JP2003236831A - Twin-screw kneading extruder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure relieving of a resin and prevent a temperature from rising by removing the tip of a joint part formed by an arc-like inner hole of a cylinder bore and thereby, forming a notched part. <P>SOLUTION: This twin-screw kneading extruder structurally has a notched part (50) formed in a direction at right angle to the axis by removing the tip of the joint part (2M) formed by two arc-like inner holes (2H) in a section at right angle to each of the axes of the cylinder bores (2N) of a conveyance part (2b1 and 2b2) and a kneading part (2c). <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a twin-screw kneading extruder, and more particularly, a notch is formed by removing one or both of the tips of a joint formed in the upper and lower portions of a cylinder inner hole of a cylinder. However, the present invention relates to a new improvement for securing a resin escape place by the cutout portion and enabling commercialization while suppressing a decrease in energy consumption and a rise in resin temperature.

[0002]

2. Description of the Related Art As a twin-screw kneading extruder of this type which has been conventionally used, Patent No. 32 shown in FIGS.
The configuration of Japanese Patent No. 24931 can be mentioned. That is, in FIG. 2, what is indicated by reference numeral 1 is a twin-screw kneading extruder, and in the inner hole 2H of the cylinder 2 of this two-screw kneading extruder 1, two screws 3a and 3b which are meshed with each other are rotatable. Is inserted and built into. The cylinder 2 of this twin-screw kneading extruder 1 has an upstream end 2 to which the kneading material P is supplied.
From A to the downstream end 2B, a material supply section A, a transport section B1, B in order.
2, a kneading section C, a deaeration section D and a discharge section E.

Corresponding to the structure of the twin-screw kneading extruder 1, the cylinder 2 has a material supply cylinder 2a having a supply port 4 formed therein, two transport cylinders 2b1 and 2b2, a kneading cylinder 2c, and a degassing port 5. Each of the block cylinders of the deaeration cylinder 2d and the discharge cylinder 2e in which is formed is connected in the axial direction. Each of the block cylinders 2a to 2e is provided with a heating and cooling device (not shown) so that the temperature of the kneading material P suitable for the kneading condition can be controlled. The two screws 3a and 3b correspond to the configuration of the twin-screw kneading extruder 1 and have a material supply section A, a transport section B1,
B2, deaeration part D and discharge part E are full flight screws 3
F, the kneading section C is composed of a kneading disc 3D,
It is rotationally driven at the same rotational speed by a driving device (not shown) provided at the end of the material supply cylinder 2a. In the case shown in FIG. 2, the two screws 3a and 3b are rotationally driven in the same direction, but they may be rotationally driven in different directions by appropriately combining the screws 3a and 3b.
Further, the two screws 3a and 3b are configured by combining a large number of reconfigurable screw pieces so that the kneading state can be changed in accordance with the kneading characteristics of the kneading material P.

The twin-screw kneading extruder 1 configured as described above
The two transport section cylinders 2b1 and 2b2 and the kneading section cylinder 2c are, as a first conventional example, two screws 3a,
When 3b rotates in the same direction, as shown in FIG. 3 and when it rotates in different directions, as shown in FIG. 4, a plurality of grooves 2M are respectively formed in the two arc portions 2Q, 2R of the inner hole 2H in the axial direction in a cross section perpendicular to the axis. Are provided continuously. That is, an enlarged portion of the flow passage cross section is formed by the groove 2M in the flow direction of the kneading material P that rotates and flows along the inner hole 2H, and each groove 2M has a cross-sectional shape in a cross section perpendicular to the axis and the groove bottom surface and the screws 3a, 3b. The rotation outer circumference (flight outer circumference) of the screw 3a, 3b
It is formed in a smooth curved shape so that it gradually narrows in the direction of rotation. What is shown in FIG. 7 is a typical cross-sectional shape of the groove 2M, that is, a first arc 2M ₁ having a first radius of curvature R1 that is small in the rotation direction of the screws 3a and 3b and a second curvature that is larger than the first radius of curvature R. A groove bottom surface shape is formed by smoothly connecting to the second arc 2M ₂ having the radius R2. Also,
The first circular arc 2M ₁ is located on the front side along the rotation direction of the screws 3a, 3b, and the second circular arc 2M ₂ is the screw 3a,
It is located on the rear side along the rotation direction of 3b. The shape of the bottom surface of the groove is not limited to the shape in which the circular arcs 2M ₁ and 2M ₂ are connected, and it may be a single curved line, or two or more straight lines, or a curved line including straight lines and circular arcs or a smooth curved line. May be connected.

