JP2007185945A - Cellulosic resin film, its manufacturing method and film product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a cellulosic resin film suppressed in the fluctuations of a film thickness distribution in its longitudinal direction and also reduced in the occurrence of die streaks. <P>SOLUTION: Molten cellulose acylate is discharged from a die 14 to be formed into a cellulose acylate sheet 26. Infrared heaters 15 and 16 are provided to the air gap H where the sheet 26 from the die 14 is cast on a casting drum 17. The air gap H is set to 50 mm and the heating temperature of the sheet 26 by the infrared heaters 15 and 16 is set to 300°C. By adjusting the temperature of the sheet 26 at a casting position 17a to 235°C, the levelling effect of the sheet 26 on the drum is developed and the surface of the sheet 26 becomes almost uniform and the film thickness distribution and die streaks of the obtained film are reduced. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cellulose resin film, a method for producing the same, and a film product, and more particularly to a cellulose resin film such as a cellulose acylate film preferably used for a liquid crystal display device, a method for producing the same, and a film product for a liquid crystal display device. It is.

Cellulose-based resin films such as cellulose acylate films are melted with an extruder and extruded into a die, and the molten cellulose-based resin is discharged into a sheet form from the die outlet and solidified by cooling (melted product). Called the membrane method). Then, as a film having desired in-plane retardation (Re) and thickness retardation (Rth) by stretching in at least one of longitudinal (longitudinal direction; MD) and lateral (width direction; TD). can get. This film is used for an optical compensation film (also referred to as a retardation film) of a liquid crystal display device and the like, and the viewing angle is increased (for example, see Patent Document 1).
Japanese National Patent Publication No. 6-501040

  However, in the conventional melt film-forming method, the sheet-like molten cellulose resin discharged from the die starts to cool and solidify before reaching the casting drum. Therefore, the sheet-like resin that has reached the casting drum has a problem that it is difficult to exhibit a leveling effect of smoothing the flat surface. Therefore, there is a problem that a film thickness distribution is generated in the obtained film, and a streak (also referred to as a die streak) generated when the film is discharged from the die remains.

  Therefore, an object of the present invention is to control the film thickness distribution in the longitudinal direction of the film within a certain range and to suppress the remaining of die stripes generated when the molten resin is discharged from the die.

  In order to achieve the above object, the invention of claim 1 is a method for producing a cellulose-based resin film, in which a film is produced by casting a sheet-like cellulose-based resin obtained by discharging a molten cellulose-based resin from a die into a sheet to a drum The film thickness distribution of the cast sheet-like cellulose resin is within 5 μm per 10 m with respect to the longitudinal direction of the film, and the maximum of the stripe depth on at least one surface of the sheet-like cellulose resin is The value is 1 μm or less. According to claim 1, since a film having excellent surface smoothness can be obtained, it can be preferably used as a base film for various film products.

  In order to achieve the above object, the invention according to claim 2 is a method for producing a cellulose resin film in which a melted cellulose resin is discharged from a die into a sheet and cast onto a drum to produce a film. The temperature at the casting position of the sheet-like cellulose resin is maintained in a temperature range of 150 ° C. or higher and 230 ° C. or lower. According to the second aspect, since the sheet-like cellulose resin discharged from the die is heated until it is cast on the casting drum, the viscosity of the sheet-like cellulose resin can be adjusted. Therefore, the sheet-like cellulosic resin is likely to exhibit surface smoothing (leveling effect) due to its surface tension on the casting drum, and a cellulose-based resin film having a small film thickness distribution (thickness unevenness) can be obtained. it can.

  In the invention of claim 3, it is preferable that the temperature decrease until the sheet-like cellulose resin discharged from the die is cast to the drum is within 20 ° C.

  In the invention of claim 4, the sheet-like cellulose resin is in a range of (solid phase-solid phase transition temperature + 50) ° C. or more (solid phase-solid phase transition temperature + 250) ° C. of the cellulose resin. It is preferable to heat.

  In the invention of claim 5, the solid phase-solid phase transition temperature is preferably the glass transition temperature Tg (° C.) of the cellulose resin.

  In invention of Claim 6, it is preferable to heat the said sheet-like cellulose resin with a heater.

  In the invention of claim 7, the distance L1 (mm) between at least one surface of the sheet-like cellulose resin and the surface of the first heater disposed on the one surface side is 10 mm or more and 150 mm or less. Is preferred.

  In the invention of claim 8, it is preferable that a length H1 (mm) in a casting direction in which the first heater heats the sheet-like cellulose resin is 5 mm or more and 300 mm or less.

  In a ninth aspect of the present invention, it is preferable that a second heater is further disposed on a surface opposite to the one surface of the sheet-like cellulose resin.

  In a tenth aspect of the present invention, a distance L2 (mm) between the opposite side surface of the sheet-like cellulose resin and the surface of the second heater is preferably 10 mm or more and 150 mm or less.

  In an eleventh aspect of the invention, it is preferable that a length H2 (mm) in a casting direction in which the second heater heats the sheet-like cellulose resin is 5 mm or more and 300 mm or less.

  In the invention of claim 12, it is preferable that the heater emits an electromagnetic wave of 0.7 μm or more and 1000 μm or less to heat the sheet-like cellulose resin. According to the twelfth aspect, since the heating of the sheet-like cellulose resin is performed by a heater, more preferably an electromagnetic wave emission type heater, the occurrence of thickness fluctuations such as unevenness on the surface of the sheet-like cellulose resin is suppressed. . Furthermore, since the wavelength of the electromagnetic wave emitted by the electromagnetic wave emission type heater is 0.7 μm or more and 1000 μm or less, there is no adverse effect such as decomposing the cellulose compound constituting the cellulose resin.

  In invention of Claim 13, when the said sheet-like cellulose resin is cast on the said drum, it is preferable to level the said sheet-like cellulose resin on the surface of the said drum.

  In the invention of claim 14, it is preferable to use a drum having an arithmetic mean roughness (Ra) of the surface of the drum of 0.3 μm or less. According to the fourteenth aspect, the arithmetic average roughness (Ra) of the surface of the casting drum has a roller contact surface side of the cellulose resin film obtained by using a casting drum (roller) of 0.3 μm or less. The film thickness distribution (thickness unevenness) can be reduced.

  The invention according to claim 15 is a method of casting the sheet-like cellulosic resin between two drums, wherein the other drum of the sheet-like cellulosic resin is adjusted by adjusting the position of one drum. It is preferable that the landing point is a substantially constant position.

  In the invention of claim 16, when the viscosity of the sheet-like cellulose resin is measured by the Capillati rheometer method at 25 ° C. and 60% RH, it may be set to 100 Pa · s or more and 2000 Pa · s or less. preferable. According to the sixteenth aspect, the leveling effect after casting is easily exhibited by setting the viscosity of the sheet-like cellulose resin in the above range.

  The invention according to claim 17 is a cellulose resin film produced by the method for producing a cellulose resin film according to any one of claims 1 to 16. The inventions of claims 18 to 20 are a polarizing plate, an optical compensation film, and an antireflection film, characterized in that the cellulose resin film of claim 17 is used.

  According to the present invention, it is possible to control the film thickness distribution in the longitudinal direction of the film within a certain range, and to reduce the residual die streaks that occur when the molten resin is discharged from the die.

  A preferred embodiment of the method for producing a cellulose resin film according to the present invention will be described. In this embodiment, an example of producing a cellulose acylate film is shown, but the present invention is not limited to this, and is also applicable to production of a film using a cellulose-based resin other than cellulose acylate as a raw material. it can.

  FIG. 1 shows an example of a schematic configuration of a cellulose acylate film production line 10. The production line 10 includes an extruder 11, a gear pump 12, a pipe 13, a die 14, heaters 15 and 16, drums 17, 18 and 19, a position adjusting drum 20, a roller 31 and a winder 35.

  The gear pump 12 is preferably used as an apparatus (pump) for supplying the film raw material 25 mainly composed of cellulose acylate to the production line. The gear pump 12 does not change the specific extrusion amount even when the extrusion pressure increases. Therefore, there is an advantage that the temperature rise of the extruded polymer due to shear heat generation is small. Further, since the shear heat generation is small even when the gear rotation speed is increased, an increase in the extrusion temperature is suppressed accordingly. Therefore, the specific extrusion amount does not change, and the film raw material 25 can be stably supplied to the production line 10. Thus, deterioration due to thermal decomposition or the like of cellulose acylate that is weak against heat (for example, the thermal decomposition temperature of cellulose acylate propionate (CAP), which is a typical example of cellulose acylate) is about 250 ° C. It can be suppressed.

  The film raw material 25 is supplied from a hopper (not shown) to the extruder 11 and melted in the extruder 11 to become a fluid (hereinafter referred to as molten cellulose acylate). The extrusion temperature from the extruder 11 is preferably 190 ° C. or higher and 240 ° C. or lower, more preferably 195 ° C. or higher and 235 ° C. or lower, and particularly preferably 200 ° C. or higher and 230 ° C. or lower. When the extrusion temperature is lower than 190 ° C., the cellulose acylate crystals may be insufficiently melted. Therefore, fine crystals are likely to remain in the obtained cellulose acylate film. Even if the cellulose acylate film is stretched, the stretchability is hindered, and the orientation of the cellulose acylate molecules cannot be sufficiently controlled, and desired retardation values (Re and Rth) may not be obtained. In some cases, the problem of film breakage also occurs. Moreover, when extrusion temperature exceeds 240 degreeC, there exists a possibility that degradation, such as thermal decomposition, may arise in a cellulose acylate. A film obtained from deteriorated cellulose acylate may deteriorate in yellowness (YI value).

  The molten cellulose acylate is fed by the gear pump 12 and passes through the pipe 13 before being sent to the die 14. In addition, it is preferable that a temperature control device (not shown) is attached to the pipe 13 and maintained at a predetermined temperature. The molten cellulose acylate is discharged from the die 14 into a sheet (hereinafter referred to as a cellulose acylate sheet 26) and cast on a drum (hereinafter referred to as a casting drum) 17. A touch roll method in which a position adjusting drum 20 is provided opposite to the casting drum 17 shown in FIG. 1 and casting between the drums 17 and 20 may be performed in the present invention. A position adjusting device 40 is attached to the position adjusting drum 20. Cooling drums (hereinafter referred to as cooling drums) 18 and 19 are provided downstream of the casting drum 17.

  Although FIG. 1 shows an example in which two cooling drums 18 and 19 are arranged, the number of cooling drums arranged in the present invention is not limited to two. In addition, it is preferable that the cooling device 41 is connected to each of the drums 17 to 19 to independently control the temperature of each of the drums 17 to 19. Although the temperature of each drum 17-19 is not specifically limited, It is preferable that the temperature of the drum 17 for casting is 45 degreeC or more and 160 degrees C or less, and the temperature of the drums 18 and 19 for cooling is 60 degreeC or more and 150 degreeC. The following is preferable. The cellulose acylate sheet 26 is cooled on the surface of each drum 17-19. Hereinafter, the cooled cellulose acylate sheet 26 is referred to as a cellulose acylate film 27.

  Then, the cellulose acylate film 27 is sent to the cooling zone 30 and conveyed while being wound around the roller 31 to be further cooled. The cooling zone 30 is preferably provided with a temperature adjusting device 32, and the temperature of the cooling zone 30 is preferably 20 ° C. or higher and 70 ° C. or lower. Further, the cooling zone may be divided into a plurality of sections, and the temperature may be adjusted for each section.

  The cellulose acylate film 27 adjusted to a desired temperature (for example, 25 ° C. or more and 40 ° C. or less) in the cooling zone 30 is wound up in a roll shape by a winder 35. In the present invention, the film forming speed of the cellulose acylate film 27 is not particularly limited, but is preferably 3 m / min or more and 200 m / min or less, more preferably 10 m / min or more and 150 m / min or less. Most preferably, it is 20 m / min or more and 100 m / min or less. In addition, the method for producing a cellulose resin film according to the present invention is preferably applied to a film having an average film thickness of 60 μm to 120 μm, more preferably 70 μm to 110 μm, and most preferably. Is to be applied to those of 80 μm or more and 100 μm or less.

  In the present invention, the viscosity of the cellulose acylate sheet 26 can be kept within a certain range by keeping the temperature of the cellulose acylate sheet 26 within a certain temperature. As a result, a leveling effect is exhibited in the cellulose acylate sheet 26 on the casting drum 17 and the cooling drums 18 and 19. Due to the leveling effect, the film thickness distribution is within 5 μm per 10 m in the longitudinal direction (film forming direction) of the cellulose acylate film 27 obtained, within 3 μm by selecting more conditions, and within 1 μm by selecting the most conditions. It becomes. Further, if the cellulose acylate sheet 26 having a low viscosity is also used as a streak (also referred to as a die streak) generated when the molten cellulose acylate is discharged from the die 14, the leveling effect is easily exhibited. Get smaller. According to the conditions of the present invention, the maximum value of streaks is 1 μm or less, 0.5 μm or less is selected by selecting more conditions, and 0.3 μm or less is selected by selecting the most conditions.

  FIG. 2 shows an enlarged view of a main part of the production line 10. In FIG. 2, the position adjusting drum 20 can be omitted. In the present invention, the temperature T1 (° C .; starting point temperature) of the cellulose acylate sheet 26 at the die discharge port 14a and the temperature T2 (° C .; end point temperature) of the cellulose acylate sheet 26 at the position 17a cast to the casting drum 17 are used. It is important that the temperature is within the desired temperature range. That is, the starting point temperature T1 is preferably 150 ° C. or higher and 250 ° C. or lower, more preferably 170 ° C. or higher and 240 ° C. or lower, and most preferably 190 ° C. or higher and 230 ° C. or lower. The end point temperature T2 is preferably 130 ° C. or higher and 240 ° C. or lower, more preferably 150 ° C. or higher and 230 ° C. or lower, and most preferably 170 ° C. or higher and 220 ° C. or lower. By maintaining the temperature of the cellulose acylate sheet 26 in the above range, it is possible to suppress the occurrence of die streaks in the molten cellulose acylate at the die discharge port 14a and to easily develop the leveling effect on the casting drum 17. . More preferably, the decrease temperature ΔT (° C.; = Starting temperature T1−ending temperature T2) is preferably within 20 ° C., more preferably within 10 ° C., and most preferably within 5 ° C.

