JP2009202426A - Method of manufacturing optical resin film and optical film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing an optical resin film which enables the manufacture of a high-quality film by suppressing the generation of gel in a melt extrusion step of a cyclic olefin-based resin, and an optical film obtained by the manufacturing method. <P>SOLUTION: The method of manufacturing the optical resin film is characterized in that the cyclic olefin-based resin is heated and melted in a screw extrusion machine, a melt film forming method for discharging in film shape from a forming die, and an output port pressure of the screw extrusion machine is 0.1-7.0 MPa, and the optical film is obtained by the manufacturing method. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing an optical resin film and an optical film, and in particular, a method for producing an optical resin film using a cyclic olefin resin having a quality suitable for a liquid crystal display device, and an optical film obtained by the production method. About.

  Films produced from cyclic olefin resins (hereinafter also referred to as “cyclic polyolefin films”) are attracting attention as films capable of improving the hygroscopicity and moisture permeability of cellulose triacetate films, and films formed by hot melt film formation and solution film formation. The manufacturing method is being studied. In addition, the cyclic polyolefin film has high optical properties and further changes in optical properties due to temperature changes, and is an optical film such as a retardation film (hereinafter also referred to as “retardation film”). As a development. Such a film is manufactured by heating and melting a cyclic olefin resin with an extruder, discharging the molten resin into a sheet form from a die, cooling it on a cooling drum, and peeling it.

  However, in melt film formation of a cyclic olefin-based resin, a large amount of gel is generated during melt extrusion, which remains on the cyclic polyolefin film, resulting in foreign matter failure.

On the other hand, in order to reduce the gel, a method has been studied in which the temperature of the resin to be fed into the melt extruder is heated, the shear stress generated in the extruder is suppressed, and the generated crosslinked gel is suppressed (patent document). 1). Further, it is disclosed that an optical film having a small haze value and optically homogeneous and excellent in transparency can be obtained by extrusion molding while venting the inside of the extruder through a vent hole (see Patent Document 2). ).
JP 2006-96001 A JP 2006-7715 A

  However, in recent years, higher quality optical films have been demanded, and the production methods of Patent Document 1 and Patent Document 2 have not been sufficiently effective.

  The present invention has been made in view of such circumstances, and a method for producing an optical resin film that can suppress the generation of gel and produce a high-quality film in a melt extrusion process of a cyclic olefin-based resin. The purpose is to provide. Moreover, it aims at providing the optical film manufactured using the manufacturing method.

  In order to achieve the above object, claim 1 of the present invention provides an optical resin film using a melt film-forming method in which a cyclic olefin-based resin is heated and melted with a screw extruder and discharged from a molding die into a film. In the manufacturing method, the screw extruder is a single screw extruder, and the outlet pressure of the screw extruder is 0.1 MPa to 7.0 MPa.

  It is known that the gel generated in the extruder includes a gel in which resins are crosslinked by shearing the resin (shear crosslinking) and a gel in which the resin is crosslinked (oxidative crosslinking). It has been. In particular, in the melt film forming method using an extruder, the gel generated by the shear crosslinking can be suppressed by suppressing the shearing, so that the extrusion conditions are important. According to the first aspect, in the melt film forming method, the outlet pressure of the screw extruder is set to 0.1 MPa to 7.0 MPa, which is lower than the conventional extruder in a range where stable extrusion is possible. Therefore, shear cross-linking can be prevented and gel generation can be suppressed. Moreover, a high quality film can be manufactured. In addition, by reducing the outlet pressure, the occurrence of backflow in the extruder can be suppressed, and the time during which the solution stays in the extruder can be reduced.

  A second aspect of the present invention is characterized in that, in the first aspect, an average residence time from the screw extruder to the forming die is not less than 1 minute and not more than 30 minutes.

  According to claim 2, by setting the average residence time from the screw extruder to the forming die in the above range, shearing in the extruder can be suppressed, so that the generation of gel can be suppressed, and high quality. The film can be manufactured. In the present invention, the “average residence time” is defined by the volume and the flow rate, and can be obtained by the following equation.

(Average residence time) = (Volume from extruder to die [cm ³ ]) / (Discharge amount [cm ³ / min])
In a third aspect according to claim 1 or 2, the groove depth at the groove depth H of the screw flight of the screw extruder is, the groove depth at the resin inlet of the screw extruder H ₁ and the resin outlet part The ratio of H ₂ , H ₁ / H ₂ is greater than 1.5 and less than 2.5.

  According to the third aspect, the groove depth of the screw flight portion allows the stable extrusion and the pressure in the extruder can be suppressed by setting the ratio of the resin outlet portion to the resin outlet portion within a predetermined range. Therefore, shear cross-linking can be prevented and the generation of gel can be suppressed.

  A fourth aspect of the present invention is characterized in that, in any one of the first to third aspects, a resin filling rate in a melt state or a pellet state inside the screw extruder is 70 to 100%.

  According to claim 4, by setting the resin filling rate in the melt state or pellet state inside the screw extruder within the above range, the molten resin can be stably extruded. Quality film can be produced. In the present invention, the “resin filling rate” can be defined by the discharge amount of one screw rotation and the volume corresponding to one pitch of the screw, and can be obtained by the following equation.

(Filling rate) = (Discharge amount of one screw rotation) / (Volume for one screw pitch)
= (Q / N) / (Maximum Q / N)
Q: Discharge amount [cm ³ / min], N: Screw rotation speed [rpm]
Maximum Q / N: Q / N when the extruder is full of resin
Claim 5 has a heating step of heating the cyclic olefin-based resin before charging the screw extruder in claims 1 to 4, and when the glass transition point of the cyclic olefin-based resin is Tg, The temperature T ₀ ° C of the cyclic olefin resin immediately before being introduced into the screw extruder is higher than (Tg-80) ° C and lower than Tg ° C, and the temperature fluctuation range is ± 5 ° C or less.

  According to the fifth aspect of the present invention, there is a heating step of heating the molten resin before feeding it into the extruder, and by setting the temperature of the resin within the above range, the viscosity of the resin can be increased. Since the heat generation due to the friction can be reduced, the generation of gel due to oxidation can be suppressed.

  A sixth aspect of the present invention is characterized in that the oxygen concentration at the inlet of the screw extruder is 0 to 10% in the first to fifth aspects.

  According to the sixth aspect, by setting the oxygen concentration at the inlet of the extruder within the above range, gel generated by oxidative crosslinking can be suppressed, so that a high-quality film can be produced.

  A seventh aspect is characterized in that in any one of the first to sixth aspects, a filter is installed at an outlet of the screw extruder.

  According to the seventh aspect, the gel generated in the extruder can be physically removed by the filter by installing the filter at the outlet of the extruder.

  According to an eighth aspect of the present invention, in order to achieve the above object, the film obtained by the method for producing an optical resin film according to any one of the first to seventh aspects has a haze of 10 when a 10% cyclohexane solution is used. % Or less, an optical film is provided.

  Since the film obtained by the production method of the present invention has a haze of 10% or less when a 10% cyclohexane solution is used, it can be suitably used as an optical film.

  According to the present invention, in the melt-extrusion process, the outlet pressure of the screw extruder is in the range of 0.1 MPa to 7.0 MPa, which enables stable extrusion and can prevent shear crosslinking, so that gel generation is prevented. It can suppress and can manufacture a high quality film.

  Hereinafter, preferred embodiments of a method for producing an optical resin film according to the present invention will be described with reference to the accompanying drawings.

  FIG. 1 shows an example of a schematic configuration of a resin film manufacturing apparatus. As shown in FIG. 1, the manufacturing apparatus 10 mainly includes a film forming process unit 14 that manufactures the resin film 12 before stretching, and a longitudinal stretching process unit 16 that longitudinally stretches the resin film manufactured in the film forming process unit 14. The horizontal stretching process section 18 that performs lateral stretching and the winding process section 20 that winds the stretched resin film 12 are configured.

  In the film forming process section 14, the cyclic olefin-based resin melted by the extruder 22 is discharged from the die 24 into a sheet shape, cast on a rotating cooling drum 26, and rapidly cooled and solidified to obtain the resin film 12. After the resin film 12 is peeled off from the cooling drum 26, the resin film 12 is sequentially sent to the longitudinal stretching process section 16 and the lateral stretching process section 18 to be stretched, and is wound up in a roll shape by the winding process section 20. Thereby, the stretched resin film 12 is manufactured. Hereinafter, details of each process part will be described.

  FIG. 2 shows the configuration of the extruder 22 in the film forming process section 14. As shown in the figure, the extruder 22 is a single screw type extruder and includes a single screw 38 in a cylinder 32. The single screw 38 is configured by attaching a screw blade 36 to a screw shaft 34, is rotatably supported, and is rotated by a motor (not shown).

  A jacket (not shown) is attached to the outer peripheral portion of the cylinder 32 so that the temperature can be controlled to a desired temperature.

  Inside the cylinder 32, in order from the supply port 40 side, a feed part (region indicated by A) for quantitatively transporting the cyclic olefin-based resin supplied from the supply port 40, and a compression part (at B) for kneading and compressing the cyclic olefin-based resin. And a metering portion (region indicated by C) that measures the discharge amount while conveying the kneaded and compressed cyclic olefin resin to the discharge port 42. In the present invention, the resin inlet portion refers to the feed portion A, and the resin outlet portion refers to the metering portion C.

  Further, the outlet pressure of the screw extruder is 0.1 MPa to 7.0 MPa, preferably 0.5 MPa to 4.0 MPa, and more preferably 1.0 MPa to 2.0 MPa. By setting the outlet pressure within the above range, the pressure applied to the molten resin in the screw extruder can be kept low, so that the amount of gel generated by shear crosslinking generated inside the screw can be suppressed. Further, even if the pressure is too low, the density of the resin becomes low, so that the resin cannot be stably extruded. Therefore, the pressure is lowered within a range where stable extrusion is possible, specifically, 0.1 MPa or more.

Moreover, it is preferable to provide a heating means (not shown) for heating the molten resin before feeding it into the screw extruder. By heating the resin before melting, the viscosity of the resin can be quickly reduced, so that the friction time during plasticization can be shortened, thereby suppressing the generation of gel due to shear crosslinking and oxidative crosslinking. it can. On the other hand, if the temperature is too high, the cyclic olefin-based resin adheres to the screw 38 part of the feed part A, and the resin stuck to the screw 38 part of the feed part A is sent to the compression part B. End up. Specifically, the temperature T ₀ ° C. of the resin immediately before being introduced into the screw extruder is, when the glass transition point of the resin is Tg, the range of T ₀ ° C. is larger than (Tg-80) ° C. and smaller than Tg ° C. More preferably, it is larger than (Tg-50) ° C. and smaller than (Tg-5) ° C., more preferably larger than (Tg-20) ° C. and smaller than (Tg-10) ° C. The temperature fluctuation range is preferably within ± 5 ° C.

  It is preferable that the resin filling rate in the melt state and the pellet state in the screw extruder is 70 to 100%. By setting the filling rate within the above range, it is possible to stably extrude, so that generation of gel due to shear crosslinking can be prevented, and a high-quality film can be produced.

  The oxygen concentration at the inlet of the screw extruder is preferably 0 to 10%. By setting the oxygen concentration in the screw extruder within the above range, the amount of gel generated by oxidative crosslinking inside the screw can be suppressed. The oxygen concentration can be adjusted to 0 to 10% by kneading and melting while flowing an inert gas such as nitrogen from the screw extruder inlet into the screw.

  The cyclic olefin-based resin is melted by the extruder 22 configured as described above, and the molten resin is continuously sent from the discharge port 42 through the pipe 23 to the die 24 (see FIG. 1). The pipe 23 is a pipe for communicating the discharge port 42 of the extruder 22 and the die 24, and an aluminum casting heater or a heat medium heater (not shown) is attached to the entire outer periphery of the pipe 23. This aluminum casting or heating medium heater is controlled to be 180 ° C. or higher and 230 ° C. or lower, preferably 190 ° C. or higher and 230 ° C. or lower, more preferably 200 ° C. or higher and 225 ° C. or lower. The temperature control of the pipe 23 is preferably performed by PI control or PID control. The pipe 23 configured as described above can make the temperature fluctuation of the molten resin at the end of the pipe 23 within ± 0.5 ° C. By setting the temperature fluctuation within ± 0.5 ° C, the viscosity of the cyclic olefin resin can be stabilized.

  The average residence time of the cyclic olefin-based resin extruded from the die 24 through the pipe 23 from the extruder 22 is preferably 1 minute or more and 30 minutes or less. More preferably, it is 2 minutes or more and 20 minutes or less, More preferably, it is 3 minutes or more and 10 minutes or less. If the average residence time of the resin exceeds the above range, the resin may be thermally deteriorated in the cylinder 32 to generate a gel or a foreign material, which is not preferable because it causes a foreign material failure in the manufactured resin film 12. . Conversely, if the average residence time is short, the resin is not sufficiently kneaded, which is not preferable.

