WO2018029955A1

WO2018029955A1 - Method for manufacturing optical film

Info

Publication number: WO2018029955A1
Application number: PCT/JP2017/020867
Authority: WO
Inventors: 西村　浩; 崇南條
Original assignee: コニカミノルタ株式会社
Priority date: 2016-08-10
Filing date: 2017-06-05
Publication date: 2018-02-15
Also published as: KR20180122659A; KR102136476B1; CN109641374A; JPWO2018029955A1; CN109641374B; JP6911863B2

Abstract

A method for manufacturing an optical film comprises an agitation preparation step and a flow expanding step. When a specific gravity of agitated resin is expressed as A, a specific gravity of a solvent is expressed as B, and a gravity difference (B - A) is expressed as ∆, 0.1 < ∆ < 0.5 is satisfied. A first agitation jig (111) has a first rotation shaft (112) and an arm part (113). A second agitation jig (121) has a second rotation shaft (122), a first agitation blade (123a), and a second agitation blade (123b). When a length of the arm part (113) in a vertical direction is expressed as L, the first agitation blade (123a) is placed in a position including or above a position A which is lower than a top part (113a) of the arm part (113) by (1/3) L in the vertical direction. The second agitation blade (123b) is placed below the position A.

Description

Manufacturing method of optical film

The present invention relates to an optical film manufacturing method in which an optical film is formed by a solution-flow casting method, and more particularly to stirring of a dope cast on a support.

Conventionally, as a stirring device for stirring a solution, for example, there is one disclosed in Patent Document 1. In this stirrer, the first flat plate blade member and the second flat plate blade member are arranged side by side along the rotation axis direction on the rotation 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 rotary shaft at an inclination angle that raises the solution based on the rotation of the rotary shaft. By rotating the first flat plate blade member and the second flat plate blade member about the rotation axis, the circulation flow of the solution is generated without being divided in the vertical direction of the stirring tank, and the vertical circulation of the solution is efficiently performed. Mixing can be performed.

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

However, the stirring device of Patent Document 1 is applied to the stirring of the resin and the solvent when preparing the dope used in the solution casting film forming method, and an optical film is formed using the dope prepared by stirring. However, it has been confirmed that film thickness unevenness and bright spot foreign matter are generated in the optical film. About these causes, this inventor estimates as follows.

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

In particular, when a pellet-like resin (for example, an acrylic resin) having a low specific gravity is dissolved in a solvent having a high specific gravity (for example, methylene chloride), the resin tends to float on the liquid surface, and spatter is generated. As a result of the spatter remaining as an undissolved product due to uneven stirring, bright spot foreign matter tends to be generated in the formed optical film.

The present invention has been made to solve the above-mentioned problems, and its purpose is to reduce the unevenness of stirring in the stirring tank, and thereby the film thickness unevenness of the optical film formed and the bright spot foreign matter. It is providing the manufacturing method of the optical film which can reduce generation | occurrence | production of this.

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 method,
A stirring preparation step of preparing a dope by stirring at least a resin and a solvent in a stirring tank;
A casting step of casting the dope prepared in the stirring preparation step on a 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 includes 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, and the first stirring jig is moved in the stirring tank. An arm portion extending from the first rotation axis to a position away from the first rotation axis in a rotational radius direction above the lowermost portion;
The second agitating jig is arranged such that the second agitation jig is aligned along the vertical direction with the second rotation axis extending in the vertical direction so as to pass through the space between the first rotation axis and the arm portion. Having at least two stirring blades attached to two rotating shafts,
The length along the vertical direction of the arm portion of the first stirring jig is L, and among the at least two stirring blades of the second stirring jig, the uppermost stirring blade and one lower side thereof When the stirring blades located at 1 are respectively the first stirring blade and the second stirring blade,
The first stirring blade is located above and including a position vertically lowered by (1/3) L from the uppermost portion of the arm portion of the first stirring jig, and the second stirring blade It is composed of a stirring blade that causes a vertical flow of the resin by rotation about the rotation axis of
The second agitating blade is located below a position vertically lowered by (1/3) L from the uppermost part of the arm portion of the first agitating jig, and the second rotating shaft is It is composed of an agitating blade that causes the resin drawn vertically downward by the first agitating blade to flow in a direction perpendicular to the second rotation axis by rotation around the center.

According to the above manufacturing method, the unevenness of stirring in the stirring tank can be reduced, and thereby the film thickness unevenness of the optical film to be formed and the generation of bright spot foreign matter can be reduced.

It is explanatory drawing which shows the structure of the outline of the manufacturing apparatus of the optical film 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 a 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 other structure of the said 1st stirring jig. It is a perspective view which shows other structure of the said 1st stirring jig. It is a perspective view which shows other structure of the said 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 said stirring apparatus 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 said 2nd stirring jig. It is a perspective view which shows the other structural example of the said 2nd stirring blade. It is sectional drawing which shows the other structure of the said 2nd stirring jig. It is sectional drawing which shows the structural example of the stirring apparatus used in the Example. It is sectional drawing which shows the other structural example of the said stirring apparatus. It is sectional drawing which shows the further another structural example of the said stirring apparatus. It is sectional drawing which shows the further another structural example of the said stirring apparatus. It is sectional drawing which shows the further another structural example of the said stirring apparatus. It is sectional drawing which shows the further another structural example of the said stirring apparatus.

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 value range includes the values of the lower limit A and the upper limit B.

[Method for producing optical film]
FIG. 1 is an explanatory diagram illustrating a schematic configuration of an optical film manufacturing apparatus 1 according to the present embodiment. Moreover, FIG. 2 is a flowchart which shows the flow of the manufacturing process of an optical film. The manufacturing method of the optical film of this embodiment is a method of manufacturing an optical film by a solution casting film forming method. 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 process is demonstrated, referring FIG. 1 and FIG.

<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.

<Casting process>
In the casting step, the dope prepared in the stirring preparation step is fed to the casting die 2 by a conduit through a pressurized metering gear pump or the like, and transferred onto the support 3 made of a rotationally driven stainless steel endless belt for infinite transfer. 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) positioned therebetween. One or both of the rolls 3a and 3b are provided with a driving device (not shown) for applying tension to the support 3 so that 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 until the web 5 can be peeled from the support 3 by the peeling roll 4. Let In order to evaporate the solvent, there are a method of blowing air from the web side, a method of transferring heat from the back surface of the support 3 by a liquid, a method of transferring heat from the front and back by radiant heat, and the like. That's fine.

<Peeling process>
In the above casting process, after drying and solidifying or cooling and solidifying until the web 5 has a peelable film strength on the support 3, the web 5 is peeled with self-supporting property in the peeling process. Peel off by roll 4.

