JP2003053749A - Solution film forming method and polarizing sheet protecting film, optical functional film and polarizing sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solution film forming method by which a conveying/ drying process can be stably performed and a high-quality film can be rapidly manufactured, when a film released from a casting support is dried while it is conveyed by a tenter, and a high-quality film can be rapidly manufactured. SOLUTION: A dope is cast to the casting support from a casting die and the cast dope is dried to some degree to form the film. Next, the film is released from the casting support, then both ends of the film are carried by a pin tenter and the film is dried while it is conveyed. In this film forming method, when the post-drying thickness of both ends of the film carried by the pin tenter is given as X μm and the average thickness of the finished product part of the film after drying is given as T μm, the relationship between X and T satisfies formula (1), formula (2) or formula (3). When T<=60, 40<=X<=200...(1). When 60<T<=120, 40+(T-60)*0.2<=X<=300...(2). When 120<T, 52+(T-120)*0.2<=X<=400...(3).

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a solution film-forming method for producing a cellulose triacetate film and the like, and a polarizing plate protective film, an optically functional film and a polarizing plate produced by the solution film-forming method.

[0002]

2. Description of the Related Art Generally, some films of cellulose acetate, polycarbonate, cellophane, etc. are manufactured by a solution casting method. In this solution film-forming method, a dope, which is a polymer solution, is cast from a casting die onto a belt-type or drum-type casting support, dried on the casting support to some extent to solidify, and then peeled off. The peeled film was dried while being transported while supporting both ends by a tenter device (Japanese Patent Laid-Open No. 62-46625, Japanese Patent Laid-Open No. 62-46626, etc.).

[0003]

However, when the film is peeled from the casting support in a state where the volatile content of the film is high, in the clip type tenter device, a hole is formed in the portion where the clip is in contact during transportation. There was a phenomenon that the film could not be carried by the tenter device. In particular, such a phenomenon is likely to occur when tension is applied in the width direction or when the film is stretched in the width direction when conveyed by a tenter device. Therefore,
It was difficult to perform high-speed casting, and the film production rate could not be improved.

Since the film peeled off from the casting support contains a large amount of volatile components, it sometimes foams when a clip tenter heated to a high temperature by dry air is brought into direct contact with the film. The foaming generated at the end portions of these films may reach the product portion, which is a quality problem. Further, the film may be cut due to tearing of the foamed portion.

In the pin type tenter device, the pin is penetrated through both ends of the film. If the thickness of the penetrating part is thin, the film is torn from the tenter device due to the tension caused by drying shrinkage. There was a case where disconnection occurred when desorbing. Further, when the thickness of the film at the pin penetration portion is thicker than necessary, the dope of the undried portion inside the film adheres to the pin itself, so that the pin may be contaminated and may cause conveyance failure.

The present invention solves the above problems, and when the film peeled from the casting support is dried while being conveyed by a tenter device, it can be stably conveyed and dried, and is excellent in quality. It is an object to provide a solution casting method capable of producing a film at high speed.

[0007]

Means for Solving the Problems The inventors of the present invention have made extensive studies in order to achieve the above objects, and have found conditions under which stable transportation and drying are possible, and have completed the present invention.

That is, phenomena such as perforation, cutting, and foaming of the film are controlled by the thickness of the film, the amount of volatile components remaining in the film, the temperature of the tenter, the atmosphere, the drying conditions, and the like. As a result of clarification and as a result of intensive studies, it was discovered that these optimum conditions were found and stable transportation and drying were possible.

[0009] Specifically, when carrying with a tenter device,
In addition to finding the minimum thickness of the portion to be carried, and finding a good relationship between the thickness of the portion to be carried and the portion to be the product, tearing due to stress due to drying shrinkage or the like is prevented. Further, it was found that the residual volatile component of the portion supported by the tenter device is good when it is within a specific range, and the phenomenon such as foaming is prevented from occurring.

According to the first aspect of the invention, the dope is cast from a casting die onto a casting support, the cast dope is dried to some extent to form a film, and the film is peeled from the casting support. A method for producing a film by carrying out drying while carrying both ends of the film with a pin tenter after transporting the film, wherein the dry thickness of both ends of the film carried by the pin tenter is X μm, When the average thickness of the product portion after drying is T μm, the relationship between the X and T satisfies the relationship of Expression (1), Expression (2) or Expression (3). When T ≦ 60, 40 ≦ X ≦ 200 …………………………………… (1) When 60 <T ≦ 120, 40+ (T-60) * 0.2 ≦ X ≦ 300 …… (2) When 120 <T, 52+ (T−120) * 0.2 ≦ X ≦ 400 ……… (3)

According to the second aspect of the invention, the dope is cast from a casting die onto a casting support, the cast dope is dried to some extent to form a film, and the film is peeled from the casting support. A method of producing a film by drying while taking and carrying both ends of the film with a clip tenter after the film is taken, the thickness after drying of both ends of the film carried by the clip tenter is X μm, When the average thickness of the product part of the film after drying is Tμm, the X and T
Is characterized by satisfying the relationship of Expression (4), Expression (5) or Expression (6). When T ≦ 40, 5 ≦ X ≦ T + 50 (4) When 40 <T ≦ 120, 20 ≦ X ≦ T + 100 (5) When T> 120, 60 ≦ X ≦ T + 200 ……………… (6)

According to the third aspect of the present invention, the dope is cast from a casting die onto a casting support, the cast dope is dried to some extent to form a film, and the film is peeled from the casting support. A method of producing a film by drying while taking and carrying both ends of the film with a pin tenter after the film is taken, in which residual volatile components at both ends of the film carried by the pin tenter are carried by the pin tenter. In this case, the content is 30 to 320% by mass.

According to a fourth aspect of the present invention, the dope is cast from a casting die onto a casting support, the cast dope is dried to some extent to form a film, and the film is peeled from the casting support. A method for producing a film by drying while taking and carrying both ends of the film with a clip tenter after taking, wherein the residual volatile components at both ends of the film carried by the clip tenter are It is configured to be 1 to 200 mass% when carried.

[0014]

The invention according to claim 1 is such that the dry thickness of both end portions of the film carried by the pin tenter is X μm, and the average dry thickness of the product portion of the film is T μ.
When m, the relation between X and T satisfies the relation of formula (1), formula (2) or formula (3). When T ≦ 60, 40 ≦ X ≦ 200 …………………………………… (1) When 60 <T ≦ 120, 40+ (T-60) * 0.2 ≦ X ≦ 300 …… (2) When 120 <T, 52+ (T−120) * 0.2 ≦ X ≦ 400 ……… (3)

The inventors of the present invention have made earnest studies and found that the thickness of both end portions of the film carried by the pin tenter has an appropriate range of thickness depending on the thickness of the product portion.
That is, if the thickness is less than 40 μm, the supported portion may be torn by the tension generated by drying, and the entire film may be broken in some cases. On the other hand, if the thickness exceeds 400 μm, a lot of solvent remains inside the film to cause foaming, and in some cases, the dope adheres to the pins and solidifies to adhere to the film, resulting in foreign matter failure. For such a foreign matter failure, a contact type dust removing device such as a brush or a device for removing dust with a liquid or gas is required at the detaching portion from the pin tenter.

Further, when T ≦ 60, when X exceeds 200, a large amount of solvent remains in the film to cause foaming, or dope adheres at the detached portion of the pin tenter,
It is not preferable because it becomes difficult to detach the dope, and the dope attached to the pins adheres to the film to become foreign matter. 60 <T ≦
At 120, when X is less than 40+ (T-60) * 0.2, the film-carrying part is thin, and the contraction force caused by drying causes tension around the pin, which makes it particularly easy to tear at the time of detachment. Not preferable.

Further, when X exceeds 300, a large amount of solvent (although it is combined with 0016 ...) is present in the film, foaming occurs, and dope adheres at the desorption portion of the pin tenter, resulting in desorption. Is difficult to do, and the dope attached to the pins adheres to the film as foreign matter, which is not preferable. When 120 <T, X is {52+ (T-12
If it is less than 0) * 0.2}, the film carrying part is thin,
It is not preferable because the contraction force generated by the drying causes the tension generated around the pin to easily tear the pin, especially at the time of detachment.

According to a second aspect of the invention, the thickness of the film carried by the clip tenter after drying is X.
μm, and the average thickness of the product part of the film is Tμm,
It is necessary that the relationship between X and T satisfies the relationship of Expression (4), Expression (5) or Expression (6). When T ≦ 40, 5 ≦ X ≦ T + 50 (4) When 40 <T ≦ 120, 20 ≦ X ≦ T + 100 (5) When 120 <T, 60 ≦ X ≦ T + 200 ……………… (6)

The inventors of the present invention have made earnest studies and found that the thickness of both end portions of the film carried by the clip tenter has an appropriate thickness range depending on the thickness of the product portion. That is, if it is less than 5 μm, a hole is generated at the contact portion with the clip, and (T + 200)
If the thickness exceeds μm, a film having a large amount of residual solvent and low rigidity may be torn by a clip, and it may not be possible to carry it by the clip.

When T ≦ 40, X is (T + 50)
When it exceeds, the stress is concentrated on the thin portion of the thickness changing portion due to the difference in thickness between the clip-carrying portion and the product portion, resulting in a non-uniform stretching state, which is not preferable. 40 <T ≦
At 120, when X is less than 20, the film is slipped at the clip carrying portion and uniform tension cannot be maintained, resulting in uneven physical properties and thickness, which is not preferable.

Further, when X exceeds (T + 100), the stress is concentrated on the thin portion of the thickness varying portion due to the difference in thickness between the clip carrying portion and the product portion, which is not preferable because of non-uniform stretching. When 120 <T, X is 60
If the amount is less than the range, the film may slip at the clip-carrying part and uniform tension cannot be maintained, resulting in uneven physical properties and thickness, which is not preferable.

In the invention according to claim 3, the residual volatile components at both ends of the film carried by the pin tenter are required to be 30 to 320 mass% when carried by the pin tenter, preferably 60 to It is 280 mass%, more preferably 80 to 250 mass%.

When the volatile component is less than 30 mass, it is difficult for the pin of the pin tenter to penetrate the film, which is not preferable. If the volatile component exceeds 320% by mass, the dope adheres to the penetrating pin and scatters upon detachment, adhering to the film and causing foreign matter failure. In addition, a brush used for penetrating the pin or the like is not preferable because the film adheres to the brush when contacted.

In the invention according to claim 4, the residual volatile components at both ends of the film carried by the clip tenter are
When supported by a clip tenter, the content is required to be 1 to 200% by mass, preferably 2 to 150% by mass, and more preferably 5 to 100% by mass.

When the volatile component is less than 1% by mass, the rigidity of the film is high and the friction resistance of the surface is generally lowered, so that the holding force of the clip is lowered and slippage occurs to maintain uniform tension. It is not preferable because it cannot be performed. Further, if the volatile component exceeds 200% by mass, foaming occurs and the quality of the product part is impaired, and the film may be cut from the foamed part.

