JPH0999473A - Hollow molded product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the reutilization of even a molding loss material by interally molding the respective parts of a hollow molded product by using material qualities corresponding to uses by gradually changing a first resin material along a boundary surface to connect a second resin material different therefrom. SOLUTION: In order to extrude the parison P10 corresponding to the part P10 composed of HD-PE of a pipe, a valve 9 is opened to operate a first extruder 3 and a valve 10 is closed to stop a second extruder 4. When the parison P10 is extruded by the length l10 corresponding to the L10 part of the P10 part of a product P, a control means 11 closes the valve p to stop the first extruder 3 and the valve 10 is opened to operate the second extruder 4. By this constitution, the material of the extruded parison (p) is changed over to LD-PE corresponding to the bellows part P2 of the pipe P. In this case, since shutoff valves 9, 10 are separated from an extrusion part 6d, the extruded material is gradually changed over and the boundary surface thereof is obliquely formed with respect to an extrusion direction.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a hollow molded article which is basically a single layer and is made of a resin material.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 1, a main body portion 1 is formed in a three-layer structure in which a foam material 1b having an excellent heat insulating property is sandwiched between inner and outer layers 1a and 1c having high rigidity. In order to integrally form the capping means such as a mountain, the mouth portion 2 which needs to be particularly rigid, when manufacturing a container C or the like made of a highly rigid single material, only the mouth portion 2 is separately molded to form the main body 1. It is usually secondary to adhere to. However, the secondary fixing method is required not only to spend more manufacturing steps but also to secure the necessary fixing strength.

Further, particularly in the production of resin molded products whose material costs are relatively high, reuse of the loss portion generated in the molding process is an important issue, but as shown in FIG. Many kinds of materials are mixed in the loss generated in the molding of the three-layer structure product, and the reuse thereof is not easy.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and it is easy to integrally form each part of a hollow molded product with a material configuration according to the application and to produce a loss material that is generated. It is an object of the present invention to provide a hollow molded article provided with a composite material suitable for reuse.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the constitution of the present invention will be specifically described based on Examples. First, one embodiment of a manufacturing apparatus in which the method of the present invention is carried out will be described based on the schematic view of FIG. The production apparatus of this example, FIGS. 3 (a) are shown as bellows portion P _2, for example, low density polyethylene (LD
-PE) and other parts P ₁₀ and P ₁₁ are made of a hard material such as high-density polyethylene (HD-PE) to improve the stretchability of the bellows part.
As shown in (b), the fitting portion J ₂ is made of a soft material and the other portion J ₁ is made of a hard material to improve the fitting performance, or a bent portion V _{2 as} shown in FIG. 3 (c). Is an apparatus intended to manufacture a hollow product having two kinds of material configurations, such as an elbow V in which the joint portion V ₁ is formed of a soft material and the joint portion V ₁ is formed of a hard material to improve the adaptability to the use place. .

In FIG. 2, there are provided two first and second parison extruders 3 and 4 each having a screw 5 disposed in each of the flow passages 3a and 4a formed therein. ,
Each tip is connected to a common nozzle 6. Therefore, the thermoplastic resin material supplied from each hopper (not shown) is heated and melted, and is made to flow in each flow path toward the nozzle 6 as the screw 5 rotates. The nozzle 6 is arranged so as to pour out the sent resin material vertically downward. A mandrel 6a having a tapered lower end is vertically arranged at a substantially central portion of the nozzle 6.
This central portion, ventilation holes 6a ₁ is drilled which is connected to a pressurized gas supply source, such as a compressor 6a _2. Around the mandrel 6a, the first flow path 7 is provided with the mandrel 6a.
Is formed along the axial direction of. Further, a second flow path 8 partitioned from the first flow path 7 by the inner pipe member 6b is formed outside the first flow path 7, and the second flow path 8 has a flow direction in the mandrel 6a. A flow region is formed by the outer pipe member 6c so as to extend along the axial direction of. The lower ends of the first flow path 7 and the second flow path 8 merge near the lower end surface of the nozzle 6 to form a parison spout 6d. on the other hand,
The upper portions of the first and second flow passages 7 and 8 are bent in the lateral direction of the nozzle 6, and the first flow passage 7 is the flow passage 3a of the first extruder 3.
The second flow path 8 is communicated with the flow path 4a of the second extruder 4, respectively. A mold set (not shown) for accommodating the poured parison and performing blow molding is arranged immediately below the nozzle 6.

