KR20100081938A - Device for stretching thermoplastic resin film, and method of producing optical film - Google Patents

Abstract

PURPOSE: An extending device of a thermoplastic resin film and a method for manufacturing an optical film are provided to suppress failure of optical deviation. CONSTITUTION: An edge cutting device(25) is installed between a tender unit(12) and a heat reducing unit(13). The edge cutting device cuts an edge of an optical film(24). A cut blower(26) cuts the cut edge by pieces. A crusher(27) crushes the pieces transferred by a blowing device. A plurality of rollers(28) is installed in the heat reducing unit. A roller returns an optical film to a cooler(14). The optical unit cools the optical film up to a fixed temperature.

Description

Drawing apparatus of a thermoplastic resin film, and the manufacturing method of an optical film TECHNICAL FIELD [DEVICE FOR STRETCHING THERMOPLASTIC RESIN FILM, AND METHOD OF PRODUCING OPTICAL FILM}

This invention relates to the stretching apparatus of a thermoplastic resin film, and the manufacturing method of an optical film.

Since a thermoplastic resin film (henceforth a film) has the characteristics, such as excellent light transmittance and flexibility, light weight thinning, etc. are used, it is used for various uses as an optical film. Among them, TAC films formed from cellulose acylate films, in particular cellulose triacetate (hereinafter referred to as TAC) having an average degree of oxidation of 57.5% to 62.5%, have excellent toughness and flame retardancy, so they are used for films of photosensitive materials. It is used as a support body. Moreover, since TAC film is excellent in optical isotropy among films, it is used as optical films, such as a protective film, a retardation film, and a viewing angle expansion film, of the polarizing plate of a liquid crystal display device.

As a manufacturing method of a film, there exists a melt extrusion method and a solution film forming method. The melt extrusion method is a manufacturing method in which a polymer is heated as it is to melt, and the melted polymer is extruded in an extruder to form a film. This method is characterized by high productivity and relatively low equipment cost. On the other hand, in the solution film forming method, a polymer solution containing a polymer and a solvent (hereinafter referred to as dope) is cast on a support to form a flexible film, and after the formed flexible film has a self-supporting property, It is a manufacturing method which peels this casting film from a support body, and sets it as a film and this film is fully dried.

The optical film is required to have uniform optical characteristics such as retardation. Therefore, in Japanese Patent Laid-Open No. 2002-296422, in order to make the optical properties such as retardation uniform in the width direction of the film, the film is heated, and both ends in the width direction of the film (hereinafter referred to as edge portions). The method of holding | gripping with a clip etc. and extending | stretching a film in the width direction is proposed.

By the way, even if it was the optical film obtained by the above extending | stretching process, the malfunction (hereafter called an "optical deviation failure") in which the optical characteristic was nonuniform in the width direction still occurred.

As a result of earnestly examining, the inventors found that the occurrence of the optical deviation failure can be suppressed by suppressing the temperature nonuniformity in the width direction in the film at the start of the stretching treatment. An object of the present invention is to provide a stretching apparatus for stretching a thermoplastic resin film while suppressing occurrence of optical deviation failure, and a method for producing an optical film for stretching a thermoplastic resin film.

The stretching apparatus of a thermoplastic resin film is equipped with a running part, a 1st hot air supply part, a 2nd hot air supply part, a extending | stretching part, and a direction adjusting part. The running portion drives the thermoplastic resin film. The thermoplastic resin film sequentially passes through the preheating area and the drawing area formed in the tenter by running by the traveling part. The first hot air supply unit injects the first hot air to the thermoplastic resin film traveling through the preheating area. The first hot air is air having a higher temperature than the tenter outside air outside the tenter. A 2nd hot air supply part injects 2nd hot air to the said thermoplastic resin film which travels the said drawing area. The second hot air is at a temperature equal to or higher than the temperature of the first hot air. The extending | stretching part extends the said thermoplastic resin film which travels the said drawing area. The stretching section stretches the thermoplastic resin film in a direction orthogonal to the traveling direction. The direction adjustment unit adjusts the direction in which the second hot air flows at the boundary between the preheating area and the stretching area. The direction in which the second hot air flows at the boundary is a direction from the drawing area toward the preheating area by the direction adjusting unit.

It is preferable that the said direction adjusting part has a blowing nozzle provided in the said drawing area, the said blowing nozzle is formed so that it may extend toward the said boundary, and the blowing nozzle which blows out the said 2nd hot air is formed in the front-end | tip of the said blowing nozzle. Do. The jet port has a slit shape and is preferably elongated in the stretching direction.

The direction adjusting portion has a suction nozzle provided in the preheating area, the suction nozzle is formed to extend toward the boundary, and a suction port for sucking the second hot air is formed at the tip of the suction nozzle. desirable. It is preferable that the suction port has a slit shape and is formed to elongate in the stretching direction.

The manufacturing method of an optical film has a preheating step, an extending | stretching step, and a direction adjustment step. The preheating step injects the first hot air into the thermoplastic resin film traveling through the preheating area. The first hot air has a higher temperature than the tenter outside air outside of the tenter. The preheating area is formed inside the tenter. An extending step injects 2nd high temperature air to the said thermoplastic resin film which travels a drawing area, and extends the said thermoplastic resin film to the direction orthogonal to the said running direction. The second hot air is at a temperature equal to or higher than the temperature of the first hot air. The stretching area is formed inside the tenter, and is located in the running direction downstream from the preheating area. The direction adjustment step adjusts the direction in which the second hot air flows at the boundary between the preheating area and the stretching area. The direction in which the second hot air at the boundary flows by the adjustment is a direction from the drawing area toward the preheating area.

In the direction adjusting step, it is preferable to send the second hot air from the downstream side in the travel direction toward the boundary. In the direction adjusting step, it is preferable to suck the second hot air on the upstream side of the traveling direction from the boundary. It is preferable to flow the second hot air at a uniform flow rate in the stretching direction.

It is preferable that the said thermoplastic resin film is made by the solution film forming method.

