JP6851847B2 - Polymer filter, polymer film manufacturing method and polymer film - Google Patents

Description

The present invention relates to a polymer filter, a method for producing a polymer film, and a polymer film.

When the polymer is melted and extruded, a polymer filter that filters the polymer is used for the purpose of removing foreign substances. As an example of the polymer filter, there is one described in Japanese Patent Application Laid-Open No. 2008-18598 (Patent Document 1).

This polymer filter has a leaf disc type filter that filters the polymer, a center pole that supports the leaf disc type filter, and a holding disc that is attached to the center pole and holds down the leaf disc type filter. Then, a polymer flow path is provided which communicates from the holding disk to the internal flow path of the center pole. A filter member different from the leaf disc type filter is provided in the polymer flow path.

As a result, the polymer can flow into the internal flow path of the center pole via the polymer flow path, and the retention of the polymer in the internal flow path of the center pole is reduced. As a result, the thermal deterioration of the polymer due to the retention of the polymer is reduced, and the deterioration of the quality of the extruded product using the polymer is prevented.

Japanese Unexamined Patent Publication No. 2008-18598

However, in the conventional polymer filter, since a filter member is separately provided in the polymer flow path, the cost is high. Further, the position where the polymer stays in the polymer filter is not limited to the position examined in Patent Document 1, and a technique for further reducing the occurrence of polymer retention is desired.

Therefore, an object of the present invention is to provide a polymer filter capable of further reducing the retention of the polymer and reducing the thermal deterioration of the polymer without providing a separate filter member.
Another object of the present invention is to provide a method for producing a polymer film, which can reduce thermal deterioration of the polymer and can produce a high-quality polymer film.
Another object of the present invention is to provide a high quality polymer film in which thermal deterioration of the polymer is reduced.

In order to solve the above problems, the polymer filter of the present invention is used.
A container body with a polymer inlet and opening,
The lid attached to the opening of the container body and
A plurality of disk-shaped filter elements arranged in the container body, filtering the polymer flowing into the container body from the polymer inlet portion and discharging the polymer from the inner peripheral hole portion,
An internal flow path in which one end is fixed to the lid portion, inserted into the inner peripheral hole portion of the filter element to support the plurality of filter elements in a laminated state, and the polymer flowing in from the inner peripheral hole portion is discharged to the outside of the container body. With a center pole,
It is provided with a holding portion that is attached to the other end of the center pole and holds the plurality of filter elements together with the lid portion.
In the size of the end space between the holding portion and the endmost filter element closest to the holding part, the inner peripheral side of the endmost filter element is smaller than the outer peripheral side of the endmost filter element. ..

According to the polymer filter of the present invention, in the size of the end space between the pressing portion and the endmost filter element closest to the pressing portion, the inner peripheral side of the endmost filter element is the endmost filter element. Since it is smaller than the outer peripheral side, the dead space on the inner peripheral side of the outermost space can be reduced, and the retention of the polymer on the inner peripheral side of the outermost space can be reduced. At the same time, by reducing the retention of the polymer on the inner peripheral side of the outermost space, the retention of the polymer in the internal flow path of the center pole can be reduced.

Therefore, even if a separate filter member is not provided, the retention of the polymer can be further reduced to reduce the thermal deterioration of the polymer, and as a result, the quality of the extruded product using the polymer can be improved.

Further, in one embodiment of the polymer filter, the end face of the holding portion facing the end filter element is attached to the axis of the center pole so that the inner peripheral side of the end face approaches the end filter element. It is tilted with respect to the planes that are orthogonal to each other.

According to the above embodiment, the end face of the holding portion facing the endmost filter element is inclined with respect to a plane orthogonal to the axis of the center pole so that the inner peripheral side of the end face approaches the endmost filter element. ing. As a result, the size of the inner peripheral side of the outermost space can be made smaller than the size of the outer peripheral side of the outermost space with a simple configuration.

Also, in one embodiment of the polymer filter,
The terminalmost filter element has a first end surface facing the holding portion and a second end surface opposite to the first end surface.
The inner peripheral side of the second end surface has a pedestal portion, while the inner peripheral side of the first end surface is a flat surface without the pedestal portion.

According to the above embodiment, the terminalmost filter element has a first end surface facing the pressing portion, and the inner peripheral side of the first end surface is a flat surface without a base portion. As a result, the size of the inner peripheral side of the outermost space can be reduced with a simple configuration.

