JP6759707B2 - Screws, extruders and mixing devices - Google Patents

Description

The present invention relates to screws, extruders and mixing devices.

The screw for the extrusion molding machine is provided with a mixing device for kneading the resin. Mixing devices are classified into mixed type and crushed type. The mixed mixing device causes the resin to flow irregularly to make the temperature of the resin uniform. A crushing type mixing device applies a high shearing force to the resin to crush the particles and droplets inside the resin.

As a crushing type mixing device, a Maddock type mixing device is known. The Maddock-type mixing device is provided with an inflow groove portion in which the upstream side is open and an outflow groove portion in which the downstream side is open alternately in the circumferential direction. An overflow flight portion having a small outer diameter is provided at the boundary portion of the groove portions adjacent to each other in the circumferential direction. A narrow clearance is formed between the overflow flight section and the cylinder. When the resin gets over the overflow flight portion and flows into the adjacent groove portion, a high shearing force is applied to the resin (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 60-49907

In order to improve the dispersibility of the resin, a plurality of crushing type mixing devices having different clearances may be connected in the axial direction. A plurality of mixing devices are connected to each other via an annular part called a collar. The outer diameter of the collar is smaller than the outer diameter of the mixing device so that the resin is not blocked by the collar. Further, the outer diameter of the end portion of the mixing device is gradually reduced in order to suppress interference with other parts. Therefore, a region having a small outer diameter is formed at the boundary between the mixing devices. In this region, the clearance between the cylinder and the cylinder is large, so that the resin tends to stay. The retained resin is heated in the cylinder for a long time and deteriorates. When the deteriorated resin flows out from the retention portion, it is mixed into the resin molded product as a foreign substance, and the reliability of the product is lowered. When a high shearing force is applied to the resin in order to improve the dispersibility of the resin, shear heat generation is generated and the deterioration of the resin progresses.

An object of the present invention is to provide a screw, an extruder and a mixing device that enhance the dispersibility of the resin, suppress the deterioration of the resin, and prevent the resin from staying.

In the screw according to one aspect of the present invention, a plurality of mixing portions are provided side by side in the axial direction of the shaft member, and the mixing portion is provided with a plurality of flight parts arranged in the circumferential direction of the shaft member. The flight section includes a plurality of damming flight sections and a plurality of overflow flight sections having an outer diameter smaller than that of the blocking flight section, and the plurality of damming flight sections and the plurality of overflow sections are included. When the flight portions are alternately arranged in the circumferential direction, the flight portions of the adjacent mixing portions are connected in the axial direction, and one side in the axial direction is the upstream side and the other side in the axial direction is the downstream side. The outer diameter of the overflow flight portion of the mixing portion on the downstream side is larger than the outer diameter of the overflow flight portion of the mixing portion on the upstream side.

According to this configuration, a plurality of mixing portions are continuously arranged in the axial direction. A region having a small outer diameter is not formed at the boundary between the mixing portions. Therefore, the resin is less likely to stay at the boundary portion. Further, since the outer diameter of the overflow flight portion of the mixing portion on the downstream side is larger than the outer diameter of the overflow flight portion of the mixing portion on the upstream side, the shearing force applied to the resin and the shear heat generation can be adjusted.

For example, the plurality of mixing portions are arranged side by side in the axial direction while shifting the positions of the overflow flight portions one by one in the circumferential direction.

According to this configuration, the direction in which the resin gets over the overflow flight portion is the same in all the mixing portions. In any of the mixing portions, the direction of resin flow in the circumferential direction coincides with the direction of rotation of the shaft member. Therefore, the flow of the resin in the circumferential direction is stable.

For example, the plurality of flight portions are spirally provided on the outer peripheral surface of the shaft member.

According to this configuration, the rotation of the shaft member promotes the flow of the resin in the axial direction.

For example, at one end of the shaft member in the axial direction, a first tapered portion is provided in which the outer diameter of the shaft member gradually decreases toward the outside.

According to this configuration, the flight portion is less likely to interfere with other parts connected to the shaft member.

For example, the first tapered portion is provided with one or more scraping flight portions having the same outer diameter as the damming flight portion.

According to this configuration, the resin is unlikely to stay in the first tapered portion.

For example, the number of scraping flight units is smaller than the number of flight units provided in one mixing unit.

