JPH0224204B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a resin extrusion molding apparatus.

A resin extrusion molding device consists of an extruder with a die attached to the tip. Many extruders have a mechanism in which a screw is attached to a barrel and the screw rotates to continuously extrude. It was thought that an extruder equipped with a plunger or gear pump could be used instead of a screw, but in reality, an extruder with a screw is the only machine used to make large molded objects such as pipes or plates. used.

It has not generally been the case that one extruder is equipped with a screw and a plunger or gear pump at the same time. This is because the screw alone can heat and knead the resin sufficiently to bring it into a state suitable for extrusion. In particular, by changing the length or structure of screws, it was possible to plasticize most resins. However, when extrusion molding a foam, it has been proposed to add a foaming agent in the extruder and then add a gear pump to the extruder in order to uniformly stir and propel the foaming agent-containing resin. It is described in Special Publication No. 48-42460.
According to the method described in this publication, when a gear pump is used in combination, it becomes easy to uniformly contain the foaming agent, and a good foam can be obtained. However, these foams are limited to those with a small cross section, and when attempting to obtain a foam with a large cross section, the foaming becomes non-uniform.

Furthermore, when attempting to obtain a foamed sheet with a thickness of approximately 3 m/m using the Circular Die, there was a drawback in that a broken shape with a height difference of approximately 1.5 mm was produced on the surface.

The inventor considered the cause of the drawbacks in the method described in Japanese Patent Publication No. 48-42460 as follows. That is, in this method, after mixing the blowing agent,
Because the resin is simply stirred with a gear pump,
We believe that this is because the resin in the center and periphery of the resin passage cannot be maintained at a uniform temperature.

On the other hand, it is already known to use static mixers to uniformly mix resins. Furthermore, in order to better mix the resin extruded from the extruder, it has already been proposed to attach a static mixer to the tip of the screw type extruder. However, a static mixer is constructed by inserting a passage dividing body into a short cylinder, and the passage dividing body has a large number of divided passages therein. It is of a structure in which adjacent passages are oriented diagonally relative to each other, and adjacent passages include passages with different traveling directions. Therefore, the resin flowing through the static mixer is
Not only are they mixed as they are guided by the passage divider and proceed diagonally and irregularly inside the cylinder, but they also repeat gathering and division while moving from passage divider to passage divider, thereby causing Mix thoroughly. At the same time, the resin flow is subjected to great resistance. Therefore, the addition of a static mixer requires a significant increase in extrusion pressure. Therefore, it was considered undesirable to add a static mixer because it would unnecessarily reduce the amount of extrusion.

The inventor discovered that when a gear pump is used in conjunction with a static mixer, the gear pump compensates for the reduction in throughput caused by the static mixer, and also facilitates agitation.
In addition, it has been found that the heat generated by stirring is small and is sufficient to bring the resin into a suitable extrusion state. This invention was made based on such knowledge.

The present invention relates to a resin extrusion molding apparatus characterized in that a gear pump and a static mixer are arranged in series in a resin passage between an extruder and a die.

The apparatus of the present invention will be explained with reference to the drawings as follows. 1 and 2 are partially cut away longitudinal sectional views of a device according to the invention, respectively. In these figures, 1 is an extruder and 2
is a static mixer, 3 is a gear pump,
4 is the cap. The extruder 1 includes a barrel 11 and a screw 12 rotatably attached thereto.
The static mixer 2 is constructed by inserting a passage dividing body 22 into a short cylinder 21, and the passage dividing body 22 is composed of a large number of small plates 23 and 24 crossed in different directions. A divided passageway is provided between each of the plates 23 and 24. The divided passages have their traveling directions directed obliquely to the axis of the cylinder 21, and adjacent passages have different traveling directions. Gear pump 3 is
Gears 32 and 33 that mesh with each other are rotatably attached to a housing 31. Base 4
In this example, an inner mold 42 is fixed within an outer mold 41, and a cylindrical resin passage is provided therebetween.

When the apparatus shown in FIG. 1 is used, the resin heated and uniformly kneaded in the extruder 1 is transferred to the static mixer 2.
Then, it passes through the gear pump 3 and is extruded from the mouthpiece 4. In this case, in the static mixer 2, a part of the resin is made to advance diagonally downward along the small plate 23, and after colliding with the cylinder 21,
It is made to advance obliquely upward along the small plate 24.
Further, another portion of the resin is made to advance diagonally upward along the small plate 24, and after colliding with the cylinder 21, is made to proceed diagonally downward along the small plate 23. In this way, the intersecting small plates 23 and 24 cause the resin to travel diagonally downward and diagonally upward, respectively, so that the resin is thoroughly mixed throughout.

While traveling along the platelets 23 and 24 in the static mixer 2, the resin is resisted by the platelets 23 and 24. Therefore, when the resin leaves the static mixer 2, the extrusion pressure is low, so
Extrusion rate decreases. Therefore, the resin is introduced into the gear pump 3, and the necessary pressure is applied therein by the gears 32 and 33 to increase the extrusion pressure and increase the extrusion amount. At the same time, the resin is kneaded between the gears 32 and 33 to make it suitable for extrusion. Thereafter, the resin enters the cap 4 and is molded into a cylindrical shape to form a molded body.