In the present invention, the temperature of the tenter at the time of carrying the film is preferably not higher than the boiling point of the residual solvent of the film to be carried, and when the temperature is not higher than the boiling point, the film is carried during transportation. It is possible to prevent quality problems due to foaming of the portion, and to prevent the film from being broken during transportation, so that the film can be stably transported. Specifically, it is preferably 2 to 50 ° C. lower than the boiling point of the residual solvent. If the temperature of the tenter is higher than the temperature lower than the boiling point of the residual solvent by 2 ° C, foaming of the solvent cannot be effectively prevented. If the temperature of the tenter is lower than the temperature lower than the boiling point of the residual solvent by 50 ° C, the surrounding solvent gas or Moisture is condensed in the tenter,
It is not preferable because it solidifies to impair the function of the tenter, or they scatter and adhere to the film, resulting in foreign matter failure.

As described in JP-A-62-046625 and JP-B-62-046626, the pin tenter is a film containing a large amount of solvent volatile components, which is dried while applying tension without directly contacting with a roller or the like. By doing so, a film having very good flatness can be obtained. As for the pin tenter, it is possible to use only one stage for drying or use multiple stages for drying. However, if the temperature of the pin tenter rises due to the drying air during drying, the film newly carried on the pin tenter will cause foaming, resulting in poor conveyance. Therefore, these problems can be solved by adjusting the temperature of the pin tenter within the above range.

From the boiling point of the residual solvent, the tenter is set to 2-5.
In order to maintain the temperature at 0 ° C. lower, it is preferable to forcibly cool with a cooling means. The cooling means is not particularly limited, but a method of blowing cooling gas to the tenter,
It is preferable to use at least one of a method of spraying a volatile liquid, a method of directly cooling with a cooling liquid, a method of using a Peltier element, and a method of using a piezo element. In particular, a cooling gas that has a simple structure and does not scatter liquid is used. The method is preferred.

For example, the cooling can be performed while the film is conveyed and dried in the drying zone by the tenter chain, or it can be cooled even after the film is separated from the tenter and before it is caught.

In the former case, as means for preventing the temperature of the tenter from rising due to drying, a drying air shielding means for separating temperature conditions is provided between the film-carrying portion of the tenter and the film portion to be dried. Is effective.

The cooling may be performed by locally cooling the supporting portion of the tenter during drying, or may be performed after the film is detached and before the film is newly supported. The efficiency of cooling during drying is reduced because of the influence of hot dry air. On the other hand, cooling is highly efficient because it is not directly affected by the drying air while the film is detached and a new film is carried.

In order to cool the film more efficiently, it is preferable to remove the film and set the length until the film is newly carried to 10% to 60% of the entire length of the tenter. It is more preferably 20 to 50%, and most preferably 30 to 50%. If it is less than 10%, the cooling is insufficient, and if it is 60% or more, the drying is insufficient.

When the film peeled from the support is carried by the pin tenter, it is necessary to penetrate the film to some extent with the pin. For this purpose, a method of blowing gas or a method of pressing with a roll or a brush having a rotating function is effective. Also at this time, it is preferable to set the temperature of the gas and the temperature of the contact film supporting portion such as the brush to be 2 to 50 ° C. lower than the boiling point of the residual solvent and 2 to 50 ° C. higher than the dew point of the gas in the atmosphere. . If the temperature is higher than the boiling point of the residual solvent by 2 ° C. or less, the foaming of the solvent cannot be effectively prevented, and the film may adhere to the brush to cause a conveyance failure. If the temperature is lower than the boiling point of the residual solvent by 50 ° C, the surrounding solvent gas and water will condense on the tenter, solidify and impair the function of the tenter, or they will scatter and adhere to the film, resulting in foreign matter failure. Not preferred because of Furthermore, it is 2 to 50 ° C higher than the gelation temperature of the film.
The lower the better. The same applies to the clip tenter.

Further, the temperature of both ends of the film carried by the tenter is 2 more than the boiling point of the residual solvent of the film.
-50 ° C lower than the saturation temperature of the atmosphere gas 2 ~
It is preferably 50 ° C. higher.

When drying while being conveyed by a tenter,
When a high level of flatness is required, it is preferable to dry while applying tension in the width direction. In addition, the glass transition point (hereinafter,
It is also effective to stretch at a temperature of "Tg" or more). In this way, it is also possible to suppress the occurrence of chilimen-like irregularities that occur mainly in the casting direction due to drying and shrinkage.

The stretching ratio is preferably 1 to 30%. The stretching speed is preferably 1% / min to 100% / min. After stretching, the holding time is preferably 1 to 180 seconds.

The tension in the width direction applied to the film by supporting the tenter is preferably 1960 N / m (200 kg / m) or less. Tension is 1960 N / m (20
If it exceeds 0 kg / m), the film may break or the film may fall out of the clip, which is not preferable. In addition, unevenness may occur in the stretching of the portion supported by the clip and the portion other than that, and unevenness may occur in the minute temperature distribution and thickness distribution, which is not preferable.

It is also effective to use a simultaneous biaxially stretched tenter in order to suppress the occurrence of similar unevenness occurring in the width direction. It is effective to stretch the film having almost no residual solvent in the width direction and the casting direction at Tg or Tg or more as described above in order to improve the flatness, and even if two or more tenter conveying devices are installed in the process. It is also possible to stretch the film once wound using a tenter in another step.

Further, a film having a large residual solvent content immediately after peeling from the casting support often has a non-uniform shrinkage behavior due to a large difference in solvent amount between the front and back surfaces. For this reason, it is particularly preferable that the support surface side is not contacted with a roll or the like immediately after stripping. Similarly, even on the anti-support surface, it is preferable not to contact the roll or the like immediately after peeling. In order to obtain good flatness and surface condition, it is preferable that the total contact time on the surface side of the support is within 5 seconds after peeling from the casting support and before contactless conveyance by a tenter. It is more preferably within 3 seconds, and most preferably supported on a tenter without contacting the surface of the support. Similarly, on the side opposite to the support surface, after peeling off from the casting support,
It is preferable that the total contact time on the surface side of the support is within 10 seconds before non-contact conveyance by a tenter. It is more preferably within 5 seconds, and most preferably within 2 seconds.

After being peeled off from the casting support, when it is conveyed without contacting the roll with the support surface side, it is conveyed by contacting only the non-support surface side with an arched roll. The wrap angle is preferably 0.5 degrees or more. In addition, it is preferable that each of the rolls that convey the film to these tenters is appropriately equipped with a mechanism capable of controlling the draw ratio. The draw ratio from the stripped portion to the tenter is preferably 0 to 30%,
It is more preferably 0 to 20%, most preferably 0 to 10%.

Further, it is preferable that the roll can be cooled or heated by passing water inside, or by spraying a gas or induction heating. In addition, it is also effective to have a function of forming a temperature distribution in the width direction of the roll against the adhesion of dirt to the roll.

The surface treatment of the roll conveyed to the tenter may be flat, matte or dimple, and the surface treatment of the portion carrying the ears and the central portion of the film may be changed in order to prevent the film from wrinkling. For example, it is also preferable that the supporting portion is a dimple finish having a flattening rate of 50% and the central portion is flat finish.

The time of drying by the tenter conveying device is not particularly limited, but it is preferably dried for 20 seconds or more, more preferably 1 minute or more, and most preferably 2 minutes or more.

The solvent that evaporates from the film while being carried by the tenter is preferably 50 to 99% of the solvent that evaporates between the peeling of the casting support and the winding after drying. When it is less than 50%, the drying becomes insufficient, and while being supported by a tenter to apply tension,
The effect of drying to improve the flatness is lowered, which is not preferable in terms of film quality. Further, if it exceeds 99%, the length of the tenter zone becomes extremely long, which is not preferable in terms of space and cost.

The amount of solvent that is dried while being conveyed by a tenter is not particularly limited, and includes cases where there is almost no reduction in solvent. When the film is dried while being conveyed by a pin tenter immediately after being peeled off from the casting support, the change amount of the residual solvent of the film in the tenter part is preferably 20 to 320 mass%, more preferably 60 to 280 mass%. , 100 to 260 mass% is the most preferable. Further, in the clip type tenter, the change amount of the residual solvent of the film in the tenter portion is preferably 5 to 200% by mass, more preferably 10 to 150% by mass, and 20 to 1% by mass.
20 mass% is the most preferable.

The film is heated by hot air, microwaves, and conduction heat transfer when being dried while being conveyed by a tenter.
The temperature change of the film due to heating from the time when the film is supported on the tenter to the time when the film is removed from the tenter is preferably 10 to 180 ° C, more preferably 20 to 150 ° C, and further preferably 30 to 1
30 is most preferred. When the solvent is hardly evaporated, the film may be heated to Tg or higher than Tg. However, when the solvent evaporation process is substantially included, the drying temperature is particularly in the region of Tg + 20 ° C. or lower of the apparent film. It is preferable to carry out heating at.

Whichever heat transfer method is used, it is preferable that the temperature distribution in the width direction of the product portion inside the both end portions carried by the tenter is 10 ° C. or less.
The temperature is more preferably not higher than 0 ° C, further preferably not higher than 3 ° C, most preferably not higher than 2 ° C. When the temperature distribution exceeds 10 ° C, it becomes difficult to obtain a uniform surface shape.

For this purpose, the film preferably has a distribution of the overall heat transfer coefficient to the film in the film width direction of 10% or less, preferably 5% or less, due to hot air, infrared rays, microwaves, conduction heat transfer and the like. It is more preferably 3% or less, still more preferably 2% or less. In order to achieve these, if it is dry wind,
For example, in order to equalize the blowing air velocity from the slit, a jetting air velocity equalizing means such as a two-dimensional nozzle can be used. Further, even when using an ordinary slit or a perforated plate, it is possible to make the temperature of a film having a temperature distribution uniform in the width direction by providing a mechanism capable of controlling a plurality of temperatures in the width direction. Is.

[0049] It is preferable that the overall heat transfer coefficient of the film by the drying air is ^{5~300kcal / m 2 · hr · ℃} , it is less than ^{5kcal / m 2 · hr · ℃} , efficient in a short time Can not be heated well. 300 kcal
/ M ² · hr · ° C., the film will foam,
In some cases, crystallization is not preferable in terms of film quality.

It is preferable that the overall heat transfer coefficient of the tenter cooling by the cooling air is 10 to 300 kcal / m ² · hr · ° C, and if it is less than 10 kcal / m ² · hr · ° C, it is efficient in a short time. Can not be cooled. Also, 300
When it exceeds kcal / m ² · hr · ° C, the physical properties of the film supported on the tenter are changed, and tearing and film scraps are generated when the film is detached from the tenter, which is not preferable.

In the case of using radiant heat, it is also possible to make the substantial temperature of the film having a temperature distribution uniform in the width direction by adjusting the output of the heater in the width direction. The widthwise temperature distribution uniformizing mechanism of these films is preferably feedback-controlled by means for detecting the temperature distribution in the widthwise direction of the film. As the temperature detecting means, it is preferable to use a non-contact infrared radiation thermometer as well as a contact thermometer.

The widthwise wind velocity distribution on the film surface of the product portion inside the both ends supported by the tenter is preferably 10% or less, more preferably 5% or less, and 3% or less. Most preferably. If the widthwise wind speed distribution exceeds 10%, it becomes difficult to form a uniform surface.