Also, in one embodiment of the polymer filter,
Gaskets are provided on the inner peripheral side between the adjacent filter elements and on the inner peripheral side between the holding portion and the endmost filter element.
The thickness of the gasket between the holding portion and the endmost filter element is thinner than the thickness of the other gaskets.

According to the above embodiment, the thickness of the gasket between the pressing portion and the endmost filter element is thinner than the thickness of the other gaskets. As a result, the size of the inner peripheral side of the outermost space can be reduced with a simple configuration.

Further, in one embodiment of the method for producing a polymer film, the molten polymer is filtered using the polymer filter, and then the filtered polymer is formed into a film to produce a polymer film.

According to the above embodiment, since the polymer film is produced by using the polymer filter, the thermal deterioration of the polymer can be reduced and a high quality polymer film can be produced.

Further, in one embodiment of the polymer film, the number of gel defects is 0.8 pieces / m ² or less.

Here, the gel defect means a gel-like fine grain generated by thermal deterioration of the polymer, and becomes a defect as a product.

According to the above embodiment, the number of gel defects is 0.8 pieces / m ² or less, so that a high-quality polymer film in which thermal deterioration of the polymer is reduced can be obtained.

Further, in one embodiment of the polymer film, the dimension in the width direction is 1000 mm or more.

According to the above embodiment, the dimension in the width direction is 1000 mm or more, so that even a large polymer film can be of good quality.

Further, in one embodiment of the polymer film, the number of gel defects in the central region in the width direction is 0.5 times or more and 2.0 times or less with respect to the number of gel defects in the other regions in the width direction.

Here, the central region in the width direction is a region including the center in the width direction, which is 20% of the total width.

According to the above embodiment, the number of gel defects in the central region in the width direction is 0.5 times or more and 2.0 times or less with respect to the number of gel defects in the other regions in the width direction. The number of gel defects in the film is reduced, resulting in a high-quality polymer film.

According to the polymer filter of the present invention, in the size of the end space between the pressing portion and the endmost filter element closest to the pressing portion, the inner peripheral side of the endmost filter element is the endmost filter element. Since it is smaller than the outer peripheral side, the retention of the polymer can be further reduced and the thermal deterioration of the polymer can be reduced without providing a separate filter member.
According to the method for producing a polymer film of the present invention, since the polymer film is produced using the polymer filter, the thermal deterioration of the polymer can be reduced and a high quality polymer film can be produced.
According to the polymer film of the present invention, the number of gel defects is 0.8 pieces / m ² or less, so that a high-quality polymer film in which thermal deterioration of the polymer is reduced can be obtained.

It is sectional drawing which shows one Embodiment of the polymer filter of this invention. It is an enlarged sectional view of a polymer filter. It is an enlarged sectional view of the holding part side of a polymer filter. It is an image figure which shows the Example of a polymer film. It is an image figure which shows the comparative example of a polymer film. It is sectional drawing which shows the Example of the polymer filter. It is sectional drawing which shows the comparative example of a polymer filter.

Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

(Polymer filter)
FIG. 1 is a cross-sectional view showing an embodiment of the polymer filter of the present invention. FIG. 2 is an enlarged cross-sectional view of the polymer filter. As shown in FIGS. 1 and 2, the polymer filter 1 has a container body 11, a lid portion 12, a plurality of disc-shaped filter elements 20, a center pole 30, and a pressing portion 40.

The polymer filter 1 is connected between the extruder and the mold, filters the polymer melted and extruded by the extruder, and sends it out to the mold. The polymer sent out from the mold is formed into a film to obtain an optical film. The polymer is a heat-degrading resin such as polypropylene or polycarbonate. The polymer flows in the polymer filter 1 in the direction indicated by the dotted arrow in the figure.

The container body 11 has a polymer inlet portion 11a and an opening portion 11b. The polymer inlet 11a and opening 11b are located on opposite sides of each other. The lid portion 12 is attached to the opening portion 11b of the container body 11. The lid portion 12 has a through hole 12a. The lid portion 12 is attached to the container body 11, and a storage space 11c is formed in the container body 11. The container body 11 is provided with a heating device such as a heater to heat the polymer in the container body 11.