According to this configuration, other parts connected to the shaft member and the scraping flight portion are less likely to interfere with each other.

For example, the first tapered portion is provided with a plurality of the scraping flight portions at positions rotationally symmetric with respect to the central axis of the shaft member.

According to this configuration, the resin flow is symmetrical with respect to the central axis. Therefore, the flow of the resin is less likely to be biased.

The extruder according to one aspect of the present invention has a screw according to one aspect of the present invention.

According to this configuration, an extruder in which resin retention is unlikely to occur is provided.

In the mixing device according to one aspect of the present invention, a plurality of mixing portions are provided side by side in the axial direction of the shaft member, and the mixing unit is provided with a plurality of flight parts arranged in the circumferential direction of the shaft member. The plurality of flight sections include a plurality of damming flight sections and a plurality of overflow flight sections having an outer diameter smaller than that of the blocking flight section, and the plurality of damming flight sections and the plurality of overflow sections are included. When the flow flight portions are alternately arranged in the circumferential direction, the flight portions of the adjacent mixing portions are connected in the axial direction, and one side in the axial direction is the upstream side and the other side in the axial direction is the downstream side. The outer diameter of the overflow flight portion of the mixing portion on the downstream side is larger than the outer diameter of the overflow flight portion of the mixing portion on the upstream side.

According to this configuration, a plurality of mixing portions are continuously arranged in the axial direction. A region having a small outer diameter is not formed at the boundary between the mixing portions. Therefore, the resin is less likely to stay at the boundary portion. Further, since the outer diameter of the overflow flight portion of the mixing portion on the downstream side is larger than the outer diameter of the overflow flight portion of the mixing portion on the upstream side, the shearing force applied to the resin and the shear heat generation can be adjusted.

According to the present invention, there are provided a screw, an extruder and a mixing device that enhance the dispersibility of the resin, suppress the deterioration of the resin, and prevent the resin from staying.

FIG. 1 is a cross-sectional view of an extruder according to an embodiment. FIG. 2 is a side view of the mixing device viewed from a direction orthogonal to the central axis of the screw. FIG. 3 is a development view of the mixing device. FIG. 4 is a cross-sectional view orthogonal to the axial direction of the first mixing portion. FIG. 5 is a cross-sectional view orthogonal to the axial direction of the second mixing portion. FIG. 6 is a diagram showing a multi-stage mixing device of a comparative example. FIG. 7 is a diagram showing a mixing device of the present embodiment. FIG. 8 is an enlarged view of a tapered portion of the multi-stage mixing device of the comparative example. FIG. 9 is an enlarged view of the first tapered portion of the mixing device of the present embodiment. FIG. 10 is a schematic view of a film manufacturing apparatus. FIG. 11 is a diagram showing an example in which the number of mixing units is n.

FIG. 1 is a cross-sectional view of the extruder EXT according to the embodiment.

The extruder EXT has a screw SCR and a cylinder CYL. A hopper (not shown) is attached to the supply port SP of the cylinder CLY. The resin RES used as a molding material is charged into the cylinder CYL from the hopper. A heat jacket (not shown) is attached to the outer peripheral portion of the cylinder CLY. The resin RES flows downstream in the cylinder CYL heated by the heat jacket as the screw SCR rotates. Hereinafter, the upstream side in the flow direction of the resin RES is referred to as "upstream side", and the downstream side in the flow direction is referred to as "downstream side".

The screw SCR has a plurality of main flight MFs and a plurality of subflight SFs. The outer diameter of the main flight MF is slightly smaller than the inner diameter of the cylinder CYL. The resin RES does not pass through the clearance between the main flight MF and the cylinder CLY. The outer diameter of the subflight SF is smaller than the outer diameter of the main flight MF. The resin RES is subjected to shearing force by passing through the clearance between the subflight SF and the cylinder CLY. The main flight MF and sub flight SF are processed integrally with the screw shaft SA.

The extruder EXT has a supply unit 10, a compression unit 20, and a measuring unit 30. The supply unit 10, the compression unit 20, and the measurement unit 30 are provided in order from the upstream side. In the supply unit 10, the resin RES supplied from the supply port SP is transported to the downstream side by the main flight MF. In the compression unit 20, the resin RES supplied from the supply unit 10 is kneaded and compressed by the main flight MF and the sub flight SF. In the measuring unit 30, the resin RES kneaded and compressed by the compression unit 20 is transported to the downstream side by the main flight MF. The resin RES that has passed through the measuring unit 30 is supplied from the discharge port EP to a die (not shown).

