opposite to the hard coat layer was subjected to corona treatment. An ultraviolet curable adhesive was applied to the corona-treated surface using a small-diameter gravure coater. The composition of this ultraviolet curable adhesive is as follows.
3 ′, 4′-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (trade name “CEL2021P”, manufactured by Daicel Corporation): 70 parts by weight,
Neopentyl glycol diglycidyl ether [trade name “EX-211”, manufactured by Nagase ChemteX Corporation]: 20 parts by weight,
2-ethylhexyl glycidyl ether [trade name “EX-121”, manufactured by Nagase ChemteX Corporation]: 10 parts by weight,
Photocationic polymerization initiator [trade name “CPI-100P”, manufactured by San Apro Co., Ltd.]: 2.25 parts by weight After coating, using the bonding roll, the polarized light obtained above via an ultraviolet curable adhesive A polarizer protective film was bonded onto the polarizer (4) of the conductive laminated PP film. Next, the ultraviolet curable adhesive is cured by ultraviolet irradiation to form a polarizer adhesive layer, and is composed of a polarizer protective film / polarizer adhesive layer / polarizer (4) / primer layer / PP film. A laminated film was obtained. The thickness of the polarizer adhesive layer of this bonding film was 0.8 μm.

The PP film was peeled off from the obtained laminated film. The PP film was easily peeled off to obtain a polarizing plate with a single-sided polarizer protective film having a layer constitution of polarizer protective film / polarizer adhesive layer / polarizer (4) / primer layer.

Corona treatment is performed on the base film (5) [cyclic olefin resin film] in the laminated film (1) obtained above. The same ultraviolet curable adhesive as described above is applied to the corona-treated surface using a small-diameter gravure coater. After coating, the laminated film (1) is pasted on the primer layer of the polarizing plate with a single-sided polarizer protective film through a UV curable adhesive using a bonding roll, and UV curable by UV irradiation. The adhesive is cured to form an adhesive layer (10).

After that, when protective film A (7) is peeled off, polarizer protective film / polarizer adhesive layer / polarizer (4) / primer layer / adhesive layer (10) / base film (5) / liquid crystal retardation layer A polarizing plate (100) comprising (3) can be obtained (FIG. 2). This polarizing plate (100) has no unevenness due to retardation unevenness of the retardation film, and exhibits uniform polarization performance over the entire surface.

[Example 2]
A laminated film (1) was prepared in the same manner as in Example 1 except that the protective film C was used in place of the protective film A, and 30 laminated films (1) obtained were laminated. When the arithmetic average waviness value Wa of the surface of the liquid crystal phase difference layer (3) that appeared after peeling off the protective film A (7) was measured in the same manner as described above, it was 65 nm.
When the retardation unevenness of the retardation film (20) constituting the polarizing plate (100) was evaluated, the retardation unevenness could not be confirmed visually.

[Comparative Example 1]
A laminated film (1) was produced in the same manner as in Example 1 except that the protective film B was used in place of the protective film A, and 30 laminated films (1) obtained were laminated. The arithmetic average undulation value Wa of the surface of the liquid crystal phase difference layer (3) that appeared after pressing in the same manner and then peeling off the protective film A (7) was 84 nm.
When the retardation unevenness of the retardation film (20) was evaluated, the retardation unevenness was visually confirmed.

The polarizing plate (100) obtained by operating in the same manner as in Example 1 except that the laminated film obtained above was used instead of the laminated film obtained in Example 1, was caused by the retardation of the retardation film (20). Causes uneven polarization performance.

1: Laminated film 3: Liquid crystal retardation layer 4: Polarizer 6: Adhesive layer 5: Base film 7: Protective film
10: Adhesive layer
20: Retardation film

Claims (5)

A retardation film having a liquid crystal retardation layer on a substrate film;
A laminated film comprising a protective film that is releasably bonded onto the liquid crystal retardation layer,
The laminated film, wherein the liquid crystal retardation layer has an arithmetic average waviness value Wa of 70 nm or less on a surface in contact with the protective film. It is the method of manufacturing the laminated | multilayer film of Claim 1 by bonding a protective film on the said liquid crystal phase difference layer of the phase difference film which has a liquid crystal phase difference layer on a base film so that peeling is possible,
The surface of the protective film on which the retardation film is laminated has the formula (1) when the one-dimensional power spectrum with respect to the period f (μm) of the surface irregularities is H ² (f).
H ² (425) / H ² (212) <10 (1)
The manufacturing method of the said laminated | multilayer film characterized by satisfy | filling. It is a method for producing a polarizing plate in which a retardation film having a liquid crystal retardation layer on a substrate film and a polarizer are laminated via an adhesive layer,
A protective film peeling step for peeling the protective film from the laminated film according to claim 1;
And a polarizer bonding step of bonding a polarizer on the retardation film via an adhesive. A retardation film having a liquid crystal retardation layer on a base film and a polarizer are laminated via an adhesive layer,
The polarizing plate, wherein the liquid crystal retardation layer has an arithmetic average roughness Wa of 70 nm or less on the surface opposite to the base film side. A retardation film having a liquid crystal retardation layer on a base film,
The retardation film, wherein the liquid crystal retardation layer has an arithmetic average waviness value Wa of 70 nm or less on the surface opposite to the base film side.

Images