JPS58104622A - Twin-shaft type continuous kneader with vent - Google Patents

Abstract

PURPOSE:To provide the titled kneader capable of increasing a kneading time to a material to be kneaded to carry out sufficient kneading by enlarging an L/D ratio and enhancing the supply force of the material by compensating the lowering of the rotary speed of a rotor with the increase of the L/D ratio by engagement in a feed part. CONSTITUTION:A feed part 5 is formed into a large diameter compared to other parts and supply flights 51 are mutually engaged in said feed part 5. In a first kneading part 6, a rotor 4 has a non-circular cross area and forms an outwardly protruded kneading blade 61 suitable for imparting shearing and stirring actions between the rotor 4 and the inner wall of a chamber 1 and between mutual spaces of the rotor 4. In addition, from the initial end part to the intermediate part of the kneading part 6 in an axial direction, the kneading blade 61 is continued to a sending blade part 62 in such a manner that twist with an appropriate lead angle is formed toward a direction gone away from the rotary direction of the rotor and, from this part to the terminal end thereof, a return blade part is formed so as to provide twist with a lead angle in an opposed direction. Therefore, stirring action is increased with the interference of the material and the generation of pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vented two-shaft continuous crosstalk machine used for crosswiring polymeric materials such as synthetic resins.

Conventionally, this kind of two-shaft continuous mixer generally has two rotatable rotors arranged in parallel in a chamber, each having a screw-shaped feed section in order from the material supply port side,
A mixing section equipped with kneading blades having an oval cross-sectional shape, etc., and a discharge section are arranged, and the material to be mixed, which is sequentially supplied from the material supply port of the chamber, is fed to the kneading section by the feed section. After melting and kneading in the kneading section, the mixture is continuously discharged from the discharge port of the chamber. The kneading section usually has a feed section in which the kneading blades are twisted in the direction of feeding the material to be mixed forward, and a return wing section in which the kneading blades are twisted in the direction of returning the material. It is provided over a range of areas.

With this configuration, depending on the material to be kneaded, the mixing time may be insufficient and sufficient kneading may not be achieved. Therefore, the L/D (ratio of length to diameter) of the rotor is increased, and the kneading section is moved in the axial direction.
A structure that can be installed at a specific location has also been adopted. In this structure, a constricted part is provided between the kneading parts in order to prevent a drop in the pressure of the material to be mixed in the kneading part and to prevent thermal deterioration of the material due to a sudden increase in the number of heating wires. Furthermore, in order to remove the volatile components contained in the paulownia wood in the crosstalk and prevent air bubbles from remaining in the product, a vent hole is provided and the air is degassed from there using a vacuum pump. When powdered materials are kneaded by the device, there is a problem that the unkneaded powder is sucked into the vacuum system through the constriction section and vented up at the degassing section.

This invention was made to solve the drawbacks of such two-screw continuous kneading machines, and when kneading powder-like materials under vacuum degassing, unkneaded powder is sucked into the vacuum system from a constriction part. First, it provides a structure that does not cause vent-up in the degassing section.

That is, the present invention provides a device that is a two-shaft continuous crosstalk machine, which has a constriction section between a first crosstalk section and a second crosstalk section, and has a deaeration hole, in which the pressure of the constriction section is reduced. The material passage in the constriction section is set so that the drop can be controlled within the range of 10 to 35 Kgf/cII, preferably 15 to 50 Kgf/cd, based on the value of ΔP in the following equation.

However, η, : Apparent viscosity of the t-tube part (Kgf-Sec/d
) η2 : Apparent viscosity of the communicating part (Kgf-see/
1) Ql: Flow rate of the tip part (7/s+1c) Ql: Flow rate of the communicating part (CIIl/cover) L: Longest side of the circular cross section) Wl: Circumferential length of the tip part σ) W2: Flow rate of the communicating part Height c-) tl: Gap between tip portions (C) t2: Gap between communication portions (σ) Examples of the present invention will be described below with reference to the drawings. 1st
In Figures 1 to 4, 1 is a chamber, 2 is a material supply port provided at one end of the chamber 1, and 3 is a discharge orifice constituting a material discharge port at the other end of the chamber 1. The chamber 1 is substantially cylindrical and has interconnected parallel parallel chambers 2
Two chambers are formed, and a discharge orifice 6 common to both chambers is provided. The material supply port 2 is provided with receiving means (not shown) that receives the material to be mixed and stuffs it into the chamber under pressure. Reference numeral 4 denotes a two-axis rotor arranged in parallel in the chamber 1. The rotor 4 is rotatably supported by the chamber 1 at its end, and is normally rotated synchronously in opposite directions by a motor, reducer, gear, etc. (not shown). It is configured.