The thermoplastic resin contains cellulose acylate or cyclic polyolefin.

In this invention, a thermoplastic resin film is made to drive a preheating area and an extending | stretching area sequentially. The preheating area is filled with the first hot air having a higher temperature than the air outside the tenter. The stretching area is filled with second hot air having a higher temperature than the first hot air. In the stretching area, the thermoplastic resin film is stretched in a direction orthogonal to the traveling direction. At the boundary between the preheating area and the stretching area, hot air can flow from the stretching area toward the preheating area. For this reason, inflow of 1st high temperature air to the extending | stretching area is interrupted | blocked. As a result, generation | occurrence | production (temperature nonuniformity) of the temperature deviation in a extending | stretching direction with respect to the thermoplastic resin film at the start of an extending | stretching process can be suppressed. Therefore, according to this invention, it becomes possible to suppress generation | occurrence | production of the optical deviation failure resulting from the temperature variation of the thermoplastic resin film at the start of an extending | stretching process.

The above objects and advantages will be readily understood by those skilled in the art by referring to the accompanying drawings and reading the specific contents for carrying out the invention.

1 is a schematic diagram of an offline stretching apparatus.
2 is a top view showing an outline of a tenter portion.
3 is a cross-sectional view showing an outline of a tenter portion and a duct.
4 is a perspective view showing an outline of the blowing head.
5 is a cross-sectional view showing an outline of a blowing head.
It is sectional drawing which shows the outline | summary of a suction head and a blowing head.
7 is a schematic view of a solution film production facility.

(Offline drawing device)

As shown in FIG. 1, the offline stretching apparatus 10 includes a supply section 11, a tenter section 12, a thermal relaxation section 13, a cooling section 14, and a winding section 15. Doing. In the supply part 11, the elongate thermoplastic resin film 20 is accommodated. This film 20 is manufactured by the solution film forming method mentioned later. The film 20 accommodated in the supply part is roll-shaped and wound by the winding core 21. The film 20 wound up by the winding core 21 is sent to the tenter part 12 by the supply roller 22, and it becomes the optical film 24. FIG. The optical film 24 is sequentially sent to the heat relaxing part 13, the cooling part 14, and the winding-up part 15. The film 20 and the optical film 24 are subjected to predetermined treatments at the respective portions 12 to 15.

The tenter portion 12 has a casing 16, as shown in FIG. 2. The casing 16 is formed with an inlet 16a for introducing the film 20 and an outlet 16b for sending the film 20 to the outside of the tenter portion 12. Moreover, the conveyance path of the film 20 is formed in the casing 16 from the inlet 16a to the outlet 16b. In the conveyance path of the film 20, the edge part of the film 20 is gripped and the film 20 is conveyed in the longitudinal direction (henceforth direction Z1) of the film 20. In the conveyance path, the extending | stretching process of extending | stretching in the width direction (it is called a direction Z2 hereafter) of the film 20 is performed, conveying the film 20. The structure and extension process of the tenter part 12 are mentioned later.

As shown in FIG. 1, the edge siltting device 25 is provided between the tenter part 12 and the heat relaxation part 13. As shown in FIG. The edge cutting device 25 cuts the edge portion of the optical film 24. The cut edges are cut into fine pieces in the cut blower 26. The small pieces are sent to a crusher 27 by a blower not shown, and are crushed into chips.

The heat relaxation part 13 is provided with a number of rollers 28. The optical film 24 is conveyed to the cooling part 14 by these rollers 28. In addition, in the heat relaxation part 13, dry wind is sprayed with respect to the optical film 24 in conveyance. In the cooling unit 14, the optical film 24 is cooled to a predetermined temperature.

The cooled optical film 24 is sent to the winding-up part 15. The winding unit 15 is provided with a winding device having a winding core 30 and a press roller 31, and the optical film 24 is wound around the winding core 30 while being pressed by the press roller 31.

(Tenter part)

As shown in FIG. 2, the casing 16 is divided into the preheating area 36a, the drawing area 36b, the relaxation area 36c, and the cooling area 36d sequentially on the upstream side of the direction Z1. In addition, the relaxation area 36c may be omitted.

As shown in FIGS. 2 and 3, the tenter portion 12 includes a clip 40, rails 41 and 42, and a blower 43 inside the casing 16. The rails 41 and 42 are provided on both sides of the conveyance path of the film 20. Each of the rails 41 and 42 is spaced apart by a predetermined rail width.

The chain (not shown) is attached to the rail 41 and 42 so that a movement is possible. The plurality of clips 40 are attached to the entire chain at predetermined intervals. In addition, in FIG. 2, only a part of the clip 40 is shown in order to avoid the trouble of drawing. The chain is in engagement with the sprockets 48 and 49. As the sprockets 48 and 49 rotate, the clip 40 moves along the rails 41 and 42. A holding start means (not shown) is provided at a position Pa near the inlet 16a on the rails 41 and 42. The gripping initiation means initiates gripping of the edge portion of the film 20 by the clip 40. Gripping release means (not shown) is provided at the position Pb near the outlet 16b on the rails 41 and 42. The gripping release means releases the gripping of the edge portion of the film 20 by the clip 40. When the clip 40 passes through the position Pa on the rails 41 and 42, the clip 40 starts to grip the edge portion of the film 20. When the clip 40 passes through the position Pb on the rails 41 and 42, the clip 40 releases the grip of the edge portion of the film 20.

In addition, the rail widths of the rails 41 and 42 in the stretching area 36b gradually increase from the stretching start position Pc to the stretching completed position Pd toward the direction Z1. The stretching start position Pc is a position where the stretching process is started. The stretching completion position Pd is a position where the stretching processing is completed. On the other hand, the rail width of the rails 41 and 42 in the relaxation area 36c gradually narrows toward the direction Z1. In addition, the rail widths of the rails 41 and 42 in the preheating area 36a and the cooling area 36d are constant.

