Stock material or miscellaneous articles – Hollow or container type article – Polymer or resin containing
Reexamination Certificate
1998-06-29
2002-11-19
Nolan, Sandra M. (Department: 1772)
Stock material or miscellaneous articles
Hollow or container type article
Polymer or resin containing
C138S137000, C428S036900, C428S036910, C428S420000, C428S421000, C428S474400, C525S064000, C525S066000, C525S068000, C525S072000, C525S902000
Reexamination Certificate
active
06482482
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to vessels and transport lines for containing hydrocarbon fluids.
BACKGROUND OF THE INVENTION
Motorized transportation vehicles, e.g. automobiles, trucks, and airplanes, all have transportation lines and vessels for containing the on-board hydrocarbon fluids during transportation and treatment of the fluids, respectively. The fluids can be liquid or vapor or mixture thereof, and the task of containment includes preventing permeation of the fluid through the structure defining the transportation lines and vessels. The transportation lines are generally tubular structures and include such lines as fuel line hose, fuel filler hose, sometimes called jumper hose, fuel vapor lines, lines for returning fuel combustion products to combustion, lines for transporting alcohol containing liquid between washer fluid reservoir and washer spray nozzles, and antifreeze lines. Vessels used on board the vehicle for treatment of the fluid are generally cylindrical structures, with one end closed and with an inlet for the untreated fluid and an outlet for treated fluid, such as carbon canisters for scrubbing fuel vapor from inlet fluid, and oil and fuel filters.
Current materials of construction are primarily of metal, but metal has the disadvantage of being corroded by the conditions of use of the vehicle or of excessive cost when non-corrosive metals or metal systems are used which resist corrosion and of adding weight to the vehicle. Polyamide has been used in some fuel line hose applications, but polyamide suffers from excessive hydrocarbon vapor permeability. Fluoropolymers have high vapor impermeability. U.S. Pat. No. 5,500,257 discloses composite fuel line in which the inner layer is made of fluoropolymer and the outer layer is made of polyamide, to provide the impermeability and strength, respectively, to the composite fuel line. The fluoropolymer inner layer is extruded first, followed by surface treatment of the outer surface of the fluoropolymer tubular extrudate and extrusion of the polyamide outer outer later onto the surface treated inner layer.
SUMMARY OF THE INVENTION
The present invention combines the strength of polar polymers such as polyamide and polyester and impermeability of fluoropolymer into a single layer as material of construction for lines and vessels for on-board transport and treatment of hydrocarbon fluid, and for handling such fluid in related functions such as servicing and delivery. Thus, the present invention can be described as vessels and transport lines for containment of hydrocarbon fluids for motorized transportation vehicles, the structure of said vessels and transport lines comprising a blend of polar-grafted fluoropolymer dispersed in polar polymer which is incompatible with said fluoropolymer prior to polar grafting of said fluoropolymer, said polar polymer providing strength to said structure and said polar-grafted fluoropolymer dispersed therein providing improved impermeability of said structure to said hydrocarbon fluids, whereby said vessels and transport lines are able to contain said hydrocarbon fluids.
The transport lines and vessels include those lines and vessels described above and can have similar construction, e.g., tubular in the case of transport lines and cylindrical housings (canisters) in the case of vessels. Thus, the present invention includes such specific on-board fluid handling products as fuel line hose, fuel filler hose, vapor return hose, carbon canisters, and oil filter housings.
The aforesaid blend will typically contain 3 to 43 vol % of the dispersed fluoropolymer and can be used as the sole material of construction of the structure defining the line or hose, depending on the particular hydrocarbon fluid being handled to provide improved impermeability. Alternatively, the blend may form a layer of a multilayer structure defining the line or vessel. For example, such structure can comprise an inner layer of fluoropolymer and the blend forms an outer layer, with the dispersed polar-grafted fluoropolymer in the blend layer causing the two layers to adhere together without any surface treatment of the inner layer. Thus, such composite structure can be made by simultaneous formation of both layers, i.e., by coextrusion whereby the molten layers adhere to one another as they come together outside of the extrusion die. Such composite structure can be coextruded in the form of tubing or other shape that can be converted to the desired fluid handling articles, such as coextruded sheet which can be thermoformed into vessel shapes. Another alternative is to have the blend layer coextruded as an interlayer between simultaneously extruded inner and outer layers of fluoropolymer and polar polymer, respectively, with the blend layer thereby serving to adhere the inner and outer layers together.
DETAILED DESCRIPTION
A melt-mixed blend having a continuous phase (matrix) and a dispersed phase is the basic material of construction of the hydrocarbon fluid handling articles of the present invention. The continuous phase of the blend is a polar polymer that is not a fluoropolymer, while the dispersed phase is a polar-grafted fluoropolymer. The hydrocarbon fluid includes compounds that are hydrocarbon-based or hydrocarbon derivatives, e.g., hydrocarbon compounds containing heteroatoms. The fluid can contain some non-hydrocarbon components such as additives, but it is still primarily a hydroocarbon fluid. As conventional and as used herein, “fluid” encompasses liquid and gas.
The base fluoropolymer of the fluoropolymer component of the blend layer is by itself incompatible with the polar polymer matrix, i.e., when the two polymers are melt blended together such as in a twin-screw extruder, the resultant fluoropolymer dispersed phase is composed of rather large particles (domains), e.g. at least 2000 nm in average particle size, by virtue of the fluoropolymer preferring to associate with itself rather than the polar polymer during the blending process. Dispersed particle size is determined by transmission electron microscopy. Examples of fluoropolymers include a wide variety of fluoropolymers which are melt extrudable, such as indicated by a melt viscosity in the range of 0.5×10
3
to 60×10
3
Pa·s as normally measured for the particular fluoropolymer. The fluoropolymer is made from at least one fluorine-containing monomer, but may incorporate monomer which contains no fluorine or other halogen. Preferably at least one monomer contains hydrogen and in that regard the hydrogen/fluorine atomic ratio is preferably at least 0.1:1. The fluoropolymer, however, preferably contains at least 35 wt % fluorine. Fluorinated monomers include those which are fluoroolefins containing 2 to 8 carbon atoms and fluorinated vinyl ether (FVE) of the formula CY
2
═CYOR or CY
2
═CYOR′OR wherein Y is H or F and —R— and —R′— are independently completely fluorinated or partially fluorinated linear or branched alkyl and alkylene groups containing 1 to 8 carbon atoms. Preferred R groups contain 1 to 4 carbon atoms and are preferably perfluorinated. Preferred R′ groups contain 2 to 4 carbon atoms and are preferably perfluorinated. Hydrocarbon monomers that can be used include ethylene, propylene, n-butylene, and iso-butylene. Preferred fluoropolymers are the copolymers of ethylene with perhalogenated monomers such as tetrafluoroethylene (TFE) or chlorotrifluoroethylene (CTFE), such copolymers being often referred to as ETFE and ECTFE, respectively. In the case of ETFE, minor amounts of additional monomer are commonly used to improve properties such as reduced high temperature brittleness. Perfluoro(propyl vinyl ether) (PPVE), perfluoro(ethyl vinyl ether) (PEVE), perfluorobutyl ethylene (PFBE), and hexafluoroisobutylene (HFIB) are preferred additional comonomers. ECTFE may also have additional modifying comonomer. Other fluoropolymers that can be used include vinylidene fluoride (VF
2
) polymers including homopolymers and copolymers with other perfluoroolefins, particularly hexafluoropropyle
E. I. du Pont de Nemours and Company
Nolan Sandra M.
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