Abstract:
A fuel filler and fuel vent hose having reduced fuel permeation, comprises an elastomeric inner layer, a fluoropolymer barrier layer formed from tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride terpolymer; tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride-perfluorovinyl ether quadpolymer; or blends of two or more tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymers or terpolymers on the elastomeric inner layer, and a chlorinated polyethylene backing layer. Optionally, the fuel filler and fuel vent hose include an adhesive layer between the fluoropolymer barrier layer, and the chlorinated polyethylene backing layer, and an optional reinforcement layer as well as an additional outer cover layer. A method of forming such tubular structures is also included.

Description:
[0001]    This application is a continuation-in-part of U.S. patent application Ser. No. 11/513,371, filed Aug. 30, 2006. 
     
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to the field of multilayer hoses, and particularly to the field of flexible multiplayer polymeric hoses for use in fuel, chemical and vapor transport 
         [0003]    Flexible polymeric hoses are generally used in a variety of uses such as automobile fuel feed hoses, fuel vent hoses, torque converter hoses, power steering hoses, air conditioner hoses, brake fluid hoses, industrial hydraulic hoses and compressed gas hoses, refrigerator hoses, garden hoses, propane gas hoses, etc. Various types of tubing construction have been employed to meet the needs of the various applications of hoses. For example, multilayer tubular structures are commonly used in the automotive industry as fuel and chemical transport hoses and fuel vent hoses. Choosing the right combination of materials used in the construction of such hoses is becoming more difficult due to environmental regulations that severely limit the amount of fuel vapor that can permeate from the fuel system of a motor vehicle. Typically, fuel filler and vent hoses are multilayer tubular structures constructed of a natural or synthetic rubber material such as a conductive nitrile, e.g., acrylonitrile rubber, a fluoropolymer barrier layer such as a tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride terpolymer (THV) barrier layer, a nitrile backing layer, a reinforcement layer and a chlorinated polyethylene (CPE) cover layer. 
         [0004]    The overall cost and effectiveness of such hoses has proven to be somewhat disappointing. Therefore, there is a need for a fuel and chemical transport hose as well as a fuel vent hose that is more economical to produce and which exhibits improved properties. 
       SUMMARY OF THE INVENTION 
       [0005]    According to the present invention there is provided an improved multilayer tubular structure which is less costly to manufacture than prior multilayer fuel transport hoses and, in some cases, like fuel-alcohol blends, the fuel resistance, heat resistance and ozone resistance of chlorinated polyethylene is superior to the nitrile currently used as a backing layer. In addition to reduced permeability, the hose has adequate strength and durability over long periods of time, and is resistant to chemical degradation by the fluids being transported therein. 
         [0006]    The elastomeric inner layer of the tubular structure of the invention is a nitrile elastomer such as acrylonitrile elastomer, or other elastomeric material such as chlorinated polyethylene and the like. Preferably, the elstomeric inner layer is an acrylonitrile-butadiene rubber or chlorinated polyethylene (CPE). 
         [0007]    Typically, fuel filler and vent hoses have been manufactured from multilayer tubular structures constructed of a natural or synthetic rubber material such as a conductive nitrile, e.g., acrylonitrile rubber, employing a nitrile backing layer. It has now been found that chlorinated polyethylene is more economical than nitrile elastomers as a backing layer, and the chlorinated polyethylene offers improved fuel resistance and heat resistance over nitrile elastomers. 
         [0008]    In those instances where the tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride (THV) is adjacent the chlorinated polyethylene layer, it is advantageous to use an adhesive, such as an amine adhesive to provide sufficient adhesion between the chlorinated polyethylene and the fluoropolymer barrier layer as set forth below. 
         [0009]    Since it is well known in the industry that hoses used to transport fuels employ a conductive agent or otherwise exhibit conductive characteristics in order to dissipate any electrical buildup, which may occur during the flow of fuel through the hose, the inner layer of the hose of the present application preferably, contains therein such a conductive agent. 
         [0010]    In a first manifestation, the multilayered tubular structure of the present invention comprises: an elastomeric nitrile inner layer, a fluoropolymer barrier layer, an adhesive layer, and a chlorinated polyethylene (CPE) cover layer. 
