JPS6321381Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a twin-screw continuous kneader used for kneading polymeric materials such as synthetic resins.

Conventionally, this type of continuous two-shaft kneading machine generally has two rotatable rotors arranged in parallel in a chamber, each of which has a screw-shaped feed section and kneading blades with an oval cross-section, etc. in order from the material supply port side. A kneading section and a discharge section are provided,
The material to be kneaded is continuously supplied from the material supply port of the chamber, and is fed to the kneading section by the feed section, melted and kneaded in the kneading section, and then continuously discharged from the discharge port of the chamber. ing. In this structure, the kneading section usually has a feed section in which the kneading blades are twisted in the direction of forwarding the material to be kneaded, and a return wing section in which the kneading blades are twisted in the direction of returning the material. It is located in front over a certain area. By the way, when continuously kneading a liquid-added polymeric material, there are many processes in which the liquid component and the solid component are mixed and kneaded in advance in a batch type mixing or kneading machine, and then the mixture is fed to a continuous kneading machine. This is because in conventional continuous kneading machines, solids and liquids adhere and grow in the grooves of the screw section that directly supplies the solids and liquids to the kneading machine, which obstructs the conveying effect of the screw section and causes slippage in the kneading section. - This is because steady mixing and kneading of liquid components cannot be achieved.

This idea was made in view of the above points, and by using a two-stage twin-screw continuous kneader in the continuous mixing process of liquid-added polymeric material, solid components and liquid components are mixed together. The aim is to enable separate direct feeding and omit the pre-treatment equipment (pre-mixing kneader) of the continuous kneading machine, thereby significantly streamlining the continuous kneading process and saving energy. Make it.

In other words, liquid polymer materials include cases where polyvinyl chloride resin (generally referred to as PVC) and a plasticizer are used, cases where a thermoplastic resin and oil are used, cases where liquid rubber and fillers are used, etc. There are many different types.

Figure 1 shows a typical example of mixing PVC and plasticizer.
The kneading process is shown, but the content is that polyvinyl chloride resin M ₁ , additive M ₂ , and plasticizer M ₃ are weighed and mixed into hot mixer A, and after mixing, the temperature of the mixture is raised. Therefore, it is put into cooling mixer B and cooled down.

Furthermore, the cooled mixture is fed into the chamber from the hopper E of the continuous kneading machine D by a continuous metering machine C, and if necessary, pigments, fillers, or additives are fed into the chamber by a continuous metering machine F. It is designed so that it is kneaded by receiving shearing force.

Conventional mixing processes of this kind are widely used, but the processes for mixing and kneading solids and liquids generally include (1) wetting the surface of solid particles with liquid, and (2) pouring liquid while crushing the solid. (3) applying shear stress to melt or disperse the solid to homogenize it, but the roles of premixing and kneading are in the above (1) and (2). Correspondingly, the role of the conventional and commonly used continuous kneading machine corresponds to the above item (3). In addition, the degree of kneading is generally (shear stress τ)
It is related to x (practice time t).

However, in conventional processes, (a) in conventional continuous kneading machines, when solids and liquids are fed simultaneously, the conveyance capacity at the screw section is inhibited and slippage occurs at the kneading blades, and the kneading time is That is, since the residence time t is short, the above-mentioned items (1), (2), and (3) of the kneading process cannot be satisfied at once, so only the effect of item (3) can be achieved.

(b) Items (1) and (2) of the kneading process have poor productivity because they add a long kneading time t with a small shear stress τ.

(c) The kneaded material obtained from the hot mixer cannot be processed with a continuous weighing machine due to its high temperature, so it is passed through the cooling mixer again, or it is put into the mixer using a batch-type weighing machine and the process described in item (3) above is carried out. That there is a need.

(d) Due to the batch method, there is variation in the quality of the mixture. There are some inconveniences.

As mentioned above, the above-mentioned mixing and kneading process has the above-mentioned inconveniences, but the most likely reason for having to use the complicated and low-productivity process is that the above-mentioned (3) It exists in the function of a continuous kneading machine, which can only perform one function.

