KR20200023174A - Phase difference film, phase difference layer-provided polarizing plate, and method for producing phase difference film - Google Patents

Abstract

Provided is a retardation film having a light diffusion function. According to the present invention, the retardation film is made of a stretched resin film and has a haze value of 30% to 90%. According to an embodiment of the present invention, a retardation film capable of realizing an optical member having a light diffusion function can be realized.

Description

Retardation film, polarizing plate with retardation layer, and manufacturing method of retardation film {PHASE DIFFERENCE FILM, PHASE DIFFERENCE LAYER-PROVIDED POLARIZING PLATE, AND METHOD FOR PRODUCING PHASE DIFFERENCE FILM}

The present invention relates to a retardation film, a polarizing plate with a retardation layer, and a method for producing a retardation film.

BACKGROUND ART In recent years, with the spread of thin displays, an image display device (organic EL display device) equipped with an organic EL panel has been proposed. The organic EL panel has a highly reflective metal layer, and is likely to cause problems such as reflection of external light and background reflection. In view of this, it is known to prevent these problems by forming a polarizing plate (circular polarizing plate) with a phase difference layer on the viewer side. Moreover, it is known to improve a viewing angle by forming the polarizing plate with retardation layer in the visual recognition side of a liquid crystal display panel. As a polarizing plate with a general retardation layer, it is known that the retardation film and the polarizer are laminated so that the slow axis and the absorption axis form a predetermined angle (for example, 45 °) according to the use. Moreover, what represented the slow axis in the extending direction by extending | stretching a resin film as a typical retardation film is known (patent document 1). By the way, in the above image display apparatus, the light-diffusion layer may be laminated | stacked on optical members, such as a polarizing plate with a phase difference layer, for the purpose of improving visibility. However, when the light diffusing layer is laminated, the number of parts increases, and the cost increases.

Japanese Patent Publication No. 3325560

This invention is made | formed in order to solve the said conventional subject, The objective is to provide the retardation film which has a light-diffusion function, the polarizing plate with retardation layer provided with such a retardation film, and the manufacturing method of retardation film. .

The retardation film of this invention consists of a stretched resin film, and has a haze value of 30%-90%.

In one embodiment, the retardation film has a light transmittance of light having a wavelength of 445 nm incident at a 50 ° angle of incidence along a direction parallel to the stretching axis. It is smaller than the transmittance.

In one embodiment, the retardation film has a wave shape along the direction orthogonal to the stretching axis.

In one embodiment, in the said retardation film, the said resin film is a polycarbonate-type resin film.

In one embodiment, the retardation film consists of a uniaxially stretched resin film.

In one embodiment, the retardation film has a void in an area of 4 µm in the thickness direction on at least one surface thereof.

According to another situation of this invention, the polarizing plate with retardation layer is provided. This polarizing plate with retardation layer is provided with a polarizing plate and a retardation layer, and the said retardation layer is comprised by the said retardation film.

According to another situation of this invention, the manufacturing method of the said retardation film is provided. This manufacturing method includes immersing the stretched resin film in a liquid containing a good solvent and a poor solvent for the resin film.

In one embodiment, the immersion time with respect to the said liquid of the said resin film is 30 second-180 second.

According to embodiment of this invention, when the haze value is 30%-90% in the retardation film which consists of stretched resin films, the retardation film which can implement | achieve the optical member which has a light-diffusion function can be implemented.

EMBODIMENT OF THE INVENTION Hereinafter, although embodiment of this invention is described, this invention is not limited to these embodiment.

A. Retardation Film

The retardation film which concerns on one Embodiment of this invention consists of a resin film extended | stretched. The retardation film has a haze value of 30% to 90%. For this reason, the said retardation film has a light-diffusion function. Therefore, the retardation film which concerns on this embodiment is a retardation film which has a light-diffusion function, without requiring other structures, such as a light-diffusion layer.

In one embodiment, the retardation film makes Tp _(445-50) the light transmittance of the light of wavelength 445 nm which enters at the incidence angle of 50 degrees along the direction parallel to a stretching axis, and 50 degrees along the direction orthogonal to a stretching axis. Tp _(445-50) < Tv _(445-50) is satisfied when the transmittance of light having a wavelength of 445 nm incident at the incident angle of is set to Tv _(445-50) . The Tv _445-50 is preferably 1.1 times to 2.5 times the Tp _445-50 , and more preferably 1.3 times to 2 times.

