TW201307036A - Stretched cellulose ester film and method for producing same - Google Patents

Abstract

The present invention addresses the problem of providing a stretched cellulose ester film, and a method for producing the same, whereby cellulose orientation defects are minimized in high-ratio stretching and broadening, and whereby trimming defects are unlikely to occur during high-speed conveyance, with little variance in the retardation value (Ro) in the in-plane direction in various parts of the film. This stretched cellulose ester film contains a cellulose ester that has a degree of acetyl group substitution in the range 2.8-2.95, wherein the stretched cellulose ester film is characterized in that part of the cross-sectional shape of surface (A) of the stretched cellulose ester film in the transverse direction is represented by a catenary curve, and the thickness difference (h) (maximum film thickness -film thickness at the ends) is in the range 1.0-4.0 [mu]m. As used herein, "surface (A)" refers to a surface opposite to the side in contact with a belt surface or a drum surface when a film dope is cast onto a belt or drum to form a film.

Description

Stretched cellulose ester film, and method of producing the same

The present invention relates to a stretched cellulose ester film and a method of producing the same.

Nowadays, the demand for liquid crystal display devices (hereinafter also referred to as LCDs) is also strong due to the spread of liquid crystal displays for automobiles, displays for large-sized liquid crystal televisions, mobile phones, and notebook computers. In the LCD, various optical films such as a polarizing film or a retardation film are used.

As the demand for LCDs increases, the polarizing plates used in conjunction with LCDs are also required to be thinned, lightweight, and highly productive. In addition, with the increase in the size of the LCD, it is required to increase the film properties of the optical film as a member due to the increase in film thickness and high productivity.

A cellulose ester film is widely used as a polarizing plate protective film. When a thin filmed and widened film is produced, in order to adjust optical characteristics or planarity, and the film thickness or width of the obtained film, it is generally after film formation. The stretching at a high magnification is performed by a tenter (for example, refer to Patent Document 1).

When the cellulose ester film is to be widened and thinned and stretched at a high rate at a high temperature, especially when a film having a width of more than 1.6 m is produced, it is easy to produce various portions of the film due to high-magnification stretching. The disorder of the cellulose alignment causes a trimming failure when transported at a high speed, and breaks even when it is severe. In addition, the retardation value Ro in the in-plane direction which is important in optical characteristics is thin. The variation in each portion of the film is increased, which causes problems in productivity and optical characteristics, and further improvement is expected.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2010-1383

The present invention has been made in view of the above problems and circumstances, and an object of the present invention is to provide a method of suppressing the disorder of cellulose alignment even when stretching is performed at a high magnification, and it is difficult to cause a trimming failure even at a high speed. Further, the retardation value Ro in the in-plane direction is a stretched cellulose ester film having a small variation in each portion of the film, and a method for producing the same.

In order to solve the above-mentioned problems, the inventors of the present invention have discovered the width direction of one surface in a stretched cellulose ester film containing a cellulose ester having a specific degree of substitution of a vinyl group. When a part of the upper cross-sectional shape is represented by a catenary curve and has a specific film thickness difference in the plane, it is possible to suppress the disorder of the cellulose alignment even if the film is stretched at a high magnification to form a wide width. The high-speed conveyance is also difficult to produce a trimming failure, and the cellulose ester film is stretched with a small change in the retardation value in the in-plane direction, and thus the present invention has been completed.

That is, the above problems of the present invention can be solved by the following means.

A stretched cellulose ester film comprising a stretched cellulose ester film of a cellulose ester having an ethyl ketone group substitution degree in the range of 2.8 to 2.95, characterized in that the stretched cellulose ester film A side A part of the cross-sectional shape in the width direction is represented by a catenary curve, and the film thickness difference h (film maximum film thickness - film end film thickness) is in the range of 1.0 to 4.0 μm.

Here, the above-mentioned A surface refers to a surface on the opposite side to one side of the steel strip surface or the drum surface when the fluid is cast on a steel strip or a drum in order to form a film coating material.

2. The stretched cellulose ester film according to Item 1, wherein an average value of arithmetic mean roughness (Ra) of a central portion of the surface of the stretched cellulose ester film is in the range of 2.2 to 3.5 nm, and The average value of the arithmetic mean roughness (Ra) of the end portion of the A-side of the stretched cellulose ester film is in the range of 0.3 to 1.0 nm.

Here, the term "end portion" means that when the full width of the stretched cellulose ester film is L, it is the portion from the end of the film to L × 0.05, and the central portion refers to the entire stretched cellulose ester film. When the width is L, the portion from the center of the film to the width direction is ± L × 0.1.

3. The drawn cellulose ester film according to Item 1 or 2, wherein the stretched cellulose ester film has a width in the range of 2 to 3 m, and the maximum film thickness of the film is in the range of 30 to 70 μm.

A method for producing a stretched cellulose ester film, which is a method for producing a stretched cellulose ester film according to any one of items 1 to 3, characterized in that the stretched cellulose ester film is formed. Coating to make the film A side A part of the cross-sectional shape in the width direction is formed by a catenary curve to form a film on a steel strip or a roll, and after peeling off, the surface temperature of the end portion of the film A surface is lowered. The stretching treatment is performed while being in the range of 10 to 50 ° C lower than the surface temperature of the central portion.

Here, the term "end portion" means the portion from the end of the film to Lo x 0.05 when the full width of the unstretched cellulose ester film is Lo, and the central portion refers to the unstretched cellulose ester film. When the full width is Lo, the portion from the center of the film to the width direction is ±Lo × 0.1.

5. The method for producing a stretched cellulose ester film according to item 4, wherein at least one pair of end cold air generating portions are provided for adjusting a surface temperature of the end portion, and one side is formed from the end portion cold air generating portion The temperature of the central portion is stretched toward the end portion by blowing cold air having a lower temperature in a range of 10 to 50 ° C lower.

6. The method for producing a stretched cellulose ester film according to Item 4 or 5, wherein the gas ambient temperature during the stretching treatment is in the range of 160 to 190 ° C, and is in the range of 25 to 100%. The draw ratio is stretched in the film width direction.

According to the present invention, it is possible to provide a widening of the stretching at a high rate, and it is possible to suppress the disorder of the cellulose alignment, and it is less likely to cause a trimming failure even at a high speed conveyance, and the retardation value Ro in the in-plane direction is in the film. A stretched cellulose ester film having a small variation in each portion, and a method for producing the same.

The visualization mechanism and mechanism of action of the present invention are still not fully understood. But it can be speculated as follows.

In the conventional cellulose ester film, the film thickness is uniformly designed and adjusted in the entire film. However, in the case of a wide width of 2 m or more, when the film is stretched at a high magnification and then transported at a high speed, there is no problem in the past. The beating of the diaphragm itself is increased, and it is easy to cause a trimming failure, and in severe cases, the problem of cracking frequently occurs.

As in the case of the stretched cellulose ester film of the present invention, by increasing the film thickness from the end portion toward the center portion of the film, the center of gravity of the film can be biased to the center portion, and as a result, even after stretching at a high magnification High-speed handling also suppresses the bounce of the diaphragm, thus suppressing the occurrence of trimming failure.

Further, by placing the center of gravity of the film in the center portion and suppressing the disorder of the cellulose alignment in the width direction during stretching, the retardation value Ro in the in-plane direction is small in the variation of each portion of the film. The cellulose ester film is stretched.

Hereinafter, the form for carrying out the invention will be described in detail, but the invention is not limited thereto.

The stretched cellulose ester film of the present invention is a stretched cellulose ester film containing a cellulose ester having an ethyl sulfonate degree of substitution in the range of 2.8 to 2.95, characterized in that the stretched cellulose ester film A is A part of the cross-sectional shape in the width direction is represented by a catenary curve, and the film thickness difference h (the film maximum film thickness - the film end film thickness) is in the range of 1.0 to 4.0 μm, and by this configuration, a high even height can be obtained. Stretching at a magnification to form a wide width, It is also less likely to cause a trimming failure, and the retardation value Ro in the in-plane direction is small to the stretched cellulose ester film on the portions of the film.

Here, the above-mentioned A surface refers to a surface on the opposite side to one side of the steel strip surface or the drum surface when the fluid is cast on a steel strip or a drum in order to form a film coating material.

This feature is a common feature in the invention of the patent application scope of claims 1 to 6.

According to the embodiment of the present invention, the average value of the arithmetic mean roughness (Ra) of the central portion of the surface A of the stretched cellulose ester film is in the range of 2.2 to 3.5 nm, and the effect of the present invention is exhibited. When the average value of the arithmetic mean roughness (Ra) of the end portion of the A-side of the stretched cellulose ester film is 0.3 to 1.0 nm, the beating of the film at the time of high-speed conveyance can be suppressed, and the effect of the present invention can be improved. It is preferred.

Further, in the case where the width of the stretched cellulose ester film is in the range of 2 to 3 m and the maximum film thickness of the film is in the range of 30 to 70 μm, it is a preferred embodiment.

As a method for producing the stretched cellulose ester film of the stretched cellulose ester film of the present invention, the coating of the stretched cellulose ester film is formed such that a part of the cross-sectional shape in the width direction of the film A is suspended. In the manner indicated by the chain curve, the fluid is cast on a steel strip or a drum to form a diaphragm, and after peeling, the surface temperature of the end portion of the diaphragm A surface is lowered to be lower than the surface temperature of the central portion. In the manufacturing method of the stretching process in the range of 10 to 50 ° C, the arithmetic mean roughness (Ra) of the center portion and the end portion can be controlled to a preferred range, and a high magnification can be performed. After the stretching, even if the conveyance is performed at a high speed, the runout of the film can be suppressed, which is preferable.

Further, at least a pair of end cold air generating portions are provided in order to adjust the surface temperature of the end portion, and from the end portion cold air generating portion, it is in a range of 10 to 50 ° C lower than the temperature of the central portion. A lower temperature cold air is blown toward the end portion, and a stretching process is preferred.

Further, when the gas ambient temperature at the time of the above stretching treatment is in the range of 160 to 190 ° C, and stretching is performed in the film width direction at a stretching ratio in the range of 25 to 100%, a wide drawing is obtained. A cellulose acetate film is a preferred method of manufacture.

The catenary curve will be described later, and Fig. 1 is a schematic view showing the cross-sectional shape of the stretched cellulose ester film of the present invention in the width direction.

Each symbol in Fig. 1 indicates F: a stretched cellulose ester film, A: A surface, B: B surface, Mh: maximum film thickness, Lh: end film thickness, and K: catenary curve.

In the present invention, the cellulose ester film after the stretching treatment is referred to as a "stretched cellulose ester film", and the cellulose ester film before the stretching treatment is referred to as "unstretched cellulose ester film" or "film." sheet".

The stretched cellulose ester film of the present invention is characterized in that a part of the cross-sectional shape in the width direction of the A surface is represented by a catenary curve, and as shown in Fig. 1, has a gentle curve with respect to the end portion of the film. Moreover, it has a cross section which becomes thick toward the center part. "A part of the cross-sectional shape in the width direction of the A surface" specifically refers to A which is represented by K in Fig. 1 The cross-sectional shape in the width direction of the surface.

The invention is described in detail below.

<Description of catenary curve>

The catenary curve in the present invention refers to a curve having one vertex and being line-symmetric with respect to a normal on the vertex.

The stretched cellulose ester film of the present invention is characterized in that a part of the cross-sectional shape of the A surface with respect to the width direction is expressed by a formula showing a catenary curve. A part of the cross-sectional shape of the A surface with respect to the width direction is as shown in Fig. 1, since the catenary curve is convex upward, the film thickness h relative to the width direction is inversed by the general catenary curve. The expression is expressed by the following formula (1).

Formula (1)h=-(e ^a +e ^-a )/2

Here, when the product width of the stretched cellulose ester film is x, a is changed within the range of -x/2≦a≦x/2.

A part of the cross-sectional shape of the A surface with respect to the width direction can be expressed by the formula (1), but in the present invention, when the film thickness difference between the end portion and the central portion of the film is h (the maximum film thickness of the film - the film thickness at the end of the film) ) is in the range of 1.0~4.0μm (that is, 1.0×10 ^-6 ~4.0×10 ^-6 (m)), and the condition that the product width x is changed within the range of 2~3m, to find more specific In the approximate expression, the relationship of the catenary curve of the present invention is expressed by the formula (2).

