JPH10138234A - Biaxial continuous kneading machine and its material kneading method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a kneading output from decreasing by enhancing the frictional force of a material to be kneaded on the inner face of a chamber in the early stage of kneading process, when kneading the fine powder material to be kneaded using a biaxial continuous kneading machine. SOLUTION: This method for kneading a material is to feed a fine powder material to be kneaded to the downstream side of paired rotors 4 with the help of a feed part 18 formed on the upstream of said rotors 4 introduced, in freely rotating manner, through a chamber 2. In addition, the material to be kneaded is melted by kneading under the self-generated heat effects due to shearing force induced in the material, by a kneading part 19 with a feed blade part 19A and a returning blade part 19B formed on the downstream side of the feed part 18 for the rotors 4. In this case, the material is kneaded while heating a part corresponding to the feed blade part 19A of the chamber 2 beyond the melt point of a polymer content of the material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biaxial continuous kneader for kneading a polymer resin material such as plastic and a method for kneading the same.

[0002]

2. Description of the Related Art As a twin-screw continuous kneader of this type, a chamber having a supply port for a material to be kneaded at an upstream end and a discharge port at a downstream end, and both ends in the axial direction in the chamber. A pair of rotors inserted in a rotatably supported state, and a feed section for feeding the kneaded material to the upstream side on an outer peripheral portion of the rotor; and a feed portion for feeding the kneaded material to the upstream. It is known that a kneading portion having a feed wing portion and a return wing portion to be melted by self-heating due to shearing is formed in order from the upstream side (for example, see Japanese Patent Publication No. 58-50533).

In such a twin-screw continuous kneader, the material to be kneaded self-heats due to a large shear stress generated when the material passes between the tip of the kneading blade and the inner surface of the chamber, and the material is exclusively heated by the self-heating. It is considered that the maximum kneading effect can be obtained with the minimum material heating energy for melting, and in particular, the finely kneaded material (fine powder filler compound) having a large content of the inorganic filler,
Suitable for kneading materials to be kneaded which requires a high degree of kneading.

[0004]

Among the kneading materials which can be kneaded by the above-mentioned twin-screw continuous kneader, particularly when kneading a fine powder filler compound containing a large amount of fine filler such as talc, the bulk specific gravity is extremely high. Small and contains a lot of air inside, the air mixed together in the chamber at the time of material supply flows back to the upstream side and reduces the carrying capacity of the rotor's feed section, thereby reducing the production volume There is a problem of doing.

[0005] In addition, the fine powder filler compound has a small coefficient of friction with the inner surface of the chamber due to its fineness and is slippery. Therefore, it is difficult to convey it by the feed portion and it is hard to generate self-heating in the kneading portion. Is causing the decrease. In view of such circumstances, the present invention reduces the production volume by improving the frictional force of the same material with respect to the inner surface of the chamber in the initial stage of kneading when kneading the finely kneaded material with the twin-screw continuous kneader. The purpose is to prevent.

[0006]

According to the present invention, the following technical measures have been taken in order to achieve the above object. That is,
According to the present invention, a kneaded material in the form of fine powder is fed downstream by a feed portion formed on an upstream side of a pair of rotors rotatably inserted into a chamber, and formed on a downstream side from a feed portion of the rotor. When the material to be kneaded is kneaded and melted by self-heating due to the shear stress generated therein in the kneading section having the fed wing portion and the return wing portion, a portion corresponding to the feeding wing portion of the chamber is mixed with the material to be kneaded. The material to be kneaded is kneaded while heating to above the melting point of the polymer component.

In this case, the polymer component of the material to be kneaded melted at the portion corresponding to the feed blade portion adheres to the inner surface of the chamber, and increases the frictional force between the material to be kneaded and the inner surface of the chamber at that portion. Further, since the feed wing portion of the rotor has a material transfer function, the frictional force against the inner surface of the chamber corresponding to the feed wing portion is increased, whereby the transfer function to the downstream side is secured, and a decrease in the production amount is prevented. You.

[0008] On the other hand, by heating the portion corresponding to the feed wing portion in this manner, the transfer capacity at the initial stage of kneading is ensured. Excessive heating of the material may cause deterioration of the product. Therefore, it is preferable to knead the material to be kneaded while cooling a portion downstream of the portion corresponding to the feed blade portion of the chamber.

