Patent Application
20060016499
The present invention relates to a flexible, kink resistant, fluid transfer hose construction that employs a flexible and abrasion-resistant protective jacket that demonstrates the necessary mechanical properties to be included under a crimped sleeve or collar of a hose coupling.
Hose assemblies for conveying corrosive or aggressive materials are known. For automotive applications, these assemblies are typically routed through crowded engine compartments that reach temperatures ranging from −40° C. to 175° C. and carry fluids such as fuel and brake fluid that have the potential to chemically erode, swell or otherwise degrade the interior of the hose assemblies. Thus, these assemblies have to be resistant to physical, thermal and chemical degradation. Moreover, these hose assemblies have to resist kinking during installation, use and service.
Hose assemblies that include an inner fluoropolymer (e.g., polytetrafluoroethylene (PTFE)) tube or cylindrical member surrounded by a loosely to tightly wound metallic (e.g., stainless steel) braid have been found to provide these necessary physical characteristics.
Abrasion-resistant materials have been used on these prior art braided hose assemblies as outer protective jackets for the purpose of protecting the metallic braid from e.g. corrosion and road hazards, and for the purpose of preventing the metallic braid from damaging or physically eroding nearby components in the engine compartment.
Unfortunately, the jacket materials used on these braided hose assemblies either do not demonstrate the necessary mechanical properties to include the material under the crimped sleeve or collar of a hose coupling or the jacketed hose assemblies fail to demonstrate the necessary flexibility and kink resistance.
By way of example, U.S. Pat. No. 5,622,394 to Soles et al. describes a flexible hose assembly comprising a plastic outer coating 54 where it is necessary to strip the coating 54 back from an end of the hose 32 prior to attaching an end fitting. As will be readily appreciated, abrasive tools used to strip the plastic coating 54 back from this area may damage the metallic braid. Moreover, such an operation is time-consuming and serves to expose the metallic braid to damaging chemicals at each end of the hose.
By way of further example, hose assemblies jacketed with HYTREL® polyester elastomers have been subjectively evaluated by automotive suppliers as being too stiff, while hose assemblies jacketed with DYNEON™ THV melt-processable fluoroelastomers, which are also stiff, are known to demonstrate poor kink resistance and to have a tendency to buckle, leading vehicle inspectors to believe that rupture of the hose is imminent.
A need therefore exists for a fluid transfer hose construction that is flexible and kink resistant and that employs a flexible and abrasion resistant protective jacket that demonstrates the necessary mechanical properties to be included under a crimped collar of a hose coupling.
It is therefore a primary object of the present invention to provide such a hose construction.
It is a more particular object to provide an abrasion resistant thermoplastic elastomeric material having improved flexibility for use as a protective jacket for such hose constructions.
It is another more particular object to provide a flexible, kink resistant, fluid transfer hose construction and assembly that are jacketed with such a thermoplastic elastomeric material.
The present invention therefore provides a flexible and abrasion resistant thermoplastic elastomeric material, which is suitable for use as a protective jacket on flexible, kink resistant, fluid transfer hose constructions, wherein the thermoplastic elastomeric material comprises a reaction product of:
The present invention further provides a method for preparing the thermoplastic elastomeric material described above, wherein the method comprises: mixing components (a) through (e), wherein components (d) and (e) are present in an amount sufficient to cure component (b); and then curing component (b).
The present invention also provides a flexible, kink resistant, fluid transfer hose construction comprising:
The present invention further provides a hose assembly comprising the above-referenced flexible, kink resistant, fluid transfer hose construction and coupling means.
Other features and advantages of the invention will be apparent to one of ordinary skill from the following detailed description and accompanying drawings.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. All publications, patent applications, patents and other references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting.
Particular features of the disclosed invention are illustrated by reference to the accompanying drawings in which:
FIGS. 2 to 4 are latitudinal cross-sectional views of preferred embodiments of the inventive hose construction; and
The hose construction of the present invention, which demonstrates a flexural modulus at 23° C. (as measured by ASTM D790) of less than or equal to about 330 MPa (preferably, less than or equal to about 320 MPa, and more preferably, from about 200 to about 320 MPa), may be used in a wide variety of applications. For example, in addition to static automotive applications (e.g., as a flexible component in a rigid brake line system) and dynamic automotive applications (e.g., as a “jounce” or flexible hose mounted to a wheel on a front steering axle), the inventive hose construction may be used in freezer, refrigerator and air-conditioning systems and in the manufacture of semi-conductors.
