JP2020163627A - Producing method of optical film - Google Patents

Abstract

To provide a producing method of an optical film, capable of extruding smoothly even a resin pellet having a small friction coefficient and producing efficiently an optical film with excellent properties.SOLUTION: The producing method of the optical film includes a supply step of supplying pellet-shaped resin to a single-screw extruder and an extrusion step of extruding the supplied resin by the extruder, in which the extruder has a barrel and a screw, the extrusion step includes pushing the resin from an upstream side to a downstream side of the barrel by rotating the screw, the barrel includes a supply section, a compression section and a measuring section in this order from the upstream, an inner wall of the barrel in the supply section has a groove, the temperature TF of the inner wall of the barrel in the supply section is within a specific range, and a dynamic friction coefficient μF at the temperature TF between an inner wall material of the barrel in the supply section which has a shape of a surface without the groove and the pellet is 0.50 or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for producing an optical film.

One of the methods for manufacturing an optical film is a manufacturing method by melt extrusion molding. The general melt extrusion molding process includes a supply step of supplying the resin to the extruder and an extrusion step of extruding the supplied resin by the extruder. As the resin supplied in the supply process, a solid resin having a shape such as pellets that is easy to handle is used. In the extrusion process, the resin is melted in the extruder and the molten resin is extruded from the extruder. This is further passed through a molding device such as a die, whereby the resin is molded into the shape of a film.

Examples of general extruders include single-screw extruders and twin-screw extruders. In the production of an optical film by melt extrusion, a single-screw extruder is particularly preferably used from the viewpoint of being able to suppress denaturation due to shearing of the resin and making it a simple device. A general single-screw extruder includes a barrel having a cylindrical cavity and a screw provided in the barrel, and has a structure for pushing resin from the upstream side to the downstream side of the barrel by rotating the screw. ..

Various resins are mentioned as the resin used as the material of the optical film, and various new resins have been proposed in recent years. For example, as a resin having good properties such as high heat resistance and bending resistance, a resin containing a crystalline alicyclic structure-containing polymer has been proposed (Patent Document 1).

International Publication No. 2018/016442

Among the new resins proposed in recent years as materials for optical films, there are some that have unprecedented properties. For example, when the resin pellets containing the crystalline alicyclic structure-containing polymer described above are extruded by a single-screw extruder, the friction coefficient between the inner wall of the barrel and the pellets is small. Therefore, extrusion with a screw becomes insufficient, and it may be difficult to carry out the extrusion process. Specifically, there may be a problem that the flow velocity of the resin becomes unstable, the torque to the screw becomes excessive due to the blocking of the resin, and the extrusion operation is interrupted.

Therefore, an object of the present invention is to provide a method for producing an optical film, which can smoothly extrude even a resin pellet having a small friction coefficient and can efficiently produce a good optical film. There is.

As a result of studies for solving the above-mentioned problems, the present inventor has found that the above-mentioned problems can be solved by adopting a specific extruder and extrusion conditions used in the extrusion process, and complete the present invention. I let you.
That is, according to the present invention, the following are provided.

[1] A method for producing an optical film, comprising a supply step of supplying pellet-shaped resin to a single-screw extruder and an extrusion step of extruding the supplied resin by the extruder.
The extruder includes a barrel and a screw provided within the barrel, the extrusion step comprising pushing the resin from the upstream side to the downstream side of the barrel by rotating the screw.
The barrel includes a supply part, a compression part, and a measuring part in this order from the upstream.
The barrel has a groove in its inner wall at the supply section.
The temperature _TF of the inner wall of the barrel in the supply unit is the following formula (1):
Tg + 90 ° C ≤ T _F ≤ Tg + 180 ° C ... (1)
However, Tg is the glass transition temperature of the resin.
Wherein the temperature T _F, and having a surface shape not having grooves a barrel inner wall material in the supply unit, with the pellet, the dynamic friction coefficient mu _F is 0.50 or less, the production method.
[2] The manufacturing method according to [1], wherein the arithmetic mean roughness of the inner wall of the barrel in the supply section other than the groove is 0.5 μm or more and 10 μm or less.
[3] The screw has a gap inside the shaft in the supply section, and in the extrusion step, a fluid is present in the gap, and the surface temperature T of the shaft in the supply section is passed through the fluid. _S is expressed by the following equation (2):
_{Tg-10 ℃ ≦ T S ≦} Tg + 60 ℃ ··· (2)
The production method according to [1] or [2], which comprises adjusting to a range satisfying.
[4] The manufacturing method according to any one of [1] to [3], wherein the groove extends in a direction parallel to the axial direction of the extruder.
[5] The resin contains a polymer selected from the group consisting of an alicyclic structure-containing polymer, a cellulosic polymer, a polyethylene terephthalate polymer, an acrylic polymer, and a mixture thereof [1]. The production method according to any one of [4].

According to the method for producing an optical film of the present invention, smooth extrusion can be performed even with a resin pellet having a small friction coefficient, and a good optical film can be efficiently produced.

FIG. 1 is a side view schematically showing an example of an extruder used in the manufacturing method of the present invention. FIG. 2 is a cross-sectional view of the extruder 100 shown in FIG. 1 along a plane perpendicular to the central axis 130AX at a certain position in the supply unit 120F. FIG. 3 is a vertical cross-sectional view schematically showing a measuring device having a coefficient of dynamic friction μ _F.

Hereinafter, the present invention will be described in detail with reference to embodiments and examples. However, the present invention is not limited to the embodiments and examples shown below, and can be arbitrarily modified and implemented without departing from the scope of claims of the present invention and the equivalent scope thereof.

[1. Outline of manufacturing method of optical film]
The method for producing an optical film of the present invention includes a supply step of supplying pellet-shaped resin to a single-screw extruder and an extrusion step of extruding the supplied resin by an extruder. The extruder includes a barrel and a screw provided within the barrel. The extrusion process involves pushing the resin from the upstream side to the downstream side of the barrel by rotating the screw.

