KR20190104901A - Polarizing plate and method for prducing the same - Google Patents

Abstract

Even if a polarizing plate is provided with a retardation film, the purpose of this invention is to make the recognition of unevenness occurred on a surface of visibility of the polarizing plate difficult, so as to make the external appearance of a polarizing plate favorable. Through an adhesive layer, the polarizer and the retardation film are stacked, and when one-dimensional power spectrum with respect to the period f (micrometer) of surface unevenness is set to H^2 (f), the surface on the opposite side to the polarizer in the retardation film satisfies the following formula (1), H^2(425)/H^2 (212) =< 10, and the retardation film is a polarizing plate which is a film stacked on the image display element.

Description

POLARIZING PLATE AND METHOD FOR PRDUCING THE SAME

The present invention relates to a polarizing plate and a manufacturing method of the polarizing plate.

Liquid crystal display devices and organic electroluminescent (EL) display devices have low power consumption, operate at low voltage, are light and thin, and are used in various display devices. The liquid crystal panel which comprises a liquid crystal display device has a structure by which a pair of linear polarizing plates were laminated | stacked on both surfaces of a liquid crystal cell. As a linear polarizing plate, the thing of the structure which laminated | stacked the polarizer and a protective film through an adhesive agent is used normally. The organic EL display device has a circular polarizing plate disposed on the viewer side of the organic EL display element. As a circular polarizing plate, the thing of the structure which laminated | stacked the polarizer and retardation film through the adhesive bond layer is used normally.

With the development of a linear polarizing plate and a circular polarizing plate (hereinafter collectively referred to as a polarizing plate) to mobile devices, thinning of polarizers, protective films and the like constituting the polarizing plate is increasingly required. When the thickness of a polarizer, a protective film, etc. becomes thin, since an adhesive agent shrinks at the time of hardening | curing an adhesive agent or drying, the unevenness | corrugation which seems to wave to the surface of a protective film may be produced. Such unevenness leads to a problem in appearance when the polarizing plate is laminated on an image display element, that is, a liquid crystal cell or an organic EL display element, in particular, the surface uniformity of the viewer side surface is insufficient, and the luxury feeling is insufficient.

Patent Document 1 discloses a polarizing plate in which a protective film is laminated on a surface of a polarizer visually recognized through an adhesive layer. The polarizing plate of patent document 1 reduces the shrinkage force of an adhesive agent by making thickness of an adhesive bond layer relatively thin with respect to the total thickness of a polarizer and a protective film. By doing so, the unevenness | corrugation which arises in the visual recognition side surface of a protective film can be reduced, but there is much room for improvement.

In addition, when a polarizing plate has a retardation film, since unevenness | corrugation is emphasized and visually recognized more than physical surface unevenness, the defect of an external appearance is easy to be recognized.

Patent Document 1: Japanese Patent Application Laid-Open No. 2015-114538

Even if a polarizing plate is provided with a retardation film, this invention makes it difficult to visually recognize the unevenness | corrugation which arises in the visual recognition side surface of a polarizing plate, and makes it the objective of making the external appearance of a polarizing plate favorable.

[1] a polarizer and a retardation film are laminated through the adhesive layer,

When the one-dimensional power spectrum of the period f (㎛) of the surface irregularities with H ² (f), and to the surface of the opposite side and the polarizer in the above retardation film satisfy the formula (1),

The said retardation film is a polarizing plate which is a film laminated | stacked on the image display element side.

H ² (425) / H ² (212) ≤10 (1)

[2] The retardation film includes a liquid crystal layer having a thickness of 0.5 to 5.0 μm and a base film having a thickness of 10 to 50 μm, wherein the in-plane retardation value at a wavelength of 590 nm is 100 to 150 nm. The polarizing plate described.

[3] The polarizing plate according to [1] or [2], wherein the adhesive layer is a cured layer of an active energy ray-curable adhesive.

[4] a step of bonding a process paper on a retardation film to obtain a laminated film;

Peeling said process paper from said laminated film to obtain a retardation film;

Bonding a polarizer onto a retardation film via an adhesive to obtain a polarizing plate,

When the one-dimensional power spectrum of the period f (㎛) of the surface irregularities with H ² (f), the manufacturing method of the polarizing plate to to the bonded surface of the retardation film and in how the process satisfies the following formula (2) .

H ² (425) / H ² (212) ≤10 (2)

According to this invention, even when a polarizing plate is equipped with a retardation film, it becomes difficult to visually recognize the unevenness | corrugation which arises in the visual recognition side surface of a polarizing plate, and can make the external appearance of a polarizing plate favorable.

1 is a cross-sectional view showing an example of the polarizing plate of the present invention.
2 is a cross-sectional view showing an example of the polarizing plate of the present invention.

The polarizing plate of this invention and the manufacturing method of a polarizing plate are demonstrated suitably, referring drawings.

In one embodiment, the polarizing plate of this invention is equipped with the member shown in FIG. In the polarizing plate 100 shown in FIG. 1, the polarizer 2 and the retardation film 20 are laminated | stacked through the adhesive bond layer 10. As shown in FIG. In FIG. 1, the retardation film 20 includes a base film 3 and a liquid crystal layer 5.

The polarizing plate of this invention may contain the protective film, an adhesive layer, etc. further. In one embodiment, the polarizing plate of this invention is equipped with the member shown in FIG. In the polarizing plate 101 shown in FIG. 2, the retardation film 20 is laminated on one surface of the polarizer 2 via the adhesive layer 10, and the adhesive layer 11 is formed on the other surface of the polarizer 2. The protective film 4 is laminated | stacked through (), and the adhesive layer 6 is laminated | stacked on the retardation film 20. FIG. The adhesive layer 6 may be an adhesive layer for bonding to image display elements, such as a liquid crystal cell, for example.

In the polarizing plate of the present invention, when the one-dimensional power spectrum with respect to the period f (µm) of surface irregularities is H ² (f), the surface on the side opposite to the polarizer in the retardation film is expressed by the following formula (1): Satisfies. It is preferable that it is 6 or less, and, as for the left side of following formula (1), it is more preferable that it is four or less. The lower limit is not particularly limited, but may be two or more.

H ² (425) / H ² (212) ≤10 (1)

H ² 425 represents a one-dimensional power spectrum at a period of 425 μm, and H ² 212 represents a one-dimensional power spectrum at a period of 212 μm, and can be measured by the method described in Examples described later.

When surface unevenness | corrugation of a retardation film satisfy | fills said Formula (1), it can make it hard to visually recognize unevenness | corrugation which arises in the visual recognition side surface of a polarizing plate. The visual side surface of a polarizing plate is the surface of the polarizer 2 in the polarizing plate 100 shown in FIG. 1, for example, and is the surface of the protective film 4 in the polarizing plate 101 shown in FIG. That is, by making the surface shape of the retardation film arrange | positioned near the image display element closer to a polarizer based on Formula (1), it becomes difficult to visually recognize the unevenness | corrugation of the surface of the polarizing plate farther from an image display element, and to make a favorable appearance. can do.