  Moreover, it is preferable to provide a foreign matter removal filter downstream of the screw extruder. In the present invention, the generation of gel is suppressed by setting the extrusion conditions from the screw extruder, but even when the gel is generated, it can be removed by the foreign matter removing filter.

  The resin film 12 formed using the extruder 22 having the extrusion conditions set as described above has a haze of 10% or less and a yellowness index (YI value) of 10 or less when made into a 10% cyclohexane solution. The characteristic value is as follows.

  Here, the haze value is an index indicating the amount of gel, meaning that the larger the haze, the more gel is present, and the haze value is preferably 10% or less, more preferably 3% or less, More preferably, it is 1% or less.

  The molten resin sent from the extruder 22 to the die 24 via the pipe 23 is extruded from the die 24 into a sheet shape, cast on the cooling drum 26 and cooled and solidified, and the cyclic olefin resin film 12 is formed. Is done. The temperature of the molten resin when extruded from the die 24 is preferably Tg + 70 ° C. or higher and Tg + 120 ° C. or lower in order to prevent thermal deterioration and coloring. Further, the die 24 is preferably formed such that its slit is in a range between the vertical direction and a direction inclined at 45 ° with respect to the rotation direction of the cooling drum 26.

  The cyclic olefin resin film (hereinafter, also referred to as “resin film”) 12 formed in the film forming process section 14 is stretched in the longitudinal stretching process section 16 and the lateral stretching process section 18.

  Below, the extending | stretching process until extending | stretching the resin film 12 formed into a film by the film forming process part 14 and manufacturing the stretched resin film 12 is demonstrated.

  The stretching of the resin film 12 is performed in order to orient the molecules in the resin film 12 and develop in-plane retardation (Re) and thickness direction retardation (Rth).

  As shown in FIG. 1, the resin film 12 is first longitudinally stretched in the longitudinal direction by the longitudinal stretching step 16. In the longitudinal stretching process section 16, after the resin film 12 is preheated, the resin film 12 is heated and wound around two nip rolls 28 and 30. The exit-side nip roll 30 transports the resin film 12 at a transport speed faster than the entrance-side nip roll 28, and thereby the resin film 12 is stretched in the longitudinal direction.

  The preheating temperature in the longitudinal stretching process section 16 is preferably Tg-40 ° C or higher and Tg + 60 ° C or lower, more preferably Tg-20 ° C or higher and Tg + 40 ° C or lower, and further preferably Tg or higher and Tg + 30 ° C or lower. Further, the stretching temperature of the longitudinal stretching step 16 is preferably Tg or more and Tg + 60 ° C. or less, more preferably Tg + 2 ° C. or more and Tg + 40 ° C. or less, and further preferably Tg + 5 ° C. or more and Tg + 30 ° C. or less. The draw ratio in the machine direction is preferably 1.0 to 2.5 times, more preferably 1.1 to 2 times.

  The resin film 12 that has been longitudinally stretched is sent to the lateral stretching step 18 and is laterally stretched in the width direction. For example, a tenter can be suitably used in the lateral stretching step section 18. The tenter grips both ends of the resin film 12 in the width direction with clips, and stretches in the lateral direction. By this transverse stretching, the retardation Rth can be further increased.

  The transverse stretching is preferably carried out using a tenter, and the preferred stretching temperature is preferably Tg or higher and Tg + 60 ° C. or lower, more preferably Tg + 2 ° C. or higher, Tg + 40 ° C. or lower, more preferably Tg + 4 ° C. or higher, Tg + 30 ° C. or lower. . The draw ratio is preferably 1.0 to 2.5 times, more preferably 1.1 to 2.0 times. It is also preferable to relax in the longitudinal direction, the lateral direction, or both after the transverse stretching. Thereby, the distribution of the slow axis in the width direction can be reduced.

  By such stretching, Re is 0 nm to 500 nm, more preferably 10 nm to 400 nm, more preferably 15 nm to 300 nm, and Rth is 0 nm to 500 nm, more preferably 50 nm to 400 nm, and further preferably 70 nm. It is 350 nm or less.

  Of these, those satisfying Re ≦ Rth are more preferable, and those satisfying Re × 2 ≦ Rth are more preferable. In order to realize such a high Rth and low Re, it is preferable to stretch the film that has been longitudinally stretched as described above in the transverse (width) direction. In other words, the difference in orientation between the vertical direction and the horizontal direction becomes the difference in retardation (Re) in the plane, but by stretching in the horizontal direction, which is the orthogonal direction in addition to the vertical direction, the difference in vertical and horizontal orientation is reduced. The surface orientation (Re) can be reduced by reducing the size. On the other hand, since the area magnification increases by stretching in addition to the length, the orientation in the thickness direction increases as the thickness decreases, and Rth can be increased.

  Furthermore, it is preferable that the variation of Re and Rth depending on the location in the width direction and the longitudinal direction is 5% or less, more preferably 4% or less, and still more preferably 3% or less.

The stretched resin film 12 is wound up in a roll shape in the winding process section 20 of FIG. At that time, the winding tension of the resin film 12 is preferably 0.02 kg / mm ² or less. By setting the winding tension in such a range, the stretched resin film 12 can be wound without causing a retardation distribution.

  Next, a resin film suitable for the present invention, a method for forming the resin film 12 before stretching, and a method for forming the resin film will be described.

(Optical film material)
<Cyclic olefin resin>
A cyclic olefin resin is used as the material of the optical resin film of the present invention. The cyclic olefin resin is preferably polymerized from a norbornene compound. This polymerization can be carried out by either ring-opening polymerization or addition polymerization, but addition polymerization is more preferable among cyclic olefin resins.

  Examples of the addition polymerization include those described in Japanese Patent No. 3517471, Japanese Patent No. 3559360, Japanese Patent No. 3867178, Japanese Patent No. 3871721, Japanese Patent No. 3907908, Japanese Patent No. 3945598, Japanese Translation of PCT International Publication No. 2005-527696, Japanese Patent Application Laid-Open No. 2006-28993, and WO 2006-004376. Particularly preferred is that described in Japanese Patent No. 3517471.

  Examples of the ring-opening polymerization include those described in WO98-14499, Japanese Patent 30605532, Japanese Patent 3220478, Japanese Patent 3273046, Japanese Patent 3404027, Japanese Patent 3428176, Japanese Patent 3687231, Japanese Patent 3873934, and Japanese Patent 3912159. Of these, those described in WO98-14499 and Japanese Patent No. 30605532 are preferable.

<Additives>
In these optical resin films, 0 to 20% by mass of alkylphthalylalkyl glycolates, phosphate esters, carboxylic acid esters, and polyhydric alcohols can be added as plasticizers. Phosphite stabilizers (for example, tris (4-methoxy-3,5-diphenyl) phosphite, tris (nonylphenyl) phosphite, tris (2,4-di-t-butylphenyl) phosphite) as a stabilizer, Phenolic stabilizers (eg, 2,6-di-t-butyl-4-methylphenol, 2,2-methylenebis (4-ethyl-6-t-butylphenol), 2,5-di-t-butylhydroquinone, Pentaerythrityltetrakis [.3- (3,5-di-tert-butyl-4-hydroxyphenyl) propiolate, 4,4-thiobis- (6-tert-butyl-3-methylphenol), 1,1, -Bis (4-hydroxyphenyl) cyclohexane, octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propiolate] An epoxy compound and a thioether compound can be added in an amount of 0 to 3% by mass, and an inorganic fine particle such as silica, titania, zirconia, alumina, calcium carbonate, and clay, and an organic fine particle such as cross-linked acrylic and cross-linked styrene can be added as a matting agent. Moreover, ultraviolet absorbers (for example, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2, -methylenebis [4- (1,1,3,3-tetramethylbutyl) -6-[(2H -Benzotriazol-2-yl) phenol]]), an infrared absorber and a retardation modifier are also preferably added.

(Deposition of optical resin film)
<Melt film forming method>
B) Pelletization The resin and additives are preferably mixed and pelletized prior to melt film formation.

  Pelletization can be made by drying the resin and additives, melting at 150 ° C. to 300 ° C. using a twin-screw kneading extruder, and then extruding into a noodle shape in air or water and cutting. Further, pelletization may be performed by an underwater cutting method or the like that is cut while being directly extruded from a die after being melted by an extruder.

  A single screw extruder is used as the extruder. The number of revolutions of the extruder is preferably 10 rpm to 1000 rpm, more preferably 20 rpm to 700 rpm. The extrusion residence time is 10 seconds or more and 10 minutes or less, more preferably 20 seconds to 5 minutes or less.

Preferably, the pellet size is such is preferably 10mm ³ ~1000mm ^3, more preferably 30 mm ³ 500 mm ^3.

B) Kneading and melting It is preferable to reduce moisture in the pellets prior to melt film formation. A preferable drying temperature is 40 to 200 ° C, more preferably 60 to 150 ° C. Thereby, the water content is preferably 1.0% by mass or less, and more preferably 0.1% by mass or less. Drying may be performed in air, nitrogen, or vacuum.

  The dried pellets are fed into the cylinder via the feed port of the extruder, kneaded and melted. The inside of the cylinder is composed of a feed portion (region A), a compression portion (region B), and a metering portion (region C) in this order from the supply port side.

Further, it is preferred that the ratio _H 1 / of _{H 2} groove depth _{H 1} and the groove of the metering section C depth _{H 2} of the feed section A of the screw extruder 22 is less than the greater than 1.5 2.5 in FIG. 2 . More preferably, it is a range larger than 1.8 and smaller than 2.1. By setting H ₁ / H ₂ in the above range, stable extrusion is possible, and the pressure in the extruder can be suppressed, so that shear crosslinking can be prevented and generation of gel can be suppressed. it can.

Furthermore, in the relationship between the cylinder inner diameter D of the extruder 22 and the groove diameter H ₁ of the feed portion A, it is preferable that D / H ₁ is set to 10 or less. Since the resin is transported while being in contact with the screw 38 by increasing the groove diameter H ₁ of the feed portion A so that D / H ₁ is 10 or less, the molten resin is uniformly melted at the feed portion A. Therefore, the uniform molten resin can be stably supplied to the compression portion B.

  And the length of the compression part B of the extruder 22 is 0.5 to 5 times the length of each of the feed part A and the metering part C when the length of the compression part B is 1. It is preferable to set to. In this way, the discharge pressure fluctuation generated by shortening the length of the compression part B shorter than the feed part A and the metering part C and performing rapid compression / melting for a short time, the feed part A before and after the compression part B Absorption can be achieved by increasing the length of the metal ring part C. When the length of the compression part B is 1, when the length of each of the feed part A and the metering part C is less than 0.5 times, there is almost no effect of absorbing discharge pressure fluctuation due to rapid compression and short time, This is because the absorption effect does not change even if it exceeds 5 times.

  The ratio of the cylinder length to the cylinder inner diameter (L / D) of the extruder is preferably 20 to 70, and the cylinder inner diameter is preferably 30 mm to 150 mm. Here, L / D is the ratio of the cylinder length (L) to the cylinder inner diameter (D) in FIG. The extrusion temperature is preferably 190 to 300 ° C. When the temperature in the extruder 22 exceeds 230 ° C., a cooler (not shown) can be provided between the extruder 22 and the die 24. Furthermore, in order to prevent the molten resin due to residual oxygen from being oxidized and generating a gel, it is also preferable to carry out the inside of the extruder in an inert (nitrogen or the like) air flow or while evacuating using a vented extruder.

C) Filtration In order to filter foreign substances such as gel in the molten resin, it is preferable to provide a filtration device incorporating a breaker plate type filtration or a leaf type disk filter. Filtration may be performed in one stage or multistage filtration. The filtration accuracy is preferably 15 μm to 3 μm, and more preferably 10 μm to 3 μm. The filter medium is preferably made of stainless steel. As the structure of the filter medium, a knitted wire, a sintered metal fiber or metal powder (sintered filter medium) can be used, and among them, a sintered filter medium is preferable.

D) Gear pump It is preferable to provide a gear pump between the extruder and the die in order to adjust the outlet pressure of the screw extruder. Thereby, the fluctuation | variation of discharge amount can be reduced and thickness accuracy can also be improved. In addition, the resin pressure fluctuation range in the die can be within ± 1%.

  In order to improve the quantitative supply performance by the gear pump, a method of controlling the pressure before the gear pump to be constant by changing the number of rotations of the screw can also be used.