In a two-stage type apparatus having a gate device in the middle of the chamber, this cooling can be performed downstream of the gate device (see FIG. 1), and a one-stage type device without the gate device is provided. Then, it can be performed in a range after the return wing portion of the chamber (see FIG. 6). In the case where the chamber is heated for the above-described purpose, if only the portion corresponding to the feed wing portion among the portions corresponding to the kneading portion of the chamber is heated, excessive heat in the return wing portion immediately downstream thereof is provided. Is prevented, and the deterioration of the material can be more reliably prevented.

The present invention is not limited to a method of heating a chamber, but also a method of injecting a molten resin having the same material as a polymer component of a material to be kneaded into a portion corresponding to a feed blade portion in the chamber from outside the chamber. Also provide. Also in this case, since the molten resin injected from the outside of the chamber adheres to the inner surface of the chamber corresponding to the feed wing portion, the same operation as in the above case of heating the chamber to generate the molten resin can be obtained.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 show a first embodiment of the present invention. In FIG. 1, a twin-screw continuous kneader 1 according to this embodiment includes a chamber 2 as an apparatus main body. In the chamber 2, a double kneading chamber 3 having a substantially cylindrical shape in a longitudinal direction has a substantially eyeglass shape in cross section. Are formed so as to communicate with each other.

In each kneading chamber 3 of the chamber 2, the material to be kneaded is fed from the upstream side (the right side in FIG. 1) of the chamber 2 to the downstream side (the left side in FIG. 1). A pair of left and right rotors 4 and 4 for kneading and melting are inserted parallel to each other and rotatably. Each rotor 4,
Both ends in the axial direction of 4 are rotatably supported via bearings (not shown) provided at the upstream and downstream ends outside the chamber 2.

A driving device 8 for the rotor 4 is connected to a downstream end of the chamber 2. The driving device 8 includes a casing 9 tandemly connected to a downstream end of the chamber 2.
A pair of front and rear bearings for rotatably supporting the drive shafts 10 of the rotors 4, 4 inserted into the casing 9, and a drive gear fixed to an intermediate portion of the drive shaft 10 in the axial direction; It has.

The drive shaft 10 of one of the pair of rotors 4, 4 protrudes further upstream of the casing 9, and its protruding end is connected to the motor 12. The drive gears of the rotors 4 and 4 are directly meshed with each other. Therefore, when one of the rotors 4 is driven to rotate by the motor 12, the other rotor 4 rotates in a different direction.

A supply port 1 for supplying a powdery material to be kneaded to the kneading chamber 3 is provided on the upper surface side of the upstream end of the chamber 2.
The hopper 11 is connected to the supply port 13. A vent hole 1 for degassing gas and water vapor generated in the chamber 2 from the kneading chamber 3 is provided immediately downstream of a gate device 17 described later in an intermediate portion of the chamber 2.
4 are formed.

A discharge port 1 for discharging the kneaded material melted by self-heating due to the shearing force of the rotor 2 to the outside of the chamber 2 is provided on the lower surface side of the downstream end of the chamber 2.
5 is provided, and the discharge port 15 adopts a downward discharge type that opens downward. Further, a gate device 17 is provided in the middle of the chamber 2 to adjust the flow resistance of the material to be kneaded by moving the pair of upper and lower gate plates 16 closer to or away from the outer periphery of the rotor 4 from the radial outside. The chamber 2 is divided by the gate device 17 into an upstream segment 2A and a downstream segment 2B. The kneading chamber 3 in the chamber 2 is divided into two on the upstream side and the downstream side of the gate device 17. Kneading stage 3
A and 3B.

Of these, the powdery material to be kneaded from the supply port 13 is fed to the outer peripheral surface of the rotor 4 inserted in the first stage 3A on the upstream side of the gate device 17 in order from the upstream side. A first feed section 18 composed of a screw blade for feeding and a first kneading section 19 for kneading and melting the powdery material to be kneaded by applying a strong shearing force to the material are each formed.