Although the above formula (1) estimates how it contributes to making it hard to visually recognize the unevenness | corrugation of the visual recognition side surface, it does not limit this invention at all. The one-dimensional power spectrum of the period 212 micrometers or the period 425 micrometers in surface unevenness | corrugation has shown the magnitude | size of the waviness about 200 micrometers or about 400 micrometers of periods of the surface in retardation film, respectively. As mentioned later, in the manufacturing process, in the manufacturing process, process paper may bond together for the prevention of a wound and the blocking countermeasure of retardation films. As a result, the surface shape of the process paper may be transferred to the retardation film. The ease of transfer of the surface shape has been found to depend on the period of the surface shape. Specifically, it has been found by the inventor's examination that the surface shape having a period of about 400 μm is easy to be transferred, and that the surface shape having a period of 300 μm or less is difficult to be transferred. That is, simply reducing the physical unevenness of the retardation film surface by making the arithmetic mean wavy degree Wa or less predetermined is insufficient to make it difficult to visually recognize unevenness of the visual side. By making the magnitude | size of the wave shape about 400 micrometers periodical about the 200 micrometers periodical wave into a predetermined range, it is thought that the unevenness | corrugation of the visual recognition side surface can become difficult to recognize.

The surface on the opposite side to the polarizer of the retardation film satisfies the above formula (1). The arithmetic mean roughness Ra of this surface (JIS B 0601-2001) is usually 0 nm or more, preferably 10 nm or more, usually 1000 nm or less, preferably 500 nm or less, and Kurtosis Pku (JIS B 0601). -2001) is usually 0 or more, preferably 1.0 or more, usually 10 or less, preferably 5 or less, and the skewness Psk (JIS B 0601-2001) is usually -5 to +5, preferably -1 to + 1

Hereinafter, each member which comprises the polarizing plate of this invention is demonstrated.

(Polarizer)

The polarizer used for this invention is the process of uniaxially stretching a polyvinyl alcohol-type resin film, the process of adsorb | sucking a dichroic dye by dyeing a polyvinyl alcohol-type resin film with a dichroic dye, and the polyvinyl which the dichroic dye adsorbed. It is manufactured through the process of processing an alcoholic resin film with the boric-acid aqueous solution, and the process of washing with water after the process by the boric-acid aqueous solution.

As polyvinyl alcohol-type resin, what saponified polyvinyl acetate type resin can be used. As polyvinyl acetate type resin, the copolymer etc. with the other monomer copolymerizable with vinyl acetate besides the polyvinyl acetate which is a homopolymer of vinyl acetate are mentioned. As another monomer copolymerizable with vinyl acetate, unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, acrylamide which has an ammonium group, etc. are mentioned, for example.

Saponification degree of polyvinyl alcohol-type resin is about 85-100 mol% normally, and 98 mol% or more is preferable. The polyvinyl alcohol-based resin may be modified. For example, polyvinyl formal, polyvinyl acetal, or the like 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 polyvinyl alcohol-type resin into a film is used as a raw film of a polarizer. The method of forming a polyvinyl alcohol-type resin into a film can be formed into a well-known method. When considering the thickness of the polarizer obtained as 15 micrometers or less, the film thickness of a polyvinyl alcohol-type raw film is about 5-35 micrometers, and it is more preferable that it is 5-20 micrometers. When the film thickness of a raw film is 35 micrometers or more, it is necessary to raise the draw ratio at the time of manufacturing a polarizer, and there exists a tendency for the dimensional shrinkage of the polarizer obtained to become large. On the other hand, when the film thickness of a raw film is 5 micrometers or less, the handling property at the time of extending | stretching falls and it exists in the tendency for problems, such as a cutting | disconnection, to occur easily during manufacture.

Uniaxial stretching of a polyvinyl alcohol-type resin film can be performed before dyeing, simultaneously with or after dyeing of a dichroic dye. When performing uniaxial stretching after dyeing, this uniaxial stretching may be performed before or after boric acid treatment. In addition, you may uniaxially stretch in several of these steps.

In uniaxial stretching, you may extend uniaxially between the rolls from which a circumferential speed differs, and may extend uniaxially using a thermal roll. In addition, uniaxial stretching may be dry stretching which extends | stretches in air | atmosphere, and wet extending | stretching may be performed in the state which swelled the polyvinyl alcohol-type resin film using a solvent. A draw ratio is about 3 to 8 times normally.

As a method of dyeing a polyvinyl alcohol-type resin film with a dichroic dye, the method of immersing a polyvinyl alcohol-type resin film in the aqueous solution containing a dichroic dye is employ | adopted, for example. As a dichroic dye, an iodine or a dichroic dye is used specifically ,. Moreover, it is preferable that the polyvinyl alcohol-type resin film is immersed in water before a dyeing process.

When using iodine as a dichroic dye, the method of immersing and dyeing a polyvinyl alcohol-type resin film in the aqueous solution containing iodine and potassium iodide is employ | adopted normally. Content of iodine in this aqueous solution is about 0.01-1 weight part per 100 weight part of water normally. In addition, content of potassium iodide is about 0.5-20 weight part per 100 weight part of water normally. The temperature of the aqueous solution used for dyeing is about 20-40 degreeC normally. In addition, the immersion time (dyeing time) in this aqueous solution is about 20 to 1,800 second normally.

On the other hand, when using a dichroic dye as a dichroic dye, the method of immersing and dyeing a polyvinyl alcohol-type resin film in the aqueous solution containing water-soluble dichroic dye is employ | adopted normally. Content of the dichroic dye in this aqueous solution is about 1 * 10 <^-4> -10 weight part normally per 100 weight part of water, and about 1 * 10 <^{-3> -1} weight part is preferable. This aqueous solution may contain inorganic salts, such as sodium sulfate, as a dyeing adjuvant. The temperature of the dichroic dye aqueous solution used for dyeing is about 20-80 degreeC normally. In addition, the immersion time (dyeing time) in this aqueous solution is about 10 to 1,800 second normally.

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

The amount of boric acid in boric-acid containing aqueous solution is about 2-15 weight part normally per 100 weight part of water, and 5-12 weight part is preferable. When using iodine as a dichroic dye, it is preferable that this boric acid containing aqueous solution contains potassium iodide. The amount of potassium iodide in boric-acid containing aqueous solution is about 0.1-15 weight part per 100 weight part of water normally, and about 5-12 weight part is preferable. Immersion time in boric-acid containing aqueous solution is about 60-1,200 second normally, about 150-600 second is preferable, and about 200-400 second is more preferable. The temperature of the boric acid containing aqueous solution is 50 degreeC or more normally, 50-85 degreeC is preferable and 60-80 degreeC is more preferable.

The polyvinyl alcohol-based resin film after boric acid treatment is usually washed with water. A water washing process can be performed by immersing the polyvinyl alcohol-type resin film processed by boric acid in water, for example. The temperature of the water in a water washing process is about 5-40 degreeC normally. In addition, immersion time is about 1 to 120 second normally.

After water washing, a drying process is performed and a polarizer is obtained. The drying treatment can be performed using a hot air dryer or a far infrared heater. Drying process temperature is about 30-100 degreeC normally, and 50-80 degreeC is preferable. Drying treatment time is about 60 to 600 second normally, and 120 to 600 second is preferable.

By the drying treatment, the moisture content of the polarizer is reduced to the practical level. The moisture content is 5-20 weight% normally, and 8-15 weight% is preferable. If the moisture content is less than 5% by weight, the flexibility of the polarizer is lost, and the polarizer may be damaged or break after drying. Moreover, when moisture content exceeds 20 weight%, the thermal stability of a polarizer may be inferior.

