JP6911863B2 - Optical film manufacturing method - Google Patents

Description

The present invention relates to a method for producing an optical film for forming an optical film by a solution salivation film forming method, and particularly to agitation of a dope spreading on a support.

Conventionally, as a stirring device for stirring a solution, for example, there is one disclosed in Patent Document 1. In this stirring device, the first flat plate blade member and the second flat plate blade member are attached side by side along the rotation axis direction to the rotating shaft extending in the vertical direction in the stirring tank into which the solution is charged. The first flat plate blade member and the second flat plate blade member are attached to the rotating shaft at an inclination angle that raises the solution based on the rotation of the rotating shaft. By rotating such a first flat plate blade member and a second flat plate blade member about a rotation axis, a circulating flow of the solution is generated without being divided in the vertical direction of the stirring tank, and the solution is efficiently circulated up and down. It is possible to mix.

JP-A-2010-42337 (see claim 1, paragraphs [0001], [0004], [0007], FIGS. 1, 2, etc.)

However, the stirrer of Patent Document 1 was applied to the stirring of the resin and the solvent when preparing the dope used in the solution casting film forming method, and the optical film was formed by using the dope prepared by stirring. However, it was confirmed that the optical film had uneven film thickness and foreign matter with bright spots. The inventors of the present application speculate about these causes as follows.

Since both the first flat plate blade member and the second flat plate blade member of the stirring device are composed of stirring blades that generate upstream and downstream, even if stirring can be performed by circulation in the vertical direction, in the vertical direction. Stirring in the vertical direction (horizontal direction, shear direction) cannot be performed efficiently. As a result, the stirring in the stirring tank becomes uneven, and the dope viscosity becomes unstable due to the stirring unevenness, and the optical film formed by using such a dope has an uneven film thickness. Further, when stirring unevenness occurs, dissolution defects such as resin agglomeration in the stirring tank to form agglomerates (undissolved matter) occur. When an optical film is formed using a dope containing an undissolved substance, the above-mentioned undissolved substance appears as a bright spot foreign substance in the optical film.

In particular, when a pellet-shaped resin having a small specific gravity (for example, an acrylic resin) is dissolved in a solvent having a large specific gravity (for example, methylene chloride), the resin easily floats on the liquid surface and splices are generated, which is described above. As a result of the splicing powder remaining as an undissolved substance due to uneven stirring, bright spot foreign matter is likely to occur in the film-formed optical film.

The present invention has been made to solve the above problems, and an object of the present invention is to reduce uneven stirring in a stirring tank, thereby reducing uneven film thickness and foreign matter in bright spots of an optical film formed. It is an object of the present invention to provide a method for producing an optical film capable of reducing the occurrence of the above.

The above object of the present invention is achieved by the following manufacturing method.

That is, the method for producing an optical film according to one aspect of the present invention is a method for producing an optical film by a solution casting film forming method.
A stirring preparation step of preparing a dope by stirring at least the resin and the solvent in a stirring tank, and
Including a casting step of casting the dope prepared in the stirring preparation step on the support.
The resin is any one of an acrylic resin, a cycloolefin resin, and a polyarylate resin.
When the specific gravity of the resin is A, the specific gravity of the solvent is B, and the specific gravity difference (BA) is Δ,
0.1 <Δ <0.5
And
The stirring tank is provided with a first stirring jig and a second stirring jig.
The first stirring jig is formed in the stirring tank from a first rotating shaft located on a vertical axis passing through the center of the bottom surface of the stirring tank and a lowermost portion of the first rotating shaft. It has an arm portion that is located above the lowermost portion and extends to a position separated from the first rotation axis in the direction of the radius of gyration.
The second stirring jig is aligned with the second rotating shaft extending in the vertical direction so as to pass through the space between the first rotating shaft and the arm portion. It has at least two stirring blades attached to two rotating shafts and has
Let L be the length of the arm of the first stirring jig along the vertical direction, and of the at least two stirring blades of the second stirring jig, the uppermost stirring blade and one below the stirring blade. When the stirring blades located in are the first stirring blade and the second stirring blade, respectively,
The first stirring blade is located above the first stirring jig, including a position vertically lowered by (1/3) L from the uppermost portion of the arm portion of the first stirring jig, and is located above the second stirring blade. It is composed of a stirring blade that causes the vertical flow of the resin by rotation around the rotation axis of the above.
The second stirring blade is located below the position where the first stirring jig is vertically lowered by (1/3) L from the uppermost portion of the arm portion of the first stirring jig, and the second rotation axis is formed. It is composed of a stirring blade that causes a flow of the resin vertically downward by the first stirring blade due to rotation around the center in a direction perpendicular to the second rotation axis.

According to the above manufacturing method, it is possible to reduce the uneven stirring in the stirring tank, thereby reducing the uneven film thickness of the optical film formed and the generation of bright spot foreign matter.

It is explanatory drawing which shows the schematic structure of the optical film manufacturing apparatus which concerns on embodiment of this invention. It is a flowchart which shows the flow of the manufacturing process of the said optical film. It is sectional drawing which shows typically an example of the stirring apparatus which has the 1st stirring jig. It is sectional drawing which shows the other structure of the said 1st stirring jig. It is a perspective view which shows the other structure of the 1st stirring jig. It is a perspective view which shows the other structure of the 1st stirring jig. It is a perspective view which shows the other structure of the 1st stirring jig. It is a perspective view which shows the structural example of the 1st stirring blade of the 2nd stirring jig which the stirrer has. It is a perspective view which shows the other structural example of the said 1st stirring blade. It is a perspective view which shows the structural example of the 2nd stirring blade of the 2nd stirring jig. It is a perspective view which shows the other structural example of the 2nd stirring blade. It is sectional drawing which shows the other structure of the 2nd stirring jig. It is sectional drawing which shows the structural example of the stirring apparatus used in an Example. It is sectional drawing which shows the other structural example of the said stirring apparatus. It is sectional drawing which shows the further structural example of the said stirrer. It is sectional drawing which shows the further structural example of the said stirrer. It is sectional drawing which shows the further structural example of the said stirrer. It is sectional drawing which shows the further structural example of the said stirrer.

An embodiment of the present invention will be described below with reference to the drawings. In this specification, when the numerical range is expressed as A to B, the numerical range includes the values of the lower limit A and the upper limit B.

[Manufacturing method of optical film]
FIG. 1 is an explanatory diagram showing a schematic configuration of the optical film manufacturing apparatus 1 of the present embodiment. Further, FIG. 2 is a flowchart showing the flow of the manufacturing process of the optical film. The method for producing an optical film of the present embodiment is a method for producing an optical film by a solution casting film forming method, and as shown in FIG. 2, a stirring preparation step (S1), a casting step (S2), and a peeling step. (S3), stretching step (S4), drying step (S5), cutting step (S6), embossing step (S7), winding step (S8) are included. Hereinafter, each step will be described with reference to FIGS. 1 and 2.

<Stirring preparation process>
In the stirring preparation step, at least the resin and the solvent are stirred in the stirring tank 101 of the stirring device 100 to prepare a dope that is cast on the support 3 (endless belt). The details of the stirring device 100 will be described later.

<Cushion process>
In the casting step, the dope prepared in the stirring preparation step is sent to the casting die 2 by a conduit through a pressurized metering gear pump or the like, and is transferred infinitely on the support 3 made of a rotary drive stainless steel endless belt. The dope is cast from the casting die 2 at the casting position, thereby forming the web 5 as a casting film on the support 3.

The support 3 is held by a pair of rolls 3a and 3b and a plurality of rolls (not shown) located between them. One or both of the rolls 3a and 3b is provided with a driving device (not shown) for applying tension to the support 3, whereby the support 3 is used in a tensioned state.

In the casting step, the web 5 formed by the dope cast on the support 3 is heated on the support 3, and the solvent is evaporated from the support 3 until the web 5 can be peeled by the peeling roll 4. Let me. To evaporate the solvent, there are a method of blowing wind from the web side, a method of transferring heat from the back surface of the support 3 with a liquid, a method of transferring heat from the front and back surfaces by radiant heat, and the like, which are used individually or in combination as appropriate. Just do it.

<Peeling process>
In the above casting step, the web 5 is dried and solidified or cooled and solidified on the support 3 until the film strength becomes peelable, and then in the peeling step, the web 5 is peeled while maintaining self-supporting property. It is peeled off by the roll 4.

The amount of residual solvent of the web 5 on the support 3 at the time of peeling is preferably in the range of 50 to 120% by mass depending on the strength of the drying conditions, the length of the support 3, and the like. When peeling at a time when the amount of residual solvent is larger, if the web 5 is too soft, the flatness at the time of peeling is impaired, and wrinkles and vertical streaks are likely to occur due to the peeling tension. The amount of solvent is determined. The amount of residual solvent is defined by the following formula.

Residual solvent amount (mass%) = (mass before heat treatment of web-mass after heat treatment of web) / (mass after heat treatment of web) x 100
Here, the heat treatment for measuring the amount of residual solvent means that the heat treatment is performed at 115 ° C. for 1 hour.

<Stretching process>
In the stretching step, the web 5 peeled from the support 3 is stretched by the tenter 6. The stretching direction at this time is one of a film transport direction (MD direction; Machine Direction), a width direction (TD direction; Transverse Direction) perpendicular to the transport direction in the film plane, and both of these directions. In the stretching step, a tenter method in which both side edges of the web 5 are fixed with clips or the like and stretched is preferable in order to improve the flatness and dimensional stability of the film. In the tenter 6, drying may be performed in addition to stretching. In the stretching step, by stretching the web 5 in both the MD direction and the TD direction, the web 5 can be stretched (diagonally stretched) in a direction diagonally intersecting the MD direction and the TD direction.

(Drying process)
The web 5 stretched by the tenter 6 is dried by the drying device 7. In the drying device 7, the web 5 is conveyed by a plurality of conveying rolls arranged in a staggered pattern when viewed from the side surface, and the web 5 is dried between them. The drying method in the drying device 7 is not particularly limited, and generally, the web 5 is dried using hot air, infrared rays, a heating roll, microwaves, or the like. From the viewpoint of simplicity, a method of drying the web 5 with hot air is preferable.