Equation (2)h(m)=-(e ^a +e ^-a )/b

In the formula, a varies within the range of -x/2≦a≦x/2(m), and b is in the range of 3.0 × 10 ⁵ ≦b ≦ 7.0 × 10 ⁵ . In the present invention, it can be determined that a part of the cross-sectional shape of the A surface with respect to the width direction is represented by a catenary curve when expressed by the above formula (2).

When the film thickness in the width direction of the A surface of the stretched cellulose ester film of the present invention is measured, for example, a contact type film thickness meter (Micrometer Minicom M manufactured by Tokyo Seimitsu Co., Ltd.) can be used, and the width direction is 10 cm from the end portion. The interval is measured and the thickness is determined. Further, a regression equation of the film thickness variation with respect to the width direction of the film can be obtained from the obtained film thickness value, and it can be determined whether or not the equation of the catenary curve can be expressed.

<Film film forming step>

In the present invention, after a coating fluid containing a cellulose ester and other additives is molded on a support (fluid casting step), it is peeled off from the support (peeling step), and then the peeled film is stretched ( The stretching step), drying (post-drying step), and then winding the film to a roll (winding step), through which the stretched cellulose ester film can be produced.

Referring to Fig. 2, the apparatus for producing a stretched cellulose ester film is provided with a support body composed of a rotating metal circulating steel strip, and a coating fluid mold for stretching a raw material solution of the cellulose ester film. The mold 2 on the support 1 and the peeling roll 3 which is peeled from the support 1 by the film W formed on the support 1 by the mold 2, and the film F peeled off from the support 1 in the width direction A tenter 4 having a cover that is conveyed and dried while being stretched, a drying device 5 that performs drying while transporting the film F via a plurality of conveying rollers 6, and a roll of the stretched cellulose ester film F obtained by drying Take the take-up roll 8.

Between the tenter 4 and the drying device 5 or between the drying device 5 and the take-up roll 8, a striping step (cutting) may be provided in order to form a desired product film width. The slitting device is disposed at the left and right end portions of the film, and the slitting device is constituted by a disk-shaped rotating upper blade and a roller-shaped rotating lower blade. When the stretched cellulose ester film is conveyed at a high speed, if the film jumps large, the quality of the slit profile of the end portion is deteriorated in this step, and a trimming failure or a breakage failure is likely to occur.

Further, in Fig. 2, before entering the stretching step by the tenter 4, the holding step 4-1 is set so that the temperature of the unstretched cellulose ester film Fo is not too low, or After the tenter 4 (stretching step), a cooling step 4-2 for slow cooling of the film is provided. Further, before entering the drying step by the drying device 5, the holding step 5-1 is set such that the temperature of the unstretched cellulose ester film Fo is not too low, or in the drying device 5 (drying step) After that, a cooling step 5-2 for performing gentle cooling of the film is provided.

<Fluid Casting Step>

The fluid casting step of the stretched cellulose ester film of the present invention is preferably such that the filtered paint is pumped through a pressurized quantitative gear pump to a pressurizing die, and at a position of the fluid casting film, from the pressurizing die The coating fluid is cast onto a metal support. In order to express the cross section (film thickness) in the width direction of the surface of the A surface by a catenary curve as in the present invention, a pressure mold which easily changes the flow rate in the width direction of the fluid casting film is preferable. The press mold is a hanger type mold or a T mold, and any of them can be preferably used, in order to improve In the film forming speed, two or more press molds can be placed on the metal support, and the amount of the coating material can be divided and laminated.

Specifically, the film thickness control represented by the catenary curve can control the paint concentration, the pumping liquid amount, the slit gap of the nozzle of the mold, the extrusion pressure of the mold, and the like, in such a manner as to have a desired thickness. The speed of the metal support and the temperature rise of the end portion are higher than the central portion to form a viscosity difference around the nozzle of the mold. Briefly, it is preferable to adjust the slit shape of the nozzle portion so that the shape of the surface of the diaphragm approximates a catenary curve to control the film thickness at the time of fluid casting.

<Stretching step>

Fig. 3 is an example showing the mechanism of the tenter 4. As shown in Fig. 3, in the tenter machine 4, a plurality of cymbals 11 are connected in a chain state on the left and right side portions of the outer cover 10, and the cymbals 11 form one wheel to travel on the rail 12, This is carried by holding the unstretched cellulose ester film Fo. Each of the cymbal sheets 11 is provided with a swayable pressing arm, and the both ends of the unstretched cellulose ester film Fo on the stage are placed on the left and right sides of the tenter 4 in the width direction. The curved distal end portion of the pressing arm of the tenter 4 is held (clamped) by the carrier, stretched and conveyed together, and dried.

In the tenter 4, the unstretched cellulose ester film Fo is successively passed through the film width holding area A, the film width direction stretching area B, and the stretched state in a state where both ends in the width direction are held. The film width maintaining area C is used for stretching treatment in the film width direction to obtain a stretched fiber. Vitamin E film F.

Here, in the tenter 4, the film width holding area A means that the distance between the holding pieces of the film width (both ends of the base layer) from the entrance of the tenter 4 to the stretching start point a is constant. region. Further, the stretched region B refers to the distance between the gripping blades of the film width (both ends of the base layer) from the stretching start point a of the tenter 4 to the stretching end point b toward the traveling direction (handling direction) Extended area. The film width holding area C in the stretched state refers to the gripping film width (the both ends of the base layer) after stretching from the stretching end point b of the tenter 4 to the holding of the crotch release point c. The distance between the areas is a certain area. In the latter half of the film width maintaining region C in the stretched state, when the stress applied in the width direction of the film F after the stretching treatment is too strong, it is preferable to provide a relaxation treatment.

The track 12 in the tenter 4 is generally a bendable track. By bending the track 12, the distance between the blades at the left and right ends can be changed to form the width maintaining area A, the stretching area B, and the width maintaining area. C. The stretching zone B corresponds to the stretching step of the present invention. Combinations of such areas are not limited to those illustrated, and may be combined in any order.

Further, the tenter 4 shown in the figure is a Brake type, but this may be another needle combing method, and in any manner, the width of the cellulose ester film F is stretched while being stretched. It is preferred to carry out the drying to improve the flatness and dimensional stability.

In order to achieve a widening, the stretched cellulose ester film of the present invention preferably stretches the unstretched cellulose ester film Fo in the film width direction by a stretching ratio in the range of 25 to 100%. As for productivity improvement and From the standpoint of avoiding breakage, the draw ratio is particularly preferably in the range of 30 to 50%.

The stretched cellulose ester film of the present invention is characterized in that a part of the cross-sectional shape of the A surface with respect to the width direction is represented by a catenary curve, and even if the stretching treatment is performed by the above-described stretching ratio, The cross-sectional shape is represented by a catenary curve, and a fluid-cast film is formed so that a part of the cross-sectional shape of the A surface of the unstretched film with respect to the width direction is represented by a catenary curve.

Further, the stretching operation is performed not only in the width direction (TD direction) of the film but also in the longitudinal direction (MD direction) of the film, and for example, a plurality of rolls are formed to form a peripheral speed difference between the rolls. a method for stretching the circumferential speed difference of the roll in the MD direction; fixing the both ends of the film by a bun or a needle comb, and expanding the interval of the bracts or the comb comb in the traveling direction to perform longitudinal stretching; Or a method of simultaneously expanding in the MD/TD direction and stretching in the MD/TD direction.

The film transporting tension in the film forming step in the tenter is preferably in the range of 120 to 200 N/m, more preferably 140 to 200 N/m, although it varies depending on the temperature. The optimum is in the range of 140 to 160 N/m.

The temperature at the time of stretching is preferably in the range of (Tg-30) to (Tg+100) °C when the glass transition temperature of the stretched cellulose ester film of the present invention is Tg, and more preferably (Tg- 20) ~ (Tg + 80) ° C range, more preferably (Tg-5) ~ (Tg + 20) ° C range. The Tg of the film can be determined by the method described in JIS K7121. Specific stretching treatment The temperature is preferably in the range of 160 to 190 °C. Preferably, the tenter machine 4 is entirely provided in the outer cover, and the hot air supply device (not shown) supplies the hot air to the outer cover so as to maintain the temperature while maintaining the temperature.

The stretching time can be appropriately selected, and from the viewpoint of planarity and dimensional stability, it is preferably a relatively short period of time. Specifically, it is preferably in the range of 1 to 10 seconds, and particularly preferably in the range of 4 to 10 seconds. Further, the stretching speed in the width direction can be maintained constant or changed. The stretching speed is preferably in the range of 50 to 500%/min, particularly preferably in the range of 100 to 400%/min, and most preferably in the range of 200 to 300%/min.

Figure 4 is a schematic view of a stretched cellulose ester film of the present invention.

The unstretched cellulose ester film Fo is conveyed to a tenter, and the end portion is held by a crepe sheet or the like, and is stretched at a predetermined draw ratio.

In the stretched cellulose ester film F of the present invention, the average value of the arithmetic mean roughness (Ra) of the end portion is different from the average value of the arithmetic mean roughness (Ra) of the central portion, and the aforementioned stretched cellulose ester film A The average value of the arithmetic mean roughness (Ra) of the central portion of the surface is in the range of 2.2 to 3.5 nm, and is 0.3 to 1.0 nm higher than the average value of the arithmetic mean roughness (Ra) of the end portion of the film A side. In the range, it is preferable from the viewpoint of reducing the runout on the roller during high-speed conveyance and further suppressing the trimming failure.

At the above end portion, when the full width of the stretched cellulose ester film is L, it means that the end portion of the stretched cellulose ester film is Ho to L × 0.05, and in Fig. 4, the range is H. . In addition, the central part, when stretching cellulose When the full width of the ester film is L, it means a portion of ± L × 0.1 in the width direction from the center portion (L/2) of the film, and the range T in Fig. 4 .

The average value of the arithmetic mean roughness (Ra) of the end portion means that 10 points are selected in the longitudinal direction with respect to the end portion (the above range H), and each arithmetic mean roughness (Ra) is measured and the average value is obtained.

The average value of the arithmetic mean roughness (Ra) of the center portion is obtained by selecting 10 points in the longitudinal direction for the center portion (the above range T), and measuring the arithmetic mean roughness (Ra) and obtaining the average value.

The arithmetic mean roughness (Ra) is a numerical value defined by JIS B 0601, and examples of the measurement method include a stylus method and an optical method.

The arithmetic mean roughness (Ra) of the present invention can be measured using a non-contact surface fine shape measuring device WYKO NT-2000.

Figure 5 is a schematic view showing the preferred stretching treatment method of the present invention.

In the preferred method for producing the stretched cellulose ester film of the present invention, the surface temperature of the end portion of the A-face of the unstretched cellulose ester film Fo is lowered to be lower than that of the unstretched cellulose ester film Fo. The surface temperature of the central portion is 10 to 50 ° C lower, and the stretching treatment is performed. However, it is not limited to this method. Here, the A side of the unstretched cellulose ester film Fo means that the liquid film is cast on the steel strip or the drum in order to form a film coating, and is opposite to the side contacting the steel strip surface or the drum surface. Face.

Here, the term "end portion" means that when the full width of the unstretched cellulose ester film Fo is Lo, it is the portion from the end of the film to Lo x 0.05, and the central portion refers to the unstretched cellulose ester. When the full width of the film Fo is Lo, it is thin The center portion of the film is a portion of ±Lo x 0.1 in the width direction.

The film surface temperature at the end and the center can be measured using a contact hand-held thermometer (ANRITSU DIGITAL THERMOMETER HA-100K). Specifically, five points were measured in the width direction of the point a where the stretching process was performed at the beginning of the film to be conveyed, and the average value was taken as the film temperature of the portion.

Thus, the arithmetic mean roughness (Ra) can be controlled within the aforementioned numerical range by changing the temperature at the end portion and the central portion at the time of the stretching treatment. This mechanism is still unpredictable, but it can be considered that the cellulose ester resin in the central portion can be softened by changing the temperature at the time of the above stretching treatment to a higher temperature at the center portion, and the polymerization of the cellulose ester resin is changed. Since the chain is arranged, the roughening agent tends to be present in the vicinity of the surface, and the arithmetic mean roughness (Ra) is changed.

The method of adjusting the temperature is preferably a method of partially blowing cold air to the end portion. Preferably, at least one pair of end cold air generating portions G1 may be provided, and a cold air generating portion is formed from the end portion to become In the method of lowering the surface temperature of the central portion by a temperature in the range of 10 to 50 ° C, a suitable cold air is blown to the end of the unstretched cellulose ester film Fo while stretching treatment is performed.

