JP5861700B2 - Stretched cellulose ester film and method for producing the same - Google Patents

Description

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

  In recent years, the demand for liquid crystal display devices (hereinafter also referred to as LCDs) is vigorous due to the widespread use of liquid crystal displays mounted on automobiles, large liquid crystal television displays, mobile phones, notebook computers, and the like. In such LCDs, various optical films such as a polarizing film and a retardation film are used.

  The demand for LCDs is increasing, and there is a demand for thinner, lighter, and more productive polarizing plates that are used in line with this demand. Furthermore, along with the increase in the screen size of LCDs, the optical film as a member is also required to be thinned and widened with high production, and studies to improve film properties centering on mechanical strength properties are also being promoted. Yes.

Cellulose ester films are commonly used as polarizing plate protective films, but when manufacturing such thin and wide films, in order to adjust the optical properties and flatness, and the film thickness and width of the resulting film. In general, after film formation, the film is stretched at a high magnification by a tenter (see, for example, Patent Document 1).
If a cellulose ester film is stretched at a high magnification at a high temperature to make it wider and thinner, especially when producing a wide film exceeding 1.6 m, the orientation of the cellulose in each part of the film is likely to be disturbed by the stretching at a high magnification. It was found that the ear-cutting failure occurred when transported at a high speed, and it broke down when severe. In addition, there is a problem in productivity and optical characteristics due to a large variation in each part of the retardation value Ro in the in-plane direction which is important in optical characteristics, and improvement has been demanded.

JP 2010-1383 A

  The present invention has been made in view of the above-mentioned problems and situations, and the solution is to suppress the disturbance of cellulose orientation even when widening is performed by stretching at a high magnification, and there is no ear-cutting failure even at high speed conveyance. An object of the present invention is to provide a stretched cellulose ester film that hardly occurs and has little variation in each part of the in-plane retardation Ro film, and a method for producing the same.

  In order to solve the above problems, the present inventor is a stretched cellulose ester film containing a cellulose ester having a specific acetyl group substitution degree in the process of examining the cause of the above problem, and the width direction of one surface. When a part of the cross-sectional shape is represented by a suspension curve and has a specific film thickness difference in the plane, even if it is widened by stretching at a high magnification, disturbance of cellulose orientation can be suppressed, It has been found that a stretched cellulose ester film can be obtained which is less likely to cause an edge-cutting failure even when transported at a high speed and has a small variation in retardation in the in-plane direction.

  That is, the said subject which concerns on this invention is solved by the following means.

1. A stretched cellulose ester film acetyl group substitution degree containing cellulose ester is in the range of 2.8 to 2.95, part of the cross-sectional shape in one of the width direction of the front surface of the stretched cellulose ester film Is a suspended curve, and the film thickness difference h (maximum film thickness-film end film thickness) is in the range of 1.0 to 4.0 μm.

2. Wherein in the range average of 2.2~3.5nm stretching one central arithmetic average roughness of the front surface of the cellulose ester film (Ra), the end on one front surface of the stretched cellulose ester film The stretched cellulose ester film according to item 1, which is higher in the range of 0.3 to 1.0 nm than the average value of the arithmetic average roughness (Ra) of the part.

Here, when the total width of the stretched cellulose ester film is defined as L, the end portion refers to the end of the film to L × 0.05, and the central portion refers to the total width of the stretched cellulose ester film as L. Sometimes, it means a portion of ± L × 0.1 in the width direction from the center of the film.
3. The stretched cellulose ester film according to item 1 or 2, wherein the stretched cellulose ester film has a width of 2 to 3 m and a maximum film thickness of 30 to 70 μm. .

4). It is a manufacturing method of the stretched cellulose-ester film as described in any one of Claims 1-3, Comprising: Dope which forms this stretched cellulose-ester film is a part of cross-sectional shape in the width direction of the film A surface Is cast on a belt or a drum so as to be represented by a suspension curve, and after peeling, the surface temperature at the end of the A side of the web is 10 to 50 ° C. compared to the surface temperature at the center. A method for producing a stretched cellulose ester film, wherein the stretching treatment is performed while lowering the thickness within a range.
Here, the surface A refers to the surface opposite to the side in contact with the belt surface or drum surface when cast on a belt or drum to form a film dope.

Here, when the total width of the unstretched cellulose ester film is Lo, the end portion refers to the end of the film to Lo × 0.05, and the central portion is the total width of the unstretched cellulose ester film. , A portion of ± Lo × 0.1 in the width direction from the center of the film.
5. In order to adjust the surface temperature of the end portion, at least a pair of end cold air generating portions are provided, and cool air having a temperature lower than the temperature of the central portion is lower than the temperature of the central portion than the end cold air generating portion. The method for producing a stretched cellulose ester film according to item 4, wherein the stretch treatment is performed while spraying the end portion.

  6). Stretching in the width direction of the film at a stretching ratio within the range of 160 to 190 ° C. and a range of 25 to 100% when the stretching process is performed, The manufacturing method of the stretched cellulose-ester film of description.

  According to the present invention, even if the film is stretched at a high magnification to be widened, the disorder of cellulose orientation is suppressed, and even when it is conveyed at high speed, the ear-cutting failure is unlikely to occur, and the in-plane direction retardation value Ro is in each part of the film. A stretched cellulose ester film with little variation and a method for producing the same can be provided.

  The expression mechanism or action mechanism of the effect of the present invention is not clear, but is presumed as follows.

  The conventional stretched cellulose ester film is designed and adjusted to have a uniform film thickness throughout the entire film. However, when the width is particularly 2 m or more, there has been no problem so far when the web is stretched at a high magnification and then conveyed at high speed. The fluttering of the web itself has increased, making it easier for ear-cutting failures to occur and, in severe cases, breaking.

  The center of gravity of the film can be unevenly distributed in the center by increasing the thickness from the end to the center of the film as in the stretched cellulose ester film of the present invention. Even if it is conveyed, it is considered that the fluttering of the web is suppressed and the occurrence of the ear-cutting failure can be suppressed.

  At the same time, by making the center of gravity of the film unevenly distributed in the center, it is possible to suppress disturbance of the cellulose orientation in the width direction during stretching, and the stretched cellulose ester having a small variation in the in-plane retardation value Ro in each part of the film It is believed that a film is obtained.

The schematic diagram which shows the cross-sectional shape of the stretched cellulose-ester film of this invention Schematic side configuration diagram of a production apparatus for producing a stretched cellulose ester film of the present invention Schematic plan view of stretching device (tenter) Schematic diagram of stretched cellulose ester film of the present invention Schematic diagram showing a preferred stretching method for the present invention

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail, but the present invention is not limited thereto.

Stretched cellulose ester film of the present invention is a stretched cellulose ester film acetyl group substitution degree containing cellulose ester is in the range of 2.8 to 2.95, in one front surface of the stretched cellulose ester film A part of the cross-sectional shape in the width direction is represented by a hanging curve, and the film thickness difference h (maximum film thickness-film end film thickness) is in the range of 1.0 to 4.0 μm. Depending on the configuration, even when the film is stretched at a high magnification to be widened, an edge-cutting failure hardly occurs, and a stretched cellulose ester film having little variation in each part of the retardation value Ro in the in-plane direction is obtained.

  This feature is a technical feature common to the inventions according to claims 1 to 6.

The embodiments of the present invention, from the viewpoint of the effect expression of the present invention, the average value of one of the central arithmetic average roughness of the front surface of the stretched cellulose ester film (Ra) is 2.2~3.5nm in the range, when the higher within the 0.3~1.0nm than the average value of the arithmetic mean roughness of the end portion (Ra) on one front surface of the stretched cellulose ester film, which is conveyed at high speed It is preferable for suppressing fluttering of the web and enhancing the effects of the present invention.

  Furthermore, it is a preferable embodiment that 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.

As a method for producing a stretched cellulose ester film for producing the stretched cellulose ester film of the present invention, the dope forming the stretched cellulose ester film is represented by a part of the cross-sectional shape in the width direction of the A surface of the film as a suspension curve. As described above, the web is formed by casting on a belt or a drum, and after peeling, the surface temperature of the end of the A-side of the web is lowered within a range of 10 to 50 ° C. compared to the surface temperature of the center. However, it is possible to control the arithmetic average roughness (Ra) of the central portion and the end portion within a preferable range, and even if the high-speed conveyance is performed after performing high-magnification stretching. It is preferable because flapping of the web is suppressed.
Here, the surface A refers to the surface opposite to the side in contact with the belt surface or drum surface when cast on a belt or drum to form a film dope.

  Further, in order to adjust the surface temperature of the end portion, at least a pair of end cold air generation portions are provided, and the end cold air generation portion has a lower temperature within a range of 10 to 50 ° C. than the temperature of the central portion. It is further preferable as an embodiment to perform a stretching treatment while blowing cold air to the end portion.

  Further, the stretched cellulose ester film can be stretched in the width direction of the film at a stretching ratio in the range of 160 to 190 ° C. and in the range of 25 to 100% when the stretching process is performed. Is a preferable production method for obtaining the above.

  Although a suspension curve is mentioned later, the cross-sectional shape in the width direction of the stretched cellulose ester film of this invention is shown in FIG. 1 as a schematic diagram.

  Each symbol in FIG. 1 represents F: stretched cellulose ester film, A: A surface, B: B surface, Mh: maximum film thickness, Lh: terminal film thickness, and K: suspension curve.

  In the present invention, the cellulose ester film after the stretching treatment is referred to as “stretched cellulose ester film”, and the cellulose ester film before the stretching treatment is referred to as “unstretched cellulose ester film” or “web”.

  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 suspension curve, and has a gentle curve with respect to the film end as shown in FIG. It has a cross section where the film thickness increases toward the center. The “part of the cross-sectional shape in the width direction of the A surface” specifically refers to the cross-sectional shape in the width direction of the surface of the A surface represented by K in FIG.

  Hereinafter, the present invention will be described in detail.

<Description of the suspension curve>
The suspension curve in the present invention refers to a curve that has one vertex and is line-symmetric with respect to the normal line at the vertex.

  The stretched cellulose ester film of the present invention is characterized in that a part of the cross-sectional shape with respect to the width direction of the A plane is represented by an expression representing a suspension curve. As shown in FIG. 1, a part of the cross-sectional shape of the A surface in the width direction is such that the suspension curve is convex upward, so that the film thickness h in the width direction is obtained by reversing the general expression of the suspension curve. Is represented 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 changes in the range of −x / 2 ≦ a ≦ x / 2.

Although a part of the cross-sectional shape with respect to the width direction of the A surface may be represented by the formula (1), in the present invention, the film thickness difference h between the end portion and the central portion of the film (maximum film thickness−film end film) Thickness) is in the range of 1.0 to 4.0 μm (that is, 1.0 × 10 ^{−6 to} 4.0 × 10 ⁻⁶ (m)), and the product width x varies in the range of 2 to 3 m. When a more specific approximate expression is obtained by adding the above conditions, the relational expression of the suspension curve according to the present invention is expressed by Expression (2).

