KR101435975B1 - Thermoplastic resin film and process for producing the same - Google Patents

Abstract

A process for producing a thermoplastic resin film by extruding a thermoplastic resin melted by an extruder (22) into a sheet form on a cooling roller (28) rotating from a die (24) and cooling and solidifying the thermoplastic resin film, when the temperature is the heat loss is to 0.3wt% in the case when allowed to stand for one hour in the atmosphere when said T _0, the extrusion temperature (T ₁₎ at the time of extruding the melt of the thermoplastic resin from said extruder (22) T _{0 to} -40 ° C to T ₀ + 30 ° C; and a step of extruding the extruded thermoplastic resin to a temperature equal to or higher than the extrusion temperature until the extruded thermoplastic resin land on the cooling roller 28 And a heating step of heating the substrate.

Thermoplastic resin film

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic resin film,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic resin film and a manufacturing method thereof, and more particularly to a thermoplastic resin film such as a cellulose resin film having a desired quality for use in a liquid crystal display device and a manufacturing method thereof.

Conventionally, a cellulose resin film is stretched so as to expose a retardation (Re) in a plane and a retardation (Rth) in a thickness direction so as to be used as a retardation film of a liquid crystal display element to enlarge a viewing angle.

As a method of stretching such a cellulose-based resin film, a method of stretching the film in the longitudinal (length) direction (longitudinal stretching), a method of stretching the film in the transverse (width) direction (transverse stretching), or longitudinal stretching and transverse stretching (Simultaneous stretching) can be mentioned. Among them, the longitudinal running has been widely used since the facility is compact. Normally, longitudinal stretching is a method in which a film is heated to a glass transition temperature (Tg) or more between two or more pairs of nip rollers, and the film is stretched in the longitudinal direction by accelerating the conveying speed on the exit side from the conveying speed of the nip roller on the entrance side.

Patent Document 1 discloses a method of longitudinally stretching a cellulose ester. This patent document 1 improves the angular deviation of the slow axis by reversing the longitudinal stretching direction to the direction of the softener film. Patent Document 2 discloses a method in which a nip roller provided between a span having an aspect ratio (L / W) of 0.3 or more and 2 or less is set in a drawing zone and drawn. According to Patent Document 2, the orientation (Rth) in the thickness direction can be improved. The aspect ratio mentioned here refers to a value obtained by dividing the interval L of the nip rollers used for stretching by the width W of the film to be stretched.

Patent Document 1: JP-A-2002-311240

Patent Document 2: JP-A-2003-315551

However, when the cellulose based resin film before stretching (unstretched) is formed by the melt film forming method, since the cellulose resin has a high melt viscosity, the leveling action hardly occurs and the film is stretched in the width direction and in the longitudinal direction The flow direction of the shape resin). If the melt viscosity is high, a stripe failure occurs after being extruded from the die, or the retardation is caused by the residual deformation when the resin is pulled by the cooling drum in a state where the melt viscosity is high.

As measures for preventing the thickness deviation, the stripe failure, and the retardation development, it is effective to lower the viscosity of the extruded resin by increasing the extrusion temperature to be extruded from the die. However, in order to increase the extrusion temperature, The film is exposed to a high temperature, resulting in a problem that the formed film is colored or the strength is lowered due to decomposition of the resin. As described above, the problem of suppressing the thickness deviation, the stripe breakdown and the retardation development, and the problem of suppressing the coloration and the strength reduction are contradictory and can not be solved by the conventional melt film forming technology. Particularly, the cellulose-based resin has lower decomposition temperature and coloring temperature than ordinary thermoplastic resins, and therefore, heating conditions at the time of film formation are difficult.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to solve the problems of suppressing the thickness deviation, the stripe failure and the retardation development, A method for producing a cellulose based resin film capable of improving the yield and a method for producing the cellulose based resin film.

In a first aspect of the present invention, there is provided a method of producing a thermoplastic resin film by extruding a thermoplastic resin melted in an extruder into a sheet form on a rotating cooling roller from a die, (T ₁₎ when the molten thermoplastic resin is extruded from the extruder, and a temperature at which the heat loss becomes 0.30 wt% when the thermoplastic resin is allowed to stand in a nitrogen atmosphere for 1 hour is T ₀ . ) for T ₀ -40 ℃ ~T the extrusion process by extruding a ₀ + 30 ℃, the extruded thermoplastic resin is in the interval up to the landing on the cooling roller, such as the extrusion temperature or higher than the extrusion temperature And a heating step of heating the thermoplastic resin film so as to reach the landing temperature.

According to the first embodiment, the molten thermoplastic resin is extruded at an extrusion temperature (T ₁ ) at the time of extruding the thermoplastic resin from the extruder at a temperature of T ₀ -40 ° C to T ₀ + 30 ° C, It is possible to lower the heat temperature applied to the thermoplastic resin until it is lowered compared with the conventional one, and therefore the resin itself is decomposed and the strength is lowered, and the resin itself is not discolored or removed.

Further, by heating the landing temperature at which the resin is extruded from the die and landed on the cooling roller so that the landing temperature is equal to or higher than the extrusion temperature, and the viscosity of the resin at landing is changed, The moldability and the leveling property of the film can be improved, so that the thickness variation, the stripe failure, and the retardation development can be suppressed. As a result, it is possible to solve the problem of suppressing the thickness deviation, the stripe failure and the retardation development, and the problem of suppressing the coloring and the strength reduction at once, so that it is possible to improve the product quality and the production rate.

In other words, in the first embodiment, the moldability and leveling property of the thermoplastic resin influencing the thickness deviation, the stripe failure, and the retardation development are satisfied only when the thermoplastic resin is satisfied at the landing point at which the thermoplastic resin is landed on the cooling roller, The temperature at which the sheet is exposed to a high temperature is shortened as much as possible by increasing the landing temperature by heating in a short time from the die to the cooling drum and the moldability and leveling property can be satisfied.

The second embodiment of the present invention is characterized in that, in the first embodiment, the upper limit of the landing temperature is T ₁ + 40 ° C.

In the second embodiment, the upper limit of the landing temperature is set to T ₁ + 40 ° C. Even if the temperature is higher than T ₁ + 40 ° C, the time during which the resin is exposed to a high temperature is short, No discoloration or discoloration occurs.

A third embodiment of the present invention is characterized in that, in the first or second embodiment, the thermoplastic resin is a cellulose resin, and T ₁ is 210 ° C to 240 ° C.

The third embodiment relates to the case where the thermoplastic resin is a cellulose resin. The cellulose-based resin has lower decomposition temperature and coloring temperature than ordinary thermoplastic resins, and heating conditions at the time of film formation are difficult, so that the present invention is particularly effective. The reason why T ₁ has a width ranging from 210 ° C to 240 ° C is because T ₁ differs depending on the type of cellulose resin or additive.

A fourth embodiment of the present invention is characterized in that, in the first or second embodiment, the thermoplastic resin is a cyclic olefin resin (for example, cyclic olefin copolymer: COC).

A fifth embodiment of the present invention is characterized in that in the third or fourth embodiment, the thermoplastic resin from the extrusion to the landing is heated with a far infrared heater having a center wavelength of 2.1 to 3.7 m .

According to the fifth embodiment, since the cellulose-based resin is easy to absorb heat having a center wavelength in the range of 2.1 mu m to 3.7 mu m, the temperature of the thermoplastic resin can be efficiently reduced in a short time until it is pushed out from the die and landed on the cooling roller .

In a sixth aspect of the present invention, in any one of the first to fifth embodiments, the thermoplastic resin extruded from the die and landed on the cooling roller is nipped by the cooling roller and the touch roller .

The sixth embodiment relates to a case where the thermoplastic resin extruded from a die and landed on a cooling roller is applied to a touch roller system in which the cooling roller and the touch roller nip the thermoplastic resin. In this case, the thickness variation and the streak defect can be further suppressed by adopting the touch roller method.

According to a seventh aspect of the present invention, in the sixth aspect, the touch roller is an elastic roller.

As the touch roller used in the touch roller method, it is possible to apply a roller having high ordinary rigidity, but the use of the elastic roller can further suppress the occurrence of retardation.

The eighth embodiment of the present invention is characterized in that in the sixth or seventh embodiment, the linear pressure at which the cooling roller and the touch roller nip the sheet-shaped thermoplastic resin is 0.05 to 1.5 MPa do.

The eighth embodiment defines a preferable range of the line pressure to be nipped. By increasing the landing temperature, the thickness deviation and the streak defect of the thermoplastic resin can be continuously lost at a relatively low line pressure, and retardation is also expressed It gets harder.

A ninth embodiment of the present invention is a thermoplastic resin film produced by the manufacturing method according to any one of the first to eighth embodiments.

According to the ninth embodiment, it is possible to obtain a thermoplastic resin film which is suppressed in thickness variation, stripe failure and retardation development, and in which coloration and strength reduction are suppressed.

Effects of the Invention

According to the present invention, there is no decrease in strength and coloring due to deterioration of the cellulose-based resin in the process from the extruder to the die, and also the reduction in the streak defect and the thickness deviation in the process after the discharge from the discharge port of the die The retardation based on the suppression of the residual strain can be reduced and a cellulose-based resin film excellent in product quality can be provided. In addition, such a cellulose resin film can be produced at a high production yield.

1 is a configuration diagram showing a configuration of a film production apparatus to which the present invention is applied,

2 is a schematic view showing a configuration of an extruder,

3 is a perspective view showing a film-forming unit,

4 is a schematic view showing a pair of metal rollers of a film-forming process unit,

5 is a schematic view showing a film-forming unit according to another embodiment,

6 is a configuration diagram showing a configuration of a film production apparatus according to another embodiment to which the present invention is applied,

7 is a schematic view showing a film-forming unit according to another embodiment,

8 is a perspective view showing a film-forming unit according to another embodiment,

9 is a table showing the results of the touch roll method with a line pressure of 0.5 MPa,

10 is a table showing the results of the touch roll method in which the line pressure is changed.

Description of the Related Art

10, 10 ': Film production apparatus 12: Sheet-shaped resin

12 ': cellulose acylate film 14: film forming unit

20: winding means 22: extruder

24: die 24a: die lip

25: heater heating unit 26: roller (elastic roller)

27: cover 28: roller (cooling roller)

28 ': casting roller 44: metal tube (outer tube)

46: Liquid medium layer 48: Elastic body layer (inner tube)

50: metal shaft E: distance of heater heating unit

F: Length of the molten resin in the flow direction Q: Length in contact

Y: film forming speed Z: thickness of outer tube

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, preferred embodiments of a cellulose resin film and a method for producing the same according to the present invention will be described with reference to the accompanying drawings. In the present embodiment, an example of producing a cellulose acylate film is shown, but the present invention is not limited thereto, and the present invention can be applied to the production of a thermoplastic resin film other than a cellulose acylate film. In the present embodiment, a film is formed by a touch roller method in which a resin extruded from a die is sandwiched by a pair of rollers, and the pressing roller is a metal elastic roller. However, the present invention is not limited to this .

Fig. 1 shows an example of a schematic configuration of a cellulose acylate film producing apparatus. 1, the production apparatus 10 mainly comprises a film forming unit 14 for producing a cellulose acylate film 12 'before stretching, a cellulose acylate film 12' produced by the film forming unit 14, , A transverse stretching unit 18 for transversely stretching, and a winding unit 20 for winding up the stretched cellulose acylate film 12 '.

In the film-forming unit 14, the cellulose acylate resin melted in the extruder 22 is discharged in a sheet form from the die 24 and fed between a pair of rotating rollers 26 and 28. The cellulose acylate film 12 'cooled on the roller 28 and solidified is peeled off from the roller 28 and then sequentially sent to the longitudinal stretching machine 16 and the transverse stretch machine 18, And wound in a roll shape by the winding coiler 20. Thereby, the stretched cellulose acylate film 12 'is produced. Hereinafter, the details of each process unit will be described.

2 shows a single screw extruder 22 of the film forming and finishing unit 14. As shown in Fig. 2, the cylinder 32 is provided with a single screw 38 having a flight 36 on the screw shaft 34, and a cellulose acylate resin is supplied from a hopper (40). A supply portion (area denoted by A) for transporting the cellulose acylate resin supplied from the supply port 40 in a quantitative manner in sequence from the supply port 40 side in the cylinder 32, (Area denoted by B) and a metering section (area denoted by C) for weighing the kneaded and compressed cellulose acylate resin. The cellulose acylate resin melted in the extruder 22 is continuously sent from the discharge port 42 to the die 24.

The screw compression ratio of the extruder 22 is set to 2.5 to 4.5, and the L / D is set to 20 to 50. [ Here, the screw compression ratio is expressed by the volume ratio of the supply portion A and the metering portion C, that is, the volume per unit length of the supply portion A / the unit length of the metering portion C, The outer diameter d1 of the shaft 34, the outer diameter d2 of the screw shaft 34 of the metering portion C, the groove portion a1 of the supply portion A and the groove portion a2 of the metering portion C, . L / D is the ratio of the cylinder length L to the cylinder inner diameter D in Fig. The extrusion temperature is set to 190 to 240 캜. When the temperature in the extruder 22 exceeds 240 캜, a cooler (not shown) may be provided between the extruder 22 and the die 24.

If the screw compression ratio is lower than 2.5 and the screw compression ratio is too small, the extruder 22 will not be sufficiently kneaded. If the unmelted portion is generated, the shear heat generation is small, and the melting of the crystal is insufficient As a result, fine crystals tend to remain in the cellulose acylate film after production, and bubbles are likely to be incorporated. As a result, the crystal remaining when the cellulose acylate film 12 'is stretched inhibits the stretchability, and the orientation can not be increased sufficiently. On the other hand, if the screw compression ratio is excessively larger than 4.5, the shearing stress is excessively high and the resin tends to be deteriorated by heat generation, so that the yellowish bead tends to appear in the cellulose acylate film after the production. In addition, if the shear stress is excessively applied, molecular breakage occurs and the molecular weight lowers and the mechanical strength of the film deteriorates. Therefore, the screw compression ratio is preferably in the range of 2.5 to 4.5, more preferably in the range of 2.8 to 4.2, and particularly preferably in the range of 3.0 to 4.0, in order to prevent the yellowish color from coming out from the cellulose acylate film after the production and to make the stretch breaking difficult. Range.

In addition, if L / D is lower than 20 and too small, insufficient melting or insufficient kneading will occur, and similarly to the case where the compression ratio is small, fine crystals tend to remain in the produced cellulose acylate film. On the other hand, if the L / D exceeds 50 and is excessively large, the retention time of the cellulose acylate resin in the extruder 22 becomes excessively long and the resin tends to deteriorate. Further, when the retention time is prolonged, molecular breakage occurs, resulting in a decrease in molecular weight and a decrease in the mechanical strength of the film. Therefore, the L / D ratio is preferably in the range of 20 to 50, more preferably in the range of 22 to 45, and particularly preferably in the range of 24 to 40, in order to prevent yellowing of the cellulose acylate film after the production, Range.

The extrusion temperature of the cellulose acylate resin extruded from the die is T ₀ -40 캜 when the temperature at which the heat sensitivity of the cellulose acylate resin is 0.30 wt% when the cellulose acylate resin is left in the nitrogen atmosphere for 1 hour is T ₀ ~ T ₀ + 30 캜. Here, the method of measuring the amount of heat loss is measured as a reduction amount of the volatile low molecular weight component generated by the thermal decomposition of the cellulose acylate resin in a state where heat is applied for 60 minutes at a predetermined temperature in a nitrogen atmosphere. More specifically, the temperature is elevated under a condition of atmospheric pressure under a condition of atmospheric pressure at 25 ° C to a predetermined temperature at a rate of 50 ° C per minute, and then the temperature is maintained at a predetermined temperature for 60 minutes. (Weight of the cellulose acylate resin at a predetermined temperature of 0 minutes) - (weight of the cellulose acylate resin at a predetermined temperature for 60 minutes) of the cellulose acylate resin decreased by pyrolysis during 60 minutes at the predetermined temperature The weight of the resin) is determined, and the reduction rate from the weight of the cellulose acylate resin in the state before heating is calculated by the following formula.

(expression)

(Heat loss wt%) =

(((Weight after holding of predetermined temperature 0 minute) - (weight after 60 minutes after holding prescribed temperature)) / (weight before heating)) 100

In the case of the cellulose acylate resin, if the temperature at which the cellulose acylate resin is extruded from the die is lower than 200 캜 and too low, the crystal becomes insufficiently melted and fine crystals are likely to remain in the cellulose acylate film after the production, The stretchability is deteriorated and the orientation can not be sufficiently increased. On the other hand, if the temperature when extruded from the die exceeds 260 占 폚 and is excessively high, the cellulose acylate resin deteriorates and the degree of yellowishness (YI value) deteriorates. Therefore, from the viewpoint that the yellow color is hardly produced in the cellulose acylate film after production and that it is difficult to break the stretch, T ₁ is in the range of 200 ° C to 260 ° C, preferably in the range of 210 ° C to 250 ° C, 220 < 0 > C to 240 < 0 > C.

The cellulose acylate resin is melted using the extruder 22 constructed as described above, and the molten resin is continuously supplied to the die 24 and discharged in the form of a sheet from the front end (lower end) of the die 24. It is preferable that the zero shear viscosity of the cellulose acylate resin when discharged is 2000 Pa · sec or less. If the zero shear viscosity exceeds 2000 Pa · sec, the molten resin discharged from the die spreads largely immediately after the discharge, and is liable to adhere to the tip portion of the die, which is liable to be contaminated and to have a streak defect. The discharged sheet-like resin 12 is fed and nipped between a pair of rollers 26 and 28 (see Fig. 1).

