WO2013140728A1

WO2013140728A1 - Method for manufacturing long stretched film

Info

Publication number: WO2013140728A1
Application number: PCT/JP2013/001421
Authority: WO
Inventors: 大介北條; 真治稲垣; 晋平畠山; 大輔植野; 博南部
Original assignee: コニカミノルタ株式会社
Priority date: 2012-03-21
Filing date: 2013-03-06
Publication date: 2013-09-26
Also published as: JP5983732B2; JPWO2013140728A1

Abstract

This method for manufacturing a long stretched film has a long film formation step, an oblique stretching step, and a winding step, an oblique stretching device has a heating furnace and a gripper travel support tool, and the stretching direction of the oblique stretching device can be arbitrarily changed, the gripper travel support tool is provided with a drive shaft, and in the oblique stretching step, a long film is continuously heated by a planar heater provided between the drive shaft and the long film in at least a stretching zone inside the heating furnace.

Description

Manufacturing method of long stretched film

The present invention relates to a method for producing a long stretched film.

A stretched film formed by stretching a resin is used as an optical film that performs various optical functions in various display devices by utilizing its optical anisotropy. For example, in a liquid crystal display device, the stretched film is used as an optical compensation film for optical compensation such as anti-coloring and viewing angle expansion, or by bonding the stretched film and a polarizer, It is known to use as a retardation film that also serves as a polarizing plate protective film.

On the other hand, in recent years, a self-luminous display device such as an organic electroluminescence display device (hereinafter also referred to as an organic EL display) has attracted attention as a new display device. The self-luminous display device has a room for suppressing power consumption with respect to a liquid crystal display device whose backlight is always lit, and further, a self-luminous type in which a light source corresponding to each color such as an organic EL display is lit. In the display device, since it is not necessary to install a color filter that causes a reduction in contrast, the contrast can be further increased. However, in the organic EL display, there is a problem that the external light incident on the display is reflected by a reflector such as an aluminum plate provided on the back side of the display in order to increase the light extraction efficiency, thereby reducing the contrast of the image. is there. Therefore, it is known to use a circularly polarizing plate on the surface side of the display by bonding the stretched film and a polarizer in order to improve contrast of light and darkness by preventing reflection of external light. Such a circularly polarizing plate may also be used in a so-called 3D liquid crystal display device that displays a stereoscopic image.

The above circularly polarizing plate needs to be bonded so that the in-plane slow axis of the stretched film is inclined at a desired angle with respect to the absorption axis of the polarizer.

However, a general polarizer (polarizing film) is obtained by stretching at a high magnification in the transport direction, and its absorption axis coincides with the transport direction. Conventional retardation films are produced by longitudinal stretching or transverse stretching, and in principle, the in-plane slow axis is in the direction of 0 ° or 90 ° with respect to the longitudinal direction of the film. Therefore, as described above, in order to make the relationship between the absorption axis of the polarizer and the slow axis of the stretched film a desired angle that is inclined, a long polarizing film and / or a stretched film is cut out at a specific angle to obtain a film piece. There was no choice but to batch-paste them one by one, and problems such as deterioration in productivity and reduction in product yield due to adhesion of chips and the like were cited as problems. In particular, in recent years when organic EL displays are becoming larger in size, the method of cutting the obtained stretched film diagonally and pasting it on a polarizer further improves the efficiency of use of the film and decreases productivity. Was needed.

On the other hand, there is a method for producing a long retardation film that is stretched obliquely at a desired angle and whose slow axis is freely controllable in a direction that is neither 0 ° nor 90 ° with respect to the width direction of the film. Various proposals have been made (see, for example, Patent Documents 1 to 4). In these methods, the resin film is unwound from a direction different from the film winding direction after stretching, and the both ends of the resin film are gripped and transported by a pair of gripping tools while changing the transport direction. By changing the moving distance between the gripping part and the other gripping part, the resin film is stretched obliquely and has a slow axis at a desired angle of more than 0 ° and less than 90 ° with respect to the width direction. The stretched film is manufactured. By using a stretched film in which the slow axis is inclined with respect to the width direction, a long polarizing film and a stretched film are pasted by roll-to-roll instead of conventional batch-type bonding. In addition, since it becomes possible to manufacture a circularly polarizing plate, the productivity can be dramatically improved and the yield can be greatly improved.

In addition, since a circularly polarizing plate can be created by laminating with rolls, tows, and rolls, even when used in large displays, the use area of the long stretched film is increased and the manufacturing cost of the circularly polarizing plate is greatly increased. It becomes possible to reduce it.

However, when a circularly polarizing plate made using a long stretched film manufactured by the conventional oblique stretching apparatus as described above is mounted on an organic EL display, an image at the time of black display of the organic EL display is seen. In addition, a phenomenon of so-called “color unevenness” was observed, in which red or blue was applied to black and the color was different depending on the location on the display.

Further, it was found that the above phenomenon was not observed in a 3D liquid crystal display device equipped with a circularly polarizing plate, but was observed remarkably in an organic EL display equipped with a circularly polarizing plate.

As a result of examining these problems, unlike a liquid crystal display device, a self-luminous display device in which a light source corresponding to each color, such as an organic EL display, is turned on has few members such as a color filter that causes a reduction in contrast. Although the contrast is very high, it has been found that slight variations in optical characteristics are noticeably observed as color unevenness.

As a result of further examination of such a problem, in the long stretched film manufactured by the above-described conventional oblique stretching apparatus, the orientation angle varies over the width direction of the product depending on the stretching angle, and such a slight amount is caused. It was found that a large variation in orientation angle was observed as color unevenness. This problem occurs when an obliquely stretched film is produced, and does not occur with a normal transverse stretching apparatus.

As a result of research, the present inventors have found that this problem is that temperature unevenness occurs in a long film when stretching is performed in an oblique stretching apparatus that can arbitrarily change the stretching direction (stretching angle). I found out that it was caused by.

Here, the oblique stretching apparatus is installed so that a part of the gripping tool traveling support tool provided with a path along which the gripping tool travels passes through the heating furnace, thereby heating the long film to be transported obliquely. Can be stretched in the direction. As will be described in detail later, the heating furnace of the stretching apparatus is divided into a plurality of zones. The long film is heated in a heating furnace and stretched obliquely in a stretching zone.

Further, the stretching device can realize various rail patterns by changing the shape of the gripping tool traveling support provided on both sides of the traveling long film. Specifically, the shape of the gripping tool travel support tool can be changed by adjusting a drive shaft provided at the lower part in the thickness direction of the long film that normally travels. The oblique stretching apparatus is provided with a large number of drive shafts so as to cope with various stretching angles as compared with a stretching apparatus such as a normal transverse stretching.

As described above, the long film is heated in a heating furnace and stretched in a stretching zone. And generally, in a heating furnace, a long film is heated by the heater arrange | positioned up and down of the thickness direction of the long film to drive | work. However, in an oblique stretching apparatus provided with many drive shafts, it is difficult to uniformly install heaters in the lower part of the long film in the thickness direction.

That is, in the oblique stretching apparatus, there is a problem that the heater must be installed avoiding the drive shaft. FIG. 1 is a schematic diagram for explaining a heater 4 disposed in a heating furnace of a conventional oblique stretching apparatus 1. FIG. 2 is a side view of the stretching apparatus 1 of FIG. In the case of such a conventional oblique stretching apparatus 1, as shown in FIGS. 1 and 2, the heat from the heater 4 is radiated non-uniformly to the traveling long film. The gripping tool travel support tool 2 is provided with a drive shaft 3 for changing the shape of the gripping tool travel support tool 2 at predetermined intervals. When heat is radiated non-uniformly, a collision wind (not shown) is blown onto the long film. In the present specification, the impingement wind refers to a wind in which air stays due to heat radiated from the heater 4 and is blown onto a long film. In FIG. 2, the arrows indicate the position and direction of heat applied from the heater 4 to the long film F. Further, since a part of the heat dissipated discontinuously from the heater 4 arranged in a stepping stone shape is conducted to the drive shaft 3, sufficient and uniform heat is not applied to the long film F. As a result, it was found that the obtained long film F had temperature unevenness, and the variation of the orientation angle in the width direction was increased.

Further, as a method of heating the long film F at the place where the drive shaft 3 is arranged, as shown in FIGS. 3 and 4, the nozzle 4a is provided in the heater 4 arranged in a stepping stone shape, and the nozzle 4a There is a method of blowing hot air on the long film F. However, the amount of heat that can be applied to the long film F from the nozzle 4 a is smaller than the amount of heat that can be applied to the long film F from the heater 4. Therefore, in this method, heat cannot be sufficiently and uniformly applied in the transport direction of the long film F, and the temperature unevenness of the obtained long stretched film cannot be sufficiently improved.

In addition, as a method of heating the long film F at the place where the drive shaft 3 is arranged, as shown in FIGS. 5 to 7, the drive shaft 3 itself has a function as a heater. There is a method of heating the long film F by the heat radiated from. The drive shaft 3 shown in FIG. 5 has a plurality of holes 3a, and the long film F is heated by hot air blown from the holes 3a. Further, the drive shaft 3 shown in FIGS. 6 and 7 is connected to a support base 3b that supports the gripping tool travel support tool 2, and the long film F is provided with a hole (not shown) provided in the support base 3b. It is heated by hot air blown from

However, the amount of heat applied from the holes by these methods is smaller than the amount of heat that can be applied from the heater 4 to the long film F. Therefore, in this method, heat cannot be sufficiently and uniformly applied in the transport direction of the long film F, and the temperature unevenness of the obtained long stretched film cannot be sufficiently improved.

Also, the oblique stretching apparatus has a problem that when the drive shaft 3 is adjusted to change the stretching angle, the movement is hindered by the heater 4 that is installed, so that it is difficult to efficiently change the stretching angle.

Also, when a long film is conveyed at high speed, heat applied to the traveling long film is not sufficient and is not constant, and temperature unevenness is likely to occur.

Furthermore, as the film thickness of the long film is thinner, the variation in the orientation angle in the width direction due to temperature unevenness tends to increase.

JP 2008-80674 A JP 2009-78474 A JP 2010-173261 A JP 2006-159775 A

The present invention has been made in view of the above-described conventional problems. A long stretched film that can apply sufficient and constant heat to a stretched long film and has a small variation in the width direction of the orientation angle is provided. It aims at providing the manufacturing method of the elongate stretched film obtained.

As a result of studies conducted by the present inventors to achieve the above-mentioned object, in the oblique stretching apparatus, at least in the stretching zone in the heating furnace, a sheet heater is provided between the long film and the drive shaft to form a long film. It has been found that by continuously heating the film, sufficient and constant heat is applied to the stretched long film, and the above object can be achieved. Then, the inventors have further studied and have completed the present invention based on these findings.

That is, the method for producing a long stretched film according to one aspect of the present invention includes a step of forming a long film made of a thermoplastic resin, from a specific direction different from the running direction of the film after stretching the long film. The long film is fed into an oblique stretching apparatus, and the long film is obliquely stretched in a direction of greater than 0 ° and less than 90 ° with respect to the width direction while conveying the both ends of the long film with a gripping device of the oblique stretching apparatus. In the manufacturing method of the long stretched film having at least the step of winding the long stretched film after the oblique stretching step and the step of winding the long stretched film after the oblique stretching step, the oblique stretching device obliquely intersects the traveling direction of the long film before stretching. The stretching direction can be arbitrarily changed so that the traveling direction of the long stretched film after stretching is in the stretching direction, and the heating tool and the gripping tool traveling support provided on both sides of the long film are arranged. The gripping tool travel support tool includes a drive shaft below a horizontal position where the long film travels, and in the oblique stretching step, the long film is disposed in the heating furnace. At least in the stretching zone, it is continuously heated by a planar heater provided between the drive shaft and the long film.

In the present specification, the “long film” refers to a film formed before being stretched. On the other hand, the “long stretched film” refers to a film stretched through a stretching process. As will be described later, the method for producing a long film is not particularly limited, and known methods such as a coextrusion molding method, a co-casting method (solution casting method and melt casting method), a film lamination method, and a coating method. This method can be adopted. The long film obtained by these methods is stretched through an oblique stretching process to form a long stretched film.

The objects, features and advantages of the present invention will become more apparent from the following detailed description and the accompanying drawings.

FIG. 1 is a schematic view for explaining a heater arranged in a heating furnace of a conventional oblique stretching apparatus. FIG. 2 is a side view of a conventional stretching apparatus. FIG. 3 is a schematic view for explaining a heater arranged in a heating furnace of a conventional stretching apparatus. FIG. 4 is a side view of a conventional stretching apparatus. FIG. 5 is a schematic view for explaining a heater arranged in a heating furnace of a conventional stretching apparatus. FIG. 6 is a schematic view for explaining a heater arranged in a heating furnace of a conventional stretching apparatus. FIG. 7 is a side view of a conventional stretching apparatus. FIG. 8 is a schematic view for explaining an oblique stretching apparatus used in the method for producing a long stretched film according to one embodiment of the present invention. FIG. 9 is a schematic view for explaining a planar heater disposed in a heating furnace of an oblique stretching apparatus used in the manufacturing method of one embodiment of the present invention. FIG. 10 is a side view of an oblique stretching apparatus used in the manufacturing method of one embodiment of the present invention. FIG. 11 is a schematic diagram for explaining the positions of the stretching zone and the planar heater in the oblique stretching apparatus used in the manufacturing method of one embodiment of the present invention. FIG. 12 is a schematic view for explaining another example of the position of the planar heater in the oblique stretching apparatus used in the manufacturing method of one embodiment of the present invention. FIG. 13 is a schematic view of an organic EL display according to an embodiment of the present invention.

Hereinafter, although the form for implementing this invention is demonstrated in detail, this invention is not limited to these.

An embodiment of the present invention includes a step of forming a long film made of a thermoplastic resin, and the long film is transferred to a diagonal stretching device from a specific direction different from the traveling direction of the stretched film. An oblique stretching step of obliquely stretching the long film in a direction greater than 0 ° and less than 90 ° with respect to the width direction while being gripped and conveyed by a gripping tool of an oblique stretching device, and an oblique stretching step In the method for producing a long stretched film having at least a step of winding the long stretched film after, the oblique stretching apparatus has a long stretched film after being stretched in a direction oblique to the running direction of the long film before stretching. The stretching direction can be arbitrarily changed so that the traveling direction of is, and has a heating furnace and a gripping tool travel support provided on both sides of the long film, the gripping tool travel support is A drive shaft is provided below a horizontal position where the long film travels, and in the oblique stretching step, the long film is formed between the drive shaft and the long film in at least a stretching zone in the heating furnace. It is a manufacturing method of the elongate stretched film continuously heated with the planar heater provided in between.

Since the present embodiment has a feature in the oblique stretching process among the above processes, the oblique stretching process will be described in detail.

