KR20110109982A - Solution film forming method - Google Patents

Abstract

The casting film 32 is heated by the first to third ducts 36 to 38 to advance drying. The heating of the casting film 32 which started temperature-falling once by this heating is cooled through the band 29 by the 2nd roller 28, and is maintained in a fixed temperature range. This temperature maintenance is continued by the third duct 38. The flexible film 32 which reached the 4th position P4 is cooled through the band 29 by the 1st roller 27. As shown in FIG. This cooling is performed so that the flexible film 32 hardens without crystallization of the polymer. The flexible film 32 is peeled from the band 29, maintaining the temperature reached by cooling. The wet film which peeled is dried by a tenter and a roller drying apparatus, and it is set as the film 23.

Description

SOLUTION FILM FORMING METHOD

The present invention relates to a solution film forming method for producing a polymer film for polarizing plate use.

As a polymer film used for optical uses, such as a display apparatus, a cellulose acylate film, a cyclic polyolefin film, etc. are mentioned. As a manufacturing method of such a polymer film, there exists a solution film forming method. The solution film forming method is a manufacturing method in which a dope in which a polymer is dissolved in a solvent is cast on a support to form a cast film, the cast film is hardened and peeled off, and the peeled cast film, that is, the wet film, is dried to form a polymer film. This solution film has a dry casting method and a cooling gelation casting method, as known by the method of hardening the casting film.

As is well known in the drying casting method, the casting film is dried to a desired drying level, and the casting film is hardened by this drying. That is, after peeling, a casting film is dried and hardened to the extent that a wet film can be conveyed.

On the other hand, as it is well known, the cooling gelation casting method is to form a gel by cooling the casting film and to advance the gelation until it is hard enough to be transported even if peeled off.

There is also a method of cooling the flexible membrane immediately before peeling, based on a dry casting method. Such a method is described in, for example, Japanese Patent Laid-Open No. 2006-306059. In this Japanese Patent Laid-Open No. 2006-306059 method, the casting membrane is cooled by injection of a cooling wind so as to be 6 ° C or lower immediately before peeling. According to this method, a film without blur can be efficiently produced.

In addition, Japanese Patent Laid-Open No. 11-058425 performs a two-step drying process by using a dry casting method. The two-step drying step is a step of drying the drying air until reaching a preset gelation temperature and a step of drying it to dry faster after reaching the gelation temperature. Thereby, thickness variation of a polymer film can be made small.

Moreover, there is patent 4169183 as a manufacturing method of the long polymer film which passed through the process extended to the width direction. In this method, manufacturing efficiency is improved by performing an extending | stretching process in the width direction at a faster timing than before in the solution film forming process.

By the way, the polymer film is cut | disconnected and used for the dimension according to a use. Although cutting may consist only of a polymer film before combining with the member to combine, it may be made with the member after combining with the member to be combined. For example, when manufacturing a polarizing plate, it cuts after bonding a polarizing film and the polymer film used as a protective film which protects this. Moreover, also when replacing one of a pair of protective film arrange | positioned on both surfaces of a polarizing film with an optical compensation film (including a phase difference film), it is the same. That is, an optical compensation film may be used as a protective film.

When cut | disconnecting to a desired dimension in order to set it as a polarizing plate from the film of the multilayer structure which bonds a polarizing film and a protective film, a cutting blade is pressed and cut | disconnected from one film surface with respect to a multilayer structure film. Thus, when a multilayer structure film is cut | disconnected, a crack may arise in the inside of a protective film from the cut surface formed by cutting | disconnection. Evaluation that a protective film which a crack generate | occur | produces in this way by cutting is bad is performed, and the commodity value may fall remarkably also about the polarizing plate obtained.

Moreover, when manufacturing a liquid crystal display, a polarizing plate is stuck to a glass substrate. When the bonding state does not become a desired state at the time of this bonding, what is called a rework which peels a polarizing plate from a glass substrate once, and bonds again is performed. In the protective film of a polarizing plate, a part of protective film may remain on a glass substrate at the time of peeling which peels especially from a glass substrate among these rework. Thus, the protection film which the whole does not peel and a part remains on a glass substrate is evaluated that reworkability is bad, and it is unpreferable.

When comparing the dry casting method and the cooling gelation casting method, the latter is remarkably superior in terms of production efficiency. However, the polymer film obtained by the cooling gelation casting method is inferior to the polymer film obtained by the drying casting method in view of the above processability and reworkability.

As described above, the dry casting method and the cooling gelling casting method are difficult to cover the superiority from different viewpoints, and the phenomenon is selected based on various performances desired according to the use of the polymer film.

However, even when using the methods of JP 2006-306059, JP 11-058425 and JP 4169183, the manufacturing efficiency and the reworkability of the level of the manufacturing efficiency and the level of the drying flexibility of the cooling gelation casting method are the same. Incompatibility is not compatible.

An object of the present invention is to provide a method for forming a solution in which a polymer film having a processability and reworkability level of a film made by a dry casting method can be produced at a production efficiency in a cooling gelation casting method.

In order to solve the above problems, the solution film forming method of the present invention includes a casting step (A step), a casting film drying step (B step), a heating temperature holding step (C step), a cooling step (D step), and a peeling step (E step). And a film drying step (F step). In step A, the dope in which the polymer is dissolved in the solvent is cast on the support to form a cast film. Step B heats the cast film to advance drying. C step maintains the said flexible film | membrane which started heating up after temperature-falling once in said B step in fixed temperature range. Step D cools the flexible film so that the flexible film is hardened without crystallization of the polymer in the flexible film after the C step. E step peels from the said support body as the wet film of the state containing the solvent, maintaining the temperature reached by the said cooling. The F step dries the wet film.

In this solution film-forming method, the temperature of the said flexible film is controlled through the said support body by adjusting the circumferential surface temperature, and the said stepless endless support body which contact | connects the circumferential surface by the roller pair which rotates in the circumferential direction is conveyed, and said A It is preferable to cast the said dope about the 1st winding area | region wound by the said one roller of the said support body in a step. The step B starts with respect to the flexible film facing the other roller, and the step C maintains the temperature of the flexible film by the other roller through the second winding region of the support wound around the other roller. It is desirable to. It is preferable that the said D step cools the said flexible film | membrane with the said one roller, and the said E step peels the said flexible film | membrane from the said 1st winding area | region.

When the gelation point of the flexible membrane is TG, it is preferable to cool the flexible membrane to a temperature range of TG or more and TG + 20 ° C in step D.

It is preferable that the said C step maintains the temperature of the said flexible film until the residual ratio of the said solvent in the said flexible film becomes 100 mass%.

It is preferable to make time from the start of temperature rise in the said B step to the said end of said C step into the range of 10 second or more and 100 second or less.

As for the solution film forming method, it is more preferable to provide a cooling temperature maintenance step (G step). G-step maintains the said flexible film which started to fall by cooling in the said D step in a fixed temperature range before the said E-step. Here, the time from the start of the temperature drop by the cooling to the end of the G step is in the range of 1 second to 30 seconds.

It is preferable that the dope is irradiated with respect to the said flexible film, and the dope hardening material hardened | cured by the irradiation of a live line is previously included in the said dope.

It is preferable that the live wire is irradiated to the flexible film after the C step is started.

It is preferable to continuously cast the said dope in the said A step, and to peel a casting film as follows. It arrange | positions so that the longitudinal direction may correspond to the width direction of the said support body flexible surface, and winds up the said wet film in the circumferential surface of the peeling roller provided in the opposite side to the said support about the conveyance path of the said wet film, and conveys the said wet film. The said flexible film is peeled off by this. When the space on one film surface peeled from the said support body of the said wet film is made into a 1st space, and the space on the other film surface is made into a 2nd space, the conveyance path of the said wet film toward the said peeling roller becomes the said 1st space. The pressure of the second space upstream of the separation roller is made smaller than the pressure of the first space so as to be convex toward the two spaces.