The oxygen concentration in the drying zone by the tenter is 1
It is 0% or less, and the solvent gas generated in the drying zone can be condensed and recovered to reduce the water content in the solvent to 2% or less and then reused as a part of the raw material again. Further, both ends of the film detached from the tenter which were carried by the tenter can be continuously cut, and the cut portion can be reused as a part of the raw material. In particular, both ends of the film detached from the tenter, which were supported by the tenter, are continuously cut within 3 minutes after the tenter is removed, and the residual solvent amount at the cut end is 60% by mass or less. Is preferred. If the amount of residual solvent at the time of cutting exceeds 60% by mass, the rigidity of the film decreases and the cutting position changes when cutting with a fixed blade, a rotary blade or a vibrating blade, or defective cutting occurs. Is not preferable. In addition, the ear portion cut off with the residual solvent amount exceeding 60% by weight is unfavorably adhered to the duct when it is conveyed by a blowing method or the like.

In the solution casting method according to the present invention, a single layer liquid may be cast on a smooth band or a drum as a casting support, or a plurality of dopes of two or more layers may be cast. Good. When casting a plurality of dopes, the dope may be cast from a plurality of casting holes provided at intervals in the traveling direction of the support to form a film while laminating the dopes. -158414, JP-A-1-
122224, JP-A No. 11-198285, and the like can be applied. In addition, from the two casting ports
It may be cast or cast into a film. For example, JP-B-60-27562 and JP-A-61-9.
4724, JP-A-61-942245, JP-A-61
It can be carried out by the method described in JP-A-104813, JP-A-61-158413 and JP-A-6-134933. Further, a method of casting a cellulose acylate film described in JP-A-56-162617, in which a high-viscosity dope flow is wrapped with a low-viscosity dope and the high- and low-viscosity dopes are simultaneously extruded may be used.

Alternatively, using two casting ports, the film formed on the support by the first casting port is peeled off,
A film may be produced by carrying out a second casting on the side in contact with the support surface.
4-20235.

The dope to be cast may be the same solution,
Different dopes may be used and are not particularly limited. In order to impart a function to the plurality of cellulose acylate layers, dopes corresponding to the function may be extruded from the respective casting ports.
Further, the dope of the present invention is used for other functional layers (eg, adhesive layer, dye layer, antistatic layer, antihalation layer, UV layer).
It is also possible to cast the absorbing layer, the polarizing layer, etc.) simultaneously.

In the monolayer solution, it is necessary to extrude a high-concentration and high-viscosity dope in order to obtain the required film thickness, in which case the stability of the dope is poor and solid matter is generated.
This often caused problems such as a defective spot or poor flatness. As a solution to this problem, by casting a plurality of dopes through a casting port, a high-viscosity solution can be simultaneously extruded onto a support, and flatness can be improved to produce an excellent planar film. However, by using a thick dope, the reduction of the drying load can be achieved and the film production speed can be increased.

As the dope, a solution of cellulose acylate, polycarbonate, aramid polymer, norbornene polymer or the like can be used. As the cellulose acylate, it is preferable to use a lower fatty acid ester of cellulose. The lower fatty acid means a fatty acid having 6 or less carbon atoms. 2 carbon atoms
It is preferably (cellulose acetate), 3 (cellulose propionate) or 4 (cellulose butyrate). Cellulose acetate is particularly preferred. Mixed fatty acid esters such as cellulose acetate propionate and cellulose acetate butyrate may also be used.

The average degree of acetylation (degree of acetylation) of cellulose acetate is preferably 55.0% or more and less than 62.5%. From the viewpoint of the physical properties of the film, the average degree of acetylation is more preferably 58.0% or more and less than 62.5%. However, the average degree of acetylation is 55.0% or more.
Less than 0% (preferably 57.0% or more and less than 58.0%)
By using the cellulose acetate which is, it is possible to produce a film having a high retardation in the thickness direction.

When a cellulose acylate solution is used as the dope, at least 10 parts of cellulose acylate are used.
% Or more, and the substitution ratio A of the 6-position acylate group and the substitution ratio B of the remaining acylate group are preferably cellulose acylates satisfying the relationships of the formulas (7) and (8). It is more preferable that A ≧ 0.8 and the expression (8) is satisfied. A ≧ 0.75 ……………… (7) 2.5 ≦ A + B ≦ 3.0 …… (8)

By using a dope composed of such a cellulose acylate solution, a film having excellent solubility in an organic solvent, excellent fluidity, few foreign matters, high transparency and an optically isotropic film can be obtained. .

The organic solvent used for the dope includes hydrocarbons (eg benzene, toluene, cyclopentane, cyclohexane, cycloheptane, cyclooctane), halogenated hydrocarbons (eg methylene chloride, chlorobenzene), alcohols (eg methanol). , Ethanol, diethylene glycol, n-propyl alcohol, isopropyl alcohol, n-butanol, propanol, iso-propanol, 1-butanol, t-butanol, 2
-Methyl-2-butanol, 2-methoxyethanol,
2-butoxyethanol), ketone (eg acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclohexanone, methylcyclohexanone), ester (eg methyl acetate, ethyl acetate, propyl acetate,
Ethyl formate, propyl formate, pentyl formate, butyl acetate, pentyl acetate and 2-ethoxy-ethyl acetate) and ethers (eg tetrahydrofuran, methyl cellosolve, diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-
Dioxolane, anisole, phenetole) and the like.

Halogenated hydrocarbons having 1 to 7 carbon atoms are preferably used, and methylene chloride is most preferably used. From the viewpoint of physical properties such as solubility of cellulose acylate, peelability from a support, mechanical strength of a film, and optical properties, one or more kinds of alcohol having 1 to 5 carbon atoms are mixed with methylene chloride. It is preferable. The alcohol content is 2 with respect to the total solvent.
-25 mass% is preferred, and 5-20 mass% is more preferred. Specific examples of the alcohol include methanol, ethanol, n-propanol, isopropanol, n-butanol, etc., but methanol, ethanol, n
-Butanol or a mixture thereof is preferably used.

The solvent of the dope is 50 to 50% methyl acetate.
90%, acetone 0-40%, alcohol 5-40
% Is preferable. By using such a solvent, dissolution is facilitated, fluidity during casting is high, and peeling from the casting support can be facilitated. In addition, it is possible to obtain an optically isotropic film with high transparency and less foreign matter.

The dope used in the solution film-forming method of the present invention contains various additives (eg, plasticizers, ultraviolet absorbers, deterioration inhibitors, fine particle powders, release agents, etc.) depending on the use in each preparation step. An optical property adjusting agent and a fluorochemical surfactant) can be added. Further, the addition may be performed at any time in the polymer solution preparation step, but may be carried out by adding a step of adding an additive to the final preparation step of the polymer solution preparation step.

As the plasticizer, phosphoric acid ester or carboxylic acid ester is used. Examples of the phosphoric acid ester include triphenyl phosphate (TPP) and tricresyl phosphate (TCP), cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate and the like. Can be given. Typical carboxylic acid esters are phthalic acid esters and citric acid esters. Examples of phthalates include dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DB
P), dioctyl phthalate (DOP), diphenyl phthalate (DPP) and diethylhexyl phthalate (DEHP). Examples of citrate esters include:
O-Acetyl triethyl citrate (OACTE) and O
-Acetyl tributyl citrate (OACTB), acetyl triethyl citrate, acetyl tributyl citrate.

Examples of the other carboxylic acid ester include trimellitic acid esters such as butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, and trimethyl trimellitate. Examples of glycolic acid esters include triacetin, tributyrin, butylphthalylbutyl glycolate, ethylphthalylethyl glycolate, methylphthalylethyl glycolate, butylphthalylbutyl glycolate, and the like.

Among the plasticizers exemplified above, triphenyl phosphate, biphenyl diphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, tributyl phosphate, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate, It is preferable to use diethylhexyl phthalate, triacetin, ethylphthalylethyl glycolate, trimethyl trimellitate and the like. Particularly preferred are triphenyl phosphate, biphenyl diphenyl phosphate, diethyl phthalate, ethylphthalyl ethyl glycolate, and trimethyl trimellitate.

The above plasticizers may be used alone or in combination of two or more. The addition amount of the plasticizer is preferably 0.1 to 20% by mass with respect to the cellulose acylate,
15 mass% is more preferable. If the added amount is less than 0.1% by mass, the effect of addition cannot be sufficiently exhibited, and if the added amount exceeds 20% by mass, bleeding out may occur on the film surface.

In addition, in the present invention, as a plasticizer for reducing the optical anisotropy, JP-A-11-12444 is used.
No. 5, (di) pentaerythritol esters, glycerol esters described in JP-A No. 11-246704, diglycerol esters described in JP-A No. 2000-63560, citric acid esters described in JP-A No. 11-92574, Substituted phenyl phosphates described in JP-A No. 11-90946 are preferably used.

As the ultraviolet absorber, any kind can be selected according to the purpose. For example, salicylate-based, benzophenone-based, benzotriazole-based, benzoate-based, cyanoacrylate-based, nickel complex salt-based absorbers and the like can be selected. Although it can be used, a benzophenone type, a benzotriazole type, and a salicylic acid ester type are preferable. Examples of benzophenone-based UV absorbers include 2,4
-Dihydroxybenzophenone, 2-hydroxy-4-
Acetoxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2'-di-hydroxy-4-methoxybenzophenone, 2,2'-di-hydroxy-4,
4'-methoxybenzophenone, 2-hydroxy-4-
n-octoxybenzophenone, 2-hydroxy-4-
Dodecyloxybenzophenone, 2-hydroxy-4-
Examples thereof include (2-hydroxy-3-methacryloxy) propoxybenzophenone. As the benzotriazole-based ultraviolet absorber, 2 (2'-hydroxy-
3'-tert-butyl-5'-methylphenyl) -5-
Chlorbenzotriazole, 2 (2'-hydroxy-5 '
-Tert-butylphenyl) benzotriazole, 2
(2'-hydroxy-3 ', 5'-di-tert-amylphenyl) benzotriazole, 2 (2'-hydroxy-
3 ', 5'-di-tert-butylphenyl) -5-chlorobenzotriazole, 2 (2'-hydroxy-5'-t
Examples include ert-octylphenyl) benzotriazole and the like. Examples of salicylic acid ester include phenyl salicylate, p-octylphenyl salicylate, p-tert-butylphenyl salicylate and the like. Among these exemplified ultraviolet absorbers, 2-hydroxy-4-methoxybenzophenone, 2,2′-di-hydroxy-4,4′-methoxybenzophenone, 2 (2′-hydroxy-3′-tert-butyl-) is particularly preferable. 5'-methylphenyl) -5-chlorobenzotriazole, 2 (2'-hydroxy-5'-tert-butylphenyl) benzotriazole, 2 (2'-hydroxy-3 ', 5'-di-tert-amylphenyl ) Benzotriazole, 2 (2'-hydroxy-3 ', 5'-di-te
Particularly preferred is rt-butylphenyl) -5-chlorobenzotriazole.

It is preferable to use a composite of a plurality of UV absorbers having different absorption wavelengths, since a high blocking effect can be obtained in a wide wavelength range. The ultraviolet absorber for liquid crystal has a wavelength of 370 nm from the viewpoint of preventing deterioration of the liquid crystal.
From the viewpoint of liquid crystal display property, the following ultraviolet ray absorbing ability is preferable, and less visible light having a wavelength of 400 nm or more is preferable. For example, an oxybenzophenone compound,
Examples thereof include benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex salt compounds and the like. Particularly preferred ultraviolet absorbers are benzotriazole compounds and benzophenone compounds. Among them, the benzotriazole-based compound is preferable because the unnecessary coloring of the cellulose ester is small.