Formula (2) h (m) = − (e ^a + e ^−a ) / b
In the formula, a is in 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 is determined that a part of the cross-sectional shape of the A surface in the width direction is represented by a suspension curve when represented by the above formula (2).

  In order to measure the film thickness in the width direction of the A surface of the stretched cellulose ester film of the present invention, the width direction from the end using, for example, a contact-type film thickness meter (manufactured by Tokyo Seimitsu Co., Ltd .: Micrometer Minicom M). The thickness can be obtained by measuring at intervals of 10 cm. From the obtained film thickness value, a regression equation of film thickness variation with respect to the width direction of the film is obtained, and it can be determined whether it is represented by the expression of the above-mentioned suspension curve.

<Film film forming process>
In the present invention, a dope containing a cellulose ester and other additives is cast on a support (casting process), and then peeled from the support (peeling process), and then the peeled web is stretched. (Stretching process), drying (post-drying process), and winding the film on a roller (winding process), a stretched cellulose ester film is produced.

  Referring to FIG. 2, the cellulose ester film manufacturing apparatus includes a support 1 made of a rotating metal endless belt, and a die 2 that casts a dope that is a raw material solution of the cellulose ester film on the support 1. A peeling roller 3 for peeling the web W formed on the support 1 by the die 2 from the support 1 and a housing for transporting and drying the film F peeled from the support 1 in the width direction. The tenter 4 has a drying device 5 for drying the film F while transporting the film F via a plurality of transport rollers 6, and a winding roller 8 for winding the stretched cellulose ester film F obtained by drying.

  A slit process (ear cutting) is provided between the tenter 4 and the drying device 5 or between the drying device 5 and the winding roller 8 in order to obtain a desired product film width. The slit device is installed at both left and right ends of the film, and the slit device is composed of a disk-shaped rotating upper blade and a roller-shaped rotating lower blade. When the stretched cellulose ester film is transported at a high speed, if the film flutters greatly, the slit cross-sectional quality at the end is inferior in this step, and an ear-cutting failure or a breakage failure is likely to occur.

  Moreover, in FIG. 2, before entering the extending | stretching process by the tenter 4, the heat retention process 4-1 is performed so that the temperature of the unstretched cellulose ester film Fo is not too low, and after the tenter 4 (stretching process), A cooling step 4-2 for gradually cooling the film is provided. Moreover, before the drying process by the drying apparatus 5, the heat retention process 5-1 is performed so that the temperature of the stretched cellulose ester film F does not become too low, and after the drying apparatus 5 (drying process), the film is gradually cooled. A cooling step 5-2 for performing the above is provided.

<Casting process>
In the process of casting the stretched cellulose ester film of the present invention, the filtered dope is fed to a pressure die through a pressure metering gear pump, and the dope is cast from the pressure die onto the metal support at the casting position. Is preferred. In order to make the cross-section (film thickness) of the surface A in the width direction represented by a hanging curve as in the present invention, a pressure die that easily changes the flow rate in the width direction of the casting is preferable. There are coat hanger dies, T dies, etc. as the pressure dies, but all are preferably used. In order to increase the film forming speed, two or more pressure dies are provided on the metal support, and the dope amount is divided. Multiple layers may be used.

  Specifically, the film thickness control represented by the suspension curve is performed so that the dope concentration, the pumped liquid amount, the slit gap of the die base, the extrusion pressure of the die, and the metal support so as to obtain a desired thickness. It is possible to control the speed and the periphery of the die base by increasing the temperature of the edge from the center to provide a difference in viscosity. For simplicity, it is preferable to control the film thickness at the time of casting so that the slit shape of the base part is adjusted and the shape of the web surface approximates to a suspension curve.

<Extension process>
An example of the mechanism of the tenter 4 is shown in FIG. As shown in FIG. 3, the tenter 4 has a large number of clips 11 connected to each other on both the left and right sides of the housing 10, and these clips 11 form a single wheel and run on the rail 12. The unstretched cellulose ester film Fo is gripped and conveyed. Although not shown in the drawings, each clip 11 has a swingable pressing arm, and the both ends in the width direction of the unstretched cellulose ester film Fo on the cradle on both the left and right sides of the tenter 4 It is sandwiched (clipped) between the curved arm tip of the holding arm and the cradle and is transported together while being stretched, and at the same time dried.

  In the tenter 4, the unstretched cellulose ester film Fo is held in the width direction both ends thereof, and the film width holding zone A, the film width direction stretching zone B, and the film width holding zone in the stretched state. The film is successively passed through C, and the film width direction stretching treatment is performed to obtain a stretched cellulose ester film F.

  Here, the film width holding zone A in the tenter 4 is a zone in which the distance between grip clips of the film width (both ends of the base) from the entrance of the tenter 4 to the stretching start point a is constant. The stretching zone B refers to a zone in which the distance between grip clips of the film width (both ends of the base) from the stretching start point a to the stretching end point b of the tenter 4 spreads in the traveling direction (conveying direction). The film width holding zone C in the stretched state is a zone in which the distance between the grip clips of the stretched film width (both ends of the base) from the stretch end point b of the tenter 4 to the grip clip release point c is constant. In the latter half of the film width holding zone C, it is also preferable to provide a relaxation treatment when the transverse stress on the stretched film F is too strong.

  The rail 12 in the tenter 4 is normally a bendable rail. When the rail 12 is bent, the distance between the left and right clips changes, and the width holding zone A, the stretching zone B, and the width holding zone C are configured. can do. The stretching zone B corresponds to the stretching process of the present invention. Note that the combinations of these zones are not limited to those shown in the drawings, and may be combined in any order.

  Moreover, although the illustrated tenter 4 is a clip tenter method, this may be a pin tenter method, and in any case, the tenter method can be dried while maintaining the width of the stretched cellulose ester film F. In order to improve flatness and dimensional stability, it is preferable.

  In order to increase the width of the stretched cellulose ester film of the present invention, it is preferable to stretch the unstretched cellulose ester film Fo in the width direction of the film at a stretch ratio within the range of 25 to 100%. From the viewpoint of avoidance, the draw ratio is more 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 with respect to the width direction of the A surface is represented by a suspension curve. As represented by the suspension curve, a part of the cross-sectional shape with respect to the width direction of the A surface of the unstretched film is cast so as to be represented by the suspension curve.

  In addition, the stretching operation can be performed not only in the width direction (TD direction) of the film but also in the longitudinal direction (MD direction) of the film. A method of stretching in the MD direction using the difference, a method in which both ends of the web are fixed with clips and pins, a distance between the clips and pins is expanded in the advancing direction and stretched in the MD direction, or a MD / TD direction is expanded simultaneously in the MD. / TD The method of extending | stretching to both directions etc. are mentioned.

  The film transport tension in the film forming process such as in the tenter depends on the temperature, but is preferably in the range of 120 to 200 N / m, and more preferably in the range of 140 to 200 N / m. The most preferable range is 140 to 160 N / m.

  The temperature at the time of stretching is within the range of (Tg-30) to (Tg + 100) ° C, more preferably (Tg-20) to (Tg + 80) ° C, where Tg is the glass transition temperature of the stretched cellulose ester film of the present invention. Within the range, more preferably within the range of (Tg-5) to (Tg + 20) ° C. The Tg of the film can be determined by the method described in JIS K7121. The temperature during the specific stretching treatment is preferably in the range of 160 to 190 ° C. It is preferable that the entire tenter 4 is installed in the housing, and hot air is supplied into the housing so as to reach the above temperature from a hot air supply device (not shown) to keep the temperature constant.

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

  FIG. 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, the end is gripped with a clip or the like, and is stretched at a predetermined stretch ratio.

  In the stretched cellulose ester film F of the present invention, the average value of the arithmetic average roughness (Ra) at the end and the average value of the arithmetic average roughness at the central portion are different, and the arithmetic at the central portion of the A surface of the stretched cellulose ester film. The average value of the average roughness (Ra) is within the range of 2.2 to 3.5 nm, and is 0.3 to 1.0 nm than the average value of the arithmetic average roughness (Ra) of the end portion of the film A surface. A height within the range is preferable from the viewpoint of reducing flapping on the roller during high-speed conveyance and further suppressing the ear-cutting failure.

  Here, the term “end” refers to a portion of the stretched cellulose ester film at the end Ho to L × 0.05, where L is the total width of the stretched cellulose ester film. Further, the central portion means a portion of ± L × 0.1 in the width direction from the central portion (L / 2) of the film, where L is the total width of the stretched cellulose ester film, and in FIG. .

  The average value of the arithmetic average roughness (Ra) of the end portion is obtained by selecting 10 points in the longitudinal direction for the end portion (the area H), measuring the arithmetic average roughness (Ra), and obtaining the average value. is there.

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

  The arithmetic average roughness (Ra) is a numerical value defined in JIS B 0601, and examples of the measuring method include a stylus method or an optical method.

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

  FIG. 5 is a schematic view showing a method of stretching treatment preferable for the present invention.

  As a preferable method for producing the stretched cellulose ester film of the present invention, the surface temperature of the A surface end of the unstretched cellulose ester film Fo is 10 to 50 ° C. compared to the surface temperature of the central portion of the unstretched cellulose ester film Fo. It can mention extending | stretching, making it low within the range. However, it is not limited to this method. Here, the A surface of the unstretched cellulose ester film Fo refers to a surface opposite to the belt surface or the side in contact with the drum surface when cast on a belt or drum to form a film dope.

Here, the above-mentioned end portion refers to the end of the film to Lo × 0.05 when the entire width of the unstretched cellulose ester film Fo is Lo, and the central portion refers to the entire width of the unstretched cellulose ester film Fo. Is Lo + 0.1 in the width direction from the center of the film.
The film surface temperature of the edge part and the center part can be measured using a contact-type handy thermometer (ANRITSU DIGITAL THREMOMETER HA-100K). Specifically, 5 points can be measured for each width direction at the point a where the stretching process of the film being transported is started, and the average value can be taken as the film temperature at that site.

  Thus, the arithmetic mean roughness (Ra) can be controlled within the numerical range by changing the temperature during the stretching process between the end and the center. The mechanism has not yet been estimated, but by setting the temperature during the above stretching process to a higher temperature at the center than the end, the cellulose ester resin in the center is softened and the polymer chain of the cellulose ester resin is aligned. Therefore, it is considered that the matting agent is likely to be unevenly distributed in the vicinity of the surface, and the arithmetic average roughness (Ra) varies.

  The method for adjusting the temperature is preferably a method in which cold air is blown locally on the end portion, and at least a pair of end cold air generating portions G1 is provided, and the end cold air generating portion is 10 A method in which stretching is performed while appropriately blowing cold air on the end of the unstretched cellulose ester film Fo so as to be a low temperature within a range of ˜50 ° C. is preferable.