It is preferable to suck the gas of the said 2nd space upstream from the said peeling roller by the suction apparatus which sucks a gas, and to decompress the said 2nd space between the said peeling position from which the said flexible film peels from the said peeling roller and the said support body. .

It is preferable that the said suction device is provided with the chamber which partitions the said 2nd space to be decompressed with an external space, and controls the path | route of conveyance of the said wet film toward the said peeling roller by adjusting the pressure in the said chamber.

According to this invention, the polymer film which has the processability and the rework property level of the film made by the dry casting method can be manufactured by the manufacturing efficiency in a cooling gelation casting method.

The above objects and advantages will be readily understood by those skilled in the art by reading the detailed description of the preferred embodiments with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS The schematic diagram of the solution film forming installation which implemented this invention.
2 is a schematic view of a wet film forming apparatus.
3 is a graph showing the temperature change of the flexible membrane.
4 is a schematic diagram of a path controller.
5 is a schematic diagram of a path controller.

The solution film forming equipment 10 of FIG. 1 has a wet film forming apparatus 17, a tenter 18, a roller drying apparatus 22, and a winding apparatus 24. The wet film forming apparatus 17 forms the wet film 16 from the dope 13 in which the polymer 11 is dissolved in the solvent 12. The tenter 18 advances drying, applying the tension to the formed wet film 16 to the width direction suitably. The roller drying apparatus 22 further advances drying, carrying the wet film 16 which passed through the tenter 18 with the roller 21, and makes it the film 23. As shown in FIG. The winding device 24 winds up the dried film 23 in roll shape. In addition, the solution film forming equipment 10 includes the wet film 16 and the film 23 on each conveying path between the tenter 18 and the roller drying device 22 and between the roller drying device 22 and the winding device 24. A slit device (not shown) which cuts off each side end part is provided.

The wet film forming apparatus 17 includes a first roller 27 and a second roller 28 that rotate in the circumferential direction. The band 29 as an endless flexible support body is wound around the first roller 27 and the second roller 28. At least one of the 1st roller 27 and the 2nd roller 28 should just be a drive roller which has a drive means. At least one of the roller pairs which consists of this 1st roller 27 and the 2nd roller 28 rotates in a circumferential direction, and the band 29 which contact | connects a circumferential surface is conveyed. Above the band 29, a flexible die 31 for flowing out the dope 13 is provided. By continuously flowing the dope 13 from the casting die 31 to the band 29 being conveyed, the dope 13 is cast on the band 29 to form the casting film 32. Moreover, although the pressure reduction chamber is provided upstream in the running direction of the band 29 with respect to the dope 13 which reaches the band 29 from the die 31, illustration is abbreviate | omitted. This pressure reduction chamber sucks in the atmosphere of the upstream area of the dope 13 which flowed out, and reduces the said area.

The flexible film 32 is hardened to the extent that it can be conveyed by the tenter 18, and then peeled from the band 29 in a state containing a solvent. At the time of peeling, the wet film 16 is supported by a peeling roller (hereinafter referred to as a peeling roller) 33 so that the peeling position PP at which the flexible film 32 is peeled from the band 29 (see FIG. 2) is fixed. Keep it.

The wet film forming apparatus 17 is provided with the first duct 36, the second duct 37, and the third duct 38 in order from the upstream side along the running path of the band 29. The first duct 36, the second duct 37, and the third duct 38 send the dried gas toward the flexible membrane 32. However, the number of ducts is not limited to three. The first to third ducts 36 to 38 will be described later using other drawings.

Downstream of the third duct 38 is a light source 45 that emits live lines.

On the upstream side of the peeling roller 33, the path control part 46 which controls the path | route of the wet film 16 toward the peeling roller 33 is provided.

The method of hardening and peeling the flexible film 32 is mentioned later using different drawings, respectively.

In the movement from the film forming apparatus 17 to the tenter 18, a plurality of rollers 48 are provided. The wet film 16 formed by the peeling is conveyed by these rollers 48 and guided to the tenter 18. In the tenter 18, the side end part of the wet film 16 is supported by a support means (not shown), and the wet film 16 is dried while conveying to this support means. The support means displaces the wet film 16 in the width direction at the predetermined position in the conveying direction so as to apply the predetermined tension in the width direction at a predetermined timing.

The tenter 18 is formed as a chamber surrounding the conveying path. A duct (not shown) is provided inside the tenter 18, and an air supply nozzle (not shown) and a suction nozzle (not shown) are opposed to a conveying path of the wet film 16 in the duct (not shown). Are each formed in plurality. The inside of the tenter 18 is maintained at a constant humidity and solvent gas concentration by the delivery of the dry gas from the air supply nozzle and the suction of the gas from the suction nozzle. The wet film 16 is dried by passing the inside of the tenter 18.

The wet film 16 which has passed through the tenter 18 is removed by slit device (not shown) by continuously cutting each side end portion with supporting marks by the support means with a cutting blade. The center part between one side end part and the other side end part is sent to the roller drying apparatus 22.

When the wet film 16 is sent from the tenter 18 to the roller drying apparatus 22, it is supported by the circumferential surface of the plurality of rollers 21 arranged side by side in the conveying direction. Among these rollers 21, there is a driving roller that rotates in the circumferential direction and is conveyed by the rotation of the driving roller.

The roller drying apparatus 22 is provided with the duct (not shown) which flows out the dried gas. The roller drying apparatus 22 is formed as a chamber which partitions the space into which the drying gas is fed from the outside. The exhaust port is formed in the roller drying apparatus 22. The interior of the roller drying apparatus 22 is maintained at a constant humidity and solvent gas concentration by the delivery of the drying gas from the duct and the exhaust from the exhaust port. By passing the inside of this roller drying apparatus 22, the wet film 16 is dried and it becomes the film 23. As shown in FIG.

The film 23 dried by the roller drying apparatus 22 is removed by continuously cutting each side end portion with a cutting blade in a slit apparatus (not shown). The center part between one side end part and the other side end part is sent to the winding-up apparatus 24, and wound up in roll shape.

The process from casting | flow_spread to peeling is demonstrated more concretely. As shown in FIG. 2, the band 29 spans the first roller 27 and the second roller 28. The position falling from the 1st roller 27 by moving the band 29 wound by the 1st roller 27 is made into 1st position P1. The position where the band 29 toward the 2nd roller 28 from the 1st position P1 starts to contact a 2nd roller is made into the 2nd position P2. The position where the band 29 wound by the 2nd roller 28 falls from the 2nd roller 28 is made into the 3rd position P3. The position where the band 29 which faces the 1st roller 27 from 3rd position P3 starts to contact the 1st roller 27 is made into the 4th position P4. The position where the dope 13 is flexible is set to flexible position PC. The position at which the flexible film 32 is peeled off is referred to as the peeling position PP. In addition, in FIG. 2, the illustration of the path controller 46 is omitted to avoid the complexity of the drawing.

The area | region wound by the 1st roller 27 among the band 29 is called the 1st area | region, and the area | region wound by the 2nd roller 28 is called 2nd area | region. That is, the first area is an area that reaches the first position P1 from the fourth position P4, and the second area is an area that reaches the third position P3 from the second position P2.

A plurality of outlets 36a, 37a, 38a for allowing the dried gas to flow out are formed in the first to third ducts 36 to 38, respectively, facing the traveling path of the band 29. Each outlet 36a, 37a, 38a becomes the slit shape extended in the width direction of the band 29. As shown in FIG. However, the shapes of the outlets 36a, 37a, and 38a are not limited to this.