Regarding the ultraviolet absorber, see Japanese Patent Laid-Open No.
0-235852, JP-A-3-199201, 5
No. 1907073, No. 5-194789, No. 5-2
No. 71471, No. 6-107854, No. 6-11882.
No. 33, No. 6-148430, No. 7-11056,
7-11055, 7-11056, 8-29
No. 619, No. 8-239509, JP 2000-20.
It is described in each publication of No. 4173.

The amount of the ultraviolet absorber added is preferably 0.001 to 5 mass% with respect to the cellulose acylate, and is 0.0
1 to 1 mass% is more preferable. If the addition amount is less than 0.001% by mass, the effect of addition cannot be sufficiently exhibited, and if the addition amount exceeds 5% by mass, the ultraviolet absorber may bleed out to the film surface.

The ultraviolet absorber may be added at the same time when the cellulose acylate is dissolved, or may be added to the polymer solution after dissolution. In particular, it is preferable to use a static mixer or the like and add the ultraviolet absorbent solution to the polymer solution immediately before casting, because the spectral absorption characteristics can be easily adjusted.

The deterioration preventing agent can prevent the cellulose triacetate and the like from being deteriorated and decomposed. As the deterioration preventing agent, butylamine, hindered amine compound (JP-A-8-325537), guanidine compound (JP-A-5-274711), benzotriazole-based UV absorber (JP-A-6-235819), benzophenone-based UV absorber (JP-A-6-118)
233).

Among these, examples of the hindered amine compound include t-butylamine, triphenylamine, tribenzylamine and the like. Further, examples of the guanidine derivative include compounds represented by the following formulas (1a) and (1b).

[0078]

[Chemical 1]

The amount of the deterioration inhibitor added is 0.001 to 5%.
Is preferable, and 0.01-1% is more preferable. If the addition amount is less than 0.001%, the effect of addition is small, and if the addition amount exceeds 5%, the raw material cost increases, which is disadvantageous.

As the fine particle powder, silica, kaolin, talc, diatomaceous earth, quartz, calcium carbonate, barium sulfate, titanium oxide, alumina or the like can be arbitrarily used according to the purpose. Before adding these fine particle powders to the polymer solution, it is preferable to disperse them in the binder solution by any means such as a high speed mixer, a ball mill, an attritor or an ultrasonic disperser. Cellulose acylate is preferable as the binder. It is also preferable to carry out dispersion with other additives such as an ultraviolet absorber. Although the dispersion solvent is optional, it is preferable that the composition is similar to that of the polymer solution solvent.

The number average particle diameter of the fine particle powder is 0.01 to 10
0 μm is preferable, and 0.1 to 10 μm is particularly preferable.
The above dispersion may be added to the cellulose acylate dissolution step at the same time, or may be added to the polymer solution in any step, but it is preferable to add it just before casting using a static mixer or the like like the ultraviolet absorber.

The content of the fine particle powder is preferably 0.001 to 5% by mass, more preferably 0.01 to 1% by mass based on the cellulose acylate. If the addition amount is less than 0.001% by mass, the effect of addition cannot be sufficiently exhibited, and if the addition amount exceeds 5% by mass, the appearance surface condition may be deteriorated.

As the release agent, a surfactant is effective, and is not particularly limited to phosphoric acid type, sulfonic acid type, carboxylic acid type, nonionic type, cationic type. They are,
For example, it is described in JP-A-61-243837. The amount of the release agent added is preferably 0.002 to 2% by mass, and 0.01 to 1% by mass based on the cellulose acylate.
Is more preferable. If the addition amount is less than 0.001% by mass, the effect of addition cannot be sufficiently exhibited, and the addition amount is 2
When it exceeds the mass%, precipitation or insoluble matter may occur.

The nonionic surfactant is a surfactant having polyoxyethylene, polyoxypropylene, polyoxybutylene, polyglycidyl or sorbitan as a nonionic hydrophilic group, and specifically, polyoxyethylene alkyl. Ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene-polyoxypropylene glycol, polyhydric alcohol fatty acid partial ester, polyoxyethylene polyhydric alcohol fatty acid partial ester, polyoxyethylene fatty acid ester, polyglycerin fatty acid ester, fatty acid diethanolamide, Mention may be made of triethanolamine fatty acid partial esters.

The anionic surfactants are carboxylates, sulfates, sulfonates and phosphates, and representative ones are fatty acid salts, alkylbenzene sulfonates, alkylnaphthalene sulfonates,
Alkyl sulfonate, α-olefin sulfonate, dialkyl sulfosuccinate, α-sulfonated fatty acid salt, N-methyl-N oleyl taurine, petroleum sulfonate, alkyl sulfate, sulfated oil, polyoxyethylene Alkyl ether sulfate, polyoxyethylene alkyl phenyl ether sulfate, polyoxyethylene styrenated phenyl ether sulfate, alkyl phosphate, polyoxyethylene alkyl ether phosphate,
Examples include naphthalene sulfonate salt formaldehyde condensate.

As the cationic surfactant, an amine salt,
Examples thereof include quaternary ammonium salts and pyridum salts. First to third fatty amine salts, quaternary ammonium salts (tetraalkylammonium salts, trialkylbenzylammonium salts, alkylpyridinium salts, alkylimidazolium salts, etc.) ) Can be mentioned. Examples of the amphoteric surfactant include carboxybetaine and sulfobetaine, such as N-trialkyl-N-carboxymethylammonium betaine and N-trialkyl-N-sulfoalkyleneammonium betaine.

By adding the above-mentioned fluorine-containing surfactant, an antistatic effect can be exhibited. The addition amount of the fluorine-based surfactant is preferably 0.001 to 2% by mass, more preferably 0.01 to 0.5% by mass, based on the cellulose acylate. If the amount added is less than 0.002% by mass, the effect of addition cannot be sufficiently exhibited, and if the amount added exceeds 2% by mass, precipitation or insoluble matter may occur.

In the present invention, a retardation increasing agent (optical property adjusting agent) can be added. Optical anisotropy can be controlled by adding a retardation increasing agent. As the retardation increasing agent, it is preferable to use an aromatic compound having at least two aromatic rings in order to adjust the retardation of the cellulose acylate film. The aromatic compound was added in an amount of 0.
It is used in the range of 01 to 20 parts by mass. The aromatic compound is
0.05 to 100 parts by mass of cellulose acetate
It is preferable to use it within the range of
More preferably, it is used in the range of 10 to 10 parts by mass.
You may use together two or more types of aromatic compounds. The aromatic ring of the aromatic compound includes an aromatic hetero ring in addition to the aromatic hydrocarbon ring.

The aromatic hydrocarbon ring is a 6-membered ring (that is,
A benzene ring) is particularly preferable. The aromatic heterocycle is generally an unsaturated heterocycle. The aromatic heterocycle is preferably a 5-membered ring, a 6-membered ring or a 7-membered ring, more preferably a 5-membered ring or a 6-membered ring.
The aromatic heterocycle generally has the largest number of double bonds.
As the hetero atom, a nitrogen atom, an oxygen atom and a sulfur atom are preferable, and a nitrogen atom is particularly preferable. Examples of aromatic heterocycles include furan ring, thiophene ring, pyrrole ring,
Oxazole ring, isoxazole ring, thiazole ring,
Isothiazole ring, imidazole ring, pyrazole ring, furazan ring, triazole ring, pyran ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring and 1,3,3
A 5-triazine ring is included.

The molecular weight of the retardation increasing agent is 30.
It is preferably 0 to 800. The boiling point of the retardation increasing agent is preferably 260 ° C. or higher.
The boiling point is measured by a commercially available measuring device (for example, TG / DTA10
0, Seiko Denshi Kogyo Co., Ltd. can be used for measurement.

In the present invention, a coloring agent can be added. By adding a colorant, light piping can be prevented when it is used for a photosensitive material support or the like. The amount of colorant added is preferably 10 to 1000 ppm in terms of mass ratio to cellulose acylate,
-500 ppm is more preferable.

Further, to the dope of the present invention, a heat stabilizer such as a salt of an alkaline earth metal such as lucium or magnesium, an antistatic agent, a flame retardant, a lubricant, an oil agent, etc. may be added as necessary. it can.

When the dope used in the present invention is prepared, the container may be filled with an inert gas such as nitrogen gas.
The viscosity of the cellulose triacetate solution immediately before film formation may be in the range that can be cast during film formation, and is usually 10 ps.
It is preferably adjusted to the range of s to 2000 ps · s, and particularly preferably 30 ps · s to 400 ps · s.

The dope used in the present invention is prepared by a cooling melting method or a high temperature melting method. The cooling dissolution method will be described below. First, the temperature around room temperature (-1
Cellulose acetate is gradually added to the organic solvent with stirring at 0 to 40 ° C. When using a plurality of solvents, the order of addition is not particularly limited. For example, after adding cellulose acetate to the main solvent, another solvent (such as a gelling solvent such as alcohol) may be added, or conversely, the main solvent after pre-moistening the gelling solvent to cellulose acetate may be added. A solvent may be added, which is effective in preventing uneven dissolution. The amount of cellulose acetate is preferably adjusted so as to be contained in this mixture in an amount of 10 to 40% by mass. The amount of cellulose acetate is more preferably 10 to 30% by mass. Furthermore, any additives described below may be added to the mixture.

Then, the mixture is -100 to -10 ° C (preferably -80 to -10 ° C, more preferably -50 to-° C).
20 ° C, most preferably -50 to -30 ° C). For cooling, for example, a dry ice / methanol bath (-
75 ° C) or cooled diethylene glycol solution (-30
~ -20 ° C). When cooled in this way,
The mixture of cellulose acetate and organic solvent solidifies.
The cooling rate is not particularly limited, but in the case of batch-type cooling, the viscosity of the cellulose acetate solution increases with cooling, and the cooling efficiency is poor, so it is possible to use an efficient melting pot to reach a predetermined cooling temperature. is necessary.

Further, after swelling the dope of the present invention,
This can be achieved by transferring the cooling device having a predetermined cooling temperature for a short time. The faster the cooling rate, the better, but 100
00 ° C./sec is the theoretical upper limit, 1000 ° C./sec is the technical upper limit, and 100 ° C./sec is the practical upper limit. The cooling rate is a value obtained by dividing the difference between the temperature at the start of cooling and the final cooling temperature by the time from the start of cooling until the final cooling temperature is reached. Furthermore, this is 0-200 degreeC (preferably 0-150 degreeC, more preferably 0-120 degreeC, most preferably 0-50 degreeC).
When heated to (° C.), it becomes a solution in which cellulose acetate flows in an organic solvent. The temperature may be raised by leaving it at room temperature or by heating it in a warm bath. At this time, the pressure may be 0.3 to 30 MPa, but there is no particular problem. In that case, it is preferable to carry out the treatment as quickly as possible, preferably within 0.5 to 60 minutes, and particularly preferably 0.5 to 2
Short heating for a few minutes is recommended.