The residual solvent amount 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 lines due to the peeling tension are likely to occur. Therefore, the residual at the time of peeling due to the balance between economic speed and quality. The amount of solvent is determined. The residual solvent amount is defined by the following formula.

Residual solvent amount (% by mass) = (mass before web heat treatment−mass after web heat treatment) / (mass after web heat treatment) × 100
Here, the heat treatment for measuring the residual solvent amount represents performing heat treatment at 115 ° C. for 1 hour.

<Extension 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 lateral 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 a clip or the like and stretched is preferable in order to improve the flatness and dimensional stability of the film. In addition, in the tenter 6, you may dry in addition to extending | stretching. In the stretching step, by stretching the web 5 in both the MD direction and the TD direction, the web 5 can also be stretched (obliquely stretched) in a direction that obliquely intersects the MD direction and the TD direction.

(Drying process)
The web 5 stretched by the tenter 6 is dried by a drying device 7. In the drying device 7, the web 5 is transported by a plurality of transport rolls arranged in a staggered manner as viewed from the side, and the web 5 is dried in the meantime. There is no restriction | limiting in particular in the drying method in the drying apparatus 7, Generally the web 5 is dried using a hot air, infrared rays, a heating roll, a microwave. From the viewpoint of simplicity, a method of drying the web 5 with hot air is preferable.

The web 5 is transported toward the winding device 10 as the optical film F after being dried by the drying device 7.

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

After the cutting step, embossing (knurling) is performed by the embossing part 9 at both ends in the width direction of the optical film F. Embossing 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 at both ends. By such embossing, winding deviation and blocking (attachment between films) in the next winding process can be suppressed as much as possible.

(Winding process)
Finally, the optical film F that has been embossed is wound up by the winding device 10 to obtain the original roll (film roll) of the optical film F. That is, in the winding process, the film roll is manufactured by winding the optical film F around the core while transporting the optical film F. The winding method of the optical film F may be a commonly used winder, and there are methods for controlling tension such as a constant torque method, a constant tension method, a taper tension method, a program tension control method with a constant internal stress, and the like. 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 desirably 1000 to 3200 mm, and the film thickness is desirably 10 to 60 μm.

[About the stirring device]
Next, the stirring apparatus 100 used in the stirring preparation process mentioned above is demonstrated. FIG. 3 is a cross-sectional view schematically showing an example of the stirring device 100. A 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 “lower” and the top surface 101b side is “upper”. A direction in which the bottom surface 101a and the top surface 101b face each other is a vertical direction (up and down direction), and a direction perpendicular to the vertical direction is a 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 rotation shaft 112 is located on a vertical axis AX that passes through the center O of the bottom surface 101 a of the stirring vessel 101. The first rotating shaft 112 is connected to a driving source (not shown) (for example, a motor) and rotates by driving the driving source. The rotation speed of the first rotating shaft 112 (= the rotation speed of the first stirring jig 111) is appropriately adjusted within a range of 5 to 100 rpm, for example.

The arm portion 113 is located at a position higher than the lowermost portion 112a in the stirring tank 101 from the lowermost portion 112a, which is the lower end portion of the first rotating shaft 112, and in the rotational radius 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 at a position separated in a direction (perpendicular to the first rotating shaft 112). In addition, two arm portions 113 are attached to the first rotation shaft 112 so as to be positioned symmetrically in a direction perpendicular to the first rotation shaft 112. In addition, the 1st rotating shaft 112 and each arm part 113 may be comprised integrally, and may be comprised by joining of another member. Each arm portion 113 is configured to have a U-shaped cross section that protrudes downward as a whole as a result of extending upward in a curved and monotonous manner from the lowermost portion 112 a of the first rotating shaft 112. The first stirring jig 111 having the above-described configuration is also referred to as an anchor type because it looks like an anchor in the appearance.

FIG. 4 is a cross-sectional view showing another configuration of the first stirring jig 111. Each arm portion 113 of the first stirring jig 111 may be configured with a W-shaped cross section as a whole. That is, each arm portion 113 may have a shape that once falls downward from the lowermost portion 112a of the first rotating shaft 112 toward the outer side in the rotational radius direction and extends toward the uppermost portion 113a therefrom. 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. FIG. As shown in FIG. 5, the first stirring jig 111 includes an arm portion 113 having a shape that extends from the lowermost portion of the first rotating shaft 112 outward in the rotational radial direction and then bends upward. May be. 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 configured as a so-called anchor paddle type in which the area of the arm portion 113 is increased to improve the efficiency of stirring (watering). It may be.

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

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 rotating shaft 112 and the second rotating shaft 122 are parallel to each other. The second rotating shaft 122 is connected to a driving source (not shown) (for example, a motor) and rotates by driving the driving source. The rotation speed of the second rotating shaft 122 (= the rotating speed of the second stirring jig 121) is appropriately adjusted, for example, between 200 and 2000 rpm, and rotates at a speed higher than that of the first rotating shaft 112.

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

Here, the length along the vertical direction from the lowermost part of the arm part 113 of the first stirring jig 111 to the uppermost part 113a is defined as L (mm). 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 (equivalent to the lowermost portion 112a of the first rotating 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 portion 113 is curved to a position R further below the lowermost portion 112a of the first rotating shaft 112 and then extends upward toward the uppermost portion 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 of the vertical length (depth) of the stirring tank 101, more preferably 1/3 or more, and 1/2 or more. It is further desirable that

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

Further, the second stirring blade 123b of the second stirring jig 121 is positioned below the position A, and is vertically driven by the first stirring blade 123a by the rotation about the second rotation shaft 122. It is composed of stirring blades that cause the resin drawn downward to flow in a direction perpendicular to the second rotation shaft 122. The agitating blade is composed of a turbine type agitating blade shown in FIG. 10 or a disk type (dissolving) agitating 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. The dope composition includes a resin, a solvent, and an additive. Here, a pellet-shaped resin such as an acrylic resin, a cycloolefin resin, or a polyarylate resin is used as the resin. As the solvent, methylene chloride, chloroform or the like is used. As the additive, fine particles (mat agent), a plasticizer, or the like is used. Since the specific gravity of the pellet-shaped resin is smaller than 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, Most of the water floats on the solvent level.

When the first stirring jig 111 and the second stirring jig 121 are respectively rotated to stir the resin and the solvent, first, the first stirring blade 123a of the second stirring jig 121 rotates to rotate in the solvent. Thus, a flow of the resin in the vertical direction (vertical direction in FIG. 3), that is, a flow of drawing the resin from the upper side to the lower side occurs. The flow of the resin drawn vertically downward by the first stirring blade 123a by the rotation of the second stirring blade 123b in the direction perpendicular to the second rotation shaft 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 portion 113 of the first stirring jig 111 rotates around the first rotation shaft 112, the resin and solvent flowing in the horizontal direction are sheared by the second stirring blade 123b ( It can be stirred in the depth direction in FIG.