Referring now to the drawings in detail, the flexible, kink resistant, fluid transfer hose construction of the present invention is shown generally at 10. As best shown in
The heat and chemically resistant inner tube 12 of hose construction 10 can effectively accommodate a wide variety of aggressive or degrading fluids, is such as brake fluids, hydraulic oils and fuels. Inner tube 12, which preferably has a wall thickness ranging from about 0.13 millimeters (mm) to about 1.9 mm and an inner diameter ranging from about 2.5 mm to about 50.8 mm, can be made of any polymeric material that is extrudable or moldable and that has a compressive strength (as measured by ASTM D695) of from about 3.4 MPa to about 310 MPa. Such materials include fluorocarbon polymers, polyamides, polyethylene resins, polyesters, polyimides, polypropylene, polyvinylchloride, silicones, and mixtures thereof. Preferably, inner tube 12 is made of a fluorocarbon polymer such as PTFE, copolymers of tetrafluoroethylene and hexafluoropropylene (FEP), perfluroalkoxyl resins (PFA) and polymers of ethylene-tetrafluoroethylene (ETFE). PTFE, FEP and PFA are sold by E.I. DuPont De Nemours, Inc., Wilmington, Del., under the trademark TEFLON. ETFE is also sold by DuPont under the trademark TEFZEL. More preferably, inner tube 12 is made of PTFE.
The flexible and abrasion-resistant protective jacket 14 formed on inner tube 12 is prepared from a thermoplastic elastomeric material and demonstrates the necessary mechanical properties to be included under a crimped sleeve or collar of a hose coupling.
As will be readily appreciated, the ability to include protective jacket 14 in the crimp zone without promoting buckling along the length of the hose, increases the useful life of the hose by eliminating false indicators of imminent hose failures and by preventing damaging chemicals from accessing inner tube 12 or a reinforcing or barrier layer at each end of the hose. In addition, the cost of manufacture is decreased as a result of the elimination of the stripping operation.
In a preferred embodiment, the protective jacket 14 is a flame resistant, thermoplastic elastomeric material formed from optionally compatiblized polyamide (e.g., nylon) resins. Thermoplastic elastomeric materials formed from polyamide resins, which are suitable for use in the present invention, are described in U.S. Pat. No. 6,362,287 B1 to Chorvath et al., while thermoplastic elastomeric materials formed from compatibilized polyamide resins, which are also suitable for use in the present invention, are described in U.S. Pat. No. 6,362,288 B1 to Brewer et al.
In a more preferred embodiment, the thermoplastic elastomeric material used to form protective jacket 14 is a reaction product of:
In yet a more preferred embodiment, the thermoplastic elastomeric material is a reaction product of.
In a most preferred embodiment, the material used to form protective jacket 14 is a reaction product of:
Exemplary materials for use in this most preferred embodiment are identified below:
The thermoplastic elastomeric material used to form protective jacket 14 may be prepared in accordance with the teachings of U.S. Pat. No. 6,362,288 B1. In a preferred embodiment, the thermoplastic elastomeric material is prepared by compounding the component mixture in a twin-screw extruder, where components (d) and (e) are present in the mixture in amounts sufficient to cure component (b), pelletzing the compounded mixture, and then vacuum drying the pellets overnight at 80° C. The pellets may then be melt-blended and extruded over inner tube 12 and cured to form protective jacket 14. It is noted that protective jacket 14, upon curing will not adhere to inner tube 12.
The protective jacket 14 preferably has a wall thickness ranging from about 0.05 mm to about 2.54 mm and an inner diameter ranging from about 3.2 mm to about 19.0 mm or greater.
In a more preferred embodiment of the present invention, the flexible, kink resistant, fluid transfer hose construction 10 comprises: (1) a PTFE inner tube 12; and (2) a flexible and abrasion-resistant protective jacket 14 that comprises a flame resistant, thermoplastic elastomeric material formed from one or more compatiblized polyamide resins.
Hose construction 10 of the present invention may further comprise at least one reinforcing or barrier layer 16 prepared from reinforcing or barrier materials loosely or tightly braided, woven or wound about the exterior of inner tube 12. Materials suitable for use in layer 16 include metal (e.g., carbon, carbon steel, copper, brass, stainless steel and alloys thereof) and non-metal (e.g., polyester, nylon, aramid) reinforcing or barrier materials.
In two such embodiments, which are best shown in
Preferably, barrier layer 16 is a single-walled aluminum structure prepared in accordance with the methods described in U.S. Pat. No. 5,40,334 to O'Melia et al. and U.S. Pat. No. 5,531,841 to O'Melia et al.
More preferably, barrier layer 16 is prepared by dispersing a fluoropolymer in a chromate conversion coating and then by applying the resulting mixture to a strip of aluminum foil having a thickness of from about 0.025 to about 2.500 mm. The fluoropolymer/conversion coated aluminum strip is then either axially or helically wrapped around a preexisting fluoropolymer tube. The resulting construction is then heated to a temperature of about 350° C. for approximately 3 to 5 minutes. In a more preferred embodiment, the axially or helically wrapped aluminum foil strip is overlapped (e.g., 15 to 50% overlap) to cover any gaps or leak paths in the aluminum foil layer thereby further reducing permeation through hose construction 10.