In this way, as the clip 40 moves along the rails 41 and 42, the film 20 is conveyed in the direction Z1 and sequentially passes through each of the areas 36a to 36d, and predetermined in each of the areas 36a to 36d. Processing is carried out.

(Blower)

As shown in FIG.3 and FIG.4, the blower 43 is equipped with many blower heads 52a-52d, the transfer duct 53, the return duct 54, and the dry air supply part 55. As shown in FIG. .

(Blowing head)

As shown in FIG. 5, the some blowing head 52a-52c is installed above the conveyance path of the film 20, respectively. Although illustration is abbreviate | omitted, the blowing head 52d is also provided above the conveyance path of the film 20 similarly to blowing heads 52a-52c. As shown in FIG. 3 and FIG. 4, the blowing head 52a is provided in the preheating area 36a, and the blowing head 52b is provided in the extending area 36b. Similarly, the blowing heads 52c-52d are provided in each area 36c-36d.

The head internal duct 56a is formed inside the blowing head 52a. The blowing head 52a has a plurality of jet nozzles 60a. The plurality of jet nozzles 60a are arranged to be arranged at a predetermined pitch in the direction Z1. The tip of the jet nozzle 60a is formed to extend toward the conveyance path of the film 20. A jet port 61a is formed at the tip of the jet nozzle 60a. The jet port 61a has a slit shape and is formed long in the direction Z2. The jet port 61a of the jet nozzle 60a communicates with the head internal duct 56a. Blowing heads 52c-52d have blowing nozzles 60c-60d, such as blowing nozzle 60a, and are formed in the same structure as blowing head 52a.

The head internal duct 56b is formed in the blowing head 52b. The blowing head 52b has a jet nozzle 60b and a jet nozzle 60x. The jet nozzle 60b and the jet nozzle 60x are provided in order from the downstream in the Z1 direction to the upstream. The front end of the jet nozzle 60b and the jet nozzle 60x is formed so that it may respectively extend toward the conveyance path of the film 20. Jetting ports 61b and 61x are formed at the tip of the jetting nozzle 60b and the jetting nozzle 60x. The ejection openings 61b and 61x have a slit shape and are formed long in the direction Z2. The jet ports 61b and 61x communicate with the head internal duct 56b.

As shown in FIG.4 and FIG.5, the front-end | tip of each jet nozzle 60a-60d is formed so that it may extend in the direction orthogonal to the conveyance path of the film 20. As shown to FIG. The tip of the jet nozzle 60x is formed so as to face the boundary of the preheating area 36a and the extending area 36b.

As shown in FIG.3 and FIG.4, the transfer duct 53 is provided in the side surface of each blowing head 52a-52d. The conveying duct 53 communicates with the head inner ducts 56a and 56b (not shown in the head inner duct of the blowing head 52d) of the blowing heads 52a to 52d and the dry air supply unit 55. The return duct 54 which connects with the dry air supply part 55 is provided in the both sides of the conveyance path of the film 20. As shown in FIG.

The dry air supply part 55 is provided with the circulation fan (not shown) for circulating air. The dry air supply unit 55 sends dry air to each of the blowing heads 52a to 52d through the transfer duct 53 using the circulation fan, and supplies the air inside the casing 16 through the return duct 54. Recover. The recovered air is subjected to condensation treatment by a condenser not shown in the figure. The solvent is removed from the air recovered by the condensation treatment. The condensed air is sent back to each of the blowing heads 52a to 52d by the circulation fan. The dry air sent to each blowing head 52a-52d conveys the film 20 from each blowing nozzle 60a-60d, 60x after temperature is adjusted in predetermined range with the temperature controller not shown in the figure. It is sent toward the furnace.

Next, the operation of the present invention will be described. As shown in FIG. 1, the feed roller 22 becomes a roll shape and sends the film 20 wound by the winding core 21 to the tenter part 12. As shown in FIG. The film 20 which passed the tenter part 12 turns into the optical film 24, and is sent to the edge cutting device 25. As shown in FIG. After the edge part is cut | disconnected by the edge cutting device 25, the optical film 24 is sent to the winding-up part 15 through the heat relaxation part 13 and the cooling part 14. As shown in FIG.

As shown in FIG. 2, the film 20 sent to the tenter part 12 is sent to the preheating area 36a. The clip 40 which runs along the rails 41 and 42 grips the edge part of the film 20 by the holding | gripping start means which is not shown in figure in the position Pa. Then, the clip 40 travels in the direction Z1 while holding the edge portion, so that the film 20 moves from the upstream side to the downstream side in the direction Z1 to the preheating area 36a, the stretching area 36b, and the relaxation area 36c. And the cooling area 36d sequentially. It is preferable that the traveling speed of the film 20 is 5 m / min or more and 200 m / min or less.

As shown in FIG.3 and FIG.4, the dry air supply 55 supplies air to each blowing head 52a-52d. By the temperature controller which is not shown in figure, the temperature of the air sent to each blowing head 52a-52d is adjusted so that it may become in a predetermined range, respectively. The air sent to each of the blowing heads 52a to 52d flows from the jet nozzles 60a to 60d toward the film 20 at a uniform flow rate in the direction Z2 and contacts the film 20. Air in the casing 16 is also recovered to the dry air supply 55 through the return duct 54.

The temperature of the air in the blowing head 52a is higher than the temperature of the air outside the tenter portion 12, but is lower than the temperature of the air in the blowing head 52b. Thus, the temperature of the air in the preheating area 36a is lower than the temperature of the air in the stretching area 36b, and the temperature of the film 20 in the stretching area 36b is in the preheating area 36a. It will be in a state higher than the temperature of the film 20.