In order to solve the above problems, the present invention provides a continuous kneading machine with a common discharge orifice at one end, which is laterally interconnected to form two substantially cylindrical and mutually parallel chambers. a chamber, a two-shaft winged rotor located in the chamber, a material supply port configured to receive the material to be kneaded and stuff the material into the chamber under pressure at a position spaced apart from the discharge orifice; and the rotor. and means for rotating the rotors, each having a supply flight having a constant groove depth between the flights, and each having a cross-section substantially similar to a Banbury-type blade cross-section and having a rotor disposed far from the direction of rotation thereof. There are two kneading sections in the front and back in the axial direction each having blades having a part twisted in the opposite direction and a part twisted in the opposite direction, and a part twisted in the opposite direction in the blades of each kneading part. The length and torsion are such that when the material is contained within the chamber, the average axially directed force exerted by the vanes on the material is insufficient to force the material through the orifice. The rate at which a certain material is accepted by the receiving means is determined by the rate at which a certain material is accepted by the receiving means, and the feed section having the supply flight on the starting end side of both the rotors is made larger in diameter than the other section, and the feed section with the supply flight is The rotors mesh with each other, and between the front and rear kneading sections, a circular section provided on the rotor and a movable wall movable in the radial direction provided on a part of the chamber outside the rotor are connected to the movable wall and the circular section. This has been achieved by providing a constriction mechanism that allows adjustment of the gap between the liquid material supply port and the material supply port, and a structure in which a liquid material supply metering mechanism and a solid material supply metering mechanism are provided in a connected relationship above the material supply port. It is something.

The present invention will be explained below based on the embodiments shown in FIGS. 2 to 5.

In Figures 2 to 5, 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. Said chamber 1 is substantially cylindrical and forms two interconnected parallel chambers, both of which are provided in common with a discharge orifice 3.

Above the material supply 2, there is a liquid material measuring mechanism 12 that measures and supplies a predetermined amount of liquid material, and a solid material measuring mechanism 13 that measures and supplies a predetermined amount of solid material.
are separately provided in the material supply port 2 in a connected relationship. Reference numerals 4 and 4 denote two rotors arranged in parallel within the chamber 1, which are rotatably supported by the chamber 1 at their ends, and are normally rotated synchronously in opposite directions by means of a motor, reducer, gear, etc. (not shown). It is configured. These rotors 4, 4 each have, in order 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 kneading section 6, and a first kneading section 6, which will be described later. A circular cross section 71 that constitutes the aperture mechanism 7 together with a movable wall 72 of the chamber 1 and a second
A feed section 8, a second kneading section 9, and a discharge section 10 are provided.

The first feed section 5 is formed to have a larger diameter than the other sections, and the supply flight 51 of the feed section 5 is
The rotors 4, 4 are meshed with each other. In the figure, the feed flight 51 of the feed section 5 is shown as a three-thread screw, but it may also be a multi-thread or one-thread screw. Further, the chamber 1 that surrounds both rotors 4, 4 also conforms to the rotor shape, and naturally has a larger inner diameter at a portion corresponding to the first feed portion 5 than at other portions.

In the first kneading section 6, the rotor 4 has a non-circular cross-sectional shape, and kneading blades 61 protruding outward are formed suitable for providing shearing and stirring effects between the rotor 4 and the inner wall of the chamber 1 and between the rotors 4, 4. are doing.
In the illustrated example, the cross section has a shape in which the kneading blades 61 protrude on three sides, but a cross-sectional shape such as an oval shape in which the kneading blades protrude on two sides may also be adopted. Usually, from the starting end of the kneading section 6 to a suitable intermediate part, the kneading blades 61 are continuous with a twist of an appropriate lead angle in the direction away from the rotation direction, that is, in the direction of sending the material forward (hereinafter, this portion is referred to as the feeding blade portion 62),
From here to the end of the kneading section 6, it continues in the opposite direction, that is, in the direction in which the kneading blades 61 return the material, with a twist of an appropriate lead angle (hereinafter, this part will be referred to as the return blade section 63).
(called). In this case, the return wing portion 6
The length and torsion ratio of 3 are such that when the chamber contains material to be kneaded, the axial force applied to the material by the blades 61 is insufficient to force the material through the discharge orifice. , whereby the overall axial travel of the material to be kneaded through the chamber is determined by the rate at which the material is received by the receiving means. 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 71 is located at the terminal end of the first kneading section 6, and a movable wall 72 is provided in a part of the chamber 1 above and below the circular cross section 71.
The movable wall 72 and the circular cross section 71 constitute the aperture mechanism 7. The movable wall 7
The air cylinder 73 is movable in the radial direction while maintaining a sealed state with the other parts of the chamber 1, and the gap between the movable wall 72 and the circular section 71 changes as the movable wall 72 moves in the radial direction. It is operated by etc.