The web 5 is dried by the drying device 7 and then conveyed as an optical film F toward the winding device 10.

(Cutting process, embossing process)
A cutting portion 8 and an embossing portion 9 are arranged in this order between the drying device 7 and the winding device 10. In the cutting portion 8, a cutting step is performed in which both ends in the width direction are cut by a slitter while conveying the formed optical film F. In the optical film F, the portion remaining after cutting both ends constitutes a product portion to be a film product. On the other hand, the portion cut from the optical film F is recovered by a shooter and reused as a part of the raw material for film formation.

After the cutting step, both ends of the optical film F in the width direction are embossed (knurled) by the embossing portion 9. The embossing process is performed by pressing a heated embossing roller against both ends of the optical film F. Fine irregularities are formed on the surface of the embossing roller, and by pressing the embossing roller against both ends of the optical film F, the irregularities are formed on both ends. By such embossing, winding misalignment and blocking (sticking between films) in the next winding process can be suppressed as much as possible.

(Winding process)
Finally, the optical film F having been embossed is wound by the winding device 10 to obtain the original winding (film roll) of the optical film F. That is, in the winding step, a film roll is manufactured by winding the optical film F around the winding core while conveying it. As the winding method of the optical film F, a commonly used winder may be used, and there are methods for controlling the tension such as a constant torque method, a constant tension method, a taper tension method, and a program tension control method with a constant internal stress. You can use them properly. The winding length of the optical film F is preferably 1000 to 7200 m. Further, the width at that time is preferably 1000 to 3200 mm, and the film thickness is preferably 10 to 60 μm.

[About the stirrer]
Next, the stirring device 100 used in the stirring preparation step described above will be described. FIG. 3 is a cross-sectional view schematically showing an example of the stirring device 100. The stirring tank 101 of the stirring device 100 is provided with a first stirring jig 111 and a second stirring jig 121. For convenience of explanation below, the bottom surface 101a side of the stirring tank 101 is referred to as "bottom", and the top surface 101b side is referred to as "top". The direction in which the bottom surface 101a and the top surface 101b face each other is the vertical direction (vertical direction), and the direction perpendicular to the vertical direction is the horizontal direction.

The first stirring jig 111 has a first rotating shaft 112 and an arm portion 113, and only one is provided in the stirring tank 101. The first rotating shaft 112 is located on the vertical axis AX passing through the center O of the bottom surface 101a of the stirring tank 101. The first rotation shaft 112 is connected to a drive source (for example, a motor) (not shown), and is rotated by driving the drive source. The rotation speed of the first rotation shaft 112 (= rotation speed of the first stirring jig 111) is appropriately adjusted in the range of, for example, 5 to 100 rpm.

The arm portion 113 is located above the lowermost portion 112a in the stirring tank 101 from the lowermost portion 112a, which is the lower tip portion of the first rotating shaft 112, and is located in the rotational radial direction (from the first rotating shaft 112). It is attached to the first rotating shaft 112 so as to extend to the uppermost portion 113a located at a position distant from the first rotating shaft 112 (in the direction perpendicular to the first rotating shaft 112). Further, two arm portions 113 are attached to the first rotating shaft 112 so as to be positioned symmetrically in a direction perpendicular to the first rotating shaft 112. The first rotation shaft 112 and each arm portion 113 may be integrally formed or may be formed by joining different members. Each arm 113 has a U-shaped cross section that is convex downward as a result of being curved and monotonically extending upward from the lowermost portion 112a of the first rotation shaft 112. The first stirring jig 111 having the above configuration is also called an anchor type because it looks like an anchor (anchor) in appearance.

FIG. 4 is a cross-sectional view showing another configuration of the first stirring jig 111. Each arm 113 of the first stirring jig 111 may have a W-shaped cross section as a whole. That is, each arm portion 113 may have a shape that once descends from the lowermost portion 112a of the first rotation shaft 112 toward the outside in the radial direction of rotation and extends from there toward the uppermost portion 113a. Such a first stirring jig 111 is also a kind of anchor type.

5 to 7 are perspective views showing still another configuration of the first stirring jig 111. As shown in FIG. 5, the first stirring jig 111 is configured to have an arm portion 113 having a shape that extends outward in the radial direction from the lowermost portion of the first rotating shaft 112 and then bends upward. You may. Such a first stirring jig 111 is also a kind of anchor type. Further, as shown in FIGS. 6 and 7, the first stirring jig 111 is composed of a so-called anchor paddle type in which the area of the arm portion 113 is increased to improve the efficiency of stirring (web). You may be.

The second stirring jig 121 shown in FIG. 3 has a second rotating shaft 122 and at least two stirring blades 123. In the present embodiment, two second stirring jigs 121 are provided in the stirring tank 101, and are located on opposite sides of the first rotating shaft 112 of the first stirring jig 111. There is.

The second rotating shaft 122 of the second stirring jig 121 extends in the vertical direction so as to pass through the space between the first rotating shaft 112 of the first stirring jig 111 and the arm portion 113. That is, the first rotation axis 112 and the second rotation axis 122 are parallel to each other. The second rotation shaft 122 is connected to a drive source (for example, a motor) (not shown), and is rotated by driving the drive source. The rotation speed of the second rotation shaft 122 (= rotation speed of the second stirring jig 121) is appropriately adjusted between, for example, 200 to 2000 rpm, and rotates at a speed faster than that of the first rotation shaft 112.

At least two stirring blades 123 are attached to the second rotating shaft 122 so as to be aligned in the vertical direction. When distinguishing between the two stirring blades 123, the uppermost stirring blade is referred to as the first stirring blade 123a, and the stirring blade located one below the first stirring blade 123a is referred to as the second stirring blade 123b.

Here, let L (mm) be the length along the vertical direction from the lowermost portion to the uppermost portion 113a of the arm portion 113 of the first stirring jig 111. That is, the length L of the arm portion 113 is from the position Q corresponding to the lowermost portion of the arm portion 113 (equal to the lowermost portion 112a of the first rotation shaft 112 in FIG. 3) to the position P of the uppermost portion 113a. It is the length along the vertical direction. On the other hand, in the configuration of FIG. 4, the arm 113 is curved to a position R further below the lowermost 112a of the first rotation shaft 112, and then extends upward toward the uppermost 113a. The length L of 113 is a length along the vertical direction from the position R to the position P. The length L of the arm portion 113 is preferably 1/4 or more, more preferably 1/3 or more, and 1/2 or more of the length (depth) in the vertical direction of the stirring tank 101. Is even more desirable.

Further, in FIGS. 3 and 4, the position where the arm portion 113 of the first stirring jig 111 is vertically lowered by (1/3) L from the uppermost portion 113a (equal to the position P) is referred to as the position A. do. In the present embodiment, the first stirring blade 123a of the second stirring jig 121 is located above the position A including the above position A, and is made of resin by rotation about the second rotation shaft 122. It is composed of stirring blades that cause the vertical flow of the. As the stirring blade, the paddle type stirring blade shown in FIG. 8 or the propeller type stirring blade shown in FIG. 9 can be used.

Further, the second stirring blade 123b of the second stirring jig 121 is located below the above position A, and is vertically rotated by the first stirring blade 123a due to the rotation about the second rotation shaft 122. It is composed of a stirring blade that causes a flow of the resin drawn downward in a direction perpendicular to the second rotation axis 122. The stirring blade is composed of the turbine type stirring blade shown in FIG. 10 or the disc type (melting type) stirring blade shown in FIG.

In the stirring preparation step, the dope composition is put into the stirring tank 101 of the stirring device 100 having the above configuration. Dope compositions include resins, solvents and additives. Here, as the resin, a pellet-shaped resin such as an acrylic resin, a cycloolefin resin, or a polyarylate resin is used. Further, as the solvent, methylene chloride, chloroform or the like is used. As the additive, fine particles (matting agent), a plasticizer, or the like are used. Since the specific gravity of the pellet-shaped resin is small with respect to the specific gravity of the solvent (that is, the resin is lighter than the solvent), even if a part of the resin is dissolved in the solvent at the beginning of adding the resin to the solvent, it remains. Most of them float on the surface of the solvent.

When the resin and the solvent are stirred by rotating the first stirring jig 111 and the second stirring jig 121, respectively, first, the rotation of the first stirring blade 123a of the second stirring jig 121 causes the mixture in the solvent. In the vertical direction of the resin (vertical direction in FIG. 3), that is, a flow of drawing the resin from above to below occurs. Then, the rotation of the second stirring blade 123b causes the resin drawn vertically downward by the first stirring blade 123a to flow in the direction perpendicular to the second rotation axis 122, that is, the horizontal direction perpendicular to the vertical direction. A flow (in the left-right direction in FIG. 3) occurs. At this time, since the arm 113 of the first stirring jig 111 rotates about the first rotating shaft 112, the resin and the solvent flowing in the horizontal direction by the second stirring blade 123b are sheared in the shearing direction ( It can be agitated in the depth direction in FIG.

The resin and the solvent in the stirring tank 101 are uniformly agitated by the first stirring blade 123a (vertical direction) and the second stirring blade 123b and the arm 113 (horizontal direction, shearing direction). Moreover, it is agitated efficiently and uneven agitation is reduced. As a result, the viscosity of the dope prepared by stirring is stabilized, so that uneven film thickness can be reduced when an optical film is formed using the above-mentioned doping. Further, since the resin can be uniformly stirred in the stirring tank 101, it is difficult for the resin to aggregate in the stirring tank 101 to form agglomerates (undissolved substances) and other dissolution defects are less likely to occur, which is caused by the undissolved substances. It is also possible to reduce the generation of bright spot foreign matter.

Further, if the dope viscosity is unstable, it is necessary to adjust the dope viscosity (film thickness adjustment) in order to reduce the film thickness unevenness, and the productivity of the optical film is lowered by the amount of such adjustment time required. However, in the present embodiment, since the dope viscosity is stabilized by uniform stirring, it is possible to avoid the above-mentioned decrease in the productivity of the optical film.

