JPH0617031B2 - Method for producing multi-layered compression molded product - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a synthetic resin multi-layer compression molded product, which is advantageously embodied especially in a container or a container lid.

[Prior art]

Japanese Unexamined Patent Publication (Kokai) No. 62-184817 discloses a synthetic resin multi-layered compression molded article which is preferably embodied in a container or a container lid, and a method for producing the same. Such a multilayer structure compression molded product comprises an inner synthetic resin layer and an outer synthetic resin layer surrounding substantially the entire inner synthetic resin layer. The inner synthetic resin layer and the outer synthetic resin layer are made of different synthetic resins, for example, the inner synthetic resin layer is made of a synthetic resin having a high gas barrier property, and the outer synthetic resin layer is excellent in mechanical properties and hygiene. Made of synthetic resin. Such a multilayer structure compression molded product produces a composite synthetic resin material containing an inner synthetic resin layer and an outer synthetic resin layer surrounding substantially the entire inner synthetic resin layer, and the composite synthetic resin material is required. Manufactured by compression molding into shape.

[Problems of conventional technology]

The above-mentioned multilayer structure compression molded product is extremely useful especially as a container or a container lid, but there are the following problems in the manufacturing process thereof. That is, in the prior art, in order to manufacture the above-mentioned multilayer structure compression molded product, a composite synthetic resin material containing an inner synthetic resin layer, the inner synthetic resin layer, and an outer synthetic resin layer which substantially surrounds the whole is produced. It is necessary to. However, as disclosed in JP-A-62-184817, in order to produce a composite synthetic resin material in which the outer synthetic resin layer surrounds substantially the entire inner synthetic resin layer, the outer synthetic resin and the extruded resin are extruded. It is necessary to intermittently extrude and flow the inner synthetic resin into the flow channel, and for that purpose, an opening / closing valve mechanism for intermittently controlling the extrusion of the inner synthetic resin is required. Such an on-off valve mechanism is relatively complicated and expensive, and the on-off control of the on-off valve mechanism itself is not easy enough. Therefore, in the prior art, the production cost of the above-mentioned multilayer structure compression molded article was relatively high due to the fact that the production equipment was relatively expensive.

[Object of the Invention]

The present invention has been made in view of the above facts, and its main object is to provide a new and improved manufacturing method that enables a multilayer structure compression molded product having the required properties to be manufactured at a relatively low cost. Is to provide.

[Means for Solving the Invention and Action]

As a result of earnest research and experiments, the present inventors have shown that, instead of the composite synthetic resin material in which the outer synthetic resin layer substantially surrounds the entire inner synthetic resin layer, the outer synthetic resin layer is simply the inner synthetic resin layer. Even if a composite synthetic resin material that surrounds the side surface (thus, both end surfaces of the inner synthetic resin layer are at least partially exposed) is used, it is necessary to compress the composite synthetic resin material in the axial direction. It has been found that a multi-layered compression molded product having sufficiently satisfactory properties can be produced by compression molding into a shape.

That is, according to the present invention, a composite synthetic resin material containing an inner synthetic resin layer and an outer synthetic resin layer surrounding a side surface of the inner synthetic resin layer is produced, and the composite synthetic resin material is provided with an axial direction thereof. And a compression molding into a multilayer structure compression molded product having a required shape.

The composite synthetic resin material in a form in which the outer synthetic resin layer does not substantially surround the entire inner synthetic resin layer but simply surrounds the side surface,
For example, the inner synthetic resin layer and the outer synthetic resin layer are continuously passed through a composite extrusion channel including an inner synthetic resin layer extrusion channel and an outer synthetic resin layer extrusion channel surrounding the inner synthetic resin layer extrusion channel. It can be produced by extruding the composite resin and cutting the extruded composite synthetic resin transversely to the axial direction. Therefore, a relatively complex and expensive on-off valve mechanism for intermittent extrusion is not required, and a multi-layer structure compression molded product having the required characteristics can be manufactured considerably easily and inexpensively as compared with the conventional case.

