JP5533217B2 - Retardation film and polarizing plate and display device using the same - Google Patents

Description

  The present invention relates to an optical member used in a display device, and more particularly to a retardation film. The present invention also relates to a polarizing plate and a display device using the retardation film.

  In recent years, display devices such as liquid crystal display devices and organic electroluminescence (EL) display devices have been widely used in televisions, computers, mobile phones, and the like. There is also a strong demand for cost.

  As an example of the display device, a configuration example of a liquid crystal display device is shown in FIG. The liquid crystal display device shown in FIG. 3 has a liquid crystal cell 6, and a phase difference plate 5 and a polarizing plate 4 are arranged on one side of the liquid crystal cell 6. The polarizing plate 4 has a polarizer 3 in the center, and a polarizer protective film 1b is formed on both sides of the polarizer 3 with an adhesive layer 2 interposed therebetween.

  The polarizing plate used in the display device is an optical member having a function of transmitting one of orthogonal polarization components and shielding the other. As this polarizing plate, one having a polarizer protective film formed on one side or both sides of a polarizer is generally used. This polarizer has a function of transmitting only light having a specific vibration direction, and a uniaxially stretched polyvinyl alcohol (PVA) film dyed with iodine or a dichroic dye is widely used. .

  Moreover, the polarizer protective film bears functions such as supporting the polarizer and imparting practical strength to the entire polarizing plate and physically protecting the surface of the polarizer. Therefore, the polarizer protective film is required to have performance such as having practical strength, good transparency, and low optical nonuniformity such as moire pattern. Therefore, as the polarizer protective film, a triacetyl cellulose (hereinafter sometimes referred to as TAC) film that is a cellulose film is generally used.

Incidentally, the retardation film is an optical member having birefringence that causes a phase difference between orthogonally polarized components, and is used for so-called optical compensation for compensating the phase difference.
A retardation film having a positive A plate characteristic is obtained when normal light is used as light whose refractive index does not change no matter which direction the light enters, and abnormal light is used as light whose refractive index changes according to the incident direction of light. A retardation film having an optical axis inside and an extraordinary refractive index larger than that of ordinary light. The retardation film having the positive A plate characteristic is, for example, for maintaining the orthogonality when the two polarizing plates are arranged orthogonally (crossed Nicols) in an oblique vision in a vertical alignment (VA) mode type liquid crystal display device. Therefore, it is disposed between the polarizer and the liquid crystal cell and used as a so-called viewing angle widening film. Further, in the organic EL display device, a shielding effect that does not allow the mirror surface of the transparent electrode to be visually recognized from the outside can be obtained by arranging a retardation film having an appropriate positive A plate characteristic between the polarizer and the transparent electrode. .

  However, the TAC film generally used as the polarizer protective film is difficult to use as a retardation film having positive A plate characteristics. This is because the moisture resistance of the TAC film is insufficient, and the dimensions of the film change due to water absorption, and the performance of the polarizer is deteriorated due to the transmitted moisture. Further, to impart positive A plate characteristics to the TAC itself, a phase difference film having positive A plate characteristics is separately employed to compensate for the retardation of the polarizer, or the positive A plate is provided on the surface of the TAC film. There is also a problem that it is difficult to form a retardation layer having characteristics specially.

  Then, in order to eliminate deficiency of moisture resistance of the TAC film, it has been proposed to use polypropylene having excellent moisture resistance as a polarizer protective film (Patent Documents 1 and 2). Patent Document 1 discloses that an optical film using polypropylene polymerized using a metallocene catalyst is suitable for protecting a polarizer by having features such as small haze and excellent transparency. Yes.

Patent Document 2 discloses that a protective film for a polarizing plate is obtained by stretching a raw film of a polypropylene resin obtained by film formation to develop a retardation, and bonding the retardation film to a polarizer. Discloses a composite polarizing plate having a function as a retardation film.
However, when the retardation is expressed by the stretching treatment, the obtained retardation value depends on the thickness of the film. Therefore, of course, the thickness of the film cannot be made thinner than the thickness necessary for obtaining a desired retardation value, which may hinder the thinning of the polarizing plate and the display device. In addition, variations in phase difference are likely to occur due to fluctuations in the control of the stretching process, and furthermore, the internal heat shrinkage stress accumulates in the film due to stretching, so that the dimensional change tends to be large under high temperature and high humidity environments. Occurs.

JP 2008-146023 A JP 2007-316603 A

  The present invention has been made under such circumstances, and an object of the present invention is to find a technique for imparting positive A plate characteristics to polypropylene polymerized using a metallocene catalyst, and to have positive A plate characteristics and appearance. And providing a retardation film that can be used as a polarizer protective film. Further, by using the retardation film, it is possible to further reduce the thickness and cost of the polarizing plate and the display device.

As a result of intensive studies to achieve the above object, the present inventors have found that the problem can be solved by using a specific amide compound for the polypropylene copolymer. The present invention has been completed based on such findings.
That is, the gist of the present invention is as follows.

1. A polypropylene resin composition comprising polypropylene polymerized using a metallocene catalyst and a 1,2,3-propanetricarboxylic acid amide compound and / or 1,2,3,4-butanetetracarboxylic acid amide compound, and positive A A retardation film having plate characteristics.
2. 2. The retardation film as described in 1 above, wherein the polypropylene is a random copolymer of propylene and α-olefin.
3. 3. The retardation film as described in 1 or 2 above, wherein the compounding amount of the carboxylic acid amide compound is 0.1 to 3 parts by mass with respect to 100 parts by mass of the polypropylene.
4). The retardation film as described in any one of 1 to 3 above, which is not stretched.
5. 5. A polarizing plate, wherein the retardation film according to any one of 1 to 4 is provided on at least one surface of a polarizer.
6). 6. A display device using the polarizing plate described in 5 above.

According to the present invention, it is possible to obtain a retardation film having positive A plate characteristics and excellent appearance and usable as a polarizer protective film. In addition, the present inventors have found that an in-plane retardation that provides positive A plate characteristics can be expressed by mixing an amide compound with polypropylene polymerized using a metallocene catalyst. Since the in-plane retardation value developed at this time depends on the mixing ratio of the amide compound, the desired in-plane retardation value can be adjusted by increasing or decreasing the mixing ratio of the amide compound.
Furthermore, by using the retardation film of the present invention, a thin and low-cost polarizing plate and display device can be obtained.

It is a figure which shows the structural example of the polarizing plate of this invention. It is a figure which shows the structural example (example in which the phase difference film which has a positive A plate characteristic serves as a polarizer protective film) of the liquid crystal display device of this invention. It is a figure which shows the structural example (example which has a polarizer protective film and retardation film which has a positive A plate characteristic) of the liquid crystal display device of this invention.

