Stock material or miscellaneous articles – Hollow or container type article – Polymer or resin containing
Reissue Patent
2000-02-16
2003-04-22
Dye, Rena (Department: 3627)
Stock material or miscellaneous articles
Hollow or container type article
Polymer or resin containing
C428S034500, C428S034700, C428S036200, C428S475800, C427S536000, C427S539000, C138S118100, C138S125000, C156S244130, C156S244170, C156S244230, C156S244240
Reissue Patent
active
RE038087
ABSTRACT:
TECHNICAL FIELD
This invention relates to a fuel hose for use in the fuel system of a motor vehicle or other equipment, particularly a fuel hose consisting of a tubular fluororesin inner ply and a thermoplastic resin or rubber outer ply with a high inter-ply bond strength, a method of producing it, and a vacuum plasma apparatus for use in said method.
PRIOR ART
Generally the fuel hoses used in the fuel systems of cars and other equipment have multi-ply structures consisting of various rubber and resin plies or layers. Among such multi-ply fuel hoses, the two-ply fuel hose consisting of a tubular fluororesin inner ply and a thermoplastic resin or rubber outer ply laminated on the peripheral surface of said tubular inner ply is in prevalent use. The rationale is that, being not only resistant to the common corrosive agents such as chemicals and gasoline but also resistant to the sour gasoline which forms on oxidation of gasoline (sour gasoline resistance), fluororesin is generally regarded as the optimal molding material for the inner ply of the hose which is directly exposed to the fuel. The thermoplastic resin or other outer ply mentioned above is provided as a reinforcing member of the hose for imparting wear resistance and other dynamic characteristics to the fuel hose.
In the manufacture of a fuel hose of the above-mentioned structure, an inner ply made of a special fluororesin, rather than a ply of ordinary fluororesin, which has a modified surface for lamination with said thermoplastic resin or other outer ply is employed. The reason for this is that because the bonding affinity of ordinary fluororesin for other structural materials is very low, said two plies cannot be firmly bonded using an adhesive alone. The fuel hose, in particular, is required to have an initial bond strength (bond strength prior to use) value of not less than 1.2 N/mm which is higher than the bond strength required of the ordinary resin hose. This is because, as far as the fuel hose for use typically in the fuel system of a motor vehicle is concerned, unless it has an initial bond strength value not below the above-mentioned level under the service conditions where a fuel such as gasoline flows down it, there is the risk of partial delamination of the tubular fluororesin inner ply from the outer ply. In the event such a partial exfoliation of the tubular fluororesin inner ply takes place, the tubular fluororesin inner ply may collapse in the vicinity of delamination so that its tubular (hollow) structure is no longer preserved but is occluded to prevent a smooth flow of gasoline or other fuel.
As examples of said surface-modified fluorine-containing resins, the following three (two) fluororesins are known.
(1) A fluororesin material whose surface has been etched with a sodium metal complex (e.g. one described in Ind. Eng. Chem., 50, 329, 1958)
(2) a fluororesin material whose surface has been roughened by sputtering (e.g. one described in JP Publication S-58-25742).
However, the above surface-modified fluororesin materials have various disadvantages. Thus, the fuel hose fabricated using the first-mentioned fluororesin (1) having a sodium metal complex-modified surface suffers aging in adhesion. This loss of adhesion is particularly remarkable when the hose is exposed to ultraviolet radiation. Moreover, since the above surface modification with a sodium metal complex requires the step of immersing fluororesin in a solution of the sodium metal complex and subsequently washing it, this technology has the drawback of being a time-consuming, complicated process. Moreover, the sodium metal complex solution is hazardous to health.
The latter fluororesin having a sputtered surface (2) does not provide for sufficient adhesion when the flowability of the adhesive is low and has the additional disadvantage that the recesses and projections formed by sputtering are easily evened out by friction. Therefore, in the manufacture of a fuel hose using the sputtered fluororesin material, its handling calls for sufficient care and this consideration detracts from the efficiency of production of the fuel hose.
Furthermore, these prior art fluororesins have the common problem that they provide for only poor adhesion when a thermoplastic resin or the like is directly bonded thereto without the aid of an adhesive. For the manufacture of a fuel hose using a fluororesin and a thermoplastic resin such as polyamide resin, not only the above-mentioned method of bonding the two resins with an adhesive but, at least theoretically, the method of heating the thermoplastic resin to achieve the necessary fusion can be employed. According to the latter thermal fusion technique, the step for application and drying of the adhesive can be dispensed with to reduce the production sequence and, in addition, since an organic solvent for dissolving the adhesive is not required, a safer working environment can be insured. Actually, however, the conventional surface-modified fluororesin materials provide for only poor adhesion by the thermal fusion technique, with the result that the above-mentioned inherent advantages of the technique cannot be exploited.
Meanwhile, paying attention to the atomic composition of the surface layer of a fluororesin, a fluororesin material having an adhesion-expressing atomic composition in the surface layer has been proposed (JP Publication H-2-54848). To be specific, the surface of a specified fluororesin is modified to bring the F/C ratio, i.e. ratio of the number of fluorine atoms (F) to the number of carbon atoms (C) and the O/C ratio, i.e. ratio of the number of oxygen atoms (O) to the number of carbon atoms (C), into specified ranges, respectively. With this surface-modified fluororesin, the above-mentioned drawbacks of the conventional fluororesins can be overcome. However, only a few kinds of fluororesins are available to which the surface modification by this technique can be successfully applied and, moreover, the technique has the disadvantage that the expression of adhesion cannot be uniformly obtained over a spectrum of fluororesins each having its own useful performance characteristics. Furthermore, the range of said F/C ratio and of said O/C ratio is very limited so that an elaborate, delicate control technology is essential for converging the surface of any fluororesin into said narrow ranges of atomic ratios, with the result that the production is inevitably complicated.
Thus, because of the lack of sufficient adhesion of the prior art surface-modified fluororesins, fuel hoses manufactured using them are not possessed of the initial bond strength or green bond strength necessary for service. Moreover, the fuel hoses manufactured by the conventional production technologies are not free from problems in the aspects of work safety, production efficiency and cost. However, since the fuel hose having a fluororesin inner ply has a high performance quality and a long life as mentioned above, there is an ardent demand for a solution to the above-mentioned problems.
OBJECT OF THE INVENTION
This invention has for its object to provide a fuel hose having a sufficiently high initial bond strength of not less than 1.2 N/mm between the fluororesin inner ply and the thermoplastic resin or other ply, which is easy to manufacture and free from problems in work safety and cost, a method for production of the hose, and a vacuum plasma apparatus for use in the method.
DISCLOSURE OF THE INVENTION
Having been developed to accomplish the above object, this invention is directed, in a first aspect, to a fuel hose having a laminated structure comprising a tubular or hollow fluororesin inner ply and, as laminated onto the peripheral surface thereof, a thermoplastic resin or rubber outer ply, said tubular fluororesin inner ply having been molded from a fluororesin having an F/C ratio, i.e. a ratio of the number of fluorine atoms (F) to the number of carbon atoms (C), of ≦1.6 and said outer ply overlying said tubular fluororesin inner ply having been treated to present the following layer (A).
(A) a layer having a dist
Daikai Eiichi
Ito Hiroaki
Kato Kazuhiro
Murakami Koyo
Yokoe Katsuhiko
Armstrong Westerman & Hattori, LLP
Dye Rena
Tokai Rubber Industries Ltd.
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