The first to third ducts 36 to 38 are respectively connected to the blower 41, and the gas supplied from the blower 41 flows out from the outlets 36a, 37a, and 38a. The blower 41 is connected to the blower 41 which independently controls the temperature, humidity, and flow volume of the gas supplied to each of the 1st duct-the 3rd duct 36-38. Drying of the flexible film 32 toward 4th position P4 is advanced by the outflow of the gas by the 1st duct-the 3rd duct 36-38. Thus, a flexible film drying process is performed by the drying means which consists of the 1st-3rd ducts 36-38, the blower 41, and the blower controller 42. As shown in FIG. The casting film drying process is disclosed with respect to the casting film 32 facing the second roller 28.

The flow of gas from the first to third ducts 36 to 38 is heated wind, that is, warm air. The flexible film 32 is heated by this warm air. The temperature of the flexible film 32 is adjusted by control of the temperature and flow rate of this warm air, and temperature control mentioned later of the 1st roller 27 and the 2nd roller 28. As shown in FIG.

The first roller 27 and the second roller 28 are provided with a first controller 51 and a second controller 52 for controlling the circumferential surface temperature to a predetermined temperature, respectively. The first temperature detecting means 53 and the second temperature detecting means 54 are provided near the running path of the band 29. The first temperature detecting means 53 detects the temperature of the flexible film 32 at the fourth position P4. The second temperature detecting means 54 detects (detects) the temperature of the flexible film 32 at the second position.

When the temperature of the flexible film 32 is detected (detected) by the first temperature detecting means 53, the circumferential surface temperature of the first roller 27 is set based on this detection result (detection signal). When a signal corresponding to the set temperature is input to the first controller 51, the first controller 51 adjusts the circumferential surface temperature of the first roller 27. The first roller 27 controls the temperature of the flexible film 32 reaching the peeling position PP from the fourth position P4 via the band 29.

Similarly, when the temperature of the flexible film 32 is detected (detected) by the second temperature detecting means 54, the circumferential surface temperature of the second roller 28 is set based on this detection result (detection signal). When a signal corresponding to the set temperature is input to the second controller 52, the second controller 52 adjusts the circumferential surface temperature of the second roller 28. The second roller 28 controls the temperature of the flexible film 32 reaching the fourth position P4 from the second position P2 through the band 29.

As mentioned above, the flexible film 32 which faces the 2nd position P2 is controlled by the gas from the 1st duct 36 to desired temperature (temperature aimed). Moreover, the flexible film 32 which faces the 4th position P4 from the 2nd position P2 is made into the desired temperature by the gas from the 2nd duct 37 and the 3rd duct 38, and the 2nd roller 28. Controlled. In addition, the flexible film 32 which faces the peeling position PP from 4th position P4 is controlled by the 1st roller 27 to desired temperature. 2, the flexible position PC is made upstream than the 1st position P1. However, the flexible position PC may coincide with the first position P1. Thus, the flexible position PC should just be downstream from the peeling position PP in the 1st area | region of the band 29. FIG.

In order to implement a casting film drying process, in this embodiment, the drying means containing the 1st-3rd ducts 36-38 is used. However, the drying means is not limited to this, and other drying means may be used depending on the properties of the cast film 32 and its change over time. As another drying means, there exists a drying means including a condenser, for example, You may use or add this instead of the drying means containing the 1st-3rd ducts 36-38.

The condenser has a cooling unit which can be controlled at a predetermined temperature. The condenser is disposed in place of the first to third ducts 36 to 38 so that the cooling unit faces the flexible membrane 32. By setting the cooling section at a temperature lower than the atmosphere around the casting film 32, the solvent 12 evaporated from the casting film 32 is condensed in the cooling section to become a liquid. Since the concentration of the solvent gas in the atmosphere is maintained in a certain range by condensation, drying of the casting film 32 proceeds. Drying by the condenser is superior in maintaining smoothness of the exposed surface of the flexible membrane 32 than injecting gas. Therefore, the flexible membrane 32 may be dried using a condenser until reaching a constant dry state, and may be changed to drying by injection of gas when reaching the constant dry state. Moreover, about the running path of the band 29, you may provide the heater which heats the band 29 in the area opposite to a condenser. In the area opposite to the condenser, the condenser is provided so as to face the non-flexible surface on the opposite side to the flexible surface on which the flexible membrane 32 of the band 29 is formed. When a heater is provided in this way, drying of the flexible film 32 advances faster, and the 1st temperature-fall and 1st temperature rising temperature mentioned later generate more reliably.

In FIG. 3, the vertical axis | shaft is temperature of the casting film 32, and the horizontal axis is time. In the graph of FIG. 3, "PC", "P1", "P2", "P3", "P4", and "PP" are the flexible position PC, the first position P1, the second position P2, and the first. It shows that it is the temperature in 3 position P3, 4th position P4, and peeling position PP, respectively. Moreover, in the horizontal axis | shaft of FIG. 3, the time which reaches the 3rd position P3 from the 2nd position P2, and the time which reaches the 1st position P1 from the 4th position P4 is made from the 1st position P1. It is greatly exaggerated about the time to 2nd position P2, and the time to reach 4th position P4 from 3rd position P3.

As shown in FIG. 3, the temperature of the flexible film 32 in the 1st position P1 is very high compared with the subsequent flexible film 32. As shown in FIG. This is because if the temperature of the dope 13 is too low, the fluidity is too low to be flexible, and thus the desired flexible film 32 cannot be formed. Therefore, the temperature of the casting film 32 in the 1st position P1 is substantially the same as the temperature of the dope 13 to be cast.

When the polymer 11 is cellulose acylate and the concentration of solid components such as cellulose acylate in the dope 13 is in the range of 15% by mass to 35% by mass, the temperature of the dope during casting is 20 ° C or more. It is preferable to set it as the range of 40 degrees C or less. However, this temperature range changes somewhat depending on the traveling speed of the band 29 to the manufacturing speed of the film 23. Said temperature range is a case where the manufacturing speed of the film 23 is 10 m / min or more and 120 m / min or less.

As the drying film proceeds, the flexible film 32 facing the second position P2 begins to rise and then rise in temperature. The temperature drop and the temperature increase are the heat entering the flexible membrane 32 from the atmosphere around the flexible membrane 32 mixed with the gas from the first duct 36 and the latent heat of evaporation of the solvent 12 (see FIG. 1) from the flexible membrane 32. It is by so-called heat balance of family. In other words, when the latent heat of evaporation is greater than the heat entering the flexible membrane 32 from the atmosphere, the flexible membrane 32 is lowered, and when it is small, the flexible membrane 32 is heated up.

Since the evaporation amount of the solvent is large for a predetermined period after the casting film 32 is formed, the latent heat of evaporation is greater than that from the atmosphere, so that the casting film 32 is cooled. The amount of evaporation per unit time of the solvent gradually decreases after that, and then the temperature starts to rise because the heat from the atmosphere becomes larger than the latent heat of evaporation. As described above, in the present invention, the temperature is lowered once (hereinafter referred to as the first temperature lower temperature) and the temperature increased after the temperature is lowered (hereinafter referred to as the first temperature increase) by using the thermal history of the temperature drop and the temperature rise by the heat balance between the latent heat of evaporation and the heat from the atmosphere. Wait).

By passing through the first elevated temperature, the direction of the molecules of the polymer 11 can be made more random.

The polymer 11 is a cellulose acylate, the density | concentration of solid components, such as the cellulose acylate in the dope 13, is 15 mass% or more and 35 mass% or less, and the component with the highest evaporation rate in the solvent 12 When the boiling point is 40 ° C. or more and 100 ° C. or less, the temperature attained at the first temperature is in the range of 5 ° C. or more and 30 ° C. or less. However, this temperature range changes somewhat depending on the temperature of the gas from the first duct 36 and the flow rate of the gas from the first duct 36. Said temperature range is a case where the temperature of the gas from the 1st duct 36 is 10 degreeC or more and 120 degrees C or less, and the flow volume is 10 m <^3> / min or more and 250 m <^3> / min or less.