In the present specification, the long length refers to a film having a length of at least about 5 times the width of the film, preferably a length of 10 times or more, specifically in a roll shape. It has a length (film roll) that is wound and stored or transported.

Hereinafter, the present embodiment will be specifically described with reference to the drawings as appropriate.

<Method for producing long stretched film>
(Oblique stretching process)
The oblique stretching step is a step of stretching the formed long film in a direction oblique to the width direction. In the manufacturing method of a long film, a film can be manufactured to desired length by manufacturing a film continuously. In addition, after manufacturing a long film into a manufacturing method of a long stretched film, you may make it wind up to a core once and make it a wound body (it is also called an original fabric), and you may make it supply to the diagonal stretch process. Alternatively, the film after film formation may be continuously supplied to the oblique stretching process from the film forming process without winding up the film. It is preferable to perform the film forming step and the oblique stretching step continuously because the film thickness after the stretching and the result of the optical value are fed back to change the film forming conditions to obtain a desired long stretched film. .

In the method for producing a long stretched film of the present embodiment, a long stretched film having a slow axis at an angle of more than 0 ° and less than 90 ° with respect to the width direction of the film is produced. Here, the angle with respect to the width direction of the film is an angle in the film plane. Since the slow axis in the film plane is usually expressed in the stretching direction or a direction perpendicular to the stretching direction, in the production method of this embodiment, stretching is performed at an angle of more than 0 ° and less than 90 ° with respect to the film extension direction. By performing this, a long stretched film having such a slow axis can be produced.

The angle formed by the width direction of the long stretched film and the slow axis, that is, the orientation angle, can be arbitrarily set to a desired angle within a range of more than 0 ° and less than 90 °.

(Stretching with an oblique stretching device)
In order to impart an oblique orientation to the long film subjected to stretching in this embodiment, an oblique stretching apparatus is used. The oblique stretching apparatus used in the present embodiment can freely set the orientation angle of the film by changing the path pattern of the gripping tool traveling support tool in various ways, and further the orientation axis of the film across the film width direction. It is preferable that the film stretching apparatus can be oriented with high precision in the left and right directions and can control the film thickness and retardation with high precision.

FIG. 8 is a schematic diagram for explaining an oblique stretching apparatus used in the method for producing a long stretched film of the present embodiment. However, this is an example, and the present embodiment is not limited to this.

The running direction of the long film (running direction of the long film before stretching) D1 when fed into the stretching apparatus is the running direction of the long stretched film when fed from the stretching apparatus (of the long stretched film after stretching). Travel direction) is different from D2 and forms a feeding angle θi. The feeding angle θi can be arbitrarily set to a desired angle in the range of more than 0 ° and less than 90 °.

The long film has a left and right gripping tool (a pair of left and right grips) at the entrance of the oblique stretching apparatus (the gripping tool is a gripping start point for gripping the long film, and a straight line connecting the gripping start points is indicated by reference symbol A). Gripped by the gripping tool pair) and transported as the gripping tool travels.

The gripping tool pair is an entrance of the oblique stretching apparatus, and the left and right gripping tools Ci and gripping tool Co that are opposed to a direction substantially perpendicular to the running direction of the long film (the running direction D1 of the long film before stretching). Consists of. The left and right gripping tools Ci and Co travel along an asymmetrical path, respectively, and the position at the end of stretching (the gripping release point at which the gripping tool releases the gripping, and the straight line connecting the gripping release points is denoted by reference symbol B. The long stretched film gripped in (shown) is released.

At this time, the left and right gripping tools Ci and gripping tool Co, which are opposed to each other at the entrance of the oblique stretching apparatus (position A in the figure), travel on the inner gripping tool travel support tool Ri and the outer gripping tool travel support tool Ro, respectively. As a result, the gripping tool Ci traveling on the inner gripping tool travel support tool Ri is in a positional relationship that advances relative to the gripping tool Co traveling on the outer gripping tool travel support tool Ro.

That is, in the state where the gripping tool Ci and the gripping tool Co, which are opposed to the direction substantially perpendicular to the running direction D1 of the long film at the entrance of the oblique stretching apparatus, are in the position B, the gripping tool Ci and the gripping tool Co Is a positional relationship in which an angle θL is inclined from a direction substantially perpendicular to the running direction D2 of the stretched long stretched film. In the present specification, the term “substantially vertical” indicates that the angle is in the range of 90 ± 1 °. With the above operation, the long film is obliquely stretched in the direction of θL.

The manufacturing method of the present embodiment is performed using a stretching apparatus capable of oblique stretching. This stretching apparatus is an apparatus that heats a long film to an arbitrary temperature at which it can be stretched and obliquely stretches it. The stretching device includes a heating zone (heating furnace), a plurality of gripping tools that are paired on both sides for traveling on both sides of a long film, and gripping tool traveling for supporting the traveling of the gripping tool. And a support tool. Hold both ends of the long film that is sequentially supplied to the entrance (holding start point) of the stretching device with a gripper, guide the long film into the heating furnace, and hold it at the exit (holding release point) of the stretching device. Release the long stretched film from the tool. The long stretched film released from the gripping tool is wound around the core. The gripping tool traveling support tool having the gripping tool has an endless continuous track, and the gripping tool that has released the grip of the long stretched film at the exit of the stretching device is sequentially returned to the gripping start point by the gripping tool travel support tool. It is supposed to be.

For example, the endless chain whose path is regulated by a guide rail or a gear may be provided with the gripper, or the endless guide rail may be provided with the gripper. There may be. That is, in the present embodiment, the gripping tool travel support tool may be, for example, an endless guide rail provided with an endless chain, or may be an endless guide rail provided with an endless chain. It may be an endless guide rail without a chain. When the gripper travel support tool does not include a chain, the gripper travels along the path of the gripper travel support tool itself. When the gripper travel support tool includes the chain, the gripper travel support tool travels along the path of the gripper travel support tool. Run. Hereinafter, in the present embodiment, as an example, the case where the gripping tool travels along the path of the gripping tool travel support tool will be described. However, the gripping tool is routed through the chain provided with the gripping tool. You may drive.

The number of gripping tools provided in each gripping tool travel support tool is not particularly limited, but is preferably the same number.

The gripping tool travel support tool of the stretching device has an asymmetric shape on the left and right, and the pattern of the path of the gripping tool travel support tool depends on the orientation angle, stretch ratio, etc. given to the long stretched film to be manufactured. It is configured so that it can be adjusted manually or automatically. The path pattern of the gripper travel support tool is performed by adjusting the drive shaft, which will be described in detail later.

In the stretching apparatus of the present embodiment, it is preferable that the path of each gripper travel support tool can be freely set and the pattern of the path of the gripper travel support tool can be arbitrarily changed.

The length (full length) of the gripping tool travel support tool is not particularly limited, and is usually about 10 to 100 m. Moreover, the full length of the holding | gripping tool traveling support tool of both sides may be the same, and may differ.

In this embodiment, the traveling speed of the gripping tool of the stretching apparatus can be selected as appropriate, but is preferably 15 to 150 m / min. When the traveling speed of the gripping device of the stretching apparatus is higher than 150 m / min, the local stress applied to the end of the film increases at the bent portion, and wrinkles and shifts occur at the end of the film. Of the entire width of the film obtained, the effective width obtained as a non-defective product tends to narrow. In general, when the traveling speed of the gripping tool is within the above range, the long film is likely to have temperature unevenness due to insufficient heat supply. However, as will be described in detail later, the stretching apparatus used in the present embodiment is continuously provided with a planar heater at least in the stretching zone, so even when a long film is conveyed at high speed. Heat can be sufficiently and uniformly applied to the traveling long film. As a result, the variation in the width direction of the orientation angle of the obtained long film can be reduced.

The traveling speeds of the two gripping tools constituting the gripping tool pair may be the same or different. If there is a difference in travel speed between the left and right of the long stretched film at the grip release point, wrinkles and misalignment may occur in the long stretched film at the grip release point. The speed difference is preferably substantially constant.

When the traveling speeds of the gripping tools constituting the gripping tool pair are made constant, the difference between the traveling speeds of the gripping tools is preferably 1% or less, more preferably 0.5% or less, even more preferably. Is 0.1% or less. In general stretching devices, etc., there are speed irregularities that occur in the order of seconds or less depending on the period of the sprocket (gear) teeth that drive the chain, the frequency of the drive motor, etc. These do not correspond to the speed difference described in this embodiment.

The gripping tool traveling support tool that regulates the locus of the gripping tool of the oblique stretching apparatus used in the present embodiment is often required to have a high bending rate, particularly in a portion where the conveyance of the long film is slanted. In order to avoid interference between gripping tools due to sudden bending or local stress concentration, it is desirable that the trajectory of the gripping tool is curved so as to draw an arc at the bent portion.

In the present embodiment, the long film is sequentially gripped by the left and right gripping tools (a pair of gripping tools) at the entrance of the oblique stretching device (position of the straight line A in FIG. 8), and the gripping tool travels. Drive with it. The pair of gripping tools facing the direction substantially perpendicular to the long film traveling direction D1 at the entrance of the oblique stretching apparatus travels along an asymmetric path, and has a preheating zone, a stretching zone, and a heat fixing zone. Pass through.

予 Preheating zone refers to a section where the distance between the gripping tools gripping both ends is kept constant at the heating furnace entrance.

The stretching zone refers to the interval until the gap between the gripping tools that grips both ends starts to reach a predetermined interval. In the present embodiment, the film can be stretched in an oblique direction in the stretching zone. However, the stretching is not limited to the stretching in the oblique direction. You may extend | stretch in a hand direction.

The heat setting zone refers to the section in which the gripping tools at both ends run parallel to each other during the period when the spacing between the gripping tools after the stretching zone becomes constant again. You may pass through the area (cooling zone) by which the temperature in a zone is set to below the glass transition temperature Tg of the thermoplastic resin which comprises a elongate film, after passing through a heat setting zone. At this time, in consideration of shrinkage of the long stretched film due to cooling, a route pattern that narrows the gap between the opposing gripping tools in advance may be used.

In this embodiment, for the purpose of adjusting the mechanical properties and optical characteristics of the film, transverse stretching and longitudinal stretching may be performed as necessary in the steps before and after introducing the long film into the oblique stretching apparatus.

It is preferable to set the temperature of the preheating zone to Tg to Tg + 30 ° C., the temperature of the stretching zone to Tg to Tg + 30 ° C., and the temperature of the cooling zone to Tg−30 ° C. to Tg with respect to the glass transition temperature Tg of the thermoplastic resin.

Note that a temperature difference in the width direction may be applied in the stretching zone in order to control thickness unevenness in the width direction. In order to make a temperature difference in the width direction in the stretching zone, a method of adjusting the opening degree of the nozzle that sends warm air into the temperature-controlled room by making a difference in the width direction, or a method of controlling heating by arranging heaters in the width direction, etc. Techniques can be used. The length of the preheating zone, stretching zone, and heat setting zone can be appropriately selected. The length of the preheating zone is usually 100 to 150% and the length of the heat setting zone is usually 50 to 100% with respect to the length of the stretching zone. It is.

The draw ratio R (W / W0) in the drawing step is preferably 1.3 to 3.0, more preferably 1.5 to 2.8. When the draw ratio is within this range, thickness unevenness in the width direction is preferably reduced. Further, if necessary, a difference in stretching temperature in the width direction may be made in the stretching zone in order to make the thickness unevenness in the width direction even better. In addition, W0 represents the width of the long film before stretching, and W represents the width of the long stretched film after stretching.

The oblique stretching process of the manufacturing method of the present embodiment will be described more specifically with reference to FIGS. FIG. 9 is a schematic diagram for explaining the planar heater 8 disposed in the heating furnace of the oblique stretching apparatus 5 used in the present embodiment. FIG. 10 is a side view of the oblique stretching device 5. FIG. 11 is a schematic diagram for explaining the positions of the stretching zone 7 and the planar heater 8 in the oblique stretching apparatus 5.

As described above, the long film F is conveyed into the heating furnace 6 while being held by the holding tool. The heating furnace 6 is an apparatus for heating the long film F. In the manufacturing method of this embodiment, the long film F is heated from the lower side of the long film F by the planar heater 8 provided between the long film F and the drive shaft 3 at least in the stretching zone 7. . As will be described in detail later, the planar heater 8 is preferably provided throughout the heating furnace 6. While the inside of the heating furnace 6 is heated by the planar heater 8, the traveling long film F is heated.

The heating furnace 6 can be provided with a heating source other than the position where the planar heater 8 is provided. The position of the heating source is not particularly limited. At a position other than the position where the planar heater 8 is provided, the heating source can be provided on at least one of the upper and lower sides of the long film F from the viewpoint of uniformly heating the long film F. Furthermore, at the position where the planar heater 8 is provided, a heating source may be provided on the upper side in the thickness direction of the long film F, and the long film F may be heated together with the planar heater 8 from above and below. The heating method by a heat source is not specifically limited, For example, the method of spraying a hot air is employable.

As shown in FIGS. 9 and 10, the drive shaft 3 is connected to the gripping tool travel support tool 2. The drive shaft 3 is configured to be movable by a predetermined distance in a direction substantially orthogonal to the traveling direction of the long film F, and changes the shape of the gripping tool traveling support tool 2 by movement.

The method for moving the drive shaft 3 is not particularly limited. For example, as shown in FIGS. 9 and 10, a part of the gripping tool travel support tool 2 and a part of the drive shaft 3 can be connected by a connecting rod 9. In this case, by moving the drive shaft 3 in a direction substantially orthogonal to the traveling direction of the long film F, the shape of the gripping tool traveling support tool 2 can be changed via the connecting rod 9.

A gripping tool (not shown) travels along the path of the gripping tool travel support tool 2 while gripping the long film F. The long film F conveyed is heated by the planar heater 8 provided continuously on the lower surface.

As shown in FIGS. 9 and 10, the planar heater 8 is provided between the long film F and the drive shaft 3 at least in the stretching zone 7 of the heating furnace 6. The planar heater 8 can continuously and uniformly heat the traveling long film F from the lower surface, and uniformly moves the ambient air existing on the lower surface of the long film F, thereby making it difficult to generate a collision wind. be able to. Therefore, the long film F hardly causes temperature unevenness. Even when the driving shaft 3 is adjusted to change the stretching direction and the shape of the gripping tool travel support tool 2 is changed, the planar heater 8 is provided between the long film F and the driving shaft 3. Therefore, the adjustment of the drive shaft 3 is not hindered.

In the present specification, “continuously heating” refers to an operation in which the planar heater 8 uniformly applies heat to the traveling long film F as shown in FIG. 10. In FIG. 10, the heat flow continuously given is shown by the arrows arranged uniformly. That is, the heat from the heater (heater 4) arranged in a stepping stone shape shown in FIG. 2 does not continuously heat the long film F as indicated by the discontinuously arranged arrows.