Further, when the specific gravity of the resin is A, the specific gravity of the solvent is B, and the difference in specific gravity (BA) is Δ, if Δ> 0.1, the resin floats on the liquid surface of the solvent due to the difference in specific gravity. This makes it easier for solvent to be generated. However, in the present embodiment, as described above, the stirring unevenness can be reduced and the inside of the stirring tank 101 can be uniformly stirred. Therefore, even under the condition of Δ> 0.1, the generated splicing powder is reduced by stirring. , The generation of undissolved matter can be suppressed. As a result, in the film-formed optical film, it is possible to reduce the bright spot foreign matter caused by the undissolved substance. If the difference in specific gravity between the solvent and the resin is too large, it is difficult for the resin to flow downward in the solvent even by stirring in the vertical direction, and there is a concern that the effect of reducing stirring unevenness will be reduced. Therefore, it is desirable that Δ is less than 0.5. That is, it can be said that the stirring method of the present embodiment is particularly effective when a resin and a solvent having 0.1 <Δ <0.5 are selected to prepare a dope and an optical film is formed.

Incidentally, the specific gravity of the polymethylcrylate resin (PMMA), which is an acrylic resin, is 1.17, the specific gravity of the cycloolefin resin is 1.01, and the specific gravity of the polyarylate resin is 1.21. .. The specific gravity of methylene chloride is 1.32, and the specific density of chloroform is 1.48. Therefore, since 0.1 <Δ <0.5 is satisfied with any of the above-mentioned resins for any of the above-mentioned resins, the resin and the solvent are stirred by the method of the present embodiment. By producing a dope and forming an optical film, it is possible to reduce the occurrence of film thickness unevenness and bright spot foreign matter due to stirring unevenness. It can be said that the more desirable range of the specific gravity difference Δ is 0.1 <Δ <0.31 from the minimum and maximum values of the specific gravity difference in the combination of each of the above resins and each of the above solvents.

Further, in a configuration using two stirring blades that generate upstream and downstream like a conventional stirring device, the momentum of the resin flowing from the upper side to the lower side becomes strong, and the reaction at the bottom of the stirring tank causes the resin to move from the lower side to the upper side. The resin may adhere to the top surface (lid part) of the stirring tank due to the vigorous flow. In this respect, in the present embodiment, since the stirring blade (first stirring blade 123a) for generating upstream and downstream and the stirring blade (second stirring blade 123b) for generating horizontal flow are used, the vertical direction is vertical. The resin and the solvent can be uniformly stirred in the stirring tank 101 by appropriately suppressing the flow of the resin. Therefore, the resin hardly adheres to the top surface 101b of the stirring tank 101.

Further, in the present embodiment, among the plurality of stirring blades of the second stirring jig 121, the first stirring blade 123a located at the uppermost portion is located above the position A including the position A, and the second stirring blade is located above the position A. Since the stirring blade 123b of No. 1 is located below the position A, the rotation of the first stirring blade 123a causes the second stirring blade 123b to be between the arm portion 113 of the first stirring jig 111. The resin is reliably drawn in, and the drawn resin and the solvent can be reliably agitated in the horizontal direction and the shearing direction by the rotation of the second stirring blade 123b and the rotation of the arm portion 113.

Further, among the plurality of stirring blades of the second stirring jig 121, the first stirring blade 123a located at the uppermost portion is a paddle type or propeller type stirring blade, so that the rotation of the first stirring blade 123a Therefore, it is possible to surely generate a vertical flow in the stirring tank 101, particularly a resin flow from the upper side to the lower side. On the other hand, since the second stirring blade 123b located below the first stirring blade 123a is a turbine type or disk type stirring blade, the rotation of the second stirring blade 123b causes the resin to flow in the horizontal direction. It can be reliably generated.

Further, since the first stirring jig 111 is composed of an anchor type or anchor paddle type stirring blade (bottom blade), a space is formed between the first rotating shaft 112 and the arm portion 113. .. Therefore, as in the present embodiment, the second stirring jig 121 can be positioned in a part of the space. Then, it is possible to realize a configuration in which the resin and the solvent in the stirring tank 101 are uniformly stirred by the rotation of the first stirring jig 111 and the rotation of the second stirring jig 121.

By the way, FIG. 12 is a cross-sectional view showing another configuration of the second stirring jig 121. The second stirring jig 121 may further have a third stirring blade 123c in addition to the first stirring blade 123a and the second stirring blade 123b described above. The third stirring blade 123c is located one below the second stirring blade 123b, and like the second stirring blade 123b, the turbine type stirring blade shown in FIG. 10 or the disc type stirring blade shown in FIG. 11 Consists of.

The second stirring jig 121 has three stirring blades (first stirring blade 123a, second stirring blade 123b, third stirring blade 123c), of which the stirring blades other than the uppermost one (second stirring blade 123c). The stirring blade 123b and the third stirring blade 123c) are turbine type or disk type stirring blades, so that the resin drawn downward by the rotation of the first stirring blade 123a is removed from the second stirring blade 123b. The rotation of the third stirring blade 123c causes the stirring blade 101 to flow horizontally in a wide range in the vertical direction (depth direction), and the resin and the solvent are allowed to flow in the vertical direction by the rotation of the arm portion 113. It can be agitated in the shearing direction in a wide range. That is, the rotation of the third stirring blade 123c causes a horizontal resin flow even at a deeper position in the stirring tank 101, and the rotation of the arm 113 enables stirring in the shearing direction. As a result, uniform stirring in the stirring tank 101 can be efficiently performed in a shorter time.

In the above, the case where the number of the arm portions 113 of the first stirring jig 111 is two has been described, but the number of the arm portions 113 may be one or three or more. .. However, considering the efficiency of stirring, it is desirable that the number of arms 113 is a plurality.

Further, when a plurality of arm portions 113 are provided on the first rotation shaft 112, the plurality of arm portions 113 are equidistantly spaced around the first rotation shaft 112 in a plane perpendicular to the first rotation shaft 112. It is desirable from the viewpoint of further reducing the stirring unevenness in the stirring tank 101. For example, when two arm portions 113 are provided on the first rotation shaft 112 as shown in FIG. 3, it is desirable that each arm portion 113 is arranged around the first rotation shaft 112 at an interval of 180 °. Further, when the three arm portions 113 are provided on the first rotation shaft 112, it is desirable that the arm portions 113 are arranged around the first rotation shaft 112 at 120 ° intervals. Further, when four arm portions 113 are provided on the first rotation shaft 112, it is desirable that each arm portion 113 is arranged around the first rotation shaft 112 at 90 ° intervals.

Further, in the above, the case where the number of the second stirring jigs 121 in the stirring tank 101 is two has been described, but the number of the second stirring jigs 121 may be one. There may be three or more. However, considering the efficiency of stirring, it is desirable that the number of the second stirring jigs 121 is a plurality.

Further, when a plurality of second stirring jigs 121 are provided, the second stirring jig 121 is placed in the stirring tank 101 in a plane perpendicular to the first rotation axis 112 of the first stirring jig 111. It is desirable that a plurality of the first rotating shafts 112 are provided around the first rotating shaft 112 at equal angular intervals from the viewpoint of further reducing the stirring unevenness in the stirring tank 101. For example, when two second stirring jigs 121 are provided in the stirring tank 101 as shown in FIG. 3, each second stirring jig 121 is arranged around the first rotating shaft 112 at 180 ° intervals. Is desirable. Further, when the three second stirring jigs 121 are provided in the stirring tank 101, it is desirable that each of the second stirring jigs 121 is arranged around the first rotating shaft 112 at 120 ° intervals. Further, when four second stirring jigs 121 are provided in the stirring tank 101, it is desirable that each of the second stirring jigs 121 is arranged around the first rotating shaft 112 at 90 ° intervals. The number of the second stirring jig 121 and the number of the arms 113 of the first stirring jig 111 may be the same or different.

〔resin〕
In the present embodiment, any of an acrylic resin, a cycloolefin resin, and a polyarylate resin can be used as the resin used for producing the optical film, that is, the resin that is put into the stirring tank 101 and stirred and mixed with the solvent. ..

<Acrylic resin>
As the (meth) acrylic resin, Tg (glass transition temperature) is preferably 115 ° C. or higher, more preferably 120 ° C. or higher, still more preferably 125 ° C. or higher, and particularly preferably 130 ° C. or higher. When the Tg is 115 ° C. or higher, the durability of the optical film is improved. The upper limit of Tg of the (meth) acrylic resin is not particularly limited, but is preferably 170 ° C. or lower from the viewpoint of moldability.

As the (meth) acrylic resin, any suitable (meth) acrylic resin may be adopted as long as the effects of the present embodiment are not impaired. For example, poly (meth) acrylic acid ester such as polymethyl methacrylate, methyl methacrylate- (meth) acrylic acid copolymer, methyl methacrylate- (meth) acrylic acid ester copolymer, methyl methacrylate-acrylic acid ester-. (Meta) acrylate copolymer, (meth) methyl acrylate-styrene copolymer (MS resin, etc.), polymer having alicyclic hydrocarbon group (for example, methyl methacrylate-cyclohexyl methacrylate copolymer, etc.) (Methyl methacrylate- (meth) acrylate norbornyl copolymer, etc.) can be mentioned. Preferred are C1-6 alkyl poly (meth) acrylates such as methyl poly (meth) acrylate. More preferably, a methyl methacrylate-based resin containing methyl methacrylate as a main component (50 to 100% by mass, preferably 70 to 100% by mass) can be mentioned. As described above, the acrylic resin includes not only the acrylic resin itself but also a copolymer of the acrylic resin and another resin (compound).

Specific examples of the (meth) acrylic resin include Acrypet VH, Acrypet VRL20A, Dianar BR52, BR80, BR83, BR85, BR88 (manufactured by Mitsubishi Rayon Co., Ltd.), and KT75 (manufactured by Electrochemical Industry Co., Ltd.). ), Delpet 60N, 80N (manufactured by Asahi Kasei Chemicals Co., Ltd.), (meth) acrylic resin having a ring structure in the molecule described in JP-A-2004-70296, by intramolecular cross-linking or intramolecular cyclization reaction. Examples thereof include a high Tg (meth) acrylic resin system obtained.

As the (meth) acrylic resin, it is also preferable to use a (meth) acrylic resin having a lactone ring structure. Examples of the (meth) acrylic resin having a lactone ring structure include JP-A-2000-230016, JP-A-2001-151814, JP-A-2002-120326, JP-A-2002-254544, and JP-A-2005- Examples thereof include those described in Japanese Patent Application Laid-Open No. 146084.

