JP2002036263A - Method and apparatus for manufacturing film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film manufacturing technique capable of effectively suppressing a curl phenomenon generated in a film when the film with a thickness of 20-85 μm is manufactuered. SOLUTION: The film manufacturing technique includes a dope casting process for casting a dope, which is a raw material solution of the film, on a support 2 from a die 10, a peeling process for peeling the web W, which is formed on the support in a dope casting process, from the support, a drying process for drying the web W, which is peeled from the support in the peeling process, while feeding the same through a plurality of feed rolls 12 and a taking-up process for taking up the film F obtained by drying the web in the drying process. The drying time of the web, in such a state that the web is in contact with the support, is set to 0.3-20 min and the temperature of the air sprayed on the web being in contact with the support and the temperature of the contact surface of the support are set to 5-100 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film used for an optical film useful for various display devices such as a liquid crystal display device or an organic electroluminescence display, and more particularly to a protective film for a polarizing plate used for these display devices. And a production technique for a film useful for a retardation film.

[0002]

2. Description of the Related Art Liquid crystal display devices (hereinafter referred to as LCDs) have various excellent characteristics, and are currently used for display of word processors, personal computers, and various information communication devices. Widely used as a device.

[0003] The LCD basically has a structure in which polarizing plates are attached to both sides of a liquid crystal cell, and the polarizing plate functions to pass only light having a certain polarization plane. That is, LCD
In, the polarizing plate plays an important role of visualizing the change in the orientation of the liquid crystal due to the electric field. Therefore, the performance of the LCD greatly depends on the quality of the polarizing plate.

Here, the structure of the polarizing plate will be briefly described. The polarizing plate has a three-layer structure in which a polarizer is sandwiched between polarizing films on both sides thereof. As described above, the LCD is configured by laminating the thus obtained polarizing plate on a liquid crystal cell.

[0005] Among the above components, the polarizer is obtained by adsorbing iodine or the like on a polymer film and stretching the polymer film. Specifically, H containing a dichroic substance (iodine)
A solution called ink is wet-adsorbed on a polyvinyl alcohol film, and then the film is uniaxially stretched to orient the dichroic substance in one direction. On the other hand, a cellulose resin, particularly cellulose triacetate, is used as the polarizing plate protective film.

[0006] The polarizing plate protective film is manufactured using a band casting system. The structure of the band casting apparatus is already known, but generally speaking,
A casting die is provided immediately above the casting band, and a peeling roll, a drying unit, and a winding roll are sequentially provided after the casting band. The polarizing plate protective film,
First, after casting the dope from the casting die onto the casting band,
It is obtained by peeling the web from the casting band with a peeling roll and completely drying the web in a drying section. After this,
The obtained film is wound up by a winding roll.

Incidentally, the polarizing plate protective film currently used has a thickness of 85 μm or more. However, recently, a thin polarizing plate protective film having a thickness of less than 85 μm, particularly a thickness of 20 μm or more and less than 85 μm has been required.

However, in the conventional manufacturing technique, the thickness is 20 to
It is difficult to obtain a polarizing plate protective film of 85 μm and high quality. That is, the thickness is 20 to 85 in the prior art.
When a thin polarizing plate protective film having a thickness of μm is produced, the curl of the film becomes so large that it cannot be ignored. Needless to say, such a failure is a major cause of significantly lowering the quality of the polarizing plate protective film.

Therefore, an object of the present invention is to provide a film manufacturing technique capable of efficiently obtaining a high-quality film having a thickness of 20 to 85 μm. In particular, it is an object of the present invention to provide a film manufacturing technique capable of effectively suppressing a curl phenomenon in which a curl occurs in a film obtained when a film having a thickness of 20 to 85 μm is manufactured.

[0010]

An object of the present invention is to provide a method for producing a film having a thickness of 20 to 85 μm by using a solution casting method, wherein a raw material solution of the film is formed on a support. A dope casting step of casting a certain dope from a die, a peeling step of peeling the web formed on the support in the dope casting step from the support, and the support in the peeling step A drying step of drying the web separated from the web while being transported through a plurality of transport rolls, and a winding step of winding a film obtained by drying the web in the drying step. The drying time of the web in the state where the web is in contact with the support is set to 0.3 to 20 min, and the temperature of the gas blown to the web in the state in contact with the support and The temperature of the contact surfaces of the serial support, 5
The problem is solved by a film manufacturing method characterized in that the temperature is not lower than 100 ° C. and not higher than 100 ° C.

Another object of the present invention is to provide an apparatus for producing a film having a thickness of 20 to 85 μm using a solution casting method, wherein a dope as a raw material solution of the film is poured on a support. Dope casting means provided with a die for spreading, a web formed on the support by the dope casting means, peeling means for peeling from the support,
A drying unit configured to dry the web separated from the support by the separation unit while being transported through a plurality of transport rolls; and a winding unit configured to wind the film obtained by drying the web by the drying unit. Further comprising a first drying means for blowing a gas onto the web formed on the support by the dope casting means in a section from the dope casting means to the peeling means. A treatment unit, a second drying treatment unit that is located at a position facing the first drying treatment unit across the support, and heats the web via the support, and the first drying treatment. Section and a second pair of drying processing sections, and constitutes a drum pair that circulates and runs the support.
A third drying unit for heating the web via the support, a drum on one side which is a third drying unit, and a fourth drying unit which is provided subsequent to the third drying unit and blows a gas onto the web. A processing unit, a fifth drying unit which is located at a position facing the fourth drying unit with the support interposed therebetween, and heats the web via the support, and a fourth drying unit. Section and the fifth drying section,
A pair of drums for circulating the support, and a drum on the other side, which is a cooling processing unit for cooling the web via the support, is provided. The average drying temperature is equal to or higher than the average drying temperature of the fourth drying section, and / or the average heat transfer coefficient of the first drying section is the average heat transfer coefficient of the fourth drying section. The problem is solved by a film manufacturing apparatus characterized by being configured to have a coefficient or more.