The plurality of filter elements 20 are arranged in the storage space 11c of the container body 11. The filter element 20 is a leaf disc type filter. The filter element 20 has an inner peripheral hole portion 20a in the center. The filter element 20 filters the polymer that has flowed into the container body 11 from the polymer inlet portion 11a and discharges it from the inner peripheral hole portion 20a.

The filter element 20 includes two disc-shaped filtration units 21 that are superposed on each other, a support portion 22 that is located between the two filtration units 21 and supports the filtration unit 21, and two filtration units 21. It has an inner peripheral fixing portion 23 for fixing the inner peripheral edge of the filter, and an outer peripheral fixing portion 24 for fixing the outer peripheral edge of the two filtration portions 21. The filtration unit 21 is made of, for example, a sintered body. The support portion 22 is made of, for example, a wire mesh. The inner peripheral fixing portion 23 and the outer peripheral fixing portion 24 are made of, for example, an annular metal fitting. The inner peripheral hole portion of the inner peripheral fixing portion 23 constitutes the inner peripheral hole portion 20a of the filter element 20. The inner peripheral fixing portion 23 has a through hole 23a that communicates the space between the two filtration portions 21 and the external space. The polymer is filtered by passing through the filtration section 21, passes through the space between the two filtration sections 21, and is discharged from the through hole 23a.

The center pole 30 is inserted into the container body 11. One end of the center pole 30 is inserted into the through hole 12a of the lid portion 12 and fixed to the lid portion 12 with a bolt or the like. The center pole 30 is inserted into the inner peripheral hole portion 20a of the filter element 20 and supports the plurality of filter elements 20 in a laminated state. The center pole 30 has an internal flow path 30a that discharges the polymer that has flowed in from the inner peripheral hole portion 20a to the outside of the container body 11.

The center pole 30 is a tubular member having an opening at one end. The internal space of the tubular member constitutes the inner diameter flow path 30a. The opening at one end of the tubular member faces the outside of the container body 11, and the opening at the other end of the tubular member is located inside the container body 11.

A plurality of concave grooves 30b extending along the axis L of the center pole 30 are provided on the peripheral surface of the center pole 30. The plurality of concave grooves 30b are arranged in the circumferential direction about the axis L. The bottom surface of the concave groove 30b has a plurality of through holes 30c communicating with the internal flow path 30a. The concave groove 30b faces the inner surface of the inner peripheral hole portion 20a of the filter element 20. That is, the concave groove 30b communicates with the through hole 23a of the inner peripheral fixing portion 23. The polymer filtered by the filter element 20 flows into the recessed groove 30b from the through hole 23a of the inner peripheral fixing portion 23, then flows into the inner peripheral hole portion 20a through the through hole 30c, and is discharged to the outside of the container body 11. To.

The pressing portion 40 is attached to the other end (sealing side) of the center pole 30 and holds a plurality of filter elements 20 together with the lid portion 12. The pressing portion 40 has a central hole portion 40a, and the other end portion (sealing side) of the center pole 30 is inserted into the central hole portion 40a of the pressing portion 40. A bolt 50 is screwed into the other end of the center pole 30, and by tightening the bolt 50, a plurality of filter elements 20 are pressed via the pressing portion 40.

In FIG. 1, the center pole 30 is represented by a tubular member having openings at one end, but a tubular member having openings at both ends may also be used. In that case, one end of the tubular member is inserted into the central hole portion 40a of the pressing portion 40 and screwed by the bolt 50 to press the plurality of filter elements 20 via the pressing portion 40. At this time, the opening at the other end is closed by the bolt 50.

FIG. 3 is an enlarged cross-sectional view of the polymer filter 1 on the holding portion 40 side. As shown in FIGS. 2 and 3, the gasket 60 is provided on the inner peripheral side between the adjacent filter elements 20 and on the inner peripheral side between the pressing portion 40 and the filter element 20. The gasket 60 has a function of contacting the inner peripheral fixing portion 23 of the filter 20 and sealing the contact portion.

In the adjacent filter elements 20, between the base portion 23b provided on the inner peripheral fixing portion 23 of one filter element 20 and the base portion 23b provided on the inner peripheral fixing portion 23 of the other filter element 20. The gasket 60 is sandwiched. The base portion 23b projects in the direction along the axis L and is formed in an annular shape centered on the axis L. As a result, spaces S1 and S2 that serve as flow paths for the polymer are formed between the adjacent filter elements 20 and between the pressing portion 40 and the filter element 20.