In addition, you may perform extending | stretching, dyeing, a boric acid treatment, a water washing process, and a drying process of the polyvinyl alcohol-type resin film in a polarizer manufacturing process according to the method of Unexamined-Japanese-Patent No. 2012-159778, for example. In the method described in this document, a polyvinyl alcohol-based resin layer serving as a polarizer is formed by coating polyvinyl alcohol-based resin on a base film.

The effect of the present invention is remarkable when the thickness of the polarizer is thinner (not thin). For example, the thickness of the polarizer may be 15 µm or less, or 10 µm or less. From the viewpoint of making the optical characteristic good, the thickness of the polarizer is, for example, 3 µm or more.

(Protective film)

A protective film is comprised by a resin film and can also be comprised by a transparent resin film. In particular, it is preferable to comprise a material which is excellent in transparency, mechanical strength, thermal stability, moisture shielding property and the like. In this specification, a transparent resin film means the resin film whose monolithic transmittance is 80% or more in visible region.

Although it does not specifically limit as resin which forms a protective film, 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, poly And films made of butylene terephthalate resin, polyethylene terephthalate resin, polysulfone resin, polyether sulfone resin, polyarylate resin, polyamideimide resin, polyimide resin and the like. These resin films can be a film formed by raw material resin, a uniaxial stretched film obtained by transverse stretching after film formation, a biaxially stretched film obtained by longitudinal stretching after film formation, and then transverse stretching.

These resin can be used individually or in combination of 2 or more types. In addition, these resins may be used after performing any appropriate polymer modification, and the polymer modification may include, for example, copolymerization, crosslinking, molecular terminal modification, stereoregularity control, and mixing involving cases involving heterogeneous polymers. And other modifications.

Among these, it is preferable to use methyl methacrylate resin, polyethylene terephthalate resin, polyolefin resin, or cellulose resin as a material of a protective film. Polyolefin resin here contains chain | strand polyolefin resin and cyclic polyolefin resin.

The film used as a protective film can obtain a commercial item easily, and if it is a methyl methacrylate type resin film, it is Sumipex (manufactured by Sumitomo Chemical Co., Ltd.), Acrilite (registered trademark) in the brand name, respectively. , Acriprene (registered trademark) (above, Mitsubishi Rayon Co., Ltd.), Deraglas (registered trademark) (made by Asahi Kasei Co., Ltd.), Paraglass (registered trademark), Como glass (registered trademark) ( The foregoing is manufactured by Kabushiki Kaisha Kureray, Akryua (registered trademark) (manufactured by KK Corporation). If it is a polyolefin resin film, Zeono (registered trademark) (Nippon Xeon Co., Ltd.), Aton (registered trademark) (JSR Corporation) etc. are mentioned as a brand name, respectively. If it is a polyethylene terephthalate type resin film, Novaklea (trademark) (made by Mitsubishi Chemical Corporation) and Teijin A-PET sheet (made by Teijin Chemical Co., Ltd.) etc. are mentioned as a brand name, respectively. . If it is a polypropylene resin film, it is a FILMAX CPP film (made by FILMAX Corporation), Santox (trademark) (made by Santox Corporation), Tocelo (trademark) (made by Tocelo Corporation) under a brand name, respectively. , Toyobopyrene Film (registered trademark) (manufactured by Toyobo Co., Ltd.), Torrepan (registered trademark) (manufactured by Toray Film Co., Ltd.), Nippon Polyace (manufactured by Nippon Polyace Co., Ltd.), and Daikoku (trademark) FC (made by Futamura Kagaku Co., Ltd.), etc. are mentioned. Moreover, in the case of a cellulose resin film, FujiTak (trademark) TD (made by Fujifilm Co., Ltd.), KC2UA, and Konica Minolta TAC film KC (made by Konica Minolta Co., Ltd.) etc. are mentioned as a brand name, respectively.

In addition, a protective film may 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 resistant agent, an impact modifier, and the like.

The effect of the present invention is remarkable when the thickness of the protective film is thinner (not thin). For example, the thickness of the protective film may be 1 to 50 µm, 10 to 40 µm, or 10 to 35 µm. .

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

(Retardation film)

Retardation film can be formed, for example with resin illustrated as a material of the said protective film, Especially, cyclic olefin resin and styrene resin are preferable. The retardation film may be formed in a single layer or may be formed in a plurality of layers. The retardation film having a plurality of layers includes, for example, a resin film (base film) exemplified as the material of the protective film and a liquid crystal layer polymerized with a liquid crystal compound, and a plurality of (for example, two layers) liquid crystal layers. Also good. The layer having a phase difference may be a resin film and / or a liquid crystal layer.

When in-plane retardation value in wavelength (lambda) (nm) is set to Re ((lambda)), and the retardation value of thickness direction is set to Rth ((lambda)), In one Embodiment, in-plane retardation value Re (590) of a retardation film is For example, it can be 100-150 nm, and the phase difference value Rth (590) of thickness direction can be -200- + 200 nm, for example.

The in-plane retardation value Re and the thickness direction retardation value Rth are nx for the refractive index in the in-plane slow axis direction, ny for the refractive index in the in-plane fast axis direction (the direction orthogonal to the in-plane slow axis direction), and the refractive index in the thickness direction nz, for the retardation film. When thickness is d, it is defined by following formula (3) and formula (4).

   Re = (nx-ny) × d (3)

   Rth = [{(nx + ny) / 2} -nz] × d (4)

The liquid crystal layer included in the retardation layer may be a λ / 4 plate, a λ / 2 plate, or a positive C layer. When the retardation layer includes a plurality of liquid crystal layers, a combination of a quarter wave plate and a half wave plate and a combination of a quarter wave plate and a positive C plate are preferable. The λ / 4 plate is a layer in which the in-plane retardation value Re (550) at the wavelength of 550 nm satisfies the relationship of 100 nm ≤ Re (550) ≤ 200 nm. The λ / 4 plate may exhibit reverse wavelength dispersion that satisfies Re (450) <Re (550) <Re (650). The λ / 2 plate is a layer in which Re (550) satisfies 210 nm ≦ Re (550) ≦ 300 nm. The positive C layer satisfies the relationship of nz> nx ≧ ny (the difference between the magnitude of nx and the magnitude of ny is within ± 1%, for example), and the phase difference value Rth in the thickness direction at the wavelength lambda [nm] ( λ) preferably satisfies the relationship of -300 nm ≤ Rth (550) ≤ -20 nm.

When a retardation layer contains a liquid crystal layer, compared with the case where a retardation layer is comprised only by a resin film, the defect of an external appearance is easy to be recognized. It is because a liquid crystal layer is thin compared with a resin film, and the change of phase difference per unit thickness becomes large.

The liquid crystal layer contained in the retardation layer is a layer including a layer in which a liquid crystal compound is polymerized and cured. Although it does not specifically limit about the kind of liquid crystal compound, According to the shape, it can classify into a rod type (bar type | mold liquid crystal compound) and a disk type (disk type liquid crystal compound, a discotic liquid crystal compound). In addition, there are low molecular type and high polymer type, respectively. Herein, the polymer generally refers to a polymer having a degree of polymerization of 100 or more (polymer physics and phase change dynamics, Toi Masao, page 2, Iwanami Shoten, 1992). In this embodiment, any liquid crystal compound can be used. Moreover, you may use 2 or more types of rod-shaped liquid crystal compounds, 2 or more types of disk-shaped liquid crystal compounds, or a mixture of a rod-shaped liquid crystal compound and a disk-shaped liquid crystal compound.