At the position Pc of the stretching area 36b, the stretching treatment for stretching the film 20 in the direction Z2 is started. By the way, as the film 20 travels, air lower in temperature than the air in the stretching area 36b flows from the preheating area 36a toward the stretching area 36b in the vicinity of the surface of the film 20. And since low-temperature air flows into the extending | stretching area 36b, the temperature difference of the direction Z2 arises in the film 20 in the boundary of the preheating area 36a and the extending | stretching area 36b. The temperature deviation means a phenomenon in which the temperature is uneven or a phenomenon of becoming uneven. The temperature of the film 20 in the stretching treatment, and especially the temperature of the film 20 at the start of the stretching treatment greatly affects the deformation of the film 20 and the orientation of the polymer molecules in the stretching treatment. . Therefore, when extending | stretching of the direction Z2 is started with respect to the film 20 of the state in which the temperature deviation was shown in the direction Z2, the optical deviation failure will arise in the direction Z2 in the film 20 after an extending | stretching process.

On the other hand, in this invention, the front end is provided with the jet nozzle 60x extended so that it may face the boundary of the preheating area 36a and the extending | stretching area 36b, and the jet port 61x formed in the front-end | tip of this jet nozzle 60x. The blowing head 52b is used. For this reason, the air of the same temperature as the air in extending | stretching area 36b in the surface vicinity of the film 20 can flow from extending | stretching area 36b toward the preheating area 36a. This can prevent the low-temperature air in the preheating area 36a from flowing into the stretching area 36b. Therefore, the temperature of the film 20 in position Pc, ie, when an extending | stretching process is started, becomes uniform in the direction Z2. For this reason, according to this invention, generation | occurrence | production of the optical deviation failure in the direction Z2 in the optical film 24 can be suppressed.

Moreover, since the jet port 61x is formed in the slit shape extended long in the direction Z2, it becomes possible to make the flow volume of the air sent out toward the film 20 uniform in the direction Z2. As a result, the nonuniformity of the temperature of the film 20 at the start of an extending | stretching process, ie, the nonuniformity of a temperature, can be suppressed reliably.

It is preferable that the temperature of the air in the inside of the blowing head 52a is adjusted within the range of 40 degreeC or more and 240 degrees C or less. And it is preferable that the temperature of the film 20 in the preheating area 36a is adjusted within 30 to 220 degreeC.

The temperature of the air inside the blowing head 52b, that is, the air inside the head inner duct 56a, is preferably adjusted within a range of 100 ° C or more and 270 ° C or less. And it is preferable that the temperature of the film 20 in the extending | stretching area 36b is adjusted within the range of 100 degreeC or more and 250 degrees C or less. Moreover, it is preferable that residual solvent amount of the film 20 in the extending | stretching area 36b is 0 weight% or more and 3 weight% or less. The residual solvent amount of the film 20 is obtained by taking a sample film from the target film, and when the weight of the sample film at the time of collection is x and the weight after drying the sample film is y, {(xy) / y} × It is represented by 100. When the width of the film 20 at the position Pc is L1 and the width of the film 20 at the position Pd is L2, the elongation ER (%) in the stretching treatment is (L2-. It is represented by L1) / L1x100. Elongation (ER) is preferably greater than 0% and 400% or less.

Although the ejection nozzle 60x was provided as the ejection nozzle of the most upstream of the direction Z1 among the ejection nozzles provided in the blowing head 52b in the said embodiment, this invention is not limited to this, It is provided in the upstream of the direction Z1. A plurality of jet nozzles may be used as the jet nozzles 60x, or all of the jet nozzles provided in the blowing head 52b may be nozzles 60x.

As shown in FIG. 6, you may provide the suction head 65 between the blowing heads 52a and 52b. The suction head 65 is provided with a suction nozzle 65b having a suction port 65a. The suction nozzle 65b is formed to extend toward the boundary between the preheating area 36a and the stretching area 36b. Under the control of a controller not shown in the figure, the suction nozzle 65b sucks air at the boundary between the preheating area 36a and the stretching area 36b, so that the suction nozzle 65b reaches the stretching area 36b near the surface of the film 20. Existing air can be flowed from extending | stretching area 36b toward the preheating area 36a. In this invention, this suction nozzle 65b may be used independently and may be used together with the above-mentioned jet nozzle 60x.

In the said embodiment, although the air of the same temperature as the air supplied to the extending | stretching area 36b flowed toward the direction opposite to the direction Z1 through the position Pc, this invention is not limited to this, The extending | stretching area 36b ), The supply amount of air supplied to the blowing head 52a and the supply amount of air supplied to the blowing head 52b may be adjusted so that the pressure in the air pressure is higher than that in the preheating area 36a.

When the air pressure in the stretched area 36b is approximately the same as the air pressure in the blowing head 52b during operation of the tenter portion 12, the air blowing head 52b is used to start the tenter portion 12. After supplying air to the stretching area 36b, it is preferable to supply air to the preheating area 36a through the blowing head 52a.

In addition, when the film 20 passes through the inlet 16a, air outside the tenter portion 12 flows into the tenter portion 12 from the inlet 16a and is inside the tenter portion 12. The air is cooled As a result, foreign matters and the like are liquefied and solidified from the air inside the tenter portion 12. Each component, such as the casing 16 in the tenter part 12, may become contaminated by liquefaction or solidification, such as a foreign material. As this foreign material, the solvent evaporated from the film 20, an additive (for example, a plasticizer, a retardation control agent), etc. are contained. In order to prevent such a tenter portion 12 from being contaminated, a closed air member that blocks a part of the inlet portion 16a may be provided at the inlet portion 16a of the tenter portion 12. Thereby, when the film 20 passes the inlet 16a, the air which is outside the tenter part 12 can be prevented from flowing into the tenter part 12 as the film 20 runs. .

(Optical film)

The optical film 24 obtained by this invention can be used especially for retardation film and a polarizing plate protective film.

It is preferable that it is 600 mm or more, and, as for the width | variety of the optical film 24, it is more preferable that they are 1400 mm or more and 2500 mm or less. Moreover, this invention is effective also when the width | variety of the optical film 24 is larger than 2500 mm. Moreover, it is preferable that the film thickness of the optical film 24 is 30 micrometers or more and 120 micrometers or less.