The second feed part 8 located in front of the circular cross-section part 71 has a screw shape like the first feed part 5, but in this part, the supply flights 81, 81 of both rotors 4, 4 do not have to mesh with each other. good. In addition, the second kneading section 9 is equipped with kneading blades 91 like the first kneading section 6, and has a pair of sending blades 92 and return blades 9.
It is composed of 3. The discharge section 10 is located near the end of the rotor 4 in front of the second kneading section 9, and is formed into a shape having straight wings or any other suitable shape.

In addition, the orifice 3 on the discharge side of the chamber 1 usually has one side wall 31 that can be opened and closed, and the opening amount of the orifice 3 is adjusted by opening and closing the side wall 31, thereby discharging the kneaded material. The resistance can be adjusted.

Further, if necessary, the chamber 1 may be provided with a vent hole 11 to enable vacuum degassing of volatile components contained in the material being kneaded. It should be provided at a position between the movable wall 72 of No. 7 and the material discharge port, and it is particularly desirable to provide it near a location corresponding to the second feed section 8 near the movable wall 72.

The embodiments shown in FIGS. 2 to 5 have the above-mentioned configuration, but the second feed section 8 of the embodiment may be omitted (not shown).

Furthermore, even in this case, it is also possible to provide a vent hole at an appropriate location in front of the movable wall 72 in the chamber 1.

In addition, in the embodiment, the feeding blade portions 62, 92 of the kneading blade
An example is given in which the return wings 63 and 93 are continuous, but these two wings do not necessarily need to be continuous,
It may be an intermittent blade in which the phase of the blade is shifted at the joint between the sending blade and the return blade.

Next, the operation of the kneader of the present invention will be explained.

A predetermined amount of liquid component material is measured by a liquid material supply metering mechanism 12, and a predetermined amount of solid component material is measured by a solid material supply metering mechanism 13, and each material is separately placed at one end of the chamber 1 of the kneader. The material to be kneaded is continuously and quantitatively supplied to the material supply port 2, and the supplied material is first sent forward in the axial direction by the feed portion 5 on the starting end side of the rotor 4. In this case, in the machine of the present invention, the feed portion 5 is made large in diameter, and the feed flight 51 is connected to both rotors 4,
4. By interlocking with each other, the mixture of the solid component and the liquid component can be conveyed to the first kneading section 6 without adhering to and growing in the screw groove.

The material to be kneaded sent from the feed section 5 is
In the first kneading section 6, the surface of the solid particles is wetted with the liquid, and the solid particles are impregnated with the liquid while being pulverized, and then exothermic softening and melting is started under the action of shearing.

That is, part of the role of the hot mixer and continuous kneader in the conventional process is performed in the first kneading section. Note that the cooling mixer in the conventional continuous kneading process is used to facilitate the handling of the materials to be kneaded after the hot mixer.
The process according to the invention does not require the role of a cooling mixer. Then, it passes through the diaphragm mechanism 7,
It is sent to the second kneading section 9 through the second feed section 8 or directly to the second kneading section 9.

In conventional continuous kneading machines, slips occur when solids and liquids enter the kneading blades, and the so-called surging phenomenon occurs in which the melting start position changes in the axial direction due to shear. The surging phenomenon is prevented by providing the throttle mechanism 7 between the kneading section and the second kneading section.