Further, as the (meth) acrylic resin, an acrylic resin having a structural unit of an unsaturated carboxylic acid alkyl ester and a structural unit of glutaric anhydride can be used. Examples of the acrylic resin include JP-A-2004-70290, JP-A-2004-70296, JP-A-2004-163924, JP-A-2004-292812, JP-A-2005-314534, JP-A-2006-. The ones described in JP-A-131898, JP-A-2006-206881, JP-A-2006-265532, JP-A-2006-283013, JP-A-2006-299005, JP-A-2006-335902, etc. are listed. Be done.

Further, as the (meth) acrylic resin, a thermoplastic resin having a glutarimide unit, a (meth) acrylic acid ester unit, and an aromatic vinyl unit can be used. Examples of the thermoplastic resin include JP-A-2006-309033, JP-A-2006-317560, JP-A-2006-328329, JP-A-2006-328334, JP-A-2006-337491, and JP-A-2006. Examples thereof include those described in JP-A-376492, JP-A-2006-337493, and JP-A-2006-337569.

<Cycloolefin resin>
Examples of the cycloolefin resin (cycloolefin polymer) include a monomer polymer or a copolymer having a structure represented by the following general formula (S).

In the formula, R ^{1 to} R ⁴ are independently hydrogen atom, hydrocarbon group, halogen atom, hydroxy group, carboxy group, acyloxy group, aryloxycarbonyl group, alkoxycarbonyl group, alkoxy group, cyano group and amide group, respectively. , Idyl group, silyl group, or polar group (ie, halogen atom, hydroxy group, acyloxy group, aryloxycarbonyl group, alkoxycarbonyl group, alkoxy group, cyano group, amide group, imide group, or silyl group) It is a hydrocarbon group.

However, ^{two or more of R 1 to} R ⁴ may be bonded to each other to form an unsaturated bond, a monocyclic ring or a polycyclic ring, and the monocyclic or polycyclic ring has a double bond. Alternatively, an aromatic ring may be formed. An alkylidene group may be formed by ^{R 1} and R ² or by R ³ and R ^4. p and m are integers greater than or equal to 0.

In the above general formula (S), the ^{hydrocarbon group represented by R 1} and R ³ is preferably a hydrocarbon group having 1 to 10 carbon atoms, more preferably 1 to 4, and particularly preferably 1 to 2 hydrocarbon groups.

It is preferable that R ² and R ⁴ are hydrogen atoms or monovalent organic groups, ^{and at least one of R 2} and R ⁴ shows a polar group having a polarity other than a hydrogen atom and a hydrocarbon group, and m is 0. The integer of ~ 3 and p are integers of 0 to 3, more preferably m + p = 0 to 4, still more preferably 0 to 2, particularly preferably m = 1 and p = 0.

The specific monomer having m = 1 and p = 0 is preferable in that the obtained cycloolefin resin has a high glass transition temperature and excellent mechanical strength. The glass transition temperature referred to here is a value obtained by a method based on JIS K 7121-2012 using DSC (Differential Scanning Colorimetry).

Examples of the polar group of the specific monomer include a carboxy group, a hydroxy group, an alkoxycarbonyl group, an allyloxycarbonyl group, an amino group, an amide group and a cyano group, and these polar groups include a linking group such as a methylene group. They may be combined via.

Further, a hydrocarbon group in which a polar divalent organic group such as a carbonyl group, an ether group, a silyl ether group, a thioether group or an imino group is bonded as a linking group is also mentioned as a polar group.

Among these, a carboxy group, a hydroxy group, an alkoxycarbonyl group or an allyloxycarbonyl group is preferable, and an alkoxycarbonyl group or an allyloxycarbonyl group is particularly preferable.

Furthermore, as for the monomer in which at least one of ^{R 2} and R ⁴ _{is a polar group represented by the formula − (CH 2} ) _n COOR, the obtained cycloolefin resin has a high glass transition temperature, low hygroscopicity, and various materials. It is preferable in that it has excellent adhesion to and from.

In the above formula for the specific polar group, R is a hydrocarbon group having 1 to 12 carbon atoms, more preferably 1 to 4, particularly preferably 1 to 2, an alkyl group.

Specific examples of the copolymerizable monomer include cycloolefin resins such as cyclobutene, cyclopentene, cycloheptene, cyclooctene, and dicyclopentadiene.

The number of carbon atoms of the cycloolefin is preferably 4 to 20, and more preferably 5 to 12.

In the present embodiment, the cycloolefin resin may be used alone or in combination of two or more.

The preferred molecular weight of the cycloolefin resin is 0.2 to ⁵ _{cm 3 / g at an intrinsic viscosity [η] inh} , more preferably 0.3 to ³ cm 3 / g, and particularly preferably 0.4 to 1.5 cm ³ / g. The polystyrene-equivalent number average molecular weight (Mn) measured by gel permeation chromatography (GPC) is 8000 to 10000, more preferably 1000 to 80000, and particularly preferably 12000 to 50000, and the weight average molecular weight (Mw). Is 2000 to 300,000, more preferably 30,000 to 250,000, and particularly preferably 40,000 to 200,000.

When the intrinsic viscosity [η] _inh , the number average molecular weight and the weight average molecular weight are within the above ranges, the heat resistance, water resistance, chemical resistance and mechanical properties of the cycloolefin resin and the molding process of the optical film of the present embodiment are obtained. Good sex.

The glass transition temperature (Tg) of the cycloolefin resin is usually 110 ° C. or higher, preferably 110 to 350 ° C., more preferably 120 to 250 ° C., and particularly preferably 120 to 220 ° C. A case where the Tg is 110 ° C. or higher is preferable because deformation is unlikely to occur due to use under high temperature conditions or secondary processing such as coating and printing.

On the other hand, when the Tg is 350 ° C. or lower, it is possible to avoid the case where the molding process becomes difficult and reduce the possibility that the resin is deteriorated by the heat during the molding process.

For the cycloolefin resin, for example, a specific hydrocarbon-based resin described in JP-A-9-221577 and JP-A-10-287732, or a known heat, as long as the effects of the present embodiment are not impaired. Plastic resins, thermoplastic elastomers, rubber polymers, organic fine particles, inorganic fine particles, etc. may be blended, and specific wavelength dispersants, sugar ester compounds, antioxidants, peeling accelerators, rubber particles, plasticizers, ultraviolet rays, etc. may be blended. Additives such as absorbents may be included.

Further, as the cycloolefin resin, a commercially available product can be preferably used. As examples of commercially available products, JSR Corporation sells them under the trade names of ARTON (registered trademark) G, ARTON F, ARTON R, and ARTON RX. Further, it is commercially available from Nippon Zeon Corporation under the trade name of ZEONOR (registered trademark) ZF14, ZF16, ZEONEX (registered trademark) 250 or ZEONEX 280, and these can be used.

<Polyarylate resin>
The polyarylate resin contains at least an aromatic dialcohol component unit and an aromatic dicarboxylic acid component unit.

(Aromatic dialcohol component unit)
The aromatic dialcohol for obtaining the aromatic dialcohol component unit is preferably bisphenols represented by the following formula (1), and more preferably bisphenols represented by the following formula (1').

L in the general formulas (1) and (1') is a divalent organic group. The divalent organic group is preferably a single bond, an alkylene group, -S-, -SO-, -SO _2- , -O-, -CO- or -CR _{1 R 2-} (R ₁ and R ₂ are each other. Combine to form an aliphatic or aromatic ring).

The alkylene group is preferably an alkylene group having 1 to 10 carbon atoms, and examples thereof include a methylene group, an ethylene group, and an isopropylidene group. The alkylene group may further have a substituent such as a halogen atom or an aryl group.

R ₁ and R ₂ of −CR ₁ R ₂ − are bonded to each other to form an aliphatic ring or an aromatic ring, respectively. The aliphatic ring is preferably an aliphatic hydrocarbon ring having 5 to 20 carbon atoms, and preferably a cyclohexane ring which may have a substituent. The aromatic ring is an aromatic hydrocarbon ring having 6 to 20 carbon atoms, and is preferably a fluorene ring which may have a substituent. _{Examples of −CR 1} R ₂₋ forming a cyclohexane ring which may have a substituent include cyclohexane-1,1-diyl group, 3,3,5-trimethylcyclohexane-1,1-diyl group and the like. included. _{Examples of −CR 1} R ₂₋ forming a fluorene ring which may have a substituent include a fluoreneyl group represented by the following formula.

R of the general formulas (1) and (1') can independently be an alkyl group having 1 to 5 carbon atoms or an aryl group having 6 to 10 carbon atoms. n is an independently integer of 0 to 4, preferably an integer of 0 to 3.

Examples of bisphenols in which L is an alkylene group include 1,1-bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, and 1,1-bis (4-methyl-2). -Hydroxyphenyl) methane, 1,1-bis (3,5-dimethyl-4-hydroxyphenyl) methane, 2,2-bis (4-hydroxyphenyl) -4-methylpentane, 2,2-bis (4-) Hydroxyphenyl) propane (BPA), 2,2-bis (3-methyl-4-hydroxyphenyl) propane (BPC), 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) propane (TMBPA), etc. Is included. Among them, 2,2-bis (4-hydroxyphenyl) propane (BPA), 2,2-bis (3-methyl-4-hydroxyphenyl) propane (BPC), 2,2-bis (3,5-dimethyl-). Isopropyridene-containing bisphenols such as 4-hydroxyphenyl) propane (TMBPA) are preferred.

Examples of bisphenols with L of -S-, -SO- or -SO _2- are bis (4-hydroxyphenyl) sulfone, bis (2-hydroxyphenyl) sulfone, bis (3,5-dimethyl-4). -Hydroxyphenyl) sulfone (TMBPS), bis (3,5-diethyl-4-hydroxyphenyl) sulfone, bis (3-methyl-4-hydroxyphenyl) sulfone, bis (3-ethyl-4-hydroxyphenyl) sulfone, Bis (4-hydroxyphenyl) sulfide, bis (3,5-dimethyl-4-hydroxyphenyl) sulfide, bis (3,5-diethyl-4-hydroxyphenyl) sulfide, bis (3-methyl-4-hydroxyphenyl) Includes sulfide, bis (3-ethyl-4-hydroxyphenyl) sulfide, 2,4-dihydroxydiphenyl sulfone and the like. Examples of bisphenols with L -O- include 4,4'-dihydroxydiphenyl ethers. Examples of bisphenols with L -CO- include 4,4'-dihydroxydiphenylketones.

