JP2008307831A - Cyclic polyolefine type resin film and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a film with a high optical characteristics by suppressing a generation of a residual strain caused by a polishing roller method and preventing a fluctuation in thickness or a liner scratch from generating. <P>SOLUTION: The manufacturing method of a cyclic polyolefine type resin film 12 comprises melting the cyclic polyolefine type resin and extruding the molten resin to a sheet form through a die 24 and cooling and solidifying the molten resin by holding the sheet by a couple of roll 26 and 28 whose surface flatness of an arithmetical mean height Ra is not more than 100 nm and at least one of the rolls is composed of an elastic roll 26 made of a metal wherein a lip clearance d of the die 24 is set in a range of 0.2 to 1.0 mm and further a resin flow rate of the resin per a unit area in die extrusion opening 24C is set in a range of 0.1 to 1.5 kg/mm<SP>2</SP>. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a cyclic polyolefin resin film and a method for producing the same, and more particularly to a cyclic polyolefin resin film having a quality suitable for a liquid crystal display device and a method for producing the same.

  Conventionally, a cyclic polyolefin resin film can be stretched to develop in-plane retardation (Re) and retardation in the thickness direction (Rth), and used as a retardation film of a liquid crystal display device to increase the viewing angle. It has been implemented.

  As a method of stretching such a cyclic polyolefin-based resin film, a method of stretching in the machine (longitudinal) direction of the film (longitudinal stretching), a method of stretching in the transverse (width) direction of the film (transverse stretching), or longitudinal stretching And a method of simultaneously performing transverse stretching (simultaneous stretching). Of these, longitudinal stretching has been used in the past because of its compact equipment. Normally, longitudinal stretching is performed in the longitudinal direction by heating the film between two or more pairs of nip rolls to a glass transition temperature (Tg) or higher and increasing the transport speed on the outlet side to the transport speed of the nip roll on the inlet side. Is the method.

Patent Document 1 describes a method of longitudinally stretching a thermoplastic resin such as a cyclic polyolefin resin. This patent document 1 improves the unevenness of the angle of the slow axis by reversing the longitudinal stretching direction from the casting film forming direction. Patent Document 2 describes a method in which a nip roller installed between short spans having an aspect ratio (L / W) of 0.3 or more and 2 or less is installed in a stretching zone for stretching. According to Patent Document 2, the thickness direction orientation (Rth) can be improved. The aspect ratio here refers to a value obtained by dividing the interval (L) of the nip rolls used for stretching by the width (W) of the thermoplastic resin film to be stretched.
JP 2002-311240 A JP 2003-315551 A

  By the way, when the cyclic polyolefin resin film before stretching (unstretched) is formed by the melt film forming method, the cyclic polyolefin resin has a problem that it is difficult to level because the melt viscosity is high. For this reason, the cyclic polyolefin resin film formed by the melt film forming method has a problem that streak failure is likely to occur and a problem that the thickness accuracy is lowered.

  The inventor of the present invention paid attention to the polishing roller method as a method for solving these problems. This polishing roller method is a method in which the resin extruded from the die is cooled while being sandwiched between a pair of polishing rollers, and the thickness accuracy can be improved.

  However, the polishing roller method has a problem that residual distortion tends to occur in the film. In addition, even if the film is formed by the polishing roller method, depending on the conditions for extruding the molten polyolefin resin from the die, the film thickness variation and surface quality deteriorate, so there is a problem that a high-performance optical film cannot be obtained. there were.

  The present invention has been made in view of such circumstances, and a cyclic polyolefin capable of obtaining a film having high optical characteristics by suppressing the occurrence of residual distortion by the polishing roller method and optimizing the die conditions. An object of the present invention is to provide a resin film and a method for producing the same.

In order to achieve the above object, the invention according to claim 1 melts the cyclic polyolefin-based resin and extrudes it into a sheet form from a die, and the sheet has at least a surface property with an arithmetic average height Ra of 100 nm or less. A method for producing a cyclic polyolefin-based resin film in which one roll is cooled and solidified by being sandwiched between a pair of rollers constituted by a metal elastic roll, the lip clearance of the die being 0.2 to While being set to a range of 1.0 mm, the resin flow rate per unit area at the die extrusion port is set to a range of 0.1 to 1.5 kg / mm ² per hour.

According to the invention described in claim 1, since the molten cyclic polyolefin-based resin extruded from the die is sandwiched between a pair of rollers in which at least one roll is constituted by a metallic elastic roll, and is cooled and solidified. The cyclic polyolefin resin is pressed by a pair of rollers. Thus, when the resin is cooled while being pressed in a planar shape, a film having no residual stress is formed. However, when the sheet is pressed into a sheet shape, the thickness becomes uniform. On the other hand, if the molten resin extruded into a sheet has surface quality defects such as subtle thickness fluctuations and streak failure due to a die, the retardation Re, Rth It turned out that the distribution of becomes remarkable. Therefore, the inventors set the die lip clearance in the range of 0.2 to 1.0 mm and the resin flow rate at the die lip in the range of 0.1 to 1.5 kg / mm ² per hour. As a result, it was found that the thickness variation and surface quality of the film can be prevented from deteriorating. Here, the lip clearance of the die is set in the range of 0.2 to 1.0 mm because when the lip clearance becomes smaller than 0.2 mm, the pressure of the molten resin changes rapidly at the die lip. If thickness fluctuation or streak failure occurs and the thickness exceeds 1.0 mm, the draw ratio becomes too large and the thickness accuracy deteriorates, and the resin flow rate at the die lip is 0.1 to 0.1 per hour. The reason why the range of 1.5 kg / mm ² is set is that when the flow rate is smaller than 0.1 kg / mm ² , the production amount is remarkably inferior, and when the flow rate is larger than 1.5 kg / mm ² , This is because, when the pressure of the molten resin becomes too large, thickness fluctuations and streak failures occur in the film.

  Therefore, according to the invention of claim 1, a film having no residual stress is formed by cooling and solidifying the cyclic polyolefin resin between a pair of rollers in which at least one roll is constituted by a metal elastic roll. In addition, by controlling the die lip clearance and flow rate, it is possible to prevent the occurrence of thickness fluctuations and streak failures in the film. Therefore, a method for producing a cyclic polyolefin resin film having no retardation Re, Rth distribution is provided. Can be provided.

  The invention according to claim 2 is characterized in that, in the invention according to claim 1, the R chamfering or C chamfering of the edge portion of the die is 30 μm or less.

  This is because when the chamfering of the edge portion of the die exceeds 30 μm, it causes a streak failure. Therefore, according to the invention of claim 2, since the R chamfering or C chamfering of the edge portion of the die is 30 μm or less, no streak failure occurs. A method for producing a cyclic polyolefin resin film having no distribution of Re and Rth can be provided.

  The invention described in claim 3 is characterized in that, in the invention of claim 1 or 2, the center line average roughness Ra of the die lip surface of the die is 0.5 μm or less.

  When the molten resin is discharged from the die into the atmosphere with a discharge pressure, the molten resin swells slightly, so that it easily comes into contact with the lip surface. When the surface roughness of the lip surface is large, the molten resin tends to adhere when it comes into contact, causing a streak failure. If the center line average roughness Ra of the lip surface exceeds 0.5 μm, a streak failure will occur. Is significantly increased. Therefore, according to the invention of claim 3, when the center line average roughness Ra of the die lip surface of the die is 0.5 μm or less, no streak failure occurs as in the invention of claim 2. Therefore, it is possible to provide a method for producing a cyclic polyolefin resin film having no distribution of retardation Re and Rth even when pressed in a planar shape.

  The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein the die lip surface of the die has a Vickers hardness of 500 or more.

  This is because if the hardness of the lip surface of the die is less than 500 in terms of Vickers hardness, the lip surface is likely to be scratched, and streak failure due to this scratch is likely to occur. Therefore, according to the fourth aspect, since the hardness of the die lip surface is 500 or more in terms of Vickers hardness, no streak failure occurs as in the second and third aspects of the invention. It is possible to provide a method for producing a cyclic polyolefin resin film having no distribution of retardation Re and Rth even when pressed in a shape.

  The invention according to claim 5 is characterized in that, in the invention according to any one of claims 1 to 4, the zero-shear viscosity of the cyclic polyolefin-based resin when discharged from the die is 2000 Pa · sec or less. To do.

  According to the invention of claim 5, the distribution of retardation Re and Rth is remarkable even when pressed in a planar form because the zero shear viscosity of the cyclic polyolefin resin when discharged from the die is 2000 Pa · sec or less. Can be prevented. If the zero shear viscosity exceeds 2000 Pa · sec, the molten resin discharged from the die spreads immediately after discharge and tends to adhere to the tip of the die, which becomes dirty and easily causes streak failure. . The zero shear viscosity is measured by measuring the shear rate dependency data of the melt viscosity with a plate cone type melt viscosity measuring device, and the melt viscosity at the zero shear rate is determined from the measured value in the region where the melt viscosity does not depend on the shear rate. Is obtained by extrapolating.

  The invention according to claim 6 is the invention according to any one of claims 1 to 5, wherein the film thickness is 20 to 300 μm, the in-plane retardation Re is 20 nm or less, and the retardation Rth in the thickness direction is 20 nm or less. It is characterized by being.

  According to the present invention, a cyclic polyolefin resin film suitable for an optical film having a high thickness accuracy and a small distribution of retardation Re and Rth can be produced, so that the thickness is 20 to 300 μm and the in-plane retardation ( A cyclic polyolefin resin film having a Re) of 20 nm or less and a thickness direction retardation (Rth) of 20 nm or less can be obtained.

  A seventh aspect of the present invention is a cyclic polyolefin-based resin film manufactured by the manufacturing method according to any one of the first to sixth aspects, and an eighth aspect is a substrate based on the cyclic polyolefin-based resin film of the seventh aspect. An optical compensation film for a liquid crystal display panel, characterized in that it is used in the present invention. Claim 9 is a polarizing plate characterized in that at least one cyclic polyolefin-based resin film of claim 7 is laminated.

  Since the cyclic polyolefin-type resin film manufactured with the manufacturing method of Claims 1-6 has a high optical characteristic, it is suitable for the optical compensation film for liquid crystal display plates, or a polarizing plate.

  According to the present invention, the molten cyclic polyolefin-based resin extruded from the die is cooled and solidified by sandwiching at least one roll between two rollers each made of a metal elastic roll. When sandwiched between, the cyclic polyolefin resin is pressed into a planar shape by a metal roller, and a film without residual stress can be formed, and the die lip clearance and flow rate are controlled to extrude into a sheet shape. It is possible to prevent occurrence of surface variations such as thickness fluctuation and streak failure in the molten resin, and a cyclic polyolefin resin film having no distribution of retardation Re and Rth even when pressed in a planar shape and its A manufacturing method can be provided.

  Hereinafter, preferred embodiments of a method for producing a cyclic polyolefin 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 an apparatus for producing a cyclic polyolefin resin film. As shown in FIG. 1, the production apparatus 10 mainly longitudinally stretches the cyclic polyolefin resin film 12 produced in the film production process unit 14 that produces the cyclic polyolefin resin film 12 before stretching and the film production process unit 14. It is comprised by the longitudinal stretch process part 16, the transverse stretch process part 18 laterally stretched, and the winding process part 20 which winds up the cyclic | annular polyolefin-type resin film 12 extended | stretched.

  In the film forming process section 14, the cyclic polyolefin resin melted by the extruder 22 is discharged from the die 24 into a sheet shape and supplied between a pair of rotating polishing rollers 26 and 28. Then, after the cyclic polyolefin resin film 12 cooled and solidified on the polishing roller 28 is peeled off from the polishing roller 28, it is sent to the longitudinal stretching process section 16 and the lateral stretching process section 18 in order and stretched, and the winding process. It is wound up in a roll shape at the section 20. Thereby, the stretched cyclic polyolefin resin film 12 is manufactured. Hereinafter, details of each process part will be described.

  FIG. 2 shows a single screw extruder 22 of the film forming process section 14. As shown in FIG. 2, a single shaft screw 38 having a flight 36 on a screw shaft 34 is disposed in the cylinder 32, and cyclic polyolefin resin is supplied into the cylinder 32 from a hopper (not shown) through a supply port 40. The In the cylinder 32, in order from the supply port 40 side, a supply unit (region indicated by A) for quantitatively transporting the cyclic polyolefin resin supplied from the supply port 40, and a compression unit (at B) for kneading and compressing the cyclic polyolefin resin. And a measuring portion (region indicated by C) for measuring the kneaded and compressed cyclic polyolefin-based resin. The cyclic polyolefin resin melted by the extruder 22 is continuously sent from the discharge port 42 to the die 24.

  The screw compression ratio of the extruder 22 is set to 2.5 to 4.5, and L / D is set to 20 to 70. Here, the screw compression ratio is represented by the volume ratio between the supply unit A and the metering unit C, that is, the volume per unit length of the supply unit A ÷ the volume per unit length of the metering unit C. Is calculated using the outer diameter d1 of the screw shaft 34, the outer diameter d2 of the screw shaft 34 of the measuring section C, the groove diameter a1 of the supply section A, and the groove diameter a2 of the measuring section C. L / D is the ratio of the cylinder length (L) to the cylinder inner diameter (D) in FIG. Moreover, extrusion temperature is set to 200-300 degreeC. When the temperature in the extruder 22 exceeds 300 ° C., a cooler (not shown) may be provided between the extruder 22 and the die 24.

  The extruder 22 may be a single-screw extruder or a twin-screw extruder. However, if the screw compression ratio is less than 2.5 and is too small, the extruder 22 is not sufficiently kneaded, and an undissolved part is generated, or a shear heating is generated. The crystal is small and the melting of the crystal becomes insufficient, and fine crystals are likely to remain in the cyclic polyolefin-based resin film after manufacture, and bubbles are more likely to be mixed. As a result, when the cyclic polyolefin resin film 12 is stretched, the remaining crystals hinder stretchability and the orientation cannot be sufficiently increased. On the other hand, if the screw compression ratio exceeds 4.5 and is too large, the shear stress is excessively applied and the resin is easily deteriorated due to heat generation, so that the cyclic polyolefin-based resin film after production is easily yellowed. On the other hand, if the shear stress is excessively applied, the molecules are cut and the molecular weight is lowered, so that the mechanical strength of the film is lowered. Accordingly, the screw compression ratio is preferably in the range of 2.5 to 4.5, more preferably 2.8 to 4 in order to make the cyclic polyolefin-based resin film after production hardly yellow and stretch and break. .2 range, particularly preferably in the range of 3.0 to 4.0.

  On the other hand, if L / D is less than 20 and is too small, melting or kneading is insufficient, and fine crystals are likely to remain in the produced cyclic polyolefin-based resin film as in the case where the compression ratio is small. On the other hand, if L / D exceeds 70 and is too large, the residence time of the cyclic polyolefin resin in the extruder 22 becomes too long, and the resin tends to deteriorate. In addition, when the residence time is long, the molecules are cut, the molecular weight is lowered, and the mechanical strength of the film is lowered. Therefore, L / D is preferably in the range of 20 to 70, preferably in the range of 22 to 65, particularly preferably 24, in order to make the cyclic polyolefin-based resin film after production hardly yellow and hardly break. It is in the range of ~ 50.