[Phase difference film]
The retardation film of the present invention is a polypropylene containing polypropylene polymerized using a metallocene catalyst and a 1,2,3-propanetricarboxylic acid amide compound and / or 1,2,3,4-butanetetracarboxylic acid amide compound. It consists of a resin composition and has positive A plate characteristics.
Hereinafter, the retardation film will be described in detail.

《Polypropylene polymerized using metallocene catalyst》
The polypropylene polymerized using the metallocene catalyst used in the present invention is a propylene polymer synthesized by a polymerization reaction using the metallocene catalyst described later. Polypropylene polymerized using a metallocene catalyst generally has a uniform molecular weight and crystallinity compared to polypropylene polymerized using a Ziegler-Natta catalyst, which has low molecular weight and low crystallinity. Have Therefore, a retardation film using polypropylene polymerized using a metallocene catalyst is higher in transparency than a retardation film using polypropylene polymerized using a Ziegler-Natta catalyst. Therefore, in the present invention, polypropylene polymerized using a metallocene catalyst is used as one of the essential components of the mixed resin constituting the retardation film of the present invention.

The polypropylene polymerized using the metallocene catalyst may be either a propylene homopolymer or a copolymer of propylene and an α-olefin, and from the viewpoint of optical properties, a random copolymer of propylene and an α-olefin. It is preferable that
As the α-olefin, ethylene and 1-olefin having 4 to 18 carbon atoms are preferably used. Specifically, ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-heptene, 4- Preferable examples include methyl-pentene-1, 4-methyl-hexene-1, 4,4-dimethylpentene-1. From the viewpoint of the balance between transparency and heat resistance, the proportion of propylene units in the copolymer is preferably 80 mol% or more and less than 100 mol%, and the comonomer is more than 0 to 20 mol% or less. As the comonomer, the α-olefin is not limited to one type, and two or more types can be used, and the copolymer can be a multi-component copolymer such as a terpolymer. In addition, the content of the structural unit derived from a comonomer in a copolymer can be calculated | required by the measurement of an infrared (IR) absorption spectrum.

(Metallocene catalyst)
As the metallocene catalyst, a known catalyst can be appropriately used. Generally, a group 4-6 transition metal compound such as Zr, Ti, or Hf, particularly a group 4 transition metal compound and an organic transition metal compound having a cyclopentadienyl group or a cyclopentadienyl derivative group is used. be able to.

  As the group of the cyclopentadienyl derivative, an alkyl substituent such as pentamethylcyclopentadienyl, or a group in which two or more substituents are combined to form a saturated or unsaturated cyclic substituent may be used. Typically, an indenyl group, a fluorenyl group, an azulenyl group, or a partial hydrogenated product thereof can be given. Moreover, what combined several cyclopentadienyl group with the alkylene group, the silylene group, the germylene group etc. can be mentioned suitably.

(Cocatalyst)
In the production of polypropylene, a cocatalyst can be used along with the metallocene catalyst. The cocatalyst was selected from the group consisting of an aluminum oxy compound, an ionic compound capable of reacting with the metallocene compound to convert the metallocene compound component into a cation, or a Lewis acid, a solid acid, or a layered silicate. At least one compound can be used. Moreover, an organoaluminum compound can be added with these compounds as needed.

(Physical properties of polypropylene using metallocene catalyst)
As a method (polymerization method) for synthesizing polypropylene using the metallocene catalyst, a slurry method using an inert solvent, a gas phase method without using a solvent, a solution method, or a polymerization in the presence of these catalysts. Examples thereof include a bulk polymerization method using a monomer as a solvent.

  The polypropylene polymerized using the metallocene catalyst thus obtained preferably has a melting point (Tm) of 120 to 170 ° C. If the melting point (Tm) is within the above range, the heat resistance of the optical film is improved, and it can be used for applications requiring heat resistance such as a polarizing plate. Here, the melting point is evaluated at a temperature at which the peak of the highest intensity appears in the melting curve measured by a differential scanning calorimeter (DSC), and 10 mg of a polypropylene copolymer press film is placed at 230 ° C. in a nitrogen atmosphere. After the heat treatment at 5 ° C., the temperature is lowered to 30 ° C. at a temperature decrease rate of 10 ° C./min, kept at 30 ° C. for 5 minutes, and further heated from 30 ° C. to 230 ° C. at a temperature increase rate of 10 ° C./min. This is the calculated value.

<Amide compound>
The amide compounds used in the present invention are 1,2,3-propanetricarboxylic acid amide compounds and 1,2,3,4-butanetetracarboxylic acid amide compounds, which are used alone or simultaneously. An amide compound is a product obtained by amidation reaction of a predetermined polycarboxylic acid or acid anhydride thereof and one or more monoamines according to a conventionally known method. Conventionally, transparency of polyolefin resin, As a crystal nucleating agent for improving crystallinity and rigidity, techniques utilizing an amide compound have been proposed (for example, Japanese Patent No. 3401868, JP-A-7-242610, WO00 / 52089), and generally It is known that polypropylene can be added to polymerized using Ziegler-Natta catalysts. In the present invention, it is used for imparting an in-plane retardation that is a positive A plate characteristic, and is further excellent in heat resistance and compatibility with polypropylene, and may cause bleed defects (bleed out) after blending. Absent.