In consideration of the timing of each step to be performed below, it is preferable to express the first temperature drop and the first temperature increase of the flexible membrane 32 in the flexible membrane 32 before reaching the second position P2. That is, when the band 29 is repeatedly circulated by the roller pair composed of the first roller 27 and the second roller 28, the first roller 27 to the second roller 28, and The path lengths of the bands 29 from the second roller 28 to the first roller 27 are the same, and in this case, the first temperature drop and the first temperature are applied to the flexible film 32 facing the second position P2. It is preferable to generate 1 temperature rise.

In order to more reliably express the first temperature and the first elevated temperature in the flexible membrane 32 facing the second position P2, the temperature and flow rate of the gas from the first duct 36 and the solvent in the dope 13 What is necessary is just to adjust these ratios, the temperature at the time of the casting of the dope 13, and the distance of the 1st duct 36 and the band 29, and to balance these.

When cellulose acylate is used as the polymer 11, the temperature of the gas from the first duct 36 is 10 ° C or more and 120 ° C or less, and the flow rate is 10m ³ / minute or more and 200m ³ / minute or less and in the dope 13 The mass ratio with respect to cellulose acylate of the solvent with the largest evaporation rate among the solvents is 200% or more and 550% or less, and the temperature at the time of casting of dope 13 is 20 degreeC or more and 40 degrees C or less, 1st duct and a band ( 29), it is preferable to set the distance to each range of 10 mm or more and 200 mm or less. Moreover, such a value is a case where the thickness of the film 23 to manufacture is 20-80 micrometers.

When the temperature reaches a constant temperature by the first temperature drop, there is a case where the first temperature rise starts immediately, and the first temperature rise starts after the constant temperature is maintained. This difference is due to the type and combination of the solvent 12 and the temperature and flow rate of the gas from the first duct 36. It is more preferable that the first temperature rise starts after the constant temperature is maintained rather than the first temperature rise starts immediately. This is because evaporation of the solvent does not occur abruptly and the foaming of the cast film 32 can be prevented more reliably than the above temperature is maintained. Therefore, it is more preferable to adjust the temperature and flow rate of the gas from the first duct 36 so as to maintain the temperature of the flexible membrane 32 for a predetermined time at the temperature reached by the first lower temperature before the first elevated temperature starts.

In the case where the temperature of the flexible film 32 is maintained for a predetermined time at the temperature reached by the first drop in temperature, the time t1 from the start of the first drop in temperature to the end of temperature holding corresponding to the start of the temperature increase is 5 seconds or more and 100 seconds or less. It is preferable to set it as the range of.

When the temperature rises in the section reaching the second position P2 from the first position P1, the flexible membrane 32 often continues to increase the temperature due to the outflow of gas from the first duct 36. The flexible film 32 may foam when it exceeds a fixed temperature. Therefore, the temperature of the flexible film 32 is maintained in a fixed range so as not to exceed the fixed temperature. This process is called heating temperature maintenance process.

By performing a heating temperature maintenance process, the effect of suppression of the surface orientation by the cooling process and the peeling process which are subsequent processes can be reliably obtained.

The heating temperature maintaining step is performed by at least one of the second roller 28 and the second duct 37. In addition, the temperature of the flexible film 32 to the second position P2 is not excessively raised so that foaming or the like does not occur before reaching the second roller 28. It is preferable to control the temperature and the flow rate of the gas from the first duct 36 so as to suppress this temperature rise.

While reaching the third position P3 from the second position P2, the temperature of the flexible membrane 32 is maintained in a constant range while the drying of the flexible membrane 32 is performed. Therefore, at least one of the outflow conditions of the gas from the 2nd duct 37 and the circumferential surface temperature of the 2nd roller 28 is controlled, and the balance of drying of the casting film 32 and temperature adjustment is aimed at.

For example, in the case where the flexible membrane 32 is kept in a lower temperature range, in order to suppress the decrease in the drying rate, the temperature of the gas is lowered or the second temperature is not reduced without lowering the flow rate of the gas from the second duct 37. What is necessary is just to make lower the peripheral surface temperature of the roller 28.

In the heating temperature maintaining step, it is more preferable to keep the temperature of the flexible film 32 constant. This is because improvement in the thickness variation (uniformity of the thickness) of the flexible film 32 due to the leveling effect and improvement in the optical variation, processing aptitude, and reworkability due to the randomization of the direction of the polymer 11 are achieved more reliably.

When the polymer is cellulose acylate, the flexible film 32 in the heating temperature maintaining step is in the range of 5 ° C or more and 40 ° C or less, more preferably in the range of 10 ° C or more and 40 ° C or less, still more preferably 15 ° C or more 40 It is preferable to maintain in the range below ° C. Particularly preferably, the temperature of the flexible film 32 is set within a range of 10 ° C within 10 seconds to 100 seconds in the above range.

It is preferable to perform a heating temperature maintenance process until the solvent residual ratio of the cast film 32 becomes 200 mass%. The heating temperature holding step is more preferably performed until it is 150% by mass, still more preferably until it is 100% by mass. As a result, the thickness of the flexible film 32 becomes more uniform, and the effect of suppressing the optical deviation, the processing aptitude, and the rework property are more reliably achieved.

Therefore, it is preferable to continue heating temperature maintenance process also about the flexible film 32 which passed 3rd position P3. What is necessary is just to perform a heating temperature maintenance process by the 3rd duct 38 downstream from 3rd position P3.

It is preferable to make time (t2) from the 1st temperature start start until the completion | finish of a heating temperature maintenance process into the range of 10 second or more and 100 second or less. When it is 10 seconds or more, the uniformity of the thickness of the flexible film 32 and the optical deviation, processing aptitude, and rework property of the film 23 are further improved, compared with the case of less than 10 seconds. Moreover, even if it is longer than 100 second, since the direction of the molecule | numerator of the polymer 11 is already fully randomized, said effect is not improved more. If it is longer than 100 seconds, the manufacturing efficiency of the film 23 may be lowered or the length of the solution forming facility 10 may be increased. However, this time varies slightly depending on the traveling speed of the band 29 to the manufacturing speed of the film 23 and the thickness of the cast film 32. The said time range is a case where the manufacturing speed of the film 23 is 15 m / min or more and 100 mm / min or less, and the thickness of the cast film 32 is 20 micrometers or more and 80 micrometers or less.

It is preferable to include the live hardening material in the dope 13 beforehand. A live hardening material is a material hardened | cured by irradiating a live wire. The dope 13 may form at least one of these multilayers, when the flexible film 32 is a multilayer structure. In this case, the light source 45 is provided in the vicinity of the traveling path of the band 29 so that the flexible film 32 can face the passage. In this embodiment, since the photocurable material hardened | cured by irradiation of light, such as an ultraviolet-ray (UV), is used as a live-curing material, the light source 45 was used as a lively irradiation means. As an active hardening material, there exists a thermosetting material hardened | cured by giving heat, and the ultraviolet-ray hardened material hardened | cured by irradiating an ultraviolet-ray (UV). The live irradiation means is selected according to the type of these live hardened materials.

In this embodiment, the 3rd duct 38 is arrange | positioned so that the downstream end of the 3rd duct 38 may be upstream than 4th position P4, and a live-irradiation is carried out with respect to the flexible film 32 after a flexible film drying process and before a cooling process. Is being carried out. In addition, the live-irradiation in this embodiment is performed during the heating temperature maintenance process. Instead of this aspect, you may implement about the casting film 32 in a casting film drying process. However, it is especially preferable to perform live irradiation at the timing after the start of a heating temperature maintenance process. This is because the polymer molecules in the flexible film 32 are more stable than before the start of the heating temperature maintaining step. From this point of view, it is more preferable to perform live irradiation after the heating temperature maintenance step is performed for a predetermined time or after the completion.