The measuring unit 30 is provided with, for example, a plurality of kneading units 35. In the kneading section 35, the resin RES supplied from the compression section 20 is further uniformly kneaded by the mixing device provided in the screw SCR. In the present embodiment, for example, as a plurality of kneading portions 35, a first kneading portion 31 and a second kneading portion 32 are provided.

For example, a crushing type mixing device 100 is provided in the first kneading unit 31. The second kneading section 32 is provided with, for example, a mixing type mixing device 105. The mixing device 100 applies a high shearing force to the resin RES to crush the particles and bubbles inside the resin RES. The mixing device 105 makes the resin RES flow irregularly to make the temperature of the resin RES uniform.

As the crushing type mixing device 100, for example, a dam ring, a Milefer flight, a Maddock mixer, a Traveler mixer, a Dry mixer, a Unimelt (registered trademark) mixer and the like are used. In the first kneading unit 31, a multi-stage mixing device in which a plurality of mixing devices 100 are connected may be used in order to improve the dispersion performance.

As the mixed type mixing device 105, for example, a pin screw, a notch flight, a pin barrel, a groove mixer, a pineapple mixer, a dalmage mixer and the like are used. In the second kneading unit 32, a multi-stage mixing device in which a plurality of mixing devices 105 are connected may be used in order to improve the dispersion performance.

The screw SCR is composed of a plurality of parts including the mixing device 100 and the mixing device 105. Each part may be molded as an integral part or may be configured as a part independent of each other. When a plurality of parts are configured as independent parts, the respective parts are axially connected to each other via an annular part called a collar. A screw SCR obtained by connecting a plurality of independent parts is called a split screw. The screw SCR of the present embodiment is, for example, a split screw.

FIG. 2 is a side view of the mixing device 100 of the present embodiment as viewed from a direction orthogonal to the central axis AX of the screw SCR.

The mixing device 100 includes a shaft member AM and a screw portion 141. The shaft member AM and the threaded portion 141 are integrally molded. The screw portion 141 is provided on one end side of the shaft member AM. A screw hole 142 is provided on the other end side of the shaft member AM. The inner diameter of the entrance of the screw hole 142 is larger than that of other parts. The in-row portion of the other component is fitted into the entrance of the screw hole 142. The outer diameter of the shaft member AM is slightly smaller than the inner diameter of the cylinder CLY. The outer diameter of the shaft member AM is, for example, the same as the outer diameter of the main flight MF.

The central axis of the shaft member AM coincides with the central axis AX of the screw SCR. Hereinafter, the reference numeral AX is also used as a reference numeral of the central axis of the shaft member AM. Further, the extending direction of the central axis AX is referred to as an axial direction. The direction along the outer peripheral surface of the shaft member AM in the plane orthogonal to the central axis AX is called the circumferential direction of the shaft member AM. One side in the axial direction is the upstream side, and the other side in the axial direction is the downstream side.

The mixing device 100 has a plurality of grooves 120 arranged in the circumferential direction of the shaft member AM, and a plurality of dam rows DA arranged in the axial direction of the shaft member AM. The boundary between the adjacent grooves 120 is the flight 110. The plurality of grooves 120 are partitioned by a plurality of flights 110 arranged in the circumferential direction.

The dam row DA closes a part of the groove 120 every other dam 130 by a plurality of dams 130 arranged in the circumferential direction. The plurality of dam rows DA are arranged in the axial direction of the shaft member AM while shifting the positions of the grooves 120 blocked by the plurality of dams 130 one by one. The number of dam row DAs is three or more. The plurality of grooves 120 are spirally provided on the outer peripheral surface of the shaft member AM, for example. The rotation of the shaft member AM promotes the flow of the resin RES in the axial direction.

In this embodiment, the number of grooves 120 is, for example, eight. The number of dam row DAs is, for example, three. As a plurality of dam rows DA, a first dam row DA1, a second dam row DA2, and a third dam row DA3 are provided in order from the upstream side. In the first dam row DA1, four dams 130 that block a part of the first, third, fifth, and seventh grooves 120 are arranged side by side in the circumferential direction. In the second dam row DA2, four dams 130 that block a part of the second, fourth, sixth, and eighth grooves 120 are arranged side by side in the circumferential direction. In the third dam row DA3, four dams 130 that block a part of the first, third, fifth, and seventh grooves 120 are arranged side by side in the circumferential direction.