  The end cold air generating part preferably blows cold air, the temperature of which is controlled by a cold air generator (not shown), from the nozzle-like outlet to the entire end of the unstretched cellulose ester film Fo. The distance from the film end to the film end can be appropriately selected, but it is preferable to cover at least the point a before and after the point a at which the unstretched cellulose ester film Fo starts to be stretched. Also, as the area where the cold air is blown, when the entire width of the unstretched cellulose ester film Fo is Lo, covering the part from the end of the film to Lo × 0.2 efficiently adjusts the temperature at the end and the center. It can be carried out in a preferable manner.

  In the stretching step, it is preferable that the temperature distribution in the width direction of the atmosphere is small from the viewpoint of improving the uniformity of the film, and the temperature distribution in the width direction at the edge and the center is preferably within ± 5 ° C. Within ± 2 ° C is more preferred, and within ± 1 ° C is most preferred.

  In FIG. 5, a pair of end cold air generating portions G1 are provided in the vicinity of the stretching start point a so as to cover both ends of the unstretched cellulose ester film Fo. The position of the end cold air generating part G1 in FIG. 5 indicates a preferable position, and is not limited to this.

  Further, it is also preferable to provide an end cold air generating part G2 after the stretching end point b, and by setting the cold air temperature between the center temperature and the end temperature of the stretched cellulose ester film, the high-speed conveyance suitability is further improved. Can do.

  Hereinafter, the material used for this invention is demonstrated.

<Cellulose ester>
As for the cellulose ester used for the stretched cellulose ester film of this invention, the average acetyl group substitution degree of the whole cellulose ester exists in the range of 2.8-2.95. The average degree of acetyl group substitution is more preferably in the range of 2.85 to 2.95. The measuring method of the acetyl group substitution degree of a cellulose ester can be measured according to ASTM-D817-96.

  The cellulose ester used in the present invention is not particularly limited as long as the above acetyl group substitution degree is satisfied, but the cellulose ester is a carboxylic acid ester having about 2 to 22 carbon atoms, and may be an ester of an aromatic carboxylic acid, In particular, a lower fatty acid ester of cellulose is preferable. The lower fatty acid in the lower fatty acid ester of cellulose means a fatty acid having 6 or less carbon atoms. The acyl group bonded to the hydroxy group may be linear or branched, and may form a ring. Furthermore, another substituent may be substituted. When the degree of substitution is the same, birefringence decreases when the number of carbon atoms is large, and therefore, the number of carbon atoms is preferably selected from acyl groups having 2 to 6 carbon atoms. The cellulose ester preferably has 2 to 4 carbon atoms, more preferably 2 to 3 carbon atoms.

  The cellulose ester may be an acyl group derived from a mixed acid, and particularly preferably an acyl group having 2 and 3 carbon atoms or 2 and 4 carbon atoms. In the present invention, as the cellulose ester, a mixed fatty acid ester of cellulose to which a propionate group or a butyrate group is bonded in addition to an acetyl group such as cellulose acetate propionate, cellulose acetate butyrate, or cellulose acetate propionate butyrate is used. Can do. The butyryl group that forms butyrate may be linear or branched.

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

  When the degree of substitution of the acetyl group is within the above range, there are few unreacted parts with respect to the hydroxy group of the pyranose ring constituting the skeleton of the cellulose resin, and the remaining hydroxy group is reduced, resulting in dimensional change and warping. In addition, no slit defects during high-speed conveyance are observed, and the physical properties as a binder are high.

  In addition, when the average degree of acetyl group substitution is within the above range, the disorder of the orientation of cellulose when stretched at a high magnification becomes small, and the effect of suppressing variation in retardation is high.

  The weight average molecular weight (Mw) of the cellulose ester according to the present invention is preferably 75000 or more, and 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, it is excellent in heat resistance and brittleness, and since the viscosity range is appropriate, film formation is facilitated.

  The weight average molecular weight (Mw) of a cellulose ester can be measured as follows.

  Measured by high performance liquid chromatography under the following conditions.

Solvent: Methylene chloride Column: Shodex K806, K805, K803G (Used by connecting three Showa Denko Co., Ltd.)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (GL Science Co., Ltd.)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0 ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corp.) Mw = 100000 to 500 samples were used. The 13 samples are preferably used at approximately equal intervals.

  Although there is no limitation in particular as a cellulose of the raw material of the cellulose ester used for this invention, Wood pulp (a softwood pulp, a hardwood pulp), a cotton linter, etc. can be used. The Mw of the cellulose ester can be controlled by the type of cellulose and the use of a plurality of raw material celluloses. For example, when esterification is performed using hardwood hydrolyzed kraft pulp, Mw of cellulose ester increases, and when softwood sulfite pulp is used, Mw tends to decrease. Therefore, cellulose may be used singly or in combination of two or more. For example, softwood pulp and cotton linter or hardwood pulp may be used in combination. As cellulose, usually pulp (particularly softwood pulp) is often used. In addition, the α-cellulose content (% by mass) of cellulose is usually from 94 to 99 (for example, 95 to 99), preferably from about 96 to 98.5 (for example, 97.3 to 98). .

In the cellulose ester according to the present invention, when the acylating 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 methylene chloride is used. The reaction is carried out using a protic catalyst such as sulfuric acid. When the acylating agent is acid chloride (CH ₃ COCl, C ₂ H ₅ COCl, C ₃ H ₇ COCl), the reaction is carried out using a basic compound such as an amine as a catalyst. Specifically, it can be synthesized with reference to the method described in JP-A-10-45804.

  Cellulose esters are also affected by trace metal components in cellulose esters. These are considered to be related to water used in the production process, but it is preferable that there are few components that can become insoluble nuclei, and metal ions such as iron, calcium, and magnesium contain organic acidic groups. Insoluble matter may be formed by salt formation with a polymer degradation product or the like that may be present, and it is preferable that the amount is small. The iron (Fe) component is preferably 1 ppm or less. As for the calcium (Ca) component, it is easy to form a coordination compound, that is, a complex with an acidic component such as carboxylic acid or sulfonic acid, and many ligands. Starch, turbidity).

  The calcium (Ca) component is 60 ppm or less, preferably in the range of 0 to 30 ppm. The magnesium (Mg) component is preferably in the range of 0 to 70 ppm, and more preferably in the range of 0 to 20 ppm, since too much will cause insoluble matter. Metal components such as iron (Fe) content, calcium (Ca) content, magnesium (Mg) content, etc. are pre-processed by completely digesting cellulose ester with micro digest wet cracking equipment (sulfuric acid decomposition) and alkali melting. After being performed, it can be analyzed using ICP-AES (Inductively Coupled Plasma Atomic Emission Spectrometer).

(Plasticizer)
The stretched cellulose ester film of the present invention does not break during stretching, and preferably contains an appropriate amount of a plasticizer as necessary to obtain the effects of the present invention. The plasticizer is not particularly limited, but is preferably a polyhydric alcohol ester plasticizer, a polycarboxylic acid ester plasticizer, a glycolate plasticizer, a phthalate ester plasticizer, a fatty acid ester plasticizer, and a polyester type. It is selected from plasticizers and acrylic plasticizers.

  The polyhydric alcohol ester is composed of an ester of a dihydric or higher aliphatic polyhydric alcohol and a monocarboxylic acid, and preferably has an aromatic ring or a cycloalkyl ring in the molecule.

  The polyhydric alcohol used is represented by the following general formula (1).

General formula (1) R1- (OH) _n
(In the formula, R1 represents an n-valent organic group, and n represents a positive integer of 2 or more.)
Examples of preferred polyhydric alcohols include the following, but the present invention is not limited to these. Adonitol, arabitol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3- Butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol, 1,6-hexanediol, hexanetriol, galactitol, mannitol, 3-methylpentane- Examples thereof include 1,3,5-triol, pinacol, sorbitol, trimethylolpropane, trimethylolethane, xylitol, pentaerythritol, dipentaerythritol and the like. Of these, trimethylolpropane and pentaerythritol are preferable.

  There is no restriction | limiting in particular as monocarboxylic acid used for polyhydric alcohol ester, Well-known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylic acid, etc. can be used. Use of an alicyclic monocarboxylic acid or aromatic monocarboxylic acid is preferable in terms of improving moisture permeability and retention. Examples of preferred monocarboxylic acids include the following, but are not limited thereto.

  As the aliphatic monocarboxylic acid, a fatty acid having a straight chain or a side chain having 1 to 32 carbon atoms can be preferably used. It is more preferable that it is C1-C20, and it is especially preferable that it is C1-C10. The use of acetic acid is preferred because the compatibility with the cellulose ester is increased, and it is also preferred to use a mixture of acetic acid and another monocarboxylic acid.

  Preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, lauric acid, tridecylic acid , Saturated fatty acids such as myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, laccelic acid, undecylenic acid, Examples thereof include unsaturated fatty acids such as oleic acid, sorbic acid, linoleic acid, linolenic acid and arachidonic acid. Examples of preferred alicyclic monocarboxylic acids include cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, or derivatives thereof. Examples of preferred aromatic monocarboxylic acids include those in which an alkyl group is introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, and two or more benzene rings such as biphenyl carboxylic acid, naphthalene carboxylic acid, and tetralin carboxylic acid. The aromatic monocarboxylic acid which has, or derivatives thereof can be mentioned. In particular, benzoic acid is preferred.

  The molecular weight of the polyhydric alcohol ester is preferably in the range of 300 to 1500, more preferably in the range of 350 to 750. A higher molecular weight is preferred because it is less likely to volatilize, and a smaller one is preferred in terms of moisture permeability and compatibility with cellulose ester. The carboxylic acid used for the polyhydric alcohol ester may be one kind or a mixture of two or more kinds. Moreover, all the OH groups in the polyhydric alcohol may be esterified, or a part of the OH groups may be left as they are. The specific compound of a polyhydric alcohol ester is shown below.

  In addition, trimethylolpropane triacetate, pentaerythritol tetraacetate and the like are also preferably used.

  The glycolate plasticizer is not particularly limited, but alkylphthalylalkyl glycolates can be preferably used. Examples of alkyl phthalyl alkyl glycolates include methyl phthalyl methyl glycolate, ethyl phthalyl ethyl glycolate, propyl phthalyl propyl glycolate, butyl phthalyl butyl glycolate, octyl phthalyl octyl glycolate, methyl phthalyl ethyl Glycolate, ethyl phthalyl methyl glycolate, ethyl phthalyl propyl glycolate, methyl phthalyl butyl glycolate, ethyl phthalyl butyl glycolate, butyl phthalyl methyl glycolate, butyl phthalyl ethyl glycolate, propyl phthalyl butyl glycol Butyl phthalyl propyl glycolate, methyl phthalyl octyl glycolate, ethyl phthalyl octyl glycolate, octyl phthalyl methyl glycolate, octyl phthalate Ethyl glycolate, and the like.

  Examples of the phthalate ester plasticizer include diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, dioctyl phthalate, dicyclohexyl phthalate, and dicyclohexyl terephthalate.

  Examples of the citrate plasticizer include acetyl trimethyl citrate, acetyl triethyl citrate, and acetyl tributyl citrate.

