JPS6147692B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for manufacturing a plastic molded article in which a reinforcing material or a filler is mixed.

It is already known to strengthen extruded synthetic resins by adding additives such as glass fibers, carbon fibers or mica, and to fill them with cheaper fillers as additives to obtain cheaper plastics. In order to obtain such a mixed plastic, the raw resin and additives are put into a hopper and heated and kneaded using an extruder, or the raw resin and additives are premixed in a tumbler etc. It is known to feed pellets into an extruder to obtain pellets.

However, when trying to obtain a molded article by such a method, the glass fibers and the like are broken because the raw materials are subjected to high shearing force from the molding machine when melted. For this reason, even if a molded article is molded using an injection molding machine using the produced pellets, the reinforcement with glass fibers is insufficient. Furthermore, since the glass fibers have high hardness, the screws and cylinders of the extruder were subject to a large amount of wear.

In order to solve this problem, it has been proposed to provide a supply hole for injecting the additives behind the hopper that injects the raw resin in order to add the additives after the resin is melted. When the amount was large, the molten raw material resin was cooled and solidified due to the heat taken away by the additives, and the supply holes were sometimes clogged with additives, making it impossible to operate.

Furthermore, the raw material resin injected from the hopper is sent out through the feed section transition section of the screw and the adjustment section. Behind the adjustment section, a low pressure section with a groove depth greater than the above three sections is provided, and this low pressure section is used for supplying additives. A method has been proposed in which an auxiliary screw is provided. This method also does not completely eliminate the above-mentioned drawbacks, and in addition, it is difficult to remove material near the joint between the auxiliary screw and the main screw when changing materials, etc., which limits its use. In addition, the mechanism became complicated because the rotation speeds of the main and auxiliary screws were each controlled independently.

The present invention eliminates these drawbacks, and its purpose is to provide a method and apparatus for producing an extruded product that has a simple mechanism, low cost, and is easy to handle.

The details of the present invention will be explained below with reference to FIG. 1 showing one embodiment. Cylinder 1 of twin screw extruder
A main screw 2 is rotatably inserted into the cylinder 1 (only one side is shown in the figure), and a first cylinder that receives solid or molten raw material resin is located at the base end side of the cylinder 1 (right side in the figure). A supply hole 3 is provided,
A weighing feeder 4 for raw resin is installed above it. Further, in the middle of the cylinder 1 is a second supply hole 5 for receiving additives, and above it is provided a metering feeder 6 for supplying additives.

The base end of the second supply hole 5 of the main screw 2 has a reverse thread 7, which prevents the molten raw resin from advancing in this portion. A conduit 8 is opened in the cylinder 1, sandwiching the second supply hole 5, and the resin whose progress is prevented as described above passes through this conduit 8. Further, the horizontal portion of the conduit 8 is formed by a lid 9 fixed to the cylinder 1 with bolts (not shown) or the like.

Next, the operation of the present invention will be explained. The resin supplied from the first supply hole 3 to the cylinder 1 via the metering feeder 4 is kneaded and melted by the rotation of the main screw 2 and advances forward, where it is stopped at the reverse threaded portion 7. , the resin advances through conduit 8, which is a bypass path, and is fed into main screw 2 again from conduit 8A. Second supply hole 5
Additives such as glass fibers supplied from the main screw 2 are fed by the main screw 2 and come into contact with the molten resin at the portion facing the pipe line 8A, and then kneaded into the molten resin by the main screw 2. The kneaded resin is transferred to the main screw 2.
The bend portion 10 contacts the vent hole 11 and water vapor and volatile gas are extracted. Note that the vent hole 11 is connected to a vacuum source as necessary. The raw resin and additives are sent out from the orifice 12 of the cylinder 1 while being further kneaded.

FIG. 2 shows another embodiment of the present invention, and this embodiment differs from the previous embodiment only in the shape of the bypass passage, and is otherwise the same. A conduit 17 provided in the main cylinder 16 is inclined downward (in the figure) and its lower end is held down by a lid 18.

FIG. 3 also shows another embodiment of the present invention.
If it is difficult to supply the additive by simply dropping it as in the first and second embodiments described above, a forced feeder 21 is provided between the additive supply feeder 6 and the cylinder 1 to remove the additive. cylinder 1
By doing so, even light and fluffy additives such as mica can be reliably fed into the cylinder 1.

4 and 5 show other embodiments of the present invention. In the first example, the main screw 2 was provided with a reverse thread 7, but in this example, a cylinder is installed in the reverse thread. 1 has a ring 22 with a small gap, and the molten resin is prevented from advancing by this ring 22.

As described above, the extruded product manufacturing method and manufacturing apparatus of the present invention is a twin-screw extruder in which a resin supply hole is provided at the base of the cylinder and an additive supply hole is provided at the middle of the cylinder. A reverse screw or ring is provided on the screw at the base end to prevent the molten resin from advancing, and a conduit is placed from the base end of the reverse screw or ring to the cylinder to allow the molten resin to flow. It was configured to be bypassed and sent to the end of the additive supply hole.

Therefore, since the additive supply hole is opened in a portion where there is no molten resin, the molten resin is not cooled by the additive. Therefore, according to the present invention, it is possible to stably supply a large amount of additives. Furthermore, since no auxiliary screw is required, the mechanism is simple and the cost is low, and furthermore, when changing materials, the resin can be easily removed by removing the lid and the material can be changed.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of one embodiment of the present invention, FIGS. 2 to 4 are longitudinal cross-sectional views of main parts in other embodiments of the present invention, and FIG. 5 is a cross-sectional view taken along line A-A in FIG. 4. It is a diagram. 1... Cylinder, 2... Main screw, 3... Raw resin supply hole, 5... Additive supply hole, 7... Reverse screw, 8, 17... Pipe line, 21... Ring.

Claims (1)

[Scope of Claims] 1. In a manufacturing method in which raw resin and additives are kneaded and extruded using a twin-screw extruder, the raw resin supplied from the base end of a cylinder is melted by a main screw, and then the raw resin is The additive is supplied to the cylinder without molten resin by returning the additive from the cylinder to the cylinder through a pipe line serving as a bypass path at the intermediate part and supplying the additive to a portion of the cylinder facing the pipe line. A method for producing an extruded product, wherein the molten resin and the additive are then kneaded and extruded. 2 In a twin-screw extruder that kneads and extrudes raw resin and additives, a raw resin supply hole is provided at the base end to supply raw resin, and an additive is provided in the middle to supply additives. a cylinder having an additive supply hole, a main screw which is rotatably inserted into the inner hole of the cylinder and has a reverse screw or a ring at a portion that contacts the base end side of the additive supply hole; An extruded product manufacturing apparatus having a reverse thread of the main screw or a pipe line leading from the base end side of the ring to the tip of the additive supply hole. 3. The extruded product manufacturing apparatus according to claim 2, characterized in that glass fiber is used as an additive. 4. The extruded product manufacturing apparatus according to claims 2 and 3, characterized in that the additives are fed through a forced feeder.