JPS5838309B2 - Multilayer composite extrusion equipment - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a multilayer composite extrusion device, and more specifically, it aims to improve the accuracy of the thickness ratio of multiple layers and adjust the thickness ratio. The present invention relates to a multilayer composite extrusion device characterized by easy operation.

Conventionally, various extrusion devices have been proposed for the purpose of obtaining composite extrusion-shaped articles consisting of multiple layers.

For example, a so-called coextrusion method using a plurality of extruders can be mentioned.

This method is distinguished by the method of combining the molten resin,
It is roughly divided into the multi-manifold method in which the molten layers are combined within the die, the multi-slot method in which the molten layers extruded from the die are combined, and the compound adapter method in which the molten layers are combined in a part of the adapter in front of the die.

In these methods, resins with different properties are input into multiple extruders, and composites made of various resins can be obtained. Used for coating.

However, on the other hand, the shape of the die is generally complex, and the effects of the temperature, rotation speed, and other condition settings of multiple extruders are delicate, so there are drawbacks such as the need for a large number of automatic measurement and control devices, which increases equipment costs. have.

Furthermore, even if the supply amount of each extruder to the die is stable, in the multi-slot method and multi-manifold method, in which thickness adjustment is performed individually, the thickness adjustment work depends on the flow state of each resin. This will have a major impact and will be a very complicated task.

On the other hand, the combined adapter method uses a crosshead die etc. to combine resins with different properties, so it has the disadvantage that it requires a lot of empirical elements when approaching a cylindrically symmetrical structure. ing.

The present invention has been made in view of the drawbacks of the conventional methods, and provides a multilayer composite that is characterized by improving the thickness composition ratio and accuracy of the covering layer, and making it easy to adjust the thickness composition ratio. This invention relates to an extrusion device.

However, the gist of the present invention is that a pipe hole leading from the surface of the screw to the tip of the screw is provided in the region after the plasticization zone of the resin kneading screw of a single-screw extrusion device, and all of the plasticized resin is disposed in the pipe hole. A weir is provided close to the entrance of the tube hole, and a weir is provided to introduce at least a large part of the water into the tube hole, and a conduit hole is provided that leads to the screw surface from the middle of the tube hole, and a weir is provided between the conduit hole and the weir. In a multilayer composite extrusion device in which a second resin supply port is provided in a cylinder corresponding to a portion of The multilayer composite extrusion apparatus is characterized in that the resin supply port is provided with a mechanism for forcibly supplying another molten resin.

The present inventors previously proposed a multilayer composite extrusion apparatus similar to the present invention in Japanese Patent Application No. 55-63276, but the present invention has been improved to be particularly suitable for manufacturing multilayer pipes and the like.

Hereinafter, the present invention will be explained using the drawings as an example of manufacturing a two-layer pipe. The drawings show a cross section of the main parts of the composite extrusion device according to the present invention, where 1 is a cylinder, 2 and 3 are
are first and second resin supply ports provided in the cylinder 1, respectively, and 4 is a screw.

Reference numeral 5 denotes a pipe hole inlet located on the outer surface of the screw 4 and provided between a portion of the screw corresponding to the first resin supply port 2 and the second resin supply port 3; It communicates with the tube hole 6 which communicates with the.

T is a weir provided between the pipe hole inlet 5 and the second resin supply port 3, and is a weir that prevents the resin material A supplied from the first resin supply port 2.
It plays the role of causing the water to flow into the tube hole 6 from the tube hole entrance 5.

Furthermore, if necessary, a resin material A and a second
In order to actively mix the resin material B supplied from the resin supply port 3, a mixing channel 81 or a guide hole 82 for mixing a part of the molten resin A into the molten resin B is provided.

Reference numeral 13 denotes a forced extruder for supplying the resin material B attached to the second resin supply port.

Breaker plates 91 and 92 have the effect of preventing foreign matter from flowing out or increasing back pressure when used in combination with a screen.

By providing the breaker plate 91 within the screw, it is possible to avoid streaks caused by the difference in flow characteristics of the molten resins A and B.

Especially when the extruded product is thin like a film,
The effect in terms of improving appearance characteristics is more significant.

Next, the area between the first resin supply port 2 and the weir 7 is defined as a first melt-kneading section, and the area between the second resin supply port 3 and the screw tip is defined as a second melt-kneading section.

The resin material A introduced into the first resin supply port 2 passes through the first melt-kneading section, is introduced into the tube hole 6 from the tube hole inlet 5, passes through the breaker plate 91, and is extruded to the tip of the screw.