It is particularly suitable for molding thick extruded foam boats.

When operating the apparatus shown in Fig. 2, the resin heated and uniformly kneaded in the extruder 1 first enters the gear pump 3, where it is kneaded and the extrusion pressure is increased. stationary mixer 2
After that, it is pushed out from the cap 4. Therefore, in the case of Fig. 2, the resin is first reinforced with extrusion pressure and then mixed, but overall the pressure reinforcement and mixing are carried out to the necessary extent. , is the same as the case using the apparatus shown in FIG.

However, when the extrusion pressure of the extrusion screw is low, the apparatus shown in FIG. 2 is suitable for increasing the extrusion rate and is more suitable for solving the uneven thickness of the foam sheet obtained from the circular die.

As the passage dividing body 22 used in the static mixer 2 in the apparatus of this invention, one as shown in FIG. 3 can be used. In FIG. 3, the passage divider 22 includes a small plate 221 made of corrugated metal plate,
222, . . . etc. are stacked together and fixed so that the bent portions of the corrugated plates intersect with each other in different directions. Specifically, for example, if the corrugated sheet 221 is arranged with its troughs and peaks extending in the direction of arrow a, the metal corrugated sheet 2 located immediately below it
22, these corrugated plates are arranged so that the extending directions of their troughs and peaks are in the direction of arrow b, and the contact points of these corrugated plates are welded and fixed in a crossed state. Furthermore, the metal corrugated plate 223 located immediately below the metal corrugated plate 222 is arranged so that its valleys and peaks extend in the direction of arrow a, and similarly welded and fixed in a crossed state. This is what I did. Similarly, small plates 224, 225 made of corrugated plates,
226 etc. are stacked and welded together, and the passage dividing body 22 is made by integrating these small plates.

Inside the passage divider 22, divided resin passages are formed between the small plates, but the passages are oriented in different directions between adjacent plates, and the thickness of the passages varies. Passage dividing body 22
is fixed within the cylinder so that the inner wall of the cylinder 21 is at the position indicated by the dotted line in FIG. In other words, it is inserted into the cylinder and fixed so that the direction indicated by the arrow x in FIG. 3 is the axial direction. In the static mixer 2, such passage dividing bodies 22 are arranged in series one after another with their ends close to each other, and housed in a cylinder. At this time, the ends of adjacent passage dividing bodies are
The corrugated sheets are arranged so that their extending directions intersect with each other. A device having such a structure is an example of the static mixer 2.

In addition, the passage dividing body 22 of the static mixer 2 is
It is also possible to use the dividing body 5 having a structure as shown in FIG. The passage dividing body 5 is made by combining intersections 51, 52, and 53. Specifically, a set of small plates 521, 522, 523, 524
are arranged in parallel at equal intervals on one plane, and another set of small plates 526, 527, 528, 5
29 are equally spaced parallel to each other in another plane, the latter set being interposed between the former set and the intersections welded, thus forming a platelet intersection 52. Similarly, a pair of small plates 531, 53
2,533, etc. are arranged at equal intervals and intersect with the small plates 536, 537, 538, etc. to form the intersection object 5.
2 is configured. Furthermore, in the same way, the crossing object 53
is configured. On top of that, these intersections 51,
52 and 53 are further crossed, for example, crossing object 5
The small plate 536 of 2 is the small plate 521 and 52 of the intersection 51
2, and their intersections are welded and integrated to form the passage dividing body 5. In this case, align the ends of each intersection so that they are on a straight line. In this way, the passage dividing body 5 is constructed. The static mixer 2 may include such a passage dividing body 5.

As already mentioned, the gear pump 3 has two gears meshed together within the housing to be rotatable, and actually rotates the two gears outward. Here, "rotating outward" refers to the rotation of the gear in which the resin that has entered the gear pump 3 hits the gear, is turned to the outside, and advances forward through the outside of the gear. It is. Further, it is preferable that the housing of the gear pump is of a jacket type so that a heating medium can flow therethrough and the temperature can be controlled.

According to the apparatus of this invention, the resin heated and kneaded in the extruder can be guided to the static mixer and mixed well. More specifically, inside the extruder,
Although it is possible to knead well locally with the screw 12, it is difficult to knead so that there is no difference between the part in contact with the outer surface of the screw 12 and the part in contact with the inner surface of the barrel 11. However, when this resin is guided into the static mixer 2 and passed through it, the resin that was in contact with the screw 12 can be mixed well with the resin that was in contact with the barrel 11. Therefore, according to this inventive device,
It is possible to obtain a resin that is heated uniformly as a whole. In addition, the resin that has passed through the static mixer is subject to flow resistance by the passage divider and tends to lack extrusion pressure, but by guiding this to the gear pump 3, the extrusion pressure can be appropriately replenished. . Moreover, gear pumps generally generate less heat, so the resin temperature does not rise too much.
Extrusion pressure can primarily be supplemented. In addition, since a gear pump was used, there was little pulsation in the pressure and the resin could be fed uniformly. Therefore,
According to the apparatus of this invention, it is possible to extrude the resin while maintaining the resin at a uniform temperature while applying an appropriate and uniform extrusion pressure to the resin. Therefore, according to the apparatus of the present invention, it is possible to produce a large-sized foamed molded article that has a large cross-sectional area and is well-foamed uniformly. In this respect, the device of the invention exhibits remarkable effects.