An example of bisphenols in which L is −CR ₁ R ₂ − and R ₁ and R ₂ bind to each other to form an aliphatic ring is 1,1-bis (4-hydroxyphenyl) cyclohexane (BPZ). , And bisphenols having a cyclohexane skeleton such as 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane (BPTMC).

Examples of bisphenols in which L is −CR ₁ R ₂ − and R ₁ and R ₂ are bonded to each other to form an aromatic ring are 9,9-bis (3-methyl-4-hydroxyphenyl). Includes bisphenols having a fluorene skeleton such as fluorene (BCF), 9,9-bis (3,5-dimethyl-4-hydroxyphenyl) fluorene (BXF).

The aromatic dialcohol component constituting the polyarylate may be one kind or two or more kinds.

Among these, from the viewpoint of increasing the solubility of the resin in the solvent and improving the adhesion of the film to the metal, for example, a sulfur atom (-S-, -SO- or -SO _2- ) is added to the main chain. The contained bisphenols are preferable. From the viewpoint of increasing the heat resistance of the film, for example, bisphenols containing a sulfur atom in the main chain and bisphenols having a cycloalkylene skeleton are preferable. From the viewpoint of reducing the birefringence of the film and increasing the wear resistance, bisphenols having a fluorene skeleton are preferable.

Bisphenols having a cyclohexane skeleton and bisphenols having a fluorene skeleton are preferably used in combination with bisphenols containing an isopropylidene group. In that case, the content ratio of the bisphenol having a cyclohexane skeleton or the bisphenol having a fluorene skeleton to the bisphenol containing an isopropylidene group is 10/90 to 90/10 (molar ratio), preferably 20/80 to 20/80. It can be 80/20 (molar ratio).

The polyarylate may further contain an aromatic multihydric alcohol component unit other than the aromatic dialcohol component as long as the effect of the present embodiment is not impaired. Examples of aromatic polyhydric alcohol components include the compounds described in paragraph [0015] of Japanese Patent No. 4551503. Specifically, tris (4-hydroxyphenyl) methane, 4,4'-[1- [4- [1- (4-hydroxyphenyl) -1-methylethyl] phenyl] ethylidene] bisphenol, 2,3. Includes 4,4'-tetrahydroxybenzophenone, 4- [bis (4-hydroxyphenyl) methyl] -2-methoxyphenol, tris (3-methyl-4-hydroxyphenyl) methane and the like. The content ratio of these aromatic polyhydric alcohol component units can be appropriately set according to the required characteristics, and is, for example, 5 with respect to the total of the aromatic dialcohol component units and the other aromatic polyhydric alcohol component units. It can be less than or equal to mol%.

(Aromatic dicarboxylic acid component unit)
The aromatic dicarboxylic acid constituting the aromatic dicarboxylic acid component unit can be terephthalic acid, isophthalic acid or a mixture thereof.

A mixture of terephthalic acid and isophthalic acid is preferable from the viewpoint of enhancing the mechanical properties of the film. The content ratio of terephthalic acid and isophthalic acid is preferably terephthalic acid / isophthalic acid = 90/10 to 10/90 (molar ratio), more preferably 70/30 to 30/70, and even more preferably 50/50. When the content ratio of terephthalic acid is in the above range, a polyarylate having a sufficient degree of polymerization can be easily obtained, and a film having sufficient mechanical properties can be easily obtained.

The polyarylate may further contain aromatic dicarboxylic acid component units other than terephthalic acid and isophthalic acid as long as the effects of the present embodiment are not impaired. Examples of such aromatic dicarboxylic acid components include orthophthalic acid, 2,6-naphthalenedicarboxylic acid, diphenic acid, 4,4'-dicarboxydiphenyl ether, bis (p-carboxyphenyl) alkane, 4,4'-. Dicarboxyphenyl sulfone and the like are included. The content ratio of the aromatic dicarboxylic acid component unit other than terephthalic acid and isophthalic acid can be appropriately set according to the required characteristics, but is the total of the terephthalic acid component, the isophthalic acid component unit and the other aromatic dicarboxylic acid component units. For example, it can be 5 mol% or less.

(Glass-transition temperature)
The glass transition temperature of the polyarylate is preferably 260 ° C. or higher and 350 ° C. or lower, more preferably 265 ° C. or higher and lower than 300 ° C., and further preferably 270 ° C. or higher and lower than 300 ° C.

The glass transition temperature of polyarylate can be measured according to JIS K7121 (1987). Specifically, using a DSC6220 manufactured by Seiko Instruments Inc. as a measuring device, measurement can be performed under the conditions of a polyarylate sample of 10 mg and a heating rate of 20 ° C./min.

The glass transition temperature of polyarylate can be adjusted by the type of aromatic dialcohol component constituting polyarylate and the like. In order to raise the glass transition temperature, for example, it is preferable to include "a unit derived from bisphenols containing a sulfur atom in the main chain" as an aromatic dialcohol component unit.

(Intrinsic viscosity)
The intrinsic viscosity of the polyarylate is preferably 0.3 to 1.0 dl / g, more preferably 0.4 to 0.9 dl / g, still more preferably 0.45 to 0.8 dl / g, and 0. It is more preferably 5 to 0.7 dl / g. When the intrinsic viscosity of polyarylate is 0.3 dl / g or more, the molecular weight of the resin composition tends to be constant or higher, and a film having sufficient mechanical properties and heat resistance can be easily obtained. When the intrinsic viscosity of polyarylate is 1.0 dl / g or less, it is possible to suppress an excessive increase in the viscosity of the solution during film formation.

Intrinsic viscosity can be measured according to ISO 1628-1. Specifically, a solution prepared by dissolving a polyarylate sample in 1,1,2,2-tetrachloroethane so as to have a concentration of 1 g / dl is prepared. The intrinsic viscosity of this solution at 25 ° C. is measured using an Ubbelohde viscous tube.

The method for producing the polyarylate may be a known method, preferably an interface in which an aromatic dicarboxylic acid halide dissolved in an organic solvent incompatible with water and an aromatic dialcohol dissolved in an alkaline aqueous solution are mixed. It may be a polymerization method (WM EARECKSON, J. Poly. Sci. XL399, 1959, Japanese Patent Publication No. 40-1959).

The content of the polyarylate may be 50% by mass or more, preferably 60% by mass or more, and more preferably 80% by mass or more with respect to the entire polyarylate film.

〔solvent〕
In the present embodiment, the solvent used for producing the optical film, that is, the solvent for dissolving the above-mentioned resin in the stirring tank of the stirring device, is, for example, dichloromethane (methylene chloride, methylene chloride), chloroform, ethanol, butanol, isopropanol. , N-Methyl-2-pyrrolidone, 1,3-dimethylimidazolidinone, N, N-dimethylacetamide, N, N-dichloroacetamide, N, N-dimethylformamide, N, N-diethylformamide, N-methylcaprolactam , Hexamethylphosphoramide, Tetrahydrofuran, Dichloromethane, m-cresol, Phenol, p-Chlorphenol, 2-Chlor-4-hydroxytoluene, Diglime, Triglime, Tetrahydrofuran, Dioxane, γ-Butylollactone, 1,3 -Dioxolane, cyclohexanone, cyclopentanone, 1,4-dioxane, epsilon caprolactam, tetrahydrofuran (THF) and the like can be used, and these can be used alone or in admixture of two or more. In addition to these solvents, poor solvents such as hexane, heptane, benzene, toluene, xylene, chlorobenzene, and o-dichlorobenzene may be used.

〔Additive〕
In the production of the optical film of the present embodiment, as additives to be contained in the dope, fine particles, a plasticizer, an ultraviolet absorber, an antioxidant, a sugar ester compound, a phase difference adjuster, a light stabilizer, an antistatic agent, and a release agent. , Thickener and the like may be used. Hereinafter, only the main additives will be described.

<Fine particles (matting agent)>
It is desirable that the optical film of the present embodiment contains a matting agent in order to impart irregularities on the film surface during film formation, ensure slipperiness, and achieve a stable winding shape. By containing the matting agent, it is possible to prevent the produced optical film from being scratched or deteriorated in transportability when being handled.

Examples of the matting agent include fine particles of an inorganic compound and fine particles of a resin. Examples of fine particles of inorganic compounds are silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, silicic acid. Examples thereof include magnesium and calcium phosphate. The fine particles containing silicon are preferable in that the turbidity is low, and silicon dioxide is particularly preferable.

The average particle size of the primary particles of the fine particles is preferably in the range of 5 to 400 nm, more preferably in the range of 10 to 300 nm. These may be mainly contained as secondary aggregates having a particle size in the range of 0.05 to 0.3 μm, and particles having an average particle size in the range of 80 to 400 nm are primary particles without agglomeration. It is also preferable that it is contained as.

The content of these fine particles in the optical film is preferably in the range of 0.01 to 3.0% by mass, and particularly preferably in the range of 0.01 to 2.0% by mass.

The fine particles of silicon dioxide are commercially available under the trade names of Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, and TT600 (manufactured by Nippon Aerosil Co., Ltd.) and can be used. ..

The fine particles of zirconium oxide are commercially available under the trade names of Aerosil R976 and R811 (all manufactured by Nippon Aerosil Co., Ltd.) and can be used.

Examples of the fine particles of the resin include silicone resin, fluororesin, and acrylic resin. A silicone resin is preferable, and a resin having a three-dimensional network structure is particularly preferable. For example, they are commercially available under the trade names of Tospearl 103, 105, 108, 120, 145, 3120 and 240 (all manufactured by Toshiba Silicone Co., Ltd.), and these can be used.

Among these, Aerosil 200V, Aerosil R972V, and Aerosil R812 are particularly preferably used because they have a large effect of lowering the friction coefficient while keeping the haze of the optical film low.