E) Die Melted by the extruder configured as described above, and the molten resin is continuously fed to the die via a filter and a gear pump as necessary. The die may be any of a T die, a fish tail die, and a hanger coat die. It is also preferable to insert a static mixer immediately before the die in order to increase the uniformity of the resin temperature. The clearance of the T-die exit portion is generally 1.0 to 10 times the film thickness, preferably 1.2 to 5 times.

The die is preferably adjustable in thickness at intervals of 5 to 50 mm. An automatic thickness adjustment die that calculates downstream film thickness and thickness deviation and feeds back the results to die thickness adjustment is also effective. In addition to the single layer film forming apparatus, it is also possible to manufacture using a multilayer film forming apparatus.
F) Cast The molten resin (melt) extruded from the die onto the sheet is cooled and solidified on the casting drum to obtain a film. At this time, it is preferable to shield between the die and the casting drum to suppress the influence of wind.

  When the melt contacts the casting drum, it is preferable to use an electrostatic application method, an air knife method, an air chamber method, a vacuum nozzle method, a touch roll method, etc., to increase the adhesion between the casting drum and the melt, and in particular, the touch roll method is used. preferable. Such an adhesion improving method may be performed on the entire surface of the melt or may be performed on a part thereof.

  The touch roll method is a method of shaping a film surface by placing a touch roll on a cast drum. At this time, the touch roll is preferably not elastic and usually elastic. Thereby, it can suppress that a surface unevenness | corrugation makes below the range of this invention ease by an excessive surface pressure. For this purpose, it is necessary to make the outer cylinder thickness of the roll thinner than that of a normal roll, and the outer wall thickness Z is preferably 0.05 mm to 7.0 mm, more preferably 0.2 mm to 5 mm. 0.0 mm, more preferably 0.3 mm to 3.5 mm. The touch roll may be installed on a metal shaft and a heat medium (fluid) may be passed between them. An elastic layer is provided between the outer cylinder and the metal shaft, and the heat medium (fluid) is filled between the outer cylinders. Can be mentioned. A weaker pressing with a touch roll is preferable because Rth can be reduced more, but if it is too small, the surface roughness of the present invention cannot be achieved. On the other hand, if it is too large, the surface roughness decreases but Rth tends to increase. For this reason, the surface pressure of the touch roll is preferably 0.1 MPa to 5 MPa, more preferably 0.2 MPa to 3 MPa, and still more preferably 0.3 MPa to 2 MPa. Here, the surface pressure is a value obtained by dividing the force pressing the touch roll by the contact area between the optical resin film and the touch roll.

  The temperature of the touch roll is preferably set to 60 ° C to 160 ° C, more preferably 70 ° C to 150 ° C, and still more preferably 80 ° C to 140 ° C. Such temperature control can be achieved by passing a temperature-controlled liquid or gas through these rolls. Thus, what has a temperature control mechanism inside is more preferable.

  The material of the touch roll is preferably a metal, more preferably stainless steel, and the surface is preferably plated. On the other hand, a rubber roll or a metal roll lined with rubber is not preferable because the rubber surface has irregularities and the optical resin film having the surface irregularities cannot be formed.

  The surface of the touch roll and casting roll has an arithmetic average height Ra of 100 nm or less, preferably 50 nm or less, and more preferably 25 nm or less. For example, JP-A-11-314263, JP-A-2002-36332, JP-A-11-235747, WO97 / 28950, JP-A-2004-216717, JP-A-2003-145609 are touch rolls. Can be used.

  More preferably, a plurality of casting drums (rolls) are used for slow cooling (of which the touch roll is arranged so as to touch the first casting roll on the most upstream side (closer to the die)). In general, it is relatively common to use three cooling rolls, but this is not a limitation. The diameter of the roll is preferably 100 mm to 1500 mm, more preferably 150 mm to 1000 mm. The interval between the plurality of rolls is preferably 0.3 mm to 300 mm, more preferably 1 mm to 100 mm, and still more preferably 3 mm to 30 mm. The casting drum is preferably 60 ° C to 160 ° C, more preferably 70 ° C to 150 ° C, still more preferably 80 ° C to 140 ° C.

  Then, it peels off from a casting drum, winds up after passing through a nip roll. The winding speed is preferably 10 m / min to 100 m / min, more preferably 15 m / min to 80 m / min, still more preferably 20 m / min to 70 m / min.

The film forming width is preferably 0.7 m to 3 m, and more preferably 1 m to 2 m. The thickness after film formation (unstretched) is preferably 30 μm to 300 μm, more preferably 40 μm to 250 μm, and still more preferably 60 μm to 200 μm.
G) Trimming, thickening, winding After the film is formed in this way, it is also preferable to trim both ends. The portion cut off by trimming may be crushed and used again as a raw material.

  Further, it is also preferable to perform a thickness increasing process (knurling process) on one or both ends. The height of the unevenness due to the thickness increasing process is preferably 1 μm to 50 μm, more preferably 3 μm to 20 μm. Thickening processing may be convex on both sides or convex on one side. The width of the thickness increasing process is preferably 1 mm to 50 mm, more preferably 3 mm to 30 mm. Extrusion can be performed at room temperature to 300 ° C.

  It is also preferable to attach a laminated film on one side or both sides before winding. The thickness of the laminated film is preferably 5 μm to 100 μm, more preferably 10 μm to 50 μm. The material is not particularly limited, such as polyethylene, polyester, and polypropylene. A preferable winding tension is 2 kg / m width to 50 kg / width, more preferably 5 kg / m width to 30 kg / width.

(Stretching)
The melt-formed resin film is preferably subjected to longitudinal stretching and lateral stretching, and may further be combined with shrinkage treatment. Among these, preferred are those in which transverse stretching is carried out after longitudinal stretching, or those in which transverse stretching and longitudinal shrinkage treatment are combined. The former is suitable for developing high Rth, and the latter is suitable for developing low Rth. When the transverse stretching and the longitudinal shrinkage treatment are performed in combination, the longitudinal shrinkage may be performed during the transverse stretching, may be performed after the transverse stretching, or may be performed both. Further, longitudinal stretching may be combined before or after the transverse stretching or both.

[Longitudinal stretching]
Longitudinal stretching may be performed alone or in combination with lateral stretching. The longitudinal stretching may be performed either before or after the lateral stretching, but is more preferably performed before the lateral stretching. In addition, the longitudinal stretching may be performed in one stage or may be performed in multiple stages.

  Longitudinal stretching can be achieved by installing two pairs of nip rolls and heating the gap between them so that the peripheral speed of the nip roll on the outlet side is higher than the peripheral speed of the nip roll on the inlet side. Under the present circumstances, the expression of the retardation of the thickness direction can be changed by changing the space | interval (l) between nip rolls, and the film width (W) before extending | stretching. When l / W exceeds 2 and 50 or less (long span stretching), Rth can be reduced, and when l / W is 0.01 or more and 0.3 or less (short span stretching), Rth can be increased. In the present invention, any of a long span stretching, a short span stretching, and a region between them (intermediate stretching = 1 / W exceeds 0.3 and 2 or less) may be used. Short span stretching is preferred. Further, when aiming at high Rth, it is more preferable to use short span stretching, and when aiming at low Rth, it is distinguished from long span stretching.

≪Long span stretching≫
As the film is stretched, the film is stretched. At this time, the film is reduced in thickness and width in order to reduce the volume change. Increasing the nip roll interval facilitates shrinkage in the width direction and suppresses thickness reduction (less compression in the thickness direction), suppresses molecular orientation in the film plane and reduces Rth.

  l / W is preferably more than 2 and 50 or less, more preferably 3 to 40, and still more preferably 4 to 20. Such long span stretching may be performed in multiple stages with three or more pairs of nip rolls, as long as the longest aspect ratio is within the above range.

  Such long span stretching may be performed by heating the film between two pairs of nip rolls separated by a predetermined distance. The heating method is a heater heating method (infrared heater, halogen heater, panel heater, etc. above or below the film). Or heating by radiant heat) or a zone heating method (heating in a zone in which hot air or the like is blown and adjusted to a predetermined temperature) may be used.

≪Short span drawing≫
Longitudinal stretching (short span stretching) is performed with l / W exceeding 0.01 and less than 0.3, more preferably 0.03 to 0.25, and even more preferably 0.05 to 0.2. As a result, neck-in (stretching along with stretching and shrinkage in a direction perpendicular to the stretching) can be reduced, and the thickness tends to decrease. As a result, the film is compressed in the thickness direction, and the orientation (plane orientation) in the thickness direction advances and Rth tends to increase.

  Short span stretching can be carried out by changing the conveyance speed between two or more pairs of nip rolls, but normal roll arrangement (as shown in the longitudinal stretching step (108) in FIG. 3 of JP-A-2007-152558), the nip rolls are arranged in parallel. Unlike the arrangement, a gap is generated between the rolls and l / W cannot be reduced, and this can be achieved by arranging two pairs of nip rolls obliquely (shifting the rotation axis of the front and rear nip rolls up and down) (JP 2006-51804 A). 1, the nip rolls are arranged so as to be shifted up and down as shown in Fig. 1. However, in this figure, the nip rolls (22, 24) are drawn wide, but this interval is narrowed so that the nip rolls are close to each other. 1 / W can be reduced with Accordingly, since a heater for heating cannot be installed between the nip rolls, it is preferable to raise the temperature of the film by flowing a heating medium in the nip rolls. Further, it is also preferable to provide a preheating roll in which a heating medium is flowed inside before the entrance side nip roll and heat the film before stretching.

[Horizontal stretching]
The transverse stretching can be performed using a tenter. That is, the film is stretched by holding both ends in the width direction with clips and widening the film in the lateral direction. At this time, the stretching temperature can be controlled by sending wind at a desired temperature into the tenter. The draw ratio here is defined by the following formula.

Stretch ratio (%) = 100 × {(Length after stretching) − (Length before stretching)} / (Length before stretching)
By performing preheating before stretching and post-heat treatment after stretching, the Re and Rth distribution after stretching can be reduced, and variations in orientation angles associated with bowing can be reduced. Either pre-heating or post-heating may be performed, but it is more preferable to perform both. These preheating and post heat treatment are preferably carried out by holding with a clip, that is, carried out continuously with stretching.

  The post-heat treatment is preferably performed at a temperature lower than the stretching temperature by 1 ° C. or higher and 50 ° C. or lower, more preferably 2 ° C. or higher and 40 ° C. or lower, more preferably 3 ° C. or higher and 30 ° C. or lower. More preferably, it is less than the stretching temperature and less than Tg. The preheating time is preferably 1 second or longer and 10 minutes or shorter, more preferably 5 seconds or longer and 4 minutes or shorter, and even more preferably 10 seconds or longer and 2 minutes or shorter. During the heat setting, it is preferable to keep the width of the tenter substantially constant. Here, “substantially” refers to 0% (the same width as the tenter width after stretching) to −10% (shrinking by 10% from the tenter width after stretching = reduced width) of the tenter width after stretching. If the width is wider than the stretched width, residual strain tends to occur in the film, which is not preferable.

  Preheating is a stretching temperature ± 50 ° C, more preferably a stretching temperature ± 35 ° C, and still more preferably a stretching temperature ± 20 ° C. When the bowing after the post heat treatment is convex in the traveling direction, it is preferably lower than the stretching temperature, and when the bowing is concave in the traveling direction, it is preferably higher than the stretching temperature. The preheating time is preferably 1 second or longer and 10 minutes or shorter, more preferably 5 seconds or longer and 4 minutes or shorter, and even more preferably 10 seconds or longer and 2 minutes or shorter. During preheating, it is preferable to keep the width of the tenter substantially constant. Here, “substantially” refers to ± 10% of the width of the unstretched film. Thus, it is more preferable that the heat setting temperature <the stretching temperature <the preheating temperature.

  Such stretching can reduce variations in Re and Rth in the width direction and longitudinal direction, and deviation of the orientation angle from MD (longitudinal direction) or TD (width direction).

[Shrinkage treatment]
Shrinkage treatment is preferably performed during or after stretching, and more preferably, shrinkage relaxation treatment is performed in the longitudinal (longitudinal) direction during or after transverse stretching. Shrinkage treatment can be achieved by lowering the conveying speed in the longitudinal direction on the downstream side from the upstream side, and the amount of shrinkage is preferably 0.1% to 50%, more preferably 1% to 40%, and even more preferably 5%. More than 35%. The amount of contraction referred to here is expressed by the following equation.

Shrinkage (%) = 100 × {(Length before shrinkage treatment) − (Length after shrinkage treatment)} / (Length before shrinkage treatment)
The shrinkage treatment temperature is preferably (Tg-20) ° C to (Tg + 50) ° C, more preferably (Tg-10) ° C to (Tg + 40) ° C, and even more preferably Tg to (Tg + 30) ° C. The shrinkage treatment time is 1 second or more. 15 minutes or less, more preferably 5 seconds or more and 10 minutes or less, and further preferably 10 seconds or more and 5 minutes or less.