The planar heater 8 of the present embodiment is not disposed between the drive shafts like the heater 4 shown in FIG. 2, but is provided between the long film F and the drive shaft 3. . For this reason, in the oblique stretching device 5 having a large number of drive shafts 3, it can be provided between the long film F and the drive shaft 3 regardless of the number and arrangement of the drive shafts 3.

The type of the planar heater 8 is not particularly limited, and a conventionally known electric heater or the like can be used. The planar heater 8 is made of, for example, a planar heater or metal foil obtained by applying or impregnating a carbon paint to a fabric woven with conductive wires and thermally fusing both sides with a heat-resistant synthetic resin sheet (for example, a polyimide sheet). A planar heater or the like integrally formed by sandwiching from both sides with a heat-resistant resin sheet can be employed. In addition, in addition to high insulation, it is excellent in high temperature and heat resistance, adopts a ceramic heater using a ceramic substrate such as alumina or aluminum nitride from the viewpoint of high temperature rise rate and long life. be able to. Furthermore, a mica heater, a quartz heater, etc. can be employed.

The shape of the planar heater 8 is not particularly limited as long as it can be provided between the long film F and the drive shaft 3. In the present embodiment, a planar heater 8 having a flat shape is employed.

The horizontal position where the planar heater 8 is provided is not particularly limited as long as it is between the long film F and the drive shaft 3. That is, the planar heater 8 can be installed on the lower surface side of the long film F with a distance that can provide sufficient and uniform heat to the long film F. Further, the planar heater 8 can be provided at a position relatively close to the long film F. Therefore, there is little heat conducted from the planar heater 8 to the drive shaft 3, and the heat from the planar heater 8 is efficiently applied to the long film F.

The method of providing the planar heater 8 is not particularly limited as long as the method is provided between the long film F and the drive shaft 3. For example, it can be connected to the gripping tool travel support tool 2 or formed integrally.

Even if the shape of the gripping tool travel support tool 2 is changed by adjusting the drive shaft 3 by connecting to the gripping tool travel support tool 2 or integrally forming the planar heater 8, The shape of the planar heater 8 can be changed following the changed shape of the gripping tool travel support tool 2. The method for changing the shape of the planar heater 8 is not particularly limited. For example, the planar heater 8 may have a slide mechanism such as a garage shutter or a ninety-nine-fold structure. May be.

The area occupied by the planar heater 8 in the width direction of the long film F is not particularly limited, as long as it is provided on the lower surface of the long film F that travels at least in the stretching zone 7, as shown in FIG. It may be provided throughout the stretching zone 7.

As shown in FIG. 11, when the planar heater 8 is provided only on the lower surface of the traveling long film F, heat is not applied to the extra space in the stretching zone 7, so the thermal efficiency of the long film F is good. On the other hand, when the planar heater 8 is provided in the entire stretching zone 7, for example, even when the stretching angle is changed and the shape of the gripping tool travel support tool 2 is changed, from the lower surface of the long film F that always travels. Heat can be applied. Moreover, it is not necessary to provide the planar heater 8 in accordance with the shape of the gripping tool travel support tool 2 after the shape is changed, and the convenience is excellent. In addition, when providing the planar heater 8 only in the lower surface of the elongate film F, when changing an extending | stretching angle, the side surface of the planar heater 8 and the connecting rod 9 may contact. Therefore, the planar heater 8 can be provided with a contact avoidance mechanism such as a long hole mechanism and a folding mechanism in advance along the movement path of the connecting rod 9. In this case, the planar heater 8 can avoid contact with the connecting rod 9 by being automatically or manually folded inside the long hole as necessary.

Further, when the planar heater 8 is provided in the entire stretching zone 7, the planar heater 8 may come into contact with the connecting rod 9 when the stretching angle is changed. Therefore, the planar heater 8 can be provided with a contact avoidance mechanism such as a long hole mechanism and a folding mechanism in advance along the movement path of the connecting rod 9. In this case, the planar heater 8 can avoid contact with the connecting rod 9 by being automatically or manually folded inside the long hole as necessary. Further, the planar heater 8 can be provided with a guide mechanism on the front and back surfaces of the planar heater 8 along the movement path of the connecting rod 9. In this case, the connecting rod 9 can be structured to be sandwiched between the planar heater 8 by an actuating member that runs on the guide mechanism from above and below.

As shown in FIG. 12, a planar heater 8 may be provided continuously throughout the heating furnace 5 including the stretching zone 7. As described above, when the planar heater 8 is continuously provided throughout the heating furnace 3, the long film F is uniformly heated even before and after the stretching zone 7 without temperature unevenness. As a result, the variation in the width direction of the orientation angle of the obtained long stretched film can be reduced regardless of the stretch angle, and a long stretched film with stable quality can be obtained.

The planar heater 8 can be provided only on the lower surface of the traveling long film F. In this case, since heat is not given to the extra space in the heating furnace 6, the thermal efficiency for the long film F is good. On the other hand, when provided throughout the heating furnace 6, for example, even when the shape of the gripping tool travel support tool 2 is changed by changing the stretching angle, heat is always applied from the lower surface of the long film F that travels. Can do. Moreover, it is not necessary to provide the planar heater 8 in accordance with the shape of the gripping tool travel support tool 2 after the shape is changed, and the convenience is excellent.

Next, other steps that can be adopted by this embodiment will be described. In addition, this embodiment should just have the above-mentioned diagonal extending process, and it does not specifically limit about other processes. For this reason, the other steps described below are examples, and the design can be changed as appropriate.

(Long film forming process)
The film forming step is a step of forming a long film made of a thermoplastic resin.

The long film formed in this embodiment is not particularly limited as long as it is a long film made of a thermoplastic resin.

For example, when using a stretched long stretched film for optical purposes, a film made of a resin transparent to a desired wavelength is preferable. Such resins include polycarbonate resins, polyether sulfone resins, polyethylene terephthalate resins, polyimide resins, polymethyl methacrylate resins, polysulfone resins, polyarylate resins, polyethylene resins, polyvinyl chloride resins. Examples thereof include resins, olefin polymer resins having an alicyclic structure, and cellulose ester resins. Among these, polycarbonate resins, olefin polymer resins having an alicyclic structure, and cellulose ester resins are preferable from the viewpoints of transparency and mechanical strength. Among them, an olefin polymer-based resin having an alicyclic structure and a cellulose ester-based resin, which are easy to adjust the phase difference in the case of an optical film, are more preferable. Therefore, even when the film is obliquely stretched by high-speed conveyance, it is particularly preferable from the viewpoint that wrinkles and shifts hardly occur at the film edge.

<Alicyclic olefin polymer resin>
Examples of the alicyclic olefin polymer-based resin include cyclic olefin random multi-component copolymers described in JP-A No. 05-310845, hydrogenated polymers described in JP-A No. 05-97978, and JP-A No. 11 The thermoplastic dicyclopentadiene ring-opening polymer and hydrogenated product thereof described in JP-A-124429 can be employed.

The olefin polymer resin having an alicyclic structure will be described more specifically. The alicyclic olefin polymer-based resin is a polymer having an alicyclic structure such as a saturated alicyclic hydrocarbon (cycloalkane) structure or an unsaturated alicyclic hydrocarbon (cycloalkene) structure. The number of carbon atoms constituting the alicyclic structure is not particularly limited, but is usually 4 to 30, preferably 5 to 20, more preferably 5 to 15, and the mechanical strength, heat resistance and The formability characteristics of the long film are highly balanced and suitable.

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

Examples of the olefin polymer resin having an alicyclic structure include norbornene resins, monocyclic olefin resins, cyclic conjugated diene resins, vinyl alicyclic hydrocarbon resins, and hydrides thereof. Among these, norbornene-based resins can be suitably used because of their good transparency and moldability. In addition, since a long stretched film obtained using a norbornene-based resin has low stretching stress, the occurrence of wrinkles and shifts at the end of the long stretched film is reduced even when transported at high speed, and the orientation angle is reduced. Variation in the longitudinal direction can be suppressed.

Examples of the norbornene-based resin include a ring-opening polymer of a monomer having a norbornene structure, a ring-opening copolymer of a monomer having a norbornene structure and another monomer, a hydride thereof, and a norbornene structure. And an addition copolymer of a monomer having a norbornene structure and an addition copolymer of another monomer or a hydride thereof. Among these, a ring-opening (co) polymer hydride of a monomer having a norbornene structure is particularly suitable from the viewpoints of transparency, moldability, heat resistance, low hygroscopicity, dimensional stability and lightness. Can be used.

Examples of the monomer having a norbornene structure include bicyclo [2.2.1] hept-2-ene (common name: norbornene), tricyclo [4.3.0.12,5] deca-3,7-diene ( Common name: dicyclopentadiene), 7,8-benzotricyclo [4.3.12,5] dec-3-ene (common name: methanotetrahydrofluorene), tetracyclo [4.4.0.12, 5.17,10] dodec-3-ene (common name: tetracyclododecene), and derivatives of these compounds (for example, those having a substituent in the ring). Here, examples of the substituent include an alkyl group, an alkylene group, and a polar group. Moreover, these substituents may be the same or different and a plurality may be bonded to the ring. Monomers having a norbornene structure can be used singly or in combination of two or more.

Examples of the polar group include heteroatoms or atomic groups having heteroatoms. Examples of the hetero atom include an oxygen atom, a nitrogen atom, a sulfur atom, a silicon atom, and a halogen atom. Specific examples of the polar group include a carboxyl group, a carbonyloxycarbonyl group, an epoxy group, a hydroxy group, an oxy group, an ester group, a silanol group, a silyl group, an amino group, a nitrile group, and a sulfo group.

Other monomers capable of ring-opening copolymerization with monomers having a norbornene structure include monocyclic olefins such as cyclohexene, cycloheptene and cyclooctene and derivatives thereof; and cyclic conjugated dienes such as cyclohexadiene and cycloheptadiene. And derivatives thereof;

A ring-opening polymer of a monomer having a norbornene structure and a ring-opening copolymer of a monomer having a norbornene structure and another monomer copolymerizable with the monomer have a known ring-opening polymerization catalyst. It can be obtained by (co) polymerization in the presence.

Other monomers that can be copolymerized with a monomer having a norbornene structure include, for example, α-olefins having 2 to 20 carbon atoms such as ethylene, propylene, and 1-butene, and derivatives thereof; cyclobutene, cyclopentene, and And cycloolefins such as cyclohexene and derivatives thereof; and non-conjugated dienes such as 1,4-hexadiene, 4-methyl-1,4-hexadiene and 5-methyl-1,4-hexadiene. These monomers can be used alone or in combination of two or more. Among these, α-olefin is preferable, and ethylene is more preferable.

An addition polymer of a monomer having a norbornene structure and an addition copolymer of a monomer having a norbornene structure with another monomer copolymerizable with a monomer having a norbornene structure are prepared in the presence of a known addition polymerization catalyst. It can be obtained by polymerization.

A hydrogenated product of a ring-opening polymer of a monomer having a norbornene structure, a hydrogenated product of a ring-opening copolymer of a monomer having a norbornene structure and another monomer capable of ring-opening copolymerization thereof, Hydrogenated products of addition polymers of monomers having a norbornene structure, and hydrogenated products of addition copolymers of monomers having a norbornene structure and other monomers copolymerizable therewith It can be obtained by adding a known hydrogenation catalyst containing a transition metal such as nickel or palladium to the polymer solution and hydrogenating carbon-carbon unsaturated bonds, preferably 90% or more.

Among norbornene-based resins, as a repeating unit, X: bicyclo [3.3.0] octane-2,4-diyl-ethylene structure and Y: tricyclo [4.3.0.12,5] decane-7, Having a 9-diyl-ethylene structure, the content of these repeating units is 90% by weight or more based on the total repeating units of the norbornene resin, and the X content ratio and the Y content ratio The ratio is preferably 100: 0 to 40:60 by weight ratio of X: Y. By using such a resin, the optical material obtained by the long stretched film of the present embodiment can be made long-term without dimensional change and excellent in optical properties.

The molecular weight of the norbornene-based resin is appropriately selected depending on the purpose of use, but is converted to polyisoprene measured by gel permeation chromatography using cyclohexane (toluene if the thermoplastic resin does not dissolve) as the solvent (the solvent is In the case of toluene, the weight average molecular weight (Mw) in terms of polystyrene is usually 10,000 to 100,000, preferably 15,000 to 80,000, more preferably 20,000 to 50,000. When the weight average molecular weight is in such a range, the mechanical strength and molding processability of the optical material obtained by the long stretched film of this embodiment are highly balanced and suitable.

The glass transition temperature of the norbornene-based resin may be appropriately selected depending on the purpose of use, but is preferably 80 ° C. or higher, more preferably in the range of 100 to 250 ° C. When the glass transition temperature is in such a range, the optical material obtained by the long stretched film of the present embodiment can be made excellent in durability without causing deformation or stress in use at high temperatures. it can.

The molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) of the norbornene resin is not particularly limited, but is usually 1.0 to 10.0, preferably 1.1 to 4.0, more preferably 1 The range is from 2 to 3.5.

The absolute value of the photoelastic coefficient C of norbornene-based resin is preferably ¹⁰ × 10 -12 ^{Pa -1} or less, more preferably 7 × ¹⁰ -12 ^{Pa -1} or less, 4 × ¹⁰ -12 Pa Particularly preferably, it is ⁻¹ or less. The photoelastic coefficient C is a value expressed by Δn / σ where birefringence is Δn and stress is σ. When the photoelastic coefficient of the thermoplastic resin is within such a range, variation in retardation (Re) in the in-plane direction, which will be described later, can be reduced.

The thermoplastic resin used in this embodiment is a colorant such as a pigment or dye, a fluorescent brightener, a dispersant, a heat stabilizer, a light stabilizer, an ultraviolet absorber, an antistatic agent, an antioxidant, a lubricant, a solvent, and the like. These compounding agents may be appropriately blended.

The content of the residual volatile component in the long stretched film using the norbornene resin is not particularly limited, but is preferably 0.1% by mass or less, more preferably 0.05% by mass or less, and further preferably 0.02%. It is below mass%. By making the content of the volatile component in such a range, the dimensional stability can be improved, the change with time of Re can be reduced, and further the retardation obtained from the long stretched film of the present embodiment. Deterioration of an image display device such as a film, a polarizing plate or an organic EL display can be suppressed, and the display of the image display device such as an organic EL display can be kept stable and favorable for a long time. The residual volatile component is a substance having a molecular weight of 200 or less contained in a small amount in the long film, and examples thereof include a residual monomer and a solvent. The content of the residual volatile component can be quantified by analyzing the long film by gas chromatography as the total of substances having a molecular weight of 200 or less contained in the long film.

The saturated water absorption of the long stretched film using norbornene-based resin is preferably 0.03% by mass or less, more preferably 0.02% by mass or less, and particularly preferably 0.01% by mass or less. When the saturated water absorption is in the above range, the change with time of Re can be reduced, and further, the retardation film obtained from the long stretched film of the present embodiment, a polarizing plate, or an image display device such as an organic EL display can be used. Deterioration can be suppressed, and display on an image display device such as an organic EL display can be stably and satisfactorily maintained over a long period.