As the rod-shaped liquid crystal compound, for example, those described in claims 1 of JP-A-11-513019 or paragraphs [0026] to [0098] of JP-A-2005-289980 can be suitably used. As a disc shaped liquid crystal compound, the thing of Paragraph [0020]-[0067] of Unexamined-Japanese-Patent No. 2007-108732, or Paragraph [0013]-[0108] of Unexamined-Japanese-Patent No. 2010-244038 can be used suitably, for example.

As for a liquid crystal layer, it is more preferable to form using the liquid crystal compound (rod type liquid crystal compound or disk shaped liquid crystal compound) which has a polymeric group. Thereby, the temperature change and the humidity change of an optical characteristic can be made small.

The liquid crystal compound may be a mixture of two or more kinds. In that case, it is preferable that at least one has two or more polymerizable groups. That is, it is preferable that a liquid crystal layer is a layer in which the rod-shaped liquid crystal compound which has a polymeric group, or the disc shaped liquid crystal compound which has a polymeric group was fixed by superposition | polymerization and formed. In this case, after forming the layer, it is no longer necessary to show liquid crystallinity.

The kind of the polymerizable group contained in the rod-shaped liquid crystal compound or the disk-shaped liquid crystal compound is not particularly limited, and for example, a functional group capable of addition polymerization reaction such as a polymerizable ethylenically unsaturated group or a ring polymerizable group is preferable. More specifically, a (meth) acryloyl group, a vinyl group, a styryl group, an allyl group, etc. are mentioned, for example. Especially, a (meth) acryloyl group is preferable. Here, (meth) acryloyl group is a concept containing both a methacryloyl group and acryloyl group.

The formation method of a liquid crystal layer is not specifically limited, A well-known method is mentioned. For example, the composition for optically anisotropic layer formation (henceforth simply called "composition") containing the liquid crystal compound which has a polymeric group is apply | coated to a resin film (base film), a coating film is formed, and the hardening process with respect to the obtained coating film Retardation layer can be manufactured by performing (irradiation of ultraviolet rays (light irradiation process) or heat processing). The manufactured retardation layer can be transferred to a polarizer phase, a protective film phase, or another resin film (base film), for example.

Application of the composition can be carried out 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 liquid crystal compound mentioned above. 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 polymerization reaction. For example, as a photoinitiator, the (alpha)-carbonyl compound, the acyloin ether, the (alpha) -hydrocarbon substituted aromatic acyloin compound, a polynuclear quinone compound, the combination of a triarylimidazole dimer, and p-aminophenyl ketone, etc. are mentioned. . It is preferable that it is 0.01-20 mass% with respect to the total solid of a composition, and, as for the usage-amount of a polymerization initiator, it is more preferable that it is 0.5-5 mass%.

In addition, a polymerizable monomer may be contained in the composition from the point of uniformity and film strength of a coating film. A radically polymerizable or cationically polymerizable compound is mentioned as a polymerizable monomer. Especially, a polyfunctional radically polymerizable monomer is preferable.

Moreover, as a polymerizable monomer, it is preferable that it is copolymerizable with the liquid crystal compound containing the polymerizable group mentioned above. As a specific polymerizable monomer, the thing of Paragraph [0018]-[0020] of Unexamined-Japanese-Patent No. 2002-296423 is mentioned, for example. It is preferable that it is 1-50 mass% with respect to the total mass of a liquid crystal compound, and, as for the usage-amount of a polymeric monomer, it is more preferable that it is 2-30 mass%.

Moreover, surfactant may be contained in a composition from the point of uniformity and film strength of a coating film. As surfactant, a conventionally well-known compound is mentioned. Especially, a fluorine compound is preferable.

In addition, the composition may contain a solvent, and an organic solvent is used preferably. Examples of the organic solvent include amide (e.g., N, N-dimethylformamide), sulfoxide (e.g., dimethyl sulfoxide), heterocyclic compound (e.g. pyridine), hydrocarbon (e.g., benzene, hexane), alkyl halide (e.g. Chloroform, dichloromethane), esters (e.g. methyl acetate, ethyl acetate, butyl acetate), ketones (e.g. acetone, methyl ethyl ketone), ethers (e.g. tetrahydrofuran, 1,2-dimethoxyethane) Can be. Especially, alkyl halide and ketone are preferable. Moreover, you may use together 2 or more types of organic solvents.

Moreover, in a composition, various orientations, such as the vertical alignment promoter, such as the vertical alignment agent of the polarizer interface side, the vertical alignment agent of the air interface side, and the horizontal alignment accelerator, such as the horizontal alignment agent of the polarizer interface side, and the horizontal alignment agent of the air interface side, etc. I may be included. In addition to the above components, the composition may further include an adhesion improving agent, a plasticizer, a polymer, and the like.

The alignment film which has a function which defines the orientation direction of a liquid crystal compound may be contained in the liquid crystal layer. An alignment film generally has a polymer as a main component. As a polymeric material for an oriented film, many documents have description and it can obtain many commercial products.

In addition, a well-known orientation treatment is given to an orientation film normally. Although a rubbing process, the photo-alignment process to apply polarization, etc. are mentioned, Photo-alignment process is preferable from a viewpoint of the arithmetic mean waveform degree of an oriented film.

The effect of the present invention is remarkable when the thickness of the retardation film is thinner (when not applied), and the thickness of the retardation film may be, for example, 60 µm or less, or 40 µm or less. The thickness of retardation film is 5 micrometers or more normally. Moreover, when a retardation film contains a base film and a liquid crystal layer, it is preferable that the thickness of a base film is 10-50 micrometers, It is more preferable that it is 10-30 micrometers, It is preferable that the thickness of a liquid crystal layer is 0.5-5.0 micrometers desirable.

In addition, the elasticity modulus of a retardation film may be 5000 Mpa or less in 23 degreeC, 3000 Mpa or less may be sufficient, and is 2000 Mpa or more normally. Elastic modulus can be measured based on JISK7116. When there is anisotropy in elasticity modulus in MD direction and a TD direction, in this specification, an elasticity modulus can be made into the average of both.

Even in the retardation film which has the thickness and elastic modulus of such a range, according to this invention, it can make it hard to visually recognize the unevenness | corrugation of the visual recognition side surface by satisfying Formula (1).

Moreover, from a viewpoint of making the external appearance of a polarizing plate more favorable, it is preferable that an arithmetic mean wave shape (Wa) is 50 nm or less, and, as for the surface on the opposite side to the polarizer side in retardation film, it is more preferable that it is 40 nm or less. It is more preferable that it is 30 nm or less. The arithmetic mean wave shape Wa of the surface on the opposite side to the polarizer side in retardation film is 10 nm or more normally.

(Adhesive layer)

As an adhesive agent which forms an adhesive bond layer, an active energy ray hardening-type adhesive agent or an aqueous adhesive agent can be used. That is, an adhesive bond layer is a hardened layer of an adhesive agent.