If the dissolution is insufficient, the cooling and heating operations may be repeated. Whether or not the dissolution is sufficient can be judged only by visually observing the appearance of the solution. In the cooling dissolution method, it is desirable to use a closed container in order to avoid mixing of water due to dew condensation during cooling. Further, in the cooling and heating operation, if the pressure is applied during cooling and the pressure is reduced during heating, the dissolution time can be shortened. In order to carry out the pressurization and depressurization, it is desirable to use a pressure resistant container.

A method for preparing a cellulose acetate solution by the high temperature dissolution method will be described below. First, cellulose acetate is gradually added to an organic solvent with stirring at a temperature around room temperature (-10 to 40 ° C). When using a plurality of solvents, the order of addition is not particularly limited. For example, after adding cellulose acetate in the main solvent,
Other solvents (eg gelling solvents such as alcohol) may be added, or conversely the main solvent may be added after the gelling solvent has been pre-moistened with cellulose acetate to prevent uneven dissolution. It is valid. The cellulose acetate solution of the present invention is preferably swelled in advance by adding cellulose acetate to a mixed organic solvent containing various solvents. In that case, in any solvent at -10 ~ 40 ℃,
Cellulose acetate may be gradually added with stirring, or in some cases, it may be swelled in advance with a specific solvent and then mixed with other concomitant solvent to form a uniform swelling liquid, and further, two or more solvents. The remaining solvent may be added after swelling with.

In the present invention, methyl acetate and a carbon number of 4 to 1
The dissolution concentration of cellulose acetate by the dissolution method of the mixed solvent system of the ketone solvent of 2 at high pressure and high temperature is preferably 30% by mass or less, and it is preferable that the concentration is as high as possible from the viewpoint of drying efficiency during film formation. The amount of cellulose acetate is adjusted so that the final dope is contained in an amount of 10 to 30% by mass. In the organic solvent composition of the present invention, it is preferable to prepare a high-concentration cellulose triacetate solution, but within the range. It may be charged at any concentration. If the concentration is too high, the viscosity of the solution may be too high, and it may be difficult to form a film. Therefore, the preferable concentration of the cellulose acetate solution is in the range of 15% by mass to 30% by mass. Further, the range of 17% by mass to 25% by mass is preferable.

Next, the organic solvent mixture is 0.2 MPa to 3 MPa.
It is heated to 70 to 240 ° C. under a pressure of 0 MPa (preferably 80 to 220 ° C., more preferably 100 to 200).
C, most preferably 100-190C). The heating may be, for example, high pressure steam or an electric heat source. A pressure resistant container or pressure resistant line is required for high pressure, but any pressure resistant container or line made of iron or stainless steel or other metal may be used without any particular limitation. Next, since these heated solutions cannot be applied as they are, it is necessary to cool them below the lowest boiling point of the solvent used. In that case, -10
It is common to cool to 50 ° C. and return to normal pressure. For cooling, a high-pressure high-temperature container or line containing a cellulose acetate solution may be left alone at room temperature, and more preferably, the apparatus may be cooled using a coolant such as cooling water. The heating and cooling operations may be repeated to accelerate the dissolution. Whether the dissolution is sufficient can be judged only by visually observing the appearance of the solution. In the high pressure high temperature melting method, a closed container is used to avoid evaporation of the solvent. Also, in the swelling step, the dissolution time can be further shortened by applying pressure or reduced pressure. In order to carry out pressurization and depressurization, a pressure resistant container or line is essential.

The film produced by the solution casting method of the present invention comprises a polarizing plate protective film, an optically functional film (optical compensation sheet,
Antireflection film, brightness enhancement film, etc.) and the like. A polarizing plate protective film, an optically functional film and the like are used in a liquid crystal display device, and this liquid crystal display device comprises a liquid crystal cell, a polarizing plate and an optical compensation sheet (retardation plate). In a transmissive liquid crystal display device, two polarizing plates are attached to both sides of a liquid crystal cell, and one or two optical compensation sheets are arranged between the liquid crystal cell and the polarizing plate. In a reflective liquid crystal display device, a reflector, a liquid crystal cell, one optical compensation sheet, and one polarizing plate are arranged in this order.

The liquid crystal cell comprises rod-shaped liquid crystalline molecules, two substrates for enclosing the rod-shaped liquid crystalline molecules, and an electrode layer for applying a voltage to the rod-shaped liquid crystalline molecules. The liquid crystal cell is different in the alignment state of rod-shaped liquid crystalline molecules.
Wisted Nematic), IPS (In-Pl)
ane Switching, FLC (Ferroe)
electric liquid crystal), OC
B (Optically Compensation B
end), STN (Super Twisted Ne)
MAT), VA (Vertically Alig)
ed) and reflective type, HAN (Hybrid)
Various display modes such as Aligned Nematic) have been proposed.

The polarizing plate generally comprises a polarizing film and a transparent polarizing plate protective film. This polarizing film is generally prepared by impregnating polyvinyl alcohol with an aqueous solution of iodine or a dichroic dye, and further coating this film. Obtained by uniaxial stretching. It has a structure in which two transparent polarizing plate protective films are attached to both sides of this polarizing film. Optical compensatory sheets are used in various liquid crystal display devices in order to eliminate image coloring and expand the viewing angle. A stretched birefringent film has been conventionally used as an optical compensation sheet.

Instead of the optical compensatory sheet comprising a stretched birefringent film, an optical compensatory sheet having an optically anisotropic layer formed of liquid crystalline molecules (particularly discotic liquid crystalline molecules) on a transparent support is used. Is proposed.
The optically anisotropic layer is formed by aligning liquid crystal molecules and fixing the alignment state. In general, liquid crystal molecules having a polymerizable group are used to fix the alignment state by a polymerization reaction. Liquid crystal molecules have large birefringence. The liquid crystal molecules have various alignment forms. The use of liquid crystal molecules has made it possible to realize optical properties that cannot be obtained by conventional stretched birefringent films.

The optical properties of the optical compensation sheet are determined according to the optical properties of the liquid crystal cell, specifically, the above-mentioned difference in display mode. By using liquid crystal molecules, particularly discotic liquid crystal molecules, it is possible to produce an optical compensation sheet having various optical properties corresponding to various display modes of a liquid crystal cell.

Optical compensatory sheets using discotic liquid crystal molecules have already been proposed for various display modes. For example, optical compensation sheets for TN mode liquid crystal cells are described in JP-A-6-214116, US Pat. Nos. 5,583,679 and 5,646,703, and German Patent Publication 3911620A1.
An optical compensation sheet for IPS mode or FLC mode liquid crystal cells is described in JP-A-10-54982. Further, an optical compensation sheet for OCB mode or HAN mode liquid crystal cell is described in US Pat. No. 5,805,253 and International Patent Application WO96 / 37804. Furthermore, an optical compensation sheet for STN-mode liquid crystal cells is described in JP-A-9-26572. An optical compensation sheet for a VA mode liquid crystal cell is described in Japanese Patent No. 2866372.

By laminating an optical compensation sheet using liquid crystalline molecules and a polarizing plate to form an elliptical polarizing plate, the optical compensation sheet can function as one polarizing plate protective film of the polarizing element. Such an elliptically polarizing plate has a layer structure in the order of a transparent protective film, a polarizing film, a transparent support, and an optically anisotropic layer formed of liquid crystal molecules. The liquid crystal display device has a feature that it is thin and lightweight, and if one of the constituent elements is used in combination, the device can be made thinner and lighter. Moreover, if one component of the liquid crystal display device is reduced,
One additional component attachment step is also eliminated, reducing the chance of failure during device fabrication. Japanese Unexamined Patent Publication (Kokai) No. Hei 7 (1999) -19987 discloses an integral elliptical polarizing plate in which a transparent support of an optical compensation sheet using liquid crystalline molecules and one protective film of the polarizing plate are commonly used.
-191217, 8-21996 and 8-9.
It is described in each publication of No. 4838.

In the case of producing an optical compensation sheet in which an alignment film and an optically anisotropic layer in which the alignment of liquid crystal molecules is fixed are provided on a transparent support, a transparent support (usually a cellulose acetate film) and an alignment film are used. Adhesion with (usually polyvinyl alcohol) is required. Usually, there is a problem that the cellulose acetate film and polyvinyl alcohol have poor affinity and peeling or cracking occurs. A gelatin subbing layer is provided on the cellulose acetate film in order to obtain adhesion between them.

The thickness of the transparent support is 20 to 500 μm.
Is preferable, and more preferably 40 to 200 μm.

When the transparent support is preferably optically isotropic, a usual cellulose ester film can be used. When the transparent support is required to have optical anisotropy, it is preferable to use a cellulose ester film having a high retardation. The in-plane retardation (Re) of the cellulose ester film can be adjusted (high value) by stretching the cellulose ester film. The retardation (Rth) in the thickness direction of the cellulose ester film is determined by (1) using a retardation increasing agent, (2) adjusting the average acetylation degree (acetylation degree), or (3) producing a film by a cooling dissolution method. Can be adjusted (higher value). As a result, the cellulose ester film, which has been conventionally considered to be optically isotropic, can now be used as an optically anisotropic transparent support having an optical compensation function.

The retardation value (Rth) in the thickness direction of the optically anisotropic support is preferably 60 to 1000 nm. Also, the in-plane retardation value (R
e) is preferably −50 to 50 nm, and
More preferably, it is 20 to 20 nm.

The retardation value in the thickness direction is a value obtained by multiplying the birefringence index in the thickness direction by the film thickness. The in-plane retardation value is a value obtained by multiplying the in-plane birefringence index by the film thickness. The specific value is the measurement direction of the in-plane retardation with the slow axis as the reference and the incident direction with respect to the vertical direction with respect to the film film surface It is determined by packaging from the measurement results that are tilted. The measurement can be performed using an ellipsometer (for example, M-150: manufactured by JASCO Corporation). The measurement wavelength is 632.8 nm (He-N
e laser) is adopted.

Retardation value in the thickness direction (Rth)
The in-plane retardation value (Re) is calculated according to the following equations (1) and (2), respectively. Formula (1) Rth = {(nx + ny) / 2-nz} * d Formula (2) Re = (nx-ny) * d

Where nx is the refractive index in the x direction in the film plane, ny is the refractive index in the y direction in the film plane, nz is the refractive index in the direction perpendicular to the film plane, and d Is the thickness (nm) of the film.

An example of a solution casting apparatus capable of carrying out the solution casting method according to the present invention will be described with reference to the drawings.

FIG. 1 is a schematic view of a main part of the solution film forming apparatus. Reference numeral 10 is a casting die, 20 is a drum as a casting support on which the dope is cast from the casting die 10, and 30 is a casting support. It is a tenter drying section for drying the film peeled off from the casting support 20. A stripping roll 21 for stripping the film from the casting support 20 is provided near the casting support 20. Also, the tenter drying unit 30
Is provided with a conveyance roll 32 inside the drying housing 31, and the tenter device 3 is provided between the conveyance rolls 32.
3 is provided, and the stripping roll 3 is provided on the most downstream side of the drying.
4 are provided.