Saturated water absorption is a value expressed as a percentage of the mass of a test piece of a long film immersed in water at a constant temperature for a fixed time and the increased mass before the immersion. Usually, it is measured by immersing in 23 ° C. water for 24 hours. The saturated water absorption rate in the long stretched film of the present embodiment can be adjusted to the above value, for example, by reducing the amount of polar groups in the thermoplastic resin. In order to adjust the saturated water absorption rate to the above value, in this embodiment, it is preferable to use a norbornene-based resin having no polar group.

As a method for forming a long film using the above preferred norbornene-based resin, a solution casting method or a melt extrusion method is preferred. Examples of the melt extrusion method include an inflation method using a die, but a method using a T die is preferable in terms of excellent productivity and thickness accuracy.

In the melt extrusion method using a T-die, as described in JP-A-2004-233604, a method of maintaining retardation and orientation angle by a method of keeping a molten thermoplastic resin in a stable state when closely contacting a cooling drum. Thus, it is possible to produce a long film with good optical property variation.

Specifically, 1) When producing a long film by the melt extrusion method, a sheet-like thermoplastic resin extruded from a die is brought into close contact with a cooling drum under a pressure of 50 kPa or less; 2) melting When producing a long film by extrusion, the enclosure member covers from the die opening to the first cooling drum that is in close contact, and the distance from the enclosure member to the die opening or the first contact cooling drum is 100 mm or less. Method: 3) Method of heating the temperature of the atmosphere within 10 mm to a specific temperature from the sheet-like thermoplastic resin extruded from the die opening when producing a long film by the melt extrusion method; A sheet-like thermoplastic resin extruded from a die so as to satisfy the above condition is taken into close contact with a cooling drum under a pressure of 50 kPa or less; A method in which a wind having a speed difference of 0.2 m / s or less from the cooling speed of the cooling drum that is first brought into close contact with the sheet-like thermoplastic resin extruded from the die opening is produced. It is done.

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

<Cellulose ester resin>
Examples of the cellulose ester-based resin include those characterized by containing a cellulose acylate satisfying the following formulas (i) and (ii) and containing a compound represented by the following general formula (A). .

Formula (i) 2.0 ≦ Z1 <3.0
Formula (ii) 0 ≦ X <3.0
(In Formula (i) and Formula (ii), Z1 represents the total acyl substitution degree of cellulose acylate, and X represents the sum of the propionyl substitution degree and butyryl substitution degree of cellulose acylate)

(Compound of general formula (A))
Hereinafter, the compound of the general formula (A) will be described in detail.

In the general formula (A), L ₁ and L ₂ each independently represent a single bond or a divalent linking group.

Examples of L ₁ and L ₂ include the following structures. (R below represents a hydrogen atom or a substituent)

L ₁ and L ₂ are preferably —O—, —COO—, and —OCO—. R ₁ , R ₂ and R ₃ each independently represent a substituent.

Specific examples of the substituent represented by R ₁ , R ₂ and R ₃ include a halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom, etc.), alkyl group (methyl group, ethyl group, n-propyl group, Isopropyl group, tert-butyl group, n-octyl group, 2-ethylhexyl group, etc.), cycloalkyl group (cyclohexyl group, cyclopentyl group, 4-n-dodecylcyclohexyl group, etc.), alkenyl group (vinyl group, allyl group, etc.) , Cycloalkenyl groups (2-cyclopenten-1-yl, 2-cyclohexen-1-yl group, etc.), alkynyl groups (ethynyl group, propargyl group, etc.), aryl groups (phenyl group, p-tolyl group, naphthyl group, etc.) Heterocyclic group (2-furyl group, 2-thienyl group, 2-pyrimidinyl group, 2-benzothiazolyl group, etc.), cyano group, hydride Roxyl group, nitro group, carboxyl group, alkoxy group (methoxy group, ethoxy group, isopropoxy group, tert-butoxy group, n-octyloxy group, 2-methoxyethoxy group, etc.), aryloxy group (phenoxy group, 2- Methylphenoxy group, 4-tert-butylphenoxy group, 3-nitrophenoxy group, 2-tetradecanoylaminophenoxy group, etc.), acyloxy group (formyloxy group, acetyloxy group, pivaloyloxy group, stearoyloxy group, benzoyloxy group) , P-methoxyphenylcarbonyloxy group, etc.), amino group (amino group, methylamino group, dimethylamino group, anilino group, N-methyl-anilino group, diphenylamino group, etc.), acylamino group (formylamino group, acetylamino group) Group, pivaloylamino group Lauroylamino group, benzoylamino group, etc.), alkyl and arylsulfonylamino groups (methylsulfonylamino group, butylsulfonylamino group, phenylsulfonylamino group, 2,3,5-trichlorophenylsulfonylamino group, p-methylphenylsulfonylamino group) Group), mercapto group, alkylthio group (methylthio group, ethylthio group, n-hexadecylthio group, etc.), arylthio group (phenylthio group, p-chlorophenylthio group, m-methoxyphenylthio group, etc.), sulfamoyl group (N-ethyl). Sulfamoyl group, N- (3-dodecyloxypropyl) sulfamoyl group, N, N-dimethylsulfamoyl group, N-acetylsulfamoyl group, N-benzoylsulfamoyl group, N- (N′phenylcarbamoyl) ) Sulf Moyl group, etc.), sulfo group, acyl group (acetyl group, pivaloylbenzoyl group, etc.), carbamoyl group (carbamoyl group, N-methylcarbamoyl group, N, N-dimethylcarbamoyl group, N, N-di-n-) Octylcarbamoyl group, N- (methylsulfonyl) carbamoyl group and the like.

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

R ₃ is preferably a hydrogen atom, halogen atom, alkyl group, alkenyl group, aryl group, heterocyclic group, hydroxyl group, carboxyl group, alkoxy group, aryloxy group, acyloxy group, cyano group, amino group, More preferably, they are a hydrogen atom, a halogen atom, an alkyl group, a cyano group, and an alkoxy group.

Wa and Wb represent a hydrogen atom or a substituent,
(I) Wa and Wb may be bonded to each other to form a ring;
(II) At least one of Wa and Wb may have a ring structure, or (III) At least one of Wa and Wb may be an alkenyl group or an alkynyl group.

Specific examples of the substituent represented by Wa and Wb include halogen atoms (fluorine atom, chlorine atom, bromine atom, iodine atom, etc.), alkyl groups (methyl group, ethyl group, n-propyl group, isopropyl group, tert- Butyl group, n-octyl group, 2-ethylhexyl group, etc.), cycloalkyl group (cyclohexyl group, cyclopentyl group, 4-n-dodecylcyclohexyl group, etc.), alkenyl group (vinyl group, allyl group, etc.), cycloalkenyl group ( 2-cyclopenten-1-yl, 2-cyclohexen-1-yl group, etc.), alkynyl group (ethynyl group, propargyl group etc.), aryl group (phenyl group, p-tolyl group, naphthyl group etc.), heterocyclic group ( 2-furyl group, 2-thienyl group, 2-pyrimidinyl group, 2-benzothiazolyl group, etc.), cyano group, hydroxy Group, nitro group, carboxyl group, alkoxy group (methoxy group, ethoxy group, isopropoxy group, tert-butoxy group, n-octyloxy group, 2-methoxyethoxy group, etc.), aryloxy group (phenoxy group, 2-methyl group) Phenoxy group, 4-tert-butylphenoxy group, 3-nitrophenoxy group, 2-tetradecanoylaminophenoxy group, etc.), acyloxy group (formyloxy group, acetyloxy group, pivaloyloxy group, stearoyloxy group, benzoyloxy group, p-methoxyphenylcarbonyloxy group, etc.), amino group (amino group, methylamino group, dimethylamino group, anilino group, N-methyl-anilino group, diphenylamino group, etc.), acylamino group (formylamino group, acetylamino group) , Pivaloylamino group, laur Ylamino group, benzoylamino group, etc.), alkyl and arylsulfonylamino groups (methylsulfonylamino group, butylsulfonylamino group, phenylsulfonylamino group, 2,3,5-trichlorophenylsulfonylamino group, p-methylphenylsulfonylamino group) Etc.), mercapto group, alkylthio group (methylthio group, ethylthio group, n-hexadecylthio group, etc.), arylthio group (phenylthio group, p-chlorophenylthio group, m-methoxyphenylthio group, etc.), sulfamoyl group (N-ethylsulfide group, etc.) Famoyl group, N- (3-dodecyloxypropyl) sulfamoyl group, N, N-dimethylsulfamoyl group, N-acetylsulfamoyl group, N-benzoylsulfamoyl group, N- (N'phenylcarbamoyl) Sulfamoy Group), sulfo group, acyl group (acetyl group, pivaloylbenzoyl group, etc.), carbamoyl group (carbamoyl group, N-methylcarbamoyl group, N, N-dimethylcarbamoyl group, N, N-di-n-) Octylcarbamoyl group, N- (methylsulfonyl) carbamoyl group and the like.

The above substituent may be further substituted with the above substituent.

(1) When Wa and Wb are bonded to each other to form a ring, the following structures may be mentioned.

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

In the general formula (1), A ₁ and A ₂ each independently represent —O—, —S—, —NRx— (Rx represents a hydrogen atom or a substituent) or CO—. The example of the substituent represented by Rx is synonymous with the specific example of the substituent represented by said Wa and Wb. Rx is preferably a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group. In the general formula (1), X represents a nonmetallic atom belonging to Groups 14-16. X is preferably ═O, ═S, ═NRc, ═C (Rd) Re. Here, Rc, Rd, and Re represent substituents, and examples thereof are synonymous with specific examples of the substituents represented by Wa and Wb. _{_{_{_{L 1, L 2, R 1}}}} , R _{2, R} 3, n is _{_{_{_{L 1, L 2, R 1}}}} , same meanings as R _{2, R} 3, n in the general formula (A).

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

Y represents a substituent. As an example of the substituent represented by Y, it is synonymous with the specific example of the substituent represented by said Wa and Wb. Y is preferably an aryl group, a heterocyclic group, an alkenyl group, or an alkynyl group. Examples of the aryl group represented by Y include a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, and a biphenyl group. A phenyl group and a naphthyl group are preferable, and a phenyl group is more preferable.

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

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

_{_{_{_{L 1, L 2, R 1}}}} , R _{2, R} 3, n is _{_{_{_{L 1, L 2, R 1}}}} , same meanings as R _{2, R} 3, n in the general formula (A).

(2) In the general formula (A), a specific example when at least one of Wa and Wb has a ring structure is preferably the following general formula (3).

In the general formula (3), Q ₃ represents ═N— or ═CRz— (Rz represents a hydrogen atom or a substituent), and Q ₄ represents a nonmetallic atom belonging to Groups 14-16. Z represents a nonmetallic atom group forming a ring together with Q ₃ and Q ₄ . The ring formed from Q ₃ , Q ₄ and Z may be further condensed with another ring. The ring formed from Q ₃ , Q ₄ and Z is preferably a nitrogen-containing 5-membered ring or 6-membered ring condensed with a benzene ring. _{_{_{_{L 1, L 2, R 1}}}} , R _{2, R} 3, n is _{_{_{_{L 1, L 2, R 1}}}} , same meanings as R _{2, R} 3, n in the general formula (A).

(3) When at least one of Wa and Wb is an alkenyl group or an alkynyl group, a preferred alkenyl group or alkynyl group is a vinyl group or ethynyl group having a substituent.

Among the compounds represented by the above general formula (1), general formula (2), and general formula (3), the compound represented by general formula (3) is particularly preferable.

The compound represented by the general formula (3) is superior in heat resistance and light resistance to the compound represented by the general formula (1), and is an organic solvent compared to the compound represented by the general formula (2). The solubility with respect to and the compatibility with a polymer are favorable.

The compound represented by the general formula (A) can be contained by appropriately adjusting the amount for imparting desired wavelength dispersibility and anti-bleeding property. The content is preferably 1 to 15% by mass, and particularly preferably 2 to 10% by mass. If it is in this range, sufficient wavelength dispersibility and bleeding prevention property can be imparted to the cellulose derivative.

In addition, the compounds represented by the general formula (A), the general formula (1), the general formula (2), and the general formula (3) can be synthesized with reference to known methods. Specifically, it can be synthesized with reference to Journal of Chemical Crystallography (1997); 27 (9); 512-526), JP2010-31223, JP2008-107767, and the like.

(Cellulose acylate)
The cellulose acylate film that can be used in the present embodiment contains cellulose acylate as a main component.

The cellulose acylate film preferably contains cellulose acylate in the range of 60 to 100% by mass with respect to 100% by mass of the total mass of the film. Further, the total acyl group substitution degree of cellulose acylate is 2.0 or more and less than 3.0, and more preferably 2.2 to 2.7.

Examples of the cellulose acylate include esters of cellulose and aliphatic carboxylic acids and / or aromatic carboxylic acids having about 2 to 22 carbon atoms, and in particular, esters of cellulose and lower fatty acids having 6 or less carbon atoms. Preferably there is.

The acyl group bonded to the hydroxyl group of cellulose may be linear or branched, and may form a ring. Furthermore, another substituent may be substituted. When the degree of substitution is the same, birefringence decreases when the number of carbon atoms described above is large. Therefore, the number of carbon atoms is preferably selected from acyl groups having 2 to 6 carbon atoms. The degree of propionyl substitution and the degree of butyryl substitution are preferred. Is a sum of 0 or more and less than 3.0. The cellulose acylate preferably has 2 to 4 carbon atoms, more preferably 2 to 3 carbon atoms.

Specifically, cellulose acylate includes propionate group, butyrate group or phthalyl group in addition to acetyl group such as cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate propionate butyrate or cellulose acetate phthalate. Bound cellulose mixed fatty acid esters can be used. The butyryl group forming butyrate may be linear or branched.

As the cellulose acylate, cellulose acetate, cellulose acetate butyrate, or cellulose acetate propionate is particularly preferably used.

Further, as the cellulose acylate, those that simultaneously satisfy the following formula (iii) and formula (iv) are preferable.

Formula (iii) 2.0 ≦ X + Y <3.0
Formula (iv) 0 ≦ X <3.0
In the formula, Y represents the degree of substitution of the acetyl group, and X represents the degree of substitution of the propionyl group or butyryl group or a mixture thereof.

Also, in order to obtain optical properties that meet the purpose, resins having different degrees of substitution may be mixed and used. In this case, the mixing ratio is preferably 1:99 to 99: 1 (mass ratio).

