JPS6222866B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a large container having excellent chemical resistance and gas barrier properties and extremely high strength, which is made by welding a container structure consisting of two or three layers. Already, large containers with excellent chemical resistance, gas barrier properties, and strength have been produced using polyolefin with a molecular weight of 250,000 or more as the main layer, and polyamide resin as an inner layer to provide chemical resistance and barrier properties. Containers have been proposed that use an unsaturated carboxylic acid-modified polyolefin as an intermediate layer for bonding two layers together. The above-mentioned method of manufacturing the proposed container was to mold a multilayer parison using an extruder, and then mold the parison using a blow molding machine. However, blow molding is effective when the container has a relatively simple shape and the raw material resin is relatively fluid, but when the container has a complex shape and When a resin with poor fluidity is used, it is difficult to obtain a molded product according to the designed mold, such as a thin part that is less than the designed thickness. In particular, the design thickness of the polyamide resin layer, which is provided for the purpose of imparting chemical resistance and gas barrier properties, should be made as thin as possible because the resin is expensive and even a thin layer can exhibit sufficient effects. However, it is extremely difficult to mold this thin layer to a uniform thickness using blow molding. Furthermore, in blow-molded containers, a structure is used in which a baffle plate is inserted into the container, which has the effect of preventing the generation of liquid wave noise and reducing the collapse of the container when the liquid storage container vibrates. Unable to hire. Furthermore, the rotational molding method requires a long molding cycle, making it difficult to form a thin layer. The present invention has been made in view of the above points, and consists of dividing a container into two or more container components, injection molding each container component, and then welding each container component using a high-frequency welding machine. Alternatively, it is basically integrated into a container using a friction welder. More specifically, in the present invention, the outer layer of the container structure, which constitutes the main body of the container, is made of injection molded high-density polyethylene (hereinafter referred to as HDPE) or ultra-high molecular weight high-density polyethylene (hereinafter referred to as EHDPE) with a molecular weight of 80,000 or more. It shall be. A method for laminating an inner layer inside the outer layer of the container structure to improve the chemical resistance and gas barrier properties of the container is as follows. A chemical-resistant, gas-barrier sheet made of nylon 6 or 11 is processed using a vacuum forming machine or a pressure forming machine.
The pre-molded sheet is molded to match the shape of the inner wall of the container structure, and the pre-molded sheet is attached to the male mold (core) of an injection molding machine, and then HDPE or EHDPE is injected so that the outer layer is HDPE or EHDPE and the inner layer is nylon. A container construction is obtained which is a barrier layer such as. When trying to improve the adhesion between HDPE or EHDPE and nylon, form a sheet in which unsaturated carboxylic acid-modified polyethylene is laminated in advance on a nylon sheet in the same manner as above, and the modified polyethylene layer becomes an intermediate layer. It can be used. A container structure consisting of two or three layers formed by appropriately adopting the method described above is then welded at the joint surface of each container structure using a friction welding machine or a high-frequency welding machine to form an integrated large-sized container structure. It is considered a container. By installing an appropriately shaped baffle plate or the like inside the container structure prior to welding the container structure, it is possible to create a container that achieves the above-mentioned effect by inserting the baffle plate or other structure into the container. . In addition to the above-mentioned nylon, saponified ethylene vinyl acetate copolymer (EVOH) and other resins with excellent chemical resistance and gas barrier properties can be used as appropriate materials for the inner layer with gas barrier properties. I can do it. The container of the present invention has the above-mentioned structure, and is capable of easily and accurately molding a container with a complicated shape, can reliably provide sufficient strength, chemical resistance, and gas barrier properties, and is furthermore capable of being easily molded with high precision. Because plates can be inserted, it is extremely suitable for automobile fuel tanks, especially passenger automobile gasoline tanks.
It also has great utility as a container for transporting and storing various oils, chemicals, poisonous substances, etc. Examples will be described below. Example A sheet of nylon-11 (Rilsan manufactured by Aquitaine Colganico) or EVOH (EVAL manufactured by Kuraray) laminated with unsaturated carboxylic acid-modified polyethylene is formed into a shape that matches the shape of the inner wall of the container structure using a pressure forming machine. A pre-formed sheet was obtained. This was applied to the male mold of an injection molding machine so that an unsaturated carboxylic acid-modified polyethylene layer became an intermediate layer, and then ultra-high molecular weight high-density polyethylene (SHOREX 4551H manufactured by Showa Yuka Co., Ltd.) was injected. Outer layer (3 mm) made of high molecular weight high density polyethylene, middle layer (0.1 mm) made of unsaturated carboxylic acid modified polyethylene
mm), inner layer made of nylon-11 or EVOH (0.1
Table 1 shows the measurement results of the amount of gasoline permeation for a container obtained by molding a three-layer container structure (mm) and integrating each container structure using a friction welding machine. The various conditions are as follows. [Molding] Injection molding machine Mitsubishi Natco 400 tons Cylinder temperature Front 270℃ Middle 255℃ Rear 240℃ Injection pressure High pressure 145Kg/cm ² Holding pressure 130Kg/cm ² Screw rotation speed 39r・p・m Welding machine Friction Welder Molded container capacity 500 c.c. [Gas permeation amount measurement] Measuring method: Fill the container with gasoline, measure the weight, and after leaving it for one day, measure the weight, calculate the total permeation amount, and calculate the permeation amount. is divided by the surface area of the container and expressed as the amount of permeation per 1 cm ² per day. Room temperature is 40℃
I did it at

【table】

[Table] A friction welding strength test was conducted on the molded containers. Welding conditions Air pressure 6.0Kg/cm ² Welding time 6.0sec Welding width 3.0mm Weld width 4mm (1) Water pressure test...High pressure water is injected into the container using a water pressure machine, and the fracture strength of the weld is tested. Measure. Results: There was no water leakage from the welding part within 8Kg/cm ² (gauge pressure) (beyond this, the stopper would come off and measurement would not be possible) (2) Drop impact test...The container was filled with water and sealed. , the welded part was dropped onto a flat concrete surface. Results 2m or less No cracks 2-3m 1 part crack (3) Tensile strength test... Width 25mm centered on the welded area
A sample was collected using an Autograph IS-5000 manufactured by Shimadzu Corporation.
At room temperature 20℃, tensile speed
Measured at 10mm/min. Result: 240-260Kg/ ^cm2 , almost the same strength as the raw base material. [Raw base material 290Kg/ ^cm2 ]

Claims (1)

[Claims] 1. A pre-formed sheet made by molding a sheet of resin with high chemical resistance and gas barrier properties, with or without lamination of unsaturated carboxylic acid-modified polyolefin, to match the shape of the inner wall of the container structure. A high molecular weight or ultra high molecular weight polyolefin resin that is coated on a mold and then laminated with a resin with high chemical resistance and gas barrier properties on the inside obtained by injection molding a high molecular weight or ultra high molecular weight polyolefin resin. A large, strong container whose container components are integrated by high-frequency welding or friction welding.