JPH028562B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a plasticizing and kneading device for resin in a resin molding machine or the like.

In molding machines such as extraction molding machines and injection molding machines,
Direct composite molding, in which various fillers and resins are directly introduced into a plasticizing and kneading device and molded, has various difficult problems. That is, it is extremely difficult to completely disperse the filler, and there are many difficult problems such as secondary agglomeration, cutting, and breakage of the filler. In particular, it is difficult to do this when the resin is in the form of pellets, whereas it is relatively easy to do so when the resin is in the form of beads or powder because the particle size is small, so here we will mainly explain the resin in the form of pellets.

The present invention is intended to solve these problems and mainly relates to a screw for a molding machine.

Generally, in a normal molding machine, as shown in FIG. 1, the screw 1 is composed of a supply zone 3 from the material supply hole 2 side, and a plasticization kneading zone 6 consisting of a compression zone 4 and a metering zone 5. . compression zone 4
In this case, the screw groove depth gradually becomes shallower, and the passage cross-sectional area decreases. Therefore, the material consisting of resin and filler supplied from the supply hole 2 is preheated when passing through the supply zone 3, and is transported from the supply zone 3 to the compression zone 4 while being gradually compressed by the propulsion pressure. . In the compression zone 4, the passing area of the screw groove gradually decreases, so that the material is increasingly pressurized, and its melting form takes on a form represented by the melting model shown in FIG. 2.

In FIG. 2, when the solid bed (unmelted material) 8 formed in the screw groove 7 is pressed against the inner wall of the heating cylinder 9 by the pressure in the screw groove 7,
Due to the heat from the heating tube 9 and the shearing action caused by the relative displacement between the screw 1 and the inner wall of the heating tube 9 as the screw rotates, the solid bed 8 is melted from the contact surface of the inner wall of the heating tube 9 to form a melt film 10. Molten material 12 scraped with screw flight 11
is pooled on the propulsion side of Skrill Flight 11.
However, in this melted form, the screw groove 7
Since the solid bed 8 is formed by the propelling pressure in the screw groove 7, there is no relative movement inside the solid bed 8. Therefore, the temperature of the solid bed 8 itself can only be raised depending on heat conduction from the surroundings of the solid bed 8, and the filler and resin inside the solid bed 8 are not sufficiently preheated in the compression zone 4 of the plasticization and kneading zone 6. As the pressure is applied, the fillers become more and more hardened, and even if the resin near the filler softens and melts,
This has the drawback that the resin does not impregnate between the fillers, causing undispersed lumps and secondary agglomeration. or,
Solid bed 8 pressurized without sufficient preheating
is strongly pressed against the heating cylinder 9 by the propulsion pressure generated in the screw groove 7, and receives a strong shearing force at the melt film 10 due to the rotation of the screw.
It has the disadvantage of causing cutting and damage to the filler.

In order to eliminate these drawbacks, the present invention reduces the propulsion pressure in the screw groove by providing a recess deeper than the bottom of the screw groove that communicates from the propulsion side to the anti-propulsion side of the screw flight. By causing complex relative movement of the material in the groove and increasing thermal homogeneity and heating rate,
This allows for easy melting and prevents secondary agglomeration and breakage of the filler.

Next, the present invention will be explained with reference to embodiments shown in the drawings.

FIG. 3 shows one embodiment of the present invention. FIG. 4 is an enlarged view.

In Figures 3 and 4, a screw 1 is placed inside the heating cylinder 9.
is rotatably or freely rotatable and slidably disposed in the axial direction, and the material supply hole 2 is provided with a feeder 20 to control the amount of material supplied. The screw 1 is composed of a supply zone 3, a compression zone 4, and a metering zone 5 from the material supply hole 2 side.
The compression zone 4 and the metering zone 5 will be collectively referred to as the plasticizing and kneading zone 6. In the zone 13 extending from the supply zone 3 to the plasticizing and kneading zone 6, the screw 1 has a concave portion 15 that crosses the screw flight 11 and is deeper than the screw groove bottom 14, and is opposite to the propelling side 16 of the screw flight 11. It communicates with the propulsion side 17. The feeder 20 feeds the material to the screw 1 so that the screw groove 7 does not become full, while ensuring a free space 18 in which the material can freely move within the screw groove 7.
The material is moved in feed zone 3.

The screw according to the present invention has the above-mentioned configuration, and its operation will be explained next.