Among the above, cellulose acetate propionate is particularly preferably used as the cellulose acylate. In cellulose acetate propionate, 0 ≦ Y ≦ 2.5 and 0.5 ≦ X <3.0 are preferable (where 2.0 ≦ X + Y <3.0), More preferably, 0.5 ≦ Y ≦ 2.0 and 1.0 ≦ X ≦ 2.0 (where 2.0 ≦ X + Y <3.0). The substitution degree of the acyl group can be measured according to ASTM-D817-96.

The number average molecular weight of the cellulose acylate is preferably in the range of 60000 to 300000, since the mechanical strength of the obtained long stretched film becomes strong. More preferably, cellulose acylate having a number average molecular weight of 70,000 to 200,000 is used.

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

Solvent: methylene chloride;
Column: Three Shodex K806, K805, K803G (manufactured by Showa Denko KK) are connected and used;
Column temperature: 25 ° C .;
Sample concentration: 0.1% by mass;
Detector: RI Model 504 (manufactured by GL Sciences);
Pump: L6000 (manufactured by Hitachi, Ltd.);
Flow rate: 1.0 ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corp.) Mw = 1000,000 to 500, using a calibration curve with 13 samples. Thirteen samples are used at approximately equal intervals.

The residual sulfuric acid content in the cellulose acylate is preferably in the range of 0.1 to 45 mass ppm in terms of elemental sulfur. These are considered to be contained in the form of salts. If the residual sulfuric acid content exceeds 45 ppm by mass, the long film tends to break during hot stretching or slitting after hot stretching. The residual sulfuric acid content is more preferably in the range of 1 to 30 ppm by mass. The residual sulfuric acid content can be measured by the method prescribed in ASTM D817-96.

In addition, the free acid content in the cellulose acylate is preferably 1 to 500 ppm by mass. When it is in the above range, the long film is hardly broken as described above. The free acid content is preferably in the range of 1 to 100 ppm by mass, and the long film is more difficult to break. In particular, the range of 1 to 70 ppm by mass is preferable. The free acid content can be measured by the method prescribed in ASTM D817-96.

By washing the synthesized cellulose acylate more sufficiently than when used in the solution casting method, the residual alkaline earth metal content, residual sulfuric acid content, and residual acid content are within the above ranges. And can be preferable.

Moreover, it is preferable that a cellulose acylate is a thing with few bright spot foreign materials when it is set as a elongate stretched film. Bright spot foreign matter means that when two polarizing plates are placed in a crossed Nicol state, an optical film or the like is placed between them, light is applied from one polarizing plate side, and observation is performed from the other polarizing plate side. It means a point (foreign matter) where light from the opposite side appears to leak. The number of bright spots having a diameter of 0.01 mm or more is preferably 200 / cm ² or less, more preferably 100 / cm ² or less, and 50 / cm ² or less. Is more preferably 30 pieces / cm ² or less, particularly preferably 10 pieces / cm ² or less, and most preferably none.

Further, the bright spot having a diameter of 0.005 to 0.01 mm is also preferably 200 pieces / cm ² or less, more preferably 100 pieces / cm ² or less, and 50 pieces / cm ² or less. Is more preferably 30 pieces / cm ² or less, particularly preferably 10 pieces / cm ² or less, and most preferably none.

There are no particular limitations on cellulose as a raw material for cellulose acylate, but examples include cotton linters, wood pulp, and kenaf. Moreover, the cellulose acylate obtained from them can be mixed and used at an arbitrary ratio.

Cellulose acylate can be produced by a known method. Specifically, for example, it can be synthesized with reference to the method described in JP-A-10-45804.

In addition, cellulose acylate is also affected by trace metal components in cellulose acylate. These trace metal components are thought to be related to the water used in the production process, but it is preferable that there are few components that can become insoluble nuclei, in particular, metal ions such as iron, calcium, magnesium, An insoluble matter may be formed by salt formation with a polymer degradation product or the like that may contain an organic acidic group, and it is preferable that the amount is small. In addition, the calcium (Ca) component easily forms a coordination compound (that is, a complex) with an acidic component such as a carboxylic acid or a sulfonic acid, and many ligands. Insoluble starch, turbidity) may be formed, so it is preferable that the amount be small.

Specifically, for the iron (Fe) component, the content in cellulose acylate is preferably 1 mass ppm or less. As for the calcium (Ca) component, the content in the cellulose acylate is preferably 60 ppm by mass or less, more preferably 0 to 30 ppm by mass. Further, regarding the magnesium (Mg) component, if it is too much, an insoluble matter is generated. Therefore, the content in the cellulose acylate is preferably 0 to 70 ppm by mass, and particularly preferably 0 to 20 ppm by mass.

It should be noted that the content of metal components such as the content of iron (Fe) component, the content of calcium (Ca) component, the content of magnesium (Mg) component, etc., is a micro digest wet cracking device ( After pretreatment with sulfuric acid decomposition (sulfuric acid decomposition) and alkali melting, analysis can be performed using ICP-AES (Inductively Coupled Plasma Atomic Emission Spectrometer).

(Additive)
The long stretched film obtained by the present embodiment may be obtained by appropriately mixing polymer components other than the cellulose ester described later. The polymer component to be mixed is preferably one having excellent compatibility with the cellulose ester, and the transmittance when formed into a long stretched film is 80% or more, more preferably 90% or more, and further preferably 92% or more. preferable.

Additives that can be added include plasticizers, UV absorbers, retardation modifiers, antioxidants, deterioration inhibitors, peeling aids, surfactants, dyes, and fine particles. In the present embodiment, additives other than the fine particles may be added during the preparation of the cellulose ester solution, or may be added during the preparation of the fine particle dispersion. It is preferable to add a plasticizer, an antioxidant, an ultraviolet absorber, or the like that imparts heat and moisture resistance to a polarizing plate used in an image display device such as an organic EL display.

These compounds are preferably contained in an amount of 1 to 30% by mass, preferably 1 to 20% by mass, based on the cellulose ester. In order to suppress bleeding out during stretching and drying, a compound having a vapor pressure at 200 ° C. of 1400 Pa or less is preferable.

These compounds may be added together with the cellulose ester and the solvent during the preparation of the cellulose ester solution, or may be added during or after the solution preparation.

(Retardation adjuster)
As a compound to be added for adjusting retardation, an aromatic compound having two or more aromatic rings as described in the specification of European Patent 911,656A2 can be used.

Two or more aromatic compounds may be used in combination. The aromatic ring of the aromatic compound includes an aromatic heterocyclic ring in addition to the aromatic hydrocarbon ring. Particularly preferred is an aromatic heterocycle, and the aromatic heterocycle is generally an unsaturated heterocycle. Of these, a 1,3,5-triazine ring is particularly preferred.

(Polymer or oligomer)
The cellulose ester film in the present embodiment has a cellulose ester and a substituent selected from a carboxyl group, a hydroxyl group, an amino group, an amide group, and a sulfo group, and has a weight average molecular weight in the range of 500 to 200,000. It is preferable to contain a polymer or oligomer of a certain vinyl compound. The mass ratio of the content of the cellulose ester and the polymer or oligomer is preferably in the range of 95: 5 to 50:50.

(Matting agent)
In the present embodiment, fine particles can be contained in the long stretched film as a matting agent, whereby when the stretched film is long, conveyance and winding can be facilitated.

The particle size of the matting agent is preferably 10 nm to 0.1 μm primary particles or secondary particles. A substantially spherical matting agent having a primary particle acicular ratio of 1.1 or less is preferably used.

As the fine particles, those containing silicon are preferable, and silicon dioxide is particularly preferable. Preferred fine particles of silicon dioxide include those commercially available under the trade names of Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (manufactured by Nippon Aerosil Co., Ltd.). Aerosil 200V, R972, R972V, R974, R202, R812 can be preferably used. Examples of polymer fine particles include silicone resin, fluororesin and acrylic resin. The polymer fine particles are preferably silicone resins, particularly those having a three-dimensional network structure. For example, Tospearl 103, 105, 108, 120, 145, 3120 and 240 (Toshiba Silicone Corporation ) Made).

The silicon dioxide fine particles preferably have a primary average particle diameter of 20 nm or less and an apparent specific gravity of 70 g / L or more. The average primary particle diameter is more preferably 5 to 16 nm, and further preferably 5 to 12 nm. A smaller primary particle average diameter is preferred because haze is low. The apparent specific gravity is preferably 90 to 200 g / L or more, and more preferably 100 to 200 g / L or more. Higher apparent specific gravity makes it possible to produce a high-concentration fine particle dispersion, which is preferable because no haze or aggregates are generated.

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

(Other additives)
In addition, thermal stabilizers such as inorganic fine particles such as kaolin, talc, diatomaceous earth, quartz, calcium carbonate, barium sulfate, titanium oxide, and alumina, and salts of alkaline earth metals such as calcium and magnesium may be added. Further, a surfactant, a peeling accelerator, an antistatic agent, a flame retardant, a lubricant, an oil agent and the like may be added.

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

<Polycarbonate resin>
Next, the polycarbonate resin will be described.

As the polycarbonate-based resin, various resins can be used without particular limitation, and aromatic polycarbonate-based resins are preferable from the viewpoint of chemical properties and physical properties, and bisphenol A-based polycarbonate resins are particularly preferable. Among these, those using a bisphenol A derivative in which a benzene ring, a cyclohexane ring, an aliphatic hydrocarbon group and the like are introduced into bisphenol A are more preferable. Furthermore, a polycarbonate resin obtained by using a derivative in which the above functional group is introduced asymmetrically with respect to the central carbon of bisphenol A and having a structure in which the anisotropy in the unit molecule is reduced is particularly preferable. Examples of such polycarbonate resins include those in which two methyl groups in the center carbon of bisphenol A are replaced with benzene rings, and one hydrogen in each benzene ring of bisphenol A is replaced by a methyl group or a phenyl group. A polycarbonate resin obtained by using an asymmetric substitution with respect to the central carbon is particularly preferred. Specifically, 4,4′-dihydroxydiphenylalkane or a halogen-substituted product thereof can be obtained by a phosgene method or a transesterification method. For example, 4,4′-dihydroxydiphenylmethane, 4,4′-dihydroxydiphenyl Examples include ethane and 4,4'-dihydroxydiphenylbutane. Other examples include polycarbonate resins described in JP-A-2006-215465, JP-A-2006-91836, JP-A-2005-121813, JP-A-2003-167121, and the like.

The polycarbonate resin may be used by mixing with a transparent resin such as polystyrene resin, methyl methacrylate resin, and cellulose acetate resin. Moreover, you may laminate | stack the resin layer containing a polycarbonate-type resin on the at least one surface of the resin film formed using the cellulose acetate type resin.

The polycarbonate resin preferably has a glass transition point (Tg) of 110 ° C. or higher and a water absorption rate (measured under conditions of 23 ° C. water and 24 hours) of 0.3% or less. Moreover, Tg is 120 degreeC or more, and a water absorption rate is 0.2% or less more preferable.

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

Next, a method for forming a thermoplastic resin film will be described. In the following description, a method of forming a long film of cellulose ester resin will be described as an example.

<Solution casting method>
The solution casting method is preferable from the viewpoints of suppression of film coloring, suppression of foreign matter defects, suppression of optical defects such as die lines, excellent film flatness, and transparency.

(Organic solvent)
An organic solvent useful for forming a dope for producing a cellulose ester resin film by a solution casting method can be used without limitation as long as it dissolves cellulose acetate and other additives simultaneously.

For example, as a chlorine organic solvent, methylene chloride, as a non-chlorine organic solvent, methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, cyclohexanone, ethyl formate, 2,2,2-trifluoroethanol, 2,2,3,3-hexafluoro-1-propanol, 1,3-difluoro-2-propanol, 1,1,1,3,3,3-hexafluoro- 2-methyl-2-propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3,3-pentafluoro-1-propanol, nitroethane, etc. Methylene chloride, methyl acetate, ethyl acetate and acetone can be preferably used.

In addition to the organic solvent, the dope preferably contains 1 to 40% by mass of a linear or branched aliphatic alcohol having 1 to 4 carbon atoms. When the proportion of alcohol in the dope increases, the web gels and becomes easy to peel off from the metal support. When the proportion of alcohol is small, the role of promoting cellulose acetate dissolution in non-chlorine organic solvent systems There is also.

In particular, in a solvent containing methylene chloride and a linear or branched aliphatic alcohol having 1 to 4 carbon atoms, at least 15 to 45 mass in total of at least three kinds of acrylic resin, cellulose ester resin, and acrylic particles are used. It is preferable that the dope composition is dissolved in%.

Examples of the linear or branched aliphatic alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, and tert-butanol. Among these, ethanol is preferable because of stability of the dope, relatively low boiling point, and good drying properties.

(Solution casting method)
In the solution casting method, a step of preparing a dope by dissolving a resin and an additive in a solvent, a step of casting the dope on a belt-like or drum-like metal support, and a step of drying the cast dope as a web , A step of peeling from the metal support, a step of stretching or maintaining the width, a step of drying, and a step of winding up the finished long stretched film.

The concentration of cellulose acetate in the dope is preferably higher because the drying load after casting on a metal support can be reduced. However, if the concentration of cellulose acetate is too high, the load during filtration increases and the filtration accuracy increases. Becomes worse. The concentration that achieves both of these is preferably 10 to 35% by mass, and more preferably 15 to 25% by mass. The metal support in the casting (casting) step preferably has a mirror-finished surface, and a stainless steel belt or a drum whose surface is plated with a casting is preferably used as the metal support.

The surface temperature of the metal support in the casting process is set to −50 ° C. to a temperature at which the solvent boils and does not foam. A higher temperature is preferred because the web can be dried faster, but if it is too high, the web may foam or the flatness may deteriorate.

A preferable support temperature is appropriately determined at 0 to 100 ° C., and more preferably 5 to 30 ° C. Alternatively, it is also a preferable method that the web is gelled by cooling and peeled from the drum in a state containing a large amount of residual solvent. The method for controlling the temperature of the metal support is not particularly limited, and there are a method of blowing hot air or cold air, and a method of contacting hot water with the back side of the metal support. It is preferable to use warm water because heat transfer is performed efficiently, so that the time until the temperature of the metal support becomes constant is short.

When using warm air, considering the temperature drop of the web due to the latent heat of vaporization of the solvent, while using warm air above the boiling point of the solvent, there may be cases where wind at a temperature higher than the target temperature is used while preventing foaming. . In particular, it is preferable to perform drying efficiently by changing the temperature of the support and the temperature of the drying air during the period from casting to peeling.

In order for the cellulose ester resin film to exhibit good flatness, the amount of residual solvent when peeling the web from the metal support is preferably 10 to 150% by mass, more preferably 20 to 40% by mass or 60 to 130%. % By mass, particularly preferably 20 to 30% by mass or 70 to 120% by mass.

The amount of residual solvent is defined by the following formula.

Residual solvent amount (% by mass) = {(MN) / N} × 100
Here, M is the mass of a sample collected at any time during or after the production of the web or long film, and N is a sample collected at any time during or after the production of the web or long film. It is the mass after heating at 1 ° C. for 1 hour.