That is, the retardation film has transmittance anisotropy. When such a phase difference film is used for an image display apparatus, what is called a veil-view image display apparatus which differs in visibility according to the angle (direction) to visually recognize can be implement | achieved.

The haze value of the retardation film is preferably 35% to 85%, more preferably 40% to 80%. Further, the transmittance of light having a wavelength W (nm) incident at an angle of incidence of θ (°) along a direction parallel to the stretching axis is set to Tp _w-θ and at an angle of incidence of θ (°) along a direction perpendicular to the stretching axis. Tp _(w-θ) <Tv _(w-θ) is satisfied when the transmittance of light having an incident wavelength W (nm) is Tv _w-θ (but 400 nm≤W <700 nm, and 30 °). ≤ θ ≤ 50 °).

The resin film constituting the retardation film is typically a polycarbonate resin film. Retardation film consists of a resin film uniaxially stretched typically. The retardation film typically has a wave shape along the direction orthogonal to the stretching axis. The retardation film typically has pores in an area of 4 μm in the thickness direction on the surface of at least one side. The haze value and the transmittance anisotropy of the retardation film can be realized by the wave shape and / or the vacancy.

The thickness and optical characteristics (in-plane retardation, thickness direction retardation, wavelength dispersion characteristic, etc.) of the retardation film may be appropriately set according to the use and the purpose. For example, when using a retardation film as a (lambda) / 4 plate, in-plane phase difference becomes like this. Preferably it is 100 nm-160 nm.

B. Resin Film

The retardation film consists of the resin film extended | stretched as mentioned above. As resin which comprises the said resin film, arbitrary appropriate resin can be used as long as the retardation film obtained satisfy | fills the said characteristic, For example, polycarbonate resin, cyclic olefin resin, cellulose resin, polyester resin, poly Vinyl alcohol resin, polyamide resin, polyimide resin, polyether resin, polystyrene resin, acrylic resin, polyester carbonate resin. Among these, polycarbonate resin can be used preferably.

As said polycarbonate resin, arbitrary appropriate polycarbonate resin can be used as long as the effect of this invention is acquired. Preferably, the polycarbonate resin is a structural unit derived from a fluorene dihydroxy compound, a structural unit derived from an isosorbide dihydroxy compound, an alicyclic diol, an alicyclic dimethanol, di, tri or polyethylene And a structural unit derived from at least one dihydroxy compound selected from the group consisting of glycol and alkylene glycol or spiroglycol. Preferably, the polycarbonate resin is a structural unit derived from a fluorene dihydroxy compound, a structural unit derived from an isosorbide dihydroxy compound, a structural unit derived from an alicyclic dimethanol and / or di A structural unit derived from tree or polyethylene glycol; More preferably, the structural unit derived from a fluorene type dihydroxy compound, the structural unit derived from an isosorbide type dihydroxy compound, and the structural unit derived from di, tri or polyethylene glycol are included. The polycarbonate resin may contain the structural unit derived from another dihydroxy compound as needed. In addition, the detail of the polycarbonate resin which can be preferably used for this invention is described, for example in Unexamined-Japanese-Patent No. 2014-10291, Unexamined-Japanese-Patent No. 2014-26266, the said reference is referred to in this specification. It is used as.

In one embodiment, the polycarbonate resin containing the unit structure derived from the dihydroxy compound represented by following General formula (1) can be used.

[Formula 1]

(In Formula (1), R ₁ to R ₄ are each independently a hydrogen atom, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C6-C20 cycloalkyl group, or a substituted or An unsubstituted C6-C20 aryl group, X represents a substituted or unsubstituted C2-C10 alkylene group, a substituted or unsubstituted C6-C20 cycloalkylene group, or a substituted or unsubstituted group An arylene group having 6 to 20 carbon atoms, and m and n each independently represent an integer of 0 to 5.