[Preferred specific examples of the invention]

Hereinafter, preferred specific examples of the manufacturing method of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 schematically illustrates one mode of producing the composite synthetic resin material. The extruder 2 whose only extruding flow path end portion is shown includes an inner synthetic resin layer extruding flow path 4 and an outer synthetic resin layer extruding flow path 6 that surrounds the inner synthetic resin layer extruding flow path 4 coaxially. And a composite extrusion channel 8 composed of The outer synthetic resin layer extrusion channel 6 has an extrusion port 10 which may be circular. The inner synthetic resin layer extrusion channel 4 may also have a circular extrusion port 12
This extrusion port 12 has an outer synthetic resin extrusion channel 6 at a position somewhat upstream of the extrusion port 10 of the outer synthetic resin layer extrusion channel 6.
It has an opening inside. The inner synthetic resin layer 14 in a heated and melted state is continuously extruded through the inner synthetic resin extrusion channel 4,
Then, the outer synthetic resin layer 16 in a heated and melted state is continuously extruded through the outer synthetic resin layer extruding flow path 6, and thus the substantially cylindrical inner synthetic resin layer 14 and the inner synthetic resin layer 1 are formed.
A composite synthetic resin 18 containing a substantially cylindrical outer synthetic resin layer 16 that surrounds the peripheral side surface of No. 4 coaxially is extruded from the extruder 2. The extruded composite synthetic resin is moved transversely with respect to the axial direction (that is, the extruding direction) by a cutting means (not shown) which may be a rotary cutting blade, as shown by a two-dot chain line.
Preferably cut in a direction substantially perpendicular thereto,
Thus, the composite synthetic resin material 20 is produced.

The extruder 2 itself for producing the composite synthetic resin material 20 may be a known one, and therefore a detailed description of the extruder 2 will be omitted.

When the molded product that is compression molded as described below is a container or container lid for beverages, foods, etc., the inner synthetic resin layer 14 in the composite synthetic resin material 20 is made of a synthetic resin having a high gas barrier property, The outer synthetic resin layer 16 is conveniently made of a synthetic resin having excellent mechanical properties and hygiene. Examples of the synthetic resin having a high gas barrier property include olefin-vinyl alcohol copolymer resin, polyamide resin, high barrier polyester resin, nitrile resin, vinyl chloride resin and vinylidene chloride resin. Examples of the synthetic resin having excellent mechanical properties and hygiene include olefin resin, styrene resin, acrylic resin, methacrylic resin, polyester resin, and polycarbonate resin.

FIG. 2 schematically shows the container lid 22 as an example of the molded product. The container lid 22 has a circular top wall 24 and a cylindrical skirt wall 26 hanging from the peripheral edge of the top wall 24. As is well known, the inner peripheral surface of the skirt wall 26 may be formed with a female thread for screwing into a male thread formed on the outer peripheral surface of the neck of the container mouth, and also of the skirt wall 26. At the lower end, a so-called pill fur proof hem having a locking projection or a projecting piece for locking the locking jaw formed on the outer peripheral surface of the container neck is formed on the inner peripheral surface. (The female threads and pill fur proof hem are not shown for simplicity of drawing).