The mixing device 100 has a plurality of mixing unit MPs arranged in the axial direction. The plurality of mixing unit MPs are axially partitioned by a plurality of dam rows DA. In the present embodiment, a first mixing unit MP1 and a second mixing unit MP2 are provided as a plurality of mixing unit MPs. The first mixing unit MP1 is arranged between the first dam row DA1 and the second dam row DA2. The second mixing unit MP2 is arranged between the second dam row DA2 and the third dam row DA3.

FIG. 3 is a developed view of the mixing device 100. FIG. 4 is a cross-sectional view orthogonal to the axial direction of the first mixing unit MP1. FIG. 5 is a cross-sectional view orthogonal to the axial direction of the second mixing unit MP2. The flight unit 110A described at the top in FIGS. 4 and 5 is a flight unit 110A belonging to the same flight 110.

As shown in FIG. 3, the flight 110 has a plurality of flight units 110A. The plurality of flight sections 110A are axially partitioned by a plurality of dam rows DA. The mixing unit MP is provided with a plurality of flight units 110A that partition the plurality of grooves 120. The plurality of flight portions 110A are arranged in the circumferential direction of the shaft member AM. The plurality of flight portions 110A are spirally provided on the outer peripheral surface of the shaft member AM, for example. The flight units 110A of the adjacent mixing units MP are connected in the axial direction.

The plurality of flight units 110A includes a plurality of damming flight units 111 and a plurality of overflow flight units 112. The overflow flight portion 112 has a smaller outer diameter than the damming flight portion 111. The plurality of damming flight portions 111 and the plurality of overflow flight portions 112 are alternately arranged in the circumferential direction.

As shown in FIGS. 4 and 5, the outer diameters of the damming flight portions 111 of each mixing portion MP are equal to each other. The outer diameter R0 of the damming flight portion 111 is slightly smaller than the inner diameter RC of the cylinder CYL. The outer diameter R0 of the damming flight portion 111 is, for example, the same as the outer diameter of the main flight MF. The resin RES does not pass through the clearance between the damming flight portion 111 and the cylinder CLY.

The outer diameter of the overflow flight section 112 differs for each mixing section MP. The outer diameter of the overflow flight section 112 is smaller as the mixing section MP on the upstream side is larger. In the present embodiment, the first mixing unit MP1 is arranged on the upstream side of the second mixing unit MP2. Therefore, the outer diameter R1 of the overflow flight portion 112 of the second mixing portion MP2 on the downstream side is larger than the outer diameter R1 of the overflow flight portion 112 of the first mixing portion MP1 on the upstream side. The resin RES passes through the clearance between the overflow flight section 112 and the cylinder CLY. Shear force is applied to the resin RES by passing the resin RES through the clearance between the overflow flight portion 112 and the cylinder CLY.

The larger the outer diameter of the overflow flight portion 112, the smaller the clearance between the overflow flight portion 112 and the cylinder CLY (hereinafter referred to as the overflow flight gap). In the present embodiment, the overflow flight gap G1 of the first mixing unit MP1 is larger than the overflow flight gap G2 of the second mixing unit MP2. The smaller the overflow flight gap, the greater the shearing force applied to the resin RES. Therefore, the shearing force increases from the upstream side to the downstream side. The particles and droplets inside the resin RES are gradually crushed while flowing downstream. Therefore, the shear heat generation becomes small.

By adjusting the overflow flight gap G1 of the first mixing unit MP1 and the overflow flight gap G2 of the second mixing unit MP2, the shearing force applied to the resin RES and the shear heat generation can be adjusted.

The mixing device 100 is suitable for screw SCR of resins having low thermal stability such as polyvinyl chloride resin, polyamide resin and cyclic olefin resin, and resins requiring high shearing force for kneading such as polyvinyl chloride resin. Can be used for. The thermal stability of the resin indicates the resistance to deterioration of the resin in the extruder. Examples of the resin deterioration phenomenon in the extruder include cross-linking and decomposition mainly due to heat, and oxidation mainly due to heat and oxygen.