  As the 1,2,3-propanetricarboxylic acid amide compound, specifically, 1,2,3-propanetricarboxylic acid trihexylamide, 1,2,3-propanetricarboxylic acid tridodecylamide, 1,2,3 -Propanetricarboxylic acid trioctadecylamide, 1,2,3-propanetricarboxylic acid trianilide, 1,2,3-propanetricarboxylic acid tricyclohexylamide, 1,2,3-propanetricarboxylic acid tri (2-methylcyclohexylamide), 1,2,3-propanetricarboxylic acid tri (3-methylcyclohexylamide), 1,2,3-propanetricarboxylic acid tri (4-methylcyclohexylamide), 1,2,3-propanetricarboxylic acid tri (2-ethyl) (Cyclohexylamide) 1,2,3-propanetricarbo Acid tri (3-ethylcyclohexylamide), 1,2,3-propanetricarboxylic acid tri (4-ethylcyclohexylamide), 1,2,3-propanetricarboxylic acid tri (2-n-propylcyclohexylamide), 1, 2,3-propanetricarboxylic acid tri (3-n-propylcyclohexylamide), 1,2,3-propanetricarboxylic acid tri (4-n-propylcyclohexylamide), 1,2,3-propanetricarboxylic acid tri (2 -Iso-propylcyclohexylamide), 1,2,3-propanetricarboxylic acid tri (3-iso-propylcyclohexylamide), 1,2,3-propanetricarboxylic acid tri (4-iso-propylcyclohexylamide), 1, 2,3-propanetricarboxylic acid tri (2-n-butylsilane (Rohexylamide), 1,2,3-propanetricarboxylic acid tri (3-n-butylcyclohexylamide), 1,2,3-propanetricarboxylic acid tri (4-n-butylcyclohexylamide), 1,2,3 Propanetricarboxylic acid tri (2-iso-butylcyclohexylamide), 1,2,3-propanetricarboxylic acid tri (3-iso-butylcyclohexylamide), 1,2,3-propanetricarboxylic acid tri (4-iso- Butylcyclohexylamide), 1,2,3-propanetricarboxylic acid tri (2-sec-butylcyclohexylamide), 1,2,3-propanetricarboxylic acid tri (3-sec-butylcyclohexylamide), 1,2,3 -Propanetricarboxylic acid tri (4-sec-butylcyclohexylamide) 1,2,3-propanetricarboxylic acid tri (2-tert-butylcyclohexylamide), 1,2,3-propanetricarboxylic acid tri (3-tert-butylcyclohexylamide), 1,2,3-propanetricarboxylic acid Tri (4-tert-butylcyclohexylamide), 1,2,3-propanetricarboxylic acid tri (4-n-pentylcyclohexylamide), 1,2,3-propanetricarboxylic acid tri (4-n-hexylcyclohexylamide) 1,2,3-propanetricarboxylic acid tri (4-n-heptylcyclohexylamide), 1,2,3-propanetricarboxylic acid tri (4-n-octylcyclohexylamide), 1,2,3-propanetricarboxylic acid Tri [4- (2-ethylhexyl) cyclohexylamide], 1 2,3-propanetricarboxylic acid tri (4-n-nonylcyclohexylamide), 1,2,3-propanetricarboxylic acid tri (4-n-decylcyclohexylamide), 1,2,3-propanetricarboxylic acid [cyclohexyldi (2-methylcyclohexyl) triamide] and 1,2,3-propanetricarboxylic acid amide such as 1,2,3-propanetricarboxylic acid [dicyclohexyl (2-methylcyclohexyl) triamide]. These can be used alone or in appropriate combination of two or more.

  Specific examples of the 1,2,3,4-butanetetracarboxylic amide compound include 1,2,3,4-butanetetracarboxylic acid tetrahexylamide, 1,2,3,4-butanetetra. Carboxylic acid tetradodecylamide, 1,2,3,4-butanetetracarboxylic acid tetraoctadecylamide, 1,2,3,4-butanetetracarboxylic acid tetraanilide, 1,2,3,4-butanetetracarboxylic acid tetra Cyclohexylamide, 1,2,3,4-butanetetracarboxylic acid tetra (2-methylcyclohexylamide), 1,2,3,4-butanetetracarboxylic acid tetra (3-methylcyclohexylamide), 1,2,3 , 4-Butanetetracarboxylic acid tetra (4-methylcyclohexylamide), 1,2,3,4-butanetetracarboxylic acid tetra 2-ethylcyclohexylamide) 1,2,3,4-butanetetracarboxylic acid tetra (3-ethylcyclohexylamide), 1,2,3,4-butanetetracarboxylic acid tetra (4-ethylcyclohexylamide), 1, 2,3,4-butanetetracarboxylic acid tetra (2-n-propylcyclohexylamide), 1,2,3,4-butanetetracarboxylic acid tetra (3-n-propylcyclohexylamide), 1,2,3, 4-butanetetracarboxylic acid tetra (4-n-propylcyclohexylamide), 1,2,3,4-butanetetracarboxylic acid tetra (2-iso-propylcyclohexylamide), 1,2,3,4-butanetetra Carboxylic acid tetra (3-iso-propylcyclohexylamide), 1,2,3,4-butanetetracarbo Acid tetra (4-iso-propylcyclohexylamide), 1,2,3,4-butanetetracarboxylic acid tetra (2-n-butylcyclohexylamide), 1,2,3,4-butanetetracarboxylic acid tetra (3 -N-butylcyclohexylamide), 1,2,3,4-butanetetracarboxylic acid tetra (4-n-butylcyclohexylamide), 1,2,3,4-butanetetracarboxylic acid tetra (2-iso-butyl) Cyclohexylamide), 1,2,3,4-butanetetracarboxylic acid tetra (3-iso-butylcyclohexylamide), 1,2,3,4-butanetetracarboxylic acid tetra (4-iso-butylcyclohexylamide), 1,2,3,4-butanetetracarboxylic acid tetra (2-sec-butylcyclohexylamide), 1,2, 3,4-butanetetracarboxylic acid tetra (3-sec-butylcyclohexylamide), 1,2,3,4-butanetetracarboxylic acid tetra (4-sec-butylcyclohexylamide), 1,2,3,4- Butanetetracarboxylic acid tetra (2-tert-butylcyclohexylamide), 1,2,3,4-butanetetracarboxylic acid tetra (3-tert-butylcyclohexylamide), 1,2,3,4-butanetetracarboxylic acid Tetra (4-tert-butylcyclohexylamide), 1,2,3,4-butanetetracarboxylic acid tetra (4-n-pentylcyclohexylamide), 1,2,3,4-butanetetracarboxylic acid tetra (4- n-hexylcyclohexylamide), 1,2,3,4-butanetetracarboxylic acid tetra (4-n-he Tilcyclohexylamide), 1,2,3,4-butanetetracarboxylic acid tetra (4-n-octylcyclohexylamide), 1,2,3,4-butanetetracarboxylic acid tetra [4- (2-ethylhexyl) cyclohexyl Amide], 1,2,3,4-butanetetracarboxylic acid tetra (4-n-nonylcyclohexylamide), 1,2,3,4-butanetetracarboxylic acid tetra (4-n-decylcyclohexylamide), 1 1,2,3,4-butanetetracarboxylic acid [cyclohexyldi (2-methylcyclohexyl) tetraamide], 1,2,3,4-butanetetracarboxylic acid [dicyclohexyl (2-methylcyclohexyl) tetraamide], 3,4-butanetetracarboxylic amide and the like. These can be used alone or in appropriate combination of two or more. Moreover, 1,2,3-propanetricarboxylic acid amide and 1,2,3,4-butanetetracarboxylic acid amide may be used alone or in combination.