As mentioned above, as one of the factors which generate | occur | produces unevenness | corrugation on the surface of a polarizing plate, the hardening shrinkage at the time of hardening or drying of an adhesive agent is mentioned. The shrinkage force (per unit time) in the case of using an active energy ray-curable adhesive that cures the adhesive in a short time by light irradiation and performs the adhesion is generally determined by drying of the solvent (for example, water) by heating and then curing as necessary. It is larger than the water-based adhesive agent which adhere | attaches by comparatively time by this. Therefore, in this invention, when the adhesive bond layer for laminating retardation film is formed with an active energy ray hardening-type adhesive agent, it can apply especially suitably, and the uneven | corrugated suppression effect obtained is high.

In the case where the protective film and the retardation film are disposed on both sides of the polarizer as in the polarizing plate 101 shown in FIG. 2, the adhesive for laminating the protective film and the adhesive for laminating the retardation film may be the same or different from each other. You may. It is preferable that the adhesive agent for laminating a protective film and the adhesive agent which forms an adhesive bond layer are active energy ray hardening-type adhesive agents for the same reason as mentioned above.

The active energy ray-curable adhesive means an adhesive which is cured by irradiating active energy rays such as electron beams and ultraviolet rays, and includes, for example, a polymerizable compound and a photopolymerization initiator, a photoreactive resin, a binder resin and a photoreactive agent. The thing containing a crosslinking agent, etc. are mentioned. As a polymeric compound, Photocurable epoxy-type compound; Photocurable vinyl compounds such as a photocurable acrylic compound; A photocurable urethane type compound can be mentioned. As a photoinitiator, a photocationic polymerization initiator (for example, when using a photocurable epoxy type compound), and a photoradical polymerization initiator (for example, when using a photocurable acrylic compound) are mentioned.

As an aqueous adhesive agent, the adhesive agent which consists of polyvinyl alcohol-type resin aqueous solution, an aqueous two-component urethane emulsion adhesive, etc. are mentioned. Especially, the aqueous adhesive which consists of aqueous solution of polyvinyl alcohol-type resin is used suitably.

As polyvinyl alcohol-type resin, in addition to the vinyl alcohol homopolymer obtained by saponifying polyvinyl acetate which is a homopolymer of vinyl acetate, the polyvinyl alcohol-type air obtained by saponifying the copolymer of vinyl acetate and the other monomer copolymerizable with this. The modified polyvinyl alcohol polymer etc. which partially modified | polymerized or these hydroxyl groups can be used. The aqueous adhesive may include additives such as polyhydric aldehyde, water-soluble epoxy compound, melamine-based compound, zirconia compound, zinc compound and the like.

The thickness of the adhesive layer is, for example, 5 µm or less, preferably 2 µm or less, and may be 1 µm or less from the viewpoint of reducing the shrinkage during curing or drying of the adhesive to further reduce the unevenness of the polarizing plate. In addition, from a viewpoint of expressing sufficient adhesive force, the thickness of an adhesive bond layer is normally 0.01 micrometer or more.

The said adhesive may contain the additive. As an additive, an ion trap agent, antioxidant, a chain transfer agent, a sensitizer, a tackifier, a thermoplastic resin, a filler, a flow regulator, a plasticizer, an antifoamer, etc. are mentioned.

(Adhesive layer)

An adhesive layer can be laminated | stacked on the surface of a polarizing plate. A polarizing plate can be bonded to image display elements, such as a liquid crystal cell, through this adhesive layer. In FIG. 2, the adhesive layer 6 corresponds to this. It is preferable that the thickness of the adhesive layer formed from an adhesive is 5-25 micrometers. More preferably, it is 10-25 micrometers.

As an adhesive which forms an adhesive layer, an acrylic polymer, a silicone type polymer, polyester, a polyurethane, a polyamide, a polyvinyl ether, a vinyl acetate / vinyl chloride copolymer, a modified polyolefin, an epoxy type, a fluorine type, natural rubber, synthetic rubber etc. It can select suitably and use polymers, such as a rubber type | system | group, as a base polymer. As the pressure-sensitive adhesive, one that is particularly excellent in optical transparency, exhibits proper wettability, cohesiveness, and adhesive adhesion characteristics, and is excellent in season resistance, heat resistance, and the like is preferable.

In addition, various additives may be mix | blended with an adhesive. Examples of the additive include a silane coupling agent and an antistatic agent.

Hereinafter, the manufacturing method of the polarizing plate of this invention is demonstrated. The polarizing plate of this invention can be manufactured by the method containing the following processes, for example.

Process (1): After forming an orientation film on a base film, the process of forming a liquid crystal layer by apply | coating and polymerizing a liquid crystal compound on this orientation film, and obtaining a retardation film.

Process (2): The process of bonding a process paper on retardation film, and obtaining a laminated film.

Process (3): The process of peeling a process sheet from a laminated film and obtaining a retardation film.

Process (4): The process of bonding a polarizer (or polarizer which has a protective film) on retardation film via an adhesive agent, and obtaining a polarizing plate.

(Step (1))

Process (1) is a process of manufacturing retardation film. When a base film and a liquid crystal layer are included as retardation film, as above-mentioned, the alignment film for orientating a liquid crystal compound is first formed on a base film. Examples of the alignment film include an alignment film containing an alignment polymer, a photoalignment film, and a groove alignment film in which an uneven pattern or a plurality of grooves are formed and oriented on the surface thereof, and can be formed by a conventionally known method.

Next, after apply | coating the composition containing a liquid crystal compound on an oriented film, and drying a solvent as needed, a liquid crystal compound is polymerized. The polymerization of the liquid crystal compound can be performed by a known method for polymerizing a compound having a polymerizable functional group. Specifically, thermal polymerization and photopolymerization are mentioned, and photopolymerization is preferable from the viewpoint of the ease of polymerization. Photopolymerization can be performed by irradiating an active energy ray, such as an ultraviolet-ray, to a liquid crystal compound. The active energy ray may be irradiated from the base film side, may be irradiated from the liquid crystal compound side, or may be irradiated from both the base film side and the liquid crystal compound side.

(Step (2))

Process (2) is a process of laminating | stacking process paper on retardation film, and obtaining a laminated film. By laminating | stacking a process paper on retardation film, handling at the time of preservation and transport of retardation film can be made easy, blocking of retardation films can be prevented, or dust etc. adhere to retardation film, and it can be prevented from becoming a defect. From such a viewpoint, the process sheet is preferably laminated on the liquid crystal layer in the retardation film.

The process paper in the step (2) may be formed in a single layer or may be formed in a plurality of layers. Although the adhesive layer may be included and it is not necessary to have an adhesive layer, the process paper which has a self-adhesive layer is preferable at the point that defects, such as debris, can be reduced. As a material which forms a process paper, resin similar to the material which forms the said protective film is mentioned, Especially, polyolefin resin and polyethylene terephthalate type resin are preferable.

As a process paper, what can be obtained as a commercial item can be used. As an example of a commercial item which has a base film of polyethylene terephthalate type resin, "Cosmoshine (registered trademark) A4100" by Toyobo Co., Ltd. is mentioned. Examples of commercially available products having a base film of polyethylene-based resin include "Force Field (registered trademark) 1035" manufactured by Tredegar Film Products Corporation and "Toretech (registered trademark)" manufactured by Toray Film Co., Ltd ..

In order to achieve the surface shape which satisfy | fills said Formula (1), especially the surface shape of the process paper used at a process (2) is important, The surface where the retardation film in a process paper is laminated | stacked is the period f (micrometer) of surface asperity It is preferable to satisfy the following formula (2) when the one-dimensional power spectrum with respect to) is set to H ² (f). A power spectrum can be measured by the method as described in the Example mentioned later. The lower limit of the H ² (425) / H ² 212 is not particularly limited, but may be two or more.