As shown in FIG. 3, the flight 110 is provided with, for example, a damming flight portion 111 and an overflow flight portion 112 alternately provided in the axial direction. The plurality of mixing units MP are arranged side by side in the axial direction while shifting the positions of the overflow flight units 112 one by one in the circumferential direction. The direction in which the resin RES gets over the overflow flight portion 112 is the same in all mixing portions MP. In any of the mixing unit MPs, the direction of flow of the resin RES in the circumferential direction coincides with the direction of rotation of the shaft member AM. Therefore, the flow of the resin RES in the circumferential direction is stable.

The groove 120 has a plurality of groove portions 120A partitioned axially by a plurality of dam rows DA. The plurality of groove portions 120A include an inflow groove portion 121 and an outflow groove portion 122. The inflow groove portion 121 is a groove portion 120A in which the upstream side is open and the downstream side is closed by the dam 130. The outflow groove portion 122 is a groove portion 120A in which the downstream side is open and the upstream side is closed by the dam 130.

In the mixing unit MP, a plurality of inflow groove portions 121 and a plurality of outflow groove portions 122 are alternately arranged in the circumferential direction. The inflow groove portion 121 of the first mixing portion MP1 and the outflow groove portion 122 of the second mixing portion MP2, which are adjacent to each other in the axial direction, are axially partitioned by a dam 130. The outflow groove portion 122 of the first mixing portion MP1 and the inflow groove portion 121 of the second mixing portion MP2 that are adjacent to each other in the axial direction are connected to each other.

The resin RES that has flowed from the compression section 20 (see FIG. 1) into the inflow groove section 121 of the first mixing section MP1 gets over the overflow flight section 112 and is adjacent to the first mixing section MP1 in the circumferential direction. Inflow to. The resin RES that has flowed into the outflow groove portion 122 flows into the inflow groove portion 121 of the second mixing portion MP2 that is adjacent in the axial direction.

The resin RES that has flowed into the inflow groove portion 121 of the second mixing portion MP2 passes over the overflow flight portion 112 and flows into the outflow groove portion 122 of the second mixing portion MP2 that is adjacent in the circumferential direction. The resin RES that has flowed into the outflow groove portion 122 of the second mixing portion MP2 is supplied to the mixing device 105 (see FIG. 1) by the main flight MF provided on the downstream side.

At one end of the shaft member AM in the axial direction, a first tapered portion TP1 is provided in which the outer diameter of the shaft member AM gradually decreases toward the outside. At the other end of the shaft member AM in the axial direction, a second tapered portion TP2 is provided in which the outer diameter of the shaft member AM gradually decreases toward the outside. The first tapered portion TP1 is provided on the outside of the dam row DA provided on one end side in the axial direction, for example, among the plurality of dam row DAs. The second tapered portion TP2 is provided outside, for example, the dam row DA provided on the other end side in the axial direction among the plurality of dam row DAs. The presence of the first taper portion TP1 and the second taper portion TP2 makes it difficult for the dam 130 and the flight portion 110A to interfere with other components connected to the shaft member AM.

The first tapered portion TP1 located on the upstream side is provided with one or more scraping flight portions 113 having the same outer diameter as the damming flight portion 111. The number of scraping flight units 113 is smaller than the number of flight units 110A provided in one mixing unit MP. For example, the first tapered portion TP1 is provided with a plurality of scraping flight portions 113 at positions rotationally symmetric with respect to the central axis AX of the shaft member AM. In FIG. 3, the second taper portion TP2 located on the downstream side is not provided with the scraping flight portion 113, but the second taper portion TP2 is also scraped in the same manner as the first taper portion TP1. The flight section 113 may be provided.

Hereinafter, the effect of the screw SCR of the present embodiment will be described with reference to a comparative example. FIG. 6 is a diagram showing a multi-stage mixing device 104 of a comparative example. FIG. 7 is a diagram showing the mixing device 100 of the present embodiment. FIG. 8 is an enlarged view of the tapered portion TP of the multi-stage mixing device 104 of the comparative example. FIG. 9 is an enlarged view of the first tapered portion TP1 of the mixing device 100 of the present embodiment.