  Also, if the extrusion temperature is too low below 200 ° C., the crystals are not sufficiently melted, and fine crystals are likely to remain in the produced cyclic polyolefin resin film, and when the cyclic polyolefin resin film is stretched. The stretchability is hindered and the orientation cannot be sufficiently increased. On the other hand, when the extrusion temperature exceeds 300 ° C. and is too high, the cyclic polyolefin-based resin is deteriorated and the degree of yellowness (YI value) is deteriorated. Therefore, in order to make the cyclic polyolefin-based resin film after production hardly yellow and hardly stretch and break, the extrusion temperature is preferably 200 to 300 ° C, preferably 220 to 290 ° C, particularly preferably 240 to 240 ° C. The range is 280 ° C.

  The cyclic polyolefin resin is melted using the extruder 22 configured as described above, and this molten resin is continuously supplied to the die 24 shown in FIG. 3- (A) or FIG. 3- (B).

The molten resin continuously supplied from the extruder 22 to the die 24 is spread in the width direction by a manifold (not shown) in the die 24, and is passed through a narrow slit 24A to obtain a die lip 24C (a slit outlet at the die tip). It is discharged from. Lip lands 24B and 24B are formed on the surface of the die lip 24C with the slit 24A interposed therebetween. The lip clearance d, which is the clearance width of the slit 24A, is set in the range of 0.2 to 1.0 mm, and the resin flow rate in the die lip 24C is set in the range of 0.1 to 1.5 kg / mm ² per hour. Set.

This is because when the slit 24A is very narrow such that the lip clearance d of the die 24 is less than 0.2 mm, molten resin adheres to the outlet of the die lip 24C, and surface defects such as streak failures are likely to occur due to the adhered matter. Because it becomes. Further, if the lip clearance d of the die 24 exceeds 1000 mm, the draw ratio becomes too high, and the thickness accuracy of the produced cyclic polyolefin resin film 12 is deteriorated. When the resin flow rate of the die lip 24C is smaller than 0.1 kg / mm ² per hour, the productivity is remarkably deteriorated, and the resin flow rate of the die lip 24C is 1.5 kg / mm ² per hour. If it is larger than the range, the pressure of the molten resin at the die lip 24C is too large, resulting in thickness fluctuations and streak failures in the film.

  Furthermore, it is preferable that the R chamfering of the edge portion 24D of the die 24 shown in FIG. 3- (A) or the C chamfering of the edge portion 24D of the die 24 shown in FIG. 3- (B) is 30 μm or less.

  The center line average roughness (Ra) of the surface of the die lip 24C, that is, the lip lands 24B and 24B is preferably 0.5 μm or less.

  This is because when the molten resin is discharged from the die 24 into the atmosphere with a discharge pressure, the molten resin slightly swells and thus easily comes into contact with the lip lands 24B and 24B. Therefore, if the surface roughness of the lip lands 12a and 12b is large, the molten resin is liable to adhere when contacted, causing a streak failure. Specifically, when the center line average roughness (Ra) of the lip lands 12a and 12b exceeds 0.5 μm, the occurrence of streak failures increases. Further, even if the chamfering of the edge portion 24D of the die lip 24C is either the R chamfering or the C chamfering, if it exceeds 30 μm, it causes a streak failure.

  The hardness of the lip lands 24B and 24B is also related to the surface quality of the produced cyclic polyolefin resin film 12, and the lip lands 24B and 24B preferably have a Vickers hardness of 500 or more. This is because if the Vickers hardness is less than 500, the lip lands 24B and 24B are likely to be damaged, and a streak failure due to the damage is likely to occur.

  Molten resin is discharged in a sheet form from the tip (lower end) of the die 24 thus formed. It is preferable that the zero-shear viscosity of the cyclic polyolefin-based resin when discharged is 2000 Pa · sec or less. If the zero shear viscosity exceeds 2000 Pa · sec, the molten resin discharged from the die spreads immediately after discharge and tends to adhere to the tip of the die, which becomes dirty and easily causes streak failure. . The discharged molten resin is supplied between a pair of polishing rollers 26 and 28 (see FIG. 1).

  FIG. 3 shows an embodiment of a pair of polishing rollers 26 and 28. In the pair of polishing rollers 26 and 28, one roll is constituted by a metal elastic roll 26 and the other roll is constituted by a cooling roll 28.

  Each of the polishing rollers 26 and 28 has a mirror surface or a state close to the mirror surface, and the arithmetic average height Ra is set to 100 nm or less, preferably 50 nm or less, more preferably 25 nm or less. Further, the polishing rollers 26 and 28 are configured to be able to control the surface temperature. For example, the surface temperature can be controlled by circulating a liquid medium such as water inside the polishing rollers 26 and 28. ing. Further, the pair of polishing rollers 26 and 28 are connected to a rotation driving means such as a motor, and are rotated at a speed substantially equal to the speed at which the molten resin discharged from the die 24 lands. .

  Of the pair of polishing rollers 26, 28, the polishing roller 26 is formed with a smaller diameter than the other polishing roller 28, the surface is made of a metal material, and the surface temperature can be controlled with high accuracy. Yes. The polishing roller 26 includes an outer cylinder 44, a liquid medium layer 46, an elastic body layer (inner cylinder) 48, and a metal shaft 50 in this order from the outer layer. The outer cylinder 44 and the inner cylinder 48 of the elastic roll 26 are rotated by the rotation of the cooling roll 28 that contacts through the sheet-like molten resin. When the sheet-like molten resin is sandwiched between the pair of rollers 26, 28, the elastic roll 26 receives a reaction force from the cooling roll 28 via the sheet-like molten resin, and elastically deforms into a concave shape following the surface of the cooling roll 28. To do. Accordingly, the elastic roll 26 and the cooling roll 28 are in surface contact with the sheet, and the cooling roll 28 is pressed while the sandwiched sheet is pressed into a planar shape by a restoring force that restores the elastic deformed elastic roll 26 to its original shape. Cooled by. The outer cylinder 44 is made of a metal thin film and preferably has a seamless structure without a welded joint. The wall thickness Z of the outer cylinder 44 is preferably in the range of 0.05 mm <Z <7.0 mm. If the thickness Z is 0.05 mm or less, the outer cylinder cannot withstand the pressure and the surface does not appear, and if it is 7.0 mm or more, elasticity is not obtained and the effect of eliminating the distortion does not appear. The outer cylinder wall thickness Z is satisfactory if it satisfies 0.05 mm <Z <7.0 mm, but more preferably 0.2 mm <Z <5.0 mm.

Further, when the glass transition temperature Tg (° C.) of the cyclic polyolefin resin—the temperature (° C.) of the elastic roll 26 is X (° C.), and the line speed is Y (m / min), 0.0043 X ² +0.12 X + 1. It is preferable to set the line speed Y and the temperature of the polishing roller (elastic roll) 26 so as to satisfy 1 <Y <0.019X ² + 0.73X + 24. When the line speed Y is 0.0043X ² + 0.12X + 1.1 or less, the pressing time is too long and the film is distorted. When the line speed Y is 0.019X ² + 0.73X + 24 or more, the cooling time is This is because the film is too short to remove the film and sticks to the elastic roll.

Further, the length of contact between the elastic roll 26 and the cooling roll 28 of the pair of polishing rollers 26 and 28 is Q (cm), and the linear pressure between the elastic roll 26 and the cooling roll 28 is P (kg / cm). It is preferable to set the linear pressure P and the contact length Q so as to satisfy 3 kg / cm ² <P / Q <50 kg / cm ² . This is because when the P / Q is 3 kg / cm ² or less, the sheet cannot be contacted in a planar manner, and when the P / Q is 50 kg / cm ² or more, distortion of the film appears.

  According to the film forming process section 14 configured as described above, by discharging the cyclic polyolefin-based resin from the die 24, the discharged cyclic polyolefin-based resin is very little liquid between the pair of polishing rollers 26 and 28. A pool (bank) is formed, and this cyclic polyolefin resin is sandwiched between a pair of polishing rollers 26 and 28 to form a sheet while the thickness is adjusted. At that time, the polishing roller 26 which is a metal elastic roll is elastically deformed by the reaction force of the cyclic polyolefin resin, and the cyclic polyolefin resin is pressed into a planar shape by the polishing roller 26. Therefore, by pressing in a planar shape, a film having no residual stress can be formed, and by controlling the lip clearance and flow rate of the die 24, the thickness of the molten resin extruded into a sheet shape can be changed. Since it is possible to prevent the occurrence of surface defects due to streak failure, a cyclic polyolefin resin film 12 suitable for an optical film having no distribution of retardation Re and Rth even when pressed in a planar shape is produced. Can do.

  Further, according to the film forming process section 14 configured as described above, the cyclic polyolefin resin film having a film thickness of 20 to 300 μm, an in-plane retardation Re of 20 nm or less, and a thickness direction retardation Rth of 20 nm or less. 12 can be manufactured.

  Here, the retardations Re and Rth are obtained by the following equations.

Re (nm) = | n (MD) −n (TD) | × T (nm)
Rth (nm) = | {(n (MD) + n (TD)) / 2} −n (TH) | × T (nm)
In the formula, n (MD), n (TD), and n (TH) represent the refractive index in the longitudinal direction, the width direction, and the thickness direction, and T represents the thickness in nm.

  The film 12 sandwiched between the pair of polishing rollers 26 and 28 is wound around a metal polishing roller 28 and cooled, and then peeled off from the surface of the polishing roller 28, and the longitudinal stretching process section 16 in the subsequent stage. Sent to.

  Below, the extending | stretching process until extending | stretching the cyclic polyolefin-type resin film 12 manufactured by the film forming process part 14 and manufacturing the extended cyclic polyolefin-type resin film 12 is demonstrated.

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

  As shown in FIG. 1, the cyclic polyolefin resin film 12 is first longitudinally stretched in the longitudinal direction by a longitudinal stretching step 16. In the longitudinal stretching process section 16, after the cyclic polyolefin resin film 12 is preheated, the cyclic polyolefin resin film 12 is wound around two nip rolls 30 and 31 in a heated state. The nip roll 31 on the outlet side conveys the cyclic polyolefin resin film 12 at a higher conveyance speed than the nip roll 30 on the inlet side, whereby the cyclic polyolefin 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. 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 longitudinally stretched cyclic polyolefin-based resin film 12 is sent to the transverse stretching step section 18 and is transversely stretched in the width direction. For example, a tenter can be suitably used in the lateral stretching step 18, and both ends of the cyclic polyolefin-based resin film 12 in the width direction are held with clips by the tenter and stretched 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, and 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, Rth is 0 nm to 500 nm, more preferably 50 nm to 400 nm, Preferably they are 70 nm or more and 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.

  As described above, according to the present embodiment, it is possible to produce the cyclic polyolefin-based resin film 12 that has no streak failure in the film-forming process unit 14, has high thickness accuracy, and has low distortion. Since the resin film 12 is stretched in the longitudinal direction and the transverse direction, the cyclic polyolefin resin film 12 having no stretching distribution can be produced.

The stretched cyclic polyolefin-based 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 cyclic polyolefin resin film 12 is preferably 0.02 kg / mm ² or less. By setting the winding tension in such a range, the stretched cyclic polyolefin resin film 12 can be wound without causing a retardation distribution.

<Cyclic polyolefin resin>
In the present invention, as the cyclic polyolefin resin (cycloolefin resin) in the present invention, any of cycloolefin resin-A and cycloolefin resin-B described later can be preferably used.

(Cycloolefin resin-A / ring-opening polymerization type)
Examples of the cycloolefin resin (cycloolefin resin-A) used in the present invention include (1) a ring-opening (co) polymer of a norbornene monomer, such as maleic acid addition and cyclopentadiene addition as required. After polymer modification, hydrogenated resin, (2) resin obtained by addition polymerization of norbornene monomer, and (3) addition copolymerization with norbornene monomer and olefin monomer such as ethylene or α-olefin. Resins etc. can be mentioned. The polymerization method and the hydrogenation method can be performed by conventional methods.

  Examples of the norbornene-based monomer include norbornene and alkyl and / or alkylidene substituted products thereof such as 5-methyl-2-norbornene, 5-dimethyl-2-norbornene, 5-ethyl-2-norbornene, and 5-butyl. 2-Norbornene, 5-ethylidene-2-norbornene, and the like, polar substituents such as halogens thereof; dicyclopentadiene, 2,3-dihydrodicyclopentadiene, etc .; dimethanooctahydronaphthalene, its alkyl and / or alkylidene Substituents and polar group substituents such as halogen such as 6-methyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6- Ethyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-oct Hydronaphthalene, 6-ethylidene-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-chloro-1,4: 5,8-dimethano -1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-cyano-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a -Octahydronaphthalene, 6-pyridyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-methoxycarbonyl-1,4: 5 8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, etc .; adducts of cyclopentadiene and tetrahydroindene, etc .; 3-pentamers of cyclopentadiene, such as 4,9 : 5,8-dimethano-3a, 4,4a, , 8,8a, 9,9a-octahydro-1H-benzoindene, 4,11: 5,10: 6,9-trimethano-3a, 4,4a, 5,5a, 6,9,9a, 10,10a, 11,11a-dodecahydro-1H-cyclopentanthracene; and the like.

(Cycloolefin resin-B / ring-opening polymerization type)
Moreover, what is represented by the following general formula (1)-(4) can be mentioned as cycloolefin type resin, Among these, what is represented by the following general formula (1) is especially preferable.

[In the general formulas (1) to (4), A, B, C and D represent a hydrogen atom or a monovalent organic group, and at least one of them is a polar group. ]
The weight average molecular weight of these cycloolefin resins is usually preferably 5,000 to 1,000,000, more preferably 8,000 to 200,000.

  Examples of the cycloolefin resin in the present invention include, for example, JP-A-60-168708, JP-A-62-252406, JP-A-62-2252407, JP-A-2-133413, JP-A-63. Examples thereof include resins described in JP-A-145324, JP-A-63-264626, JP-A-1-240517, and JP-B-57-8815.

  Among these resins, those obtained by addition polymerization of norbornene monomers are particularly preferable.

  The glass transition temperature (Tg) of these cycloolefin resins is preferably 80 ° C. or higher and 230 ° C. or lower, more preferably 100 ° C. or higher and 200 ° C. or lower, and further preferably 120 ° C. or higher and 180 ° C. or lower. The saturated water absorption is preferably 1% by mass or less, and more preferably 0.8% by mass or less. The glass transition temperature (Tg) and saturated water absorption of the cycloolefin resins represented by the general formulas (1) to (4) can be controlled by selecting the type of the substituents A, B, C, and D. .