This throttling mechanism 7 adjusts the gap between the movable wall 72 and the circular section 71 of the rotor 4 in advance by moving the movable wall 72 in the axial direction, and narrows the flow path as appropriate. It functions to prevent pressure fluctuations in the first kneading section and to appropriately control the magnitude of the material pressure in the first kneading section 6 and the second kneading section 9. In addition, in connection with this pressure adjustment action, a temperature increase due to shear heat generation is also controlled, and as a result, as shown by curve B in FIG. Average the temperature across the product to avoid rapid temperature rises that would cause quality deterioration. Furthermore, due to this flow channel restricting action, the first
This prevents uneven kneading due to the short pass of the material, which is hardly subjected to shearing action in the kneading section. Furthermore, by material sealing with molten material at this part and the orifice 3 on the discharge end side, the airtightness within the chamber 1 is maintained between them, making it possible to perform vacuum degassing as described below. .

When feeding the material to the second kneading section via this squeezing mechanism 7, if you particularly want to increase the feed force, a structure in which the second feed section 8 is provided as shown in the embodiment may be adopted, but the rotor 4 Feed section 5 on the starting end side
Sufficient feeding force can be obtained by only using the second feed section 8, so if emphasis is placed on improving the degree of kneading, the second feed section 8 may be omitted (not shown). or second kneading section 19
If a vent hole 11 is provided at a position corresponding to the material, etc., the volatile components contained in the material being kneaded will be removed by connecting this to a vacuum pump (not shown) and performing vacuum degassing. This prevents air bubbles from remaining in the product. In this case, the installation location of the throttle mechanism 7 and the discharge side orifice 3 are each material sealed, and the supply flight of the second feed section 8 or the kneading blade of the second kneading section 9 is used to feed the material. Vacuum degassing becomes possible by setting an appropriate inclination angle to prevent material from filling in such areas. Furthermore, if necessary, by providing an addition port (not shown) in the chamber 1 at a location corresponding to the second feed section 8, etc., materials that are easily damaged or accelerate wear of the machine, such as glass fibers, can be removed. You can also replenish the supply with ゝ.

The second kneading section 9 melts the resin or disperses solid components by the shear stress generated in the sickle-shaped space between the rotor and the chamber, and homogenizes the kneaded material. It acts to uniformly mix the materials added by etc.

The discharge orifice 3 on the discharge end side of the chamber 1 can change the discharge resistance of the molten material by adjusting the opening amount, thereby making it possible to adjust the degree of kneading, but the structure of the orifice 3 is similar to the illustrated embodiment. However, for example, a tiltable movable body may be provided in the flow path to adjust the discharge resistance. Furthermore, if the kneaded material is to be granulated, an extruder may be connected to the discharge side of the kneader for pelletizing, or a means for extrusion and granulation via a gear pump may be attached as appropriate. ,in this case,
Since a sufficient degree of kneading can be obtained with the kneader of the present invention, there is no need to use an extruder to compensate for the lack of kneading, and it is sufficient to employ a compact gear pump.

〔Example〕

Chamber inner diameter 54mmφ L/D 10 Rotor rotation speed 500rpm Processing amount 60Kg/h Discharged resin temperature 165℃ Material: PVC degree of polymerization = 1100 100 parts Plasticizer DOP 40 parts Pigment Additives 7 parts As a result of testing under the above conditions, A film was made from the kneaded product using a roll, and the skin of the film was found to be of the same quality as that of a conventional product.

FIG. 6 shows the material temperature distribution (actually measured values) in the example in comparison with the conventional machine. Since the first kneading section includes the crushing and mixing process of solids, there is insufficient contact between the material to be kneaded and the chamber wall surface, making cooling difficult. Because it is transported, heat transfer is good on the chamber wall or rotor surface. Therefore, even if the machine length is increased, the temperature of one material can be suppressed to a predetermined value.

That is, the cooling efficiency can be made extremely high. By suppressing the material temperature to a predetermined value, τ=
Since the viscosity η of ηγ can be kept at a large value, a large shear stress τ can be applied to the material, so the kneading quality is improved without having to knead for a long time as in conventional hot mixer cooling mixers.