An example of an extruder used in the manufacturing method of the present invention, and a supply process and an extrusion process using the extruder will be described with reference to FIGS. 1 and 2.
FIG. 1 is a side view schematically showing an example of an extruder used in the manufacturing method of the present invention. FIG. 2 is a cross-sectional view of the extruder 100 shown in FIG. 1 along a plane perpendicular to the central axis 130AX at a certain position in the supply unit 120F. In FIG. 1, for convenience of illustration, members other than the screw 130 among the components of the extruder 100 show a vertical cross section cut along a plane passing through the central shaft 130AX of the screw 130.

In FIG. 1, the extruder 100 includes a barrel 120, a hopper 110 provided in an upstream portion of the barrel 120, and a screw 130 provided inside the barrel 120.

The hopper 110 is provided in a state of being fitted to the resin inlet 121 at the upstream portion of the barrel 120. The resin pellet 201 charged from the upper opening 111 of the hopper 110 flows out from the lower opening 112 of the hopper 110 and flows into the barrel 120 from the resin charging port 121, whereby the supply process is completed. The supplied pellet 201 is subjected to an extrusion process by the barrel 120 and the screw 130.

The screw 130 includes a shaft 131 and blades 132 provided around the shaft. As the screw 130 rotates about the central shaft 130AX, the pellet 201 in the barrel 120 is pushed out from the upstream to the downstream in the barrel. The blade 132 has a spiral structure and therefore the rotation of the screw 130 can push the contents of the barrel 120 downstream. In the example of FIG. 1, the spiral pitch of the blade 132 of the screw 130 is constant.

In the barrel 120 of the extruder, the supply unit 120F, the compression unit 120C, and the measuring unit 120M are defined in this order from the upstream side according to the thickness of the shaft 131 of the screw 130. The supply unit 120F is a unit that supplies the pellet 201 supplied into the barrel by the supply process to the compression unit, and the compression unit 120C pressurizes and heats the pellet 201, whereby the pellet 201 is made of a uniform molten resin. The measuring unit 120M is a portion for extruding the molten resin into a process further downstream from the extruder at a constant flow velocity.

In the compression unit 120C, the shaft 131 has a tapered shape that is thin on the upstream side and thick on the downstream side. In the compression unit 120C, the screw 130 is provided with such a tapered shaft 131, and the spiral pitch of the blade 132 is constant, so that the resin is compressed as the resin is pushed downstream. The pellet-shaped resin is uniformly heated by stably supplying the resin from the supply unit 120F to the compression unit at a constant supply rate, and performing compression and appropriate heating from the outside of the barrel 120 in the compression unit. Can be melted. As a result, it is possible to achieve extrusion of a resin in a good molten state with less air contamination and less contamination of unmelted gel and the like.

In the supply unit 120F and the measuring unit 120M, the shaft 131 has a constant thickness. The configuration including a shaft having such a constant thickness is a configuration intended to extrude at a constant flow velocity. For example, in the measuring unit 120M, since the thickness of the shaft 131 is constant and the spiral pitch of the blade 132 is constant, the resin can be extruded from the barrel discharge port 129 at a constant flow velocity.

[Characteristics of manufacturing method in extrusion process]
In the method for producing an optical film of the present invention, a barrel having a groove on the inner wall of the supply section is used as the barrel used in the extrusion process.
In addition, during the extrusion process, the temperature _TF of the inner wall of the barrel in the supply section is calculated by the following formula (1):
Tg + 90 ° C ≤ T _F ≤ Tg + 180 ° C ... (1)
Adjusted to meet. In formula (1), Tg is the glass transition temperature of the resin.
Furthermore, in the manufacturing method of the present invention, at a temperature T _F, and having a surface shape having no groove a barrel inner wall material in the feed section, the pellets, the dynamic friction coefficient mu _F is, it is 0.5 or less ..

In the supply section, in order to achieve appropriate compression and heating in the compression section, the resin pellets are required to be extruded downstream at a constant flow velocity and stably supplied to the compression section. When the temperature _TF satisfies the equation (1), it is possible to reduce undesired phenomena such as welding of the resin to the barrel and the screw in the supply section, and it is expected that smooth extrusion will be achieved thereby. To. However, in a new resin proposed in recent years as the material of the optical film, when molded into pellets, with T _F range satisfying the formula (1), such as a metal material constituting the inner wall of the barrel surface material The dynamic friction coefficient (corresponding to the dynamic friction coefficient μ _F ) with and may be a value such as 0.5 or less, which is much lower than that of the conventionally used resin. When extruding such pellets, the low coefficient of friction between the barrel inner wall and the pellets can make it difficult to extrude smoothly into the compression section. According to what the present inventor has found, in such a case, having a groove in the inner wall of the barrel in the barrel supply portion enables smooth extrusion.

With respect to the formula (1), the temperature _TF is (Tg + 90) ° C., preferably (Tg + 110) ° C. or higher, more preferably (Tg + 130) ° C. or higher, (Tg + 180) ° C. or lower, preferably (Tg + 175) ° C. or lower, and more. It is preferably (Tg + 170) ° C. or lower. When the temperature _TF is within the above preferable range, undesired phenomena such as welding of the resin to the barrel and the screw in the supply portion can be further satisfactorily reduced.

The time of the extrusion process, the temperature T _C of the inner wall of the barrel in the compression _section, and the temperature T _M of the inner wall of the barrel in the metering unit is not particularly limited, it can be appropriately adjusted to a temperature suitable for carrying out the extrusion process. Specifically, the temperature _{T C} of the inner wall of the barrel in the compression unit is preferably (Tg + 120) ℃ or higher, more preferably (Tg + 140) ℃ or higher, preferably (Tg + 210) ℃ or less, more preferably (Tg + 200) ℃ It is as follows. Temperature _{T M} of the inner wall of the barrel in the metering section is preferably (Tg + 120) ℃ or higher, more preferably (Tg + 140) ℃ or higher, preferably (Tg + 210) ℃ or less, more preferably (Tg + 200) ℃ or less.