In the drying step of the cellulose resin film, the web is preferably peeled off from the metal support and further dried to make the residual solvent amount 1% by mass or less, more preferably 0.1% by mass or less. Particularly preferably, it is 0 to 0.01% by mass or less.

In the film drying process, generally, a roll drying method (a method in which webs are alternately passed through a plurality of rolls arranged above and below) and a method in which the web is dried while being conveyed by a tenter method are employed.

<Melt casting method>
The melt casting method is a preferable film forming method from the viewpoint that it is easy to reduce the retardation Rt in the thickness direction after oblique stretching, the amount of residual volatile components is small, and the dimensional stability of the film is excellent. The melt casting method is a method in which a composition containing an additive such as a resin and a plasticizer is heated and melted to a temperature exhibiting fluidity, and then a melt containing fluid cellulose acetate is cast. The melt casting method can be classified into a melt extrusion molding method, a press molding method, an inflation method, an injection molding method, a blow molding method, a stretch molding method, and the like. Among these, the melt extrusion method is preferable, in which a long film having excellent mechanical strength and surface accuracy can be obtained.

It is preferable that a plurality of raw materials used for melt extrusion are usually kneaded and pelletized in advance.

Pelletization may be performed by a known method. For example, dry cellulose acetate, a plasticizer, and other additives are fed to an extruder with a feeder, kneaded using a single or twin screw extruder, and formed into a strand form from a die. Extrusion, water cooling or air cooling and cutting may be employed.

Additives may be mixed before being supplied to the extruder, or may be supplied by individual feeders.

A small amount of additives such as particles and antioxidants are preferably mixed in advance in order to mix uniformly.

The extruder is preferably processed at as low a temperature as possible so that it can be pelletized so as to suppress the shearing force and prevent the resin from deteriorating (molecular weight reduction, coloring, gel formation, etc.). For example, in the case of a twin screw extruder, it is preferable to rotate in the same direction using a deep groove type screw. From the uniformity of kneading, the meshing type is preferable.

Film formation is performed using the pellets obtained as described above. In addition, it is also possible to supply the raw material powder as it is to the extruder with a feeder and form a film as it is without pelletizing.

Using a single-screw or twin-screw type extruder, the melting temperature at the time of extrusion is about 200 to 300 ° C, filtered through a leaf disk type filter, etc. to remove foreign matter, and then formed into a film from the T die. And the film is nipped with a cooling roll and an elastic touch roll and solidified on the cooling roll.

When introducing from the supply hopper to the extruder, it is preferable to prevent oxidative decomposition or the like under vacuum or reduced pressure or in an inert gas atmosphere.

The extrusion flow rate is preferably carried out stably by introducing a gear pump. Further, a stainless fiber sintered filter is preferably used as a filter used for removing foreign substances. The stainless steel fiber sintered filter is a united stainless steel fiber body that is intricately intertwined and compressed, and the contact points are sintered and integrated. The density of the fiber is changed depending on the thickness of the fiber and the amount of compression, and the filtration accuracy is improved. Can be adjusted.

Additives such as plasticizers and particles may be mixed with the resin in advance, or may be kneaded in the middle of the extruder. In order to add uniformly, it is preferable to use a mixing apparatus such as a static mixer.

The film temperature on the touch roll side when the film is nipped by the cooling roll and the elastic touch roll is preferably Tg or more and Tg + 110 ° C. or less of the film. A well-known roll can be used for the roll which has the elastic body surface used for such a purpose.

The elastic touch roll is also called a pinching rotator. As the elastic touch roll, a commercially available one can be used.

When peeling the long film from the cooling roll, it is preferable to prevent the deformation of the long film by controlling the tension.

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

The long film formed by the above method is conveyed to the above stretching apparatus and stretched in an oblique direction.

The thickness of the long film is preferably 20 to 400 μm, more preferably 30 to 200 μm.

In this embodiment, the thickness unevenness σm in the flow direction of the long film supplied for stretching keeps the take-up tension of the long film at the above-described oblique stretching tenter inlet constant, and stabilizes the optical characteristics such as the orientation angle and retardation. From the viewpoint of reducing the thickness, it is preferably less than 0.30 μm, preferably less than 0.25 μm, more preferably less than 0.20 μm. When the thickness unevenness σm in the flow direction of the long film is 0.30 μm or more, variations in optical properties such as retardation and orientation angle of the long stretched film are remarkably deteriorated.

Further, a long film having a thickness gradient in the width direction may be supplied as the long film. The gradient of the thickness of the long film was experienced by stretching a long film with various thickness gradients experimentally so that the film thickness at the position where the stretching of the subsequent process was completed could be the most uniform. Can be obtained. The gradient of the thickness of the long film can be adjusted, for example, so that the thickness of the end on the thick side is about 0.5 to 3% thicker than the end on the thin side.

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

The preferable elastic modulus at the stretching temperature at the time of oblique stretching of the long film is 0.01 MPa or more and 5000 MPa or less, more preferably 0.1 MPa or more and 500 MPa or less, expressed as Young's modulus. If the modulus of elasticity is too low, the shrinkage rate during stretching and after stretching will be low, and wrinkles will be difficult to disappear.If it is too high, the tension applied during stretching will increase, and the part that holds both side edges of the long film will be It is necessary to increase the strength, and the load on the tenter in the subsequent process increases.

As the long film, a non-oriented film may be used, or a long film having an orientation in advance may be supplied. Further, if necessary, the width distribution of the orientation of the long film may be bowed, so-called bowing. That is, the orientation state of the long film can be adjusted so that the orientation of the long stretched film at the position where stretching in the subsequent step is completed can be made desirable.

(Oblique stretching process)
The oblique stretching process has already been described above. The long stretched film that has undergone the oblique stretching step is stretched obliquely in a direction greater than 0 ° and less than 90 ° with respect to the width direction of the long film. The stretched long stretched film is wound up by a subsequent winding process.

(Winding process)
The winding device is provided at the outlet of the oblique stretching device. By arranging the winding device so that the long stretched film can be pulled at a predetermined angle with respect to the stretching device, the take-up position and angle of the long stretched film can be finely controlled. It becomes possible to wind up a long stretched film with small variations. Therefore, the occurrence of wrinkles in the long stretched film can be effectively prevented, and the windability of the long stretched film is improved, so that the stretched film can be wound up in a long length. In the present embodiment, the take-up tension T (N / m) of the stretched long film can be adjusted between 100 N / m <T <300 N / m, preferably 150 N / m <T <250 N / m. preferable.

When the take-up tension is 100 N / m or less, slack and wrinkles of the long stretched film are likely to occur, and the retardation and the profile in the width direction of the orientation axis tend to deteriorate. On the other hand, when the take-up tension is 300 N / m or more, the variation in the orientation angle in the width direction is deteriorated, and the width yield (taking efficiency in the width direction) tends to be deteriorated.

In the present embodiment, it is preferable to control the fluctuation of the take-up tension T with an accuracy of less than ± 5%, preferably less than ± 3%. When the fluctuation of the take-up tension T is ± 5% or more, variations in optical characteristics in the width direction and the flow direction become large. As a method of controlling the fluctuation of the take-up tension T within the above range, the load applied to the first roll of the tenter outlet, that is, the tension of the long stretched film is measured, and the value is kept constant. And a method of controlling the rotation speed of the take-up roll by a different PID control method. Examples of the method for measuring the load include a method in which a load cell is attached to a bearing portion of a roll and a load applied to the roll, that is, a tension of a long stretched film is measured. As the load cell, a known tensile type or compression type can be used.

The stretched long film is released from the tenter exit after being held by the gripper, and is wound around a winding core (winding roll) to form a wound body of the long stretched film.

In addition, the both ends (both sides) of the long stretched film may be trimmed for the purpose of excising grip marks on both sides of the long stretched film held by the tenter gripping tool or obtaining a desired width. desirable.

The above trimming may be performed at once or may be performed in a plurality of times.

In addition, after winding up the long stretched film, the long stretched film is fed out again as necessary, trimming both ends of the long stretched film, and winding up again as a wound body of the long stretched film. Good.

Further, before winding, for the purpose of preventing blocking between the long stretched films, the masking film may be overlapped and wound up at the same time, or at least one of the long stretched films, preferably tapes or the like at both ends. You may wind up while bonding. The masking film is not particularly limited as long as it can protect the long stretched film, and examples thereof include a polyethylene terephthalate film, a polyethylene film, and a polypropylene film.

<Long stretched film>
The long stretched film obtained by the production method of the present embodiment has an orientation angle inclined in a range of greater than 0 ° and less than 90 ° with respect to the winding direction. Specific values can be appropriately selected depending on the application, and examples thereof include 15 °, 22.5 °, 45 °, 67.5 °, and 75 °.

The variation in the orientation angle in the width direction of the long stretched film obtained by the production method of the present embodiment is preferably 0.6 ° or less, more preferably 0.4 ° or less in a width of at least 1300 mm. is there. A long stretched film with an orientation angle variation exceeding 0.6 ° is bonded to a polarizer to obtain a circularly polarizing plate. When this is installed on a self-luminous image display device such as an organic EL display, Unevenness may occur.

The value of the in-plane retardation of the long stretched film obtained by the production method of the present embodiment is preferably 120 to 160 nm, more preferably 130 to 150 nm. By making the in-plane retardation value within the above range, it is possible to suppress external light reflection and improve display quality when used as a retardation film for a circularly polarizing plate for organic EL displays. Become.

The variation in the in-plane retardation of the long stretched film obtained by the production method of the present embodiment is preferably 3 nm or less, more preferably 1 nm or less, at least 1300 mm in the width direction. By setting the variation of the in-plane retardation within the above range, it is possible to suppress color unevenness when displaying a black screen when used as a retardation film for an organic EL display.

The optimum value of the in-plane retardation of the long stretched film obtained by the production method of the present embodiment is selected according to the design of the display device used. The in-plane retardation of the film is obtained by multiplying the difference between the refractive index nx in the in-plane slow axis direction and the refractive index ny in the direction orthogonal to the slow axis by the average thickness d of the long stretched film. Value ((nx−ny) × d).

The film thickness of the long stretched film obtained by the production method of the present embodiment is preferably 10 to 200 μm, more preferably 10 to 60 μm, and still more preferably from the viewpoint of mechanical strength and the like. Is 10 to 35 μm.

Further, the thickness unevenness in the width direction is preferably 3 μm or less, more preferably 2 μm or less, because it affects the availability of winding.

<Circularly polarizing plate>
The circularly polarizing plate of this embodiment has a polarizing plate protective film, a polarizer, a λ / 4 retardation film (long stretched film obtained in the above-described embodiment), and an adhesive layer laminated in this order. The angle formed by the slow axis of the λ / 4 retardation film and the absorption axis of the polarizer is 45 °.

In this embodiment, it is preferable that a long polarizing plate protective film, a long polarizer, and a long λ / 4 retardation film are laminated in this order.

The circularly polarizing plate can be produced by using a stretched polyvinyl alcohol doped with iodine or a dichroic dye as a polarizer, and laminating with a configuration of λ / 4 retardation film / polarizer.

The film thickness of the polarizer is 5 to 40 μm, preferably 5 to 30 μm, and particularly preferably 5 to 20 μm.

The polarizing plate can be produced by a general method. The λ / 4 retardation film subjected to the alkali saponification treatment is preferably bonded to one surface of a polarizer prepared by immersing and stretching a polyvinyl alcohol film in an iodine solution using a completely saponified polyvinyl alcohol aqueous solution.

The polarizing plate can be constituted by further bonding a release film on the opposite surface of the polarizing plate protective film of the polarizing plate. The protective film and the release film are used for the purpose of protecting the polarizing plate at the time of shipping the polarizing plate, product inspection, and the like.

<Embodiment with organic EL display>
Moreover, the circularly-polarizing plate using the elongate stretched film of above-mentioned embodiment is used especially preferably as a circularly-polarizing plate used for the reflection prevention use of a self-light-emitting display device like an organic EL display. The long stretched film according to the above-described embodiment is excellent in uniformity in the direction of the slow axis in the width direction (orientation angle). Therefore, when used in an organic EL display, particularly in color uniformity. An excellent display device can be obtained.

FIG. 13 shows an example of the configuration of the organic EL display D, but the present embodiment is not limited to this.

As shown in FIG. 13, the organic EL display D is an organic EL display having a metal electrode F2, a light emitting layer F3, a transparent electrode (ITO etc.) F4, and a sealing layer F5 on a substrate F1 made of glass, polyimide, or the like. On the element, an organic EL display is configured by providing a circularly polarizing plate with a polarizer F8 sandwiched between a λ / 4 retardation film F7 and a protective film F9 via an adhesive layer F6. It is preferable that a cured layer is laminated on the protective film F9. The cured layer not only prevents scratches on the surface of the organic EL display but also has an effect of preventing warpage due to the circularly polarizing plate. Further, an antireflection layer may be provided on the cured layer. The thickness of the organic EL element itself is about 1 μm.

Generally, in an organic EL display, a metal electrode, a light emitting layer, and a transparent electrode are sequentially laminated on a transparent substrate to form a light emitting element (organic EL element). Here, the light emitting layer is a laminate of various organic thin films, for example, a laminate of a hole injection layer made of a triphenylamine derivative and the like and a light emitting layer made of a fluorescent organic solid such as anthracene, or Structures with various combinations such as a laminate of such a light-emitting layer and an electron injection layer composed of a perylene derivative, and / or a laminate of these hole injection layer, light-emitting layer, and electron injection layer are known. ing.

In the organic EL display, holes and electrons are injected into the light emitting layer by applying a voltage to the transparent electrode and the metal electrode, and the energy generated by recombination of these holes and electrons excites the fluorescent material, It emits light based on the principle that it emits light when the excited fluorescent material returns to the ground state. The mechanism of recombination on the way is the same as that of a general diode, and as can be expected from this, the current and the light emission intensity show strong nonlinearity with rectification with respect to the applied voltage.

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

In the organic EL display having such a configuration, the light emitting layer is formed of a very thin film having a thickness of about 10 nm. For this reason, the light emitting layer transmits light almost completely like the transparent electrode. As a result, the light that is incident from the surface of the transparent substrate when not emitting light, passes through the transparent electrode and the light emitting layer, and is reflected by the metal electrode again exits to the surface side of the transparent substrate. The display surface of the EL display looks like a mirror surface.

The circularly polarizing plate made of a long stretched film obtained by the above embodiment is suitable for an organic EL display in which such external light reflection is particularly problematic.

The technical characteristics of the above-described method for producing a long stretched film are summarized below.

