KR20170034322A - Method for producing obliquely-stretched film - Google Patents

Abstract

A method for producing an obliquely stretched film comprises an oblique stretching step and a thermal fixing step. In the oblique stretching step, the transport direction of a film is reversed in an oblique stretching zone (Z2-2) to thereby stretch the film in an oblique direction with respect to the width direction. In the thermal fixing step, after termination of the oblique stretching step, a residual stress in the film due to the oblique stretching is relieved in a relief zone (Z3) in which the transport direction of the film is uniform. The oblique stretching zone (Z2-2) includes a first temperature distribution in which the temperature of the foregoing side is 1-15C lower than the temperature of the delayed side. The relief zone (Z3) includes a second temperature distribution in which the temperature of the foregoing side is 5-30C higher than the temperature of the delayed side. The temperature of the oblique stretching zone (Z2-2) is 5-40C higher than the temperature of the relief zone (Z3).

Description

METHOD FOR PRODUCING OBLIQUELY-STRETCHED FILM [0002]

The present invention relates to a method for producing a warp stretched film in which a film is stretched in an oblique direction with respect to a width direction.

2. Description of the Related Art Conventionally, self-emission type display devices such as organic EL (Electro-Luminescence) display devices also called OLED (Organic light-Emitting Diode) have attracted attention. In the OLED, since a reflector such as an aluminum plate is provided on the back side of the display in order to increase the light extraction efficiency, the external light incident on the display is reflected by the reflector, thereby lowering the contrast of the image.

Therefore, in order to improve the contrast of light and shade by preventing the reflection of external light, it is known that a circular polarizer is formed by joining a stretched film and a polarizer, and this circular polarizer is disposed on the surface side of the display. At this time, the circularly polarizing plate is formed by bonding a polarizer and a stretched film so that the in-plane slow axis in the stretched film is inclined at a desired angle with respect to the transmission axis of the polarizer.

However, a general polarizer (polarizing film) is obtained by stretching at a high magnification in the longitudinal direction, and its transmission axis coincides with the width direction. In addition, the conventional retardation film is produced by longitudinal drawing or transverse stretching, and in principle, the slow axis in the plane is at 0 DEG or 90 DEG with respect to the longitudinal direction of the film. Thus, in order to tilt the transmission axis of the polarizer and the slow axis of the stretched film to a desired angle as described above, it is not necessary to employ a batch formula in which the long polarizing film and / or the stretched film are cut at a specific angle and the film pieces are bonded one by one And productivity was deteriorating.

On the other hand, the film is stretched in the direction of the desired angle (in the oblique direction) with respect to the longitudinal direction, and the orientation of the slow axis is controlled by the long oblique stretching Various methods for producing a film have been proposed. For example, in the manufacturing method of Patent Document 1, the resin film is drawn out from a direction different from the winding direction of the film after stretching, and the both end portions of the resin film are gripped and transported by the pair of wave earths. By changing the conveying direction of the resin film in the middle, the resin film is stretched in the oblique direction. Thereby, a long obliquely-drawn film having a slow axis at a desired angle of more than 0 DEG and less than 90 DEG with respect to the longitudinal direction is produced.

By using such a long oblique stretched film, it is possible to produce a circular polarizer plate by joining a long polarizer film and a long obliquely stretched film by a roll-to-roll method, and the productivity of the circular polarizer plate is remarkably improved.

In the so-called bending type warp and stretch mechanism in which the direction of transporting the film is changed on the way, one of the pair of wave earths, which grips both ends of the film, relatively precedes and the other wave earth is relatively delayed do. That is, the pair of waveguides runs asymmetrically in the width direction of the film. As a result, the tension applied to the film becomes uneven in the width direction. Concretely, in the width direction of the film, the tensile force applied to the film is weaker than the side (retarded side) on which the wave earth travels in a delayed manner on the side where the wave earth travels ahead (the preceding side). As a result, in the film after the warp stretching, the film thickness becomes thick on the leading side, while the film thickness becomes thin on the delay side and the film thickness difference on the width side occurs.

Therefore, in the above-described Patent Document 1, a film is prepared in which the film thickness is changed in the width direction in advance, and this film is subjected to oblique stretching to try to make the film thickness uniform in the width direction after oblique stretching.

Japanese Patent Application Laid-Open No. 2010-173261 (Claim 1, paragraph [0006], [0010], Figures 1 to 4, etc.)

However, in the method of Patent Document 1, in order to obliquely draw, a film having a constant film thickness and a film having a film thickness varying in the width direction are produced separately, and oblique stretching is performed using a film having a varied film thickness There is a need. As described above, since it is necessary to prepare and prepare a film having a specifically changed film thickness, the productivity of the obliquely drawn film is deteriorated. In addition, if the stress imparted to the film by the warp stretching is not moderately relaxed, it is likely that ribs are wrinkled (rubbed) in the film due to the stress. Therefore, it is desired to realize a production method capable of improving the productivity of the warp stretched film while reducing occurrence of wrinkles.

An object of the present invention is to provide a method of manufacturing an oblique stretched film capable of improving the productivity while reducing the occurrence of wrinkles in the case of oblique stretching in which the carrying direction of the film is changed on the way .

The above object of the present invention is achieved by the following constitution. That is, in a method of producing an obliquely-drawn film according to an aspect of the present invention, both ends of the film in the width direction are gripped by a pair of gripping parts to transport the film, and in the warp stretching zone, Stretching the film in an oblique direction with respect to a width direction by relatively delaying one of the wave earth and relatively retarding the other wave earth,

Further comprising an alleviating step of alleviating the residual stress of the film by oblique stretching in a relaxation zone in which the film is conveyed in a constant direction after the oblique stretching step,

In the transverse direction of the film, when the side on which one of the pair of waveguide runs first in the oblique stretching is referred to as the leading side and the side in which the other is running in the retarded direction is referred to as the retarded side,

In the oblique stretching zone, a first temperature distribution is formed between the leading side and the retarding side in which the temperature on the preceding side is lower by 1 占 폚 to 15 占 폚 than the temperature on the retarding side,

Wherein the relaxation zone forms a second temperature distribution between the preceding side and the retarded side in which the temperature of the preceding side is higher by 5 占 폚 to 30 占 폚 than the temperature of the retarded side,

The temperature of the oblique stretching zone is 5 ° C to 40 ° C higher than the temperature of the relaxation zone.

According to the above-described production method, productivity of the film can be improved while decreasing the occurrence of wrinkles even when oblique stretching is performed by changing the transport direction of the film in the middle.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a plan view schematically showing a schematic configuration of an apparatus for producing an oblique drawn film according to an embodiment of the present invention. FIG.
2 is a plan view schematically showing an example of a rail pattern of a stretching portion of the manufacturing apparatus.
3 is an explanatory view schematically showing a temperature distribution from the delay side to the preceding side in the oblique stretching zone and the relaxation zone of the stretching portion.
4 is a graph showing an example of a temperature distribution (first temperature distribution) in the oblique stretching zone.
5 is a graph showing an example of a temperature distribution (second temperature distribution) in the relaxation zone.
6 is an explanatory diagram schematically showing a state in which heating sections are respectively arranged in the oblique stretching zone and the relieving zone.
Fig. 7 is an explanatory view schematically showing an example of the arrangement of the exhaust portion arranged in the stretching portion to form the second temperature distribution. Fig.
Fig. 8 is an explanatory view showing respective cross sections of the film after the warp stretching process and after the relaxation process.
Fig. 9 is a cross-sectional view showing a schematic configuration of an organic EL image display apparatus to which an obliquely stretched film produced by the production apparatus is applied. Fig.
10 is a cross-sectional view showing a schematic structure of a liquid crystal display device to which the oblique stretched film is applied.

An embodiment of the present invention will be described with reference to the drawings as follows. In the present specification, when numerical ranges A to B are represented, values of lower limit A and upper limit B are included in the numerical range.

A method of producing a long oblong stretched film (also referred to as a long oblong stretched film or simply an obliquely stretched film) according to the present embodiment is a method in which a long shaped raw film including a thermoplastic resin is sloped in the width direction and in the longitudinal direction Direction to prepare a long obliquely stretched film.

The orientation direction of the long obliquely-drawn film, that is, the direction of the slow axis, is a direction that makes an angle of more than 0 DEG and less than 90 DEG with respect to the width direction of the film (within a plane perpendicular to the thickness direction) With respect to the longitudinal direction of the film, an angle of more than 0 DEG and less than 90 DEG is obtained). Since the slow axis is usually expressed in the stretching direction or the direction perpendicular to the stretching direction, a long oblique stretched film having such slow axis can be produced by stretching the film in a direction of more than 0 DEG and less than 90 DEG with respect to the width direction of the film . The angle formed by the width direction of the long oblong stretched film and the slow axis, that is, the orientation angle can be arbitrarily set at a desired angle in a range of more than 0 DEG and less than 90 DEG.

In the present embodiment, the term "long" means that the film has a length of at least about 5 times or more, preferably 10 times or more, and more specifically, is rolled in a roll form to be stored or transported (Film roll) can be considered.

The long warp stretched film may be produced by winding a long unoriented film on a winding core to form a wound body (raw film), and supplying the raw film to the oblique stretching step from the wound body, The long film after the film formation may be supplied to the oblique stretching step continuously from the film forming step without taking up the long film. The film forming process and the oblique stretching process are successively performed because it is possible to change the film forming conditions by feeding back the results of film thickness and optical value of the film after stretching to obtain a desired long oblique stretched film. In addition, by continuously producing a long warp stretched film, a long warp stretched film having a desired length can be obtained.

As the thermoplastic resin contained in the fabric film, a cellulose ester resin, an alicyclic olefin polymer resin (COP), a polycarbonate resin (PC), or the like can be used.

The obliquely stretched film obtained by obliquely stretching the raw film can be applied to a liquid crystal display device which can be visually recognized by, for example, polarized sunglasses. That is, an oblique stretched film is bonded to the viewer side of the polarizer of the polarizing plate on the viewing side rather than the liquid crystal layer to constitute the circular polarizing plate. At this time, the both are bonded such that the slow axis of the obliquely drawn film and the transmission axis of the polarizer are 45 degrees. In this configuration, the linearly polarized light emitted from the liquid crystal layer and transmitted through the polarizer on the viewer side is converted into circularly polarized light from the obliquely drawn film (which functions as a? / 4 film). Therefore, when the viewer attaches the polarizing sunglasses and observes the display image of the liquid crystal display device, even if the angle between the transmission axis of the polarizer and the transmission axis of the polarizing sunglasses is parallel to the transmission axis of the polarizing sunglass, It is possible to guide the display image to the observer's eye. Therefore, it is possible to suppress the display image from being hardly seen in accordance with the viewing angle (along the transmission axis direction of the polarizing sunglasses).

Thus, when the obliquely stretched film is applied to the circularly polarizing plate of the liquid crystal display device corresponding to polarized sunglasses, it is preferable to form a hard coat layer for protecting the obverse-side stretched film on the obverse-side stretched film.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.

<Cellulose ester-based resin>

As the cellulose ester based resin film used in the raw film of the present embodiment, those containing a cellulose acylate satisfying the following formulas (1) and (2) and containing a compound represented by the following formula (A) .

2.0 < / RTI &gt; &lt; RTI ID =

(2) 0? X <3.0

(In the formulas (1) and (2), Z1 represents the total acyl substitution degree of the cellulose acylate, and X represents the sum of the propionyl substitution degree and the butyryl substitution degree of the cellulose acylate)

Hereinafter, the formula (A) will be described in detail. In formula (A), L ₁ and L ₂ each independently represent a single bond or a divalent linking group. Examples of L ₁ and L ₂ include the following structures (in the following, R represents a hydrogen atom or a substituent).

L ₁ and L ₂ are preferably -O-, -COO-, and -OCO-.

R ₁ , R ₂ and R ₃ each independently represent a substituent. Specific examples of the substituent represented by R ₁ , R ₂ and R ₃ include a halogen atom (fluorine atom, chlorine atom, bromine atom and iodine atom), an alkyl group (methyl group, ethyl group, n- Cyclohexyl group, cyclopentyl group, 4-n-dodecylhexyl group, etc.), alkenyl group (vinyl group, allyl group, etc.) (Such as a phenyl group, a p-tolyl group, or a naphthyl group), an alkenyl group (e.g., an isopropyl group, an n-butyl group, , A heterocyclic group (2-furyl group, 2-thienyl group, 2-pyrimidinyl group, 2-benzothiazolyl group and the like), cyano group, hydroxyl group, nitro group, carboxyl group, Butoxy group, 2-methoxyethoxy group, etc.), an aryloxy group (phenoxy group, 2-methylphenoxy group, 4-tert- Phenoxy group, 2- Acyloxy group, pivaloyloxy group, stearoyloxy group, benzoyloxy group, p-methoxyphenylcarbonyloxy group and the like), amino group (amino group , An acylamino group (formylamino group, acetylamino group, pivaloylamino group, lauroylamino group, benzoylamino group and the like), an amino group such as a methylamino group, a dimethylamino group, an anilino group, Alkyl and arylsulfonylamino groups such as methylsulfonylamino group, butylsulfonylamino group, phenylsulfonylamino group, 2,3,5-trichlorophenylsulfonylamino group and p-methylphenylsulfonylamino group, mercapto group, alkylthio group (Methylthio group, ethylthio group, n-hexadecylthio group and the like), arylthio group (phenylthio group, p-chlorophenylthio group and m-methoxyphenylthio group), sulfamoyl group Sulfamoyl group, N- (3-dodecyloxypropyl) sulfamoyl group, N, N- Methylsulfamoyl group, N-acetylsulfamoyl group, N-benzoyl sulfamoyl group and N- (N'-phenylcarbamoyl) sulfamoyl group), sulfo group, acyl group (acetyl group, pivaloylbenzoyl group Etc.), a carbamoyl group (carbamoyl group, N-methylcarbamoyl group, N, N-dimethylcarbamoyl group, N, N-di- Etc.).

R ₁ and R ₂ are preferably a substituted or unsubstituted phenyl group or a substituted or unsubstituted cyclohexyl group, more preferably a phenyl group having a substituent or a cyclohexyl group having a substituent, more preferably a substituent And a cyclohexyl group having a substituent at the 4-position.

R ₃ is preferably a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an aryl group, a heterocyclic group, a hydroxyl group, a carboxyl group, an alkoxy group, an aryloxy group, an acyloxy group, a cyano group or an amino group, Is a hydrogen atom, a halogen atom, an alkyl group, a cyano group, or an alkoxy group.

Wa and Wb represent a hydrogen atom or a substituent,

(I) Wa and Wb may combine with each other to form a ring,

(II) at least one of Wa and Wb may have a cyclic structure, or

(III) At least one of Wa and Wb may be an alkenyl group or an alkynyl group.

Specific examples of the substituent represented by Wa and Wb include a halogen atom (fluorine atom, chlorine atom, bromine atom and iodine atom), an alkyl group (methyl group, ethyl group, n-propyl group, isopropyl group, (Vinyl group, allyl group and the like), cycloalkenyl group (2-ethylhexyl group and the like), cycloalkyl group (cyclohexyl group, cyclopentyl group, (Such as a phenyl group, a p-tolyl group, or a naphthyl group), a heterocyclic group (such as a cyclopenten-1-yl group or a 2-cyclohexene-1-yl group), an alkynyl group (an ethynyl group or a propargyl group) A cyano group, a hydroxyl group, a nitro group, a carboxyl group, an alkoxy group (a methoxy group, an ethoxy group, an isopropoxy group, an isopropoxy group, an isopropoxy group, 2-methylphenoxy group, 4-tert-butylphenoxy group, 3-nitrophenoxy group, 2-methoxyphenoxy group, Tetradeca An aminophenoxy group and the like), an acyloxy group (formyloxy group, acetyloxy group, pivaloyloxy group, stearoyloxy group, benzoyloxy group and p-methoxyphenylcarbonyloxy group) An amino group, an amino group, a dimethylamino group, an anilino group, an N-methyl-anilino group and a diphenylamino group), an acylamino group (formylamino group, acetylamino group, pivaloylamino group, lauroylamino group and benzoylamino group) (Methylsulfonylamino group, butylsulfonylamino group, phenylsulfonylamino group, 2,3,5-trichlorophenylsulfonylamino group, p-methylphenylsulfonylamino group, etc.), mercapto group, alkylthio group (E.g., methylthio, ethylthio, n-hexyldecylthio etc.), arylthio groups (phenylthio group, p-chlorophenylthio group, m-methoxyphenylthio group etc.), sulfamoyl groups Di-, N- (3-dodecyloxypropyl) sulfamoyl group, N, N-dimethyl sulf (N-benzylsulfamoyl group, N- (N'-phenylcarbamoyl) sulfamoyl group and the like), sulfo group, acyl group (acetyl group, pivaloylbenzoyl group and the like) (Carbamoyl group, N-methylcarbamoyl group, N, N-dimethylcarbamoyl group, N, N-di-n-octylcarbamoyl group, N- (methylsulfonyl) carbamoyl group and the like) .