After the heating temperature maintaining step, the cooling step is performed. The cooling step is a step of lowering the temperature by cooling the flexible membrane. When performing live irradiation after a heating temperature maintenance process, this live irradiation may be performed before or after a cooling process. More preferably, it is performed before a cooling process.

A cooling process is a process of cooling this so that the casting film 32 may harden without crystallization of the polymer in the casting film 32. If the crystallization did not start before the start of the cooling process, it is cooled so that crystallization does not occur. If the crystallization is already started before the start of the cooling process, it is cooled so that the crystallinity does not increase.

The surface orientation of the polymer in the wet film 16 at the time of peeling and after peeling is suppressed by this cooling process and the peeling process mentioned later. The processing aptitude and reworkability of the film 23 obtained by suppressing the plane orientation are equivalent to or higher than those of the film obtained by the conventional dry casting method. Moreover, by combining this cooling process and the peeling process mentioned later with the above-mentioned flexible film drying process and heating temperature maintenance process, manufacturing efficiency becomes it is the same as or more than the conventional cooling flexible system. Moreover, surface orientation means oriented along a film surface. By suppressing the plane orientation as in the present invention, the film 23 in which the polymer molecules are entangled more uniformly in the thickness direction can be produced, so that the processing aptitude and the rework property are further improved.

The temperature of the flexible film 32 which hardens so that crystallization of a polymer does not advance is based on the kind of the polymer 11 and the solvent 12, and the solvent residual ratio of the flexible film 32 at the time of cooling. Therefore, the temperature of the flexible film 32 which should be reached in a cooling process is set based on the kind of the polymer 11 and the solvent 12, and the solvent residual ratio of the flexible film 32. Therefore, for each combination of the polymer 11 and the solvent 12 to be used, for example, the relationship between the crystallinity, the solvent residual ratio and the temperature may be determined in advance, and the temperature may be set based on the obtained relationship.

Crystallinity can be obtained by various known methods. For example, thermal analysis using a differential scanning calorimetry (DSC) measuring device, or analysis by infrared (IR) spectrum. Instead of the degree of crystallinity, another factor having a constant relationship with crystallization may be used to determine the relationship between the factor and the temperature in advance to set the temperature of the flexible film 32 to be reached in the cooling step.

As a method of setting the temperature of the flexible membrane 32 to be reached in the cooling process with certainty and simpler as in the above method, the gelation temperature TG (° C.) of the flexible membrane 32 is obtained in advance, and the flexible membrane 32 is obtained. What is necessary is just to cool so that it may become in the range below TG (TG + 20 degreeC) or less.

About the gelation temperature TG, P1 = a x 1n (b / T) expression when the dope 13 has a temperature T <TG between the viscosity P and the absolute temperature T, and P2 when the T> TG. When approximated by the formula of c = 1n (d / T), this polymer solution has a gelation point, and the change point TG is defined as the gelation temperature (a, b, c, d. Is an experimentally determined constant).

In the case where the polymer is cellulose acylate and the solvent residual ratio at the start of the cooling step is in the range of 100% by mass or more and 200% by mass or less, the gelation temperature (TG) is in the range of -10 ° C or more and 20 ° C or less. In addition, in this specification, a solvent residual rate (unit;%) is a dry-value value, specifically, when making x the mass of a solvent and y the mass of the casting film 32, it is {x / (yx)} x100 This value is obtained by.

The cooling process is performed by the 1st roller 27 in this embodiment. Therefore, as shown in FIG. 3, the flexible film 32 starts to fall after passing through 4th position P4. This temperature is referred to as second temperature below. In addition to the first roller 27, the cooling of the flexible film 32 may be accelerated by the gas cooled from the duct using a duct (not shown) through which a gas having a predetermined temperature flows out.

It is preferable to perform the cooling temperature maintenance process which maintains the temperature of the flexible film 32 in the temperature range in which crystallization of a polymer does not advance with respect to the flexible film 32 which started 2nd temperature drop. As a result, workability and reworkability are more surely improved.

When performing a cooling temperature maintenance process, it is more preferable to make time (t3) from the start of a cooling process until completion | finish of a cooling temperature maintenance process into the range of 1 second or more and 30 second or less. By setting t3 to 1 second or more, the flexible film 32 is more easily peeled from the band 29 than in the case of less than 1 second, and thus the manufacturing efficiency is further improved. Further, by setting t3 to 30 seconds or less, it is possible to prevent the progress of crystallization of the polymer 11, which deteriorates workability and reworkability as compared with the case longer than 30 seconds. In addition, when performing a cooling temperature maintenance process, it coincides at the time of peeling at the end of a cooling temperature maintenance process. When the cooling temperature holding step is not performed, the end of the cooling step coincides with the peeling.

At the time of peeling which peels the casting film 32 from the band 29, it peels, maintaining the temperature reached by the cooling process. Therefore, in FIG. 3, the temperature in the peeling position PP becomes the same as the temperature in a cooling temperature maintenance process.

The timing of peeling is preferable when the solvent residual ratio of the flexible film 32 is 20 mass% or more and 200 mass% or less, More preferably, it is the range of 30 mass% or more and 150 mass% or less, 40 mass% or more and 100 mass% It is more preferable when it is the range of% or less. When the solvent residual rate at the time of peeling is 20 mass% or more, the force required for peeling can be suppressed compared with the case where it is less than 20 mass%, and the shape deterioration of the film surface of the wet film 16 which arises at the time of peeling is prevented. can do. Moreover, when the solvent residual ratio at the time of peeling is 200 mass% or less, the thickness variation and optical variation of the film 23 can be suppressed to a fixed level or less compared with the case where it is larger than 200 mass%.

As mentioned above, in this invention, the surface orientation of the polymer in the wet film 16 at the time of peeling and after peeling is suppressed by performing each process of predetermined | prescribed casting film drying, heating temperature maintenance, cooling, and peeling. Thereby, while expressing sufficient workability and rework property to the film 23, the film 23 can be manufactured at the manufacturing speed equivalent to or more than the conventional cooling gelation casting method. Moreover, the film manufactured by the conventional method was one of the causes which generate | occur | produces the image deviation of a liquid crystal display, when it is attached to display apparatuses, such as a liquid crystal display, and is placed in severe use environment. However, the film 23 produced by the present invention also has the effect of reducing the occurrence of such image deviation.

In the present invention, since the constant temperature and the low temperature of the flexible film 32 are repeated, it is preferable to select a material having low temperature brittleness resistance as the band 29. Low temperature brittleness is a phenomenon which weakens rapidly at low temperature as it is well known. Low temperature brittleness resistance is a property that brittleness is not destroyed even at low temperatures. Low temperature here is the temperature reached by a 1st temperature fall and a 2nd temperature fall.

The suppression of the above-mentioned surface orientation improves further by applying the following method to a peeling process.

The process of peeling the flexible film 32 from the band 29 is demonstrated concretely, referring FIG. 4 and FIG. In FIG. 4, FIG. 5, the arrow Z1 shows the conveyance direction of the wet film 16, and the arrow Z2 shows the width direction of the wet film 16. In FIG. The width direction of the band 29 corresponds to the width direction Z1 of the wet film 16. 4 and 5 are schematic views, and the peeling roller 33 is drawn small for each thickness of the band 29 and the wet film 16.