  As the cycloolefin resin in the present invention, at least one tetracyclododecene derivative represented by the following general formula (5) is used alone, or the tetracyclododecene derivative can be copolymerized with the tetracyclododecene derivative. A hydrogenated polymer obtained by hydrogenating a polymer obtained by metathesis polymerization with a cyclic compound may be used.

(In the formula, A, B, C and D represent a hydrogen atom or a monovalent organic group, and at least one of them is a polar group.)
In the tetracyclododecene derivative represented by the general formula (5), when at least one of A, B, C and D is a polar group, the polarized light has excellent adhesion to other materials, heat resistance, etc. A film can be obtained. Further, the polar group is a group represented by — (CH ₂ ) _n COOR (where R is a hydrocarbon group having 1 to 20 carbon atoms, and n is an integer of 0 to 10). The resulting hydrogenated polymer (polarizing film substrate) is preferred because it has a high glass transition temperature. In particular, the polar substituent represented by — (CH ₂ ) _n COOR is preferably contained in one molecule of the tetracyclododecene derivative of the general formula (5) from the viewpoint of reducing the water absorption rate. In the polar substituent, it is preferable in that the hygroscopicity of the obtained hydrogenated polymer decreases as the number of carbon atoms of the hydrocarbon group represented by R increases, but the balance with the glass transition temperature of the obtained hydrogenated polymer is reduced. From this point, the hydrocarbon group is preferably a chain alkyl group having 1 to 4 carbon atoms or a (poly) cyclic alkyl group having 5 or more carbon atoms, and particularly preferably a methyl group, an ethyl group, or a cyclohexyl group. preferable.

Furthermore, the tetracyclododecene derivative of the general formula (5) in which a hydrocarbon group having 1 to 10 carbon atoms is bonded as a substituent to a carbon atom to which a group represented by — (CH ₂ ) _n COOR is bonded, This is preferable because the resulting hydrogenated polymer has low hygroscopicity. In particular, the tetracyclododecene derivative of the general formula (5) in which the substituent is a methyl group or an ethyl group is preferable in terms of easy synthesis. Specifically, 8-methyl-8-methoxycarbonyltetracyclo [4,4,0,12.5,17.10] dodec-3-ene is preferable. These tetracyclododecene derivatives and mixtures of unsaturated cyclic compounds copolymerizable therewith are described, for example, in JP-A-4-77520, page 4, upper right column, line 12 to page 6, lower right column, line 6. Metathesis polymerization and hydrogenation can be carried out by the prepared method.

These cycloolefin resins preferably have an intrinsic viscosity (ηinh) measured at 30 ° C. in chloroform of 0.1 to 1.5 dl / g, more preferably 0.4 to 1.2 dl / g. g. Moreover, as a hydrogenation rate of a hydrogenated polymer, the value measured by 60 MHz and < ¹ > H-NMR shall be 50% or more, Preferably it is 90% or more, More preferably, it is 98% or more. The higher the hydrogenation rate, the more the resulting cycloolefin film is more stable against heat and light. The gel content contained in the hydrogenated polymer is preferably 5% by mass or less, and more preferably 1% by mass or less.

  Furthermore, a cycloolefin resin (addition polymerization type) having the following structure can be used for the film of the present invention. In the present invention, as the cycloolefin resin, [A-1]: a hydrogenated random copolymer of an α-olefin having 2 to 20 carbon atoms and a cyclic olefin represented by the following formula (I), [ A-2]: a ring-opened polymer or copolymer hydrogenated product of a cyclic olefin represented by the following formula (I).

  These cycloolefin resins preferably have a glass transition temperature (Tg) measured by DSC of 70 ° C. or higher, more preferably 70 to 250 ° C., and particularly preferably 120 to 180 ° C.

  Further, these cycloolefin resins are amorphous or low crystalline, and the crystallinity measured by X-ray diffraction method is usually 20% or less, preferably 10% or less, more preferably 2%. It is as follows.

  The cycloolefin of the present invention has an intrinsic viscosity [η] measured in decalin at 135 ° C. of usually 0.01 to 20 dl / g, preferably 0.03 to 10 dl / g, more preferably 0. The melt flow index (MFR) measured at a load of 2.16 kg at 260 ° C. according to ASTM D1238 is usually 0.1 to 200 g / 10 minutes, preferably 1 to 100 g / 10 minutes. More preferably, it is 5 to 50 g / 10 minutes.

  Furthermore, the softening point of cycloolefin resin is normally 30 degreeC or more as a softening point measured with the thermal mechanical analyzer (TMA), Preferably it is 70 degreeC or more, More preferably, it is 80-260 degreeC.

   Details of the structure of the cycloolefin resin represented by the above formula (I) will be described.

In the above formula (I), n is 0 or 1, m is 0 or an integer of 1 or more, and q is 0 or 1. In addition, when q is 1, R ^a and R ^b are each independently the atoms or hydrocarbon groups shown below. When q is 0, each bond is bonded to form a 5-membered member. Form a ring.

R ^{1 to} R ¹⁸ and R ^a and R ^b are each independently a hydrogen atom, a halogen atom or a hydrocarbon group. Here, the halogen atom is a fluorine atom, a chlorine atom, a bromine atom or an iodine atom.

Moreover, as a hydrocarbon group, a C1-C20 alkyl group, a C3-C15 cycloalkyl group, and an aromatic hydrocarbon group are mentioned normally each independently. More specifically, examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, an amyl group, a hexyl group, an octyl group, a decyl group, a dodecyl group, and an octadecyl group, and the cycloalkyl group includes a cyclohexyl group. Group, and examples of the aromatic hydrocarbon group include a phenyl group and a naphthyl group. These hydrocarbon groups may be substituted with a halogen atom. Further, in the above formula (I), R ^{15 to} R ¹⁸ may be bonded to each other (in cooperation with each other) to form a monocyclic or polycyclic ring, and the monocyclic or polycyclic ring thus formed The polycycle may have a double bond.

  Specific examples of the cyclic olefin represented by the above formula (I) are shown below. As an example,

  Bicyclo [2.2.1] -2-heptene (= norbornene) represented by the formula (in the above general formula, the numbers 1 to 7 represent carbon position numbers) and a derivative in which a hydrocarbon group is substituted on the compound Can be mentioned.

  As this substituted hydrocarbon group, 5-methyl, 5,6-dimethyl, 1-methyl, 5-ethyl, 5-n-butyl, 5-isobutyl, 7-methyl, 5-phenyl, 5-methyl-5-phenyl , 5-benzyl, 5-tolyl, 5- (ethylphenyl), 5- (isopropylphenyl), 5- (biphenyl), 5- (β-naphthyl), 5- (α-naphthyl), 5- (anthracenyl) , 5,6-diphenyl and the like.

  Still other derivatives include cyclopentadiene-acenaphthylene adduct, 1,4-methano-1,4,4a, 9a-tetrahydrofluorene, 1,4-methano-1,4,4a, 5,10,10a-hexahydro Bicyclo [2.2.1] -2-heptene derivatives such as anthracene can be exemplified.

In addition, tricyclo [4.3.0.1 ^2,5 ] -3-decene, 2-methyltricyclo [4.3.0.1 ^2,5 ] -3-decene, 5-methyltricyclo [4.3.0.1 ^2,5 ] -3 Tricyclo [4.3.0.1 ^2,5 ] -3-decene derivatives such as -decene, tricyclo [4.4.0.1 ^2,5 ] -3-undecene, 10-methyltricyclo [4.4.0.1 ^2,5 ] -3-undecene Tricyclo [4.4.0.1 ^2,5 ] -3-undecene derivatives, such as

In tetracyclo shown [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene, and this hydrocarbon group include derivatives substituted.

  As its hydrocarbon group, 8-methyl, 8-ethyl, 8-propyl, 8-butyl, 8-isobutyl, 8-hexyl, 8-cyclohexyl, 8-stearyl, 5,10-dimethyl, 2,10-dimethyl, 8,9-dimethyl, 8-ethyl-9-methyl, 11,12-dimethyl, 2,7,9-trimethyl, 2,7-dimethyl-9-ethyl, 9-isobutyl-2,7-dimethyl, 9, 11,12-trimethyl, 9-ethyl-11,12-dimethyl, 9-isobutyl-11,12-dimethyl, 5,8,9,10-tetramethyl, 8-ethylidene, 8-ethylidene-9-methyl, 8 -Ethylidene-9-ethyl, 8-ethylidene-9-isopropyl, 8-ethylidene-9-butyl, 8-n-propylidene, 8-n-propylidene-9-methyl, 8-n-propylidene-9-ethyl, 8 -n-propylidene-9-isopropyl, 8-n-propylidene-9-butyl, 8-isopropylidene, 8-isopropylidene-9-methyl, 8-isopropylidene-9-ethyl, 8-isopropylidene-9-isopropyl 8-Isopropylidene-9-butyl, 8-chloro, 8-bromo, 8-fluoro, 8,9-dichloro, 8-phenyl, 8-methyl-8-phenyl, 8-benzyl, 8-tolyl, 8- ( Ethylphenyl), 8- (isopropylphenyl), 8,9-diphenyl, 8- (biphenyl), 8- (β-naphthyl), 8- (α-naphthyl), 8- (anthracenyl), 5,6-diphenyl Etc. can be illustrated.

Furthermore, - tetracyclo such (cyclopentadiene acenaphthylene adduct) and adduct of cyclopentadiene [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene derivatives, pentacyclo [6.5.1.1 ^{3, 6} .0 ^2,7 .0 ^9,13] -4-pentadecene and its derivatives, pentacyclo ^{[7.4.0.1 2,5 .1 9,12 .0 8,13]} -3- pentadecene and its derivatives, pentacyclo [8.4.0.1 ^{2 , 5.1 9,12} .0 ^8,13] -3-hexadecene and derivatives thereof, pentacyclo ^{[6.6.1.1 3,6 .0 2,7 .0 9,14]} -4- hexadecene and derivatives thereof, hexacyclo [ ^{6.6.1.1 3,6 .1 10,13 .0 2,7 .0 9,14} ] -4- heptadecene and its derivatives, heptacyclo [8.7.0.1 ^2,9 .1 ^4,7 .1 ^11,17 .0 ^3,8 .0 ^12,16] -5-eicosene and its derivatives, heptacyclo ^{[8.7.0.1 3,6 .1 10,17 .1 12,15 .0} 2,7 .0 11,16] -4- eicosene and its derivatives, heptacyclo ^{[8.8.0.1 2,9 .1 4,7 .1 11,18 .0} 3,8 .0 12,17] -5- heneicosene Oyo Beauty derivatives thereof, octacyclo ^{[8.8.0.1 2,9 .1 4,7 .1 11,18 .1} 13,16 .0 3,8 .0 12, 17] -5- docosenoic and derivatives thereof, Nonashikuro [10.9.1.1 ^4,7 .1 ^13,20 .1 ^15,18 .0 ^{2 10} .0 ^3,8 .0 ^12,21 .0 ^14,19] -5-pentacosene and derivatives thereof.

  Specific examples of these cycloolefin resins are as described above, but more specific structures of these compounds are shown in paragraphs [0032] to [0054] of JP-A-7-145213. Has been.

  Moreover, about the synthesis method of these cycloolefin resin, it can carry out with reference to paragraph number [0039]-[0068] of Unexamined-Japanese-Patent No. 2001-114836 specification.

  The following can also be used as the cycloolefin resin (addition polymerization type) of the present invention.

  Formula I, II, II ', III, IV, V or VI

Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are the same or different and are hydrogen, eg linear or branched C ₁ -C ₈ - alkyl group, C ₆ -C ₁₈ - aryl groups, C ₇ -C ₂₀ - alkylene aryl group, cyclic or acyclic C ₂ ~C ₂₀ - C _1, such as alkenyl groups -C ₂₀ - hydrocarbon radical And forms a saturated, unsaturated or aromatic ring, and the same groups R ^{1 to} R ⁸ may be different in different formulas I to VI, and n is 0 to 5). 0 to 99 mol% of the following formula VII based on the polymerized unit of at least one cyclic olefin and the total structure of the cycloolefin copolymer:

Wherein R ⁹ , R ¹⁰ , R ¹¹ and R ¹² are the same or different and are linear, such as hydrogen, for example a C ₁ -C ₈ -alkyl group or a C ₆ -C ₁₈ -aryl group, At least selected from the group consisting of polymers comprising polymerized units derived from one or more acyclic olefins represented by a branched, saturated or unsaturated C ₁ -C ₂₀ -hydrocarbon group) One type of cycloolefin copolymer may be used.

  Cycloolefin polymers can also be obtained by ring-opening polymerization of at least one of the monomers having the formulas I to VI and then hydrogenating the resulting product.

  Furthermore, 0 to 45 mol% of the following formula VIII based on the total structure of the cycloolefin copolymer:

  (Wherein n is a number of 2 to 10), and can include a polymer unit derived from one or more types of monocyclic olefins.

  The proportion of polymerized units derived from cyclic, in particular polycyclic olefins, is preferably 3 to 75 mol%, based on the total structure of the cycloolefin copolymer. The proportion of polymerized units derived from the acyclic olefin is preferably 5 to 80 mol% based on the total structure of the cycloolefin copolymer.

The cycloolefin copolymer is preferably a polymerized unit derived from one or more polycyclic olefins, in particular a polycyclic olefin represented by formula I or formula III, and one or more types represented by formula VII. It consists of polymerized units derived from acyclic olefins, in particular α-olefins having 2 to 20 carbon atoms. Preference is given in particular to cycloolefin copolymers consisting of polymerized units derived from polycyclic olefins of the formula I or formula III and polymerized units derived from acyclic olefins of the formula VII. Preferably, further, polymerized units derived from polycyclic monoolefins of formula I or formula III, polymerized units derived from acyclic monoolefins of formula VII, and at least two duplexes Cyclic or acyclic olefins (polyenes) containing bonds, especially cyclic, preferably polycyclic dienes such as norbornadiene, particularly preferably such as vinyl norbornene carrying a C ₂ -C ₂₀ -alkenyl group A terpolymer comprising polymerized units derived from a polycyclic alkene.

  The cycloolefin polymer according to the invention preferably comprises an olefin based on a norbornene structure, particularly preferably norbornene, tetracyclododecene, if desired vinyl norbornene or norbornadiene. Also preferably a cycloolefin copolymer comprising polymerized units derived from α-olefins having for example 2 to 20 carbon atoms, particularly preferably acyclic olefins having terminal double bonds such as ethylene or propylene. is there. Particularly preferred are norbornene / ethylene copolymers and tetracyclododecene / ethylene copolymers.