As a specific example of the dihydroxy compound represented by General formula (1), 9,9-bis (4-hydroxyphenyl) fluorene, 9,9-bis (4-hydroxy-3- methylphenyl) fluorene, 9, 9-bis (4-hydroxy-3-ethylphenyl) fluorene, 9,9-bis (4-hydroxy-3-n-propylphenyl) fluorene, 9,9-bis (4-hydroxy-3 Isopropylphenyl) fluorene, 9,9-bis (4-hydroxy-3-n-butylphenyl) fluorene, 9,9-bis (4-hydroxy-3-sec-butylphenyl) fluorene, 9,9-bis (4-hydroxy-3-tert-butylphenyl) fluorene, 9,9-bis (4-hydroxy-3-cyclohexylphenyl) fluorene, 9,9-bis (4-hydroxy Hydroxy-3-phenylphenyl) fluorene, 9,9-bis (4- (2-hydroxyethoxy) phenyl) fluorene, 9,9-bis (4- (2-hydroxyethoxy) -3- Methylphenyl) fluorene, 9,9-bis (4- (2-hydroxyethoxy) -3-isopropylphenyl) fluorene, 9,9-bis (4- (2-hydroxyethoxy) -3- Isobutylphenyl) fluorene, 9,9-bis (4- (2-hydroxyethoxy) -3-tert-butylphenyl) fluor , 9,9-bis (4- (2-hydroxyethoxy) -3-cyclohexylphenyl) fluorene, 9,9-bis (4- (2-hydroxyethoxy) -3-phenylphenyl) flu Orene, 9,9-bis (4- (2-hydroxyethoxy) -3,5-dimethylphenyl) fluorene, 9,9-bis (4- (2-hydroxyethoxy) -3-tert- Butyl-6-methylphenyl) fluorene, 9,9-bis (4- (3-hydroxy-2,2-dimethylpropoxy) phenyl) fluorene, and the like.

The polycarbonate resin is, in addition to the structural units derived from the dihydroxy compound, isosorbide, isomannide, isodec, spiroglycol, dioxane glycol, diethylene glycol (DEG), triethylene glycol (TEG), The structural unit derived from dihydroxy compounds, such as polyethyleneglycol (PEG) and bisphenol, may be included.

Details of the polycarbonate resin including a structural unit derived from a dihydroxy compound include, for example, Japanese Patent No. 5204200, Japanese Patent Application Laid-Open No. 2012-67300, Japanese Patent No. 3325560, WO2014 / 061677, and the like. It is described. The description of this patent document is incorporated herein by reference.

In one embodiment, polycarbonate-based resins comprising oligofluorene structural units can be used. As a polycarbonate resin containing an oligofluorene structural unit, resin containing the structural unit represented by the following general formula (2) and / or the structural unit represented by the following general formula (3) is mentioned, for example.

[Formula 2]

[Formula 3]

(In the said General formula (2) and the said General formula (3), R <_5> and R <_6> is respectively independently a direct bond, a substituted or unsubstituted C1-C4 alkylene group (preferably, C3-C3 of a main chain is is an alkylene group). R ₇ is a direct bond, a substituted or unsubstituted alkylene group having 1 to 4 carbon atoms of the substituted (preferably an alkylene group having the carbon number of 1 to 2 on the main chain). R ₈ ~R ₁₃ is each independently Hydrogen atom, substituted or unsubstituted C1-10 (preferably 1-4, more preferably 1-2) alkyl group, substituted or unsubstituted C4-10 (preferably 4-8, more preferred) Preferably, 4-7) aryl group, substituted or unsubstituted C1-C10 (preferably 1-4, more preferably 1-2) acyl group, substituted or unsubstituted C1-C10 (preferably Preferably it is 1-4, More preferably, 1-2, the alkoxy group, substituted or unsubstituted C1-C10 (preferably 1-4), Preferably an aryloxy group of 1 to 2), a substituted or unsubstituted acyloxy group of 1 to 10 (preferably 1 to 4, more preferably 1 to 2), a substituted or unsubstituted amino group, a substitution Or an unsubstituted C1-10 (preferably 1-4) vinyl group, a substituted or unsubstituted C1-C10 (preferably 1-4) ethynyl group, a sulfur atom having a substituent, or a substituent A silicon atom, a halogen atom, a nitro group, or a cyano group, and at least two adjacent groups in R ₈ to R ₁₃ may be bonded to each other to form a ring.)

In one embodiment, the fluorene ring included in the oligofluorene structural unit has a structure in which all of R ₈ to R ₁₃ are hydrogen atoms, or R ₈ and / or R ₁₃ is a halogen atom, acyl group, or nitro group , Cyano group, and sulfo group, and any one of R ₉ to R ₁₂ is a hydrogen atom.

The detail of the polycarbonate resin containing an oligofluorene structural unit is described, for example in Unexamined-Japanese-Patent No. 2015-212816. The description of this patent document is incorporated herein by reference.

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

In another embodiment, the retardation film is produced by continuously obliquely stretching the elongate resin film in the direction of the angle θ with respect to the longitudinal direction. By adopting oblique stretching, a long stretched film having an orientation angle (slow axis in the direction of angle θ) with respect to the longitudinal direction of the film is obtained, and roll-to-roll is possible, for example, when laminating with a polarizer, The manufacturing process can be simplified.