  Examples of fatty acid ester plasticizers include butyl oleate, methylacetyl ricinoleate, and dibutyl sebacate.

  Examples of the phosphate ester plasticizer include triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate and the like.

  The polyvalent carboxylic acid ester compound is composed of an ester of a divalent or higher, preferably 2 to 20 valent polyvalent carboxylic acid and an alcohol. The aliphatic polyvalent carboxylic acid is preferably 2 to 20 valent, and in the case of an aromatic polyvalent carboxylic acid or an alicyclic polyvalent carboxylic acid, it is preferably 3 to 20 valent.

  The polyvalent carboxylic acid is represented by the following general formula (2).

General formula (2) R2 (COOH) _m (OH) _n
(Where R2 is an (m + n) -valent organic group, m is a positive integer of 2 or more, n is an integer of 0 or more, a COOH group is a carboxy group, and an OH group is an alcoholic or phenolic hydroxy group)
Examples of preferred polyvalent carboxylic acids include the following, but the present invention is not limited to these. Trivalent or higher polyvalent aromatic polycarboxylic acids such as trimellitic acid, trimesic acid, pyromellitic acid or derivatives thereof, succinic acid, adipic acid, azelaic acid, sebacic acid, oxalic acid, fumaric acid, maleic acid, tetrahydrophthal An aliphatic polyvalent carboxylic acid such as an acid, an oxypolyvalent carboxylic acid such as tartaric acid, tartronic acid, malic acid and citric acid can be preferably used. In particular, it is preferable to use an oxypolycarboxylic acid from the viewpoint of improving retention.

  There is no restriction | limiting in particular as alcohol used for the polyhydric carboxylic acid ester compound which can be used for this invention, Well-known alcohol and phenols can be used. For example, an aliphatic saturated alcohol or aliphatic unsaturated alcohol having a straight chain or side chain having 1 to 32 carbon atoms can be preferably used. It is more preferable that it is C1-C20, and it is especially preferable that it is C1-C10. In addition, alicyclic alcohols such as cyclopentanol and cyclohexanol or derivatives thereof, aromatic alcohols such as benzyl alcohol and cinnamyl alcohol, or derivatives thereof can also be preferably used.

  When an oxypolycarboxylic acid is used as the polycarboxylic acid, the alcoholic or phenolic hydroxy group of the oxypolycarboxylic acid may be esterified with a monocarboxylic acid. Examples of preferred monocarboxylic acids include the following, but the present invention is not limited thereto.

  As the aliphatic monocarboxylic acid, a fatty acid having a straight chain or a side chain having 1 to 32 carbon atoms can be preferably used. It is more preferable that it is C1-C20, and it is especially preferable that it is C1-C10.

  Preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, lauric acid, tridecylic acid, Saturated fatty acids such as myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, and laccelic acid, undecylenic acid, olein Examples thereof include unsaturated fatty acids such as acid, sorbic acid, linoleic acid, linolenic acid, and arachidonic acid.

  Examples of preferred alicyclic monocarboxylic acids include cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, or derivatives thereof.

  Examples of preferred aromatic monocarboxylic acids include those in which an alkyl group is introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, and two or more benzene rings such as biphenyl carboxylic acid, naphthalene carboxylic acid, and tetralin carboxylic acid. Aromatic monocarboxylic acids possessed by them, or derivatives thereof. Particularly preferred are acetic acid, propionic acid, and benzoic acid.

  The molecular weight of the polyvalent carboxylic acid ester compound is not particularly limited, but is preferably in the range of 300 to 1000, and more preferably in the range of 350 to 750. The larger one is preferable in terms of improvement in retention, and the smaller one is preferable in terms of moisture permeability and compatibility with cellulose ester.

  The alcohol used for the polyvalent carboxylic acid ester may be one kind or a mixture of two or more kinds.

  The acid value of the polyvalent carboxylic acid ester compound is preferably 1 mgKOH / g or less, and more preferably 0.2 mgKOH / g or less. Setting the acid value in the above range is preferable because the environmental fluctuation of the retardation is also suppressed.

(Acid value)
The acid value refers to the number of milligrams of potassium hydroxide necessary for neutralizing the acid (carboxy group present in the sample) contained in 1 g of the sample. The acid value is measured according to JIS K0070.

  Examples of particularly preferred polyvalent carboxylic acid ester compounds are shown below, but the present invention is not limited thereto. For example, triethyl citrate, tributyl citrate, acetyl triethyl citrate (ATEC), acetyl tributyl citrate (ATBC), benzoyl tributyl citrate, acetyl triphenyl citrate, acetyl tribenzyl citrate, dibutyl tartrate, diacetyl dibutyl tartrate, Examples include tributyl trimellitic acid and tetrabutyl pyromellitic acid.

(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 the cellulose ester is referred to as a sugar ester compound). It is preferable for preventing haze caused by stretching and promoting uniform retardation.

（式中、Ｒ_１〜Ｒ_８は、水素原子、置換若しくは無置換の炭素数２〜２２のアルキルカルボニル基、あるいは、置換又は無置換の炭素数２〜２２のアリールカルボニル基を表し、Ｒ_１〜Ｒ_８は、同じであっても、異なっていてもよい。）
本発明に用いられる一般式（３）で表される化合物の平均置換度は３．０〜６．５であることが、延伸処理においてヘイズ上昇を抑制し、均一な位相差を発現する上でも有効である。平均置換度はより好ましくは４．５〜６．５の範囲である。

(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; R ₁ to R ₈ may be the same or different.)
The average degree of substitution of the compound represented by the general formula (3) used in the present invention is 3.0 to 6.5 in order to suppress an increase in haze and develop a uniform retardation in the stretching treatment. It is valid. The average degree of substitution is more 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) represents the number of substituents other than hydrogen among the eight hydroxy groups included in the general formula (3). In addition, among R _{1 to} R _{8 in} the general formula (3), a number including a group other than hydrogen is represented. Therefore, when all of R _{1 to} R ₈ are substituted with a substituent other than hydrogen, the degree of substitution is 8.0, which is the maximum value, and when R _{1 to} R ₈ are all hydrogen atoms, 0.0 It becomes.

  In the compound represented by the general formula (3), it is difficult to synthesize a single kind of compound in which the number of hydroxy groups and the number of OR groups are fixed, and the number of hydroxy groups and the OR groups in the formula are different. Since it is known that it becomes a compound in which several components are mixed, it is appropriate to use the average substitution degree as the substitution degree of the general formula (3) in the present invention. The average substitution degree can be measured from the area ratio of the chart showing the substitution degree distribution.

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

  Glucose, galactose, mannose, fructose, xylose or arabinose, lactose, sucrose, nystose, 1F-fructosyl nystose, stachyose, maltitol, lactitol, lactulose, cellobiose, maltose, cellotriose, maltotriose, raffinose or kestose .

  In addition, gentiobiose, gentiotriose, gentiotetraose, xylotriose, galactosyl sucrose, and the like are also included.

  The monocarboxylic acid used in the synthesis of the sugar ester compound used in the present invention is not particularly limited, and known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylic acid and the like can be used. . The carboxylic acid 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, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, Saturated lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, mellicic acid, and laxaric acid Examples thereof include unsaturated fatty acids such as fatty acids, undecylenic acid, oleic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid and octenoic acid.

  Examples of preferred alicyclic monocarboxylic acids include cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, or derivatives thereof.

  Examples of preferable aromatic monocarboxylic acids include aromatic monocarboxylic acids having 1 to 5 alkyl groups or alkoxy groups introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, cinnamic acid, benzylic acid, An aromatic monocarboxylic acid having two or more benzene rings such as biphenyl carboxylic acid, naphthalene carboxylic acid and tetralin carboxylic acid, or a derivative thereof can be mentioned, and benzoic acid is particularly preferable.

Some specific examples of the sugar ester compound represented by the general formula (3) are shown below, and these are cases where R _{1 to} R ₈ are all the same substituent R, and the present invention includes them. It is not limited. In the following table, when the average degree of substitution is less than 8.0, any one of R _{1 to} R ₈ represents a hydrogen atom.

  The sugar ester compound used in the present invention can be produced by reacting a sugar with an acylating agent (also referred to as an esterifying agent, for example, an acid halide of acetyl chloride, an anhydride such as acetic anhydride). The distribution of the degree of substitution is made by adjusting the amount of acylating agent, the timing of addition, and the esterification reaction time, but it is possible to mix sugar ester compounds with different degrees of substitution or compounds with different degrees of substitution purely isolated. By mixing, components having a target average substitution degree and a substitution degree of 4 or less can be adjusted.

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

  Four-headed Kolben equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen gas inlet tube were charged with 34.2 g (0.1 mol) of sucrose, 135.6 g (0.6 mol) of benzoic anhydride, 284. 8 g (3.6 mol) was charged, the temperature was raised while bubbling nitrogen gas through a nitrogen gas introduction tube with stirring, and an esterification reaction was carried out at 70 ° C. for 5 hours.

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

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

  Similarly, 158.2 g (0.7 mol) of benzoic anhydride, 146.9 g (0.65 mol), 135.6 g (0.6 mol), 124.3 g (0.55 mol) and equimolar pyridine. To obtain sugar esters of components as shown in Table 1.

  Next, by purifying a part of the obtained mixture by column chromatography using silica gel, each of A-1, A-2, A-3, A-4, A-5 and the like having a purity of 100% is obtained. Obtained.

  A-5 or the like means a mixture of all components having a substitution degree of 4 or less, that is, compounds having a substitution degree of 4, 3, 2, 1. The average substitution degree was calculated with A-5 and the like being the substitution degree 4.

  In the present invention, the average degree of substitution was adjusted by adding in combination the sugar ester close to the desired degree of average substitution, isolated A-1 to A-5, and the like by the method prepared here.

<Measurement conditions for HPLC-MS>
1) LC section Device: JASCO CO., LTD. Column oven (JASCO CO-965), detector (JASCO UV-970-240 nm), pump (JASCO PU-980), degasser (JASCO DG-980-50)
Column: Inertsil ODS-3 Particle size 5 μm 4.6 × 250 mm (manufactured by GL Sciences Inc.)
Column temperature: 40 ° C
Flow rate: 1 ml / min
Mobile phase: THF (1% acetic acid): H ₂ O (50:50)
Injection volume: 3 μl
2) MS unit Device: LCQ DECA (manufactured by Thermo Quest Co., Ltd.)
Ionization method: Electrospray ionization (ESI) method Spray Voltage: 5 kV
Capillary temperature: 180 ° C
Vaporizer temperature: 450 ° C
The stretched cellulose ester film of the present invention preferably contains the sugar ester compound in a range of 1 to 20% by mass, particularly in a range of 3 to 15% by mass. Within this range, the excellent effect of the present invention of stabilizing the retardation is exhibited, and there is no bleed out during storage of the original fabric, which is preferable.

(Polyester compound)
The stretched cellulose ester film of the present invention preferably contains a polyester compound represented by the following general formula (4) from the viewpoint of preventing haze due to stretching and suppressing breakage and the like.