As mentioned above, the feeder 20 supplies the material to the screw 1 part through the supply hole 2, but the feeder 20 is careful not to completely fill the screw groove 7 with the material.
Appropriately control the supply amount of 0. Here, it is important to secure a free space 18 so that the material can move freely in the screw groove 7, and the filling rate of the material is preferably 30 to 70%. The material is transported forward through the supply zone 3 by the rotation of the screw while being preheated by heat received from the heating cylinder 9, and in the zone 13 exhibits the mode shown in FIGS. 5 and 6.

FIGS. 5 1 to 4 show the order of action and the state of the resin, in which the material is preheated in a solid state, the temperature is raised, and the material is softened and melted. That is, as mentioned above, since there is a free space 18 in the screw groove 7, the rotation of the screw 11 causes the material to move as shown by the arrows in FIGS. 1 and 3, and the material moves like the material in the tumbler. They move relative to each other. The screw groove bottom 14 and the recess 15 provided in the flight 11 exhibit movements as shown by arrows in FIGS. 2 and 4. That is, the material moves from the propelling side 16 to the counter-propelling side 17 through the recess 15. The recess 15 also performs the operation of scooping up the material that has entered the recess 15 by rotating the screw 1 and discharging it on the opposite side. Therefore, since the material moves in an extremely complicated manner in the screw groove 7, all of the material in the screw groove 7 comes into contact with the inner wall of the heating tube 9, the side wall of the screw flight 11, and the screw groove bottom 14, and receives heat. As a result, the temperature of both the filler and the resin increases uniformly. Thus, as the resin softens under preheating and the surface of the pellet melts or becomes sticky, it begins to adhere to the filler. Since this condition is carried out under normal pressure, the fillers do not stick to each other, and the fillers are peeled off from the pellets after adhering to the molten resin on the surface layer of the pellets. Therefore, new adhesive resin and new filler always come into contact with each other, and mixing of the two progresses. This means that
This means that the fillers do not stick to each other due to the pressurizing action, meaning that secondary aggregation of the fillers does not occur, and it means that the resin can be easily impregnated between the fillers. In addition, the volatile matter and moisture content of the molten resin are easily discharged to the rear through the free space 18 in which the material can move freely within the screw groove 7. In this way, filler and resin are gradually mixed,
At the stage of transition to the plasticizing kneading zone 6, the filler and pellets have reached temperatures near the softened state just before the resin melts.

In the compression zone 4, where the passage cross-sectional area of the screw groove 7 is reduced, the screw groove 7 is filled with material, forming a so-called softened solid bed 19, as shown in FIGS.
4 shows the action order and melting mode.

FIGS. 6 1 and 3 show that the softened solid bed 19 is easily deformed and melted by a small shearing force due to the shearing action with the inner wall of the heating cylinder 9 due to the rotation of the screw.
A case is shown in which the molten material 12 containing filler is scraped off by the screw flight 11 and propelled forward. In FIGS. 6 2 and 4, in the case of a softened solid bed 19 where the resin is softened but the adhesion between the resins is not sufficient, the bed falls into the recess 15.
The solid bed 8 collapses, and the molten resin 12 comes into contact with the collapsed surface, promoting further total melting and mixing. What is characteristic here is that the propulsion side 16 and anti-propulsion side 17 of the screw flight 11 are in the recess 1.
5, the pressure maintained within the screw groove 7 is much smaller than that of a normal screw 1 as shown in FIG. The point is that you don't need it. That is, like a normal screw, the solid bed 8, which is a mixed, unmelted mixture of filler and resin whose temperature has not yet been sufficiently heated, is pressed against the inner wall of the heating cylinder 9 under high pressure, and a strong shearing action is applied to the pressed contact surface by the rotation of the screw. In addition, since the melting point is not reached all at once and melting is not completed, there is no cutting or damage to the filler, and there is no dispersion that occurs when the filler is hardened under high pressure and then wrapped in the melted resin all at once. No lumps or secondary aggregation occurs.

As described above, according to the present invention, the filler and resin are heated while being mixed under atmospheric pressure, and the filler and resin are always at about the same temperature. Since the filler and resin in the groove are at a uniform temperature everywhere, simultaneous melting and mixing of the filler and resin occur, resulting in composite molding with good filler dispersion and less breakage as described above. An extremely large effect can be obtained.

The above explanation mainly concerns the case where filler and resin are directly molded, but in the case of plasticizing only ordinary resin without filler, there are improvements in plasticizing ability, quality through homogeneous plasticization, and high quality. Cycle molding has a great effect. That is, in the case of normal molding other than composite molding, since there is no feeder 20, the screw groove 7 in the supply zone 3 is filled with unmelted resin. In addition, when not according to the present invention,
As described above, the melted state shown in FIG. 2 is obtained.