         [0011]    In a second manifestation, the multilayered tubular structure of the present invention comprises: an elastomeric nitrile inner layer, a fluoropolymer barrier layer, a reinforcement member, and a chlorinated polyethylene cover layer. 
         [0012]    In a third manifestation, the multilayered tubular structure of the present invention comprises an elastomeric nitrite inner layer, a fluoropolymer barrier layer, an adhesive layer, a chlorinated polyethylene backing layer, a reinforcement, and a cover layer. 
         [0013]    In a fourth manifestation, the multilayered tubular structure of the present invention comprises a chlorinated polyethylene inner layer, an adhesive layer, a fluoropolymer barrier layer, and a cover layer. 
         [0014]    In a fifth manifestation, the multilayered tubular structure of the present invention comprises a chlorinated polyethylene inner layer, a first adhesive layer, a fluoropolymer barrier layer, a second adhesive layer, and a chlorionated polyethylene cover layer. 
         [0015]    In a sixth manifestation, the multilayered tubular structure of the present invention comprises a chlorinated polyethylene inner layer, an adhesive layer, a fluoropolymer barrier layer, a reinforcement member, and a cover layer. 
         [0016]    In a seventh manifestation, the multilayered tubular structure of the present invention comprises a chlorinated polyethylene inner layer, a first adhesive layer, a fluoropolymer barrier layer, a second adhesive layer, and a chlorinated polyethylene cover layer. 
         [0017]    In an eighth manifestation, the multilayered tubular structure of the present invention comprises a chlorinated polyethylene inner layer, a first adhesive layer, a fluoropolymer barrier layer a second adhesive layer, a chlorinated polyethylene backing layer, a reinforcement member, and a cover layer. 
         [0018]    Typically, the hoses of present invention are useful as automobile fuel vent hoses, fuel filler hose, vapor lines and fuel feed lines. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]      FIG. 1  is a perspective cutaway view illustrating a first manifestation of a tubular member of the present invention; 
           [0020]      FIG. 2  is a perspective cutaway view illustrating a second manifestation of a tubular member of the present invention; 
           [0021]      FIG. 3  is a perspective cutaway view illustrating a third manifestation of a tubular member of the present invention; 
           [0022]      FIG. 4  is a perspective cutaway view illustrating a fourth manifestation of a tubular member of the present invention; 
           [0023]      FIG. 5  is a perspective cutaway view illustrating a fifth manifestation of a tubular member of the present invention; 
           [0024]      FIG. 6  is a perspective cutaway view illustrating a sixth manifestation of a tubular member of the present invention; 
           [0025]      FIG. 7  is a perspective cutaway view illustrating a seventh manifestation of a tubular member of the present invention; and 
           [0026]      FIG. 8  is a perspective cutaway view illustrating an eighth manifestation of a tubular member of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0027]    With respect to the drawings,  FIG. 1  is a tubular structure in accordance with a first embodiment of the invention where an inner tubular structure  10  is made from a nitrile polymeric material  11 , a fluoropolymer barrier layer  12  surrounding the outer surface of the nitrile layer  11 , an adhesive layer  13  on the surface of the fluoropolymer barrier layer  12 , and a chlorinated polyethylene cover  14  on top of the adhesive layer  13  and forming the outside layer of the tubular structure  10 . 
         [0028]      FIG. 2  is a tubular structure in accordance with a second embodiment of the invention where a tubular structure  20  is made from a nitrile material  21 , a fluoropolymer barrier layer  22  surrounding the outer surface of the nitrile layer  21 , a reinforcement layer  23  surrounding the fluoropolymer barrier layer  22 , and a chlorinated polyethylene outer cover  24  surrounding the reinforcement layer and forming the outside layer of the tubular structure  20 . 
         [0029]      FIG. 3  is a tubular structure in accordance with a third embodiment of the invention where a tubular structure  30  is made from a conductive nitrile material  31 , a fluoropolymer barrier layer  32  on the outer surface of the conductive nitrile material  31 , an adhesive layer  33  on the outer surface of the fluoropolymer barrier layer  32 , a chlorinated polyethylene backing layer  34  surrounding the outer surface of the adhesive layer  33 , a reinforcement layer  35  surrounding the chlorinated polyethylene backing layer  34 , and a chlorinated polyethylene outer cover layer  36  surrounding the reinforcement layer  35  and forming the outside layer of the tubular structure  30 . 