As a drawing machine used for diagonal drawing, the tenter type drawing machine which can add the feed force, the tension force, or the pulling force of the right and left different speeds in the horizontal and / or longitudinal direction, for example is mentioned. Although a tenter type drawing machine includes a horizontal uniaxial drawing machine and a simultaneous biaxial drawing machine, any suitable drawing machine can be used as long as the elongate resin film can be continuously diagonally stretched.

C. Method of Making Retardation Film

The retardation film described in the above item A can be produced by the production method of the present invention. The manufacturing method of this invention includes immersing the stretched resin film in the liquid containing the good solvent and the poor solvent with respect to the resin film. The stretched resin film is the resin film described in the above section B.

The liquid contains a good solvent and a poor solvent for the resin film as described above. As a good solvent and a poor solvent, arbitrary appropriate solvent can be used as long as the retardation film demonstrated by said A item is obtained. Ethyl acetate, methyl ethyl ketone, etc. are mentioned as a good solvent. Isopropyl alcohol is mentioned as a poor solvent. The mass ratio between the good solvent and the poor solvent is preferably 45:55 to 55:45.

Immersion time to the said liquid of a resin film becomes like this. Preferably it is 30 second-180 second, More preferably, it is 30 second-120 second, More preferably, it is 30 second-90 second. By immersing the stretched resin film in the liquid, an uneven shape (typically a wave shape along a direction orthogonal to the stretching axis of the resin film) may be formed on the surface of the resin film over time. For this reason, the haze value of a resin film may increase according to immersion time. Therefore, the retardation film which has a desired haze value can be obtained by setting the immersion time with respect to the said liquid of a resin film suitably.

In one embodiment, after immersing the said resin film in the said liquid, a drying process is performed. Drying conditions can be set suitably, For example, a drying temperature is 80 degreeC-120 degreeC, and a drying time is 30 second-3 minutes.

D. Polarizer with Retardation Layer

The retardation film described in item A can be applied to an optical member such as a polarizing plate with a retardation layer. Therefore, this invention includes the polarizing plate with retardation layer which has the said retardation film. The polarizing plate with retardation layer which concerns on embodiment of this invention is equipped with the retardation layer comprised by the polarizing plate and the said retardation film. The angle between the absorption axis of the polarizing plate and the slow axis of the retardation film may be appropriately set according to the use and the purpose. The angle is, for example, 38 ° to 52 °.

The polarizing plate typically has a polarizer and a protective layer arranged on at least one side of the polarizer. The polarizer is typically an absorption type polarizer.

Arbitrary suitable polarizers can be employ | adopted as a polarizer. For example, a single layer resin film may be sufficient as the resin film which forms a polarizer, and a laminated body of two or more layers may be sufficient as it.

As a specific example of the polarizer comprised from the single-layered resin film, Iodine or a dichroic dye is used for hydrophilic polymer films, such as a polyvinyl alcohol (PVA) type film, a partially formalized PVA type film, an ethylene vinyl acetate copolymerization type partial saponification film, etc. And polyene oriented films such as those subjected to dyeing treatment and stretching treatment with a dichroic substance, and dehydrochlorination products of PVA and dechlorination treatment products of polyvinyl chloride. Preferably, the polarizer obtained by dyeing PVA system film with iodine and extending | stretching uniaxially from the point which is excellent in an optical characteristic is used.

The dyeing with iodine is carried out by immersing the PVA film in an iodine aqueous solution. The draw ratio of the uniaxial stretching is preferably 3 to 7 times. Stretching may be performed after the dyeing treatment or may be performed while dyeing. Moreover, you may dye, extending | stretching. As needed, a swelling process, a crosslinking process, a washing process, a drying process, etc. are given to a PVA system film. For example, by immersing the PVA-based film in water prior to dyeing and washing with water, the PVA-based film can not only be cleaned of dirt or antiblocking agent, but also the PVA-based film can be swollen to prevent staining.

As a specific example of the polarizer obtainable using a laminated body, the laminated body of a resin base material and the PVA system resin layer (PVA system resin film) laminated | stacked on the said resin base material, or the PVA system number formed by apply | coating to the resin base material and the said resin base material The polarizer obtained using the laminated body with a layer is mentioned. The detail of the manufacturing method of such a polarizer is described, for example in Unexamined-Japanese-Patent No. 2012-73580. This publication is incorporated herein by reference in its entirety.