Thus, for example, as in this example, the extruders 3, 4 are
Shut-off valves 9 and 10 capable of appropriately shutting off the flow paths 3a and 4a are provided at a connecting portion between the nozzle 6 and the nozzle 6. The shut-off valves 9 and 10 are control means 11 respectively.
And opens and closes each flow path 3a, 4a in accordance with an instruction from the control means 11. Therefore, by using, for example, a microcomputer as the control means 11, a suitable operation pattern corresponding to the material composition of the product to be molded is stored as a program, and each shut-off valve is opened / closed in accordance with the program to obtain the desired material. A parison is formed by pouring in the composition. In this case, the operations of the shut-off valves 9 and 10 and the extruders 3 and 4 are appropriately interlocked with each other to form the flow paths 3a and 4a.
It is necessary to prevent the internal pressure from rising abnormally. In addition, the detection means PD such as a photoelectric tube captures the light beam from the light source LS whose length of the parison to be poured out is arranged in the vicinity of the area directly below the nozzle 6, and the control means 11 responds to the signal sent from this detection means. Alternatively, the operation of the shutoff valves 9 and 10 may be controlled.

Next, one embodiment of the method of the present invention will be described based on the operation of the above-mentioned manufacturing apparatus. By the way, when the pipe P having the bellows portion P ₂ shown in FIG. 3A is manufactured, for example, LD-PE is used as the raw material as the soft resin for the bellows portion P ₂ and the other portion P ₁₀ , P ₁₁
As the hard resin for use, for example, HD-PE may be used, but other combinations such as hard vinyl chloride and soft vinyl chloride may be used. A soft resin and a hard resin, which are easily melted with each other, preferably have a combination of materials of the same system such as this example from the viewpoint of strength of the boundary portion, but interposing an adhesive or the like even in a combination of materials having poor affinity. It is possible to apply by. Now, the extruder is selected to supply HD-PE to the first extruder 3 and LD-PE to the second extruder 4. Then, HD-PE is caused to flow in the flow path from the flow path 3a through the shutoff valve 9 and the first flow path 7 to the spout 6d, and from the other flow path 4a through the shutoff valve 10. LD- is provided in the flow path through the second flow path 8 to the spout 6d.
Let PE flow through.

First, in order to extract the parison p ₁₀ corresponding to the portion P ₁₀ of HD-PE of the product pipe P, the valve 9 is opened to operate the first extruder 3 and the valve 10 is closed. The second extruder 4 is stopped. Parison p
₁₀ is a length l corresponding to the length L ₁₀ of the P ₁₀ portion of the product P.
_When only _{10 is} dispensed, the control means 11 equipped with a microcomputer closes the valve 9 to stop the first extruder 3 and opens the valve 10 to operate the second extruder 4 based on a predetermined program. As a result, the material of the parison p poured out is LD-PE corresponding to the bellows portion P ₂ of the pipe P.
Is switched to. In this case, each shutoff valve 9,
Since 10 is separated from the spout 6d, the material to be spouted immediately following the opening / closing operation of the shutoff valves 9 and 10 is gradually switched without being changed. Therefore, as shown in the drawing, the boundary surface is formed obliquely with respect to the pouring direction, but this is practically inconvenient and, on the contrary, contributes to increasing the strength of the boundary portion where the mechanical strength decreases. To do. L
When the parison p ₂ portion made of D-PE is poured out by l _{2 having} a length corresponding to the length L ₂ of the bellows portion P ₂ , similarly, the control means 11 pours out the first parison p _10. The operating state of each valve and each extruder is switched to the above state, and the parison made of HD-PE corresponding to the P ₁₁ portion of the pipe P is poured out. After the parison p having a material constitution corresponding to the material constitution of the pipe P thus formed is housed in a mold (not shown) arranged immediately below and clamped, the parison p is pressed from, for example, the ventilation hole 6a _1. If blow molding is performed by blowing pressurized gas,
As shown in (a), the pipe P having the bellows portion P ₂ with high elasticity can be obtained. Of course, any other known method can be used as the blowing method.