At this time, a part of the molten resin is mixed with the flow path 81 or the guide hole 8.
2, flows into the outer surface of the screw in the second melt-kneading section, passes through the second resin supply port 3, and enters the forced extruder 1.
The molten resin A flowing through the pipe hole 6 through the second molten cross-conducting section while being mixed with the molten resin B supplied from 3 is concentrically delivered to the pressure cap 10, the adapter 11, and the pipe. It is extruded as a pipe through a die 12.

When the resin pressure of molten resin B is higher than that of molten resin A, a part of molten resin B flows into the pipe hole 6 through the mixing channel 81 or the guide hole 82, and is extruded while being mixed with the molten resin A. .

In the composite extrusion apparatus of the present invention, the amount of molten resin A to be diverted to the second melt-kneading section is determined so as to maintain the pressure difference between the first and second melt-kneading sections within a range that provides necessary and sufficient adhesive strength between different resins. Shape of weir 7 or pipe hole 6 and guide hole 8
It is determined by considering the cross-sectional area ratio, etc.

In the extrusion device of the present invention, the structure of the screw in the second melt mixing section is suitable for the mixing effect, but it is necessary to have a propulsive force smaller than the propulsive force of the forced extruder 13. be.

By using the curling screw, screw 4
acts effectively to melt and knead and extrude resin material A, but substantially only the kneading effect acts on resin material B and contributes little to the extrusion driving force.
The extrusion amount is controlled by the propulsive force of the forced extruder 13,
As a result, the extrusion amounts of resin materials A and B can be adjusted independently, which has the advantage of not being limited to a narrow operating point as in conventional coextrusion methods.

Examples of the shape of such a screw include a dalmage structure with a relatively large helical angle, a diamond cut structure, and a bottle structure.

In the present invention, the thickness ratio of the composite can be easily changed during operation by relatively changing the screw rotation speed of the screw 4 and the extruder 13 for forced extrusion. Cap 10 or
Floating school? There is an advantage that the gap d between the screw tip and the pressure cap 100 can be varied over a wide range by changing the gap d between the screw tip and the pressure cap 100 as shown in the drawings using a screw etc. 3 Furthermore, in the present invention, at the tip of the screw 4,
Since molten resin material A is concentrically introduced into the die while molten resin material B is being introduced into the die, the accuracy of the resin composition ratio is higher than the conventionally proposed combined adapter method, multi-manifold method, multi-slot method, etc. It has the advantage that improvements can be achieved under easier working conditions.

The main object of the present invention is to provide an extrusion device for efficiently extruding a composite material having a multilayer structure. It is important to prevent the molten resin from mixing at the tip of the screw as much as possible, and for this purpose, the cross-sectional shape of the tube hole 6 must be a perfect circle, and the axial center of the screw and the axial center of the tube hole must be aligned. It is desirable to be present.

The resin used in the extrusion apparatus of the present invention includes all thermoplastic resins that can be extruded or shaped, and various resins can be selected depending on the intended composite material.

In addition, fillers, antioxidants, foaming agents, etc., as necessary.
It is also possible to add processing aids such as crosslinking agents and waxes, or additives such as flame retardants, stabilizers, and plasticizers. It is also possible to inject via a metering pump or the like.

Since the composite extrusion device of the present invention has the above-mentioned structure, it is easy to set extrusion conditions and efficiently extrude or shape a composite extruded shaped product having a multilayer structure without causing delamination. is possible.

In the above description, an example of manufacturing a multi-layered pipe has been described, but the composite extrusion apparatus of the present invention can also be applied to manufacturing T-die films, pipes, foamed products, and even bottles. .

[Brief explanation of drawings]

The drawing is a cross-sectional view of a main part showing the structure of a composite extrusion device embodying the present invention. Explanation of symbols, 1...Cylinder, 2...
・First resin supply port, 3...Second resin supply port, 4
...Screw 5 ...Pipe hole inlet, 6
... Pipe hole, 7 ... Weir, 81 ...
・Mixing channel, 82... Guide hole, 91, 92...
... Breaker plate, 10 ... Pressure cap, 11 ... Adapter, 12 ...
- Pipe die, 13... Extruder for forced pushing.

Claims (1)

[Claims] 1 A pipe hole leading from the screw surface to the tip of the screw is provided in the part after the plasticization zone of the resin kneading screw of the single-screw extrusion device, and all or most of the plasticized resin is introduced into the pipe hole. A weir is provided close to the entrance of the tube hole, and a guide hole is provided that leads to the screw surface from the middle of the tube hole, and a weir corresponding to the part between the guide hole and the weir is provided. In a multilayer composite extrusion device in which a cylinder is provided with a second resin supply port, the screw shape after the second resin supply port is constituted by a mixing section with substantially no propulsive force, and the second resin supply port A multilayer composite extrusion device, characterized in that it is provided with a mechanism for forcibly feeding another molten resin.