  In addition, the temperature (starting point temperature T1 and end point temperature T2) of the cellulose acylate sheet 26 can also be based on the solid phase-solid phase transition temperature of the cellulose acylate. For example, it is preferably (solid phase-solid phase transition temperature + 50) ° C. or higher (solid phase-solid phase transition temperature + 250) ° C. or lower, more preferably (solid phase-solid phase transition temperature + 70) ° C. or higher (solid phase −Solid phase transition temperature + 230) ° C. or lower, most preferably (solid phase−solid phase transition temperature + 90) ° C. or higher and (solid phase−solid phase transition temperature + 220) ° C. or lower. Examples of the solid-solid phase transition temperature include a glass transition temperature.

  In the present invention, the measurement of the start point temperature T1 and the end point temperature T2 is performed using non-contact type thermometers 45 and 46 provided in the vicinity of the die discharge port 14a and the cast position 17a, respectively. The non-contact type thermometers 45 and 46 are not particularly limited, but it is preferable to use a thermovision or the like.

  The means for maintaining the start point temperature T1 and the end point temperature T2 of the cellulose acylate sheet 26 in the above range is not particularly limited, but it is preferable to use heaters 15 and 16, more preferably an infrared heater. . A heater that emits an electromagnetic wave of 0.7 μm or more and 1000 μm or less is preferable so that an electromagnetic wave emitted from the infrared heater does not affect the cellulose acylate molecule, and more preferably 4 μm or more and 1000 μm or less.

  The heater is provided only on one side of the cellulose acylate sheet casting drum contact side surface (hereinafter referred to as contact surface) heater 15 and the casting drum non-contact side surface (hereinafter referred to as non-contact surface) heater 16. It may be provided on both sides. The distance L1 (mm) between the contact surface side cellulose acylate sheet 26 and the surface of the contact surface side heater 15 is preferably 3 mm or more and 300 mm or less, more preferably 5 mm or more and 200 mm or less, and most preferably 10 mm or more. It is 150 mm or less.

  Further, the distance L2 (mm) between the cellulose acylate sheet 26 on the non-contact surface side and the surface of the non-contact surface side heater 16 is preferably 3 mm or more and 300 mm or less, more preferably 5 mm or more and 200 mm or less, Most preferably, it is 10 mm or more and 150 mm or less.

  Further, the length H1 (mm) at which the contact surface side heater 15 heats the cellulose acylate sheet 26 and the length H2 (mm) at which the non-contact surface side heater 16 heats the cellulose acylate sheet 26 are both 1 mm to 500 mm. Or less, more preferably 3 mm or more and 400 mm or less, and most preferably 5 mm or more and 300 mm or less.

  The cellulose acylate sheet 26 cast on the casting roller 17 exhibits a leveling effect in which the surface is smoothed by the surface tension. In order to preferably exhibit the leveling effect, the viscosity of the cellulose acylate sheet 26 is preferably in the range of 100 Pa · s to 2000 Pa · s, more preferably 300 Pa · s to 1500 Pa · s, most preferably Is 500 Pa · s or more and 1000 Pa · s or less. It is important in the present invention that the cellulose acylate sheet 26 is heated by the heaters 15 and 16 so that the viscosity of the cellulose acylate sheet 26 falls within the above range. In the present invention, the viscosity of the cellulose acylate sheet 26 is a value measured by a Capillary rheometer method at 25 ° C. and 60% RH.

  The arithmetic average roughness (Ra) of the surface of the casting drum 17 is preferably 0.3 μm or less, more preferably 0.1 μm or less, and most preferably 0.05 μm or less. Further, the lower limit value of the arithmetic average roughness (Ra) is not particularly limited, but it is very expensive to produce a drum having a very small roughness. Therefore, if it is 0.05 micrometer or more, a problem will not arise in particular in the influence on the expression of the leveling effect in this invention.

  In the present invention, it is preferable that the cast position 17a of the cellulose acylate sheet 26 is substantially constant. For this reason, it is preferable to provide a device that keeps the cast position constant. 1 and 2 show a form in which the position adjusting drum 20 is provided at a position facing the casting drum 17 (touch roll method). A position adjusting device 40 is attached to the position adjusting drum 20. When it is found by a cast position detector (not shown) that the cast position 17a of the cellulose acylate sheet 26 has changed, the position adjusting device 40 is activated to move the position adjusting drum 20 to a desired position, so that the cast position 17a is omitted. Adjust so that the position is constant.

  The wound cellulose acylate film can be stretched as described later. The cellulose acylate film is stretched in order to orient the molecules in the cellulose acylate film and develop in-plane retardation (Re) and thickness direction retardation (Rth). Here, the retardations Re and Rth are obtained by the following equations.

Re (nm) = | n (MD) −n (TD) | × T (nm)
Rth (nm) = | {(n (MD) + n (TD)) / 2} −n (TH) | × T (nm)
N (MD), n (TD), and n (TH) in the formula indicate the refractive index in the longitudinal direction, the width direction, and the thickness direction, and T indicates the thickness of the film expressed in nm.

  The cellulose acylate film is first longitudinally stretched in the longitudinal direction in the longitudinal stretching step. In the longitudinal stretching step, after the cellulose acylate film is preheated, the cellulose acylate film is wound around two nip rolls in a heated state. The nip roll on the outlet side conveys the cellulose acylate film at a faster conveying speed than the nip roll on the inlet side, and thereby the cellulose acylate film is stretched in the longitudinal direction.

  The longitudinally stretched cellulose acylate film is sent to the transverse stretching step and is transversely stretched in the width direction. In the transverse stretching step, for example, a tenter can be suitably used. The tenter grips both ends in the width direction of the cellulose acylate film with clips and stretches in the transverse direction (width direction). By this transverse stretching, the retardation Rth can be further increased.

  By performing the longitudinal and lateral stretching processes described above, a stretched cellulose acylate film in which retardation Re and Rth are expressed can be obtained. In the stretched cellulose acylate film, Re is 0 nm to 500 nm, more preferably 10 nm to 400 nm, more preferably 15 nm to 300 nm, Rth is 30 nm to 500 nm, more preferably 50 nm to 400 nm, and further preferably 70 nm or more. 350 nm or less. Of these, those satisfying Re ≦ Rth are more preferable, and those satisfying Re × 2 ≦ Rth are more preferable. In order to realize such a high Rth and low Re, it is preferable to stretch the film that has been longitudinally stretched as described above in the transverse (width) direction. In other words, the difference in orientation between the vertical direction and the horizontal direction becomes the difference in retardation (Re) in the plane, but by stretching in the horizontal direction, which is the orthogonal direction in addition to the vertical direction, the difference in vertical and horizontal orientation is reduced. The surface orientation (Re) can be reduced by reducing the size. On the other hand, since the area magnification increases by stretching in addition to the length, the orientation in the thickness direction increases as the thickness decreases, and Rth can be increased.

  Furthermore, it is preferable that the variation of Re and Rth depending on the location in the width direction and the longitudinal direction is 5% or less, more preferably 4% or less, and still more preferably 3% or less. Further, the orientation angle is preferably 90 ° ± 5 ° or less or 0 ° ± 5 ° or less, more preferably 90 ° ± 3 ° or less, or 0 ° ± 3 ° or less, and further preferably 90 ° ± 1 ° or less or It is preferable to be 0 ° ± 1 ° or less. These can reduce the bowing by performing the stretching treatment as in the present invention, and the straight line drawn along the width direction on the surface of the cellulose acylate film before entering the tenter becomes a recess after the stretching is completed. The bowing distortion obtained by dividing the displacement of the deformed center portion by the width is preferably 10% or less, preferably 5% or less, more preferably 3% or less.

  Hereinafter, a cellulose acylate synthesis method suitable for the present invention, a cellulose acylate film production method, and the like will be described in detail according to procedures.

(1) Plasticizer It is preferable to add a polyhydric alcohol plasticizer to the raw material polymer for producing the cellulose acylate film in the invention. Such a plasticizer not only lowers the elastic modulus, but also has an effect of reducing the difference in crystal amount between the front and back sides. The content of the polyhydric alcohol plasticizer is preferably 2% by mass to 20% by mass with respect to cellulose acylate. The content of the polyhydric alcohol plasticizer is preferably 2% by mass to 20% by mass, more preferably 3% by mass to 18% by mass, and still more preferably 4% by mass to 15% by mass. When the content of the polyhydric alcohol plasticizer is less than 2% by mass, the above effect is not sufficiently achieved. On the other hand, when the content is more than 20% by mass, the plasticizer is deposited on the film surface (called crying out). ) Occurs.

  The polyhydric alcohol plasticizer that can be specifically used in the present invention has good compatibility with cellulose fatty acid esters, and glycerin ester compounds such as glycerin esters and diglycerin esters in which the thermoplastic effect is remarkable, Examples thereof include polyalkylene glycols such as polyethylene glycol and polypropylene glycol, and compounds in which an acyl group is bonded to a hydroxyl group of polyalkylene glycol.

  Specific glycerin esters include glycerin diacetate stearate, glycerin diacetate palmitate, glycerin diacetate myristate, glycerin diacetate laurate, glycerin diacetate caprate, glycerin diacetate nonanate, glycerin diacetate octanoate, Glycerin diacetate heptanoate, glycerol diacetate hexanoate, glycerol diacetate pentanoate, glycerol diacetate oleate, glycerol acetate dicaprate, glycerol acetate dinonanoate, glycerol acetate dioctanoate, glycerol acetate diheptanoate , Glycerol acetate dicaproate, glycerol acetate divalerate, glycerol acetate dibu Glycerol dipropionate caprate, glycerol dipropionate laurate, glycerol dipropionate myristate, glycerol dipropionate palmitate, glycerol dipropionate stearate, glycerol dipropionate oleate, glycerol tributyrate, glycerol tri Examples include but are not limited to pentanoate, glycerin monopalmitate, glycerin monostearate, glycerin distearate, glycerin propionate laurate, glycerin oleate propionate, and these are used alone or in combination. be able to.

  Among these, glycerol diacetate caprylate, glycerol diacetate pelargonate, glycerol diacetate caprate, glycerol diacetate laurate, glycerol diacetate myristate, glycerol diacetate palmitate, glycerol diacetate stearate, glycerol diacetate oleate preferable.

  Specific examples of diglycerin esters include diglycerin tetraacetate, diglycerin tetrapropionate, diglycerin tetrabutyrate, diglycerin tetravalerate, diglycerin tetrahexanoate, diglycerin tetraheptanoate, diglyceride. Glycerin tetracaprylate, diglycerol tetrapelargonate, diglycerol tetracaprate, diglycerol tetralaurate, diglycerol tetramyristate, diglycerol tetrapalmitate, diglycerol triacetate propionate, diglycerol triacetate butyrate, diglycerol Triacetate valerate, diglycerin triacetate hexanoate, diglycerin triacetate heptanoate, diglycerin triacetate caprylate, Glycerin triacetate pelargonate, diglycerol triacetate caprate, diglycerol triacetate laurate, diglycerol triacetate myristate, diglycerol triacetate palmitate, diglycerol triacetate stearate, diglycerol triacetate oleate, diglycerol diacetate dipropionate, diglycerol Diacetate dibutyrate, diglycerol diacetate divalerate, diglycerol diacetate dihexanoate, diglycerol diacetate diheptanoate, diglycerol diacetate dicaprylate, diglycerol diacetate dipelargonate, diglycerol di Acetate dicaprate, diglycerin diacetate dilaurate, diglycerin diacetate dimisti Diglycerin diacetate dipalmitate, diglycerin diacetate distearate, diglycerin diacetate dioleate, diglyceryl acetate tripropionate, diglyceryl acetate tributyrate, diglyceryl acetate trivalerate, diglyceryl acetate tri Hexanoate, diglycerol acetate triheptanoate, diglycerol acetate tricaprylate, diglycerol acetate tripelargonate, diglycerol acetate tricaprate, diglycerol acetate trilaurate, diglycerol acetate trimyristate, diglycerol acetate tri Palmitate, Diglycerol acetate tristearate, Diglycerol acetate trioleate, Diglycerol laurate, Jig Examples include, but are not limited to, mixed acid esters of diglycerin such as glycerin stearate, diglycerin caprylate, diglycerin myristate, and diglycerin oleate, and these can be used alone or in combination.

  Among these, diglycerin tetraacetate, diglycerin tetrapropionate, diglycerin tetrabutyrate, diglycerin tetracaprylate, and diglycerin tetralaurate are preferable.

  Specific examples of the polyalkylene glycol include polyethylene glycol and polypropylene glycol having a weight average molecular weight of 200 to 1,000, but are not limited thereto, and these can be used alone or in combination.

  Specific examples of the compound in which an acyl group is bonded to the hydroxyl group of polyalkylene glycol include polyoxyethylene acetate, polyoxyethylene propionate, polyoxyethylene butyrate, polyoxyethylene valerate, polyoxyethylene caproate, Polyoxyethylene heptanoate, polyoxyethylene octanoate, polyoxyethylene nonanate, polyoxyethylene caprate, polyoxyethylene laurate, polyoxyethylene myristate, polyoxyethylene palmitate, polyoxyethylene stearate , Polyoxyethylene oleate, polyoxyethylene linoleate, polyoxypropylene acetate, polyoxypropylene propionate, polyoxypropylene butyrate, polyoxypropylene Valerate, polyoxypropylene caproate, polyoxypropylene heptanoate, polyoxypropylene octanoate, polyoxypropylene nonanoate, polyoxypropylene caprate, polyoxypropylene laurate, polyoxypropylene myristate, polyoxy Examples thereof include propylene palmitate, polyoxypropylene stearate, polyoxypropylene oleate, and polyoxypropylene linoleate, but are not limited thereto, and these can be used alone or in combination.