With such agitation by the first agitating blade 123a (vertical direction) and agitation by the second agitating blade 123b and the arm portion 113 (horizontal direction, shear direction), the resin and solvent in the agitation tank 101 are uniform. And it stirs efficiently and stirring nonuniformity is reduced. Thereby, since the viscosity of the dope prepared by stirring is stabilized, film thickness unevenness can be reduced when an optical film is formed using the dope. In addition, since the resin can be uniformly stirred in the stirring tank 101, it becomes difficult to cause poor dissolution such as aggregation of the resin in the stirring tank 101 to form an aggregate (undissolved material), which is caused by the undissolved material. The generation of bright spot foreign matter can also be reduced.

Also, if the dope viscosity is unstable, it is necessary to adjust the dope viscosity (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. However, in this embodiment, since the dope viscosity is stabilized by uniform stirring, it is possible to avoid the reduction in productivity of the optical film described above.

Further, 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, if Δ> 0.1, the resin floats on the liquid surface of the solvent due to the specific gravity difference. As a result, spalling is likely to occur. However, in the present embodiment, the unevenness of stirring is reduced as described above, and the inside of the stirring tank 101 can be uniformly stirred. Therefore, even if the condition of Δ> 0.1, the generated spatter is reduced by stirring. , Generation of undissolved substances can be suppressed. As a result, in the optical film formed, the bright spot foreign matter resulting from the undissolved material can be reduced. If the specific gravity difference between the solvent and the resin is too large, the resin is less likely to flow below the solvent even when stirring in the vertical direction, and there is a concern that the effect of reducing stirring unevenness will be reduced. For this reason, 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 satisfying 0.1 <Δ <0.5 are selected to prepare a dope and form an optical film.

Incidentally, the specific gravity of polymethyl methacrylate resin (PMMA; PolymethylPomethacrylate), which is an acrylic resin, is 1.17, the specific gravity of cycloolefin resin is 1.01, and the specific gravity of polyarylate resin is 1.21. . The specific gravity of methylene chloride is 1.32 and the specific gravity of chloroform is 1.48. Therefore, since any of the above resins satisfies 0.1 <Δ <0.5 with any of the above solvents, the resin and the solvent are used to stir by the method of this embodiment. In this way, by forming a dope and forming an optical film, it is possible to reduce film thickness unevenness and bright spot foreign matter caused by uneven stirring. It can be said that the more desirable range of the specific gravity difference Δ is 0.1 <Δ <0.31 from the minimum value and the maximum value of the specific gravity difference in the combination of each resin and each solvent.

In addition, in the configuration using two stirring blades that generate the upstream and downstream as in the 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 flow from the lower side to the upper side. The resin may flow vigorously and the resin may adhere to the top surface (lid portion) of the stirring tank. In this respect, in the present embodiment, since the agitating blade (first agitating blade 123a) that generates the upstream and downstream and the agitating blade (second agitating blade 123b) that generates the horizontal flow are used, The resin and the solvent can be uniformly stirred in the stirring tank 101 while moderately suppressing the flow of the resin. Therefore, the resin hardly adheres to the top surface 101b of the stirring tank 101.

Moreover, in this embodiment, the 1st stirring blade 123a located in the uppermost part among the several stirring blades of the 2nd stirring jig 121 is located above it including the position A, and 2nd Since the first agitating blade 123b is positioned below the position A, the first agitating blade 123a is rotated between the second agitating blade 123b and the arm portion 113 of the first agitating jig 111. The resin can be reliably drawn, and the drawn resin and solvent can be reliably stirred 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, the first stirring blade 123a located at the top of the plurality of stirring blades of the second stirring jig 121 is a paddle-type or propeller-type stirring blade, and therefore the first stirring blade 123a rotates. Thus, the flow in the vertical direction in the stirring tank 101, in particular, the flow of the resin from the upper side to the lower side can be reliably generated. On the other hand, the second stirring blade 123b located below the first stirring blade 123a is a turbine-type or disk-type stirring blade, so that the rotation of the second stirring blade 123b causes the horizontal resin flow to flow. It can surely occur.

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, the second stirring jig 121 can be positioned in a part of the space as in the present embodiment. And it becomes possible to implement | achieve the structure which stirs resin and a solvent in the stirring tank 101 uniformly by rotation of the 1st stirring jig 111 and rotation of the 2nd stirring jig 121. FIG.

Incidentally, FIG. 12 is a cross-sectional view showing another configuration of the second stirring jig 121. The second stirring jig 121 may further include a third stirring blade 123c in addition to the first stirring blade 123a and the second stirring blade 123b described above. The third agitating blade 123c is located one lower than the second agitating blade 123b, and, like the second agitating blade 123b, the turbine-type agitating blade shown in FIG. 10 or the disk-type agitating blade shown in FIG. Consists of.

The second stirring jig 121 has three stirring blades (a first stirring blade 123a, a second stirring blade 123b, and a third stirring blade 123c). The third 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 used as the second stirring blade 123b. And the third stirring blade 123c is rotated to flow in the horizontal direction in a wide range in the vertical direction (depth direction) in the stirring tank 101, and the resin and the solvent are moved in the vertical direction by the rotation of the arm portion 113. It can be stirred in the shear direction over a wide range. That is, the rotation of the third agitating blade 123 c causes a horizontal resin flow even at a deeper position in the agitation tank 101, and the agitation in the shearing direction due to the rotation of the arm portion 113 can be performed. Thereby, uniform stirring in the stirring tank 101 can be efficiently performed in a shorter time.

Although the case where the number of the arm parts 113 of the first stirring jig 111 is two has been described above, the number of the arm parts 113 may be one, or may be three or more. . However, in consideration of the efficiency of stirring, it is desirable that the number of arm portions 113 is plural.

Further, when the plurality of arm portions 113 are provided on the first rotation shaft 112, the plurality of arm portions 113 are equiangularly 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 unevenness of stirring 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 intervals of 180 °. In addition, 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 the four 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 90 ° intervals.

Moreover, although the case where the number of the 2nd stirring jig 121 in the stirring tank 101 is two was demonstrated above, the number of the 2nd stirring jig 121 may be one, There may be three or more. However, in consideration of the efficiency of stirring, the number of the second stirring jigs 121 is preferably plural.