In the above embodiment, the shutoff valves 9 and 10 and the operations of the first and second extruders 3 and 4 are interlocked to switch the pouring material of the parison. For products whose boundary can be expected to be relatively long, the shut-off valves 9 and 10 are omitted and only the first and second extruders 3 and 4 are driven and controlled by the control means 11 to obtain a parison having a desired material structure. It is also possible.

Next, another embodiment of the device of the present invention will be described with reference to the schematic view of FIG. In the following embodiments, the same components as those in the above embodiment are designated by the same reference numerals and the description thereof will be omitted. In this example, the two systems of passages for passing two kinds of materials are opened and closed by moving the mandrel 12 in the longitudinal axis direction without using the shutoff valve. That is, as shown in FIG. 4, the upper portion of the mandrel 12 that is inserted and supported in the nozzle 6 so as to be movable in the longitudinal axis direction is connected to the driving means 13 such as a hydraulic device. This drive means 1
3 is likewise connected to the control means 11.

Thus, at the lower end portion of the mandrel 12 near the spout 6d, the projection or the engaging portion 1 is provided over the entire peripheral surface thereof.
4 are formed. Further, at the lower end of the inner surface 6b ₁ of the inner pipe portion 6b facing the peripheral surface of the mandrel 12, a projection or an engagement portion 15 is projected at a position slightly above the projection or the engagement portion 14. It is formed along the inner peripheral surface of the part or the engaging part 14 so as to be engageable. Therefore, by moving the mandrel in the vertical direction, the first flow path 7 is opened and closed, and the flow rate of the material flowing therethrough can be adjusted.

When manufacturing the hollow molded product having the structure shown in FIGS. 3A to 3C by the apparatus of this embodiment, the mandrel 12 is lowered to open the first flow path 7 and the second extrusion. It suffices to stop the machine 4 and switch the material. Further, in order to more freely switch the two types of pouring materials, the shut-off valve 10 may be provided only in the flow path 4a of the second extruder 4. Further, the nozzle 6 is configured so that the inner pipe portion 6b is movable in the vertical direction.
As shown in FIG. 3, protrusions 16 and 17 are formed on the outer peripheral surface of the inner pipe portion 6b forming the second flow path 8 and the inner peripheral surface of the outer pipe portion 6c so that the inner pipe portion 6b can be engaged with the inner pipe portion 6b. You may.
In this case, the material to be extracted can be sharply switched by moving the inner pipe portion 6b up and down.

[0014]

As described in detail above, according to the present invention, the pouring of plural kinds of materials is controlled in accordance with the material composition of the product to be molded to form the parison, so that the composite according to the application can be obtained. It becomes possible to easily form a hollow molded product including a material.
Further, since the material pouring can be controlled so that the loss material generated each time a hollow molded article made of a plurality of materials is molded becomes a single material, the recycling rate of the loss material can be significantly improved. Therefore, it becomes possible to inexpensively manufacture a high-quality hollow molded product having a composite material suitable for the purpose. It should be noted that the present invention should not be limited to the embodiments having the above characteristics, and various modifications can be made within the technical scope of the present invention.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a container C having a three-layer structure.

FIG. 2 is a schematic diagram showing an embodiment of the present invention.

FIG. 3 is an explanatory view showing hollow moldings (a) to (c) each of which has two kinds of materials formed according to the present invention.

FIG. 4 is a schematic diagram showing another embodiment of the present invention.

5 is an explanatory view showing a modification of the embodiment shown in FIG.

[Explanation of Codes] 3 First extruder 4 Second extruder 6 Nozzle 7,18 First flow path 8,19 Second flow path 9,10 Shut-off valve 11 Control means 14-17 Engagement projection 20 Third Channel

Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location // B29C 49/22 9268-4F B29C 49/22 B29L 9:00 22:00

Claims (2)

[Claims] 1. A hollow molded article that is basically a single layer and is made of a resin material, and is connected to a first portion substantially made of a first resin material and the first portion via a boundary surface. And a second portion substantially consisting of a second resin material different from the first resin material, and gradually extending from the first resin material to the second resin material along the boundary surface. Hollow molded product characterized by changing. 2. The hollow molded article according to claim 1, wherein the boundary surface is substantially inclined with respect to at least one of an outer side and an inner side of the molded article.