In the present invention, when the composite synthetic resin material 20 is compression-molded into the container lid 22, the composite synthetic resin agent 20
It is important to compress the resin in its axial direction (ie extrusion direction). 3A to 3D schematically show an example of the compression molding step of compression molding the composite synthetic resin material 20 into the container lid 22. The compression molding machine 28 has an upper female mold 30.
And a lower male mold 32. On the lower surface of the upper female die 30, a concave portion 34 defining a molding cavity is formed.
An expanded portion 36 is provided at the lower end of the recess 34 having a circular cross section. The lower male mold 32 includes a central member 38 and an annular outer member 40. The central member 38 has a cylindrical portion 42 extending upward. The cylindrical portion 4 of the central member 38
Two steps are formed in the annular outer member 40 arranged on the outer side of 2, and the upper end portion 44 and the intermediate portion 46 having a diameter slightly larger than this are present. The upper end 44 and the outer shape correspond to the inner diameter of the main portion of the recess 34 in the upper female die 30,
The outer shape of the intermediate portion 46 is the same as the concave portion 34 of the upper female die 30.
And the outer diameter of the expanded portion 36. The upper female die 30 and the lower male die 32 are relatively moved in a direction toward and away from each other by elevating and lowering the upper female die 30, for example. When starting compression molding,
As shown in FIG. A, the upper female die 30 is lifted and separated from the lower male die 32. Then, the composite synthetic resin material 20 is supplied to the central portion of the upper surface of the cylindrical portion 42 of the lower male mold 32. As described above, in the present invention, the composite synthetic resin material 2
It is important to compress 0 in the direction of its central axis, and therefore, the composite synthetic resin material 20 has its central axis extended in the direction of compression, that is, in the vertical direction in FIG. It is important to be supplied to the required position in.
Since the composite synthetic resin material 20 is in a molten state by heating, it is somewhat flowed and deformed from being extruded from the extruder 2 to being supplied to the compression molding machine 28 (hence shown in FIG. 3-A). The composite synthetic resin material 20 is somewhat flattened and spherical compared to the composite synthetic resin material 20 shown in FIG. Next, as shown in FIGS. 3-B to 3-D, the upper female die 30 is gradually lowered, and thus the composite synthetic resin material 20 is vertically moved between the upper female die 30 and the lower male die 32. Progressively compressed in a direction and flows along a molding cavity defined between the upper female die 30 and the lower male die 32. As can be seen by comparing and referring to FIGS. 3-B, 3-C and 3-D, during compression molding,
The upper surface portion and the lower surface portion of the composite synthetic resin material 20 come into contact with the upper female die 30 and the lower male die 32, respectively, and are cooled, so that the fluidity is relatively rapidly lowered, and therefore the material in the middle in the vertical direction is mainly compressed. It is appropriately fluidized according to. Thus, as clearly shown in FIG. 2, in the finally compression-molded container lid 22, the inner synthetic resin layer 14 extends substantially over the entire container lid 22 without being unevenly distributed in a specific portion. Before the compression molding, in the composite synthetic resin material 20, the inner synthetic resin layer 14 is not entirely surrounded by the outer synthetic resin layer 16, and the inner synthetic resin layer 14 is externally provided on the upper surface and the lower surface of the composite synthetic resin material 20. Is exposed to. Therefore, in the compression-molded container lid 22 as well, as shown in FIG. 2, the inner synthetic resin layer 14 is locally exposed to the outside at the inner and outer surfaces of the top wall 24 at the center. However,
Since the exposure of the inner synthetic resin layer 14 is limited to a remarkably small portion of the compressed surface, there is no possibility that a problem such as delamination between the inner synthetic resin layer 14 and the outer synthetic resin layer 16 may occur due to this. Virtually none.

If desired, when the composite synthetic resin material 20 is compression-molded, as shown by the two-dot chain line in FIGS. 2 and 3-A, the two ends of the composite synthetic resin material 20 (or one of them) It is also possible to dispose preformed covering members 48 and 50 so as to cover at least the boundary region between the inner synthetic resin layer 14 and the outer synthetic resin layer 16. Metal foil,
The covering members 48 and 50, which may be synthetic resin films, paper foils, or laminates thereof, can be positioned on the upper surface of the lower male mold 32 and the lower surface of the upper female mold 30 by any suitable method.

FIG. 4 illustrates a modification mode for producing the composite synthetic resin material. In this modified mode, the extruder 102, in which only the extruding flow path end portion is shown, has an inner synthetic resin layer extruding flow path 104 and an outer synthetic resin laminar flow that coaxially surrounds the inner synthetic resin layer extruding flow path 104. In addition to the channel 106, the central synthetic resin layer extrusion channel 103 is coaxially surrounded by the inner synthetic resin extrusion channel 104. The central synthetic resin extrusion channel 103 has an extrusion port 109 which may be circular, and this extrusion port 103 is the extrusion port 1 of the inner synthetic resin layer extrusion channel 104.
Somewhat upstream of 10, the inner synthetic resin layer extrusion channel 104
It has an opening inside. The central synthetic resin layer 113 in a heated and melted state is continuously extruded through the central synthetic resin extrusion channel 103, the inner synthetic resin layer 114 in a heated and molten state is continuously extruded through the inner synthetic resin extrusion channel 104, and the outside The outer synthetic resin layer 116 in a heated and melted state is continuously extruded through the synthetic resin layer extrusion channel 106, and thus the substantially cylindrical central synthetic resin layer 113 and the peripheral side surface of the central synthetic resin layer 113 are coaxially surrounded. A composite synthetic resin 118 including an inner synthetic resin layer 114 having a substantially cylindrical shape and an outer synthetic resin layer 116 having a substantially cylindrical shape surrounding a peripheral side surface of the inner synthetic resin layer 114 coaxially is extruded from the extruder 2.
The extruded composite synthetic resin is cut by a cutting means (not shown), which may be a rotary cutting blade, in a direction substantially perpendicular to the central axis direction (that is, the extruding direction) as shown by a two-dot chain line, thus The synthetic resin material 120 is generated.
The central synthetic resin layer 113 may be an appropriate synthetic resin different from both the inner synthetic resin layer 114 and the outer synthetic resin layer 116, or may be the same synthetic resin as the outer synthetic resin layer 116.