The substituent may be further substituted by the group.

(I) When Wa and Wb are bonded to each other to form a ring, the ring is preferably a nitrogen-containing 5-membered ring or a sulfur-containing 5-membered ring. The formula (A) is particularly preferably a compound represented by the following formula (1) or (2).

In formula (1), A ₁ and A ₂ each independently represent -O-, -S-, -NRx- (Rx represents a hydrogen atom or a substituent) or -CO-. Examples of the substituent represented by Rx are the same as the specific examples of the substituent represented by Wa and Wb. Rx is preferably a hydrogen atom, an alkyl group, an aryl group or a heterocyclic group.

In the formula (1), X represents a nonmetal atom of Groups 14 to 16. X is preferably = O, = S, = NRc, = C (Rd) Re. Herein, Rc, Rd and Re represent substituents, and examples thereof are the same as the specific examples of the substituents represented by Wa and Wb. _{L 1, L 2, R 1} , R 2, R 3, n , is _{L 1, L 2, R 1} , R 2, R 3, n and copper in the general formula (A).

In the formula (2), Q ₁ represents -O-, -S-, -NRy- (Ry represents a hydrogen atom or a substituent), -CRaRb- (wherein Ra and Rb represent a hydrogen atom or a substituent) -. Here, Ry, Ra and Rb represent a substituent, and examples thereof are the same as the specific examples of the substituent represented by Wa and Wb.

Y represents a substituent. Examples of the substituent represented by Y are the same as the specific examples of the substituent represented by Wa and Wb. Y is preferably an aryl group, a heterocyclic group, an alkenyl group or an alkynyl group.

Examples of the aryl group represented by Y include a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group and a biphenyl group, and a phenyl group and a naphthyl group are preferable, and a phenyl group is more preferable.

Examples of the heterocyclic group include a heterocyclic group containing at least one hetero atom such as a nitrogen atom, an oxygen atom, and a sulfur atom such as a furyl group, a pyrrolyl group, a thienyl group, a pyridinyl group, a thiazolyl group and a benzothiazolyl group , A furyl group, a pyrrolyl group, a thienyl group, a pyridinyl group, and a thiazolyl group are preferable.

These aryl groups or heterocyclic groups may have at least one substituent. Examples of the substituent include a halogen atom, an alkyl group having 1 to 6 carbon atoms, a cyano group, a nitro group, an alkylsulfinyl group having 1 to 6 carbon atoms, an alkylsulfonyl group having 1 to 6 carbon atoms, a carboxyl group, a fluoroalkyl group having 1 to 6 carbon atoms, An alkylthio group having 1 to 6 carbon atoms, an alkylthio group having 1 to 6 carbon atoms, an N-alkylamino group having 1 to 6 carbon atoms, an N, N-dialkylamino group having 2 to 12 carbon atoms, an N-alkylsulfamoyl group having 1 to 6 carbon atoms , An N, N-dialkylsulfamoyl group having 2 to 12 carbon atoms, and the like.

_{L 1, L 2, R 1} , R 2, R 3, n , is _{L 1, L 2, R 1} , R 2, R 3, n and copper in the general formula (A).

(II) Specific examples of the case where at least one of Wa and Wb in the formula (A) has a ring structure is preferably the following formula (3).

In the formula (3), Q ₃ represents ═N- or ═CRz- (Rz represents a hydrogen atom or a substituent), and Q ₄ represents a nonmetal atom of Groups 14 to 16. Z represents a group of nonmetal atoms forming a ring together with Q ₃ and Q ₄ .

The ring formed of Q ₃ , Q ₄ and Z may be further routed to another ring. The ring formed of Q ₃ , Q ₄ and Z is preferably a nitrogen-containing 5-membered ring or 6-membered ring condensed with a benzene ring.

_{L 1, L 2, R 1} , R 2, R 3, n , is _{L 1, L 2, R 1} , R 2, R 3, n and copper in the general formula (A).

(III) When at least one of Wa and Wb is an alkenyl group or an alkynyl group, they are preferably a vinyl group or an ethynyl group having a substituent.

Among the compounds represented by the above formulas (1), (2) and (3), the compounds represented by the formula (3) are particularly preferred.

The compound represented by the formula (3) is superior in heat resistance and light resistance to the compound represented by the formula (1), and has a solubility in an organic solvent and compatibility with a polymer Good.

The compound represented by the formula (A) may be contained in an appropriate amount to impart desired wavelength dispersibility and anti-smudge property. The amount of the compound represented by formula (A) is preferably 1 to 15% by mass relative to the cellulose derivative, By mass to 2% by mass to 10% by mass. Within this range, it is possible to impart sufficient wavelength dispersibility and anti-smudge property to the cellulose derivative.

The compound represented by the formula (A), the formula (1), the formula (2) and the formula (3) can be obtained by referring to a known method. Specifically, Journal of Chemical Crystallography (1997); 27 (9); 512-526, JP-A-2010-31223, JP-A-2008-107767, and the like.

(With respect to cellulose acylate)

The cellulose acylate film according to the present embodiment contains cellulose acylate as a main component. For example, the cellulose acylate film according to the present embodiment contains cellulose acylate in an amount of preferably 60 to 100 mass% with respect to the total mass (100 mass%) of the film. Further, the cellulose acylate has a total acyl group substitution degree of 2.0 or more and less than 3.0, more preferably 2.2 to 2.7.

Examples of the cellulose acylate include cellulose ester and an ester of an aliphatic carboxylic acid and / or aromatic carboxylic acid having about 2 to 22 carbon atoms, particularly an ester of cellulose and a lower fatty acid having 6 or less carbon atoms.

The acyl group bonded to the hydroxyl group of cellulose may be linear or branched or may form a ring. Further, a substituent may be substituted. When the number of carbon atoms is the same, the number of carbon atoms is preferably selected from an acyl group having from 2 to 6 carbon atoms, and the total sum of propionyl substitution degree and butyryl substitution degree is from 0 to less than 3.0 to be. The cellulose acylate preferably has 2 to 4 carbon atoms, more preferably 2 to 3 carbon atoms.

Concretely, examples of the cellulose acylate include acetyl groups such as cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate propionate butyrate or cellulose acetate phthalate, mixed fatty acids of cellulose having a propionate group, a butyrate group or a phthalyl group bonded thereto Esters can be used. The butyryl group forming the butyrate may be straight chain or branched.

In the present embodiment, cellulose acetate, cellulose acetate butyrate or cellulose acetate propionate is particularly preferably used as the cellulose acylate.

The cellulose acylate preferably satisfies the following formulas (i) and (ii) simultaneously.

(I) 2.0? X + Y < 3.0

(Ii) 0? X <3.0

Wherein Y represents the degree of substitution of the acetyl group and X represents the substitution degree of the propionyl group or the butyryl group or mixture thereof.

In addition, in order to obtain optical characteristics suitable for the purpose, resins having different degree of substitution may be mixed and used. The mixing ratio at that time is preferably 1:99 to 99: 1 (mass ratio).

Among the above-mentioned materials, cellulose acetate propionate is preferably used as the cellulose acylate. In cellulose acetate propionate, it is preferable that 0? Y? 2.5 and 0.5? X? 3.0 (however, 2.0? X + Y? 3.0), 0.5? Y? 2.0 and 1.0? However, it is more preferable that 2.0? X + Y < 3.0). The substitution degree of the acyl group can be measured in accordance with ASTM-D817-96, which is one of the standards formulated and issued by the American Society for Testing and Materials (ASTM).

The number average molecular weight of the cellulose acylate is preferably in the range of from 60000 to 300000 because the mechanical strength of the obtained film is increased. More preferably, a cellulose acylate having a number average molecular weight of 70,000 to 200,000 is used.

The weight average molecular weight (Mw) and the number average molecular weight (Mn) of the cellulose acylate are measured using gel permeation chromatography (GPC). The measurement conditions are as follows. The present measuring method can also be used as a method for measuring other polymers in the present embodiment.

Solvent: methylene chloride;

Column: Three shodex K806, K805 and K803G (manufactured by Showa Denko K.K.) are connected and used;

Column temperature: 25 캜;

Sample concentration: 0.1 mass%;

Detector: RI Model 504 (manufactured by GL Science);

Pump: L6000 (manufactured by Hitachi Seisakusho Co., Ltd.);

Flow rate: 1.0 ml / min

Calibration curve: Standard curve of polystyrene STK standard Polystyrene (manufactured by TOSOH CORPORATION) Mw = 1000000 to 500 Using a calibration curve of 13 samples. 13 samples are used at almost equal intervals.

The residual sulfuric acid content in the cellulose acylate is preferably in the range of 0.1 to 45 mass ppm in terms of sulfur element. They are thought to be contained in salt form. If the content of residual sulfuric acid exceeds 45 mass ppm, it tends to be easily broken at the time of thermal stretching or slitting after heat elongation. The residual sulfuric acid content is more preferably in the range of 1 to 30 mass ppm. The residual sulfuric acid content can be measured by the method specified in ASTM-D817-96.

The free acid content in the cellulose acylate is preferably 1 to 500 mass ppm. If it is in the above-mentioned range, it is preferable because it is hard to break as in the above. Further, the free acid content is preferably in the range of 1 to 100 mass ppm, and it is further difficult to break. And particularly preferably in the range of 1 to 70 mass ppm. The free acid content can be determined by the method specified in ASTM-D817-96.

The cellulose acylate thus synthesized is thoroughly washed, whereby the content of the residual sulfuric acid and the content of the free acid can be set within the above range, which is preferable.

Cellulose as a raw material of cellulose acylate is not particularly limited, but cotton linter, wood pulp, kenaf and the like can be mentioned. Further, the cellulose acylates obtained therefrom may be mixed and used in any ratio.

The cellulose acylate can be produced by a known method. Specifically, it can be synthesized with reference to the method described in, for example, Japanese Patent Application Laid-Open No. 10-45804.

The cellulose acylate is also influenced by the trace metal components in the cellulose acylate. These trace metal components are considered to be related to water used in the production process, but it is preferable that few components that can be insoluble nuclei are used. Particularly, metal ions such as iron, calcium, and magnesium may form insolubles by forming salts with polymer degradation products and the like, which may contain organic acid groups, and it is preferable that metal ions are less. In addition, the calcium (Ca) component can easily form an acidic component such as a carboxylic acid or a sulfonic acid and also many ligands and a coordination compound (i.e., a complex), and a scum (insoluble precipitate, turbidity) There is a risk of forming a low-melting point metal.

Specifically, the content of the iron (Fe) component in the cellulose acylate is preferably 1 mass ppm or less. The content of the calcium (Ca) component in the cellulose acylate is preferably 60 mass ppm or less, and more preferably 0 to 30 mass ppm. The content of the magnesium (Mg) component in the cellulose acylate is preferably 0 to 70 mass ppm, more preferably 0 to 20 mass ppm, because the content of the magnesium (Mg) component is insufficient.

The content of the metal component such as the content of the iron (Fe) component, the content of the calcium (Ca) component and the content of the magnesium (Mg) component can be controlled by adjusting the amount of the cellulose acylate, Nitric acid, pretreated by alkali melting, and then analyzed using an ICP-AES (inductively coupled plasma emission spectrochemical analyzer).

<Alicyclic Olefin Polymerization Resin>

Examples of the alicyclic olefin polymerization-type resin used in the raw film of the present embodiment include a cyclic olefin random multi-component copolymer disclosed in Japanese Patent Application Laid-Open No. 05-310845, A hydrogenated polymer, a thermoplastic dicyclopentadiene ring-opening polymer described in Japanese Patent Application Laid-Open No. 11-124429, a hydrogenated product thereof, and the like.

The alicyclic olefinic polymer resin is a polymer having an alicyclic structure such as a saturated alicyclic hydrocarbon (cycloalkane) structure or an unsaturated alicyclic hydrocarbon (cycloalkene) structure. The number of carbon atoms constituting the alicyclic structure is not particularly limited, but is usually in the range of 4 to 30, preferably 5 to 20, more preferably 5 to 15, and the mechanical strength, heat resistance, The formability properties are highly balanced and suitable.

The proportion of the repeating unit containing an alicyclic structure in the alicyclic olefin polymer may be appropriately selected, but is preferably 55% by weight or more, more preferably 70% by weight or more, and particularly preferably 90% by weight or more. When the proportion of the repeating unit having an alicyclic structure in the alicyclic polyolefin resin is within this range, the transparency and heat resistance of the optical material such as the retardation film obtained from the long oblong drawn film of the present embodiment are improved, which is preferable.

Examples of the olefin polymerization resin having an alicyclic structure include a norbornene resin, a monocyclic cycloolefin resin, a cyclic conjugated diene resin, a vinyl alicyclic hydrocarbon resin, and hydrides thereof. Among them, the norbornene resin can be suitably used because of its good transparency and moldability.

As the norbornene resin, for example, a ring-opening polymer of a monomer having a norbornene structure or a ring-opening copolymer of a monomer having a norbornene structure and another monomer or a hydride thereof, an addition polymer of a monomer having a norbornene structure, Addition copolymers of monomers having a norbornene structure and other monomers or hydrides thereof. Among them, a ring-opening (co) polymer hydride of a monomer having a norbornene structure can be suitably used particularly in view of transparency, moldability, heat resistance, low hygroscopicity, dimensional stability and light weight.

As a method for molding a long film (raw film) using the norbornene resin as described above, a solution casting method or a melt extrusion method is preferred. As the melt extrusion method, an inflation method using a die and the like can be mentioned, but a method using a T-die is preferable in that productivity and thickness precision are excellent.

As an extrusion molding method using a T die, a method of maintaining a molten thermoplastic resin in a stable state when it is brought into close contact with a cooling drum as described in Japanese Patent Application Laid-Open No. 2004-233604, It is possible to manufacture a long film having small variations in optical characteristics such as angle.

Specifically, 1) a method in which, when a long film is produced by a melt extrusion method, a sheet-like thermoplastic resin extruded from a die is brought into close contact with a cooling drum under a pressure of 50 kPa or less and is pulled; 2) a method in which, when a long film is produced by the melt extrusion method, the distance from the die opening to the cooling drum firstly brought into close contact with the surrounding member is set to 100 mm or less from the surrounding member to the die opening or the cooling drum to be first contacted; (3) a method of warming the temperature of the atmosphere within 10 mm from the sheet-form thermoplastic resin extruded from the die opening to a specific temperature when the long film is produced by the melt extrusion method; 4) a method in which a sheet-like thermoplastic resin extruded from a die is brought into close contact with a cooling drum under a pressure of 50 kPa or less to be pulled; (5) a method of blowing air having a speed difference of not more than 0.2 m / s from the drawing speed of a cooling drum which is first attached to a sheet-like thermoplastic resin extruded from a die opening when a long film is produced by a melt extrusion method have.

The long film may be a single layer or a laminated film of two or more layers. The laminated film can be obtained by a known method such as a coextrusion molding method, a shared softening molding method, a film lamination method, and a coating method. Of these, the co-extrusion molding method and the shared mold forming method are preferable.

<Polycarbonate-based resin>

As the polycarbonate resin used in the raw film of this embodiment, various resins can be used without particular limitation, and aromatic polycarbonate resins are preferable from the viewpoints of chemical properties and physical properties, and bisphenol A polycarbonates Nate resin is preferable. Among them, it is more preferable to use a bisphenol A derivative having a benzene ring, a cyclohexane ring and an aliphatic hydrocarbon group introduced into bisphenol A. Particularly preferred is a polycarbonate resin having a structure in which anisotropy in a unit molecule is reduced, obtained by using a derivative in which the functional group is introduced asymmetrically to the central carbon of bisphenol A. Examples of such polycarbonate resins include those obtained by substituting two methyl groups of the carbon at the center of bisphenol A with benzene rings, one hydrogen of each benzene ring of bisphenol A by asymmetric or phenyl groups, Is particularly preferably used.

