JPH0562053B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an improvement in the method for manufacturing multilayer coextruded sheets or molded containers by coextrusion injection molding that require functionality.

Conventional technology Conventionally, this type of container has been manufactured using a molding method in which multiple types of resins are extruded from respective extrusion nozzles to form a multilayer extruded sheet, and the resulting sheet is formed by air pressure forming, vacuum forming, or a combination of both using air pressure forming and vacuum forming. It had been manufactured for some time. For example, the 6th
As shown in the figure, a five-layer coextruded sheet 53 of styrene-butadiene copolymer resin/adhesive resin/polypropylene/adhesive resin/styrene-butadiene copolymer resin is produced in a coextrusion process using extruders 51A to 51E. This coextruded sheet 53 was then subjected to a molding operation using male and female molds 55, 57 in container molding steps () to () to manufacture a plastic container 59. 60 is a cutting edge. In this operation, the desired effects were achieved on various physical properties such as oxygen permeability, water vapor permeability, various gas permeability, fragrance retention, light shielding properties, and heat resistance, depending on the characteristics and physical properties of each resin. .

However, when manufacturing coextruded sheets, the melting points of each resin may differ or they may be incompatible, and delamination may occur between the sheets, causing poor container molding, or it may be necessary to prevent delamination. Therefore, it is necessary to use a resin with an adhesive effect in the adhesive layer, which requires an extruder for the adhesive layer in addition to the number of layers actually required, making the equipment itself complicated and difficult to control.
It tended to become extremely difficult.

On the other hand, in the molding method using co-extruded sheets as raw materials, depending on the shape of the container, for example, for round containers, trimming loss around the outer periphery of the molding can account for 33 to 50% of the raw material sheet. However, because the removed scraps have different resin compositions with multiple layers, it is difficult to easily recycle and recycle them as sheet raw materials, unlike in the case of a single resin, and the removed scraps are generally so-called. , which had no choice but to become industrial waste and had already become a factor pushing up the cost of container products.

Problems to be Solved by the Invention The present invention involves extruding different types of resin in accordance with the desired purpose with a circular or square cross section that matches the shape of the molded container, cutting each resin into slices, and immediately before molding, the resin is cut into slices. A multi-layer co-extrusion device is created by combining several disc-shaped materials, crimping and fixing the edges of the multi-layered slices, and heating and molding to create a multi-layered container. The purpose of this is to provide a method that does not require the use of molding materials and does not generate scraps during molding.

In addition to crimping and fixing the edges of the slices and heat forming them, the bottom part can also be made stronger and more rigid by using methods such as high frequency, ultrasonic waves, and heat sealing. It is possible to equalize the non-uniformity of the shrinkage rate by using this method for the bottom portion, etc., and to manufacture a molded container with higher efficiency.

Means for Solving the Problems In order to achieve the above-mentioned object, the present invention provides a rod-shaped extrusion molded product made of a single resin of multiple types using an extrusion molding machine using multiple types of thermoplastic resins having different properties. The extrusion molded product is cut into slices of desired thickness using a cutter, and sliced circular plates made of various resins are combined according to the desired physical properties of the container, and the outer periphery of the slices is crimped and fixed. In this state, it is softened in a heating zone, and the softened portion is molded into the desired container shape in a desired manner to obtain a multilayer container.

The above resins suitable for the present invention include polypropylene, polystyrene, ethylene vinyl alcohol copolymer resin, polyethylene terephthalate, polyamide, polycarbonate, polyethylene, polyvinylidene chloride, ionomer resin, polybutylene terephthalate, polyvinyl chloride, and styrene butadiene copolymer resin. Examples include.

Furthermore, the molding method used in the present invention is as follows:
Any molding method depending on the shape, dimensions, etc. of the container can be used, such as pressure molding, vacuum molding, pressure vacuum molding, and blow molding.

Example In an extrusion molding machine 11 for thermoplastic resin equipped with a hopper 13 as shown in FIG.
Using a 120 mm extrusion die 17, extrusion products of each of styrene-butadiene copolymer resin, high-density polyethylene, ethylene-vinyl alcohol copolymer resin, and ethylene-vinyl copolymer resin are separately made into so-called round rods 19, that is, resin rods. Each of the round bars was cut using the cutter 21 to produce sliced circular plates of styrene-butadiene copolymer resin with a thickness of 0.3 mm, sliced circular plates of ethylene vinyl alcohol copolymer resin with the same thickness, and ethylene vinyl with the same thickness. Two sliced circular plates of high-density polyethylene having a thickness of 0.2 mm were prepared for each sliced circular plate of acetate copolymer resin. These sliced discs are designated by the reference numeral 23 in FIG. Next, these sliced circular plates 23 are superimposed to form a laminate 37 as shown in FIG.
It was created. That is, the laminate 37 includes a styrene-butadiene copolymer resin layer 31, a high-density polyethylene layer 32, and an ethylene-vinyl alcohol copolymer resin layer 3.
3. It consisted of a high-density polyethylene layer 34 and an ethylene vinyl acetate copolymer resin layer 35. The outer peripheral part (flange part) of the laminate 37 is fixedly crimped, and in that state, it is softened in a heating zone (heating furnace), and then molded into male and female molds 43 for pressure molding, vacuum molding, compressed air vacuum molding, or blow molding. , 45 (FIGS. 3 and 4). As a result, a multilayer container 47 shown in FIG. 5 was obtained.