  Although the film is stretched in the stretching direction by stretching, the direction perpendicular to the stretching and the thickness direction decrease in order to match the material balance. As the thickness decreases, the film surface is compressed, the molecules are oriented in the surface, and the surface orientation becomes stronger. As a result, Rth increases. However, by performing vertical contraction, thickness reduction can be suppressed and low Rth can be realized. That is, Rth <Re × 1.5, more preferably Rth <Re can be realized by longitudinal contraction. Furthermore, this longitudinal shrinkage also has an effect of suppressing thermal shrinkage of the stretched film, and the amount of thermal shrinkage at 80 ° C. and 100 hr can be reduced to 0.5% or less, more preferably 0.3% or less.

  Such longitudinal contraction can be achieved by, for example, the following method.

≪Shrinkage treatment during stretching≫
Longitudinal shrinkage during transverse stretching can be achieved by stretching in the width direction while slowing the conveying speed of the clip in the tenter from the inlet side to the outlet side, and can be performed using, for example, a biaxial stretching machine. Specifically, transverse stretching and longitudinal shrinkage can be performed simultaneously. For example, Japanese Patent Application Laid-Open No. 2003-211533, Japanese Patent Application Laid-Open No. 6-210726, Japanese Patent Application Laid-Open No. 6-278204, Japanese Patent Application Laid-Open No. 11-77825, Japanese Patent Application Laid-Open No. 2000-24695, Japanese Patent Application Laid-Open No. 2004-195712, Japanese Patent Application Laid-Open No. 2004-142595, An apparatus described in JP-A-2006-22916 can be used. Specifically, a high-performance thin film device (trade name FITZ) manufactured by Ichikin Kogyo Co., Ltd. can be used. This device can arbitrarily set the draw ratio in the machine direction (longitudinal direction of the film = traveling direction of the film) and the draw ratio in the transverse direction (width direction = the direction perpendicular to the proceeding direction of the film). ) Can be arbitrarily set, so that stretching and shrinking can be simultaneously performed under predetermined conditions. In addition, for example, by appropriately combining a rail width control method, a panda graph method, a linear motor control method, etc. that are generally known, the stretching ratio in the width direction is controlled, and the film edge is A biaxial stretching machine or the like that controls the length in the longitudinal direction by changing the interval between the clipped clips can also be used.

≪Shrinkage treatment after stretching≫
Although the following methods I), II), III) and IV) can be mentioned, preferred methods are II) and IV).

  I) The transport speed of the clip in the tenter is made slower than the transport speed of the clip at the entrance of the stretching section during and / or subsequent to transverse stretching (tenter stretching).

  Lateral stretching is performed by widening both ends of the film with clips (tenter stretching). In order to promote shrinkage in the direction perpendicular to stretching and thickness shrinkage, the transport speed of the clips in the tenter during and / or after stretching Is slower than the entrance of the drawing section.

  Among these, it is more preferable to perform longitudinal shrinkage after transverse stretching (when transverse stretching and longitudinal shrinkage are performed simultaneously, stretching and stretching occur simultaneously in the surface and residual strain is likely to occur, and uniformity within the surface is also preferred. Is likely to decrease). Such longitudinal shrinkage after transverse stretching can be achieved, for example, by preparing separate tenter rails for transverse stretching and longitudinal shrinkage so that the speed can be controlled independently. By using the ones described in JP-A-6-278204, JP-A-11-77825, JP-A-2004-195712, JP-A-2006-142595, and the like, by contracting vertically (conveying direction), realizable.

  II) After transverse stretching with a tenter, heat treatment is performed while the conveyance speed on the outlet side is slower than that on the inlet side of the heat treatment zone.

  This method can be achieved by inserting the film into a heat treatment zone provided with two or more pairs of nip rolls after lateral stretching (after exiting from the tenter) and increasing the conveyance speed of the nip roll on the inlet side than the nip roll on the outlet side. In this longitudinal shrinkage zone, film shrinkage occurs in both the longitudinal and transverse directions. Therefore, in order to express the longitudinal shrinkage preferentially, the aspect ratio of the heat treatment zone (the value obtained by dividing the zone length by the inlet side film width) is 0. It is preferably 0.01 to 2, more preferably 0.05 to 1.6, and still more preferably 0.1 to 1.3. The heat treatment zone may be heated by providing a heat treatment zone or a heater between the nip rolls, or the nip roll may be heated to heat the resin film. Such vertical contraction that lowers the conveyance speed on the outlet side is completely different from the heat treatment that only weakens the conveyance tension. In other words, the effect of promoting the neck-in as described above does not occur at all only by lowering the transport tension.

  III) Shrink the resin film in the transport direction on the chuck of the tenter.

  The resin film can be contracted in the longitudinal direction by slipping the resin film on the chuck during or after the transverse stretching. That is, if the resin film is slid in the conveyance (longitudinal) direction on the chuck, it can be contracted longitudinally. Although it is not particularly limited as such a method, for example, it can also be achieved by installing a pulley in the conveying direction in the clip portion of the chuck, and a slipping material (for example, Teflon (registered trademark)) is applied to the resin film gripping surface of the clip. It may be pasted.

IV) Low-tension conveyance between rolls after transverse stretching After transverse stretching (after tenter), when the film is heat-treated at low tension, it tries to shrink in both the longitudinal and transverse directions. At this time, by conveying the film between the rolls, The shrinkage in the horizontal direction can be suppressed by the frictional force between the roll and the film, and the vertical shrinkage can be preferentially expressed.

  In order to obtain the frictional force necessary to suppress the lateral shrinkage of the film, the length that the film is wrapped on the roll (W) and the length that the film is not in contact with the roll between the rolls (G) The ratio (W / G) is preferably 0.01 or more and 3 or less, more preferably 0.03 or more and 1 or less, and still more preferably 0.05 or more and 0.5 or less. Exceeding this range is not preferable because the distance between the rolls becomes long and the frictional force decreases, TD contraction occurs, Re decreases, Rth / Re easily increases, and vertical lines tend to appear. On the other hand, if W / G is less than this range, the residual strain generated by stretching is not eliminated and the thermal dimensional change increases, which is not preferable.

  The number of rolls is preferably 2 or more and 100 or less, more preferably 3 or more and 50 or less, and still more preferably 4 or more and 20 or less. The diameter of the preferable roll is preferably 5 cm to 100 cm, more preferably 10 cm to 80 cm, and still more preferably 15 cm to 60 cm.

  Furthermore, in order to sufficiently obtain the frictional force between the roll and the resin film, the surface roughness (Ra) of the resin film is preferably 0.005 μm or more and 0.04 μm or less, more preferably 0.007 μm or more and 0.035 μm or less, Preferably they are 0.009 micrometer or more and 0.030 micrometer or less. A film having such a surface can be achieved by a touch roll film forming method. By sandwiching the film immediately after casting with a roll having a smooth surface from both sides, higher smoothness can be achieved compared to the case where this film is not used, and the above-mentioned surface roughness can be realized.

  The longitudinal shrinkage treatments of I) and II) may be performed singly or in combination. The shrinking treatment of II) may be performed online after transverse stretching, or may be performed offline after winding after stretching. Preferred is online processing.

[Volatile components during stretching]
In the longitudinal stretching and lateral stretching, the volatile components (solvent, moisture, etc.) are preferably 0.5 wt% or less, more preferably 0.3 wt% or less, and still more preferably 0 wt%, based on the resin. This is because when volatile components are present, shrinkage stress accompanying drying acts and bowing becomes more prominent.

[Film properties after stretching / shrinking]
Thus, it is preferable that the films Re and Rth after the stretching and shrinking treatment satisfy the following formulas (R-1) and (R-2).
Formula (R-1): 0 nm ≦ Re ≦ 300 nm
Formula (R-2): 10 nm ≦ Rth ≦ 300 nm
More preferably, the following formulas (R-3) and (R-4) are satisfied.
Formula (R-3): 20 nm ≦ Re ≦ 200 nm
Formula (R-4): 20 nm ≦ Rth ≦ 200 nm
In this specification, Re (λ) and Rth (λ) represent in-plane retardation and retardation in the thickness direction at a wavelength λ, respectively. Re (λ) is measured with KOBRA 21ADH or WR (manufactured by Oji Scientific Instruments) by making light of wavelength λnm incident in the normal direction of the film. It can be measured by exchanging it with a manual or a program.

  When the film to be measured is represented by a uniaxial or biaxial refractive index ellipsoid, Rth (λ) is calculated by the following method. Rth (λ) is Re (λ), with the in-plane slow axis (determined by KOBRA 21ADH or WR) as the tilt axis (rotating axis) (if there is no slow axis, any in-plane The light of wavelength λ nm is incident from each of the inclined directions in steps of 10 degrees from the normal direction to 50 degrees on one side with respect to the film normal direction (with the direction of the rotation axis as the rotation axis). KOBRA 21ADH or WR calculates based on the measured retardation value, the assumed average refractive index, and the input film thickness value.

  In the above case, in the case of a film having a direction in which the retardation value is zero at a certain tilt angle with the in-plane slow axis from the normal direction as the rotation axis, retardation at a tilt angle larger than the tilt angle. The value is calculated by KOBRA 21ADH or WR after changing the sign to negative. The retardation value is measured from the two inclined directions with the slow axis as the tilt axis (rotation axis) (in the absence of the slow axis, the arbitrary direction in the film plane is the rotation axis). Based on the value, the assumed value of the average refractive index, and the input film thickness value, Rth can also be calculated from the following equations (3) and (4).

  Note that Re (θ) represents a retardation value in a direction inclined by an angle θ from the normal direction. In formula (3), nx represents the refractive index in the slow axis direction in the plane, ny represents the refractive index in the direction perpendicular to nx in the plane, and nz represents the refractive index in the direction perpendicular to nx and ny. .

Rth = ((nx + ny) / 2−nz) × d −−−- type (4)
In the case where the film to be measured cannot be expressed by a uniaxial or biaxial refractive index ellipsoid, that is, a film having no so-called optic axis, Rth (λ) can be calculated by the following method. Rth (λ) is from -50 ° to + 50 ° with respect to the normal direction of the film, with Re (λ) as the slow axis (determined by KOBRA 21ADH or WR) in the plane and the tilt axis (rotation axis) Measured at 11 points by making light of wavelength λ nm incident from each tilted direction in 10 degree steps, and based on the measured retardation value, average refractive index assumed value and input film thickness value, KOBRA 21ADH Or WR is calculated.

  In the above measurement, the assumed value of the average refractive index may be the value in the polymer handbook (JOHN WILEY & SONS, INC) and various optical film catalogs. Those whose average refractive index is not known can be measured with an Abbe refractometer. The average refractive index values of main optical films are exemplified below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), Polystyrene (1.59). By inputting these assumed values of average refractive index and film thickness, KOBRA 21ADH or WR calculates nx, ny, and nz. Nz = (nx−nz) / (nx−ny) is further calculated from the calculated nx, ny, and nz.

  The angle θ formed by the film forming direction (longitudinal direction) and the slow axis of Re of the film is preferably as close to 0 °, + 90 °, or −90 °. That is, the deflection angle from 0 °, 90 °, and −90 ° is preferably within ± 3 °, more preferably within ± 2 °, and further preferably within ± 1 °. θ may be 0 ° (vertical alignment), 90 °, or −90 ° (horizontal alignment), but more preferably is horizontal alignment. In-plane and longitudinal variations of Re and Rth are preferably 0% to 8%, more preferably 0% to 5%, and still more preferably 0% to 3%.

  The change in Re and Rth before and after aging at 80 ° C. for 200 hours is preferably from 0% to 8%, more preferably from 0% to 6%, and even more preferably from 0% to 4%. The longitudinal (MD) and lateral (TD) dimensional changes before and after 80 ° C. for 200 hours are preferably 0% or more and ± 0.5% or less, more preferably 0% or more and ± 0.3% or less, and still more preferably It is 0% or more and ± 0.1% or less.

  The film thickness after stretching is preferably 15 μm to 200 μm, more preferably 20 μm to 120 μm, and still more preferably 25 μm to 80 μm. The thickness unevenness is preferably 0% to 3% in both the longitudinal direction and the width direction, more preferably 0% to 2%, and still more preferably 0% to 1%.

(Film processing)
The resin film thus obtained may be used alone, or may be used in combination with a polarizing plate, a liquid crystal layer or a layer with a controlled refractive index (low reflection layer), A hard coat layer may be provided for use. These can be achieved by the following steps.