In the end portion cold air generating portion, it is preferable that the cold air having the controlled temperature is blown from the nozzle-shaped air outlet to the entire end portion of the unstretched cellulose ester film Fo by a cold air generating device (not shown). The area, the amount of air, the distance from the outlet to the end of the film, and the like can be appropriately selected, but it is preferable to cover at least the undrawn cellulose ester film in terms of position. Fo is the front and rear of point a where the stretching process is started. Further, in the region where the cold air is blown, when the full width of the unstretched cellulose ester film Fo is Lo, covering the end portion of the film to the portion of Lo × 0.2, the temperature adjustment of the end portion and the center portion can be efficiently performed. Therefore, it is better.

In the stretching step, the temperature distribution in the width direction of the ambient gas is small, and it is preferable from the viewpoint of improving the uniformity of the film, and the temperature distribution in the width direction of the end portion and the central portion is preferably ±5 ° C. Within the range of ±2 ° C, preferably within ± 1 ° C.

In Fig. 5, a pair of end cold air generating portions G1 are provided in the vicinity of the starting point a of the stretching treatment so as to cover both end portions of the unstretched cellulose ester film Fo. The position of the end portion cold air generating portion G1 in Fig. 5 shows a preferable position, but is not limited thereto.

Further, it is preferable to provide the end cold air generating portion G2 after the stretching end point b, and to increase the cold air temperature between the central portion temperature and the end temperature of the stretched cellulose ester film, thereby improving high-speed handling. Fitness.

The materials used in the present invention are explained below.

<Cellulose ester>

The cellulose ester used in the stretched cellulose ester film of the present invention has an average ethylidene group substitution degree in the range of 2.8 to 2.95. The average substitution ratio of the ethyl thiol group is particularly preferably in the range of 2.85 to 2.95. The method for determining the degree of substitution of the average ethyl thiol group of the cellulose ester can be determined in accordance with ASTM D-817-96.

The cellulose ester used in the present invention, as long as the above-mentioned ethyl hydrazine group is satisfied The cellulose ester is not particularly limited, and the cellulose ester may be a carboxylate having a carbon number of about 2 to 22 or an ester of an aromatic carboxylic acid, particularly preferably a lower fatty acid ester of cellulose. The lower fatty acid in the lower fatty acid ester of cellulose refers to a fatty acid having 6 or less carbon atoms. The thiol group bonded to the hydroxy group may be a straight chain or a branch or form a ring. In addition, other substituents may be substituted. When the degree of substitution is the same, when the number of carbon atoms is large, the birefringence is lowered. Therefore, it is preferably selected from a fluorenyl group having 2 to 6 carbon atoms. The carbon number of the cellulose ester is preferably from 2 to 4, particularly preferably from 2 to 3.

As the cellulose ester, a mercapto group derived from a mixed acid may be used, and a carbon number of 2 and 3 or a carbon number of 2 and 4 may be preferably used. In the present invention, the cellulose ester may be a cellulose propionate, a cellulose acetate butyrate or a cellulose acetate butyrate butylate which is bonded to a propionic acid group or a butyric acid group in addition to an ethyl sulfonate group. A mixed fatty acid ester of cellulose. The butyric acid group forming butyrate may be linear or branched.

The cellulose ester which can be particularly preferably used in the present invention is triacetyl cellulose having an average ethyl ketone group substitution degree in the range of 2.8 to 2.95.

When the degree of substitution of the ethyl thiol group is within the above range, the unreacted portion of the piperagose ring constituting the skeleton of the cellulose resin is less than the hydroxyl group, so that the residual amount of the hydroxyl group is small, whereby not only the dimensional change or the The occurrence of warpage and the occurrence of poor striping at the time of high-speed conveyance, and the physical properties as a binder are also high.

Further, when the degree of substitution of the average ethyl thiol group is within the above range, the disorder of the cellulose alignment at the time of stretching at a high magnification is small, and the effect of suppressing the variation of the phase difference is high.

The weight average molecular weight (Mw) of the cellulose ester of the present invention is preferably 75,000 or more, more preferably in the range of 75,000 to 300,000.

When the weight average molecular weight (Mw) of the cellulose ester resin is in the range of 75,000 to 300,000, heat resistance and brittleness are good and the viscosity range is appropriate, so that film formation is easy.

The weight average molecular weight (Mw) of the cellulose ester can be determined by the following manner.

It was measured by high performance liquid chromatography under the following conditions.

Solvent: dichloromethane

Pipe column: Shodex K806, K805, K803G (made by Showa Denko Co., Ltd., connected by three)

Column temperature: 25 ° C

Sample concentration: 0.1% by mass

Detector: RI Model 504 (made by GL Science)

Pump: L6000 (manufactured by Hitachi, Ltd.)

Flow rate: 1.0ml/min

Calibration curve: A calibration curve formed using 13 samples of standard polystyrene STK standard polystyrene (manufactured by Tosoh Corporation) Mw = 1000000 to 500. The 13 samples are preferably used at almost equal intervals.

The cellulose of the raw material of the cellulose ester used in the present invention is not particularly limited, and examples thereof include wood pulp (from coniferous trees, from broadleaf trees) or cotton linters. The Mw of the cellulose ester can be controlled by the type of cellulose or the use of a plurality of raw materials of cellulose. For example, when using broadleaf tree hydrolyzed cowhide When the pulp is esterified, the Mw of the cellulose ester tends to increase, and when the coniferous sulfite pulp is used, the Mw of the cellulose ester tends to be small. Therefore, cellulose may be used singly or in combination of two or more kinds, for example, conifer pulp and cotton or hardwood pulp may be used in combination. Cellulose, in many cases, the use of pulp (especially conifer pulp). The α-cellulose content (% by mass) of the cellulose is usually 94 to 99 (e.g., 95 to 99), preferably about 96 to 98.5 (e.g., 97.3 to 98).

The cellulose ester of the present invention, when the deuteration agent of the cellulose raw material is an acid anhydride (acetic anhydride, propionic anhydride, butyric anhydride), an organic solvent such as acetic acid or an organic solvent such as dichloromethane is used, and sulfuric acid is used. A protic catalyst is used to carry out the reaction. When the oxime agent is ruthenium chloride (CH ₃ COCl, C ₂ H ₅ COCl, C ₃ H ₇ COCl), an amine-like basic compound is used as a catalyst. Specifically, it can be synthesized by referring to the method described in JP-A-10-45804.

In addition, cellulose esters are also affected by trace metal components in cellulose esters. These components may be considered to be associated with the water used in the process, but the fewer components that may become insoluble cores, the better the metal ions of iron, calcium, magnesium, etc., sometimes with acidic groups that may contain organic The polymer decomposition product or the like forms a salt to form an insoluble matter, so that the less is better. The iron (Fe) component is preferably 1 ppm or less. The calcium (Ca) component is easily formed into a coordination compound, that is, a complex compound, with an acidic component such as a carboxylic acid or a sulfonic acid, or a complex amount of a ligand, and forms a scum derived from a large amount of insoluble calcium (insoluble) Precipitate, turbid).

The calcium (Ca) component is 60 ppm or less, preferably 0 to 30 ppm. Within the scope. The magnesium (Mg) component is preferably in the range of 0 to 70 ppm, and particularly preferably in the range of 0 to 20 ppm, since it is likely to be insoluble when it is too large. The metal component such as the content of the iron (Fe) component, the content of the calcium (Ca) component, and the content of the magnesium (Mg) component is extremely dried by a microwave digestion wet decomposition apparatus (decomposition of sulfuric acid) and alkali fusion. After the cellulose ester was pretreated, ICP-AES (inductively coupled plasma atomic emission spectrometer) was used for the analysis.

(plasticizer)

The stretched cellulose ester film of the present invention does not cause breakage upon stretching and gives the effect of the present invention, and it is preferred to contain an appropriate amount of a plasticizer as necessary. The plasticizer is not particularly limited, and is preferably selected from the group consisting of a polyol ester-based plasticizer, a polycarboxylic acid ester-based plasticizer, a glycolic acid-based plasticizer, a phthalate-based plasticizer, and a fatty acid ester-based plasticizer. Agents and polyester-based plasticizers, and acrylic plasticizers.

The polyol ester is a plasticizer composed of an ester of a divalent or higher aliphatic polyol and a monocarboxylic acid, and preferably has an aromatic ring or a cycloalkane ring in the molecule.

The polyol to be used can be represented by the following general formula (1).

General formula (1) R1-(OH) _n (wherein R1 represents an n-valent organic group, and n represents a positive integer of 2 or more)

Examples of preferred polyhydric alcohols include, for example, the following, but the present invention is not limited thereto. Ribool, arabitol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propylene glycol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1,2-butyl Alcohol, 1,3-butanediol, 1,4-butyl Glycol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol, 1,6-pentanediol, pentanetriol, galactitol, mannitol, 3-methyl Pentane-1,3,5-triol, pinacol, glucose alcohol, trimethylolpropane, trimethylolethane, xylitol, pentaerythritol, dipentaerythritol, and the like. Among them, trimethylolpropane and neopentyl alcohol are preferred.

The monocarboxylic acid to be used in the polyol ester is not particularly limited, and generally known aliphatic monocarboxylic acids, alicyclic monocarboxylic acids, aromatic monocarboxylic acids and the like can be used. When an alicyclic monocarboxylic acid or an aromatic monocarboxylic acid is used, it is preferable from the viewpoint of improving moisture permeability and retention. Examples of preferred monocarboxylic acids include, for example, the following, but are not limited thereto.

As the aliphatic monocarboxylic acid, a fatty acid having a linear or side chain having 1 to 32 carbon atoms is preferably used. More preferably, the carbon number is from 1 to 20, and the carbon number is from 1 to 10. When acetic acid is used, it is preferable to increase the compatibility with the cellulose ester, and it is preferred to use acetic acid and other monocarboxylic acids in combination.

Preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, heptanoic acid, caprylic acid, capric acid, capric acid, 2-ethyl-hexanoic acid, undecanoic acid, and ten. Diacid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, palmitic acid, heptadecanoic acid, octadecanoic acid, nineteen acid, twenty acid, behenic acid, tetracosic acid, twenty-six acid, Saturated fatty acids such as octadecanoic acid, octadecanoic acid, tridecanoic acid, tridecanoic acid, etc., unsaturation of undecylenic acid, oleic acid, hexenoic acid, linoleic acid, linoleic acid, peanut oleic acid, etc. fatty acid. Examples of preferred alicyclic monocarboxylic acids include cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, cyclooctanecarboxylic acid, and the like. Examples of preferred aromatic monocarboxylic acids include benzoic acid, toluic acid, and the like, which are introduced into the benzene ring of benzoic acid. An aromatic monocarboxylic acid having two or more benzene rings, such as a base, a biphenylcarboxylic acid, a naphthalenecarboxylic acid or a tetraphosphoric acid, or a derivative thereof. Particularly preferred is benzoic acid.

The molecular weight of the polyol ester is preferably in the range of 300 to 1,500, more preferably in the range of 350 to 750. The larger molecular weight is less volatile, so it is preferred, and the smaller one is preferable from the viewpoint of moisture permeability and compatibility with cellulose ester. The carboxylic acid to be used in the polyol ester may be used alone or in combination of two or more. Further, the OH group in the polyol ester may be all esterified or partially retained as an OH group. The following are exemplified by specific compounds of the polyol ester.

Other, trimethylolpropane triacetate, neopentyl glycol tetraacetate or the like can also be preferably used.

The glycolic acid ester plasticizer is not particularly limited, and an alkyl phthalate alkyl phthalate is preferably used. Alkyl phthalic acid alkyl acetates, Examples thereof include methyl hydroxyacetate, ethyl hydroxyethyl phthalate, propyl propyl phthalate, butyl butyl phthalate, and octyl. Octyl phthalate, ethyl hydroxyethyl phthalate, methyl glycol phthalate, ethyl hydroxyacetate, glycolic acid glycolic acid Butyl ester, ethyl butyl phthalate, methyl butyl phthalate, ethyl hydroxy phthalate, butyl hydroxy phthalate, butyl Propyl hydroxyacetate, octyl hydroxyacetate, octyl hydroxyacetate, methyl octyl phthalate, octyl phthalate Ester and the like.

A phthalate-based plasticizer, which may be exemplified by diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, ortho-benzene. Dibutyl dicarboxylate, di-2-ethylhexyl phthalate, dioctyl phthalate, dicyclohexyl phthalate, dicyclohexyl terephthalate, and the like.