<Plasticizer>
A polyester resin can be used as the plasticizer to be added to the optical film. The polyester resin is obtained by polymerizing a dicarboxylic acid and a diol, and 70% or more of the dicarboxylic acid constituent units (constituent units derived from the dicarboxylic acid) are derived from the aromatic dicarboxylic acid and the diol constituent units (derived from the diol). More than 70% of the constituent units) are derived from aliphatic diols.

The proportion of the structural unit derived from the aromatic dicarboxylic acid is 70% or more, preferably 80% or more, and more preferably 90% or more. The proportion of the constituent units derived from the aliphatic diol is 70% or more, preferably 80% or more, and more preferably 90% or more. Two or more types of polyester resins may be used in combination.

Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, naphthalenedicarboxylic acid such as 2,7-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, and the like. Examples thereof include 3,4'-biphenyldicarboxylic acid and the like and ester-forming derivatives thereof.

As the polyester resin, aliphatic dicarboxylic acids such as adipic acid, azelaic acid and sebacic acid and monocarboxylic acids such as benzoic acid, propionic acid and butyric acid can be used as long as the object of the present invention is not impaired.

Examples of the aliphatic diol include ethylene glycol, 1,3-propylene diol, 1,4-butanediol, 1,4-cyclohexanedimethanol, 1,6-hexanediol and the like, and ester-forming derivatives thereof.

As the polyester resin, monoalcohols such as butyl alcohol, hexyl alcohol and octyl alcohol, and polyhydric alcohols such as trimethylolpropane, glycerin and pentaerythritol can be used as long as the object of the present embodiment is not impaired. ..

A known method such as a direct esterification method or a transesterification method can be applied to the production of the polyester resin. Examples of the polycondensation catalyst used in the production of the polyester resin include known antimony trioxide, antimony pentoxide and other antimony compounds, germanium oxide and other germanium compounds, titanium acetate and other titanium compounds, and aluminum chloride and other aluminum compounds. Yes, but not limited to these.

Preferred polyester resins include polyethylene terephthalate resin, polyethylene terephthalate-isophthalate copolymer resin, polyethylene-1,4-cyclohexanedimethylene-terephthalate copolymer resin, polyethylene-2,6-naphthalenedicarbochelate resin, polyethylene-2, 6-Naphthalenedicarboxylate-terephthalate copolymer resin, polyethylene-terephthalate-4,4'-biphenyldicarboxylate resin, poly-1,3-propylene-terephthalate resin, polybutylene terephthalate resin, polybutylene-2,6-naphthalene There are dicarboxylate resins and the like.

More preferable polyester resins include polyethylene terephthalate resin, polyethylene terephthalate-isophthalate copolymer resin, polyethylene-1,4-cyclohexanedimethylene-terephthalate copolymer resin, polybutylene terephthalate resin and polyethylene-2,6-naphthalenedicarboxylate. Resin is mentioned.

The intrinsic viscosity of the polyester resin (phenol / 1,1,2,2-tetrachloroethane = 60/40 mass ratio measured at 25 ° C. in a mixed solvent) is within the range of ^{0.7 to 2.0 cm 3 / g.} Is preferable, and more preferably, it is in the range of ^{0.8 to 1.5 cm 3 / g.} When the intrinsic viscosity is 0.7 cm ³ / g or more, the molecular weight of the polyester resin is sufficiently high, so that the molded product made of the polyester resin composition obtained by using the intrinsic viscosity has the necessary mechanical properties as the molded product. And the transparency is good. When the intrinsic viscosity is 2.0 cm ³ / g or less, the moldability is good. As the other plasticizer, the compounds described in the general formulas (PEI) and the general formulas (PEII) of paragraphs [0056] to [0080] of JP2013-97279A may be used.

〔Example〕
Specific examples of the present invention will be described below, but the present invention is not limited to these examples.

<Preparation of stirring devices A to I>
First, stirring devices A to I satisfying the conditions shown in Table 1 were prepared. In each of the stirring devices A to I, the width of the stirring tank 101 (diameter of the bottom surface 101a) is 2100 mm, and the height of the liquid level when the resin and the solvent are put into the stirring tank 101 is the first stirring. The height of the uppermost portion 113a of the arm portion 113 from the bottom surface 101a is 2000 mm, and the length L of the arm portion 113 is 1800 mm. The distance between the uppermost portions 113a of the two arm portions 113 (distance in the direction perpendicular to the first rotating shaft 112) is 2050 mm, and the distance between the first rotating shaft 112 and the second rotating shaft 122 is 2050 mm. The distance was 750 mm.

The configurations of the stirring inversions A to I are schematically shown in FIGS. 13 to 18. In these figures, the position of the central portion of the arm portion 113 of the first stirring jig 111 in the height direction is indicated by the position B.

<Manufacturing of optical film 1>
(Synthesis of Acrylic Resin 1 (Copolymer A1))
As a monomer, a mixture of 93.6 parts by mass (90 mol%) of styrene, 7.2 parts by mass (10 mol%) of acrylic acid, 29.4 parts by mass of ethylbenzene, and 3.3 parts by mass of 2-ethylhexanol. 0.04 parts by mass of 2,2-bis (4,5-ditercious butyl peroxide) propane was added to the liquid, and this polymerization liquid was added to a polymerization apparatus having a 5.0 L complete mixing reactor. It was continuously charged at 1.67 L / hour. At this time, the temperature of the fully mixed reactor was adjusted to 135 ° C. Next, the polymer solution continuously discharged from the polymerization reactor is supplied to a bent-type screw extruder whose pressure is reduced to 2.7 to 4.0 kPa to remove volatile components, and the pellet-shaped copolymer A1 is removed. Got The composition ratio of the monomer unit in the copolymer A1 was 90 mol% for the styrene monomer and 10 mol% for the acrylic acid monomer, and the weight average molecular weight was 300,000.

The following components were stirred using the stirring device A prepared above and sufficiently dissolved while heating to prepare Dope 1. At this time, the stirring speed (rotational speed) of the first stirring jig of the stirring device A was 50 rpm, and the stirring speed (rotational speed) of the second stirring jig was 500 rpm. The stirring time in the stirring device A was 5 hours.
(Composition of Dope 1)
Copolymer A1 (Styrene: 90 mol%, Acrylic acid: 10 mol%, Weight average molecular weight: 300,000)
100 parts by mass matting agent R812 (manufactured by Nippon Aerosil Co., Ltd., silica particles, average particle size 8 nm)
0.30 parts by mass Methylene chloride 150 parts by mass Ethanol 5 parts by mass

The prepared dope 1 was uniformly cast on a stainless band support at a temperature of 22 ° C. and a width of 2 m using a belt casting device. With the stainless band support, the solvent was evaporated until the residual solvent amount became 50%, and the obtained film-like material was peeled from the stainless band support at a peeling tension of 162 N / m.

Next, the peeled film-like material was evaporated at 35 ° C., stretched 1.25 times in the width direction (TD direction) by tenter stretching, and dried at a drying temperature of 135 ° C. The amount of residual solvent when stretching by zone stretching was started was 20.0%, and the amount of residual solvent when stretching by tenter was started was 8.0%.

After stretching with a tenter, a relaxation treatment was performed at 130 ° C. for 5 minutes, and then drying was completed while transporting the drying zones at 120 ° C. and 140 ° C. with a large number of rollers. The obtained film was slit to a width of 1.5 m, both ends of the film were knurled with a width of 10 mm and a height of 5 μm, and then wound around a core to prepare an optical film 1 as an acrylic film. The produced optical film 1 had a film thickness of 40 μm and a winding length of 4000 m.

<Manufacturing of optical films 2 to 6>
The optical films 2 to 6 were produced in the same manner as in the production of the optical film 1 except that the resins and the like were stirred using the stirring devices B to F instead of the stirring device A to prepare the dope.

<Manufacturing of optical film 7>
(Synthesis of cycloolefin resin COP1)
As the cycloolefin resin, the cycloolefin resin COP1 synthesized as follows was prepared.

First, 50 g of 8-methoxycarbonyl-8-methyltetracyclo [4.4.0.12, 5.17, 10] -3-dodecene represented by the above structural formula, 1-hexene as a molecular weight regulator 2. 3 g and 100 g of toluene were placed in a nitrogen-substituted reaction vessel and heated to 80 ° C. To this, 0.09 ml of a toluene solution of triethylaluminum (0.6 mol / L) and _{0.29 ml of a toluene solution of methanol-modified WCl 6} (0.025 mol / L) were added, and the mixture was reacted at 80 ° C. for 3 hours to make it heavy. Obtained coalescence. Then, the obtained ring-opening copolymer solution was placed in an autoclave, and 100 g of toluene was further added. Add 2500 ppm of the hydrogenated catalyst RuHCl (CO) [P (C ₆ H ₅ )] ₃ to the amount of monomer charged, set the hydrogen gas pressure to 9 to 10 MPa, and react at 160 to 165 ° C for 3 hours. went. After completion of the reaction, a hydrogenated product was obtained by precipitating in a large amount of methanol solution. The resulting cycloolefin resin COP1 is a hydrogenated product of a ring-opened polymer had a glass transition temperature (Tg) = 167 ℃, weight average molecular weight ^{(Mw) = 13.5 × 10 4} , a molecular weight distribution (Mw / Mn) = 3.06.

(Preparation of fine particle dispersion)
12 parts by mass of fine particles (Aerosil R972V, manufactured by Nippon Aerosil Co., Ltd.) and 88 parts by mass of ethanol were stirred and mixed with a dissolver for 50 minutes and then dispersed with Manton Golly to prepare a fine particle dispersion.

Next, 100 parts by mass of the fine particle dispersion was slowly added to dichloromethane (100 parts by mass) being stirred in the stirring device A. Further, the particles were dispersed by an attritor so that the particle size of the secondary particles became a predetermined size. This was filtered through Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle additive solution.