The temperature of the inner wall of the barrel can be adjusted by heating from the outside of the barrel with a heating device. More specifically with reference to the example of FIG. 1, in each of the supply unit 120F, the compression unit 120C, and the measuring unit 120M of the barrel 120, an appropriate heating device (not shown) is arranged on the outside of the barrel. By heating the barrel thereby, the temperature of the inner wall of the barrel can be raised to a desired temperature. Further, a temperature measuring device such as a thermoelectric pair is provided on or near the surface of the inner wall of the barrel, the temperature of the inner wall of the barrel is monitored, and the output of the heating device is adjusted based on the monitored temperature to obtain the desired temperature of the inner wall of the barrel. Can be adjusted to a value.

The shape and orientation of the grooves in the inner wall of the supply section can be any orientation that allows smooth extrusion in the supply section. For example, the groove may be straight or curved. In the case of a linear groove, its orientation can be, for example, a direction parallel to the central axis of the barrel. When a linear groove in such a direction is adopted, pellets having a low friction coefficient can be smoothly extruded, pellets are less likely to be clogged in the groove, and a resin clogged inside the groove is used for barrel maintenance. Can be easily removed.

In the example of FIGS. 1 and 2, the barrel 120 has a groove 122 on the inner wall of the supply portion 120F. The groove 122 extends in a direction whose length is parallel to the central axis 130AX of the screw 130. As shown in FIG. 2, eight grooves 122 are provided so as to be uniform in the circumferential direction of the inner wall of the barrel 120. In this example, the length of the groove 122 is the length over the entire length of the supply unit 120F, but the present invention is not limited to this, and the length of the groove may be a length covering only a part of the supply unit, and the supply unit may be supplied. The length may be from the portion to the compression portion. From the viewpoint of exhibiting the effect of the groove, the length of the groove is preferably the length over the entire length of the supply portion. In the example of FIGS. 1 and 2, the cross-sectional shape of the groove is a rectangular shape having a width of 122 W and a depth of 122 D, but the present invention is not limited to this, and the cross-sectional shape of the groove is semicircular or U-shaped. It can have any shape. Each of the width 122W and the depth 122D of the groove 122 can be appropriately adjusted so that the pellet can be smoothly extruded. For example, it can be about 0.5 to 1.5 times the average value of the major axis of the pellet.

The material constituting the barrel is usually a metal such as stainless steel, and in particular, HCr stainless steel (stainless steel having a hard chrome plating treatment on the surface) is preferable from the viewpoint of pressure resistance and scratch resistance on the surface. .. Further, for observing the inside of the barrel, a part of the barrel may be a transparent material such as hard glass or quartz glass.

As for the internal dimensions of the barrel, dimensions suitable for the extrusion process can be appropriately selected. For example, when a screw having an inner diameter of 40 mm is used, the barrel length L may be 1,120 to 1,360 mm. The ratio of the barrel length L to the barrel diameter D, that is, L / D, can be 28 to 34.

In the production method of the present invention, the coefficient of dynamic friction μ _F is 0.50 or less, and can be a value such as 0.40 or less or 0.30 or less. Even if μ _F has such a small value, according to the present invention, smooth extrusion is possible, and therefore smooth optical film can be produced. The lower limit of the dynamic friction coefficient μ _F is not particularly limited, but may be, for example, 0.1 or more.

The dynamic friction coefficient μ _F is a dynamic friction coefficient at a temperature _TF , and is a dynamic friction coefficient between the barrel inner wall material in the supply portion having a surface shape having no groove and the pellets. The "barrel inner wall material in the supply section" is a material having the same properties as the barrel inner wall itself in the supply section or the barrel inner wall in the supply section in measuring the coefficient of dynamic friction with the pellets. For example, when most of the inner wall of the barrel is made of HCr stainless steel, a plate of HCr stainless steel can be used as the "barrel inner wall material in the supply section". Further, "a material for the inner wall of the barrel in the supply part having a surface shape having no groove" is a material for the inner wall of the barrel in the supply part, and the other material having no groove is the surface of the inner wall of the barrel in the supply part. It has the same surface roughness. The surface roughness can be defined by the arithmetic mean roughness. Since the arithmetic average roughness Ra of the surface of the inner wall of the barrel can be preferably 0.8 to 1.6 μm, the arithmetic average roughness of the “barrel inner wall material in the supply portion having a surface shape without grooves” The Ra can be equivalent to that. The surface roughness can be measured with a roughness measuring instrument (for example, Mitutoyo's small surface roughness measuring instrument Surftest SJ310).

The coefficient of kinetic friction μ _F can be measured in a measurement system using pellets used in carrying out the present invention and a barrel inner wall material having a surface shape having no groove in the supply section. A measurement system for the coefficient of dynamic friction μ _F will be described with reference to FIG. FIG. 3 is a vertical cross-sectional view schematically showing a measuring device having a coefficient of dynamic friction μ _F. In FIG. 3, the measuring device 300 includes a disk-shaped rotary table 310, a disk-shaped metal plate 320 placed on the upper surface of the rotary table 310, and a probe 330 installed on the upper side of the metal plate 320. The rotary table 310 includes a base 311 and a gripper 312 for gripping the metal plate 320, and the plurality of grippers 312 are pressed against the metal plate 320 in a state of being urged toward the central axis 310AX, whereby the metal is pressed. The plate 320 is fixed to the rotary table 310. The turntable 310 further comprises a shaft 313. When a rotational force is applied to the rotary table 310 via the shaft 313 by an appropriate rotary device (not shown), the rotary table rotates about the central axis 310AX. The measuring device 300 further includes a temperature adjusting device (not shown), whereby the temperature of the metal plate 320 is kept at a constant desired temperature. The metal plate 320 corresponds to a barrel inner wall material in the supply portion having a surface shape having no groove. The probe 330 includes a cylinder 331 containing the pellet 201 and a load transducer 332 installed inside the cylinder 331, which brings the pellet 201 into contact with the metal plate 320 at a constant pressure. Keeping the temperature of the metal plate 320 at the temperature _TF , rotating the rotary table 310 around the shaft 310AX, applying pressure to the pellet 201 with the transducer 332, measuring the pressure and the torque to the shaft 313, and measuring these. From the result, the dynamic friction coefficient μ _F can be obtained.