In order to produce a film with the above solution casting apparatus, first, the dope (cellulose acetate solution) prepared from the dissolver (pot) is once stored in the storage pot,
Defoam the bubbles contained in the dope and make the final preparation.
The dope is sent from the dope outlet to the casting die 10 through a pressurizing type constant quantity gear pump capable of, for example, accurately feeding the dope according to the number of rotations, and the dope is uniformly cast onto the drum 20 running endlessly. Then, at a peeling point when the drum 20 is about one week old, the dry roll 21 peels off the dry thirsty dope film (hereinafter, simply referred to as a film). Both ends of the stripped film 40 are fixed by the tenter device 33, dried while being transported between the transport rolls 21, and separated from the tenter device 33 by the stripping roll 34. The separated film 40 is further dried, if necessary, and then conveyed to a winding step and wound on a winding roll.

[0118]

【Example】 [Example 1] <Dope A>   Cellulose triacetate (pulp raw material) …………………… 16% by mass   (Acetification degree 60.9%, degree of polymerization 305, 6-position acetyl substituent ratio 0.75, average (Particle size 1.5 mm)   Cellulose triacetate (pulp raw material) ………………………… 2% by mass   (Acetification degree 61.2%, degree of polymerization 322, 6-position acetyl substituent ratio 0.72, average (Particle size 1.1 mm)   Cellulose triacetate (raw material for linter) …………………… 2% by mass   (Acetification degree 61.2%, degree of polymerization 362, 6-position acetyl substituent ratio 0.72, average (Particle size 1.3 mm)   Triphenyl phosphate ………………………………………… 2% by mass   Biphenyl diphenyl phosphate ……………………………… 1% by mass   Benzotriazole type UV absorber ……………………………… 0.2 mass%   Silicon oxide matting agent (primary particle system 20 nm) ……………… 0.1 mass%   Methylene chloride ………………………………………………………… 67 mass%   Methanol ……………………………………………………………… 9% by mass   n-Butanol ………………………………………………………… 1 mass%   Peeling accelerator ………………………………………………………… 0.1 mass%   (Compound described in Specific Example 6 of Japanese Patent Application No. 63-129747)

<Dope B> The composition is the same as that of the dope A, but the solid content is diluted to 18.5 mass%.

<Preparation of casting dope> The dope A and the dope B were dissolved and filtered by the high temperature dissolution method described in Japanese Unexamined Patent Publication No. 2001-1745.

<Production of Film> A coat hanger type die was used as the casting die, hard chrome plating was applied as the casting support, and mirror finishing was performed so that the central average roughness was 0.03 μm. Diameter 4000mm, width 3800
A rotating drum having a diameter of 10 mm was used and the surface of the drum was kept at -10 ° C.

Then, the casting dope was cast onto a rotary drum with a width of 1600 mm from a coat hanger type die so that the thickness of the product part after drying was 40 μm and the thickness of both ends supported by the pin tenter was 50 μm. , Volatiles 25
After peeling at 0% by mass, both ends of the film were supported on a pin tenter. At this time, the temperature of the pin tenter was 25 ° C., the temperature of the carried film was 5 ° C., and most of the residual solvent in the film was methylene chloride. Also,
The saturation temperature of the atmosphere gas at the portion where the film was started to be supported on the pin tenter was -20 ° C, and the oxygen concentration was 6%.

The film supported on the pin tenter was introduced into the drying zone and dried with hot air while being conveyed in the drying zone. The temperature of the dry air is 120 ° C., the temperature distribution in the width direction at this time is 5 ° C. or less, the average wind speed of the dry air is 5 m / s, and the average value of the heat transfer coefficient is 25 kcal /
m ² · hr · ° C, and the widthwise distributions were all within 5%.

Further, in the drying zone, both end portions carried by the pin tenter were prevented from being directly hit by the dry hot air by the air shield device. Further, the film being conveyed by the pin tenter was dried while maintaining the tension in the width direction at 98 N / m (10 kg / m) in order to maintain the flatness of the film. The pin tenter was cooled with a total heat transfer coefficient of 150 kcal / m ² · hr · ° C by a cooling air of -5 ° C until the film was newly supported after the film was detached. The length of the portion cooled by the cooling device was 50% of the whole.

The time for supporting and drying by the pin tenter is 10 minutes, and the amount of solvent evaporated during that time is 97% of the total amount of solvent evaporated between peeling and winding.
%Met. The evaporated solvent is condensed and recovered by a condenser, and the recovered solvent is dehydrated by distillation to obtain a water content of 0.4%.
After that, it was used again as a raw material for the melting step.

[Comparative Example 1] Casting and drying were carried out under the same conditions as in Example 1 except that the average thickness and the thickness of the pin tenter supporting portion were changed to 30 µm.

Example 2 A similar dope A ′ except that the matting agent was removed from the dope A of Example 1 and a dope B similar to Example 1 were prepared, and the dope A ′ was dried to a thickness of 70 μm.
As the core portion corresponding to m, the dope B was used as the outer layers on both sides thereof, and was simultaneously laminated and cast on the same casting support as in Example 1 by using a multi-manifold die so that the thickness after drying was 5 μm. Then, the film peeled from the casting support was carried by a pin tenter in a state where the residual solvent was 280 mass% and the temperature was -2 ° C. Others were cast and dried under the same conditions as in Example 1.

Comparative Example 2 Casting and drying were performed under the same conditions as in Example 2 except that the cooling air was stopped. At this time, the temperature at which the pin tenter starts supporting the film is 45 ° C.
Met.

Example 3 <Preparation of Dope C> Cellulose triacetate powder (average size 2 mm) was mixed in a stainless steel dissolution tank having a stirring blade with the following solvent mixed solution cooled to 15 ° C. while being well stirred. Was gradually added and charged. 30 after addition
Cellulose triacetate was swelled by leaving it at 3 ° C. for 3 hours. As the solvent, methyl acetate, acetone, methanol, and ethanol were used, all of which had a water content of 0.2 mass% or less. Cellulose triacetate …………………………………………………… 18 parts by mass (Substitution degree 2.83, 6-position acylation rate 0.88, viscosity average degree of polymerization 320, pulp raw material cotton: linter raw material Cotton = 3: 7 (mass), water content 0.4 mass%, viscosity of 6 mass% in methylene chloride solution 305 mPA · s) Methyl acetate ………………………………………………………… ………… 54.3 parts by mass Acetone ……………………………………………………………… 10 parts by mass Methanol …………………………………… …………………………………… 5 parts by mass ethanol ……………………………………………………………… 10 parts by mass Plasticizer A …… ……………………………………………………………… 2 parts by mass (dipentaerythritol hexaacetate) Plasticizer B …………………… ………………………………………… 1.7 parts by mass (triphenyl phosphate) Fine particles (silica (particle size 20 nm)) ……………………………… 0.1 Mass part UV agent A ………………………………………………………… 0.1 mass part (2,4-bis- (n-octylthio) -6- ( 4-Hydroxy-3,5-di-TerT-butylanilino) -1,3,5-triazine) UV agent B ……………………………………………………………… 0.1 parts by mass (2 (2′-hydroxy-3 ′, 5′-di-TerT-butylphenyl) -5-chlorobenzotriazole) UV agent C ………………………………………… ………………………… 0.1 parts by mass (2 (2′-hydroxy-3 ′, 5′-di-TerT-amylphenyl) -5-chlorobenzotriazole) C ₁₂ H ₂₅ OCH ₂ CH ₂ OP (= O)-(OK) ₂ ……………… 0.05 parts by mass Citric acid ester …………………………………………………… 0 0.02 parts by mass

<Cooling and Dissolution of Dope C (Cellulose Triacetate Solution)> The cellulose acetate solution having the above composition was fed by a screw extruder having a jacket through which a refrigerant was passed, and cooled at -80 ° C. for 10 minutes. Passed through. Cooling was performed using a -90 ° C refrigerant cooled in a refrigerator. Then, the solution obtained by cooling was transferred to a stainless steel container and stirred at 50 ° C. for 2 hours. Then, it was filtered with a filter paper (# 63, manufactured by Toyo Roshi Kaisha, Ltd.) having an absolute filtration accuracy of 0.01 mm.

<Production of Cellulose Acetate Film>
On the drum for driving the band, the cooled and melted dope C was applied to a stainless belt (thickness: 1.5 mm, center line average roughness: 0.02 μm) having a width of 1800 mm and a length of 56 m, which was mirror-finished. It was cast from the first casting port in 1 to a casting width of 1650 mm. The temperature of the belt in the first casting part was set to 25 ° C. Furthermore, multilayer casting was sequentially performed with a casting width of 1700 mm from a second casting port installed at a position 25 m away from the first casting port. The temperature of the belt in the second casting part was set to 27 ° C. The casting thickness of each is 40 μm after drying, and the total thickness is 8
It was set to 0 μm.

After the dope was dried on the belt to some extent and solidified, it was peeled off from the belt when the residual volatile content reached 120%. Then, both ends of the peeled film were supported by a pin tenter. The temperature of the pin tenter at this time is 35 ° C, and the temperature of the film to be carried is 10 ° C.
And the thickness was 100 μm. Most of the residual solvent in the film was methyl acetate. Further, the saturation temperature of the atmosphere gas at the portion where the film was started to be carried on the pin tenter was −20 ° C., and the oxygen concentration was 6%. After being carried, the film entered the drying zone and was dried with hot air while being conveyed by a pin tenter. The temperature of this dry air is 1
40 ° C., the temperature distribution in the width direction at this time is 8 ° C. or less, the average wind velocity of the dry air is 5 m / s, the average value of the heat transfer coefficient is 25 kcal / m ² · hr · ° C., and the width direction is All distributions were within 5%.

Further, the pin-tenter-carrying portion in the drying zone was prevented from being directly hit by the dry air by means of an air shield. The film being conveyed by the pin tenter was maintained at a tension of 5 kg / m in the width direction in order to maintain the flatness of the film.

Further, the pin tenter was cooled by a cooling air of 0 ° C. with a total heat transfer coefficient of 150 kcal / m ² · hr · ° C. until the film was newly supported after the film was detached. The length of the portion cooled by the cooling device was 50% of the whole.

The film was supported by a pin tenter and dried for 10 minutes, and the amount of the solvent evaporated during that time was 93% of the total amount of the solvent evaporated from the peeling to the winding. The solvent evaporated in this drying step was condensed and recovered by a condenser, and the recovered solvent was dehydrated by distillation to have a water content of 0.2%, and then used again as a raw material for the solvent used for dope.

Example 4 The average thickness is 135 μm, the residual solvent amount of the film when peeled from the belt is 150%,
The temperature of the film part carried on the pin tenter is 12 ° C,
The thickness is 200 μm and the residual solvent amount is 220%,
It was dried while being transported under the same conditions as in Example 3.

[Comparative Example 3] While being conveyed under the same conditions as in Example 3, except that the temperature of both ends of the film carried on the pin tenter was 10 ° C, the thickness was 450 µm, and the residual solvent amount was 250%. Dried.

Example 5 The width of the dope A was set to 1800.
mm stainless steel belt with mirror surface 56 mm long (thickness 1.5 mm, center line average roughness 0.02 μ
m), the casting was performed so that the casting width was 1650 mm from the first casting port on the drum for driving the band.
The temperature of the belt in the first casting part was set to 20 ° C. Furthermore, multilayer casting was sequentially performed with a casting width of 1700 mm from a second casting port installed at a position 25 m away from the first casting port. The temperature of the belt in the second casting part was set to 27 ° C.
The casting thickness of each was 40 μm in terms of dryness, and the total thickness was 80 μm.