In the following description, the space on one film surface side separated from the band 29 of the wet film 16 is referred to as the first space, and the space on the other film surface side is called the second space. The peeling roller 33 is arrange | positioned so that the longitudinal direction may correspond with the width direction of the exposed surface 29a which is the dope casting surface of the band 29. As shown in FIG. The release roller 33 is provided on the opposite side to the band 29 with respect to the conveyance path of the wet film 16. That is, since the band 29 is provided in the 1st space, the peeling roller 33 is provided in the 2nd space.

The peeling roller 33 is provided with the drive means 70 and the controller 71 which controls this drive means 70. By this drive means 70, the peeling roller 33 rotates to a circumferential direction at a predetermined rotational speed. The controller 71 controls the drive means 70 so that the peeling roller 33 may rotate at the set speed, when the signal of the rotation speed of the set peeling roller 33 is input.

The peeling roller 33 supports the wet film 16 which was guided by the circumferential surface, and conveys the wet film 16 by rotating. The band 29 and the peeling roller 33 are arrange | positioned so that the wet film 16 may be wound up by the peeling roller 33, and the conveyance path downstream of the peeling roller 33 is defined. Thus, the casting film 32 is peeled from the band 29 by winding up the wet film 16 on the peeling roller 33 and conveying the wet film 16 to the peeling roller 33.

Moreover, the peeling roller 33 may not necessarily be a drive roller, and what is called driven roller which follows by the circumferential surface contact | connects the wet film 16 conveyed may be sufficient. In this case, another conveying means is provided downstream of the peeling roller 33. The flexible film 32 is peeled from the band 29 by supporting the wet film 16 with the peeling roller 33 and conveying the wet film 16 by a conveying means provided downstream of the peeling roller 33. do.

The path control part 46 is provided in the 2nd space between the band 29 and the peeling roller 33, and controls so that the wet film 16 may be conveyed in the desired path | route. The path controller 46 includes a chamber 55, a pump 56, and a controller 57. The chamber 55 partitions the space to be depressurized from the external space. The pump 56 sucks in the atmosphere inside the chamber 55. The controller 57 controls the suction force of the pump 56. The controller 57 adjusts the suction force of the pump 56 so that when the signal of the set pressure in the inside of the chamber 55 is input, it will become that set pressure.

The chamber 55 includes a first member 61, a second member 62, a third member 63, a fourth member 64, and a fifth member 65. The 1st member 61 partitions the 2nd space which should be pressure-reduced with the outer space of the upstream in the conveyance direction Z1 of the wet film 16. As shown in FIG. The second member 62 partitions the second space to be decompressed from the outer space on the downstream side. The third member 63 and the fourth member 64 are partitioned from the outer space on each side in the width direction Z2. The fifth member 65 is partitioned from the outer space below. In addition, the first opening 68 is formed in the chamber 55 so as to be surrounded by the first to fourth members 61 to 64 to face the wet film 16. Aspirated from the first opening 68. The 1st-4th members 61-64 are arrange | positioned in the standing posture among the plate-shaped 1st-5th members 61-65.

The first member 61 is disposed to face the band 29 on the first roller 27 and has a curved surface along the band 29 on the first roller 27. In consideration of the thickness of the flexible film 32, the first member 61 is disposed so that the distance from the band 29 is in a range of 100 μm or more and 2500 μm or less. 61U of upstream ends of the 1st member 61 in the conveyance direction Z1 are located upstream rather than the downstream end 29D of the band 29. As shown in FIG.

The second member 62 is disposed to face the peeling roller 33 and has a curved surface along the circumferential surface of the peeling roller 33. In consideration of the thickness of the wet film 16, the second member 62 is disposed so that the distance from the peeling roller 33 is in a range of 100 μm or more and 2500 μm or less. The downstream end 62D of the second member 62 in the conveyance direction Z1 is located downstream from the upstream end 33U of the peeling roller 33. The second opening 69 is formed in the second member 62. The second opening 69 is connected to the pump 56, and gas inside the chamber 55 flows out.

The third member 63 and the fourth member 64 are disposed such that each inner surface thereof is outside the side edge 16e of the wet film 16. This prevents the wet film 16 from hitting the third member 63 and the fourth member 64 until the path is stabilized. The opposite surface facing the wet film 16 is curved in this embodiment so as not to overlap with the desired path of the wet film 16 in this embodiment when viewed from the side, but may not necessarily be curved. .

The interior of the chamber 55 is depressurized by the gas being sucked by the pump 56. When the inside of the chamber 55 is depressurized, the second space between the band 29 and the peeling roller 33 is also depressurized, resulting in a pressure lower than the first space. Thereby, the wet film 16 toward the peeling roller 33 changes a path from a straight path (symbol A shown by the broken line in FIG. 4) to a curved path so as to be pulled toward the chamber 55 side, and is laterally as shown in FIG. When viewed from the side, the conveying path is convex toward the second space side. Thus, the path control part 46 is a suction part which sucks the gas of the 2nd space between the band 29 and the peeling roller 33. As shown in FIG. By this suction, the second space between the band 29 and the peeling roller 33 is depressurized and the conveyance path of the wet film 16 is convex toward the second space side.

By making the conveyance path of the wet film 16 into convex shape to the 2nd space side, the force applied to the longitudinal direction of the wet film 16 of the force applied to the wet film 16 for peeling to a width larger than before. By making it small, more of the force provided can be used for peeling. For this reason, the surface orientation of the polymer of the wet film 16 can be suppressed, and as a result, workability and rework property are further improved.

Conventionally, when the peeling force is excessively large, the wet film 16 may be cut | disconnected at the time of peeling. The higher the manufacturing speed, the higher the solvent residual ratio at the time of peeling, so that the adhesion between the cast film 32 and the band 29 is greater. Therefore, the faster the manufacturing speed, the greater the peeling force, so the cutting becomes easier. In contrast, according to this embodiment, the force applied for peeling under a constant manufacturing speed can be further reduced. As a result, manufacturing speed can be made larger and manufacturing efficiency can be improved more. Moreover, according to the said method, gas is not sprayed on the wet film 16 with a very high solvent residual ratio immediately after peeling. For this reason, while the smoothness of the film surface of the wet film 16 is maintained, there also exists an advantage that the contamination by a foreign material can be avoided.

As described above, the exposed surface 29a of the band 29 at the peeling position PP and the wet film 16 are formed by controlling the path of the conveyance of the wet film 16 toward the release roller 33. Angle (theta) 1 can be enlarged and it becomes easy to suppress the force required for peeling low.

As for angle (theta) 1 which the band 29 and the wet film 16 in the peeling position PP make, it is more preferable to set it as the range of 30 degrees or more and 80 degrees or less.

When the angle θ1 between the band 29 and the wet film 16 at the peeling position PP is increased, the winding center angle θ2 with respect to the peeling roller 33 is the winding center angle in the case of the straight path A. Greater than When winding center angle (theta) 2 is large and easy to be maintained, the shape of the conveyance path between the band 29 and the peeling roller 33 will also become easier to hold | maintain as convex shape.

Moreover, the winding center angle (theta) 2 is the center angle in the linear form which consists of the winding area | region 72 in which the wet film 16 was wound by the peeling roller 33, and the cross section circular center of the peeling roller 33. As shown in FIG.

From the viewpoint of making the angle θ1 formed by the band 29 and the wet film 16 at the peeling position PP and the winding center angle θ2 larger, the peeling roller 33 is driven as in the present embodiment. It is more preferable to set it as a driving roller instead. What is necessary is just to reduce the rotational speed of a drive roller, when maintaining the shape of the conveyance path which convexed to the 2nd space side, or making it convex larger. Thus, the angle (theta) 1 and the winding center angle (theta) which the band 29 and the wet film 16 in the peeling position PP make the path | route of the conveyance of the wet film 16 toward the peeling roller 33 In addition to the method of making it larger by suction by the chamber 55, it can also be made larger by using the peeling roller 33 as a drive roller.