Moreover, it is preferable that in-plane retardation Re of the optical film 24 is 0 nm or more and 300 nm or less, and it is preferable that the thickness direction retardation Rth of the optical film 24 is -100 nm or more and 300 nm or less. It is preferable that deviation (DELTA) Re of in-plane retardation Re in direction Z2 is 10 nm or less, and it is preferable that the deviation (DELTA) Rth of thickness direction retardation Rth in direction Z2 is 20 nm or less.

The measurement method of the deviation (DELTA) Re of in-plane retardation Re and the deviation (DELTA) Rth of thickness direction retardation Rth are as follows. Twenty sample films were equally cut out from the optical film 24 in the direction Z2, and in-plane retardation Re and thickness direction retardation Rth were measured for each sample film. The maximum value of Re is called Re _max and the minimum value is Re _min . ΔRe is represented by (Re _max -Re _min ). The maximum value of the measurements of Rth is called Rth _max , and the minimum value is called Rth _min . ΔRth is represented by (Rth _max −Rth _min ).

The measuring method of in-plane retardation Re is as follows. First, a sample film is humidified (humidity adjustment) for 2 hours at the temperature of 25 degreeC, and 60% of humidity. The retardation value measured from the vertical direction in 632.8 nm by the automatic birefringence meter (KOBRA21DH Oji Keisoku Co., Ltd.) was made into in-plane retardation (Re). Re is represented by the following formula.

Re = | n1-n2 | × d

n1 is the refractive index of the direction Z1, n2 is the refractive index of the direction Z2, and d shows the thickness (film thickness) of a film.

The measuring method of thickness direction retardation Rth is as follows. First, the sample film was humidified for 2 hours at the temperature of 25 degreeC, and 60% of humidity. Thus, the sample film subjected to the humidity treatment was measured from the vertical direction at 632.8 nm with an epimeter (M150 Nippon Bunco Co., Ltd.) and from the external insertion value of the retardation value measured similarly while tilting the film surface. It computed according to the following formula.

Rth = {(n1 + n2) / 2-n3} × d

n3 represents the refractive index of the thickness direction.

This invention can be applied to the solution film forming method performed by the solution film forming installation 80 shown in FIG. In addition, about the apparatus and member similar to the said embodiment, the same code | symbol is attached | subjected and the description of the detail is abbreviate | omitted. The solution film forming facility 80 has a stock tank 81, a flexible chamber 82, a tenter portion 12, a drying chamber 83, a cooling unit 14, and a winding unit 15.

The stock tank 81 is provided with the stirring blade 81b and the jacket 81c which rotate by the motor 81a, The dope 91 used as a raw material of the film 20 is stored inside. The dope 91 in the stock tank 81 is adjusted so that temperature may become substantially constant with the jacket 81c. Moreover, the dope 91 is maintained in uniform quality, by suppressing aggregation of a polymer etc. by rotation of the stirring blade 81b. Downstream of the stock tank 81, a gear pump 92 and a filtration device 93 are provided, through which the dope 91 is sent to the flexible die 95.

The casting chamber 82 is provided with a casting die 95, a casting drum 96 as a support, a peeling roller 97, a thermostats 98 and 99, and a pressure reducing chamber 100. The casting drum 96 is rotated in the direction A1 about the axis 96a by a drive device (not shown). The flexible die 95 has slits formed to extend in the width direction. The dope 91 discharges from the slit of the casting die 95 toward the peripheral surface of the casting drum 96 during this rotation, and the casting film 103 is formed in the peripheral surface of the casting drum 96.

The casting chamber 82 and the casting drum 96 are set to a temperature at which the casting membrane 103 is easily solidified (gelled) by the temperature controllers 98 and 99. And while the casting drum 96 rotates about 3/4, the casting film 103 reaches the gel strength which has self-support, peels from the casting drum 96 by the peeling roller 97, and the wet film 104 is carried out. ) When the circumferential speed of the flexible drum 96 is V1 and the circumferential speed of the peeling roller 97 is V2, the control part which is not shown in figure shows so that V2 / V1 may be 101% or more and 150%, and the flexible drum 96 and the peeling roller Drive 97 in rotation.

The pressure reduction chamber 100 is arrange | positioned upstream of the direction A1 with respect to the casting die 95, and has maintained the inside of the pressure reduction chamber 100 at negative pressure. This reduces the back side of the flexible bead (behind, the surface in contact with the circumferential surface of the flexible drum 96) at a desired pressure, and reduces the influence of the accompanying wind generated by the rotating of the flexible drum 96 at high speed. A stable cast bead is formed between the cast die 95 and the cast drum 96, and a cast film 103 having a small film thickness variation is formed.

The flexible chamber 82 is provided with a condenser (condenser) 109 for condensing and recovering the evaporated organic solvent and a recovery device 110 for recovering the condensed liquefied solvent. The organic solvent condensed and liquefied in the condenser 109 is recovered by the recovery device 110. The recovered solvent is recycled in the regeneration apparatus and then reused as a dope preparation solvent.

Downstream of the flexible chamber 82, the moving part 111, the pin tenter 112, and the tenter part 12 are provided in order. The moving part 111 introduces the wet film 104 into the pin tenter 112 using the some conveyance roller 113. The pin tenter 112 has a plurality of pin plates that hold both ends of the wet film 104, which pin plates travel on the track. Dry wind is sent to the wet film 104 during this travel, and the wet film 104 is dried while traveling to form the film 20.

The wet film 104 is preferably dried until the amount of residual solvent in the pin tenter 112 becomes 0.1 wt% or more and 10 wt% or less. The cellulose acyl in the tenter part 12 is peeled off when the amount of residual solvent is in the range of 150 weight% or more and 320 weight% or less, and it dries until the amount of residual solvent in the pin tenter 112 becomes the said range. The orientation control of the rate molecule is performed more effectively. That is, the direction control effect of the slow axis in the extending | stretching process in the tenter part 12, the effect of raising Re and Rth, and the improvement effect of an optical deviation become high. In the present invention, however, the drying in the pin tenter 112 may not be performed until the residual solvent amount is within the above range. That is, you may send the wet film 104 to the tenter part 12 with a residual solvent amount higher than 10 weight%.