The first kneading portion 19 has a feed blade portion 19A twisted in a direction for pushing out the material to be kneaded downstream by the rotation of the rotor 4, and a return twisted in a direction to push back the material to be kneaded upstream by the rotation. And wings 19B. On the other hand,
On the outer peripheral surface of the rotor 4 inserted into the second stage 3B on the downstream side of the gate device 17, screw blades forcibly conveying the material melted in the kneading unit 19 to the discharge port 15 in order from the upstream side. And a second kneading section 21 for kneading the material extruded from the feed section 20 again. In the present embodiment, the second kneading unit 21 also includes
A feed wing 21A and a return wing 21B are employed.

A flapper orifice 22 is provided below the outlet 15 as a means for adjusting the discharge amount. However, a gear pump may be connected to the discharge port 15 via a connecting pipe, and the discharge amount may be adjusted by the gear pump. As shown in FIGS. 1 and 2, inside each of the segments 2A and 2B of the chamber 2, heat medium passages 23A and 23B for heating or cooling them are formed. The heat medium passages 23A, 23B are connected to the segments 2A,
A portion outside the kneading chamber 3 inside the 2B is formed by hollowing out a portion in the axial direction of the rotor, and a large number are arranged at positions surrounding the kneading chamber 3.

Of the segments 2A and 2B of the chamber 2, the segment 2A on the upstream side
Is connected to a heating device 24 for heating the material to a temperature equal to or higher than the melting point of the polymer component of the kneaded material. The heating device 24 has a function of supplying a heating oil to the heating medium passage 23A and collecting the heating oil from the passage 23A, and a function of heating the collected heating oil to a set temperature.

On the other hand, a cooling device for cooling the segment 2B to the extent that the molten resin in the segment 2B is not thermally degraded is connected to the downstream segment 2B. The cooling device 25 has a function of supplying cooling water to the heat medium passage 23B and collecting the cooling water from the passage 23B, and a function of cooling the collected cooling water to a set temperature. Also, each upstream heat medium passage 23A is connected to the first feed portion 18.
From the downstream end to the vicinity of the gate device 17, and the downstream heat medium passage 23 </ b> B reaches the range from immediately downstream of the vent port 14 to the discharge port 15.

[0022]

Next, using the twin-screw continuous kneader 1 (LCM50, manufactured by Kobe Steel, Ltd., chamber inner diameter: 50 mm), the set temperature of the heating device 24 was changed variously to actually form the fine powder filler compound. Test kneading was conducted to investigate the effect of the heating temperature of the upstream segment 2A on the production amount. FIG. 3 is a graph obtained based on the experimental results.

In FIG. 3, the horizontal axis represents the heating temperature of the segment 2A on the upstream side, and the vertical axis represents the limit rotor speed required to secure a certain amount of production at that temperature setting (the hopper is used below this speed). The material accumulates at the bottom.) In this experiment, the constant output was 40
(Kg / h). The following three types of resins were mixed in this experiment. ●-● line polypropylene (MFR = 3) 20wt% talc (2.8μ) 80wt% ○-○ line polypropylene (MFR = 40) 20wt% talc (2.8μ) 80wt% ■-■ line high density polyethylene (MI = 0.05) 20 wt% talc (3.0 μ) 80 wt% In this experiment, in any case, by cooling the downstream segment 2B with water, the temperature in the second stage was kept at a constant temperature so as not to deteriorate. Held. The melting point of polypropylene is about 160 ° C, and the melting point of high-density polyethylene is about 130 ° C.

As shown in FIG. 3, in any of the above three types of blends, the line is lowered to the right,
When the upstream segment 2A is heated, the limit rotor rotation speed decreases (that is, a desired production amount can be obtained with a small rotation speed), and a decrease in the production amount can be prevented. In particular, when a large amount of an inorganic filler is mixed with polypropylene having a high melting point and a resin that is difficult to melt (●-●
Line and ○-○ line), the melting point (about 1
When the line is heated at a temperature higher than 60 ° C., the degree of the line falling to the right is extremely large, and the segment 3A
Heating greatly affects the increase in production.