         [0030]      FIG. 4  is a tubular structure in accordance with a fourth embodiment of the invention where a tubular structure  40  is made from a conductive chlorinated polyethylene material  41 , a adhesive layer  42  surrounding the conductive chlorinated polyethylene inner layer  41 , a fluoropolymer barrier layer  43  surrounding the adhesive layer  42  adhesive layer  42 , and a cover layer  44  surrounding the fluoropolymer barrier layer  43  and forming the outside layer of the tubular structure  40 . 
         [0031]      FIG. 5  is a tubular structure in accordance with a fifth manifestation of the invention where a tubular structure  50  is made from a conductive chlorinated polyethylene material  51 , a first adhesive layer  52  surrounding the chlorinated polyethylene inner layer  51 , a fluoropolymer barrier layer  53  surrounding the first adhesive layer  52 , a second adhesive layer  54  surrounding the fluoropolymer barrier layer  53 , and a chlorinated polyethylene cover layer  55  surrounding the second adhesive layer  54  and forming the outside layer of the tubular structure  50 . 
         [0032]      FIG. 6  is a tubular structure in accordance with a sixth manifestation of the invention where a tubular structure  60  is made from a conductive chlorinated polyethylene material  61 , an adhesive layer  62  surrounding the chlorinated polyethylene inner layer  61 , a fluoropolymer barrier layer  63  surrounding the adhesive layer  62 , a reinforcement member  64  surrounding the fluoropolymer barrier layer  63 , and a cover layer  65  surrounding the second adhesive layer  64  and forming the outside layer of the tubular structure  60 . 
         [0033]      FIG. 7  is a tubular structure in accordance with a seventh manifestation of the invention where a tubular structure  70  is made from a conductive chlorinated polyethylene material  71 , a first adhesive layer  72  surrounding the chlorinated polyethylene inner layer  71 , a fluoropolymer barrier layer  73  surrounding the first adhesive layer  72 , a second adhesive layer  74  surrounding the fluoropolymer barrier layer  73 , and a chlorinated polyethylene cover layer  75  surrounding the second adhesive layer  74  and forming the outside layer of the tubular structure  70 . 
         [0034]      FIG. 8  is a tubular structure in accordance with a sixth manifestation of the invention where a tubular structure  80  is made from a conductive chlorinated polyethylene material  81 , a first adhesive layer  82  surrounding the chlorinated polyethylene inner layer  81 , a fluoropolymer barrier layer  83  surrounding the first adhesive layer  82 , a second adhesive layer  84  surrounding fluoropolymer barrier layer  83 , a chlorinated polyethylene backing layer  85  surrounding the second adhesive layer  84 , a reinforcement member  86  surrounding the chlorinated polyethylene layer  85 , and a cover layer  87  surrounding the reinforcing layer  86  and forming the outside layer of the tubular structure  80 . 
         [0035]    Typically, the inner layer of the tubular structure is an elastomeric or rubber material such as a nitrile or chlorinated polyolefin, e.g., chlorinated polyethylene. While other conventional elastomeric materials may be used if desired, the inner layer, preferably, is either an acrylonitrile-butadiene polymer or a chlorinated polyethylene. Where a chlorinated polyethylene is employed in the tubular structure of the present invention, an adhesive material may be advantageously applied between the chlorinated polyethylene layer and the fluoropolymer layer. 