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

Formula (4) B- (GA) _n -GB
(In the formula, B is a benzene monocarboxylic acid residue, G is an alkylene glycol residue having 2 to 12 carbon atoms, an aryl glycol residue having 6 to 12 carbon atoms, or an oxyalkylene glycol residue having 4 to 12 carbon atoms, A represents an alkylene dicarboxylic acid residue having 4 to 12 carbon atoms or an aryl dicarboxylic acid residue having 6 to 12 carbon atoms, and n represents an integer of 1 or more.)
In the general formula (4), a benzene monocarboxylic acid residue represented by B and an alkylene glycol residue, oxyalkylene glycol residue or aryl glycol residue represented by G, an alkylene dicarboxylic acid residue or aryl dicarboxylic group represented by A It is composed of an acid residue and can be obtained by a reaction similar to that of a normal polyester plasticizer.

  Examples of the benzene monocarboxylic acid component of the polyester plasticizer include benzoic acid, para-tert-butylbenzoic acid, orthotoluic acid, metatoluic acid, p-toluic acid, dimethylbenzoic acid, ethylbenzoic acid, normal propylbenzoic acid, and aminobenzoic acid. And acetoxybenzoic acid and the like, and these can be used as one kind or a mixture of two or more kinds, respectively.

  Examples of the alkylene glycol component having 2 to 12 carbon atoms of the polyester plasticizer include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1, 2-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 2, 2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3-propanediol (3,3-dimethylolheptane), 3-methyl-1 , 5-pentanediol 1,6-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl There are 1,3-hexanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-octadecanediol, and the like. Used as a mixture of two or more. In particular, an alkylene glycol having 2 to 12 carbon atoms is particularly preferable because of excellent compatibility with a cellulose ester.

  In addition, examples of the oxyalkylene glycol component having 4 to 12 carbon atoms of the aromatic terminal ester include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tripropylene glycol. It can be used as a seed or a mixture of two or more.

  Examples of the alkylene dicarboxylic acid component having 4 to 12 carbon atoms of the aromatic terminal ester include succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, and dodecanedicarboxylic acid. These are used as one kind or a mixture of two or more kinds. Examples of the arylene dicarboxylic acid component having 6 to 12 carbon atoms include phthalic acid, terephthalic acid, isophthalic acid, 1,5-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, and the like.

  The number average molecular weight of the polyester plasticizer is preferably in the range of 300 to 1500, and more preferably in the range of 400 to 1000. The acid value is 0.5 mgKOH / g or less, 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.

  Hereinafter, synthesis examples of the aromatic terminal ester plasticizer will be shown.

<Sample No. 1 (Aromatic terminal ester sample)>
A reaction vessel was charged with 410 parts of phthalic acid, 610 parts of benzoic acid, 737 parts of dipropylene glycol, and 0.40 part of tetraisopropyl titanate as a catalyst. While the monohydric alcohol was refluxed, heating was continued within the range of 130 to 250 ° C. until the acid value became 2 or less, and water produced was continuously removed. Next, the distillate is removed under a reduced pressure of 1.33 × 10 ⁴ Pa to 4 × 10 ² Pa or less within a range of 200 to 230 ° C., and then filtered to obtain an aromatic terminal having the following properties: An ester plasticizer was obtained.

Viscosity (25 ° C., mPa · s); 43400
Acid value: 0.2
<Sample No. 2 (Aromatic terminal ester sample)>
Sample No. 1 was used except that 410 parts of phthalic acid, 610 parts of benzoic acid, 341 parts of ethylene glycol, and 0.35 part of tetraisopropyl titanate as a catalyst were used in the reaction vessel. In the same manner as in No. 1, an aromatic terminal ester having the following properties was obtained.

Viscosity (25 ° C., mPa · s); 31000
Acid value: 0.1
<Sample No. 3 (Aromatic terminal ester sample)>
Sample No. 1 was used except that 410 parts of phthalic acid, 610 parts of benzoic acid, 418 parts of 1,2-propanediol, and 0.35 part of tetraisopropyl titanate as the catalyst were used in the reaction vessel. In the same manner as in No. 1, 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)>
Sample No. 4 was used except that 410 parts of phthalic acid, 610 parts of benzoic acid, 418 parts of 1,3-propanediol, and 0.35 part of tetraisopropyl titanate as a catalyst were used in the reaction vessel. In the same manner as in No. 1, an aromatic terminal ester having the following properties was obtained.

Viscosity (25 ° C., mPa · s); 37000
Acid value: 0.05
Although the specific compound of an aromatic terminal ester plasticizer is shown below, this invention is not limited to this.

  The stretched cellulose ester film of the present invention preferably contains the polyester-based compound in the stretched cellulose ester film within a range of 1 to 20% by mass, particularly within a range of 3 to 11% by mass. If it is in this range, while exhibiting the outstanding effect of this invention, failures, such as a fracture | rupture, can be suppressed.

(UV absorber)
The stretched cellulose ester film of the present invention can also contain an ultraviolet absorber. The ultraviolet absorber is intended to improve durability by absorbing ultraviolet rays of 400 nm or less, and in particular, the transmittance at a wavelength of 370 nm is preferably 10% or less, more preferably 5% or less, and further Preferably it is 2% or less.

  Although the ultraviolet absorber used in the present invention is not particularly limited, for example, oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, triazine compounds, nickel complex compounds, inorganic powders Examples include the body.

  For example, 5-chloro-2- (3,5-di-sec-butyl-2-hydroxylphenyl) -2H-benzotriazole, (2-2H-benzotriazol-2-yl) -6- (linear and side Chain dodecyl) -4-methylphenol, 2-hydroxy-4-benzyloxybenzophenone, 2,4-benzyloxybenzophenone, etc., and tinuvin 109, tinuvin 171, tinuvin 234, tinuvin 326, tinuvin 327, tinuvin 328, etc. These are commercially available products made by BASF Japan and can be preferably used.

  The UV absorbers preferably used in the present invention are benzotriazole UV absorbers, benzophenone UV absorbers, and triazine UV absorbers, particularly preferably benzotriazole UV absorbers and benzophenone UV absorbers. .

  Although the specific example of the benzotriazole type ultraviolet absorber used for this invention below is given, this invention is not limited to these.

UV-1: 2- (2'-hydroxy-5'-methylphenyl) benzotriazole UV-2: 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl) benzotriazole UV-3 : 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) benzotriazole UV-4: 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl)- 5-Chlorobenzotriazole UV-5: 2- (2'-hydroxy-3 '-(3 ", 4", 5 ", 6" -tetrahydrophthalimidomethyl) -5'-methylphenyl) benzotriazole UV-6: 2,2-methylenebis (4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol)
UV-7: 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole UV-8: 2- (2H-benzotriazol-2-yl) -6 (Linear and side chain dodecyl) -4-methylphenol (TINUVIN171)
UV-9: Octyl-3- [3-tert-butyl-4-hydroxy-5- (chloro-2H-benzotriazol-2-yl) phenyl] propionate and 2-ethylhexyl-3- [3-tert-butyl- 4-Hydroxy-5- (5-chloro-2H-benzotriazol-2-yl) phenyl] propionate mixture (TINUVIN 109)
Specific examples of the benzophenone-based ultraviolet absorber are shown below, but the present invention is not limited thereto.

UV-10: 2,4-dihydroxybenzophenone UV-11: 2,2'-dihydroxy-4-methoxybenzophenone UV-12: 2-hydroxy-4-methoxy-5-sulfobenzophenone UV-13: Bis (2-methoxy -4-hydroxy-5-benzoylphenylmethane)
In addition, a discotic compound such as a compound having a 1,3,5-triazine ring is also preferably used as the ultraviolet absorber.

  The stretched cellulose ester film of the present invention preferably contains two or more ultraviolet absorbers.

  As the UV absorber, a polymer UV absorber can also be preferably used, and in particular, a polymer type UV absorber described in JP-A-6-148430 is preferably used.

  The method of adding the UV absorber can be added to the dope after dissolving the UV absorber in an alcohol such as methanol, ethanol or butanol, an organic solvent such as methylene chloride, methyl acetate, acetone or dioxolane or a mixed solvent thereof. Or you may add directly in dope composition. For an inorganic powder that does not dissolve in an organic solvent, a dissolver or a sand mill is used in the organic solvent and cellulose ester to disperse and then added to the dope.

  The amount of UV absorber used is not uniform depending on the type of UV absorber, usage conditions, etc., but when the dry film thickness of the stretched cellulose ester film is within the range of 30 to 200 μm, the stretched cellulose ester film is used. The range of 0.5 to 10% by mass is preferable, and the range of 0.6 to 4% by mass is more preferable.

(Fine particles)
The stretched cellulose ester film of the present invention preferably contains fine particles from the viewpoint of adjusting the arithmetic average roughness (Ra) to improve the slipperiness and eliminating poor conveyance such as slipping.

  As fine particles, examples of inorganic compounds include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, Examples thereof include magnesium silicate and calcium phosphate. Fine particles containing silicon are preferable in terms of low turbidity, and silicon dioxide is particularly preferable.

  The average primary particle size 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 may be mainly contained as secondary aggregates having a particle size in the range of 0.05 to 0.3 μm, and if the particles have an average particle size in the range of 100 to 400 nm, the primary particles are not aggregated. It is also preferable that it is contained. The content of these 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 having a multilayer structure by the co-casting method, it is preferable to contain fine particles of this addition amount on the surface.

  Silicon dioxide fine particles are commercially available, for example, under the trade names Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (above Nippon Aerosil Co., Ltd.). it can.

  Zirconium oxide fine particles are commercially available, for example, under the trade names Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.) and can be used.

  Examples of the polymer include silicone resin, fluororesin, and acrylic resin. Silicone resins are preferable, and those having a three-dimensional network structure are particularly preferable. For example, Tospearl 103, 105, 108, 120, 145, 3120, and 240 (manufactured by Toshiba Silicone Co., Ltd.) It is marketed by name and can be used.

  Among these, Aerosil 200V and Aerosil R972V are particularly preferably used because they have a large effect of reducing the friction coefficient while keeping the haze of the stretched cellulose ester film low. In the stretched cellulose ester film of the present invention, the dynamic friction coefficient of at least one surface is preferably in the range of 0.2 to 1.0.

(dye)
A dye can also be added to the stretched cellulose ester film of the present invention for color adjustment. For example, a blue dye may be added to suppress the yellowness of the film. Preferred examples of the dye include anthraquinone dyes.

  The anthraquinone dye may have an arbitrary substituent at an arbitrary position from the 1st position to the 8th position of the anthraquinone. Preferred substituents include an anilino group, a hydroxy group, an amino group, a nitro group, or a hydrogen atom. In particular, it is preferable to contain a blue dye described in JP-A-2001-154017, particularly an anthraquinone dye.

  Various additives may be batch-added to a dope that is a cellulose ester-containing solution before film formation, or an additive solution may be separately prepared and added in-line. In particular, it is preferable to add a part or all of the fine particles in-line in order to reduce the load on the filter medium.