The extruder 1 for producing the composite synthetic resin material 120
02 itself may be well known, and therefore detailed description of the extruder 102 is omitted.

The three-layer composite synthetic resin material shown in FIG.
-A container lid 1 as shown in Fig. 5 in a manner substantially similar to that described with reference to Figures A to 3D.
22 can be compression molded. If desired, a composite synthetic resin material having a four-layer or more layer structure is produced, and the composite synthetic resin material is substantially the same as the method described with reference to FIGS. 3A to 3D. Depending on the method, the container lid 122 as shown in FIG. 5 can be compression molded.

The preferred embodiments of the present invention have been described above in detail with reference to the accompanying drawings. However, the present invention is not limited to such embodiments, and various modifications and alterations can be made without departing from the scope of the present invention. Of course, it is possible.

[Brief description of drawings]

FIG. 1 is a simplified cross-sectional view showing one mode of producing a composite synthetic resin material in a preferred specific example of the production method of the present invention. FIG. 2 is a simplified cross-sectional view showing a container lid manufactured in a preferred specific example of the manufacturing method of the present invention. 3A, FIG. 3B, FIG. 3C, and FIG. 3D show the container shown in FIG. 2 using the composite synthetic resin material produced by the method shown in FIG. FIG. 6 is a simplified partial cross-sectional view showing a step of compression-molding the lid. FIG. 4 is a simplified cross-sectional view showing a deformation mode for producing a composite synthetic resin material. FIG. 5 is a simplified cross-sectional view showing a container lid manufactured by compression molding the composite synthetic resin material shown in FIG. 2 ... Extruder 103 ... Central synthetic resin layer extrusion channel 4 and 104 ... Inner synthetic resin extrusion channel 6 and 106 ... Outer synthetic resin extrusion channel 113 ... Central synthetic resin layer 14 and 114 ... Inside Synthetic resin layer 16 and 116 ... Outer synthetic resin layer 20 and 120 ... Composite synthetic resin material 22 and 122 ... Container lid 28 ... Compression molding machine 30 ... Upper female mold 32 ... Lower male mold 48 and 50 ...... Coating members

Claims (5)

[Claims] 1. A method for producing a composite synthetic resin material containing an inner synthetic resin layer and an outer synthetic resin layer surrounding side surfaces of the inner synthetic resin layer, and compressing the composite synthetic resin material in its axial direction. And a compression molding into a multilayer structure compression molding having a required shape. 2. An inner synthetic resin layer and an outer synthetic resin layer are passed through a composite extrusion channel including an inner synthetic resin layer extrusion channel and an outer synthetic resin layer extrusion channel surrounding the inner synthetic resin layer extrusion channel. The method for producing a composite synthetic resin material according to claim 1, wherein the composite synthetic resin material is produced by continuously extruding the mixture and cutting the extruded composite synthetic resin in a direction transverse to the axial direction. 3. The manufacturing method according to claim 1, wherein the inner synthetic resin layer in the composite synthetic resin material has a substantially cylindrical shape, and the outer synthetic resin layer has a substantially cylindrical shape. 4. An inner synthetic resin layer and an outer synthetic resin layer of the composite synthetic resin material are both substantially cylindrical in shape, and the composite synthetic resin material is a substantially cylindrical central composite surrounded by the inner synthetic resin layer. The manufacturing method according to any one of claims 1 to 3, which is also contained in the resin layer. 5. The in-mold molding is performed by disposing at least one of both end faces of the composite synthetic resin material with a covering member that covers at least a boundary region between the inner synthetic resin layer and the outer synthetic resin layer. The manufacturing method according to any one of 1 to 4.