Further, when a plurality of second stirring jigs 121 are provided, the second stirring jig 121 is provided in the stirring tank 101 within a plane perpendicular to the first rotation shaft 112 of the first stirring jig 111. A plurality of equiangular intervals around the first rotating shaft 112 is desirable from the viewpoint of further reducing unevenness in stirring 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, the second stirring jigs 121 are arranged around the first rotation shaft 112 at intervals of 180 °. It is desirable. Further, when the three second stirring jigs 121 are provided in the stirring tank 101, it is desirable that the second stirring jigs 121 are arranged around the first rotation shaft 112 at intervals of 120 °. Further, when four second stirring jigs 121 are provided in the stirring tank 101, it is desirable that the second stirring jigs 121 are arranged around the first rotation shaft 112 at 90 ° intervals. Note that the number of the second stirring jigs 121 may be the same as or different from the number of the arm portions 113 of the first stirring jig 111.

〔resin〕
In the present embodiment, any of acrylic resins, cycloolefin resins, and polyarylate resins can be used as the resin used for manufacturing the optical film, that is, the resin that is added to the stirring tank 101 and stirred and mixed with the solvent. .

<Acrylic resin>
The (meth) acrylic resin preferably has a Tg (glass transition temperature) of 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 Tg is 115 ° C. or higher, the durability of the optical film is improved. Although the upper limit of Tg of the (meth) acrylic resin is not particularly limited, it is preferably 170 ° C. or less from the viewpoint of moldability.

As the (meth) acrylic resin, any appropriate (meth) acrylic resin can 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- (Meth) acrylic acid copolymer, (meth) methyl acrylate-styrene copolymer (MS resin, etc.), a polymer having an alicyclic hydrocarbon group (for example, methyl methacrylate-cyclohexyl methacrylate copolymer, Methyl methacrylate- (meth) acrylate norbornyl copolymer, etc.). Preferable examples include C1-6 alkyl poly (meth) acrylates such as poly (meth) acrylate methyl. More preferred is a methyl methacrylate-based resin containing methyl methacrylate as a main component (in the range of 50 to 100% by mass, preferably 70 to 100% by mass). 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, for example, Acrypet VH and Acrypet VRL20A, Dianal BR52, BR80, BR83, BR85, BR88 (manufactured by Mitsubishi Rayon Co., Ltd.), KT75 (manufactured by Electrochemical Industry Co., Ltd.) ), Delpet 60N, 80N (manufactured by Asahi Kasei Chemicals Corporation), (meth) acrylic resin having a ring structure in the molecule described in JP-A-2004-70296, by intramolecular crosslinking or intramolecular cyclization reaction. Examples include the obtained high Tg (meth) acrylic resin system.

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 2000-230016, JP 2001-151814, JP 2002-120326, JP 2002-254544, and JP 2005. No. 146084 and the like.

Also, as the (meth) acrylic resin, an acrylic resin having an unsaturated carboxylic acid alkyl ester structural unit and a glutaric anhydride structural unit 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-. Examples described in JP-A-131898, JP-A-2006-206881, JP-A-2006-265532, JP-A-2006-283013, JP-A-2006-299905, JP-A-2006-335902, and the like. It is 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. -337374, JP-A-2006-337493, JP-A-2006-337569, and the like.

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

In the formula, each of R ¹ to R ⁴ independently represents a hydrogen atom, a hydrocarbon group, a halogen atom, a hydroxy group, a carboxy group, an acyloxy group, an aryloxycarbonyl group, an alkoxycarbonyl group, an alkoxy group, a cyano group, or an amide group. Substituted with an imide group, a silyl group, or a polar group (that is, a halogen atom, a hydroxy group, an acyloxy group, an aryloxycarbonyl group, an alkoxycarbonyl group, an alkoxy group, a cyano group, an amide group, an imide group, or a silyl group) Hydrocarbon group.

However, two or more of R ¹ to R ⁴ may be bonded to each other to form an unsaturated bond, monocycle or polycycle, and this monocycle or polycycle has a double bond. Alternatively, an aromatic ring may be formed. R ¹ and R ² , or R ³ and R ⁴ may form an alkylidene group. p and m are integers of 0 or more.

In the 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 carbon atoms, and particularly preferably 1 to 2 carbon atoms.

R ² and R ⁴ are each a hydrogen atom or a monovalent organic group, and at least one of R ² and R ⁴ preferably represents a polar group having a polarity other than a hydrogen atom or a hydrocarbon group, and m is 0 An integer of ˜3, p is an integer of 0 to 3, more preferably m + p = 0 to 4, more preferably 0 to 2, particularly preferably m = 1 and p = 0.

The specific monomer with m = 1 and p = 0 is preferable in that the resulting cycloolefin resin has a high glass transition temperature and excellent mechanical strength. The glass transition temperature 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. These polar groups have a linking group such as a methylene group. It may be bonded via.

In addition, a hydrocarbon group in which a divalent organic group having polarity 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 can also be 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, a monomer in which at least one of R ² and R ⁴ is a polar group represented by the formula — (CH ₂ ) _n COOR is obtained by using a cycloolefin resin having a high glass transition temperature, a low hygroscopic property, and various materials. It is preferable at the point from which it has the outstanding adhesiveness.

In the above formula relating to the specific polar group, R is a hydrocarbon group having 1 to 12 carbon atoms, more preferably 1 to 4 carbon atoms, particularly preferably 1 to 2 carbon atoms, and preferably 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 4-20, and more preferably 5-12.

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

A preferred molecular weight of the cycloolefin resin is an intrinsic viscosity [η] _inh of 0.2 to 5 cm ³ / g, more preferably 0.3 to 3 cm ³ / g, particularly preferably 0.4 to 1.5 cm ³ / g. The number average molecular weight (Mn) in terms of polystyrene measured by gel permeation chromatography (GPC) is 8000 to 100,000, more preferably 10,000 to 80,000, particularly preferably 12,000 to 50,000, and the weight average molecular weight (Mw). Is from 20,000 to 300,000, more preferably from 30,000 to 250,000, particularly preferably from 40,000 to 200,000.

Inherent viscosity [η] _inh , number average molecular weight and weight average molecular weight are within the above ranges, so that heat resistance, water resistance, chemical resistance, mechanical properties of the cycloolefin resin, and molding of the optical film of the present embodiment And is good.

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. The case where 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 or printing.

On the other hand, when Tg is 350 ° C. or lower, the case where the molding process becomes difficult can be avoided, and the possibility that the resin deteriorates due to heat during the molding process can be reduced.

For the cycloolefin resin, a specific hydrocarbon resin described in, for example, Japanese Patent Application Laid-Open No. 9-221577 and Japanese Patent Application Laid-Open No. 10-287732, or a known heat can be used without departing from the effect of the present embodiment. Plastic resins, thermoplastic elastomers, rubbery polymers, organic fine particles, inorganic fine particles, etc. may be blended. Specific wavelength dispersing agents, sugar ester compounds, antioxidants, peeling accelerators, rubber particles, plasticizers, ultraviolet rays An additive such as an absorbent may be included.