  Among the terpolymers, norbornene / vinylnorbornene / ethylene terpolymer, norbornene / norbornadiene / ethylene terpolymer, tetracyclododecene / vinylnorbornene / ethylene terpolymer, and tetracyclododecene / vinyltetracyclododecene are particularly preferable. -Ethylene terpolymer. The proportion of polymerized units derived from polyenes, preferably vinyl norbornene or norbornadiene, is 0.1 to 50 mol%, particularly preferably 0.1 to 20 mol%, based on the total structure of the cycloolefin copolymer, The proportion of the acyclic monoolefin represented by VII is 0 to 99 mol%, preferably 5 to 80 mol%. In the terpolymer, it is 0.1 to 99 mol%, preferably 3 to 75 mol%, based on the entire structure of the cycloolefin copolymer.

  Preferably, the cycloolefin copolymer according to the present invention comprises polymerized units that can be derived from a polycyclic olefin of formula I and polymer units that can be derived from an acyclic olefin of formula VII. Including at least one cycloolefin copolymer.

  Such a cycloolefin copolymer can be synthesized according to paragraph numbers [0019] to [0020] of JP-A-10-168201.

(Additive)
(1) Antioxidant The cycloolefin resin in the present invention includes known antioxidants such as 2,6-di-t-butyl-4-methylphenol, 2,2′-dioxy-3,3′-. Di-t-butyl-5,5′-dimethylphenylmethane, tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane, 1,1,3-tris (2 -Methyl-4-hydroxy-5-t-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, stearyl -Β- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 2,2'-dioxy-3,3'-di-t-butyl-5,5'-diethylphenylmethane, 3, 9-bis [1,1- Methyl-2- [β- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy] ethyl], 2,4,8,10-tetraoxpiro [5,5] undecane, tris (2 , 4-Di-t-butylphenyl) phosphite, cyclic neopentanetetraylbis (2,4-di-t-butylphenyl) phosphite, cyclic neopentanetetraylbis (2,6-di-t) -Butyl-4-methylphenyl) phosphite, 2,2-methylenebis (4,6-di-t-butylphenyl) octyl phosphite; UV absorbers such as 2,4-dihydroxybenzophenone, 2-hydroxy-4- It can be stabilized by adding methoxybenzophenone or the like. Further, additives such as a lubricant can be added for the purpose of improving processability.

  The addition amount of these antioxidants is 0.1-3 mass parts normally with respect to 100 mass parts of cycloolefin resin, Preferably it is 0.2-2 mass parts.

Furthermore, you may add various additives, such as anti-aging agents, such as a phenol type and phosphorus type | system | group, an antistatic agent, a ultraviolet absorber, and an easy-lubricant, to a cycloolefin type resin as desired.
(2) Stabilizer In the present invention, it is preferable to use either or both of a phosphite compound and a phosphite compound as a stabilizer. The blending amount of these stabilizers is preferably 0.005 to 0.5% by mass with respect to the cycloolefin resin, more preferably 0.01 to 0.4% by mass, and still more preferably 0.8. It is 02-0.3 mass%.
(I) Phosphite stabilizer Although the specific phosphite stabilizer is not specifically limited, The phosphite stabilizer shown by Formula (2)-(4) is preferable.

In the above formulas, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ′ ¹ , R ′ ² , R ′ ³ ... R ′ ^p and R ′ ^{p + 1} are hydrogen or carbon. A group consisting of an alkyl group, an aryl group, an alkoxyalkyl group, an aryloxyalkyl group, an alkoxyaryl group, an arylalkyl group, an alkylaryl group, a polyaryloxyalkyl group, a polyalkoxyalkyl group, and a polyalkoxyaryl group of formula 4-23 Represents a group selected from However, not all of the same formulas in the general formulas (2), (3), and (4) become hydrogen. X in the phosphite stabilizer represented by the general formula (3) is an aliphatic chain, an aliphatic chain having an aromatic nucleus in a side chain, an aliphatic chain having an aromatic nucleus in the chain, and two in the chain. A group selected from the group consisting of chains containing non-continuous oxygen atoms. K and q are integers of 1 or more, and p is an integer of 3 or more. )
The values of k and q of these phosphite stabilizers are preferably 1 to 10. Setting the values of k and q to 1 or more reduces the volatility during heating, and setting it to 10 or less is preferable because compatibility with cellulose acetate propionate is improved. Moreover, the value of p is preferably 3 to 10. By setting p to a value of 3 or more, volatility during heating is reduced, and setting it to 10 or less is preferable because compatibility with cellulose acetate propionate is improved.

  As specific examples of the phosphite stabilizer represented by the following general formula (2), those represented by the following formulas (5) to (8) are preferable.

  Moreover, as a specific example of the phosphite stabilizer represented by the following general formula (3), those represented by the following formulas (9), (10), and (11) are preferable.

(Ii) Phosphite ester stabilizer The phosphite ester stabilizer is, for example, cyclic neopentanetetraylbis (octadecyl) phosphite, cyclic neopentanetetraylbis (2,4-di-tert- Butylphenyl) phosphite, cyclic neopentanetetraylbis (2,6-di-tert-butyl-4-methylphenyl) phosphite, 2,2-methylenebis (4,6-di-tert-butylphenyl) octyl Examples thereof include phosphite and tris (2,4-di-tert-butylphenyl) phosphite.

(Iii) Other stabilizers In addition, weak organic acids, thioether compounds, epoxy compounds and the like may be added as stabilizers.

  The weak organic acid is not particularly limited as long as it has a pKa of 1 or more, does not interfere with the action of the present invention, and has coloration prevention properties and physical property deterioration prevention properties. Examples thereof include tartaric acid, citric acid, malic acid, fumaric acid, oxalic acid, succinic acid, maleic acid and the like. These may be used alone or in combination of two or more.

  Examples of the thioether compound include dilauryl thiodipropionate, ditridecyl thiodipropionate, dimyristyl thiodipropionate, distearyl thiodipropionate, and palmityl stearyl thiodipropionate. It may be used in combination, or two or more may be used in combination.

  Examples of the epoxy compound include those derived from epichlorohydrin and bisphenol A, such as derivatives from epichlorohydrin and glycerin, vinylcyclohexene dioxide, and 3,4-epoxy-6-methylcyclohexylmethyl-3,4-epoxy-6. -Cyclic ones such as methylcyclohexanecarboxylate can also be used. Epoxidized soybean oil, epoxidized castor oil, long chain α-olefin oxides, and the like can also be used. These may be used alone or in combination of two or more.

(3) Matting agent It is preferable to add fine particles as a matting agent. The fine particles used in the present invention include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate and Mention may be made of calcium phosphate.

  These fine particles usually form secondary particles having an average particle size of 0.1 to 3.0 μm, and these fine particles exist in the film as aggregates of primary particles, and 0.1 to 0.1 μm on the film surface. An unevenness of 3.0 μm is formed. The secondary average particle size is preferably 0.2 μm to 1.5 μm, more preferably 0.4 μm to 1.2 μm, and most preferably 0.6 μm to 1.1 μm. For the primary and secondary particle sizes, the particles in the film were observed with a scanning electron microscope, and the diameter of a circle circumscribing the particles was defined as the particle size. In addition, 200 particles were observed at different locations, and the average value was taken as the average particle size.

  A preferable addition amount of the fine particles is preferably 1 ppm to 5000 ppm, more preferably 5 ppm to 1000 ppm, and still more preferably 10 ppm to 500 ppm by mass ratio with respect to the cycloolefin resin.

  Fine particles containing silicon are preferable because turbidity can be lowered, and silicon dioxide is particularly preferable. The fine particles of silicon dioxide preferably have a primary average particle size of 20 nm or less and an apparent specific gravity of 70 g / liter or more. Those having an average primary particle size as small as 5 to 16 nm are more preferred because they can reduce the haze of the film. The apparent specific gravity is preferably 90 to 200 g / liter or more, and more preferably 100 to 200 g / liter or more. A larger apparent specific gravity is preferable because a high-concentration dispersion can be produced, and haze and aggregates are improved.

  As the fine particles of silicon dioxide, for example, commercially available products such as Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (above, manufactured by Nippon Aerosil Co., Ltd.) can be used. Zirconium oxide fine particles are commercially available, for example, under the trade names Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.), and can be used.

  Among these, Aerosil 200V and Aerosil R972V are fine particles of silicon dioxide having a primary average particle size of 20 nm or less and an apparent specific gravity of 70 g / liter or more. This is particularly preferable because the effect of lowering the coefficient is great.

(4) Other additives As other additives, infrared absorbing dyes, optical adjusting agents, and surfactants can be added. These details are disclosed in the Invention Association Public Technique No. 2001-1745 (issued March 15, 2001, Invention Association), p. Materials described in detail in 17-22 are preferably used.

  As the infrared absorbing dye, for example, those disclosed in JP-A No. 2001-194522 can be used, and as the ultraviolet absorber, for example, those described in JP-A No. 2001-151901 can be used. It is preferable to contain 001-5 mass%.

  Examples of the optical adjusting agent include a retardation adjusting agent. For example, those described in JP 2001-166144 A, JP 2003-344655 A, JP 2003-248117 A, and JP 2003-66230 A. Can be used. Thereby, in-plane retardation (Re) and thickness direction retardation (Rth) can be controlled. A preferable addition amount is 0 to 10% by mass with respect to cellulose acylate, more preferably 0 to 8% by mass, and still more preferably 0 to 6% by mass.

  As the ultraviolet absorber, a benzophenone-based ultraviolet absorber, a benzotriazole-based ultraviolet absorber, an acrylonitrile-based ultraviolet absorber, or the like can be used. Among them, a benzophenone-based ultraviolet absorber is preferable, and the addition amount is usually 10 ˜100,000 ppm, preferably 100 to 10,000 ppm.

《Filming》
(1) Pelletization The thermoplastic resin and the additive are preferably mixed and pelletized prior to melt film formation.

  It is preferable to dry the thermoplastic resin and the additive in advance for pelletization, but drying can be substituted by using a vent type extruder. When drying, as the drying method, a method of heating in a heating furnace at 90 ° C. for 8 hours or more can be used, but not limited thereto. Pelletization can be performed by melting the thermoplastic resin and additives at 150 ° C. to 280 ° C. using a twin-screw kneading extruder and then extruding them into noodles and solidifying and cutting in water. 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.

  Any known single-screw extruder, non-meshing counter-rotating twin-screw extruder, meshing-type counter-rotating twin-screw extruder, meshing co-direction as long as the melter kneading is sufficient A rotary twin screw extruder or the like can be used.

The preferred size is the cross-sectional area of 1 mm ² to 300 mm ² of the pellets, is 1mm~30mm is Preferably length, more preferably the cross-sectional area of 2 mm ² 100 mm ^2, the length is 1.5Mm～10mm.

  Moreover, when pelletizing, the said additive can also be injected | thrown-in from the raw material input port and vent port in the middle of an extruder.

  The number of revolutions of the extruder is preferably 10 rpm to 1000 rpm, more preferably 20 rpm to 700 rpm, and even more preferably 30 rpm to 500 rpm. Accordingly, when the rotational speed is slow, the residence time becomes long, which is not preferable because the molecular weight is lowered due to thermal deterioration or the yellowishness is easily deteriorated. On the other hand, if the rotational speed is too high, molecules are likely to be cut by shearing, which leads to problems such as a decrease in molecular weight and an increase in the generation of cross-linked gel.

  The extrusion residence time in pelletization is 10 seconds or more and within 30 minutes, more preferably 15 seconds to 10 minutes, and further preferably 30 seconds to 3 minutes. If sufficient melting is possible, a shorter residence time is preferable in terms of suppressing resin deterioration and yellowing.

(2) Drying It is preferable to reduce moisture in the pellets prior to melt film formation. The drying method is often dried using a dehumidifying air dryer, but is not particularly limited as long as the desired moisture content can be obtained (heating, blowing, decompression, stirring, etc. alone or in combination) It is preferable to use it efficiently, and more preferably, the drying hopper is preferably a heat insulating structure). The drying temperature is preferably 0 to 200 ° C, more preferably 40 to 180 ° C, and particularly preferably 60 to 150 ° C. When the drying temperature is too low, not only does drying take time, but the moisture content does not fall below the target value, which is not preferable. On the other hand, if the drying temperature is too high, the resin sticks and is not preferable. The amount of drying air used is preferably 20 to 400 m ³ / time, more preferably 50 to 300 m ³ / hour, and particularly preferably 100 to 250 m ³ / hour. If the amount of drying air is small, the drying efficiency is unfavorable. On the other hand, even if the air volume is increased, if the amount is more than a certain amount, further improvement of the drying effect is small and not economical. The dew point of air is preferably 0 to -60 ° C, more preferably -10 to -50 ° C, and particularly preferably -20 to -40 ° C. The drying time is required to be at least 15 minutes, more preferably 1 hour or more, and particularly preferably 2 hours or more. On the other hand, even if the drying time exceeds 50 hours, the effect of further reducing the moisture content is small, and there is a concern about thermal degradation of the resin, so it is not preferable to unnecessarily increase the drying time. The thermoplastic resin of the present invention preferably has a moisture content of 1.0% by mass or less, more preferably 0.1% by mass or less, and particularly preferably 0.01% by mass or less.

(3) Melt extrusion The above-mentioned cycloolefin resin is supplied into the cylinder through the supply port of the extruder. The cylinder was melt kneaded and compressed in order from the supply port side, a supply part (region A) for quantitatively transporting the thermoplastic resin supplied from the supply port, and a compression unit (region B) for melt kneading and compressing the thermoplastic resin. It is comprised with the measurement part (area | region C) which measures a thermoplastic resin. The resin is preferably dried in order to reduce the water content by the above-mentioned method. However, in order to prevent oxidation of the molten resin by residual oxygen, the inside of the extruder is in an inert (nitrogen or the like) air flow or with a vent. More preferably, it is carried out while evacuating using an extruder. The screw compression ratio of the extruder is set to 2.5 to 4.5, and L / D is set to 20 to 70. Here, the screw compression ratio is expressed by the volume ratio between the supply unit A and the metering unit C, that is, the volume per unit length of the supply unit A ÷ the volume per unit length of the metering unit C. It is calculated using the outer diameter d1 of the shaft, the outer diameter d2 of the screw shaft of the measuring part C, the groove part diameter a1 of the supply part A, and the groove part diameter a2 of the measuring part C. L / D is the ratio of the cylinder length to the cylinder inner diameter. Moreover, extrusion temperature is set to 200-300 degreeC. The temperatures in the extruder may all be the same temperature or may have a temperature distribution. More preferably, the temperature of the supply section is made higher than the temperature of the compression section.

  If the screw compression ratio is less than 2.5 and is too small, it will not be sufficiently melt-kneaded and undissolved parts will occur, undissolved foreign matter will easily remain in the manufactured thermoplastic film, and bubbles will be mixed. It becomes easy. As a result, the strength of the thermoplastic film is lowered, or when the film is stretched, it becomes easy to break and the orientation cannot be sufficiently increased. On the other hand, if the screw compression ratio exceeds 4.5, the shear stress is excessively applied and the resin is easily deteriorated by heat generation, so that a yellowish color is likely to appear in the manufactured thermoplastic film. On the other hand, when too much shear stress is applied, the molecules are cut and the molecular weight is lowered, so that the mechanical strength of the film is lowered. Therefore, the screw compression ratio is preferably in the range of 2.5 to 4.5, more preferably 2. In order to make the thermoplastic film after production hardly yellow, and the film strength is strong and the film is not easily stretched and broken. It is 8 to 4.2, particularly preferably in the range of 3.0 to 4.0.