The screws 3a, 3 are constructed as described above.
In the twin-screw kneading extruder 1 in which b is rotatably driven, granular or powdery resin in which powdery material having an average particle diameter of 10 μm or less is mixed by several tens percent or more from the supply port 4 of the material supply cylinder 2a. When the material or the kneading material P of the powdery resin material as a whole is supplied, the kneading material P is 2 in the cross section perpendicular to the inner hole 2H of the cylinder 2.
Screw 3 while rotating along two circular arcs 2Q and 2R
Due to the transport action of a and 3b, they are sequentially transported in the downstream direction (the tip direction of the cylinder 2) in a filled state. During this time, the kneading material P is heated from the outside by the heating device provided in the cylinder 2, and the inner hole 2H surface of the cylinder 2 and the screw 3 are also heated.
The resin material rises in temperature and melts due to the kneading action with a and 3b and the friction between the kneading materials P. The melting phenomenon of the resin material starts in the transition region from the transport sections B1 and B2 to the kneading section C, and the kneading material P is kneaded in a molten state on the downstream side. The resin material in a molten state, that is, the kneading material P is a fluid substance having high viscosity, and its deformation rate becomes low.

Therefore, the kneaded material P in the molten state has the inner hole 2
When flowing along H, as shown in FIG. 9 at the start portion of the groove 2M, it is not possible to immediately follow the rapid expansion of the flow path cross section, and a space Q is generated at the expansion start portion. The space Q is formed so as to axially communicate with the downstream end of the kneading section cylinder 2c along the start portion of each groove 2M. Although the gas (in most cases, air) contained in the kneading material P interposed between the particles of the powdery material does not easily escape and is transported in the cylinder 2 in the downstream direction while being contained in the kneading material P. The gas heated by the temperature rise of the kneading material P expands its volume and its pressure increases. The gas whose pressure becomes higher easily escapes from the kneading material P due to a decrease in internal pressure in the groove 2M with an enlarged flow passage cross section, and passes through the space Q to the degassing cylinder 2d on the downstream side which is a low pressure part. It escapes and is deaerated from the deaeration port 5 to the outside of the cylinder 2. That is, the volume is sharply increased at the first arc 2M ₁ having the first radius of curvature R1, and the volume is gradually decreased at the second arc 2M ₂ having the second radius of curvature R2. The groove 2M is the kneading section cylinder 2
Although it is formed up to the downstream end of c and is not formed in the deaerating cylinder 2d, the screws 3a and 3b that are rotationally driven in the kneading cylinder 2c are kneading discs 3D, and the back of the rotating flight is negative. Since the space is formed as a pressure, the gas flowing through the space Q formed in the groove 2M easily flows to the degassing cylinder 2d through the space on the back surface of the kneading disk 3D.

In the degassing section D, the kneading material P is mixed with the screw 3
Since the grooves of a and 3b are not completely filled and a space is formed on the back surface of the flight of the full flight screw 3F, the air flowing from the kneading section C easily reaches the deaeration port 5 via the back surface of the flight. . The molten kneaded material P filled in the groove 2M excluding the space Q is the screw 3a,
3b It becomes smooth gradually shallower in the direction of rotation and the original inner hole 2
The kneading material P, which rotates with the screws 3a and 3b, is easily dragged out of the groove bottom that recovers to H, and easily comes out.
It does not stay in the groove 2M. That is, the kneading material P
Is transported to the downstream side while being rotated in the inner hole 2H of the cylinder 2 by the screws 3a and 3b, while being transported to the transport portions B1 and B2.
By repeatedly crossing the groove 2M in the kneading section C, the gas contained in the kneading material P is separated and kneaded while being deaerated.

