JPS5850744Y2 - container - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydrocarbon-impermeable plastic container, particularly a plastic container useful as an automobile gasoline tank.

Traditionally, gasoline tanks in automobiles have been made of iron, but because they are made of iron, there is less freedom in tank design, which limits where the tank can be installed, which limits the effective use of the space in the automobile. It has been pointed out that there are disadvantages such as being easy to remove and being disadvantageous for weight reduction measures from an energy saving perspective.

Therefore, research has recently begun on the use of plastics that have arbitrary molding designs, are non-corrosive, are lightweight, and have high strength for gasoline tanks.

By the way, many plastics have the property of being permeable to gasoline vapors, so suitable plastics for gasoline containers include polyamide, which is impermeable to gasoline.
It is limited to plastics such as saponified ethylene vinyl acetate copolymer or polyethylene terephthalate.

However, these plastics are expensive, so the outer layer is made of polyolefin with excellent impact strength, only the inner layer is made of the above-mentioned gasoline-impermeable plastic, and a bonding agent is provided as an intermediate layer to fully bond both layers. was considered (for example, Japanese Patent Application Laid-Open No. 52-62574).

However, since the tank molded using this method is made up of three layers of three types of plastic with completely different coefficients of thermal expansion over the entire surface, thermal fluctuations will cause stress to occur across the interface between each layer. arise.

The first step in the generation of this stress is when the three types of molten plastic introduced into the mold are forcedly cooled and molded.

Next is the repeated thermal fluctuation after being installed in the car.

During the daytime in summer, when a car is outside, heat is transferred to the gasoline tank installed in a place that is not exposed to direct sunlight, and the temperature of the tank rises to a considerably high temperature. When a car cools down at night, its temperature drops, and it experiences several heat fluctuations throughout the day.

In addition, it is subject to thermal fluctuations that occur once a year due to temperature differences between summer and winter.

When such thermal fluctuations are repeated, cracks occur in the gasoline-impermeable inner layer, which has a lower heat shrinkage rate than the outer five layers of polyolefin, causing odor generation due to gasoline leakage.
There is a risk of a fire accident occurring.

The present invention aims to improve these drawbacks. Specifically, the present invention is a two-layer container consisting of an inner layer 1 made of a hydrocarbon-impermeable plastic and an outer layer 2 made of a plastic such as polyolefin, which forms the main body of the container. Several container components are welded together.

The term "container structure" as used herein refers to each part of a container divided into two, three, or more as appropriate.

When the method for joining the container structures is friction welding, it is preferable that the joined portion of the container structures be planar.

As shown in FIG. 1, the inner layer 1 and the outer layer 2 of the container structure a are mostly not joined, but the edge portions 4 and 5 of the inner layer and the outer layer are a partially joined body that is seamlessly provided. It is completely joined by 3.

Although it is preferable that no air exists between the inner layer 1 and the outer layer 2 in the unjoined portion, a small amount may be used as long as the amount of air does not destroy the bond between the inner layer 1 and the outer layer 2 due to expansion of the air. The presence of air is allowed.

In this way, the container of the present invention is a container in which the container structure a and other container structures having a similar structure are welded and integrated, as shown in FIG. 1, for example, and the inner layer 1 and the outer layer 2 and 2 are only partially joined and most of them are not, so when subjected to thermal fluctuations, both layers expand and contract separately, causing stress to occur at the interface between the two walls. It has the characteristic that there is no

As the plastic constituting the inner layer 1, any conventionally known hydrocarbon-impermeable plastics such as polyamide and saponified ethylene-vinyl acetate copolymer can be used.

Since the main purpose of the inner layer 1 is to inhibit the permeation of gasoline vapors within the container of the present invention, it is sufficient that the inner layer 1 has a thickness sufficient to achieve this purpose. It is usually in the range of 0.1 to 5 mm.

On the other hand, the outer layer 2 is mainly intended for the mechanical performance of the container of the present invention, such as impact resistance and pressure resistance, and its layer thickness is usually 1.5 to 4.5 mm. It is in the range of 0mm.

Examples of the plastic forming the outer layer 2 include polyolefins such as polyethylene and polypropylene.

Particularly preferred is ultra-high molecular weight polyethylene;
Polyethylene with added carbon black to improve weather resistance can also be preferably used.

Furthermore, the partial joining zone 3 is used to prevent the contents from entering between the inner layer 1 and the outer layer 2, and there are no particular restrictions on the shape or size, but it must be in an endless shape with no breaks at all. Requires.

Such a partially joined body 3 may be made of, for example, a modified polyolefin such as polyethylene or polypropylene modified with a polymerizable unsaturated carboxylic acid such as maleic acid or acrylic acid, or an inner layer 1 and an outer layer 2 such as an epoxy resin.
For both, materials with high adhesiveness are used.

Although various methods are possible for manufacturing the container of the present invention, injection molding is the most suitable method.

To explain such moldability, first, either the inner layer 1 or the outer layer 2 of the container structure obtained by dividing the container into two is preformed by injection molding, vacuum forming, or other moldability. The sheet is placed in the mold of an injection molding machine, and a bonding agent that is to become a film, sheet, or other appropriate shape of the partial bonding band 3 is fixed at the location where the partial bonding band 3 is to be provided. The molten plastic constituting the outer layer 2 or the inner layer 1 is injection molded and at the same time the bonding agent is melted to partially bond the inner layer 1 and the outer layer 2 only at their edges to obtain a container structure.

The container structure obtained in this way is separately molded with another container structure formed in the same manner using a friction wader, a high frequency welding machine,
After welding using other appropriate means or joining using an adhesive, a gasoline tank for an automobile or a hydrocarbon container is formed by performing secondary processing such as installing a conduit.

Furthermore, unless friction welding is used, the joints of the respective container structures preferably have concave, convex, or other shapes to facilitate mutual jointing, as shown in FIGS. 2A to 2C.

[Brief explanation of the drawing]

FIG. 1 shows a partially cutaway view of the container structure constituting the container of the present invention, and FIGS. 2A to 2C are cross-sectional views partially showing the shape of the joint of the container structure. Inner layer, 2 is outer layer, 3 is partial joined body, 4 and 5 are edge parts of inner layer and outer layer, a
, l) respectively indicate container structures.

Claims (1)

[Scope of utility model registration request] A two-layer hydrocarbon-impermeable container, the container comprising two or more container components welded together, each container component having an inner layer 1 of hydrocarbon-impermeable plastic.
and an outer layer 2 made of polyolefin, which are partially joined together by a continuous belt-like joining zone 3 along the edges of the inner layer and the outer layer.