[0012] In the film manufacturing apparatus of the present invention, the drying temperature of the first drying section decreases from the upstream side to the downstream side along the support running direction, and / or It is preferable that the heat transfer coefficient of the first drying section is configured to decrease from the upstream side to the downstream side along the support running direction.

[0013] In the above-mentioned film manufacturing apparatus, the drying temperature of the fourth drying section is decreased from the upstream side to the downstream side in the traveling direction of the support, and / or It is preferable that the heat transfer coefficient of the fourth drying section is configured to decrease from the upstream side to the downstream side along the support running direction.

On the contrary, an object of the present invention is to provide a method of manufacturing a film using the above-described film manufacturing apparatus, wherein the average drying temperature of the second drying section is equal to or higher than the average drying temperature of the third drying section. In addition, the invention is solved by a film manufacturing method, wherein the average drying temperature of the third drying section is equal to or higher than the average drying temperature of the fifth drying section.

Another object of the present invention is to provide a method of manufacturing a film using the above-described film manufacturing apparatus, wherein the average heat transfer coefficient of the second drying section is determined by the average heat transfer coefficient of the fifth drying section. The above problems are solved by a film manufacturing method.

Another object of the present invention is to provide a method for producing a film using the above film producing apparatus, wherein the average drying temperature of the second drying section is equal to or higher than the average drying temperature of the first drying section. In addition, the present invention is solved by a film manufacturing method, wherein the average heat transfer coefficient of the second drying section is equal to or more than the average heat transfer coefficient of the first drying section.

In addition, another object of the present invention is to provide a method of manufacturing a film using the above-described film manufacturing apparatus, wherein the average drying temperature of the fifth drying section is equal to or higher than the average drying temperature of the fourth drying section. And / or) The film manufacturing method is characterized in that the average heat transfer coefficient of the fifth drying section is equal to or higher than the average heat transfer coefficient of the fourth drying section.

Another object of the present invention is to provide a method of manufacturing a film using the above-described film manufacturing apparatus, wherein the cooling temperature of the cooling section is set lower than any of the first to fifth drying sections. The problem is solved by a film manufacturing method characterized by the following.

Still another object of the present invention is to provide a method of manufacturing a film using the above-described film manufacturing apparatus, wherein the cooling temperature of the cooling processing section is set to 3 ° C. or more and 20 ° C. or less. Solved by the method.

In the above-mentioned film manufacturing apparatus, the second drying treatment section can be configured so that the support heats the web by increasing the temperature of the support using hot water.

Further, in the same film manufacturing apparatus, a new web layer is formed on the web during the drying process during the drying process in the first drying process section and the second drying process section. It is preferable to further comprise a second dope casting means.

The film manufacturing apparatus is located at a position opposite to one of the drums as a third drying section with the support interposed therebetween, and heats the web on the support.
It is preferable to further comprise a drying section.

The dope used in the film production method (film production apparatus) of the present invention comprises at least a solvent and a lower fatty acid ester cotton, and the lower fatty acid ester cotton is linter 10 to 10
One consisting of 0 parts by weight and 90 to 0 parts by weight of pulp (the total of linter and pulp is 100 parts by weight) can be mentioned.

As the dope used in the film production method (film production apparatus) of the present invention, at least one of a plasticizer of a phosphate ester type, a phthalate ester type and a glycolate type comprises a lower fatty acid. What added by 2-20% by weight ratio with respect to ester cotton can be mentioned.

Furthermore, as the dope used in the process of film production the present invention (Film manufacturing apparatus), so that the benzotriazole ultraviolet absorber is present 0.5~3.0g per web 1 m ^2, the benzotriazole Examples thereof include those obtained by adding an ultraviolet absorber.

[0026] In addition, as the dope used in the process of film production the present invention (Film manufacturing apparatus), fine particles of silicon dioxide web 1 m ² per 0.02
g can be exemplified by the addition of the silicon dioxide fine particles so as to be present.

The dope used in the film production method (film production apparatus) of the present invention comprises at least a solvent and a lower fatty acid ester cotton, and the amount of the solvent in the dope (cm ³ ) / lower fatty acid ester cotton. The thing whose value of weight (g) is 2.0 or more and 4.5 or less can be mentioned.

Further, the solvent for forming the dope used in the film production method (film production apparatus) of the present invention includes a first solvent having a dissolving ability for lower fatty acid ester cotton and the lower fatty acid Examples thereof include those comprising a second solvent having no dissolving ability with respect to the ester cotton. Particularly, when the total weight of the solvent remaining in the film is 4% or less of the weight of the film in the absolute dry state, It is preferable that the ratio of the second solvent to the remaining solvent is not more than 1/2.

As the film which is the object of the film manufacturing method (film manufacturing apparatus) of the present invention, there can be particularly mentioned a polarizing plate protective film.