(Preparation of main doping)
A main dope having the following composition was prepared. First, dichloromethane and ethanol were added to the stirrer A. The cycloolefin resin COP1 and the fine particle additive were added to the stirring device A containing dichloromethane while stirring. This is heated and the resin is melted while stirring, and this is Azumi Filter Paper No. 1 manufactured by Azumi Filter Paper Co., Ltd. The main dope was prepared by filtering using 244. The stirring conditions in the stirring device A are the same as in the production of the optical film 1.
<Composition of main doping>
Cycloolefin resin COP1 100 parts by mass Methylene chloride 200 parts by mass Ethanol 10 parts by mass Fine particle addition liquid 10 parts by mass

(Film formation of optical film)
The prepared dope 1 was uniformly cast on a stainless band support at a temperature of 22 ° C. and a width of 2 m using a belt casting device. With the stainless band support, the solvent was evaporated until the residual solvent amount became 30%, and the obtained film-like material was peeled from the stainless band support at a peeling tension of 162 N / m.

Next, the peeled film-like material was evaporated at 35 ° C., stretched 1.25 times in the width direction (TD direction) by tenter stretching, and dried at a drying temperature of 160 ° C. The amount of residual solvent when stretching by zone stretching was started was 10.0%, and the amount of residual solvent when stretching by tenter was started was 5.0%.

After stretching with a tenter, a relaxation treatment was performed at 160 ° C. for 5 minutes, and then drying was completed while transporting the drying zone at 120 ° C. with a large number of rollers. The obtained film was slit to a width of 1.5 m, both ends of the film were knurled with a width of 10 mm and a height of 5 μm, and then wound around a core to prepare an optical film 7 as a cycloolefin. The produced optical film 7 had a film thickness of 40 μm and a winding length of 4000 m.

<Preparation of optical film 8>
The optical film 8 was produced in the same manner as the optical film 1 except that the solvent used was agitated using chloroform in the same amount as methylene chloride instead of methylene chloride to prepare a dope.

<Manufacturing of optical film 9>
The optical film 9 was produced in the same manner as the optical film 1 except that the dope 2 having the following composition containing the acrylic resin 2 was used instead of the dope 1.
(Composition of Dope 2)
Acrylic resin 2 (Dianar BR85, manufactured by Mitsubishi Rayon Co., Ltd.)
100 parts by mass matting agent R812 (manufactured by Nippon Aerosil Co., Ltd., silica particles, average particle size 8 nm)
0.30 parts by mass Methylene chloride 150 parts by mass Ethanol 5 parts by mass

<Manufacturing of optical film 10>
(Making polyarylate)
After adding 2514 parts by weight of water to the reaction vessel, 22.7 parts by weight of sodium hydroxide and 9,9-bis (3,5-dimethyl-4-hydroxyphenyl) fluorene (BCF) as an aromatic dialcohol component. 35.6 parts by weight, 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) propane (TMBPA) 18.5 parts by weight, p-tert-butylphenol (PTBP) 0.049 parts by weight as a molecular weight modifier Was dissolved, 0.34 parts by weight of a polymerization catalyst (tributylbenzylammonium chloride) was added, and the mixture was stirred.

On the other hand, 26.8 parts by weight of an equal amount mixture of terephthalic acid chloride and isophthalic acid chloride as an aromatic dicarboxylic acid component was weighed and dissolved in 945 parts by weight of methylene chloride. This methylene chloride solution was added to the alkaline aqueous solution prepared above under stirring to initiate polymerization. The polymerization reaction temperature was adjusted to be 15 ° C. or higher and 20 ° C. or lower. The polymerization was carried out for 2 hours, and then acetic acid was added into the system to stop the polymerization reaction, and the organic phase and the aqueous phase were separated.

The operation of separating the obtained organic phase into an organic phase and an aqueous phase was repeated after washing with twice the amount of ion-exchanged water as the organic phase in each washing. The washing was completed when the electrical conductivity of the washing water became less than 50 μS / cm. The washed organic phase was put into a warm water tank equipped with a homomixer at 50 ° C. to evaporate methylene chloride to obtain a powdery polymer. Further dehydration and drying were performed to obtain polyarylate.

14 parts by mass of the polyarylate prepared above and 100 parts by mass of methylene chloride were placed in the stirring device A, and the temperature was gradually raised to 45 ° C. while stirring to completely dissolve the polyarylate. The obtained solution was used as Azumi Filter Paper No. 1 manufactured by Azumi Filter Paper Co., Ltd. Filtration was obtained using 244 to obtain a polymer solution.

The obtained polymer solution was uniformly cast on the stainless steel belt of the belt casting device. A stainless steel belt having a length of 20 m was used. The surface temperature of the stainless steel belt is 35 ° C., and the casting film is blown with air at 35 ° C. to evaporate the solvent until the residual solvent amount reaches 38%, and then the film is peeled off from the stainless steel belt to obtain a film. rice field.

The obtained film-like material was stretched 1.2 times at 170 ° C. in the MD direction by utilizing the difference in peripheral speed between the rolls, and then stretched 1.2 times at 230 ° C. in the TD direction with a tenter.

The stretched film is dried for 30 minutes while being conveyed in a drying device at 125 ° C. by a large number of rolls, and then the film is subjected to nerling processing having a width of 15 mm and a height of 10 μm at both ends in the width direction to obtain a polyarylate film. An optical film 10 having a thickness of 40 μm was obtained.

<Manufacturing of optical films 11 to 13>
The optical films 11 to 13 were produced in the same manner as in the production of the optical film 1 except that the resin and the like were stirred using the stirring devices GI instead of the stirring device A to prepare the dope.

<Preparation of optical film 14>
The optical film 14 was produced in the same manner as in the production of the optical film 1 except that the solvent used was agitated using THF (tetrahydrofuran) in the same amount as methylene chloride instead of methylene chloride to prepare a dope.

<Evaluation>
(Evaluation of film thickness unevenness)
For each of the optical films 1 to 14 produced above, the film thickness (μm) was measured at intervals of 10 mm in the width direction of the film using a micrometer, and the difference between the maximum value and the minimum value of each film thickness ( μm) was defined as uneven film thickness. If the film thickness unevenness is 1.0 μm or less, there is no problem in actual use, and if it exceeds 1.0 μm, there is a problem in actual use.

(Evaluation of bright spot foreign matter)
A sample (produced optical film) is placed between two polarizing plates arranged in an orthogonal state (cross Nicol), light is applied from the outside of one polarizing plate, and the outside of the other polarizing plate is exposed to a transmission microscope. Observed at a magnification of 50 times, the number of foreign substances (bright spot foreign substances) that appeared to shine in an area of ^{25 cm 2} was counted and converted into the number per ^{1 cm 2.} Then, the above observation was performed at 10 places per sample, the number of foreign substances was measured, and the average value was taken as the final number of foreign substances. Then, the foreign matter was evaluated based on the following evaluation criteria.
"Evaluation criteria"
⊚: The number of foreign substances is 0.15 or less per ^{1 cm 2.}
◯: The number of foreign substances is larger than 0.15 per ^{1 cm 2 and 0.20 or less.}
Δ: The number of foreign substances ^{is larger than 0.20 per cm 2} and is 0.25 or less.
X: The number of foreign substances ^{is larger than 0.25 and 0.35 or less per 1 cm 2} , but there is a problem in actual use.
XX: The number of foreign substances ^{is larger than 0.35 per 1 cm 2} , and there is a considerable problem in actual use.

Table 2 shows the resin, solvent, and agitator used for forming the respective optical films 1 to 14, and the results of each evaluation.

From Table 2, in the optical film 11, the film thickness unevenness and the evaluation of foreign matter are poor. This is because the dope used for forming the optical film 11 was prepared by using the stirring device G, but in the stirring device G, as shown in FIG. 17, the second stirring jig 121 Since the first stirring blade 123a at the uppermost portion is located at a position lower than the position A vertically lowered by (1/3) L from the uppermost portion 113a of the arm portion 113 of the first stirring jig 111. It is considered that the resin having a small specific gravity and floating above the solvent could not be efficiently drawn downward by the first stirring blade 123a, resulting in uneven stirring.

Further, also in the optical film 12, the film thickness unevenness and the evaluation of foreign matter are poor. This is because the dope used for the film formation of the optical film 12 was prepared by using the stirring device H, but in the stirring device H, as shown in Table 1, the second stirring jig 121 is the most. Since the upper first stirring blade 123a is composed of a disc-shaped stirring blade that creates a flow in a direction perpendicular to the second rotation axis 122, the resin having a small specific gravity and floating above the solvent is also present. It is probable that the first stirring blade 123a could not efficiently pull the sword downward, resulting in uneven stirring.

Further, also in the optical film 13, the film thickness unevenness and the evaluation of foreign matter are poor. This is because the dope used for forming the optical film 13 was prepared by using the stirring device I, but in the stirring device I, as shown in FIG. 18, the second stirring jig 121 The stirring blade is composed of only the first stirring blade 123a, and the resin drawn downward by the first stirring blade 123a cannot be stirred with the arm 113 in the shearing direction, and as a result, the stirring blade cannot be stirred in the shearing direction. It is probable that the stirring unevenness was large.

Further, even in the optical film 14, the film thickness unevenness and the evaluation of foreign matter are poor. It is considered that this is because the resin used in the film formation of the optical film 13 has a higher specific gravity than the solvent and is heavier, so that the resin does not flow upward even when stirred in the stirring tank 101, and as a result, stirring unevenness occurs. Be done.

On the other hand, in the optical films 1 to 10, the evaluation of the film thickness unevenness and the foreign matter is good. This is because the dope used in the film formation of the optical films 1 to 10 was prepared by using any of the stirring devices A to F. In these stirring devices, (1) the second stirring cure The first stirring blade 123a of the tool 121 is located above the position A and is composed of stirring blades (propeller type, paddle type) that cause a vertical flow of the resin. (2) The second stirring blade 123b is composed of a stirring blade (disk type, turbine type) located below the position B and causing a flow in a direction perpendicular to the second rotation axis 122. This is considered to be because uniform stirring is possible in the stirring tank 101. That is, according to the above (1) and (2), the first stirring blade 123a performs vertical stirring and the second stirring blade 123b and the arm 113 perform shearing in the shearing direction. Even if the specific gravity difference Δ is 0.1 <Δ <0.5, it is considered that the resin and the solvent in the stirring tank 101 are uniformly and efficiently stirred, and the stirring unevenness is reduced.

In particular, in the stirring device F, the second stirring jig 121 has three stirring blades, and the stirring is performed more efficiently. Therefore, the film thickness unevenness and the evaluation of foreign matter are further improved by further reducing the stirring unevenness. It is considered that it has become.