  On the other hand, if L / D is less than 20 and is too small, melting and kneading are insufficient, and undissolved foreign matter is likely to be generated in the manufactured thermoplastic film as in the case where the compression ratio is small. On the other hand, if L / D exceeds 70 and is too large, the residence time of the thermoplastic resin in the extruder becomes too long, and the resin tends to be deteriorated. Further, when the residence time is long, the molecules are cut or the molecular weight is lowered, so that the mechanical strength of the thermoplastic film is lowered. Therefore, L / D is preferably in the range of 20 to 70, more preferably in the range of 22 to 65, in order to make the thermoplastic film after production hardly yellowish and the film strength is strong and further difficult to stretch and break. Especially preferably, it is the range of 24-50.

  The cycloolefin film thus obtained has characteristic values having a haze of 2.0% or less and a yellow index (YI value) of 10 or less.

  Generally, single-screw extruders with relatively low equipment costs are often used as the types of extruders, and there are screw types such as full flight, madok, and dalmage. Is preferred. In addition, although the equipment cost is expensive, it is possible to use a twin-screw extruder that can extrude while volatilizing unnecessary volatile components by providing a vent port in the middle by changing the screw segment. There are two types of shaft extruders, the same direction and the different direction, which can be used. However, the type of the same direction rotation with high self-cleaning performance is preferred because a stagnant portion is hardly generated. By properly arranging the vent port, it is possible to use the cycloolefin pellets and powder in an undried state as they are. In addition, film smears produced during film formation can be reused without drying.

  In addition, although the diameter of a preferable screw changes with target extrusion rates per unit time, it is 10 mm-300 mm, More preferably, it is 20 mm-250 mm, More preferably, it is 30 mm-150 mm.

(4) Filtration It is preferable to perform so-called breaker plate type filtration in which a filter medium is provided at the outlet of the extruder for filtering foreign matter in the resin and avoiding damage to the gear pump due to foreign matter. At this time, it can be achieved by adjusting the pore diameter of the filter medium and the flow rate of the molten resin as described above.

  In order to filter foreign matter with higher accuracy, it is preferable to provide a filtration device incorporating a so-called leaf type disk filter after passing through the gear pump. Filtration can be performed by providing one filtration section, or multistage filtration performed by providing a plurality of places. Although the filtration accuracy of the filter medium is preferably higher, the filtration accuracy is preferably 15 μm to 3 μmm, more preferably 10 μm to 3 μm, from the viewpoint of the pressure resistance of the filter medium and the increase in the filtration pressure due to clogging of the filter medium. In particular, when using a leaf-type disk filter device that finally filters foreign matter, it is preferable to use a filter medium with high filtration accuracy in terms of quality, and it is adjusted by the number of loaded sheets to ensure the suitability of pressure resistance and filter life. Is possible. The type of filter medium is preferably a steel material because it is used under high temperature and high pressure. Among steel materials, stainless steel, steel, etc. are particularly preferable, and stainless steel is particularly preferable in terms of corrosion. . As a configuration of the filter medium, for example, a sintered filter medium formed by sintering metal long fibers or metal powder can be used in addition to a knitted wire, and a sintered filter medium is preferable in terms of filtration accuracy and filter life.

(5) Gear pump In order to improve the thickness accuracy, it is important to reduce the fluctuation of the discharge amount. A gear pump is provided between the extruder and the die, and a certain amount of cellulose acylate resin is supplied from the gear pump. Is effective. A gear pump is accommodated in a state where a pair of gears consisting of a drive gear and a driven gear are engaged with each other, and the drive gear is driven to engage and rotate the two gears so that a melted state is generated from the suction port formed in the housing. Resin is sucked into the cavity, and a certain amount of the resin is discharged from a discharge port formed in the housing. Even if there is a slight fluctuation in the resin pressure at the front end of the extruder, the fluctuation is absorbed by using a gear pump, the fluctuation in the resin pressure downstream of the film forming apparatus becomes very small, and the thickness fluctuation is improved. By using a gear pump, it is possible to keep the fluctuation range of the resin pressure in the die portion 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. In addition, a high-precision gear pump using three or more gears that eliminates gear fluctuations of the gear pump is also effective.

  Other advantages of using a gear pump are that the pressure at the screw tip can be reduced to form a film, reducing energy consumption, preventing rise in resin temperature, improving transport efficiency, shortening the residence time in the extruder, L / D can be expected to be shortened. In addition, when using a filter to remove foreign matter, if there is no gear pump, the amount of resin supplied from the screw may fluctuate as the filtration pressure increases. It can be resolved. On the other hand, the disadvantages of gear pumps are that the length of the equipment becomes longer depending on the equipment selection method, the residence time of the resin becomes longer, and the shearing stress of the gear pump section may cause the molecular chain to break. is required.

  The preferred residence time of the resin from the supply port through the extruder until it exits the die is 2 minutes to 60 minutes, more preferably 3 minutes to 40 minutes, and even more preferably 4 minutes to 30 minutes. is there.

  The deterioration of the flow of the polymer for bearing circulation of the gear pump deteriorates the sealing by the polymer in the drive part and the bearing part, and the problem of increase in the metering and liquid feed extrusion pressure occurs. A gear pump design (especially clearance) that matches the melt viscosity is required. In some cases, the staying portion of the gear pump causes deterioration of the thermoplastic resin, so that a structure with as little staying as possible is preferable. The polymer pipes and adapters that connect the extruder and gear pump or gear pump and die also need to have a design with as little stagnation as possible, and to stabilize the extrusion pressure of thermoplastic resins with high temperature dependence of melt viscosity. It is preferable to make the temperature fluctuation as small as possible. Generally, a band heater having a low equipment cost is often used for heating the polymer tube, but it is more preferable to use an aluminum cast heater with less temperature fluctuation. Further, in the extruder as described above, it is preferable that the barrel of the extruder is heated and melted with a heater divided into 3 to 20.

(6) Die The thermoplastic resin is melted by the extruder configured as described above, and the molten resin is continuously sent to the die via a filter and a gear pump as necessary. As long as the die is designed so that the molten resin stays in the die, any type of commonly used T die, fishtail die, and hanger coat die may be used. There is no problem in placing a static mixer for improving the uniformity of the resin temperature immediately before the T die. The clearance at the T-die exit portion is generally 1.0 to 5.0 times the film thickness, preferably 1.2 to 3 times, and more preferably 1.3 to 2 times. When the lip clearance is 1.0 times smaller than the film thickness, it is difficult to obtain a good sheet by film formation. Further, when the lip clearance is larger than 5.0 times the film thickness, the sheet thickness accuracy is lowered, which is not preferable. The die is a very important facility for determining the thickness accuracy of the film, and a die capable of strictly controlling the thickness adjustment is preferable. Normally, the thickness can be adjusted at intervals of 40 to 50 mm, but preferably a type capable of adjusting the film thickness at intervals of 35 mm or less, more preferably at intervals of 25 mm or less. In addition, in order to improve the uniformity of the film-forming film, it is important to design the die with as little temperature unevenness as possible and unevenness in flow velocity in the width direction as much as possible. An automatic thickness adjustment die that measures the downstream film thickness, calculates the thickness deviation, and feeds back the result to the die thickness adjustment is also effective in reducing the thickness fluctuation in long-term continuous production.

  For production of a film, a single-layer film forming apparatus with a low equipment cost is generally used. However, in some cases, a film having two or more types of structures can also be manufactured using a multilayer film forming apparatus in order to provide a functional layer on an outer layer. Is possible. In general, the functional layer is preferably thinly laminated on the surface layer, but the layer ratio is not particularly limited.

(7) Casting Under the above conditions, the molten resin extruded from the die onto the sheet is cooled and solidified on the casting drum to obtain a film.

  In the present invention, 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 or the like on the casting drum to improve the adhesion between the casting drum and the melt-extruded sheet. It is preferable to use the touch roll method.

  In the touch roll method, a touch roll is placed on a cast drum to shape the film surface. At this time, the touch roll is preferably not elastic and usually elastic. However, if the elastically deformable member (rubber etc.) is covered with an extremely thin metal, the surface pressure cannot be increased (the deformation amount of the Tachiroll is large, the contact area with the cast roll becomes too large, and the sufficient surface pressure is reduced. It is not preferable because it cannot be used. The thickness of the touch roll of the present invention is 0.5 mm or more and 7 mm or less, more preferably 1.1 to 6 mm, and still more preferably 1.5 to 5 mm. The touch roll and casting roll preferably have a mirror surface, and the arithmetic average height Ra is 100 nm or less, preferably 50 nm or less, more preferably 25 nm or less. A preferable surface pressure of the touch roll is 0.1 MPa or more and 10 MPa or less, more preferably 0.2 MPa or more and 7 MPa or less, and further preferably 0.3 MPa or more and 5 MPa or less. The surface pressure referred to here is a value obtained by dividing the force pressing the touch roll by the contact area between the thermoplastic film and the touch roll.

  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. The temperature of the touch roll exceeds Tg-10 ° C and is preferably Tg + 30 ° C or less, more preferably Tg-7 ° C or more and Tg + 20 ° C or less, and further preferably Tg-5 ° C or more and Tg + 10 ° C or less. The temperature of the casting roll is preferably in the same temperature range.

  Specifically, for example, touch rolls described in JP-A-11-314263 and JP-A-11-235747 can be used as the touch roll.

  More preferably, a plurality of casting drums (rolls) are used for gradual cooling (among these, the touch roll is used so as to touch the first casting roll on the most upstream side (the one 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 50 mm to 5000 mm, more preferably 100 mm to 2000 mm, and still 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 line speed on the most upstream side of the cast roll is preferably 20 m / min or more and 70 m / min or less.

(8) Winding After peeling off from the casting drum, it winds up through a nip roll.

  The film forming width is 0.7 m to 5 m, more preferably 1 m to 4 m, and still more preferably 1.3 m to 3 m. The thickness of the unstretched film thus obtained is preferably 20 μm to 250 μm, more preferably 25 μm to 200 μm, still more preferably 30 μm to 180 μm.

  It is also preferable to trim both ends before winding. As the trimming cutter, any type of rotary cutter, shear blade, knife, or the like may be used. As for the material, either carbon steel or stainless steel may be used. In general, it is preferable to use a cemented carbide blade or a ceramic blade because the life of the blade is long and the generation of chips is suppressed. The portion cut off by trimming may be crushed and used again as a raw material.

  It is also preferable to perform a thickness increasing process (knurling process) at one or both ends. The height of the unevenness due to the thickness increasing process is preferably 1 μm to 200 μm, more preferably 10 μm to 150 μm, and still more preferably 20 μm to 100 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, and still more preferably 5 mm to 20 mm. Extrusion can be performed at room temperature to 300 ° C.

  The film thus formed may be stretched as it is (online stretching), or after being wound up, it may be sent out again and stretched (offline stretching).

  At the time of winding, it is also preferable to attach a lami film on at least one side from the viewpoint of preventing scratches. The thickness of the laminated film is preferably 5 μm to 200 μm, preferably 10 μm to 150 μm, and preferably 15 μm to 100 μm. The material is not particularly limited, such as polyethylene, polyester, and polypropylene.

  A preferable winding tension is 1 kg / m width to 50 kg / width, more preferably 2 kg / m width to 40 kg / width, and still more preferably 3 kg / m width to 20 kg / width. When the winding tension is smaller than 1 kg / m width, it is difficult to wind the film uniformly. On the other hand, when the winding tension exceeds 50 kg / width, the film becomes tightly wound, not only the appearance of the winding is deteriorated, but also the bump portion of the film extends due to the creep phenomenon, and the film wave This is not preferable because it causes a cause or residual birefringence due to the elongation of the film. The winding tension is preferably detected by tension control in the middle of the line and is wound while being controlled to have a constant winding tension. If there is a difference in film temperature depending on the location of the film production line, the length of the film may be slightly different due to thermal expansion. It is necessary to prevent tension.

  The winding tension can be wound at a constant tension by controlling the tension control. However, it is more preferable that the winding tension is tapered to an appropriate winding tension according to the wound diameter. Generally, the tension is gradually reduced as the winding diameter increases, but in some cases, it may be preferable to increase the tension as the winding diameter increases.

<< Extension process >>
The melt-formed cycloolefin film may be subjected to transverse stretching and longitudinal stretching, and may be subjected to relaxation treatment in combination with these. These can be implemented by, for example, the following combinations.
1.Transverse stretching
2.Horizontal stretching → relaxation treatment
3.Longitudinal stretching → Lateral stretching
4.Longitudinal stretching → transverse stretching → relaxation treatment
5.Longitudinal stretching → relaxation treatment → lateral stretching → relaxation treatment
6.Horizontal stretching → longitudinal stretching → relaxation treatment
7.Horizontal stretching → relaxation treatment → longitudinal stretching → relaxation treatment
8.Longitudinal stretching → transverse stretching → longitudinal stretching
9.Longitudinal stretching → transverse stretching → longitudinal stretching → relaxation treatment
10.longitudinal stretching
11. Longitudinal stretching → relaxation treatment Among these, 1 to 4 and 10 to 11 are more preferable, and 2, 4, and 11 are more preferable. Among these, 1 to 4 is more preferable, and 2 and 4 are more preferable.

  By performing the stretching of the present invention described below, the tail streaks of the present invention can be more efficiently reduced, and the elongation at break can be improved. When the film becomes thinner due to stretching, the thickness of the tail portion also decreases and the number decreases, but in the normal stretching method, the stretching stress tends to concentrate on weak areas, and the tail portion where the thickness is slightly thickened is stretched. Hateful. On the other hand, in the stretching method of the present invention, since a stretching stress can be applied uniformly in the plane, both the tail part and the normal part are stretched in the same manner, so that more efficient tail part failure can be reduced. Furthermore, by such uniform stretching, the molecules that have been rounded in the film can be efficiently stretched. As a result, entanglement can be formed between the molecules, and the breaking strength can be improved.

(Longitudinal stretching)
In the present invention, it is also preferable to carry out by combining transverse stretching and longitudinal stretching. In this case, it is more preferable to perform transverse stretching after longitudinal stretching.

  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 (referred to as aspect ratio) exceeds 2 and is 50 or less (long span stretching), Rth can be decreased, and when the aspect ratio 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 = L / W is more than 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.

(1-1) Long span stretching The film is stretched as it is stretched. At this time, the film is reduced in thickness and width in order to reduce the volume change. At this time, shrinkage in the width direction is limited by friction between the nip roll and the film. For this reason, when the nip roll interval is increased, shrinkage in the width direction is facilitated, and thickness reduction can be suppressed. When the thickness reduction is large, the same effect as that in which the film is compressed in the thickness direction is obtained. On the contrary, when the aspect ratio is large and the thickness reduction is small, Rth hardly appears and low Rth can be realized.

