Abstract:
A fuel feed hose and a fuel vapor line hose having reduced fuel permeation comprises a conductive FKM inner tubular structure and a chlorinated polyethylene backing layer. The hose optionally contains an adhesive layer between the conductive FKM inner layer and the chlorinated polyethylene backing layer. Furthermore, the hose optionally contains a reinforcement member and a cover over the reinforcement member. 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. 11/513,384, 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 polymeric hoses for use in fuel feed and vapor lines 
         [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 feed and vapor lines. Choosing the right combination of materials used in the construction of such hoses is becoming more difficult due to environmental regulations, which severely limit the amount of fuel vapor that can permeate from the fuel system of a motor vehicle. Currently, fuel feed and vent lines are multilayer tubular structures constructed of a fluoropolymer (FKM) inner layer, a nitrile or epichlorohydrin (ECO) backing layer, a reinforcement layer, and a chlorinated polyethylene (CPE), chlorosulfonated polyethylene (CSM) or epichlorohydrin cover layer. 
         [0004]    The overall cost and effectiveness of such hoses has proven to be somewhat disappointing. Therefore, there is a need for fuel feed and vapor line hose which 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 fuel hose having a chlorinated polyethylene backing layer which is less costly to manufacture than prior multilayer fuel hoses. Furthermore, the multilayer hose of the present invention employing a chlorinated polyethylene backing layer exhibits superior fuel resistance compared to either the nitrile or epichlorohydrin materials currently used as a backing layer. In addition to reduced fuel resistance, the hose offers improved heat resistance and ozone resistance as well as sufficient strength and durability over long periods of service. 
         [0006]    Generally, the multilayer hose of the present invention comprises an inner fluoropolymer barrier layer, a reinforcement layer, a chlorinated polyethylene backing layer, and a cover layer. 
         [0007]    Since it is well known in the industry that hoses used to transport fuels contain 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 hose of the present application may contain such conductive agent. 
         [0008]    In those instances where the fluoropolymer is adjacent the chlorinated polyethylene layer, an adhesive that is effective to adhere a fluoropolymer to a chlorinated polyethylene is preferably used to adhere the fluoropolymer layer to the CPE layer. 
         [0009]    Typically, the hoses of the present invention are useful as an automobile fuel vent hose, fuel filler hose, vapor lines and fuel feed lines. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a perspective view illustrating a first embodiment of the invention; 
           [0011]      FIG. 2  is a perspective view illustrating a second embodiment of the invention; 
           [0012]      FIG. 3  is a perspective view illustrating a third embodiment of the invention; 
           [0013]      FIG. 4  is a perspective view illustrating a fourth embodiment of the invention; 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0014]    In a first embodiment, the hose of the present invention comprise: a conductive FKM fluoropolymer inner layer and a chlorinated polyethylene (CPE) backing layer on the conductive FKM fluoropolymer inner layer. 
         [0015]    In a second embodiment, the hose of the present invention comprises: a conductive FKM fluoropolymer inner layer, an adhesive layer on the conductive FKM fluoropolymer inner layer, and a chlorinated polyethylene backing layer on the adhesive layer. 
         [0016]    In a third embodiment, the hose of the present invention comprises a conductive FKM fluoropolymer inner layer, an adhesive layer, a chlorinated polyethylene (CPE) backing layer, a reinforcement layer, and a cover layer. 
         [0017]    In a fourth embodiment, the hose of the present invention comprises a conductive FKM fluoropolymer inner layer, a reinforcement layer and a chlorinated polyethylene (CPE) backing layer. 
         [0018]    With respect to the drawings,  FIG. 1  is a tubular structure in accordance with a first embodiment of the invention where a tubular structure  10  is made from a fluoropolymer inner layer  11  and a chlorinated polyethylene backing layer  12  on the fluoropolymer inner layer. 
         [0019]      FIG. 2  is a tubular structure in accordance with a second embodiment of the invention where a tubular structure  20  is made from a fluoropolymer inner layer  21 , an adhesive layer  23  surrounding the outer surface of the fluoropolymer inner layer  21 , and a chlorinated polyethylene backing layer  24 , and forming the outside layer of the tubular structure  20 . 
         [0020]      FIG. 3  is a tubular structure in accordance with a third embodiment of the invention where a tubular structure  30  is made from a fluoropolymer inner layer  31 , a chlorinated polyethylene backing layer  32  surrounding the fluoropolymer inner layer  31 , a reinforcement layer  33  surrounding the chlorinated polyethylene backing layer  32 , and a cover layer  34  surrounding the reinforcement layer  33 , and forming a cover layer  34  of the tubular structure  30 . 
         [0021]      FIG. 4  is a tubular structure in accordance with a fourth embodiment of the invention where a tubular structure  40  is made from a fluoropolymer inner layer  41 , a reinforcement layer  42  surrounding the fluoropolymer inner layer  41 , a chlorinated polyethylene backing layer  43  surrounding the reinforcement layer  42 , and a cover layer  44  surrounding the chlorinated polyethylene backing layer  43 , and forming a cover layer  44  of the tubular structure  40 . 
         [0022]      FIG. 5  is a tubular structure in accordance with a fifth embodiment of the invention where a tubular structure  50  is made from a conductive FKM fluoropolymer inner layer  51 , a fluoropolymer barrier layer  52  surrounding the conductive FKM inner layer  51 , an adhesive layer  53  surrounding the fluoropolymer barrier layer  52 , and a chlorinated polyethylene layer  54  surrounding the adhesive layer  53 . 
         [0023]      FIG. 6  is a tubular structure in accordance with a sixth embodiment of the invention where a tubular structure  60  is made from a conductive inner FKM inner layer  61 , a fluoropolymer barrier layer  62  surrounding the FKM inner layer  61 , an adhesive layer  63  surrounding the fluoropolymer barrier layer  62 , a chlorinated polyethylene layer  64  surrounding the adhesive layer  63 , a reinforcement member  65  surrounding the chlorinated polyethylene layer  65  and a cover  66  surrounding the reinforcement member layer  65   
         [0024]    Typically, the backing layer of prior tubular structures is a nitrile such as acrylonitrile-butadiene polymer, or an epichlorohydrin (ECO) material. It has been found that, in the manufacture of a fuel feed or vapor line hose, chlorinated polyethylene provides an improved and more cost efficient alternative to the nitrile or epichlorohydrin as the backing layer. 
         [0025]    The inner 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 inner layer is an FKM fluoroelastomer composition such as fluoroelastomeric tetrafluoroethylene-hexafluoropropylene-vinylidene terpolymers. Such FKM fluoroelastomers useful in the present invention are the FLUOREL fluoroelastomers available from Dyneon. 
         [0026]    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. 
         [0027]    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. 
         [0028]    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 layer is a synthetic elastomer having good heat resistance, oil resistance, weather resistance and flame resistance. Preferably, the outer cover 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 rubber (EP), 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. 
         [0029]    In accordance with the present invention, an adhesive material is typically employed between the fluoropolymer barrier layer and the chlorinated polyethylene barrier layer or outer cover layer of the hose in order to prevent or reduce the likelihood of the two layers separating during use. Typically, the adhesive material is a polyamine and, most preferably, the adhesive is polyallylamine. 
         [0030]    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. 
         [0031]    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 
         [0032]    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 defined in the appended claims.