JP2002283344A - Molten polymer filtering device and filtering method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a molten polymer filtering device for controlling the contained residual gas, gelatinous substance and cracked gas which can be causes for defects in resin moldings as well as a filtering method using this filtering device. SOLUTION: This molten polymer filtering device is characterized in that the residual gas in an internal polymer flow path of a casing is eliminated and the abnormal residence of the polymer into a blocked region is prevented from occurring. Also the filtering method using this device is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for filtering a molten polymer. It relates to a filtration method.

[0002]

2. Description of the Related Art As a filter for filtering a molten polymer, a cylindrical filter or a leaf disk filter is generally used. In general, the latter is used by stacking a plurality of leaf disk filters through a support made of a tubular body, and is more expensive than the former, but has a pressure resistance and is suitable for filtration or microfiltration of a high-viscosity molten polymer, and Since a large filtration area can be secured for the volume, the time required for the molten polymer to pass through the filtration step can be shortened, and it is often used because it is suitable for filtering the molten polymer which is susceptible to thermal deterioration. I have.

FIG. 7A shows an example of a filtering apparatus using a leaf disk. The molten polymer is supplied to the inlet 36 of the filtration device 40.
Then, it is introduced into the casing 37, branched into each leaf disk filter 23, filtered, and moved to the polymer channel 39 in the support 38. In such a conventional filtration device, after the molten polymer flows into the filtration device, it is basically a polymer flow structure in which the molten polymer flows in and out, so that gas is likely to remain in the polymer flow path in the casing. This is because the gas tends to move upward, whereas the molten polymer does not flow upward, leaving only the gas.

[0004] After the molten polymer flows into the filtration device, the residual gas is mixed into the molten polymer little by little in the form of bubbles or the like and flows out, resulting in a defect in the resin molded article. When the resin molded body is a resin sheet or a film, the resin sheet or the film may be broken.

FIG. 7B shows an enlarged view of the column head of FIG. 7A. Here, the molten polymer filtered by the leaf disk filter 23 moves to the flow path 44 between the inner wall of the leaf disk filter and the outer wall of the column, and is guided into the column through a hole 45 provided on the circumference of the column 38.

However, a part of the molten polymer that has moved to the flow path 44, contrary to this flow, flows through the gap 46 between the outer wall of the column and the inner wall of the end plate, which is a fitting structure, and flows into the closed region of the column head. The flowed molten polymer 47 stays abnormally, and often leads to defects or breakage due to the outflow of gel-like substances and decomposition gases. In the figure, 23 is a leaf disk filter, 39 is a polymer channel in a support, 41 is a fastening bolt, 42 is a tip plate, and 43 is a seal ring.

Even if a seal ring is provided between the outer wall of the column and the inner wall of the end plate to prevent the above flow, a closed area filled with gas remains in the polymer flow path. Can not.

The outflow of the gas frequently occurs particularly immediately after the molten polymer has flowed into the filtration device. Therefore, the flow of the gas is stopped after the flow of the molten polymer is stopped after the flow of the molten polymer flows into the manufacturing apparatus for the resin molded article. It may take a long time before the production of the molded body can be started.

Further, even after the production of the resin molded article is started,
The gas that still remains may also flow out irregularly, for example several times a day, resulting in product losses. Above all, in the case of manufacturing resin sheets and films, since the product is produced in units of a certain length or more, once the bubbles flow out and the resin sheet or film breaks, the resin sheet manufactured for several hours before that And film may not be a product. Furthermore, if the film is wound around the cooling drum or longitudinal stretching roll due to sudden breakage, the amount of polymer discharged will be reduced, so the pressure of the polymer that has abnormally stayed in the closed area will increase from the surrounding area, causing gelled polymer and decomposition The gas can flow back and out, leading to repeated bursts, which can be very damaging.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art and to eliminate the residual gas in the polymer flow path in the casing and the abnormal accumulation of the polymer in the closed area. An object of the present invention is to provide a molten polymer filtration device and a filtration method capable of suppressing the occurrence and breakage of defects of a resin molded product and improving the production efficiency.