The method for producing a long stretched film according to one aspect of the present invention includes a step of forming a long film made of a thermoplastic resin, and a diagonal stretch from a specific direction different from the running direction of the film after stretching the long film. The slanted film is obliquely stretched in the direction of greater than 0 ° and less than 90 ° with respect to the width direction while feeding and feeding both ends of the long film with the gripping tool of the oblique stretching device. In the method for producing a long stretched film having at least a stretching step and a step of winding the long stretched film after the oblique stretching step, the oblique stretching device is oblique to the running direction of the long film before stretching. The stretching direction can be arbitrarily changed so that the travel direction of the long stretched film after stretching is in line, and a heating furnace and gripping tool travel supports provided on both sides of the long film are provided. The gripping tool travel support includes a drive shaft below a horizontal position where the long film travels, and in the oblique stretching step, the long film is at least in the stretching zone in the heating furnace. The heating is continuously performed by a planar heater provided between the drive shaft and the long film.

In the stretching apparatus used in the production method of the present invention, a planar heater is continuously provided between the drive shaft and the long film in the stretching zone where the long film is stretched. The planar heater can continuously heat a long film that travels without temperature unevenness, and can apply heat sufficiently and uniformly. Further, since the planar heater can uniformly apply heat to the long film, it is possible to prevent the occurrence of a collision wind. As a result, it is possible to produce a long stretched film with a small variation in the width direction of the orientation angle.

It is preferable that the long film is continuously heated by the planar heater throughout the heating furnace.

Thus, when the planar heater is provided throughout the heating furnace, the temperature unevenness of the long film is more reliably suppressed. As a result, regardless of the stretching angle, the variation in the width direction of the orientation angle of the obtained long stretched film is reduced, and a long stretched film with stable quality can be obtained.

The in-plane retardation of the obtained long stretched film is preferably 120 to 160 nm.

In the present invention, since the long film can be uniformly heated using the planar heater, the in-plane retardation of the obtained long stretched film can be within the above range. When such a long film is used for a circularly polarizing plate for an organic EL display, reflection of external light can be suppressed and image display quality is improved.

The thermoplastic resin is preferably a norbornene resin.

Long stretched films obtained using norbornene-based resins have low stretching stress, so even when they are conveyed at high speed, the occurrence of wrinkles and offsets at the ends of the long stretched films is reduced, and the orientation angle width is reduced. Variation in hand direction is suppressed.

The traveling speed of the gripping tool is preferably 15 to 150 m / min.

Generally, when the traveling speed of the gripping tool is within the above range, the long film is likely to have temperature unevenness due to insufficient heat supply. However, since the stretching device used in the production method of the present invention is continuously provided with a planar heater at least in the stretching zone, the long film that travels even when the long film is conveyed at high speed Heat can be applied sufficiently and uniformly. As a result, the variation in the width direction of the orientation angle of the obtained long film can be reduced.

The film thickness of the obtained long stretched film is preferably 10 to 35 μm.

In general, when the long film is a thin film, even if the temperature is slightly uneven, the orientation angle is likely to vary during stretching. However, the stretching apparatus used in the production method of the present invention has a planar heater at least in the stretching zone. Is provided continuously, and temperature unevenness of the long film can be effectively suppressed. Therefore, even if the film thickness of the obtained long stretched film is in the above range, variations in the width direction of the long stretched film orientation angle are suppressed.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

<Production of long film>
In the film forming process, long films A1 to C2 were prepared by the following method.

(Long film A1)
The long film A1 is an alicyclic olefin polymer resin film, and was produced by the following production method.

In a nitrogen atmosphere, 500 parts by mass of dehydrated cyclohexane, 1.2 parts by mass of 1-hexene, 0.15 parts by mass of dibutyl ether, and 0.30 parts by mass of triisobutylaluminum were mixed in a reactor at room temperature, and then mixed at 45 ° C. 20 parts by mass of tricyclo [4.3.0.12,5] deca-3,7-diene (dicyclopentadiene, hereinafter abbreviated as DCP), 1,4-methano-1,4,4a, 140 parts by mass of 9a-tetrahydrofluorene (hereinafter abbreviated as MTF) and 40 parts by mass of 8-methyl-tetracyclo [4.4.0.12, 5.17,10] -dodec-3-ene (hereinafter abbreviated as MTD) A norbornene-based monomer mixture composed of parts and 40 parts by mass of tungsten hexachloride (0.7% toluene solution) were continuously added over 2 hours for polymerization. To the polymerization solution, 1.06 parts by mass of butyl glycidyl ether and 0.52 parts by mass of isopropyl alcohol were added to deactivate the polymerization catalyst and stop the polymerization reaction.

Next, 270 parts by mass of cyclohexane is added to 100 parts by mass of the resulting reaction solution containing the ring-opening polymer, and 5 parts by mass of a nickel-alumina catalyst (manufactured by JGC Catalysts & Chemicals) is added as a hydrogenation catalyst. In addition, the pressure was increased to 5 MPa with hydrogen and the mixture was heated to 200 ° C. with stirring and then reacted for 4 hours to obtain a reaction solution containing 20% of a DCP / MTF / MTD ring-opening polymer hydrogenated polymer.

After removing the hydrogenation catalyst by filtration, a soft polymer (manufactured by Kuraray Co., Ltd .; Septon 2002) and an antioxidant (manufactured by Ciba Specialty Chemicals Co., Ltd .; Irganox 1010) were added to the resulting solutions, respectively. And dissolved (both 0.1 parts by mass per 100 parts by mass of the polymer). Next, cyclohexane and other volatile components, which are solvents, are removed from the solution using a cylindrical concentration dryer (manufactured by Hitachi, Ltd.), and the hydrogenated polymer is extruded in a strand form from an extruder in a molten state. After cooling, it was pelletized and collected. When the copolymerization ratio of each norbornene monomer in the polymer was calculated from the composition of residual norbornenes in the solution after polymerization (by gas chromatography method), it was almost charged at DCP / MTF / MTD = 10/70/20. It was equal to the composition. The hydrogenated product of this ring-opening polymer had a weight average molecular weight (Mw) of 31,000, a molecular weight distribution (Mw / Mn) of 2.5, and a hydrogenation rate of 99.9%.

The obtained ring-opened polymer hydrogenated pellets were dried at 70 ° C. for 2 hours using a hot air dryer in which air was circulated to remove moisture. Next, the pellets were subjected to a short-shaft extruder having a coat hanger type T die (manufactured by Mitsubishi Heavy Industries, Ltd .: screw diameter 90 mm, T die lip material is tungsten carbide, peel strength 44N from molten resin). A cycloolefin polymer film having a thickness of 75 μm (the thickness of the long film after drying obtained by the film forming process and not the thickness of the long stretched film produced through the stretching process) was manufactured by melt extrusion molding. . In extrusion molding, a long film A1 having a width of 1000 mm was obtained in a clean room of class 10,000 or less under molding conditions of a molten resin temperature of 240 ° C. and a T-die temperature of 240 ° C.

(Long film A2)
Among the methods for producing the long film A1, the thickness after melt extrusion is 35 μm (the thickness of the long film after drying obtained by the film forming step, and the length of the long stretched film produced through the stretching step. A long film A2 was obtained in the same manner as the long film A1, except that the die gap of the T die lip was appropriately adjusted so that the thickness was not.

(Long film B1)
The long film B1 is a cellulose ester resin film and was produced by the following production method.

<Fine particle dispersion>
Fine particles (Aerosil R972V manufactured by Nippon Aerosil Co., Ltd.) 11 parts by mass Ethanol 89 parts by mass The above was stirred and mixed with a dissolver for 50 minutes, and then dispersed with Manton Gorin.

<Fine particle additive solution>
Based on the following composition, the fine particle dispersion was slowly added to a dissolution tank containing methylene chloride with sufficient stirring. Further, the particles were dispersed by an attritor so that the secondary particles had a predetermined particle size. This was filtered through Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle additive solution.

99 parts by mass of methylene chloride 5 parts by mass of fine particle dispersion

<Main dope solution>
A main dope solution having the following composition was prepared. First, methylene chloride and ethanol were added to the pressure dissolution tank. Cellulose acetate was added to a pressurized dissolution tank containing a solvent while stirring. This was heated and completely dissolved while stirring, and this was dissolved in Azumi Filter Paper No. The main dope solution was prepared by filtration using 244. In addition, the compound synthesize | combined by the following synthesis examples was used for the sugar ester compound and the ester compound. Moreover, the following were used for the compound (B).

<Composition of main dope solution>
Methylene chloride 340 parts by mass Ethanol 64 parts by mass Cellulose acetate propionate (acetyl group substitution degree 1.39, propionyl group substitution degree 0.50, total substitution degree 1.89) 100 parts by mass Compound (B) 5.0 parts by mass Sugar ester compound 5.0 parts by mass Ester compound 2.5 parts by mass Particulate additive solution 1 part by mass

(Synthesis of sugar ester compounds)
A sugar ester compound was synthesized by the following steps.

Four-headed Kolben equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen gas inlet tube was charged with 34.2 g (0.1 mol) of sucrose, 180.8 g (0.6 mol) of benzoic anhydride, pyridine 379. 7 g (4.8 mol) was charged, the temperature was raised while bubbling nitrogen gas through a nitrogen gas inlet tube with stirring, and an esterification reaction was carried out at 70 ° C. for 5 hours.

Next, the inside of the Kolben was depressurized to 4 × 10 ² Pa or less, and after excess pyridine was distilled off at 60 ° C., the inside of the Kolben was depressurized to 1.3 × 10 Pa or less and the temperature was raised to 120 ° C. Most of the acid and benzoic acid formed were distilled off.

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

When the obtained mixture was analyzed by HPLC and LC-MASS, A-1 was 1.3% by mass, A-2 was 13.4% by mass, A-3 was 13.1% by mass, and A-4 was 31% by mass. 0.7% by mass and A-5 was 40.5% by mass. The average degree of substitution was 5.5.

<Measurement conditions for HPLC-MS>
1) LC section Equipment: Column oven (JASCO CO-965) manufactured by JASCO Corporation, detector (JASCO UV-970-240 nm), pump (JASCO PU-980), degasser (JASCO DG-980-50)
Column: Inertsil ODS-3 Particle size 5 μm 4.6 × 250 mm (manufactured by GL Sciences Inc.)
Column temperature: 40 ° C
Flow rate: 1 ml / min
Mobile phase: THF (1% acetic acid): H ₂ O (50:50)
Injection volume: 3 μl
2) MS unit Device: LCQ DECA (manufactured by Thermo Quest Co., Ltd.)
Ionization method: Electrospray ionization (ESI) method Spray Voltage: 5 kV
Capillary temperature: 180 ° C
Vaporizer temperature: 450 ° C

(Synthesis of ester compounds)
An ester compound was synthesized by the following steps.

251 g of 1,2-propylene glycol, 278 g of phthalic anhydride, 91 g of adipic acid, 610 g of benzoic acid, 0.191 g of tetraisopropyl titanate as an esterification catalyst, 2 L four-neck equipped with a thermometer, stirrer, and slow cooling tube The flask was charged and gradually heated with stirring until it reached 230 ° C. in a nitrogen stream. An ester compound was obtained by allowing dehydration condensation reaction for 15 hours, and distilling off unreacted 1,2-propylene glycol under reduced pressure at 200 ° C. after completion of the reaction. The ester compound had an ester of benzoic acid at the end of the polyester chain formed by condensation of 1,2-propylene glycol, phthalic anhydride and adipic acid. The acid value of the ester compound was 0.10, and the number average molecular weight was 450.

Then, using an endless belt casting apparatus, the casting was uniformly performed on a stainless belt support.

In the endless belt casting apparatus, the main dope solution was cast uniformly on a stainless steel belt support. The solvent is evaporated until the amount of residual solvent in the cast (cast) long film reaches 75%, peeled off from the stainless steel belt support, and dried while being transported by a number of rolls. A long film B1 was obtained. At this time, the film thickness of the long film B1 was 100 μm (the thickness of the long film after drying obtained in the film forming process, not the thickness of the long stretched film produced through the stretching process).

(Long film B2)
Among the methods for producing the long film B1, the thickness after the drying step is 50 μm (the thickness of the long film after drying obtained by the film forming step, and the thickness of the long stretched film produced through the stretching step. The long film B2 was obtained in the same manner as the long film B1, except that the film thickness at the time of casting was adjusted as appropriate.

(Long film C1)
The long film C1 is a polycarbonate resin film, and was produced by the following production method.

<Dope composition>
Polycarbonate resin (viscosity average molecular weight 40,000, bisphenol A type)
100 parts by mass 2- (2′hydroxy-3 ′, 5′-di-t-butylphenyl) -benzotriazole 1.0 part by mass Methylene chloride 430 parts by mass Methanol 90 parts by mass

The above composition was put into a sealed container, kept at 80 ° C. under pressure, and completely dissolved with stirring to obtain a dope composition.

Next, this dope composition was filtered, cooled and kept at 33 ° C., cast uniformly on a stainless steel band, and dried at 33 ° C. for 5 minutes. Thereafter, the drying time was adjusted so that the retardation was 5 nm at 65 ° C., and after peeling from the stainless steel band, drying was completed while being conveyed by a number of rolls, and the film thickness was 85 μm (after drying obtained by the film forming process). This is the thickness of the long film, not the thickness of the long stretched film produced through the stretching step), and a long film C1 having a width of 1000 mm was obtained.

(Long film C2)
Among the methods for producing the long film C1, the thickness at the time when the drying is finished is 40 μm (the thickness of the long film after drying obtained by the film forming process, which is produced through the stretching process. A long film C2 was obtained in the same manner as the long film C1, except that the film thickness at the time of casting was appropriately adjusted so that it was not the thickness of the stretched film.

<Production of long stretched film>
In the oblique stretching step and the winding step, the long films A1 to C2 were stretched by a diagonal stretching apparatus (T1 to T3) adjusted to the following conditions to form a long stretched film, and then wound into a roll shape. .

(Stretching device T1)
The stretching device T1 is shown in FIGS. In other words, the stretching apparatus T1 is provided with a planar heater between the drive shaft and the long film in the stretching zone of the heating furnace, and the long film F is continuously heated by the planar heater. The planar heater has a structure in which a stainless steel foil heater is attached to a polyimide film, and a heat generation density of 1 W / cm ² is continuously arranged along the stretching zone. The same number of gripping tools were provided on the gripping tool running support tools on both sides. The stretching device T1 has a configuration that can arbitrarily change the angle (stretching angle) formed by the feeding direction and the winding direction of the long film. The total length of the inner gripping tool travel support tool was 43 m. The overall length of the outer gripping tool travel support tool was 43 m.

The end trimming process of the long stretched film discharged from the stretching apparatus T1 was performed, and the final long stretched film was adjusted to have a film width of 1600 mm. Then, it wound up in roll shape with the take-up tension | tensile_strength 200 (N / m) with the winding device provided in the exit. The obtained long stretched film had a total length of 2000 m.