≪Surface treatment≫
By performing the surface treatment, adhesion with each functional layer (for example, the undercoat layer and the back layer) can be improved. For example, glow discharge treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, acid or alkali treatment can be used. The glow discharge treatment here includes a low temperature plasma treatment that occurs under a low pressure gas of 10 −3 to 20 Torr (0.13 to 2700 Pa). Further, plasma treatment under atmospheric pressure is also a preferable glow discharge treatment.

  Of these, glow discharge treatment, corona treatment, and flame treatment are preferable, and corona treatment is more preferable.

  It is also preferable to provide an undercoat layer for adhesion to the functional layer. This layer may be coated after the surface treatment or may be coated without the surface treatment. Details of the undercoat layer are described on page 32 of the Japan Society for Invention and Innovation (Public Technical Number 2001-1745, published on March 15, 2001, Japan Institute of Invention). These surface treatment and undercoating processes can be incorporated at the end of the film forming process, can be performed alone, or can be performed in the functional layer application process described later.

≪Function layer grant≫
The functional layer described in detail on pages 32 to 45 of the optical resin film of the present invention in the technical report published by the Japan Society of Invention (Public Technical Number 2001-1745, issued on March 15, 2001, Japan Society of Invention). Are preferably combined. Among these, application of a polarizing layer (polarizing plate), application of an optically anisotropic layer (optical compensation layer), and application of an antireflection layer (antireflection film) are preferable.

(Optically anisotropic layer)
The optically anisotropic layer is preferably designed so as to compensate for the liquid crystalline compound in the liquid crystal cell in the black display of the liquid crystal display device. The alignment state of the liquid crystal compound in the liquid crystal cell in black display varies depending on the mode of the liquid crystal display device. The alignment state of the liquid crystal compound in this liquid crystal cell is described in IDW'00, P411 to 414 of FMC7-2, and the like.

  The optically anisotropic layer is formed directly from the liquid crystalline compound on the support or from the liquid crystalline compound via an alignment film. The alignment film preferably has a thickness of 10 μm or less.

  The liquid crystalline compound used for the optically anisotropic layer includes a rod-like liquid crystalline compound and a discotic liquid crystalline compound. The rod-like liquid crystal compound and the discotic liquid crystal compound may be a high-molecular liquid crystal or a low-molecular liquid crystal, and further include those in which the low-molecular liquid crystal is cross-linked and no longer exhibits liquid crystallinity. The optically anisotropic layer can be formed by applying a liquid crystal compound and, if necessary, a coating liquid containing a polymerizable initiator and optional components on the alignment film. A preferred example of the alignment film of the present invention is described in JP-A-8-338913.

[Bar-shaped liquid crystalline compound]
Examples of rod-like liquid crystalline compounds include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines. , Phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used.

  The rod-like liquid crystalline compound includes a metal complex. Moreover, the liquid crystal polymer which contains a rod-shaped liquid crystalline compound in a repeating unit can also be used as a rod-shaped liquid crystalline compound. That is, the rod-like liquid crystalline compound may be bonded to a (liquid crystal) polymer.

  Regarding rod-like liquid crystalline compounds, for example, Quarterly Chemical Review Vol. 22, Liquid Crystal Chemistry (1994), Chapter 4, Chapter 7 and Chapter 11 of the Chemical Society of Japan and Liquid Crystal Device Handbook, Japan Society for the Promotion of Science, 142nd Committee The one described in Chapter 3 of the edition can be adopted.

  The birefringence of the rod-like liquid crystalline compound is preferably in the range of 0.001 to 0.7.

  The rod-like liquid crystalline compound preferably has a polymerizable group in order to fix its alignment state. The polymerizable group is preferably an unsaturated polymerizable group or an epoxy group, more preferably an unsaturated polymerizable group, and most preferably an ethylenically unsaturated polymerizable group.

[Discotic liquid crystalline compounds]
Examples of discotic liquid crystalline compounds include C.I. Benzene derivatives described in a research report of Destrade et al. (Mol. Cryst. 71, 111 (1981)), C.I. Destrode et al. (Mol. Cryst. 122, 141 (1985), Physics lett, A, 78, 82 (1990)) described in The cyclohexane derivatives described in the research report of Kohne et al. (Angew. Chem. 96, 70 (1984)) and M.M. Lehn et al. (JCS, Chem. Commun., 1794 (1985)), J.C. Azacrown-type and phenylacetylene-type macrocycles described in the research report of Zhang et al. (J. Am. Chem. Soc. 116, 2655 (1994)) are included.

  The discotic liquid crystalline compound also includes a compound having a structure in which a linear alkyl group, an alkoxy group, and a substituted benzoyloxy group are radially substituted as a side chain of the mother nucleus with respect to the mother nucleus at the center of the molecule. The molecule or the assembly of molecules is preferably a compound having rotational symmetry and imparting a certain orientation. The optically anisotropic layer formed from the discotic liquid crystalline compound does not necessarily require that the compound finally contained in the optically anisotropic layer is a discotic liquid crystalline compound. Also included are compounds having a group that reacts with heat or light and, as a result, polymerized or cross-linked by reaction with heat or light, resulting in a high molecular weight and loss of liquid crystallinity. Preferred examples of the discotic liquid crystalline compound are described in JP-A-8-50206. Moreover, about superposition | polymerization of a discotic liquid crystalline compound, Unexamined-Japanese-Patent No. 8-27284 has description.

  In order to fix the discotic liquid crystalline compound by polymerization, it is necessary to bond a polymerizable group as a substituent to the discotic core of the discotic liquid crystalline compound. However, when the polymerizable group is directly connected to the disc-shaped core, it becomes difficult to maintain the orientation state in the polymerization reaction. Therefore, a linking group is introduced between the discotic core and the polymerizable group. Therefore, the discotic liquid crystalline compound having a polymerizable group is preferably a compound represented by the following formula (5).

General formula (5)
D (-LQ) _r
(In General Formula (5), D is a discotic core, L is a divalent linking group, Q is a polymerizable group, and r is an integer of 4 to 12.)
An example of the disk-shaped core (D) is shown below. In each of the following examples, LQ (or QL) means a combination of a divalent linking group (L) and polymerizability (Q).

  In the general formula (5), the divalent linking group (L) is selected from the group consisting of an alkylene group, an alkenylene group, an arylene group, —CO—, —NH—, —O—, —S—, and combinations thereof. It is preferable that it is a bivalent coupling group. The divalent linking group (L) is a divalent combination of at least two divalent groups selected from the group consisting of an alkylene group, an arylene group, -CO-, -NH-, -O-, and -S-. More preferably, it is a linking group. The divalent linking group (L) is most preferably a divalent linking group in which at least two divalent groups selected from the group consisting of an alkylene group, an arylene group, -CO- and -O- are combined. . The alkylene group preferably has 1 to 12 carbon atoms. The alkenylene group preferably has 2 to 12 carbon atoms. The number of carbon atoms in the arylene group is preferably 6-10.

Examples of the divalent linking group (L) are shown below. The left side is bonded to the discotic core (D), and the right side is bonded to the polymerizable group (Q). AL represents an alkylene group or an alkenylene group, and AR represents an arylene group. The alkylene group, alkenylene group and arylene group may have a substituent (eg, an alkyl group).
L1: -AL-CO-O-AL-,
L2: -AL-CO-O-AL-O-,
L3: -AL-CO-O-AL-O-AL-,
L4: -AL-CO-O-AL-O-CO-,
L5: -CO-AR-O-AL-,
L6: -CO-AR-O-AL-O-,
L7: -CO-AR-O-AL-O-CO-,
L8: -CO-NH-AL-,
L9: -NH-AL-O-,
L10: -NH-AL-O-CO-,
L11: -O-AL-,
L12: -O-AL-O-,
L13: -O-AL-O-CO-,
L14: -O-AL-O-CO-NH-AL-,
L15: -O-AL-S-AL-,
L16: -O-CO-AL-AR-O-AL-O-CO-,
L17: -O-CO-AR-O-AL-CO-,
L18: -O-CO-AR-O-AL-O-CO-,
L19: -O-CO-AR-O-AL-O-AL-O-CO-,
L20: -O-CO-AR-O-AL-O-AL-O-AL-O-CO-,
L21: -S-AL-,
L22: -S-AL-O-,
L23: -S-AL-O-CO-,
L24: -S-AL-S-AL-,
L25: -S-AR-AL-.

  The polymerizable group (Q) of the general formula (5) is determined according to the type of polymerization reaction. Examples of the polymerizable group (Q) are shown below.

  The polymerizable group (Q) is preferably an unsaturated polymerizable group (Q1, Q2, Q3, Q7, Q8, Q15, Q16, Q17) or an epoxy group (Q6, Q18). More preferably, it is most preferably an ethylenically unsaturated polymerizable group (Q1, Q7, Q8, Q15, Q16, Q17). A specific value of r is determined according to the type of the disk-shaped core (D). In addition, although the combination of several L and Q may differ, it is preferable that it is the same.

  In the hybrid alignment, the angle between the major axis (disk surface) of the discotic liquid crystalline compound and the surface of the support, that is, the inclination angle is in the direction of the depth of the optically anisotropic layer (that is, perpendicular to the transparent support). And it increases or decreases as the distance from the plane of the polarizing film increases. The angle preferably increases with increasing distance. Further, the change in the tilt angle can be continuous increase, continuous decrease, intermittent increase, intermittent decrease, change including continuous increase and continuous decrease, or intermittent change including increase and decrease. . The intermittent change includes a region where the inclination angle does not change in the middle of the thickness direction. Even if a region where the angle does not change is included, it may be increased or decreased as a whole. However, it is preferred that the tilt angle changes continuously.

  The average direction of the major axis (disk surface) of the discotic liquid crystalline compound (average of the major axis direction of each molecule) is generally selected by selecting the discotic liquid crystalline compound or the material of the alignment film, or selecting the rubbing treatment method. By doing so, it can be adjusted. The major axis (disk surface) direction of the discotic liquid crystalline compound on the surface side (air side) is generally adjusted by selecting the type of additive used together with the discotic liquid crystalline compound or the discotic liquid crystalline compound. be able to.

  Examples of the additive used together with the discotic liquid crystalline compound include a plasticizer, a surfactant, a polymerizable monomer and a polymer. The degree of change in the orientation direction of the major axis can also be adjusted by selecting liquid crystalline molecules and additives as described above.

  The plasticizer, surfactant and polymerizable monomer used together with the discotic liquid crystalline compound are compatible with the discotic liquid crystalline compound, and can change the tilt angle of the discotic liquid crystalline compound or change the orientation. It is preferable not to inhibit. Among the additive components, addition of a polymerizable monomer (eg, a compound having a vinyl group, a vinyloxy group, an acryloyl group and a methacryloyl group) is preferable. The amount of the compound added is generally in the range of 1 to 50% by mass and preferably in the range of 5 to 30% by mass with respect to the discotic liquid crystalline compound. In addition, when a monomer having 4 or more polymerizable reactive functional groups is mixed and used, adhesion between the alignment film and the optically anisotropic layer can be improved.

  The optically anisotropic layer may contain a polymer together with the discotic liquid crystalline compound. The polymer preferably has a certain degree of compatibility with the discotic liquid crystalline compound and can change the tilt angle of the discotic liquid crystalline compound. A cellulose ester can be mentioned as an example of a polymer. Preferable examples of the cellulose ester include cellulose acetate, cellulose acetate propionate, hydroxypropyl cellulose and cellulose acetate butyrate. The addition amount of the polymer is preferably in the range of 0.1 to 10% by mass with respect to the discotic liquid crystalline compound so as not to inhibit the orientation of the discotic liquid crystalline compound, and 0.1 to 8% by mass. More preferably, it is in the range of 0.1 to 5% by mass. The discotic nematic liquid crystal phase-solid phase transition temperature of the discotic liquid crystalline compound is preferably 70 to 300 ° C, more preferably 70 to 170 ° C.

[Fixing the alignment state of liquid crystalline molecules]
The aligned liquid crystal molecules can be fixed while maintaining the alignment state. The immobilization is preferably performed by a polymerization reaction. The polymerization reaction includes a thermal polymerization reaction using a thermal polymerization initiator and a photopolymerization reaction using a photopolymerization initiator. A photopolymerization reaction is preferred.

  Examples of photopolymerization initiators include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ethers (described in US Pat. No. 2,448,828), α-hydrocarbon substituted aromatic acyloin compounds ( U.S. Pat. No. 2,722,512), a polynuclear quinone compound (described in U.S. Pat. Nos. 3,046,127 and 2,951,758), a combination of triarylimidazole dimer and p-aminophenyl ketone (described in U.S. Pat. No. 3,549,367), acridine, and Phenazine compounds (described in JP-A-60-105667 and US Pat. No. 4,239,850) and oxadiazole compounds (described in US Pat. No. 4,221,970) are included.