As shown in FIG. 6, the multi-stage mixing device 104 has a plurality of mixing devices 101 connected in the axial direction. The mixing device 101 is provided with only one mixing unit MP. The taper portion TP is not provided with a scraping flight portion. The plurality of mixing devices 101 are connected to each other via an annular part called a collar 103. The outer diameter of the collar 103 is smaller than the outer diameter of the mixing device 101 so that the resin RES is not blocked by the collar 103.

In the multi-stage mixing device 104, a region having a small outer diameter is formed at the boundary between the mixing devices 101. In this region, the clearance between the cylinder and the CYL is large, so that the resin RES tends to stay.

For example, the resin RES that has flowed out from the outflow groove portion 122 of the mixing device 101 on the upstream side spreads in the circumferential direction along the boundary portion. The resin RES spread in the circumferential direction adheres to the inner peripheral surface of the cylinder CYL and stays as it is. The retained resin RES is heated in the cylinder CYL for a long time and deteriorates. When the deteriorated resin RES flows out from the retention portion, it is mixed into the resin molded product as a foreign substance, and the reliability of the product is lowered.

As shown in FIG. 7, in the mixing device 100 of the present embodiment, a plurality of mixing unit MPs are continuously arranged in the axial direction. A region having a small outer diameter is not formed at the boundary between the mixing portions MP. Therefore, the resin RES is less likely to stay at the boundary portion.

For example, the resin RES that has flowed out from the outflow groove portion 122 of the mixing portion MP on the upstream side directly flows into the inflow groove portion 121 of the mixing portion MP on the downstream side. Since the outflow groove portion 122 of the mixing portion MP on the upstream side and the inflow groove portion 121 of the mixing portion MP on the downstream side are connected, it is difficult for the resin RES to spread in the circumferential direction along the boundary portion. Since the retention of the resin RES is suppressed, the reliability of the resin molded product is high.

Further, as shown in FIG. 8, in the multi-stage mixing device 104, the taper portion TP is not provided with the scraping flight portion. Therefore, the resin RES supplied from the compression portion 20 by the main flight MF spreads in the circumferential direction along the taper portion TP. The resin RES spread in the circumferential direction adheres to the inner peripheral surface of the cylinder CLY and stays as it is.

As shown in FIG. 9, in the mixing device 100 of the present embodiment, one or more scraping flight portions 113 are provided in the first taper portion TP1. Therefore, the resin RES spread in the circumferential direction is immediately scraped off by the scraping flight unit 113. Therefore, the resin RES is unlikely to stay in the first tapered portion TP1.

Further, in the present embodiment, the number of scraping flight units 113 is smaller than the number of flight units 110A provided in one mixing unit MP. Therefore, other parts connected to the shaft member AM and the scraping flight portion 113 are less likely to interfere with each other. Further, the first tapered portion TP1 is provided with a plurality of scraping flight portions 113 at positions rotationally symmetric with respect to the central axis AX of the shaft member AM. Therefore, the flow of the resin RES is symmetrical with respect to the central axis AX. Therefore, the flow of the resin RES is less likely to be biased.

FIG. 10 is a schematic view of the film manufacturing apparatus 1000 having the screw SCR of the present embodiment.

The film manufacturing apparatus 1000 includes an extruder 1001, a gear pump 1002, a filter changer 1003, a die 1004, a film forming unit 1005, a foreign matter inspection device 1006, and a winder 1007. As the extruder 1001, the extruder EXT of the present embodiment described above is used. In the film manufacturing apparatus 1000 of the present embodiment, since the screw SCR of the present embodiment is used in the extruder 1001, a highly reliable film can be manufactured.

Although preferred embodiments of the present invention have been described above, the present invention is not limited to such embodiments. The contents disclosed in the embodiments are merely examples, and various modifications can be made without departing from the spirit of the present invention. Appropriate changes made without departing from the spirit of the present invention naturally belong to the technical scope of the present invention. All inventions that can be appropriately modified and implemented by those skilled in the art based on the above-mentioned inventions also belong to the technical scope of the present invention as long as the gist of the present invention is included.

For example, in the above embodiment, an example in which the screw SCR is composed of a plurality of independent parts has been described, but the configuration of the screw SCR is not limited to this. For example, the screw SCR may be an integrated screw in which a plurality of parts are integrally molded.

Further, in the above embodiment, an example in which the number of grooves 120 is eight is shown, but the number of grooves 120 is not limited to this. Since the same number of inflow groove portions 121 and outflow groove portions 122 are provided, the number of grooves 120 is an even number. In order to improve the dispersibility of the resin RES, it is preferable that four or more grooves 120 are provided.