  Furthermore, in order to fully express the above-mentioned effects of these polyhydric alcohols, it is preferable to melt and form a cellulose acylate film under the following conditions. That is, pellets obtained by mixing cellulose acylate and polyhydric alcohol are melted with an extruder and extruded from a T die to form a film, but it is preferable that the extruder outlet temperature (T2) is higher than the extruder inlet temperature (T1). More preferably, the die temperature (T3) is higher than the extruder outlet temperature (T2). That is, it is preferable to raise the temperature as the melting of the pellet proceeds. When the temperature is rapidly increased from the inlet, the polyhydric alcohol is first melted and liquefied. In this, the cellulose acylate becomes floating, and a sufficient shearing force cannot be received from the screw, so that an unmelted material is generated. Those which are not sufficiently mixed cannot exhibit the effect of the plasticizer as described above, and the effect of suppressing the difference between the front and back of the melt film after melt extrusion cannot be obtained. Further, such an insoluble material becomes a fish-eye foreign material after film formation. Such foreign matter does not become a bright spot even when observed with a polarizing plate, but rather can be visually recognized by projecting light from the back of the film and observing it in a screen form. In addition, fisheye causes tailing at the die exit and increases the die line.

  T1 is preferably 150 ° C to 200 ° C, more preferably 160 ° C to 195 ° C, and further preferably 165 ° C to 190 ° C. T2 is preferably in the range of 190 ° C to 240 ° C, more preferably 200 ° C to 230 ° C, and still more preferably 200 ° C to 225 ° C. Thus, it is important that the inlet and outlet temperatures T1 and T2 of the extruder are 240 ° C. or lower. When this temperature is exceeded, the elastic modulus of the film formed tends to be high. This is probably because the cellulose acylate is melted at a high temperature and decomposes, which causes cross-linking and increases the elastic modulus. The die temperature T3 is preferably 200 to less than 235 ° C, more preferably 205 to 230 ° C, still more preferably 205 ° C or more and 225 ° C or less.

(2) Stabilizer In the present invention, it is preferable to use either or both of a phosphite compound and a phosphite compound as a stabilizer. Thereby, deterioration over time can be suppressed and the die line can be improved. This is because these compounds function as a leveling agent to eliminate the die line formed by the unevenness of the die. The blending amount of these stabilizers is preferably 0.005% by mass to 0.5% by mass, more preferably 0.01% by mass to 0.4% by mass, and still more preferably 0.02% by mass. % To 0.3% by mass.

(I) Phosphite-based stabilizer The specific phosphite-based anti-coloring agent is not particularly limited, but phosphite-based anti-coloring agents represented by Chemical Formulas 1 to 3 are preferable.

  (Where R1, R2, R3, R4, R5, R6, R′1, R′2, R′3... R′n, R′n + 1 are hydrogen or alkyl having 4 to 23 carbon atoms, aryl, A group selected from the group consisting of alkoxyalkyl, aryloxyalkyl, alkoxyaryl, arylalkyl, alkylaryl, polyaryloxyalkyl, polyalkoxyalkyl and polyalkoxyaryl groups, provided that they are represented by the general formulas (2) (3) (4) In all the same formulas, all are not hydrogen, and all the functional groups RX in each formula are not hydrogen, either is the above-mentioned functional group (such as an alkyl group). ing.

X in the phosphite colorant represented by the general formula (3) is an aliphatic chain, an aliphatic chain having an aromatic nucleus in the side chain, an aliphatic chain having an aromatic nucleus in the chain, and 2 in the above chain. Indicates a group selected from the group consisting of chains containing oxygen atoms that are not consecutive. K and q are integers of 1 or more, and p is an integer of 3 or more. )
The numbers of k and q in these phosphite colorants are preferably 1 to 10. When the number of k and q is 1 or more, volatility during heating is reduced, and when it is 10 or less, compatibility with cellulose acetate propionate is improved, which is preferable. The value of p is preferably 3-10. By making it 3 or more, the volatility at the time of a heating becomes small, and since compatibility with a cellulose acetate propionate improves by making it 10 or less, it is preferable.

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

  Moreover, as a specific example of the phosphite type | system | group coloring inhibitor represented by following General formula (3), what is represented by following formula (9) (10) (11) is preferable.

(Ii) Phosphite ester stabilizer The phosphite stabilizer is, for example, cyclic neopentanetetraylbis (octadecyl) phosphite, cyclic neopentanetetraylbis (2,4-di-t-butyl). Phenyl) phosphite, cyclic neopentanetetraylbis (2,6-di-t-butyl-4-methylphenyl) phosphite, 2,2-methylenebis (4,6-di-t-butylphenyl) octylphos Phyto, tris (2,4-di-t-butylphenyl) phosphite, and the like.

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

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

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

(3) Cellulose acylate << cellulose acylate resin >>
(Composition / Substitution degree)
The cellulose acylate used in the present invention is preferably a cellulose acylate that satisfies all the requirements represented by the following formulas (1) to (3).

2.0 ≦ A + B ≦ 3.0 Formula (1)
0 ≦ A ≦ 2.0 Formula (2)
1.0 ≦ B ≦ 2.9 Formula (3)
(In the above formulas (1) to (3), A represents the degree of substitution of the acetate group, and B represents the sum of the degree of substitution of the propionate group, butyrate group, pentanoyl group and hexanoyl group.)
Preferably,
2.0 ≦ A + B ≦ 3.0 Formula (4)
0 ≦ A ≦ 1.8 Formula (5)
1.2 ≦ B ≦ 2.9 Formula (6)
More preferably 2.4 ≦ A + B ≦ 3.0 Formula (7)
0.05 ≦ A ≦ 1.7 Formula (8)
1.3 ≦ B ≦ 2.9 Formula (9)
More preferably,
2.5 ≦ A + B ≦ 2.95 Formula (10)
0.1 ≦ A ≦ 1.55 Formula (11)
1.4 ≦ B ≦ 2.85 Formula (12)
As described above, the cellulose acylate is characterized by introducing a propionate group, a butyrate group, a pentanoyl group and a hexanoyl group into cellulose. By setting it as such a range, a melting temperature can be lowered | hung and the thermal decomposition accompanying melt film forming can be suppressed, and it is preferable. On the other hand, if the temperature is out of this range, the melting temperature and the thermal decomposition temperature approach each other, and it is difficult to suppress the thermal decomposition, which is not preferable.

These cellulose acylates may be used alone or in combination of two or more. Moreover, what mixed suitably polymer components other than a cellulose acylate may be used.
Next, the manufacturing method of the cellulose acylate used for this invention is demonstrated in detail. The raw material cotton and the synthesis method of the cellulose acylate of the present invention are also described in detail on pages 7 to 12 of the Japan Society for Invention and Technology (public technical number 2001-1745, published on March 15, 2001, Japan Society for Invention). Are listed.

(Raw material and pretreatment)
As the cellulose raw material, those derived from hardwood pulp, softwood pulp and cotton linter are preferably used. As the cellulose raw material, it is preferable to use a high-purity material having an α-cellulose content of 92% by mass or more and 99.9% by mass or less. When the cellulose raw material is in the form of a film or a lump, it is preferable that the cellulose is crushed in advance, and the pulverization is preferably progressed until the cellulose is in a fluff form.

(activation)
Prior to acylation, the cellulose raw material is preferably subjected to a treatment (activation) in contact with an activator. As the activator, carboxylic acid or water can be used. The addition method can be selected from methods such as spraying, dropping, and dipping.

  Preferred carboxylic acids as activators are carboxylic acids having 2 to 7 carbon atoms (for example, acetic acid, propionic acid, butyric acid, 2-methylpropionic acid, valeric acid, 3-methylbutyric acid, 2-methylbutyric acid, 2,2 -Dimethylpropionic acid (pivalic acid), hexanoic acid, 2-methylvaleric acid, 3-methylvaleric acid, 4-methylvaleric acid, 2,2-dimethylbutyric acid, 2,3-dimethylbutyric acid, 3,3-dimethylbutyric acid , Cyclopentanecarboxylic acid, heptanoic acid, cyclohexanecarboxylic acid, benzoic acid, etc.), more preferably acetic acid, propionic acid, or butyric acid, and particularly preferably acetic acid.

  At the time of activation, an acylation catalyst such as sulfuric acid may be added in an amount of 0.1% by mass to 10% by mass with respect to the cellulose, if necessary. Two or more kinds of activators may be used in combination, or an acid anhydride of a carboxylic acid having 2 to 7 carbon atoms may be added.

  At the time of activation, it is preferable that an acylation catalyst such as sulfuric acid is further limited to about 0.1% by mass to 10% by mass with respect to cellulose as necessary. Two or more kinds of activators may be used in combination, or an acid anhydride of a carboxylic acid having 2 to 7 carbon atoms may be added.

  The addition amount of the activator is preferably 5% by mass or more, more preferably 10% by mass or more, and particularly preferably 30% by mass or more based on cellulose. The upper limit of the addition amount of the activator is not particularly limited as long as productivity is not lowered, but it is preferably 100 times or less, more preferably 20 times or less, and 10 times or less by mass with respect to cellulose. It is particularly preferred that

  The activation time is preferably 20 minutes or more, and the upper limit is not particularly limited as long as it does not affect the productivity, but is preferably 72 hours or less, more preferably 24 hours or less, particularly preferably. 12 hours or less. The activation temperature is preferably 0 ° C. or higher and 90 ° C. or lower, more preferably 15 ° C. or higher and 80 ° C. or lower, and particularly preferably 20 ° C. or higher and 60 ° C. or lower.

(Acylation)
As a method for obtaining cellulose acylate used in the present invention, a method of reacting two carboxylic acid anhydrides as an acylating agent by mixing or sequentially adding them, a mixed acid anhydride of two carboxylic acids (for example, acetic acid. A method using a propionic acid mixed acid anhydride), a mixed acid anhydride (for example, acetic acid / propionic acid) in a reaction system using an acid anhydride of a carboxylic acid and another carboxylic acid (for example, acetic acid and propionic acid anhydride) as a raw material A method of synthesizing a mixed acid anhydride) and reacting with cellulose, a method of once synthesizing a cellulose acylate having a substitution degree of less than 3, and further acylating the remaining hydroxyl group with an acid anhydride or an acid halide, etc. Can be used. The synthesis of cellulose acylate having a high degree of substitution at the 6-position is described in publications such as JP-A Nos. 11-5851, 2002-212338, and 2002-338601.

(Acid anhydride)
The acid anhydride of the carboxylic acid preferably has 2 to 7 carbon atoms as the carboxylic acid, and examples thereof include acetic anhydride, propionic anhydride, butyric anhydride, hexanoic anhydride, benzoic anhydride, and the like. be able to. More preferred are acetic anhydride, propionic anhydride, butyric anhydride, hexanoic anhydride, and particularly preferred are acetic anhydride, propionic anhydride, butyric anhydride.

  The acid anhydride is usually added in excess equivalent to the cellulose. That is, it is preferable to add 1.1 equivalent-50 equivalent with respect to the hydroxyl group of a cellulose, It is more preferable to add 1.2 equivalent-30 equivalent, It is especially preferable to add 1.5 equivalent-10 equivalent.

(catalyst)
As the acylation catalyst used for producing the cellulose acylate used in the present invention, it is preferable to use Bronsted acid or Lewis acid. The definitions of Bronsted acid and Lewis acid are described in, for example, “Physical and Chemical Dictionary”, 5th edition (2000). As the catalyst, sulfuric acid or perchloric acid is more preferable, and sulfuric acid is particularly preferable. A preferable addition amount of the catalyst is 0.1% by mass to 30% by mass with respect to cellulose, more preferably 1% by mass to 15% by mass, and particularly preferably 3% by mass to 12% by mass.

(solvent)
In carrying out acylation, a solvent may be added for the purpose of adjusting viscosity, reaction rate, stirring property, acyl substitution ratio, and the like. The solvent is preferably a carboxylic acid, and more preferably a carboxylic acid having 2 to 7 carbon atoms (for example, acetic acid, propionic acid, butyric acid, hexanoic acid, benzoic acid). Particularly preferred are acetic acid, propionic acid, butyric acid and the like. These solvents may be used as a mixture.

(Conditions for acylation)
When acylation is performed, an acid anhydride and a catalyst, and further, if necessary, a solvent may be mixed and then mixed with cellulose, or these may be separately mixed with cellulose. It is preferable to prepare a mixture of an acid anhydride and a catalyst or a mixture of an acid anhydride, a catalyst and a solvent as an acylating agent and then react with cellulose. In order to suppress an increase in temperature in the reaction vessel due to reaction heat during acylation, the acylating agent is preferably cooled in advance.

  Further, the acylating agent may be added to the cellulose at once or dividedly. In addition, cellulose may be added to the acylating agent all at once or in divided portions. It is preferable that the maximum temperature reached during acylation is 50 ° C. or lower. If the reaction temperature is lower than this temperature, depolymerization proceeds and it is preferable because there is no inconvenience such as difficulty in obtaining a cellulose acylate having a polymerization degree suitable for the use of the present invention. The maximum temperature reached during acylation is preferably 45 ° C. or lower, more preferably 40 ° C. or lower, and particularly preferably 35 ° C. or lower. The minimum reaction temperature is preferably −50 ° C. or higher, more preferably −30 ° C. or higher, and particularly preferably −20 ° C. or higher. The acylation time is preferably 0.5 hours or more and 24 hours or less, more preferably 1 hour or more and 12 hours or less, and particularly preferably 1.5 hours or more and 10 hours or less.

(Reaction terminator)
In the method for producing cellulose acylate used in the present invention, it is preferable to add a reaction terminator after the acylation reaction. Any reaction terminator may be used as long as it decomposes the acid anhydride, and preferred examples include water, alcohols (eg, ethanol, methanol, propanol, isopropyl alcohol, etc.) or compositions containing these. be able to. It is preferable to add a mixture of carboxylic acid such as acetic acid, propionic acid, butyric acid and water, and acetic acid is particularly preferable as the carboxylic acid. The composition ratio of carboxylic acid and water can be used at any ratio, but the water content is 5% by mass to 80% by mass, further 10% by mass to 60% by mass, and particularly 15% by mass to 50% by mass. It is preferable that it is the range of these.