The thickness of a polarizer is 1 micrometer-80 micrometers, for example. In one embodiment, the thickness of a polarizer becomes like this. Preferably it is 1 micrometer-25 micrometers, More preferably, it is 3 micrometers-10 micrometers, Especially preferably, it is 3 micrometers-8 micrometers. If the thickness of a polarizer is such a range, the curl at the time of heating can be suppressed favorably and the external appearance durability at the time of favorable heating will be obtained.

The protective layer is formed of any suitable protective film that can be used as a film to protect the polarizer. As a specific example of the material used as the main component of the said protective film, cellulose resins, such as triacetyl cellulose (TAC), polyester type, polyvinyl alcohol type, polycarbonate type, polyamide type, polyimide type, polyether sulfone type And transparent resins such as polysulfone, polystyrene, polynorbornene, polyolefin, (meth) acrylic and acetate. Moreover, thermosetting resins, such as (meth) acrylic-type, urethane type, (meth) acrylic-type urethane type, an epoxy type, a silicone type, or ultraviolet curing type resin etc. are mentioned. In addition, glassy polymers, such as a siloxane polymer, are mentioned, for example. Moreover, the polymer film of Unexamined-Japanese-Patent No. 2001-343529 (WO01 / 37007) can also be used. As a material of this film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in the side chain can be used. For example, isobutene and N-methyl The resin composition which has the alternating copolymer which consists of maleimide, and an acrylonitrile styrene copolymer is mentioned. The polymer film may be, for example, an extrusion molded product of the resin composition.

The thickness of a protective film becomes like this. Preferably it is 10 micrometers-100 micrometers. The protective film may be laminated on the polarizer via an adhesive layer (specifically, an adhesive layer, an adhesive layer), or may be laminated on the polarizer in close contact (without an adhesive layer). As needed, in the protective film arrange | positioned at the outermost surface of the polarizing plate with retardation layer, surface treatment layers, such as a hard-coat layer, an anti-glare layer, and an antireflection layer, can be formed.

EXAMPLE

Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by these Examples. In addition, the measuring method and evaluation method of each characteristic are as follows.

(1) haze value

It measured using the haze meter (Murakami Color Science Research Institute make, brand name "HM-150") by the method of JIS 7136.

(2) transmittance

445 nm emitted light from a laser light source (coherent, product name "CUBE") was incident on the retardation film, and the transmitted light was detected by a detector (manufactured by Hamamatsu Corporation, product name 'Si photodiode S2592-03'). The incidence angle into the retardation film was 0 ° (front direction), ± 30 °, ± 40 °, and ± 50 ° along the direction parallel to the stretching axis, and the direction perpendicular to the stretching axis. Accordingly, ± 30 °, ± 40 °, and ± 50 °.

Example 1

1. Fabrication of Polarizer

The polymerization was carried out using a batch polymerization apparatus consisting of two longitudinal reactors with stirring blades and a reflux condenser controlled at 100 ° C. Bis [9- (2-phenoxycarbonylethyl) fluorene-9-yl] methane (Compound 3) 29.60 parts by mass (0.046 mol), ISB 29.21 parts by mass (0.200 mol), SPG 42.28 parts by mass (0.139 mol) And 63.77 parts by mass (0.298 mol) of DPC and 1.19 × 10 ⁻² parts by mass (6.78 × 10 ⁻⁵ mol) of calcium acetate monohydrate were added as a catalyst. After the inside of the reactor was purged with nitrogen under reduced pressure, heating was carried out with fruit, and stirring was started when the internal temperature reached 100 ° C. 40 minutes after the start of the temperature increase, the internal temperature was reached at 220 ° C., the pressure was controlled while maintaining the temperature, and the pressure was set to 13.3 Pa at 90 minutes after reaching 220 ° C. The by-product phenol vapor with the polymerization reaction was led to a reflux cooler at 100 ° C, the monomer component contained in a small amount in the phenol vapor was returned to the reactor, and the phenol vapor not condensed was led to a condenser at 45 ° C for recovery. Nitrogen was introduced into the first reactor and once back to atmospheric pressure, then the oligomerized reaction liquid in the first reactor was transferred to the second reactor. Next, the temperature increase and pressure reduction in a 2nd reactor were started, and it was internal temperature 240 degreeC, and the pressure of 0.2 kPa in 50 minutes. Then, polymerization was advanced until it became a predetermined stirring power. When the predetermined power was reached, nitrogen was introduced into the reactor and back-pressured, the resulting polyester carbonate was extruded in water, and the strands were cut to obtain pellets.