In another embodiment (not shown), layer 16 is a reinforcing layer comprising an interwoven braid or a spiral winding of one or more synthetic fibrous materials. Such fibrous materials include, but are not limited to, aramid fibers, polyethylene fibers, poly(p-phenylene-2,6-benzobisoxazole) fibers, polyvinyl alcohol fibers, and mixtures thereof. Aramid yarns or fibers are sold by E. I. du Pont de Nemours and Company, 1007 Market Street, Wilmington, Del. 19898, under the trade designation KEVLAR synthetic aramid fiber, and by Teijin Shoji (USA), 42 W 39th St. Fl. 6, New York, N.Y. 10018-3809, USA, under the trade designation TECHNORA para-aramid fiber. Polyethylene fibers are available from Honeywell International Inc., 101 Columbia Road, Morristown, N.J. 07962, under the trade designation SPECTRA polyethylene fiber, and also from Toyobo Co., Ltd., DYNEEMA Department, 2-8, Dojimahama 2-chome, Kita-Ku, Osaka 530-8230, JAPAN, under the trade designation DYNEEMA SK60 polyethylene fiber. Poly(p-phenylene-2,6-benzobisoxazole) or POB fibers are also sold by Toyobo Co., Ltd., ZYLON Department, under the trade designation ZYLON PBO fibers, while polyvinyl alcohol fibers are sold by Kuraray America, Inc., 101 East 52nd Street, 26th floor, New York, N.Y. 10022, under the trade designation KURALON polyvinyl alcohol fibers.
In yet another embodiment, which is best shown in
Reinforcing or barrier layer 16 preferably has a wall thickness ranging from about 0.025 mm to about 2.000 mm and an inner diameter ranging from about 3.2 mm to about 100.0 mm.
Hose construction 10 of the present invention may include additional layers, which overlie the exterior surface of protective jacket 14. For example, in applications requiring higher pressure ratings, hose construction 10 may further comprise one or more additional reinforcing or barrier layers and, optionally, one or more additional flexible and abrasion-resistant protective jackets.
In a preferred process for preparing hose construction 10, a polymeric material is extruded to form an inner tube 12 having a wall thickness of from about 0.13 mm to about 1.9 mm and an inner diameter of from about 2.5 mm to about 50.8 mm. A reinforcing or barrier material may then be braided, weaved or wound about the exterior of inner tube 12 to form reinforcing or barrier layer 16. The pelletized thermoplastic elastomeric material is then melt-blended and extruded onto either the inner tube 12 or the reinforcing or barrier layer 16 and is then cross-linked using known techniques which include chemical and radiation cross-linking methods.
Referring now to
The hose assembly of the present invention, which comprises hose construction 10 and coupling means, demonstrates a balance of physical is properties. For example, the inventive hose assembly satisfies the minimum requirements set by the Automotive Industry, namely—(1) tensile pull strength—the ability to withstand a pull of at least about 1445 Newtons (N) (325 pounds), preferably, at least about 5382 N (1210 pounds), and more preferably, at least about 5471 N (1230 pounds), without separation of the hose from its end fittings (U.S. Department of Transportation (DOT) Motor Vehicle Safety Specification (MVSS) § 571.106 S5.3.4), (2) burst strength—the ability to withstand water pressures ranging from 27.6 to 34.5 MPa (4,000 to 5,000 psi) without rupture (U.S. DOT MVSS § 571.106 S5.3.2), and (3) impulse resistance—the ability to withstand at least 150 hot impulse cycles with a brake fluid heated to a temperature of 143° C. (295° F.). For this test, pressure is applied to the fluid and the hose at a level of 11 MPa (1600 psi) for one minute, the pressure is then released to substantially ambient pressure for one minute and the cycle repeated (Society of Automotive Engineers (SAE) J1401).
Preliminary testing of aramid-reinforced PTFE hose assemblies jacketed with either a HYTREL® polyester elastomer, a DYNEON® THV melt-processable fluoroelastomer or the silicone elastomeric material of the present invention has shown, as set forth below, that the hose assembly of the present invention demonstrates increased flexibility and improved tensile pull strength over these prior art hose assemblies.
1ASTM D790 (23° C.)
2U.S. DOT MVSS § 571.106 S5.3.4
While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. Thus, the breadth and scope of the present invention should not be limited by any of the exemplary embodiments.
This application claims priority from U.S. Provisional Patent Application Ser. No. 60/409,708, filed Sep. 9, 2002.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US03/27867 | 9/5/2003 | WO | 8/23/2005 |