(Neutralizer)
After the acylation stop step or the acylation stop step, hydrolysis of excess carboxylic anhydride remaining in the system, neutralization of some or all of the carboxylic acid and esterification catalyst, residual sulfate radical amount In order to adjust the amount of residual metal and the like, a neutralizing agent or a solution thereof may be added.

  Preferred examples of the neutralizing agent include ammonium, organic quaternary ammonium, alkali metal, group 2 metal, group 3-12 metal, or group 13-15 element carbonate, bicarbonate, organic acid salt. (For example, acetate, propionate, butyrate, benzoate, phthalate, hydrogen phthalate, citrate, tartrate, etc.), hydroxide or oxide can be used. More preferably, the neutralizing agent is a carbonate, bicarbonate, organic acid salt, hydroxide or oxide of an alkali metal or a group 2 metal, and particularly preferably sodium, potassium, magnesium or calcium. , Carbonates, bicarbonates, acetates or hydroxides. Preferred examples of the neutralizing agent solvent include water, organic acids (for example, acetic acid, propionic acid, butyric acid, and the like) and mixed solvents thereof.

(Partial hydrolysis)
The cellulose acylate thus obtained has a total degree of substitution close to 3. However, for the purpose of obtaining a desired degree of substitution, a small amount of catalyst (generally, acylation of remaining sulfuric acid or the like) is performed. (Catalyst) and water in the presence of water at 20 ° C. to 90 ° C. for several minutes to several days to partially hydrolyze the ester bond and reduce the acyl substitution degree of cellulose acylate to a desired level ( So-called aging) is generally performed. When the desired cellulose acylate is obtained, it is preferable to completely neutralize the catalyst remaining in the system using the neutralizing agent as described above or a solution thereof to stop partial hydrolysis. . By adding a neutralizing agent (for example, magnesium carbonate, magnesium acetate, etc.) that generates a salt that is poorly soluble in the reaction solution, a catalyst (for example, sulfate ester) bound to the solution or to cellulose is effectively removed. It is also preferable to remove.

(Filtration)
The reaction mixture is preferably filtered for the purpose of removing or reducing unreacted substances, hardly soluble salts, and other foreign matters in the cellulose acylate. Filtration may be performed in any step from completion of acylation to reprecipitation. For the purpose of controlling filtration pressure and handleability, it is also preferable to dilute with an appropriate solvent prior to filtration. A cellulose acylate solution is obtained through filtration.

(Reprecipitation)
The cellulose acylate solution thus obtained is mixed in a poor solvent such as water or an aqueous solution of carboxylic acid (for example, acetic acid, propionic acid, etc.), or the poor solvent is mixed in the cellulose acylate solution. Thus, the cellulose acylate can be re-precipitated, and the desired cellulose acylate can be obtained by washing and stabilizing treatment. The reprecipitation may be carried out continuously or batchwise by a fixed amount.

(Washing)
The produced cellulose acylate is preferably washed. Any washing solvent may be used as long as it has low solubility of cellulose acylate and can remove impurities, but water or warm water is usually used. The progress of washing may be traced by any means, but preferred examples include methods such as hydrogen ion concentration, ion chromatography, electrical conductivity, ICP (radio frequency inductively coupled plasma) emission spectroscopic analysis, elemental analysis, and atomic absorption analysis. Can be mentioned.

(Stabilization)
Cellulose acylate after washing by hot water treatment is weakly alkaline (for example, carbonates such as sodium, potassium, calcium, magnesium, aluminum, carbonates, etc.) in order to further improve the stability and reduce the carboxylic acid odor. Treatment with an aqueous solution of hydrogen salt, hydroxide, oxide, etc.) is also preferable.

(Dry)
In the present invention, in order to adjust the water content of the cellulose acylate to a preferable amount, it is preferable to dry the cellulose acylate. The drying temperature is preferably 0 ° C to 200 ° C, more preferably 40 ° C to 180 ° C, and particularly preferably 50 ° C to 160 ° C. The cellulose acylate of the present invention has a water content of preferably 2% by mass or less, more preferably 1% by mass or less, and particularly preferably 0.7% by mass or less.

(Form)
The cellulose acylate of the present invention can take various shapes such as particles, powders, fibers and lumps, but it is preferable that the raw materials for film production are particles or powders. Cellulose acylate may be pulverized or sieved for uniform particle size and improved handling. When the cellulose acylate is in the form of particles, 90% by mass or more of the particles used preferably have a particle diameter of 0.5 mm to 5 mm. Moreover, it is preferable that 50 mass% or more of the particle | grains to be used have a particle diameter of 1 mm-4 mm. The cellulose acylate particles preferably have a shape as close to a sphere as possible. The cellulose acylate particles used in the present invention preferably have an apparent density of 0.5 g / cm ³ to 1.3 g / cm ³ , more preferably 0.7 g / cm ³ to 1.2 g / cm ³ , particularly It is preferably 0.8 g / cm ³ to 1.15 g / cm ³ . The method for measuring the apparent density is defined in JIS K-7365. The cellulose acylate particles of the present invention preferably have an angle of repose of 10 ° to 70 °, more preferably 15 ° to 60 °, and particularly preferably 20 ° to 50 °.

(Degree of polymerization)
The degree of polymerization of cellulose acylate preferably used in the present invention is an average degree of polymerization of 100 to 700, preferably 120 to 600, and more preferably 130 to 450. The average degree of polymerization is determined by Uda et al.'S intrinsic viscosity method (Kazuo Uda, Hideo Saito, Journal of Textile Society, Vol. 18, No. 1, pages 105-120, 1962), molecular weight distribution measurement by gel permeation chromatography (GPC), etc. It can be measured by this method. Further details are described in JP-A-9-95538.

[Synthesis example of cellulose acylate]
Although the synthesis example of the cellulose acylate used for this invention is demonstrated below, this invention is not limited to these.

[Synthesis Example 1] Synthesis of cellulose acetate propionate 0.1 parts by mass of acetic acid and 2.7 parts by mass of propionic acid were sprayed on 10 parts by mass of cellulose (hardwood pulp) and stored at room temperature for 1 hour. Separately, a mixture of 1.2 parts by mass of acetic anhydride, 61 parts by mass of propionic anhydride, and 0.7 parts by mass of sulfuric acid was prepared, and after cooling to −10 ° C., the mixture was mixed in the reaction vessel with the pretreated cellulose. did.

  After 30 minutes, the external temperature was raised to 30 ° C. and reacted for 4 hours. 46 parts by mass of 25% aqueous acetic acid was added to the reaction vessel, the internal temperature was raised to 60 ° C., and the mixture was stirred for 2 hours. 6.2 parts by mass of a solution prepared by mixing equal parts of magnesium acetate tetrahydrate, acetic acid and water was added and stirred for 30 minutes (neutralization step). The reaction solution was subjected to pressure filtration with a sintered metal filter (retained particle diameter of 40 μm, 10 μm in two stages) to remove foreign matters. The reaction solution after filtration was mixed with 75% aqueous acetic acid to precipitate cellulose acetate propionate, and then washed with warm water at 70 ° C. until the pH of the washing solution became 6-7. Further, the solution was stirred in a 0.001% calcium hydroxide aqueous solution for 0.5 hours and then filtered. The obtained cellulose acetate propionate was dried at 70 ° C. Cellulose acetate propionate obtained from 1H-NMR measurement has a degree of acetylation of 0.15, a degree of propionylation of 2.62, a total degree of acyl substitution of 2.77, and a number average molecular weight of 54500 (number average degree of polymerization DPn = 173). , Mass average molecular weight 132000 (mass average polymerization degree DPw = 419), residual sulfuric acid content 45 ppm, magnesium content 8 ppm, calcium content 46 ppm, sodium content 1 ppm, potassium content 1 ppm, iron content 2 ppm. As a result of observing the film cast from the dichloromethane solution of this sample with a polarizing microscope, almost no foreign matter was observed when the polarizers were made orthogonal or parallel.

[Synthesis Example 2] Synthesis of cellulose acetate propionate 80 parts by weight of cellulose (pulp) and 33 parts by weight of acetic acid were placed in a reaction vessel equipped with a stirrer and a cooling device, and treated at 60 ° C for 4 hours to activate cellulose. Turned into. 33 parts by mass of acetic anhydride, 518 parts by mass of propionic acid, 536 parts by mass of propionic anhydride and 4 parts by mass of sulfuric acid were mixed, cooled to −20 ° C., and then added to the reaction vessel.

  Esterification was performed so that the maximum temperature of the reaction was 35 ° C., and the time when the viscosity of the reaction solution reached 840 cP was taken as the end point of the reaction. The temperature of the reaction mixture at the end point was adjusted to 15 ° C. The reaction terminator which cooled the mixture of 133 mass parts of water and 133 mass parts of acetic acid to -5 degreeC was added so that the temperature of a reaction mixture might not exceed 23 degreeC.

  The temperature of the reaction mixture was set to 60 ° C., and the mixture was stirred for 2 hours for partial hydrolysis, and the partial hydrolysis was stopped with an acetic acid / water mixed solution containing 2 equivalents of magnesium acetate with respect to sulfuric acid. The reaction solution after hydrolysis was sequentially filtered through a filter paper having a reserved particle diameter of 40 μm and a sintered metal filter having a reserved particle diameter of 10 μm. The polymer compound obtained by mixing with an acetic acid aqueous solution was reprecipitated, and washing with warm water at 70 to 80 ° C. was repeated. After removing the liquid, it was immersed in a 0.001% by mass calcium hydroxide aqueous solution, stirred for 30 minutes, and then removed again. Drying was performed at 70 ° C. to obtain cellulose acetate propionate.

  The obtained cellulose acetate propionate has an acetyl substitution degree of 0.42, a propionyl substitution degree of 2.40, a total acyl substitution degree of 2.82, a number average molecular weight of 50200 (number average polymerization degree DPn = 159), and a mass average molecular weight of 125900. (Mass-average polymerization degree DPw = 398), residual sulfuric acid content 85 ppm, magnesium content 2 ppm, calcium content 39 ppm, sodium content 1 ppm, potassium content was below the detection limit and iron content 3 ppm. As a result of observing the film cast from the dichloromethane solution of this sample with a polarizing microscope, almost no insoluble matter was observed.

[Synthesis Example 3] Synthesis of cellulose acetate butyrate 200 parts by weight of cellulose (linter) and 100 parts by weight of acetic acid were placed in a reaction vessel equipped with a stirrer and a cooling device, and the cellulose was activated by treating at 60 ° C for 4 hours. Turned into. 161 parts by mass of acetic acid, 449 parts by mass of acetic anhydride, 742 parts by mass of butyric acid, 1349 parts by mass of butyric anhydride, and 14 parts by mass of sulfuric acid were mixed and cooled to −20 ° C., and then added to the reaction vessel.

  Esterification was performed so that the maximum temperature of the reaction was 30 ° C., and the time when the viscosity of the reaction solution reached 1050 cP was taken as the end point of the reaction. The temperature of the reaction mixture at the end point was adjusted to 10 ° C. A reaction stopper obtained by cooling a mixture of 297 parts by mass of water and 558 parts by mass of acetic acid to −5 ° C. was added so that the temperature of the reaction mixture did not exceed 23 ° C.

  The temperature of the reaction mixture was set to 60 ° C., and the mixture was stirred for 2 hours and 30 minutes to perform partial hydrolysis. The partial hydrolysis was stopped with an acetic acid / water mixed solution containing 2 equivalents of magnesium acetate with respect to sulfuric acid. The reaction solution after hydrolysis was sequentially filtered through a filter paper having a reserved particle diameter of 40 μm and a sintered metal filter having a reserved particle diameter of 10 μm. The polymer compound obtained by mixing with an acetic acid aqueous solution was reprecipitated, and washing with warm water at 70 to 80 ° C. was repeated. After removing the liquid, it was immersed in a 0.002% by mass calcium hydroxide aqueous solution, stirred for 30 minutes, and then removed again. Drying was performed at 70 ° C. to obtain cellulose acetate butyrate.

  The resulting cellulose acetate butyrate has an acetyl substitution degree of 1.51, a butyryl substitution degree of 1.19, a total acyl substitution degree of 2.70, a number average molecular weight of 55600 (number average polymerization degree DPn = 181), and a weight average molecular weight of 139000 ( (Mass average polymerization degree DPw = 451), residual sulfuric acid content 122 ppm, magnesium content 3 ppm, calcium content 53 ppm, sodium content 1 ppm, potassium content 2 ppm, iron content 2 ppm. As a result of observing the film cast from the dichloromethane solution of this sample with a polarizing microscope, almost no insoluble matter was observed.

(4) Other additives (i) Matting agent It is preferable to add fine particles as a matting agent. The fine particles used in the present invention include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, silica Mention may be made of magnesium and calcium phosphates. Fine particles containing silicon are preferable because they can reduce turbidity, and silicon dioxide is particularly preferable. The fine particles of silicon dioxide preferably have a primary average particle diameter of 20 nm or less and an apparent specific gravity of 70 g / liter or more. Those having an average primary particle size as small as 5 to 16 nm are more preferred because they can reduce the haze of the film. The apparent specific gravity is preferably 90 g / liter to 200 g / liter, and more preferably 100 g / liter to 200 g / liter. A larger apparent specific gravity is preferable because a high-concentration dispersion can be produced, and haze and aggregates are improved.

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

  As the fine particles of silicon dioxide, for example, commercially available products such as Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (above Nippon Aerosil Co., Ltd.) can be used. Zirconium oxide fine particles are commercially available, for example, under the trade names Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.) and can be used. Among them, Aerosil 200V and Aerosil R972V have a primary average particle diameter of 20 nm or less and an apparent specific gravity of 70 g / liter or more, and are fine particles of silicon dioxide. It is particularly preferable because it has a great effect of reducing the effect.