The above experiment was carried out using a test device (by
The LCM50 manufactured by Kobe Steel, Ltd. was used. However, in an actual operation device (LCM230 manufactured by Kobe Steel, LCM230, chamber inner diameter: 230 mm), the kneading of the fine powder filler compound heats the upstream segment 2A and lowers the downstream segment. It was confirmed that, when the segment 2B was cooled, a kneaded material of good quality could be obtained without reducing the production amount.

FIG. 4 shows a modification of the heating range of the upstream segment 2A. That is, in this case, the upstream segment 2A includes the feed wing portion 19A and the return wing portion 19B.
Is divided into a first half portion 28 and a second half portion 29 at a boundary point (apex) 27 of the heat medium passage 2 only in the first half portion 29.
3A, the kneading unit 1 in the chamber 2 is provided.
9, only the portion corresponding to the feed wing portion 19A is heated.

In this case, the material heated at the position corresponding to the feed wing portion 19A can be prevented from excessively rising in the return wing portion 19B immediately downstream thereof, and the material is deteriorated at the stage of the first stage 3A. Can be prevented from occurring. FIG. 5 shows a second embodiment of the present invention. In this embodiment, an injection device 30 for injecting a molten resin having the same material as the polymer component of the material to be kneaded into the portion corresponding to the feed wing portion 19A in the chamber 2 from the outside of the chamber 2 is provided.

In this case, the injection device 30 comprises an extrusion cylinder 31
A single-screw extruder in which a screw 31 is inserted through the inside of the device is adopted. The discharge portion of this extruder is connected to an inlet 33 provided on the lower surface side of the upstream segment 3A, and the resin extruded from the single-screw extruder receives the resin from the inlet 33 corresponding to the feed blade portion 19A in the chamber 2. It is to be injected into the location.

Also in this embodiment, since the molten resin injected from the outside of the chamber 2 adheres to the inner surface of the chamber 2 corresponding to the feed wing portion 19A, the molten resin is generated by heating the chamber 2 according to the first embodiment. The same operation as in the case is obtained. However, in this embodiment, a large-scale addition of the injection device 30 such as a single-screw extruder is required, and equipment cost is increased. Therefore, the first embodiment which does not have such a disadvantage in this point is superior.

FIG. 6 shows a third embodiment of the present invention. In this embodiment, the present invention is applied to a gate device 17.
One-kneading type twin-screw continuous kneader without
(KCM and NCM series of Kobe Steel, Ltd.). Therefore, the first embodiment (FIG. 1) and the present embodiment (FIG. 6) are different in that the kneading chamber 3 is divided into two stages by the gate device 17 in the former, but is one stage in the latter. I do.

In such a one-stage type apparatus, the temperature rise in the chamber 2 is likely to lead to the deterioration of the resin. Therefore, the chamber 2 is divided into three segments 35, 36, and 37 to correspond to the feed blade 19A of the kneading section 19. Intermediate segment 3
6 is connected to the heating device 24, and the cooling device 25 is connected to a downstream segment 37 downstream of the heating device 24.

It should be noted that the injection device 30 can be connected to the intermediate segment 36 as in the case of FIG. Although the embodiments of the present invention have been described above, these embodiments are illustrative and not restrictive. The scope of the present invention is determined by the appended claims, and all embodiments that come within the meaning are included in the scope of the present invention.

For example, the heating device 24 is provided in the chamber 2
It can also be configured by winding an electric heater around the outer periphery of the heater. In FIG. 1, the rotor 4 in the second stage 3B
Is provided with both the feed section 20 and the kneading section 21. However, the present invention is directed to a biaxial continuous type in which only one of these sections 20 and 21 is provided in the portion of the rotor 4 in the second stage 3B. It can also be used for the kneading machine 1.

[0034]

As described above, according to the present invention,
Since the frictional force of the material to be kneaded against the inner surface of the chamber in the initial stage of kneading is improved, it is possible to prevent a decrease in the production amount when kneading the finely kneaded material such as a fine powder filler compound.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing an entire structure of a twin-screw continuous kneader according to a first embodiment.

FIG. 2 is a cross-sectional view of the continuous kneader.

FIG. 3 is a graph showing a relationship between a heating temperature (resin temperature) of a chamber and a limit rotor speed.