Specifically, they are obtained from 4,4'-dihydroxydiphenylalkane or a halogen substituent thereof by a phosgene method or an ester exchange method, and examples thereof include 4,4'-dihydroxydiphenyl methane, 4,4 ' Dihydroxydiphenyl ethane, 4,4'-dihydroxydiphenyl butane, and the like. Further, for example, Japanese Patent Application Laid-Open Nos. 2006-215465, 2006-91836, 2005-121813, 2003-167121, and Japanese Patent Polycarbonate resins described in JP-A-2009-126128, JP-A-2012-31369, JP-A-2012-67300, and WO00 / 26705.

The polycarbonate resin may be used in combination with a transparent resin such as polystyrene type resin, methyl methacrylate type resin and cellulose acetate type resin. Further, a resin layer containing a polycarbonate resin may be laminated on at least one surface of a resin film formed using a cellulose acetate resin.

The polycarbonate resin preferably has a glass transition point (Tg) of 110 DEG C or more and a water absorption rate (value measured at 23 DEG C under water for 24 hours) of 0.3% or less. It is more preferable that the Tg is 120 ° C or more and the water absorption rate is 0.2% or less.

The polycarbonate resin film that can be used in the present embodiment can be formed by a known method, and among these, the solution casting method and the melt casting method are preferable.

<Additives>

The raw film of this embodiment may contain an additive. Examples of the additives include plasticizers, ultraviolet absorbers, retardation-adjusting agents, antioxidants, deterioration inhibitors, release aids, surfactants, dyes, and fine particles. In the present embodiment, additives other than the fine particles may be added at the time of preparing the dope liquid or may be added at the time of preparing the fine particle dispersion.

(Plasticizer)

Examples of the plasticizer to be added to the fabric film include phthalate ester, fatty acid ester, trimellitate ester, phosphate ester, polyester, sugar ester, and acrylic polymer. Among these, a plasticizer of a polyester-based or sugar ester-based polymer is preferably used from the viewpoint of moisture permeability.

The polyester-based plasticizer is superior to the phthalate ester-based plasticizer such as dioctyl phthalate in non-planarity and extrusion resistance. Depending on the application, these plasticizers may be selected or used in combination for a wide range of applications. As the acrylic polymer, homopolymers or copolymers of acrylic acid or alkyl methacrylate are preferable. Examples of the monomer of the acrylate ester include methyl acrylate, ethyl acrylate, propyl acrylate (i-, n-), butyl acrylate (n-, i-, s-, t-), pentyl acrylate (n-, i-), acrylonitrile (n-, i-), myristyl acrylate (n- , i-), acrylic acid (2-ethylhexyl), acrylic acid (? -caprolactone), acrylic acid (2-hydroxyethyl), acrylic acid (2-hydroxypropyl) Hydroxybutyl), acrylic acid (2-methoxyethyl), acrylic acid (2-ethoxyethyl) and the like, or the acrylic acid ester is replaced with methacrylic acid ester . The acrylic polymer is a homopolymer or copolymer of the above monomers, but preferably has 30 mass% or more of acrylic acid methyl ester monomer units and more preferably 40 mass% or more of methacrylic acid methyl ester monomer units. In particular, a homopolymer of methyl acrylate or methyl methacrylate is preferred.

The polyester plasticizer is a reaction product of a monovalent to tetravalent carboxylic acid and a monovalent to hexavalent alcohol, but mainly a product obtained by reacting a divalent carboxylic acid with a glycol is used. Representative divalent carboxylic acids include glutaric acid, itaconic acid, adipic acid, phthalic acid, azelaic acid, and sebacic acid. The polyester-based plasticizer is preferably an aromatic-terminal ester-based plasticizer. The aromatic terminal ester plasticizer is preferably an ester compound having a structure obtained by reacting phthalic acid, adipic acid, at least one benzene monocarboxylic acid, and at least one alkylene glycol having 2 to 12 carbon atoms. The structure of the final compound is not particularly limited as long as it has an adipic acid residue and a phthalic acid residue. When the ester compound is produced, it may be reacted as an acid anhydride or esterified product of a dicarboxylic acid.

Examples of the benzene monocarboxylic acid component include benzoic acid, para-tert-butylbenzoic acid, orthotoluenic acid, meta-toluic acid, paratoluic acid, dimethylbenzoic acid, ethylbenzoic acid, normal propylbenzoic acid, aminobenzoic acid, and acetoxybenzoic acid , And benzoic acid. These may be used alone or as a mixture of two or more kinds.

Examples of the alkylene glycol component having 2 to 12 carbon atoms include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, Propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 2,2- Propanediol (3,3-dimethylolheptane), 3-methyl-1,5-pentanediol, 1-n-butyl- Hexanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octanediol, 1,10-decanediol, 1,12-octadecanediol, and the like. Among these, 1,2-propylene glycol is particularly preferable. These glycols may be used alone or as a mixture of two or more thereof.

The aromatic terminal ester plasticizer may be any of oligoester and polyester, and the molecular weight is preferably in a range of from 100 to 10000, and more preferably in a range of from 350 to 3000. The acid value is not more than 1.5 mg KOH / g and the hydroxyl (hydroxyl value) is not more than 25 mg KOH / g, more preferably the acid value is not more than 0.5 mg KOH / g, and the hydroxyl (hydroxyl value) is not more than 15 mg KOH / g.

Specific examples thereof include, but are not limited to, the following compounds.

The sugar ester compound is an ester other than a cellulose ester and is a compound obtained by esterifying all or a part of the OH group of a sugar such as the following monosaccharides, 2 sugars, 3 sugars or oligosaccharides. More specific examples are compounds represented by the formula (4) And the like.

In the formulas, R ₁ to R ₈ represent a hydrogen atom, a substituted or unsubstituted alkylcarbonyl group having 2 to 22 carbon atoms, or a substituted or unsubstituted arylcarbonyl group having 2 to 22 carbon atoms. R ₁ to R ₈ may be the same or different.

Hereinafter, the compound represented by Formula (4) is more specifically shown (Compound 1-1 to Compound 1-23), but is not limited thereto. In the following table, when the average degree of substitution is less than 8.0, any one of R ₁ to R ₈ represents a hydrogen atom.

These plasticizers are preferably added in an amount of 0.5 to 30 parts by mass based on 100 parts by mass of the cellulose ester film.

(Retardation adjusting agent)

As a compound to be added for adjusting the retardation, an aromatic compound having two or more aromatic rings as described in European Patent No. 911,656A2 can be used.

Two or more kinds of aromatic compounds may be used in combination. It is particularly preferable that the aromatic ring of the aromatic compound contains an aromatic heterocycle in addition to an aromatic hydrocarbon ring. An aromatic heterocycle is generally an unsaturated heterocycle. Among them, 1,3,5-triazine ring is particularly preferable.

(Polymer or oligomer)

The textile film of the present embodiment is a polymer or oligomer of a vinyl compound having a cellulose ester and a substituent selected from a carboxyl group, a hydroxyl group, an amino group, an amide group and a sulfonic acid group and having a weight average molecular weight of 500 to 200,000 . The mass ratio of the content of the cellulose ester to the polymer or oligomer is preferably in the range of 95: 5 to 50:50.

(Made by Matt)

In the present embodiment, fine particles can be contained in the raw material film as a matting agent, thereby facilitating transport and winding of the raw material film and the long obliquely drawn film produced using the raw material film.

It is preferable that the particle size of the matting agent is primary particles or secondary particles of 10 nm to 0.1 占 퐉. A substantially spherical mat material having a needle aspect ratio of primary particles of 1.1 or less is preferably used.

As the fine particles, those containing silicon are preferable, and silicon dioxide is particularly preferable. Examples of the fine particles of silicon dioxide which are preferable in the present embodiment are Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50 and TT600 (manufactured by Nippon Aerosil Co., ), And aerosil 200V, R972, R972V, R974, R202 and R812 can be preferably used. Examples of the fine particles of the polymer include a silicone resin, a fluororesin and an acrylic resin. Silicone resin is preferable, and it is particularly preferable to have a three-dimensional network structure. Examples of such resins include Tospel 103, 105, 108, 120, 145, 3120 and 240 (manufactured by Toshiba Silicone Co., Ltd.).

The fine particles of silicon dioxide preferably have a primary average particle diameter of 20 nm or less and an apparent specific gravity of 70 g / L or more. More preferably, the primary particles have an average diameter of 5 to 16 nm, more preferably 5 to 12 nm. A smaller average primary particle diameter is preferable because of low haze. The apparent specific gravity is preferably 90 to 200 g / L or more, more preferably 100 to 200 g / L or more. The larger the apparent specific gravity is, the more desirable it is to make a high-concentration fine particle dispersion, and the haze and agglomerates do not occur.

The amount of the matting agent to be added in the present embodiment is preferably 0.01 to 1.0 g, more preferably 0.03 to 0.3 g, and still more preferably 0.08 to 0.16 g per 1 m ^{2 of the} fabric film.

(Other additives)

In addition, heat stabilizers such as kaolin, talc, diatomaceous earth, quartz, calcium carbonate, barium sulfate, titanium oxide and alumina, and salts of alkaline earth metals such as calcium and magnesium may be added. Surfactants, release promoters, antistatic agents, flame retardants, lubricants, and emulsions may also be added.

(Tension softening point)

The fabric film of this embodiment is required to be able to withstand use under a higher temperature environment. Therefore, the tensile softening point of the fabric film is preferably 105 ° C to 145 ° C because it exhibits sufficient heat resistance, and more preferably 110 ° C to 130 ° C.

As a specific measuring method of the tensile softening point, a sample film is cut to 120 mm (length) x 10 mm (width) using a tensile tester (RTC-1225A manufactured by ORIENTEC Co., Ltd.) / min and the temperature at the time when the temperature became 9 N was measured three times, and the average value was obtained.

(Dimensional change rate)

When the film after obliquely stretching the raw film of the present embodiment is applied to an organic EL image display apparatus, problems such as variations in thickness, a change in retardation value, and a reduction in contrast or color irregularity occur due to a dimensional change caused by moisture absorption , The dimensional change ratio (%) of the obliquely drawn film is preferably less than 0.5%, more preferably less than 0.3%.

(fault)

It is preferable that the raw material film of the present embodiment has few defects in the film. Here, the defect means defects such as voids (foaming defects) in the film caused by rapid evaporation of the solvent in the drying step of the solution film forming, foreign matters in the film forming solution and foreign matter (foreign matter defect) .

Concretely, it is preferable that defects having a diameter of 5 m or more in the film plane are 1 or less per square of 10 cm on one side. More preferably no more than 0.5 per square of 10 cm, and more preferably no more than 0.1 per square of 10 cm.

The diameter of the defect refers to the diameter when the defect has a circular shape, and when the defect is not circular, the range of the defect is determined by observing with a microscope by the following method, and the maximum diameter is defined as the diameter of the circumscribed circle.

The range of the defect is the size of the shadow when the defect is observed as the transmitted light of the differential interference microscope when the defect is bubble or foreign matter. When the defect is a change in surface shape such as a transfer of a roll scratch or a scratch, the size is confirmed by observing the defect as reflected light of a differential interference microscope.

In the case of observing with reflected light, if the size of the defect is unclear, aluminum or platinum is deposited on the surface and observed. In order to obtain a film having excellent durability exhibited by such defect frequency with high productivity, the polymer solution is filtered with high accuracy immediately before the pouring, the degree of cleanliness around the pore is raised, and the drying conditions after pouring are set stepwise, It is effective to suppress the foaming and dry it efficiently.

If the number of defects is more than one per square of 10 cm on one side, for example, if tension is applied to the film at the time of processing in a subsequent process, the film may be broken from the defect as a starting point and the productivity may be lowered. When the diameter of the defect is 5 mu m or more, it can be visually confirmed by observation of the polarizing plate or the like, and a bright spot may be generated when the defect is used as an optical member.

(Total light transmittance)

The raw film of the present embodiment preferably has a total light transmittance of 90% or more, more preferably 93% or more. The practical upper limit of the total light transmittance is about 99%. In order to attain excellent transparency expressed by the total light transmittance, it is necessary to prevent introduction of an additive or a copolymerizable component that absorbs visible light and to remove foreign matters in the polymer by high-precision filtration to reduce diffusion or absorption of light inside the film . In addition, it is possible to reduce the surface roughness of the film contacting portion (cooling roll, calender roll, drum, belt, coating liquid in the solution film formation, conveying roll, etc.) at the time of film formation to reduce the surface roughness of the film surface, Is effective.

&Lt; Method of forming a fabric film &

The raw film of the present embodiment containing the above-described resin can be formed by any of solution casting film forming method and melt casting film forming method described below. Here, the case where the raw material film contains a cellulose ester-based resin is explained, but the case where other raw materials are included is also the same.

When the fabric film is produced by the solution casting method, the dope, which is the raw material solution of the raw material film of the cellulose ester resin, is softened on the support including the rotating metal endless belt by the flexible die. The dope film formed on the support by the softening, that is, the web is peeled off by the peeling roll at about one week from the support. The peeled web (film) is then introduced into a stretching apparatus including a tenter.

In the extrusion method using a T-die, the polymer is melted at a melting temperature, extruded from a T-die into a film-like (sheet-like) type on a cooling drum, cooled and solidified, The film is peeled off. The peeled film is then introduced into a stretching apparatus including a tenter.

Hereinafter, the details of each film-forming method will be described.

[Solution flexible film-forming method]

In the method for producing a raw fabric film by the solution softening method, the solid concentration of the dope as the cellulose ester solution is usually about 10 to 40 mass%, and the dope viscosity in the softening step is in the range of 1 to 200 poise &Lt; / RTI &gt;

Here, first, the cellulose ester is dissolved by a means such as a stirring dissolving method, a heating dissolving method, an ultrasonic melting method and the like in a melting pot. Usually, the solvent is boiling above the boiling point of the solvent under normal pressure, , And dissolving with stirring is more preferable because it prevents the formation of a massive unsalted so-called gel or agglomerate. Also, the cooling dissolution method disclosed in Japanese Patent Application Laid-Open No. 9-95538 or the method disclosed in Japanese Patent Application Laid-Open No. 11-21379 may be used.

A method in which the cellulose ester is mixed with a poor solvent, followed by wetting or swelling, and further mixed with a two-component agent to dissolve is also preferably used. At this time, the apparatus for mixing cellulose ester with a poor solvent to wet or swell the apparatus and the apparatus for mixing and dissolving the two agents may be separately provided.

The kind of the pressurizing container used for dissolving the cellulose ester is not particularly limited, and it is only required to be able to withstand a predetermined pressure and to heat and stir under pressure. Instruments such as pressure gauges and thermometers are appropriately placed in the pressure vessel. The pressurization may be performed by a method of pressurizing an inert gas such as nitrogen gas or by raising the vapor pressure of the solvent by heating. The heating is preferably performed from the outside, and for example, a jacket type is preferable because temperature control is easy.

When the solvent is added, the heating temperature is not lower than the boiling point of the solvent to be used, and in the case of two or more mixed solvents, the temperature is raised to a temperature not lower than the boiling point of the lower boiling point solvent, . If the heating temperature is excessively high, the pressure required becomes large and the productivity becomes poor. The preferred range of the heating temperature is 20 to 120 캜, more preferably 30 to 100 캜, and still more preferably 40 to 80 캜. Further, the pressure is adjusted so that the solvent does not boil at the set temperature.

In addition to the cellulose ester and the solvent, additives such as a necessary plasticizer and ultraviolet absorber may be previously mixed with a solvent, dissolved or dispersed therein, and then added to a solvent before dissolution of the cellulose ester, or may be added to the dope after the dissolution of the cellulose ester.

After dissolving the cellulose ester, the cellulose ester may be taken out from the vessel while cooling or taken out from the vessel by a pump or the like, cooled in a heat exchanger or the like, and provided for film formation of the dope of the obtained cellulose ester.

When the mixture of the cellulose ester raw material and the solvent is dissolved in a dissolver having a stirrer, it is preferable that the peripheral velocity of the stirring blades is at least 0.5 m / sec or more, and the mixture is stirred for 30 minutes or more to dissolve.

The foreign matter contained in the cellulose ester dope (particularly foreign matter mistakenly recognized as an image in the liquid crystal display device) must be removed by filtration. The quality of the optical film may be determined by this filtration.