As described above, in the present invention, particularly in the invention relating to the film production method, the drying time of the web in a state where the web is in contact with the support is set to 0.3 to 2 times.
In addition to 0 min, the temperature of the gas blown to the web in contact with the support and the temperature of the contact surface of the support were 5 ° C or more and 100 ° C or less. Therefore, the web is dried on the support under extremely ideal conditions, and as a result, even when a thin film having a thickness of 20 to 85 μm is produced, curl occurs in the finally obtained film. The curl phenomenon can be effectively suppressed. That is, according to the film manufacturing method of the present invention, the thickness is 20 to 85 μm
High quality film can be obtained efficiently.

Further, in the invention relating to the film production apparatus, the section from the dope casting means to the peeling means includes:
First to fifth drying processing sections and a cooling processing section are provided, and the average drying temperature of the first drying processing section is equal to or higher than the average drying temperature of the fourth drying processing section, and / or , The average heat transfer coefficient of the first drying section is equal to or greater than the average heat transfer coefficient of the fourth drying section. Thus, in this case as well, the web is dried under very ideal conditions on the support, so that even if a thin film with a thickness of 20 to 85 μm is produced, the finally obtained film is obtained. The curl phenomenon that causes curl can be effectively suppressed. That is, with the film manufacturing apparatus of the present invention, a high-quality film having a thickness of 20 to 85 μm can be efficiently obtained.

Further, in the invention relating to the film manufacturing method, the average drying temperature of the second drying section is equal to or higher than the average drying temperature of the third drying section, and the average drying temperature of the third drying section is Was set to be equal to or higher than the average drying temperature of the fifth drying section. Alternatively, the average heat transfer coefficient of the second drying section was set to be equal to or greater than the average heat transfer coefficient of the fifth drying section.
Alternatively, the average drying temperature of the second drying section is equal to or higher than the average drying temperature of the first drying section, and / or the average heat transfer coefficient of the second drying section is the first drying Or higher than the average heat transfer coefficient of the part. Alternatively, the average drying temperature of the fifth drying section is equal to or higher than the average drying temperature of the fourth drying section, and / or the average heat transfer coefficient of the fifth drying section is the fourth drying section. Or higher than the average heat transfer coefficient of the part. Alternatively, the cooling temperature of the cooling processing unit was set lower than any of the first to fifth drying processing units. Alternatively, the cooling temperature of the cooling section was set to 3 ° C. or more and 20 ° C. or less.
Thus, in this case as well, the web is dried on the support under very ideal conditions, so that the thickness is between 20 and
Even when a thin film having a thickness of 85 μm is manufactured, the curl phenomenon in which the finally obtained film is curled can be effectively suppressed. That is, according to the film manufacturing method of the present invention, a high-quality film having a thickness of 20 to 85 μm can be efficiently obtained.

Now, although the above description partially overlaps the contents,
The film to which the production technique of the present invention is applied is, for example, a film composed of a cellulose ester, particularly a lower fatty acid ester of cellulose. Here, “lower” means that the number of carbon atoms is 6 or less, and specifically, for example, cellulose acetate such as cellulose diacetate and cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate Mixed fatty acid esters such as pionate and cellulose acetate butyrate are exemplified. Most preferred, however, is cellulose triacetate. Above all, the degree of acetylation is 54 ~
Cellulose triacetate with 62% and a degree of polymerization of 250 to 400 is particularly desirable.

Next, as a solvent constituting the dope, for example, alcohols (especially lower alcohols) such as methanol, ethanol, n-propyl alcohol, isopropyl alcohol and n-butanol, cyclohexane, dioxane, methylene chloride, etc. Aliphatic hydrocarbons and chlorides. Incidentally, the ratio of the solvent is preferably, for example, about 70 to 95% by weight for methylene chloride, and about 30 to 5% by weight for other solvents. Further, the concentration of the cellulose ester is preferably about 10 to 50% by weight.

The heating temperature after the addition of the solvent is preferably a temperature not lower than the boiling point of the solvent used and within a range where the solution does not boil, and is set, for example, to 60 ° C. or higher, particularly 80 to 110 ° C. The pressure is determined so that the solution does not boil at the set temperature. After dissolution, it is taken out of the container while cooling, or is taken out of the container by a pump or the like, cooled by a heat exchanger, and then subjected to filtration.

After filtering the dope composition in which the above-mentioned film constituting materials (for example, cellulose ester, plasticizer, ultraviolet absorber, matting agent, etc.) are dissolved in a solvent, the film is formed by a solution casting method, for example, to obtain cellulose. And a film having a thickness of 20 to 85 μm, which is produced by using the lower fatty acid ester of the present invention, to be produced by the present invention.

As a film production technique using the solution casting method, for example, US Pat. Nos. 2,492,978, 2,739,070, 2,739,069 and 2,492,977 No. 2,336,310, No. 2,367,603, No. 2,607,704, British Patent Nos. 64,071 and 735,892, Japanese Patent Publication No. 45
Nos. -9074, 49-4554, 49-5614
Nos. 60-27562, 61-39890 and 62-4208 can be referred to.

[0038]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention (film manufacturing method) will be described below in detail with reference to FIG. However,
FIG. 1 is a schematic diagram of an apparatus used to manufacture a film using the technology according to the present embodiment.