  When the additive solution is added in-line, it is preferably dissolved in a small amount of cellulose ester in order to improve mixing with the dope. The amount of the cellulose ester is preferably in the range of 1 to 10 parts by mass, more preferably in the range of 3 to 5 parts by mass with respect to 100 parts by mass of the solvent.

  In order to perform in-line addition and mixing in the present invention, for example, an in-line mixer such as a static mixer (manufactured by Toray Engineering), SWJ (Toray static type in-tube mixer Hi-Mixer) or the like is preferably used.

<Method for producing stretched cellulose ester film>
Next, about the manufacturing method of the stretched cellulose-ester film of this invention, it demonstrates except the casting process which performs flow control by the said die | dye, and a extending | stretching process process.

  The stretched cellulose ester film of the present invention can be preferably used, whether it is a film produced by a solution casting method or a film produced by a melt casting method.

  In the production of the stretched cellulose ester film of the present invention by the solution casting method, the cellulose ester and the additive are dissolved in a solvent to prepare a dope, and the dope is cast on an endless metal support that moves indefinitely. It is performed by a step, a step of drying the cast dope as a web, a step of peeling from the metal support, a step of stretching or maintaining the width, a step of further drying, and a step of winding up the finished film.

  The process for preparing the dope will be described. The concentration of cellulose ester in the dope is preferably higher because the drying load after casting on the metal support can be reduced. However, if the concentration of cellulose ester is too high, the load during filtration increases and the filtration accuracy is poor. Become. The concentration for achieving both of these is preferably in the range of 10 to 35% by mass, more preferably in the range of 15 to 25% by mass.

  The solvent used in the dope may be used alone or in combination of two or more, but it is preferable to use a mixture of a good solvent and a poor solvent of cellulose ester in terms of production efficiency, and there are many good solvents. This is preferable from the viewpoint of the solubility of the cellulose ester. The preferable range of the mixing ratio of the good solvent and the poor solvent is that the good solvent is in the range of 70 to 98% by mass, and the poor solvent is in the range of 2 to 30% by mass. With a good solvent and a poor solvent, what dissolve | melts the cellulose ester to be used independently is defined as a good solvent, and what poorly swells or does not melt | dissolve is defined as a poor solvent. Therefore, depending on the average acetylation degree (acetyl group substitution degree) of the cellulose ester, the good solvent and the poor solvent change. For example, when acetone is used as the solvent, the cellulose ester acetate ester (acetyl group substitution degree 2.4), cellulose Acetate propionate is a good solvent, and cellulose acetate (acetyl group substitution degree 2.8) is a poor solvent.

  The good solvent is not particularly limited, and examples thereof include organic halogen compounds such as methylene chloride, dioxolanes, acetone, methyl acetate, and methyl acetoacetate. Particularly preferred is methylene chloride or methyl acetate.

  Moreover, although a poor solvent is not specifically limited, For example, methanol, ethanol, n-butanol, cyclohexane, cyclohexanone etc. are used preferably. Moreover, it is preferable to contain in the dope in the range of 0.01-2 mass% in dope. Moreover, the solvent used for melt | dissolution of a cellulose ester collect | recovers the solvent removed from the film by drying at the film-forming process, and uses this again. The recovery solvent may contain trace amounts of additives added to the cellulose ester, such as plasticizers, UV absorbers, polymers, monomer components, etc., but even if these are included, they are preferably reused. Can be purified and reused if necessary.

  As a method for dissolving the cellulose ester when preparing the dope, a general method can be used. When heating and pressurization are combined, it is possible to heat above the boiling point at normal pressure. It is preferable to stir and dissolve while heating at a temperature that is equal to or higher than the boiling point of the solvent at normal pressure and that the solvent does not boil under pressure, in order to prevent the generation of massive undissolved materials called gels and mamacos. A method in which a cellulose ester is mixed with a poor solvent and wetted or swollen, and then a good solvent is added and dissolved is also preferably used.

  The pressurization may be performed by a method of injecting an inert gas such as nitrogen gas or a method of increasing the vapor pressure of the solvent by heating. Heating is preferably performed from the outside. For example, a jacket type is preferable because temperature control is easy.

  The heating temperature with the addition of a solvent is preferably higher from the viewpoint of the solubility of the cellulose ester, but if the heating temperature is too high, the required pressure increases and the productivity deteriorates. A preferable heating temperature is in the range of 45 to 120 ° C, more preferably in the range of 60 to 110 ° C, and still more preferably in the range of 70 ° C to 105 ° C. The pressure is adjusted so that the solvent does not boil at the set temperature.

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

  Next, this cellulose ester solution is filtered using a suitable filter medium such as filter paper. As the filter medium, it is preferable that the absolute filtration accuracy is small in order to remove insoluble matters and the like, but there is a problem that the filter medium is likely to be clogged if the absolute filtration accuracy is too small. For this reason, a filter medium having an absolute filtration accuracy of 0.008 mm or less is preferable, a filter medium in the range of 0.001 to 0.008 mm is more preferable, and a filter medium in the range of 0.003 to 0.006 mm is more preferable.

  There are no particular restrictions on the material of the filter medium, and ordinary filter media can be used. However, plastic filter media such as polypropylene and Teflon (registered trademark), and metal filter media such as stainless steel do not drop off fibers. preferable. It is preferable to remove and reduce impurities, particularly bright spot foreign matter, contained in the raw material cellulose ester by filtration.

The bright spot foreign matter is placed in a crossed Nicols state with two polarizing plates, a stretched cellulose ester film is placed between them, light is applied from the side of one polarizing plate, and observed from the side of the other polarizing plate. It is a point (foreign matter) where light from the opposite side sometimes leaks, and the number of bright spots having a diameter of 0.01 mm or more is preferably 200 / cm ² or less. More preferably, it is 100 pieces / cm < ² > or less, More preferably, it is 50 pieces / m < ² > or less, More preferably, it is 0-10 pieces / cm < ² > or less. Further, it is preferable that the number of bright spots of 0.01 mm or less is small.

  The dope can be filtered by a normal method, but the method of filtering while heating at a temperature not lower than the boiling point of the solvent at normal pressure and in a range where the solvent does not boil under pressure is the filtration pressure before and after filtration. The increase in the difference (referred to as differential pressure) is small and preferable. A preferable temperature is in the range of 45 to 120 ° C, more preferably in the range of 45 to 70 ° C, and still more preferably in the range of 45 to 55 ° C.

  A smaller filtration pressure is preferred. The filtration pressure is preferably 1.6 MPa or less, more preferably 1.2 MPa or less, and further preferably 1.0 MPa or less.

  Here, the dope casting will be described.

  The metal support in the casting (casting) step preferably has a mirror-finished surface, and a stainless steel belt or a drum whose surface is plated with a casting is preferably used as the metal support. The cast width can be 1 to 4 m. The surface temperature of the metal support in the casting step is −50 ° C. to a temperature lower than the boiling point of the solvent, and a higher temperature is preferable because the web can be dried faster. May deteriorate. The support temperature is preferably in the range of 0 to 40 ° C, more preferably in the range of 5 to 30 ° C. Alternatively, it is also a preferable method that the web is gelled by cooling and peeled from the drum in a state containing a large amount of residual solvent. The method for controlling the temperature of the metal support is not particularly limited, and there are a method of blowing warm air or cold air, and a method of contacting hot water with the back side of the metal support. It is preferable to use warm water because heat transfer is performed efficiently, so that the time until the temperature of the metal support becomes constant is short. When warm air is used, wind at a temperature higher than the target temperature may be used.

  In order for the stretched cellulose ester film to exhibit good flatness, the amount of residual solvent when peeling the web from the metal support is preferably in the range of 10 to 150% by mass, more preferably in the range of 20 to 40% by mass. Or in the range of 60 to 130% by mass, particularly preferably in the range of 20 to 30% by mass or in the range of 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) = {(MN) / N} × 100
Note that M is the mass of a sample collected during or after the production of the web or film, and N is the mass after heating M at 115 ° C. for 1 hour.

  Next, the peeled web is transported to the above-described stretching process (preferably a tenter), the stretching process according to the present invention is performed, and transported to the film drying process as a stretched cellulose ester film.

  In the film drying step, the residual solvent amount 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 process, generally, a roller drying method (a method in which a plurality of rollers arranged above and below are alternately passed through a web for drying) or a tenter method for drying while conveying the web is employed.

  The means for drying the web is not particularly limited, and can be generally performed with hot air, infrared rays, a heating roller, microwaves, or the like, but it is preferably performed with hot air in terms of simplicity.

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

  The preferable drying time depends on the drying temperature, but is preferably in the range of 5 to 60 minutes, and more 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, more preferably in the range of 10 to 100 μm, and still more preferably 30 to 70 μm from the viewpoint of thin film and weight reduction. Within range.

  The stretched cellulose ester film of the present invention has a width in the range of 2 to 4 m, more preferably in the range of 2 to 3 m. If it exceeds 4 m, conveyance becomes difficult.

  The stretched cellulose ester film is preferably heat-set after the above-described stretching treatment, but the heat-setting is preferably heat-set within a temperature range of Tg-20 ° C. or lower and usually within a range of 0.5 to 300 seconds. At this time, it is preferable to perform heat setting while sequentially raising the temperature in a range where the temperature difference is within the range of 1 to 100 ° C. in the region divided into two or more.

  The heat-set film is usually cooled to Tg or less, and clip holding portions at both ends of the film are cut and wound. The cooling is preferably performed by gradually cooling from the final heat setting temperature to Tg at a cooling rate of 100 ° C. or less per second. Means for cooling and relaxation treatment are not particularly limited, and can be performed by a conventionally known means. In particular, it is preferable to carry out these treatments while sequentially cooling in a plurality of temperature ranges from the viewpoint of improving the dimensional stability of the film.

  More optimal conditions of these heat setting conditions, cooling, and relaxation treatment conditions vary depending on the type of additives such as cellulose ester and plasticizer constituting the film, so the physical properties of the obtained stretched film are measured and preferable characteristics are obtained. Thus, it may be determined by adjusting as appropriate.

  The slow axis or the fast axis of the stretched cellulose ester film of the present invention exists in the film plane, and θ1 is preferably −1 ° or more and + 1 ° or less, assuming that the angle formed with the film forming direction is θ1, More preferably, it is 0.5 ° or more and + 0.5 ° or less. This θ1 can be defined as an orientation angle, and θ1 can be measured using an automatic birefringence meter KOBRA-21ADH (Oji Scientific Instruments). Each of θ1 satisfying the above relationship can contribute to obtaining high luminance in a display image, suppressing or preventing light leakage, and contributing to obtaining faithful color reproduction in a color liquid crystal display device.

<Physical properties>
(Refractive index control)
For the stretched cellulose ester film of the present invention, adjusting the retardation by stretching is also an important operation. 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 in the range of 0 to 20 nm, and the retardation value Rt in the thickness direction is in the range of -100 to 100 nm. It is preferable that there are more preferable ranges, and Ro ≦ 5 nm and −30 nm ≦ Rt ≦ 30 nm are preferable.