Next, as a second conventional example, when the two screws 3a, 3b rotate in the same direction, as shown in FIG. 5, the transport section cylinders 2b1, 2b2 and the kneading section cylinder 2 are shown.
In the cross section perpendicular to the axis of c, the two arc portions 2 of the inner hole 2H
Notch 2K at each of the two joints 2N of Q and 2R
Are continuously provided in the axial direction. An enlarged portion of the flow path cross section is formed by the cutouts 2K in the flow direction of the kneading material P that rotates and flows along the inner hole 2H, and each cutout 2K is
The cross-sectional shape in the cross section perpendicular to the axis gradually narrows the distance between the notched bottom surface and the outer circumference of the rotation (flight outer circumference) of one of the screws 3a or 3b in the rotation direction of the screw 3a or 3b, that is, from the inner hole 2H space portion. Is formed in a smooth curved line or a straight line so as to gradually narrow the gap between the rotation outer circumference of the screw 3a or 3b, which approaches the portion 2N and rotates in the direction along the arc, and the bottom surface of the notch 2K in the rotation direction. There is. What is shown in FIG. 8 is a typical cross-sectional shape of the cutout 2K, and the cutout bottom surface shape is formed by one arc having a radius of curvature R3. The shape of the cutout bottom surface is not limited to the shape of one circular arc, and may be formed by a straight line or two or more curved lines or a smooth connection of straight lines.

The screws 3a, 3 are constructed as described above.
In the twin-screw kneading extruder 1 in which b is driven to rotate in the same direction, the kneading material P containing the powdery material supplied from the supply port 4 of the material supply cylinder 2a is the same as in the case of the first conventional example described above. Melt kneaded. The transport section cylinders 2b1, 2
In b2 and the kneading section cylinder 2c, when the kneading material P in a molten state flows along the inner hole 2H, when it reaches the notch 2K of the joining section 2N from the circular arc sections 2Q and 2R of the inner hole 2H. As shown in FIG. 10, it is not possible to immediately follow the rapid expansion of the flow path cross section, and a space Q ′ is generated at the expansion start portion. This space Q'is formed in axial communication with the downstream end of the kneading section cylinder 2c along the starting portion of each notch 2K. Similarly to the above-described first embodiment, the gas contained in the kneading material P is degassed from the degassing port 5 of the degassing unit cylinder 2d to the outside of the cylinder 2 through the space Q '. The kneaded material P in the molten state, which is filled in the cutout 2K except for the space Q ', does not escape from the cutout 2K and stay in the same manner as in the first conventional example. That is,
While the kneading material P is transported to the downstream side while being rotated in the inner hole 2H of the cylinder 2 by the screws 3a and 3b, the cutouts 2K are repeatedly cut in the transport portions B1 and B2 and the kneading portion C.
The gas contained in the kneading material P is separated and degassed by kneading while traversing.

Further, FIG. 6 shows a third embodiment of the transport section cylinders 2b1 and 2b2 and the kneading section cylinder 2c of the twin-screw kneading extruder 1 in which two screws 3a and 3b rotate in the same direction. In the cross section perpendicular to the axis, the plurality of grooves 2M of the first embodiment described above and the two notches 2 of the second embodiment.
It is formed together with K. In the twin-screw kneading extruder 1 configured as described above, the action of the groove 2M in the first conventional example and the action of the notch 2K in the second conventional example similarly occur at each location.