Examples of the citrate-based plasticizer include ethoxylated trimethyl citrate, ethionyl triethyl citrate, and ethyl tributyl citrate.

Examples of the fatty acid ester-based plasticizer include butyl octadecacrylate, methyl phthalate of ricinoleic acid, and dibutyl sebacate.

Phosphate-based plasticizers, such as triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl Phosphate ester, tributyl phosphate, and the like.

The polyvalent carboxylate compound is composed of an ester of a polyvalent carboxylic acid having a valence of 2 or more, preferably 2 to 20 valents, and an alcohol. In addition, aliphatic polycarboxylic acid When the ratio is 2 to 20, the alicyclic polycarboxylic acid or the aromatic polycarboxylic acid is preferably 3 to 20 valence.

The polycarboxylic acid can be represented by the following general formula (2).

General formula (2) R2(COOH) _m (OH) _n (R2 represents an (m+n) valence organic group, m represents a positive integer of 2 or more, n represents an integer of 0 or more, COOH represents a carboxyl group, and OH group represents Alcoholic and/or phenolic hydroxyl groups)

Examples of preferred polyvalent carboxylic acids include the following, but the present invention is not limited thereto. Preferably, a trivalent or higher aromatic polycarboxylic acid such as trimellitic acid, trimellitic acid or pyromic acid or a derivative thereof; succinic acid, adipic acid, sebacic acid, sebacic acid, oxalic acid, Fumaric acid, maleic acid, tetrahydrophthalic acid-like aliphatic polycarboxylic acid; tartaric acid, hydroxymalonic acid, malic acid, citric acid-like oxypolycarboxylic acid, and the like. In particular, those using an oxypolycarboxylic acid are preferred from the viewpoints of improvement in retention and the like.

The alcohol to be used in the polyvalent carboxylate compound of the present invention can be used without particular limitation, and generally known alcohols and phenols can be used. For example, an aliphatic saturated alcohol or an aliphatic unsaturated alcohol having a linear or side chain having a carbon number of 1 to 32 can be preferably used. More preferably, the carbon number is from 1 to 20, and the carbon number is from 1 to 10. Further, an alicyclic alcohol such as cyclopentanol or cyclohexanol or the like, an aromatic alcohol such as benzyl alcohol or cinnamyl alcohol or the like may be preferably used.

When an oxypolycarboxylic acid is used as the polycarboxylic acid, a monocarboxylic acid can be used to esterify the alcoholic or phenolic hydroxyl group of the oxypolycarboxylic acid. Examples of preferred monocarboxylic acids include, for example, the following, but the present invention is not limited thereto.

As the aliphatic monocarboxylic acid, a fatty acid having a linear or side chain having 1 to 32 carbon atoms is preferably used. More preferably, the carbon number is from 1 to 20, and the carbon number is from 1 to 10.

Preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, heptanoic acid, caprylic acid, capric acid, capric acid, 2-ethyl-hexanecarboxylic acid, and undecylic acid. , dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, palmitic acid, heptadecanoic acid, octadecanoic acid, nineteen acid, twenty acid, twenty acid, twenty-four acid, twenty-six a saturated fatty acid such as acid, toluic acid, octadecanoic acid, tridecanoic acid or tridecanoic acid, undecylenic acid, oleic acid, hexadienoic acid, linoleic acid, linoleic acid, peanut oleic acid, etc. Unsaturated fatty acids, etc.

Examples of preferred alicyclic monocarboxylic acids include cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, cyclooctanecarboxylic acid, and the like.

Examples of the preferred aromatic monocarboxylic acid include those in which an alkyl group is introduced into a benzene ring of benzoic acid such as benzoic acid or toluic acid, or a biphenylcarboxylic acid, a naphthalenecarboxylic acid or a tetraphosphoric acid. The above aromatic monocarboxylic acid of the benzene ring, or a derivative thereof. Particularly preferred are acetic acid, propionic acid, and benzoic acid.

The molecular weight of the polyvalent carboxylate compound is not particularly limited, and the molecular weight is preferably in the range of 300 to 1,000, more preferably in the range of 350 to 750. From the viewpoint of retention, the larger one is preferable, and the smaller one is preferable from the viewpoint of moisture permeability and compatibility with the stretched cellulose ester.

The alcohol to be used in the polycarboxylic acid ester of the present invention can be used singly or in combination of two or more kinds.

The acid value of the polyvalent carboxylate compound of the present invention can be used, preferably 1 mgKOH/g or less, more preferably 0.2 mgKOH/g or less. By acid value It is preferable to set the above range to suppress the environmental fluctuation of the retardation.

(acid value)

The acid value refers to the number of milligrams of potassium hydroxide required to neutralize the acid contained in the sample 1 g (the carboxyl group present in the sample). The value of the acid value is a value measured in accordance with JIS K0070.

Examples of the particularly preferable polyvalent carboxylate compound are as follows, but the present invention is not limited thereto. For example, triethyl citrate, tributyl citrate, ethoxylated triethyl citrate (ATEC), butyl citrate tributyl acrylate (ATBC), benzhydryl tributyl tributyl citrate, Ethyl citrate triphenyl ester, acetyl citrate tribenzyl ester, dibutyl tartrate, dibutyl butyl tartrate, tributyl trimellitate, tetrabutyl pyromelliate, and the like.

(sugar ester compound)

The stretched cellulose ester film of the present invention contains a sugar ester compound represented by the following general formula (3) (in the present invention, a sugar ester compound other than a cellulose ester is referred to as a sugar ester compound), thereby preventing stretching It is preferred that the resulting haze promotes a uniform phase difference.

(wherein R ₁ to R ₈ represent a hydrogen atom, a substituted or unsubstituted alkylcarbonyl group having 2 to 22 carbon atoms, or a substituted or unsubstituted arylcarbonyl group having 2 to 22 carbon atoms; and R ₁ to R ₈ may be Same or different)

The compound represented by the general formula (3) used in the present invention has an average degree of substitution of 3.0 to 6.5, and is effective in suppressing an increase in haze during stretching treatment and exhibiting a uniform phase difference. The average degree of substitution is particularly preferably in the range of 4.5 to 6.5.

In the present invention, the degree of substitution of the compound represented by the general formula (3) refers to the number of substituents other than hydrogen among the eight hydroxyl groups contained in the general formula (3), that is, in the general formula ( 3) R ₁ to R ₈ contain the number of groups other than hydrogen. Therefore, when all of R ₁ to R ₈ are substituted by a substituent other than hydrogen, the maximum degree of substitution is 8.0, and when all of R ₁ to R ₈ are a hydrogen atom, it is 0.0.

The compound represented by the general formula (3) is a compound in which it is difficult to synthesize the number of hydroxyl groups and the number of OR groups is fixed, and it is known that the number of hydroxyl groups and the number of OR groups in a plurality of formulas are mixed. It is a compound of a different component. Therefore, the degree of substitution of the general formula (3) in the present invention is preferably an average degree of substitution, and the degree of substitution can be exhibited by high-speed liquid chromatography by a general method. The area ratio of the distribution map is used to determine the average degree of substitution.

Examples of the sugar of the synthetic raw material of the sugar ester compound used in the present invention include, for example, the following, but the present invention is not limited thereto.

Glucose, galactose, mannose, fructose, xylose, or arabinose, lactose, sucrose, cane sugar, 1F-cane fruit pentose, stachyose, maltitol, lactitol, lactulose, cellobiose Maltose, fiber trisaccharide , maltotriose, raffinose or cane fruit trisaccharide.

Other examples include gentiobiose, gentian trisaccharide, gentian tetrasaccharide, xylotriose, and galactose sucrose.

The monocarboxylic acid to be used in the synthesis of the sugar ester compound used in the present invention is not particularly limited, and generally known aliphatic monocarboxylic acids, alicyclic monocarboxylic acids, aromatic monocarboxylic acids and the like can be used. The monocarboxylic acid to be used may be one type or a mixture of two or more types.

Examples of preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, heptanoic acid, caprylic acid, capric acid, capric acid, 2-ethyl-hexanoic acid, Undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, palmitic acid, heptadecanoic acid, octadecanoic acid, nineteen acid, twenty acid, behenic acid, tetracosic acid, Saturated fatty acids such as hexadecanoic acid, octadecanoic acid, octadecanoic acid, tridecanoic acid, and tridecanoic acid, undecylenic acid, oleic acid, hexadienoic acid, linoleic acid, linoleic acid, peanut oil An unsaturated fatty acid such as an acid or an octenoic acid.

Examples of preferred alicyclic monocarboxylic acids include cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, cyclooctanecarboxylic acid, and the like.

Examples of preferred aromatic monocarboxylic acids include aromatic monocarboxylic acids, cinnamic acid, and diphenyl groups in which 1 to 5 alkyl groups or alkoxy groups are introduced into a benzene ring of benzoic acid such as benzoic acid or toluic acid. An aromatic monocarboxylic acid having two or more benzene rings, such as glycolic acid, a biphenylcarboxylic acid, a naphthalenecarboxylic acid or a tetraphosphoric acid, or a derivative thereof, particularly preferably benzoic acid.

A part of a specific example of the sugar ester compound represented by the general formula (3) is as follows. However, all of R ₁ to R _{8 are the} same substituent R, and the present invention is not limited thereto. In the following table, when the average degree of substitution is less than 8.0, it means that some of R ₁ to R ₈ are a hydrogen atom.

The sugar ester compound used in the present invention can be produced by reacting a sulfating agent (also referred to as an esterifying agent such as an oxime halide of acetonitrile, an anhydride such as acetic anhydride) with a sugar, and the degree of substitution. The distribution can be adjusted by adjusting the amount of the oximation agent, the timing of addition, and the esterification reaction time, by mixing a sugar ester compound having a different degree of substitution, or by mixing a compound having a different degree of substitution after pure isolation. The average degree of substitution for the purpose of adjustment and the degree of substitution are 4 or less.

(Synthesis Example: Synthesis of Compound of the Present Invention)

34.2 g (0.1 mol) of sucrose, 135.6 g (0.6 mol) of benzoic anhydride, and 284.8 g (3.6 mol) of pyridine were placed in a four-necked flask equipped with a stirring device, a reflux cooling tube, a thermometer, and a nitrogen introduction tube. Under stirring The nitrogen gas was introduced from the nitrogen gas introduction tube, and the temperature was raised while foaming, and the esterification reaction was carried out at 70 ° C for 5 hours.

Next, the pressure in the flask was reduced to 4 × 10 ² Pa or less, and after the excess pyridine was distilled off at 60 ° C, the pressure inside the flask was reduced to 1.3 × 10 Pa or less, the temperature was raised to 120 ° C, and benzoic anhydride was distilled off and produced. The majority of benzoic acid. Then, 300 g of 1 L of toluene and 0.5% by mass of a sodium carbonate aqueous solution were added, and the mixture was stirred at 50 ° C for 30 minutes, and then allowed to stand, and the toluene layer was fractionated. Finally, 100 g of water was added to the fractionated toluene layer, and after washing at room temperature for 30 minutes, the toluene layer was fractionated, and under reduced pressure (4 × 10 ² Pa or less), toluene was distilled off at 60 ° C to obtain a compound A- A sugar ester compound 1 of a mixture of A-2, A-3, A-4 and A-5.

The obtained mixture was analyzed by high performance liquid chromatography-mass spectrometry (HPLC-MS), and it was found that A-1 was 1.2% by mass, A-2 was 13.2% by mass, and A-3 was 14.2% by mass. -4 is 35.4% by mass, and A-5 or the like is 40.0% by mass. The average degree of substitution is 5.2.

Similarly, 158.2 g (0.7 mol), 146.9 g (0.65 mol), 135.6 g (0.6 mol), and 124.3 g (0.55 mol) of benzoic anhydride were reacted with the pyridine of the molar to obtain the first The sugar ester of the component described in Table 1.

Then, a part of the obtained mixture is purified by using a cerium oxide gel column chromatography to obtain A-1, A-2, A-3, A-4 and A-5 having a purity of 100%, respectively. Wait.

A-5 or the like refers to a mixture of all the components having a degree of substitution of 4 or less, that is, a compound having a degree of substitution of 4, 3, 2, and 1. Further, the average degree of substitution is calculated by substituting 4 to calculate A-5 and the like.

In the present invention, the average degree of substitution is adjusted by combining the sugar esters close to the desired average degree of substitution and the separated A-1 to A-5 by the production method described herein.