After the dope A was dried on the belt to some extent and solidified, it was peeled off from the belt when the residual volatile content reached 100%. Then, both ends of the peeled film were supported by clip tenter. At this time, the temperature of the clip tenter was 25 ° C., the temperature of the carried film was 20 ° C., and the thickness was 120 μm. Most of the residual solvent in the film was methylene chloride. Further, the saturation temperature of the atmosphere gas at the portion where the film starts to be supported on the clip tenter is −10 ° C., and the oxygen concentration is 6
%Met. After being carried, the film entered the drying zone and was dried with hot air while being conveyed by a clip tenter. The temperature of this dry air is 120 ° C., the temperature distribution in the width direction at this time is 6 ° C. or less, the average speed of the dry air is 5 m / s, and the average value of the heat transfer coefficient is 25 kcal / m ² · h.
r · ° C., and the distribution in the width direction was within 5% in all cases.

The clip tenter-carrying portion in the drying zone was prevented from being directly hit by the dry air by means of an air shield. The film being conveyed by the clip tenter has a tension of 196 N in the width direction in order to maintain the flatness of the film.
/ M (20 kg / m).

Further, the clip tenter has a total heat transfer coefficient of 120 kcal / m ² · hr · by the cooling air of −5 ° C. until the film is newly supported after the film is detached.
Cooled at ° C. The length of the portion cooled by the cooling device was 50% of the whole.

The time for the film to be carried by the clip tenter and dried was 5 minutes, and the amount of solvent evaporated during that time was 93% of the total amount of solvent evaporated from peeling to winding. . The solvent evaporated in this drying step is condensed and recovered by a condenser, and the recovered solvent is dehydrated by distillation to a water content of 0.2%.
It was used as a raw material for the solvent used for doping again.

[Embodiment 6] A width of 1800
mm stainless steel belt with mirror surface 56 mm long (thickness 1.5 mm, center line average roughness 0.02 μ
m), the casting was performed so that the casting width was 1650 mm from the first casting port on the drum for driving the band.
The temperature of the belt in the first casting part was set to 25 ° C. Furthermore, multilayer casting was sequentially performed with a casting width of 1700 mm from a second casting port installed at a position 25 m away from the first casting port. The temperature of the belt in the second casting part was set to 27 ° C.
The casting thickness of each was 40 μm in terms of dryness, and the total thickness was 80 μm.

After the dope was dried on the belt to some extent and solidified, it was peeled from the belt when the residual volatile content reached 120%. Then, both ends of the peeled film were supported by clip tenter. At this time, the temperature of the clip tenter was 35 ° C., the temperature of the film to be carried was 20 ° C., and the thickness was 100 μm. Most of the residual solvent in the film was methyl acetate. The saturation temperature of the gas in the atmosphere at the portion where the film started to be supported on the clip tenter was -5 ° C, and the oxygen concentration was 6%. After being carried, the film entered the drying zone and was dried with hot air while being conveyed by a clip tenter. The temperature of the dry air is 140 ° C., the temperature distribution in the width direction at this time is 8 ° C. or less, the average air speed of the dry air is 5 m / s,
The average value of the heat transfer coefficient was 25 kcal / m ² · hr · ° C, and the distribution in the width direction was within 5% in all cases.

The clip tenter-carrying portion in the drying zone was prevented from being directly hit by the dry air by means of an air shield. The film being conveyed by the clip tenter has a tension of 20 kg in the width direction in order to maintain the flatness of the film.
/ M.

Further, the clip tenter has a general heat transfer coefficient of 150 kcal / m ² · hr · ° C by cooling air of 0 ° C until the film is newly supported after the film is detached.
Cooled in. The length of the portion cooled by the cooling device was 50% of the whole.

The film was supported by a clip tenter and dried for 5 minutes, and the amount of the solvent evaporated during that time was 93% of the total amount of the solvent evaporated from the peeling to the winding. . The solvent evaporated in this drying step is condensed and recovered by a condenser, and the recovered solvent is dehydrated by distillation to a water content of 0.2%.
It was used as a raw material for the solvent used for doping again.

[Comparative Example 4] The film was conveyed and dried under the same conditions as in Example 5 except that the tension for stretching with a clip tenter was set to 300 kg / m.

[Comparative Example 5] The clip tenter was dried while being transported under the same conditions as in Example 6 except that the cooling air was stopped. At this time, the temperature at which the clip carried the film was 60 ° C.

[Evaluation of Casting Stability] In Examples 1 to 4, the film in the portion supported by the pin tenter was foamed,
It can be dried stably without tearing from the pin hole,
A film having good flatness could be obtained.

In Comparative Example 1, since the portion of the film carried by the pin tenter was thin, the film could not withstand the shrinkage force due to drying, and the film was torn from the pin hole and cut. In Comparative Example 2, foaming occurred from the pin hole, and when the film was detached from the pin, the film was torn and cut. In Comparative Example 3, since the film carried by the pin was thick, when the pin was released, undried dope was attached to the pin, resulting in poor pin detachment and cutting.

In Examples 5 and 6, the film of the portion supported by the clip could be stably dried without foaming or tearing from the pin hole, and a film having good flatness was obtained.

In Comparative Example 4, the film was broken during the tenter stretching, and the film could not be conveyed. In Comparative Example 5, foaming occurred during conveyance by the tenter, and a part of the foaming reached the product part, which was a level unusable as a product.

[Polarizing Plate Manufacturing Method and Evaluation Method] Polarizing plate samples were formed in Examples 1 to 6 by a polyvinyl alcohol adhesive on both surfaces of a polarizing element in which polyvinyl alcohol was stretched to adsorb iodine. The produced cellulose triacetate film was laminated and produced. This polarizing plate sample was exposed for 500 hours in an atmosphere of 60 ° C. and 90% RH. The degree of polarization is 99.6% in any of the examples.
It was above, and sufficient durability was recognized.

As for the polarization degree, the parallel transmittance Yp and the orthogonal transmittance Yc in the visible region were obtained by a spectrophotometer, and the polarization degree P was determined based on the following equation. P = √ ((Yp-Yc) / (Yp + Yc))

Example 7 <Preparation of Optical Compensation Sheet> Triacetyl cellulose film prepared in Example 3 [thickness: 100 μm, {(nX +
ny) / 2-nz} × d = 70 nm)], and a gelatin layer (layer thickness: 0.1 μm) was coated on one side. Next, a long-chain alkyl-modified poval (MP
-203, manufactured by Kuraray Co., Ltd., and applied 110
After being dried for 30 seconds in warm air at 0 ° C., rubbing treatment was performed to form an alignment film. On this alignment film, a discotic liquid crystal (the above compound example: 20% by mass of compound TE-8 (m = 4) described in JP-A-8-43625), and a photopolymerization initiator (IRGACURE 907, Ciba Geigy (Japan) Co., Ltd. )) Is 0.1% by mass, the coating solution dissolved in methyl ethyl ketone is applied by a slide coater.
Coating was performed at a coating speed of 20 m / min and a coating amount of 12 cc / m ² to form a discotic liquid crystal layer having a layer thickness of 2.4 μm. The film on which the alignment film and the liquid crystal layer are formed is 1
After the discotic liquid crystal was aligned by immersing it in a constant temperature bath set at 50 ° C for 5 minutes, the discotic liquid crystal was continuously heated at 150 ° C.
Irradiate with a mercury lamp (400 watts) for 2 minutes at ℃
An optical compensation sheet was obtained by allowing to cool to room temperature.

When the optical compensation sheet thus obtained was mounted on a TN type liquid crystal cell as shown in FIG. 2, the effect of improving the viewing angle was obtained without lowering the contrast. In FIG. 2, TNC is a TN type liquid crystal cell,
RF1 and RF2 are optical compensation sheets, A and B are polarizing plates, PA and PB are polarization axes, L0 is natural light, L1 and L5 are linearly polarized light, and L3 and L4 are elliptically polarized light.

[Example 8] In Example 1, the film detached from the pin tenter was continuously cut off by a rotary cutter at 10 seconds after the film was detached from the pin tenter, and transferred to a crusher by a blower to prepare chips. . The amount of residual solvent in the supporting portion when the supporting portion was cut off was 5% by mass. The removal of the carrying part and the blowing were stable.

[Comparative Example 6] In Example 8, the film carrying part from which the pin tenter was detached was cut off and passed through a roller drying zone in which the drying temperature was set to 130 ° C, and after 4 minutes of transportation, Wrinkles occurred and transportation became impossible.

[Example 9] In Example 1, a nylon rotating brush was used which continuously presses the film against the pin in order to bite it into the pin tenter. This brush was cooled to 0 ° C. with cooling air before use. The gelling temperature of the film at this time was 10 ° C. The boiling point of the residual solvent was 40 ° C, and the gas saturation temperature of the atmosphere was -15 ° C. The film could be squeezed in stably, and stable transfer was possible without the film sticking to the brush.

[Comparative Example 7] In Example 9, the brush was used after being cooled to 10 ° C with cooling air. The gelling temperature of the film at this time was 10 ° C. The boiling point of the residual solvent was 40 ° C, and the gas saturation temperature of the atmosphere was 2 ° C. When the film detached from the brush, it adhered to the brush, and biting into the bottle became very unstable. Also,
The film adhered to the brush was scattered and adhered to the product part of the film.

[0162]

INDUSTRIAL APPLICABILITY According to the present invention, when a film peeled from a casting support is dried while being conveyed by a tenter device, the film can be stably and rapidly dried without cutting or foaming.

[Brief description of drawings]

FIG. 1 is a schematic view of a main part of a solution film-forming apparatus for carrying out a solution film-forming method according to the present invention.

FIG. 2 is an exploded perspective view of a liquid crystal display device using a film produced by a solution casting method according to the present invention.