Further, in the above embodiment, an example in which the number of mixing unit MPs is two is shown, but the number of mixing unit MPs is not limited to this. The number of mixing unit MPs may be two or more. For example, FIG. 11 is a diagram showing an example in which the number of mixing unit MPs is n (n is an arbitrary integer of 2 or more).

The mixing device 100 is provided with (n + 1) dam rows DA arranged in an axial direction. N number of mixing unit MPs are axially partitioned by (n + 1) dam rows DA. The (n + 1) dam rows DA are arranged in the axial direction of the shaft member AM while shifting the positions of the grooves 120 blocked by the plurality of dams 130 one by one. The n mixing units MP are arranged side by side in the axial direction while shifting the positions of the overflow flight units 112 one by one in the circumferential direction.

The outer diameter of the overflow flight section 112 of the n mixing section MPs increases in order along the order in which the plurality of mixing section MPs are arranged. For example, the outer diameter of the overflow flight portion 112 is larger as the mixing portion MP located on the downstream side is larger. As a result, the clearance between the cylinder CLY and the overflow flight portion 112 becomes larger as the mixing portion MP located on the upstream side increases.

100 Mixing device 110A Flight section 111 Damping flight section 112 Overflow flight section 113 Scraping flight section AM Shaft member EXT Extruder MP Mixing section SCR Screw TP1 First taper section

Claims (9)

A plurality of mixing portions are provided side by side in the axial direction of the shaft member.
A plurality of flight portions arranged in the circumferential direction of the shaft member are provided in the mixing portion.
The plurality of flight sections include a plurality of damming flight sections and a plurality of overflow flight sections having an outer diameter smaller than that of the blocking flight section.
The plurality of damming flight portions and the plurality of overflow flight portions are alternately arranged in the circumferential direction.
The flight portions of the adjacent mixing portions are connected in the axial direction.
When one side in the axial direction is the upstream side and the other side in the axial direction is the downstream side
Than the outer diameter of the overflow flight portion of the mixing unit upstream, towards the outer diameter of the overflow flight portion of the mixing unit of the downstream side rather large,
At one end of the shaft member in the axial direction, a first tapered portion is provided so that the outer diameter of the shaft member gradually decreases toward the outside.
A screw provided with one or more scraping flight portions having the same outer diameter as the damming flight portion in the first tapered portion . The screw according to claim 1, wherein the plurality of mixing portions are arranged side by side in the axial direction while shifting the positions of the overflow flight portions one by one in the circumferential direction. The screw according to claim 1 or 2, wherein the plurality of flight portions are spirally provided on the outer peripheral surface of the shaft member. The screw according to any one of claims 1 to 3, wherein the number of scraping flight sections is smaller than the number of the flight sections provided in one mixing section. The screw according to claim 4 , wherein the first tapered portion is provided with a plurality of the scraping flight portions at positions rotationally symmetrical with respect to the central axis of the shaft member. An extruder having the screw according to any one of claims 1 to 5 . A plurality of mixing portions are provided side by side in the axial direction of the shaft member.
A plurality of flight portions arranged in the circumferential direction of the shaft member are provided in the mixing portion.
The plurality of flight sections include a plurality of damming flight sections and a plurality of overflow flight sections having an outer diameter smaller than that of the blocking flight section.
The plurality of damming flight portions and the plurality of overflow flight portions are alternately arranged in the circumferential direction.
The flight portions of the adjacent mixing portions are connected in the axial direction.
When one side in the axial direction is the upstream side and the other side in the axial direction is the downstream side
Than the outer diameter of the overflow flight portion of the mixing unit upstream, towards the outer diameter of the overflow flight portion of the mixing unit of the downstream side rather large,
At one end of the shaft member in the axial direction, a first tapered portion is provided so that the outer diameter of the shaft member gradually decreases toward the outside.
A mixing device provided with one or more scraping flight portions having the same outer diameter as the damming flight portion in the first tapered portion . The number of the scraping flight units is smaller than the number of the flight units provided in one of the mixing units.
The mixing device according to claim 7. The first tapered portion is provided with a plurality of scraping flight portions at positions rotationally symmetric with respect to the central axis of the shaft member.
The mixing device according to claim 8.

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