Although the 2nd space was depressurized in this embodiment so that a 2nd space may become a pressure lower than a 1st space, this invention is not limited to this. For example, you may pressurize a 1st space instead of or in addition to decompression of a 2nd space. However, this pressurization is pressurization at the static pressure, not pressurization at the dynamic pressure.

Pressurization as a positive pressure may be performed by the following method, for example. That is, the first space and the straight path A of the wet film 16 are surrounded by a chamber (not shown) to include a portion on the downstream side of the band 29 and a portion on the upstream side of the peeling roller 33. . The feeding operation which sends a gas into this chamber for a fixed time and the stop operation which stops a feeding operation for a fixed time are repeated. According to this pressurization method, generation | occurrence | production of the dynamic pressure called injection of gas can be suppressed largely, and pressure can be applied to the wet film 16 from the 1st space side. In addition, even when the gap between the band 29 and the peeling roller 33 is made into a very small gap of about several millimeters, this pressurization method can ensure a pressure difference between the first space and the second space. Moreover, even if it sucks gas from the slit-shaped opening extended in the width direction Z2, smoothness of a film surface can be maintained more reliably.

There is another method as a method for forming a pressure difference in the first space and the second space up to the band 29 and the release roller 33. For example, the internal space within the chamber 17 (see FIG. 1) without using the chamber 55 or the chamber (not shown) surrounding the straight path A of the first space and the wet film 16. There is a method of providing a partition member for partitioning the pressure difference therebetween. By controlling the pressure of each space formed by the partition member, the pressure difference can be formed in the 1st space above and the 2nd space below than the conveyance path of the wet film 16, respectively. When the distance between the band 29 and the peeling roller 33 is 5000 micrometers or more, it is more preferable to form the pressure difference using the chamber 55. FIG. When the distance between the band 29 and the peeling roller 33 is less than 5000 μm, the chamber 55 or the chamber (not shown) surrounding the straight path A of the first space and the wet film 16 is not used. Instead, the chamber 17 may be partitioned into partition members to form a pressure difference.

It is preferable to determine the difference of the pressure between a 1st space and a 2nd space based on the solvent residual ratio of the wet film 16 until it passes through the winding area | region in the peeling roller 33 from the peeling position PP. Do. It is preferable that the larger the solvent residual ratio is, the larger the pressure difference is, and the larger the convex path is. This is because the greater the solvent residual ratio, the stronger the adhesion between the band 29 and the flexible film 32, and the wet film 16 is more likely to break.

The peeling position PP is formed in the downstream side in the rotation direction of the band 29 so that it may go toward the center in the width direction Z2. For this reason, the force applied to the longitudinal direction of the wet film 16 at the time of peeling becomes large toward the center in the width direction Z2, and surface orientation becomes large. Therefore, at the peeling position PP, it is more preferable to make the pressure of a 2nd space lower as it goes to the center in the width direction Z2. Thereby, the film 23 whose surface orientation is constant in the width direction Z2 can be manufactured. In order for the pressure of the second space to be lowered toward the center at the peeling position PP, for example, an independent chamber (not shown) is further provided inside the chamber 55. There is a method of independently controlling each internal pressure of 55.

The peeling method in the above peeling process is especially effective when the polymer 11 (refer FIG. 1) is cellulose acylate.

The tenter 18 (see Fig. 1) is preferably provided with a pin and a clip as support means for supporting each side end, and is preferably switched from the pin to the clip at a predetermined timing. Thereby, while extending | stretching the wet film 16 to a predetermined direction, without impairing the suppression effect of the surface orientation of the polymer in the wet film 16 guided from the wet film forming apparatus, manufacturing efficiency improves further.

Thus, as a tenter 18 provided with both the support means of a pin and a clip, there exists a lateral stretch apparatus of patent 4169183, for example. The tenter 18 may be replaced with a plurality of tenters including a first tenter serving as a support means and a second tenter disposed downstream of the first tenter and serving as a support means for the clip. The aspect which arrange | positions these several tenters in series, and the structure of each tenter are described in patent 4169183. When using the some tenter connected in series, you may use a method for description in the same publication which injects air from below and floats a wet film with respect to a wet film in the conveyance path between a tenter and a tenter. Moreover, you may use the method containing what is called a longitudinal stretch process extending | stretching to a conveyance direction.

This invention is especially effective when manufacturing the film 23 in the range of 20 micrometers or more and 80 micrometers or less in thickness, and the range whose width is 1000 mm or more and 2600 mm or less. In the present invention, the concentration of the solid content in the dope 13 is preferably in the range of 15% by mass to 35% by mass from the viewpoint of suppressing the surface orientation of the polymer and the production efficiency of the film 23. In addition, the effect on the workability and the reworkability of the present invention is particularly remarkable when the expansion ratio in the tenter 18 is in the range of 1.1 times to 1.5 times. In addition, said solid content concentration in dope 13 is a percentage calculated | required by {A1 / (A1 + B1)} x100, when making mass of solid content A1 and solvent mass B1. Moreover, said widening ratio is a ratio calculated | required by B2 / A2, when making the width | variety of the wet film 16 before widening into A2, and the width | variety of the wet film 16 after widening into B2.

Moreover, when manufacturing the film 23 whose width is 2000 mm or more, the band 29 exceeding 2000 mm is used. In this case, it is necessary to use the band 29 in which a plurality of band materials forming the band are joined to each other by welding. In such a case, it is preferable to use those in which the joined portion joined by welding extends in the longitudinal direction of the band 29. It is because the use of the band 29 in which the junction part extended in the width direction raises the possibility that the optical property different from the shape of a film surface and another area | region will periodically arise.

Below, the Example of this invention and the comparative example with respect to this invention are described. Details are described in Example 1, and only the conditions different from those in Examples are described in other Examples and Comparative Examples.

Example 1

The film 23 whose thickness is 40 micrometers was manufactured from the dope 13 of the following prescription using the solution film forming installation 10 shown in FIG.

<Prescription of dope 13>

Solid ingredients ... Mass ratio in dope 13 is 20 mass%

solvent… A mixture of dichloromethane and alcohol, dichloromethane: alcohol = 80: 20

In addition, said solid component is a cellulose triacetate, a plasticizer, a mat agent, and a UV absorber as a polymer (11).

The temperature of the dope 13 at the time of casting is 34 degreeC. In the wet film forming apparatus 17, the casting film drying process, the heating temperature maintenance process, the cooling process, and the peeling process were performed. The temperature of the flexible film 32 reached by the 1st temperature drop is 10 degreeC, the temperature reached by the 1st elevated temperature, and the temperature of the flexible film 32 in the heating temperature maintenance process is 16 degreeC or more and 23 degrees C or less, a cooling process The temperature of the flexible film 32 which reached | attained by the 2nd low temperature in the temperature, and the temperature of the flexible film 32 at the time of peeling process are 15 degreeC. Moreover, the gelation temperature (TG) of the casting film 32 at the start of a cooling process was 10 degreeC.

As the tenter 18, a pin and a clip were used as the supporting means, and a switch was made from the pin to the clip at a constant timing. The expansion factor is zero.

About the obtained film 23, workability and reworkability were evaluated by the following method.

[Processability]

The obtained film 23 was laminated | stacked and adhere | attached on both surfaces of a polarizing film through an adhesive agent, and the polarizing plate was produced. The polarizing plate was punched into a rectangle of 10 cm x 10 cm with a blade and used as a sample for evaluation. Based on the following criteria, process adequacy was evaluated based on the following criteria whether the crack generate | occur | produced from the edge of one side of this evaluation sample, ie, a cut surface, into the inside of the film 23, and the degree of the confirmed crack. The crack may be a crack inward from the cut surface of the film 23, and may be peeling between the polarizing film and the film 23. In the following reference | standards, A-C is a level with which processing aptitude passes, and D is a level with which processing aptitude fails.

