JPS63122513A - High-dispersion screw for injection molding - Google Patents

Abstract

PURPOSE:To provide a screw through which high dispersion due to low back pressure is obtained, by a method wherein a mixing part is provided and the beginning part and terminal part of a sub-flight are connected by a weir running parallel with an axial direction with a main flight. CONSTITUTION:A sub-flight 36 whose height is a little lower than that of a main flight 32 and lead angle is larger than that of the main flight 32 is provided. As a weir 37 running parallel with a shaft is connected with the main flight 32 at the beginning part and terminal part, an unmolten material is molten at the time of crossing of the unmolten material over the weir 37. The beginning part and terminal part of the weir 37 are connected smoothly in a straight line or a curved line continuously with a screw groove so that they become shallow gradually from a depth of the groove, and a high-kneading effect is kept at these parts. On the one hand, as a mixing part having high dispersibility is provided on the tip part of a metering zone M of this screw, a high dispersibility due to low back pressure is obtained.

Description

[Detailed description of the invention] [Objective of the invention] (Industrial field of application) This invention relates to a screw for injection molding, and is related to improving the dispersibility of pigments in dry colors, liquid colors, masterbatches, etc. technology) In order to melt plastic materials and improve kneading and dispersion, as shown in Figure 5, a plunger 2ff with a small gap between the cylinder and the cylinder is installed as shown in Japanese Patent Publication No. 43-24493. The grooves 3 and 4, which do not penetrate through the outer peripheral surface of the plunger 2, are alternately arranged in opposite directions so that they do not communicate with each other, or the actual publication 5 shown in FIG.
No. 8-138613.

Youni Feed Zone F1 Congression Zone C1
In the screw 11 having metering zone Mi, compression zone C or metering zone M
A mixing flight 12 of a single thread or multiple threads is provided over a predetermined range of at least one of A screw formed in such a way that the changes in depth of grooves adjacent to each other in the direction are opposite to each other, or a sub-flight 22 branched from the main flight 21 as shown in Utility Model Publication No. 55-1810 in Fig. 7. There is a screw that connects to the main flight 2+ on the downstream side.

(Problems to be Solved by the Invention) In the conventional screw described above, it was necessary to apply a high back pressure of 20 to f/i or more in order to obtain sufficient color dispersion.As a result, the plasticizing ability decreased. However, there are drawbacks such as an increase in resin temperature, a decrease in productivity, and a decrease in the quality of molded products.

An object of the present invention is to provide a screw that can obtain high dispersibility due to low back pressure due to high kneading performance.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve all of the above-mentioned objectives, we have developed a plastic molding screw that has high kneading properties and a molten functional gold sub-flight screw that provides high dispersion ability in the mixing section. In a plastic molding screw that forms a feed zone, a compression zone, and a metering zone from the material supply side to the material discharge side, there is a small gap between the metering zone and the cylinder. On the outer circumferential surface of the plunger, mixing portions are provided that are alternately arranged in opposite directions so that the non-penetrating first-stop grooves do not communicate with each other, and mixing portions are provided on the outer circumferential surface of the plunger, and mixing portions are arranged alternately in opposite directions so that the non-penetrating first-stop grooves do not communicate with each other. The sub-flight has at least one sub-flight slightly lower than the main flight, and the starting and ending ends of the sub-flight form a weir parallel to the axial direction and are connected to the main flight, and the weir is connected to the main flight on the downstream side and On the upstream side,
This high dispersion screw for injection molding of plastics is characterized in that it is continuously and smoothly connected to the bottom surface of the screw groove by a straight line or a curve, and has a height slightly lower than the sub-flights.

(Function) In order to improve the kneading and dispersion of plastic materials, a mixing section is provided to improve color dispersion, and a sub-flyer is provided to compensate for the decrease in plasticizing ability caused by the mixing section.0 (Example) Fig. 1 , FIG. 2 and FIG. 3 to explain one embodiment of the present invention. The plastic material supplied from the material supply port 31 is transferred to the feed zone F1 and compression zone C1.
032, which transports the metering zones M in the order of the arrow X direction, is a main flight that is continuously provided from the feed zone F to the metering zone M at equal pitches.