(Ii) Other additives Various additives other than the above, for example, ultraviolet ray inhibitors (for example, hydroxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, cyanoacrylate compounds, etc.), infrared absorbers, optical modifiers , Surfactants and odor trapping agents (such as amines) can be added. These details are disclosed in the Invention Association Public Technique No. 2001-1745 (issued March 15, 2001, Invention Association), p. Materials described in detail in 17-22 are preferably used.

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

  Examples of the optical adjusting agent include a retardation adjusting agent. For example, as described in JP-A No. 2001-166144, JP-A No. 2003-344655, JP-A No. 2003-248117, and JP-A No. 2003-66230. In this case, in-plane retardation (Re) and thickness direction retardation (Rth) can be controlled. A preferable addition amount is 10% by mass or less, more preferably 8% by mass or less, and further preferably 6% by mass or less.

(5) Physical properties of cellulose acylate mixture The cellulose acylate mixture (a mixture of cellulose acylate, plasticizer, stabilizer, and other additives) preferably satisfies the following physical properties.

(I) Heat loss rate The heat loss rate refers to the weight loss rate at 220 ° C. when the sample is heated from room temperature at a rate of temperature increase of 10 ° C./min in a nitrogen gas atmosphere. By preparing the cellulose acylate mixture, the weight loss on heating can be reduced to 5% by weight or less. More preferably, it is 3 weight% or less, More preferably, it is 1 weight% or less. By doing in this way, the malfunction (bubble generation) which generate | occur | produces during film forming can be suppressed.

(Ii) Melt viscosity The cellulose acylate mixture preferably has a melt viscosity at 220 ° C. and 1 sec ⁻¹ of 100 Pa · s to 1000 Pa · s, more preferably 200 Pa · s to 800 Pa · s, and even more preferably 300 Pa · s to 700 Pa · s. By making such a high melt viscosity, it is not stretched (stretched) by the tension at the die exit, and an increase in optical anisotropy (retardation) due to stretch orientation can be prevented. Such adjustment of the viscosity may be achieved by any method, but can be achieved by, for example, the degree of polymerization of cellulose acylate and the amount of additives such as a plasticizer.

(6) Pelletization The cellulose acylate mixture is preferably mixed and pelletized prior to melt film formation. In the pelletization, the cellulose acylate mixture is preferably dried in advance, but this can be substituted by using a vented extruder. In the case of drying, a method of heating at 90 ° C. for 8 hours or more in a heating furnace can be used as a drying method, but this is not restrictive. Pelletization can be performed by melting the cellulose acylate mixture at 150 ° C. or more and 250 ° C. or less using a biaxial kneading extruder and then extruding it into noodles and solidifying and cutting in water. Further, pelletization may be performed by an underwater cutting method or the like that is cut while being directly extruded from a die after being melted by an extruder.

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

The size of the pellet is preferably 1 mm ² or more and 300 mm ² or less, and the length is preferably 1 mm or more and 30 mm or less, more preferably 2 mm ² or more and 100 mm ² or less, and the length is 1.5 mm or more and 10 mm or less. . Moreover, when pelletizing, the said additive can also be injected | thrown-in from the raw material input port and vent port in the middle of an extruder.

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

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

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

(Ii) Melt Extrusion The cellulose acylate described above is supplied into the cylinder via a supply port of an extruder (separate from the pelletizing extruder). The resin is preferably dried in order to reduce the amount of water by the above-mentioned method. However, in order to prevent the molten resin from being oxidized by residual oxygen, the inside of the extruder is in an inert (nitrogen or the like) air flow or with a vent. More preferably, it is carried out while evacuating using an extruder. The screw compression ratio of the extruder is set to 2.5 to 4.5, and L / D is set to 20 to 70. L / D is the ratio of the cylinder length to the cylinder inner diameter. The extrusion temperature is set to 190 ° C to 240 ° C. When the temperature in the extruder exceeds 240 ° C., a cooler may be provided between the extruder and the die.

  On the other hand, if L / D is less than 20 and is too small, melting and kneading are insufficient, and fine crystals are likely to remain in the cellulose acylate film after production. On the other hand, if L / D exceeds 70 and is too large, the residence time of the cellulose acylate resin in the extruder becomes too long, and the resin tends to be deteriorated. In addition, when the residence time is long, the molecular strength is reduced or the molecular weight is lowered, so that the mechanical strength of the cellulose acylate film is lowered. Therefore, L / D is preferably in the range of 20 to 70, and more preferably in the range of 22 to 65, in order to make the cellulose acylate film after production hardly yellow, and the film strength is strong and the stretch breakage is difficult. Especially preferably, it is the range of 24-50.

  The extrusion temperature is preferably in the above temperature range. The cellulose acylate film thus obtained has characteristic values having a haze of 2.0% or less and a yellow index (YI value) of 10 or less.

  Here, haze is an index indicating whether the extrusion temperature is too low, in other words, an index for knowing the amount of crystals remaining in the cellulose acylate film after production. If haze exceeds 2.0%, cellulose after production is obtained. Decrease in strength of the acylate film and breakage during stretching are likely to occur. The yellow index (YI value) is an index for knowing whether the extrusion temperature is too high. If the yellow index (YI value) is 10 or less, there is no problem in terms of yellowness.

  As a type of extruder, a single screw extruder with a relatively low equipment cost is generally used, and there are screw types such as full flight, mudock, and dalmage, but cellulose acid with relatively poor thermal stability. The rate is preferably a full flight type. In addition, although the equipment cost is effective, it is possible to use a twin-screw extruder that can extrude while volatilizing unnecessary volatile components by providing a vent port in the middle by changing the screw segment. There are two types of axial extruders, the same direction and the different direction, which can be used. However, it is preferable to use the same-direction rotation type in which a stagnant portion hardly occurs and high self-cleaning performance. The twin-screw extruder is effective, but it is suitable for film formation using cellulose acylate because it has high kneadability and high resin supply performance, and can be extruded at a low temperature. By appropriately arranging the vent opening, it is possible to use the cellulose acylate pellets and powder in an undried state as they are. Also, film smears produced during film formation can be reused without drying.

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

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

(Iv) Gear pump In order to improve the thickness accuracy, it is important to reduce the fluctuation of the discharge amount. A gear pump is provided between the extruder and the die, and a certain amount of cellulose acylate resin is supplied from the gear pump. That is effective. A gear pump is accommodated in a state where a pair of gears consisting of a drive gear and a driven gear are engaged with each other, and is driven from the suction port formed in the housing (gear box) by driving the drive gear and rotating both the gears. The molten resin is sucked into the cavity, and a certain amount of the resin is discharged from a discharge port formed in the housing. Even if there is a slight fluctuation in the resin pressure at the tip portion of the extruder, the fluctuation is absorbed by using the gear pump, the fluctuation in the resin pressure downstream of the film forming apparatus becomes very small, and the thickness fluctuation is improved.

  In order to improve the quantitative supply performance by the gear pump, a method of controlling the pressure before the gear pump to be constant by changing the number of rotations of the screw can also be used. In addition, a high-precision gear pump using three or more gears that eliminates gear fluctuations of the gear pump is also effective.

  Other advantages of using a gear pump are that the pressure at the tip of the screw can be reduced to form a film, reducing energy consumption, preventing the temperature increase of cellulose acylate, improving transport efficiency, shortening the residence time in the extruder, Shortening the L / D of the extruder can be expected. Also, when using a filter to remove foreign matter, if there is no gear pump, the amount of resin supplied from the screw may fluctuate as the filtration pressure increases. It can be resolved.

The preferred residence time of the resin from when the cellulose acylate enters the extruder through the supply port until it exits the die is 2 minutes or more and 60 minutes or less, more preferably 3 minutes or more and 40 minutes or less, and even more preferably 4 minutes. It is 30 minutes or less.

  The deterioration of the flow of the polymer for bearing circulation of the gear pump deteriorates the sealing by the polymer in the drive part and the bearing part, and there is a problem that the fluctuation of the metering and the liquid feeding pressure is increased. A gear pump design (especially clearance) that matches the melt viscosity is required. In some cases, the staying part of the gear pump causes deterioration of the cellulose acylate, and therefore a structure with as little staying as possible is preferable. As for piping and adapters connecting the extruder and gear pump or gear pump and die, etc., it is necessary to have a design with as little stagnation as possible, and in order to stabilize the extrusion pressure of cellulose acylate whose melt viscosity is highly temperature-dependent, It is preferable to make the temperature fluctuation as small as possible. Generally, a band heater with a low equipment cost is often used for heating the pipe, but it is more preferable to use an aluminum cast-in heater with less temperature fluctuation. Furthermore, in order to stabilize the discharge pressure of the extruder as described above, it is preferable to heat and melt the barrel of the extruder with a heater divided into 3 or more and 20 or less.

(V) Die The cellulose acylate is melted by the extruder configured as described above, and the molten resin (cellulose acylate) is continuously fed to the die via a filter and a gear pump as necessary. As long as the die is designed so that the molten resin does not stay in the die, any type of commonly used T-die, fishtail die, and hanger coat die may be used. Also, there is no problem to insert a static mixer for improving the uniformity of the resin temperature immediately before the T die. The clearance at the exit of the T die is generally 1.0 to 5.0 times the film thickness, preferably 1.2 to 3 times, more preferably 1.3 to 2 times. When the lip clearance is less than 1.0 times the film thickness, it is difficult to obtain a good surface film by film formation. Further, when the lip clearance is larger than 5.0 times the film thickness, the film thickness accuracy is lowered, which is not preferable. The die is a very important facility for determining the thickness accuracy of the film, and a die that can control the thickness adjustment severely is preferable. Usually, the thickness can be adjusted at intervals of 40 mm to 50 mm, preferably a type capable of adjusting the film thickness at intervals of 35 mm or less, more preferably at intervals of 25 mm or less. In addition, since cellulose acylate has high temperature dependence and shear rate dependence of melt viscosity, it is important to design the die with as little temperature unevenness as possible and unevenness in flow velocity in the width direction. An automatic thickness adjustment die that measures downstream film thickness, calculates thickness deviation, and feeds back the result to die thickness adjustment is also effective in reducing thickness fluctuations in long-term continuous production.

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

(Vi) Cast The cellulose acylate extruded into a sheet form from the die by the above method is cooled and solidified on a cooling drum to obtain a film. At this time, using an electrostatic application method, an air knife method, an air chamber method, a vacuum nozzle method, a touch roll method, or the like, a method for improving the adhesion between the cooling drum and the melt-extruded sheet-like cellulose acylate is performed. Is preferred. Such an adhesion improving method may be performed on the entire surface of the melt-extruded sheet or a part thereof. In particular, a method called edge pinning, in which only both ends of the sheet are brought into close contact, is often used, but the method is not limited to this.

A method of using a plurality of cooling drums and gradually cooling them is more preferable. In particular, it is relatively common to use three cooling drums, but this is not restrictive. The diameter of the cooling drum is preferably 100 mm or more and 1000 mm or less, and more preferably 150 mm or more and 1000 mm or less. The interval between the plurality of cooling drums is preferably 1 mm or more and 50 mm or less, more preferably 1 mm or more and 30 mm or less.

  The cooling drum is preferably 60 ° C. or higher and 160 ° C. or lower, more preferably 70 ° C. or higher and 150 ° C. or lower, and further preferably 80 ° C. or higher and 140 ° C. or lower. Then, it peels off from a cooling drum, winds up after passing through a take-off roller (nip roll). The winding speed is preferably from 10 m / min to 100 m / min, more preferably from 15 m / min to 80 m / min, still more preferably from 20 m / min to 70 m / min.

  The film forming width is 0.7 m or more and 5 m or less, more preferably 1 m or more and 4 m or less, and further preferably 1.3 m or more and 3 m or less. The thickness of the unstretched film thus obtained is preferably 30 μm or more and 400 μm or less, more preferably 40 μm or more and 300 μm or less, and still more preferably 50 μm or more and 200 μm or less.

  When the so-called touch roll method is used, the touch roll surface may be a plastic such as rubber or Teflon (registered trademark) or a metal roll. Further, it is possible to use a roll called a flexible roll because the roll surface is slightly dented by the pressure when touched by reducing the thickness of the metal roll, and the crimping area is widened. The touch roll temperature is preferably 60 ° C. or higher and 160 ° C. or lower, more preferably 70 ° C. or higher and 150 ° C. or lower, and further preferably 80 ° C. or higher and 140 ° C. or lower.

(Vii) Winding The sheet thus obtained is preferably trimmed at both ends and wound. The trimmed part is recycled as a raw material for the same type of film or as a raw material for a film of a different type after being pulverized or after being subjected to a granulation process or a depolymerization / repolymerization process as necessary. May be used. As the trimming cutter, any type of rotary cutter, shear blade, knife, or the like may be used. Any material such as carbon steel or stainless steel may be used. In general, it is preferable to use a cemented carbide blade or a ceramic blade because the life of the blade is long and the generation of chips is suppressed.

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

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

(Viii) Physical Properties of Unstretched Cellulose Acylate Film The unstretched cellulose acylate film thus obtained is preferably Re = 0 nm to 20 nm, Rth = 0 nm to 80 nm, more preferably Re = 0 nm to 15 nm, Rth = 0 nm ˜70 nm, more preferably Re = 0 nm to 10 nm, Rth = 0 nm to 60 nm. Re and Rth respectively represent in-plane retardation and retardation in the thickness direction. Re is measured with KOBRA 21ADH (manufactured by Oji Scientific Instruments) by making light incident in the normal direction of the film. Rth is the above-mentioned Re and the retardation measured by injecting light from directions inclined by + 40 ° and −40 ° with respect to the film normal direction with the in-plane slow axis as the tilt axis (rotation axis). Calculation is based on the retardation value measured from three directions. The angle θ formed by the film forming direction (longitudinal direction) and the slow axis of Re of the film is preferably closer to 0 °, + 90 °, or −90 °. The total light transmittance is preferably 90% or more, more preferably 91% or more, and still more preferably 98% or more. The preferred haze is 1% or less, more preferably 0.8% or less, and still more preferably 0.6% or less.