In the drying chamber 83, the drying film of 50 degreeC or more and 200 degrees C or less is sprayed on the optical film 24, and the optical film 24 is dried. In the drying chamber 83, it is preferable to dry the optical film 24 until the amount of residual solvent becomes 0.01 weight% or more and 5 weight% or less.

Although the tenter part 12 was installed between the pin tenter 112 and the drying chamber 83, this invention is not limited to this, The tenter part 12 is provided between the cooling part 14 and the winding-up part 15, You may provide the tenter part 12 between the pin tenter 112 and the drying chamber 83, and between the cooling part 14 and the winding-up part 15. FIG. In addition, when extending | stretching process using the tenter part 12 of the offline stretching apparatus 10 with respect to the film manufactured by the solution film-forming installation 80, the tenter part 12 in the solution film-forming installation 80 is carried out. May be omitted.

The film 20 of the said embodiment is not limited to the film obtained by the above-mentioned solution film forming method, The film obtained by a melt film forming method is also included.

(Polymer)

The polymer which can be used for this invention will not be specifically limited if it is a thermoplastic resin, For example, a cellulose acylate, a lactone ring containing polymer, a cyclic olefin, a polycarbonate etc. are mentioned. Among them, preferred are cellulose acylates and cyclic olefins. Among these, preferred are cellulose acylates containing acetate groups and propionate groups and cyclic olefins obtained by addition polymerization, and more preferably cyclic olefins obtained by addition polymerization. .

(Cellulose acylate)

As cellulose acylate, cellulose triacetate (TAC) is particularly preferable. The degree of substitution of the acyl group to the hydroxyl group of the cellulose among the cellulose acylates in the following formulas (I) to (III), wherein A and B represent the degree of substitution of the acyl group with respect to the hydrogen atom in the hydroxyl group of the cellulose, and A Is a substitution degree of an acetyl group, B is a substitution degree of the acyl group of 3-22 carbon atoms. Moreover, it is preferable that 90 weight% or more of TAC is 0.1-4 mm particle | grains. However, the polymer which can be used for this invention is not limited to a cellulose acylate.

(I) 2.5 ≦ A + B ≦ 3.0

(II) 0 ≤ A ≤ 3.0

(III) 0 ≤ B ≤ 2.9

The glucose units bound to β-1,4 constituting cellulose have free hydroxyl groups at the 2, 3, and 6 positions. Cellulose acylate is a polymer (polymer) in which some or all of these hydroxyl groups are esterified by acyl groups having 2 or more carbon atoms. Acyl substitution degree means the ratio (the substitution degree 1 is called the case of 100% esterification) in which the hydroxyl group of a cellulose is esterified with respect to 2-position, 3-position, and 6-position, respectively.

As for the total acylation substitution degree, ie, the value of DS2 + DS3 + DS6, 2.00-3.00 are preferable, More preferably, it is 2.22-2.90, Especially preferably, it is 2.40-2.88. The value of DS6 / (DS2 + DS3 + DS6) is preferably 0.28, more preferably 0.30 or more, and particularly preferably 0.31 to 0.34. Here, DS2 is a ratio where hydrogen of the 2-position hydroxyl group in a glucose unit is substituted by an acyl group (henceforth "acyl substitution degree of 2-position"), and DS3 is a 3-position hydroxyl group in a glucose unit. Of hydrogen is substituted by an acyl group (hereinafter referred to as "acyl substitution degree at 3-position"), and DS6 is a ratio where hydrogen of a 6-position hydroxyl group is substituted by an acyl group in the glucose unit (hereinafter referred to as "6-position" Acyl substitution degree.

Only one kind of acyl group may be used for the cellulose acylate of the present invention, or two or more kinds of acyl groups may be used. When using two or more types of acyl groups, it is preferable that one is an acetyl group. The total sum of the degree to which the hydroxyl groups at the 2, 3 and 6 positions are substituted by the acetyl group is called DSA, and the total degree to which the hydroxyl groups at the 2, 3 and 6 positions are substituted by the acyl groups other than the acetyl group. When the sum is DSB, the value of DSA + DSB is preferably 2.22 to 2.90, particularly preferably 2.40 to 2.88.

Moreover, it is preferable that DSB is 0.30 or more, Especially preferably, it is 0.7 or more. Moreover, it is preferable that 20% or more of DSB is a substituent of the hydroxyl group of a 6-position, More preferably, it is 25% or more, More preferably, 30% or more, It is preferable that it is especially 33% or more. Moreover, the value of DSA + DSB in the 6-position of a cellulose acylate is 0.75 or more, More preferably, it is 0.80 or more, Especially the cellulose acylate which is 0.85 or more is also preferable, More soluble by using these cellulose acylates It is possible to produce this excellent dope. In particular, when a non-chlorinated organic solvent is used, a dope having excellent solubility and excellent filterability at low viscosity can be produced.

The cellulose which is a raw material of cellulose acylate may be obtained from any one of a linter and a pulp.

As a C2 or more acyl group of the cellulose acylate in this invention, an aliphatic group or an aryl group may be sufficient, and is not specifically limited. For example, alkyl carbonyl ester, alkenyl carbonyl ester, aromatic carbonyl ester, aromatic alkyl carbonyl ester of cellulose, etc. are mentioned, You may have group substituted further, respectively. As preferable examples thereof, propionyl group, butanoyl group, pentanoyl group, hexanoyl group, octanoyl group, decanoyl group, dodecanoyl group, tridecanoyl group, tetradecanoyl group, hexadecanoyl group, octadecanoyl group, iso -Butanoyl group, t-butanoyl group, cyclohexanecarbonyl group, oleoyl group, benzoyl group, naphthylcarbonyl group, cinnamoyl group, etc. are mentioned. Among these, propionyl group, butanoyl group, dodecanoyl group, octadecanoyl group, t-butanoyl group, oleoyl group, benzoyl group, naphthylcarbonyl group, cinnamoyl group and the like are more preferable, and particularly preferably propionyl Group, butanoyl group.