[0011]

According to a first aspect of the present invention, there is provided a molten polymer filtration apparatus for stacking a plurality of leaf disk filters in a casing by passing the same through a support having a polymer flow path. In the molten polymer filtration device for filtering the molten polymer introduced into the column by passing through the leaf disk filter, the polymer flow path of the column is constituted by a counter-flow type structure, and first, the molten polymer introduced into the column tube is a column tip plate. The flow is reversed into a fountain shape between the casing and the casing, fed into the leaf disc filter from the casing inner wall, and then passed through the flow path between the leaf disc filter inner wall and the column outer wall, and then the circumference is formed at the ring-shaped junction. A molten polymer filtration device having a flow channel structure flowing out from one upper position.

Further, in the molten polymer filtering apparatus of the present invention, the column and the end plate form an integral structure instead of a fitting structure, and the molten polymer is gradually introduced to the complete seal portion or the outside on the opposite side in the longitudinal direction. It is preferable to use a molten polymer filtration device characterized by having a structure having a non-stagnation portion that flows out.

Moreover, the molten polymer filtering device of the present invention has a structure in which a conical portion is provided on the casing side facing the outlet of the support end plate to realize a radial flow without stagnation. Characterized molten polymer filtration devices are preferred.

Further, in the apparatus for filtering a molten polymer according to the present invention, the terminal of the outer wall groove of the column is located below the upper surface of the ring-shaped junction, and the upper surface of the ring-shaped junction and the upper surface of the outflow pipe coincide with each other. In addition, the outflow pipe has a divergent structure in the cross section in the direction opposite to the flow from the outlet, and has a structure that realizes a flow on a circumference without stagnation. preferable.

Further, in the method for filtering a molten polymer according to the present invention, which achieves the above-mentioned object, a plurality of leaf disk filters are stacked and housed in a casing through a column having a polymer flow path, and the molten disk introduced into the casing is introduced. In a method for filtering a molten polymer, in which the polymer is passed through the leaf disk filter and filtered, the polymer flow path of the column is constituted by a countercurrent type structure, and first, the molten polymer introduced into the column is moved between the column tip plate and the casing. The flow is reversed into a fountain shape, fed into the leaf disk filter from the inner wall of the casing, and then passed through the flow path between the inner wall of the leaf disk filter and the outer wall of the support column. This is a method for filtering a molten polymer, characterized by a flow channel structure flowing out of the polymer.

In particular, in the method for filtering a molten polymer according to the present invention, the casing is disposed vertically with the support column end plate facing downward, and the molten polymer in the casing can be lowered and raised. Is preferred.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an apparatus for producing a resin molded article provided with an apparatus for filtering a molten polymer according to one embodiment of the present invention. According to this manufacturing apparatus, a resin molded body such as a resin sheet or a film can be manufactured.

The apparatus 18 for manufacturing a resin molded product includes a hopper 1, an extruder 2,
Short pipe 3, gear pump 4, short pipe 5, filtration device 6, short pipe 7,
Cap 8, cooling drum 9, peeling roll 10, thickness gauge 12, longitudinal stretching machine 13, horizontal stretching machine tenter 14, thickness gauge 1
5, the take-up roll 16 is arranged.

The information 17 of the thickness gauge 15 is sent to the base 8. In this case, one extruder is used. However, in the case of a device for producing a multilayer film having two or more layers, a similar configuration having two or more extruders and a feed block for joining a plurality of molten polymer streams is used. There may be.

In FIG. 1, a polymer such as polyethylene terephthalate is supplied from a hopper 1 to an extruder 2, heated and kneaded by the extruder 2, melted and extruded into a short tube 3. Next, the molten resin is measured by a gear pump 4 provided for improving the accuracy of the discharge amount, is extruded quantitatively, and passes through a short pipe 5 to reach a filtration device 6. The molten polymer from which foreign matters and degraded substances (oxidative decomposition and thermal decomposition) have been removed by the filtration device 6 is extruded through a short pipe 7 from a base 8 to a cooling drum 9 in a sheet shape.