The thickness unevenness is preferably 0% or more and 4% or less in both the longitudinal direction and the width direction, more preferably 0% or more and 3% or less, and further preferably 0% or more and 2% or less. Preferably, the modulus in tension is 1.5 kN / mm ² or more 3.5 kN / mm ² or less, more preferably 1.7 kN / mm ² or more 2.8 kN / mm ² or less, more preferably 1.8 kN / mm ² or more 2 .6 kN / mm ² or less. The breaking elongation is preferably 3% to 100%, more preferably 5% to 80%, and still more preferably 8% to 50%.

Tg (Tg of film, ie, Tg of cellulose acylate and additive) is preferably 95 ° C. or higher and 145 ° C. or lower, more preferably 100 ° C. or higher and 140 ° C. or lower, and still more preferably 105 ° C. or higher and 135 ° C. or lower. is there. The thermal dimensional change at 80 ° C for one day is preferably 0% or more and ± 1% or less in both the vertical and horizontal directions, more preferably 0% or more and ± 0.5% or less, and further preferably 0% or more and ± 0.3% or less. It is. The water permeability at 40 ° C. and 90% rh is preferably 300 g / m ² · day to 1000 g / m ² · day, more preferably 400 g / m ² · day to 900 g / m ² · day, more preferably 500 g / m. m ² · day to 800 g / m ² · day. The equilibrium water content at 25 ° C. and 80% rh is preferably 1% by mass to 4% by mass, more preferably 1.2% by mass to 3% by mass, and still more preferably 1.5% by mass to 2.5% by mass. It is as follows.

(8) Stretching The film formed by the above method may be stretched. Thereby, Re and Rth can be controlled. The stretching is preferably performed at Tg (° C.) or more and (Tg + 50) ° C., more preferably (Tg + 3) ° C. or more and (Tg + 30) ° C. or less, and further preferably (Tg + 5) ° C. or more and (Tg + 20) ° C. or less. A preferred draw ratio is 1% or more and 300% or less on at least one side, more preferably 2% or more and 250% or less, and further preferably 3% or more and 200% or less. Although it may be stretched evenly in the vertical and horizontal directions, it is more preferable to stretch one of the stretch ratios more than the other and stretch the same. Either longitudinal (MD) or lateral (TD) may be increased, but the smaller stretch ratio is preferably 1% or more and 30% or less, more preferably 2% or more and 25% or less, and further preferably 3%. It is 20% or less. The larger draw ratio is 30% to 300%, more preferably 35% to 200%, and still more preferably 40% to 150%. These stretching operations may be performed in one stage or in multiple stages. The draw ratio is determined using the following formula.

Stretch ratio (%) = 100 × {(Length after stretching) − (Length before stretching)} / (Length before stretching)
Such stretching may be performed in the longitudinal direction using two or more pairs of nip rolls with increased peripheral speed on the outlet side (longitudinal stretching), and both ends of the film are gripped by chucks and are orthogonally crossed (longitudinal direction). (Perpendicular direction). Moreover, you may use the simultaneous biaxial stretching method as described in Unexamined-Japanese-Patent No. 2000-37772, Unexamined-Japanese-Patent No. 2001-113591, and Unexamined-Japanese-Patent No. 2002-103445.

  The ratio of Re and Rth can be freely controlled by controlling the value (aspect ratio) obtained by dividing the space between nip rolls by the film width in the case of longitudinal stretching. That is, the Rth / Re ratio can be increased by reducing the aspect ratio. Also, Re and Rth can be controlled by combining longitudinal stretching and lateral stretching. That is, Re can be reduced by reducing the difference between the longitudinal draw ratio and the transverse draw ratio, and Re can be increased by increasing this difference. It is preferable that Re and Rth of the cellulose acylate film thus stretched satisfy the following formula.

Rth ≧ Re,
200 nm ≧ Re ≧ 0 nm,
500 nm ≧ Rth ≧ 30 nm
More preferably, Rth ≧ Re × 1.1,
150 nm ≧ Re ≧ 10 nm,
400nm ≧ Rth ≧ 50nm
More preferably, Rth ≧ Re × 1.2,
100 nm ≧ Re ≧ 20 nm,
350 nm ≧ Rth ≧ 80 nm
The angle θ formed by the film forming direction (longitudinal direction) and the slow axis of Re of the film is preferably closer to 0 °, + 90 °, or −90 °. That is, in the case of longitudinal stretching, it is preferably as close to 0 °, preferably 0 ° ± 3 °, more preferably 0 ° ± 2 °, and further preferably 0 ° ± 1 °. In the case of transverse stretching, 90 ° ± 3 ° or −90 ° ± 3 ° is preferable, more preferably 90 ° ± 2 ° or −90 ° ± 2 °, and still more preferably 90 ° ± 1 ° or −90 ° ±. 1 °.

  As for the thickness of the cellulose acylate film after extending | stretching, 15 micrometers or more and 200 micrometers or less are all preferable, More preferably, they are 30 micrometers or more and 170 micrometers or less, More preferably, they are 40 micrometers or more and 140 micrometers or less. The thickness unevenness is preferably 0% or more and 3% or less in both the longitudinal direction and the width direction, more preferably 0% or more and 2% or less, and further preferably 0% or more and 1% or less.

  The physical properties of the stretched cellulose acylate film are preferably in the following ranges.

The tensile modulus is preferably less than 1.5 kN / mm ² or more 3.0 kN / mm ^2, more preferably 1.7 kN / mm ² or more 2.8 kN / mm ² or less, more preferably 1.8 kN / mm ² or more 2 .6 kN / mm ² or less. The breaking elongation is preferably 3% to 100%, more preferably 5% to 80%, and still more preferably 8% to 50%. Tg (Tg of film, ie, Tg of cellulose acylate and additive) is preferably 95 ° C. or higher and 145 ° C. or lower, more preferably 100 ° C. or higher and 140 ° C. or lower, and still more preferably 105 ° C. or higher and 135 ° C. or lower. is there. The thermal dimensional change at 80 ° C for one day is preferably 0% or more and ± 1% or less in both the vertical and horizontal directions, more preferably 0% or more and ± 0.5% or less, and further preferably 0% or more and ± 0.3% or less. It is. The water permeability at 40 ° C. and 90% is preferably 300 g / m ² · day to 1000 g / m ² · day, more preferably 400 g / m ² · day to 900 g / m ² · day, more preferably 500 g / m. ² · day to 800 g / m ² · day. The equilibrium water content at 25 ° C. and 80% rh is preferably 1% by mass to 4% by mass, more preferably 1.2% by mass to 3% by mass, and still more preferably 1.5% by mass to 2.5% by mass. It is as follows. The thickness is preferably 30 μm to 200 μm, more preferably 40 μm to 180 μm, and still more preferably 50 μm to 150 μm. The haze is 0% to 3%, more preferably 0% to 2%, and still more preferably 0% to 1%.

  The total light transmittance is preferably 90% or more, more preferably 91% or more, and still more preferably 98% or more.

  The unstretched / stretched cellulose acylate film exhibits crystallinity, and an endothermic peak due to crystal melting appears at 170 ° C. to 240 ° C. in a differential thermal analyzer (DSC). The heat of crystal melting is preferably 7 J / g or more and 20 J / g or less.

(9) Surface treatment An unstretched and stretched cellulose acylate film can achieve improved adhesion to each functional layer (for example, a primer layer and a back layer) by performing a surface treatment. For example, glow discharge treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, acid or alkali treatment can be used. The glow discharge treatment here may be low-temperature plasma that occurs under a low pressure gas of 0.1 Pa to 3000 Pa (= 10 ^{−3 to} 20 Torr), and plasma treatment under atmospheric pressure is also preferable. A plasma-excitable gas is a gas that is plasma-excited under the above-mentioned conditions, and examples thereof include chlorofluorocarbons such as argon, helium, neon, krypton, xenon, nitrogen, carbon dioxide, tetrafluoromethane, and mixtures thereof. It is done. Details of these are described in detail on pages 30 to 32 in the Journal of the Invention Association (Technology No. 2001-1745, issued on March 15, 2001, Invention Association). Note that, in the plasma treatment at atmospheric pressure which has been attracting attention in recent years, irradiation energy of 20 Kgy to 500 Kgy is used, for example, under 10 Kev to 1000 Kev, and more preferably, irradiation energy of 20 Kgy to 300 Kgy is used under 30 Kev to 500 Kev. Among these, an alkali saponification treatment is particularly preferable, and it is extremely effective as a surface treatment of a cellulose acylate film. Specifically, methods described in JP-A No. 2003-3266, 2003-229299, 2004-322928, 2005-76088 and the like can be used.

  The alkali saponification treatment may be immersed in a saponification solution or coated with a saponification solution. In the case of the immersion method, it can be achieved by passing an aqueous solution of pH 10 to pH 14 such as NaOH or KOH through a bath heated to 20 ° C. to 80 ° C. for 0.1 to 10 minutes, and then neutralizing, washing with water and drying. .

  In the case of the coating method, a dip coating method, a curtain coating method, an extrusion coating method, a bar coating method, and an E-type coating method can be used. The solvent of the alkali saponification coating solution has good wettability because it is applied to the transparent support of the saponification solution, and the surface state remains good without forming irregularities on the surface of the transparent support by the saponification solution solvent. It is preferred to select a solvent to keep. Specifically, an alcohol solvent is preferable, and isopropyl alcohol is particularly preferable. An aqueous solution of a surfactant can also be used as a solvent. The alkali of the alkali saponification coating solution is preferably an alkali that dissolves in the above solvent, and more preferably KOH or NaOH. The pH of the saponification coating solution is preferably 10 or more, more preferably 12 or more. The reaction conditions during alkali saponification are preferably 1 second to 5 minutes at room temperature, more preferably 5 seconds to 5 minutes, and particularly preferably 20 seconds to 3 minutes. After the alkali saponification reaction, it is preferable to wash the surface on which the saponification solution is applied with water or with an acid and then with water. Further, the coating-type saponification treatment and the alignment film uncoating described later can be performed continuously, and the number of steps can be reduced. Specific examples of these saponification methods include the contents described in JP-A No. 2002-82226 and WO 02/46809.

  It is also preferable to provide an undercoat layer for adhesion to the functional layer. This layer may be coated after the above surface treatment or may be coated without the surface treatment. Details of the undercoat layer are described on page 32 of the Japan Society for Invention and Innovation (Technical Number 2001-1745, published on March 15, 2001, Japan Institute of Invention).

  These surface treatment and undercoating processes can be incorporated at the end of the film forming process, can be performed alone, or can be performed in the functional layer application process described later.

(10) Functional layer imparting The stretched and unstretched cellulose acylate film of the present invention is 32 pages to 45 pages according to the Japan Society for Invention and Technology (public technical number 2001-1745, published on March 15, 2001, Japan Society of Inventions). It is preferable to combine the functional layers described in detail in. Among these, application of a polarizing layer (polarizing plate), application of an optical compensation layer (optical compensation film), application of an antireflection layer (antireflection film), and application of a hard coat layer are preferred.

(I) Application of polarizing layer (creation of polarizing plate)
[Material used for polarizing layer]
Currently, a commercially available polarizing layer is generally produced by immersing a stretched polymer in a solution of iodine or dichroic dye in a bath and allowing iodine or dichroic dye to penetrate into the binder. is there. As the polarizing film, a coating type polarizing film represented by Optiva Inc. can also be used. Iodine and dichroic dye in the polarizing film exhibit deflection performance by being oriented in the binder. As the dichroic dye, an azo dye, stilbene dye, pyrazolone dye, triphenylmethane dye, quinoline dye, oxazine dye, thiazine dye or anthraquinone dye is used. The dichroic dye is preferably water-soluble. The dichroic dye preferably has a hydrophilic substituent (eg, sulfo, amino, hydroxyl). For example, the compound as described in Invention Association public technique, public technical number 2001-1745, page 58 (issue date March 15, 2001) can be mentioned.

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

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

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

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

[Stretching of polarizing film]
The polarizing film is preferably dyed with iodine or a dichroic dye after the polarizing film is stretched (stretching method) or rubbed (rubbing method).

  In the case of the stretching method, the stretching ratio is preferably 2.5 times to 30.0 times, and more preferably 3.0 times to 10.0 times. Stretching can be performed by dry stretching in air. Moreover, you may implement wet extending | stretching in the state immersed in water. The stretch ratio of dry stretching is preferably 2.5 to 5.0 times, and the stretch ratio of wet stretching is preferably 3.0 to 10.0 times. Stretching may be performed in parallel to the MD direction (parallel stretching) or may be performed in an oblique direction (oblique stretching). These stretching operations may be performed once or divided into several times. By dividing into several times, it is possible to stretch more uniformly even at high magnification. More preferred is oblique stretching in which the film is stretched with an inclination of 10 to 80 degrees in the oblique direction.

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

(II) Diagonal Stretching Method A method of stretching using a tenter projecting in an obliquely inclined direction as described in JP-A-2002-86554 can be used. Since this stretching is performed in the air, it is necessary to make it easy to stretch by adding water in advance. The moisture content is preferably 5% to 100%, the stretching temperature is preferably 40 ° C. to 90 ° C., and the humidity during stretching is preferably 50% rh to 100% rh.

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

[Lamination]
A stretched polarizing plate is prepared by laminating the stretched and unstretched cellulose acylate film after saponification and the polarizing layer prepared by stretching. There are no particular restrictions on the direction of bonding, but it is preferable that the direction of the casting axis of the cellulose acylate film and the direction of the stretching axis of the polarizing plate be 0 °, 45 °, or 90 °.

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

  Examples of the laminated layer structure include the following.

B) A / P / A
B) A / P / B
C) A / P / T
D) B / P / B
E) B / P / T
A is an unstretched film of the present invention, B is a stretched film of the present invention, T is a cellulose triacetate film (Fujitack; trade name), and P is a polarizing layer. In the case of the constitutions b) and b), A and B may be the same composition or different cellulose acetates. In the case of the construction d), B may be different in cellulose acetate having the same composition, or may be different in the same draw ratio. In the case of use in a liquid crystal display device, either may be used as the liquid crystal surface, but in the case of configurations b) and e), it is more preferable that B is on the liquid crystal side.