As described above, the two-shaft continuous kneading machine of the present invention has a kneading section at two locations in the axial direction of each of the two rotors to increase L/D, compared to the conventional kneading section which had a kneading section at only one location. Even for materials to be kneaded which were difficult to apply due to the lack of kneading time, the kneading time is increased and a sufficient degree of kneading can be obtained.
The feed section at the starting end of the rotor has a large diameter, and its feeding flights mesh with the rotor, so even if solids and liquids are simultaneously supplied to the kneader, a high material conveying force can be obtained, resulting in a decrease in processing capacity. Never. Furthermore, between the front and rear kneading sections, there is a throttling mechanism that can adjust the gap between the circular section provided on the rotor and a radially movable movable wall provided on a part of the chamber. With this mechanism, pressure fluctuations can be prevented to optimize the pressure of the materials to be kneaded in the chamber, and the temperature of the materials in the chamber can be averaged to avoid rapid temperature increases that would cause quality deterioration. Uneven kneading caused by short passes of the materials can be eliminated, and the quality of the kneaded product can be significantly improved by their synergistic effect. Moreover, the structure of the throttling mechanism is simple and operation is very easy, and the material seal between such parts and the discharge end prevents volatile components from being removed by vacuum degassing by providing a vent hole between them. Furthermore, liquid and solid materials can be metered and supplied 12 and 1 in a connected relationship above the material supply port 2.
3 to directly supply the liquid material and solid material separately, eliminating the need for a pretreatment process and equipment for the materials to be kneaded, which has the effect of streamlining the kneading/mixing process and saving energy. ,
This is an industrially extremely useful invention for mixing and kneading this type of liquid polymeric material.

[Brief explanation of drawings]

Fig. 1 is a conceptual process diagram showing the process of mixing and kneading liquid polymer materials, Figs. 2 to 5 show an embodiment of the biaxial continuous kneading machine of the present invention, and Fig. 3 is an enlarged sectional view taken along the - line in Fig. 2, Fig. 4 is an enlarged sectional view taken along the - line in Fig. 2, and Fig. 5 is an enlarged sectional view taken along the - line in Fig. 2. FIG. 6, an enlarged cross-sectional view along the line, is a graph showing a pattern of temperature changes accompanying the movement of materials to be kneaded in the chamber in the kneader of the present invention in comparison with a conventional case. 1...Chamber, 2...Material supply port, 3...
Orifice for material discharge, 4... Rotor, 5... Feed section, 6... First kneading section, 7... Squeezing mechanism,
71...Circular cross section, 72...Movable wall, 9...Second kneading section, 12...Measuring mechanism for liquid material supply, 1
3...Measuring mechanism for solid material supply.

Claims (1)

[Claims for Utility Model Registration] 1. 2 substantially cylindrical and mutually parallel interconnected laterally having a common discharge orifice at one end.
a chamber forming two chambers, a two-shaft winged rotor located in the chamber, and a material supply configured to receive the material to be kneaded and stuff the material into the chamber under pressure at a position spaced apart from the discharge orifice. a mouth, and means for rotating the rotors, each of the rotors having a feed flight with a constant groove depth between the flights, and each having a cross-section substantially similar to a Banbury-type airfoil cross-section; Two kneading sections in the front and back in the axial direction each having wings having a part twisted in a direction away from the rotation direction and a part twisted in the opposite direction are provided, and the kneading parts are arranged in two places in the front and back in the axial direction, and the kneading parts are arranged in two places in the front and back in the axial direction, each having a part twisted in a direction away from the rotation direction and a part twisted in the opposite direction. The length of the twisted portion and the torsion rate are such that the average axially directed force exerted on the material by the wings when the material is contained in the chamber forces the material through the orifice. wherein the overall axial travel of the material through the chamber is determined by the rate at which the material is received by the receiving means; The feed portion with the feed flights on the starting end side of both rotors is made larger in diameter than the other portions, and the feed flights are meshed with both rotors, and a circular feed portion provided on the rotor is provided between the front and rear kneading portions. A diaphragm mechanism is provided in which the gap between the movable wall and the circular cross-sectional part can be adjusted by a cross-sectional part and a movable wall movable in the radial direction provided in a part of the chamber outside the cross-sectional part, and the upper part of the material supply port. A two-shaft continuous kneading machine characterized in that a liquid material supply metering mechanism and a solid material supply metering mechanism are provided in a continuous relationship to enable continuous and stable mixing and kneading of solid materials and liquid materials. 2. The continuous kneading machine according to claim 1, which is a registered utility model, characterized in that the chamber is provided with an opening having a function of degassing and supplying a third component downstream of the throttle mechanism.