Further, in the above-mentioned conventional example, the cylinder 2
Due to the plurality of grooves 2M or two notches 2K provided in the inner hole 2H in the axial direction, the cross-section of the flow passage of the kneading material P that is rotationally moved along the inner hole 2H is repeated, and the kneading material P is By performing a lot of positional exchange of the materials, the kneading and dispersion is more effectively performed, and the kneading is performed more uniformly. Furthermore, the shearing force in the kneading material P is weakened in the enlarged portion of the flow path cross section, so that the temperature rise is suppressed and the kneading material P is prevented from unnecessarily rising in temperature. At the boundary between the material supply cylinder 2a and the transport cylinder 2b1 downstream thereof and at the boundary between the kneading cylinder 2c and the degassing cylinder 2d downstream thereof, the cross-sectional shape of the inner holes 2H perpendicular to the axis is circular. A transition region having a cross-sectional shape that smoothly changes from an arc shape to the groove 2M or the notch 2K is provided. Since the transition region of the cross-sectional shape is provided in the changing portion of the cross section perpendicular to the axis of the inner hole 2H, there is no corner portion and the kneaded material P
Does not stay.

Next, the operation will be described. First, the kneading material in which the powdery material supplied from the supply port of the material supply unit into the cylinder inner hole where the screw is rotationally driven is
The material is sequentially transported from the material supply section to the transport section, the kneading section, the degassing section, and the discharging section by the transporting action of the screw while rotating along the two arcuate portions in the cross section perpendicular to the axis of the inner hole of the cylinder. During this time, the kneading material is melt-kneaded, the gas contained in the kneading material is separated and discharged from the degassing port of the degassing section, and the homogeneously kneaded molten resin is extruded from the discharge section, that is, the tip of the cylinder. When the molten resin, which is a substance with high viscosity in the molten state, has a relatively low deformation rate and the cross-section of the flow channel in the flowing direction of the molten resin increases rapidly, it cannot immediately follow the enlarged shape at the portion where the enlargement starts and the enlargement starts. Space is generated in a part of the section. The grooves provided in the two arc portions in the cross section perpendicular to the axis of the cylinder inner hole cause a rapid expansion of the flow passage cross section with respect to the molten resin flowing along the two arc portions, and a space is generated in each groove. This space is formed in each groove so as to communicate with each other in the axial direction of the transport section and the kneading section. The gas separated from the kneading material in the transport section and the kneading section uses the axial space formed by communicating along each groove of the transport section and the kneading section as a flow path, and the low-pressure degassing section on the downstream side of the kneading section. To be discharged from the deaeration port of the deaeration unit. Since the grooves are formed in a smooth shape that rapidly expands in the screw rotation direction and then gradually narrows, the cross-section of the flow path is changed more effectively, and the kneading material that tends to stay in the grooves is Due to the highly viscous cohesive property in the molten state, it is easily drawn between the cylinder bore and the screw. 2 in the cross section perpendicular to the axis of the cylinder bore where the two screws rotate in the same direction
The notch provided at the joining portion of the two arc portions causes an abrupt expansion of the cross section of the flow path with respect to the molten resin flowing along the two arc portions, and a space is generated there. It is formed so as to communicate in the axial direction of the kneading section. The gas separated from the kneading material in the transport section and the kneading section uses the axial space formed by communicating along the notches of the transport section and the kneading section as a flow path, and the low-pressure degassing section on the downstream side of the kneading section. To be discharged from the deaeration port of the deaeration unit. The notch has a gap between the outer circumference of one screw and the outer circumference of the screw that gradually narrows in the direction of rotation of the screw, that is, a notch for a screw that approaches the joint from the inner hole space and rotates along the arc. Since the space between the inner wall surface and the inner wall surface of the screw gradually decreases in the rotation direction, the other screw rotating in the same direction rotates along the arc portion and moves to the inner hole space portion at the notch. The change of the flow path cross section at the time of performing is performed more effectively. Further, since the notch is gradually narrowed in the rotation direction of one screw, the kneaded material that tends to stay in the notch easily becomes easily between the cylinder bore and the screw due to the highly viscous cohesive property in the molten state. Be drawn in. A groove and 2 provided in two arc portions in a cross section perpendicular to the axis of the cylinder inner hole in which the two screws rotate in the same direction.
The notch provided at the joining portion of the two arc portions causes an abrupt expansion of the cross section of the flow path with respect to the molten resin flowing along the two arc portions, and the above-described respective actions similarly occur at the respective locations. .