It is preferable that the filtration material used for filtration has a small absolute filtration accuracy. However, if the absolute filtration precision is too small, clogging of the filtration material tends to occur, and the filtration material must be frequently exchanged. Therefore, the filter material used for the cellulose ester dope preferably has an absolute filtration accuracy of 0.008 mm or less, more preferably 0.001 to 0.008 mm, and even more preferably 0.003 to 0.006 mm.

The material of the filter medium is not particularly limited and a usual filter medium can be used. However, a filter material made of plastic fibers such as polypropylene or Teflon (registered trademark), or a metal filter material made of stainless steel fiber or the like is preferable.

The filtration of the cellulose ester dope can be carried out by a conventional method. However, the method of filtration while heating under pressure at a temperature in the range that the boiling point of the solvent is not lower than the boiling point of the solvent at normal pressure, Pressure) may be small, which is preferable.

The preferred range of the filtration temperature is 45 to 120 캜, more preferably 45 to 70 캜, still more preferably 45 to 55 캜.

The filtration pressure is preferably 3500 kPa or less, more preferably 3000 kPa or less, and further preferably 2500 kPa or less. The filtration pressure can be controlled by appropriately selecting the filtration flow rate and the filtration area.

To prepare a cellulose ester based resin film, a cellulose ester solution (dope) is first prepared by dissolving a cellulose ester in a mixed solvent of a good solvent and a poor solvent, and adding the above plasticizer or ultraviolet absorber.

The dope can be flexible on the support at a temperature of the support in the range of generally 0 ° C to less than the boiling point of the solvent and further flexible on the support in the temperature range of 5 ° C to the solvent boiling point of -5 ° C, It is more preferable to be flexible on the support at a temperature range of 30 占 폚. At this time, it is necessary to control the surrounding atmosphere humidity to be equal to or higher than the dew point.

The dope adjusted so as to have a viscosity of 1 to 200 poises is so flexible as to have a substantially uniform film thickness from the flexible die onto the support and when the amount of residual solvent in the flexible film is greater than 200% (Web) is dried with the drying air so that the temperature of the flexible film is in the range of the solvent boiling point + 20 ° C or less until the amount of the residual solvent is 200% or less.

Here, the amount of the residual solvent can be represented by the following formula.

Amount of residual solvent (mass%) = {(M-N) / N} 100

In the formula, M is the weight of the web at any point in time, and N is the weight of the weight when dried at 110 ° C for 3 hours.

On the support, the amount of the residual solvent in the web is preferably dried to 150 mass% or less, more preferably 50 to 120 mass%, in order to dry and solidify the web until the film becomes peelable film strength from the support.

The web temperature at which the web is peeled from the support is preferably 0 to 30 占 폚. Further, since the temperature of the web rapidly lowers immediately after the peeling from the support, and the temperature of the web rapidly decreases due to the evaporation of the solvent from the side of the support adhered surface, and volatile components such as steam and solvent vapor in the atmosphere are likely to condense, More preferably from 5 캜 to 30 캜.

In the drying process of the web (or film), a method of drying while conveying the web by a roll suspension system, a pin tenter system or a clip tenter system is generally employed.

The web after peeling is introduced into, for example, a primary drying apparatus. In the primary drying apparatus, webs are conveyed serially by a plurality of conveying rollers staggered from the side, and the webs are blown from the ceiling of the drying apparatus, Lt; / RTI &gt;

Subsequently, the obtained film (sheet) is stretched in the uniaxial direction. The molecules are oriented by stretching. The stretching method is not particularly limited, but a known pin tenter or clip tenter can be preferably used. The stretching direction may be a longitudinal direction, a width direction, or any direction (oblique direction), but it is preferable that the stretching direction of the raw film is easily adjusted by making the stretching direction be the width direction.

In particular, in the drying step after peeling from the support, the web tends to shrink in the width direction by evaporation of the solvent. The higher the temperature, the greater the shrinkage. It is preferable to dry the film while suppressing the shrinkage as much as possible in terms of improving the planarity of the finished film. In view of this, for example, a method of drying the entire drying step or a part of the steps as described in Japanese Patent Application Laid-Open No. 62-46625 while keeping the both ends of the width of the web widthwise by a clip in the width direction (tenter method) desirable.

As the stretching condition of the raw material film, the temperature and the magnification can be selected so that the desired elongation at break characteristic can be obtained. Generally, the stretching ratio is 1.1 to 2.0 times, preferably 1.2 to 1.5 times, and the stretching temperature is usually from -40 占 폚 to Tg + 50 占 폚, preferably from Tg- Lt; RTI ID = 0.0 &gt; 40 C &lt; / RTI &gt; If the stretch ratio is too small, desired stretch elongation characteristics may not be obtained. On the contrary, if the stretch ratio is excessively large, breakage may occur. If the stretching temperature is excessively low, it is broken, and if it is excessively high, the desired stretch elongation characteristic may not be obtained.

In the case of modifying the breaking elongation property of the thermoplastic resin film produced by the above method to a desired characteristic suited to the purpose, the film may be stretched or shrunk in the longitudinal direction or the width direction. In order to contract in the longitudinal direction, for example, there is a method in which the film is shrunk by causing the width stretching to temporarily clip out and loosening in the longitudinal direction, or by gradually narrowing the interval between adjacent clips of the transverse stretching device. The latter method can be carried out by using a general simultaneous biaxial stretching device and moving the clip portion by a penta-graphical method or a linear drive method to smoothly narrow the distance between adjacent longitudinally extending clips .

The holding and stretching in the tenter may be carried out in any of the ranges from 50 to 150% by weight of the residual solvent immediately after being peeled, to substantially 0% by weight of the residual residual solvent immediately before winding, but the residual solvent amount is preferably in the range of 5 to 10% .

It is also often common to divide the tenter into several temperature zones in the running direction of the base. The temperature at which the desired physical properties and planarity are obtained is selected as the temperature at the time of stretching, but the temperature of the drying zone before and after the tenter may also be selected to be different from the temperature at the time of stretching for various reasons. For example, when the atmospheric temperature of the drying zone before the tenter is different from the temperature in the tenter, it is generally preferable to set the temperature of the zone near the inlet of the tenter to a temperature intermediate the temperature of the drying zone before the tenter and the temperature of the center of the tenter . Similarly, when the temperature in the tenter aftertenter is different, the temperature of the zone close to the tenter outlet is set to the intermediate temperature between the temperature in the tenter and the temperature in the tenter. The temperature of the drying zone before and after the tenter is generally 30 to 120 DEG C, preferably 50 to 100 DEG C, the temperature of the drawing portion in the tenter is 50 to 180 DEG C, preferably 80 to 170 DEG C, The temperatures of the parts are appropriately selected from their intermediate temperatures.

The pattern of the stretching, that is, the trajectory of the gripping clip is selected from the optical properties and planarity of the film as in the case of the temperature, and is varied, but is a constant width for a short time after the start of grinding and is then stretched, Patterns are often used. In the vicinity of the end of the clip grip near the tenter outlet, width reduction is generally performed in order to suppress the base vibration due to opening of the grip.

The drawing pattern is also related to the drawing speed, but the drawing speed is generally 10 to 1000 (% / min), preferably 100 to 500 (% / min). This stretching speed is not constant when the clip trajectory is a curve, but gradually changes in the running direction of the base.

Further, the web (film) after drying by the tenter system is continuously introduced into the secondary drying apparatus. In the secondary drying apparatus, the web is conveyed serially by a plurality of conveying rolls staggered from the side, the web is blown from the ceiling of the secondary drying apparatus, And is wound around a winder as a raw film of a cellulose ester resin.

The means for drying the web is not particularly limited, and hot air, infrared rays, heating rolls, microwaves, etc. are generally used. In terms of convenience, it is preferable to dry with hot air. The drying temperature is preferably 40 to 150 占 폚, and more preferably 80 to 130 占 폚 because planarity and dimensional stability are improved.

As described above, in the web drying step, the web peeled from the support is further dried, and finally the amount of the residual solvent is adjusted to 3 mass% or less, preferably 1 mass% or less, more preferably 0.5 mass% or less , And is preferable in terms of obtaining a film having good dimensional stability.

The process from softening to post-drying may be performed in an air atmosphere, or in an inert gas atmosphere such as nitrogen gas. In this case, it goes without saying that the drying atmosphere is carried out in consideration of the explosive limit concentration of the solvent.

Further, embossing is carried out on both side edges of the cellulose ester resin-finished resin film of the cellulose ester-based resin after completion of the conveying and drying step by the embossing device in the stage before introduction into the winding step It is preferable to perform processing. As the embossing processing apparatus, for example, an apparatus described in Japanese Patent Application Laid-Open No. 63-74850 can be used.

The winding machine relating to the production of the cellulose ester resin-based raw material film can be wound by a winding method such as a normal tension method, a constant torque method, a taper tension method and a program tension control method with a constant internal stress .

Though the film thickness of the raw fabric film after winding is different depending on the purpose of use, the film thickness range is 20 to 200 mu m, and in recent thin tendency, it is preferably in the range of 30 to 120 mu m, more preferably in the range of 40 to 100 mu m desirable.

[Melting flexible film-forming method]

Examples of the melt soft-film-forming method include a melt-extrusion method such as a method using a T-die or an inflation method, a calendering method, a hot pressing method, and an injection molding method. Among them, a method using a T-die, which is small in thickness unevenness, easy to be processed to a thickness of about 50 to 500 탆, and capable of reducing unevenness in film thickness and unevenness of retardation, is preferable. The extrusion method using a T die is a method in which a polymer is melted at a melting temperature and extruded from a T die onto a cooling drum in the form of a film (sheet), cooled and solidified, and peeled off from the cooling drum. And can be preferably used.

The melt extrusion can be carried out under the same conditions as those used for other thermoplastic resins such as polyester. For example, the cellulose ester which has been dried under a hot air or a vacuum or a reduced pressure is melted at an extrusion temperature of about 200 to 300 ° C by using a uniaxial or biaxial extruder, filtered with a filter of a leaf disc type, , Flexible from a T-die to a film (sheet), and solidified on a cooling drum. When introduced into the extruder from the feed hopper, it is preferable to prevent the oxidative decomposition or the like under a reduced pressure or an inert gas atmosphere.

The extrusion flow rate is preferably stabilized by introducing a gear pump. In addition, a stainless steel fiber sintered filter is preferably used as a filter used for removing foreign matters. The stainless steel fiber sintering filter is made by integrating a stainless steel fiber body into a state in which the fibers are intricately intertwined with each other, compressing them and sintering the contact points, and adjusting the filtration accuracy by changing the density according to the thickness and the amount of compression. It is preferable that the filtration precision is a multilayer body obtained by continuously repeating a plurality of times in a coarse and dense manner. In addition, it is preferable to take a configuration in which the filtration accuracy is sequentially increased, or to adjust the filtration accuracy and to repeat the milling, so that the filtration life of the filter is prolonged and the replenishment accuracy of foreign matters and gels can be improved .

When scratches or foreign matter adhere to the die, a stripe-like defect may occur. Such a defect is called a die line. In order to reduce defects on the surface of a die line or the like, it is preferable that the pipe from the extruder to the die has a structure in which the retention portion of the resin is minimized. In addition, it is preferable to use the die without any scratches or the like on the inside or the lip of the die. A volatile component is precipitated from the resin around the die to cause die lines. Therefore, it is preferable to suck the atmosphere containing the volatile component. In addition, since it may precipitate in an apparatus such as an electrostatic attraction, it is preferable to apply alternating current or prevent precipitation by another heating means.

Additives such as plasticizers may be mixed with the resin in advance, or may be put in the middle of the extruder. To uniformly add, it is preferable to use a mixing device such as a static mixer.

The temperature of the cooling drum is preferably not higher than the glass transition temperature of the thermoplastic resin. It is preferable to use a method in which the resin is brought into close contact with the cooling drum by electrostatic force, a method in which the resin is brought into close contact with wind pressure, a method in which the resin is brought into close contact with the entire width or end,

Unlike the raw film formed by the solution casting method, the raw film of the thermoplastic resin molded by the melt softening method has a feature that the retardation in the thickness direction (Rt) is small and the stretching condition different from the solution casting film forming method Sometimes it becomes necessary. In some cases, stretching in the film advancing direction and stretching in the film width direction may be performed simultaneously or sequentially to obtain desired optical properties. In some cases, the film may be stretched only in the film width direction. The molecules are oriented by this stretching operation, and the film is adjusted to a necessary retardation value.

When the raw fabric film of the present embodiment is produced by the melt softening process, substantially the same ultraviolet absorbers as those used in the method for producing a raw fabric film by the solution casting process can be used.

The blending amount of these ultraviolet absorbers is preferably 0.01 to 10% by mass, more preferably 0.1 to 5% by mass, based on the thermoplastic resin. If the amount is too small, the ultraviolet ray absorbing effect may be insufficient. On the other hand, if the amount is too large, the transparency of the film may deteriorate. The ultraviolet absorber preferably has high thermal stability.

It is preferable to add fine particles to the fabric film in order to impart the slidability of the film. As the fine particles to be used, any of inorganic compounds or organic compounds may be used if it has heat resistance at the time of melting. Examples of the inorganic compound include silicon compounds, silicon dioxide, aluminum oxide, zirconium oxide, calcium carbonate, talc, Calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate and calcium phosphate are preferable, and an inorganic compound containing zirconium or zirconium oxide is more preferable. Among them, silicon dioxide is particularly preferably used in that the haze can be suppressed small. Even when the fabric film is produced by the melt soft-film formation method, substantially the same materials as those used in the production method of the raw film by the solution casting method can be used as the matting agent to be used.

<Specification of fabric film>

The thickness of the raw film in this embodiment is preferably 1 to 400 占 퐉, preferably 20 to 200 占 퐉, more preferably 30 to 120 占 퐉, particularly preferably 40 to 100 占 퐉.

The width of the fabric film is not particularly limited, but may be 500 to 4000 mm, preferably 1000 to 2000 mm.

The preferable elastic modulus at the stretching temperature at the time of warp stretching of the fabric film is 0.01 MPa or more and 5000 MPa or less, more preferably 0.1 MPa or more and 500 MPa or less, When the modulus of elasticity is too low, the shrinkage rate after stretching and stretching is lowered, and wrinkles are less likely to disappear. When the modulus of elasticity is excessively high, the tensile force at the time of stretching becomes large, and it is necessary to increase the strength of the portion that keeps both side edges of the film, and the load on the tenter in the subsequent process increases.

As the raw material film, there may be used a non-oriented film or a film having a predetermined orientation. Further, if necessary, the distribution in the width direction of the orientation of the raw film may be arcuate, so-called bowing. The orientation of the raw film can be adjusted so that the orientation of the film at the position where the drawing of the subsequent process is completed is desired.

&Lt; Method of manufacturing oblique stretched film &

Next, a description will be given of a method and a device for producing an obliquely-drawn film in which the long film is stretched in an oblique direction with respect to the width direction to produce a long obliquely stretched film.

(Overview of the device)

1 is a plan view schematically showing a schematic configuration of an apparatus 1 for producing an obliquely-drawn film. The manufacturing apparatus 1 includes a film feed portion 2, a conveying direction changing portion 3, a guide roll 4, a stretching portion 5, and a guide 5 in this order from the upstream side in the conveying direction of the long film, A roll 6, a transport direction changing portion 7, and a film winding portion 8. [ A film cutting device may be provided between the transport direction changing portion 7 and the film winding portion 8 to cut the film after the warp stretching to a desired length and wind it around the film winding portion 8. Details of the stretching portion 5 will be described later.

The film feeding portion 2 feeds the long film described above to the stretching portion 5. The film feed portion 2 may be formed separately from the film forming apparatus of the long film, or may be integrally formed. In the case of the former, a long film is fed from the film feeding portion 2 by winding the long film on the winding core once and winding the film from the winding body (long film fabric) onto the film feeding portion 2. On the other hand, in the latter case, after film formation of the long film, the film feed portion 2 is fed to the stretching portion 5 without winding the long film.

The transport direction changing section 3 changes the transport direction of the long film fed out from the film feed section 2 to the direction toward the entrance of the stretching section 5 as the warp stretching tent. The carrying direction changing section 3 includes, for example, a turn bar for changing the carrying direction by folding while conveying the film, and a rotary table for rotating the turn bar in a plane parallel to the film.

By changing the conveying direction of the long film in the conveying direction changing section 3 as described above, the width of the entire manufacturing apparatus 1 can be made narrower, and furthermore, the conveying position and angle of the film can be finely controlled And it becomes possible to obtain a warp stretched film having a small variation in film thickness and optical value. When the film feeding portion 2 and the conveying direction changing portion 3 are movable (slidable and pivotable), the stretching portion 5 is provided with the right and left clips It is possible to effectively prevent the badness of the film against the film.