Moreover, as the cycloolefin resin, a commercially available product can be preferably used. Examples of commercially available products are sold under the trade names Arton (registered trademark) G, Arton F, Arton R, and Arton RX by JSR Corporation. Moreover, ZEONOR (registered trademark) ZF14, ZF16, ZEONEX (registered trademark) 250 or ZEONEX 280 is commercially available from ZEON Corporation, 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 a bisphenol represented by the following formula (1), more preferably a bisphenol 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 To form an aliphatic ring or an 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. 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, preferably a fluorene ring which may have a substituent. Examples of —CR ₁ R ₂ — that forms 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 fluorenediyl group represented by the following formula.

R in the general formulas (1) and (1 ′) may independently be an alkyl group having 1 to 5 carbon atoms or an aryl group having 6 to 10 carbon atoms. n is independently an 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, 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- Preferred are isopropylidene-containing bisphenols such as 4-hydroxyphenyl) propane (TMBPA).

Examples of bisphenols where L is —S—, —SO— or —SO ₂ — include 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) Sulfide, bis (3-ethyl-4-hydroxyphenyl) sulfide, 2,4-dihydro Shi diphenyl sulfone and the like. Examples of bisphenols in which L is —O— include 4,4′-dihydroxydiphenyl ether. Examples of bisphenols in which L is —CO— include 4,4′-dihydroxydiphenyl ketone.

Examples of bisphenols in which L is —CR ₁ R ₂ — and R ₁ and R ₂ are bonded to form an aliphatic ring include 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 include 9,9-bis (3-methyl-4-hydroxyphenyl) Bisphenols having a fluorene skeleton such as fluorene (BCF) and 9,9-bis (3,5-dimethyl-4-hydroxyphenyl) fluorene (BXF) are included.

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 or improving the adhesion of the film to the metal, for example, a sulfur atom (—S—, —SO— or —SO ₂ —) is present in the main chain. Bisphenols contained are preferred. From the viewpoint of enhancing the heat resistance of the film, for example, bisphenols containing a sulfur atom in the main chain and bisphenols having a cycloalkylene skeleton are preferred. From the viewpoint of reducing the birefringence of the film or improving the wear resistance, bisphenols having a fluorene skeleton are preferred.

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 having an isopropylidene group is 10/90 to 90/10 (molar ratio), preferably 20/80 to 80/20 (molar ratio).

The polyarylate may further contain an aromatic polyhydric alcohol component unit other than the aromatic dialcohol component as long as the effects of the present embodiment are not impaired. Examples of the aromatic polyhydric alcohol component 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, 4,4′-tetrahydroxybenzophenone, 4- [bis (4-hydroxyphenyl) methyl] -2-methoxyphenol, tris (3-methyl-4-hydroxyphenyl) methane and the like are included. The content ratio of these aromatic polyhydric alcohol component units can be appropriately set according to the required characteristics, but is 5 for example with respect to the total of the aromatic dialcohol component unit and the other aromatic polyhydric alcohol component units. It may be less than mol%.

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

From the viewpoint of enhancing the mechanical properties of the film, a mixture of terephthalic acid and isophthalic acid is preferable. 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 still more preferably 50/50. When the content ratio of terephthalic acid is in the above range, a polyarylate having a sufficient degree of polymerization is easily obtained, and a film having sufficient mechanical properties is easily obtained.

The polyarylate may further contain an aromatic dicarboxylic acid component unit 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 aromatic dicarboxylic acid component units other than terephthalic acid and isophthalic acid can be appropriately set according to the required properties, but the total of terephthalic acid component, isophthalic acid component unit and other aromatic dicarboxylic acid component units For example, it may 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., 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 DSC 6220 manufactured by Seiko Instruments Inc. as a measuring device, it can be measured under the conditions of a 10 mg polyarylate sample 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. In order to increase the glass transition temperature, for example, it is preferable to include “units derived from bisphenols containing a sulfur atom in the main chain” as aromatic dialcohol component units.

(Intrinsic viscosity)
The intrinsic viscosity of the polyarylate is preferably from 0.3 to 1.0 dl / g, more preferably from 0.4 to 0.9 dl / g, still more preferably from 0.45 to 0.8 dl / g. More preferably, it is 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 a certain level or more, and a film having sufficient mechanical properties and heat resistance is easily obtained. When the intrinsic viscosity of the polyarylate is 1.0 dl / g or less, an excessive increase in the solution viscosity during film formation can be suppressed.

The intrinsic viscosity can be measured in accordance with ISO1628-1. Specifically, a solution in which a polyarylate sample is dissolved 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 type viscosity tube.

The polyarylate production method 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 (W. M. EARECKSON, J. Poly. Sci. XL 399, 1959, Japanese Patent Publication No. 40-1959).

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

〔solvent〕
In the present embodiment, as a solvent used for manufacturing an optical film, that is, a solvent for dissolving the above-described resin in a stirring tank of a stirring device, for example, dichloromethane (methylene chloride, methylene chloride), chloroform, ethanol, butanol, isopropanol N-methyl-2-pyrrolidone, 1,3-dimethylimidazolidinone, N, N-dimethylacetamide, N, N-diethylacetamide, N, N-dimethylformamide, N, N-diethylformamide, N-methylcaprolactam , Hexamethylphosphoramide, tetramethylene sulfone, dimethyl sulfoxide, m-cresol, phenol, p-chlorophenol, 2-chloro-4-hydroxytoluene, diglyme, triglyme, tetraglyme, dioxane, γ-buty Lactone, 1,3-dioxolane, cyclohexanone, cyclopentanone, 1,4-dioxane, epsilon-caprolactam, tetrahydrofuran (THF) or the like can be used, can be used by mixing one or more of them. In addition to these solvents, a poor solvent such as hexane, heptane, benzene, toluene, xylene, chlorobenzene, 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, plasticizer, ultraviolet absorber, antioxidant, sugar ester compound, retardation adjusting agent, light stabilizer, antistatic agent, release agent A thickener or the like may be used. Hereinafter, only main additives will be described.

<Fine particles (matting agent)>
The optical film of this embodiment preferably contains a matting agent in order to impart irregularities to the film surface during film formation, ensure slipperiness, and achieve a stable winding shape. By containing the matting agent, when the produced optical film is handled, it is possible to suppress damage and deterioration of transportability.

Examples of the matting agent include fine particles of inorganic compounds and fine particles of resin. Examples of fine particles of inorganic compounds include 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. Fine particles containing silicon are preferable in terms of low turbidity, and silicon dioxide is particularly preferable.