A: No cracks are observed or cracks are occurring, but the range of cracks is less than 25% of the length of one side

B: The range where the crack occurs is in the range of 25% or more and less than 50% of the length of one side

C: The range where a crack occurs is in the range of 50% or more and less than 75% of the length of one side.

D: The range where a crack occurs is more than 75% of the length of one side

[Reworkability]

The obtained film 23 was laminated | stacked and adhere | attached on both surfaces of a polarizing film through an adhesive agent, and the polarizing plate was produced. After bonding a polarizing plate to a glass substrate, it peeled from the glass substrate. It confirmed visually about the grade of the peeling residue of the film 23 on a glass substrate, and evaluated the rework property based on the following criteria. In the following criteria, A to C are levels at which the reworkability is passed, and D is a level at which the reworkability is failed.

A: No peeling residue was observed

B: degree of slight peeling residue

C: degree of peeling residue, but practically no problem

D: Many peeling residues

Moreover, the upper limit of the manufacturing speed of the film 23 which passed both aptitude and reworkability was calculated | required.

As a result, the processability of the film 23 obtained by the present Example was B, and the rework property was B. FIG. Moreover, the upper limit of the manufacturing speed was 120 m / min.

[Example 2]

The tenter 18 of Example 1 was replaced with the support means being a clip. Other conditions are the same as in Example 1.

The workability of the film 23 obtained in the present example was A, and the reworkability was A. Moreover, the upper limit of the manufacturing speed was 80 m / min.

Example 3

The film 23 was manufactured instead of the dope 13 used in Example 1 by the dope 13 of another prescription. The dope 13 used in the present Example adds 2 mass% of retardation expression agent with respect to 20 mass% of solid content in the prescription of the dope 13 of Example 1. As shown in FIG. The retardation expression agent has a function of increasing the retardation of the film 23 by adding the cellulose acylate. In addition, the kind of retardation expression agent is not specifically limited in this invention.

As a tenter 18, the same thing as Example 1 was used, and the amplification factor was 1.3. Other conditions are the same as in Example 1.

The processability of the film 23 obtained in the present example was C, and the reworkability was C. Moreover, the upper limit of the manufacturing speed was 120 m / min.

Example 4

The film 23 was manufactured instead of the dope 13 used in Example 1 by the dope 13 of another prescription. The dope 13 used in the present Example is the same as the dope 13 used in Example 3. As shown in FIG.

As a tenter 18, the same thing as Example 2 was used, and the amplification factor was 1.3. Other conditions are the same as in Example 2.

The processability of the film 23 obtained in the present example was C, and the reworkability was C. Moreover, the upper limit of the manufacturing speed was 70 m / min.

Example 5

The film 23 was manufactured instead of the dope 13 used in Example 1 by the dope 13 of another prescription. In the dope 13 used in the present embodiment, an ultraviolet (UV) cured material is added to the prescription of the dope 13 of the first embodiment.

As tenter 18, the same thing as Example 2 was used, and the amplification factor was set to 0 (zero). Other conditions are the same as in Example 2.

Workability of the film 23 obtained by the present Example was B, and the rework property was B. FIG. Moreover, the upper limit of the manufacturing speed was 100 m / min.

Comparative Example 1

The support body was made into the drum (not shown) rotating in the circumferential direction instead of the band 29, and the circumferential surface temperature of the drum was -5 degreeC. That is, this comparative example is a conventional cooling gelation casting method. 34 degreeC dope was cast | flow_spreaded, the casting film was formed, and this casting film was made -5 degreeC by the drum. The gelation temperature (TG) of the casting film 32 at the start of a cooling process was -2 degreeC. As the tenter 18, the support means used was a pin. Other conditions are the same as in Example 1.

The processability of the film obtained by this comparative example was D, and the rework property was D, and all failed. Moreover, in this comparative example, the manufacturing speed which pass | occur | produces both workability and reworkability was not confirmed, and the upper limit of the manufacturing speed obtained as a film was calculated | required. The result was 120 m / min.

Comparative Example 2

As tenter 18, the same thing as the comparative example 1 was used, and the amplification factor was 1.3. Other conditions are the same as in Example 1.

In this comparative example, the film was broken by the tenter 18 and a film could not be obtained.

Claims (11)

(A) casting a dope in which a polymer is dissolved in a solvent on a support to form a cast film;
(B) heating the flexible membrane to advance drying;
(C) maintaining the flexible film in a constant temperature range after the temperature has been lowered once during the B step;
(D) cooling the flexible film so that the flexible film is hardened without crystallization of the polymer in the flexible film after the C step;
(E) peeling from said support body the said flexible film as the wet film of the state containing a solvent, maintaining the temperature reached by the said cooling;
(F) step of drying the wet film
Solution film forming method comprising a. The method of claim 1,
By adjusting the circumferential surface temperature, the temperature of the flexible film is controlled through the support, and the endless support in the form of a band in contact with the circumferential surface is conveyed by a pair of rollers rotating in the circumferential direction,
In said A step, the said dope is cast with respect to the 1st winding area | region wound by the said one roller of the said support body,
The step B starts with respect to the flexible film facing the other roller;
Said C step supports the temperature of the said flexible film | membrane with the said other roller through the 2nd winding area | region of the said support body wound by the said other roller,
The said D step cools the said flexible film | membrane by the said one roller,
The said E step is a solution film forming method which peels the said flexible film from the said 1st winding area | region. The method of claim 1,
A solution film forming method for cooling the flexible film to a temperature range of TG or more and TG + 20 ° C. in step D when the gelation point of the flexible film is TG. The method of claim 1,
The said C step is a solution film forming method which maintains the temperature of the said flexible film until the residual ratio of the said solvent in the said flexible film becomes 100 mass%. The method of claim 1,
The solution film-forming method which makes time from the start of temperature rise in the said B step to the end of the said C step into 10 second or more and 100 second or less. The method of claim 1,
(G) Step of holding the said flexible film which started to fall by cooling in the said D step in a fixed temperature range before the said E step.
And a time from the start of the temperature drop by the cooling to the end of the G step in a range of 1 second to 30 seconds. The method of claim 1,
The film-forming method of irradiating the said live wire to the said flexible film, including the live hardening material hardened | cured by the irradiation of live wire in the said dope previously. The method of claim 7, wherein
And the live line is irradiated to the flexible film after the C step is started. The method of claim 1,
In the A step, the dope is continuously flexible,
It arrange | positions so that the longitudinal direction may correspond to the width direction of the said support body flexible surface, and winds up the said wet film in the circumferential surface of the peeling roller provided in the opposite side to the said support about the conveyance path of the said wet film, and conveys the said wet film. By peeling the flexible film,
When the space on one film surface peeled from the said support body of the said wet film is made into a 1st space, and the space on the other film surface is made into a 2nd space, the conveyance path of the said wet film toward the said peeling roller becomes the said 1st space. 2 The solution film-forming method which makes the pressure of the said 2nd space upstream from the said peeling roller smaller than the pressure of the said 1st space so that it may become convex toward the space side. The method of claim 9,
The solution film-forming method which sucks the gas of the said 2nd space upstream than the said peeling roller by the suction apparatus which sucks gas, and decompresses the said 2nd space between the said peeling position from which the said flexible film peels from the said peeling roller and the said support body. . The method of claim 10,
The suction device has a chamber for partitioning the second space to be depressurized from an outer space, and a solution film forming method for controlling a conveyance path of the wet film toward the peeling roller by adjusting a pressure in the chamber.

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