[0013]

Since the conventional twin-screw kneading extruder is constructed as described above, the following problems exist. That is, in the conventional twin-screw kneading extruder, basically, as shown in FIG. 11, since the tips of the joints of the pair of circular cylinders are formed in an upper and lower shape with an acute angle, When the left and right screws rotate, at each of the upper and lower joints, when the crests of the screws are located at the joints, there is less space for the resin to escape, and at that time, the resin pressure generated causes the resin to escape. The temperature will rise and the melting will be accelerated. Therefore, the resin temperature has increased more than necessary due to an increase in energy consumption (kw · hr / kg) for producing a product more than necessary. Further, as in the above-described conventional configuration, forming a groove or a notch in the inner wall of each cylinder requires a long processing time and is also a heavy burden in terms of cost.

The present invention has been made to solve the above problems, and in particular, by removing one or both of the tip portions of the joints formed in the upper and lower portions of the cylinder inner hole of the cylinder. An object of the present invention is to provide a twin-screw kneading extruder capable of forming a cutout portion, securing a resin escape place by the cutout portion, and suppressing the reduction of energy consumption and the rise of resin temperature for commercialization.

[0015]

A twin-screw kneading extruder according to the present invention has two interlocking screws rotatably incorporated in a cylinder inner hole of a cylinder, and a material supply section, a transport section,
In a twin-screw kneading extruder composed of a kneading section, a degassing section and a discharging section, the tip of a joint formed by two arc-shaped inner holes in a cross section perpendicular to the axis of the cylinder inner hole of the transport section and the kneading section. And a notch formed along the direction perpendicular to the axis, and the position of the notch is the end of the joint part of the cylinder inner hole of each cylinder and the cylinder inner hole. The distance from the center of the circle is 1.2 times or more, and the notch has a flat surface, and the notch is either the upper part or the lower part of the cylinder. Or it is the structure formed in both.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of a twin-screw kneading extruder according to the present invention will be described below with reference to the drawings.
It should be noted that the same or equivalent parts as those of the conventional example will be described using the same reference numerals, and the sectional configuration of the twin-screw kneading extruder 1 shown as the conventional configuration of FIG. 2 is the same as that of the present invention. The configuration will be referred to, the description thereof will be omitted to avoid duplication, and only the part different from the conventional one will be described.

The reference numeral 2N in FIG.
This is a cylinder inner hole in the cylinder 2, and this cylinder inner hole 2N shows a part of the upper portion of the cross section perpendicular to the axis of the cylinder segments of the transport parts 2b1 and 2b2 and the kneading part 2c of the cylinder 2 of FIG. That is, although FIG. 1 shows only the upper part, a similar structure exists in the lower part of the cylinder inner hole 2N, but it is omitted here.

Inside the cylinder inner hole 2N, a pair of screws 3a and 3b shown in FIG. 2 are provided so as to rotate in the same direction as shown by the arrows. Each screw 3a, 3b for 3b
A pair of arc-shaped inner holes 2H are formed in a state close to a circle formed along the rotation locus.

A joint portion 2MA (shown by a one-dot chain line in FIG. 1) in which the respective arcuate inner holes 2H are in contact with each other as in the conventional case is a joint portion 2MA along the same axis perpendicular direction as the cross section perpendicular to the axis of the cylinder 2. A notch 50 is formed by cutting and removing the tip end of the notch 50. The notch 50 is formed by a flat surface (not a flat surface, for example, it may be uneven or stepped).

The position of the notch 50 in the cylinder inner hole 2N is a distance 52 from a circle center 51 of the radius of the arcuate inner hole 2H, and this distance 52 is the same as the conventional joint shown in FIG. It is set to 1.2a or more, which is 1.2 times the distance a between the end 2Ma of the portion 2MA and the center 51 of the circle.