The screw used in the extrusion process may have voids inside its shaft at the supply section. In the production method of the present invention, an extrusion process, voids in the presence of a fluid, the surface temperature T _S of the screw shaft via a fluid, the following equation (2):
_{Tg-10 ℃ ≦ T S ≦} Tg + 60 ℃ ··· (2)
It is preferable to include adjusting to a range that satisfies.

In addition to the regulation of T _F mentioned above, when the regulation of T _S, independently of the temperature of the inner wall of the barrel in the supply unit, the temperature of the screw surface in the supply unit is also adjusted to a temperature suitable for extrusion of pellets This allows for smoother extrusion. The lower limit of T _S is preferably (Tg-10) ℃, more preferably be set to (Tg-5) ℃. The upper limit of T _S is preferably (Tg + 60) ℃, more preferably be set to (Tg + 55) ℃.

Examples of the fluid present in the voids in the shaft include heat medium oils and heat media such as water. When a substance having a low boiling point such as water is used as the fluid, it can be vaporized at a desired heating temperature at normal pressure. In that case, the fluid is used in a pressurized state or in a vapor state. Examples of the heat medium oil include silicone oil, a fluorine-based inert liquid, and a synthetic organic heat medium oil. Temperature T _S may be measured by suitable temperature measuring means. For example, it can be measured by bringing a thermocouple into contact with the surface of the shaft. More specifically, during operation of prior to the operation of the apparatus or device, contacting a thermocouple to the shaft surface through open window provided in the barrel, it can measure the temperature T _S.

In the example of FIGS. 1 and 2, the screw 130 has a gap 139 at a position corresponding to the supply unit 120F and at a position along the central axis 130AX. The gap 139 may be configured to open at the base of the screw 130 and communicate with a temperature control device (not shown) such as a heater from there. The fluid as a heat medium may be simply filled in the void 139, or may be circulated through the void 139 and the temperature controller. By adjusting the temperature of the fluid in the temperature regulating device, it is possible to adjust the temperature T _S to a desired temperature. The length of the gap 139 is the length over the entire length of the supply unit 120F, but the present invention is not limited to this, and the length of the gap may be a length covering only a part of the supply unit, from the supply unit to the compression unit. It may be over the length. From the viewpoint of expressing the effect of the void, the length of the void is preferably the length over the entire length of the supply portion.

[Process downstream from extrusion process]
The resin melted and extruded in the extrusion process is further passed through an appropriate device such as a die connected to the barrel discharge port to form a film-like shape, thereby achieving the production of an optical film by melt extrusion molding. be able to. By continuously supplying the resin, the optical film can be continuously produced by melt extrusion molding, and as a result, a long film can be obtained as the optical film. The "long" film means a film having, for example, 5 times or more the width of the film, preferably 10 times or more, and specifically in a roll shape. A film that has a length that allows it to be wound up and stored or transported. The upper limit of the ratio of the length to the width of the film is not particularly limited, but may be, for example, 100,000 times or less.

In the production method of the present invention, since the extrusion process has the above-mentioned specific characteristics, smooth extrusion can be performed even for resin pellets having a small friction coefficient, and a good optical film can be efficiently produced. be able to. Specifically, when a resin having good properties such as high heat resistance and bending resistance, but having a small dynamic friction coefficient μ _F , which makes it difficult to stably transport the resin in the supply section, is used as the material. Even so, it is possible to smoothly extrude the resin from the supply section to the compression section, and to achieve good extrusion of the resin in a molten state with less mixing of air and less mixing of unmelted gel and the like. .. By supplying the molten resin to the die by such smooth extrusion and performing molding, it is possible to efficiently produce a good optical film.

[Pellet-like resin]
In the production method of the present invention, a pellet-shaped resin is used as the material of the optical film. A "pellet-like" resin is a granular resin that is solid in the feeding process. The specific shape of the pellet is generally a substantially cylindrical shape obtained by cutting the strand, but the present invention is not limited to this, and pellets having any shape can be used. For example, it can be various shapes such as a spherical shape, an elliptical spherical shape, a rectangular parallelepiped, and a mixture thereof. Further, for example, crushed products generated when the resin is formed into these shapes may be included in the category of pellets.

The size of the pellet can be appropriately adjusted to a size suitable for the production method of the present invention. From the viewpoint of obtaining appropriate fluidity and ease of handling, the size of the pellet is preferably 2 mm to 5 mm on average in terms of the number of major axes thereof.

The resin having a pellet-like shape used in the present invention may contain a polymer and an optional component which may be contained if necessary. Examples of the polymer constituting the resin include a polymer selected from the group consisting of an alicyclic structure-containing polymer, a cellulosic polymer, a polyethylene terephthalate polymer, an acrylic polymer, and a mixture thereof. Be done.