<Measurement conditions of HPLC-MS>

1) LC department

Device: JASCO CO-965, detector (JASCO UV-970-240nm), pump (JASCO PU-980), degassing device (JASCO DG-980-) 50)

Column: Inertsil ODS-3 particle size 5 μm 4.6 × 250 mm (manufactured by GL Sciences Co., Ltd.)

Column temperature: 40 ° C

Flow rate: 1ml/min

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

Injection volume: 3μl

2) MS Department

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

Ionization: Electrospray Ionization (ESI)

Spray Voltage: 5kV

Capillary temperature: 180 ° C

Vaporizer temperature: 450 ° C

The stretched cellulose ester film of the present invention is preferably in the range of 1 to 20% by mass, particularly preferably in the range of 3 to 15% by mass. When it is in this range, the excellent effect of the present invention which is stabilized by the retardation can be exhibited, and bleeding or the like does not occur in the storage of the rolled material, which is preferable.

(polyester compound)

The stretched cellulose ester film of the present invention contains a polyester compound represented by the following general formula (4), and it is preferable to suppress the haze or breakage due to stretching.

The polyester compound is preferably used in a polyester compound having an aromatic ring or a cycloalkane ring in the molecule. As the polyester-based compound, an aromatic terminal ester-based plasticizer represented by the following general formula (4) is preferably used.

General formula (4) B-(GA) _n -GB (wherein B represents a benzene monocarboxylic acid residue, G represents an alkanediol residue having a carbon number of 2 to 12 or an aromatic diol residue having a carbon number of 6 to 12 a group or a residual group of oxyalkylene glycol having 4 to 12 carbon atoms, A represents an alkanedicarboxylic acid residue having 4 to 12 carbon atoms or an aromatic dicarboxylic acid residue having 6 to 12 carbon atoms, and n represents an integer of 1 or more)

In the general formula (4), it is: a residue of a benzene monocarboxylic acid represented by B and an alkanediol residue represented by G or an oxyalkylene glycol residue or an aromatic diol residue, and an alkane represented by A The carboxylic acid residue or the aryl dicarboxylic acid residue can be obtained by the same reaction as a general polyester plasticizer.

The benzene monocarboxylic acid component of the polyester plasticizer, for example, benzoic acid, benzoic acid to tert-butyl butyl ester, o-toluic acid, m-toluic acid, p-toluic acid, dimethyl benzoate, ethyl benzoate, benzoic acid N-propyl ester, benzoic acid amine ester, acetoxy benzoate or the like may be used alone or in combination of two or more kinds.

The polyester-based plasticizer has an alkanediol component having 2 to 12 carbon atoms, and is ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, and 1,3-butanediol. 1,2-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (neopentethylene) Alcohol), 2,2-dimethyl-1,3-propanediol (3,3-dihydroxymethylpentane), 2-n-butyl-2-ethyl-1,3-propanediol (3,3- Dimethylol heptane), 3-methyl-1,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-B Base-1,3-hexanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-nonanediol, 1,12-octadecanediol, etc. These diols may be used alone or in combination of two or more. In particular, an alkanediol having a carbon number of 2 to 12 is particularly excellent in compatibility with a cellulose ester.

Further, the oxyalkylene glycol component having 4 to 12 carbon atoms of the aromatic terminal ester may, for example, be diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol or tripropylene glycol, and these diols may be used. One type or a mixture of two or more types.

The alkanedicarboxylic acid component having 4 to 12 carbon atoms of the aromatic terminal ester, for example, succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, sebacic acid, sebacic acid, dodecane For the carboxylic acid or the like, one type or a mixture of two or more types may be used. The aryldicarboxylic acid component having 6 to 12 carbon atoms includes phthalic acid, terephthalic acid, isophthalic acid, 1,5-naphthalene dicarboxylic acid, and 1,4-naphthalenedicarboxylic acid.

The polyester-based plasticizer preferably has a number average molecular weight of from 300 to 1,500, more preferably from 400 to 1,000. Further, the acid value is preferably 0.5 mgKOH/g or less, and the hydroxyl value is 25 mgKOH/g or less. More preferably, the acid value is 0.3 mgKOH/g or less, and the hydroxyl value is 15 mgKOH/g or less.

The following is a synthesis example of an aromatic terminal ester type plasticizer.

<Sample No. 1 (aromatic terminal ester sample)>

410 parts of phthalic acid, 610 parts of benzoic acid, 737 parts of dipropylene glycol, and 0.40 parts of tetraisopropyl titanate as a catalyst were once placed in a reaction vessel, stirred in a nitrogen gas stream, and a reflux condenser was installed. While the excess unit alcohol is refluxed, heating is continued in the range of 130 to 250 ° C until the acid value becomes 2 or less, and the generated water is continuously removed. Then, the distillate portion was removed under reduced pressure of 1.33 × 10 ⁴ Pa to finally 4 × 10 ² Pa in the range of 200 to 230 ° C, and then filtered to obtain an aromatic terminal ester-based plasticizer having the following properties.

Viscosity (25 ° C, mPa.s); 43400

Acid value; 0.2

<Sample No. 2 (aromatic terminal ester sample)>

The same as Sample No. 1 except that 410 parts of phthalic acid, 610 parts of benzoic acid, 341 parts of ethylene glycol, and 0.35 parts of tetraisopropyl titanate as a catalyst were charged in the reaction vessel. An aromatic terminal ester having the following properties.

Viscosity (25 ° C, nPa.s); 31000

Acid value; 0.1

<Sample No. 3 (aromatic terminal ester sample)>

The same as sample No. 1 except that 410 parts of phthalic acid, 610 parts of benzoic acid, 418 parts of 1,2-propanediol, and 0.35 parts of tetraisopropyl titanate as a catalyst were charged in the reaction vessel. An aromatic terminal ester having the following properties was obtained.

Viscosity (25 ° C, mPa.s); 38000

Acid value; 0.05

<Sample No. 4 (aromatic terminal ester sample)>

In addition to the injection of 410 parts of phthalic acid in the reaction vessel, benzoic acid An aromatic terminal ester having the following properties was obtained in the same manner as in the sample No. 1 except for 610 parts, 418 parts of 1,3-propanediol, and 0.35 parts of tetraisopropyl titanate as a catalyst.

Viscosity (25 ° C, mPa.s); 37000

Acid value; 0.05

Specific examples of the aromatic terminal ester-based plasticizer are shown below, but the present invention is not limited thereto.

The stretched cellulose ester film of the present invention is preferably in the range of 1 to 20% by mass, particularly preferably in the range of 3 to 11% by mass, and contains the above polyester compound in the stretched cellulose ester film. . When it is in this range, the excellent effects of the present invention can be exhibited, and failure such as breakage can be suppressed.

(UV absorber)

The stretched cellulose ester film of the present invention may also contain an ultraviolet absorber. For the purpose of improving the durability by absorbing ultraviolet rays of 400 nm or less, the ultraviolet ray absorbing agent preferably has a transmittance of 10% or less, more preferably 5% or less, and still more preferably 2% or less.

The ultraviolet absorber used in the present invention is not particularly limited, and examples thereof include an oxydiphenyl ketone compound, a benzotriazole compound, a salicylate compound, a diphenyl ketone compound, and a cyanoacrylate system. A compound, a triazine-based compound, a nickel complex compound, an inorganic powder or the like.

For example, 5-chloro-2-(3,5-di-secondary butyl-2-hydroxyphenyl)-2H-benzotriazole, (2-2H-benzotriazol-2-yl)-6 - (linear or side chain dodecyl)-4-methylphenol, 2-hydroxy-4-benzyloxydiphenyl ketone, 2,4-benzyloxydiphenyl ketone, etc., in addition, there is Tinuvin 109, Tinuvin, such as Tinuvin 171, Tinuvin 234, Tinuvin 326, Tinuvin 327, Tinuvin 328, etc., are commercially available from BASF Japan Co., Ltd., and can be preferably used.

The ultraviolet absorber which can be preferably used in the present invention is a benzotriazole-based ultraviolet absorber, a diphenylketone-based ultraviolet absorber, a triazine-based ultraviolet absorber, and particularly preferably a benzotriazole-based ultraviolet absorber. , Diphenyl ketone UV absorber.

Specific examples of the benzotriazole-based ultraviolet absorber used in the present invention are shown in the following series, but the present invention is not limited thereto.

UV-1: 2-(2'-hydroxy-5'-methylphenyl)benzotriazole

UV-2: 2-(2'-hydroxy-3',5'-di-tertiary butylphenyl)benzotriazole

UV-3: 2-(2'-hydroxy-3'-tertiarybutyl-5'-methylphenyl)benzotriazole

UV-4: 2-(2'-hydroxy-3',5'-di-tertiary butylphenyl)-5-chlorobenzotriazole

UV-5: 2-(2'-hydroxy-3'-(3",4",5",6"-tetrahydrophthalimidomethyl)-5'-methylphenyl)benzene Triazole

UV-6: 2,2-methylenebis(4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazol-2-yl)phenol)

UV-7: 2-(2'-hydroxy-3'-tertiary butyl-5'-methylphenyl)-5-chlorobenzotriazole

UV-8: 2-(2H-benzotriazol-2-yl)-6-(linear and side chain dodecyl)-4-methylphenol (TINUVIN 171)

UV-9: Octyl-3-[3-tert-butyl-4-hydroxy-5-(chloro-2H-benzotriazol-2-yl)phenyl]propionate and 2-ethylhexyl- Mixture of 3-[3-tertiary butyl-4-hydroxy-5-(5-chloro-2H-benzotriazol-2-yl)phenyl]propionate (TINUVIN 109)

Specific examples of the diphenylketone-based ultraviolet absorber used in the present invention are shown in the following series, but the present invention is not limited thereto.

UV-10: 2,4-dihydroxydiphenyl ketone

UV-11: 2,2'-dihydroxy-4-methoxydiphenyl ketone

UV-12: 2-hydroxy-4-methoxy-5-sulfonyldiphenyl ketone

UV-13: bis(2-methoxy-4-hydroxy-5-benzylidenephenylmethane).

Other, a discotic compound having a compound of 1,3,5-triazine ring or the like can also be preferably used as the ultraviolet absorber.

The stretched cellulose ester film of the present invention may contain two or more kinds of ultraviolet absorbers.

Further, the polymer ultraviolet absorber can be preferably used as an ultraviolet absorber, and in particular, a polymer type ultraviolet absorber described in JP-A-6-148430, which can be preferably used.

The ultraviolet absorber may be dissolved in an alcohol such as methanol, ethanol or butanol or an organic solvent such as dichloromethane, methyl acetate, acetone or dioxolane or a mixed solvent thereof. It is then added to the coating or added directly to the coating composition. If it is not dissolved in an organic solvent like an inorganic powder, it can be dispersed in an organic solvent and a stretched cellulose ester using a dissolver or a sand mill, and then added to the coating.

The amount of the ultraviolet absorber varies depending on the type of the ultraviolet absorber or the use conditions, and when the dried film thickness of the stretched cellulose ester film is 30 to 200 μm, it is preferably 0.5 to the total mass of the film. 10% by mass, more preferably 0.6 to 4% by mass.

(particle)

The stretched cellulose ester film of the present invention is preferred from the viewpoint of adjusting the arithmetic mean roughness (Ra) and improving the smoothness to eliminate handling defects such as hooking.

Examples of the fine particles, as the inorganic compound, include ceria, titania, alumina, zirconia, calcium carbonate, calcium carbonate, talc, clay, sintered kaolin, sintered calcium citrate, calcium citrate hydrate, and aluminum citrate. Magnesium citrate and calcium phosphate. Particles contain sputum, from the point of view of reducing turbidity More preferably, it is preferably cerium oxide.

The primary average particle diameter of the fine particles is preferably in the range of 5 to 400 nm, more preferably in the range of 10 to 300 nm. These fine particles may be contained in the secondary aggregates having a particle diameter mainly in the range of 0.05 to 0.3 μm, and may be contained as a primary particle as long as the particles have an average particle diameter in the range of 100 to 400 nm. The content of such fine particles in the stretched cellulose ester film is preferably in the range of 0.01 to 1% by mass, particularly preferably in the range of 0.05 to 0.5% by mass. In the case of a stretched cellulose ester film composed of a plurality of layers formed by a co-fluid casting method, it is preferred to contain the added amount of particles on the surface.

As the fine particles of cerium oxide, for example, those sold under the trade names of Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (above, Nippon Aerosil Co., Ltd.) can be used.

As the fine particles of zirconia, for example, those sold under the trade names of Aerosil R976 and R811 (above, Nippon Aerosil Co., Ltd.) can be used.