  In addition, it is also preferable to increase the retardation value for the retardation film by stretching treatment. In that case, the retardation value Ro in the in-plane direction is in the range of 30 to 100 nm, and the retardation value in the thickness direction. 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 is a refractive index in a slow axis direction in the film plane, n _y is the fast axis direction of the refractive index in the film plane, n _z is the thickness direction of the refractive index of the film, d is the film Represents thickness (nm).)
The refractive index can be obtained at a wavelength of 590 nm under an environment of 23 ° C. and 55% RH using, for example, KOBRA-WR (Oji Scientific Instruments).

(Other physical properties)
The moisture permeability of the stretched cellulose ester film of the present invention is preferably in the range of 10 to 1200 g / m ² · 24 h at 40 ° C. and 90% RH, more preferably in the range of 20 to 1000 g / m ² · 24 h. A range of 850 g / m ² · 24 h is particularly preferable. The moisture permeability can be measured according to 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, and more preferably 93% or more.

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

<Polarizing plate>
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.

  The polarizing plate bonds the stretched cellulose ester film of the present invention to at least one surface of the polarizer.

  The polarizing plate can be produced by a general method. The polarizer side of the stretched cellulose ester film of the present invention is preferably bonded to at least one surface of a polarizer prepared by alkali saponification treatment and immersed in an iodine solution using a completely saponified polyvinyl alcohol aqueous solution. . The stretched cellulose ester film may be used on the other surface, or another optical film may be used. Commercially available cellulose ester films (for example, Konica Minoltak KC8UX, KC4UX, KC5UX, KC8UY, KC4UY, KC12UR, KC8UCR-3, KC8UCR-4, KC8UCR-5, KC4FR-1, KC8UK-HA4, UC8UC-UC4 In addition, Konica Minolta Opto Co., Ltd.) is also preferably used.

  For example, when the stretched cellulose ester film of the present invention has a retardation value Ro in the in-plane direction of 0 to 20 nm and a retardation value Rt in the thickness direction of -100 to 100 nm, the liquid crystal cell is used. The optical film used for the opposite polarizing plate has a retardation value Ro in the in-plane direction measured at a wavelength of 590 nm in the range of 20 to 100 nm and a retardation value Rt in the thickness direction in the range of 70 to 300 nm. An optical film having a retardation function is preferred.

  The optical film having the retardation function is not particularly limited, and can be produced, for example, by the methods described in JP-A-2005-196149 and JP-A-2005-275104. Furthermore, it is also preferable to use an optical film that also serves as an optical compensation film having an optically anisotropic layer formed by aligning a liquid crystal compound such as a discotic liquid crystal. For example, the optically anisotropic layer can be formed by the method described in JP-A-2005-275083. By using the optical film having the retardation function in combination, a polarizing plate and a liquid crystal display device having a stable viewing angle expansion effect can be obtained.

  A polarizer, which is a main component of a polarizing plate, is an element that allows only light of a plane of polarization in a certain direction to pass. A typical polarizer currently known is a polyvinyl alcohol-based polarizing film, which is polyvinyl alcohol. There are one in which iodine is dyed on a system film and one in which dichroic dye is dyed. For the polarizer, a polyvinyl alcohol aqueous solution is formed into a film and dyed by uniaxial stretching or dyed or uniaxially stretched and then preferably subjected to a durability treatment with a boron compound. The film thickness of the polarizer is preferably in the range of 5 to 30 μm, and particularly preferably in the range of 10 to 20 μm.

  Further, the content of the ethylene unit described in JP-A-2003-248123, JP-A-2003-342322, etc. is in the range of 1 to 4 mol%, the polymerization degree is in the range of 2000 to 4000, and saponification is performed. Ethylene-modified polyvinyl alcohol having a degree of 99.0 to 99.99 mol% is also preferably used. Among these, an ethylene-modified polyvinyl alcohol film having a hot water cutting temperature in the range of 66 to 73 ° C. is preferably used. The difference in hot water cutting temperature between two points 5 cm away in the TD direction of the film is more preferably 1 ° C. or less to reduce color spots, and two points 1 cm away in the TD direction of the film. In order to reduce color spots, it is more preferable that the difference in the hot water cutting temperature is 0.5 ° C. or less.

  A polarizer using this ethylene-modified polyvinyl alcohol film is excellent in polarization performance and durability, and has few color spots, and is particularly preferably used for a large-sized liquid crystal display device.

  The polarizer obtained as described above is generally used as a polarizing plate with a protective film pasted on both sides or one side thereof. As an adhesive used for pasting, a PVA-based adhesive is used. In particular, a PVA-based adhesive is preferably used.

<Liquid crystal display device>
By incorporating the polarizing plate into the display device, various liquid crystal display devices with excellent visibility can be manufactured. As the liquid crystal display device, a reflection type, a transmission type, a semi-transmission type liquid crystal display device, or a liquid crystal display device of various drive systems such as a TN type, STN type, OCB type, VA type, IPS type, ECB type, particularly VA type. It is preferably applied to a liquid crystal display device of (MVA type, PVA type).

  Since the stretched cellulose ester film of the present invention has a small variation in the width direction of the retardation value Ro in the in-plane direction, the polarizing plate using the film has visibility even when used in a large-screen liquid crystal display device. Good and excellent front contrast can be imparted.

  A large-screen liquid crystal display device having a 17-inch or larger screen, especially a 30-inch or larger screen has an effect that eyes are not tired even during long-time viewing because there is no distortion such as color unevenness and wavy unevenness.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

Example 1
<Preparation of stretched cellulose ester film 1>
<Fine particle dispersion 1>
Fine particles (Aerosil R812V manufactured by Nippon Aerosil Co., Ltd.) 11 parts by weight Ethanol 89 parts by weight The above was stirred and mixed with a dissolver for 50 minutes, and then dispersed with Manton Gorin.

<Fine particle addition liquid 1>
The fine particle dispersion 1 was slowly added to the dissolution tank containing methylene chloride with sufficient stirring. Further, the particles were dispersed by an attritor so that the secondary particles had a predetermined particle size. This was filtered through Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle additive solution 1.

Methylene chloride 99 parts by mass Fine particle dispersion 1 5 parts by mass A main dope having the following composition was prepared. First, methylene chloride and ethanol were added to the pressure dissolution tank. Cellulose acetate having an acetyl group substitution degree of 2.60 was added to a pressurized dissolution tank containing a solvent while stirring. This is completely dissolved with heating and stirring. This was designated as Azumi Filter Paper No. The main dope was prepared by filtration using 244.

<Composition of main dope>
Methylene chloride 550 parts by mass Ethanol 40 parts by mass Cellulose acetate (acetyl group substitution degree 2.60, weight average molecular weight 260000)
100 parts by mass Triphenyl phosphate 10 parts by mass Ethylphthalylethyl glycolate 5 parts by mass Fine particle additive 1 5 parts by mass Tinuvin 928 (manufactured by BASF Japan) 2.6 parts by mass A dope was prepared. Next, using an endless belt casting apparatus, the dope was cast at a temperature of 33 ° C. and a width of 1600 mm so as to have a uniform film thickness on a stainless belt support. The temperature of the stainless steel belt was controlled at 30 ° C.

  On the stainless steel belt support, the solvent was evaporated until the residual solvent amount in the cast (cast) film was 75%, and then peeled off from the stainless steel belt support with a peeling tension of 130 N / m.

  The peeled cellulose acetate film is stretched at a stretch ratio of 35% in the width direction by adjusting the temperature of the housing 10 using the tenter shown in FIG. did.

  The surface temperature of the film edge and center is measured at 5 points for the width direction of the film being transported using a contact-type handy thermometer (ANRITSU DIGITAL THREMOMETER HA-100K), and the average value is measured. The surface temperature of the part was used.

  Next, drying was completed while the drying zone was conveyed at a high speed with a large number of rollers, and after slitting at the end so as to obtain a desired product width, winding was performed. The drying temperature was 130 ° C. and the transport 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.

  The film thickness of the finished stretched cellulose ester film 1 is determined by measuring the thickness of the stretched cellulose ester film 1 from the edge in the width direction using a contact-type film thickness meter (manufactured by Tokyo Seimitsu Co., Ltd .: Micrometer Minicom M). The film thickness difference h (maximum film thickness-edge film thickness) was determined to be 0.5 μm. Moreover, when it was judged by the regression formula whether it was represented with a suspension curve from the said film thickness measurement value, it was not represented with the suspension curve.

<Preparation of stretched cellulose ester film 2>
In the production of the stretched cellulose ester film 1, the dope was cast at a temperature of 33 ° C. and a width of 2400 mm so as to obtain a uniform film thickness on the stainless steel belt support, and the stretched film width was 2300 mm. Cellulose ester film 2 was produced.

  The film thickness of the finished stretched cellulose ester film 1 is determined by measuring the thickness of the stretched cellulose ester film 1 from the edge in the width direction using a contact-type film thickness meter (manufactured by Tokyo Seimitsu Co., Ltd .: Micrometer Minicom M). The film thickness difference h (maximum film thickness-edge film thickness) was determined to be 0.5 μm. Moreover, when it was judged by the regression formula whether it was represented with a suspension curve from the said film thickness measurement value, it was not represented with the suspension curve.

<Preparation of stretched cellulose ester film 3>
In the production of the stretched cellulose ester film 2, when the dope is cast on the stainless steel belt support through the slit gap of the die die, the central part is thicker than the end part so that the film thickness approximates the suspension curve. A stretched cellulose ester film 3 was produced in the same manner except that the film was cast.

  The film thickness of the finished stretched cellulose ester film 3 is obtained by measuring the thickness of the stretched cellulose ester film 3 at intervals of 10 cm from the end in the width direction using a contact-type film thickness meter (manufactured by Tokyo Seimitsu Co., Ltd .: Micrometer Minicom M). When the film thickness difference h (maximum film thickness−edge film thickness) was determined, it was 1.5 μm. Moreover, when it was judged from the above-mentioned film thickness measurement value by a regression equation whether or not it was represented by a suspension curve, it was represented by a suspension curve.

<Preparation of stretched cellulose ester film 4>
The composition of the main dope was changed as follows.

<Composition of main dope>
Methylene chloride 550 parts by mass Ethanol 40 parts by mass Cellulose acetate (acetyl group substitution degree 2.85, weight average molecular weight 270000)
100 parts by mass Sugar ester plasticizer (Exemplary compound 1-7) 8 parts by mass Aromatic terminal ester plasticizer (Exemplary compound 2-16) 5 parts by mass Fine particle additive 1 5 parts by mass Tinuvin 928 (manufactured by BASF Japan) 2.6 parts by mass When the dope is cast on the stainless steel belt support through the slit gap of the die die in the same manner as in the production of the stretched cellulose ester film 3, the film thickness is compared with the end part so as to approximate a suspension curve. The film was cast so that the central portion was thick, and a stretched cellulose ester film 4 was produced under the conditions shown in Table 2.