  Among the amide compounds, a residue obtained by removing an amino group from a monoamine is a cyclohexyl group or a cyclohexyl group having a linear or branched alkyl group having 1 to 4 carbon atoms as a substituent, particularly a methylcyclohexyl group. Certain amide compounds are more preferred. Specifically, 1,2,3-propanetricarboxylic acid tricyclohexylamide, 1,2,3-propanetricarboxylic acid tri (2-methylcyclohexylamide), 1,2,3-propanetricarboxylic acid tri (3-methyl) Cyclohexylamide), 1,2,3-propanetricarboxylic acid tri (4-methylcyclohexylamide), 1,2,3,4-butanetetracarboxylic acid tetracyclohexylamide, 1,2,3,4-butanetetracarboxylic acid Tetra (2-methylcyclohexylamide), 1,2,3,4-butanetetracarboxylic acid tetra (3-methylcyclohexylamide), 1,2,3,4-butanetetracarboxylic acid tetra (4-methylcyclohexylamide) Etc. are exemplified as preferred amide compounds. These can be used alone or in appropriate combination of two or more.

  The crystal system of the amide compound according to the present invention is not particularly limited as long as the effects of the present invention can be obtained, and any crystal system such as hexagonal crystal, monoclinic crystal, cubic crystal and the like can be used. These crystals are also known or can be prepared according to known methods.

  The amide compound used in the present invention preferably contains no impurities. However, the reaction intermediate or unreacted monoamide dicarboxylic acid or ester derived from the production process, diamide monocarboxylic acid or ester thereof, amide- Impurities such as a compound having an imide skeleton such as an imide structure or a bisimide structure may be contained. In the present invention, the purity of the amide compound is preferably 90% or more, more preferably 95% or more, and particularly preferably 97% by weight or more.

  The particle size of the amide compound used in the present invention is not particularly limited as long as the effects of the present invention can be obtained, but those having a particle size as small as possible are preferable from the viewpoint of dissolution time with respect to the molten polypropylene resin. Specifically, the maximum particle size is usually 200 μm or less, preferably 100 μm or less, more preferably 50 μm, and particularly preferably 10 μm or less. This particle size is a numerical value obtained by measuring by a laser diffraction light scattering method.

Examples of the method for producing the maximum particle size of the amide compound used in the present invention within the above range include a method of finely pulverizing using a conventional apparatus known in this field and classifying the same. Specifically, it is finely pulverized using a fluidized bed type counter jet mill (“100AFG (model number), manufactured by Hosokawa Micron Corporation), a supersonic jet mill (“ PJM-200 (model number) ”, manufactured by Nippon Pneumatic Co., Ltd.), etc. As an example, a classification method is exemplified.
In the present invention, the 5% weight reduction temperature of the amide compound is preferably 280 ° C. or higher, and more preferably 300 ° C. or higher. Such an amide compound having excellent thermal stability is preferable because it does not cause thermal decomposition when melt-mixed with a polypropylene resin and does not promote decomposition of the resin.

The compounding quantity with respect to the polypropylene of an amide compound can be suitably selected according to the value of desired in-plane phase difference. When the blending amount is increased, the value of the in-plane retardation obtained is increased, but on the other hand, whitening occurs due to bleeding or the like, which may cause poor appearance.
From the above viewpoint, the amount of the amide compound in the present invention is preferably 0.1 to 4 parts by mass, more preferably 0.1 to 3 parts by mass with respect to 100 parts by mass of polypropylene. More preferably, it is 0.1-2 mass parts, Most preferably, it is 0.3-1.5 mass parts. If the blending amount of the amide compound is within the above range, it can be adjusted to a retardation range generally required for a retardation film having positive A plate characteristics.

《Arbitrary component》
In the present invention, various additives and additive resins can be added as optional components of the polypropylene resin composition constituting the retardation film as desired.
For example, depending on the desired physical properties of the film, various olefin resins other than polypropylene polymerized using a metallocene catalyst can be blended as an additive resin within a range that does not impair the birefringence and transparency required for the retardation film. In addition, weather resistance improvers, abrasion resistance improvers, polymerization inhibitors, crosslinking agents, infrared absorbers, antistatic agents, adhesion improvers, leveling agents, thixotropic agents, coupling agents, plasticizers, Foaming agents, fillers, solvents and the like can be added.

As the weather resistance improving agent, an ultraviolet absorber or a light stabilizer can be used.
The ultraviolet absorber may be either inorganic or organic, and as the inorganic ultraviolet absorber, titanium dioxide, cerium oxide, zinc oxide or the like having an average particle diameter of about 5 to 120 nm can be preferably used. Examples of the organic ultraviolet absorber include benzotriazole-based compounds, specifically 2- (2-hydroxy-5-methylphenyl) benzotriazole, 2- (2-hydroxy-3,5-di-tert-). Amylphenyl) benzotriazole, 3- [3- (benzotriazol-2-yl) -5-tert-butyl-4-hydroxyphenyl] propionic acid ester of polyethylene glycol, and the like.

Examples of the light stabilizer include hindered amines, specifically 2- (3,5-di-tert-butyl-4-hydroxybenzyl) -2′-n-butylmalonate bis (1,2,2). , 6,6-pentamethyl-4-piperidyl), bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, tetrakis (2,2,6,6-tetramethyl-4-piperidyl)- 1,2,3,4-butanetetracarboxylate and the like.
Further, as the ultraviolet absorber or light stabilizer, a reactive ultraviolet absorber or light stabilizer having a polymerizable group such as a (meth) acryloyl group in the molecule can be used.

<Phase difference film>
The retardation film of the present invention has positive A plate characteristics. The positive A plate characteristic means that the light whose refractive index does not change no matter which direction the light is incident is normal light, and the light whose refractive index changes depending on the light incident direction is abnormal light, the optical axis is in-plane. It has an optical characteristic that the extraordinary refractive index is larger than the ordinary refractive index. That is, when the in-plane main refractive index is nx (slow axis direction), ny (fast axis direction), and the refractive index in the thickness direction is nz, the refractive index distribution is a positive value satisfying nx> ny = nz. A uniaxial optical element. Ideally, a positive uniaxial optical element whose refractive index distribution satisfies nx> ny = nz has an optical axis in one direction in the plane. Note that ny = nz includes not only the case where ny and nz are completely the same, but also the case where ny and nz are substantially the same. Here, the case where ny and nz are substantially the same includes, for example, a case where the absolute value of the difference between the in-plane retardation value and the thickness direction retardation value is 10 nm or less.

When used in a VA mode / IPS mode type liquid crystal display device, organic EL display device, etc., the retardation range generally required for a retardation film having a positive A plate characteristic is a wavelength of R589.5 nm. And it is 10-650 nm normally on the conditions of an incident angle of 0 degree, Preferably it is 20 nm-300 nm. By setting the above phase difference range at the wavelength R589.5 nm, the function of the optical element in each display device is exhibited synergistically. In particular, in the VA mode type liquid crystal display device, the contrast ratio in the oblique direction can be increased and the color shift amount in the oblique direction can be reduced.
The in-plane retardation can be set to a desired value by increasing or decreasing the mixing ratio of the amide compound. In addition to mixing the amide compound, the in-plane retardation value can be adjusted by performing a stretching treatment as necessary.