Examples of the polymer include a polyoxyalkylene resin, a fluororesin, and an acrylic resin. Preferably, it is a polyoxyalkylene resin, particularly preferably a three-dimensional network structure, for example, Tospearl 103, the same 105, the same 108, the same 120, the same 145, the same 3120 and the same 240 (the above is limited by Toshiba Silicone) The company name is the seller of the product name.

Among them, Aerosil 200V and Aerosil R972V maintain the lower haze of the stretched cellulose ester film and reduce the friction coefficient, so Particularly good to use. In the stretched cellulose ester film of the present invention, the dynamic friction coefficient of at least one of the faces is preferably in the range of 0.2 to 1.0.

(dye)

In the stretched cellulose ester film of the present invention, a dye for color tone adjustment may also be added. For example, in order to suppress the yellow tone of the film, a blue dye may be added. Preferred dyes include lanthanide dyes.

The lanthanide dye may have any substituent at any position from the 1st to the 8th position of the oxime. Preferred substituents include an anilino group, a hydroxyl group, an amine group, a nitro group, or a hydrogen atom. It is preferable to contain the blue dye described in JP-A-2001-154017, and particularly preferably an anthraquinone dye.

Various additives may be added in portions to the coating containing the cellulose ester solution before film formation, or may be continuously added by separately preparing an additive solution. In particular, in order to reduce the load on the filter material, it is preferred that the particles are continuously added in part or all of them.

When the additive solution is continuously added, it is preferably dissolved in a small amount of cellulose ester in order to improve the miscibility with the coating. The amount of the cellulose ester is preferably in the range of 1 to 10 parts by mass, more preferably 3 to 5 parts by mass, per 100 parts by mass of the solvent.

In the present invention, in order to continuously add and mix, for example, a continuous blender such as a static blender (manufactured by Toray Engineering Co., Ltd.) or a SWJ (Toray static in-line mixer Hi-Mixer) can be preferably used. .

<Method for Producing Stretched Cellulose Ester Film>

Next, the method for producing the drawn cellulose ester film of the present invention will be described with respect to the steps of performing flow rate control in accordance with the above extrusion die and steps other than the stretching treatment step.

The stretched cellulose ester film of the present invention may be a film produced by a solution fluid casting method or a film produced by a molten fluid casting method, and any of them may be preferably used.

The stretched cellulose ester film of the present invention produced by the solution fluid casting method is a step of preparing a coating by dissolving a cellulose ester and the aforementioned additive in a solvent; casting the coating fluid in a continuous process a step on the endless metal support; a step of drying the fluid cast film into a film; a step of peeling from the metal support; a step of stretching or width maintaining; a step of further drying; and a winding The step of completing the film is carried out.

First, the steps of preparing the coating will be described. The concentration of the cellulose ester in the coating is relatively high, so that the drying load can be reduced after the fluid is cast on the metal support, so it is preferable, but when the concentration of the cellulose ester is too rich, the load during filtration is increased, resulting in an increase in the load during filtration. The filtering accuracy deteriorates. The concentration of both may be considered at the same time, preferably from 10 to 35 mass%, more preferably from 15 to 25 mass%.

The solvent to be used in the preparation of the coating material may be used singly or in combination of two or more kinds, and a good solvent and a poor solvent of the cellulose ester may be used in combination, and it is preferable from the viewpoint of production efficiency, and the fiber is more excellent. From the viewpoint of solubility of the ester, it is preferred. A preferred range of the mixing ratio of the good solvent to the poor solvent, the good solvent is 70 to 98% by mass, and the poor solvent is 2 to 30. the amount%. A good solvent or a poor solvent is defined as a good solvent in which the cellulose ester to be used alone is dissolved, and a case in which swelling or insolubilization occurs when used alone is defined as a poor solvent. Therefore, the good solvent and the poor solvent differ depending on the average degree of acetylation of the cellulose ester (the degree of substitution of the acetyl group), for example, when acetone is used as the solvent, the acetate in the cellulose ester ( Ethyl thiol substitution degree 2.4), cellulose acetate propionate is a good solvent, and it is a poor solvent in cellulose acetate (acetylation degree 2.8).

The good solvent is not particularly limited, and examples thereof include organic halides such as dichloromethane, dioxolane, acetone, methyl acetate, and ethyl acetate. Particularly preferred are dichloromethane or methyl acetate.

Further, the poor solvent is not particularly limited, and for example, methanol, ethanol, n-butanol, cyclohexane, cyclohexanone or the like can be preferably used. Further, in the coating material, it is preferred to contain 0.01 to 2% by mass of water. Further, the solvent used for the dissolution of the cellulose ester can be recovered and reused by removing the solvent which is removed from the film by the drying in the film forming step of the film. In the recovery solvent, an additive added to the cellulose ester, such as a plasticizer, an ultraviolet absorber, a polymer, a monomer component, or the like may be contained in a trace amount, but even if it is contained, it may be preferably reused, or It can be refined for reuse as necessary.

A general method can be used for the method of dissolving the cellulose ester in the preparation of the above coating. When combined with heating and pressurization, it can be heated to above the boiling point at normal pressure. When the solvent is stirred and dissolved while being heated at a temperature higher than the boiling point of the normal pressure and not boiling under pressure, it is possible to prevent the occurrence of gel or a mass of undissolved matter called a small piece. Preferably. In addition, it is preferred to mix the cellulose ester with a poor solvent to wet or swell it, and then A method of adding a good solvent to dissolve it.

The pressurization can be carried out by a method in which an inert gas such as nitrogen is introduced, or a method in which the vapor pressure of the solvent is raised by heating. The heating is preferably carried out from the outside. For example, the jacket type can be easily controlled by temperature, which is preferable.

The heating temperature at the time of adding a solvent is preferable from the viewpoint of the solubility of the cellulose ester. However, when the heating temperature is too high, the required pressure is increased to deteriorate the productivity. The preferred heating temperature is in the range of 45 to 120 ° C, particularly preferably in the range of 60 to 110 ° C, more preferably in the range of 70 to 105 ° C. In addition, the pressure can be adjusted at a set temperature so that the solvent does not boil.

Alternatively, a cooling dissolution method can be preferably used, whereby the cellulose ester can be dissolved in a solvent such as methyl acetate.

The cellulose ester solution is then filtered using a suitable filter material such as filter paper. In order to remove insoluble matter or the like, the filter material is preferably as small as possible, but when the absolute filtration accuracy is too small, there is a problem that the filter material is likely to be clogged. Therefore, a filter material having an absolute filtration accuracy of 0.008 mm or less is preferable, and a filter material in the range of 0.001 to 0.008 mm is preferable, and a filter material in the range of 0.003 to 0.006 mm is more preferable.

The material of the filter material is not particularly limited, and a general filter medium, a filter material made of plastic such as polypropylene or Teflon (registered trademark), or a filter material made of metal such as stainless steel can be used, and it is preferable that the fiber does not fall off. Preferably, the impurities contained in the cellulose ester of the raw material, especially bright spot impurities, are removed or reduced by filtration.

The bright spot impurity refers to a state in which two polarizing plates are arranged in a crossed polarization state, and a stretched cellulose ester film is disposed therebetween, and light is irradiated from one side of one of the polarizing plates and viewed from one side of the other polarizing plate. , can be seen from the opposite side of the point of light leakage (foreign matter) were to a diameter of 0.01mm or more highlights number of 200 / cm ² or less is preferred, 100 / cm ² or less are preferred, ² or less 50 / cm Better. 0~10/cm ² or less is especially good. In addition, the fewer the bright spots below 0.01 mm, the better.

The filtration of the coating material can be carried out by a general method, but the method of filtering while heating in a temperature range of a solvent above a boiling point at normal pressure and not boiling under pressure, and a filtration pressure difference before and after filtration ( It is preferable that the rise of the differential pressure is small. The preferred temperature is in the range of 45 to 120 ° C, particularly preferably in the range of 45 to 70 ° C, more preferably in the range of 45 to 55 ° C.

The smaller the filter pressure, the better. The filtration pressure is preferably 1.6 MPa or less, more preferably 1.2 MPa or less, still more preferably 1.0 MPa or less.

The fluid cast film of the coating is described herein.

The metal support used in the fluid casting (casting) step is preferably a mirror-finished surface, a metal support, preferably a stainless steel strip or a cast and a surface-plated cylinder. The width of the cast film can be set to 1~4m. The surface temperature of the metal support in the fluid casting step, in the temperature of -50 ° C ~ the boiling point of the solvent, the higher the temperature, the faster the drying speed of the film, so it is better, but when the temperature is too high, Sometimes there is a case where the film is foamed or the flatness is deteriorated. The preferred support temperature is in the range of 0 to 40 ° C, more preferably in the range of 5 to 30 ° C. Alternatively, in the state where a large amount of residual solvent is contained by gelation of the membrane by cooling A peeling method in the drum is also a preferred method. The method of controlling the temperature of the metal support is not particularly limited, and there is a method of blowing hot air or cold air, or a method of bringing warm water into contact with the inner side of the metal support. In the case of using warm water, heat transfer can be efficiently performed, and the temperature of the metal support is shortened to a certain temperature, which is preferable. When hot air is used, it is sometimes used at a higher temperature than the target temperature.

In order to exhibit good planarity of the stretched cellulose ester film, the amount of residual solvent when the film is peeled off from the metal support is preferably in the range of 10 to 150% by mass, more preferably 20 to 40% by mass. Within the range of % or 60 to 130% by mass, it is particularly preferably in the range of 20 to 30% by mass or 70 to 120% by mass.

In the present invention, the amount of residual solvent is defined by the following formula.

Residual solvent amount (% by mass) = {(M - N) / N} × 100

In the formula, M represents the mass of a sample for collecting a film or a film at any time during or after the production, and N represents the mass after heating M at 115 ° C for 1 hour.

Next, the peeled film is conveyed to the above-mentioned stretching treatment step (preferably a tenter) to carry out the stretching treatment of the present invention, and is carried as a stretched cellulose ester film to a film drying step.

In the film drying step, the amount of the residual solvent is preferably 1% by mass or less, more preferably 0.1% by mass or less, and particularly preferably 0% to 0.01% by mass or less.

In the film drying step, generally, a method in which the film is dried while conveying the film by a roll drying method (the film is alternately dried by a plurality of rolls disposed above and below) or a tenter method is used.

The means for drying the membrane is not particularly limited, and examples thereof include hot air, infrared rays, heating rolls, microwaves, and the like, and from the viewpoint of simplicity, it is preferably carried out by hot air.

The drying temperature in the film drying step is preferably in the range of 90 to 200 ° C, particularly preferably in the range of 110 to 160 ° C. The drying temperature is preferably increased stepwise.

The preferred drying time varies depending on the drying temperature, but is preferably in the range of 5 to 60 minutes, and particularly preferably in the range of 10 to 30 minutes.

The film thickness of the stretched cellulose ester film is not particularly limited, but is preferably in the range of 10 to 200 μm, particularly preferably in the range of 10 to 100 μm, and more preferably 30 to 30% from the viewpoint of film formation and weight reduction. Within the range of 70 μm.

The stretched cellulose ester film of the present invention is in the range of 2 to 4 m in width, and more preferably in the range of 2 to 3 m. When it exceeds 4 m, it becomes difficult to carry.

The stretched cellulose ester film is preferably thermally fixed and thermally fixed after the stretching treatment, preferably in a temperature range of from Tg to 20 ° C, and usually in the range of from 0.5 to 300 seconds. Heat fixed. In this case, it is preferable to heat-fix while gradually increasing the temperature in a range in which the temperature difference is in the range of 1 to 100 ° C in a region divided into two or more.

Heat-fixed film, usually cooled to below Tg, and cut thin The slap grips at both ends of the membrane are taken up for winding. Cooling is preferably carried out slowly from the final heat setting temperature to Tg at a cooling rate of 100 ° C or less per second. The means for cooling and relaxation treatment is not particularly limited, and it can be carried out by a conventional means known in the art. However, from the viewpoint of improving the dimensional stability of the film, it is particularly preferable to successively cool the plurality of temperature regions. Perform such processing.

The more suitable conditions for such heat-fixing conditions, cooling, and relaxation treatment conditions are different depending on the type of the additive such as the cellulose ester or the plasticizer constituting the film, so that the physical properties of the obtained stretched film can be measured and appropriately The ground is adjusted to have better characteristics to determine.