Figs. 3 and 4 show one embodiment of the touch roller system in the present invention. One pair of rollers 26 and 28 is constituted by a metal elastic roller 26 and the other roller is a cooling roller 28. [ The surfaces of the rollers 26 and 28 are mirror-finished or semi-mirror-finished, and the arithmetic average height Ra is 100 nm or less, preferably 50 nm or less, more preferably 25 nm or less . The rollers 26 and 28 are configured to control the surface temperature thereof, and the surface temperature can be controlled by circulating a liquid medium such as water in the rollers 26 and 28, for example. Among the pair of rollers 26 and 28, the roller 26 is formed to have a diameter smaller than that of the other roller 28, and the surface thereof is made of a metal material, and the surface temperature thereof can be precisely controlled . Then, the pair of rollers 26 and 28 rotate at the same surface speed.

The sheet-like resin 12 of the cellulose acylate resin extruded from the die 24 is fed between a pair of rotating rollers 26 and 28, The temperature at the time of extrusion is equal to or higher than the extrusion temperature. The reason for this is that film formation of the cellulose acylate film in such a temperature range can suppress the development of the thickness deviation of the film, in particular, the occurrence of the thickness deviation in the film flow direction, and the retardation can be reduced. Therefore, the temperature at which the cellulose acylate film extruded from the die 24 landed on the intersection of the elastic roller 26 and the cooling roller 28 is in the temperature range of T _{1 to} T ₁ + 40 ° C desirable. The reason is that when the temperature of the sheet-like resin 12 at the time of landing on the intersection of the elastic roller 26 and the cooling roller 28 is excessively high relative to the extrusion temperature, the viscosity becomes too low, ) Itself becomes loose and becomes unstable. In this case, the temperature of the sheet-like resin 12 is more preferably T ₁ + 30 캜 or less, and more preferably T ₁ + 20 캜 or less.

In order to form the film with the temperature of the sheet-like resin 12 within the above-mentioned range, for example, as shown in Figs. 3 and 4, when the film is fed from the die 24 onto the cooling roller 28 Shaped resin 12 are heated by the heater heating units 25 and 25, respectively. It is preferable that the width dimension of the heater heating unit is at least 1.0 times, preferably at least 1.2 times, the width of the rib 24a of the die 24, and the roller length of the cooling roller 28 is the upper limit. The distance (the distance from the uppermost portion to the lowermost portion of the heater heating unit 25) to the flow direction of the sheet-like resin 12 of the heater heating unit 25 is E, the length in the flow direction of the sheet- F, it is preferable that the E / F is set to 10% to 90% from the viewpoint of efficiently heating the sheet-like resin 12. The length F in the flow direction of the sheet-like resin 12 is preferably 100 mm to 900 mm from the viewpoint of efficiently heating the sheet-like resin 12. The heater heating unit 25 has a short length until the cellulose acylate resin is extruded from the die 24 as the sheet resin 12 and landed on the intersection of the elastic roller 26 and the cooling roller 28 From the viewpoint of effectively raising the temperature of the sheet-like resin 12 within a period of time, it is preferable to use an out-of-round heater having a center wavelength in the range of 2.1 mu m to 3.7 mu m.

Fig. 4 shows an embodiment of a pair of rollers 26, 28. Fig. The elastic roller 26 is composed of a metal barrel (outer barrel) 44, a liquid medium layer 46, an elastic body layer (inner barrel) 48, and a metal shaft 50 which form an outer shell from the outer layer have. The outer cylinder 44 and the inner cylinder 48 of the elastic roll 26 rotate by the rotation of the cooling roll 28 which is in contact through the sheet-like molten resin. The elastic roller 26 receives a reaction force from the cooling roller 28 through the sheet and forms a concave shape along the surface of the cooling roller 28. [ . Therefore, the elastic roller 26 and the cooling roller 28 come into surface contact with the sheet, and the sheet sandwiched by the northermal force, in which the shape of the resiliently deformed elastic roller 26 returns to its original state, And cooled in the cooling roller 28. [ It is preferable that the metal cylinder 44 is made of a metal thin film and has a seamless structure without welded joints. The thickness Z of the metal cylinder 44 is preferably in the range of 0.05 mm < Z < 7.0 mm. Here, when the outer tube thickness Z of the elastic roller is 0.05 mm or less, the north tractive force is small and the surface quality improvement effect is not obtained, and the roller strength is weakened. On the other hand, if it is more than 7.0 mm, the elasticity can not be obtained and the effect of eliminating the residual deformation is not obtained. Although the thickness Z of the metal cylinder 44 satisfies 0.05 mm <Z <7.0 mm, it is more preferable that 0.2 mm <Z <5.0 mm.

In addition, the glass transition temperature of the cellulose acylate resin [Tg (℃)] - When called X (℃) the temperature (℃) of the elastic roller (26), Y the film-forming rate ^{(m / min), 0.0043X 2} +0.12 The film forming speed Y and the temperature of the roller (elastic roller) 26 are preferably set so as to satisfy X + 1.1 < Y < 0.019X ² + 0.73X + 24. When the film forming speed Y is 0.0043X ² + 0.12X + 1.1 or less, the pressing time is excessively long and residual strain is developed in the film. When the film forming speed Y is 0.019X ² + 0.73X + 24 or more, The film can not be slowly cooled and stuck to the elastic roller 26. As a result, The temperature of the cooling roller 28 is preferably within ± 20 ° C., more preferably within ± 15 ° C., and more preferably ± 10 ° C. with respect to the temperature of the elastic roller 26.

The line pressure P (MPa) is represented by P (MPa) when the elastic roller 26 and the cooling roller 28 of the pair of rollers 26 and 28 sandwich the sheet-like cellulose acylate resin, But is preferably 0.05 to 1.5 MPa. If the line pressure [P (MPa)] is less than 0.05 MPa, the pressing force for pressing the resin in the planar shape is too small to improve the surface shape. If P So that deformation occurs and the retardation is developed.

The cellulose acylate resin discharged by discharging the cellulose acylate resin from the die 24 has a slight liquid accumulation (bank) between the pair of rollers 26 and 28 And this cellulose acylate resin is squeezed by a pair of rollers 26 and 28 so that the sheet is formed while its thickness is adjusted. At this time, the elastic roller 26 receives a reaction force from the cooling roller 28 through the cellulose acylate resin and elastically deforms in a concave shape along the surface of the cooling roller 28, and the cellulose acylate resin is pressed against the elastic roller 26 and the chill rollers 28. As shown in Fig. Then, when the film 12 'is squeezed by the rollers 26 and 28 that satisfy the above-mentioned conditions and the thickness (Z), temperature, line pressure, and cooling length of the outer cylinder are satisfied, no stripe failure occurs, Of the cellulose acylate film 12 'and the residual deformation is suppressed, so that the cellulose acylate film 12' suitable for an optical film having a small retardation can be produced. Further, according to the film forming and finishing unit 14 constructed as described above, the film thickness is 20 to 300 m, the retardation (Re) in the plane is 20 nm or less, and the retardation (Rth) in the thickness direction is 20 nm or less. The film 12 'can be produced.

Here, the retardation (Re, Rth) is determined by the following equation.

Re (nm) = n (MD) -n (TD) x T (nm)

R (nm) = (n (MD) + n (TD)) / 2} -n (TH)

In the formulas, n (MD), n (TD) and n (TH) represent the refractive index in the length (flow) direction, the width direction and the thickness direction, and T represents the thickness in nm.

The film 12 'squeezed by the pair of rollers 26 and 28 is wound and cooled by a roller 28 made of metal and then peeled off from the surface of the roller 28 to be fed to the longitudinally- .

It is also conceivable to cover the sheet-like resin 12 and the heater heating unit 25 with a cover 27 having a heat insulating function and / or a heat reflecting function, as shown in Fig. As described above, the sheet-like resin 12 and the heater heating unit 25 from the die 24 to the contact on the cooling roller 26 are covered with the cover 27 having the heat insulating function and / or the heat reflecting function It is possible to effectively suppress the temperature distribution in the width direction of the sheet-like resin and suppress the occurrence of the thickness variation of the film.

In addition, the present invention can be applied not only to a case where a film is formed by a touch roller method in which a resin extruded from a die is sandwiched by a pair of rollers (see Fig. 1) The film is formed by a casting drum method in which a resin extruded from a casting roller 28 'is cooled by a casting roller 28'.

8, the heater heating unit 25 is provided on only one side of the sheet-like resin 12 to heat at least one surface of the sheet-like resin 12 to form the sheet-like resin 12 Of the film 12 'is in contact with the casting roller 28' can be made to be within the temperature obtained by adding 40 DEG C to the deterioration-point temperature, so that the thickness variation of the film 12 'can be suppressed.

Hereinafter, the stretching process up to the time of stretching the cellulose acylate film 12 'produced by the film forming unit 14 and producing the stretched cellulose acylate film 12' will be described.

Stretching of the cellulose acylate film 12 'is carried out in order to orient molecules in the cellulose acylate film 12' and to express in-plane retardation (Re) and thickness-direction retardation (Rth).

As shown in Fig. 1 or 6, the cellulose acylate film 12 'is longitudinally stretched in the longitudinal direction in the longitudinal stretching machine 16 first. After the cellulose acylate film 12 'is preheated, the cellulose acylate film 12' is wound around the two nip rolls 30 and 31 in a heated state. The nip roll 31 on the exit side carries the cellulose acylate film 12 'at a faster conveying speed than the nip roll 30 on the entrance side, whereby the cellulose acylate film 12' .

The preheating temperature in the longitudinal drawing machine 16 is preferably Tg-40 DEG C or more and Tg + 60 DEG C or less, more preferably Tg-20 DEG C or more and Tg + 40 DEG C or less, Deg.] C or less. The drawing temperature of the longitudinal drawing machine 16 is preferably not less than Tg and not more than Tg + 60 占 폚, more preferably not less than Tg + 2 占 폚 and not more than Tg + 40 占 폚, more preferably not less than Tg + Or less. The draw ratio in the longitudinal direction is preferably 1.0 or more and 2.5 or less, more preferably 1.1 or more and 2 or less.

The longitudinally stretched cellulose acylate film 12 'is sent to the transverse stretching machine 18 and transversely stretched in the transverse direction. In the transverse stretching machine 18, for example, a tenter can be suitably used, and both end portions of the cellulose acylate film 12 'in the width direction are held by clips by the tenter and stretched in the transverse direction. By this transverse stretching, the retardation (Rth) can be further increased.

The transverse stretching is preferably carried out using a tenter, and a preferable stretching temperature is not less than Tg and not more than Tg + 60 占 폚, more preferably not less than Tg + 2 占 폚 and not more than Tg + 40 占 폚, + 4 ° C or higher, and Tg + 30 ° C or lower. The draw ratio is preferably 1.0 or more and 2.5 or less, more preferably 1.1 or more and 2.0 or less. After transverse stretching, it is preferable to alleviate the stretching in either the longitudinal or transverse direction or both. This makes it possible to reduce the distribution of the slow axis in the width direction.

By such stretching, Re is preferably 0 nm or more and 500 nm or less, more preferably 10 nm or more and 400 nm or less, still more preferably 15 nm or more and 300 nm or less, Rth is 0 nm or more and 500 nm or less Is not less than 50 nm and not more than 400 nm, and more preferably not less than 70 nm and not more than 350 nm.

Among these, Re? Rth is more preferable, and still more preferable that Re? 2? Rth is satisfied. In order to realize such high Rth and low Re, it is preferable to stretch the stretched film in the transverse (width) direction as described above. That is, the difference in the orientation in the longitudinal direction and in the transverse direction becomes the retardation difference Re in the plane, but when the difference in the vertical and horizontal orientations is further reduced by stretching in the transverse direction which is orthogonal to the longitudinal direction, Can be made smaller. On the other hand, since the area magnification increases by stretching in the transverse direction in addition to the longitudinal direction, the orientation in the thickness direction increases with decreasing thickness, and Rth can be increased.

In addition, it is preferable that the variation in the width direction of Re and Rth by the place in the longitudinal direction is 5% or less, more preferably 4% or less, further preferably 3% or less.

As described above, according to the present embodiment, since the resin can be extruded from the die 24 into a sheet at an extrusion temperature lower than the degradation point temperature, which is the temperature causing the deterioration of the cellulose acylate resin, It does not cause the strength to drop or discolor.

According to the present embodiment, the landing temperature at which the sheet is extruded from the die 24 and landed on the cooling roller 26 is set to be equal to or higher than the extrusion temperature, and the temperature of the cellulose acylate resin The viscosity is lowered and the moldability and leveling property of the resin are improved, so that the thickness deviation, the stripe failure, and the retardation development can be suppressed. As a result, it is possible to suppress the thickness variation, the stripe breakdown, and the retardation development, as well as to suppress the coloring and the strength drop, and to improve the product quality and the yield rate at the same time.

Hereinafter, the cellulose acylate resin and the processing method of the cellulose acylate film suitable for the present invention will be described in detail in order.

(1) a plasticizer

It is preferable to add a polyhydric alcohol-based plasticizer to the resin for producing the cellulose acylate film in the present invention. Such a plasticizer not only lowers the modulus of elasticity but also has an effect of reducing the difference in crystallinity of the front and back.

The content of the polyhydric alcohol-based plasticizer is preferably 2 to 20% by weight based on the cellulose acylate. The content of the polyhydric alcohol plasticizer is preferably from 2 to 20% by weight, more preferably from 3 to 18% by weight, and still more preferably from 4 to 15% by weight.

If the content of the polyhydric alcohol plasticizer is less than 2% by weight, the above effect can not be sufficiently achieved. On the other hand, when the content is more than 20% by weight, flow-down (surface precipitation of the plasticizer) occurs.

Polyvalent alcohol plasticizers that can be specifically used in the present invention include glycerin esters such as glycerin esters and diglycerin esters, which have good compatibility with cellulose fatty acid esters and exhibit a remarkable thermoplastic effect, glycerin ester compounds such as polyethylene glycol and polypropylene glycol , A compound in which an acyl group is bonded to the hydroxyl group of the polyalkylene glycol, and the like.

Specific examples of glycerin esters include glycerin diacetate stearate, glycerin diacetate palmitate, glycerin diacetate misalteate, glycerine diacetate laurethate, glycerine diacetate caprate, glycerine diacetate nonanoate, glycerine diacetate octanoate, glycerine di But are not limited to, acetate heptanoate, glycerine diacetate hexanoate, glycerine diacetate pentanoate, glycerin diacetate oleate, glycerin acetate dicaprate, glycerin acetate dinonanate, glycerin acetate dioctanoate, glycerin acetate deptanoate, Glycerin acetate dicaproate, glycerin acetate divalvalate, glycerin acetate dibutylate, glycerin dipropionate caprate, glycerin dipropionate Glycerin dipropionate palmitate, glycerin dipropionate stearate, glycerin dipropionate oleate, glycerin tributylate, glycerin tripentanoate, glycerin monopalmate, glycerin monopalmitate, Glycerin monostearate, glycerin distearate, glycerin propionate raulate, glycerin oleate propionate, etc., but not limited thereto, and they may be used alone or in combination.

Among these, glycerin diacetate caprylate, glycerin diacetate ferulogonate, glycerin diacetate caprate, glycerin diacetate laurethate, glycerin diacetate myristate, glycerine diacetate palmitate, glycerin diacetate stearate, glycerin diacetate Oleate is preferred.

Specific examples of diglycerol esters include diglycerin tetraacetate, diglycerin tetra propionate, diglycerin tetrabutyrate, diglycerin tetravalerate, diglycerin tetrahexanoate, diglycerin tetraheptanoate, diglycerin tetracapryl Diglycerin tetracarboxylate, diglycerin triacetate propionate, diglycerin triacetate butyrate, di &lt; RTI ID = 0.0 &gt; Glycerin triacetate valerate, diglycerin triacetate hexanoate, diglycerin triacetate heptanoate, diglycerin triacetate caprylate, diglycerin triacetate ferargonate, diglycerin triacetate Diglycerin triacetate dipalmitate, diglycerin triacetate dipropionate, diglycerin triacetate dipropionate, diglycerin triacetate dipropionate, diglycerin triacetate dipropionate, diglycerin triacetate dipropionate, But are not limited to, diacetate dibutylate, diglycerine diacetate divarate, diglycerin diacetate dihexanoate, diglycerin diacetate diheptanoate, diglycerin diacetate dicaprylate, diglycerin diacetate difelarate, diglycerin di But are not limited to, acetate dicaprate, diglycerin diacetate diarylate, diglycerin diacetate dimyristate, diglycerin diacetate dipalmitate, diglycerin diacetate distearate, diglycerin diacetate diolate, Diglycerin acetate tributyrate, diglycerin acetate tributyrate, diglycerin acetate tricaprate, diglycerin acetate tributyrate, diglycerin acetate tributyrate, diglycerin acetate trivaleate, diglycerin acetate trihexanoate, diglycerin acetate triheptanoate, diglycerin acetate tricaprylate, diglycerin acetate tri Diglycerin acetate tristearate, diglycerin acetate trioleate, diglycerin acetate tristearate, diglycerin acetate tristearate, diglycerin acetate triacetate, diglycerin acetate trioleate, diglycerin acetate trioleate, , Diglycerin stearate, diglycerin caprylate, diglycerin myristate, and diglycerin esters such as diglycerol oleate. However, the present invention is not limited to these, It can be used in combination.

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

Specific examples of polyalkylene glycols include polyethylene glycol and polypropylene glycol having an average molecular weight of 200 to 1000, but not limited thereto, and these may be used alone or in combination.

Specific examples of the compound having an acyl group bonded to the hydroxyl group of the polyalkylene glycol include polyoxyethylene acetate, polyoxyethylene propionate, polyoxyethylene butyrate, polyoxyethylene valerate, polyoxyethylene caproate, polyoxyethylene Heptanoate, polyoxyethylene octanoate, polyoxyethylene nonanoate, polyoxyethylene caprate, polyoxyethylene laurethate, polyoxyethylene myristate, polyoxyethylene palmitate, polyoxyethylene stearate, polyoxyethylene There may be mentioned polyolefins such as ethylene oleate, polyoxyethylene linoleate, polyoxypropylene acetate, polyoxypropylene propionate, polyoxypropylene butyrate, polyoxypropylene barrelate, polyoxypropylene caproate, polyoxypropylene heptanoate, Propylene octanoate, poly Polyoxypropylene stearate, polyoxypropylene stearate, polyoxypropylene oleate, polyoxypropylene linoleate, and the like may be added to the polyolefin resin composition of the present invention. But they are not limited to these, and they can be used alone or in combination.