FIG. 4 is a side sectional view showing a modification of the heating range of the upstream segment.

FIG. 5 is a side sectional view of an upstream portion of a twin-screw continuous kneader according to a second embodiment.

FIG. 6 is a side sectional view showing the entire structure of a twin-screw continuous kneader according to a third embodiment.

[Explanation of symbols]

 Reference Signs List 1 twin-screw continuous kneader 2 chamber 4 rotor 13 supply port 15 discharge port 18 (first) feed section 19 (second) kneading section 19A feed wing section 19B return wing section 24 heating device 25 cooling device 30 injection device

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Koji Ueda 2-3-1, Shinhama, Arai-cho, Takasago-shi, Hyogo Inside Kobe Steel, Ltd. Takasago Works

Claims (7)

[Claims] A feed portion (18) formed on an upstream side of a pair of rotors (4) rotatably inserted into a chamber (2) feeds a finely powdered material to be kneaded to a downstream side. The kneading section (19) having a feed wing section (19A) and a return wing section (19B) formed downstream of the feed section (18) of the rotor (4) shears the material to be kneaded therein. In a material kneading method using a twin-screw continuous kneader configured to perform kneading and melting by self-heating due to stress, a portion corresponding to a feed blade portion (19A) of the chamber (2) is set to a temperature higher than a melting point of a polymer component of the material to be kneaded. A material kneading method using a biaxial continuous kneader, wherein the material to be kneaded is kneaded while heating. 2. The kneading machine according to claim 1, wherein the material to be kneaded is kneaded while cooling a portion downstream of a portion corresponding to the feed blade portion (19A) of the chamber (2). Kneading method. 3. A fine powdery material to be kneaded is fed downstream by a feed portion (18) formed upstream of a pair of rotors (4) rotatably inserted into the chamber (2). The kneading section (19) having a feed wing section (19A) and a return wing section (19B) formed downstream of the feed section (18) of the rotor (4) shears the material to be kneaded therein. In a material kneading method using a twin-screw continuous kneader configured to perform kneading and melting by self-heating due to stress, a portion corresponding to a feed blade portion (19A) in the chamber (2) has the same composition as the polymer component of the material to be kneaded. While injecting the molten resin of the material from the outside of the chamber (2),
A material kneading method using a biaxial continuous kneader, wherein the material to be kneaded is kneaded. 4. A supply port (1) for a material to be kneaded is provided at an upstream end.
3) and a chamber (2) having a discharge port (15) at a downstream end thereof, and a pair of rotors (2) inserted into the chamber (2) with both axial ends being rotatably supported. 4), a feed portion (18) for feeding the material to be kneaded upstream, and a self-heating caused by shearing the fed material to be kneaded on the outer peripheral portion of the rotor (4). Feed wing section (19)
Kneading section (19) having A) and return wing section (19B)
In a twin-screw continuous kneader formed in order from the upstream side, a heating device (24) for heating a portion corresponding to the feed blade portion of the chamber (2) to a temperature higher than the melting point of the polymer component of the kneaded material. ) Is provided. 5. The twin-screw continuous kneader according to claim 4, further comprising a cooling device (25) for cooling a portion of the chamber (2) downstream of a portion corresponding to the feed blade portion (19A). . 6. The twin-screw continuous kneader according to claim 4, wherein the heating device (24) heats only a portion corresponding to the feed blade portion (19A) of the chamber (2). 7. A supply port (1) for a material to be kneaded is provided at an upstream end.
3) and a chamber (2) having a discharge port (15) at a downstream end thereof, and a pair of rotors (2) inserted into the chamber (2) with both axial ends being rotatably supported. And a feed portion (1) for feeding the material to be kneaded upstream to the outer peripheral portion of the rotor (4).
9A) and a feed wing (19A) for melting the fed material to be kneaded by self-heating accompanying shearing.
In the twin-screw continuous kneader in which a kneading section (19) having a wing section (19B) and a return wing section (19B) are formed in order from the upstream side, the portion corresponding to the feed wing section (19A) of the chamber (2) is A twin-screw continuous kneader provided with an injection device (30) for injecting a molten resin having the same material as the polymer component of the material to be kneaded from outside the chamber (2).