The film manufacturing method according to the present embodiment (hereinafter simply referred to as the present film manufacturing method) includes a solution casting method,
In particular, using a band casting method, the thickness is 20 μm or more,
This is a technique for producing a film having a thickness of less than 85 μm, particularly a polarizing plate protective film (hereinafter also referred to as a film used for a liquid crystal display member) (the same applies to other embodiments described later).

The film production operation according to the present film production method is performed using a film production apparatus whose overall structure is schematically shown in FIG. Here, the structure of the film manufacturing apparatus will be described.

The film production apparatus shown in FIG. 1 comprises a dope casting means 1, a circulating casting band (support) 2, a peeling roll (peeling means) 3, and a drying roll provided in two stages in the transport direction. The main components are boxes (drying means) 4 and 5, and a winding means 7 provided with a winding core 6 for winding the obtained film F. However, a tenter may be used as the drying means.

The dope casting means 1 includes a tank 8 having a stirring function, a liquid feed pump 9, and a casting solution for casting a dope, which is a raw material solution of the film F, onto the casting band 2. It has a die (hereinafter simply referred to as a die) 10. Thereby, the dope casting means 1 can cast the dope in the tank 8 from the die 10 onto the casting band 2 by a predetermined amount.

Here, the dope and the film used in the present film production method will be described. The dope used in the present film production method mainly comprises a solvent and lower fatty acid ester cotton, and the lower fatty acid ester cotton (100 parts by weight) comprises 10 to 100 parts by weight of linter and 90 to 0 parts by weight of pulp. . In addition, at least one plasticizer of a phosphate ester type, a phthalate ester type, or a glycolate type is added to the dope in a weight ratio of 2 to 20% with respect to the lower fatty acid ester cotton. In addition, the dope contains a benzotriazole-based UV absorber,
0.2 g / m ^{2 of} web formed using this dope.
It is added so that 5-3.0 g is present. In addition to the doped silicon dioxide fine particles have been added to existing 0.02~0.5g per web 1 m ² formed using this dope.

More specifically, the value of the amount of solvent (cm ³ ) / weight of lower fatty acid ester cotton (g) in the above dope is:
2.0 or more and 4.5 or less. The solvent forming the dope is composed of a first solvent having a dissolving ability for lower fatty acid ester cotton and a second solvent having no dissolving ability. The film to be manufactured by the present film manufacturing method is such that the total weight of the solvent remaining in the film is 4% or less of the weight of the film in the absolutely dry state, and the second type of solvent occupies the remaining solvent. Is 以下 or less.

The dope preferably satisfies all of these conditions, but may satisfy only one of the conditions. Further, the dope is not limited to those meeting the above conditions, and any other dope may be used.

Incidentally, the dope described above is also used in other embodiments (film manufacturing method or film manufacturing apparatus) of the present invention described hereinafter. Also,
In the film to be manufactured by the technology of the other embodiment of the present invention described below, the total weight of the remaining solvent is 4% or less of the weight of the film in the absolutely dry state, and the remaining film is present. When the proportion of the second solvent in the solvent is 1/2
These are:

On the contrary, the casting belt 2 on which the dope is cast is an endless belt that circulates (circulates) as described above, and is stretched between the pair of drums 11a and 11b. A driving unit (not shown) is connected to one of the drums 11a and 11b.
By activating this driving means, the belt 2 is moved to the position shown in FIG.
Circulates in the direction of the arrow.

The peeling roll 3 provided in the vicinity of the belt 2 helps the web W formed on the surface of the belt 2 by the dope casting means 1 to be peeled from the belt 2. That is, the transport direction of the web W that has not been sufficiently dried and is still in a soft state is changed to the drying boxes 4 and 5 by the peeling tension and the action of the peeling roll 3.

The drying boxes 4 and 5 have the same structure. That is, a plurality of transport rolls 12 are provided vertically inside the interior. Therefore, the web W comes into close contact with the peripheral surface of the transport roll 12 and is transported by sewing between the webs. Further, the drying boxes 4 and 5 are adapted to be capable of introducing a drying air.

The winding means 7 is for winding the film F obtained through the drying boxes 4 and 5, and has the winding core 6 around which the film F is wound as described above. The take-up core 6 is connected to a drive unit (not shown). By operating the drive unit, the take-up core 6 rotates to wind the film F at a constant speed.

The procedure for manufacturing the film F using the film manufacturing apparatus configured as described above (namely, the present film manufacturing method) is as follows. First, a dope, which is a raw material solution of the film F, is cast from the casting die 10 onto the casting band 2, and a web (doped film) W having a uniform thickness is formed on the casting band 2. (Dope casting step). Next, the web W formed on the casting band 2 in the dope casting step is peeled from the circulating traveling belt 2 (peeling step), and further, the web W is dried and dried. Send it to Box 5. Then, the web W is completely dried while being transported through the plurality of transport rolls 12 in the drying boxes 4 and 5, and finally becomes a film F having a thickness of 20 to 85 μm (drying step). . Thereafter, the film F may be wound by the winding core 6 provided at the end of the production line (winding step).
Thereby, the film F becomes a winding roll (film winding body).

The web W is dried to a certain extent even in a state in which the web W is in contact with the casting band 2, that is, before the peeling step. In this web W
The drying time was 0.3 to 20 min. Further, dry air (gas) is supplied to the web W for drying in a state where the web W is in contact with the casting band 2. In the present film manufacturing method, the web W is in contact with the casting band 2. The temperature of the dry air blown to the web W and the temperature of the contact surface of the belt 2 were 5 ° C. or more and 100 ° C. or less.