The film feed portion 2 may be slidable and pivotable so as to feed a long film at a predetermined angle to the entrance of the stretching portion 5. In this case, it is also possible to adopt a configuration in which the installation of the transport direction changing section 3 is omitted.

At least one guide roll 4 is provided on the upstream side of the stretching portion 5 in order to stabilize the trajectory of the long film during traveling. The guide roll 4 may be constituted by a pair of upper and lower pairs of rolls, or a plurality of pairs of rolls. The guide roll 4 closest to the entrance of the stretching portion 5 is a driven roll for guiding the running of the film and is rotatably supported by a bearing portion (not shown). As the material of the guide roll 4, known rollers can be used. In order to prevent the occurrence of scratches on the film, it is preferable to reduce the weight of the guide roll 4 by applying a ceramic coating to the surface of the guide roll 4, or chrome plating the light metal such as aluminum.

It is preferable that one of the rolls on the upstream side of the guide roll 4 closest to the entrance of the stretching portion 5 is nipped by pressing the rubber roll. By using such a nip roll, it is possible to suppress fluctuation of the feeding tension in the film flow direction.

A pair of bearing portions at both ends (right and left) of the guide roll 4 closest to the entrance of the stretching portion 5 are provided with a film tension detecting device for detecting a tension generated in the film in the roll, Device, and a second tension detector are provided, respectively. As the film tension detecting device, for example, a load cell can be used. As the load cell, a known type of tensile or compression type can be used. The load cell is a device that converts a load acting on a point of attachment into an electric signal by a strain gauge provided on the base body and detects it.

The load cell is provided on the right and left bearing portions of the guide roll 4 closest to the entrance of the stretching section 5 so that the force exerted by the film during running on the roll, The tension is detected independently in the left and right direction. Further, a strain gauge may be provided directly on a support constituting the bearing portion of the roll, and the load, that is, the film tension may be detected based on the strain generated in the support. The relationship between the generated strain and the film tension is measured in advance and is assumed to be known.

When the position and transport direction of the film supplied from the film feed portion 2 or the transport direction changing portion 3 to the stretching portion 5 are shifted from the position toward the entrance of the stretching portion 5 and the transport direction, A difference occurs in the tension in the vicinities of both side edges of the film in the guide roll 4 closest to the entrance of the stretching section 5 depending on the displacement amount. Therefore, by detecting the tension difference by installing the film tension detecting device as described above, it is possible to determine the degree of the deviation. That is, the load acting on the guide roll 4 becomes substantially equal at both ends in the axial direction when the conveying position and the conveying direction of the film are appropriate (the position and direction toward the inlet of the stretching section 5) Otherwise, difference in film tension occurs between right and left.

Therefore, for example, the transport direction changing section 3 changes the film position and the transport direction (the transport direction of the stretching section (the film stretching section)) so that the film tension difference between the left and right sides of the guide roll 4 closest to the entrance of the stretching section 5 becomes equal. 5) is appropriately adjusted, the grasping of the film due to the waveguide of the entrance portion of the stretching portion 5 is stabilized, and the occurrence of the obstacle such as the waveguide deviation can be reduced. Further, the physical properties of the film in the width direction after the oblique stretching by the stretching portion 5 can be stabilized.

At least one guide roll 6 is provided on the downstream side of the stretching portion 5 in order to stabilize the trajectory at the time of running of the obliquely stretched film in the stretching portion 5.

The carrying direction changing portion 7 changes the carrying direction of the film after being drawn from the stretching portion 5 in the direction toward the film winding portion 8.

Here, the film advancing direction at the entrance of the stretching section 5 and the film advancing direction at the exit of the elongating section 5 are set so as to correspond to the fine adjustment of the orientation angle (direction of the slow axis in the plane of the film) It is necessary to adjust the angle. In order to adjust the angle, it is preferable to change the advancing direction of the formed film by the conveying direction changing portion 3 to guide the film to the entrance of the stretching portion 5 and / It is necessary to change the traveling direction of the film by the carrying direction changing portion 7 to return the film to the film winding portion 8 direction.

In addition, it is preferable to continuously perform film formation and warp stretching in terms of productivity and yield. When the film forming process, the warp stretching process, and the winding process are continuously performed, the film advancing direction is changed by the carrying direction changing portion 3 and / or the carrying direction changing portion 7, As shown in Fig. 1, the moving direction of the film fed from the film feeding portion 2 and the moving direction of the film immediately before being wound by the film winding portion 8 Winding direction), it is possible to reduce the width of the entire device with respect to the film advancing direction.

It is not necessary that the film advancing direction in the film forming process and the winding process necessarily coincides with each other. However, in order to obtain a layout in which the film feeding portion 2 and the film winding portion 8 do not interfere, the feeding direction changing portion 3 and / Or the carrying direction changing portion 7 to change the traveling direction of the film.

The above-described transport direction changing units 3 and 7 can be realized by a known method such as using an air flow roll or an air turn bar.

The film take-up unit 8 is for winding a film conveyed from the stretching unit 5 through the conveying direction changing unit 7 and is constituted by, for example, a winder device, an algebraic device, a drive device or the like. It is preferable that the film take-up unit 8 is a structure that can slide in the lateral direction so as to adjust the winding position of the film.

The film take-up portion 8 is capable of finely controlling the take-in position and angle of the film so that the film can be pulled at a predetermined angle with respect to the exit of the stretching portion 5. [ This makes it possible to obtain a long oblong stretched film having a small variation in film thickness and optical value. Further, the occurrence of wrinkles of the film can be effectively prevented, and the winding-up property of the film is improved, so that it becomes possible to take up the film in a long length.

The film winding portion 8 constitutes a pulling portion for pulling the film stretched and conveyed by the stretching portion 5 with a predetermined tension. Between the stretching portion 5 and the film take-up portion 8, a take-up roll for pulling the film at a constant tension may be provided. The guide roll 6 described above may have a function as the take-up roll.

In the present embodiment, the pulling tension T (N / m) of the stretched film is preferably adjusted within a range of 100 N / m <T <300 N / m, preferably 150 N / m <T <250 N / m . If the pulling tension is 100 N / m or less, loosening or wrinkling of the film tends to occur, and the profile of the retardation and orientation angle in the film width direction is also deteriorated. On the other hand, when the pulling tension is 300 N / m or more, the variation of the orientation angle in the film width direction is deteriorated and the width yield (picking efficiency in the width direction) is deteriorated.

In the present embodiment, it is preferable to control the fluctuation of the take-up tension T at an accuracy of less than ± 5%, preferably less than ± 3%. If the variation of the take-up tension T is ± 5% or more, fluctuations in the optical characteristics in the width direction and the flow direction (transport direction) become large. As a method of controlling the fluctuation of the take-up tension T within the above range, the load applied to the first roll (guide roll 6) on the exit side of the stretching portion 5, that is, the tensile force of the film is measured, And the rotational speed of the take-up roll of the take-up roll or film take-up unit 8 is controlled by a general PID control method so as to be constant. As a method for measuring the load, there is a method in which a load cell is provided on the bearing portion of the guide roll 6 and the load applied to the guide roll 6, that is, the tensile force of the film is measured. As the load cell, a known type of tensile type or compression type can be used.

After stretching, the film is released from the outlet of the stretching section 5 by the gripping of the stretching section 5, and both ends (both sides) of the film held by the gripping section are trimmed, And wound around a core (winding roll) to form a winding body of a long warp stretched film. The trimming may be performed as necessary.

Further, before winding the long oblong stretched film, for the purpose of preventing blocking between the films, the masking film may be superposed and wound on the long oblong stretched film at the same time, or at least one of the long oblong stretched films Tape or the like may be wound while being joined to the ends of both ends). The masking film is not particularly limited as long as it can protect the long warp stretched film. Examples of the masking film include a polyethylene terephthalate film, a polyethylene film, and a polypropylene film.

Further, before winding the long warp stretched film, at both ends in the width direction of at least one surface (preferably both surfaces) of the film, a thickened portion (convex portion) called a burring portion or an embossing portion So that blocking of the films when the film is wound may be prevented. Further, the height and shape of the knurled portion may be different at both end portions in the width direction (may be asymmetrical).

(Details of extension section)

Next, the elongating unit 5 will be described in detail. Fig. 2 is a plan view schematically showing an example of the rail pattern of the extending portion 5. Fig. However, this is merely an example, and the configuration of the extending portion 5 is not limited to this.

The long oblong stretched film in the present embodiment is produced by using a tenter stretchable tenter (warp stretching machine) as the stretching portion 5. This tenter is a device for heating a long film to an arbitrary stretchable temperature and obliquely stretching it. This tenter is constituted by a heating zone Z and a pair of right and left rails Ri and Ro and a plurality of wave cores Ci and Co running along the rails Ri and Ro to transport the film Only one gripping region is shown). Details of the heating zone Z will be described later. The rails Ri and Ro each have a plurality of rail portions connected to each other through a connecting portion (white circles in Fig. 2 are examples of connecting portions). The waveguides (Ci, Co) are constituted by clips holding both ends in the width direction of the film.

2, the elongation direction D1 of the long film is different from the elongation direction D2 of the elongated oblong stretched film after elongation, and forms the elongation angle? I between the elongation direction D1 and the winding direction D2. The feeding angle? I can be arbitrarily set to a desired angle in a range of more than 0 ° and less than 90 °.

Since the feeding direction D1 and the winding direction D2 are different from each other in this way, the rail pattern of the tenter is asymmetrical in the right and left direction, and the conveying path of the film is bent in the middle. Further, the rail pattern can be manually or automatically adjusted in accordance with the orientation angle [theta] and the stretch magnification which are provided for the long obliquely drawn film to be produced. In the warp stretching machine used in the manufacturing method of the present embodiment, it is preferable that the positions of the rail portions and the rail connecting portions constituting the rails Ri and Ro are freely set and the rail pattern can be arbitrarily changed.

In the present embodiment, the plurality of tappets (Ci, Co) of the tenter are arranged to be spaced apart from the front and rear tappets (Ci, Co) and run at a constant speed. The traveling speed of the wave earth (Ci, Co) can be appropriately selected, but is usually 1 to 150 m / min. In the present embodiment, in consideration of the productivity of the film, it is preferably 20 to 100 m / min. The difference in traveling speed between the pair of left and right wave earths (Ci, Co) is usually 1% or less, preferably 0.5% or less, more preferably 0.1% or less of the traveling speed. This is because it is required that the speed difference between the left and right wave cores Ci and Co is substantially the same speed because there is a wrinkle and a warp at the exit of the drawing process if there is a difference in the traveling speed of the film from left to right at the exit of the drawing process to be. In a general tentering machine or the like, there is a speed variation occurring on the order of seconds or less depending on the sawing period of the sprocket for driving the chain, the frequency of the drive motor, etc. and often causes a few percent unevenness. It does not apply to speed difference.

In the warp stretcher used in the production method of the present embodiment, a rail for regulating the trajectory of the crushing strip is often required to have a large bending rate, particularly at a point where the conveyance of the film becomes oblique. In order to avoid interference between waveguides due to abrupt bending, or local concentration of stress, it is desirable to make the locus of the waveguide curved at the bent portion.

As described above, the oblique stretching tenters used for imparting the long film orientation in the oblique direction can freely set the orientation angle of the film by variously changing the rail pattern, and the orientation axis (slow axis) It is preferable that the film is a tenter which can be uniformly aligned with high accuracy across the width direction and can control film thickness and retardation with high precision.

Next, the drawing operation in the stretching section 5 will be described. Both ends of the long film are gripped by the left and right wave plates Ci and Co and are transported in the heating zone Z in accordance with traveling of the wave plates Ci and Co. The left and right waveguides Ci and Co are opposed to each other in a direction substantially perpendicular to the advancing direction of the film (the feeding direction D1) at the entrance portion (position A in the drawing) of the stretching portion 5 (Left and right asymmetric rails Ri and Ro), and the film gripped at the exit portion (position B in the drawing) at the end of drawing is opened. The film released from the wave zones (Ci, Co) is wound on the winding core in the film winding section 8 described above. The pair of rails Ri and Ro each have an endless continuous trajectory and the wave cores Ci and Co that open the gripping of the film at the outlet of the tenter are driven by the outer rails, To be returned to the original position.

In this case, since the rails Ri and Ro are asymmetric, the left and right waveguides Ci and Co opposed to each other at the position A in FIG. 2 travel on the rails Ri and Ro Accordingly, the waveguide Ci running on the rail Ri side (in the course side) becomes the positional relationship preceding the waveguide Co running on the rail Ro side (outcourse side).

In other words, of the waveguides (Ci, Co) which were opposed in the direction substantially perpendicular to the film feeding direction D1 at the position of A in the drawing, one waveguide Ci was positioned at the position , The straight line connecting the waveguides Ci and Co is inclined by an angle? L with respect to a direction substantially perpendicular to the winding direction D2 of the film. By this cauterization, the long film is obliquely stretched at an angle of? L with respect to the width direction. Here, the term &quot; substantially perpendicular &quot;

Next, details of the heating zone Z will be described. The heating zone Z of the stretching section 5 is constituted by a preheating zone Z1, a stretching zone Z2 and a relaxation zone Z3. In the stretching section 5, the film held by the waveguides Ci and Co sequentially passes through the preheating zone Z1, the stretching zone Z2, and the relaxation zone Z3. In the present embodiment, the preheating zone Z1 and the stretching zone Z2 are partitioned by partition walls, and the stretch zone Z2 and mitigation zone Z3 are partitioned by partition walls. Also, a partition wall may be appropriately provided in each zone of the preheating zone Z1, the stretching zone Z2, and the relaxation zone Z3 (the inside of each zone may be further divided as a partition).

The preheating zone Z1 is a zone in which the wave cores Ci and Co holding both ends of the film in the inlet portion of the heating zone Z travels with left and right (in the film width direction) to be.

The stretching zone Z2 is a zone from when the interval between the waveguides Ci and Co holding the both ends of the film starts to increase and reaches a predetermined interval. At this time, oblique stretching is performed as described above, but it may be stretched in the longitudinal direction or in the transverse direction before and after oblique stretching, if necessary. Fig. 2 shows an example in which the stretching zone Z2 includes a transverse stretching zone Z2-1 and an oblique stretch zone Z2-2 along the film transport direction. In the transverse stretching zone Z2-1, the film is stretched in the width direction (transverse direction) by widening the interval between the pair of waveguides Ci and Co with the transport of the film. In the oblique stretching zone Z2-2, the direction in which the film is conveyed is shifted in the middle so that the one waveguide Ci is relatively advanced and the other waveguide Co is relatively delayed so that the film is inclined Direction is carried out.

The relaxation zone Z3 is a relaxation zone in which after the end of the warp stretching process in the stretching zone Z2 the stress (residual stress) remaining on the film by oblique stretching is relaxed by the temperature setting described later It is John. In the relaxation zone Z3, the relaxation zone Z3 is also referred to as a heat-fixing zone in that the optical axis (slow axis) of the obliquely-stretched film is fixed. In the relaxation zone Z3, the waveguides Ci and Co at both ends may run parallel to each other. Alternatively, the film may be shrunk in the width direction and then run in parallel. In any case, in the relaxation zone Z3, the transport path of the film is not bent like the oblique stretching zone Z2-2, and the transport direction of the film is constant.

The stretched film may pass through a zone (cooling zone) where the temperature in the zone is set to be equal to or lower than the glass transition temperature Tg (占 폚) of the thermoplastic resin constituting the film after passing through the relaxation zone Z3.

The temperature of the preheating zone Z1 is from Tg to Tg + 60 占 폚, the temperature of the stretching zone Z2 is from Tg to Tg + 50 占 폚, the relaxation zone Z3 and the temperature of the cooling zone Is preferably set to Tg-40 to Tg + 30 占 폚.

The lengths of the preheating zone Z1, stretching zone Z2 and relaxation zone Z3 can be selected as appropriate and the length of the preheating zone Z1 is usually 50 to 200% , And the relaxation zone Z3 is usually 50 to 150%.

When the width of the film before stretching is Wo (mm) and the width of the film after stretching is W (mm), the stretching magnification R (W / Wo) in the stretching step is preferably 1.1 to 3.0 And preferably 1.3 to 2.0. When the stretching magnification falls within this range, thickness irregularity in the width direction of the film becomes small, which is preferable.