The average primary particle size of the fine particles is preferably in the range of 5 to 400 nm, and more preferably in the range of 10 to 300 nm. These may be mainly contained as secondary aggregates having a particle size of 0.05 to 0.3 μm. If the particles have an average particle size of 80 to 400 nm, the primary particles are not aggregated. 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.

Silicon dioxide fine particles are commercially available under the trade names of, for example, Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (manufactured by Nippon Aerosil Co., Ltd.). .

Zirconium oxide fine particles are commercially available, for example, under the trade names Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.) and can be used.

Examples of resin fine particles include silicone resin, fluororesin and acrylic resin. Silicone resins are preferred, and those having a three-dimensional network structure are particularly preferred. For example, these are commercially available under the trade names of Tospearl 103, 105, 108, 120, 145, 3120 and 240 (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 reducing the friction coefficient while keeping the haze of the optical film low.

<Plasticizer>
A polyester resin can be used as a 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 structural unit (the structural unit derived from the dicarboxylic acid) is derived from the aromatic dicarboxylic acid, and the diol structural unit (derived from the diol). 70% or more of the structural unit is derived from an aliphatic diol.

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 structural unit derived from the aliphatic diol is 70% or more, preferably 80% or more, and more preferably 90% or more. Two or more polyester resins may be used in combination.

Examples of aromatic dicarboxylic acids 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, Examples 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 without departing from the object of the present invention.

Examples of the aliphatic diol include ethylene glycol, 1,3-propylene diol, 1,4-butanediol, 1,4-cyclohexanedimethanol, 1,6-hexanediol, 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 esterification method or 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 compounds such as antimony trioxide and antimony pentoxide, germanium compounds such as germanium oxide, titanium compounds such as titanium acetate, and aluminum compounds such as aluminum chloride. Although it can, it is 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-naphthalene dicarboxylate resin, polyethylene-2, 6-naphthalene dicarboxylate-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-naphthalene dicarboxylate. Resin.

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

〔Example〕
Hereinafter, specific examples of the present invention will be described, 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 apparatuses 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 speed. It is a position 500 mm above the uppermost portion 113a of the arm portion 113 of the jig 111, the height from the bottom surface 101a of the uppermost portion 113a of the arm portion 113 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 (separation distance in the direction perpendicular to the first rotation shaft 112) is 2050 mm, and the distance between the first rotation shaft 112 and the second rotation shaft 122 is The distance was 750 mm.

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

<Preparation of optical film 1>
(Synthesis of acrylic resin 1 (copolymer A1))
As monomers, 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 are mixed. 0.04 parts by mass of 2,2-bis (4,4-ditertiary 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. Charged continuously at 1.67 L / hr. At this time, the temperature of the complete mixing reactor was adjusted to 135 ° C. Next, the polymer solution continuously discharged from the polymerization reactor is supplied to a vent type screw type extruder having a reduced pressure of 2.7 to 4.0 kPa to remove volatile matter, and the pellet-shaped copolymer A1 is removed. Got. The constituent ratio of the monomer unit in the copolymer A1 was 90 mol% for the styrene monomer, 10 mol% for the acrylic acid monomer, and the weight average molecular weight was 300,000.

The following components were stirred using the stirrer A prepared above and dissolved sufficiently with heating to prepare a dope 1. At this time, the stirring speed (rotation speed) of the first stirring jig of the stirring device A was 50 rpm, and the stirring speed (rotation speed) of the second stirring jig was 500 rpm. Moreover, the stirring time in the stirring apparatus 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 steel band support at a temperature of 22 ° C. and a width of 2 m using a belt casting apparatus. The solvent was evaporated on the stainless steel band support until the residual solvent amount reached 50%, and the obtained film-like material was peeled off from the stainless steel band support with a peeling tension of 162 N / m.

Next, the peeled film-like product was dried at a drying temperature of 135 ° C. while evaporating the solvent at 35 ° C. and stretching it 1.25 times in the width direction (TD direction) by tenter stretching. The residual solvent amount at the start of stretching by zone stretching was 20.0%, and the residual solvent amount at the start of stretching by tenter 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 conveying a drying zone at 120 ° C. and 140 ° C. with a number of rollers. The obtained film was slit to a width of 1.5 m and subjected to a knurling process having a width of 10 mm and a height of 5 μm at both ends of the film, 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.

<Preparation of optical films 2 to 6>
Optical films 2 to 6 were respectively prepared in the same manner as the optical film 1 except that the stirrers B to F were used instead of the stirrer A to stir the resin and prepare dope.

<Preparation of optical film 7>
(Synthesis of cycloolefin resin COP1)
As the cycloolefin resin, a 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, and 2. 3 g and 100 g of toluene were charged into a nitrogen-substituted reaction vessel and heated to 80 ° C. To this was added 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), and the mixture was reacted at 80 ° C. for 3 hours. Coalescence was obtained. Next, the obtained ring-opening copolymer solution was put in an autoclave, and 100 g of toluene was further added. A hydrogenation catalyst, RuHCl (CO) [P (C ₆ H ₅ )] _3, was added at 2500 ppm based on the monomer charge, the hydrogen gas pressure was adjusted to 9-10 MPa, and the reaction was carried out at 160-165 ° C. for 3 hours. went. After completion of the reaction, a hydrogenated product was obtained by precipitation in a large amount of methanol solution. Cycloolefin resin COP1, which is a hydrogenated product of the obtained ring-opening polymer, has a glass transition temperature (Tg) = 167 ° C., a weight average molecular weight (Mw) = 13.5 × 10 ⁴ , and 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 Gorey 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) stirred in the stirrer A. Further, the particles were dispersed by an attritor so that the secondary particles had a predetermined particle size. This was filtered through Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle additive solution.

(Preparation of main dope)
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 addition liquid were added to the stirring apparatus A containing dichloromethane while stirring. The resin was dissolved while heating and stirring, and this was dissolved in Azumi Filter Paper No. The main dope was prepared by filtration using 244. In addition, the stirring conditions in the stirring apparatus A are the same as the production of the optical film 1.
<Composition of main dope>
Cycloolefin resin COP1 100 parts by mass Methylene chloride 200 parts by mass Ethanol 10 parts by mass Fine particle additive solution 10 parts by mass

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

Next, the peeled film-like material was dried at a drying temperature of 160 ° C. while evaporating the solvent at 35 ° C. and stretching it 1.25 times in the width direction (TD direction) by tenter stretching. The residual solvent amount when starting stretching by zone stretching was 10.0%, and the residual solvent amount when starting stretching by a tenter 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 a 120 ° C. drying zone was conveyed by a number of rollers. The obtained film was slit to a width of 1.5 m and subjected to a knurling process having a width of 10 mm and a height of 5 μm at both ends of the film, and then wound on 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>
As a solvent to be used, optical film 8 was prepared in the same manner as optical film 1 except that the dope was prepared by stirring using chloroform in the same amount as methylene chloride instead of methylene chloride.