  The thickness of the retardation film is preferably in the range of 10 to 200 μm, more preferably 30 to 150 μm. When the thickness is 10 μm or more, the strength of the retardation film can be ensured. When the thickness is 200 μm or less, sufficient flexibility can be obtained, and since it is lightweight, handling is easy and cost is advantageous.

  The flexural modulus of the retardation film is preferably 700 MPa or more. This is because if the flexural modulus is within the above range, sufficient rigidity can be obtained when handled in a film state, and post-processing can be easily performed. Furthermore, the flexural modulus of the retardation film is more preferably 900 MPa or more. Furthermore, the flexural modulus of the optical film is more preferably 900 MPa or more. This is because if the pressure is 900 MPa or more, the in-plane retardation can be stabilized when manufactured by T-die extrusion. Here, the flexural modulus is measured according to JIS K7171.

  There is no restriction | limiting in particular as an adjustment method of the bending elastic modulus of a phase difference film, It can adjust with the following methods. For example, a method of selecting by the original properties (crystallinity, average molecular weight, etc.) of polypropylene, a method of adding a filler selected from inorganic or organic fillers to a resin, a method of adding a crosslinking agent, etc. Examples thereof include a method of mixing two or more different types of resins, a method of selecting a plasticizer composition of a curable resin, or a method of appropriately combining a plurality of these methods.

The tensile strength of the retardation film is preferably 20 MPa or more. When the pressure is 20 MPa or more, when the optical film is bonded to the polarizer via the adhesive layer by a roll-to-roll method, the orientation is not applied, and variation in retardation is unlikely to occur.
The performance of the polarizing plate provided with plate characteristics can be improved. Here, in this invention, tensile strength shall be measured based on ASTMD638 (Type4 conditions).

  The retardation film preferably has a melt flow rate (hereinafter sometimes referred to as MFR) of 0.5 to 50 g / 10 minutes, more preferably 7 g / 10 minutes or more. Here, MFR is a value measured according to JIS K7210, and the measurement conditions are 230 ° C. and load 21.18N. If the MFR of the retardation film is within the above range, it is preferable because distortion can be suppressed during formation of the unstretched film, and a retardation film having low birefringence can be obtained. Moreover, sufficient intensity | strength as a phase difference film is obtained and a post-process can be performed easily. Furthermore, since the MFR can be easily stabilized in the production lot, stable molding can be performed, and the amount of additives such as the MFR adjusting agent can be suppressed, so that the physical properties are not adversely affected. In addition, adjustment of MFR of polypropylene can be performed by a general MFR adjusting agent such as an organic peroxide.

  The retardation film can be subjected to easy adhesion treatment on the surface in contact with the polarizer in order to improve adhesion. Examples of the easy adhesion treatment include surface treatment such as corona treatment, plasma treatment, low-pressure UV treatment, and saponification treatment, and a method of forming an anchor layer, and these can be used in combination. Among these, a corona treatment, a method of forming an anchor layer, and a method of using these in combination are preferable.

  In addition, a functional layer is laminated on the surface of the retardation film, and various functions, for example, high hardness and scratch resistance, so-called hard coat function, anti-fogging coat function, anti-fouling coating function, anti-glare coating A function, an antireflection coating function, an ultraviolet shielding coating function, an infrared shielding coating function, and the like can also be imparted.

<< Method for producing retardation film >>
The retardation film is prepared by mixing polypropylene polymerized using a metallocene catalyst, an amide compound, and various additives and additive resins as required, and heat-melting, followed by extrusion coating molding method, casting method, It can be manufactured by being molded into a film shape by various molding methods such as a T-die extrusion molding method, an inflation method, and an injection molding method.
The heating temperature during processing is usually in the range of 160 to 250 ° C, preferably 190 to 250 ° C. When the heating temperature is within the above range, a retardation film having better performance stability can be obtained.

  The retardation film of the present invention may or may not be stretched. There is no in-plane retardation or internal heat shrinkage stress due to stretching, making it easy to stably produce high-quality retardation films and reducing costs by reducing the number of steps. From the viewpoint of reducing the cost of the film, it is preferable not to perform the stretching treatment.

[Polarizer]
In the polarizing plate of the present invention, the retardation film of the present invention is provided as a polarizer protective film on at least one surface of the polarizer. As a method of forming a polarizing plate, a retardation film may be prepared first, and then bonded to a polarizer via an adhesive layer, or a retardation film may be directly formed on a polarizer. May be. The polarizing plate of the present invention is a high value-added polarizing plate provided with positive A plate characteristics. In addition, the retardation film of the present invention can be made thinner than a thickness necessary for obtaining a desired retardation value only by stretching, so that a thin and low-cost polarizing plate can be obtained. .
In FIG. 1, the structural example of the polarizing plate of this invention is shown. In FIG. 1, 3 is a polarizer, and the retardation film of the present invention is formed as a polarizer protective film 1a via an adhesive layer 2 on one side thereof.
The polarizing plate 4 is comprised as a whole.

《Polarizer》
As the polarizer used in the polarizing plate, any polarizer may be used as long as it has a function of transmitting only light having a specific vibration direction. For example, a PVA-based film is stretched, and iodine or a dichroic dye is used. Dyed PVA polarizers; polyene polarizers such as dehydrated PVA and polyvinyl chloride dehydrochlorination; reflective polarizers using cholesteric liquid crystals; thin film crystal film polarizers, etc. Of these, a PVA polarizer is preferably used.
Examples of PVA polarizers include hydrophilic polymers such as PVA films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymer partially saponified films, and two colors such as iodine and dichroic dyes. And uniaxially stretched by adsorbing the active substance. Among these, a polarizer composed of a PVA film and a dichroic substance such as iodine is preferably used. The thickness of these polarizers is not particularly limited, and is generally about 1 to 100 μm.

<< Polarizing plate manufacturing method >>
The polarizing plate is, for example, a process of uniaxially stretching a PVA film as described above, a process of dyeing a PVA resin film with a dichroic dye, and adsorbing the dichroic dye, and a dichroic dye being adsorbed. A process for treating a PVA-based film with an aqueous boric acid solution, a step for washing with water after the boric acid aqueous solution treatment, and a uniaxially stretched PVA-based film on which dichroic dyes are adsorbed and oriented by applying these steps It is manufactured through a process of attaching an optical film.

