MX2008006937A - High temperature thermoplastic power steering hose - Google Patents

Abstract

A hose (1) comprising a core tube (2) , a reinforcement layer (3) surrounding the core tube (4) , and a cover (4) surrounding the reinforcement layer, wherein at least one of the core tube (2) and cover (4) are made of a thermoplastic material comprising one or more thermoplastic polyether-polyester block copolymers, and said thermoplastic material has a Shore D hardness no less than about 60.

Description

HIGH TEMPERATURE THERMOPLASTIC ENERGY STEERING HOSE FIELD OF THE INVENTION The present invention relates extensively to thermoplastic hoses and, in particular, to reinforced thermoplastic hoses for high temperature acations, such as an energy steering hose.

BACKGROUND OF THE INVENTION Reinforced thermoplastic hoses have been used in a variety of fluid transfer acations. Those hoses have included a tubular core surrounded by one or more courses of reinforcement of natural or synthetic fiber and / or steel wire. The reinforcement courses, in turn, are protected by a surrounding external liner or cover which may be the same or different material than the central tube. The cover can also provide the hose with greater resistance to abrasion. Although they are easy to form, thermoplastic reinforced hoses have not been suitable for use at high temperatures under high performance conditions for extended periods of time. That is, conventional thermoplastic hoses have not been considered for use at temperatures greater than 121 ° C (250 ° F) and for prolonged periods of time of the order of 1000 hours or more. The energy management systems have therefore used formed metal tubing and flexible connector hoses made of thermosetting materials (rubber) that can withstand high operating temperatures of 148.8 ° C (300 ° F) for a period of time. Rubber hoses, however, are prone to deterioration over time, and thus require replacement before or after failure. High performance hoses have also been produced from other thermosetting material, but these hoses are often expensive, difficult to form and / or too hard and / or rigid.

SUMMARY OF THE INVENTION The present invention provides a thermoplastic hose, and particularly a hose reinforced with thermoplastic having high resistance to degradation by temperature, as well as chemical resistance, and is still easily formable when compared to the power steering hoses. or others of high performance of the prior art that are capable of operating at elevated temperatures, such as 148.8 ° C (300 ° F) or more, and at least about 121 ° C (250 ° F) or 126.6 ° C (260 ° F), for extended periods of time, such as 1000 hours or more. A hose according to the present invention is characterized by the use of material comprising one or more thermoplastic polyether-polyester block copolymers, ie block copolymers of alternating hard and soft segments connected by ester and ether bonds, which is characterized by a Shore D durometer hardness of at least about 60. Different grades of thermoplastic polyether-polyester block copolymers can be mixed to exhibit a combination of unique material properties, including but not limited to resistance retention. traction at high temperature, retention of traction and elongation properties after exposure to high temperature for prolonged periods of time, flexibility and formability. A hose according to the invention may be a monolayer hose, or a multilayer hose which may not be reinforced or reinforced. A multilayer hose can include a central tube and a cover with or without reinforcement interposed between them. The hose or hose layer can be made from a single grade of thermoplastic polyether-polyester block copolymer or a mixture of different grades of thermoplastic polyester-polyester block copolymers. In particular, the hose or hose layer can be made of a blend of a first thermoplastic polyether-polyester block copolymer characterized by a Shore D hardness of not less than about 65 and a second thermoplastic polyether-polyester block copolymer characterized by a Shore D hardness less than that of the first copolymer but not less than about 55, wherein the resulting mixed material from which the hose or hose layer is formed will have a Shore D hardness value between the values of the constituent copolymers. Even more particularly, the hose or hose layer can be formed from a mixture of from about 5% to about 95% by weight of the first copolymer and 5% up to about 95% by weight of the second copolymer, or from about 25% up to about 75% by weight of the first copolymer and from about 25% to about 75% by weight of the second copolymer, or from about 30% to about 40% by weight of the first copolymer and from about 60% to about 70% by weight of the second copolymer. A hose according to the invention may comprise an inner tubular layer and a tubular layer external surrounding the central tube, wherein at least one of the central tube and cover are made of thermoplastic material comprising one or more thermoplastic polyether-polyester block copolymers and the thermoplastic material has a Shore D hardness of not less than about 60. Internal tubular member can be made of the first thermoplastic material formulated to have a Shore D hardness of not less than about 65, and most preferably not less than about 70, and the outer tubular member can be made of a second thermoplastic material comprising one or more thermoplastic polyester-polyester block copolymers, the second thermoplastic material of the outer tubular member having a Shore D hardness less than the Shore D hardness of the thermoplastic material forming the inner tubular member but not less than about 64. Both, the layer tubular internal, like a central tube, and the outer tubular layer, like a cubi can be extruded, including co-extruded. A reinforcing layer may surround the inner tubular member, and the outer tubular layer may surround the reinforcing layer. The reinforcing layer may include one or more filaments wound helically around the inner tubular layer, with one or more filaments preferably selected from a group comprising nylon fibers, polyester fibers, aramid fibers, polyvinyl alcohol fibers, polyvinyl acetate fibers, polyolefin fibers, polyphenylene bezobisoxazole fibers, metal wires and combinations thereof. The thermoplastic material from which the inner and / or outer layers are formed may comprise from about 1% to about 5% thermal stabilizer. One or more block copolymers can have a melting temperature of at least 200 ° C and a Vicat softening temperature of at least 125 ° C. More preferably, the inner tubular member and / or the outer tubular member may have a melting temperature of at least 215 ° C and a Vicat softening temperature of at least 140 ° C, and more preferably at least 150 ° C. ° C, or a melting temperature of at least 200 ° C and a Vicat softening temperature of at least 125 ° C. In a preferred embodiment, the copolymers are Arnitel® EM740 and Arnitel® EM630. The invention also provides a method for forming a hose, by extruding one or more layers thereof from a thermoplastic material comprising one or more thermoplastic polyether-polyester block copolymers, with the thermoplastic material having a Shore D hardness of not less than about 60. In a particular embodiment, the method comprises the steps of extruding a central tube, applying a reinforcing layer around the central tube , and extrude a cover around the reinforcement layer. The above and other features of the invention are described hereinafter with reference to the appended figure.