  The amount of the photopolymerization initiator used is preferably in the range of 0.01 to 20% by mass, more preferably in the range of 0.5 to 5% by mass, based on the solid content of the coating solution.

  It is preferable to use ultraviolet rays for light irradiation for polymerization of liquid crystalline molecules.

The irradiation energy ^is preferably in the range of ^{20mJ / cm 2 ~50J / cm 2} , more preferably in the range of ^{20mJ / cm 2 ~5000mJ / cm 2} , a range of 100mJ / cm ² ~800mJ / cm 2 More preferably. In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions.

  A protective layer may be provided on the optically anisotropic layer.

  The optically anisotropic layer is prepared by preparing a coating solution containing at least one of the liquid crystalline compounds and, optionally, an additive such as a polymerizable initiator and a fluorine-based polymer, and applying the coating solution to the alignment film surface. It can be formed by drying.

  Examples of the fluorine-based compound include conventionally known compounds. Specific examples include the fluorine-based compounds described in paragraphs [0028] to [0056] of JP-A-2001-330725. It is done.

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

  When producing an optical compensation film with high uniformity, the surface tension of the coating solution is preferably 25 mN / m or less, and more preferably 22 mN / m or less.

  The coating liquid can be applied by a known method (eg, extrusion coating method, direct gravure coating method, reverse gravure coating method, die coating method).

[Polarizer]
(Polarizing film)
The polarizing film that can be used in the polarizing plate of the present invention is preferably a coating type polarizing film typified by Optiva, or a polarizing film comprising a binder and iodine or a dichroic dye.

  Iodine and dichroic dye in the polarizing film exhibit deflection performance by being oriented in the binder. It is preferable that the iodine and the dichroic dye are aligned along the binder molecule, or the dichroic dye is aligned in one direction by self-assembly such as liquid crystal.

  A general-purpose polarizer can be prepared, for example, by immersing a stretched polymer in a solution of iodine or dichroic dye in a bath and allowing the iodine or dichroic dye to penetrate into the binder. it can.

  In general-purpose polarizing films, iodine or dichroic dye is distributed about 4 μm (about 8 μm on both sides) from the polymer surface, and a thickness of at least 10 μm is necessary to obtain sufficient polarization performance. The penetrability can be controlled by the solution concentration of iodine or dichroic dye, the temperature of the bath, and the immersion time.

  As described above, the lower limit of the binder thickness is preferably 10 μm. On the other hand, the upper limit of the thickness is not particularly limited, but the thinner the better, from the viewpoint of the light leakage phenomenon that occurs when the polarizing plate is used in a liquid crystal display device. Currently, it is preferably a general-purpose polarizing plate (about 30 μm) or less, preferably 25 μm or less, and more preferably 20 μm or less. When it is 20 μm or less, the light leakage phenomenon is not observed in a 17-inch liquid crystal display device.

  The binder of the polarizing film may be cross-linked. As the crosslinked binder, a polymer that can be crosslinked per se can be used. A polarizing film can be formed by reacting a polymer having a functional group or a binder obtained by introducing a functional group into a polymer between the binders by light, heat, or pH change.

  Moreover, you may introduce | transduce a crosslinked structure into a polymer with a crosslinking agent. It can be formed by cross-linking between binders by introducing a bonding group derived from the cross-linking agent between binders using a cross-linking agent which is a compound having high reaction activity.

  Crosslinking is generally carried out by applying a coating solution containing a polymer or a mixture of a polymer and a crosslinking agent on a transparent support and then heating. Since it is only necessary to ensure durability at the stage of the final product, the cross-linking treatment may be performed at any stage until the final polarizing plate is obtained.

  As the binder for the polarizing film, either a polymer that can be crosslinked by itself or a polymer that is crosslinked by a crosslinking agent can be used. Examples of polymers include polymethyl methacrylate, polyacrylic acid, polymethacrylic acid, polystyrene, gelatin, polyvinyl alcohol, modified polyvinyl alcohol, poly (N-methylolacrylamide), polyvinyltoluene, chlorosulfonated polyethylene, nitrocellulose, chlorinated Polyolefin (eg, polyvinyl chloride), polyester, polyimide, polyvinyl acetate, polyethylene, carboxymethyl cellulose, polypropylene, polycarbonate and copolymers thereof (eg, acrylic acid / methacrylic acid polymer, styrene / maleimide polymer, styrene / vinyl) Toluene polymer, vinyl acetate / vinyl chloride polymer, ethylene / vinyl acetate polymer). Water-soluble polymers (eg, poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol and modified polyvinyl alcohol) are preferred, gelatin, polyvinyl alcohol and modified polyvinyl alcohol are more preferred, and polyvinyl alcohol and modified polyvinyl alcohol are most preferred. .

  The saponification degree of polyvinyl alcohol and modified polyvinyl alcohol is preferably 70 to 100%, more preferably 80 to 100%, and most preferably 95 to 100%. As for the polymerization degree of polyvinyl alcohol, 100-5000 are preferable.

The modified polyvinyl alcohol is obtained by introducing a modifying group into polyvinyl alcohol by copolymerization modification, chain transfer modification or block polymerization modification. In the copolymerization modification, —COONa, —Si (OH) ₃ , N (CH ₃ ) ₃ .Cl, C ₉ H ₁₉ COO—, —SO ₃ Na, —C ₁₂ H ₂₅ may be introduced as a modifying group. it can. In chain transfer modification,
COONa, _-SH, may be introduced _-SC 12 _{H 25.} The degree of polymerization of the modified polyvinyl alcohol is preferably 100 to 3000. The modified polyvinyl alcohol is described in JP-A-8-338913, JP-A-9-152509 and JP-A-9-316127.

  Unmodified polyvinyl alcohol and alkylthio-modified polyvinyl alcohol having a saponification degree of 85 to 95% are particularly preferable.

  Two or more kinds of polyvinyl alcohol and modified polyvinyl alcohol may be used in combination.

  When a large amount of the crosslinking agent for the binder is added, the heat and humidity resistance of the polarizing film can be improved. However, when 50 mass% or more of a crosslinking agent is added to the binder, the orientation of iodine or the dichroic dye is lowered. 0.1-20 mass% is preferable with respect to a binder, and, as for the addition amount of a crosslinking agent, 0.5-15 mass% is more preferable.

  The binder contains some crosslinking agent that has not reacted even after the crosslinking reaction has been completed. However, the amount of the remaining crosslinking agent is preferably 1.0% by mass or less in the binder, and more preferably 0.5% by mass or less. When the crosslinking agent is contained in the binder layer in an amount exceeding 1.0% by mass, there may be a problem in durability. That is, when a polarizing film having a large amount of residual crosslinking agent is incorporated in a liquid crystal display device and used for a long time or left in a high-temperature and high-humidity atmosphere for a long time, the degree of polarization may decrease.

  The crosslinking agent is described in US Reissue Patent 23297. Boron compounds (eg, boric acid, borax) can also be used as a crosslinking agent.

  As the dichroic dye, an azo dye, stilbene dye, pyrazolone dye, triphenylmethane dye, quinoline dye, oxazine dye, thiazine dye or anthraquinone dye is used. The dichroic dye is preferably water-soluble. The dichroic dye preferably has a hydrophilic substituent (eg, sulfo, amino, hydroxyl).

  Examples of dichroic dyes include C.I. I. Direct Yellow 12, C.I. I. Direct Orange 39, C.I. I. Direct Orange 72, C.I. I. Direct Red 39, C.I. I. Direct Red 79, C.I. I. Direct Red 81, C.I. I. Direct Red 83, C.I. I. Direct Red 89, C.I. I. Direct Violet 48, C.I. I. Direct Blue 67, C.I. I. Direct Blue 90, C.I. I. Direct Green 59, C.I. I. Acid Red 37 is included. As for the dichroic dyes, those described in JP-A-1-161202, 1-172906, 1-172907, 1-183602, 1-248105, 1-265205, 7-261024 are used. There are descriptions in each publication. The dichroic dye is used as a free acid or an alkali metal salt, ammonium salt or amine salt. By blending two or more kinds of dichroic dyes, polarizing films having various hues can be produced. A polarizing film using a compound (pigment) that exhibits a black color when the polarization axes are orthogonal to each other, or a polarizing film or a polarizing plate that is blended with various dichroic molecules so as to exhibit a black color, have both a single-plate transmittance and a polarizing coefficient. It is excellent and preferable.

  In order to increase the contrast ratio of the liquid crystal display device, the transmittance of the polarizing plate is preferably higher and the degree of polarization is preferably higher. The transmittance of the polarizing plate is preferably in the range of 30 to 50%, more preferably in the range of 35 to 50%, and in the range of 40 to 50% in the light having a wavelength of 550 nm (of the polarizing plate). Most preferably, the maximum value of the single plate transmittance is 50%. The degree of polarization is preferably in the range of 90 to 100%, more preferably in the range of 95 to 100%, and most preferably in the range of 99 to 100% in light having a wavelength of 550 nm.

  It is also possible to arrange the polarizing film and the optically anisotropic layer, or the polarizing film and the alignment film via an adhesive. As the adhesive, a polyvinyl alcohol resin (including a modified polyvinyl alcohol with an acetoacetyl group, a sulfonic acid group, a carboxyl group, or an oxyalkylene group) or an aqueous boron compound solution can be used. Of these, polyvinyl alcohol resins are preferred. The thickness of the adhesive layer is preferably in the range of 0.01 to 10 μm after drying, and particularly preferably in the range of 0.05 to 5 μm.

(Manufacture of polarizing plates)
From the viewpoint of yield, the polarizing film is stretched at an angle of 10 to 80 degrees with respect to the longitudinal direction (MD direction) of the polarizing film (stretching method) or rubbed (rubbing method). It is preferable to dye with a dichroic dye. The tilt angle is preferably stretched so as to match the angle formed between the transmission axis of the two polarizing plates bonded to both sides of the liquid crystal cell constituting the LCD and the vertical or horizontal direction of the liquid crystal cell.

  A normal inclination angle is 45 degrees. Recently, however, devices that are not necessarily 45 degrees have been developed in transmissive, reflective, and transflective LCDs, and it is preferable that the stretching direction can be arbitrarily adjusted in accordance with the design of the LCD.

  In the stretching method, the stretching ratio is preferably 2.5 to 30.0 times, and more preferably 3.0 to 10.0 times. Stretching can be performed by dry stretching in air. Moreover, you may implement wet extending | stretching in the state immersed in water. The stretch ratio of dry stretching is preferably 2.5 to 5.0 times, and the stretch ratio of wet stretching is preferably 3.0 to 10.0 times. The stretching step may be performed in several steps including oblique stretching. By dividing into several times, it is possible to stretch more uniformly even at high magnification. Before the oblique stretching, a slight stretching (a degree to prevent shrinkage in the width direction) may be performed horizontally or vertically. Note that. The stretching ratio here is expressed by the ratio (L ′ / L) of the length (L) before stretching and the length (L ′) after stretching, with a mark on the film before stretching. The

  Stretching can be performed by performing tenter stretching in biaxial stretching in different steps. The biaxial stretching is the same as the stretching method performed in normal film formation. In biaxial stretching, stretching is performed at different speeds on the left and right, so that the thickness of the binder film before stretching needs to be different on the left and right. In casting film formation, the flow rate of the binder solution can be differentiated between the left and right sides by tapering the die.

  As described above, a binder film that is obliquely stretched by 10 to 80 degrees with respect to the MD direction of the polarizing film is produced.

  In the rubbing method, a rubbing treatment method widely adopted as a liquid crystal alignment treatment process of LCD can be applied. That is, orientation is obtained by rubbing the surface of the film in a certain direction using paper, gauze, felt, rubber, nylon, or polyester fiber. In general, it is carried out by rubbing several times using a cloth in which fibers having a uniform length and thickness are planted on average. It is preferable to carry out using a rubbing roll in which the roundness, cylindricity, and deflection (eccentricity) of the roll itself are all 30 μm or less. The film wrap angle on the rubbing roll is preferably 0.1 to 90 degrees. However, as described in JP-A-8-160430, a stable rubbing treatment can be obtained by winding 360 degrees or more.

  When rubbing a long film, the film is preferably transported at a speed of 1 to 100 m / min in a constant tension state by a transport device. The rubbing roll is preferably rotatable in the horizontal direction with respect to the film traveling direction for setting an arbitrary rubbing angle. It is preferable to select an appropriate rubbing angle in the range of 0 to 60 degrees. When used in a liquid crystal display device, 40 to 50 degrees is preferable. 45 degrees is particularly preferable.