Therefore, the joint portion 2 of each arcuate inner hole 2H is formed.
Since the tip of MA is removed and the height is made higher than before by the amount of the notch 50, in order to suppress the increase in resin pressure and the increase in energy consumption when transporting and kneading the molten resin, It is possible to achieve commercialization while suppressing the resin temperature rise. Although only the upper part of the cylinder inner hole 2N is described in FIG. 1, the notch 50 can be formed in the upper part, the lower part, or both.

Example The applicant carried out the following experiment using the twin-screw kneading extruder according to the present invention. Experimental apparatus Twin-screw kneading extruder T _EX 65αII-35Pw-V Screw rotation speed 60 to 600 rpm Main motor capacity 300kw Experimental raw material AS pellets The experimental results are shown in Table 1 below.

[0023]

[Table 1] That is, according to the experimental results shown in Table 1 above, it is clear that both the resin temperature and the resin pressure are lower when the cylinder according to the present invention is used as compared with the conventional configuration.

[0024]

Since the twin-screw kneading extruder according to the present invention is constructed as described above, the following effects can be obtained. That is, since the notch portion is formed by removing the joining portion, that is, the tip end portion of the arcuate inner hole, the escape of the resin can be secured only by this notch portion, and the pressure and temperature rise of the resin can be suppressed. Therefore, it is possible to achieve commercialization while suppressing a rise in resin temperature.

[Brief description of drawings]

FIG. 1 is a sectional view showing a main part of a twin-screw kneading extruder according to the present invention.

FIG. 2 is a vertical sectional view showing the present invention and a conventional twin-screw kneading extruder.

3 is a shape diagram of the inner hole of FIG. 2. FIG.

FIG. 4 is a shape diagram of an inner hole in which a groove is provided in the cylinder of FIG.

5 is a shape diagram of an inner hole in which the cylinder of FIG. 2 is provided with a notch.

FIG. 6 is a shape diagram of an inner hole in a cross section perpendicular to the axis of FIG.

7 is a groove shape view of a cross section perpendicular to the axis of FIG.

8 is a cutaway shape view of a cross section perpendicular to the axis of FIG.

FIG. 9 is a flow chart of a conventional kneading material.

FIG. 10 is a flow chart of a conventional kneading material.

FIG. 11 is a cross-sectional view showing a main part of a conventional cylinder inner hole.

[Explanation of symbols]

2 cylinders 2N cylinder inner hole 2b1, 2b2 Transport Department 2c kneading section 2M joint 2H arc-shaped inner hole 3a, 3b screw 50 notch 51 Yen center 52 distance

Continued front page    (72) Inventor Hiroaki Shintani             1-6-1, Funakoshi-minami, Aki-ku, Hiroshima-shi, Hiroshima               Japan Steel Works, Ltd. F term (reference) 4F201 AP12 BA01 BK13 BK27 BK33                       BK34 BK75 BQ34 BQ60

Claims (4)

[Claims] 1. A cylinder inner hole (2N) of a cylinder (2) rotatably incorporating two mutually meshing screws (3a, 3b), a material supply section (2a), a transport section (2b1, 2b2), Kneading section (2c),
In a twin-screw kneading extruder composed of a degassing section (2d) and a discharging section (2e), a cylinder inner hole (2) of the transport section (2b1, 2b2) and the kneading section (2c)
(N) has a notch (50) formed along the direction perpendicular to the axis by removing the tip of the joint (2MA) formed by the two arcuate inner holes (2H) in the cross section perpendicular to the axis. A twin-screw kneading extruder characterized by: 2. The position of the notch (50) is determined by the end (2M) of the joint (2MA) of the cylinder inner hole (2N) of each cylinder (2).
The distance (5) between the a) and the circle center (51) of the cylinder bore (2H)
The twin-screw kneading extruder according to claim 1, which is 1.2 times or more of 2). 3. The twin-screw kneading extruder according to claim 1, wherein the notch (50) has a flat surface. 4. The biaxial according to claim 1, wherein the cutout portion (50) is formed in one or both of an upper portion and a lower portion of the cylinder (2). Kneading extruder.