Pipes and tubular conduits – Flexible – Distinct layers
Reexamination Certificate
2000-08-31
2001-08-28
Brinson, Patrick (Department: 3752)
Pipes and tubular conduits
Flexible
Distinct layers
C138S140000, C138S141000, C138SDIG007
Reexamination Certificate
active
06279615
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention concerns a fuel hose mainly used for automobiles. More particularly, this invention relates to a fuel hose showing excellent impermeability to alcohol-mixed gasoline where methanol, ethanol, or the like is mixed. The fuel hose of this invention can also be used suitably as a pipeline for an alcohol fuel cell or a hydrogen fuel cell, for example, in automobiles.
2. Description of the Related Art
In recent years, there has been a demand for decreasing atmospheric release of gasoline in view of environmental problems. Therefore, regulations against permeation of gasoline have become more and more severe for fuel hoses for use in automobiles. Conventional single layered hoses composed of NBR/PVC cannot satisfy such regulations sufficiently.
In view of the above, it has been considered to provide a thin film of a resin layer on the innermost layer of a fuel hose. Resin materials have higher impermeability to gasoline than rubber materials. Further, when the resin layer is formed of a thin film, the flexibility of the fuel hose can be maintained. Specifically, it has been proposed to provide a thin film polyamide resin layer or a thin film fluororesin layer on the innermost layer of a fuel hose.
For instance, Japanese Patent Application Laid-Open No. 118549/1996 discloses laminating a tubular body of unvulcanized rubber of epichlorohydrin and an extruded fluororesin layer and adhering them by vulcanization. Japanese Patent Application Laid-Open No. 255004/1994 discloses electrostatically coating a powdery fluororesin to the inner circumferential surface of a tubular body of vulcanized rubber and then forming a fluororesin layer by heating and cooling. In the fuel hoses described above, more excellent impermeability than that of a single layered rubber hose can be expected for ordinary gasoline.
Recently, in view of the toxicity of MTBE (methyl tert-butyl ether) added to gasoline as an octane number improver, attention has been paid to the change to an alcohol-mixed gasoline. However, the alcohol-mixed gasoline has a rather high gasoline permeability not only to rubber materials, but also to resin materials. The reason is probably that when alcohol having low molecular weight selectively permeates, gasoline induced by the alcohol also permeates, resulting in the high gasoline permeability.
According to studies by the inventors, when a polyamide resin layer or a fluororesin layer is formed on the innermost layer, it is not easy to reduce the film thickness of the resin so as to ensure required flexibility of a fuel hose while simultaneously ensuring the sufficient impermeability to the alcohol-mixed gasoline.
In view of the regulations against fuel permeation expected to be enforced from the year of 2004 in the United States, there has been a strong demand for a fuel hose capable of conforming to severe regulations for impermeability to gasoline including alcohol-mixed gasoline.
SUMMARY OF THE INVENTION
Accordingly, an object of this invention is to provide a fuel hose having a thin film resin layer on the inner circumferential surface of a tubular rubber body, which can maintain necessary flexibility and show excellent impermeability to ordinary gasoline and alcohol-mixed gasoline.
Another object of this invention is to attain the foregoing object by improving a relatively rigid ethylene-vinyl alcohol copolymer into a soft structure and using the same as a material for the thin film resin layer.
A further object of this invention is to attain the foregoing object by improving a relatively rigid polybutylene aromatic ester resin into a soft structure and using the same as a material for the thin film resin layer.
A first aspect of this invention resides in a fuel hose comprising a single layered or multi-layered tubular rubber body and a thin film resin layer formed on the inner circumferential surface of the innermost layer of the tubular rubber body, wherein the resin layer is formed of a resin such that an amount of permeation of 10% ethanol-mixed gasoline is 2 mg/cm
2
/day (at 60° C.) or less when the thickness of the resin layer is 0.1 mm.
The fuel hose according to the first aspect can provide both a satisfactory impermeability to an alcohol-mixed gasoline and a satisfactory hose flexibility owing to the thin film structure of the resin layer.
A second aspect of this invention resides in a fuel hose comprising a single layered or multi-layered tubular rubber body and a thin film resin layer formed on the inner circumferential surface of the innermost layer of the tubular rubber body, wherein the resin layer is formed of EVOH (ethylene-vinyl alcohol copolymer) with an ethylene content of 30 to 50 mol %.
It has been found that EVOH shows excellent gasoline-impermeability comparable with that of a fluororesin to ordinary gasoline and alcohol-mixed gasoline. In addition, the flexibility can be controlled by increasing or decreasing the ethylene content in EVOH.
In the second aspect, since the ethylene content of EVOH is defined within a range from 30 to 50 mol %, the flexibility of the resin layer and the gasoline impermeability are compatible in a well-balanced manner. Therefore, even when the resin layer is formed into such a thin film as not to deteriorate the flexibility of the hose, the impermeability to gasoline including alcohol-mixed gasoline is favorable. There will be a problem in the flexibility of the fuel hose if the ethylene content in EVOH is less than 30 mol % and in the impermeability to gasoline including alcohol-mixed gasoline if the ethylene content exceeds 50%.
A third aspect of this invention resides in a fuel hose comprising a single layered or multi-layered tubular rubber body and a thin film resin layer formed on the inner circumferential surface of the innermost layer of the tubular rubber body, wherein the resin layer is formed of a polybutylene aromatic ester.
It has been found that the polybutylene aromatic ester shows excellent impermeability to gasoline comparable with that of the fluororesin to ordinary gasoline and alcohol-mixed gasoline. In the third aspect of the invention, since the thin film resin layer is formed of a polybutylene aromatic ester, the flexibility required for the fuel hose can be ensured and the impermeability to gasoline including alcohol-mixed gasoline is favorable.
The above and other advantages of the invention will become more apparent from the following description and the accompanying drawings.
REFERENCES:
patent: 5469892 (1995-11-01), Noone et al.
patent: 5488975 (1996-02-01), Chiles et al.
patent: 5560398 (1996-10-01), Pfleger
patent: 5588468 (1996-12-01), Pfleger
patent: 6089278 (2000-07-01), Nishino et al.
patent: 6170535 (2001-01-01), Sadr et al.
patent: 6194040 (2001-02-01), Delius et al.
patent: 5-44874 (1993-02-01), None
patent: 5-164273 (1993-06-01), None
patent: 6-33031 (1994-02-01), None
patent: 6-99548 (1994-04-01), None
patent: 6-255004 (1994-09-01), None
patent: 93/25835 (1993-12-01), None
patent: 95/30105 (1995-11-01), None
Iio Shinji
Ito Hiroaki
Nishiyama Takahiro
Brinson Patrick
Jacobson & Holman PLLC
Tokai Rubber Industries Ltd.
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