Here, in order to prevent thermal decomposition of the molten polymer after passing through the filtration device 6, it is preferable to minimize the residence time before being extruded from the die, and it is often arranged directly above the die. . The die may be any type such as a T type, a coat hanger type and a fish tail type. Further, it may be either a single-layer die or a multilayer die. The cooling drum 9 is rotated in the direction of arrow a while the surface thereof is controlled to about room temperature. The molten polymer extruded into a sheet shape on the cooling drum 9 adheres onto the cooling drum 9 and then solidifies. To form a sheet.

Next, the solidified sheet 11 is peeled off from the cooling drum 9 by a peeling roll 10,
After the thickness in the width direction is monitored by the thickness gauge 12, the longitudinal stretching machine 1
After being stretched in the longitudinal direction at 3 and stretched in the transverse direction by the transverse stretching machine tenter 14, the thickness is measured in the width direction by the thickness gauge 15 and wound up by the winding roll 16.

The slit gap at a corresponding position in the die slit width direction is controlled by the adjusting mechanism based on the thickness data 17 in the sheet width direction obtained by the thickness gauges 12 and 15.

Next, an apparatus for filtering a molten polymer according to an embodiment of the present invention will be described in detail with reference to FIG.

In FIG. 2, FIG. 2A is a schematic longitudinal sectional view showing an example of the apparatus for filtering a molten polymer of the present invention. In the structure shown in FIG.
After the flow is reversed from a casing inner wall 20 which is first introduced into a support pipe 20 having a counter-flow type structure and is provided with a tip plate 21 of the support and a conical portion 27 through a casing 22, each leaf is introduced from the inner wall of the casing. Disk filter 23
After passing through the flow path 24 between the inner wall of the leaf disk filter and the outer wall of the support column, it flows out from one location on the circumference at the ring-shaped junction 25. In FIG. 2, FIG. 2B is a schematic cross-sectional view schematically showing the cross-sectional structure of the merging-outflow portion b of the molten polymer filtration device of the present invention shown in FIG. 2A.

The molten polymer at the junction has a structure in which it is completely sealed by the seal ring 26 with the outside or forms a minute gap, and has a non-stagnation portion that gradually flows to the outside. In addition, the end of the column outer wall groove is located below the upper surface of the ring-shaped junction, and the upper surface of the ring-shaped junction and the upper surface of the outflow pipe are formed in a structure.

Here, the gas before the molten polymer flows in is first pushed out of the column tube into the casing together with the flow of the molten polymer, and then flows into the leaf disc filter from the inner wall of the casing along the flow of lowering and uppering. Then, after passing through the flow path between the inner wall of the leaf disk filter and the outer wall of the column, the molten polymer and the gas flow out efficiently from one place on the circumference at the ring-shaped junction. In a series of these processes, the polymer channel is filled with the molten polymer, and no gas remains.

Here, the leaf disk filter and the column will be described in more detail with reference to FIG.

FIG. 3 shows a portion c in FIG. 2A.
The molten polymer is filtered by a filter medium 29 composed of a metal powder sintered body, a metal fiber non-woven sintered body, a ceramic powder body, or a combination thereof, and passes through the polymer flow path 30 on the secondary side of the filter. It passes through a supporting member 31 made of a metal mesh or the like and passes through a hole 33 provided in a hub ring 32 through which a post is passed in the center, and is led to a flow path 24 between the inner wall of the leaf disc filter and the outer wall of the post. FIG. 4 shows a dd cross section of the column shown in FIG. 2C.

Here, the hub ring 3 is provided on the outer wall of the support 20.
2 has a circumferential projection 35 provided for forming the polymer flow path 24. In addition, as the shape of the column, a pillar having a polygonal shape such as a hexagon as shown in FIG. 5 or a shape mainly formed by an arc as shown in FIG. 6 may be used. Here, it is necessary to select an appropriate shape for the width and depth of the groove in consideration of the pressure loss and residence time of the entire filtration device. In addition, it is preferable to give a deeper gradient toward the downstream side so that the flow rate of the polymer passing through each leaf disk filter becomes uniform.