In the size of the adjacent space S1 between the adjacent filter elements 20, the inner peripheral side of the filter element 20 and the outer peripheral side of the filter element 20 have the same size. On the other hand, in the size of the end space S2 between the holding portion 40 and the endmost filter element 20 closest to the holding part 40 (hereinafter, referred to as the endmost filter element 20A), the inside of the endmost filter element 20A. The peripheral side is smaller than the outer peripheral side of the outermost filter element 20A. The most extreme space S2 is smaller than the adjacent space S1.

Specifically, the end face 41 of the holding portion 40 facing the endmost filter element 20A is oriented with respect to a plane orthogonal to the axis L of the center pole 30 so that the inner peripheral side of the end face 41 approaches the filter element 20A. Is tilted. That is, the end surface 41 of the pressing portion 40 is a tapered surface. As a result, the size of the inner peripheral side of the outermost space S2 can be made smaller than the size of the outer peripheral side of the outermost space S2 with a simple configuration. The inclination angle of the end face 41 may be increased so that the inner peripheral side of the end face 41 approaches the filter element 20A, and the size of the inner peripheral side of the outermost space S2 can be made smaller.

The endmost filter element 20A has a first end surface 201 facing the pressing portion 40 and a second end surface 202 opposite to the first end surface 201. The first and second end faces 201 and 202 are parallel to a plane orthogonal to the axis L of the center pole 30. The inner peripheral side of the second end surface 202 has the base portion 23b, while the inner peripheral side of the first end surface 201 is a flat surface without the base portion 23b. As a result, the size of the innermost space S2 on the inner peripheral side can be reduced with a simple configuration. Both end faces of the other filter elements 20 other than the endmost filter element 20A are parallel to a plane orthogonal to the axis L and have a base portion 23b.

The thickness of the gasket 60 between the pressing portion 40 and the outermost filter element 20A is thinner than the thickness of the other gaskets 60 between the adjacent filter elements 20. As a result, the size of the innermost space S2 on the inner peripheral side can be reduced with a simple configuration.

The operation of the polymer filter 1 will be described.

The polymer is allowed to flow in from the polymer inlet portion 11a of the container body 11. After that, the polymer passes through the polymer flow path between the pressing portion 40 and the container body 11, and moves to the outer peripheral side of the filter element 20. After that, the polymer passes through the adjacent space S1 and the endmost space S2 and flows into the inside of the filter element 20. The polymer filtered by the filter element 20 passes through the through hole 30c of the center pole 30 and is guided to the internal flow path 30a. The polymer is then drained into the exterior space of the polymer filter 1.

According to the polymer filter 1, in the size of the end space S2 between the pressing portion 40 and the end filter element 20A, the inner peripheral side of the end filter element 20A is the outer circumference of the end filter element 20A. Since it is smaller than the side, the dead space on the inner peripheral side of the outermost space S2 can be reduced to reduce the retention of the polymer on the inner peripheral side of the outermost space S2.

At the same time, by reducing the retention of the polymer on the inner peripheral side of the outermost space S2, the retention of the polymer in the internal flow path 30a of the center pole 30 can be reduced. It is considered that this can increase the flow velocity of the polymer on the inner peripheral side of the outermost space S2, and accordingly, the flow velocity of the polymer in the internal flow path 30a of the center pole 30 can also be increased.

Therefore, the retention of the polymer can be further reduced to reduce the thermal deterioration of the polymer due to the retention of the polymer, and as a result, the quality of the extruded product using the polymer can be improved. For example, it is possible to reduce the occurrence of streaks on the film as an extruded product. Further, it is not necessary to separately provide a conventional filter member different from the disk-shaped filter element, and the cost can be reduced.

In short, as a result of diligently examining the retention position in the polymer filter 1, the inventor of the present application has found that in addition to the internal flow path 30a of the center pole 30, polymer tends to retain on the inner peripheral side of the end space S2. Furthermore, it has been found that the retention of the internal flow path 30a of the center pole 30 can also be reduced by reducing the retention of the innermost space S2 on the inner peripheral side. In this way, by simply reducing the size of the inner peripheral side of the outermost space S2, the retention of the inner peripheral side of the outermost space S2 and the internal flow path 30a of the center pole 30 can be reduced, and the thermal deterioration of the polymer is dramatically improved. Can be reduced.
Incidentally, the retention of the polymer in each place in the polymer filter can be evaluated by calculating the average residence time with, for example, analysis software Polyflow (manufactured by ANSYS).

