JPH054274A - Forming method of thermoplastic resin sheet - Google Patents

Abstract

PURPOSE:To obtain a formed article, the sheet stocks of which are different from each other locally, by a method wherein thermoplastic resin sheets, at least one of which is made so as to have the width narrower than the width of hot glued laminated sheet, are employed so as to hot glue two or more sheets under the condition that one of their side edges is put upon the other. CONSTITUTION:Two different sheets S and H are fed parallel to a forming device by passing through a guide 20 arranged to a trestle. Both the respective widths W1 and W2 of tire sheets S and H are made to be narrower than the width W of the hot glued sheet. The forming device carries both the sheets S and H under the condition that only both their sides are clamped to a heating section 50 and a forming section. The central part of the sheets are locally hot glued with a heat sealer 42 so as to be made into an integral body and carried. After that, the laminated sheet is pressed with hot plates 52 and 52' and formed with molds 52 and 62'. When a container is formed at a forming section 60, the container main body side is made of the sheet S and the cover side is made of the sheet H. Thus, laminated sheet, the necessary portion of which can show proper function, can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for molding a thermoplastic resin sheet, and more particularly to a method for molding a plurality of different sheets after laminating them by thermal bonding.

[0002]

PRIOR ART AND PROBLEM TO BE SOLVED BY THE INVENTION Heretofore, in the case of laminating two or more kinds of thermoplastic resin sheets, a composite sheet is formed by extrusion lamination, hot roll lamination, composite extrusion or the like, and then an oven is used. A method of heating and softening by heating and then molding is adopted. However, in each of the above methods, a process for compounding is required, and in addition to lack of support for small lots and a wide variety of products,
The same composite structure must be adopted for the part of the container that does not need to be composited for the purpose of overall composition.

In recent years, as a packaging container molded from a thermoplastic resin sheet, a container with a hinge in which a main body (body) of the container and a lid are integrated is often used. This is an important factor for rationalization in filling the packaged item in the container. However, in general, the body side is strong,
The actual situation is that the lid side needs to be transparent and does not require so high strength. When considering these points, the foamable thermoplastic resin sheet is suitable for the main body side in terms of strength, but is too strong for the lid body, and the contents cannot be seen from the outside. On the contrary, if the main body is made of a non-foamed sheet, it is weak, and if the sheet thickness is increased to make it strong, it becomes expensive, and the lid is too thick and strong, and the transparency of the contents is reduced.

Therefore, until now, the main body and the lid have been separately molded, and the hinge portion has been integrated by heat bonding in a separate process, or staples or tapes have been used, but this requires a lot of processing man-hours and costs. It was high. Therefore, in order to solve the above-mentioned problems in the present invention, for example, focusing on the fact that it is desirable that the main body of the container and the lid body are simultaneously molded from different materials, and particularly using partially different materials. so,
The purpose is to give the required function to the necessary parts, to suppress the excessive quality of the molded product, to help reduce the weight, and to obtain the molded product at a low cost with the minimum functions.

[0005]

A method for forming a thermoplastic resin sheet of the present invention which can solve the above-mentioned problems of the prior art is as follows. In the method of forming a desired shape after partially heat-bonding with a hot plate of No. 1, at least one of the two or more kinds of thermoplastic resin sheets to be heat-bonded is It is characterized in that a sheet formed to have a width narrower than the width of the laminated sheet is used and at least side edges of two or more types of sheets are overlapped and heat-bonded.

[0006]

In the molding method of the present invention having the above-mentioned structure, at least one of the thermoplastic resin sheets is slit to a width narrower than the width of the laminated sheet after heat bonding, so that two or more types of sheets can be used. If at least the side edges are overlapped and heat-bonded, the part of the heat-bonded laminated sheet that uses the slitted sheet and the other part will be in a different state, so take advantage of the characteristics of different states in molding. It is possible to obtain a molded product having a partially different sheet material.

[0007]

EXAMPLE Next, referring to the drawings, an example of the present invention will be described.
Explained below. In the case shown in FIG. 1 and FIG.
Len sheet S and high-impact polystyrene sheet H
The sheet width is narrower than the sheet width W after heat bonding.
Width W ₁, W₂The method using the one formed in
is doing. In the figure, 10 supplies a polystyrene sheet S
Material supply unit, 20 is a guide, 30 is high impact poly
An original fabric supply section for supplying the styrene sheet H, and 40 is a heating power source.
A preheater with a heat sealer 42 having a source 41, 50 is a shield
By the hot plates 52, 52 'having the binder mechanisms 51, 51'
Heating unit, 60 is a metal having a cylinder mechanism 61, 61 '
The forming part by the molds 62 and 62 'is shown.

The positions of the two types of sheets shown in the figure are determined through a guide 20 installed on a pedestal so that the sheets can be fed in parallel to the molding apparatus. The forming device can clamp both sides of the sheet and convey them to the heating unit 50 and the forming unit 60. However, since the sheet located in the central portion that cannot be clamped by the clamp cannot be conveyed as it is, Is provided with a heat sealer 42 that operates at each feeding pitch, and can be integrally conveyed by being partially heat-bonded.