In order to sufficiently exhibit the above effects of these polyhydric alcohols, it is preferable to melt-form cellulose acylate under the following conditions. That is, the pellets obtained by mixing the cellulose acylate and the polyhydric alcohol are melted in an extruder and extruded from a T die to form a film. However, the extruder outlet temperature (T2) is preferably higher than the extruder inlet temperature (T1) (T3) to be higher than T2. That is, the temperature is preferably increased as the melting proceeds. This is because when the temperature is suddenly raised from the inlet, the polyhydric alcohol is first dissolved and liquefied. In this case, the cellulose acylate becomes suspended, insufficient seaweed can not be received from the screw, and an insoluble product is generated. The reason that such sufficient mixing does not proceed is that the effect of the plasticizer as described above can not be exhibited and the effect of suppressing the difference in the front and back of the melt film after melt extrusion can not be obtained. In addition, such a defective solution becomes a fish eye-shaped foreign matter 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 surface of the film and observing it in a screen shape. Also, the fish eye causes tailing at the die exit and increases the die line.

T1 is preferably 150 to 200 占 폚, more preferably 160 to 195 占 폚, and still more preferably 165 to 190 占 폚. T2 is preferably in the range of 190 to 240 캜, more preferably 200 to 230 캜, and still more preferably 200 to 225 캜. It is important that these melting temperatures (T1, T2) are 240 DEG C or less. If this temperature is exceeded, the modulus of elasticity of the film-forming film tends to increase. This is considered to be because decomposition occurs in the cellulose acylate due to melting at a high temperature, which causes crosslinking to increase the modulus of elasticity. The die temperature T3 is preferably less than 200 to 235 DEG C, more preferably 205 to 230 DEG C, and still more preferably 205 DEG C or more and 225 DEG C or less.

(2) Stabilizer

In the present invention, it is preferable to use either or both of a phosphite compound and a phosphorous ester compound as a stabilizer. As a result, deterioration with 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 to 0.5 wt%, more preferably 0.01 to 0.4 wt%, and still more preferably 0.02 to 0.3 wt%.

(I) a phosphite-based stabilizer

The specific phosphite-based coloring preventing agent is not particularly limited, but a phosphite-based coloring preventing agent represented by the following general formulas (1) to (3) is preferable.

R ' and R ' n + 1 are independently selected from the group consisting of hydrogen, alkyl of 4 to 23 carbon atoms, aryl, alkoxy Alkyl, aryloxyalkyl, alkoxyaryl, arylalkyl, alkylaryl, polyaryloxyalkyl, polyalkoxyalkyl, and polyalkoxyaryl groups, provided that each of the groups represented by general formulas (1), In the phosphite-based coloring preventing agent represented by the general formula (2), X 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 k and q each represent an integer of 1 or more and p represents an integer of 3 or more.

The number of k and q in these phosphite-based coloring preventing agents is preferably 1 to 10. Since the number of k and q is 1 or more, the volatility upon heating becomes small, and when it is 10 or less, the compatibility with cellulose acetate propionate is improved, which is preferable. The value of p is preferably 3 to 10. 3 or more, the volatility at the time of heating becomes small, and when it is 10 or less, the compatibility with cellulose acetate propionate is improved, which is preferable.

As specific examples of the phosphite-based coloring preventing agent represented by the following general formula (4), those represented by the following chemical formulas (5) to (8) are preferable.

Specific examples of the phosphite-based coloring preventing agent represented by the following general formula (9) are preferably those represented by the following formulas (10), (11) and (12).

(Ii) Phosphorus ester stabilizer

Examples of the phosphorous ester stabilizer include cyclic neopentane tetraylbis (octadecyl) phosphite, cyclic neopentane tetraylbis (2,4-di-t-butylphenyl) phosphite, cyclic neopentane tetra (2,6-di-t-butylphenyl) octylphosphite, tris (2,4-di -t-butylphenyl) phosphite, and the like.

(Iii) Other stabilizers

A weak organic acid, a thioether compound, an epoxy compound and the like may be incorporated as a stabilizer.

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

Examples of the thioether compound include, for example, dilauryl thiodipropionate, ditridecyl thiodipropionate, dimyristyl thiodipropionate, distearyl thiodipropionate, palmityl stearyl thiodipropane And phonate. These may be used alone, or two or more of them may be used in combination.

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

(3) Cellulose acylate

&Quot; Cellulose acylate resin &quot;

(Composition and degree of substitution)

The cellulose acylate used in the present invention is preferably a cellulose acylate satisfying all of the requirements expressed by the following formulas (1) to (3).

2.0? A + B? 3.0 Equation (1)

0? A? 2.0 (2)

1.0? B? 2.9 (3)

(In the above formulas (1) to (3), A represents the degree of substitution of the acetate group and B represents the total sum of degree of substitution of the propionate group, the butyrate group, the pentaamino group and the hexanoyl group.)

Preferably,

2.0? A + B? 3.0 Equation (4)

0? A? 2.0 Equation (5)

1.2? B? 2.9 Equation (6)

More preferably,

2.4? A + B? 3.0 Equation (7)

0.05? A? 1.7 (8)

1.3 &lt; / = B &lt; / =

More preferably,

2.5? A + B? 2.95 Equation (10)

0.1? A? 1.55 (11)

1.4? B? 2.85 (12)

In this way, a propionate group, a butyrate group, a pentanoyl group and a hexanoyl group are introduced into the cellulose to form a cellulose acylate. Such a range is preferable because the melting temperature can be lowered and the thermal decomposition due to the melt film formation can be suppressed. On the other hand, if the temperature is outside the range, the melting temperature and the thermal decomposition temperature become close to each other, and it becomes difficult to suppress the thermal decomposition, which is not preferable.

These cellulose acylates may be used alone or in combination of two or more. It may also be a mixture of polymer components other than cellulose acylate.

Next, the method for producing the cellulose acylate used in the present invention will be described in detail. Regarding the raw material surface and synthesis method of the cellulose acylate of the present invention, it is described in detail on pages 7 to 12 of the Inventor Association Open Publication (Air No 2001-1745, published on Mar. 15, 2001, Invention Society).

(Raw materials and pretreatment)

As the cellulose raw material, those derived from a broad-leaved pulp, a softwood pulp, and a cotton linter are preferably used. As the cellulose raw material, it is preferable to use one having a high purity such that the content of? -Cellulose is 92 mass% or more and 99.9 mass% or less.

In the case where the cellulose raw material is in the form of a film or a lump, it is preferable to preliminarily pulverize the cellulose raw material, and it is preferable that the cellulose is in the form of a pulp until the form of the cellulose is fluff.

(Activation)

It is preferable that the cellulose raw material is subjected to treatment (activation) in which it is brought into contact with the activating agent prior to acylation. As the activating agent, a carboxylic acid or water can be used. However, in the case of using water, dehydration may be performed by adding an excess of an acid anhydride after activation, or washing with carboxylic acid to replace water, Or the like. The activator may be added at a controlled temperature, and the addition method may be selected from a method such as spraying, dropping, and dipping.

Preferred carboxylic acids as the activating agent are carboxylic acids having 2 to 7 carbon atoms (e.g., acetic acid, propionic acid, butyric acid, 2-methylpropionic acid, valeric acid, 3-methylbutyric acid, 2- methylbutyric 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, 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, a catalyst for acylation such as sulfuric acid may be further added, if necessary. However, the addition of a strong acid such as sulfuric acid may accelerate the depolymerization, so that the addition amount is preferably about 0.1% by mass to 10% by mass relative to the cellulose. Two or more kinds of activating agents 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 with respect to cellulose. If the amount of the activating agent is not lower than the lower limit value described above, the problem of the degree of activation of the cellulose is not lowered. The upper limit of the amount of the activator to be added is not particularly limited as far as productivity is not impaired, but is preferably 100 times or less by mass, more preferably 20 times or less, and particularly preferably 10 times or less, in mass with respect to cellulose. The activation agent may be added to the cellulose in an excessively large amount to effect activation, and then the operation may be performed by filtration, blow-drying, heat drying, vacuum distillation, solvent replacement, or the like to reduce the amount of the activator.

The activation time is preferably 20 minutes or more, and the upper limit is not particularly limited as long as it does not affect productivity, but is preferably 72 hours or less, more preferably 24 hours or less, particularly preferably 12 hours or less to be. The activation temperature is preferably 0 ° C to 90 ° C, more preferably 15 ° C to 80 ° C, and particularly preferably 20 ° C to 60 ° C. The activation of the cellulose may be carried out under pressure or reduced pressure. As a heating means, an electromagnetic wave such as a microwave or an infrared ray may be used.

(Acylation)

In the method for producing the cellulose acylate in the present invention, acylation of the hydroxyl group of the cellulose by adding an acid anhydride of carboxylic acid to the cellulose and reacting with bronsted acid or Lewis acid as a catalyst desirable.

Examples of the method for obtaining the cellulose mixed acylate include a method of reacting two carboxylic acid anhydrides as an acylating agent by mixing or sequential addition, a method of mixing a mixed acid anhydride of two carboxylic acids (for example, acetic acid / ), A method in which a mixed acid anhydride (for example, acetic acid / propionic acid mixed acid anhydride) is synthesized in a reaction system using a carboxylic acid and an acid anhydride of another carboxylic acid (for example, acetic acid and propionic anhydride) , A method of once synthesizing a cellulose acylate having a degree of substitution of less than 3, and further acylating the remaining hydroxyl group using an acid anhydride or an acid halide.

(Acid anhydride)

As the acid anhydrides of carboxylic acids, the number of carbon atoms as the carboxylic acid is preferably 2 to 7, and examples thereof include acetic anhydride, propionic anhydride, butyric anhydride, 2-methylpropionic acid anhydride, valeric acid anhydride, 3-methylbutyric anhydride , 2-methylvaleric acid anhydride, 4-methylvaleric acid anhydride, 2,2-dimethyl (2-methylbutyric anhydride), 2-methylbutyric anhydride, 2,2-dimethylpropionic acid anhydride Butyric anhydride, 2,3-dimethylbutyric anhydride, 3,3-dimethylbutyric anhydride, cyclopentanecarboxylic anhydride, heptanoic anhydride, cyclohexanecarboxylic anhydride, benzoic anhydride and the like. More preferred are anhydrides such as acetic anhydride, propionic anhydride, butyric anhydride, valeric anhydride, hexanoic anhydride, and heptanoic anhydride, particularly preferably acetic anhydride, propionic anhydride and butyric anhydride.

For the purpose of preparing a mixed ester, it is preferable to use these acid anhydrides in combination. The mixing ratio thereof is preferably determined according to the substitution ratio of the objective mixed ester. The acid anhydride is usually added to the cellulose in an excess equivalent amount. That is, the amount is preferably 1.2 to 50 equivalents, more preferably 1.5 to 30 equivalents, and particularly preferably 2 to 10 equivalents, based on the hydroxyl group of the cellulose.

(catalyst)

Bronsted acid or Lewis acid is preferably used as the catalyst for acylation used in the production of cellulose acylate in the present invention. The definitions of Bronsted acid and Lewis acid are described, for example, in the fifth edition (2000) of "Physicochemical Dictionary". Examples of preferred Bronsted acids include sulfuric acid, perchloric acid, phosphoric acid, methanesulfonic acid, benzenesulfonic acid, and p-toluenesulfonic acid. Examples of preferred Lewis acids include zinc chloride, tin chloride, antimony chloride, magnesium chloride and the like.

As the catalyst, sulfuric acid or perchloric acid is more preferable, and sulfuric acid is particularly preferable. The amount of the catalyst to be added is preferably 0.1 to 30 mass%, more preferably 1 to 15 mass%, and particularly preferably 3 to 12 mass% with respect to cellulose.

(menstruum)

In the acylation, a solvent may be added for the purpose of adjusting the viscosity, the reaction rate, the crosslinking property, the acyl substitution ratio and the like. As such a solvent, dichloromethane, chloroform, carboxylic acid, acetone, ethyl methyl ketone, toluene, dimethyl sulfoxide, sulfolane or the like may be used, but carboxylic acid is preferable. For example, Carboxylic acids such as 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, , 3-methylvaleric acid, 4-methylvaleric acid, 2,2-dimethylbutyric acid, 2,3-dimethylbutyric acid, 3,3-dimethylbutyric acid and cyclopentanecarboxylic acid}. More preferred are acetic acid, propionic acid, butyric acid and the like. These solvents may be mixed and used.

(Conditions of acylation)

The acylation may be carried out by mixing an acid anhydride with a catalyst and, if necessary, a solvent, followed by mixing with cellulose, and these may be mixed with cellulose in a continuous manner. Usually, a mixture of an acid anhydride and a catalyst, It is preferred that the mixture of solvents is adjusted as an acylating agent and then reacted with cellulose. It is preferable to cool the acylating agent in advance in order to suppress the temperature rise in the reaction vessel due to the heat of reaction at the time of acylation. The cooling temperature is preferably -50 ° C to 20 ° C, more preferably -35 ° C to 10 ° C, and particularly preferably -25 ° C to 5 ° C. The acylating agent may be added in the form of a liquid, or may be added as a solid in the form of crystals, flakes or blocks by freezing.

The acylating agent may also be added to the cellulose at one time or dividedly. Cellulose may be added to the acylating agent at one time or dividedly. When the acylating agent is added in divided portions, acylating agents having the same composition may be used or different acylating agents having different compositions may be used. As a preferable example, 1) a mixture of an acid anhydride and a solvent is firstly added and then a catalyst is added, 2) an acid anhydride, a mixture of a solvent and part of a catalyst is firstly added, and then a mixture of the rest of the catalyst and the solvent is added 4) a solvent is added first, and a mixture of an acid anhydride and a catalyst or a mixture of an acid anhydride, a catalyst and a solvent is added , And so on.

Acylation of cellulose is an exothermic reaction, but in the method of producing cellulose acylate of the present invention, it is preferable that the maximum attained temperature at acylation is 50 캜 or less. If the reaction temperature is lower than this temperature, depolymerization proceeds and it is preferable because no problem occurs that it is difficult to obtain a cellulose acylate having a polymerization degree suitable for the use of the present invention. The maximum attained temperature at the time of acylation is preferably 45 DEG C or lower, more preferably 40 DEG C or lower, particularly preferably 35 DEG C or lower. The reaction temperature may be controlled by using a temperature controller or may be controlled by the initial temperature of the acylating agent. The reaction vessel can be depressurized to control the reaction temperature by the heat of vaporization of the liquid component in the reaction system. Since heat generation at the time of acylation is large at the initial stage of the reaction, it is possible to perform control such as cooling at the beginning of the reaction and then heating. The end point of the acylation can be determined by means such as light transmittance, solution viscosity, temperature change of the reaction system, solubility of the reaction product in an organic solvent, and observation with a polarizing microscope.

The minimum temperature of the reaction is preferably -50 ° C or higher, more preferably -30 ° C or higher, and particularly preferably -20 ° C or higher. The preferable acylation time is 0.5 hour to 24 hours, more preferably 1 hour to 12 hours, and particularly preferably 1.5 hours to 6 hours. If the reaction time is less than 0.5 hour, the reaction does not proceed sufficiently under normal reaction conditions, and if it exceeds 24 hours, it is not preferable for industrial production.

(Reaction terminator)

In the method for producing the cellulose acylate used in the present invention, it is preferable to add a reaction terminator after the acylation reaction.

As the reaction terminator, any acid anhydride may be used as long as it decomposes the acid anhydride, and preferred examples thereof include water, alcohol (for example, ethanol, methanol, propanol, isopropyl alcohol, etc.) or a composition containing them. The reaction terminator may contain a neutralizing agent to be described later. When the reaction terminator is added, a large amount of heat exceeding the cooling capability of the reaction apparatus is generated, which may cause a decrease in the degree of polymerization of the cellulose acylate, or that the cellulose acylate may precipitate in an undesired form It is preferable to add a mixture of carboxylic acid and water such as acetic acid, propionic acid, butyric acid and the like rather than adding water or alcohol directly, and acetic acid is particularly preferable as the carboxylic acid. The composition ratio of the carboxylic acid and water can be used in an arbitrary ratio, but the content of water is more preferably in the range of 5% by mass to 80% by mass, further preferably in the range of 10% by mass to 60% by mass, and more preferably in the range of 15% Particularly preferred.

Even if the reaction terminator is added to the reaction vessel for acylation, the reaction may be added to the vessel of the reaction terminator. It is preferable to add the reaction terminator over 3 minutes to 3 hours. If the addition time of the reaction terminator is 3 minutes or more, the exothermic heat becomes excessively large, which causes a problem of lowering the polymerization degree, insufficient hydrolysis of the acid anhydride, lowering the stability of the cellulose acylate, and the like . When the addition time of the reaction terminator is 3 hours or less, there is no problem such as a decrease in industrial productivity, which is preferable. The addition time of the reaction terminator is preferably from 4 minutes to 2 hours, more preferably from 5 minutes to 1 hour, and particularly preferably from 10 minutes to 45 minutes. When the reaction terminator is added, it is not necessary to cool the reaction vessel even if it is cooled. However, for the purpose of suppressing depolymerization, it is preferable to cool the reaction vessel to suppress the temperature rise. It is also preferable to cool the reaction terminator.

(corrector)

After the reaction stopping step of acylation or the reaction stopping step of acylation, a neutralizing agent (for example, a dehydrating agent, a dehydrating agent, etc.) for hydrolysis of an excess carboxylic anhydride remaining in the system, Carbonate, acetate, hydroxide or oxide of calcium, magnesium, iron, aluminum or zinc) or a solution thereof may be added. Examples of the solvent for the neutralizing agent include water, alcohols (e.g., ethanol, methanol, propanol, isopropyl alcohol), carboxylic acids (e.g., acetic acid, propionic acid, butyric acid, etc.), ketones (e.g., acetone, ethyl methyl ketone, , A polar solvent such as dimethylsulfoxide, and a mixed solvent thereof.