(Manufacturing method of polymer film)
Next, a method for producing a polymer film will be described. In this production method, the molten polymer is filtered using the polymer filter 1, and then the filtered polymer is formed into a film to produce a polymer film.

Specifically, the polymer filter 1 is connected between the extruder and the mold. In the extruder, the polymer is heated to melt and extrude. The polymer extruded by the extruder is guided to the polymer filter 1. The polymer filtered by the polymer filter 1 is guided to a mold. It is extruded from a mold to form a film of polymer. The formed film is brought into contact with a roller to be cooled. The cooled film is wound up to obtain a roll-shaped raw film. The raw film is a long polymer film.

Therefore, in the method for producing a polymer film, since the polymer film is produced by using the polymer filter 1, the thermal deterioration of the polymer can be reduced and a high quality polymer film can be produced. For example, on the surface of the polymer film, the number of gel defects due to thermal deterioration of the polymer described later is reduced, and the occurrence of streaks is reduced.

(Polymer film)
Next, the polymer film will be described. FIG. 4A uses a copolymer resin of methyl methacrylate-methyl acrylate (manufactured by Sumipex MH Sumitomo Chemical Co., Ltd.) as a raw material, and uses a polymer filter shown in FIG. 5A described later based on the method for producing a polymer film. It is an image figure of the polymer film manufactured by an example. That is, FIG. 4A shows the polymer film 10 produced by the polymer filter 1. M indicates the dimension in the flow direction, and W indicates the dimension in the width direction.

As shown in FIG. 4A, the surface of the polymer film 10 has gel defects. Gel defects refer to fine gel-like particles generated by thermal deterioration of a polymer, and become defects as a product. Gel defects are indicated by dots in the figure. The number of gel defects in the polymer film 10 of the present embodiment is 0.8 pieces / m ² or less, preferably 0.5 pieces / m ² or less. The number of gel defects is usually 0.05 / m ² or more. As a result, a high-quality polymer film 10 in which thermal deterioration of the polymer is reduced can be obtained.

The widthwise dimension W of the polymer film 10 is preferably 1000 mm or more. As a result, the quality of the large polymer film 10 can be improved. In FIG. 4A, M is 4000 m and W is 1340 mm.

The number of gel defects was detected by using an in-line detector using a CCD camera, the number of pixels of the camera was 5000 pixels, the detection resolution was 100 μm, and the light source was a metal halide lamp 180 W.

The polymer film 10 is made of, for example, an acrylic resin. The acrylic resin is a (meth) acrylic resin and means a polymer of an acrylic acid ester or a methacrylic acid ester. As the methacrylic acid ester polymer, for example, a polymer mainly composed of alkyl methacrylate is preferable because it has excellent transparency and high rigidity. The monomer composition of alkyl methacrylate is preferably 70% by weight or more, more preferably 80% by weight or more, still more preferably 90% by weight or more, based on 100% by weight of the total of all the monomers. And the alkyl methacrylate is 99% by weight or less. The acrylic resin may be a homopolymer of alkyl methacrylate, or a copolymer of 50% by weight or more of alkyl methacrylate and 50% by weight or less of a monomer other than alkyl methacrylate. May be good. As the alkyl methacrylate, those having an alkyl group having 1 to 4 carbon atoms are usually used, and methyl methacrylate is particularly preferably used. Further, the monomer other than alkyl methacrylate may be a monofunctional monomer having one polymerizable carbon-carbon double bond in the molecule, or two or more polymerizable carbons in the molecule. -It may be a polyfunctional monomer having a carbon double bond. In particular, monofunctional monomers are preferably used, and examples thereof include alkyl acrylates such as methyl acrylate and ethyl acrylate, styrene-based monomers such as styrene and alkylstyrene, and acrylonitrile and methacrylonitrile. Such as unsaturated nitriles. When alkyl acrylate is used as the copolymerization component, the number of carbon atoms thereof is usually 1 to 8.

The number of gel defects in the central region Z1 in the width direction of the polymer film 10 is 0.5 times or more and 2.0 times or less with respect to the number of gel defects in the other regions Z2 in the width direction of the polymer film 10. It is preferably 0.7 times or more and 1.5 times or less, more preferably 0.8 times or more and 1.3 times or less, and further preferably 1.0 times or more and 1.3 times or less. The central region Z1 is a region including the center in the width direction, which is 20% of the total width. As a result, the number of gel defects in the central region Z1 is reduced, and the polymer film 10 of good quality is obtained.