<Preparation of stirring devices J to L>
Next, stirring devices J to L satisfying the conditions shown in Table 3 were prepared. The stirring device J has the same configuration as the stirring device A except that the number of arms of the first stirring jig of the stirring device A is changed from two to one. The stirring device K has the same configuration as the stirring device A except that the number of arms of the first stirring jig of the stirring device A is changed from two to three. At this time, it is assumed that the three arms are provided around the first rotation axis at equal intervals of 120 degrees. The stirring device L has the same configuration as the stirring device A except that the number of arms of the first stirring jig of the stirring device A is changed from two to four. At this time, it is assumed that the four arms are provided around the first rotation axis at equal intervals of 90 degrees.

<Preparation of optical films 15 to 17>
The optical films 15 to 17 were produced in the same manner as in the production of the optical film 1 except that the resin and the like were stirred using the stirring devices J to L instead of the stirring device A to prepare the dope.

<Preparation of stirring devices M to O>
Next, stirring devices M to O satisfying the conditions shown in Table 4 were prepared. The stirring device M has the same configuration as the stirring device A except that the number of the second stirring jigs of the stirring device A is changed from two to one. The stirring device N has the same configuration as the stirring device A except that the number of the second stirring jigs of the stirring device A is changed from two to three. At this time, it is assumed that the three second stirring jigs are provided around the second rotation axis at equal intervals of 120 degrees. The stirring device O has the same configuration as the stirring device A except that the number of the second stirring jigs of the stirring device A is changed from two to four. At this time, it is assumed that the four second stirring jigs are provided around the second rotation axis at equal intervals of 90 degrees.

<Manufacturing of optical films 18 to 20>
The optical films 18 to 20 were produced in the same manner as in the production of the optical film 1 except that the resin and the like were stirred using the stirring devices MO instead of the stirring device A to prepare the dope.

The optical films 15 to 20 produced above were evaluated for film thickness unevenness and foreign matter in the same manner as for the optical film 1 and the like. The results of the evaluation are shown in Table 5.

The stirring device J used for forming the optical film 15 has a smaller number of arms than the stirring device A. Further, the stirring device M used for forming the optical film 18 has a smaller number of second stirring jigs than the stirring device A. However, these stirrers J and M still satisfy the above conditions (1) and (2). Therefore, the optical films 15 and 18 have lower evaluations of film thickness unevenness and foreign matter than the optical film 1, but they are at a level that does not cause any problem in actual use, and the stirring devices J and M also reduce the stirring unevenness. It can be said that the effect has been obtained.

Further, since the stirring devices K and L used in the film formation of the optical films 16 to 17 have a larger number of arms than the stirring device A, the stirring efficiency is further improved as compared with the stirring device A, and the stirring unevenness is caused. It is considered that the reduction was further improved and the evaluation of uneven film thickness and foreign matter was further improved.

Further, since the stirring devices N and O used in the film formation of the optical films 19 to 20 have a larger number of second stirring jigs than the stirring device A, the stirring efficiency is further improved as compared with the stirring device A. It is considered that the uneven stirring was further reduced, and the uneven film thickness and the evaluation of foreign matter were further improved.

〔supplement〕
Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to this, and various modifications can be made without departing from the gist of the invention.

The method for producing the optical film of the present embodiment described above can be expressed as follows.

1. 1. A method for producing an optical film by a solution casting film forming method.
A stirring preparation step of preparing a dope by stirring at least the resin and the solvent in a stirring tank, and
Including a casting step of casting the dope prepared in the stirring preparation step on the support.
The resin is any one of an acrylic resin, a cycloolefin resin, and a polyarylate resin.
When the specific gravity of the resin is A, the specific gravity of the solvent is B, and the specific gravity difference (BA) is Δ,
0.1 <Δ <0.5
And
The stirring tank is provided with a first stirring jig and a second stirring jig.
The first stirring jig is formed in the stirring tank from a first rotating shaft located on a vertical axis passing through the center of the bottom surface of the stirring tank and a lowermost portion of the first rotating shaft. It has an arm portion that is located above the lowermost portion and extends to a position separated from the first rotation axis in the direction of the radius of gyration.
The second stirring jig is aligned with the second rotating shaft extending in the vertical direction so as to pass through the space between the first rotating shaft and the arm portion. It has at least two stirring blades attached to two rotating shafts and has
Let L be the length of the arm of the first stirring jig along the vertical direction, and of the at least two stirring blades of the second stirring jig, the uppermost stirring blade and one below the stirring blade. When the stirring blades located in are the first stirring blade and the second stirring blade, respectively,
The first stirring blade is located above the first stirring jig, including a position vertically lowered by (1/3) L from the uppermost portion of the arm portion of the first stirring jig, and is located above the second stirring blade. It is composed of a stirring blade that causes the vertical flow of the resin by rotation around the rotation axis of the above.
The second stirring blade is located below the position where the first stirring jig is vertically lowered by (1/3) L from the uppermost portion of the arm portion of the first stirring jig, and the second rotation axis is formed. The optical feature is that the resin is drawn vertically downward by the first stirring blade due to the rotation around the center, and is composed of a stirring blade that causes a flow in a direction perpendicular to the second rotation axis. How to make a film.

2. 0.1 <Δ <0.31
The method for producing an optical film according to 1 above.

3. 3. The method for producing an optical film according to 1 or 2, wherein the solvent contains methylene chloride or chloroform.

4. The method for producing an optical film according to any one of 1 to 3, wherein the first stirring blade is a paddle type or propeller type stirring blade.

5. The method for producing an optical film according to any one of 1 to 4, wherein the second stirring blade is a turbine type or disc type stirring blade.

6. The method for producing an optical film according to any one of 1 to 5, wherein the first stirring jig is composed of an anchor type or anchor paddle type stirring blade.

7. The second stirring jig further has a third stirring blade located one below the second stirring blade.
The method for producing an optical film according to any one of 1 to 6, wherein the third stirring blade is a turbine type or disc type stirring blade.

8. The first stirring jig is characterized in that a plurality of the arms are provided around the first rotation axis at equal angle intervals in a plane perpendicular to the first rotation axis. The method for producing an optical film according to any one of 1 to 7.

9. A plurality of the second stirring jigs are provided in the stirring tank, in a plane perpendicular to the first rotation axis of the first stirring jig, and around the first rotation axis at equal angular intervals. The method for producing an optical film according to any one of 1 to 8 above.

10. The method for producing an optical film according to 8 or 9, wherein the equiangular spacing is 180 °.

The present invention can be used for producing an optical film by a solution casting film forming method.

101 Stirring tank 101a Garden surface 111 First stirring jig 112 First rotating shaft 112a Bottom 113 Arm 113a Top 121 Second stirring jig 122 Second rotating shaft 123 Stirring blade 123a First stirring blade 123b 2nd stirring blade 123c 3rd stirring blade A position F Optical film S1 Stirring preparation step S2 Casting step

Claims (10)

A method for producing an optical film by a solution casting film forming method.
A stirring preparation step of preparing a dope by stirring at least the resin and the solvent in a stirring tank, and
Including a casting step of casting the dope prepared in the stirring preparation step on the support.
The resin is any one of an acrylic resin, a cycloolefin resin, and a polyarylate resin.
When the specific gravity of the resin is A, the specific gravity of the solvent is B, and the specific gravity difference (BA) is Δ,
0.1 <Δ <0.5
And
The stirring tank is provided with a first stirring jig and a second stirring jig.
The first stirring jig is formed in the stirring tank from a first rotating shaft located on a vertical axis passing through the center of the bottom surface of the stirring tank and a lowermost portion of the first rotating shaft. It has an arm portion that is located above the lowermost portion and extends to a position separated from the first rotation axis in the direction of the radius of gyration.
The second stirring jig is aligned with the second rotating shaft extending in the vertical direction so as to pass through the space between the first rotating shaft and the arm portion. Has at least two stirring blades attached to the rotating shaft of
Let L be the length of the arm of the first stirring jig along the vertical direction, and of the at least two stirring blades of the second stirring jig, the uppermost stirring blade and one below the stirring blade. When the stirring blades located in are the first stirring blade and the second stirring blade, respectively,
The first stirring blade is located above the first stirring jig, including a position vertically lowered by (1/3) L from the uppermost portion of the arm portion of the first stirring jig, and is located above the second stirring blade. It is composed of a stirring blade that causes the vertical flow of the resin by rotation around the rotation axis of the above.
The second stirring blade is located below the position where the first stirring jig is vertically lowered by (1/3) L from the uppermost portion of the arm portion of the first stirring jig, and the second rotation axis is formed. The optical feature is that the resin is drawn vertically downward by the first stirring blade due to the rotation around the center, and is composed of a stirring blade that causes a flow in a direction perpendicular to the second rotation axis. How to make a film. 0.1 <Δ <0.31
The method for producing an optical film according to claim 1, wherein the optical film is produced. The method for producing an optical film according to claim 1 or 2, wherein the solvent contains methylene chloride or chloroform. The method for producing an optical film according to any one of claims 1 to 3, wherein the first stirring blade is a paddle type or propeller type stirring blade. The method for producing an optical film according to any one of claims 1 to 4, wherein the second stirring blade is a turbine type or disc type stirring blade. The method for producing an optical film according to any one of claims 1 to 5, wherein the first stirring jig is composed of an anchor type or anchor paddle type stirring blade. The second stirring jig further has a third stirring blade located one below the second stirring blade.
The method for producing an optical film according to any one of claims 1 to 6, wherein the third stirring blade is a turbine type or disc type stirring blade. The first stirring jig is characterized in that a plurality of the arms are provided around the first rotation axis at equal angle intervals in a plane perpendicular to the first rotation axis. Item 8. The method for producing an optical film according to any one of Items 1 to 7. A plurality of the second stirring jigs are provided in the stirring tank, in a plane perpendicular to the first rotation axis of the first stirring jig, and around the first rotation axis at equal angular intervals. The method for producing an optical film according to any one of claims 1 to 8, wherein the optical film is produced. The method for producing an optical film according to claim 8 or 9, wherein the equiangular spacing is 180 °.

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