In the present invention, as described above, the resin filling the screw groove 7 of the supply zone 3 is compressed within the screw groove 7 by the propelling pressure of the screw to form the solid bed 8. Since the center of the formed solid bed 8 is dependent on heat transfer from the surroundings of the solid bed 8, the temperature distribution is different between the outer periphery and the center of the solid bed 8. The solid bed 8 is pressed against the inner wall of the heating cylinder 9, and is sequentially melted from this pressed surface and pooled as a melt 12 on the propelling side of the screw flight 11. When the solid bed 8 reaches the screw-shaped region according to the invention and passes through this region, it assumes the melting state shown in FIGS. 3 and 4. That is, the solid bed 8 is in the recess 1.
The solid bed 8 falls into 5 parts and collapses, and the molten resin comes into shear contact with the collapsed surface, promoting the temperature rise of the solid bed 8 and preventing the molten resin from further temperature rise. In this way, the melting efficiency is increased and the plasticizing ability is greatly improved. The propulsion side 16 and anti-propulsion side 17 of the screw flight 11 are communicated through the recess 15, so that the pressure maintained in the screw groove 7 is small, the pressure on the inner wall of the heating cylinder 9 is small, and the shearing force due to screw rotation is small. . Therefore, it goes without saying that plasticization caused by local overheating, which involves passing through the melting point all at once to create a high-temperature molten resin, is prevented, and a uniform molten resin can be obtained even with low-temperature resin, and localized plasticization is prevented. It has the great advantage that there is no reduction in fluidity due to melting or non-uniform melting with high viscosity parts, and high cycle molding is possible due to low temperature and high fluidity.

Note that FIG. 7 shows one example of the present invention shown in FIGS. 3 and 4.
This is a developed view of the screw 1 according to the embodiment, in which a recess 15 is provided along the axial direction, whereas FIGS. 8 and 9 show a case in which a relatively short recess 15 or a long recess 15 is provided in the circumferential direction. FIG. 6 is a developed view of the screw 1 showing other embodiments. FIG. 10 is a developed view of the screw 1 showing yet another embodiment in which a screw flight 11 and a recess 15 are provided in the direction of the reverse thread.

Good plasticization and kneading can be obtained in the cases shown in FIGS. 8 to 10 as well as in the cases shown in FIGS. 3 to 7.

As described above, according to the present invention, in a recess that is deeper than the depth of the screw groove that traverses the screw flight,
By communicating the propulsion side and anti-propulsion side of the screw flight, the propulsion pressure in the screw groove is reduced, and the material in the screw groove undergoes complex relative movement, improving thermal homogeneity and temperature rise rate. By increasing the melting point, melting can be carried out without strain, and secondary agglomeration and breakage of the filler can be prevented. Therefore, good plasticization and kneading can be performed, and a resin molded product of good quality can be reliably and easily obtained.

[Brief explanation of drawings]

FIG. 1 is a front view showing an example of a conventional device similar to the present invention, FIG. 2 is an explanatory diagram showing the melting form of resin in the device of FIG. 1, and FIG. 3 is an illustration of an example of the present invention. The front view shown in Fig. 4 is an enlarged view of a part of Fig. 3.
5. 1 to 4 and 6. 1 to 4 are explanatory diagrams showing the melted form of the resin in the apparatus of the present invention, respectively. FIG. 7 is a developed view of the screw shown in FIG. 4, and 8 to 1.
Figure 0 is a developed view of the screw portion showing other embodiments of the present invention. 1... Screw, 2... Resin supply hole, 3... Supply zone, 6... Plasticization kneading zone, 7... Screw groove, 8... Solid bed, 9... Heating cylinder,
11...Skrillophrite, 12...Melted body, 1
4... Screw groove bottom, 15... Concavity, 16... Propulsion side, 17... Anti-propulsion side, 18... Free space, 1
9...Softened solid bed, 20...Feeder.

Claims (1)

[Claims] 1. A rotatable or freely rotatable screw that is slidable in the axial direction is provided in the heating cylinder, and a supply zone and a plasticization kneading zone are provided from the material supply hole side in the screw part, and the supply zone and the plasticization kneading zone are connected to each other. A plasticizing and kneading device for resin, characterized in that the propulsion side and the counter-propulsion side of the screw flight are connected to each other by a recess deeper than the depth of the screw groove that crosses the screw flight in either or both of them.