FIG. 4B is an image diagram of the polymer film 100 of the comparative example. The polymer film 100 of the comparative example is manufactured by a polymer filter different from the polymer filter 1 of the present invention (comparative example using the polymer filter FIG. 5B described later). In this polymer filter, the configuration of the end space S2 is different from that of the polymer filter 1 shown in FIG. 3, and the size of the inner peripheral side of the end space S2 is the same as the size of the outer circumference side of the end space S2. It becomes.

In FIG. 4B, like FIG. 4A, M is 4000 m and W is 1340 mm. As shown in FIG. 4B, the polymer film 100 of the comparative example has a larger number of gel defects than the polymer film 10 of FIG. 4A. During film formation, the heat-deteriorated polymer content retained in the polymer filter usually tends to collect in the center of the film in the width direction, so the number of gel defects in the central region Z1 and the number of gel defects in the other regions Z2. The ratio to is increasing.

The number of gel defects between the polymer film 10 (FIG. 4A) of this example and the polymer film 100 (FIG. 4B) of the comparative example is shown in Table 1 below. In Table 1, the values actually measured in FIGS. 4A and 4B.

As shown in Table 1, in the examples, the overall average of the number of gel defects was reduced as compared with the comparative example, and further, the number ratio of the number of gel defects in the central region to the number of gel defects in the other regions. Is decreasing.

The present invention is not limited to the above-described embodiment, and the design can be changed without departing from the gist of the present invention.

In the above embodiment, the end surface of the pressing portion on the filter element side is a tapered surface, but the end surface of the pressing portion is a plane orthogonal to the axis of the center pole, and the first end surface of the endmost filter element on the pressing portion side is formed. The tapered surface may be such that the inner peripheral side of the outermost space is smaller than the outer peripheral side. Further, the end face of the pressing portion and the first end face of the filter element at the end may be tapered so that the inner peripheral side of the outermost space is smaller than the outer peripheral side.

In the above embodiment, the end surface of the pressing portion on the filter element side is a tapered surface, but a concave curved surface or a convex curved surface may be used.

In the above-described embodiment, the base portion is not provided on the first end surface of the endmost filter element on the holding portion side, but the base portion is provided on the first and second end faces of the endmost filter element, and the base portion of the first end surface is provided. The height of the portion may be lower than the height of the base portion of the second end surface.

In the above embodiment, the tubular center pole 30 has been shown, but the present invention is not limited to this. The center pole 30 may have a rod shape, extend along the shaft L, and may be provided with a plurality of concave grooves extending to the outside of the container body 11. The polymer filtered by the filter element 20 may flow into the groove and then be discharged to the outside of the container body 11.

FIG. 5A shows an embodiment of the above embodiment, and FIG. 5B shows a comparative example.

The polymer filter shown in FIG. 5A has the same configuration as that of the above embodiment, and the size of the inner peripheral side of the outermost space S2 is smaller than the size of the outer peripheral side of the outermost space S2. The filter element 20 is shown by hatching for the sake of clarity.

As a raw material for the polymer film, a copolymer resin of methyl methacrylate-methyl acrylate (manufactured by Sumipex MH Sumitomo Chemical Co., Ltd.) is used as a raw material, and a filter element with a filtration accuracy of 5 μm or less is used, and the temperature of the polymer filter is 240 ° C. or higher and 300 ° C. Hereinafter, the procedure was carried out under the condition that the molten polymer viscosity was about 500 Pa · s.
Then, the obtained melt was extruded and narrow pressure molding between rolls to obtain a polymer film.
The average residence time of the polymer in the polymer filter was calculated using the analysis software Polyflow (manufactured by ANSYS) with a shear rate of about 1.3 / s in the polymer filter.

The average residence time of the polymer in the most extreme space S2 and the average residence time of the polymer at the X and Y points in the adjacent space S1 were determined. The X point is the adjacent space S1 between the fifth filter element 20 and the sixth filter element 20 counting from the holding portion 40 side, and the Y point is the tenth filter element 20 counting from the holding portion 40 side. Adjacent space S1 between and the eleventh filter element 20.