H ² (425) / H ² (212) ≤10 (2)

The arithmetic mean roughness Ra of the process paper surface (JIS B 0601-2001) is usually 0 nm or more, preferably 10 nm or more, usually 500 nm or less, preferably 200 nm or less, and the Kurtosis Pku (JIS B 0601-2001) is usually 0 or more, preferably 1.0 or more, usually 10 or less, preferably 5 or less, and the skewness Psk (JIS B 0601-2001) is usually -5 to +5, preferably -1 to +1.

By laminating | stacking such surface-form process paper on retardation film, the desired surface shape which satisfy | fills Formula (1) can be transferred to retardation film, and the external appearance of the visual recognition side surface of a polarizing plate can be made favorable.

When the said commercially available film is used as a process paper, since the surface shape may differ for every grade and a lot, the film which satisfy | fills Formula (2) is selected suitably, and it uses. Moreover, what is necessary is just to make the surface which satisfy | fills Formula (2) into the surface on which retardation film is laminated | stacked, when surface shape differs from one surface of a process paper and the other surface.

In addition, from the viewpoint of making the appearance of the polarizing plate better, the surface on which the phase difference film in the process paper is laminated is preferably 200 nm or less, more preferably 150 nm or less, more preferably 100 nm The following may be sufficient. The arithmetic mean wave shape Wa of the surface where retardation film in a process paper is laminated | stacked is 50 nm or more normally.

(Step (3))

Process (3) is a process of peeling a process sheet from a laminated film and obtaining a retardation film. Although a peeling method is not specifically limited, For example, you may peel, making process paper or a retardation film wound on a roll. In addition, you may wind up the process paper which peeled.

(Step (4))

Process (4) is a process of bonding a polarizer (or polarizer which has a protective film) on a retardation film via an adhesive agent, and obtaining a polarizing plate. An adhesive may be apply | coated to retardation film, may be apply | coated to a polarizer, and may be apply | coated to both retardation film and a polarizer. In addition, when a retardation film contains a liquid crystal layer and a resin film, the bonding surface to a polarizer may be the surface of a resin film, or the surface of a liquid crystal layer may be sufficient as it. When an aqueous adhesive is used as the adhesive, the retardation film and the polarizer can be adhered by drying. When an active energy ray hardening-type adhesive agent is used as an adhesive agent, a retardation film and a polarizer can be adhere | attached by irradiating active energy rays, such as an ultraviolet-ray.

When using an aqueous adhesive agent, drying can be performed, for example by introducing the film after bonding into a drying furnace. Preferably drying temperature (temperature of drying furnace) is 30-90 degreeC. If it is less than 30 degreeC, there exists a tendency for retardation film and a protective film to peel easily from a polarizer. Moreover, when a drying temperature exceeds 90 degreeC, there exists a possibility that the polarization performance of a polarizer may deteriorate by heat. Drying time can be made into about 10 to 1000 second.

After a drying process, you may provide the curing process which cures for about 12 to 600 hours at room temperature or temperature slightly higher, for example, about 20-45 degreeC. 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.

Although the irradiation intensity of the active energy ray to an active energy ray hardening-type adhesive agent is suitably determined by the composition of an active energy ray hardening-type adhesive agent, it is set so that the irradiation intensity of the wavelength range effective for activation of a polymerization initiator may be 0.1-6000 mW / cm <2>. It is preferable. When the irradiation intensity is 0.1 mW / cm 2 or more, the reaction time does not become too long, and when 6000 mW / cm 2 or less, the yellowing of the active energy ray-curable adhesive due to heat radiated from the source and the heat generated during curing of the active energy ray-curable adhesive And less likely to cause deterioration of the polarizer.

The irradiation time to the active energy ray-curable adhesive is also appropriately determined by the composition of the active energy ray-curable adhesive, but is set so that the accumulated light amount expressed as the product of the irradiation intensity and the irradiation time is 10 to 10000 mJ / cm 2. It is preferable to be. When the accumulated light amount 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 does not become too long, so that good productivity is achieved. I can keep it.

In bonding a polarizer on a retardation film, in order to improve adhesiveness with a polarizer, surface treatments, such as a plasma process, a corona treatment, an ultraviolet irradiation process, a flame (flame) process, and a saponification process, are carried out on the retardation film surface. Processing) can be performed. For example, when a retardation film contains cyclic polyolefin type resin, it is preferable to perform a plasma process or a corona treatment. Moreover, when a retardation film consists of cellulose ester-type resin, it is preferable to perform a saponification process. As a saponification process, the method of immersing in aqueous alkali solution, such as sodium hydroxide and potassium hydroxide, is mentioned.

In process (4), the polarizer which has a protective film can be bonded to retardation film, and a polarizing plate can also be obtained. A protective film may be laminated | stacked previously on an polarizer through an adhesive agent, the polarizer which has a protective film may be manufactured, and the polarizer and retardation film in the polarizer which has a protective film may then be bonded together. As a method of bonding a protective film and a polarizer, the same method as the method of bonding the said retardation film and a polarizer is mentioned. In addition, a protective film, a polarizer, and three retardation films may be bonded together at the same time to obtain a polarizing plate.

Although the example which bonded the retardation film and a polarizer after peeling a process paper was shown in the above example, you may peel a process paper, after bonding a retardation film and a polarizer of course. That is, the order of process (3) and process (4) is arbitrary.

Although a polarizing plate can be manufactured as mentioned above, you may form an adhesive layer on retardation film further. This adhesive layer may be an adhesive layer for laminating | stacking on image display elements, such as a liquid crystal cell, for example. The pressure-sensitive adhesive layer may be formed by directly applying the pressure-sensitive adhesive on the retardation film, or may be formed by coating the pressure-sensitive adhesive on the base film in advance to form the pressure-sensitive adhesive layer and then transferring the phase on the retardation film.

Moreover, when manufacturing a elongate polarizing plate continuously, you may cut | disconnect to predetermined shape (for example, a rectangle), and may be used as the sheet | leaf body of a polarizing plate.

The image display apparatus can be obtained by laminating | stacking the polarizing plate of this invention on an image display element. As an image display element, a liquid crystal cell, an organic EL display element, etc. are mentioned.

EXAMPLE

Hereinafter, although an Example demonstrates this invention further in detail, this invention is not defined by these examples. In the examples,% and parts indicating content to the amount of use are based on weight unless otherwise specified. In addition, the evaluation method used in the Example is as follows.

(1) thickness:

It measured using the digital micrometer MH-15M by Corporation | KK Corporation.

(2) In-plane retardation Re and thickness direction retardation Rth:

It measured with the light of wavelength 590nm at 23 degreeC using the retarder which made the principle of the parallel Nicole rotation method, KOBRA-WPR by Ojikisokuki Co., Ltd. make.

(3) One-dimensional power spectrum with respect to the period f (µm) of the retardation film surface and the process paper surface: H ² (f)

Surface irregularities were scanned using PLμNEO (manufactured by Sensowave Japan) which is a confocal interference microscope. By analyzing the data of the resulting unevenness it was calculated for H ² (212), and H ² (425) in the period 212 and period 425 ㎛ ㎛.