<Preparation of optical film 9>
An optical film 9 was produced in the same manner as the production of the optical film 1 except that the dope 2 having the following composition including 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

<Preparation of optical film 10>
(Production of 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 the aromatic dialcohol component 35.6 parts by weight, 1,2-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 regulator Was dissolved, and 0.34 parts by weight of a polymerization catalyst (tributylbenzylammonium chloride) was added and stirred.

Meanwhile, 26.8 parts by weight of an equal 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 with 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 to the system to stop the polymerization reaction, and the organic phase and the aqueous phase were separated.

The obtained organic phase was washed with twice the amount of ion-exchanged water of the organic phase for each washing, and then the operation of separating the organic phase and the aqueous phase was repeated. The washing was terminated when the electric conductivity of the washing water became less than 50 μS / cm. The organic phase after washing was put into a hot water tank equipped with a homomixer at 50 ° C., and methylene chloride was evaporated to obtain a powdery polymer. Furthermore, 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 put into a stirrer A and gradually heated to 45 ° C. with stirring to be completely dissolved. The obtained solution was used as Azumi filter paper No. manufactured by Azumi Filter Paper Co., Ltd. Filtration using 244 gave a polymer solution.

The obtained polymer solution was uniformly cast on a stainless belt of a belt casting apparatus. A stainless steel belt having a length of 20 m was used. The surface temperature of the stainless steel belt is 35 ° C. and 35 ° C. wind is applied to the casting film to evaporate the solvent until the residual solvent amount is 38%, and then the film is peeled off from the stainless steel belt to obtain a film-like material. It was.

The obtained film-like material was stretched 1.2 times at 170 ° C. in the MD direction using the peripheral speed difference 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 transported in a drying apparatus at 125 ° C. by a number of rolls, and then subjected to knurling with a width of 15 mm and a height of 10 μm at both ends in the width direction of the film. As a result, an optical film 10 having a film thickness of 40 μm was obtained.

<Preparation of optical films 11-13>
Optical films 11 to 13 were respectively produced in the same manner as the optical film 1 except that the stirrers G to I were used instead of the stirrer A to stir the resin and prepare dope.

<Preparation of optical film 14>
As a solvent to be used, optical film 14 was prepared in the same manner as optical film 1 except that instead of methylene chloride, the same amount of THF (tetrahydrofuran) as methylene chloride was used for stirring 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 using a micrometer at intervals of 10 mm in the width direction of the film, and the difference between the maximum value and the minimum value of each film thickness ( μm) was defined as film thickness unevenness. In addition, 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, the level is problematic 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 (crossed Nicols), light is applied from the outside of one polarizing plate, and the outside of the other polarizing plate is observed with a transmission microscope. Observation was performed at a magnification of 50 times, and the number of foreign matters (bright spot foreign matter) that appeared to shine in an area of 25 cm ² was counted and converted to the number per 1 cm ² . And the said observation was performed 10 places per sample, the number of foreign materials was measured, and the average value was made into the number of final foreign materials. And the foreign material was evaluated based on the following evaluation criteria.
"Evaluation criteria"
A: The number of foreign matters is 0.15 or less per 1 cm ² .
○ The number of foreign matters is larger than 0.15 per 1 cm ^{2 and} equal to or smaller than 0.20.
Δ: The number of foreign matters is greater than 0.20 and less than or equal to 0.25 per cm ² .
X: The number of foreign matters is larger than 0.25 per 1 cm ^{2 and not} larger than 0.35, but there is a problem in actual use.
XX: The number of foreign matters is larger than 0.35 per cm ² , which is a considerable problem in actual use.

Table 2 shows the resin, solvent, stirring device used for the production of each of the 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 matters are poor. This is because the dope used for forming the optical film 11 was prepared using the stirring device G. However, in the stirring device G, as shown in FIG. Since the uppermost first stirring blade 123a is located at a position lower than the position A, which is 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.

Also, in the optical film 12, the film thickness unevenness and the evaluation of foreign matters are poor. This is because the dope used for forming the optical film 12 was prepared by using the stirring device H. However, as shown in Table 1, in the stirring device H, the outermost portion of the second stirring jig 121 was used. Since the upper first stirring blade 123a is composed of a disk-type stirring blade that creates a flow in a direction perpendicular to the second rotating shaft 122, the resin having a small specific gravity and floating above the solvent is also used. This is probably because the first agitating blade 123a could not efficiently draw downward, and as a result, uneven stirring occurred.

Also, in the optical film 13, the film thickness unevenness and the evaluation of foreign matters are poor. This is because the dope used for forming the optical film 13 was prepared by using the stirring device I. In the stirring device I, as shown in FIG. The stirring blade is composed only of the first stirring blade 123a, and the resin drawn downward by the first stirring blade 123a cannot be stirred in the shear direction with the arm portion 113, and as a result, This is thought to be due to large unevenness in stirring.

Also, in the optical film 14, the film thickness unevenness and the evaluation of the foreign matter are poor. This is because the resin used in the formation of the optical film 13 has a specific gravity greater than that of the solvent and is heavier. Therefore, even if the resin is stirred in the stirring tank 101, the resin does not flow upward, resulting in uneven stirring. It is done.

On the other hand, in the optical films 1 to 10, the film thickness unevenness and the evaluation of foreign matters are both good. This is because the dope used in the production 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 treatment was performed. The first stirring blade 123a of the tool 121 includes a position A and is positioned above this, and is configured with a stirring blade (propeller type, paddle type) that causes the resin to flow in the vertical direction. (2) The second stirring blade 123b is configured by a stirring blade (disk type, turbine type) that is positioned below the position B and causes a flow in a direction perpendicular to the second rotation shaft 122. This is considered to be because uniform stirring is achieved in the stirring tank 101. That is, according to the above (1) and (2), the vertical stirring by the first stirring blade 123a and the shearing stirring by the second stirring blade 123b and the arm portion 113 are performed, so that the solvent and the resin 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 were uniformly and efficiently stirred, and the stirring unevenness was reduced.

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

<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 arm portions are provided at equal intervals of 120 degrees around the first rotation axis. 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 arm portions are provided at equal intervals of 90 degrees around the first rotation axis.

<Preparation of optical films 15 to 17>
Optical films 15 to 17 were respectively prepared in the same manner as the optical film 1 except that the stirrers J to L were used instead of the stirrer A to stir the resin and prepare 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 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 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 at equal intervals of 120 degrees around the second rotation axis. The stirring device O has the same configuration as the stirring device A except that the number of 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 at equal intervals of 90 degrees around the second rotation axis.