Therefore, the web W is placed on the belt 2
The film F is dried under extremely ideal conditions. As a result, even when a thin film having a thickness of 20 to 85 μm is produced, the curl phenomenon in which curl occurs in the finally obtained film F can be effectively suppressed. . That is, according to the present film manufacturing method, a high-quality film having a thickness of 20 to 85 μm can be efficiently obtained.

Next, a second embodiment of the present invention (film manufacturing apparatus) will be described with reference to FIG. However, FIG. 2 is an enlarged view of a web forming portion in the film manufacturing apparatus according to the present embodiment. The overall structure of the film manufacturing apparatus, the basic process of manufacturing a film using the same, the composition of the dope to be used, and the like are the same as those of the first embodiment. So in the following,
The following description focuses on the differences from the first embodiment (the same applies to the third and subsequent embodiments).

The present film manufacturing apparatus is also for manufacturing a film having a thickness of 20 to 85 μm by using the solution casting method. As in the first embodiment, the dope casting means and the peeling means are used. , Drying means and winding means.

Although the peeling means, the drying means and the winding means are not shown in the drawing, the peeling means is a web (shown in the drawing) formed on the casting band (support) 22 by the dope casting means. ) Is removed from the belt 22, and the drying unit is used to dry the web separated from the belt 22 by the separating unit while transporting the web through a plurality of transport rolls. The winding means plays a role of winding the film obtained by drying the web by the drying means.

Next, the dope casting means provided with the die 21 is used for casting a dope, which is a raw material solution of a film, onto the casting band 22. In this embodiment, In a section from the dope casting means to the stripping means, first to sixth drying processing units O to T and a cooling processing unit U described in detail below are provided.

The first drying section O has a function of blowing gas onto the web formed on the belt 22 by the dope casting means. Next, the second drying processing unit P sandwiches the belt 22 with the first drying processing unit O.
And plays a role in heating the web via the belt 22. Further, the third drying section Q
Is present downstream of the first drying section O and the second drying section P, but here, as the third drying section Q, the casting band 22 is circulated. One of the drums 23 constituting a pair of drums to be driven is used. The drum 23 as the third drying section Q is
The web is heated via the belt 22.

Next, the fourth drying section R is present downstream of the third drying section Q and plays a role of blowing gas onto the web. Further, the fifth drying processing unit S
The web exists at a position facing the fourth drying section R with the belt 22 interposed therebetween, and heats the web via the belt 22. The sixth drying section T is located at a position opposite to the drum 23 on the one side serving as the third drying section Q with the belt 22 interposed therebetween.
2 serves to heat the web.

Further, the cooling processing unit U is provided downstream of the fourth drying processing unit R and the fifth drying processing unit S, and has a function of cooling the web via the belt 22. Have. However, here, as the cooling processing unit U,
A drum 24 on the other side which forms a pair of drums for circulating the belt 22 is used. That is, the drum 24 serving as the cooling unit U cools the web via the belt 22.

In this embodiment, the first drying unit O
Is equal to or higher than the average drying temperature of the fourth drying section R, and the average heat transfer coefficient of the first drying section O is equal to or higher than the average heat transfer coefficient of the fourth drying section R. It is configured as follows. However, simply setting the average drying temperature of the first drying processing unit O to be equal to or higher than the average drying temperature of the fourth drying processing unit R, or setting the average heat transfer coefficient of the first drying processing unit O to the fourth drying temperature Only the average heat transfer coefficient of the processing unit R may be equal to or more than the average heat transfer coefficient.

In this embodiment, in particular, in the first drying section O
The drying temperature decreases stepwise (or continuously) from the upstream side to the downstream side along the running direction of the belt 22, and the heat transfer coefficient of the first drying section O decreases. Also, it is configured to gradually (or continuously) decrease from the upstream side to the downstream side along the running direction of the belt 22. However, the first drying unit O
The drying temperature of the first drying processing unit O can be reduced only stepwise (or continuously) from the upstream side to the downstream side along the running direction of the belt 22 in the running direction.
May be decreased stepwise (or continuously) from the upstream side to the downstream side along the running direction of the belt 22.

Further, in the present embodiment, the fourth drying section R
Also, the drying temperature decreases stepwise (or continuously) from the upstream side to the downstream side along the running direction of the belt 22 and the transmission temperature of the fourth drying section R increases. The heat coefficient is configured to decrease stepwise (or continuously) from the upstream side to the downstream side along the traveling direction of the belt 22. However, even if the drying temperature of the fourth drying section R is decreased stepwise (or continuously) from the upstream side to the downstream side along the running direction of the belt 22, The heat transfer coefficient of the drying section R may be reduced stepwise (or continuously) from the upstream side to the downstream side along the running direction of the belt 22.

In the second drying section P, the temperature of the belt 22 is raised by using hot water. As a result, the web is heated via the belt 22. .

Even in the film manufacturing apparatus configured as described above, the web is dried on the belt 22 under extremely ideal conditions. As a result, the thickness is 20 to
Even when a thin film having a thickness of 85 μm is manufactured, the curl phenomenon in which the finally obtained film is curled can be effectively suppressed. That is, even with the present film manufacturing apparatus, a high-quality film having a thickness of 20 to 85 μm can be efficiently obtained.