(Partial hydrolysis)

The cellulose acylate thus obtained has a degree of total substitution of about 3. However, in order to obtain a degree of substitution with a desired degree of substitution, a small amount of a catalyst (usually an acylation catalyst such as sulfuric acid remaining) and water The ester bond is partially hydrolyzed by keeping it for several days to several days, and the degree of acyl substitution of the cellulose acylate is reduced to a desired degree (so-called maturation) in general. Since the sulfuric acid ester of cellulose is also hydrolyzed in the course of partial hydrolysis, the amount of sulfuric acid ester bound to cellulose can be reduced by controlling the conditions of hydrolysis.

It is preferable that the catalyst remaining in the system at the time when the desired cellulose acylate is obtained is completely neutralized with the neutralizing agent or the solution as described above to stop the partial hydrolysis. It is also preferable to effectively remove a catalyst (for example, sulfuric acid ester) bound in a solution or in a solution by adding a neutralizing agent (for example, magnesium carbonate, magnesium acetate or the like) for producing a salt having a low solubility in the reaction solution.

(percolation)

It is preferable to perform filtration of the reaction mixture (dope) for the purpose of removing or reducing unreacted substances, defoluble salts and other foreign substances in the cellulose acylate. The filtration may be performed in any process from completion of acylation to re-precipitation. For the purpose of control of filtration pressure and handling property, it is also preferable to dilute with an appropriate solvent before filtration.

(Reprecipitation)

The cellulose acylate thus obtained is mixed in a poor solvent such as water or an aqueous solution of a carboxylic acid (for example, acetic acid, propionic acid, etc.), or a poor solvent is mixed in a cellulose acylate solution to reprecipitate the cellulose acylate, The intended cellulose acylate can be obtained by washing and stabilizing treatment. The re-precipitation may be performed continuously or batchwise by a predetermined amount. It is also desirable to control the shape and molecular weight distribution of the re-precipitated cellulose acylate by adjusting the concentration of the cellulose acylate solution and the composition of the poor solvent according to the substitution or degree of polymerization of the cellulose acylate.

(washing)

The resulting cellulose acylate is preferably washed. The washing solvent may be any solvent as long as the cellulose acylate has low solubility and can remove impurities, but usually water or warm water is used. The temperature of the washing water is preferably 25 to 100 캜, more preferably 30 to 90 캜, particularly preferably 40 to 80 캜. The cleaning process may be performed in a so-called batch mode in which filtration and replacement of the cleaning liquid are repeated, or may be performed using a continuous cleaning device. It is also preferable that the waste solution generated in the process of re-precipitation and washing is reused as a poor solvent in the re-precipitation process, or a solvent such as a carboxylic acid is recovered by means such as distillation and reused.

The washing may be carried out by any means, but examples thereof include hydrogen ion concentration, ion chromatography, electrical conductivity, ICP, elemental analysis, and atomic absorption spectroscopy.

By this treatment, a catalyst (such as sulfuric acid, perchloric acid, trifluoroacetic acid, p-toluenesulfonic acid, methanesulfonic acid or zinc chloride) in the cellulose acylate, a neutralizing agent (such as a carbonate of calcium, magnesium, iron, aluminum or zinc, A reaction product of a neutralizing agent and a catalyst, a carboxylic acid (acetic acid, propionic acid, butyric acid, etc.), a reaction product of a neutralizing agent and a carboxylic acid, and the like, which are effective for increasing the stability of cellulose acylate Do.

(stabilize)

The cellulose acylate after washing by hot water treatment may be treated with a weak alkali (for example, a carbonate, a bicarbonate, a hydroxide, an oxide or an oxide such as sodium, potassium, calcium, magnesium or aluminum) to further improve the stability or lower the odor of the carboxylic acid Or the like) or the like.

The amount of residual impurities can be controlled depending on the amount of the cleaning liquid, the temperature and time of the cleaning, the stirring method, the shape of the cleaning vessel, and the composition and concentration of the stabilizer. In the present invention, conditions for acylation, partial hydrolysis, and washing are set so that the residual sulfuric acid muscle amount (as sulfur atom content) is 0 to 500 ppm.

(dry)

In the present invention, it is preferable to dry the cellulose acylate in order to adjust the moisture content of the cellulose acylate to a desired amount. The method of drying is not particularly limited as far as the desired water content can be obtained. However, it is preferable to perform the drying method efficiently by using means such as heating, blowing, decompression, and agitation singly or in combination. The drying temperature is preferably 0 to 200 캜, more preferably 40 to 180 캜, and particularly preferably 50 to 160 캜. The water content of the cellulose acylate of the present invention is preferably 2% by mass or less, more preferably 1% by mass or less, and particularly preferably 0.7% by mass or less.

(shape)

The cellulose acylate of the present invention may take various forms such as particulate, powder, fibrous, lumpy and the like, but it is preferable that the raw material of the film is a particulate or powdery form. Therefore, after drying, Crushing or squeezing may be performed for improvement. When the cellulose acylate is in a particulate form, it is preferable that at least 90 mass% of the particles used have a particle diameter of 0.5 to 5 mm. It is also preferable that at least 50 mass% of the particles used have a particle diameter of 1 to 4 mm. It is preferable that the cellulose acylate particles have a shape which is as close to a sphere as possible. The apparent density of the cellulose acylate particles of the present invention is preferably 0.5 to 1.3, more preferably 0.7 to 1.2, and particularly preferably 0.8 to 1.15. The apparent density measurement method is specified in JIS K-7365.

The cellulose acylate particles of the present invention preferably have an angle of repose of 10 to 70 degrees, more preferably 15 to 60 degrees, and particularly preferably 20 to 50 degrees.

(Degree of polymerization)

The degree of polymerization of the cellulose acylate preferably used in the present invention has an average degree of polymerization of 100 to 300, preferably 120 to 250, and more preferably 130 to 200. The average degree of polymerization can be measured by an intrinsic viscosity method (Udakazuo, Hideo Saito, Textile Journal, Vol. 18, No. 1, pp. 105-120, 1962) such as Ueda and measurement of molecular weight distribution by gel permeation chromatography (GPC) Can be measured by a method. Further, it is described in detail in Japanese Patent Laid-Open No. 9-95538.

In the present invention, the weight average degree of polymerization / number average degree of polymerization of the cellulose acylate by GPC is preferably 1.6 to 3.6, more preferably 1.7 to 3.3, and particularly preferably 1.8 to 3.2.

These cellulose acylates may be used alone or in combination of two or more. It may also be a mixture of polymer components other than cellulose acylate. The polymer component to be mixed is preferably excellent in compatibility with the cellulose ester, and has a transmittance of 80% or more, more preferably 90% or more, and more preferably 92% or more, in a film.

[Synthesis example of cellulose acylate]

Examples of the synthesis of the cellulose acylate used in the present invention are described in detail below, but the present invention is not limited thereto.

Synthesis Example 1 (Synthesis of cellulose acetate propionate)

150 g of cellulose (hardwood pulp) and 75 g of acetic acid were taken in a 5 L separable flask equipped with a reflux condenser as a reaction vessel and vigorously stirred for 2 hours while heating in an oil bath adjusted to 60 캜. The pretreated cellulose was swollen and shattered and showed a fluff shape. The reaction vessel was cooled in an ice-water bath at 2 캜 for 30 minutes.

Separately, a mixture of 1545 g of propionic acid anhydride and 10.5 g of sulfuric acid as an acylating agent was prepared, cooled to -30 DEG C, and added to the reaction vessel containing the pretreated cellulose in one portion at once. After a lapse of 30 minutes, the temperature of the external equipment was gradually raised, and the internal temperature was adjusted to 25 캜 after 2 hours from the addition of the acylating agent. The reaction vessel was cooled in an ice-water bath at 5 캜, and after 0.5 hour from the addition of the acylating agent, the internal temperature was adjusted to 10 캜, and the internal temperature was adjusted to 23 캜 after 2 hours. Lt; / RTI &gt; The reaction vessel was cooled in an ice water bath at 5 캜 and 120 g of 25% by mass aqueous acetic acid cooled to 5 캜 was added over 1 hour. The internal temperature was raised to 40 DEG C and stirred for 1.5 hours. Subsequently, a solution of magnesium acetate tetrahydrate in 50% by mass of acetic acid and 2-times molar amount of sulfuric acid was added to the reaction vessel, followed by stirring for 30 minutes. 1 L of 25% by weight aqueous acetic acid, 500 mL of 33% by weight aqueous acetic acid, 1 L of 50% by weight aqueous acetic acid and 1 L of water were added in this order to precipitate cellulose acetate propionate. Precipitation of the obtained cellulose acetate propionate was carried out by washing with hot water. The washing conditions at this time were changed as shown in Table 1 to obtain cellulose acetate propionate having residual sulfate ion radicals varied in amount. After washing, the mixture was stirred in an aqueous 0.005% by mass calcium hydroxide solution at 20 캜 for 0.5 hour, further washed with water until the pH of the washing liquid reached 7, and then vacuum dried at 70 캜.

The cellulose acetate propionate obtained by 1 H-NMR and GPC measurement had an acetylation degree of 0.30, a degree of propionylation of 2.63, and a degree of polymerization of 320. [ The content of sulfuric acid muscle was measured by ASTM D-817-96.

Synthesis Example 2 (Synthesis of cellulose acetate butyrate)

100 g of cellulose (hardwood pulp) and 135 g of acetic acid were placed in a 5 L separable flask equipped with a reflux condenser as a reaction vessel, and allowed to stand for 1 hour while being heated in an oil bath adjusted to 60 캜. Then, the mixture was vigorously stirred for 1 hour while heating in an oil bath adjusted to 60 ° C. The pretreated cellulose was swollen and shattered and showed a fluff shape. The reaction vessel was placed in an ice water bath at 5 캜 for 1 hour to sufficiently cool the cellulose.

Separately, a mixture of 1080 g of butyric acid anhydride and 10.0 g of sulfuric acid as an acylating agent was prepared, cooled to -20 캜 and added to the reaction vessel containing the pretreated cellulose in one portion. After a lapse of 30 minutes, the temperature of the external equipment was raised to 20 ° C and the reaction was carried out for 5 hours. The reaction vessel was cooled in an ice-water bath at 5 캜, and 2400 g of 12.5% by mass hydrous acetic acid cooled to about 5 캜 was added over 1 hour. The internal temperature was raised to 30 DEG C and the mixture was stirred for 1 hour. Then, 100 g of a 50% by mass aqueous solution of magnesium acetate tetrahydrate was added to the reaction vessel, and the mixture was stirred for 30 minutes. 1000 g of acetic acid and 2500 g of 50% by weight aqueous acetic acid were slowly added to precipitate cellulose acetate butyrate. Precipitation of the obtained cellulose acetate butyrate was carried out by washing with warm water. The washing conditions at this time were changed as shown in Table 1 to obtain cellulose acetate butyrate in which the amount of residual sulfuric acid muscle was changed. After washing, the mixture was stirred in an aqueous 0.005% by mass calcium hydroxide solution for 0.5 hour, washed with water until the pH of the washing liquid reached 7, and dried at 70 ° C. The obtained cellulose acetate butyrate had an acetylation degree of 0.84, a degree of butyrylation of 2.12, and a degree of polymerization of 268.

(4) Other additives

(I)

It is preferable to add fine particles as a matting agent. Examples of the fine particles used in the present invention include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate and calcium phosphate. The fine particles contain silicon, which is preferable because turbidity can be lowered, 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 / l or more. It is more preferable that the average diameter of the primary particles is as small as 5 to 16 nm because the haze of the film can be lowered. The apparent specific gravity is preferably 90 to 200 g / L or more, more preferably 100 to 200 g / L or more. The larger the specific gravity of the outer appearance, the higher the concentration of the dispersion becomes, and the haze and agglomerates become better.

These fine particles usually form secondary particles having an average particle diameter of 0.1 to 3.0 占 퐉. These fine particles exist as agglomerates of primary particles in the film and form irregularities of 0.1 to 3.0 占 퐉 on the surface of the film. The secondary average particle diameter is preferably 0.2 탆 or more and 1.5 탆 or less, more preferably 0.4 탆 or more and 1.2 탆 or less, and most preferably 0.6 탆 or more and 1.1 탆 or less. The primary and secondary particle diameters were determined by observing the particles in the film with a scanning electron microscope and measuring the diameter of the circle circumscribing the particles. In addition, 200 particles were observed by moving the place, and the mean value was referred to as the average particle diameter.

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

Of these, AEROSIL 200V and AEROSIL R972V are fine particles of silicon dioxide having a primary average particle diameter of 20 nm or less and an apparent specific gravity of 70 g / L or more and lowering the friction coefficient while maintaining the turbidity of the optical film at a low level Which is particularly preferable.

(Ii) Other additives

(For example, a hydroxybenzophenone compound, a benzotriazole compound, a salicylic acid ester compound, a cyanoacrylate compound, etc.), an infrared absorber, an optical modifier, a surfactant And an odor trap agent (amine, etc.)) can be added. Details of these materials are preferably those described in detail in the Inventors Association Open Publication No. 2001-1745 (published on Mar. 15, 2001, Invention Society), p. 17-22.

As the infrared absorbing dye, for example, those disclosed in Japanese Patent Application Laid-Open No. 2001-194522 can be used. As the ultraviolet absorbing agent, for example, those described in Japanese Patent Application Laid-Open No. 2001-151901 can be used. By mass to 5% by mass.

As the optical adjusting agent, a retardation adjusting agent can be exemplified. For example, those described in Japanese Patent Application Laid-Open Nos. 2001-166144, 2003-344655, 2003-248117 and 2003-66230 can be used. The retardation Re in the plane and the retardation Rth in the thickness direction can be controlled. The preferable amount of addition is 0 to 10 wt%, more preferably 0 to 8 wt%, and still more preferably 0 to 6 wt%.

(5) Properties of the cellulose acylate mixture

The cellulose acylate mixture (cellulose acylate, plasticizer, stabilizer, and other additives mixed) preferably satisfies the following physical properties.

(I) weight reduction

The thermoplastic cellulose acetate propionate composition of the present invention has a heat loss rate of less than 5% by weight at 220 캜. Here, the weight loss rate refers to the weight loss rate at 220 占 폚 when the sample is heated from room temperature at a heating rate of 10 占 폚 / min under a nitrogen gas atmosphere. By using the cellulose acylate mixture, the heat loss rate can be set to 5 wt% or less. More preferably 3% by weight or less, further preferably 1% by weight or less. By doing so, it is possible to suppress a failure (generation of bubbles) that occurs during film formation.

(Ii) Melt viscosity

The thermoplastic cellulose acetate propionate composition of the present invention preferably has a melt viscosity at 220 ° C and 1 sec ^-1 of 100 to 1000 Pa · sec, more preferably 200 to 800 Pa · sec, still more preferably 300 to 700 Pa · sec. With such a high melt viscosity, it is possible to prevent an increase in optical anisotropy (retardation) caused by stretching orientation without increasing (stretching) by the tension at the die exit.

Such adjustment of the viscosity may be achieved by any method, but can be achieved by, for example, polymerization degree of cellulose acylate and the amount of additives such as plasticizer.

(6) Pelleting

It is preferable that the cellulose acylate and the additive are mixed and pelletized before the melt film formation.

In carrying out the pelletization, it is preferable to dry the cellulose acylate and additives in advance, but it may be substituted by using a vent type extruder. As the drying method, a method of heating at 90 DEG C for 8 hours or more in a heating furnace can be used, but the present invention is not limited thereto. The pelletization can be carried out by melting the cellulose acylate and the additive by using a biaxial kneading extruder at a temperature of not less than 150 ° C and not more than 250 ° C, extruding the mixture in a funnel shape, and solidifying the mixture in water. Further, it may be cut while extruding directly from the spinneret in the water after melting by the extruder, or may be pelletized by the under water cutting method or the like.

As long as sufficient melt kneading can be obtained, the extruder may be any known single screw extruder, non-meshing type two-axis screw extruder, meshing type two-axis screw extruder, An extruder or the like can be used.

The preferred size of pellets is not less than 1 mm 2 and not more than 300 mm 2 in cross-sectional area and not less than 1 mm and not more than 30 mm in length, more preferably not less than 2 mm 2 and not more than 100 mm 2, and not less than 1.5 mm and not more than 10 mm.

Further, when pelletization is carried out, it is also possible to add the additive from a raw material inlet or a vent in the middle of the extruder.

The number of revolutions of the extruder is preferably 10 rpm or more and 1000 rpm or less, more preferably 20 rpm or more and 700 rpm or less, further preferably 30 rpm or more and 500 rpm or less. If the rotation speed is slower than this, the residence time is prolonged, and the molecular weight is lowered due to heat deterioration, and the yellowish color tends to be deteriorated, which is not preferable. In addition, if the rotation speed is too high, molecular breakdown tends to occur due to shearing, which leads to a decrease in molecular weight or to the generation of cross-linked gel.

The extrusion retention time in the pelletization is 10 seconds or more and 30 minutes or less, more preferably 15 seconds or more and 10 minutes or less, and further preferably 30 seconds or more and 3 minutes or less. If sufficient melting is possible, a shorter residence time is preferable in that the resin deterioration and the occurrence of yellowish color can be suppressed.

(7) Melting film

(I) drying

It is preferable to use pellets obtained by the above-mentioned method, and it is preferable to reduce the water content in the pellets prior to the melt-film formation.