However, the heat sealer is not essential,
If it can be manually transferred to the hot plate located in the heating part, the thermal bonding by the hot plate can play the same role as the above heat sealer. In particular, in the case of FIG. 1, the high-impact polystyrene sheet H is arranged at the center and the expanded polystyrene sheets S are arranged on both sides, and in the case of FIG. On the other hand, a high-impact polystyrene sheet H is laminated, and only the high-impact polystyrene sheet H is arranged at the center and two layers are laminated on both sides.

In the case of FIG. 1, as shown in FIG.
It is pressed at 52 ', and this is the mold 62,6
When molded by 2 ', it becomes as shown in FIG. 4, and in the case of FIG. 2, it is pressed by the hot plates 52, 52 as shown in FIG. 5, and when it is molded by the molds 62, 62, it becomes as shown in FIG. become. Further, in the case where the molding part 60 by the molds 62 and 62 'molds a container, the main body side A of the container is made of the expanded polystyrene sheet S and the lid side B is made of the transparent high-impact polystyrene sheet H of FIG. Such a container molded product or a container molded product as shown in FIGS. 8 and 9 in which the main body side has two layers and the lid side has one layer.

In practice, the pair of upper and lower hot plates have an area larger than the outer dimension by about 3 to 6 mm than the area required to be formed, and have a pressing force of 0.3 to 1.2 kg / cm ^2. Hold the sheet under pressure to heat bond and soften it at the same time. The temperature of the hot plate is set so that the surface temperature is 140 to 180 ° C., and is adjusted according to the material to be heated and the heating time.

Further, since the total thickness of the sheet differs between the composited portion and the non-composited portion, the clearance of the hot plate is set according to the thickness. As a press device for keeping this clearance constant, various known measures such as a hydraulic cylinder and a toggle press can be used, but it is necessary to keep it as constant as possible.
Excessive pressurization, especially in the case of a foamed sheet, causes destruction of the foamed layer. Therefore, it is generally necessary to set the clearance of the hot plate at the time of pressurization to about 60% of the sheet thickness. It is used by cutting necessary places so that this clearance can be maintained.

In practice, the forming section is a vacuum method,
Molding can be performed without change from molding by a conventional oven heating method such as a plug assist method or a match molding method. As the thermoplastic resin sheet, a foamed sheet, a non-foamed sheet, or a film of a thermoplastic resin such as polystyrene, polyethylene, polypropylene, polyethylene terephthalate, polymethylmethacrylate, or polymethylpentene is used.

Specific Example of Implementation Case shown in FIG. 1 Original polystyrene foam sheet Thickness 1.8 mm Basis weight 157 g / m ² Width 640 mm High-impact polystyrene sheet Thickness 0.2 mm Width 160 mm Hot plate temperature 145 to 150 ° C. Heating time 4. 0 seconds Molding cycle 5.2 seconds / shot Molding method Plug-assisted vacuum method Molded product size In FIG. 7, e: 265 mm f: 175 mm t: 37 mm

[0015]

According to the molding method of the present invention, it is possible to provide a laminated sheet which can exhibit a function suitable for a required place by using partially different material sheets. Taking a packaging container as an example of a molded product from a laminated sheet, the main body and the lid can be molded with different sheet configurations.

Moreover, in the present invention, since lamination can be performed at the same time as molding, the laminating step can be omitted, and the combination of materials can be easily changed, which is highly adaptable to the production of various kinds.

[Brief description of drawings]

FIG. 1 (a) is a plan view showing an execution device and a seat,
(b) is a front view of (a) above.

FIG. 2 (a) is a plan view of an embodying apparatus and a seat showing a modified example, and FIG. 2 (b) is a front view of the same (a).

FIG. 3 is a schematic side view of a sheet pressed by a hot plate.

FIG. 4 is a schematic cross-sectional view of a state where a sheet is molded.

FIG. 5 is a schematic cross-sectional view showing a pressed state by a hot plate showing a modified example.

6 is a schematic cross-sectional view of a molded container product from that of FIG.

FIG. 7 (a) is a plan view of a molded container product with a transparent lid, (b)
Is a schematic sectional view.

FIG. 8A is a plan view of a container molded product having two layers on the main body side and one layer on the lid side, and FIG. 8B is a schematic sectional view.

9A is a plan view of a container molded product in which the sheet is reversed from FIG. 8, and FIG. 9B is a schematic sectional view.

[Explanation of symbols]

S Expanded polystyrene sheet H High-impact polystyrene sheet 10,30 Raw material supply part 20 Guide part 40 Preheating part 50 Heating part 60 Forming part W Sheet width after thermal bonding W ₁ , W ₂ Narrow sheet width

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location B29L 22:00 4F

Claims (1)

Claims: 1. At least two or more kinds of thermoplastic resin sheets are continuously superposed and supplied, partially heat-bonded by a pair of upper and lower heat plates, and heat-softened, and then desired. In the method for forming a shape, at least one of the two or more types of thermoplastic resin sheets to be heat-bonded is formed to have a width narrower than the width of the laminated sheet after heat-bonding, and two or more types are used. A method for molding a thermoplastic resin sheet, characterized in that at least side edges of the sheet are overlapped and heat-bonded.