Next, a third embodiment of the present invention (film manufacturing method) will be described. This film production method
This is carried out using the film manufacturing apparatus described above as the second embodiment of the present invention, and also includes a dope casting step, a peeling step, a drying step, and a winding step.
Then, in the present film manufacturing method, the second drying section P
The average drying temperature of the third drying section Q is equal to or higher than the average drying temperature of the third drying section Q, and the average drying temperature of the third drying section Q is equal to or higher than the average drying temperature of the fifth drying section S. It is characterized by.

Accordingly, the web was dried under extremely ideal conditions on the casting band 22, so that even if a thin film having a thickness of 20 to 85 μm was produced, it was finally obtained. It is possible to effectively suppress the curl phenomenon in which the film is curled. That is, according to the present film manufacturing method, it is possible to efficiently obtain a high-quality film having a thickness of 20 to 85 μm (the same effect is obtained in other embodiments described hereinafter). .

Next, a fourth embodiment of the present invention (film manufacturing method) will be described. This film production method also
It is carried out using the film manufacturing apparatus described as the second embodiment of the present invention, and includes a dope casting step, a peeling step, a drying step, and a winding step as main steps. Then, in the present film manufacturing method, the average heat transfer coefficient of the second drying section P is calculated by the fifth drying section S.
The average heat transfer coefficient is not less than the average heat transfer coefficient.

Next, the fifth method of the present invention (film production method)
An embodiment will be described. This film manufacturing method is also performed using the film manufacturing apparatus described as the second embodiment of the present invention, and includes a dope casting step, a peeling step, a drying step, and a winding step. In the present film manufacturing method, the average drying temperature of the second drying section P is equal to or higher than the average drying temperature of the first drying section O, and the average heat transfer coefficient of the second drying section P is , The average heat transfer coefficient of the first drying section O or more.
However, depending on the case, the average drying temperature of the second drying section P may be simply set to be equal to or higher than the average drying temperature of the first drying section O, or the average heat transfer coefficient of the second drying section P may be reduced. Alternatively, only the average heat transfer coefficient of the first drying section O may be set to be equal to or higher than the average.

Subsequently, the present invention (film production method)
The sixth embodiment will be described. This film manufacturing method is also carried out using the film manufacturing apparatus described as the second embodiment of the present invention, and a dope casting step,
A peeling step, a drying step, and a winding step are provided. Then, in the present film manufacturing method, the average drying temperature of the fifth drying section S is equal to or higher than the average drying temperature of the fourth drying section R, and the average heat transfer coefficient of the fifth drying section S is , And not less than the average heat transfer coefficient of the fourth drying section R. However, depending on the case, the average drying temperature of the fifth drying section S may be simply set to be equal to or higher than the average drying temperature of the fourth drying section R, or the average heat transfer coefficient of the fifth drying section S may be reduced. Alternatively, it may be just the average heat transfer coefficient of the fourth drying section R or more.

Next, the seventh (film manufacturing method) of the present invention
An embodiment will be described. This film manufacturing method is also performed using the film manufacturing apparatus described as the second embodiment of the present invention, and includes a dope casting step, a peeling step, a drying step, and a winding step. And in this film manufacturing method, the cooling temperature of the cooling processing unit U is set higher than any of the drying temperatures of the first to sixth drying processing units O to T, in particular, the first to fifth drying processing units O to S. It is characterized by being lowered.

Subsequently, the present invention (film production method)
An eighth embodiment will be described. This film manufacturing method is also carried out using the film manufacturing apparatus described as the second embodiment of the present invention, and a dope casting step,
A peeling step, a drying step, and a winding step are provided. And in this film manufacturing method, the cooling temperature of the cooling processing unit U is
It is characterized by a temperature of 3 ° C. or more and 20 ° C. or less.

Next, a ninth embodiment of the present invention (film manufacturing apparatus) will be described with reference to FIG. However, FIG. 3 is an enlarged view of a main part of the film manufacturing apparatus according to the present embodiment. The overall structure of the present film manufacturing apparatus is the same as that of the second embodiment described in detail above.
Therefore, only the differences from the second embodiment (that is, the main parts of the present embodiment) will be described below.

The present film manufacturing apparatus also includes, as basic components, a dope casting means having a die 31 and a casting band 3.
2, and peeling roll, drying box, not shown,
And it has winding means. Further, in addition to this, in the present embodiment, a second dope casting means having a die 33 is provided.

In the course of the drying process in the first drying section O and the second drying section P shown by the dashed line in FIG. (Web formed by the dope casting means having the die 31) On the W, plays a role of forming a new web layer W '. As a result, in the present film manufacturing apparatus having two dope casting units, higher quality can be realized as compared with the case where the web is formed using one dope casting unit. That is, the occurrence of curl in the film is more effectively suppressed.

Here, for reference, a liquid crystal display member, for example, a polarizing plate, comprising a film obtained by using the technique of the present embodiment as a component is manufactured as follows. First, iodine or the like is adsorbed on a polymer film, and the above-mentioned film which has been subjected to an alkali treatment is attached to both sides of a stretched polarizer using a completely saponified polyvinyl alcohol aqueous solution. Thereby, the polarizing plate is obtained. However, instead of the alkali treatment, a method disclosed in JP-A-6-94915 or JP-A-6-118232 may be adopted.