  The film thickness of the finished stretched cellulose ester film 4 is determined by measuring the thickness of the stretched cellulose ester film 4 from the end in the width direction using a contact-type film thickness meter (manufactured by Tokyo Seimitsu Co., Ltd .: Micrometer Minicom M). When the film thickness difference h (maximum film thickness−edge film thickness) was determined, it was 1.5 μm. Moreover, when it was judged from the above-mentioned film thickness measurement value by a regression equation whether or not it was represented by a suspension curve, it was represented by a suspension curve.

<Production of stretched cellulose ester films 5 and 6>
In the production of the stretched cellulose ester film 4, the stretched cellulose ester film 5 and the film thickness of the center part and the end part were adjusted in the same manner except changing the slit gap of the die die so as to satisfy the conditions described in Table 2. 6 was produced.

  The film thicknesses of the finished stretched cellulose ester films 5 and 6 were determined by measuring them at 10 cm intervals in the width direction from the end using a contact-type film thickness meter (manufactured by Tokyo Seimitsu Co., Ltd .: Micrometer Minicom M). When the film thickness difference h (maximum film thickness-edge film thickness) was determined from the values, the values shown in Table 2 were obtained. Moreover, when it was judged from the above-mentioned film thickness measurement value by a regression equation whether or not it was represented by a suspension curve, it was represented by a suspension curve.

<Preparation of stretched cellulose ester film 7>
In preparation of the stretched cellulose ester film 4, the peeled unstretched cellulose acetate film is adjusted to adjust the temperature of the housing 10 using the tenter shown in FIG. Further, an end cold air generating portion G1 is installed at the position shown in FIG. 5, and the film is stretched in the width direction by 45% while adjusting the temperature so that the stretching temperature of the film end surface is 155 ° C. Was made.

  The film thickness of the finished stretched cellulose ester film 7 is determined by measuring at 10 cm intervals in the width direction from the end using a contact-type film thickness meter (manufactured by Tokyo Seimitsu Co., Ltd .: Micrometer Minicom M). When the film thickness difference h (maximum film thickness-edge film thickness) was determined, the values shown in Table 2 were obtained. Moreover, when it was judged from the above-mentioned film thickness measurement value by a regression equation whether or not it was represented by a suspension curve, it was represented by a suspension curve.

<Production of stretched cellulose ester films 8-12>
In the production of the stretched cellulose ester film 7, the stretched cellulose ester film was similarly performed except that the cellulose ester acetyl group substitution degree, the maximum film thickness, the film end film thickness, the finished width, and the stretching temperature were changed as shown in Table 2. 8-12 were produced.

  The thickness of the finished stretched cellulose ester films 8 to 12 is determined by measuring the thickness of the stretched cellulose ester films 8 to 12 from the end in the width direction using a contact-type film thickness meter (manufactured by Tokyo Seimitsu Co., Ltd .: Micrometer Minicom M). When the film thickness difference h (maximum film thickness-edge film thickness) was determined from the values, the values shown in Table 2 were obtained. Moreover, when it was judged from the above-mentioned film thickness measurement value by a regression equation whether or not it was represented by a suspension curve, it was represented by a suspension curve.

<Preparation of stretched cellulose ester film 13>
In the production of the stretched cellulose ester film 9, the end cold air generating portion G1 shown in FIG. 5 is installed only in the center portion, and the stretch is performed so that the temperature of the center portion is 30 ° C. lower than the end portion. Thus, a stretched cellulose ester film 13 was produced.

  The film thickness of the finished stretched cellulose ester film 13 is determined by measuring at 10 cm intervals in the width direction from the end using a contact-type film thickness meter (manufactured by Tokyo Seimitsu Co., Ltd .: Micrometer Minicom M). The film thickness difference h (maximum film thickness-edge film thickness) was determined to be 5.3 μm. Moreover, when it was judged by the regression formula whether it was represented with a suspension curve from the said film thickness measurement value, it was not represented with the suspension curve.

<Evaluation>
The following evaluation was implemented about the produced stretched cellulose-ester films 1-13.

(Measurement of arithmetic average roughness (Ra))
The average value of the arithmetic average roughness (Ra) at the edge is selected in the longitudinal direction for the film edge (area H in FIG. 3), and the arithmetic average roughness (Ra) is measured for each to determine the average value. It was.

  The average value of the arithmetic average roughness (Ra) of the central part was selected in the longitudinal direction with respect to the central part (area T in FIG. 3), and each arithmetic average roughness (Ra) was measured to obtain the average value. .

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

(Slit suitability for high-speed conveyance)
The suitability for slitting during high-speed conveyance was evaluated under the following criteria, which was performed under a high-speed condition with a conveyance speed 1.3 times the film conveyance speed under the standard conditions.

◎: No ear-cutting defect occurs when transported at high speed ○: Ear-cutting defect hardly occurs when transported at high speed △: Ear-cutting defect occurs frequently when transported at high speed ×: High-speed transport When this is done, the ear-cutting defect frequently breaks and the practically acceptable range is ◯ or more.

(Ro variation)
Ten samples were collected from each end and center of the produced stretched cellulose ester film, and the wavelength was 23 ° C. and 55% RH using KOBRA-WR (Oji Scientific Instruments). The retardation value Ro in the in-plane direction was measured at 590 nm, and the average values of the retardation values Ro at the central part and the edge part were respectively determined. Subsequently, the difference was evaluated according to the following evaluation criteria.

Formula _{(i) Ro = (n x} -n y) × d
(Wherein, n _x is a refractive index in a slow axis direction in the film plane, n _y is the fast axis direction of the refractive index in the film plane, d represents the thickness of the film (nm).)
A: The difference between (center part to end part) is less than 0.5 nm B: The difference between (center part to end part) is 0.5 nm or more and less than 1.0 nm C: The difference between (center part to end part) is 1. 0 nm or more and less than 2.0 nm D: The difference of (center part to end part) is 2.0 nm or more. The practical allowable range is B or more.

  Tables 2 and 3 show the structures and evaluation results of the above stretched cellulose ester films.

  From the results in Tables 2 and 3, the stretched cellulose ester film of the present invention is superior to the stretched cellulose ester film of the comparative example in terms of slit suitability during high-speed conveyance even when widened, and the surface of the center and end It was found that the dispersion of the retardation value Ro in the inward direction was small, and thus the optical characteristics were excellent.

Example 2
<Preparation of polarizing plate>
The produced stretched cellulose ester films 1 to 13 were alkali-treated with a 2.5 mol / L sodium hydroxide aqueous solution at 40 ° C. for 60 seconds, washed with water for 3 minutes and saponified to obtain an alkali-treated film.

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

  Next, using a fully saponified polyvinyl alcohol 5% aqueous solution as an adhesive, stretched cellulose ester films 1 to 13 were bonded to both sides of the polarizer to prepare polarizing plates 1 to 13, respectively.

(Production of liquid crystal display device)
A liquid crystal panel for viewing angle measurement was produced as follows, and the characteristics as a liquid crystal display device were evaluated.

  The polarizing plate on the viewing side of the 40-inch display KLV-40J3000 made by SONY, which is a VA mode type liquid crystal display device, was peeled off from the viewing side, and the polarizing plates 1 to 13 prepared above so that the absorption axes of the polarizing plates were matched. Was bonded to the glass surface of the liquid crystal cell to produce a VA mode type liquid crystal display device, and color unevenness and front contrast were visually evaluated.

  As a result, the polarizing plate using the stretched cellulose ester film of the present invention, the liquid crystal display device has a small variation in the in-plane retardation value Ro, so that there is no color unevenness, and the polarizing plate has excellent front contrast, It was found to be a liquid crystal display device.

  Even if the stretched cellulose ester film of the present invention is stretched at a high magnification to be widened, the disorder of cellulose orientation is suppressed, and even when transported at a high speed, ear-cutting failure hardly occurs, and the retardation value Ro in the in-plane direction is low. The film has a small variation in each part of the film, and can be suitably used for a polarizing plate protective film and an optical film for a liquid crystal display device.

A A surface B B surface Mh Maximum film thickness Lh Terminal film thickness K Suspension curve W, Fo Unstretched cellulose ester film (web)
F Stretched cellulose ester film 1 Stainless steel endless belt (support)
3 Peeling roller 4 Tenter 5 Drying device 6 Conveying roller 8 Winding roller 10 Housing 11 Clip 12 Rail G1, G2 End cold air generating part

Claims (6)

A stretched cellulose ester film acetyl group substitution degree containing cellulose ester is in the range of 2.8 to 2.95, part of the cross-sectional shape in one of the width direction of the front surface of the stretched cellulose ester film Is a suspended curve, and the film thickness difference h (maximum film thickness−film end film thickness) is in the range of 1.0 to 4.0 μm . Wherein in the range average of 2.2~3.5nm stretching one central arithmetic average roughness of the front surface of the cellulose ester film (Ra), the end on one front surface of the stretched cellulose ester film The stretched cellulose ester film according to claim 1, wherein the stretched cellulose ester film is 0.3 to 1.0 nm higher than an average value of arithmetic average roughness (Ra) of a part.
Here, when the total width of the stretched cellulose ester film is defined as L, the end portion refers to the end of the film to L × 0.05, and the central portion refers to the total width of the stretched cellulose ester film as L. Sometimes, it means a portion of ± L × 0.1 in the width direction from the center of the film.   The stretched cellulose ester film according to claim 1 or 2, wherein the stretched cellulose ester film has a width of 2 to 3 m and a maximum film thickness of 30 to 70 µm. It is a manufacturing method of the stretched cellulose-ester film of any one of Claims 1-3, Comprising: The dope which forms this stretched-cellulose-ester film has a part of cross-sectional shape in the width direction of the film A surface suspended. As shown by the curve, a web is formed by casting on a belt or a drum, and after peeling, the surface temperature of the end of the web A is within the range of 10 to 50 ° C. compared to the surface temperature of the center. The manufacturing method of the stretched cellulose-ester film characterized by extending | stretching, reducing.
Here, the surface A refers to the surface opposite to the side in contact with the belt surface or drum surface when cast on a belt or drum to form a film dope.
Here, when the total width of the unstretched cellulose ester film is Lo, the end portion refers to the end of the film to Lo × 0.05, and the central portion is the total width of the unstretched cellulose ester film. , A portion of ± Lo × 0.1 in the width direction from the center of the film.   In order to adjust the surface temperature of the end portion, at least a pair of end cold air generating portions are provided, and cool air having a temperature lower than the temperature of the central portion is lower than the temperature of the central portion than the end cold air generating portion. The method for producing a stretched cellulose ester film according to claim 4, wherein the stretch treatment is performed while spraying the end portion.   6. The film according to claim 4, wherein the film is stretched in the width direction of the film at a stretching ratio in a range of 160 to 190 ° C. and in a range of 25 to 100%. The manufacturing method of the stretched cellulose-ester film of description.

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