Furthermore, if the aspect ratio is long, the uniformity in the width direction can be improved. This is due to the following reason.
• The film tends to shrink in the width direction as it is stretched. At the central portion in the width direction, both sides thereof also try to contract in the width direction, so that it becomes a tug of war and cannot be contracted freely.
-On the other hand, the film width direction end part is in a tug-of-war state only with one side, and can contract relatively freely.
-The difference in shrinkage behavior associated with the stretching between both ends and the central portion becomes stretching unevenness in the width direction.

  Due to such non-uniformity between both ends and the center, retardation in the width direction and axial deviation (orientation angle distribution of slow axis) occur. On the other hand, since long span stretching is performed slowly between two long nip rolls, uniformity of these non-uniformities (uniform molecular orientation) proceeds during stretching. On the other hand, in normal longitudinal stretching (aspect ratio = more than 0.3 and less than 2), such homogenization does not occur.

  The aspect ratio is preferably more than 2 and 50 or less, more preferably 3 to 40, still more preferably 4 to 20. A preferred stretching temperature is (Tg-5 ° C) to (Tg + 100) ° C, more preferably (Tg) to (Tg + 50) ° C, and still more preferably (Tg + 5) to (Tg + 30) ° C. A preferable draw ratio is 1.05 to 3 times, more preferably 1.05 to 1.7 times, and still more preferably 1.05 to 1.4 times. 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. In the present invention, the zone heating method is preferable from the viewpoint of uniformity of the stretching temperature. At this time, the nip roll may be installed in the stretching zone or out of the zone, but it is preferably out of the zone in order to prevent the film and the nip roll from sticking. It is also preferable to preheat the film before such stretching, and the preheating temperature is Tg-80 ° C or higher and Tg + 100 ° C or lower.

  By such stretching, the Re value is 0 to 200 nm, more preferably 10 to 200 nm, further preferably 15 nm to 100 nm, the Rth value is 30 to 500 nm, more preferably 50 to 400 nm, and further preferably 70 to 350 nm. . By this stretching method, the ratio of Rth and Re (Rth / Re) can be 0.4 to 0.6, more preferably 0.45 to 0.55. A film having such characteristics can be used as an A plate type retardation plate. Furthermore, by this stretching, both the Re value and the Rth value can be 5% or less, more preferably 4% or less, and even more preferably 3% or less.

  With such stretching, the ratio of the film width before and after stretching (film width after stretching / film width before stretching) is 0.5 to 0.9, more preferably 0.6 to 0.85, more preferably 0.65 to 0.83.

(1-2) Short span stretching Longitudinal stretching with an aspect ratio (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 (Short span stretching) is performed. By performing stretching at an aspect ratio (L / W) in such a range, neck-in (shrinkage in the direction orthogonal to stretching accompanying stretching) can be reduced. Although the width and thickness are reduced to compensate for stretching in the stretching direction, such short span stretching suppresses width shrinkage and preferentially reduces the thickness. As a result, the film is compressed in the thickness direction, and the orientation (plane orientation) in the thickness direction proceeds. As a result, Rth, which is a measure of anisotropy in the thickness direction, tends to increase. On the other hand, conventionally, the aspect ratio (L / W) is generally about 1 (0.7 to 1.5). This is usually done by installing a heater for heating between the nip rolls, but if the L / W is too large, the film cannot be heated uniformly with the heater and uneven stretching tends to occur. If the L / W is too small, the heater is stretched. This is because it is difficult to install and cannot be heated sufficiently.

  The short span stretching described above can be carried out by changing the transport speed between two or more pairs of nip rolls, but unlike the normal roll arrangement, the two pairs of nip rolls are arranged obliquely (the rotation axes of the front and rear nip rolls are shifted up and down). This can be achieved. 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.

  The preferred stretching temperature is (Tg−5 ° C.) to (Tg + 100) ° C., more preferably (Tg) to (Tg + 50) ° C., still more preferably (Tg + 5) to (Tg + 30) ° C., and the preferred preheating temperature is Tg−. It is 80 degreeC or more and Tg + 100 degrees C or less.

(Lateral 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 stretching temperature is preferably Tg-10 ° C or higher and Tg + 60 ° C or lower, more preferably Tg-5 ° C or higher and Tg + 45 ° C or lower, and further preferably Tg or higher and Tg + 30 ° C or lower.

  By performing preheating before stretching and heat setting after stretching, the Re and Rth distribution after stretching can be reduced, and variations in orientation angles associated with bowing can be reduced. Either preheating or heat setting may be performed, but both are more preferable. These preheating and heat setting are preferably performed by holding with a clip, that is, preferably performed continuously with stretching.

  Preheating is preferably performed at 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 from 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.

  The heat setting is preferably 1 to 50 ° C., more preferably 2 to 40 ° C., more preferably 3 to 30 ° C. lower than the stretching temperature. 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 is likely to occur in the film, and it is not preferable because it is likely to increase the variation with time of Re and Rth.

  Thus, it is preferable that the heat setting temperature <the stretching temperature <the preheating temperature.

The reason why the variation in orientation angle and Re, Rth can be reduced by such preheating and heat setting is as follows.
The film is stretched in the width direction and tends to become thin (neck-in) in the orthogonal direction (longitudinal direction). For this reason, the film before and after transverse stretching is pulled and stress is generated. However, both ends in the width direction are fixed by chucks and are not easily deformed by stress, and the central portion in the width direction is easily deformed. As a result, the stress caused by the neck-in is deformed into a bow shape and bowing occurs. As a result, in-plane Re, Rth unevenness and distribution of orientation axes occur.
In order to suppress this, if the temperature on the preheating side (before stretching) is increased and the temperature on the heat treatment (after stretching) is lowered, neck-in occurs on the high temperature side (preheating) with a lower elastic modulus, and heat treatment ( It becomes difficult to occur after stretching). As a result, bowing after stretching can be suppressed.

  By such stretching, variations in the width direction and the longitudinal direction of Re and Rth can both be 5% or less, more preferably 4% or less, and even more preferably 3% or less. Further, the orientation angle can be 90 ° ± 5 ° or less or 0 ° ± 5 ° or less, more preferably 90 ° ± 3 ° or less, or 0 ° ± 3 ° or less, and further preferably 90 ° ± 1 ° or less or It can be 0 ° ± 1 ° or less.

  The present invention is characterized in that such an effect can be achieved even with high-speed stretching, and the effect is remarkably exhibited even at 20 m / min or more, more preferably 25 m / min or more, and even more preferably 30 m / min or more.

《Mitigation treatment》
Furthermore, dimensional stability can be improved by performing relaxation treatment after these stretching. The thermal relaxation is preferably performed after longitudinal stretching, either after lateral stretching, or both, and more preferably after lateral stretching. The relaxation treatment may be performed online continuously after stretching, or may be performed offline after winding after stretching.

  Thermal relaxation is Tg-30 ° C or higher and Tg + 30 ° C or lower, more preferably Tg-30 ° C or higher and Tg + 20 ° C or lower, more preferably Tg-15 ° C or higher and Tg + 10 ° C or lower, 1 second or longer and 10 minutes or shorter, more preferably 5 seconds or longer and 4 seconds. Min. Or less, more preferably 10 seconds or more and 2 minutes or less, 0.1 kg / m or more and 20 kg / m or less, more preferably 1 kg / m or more and 16 kg / m or less, more preferably 2 kg / m or more and 12 kg / m or less. However, it is preferable to carry out.

<Volatile components during stretching>
In the above longitudinal stretching and lateral stretching, the volatile components (solvent, moisture, etc.) are preferably 1 wt% or less, more preferably 0.5 wt% or less, still more preferably 0.3 wt% or less with respect to the resin. Thereby, the axial shift generated during stretching can be further reduced. This is because during the stretching, in addition to the shrinkage stress acting in the direction perpendicular to the stretching, the shrinkage stress accompanying drying acts, and the bowing becomes more prominent.

<Physical properties after stretching>
It is preferable that Re and Rth of the thermoplastic film thus longitudinally stretched, laterally stretched, and longitudinally and transversely satisfy the following formulas (R-1) and (R-2).
Formula (R-1): 0 nm ≦ Re ≦ 200 nm
Formula (R-2): 0 nm ≦ Rth ≦ 600 nm
(In the formula, Re represents the in-plane retardation of the thermoplastic film, and Rth represents the thickness direction retardation of the thermoplastic film.)
More preferably, Rth ≧ Re × 1.1
180 ≧ Re ≧ 10
400 ≧ Rth ≧ 50
More preferably, Rth ≧ Re × 1.2
150 ≧ Re ≧ 20
300 ≧ Rth ≧ 100
It is.

  The angle θ formed by the film forming direction (longitudinal direction) and the slow axis of Re of the film is preferably closer to 0 °, + 90 °, or −90 °. That is, in the case of longitudinal stretching, it is preferably as close to 0 °, preferably 0 ± 3 °, more preferably 0 ± 2 °, and further preferably 0 ± 1 °. In the case of transverse stretching, 90 ± 3 ° or −90 ± 3 ° is preferable, 90 ± 2 ° or −90 ± 2 ° is more preferable, and 90 ± 1 ° or −90 ± 1 ° is more preferable.

  The variation in Re and Rth is preferably 0% to 8%, more preferably 0% to 5%, and still more preferably 0% to 3%.

  Further, the Re and Rth fluctuations under storage (Re and Rth changes before and after 500 hours at 80 ° C .: details will be described later) are preferably 0% or more and 8% or less, more preferably 0% or more and 6% or less, Preferably they are 0% or more and 4% or less.

  As for the thickness of the thermoplastic film after extending | stretching, 15 micrometers-200 micrometers are all preferable, More preferably, they are 20 micrometers-120 micrometers, More preferably, they are 30 micrometers-80 micrometers. 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%. By using a thin film, residual strain is less likely to remain in the film after stretching, and retardation changes with time are less likely to occur. This is because when cooling after stretching, if the thickness is thick, the internal cooling is delayed compared to the surface, and residual strain due to the difference in heat shrinkage is likely to occur.

  The thermal dimensional change rate is preferably 0% or more and 0.5% or less, more preferably 0% or more and 0.3% or less, and further preferably 0% or more and 0.2% or less. The thermal dimensional change rate refers to a dimensional change when heat-treated at 80 ° C. for 5 hours (details will be described later).

<< Processing of cycloolefin film >>
The cycloolefin film of the present invention thus obtained may be used alone or in combination with a polarizing plate, and a liquid crystal layer or a layer with a controlled refractive index (low reflection layer) on these. ) Or a hard coat layer may be used. These can be achieved by the following steps.

(surface treatment)
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 performed 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.

  A plasma-excitable gas is a gas that is plasma-excited under the above-described conditions, and examples thereof include chlorofluorocarbons such as argon, helium, neon, krypton, xenon, nitrogen, carbon dioxide, tetrafluoromethane, and mixtures thereof. It is done. Details of these are described in detail on pages 30 to 32 in the Journal of the Invention Association (Technology No. 2001-1745, issued on March 15, 2001, Invention Association). Note that, in the plasma treatment at atmospheric pressure which has been attracting attention in recent years, for example, irradiation energy of 20 to 500 KGy is used under 10 to 1000 Kev, and more preferably irradiation energy of 20 to 300 KGy is used under 30 to 500 Kev.

  Of these, glow discharge treatment, corona treatment, and flame treatment are particularly preferred.

  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 (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.

(Grant functional layer)
The functional layer described in detail on pages 32 to 45 of the Japan Occupational Technology Association (Technology No. 2001-1745, published on March 15, 2001, Japan Institute of Invention) on the cycloolefin film of the present invention. It is preferable to combine them. Among these, application of a polarizing layer (polarizing plate), application of an optical compensation layer (optical compensation sheet), and application of an antireflection layer (antireflection film) are preferable.

(A) Application of polarizing layer (preparation of polarizing plate)
(A-1) Material used Currently, a commercially available polarizing layer is obtained by immersing a stretched polymer in a solution of iodine or dichroic dye in a bath and allowing iodine or dichroic dye to penetrate into the binder. It is common to make it. The polarizing film is manufactured by Optiva Inc. A coating type polarizing film typified by can also be used. Iodine and dichroic dye in the polarizing film exhibit deflection performance by being oriented in the binder. 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). For example, the compound as described in Invention Association public technique, public technical number 2001-1745, page 58 (issue date March 15, 2001) can be mentioned.

  As the binder for the polarizing film, either a polymer that can be crosslinked per se or a polymer that is crosslinked by a crosslinking agent can be used, and a plurality of combinations thereof can be used. Examples of the binder include methacrylate copolymer, styrene copolymer, polyolefin, polyvinyl alcohol and modified polyvinyl alcohol, poly (N-methylolacrylamide) described in paragraph No. [0022] of JP-A-8-338913. , Polyester, polyimide, vinyl acetate copolymer, carboxymethyl cellulose, polycarbonate and the like. Silane coupling agents can be used as the polymer. Among these, water-soluble polymers (eg, poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol, and modified polyvinyl alcohol) are preferable, gelatin, polyvinyl alcohol, and modified polyvinyl alcohol are more preferable, and polyvinyl alcohol and modified polyvinyl alcohol are preferable. Is most preferred. It is particularly preferable to use two types of polyvinyl alcohol or modified polyvinyl alcohol having different degrees of polymerization. The saponification degree of polyvinyl alcohol is preferably 70 to 100%, more preferably 80 to 100%. It is preferable that the polymerization degree of polyvinyl alcohol is 100-5000. The modified polyvinyl alcohol is described in JP-A-8-338913, JP-A-9-152509 and JP-A-9-316127. Two or more kinds of polyvinyl alcohol and modified polyvinyl alcohol may be used in combination.

  The lower limit of the binder thickness is preferably 10 μm. The upper limit of the thickness is preferably as thin as possible from the viewpoint of light leakage of the liquid crystal display device. It is preferably not more than a commercially available polarizing plate (about 30 μm), preferably 25 μm or less, and more preferably 20 μm or less.

  The binder of the polarizing film may be cross-linked. A polymer or monomer having a crosslinkable functional group may be mixed in the binder, or a crosslinkable functional group may be imparted to the binder polymer itself. Crosslinking can be performed by light, heat, or pH change, and a binder having a crosslinked structure can be formed. The crosslinking agent is described in US Reissue Patent 23297. Boron compounds (eg, boric acid, borax) can also be used as a crosslinking agent. The addition amount of the crosslinking agent in the binder is preferably 0.1 to 20% by mass with respect to the binder. The orientation of the polarizing element and the wet heat resistance of the polarizing film are improved.

  Even after the crosslinking reaction is completed, the unreacted crosslinking agent is preferably 1.0% by mass or less, and more preferably 0.5% by mass or less. By doing in this way, a weather resistance improves.