The optical film for protecting a polarizer can be attached by an adhesive layer provided by applying an adhesive on either or both sides of a retardation film or a polarizer.
For the formation of the adhesive layer, it is preferable to use a PVA adhesive. The PVA-based adhesive contains a PVA-based resin and a crosslinking agent. Examples of the PVA-based resin include PVA obtained by saponifying polyvinyl acetate and its derivatives, and a non-polymerizable copolymer with vinyl acetate. Saponification products of copolymers with monomers such as saturated carboxylic acids and esters thereof and α-olefins, modified PVA obtained by subjecting PVA to acetalization, urethanization, etherification, grafting or phosphoric esterification, etc. It is done. These PVA resins can be used singly or in combination of two or more.
The degree of polymerization of the PVA resin is not particularly limited, but since the adhesiveness and the like are improved, the average degree of polymerization is about 100 to 3000, preferably 500 to 3000, and the average saponification degree is about 85 to 100 mol%, preferably It is preferable to use about 90-100 mol%.

  In the present invention, the polarizer and the adhesive layer are treated with, for example, an ultraviolet absorber such as a salicylic acid ester compound, a benzophenol compound, a benzotriazole compound, a cyanoacrylate compound, or a nickel complex compound. The ultraviolet absorbing ability may be imparted.

  The adhesive layer is formed by applying an adhesive to either or both sides of the retardation film or the polarizer. The thickness of the adhesive layer is preferably 0.01 to 10 μm, more preferably 0.03 to 5 μm, since it is not preferable in terms of the adhesiveness of the retardation film if the thickness after drying becomes too thick.

  When the retardation film is bonded to the polarizer, surface treatment such as corona treatment, plasma treatment, low-pressure UV treatment, saponification treatment or an anchor layer is applied to the surface of the retardation film in contact with the polarizer to improve adhesion. Easy adhesion treatment such as a forming method can be performed. Of these, a corona treatment, a method of forming an anchor layer, and a method of using these in combination are preferable.

Next, an adhesive layer is formed on the surface subjected to the easy adhesion treatment as described above, and the polarizer and the retardation film are bonded through the adhesive layer.
Bonding of the polarizer and the retardation film can be performed with a roll laminator or the like. The heating drying temperature and drying time are appropriately determined according to the type of adhesive.

(Other)
In the polarizing plate in which the retardation film of the present invention is formed on one surface of the polarizer, the retardation film of the present invention can be formed on the other surface of the polarizer as necessary. A film made of a resin can also be formed. Examples of films made of other resins include polyethylene terephthalate films, polycarbonate films, cyclic polyolefin films, maleimide resin films, and fluorine resin films. The film made of the other resin may be a retardation film having a specific retardation.

The polarizing plate is preferably a laminate having at least one hard coat layer in order to improve surface properties and scratch resistance. Examples of the hard coat layer include ultraviolet curable resins such as ultraviolet curable acrylic urethane, ultraviolet curable epoxy acrylate, ultraviolet curable (poly) ester acrylate, and ultraviolet curable oxetane, silicone resins, acrylic resins, and urethane resins. Examples thereof include a hard coat layer made of a hard coat agent, and a hard coat layer made of an ultraviolet curable resin is preferable from the viewpoint of transparency, scratch resistance, and chemical resistance. One or more of these hard coat layers can be used.
As for the thickness of a hard-coat layer, 0.1-100 micrometers is preferable, Especially preferably, it is 1-50 micrometers, More preferably, it is 2-20 micrometers. Further, a primer treatment can be performed between the hard coat layers.

  Further, the polarizing plate can be subjected to a known anti-glare treatment such as anti-reflection or low-reflection treatment as necessary.

[Display device]
The retardation film and polarizing plate of the present invention can be preferably used for various display devices. Since the retardation film of the present invention has positive A plate characteristics and can be used as a polarizer protective film, it can be formed as a polarizer protective film of a polarizing plate having an optical compensation function. This can contribute to the simplification of the configuration of the display device using and the improvement of productivity.
In addition, the retardation film of the present invention can be used in a display device in combination with a polarizing plate not imparted with positive A plate characteristics without being used as a polarizer protective film.

The display device is not particularly limited as long as it uses a polarizing plate and requires positive A plate characteristics, and examples thereof include a liquid crystal display including a liquid crystal cell, an organic EL display device, and a touch panel. In the case of a liquid crystal display, an image display device is generally formed by appropriately assembling components such as a liquid crystal cell, an optical film, and an illumination system as necessary, and incorporating a drive circuit. In the invention, the configuration of the image display device is not particularly limited, except that the above polarizing plate is used and the positive A plate characteristic is required. For example, an appropriate image display device such as an image display device in which a polarizing plate is disposed on one side or both sides of a liquid crystal cell, or a backlight or a reflection plate as an illumination system is exemplified. As the liquid crystal cell, any type such as a TN type, an STN type, or a π type can be used. When configuring an image display device, for example, appropriate components such as a diffusion plate, an antiglare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusion plate, and a backlight are placed at appropriate positions. A layer or two or more layers can be arranged.
An example of a liquid crystal display device including a liquid crystal cell and an example of an organic EL display device will be described below.

<< Liquid Crystal Display Device Including Liquid Crystal Cell >>
The polarizing plate of the present invention is suitably used by being laminated, for example, on a liquid crystal cell.
As an example of the display device of the present invention, FIGS. 2 and 3 show configuration examples of a liquid crystal display device including a liquid crystal cell. FIG. 2 shows an example in which the retardation film having positive A plate characteristics of the present invention is used also as a polarizer protective film of a polarizing plate. FIG. 3 shows that the retardation film having the positive A plate characteristic of the present invention is not used as a polarizer protective film, and both the retardation film and the polarizer protective film are used as constituent members of a liquid crystal display device. This is an example.

  In FIG. 2, 6 indicates a liquid crystal cell. Examples of the liquid crystal cell 6 include an active matrix drive type typified by a thin film transistor type and a simple matrix drive type typified by a twist nematic type and a super twist nematic type. The polarizing plate 4 is laminated on the liquid crystal cell 6 via an adhesive layer (not shown). The polarizing plate 4 has a polarizer 2 at the center, and a positive A made of the retardation film of the present invention through an adhesive layer 3 on the surface side where the liquid crystal cell of the polarizer 2 and the polarizing plate are disposed. A polarizer protective film 1 a having plate characteristics is laminated, and a polarizer protective film 1 b not having positive A plate characteristics is laminated on the other surface side of the polarizer 2. When laminating the polarizing plate 4 and the liquid crystal cell 6, an adhesive layer may be provided on the polarizing plate 4 and / or the liquid crystal cell 6 in advance. When an optical compensation function other than the positive A plate characteristic is required, an optical film having a necessary optical compensation function can be appropriately employed as a constituent member of the display device.