(solvent)

As a solvent for preparing the dope, an aromatic hydrocarbon (for example, benzene, toluene, etc.), a halogenated hydrocarbon (for example, dichloromethane, chlorobenzene, etc.), an alcohol (for example, methanol, ethanol, n-propanol, n-butanol, di Ethylene glycol, etc.), ketones (e.g. acetone, methyl ethyl ketone, etc.), esters (e.g. methyl acetate, ethyl acetate, propyl acetate, etc.) and ethers (e.g., tetrahydrofuran, methyl cellosolve, etc.) Can be mentioned.

Among the halogenated hydrocarbons, halogenated hydrocarbons having 1 to 7 carbon atoms are preferably used, and dichloromethane is most preferably used. From the viewpoints of physical properties such as TAC solubility, peelability from the support of the flexible membrane, mechanical strength and optical properties of the film, it is preferable to mix one or several alcohols having 1 to 5 carbon atoms in addition to dichloromethane. As for content of alcohol, 2-25 weight% is preferable with respect to the whole solvent, More preferably, it is 5-20 weight%. Although alcohol, methanol, ethanol, n-propanol, isopropanol, n-butanol, etc. are mentioned, Methanol, ethanol, n-butanol, or a mixture thereof is used preferably.

In recent years, the solvent composition which does not use dichloromethane is also examined in order to minimize the effect on the environment. In this case, ethers having 4 to 12 carbon atoms, ketones having 3 to 12 carbon atoms, esters having 3 to 12 carbon atoms, and alcohols having 1 to 12 carbon atoms are preferable, and these may be mixed and used appropriately. For example, the mixed solvent of methyl acetate, acetone, ethanol and n-butanol is mentioned. These ethers, ketones, esters and alcohols may have a cyclic structure. Moreover, the compound which has two or more of functional groups of ether, ketone, ester, and alcohol (namely, -O-, -CO-, -COO-, and -OH) can also be used as a solvent.

About the detail of a cellulose acylate, it is described in Unexamined-Japanese-Patent No. 2005-104148-[0195], and these description can also be applied to this invention. In addition, additives such as solvents and plasticizers, antidegradants, ultraviolet absorbers (UV agents), optically anisotropic control agents, retardation control agents, dyes, matting agents, release agents, and release accelerators are similarly described in Japanese Patent Application Laid-Open No. 2005-104148. ], Are described in detail in paragraphs [0516], and these descriptions can also be applied to the present invention.

(Cyclic olefin)

The cyclic olefin is preferably polymerized from the norbornene-based compound. This polymerization can be performed by either of ring-opening polymerization and addition polymerization. As addition polymerization, it is a thing of description of Unexamined-Japanese-Patent No. 3517471, Unexamined-Japanese-Patent No. 3559360, Unexamined-Japanese-Patent 3867178, Unexamined-Japanese-Patent 3871721, Unexamined-Japanese-Patent 3907908, Unexamined-Japanese-Patent 3945598, Patent publication 2005-527696 The thing of Unexamined-Japanese-Patent No. 2006-28993, the international publication 2006/004376 pamphlet is mentioned. Especially preferred are those described in Japanese Patent No. 3517471.

Examples of the ring-opening polymerization include International Publication No. 98/14499, Japanese Patent 3060532, Japanese Patent 3220478, Japanese Patent 3273046, Japanese Patent 3404027, Japanese Patent 3428176, Japanese Patent 3687231, Japanese Patent 3873934 and the thing of Unexamined-Japanese-Patent No. 3912159 are mentioned. Among them, preferred are those described in International Publication No. 98/14499 Pamphlet and Japanese Patent No. 3060532.

It is more preferable that it is addition polymerization among these cyclic olefins.

(Lactone ring-containing polymer)

The thing which has a lactone ring structure represented by following General formula (1) is pointed out.

In General Formula 1, R ¹ , R ² and R ³ each independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms. In addition, the organic residue may contain the oxygen atom.

The content rate of the lactone ring structure of General formula (1) becomes like this. Preferably it is 5-90 weight%, More preferably, it is 10-70 weight%, More preferably, it is 10-50 weight%.

Polymer formed by polymerizing at least one selected from (meth) acrylic acid ester, hydroxyl group-containing monomer, unsaturated carboxylic acid, and monomer represented by the following (General Formula 2) in addition to the lactone ring structure represented by (General Formula 1). Structural units (repeated structural units) are preferred.

In formula (2), R ⁴ represents a hydrogen atom or a methyl group, X represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group, an —OAc group, a —CN group, a —CO—R ⁵ group, or —COR ⁶ group is represented, Ac group is an acetyl group, R <^5> and R <^6> represents a hydrogen atom or C1-C20 organic residue.

For example, international publication 2006/025445 pamphlet, Unexamined-Japanese-Patent No. 2007-70607, Unexamined-Japanese-Patent No. 2007-63541, Unexamined-Japanese-Patent No. 2006-171464, and Unexamined-Japanese-Patent No. 2005-162835 are described. Can be used.

[Example]

(Experiment 1)

In the tenter part 12 shown in FIG. 1, the extending | stretching process was performed to the film 20 of 80 micrometers in thickness, and 1600 mm in width, and the optical film 24 was obtained. The blowing head 52a and the suction head 65 shown in FIG. 6 were provided in the preheating area 36a. The blowing head 52b shown in FIG. 6 was provided in the extending area 36b. In the tenter part 12, the air adjusted to predetermined | prescribed temperature was sprayed with respect to the film 20. The temperature of the film 20 in the preheating area 36a is 150 ° C. The temperature of the film 20 in the stretching area 36b is 170 ° C. The temperature of the film 20 in the relaxation area 36c was 150 degreeC. Elongation (ER) in an extending | stretching process was 40%.

(Experiment 2)

The suction nozzle 65b was abbreviate | omitted. Omission means not used. Except this, it carried out similarly to Experiment 1, and the extending | stretching process was performed to the film 20 in the tenter part 12, and the optical film 24 was obtained.