Note that the extruder for thermoplastic resin, cutter (slicer), and molding machine for container molding used in this example are well-known per se.
The operating conditions are also well known and are described, for example, in the following documents:

“Packaging Technology Handbook” Published by Japan Packaging Technology Association 1969, September 15, 5th printing, pp. 1263-1267 Vacuum forming machine pp. 326-329 Molding processing effect of thermoplastic plastic Co-extrusion sheet molding using multiple sheet extruders To provide a method for manufacturing a multilayer composite resin molded container by creating a molded container by changing a die using a general-purpose extruder and using a slicer system without using any equipment, and without producing scraps. I was able to do it.

Styrene-butadiene copolymer resin / High-density polyethylene / Ethylene vinyl alcohol copolymer resin /
Containers with the composition of high-density polyethylene/ethylene vinyl acetate copolymer resin have the excellent printability of styrene-butadiene copolymer resin, the moisture-proofing properties of high-density polyethylene, the excellent oxygen shielding of ethylene-vinyl alcohol copolymer resin, and the advantages of storage materials, etc. It becomes possible to mold a container that has the easy-sealability and excellent heat-sealing strength of ethylene vinyl acetate copolymer resin, which is effective when heat-sealing. We also offer resin slices such as polypropylene, which has excellent moisture resistance, heat resistance, and oil resistance; polyvinylidene chloride and polycarbonate, which have excellent oxygen shielding properties and fragrance retention; polyamide, ionomer, and polyvinyl chloride, which have excellent impact strength; and polycarbonate, which has excellent rigidity. By combining them, it is possible to form a container that also has the above-mentioned multiple functions.

That is, in the present invention, the thickness of each layer can be set freely, and the materials of each layer can be freely combined in a structure of two or more layers according to functions such as barrier properties, adhesive properties, strength, and light blocking properties. be. Furthermore, slices can be made to match the shape of the molded product, which has the effect of eliminating molding loss.

[Brief explanation of the drawing]

Fig. 1 is a system diagram showing an extruder for thermoplastic resin and a state in which the rod-shaped resin extruded from the extruder is sliced into disk shapes by a cutter, and Fig. 2 is a system diagram showing the state in which the rod-shaped resin extruded from the extruder is sliced into disk shapes. A perspective view showing the state in which the sliced resin plates are stacked one on top of the other, FIG. 3 is a vertical cross-sectional view showing the state immediately before the sliced resin boards are superimposed on the molding machine, the sliced resin boards are installed, and molded, and FIG. 4 is the state immediately after molding. FIG. 5 is a vertical cross-sectional view of the product after molding, and FIG. 6 is a system diagram showing the conventional method. 11...Extrusion molding machine; 13...Hopper; 17
... Extrusion die; 19 ... Extrusion molded product; so-called round bar; 21 ... Cutter; 23 ... Sliced circular plate; 31 ... Styrene-butadiene copolymer resin layer;
32 and 34...high density polyethylene layer; 33
... Ethylene vinyl alcohol layer; 35 ... Ethylene vinyl acetate layer; 37 ... Laminate; 41
... Molding machine; 43, 45 ... Male and female molds; 47 ...
Multilayer container; 51A to 51E...Extruder; 53
... Coextrusion sheet; 55, 57 ... Male and female molds; 5
9... Container; 60... Cutting blade.

Claims (1)

[Claims] 1 Using multiple types of thermoplastic resins with different properties, an extrusion molding machine extrudes a rod-shaped extrusion molded product made of multiple types of single resin, and the extrusion molded product is sliced into arbitrary thickness using a cutter. The slices are cut, combined with sliced circular plates made of various resins according to the desired physical properties of the container, the outer periphery of the slices is crimped and fixed, and in that state is softened in a heating zone, and the softened portion is heated in a desired manner to the desired shape. A method for molding a multilayered container without trimming, characterized in that a multilayered container is obtained by molding the container into the shape of a container.