  In FIG. 3, 6 indicates a liquid crystal cell. As the liquid crystal cell 6, those exemplified above can be used. On this liquid crystal cell 6, a retardation film 5 made of a retardation film having a positive A plate property of the present invention is laminated via an adhesive layer (not shown), and an adhesive layer ( The polarizing plate 4 is laminated via a not-shown). The polarizing plate 4 has a polarizer 3 in the center, and a polarizer protective film 1b having no positive A plate characteristics is laminated on both surfaces of the polarizing plate 4 with an adhesive layer 2 interposed therebetween. When laminating the polarizing plate 4 and the retardation plate 5 and the retardation plate 5 and the liquid crystal cell 6, an adhesive layer may be provided on the polarizing plate 4, the retardation plate 5 and the liquid crystal cell 6 in advance. In addition, as a polarizer protective film which does not have a positive A plate characteristic, the TAC film, the polypropylene film polymerized using the metallocene catalyst with which the amide compound is not mixed, etc. can be used. Further, when an optical compensation function other than the positive A plate characteristic is required, an optical film having the necessary optical compensation function can be appropriately employed as a constituent member of the display device.

The pressure-sensitive adhesive for laminating the polarizing plate and the liquid crystal cell is not particularly limited. For example, an acrylic pressure-sensitive adhesive is excellent in optical transparency, exhibits appropriate wettability, cohesiveness, and adhesive pressure-sensitive adhesive properties, and is weather resistant. It is preferable because it is excellent in properties and heat resistance.
The pressure-sensitive adhesive is required to be excellent in optical transparency, moderate wettability, cohesiveness, adhesive properties such as adhesion, weather resistance, heat resistance and the like. Furthermore, the moisture absorption rate is low in terms of prevention of foaming and peeling phenomena due to moisture absorption, deterioration of optical characteristics due to thermal expansion differences, prevention of warping of liquid crystal cells, and the formation of high-quality and durable image display devices. Therefore, a pressure-sensitive adhesive layer having excellent heat resistance is required.

  Application of the above-mentioned pressure-sensitive adhesive to the polarizing plate is, for example, 10 to 40% by mass in which a base polymer or a composition thereof is dissolved or dispersed in a solvent composed of a single solvent or a mixture of appropriate solvents such as toluene and ethyl acetate. Prepare a pressure-sensitive adhesive solution to the extent, and apply it directly on the polarizing plate by an appropriate development method such as a coating method such as gravure coating, bar coating, roll coating, or casting method, or according to this method. Examples thereof include a method of forming an adhesive layer on a releasable base film and transferring it to a polarizing plate.

The pressure-sensitive adhesive layer can be provided on one side or both sides of the polarizing plate as a superimposed layer of different compositions or types. Moreover, when providing in both surfaces, the adhesive does not need to be the same composition in the front and back of a polarizing plate, and it is not necessary to be the same thickness. It can also be set as the adhesive layer of a different composition and different thickness.
The thickness of the pressure-sensitive adhesive layer can be appropriately determined according to the purpose of use and adhesive force, and is generally 1 μm to 500 μm, preferably 5 μm to 200 μm, particularly preferably 10 μm to 100 μm.

  The exposed surface of the pressure-sensitive adhesive layer is coated with an appropriate thin film such as a plastic film, if necessary, with an appropriate release agent such as a silicone film for the purpose of preventing contamination until it is put to practical use. It is preferable that the released release film is temporarily attached and covered. Thereby, it can prevent contacting an adhesive layer in the usual handling state.

(Organic EL display device)
The polarizing plate of the present invention can be suitably used for an organic EL display device.
Generally, in an organic EL display device, a transparent electrode, an organic light emitting layer, and a metal electrode are sequentially laminated on a transparent substrate to form a light emitter (organic electroluminescent light emitter).

  In the organic EL display device having such a configuration, the organic light emitting layer is formed of a very thin film having a thickness of about 10 nm. For this reason, the organic light emitting layer transmits light almost completely like the transparent electrode. As a result, light that is incident from the surface of the transparent substrate at the time of non-light emission, passes through the transparent electrode and the organic light emitting layer, and is reflected by the metal electrode is again emitted to the surface side of the transparent substrate. The display surface of the organic EL display device looks like a mirror surface.

  In an organic EL display device comprising an organic electroluminescent light emitting device comprising a transparent electrode on the surface side of an organic light emitting layer that emits light upon application of a voltage and a metal electrode on the back side of the organic light emitting layer, the surface of the transparent electrode A polarizing plate may be provided on the side, and a birefringent layer (retardation plate) may be provided between the transparent electrode and the polarizing plate.

Since the polarizing plate has a function of polarizing light incident from the outside and reflected by the metal electrode, there is an effect that the mirror surface of the metal electrode is not visually recognized by the polarization function. In particular, if the retardation plate is a λ / 4 plate used as a positive A plate and the angle between the polarization direction of the polarizing plate and the birefringent layer is adjusted to π / 4, the mirror surface of the metal electrode is completely Can be shielded.
That is, only the linearly polarized light component of the external light incident on the organic EL display device is transmitted by the polarizing plate. This linearly polarized light generally becomes elliptically polarized light by the phase difference plate, but becomes circularly polarized light when the phase difference plate is a λ / 4 plate and the angle formed by the polarization direction with respect to the polarizing plate is π / 4. This circularly polarized light is transmitted through the transparent substrate, the transparent electrode, and the organic thin film, is reflected by the metal electrode, is again transmitted through the organic thin film, the transparent electrode, and the transparent substrate, and becomes linearly polarized light again by the phase difference plate. And since this linearly polarized light is orthogonal to the polarization direction of a polarizing plate, it cannot permeate | transmit a polarizing plate. As a result, the mirror surface of the metal electrode can be completely shielded.