In both the rotors 4, from the material supply port 2 side,
A screw-shaped first feed section 5 having a supply flight 51 with a constant groove depth between flights, a first crosstalk section 6, and a circular cross-sectional section that constitutes a throttle mechanism 7 together with a movable wall 72 of the chamber 1 to be described later. 71, a second feed section 8, a second crosstalk section 9, and a discharge section 10 are provided.

The feed section 5 is formed larger than other sections, and the supply flights 51 are meshed with each other.

In the illustrated example, the supply flight 51 is a five-thread screw, and 1 is also
In accordance with the rotor shape, a portion corresponding to the first feed portion 5 has a larger inner diameter than other portions.

In the first kneading section 6, the rotor 4 has a non-circular cross-sectional shape, which is suitable for providing shearing and stirring action between the rotor 4 and the inner wall of the chamber 1 and between the rotors 4, but the kneading blades protrude from three sides. A shape such as an oval cross section may also be adopted. In addition, in the axial direction, from the starting end to the middle part of the mixed line part B, the kneading blades 61 are continuously twisted at an appropriate lead angle in the direction of moving away from the rotating direction, that is, in the direction of feeding the material forward. From here to the end of the kneading section 6, the kneading blades 61 continue in the opposite direction, that is, in the direction in which the material is returned, with a twist of an appropriate lead angle (
Hereinafter, this portion is formed as a return wing portion 65). In this case, the length and torsion rate of the return vanes 63 are such that when the chamber contains a material to be mixed, the axial force applied to the material by the vanes 61 causes the material to flow through the discharge orifice 6.
The total axial travel of the material to be mixed through said chamber is such that the material is not sufficiently extruded through said receiving means.

It depends on how well it is accepted. The structure is such that shearing, stirring, dispersion, and other effects are enhanced due to material interference and pressure generation between the sending blade section 62 and the returning blade section 63.

Further, the circular cross-section section 71 is located at the end of the first kneading section 6, and a movable wall 72 is provided in the chamber 1 facing above and below the circular cross-section section 71, and the movable wall 72 and the circular cross-section section 71 constitutes the aperture mechanism 7. The movable wall 72 is moved in the radial direction of the chamber 1 by a driving means 76 such as an air cylinder, and the gap between its tip and the outer circumferential surface of the circular cross-section section 71 is changed.

A second feed section 8 located on the other side of the circular cross-section section 71
is formed in the same screw shape as the first feed section 5. Also, in this part of the chamber/bar 1 there is a deaeration hole 11.
A vacuum device (not shown) is connected to this degassing hole 11, and volatile components contained in the material being cross-wired are degassed by this.

Note that if the screw groove is filled with molten resin and the transport capacity of the screw is reduced, it will vent up through the deaeration hole 11 and suck the molten resin into the vacuum system, blocking the deaeration hole. When meshed, the flight exhibits the effect of scraping off the molten resin in the groove of the mating screw, increasing the transport capacity to the second crosstalk section 9 and increasing the amount of molten resin in the degassing hole 1.
1, it is possible to prevent vent-up and blockage from occurring.

The second mixing section 9, like the first mixing section 6, includes a kneading blade 91 and a pair of a sending blade section 92 and a return blade section 96. The discharge section 10 is located near the end of the rotor 4 in front of the second crosstalk section 9, and has straight blades.

Further, one side wall 61 of the discharge orifice 6 can be opened and closed, and by opening and closing the opening and closing operation, the opening spear of the orifice 6 is adjusted, thereby adjusting the discharge rate and discharge resistance of the kneaded material.

FIG. 5 shows another example of the throttle mechanism 7, in which the tip 74 of the movable wall 72 enters between the circular cross-sections 71 and 71, and when the flow path is most narrowed, the upper and lower tips 74 touch each other. The two shafts are in contact with each other so that the two shafts are isolated.