Examples of the alicyclic structure-containing polymer include an alicyclic structure-containing polymer having crystallinity and a non-crystalline alicyclic structure-containing polymer. Among these, a crystalline alicyclic structure-containing polymer can be preferably used in the production method of the present invention. That is, the alicyclic structure-containing polymer having crystallinity has good properties such as high heat resistance and bending resistance, while the resin pellets containing such a polymer have friction with other materials such as metal. The coefficient may be very low compared to conventionally used resins. When such pellets are adopted, it is difficult to carry out the extrusion process in the conventional method for producing an optical film, but by applying the production method of the present invention, even pellets of such a resin can be easily carried out. The extrusion process can be carried out. Therefore, by applying the pellets of the resin containing the crystalline alicyclic structure-containing polymer to the production method of the present invention as a material, while enjoying the preferable properties of the crystalline alicyclic structure-containing polymer. Moreover, it is possible to efficiently produce a good optical film.

Here, the crystalline polymer means a polymer having a melting point Mp. Further, the polymer having a melting point Mp means a polymer whose melting point Mp can be observed with a differential scanning calorimeter (DSC).

Examples of the alicyclic structure-containing polymer having crystallinity include the following polymers (α) to (δ). Among these, the polymer (β) is preferable as the alicyclic structure-containing polymer having crystallinity because an optical film having excellent heat resistance can be easily obtained.
Polymer (α): A ring-opening polymer of a cyclic olefin monomer having crystallinity.
Polymer (β): A hydride of the polymer (α) having crystallinity.
Polymer (γ): An addition polymer of a cyclic olefin monomer having crystallinity.
Polymer (δ): A hydride of the polymer (γ) or the like, which has crystallinity.

Specifically, the alicyclic structure-containing polymer having crystallinity includes a ring-opening polymer of dicyclopentadiene having crystallinity and a hydride of the ring-opening polymer of dicyclopentadiene. It is more preferable that it has crystallinity, and it is particularly preferable that it is a hydride of a ring-opening polymer of dicyclopentadiene and has crystallinity. Here, in the ring-opening polymer of dicyclopentadiene, the ratio of the structural unit derived from dicyclopentadiene to all the structural units is usually 50% by weight or more, preferably 70% by weight or more, more preferably 90% by weight or more. More preferably, it refers to a polymer of 100% by weight.

The hydride of the ring-opening polymer of dicyclopentadiene preferably has a high proportion of racemo-diad. Specifically, the proportion of the repeating unit racemo-diad in the hydride of the ring-opening polymer of dicyclopentadiene is preferably 51% or more, more preferably 70% or more, and particularly preferably 85% or more. A high proportion of racemo diads indicates a high syndiotactic stereoregularity. Therefore, the higher the proportion of racemo diad, the higher the melting point of the hydride of the ring-opening polymer of dicyclopentadiene tends to be.
The proportion of racemo diads can be determined based on the ¹³ C-NMR spectral analysis described in Examples below.

The crystalline alicyclic structure-containing polymer does not have to be crystallized before the optical film is produced. However, after the optical film is produced, the crystalline alicyclic structure-containing polymer contained in the optical film can usually have a high crystallinity because it is crystallized. Based on this, advantageous effects such as heat resistance can be obtained. The specific range of crystallinity can be appropriately selected according to the desired performance, but is preferably 10% or more, more preferably 15% or more. Crystallinity can be measured by X-ray diffraction.

The alicyclic structure-containing polymer having crystallinity as described above can be produced, for example, by the method described in International Publication No. 2016/067893.

The weight average molecular weight (Mw) of the crystalline alicyclic structure-containing polymer is preferably 10,000 or more, more preferably 15,000 or more, particularly preferably 20,000 or more, and preferably 100,000 or more. Below, it is more preferably 80,000 or less, and particularly preferably 50,000 or less. A polymer having such a weight average molecular weight is excellent in a balance between mechanical strength, molding processability and heat resistance.

The melting point Mp of the crystalline alicyclic structure-containing polymer is preferably 200 ° C. or higher, more preferably 230 ° C. or higher, and preferably 290 ° C. or lower. By using a crystalline polymer having such a melting point Mp, an optical film having a better balance between moldability and heat resistance can be obtained.

The glass transition temperature Tg of the crystalline alicyclic structure-containing polymer is preferably 80 ° C. or higher, more preferably 85 ° C. or higher, further preferably 90 ° C. or higher, preferably 250 ° C. or lower, more preferably 170 ° C. or higher. It is below ° C. A polymer having a glass transition temperature in such a range is less likely to be deformed and stressed when used at a high temperature, and has excellent heat resistance.

The molecular weight distribution (Mw / Mn) of the alicyclic structure-containing polymer having crystallinity is preferably 1.2 or more, more preferably 1.5 or more, particularly preferably 1.8 or more, and preferably 3. It is 5 or less, more preferably 3.4 or less, and particularly preferably 3.3 or less. When the molecular weight distribution is at least the lower limit of the above range, the productivity of the polymer can be increased and the production cost can be suppressed. Further, when it is not more than the upper limit value, the amount of the low molecular weight component becomes small, so that the relaxation at the time of high temperature exposure can be suppressed and the stability of the optical film can be improved.

The weight average molecular weight Mw and the number average molecular weight Mn of the polymer are poly by gel permeation chromatography (hereinafter abbreviated as "GPC") using cyclohexane (toluene when the resin is not dissolved) as a solvent. It can be measured in terms of isoprene (when the solvent is toluene, it is converted to polystyrene). Alternatively, the weight average molecular weight Mw and the number average molecular weight Mn of the polymer can be measured by GPC using tetrahydrofuran as a solvent in terms of polystyrene.

The ratio of the alicyclic structure-containing polymer having crystallinity in the resin constituting the pellet can be adjusted to a desired ratio from the viewpoint of obtaining an optical film having particularly excellent heat resistance and bending resistance. Such a ratio is preferably 80% by weight to 100% by weight, more preferably 90% by weight to 100% by weight, still more preferably 95% by weight to 100% by weight, and particularly preferably 98% by weight to 100% by weight.