(A-2) Stretching of polarizing layer The polarizing film is preferably dyed with iodine or a dichroic dye after stretching the polarizing film (stretching method) or rubbing (rubbing method).

  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. Stretching may be performed in parallel to the MD direction (parallel stretching), or may be performed in an oblique direction (oblique stretching). These stretching operations may be performed once or divided into several times. By dividing into several times, it is possible to stretch more uniformly even at high magnification.

a) Parallel stretch method Prior to stretching, the PVA film is swollen. The degree of swelling is 1.2 to 2.0 times (mass ratio before swelling and after swelling). Thereafter, the film is stretched at a bath temperature of 15 to 50 ° C., particularly 17 to 40 ° C. in an aqueous medium bath or a dye bath for dissolving a dichroic substance while being continuously conveyed through a guide roll or the like. Stretching can be achieved by gripping with two pairs of nip rolls and increasing the conveyance speed of the subsequent nip roll to be higher than that of the previous nip roll. The draw ratio is based on the length ratio after stretching / initial state (hereinafter the same), but the preferred draw ratio is 1.2 to 3.5 times, especially 1.5 to 3.0 times from the viewpoint of the above-mentioned effects. is there. Thereafter, the film is dried at 50 ° C. to 90 ° C. to obtain a polarizing film.

b) Diagonal Stretching Method For this purpose, a method of stretching using a tenter projecting in an obliquely inclined direction as described in JP-A-2002-86554 can be used. Since this stretching is performed in the air, it is necessary to make it easy to stretch by adding water in advance. The preferred water content is 5% to 100%, more preferably 10% to 100%.

  The temperature during stretching is preferably 40 ° C to 90 ° C, more preferably 50 ° C to 80 ° C. The relative humidity is preferably 50% to 100%, more preferably 70% to 100% relative humidity, and still more preferably 80% to 100% relative humidity. The traveling speed in the longitudinal direction is preferably 1 m / min or more, more preferably 3 m / min or more.

  After the completion of stretching, the film is dried at 50 ° C to 100 ° C, more preferably 60 ° C to 90 ° C for 0.5 minutes to 10 minutes. More preferably, it is 1 minute to 5 minutes.

  The absorption axis of the polarizing film thus obtained is preferably 10 ° to 80 °, more preferably 30 ° to 60 °, and still more preferably 45 ° (40 ° to 50 °).

(I-3) Bonding A polarizing plate is prepared by bonding the thermoplastic film after the surface treatment and a polarizing layer prepared by stretching. The laminating direction is preferably such that the casting axis direction of the thermoplastic film and the stretching axis direction of the polarizing plate are 45 °.

  The adhesive for bonding is not particularly limited, but examples thereof include PVA resins (including modified PVA such as acetoacetyl group, sulfonic acid group, carboxyl group, oxyalkylene group) and boron compound aqueous solution. preferable. The thickness of the adhesive layer is preferably 0.01 to 10 μm after drying, and particularly preferably 0.05 to 5 μm.

  The polarizing plate thus obtained preferably has a higher light transmittance, and preferably has a higher degree of polarization. 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 most preferably in the range of 40 to 50% in light having a wavelength of 550 nm. . 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.

  Furthermore, the polarizing plate thus obtained can be laminated with a λ / 4 plate to produce circularly polarized light. In this case, lamination is performed so that the slow axis of λ / 4 and the absorption axis of the polarizing plate are 45 degrees. At this time, λ / 4 is not particularly limited, but more preferably has a wavelength dependency such that the lower the wavelength, the smaller the retardation. Furthermore, it is preferable to use a polarizing film having an absorption axis inclined by 20 ° to 70 ° with respect to the longitudinal direction and a λ / 4 plate made of an optically anisotropic layer made of a liquid crystalline compound.

(B) Application of optical compensation layer (production of optical compensation sheet)
The optically anisotropic layer is for compensating for the liquid crystal compound in the liquid crystal cell in the black display of the liquid crystal display device, and forms an alignment film on the thermoplastic film of the present invention. It is formed by giving.

(B-1) Alignment film An alignment film is provided on the surface-treated thermoplastic film. This film has a function of defining the alignment direction of liquid crystalline molecules. However, if the alignment state is fixed after aligning the liquid crystalline compound, the alignment film plays the role, and thus is not necessarily an essential component of the present invention. That is, it is possible to produce the polarizing plate of the present invention by transferring only the optically anisotropic layer on the alignment film in which the alignment state is fixed onto the polarizer.

  The alignment film is an organic compound (eg, ω-tricosanoic acid) formed by rubbing treatment of an organic compound (preferably polymer), oblique deposition of an inorganic compound, formation of a layer having a microgroove, or Langmuir-Blodgett method (LB film). , Dioctadecylmethylammonium chloride, methyl stearylate). Furthermore, an alignment film in which an alignment function is generated by application of an electric field, application of a magnetic field, or light irradiation is also known.

  The alignment film is preferably formed by polymer rubbing treatment. In principle, the polymer used for the alignment film has a molecular structure having a function of aligning liquid crystal molecules.

  In the present invention, in addition to the function of aligning liquid crystalline molecules, a cross-linking having a function of aligning a side chain having a crosslinkable functional group (eg, double bond) to the main chain or aligning liquid crystalline molecules. It is preferable to introduce a functional functional group into the side chain.

  As the polymer used in the alignment film, either a polymer that can be crosslinked by itself or a polymer that is crosslinked by a crosslinking agent can be used, and a plurality of combinations thereof can be used. Examples of the polymer include methacrylate copolymers, styrene copolymers, polyolefins, polyvinyl alcohol and modified polyvinyl alcohol, poly (N-methylol) described in paragraph No. [0022] of JP-A-8-338913. Acrylamide), polyester, polyimide, vinyl acetate copolymer, carboxymethylcellulose, polycarbonate and the like. Silane coupling agents can be used as the polymer. Water-soluble polymers (eg, poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol, 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. . It is particularly preferable to use two types of polyvinyl alcohol or modified polyvinyl alcohol having different degrees of polymerization. The saponification degree of polyvinyl alcohol is preferably 70 to 100%, more preferably 80 to 100%. It is preferable that the polymerization degree of polyvinyl alcohol is 100-5000.

  A side chain having a function of aligning liquid crystal molecules generally has a hydrophobic group as a functional group. The specific type of functional group is determined according to the type of liquid crystal molecule and the required alignment state. For example, the modifying group of the modified polyvinyl alcohol can be introduced by copolymerization modification, chain transfer modification or block polymerization modification. Examples of modifying groups include hydrophilic groups (carboxylic acid groups, sulfonic acid groups, phosphonic acid groups, amino groups, ammonium groups, amide groups, thiol groups, etc.), hydrocarbon groups having 10 to 100 carbon atoms, fluorine atoms Substituted hydrocarbon groups, thioether groups, polymerizable groups (unsaturated polymerizable groups, epoxy groups, azirinidyl groups, etc.), alkoxysilyl groups (trialkoxy, dialkoxy, monoalkoxy) and the like can be mentioned. As specific examples of these modified polyvinyl alcohol compounds, for example, paragraph numbers [0022] to [0145] in JP-A No. 2000-155216 and paragraph numbers [0018] to [0018] in JP-A No. 2002-62426 are described. [0022] and the like.

  When a side chain having a crosslinkable functional group is bonded to the main chain of the alignment film polymer, or a crosslinkable functional group is introduced into a side chain having a function of aligning liquid crystalline molecules, the alignment film polymer and the optically anisotropic film The polyfunctional monomer contained in the conductive layer can be copolymerized. As a result, not only between the polyfunctional monomer and the polyfunctional monomer, but also between the alignment film polymer and the alignment film polymer and between the polyfunctional monomer and the alignment film polymer is firmly bonded by a covalent bond. Therefore, the strength of the optical compensation sheet can be remarkably improved by introducing the crosslinkable functional group into the alignment film polymer.

  The crosslinkable functional group of the alignment film polymer preferably contains a polymerizable group in the same manner as the polyfunctional monomer. Specific examples include those described in paragraphs [0080] to [0100] in JP-A-2000-155216. Apart from the crosslinkable functional group, the alignment film polymer can also be crosslinked using a crosslinking agent.

  Examples of the crosslinking agent include aldehydes, N-methylol compounds, dioxane derivatives, compounds that act by activating carboxyl groups, active vinyl compounds, active halogen compounds, isoxazole, and dialdehyde starch. Two or more kinds of crosslinking agents may be used in combination. Specific examples include compounds described in paragraphs [0023] to [0024] in JP-A-2002-62426. Aldehydes having high reaction activity, particularly glutaraldehyde are preferred.

  0.1-20 mass% is preferable with respect to the said polymer, and, as for the addition amount of a crosslinking agent, 0.5-15 mass% is more preferable. The amount of the unreacted crosslinking agent remaining in the alignment film is preferably 1.0% by mass or less, and more preferably 0.5% by mass or less. By adjusting in this way, even if the alignment film is used for a long time in a liquid crystal display device or left in a high temperature and high humidity atmosphere for a long time, sufficient durability without reticulation can be obtained. May occur.

  The alignment film can be basically formed by applying the polymer, which is an alignment film forming material, on a transparent support containing a crosslinking agent, followed by heat drying (crosslinking) and rubbing treatment. As described above, the crosslinking reaction may be performed at any time after coating on the transparent support. When a water-soluble polymer such as polyvinyl alcohol is used as the alignment film forming material, the coating liquid is preferably a mixed solvent of an organic solvent (eg, methanol) having a defoaming action and water. The ratio of water: methanol is preferably 0: 100 to 99: 1, and more preferably 0: 100 to 91: 9. Thereby, generation | occurrence | production of a bubble is suppressed and the defect of the layer surface of an alignment film and also an optical anisotropic layer reduces remarkably.

  The alignment film is preferably applied by spin coating, dip coating, curtain coating, extrusion coating, rod coating, or roll coating. A rod coating method is particularly preferable. The film thickness after drying is preferably 0.1 to 10 μm. Heating and drying can be performed at 20 ° C to 110 ° C. In order to form sufficient cross-linking, 60 ° C to 100 ° C is preferable, and 80 ° C to 100 ° C is particularly preferable. The drying time can be 1 minute to 36 hours, preferably 1 minute to 30 minutes. The pH is preferably set to an optimum value for the crosslinking agent to be used. When glutaraldehyde is used, the pH is 4.5 to 5.5, and 5 is particularly preferable.

  The alignment film is provided on the transparent support or the undercoat layer. The alignment film can be obtained by rubbing the surface after crosslinking the polymer layer as described above.

  For the rubbing treatment, a treatment method widely adopted as a liquid crystal alignment treatment process of LCD can be applied. That is, a method of obtaining the orientation by rubbing the surface of the orientation film in a certain direction using paper, gauze, felt, rubber, nylon, polyester fiber or the like can be used. Generally, it is carried out by rubbing several times using a cloth or the like in which fibers having a uniform length and thickness are planted on average.

  When industrially implemented, this is achieved by bringing a rotating rubbing roll into contact with the film with the polarizing layer being transported. However, the roundness, cylindricity, and deflection (eccentricity) of the rubbing roll can be any. Is preferably 30 μm or less. The film wrap angle on the rubbing roll is preferably 0.1 to 90 °. However, as described in JP-A-8-160430, a stable rubbing treatment can be obtained by winding 360 ° or more. As for the conveyance speed of a film, 1-100 m / min is preferable. It is preferable to select an appropriate rubbing angle in the range of 0 to 60 °. When used in a liquid crystal display device, 40 to 50 ° is preferable, and 45 ° is particularly preferable.

  The thickness of the alignment film thus obtained is preferably in the range of 0.1 to 10 μm.

  Next, the liquid crystalline molecules of the optically anisotropic layer are aligned on the alignment film. Thereafter, as necessary, the alignment film polymer and the polyfunctional monomer contained in the optically anisotropic layer are reacted, or the alignment film polymer is crosslinked using a crosslinking agent.

  The liquid crystalline molecules used in the optically anisotropic layer include rod-like liquid crystalline molecules and discotic liquid crystalline molecules. The rod-like liquid crystal molecules and the disk-like liquid crystal molecules may be high-molecular liquid crystals or low-molecular liquid crystals, and further include those in which low-molecular liquid crystals are cross-linked and no longer exhibit liquid crystallinity.

(B-2) Rod-like liquid crystalline molecules As rod-like liquid crystalline molecules, azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano substitution Phenylpyrimidines, alkoxy-substituted phenylpyrimidines, phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used.

  The rod-like liquid crystalline molecule includes a metal complex. In addition, a liquid crystal polymer containing a rod-like liquid crystalline molecule in a repeating unit can also be used as the rod-like liquid crystalline molecule. In other words, the rod-like liquid crystal molecule may be bonded to a (liquid crystal) polymer.

  For rod-like liquid crystalline molecules, see Chapter 4, Chapter 7 and Chapter 11 of the Chemistry of the Quarterly Chemistry Vol. 22 (1994) The Chemical Society of Japan, and the 142th Committee of the Japan Society for the Promotion of Science. Described in Chapter 3.

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

  The rod-like liquid crystalline molecule preferably has a polymerizable group in order to fix its alignment state. The polymerizable group is preferably a radically polymerizable unsaturated group or a cationically polymerizable group. Specifically, for example, the polymerizable groups described in paragraphs [0064] to [0086] of JP-A-2002-62427 are described. Group and a polymerizable liquid crystal compound.

(B-3) Discotic liquid crystalline molecules Discotic liquid crystalline molecules include C.I. Destrade et al., Mol. Cryst. 71, 111 (1981), benzene derivatives described in C.I. Destrade et al., Mol. Cryst. 122, 141 (1985), Physics lett, A, 78, 82 (1990); Kohne et al., Angew. Chem. 96, page 70 (1984) and the cyclohexane derivatives described in J. Am. M.M. Lehn et al. Chem. Commun. , 1794 (1985), J. Am. Zhang et al., J. Am. Chem. Soc. 116, 2655 (1994), azacrown type and phenylacetylene type macrocycles are included.

  As a discotic liquid crystalline molecule, a compound having liquid crystallinity 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 Is also included. The molecule or the assembly of molecules is preferably a compound having rotational symmetry and imparting a certain orientation. In the optically anisotropic layer formed from the discotic liquid crystalline molecules, the compound finally contained in the optically anisotropic layer does not need to be a discotic liquid crystalline molecule. 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 molecules are described in JP-A-8-50206. The polymerization of discotic liquid crystalline molecules is described in JP-A-8-27284.

  In order to fix the discotic liquid crystalline molecules by polymerization, it is necessary to bond a polymerizable group as a substituent to the discotic core of the discotic liquid crystalline molecules. A compound in which the discotic core and the polymerizable group are bonded via a linking group is preferable, whereby the orientation state can be maintained even in the polymerization reaction. Examples thereof include compounds described in paragraphs [0151] to “0168” in JP-A No. 2000-155216.