FIG. 6 shows yet another example of the throttling mechanism 7, which is arranged in a circular cross section 75 formed on two axes so as to be offset from each other, so that the annular shape of the material flow path is reduced on one side and The flow resistance of the material is increased in this portion by enlarging it.

FIG. 7 conceptually shows the shapes and dimensions of each part of the diaphragm mechanism 7, in which the circular cross-sectional part 71 has a length L in the axial direction,
Further, a tip gap t1 and a biaxial communication portion S (shaded portion) are formed around the movable wall 72. In addition,
In the case of the structure shown in FIG. 6, L is the dimension of the circular cross section, and the dimension between the opposite surfaces of both circular cross sections 75 is taken. t2 and horse are the width and height of the communication part S, and Ql is the tip gap t1
The flow rate passing through the communication section S, Q2 is the flow rate passing through the communication part S, Dl
are the outer diameter of the circular cross section 71, η1 and η! represent the apparent viscosity (Kgf-sec/cII) of the material passing through the tip gap t1 and the communication portion S, respectively. The circumferential dimension W1 of the omitted chip portion is expressed as W+=(71-(Dl+t+)-W2)X2.

In this configuration, the value of pressure drop ΔP shown by the following equation is 1
0~35 Kg f/(・d1 preferably 15~50
The dimensions of each part are set so that it can be controlled to Kgf/crA. Note that the dimensions of t, t2 are adjusted by moving the movable wall 72 up and down, but the configuration shown in FIG. 5 is preferable when it is desired to make the communication section S smaller through which the unmixed ζ ladder can easily pass. .

Next, the operation of the above device will be explained. The material to be mixed, which is continuously and quantitatively supplied by a feeder (not shown) or the like, is first sent forward in the axial direction by the feed section 5 on the starting end side of the rotor 4. In addition, since the supply flights 51 of the feed section 5 are in mesh with each other, a sufficiently large feed force is exerted even when the rotor 4 is rotated at a lower rotational speed than a general conventional machine. Also, materials with low bulk specific gravity, materials that are easily sticky, and slits! Materials that are easy to nib are also reliably fed.The mixed materials sent from the feed section 5 are
In the first mixing section 6 , the material is plasticized, melted, and kneaded by shearing, stirring, dispersion, etc., and then passes through a squeezing mechanism 7 and sent to a second kneading section 9 through a second feed section 8 .

Since the flow path dimensions of the throttling mechanism 7 are set within a predetermined range as described above, the pressure of the material in the first kneading section 6 and the second mixing section 9 can be properly controlled, and the heat generated by shearing can be controlled appropriately. The temperature rise is also properly controlled, the temperature of the material at both temperature lines is averaged, and uneven kneading is also prevented. Further, material sealing is performed by the molten material in the throttle mechanism 7 and the orifice 5 on the discharge end side, so that airtightness is obtained in the chamber 1 between them, and vacuum degassing is performed from the degassing hole 11. At this time, if a powder-like material is used, there is a risk that the unmixed powder will be drawn into the vacuum system, but by setting the flow resistance in the squeezing mechanism to a predetermined value as described above, the unmixed powder will be mixed in the first mixing section. This prevents powder from being sucked into the vacuum system.

Using a mixture of low-density polyethylene and carbon as the material, the production rate was set to 60 kg/h, the outer diameter D1 of the circular cross section was set to 49 mm, and the length L was set to 0.7σ, and the pressure loss of the throttle mechanism 7 was varied. As a result, characteristics as shown in FIG. 8 were obtained. In the figure, a curve 83 shows a change characteristic of the degree of vacuum with respect to pressure drop, a curve 84 shows a change characteristic of the powder suction rate, and a curve 85 shows a change characteristic of the resin temperature. It is clear from this that when the pressure drop ΔP is set to 10 Kgf/pi, the powder suction rate decreases rapidly and the degree of vacuum becomes stable. On the other hand, when the pressure drop ΔP becomes 35Kgf/- or more,
Because the flow resistance in the squeezing mechanism is too large, the temperature of the resin will rise rapidly, resulting in deterioration of the resin and burning of the filler, so the pressure drop ΔP is 3.
It should be less than 5 Kg f/tJ. Therefore, the pressure drop needs to be set in the range of 10 to 35 Kgf/m.