[Liquid Crystal Display]
The optical film manufactured by the method for manufacturing an optical resin film of the present invention can be used in various modes of liquid crystal display devices. Hereinafter, preferred forms of the optically anisotropic layer in each liquid crystal mode will be described.

(TN mode liquid crystal display)
The TN mode liquid crystal cell is most frequently used as a color TFT liquid crystal display device, and is described in many documents.

  The alignment state in the liquid crystal cell in the TN mode black display is an alignment state in which a rod-like liquid crystalline molecule rises at the center of the cell and the rod-like liquid crystalline compound lies in the vicinity of the cell substrate.

  The rod-like liquid crystalline compound in the center of the cell is compensated with a discotic liquid crystalline compound of the homeotropic orientation (horizontal orientation in which the disk surface is lying) or a (transparent) support, and the rod-like liquid crystalline property in the vicinity of the cell substrate The compound can be compensated with a discotic liquid crystalline compound having a hybrid alignment (an alignment in which the inclination of the major axis changes with the distance from the polarizing film).

  In addition, the rod-like liquid crystalline compound at the center of the cell is compensated with a rod-like liquid crystalline compound having a homogeneous orientation (horizontal orientation in which the major axis lies) or a (transparent) support, and the rod-like liquid crystalline property in the vicinity of the cell substrate is compensated. The compound can be compensated with a discotic liquid crystalline compound having a hybrid alignment.

  The homeotropic alignment liquid crystal compound is aligned in a state where the angle between the average alignment direction of the major axis of the liquid crystal compound and the plane of the polarizing film is 85 to 95 degrees.

  The liquid crystal compound of homogeneous alignment is aligned with the angle between the average alignment direction of the major axis of the liquid crystal compound and the plane of the polarizing film being less than 5 degrees.

  In the hybrid alignment liquid crystalline compound, the angle between the long axis average alignment direction of the liquid crystalline compound and the plane of the polarizing film is preferably 15 degrees or more, and more preferably 15 degrees to 85 degrees.

  Optically anisotropic layer in which support or discotic liquid crystalline compound is homeotropically oriented, optically anisotropic layer in which rod-like liquid crystalline compound is homogeneously oriented, and homeotropically oriented discotic liquid crystalline compound And an optically anisotropic layer made of a mixture of rod-like liquid crystalline compounds that are homogeneously oriented have an Rth retardation value of 40 nm to 200 nm, and an Re retardation value of 0 to 70 nm.

  Regarding the discotic liquid crystal compound layer having homeotropic alignment (horizontal alignment) and the rod-like liquid crystal compound layer having homogeneous alignment (horizontal alignment), Japanese Patent Laid-Open Nos. 12-304931 and 12-304932 describe them. Are listed. The discotic liquid crystal compound layer having a hybrid orientation is described in JP-A-8-50206.

(OCB mode liquid crystal display)
The OCB mode liquid crystal cell is a bend alignment mode liquid crystal cell in which a rod-like liquid crystal compound is aligned in a substantially opposite direction (symmetrically) between an upper portion and a lower portion of the liquid crystal cell. Liquid crystal display devices using a bend alignment mode liquid crystal cell are disclosed in US Pat. Nos. 4,583,825 and 5,410,422. Since the rod-like liquid crystal compounds are symmetrically aligned at the upper and lower portions of the liquid crystal cell, the bend alignment mode liquid crystal cell has a self-optical compensation function. Therefore, this liquid crystal mode is called an OCB (Optically Compensatory Bend) liquid crystal mode.

  Similarly to the TN mode, the liquid crystal cell in the OCB mode is in a black display, and the alignment state in the liquid crystal cell is such that the rod-like liquid crystal compound rises at the center of the cell and the rod-like liquid crystal compound lies in the vicinity of the cell substrate. .

  Since the TN mode and the alignment of the liquid crystal are the same in black display, the preferred mode is the same for the TN mode. However, since the OCB mode has a larger range in which the liquid crystal compound has risen at the center of the cell than the TN mode, an optically anisotropic layer in which the discotic liquid crystal compound is homeotropically aligned or a rod-like liquid crystal It is necessary to slightly adjust the retardation value of the optically anisotropic layer in which the functional compound is homogeneously oriented. Specifically, the optically anisotropic layer in which the discotic liquid crystalline compound on the support is homeotropically oriented, or the optically anisotropic layer in which the rod-like liquid crystalline compound is homogeneously oriented has an Rth retardation value. Is preferably 150 nm to 500 nm, and the Re retardation value is preferably 20 to 70 nm.

(VA mode liquid crystal display device)
In the VA mode liquid crystal cell, the rod-like liquid crystalline compound is aligned substantially vertically when no voltage is applied.

  The VA mode liquid crystal cell includes (1) a narrowly defined VA mode liquid crystal cell in which a rod-like liquid crystal compound is aligned substantially vertically when no voltage is applied, and is substantially horizontally aligned when a voltage is applied (Japanese Patent Laid-Open No. 2). 176625 (in Japanese Patent Publication No. 176625), and (2) a liquid crystal cell (SID97, Digest of tech. Papers (Proceedings) 28 (1997) 845 in which the VA mode is converted into a multi-domain (in MVA mode) for widening the viewing angle ), (3) A liquid crystal cell in a mode (n-ASM mode) in which a rod-like liquid crystalline compound is substantially vertically aligned when no voltage is applied and twisted multi-domain alignment is applied when a voltage is applied (Preliminary Collection 58-59 of the Japan Liquid Crystal Society) (1998)) and (4) SURVAVAL mode liquid crystal cells (announced at LCD International 98).

  In the black display of the VA mode liquid crystal display device, most of the rod-like liquid crystalline compounds in the liquid crystal cell are in a standing state, so that the optically anisotropic layer in which the discotic liquid crystalline compounds are homeotropically aligned, Alternatively, the liquid crystalline compound is compensated by an optically anisotropic layer in which the rod-like liquid crystalline compound is homogeneously oriented, and separately, the rod-like liquid crystalline compound is homogeneously oriented, and the average orientation direction of the major axis of the rod-like liquid crystalline compound and the polarizing film It is preferable to compensate the viewing angle dependency of the polarizing plate with an optically anisotropic layer having an angle with respect to the transmission axis direction of less than 5 degrees.

  The optically anisotropic layer in which the support or the discotic liquid crystalline compound is homeotropically oriented, or the optically anisotropic layer in which the rod-like liquid crystalline compound is homogeneously oriented has an Rth retardation value of 150 nm to 500 nm. The Re retardation value is preferably 20 to 70 nm.

(Other liquid crystal display devices)
The ECB mode and STN mode liquid crystal display devices can be optically compensated in the same way as described above.

(C) Application of an antireflection layer (antireflection film)
An antireflection layer may be provided on the optical resin film of the present invention. The antireflection film generally has a low refractive index layer which is also an antifouling layer, and at least one layer having a higher refractive index than that of the low refractive index layer (ie, a high refractive index layer and a medium refractive index layer) on a transparent substrate. It is provided and formed.

  Colloidal metal by multilayer deposition of transparent thin films of inorganic compounds (metal oxides, etc.) with different refractive indexes by chemical vapor deposition (CVD) method, physical vapor deposition (PVD) method, sol-gel method of metal compounds such as metal alkoxides Examples include a method of forming a thin film by post-processing (ultraviolet irradiation: JP-A-9-157855, plasma processing: JP-A-2002-327310) after forming an oxide particle film.

  On the other hand, various antireflection films formed by laminating thin films in which inorganic particles are dispersed in a matrix have been proposed as antireflection films with high productivity.

  The antireflection film which consists of the antireflection layer which provided the anti-glare property which the antireflection film by application | coating as mentioned above provided the surface of the uppermost layer with the shape of a fine unevenness | corrugation is mentioned.

  The optical resin film of the present invention can be applied to any of the above methods, but a coating method (coating type) is particularly preferable.

(C-1) Layer structure of coating type antireflection film An antireflection film comprising a layer structure of at least a medium refractive index layer, a high refractive index layer, and a low refractive index layer (outermost layer) on the substrate has the following relationship: It is designed to have a refractive index that satisfies

The refractive index of the high refractive index layer> The refractive index of the medium refractive index layer> The refractive index of the transparent support> The refractive index of the low refractive index layer Further, a hard coat layer is provided between the transparent support and the medium refractive index layer. May be. Furthermore, it may consist of a medium refractive index hard coat layer, a high refractive index layer and a low refractive index layer.

  Examples thereof include JP-A-8-122504, JP-A-8-110401, JP-A-10-300902, JP-A-2002-243906, JP-A-2000-11706, and the like.

  Other functions may be imparted to each layer, for example, an antifouling low refractive index layer or an antistatic high refractive index layer (eg, JP-A-10-206603, JP-A-2002). -243906 publication etc.) etc. are mentioned.

  The haze of the antireflection film is preferably 5% or less, more preferably 3% or less. Further, the strength of the film is preferably H or more, more preferably 2H or more, and most preferably 3H or more in a pencil hardness test according to JIS K5400.

(C-2) High Refractive Index Layer and Medium Refractive Index Layer The antireflective layer having a high refractive index is a curable film containing at least inorganic compound ultrafine particles having a high refractive index with an average particle size of 100 nm or less and a matrix binder. Consists of.

  Examples of the high refractive index inorganic compound fine particles include inorganic compounds having a refractive index of 1.65 or more, preferably those having a refractive index of 1.9 or more. Examples thereof include oxides such as Ti, Zn, Sb, Sn, Zr, Ce, Ta, La, and In, and composite oxides containing these metal atoms.

  In order to obtain such ultrafine particles, the surface of the particles is treated with a surface treatment agent (for example, silane coupling agents, etc .: JP-A-11-295503, JP-A-11-153703, JP-A-2000-9908). No., anionic compound or organometallic coupling agent: Japanese Patent Laid-Open No. 2001-310432, etc., core-shell structure with high refractive index particles as a core (: Japanese Patent Laid-Open No. 2001-166104, etc.), specific dispersion (For example, Japanese Patent Laid-Open No. 11-153703, Japanese Patent No. US6210858B1, Japanese Patent Laid-Open No. 2002-27776069, etc.).

  Examples of the material forming the matrix include conventionally known thermoplastic resins and curable resin films.

  Further, it is selected from a polyfunctional compound-containing composition containing at least two radically polymerizable and / or cationically polymerizable groups, an organometallic compound containing a hydrolyzable group, and a partial condensate composition thereof. At least one composition is preferred. Examples thereof include compounds described in JP-A Nos. 2000-47004, 2001-315242, 2001-31871, and 2001-296401.

  A curable film obtained from a colloidal metal oxide obtained from a hydrolyzed condensate of metal alkoxide and a metal alkoxide composition is also preferred. For example, it describes in Unexamined-Japanese-Patent No. 2001-293818.

  The refractive index of the high refractive index layer is generally 1.70 to 2.20. The thickness of the high refractive index layer is preferably 5 nm to 10 μm, and more preferably 10 nm to 1 μm.

  The refractive index of the middle refractive index layer is adjusted to be a value between the refractive index of the low refractive index layer and the refractive index of the high refractive index layer. The refractive index of the middle refractive index layer is preferably 1.50 to 1.70.

(C-3) Low refractive index layer The low refractive index layer is formed by sequentially laminating on the high refractive index layer. The refractive index of the low refractive index layer is 1.20 to 1.55. Preferably it is 1.30-1.50.

  It is preferable to construct as the outermost layer having scratch resistance and antifouling property. As means for greatly improving the scratch resistance, imparting slipperiness to the surface is effective, and conventionally known thin film layer means such as introduction of silicone or introduction of fluorine can be applied.

  The refractive index of the fluorine-containing compound is preferably 1.35 to 1.50. More preferably, it is 1.36-1.47. The fluorine-containing compound is preferably a compound containing a crosslinkable or polymerizable functional group containing fluorine atoms in the range of 35 to 80% by mass.

  For example, paragraph numbers [0018] to [0026] of Japanese Patent Application Laid-Open No. 9-222503, paragraph numbers [0019] to [0030] of Japanese Patent Application Laid-Open No. 11-38202, and paragraph numbers of Japanese Patent Application Laid-Open No. 2001-40284. [0027] to [0028], JP-A 2000-284102, and the like.

  The silicone compound is a compound having a polysiloxane structure, preferably containing a curable functional group or a polymerizable functional group in the polymer chain and having a crosslinked structure in the film. For example, reactive silicone (eg, Silaplane (manufactured by Chisso Corporation), silanol group-containing polysiloxane (Japanese Patent Laid-Open No. 11-258403, etc.) and the like can be mentioned.

  The crosslinking or polymerization reaction of the fluorine-containing and / or siloxane polymer having a crosslinking or polymerizable group is carried out at the same time or after the coating composition for forming the outermost layer containing a polymerization initiator, a sensitizer, etc. It is preferable to carry out by light irradiation or heating.