Of the two methods shown in Figures 1 and 2, the device in which the resin passes through a static mixer first as shown in Figure 1 is used when the resin exiting the extruder exhibits a high extrusion pressure. The apparatus which is suitable and shown in FIG.
Suitable when the resin exiting the extruder exhibits low extrusion pressure.

It is particularly suitable for producing foam sheets of uniform thickness from a circular die.

Next, examples and comparative examples will be described.

Example 1 Screw diameter 62m/m, L/D (length/diameter)
A 35 extruder was used with polystyrene resin, blowing agent and butane.

VACOREX45/45 (product name, West German MAAG) was used as the gear pump, and SMX type 65φ diameter (product name, Swiss Sulzer) was used as the static mixer.
A polystyrene resin foam sheet was manufactured using a circler die as a die.

In the above production equipment, a gear pump and a static mixer are used in order, the extrusion pressure of the extrusion screw is 250Kg/m ² , the rotation speed of the gear pump is 25 per minute,
Set the inlet temperature of the cap to 176℃ and measure the average thickness.
A polystyrene resin foam sheet with a small thickness deviation of 2.31 m/m and a variation R=0.15 was obtained. In this case, the extrusion rate is 42 Kg/hour.

Example 2 The same manufacturing equipment as in Example 1 was used except that the order of the static mixer and gear pump was changed.

Then, the extrusion pressure of the extrusion screw was set to 265Kg/
cm ² , the rotation speed of the gear pump is 27 per minute, and the inlet temperature of the mouthpiece is set to 177℃, and it is extruded into a cylindrical shape, the top and bottom are sandwiched between metal rolls, fused and cooled, and the average thickness is 5.35m/
A polystyrene resin foam board with m and variation R=0.22 was obtained. In this case, the extrusion rate is 46 Kg/hour.

Comparative Example 1 A polystyrene resin foam sheet was produced in the same manner as in Example 1 except that the gear pump was not used. Average thickness 2.32m/m, variation R=
Although the thickness deviation was small at 0.12, the extrusion amount was small at 35 kg/hour.

Comparative Example 2 A product was manufactured in the same manner as in Example 1 except that the static mixer was not used. It was a polystyrene resin foam sheet with a large average thickness of 2.80 m/m and a variation R of 1.57.

[Brief explanation of drawings]

1 and 2 are partially cut away vertical sectional views of the device of the present invention. 3 and 4 are perspective views of a passage divider in a static mixer used in the apparatus according to the invention. In the figure, 1 is an extruder, 2 is a static mixer, and 3 is an extruder.
is a gear pump, and 4 is a base. 11 is a barrel, 12 is a screw, 21 is a cylinder, 22 is a passage dividing body, 23 and 24 are small plates, 31 is a housing, 32 and 33 are gears, 41 is an outer mold, and 42 is an inner mold.

Claims (1)

[Scope of Claims] 1. A foamed resin extrusion molding apparatus, characterized in that a gear pump and a static mixer are arranged in series in a resin passage between an extruder and a die. 2. The device according to claim 1, which comprises a gear pump and a static mixer arranged in this order. 3. The device according to claim 1, which comprises a static mixer and a gear pump arranged in this order. 4. The static mixer is constructed by inserting a passage dividing body into a short cylinder, and the passage dividing body has a large number of divided passages therein, and the divided passage has its traveling direction aligned with the axis of the short cylinder. 2. The device according to claim 1, wherein the device is oriented obliquely to the user, and includes adjacent paths having different directions of travel, with the end of the divided path facing the base. 5. The passage dividing body consists of a large number of small plates facing different directions, which are fixed at intervals so as to cross each other, and a passage is formed between the small plates, and the surface of the small plate is at least partially formed into a short cylinder. 5. The device according to claim 4, wherein the device extends obliquely to the axis of the cylinder and is attached to the cylinder, and adjacent passages have different directions of travel. 6. A patent claim in which the small plates are made of corrugated plates, and a passage dividing body is constructed by stacking a large number of corrugated plates one after another with their peaks or valleys extending in different directions, and fixing them at points where they contact each other. Equipment described in item 4 of the scope. 7 The small plates form a set that spreads out in a plane, and 1
The platelets of another set are arranged intersectingly between adjacent platelets of one set and fixed at the points where they touch each other to form a crossing object, and the crossing objects are further fixed crosswise to each other and fixed to form a passageway. The divided body is composed of
An apparatus according to claim 6.