In addition, looking at the effect of the degree of vacuum on the degree of carbon dispersion,
As shown in FIG. 9, the degree of dispersion increases in proportion to the increase in the degree of vacuum. It is thought that when the degree of vacuum increases, the air in the mixed material is removed, the apparent viscosity of the mixed material increases, and the shear stress applied to the carbon particles increases, thereby improving the degree of dispersion.

As explained above, this invention takes advantage of the characteristics of the vented twin-screw kneader, and in particular sets the flow resistance in the throttling mechanism between the two hot wire sections to a predetermined range, and has the following various features. It has excellent effects. In other words, by increasing L/D, the mixing time increases and sufficient kneading is performed even for materials to be mixed, which were difficult to apply with conventional equipment.
In response to the decrease in rotor rotational speed due to an increase in /D, the throughput is increased by increasing the material supply force by meshing the feed sections. Furthermore, by setting the pressure drop in the throttling mechanism within a predetermined range, vacuum deaeration is performed well, and even when powder-like materials are kneaded, unmixed powder is not sucked into the vacuum system, and deaeration is prevented. This prevents vent-up in the parts and allows for stable operation and high-quality products.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a crosstalk machine showing an embodiment of the present invention, and FIGS. 2 to 4 are lines i-I, 1-1, and +V in FIG. 1, respectively.
-+V line sectional view, Figure 5 is a cross-sectional shape diagram showing another example of the aperture mechanism, Figure 6 is a horizontal cross-sectional shape diagram showing yet another example, and Figure 7 is the dimensions and shape of each part of the aperture mechanism. FIG. 8 is a diagram showing the relationship between the pressure drop at the throttle part and various conditions, and FIG. 9 is a diagram showing the relationship between the degree of vacuum and the degree of carbon dispersion. 1. Chamber, 2. Material supply port, 6. Discharge orifice, 4. Rotor, 5. Feed m, 6-11°1 cross section, 7. Throttle mechanism, 71. Circular cross section, 72..
- Movable wall, 9... second kneading section. Patent applicant Kobe Steel, Ltd.

Claims (1)

[Claims] 1. Having a material supply port at one end, a degassing hole in the middle, and a discharge orifice at the other end, forming two chambers that are laterally interconnected and substantially cylindrical and parallel to each other. A chamber, two rotor shafts are fitted in the chamber in mesh with each other in parallel, and each rotor shaft has a part of a supply screw with a groove of a constant depth formed therein, and each rotor shaft has a blade cross section of a set of Banbari and substantially A first cross section having wings having a similar cross section and having a part twisted in a direction away from the rotation direction and a part twisted in the opposite direction; A movable wall that is movable in the radial direction provided in a part of the chamber, a constriction part that makes it possible to adjust the gap between the movable wall and the circular cross-sectional part, and a screw having the same shape as a part of the supply screw. a degassing part with open pores, a second crosstalk part having the same shape as the first crosstalk part, and a blade having a cross section substantially similar to that of a Banbari set and having no twist; and a discharge section with an open discharge orifice, and the length and torsion rate of the part twisted in opposite directions in the blades of each kneading section are the length and twist rate of the blade added to the material by the blade when the material is contained in the chamber. The average axial force applied is configured to be insufficient to force the material through the orifice, such that the overall axial travel of the material through the chamber is such that the average axial force exerted by the receiving means is insufficient to force the material through the orifice. In the twin-screw continuous kneading machine, which is determined by the accepted ratio, a movable wall and a circular cross-sectional part are used so that the pressure drop JP at the constriction part, which is calculated from the following formula, can be controlled within the range of 10 to 35 Kgf/i. A vented twin-screw continuous kneading machine characterized by setting the gap between the two screws, the length of the circular cross section, and the gap and height of the communicating section. However, η1: Apparent viscosity of the tip (, Kz f −s
ee/d) η2: Apparent viscosity of the communicating part (-
f-see/cd) Q8: Flow rate at the tip (cd/e
l-) Q,: Flow rate of communication part (cd/'MIC') L:
W is the circumferential length of the tip part CII+) W2 is the height of the communicating part) tl is the gap between the tip part (reserve) t2 is the gap of the continuous part (reserve) 2. The above pressure Decrease ΔP from 15 to 3 Q Kgf/cd
so that it can be controlled within the range of 11;1. L, t
2. The vented twin-screw continuous kneading machine according to claim 1, characterized in that W2 is set.