Examples of cellulosic polymers include triacetyl cellulose (Tg (glass transition temperature): 160 to 180 ° C.). Examples of polyethylene terephthalate-based polymers include polyethylene terephthalate (Tg: 70 ° C., Tc: 250 to 255 ° C.). Examples of the acrylic polymer include polymethylmethacrylate (Tg: 90 ° C.) and ethyl polymethacrylate (Tg: 100 ° C.).

The resin constituting the pellet may contain an arbitrary component in combination with the above-mentioned polymer. Examples of arbitrary components include inorganic fine particles; stabilizers such as antioxidants, heat stabilizers, ultraviolet absorbers, and near-infrared absorbers; resin modifiers such as lubricants and plasticizers; colorants such as dyes and pigments. ; And antistatic agents. As these arbitrary components, one type may be used alone, or two or more types may be used in combination at an arbitrary ratio. However, from the viewpoint of remarkably exerting the effect of the present invention, it is preferable that the content ratio of any component is small. For example, the total ratio of any components is preferably 20 parts by weight or less, more preferably 15 parts by weight or less, further preferably 10 parts by weight or less, and particularly preferably 5 parts by weight or less, based on 100 parts by weight of the polymer. preferable. Further, since the amount of any component contained in the resin is small, bleed-out of any component can be suppressed.

[Optical film]
The optical film obtained by the manufacturing method of the present invention can be usefully used as a member constituting various optical devices such as a liquid crystal display device, a display device such as an organic electroluminescence display device, a display device with a touch panel, and a solar cell. ..

Hereinafter, the present invention will be specifically described with reference to Examples. However, the present invention is not limited to the examples shown below, and can be arbitrarily modified and implemented without departing from the scope of claims of the present invention and the equivalent scope thereof.
In the following description, "%" and "part" representing the amount are based on weight unless otherwise specified. In addition, the operations described below were performed under normal temperature and pressure conditions unless otherwise specified.

〔Evaluation method〕
(Measurement method of molecular weight)
The weight average molecular weight and number average molecular weight of the polymer were measured at 38 ° C. (ring-opening polymer of dicyclopentadiene and its hydride) as a standard polystyrene equivalent value by gel permeation chromatography using tetrahydrofuran as an eluent. .. As a measuring device, HLC8320GPC manufactured by Tosoh Corporation was used.

(Measurement of glass transition temperature and melting point)
Using a differential operating calorimeter (DSC), the temperature was raised at 10 ° C./min to determine the glass transition temperature Tg and melting point Mp of the sample, respectively.

(Measuring method of the ratio of racemo diad of polymer)
Using orthodichlorobenzene-d ⁴ / trichlorobenzene-d ³ (mixing ratio (weight basis) 1/2) as a solvent, apply the inverse-gated decoupling method at 200 ° C. to perform ¹³ C-NMR measurement of the polymer. went. In the results of this ¹³ C-NMR measurement, the signal of 43.35 ppm derived from meso-diad and the signal of 43.43 ppm derived from racemo-diad were used with the peak of 127.5 ppm of orthodichlorobenzene-d ⁴ as a reference shift. Was identified. Based on the intensity ratios of these signals, the proportion of racemo diads in the polymer was determined.

(Measuring method of hydrogenation rate of polymer)
The hydrogenation rate of the polymer, o-dichlorobenzene -d ₄ as a solvent, at 145 ° ^C., as measured by 1 H-NMR measurement.

(Surface roughness)
The surface roughness was measured with a roughness measuring instrument (Mitutoyo's small surface roughness measuring instrument Surftest SJ310).

[Production Example 1: Production of a resin containing a crystalline alicyclic structure-containing polymer]
The metal pressure resistant reactor was sufficiently dried and then replaced with nitrogen. 154.5 parts of cyclohexane, 42.8 parts of a 70% cyclohexane solution (30 parts of dicyclopentadiene), and 1-hexene containing dicyclopentadiene (endo content of 99% or more) were added to this pressure-resistant reactor. 1.9 parts were added and heated to 53 ° C.

0.014 parts of the tetrachlorotungsten phenylimide (tetrahydrofuran) complex was dissolved in 0.70 parts of toluene to prepare a solution. To this solution was added 0.061 part of a diethylaluminum ethoxide / n-hexane solution having a concentration of 19% and stirred for 10 minutes to prepare a catalytic solution.
This catalyst solution was added to a pressure resistant reactor to initiate a ring-opening polymerization reaction. Then, the reaction was carried out for 4 hours while maintaining 53 ° C. to obtain a solution of a ring-opening polymer of dicyclopentadiene.
The number average molecular weight (Mn) and weight average molecular weight (Mw) of the obtained ring-opening polymer of dicyclopentadiene are 8,750 and 28,100, respectively, and the molecular weight distribution (Mw / Mn) obtained from these is Was 3.21.

To 200 parts of the obtained solution of the ring-opening polymer of dicyclopentadiene, 0.037 parts of 1,2-ethanediol was added as a terminator, heated to 60 ° C., and stirred for 1 hour to stop the polymerization reaction. I let you. A part of a hydrotalcite-like compound (“Kyoward (registered trademark) 2000” manufactured by Kyowa Chemical Industry Co., Ltd.) was added thereto, and the mixture was heated to 60 ° C. and stirred for 1 hour. After that, 0.4 part of a filtration aid ("Radiolite (registered trademark) # 1500" manufactured by Showa Chemical Industry Co., Ltd.) was added, and a PP pleated cartridge filter ("TCP-HX" manufactured by ADVANTEC Toyo Co., Ltd.) was used as an adsorbent. The solution was filtered off.