[Temperature control in oblique stretching zone and relaxation zone]

Next, the temperature control in the warp stretching zone Z2-2 and the relaxation zone Z3 will be described. Hereinafter, in the width direction of the film, it is assumed that the side on which one of the pair of waveguides Ci and Co runs ahead (the side on which the waveguide Ci runs) at the time of oblique stretching is referred to as a leading side , And the other side (the side on which the wave earth Co runs) is referred to as a delay side.

Fig. 3 schematically shows the temperature distribution from the delay side to the preceding side in the warp stretching zone Z2-2 and the relaxation zone Z3. In the present embodiment, in the oblique stretching zone Z2-2, a first temperature distribution is formed in which the temperature on the preceding side is lower by 1 占 폚 to 15 占 폚 than the temperature on the retarding side between the leading side and the retarding side . That is, when the temperature on the delay side of the oblique stretching zone Z2-2 is T1 (占 폚) and the temperature on the preceding side is T2 (占 폚)

1 ° C ≤ (T1-T2) ≤15 ° C ... (One)

to be. Particularly, in the warp stretching zone Z2-2, the warp and stretch zones Z2-2 and Z2-2, when a pair of waveguides (Ci and Co) holding the both ends of the film before the oblique stretching reaches the warp stretch end positions (P and Q) The first temperature distribution is formed in a direction connecting the pair of wave earths (Ci, Co) (hereinafter also referred to as PQ direction). At this time, the oblique stretching end positions (P, Q) are located immediately before the partition dividing the oblique stretch zone Z2-2 and the relaxation zone Z3, that is, on the upstream side in the film transport direction with respect to the partition do. The position for forming the first temperature distribution may be any place in the oblique stretching zone Z2-2 and is not limited to the position (the position connecting the oblique stretching end positions (P, Q)) .

Fig. 4 shows an example of the first temperature distribution in the warp stretched zone Z2-2. The first temperature distribution is a distribution in which the temperature monotonously decreases from the retarded side to the preceding side. For example, as shown by the straight line a1, the first temperature distribution may be a distribution in which the temperature decreases at a constant rate (a constant distribution of temperature gradient) from the delay side to the preceding side, and the curve a2 As shown by the curve a3, the distribution is a distribution in which the amount of decrease in temperature with respect to the amount of change in the position in the width direction becomes larger as the direction from the delay side toward the preceding side increases. Or a distribution in which the amount of temperature decrease relative to the amount of change in position is reduced.

On the other hand, as shown in Fig. 3, in the relaxation zone Z3, a second temperature distribution in which the temperature on the preceding side is higher than the temperature on the delay side by 5 占 폚 to 30 占 폚 is formed between the preceding side and the delay side . That is, when the temperature on the preceding side in the relaxation zone Z3 is T3 (占 폚) and the temperature on the delay side is T4 (占 폚)

5 ° C? (T3-T4)? 30 ° C ... (2)

to be. Particularly, in the relaxation zone Z3, the second temperature distribution is formed in the width direction passing through the middle point M3 of the relaxation zone Z3 and perpendicular to the film conveyance direction. Here, the midpoint M3 is a point at which the pair of waveguides Ci and Co reach the obliquely-drawn end positions P and Q in the oblique drawing zone Z2-2, The middle of the section connecting the first position M1 that is the middle of the section connecting the regions Ci and Co and the second position M2 that is the middle of the width direction of the exit of the mitigation zone Z3 Position (third position). The position for forming the second temperature distribution may be any position within the relaxation zone Z3 and is not limited to the above position.

Fig. 5 shows an example of the second temperature distribution in the relaxation zone Z3. The second temperature distribution is a distribution in which the temperature monotonically increases from the retarded side to the preceding side. For example, the second temperature distribution may be a distribution in which the temperature increases at a constant rate (a constant distribution of the temperature gradient) from the delay side to the preceding side as shown by the straight line b1, and the curve b2 As shown by the curve b3, the temperature increase amount with respect to the change amount of the position in the width direction becomes smaller as the temperature increases from the delay side to the preceding side The larger the distribution.

Further, the temperature of the oblique stretching zone Z2-2 is 5 占 폚 to 40 占 폚 higher than the temperature of the relaxation zone Z3. More specifically, the temperature of the first position M1 of the oblique stretching zone Z2-2 is 5 占 폚 to 40 占 폚 higher than the temperature of the middle point M3 (third position) of the relaxation zone Z3. That is, when the temperature of the first position M1 of the oblique stretching zone Z2-2 is T5 (占 폚) and the temperature of the middle point M3 of the relaxation step Z3 is T6 (占 폚)

5 ° C? (T5-T6)? 40 ° C ... (3)

to be. The temperature of the oblique stretching zone Z2-2 may be a temperature other than the first position M1 within the oblique stretching zone Z2-2. The temperature of the relaxation zone Z3 may also be a temperature other than the midpoint M3 in the relaxation zone Z3.

The temperature control satisfying the above-mentioned conditional expressions (1) to (3) is carried out by arranging the heating sections 11 and 12 respectively in the warp stretching zone Z2-2 and the relaxation zone Z3 . The heating units 11 and 12 have, for example, ejection openings for ejecting hot air, and are formed by long nozzles extending from the preceding side to the retarded side for heating the film by the hot air. The heating section 11 is formed in such a shape that the width of the jet port (opening width perpendicular to the longitudinal direction) widens from the leading side toward the retarded side. On the other hand, the heating section 12 is formed in such a shape that the width of the jet port (opening width perpendicular to the longitudinal direction) widens from the delay side toward the leading side. Thus, in the oblique stretching zone Z2-2, the first temperature distribution in which the temperature is higher on the delay side than on the preceding side can be realized, and in the relaxation zone Z3, 2 temperature distribution can be realized. The temperature of the hot air blown out from the heating unit 11 is set higher than the temperature of hot air blown out from the heating unit 12 so that the temperature of the oblique stretching zone Z2-2 is set higher than the temperature of the mitigation zone Z3 can do.

Further, the heating sections 11 and 12 may be constituted by nozzles having a uniform opening width of the jet port. In this case, the first temperature distribution and the second temperature distribution can be formed by changing the temperature of the hot air to be blown on the leading side and the delayed side. The temperature of the hot air blown out from the heating unit 11 is made higher than the temperature of hot air blown out from the heating unit 12 so that the temperature of the oblique stretching zone Z2-2 is set higher than the temperature of the mitigation zone Z3 can do.

Further, the heating units 11 and 12 may be constituted by an infrared heater instead of a nozzle for ejecting hot air. The first temperature distribution and the second temperature distribution can be formed by arranging a plurality of infrared heaters between the front side and the delay side and adjusting the output (wattage) of each infrared heater. By changing the output of the infrared heater in the heating section 11 and the heating section 12, the temperature of the oblique stretching zone Z2-2 can be made higher than the temperature of the relaxation zone Z3.

Fig. 7 schematically shows another example of the means for forming the second temperature distribution. In the furnace of the stretching section 5, in particular, in the oblique stretching region in which the conveying path is bent, the furnace tends to fill the furnace on the delay side of the bent portion. As a result, as shown in Fig. 7, the exhaust ability (the exhaust amount per unit time) of the exhaust part E1 on the preceding side is made higher than the exhaust ability of the exhaust part E2 on the delay side in the relaxation zone Z3 , And the heat accumulated in the furnace may be moved to the preceding side on the delay side, thereby forming the second temperature distribution. Specifically, a method of approaching the position of the exhaust port on the preceding side closer to the rail side than the position of the exhaust port on the delay side, or enlarging the area of the exhaust port on the preceding side than the area of the exhaust port on the delay side is considered. The air exhausted from the exhaust sections E1 and E2 may be returned to the furnace of the stretching section 5 to circulate the inside of the furnace, and may not be circulated. When the volume of the stretching zone Z2 in which the oblique stretching is performed is made larger on the retard side than on the preceding side, it is more preferable because the heat becomes less likely to fill up on the retard side.

By satisfying the conditional expressions (1) to (3), the film thickness difference in the film width direction generated in the warp stretching process can be reduced by relaxation of the residual stress in the relaxation process, A film can be obtained. Thus, the productivity of the warp stretched film can be improved while reducing the occurrence of wrinkles. Hereinafter, this point will be described in more detail.

In the bending type warp stretching method in which the film transport direction is bent in the middle, the pair of wave fringes Ci and Co run asymmetrically in the film width direction, and the tension applied to the film becomes uneven in the width direction , The film thickness on the leading side of the film after the warp stretching becomes thick, and the film thickness on the retarded side becomes thin as described above. The shape of the surface of the film at this time becomes, for example, as indicated by the broken line in Fig.

In the warp stretching zone Z2-2 where the condition (1) is satisfied, that is, by raising the temperature on the delay side from the preceding side, stress (tension) and residual stress (residual stress) Can be reduced on the delay side and kept at the minimum on the leading side. In the relaxation zone Z3 which satisfies the conditional expression (2), by increasing the temperature on the leading side from the retarded side, the relaxation is suppressed while relaxing the residual stress on the retarded side, The relaxation of the residual stress can be promoted. As described above, it is possible to reduce the film thickness of the film on the preceding side and to reduce the fluctuation of the film thickness in the width direction of the film. The shape of the surface of the film after the relaxation process becomes as shown by the solid line in Fig.

Further, by causing a difference in temperature of not less than 5 DEG C and not more than 40 DEG C in the oblique stretching zones Z2-2 and Z3 satisfying the condition (3), the residual stress generated in the film by the warp stretching is relaxed. (Z3), and it is easier to obtain the effect of reducing the fluctuation of the film thickness in the width direction of the film.

Therefore, in producing an obliquely-elongated film having almost uniform film thickness, it is not necessary to prepare and prepare a special film whose film thickness is varied in the width direction in advance. As a result, the productivity of the warp stretched film can be improved. Further, since the residual stress applied to the film by the warp stretching in the oblique stretching zone Z2-2 is appropriately relaxed in the relaxation zone Z3, the ribs of the ribs It is possible to reduce the occurrence of chafing. That is, by satisfying the conditional expressions (1) to (3), the productivity of the warp stretched film can be improved while reducing the occurrence of wrinkles.

Further, in the oblique stretching zone Z2-2, when T1-T2 is 1 占 폚 or more, the tension and residual stress at the retarded side can reliably be reduced, and the residual stress can be reliably maintained at the leading side. Thereby, when the second temperature distribution is formed in the relaxation zone Z3, the stress is excessively relaxed in the leading side, the film thickness becomes smaller on the leading side than the retarded side, and the film thickness is prevented from becoming uneven in the width direction . On the other hand, when T1-T2 is 15 占 폚 or less, excessive reduction of the residual stress on the delay side can be avoided. Thereby, when the second temperature distribution is formed in the relaxation zone Z3, it is possible to avoid situations in which the film thickness on the leading side is not close to the film thickness on the retarded side even by the stress relaxation on the leading side, , It is possible to avoid that the film thickness becomes uneven in the width direction.

In addition, in the relaxation zone Z3, since the stress relaxation at the leading side of the relaxation zone Z3 is too small, the decrease in the thickness of the leading side can be prevented from being lowered because T3-T4 is 5 DEG C or more. On the other hand, when T3-T4 is 30 占 폚 or less, stress relaxation on the leading side of the relaxation zone Z3 is excessively large, thereby avoiding an increase in the amount of decrease in the thickness of the leading side. In any event, it is possible to avoid the film thickness from becoming non-uniform in the width direction.

In the oblique drawing zone Z2-2, the direction connecting the oblique drawing end positions P and Q (the direction connecting the waveguides Ci and Co reaching the oblique drawing end positions P and Q) , The first temperature distribution is formed. In the oblique stretching zone Z2-2, the line connecting the oblique stretching end positions (P, Q) is the position where the tension (tension) in oblique stretching is the largest. Therefore, by forming the first temperature distribution at such a position, the method of the present embodiment in which the second temperature distribution is formed in the relaxation zone Z3 to reduce the fluctuation of the film thickness in the width direction of the film becomes very effective .

In the relaxation zone Z3, the second temperature distribution is formed in the width direction passing through the midpoint M3 described above and perpendicular to the transport direction. By forming the second temperature distribution at the average position of the entire relaxation zone Z3, it is possible to reliably obtain the effect of reducing the film thickness of the film on the preceding side and reducing the fluctuation of the film thickness in the width direction of the film.

The temperature of the first position M1 of the oblique stretching zone Z2-2 is 5 占 폚 to 40 占 폚 higher than the temperature of the middle point M3 of the relaxation zone Z3. By setting the temperature difference for the first position M1 and the middle point M3 as described above, the setting of the conditional expression (3) becomes more effective.

Since the first temperature distribution is a distribution in which the temperature monotonically decreases from the delay side to the preceding side, it is possible to surely realize a temperature distribution (first temperature distribution) in which the temperature on the preceding side becomes lower than the temperature on the delay side have.

Similarly, since the second temperature distribution is a distribution in which the temperature monotonically increases from the delay side to the preceding side, it is possible to reliably realize a temperature distribution (second temperature distribution) in which the temperature on the preceding side becomes higher than the temperature on the delay side .

Incidentally, in the warp stretching zone Z2-2, the film may be stretched in an oblique direction so that the slow axis is at an angle of 30 DEG to 60 DEG with respect to the width direction of the film. Particularly, in the case of producing a long polarizing plate by joining a long oblong stretched film and a long polarizing film (long polarizing film) by a roll-to-roll method, from the viewpoint of dramatically improving the productivity of the circularly polarizing plate , And the film is stretched in the oblique direction so that the slow axis is at an angle of about 45 with respect to the width direction of the film, thereby producing a long obliquely stretched film. Also, the term &quot; approximately 45 DEG &quot; includes a range of 45 DEG +/- 3 DEG.

(Other)

In the oblique stretching process, the transporting speed of the film may be 1 to 150 m / min. From the viewpoint of improving the productivity of the film, the transporting speed of the film is preferably from 10 to 120 m / min, more preferably from 20 to 100 m / min.

&Lt; Quality of long oblique stretched film >

In the long oblong stretched film obtained by the production method of the present embodiment, the orientation angle? Is inclined to a range of, for example, more than 0 DEG and less than 90 DEG with respect to the winding direction, Plane retardation Ro is 2 nm or less and the variation of the orientation angle [theta] is less than 0.6 [deg.]. The in-plane retardation value Ro (550) of the long oblong stretched film measured at a wavelength of 550 nm is preferably in a range of 80 nm or more and 160 nm or less, and more preferably 90 nm or more and 150 nm or less.

That is, in the long oblong stretched film obtained by the production method of the present embodiment, the fluctuation of the in-plane retardation Ro is preferably 2 nm or less and 1 nm or less at 1300 mm in the width direction. When the fluctuation of the in-plane retardation Ro is in the above-mentioned range, a long oblong stretched film is bonded to the polarizer to form a circularly polarizing plate. When this is applied to an organic EL image display apparatus, Can be suppressed. In addition, when a long oblong stretched film is used as a retardation film for a liquid crystal display device, for example, the display quality can be made good.

In the long oblong stretched film obtained by the manufacturing method of the present embodiment, the variation of the orientation angle? Is preferably less than 0.6 deg., Less than 0.4 deg., And less than 0.2 deg. Is most preferable. When a long oblong stretched film having a variation of an orientation angle? Of more than 0.6 is bonded to a polarizer to form a circularly polarizing plate and this film is provided in an image display apparatus such as an organic EL display, light leakage occurs, In some cases.

The in-plane retardation Ro of the long oblong drawn film obtained by the production method of this embodiment is selected in accordance with the design of the display device to be used. Ro is a value obtained by multiplying the difference between the refractive index nx in the in-plane slow axis direction and the refractive index ny in the plane perpendicular to the slow axis in the plane (Ro = (nx-ny) xd )to be.

The average thickness of the long oblong drawn film obtained by the production method of the present embodiment is preferably 1 to 400 占 퐉, preferably 10 to 200 占 퐉, more preferably 10 to 60 占 퐉, particularly preferably Lt; / RTI &gt;

The long warp stretched film obtained by the production method of this embodiment may have a functional layer on its surface. The functional layer may be an antireflection layer, a low refractive index layer, a hard coating layer, a light scattering layer, a light diffusion layer, an antistatic layer, a conductive layer, an electrode layer, a birefringent layer, a surface energy adjustment layer, a UV absorption layer, A heat resistant layer, a magnetic layer, an oxidation preventing layer, an overcoat layer, and the like.