When the slow axis or the fast axis of the stretched cellulose ester film of the present invention is present in the film plane, and the angle formed with the film forming direction is θ 1 , θ 1 is preferably -1° or more and +1°. Hereinafter, it is particularly preferably -0.5 or more and +0.5 or less. The θ 1 can be defined as the alignment angle, and the measurement of θ 1 can be performed using an automatic refractometer KOBRA-21ADH (manufactured by Oji Scientific Instruments Co., Ltd.). θ 1 satisfies the above-mentioned relationships, and is advantageous in obtaining a high luminance in the display image and suppressing or preventing light leakage, and is advantageous in obtaining a faithful color reproduction in a color liquid crystal display device.

<physical property> (refractive index control)

The stretched cellulose ester film of the present invention is also an important operation for adjusting the retardation by stretching. In the stretched cellulose ester film of the present invention, the retardation value Ro in the in-plane direction represented by the following formula is preferably in the range of 0 to 20 nm. The retardation value Rt in the thickness direction is preferably in the range of -100 to 100 nm, and more preferably in the range of Ro ≦ 5 nm, -30 nm ≦ Rt ≦ 30 nm.

In addition, it is preferable to increase the retardation value by the stretching treatment as the retardation film. In this case, the retardation value Ro in the in-plane direction is preferably in the range of 30 to 100 nm, and the retardation in the thickness direction. The value Rt is preferably in the range of 70 to 400 nm.

Formula (i)Ro=(n _x -n _y )×d

Formula (ii) Rt = ((n _x + n _y ) / 2 - n _z ) × d (wherein n _x represents the refractive index in the slow axis direction of the film, and n _y represents the fast axis in the plane of the film The refractive index in the direction, n _z represents the refractive index in the thickness direction of the film, and d represents the thickness (nm) of the film)

The refractive index can be determined, for example, by using KOBRA-WR (manufactured by Oji Scientific Instruments Co., Ltd.) at a wavelength of 590 nm in an environment of 23 ° C and 55% RH.

(other physical properties)

The moisture permeability of the stretched cellulose ester film of the present invention is preferably from 10 to 1200 g/m ² at 40 ° C and 90% RH . In the range of 24h, it is more preferably 20~1000g/m ² . Within the range of 24h, it is particularly good at 20~850g/m ² . Within the range of 24h. The moisture permeability can be measured in accordance with the method described in JIS Z 0208.

The visible light transmittance of the stretched cellulose ester film of the present invention is preferably 90% or more, more preferably 93% or more.

The haze of the stretched cellulose ester film of the present invention is preferably in the range of less than 1%, more preferably 0 to 0.1%.

<Polarizing plate>

Next, a polarizing plate using the stretched cellulose ester film of the present invention, and a liquid crystal display device using the polarizing plate will be described.

In the polarizing plate, the stretched cellulose ester film of the present invention is bonded to at least one surface of a polarizing element.

The polarizing plate can be produced by a general method. Preferably, the polarizing element side of the stretched cellulose ester film of the present invention is subjected to an alkali saponification treatment, and at least one surface of the polarizing element produced by stretching in an iodine solution is used, and a completely saponified polyethylene is used. An aqueous alcohol solution is applied. On the other side, the stretched cellulose ester film or other optical film can be used. Commercially available cellulose ester films (e.g., Konica Minolta Tac KC8UX, KC4UX, KC5UX, KC8UY, KC4UY, KC12UR, KC8UCR-3, KC8UCR-4, KC8UCR-5, KC4FR-1, KC8UY-HA, KC8UX) can be preferably used. -RHA, KC4UA, KC6UA, the above is made by Konica Minolta Advanced Layers Co., Ltd.).

For example, when the stretched cellulose ester film of the present invention has a retardation value Ro in the in-plane direction in the range of 0 to 20 nm and a retardation value Rt in the thickness direction in the range of -100 to 100 nm, the intermediate liquid crystal cell Further, the optical film of the polarizing plate used on the opposite side preferably has a retardation value Ro in the in-plane direction measured at a wavelength of 590 nm in a range of 20 to 100 nm, and a retardation value Rt in a thickness direction at 70 to 70. An optical film with a phase difference function in the range of 300 nm.

The optical film having the above-described phase difference function is not particularly limited, for example, It can be produced by the method described in JP-A-2005-196149 and JP-A-2005-275104. Further, it is preferable to use an optical film having an optical compensation film having a liquid crystal compound such as a discotic liquid crystal or the like which is aligned to the formed optical anisotropic layer. The optically anisotropic layer can be formed, for example, by the method described in JP-A-2005-275083. By using an optical film having the above-described phase difference function in combination, a polarizing plate and a liquid crystal display device having a stable viewing angle expansion effect can be obtained.

The polarizing element which is a main component of a polarizing plate is an element which passes only the light of a polarizing surface in a certain direction, and a typical polarizing element currently known is a polyvinyl alcohol type polarizing film, and this is the iodine dyed in polyethylene. Those who have an alcohol-based film and those who dye a dichroic dye to a polyvinyl alcohol-based film. The polarizing element is formed by forming a film of a polyvinyl alcohol aqueous solution, uniaxially stretching and dyeing it, or uniaxially stretching after dyeing, and it is preferred to use a boron compound for durability treatment. The film thickness of the polarizing element is preferably in the range of 5 to 30 μm, particularly preferably in the range of 10 to 20 μm.

In addition, the range of the ethylene unit content of 1 to 4 mol% and the polymerization degree of 2000 to 4000 described in JP-A-2003-248232, JP-A-2003-342322, and the like can be preferably used. An ethylene-modified polyvinyl alcohol film having a degree of saponification in the range of 99.0 to 99.99 mol%. Among them, an ethylene-modified polyvinyl alcohol film having a hot water cut-off temperature of 66 to 73 ° C can be preferably used. Further, in the case where the difference in hot water cut temperature between the two points at a distance of 5 cm in the TD direction of the film is 1 ° C or less, the color unevenness can be lowered, and more preferably, the distance in the TD direction of the film is further It is more preferable that the difference in hot water cut temperature between two points of 1 cm is 0.5 ° C or less to reduce the color unevenness.

The polarizing element using the ethylene-modified polyvinyl alcohol film is excellent in polarizing performance and durability, and has few color spots, and can be particularly preferably used in a large liquid crystal display device.

The polarizing element obtained in the above manner is generally used as a polarizing plate in which a protective film is bonded to both surfaces or a single surface, and an adhesive used for bonding may, for example, be a PVA adhesive or a urethane. It is preferably an adhesive or the like, and a PVA-based adhesive is preferably used.

<Liquid crystal display device>

By assembling the polarizing plate to the display device, various liquid crystal display devices having excellent visibility can be produced. The liquid crystal display device can be preferably applied to a reflective, transmissive or semi-transmissive liquid crystal display device, or a liquid crystal of various driving methods such as TN type, STN type, OCB type, VA type, IPS type, ECB type, or the like. The display device is particularly preferably a VA type (MVA type, PVA type) liquid crystal display device.

In the stretched cellulose ester film of the present invention, since the retardation value Ro of the in-plane direction is small in the width direction, the polarizing plate is used, and the viewing property is good even when used in a large-screen liquid crystal display device. Provides excellent frontal contrast.

In the large-screen liquid crystal display device in which the screen is 17-inch or more, in particular, the large-screen liquid crystal display device having a screen size of 30 以上 or more does not cause color fluctuation or wave fluctuation, and therefore has an effect of not causing eye fatigue even if it is viewed for a long period of time.

[Examples]

The invention is specifically described by the following examples, but the invention is not limited thereto.

Example 1 <Production of Stretched Cellulose Ester Film 1> (Particle dispersion 1)

The ingredients were stirred in a dissolver for 50 minutes, and then dispersed by a Manton-Gaulin homogenizer.

(Particle Additive 1)

The fine particle dispersion 1 was slowly added while sufficiently stirring the dissolution tank into which methylene chloride was introduced. Further, the dispersion was carried out by a grinder so that the particle diameter of the secondary particles became a predetermined size. This was filtered by a wire NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle addition liquid 1.

The main composition of the following composition was prepared. First, dichloromethane and ethanol were added to the pressurized dissolution tank. Stirring in a pressurized dissolution tank filled with solvent The deuterated cellulose with a degree of substitution of 2.60 was introduced. This was heated and stirred to completely dissolve. The main paint was prepared by filtration using Angstrom filter paper No. 244 manufactured by Anchip Paper Co., Ltd.

(composition of the main paint)

The above components were placed in a closed container, stirred and dissolved to prepare a coating material. Next, a fluid casting film was cast on the stainless steel belt support at a temperature of 33 ° C and a uniform film thickness at a temperature of 33 ° C at a width of 1600 mm. The temperature of the stainless steel belt is controlled at 30 °C.

On the stainless steel belt support, the amount of residual solvent in the film after evaporating the solvent to the fluid casting film (casting) was 75%, and then peeled off from the stainless steel belt support at a peeling tension of 130 N/m.

After the peeling of the deuterated cellulose film, the temperature of the outer cover 10 was adjusted using a tenter shown in Fig. 3, and the stretching temperature of the surface of the film was adjusted to 170 ° C, and the stretching ratio was 35%. In the width direction Line stretching.

The surface temperature of the film end portion and the center portion is measured by using a contact type hand-held thermometer (ANRITSU DIGITAL THERMOMETER HA-100K) in the width direction of the film to be conveyed, and the average value is used as the portion. surface temperature.

Next, in the drying zone, high speed conveyance is performed by a plurality of rolls, and drying is completed, and the end portion is cut and then wound up so as to become a desired product width. The drying temperature was 130 ° C and the handling tension was 100 N/m.

As described above, a stretched cellulose ester film 1 having a film width of 1490 mm, a dry film thickness of 60 μm at the film end, and a length of 5000 m was produced.

Using a contact type film thickness meter (manufactured by Tokyo Seimitsu Co., Ltd.: Micrometer Minicom M), the film thickness of the stretched cellulose ester film 1 after processing was measured at intervals of 10 cm from the end portion in the width direction, from which the value was obtained. The film thickness difference h (maximum film thickness - end film thickness) was determined and found to be 0.5 μm. Further, by the regression equation, it is determined from the above-mentioned film thickness measurement value whether or not it can be represented by a catenary curve, and as a result, it cannot be represented by a catenary curve.

<Production of Stretched Cellulose Ester Film 2>

In the production of the stretched cellulose ester film 1, a fluid is cast on a stainless steel belt support at a temperature of 33 ° C at a width of 2400 mm so that the coating material has a uniform film thickness, and the width of the processed film is set to 2300 mm. Except for this, the stretched cellulose ester film 2 was produced in the same manner.

Using a contact type film thickness meter (manufactured by Tokyo Precision Co., Ltd.: Micrometer Minicom M), the end portion was measured at an interval of 10 cm in the width direction. The film thickness of the stretched cellulose ester film 1 after the processing was determined, and the film thickness difference h (maximum film thickness - end film thickness) was determined from this value and found to be 0.5 μm. Further, by the regression equation, it is determined from the above-mentioned film thickness measurement value whether or not it can be represented by a catenary curve, and as a result, it cannot be represented by a catenary curve.

<Production of Stretched Cellulose Ester Film 3>

In the production of the stretched cellulose ester film 2, when the coating fluid is cast on the stainless steel belt support by the slit gap of the nozzle of the extrusion die, the central portion is formed such that the film thickness approximates the catenary curve. A stretched cellulose ester film 3 was produced in the same manner except that the end portion was thicker to carry out a fluid casting film.

Using a contact type film thickness meter (manufactured by Tokyo Seimitsu Co., Ltd.: Micrometer Minicom M), the film thickness of the stretched cellulose ester film 3 after the processing was measured and measured at intervals of 10 cm from the end portion in the width direction, from which the value was obtained. The film thickness difference h (maximum film thickness - end film thickness) was determined and found to be 1.5 μm. Further, by the regression equation, it is judged from the above-mentioned film thickness measurement value whether or not it can be represented by a catenary curve, and the result can be represented by a catenary curve.

<Production of Stretched Cellulose Ester Film 4>

Change the composition of the main paint as follows.

(composition of the main paint)

Similar to the production of the stretched cellulose ester film 3, when the coating fluid is cast on the stainless steel belt support by the slit gap of the nozzle of the extrusion die, the central portion is made such that the film thickness approximates the catenary curve. A thicker end portion was formed to carry out a fluid casting film, and a stretched cellulose ester film 4 was produced under the conditions of the second table.