In the present invention, it is preferable to dry the cellulose acylate in order to adjust the moisture content of the cellulose acylate to a desired amount. The drying method is often carried out using a dehumidifying air dryer, but it is not particularly limited as long as it can obtain a desired water content (heating, blowing, decompression, stirring, etc.) More preferably, the drying hopper is preferably an insulating structure). The drying temperature is preferably 0 to 200 占 폚, more preferably 40 to 180 占 폚, and particularly preferably 60 to 150 占 폚. If the drying temperature is too low, it takes a long time to dry, and the moisture content is not lower than the target value, which is not preferable. On the other hand, if the drying temperature is too high, the resin will stick and block, which is undesirable. The drying air volume is preferably 20 to 400 m 3 / hour, more preferably 50 to 300 m 3 / hour, particularly preferably 100 to 250 m 3 / hour. If the drying air volume is small, the drying efficiency is poor, which is not preferable. On the other hand, even if the air volume is large, the improvement of the drying effect is less economical than a certain amount. The dew point of air is preferably 0 to -60 占 폚, more preferably -10 to -50 占 폚, particularly preferably -20 to -40 占 폚. The drying time is at least 15 minutes, more preferably at least 1 hour, particularly preferably at least 2 hours. On the other hand, even if drying is performed for more than 50 hours, there is less effect of reducing the moisture content and there is a fear of thermal deterioration of the resin, so that it is not desirable to make the drying time unnecessarily long. The water content of the cellulose acylate of the present invention is preferably 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 above-mentioned cellulose acylate resin is fed into the cylinder through a feed port of an extruder (separate from the pelletizing extruder). (Region A) for quantitatively transporting the cellulose acylate resin supplied from the supply port, a compression section (region B) for melt-kneading and compressing the cellulose acylate resin, a melt-kneaded and compressed cellulose And a metering section (area C) for measuring the acylate resin. It is preferable to dry the resin in order to reduce the water content by the above-mentioned method. However, in order to prevent the oxidation of the molten resin due to the remaining oxygen, the resin is extruded in an inert (nitrogen or the like) It is more preferable to carry out the evacuation. The screw compression ratio of the extruder is set to 2.5 to 4.5, and the L / D is set to 20 to 70. [ Here, the screw compression ratio is expressed by the volume ratio of the supply part A and the metering part C, that is, the volume per unit length of the supply part A / the unit length of the metering part C, The outer diameter d1 of the metering section C and the outer diameter d2 of the screw shaft of the metering section C as well as the groove section a1 of the supply section A and the groove section a2 of the metering section C. L / D is the ratio of the cylinder length to the cylinder inner diameter. The extrusion temperature is set to 190 to 240 캜. If the temperature in the extruder exceeds 240 캜, a cooler may be provided between the extruder and the die.

If the screw compression ratio is less than 2.5 and is too small, melt-kneading is not sufficiently carried out to cause an unmelted portion, or the shear heat generation is too small to melt the crystal insufficiently, and fine crystals tend to remain in the produced cellulose acylate film , And bubbles are easily mixed. As a result, the strength of the cellulose acylate film is lowered, or the crystal remaining when the film is stretched inhibits the stretchability and the orientation can not be sufficiently increased. On the other hand, if the screw compression ratio is excessively large at a value exceeding 4.5, shearing stress is excessively applied and the resin tends to be deteriorated by heat generation, so that the yellowish color tends to appear in the produced cellulose acylate film. In addition, if the shear stress is excessively applied, molecular breakage occurs and the molecular weight lowers and the mechanical strength of the film deteriorates. Therefore, the screw compression ratio is preferably in the range of 2.5 to 4.5, more preferably in the range of 2.8 to 4.2, and particularly preferably in the range of 3.0 to 3.0, in order to prevent the yellow color from coming out from the cellulose acylate film after the production, Lt; / RTI &gt;

Further, if L / D is lower than 20 and too small, insufficient melting or insufficient kneading occurs, and similarly to the case where the compression ratio is small, fine crystals tend to remain in the produced cellulose acylate film. On the other hand, if L / D is over 70, excessively large, the retention time of the cellulose acylate resin in the extruder becomes excessively high, and the resin tends to deteriorate. Further, if the retention time is prolonged, molecular breakdown occurs or the molecular weight decreases, and the mechanical strength of the cellulose acylate film decreases. Therefore, in order to prevent yellowish color from appearing in the cellulose acylate film after production, and also to have a strong film strength and to make stretching difficult to break, L / D is preferably in the range of 20 to 70, more preferably in the range of 22 to 65, And particularly preferably in the range of 24 to 50.

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

Here, the haze is an index indicating whether the extrusion temperature is too low, in other words, whether or not the crystals remaining in the cellulose acylate film after production are large and small. If the haze exceeds 2.0%, the strength of the cellulose acylate film It is likely to cause deterioration and breakage at the time of stretching. The yellow index (YI value) is an index for determining whether the extrusion temperature is excessively high. If the yellow index (YI value) is 10 or less, there is no problem in terms of yellowiness.

As a kind of the extruder, a single-screw extruder, which is generally inexpensive in terms of facility cost, is often used, and there are screw types such as Full Flight, Maddock and Dulmage, A full-light type is preferable for a poor cellulose acylate resin. In addition, although the equipment cost is effective, it is possible to use a twin-screw extruder capable of extruding unnecessary volatile components while installing venting holes on the way by changing the screw segment, and the twin- There is a type of incense, and both types can be used, but a type of co-rotating type in which a stay portion is hard to occur and has high self-cleaning performance is preferable. The twin-screw extruder is effective for the formation of a cellulose acetate resin because it can be extruded at a low temperature because the equipment is effective but the kneading property is high and the resin feeding performance is high. It is also possible to use the cellulose acylate pellets or the powder in an undried state as it is by appropriately arranging the venting sphere. Further, the edges of the film formed during the film-forming process can be reused as they are without being dried.

The diameter of the screw is preferably 10 mm or more and 300 mm or less, more preferably 20 mm or more and 250 mm or less, and still more preferably 30 mm or more and 150 mm or less, depending on the target extrusion amount per unit time.

(Iii) Filtration

It is preferable to carry out so-called breaker plate type filtration in which a filter element is provided at the exit of the extruder in order to filter foreign substances in the resin or to prevent damage to the gear pump by foreign matter. In addition, it is preferable to provide a filtration device equipped with a so-called leaf-type disk filter after passage of the gear pump in order to perform high-precision filtration. The filtration may be performed by providing one filtration unit, or may be multistage filtration performed by installing a plurality of filtration units. It is preferable that the filtration accuracy of the filter medium is high. However, the filtration accuracy is preferably 15 μm to 3 μm, more preferably 10 μm to 3 μm due to the internal pressure of the filter medium and the pressure increase due to clogging of the filter medium. Particularly, in the case of using a leaf-type disk filter device that performs final filtration of foreign matter, it is preferable to use a filter material having a high filtration accuracy in quality, and it is possible to adjust the number of filters to secure the suitability of internal pressure and filter life. It is preferable to use a steel material in view of the fact that the filter material is used under high temperature and high pressure. Among the steel materials, stainless steel and steel are preferably used, and stainless steel is particularly preferably used from the viewpoint of corrosion. As a constitution of the filter material, for example, a sintered filter material formed by sintering a metal long fiber or a metal powder can be used in addition to a wire material steel, and a sintered filter material is preferable from the viewpoints of filtration accuracy and filter life.

(iv) Gear pump

In order to improve the thickness accuracy, it is important to reduce variations in the amount of discharge, and it is effective to provide a gear pump between the extruder and the die and supply a certain amount of cellulose acylate resin from the gear pump. The gear pump is a structure in which a pair of gears including a drive gear and a driven gear are housed in a state where they are meshed with each other and drive the drive gear to rotate the two gears in engagement with each other so that the molten resin is sucked into the cavity from a suction port formed in the housing, A predetermined amount of the resin is discharged from a discharge port formed in the discharge port. Even if the resin pressure at the tip portion of the extruder is slightly changed, the fluctuation is absorbed by using the gear pump, and the fluctuation of the resin pressure downstream of the film-forming apparatus becomes very small. By using the gear pump, it is possible to make the fluctuation range of the resin pressure of the die portion within +/- 1%.

A method of changing the number of revolutions of the screw and controlling the pressure before the gear pump to be constant may be used in order to improve the quantitative supply performance by the gear pump. It is also effective to use a high-density gear pump using three or more gears that eliminate variations in the gears of the gear pump.

Another advantage of using a gear pump is that the pressure at the tip of the screw can be lowered to reduce the energy consumption, to prevent the resin temperature from rising, to improve the transport efficiency, to shorten the residence time in the extruder, It can be expected to shorten. In the case of using a filter for removing foreign matter, the amount of resin supplied from the screw may fluctuate with the increase of the filtration pressure without the gear pump. However, by using the gear pump in combination, it is possible to solve this problem. On the other hand, as the demerit of the gear pump, depending on the selection method of the equipment, the length of the equipment becomes long, so that the residence time of the resin becomes long and the molecular chain breaks due to the shear stress of the gear pump portion. .

The preferable residence time of the resin from the inlet to the extruder after the resin enters the extruder to the exit of the resin from the dies is from 2 to 60 minutes, more preferably from 3 to 40 minutes, more preferably from 4 to 30 minutes Or less.

Since the flow of the polymer for bearing circulation of the gear pump is deteriorated, the sealing by the polymer in the driving portion and the bearing portion becomes poor, and the fluctuation of the metering and the liquid-delivery extrusion pressure becomes large. Therefore, the melt viscosity of the cellulose acylate resin The design of the gear pump (especially the clearance) is required. Further, in some cases, the retentive portion of the gear pump causes deterioration of the cellulose acylate resin, so that a structure having as little retention as possible is preferable. In order to stabilize the extrusion pressure of the cellulose acylate resin, which is highly dependent on the temperature of the melt viscosity, it is necessary to design a polymer tube or an adapter connecting the extruder, the gear pump, It is preferable to make the fluctuation of the temperature as small as possible. Generally, a band heater with a low facility cost is often used for heating the polymer tube, but it is more preferable to use an aluminum casting heater with a smaller temperature variation. Further, in order to stabilize the discharge pressure in the extruder as described above, it is preferable to heat and melt the barrel of the extruder by a heater divided into 3 or more and 20 or less.

(v) die

The cellulose acylate resin is melted by the extruder constructed as described above, and the molten resin is continuously fed to the die via a filter and a gear pump as necessary. The die may be of any type, such as a generally used T-die or fish-tail die-coat hanger die, provided that the retention of the molten resin in the die is small. In addition, there is no problem that a static mixer for improving the uniformity of the resin temperature is placed 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 the film thickness. When the lip clearance is less than 1.0 times the film thickness, it is difficult to obtain a sheet having a good surface shape by film formation. In addition, when the lip clearance is larger than 5.0 times the film thickness, the thickness precision of the sheet is lowered, which is not preferable. The die is a very important equipment for determining the thickness accuracy of the film, and it is desirable that the thickness control can be strictly controlled. Normally, the thickness adjustment can be adjusted at an interval of 40 to 50 mm, but preferably a type capable of adjusting the film thickness at an interval of 35 mm or less, more preferably at an interval of 25 mm or less. In addition, since the cellulose acylate resin has a high temperature dependence of melt viscosity and a high shear rate dependency, it is important that the temperature deviation of the die and the fluctuation in the width direction are as small as possible. In addition, an automatic thickness adjusting die for measuring the thickness of the downstream film to calculate the thickness deviation, and feeding back the result to the thickness adjustment of the die is also effective for reducing thickness fluctuation in long-term continuous production.

(vi) Cast

In the above method, the molten resin extruded from the die into the sheet is extruded in a sheet form onto a cooling drum. At this time, the thickness deviation in the width direction can be adjusted by adjusting the intervals of the ribs of the die.

At this time, it is necessary to cool and solidify by sandwiching with a pair of metal rollers having an arithmetic mean height (Ra) of 100 nm or less and having a surface property. If a surface-quality cooling roller having an arithmetic mean height (Ra) of more than 100 nm is used, transparency of the film is lowered, which is not preferable. Preferably 50 nm or less, and more preferably 25 nm.

The cooling drum is preferably 60 ° C or more and 160 ° C or less, more preferably 70 ° C or more and 150 ° C or less, further preferably 80 ° C or more and 140 ° C or less. Thereafter, the sheet is taken out from the cooling drum, passed through a nip roller, and wound. The winding speed is preferably 10 m / min to 100 m / min, more preferably 15 m / min to 80 m / min, further preferably 20 m / min to 70 m / min.

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

When a so-called touch roller system is used, the surface of the touch roll may be made of a resin such as rubber or Teflon (registered trademark), or may be a metal roll. Further, by thinning the thickness of the metal roll, the surface of the roll slightly enters due to the pressure at the time of touch, and the area of the pressed area is widened, so that it is also possible to use a roll called a flexible roll.

The touch roll temperature is preferably from 60 캜 to 160 캜, more preferably from 70 캜 to 150 캜, further preferably from 80 캜 to 140 캜.

(vii) Coiling

The sheet thus obtained is preferably trimmed at both ends and wound. The trimmed part may be pulverized or, if necessary, subjected to a treatment such as a granulation treatment or a depolymerization / re-polymerization, and then reused as a raw material for a film of the same variety or as a raw material for a film of another kind. The trimming cutter may be any type such as a rotary cutter, a shear blade, and a knife. The material may be carbon steel or stainless steel. Generally, it is preferable to use a hard blade or a ceramic blade because the life of the cutting tool is long and the occurrence of cutting dust can be suppressed.

It is also preferable to attach the lamination film to at least one surface before winding, from the viewpoint of preventing scratches. The preferable winding tension is not less than 1 kg / m width and not more than 50 kg / width, more preferably not less than 2 kg / m width and not more than 40 kg / width, further preferably not less than 3 kg / m width and not more than 20 kg / width. When the winding tension is smaller than 1 kg / m width, it is difficult to uniformly wind the film. On the contrary, when the coiling tension is more than 50 kg / width, the film is worn by the cloth, resulting in deterioration of the appearance of the wound windup. In addition, the ridged portion of the film is stretched by the creep phenomenon to cause waving of the film, The residual birefringence due to the birefringence is undesirable. The winding tension is preferably detected by tension control during the line, and is preferably controlled while being controlled to have a certain winding tension. When there is a difference in the film temperature depending on the position of the film formation line, the length of the film may be slightly different due to thermal expansion. Therefore, the draw ratio between the nip rolls is adjusted so as not to apply a predetermined tension to the film It is necessary.

Although the winding tension can be wound by a certain tension by the control of the tension control, it is more preferable to make a taper according to the winding diameter to have a proper winding tension. Generally, the tension is slightly decreased as the winding diameter increases, but in some cases, it is preferable that the tension is increased as the bobbin diameter increases.

(Ⅷ) Properties of unstretched cellulose acylate film

The undrawn cellulose acylate film thus obtained preferably has Re = 0 to 20 nm and Rth = 0 to 20 nm when the longitudinal direction of the film is the slow axis. Re and Rth represent the in-plane retardation and the retardation in the thickness direction, respectively. Re was measured by making light incident on the KOBRA 21ADH (manufactured by Oji Scientific Co., Ltd.) in the film normal direction. Rth represents the above-mentioned Re, and Rt measured from the total of three directions of retardation measured by inclining the light axis from +40 DEG and -40 DEG inclined with respect to the normal direction of the film with the inclined axis (rotation axis) Is calculated on the basis of the value. Further, the closer to 0 deg., +90 deg. Or -90 deg., The angle formed by the film formation direction (longitudinal direction) and the slow axis of Re of the film is preferable.

The total light transmittance is preferably 90% to 100%, more preferably 91% to 99%, and still more preferably 92% to 98%. The haze is preferably 0 to 1%, more preferably 0 to 0.8%, and still more preferably 0 to 0.6%.

The thickness deviation is preferably 0% or more and 4% or less, more preferably 0% or more and 3% or less, and still more preferably 0% or more and 2% or less.

The tensile modulus of elasticity is preferably 1.5 kN / mm 2 to 3.5 kN / mm 2, more preferably 1.7 kN / mm 2 to 2.8 kN / mm 2, further preferably 1.8 kN / mm 2 to 2.6 kN / mm 2.

The elongation at break is preferably 3% or more and 100% or less, more preferably 5% or more and 80% or less, and still more preferably 8% or more and 50% or less.

The Tg (indicating the Tg of the film, that is, the cellulose acylate and the Tg of the additive mixture) is preferably 95 to 145 ° C, more preferably 100 to 140 ° C, and even more preferably 105 to 135 ° C .

The thermal dimensional change at 80 占 폚 1 day is preferably 0% or more and ± 1% or less, more preferably 0% or more ± 0.5% or less, and still more preferably 0% or more ± 0.3% or less in both longitudinal and transverse directions .

The water permeability at 40 占 폚 and 90% rh is preferably 300 g / m2 占 day to 1000 g / m2 占 day, more preferably 400 g / m2 占 day to 900 g / m2 占 day, still more preferably 500 g / m2 占Day to 800 g / m 2 · day or less.

The equilibrium moisture content at 25 캜 and 80% rh is preferably 1 wt% or more and 4 wt% or less, more preferably 1.2 wt% or more and 3 wt% or less, and further preferably 1.5 wt% or more and 2.5 wt% or less.

(8) Stretching

The film formed by the above method may be stretched. Thus, Re and Rth can be controlled.

The stretching is preferably performed at Tg + 50 deg. C or lower, more preferably Tg + 3 deg. C or higher and Tg + 30 deg. C or lower, more preferably Tg + 5 deg. C or higher and Tg + 20 deg. The preferable stretching ratio is at least 1% to 300%, more preferably 2% to 250%, and still more preferably 3% to 200%. Although it may be stretched in the longitudinal and transverse directions, it is more preferable that the stretching magnification ratio on one side is made larger than that on the other side, and the stretching is performed unevenly. The lengthwise direction (MD) and the widthwise direction (TD) may be either larger, but the smaller one is preferably 1% or more and 30% or less, more preferably 2% or more and 25% or less, Or more and 20% or less. The draw ratio of the larger one is from 30% to 300%, more preferably from 35% to 200%, further preferably from 40% to 150%. These stretching may be performed in one stage or in multiple stages. The stretching magnification referred to herein is obtained by using the following formula.

(%) = 100 x (length after stretching) - (length before stretching)} / (length before stretching)

Such stretching may be performed in two or more pairs of nip rolls at a faster peripheral speed on the exit side (lengthwise stretching), and both ends of the film are held by chucking and stretched in the orthogonal direction (direction perpendicular to the longitudinal direction) (Transverse stretching). The simultaneous biaxial stretching method disclosed in Japanese Patent Application Laid-Open Nos. 2000-37772, 2001-113591 and 2002-103445 may be used.