<Circular Polarizer>

In the circular polarizer of the present embodiment, a polarizing plate protective film, a polarizer and a lambda / 4 film are laminated in this order, and the angle formed by the slow axis of the lambda / 4 film and the absorption axis (or transmission axis) . When the circular polarizer of the present embodiment is used in an organic EL display device, the polarizer protective film, the polarizer, and the? / 4 film are the same as the protective film 313, the polarizer 311, the? / 4 film 316, Respectively. In the present embodiment, it is preferable that a long-type polarizing plate protective film, a long-type polarizing film, and a long lambda / 4 film (long obliquely stretched film) are laminated in this order.

When the circular polarizer of the present embodiment is used in a liquid crystal display, the polarizer protective film, the polarizer, and the? / 4 film are the same as the protective film 506, the polarizer 501, the? / 4 film 503 Respectively. A protective film 506 and a polarizer 501 are disposed outside (on the viewing side) of the display cell 401 and a lambda / 4 film 503 is disposed on the viewer side (on the viewing side) of the polarizer 501 Therefore, the linearly polarized light emitted from the display cell 401 and transmitted through the polarizer 501 is converted into circularly polarized light or elliptically polarized light by the? / 4 film 503. Therefore, in the case where the observer observes the display image of the display device 400 by attaching the polarizing sunglasses, even when observing at any angle (the transmission axis of the polarizer 501 (perpendicular to the absorption axis) It is possible to observe the display image by guiding the component of light parallel to the transmission axis of the polarizing sunglass to the eyes of the observer so that it is possible to suppress the display image from being hardly seen in accordance with the viewing angle.

The circular polarizer of the present embodiment can be produced by using a polarizer obtained by stretching polyvinyl alcohol doped with iodine or a dichroic dye and bonding it with a constitution of? / 4 film / polarizer. The film thickness of the polarizer is 5 to 40 占 퐉, preferably 5 to 30 占 퐉, and particularly preferably 5 to 20 占 퐉.

The polarizing plate can be manufactured by a general method. The alkali saponified? / 4 film is preferably bonded to one side of a polarizer prepared by immersing and stretching a polyvinyl alcohol film in an iodine solution using a fully saponified polyvinyl alcohol aqueous solution.

The polarizing plate may be constituted by bonding a peeling film to the opposite surface of the polarizing plate protective film of the polarizing plate. The protective film and the release film are used for the purpose of protecting the polarizing plate at the time of polarizing plate shipment, product inspection and the like.

<Organic EL Display Device>

9 is a cross-sectional view showing a schematic structure of an organic EL display device 100 as an OLED according to the present embodiment. The configuration of the organic EL display device 100 is not limited to this.

The organic EL display device 100 is configured by forming a circularly polarizing plate 301 on an organic EL element 101 with an adhesive layer 201 interposed therebetween. The organic EL element 101 includes a metal electrode 112, a light emitting layer 113, a transparent electrode (such as ITO) 114, and a sealing layer 115 in this order on a substrate 111 using glass or polyimide Respectively. The metal electrode 112 may be composed of a reflective electrode and a transparent electrode.

The circularly polarizing plate 301 includes a quarter wave film 316, an adhesive layer 315, a polarizer 311, an adhesive layer 312, a protective film 313, and a cured layer 314 in this order from the organic EL element 101 side The polarizer 311 is sandwiched between the? / 4 film 316 and the protective film 313. The polarizer 311 is bonded to the circular polarizer 311 such that the angle formed by the transmission axis of the polarizer 311 and the slow axis of the? / 4 film 316 including the long obliquely stretched film of the present embodiment is about 45 ° (or 135 °) (301).

The protective film 313 preferably has a cured layer 314 laminated thereon. The cured layer 314 not only prevents surface scratches of the organic EL display device 100 but also has an effect of preventing warping by the circularly polarizing plate 301. [ Also, an antireflection layer may be formed on the cured layer 314. The thickness of the organic EL element 101 itself is about 1 mu m.

When a voltage is applied to the metal electrode 112 and the transparent electrode 114 in the above configuration, electrons are injected into the light emitting layer 113 from the metal electrode 112 and the transparent electrode 114, which are cathodes, , Holes are injected from the electrode serving as the anode, and both are recombined in the light emitting layer 113, whereby visible light corresponding to the light emitting property of the light emitting layer 113 is emitted. Light generated in the light emitting layer 113 is directly or reflected by the metal electrode 112 and then is taken out to the outside through the transparent electrode 114 and the circularly polarizing plate 301.

Generally, in an organic EL display device, a light emitting element (organic EL element) is formed by sequentially laminating a metal electrode, a light emitting layer, and a transparent electrode on a transparent substrate. Here, the light emitting layer is a laminate of various organic thin films, for example, a laminate of a hole injecting layer containing a triphenylamine derivative or the like and a light emitting layer containing a fluorescent organic solid such as anthracene, or a laminate of such a light emitting layer and a perylene derivative And a multilayer body of the hole injection layer, the light emitting layer, and the electron injection layer are known.

In the organic EL display device, holes and electrons are injected into the light emitting layer by applying a voltage to the transparent electrode and the metal electrode, and the energy generated by the recombination of the holes and the electrons excites the fluorescent substance, And emits light when it returns to the state. The mechanism of recombination in the middle is similar to that of a general diode, and as can be expected from this point, the current and the light emission intensity exhibit strong nonlinearity accompanied by rectification with respect to the applied voltage.

In the organic EL display device, at least one of the electrodes must be transparent in order to extract light from the light emitting layer, and a transparent electrode formed of a transparent conductor such as indium tin oxide (ITO) is usually used as the anode. On the other hand, it is important to use a substance having a low work function for the cathode in order to facilitate electron injection and increase the luminous efficiency, and metal electrodes such as Mg-Ag and Al-Li are generally used.

In the organic EL display device having such a structure, the light emitting layer is formed of an extremely thin film with a thickness of about 10 nm. As a result, the light emitting layer almost completely transmits the light, like the transparent electrode. As a result, light emitted from the surface of the transparent substrate at the time of non-emission and transmitted through the transparent electrode and the light-emitting layer and reflected by the metal electrode is again directed to the surface side of the transparent substrate. The display surface looks like a mirror.

The circularly polarizing plate of the present embodiment is suitable for an organic EL display device in which such external light reflection is particularly problematic.

That is, half of the external light incident from the outside of the organic EL element 101 by the room illumination or the like is absorbed by the polarizer 311 of the circularly polarizing plate 301 at the time of non-emission of the organic EL element 101, Half of the light is transmitted as linearly polarized light, and is incident on the? / 4 film 316. The light incident on the? / 4 film 316 is incident on the? / 4 film 316 because the transmission axis of the polarizer 311 and the slow axis of the? / 4 film 316 intersect at 45 degrees (or 135 degrees) And is converted into circularly polarized light by passing through the film 316.

The circularly polarized light emitted from the lambda / 4 film 316 is mirror-reflected by the metal electrode 112 of the organic EL element 101, and is inverted in phase by 180 degrees and reflected as circularly polarized light in the reverse direction. The reflected light is converted into linearly polarized light perpendicular to the transmission axis of the polarizer 311 (parallel to the absorption axis) when it is incident on the? / 4 film 316, so that all of the reflected light is absorbed by the polarizer 311, . That is, by the circularly polarizing plate 301, reflection of external light in the organic EL element 101 can be reduced.

<Liquid Crystal Display Device>

10 is a cross-sectional view showing a schematic configuration of a display device 400 as a liquid crystal display device of the present embodiment. The display device 400 is constituted by disposing a polarizing plate 402 on one side of the display cell 401.

In the case of a liquid crystal display device, the display cell 401 can be a liquid crystal cell in which a liquid crystal layer is sandwiched between a pair of substrates. Further, on the opposite side of the liquid crystal cell to the polarizing plate 402, there are provided a polarizing plate 402, another polarizing plate arranged in a cross-Nicol state, and a backlight for illuminating the liquid crystal cell, but these are omitted in Fig.

The display device 400 may have a front window 403 on the side opposite to the display cell 401 with respect to the polarizing plate 402. [ The front window 403 is an outer cover of the display device 400, and is constituted by, for example, a cover glass. Between the front window 403 and the polarizing plate 402, a filler 404 containing, for example, an ultraviolet curable resin is filled. An air layer is formed between the front window 403 and the polarizing plate 402. When the front window 403 and the polarizing plate 402 are in contact with the air layer, The visibility of the image may be deteriorated. However, since the air layer is not formed between the front window 403 and the polarizing plate 402 by the filler 404, deterioration of the visibility of the display image due to reflection of light at the interface can be avoided.

The polarizing plate 402 has a polarizer 501 which transmits a predetermined linearly polarized light. The? / 4 film 503 and the cured layer 504 including the ultraviolet curable resin are bonded to one side (opposite to the display cell 401) of the polarizer 501 via the adhesive layer 502 in this order As shown in FIG. A protective film 506 is bonded to the other surface side (the display cell 401 side) of the polarizer 501 with an adhesive layer 505 interposed therebetween.

The polarizer 501 is obtained, for example, by staining a polyvinyl alcohol film with a dichromatic dye and stretching it at a high magnification. After the polarizer 501 is subjected to an alkali treatment (also referred to as a saponification treatment), a lambda / 4 film 503 is bonded to one side via an adhesive layer 502 and a protective film 506 is bonded to the other side 505, respectively.

The adhesive layers 502 and 505 are layers including, for example, a polyvinyl alcohol adhesive (PVA adhesive, waterbath), but may be a layer containing an ultraviolet curable adhesive (UV adhesive). These adhesives are liquids in the state of being applied to the adhesive surface, and are cured by drying or ultraviolet irradiation after application, thereby adhering them. That is, the adhesive layers 502 and 505 adhere the polarizer 501 and the? / 4 film 503, and the polarizer 501 and the protective film 506, respectively, due to the state change from the liquid phase. As described above, the adhesive layers 502 and 505 are different from the adhesive layer (sheet-like adhesive layer having a pressure-sensitive adhesive on the substrate) for adhering them without causing such a state change in that they adhere to each other due to a change in state from the liquid phase It is different.

The? / 4 film 503 is a layer which gives an in-plane retardation of about 1/4 of the wavelength of transmitted light. In the present embodiment, for example, the? / 4 film 503 contains a cellulose resin (cellulose polymer). The? / 4 film 503 may contain a polycarbonate resin (polycarbonate-based polymer) instead of the cellulose-based polymer, or may include a cycloolefin-based resin (cycloolefin-based polymer). However, from the viewpoint of chemical resistance, it is preferable that the? / 4 film 503 contains a cellulose polymer or a polycarbonate polymer.

The? / 4 film 503 is a? / 4 film of a thin film having a thickness of 10 mu m to 70 mu m. The angle (angle of intersection) between the slow axis of the λ / 4 film 503 and the absorption axis of the polarizer 501 is 30 ° to 60 ° so that the linearly polarized light from the polarizer 501 becomes λ / 4 film 503 into circularly polarized light or elliptically polarized light.

The cured layer 504 (also referred to as a hard coat layer) is composed of an active energy ray curable resin (for example, an ultraviolet curable resin).

The protective film 506 is composed of an optical film including, for example, a cellulose-based resin (a cellulose-based polymer), an acrylic resin, a cyclic polyolefin (COP), and a polycarbonate (PC). Although the protective film 506 is provided as a film for simply protecting the back surface of the polarizer 501, it may be provided as an optical film serving also as a retardation film having a desired optical compensation function.

In the case of a liquid crystal display device, a separate polarizing plate disposed on the side opposite to the polarizing plate 402 with respect to the display cell 401 (liquid crystal cell) is constituted by sandwiching the surface of the polarizing film between two optical films. As the polarizer and the optical film, those similar to the polarizer 501 and the protective film 506 of the polarizing plate 402 can be used.

Here, the polarizer 501 and the? / 4 film 503 may each have a long shape. In this case, it is preferable that the slow axis of the? / 4 film 503 is inclined by 30 to 60 degrees with respect to the longitudinal direction of the? / 4 film 503. In this case, the long λ / 4 film 503 is formed by oblique drawing to form a roll-shaped film, which is then joined to the roll-type polarizer 501 by so-called roll- 402 can be manufactured. Therefore, as compared with the case where the polarizing plate 402 is manufactured in a batch mode in which the film pieces are bonded one by one, the productivity is remarkably improved and the yield can be greatly improved.

Further, an easy adhesion layer for improving the adhesiveness of the? / 4 film 503 may be formed on the adhesive layer 502 side of the? / 4 film 503. The adhesion facilitating layer is formed by performing an adhesion facilitating treatment on the adhesive layer 502 side of the? / 4 film 503. As the adhesion facilitating treatment, there are corona (discharge) treatment, plasma treatment, frame treatment, ittro treatment, glow treatment, ozone treatment, primer coating treatment and the like. Among these adhesion facilitating treatments, from the viewpoint of productivity, the corona treatment and the plasma treatment are preferable as the adhesion facilitating treatment.

<Examples>

Hereinafter, examples that are specific examples of the production of the warp stretched film in the present embodiment will be described with reference to comparative examples. The present invention is not limited to the following examples. In the following, the notation &quot; part &quot; or &quot;% &quot; is used, and unless otherwise stated, they represent "part by mass" or "% by mass".

[Fabrication of Fabric Film]

A long film 1 as a raw film was produced by the following method. The long film 1 is a cellulose ester based resin film.

&Quot; Fine particle dispersion liquid &

Fine particles (Aerosil R972V manufactured by Nippon Aerosil Co., Ltd.) 11 parts by mass

ethanol 89 parts by mass

The resulting mixture was stirred with a dissolver for 50 minutes and then dispersed with mannitol to prepare a fine particle dispersion 1.

&Lt; Particulate additive liquid &

On the basis of the following composition, the fine particle dispersion was added slowly while stirring well in a dissolution tank containing methylene chloride. And dispersed by an attritor so that the particle diameter of the secondary particles became a predetermined value. This was filtered with Fine Mat NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle addition liquid 1.

Methylene chloride 99 parts by mass

Fine Particle Dispersion 1 5 parts by mass

«Juodope»

To prepare a main dope liquid having the following composition. First, methylene chloride and ethanol were added to the pressure-melting tank. Cellulose acetate was added to the pressurized dissolution tank containing the solvent while stirring. The solution was completely dissolved while heating and stirring, and the solution was filtered using Azumi filter paper No. 244 made by Azumi Co., Ltd. to prepare a main dope solution. As the sugar ester compound and the ester compound, the compound synthesized by the following synthesis examples was used.

<< Composition of the main doping solution >>

Methylene chloride 340 parts by mass

ethanol 64 parts by mass

Cellulose acetate propionate (acetyl group substitution degree: 1.50, propionyl group substitution degree: 0.90, total substitution degree: 2.40) 100 parts by mass

Ester ester compound 5.0 parts by mass

Ester compound 5.0 parts by mass

Ultraviolet absorber 1.5 parts by mass

Particle addition liquid 1 1 part by mass

&Lt; Synthesis of sugar ester compound &

A sugar ester compound was synthesized by the following process.

34.2 g (0.1 mol) of sucrose, 180.8 g (0.6 mol) of anhydrous benzoic acid, and 379.7 g (4.8 mol) of pyridine were fed to four-necked colbins equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen gas- The temperature was elevated while nitrogen gas was bubbled through the nitrogen gas introduction tube, and the esterification reaction was carried out at 70 DEG C for 5 hours.

Subsequently, the inside of the colb is reduced to 4 × 10 ² Pa or less, excess pyridine is distilled off at 60 ° C., the pressure in corbene is reduced to 1.3 × 10 Pa or less and the temperature is raised to 120 ° C. to obtain an anhydrous benzoic acid Most were distilled off.

Finally, water (100 g) was added to the separated toluene layer, and the toluene layer was separated from the toluene layer after washing at room temperature for 30 minutes. Toluene was distilled off at 60 캜 under reduced pressure (4 × 10 ² Pa or less) A mixture (a sugar ester compound) of the compounds A-1, A-2, A-3, A-4 and A-5 was obtained.

The obtained mixture was analyzed by HPLC and LC-MASS to find that 1.3 mass% of A-1, 13.4 mass% of A-2, 13.1 mass% of A-3, 31.7 mass% of A- Mass%. The average degree of substitution was 5.5.