(4) Arithmetic Mean Wavelength: Wa

Arithmetic mean wave shape (Wa) was measured using VS1000 (manufactured by Hitachi High Tech Co., Ltd.) which is a scanning white interference microscope. The measurement range was made into X = 4000 micrometers or more and Y = 2000 micrometers or more, and the cutoff value was 100 micrometers.

(5) Appearance evaluation of the polarizing plate

The adhesive layer was laminated | stacked on the phase difference film of a polarizing plate, and the polarizing plate was bonded to the glass plate through the adhesive layer. The fluorescent lamp was shined on the polarizing plate, the reflecting image was observed, and external appearance was evaluated. The case where the outline of the fluorescent lamp was clearly observed without distortion was judged as good, and the case where the distortion of the outline of the fluorescent lamp was generated and cannot be clearly observed was judged as defective.

(6) Surface roughness Ra, Kurtosis Pku, and skewness Psk were calculated | required according to JIS B 0601-2001 from the data of the unevenness | corrugation obtained by the measurement of one-dimensional power spectrum, respectively.

Each member below was prepared.

(Polarizer)

(1) primer layer forming process

Polyvinyl alcohol powder ("Z-200" manufactured by Nippon Kosei Chemical Co., Ltd., average polymerization degree 1100, saponification degree 99.5 mol%) is dissolved in 95 degreeC hot water, and the polyvinyl alcohol aqueous solution of 3 weight% of concentration is carried out. Prepared. The crosslinking agent ("Sumirez resin 650" by Taoka Chemical Co., Ltd.) was mixed with the obtained aqueous solution at the ratio of 5 weight part with respect to 6 weight part of polyvinyl alcohol powders, and the coating liquid for primer layer formation was obtained.

An unstretched polypropylene (PP) film (melting point: 163 ° C.) having a thickness of 90 μm was prepared as a base film, corona treated on one side thereof, and then the primer layer was used on the corona treated side using a small diameter gravure coater. A coating layer for forming was coated and dried at 80 ° C. for 10 minutes to form a primer layer having a thickness of 0.2 μm.

(2) Preparation of laminated film (resin layer forming step)

Polyvinyl alcohol powder ("PVA124", the average degree of polymerization 2400, saponification degree 98.0-99.9 mol%) manufactured by KKK, was melt | dissolved in 95 degreeC hot water, the polyvinyl alcohol aqueous solution of 8 weight% of concentration was prepared, This was used as the coating liquid for polyvinyl alcohol-type resin layer formation.

After coating the coating liquid for polyvinyl alcohol-type resin layer formation with the lip coater on the surface of the primer layer of the base film which has the primer layer produced by said (1), it dried at 80 degreeC for 20 minutes, The polyvinyl alcohol-type resin layer was formed in it, and the laminated | multilayer film which consists of a base film / primer layer / polyvinyl alcohol-type resin layer was obtained.

(3) Preparation (stretching process) of stretched film

About the laminated | multilayer film produced in said (2), 5.8 times free end uniaxial stretching was performed at 160 degreeC using the floating longitudinal uniaxial stretching apparatus, and the stretched film was obtained. The thickness of the polyvinyl alcohol-type resin layer after extending | stretching was 6.1 micrometers.

(4) Preparation of the polarizing laminated film (dyeing step)

The stretched film produced in the above (3) was immersed in a dyeing solution at 30 ° C. containing iodine and potassium iodide (containing 0.6 parts by weight of iodine and 10 parts by weight of potassium iodide per 100 parts by weight of water) for about 180 seconds. After performing the dyeing process of the polyvinyl alcohol-type resin layer, the excess dye aqueous solution was wash | cleaned with 10 degreeC pure water.

Submerged in a first crosslinked aqueous solution at 78 ° C. containing boric acid (containing 9.5 parts by weight of boric acid per 100 parts by weight of water) for 120 seconds, followed by a second crosslinked aqueous solution at 70 ° C. containing boric acid and potassium iodide (water 100 9.5 parts by weight of boric acid and 4 parts by weight of potassium iodide per part by weight) was immersed for 60 seconds to perform a crosslinking treatment. Then, it washed with 10 degreeC pure water for 10 second, and finally dried at 40 degreeC for 300 second, and obtained the polarizing laminated film which consists of a base film / primer layer / polarizer.

(Protective film)

The film which provided the hard-coat layer on one surface of the cyclic olefin resin film (The Nippon Zeon Co., Ltd. make, the Zenoa film (trademark)) was prepared. The thickness was 50 μm.

(Process paper)

The following process papers were prepared. They are all process papers containing polyethylene-type resin and have a self-adhesive layer in a surface layer.

Process land A: Torredegas Corporation `` Force Field 1035 ''

Process sheet B: Toray Film Co., Ltd. product "Toretech (registered trademark) 7332K"

Process sheet C: Toray Film Co., Ltd. product "Toretec (registered trademark) N711"

Process sheet D: Torredegas Corporation "Pearl"

The arithmetic mean wave shape Wa on one surface of process paper A was 130 nm, H ² 425 was 160, and H ² 212 was 54. H ² (425) / H ² (212) on this surface was 3.0. In addition, the surface of this process paper A was visually smooth.

The arithmetic mean wave shape Wa on one surface of the process paper B was 140 nm, H ² 425 was 2700, and H ² 212 was 41. H ² (425) / H ² (212) on this surface was 66. In addition, the surface of this process sheet B was visually smooth.

H ² 425 on one surface of the process paper C is 2.71 × 10 ⁻⁵ , H ² 212 is 2.69 × 10 ⁻⁵ , and the surface roughness Ra is 190 nm and Kurtosis Pku Was 2.51 and the skewness Psk was -0.002. H ² 425 / H ² 212 of this surface is 1.01. In addition, the surface of this process paper C was visually smooth.

H ² 425 on one surface of the process paper D is 2.87 × 10 ⁻⁶ , H ² 212 is 1.24 × 10 ⁻⁶ , the surface roughness Ra is 98 nm, and the Kurtosis Pku Was 2.47, and the skewness Psk was -0.114. H ² 425 / H ² 212 of this surface is 2.31. In addition, the surface of this process paper C was visually smooth.

(Retardation film)

Nippon Xeon Co., Ltd. cyclic olefin resin film was prepared. The thickness was 20 μm. Corona treatment was given to one side of this film. The surface for corona treatment was coated with the composition for vertical alignment films so that a film thickness might be set to 1 micrometer. The coating film was subjected to heat treatment at a temperature of 100 ° C. for 120 seconds to form an alignment film. Nissan Kagaku Kogyo Co., Ltd. product Saneva SE610 was used for the composition for vertical alignment films.

On the alignment film formed above, the composition containing the prepared photopolymerizable nematic liquid crystal compound (made by Merck, RMM28B) was apply | coated. The composition contains propylene glycol monomethyl ether acetate (PGMEA) as a solvent and Irgacua (Irg-907) as a photoinitiator. The composition of this composition is as follows.

Photopolymerizable nematic liquid crystal compound [RMM28B]: 20 parts by weight

Photoinitiator [Irgacure (Irg-907)]: 5 parts by weight

Solvent [propylene glycol monomethyl ether acetate]: 80 parts by weight

The coating layer after coating was subjected to drying treatment 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 phase difference layer on which a liquid crystal compound having a thickness of 1 μm was cured (the thickness of the entire liquid crystal phase difference layer was 2 μm). Thus, the retardation film which consists of a base film and a liquid crystal retardation layer was obtained. The elasticity modulus of the retardation film was 1900 MPa, 2300 MPa in MD direction and TD direction, respectively at 23 degreeC.