In order to freely control the ratio of Re and Rth, it is also possible to control the value obtained by dividing the nip roll gap by the film width (aspect ratio) in the case of longitudinal draw. That is, the Rth / Re ratio can be increased by reducing the aspect ratio. It is also possible to control Re and Rth by combining longitudinal stretching and transverse stretching. That is, Re can be made small by making the difference between the longitudinal stretching magnification and the lateral stretching magnification small, and Re can be made large by increasing this difference.

The Re and Rth of the cellulose acylate film thus stretched preferably satisfy the following formula.

Rth? Re

500 ≥ Re ≥ 0

500 ≥ Rth ≥ 30

More preferably,

Rth? Re? 1.1

150 ≥ Re ≥ 10

400 ≥ Rth ≥ 50

More preferably,

Rth? Re? 1.2

100 ≥ Re ≥ 20

350 ≥ Rth ≥ 80

Further, the closer to 0 deg., +90 deg. Or -90 deg., The angle formed by the film formation direction (longitudinal direction) and the slow axis of Re of the film is preferable. That is, in the case of the longitudinal elongation, the closer to 0 °, the more desirable is 0 ± 3 °, more preferably 0 ± 2 °, and more preferably 0 ± 1 °. In the case of transverse stretching, 90 ± 3 ° or -90 ± 3 ° is preferable, more preferably 90 ± 2 ° or -90 ± 2 °, further preferably 90 ± 1 ° or -90 ± 1 °.

The thickness variation of the cellulose acylate film after stretching is preferably 0% or more and 3% or less, more preferably 0% or more and 2% or less, and still more preferably 0% or more and 1% or less.

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

The tensile elastic modulus is preferably 1.5 kN / mm 2 to 3.0 kN / mm 2, more preferably 1.7 kN / mm 2 to 2.8 kN / mm 2, further preferably 1.8 kN / mm 2 to 2.6 kN / mm 2.

The elongation at break is preferably 3% or more and 100% or less, more preferably 5% or more and 80% or less, and still more preferably 8% or more and 50% or less.

The Tg (indicating the Tg of the film, that is, the cellulose acylate and the Tg of the additive mixture) is preferably 95 캜 to 145 캜, more preferably 100 캜 to 140 캜, and further preferably 105 캜 to 135 캜 .

The thermal dimensional change at 80 占 폚 1 day is preferably 0% or more and ± 1% or less, more preferably 0% or more ± 0.5% or less, and still more preferably 0% or more ± 0.3% or less in both longitudinal and transverse directions .

The water permeability at 40 占 폚 and 90% is preferably 300 g / m2 占 day to 1000 g / m2 占 day, more preferably 400 g / m2 占 day to 900 g / m2 占 day, still more preferably 500 g / m2 占 day Or more and 800 g / m &lt; 2 &gt;

The equilibrium moisture content at 25 캜 and 80% rh is preferably 1 wt% or more and 4 wt% or less, more preferably 1.2 wt% or more and 3 wt% or less, and further preferably 1.5 wt% or more and 2.5 wt% or less.

The thickness is preferably 30 占 퐉 or more and 200 占 퐉 or less, more preferably 40 占 퐉 to 180 占 퐉, and still more preferably 50 占 퐉 to 150 占 퐉.

The haze is 0% or more and 2.0% or less, more preferably 0% or more and 1.5% or less, further preferably 0% or more and 1% or less.

The total light transmittance is preferably 90% or more and 100% or less, more preferably 91% or more and 99% or less, and still more preferably 92% or more and 98% or less.

(9) Surface treatment

An unstretched, stretched cellulose acylate film can be improved in adhesion with each functional layer (for example, an undercoat layer and a white layer) by performing a surface treatment. For example, a glow discharge treatment, an ultraviolet ray irradiation treatment, a corona treatment, a flame treatment, an acid or an alkali treatment may be used. The above-mentioned glow discharge treatment may be a low-temperature plasma occurring under a low-pressure gas of 10 ^{-3 to 20} Torr, or plasma treatment under atmospheric pressure. Plasma-excited gas means a plasma-excited gas under the above-described conditions, and examples thereof include argon, helium, neon, krypton, xenon, nitrogen, carbon dioxide, fluorine such as tetrafluoromethane and mixtures thereof. Details of these are described in detail in pages 30 to 32 of the Inventors Association Open Publication (Air No 2001-1745, published on Mar. 15, 2001 by the Invention Society). Further, in the plasma treatment at the atmospheric pressure, which has recently attracted attention, irradiation energy of 20 to 500 Kgy is used under 10 to 1000 Kev, more preferably irradiation energy of 20 to 300 Kgy is used under 30 to 500 Kev. Of these, alkaline saponification treatment is particularly preferable, and it is very effective as a surface treatment of a cellulose acylate film. Specifically, JP-A Nos. 2003-3266, 2003-229299, 2004-322928, 2005-76088 and the like can be used.

The alkali saponification treatment may be carried out in a saponifying solution or a saponifying solution. In the case of the dipping method, an aqueous solution having a pH of 10 to 14 such as NaOH or KOH may be passed through a tank heated to 20 to 80 ° C for 0.1 to 10 minutes, followed by neutralization, washing 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 alkaline saponification treatment coating liquid is selected so as to be good in wettability because it is applied to the transparent support of the saponification liquid and to keep the surface shape in a good state without forming irregularities on the surface of the transparent support by the saponifying liquid solvent . Specifically, an alcohol-based solvent is preferable, and isopropyl alcohol is particularly preferable. An aqueous solution of a surfactant may also be used as a solvent. The alkali of the alkali saponified coating liquid is preferably alkali soluble in the above-mentioned solvent, more preferably KOH and NaOH. The pH of the saponifying coating liquid is preferably 10 or more, more preferably 12 or more. The reaction conditions at the time of alkali saponification are preferably from room temperature to 1 minute to 5 minutes, more preferably from 5 seconds to 5 minutes, and particularly preferably from 20 seconds to 3 minutes. After the alkali saponification reaction, it is preferable to wash the saponified solution-applied surface with water or acid and then with water. Further, the coating type saponification treatment and the orientation film described later can be continuously performed, and the number of processes can be reduced. Specific examples of the saponification method include those disclosed in Japanese Patent Application Laid-Open No. 2002-82226 and WO02 / 46809.

It is also preferable to form an undercoat layer for adhesion to the functional layer. This layer may be applied after the surface treatment, or may be applied without surface treatment. Details of the undercoat layer are described on page 32 of the Inventors Association's public disclosure (Air No 2001-1745, published on Mar. 15, 2001, Inventions Society).

These surface treatment and undercoating steps may be put at the end of the film forming step or may be carried out alone or in the functional layer imparting step described later.

(10) Assignment of functional layer

In the stretched and unstretched cellulose acylate films of the present invention, the functional layers described in detail in pages 32 to 45 of the Inventors' Association publication no. (Air No 2001-1745, published on Mar. 15, 2001, . Among them, preferred is the impartation of the polarizing layer (polarizing plate), the provision of the optical compensation layer (optical compensation film), the application of the antireflection layer (antireflection film), and the application of the hard coat layer.

(I) Assignment of Polarizing Layer (Production of Polarizing Plate)

[Material used for polarizing layer]

At present, commercially available polarizing layers are generally produced by immersing the stretched polymer in a solution of iodine or a dichroic dye in a bath, and infiltrating iodine or a dichroic dye into the binder. As the polarizing film, a coating type polarizing film represented by Optiva Inc. may also be used. The iodine and the dichroic dye in the polarizing film exhibit deflection performance by being oriented in the binder. As the dichroic dye, an azo dye, a stilbene dye, a parazolone dye, a triphenylmethane dye, a quinoline dye, an oxazine dye, a thiazine dye or an anthraquinone dye are used. The dichroic dye is preferably water-soluble. The dichroic dye preferably has a hydrophilic substituent (e.g., sulfo, amino, hydroxyl). For example, those disclosed in the Inventors Association Open Publication, Air No 2001-1745, page 58 (published March 15, 2001).

As the binder of the polarizing film, any of a crosslinkable polymer itself or a polymer crosslinked by a crosslinking agent may be used, and a plurality of these combinations may be used. Examples of the binder include a methacrylate copolymer, a styrenic copolymer, a polyolefin, a polyvinyl alcohol and a modified polyvinyl alcohol, a poly (N (meth) acrylate) copolymer described in Paragraph Nos. 8-338913 -Methylol acrylamide), polyester, polyimide, vinyl acetate copolymer, carboxymethylcellulose, polycarbonate and the like. A silane coupling agent may be used as the polymer. Gelatin, polyvinyl alcohol and modified polyvinyl alcohol are more preferable, and poly (vinyl alcohol) and poly (vinyl alcohol) are more preferable, Most preferred are vinyl alcohol and modified polyvinyl alcohol. It is particularly preferable to use two types of polyvinyl alcohol or modified polyvinyl alcohol having different degrees of polymerization in combination. The saponification degree of polyvinyl alcohol is preferably 70 to 100%, more preferably 80 to 100%. The degree of polymerization of polyvinyl alcohol is preferably 100 to 5000. Modified polyvinyl alcohols are described in JP-A-8-338913, JP-A-9-152509 and JP-A-9-316127. The polyvinyl alcohol and the modified polyvinyl alcohol may be used in combination of two or more kinds.

The lower limit of the thickness of the binder is preferably 10 mu m. From the viewpoint of light leakage of the liquid crystal display device, the upper limit of the thickness is preferably as thin as possible. (About 30 mu m) or less, preferably 25 mu m or less, and more preferably 20 mu m or less.

The binder of the polarizing film may be crosslinked. A polymer or monomer having a crosslinkable functional group may be mixed in the binder, or a crosslinkable functional group may be added to the binder polymer itself. The crosslinking can be carried out by light, heat or pH change, and a binder having a crosslinking structure can be formed. As for the crosslinking agent, it is described in the specification of US Reissue Patent No. 23297. Boron compounds (e.g., boric acid, borax) can also be used as the crosslinking agent. The amount of the crosslinking agent to be added to the binder is preferably from 0.1 to 20 mass% with respect to the binder. The orientation properties of the polarizing element and the humidity and humidity resistance of the polarizing film become good.

Even after the completion of the crosslinking reaction, the amount of the unreacted crosslinking agent is preferably 1.0 mass% or less, more preferably 0.5 mass% or less. By doing so, the weather resistance is improved.

[Stretching of polarizing film]

The polarizing film is preferably dyed with iodine or a dichroic dye after stretching the polarizing film (stretching method) or rubbing (rubbing method).

In the case of the stretching method, the draw ratio is preferably 2.5 to 30.0 times, more preferably 3.0 to 10.0 times. The stretching can be performed by dry stretching in air. Further, wet stretching in a state of being immersed in water may be performed. The stretching magnification of the dry stretching is preferably 2.5 to 5.0 times, and the stretching magnification of the wet stretching is preferably 3.0 to 10.0 times. The stretching may be performed in parallel in the MD direction (parallel stretching) or in an oblique direction (oblique stretching). These stretching may be performed in one cycle or in several cycles. The stretching can be performed more uniformly even at high magnification elongation by dividing by a number of circuits. More preferably, it is an oblique stretching method in which an oblique stretch is applied at an angle of 10 to 80 degrees in an oblique direction.

(I) parallel stretching method

Prior to stretching, the PVA film is swollen. The degree of swelling is 1.2 to 2.0 times (mass ratio before swelling and after swelling). Thereafter, the film is stretched in a bath of 15 to 50 DEG C, preferably 17 to 40 DEG C in a dyeing bath for dissolving dichroic substances in an aqueous medium bath and continuous feeding through a guide roll or the like. The stretching can be achieved by grasping with two pairs of nip rolls and increasing the conveying speed of the nip roll at the rear end to be higher than the conveying speed at the front end. The stretching magnification is based on the ratio of the length after stretching to the initial state (hereinafter the same), but the stretching magnification is preferably 1.2 to 3.5 times, and more preferably 1.5 to 3.0 times from the viewpoint of the above effect. Thereafter, it is dried at 50 ° C to 90 ° C to obtain a polarizing film.

(II) oblique stretching method

A method of stretching using a tenter projecting in an oblique direction as described in JP-A-2002-86554 can be used. Since this stretching is performed in the air, it is necessary to function beforehand to make it easy to stretch. The preferable water content is 5% or more and 100% or less. The stretching temperature is preferably 40 占 폚 or more and 90 占 폚 or less, and the humidity during stretching is preferably 50% rh or more and 100% rh or less.

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

[join]

The saponified stretched, unstretched cellulose acylate film and a polarizing layer prepared by stretching are bonded to each other to prepare a polarizing plate. The bonding direction is not particularly limited, but it is preferable that the direction of the flexible axis of the cellulose acylate film and the stretching axis direction of the polarizing plate are any one of 0 degree, 45 degrees, and 90 degrees.

The adhesive for bonding is not particularly limited, but PVA resin (including modified PVA such as acetoacetyl group, sulfonic acid group, carboxyl group and oxyalkylene group) and aqueous solution of boron compound and the like can be mentioned. Among them, PVA resin desirable. The thickness of the adhesive layer is preferably 0.01 to 10 mu m after drying, and particularly preferably 0.05 to 5 mu m.

As the layer structure of the bonding, the following can be mentioned.

(a) A / P / A

(b) A / P / B

(c) A / P / T

(d) B / P / B

(e) B / P / T

A is an undrawn film of the present invention, B is a stretched film of the present invention, T is a cellulose triacetate film (Fuji Photo Film), and P is a polarizing layer. In the case of the constitutions (a) and (b), A and B may be cellulose acetate having the same composition or different ones. (d), B may be cellulose acetate having the same composition, different cellulose acylate, or different stretching magnification with or without the same stretching magnification. Further, in the case of using in the liquid crystal display device, either of them may be used as the liquid crystal surface, and in the case of the constitutions (b) and (e), B is more preferably set to the liquid crystal side.

(A) to (e) of the present invention and a conventional polarizing plate (T / P / T) can be freely combined with each other in the liquid crystal display device . However, it is preferable that a transparent hard coat layer, an antiglare layer, an antireflection layer, and the like are formed on the outermost film on the display side of the liquid crystal display device, and those described later can be used.

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

Further, the polarizing plate thus obtained can be laminated with a? / 4 plate to produce circularly polarized light. In this case, the slow axis of? / 4 and the absorption axis of the polarizing plate are laminated at 45 degrees. In this case,? / 4 is not particularly limited, but more preferably, it is more preferable that the wavelength dependence is such that the lower the wavelength, the smaller the retardation. It is also preferable to use a? / 4 plate composed of a polarizing film having an absorption axis oriented at 20 to 70 degrees in the longitudinal direction and an optically anisotropic layer made of a liquid crystalline compound.

A protective film may be bonded to one side of these polarizing plates and a separate film may be bonded to the opposite side. The protective film and the separate film are used for the purpose of protecting the polarizing plate when the polarizing plate is shipped, when the product is inspected, and the like.

(Ii) Preparation of Optical Compensation Layer (Preparation 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 is formed by forming an orientation film on the stretched, unstretched cellulose acylate film, and further providing an optically anisotropic layer.

[Alignment film]

An orientation film is formed on the surface-treated, drawn and unstretched cellulose acylate film. This film has a function of defining the alignment direction of liquid crystal molecules. However, if the orientation state of the liquid crystalline compound is fixed after orientation, the orientation film is not necessarily essential as a constituent element of the present invention because it is doing its part. That is, only the optically anisotropic layer on the alignment film on which the alignment state is fixed, can be transferred onto the polarizer to produce the polarizing plate of the present invention.

The orientation film may be formed by rubbing an organic compound (preferably a polymer), forming a layer having a microgroove, or forming a layer having an organic compound (e.g., an organic compound) by a Langmuir-Blodgett method (LB film) omega -tricoic acid, dioctadecylmethylammonium chloride, methyl stearate), and the like. Also known is an orientation film in which an orientation function is generated by application of an electric field, application of a magnetic field, or light irradiation.

The alignment film is preferably formed by rubbing the polymer. The polymer used in the alignment layer has a molecular structure that has a function of orienting liquid crystal molecules in principle.

In the present invention, in addition to the function of orienting liquid crystal molecules, a side chain having a crosslinkable functional group (e.g., a double bond) is bonded to a main chain, or a crosslinkable functional group having a function of orienting liquid crystalline molecules is introduced .

As the polymer used for the alignment film, any of a polymer that is itself crosslinkable or a polymer that is crosslinked by a crosslinking agent may be used, and a plurality of these may be used in combination. Examples of the polymer include a methacrylate-based copolymer, a styrene-based copolymer, a polyolefin, a polyvinyl alcohol and a modified polyvinyl alcohol, poly (N-methylol acrylamide), polyester, polyimide, vinyl acetate copolymer, carboxymethylcellulose, polycarbonate and the like. A silane coupling agent may be used as the polymer. Gelatin, polyvinyl alcohol and modified polyvinyl alcohol are more preferable, and poly (vinyl alcohol) and poly (vinyl alcohol) are more preferable, Most preferred are vinyl alcohol and modified polyvinyl alcohol. It is particularly preferable to use two types of polyvinyl alcohol or modified polyvinyl alcohol having different degrees of polymerization in combination. The saponification degree of polyvinyl alcohol is preferably 70 to 100%, more preferably 80 to 100%. The degree of polymerization of polyvinyl alcohol is preferably 100 to 5000.