To 200 parts of a solution of a ring-opening polymer of dicyclopentadiene after filtration (30 parts of polymer amount), 100 parts of cyclohexane is added, 0.0043 parts of chlorohydride carbonyltris (triphenylphosphine) ruthenium is added, and hydrogen is added. The hydrogenation reaction was carried out at a pressure of 6 MPa and 180 ° C. for 4 hours. As a result, a reaction solution containing a hydride of a ring-opening polymer of dicyclopentadiene was obtained. In this reaction solution, hydrides were precipitated to form a slurry solution.

The hydride contained in the reaction solution and the solution were separated using a centrifuge and dried under reduced pressure at 60 ° C. for 24 hours to obtain a hydride of a crystallinity ring-opening polymer of dicyclopentadiene 28. I got 5 copies. The hydrogenation rate of this hydride was 99% or more, the glass transition temperature Tg was 93 ° C., the melting point Mp was 262 ° C., and the ratio of racemo diad was 89%. The weight average molecular weight of the hydride was in the range of 27,000 to 32,000.

Antioxidant (tetrakis [methylene-3- (3', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane was added to 100 parts of the hydride of the obtained ring-opening polymer of dicyclopentadiene. After mixing 1.1 parts of "Irganox (registered trademark) 1010" manufactured by BASF Japan, a twin-screw extruder ("TEM-37B" manufactured by Toshiba Machine Co., Ltd.) equipped with four die holes having an inner diameter of 3 mmΦ. I put it in. A resin (a1) containing a crystalline alicyclic structure-containing polymer is formed into a strand-shaped molded product by hot melt extrusion molding using a twin-screw extruder and then shredded with a strand cutter. Pellets were obtained. This resin (a1) is a resin containing a hydride of a ring-opening polymer of dicyclopentadiene as a crystalline alicyclic structure-containing polymer.

The operating conditions of the twin-screw extruder were as follows.
-Barrel set temperature = 270 ° C to 280 ° C.
-Die set temperature = 250 ° C.
-Screw rotation speed = 145 rpm.
-Feeder rotation speed = 50 rpm.

[Example 1]
The pellet of the resin (a1) obtained in Production Example 1 was supplied to a melt extrusion molding machine. The melt extruder was provided with an extruder 100 schematically shown in FIGS. 1 and 2 and a T-die connected downstream thereof.

As the extruder 100, a uniaxial visualization extruder (manufactured by Plastic Engineering Laboratory, barrel inner diameter D = 40 mm, barrel inner length L = 1200 mm (that is, L / D = 30)) was used.

In the barrel 120 of the extruder, the supply section 120F, the compression section 120C, and the weighing section 120M are defined by the thickness of the shaft 131 of the screw 130, and these lengths are 400 mm, 400 mm, and 400 mm, respectively. It was.

As the barrel 120 of the extruder 100, one having a groove 122 on the inner wall of the supply unit 120F was used. Eight grooves 122 are provided so that the length direction thereof extends parallel to the central axis 130AX of the screw 130 and is uniform in the circumferential direction of the inner wall of the barrel 120 as shown in FIG. The length of the groove 122 was the length over the entire length of the supply unit 120F, the width 122W of the groove 122 was 1 mm, and the depth 122D was 0.5 mm. The inner wall of the barrel 120 was partly an observation window made of hard glass (Pyrex (registered trademark)) for observing the inside of the barrel, and most of the other part (area of 80% or more) was HCr stainless steel. .. The arithmetic mean roughness Ra of the inner wall of the barrel 120 other than the groove 122 and the observation window portion was 1.2 μm.

Pellets 201 were put into the hopper 110 of the extruder 100. An extrusion step was carried out in which the pellet 201 was extruded from the upstream side to the downstream side of the barrel 120 by rotating the screw 130 at 30 rpm. The pellet 201 is formed by adjusting the heat medium oil (synthetic organic heat medium oil, manufactured by Matsumura Petroleum Co., Ltd., trade name "Barreltherm 300") filled in the voids 139 in the barrel 120 and the screw 130 to a constant temperature. It was heated and melted. Temperature, 230 ° C. The inner wall of the barrel temperature _{T F} in the supply unit 120F, 270 ° C. The inner wall of the barrel temperature _{T C} in the compression section 120C, and the inner wall of the barrel temperature _{T M} in the metering section 120M and 285 ° C.. To adjust the temperature of the inner wall of the barrel in each part, the barrel is heated by a heating device provided on the outside of the barrel, the temperature of the inner wall of the barrel is monitored by a thermocouple provided near the surface of the inner wall of the barrel, and the temperature of the heating device is adjusted based on the monitored temperature. This was done by adjusting the output. Further, the temperature of the thermal oil in the gap 139 is adjusted to 120 ° C., thereby was 112 ° C. The surface temperature _{T S} of the shaft 131 in the supply unit 120F. Surface temperature T _S of the shaft 131, prior to the operation of the extruder was measured by contact thermocouple shaft 131 surface through open window provided on barrel 120. The molten resin was discharged from the barrel discharge port 129. An optical film was continuously produced by supplying the discharged resin to a die and extruding it from the die into a film shape.

In the extrusion step, the state of extrusion was observed and evaluated from the following viewpoints. The evaluation results are shown in Table 2.
(A) Presence or absence of resin welding in the supply unit 120F (B) Presence or absence of extruder stop due to screw overload (torque over 60 Nm) (C) Presence or absence of unmelted gel in the resin discharged from the barrel discharge port 129 (D) Extrusion amount (kg / hr)
(E) Comprehensive evaluation of extrusion status: If all of (A) to (C) are "none", it is evaluated as "good". Other than that, it is evaluated as "bad".

