JPH044120A - Fuel tank - Google Patents

Abstract

PURPOSE:To obtain a fuel tank where a transmission factor of gasoline fuel is low and manufacturing operation also is simple and safe, by a method wherein a material where sulphuric gas trioxide or fluorine is enclosed is formed between high-density polyethylene layers which are in a molten state. CONSTITUTION:Simultaneously with feed of high-density polyethylene which is made into a molten state by heating at the melting point or higher into extruding machines 1a, 1c sulphuric gas trioxide or fluorine is pressed into those through a cylinder 1d. Those materials each are extruded finally from a die 4 respectively through an annular path 2 and accumulator 3. A parison 5 in which the sulphuric gas trioxide or the fluorine is enclosed is obtained between high-density polyethylene layers which is in a molten state like this. Blow molding is performed within a mold by a normal method by making use of the parison 5 and a fuel tank is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a fuel tank for an automobile that is free from fuel leakage and easy to manufacture.

(Prior Art) Conventionally, single-layer tanks made of polyethylene have generally been used as fuel tanks for automobiles. The primary requirement for automobile fuel tanks is that there is no fuel leakage.

(Problems to be Solved by the Invention) A single-layer fuel tank made of polyethylene has a problem of high gasoline fuel permeability.

Therefore, in order to solve this problem, we took advantage of the property of polyamide with low Kalin permeability to blow a material consisting of a five-layer structure of polyethylene/adhesive/polyamide/adhesive/polyethylene obtained by a multilayer extrusion method. A multilayer fuel tank obtained by molding is used. However, in the case of this multilayer fuel tank, there is a problem that the impact strength of the polyamide is reduced due to the heat during extrusion molding, and the manufacturing cost is also high because polyamide is rather expensive.

There is also a single-layer polyethylene tank that is formed and reheated, and then sulfur trioxide gas or fluorine is blown into the tank to form a barrier layer for the gas on the tank surface. However, in the case of this tank, since it is necessary to reheat the tank after it has been formed, the manufacturing process becomes complicated and costs increase. There is also the problem of deterioration of the working environment due to leakage of unused gas out of the blown gas.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a fuel tank that has a low gasoline fuel permeability, is easy to manufacture, and is safe.

(Means and effects for solving the problems) In order to achieve the above object, the present invention is characterized in that it is made of a material in which sulfur trioxide gas or fluorine is sealed between layers of high-density polyethylene in a molten state. Provides fuel tanks for

The fuel tank of the present invention can be manufactured by blow molding using a sheet-like material, such as a parison, in which sulfur trioxide (SO3) scum or fluorine is sealed between layers of high-density polyethylene in a molten state.

The parison used in this method is made using a multilayer extrusion molding machine.
It is obtained by extrusion molding so that sulfur trioxide or fluorine is encapsulated between layers of high-density polyethylene in a molten state.

The sulfur trioxide gas or fluorine sealed here is preferably adjusted to a pressure in the range of about 0.9 to 1.1 atmospheres, which is the pressure at the time of sealing. Further, the amount of the gas to be sealed is not particularly limited, and it is preferable to use an amount such that a continuous phase of the gas is formed between the high-density polyethylene layers during the filling.

The fuel tank of the present invention can be obtained by blow molding in a conventional manner using a parison in which sulfur trioxide or fluorine is sealed between the molten high-density polyethylene layers thus obtained. The fuel tank of the present invention can also be blow-molded using a parison in which sulfur trioxide or fluorine is sealed between three or more layers of molten high-density polyethylene.

As described above, in the fuel tank of the present invention, the layer of sulfur trioxide gas or fluorine having the ability to suppress permeation of sulfur or the bonding layer of these scum and polyethylene is the high-density polyethylene layer forming the outer and inner surfaces of the tank. It is formed and maintained between

(Example) A fuel tank of the present invention was manufactured using a three-layer, three-layer accumulator head shown in FIG.

High-density polyethylene heated above its melting point to a molten state was supplied to the extruders 1a and 1c.

Then, instead of the extruder 1b, the extruder 1d was directly connected to a sulfur trioxide or fluorine bomb. Then two extruders 1
Molten high-density polyethylene was extruded from a and lc, and at the same time, sulfur trioxide gas or fluorine was injected into the hone from 1d. Each of these materials passes through an annular path 2 and an accumulator (ring chamber) 3, respectively, and is finally extruded from a die 4. In this way, a parison 5 was obtained in which sulfur trioxide gas or fluorine was sealed between the molten high-density polyethylene layers.

The pressure of sulfur dioxide gas or fluorine at the time of sealing was adjusted to about 1 atm.

Using this parison 5, blow molding was performed in a mold of a predetermined shape by a conventional method to obtain a fuel tank of the present invention. In addition, in the same way, with three types and five layers of accumulator head,
A parison was obtained by sealing sulfur trioxide gas or fluorine between three molten high-density polyethylene layers, and a fuel tank was blow-molded.

(Effects of the Invention) The fuel tank of the present invention is made of a material in which sulfur oxide gas or fluorine, which has the ability to suppress permeation of sulfur, is sealed between layers of high-density polyethylene in a molten state.

In this way, the outer and inner surfaces of the fuel tank are faced with high-density polyethylene, and the encapsulated sulfur trioxide or fluorine does not come into direct contact with the outside. Therefore, it is possible to reduce the Kallin transmittance.

Furthermore, sulfur trioxide gas or fluorine does not leak to the outside during operation, and manufacturing safety is high.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic partial sectional view of a three-layer three-layer accumulator head. ■... Three types of three-layer accumulator head, 1a... Extruder, 1b... Extruder, lc... Extruder, 1d...
- To gas cylinder, 2... Annular path, 3... Accumulator (link chamber), 4... Die, 5... Parison, 6... Hydraulic cylinder, 7... Ring plunger, 8...・Partition wall, 9...core.

Claims (1)

[Claims] A fuel tank characterized in that it is formed from a material in which sulfur trioxide gas or fluorine is sealed between layers of high-density polyethylene in a molten state.