(Stretching device T2)
The stretching device T2 is shown in FIG. The stretching apparatus T2 has the same configuration as the stretching apparatus T1 except that a sheet heater is provided between the drive shaft and the long film along the path of the gripping tool travel support tool throughout the heating furnace. .

(Stretching device T3)
The stretching device T3 is shown in FIGS. The stretching device T3 has the same configuration as the stretching device T1 except that a total of five heating elements are arranged between adjacent drive shafts in the stretching zone instead of the planar heater described in the stretching device T1. Each heating element employed a common plenum duct for a tenter oven.

<Examples 1 to 6, Comparative Examples 1 to 3>
Based on the combinations shown in Table 1, the long films A1 to C1 were stretched by the stretching apparatuses T1 to T3. The stretching angles at this time were 22.5 ° and 45 °, and the long stretched films obtained at the respective stretching angles were long stretched films 1-1 to 9-2 (Examples 1 to 6, Comparative Examples 1 to 3). The traveling speed of the gripping tool at this time was 12 m / min. Moreover, as temperature conditions of the tenter oven when using the long film A1, the preheating zone was adjusted to 140 ° C, the stretching zone was 140 ° C, the heat setting zone was 137 ° C, and the cooling zone was adjusted to 80 ° C. Moreover, as temperature conditions of the tenter oven when the long film B1 was used, the preheating zone was adjusted to 180 ° C., the stretching zone was adjusted to 180 ° C., the heat setting zone was adjusted to 177 ° C., and the cooling zone was adjusted to 90 ° C. Moreover, as temperature conditions of the tenter oven when using the long film C1, the preheating zone was adjusted to 160 ° C, the stretching zone was adjusted to 160 ° C, the heat setting zone was adjusted to 157 ° C, and the cooling zone was adjusted to 80 ° C.

<Examples 7 to 9, Comparative Examples 4 to 6>
Based on the combinations shown in Table 2, the long films A1 to C1 were stretched by the stretching apparatuses T2 and T3. The stretching angles at this time were 22.5 ° and 45 °, and the long stretched films obtained at the respective stretching angles were long stretched films 10-1 to 15-2 (Examples 7 to 9, Comparative Examples 4 to 6). The traveling speed of the gripping tool at this time was 100 m / min. Moreover, as temperature conditions of the tenter oven when using the long film A1, the preheating zone was adjusted to 150 ° C., the stretching zone was 148 ° C., the heat setting zone was 144 ° C., and the cooling zone was adjusted to 90 ° C. Moreover, as temperature conditions of the tenter oven when using the long film B1, the preheating zone was adjusted to 187 ° C., the stretching zone was 187 ° C., the heat setting zone was 181 ° C., and the cooling zone was adjusted to 95 ° C. The temperature conditions of the tenter oven when the long film C was used were adjusted to 166 ° C. for the preheating zone, 166 ° C. for the stretching zone, 164 ° C. for the heat setting zone, and 90 ° C. for the cooling zone.

<Examples 10 to 12, Comparative Examples 7 to 9>
Based on the combinations shown in Table 3, the long films A2 to C2 were stretched by the stretching apparatuses T2 and T3. The stretching angles at this time were 22.5 ° and 45 °, and the long stretched films obtained at the respective stretching angles were long stretched films 16-1 to 21-2 (Examples 10 to 12, Comparative Examples 7 to 9). The traveling speed of the gripping tool at this time was 12 m / min. The temperature conditions of the tenter oven when using the long film A2 were adjusted to 140 ° C for the preheating zone, 140 ° C for the stretching zone, 137 ° C for the heat setting zone, and 80 ° C for the cooling zone. Moreover, as temperature conditions of the tenter oven when the long film B2 was used, the preheating zone was adjusted to 180 ° C, the stretching zone was adjusted to 180 ° C, the heat setting zone was adjusted to 177 ° C, and the cooling zone was adjusted to 90 ° C. Moreover, as temperature conditions of the tenter oven when using the long film C2, the preheating zone was adjusted to 160 ° C, the stretching zone was adjusted to 160 ° C, the heat setting zone was adjusted to 157 ° C, and the cooling zone was adjusted to 80 ° C.

<Example 13>
A 120 μm-thick polyvinyl alcohol film was uniaxially stretched (temperature: 110 ° C., stretch ratio: 5 times). This was immersed in an aqueous solution composed of 0.075 g of iodine, 5 g of potassium iodide and 100 g of water for 60 seconds, and then immersed in an aqueous solution of 68 ° C. composed of 6 g of potassium iodide, 7.5 g of boric acid and 100 g of water. This was washed with water and dried to obtain a polarizer.

The long film 1-2 was bonded to one side of the polarizer using a 5% aqueous solution of polyvinyl alcohol as an adhesive. In that case, it bonded so that the transmission axis of a polarizer and the slow axis of the produced elongate stretched film ((lambda) / 4 phase difference film) may become 45 degrees direction. On the other surface of the polarizer, Konica Minolta Tack Film KC6UA (manufactured by Konica Minolta Opto Co., Ltd.) was similarly subjected to alkali saponification treatment and bonded to produce a circularly polarizing plate 1.

(Creation of organic EL display)
A reflective electrode made of chromium having a thickness of 80 nm is formed on a glass substrate by sputtering, ITO (indium tin oxide) is formed as a positive electrode on the reflective electrode to a thickness of 40 nm by sputtering, and a polyelectrolyte is formed on the anode as a hole transport layer. (3,4-ethylenedioxythiophene) -polystyrene sulfonate (PEDOT: PSS) is formed by sputtering to form a light emitting layer for each of RGB with a thickness of 100 nm using a shadow mask on the hole transport layer. did.

For the red light emitting layer, tris (8-hydroxyquinolinate) aluminum (Alq ₃ ) as a host and a light emitting compound [4- (dicyanomethylene) -2-methyl-6 (p-dimethylaminostyryl) -4H-pyran] (DCM ) Were co-evaporated (mass ratio 99: 1) to form a thickness of 100 nm. The green light-emitting layer was formed with a thickness of 100 nm by co-evaporating Alq ₃ as a host and the light-emitting compound coumarin 6 (mass ratio 99: 1). The blue light-emitting layer was formed as a host by co-evaporating BAlq shown below and a light-emitting compound Perylene (mass ratio 90:10) with a thickness of 100 nm.

Further, as a first cathode having a low work function so that electrons can be efficiently injected onto the light-emitting layer, calcium is deposited to a thickness of 4 nm by a vacuum deposition method, and a second cathode is formed on the first cathode. Aluminum was formed to a thickness of 2 nm. Here, the aluminum used as the second cathode has a role to prevent the calcium as the first cathode from being chemically altered when the transparent electrode formed thereon is formed by sputtering. As described above, an organic light emitting layer was obtained. Next, a transparent conductive film with a thickness of 80 nm was formed on the cathode by sputtering. Here, ITO was used as the transparent conductive film. Further, an insulating film was formed by depositing silicon nitride with a thickness of 200 nm on the transparent conductive film by a CVD method (chemical vapor deposition method).

The light emitting area of the produced organic EL element was 1296 mm × 784 mm. Further, the front luminance when a DC voltage of 6 V was applied to the organic EL element was 1200 cd / m ² . The front luminance is measured using a spectral radiance meter CS-1000 manufactured by Konica Minolta Sensing Co., Ltd., so that the front luminance of the 2 ° C. viewing angle is aligned with the normal line from the light emitting surface. Then, the range of visible light wavelength of 430 to 480 nm was measured, and the integrated intensity was taken.

The circularly polarizing plate 1 is fixed on the insulating film of the organic EL element prepared above with an adhesive so that the surface of the prepared long stretched film (λ / 4 retardation film) faces the surface of the insulating film. An EL display 1 was produced (Example 13).

<Examples 14 to 24, Comparative Examples 10 to 18>
Circular polarizing plates 2 to 21 and organic EL displays 2 to 21 were produced using the long stretched films 2-2 to 21-2 in the same manner as in Example 13 (Examples 14 to 24, Comparative Example 10). To 18). It shows in Table 4 about the used elongate stretched film and the obtained organic electroluminescent display.

<Reference Example 1>
Using the prepared circular polarizing plate 7, the polarizing plate on the viewing side of a commercially available liquid crystal display panel (manufactured by Sony Corporation: model name BRAVIA KDL-26J5) is peeled off and bonded to the circular polarizing plate 7 prepared above. A liquid crystal panel was produced. Next, the liquid crystal panel was set on the liquid crystal television, and the liquid crystal display device 1 was produced.

<Reference Examples 2 to 3>
Liquid

crystal display devices

2 and 3 were produced in the same manner except that the circularly polarizing plate 7 was changed to circularly

polarizing plates

8 and 9 in the production of the liquid crystal display device 1. It shows in Table 5 about the used elongate stretched film and the obtained liquid crystal display device.

<Evaluation>
The following evaluation was performed about the obtained elongate stretched film.

(Orientation angle and width variation of orientation angle)
The orientation angles of the prepared long stretched films 1-1 to 21-2 were measured using a phase difference measuring apparatus (manufactured by Oji Scientific Co., Ltd., KOBRA-WXK).

(Evaluation criteria for variation of orientation angle in width direction)
A: The variation in the width direction of the orientation angle was less than 0.4 °.
A: The variation in the width direction of the orientation angle was 0.4 ° or more and less than 0.6 °.
Δ: The variation in the width direction of the orientation angle was 0.6 ° or more and less than 1.0 °.
X: The variation in the width direction of the orientation angle was 1.0 ° or more.

(In-plane retardation and lateral distribution of in-plane retardation)
In-plane retardation of the produced long stretched films 1-1 to 21-2 was measured using a phase difference measuring device (manufactured by Oji Scientific Co., Ltd., KOBRA-WXK). As an evaluation method, measurement was performed at an interval of 50 mm of the long stretched film in the film width direction of the long stretched film and evaluated.

The obtained organic EL display and liquid crystal display device were evaluated as follows.

(Color unevenness)
In the created organic EL display and liquid crystal display device, color unevenness on the entire display surface when black was displayed was visually evaluated according to the following criteria.

(Evaluation criteria for uneven color)
A: In the prepared organic EL display and liquid crystal display device, no difference was observed in the color of each part.
○: In the prepared organic EL display and liquid crystal display device, although there is a difference in color for each part, there was no problem in use.
(Triangle | delta): In the produced organic electroluminescent display and liquid crystal display device, the difference was seen in the color for every location, and it was the grade which cannot be used as a product.
X: In the produced organic electroluminescent display and liquid crystal display device, the color difference was large for every location and it was a grade which cannot be used as a product.

Tables 1 to 5 summarize the various elongated stretched films, organic EL displays, and liquid crystal display devices, and the results of various evaluations. In Tables 1 to 3, the film thickness, orientation angle, and in-plane retardation (in-plane Re) all indicate the physical property values of the obtained long stretched film.

As shown in Table 1, the long stretched films 1-1 to 6-2 corresponding to Examples 1 to 6 are compared with the long stretched films 7-1 to 9-2 corresponding to Comparative Examples 1 to 3. The variation in the width direction of the orientation angle was less than ± 0.6 °, which was good. In particular, the long stretched films 4-1 to 6-2 obtained using the stretching apparatus T2 were particularly good because the variation of the orientation angle in the width direction was less than ± 0.4 °.

As shown in Table 2, the elongated stretched films 10-1 to 12-2 corresponding to Examples 7 to 9 are compared with the elongated stretched films 13-1 to 15-2 corresponding to Comparative Examples 4 to 6. The variation in the width direction of the orientation angle was less than ± 0.6 °, which was good. In particular, the long stretched films 10-1 and 10-2 obtained using norbornene-based resins as the thermoplastic resins are particularly good because the variation of the orientation angle in the width direction is less than ± 0.4 °. there were.

As shown in Table 3, the long stretched films 16-1 to 18-2 corresponding to Examples 10 to 12 are compared with the long stretched films 19-1 to 21-2 corresponding to Comparative Examples 7 to 9. Thus, the variation in the width direction of the orientation angle was less than ± 0.6 °, which was good. In particular, the long stretched films 16-1 and 16-2 obtained using a norbornene-based resin as a thermoplastic resin are particularly good because the variation in the width direction of the orientation angle is less than ± 0.4 °. there were.

As shown in Table 4, are the organic EL displays 1 to 6 corresponding to Examples 13 to 18 different in color from the organic EL displays 7 to 9 corresponding to Comparative Examples 10 to 12? There was only a difference in color to the extent that there was no problem as a product, and it was good. In particular, the organic EL displays 4 to 6 obtained using the stretching apparatus T2 were particularly good with no difference in color.

Further, the organic EL displays 10 to 12 and the organic EL displays 16 to 18 corresponding to Examples 19 to 24 are compared with the organic EL displays 13 to 15 and the organic EL displays 19 to 12 corresponding to Comparative Examples 13 to 18. There was no difference in color, or there was only a difference in color to the extent that there was no problem as a product. In particular, the organic EL displays 10 and 16 prepared using a long stretched film obtained by using a norbornene-based resin as a thermoplastic resin were particularly good with no difference in color.

As shown in Table 5, the liquid crystal display devices 1 to 3 corresponding to Reference Examples 1 to 3 have no difference in color compared to the organic EL displays 7 to 9 corresponding to Comparative Examples 10 to 12, It was found that these problems are observed when a long stretched film is applied to an organic EL display.

The present invention can be widely used in technical fields such as a method for producing a long stretched film.

Claims

The step of forming a long film made of a thermoplastic resin, the long film is fed into an oblique stretching device from a specific direction different from the running direction of the stretched film, and both ends of the long film are obliquely stretched. An oblique stretching step in which the long film is obliquely stretched in a direction larger than 0 ° and less than 90 ° with respect to the width direction while being gripped and conveyed by a gripping tool, and a long stretched film after the oblique stretching step In the method for producing a long stretched film having at least a winding step,
The oblique stretching apparatus can arbitrarily change the stretching direction so that the traveling direction of the long stretched film after stretching is in the direction oblique to the traveling direction of the long film before stretching, and a heating furnace, A gripping tool travel support provided on both sides of the long film,
The gripping tool travel support tool includes a drive shaft below a horizontal position where the long film travels,
In the oblique stretching step, the long film is continuously heated by a planar heater provided between the drive shaft and the long film in at least a stretching zone in the heating furnace. A method for producing a stretched film.
The method for producing a long stretched film according to claim 1, wherein the long film is continuously heated by the planar heater throughout the heating furnace.
The method for producing a long stretched film according to claim 1 or 2, wherein the in-plane retardation of the obtained long stretched film is 120 to 160 nm.
The method for producing a long stretched film according to any one of claims 1 to 3, wherein the thermoplastic resin is a norbornene resin.
The method for producing a long stretched film according to any one of claims 1 to 4, wherein a traveling speed of the gripping tool is 15 to 150 m / min.
The method for producing a long stretched film according to any one of claims 1 to 5, wherein a film thickness of the obtained long stretched film is 10 to 35 µm.