Incidentally, the “liquid crystal display member” in this specification refers to a member used in a liquid crystal display device. For example, in addition to the polarizing plate, a polarizing plate protective film, a retardation plate, a reflector, a viewing angle improving film, an anti-glare film,
Non-reflective films, antistatic films and the like can be mentioned. In addition, it is also used for an optical film useful for an organic electroluminescence display.

[0078]

According to the present invention, the thickness is 20 to 85 μm.
High quality film can be obtained efficiently. In particular, when a film having a thickness of 20 to 85 μm is produced, the curl phenomenon in which curl occurs in the obtained film can be effectively suppressed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an apparatus used to manufacture a film using a film manufacturing method according to a first embodiment of the present invention.

FIG. 2 is an enlarged view of a web forming portion in a film manufacturing apparatus according to a second embodiment of the present invention.

FIG. 3 is an enlarged view of a main part of a film manufacturing apparatus according to a ninth embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 dope casting means 2 casting band (support) 3 peeling roll (peeling means) 4, 5 drying box (drying means) 6 take-up core 7 take-up means 8 tank 9 liquid feed pump 10 casting dies 11a, 11b Drum 12 Conveyance roll W Web (doped film) F film

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F205 AA01 AB14 AB17 AB22 AB23 AH73 GA07 GB02 GC08 GE12 GE22 GE24 GF03 GF24 GN13 GW06 GW15

Claims (27)