  The retardation film of the present invention can be used as the retardation plate for the purpose of shielding the mirror surface of the metal electrode.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by this example.
(Evaluation method)
(1) Measurement of in-plane retardation About retardation films obtained in Examples 1 to 7 and Comparative Example 1, a retardation measuring machine (“KOBRA (registered trademark) -WR” manufactured by Oji Scientific Instruments) was used. The in-plane phase difference was measured under the conditions of wavelength R589.5 nm and incident angle 0 degree.
(2) Measurement of tensile strength About the retardation film obtained in Examples 1-7 and Comparative Example 1, the tensile strength of the retardation film was measured based on ASTM D638 (Type 4 condition).
(3) Heat resistance test The polarizing plate obtained in Example 8 was left in an oven at a temperature of 90 ° C. and no humidity control for 1000 hours, and then the presence or absence of deformation or coloring of the polarizing plate was visually evaluated according to the following criteria. .
○: Deformation and coloring were not confirmed. Δ: Deformation or coloring was confirmed to some extent, but there was no problem in practical use. X: Significant deformation or coloring was confirmed. (4) Moisture and heat resistance test Polarized light obtained in Example 8 The plate was left in an oven at a temperature of 90 ° C. and a humidity of 95% HR for 1,000 hours, and then the presence or absence of deformation or coloring of the sample was visually evaluated according to the following criteria.
○: Deformation or yellowing was not confirmed. △: Deformation or yellowing was confirmed, but there was no problem in practical use. X: Significant deformation or yellowing was confirmed. (5) Appearance evaluation (bleed evaluation)
About the polarizing plate obtained in Example 8, the surface state of the film was observed, and the influence on the appearance by precipitation (bleeding / bleeding) of the amide compound on the surface was evaluated according to the following criteria.
○: Appearance defects such as whitening due to bleed were not confirmed △: Appearance defects such as whitening due to bleed were slightly confirmed, but there were no practical problems ×: Appearance defects such as whitening due to significant bleed were confirmed

Example 1
To 100 parts by mass of polypropylene polymerized using a metallocene catalyst (manufactured by Nippon Polypro Co., Ltd., Wintec (registered trademark), melting point 142 ° C., flexural modulus 900 MPa, hereinafter referred to as “mPP-A”), As an amide compound, 1.0 part by mass of 1,2,3-propanetricarboxylic acid tri (2-methylcyclohexylamide) (manufactured by Shin Nippon Rika Co., Ltd., “Rikaclear (registered trademark) PC1”) is blended and melted by heating. It was. A retardation film was obtained by T-die single layer extrusion molding with a film thickness of 100 μm under conditions of a processing temperature of 210 ° C. and a take-up roll temperature of 50 ° C. In addition, the extending | stretching process after a shaping | molding process was not performed.

(Example 2)
In Example 1, mPP-A was a polypropylene polymerized using a metallocene catalyst (manufactured by Nippon Polypro Co., Ltd., Wintech (registered trademark), melting point 135 ° C., flexural modulus 1200 MPa, hereinafter “mPP-B”. A retardation film was obtained in the same manner as in Example 1, except that it was expressed as).

(Example 3)
In Example 1, mPP-A was a polypropylene polymerized using a metallocene catalyst (manufactured by Nippon Polypro Co., Ltd., Wintech (registered trademark), melting point 125 ° C., flexural modulus 700 MPa, hereinafter “mPP-C”. A retardation film was obtained in the same manner as in Example 1, except that it was expressed as).

Example 4
In Example 1, a retardation film was obtained in the same manner as in Example 1 except that the amount of the amide compound was 0.1 parts by mass.

(Example 5)
In Example 1, a retardation film was obtained in the same manner as in Example 1 except that the amount of the amide compound was 0.5 parts by mass.

(Example 6)
In Example 1, a retardation film was obtained in the same manner as in Example 1 except that the amount of the amide compound was 3.1 parts by mass.

(Example 7)
In Example 1, a retardation film was obtained in the same manner as in Example 1 except that the processing temperature was changed from 210 ° C to 170 ° C.

(Comparative Example 1)
A retardation film was obtained in the same manner as in Example 1 except that no amide compound was used in Example 1.

Table 1 shows the evaluation results of the retardation films obtained in Examples 1 to 7 and Comparative Example 1.
In the retardation films of Examples 1 to 7, by mixing an amide compound with polypropylene polymerized using a metallocene catalyst, the retardation of the film is improved as compared with Comparative Example 1 in which no amide compound was mixed. Positive A plate characteristics were obtained. In addition, by comparing Examples 1 to 3, 6 and 7 with Examples 4 and 5, it was confirmed that when the compounding ratio of the amide compound in the resin composition was increased, the in-plane retardation value was increased. .
When polypropylene having a flexural modulus of 700 MPa was used in Example 3, there was variation in the in-plane retardation value at the end of the film, but this was not a problem for practical use, and sufficient in-plane It was confirmed to have a phase difference. In addition, when the mixing ratio of the amide compound of Example 6 was 3.1 parts by mass, the dispersion of the amide compound was not sufficient, and although in-plane retardation was observed, Since the phase difference is large, it can be preferably used when a large in-plane phase difference is required although stability is not so much required.
In Example 7, the processing temperature was as low as 170 ° C., but the dispersion of the amide compound was not sufficient, but the in-plane retardation slightly varied, but it was not a problem in practical use. It was confirmed to have a sufficient in-plane retardation.
In the retardation films obtained in Examples 1 to 7 and Comparative Example 1, the tensile strength was in the range of 27 to 35 MPa, and no particular problem was found in workability.

* 1, It is a compounding quantity (mass part) with respect to 100 mass parts of polypropylene.

(Example 8)
A PVA obtained by saponifying polyvinyl acetate on the both sides of a polarizer made of a polyvinyl alcohol film in which iodine is adsorbed and oriented with the retardation film (width 150 mm × length 150 mm) obtained in Example 1 A polarizing plate was obtained by using and bonding.
When the obtained polarizing plate was subjected to the above heat resistance test, moisture resistance test and bleed evaluation, the evaluation results were all good and good. From these results, it was confirmed that the polarizing plate using the retardation film of the present invention is a polarizing plate that has excellent heat resistance and moisture resistance and does not cause poor appearance.

  The retardation film of the present invention is suitable as a polarizer protective film because it has positive A plate characteristics and excellent appearance. Moreover, the polarizing plate obtained by combining the retardation film of the present invention and a polarizer can be effectively used for display devices such as a liquid crystal display including a liquid crystal cell, an organic electroluminescence display device, and a touch panel.

DESCRIPTION OF SYMBOLS 1a: Polarizer protective film which has a positive A characteristic 1b: Polarizer protective film which does not have a positive A characteristic 2: Adhesive layer 3: Polarizer 4: Polarizing plate 5: Phase difference plate which has a positive A characteristic 6: Liquid crystal cell

Claims (5)

A positive A comprising a polypropylene resin composition containing polypropylene polymerized using a metallocene catalyst and 1,2,3-propanetricarboxylic acid tri (2-methylcyclohexylamide) and not subjected to stretching treatment A retardation film having plate characteristics.   The retardation film according to claim 1, wherein the polypropylene is a random copolymer of propylene and an α-olefin.   The retardation film according to claim 1 or 2, wherein the compounding amount of the carboxylic acid amide compound is 0.1 to 3 parts by mass with respect to 100 parts by mass of the polypropylene. A retardation film according to any one of claims 1 to 3 is provided on at least one surface of a polarizer. A display device comprising the polarizing plate according to claim 4 .