In the outermost space S2, when the gap t1 on the inner peripheral side was 1.5 mm and the gap t2 on the outer peripheral side was 3 mm, the average residence time was 390 seconds. The average residence time at the X point of the adjacent space S1 was 98 seconds, and the average residence time at the Y point of the adjacent space S1 was 96 seconds. In the adjacent space S1, the gap on the inner peripheral side and the gap on the outer peripheral side are 3 mm. On the other hand, in the outermost space S2, when the gap t1 on the inner peripheral side is 1 mm and the gap t2 on the outer peripheral side is 3 mm, the average residence time is 311 seconds.

The polymer filter shown in FIG. 5B has a different configuration of the end space S2 from the polymer filter shown in FIG. 5A, and the size of the inner peripheral side of the end space S2 is the size of the outer circumference side of the end space S2. Is the same as. That is, the size of the end space S2 is the same as that of the adjacent space S1. The configuration is the same as that of FIG. 5A except for the configuration of the outermost space S2. Other conditions such as the polymer raw material were carried out in the same manner as in the above-mentioned Examples.

Then, the average residence time of the polymer at the X and Y points (see FIG. 5A) of the endmost space S2 and the adjacent space S1 was determined. In the outermost space S2, when the gap t1 on the inner peripheral side was 3 mm and the gap t2 on the outer peripheral side was 3 mm, the average residence time was 640 seconds. The average residence time at the X point of the adjacent space S1 was 98 seconds, and the average residence time at the Y point of the adjacent space S1 was 96 seconds.

As a result, the average residence time of the end space S2 of this example (FIG. 5A) was reduced to about half of the average residence time of the end space S2 of the comparative example (FIG. 5B). In other words, in this embodiment, the average residence time of the most extreme space S2 is 5 times or less the average residence time of the adjacent space S1. Further, in this embodiment, the smaller the gap t1 on the inner peripheral side of the outermost space S2, the smaller the average residence time. From this, it can be seen that the retention of the polymer in the end space S2 can be reduced by making the inner peripheral side of the end space S2 smaller than the outer circumference side.

1 Polymer filter 10 Polymer film 11 Container body 11a Polymer inlet 11b Opening 12 Lid 20 Filter element 20A Endmost filter element 20a Inner peripheral hole 201 1st end surface 202 2nd end surface 21 Filtration part 22 Support part 23 Inner circumference fixing part 23b Base 24 Peripheral fixing part 30 Center pole 30a Internal flow path 40 Holding part 41 End face 50 Bolt 60 Gasket L Center pole axis S1 Space between adjacent filter elements (adjacent space)
S2 Space between the holding part and the filter element (endmost space)
M Flow direction dimensions W Width direction dimensions Z1 Central area Z2 Other areas

Claims (2)

A container body with a polymer inlet and opening,
The lid attached to the opening of the container body and
A plurality of disk-shaped filter elements arranged in the container body, filtering the polymer flowing into the container body from the polymer inlet portion and discharging the polymer from the inner peripheral hole portion,
An internal flow path in which one end is fixed to the lid portion, inserted into the inner peripheral hole portion of the filter element to support the plurality of filter elements in a laminated state, and the polymer flowing in from the inner peripheral hole portion is discharged to the outside of the container body. With a center pole,
It is provided with a holding portion that is attached to the other end of the center pole and holds the plurality of filter elements together with the lid portion.
In the size of the end space between the holding portion and the endmost filter element closest to the holding part, the inner peripheral side of the endmost filter element is smaller than the outer peripheral side of the endmost filter element. ,
A polymer filter having at least one configuration selected from the following (A) to (C).
(A) The end face of the holding portion facing the end filter element is inclined with respect to a plane orthogonal to the axis of the center pole so that the inner peripheral side of the end face approaches the end filter element. (B) The terminalmost filter element has a first end surface facing the holding portion and a second end surface opposite to the first end surface.
The inner peripheral side of the second end surface has a pedestal, while the inner peripheral side of the first end surface is a flat surface without the pedestal. (C) The inner peripheral side between adjacent filter elements. A gasket is provided on the inner peripheral side between the holding portion and the endmost filter element.
The thickness of the gasket between the holding portion and the endmost filter element is thinner than the thickness of the other gaskets. A method for producing a polymer film, wherein the molten polymer is filtered using the polymer filter according to claim 1, and then the filtered polymer is formed into a film to produce a polymer film.

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