[Explanation of symbols]

10 ... Casting die 20 ... Drum 21 ... Stripping roll 30 ... Tenter drying section 31 ... Housing 32 ... Conveying roll 33 ... Tenter device TNC ... TN type liquid crystal cell A, B ... Polarizing plate PA, PB ... Polarization axis L0 ... Natural light L1, L5 ... Linearly polarized light L3, L4 ... Elliptical polarized light LC ... Arrangement state of liquid crystal molecules when sufficient voltage is applied to the TN liquid crystal cell RF1, RF2 ... Optical compensation sheet BL ... Backlight

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2H049 BA02 BA06 BB03 BB13 BB22                       BB23 BB33 BC03 BC09                 4F205 AA01 AA12 AA28 AA30 AB07                       AB10 AB11 AB14 AC05 AG01                       AG03 AK01 AK12 AR06 AR12                       GA07 GB02 GB26 GC02 GE24                       GF02 GN21 GN29 GW16 GW21

Claims (32)

[Claims] 1. A dope is cast from a casting die onto a casting support, the cast dope is dried to some extent to form a film, and the film is peeled from the casting support, and then both ends of the film are peeled off. A method for producing a film by carrying out drying while carrying a part of the film with a pin tenter, wherein the thickness of both ends of the film carried by the pin tenter is X μm, and the product part of the film after drying is Average thickness is T
.mu.m, the relationship between X and T can be expressed by equations (1) and (2).
Alternatively, a solution film-forming method characterized by satisfying the relationship of formula (3). When T ≦ 60, 40 ≦ X ≦ 200 …………………………………… (1) When 60 <T ≦ 120, 40+ (T-60) * 0.2 ≦ X ≦ 300 …… (2) When 120 <T, 52+ (T−120) * 0.2 ≦ X ≦ 400 ……… (3) 2. A dope is cast from a casting die onto a casting support, the cast dope is dried to some extent to form a film, and the film is peeled from the casting support, and then both ends of the film are peeled off. A method for producing a film by carrying out drying while carrying the part by a clip tenter, wherein the thickness of both ends of the film carried by the clip tenter after drying is X μm, and the product part of the film is dried. Assuming that the average thickness afterwards is T μm, the relationship between the X and T can be expressed by equation (4),
A solution film-forming method characterized by satisfying the relationship of formula (5) or formula (6). When T ≦ 40, 5 ≦ X ≦ T + 50 (4) When 40 <T ≦ 120, 20 ≦ X ≦ T + 100 (5) When 120 <T, 60 ≦ X ≦ T + 200 ……………… (6) 3. A dope is cast from a casting die onto a casting support, the cast dope is dried to some extent to form a film, and the film is peeled from the casting support, and then both ends of the film are peeled off. A method of producing a film by drying while carrying and transporting a part with a pin tenter, wherein the residual volatile components at both ends of the film carried by the pin tenter are 30 to 320 mass when carried by the pin tenter. %
The solution casting method is characterized by: 4. A dope is cast from a casting die onto a casting support, the cast dope is dried to some extent to form a film, and the film is peeled from the casting support, and then both ends of the film are peeled off. A method for producing a film by carrying out drying while carrying a part with a clip tenter, and when residual volatile components at both ends of the film carried by the clip tenter are carried by the clip tenter 1 ~ 2
A solution film-forming method, wherein the content is 00% by mass. 5. A dope is cast from a casting die onto a casting support, the cast dope is dried to some extent to form a film, and the film is peeled from the casting support, and then both ends of the film are peeled off. A method for producing a film by carrying out drying while carrying a part with a tenter, wherein the temperature of the tenter when carrying the film is 2 to 50 ° C. higher than the boiling point of the residual solvent of the film to be carried. The solution casting method according to claim 1, 2, 3, or 4, which is low. 6. A dope is cast from a casting die onto a casting support, the cast dope is dried to some extent to form a film, and the film is peeled from the casting support, and then both ends of the film are peeled off. A method for producing a film by carrying out drying while carrying a part by a tenter and transporting it, wherein the tenter is forcibly cooled by a cooling means. The solution film forming method according to. 7. The solution manufacturing method according to claim 6, wherein the cooling means is at least one of a method of spraying a cooling gas on a tenter, a method of spraying a volatile liquid, and a method using a Peltier element. Membrane method. 8. A dope is cast from a casting die onto a casting support, the cast dope is dried to some extent to form a film, and the film is peeled from the casting support, and then both ends of the film are peeled off. A method for producing a film by carrying a part by a tenter and transporting the film while drying the film, wherein the temperature rise of the tenter is prevented by a drying air shielding means. The solution film forming method according to 5, 6, or 7. 9. A dope is cast from a casting die onto a casting support, the cast dope is dried to some extent to form a film, and the film is peeled from the casting support, and then both ends of the film are peeled off. A method of producing a film by carrying out drying while carrying a part with a tenter, wherein the temperature of both ends of the film carried by the tenter is 2 to 50 ° C. lower than the boiling point of the residual solvent of the film. And 2 to 50 [deg.] C. higher than the saturation temperature of the gas in the atmosphere, the solution casting method according to claim 1, 2, 3, 4, 5, 6, 7 or 8. 10. A casting die is cast with a dope on a casting support, the cast dope is dried to some extent to form a film, and the film is peeled off from the film casting support. A method for producing a film by drying while supporting a part with a tenter, wherein the temperature of a member contacting the film before the film is detached from the tenter is 2 to 50 ° C. lower than the boiling point of the residual solvent of the film. And 2 to 50 ° C. higher than the saturation temperature of the gas in the atmosphere and 2 to 50 ° C. lower than the gelation temperature of the film. 11. A dope is cast from a casting die onto a casting support, the cast dope is dried to some extent to form a film, and the film is peeled from the casting support, and then both ends of the film are peeled off. A method for producing a film by carrying out drying while carrying the part by a tenter, wherein the solvent that evaporates from the film while being carried by the tenter is after drying from the casting support stripping. The solvent film forming method according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, wherein the solvent is 50 to 99% of the solvent that evaporates before winding. 12. A dope is cast from a casting die onto a casting support, the cast dope is dried to some extent to form a film, and the film is peeled from the casting support, and then both ends of the film are peeled off. A method for producing a film by carrying out drying while carrying a part by a tenter, wherein the oxygen concentration in the drying zone by the tenter is 10% or less, and the solvent gas generated in the drying zone is condensed and recovered. The water content in the solvent is reduced to 2% or less and then reused as a part of the raw material again.
The solution film forming method according to 6, 7, 8, 9, 10 or 11. 13. A dope is cast from a casting die onto a casting support, the cast dope is dried to some extent to form a film, and the film is peeled from the casting support, and then both ends of the film are peeled off. A method for producing a film by supporting the part with a tenter and transporting the film while drying the film, wherein the tension in the width direction applied to the film by the tenter is 19
60 N / m (1960 N / m (200 kg / m)) or less, 1, 2, 3, 4, 5, 6, 7, 8, 9, 1.
The solution casting method according to 0, 11 or 12. 14. A dope is cast from a casting die onto a casting support, the cast dope is dried to some extent to form a film, and the film is peeled from the casting support, and then both ends of the film are peeled off. It is a method of manufacturing a film by supporting a part with a tenter and transporting and drying the film, and the temperature distribution in the width direction of the product part inside the both end parts supported by the tenter is 10 ° C. or less. Claims 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 1
The solution casting method according to 2 or 13. 15. A dope is cast on a casting support from a casting die, the cast dope is dried to some extent to form a film, and the film is peeled from the casting support, and then both ends of the film are peeled off. A method for producing a film by carrying out drying while carrying a part with a tenter, wherein the width direction wind velocity distribution on the film surface of the product part inside the both end parts carried by the tenter is 10% or less. Claims 1, 2, 3, 4, 5, 6, 7, 8,
The solution film-forming method as described in 9, 10, 11, 12, 13 or 14. 16. A dope is cast from a casting die onto a casting support, the cast dope is dried to some extent to form a film, and the film is peeled from the casting support, and then both ends of the film are peeled off. It is a method of manufacturing a film by carrying it while carrying it with a tenter and transporting it, and the overall heat transfer coefficient of the heat transfer of the film by the dry air is 5 to 300 kcal /
m ² · hr · ° C. 3.
3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 1
The solution film-forming method as described in 3, 14, or 15. 17. A dope is cast from a casting die onto a casting support, the cast dope is dried to some extent to form a film, and the film is peeled from the casting support, and then both ends of the film are peeled off. A method for producing a film by carrying while transporting a part with a tenter and transporting the film, wherein the overall heat transfer coefficient of the tenter cooling by the cooling means is 10 to 300 kcal.
/ M ² · hr · ° C, 7.
7. The solution film forming method according to 7, 8, 9, 10, 11, 12, 13, 14, 15 or 16. 18. A dope is cast from a casting die onto a casting support, the cast dope is dried to some extent to form a film, and the film is peeled from the casting support, and then both ends of the film are peeled off. A method for producing a film by drying while carrying the part by a tenter while transporting, the both ends of the film detached from the tenter which were carried by the tenter are continuously cut off, and the cut part is Reusing as a part of raw material, 1, 2, 3, 4, 5,
6, 7, 8, 9, 10, 11, 12, 13, 14, 1
The solution film-forming method according to 5, 16, or 17. 19. A dope is cast on a casting support from a casting die, the cast dope is dried to some extent to form a film, and the film is peeled off from the casting support.
A method for producing a film by drying while supporting both ends of a film with a tenter, wherein both ends supported by the tenter of the film detached from the tenter are continuously removed within 3 minutes after the tenter is detached. 19. The solution film-forming method according to claim 18, wherein the amount of residual solvent at the end part of the cutting process is 60 wt% or less. 20. The dope is a solution containing any one of cellulose acylate, polycarbonate, aramid polymer and norbornene polymer, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 1
The solution film-forming method according to 2, 13, 14, 15, 16, 17, 18 or 19. 21. The dope is a dope containing at least 10% of cellulose acylate, wherein the substitution ratio A of the 6-position acylate group and the substitution ratio B of the remaining acylate group are represented by the formula (7) and Claims 1, 2, 3, 4, 5, 6, 7, satisfying the relationship of Expression (8).
8, 9, 10, 11, 12, 13, 14, 15, 16,
The solution film-forming method as described in 17, 18, 19 or 20. A ≧ 0.75 ……………… (7) 2.5 ≦ A + B ≦ 3.0 …… (8) 22. The solvent of the dope is methyl acetate
0 to 90%, acetone 0 to 40%, alcohol 5 to
The solution film-forming method according to claim 21, wherein the method comprises 40%. 23. The dope contains at least one plasticizer in an amount of 0.1 to 20% by mass based on cellulose acylate.
23. The solution film-forming method according to claim 21, wherein the solution film-forming method comprises: 24. The dope contains 0.001 to at least one ultraviolet absorber with respect to cellulose acylate.
22, 2 characterized in that it contains 5% by mass.
The solution casting method according to 2 or 23. 25. The dope contains 0.001 to 5 of at least one kind of fine particle powder with respect to cellulose acylate.
21. The method according to claim 21, wherein the content is% by mass.
The solution film forming method according to 2, 23 or 24. 26. The dope contains 0.002 to 2 mass% of at least one mold release agent with respect to the cellulose acylate.
The solution casting method according to 3, 24 or 25. 27. The dope contains at least one fluorine-based surfactant in an amount of 0.00 to cellulose acylate.
The content is 01 to 2% by mass.
The solution film-forming method as described in 1, 22, 23, 24, 25, or 26. 28. When casting the dope from the casting die onto the casting support, two or more kinds of dopes are co-cast. , 7, 8,
9, 10, 11, 12, 13, 14, 15, 16, 1
7, 18, 19, 20, 21, 22, 23, 24, 2
The solution film-forming method as described in 5, 26 or 27. 29. When the dope is cast from the casting die onto the casting support, two or more kinds of dopes are sequentially cast in a multi-layer casting process. 5, 6,
7, 8, 9, 10, 11, 12, 13, 14, 15, 1
6, 17, 18, 19, 20, 21, 22, 23, 2
The solution film-forming method as described in 4, 25, 26, or 27. 30. Claims 1, 2, 3, 4, 5, 6, 7,
8, 9, 10, 11, 12, 13, 14, 15, 16,
17, 18, 19, 20, 21, 22, 23, 24, 2
A polarizing plate protective film produced by the solution film-forming method described in 5, 26, 27, 28 or 29. 31. Claims 1, 2, 3, 4, 5, 6, 7,
8, 9, 10, 11, 12, 13, 14, 15, 16,
17, 18, 19, 20, 21, 22, 23, 24, 2
An optical functional film produced by the solution film-forming method described in 5, 26, 27, 28, 29, or 30. 32. A polarizing plate comprising the polarizing plate protective film according to claim 30 and / or the optical functional film according to claim 31.