The side chain having the function of orienting liquid crystalline molecules generally has a hydrophobic group as a functional group. The type of the specific functional group is determined depending on the kind of the liquid crystalline molecule and the required orientation state. For example, the modified polyvinyl alcohol can be introduced by copolymerization denaturation, chain transfer denaturation, or block polymerization denaturation. Examples of the substituent include a hydrophilic group (such as a carboxylic acid group, a sulfonic acid group, a phosphonic acid group, an amino group, an ammonium group, an amide group or a thiol group), a hydrocarbon group of 10 to 100 carbon atoms, a fluorine atom-substituted hydrocarbon group, An alkoxysilyl group (trialkoxy, dialkoxy, monoalkoxy), and the like can be given. As specific examples of these modified polyvinyl alcohol compounds, for example, Japanese Patent Application Laid-Open No. 2000-155216, paragraphs [0022] to [0145], paragraphs [0018] to [ 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 the side chain having a function of aligning the liquid crystal molecules, the polymer of the alignment film and the polyfunctional monomer contained in the optically anisotropic layer are copolymerized . As a result, not only between the multifunctional monomer and the multifunctional monomer but also between the alignment film polymer and the alignment film polymer, and between the multifunctional monomer and the alignment film polymer are 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 orientation film polymer preferably contains a polymerizable group as in the case of the polyfunctional monomer. Specific examples thereof include those described in paragraphs [0080] to [0100] in the specification of Japanese Patent Application Laid-Open No. 2000-155216. The orientation film polymer may be crosslinked using a crosslinking agent separately from the above-mentioned crosslinkable functional group.

Examples of the crosslinking agent include aldehydes, N-methylol compounds, dioxane derivatives, compounds which act by activating carboxyl groups, active vinyl compounds, active halogen compounds, isoxazole and dialdehyde starches. Two or more kinds of crosslinking agents may be used in combination. Specific examples thereof include compounds described in paragraphs [0023] to [024] in the specification of Japanese Patent Application Laid-Open No. 2002-62426. Highly reactive aldehydes, especially glutaraldehyde, are preferred.

The addition amount of the crosslinking agent is preferably from 0.1 to 20 mass%, more preferably from 0.5 to 15 mass%, based on the polymer. The amount of the unreacted crosslinking agent remaining in the alignment film is preferably 1.0 mass% or less, more preferably 0.5 mass% or less. With this adjustment, sufficient durability without reticle occurrence can be obtained even if the alignment film is left in a liquid crystal display for a long time or under a high temperature and high humidity atmosphere for a long time.

The alignment film can be formed by applying it on a transparent support containing the polymer and the crosslinking agent, which is basically an alignment film forming material, followed by heating and drying (crosslinking) and rubbing treatment. The crosslinking reaction may be carried out at an arbitrary timing after coating on the transparent support as described above. When a water-soluble polymer such as polyvinyl alcohol is used as an alignment film-forming material, it is preferable that the coating liquid is a mixed solvent of an organic solvent having an antifoaming action (e.g., methanol) and water. The ratio of water to methanol is preferably 0: 100 to 99: 1, more preferably 0: 100 to 91: 9 in terms of a mass ratio. As a result, the generation of bubbles is suppressed, and defects on the surface of the alignment layer and the layer of the optically anisotropic layer are remarkably reduced.

The coating method of the orientation film is preferably a spin coating method, a dip coating method, a curtain coating method, an extrusion coating method, a rod coating method or a roll coating method. The rod coating method is particularly preferable. The film thickness after drying is preferably 0.1 to 10 mu m. The heating and drying can be carried out at 20 캜 to 110 캜. In order to form sufficient crosslinking, the temperature is preferably 60 ° C to 100 ° C, more preferably 80 ° C to 100 ° C. The drying time can be from 1 minute to 36 hours, preferably from 1 minute to 30 minutes. The pH is preferably set to an optimum value for the crosslinking agent to be used. When glutaraldehyde is used, the pH is preferably 4.5 to 5.5, and particularly preferably 5.

An orientation film is formed on the stretched and unstretched cellulose acylate film or on the undercoat layer. The orientation film can be obtained by crosslinking the polymer layer as described above and then rubbing the surface.

As the rubbing treatment, a widely employed treatment method can be applied as a liquid crystal alignment treatment process of an LCD. That is, a method of obtaining orientation by rubbing the surface of the alignment film in a predetermined direction using paper, gauze, felt, rubber, nylon, polyester fiber or the like can be used. Generally, this is carried out by rubbing the fabric several times with a cloth or the like on which an average fiber of uniform length and thickness is formed.

When the film is industrially carried out, it is achieved by bringing a rotating rubbing roll into contact with the film having the polarizing layer being conveyed, but it is preferable that the roundness, the cylindricality and the shaking (eccentricity) of the rubbing roll are all 30 m or less. The wrap angle of the film of the rubbing roll is preferably 0.1 to 90 deg. However, as described in JP-A-8-160430, a stable rubbing treatment can be obtained by winding at least 360 degrees. The transporting speed of the film is preferably 1 to 100 m / min. It is preferable to select an appropriate rubbing angle in the range of 0 to 60 degrees. And when it is used in a liquid crystal display device, it is preferably 40 to 50 degrees. 45 DEG is particularly preferable.

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

Next, the liquid crystalline molecules of the optically anisotropic layer are oriented on the alignment film. Thereafter, the orientation film polymer is crosslinked with a multifunctional monomer contained in the optically anisotropic layer, or with a crosslinking agent, if necessary.

The liquid crystal molecules used in the optically anisotropic layer include rod-shaped liquid crystal molecules and disc-shaped liquid crystal molecules. The rod-like liquid crystal molecules and the disc-shaped liquid crystal molecules may be either polymer liquid crystals or low molecular liquid crystals, and those in which the low molecular weight liquid crystals are not crosslinked to exhibit liquid crystallinity.

[Rod-shaped liquid crystalline molecule]

Examples of rod-shaped liquid crystalline molecules include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano- Alkoxy-substituted phenylpyrimidines, phenyl dioxanes, tolans, and alkenylcyclohexyl benzonitriles are preferably used.

The rod-shaped liquid crystalline molecules also contain metal complexes. The liquid crystal polymer containing rod-shaped liquid crystal molecules in the repeating unit can also be used as the rod-like liquid crystal molecules. In other words, the rod-shaped liquid crystalline molecules may be bonded to the (liquid crystal) polymer.

For rod-shaped liquid crystalline molecules, refer to Chapter 3 of the Journal of the Chemical Society of Japan (1994), Chemistry of Liquid Crystals (1994), Chapter 4, Chapter 7 and Chapter 11, .

The birefringence of the stick-shaped liquid crystalline molecules is preferably in the range of 0.001 to 0.7.

It is preferable that the rod-like liquid crystalline molecules have a polymerizable group in order to fix the alignment state thereof. The polymerizable group is preferably a radical polymerizable imbibition group or a cationic polymerizable group, and specifically includes, for example, a polymerizable group described in paragraphs [0064] to [0086] in JP-A No. 2002-62427 Liquid crystal compounds.

[Disk-shaped liquid crystalline molecule]

Discotic liquid crystals have been studied in C.Destrade, Mol. Cryst. 71, 111 (1981), a report of a study of benzene derivatives and C.Destrades, Mol. Cryst. 122, 141 (1985), Physics Lett, A, 78, 82 (1990). Chem. 96, 70 (1984), J. Chem. Lehn, J. Chem. Commun., 1794 (1985), J. Zhang et al., J. Am. Chem. Soc. 116, 2655 (1994), and the phenacetylenic macrocycles.

Examples of the discotic liquid crystalline molecules include liquid crystalline compounds in which linear alkyl groups, alkoxy groups, and substituted benzoyloxy groups are substituted with the side chain of the mother nucleus in the radial form with respect to the parent nucleus of the center of the molecule. It is preferable that the molecules or aggregates of molecules have rotational symmetry and can give a constant orientation. The optically anisotropic layer formed from the discotic liquid crystalline molecules does not need to be the discotic liquid crystalline molecule finally contained in the optically anisotropic layer. For example, when the discotic liquid crystalline molecule is reacted by heat or light , And as a result, a compound which polymerizes or crosslinks by reaction with heat or light to form a high molecular weight and loses liquid crystallinity is included. A preferable example of the discotic liquid crystalline molecules is 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 discotic liquid crystalline molecules. The discotic core and the polymerizable group are preferably a compound that bonds through a linking group, and thus the orientation state can be maintained in the polymerization reaction. For example, compounds described in paragraphs [0151] to [0168] in the specification of Japanese Patent Application Laid-Open No. 2000-155216.

In the hybrid alignment, the angle between the major axis (circular one) of the discotic liquid crystalline molecule and the plane of the polarizing film is the depth direction of the optically anisotropic layer and increases or decreases with increasing distance from the plane of the polarizing film. It is desirable that the angle decreases with increasing distance. In addition, changes in the angle include continuous increase, continuous decrease, intermittent increase, intermittent decrease, change including continuous increase and continuous decrease, or intermittent change including increase and decrease. The intermittent change includes an area where the inclination angle does not change in the course of the thickness direction. The angle may include an area where the angle is not changed, but it may be increased or decreased as a whole. It is also preferable that the angle is continuously changed.

The average direction of the long axes of the discotic liquid crystalline molecules on the side of the polarizing film can generally be adjusted by selecting materials of discotic liquid crystalline molecules or orientation films or by selecting a rubbing treatment method. In addition, the long axis (circular direction) direction of the discotic liquid crystalline molecules on the front side (air side) can generally be adjusted by selecting the kind of additive to be used together with the discotic liquid crystalline molecules or the discotic liquid crystalline molecules. Examples of the additive to be used together with the discotic liquid crystalline molecules include a plasticizer, a surfactant, a polymerizable monomer and a polymer. The degree of change in the long axis alignment direction can also be adjusted by selecting the liquid crystal molecules and additives as described above.

&Quot; Other compositions of optically anisotropic layer &quot;

A plasticizer, a surfactant, a polymerizable monomer and the like may be used together with the liquid crystal molecule to improve the uniformity of the coating film, the strength of the film, and the orientation of the liquid crystal molecules. It is preferable that it has compatibility with the liquid crystal molecules and does not change the inclination angle of the liquid crystal molecules or does not inhibit the orientation.

Examples of the polymerizable monomer include radical polymerizable or cationic polymerizable compounds. Preferably a multifunctional radically polymerizable monomer, and is preferably copolymerized with the liquid crystal compound containing the polymerizable group. For example, those described in paragraphs [0018] to [0020] in the specification of Japanese Patent Application Laid-Open No. 2002-296423. The amount of the compound added is generally in the range of 1 to 50 mass%, preferably 5 to 30 mass%, based on the discotic liquid crystalline molecule.

As the surfactant, conventionally known compounds may be mentioned, but a fluorine-based compound is particularly preferable. Specifically, for example, compounds described in paragraphs [0028] to [0056] in the specification of Japanese Patent Application Laid-Open No. 2001-330725 can be mentioned.

The polymer used together with the discotic liquid crystalline molecules is preferably capable of imparting a change in the inclination angle to the discotic liquid crystalline molecules.

An example of the polymer is a cellulose ester. Preferable examples of the cellulose ester include those described in paragraph [0178] in the specification of Japanese Patent Application Laid-Open No. 2000-155216. The addition amount of the polymer is preferably in the range of 0.1 to 10 mass%, and more preferably in the range of 0.1 to 8 mass% with respect to the liquid crystal molecules so as not to hinder the orientation of the liquid crystal molecules.

The discotic nematic liquid phase-solid phase transition temperature of discotic liquid crystalline molecules is preferably 70 to 300 占 폚, more preferably 70 to 170 占 폚.

[Formation of optically anisotropic layer]

The optically anisotropic layer can be formed by applying a liquid crystal molecule and, if necessary, a coating liquid containing a polymerizable initiator and an arbitrary component described below on an alignment film.

As the solvent used for preparing the coating liquid, an organic solvent is preferably used. Examples of the organic solvent include amides such as N, N-dimethylformamide, sulfoxides such as dimethylsulfoxide, heterocyclic compounds such as pyridine, hydrocarbons such as benzene and hexane, (For example, acetone, methyl ethyl ketone), an ether (for example, tetrahydrofuran, 1,2-dimethoxyethane), or an organic solvent such as tetrahydrofuran, . Alkyl halides and ketones are preferred. Two or more kinds of organic solvents may be used in combination.

The coating liquid may be applied by a known method (e.g., a wire bar coating method, an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, a die coating method).

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

[Fixation of alignment state of liquid crystal molecules]

The aligned liquid crystal molecules can be held in the aligned state and fixed. The immobilization is preferably carried out 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 preferable.

Examples of the photopolymerization initiator include α-carbonyl compounds (described in each specification of US Pat. Nos. 2367661 and 2367670), acyloin ethers (described in US Patent 2448828), α-hydrocarbon substituted aromatic acyloin compounds 2722512), a polynuclear quinone compound (described in U.S. Patent Nos. 3046127 and 2951758), a combination of triarylimidazole dimer and p-aminophenyl ketone (described in U.S. Patent No. 3549367), acridine and Phenazine compounds (JP 60-105667 A, JP 4239850 B), and oxadiazole compounds (JP 4212970 B).

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

It is preferable to use ultraviolet light for light irradiation for polymerization of liquid crystal molecules.

The irradiation energy is preferably in a range of 20 mJ / cm 2 to 50 J / cm 2, more preferably in a range of 20 to 5000 mJ / cm 2, and still more preferably in a range of 100 to 800 mJ / cm 2. In order to accelerate the photopolymerization reaction, light irradiation may be carried out under heating conditions.

The protective layer may be formed on the optically anisotropic layer.

It is also preferable to combine the optical compensation film and the polarizing layer. Specifically, an optically anisotropic layer is formed by applying the coating liquid for optically anisotropic layer as described above to the surface of the polarizing film. As a result, a thin polarizing plate having a small stress (deformation x cross-sectional area x modulus of elasticity) due to dimensional changes of the polarizing film is produced without using a polymer film between the polarizing film and the optically anisotropic layer. When the polarizing plate according to the present invention is attached to a large-sized liquid crystal display device, problems such as light leakage do not occur, and an image with high display quality can be displayed.

It is preferable that the tilting angles of the polarizing layer and the optical compensating layer are elongated so as to match the angle formed by the transmission axis of the two polarizing plates bonded to both sides of the liquid crystal cell constituting the LCD and the longitudinal or transverse direction of the liquid crystal cell. The normal inclination angle is 45 degrees. However, in recent years, apparatuses that are not always 45 deg. In the transmissive, reflective, and semi-transmissive LCDs have been developed, and it is desirable that the stretching direction can be arbitrarily adjusted in accordance with the design of the LCD.

&Quot; Liquid crystal display device &quot;

Each liquid crystal mode in which such an optical compensation film is used will be described.

(TN mode liquid crystal display device)

And is most widely used as a color TFT liquid crystal display device, and is described in a large number of documents. In the alignment state in the liquid crystal cell in the black display of the TN mode, rod-like liquid crystal molecules stand up in the central portion of the cell and rod-like liquid crystal molecules are in a lying state in the vicinity of the substrate of the cell.

(OCB mode liquid crystal display device)

(Symmetrically) in a direction substantially opposite to the upper and lower portions of the liquid crystal cell. A liquid crystal display device using a liquid crystal cell of the bend alignment mode is disclosed in U.S. Patent Nos. 4583825 and 5410422, respectively. Since the rod-like liquid crystalline molecules are symmetrically oriented in the upper and lower portions of the liquid crystal cell, the liquid crystal cell of the bend alignment mode has a magneto-optical compensation function. For this reason, this liquid crystal mode is also referred to as OCB (Optically Compensatory Bend) liquid crystal mode.

In the liquid crystal cell of the OCB mode, like the TN mode, in the black display, the alignment state in the liquid crystal cell is such that rod-like liquid crystal molecules stand up in the central portion of the cell and the rod-like liquid crystal molecules are in a lying state in the vicinity of the substrate of the cell.

(VA mode liquid crystal display device)

The liquid crystal cell of the VA mode is characterized by (1) orienting the rod-like liquid crystalline molecules substantially vertically at a voltage-unapplied state, and when the voltage is applied (2) a liquid crystal cell (MVA mode) in which a VA mode is converted into a multi-domain for the purpose of enlarging the viewing angle, in addition to the narrow VA mode liquid crystal cell (3) a mode in which rod-like liquid crystal molecules are substantially vertically aligned at the time of voltage uninfluence and twisted at the time of voltage application to cause multidomain orientation (refer to SID97, Digest of Tech. Papers 28 (1997) 845) n-ASM mode liquid crystal cell of the liquid crystal cell of the SURVAIVAL mode (disclosed in LCD International 98) disclosed in Japanese Liquid Crystal Panel discussion 58-59 (1998).

(IPS mode liquid crystal display device)

Shaped liquid-crystal molecules are horizontally oriented substantially in the plane when the voltage is not applied. This characteristic is characterized in that switching is effected by changing the alignment direction of the liquid crystal depending on the presence or absence of voltage application. More specifically, Japanese Patent Application Laid-Open Nos. 2004-365941, 2004-12731, 2004-215620, 2002-221726, 2002-55341, 2003-195333 And the like can be used.

(Other liquid crystal display device)

It is possible to optically compensate for the ECB mode and the STN (Super Twisted Nematic) mode, the FLC (Ferroelectric Liquid Crystal) mode, the AFLC (Anti-ferroelectric Liquid Crystal) mode, and the ASM (Axially Symmetric Aligned Microcell) can do. It is also effective in any of liquid crystal display devices of transmission type, reflection type, and semi-transmission type. And is also advantageously used as an optical compensation sheet of a reflection-type liquid crystal display of the GH (Guest-Host) type.

The use of these detailed cellulose derivative films described above has been described in detail in pages 45 to 59 of the Inventor Association Open Publication (Air No 2001-1745, published on Mar. 15, 2001, Invention Society).

&Quot; Application of antireflection layer (antireflection film) &quot;

The antireflection film is formed by providing a low refractive index layer which is generally an antifouling layer and at least one layer having a higher refractive index than the low refractive index layer (that is, a high refractive index layer and a medium refractive index layer) on a transparent substrate.

As a multilayer film in which a transparent thin film of an inorganic compound (metal oxide or the like) having a different refractive index is laminated, a colloidal metal oxide particle film (for example, a metal oxide film or a metal oxide film) may be formed by a sol-gel method of a metal compound such as a chemical vapor deposition (CVD) method, a physical vapor deposition (Ultraviolet ray irradiation: Japanese Patent Application Laid-Open No. 9-157855, plasma treatment: Japanese Patent Application Laid-Open No. 2002-327310) to form a thin film.