         [0036]    The barrier layer of the tubular structure is a fluoropolymer that prevents or reduces the permeation of fuel, chemical and vapor through the barrier layer. Typically, the barrier layer is a fluoropolymer containing polymerized units of tetrafluoroethylene, hexafluoropropylkene and vinylidene fluoride. Preferably, the fluoropolymer is a tetrafluoroethylene-hexafluoropropylene-vinylidene terpolymer (THV); a fluoroquad polymer derived from (i) tetrafluoroethylene (ii)hexafluoropropylene (iii) vinylidene fluoride and (iv) a perfluorovinyl ether; or a blend of about 20 to 80 weight percent of a first fluorointerpolymer having a fluorine content of about 65 to 73 weight percent with about 80 to 20 weight percent of a second fluorointerpolymer having a fluorine content of about 70 to 75 weight percent, wherein said first fluorointerpolymer is a copolymer or terpolymer formed by the copolymerization of two or more monomers selected from the group consisting of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride, and said second fluoropolymer is a terpolymer formed by the copolymerization of tetrafluoroethylene, hexafluoropropylene, and vinylidene fluoride, wherein said first fluorointerpolymer exhibits elastomeric characteristics and said second fluorointerpolymer exhibits thermoplastic characteristics. Such fluoropolymer blends are more fully described in U.S. Pat. No. 6,203,873, the contents of which is incorporated herein by reference thereto. 
         [0037]    The reinforcement materials useful in the present invention are materials which afford physical strength to the finished hose. Typically, the reinforcement member is a plurality of synthetic or natural fibers selected from the group consisting of glass fibers, cotton fibers, polyamide fibers, polyester fibers, rayon fibers and the like. Preferably, the reinforcement material is an aromatic polyamide such as Kevlar or Nomex, both of which are manufactured by DuPont. The reinforcing materials may be knitted, braided or spiraled to form the reinforcement member. In a preferred aspect of the invention, the reinforcing material is spiraled. While the reinforcement member may be a preferred component of the present hose structure, it is not critical in every application. Therefore, the reinforcement member may or may not be used in the manufacture of certain hoses depending on the requirements of the manufacturer. 
         [0038]    Typically, the inner layer of the tubular structure contains a conductive material such as metal or carbon. Preferably, the conductive material is carbon in the form of carbon black, but may be any conductive agent or combination of conducting agents commonly recognized in the industry to provide conductivity to a rubber or plastic material. Examples of such conductive agents include elemental carbon in the form of carbon black and carbon fibrils, metals such as copper, silver, gold, nickel, and alloys or mixtures of such metals. The use of such conductive agents is known in the art to dissipate static electricity in the transportation of a fluid through the tubular structure. Non-conducting elastomeric polymer materials may be employed as the inner layer in applications where dissipation of static electricity is not required. 
         [0039]    The outer cover is a protective layer of any of the commercially recognized materials for such use such as elastomers, thermoplastic polymers, thermosetting polymers, and the like. Typically, the protective cover layer is a synthetic elastomer having good heat resistance, oil resistance, weather resistance and flame resistance. Preferably, the outer cover layer is a synthetic elastomer selected from the group consisting of styrene-butadiene rubber (SBR); butadiene-nitrile rubber such as butadiene-acrylonitrile rubber, chlorinated polyethylene, chlorosulfonated polyethylene, vinylethylene-acrylic rubber, acrylic rubber, epichlorohydrin, e.g., Hydrin 200, a copolymer of epichlorohydrin and ethylene oxide available from DuPont, polychloroprene rubber (CR), polyvinyl chloride, ethylene-propylene copolymers (EPM), ethylene-propylene-diene terpolymer (EPDM), ultra high molecular weight polyethylene (UHMWPE), high density polyethylene (HDPE), and blends thereof. Preferably, the cover layer is chlorinated polyethylene. 
         [0040]    In accordance with the present invention, an adhesive material is typically employed between the chlorinated polyethylene inner tubular structure and the fluoropolymer barrier layer and between the fluoropolymer barrier layer and the chlorinated polyethylene backing layer or outer cover layer of the hose in order to prevent or reduce the likelihood of the layers separating during use. 
         [0041]    Other additives such as antioxidants, fillers, plasticizers, metal oxides/hydroxides, processing aids, crosslinking agents, co-agents etc. may be employed in amounts and methods known in the art to provide their desired effects. 
         [0042]    The tubular structures of the present invention are formed by known methods such as extruding the various layers using simultaneous, extrusion, tandum extrusion, or coextrusion. Typically, the hose of the present invention are produced by separate or tandum extrusion for versatility and economic reasons. 
         [0043]    Having described the invention in detail and by reference to preferred embodiments thereof, it will be apparent to those skilled in the art that modifications and variations are possible without departing from the scope of the invention as defined in the appended claims.