<Preparation of optical films 18-20>
Optical films 18 to 20 were respectively prepared in the same manner as the optical film 1 except that the dope was prepared by stirring the resin and the like using the stirring devices M to O instead of the stirring device A.

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

The stirring device J used for forming the optical film 15 has fewer arm portions 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 stirring devices J and M are not substitute for satisfying the above conditions (1) and (2). Therefore, in the optical films 15 and 18, the film thickness unevenness and the evaluation of foreign matters are lower than those of the optical film 1, but the level is not problematic in actual use, and the stirring unevenness J and M are also reduced. It can be said that the effect is obtained.

In addition, since the stirring devices K and L used in the production of the optical films 16 to 17 have more arms than the stirring device A, the stirring efficiency is further improved compared to the stirring device A, and uneven stirring is caused. It is considered that the film thickness was further reduced, and the evaluation of film thickness unevenness and foreign matter was further improved.

In addition, the stirring devices N and O used in the production of the optical films 19 to 20 have more second stirring jigs than the stirring device A, so that the stirring efficiency is further improved compared to the stirring device A. It is considered that the unevenness of stirring was further reduced, and the evaluation of unevenness of film thickness and foreign matters was further improved.

[Supplement]
Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the invention.

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

1. A method for producing an optical film by a solution casting method,
A stirring preparation step of preparing a dope by stirring at least a resin and a solvent in a stirring tank;
A casting step of casting the dope prepared in the stirring preparation step on a 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 includes 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, and the first stirring jig is moved in the stirring tank. An arm portion extending from the first rotation axis to a position away from the first rotation axis in a rotational radius direction above the lowermost portion;
The second agitating jig is arranged such that the second agitation jig is aligned along the vertical direction with the second rotation axis extending in the vertical direction so as to pass through the space between the first rotation axis and the arm portion. Having at least two stirring blades attached to two rotating shafts,
The length along the vertical direction of the arm portion of the first stirring jig is L, and among the at least two stirring blades of the second stirring jig, the uppermost stirring blade and one lower side thereof When the stirring blades located at 1 are respectively the first stirring blade and the second stirring blade,
The first stirring blade is located above and including a position vertically lowered by (1/3) L from the uppermost portion of the arm portion of the first stirring jig, and the second stirring blade It is composed of a stirring blade that causes a vertical flow of the resin by rotation about the rotation axis of
The second agitating blade is located below a position vertically lowered by (1/3) L from the uppermost part of the arm portion of the first agitating jig, and the second rotating shaft is An optical system comprising: an agitating blade that causes a flow of the resin drawn vertically downward by the first agitating blade in a direction perpendicular to the second rotation axis by rotation about the center. A method for producing a film.

2. 0.1 <Δ <0.31
2. The method for producing an optical film as described in 1 above, wherein

3. 3. The method for producing an optical film as described in 1 or 2 above, wherein the solvent contains methylene chloride or chloroform.

4. 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. 5. The method for producing an optical film as described in any one of 1 to 4, wherein the second stirring blade is a turbine-type or disk-type stirring blade.

6. 6. The method of manufacturing an optical film as described in any one of 1 to 5, wherein the first stirring jig is configured by an anchor type or an anchor paddle type stirring blade.

7). The second stirring jig further includes a third stirring blade positioned one lower than the second stirring blade,
The method for producing an optical film as described in any one of 1 to 6, wherein the third stirring blade is a turbine-type or disk-type stirring blade.

8. The first stirring jig has a plurality of the arm portions at equiangular intervals around the first rotation axis in a plane perpendicular to the first rotation axis. The manufacturing method of the optical film in any one of 1-7.

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

10. 10. The method for producing an optical film as described in 8 or 9, wherein the equiangular intervals are 180 ° intervals.

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

DESCRIPTION OF SYMBOLS 101 Agitation tank 101a Garden surface 111 1st stirring jig 112 1st rotating shaft 112a Bottom part 113 Arm part 113a Top part 121 2nd stirring jig 122 2nd rotating shaft 123 Stirring blade 123a 1st stirring blade 123b 2nd stirring blade 123c 3rd stirring blade A position F optical film S1 stirring preparation process S2 casting process

Claims

A method for producing an optical film by a solution casting method,
A stirring preparation step of preparing a dope by stirring at least a resin and a solvent in a stirring tank;
A casting step of casting the dope prepared in the stirring preparation step on a 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 includes 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, and the first stirring jig is moved in the stirring tank. An arm portion extending from the first rotation axis to a position away from the first rotation axis in a rotational radius direction above the lowermost portion;
The second agitating jig is arranged such that the second agitation jig is aligned along the vertical direction with the second rotation axis extending in the vertical direction so as to pass through the space between the first rotation axis and the arm portion. Having at least two stirring blades attached to two rotating shafts,
The length along the vertical direction of the arm portion of the first stirring jig is L, and among the at least two stirring blades of the second stirring jig, the uppermost stirring blade and one lower side thereof When the stirring blades located at 1 are respectively the first stirring blade and the second stirring blade,
The first stirring blade is located above and including a position vertically lowered by (1/3) L from the uppermost portion of the arm portion of the first stirring jig, and the second stirring blade It is composed of a stirring blade that causes a vertical flow of the resin by rotation about the rotation axis of
The second agitating blade is located below a position vertically lowered by (1/3) L from the uppermost part of the arm portion of the first agitating jig, and the second rotating shaft is An optical system comprising: an agitating blade that causes a flow of the resin drawn vertically downward by the first agitating blade in a direction perpendicular to the second rotation axis by rotation about the center. A method for producing a film.
0.1 <Δ <0.31
The method for producing an optical film according to claim 1, wherein:
The method for producing an optical film according to claim 1, wherein the solvent contains methylene chloride or chloroform.
4. The method for producing an optical film according to claim 1, 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 disk-type stirring blade.
The method for producing an optical film according to any one of claims 1 to 5, wherein the first stirring jig includes an anchor type or an anchor paddle type stirring blade.
The second stirring jig further includes a third stirring blade positioned one lower than the second stirring blade,
The method for producing an optical film according to claim 1, wherein the third stirring blade is a turbine-type or disk-type stirring blade.
The first agitating jig has a plurality of the arm portions at equiangular intervals around the first rotation axis in a plane perpendicular to the first rotation axis. Item 8. A method for producing an optical film according to any one of Items 1 to 7.
A plurality of the second stirring jigs are provided at equal angular intervals around the first rotation axis in a plane perpendicular to the first rotation axis of the first stirring jig in the stirring tank. 9. 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 8 or 9, wherein the equiangular intervals are 180 ° intervals.