  When incorporating a liquid crystal display device, a substrate containing liquid crystal is usually disposed between two polarizing plates, but it is possible to freely combine a) to e) of the present invention and a normal polarizing plate (T / P / T). it can. However, it is preferable to provide a transparent hard coat layer, an antiglare layer, an antireflection layer, and the like on the film on the outermost surface of the display side of the liquid crystal display device.

  The polarizing plate thus obtained preferably has a higher light transmittance, and preferably has a higher degree of polarization. The transmittance of the polarizing plate is preferably in the range of 30% to 50%, more preferably in the range of 35% to 50%, and in the range of 40% to 50% with respect to light having a wavelength of 550 nm. Is most preferred. The degree of polarization is preferably in the range of 90% to 100%, more preferably in the range of 95% to 100%, and most preferably in the range of 99% to 100% in light having a wavelength of 550 nm. .

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

  A protective film may be bonded to one surface of these polarizing plates, and a separate film may be bonded to the other surface. The protective film and the separate film are used for the purpose of protecting the polarizing plate at the time of shipping the polarizing plate and at the time of product inspection.

(Ii) Application of optical compensation layer (production of optical compensation film)
The optically anisotropic layer is for compensating the liquid crystal compound in the liquid crystal cell in the black display of the liquid crystal display device, and forms an alignment film on the stretched and unstretched cellulose acylate film, and further optically anisotropic It is formed by providing a sex layer.

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

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

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

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

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

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

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

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

  Examples of the crosslinking agent include aldehydes, N-methylol compounds, dioxane derivatives, compounds that act by activating carboxyl groups, active vinyl compounds, active halogen compounds, isoxazole, and dialdehyde starch. Two or more kinds of crosslinking agents may be used in combination. Specific examples include compounds described in paragraphs [0023] to [024] in JP-A No. 2002-62426. Aldehydes having high reaction activity, particularly glutaraldehyde are preferred.

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

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

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

  The alignment film is provided on the stretched / unstretched cellulose acylate film or on the undercoat layer. The alignment film can be obtained by rubbing the surface after crosslinking the polymer layer as described above.

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

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

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

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

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

[Rod-like liquid crystalline molecules]
As rod-like liquid crystalline molecules, azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines , Phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used.

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

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

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

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

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

  As a discotic liquid crystalline molecule, a compound having liquid crystallinity having a structure in which a linear alkyl group, an alkoxy group, and a substituted benzoyloxy group are radially substituted as a side chain of the mother nucleus with respect to the mother nucleus at the center of the molecule Is also included. The molecule or the assembly of molecules is preferably a compound having rotational symmetry and imparting a certain orientation. In the optically anisotropic layer formed from the discotic liquid crystalline molecules, the compound finally contained in the optically anisotropic layer does not need to be a discotic liquid crystalline molecule. Also included are compounds having a group that reacts with heat or light and, as a result, polymerized or cross-linked by reaction with heat or light, resulting in a high molecular weight and loss of liquid crystallinity. Preferred examples of the discotic liquid crystalline molecules are described in JP-A-8-50206. The polymerization of discotic liquid crystalline molecules is described in JP-A-8-27284.

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

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

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

[Other compositions of optically anisotropic layer]
Along with the liquid crystal molecules, a plasticizer, a surfactant, a polymerizable monomer, etc. can be used in combination to improve the uniformity of the coating film, the strength of the film, the orientation of the liquid crystal molecules, and the like. It is preferable that the compound has compatibility with the liquid crystal molecules and can change the tilt angle of the liquid crystal molecules or does not inhibit the alignment.

  Examples of the polymerizable monomer include radically polymerizable or cationically polymerizable compounds. Preferably, it is a polyfunctional radically polymerizable monomer and is preferably copolymerizable with the above-described polymerizable group-containing liquid crystal compound. Examples thereof include those described in paragraph numbers [0018] to [0020] in JP-A No. 2002-296423. The amount of the compound added is generally in the range of 1% by mass to 50% by mass and preferably in the range of 5% by mass to 30% by mass with respect to the discotic liquid crystalline molecules.

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

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

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

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

[Formation of optically anisotropic layer]
The optically anisotropic layer can be formed by applying a coating liquid containing liquid crystalline molecules and, if necessary, a polymerizable initiator described later and optional components on the alignment film.

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

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

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

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

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

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

Light irradiation for polymerizing liquid crystalline molecules is preferably performed using ultraviolet rays. The irradiation energy is preferably in the range of 20 mJ / cm ^{2 to} 50 J / cm ² , and is preferably 20 mJ / cm 2.
More preferably in the range of ² to 5000 mJ / cm ^2, and still more preferably in the range of 100 mJ / cm ² to 800 mJ / cm ^2. In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions. A protective layer may be provided on the optically anisotropic layer.

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

  The inclination angle of the polarizing layer and the optical compensation layer may be stretched so as to match the angle formed between the transmission axis of the two polarizing plates bonded to both sides of the liquid crystal cell constituting the LCD and the vertical or horizontal direction of the liquid crystal cell. preferable. A normal inclination angle is 45 °. Recently, however, devices that are not necessarily 45 ° have been developed for transmissive, reflective, and transflective LCDs, and it is preferable that the stretching direction can be arbitrarily adjusted in accordance with the design of the LCD.

[Liquid Crystal Display]
Each liquid crystal mode in which such an optical compensation film is used will be described.

(TN mode liquid crystal display)
It is most frequently used as a color TFT liquid crystal display device and is described in many documents. The alignment state in the liquid crystal cell in the TN mode black display is an alignment state in which the rod-like liquid crystalline molecules rise at the center of the cell and the rod-like liquid crystalline molecules lie in the vicinity of the cell substrate.

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

  Similarly to the TN mode, the liquid crystal cell in the OCB mode is in a black display, and the alignment state in the liquid crystal cell is such that the rod-like liquid crystalline molecules rise at the center of the cell and the rod-like liquid crystalline molecules lie near the cell substrate. .

(VA mode liquid crystal display device)
The feature is that the rod-like liquid crystalline molecules are oriented substantially vertically when no voltage is applied. In the VA mode liquid crystal cell, (1) the rod-like liquid crystalline molecules are oriented substantially vertically when no voltage is applied. In addition to a narrowly defined VA mode liquid crystal cell (described in JP-A-2-176625) that is aligned substantially horizontally when a voltage is applied, (2) the VA mode is multi-domained to expand the viewing angle ( Liquid crystal cell (in MVA mode) (SID97, Digest of tech. Papers 28 (1997) 845), (3) Rod-like liquid crystal molecules are substantially vertically aligned when no voltage is applied, and twisted A liquid crystal cell in a domain alignment mode (n-ASM mode) (described in the proceedings 58-59 (1998) of the Japanese Liquid Crystal Society) and (4) a SURVAVAL mode liquid crystal cell (LCD interface) Announced at National 98).

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

(Other liquid crystal display devices)
The ECB mode, STN (Supper Twisted Nematic) mode, FLC (Ferroelectric Liquid Crystal) mode, AFLC (Anti-ferroelectric Liquid Crystal) mode, ASM (Axially Symmetric Aligned Microcell) mode are optically based on the same concept as above. Can be compensated for. Further, it is effective in any of a transmissive type, a reflective type, and a transflective liquid crystal display device. It is also advantageously used as an optical compensation sheet for a GH (Guest-Host) type reflective liquid crystal display device.
The detailed uses of these cellulose-based resin films described above are described in detail on pages 45 to 59 in the Japan Society for Invention and Technology (public technical number 2001-1745, published on March 15, 2001, Japan Society for Invention). Has been.

Application of antireflection layer (antireflection film)
The antireflection film generally comprises a low refractive index layer which is also an antifouling layer, and at least one layer having a higher refractive index than that of the low refractive index layer (that is, a high refractive index layer and a medium refractive index layer). It is provided above.

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

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

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

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

[Layer structure of coating type antireflection film]
An antireflection film comprising a layer structure of at least a middle refractive index layer, a high refractive index layer, and a low refractive index layer (outermost layer) on the substrate is designed to have a refractive index satisfying the following relationship.

  Refractive index of high refractive index layer> refractive index of medium refractive index layer> refractive index of transparent support> refractive index of low refractive index layer Alternatively, a hard coat layer is provided between the transparent support and the intermediate refractive index layer. Also good.

  Furthermore, it may consist of a medium refractive index hard coat layer, a high refractive index layer and a low refractive index layer.

  Examples thereof include JP-A-8-122504, JP-A-8-110401, JP-A-10-300902, JP-A-2002-243906, JP-A-2000-11706, and the like. Other functions may be imparted to each layer, for example, an antifouling low refractive index layer or an antistatic high refractive index layer (eg, JP-A-10-206603, JP-A-2002). -243906 publication etc.) etc. are mentioned.

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

[High refractive index layer and medium refractive index layer]
The layer having a high refractive index of the antireflection film is composed of a curable film containing at least an ultrafine particle of an inorganic compound having a high refractive index having an average particle size of 100 nm or less and a matrix binder.

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

  In order to obtain such ultrafine particles, the surface of the particles is treated with a surface treatment agent (for example, silane coupling agents, etc .: JP-A Nos. 1-295503, 11-153703, 2000-9908). Gazette, anionic compound or organometallic coupling agent: JP 2001-310432 A, etc., core-shell structure with high refractive index particles as a core (eg JP 2001-166104 A), specific Dispersing agent combined use (for example, Unexamined-Japanese-Patent No. 11-153703, patent number US6210858B1, Unexamined-Japanese-Patent No. 2002-27776069 etc.) etc. are mentioned.

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

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

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

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

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

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

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

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

For example, paragraph numbers [0018] to [0026] of Japanese Patent Application Laid-Open No. 9-222503, paragraph numbers [0019] to [0030] of Japanese Patent Application Laid-Open No. 11-38220,
Examples include the compounds described in paragraph Nos. [0027] to [0028] of Japanese Patent No. 40284, JP-A 2000-284102, and the like.

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

  The crosslinking or polymerization reaction of the fluorine-containing and / or siloxane polymer having a crosslinking or polymerizable group is performed simultaneously with or after the application of the coating composition for forming the outermost layer containing a polymerization initiator, a sensitizer and the like. It is preferable to carry out by light irradiation or heating.

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

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

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

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

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

[Hard coat layer]
The hard coat layer is provided on the surface of the stretched / unstretched cellulose acylate film in order to impart physical strength to the antireflection film. In particular, it is preferably provided between the stretched / unstretched cellulose acylate film and the high refractive index layer. Moreover, it is also preferable to coat directly on a stretched / unstretched cellulose acylate film without providing an antireflection layer.

  The hard coat layer is preferably formed by a crosslinking reaction or a polymerization reaction of a light and / or heat curable compound. The curable functional group is preferably a photopolymerizable functional group, and the hydrous functional group-containing organometallic compound is preferably an organic alkoxysilyl compound.

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

  Specific examples of the constituent composition of the hard coat layer include those described in JP-A Nos. 2002-144913, 2000-9908, and WO00 / 46617.

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

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

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

  The strength of the hard coat layer is preferably 1H or more, more preferably 2H or more, and most preferably 3H or more in a pencil hardness test according to JIS K5400. Further, in the Taber test according to JIS K5400, the smaller the wear amount of the test piece before and after the test, the better.

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

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

[Other layers]
In addition to the above layers, a primer layer, an antistatic layer, an undercoat layer, a protective layer, and the like may be provided.

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

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

  As a method for forming irregularities on the surface of the antireflection film, any method can be applied as long as these surface shapes can be sufficiently maintained. For example, a method of forming irregularities on the film surface using fine particles in the low refractive index layer (for example, JP 2000-271878 A), a lower layer of the low refractive index layer (high refractive index layer, medium refractive index layer) Alternatively, a relatively large particle (particle size: 0.05 μm to 2 μm) is added to the hard coat layer) to form a surface uneven film, and these shapes are maintained on the surface. And a method of providing a low refractive index layer (for example, JP-A 2000-281410, 2000-95893, 2001-100004, 2001-281407, etc.), uppermost layer (antifouling layer) ) Is physically transferred onto the surface after coating (for example, as an embossing method, JP-A-63-278839, JP-A-11-183710, JP-A-2000-275401). Etc.).

[Usage]
The unstretched and stretched cellulose acylate film of the present invention is an optical film, particularly for a polarizing plate protective film, an optical compensation sheet for a liquid crystal display device (also referred to as a retardation film), an optical compensation sheet for a reflective liquid crystal display device, and a halogenated film. It is useful as a support for silver photographic light-sensitive materials.

(1) Production of polarizing plate (1-1) Stretching An unstretched cellulose acylate film is stretched at 300% / min at a glass transition temperature (Tg) of each film + 10 ° C. As an example of a stretched cellulose acylate film, (1) When the longitudinal stretch ratio is 300% and the lateral stretch ratio is 0%, a film having Re of 200 nm and Rth of 100 nm is obtained. (2) When the longitudinal draw ratio is 50% and the transverse draw ratio is 10%, a film having Re of 60 nm and Rth of 220 nm can be obtained. (3) When the longitudinal draw ratio is 50% and the transverse draw ratio is 50%, a film having Re of 0 nm and Rth of 450 nm is obtained. (4) When the longitudinal draw ratio is 50% and the transverse draw ratio is 10%, a film having Re of 60 nm and Rth of 220 nm can be obtained. (5) When the longitudinal draw ratio is 0% and the transverse draw ratio is 150%, a film having Re of 150 nm and Rth of 150 nm can be obtained.

(1-2) Saponification of Cellulose Acylate Film An unstretched cellulose acylate film and a stretched cellulose acylate film are subjected to the following immersion saponification. Similar results are obtained when coating saponification is performed.

(I) Immersion saponification A 1.5 N aqueous solution of NaOH is used as a saponification solution. The temperature is adjusted to 60 ° C., and the cellulose acylate film is immersed for 2 minutes. Then, after being immersed in a 0.1N sulfuric acid aqueous solution for 30 seconds, it is passed through a water washing bath.