In the above embodiment, the longitudinal direction of the column is vertical. However, the longitudinal direction of the column may be horizontal or oblique, and is limited to the vertical direction. is not.

Examples of the polymer in the present invention include thermoplastic resins represented by polyolefins such as polypropylene and polyethylene, polyesters such as polyethylene terephthalate and polyethylene naphthalate, and the like.
Heat-resistant resins such as meta-aramid and para-aramid can be used. If necessary, additives such as a weathering material, a lubricant, an antistatic agent, and a pigment may be added to these resins.

[0033]

EXAMPLE 120 120 leaf disk filters made by sintering and compressing stainless steel fibers and having a filtration accuracy of 5 μm and an outer diameter of 222 mm were stacked on a support of the filtration device shown in FIG. 2 and housed in a casing.

Then, polyethylene terephthalate was melted at about 295 ° C., passed through the above-mentioned filtration device, and extruded from a die into a sheet. At this time, the gas in the polymer flow path of the column was pushed out of the base with the inflow of the molten polymer, and the production of the product sheet could be started within 2 hours after the molten polymer flowed into the filtration device. Further, after the start of the production, the sheet was not broken by the outflow of the bubbles, the gelling polymer, and the decomposition gas for 14 days until the filtration device was replaced in order to switch the kind of the sheet, and the productivity was remarkably improved.

On the other hand, 120 leaf disk filters each having a filtration accuracy of 5 μm and an outer diameter of 222 mm, which are formed by sintering and compressing stainless steel fibers in the same manner as described above, are stacked on the support having the conventional structure shown in FIG. The polyethylene terephthalate was melted at about 295 ° C., passed through the filtration device, and extruded from a die into a sheet.

At this time, it took 5 hours or more before the production of the sheet was started after the bubbles disappeared from the die. In addition, gas still remained in the filtration device, and air bubbles flowed out once or twice on average two days after the start of production, and the sheet was broken each time.

Further, when the film is wound around the cooling drum or the longitudinal stretching roll due to sudden breakage, the discharge amount of the polymer is reduced. Therefore, the pressure of the polymer which has abnormally stayed in the closed region becomes higher than the peripheral portion, and the gel is formed. The polymer and cracked gas flowed backward and flowed out, and when restarted, tears broke out.

[0038]

According to the present invention, since the polymer flow path of the column has a counter-current type structure and the molten polymer in the casing can be moved in and out, the gas in the casing is removed by the molten polymer flowing into the filtration device. It can be efficiently pushed out of the filtering device.

Further, since the column and the end plate are formed not in a fitting structure but in an integral structure and do not have a closed region in the polymer flow path, the following effects are obtained. (1) The production of a resin molded body can be started in a short time after the molten polymer flows into the filtration device, and the production efficiency is improved. (2) There is no outflow of residual gas even after the start of production of the resin molded body, and stable production can be continued and the yield is improved. (3) After a sudden break occurs, there is no outflow of gelled polymer or decomposition gas that has abnormally stayed in the closed region and the production efficiency at the time of restart is improved.

[Brief description of the drawings]

FIG. 1 shows an apparatus for producing a resin molded article provided with an apparatus for filtering a molten polymer according to an embodiment of the present invention.

FIG. 2 shows a molten polymer filtration device according to an embodiment of the present invention, and FIG. 2A is a schematic longitudinal sectional view showing an example of the molten polymer filtration device of the present invention; FIG. 2B is a schematic cross-sectional view schematically showing the cross-sectional structure of the merging-outflow part b of the molten polymer filtration device of the present invention shown in FIG. 2A.

FIG. 3 is a schematic cross-sectional view schematically showing a portion c in the apparatus for filtering a molten polymer of the present invention shown in FIG. 2A.

FIG. 4 shows an example of a sectional view taken along line dd of the apparatus for filtering a molten polymer of the present invention shown in FIG. 3;

FIG. 5 shows another example of the dd cross-sectional view of the molten polymer filtration device of the present invention shown in FIG. 3;

FIG. 6 shows another example of the dd cross-sectional view of the molten polymer filtration device of the present invention shown in FIG.