Further, the dynamic friction coefficient μ _F was measured using the measuring device schematically shown in FIG. In FIG. 3, the measuring device 300 includes a disk-shaped rotary table 310, a disk-shaped metal plate 320 placed on the upper surface of the rotary table 310, and a probe 330 installed on the upper side of the metal plate 320. The plurality of grippers 312 were pressed against the metal plate 320 in a state of being urged toward the central axis 310AX, whereby the metal plate 320 was fixed to the rotary table 310. As the metal plate 320, a material having the same material as the inner wall of the barrel 120 used in the extrusion step was selected with respect to the development of the coefficient of friction with respect to the pellet 201. That is, as the rotary table 320, a rotary table 320 having a hard chrome plating treatment on the upper surface thereof was used. The arithmetic average roughness Ra of the upper surface of the rotary table 320 was 1.2 μm, and the Vickers hardness was about 1,100 Hv. A temperature regulator (not shown) was used to keep the temperature of the metal plate 320 at _TF (ie, 230 ° C. in Example 1). A layer-sized pellet 201 was placed in the cylinder 331, a transducer 332 was set on the pellet 201, and a pressure of 2N was applied to the interface between the layer of the pellet 201 and the upper surface of the metal plate 320. In this state, the rotary table 310 was rotated at a peripheral speed of 0.03 cm / s. In this state, the coefficient of dynamic friction μ _F was measured by measuring the torque to the shaft portion 342.

[Examples 2 and 3, Comparative Example 1 and Comparative Example 4]
Except for the following changes, the optical film was manufactured and evaluated and the friction coefficient was measured by the same operation as in Example 1. The results are shown in Table 2.
Barrel inner wall temperature T _F in the supply unit _120F, and the screw shaft surface temperature T _S at the temperature and supply of thermal oil in the gap 139, were changed as shown in Table 1. The temperature of the rotary table 320 when measuring the friction coefficient was set to the same temperature as the barrel inner wall temperature _TF in the supply unit 120F.

[Comparative Example 2]
Except for the following changes, the optical film was manufactured and evaluated and the friction coefficient was measured by the same operation as in Example 1. The results are shown in Table 2.
Barrel inner wall temperature T _F in the supply unit _120F, and the screw shaft surface temperature T _S at the temperature and supply of thermal oil in the gap 139, were changed as shown in Table 1. The temperature of the rotary table 320 when measuring the friction coefficient was set to the same temperature as the barrel inner wall temperature _TF in the supply unit 120F.
A barrel 120 having no groove 122 on its inner wall was used.

[Comparative Example 3]
Except for the following changes, the optical film was manufactured and evaluated and the friction coefficient was measured by the same operation as in Example 1. The results are shown in Table 2.
-The barrel inner wall temperature _TF in the supply unit 120F was changed as shown in Table 1. The temperature of the rotary table 320 when measuring the friction coefficient was set to the same temperature as the barrel inner wall temperature _TF in the supply unit 120F.
-The temperature of the heat transfer medium oil in the void 139 was not adjusted.
A barrel 120 having no groove 122 on its inner wall was used.

１）ペレットが溶融してしまい、測定ができなかった。
２）一定の押出量での押出ができなかったので、押出量の測定ができなかった。

1) The pellet melted and measurement was not possible.
2) Since it was not possible to extrude at a constant extrusion amount, the extrusion amount could not be measured.

As is clear from the results of Examples and Comparative Examples, even when extrusion is performed when the coefficient of friction between the barrel inner wall and the pellet is as low as 0.5 or less, the temperature of the barrel inner wall in the supply section is adjusted to a specific range, thereby adjusting the barrel. By measuring the temperature of the pellet in contact with the inner wall in a specific range and using a barrel with a groove in the inner wall, the rotation of the screw is well transmitted to the pellet as a force for extrusion, and good extrusion is performed. Can be achieved.

100: Extruder 110: Hopper 111: Upper opening 112: Lower opening 120: Barrel 120C: Compressing part 120F: Supply part 120M: Measuring part 121: Resin inlet 122: Groove 122D: Depth 122W: Width 129: Discharge port 130 : Screw 130AX: Central shaft 131: Shaft 132: Blade 139: Void 201: Pellet 300: Measuring device 310: Rotating table 310AX: Central shaft 311: Base 312: Grip 313: Shaft 320: Metal plate 330: Probe 331: Cylindrical 332: Load transducer

Claims (5)

A method for producing an optical film, comprising a supply step of supplying a pellet-shaped resin to a single-screw extruder and an extrusion step of extruding the supplied resin by the extruder.
The extruder includes a barrel and a screw provided within the barrel, the extrusion step comprising pushing the resin from the upstream side to the downstream side of the barrel by rotating the screw.
The barrel includes a supply part, a compression part, and a measuring part in this order from the upstream.
The barrel has a groove in its inner wall at the supply section.
The temperature _TF of the inner wall of the barrel in the supply unit is the following formula (1):
Tg + 90 ° C ≤ T _F ≤ Tg + 180 ° C ... (1)
However, Tg is the glass transition temperature of the resin.
Wherein the temperature T _F, and having a surface shape not having grooves a barrel inner wall material in the supply unit, with the pellet, the dynamic friction coefficient mu _F is 0.50 or less, the production method. The manufacturing method according to claim 1, wherein the arithmetic mean roughness of the inner wall of the barrel in the supply section other than the groove is 0.5 μm or more and 10 μm or less. The screw has an air gap in the interior of the shaft in the feed section, the extrusion process, the presence of fluid in the gap, through the fluid, the surface temperature T _S of the shaft in the feed unit, The following formula (2):
_{Tg-10 ℃ ≦ T S ≦} Tg + 60 ℃ ··· (2)
The production method according to claim 1 or 2, which comprises adjusting the amount to satisfy the above conditions. The manufacturing method according to any one of claims 1 to 3, wherein the groove extends in a direction parallel to the axial direction of the extruder. The resin according to claim 1 to 4, wherein the resin contains a polymer selected from the group consisting of an alicyclic structure-containing polymer, a cellulosic polymer, a polyethylene terephthalate polymer, an acrylic polymer, and a mixture thereof. The production method according to any one of the following items.

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