  In the hybrid alignment, the angle between the major axis (disk surface) of the discotic liquid crystalline molecule and the surface of the polarizing film increases or decreases in the depth direction of the optically anisotropic layer and with increasing distance from the surface of the polarizing film. is doing. The angle preferably decreases with increasing distance. Further, the change in angle can be a continuous increase, a continuous decrease, an intermittent increase, an intermittent decrease, a change including a continuous increase and a continuous decrease, or an intermittent change including an increase and a decrease. The intermittent change includes a region where the inclination angle does not change in the middle of the thickness direction. Even if the angle includes a region where the angle does not change, the angle only needs to increase or decrease as a whole. Furthermore, it is preferable that the angle changes continuously.

  The average direction of the major axis of the discotic liquid crystalline molecules on the polarizing film side can be generally adjusted by selecting a discotic liquid crystalline molecule or an alignment film material, or by selecting a rubbing treatment method. In addition, the major axis (disk surface) direction of the surface-side (air-side) discotic liquid crystalline molecules is generally adjusted by selecting the type of additive used together with the discotic liquid crystalline molecules or discotic liquid crystalline molecules. be able to. Examples of the additive used together with the discotic liquid crystalline molecule include a plasticizer, a surfactant, a polymerizable monomer and a polymer. The degree of change in the orientation direction of the major axis can be adjusted by selecting liquid crystal molecules and additives as described above.

(B-4) Other composition of optically anisotropic layer Along with the above liquid crystalline molecules, a plasticizer, a surfactant, a polymerizable monomer, etc. are used in combination, and the uniformity of the coating film, the strength of the film, and the liquid crystal Molecular orientation and the like can be improved. It is preferable that the compound has compatibility with the liquid crystal molecules and can change the tilt angle of the liquid crystal molecules or does not inhibit the alignment.

  Examples of the polymerizable monomer include radically polymerizable or cationically polymerizable compounds. Preferably, it is a polyfunctional radically polymerizable monomer and is preferably copolymerizable with the polymerizable group-containing liquid crystal compound. Examples thereof include those described in paragraph numbers [0018] to [0020] in JP-A No. 2002-296423. 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 molecules.

  Examples of the surfactant include conventionally known compounds, and fluorine compounds are particularly preferable. Specific examples include compounds described in paragraph numbers [0028] to [0056] in JP-A-2001-330725.

  The polymer used together with the discotic liquid crystalline molecule is preferably capable of changing the tilt angle of the discotic liquid crystalline molecule.

  A cellulose ester can be mentioned as an example of a polymer. Preferable examples of the cellulose ester include those described in paragraph [0178] of JP-A No. 2000-155216. The addition amount of the polymer is preferably in the range of 0.1 to 10% by mass, and preferably in the range of 0.1 to 8% by mass with respect to the liquid crystal molecule so as not to disturb the alignment of the liquid crystal molecules. It is more preferable.

  The discotic nematic liquid crystal phase-solid phase transition temperature of the discotic liquid crystalline molecules is preferably 70 to 300 ° C, more preferably 70 to 170 ° C.

(B-5) Formation of optically anisotropic layer The optically anisotropic layer is coated with a coating liquid containing liquid crystalline molecules and, if necessary, a polymerizable initiator and an optional component described later on the alignment film. Can be formed.

  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.

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

  The thickness of the optically anisotropic layer is preferably 0.1 to 20 μm, more preferably 0.5 to 15 μm, and most preferably 1 to 10 μm.

(B-6) Fixing of alignment state of liquid crystalline molecules The aligned liquid crystalline 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 the photopolymerization initiator include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ether (described in US Pat. No. 2,448,828), α-hydrocarbon substituted aromatic acyloin. Compound (described in US Pat. No. 2,722,512), polynuclear quinone compound (described in US Pat. Nos. 3,046,127 and 2,951,758), a combination of triarylimidazole dimer and p-aminophenyl ketone (US Pat. No. 3,549,367) Acridine and phenazine compounds (JP-A-60-105667, U.S. Pat. No. 4,239,850) and oxadiazole compounds (U.S. Pat. No. 4,212,970).

  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 20~5000mJ / cm ^2, more preferably in the range of 100 to 800 mJ / cm ² . 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.

  It is also preferable to combine this optical compensation film and a polarizing layer. Specifically, the optically anisotropic layer is formed by applying the coating liquid for the optically anisotropic layer as described above to the surface of the polarizing film. As a result, without using a polymer film between the polarizing film and the optically anisotropic layer, a thin polarizing plate having a small stress (strain × cross-sectional area × elastic modulus) associated with the dimensional change of the polarizing film is produced. . When the polarizing plate according to the present invention is attached to a large liquid crystal display device, an image with high display quality can be displayed without causing problems such as light leakage.

  The inclination angle between the polarizing layer and the optical compensation layer should be 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. Is preferred. A normal inclination angle is 45 °. Recently, however, devices that are not necessarily 45 ° have been developed in transmissive, reflective, and transflective LCDs, and it is preferable that the stretching direction can be arbitrarily adjusted according to the design of the LCD.

(B-7) Liquid crystal display device Each liquid crystal mode in which such an optical compensation film is used will be described.

(TN mode liquid crystal display)
The TN mode liquid crystal display device 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 the rod-like liquid crystalline molecules rise at the center of the cell and the rod-like liquid crystalline molecules lie in the vicinity of the cell substrate.

(OCB mode liquid crystal display)
The OCB mode liquid crystal display device is a bend alignment mode liquid crystal cell in which rod-like liquid crystal molecules are aligned (symmetrically) in substantially opposite directions at the upper and lower portions 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 molecules 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. For this reason, this liquid crystal mode is also 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 crystalline molecules rise at the center of the cell and the rod-like liquid crystalline molecules lie near the cell substrate. .

(VA mode liquid crystal display device)
The VA mode liquid crystal display device is characterized in that the rod-like liquid crystalline molecules are aligned substantially vertically when no voltage is applied. (1) No voltage is applied to the VA mode liquid crystal cell. In addition to a narrowly-defined VA mode liquid crystal cell (described in JP-A-2-176625), which is sometimes aligned substantially vertically and aligned substantially horizontally when a voltage is applied, Liquid crystal cell with multi-domain mode (MVA mode) (described in SID97, Digest of tech. Papers 28 (1997) 845), (3) Substantially vertical alignment of rod-like liquid crystalline molecules when no voltage is applied (N-ASM mode) liquid crystal cell (described in the proceedings 58-59 (1998) of the Japanese Liquid Crystal Society) and (4 The liquid crystal cell of SURVAIVAL mode (published in LCD International 98) are included.

(IPS mode liquid crystal display)
The IPS mode liquid crystal display device is characterized in that rod-like liquid crystalline molecules are substantially aligned horizontally in a plane when no voltage is applied, and this is switched by changing the alignment direction of the liquid crystal with or without voltage application. Is the feature. Specifically, JP 2004-365951 A, JP 2004-12731 A, JP 2004-215620 A, JP 2002-221726 A, JP 2002-55341 A, JP 2003-195333 A. Those described in the publication can be used.

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

(C) Application of an antireflection layer (antireflection film)
The antireflection film generally includes 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 (that is, a high refractive index layer and a medium refractive index layer). It is provided above.

  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 also mentioned.

  The thermoplastic 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 constituent composition of the hard coat layer include those described in JP-A Nos. 2002-144913, 2000-9908, and International Publication WO0 / 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-A-2000-281410, 2000-95893, 2001-100004, 2001-281407, etc.), uppermost layer (antifouling layer) And 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.

  Experiments were conducted using ZEONOR ZF-14 (manufactured by Nippon Zeon Co., Ltd.), TOPAS 6031, and 5031 (manufactured by Polyplastics Co.) listed in Table 1.

(Tg measurement)
20 mg of sample is placed in a DSC measuring pan. This is 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 is raised again from 30 ° C. to 250 ° C. (2nd-run). The temperature at which the baseline starts to deviate from the low temperature side in 2nd-run is shown in Table 1 as the glass transition temperature (Tg). Moreover, 0.05 mass% of silicon dioxide part particles (Aerosil R972V) were added to all levels.

[Melting film formation]
The cyclic polyolefin resin shown in Table 1 was blown and dried at 120 ° C. for 3 hours to adjust the water content to 0.1% by mass. To this, 3 wt% of triphenyl phosphate (TPP) as a plasticizer, 0.05 mass% of silicon dioxide part particles (Aerosil R972V), 0.20 mass% of phosphite stabilizer (P-1), "UV absorption Agent a "2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-tert-butylanilino) -1,3,5-triazine (0.8% by mass)," UV Absorber b "2 (2'-hydroxy-3 ', 5'-di-tert-butylphenyl) -5-chlorobenzotriazole (0.25 wt%) is added and the mixture is used in a twin screw kneader extruder And kneaded at 260 ° C. The biaxial kneading extruder was provided with a vacuum vent and evacuated (set to 0.3 atm). It was extruded into a strand having a diameter of 3 mm in a water bath and cut into a length of 5 mm.

  The kneaded resin is dried for 3 hours using dehumidified air at 90 ° C., and the moisture content is adjusted to 0.1 wt%. Then, a full flight screw with L / D = 35, a compression rate of 3.5, and a screw diameter of 65 mm is used. After melting at 260 ° C. using the inserted single-screw extruder, a certain amount was sent out using a gear pump in order to increase the thickness accuracy. The molten polymer sent out from the gear pump passes through a 4 μm sintered filter to remove foreign matter, and then sent out to a die having a slit-like gap, and cooled and solidified with a cooling roll to become a cyclic polyolefin resin film. . The solidified sheet was peeled off from the cooling roll and wound into a roll. The cooling roll was a metal roller having a diameter of 500 mm, a wall thickness of 25 mm, and a surface roughness Ra = 25 nm (however, Example 5 was 100 nm), and the set temperature was 120 ° C. The elastic roll was a metal roller having a diameter of 300 mm, a wall thickness of 0.3 mm, and a surface roughness Ra = 25 nm, and the set temperature was 120 ° C. Here, the film was formed such that the linear pressure P between the cooling roll and the elastic roll was 40 kg / cm, and the thickness of the sheet was 80 μm. In addition, both ends (each 3% of the total width) were trimmed immediately before winding.

  The unstretched film thus produced was measured for retardation values (Re and Rth), observed for streak failure, and measured for haze. The results are summarized in Table 1. Moreover, comprehensive evaluation was performed from these results.

(I) Film thickness unevenness (Rmax)
The obtained unstretched film 1000 m was measured with a continuous thickness meter, and the difference between the maximum thickness and the minimum thickness was determined. Rmax of less than ± 1.5 μm was evaluated as ◯, ± 1.5 μm or more and less than ± 2.0 μm was evaluated as Δ, and ± 2.0 μm or more was evaluated as ×.

(Ii) Retardation value (Re and Rth)
After sampling 10 points at equal intervals in the width direction of the unstretched film and adjusting the humidity for 4 hours at 25 ° C. and 60% rh, an automatic birefringence meter (KOBRA-21ADH: manufactured by Oji Scientific Instruments) was used. At 25 ° C. and 60% RH at a wavelength of 590 nm from the direction perpendicular to the sample film surface and the slow axis as the rotation axis from the film surface normal to + 50 ° to −50 ° in increments of 10 °. The phase difference value was measured.

(Iii) Observation of streak failure The appearance of the obtained unstretched film was visually inspected. ○ that shows no streak at all, △ shows that there is a very thin streak but there is no practical problem, × shows that there is a thin streak and is problematic in practical use, and streak at a glance What was understood was evaluated in XX and 4 levels.

(Iv) Measurement of haze The obtained unstretched film was measured using a turbidimeter NDH-1001DP manufactured by Nippon Color Industrial Co., Ltd.

  Note that the die edge width in Table 1 is obtained by collecting a replica of the edge portion of the die and observing it with a microscope.

As can be seen from Table 1 in FIG. 5, in Examples 1 to 6, the lip clearance (lip gap) of the die is in the range of 0.2 to 1.0 mm, and the resin flow rate per unit area at the die extrusion port is 1. Since the range is 0.1 to 1.5 kg / mm ² per hour, the film thickness unevenness is small compared to Comparative Example 1 and Comparative Example 2 which are not set in the range, and the result is good.

  Further, in Examples 1 to 6, in Example 4 where the R chamfering of the edge portion of the die or the C chamfering (die edge width in Table 1) is not within the range of 30 μm or less, streak failure is observed, and the overall evaluation is Δ. there were.

The schematic diagram which shows the structure of the film manufacturing apparatus with which this invention is applied Schematic showing the configuration of the extruder Schematic showing the die in the present invention Schematic showing the film forming process section Explanatory drawing of the Example of this invention

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Film manufacturing apparatus, 12 ... Cyclic polyolefin 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 24A ... slit, 24B ... lip land, 24C ... die lip, 24D ... die edge, 25 ... backup roller, 26 ... polishing roller (elastic roll), 27 ... thickness measuring means, 28 ... polishing roller (cooling roll), DESCRIPTION OF SYMBOLS 29 ... Elastic roll control means, 44 ... Outer cylinder, 46 ... Liquid medium layer, 48 ... Elastic body layer, 50 ... Metal shaft, d ... Lip clearance

Claims (9)

Melting cyclic polyolefin resin and extruding it from the die into a sheet,
Cyclic polyolefin-based resin film formed by cooling and solidifying the sheet by sandwiching the sheet between a pair of rollers having an arithmetic average height Ra of 100 nm or less and at least one roll formed of a metal elastic roll A manufacturing method of
While setting the lip clearance of the die in the range of 0.2 to 1.0 mm,
A method for producing a cyclic polyolefin-based resin film, wherein a resin flow rate per unit area at a die extrusion port is set in a range of 0.1 to 1.5 kg / mm ² per hour.   The method for producing a cyclic polyolefin-based resin film according to claim 1, wherein the edge chamfering or chamfering of the edge portion of the die is 30 µm or less.   The center line average roughness Ra of the die lip surface of the die is 0.5 µm or less, The method for producing a cyclic polyolefin resin film according to claim 1 or 2.   The method for producing a cyclic polyolefin resin film according to any one of claims 1 to 3, wherein the die lip surface of the die has a Vickers hardness of 500 or more.   The method for producing a cyclic polyolefin resin film according to any one of claims 1 to 4, wherein the cyclic polyolefin resin when discharged from the die has a zero shear viscosity of 2000 Pa · sec or less.   The cyclic polyolefin resin film according to claim 1, wherein the film thickness is 20 to 300 μm, the in-plane retardation Re is 20 nm or less, and the retardation Rth in the thickness direction is 20 nm or less. Manufacturing method.   A cyclic polyolefin resin film produced by the production method according to claim 1.   An optical compensation film for a liquid crystal display panel comprising the cyclic polyolefin resin film according to claim 7 as a base material.   A polarizing plate formed by using at least one sheet of the cyclic polyolefin resin film according to claim 7 as a protective film for a polarizing film (layer).

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