  Also preferred is a sol-gel cured film in which an organometallic compound such as a silane coupling agent and a specific fluorine-containing hydrocarbon group-containing silane coupling agent are cured by a condensation reaction in the presence of a catalyst.

  For example, a polyfluoroalkyl group-containing silane compound or a partially hydrolyzed condensate thereof (Japanese Patent Laid-Open Nos. 58-142958, 58-147483, 58-147484, Japanese Patent Laid-Open Nos. 9-157582, 11) -106704), silyl compounds containing a poly "perfluoroalkyl ether" group which is a fluorine-containing long chain group (Japanese Patent Application Laid-Open Nos. 2000-117902, 2001-48590, 2002) 53804), and the like.

  The low refractive index layer has an average primary particle diameter of 1 to 150 nm such as a filler (for example, silicon dioxide (silica), fluorine-containing particles (magnesium fluoride, calcium fluoride, barium fluoride)) as an additive other than the above. Low refractive index inorganic compounds, organic fine particles described in paragraphs [0020] to [0038] of JP-A-11-3820, etc.), silane coupling agents, slip agents, surfactants, and the like can be contained.

  When the low refractive index layer is located below the outermost layer, the low refractive index layer may be formed by a vapor phase method (vacuum deposition method, sputtering method, ion plating method, plasma CVD method, etc.). The coating method is preferable because it can be manufactured at a low cost.

  The film thickness of the low refractive index layer is preferably 30 to 200 nm, more preferably 50 to 150 nm, and most preferably 60 to 120 nm.

(C-4) Hard coat layer The hard coat layer is provided on the surface of the transparent support in order to impart physical strength to the antireflection film. In particular, it is preferably provided between the transparent support and the high refractive index layer.

  The hard coat layer is preferably formed by a crosslinking reaction or a polymerization reaction of a light and / or heat curable compound.

  The curable functional group is preferably a photopolymerizable functional group, and the hydrolyzable functional group-containing organometallic compound is preferably an organic alkoxysilyl compound.

  Specific examples of these compounds are the same as those exemplified for the high refractive index layer.

  Specific examples of the composition of the hard coat layer include those described in JP-A Nos. 2002-144913, 2000-9908, and WO 00/46617.

  The high refractive index layer can also serve as a hard coat layer. In such a case, it is preferable to form fine particles dispersed in the hard coat layer using the method described for the high refractive index layer.

  The hard coat layer can also serve as an antiglare layer (described later) provided with particles having an average particle size of 0.2 to 10 μm to provide an antiglare function (antiglare function).

  The film thickness of the hard coat layer can be appropriately designed depending on the application. The film thickness of the hard coat layer is preferably 0.2 to 10 μm, more preferably 0.5 to 7 μm.

  The strength of the hard coat layer is preferably H or higher, more preferably 2H or higher, and most preferably 3H or higher in a pencil hardness test according to JIS K5400. Further, in the Taber test according to JIS K5400, the smaller the wear amount of the test piece before and after the test, the better.

(C-5) Forward scattering layer The forward scattering layer is provided in order to give a viewing angle improvement effect when the viewing angle is inclined in the vertical and horizontal directions when applied to a liquid crystal display device. By dispersing fine particles having different refractive indexes in the hard coat layer, it can also serve as a hard coat function.

  For example, Japanese Patent Laid-Open No. 11-38208 specifying a forward scattering coefficient, Japanese Patent Laid-Open No. 2000-199809 having a relative refractive index of a transparent resin and fine particles in a specific range, and Japanese Patent Laid-Open No. 2002 specifying a haze value of 40% or more. -107512 gazette etc. are mentioned.

(C-6) Other layers In addition to the above layers, a primer layer, an antistatic layer, an undercoat layer, a protective layer, and the like may be provided.

(C-7) Coating method Each layer of the antireflection film is formed by a dip coating method, an air knife coating method, a curtain coating method, a roller coating method, a wire bar coating method, a gravure coating, a micro gravure method or an extrusion coating method (US patent). No. 2,681,294) can be formed by coating.

(C-8) Anti-glare function The antireflection film may have an anti-glare function that scatters external light. The antiglare function is obtained by forming irregularities on the surface of the antireflection film. When the antireflection film has an antiglare function, the haze of the antireflection film is preferably 3 to 30%, more preferably 5 to 20%, and most preferably 7 to 20%.

  As a method for forming irregularities on the surface of the antireflection film, any method can be applied as long as these surface shapes can be sufficiently maintained. For example, a method of forming irregularities on the film surface using fine particles in the low refractive index layer (for example, JP 2000-271878 A), a lower layer of the low refractive index layer (high refractive index layer, medium refractive index layer) Alternatively, a small amount (0.1 to 50% by mass) of relatively large particles (particle size 0.05 to 2 μm) is added to the hard coat layer to form a surface uneven film, and these shapes are maintained thereon. A method of providing a low refractive index layer (for example, JP 2000-281410 A, JP 2000-95893 A, JP 2001-100004 A, 2001-281407, etc.), an uppermost layer (antifouling layer) A method of physically transferring the uneven shape onto the surface after coating (for example, as an embossing method, Japanese Patent Laid-Open Nos. 63-278839, 11-183710, 2000-275401) It includes equal forth) and the like.

<Measurement method>
The measurement method used in the present invention is described below.

(1) Range of Rth / Re ratio and Rth / Re ratio [1] After slitting 5 cm at both ends of the film, 20 points were sampled at regular intervals over the entire width (3 cm × 3 cm square). At this time, each side of the square was cut out parallel to MD (film forming direction) and TD (width direction).

  [2] After adjusting the sample film to 25 ° C. and 60% relative humidity for 5 hours or more, using an automatic birefringence meter (KOBRA-21ADH: manufactured by Oji Scientific Instruments) at 25 ° C. and 60% relative humidity As described above, the retardation value at a wavelength of 550 nm was measured from the direction inclining by 10 ° from the normal direction to the sample film surface and ± 50 ° from the normal to the film surface.

  [3] In-plane retardation (Re) from the vertical (normal) direction, and retardation (Rth) in the thickness direction were calculated from the measured values in the vertical direction and ± 10 to 40 ° directions.

  [4] The average value of the Rth / Re ratio at each of these measurement points was defined as “Re / Rth ratio”. The difference between the maximum value and the minimum value among the 20 Rth / Re ratios was defined as the “Rth / Re ratio range”.

(2) Thermal dimensional change, thermal dimensional change unevenness [1] Sampling is performed at a point obtained by dividing the entire width of the following sample into five equal parts.
B) MD sample: MD15cm x TD5cm
B) TD sample: TD15cm × MD5cm
[2] Each sample is conditioned at 25 ° C. and 60% rh for 3 hours or more, and measured in this environment using a 10 cm-basic pin gauge. This is L1.

  [3] Each sample is allowed to stand at 80 ° C. and dry for 200 hours, then conditioned for 3 hours or more at 25 ° C. and 60% rh, and measured in this environment using a 10 cm base length pin gauge. This is L2.

  [4] The thermal dimensional change at each point (10 points) of MD and TD is measured from the following formula, and this average value is defined as the thermal dimensional change.

Thermal dimensional change (%) = 100 × | L2-L1 | / L1
[5] The difference between the maximum value and the minimum value of the thermal dimensional change (absolute value) among the 10 points was divided by the average value of the 10 thermal dimensional changes, and the thermal dimensional change was uneven.

(3) Ra was measured using a surface roughness compact laser interferometer (F601 manufactured by Fuji Photo Optical Co., Ltd.).

(4) Glass transition temperature (Tg)
20 mg of the sample was placed in a measurement pan of a scanning differential calorimeter (DSC). This was heated from 30 ° C. to 250 ° C. at 10 ° C./min in a nitrogen stream (1st-run), and then cooled to 30 ° C. at −10 ° C./min. Thereafter, the temperature was raised again from 30 ° C. to 250 ° C. (2nd-run). The glass transition temperature (Tg) was defined as the temperature at which the baseline began to deviate from the low temperature side at 2nd-run.

  The features of the present invention will be described more specifically with reference to examples and comparative examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

[Example]
The film was manufactured using TOPAS # 6013 (Tg = 140 ° C.) as a resin and Irganox 1010 (0.1 wt%) as an additive. The screw extruder used was a full flight single screw. The screw outlet pressure was controlled by the number of rotations of a gear pump provided downstream.

  Moreover, about the Example which performed nitrogen flow from the inlet_port | entrance of a screw extruder, it carried out at flow volume 10L / min so that atmospheric oxygen concentration might be 1% or less. Moreover, about the Example using a filter, the metal fiber filter with a nominal diameter of 10 micrometers was used.

  The test conditions and results are shown in FIG. In addition, about the result, the film formed by melt extrusion was melt | dissolved in cyclohexane at normal temperature, and was 10 wt%. This solution was measured with a haze meter (NDH2000 manufactured by Nippon Densyoku). A larger haze means more gel, and the haze value is preferably 10% or less, more preferably 3% or less, and even more preferably 1% or less.

  In Examples 1 to 5 in which the outlet pressure of the extruder is in the range of 0.1 to 7.0 MPa, the solution haze is 10% or less, the generation of gel is small, and a high quality film can be produced. It was. In Examples 2 and 3 which are the upper limit and the lower limit of the outlet pressure, the solution haze was 10% or less. On the contrary, in Comparative Examples 1 and 2 in which the outlet pressure exceeded 7.0 MPa, the solution haze exceeded 10%. Further, in Comparative Example 3 in which the outlet pressure was 0.0 MPa, the discharge amount was not stable, and a film could not be produced.

In Examples 6 to 9 carried out by changing the residence time, the solution haze was high in Example 9 in which the residence time was shorter than 1 minute, but it was 10% or less. Furthermore, Examples 10 to 12 in which the groove depth ratio H ₁ / H ₂ was larger than 1.5 and smaller than 2.5, Examples 14 to 16 in which the pellet filling ratio was 70 to 100%, and the input resin temperature was Examples 17 to 19 which were lower than 140 ° C. (Tg) and higher than 60 ° C. (Tg-80), Examples 20 and 21 in which the oxygen concentration at the inlet of the extruder was 0 to 10%, and Example 22 where a filter was provided Thus, it was confirmed that by adding each component, the haze value was lowered and the generation of gel was reduced.

It is a model diagram which shows the structure of the film manufacturing apparatus used for the manufacturing method of the resin film of this invention. It is a model diagram which shows a structure in a screw extruder. It is a table | surface figure which shows the test conditions of an Example, and a result.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Film manufacturing apparatus, 12 ... Resin film, 14 ... Film forming process part, 16 ... Longitudinal stretch process part, 18 ... Lateral stretch process part, 20 ... Winding process part, 22 ... Extruder, 24 ... Die, 26 ... Cooling drum, 32 ... cylinder, 34 ... screw shaft, 36 ... screw flight part, 38 ... screw, 40 ... supply port, 42 ... discharge port

Claims (8)

In a method for producing an optical resin film using a melt film-forming method in which a cyclic olefin resin is heated and melted with a screw extruder and discharged from a molding die into a film shape,
The screw extruder is a single screw extruder;
The method for producing an optical resin film, wherein an outlet pressure of the screw extruder is 0.1 MPa to 7.0 MPa.   The method for producing an optical resin film according to claim 1, wherein an average residence time from the screw extruder to the forming die is 1 minute or more and 30 minutes or less. Groove depth H of the screw extruder of the screw flight portion is, the ratio of groove depth H ₂ of at groove depth H ₁ and the resin outlet portion of a resin inlet of the screw extruder, is H 1 _/ H ₂ The method for producing an optical resin film according to claim 1, wherein the method is greater than 1.5 and less than 2.5.   The method for producing an optical resin film according to any one of claims 1 to 3, wherein a resin filling rate in a melt state or a pellet state inside the screw extruder is 70 to 100%. A heating step of heating the cyclic olefin-based resin before charging the screw extruder;
When the glass transition point of the cyclic olefin resin is Tg,
The temperature T ₀ ° C of the cyclic olefin-based resin immediately before feeding into the screw extruder is higher than (Tg-80) ° C and lower than Tg ° C, and the temperature fluctuation range is ± 5 ° C or less. The manufacturing method of the optical resin film in any one of Claim 1 to 4.   The method for producing an optical resin film according to any one of claims 1 to 5, wherein an oxygen concentration at an inlet of the screw extruder is 0 to 10%.   The method for producing an optical resin film according to any one of claims 1 to 6, wherein a filter is installed at an outlet of the screw extruder.   An optical film having a haze of 10% or less when the film obtained by the method for producing an optical resin film according to claim 1 is used as a 10% cyclohexane solution.

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