After vacuum-drying the obtained polycarbonate resin at 80 degreeC for 5 hours, a single screw extruder (Toshiba Machine Co., Ltd., cylinder set temperature: 250 degreeC), T-die (width 300mm, set temperature: 250 degreeC), chill roll (set temperature: 120-130 degreeC) and the polycarbonate resin film of thickness 135micrometer were produced using the film forming apparatus provided with the winding machine.

The stretched resin film was obtained by stretching the unstretched polycarbonate resin film using a stretching device. Preheating temperature was 145 degreeC and extending | stretching temperature was 138 degreeC. The draw ratio was 2.8 times. Re (550) of the resin film after extending | stretching was 140 nm.

The retardation film was obtained by immersing the resin film single side | surface after the said extending | stretching (immersion process) for 60 second in the liquid which methyl ethyl ketone and isopropyl alcohol mixed by 50:50 mass ratio. As a result of observing the surface of the retardation film with a scanning electron microscope, a wave shape along the direction orthogonal to the stretching axis was formed, and many pores were formed in the region of 4 탆 in the thickness direction on the surface.

Example 2

A retardation film was obtained in the same manner as in Example 1 except that the immersion time for the liquid was set to 90 seconds.

Example 3

A retardation film was obtained in the same manner as in Example 1 except that the immersion time for the liquid was 120 seconds.

Reference Example 1

The resin film after extending | stretching was used as a retardation film as it is, without immersion processing.

The retardation film of the Example was bonded together to the glass plate through the acrylic adhesive, and the sample for transmittance | permeability measurement was produced. Furthermore, the phase difference film of a reference example was bonded together to a glass plate through the light-diffusion adhesive prepared by mix | blending 9.5 parts of light-diffusion microparticles (Moment Tip Performance Co., Tospur 145, particle size 4.5 micrometer) with 100 parts of acrylic adhesives. , A sample for measuring transmittance was produced.

The sample for the said transmittance | permeability measurement was used for evaluation of said (1)-(2). The results are shown in Tables 1 to 3.

TABLE 1

TABLE 2

TABLE 3

As shown in Table 1, the retardation film of an Example has a haze value similar to the retardation film of the reference example which laminated | stacked the light-diffusion adhesive layer, and has high light-diffusion function, without forming another layer, such as a light-diffusion layer. there was. Moreover, it turns out that the retardation film of an Example has the haze value according to immersion processing time, and can obtain the retardation film which has a desired haze value by adjusting immersion processing time. In addition, as shown in Tables 1-3, in the retardation film of an Example, the transmittance | permeability of the light which inclines at the angle inclined along the direction parallel to a stretching axis is greater than the transmittance | permeability of the light which inclines at the inclination angle along the direction orthogonal to a stretching axis. Was small. Thus, the retardation film which has transmittance anisotropy can be used for the image display apparatus which has a bale view function.

The retardation film by embodiment of this invention is used suitably for an image display apparatus.

Claims (12)

Made of stretched resin film,
Retardation film with a haze value of 30% to 90%. The method of claim 1,
A retardation film having a light transmittance of wavelength 445 nm incident at a 50 ° incidence angle along a direction parallel to the stretching axis is smaller than a light transmittance of wavelength 445 nm incident at a 50 ° incident angle along a direction perpendicular to the stretching axis. The method of claim 1,
A retardation film having a wave shape along a direction perpendicular to the stretching axis. The method of claim 1,
A phase difference film, wherein the resin film is a polycarbonate resin film. The method of claim 1,
Retardation film whose said extending | stretching process is uniaxial stretching. The method of claim 1,
A retardation film having a void in a region of 4 µm in the thickness direction on at least one surface thereof. Equipped with a polarizing plate and a retardation layer,
The polarizing plate with retardation layer with which the said retardation layer is comprised by the retardation film of Claim 1. As a manufacturing method of the retardation film of Claim 1,
A method for producing a phase difference film comprising immersing the stretched resin film in a liquid containing a good solvent and a poor solvent for the resin film. The method of claim 8,
The immersion time of the said liquid film with respect to the said liquid film is 30 second-180 second. The method of claim 8,
The said resin film is a polycarbonate-type resin film, the said good solvent is ethyl acetate or methyl ethyl ketone, and the said poor solvent is isopropyl alcohol. The method of claim 8,
The mass ratio of the said good solvent and the said poor solvent in the said liquid is 45: 55-55: 45. The method of claim 8,
The manufacturing method further includes drying the immersed resin film.