Reference numeral 33 denotes a mixing section, which has a grunger-like groove 34 with a small gap between it and the cylinder, and is a stopper that does not penetrate the outer peripheral surface.
and 35 are provided, and are alternately arranged in opposite directions so that they do not communicate with each other.

FIG. 2 is an enlarged view of the Y section in FIG. 1, showing that the main part of the screw of the present invention is completely formed, and a sub-flight 36 is provided, which is slightly lower in height than the main flight 32 and has a larger lead angle, and its starting and terminal ends. A weir 37 parallel to the axis connects the main flight 32 at a portion. Therefore, to prevent the material from passing through unmelted, which is the case with conventional open types,
This ensures that the unmelted material that crosses the weir is melted when it crosses the weir 37. Therefore, it has a property intermediate between an open type and a closed type so that the material does not stagnate and melts. Furthermore, in order to ensure that the heat from the barrel that covers the outer peripheral surface of the screw is well transmitted, the starting and ending ends of the weir 37 are continuously formed in a straight line or a curved line so that the depth of the screw groove gradually becomes shallower, as shown in Fig. 3. Connects smoothly. Therefore, this part also has the effect of high kneading performance, while the tip of the metering zone M of this screw has the conventional feature of high dispersion. Since the mixing section is provided with a mixing section, it has the effect of obtaining high dispersibility due to low back pressure.

Next, a comparison test was conducted between the screw in accordance with the present invention (FIG. 1) and the conventional screws in FIGS. 8, 9, and 10. Molded product; fly (shown in FIG. 4) weighs 315 yr.

Resin: Mixing ratio of dry color to PP is 0. +9
6. Mixed molding conditions at 0.4 kou and 0.8% Screw rotation speed: I 75 cp, m (MAX) back
Pressure: 0,10,20 Kyf/cd Cycle: Injection 5 seconds, cooling 15 seconds, 1 cycle 34
Second barrel temperature: 225℃ Molding machine: l5-550E (manufactured by Toshiba Machine) Clamping force 55Q
tun and screw diameter of 75. The color dispersion status was compared using a color difference meter under the above-mentioned molding conditions, and the results shown in the table below were obtained.

In the table: ×: Bad Δ: Fair \ Good ○: Good As shown above, the screw of the present invention has a low back pressure of 20 Kgf/m
It also has high dispersibility in the following 0

[Brief explanation of the drawing]

FIG. 1 is a diagram showing one embodiment according to the present invention. Figure 2 is the first
Enlarged view of part Y in the figure. FIG. 3 is a sectional view taken along line II in FIG. FIG. 4 is a diagram of a test product for comparison between the present invention and a conventional example. The fifth factor is a conventional screw having a mixing part. FIG. 6 is a diagram of another conventional example having a mixing part. FIG. 7 is a diagram showing still another conventional screw, which is a screw having sub-flights. Figures 8, 9, and 10 are diagrams of conventional screws.
The figure shows a short sub-flight with open grooves at both the beginning and end of the compression zone. Figure 9 shows the next screw with the mixing section installed in full flight. Figure 10 shows that the combination zone has a short sub-flight with both the groove start and end open, and a mixing section is installed at the tip. 7 lights, 33
,...Mixing section, 34.35...First stop groove, 36...Sub flight, 37...Weir, F
...Feet zone, C...Compression zone, M...Metering zone.

Claims (1)

[Claims] 1. In a screw for plastic material molding that forms a feed zone, a compression zone, and a metering zone from the material supply side to the tip end of the material discharge side,
On the outer peripheral surface of the plunger having a small gap between it and the cylinder at the tip of the metering zone, mixing portions are provided which are alternately arranged in opposite directions so that the non-penetrating first-stop grooves do not communicate with each other. , having a sub-flight slightly lower than the main flight at at least one location across either the compression or metering zone, or both zones, and the starting and ending ends of the sub-flight are parallel to the axial direction. A plastic injection molded high dispersion screw that forms a weir and connects with the main flight. 2. The screw according to claim 1, wherein the weir is continuously and smoothly connected to the bottom surface of the screw groove in a straight line or a curve on its downstream and upstream sides. 3. The screw according to claims 1 and 2, wherein the height of the weir is slightly lower than that of the subflight.