Stock material or miscellaneous articles – Hollow or container type article – Polymer or resin containing
Reexamination Certificate
1999-11-12
2003-06-10
Nolan, Sandra M. (Department: 1772)
Stock material or miscellaneous articles
Hollow or container type article
Polymer or resin containing
C138S137000, C138S138000, C428S036600, C428S216000, C428S474900, C428S475800, C428S476100, C428S480000, C428S483000
Reexamination Certificate
active
06576312
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a fuel transporting tube and particularly to such a tube which has a laminated structure including a plurality of layers, which exhibits an excellent resistance to permeation of fuels, e.g., not only gasoline but also alcohol-blended gasoline, an excellent detergent resistance, and an excellent hydrolysis-deterioration resistance, and exhibits an excellent resistance to interlayer separation when being used in a high-temperature atmosphere, and which is particularly suitable for use in a fuel-transporting piping system of an automotive vehicle.
2. Related Art Statement
A fuel-transporting piping system of an automotive vehicle includes a feed tube, a return tube, an evaporator hose, a breather hose, a filler hose, an ORVR-tube, or the like. Conventionally, various sorts of metallic, rubber, or resinous tubes or hoses have been used in the piping system. Recently, resinous tubes are widely used in consideration of cost performance, in particular. Meanwhile, national regulations regarding fuel evaporative emission have been stricter and stricter in consideration of environmental problems. That is, it is strongly desired to minimize the amount of fuel that permeates through the tubes and transpires into the atmosphere.
In United States of America, alcohol-blended gasoline is commercially used as a fuel of automotive vehicles. Generally, the amount of alcohol-blended gasoline that permeates out through a resinous or rubber tube is much more than that of non-blended gasoline that does not contain alcohol. Thus, it is desired to develop a tube which has an excellent resistance to permeation of not only non-blended gasoline but also alcohol-blended gasoline.
Various proposals have been made in the above-indicated background. For example, Japanese Patent Document TOKU-KAI-HEI No. 4(1992)-224384 discloses a fuel transporting tube including, as its fuel barrier layer, an innermost layer which is formed of a polyester resin such as polyethylene terephthalate or polybutylene terephthalate, and U.S. Pat. No. 5,425,817 discloses a multi-layer plastic tube including an innermost layer and an outermost layer each of which is formed of a polyamide, and including, as a low-permeation layer, an intermediate layer which is formed of a linear-crystalline polyester such as polyethylene terephthalate or polybutylene terephthalate. In addition, Japanese Pat. Document TOKU-KAI-HEI No. 6(1994)-23930 discloses a multi-layer polymer hose or pipe including an innermost layer and an outermost layer each of which is formed of a polyamide, and including, as a low-permeation layer, an intermediate layer which is formed of a polyester resin such as polyethylene terephthalate, polybutylene terephthalate, or polyethylene naphthalate, and European Patent Application No. 0686797 A1 discloses a multi-layer plastic tube including, as a low-permeation layer, an innermost layer which is formed of a thermoplastic polyester such as polyethylene terephthalate or polybutylene terephthalate.
However, even the above-indicated multi-layer or laminated tubes that are claimed to be resistant to permeation of alcohol-blended gasoline, do not satisfactorily meet the currently desired, very strict requirement regarding the resistance to permeation of alcohol-blended gasoline, even if those resins disclosed in the prior documents may be selected anyway.
Out of the above-indicated tubes, ones whose innermost layer is formed of polyethylene terephthalate or polybutylene terephthalate are deteriorated, during a long period of use, because of an amine detergent that is usually added to a fuel for the purpose of removing stains of an intake valve. That is, those tubes do not exhibit a sufficiently high detergent resistance. In addition, tubes whose innermost layer is formed of one of the resins disclosed in the prior documents do not exhibit a sufficiently high resistance to hydrolysis of innermost layer. More specifically described, the innermost layer may be hydrolyzed because of water contained in the fuel, or moisture present in the atmosphere. Therefore, those tubes do not exhibit a sufficiently high reliability when being used as fuel transporting tubes for a long period in a high-temperature atmosphere.
Moreover, in the case where the low-permeation layers are used as not the respective innermost layers of tubes but the respective intermediate layers thereof, the intermediate layers may peel or separate from respective layers- provided radially inwardly of the intermediate layers, in particular when being used in a high-temperature atmosphere. Thus, the tubes including, as their intermediate layers, the low-permeation layers do not exhibit a sufficiently high reliability.
By the way, Japanese Patent Document TOKU-KAI-HEI No. 7(1995)-96564 discloses a fuel transporting tube which is claimed to be able to be used as a low-permeation or anti-permeation layer against alcohol-blended gasoline, and which includes, as an anti-permeation layer, an intermediate layer formed of a polyalkylene naphthalate resin, such as polybutylene naphthalate, that exhibits a higher permeation resistance than a polyester resin, such as polybutylene terephthalate, and additionally includes an innermost layer which is formed of a fluororesin or a polyamide. Since the fuel transporting tube has a laminated structure including the above-indicated resinous innermost layer, the anti-permeation intermediate layer may separate from the innermost layer located inside the intermediate layer, because of the fuel which permeates out through the innermost layer, though an adhesive layer is provided between the intermediate layer and the innermost layer. Thus, the tube does not exhibit a sufficiently high reliability.
In particular, since the innermost layer formed of fluororesin or polyamide resin is provided inside the low-permeation or anti-permeation intermediate layer, the tube has an increased overall wall thickness, which leads to limiting the thickness of the intermediate layer, thereby limiting the anti-permeation function of the same. In addition, in the case where the innermost layer is formed of polyamide resin, the innermost layer may be less resistant to sour gasoline than the polybutylene naphthalate resin. Meanwhile, in the case where the innermost layer is formed of fluororesin, the innermost layer may exhibit a low detergent resistance, and may exhibit a low sealing characteristic because the fluororesin has a low friction coefficient and is highly slidable relative to a coupling or a metallic member being inserted into an open end of the tube.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a fuel transporting tube which exhibits an excellent resistance to permeation of not only gasoline but also alcohol-blended gasoline, an excellent detergent resistance, and an excellent hydrolysis resistance, and exhibit an excellent resistance to interlayer separation when being used in a high-temperature atmosphere.
The present invention provides a fuel transporting tube which has one or more of the technical features that are described below in respective paragraphs given parenthesized sequential numbers (1) to (17). Any feature which includes another feature shall do so by referring, at the beginning, to the parenthesized sequential number given to that feature. Thus, two or more of the following features may be combined, if appropriate. Each feature may be accompanied by a supplemental explanation, as needed. However, the following features and the appropriate combinations thereof are just examples to which the present invention is by no means limited.
(1) According to a first feature of the present invention, there is provided a fuel transporting tube comprising an inner layer which contacts a fuel being transported and which is formed of a polybutylene naphthalate resin; an outer layer which is provided radially outwardly of the inner layer and which is formed of a polyamide resin or a polyolefin resin; and an intermediate layer wh
Iio Shinji
Ito Hiroaki
Burr & Brown
Nolan Sandra M.
Tokai Rubber Industries Ltd.
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