[Claims] 1. A thickness of 20 to 8 using a solution casting method.
A method for producing a 5 μm film, comprising: a dope casting step of casting a dope, which is a raw material solution of the film, from a die on a support; and a dope casting step on the support in the dope casting step. A peeling step of peeling the formed web from the support; and a drying step of drying the web peeled from the support in the peeling step while transporting the web through a plurality of transport rolls. And a winding step of winding a film obtained by drying the web in a drying step, in a state where the web is in contact with the support, a drying time of the web is 0.3 to 20 minutes, and the temperature of the gas blown onto the web in contact with the support and the temperature of the contact surface of the support are 5 ° C or more and 100 ° C or less. Irumu manufacturing method. 2. A thickness of 20 to 8 using a solution casting method.
An apparatus for producing a 5 μm film, comprising: a dope casting means provided with a die for casting a dope, which is a raw material solution of the film, on a support; Peeling means for peeling the web formed thereon from the support; drying means for drying the web peeled from the support by the peeling means while transporting the web through a plurality of transport rolls; A winding means for winding a film obtained by drying the web by the drying means, and further, a section from the dope casting means to the peeling means is provided by the dope casting means. A first drying section for blowing a gas to the web formed on the support; and a first drying section facing the first drying section across the support. A second drying unit that heats the web via the support, and a pair of drums that are provided following the first drying unit and the second drying unit and circulate the support. A drum on one side, which is a third drying unit for heating the web via the support, and a second drum that is provided subsequent to the third drying unit and blows a gas onto the web. A fourth drying processing unit, a fifth drying processing unit that is located at a position facing the fourth drying processing unit with the support interposed therebetween, and heats the web via the support; A cooling processing unit for cooling the web via the support, which constitutes a pair of drums that is provided subsequent to the drying processing unit and the fifth drying processing unit and circulates and runs the support. And a drum on the side The average drying temperature of the first drying section is equal to or higher than the average drying temperature of the fourth drying section, and / or the average heat transfer coefficient of the first drying section is the fourth drying section. An apparatus for producing a film, wherein the apparatus is configured to have an average heat transfer coefficient equal to or higher than the average heat transfer coefficient of the processing section. 3. The drying temperature of the first drying section decreases from the upstream side to the downstream side along the direction of travel of the support, and / or the drying temperature of the first drying section decreases. The film manufacturing apparatus according to claim 2, wherein the heat coefficient is configured to decrease from an upstream side to a downstream side along the support running direction. 4. The drying temperature of the fourth drying section decreases from the upstream side to the downstream side along the direction of travel of the support, and / or the transmission temperature of the fourth drying section decreases. The film manufacturing apparatus according to claim 2, wherein a thermal coefficient is configured to decrease from an upstream side to a downstream side along the support running direction. 5. 5. A method for producing a film using the film production apparatus according to claim 2, wherein the average drying temperature of the second drying section is set to a third drying temperature. The film manufacturing method, wherein the average drying temperature of the third drying section is equal to or higher than the average drying temperature of the fifth drying section. 6. A film manufacturing method using the film manufacturing apparatus according to any one of claims 2 to 4, wherein an average heat transfer coefficient of the second drying section is set to a fifth drying coefficient. A method for producing a film, wherein the average heat transfer coefficient is equal to or higher than the average heat transfer coefficient of the processing section. 7. A method for producing a film using the film production apparatus according to any one of claims 2 to 4, wherein the average drying temperature of the second drying section is set to the first drying processing. Wherein the average heat transfer coefficient of the second drying section is equal to or higher than the average heat transfer coefficient of the first drying section. . 8. A method for producing a film using the film production apparatus according to claim 2, wherein the average drying temperature of the fifth drying section is set to a fourth drying temperature. Wherein the average heat transfer coefficient of the fifth drying section is equal to or higher than the average heat transfer coefficient of the fourth drying section. . 9. A method of manufacturing a film using the film manufacturing apparatus according to claim 2, wherein the cooling temperature of the cooling processing unit is set to a first to fifth drying processing units. Wherein the drying temperature is lower than the drying temperature. 10. The second drying section, wherein the support is configured to heat the web by increasing the temperature of the support using hot water. Item 5. A film production apparatus according to any one of Items 4. 11. The above-mentioned claims 2 to 4, and 10
A film manufacturing method using the film manufacturing apparatus according to any one of claims 1 to 3, wherein a cooling temperature of the cooling processing unit is set to 3 ° C or more and 20 ° C or less. 12. During the drying process in the first drying process unit and the second drying process unit, on the web during the drying process,
The film production apparatus according to any one of claims 2 to 4, further comprising a second dope casting means for forming a new web layer. 13. A sixth drying processing unit which is located at a position opposite to a drum on one side as a third drying processing unit with the support interposed therebetween and heats a web on the support. Claim 2 to Claim 4, Claim 1
The film manufacturing apparatus according to any one of claims 1 to 12. 14. The dope comprises at least a solvent and a lower fatty acid ester cotton, and the lower fatty acid ester cotton comprises 10 to 100 parts by weight of linter and 90 to 100 parts by weight of pulp.
The film production method according to any one of claims 1, 5 to 9, and 11, comprising 0 parts by weight. 15. The dope comprises at least a solvent and a lower fatty acid ester cotton, and the lower fatty acid ester cotton comprises 10 to 100 parts by weight of linter and 90 to 100 parts by weight of pulp.
The film production apparatus according to any one of claims 2 to 4, claim 10, claim 12, or claim 13, comprising 0 parts by weight. 16. The dope includes at least one of a phosphate ester, a phthalate, and a glycolate.
15. The plasticizer according to claim 1, wherein the plasticizer is added in an amount of 2 to 20% by weight relative to the lower fatty acid ester cotton. Film manufacturing method. 17. The dope includes at least one of a phosphate ester type, a phthalate ester type, and a glycolate type.
3. The composition according to claim 2, wherein the plasticizer is added in an amount of 2 to 20% by weight based on the weight of the lower fatty acid ester cotton.
The film manufacturing apparatus according to any one of claims 1 to 4, claim 10, claim 12, claim 13, and claim 15. 18. As the benzotriazole ultraviolet absorber is present 0.5~3.0g per web 1 m ^2, the doping claims, characterized in that the benzotriazole-based ultraviolet absorber is formed by adding 1, Claim 5
The film production method according to any one of claims 9, 11, 14, and 16. 19. As the benzotriazole ultraviolet absorber is present 0.5~3.0g per web 1 m ^2, the doping claims, characterized in that the benzotriazole-based ultraviolet absorber is formed by adding The film manufacturing apparatus according to any one of claims 2 to 4, claim 10, claim 12, claim 13, claim 15, or claim 17. 20. The dope is added with the silicon dioxide fine particles so that 0.02 to 0.5 g of the silicon dioxide fine particles are present per 1 m ^{2 of the} web. The method for producing a film according to any one of claims 9, 11, 14, 16, and 18. 21. The dope is added with the silicon dioxide fine particles so that the fine particles of silicon dioxide are present in an amount of 0.02 to 0.5 g per 1 m ^{2 of the} web. Claim 10, Claim 12, Claim 1
The film manufacturing apparatus according to any one of claims 15, 15, 17, and 19. 22. The dope is composed of at least a solvent and lower fatty acid ester cotton, and the value of solvent amount (cm ³ ) / lower fatty acid ester cotton weight (g) in the dope is 2.0 or more and 4.5. The film manufacturing method according to any one of claims 1, 5 to 9, 11, 11, 14, 16, 18, and 20, wherein: 23. The dope is composed of at least a solvent and a lower fatty acid ester cotton, and a value of solvent amount (cm ³ ) / lower fatty acid ester cotton weight (g) in the dope is 2.0 or more and 4.5. Claims 2 to 4, Claim 10, Claim 12, Claim 13, Claim 15, Claim 17, Claim 19, Claim 19, Claim 2
2. The film manufacturing apparatus according to any one of 1. 24. A solvent that forms a dope includes a first solvent having a solubility in lower fatty acid ester cotton and a second solvent having no solubility in the lower fatty acid ester cotton.
And the total weight of solvent remaining in the film is less than 4% of the weight of the film in the dry state,
The ratio of the second type solvent to the remaining solvent is not more than 1/2, wherein the ratio of the second type solvent is 1/2 or less. The film manufacturing method according to any one of claims 18, 20, and 22. 25. A solvent for forming a dope includes a first solvent having a dissolving ability for lower fatty acid ester cotton and a second solvent having no dissolving ability for the lower fatty acid ester cotton.
And the total weight of the solvent remaining in the film is less than 4% of the weight of the film in the dry state,
The ratio of the second type solvent to the remaining solvent is not more than 1/2, wherein the ratio of the second type solvent is 1/2 or less. Claim 15, Claim 17, Claim 19, Claim 21, Claim 2
3. The film production apparatus according to any one of 3. 26. The film according to claim 1, wherein the film is a polarizing plate protective film.
1, Claim 14, Claim 16, Claim 18, Claim 2
25. The method for producing a film according to any one of claims 22 to 24. 27. The method according to claim 2, wherein the film is a polarizing plate protective film.
The film manufacturing apparatus according to any one of claims 12, 13, 13, 15, 17, 19, 21, 23, and 25.