7 shows an example of a filtering device using a leaf disk. FIG. 7A is a schematic longitudinal sectional model diagram showing an example of the filtering device, and FIG. 7B is a diagram shown in FIG. 7A. 3 shows a portion e in the filtration device.

[Brief description of reference numerals]

1: Hopper 2: Extruder 3: Short pipe 4: Gear pump 5: Short pipe 6: Filtration device 7: Short pipe 8: Cap 9: Cooling drum 10: Peeling roll 11: Sheet 12: Thickness gauge 13: Vertical stretching Machine 14: Lateral stretching machine 15: Thickness gauge 16: Winding roll 17: Thickness information 18: Manufacturing device for resin molded body 19: Inlet of filtration device 20: Countercurrent type support 21: Tip plate 22: Casing 23: Leaf Disc filter 24: Polymer channel between the inner wall of the leaf disk filter and the outer wall of the support 25: Ring-shaped confluent part 26: Seal ring 27: Conical part of the casing 28: New filtering device 29: Filter medium 30: Secondary side of the filter Polymer flow path 31: Support body 32: Hub ring 33: Hole 34: Packing 35: Projection of column outer wall 36: Inlet of filtration device 37: Casing 38: Column 39: Polymer flow path in the column 40: Conventional filtration device 41: Tightening bolt 42: Tip plate 43: Seal ring 44: Polymer channel between the leaf disk filter inner wall and the column outer wall 45: Hole 46: Column outer wall and the end plate Gap between inner walls 47: Molten polymer flowing into closed area

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) C08L 101: 00 B01D 29/34 501E 520A 35/02 L

Claims (6)

[Claims] An apparatus for filtering a molten polymer, wherein a plurality of leaf disk filters are stacked and housed in a casing through a column having a polymer flow path, and the molten polymer introduced into the casing is filtered through the leaf disk filter. In the above, the polymer flow path of the column is constituted by a countercurrent type structure, and first, the molten polymer introduced into the column pipe reverses the flow between the column tip plate and the casing in a fountain shape, and enters the leaf disk filter from the casing inner wall. The molten polymer is characterized by having a flow channel structure which has a flow channel structure which is fed in and then flows out from one place on the circumference at a ring-shaped junction after passing through the flow channel between the inner wall of the leaf disk filter and the outer wall of the support post. Filtration device. 2. The apparatus for filtering a molten polymer according to claim 1, wherein the post and the end plate form an integral structure instead of a fitting structure, and the opposite side in the longitudinal direction gradually transfers the molten polymer to a complete seal portion or the outside. An apparatus for filtering a molten polymer, comprising a structure having a non-stagnation portion to flow out. 3. The molten polymer filtration device according to claim 1, wherein the filter has a structure in which a conical portion is provided on the casing side facing the outlet of the support plate end plate. Filtration device. 4. The apparatus for filtering a molten polymer according to claim 1, wherein the end of the outer wall of the support post is located below the upper surface of the ring-shaped junction, and the upper surface of the ring-shaped junction and the upper surface of the outflow pipe. A filtration device for a molten polymer, characterized in that the filtration device is constituted by a structure having the same structure. 5. A molten polymer filtering apparatus for stacking and storing a plurality of leaf disk filters in a casing through a support having a polymer flow path, and filtering the molten polymer introduced into the casing through the leaf disk filter. In the filtration method using the above, the polymer flow path of the column is constituted by a counter-current type structure, and the molten polymer introduced into the column first reverses the flow between the column end plate and the casing in a fountain shape, and from the casing inner wall. A filtering device having a flow channel structure that is fed into the leaf disk filter, then passes through the flow channel between the inner wall of the leaf disk filter and the outer wall of the column, and then flows out from one place on the circumference at the ring-shaped junction. A method for filtering a molten polymer, comprising: 6. The method for filtering a molten polymer according to claim 6, wherein the casing is arranged vertically with the support column end plate facing downward, and the molten polymer in the casing can be lowered and raised. A method for filtering a molten polymer.