Subsequently, said prepared process paper A-process paper D are bonded together on the liquid crystal layer so that the surface (the said one surface) which has the surface shape shown in Table 1 may become a bonding surface with a liquid crystal layer, respectively, and has process paper A A retardation film, a retardation film with process paper B, a retardation film with process paper C, and a retardation film with process paper D were obtained.

This retardation film can function as a (lambda) / 4 wavelength plate in the wavelength range of visible light, and showed the phase difference also in the thickness direction.

(Ultraviolet curable adhesive)

The ultraviolet curable adhesive which consists of the following compositions was prepared.

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 Co., Ltd.): 20 parts by weight,

2-ethylhexyl glycidyl ether (trade name "EX-121", manufactured by Nagase Chemtex Co., Ltd.): 10 parts by weight,

Photocationic polymerization initiator [brand name "CPI-100P", the product of San Afro Co., Ltd.]: 2.25 weight part.

Reference Example 1

The process paper A was peeled from the retardation film having the process paper A obtained above, and the surface shape of the retardation film on the surface (liquid crystal layer surface) shown was measured. H ² 425 is 7.70 × 10 ⁻⁵ . , H ² (212) was 7.51 × 10 ⁻⁵ . H ² 425 / H ² 212 of this surface is 1.03. In addition, this peeling surface (liquid crystal layer surface) was visually smooth.

Example 1

The polarizing plate was manufactured as follows.

The protective film was subjected to corona treatment. On the surface which corona-treated, the said ultraviolet curable adhesive agent was coated using the small diameter gravure coater. The protective film was bonded on the polarizer of a polarizing laminated film through the ultraviolet curable adhesive agent using the bonding roll. The ultraviolet curable adhesive agent was hardened by ultraviolet irradiation, the adhesive bond layer was formed, and the bonding film which consists of a laminated constitution of a protective film / adhesive layer / polarizer / primer layer / base film was obtained. The thickness of the adhesive bond layer was 0.8 micrometer.

The base film was peeled off from the obtained bonding film. The base film peeled easily, and obtained the polarizing plate which has a single-sided protective film which consists of a laminated constitution of a 1st protective film / adhesive layer / polarizer / primer layer.

Corona treatment was performed on the cyclic olefin resin film in retardation film which has process paper A. On the surface which corona-treated, the said ultraviolet curable adhesive agent was coated using the small diameter gravure coater. The retardation film which has process paper was bonded on the primer layer of the polarizing plate which has a single-sided protective film through an ultraviolet curable adhesive agent using the bonding roll. The ultraviolet curable adhesive was hardened by ultraviolet irradiation, and the adhesive bond layer was formed. The thickness of the adhesive bond layer was 0.8 micrometer.

Process paper A was peeled and the polarizing plate which consists of a 1st protective film / 1st adhesive bond layer / polarizer / primer layer / adhesive bond layer / retardation film was obtained. The power spectrum ratio H ² (425) / H ² (212) of the surface of the liquid crystal layer shown by peeling process paper A was measured, and the external appearance evaluation of the polarizing plate was performed. The arithmetic mean wave shape Wa of the surface on the opposite side to the polarizer in a retardation film was 50 nm or less. In addition, this peeling surface (liquid crystal layer surface) was visually smooth.

Comparative Example 1

A polarizing plate was produced in the same manner as in Example 1 except that the retardation film having the step A was changed to the retardation film having the step A. The power spectrum ratio H ² (425) / H ² (212) of the surface of the liquid crystal layer shown by peeling process paper B was measured, and the external appearance evaluation of the polarizing plate was performed. The arithmetic mean wave shape Wa of the surface on the opposite side to the polarizer in a retardation film was 50 nm or less. In addition, this peeling surface (liquid crystal layer surface) was visually smooth.

The above result is shown in Table 2.

Reference Example 2

The process paper C was peeled from the retardation film having the process paper C obtained above, and the surface shape of the retardation film on the peeling surface was measured. H ² 425 is 6.09 × 10 ⁻⁴ , and H ² (212) Was 1.08 × 10 ⁻³ , the surface roughness (Ra) was 344 nm, the Kurtosis Pku was 1.84, and the skewness Psk was +0.209. H ² 425 / H ² 212 of this surface is 0.56. In addition, this peeling surface (liquid crystal layer surface) was visually smooth.

Example 2

Polarizer process not created by a retardation film with an A in the process if for changing a phase difference film having a C except as in Example 1, expression is the power spectrum of the liquid crystal layer surface appeared to separate the C if the step ratio H ² (425) / H ² 212 is 10 or less, and the external appearance is favorable.

Reference Example 3

The surface shape of the retardation film on the peeling surface (liquid crystal layer surface) shown was measured by peeling the process paper D from the retardation film having the process paper D obtained above, and H ² (425) was 3.60 × 10 ⁻⁶ . , H ² (212) was 9.48 × 10 ⁻⁶ , surface roughness (Ra) was 212 nm, Kurtosis Pku was 3.051, and skewness Psk was −0.010. H ² 425 / H ² 212 of this surface is 0.38. In addition, this peeling surface (liquid crystal layer surface) was visually smooth.

Example 3

A polarizing plate that are created process not by a retardation film with an A in the process if for changing a phase difference film having a D except as in Example 1 expression is, the power spectrum of the liquid crystal layer surface appeared to separate the D if the step ratio H ² (425) / H ² 212 is 10 or less, and the external appearance is favorable.

According to this invention, even when a polarizing plate is equipped with a retardation film, it becomes difficult to visually recognize the unevenness | corrugation which arises in the visual recognition side surface of a polarizing plate, and can make the external appearance of a polarizing plate favorable.

2: polarizer
3: base film
4: protective film
5: liquid crystal layer
6: adhesive layer
10, 11: adhesive layer
20: retardation film
100, 101: polarizer

Claims (4)

The polarizer and the retardation film are laminated through the adhesive layer,
When the one-dimensional power spectrum of the period f (㎛) of the surface irregularities with H ² (f), and to the surface of the opposite side and the polarizer in the above retardation film satisfy the formula (1),
The said retardation film is a polarizing plate which is a film laminated | stacked on the image display element side.
H ² (425) / H ² (212) ≤10 (1) The polarizing plate according to claim 1, wherein the retardation film comprises a liquid crystal layer having a thickness of 0.5 to 5.0 μm and a base film having a thickness of 10 to 50 μm, and having an in-plane retardation value at a wavelength of 590 nm of 100 to 150 nm. . The polarizing plate according to claim 1 or 2, wherein the adhesive layer is a cured layer of an active energy ray-curable adhesive. Bonding a process sheet onto a retardation film to obtain a laminated film;
Peeling said process paper from said laminated film to obtain a retardation film;
Bonding a polarizer onto a retardation film via an adhesive to obtain a polarizing plate,
When the one-dimensional power spectrum of the period f (㎛) of the surface irregularities with H ² (f), the manufacturing method of the polarizing plate to to the bonded surface of the retardation film and in how the process satisfies the following formula (2) .
H ² (425) / H ² (212) ≤10 (2)

Images