(Ii) Coating saponification 20 parts by mass of water is added to 80 parts by mass of iso-propanol, KOH is dissolved to 1.5 N, and the temperature is adjusted to 60 ° C. and used as a saponification solution. This is coated on a cellulose acylate film at 60 ° C. at 10 g / m ² and saponified for 1 minute. Thereafter, hot water at 50 ° C. is sprayed at 10 L / m ² · min for 1 minute to perform washing.

(1-3) Creation of Polarizing Layer According to Example 1 of JP-A-2001-141926, a circumferential speed difference is given between two pairs of nip rolls, and a polarizing layer having a thickness of 20 μm is prepared by stretching in the longitudinal direction.

(1-4) Bonding The polarizing layer obtained in this way and the saponified unstretched and stretched cellulose acylate film were polarized using PVA (PVA-117H manufactured by Kuraray Co., Ltd.) 3% aqueous solution as an adhesive. The shaft and the cellulose acylate film are laminated so that the longitudinal direction is 45 degrees. The polarizing plate thus prepared is attached to a 20-inch VA liquid crystal display device described in FIGS. 2 to 9 of JP-A-2000-154261 and visually observed from an oblique angle of 32 degrees where the projected parallel stripes are most easily visible. If evaluated, good performance can be obtained.

(2) Production of optical compensation film (i) Unstretched film If the unstretched cellulose acylate film of the present invention is used for the first transparent support of Example 1 of JP-A-11-316378, good optical compensation is achieved. A film can be produced.

(Ii) Stretched cellulose acylate film If the stretched cellulose acylate film of the present invention is used instead of the cellulose acetate film coated with the liquid crystal layer of Example 1 of JP-A-11-316378, a good optical compensation film can be obtained. Can be made. In place of the cellulose acetate film coated with the liquid crystal layer of Example 1 of JP-A-7-333433, an optical compensation filter film can be produced by changing to the stretched cellulose acylate film of the present invention (described as optical compensation film B). A good optical compensation film can be produced.

(3) Production of Low Reflective Film The cellulose acylate film of the present invention was subjected to low reflection using the stretched and unstretched cellulose acylate film of the present invention in accordance with Example 47 of JIII Journal of Technical Disclosure (Technical No. 2001-1745). If a film is produced, good optical performance can be obtained.

(4) Production of Liquid Crystal Display Element The polarizing plate according to the present invention is a liquid crystal display device described in Example 1 of JP-A-10-48420, and a discotic described in Example 1 of JP-A-9-26572. An optically anisotropic layer containing liquid crystal molecules, an alignment film coated with polyvinyl alcohol, a 20-inch VA liquid crystal display device described in FIGS. 2 to 9 of JP-A-2000-154261, and JP-A-2000-154261 The 20-inch OCB type liquid crystal display device shown in FIGS. Furthermore, if the low-reflection film according to the present invention is attached to the outermost layer of these liquid crystal display devices and visual evaluation is performed, good visual recognition performance can be obtained.

  Hereinafter, the present invention will be described in more detail with reference to Experiment 1 to Experiment 10 as examples. The description will be made in detail in Experiment 1, and in other Experiments 2 to 10, the experimental conditions different from Experiment 1 are collectively shown in Table 1. In addition, materials, amounts used, ratios, processing contents, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

[Experiment 1]
(1) Pelletization of cellulose acylate (cellulose acetate propionate) As the cellulose resin, CAP-482-20 (manufactured by Eastman Chemical Co., Ltd.) was used. Hereinafter, it is referred to as CAP. The number average molecular weight of this CAP was 70,000. When preparing CAP pellets, the following additives were added to CAP.
CAP 100 parts by mass Plasticizer: Glycerin diacetate stearate 5 parts by mass Stabilizer: Triphenyl phosphite (TPP) 3 parts by mass The mixture was dried at 100 ° C. for 3 hours to reduce the water content to 0.1 wt% or less.
Matting agent: Silicon dioxide part particles (Aerosil R972V) 0.05 part by weight UV absorber: (2- (2′-hydroxy-3 ′, 5-di-t-butylphenyl) -benzotriazole 0.5 part by weight UV Absorbent: 2,4-hydroxy-4-methoxy-benzophenone
0.1 parts by mass

  The above-mentioned compound was extruded from a die at a screw rotation speed of 300 rpm, a kneading time of 40 seconds and an extrusion rate of 200 kg / hr using a twin-screw kneading extruder with vacuum exhaust, solidified in water at 60 ° C., and then cut to a diameter of 2 mm. A 3 mm cylindrical pellet (CAP pellet) was obtained. In addition, the glass transition temperature Tg of this CAP pellet was 130 degreeC.

(2) Melt film formation CAP pellets were dried at 100 ° C for 5 hours using dehumidified air having a dew point temperature of -40 ° C to make the water content 0.01% by weight or less. This was put into a hopper at 80 ° C. as a film raw material 25 and supplied to the extruder 11. As the extruder 11, a single screw extruder (manufactured by GM Engineering; screw diameter φ50 mm) was used. At 100 mm from the inlet side of the screw of the extruder, oil of Tg-5 ° C. (= about 125 ° C.) of CAP pellets was circulated and cooled inside the screw. The residence time in the barrel of the CAP pellet was adjusted to 5 minutes. The maximum temperature and minimum temperature of the barrel were set at the barrel outlet and inlet, respectively. The CAP pellets were melted in the extruder 11. In the following description, it will be referred to as molten CAP. In this experiment, the position adjusting drum 20 was not used. The melted CAP extruded from the extruder 11 is weighed and sent out by the gear pump 12, and at this time, the rotational speed of the extruder 11 is adjusted so that the melted CAP before the gear pump 12 can be controlled with a constant pressure of 10 MPa. . The molten CAP delivered from the gear pump 12 is filtered through a leaf disk filter having a filtration accuracy of 5 μm, and is passed through a static mixer from a hanger coat die 14 with a slit interval of 0.8 mm at 240 ° C. (hereinafter referred to as sheet-like CAP 26). Extruded). The temperature of the hanger coat die 14 was adjusted to 240 ° C.

  Two infrared heaters (made by Nippon Seeds Co., Ltd .; OHC-15) 15, 16 were provided between the die discharge port 14a and the casting drum 17. The distances L1 and L2 between the infrared heaters 15 and 16 and the sheet-like CAP 26 (also shown as heater arrangement positions L in Table 1) were adjusted to 15 mm. The heating temperature of the infrared heaters 15 and 16 was adjusted to be 300 ° C. The air gap H (mm; distance between the die discharge port 14a and the cast position 17a; see FIG. 2) was 15 mm.

  The sheet-like CAP 26 was solidified with a casting drum 17 having a Tg of −10 ° C. (= about 120 ° C.). The temperature decrease of the sheet-like CAP 26 in the air gap H was −5 ° C. These were measured using thermometers 45 and 46. The temperature at the casting position 17a of the sheet-like CAP 26 was 230 ° C. At this time, electrostatic application was carried out by 10 cm at both ends using an electrostatic application method (a 10 kV wire was placed 10 cm from the position where the melt was cast on the casting drum). The sheet-like CAP 26 was peeled off from the casting drum 17. A film (hereinafter referred to as an unstretched CAP film) 27 was conveyed while being wound around a roller 31 in a cooling zone 30 in which a desired temperature was adjusted. After trimming both ends (each 5% of the total width) just before winding, the both ends were subjected to thicknessing (knurling) with a width of 10 mm and a height of 50 μm, and wound at 3000 m at 5 m / min. The unstretched CAP film 27 thus obtained had a width of 1.5 m and an average thickness of 100 μm.

(3) Evaluation of unstretched CAP film (i) Measurement of film thickness distribution Measurement of thickness unevenness (film thickness distribution) of unstretched CAP film is a continuous thickness meter (TOFU1) manufactured by Yamabun Denshi Co., Ltd. Was used. The thickness at the center of the film was 3 m in the longitudinal direction, and the measurement pitch was measured at 0.5 mm intervals. The film thickness distribution was 1 μm.

(Ii) Measurement of Diese Maximum Depth The measurement of the die stripe depth of the unstretched CAP film was performed using Micromap 123 manufactured by Ryoka System. The maximum die stripe depth was 0.15 μm.

(Iii) Comprehensive evaluation Based on the above results, a comprehensive evaluation of the film was performed in the following four stages.
(Double-circle): It was the film which was very excellent in the optical characteristic and mechanical strength of a film.
○: The film was excellent in optical properties and mechanical strength.
Δ: Although the film had some difficulty in optical properties or mechanical strength, it was a film that could be used depending on the type of product.
X: It was a film which had difficulty in the optical characteristic and mechanical strength of a film, and cannot be used as a product.

  The overall evaluation of the unstretched CAP film obtained in Experiment 1 was a film (◎) with extremely excellent optical characteristics and mechanical strength.

[Experiment 2 to Experiment 7]
The experimental conditions and results of Experiments 2 to 7 are summarized in Table 1. In Experiment 7, a hot air heater (Nippon Seeds Co., Ltd .; DF3) was used instead of the infrared heater. The optical properties and mechanical strength of the unstretched CAP film obtained from Experiment 2 to Experiment 5 satisfying the experimental conditions of the present invention were excellent films (◯). In addition, the unstretched CAP film obtained in Experiment 6 with a wide air gap and Experiment 7 with a large temperature drop, although satisfying the experimental conditions of the present invention, was a film (Δ) with some difficulty.

[Experiment 8 to Experiment 10]
The unstretched CAP film obtained from Experiment 8 and Experiment 9 that does not satisfy the cast position temperature, which is the experimental condition of the present invention, was a film (x) that cannot be used as a product. Further, the unstretched CAP film obtained from Experiment 10 in which no heater was arranged in the air gap was also a film (x) that could not be used as a product.

It is the schematic of the manufacturing line which manufactures the cellulose resin film which concerns on this invention. It is a principal part enlarged view of the manufacturing line shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Film production line, 15, 16 ... Heater, 17 ... Drum for casting, 26 ... Cellulose acylate sheet, 27 ... Cellulose acylate film

Claims (20)

In the method for producing a cellulose resin film in which a film is produced by casting a sheet-like cellulose resin discharged from a die into a sheet shape from a die to a drum,
The film thickness distribution of the cast sheet-like cellulose resin is within 5 μm per 10 m with respect to the longitudinal direction of the film,
And the maximum value of the stripe depth of the at least one surface of the said sheet-like cellulose resin is 1 micrometer or less, The manufacturing method of the cellulose resin film characterized by the above-mentioned. In the method for producing a cellulose resin film, a molten cellulose resin is discharged from a die into a sheet and cast into a drum to produce a film.
A method for producing a cellulose resin film, characterized in that a temperature at the casting position of the cast sheet-like cellulose resin is maintained in a temperature range of 150 ° C. or higher and 230 ° C. or lower.   The method for producing a cellulose resin film according to claim 2, wherein a temperature decrease until the sheet-like cellulose resin discharged from the die is cast to the drum is set to 20 ° C. or less.   The sheet-like cellulose resin is heated so as to be in a range of (solid phase-solid phase transition temperature + 50) ° C. or more (solid phase-solid phase transition temperature + 250) ° C. of the cellulose resin. Item 4. The method for producing a cellulose resin film according to any one of Items 1 to 3.   The method for producing a cellulose resin film according to claim 4, wherein the solid phase-solid phase transition temperature is a glass transition temperature Tg (° C) of the cellulose resin.   The method for producing a cellulose resin film according to any one of claims 1 to 5, wherein the sheet-like cellulose resin is heated by a heater. The distance L1 (mm) between at least one surface of the sheet-like cellulose resin and the surface of the first heater disposed on the one surface side,
It is 10 mm or more and 150 mm or less, The manufacturing method of the cellulose resin film of any one of Claim 1 thru | or 6 characterized by the above-mentioned. A length H1 (mm) in a casting direction in which the first heater heats the sheet-like cellulose resin,
It is 5 mm or more and 300 mm or less, The manufacturing method of the cellulose resin film of Claim 7 characterized by the above-mentioned.   9. The method for producing a cellulose resin film according to claim 7, wherein a second heater is further disposed on a surface opposite to the one surface of the sheet-like cellulose resin. 10. A distance L2 (mm) between the opposite side surface of the sheet-like cellulosic resin and the surface of the second heater,
It is 10 mm or more and 150 mm or less, The manufacturing method of the cellulose resin film of Claim 9 characterized by the above-mentioned. The length H2 (mm) in the casting direction in which the second heater heats the sheet-like cellulose resin,
It is 5 mm or more and 300 mm or less, The manufacturing method of the cellulose resin film of Claim 9 or 10 characterized by the above-mentioned. The heater emits an electromagnetic wave of 0.7 μm or more and 1000 μm or less,
The method for producing a cellulose resin film according to any one of claims 6 to 11, wherein the sheet cellulose resin is heated. When the sheet-like cellulosic resin is cast on the drum,
The method for producing a cellulose resin film according to any one of claims 1 to 12, wherein the sheet-like cellulose resin is leveled on a surface of the drum.   The method for producing a cellulose resin film according to any one of claims 1 to 13, wherein a drum having an arithmetic average roughness (Ra) of a surface of the drum of 0.3 µm or less is used. A method of casting the sheet-like cellulosic resin between two drums,
The cellulosic resin according to any one of claims 1 to 14, wherein a point of arrival of the sheet-like cellulosic resin on another drum is set to a substantially constant position by adjusting a position of the one drum. A method for producing a resin film.   16. The viscosity of the sheet-like cellulose resin is 100 Pa · s or more and 2000 Pa · s or less when measured by a Capillary rheometer method at 25 ° C. and 60% RH. The manufacturing method of the cellulose resin film of any one.   A cellulose resin film produced by the method for producing a cellulose resin film according to claim 1.   A polarizing plate comprising the cellulose resin film according to claim 17.   An optical compensation film comprising the cellulose resin film according to claim 17.   An antireflection film comprising the cellulose resin film according to claim 17.