(Experiment 3)

Blowing nozzle 60x was abbreviate | omitted. Except this, it carried out similarly to Experiment 1, and the extending | stretching process was performed to the film 20 in the tenter part 12, and the optical film 24 was obtained.

(Experiment 4)

The suction nozzle 65b and the jet nozzle 60x were abbreviate | omitted. In addition, after starting the tenter part 12, air was supplied to the stretching area 36b through the blowing head 52b, and then air was supplied to the preheating area 36a through the blowing head 52a. Except these, it carried out similarly to Experiment 1, and the extending | stretching process was performed to the film 20 in the tenter part 12, and the optical film 24 was obtained.

(Experiment 5)

The suction nozzle 65b and the jet nozzle 60x were abbreviate | omitted. Except this, it carried out similarly to Experiment 1, and extended | stretched the film 20 in the tenter part 12, and obtained the optical film.

Twenty sample films were equally cut out from the respective optical films obtained in Experiments 1 to 5 in the Y direction. And in-plane retardation Re and thickness direction retardation Rth of each sample film were measured. Next, ΔRe and ΔRth were calculated from the measured values of each retardation. And evaluation of the presence or absence of an optical deviation was made based on the following references | standards using this (DELTA) Re and (DELTA) Rth as an index.

(Evaluation of ΔRe)

A: ΔRe is within 4 nm.

B: ΔRe is greater than 4 nm and is within 8 nm.

C: ΔRe is greater than 8 nm and is within 10 nm.

D: ΔRe is greater than 10 nm.

(Evaluation of ΔRth)

A: ΔRth is within 4 nm.

B: ΔRth is larger than 4 nm and is within 8 nm.

C: ΔRth is larger than 8 nm and within 10 nm.

D: ΔRth is greater than 10 nm.

Table 1 shows the presence or absence of the jet nozzle 60x in experiments 1 to 5, the presence or absence of the suction nozzle 65b, the air flow direction at the boundary between the preheating area 36a and the stretching area 36b, and ΔRe. And the evaluation result of the presence or absence of the optical deviation using? Rth as an index. In the "air flow direction" column of Table 1, the flow direction of the air in the boundary of the preheating area 36a and the extending | stretching area 36b was the direction which goes to the preheating area 36a from the extending area 36b. The case was shown as "A" and the case where it was a direction toward the extending | stretching area 36b from the preheating area 36a was shown as "B".

Table 1 shows that according to the present invention, the stretching treatment can be performed while suppressing the occurrence of the optical deviation failure.

Claims (12)

A traveling portion for traveling a thermoplastic resin film, comprising: a traveling portion sequentially passing through a preheating area and a drawing area provided with the thermoplastic resin film inside the tenter by traveling by the traveling portion;
A first hot air supply unit for injecting a first hot air into the thermoplastic resin film traveling through the preheating area, the first hot air supply unit having a higher temperature than the tenter outside air in which the first hot air is outside the tenter;
A second hot air supply unit for injecting a second hot air into the thermoplastic resin film traveling through the stretching area, wherein the second hot air supply unit has a temperature higher than a temperature of the first hot air;
A stretching portion for stretching the thermoplastic resin film traveling on the stretching area, the stretching portion for stretching the thermoplastic resin film in a direction orthogonal to the traveling direction; And
A direction adjusting unit that adjusts a direction in which the second hot air flows at the boundary between the preheating area and the stretching area, wherein a direction in which the second hot air flows at the boundary flows from the stretching area by the direction adjusting unit. A stretching apparatus for a thermoplastic resin film, comprising a direction adjusting portion that is set in a direction toward the preheating area. The said direction adjusting part has a blowing nozzle provided in the said drawing area, The said blowing nozzle is formed so that it may extend toward the said boundary, The blowing opening which blows out the said 2nd hot air is the front-end | tip of the said blowing nozzle. A stretching apparatus for a thermoplastic resin film, characterized in that formed on. The said direction adjusting part has a suction nozzle provided in the said preheating area, The said suction nozzle is formed so that it may extend toward the said boundary, The suction port which suctions the said 2nd hot air is a thing of the said suction nozzle. An apparatus for stretching a thermoplastic resin film, which is formed at the tip. 3. The stretching device of a thermoplastic resin film according to claim 2, wherein the jet port has a slit shape and is elongated in the stretching direction. 4. The stretching apparatus for a thermoplastic resin film according to claim 3, wherein the suction port has a slit shape and is elongated in the stretching direction. A step of injecting the first hot air into the thermoplastic resin film traveling on the preheating area, wherein the first hot air is higher in temperature than the tenter outside air outside the tenter, and the preheating area is formed inside the tenter. ;
A step of injecting a second hot air into the thermoplastic resin film traveling in the stretching area to stretch the thermoplastic resin film in a direction orthogonal to the traveling direction, wherein the second hot air is a temperature equal to or higher than the temperature of the first hot air. A step in which said drawing area is formed inside said tenter and is located downstream of said running direction than said preheating area; And
A step of adjusting a direction in which the second hot air flows at the boundary between the preheating area and the stretched area, wherein a direction in which the second hot air at the boundary flows by the adjustment is preheated from the stretch area. The manufacturing method of the optical film characterized by including the step which becomes the direction which goes to an area. 7. The method of manufacturing the optical film according to claim 6, wherein in the direction adjusting step, the second hot air is sent from the downstream side in the traveling direction toward the boundary. The manufacturing method of an optical film according to claim 6, wherein in the direction adjusting step, the second hot air is sucked upstream of the traveling direction from the boundary. The said 2nd hot air is made to flow at a uniform flow volume in the said extending direction, The manufacturing method of the optical film of Claim 6 characterized by the above-mentioned. The method of manufacturing an optical film according to claim 7, wherein the thermoplastic resin film is produced by a solution film forming method. 8. The method of claim 7, wherein the thermoplastic resin contains cellulose acylate. 8. The method of claim 7, wherein the thermoplastic resin contains a cyclic polyolefin.

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