On the other hand, various antireflection films obtained by laminating a thin film formed by dispersing inorganic particles in a matrix as a highly productive antireflection film have been proposed.

An antireflection film comprising an antireflection layer imparting antifogging properties to the surface of the uppermost layer having fine irregularities may be exemplified as the antireflection film by coating as described above.

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

[Layer structure of coating type antireflection film]

An antireflection film having a layer structure in order of at least a medium refractive index layer, a high refractive index layer and a low refractive index layer (outermost layer) on a substrate is designed to have a refractive index satisfying the following relationship.

The refractive index of the high refractive index layer> the refractive index of the medium refractive index layer> the refractive index of the transparent support> the refractive index of the low refractive index layer, or the hard coat layer may be formed between the transparent support and the medium refractive index layer.

Further, it may be composed of a medium refractive index hard coat layer, a high refractive index layer and a low refractive index layer.

For example, JP-A-8-122504, JP-A-8-110401, JP-A-10-300902, JP-A-2002-243906, and JP-A-2000-111706. For example, antifouling low refractive index layers and antistatic high refractive index layers (for example, JP-A-10-206603 and JP-A-2002-243906 Etc.).

The haze of the antireflection film is preferably 5% or less, more preferably 3% or less. The strength of the film is preferably H or more, more preferably 2H or more, and most preferably 3H or more in the 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 inorganic compound ultrafine particle having a high refractive index of 100 nm or less and an average particle diameter of 100 nm or less and a matrix binder.

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

In order to obtain such ultrafine particles, it is preferable that the surface of the particles is treated with a surface treatment agent (for example, a silane coupling agent, etc., JP-A Nos. 11-295503, 11-153703, 2000-9908, (Japanese Unexamined Patent Publication (Kokai) No. 2001-310432), a core shell structure having a core of high refractive index as a core (for example, Japanese Patent Application Laid-Open No. 2001-166104), a specific dispersant Japanese Patent Application Laid-Open No. 11-153703, Japanese Patent Application No. 6210858B1, Japanese Patent Application Laid-Open No. 2002-2776069, etc.).

As the material for forming the matrix, conventionally known thermoplastic resins, curable resin coatings and the like can be given.

Also preferred is a composition comprising a multifunctional compound containing at least two radically polymerizable and / or cationically polymerizable polymerizable groups, at least one composition selected from organometallic compounds containing a hydrolysable group and a partial condensate thereof . For example, compounds described in Japanese Patent Application Laid-Open Nos. 2000-47004, 2001-315242, 2001-31871, 2001-296401, and the like.

Also preferred is a curable film obtained from a colloidal metal oxide obtained from the hydrolysis condensate of a metal alkoxide and a metal alkoxide composition. For example, in Japanese Patent Laid-Open No. 2001-293818.

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

The refractive index of the medium 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 medium refractive index layer is preferably 1.50 to 1.70.

[Low Refractive Index Layer]

The low refractive index layers are sequentially laminated on the high refractive index layer. The refractive index of the low refractive index layer is 1.20 to 1.55. Preferably 1.30 to 1.50.

It is preferable to construct it as an outermost layer having scratch resistance and antifouling properties. As a means for greatly improving scratch resistance, the provision of sliding property to the surface is effective, and a means of a thin film layer comprising introduction of conventionally known silicon, introduction of fluorine, and the like can be applied.

The refractivity of the fluorinated compound is preferably 1.35 to 1.50. And more preferably from 1.36 to 1.47. The fluorinated compound is preferably a compound containing a crosslinkable or polymerizable functional group containing a fluorine atom in a range of 35 to 80 mass%.

For example, Japanese Patent Application Laid-Open No. 9-222503, paragraphs [0018] to [0026], paragraphs 11-38202, paragraphs [0019] to [0030], and Japanese Patent Application Laid-Open No. 2001-40284 [0027] to [0028], JP-A-2000-284102, and the like.

The silicone compound is preferably a compound having a polysiloxane structure and contains a curable functional group or a polymerizable functional group in the polymer chain and has a crosslinking structure in the film. Examples thereof include reactive silicones (e.g., Sylar Plain (manufactured by Thixo Corporation), polysiloxanes containing silanol groups at both ends (Japanese Patent Application Laid-Open No. 11-258403), and the like.

The crosslinking or polymerization reaction of the fluorine-containing and / or siloxane-containing polymer having a crosslinking or polymerizing group is carried out by applying a coating composition for forming an outermost layer containing a polymerization initiator, a sensitizer, etc., .

It is also preferable to use a sol-gel cured film for curing a silane coupling agent containing a specific fluorine-containing hydrocarbon group and an organometallic compound such as a silane coupling agent by a condensation reaction in the coexistence of a catalyst.

For example, a polyfluoroalkyl group-containing silane compound or its partial hydrolyzed condensate (Japanese Patent Application Laid-Open Nos. 58-142958, 58-147483, 58-147484, and 9-157582 A silyl compound containing a fluorine-containing long chain group "polyperfluoroalkyl ether" group (JP-A-2000-117902, JP-A-2001-48590, Compounds described in JP-A-2002-53804, etc.).

The low refractive index layer may contain a low refractive index inorganic compound having an average primary particle diameter of 1 to 150 nm, such as silicon dioxide (silica), fluorine particles (magnesium fluoride, calcium fluoride, barium fluoride) , Organic fine particles described in paragraphs [0020] to [0038] of JP-A 11-3820, silane coupling agents, lubricants, surfactants, and the like.

When the low refractive index layer is located in the lower layer of 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 or the like). The coating method is preferable because it can be produced at low cost.

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

[Hard coat layer]

The hard coat layer is provided on the surface of the stretched and unstretched cellulose acylate film to impart physical strength to the antireflection film. Particularly, it is preferable to be provided between the stretched and unstretched cellulose acylate film and the high refractive index layer. It is also preferable to coat the film directly on the stretched and unstretched cellulose acylate film without providing the antireflection layer.

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

Specific examples of these compounds include those exemplified in the high refractive index layer.

Specific examples of the composition of the hard coat layer include those described in Japanese Patent Application Laid-Open Nos. 2002-144913, 2000-9908, WO00 / 46617, and the like.

The high refractive index layer can also serve as a hard coat layer. In such a case, it is preferable that the fine particles are finely dispersed and contained in the hard coat layer by a method based on the high refractive index layer.

The hard coat layer may also serve as an antiglare layer (to be described later) containing particles having an average particle diameter of 0.2 to 10 mu m and imparting an antiglare function (antiglare function).

The thickness of the hard coat layer can be suitably designed in accordance with the use. The thickness of the hard coat layer is preferably 0.2 to 10 mu m, more preferably 0.5 to 7 mu m.

The strength of the hard coat layer is preferably not less than H in the pencil hardness test according to JIS K5400, more preferably not less than 2H, and most preferably not less than 3H. In addition, in the Taber test according to JIS K5400, it is preferable that the wear amount of the test piece before and after the test is small.

[Front scattering layer]

The forward scattering layer is provided to give an effect of improving the viewing angle when the viewing angle is inclined in the up, down, left, and right 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 Unexamined Patent Application Publication No. 11-38208 discloses that the forward scattering coefficient is specified, Japanese Unexamined Patent Application Publication No. 2000-199809 where the relative refractive index of the transparent resin and the fine particles is in a specific range, and haze value is defined as 40% Japanese Patent Application Laid-Open No. 2002-107512, and the like.

[Other floors]

In addition to the above layer, a primer layer, an antistatic layer, an undercoat layer or a protective layer may be formed.

[Application 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 method, a microgravure method or an extrusion coating method (US Patent No. 2681294 specification) , And can be formed by coating.

[Antiglare function]

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

Any method can be applied to the method for forming the concavo-convex on the surface of the antireflection film as long as the method can sufficiently maintain the surface shape of the antireflection film. For example, a method of forming irregularities on the surface of a film using fine particles in a low refractive index layer (for example, Japanese Unexamined Patent Application Publication No. 2000-271878), a method of forming a lower layer (a high refractive index layer, A method in which a small amount (0.1 to 50 mass%) of relatively large particles (particle size 0.05 to 2 mass%) is added to a surface layer (a coating layer) to form a surface roughened film and these shapes are maintained thereon to form a low refractive index layer Japanese Unexamined Patent Application Publication Nos. 2000-281410, 2000-95893, 2001-100004, 2001-281407, etc.), a method of physically transferring a concave-convex shape to the surface after applying the top layer (antifouling layer) (For example, Japanese Patent Application Laid-Open Nos. 63-278839, 11-183710, 2000-275401, etc.) as an embossing method.

[Usage]

The unstretched, stretched cellulose acylate film of the present invention can be used for an optical film, particularly for a polarizing plate protective film, an optical compensation sheet (also referred to as a retardation film) of a liquid crystal display device, an optical compensating sheet for a reflective liquid crystal display device, It is useful as a support.

The measuring method used in the present invention will be described below.

(1) Modulus of elasticity

The stress at 0.5% elongation was measured at a tensile rate of 10% / min in an atmosphere of 23 ° C and 70% rh to determine a modulus of elasticity. MD, and TD, and this average value is referred to as elastic modulus.

(2) Substitution degree of cellulose acylate

The degrees of substitution of the respective acyl groups of the cellulose acylate and the degree of substitution at the 6-position thereof are as shown in Carbohydr. Res. 273 (1995) 83-91 (Tezuka et al.).

(3) Residual solvent

300 mg of the sample film was dissolved in 30 ml of methyl acetate (Sample A), and 30 ml of dichloromethane (Sample B) was prepared.

These were measured by gas chromatography (GC) under the following conditions.

Column: DB-WAX (0.25 mm phi x 30 m, film thickness 0.25 m)

Column temperature: 50 ° C

Carrier gas: nitrogen

Analysis time: 15 minutes

Sample injection volume: 1 μl

The amount of the solvent was determined by the following method.

With respect to each peak other than the solvent (methyl acetate) as the sample A, a calibration curve is obtained using the calibration curve, and the total sum thereof is referred to as Sa.

With Sample B, the ratio of each peak in the region hidden in the solvent peak in Sample A was calculated using a calibration curve, and the total sum thereof was defined as Sb.

The sum of Sa and Sb is called the residual solvent amount.

(4) Heat loss rate at 220 캜

When the sample was heated from room temperature to 400 占 폚 at a heating rate of 10 占 폚 / min under nitrogen using TG-DTA2000S manufactured by Mac Science Co., Ltd., the weight change of 10 mg of the sample at 220 占 폚 was measured by heating loss Rate.

(5) Melt viscosity

The measurement is carried out under the following conditions using a viscoelasticity measuring apparatus using a cone plate (for example, a modular compact rheometer: Physica MCR301 manufactured by Anton Paar).

After sufficiently drying the resin to adjust the water content to 0.1% or less, the shear rate (1 / sec) is measured at a temperature of 220 캜 and a gap of 500 탆.

(6) Re, Rth

The sample was sampled 10 times at equal intervals in the width direction of the film and conditioned at 25 DEG C and 60% rh for 4 hours. Thereafter, the sample was conditioned at 25 DEG C using an automatic birefringence meter (KOBRA-21ADH; manufactured by Oji Scientific Co., The retardation value at a wavelength of 590 nm is measured from a direction inclined at 10 DEG pitch from +50 DEG to -50 DEG from the film surface normal line in the direction perpendicular to the surface of the sample film and with the slow axis as the rotation axis at 60% RH The in-plane retardation value Re and the retardation value Rth in the film thickness direction were calculated.

Hereinafter, the features of the present invention will be described in more detail with reference to Examples and Comparative Examples. The materials, the amounts used, the ratios, the processing contents, the processing procedures, and the like shown in the following examples can be appropriately changed without departing from the gist of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below.

Example

In the film forming apparatus of the above-described touch-roll type cellulose-based resin (T ₀ = 240 ℃) or use of the thermoplastic resin of COC (T ₀ = 280 ℃) and, at the same time, film-forming a film by changing the extrusion temperature (T ₁₎ and the landing temperature , And the thickness deviation, stripe, retardation, color taste and strength decrease of each of the formed films were measured.

The thickness variation was measured using a TOFV1 type, an off-line contact type continuous thickness measuring instrument manufactured by YAMATO CHEMICAL INDUSTRIES, LTD., And measuring pitches at intervals of 1 mm. For the width direction, the total width of the film after trimming was measured, and for the flow direction, the length was measured to be 3 m.

The stripes were inspected by the naked eye and the retardation was measured as described above.

The yellowing index (YI value) was measured using a Z-II OPTICAL SNSOR according to JIS K7105 6.3. The pellet was measured by the reflection method, and the film was measured by three-pole value, X, Y, Z by the transmission method. The YI value was calculated by the following equation using the three stimulus values, X, Y, and Z. [

YI = {(1.28X-1.06Z) / Y} 100

The YI value of the film was calculated by dividing the YI value calculated in the above equation by the thickness of the film and converting the YI value per 1 mm.

The strength was evaluated by the impact strength per 80 탆.

The above results are shown in the table of FIG. In the table of Fig. 9, the evaluation of the thickness deviation was ⊚: 1 탆 or less, ∘: 5 탆 or less,?: 10 탆 or less, and x: 10 탆 or more. Evaluation of stripes was evaluated as?: Very good,?: Good,?: Slightly behind, and X: behind. ?: Both Re and Rth are all 5 nm or less,?: Both Re and Rth are all 10 nm or less, and at least one of x: Re and Rth is more than 10 nm. The color taste was evaluated as?: YI value per 1 mm was 5 or less,?: 8 or less,?: 10 or less, and x: 10 or more. A: The impact strength per 80 占 퐉 was 15 kg or more,?: 10 kg or more,?: 5 kg or more, and X: less than 5 kg.

As shown in the table of Fig. 9, in Test Example 1 in which the extrusion temperature (T ₁ ) was less than T ₀ -40 캜, the quality was deteriorated in terms of thickness deviation, streaking, and retardation. On the other hand, in Test Examples 2 to 8 in which the extrusion temperature (T ₁ ) was in the range of T ₀ -40 캜 to T ₀ + 30 캜 or less, satisfactory results were obtained in all the qualities. Particularly, good results were obtained in Test Examples 3 to 6, in which the extrusion temperature (T ₁ ) was 210 ° C to 240 ° C. Further, the higher the extrusion temperature (T ₁ ), the lower the quality in terms of coloration and strength reduction. In Test Example 9 exceeding T ₀ + 30 캜, sufficient quality was not obtained.

Test examples 10 to 14 are test results in which the landing temperature was changed with respect to the test example 4. As can be seen from the table of FIG. 9, in Test Example 10 in which the landing temperature was lower than the extrusion temperature (T ₁ ), defects in thickness deviation occurred. Also, in Test Example 14 in which the extrusion temperature (T ₁ ) exceeds +40, defects in thickness deviation occurred. On the other hand, in Test Examples 4 and 11 to 13 in which the landing temperature was in the range of the extrusion temperature (T ₁ ) to the extrusion temperature (T ₁ ) +40 or less, good results were obtained in terms of all the qualities.

Test Examples 15 to 20 are the test results in the case where the thermoplastic resin is COC (cyclic olefin copolymer). As can be seen from the table of FIG. 9, even in the case of COC, in the case of Test Example 15 in which the landing temperature is lower than the extrusion temperature (T ₁ ) and Test Example 15 in which the extrusion temperature (T ₁ ) , Good quality was obtained in Test Examples 16 to 19 in which the landing temperature was in the range of the extrusion temperature (T ₁ ) to the extrusion temperature (T ₁ ) +40 or less.

Next, a cellulose resin was used, and the same test was conducted by changing the line pressure. The results are shown in the table of Fig.

As can be seen from the table shown in Fig. 10, in the case of using the touch roll method, when the line pressure is 0.05 or less, the sheet is unevenly inserted in the width direction, thereby causing a problem of deteriorating the thickness deviation. In Test Example 22 in which the line pressure was less than 0.05 MPa, the quality deteriorated in terms of the thickness deviation and the streaks. In Test Example 25 in which the line pressure exceeded 1.5 MPa, retardation was expressed, while the line pressure was 0.05 to 1.5 MPa In Test Examples 23 to 24 and Test Example 4, good results were obtained in all aspects of thickness deviation, stitching, and retardation.

Claims (9)

A method for producing a thermoplastic resin film by extruding a thermoplastic resin melted in an extruder into a sheet form on a cooling roller rotating from a die and cooling and solidifying the film, When the thermoplastic resin is allowed to stand in a nitrogen atmosphere for one hour and the temperature at which the heat loss becomes 0.30 wt% is T ₀ , An extrusion step of extruding the melted thermoplastic resin at an extrusion temperature (T ₁ ) at the time of extruding the thermoplastic resin from the extruder at a temperature of T ₀ -40 ° C to T ₀ + 30 ° C; And And a heating step of heating the extruded thermoplastic resin to a landing temperature equal to or higher than the extrusion temperature until the extruded thermoplastic resin land on the cooling roller, Wherein the thermoplastic resin is a cellulose resin and the extrusion temperature (T ₁ ) is 200 ° C to 260 ° C. The method for producing a thermoplastic resin film according to claim 1, wherein the upper limit of the landing temperature is T ₁ + 40 ° C. delete delete The method for producing a thermoplastic resin film according to claim 1, wherein the thermoplastic resin from the extrusion to the landing is heated with a far-infrared heater having a center wavelength of 2.1 mu m to 3.7 mu m. The method for producing a thermoplastic resin film according to claim 1 or 2, wherein the thermoplastic resin extruded from the die and landed on the cooling roller is nipped by the cooling roller and the touch roller. The method of manufacturing a thermoplastic resin film according to claim 6, wherein the touch roller is an elastic roller. The method for producing a thermoplastic resin film according to claim 6, wherein the linear pressure at which the cooling roller and the touch roller nip the sheet-shaped thermoplastic resin is set to 0.05 to 1.5 MPa. delete

Images