<< Measurement conditions of HPLC-MS >>

1) LC section

(JASCO CO-965), detector (JASCO UV-970-240nm), pump (JASCO PU-980), degasser (JASCO DG-980-50) manufactured by Nippon Bunko Co.,

Column: Inertsil ODS-3, particle diameter 5 占 퐉, 4.6 占 250 mm (manufactured by GL Science Co., Ltd.)

Column temperature: 40 DEG C

Flow rate: 1 ml / min

Mobile phase: THF (1% acetic acid): H ₂ O (50:50)

Injection volume: 3μl

2) MS Department

Apparatus: LCQ DECA (manufactured by Thermo Quest Co., Ltd.)

Ionization method: Electrospray ionization (ESI) method

Spray voltage: 5kV

Capillary temperature: 180 ° C

Vaporizer temperature: 450 DEG C

&Lt; Synthesis of ester compound &

An ester compound was synthesized by the following steps.

251 g of 1,2-propylene glycol, 278 g of phthalic anhydride, 91 g of adipic acid, 610 g of benzoic acid and 0.191 g of tetraisopropyl titanate as an esterification catalyst were put into a 2 L four-necked flask equipped with a thermometer, , And the temperature is gradually raised while stirring in a nitrogen stream until the temperature becomes 230 캜. After completion of the reaction, unreacted 1,2-propylene glycol was distilled off under reduced pressure at 200 占 폚 to obtain an ester compound. The ester compound has an ester of benzoic acid at the end of the polyester chain formed by condensation of 1,2-propylene glycol, phthalic anhydride and adipic acid. The acid value of the ester compound was 0.10, and the number average molecular weight was 450.

Subsequently, using an endless belt flexing device, it was uniformly flexible on the stainless steel belt support.

In the endless belt flexing apparatus, the main dope liquid was uniformly softened on the stainless steel belt support. On the stainless steel belt support, the solvent was evaporated until the amount of the residual solvent in the long film (cast) was 75%, peeled off on the stainless steel belt support, and dried while conveying in a plurality of rolls, Film 1 was obtained.

[Production of warp stretched film]

The long film 1 comprising the above-prepared cellulose resin was supplied to the stretching section 5 of the production apparatus 1 shown in Fig. 1 to perform oblique stretching and the temperature of each zone of the stretching section 5 was controlled , And a long oblique stretched film was obtained (see Examples 1 to 13 and Comparative Examples 1 to 5 in Table 1). At this time, in the stretching section 5, oblique stretching was carried out so that the orientation angle of the film (the angle between the slow axis and the width direction) was approximately 45 占 and the film conveying speed was 15 m / min. The stretching magnification of the film before and after stretching was 1.2 times in Examples 1 to 12 and Comparative Examples 1 to 4 and 1.4 times in Example 13 and Comparative Example 5 and the final film width after trimming treatment Was set to 2000 mm. The temperature condition in the stretching section 5 was changed as shown in Table 1 to prepare a warp stretched film. The design film thickness of the warp stretched film at this time was set to a value shown in Table 1.

6 (nozzles) shown in Fig. 6 are disposed in the elongating zone Z2 (particularly, the warp stretching zone Z2-2) and the relaxation zone Z3 of the stretching section 5, Respectively. In the oblique stretching zone Z2-2, a first temperature distribution shown by a straight line a1 in Fig. 4 was formed in a direction passing through the oblique stretching end position (P, Q) in Fig. In the relaxation zone Z3, the second temperature distribution shown by the straight line b1 in Fig. 5 was formed in the width direction passing through the intermediate point M3 and perpendicular to the conveying direction.

The temperature T1 (占 폚) on the delay side and the temperature T2 (占 폚) on the preceding side in the first temperature distribution are 2 points inward of the rail by the rail width (rail interval) 占 5% P, Q), and the measured temperatures of the delay side and the preceding side are respectively referred to as a temperature T1 and a temperature T2. The temperature T3 (占 폚) on the leading side and the temperature T4 (占 폚) on the delay side in the second temperature distribution are two points inside the rail by the rail width 占 5% And the measured temperatures on the leading side and the delayed side were respectively referred to as a temperature T3 and a temperature T4. The temperature of the first position M1 of the oblique stretching zone Z2-2 is T5 (占 폚), the temperature of the middle point M3 of the relaxation zone Z3 is T6 (占 폚) The respective temperatures T5 and T6 were measured. The temperatures T1 to T6 were obtained by measuring the temperature of the film side from the position of 150 mm below the film conveyed in each zone by using a heat resistant type non-contact temperature sensor (IRtec Rayomatic 14, manufactured by Eurotron Co., Ltd.) .

Tl = 200.5 占 폚, T2 = 199.5 占 폚, T3 = 197.5 占 폚, T4 = 192.5 占 폚, T5 = 200 占 폚, and T6 = 200.5 占 폚 in the production of the warp stretched film of Example 1 as an example of the temperatures T1 to T6. 195 ° C. In the other examples and comparative examples, the temperature of each zone of the stretching section 5 was controlled so as to be the temperature difference shown in Table 1. The temperatures in the preheating zone Z1 and the transverse stretch zone Z2-1 were the same and substantially the same as the temperature T1 on the retard side of the oblique stretch zone Z2-2.

[evaluation]

(Evaluation of Film Thickness Deviation)

For each of the warp stretched films produced under the temperature conditions in Table 1, the film thickness was measured at intervals of 100 mm in the width direction using a Digimatic thickness gauge (manufactured by Mitsutoyo). This film thickness measurement is performed five times every 50 m in the film transport direction (longitudinal direction), and the difference between the maximum value and the minimum value of the total data (film thickness value) is determined as the film thickness deviation (占 퐉) The film thickness deviation was evaluated.

<< Evaluation Criteria >>

?: The film thickness deviation is larger than 0 占 퐉 and not larger than 0.5 占 퐉.

?: The film thickness deviation is larger than 0.5 占 퐉 and 1.0 占 퐉 or less.

X: The film thickness deviation is larger than 1.0 占 퐉 and 1.5 占 퐉 or less.

XX: Film thickness deviation is larger than 1.5 占 퐉.

(Evaluation of wrinkles)

Each of the obliquely drawn films produced under the temperature conditions in Table 1 was visually observed and the presence or absence of rib-like wrinkles (rub) was evaluated based on the following evaluation criteria.

<< Evaluation Criteria >>

O: Wrinkles were hardly observed.

?: Small wrinkles were observed, but there was no problem in actual use.

X: Large wrinkles were observed as problems in actual use.

Table 1 shows the evaluation results for each oblique stretched film.

In the warp stretched films of Examples 1 to 13 in Table 1, evaluation of the film thickness deviation was? Or?, And good results were obtained. (T3-T4)? 30 deg. C, 5 deg. C (T5 - T6)? 40 deg. C Is satisfied. That is, even if the film thickness is thin on the delay side and the film thickness on the leading side is increased by oblique stretching in the warp stretching zone Z2-2 by satisfying the above-mentioned temperature condition, The relaxation of the residual stress can be promoted and the film thickness can be reduced at the leading side of the film thickness direction, thereby making it possible to reduce the film thickness difference in the film width direction. In the warp stretched films of Examples 1 to 13, the evaluation of wrinkles was also good or good. However, this is because the residual stress in the relaxation zone Z3 was appropriately relaxed in the width direction. As a result, Is suppressed.

On the other hand, in the warp stretched films of Comparative Examples 1 to 5, the evaluation of the film thickness deviation was x or xx. This is because, in the production of the obliquely-drawn films of Comparative Examples 1 to 5, it is preferable that 1 占 폚 (T1-T2)? 15 占 폚, 5 占 폚? (T3-T4)? 30 占 폚, 5 占 폚 (T5-T6) The residual stress in the relaxation zone Z3 is not relaxed or the residual stress is excessively relaxed so that the fluctuation of the film thickness in the width direction becomes small so that the fluctuation of the film thickness It is thought that it is because it occurred. Particularly, in the warp stretched film of Comparative Example 1, it is considered that wrinkles due to the residual stress occurred as a result of the fact that the residual stress was not adequately relaxed.

It is also understood from the results of Examples 11 and 12 that even if the film thickness is thin, the occurrence of film thickness deviation and wrinkle can be reduced by appropriate temperature control in the warp stretching zone Z2-2 and relaxation zone Z3 .

From the results of Example 13, it is also possible to reduce the occurrence of film thickness deviation and wrinkles by appropriate temperature control in the warp stretching zone Z2-2 and the relaxation zone Z3 even if the stretch magnification changes . Further, in Comparative Example 5 in which the draw ratio was 1.4 times, it was considered that the film thickness variation occurred because 5 占 폚? (T5-T6)? 40 占 폚 was not satisfied similarly to Comparative Example 4 in which the draw ratio was 1.2 times.

As described above, in the production of the warp stretched films of Examples 1 to 13, even if oblique stretching is performed using a raw film having a uniform film thickness in the width direction, a warp stretched film having almost uniform film thickness in the width direction It is not necessary to prepare and prepare a special film whose film thickness is changed in the width direction as a raw material film. As a result, the productivity of the warp stretched film can be improved. Furthermore, since the generation of wrinkles attributed to the residual stress can be reduced, the productivity of the warp stretched film can be improved while reducing the occurrence of wrinkles.

Although the first temperature distribution formed in the oblique stretching zone Z2-2 is the distribution of the straight line a1 shown in Fig. 4, the distribution shown by the curves a2 and a3 is T1 -T2 was set appropriately, it was found that the same results as in Examples 1 to 13 were obtained. Therefore, it can be said that the first temperature distribution formed in the oblique stretching zone Z2-2 is a distribution surface in which the temperature monotonically decreases from the delay side to the preceding side.

In the above description, the second temperature distribution formed in the relaxation zone Z3 is the distribution of the straight line b1 shown in Fig. 5, but also the distribution shown by the curves b2 and b3 is T3-T4 It was found that the same results as in Examples 1 to 13 were obtained. Therefore, it can be said that the second temperature distribution formed in the relaxation zone Z3 is a distribution surface in which the temperature monotonously increases from the delay side to the preceding side.

In the above description, the description has been given of the example in which the film is subjected to the oblique stretching so that the orientation angle becomes approximately 45 占 However, even when the oblique stretching is performed so that the orientation angle of the film becomes 30 degrees or 60 degrees, By the same temperature control, it was found that the same results as in Examples 1 to 13 were obtained.

In the above description, the case where a warp stretched film is produced using a cellulose ester resin has been described. However, it is also possible to use a resin other than a cellulose ester resin such as COP or PC and perform the same temperature control as in Examples 1 to 13 It was found that the same results as in Examples 1 to 13 were obtained.

The above-described method of producing the warp stretched film of this embodiment can be expressed as follows.

1. The film is transported by gripping both ends of the film in the width direction with a pair of gripping portions and the transport direction of the film is shifted in the middle in the oblique stretching zone so that one wave earth is relatively advanced, Stretching the film in an oblique direction with respect to the width direction by relatively delaying the stretching direction of the film in the transverse direction,

Further comprising an alleviating step of alleviating the residual stress of the film by oblique stretching in a relaxation zone in which the film is conveyed in a constant direction after the oblique stretching step,

In the transverse direction of the film, when the side on which one of the pair of waveguide runs first in the oblique stretching is referred to as the leading side and the side in which the other is running in the retarded direction is referred to as the retarded side,

In the oblique stretching zone, a first temperature distribution is formed between the leading side and the retarding side in which the temperature on the preceding side is lower by 1 占 폚 to 15 占 폚 than the temperature on the retarding side,

Wherein the relaxation zone forms a second temperature distribution between the preceding side and the retarded side in which the temperature of the preceding side is higher by 5 占 폚 to 30 占 폚 than the temperature of the retarded side,

Wherein the temperature of the oblique stretching zone is 5 占 폚 to 40 占 폚 higher than the temperature of the relaxation zone.

2. The oblique stretching zone forms the first temperature distribution in a direction connecting the pair of waveguides when the pair of waveguides reaches the oblique stretching end position, respectively (2) The method of producing an obliquely-elongated film according to (1) above.

3. In the relaxation zone, the second temperature distribution is formed in the width direction passing through the intermediate point of the relaxation zone and perpendicular to the conveyance direction,

Wherein the midpoint is defined by a first position in the middle of a section connecting the pair of waveguides when the pair of waveguides reaches the oblique stretching end position in the oblique stretch zone, And the intermediate position of the section connecting the second position in the middle of the width direction of the outlet.

4. The temperature of the oblique stretching zone is a temperature at a first position which is the middle of a section connecting the pair of waveguides when the pair of waveguides reach the oblique stretching end position,

Wherein the temperature of the mitigation zone is a temperature of a third position that is the middle of a section connecting the first position and a second position intermediate the width direction of the exit of the mitigation zone,

The method of producing an obliquely-drawn film according to any one of 1 to 3 above, wherein the first temperature is higher by 5 占 폚 to 40 占 폚 than the third temperature.

5. The method of producing an obliquely-drawn film according to any one of 1 to 4, wherein the first temperature distribution is a distribution in which the temperature monotonically decreases from the retarded side to the preceding side.

6. The method of producing an oblique-drawn film according to any one of 1 to 5, wherein the second temperature distribution is a distribution in which the temperature monotonically increases from the delay side to the preceding side.

7. The slope stretching method according to any one of 1 to 6, wherein the film is stretched in an oblique direction in the oblique stretching zone so that the slow axis is at an angle of about 45 with respect to the width direction of the film Lt; / RTI &gt;

The method for producing an oblique stretched film of the present invention can be used for producing, for example, a? / 4 film applied to an organic EL image display apparatus or a liquid crystal display apparatus.

Ci: Far Earth (Far Earth on the lead)
Co: Fa Earth (Earth on the delay side)
M1: 1st position
M2: 2nd position
M3: Midpoint
T1, T2, T3, T4, T5, T6: Temperature
Z2-2: Inclined stretching zone
Z3: Relaxation zone

Claims (7)

Both ends in the width direction of the film are gripped by a pair of gripping portions to transport the film and the film is transported in the oblique stretching zone on the way so that one wave earth is relatively advanced and the other wave earth is relatively , Wherein the film is stretched in an oblique direction with respect to the width direction, the method comprising the steps of:
Further comprising an alleviating step of alleviating the residual stress of the film by oblique stretching in a relaxation zone in which the film is conveyed in a constant direction after the oblique stretching step,
In the transverse direction of the film, when the side on which one of the pair of waveguide runs first in the oblique stretching is referred to as the leading side and the side in which the other is running in the retarded direction is referred to as the retarded side,
In the oblique stretching zone, a first temperature distribution is formed between the leading side and the retarding side in which the temperature on the preceding side is lower by 1 占 폚 to 15 占 폚 than the temperature on the retarding side,
Wherein the relaxation zone forms a second temperature distribution between the preceding side and the retarded side in which the temperature of the preceding side is higher by 5 占 폚 to 30 占 폚 than the temperature of the retarded side,
Wherein the temperature of the oblique stretching zone is 5 占 폚 to 40 占 폚 higher than the temperature of the relaxation zone. The method according to claim 1, wherein, in the oblique stretching zone, the first temperature distribution is formed in a direction connecting the pair of waveguides when the pair of waveguides reach the oblique stretching end position, respectively And then stretching the film. The method according to claim 1 or 2, wherein in the relaxation zone, the second temperature distribution is formed in a width direction passing through a midpoint of the relaxation zone and perpendicular to the conveyance direction,
Wherein the midpoint is defined by a first position in the middle of a section connecting the pair of waveguides when the pair of waveguides reaches the oblique stretching end position in the oblique stretch zone, And a second position in the middle of the width direction of the outlet. 4. The method according to any one of claims 1 to 3, wherein the temperature of the oblique stretching zone is set so that the temperature of the oblique stretching zone, when the pair of wave earths reaches the oblique stretching end position, Is the temperature of the first location,
Wherein the temperature of the mitigation zone is a temperature of a third position that is the middle of a section connecting the first position and a second position intermediate the width direction of the exit of the mitigation zone,
Wherein the first temperature is higher than the third temperature by 5 占 폚 to 40 占 폚. The method of producing an oblique drawn film according to any one of claims 1 to 4, wherein the first temperature distribution is a distribution in which the temperature monotonously decreases from the delay side to the preceding side. The method of manufacturing an oblique drawn film according to any one of claims 1 to 5, wherein the second temperature distribution is a distribution in which the temperature monotonously increases from the delay side to the preceding side. The film according to any one of claims 1 to 6, wherein the film is stretched in an oblique direction in the oblique stretching zone so that the slow axis is at an angle of about 45 with respect to the width direction of the film A method for producing an oblique stretched film.

Images