Using a contact type film thickness meter (manufactured by Tokyo Seimitsu Co., Ltd.: Micrometer Minicom M), the film thickness of the stretched cellulose ester film 4 after the processing was measured and measured at intervals of 10 cm from the end portion in the width direction, from which the value was obtained. The film thickness difference h (maximum film thickness - end film thickness) was determined and found to be 1.5 μm. Further, by the regression equation, it is judged from the above-mentioned film thickness measurement value whether or not it can be represented by a catenary curve, and the result can be represented by a catenary curve.

<Production of Stretched Cellulose Ester Films 5 and 6>

In the production of the stretched cellulose ester film 4, the film thickness of the center portion and the end portion is adjusted by changing the slit gap of the nozzle of the extrusion die so as to be the condition described in the second table. The stretched cellulose ester films 5 and 6 were produced in the same manner.

Using a contact type film thickness meter (manufactured by Tokyo Seimitsu Co., Ltd.: Micrometer Minicom M), the film thickness of the stretched cellulose ester films 5 and 6 after processing was measured at intervals of 10 cm from the end portion in the width direction. The film thickness difference h (maximum film thickness - end film thickness) was obtained from the values, and the results are as shown in Table 2. Further, by the regression equation, it is judged from the above-mentioned film thickness measurement value whether or not it can be represented by a catenary curve, and the result can be represented by a catenary curve.

<Production of Stretched Cellulose Ester Film 7>

In the production of the stretched cellulose ester film 4, the tenter shown in Fig. 2 is used to adjust the temperature of the outer cover 10 to the stretched temperature of the unstretched cellulose film after peeling. The temperature was changed to 170 ° C, and then the end cold air generating portion G1 was placed at the position shown in FIG. 5 so that the temperature of the film surface was adjusted to 155 ° C while the temperature was adjusted, and the width was 45%. The stretching was carried out to produce a stretched cellulose ester film 7.

Using a contact type film thickness meter (manufactured by Tokyo Seimitsu Co., Ltd.: Micrometer Minicom M), the film thickness of the stretched cellulose ester film 7 after processing was measured and measured at an interval of 10 cm from the end portion in the width direction, from which the value was obtained. The film thickness difference h (maximum film thickness - end film thickness) was obtained, and the results are as shown in Table 2. Further, by the regression equation, it is judged from the above-mentioned film thickness measurement value whether or not it can be represented by a catenary curve, and the result can be represented by a catenary curve.

<Production of stretched cellulose ester film 8~12>

In the preparation of the stretched cellulose ester film 7, the ethyl ester group of the cellulose ester The stretched cellulose ester films 8 to 12 were produced in the same manner except that the degree of substitution, the maximum film thickness of the film, the film thickness at the end of the film, the processing width, and the stretching temperature were changed as shown in Table 2.

Using a contact type film thickness meter (manufactured by Tokyo Seimitsu Co., Ltd.: Micrometer Minicom M), the film thickness of the stretched cellulose ester film 8 to 12 after the processing was measured and measured at intervals of 10 cm from the end portion in the width direction. The film thickness difference h (maximum film thickness - end film thickness) was obtained from the values, and the results are as shown in Table 2. Further, by the regression equation, it is judged from the above-mentioned film thickness measurement value whether or not it can be represented by a catenary curve, and the result can be represented by a catenary curve.

<Production of Stretched Cellulose Ester Film 13>

In the production of the stretched cellulose ester film 9, the end portion cold air generating portion G1 shown in Fig. 5 is provided only at the center portion, and the temperature at the center portion is stretched by 30 ° C lower than the end portion, and the stretching is performed. Further, the stretched cellulose ester film 13 was produced in the same manner.

Using a contact type film thickness meter (manufactured by Tokyo Seimitsu Co., Ltd.: Micrometer Minicom M), the film thickness of the stretched cellulose ester film 13 after processing was measured at intervals of 10 cm from the end portion in the width direction, from which the value was obtained. The film thickness difference h (maximum film thickness - end film thickness) was determined and found to be 5.3 μm. Further, by the regression equation, it is determined from the above-mentioned film thickness measurement value whether or not it can be represented by a catenary curve, and as a result, it cannot be represented by a catenary curve.

Evaluation

For the stretched cellulose ester film 1~13 produced, the following evaluations were carried out. estimate.

(Measurement of arithmetic mean roughness (Ra))

The average value of the arithmetic mean roughness (Ra) of the end portion is selected from the film end portion (the range H in Fig. 3) by 10 points in the longitudinal direction, and the arithmetic mean roughness (Ra) is measured and the average is obtained. value.

The average value of the arithmetic mean roughness (Ra) of the center portion is 10 points in the longitudinal direction with respect to the center portion (range T in Fig. 3), and the arithmetic mean roughness (Ra) is measured and the average value is obtained. .

The arithmetic mean roughness (Ra) was measured in accordance with JIS B 0601 using a non-contact surface fine shape measuring device WYKO HD3300.

(striping suitability at high speed handling)

The sliver suitability at the time of high-speed conveyance was evaluated by the following criteria at a high speed condition of a conveyance speed of 1.3 times the film conveyance speed in the reference condition.

◎: There was no problem of trimming at all during high-speed handling.

○: There is almost no edge trimming during high-speed conveyance.

△: Frequent edge trimming occurs frequently during high-speed conveyance.

×: Frequent edge trimming occurs frequently during high-speed conveyance and breakage occurs.

The practical allowable range is ○ or more.

(Ro change)

From the end of the produced stretched cellulose ester film and the central part A sample of 10 samples was used, and the retardation value Ro in the in-plane direction at a wavelength of 590 nm was measured using a KOBRA-WR (manufactured by Oji Scientific Instruments Co., Ltd.) at 23 ° C and 55% RH, and the center was respectively obtained. The average value of the block value Ro of the part and the end. The difference is then evaluated by the following benchmarks.

Formula (i) Ro = (n _{x -} n _y ) × d (wherein n _x represents the refractive index in the slow axis direction in the plane of the film, and n _y represents the refractive index in the fast axis direction in the plane of the film, d Indicates the thickness (nm) of the film)

A: (central-end) difference is less than 0.5nm

B: (center-end) difference is 0.5 nm or more and less than 1.0 nm

C: (center portion - end portion) has a difference of 1.0 nm or more and less than 2.0 nm

D: (center-end) difference is 2.0 nm or more

The practical allowable range is B or more.

The composition and evaluation results of the above-mentioned stretched cellulose ester film are shown in Tables 2 and 3.

From the results of the second and third tables, it is understood that the stretched cellulose ester film of the present invention has a wide range of stretched cellulose ester film of the comparative example, and the stripe suitability at the time of high-speed conveyance It is also preferable that the variation of the retardation value Ro in the in-plane direction of the center portion and the end portion is small, so that the variation in optical characteristics is also good.

Example 2 (production of polarizing plate)

The drawn cellulose ester film 1 to 13 prepared above was subjected to alkali treatment in a 2.5 mol/L sodium hydroxide aqueous solution at 40 ° C for 60 seconds, and washed with water for 3 minutes to carry out saponification treatment to obtain an alkali-treated film.

Next, the polyvinyl alcohol film having a thickness of 120 μm is uniaxially stretched ( The temperature was 110 ° C and the stretching ratio was 5 times). This film was immersed in an aqueous solution containing 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 g of 6 g of potassium iodide, 7.5 g of boric acid, and 100 g of water. This water is then washed and dried to obtain a long strip-shaped polarizing element.

Then, the stretched cellulose ester films 1 to 13 were bonded to both sides of each of the polarizing elements by using a completely saponified polyvinyl alcohol 5% aqueous solution as an adhesive, thereby producing polarizing plates 1 to 13.

(Production of liquid crystal display device)

A liquid crystal panel for performing viewing angle measurement was produced in the following manner, and the characteristics as a liquid crystal display device were evaluated.

The polarizing plate on the viewing side which was previously bonded to the 40-type display KLV-40J3000 manufactured by SONY of the VA mode liquid crystal display device was peeled off, and the polarizing plate 1 to be produced was formed so that the absorption axes of the polarizing plates were uniform. 13 A VA mode liquid crystal display device was fabricated by laminating the glass surface of the liquid crystal cell, and the color change and front contrast were evaluated visually.

As a result, it is understood that the polarizing plate and the liquid crystal display device using the stretched cellulose ester film of the present invention have a small variation in the retardation value Ro in the in-plane direction, so that the color shift is not caused and the front surface is better. Board, liquid crystal display device.

Industrial applicability:

The stretched cellulose ester film of the present invention has a wide range of stretching even at a high rate, and can suppress the disorder of cellulose alignment even if High-speed conveyance is also less prone to trimming failure, and the retardation value Ro in the in-plane direction is small in variation of each portion of the film, so that it can be preferably applied to a polarizing plate protective film or an optical film for a liquid crystal display device.

A‧‧‧A face

B‧‧‧B

Mh‧‧‧Maximum film thickness

Lh‧‧‧ end film thickness

K‧‧‧ catenary curve

W, Fo‧‧‧Unstretched cellulose ester film (diaphragm)

F‧‧‧Stretched cellulose ester film

1‧‧‧Stainless steel circulating steel strip (support)

3‧‧‧ peeling roller

4‧‧‧ tenter

5‧‧‧Drying device

6‧‧‧Transport roller

8‧‧‧Winding roller

10‧‧‧ Cover

11‧‧‧ Picture

12‧‧‧ Track

G1, G2‧‧‧ end cold wind generating part

Fig. 1 is a schematic view showing the cross-sectional shape of the stretched cellulose ester film of the present invention.

Fig. 2 is a schematic side view showing the structure of a manufacturing apparatus for producing a stretched cellulose ester film of the present invention.

Fig. 3 is a schematic plan view of a stretching device (tenter).

Figure 4 is a schematic view of a stretched cellulose ester film of the present invention.

Figure 5 is a schematic view showing the preferred stretching treatment method of the present invention.

Claims (6)

A stretched cellulose ester film comprising a cellulose ester film of a cellulose ester having an ethyl ketone group substitution degree in the range of 2.8 to 2.95, characterized in that the width of the A side of the stretched cellulose ester film A part of the cross-sectional shape in the direction is represented by a catenary curve, and the film thickness difference h (the film maximum film thickness - the film end film thickness) is in the range of 1.0 to 4.0 μm; here, the above-mentioned A surface means that the film is coated. When the film is formed on a steel strip or a roll, the film is formed on the opposite side to the side of the steel strip surface or the drum surface. The stretched cellulose ester film of claim 1, wherein the average value of the arithmetic mean roughness (Ra) of the central portion of the surface of the stretched cellulose ester film is in the range of 2.2 to 3.5 nm, and The average value of the arithmetic mean roughness (Ra) of the end portion of the surface of the stretched cellulose ester film is 0.3 to 1.0 nm. Here, the end portion means that the full width of the stretched cellulose ester film is L. In the case of the end portion of the film to a portion of L × 0.05, the central portion means a portion having a width L of 0.1 from the central portion of the film to the width direction when the full width of the stretched cellulose ester film is L. The stretched cellulose ester film according to claim 1 or 2, wherein the stretched cellulose ester film has a width in the range of 2 to 3 m, and the maximum film thickness of the film is in the range of 30 to 70 μm. A method for producing a stretched cellulose ester film, which is produced by the stretched cellulose ester film according to any one of claims 1 to 3. The method is characterized in that the coating of the stretched cellulose ester film is formed such that a part of the cross-sectional shape in the width direction of the film A surface is fluidly cast on the steel strip or the drum by a catenary curve. After forming the film, after the peeling, the surface temperature of the end portion of the film A surface is lowered to a range of 10 to 50 ° C lower than the surface temperature of the center portion, and the stretching treatment is performed. The above-mentioned end portion means that when the full width of the unstretched cellulose ester film is Lo, it is the portion from the end of the film to Lo × 0.05, and the central portion refers to the entire unstretched cellulose ester film. When the width is Lo, the portion from the center of the film to the width direction is ±Lo × 0.1. The method for producing a stretched cellulose ester film according to claim 4, wherein at least one pair of end cold air generating portions are provided for adjusting the surface temperature of the end portion, and one side of the cold air generating portion from the end portion The cold air having a lower temperature in a range of 10 to 50 ° C lower than the temperature of the central portion is blown toward the end portion, and is subjected to a stretching treatment. The method for producing a stretched cellulose ester film according to claim 4 or 5, wherein the gas ambient temperature during the stretching treatment is in the range of 160 to 190 ° C, and is in the range of 25 to 100%. The draw ratio is stretched in the film width direction.