BRIEF DESCRIPTION OF THE FIGURE In the appended figure, Figure 1 is a cut-away perspective view of a representative embodiment of a reinforced thermoplastic hose constructed in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION Certain terminology may be employed in the description below for convenience rather than for any limiting purpose. For example, the terms "forward", "backward", "right", "left", "upper" and "lower" designate directions in the figures to which reference is made, with the terms "inward", "internal", "internal", or "inside" and "out", "outside", "outside" or "outside" refer, respectively, to directions towards and away from the center of the referred element, and the terms "radial" and "axial" refer, respectively , to directions perpendicular and parallel to the central longitudinal axis of the referred element. Terminology of similar importance in addition to the words specifically mentioned above should also be considered as if they were used for purposes of convenience rather than in some limiting sense. A preferred embodiment of a composite hose construction according to the invention has particular application as an energy steering hose or other high performance hose capable of operating at elevated temperatures, such as approximately 148.8 ° C. (300 ° F) or higher, for prolonged periods of time, such as approximately 1000 hours or more. In addition, a preferred embodiment of the composite hose construction is capable of operating at high pressures, such as approximately 1500 psi (10.3 Pa) or more. It will be appreciated, however, that aspects of the present invention may find use in other hose constructions for a variety of general or other hydraulic fluid transfer applications. The use within those other applications therefore should be expressly considered within the scope of the present invention. A hose according to the invention may be a monolayer hose, or a multilayer hose which may not be reinforced or reinforced. The multilayer hose may include a central tube and a cover with or without reinforcement interposed between them. Referring now to Figure 1, an exemplary multilayer hose according to the present invention is generally shown at 1. The hose 1 comprises an inner layer such as the central tube 2, a reinforcing layer 3 surrounding the central tube, and an outer layer as the cover 4 surrounding the reinforcement layer. As discussed further below, an adhesive 5 may be used between the central tube and the reinforcing layer and / or an adhesive 6 may be used between the reinforcing layer and the cover, respectively. The hose may have additional layers without deviating from the general principles of the invention, such as an inner layer within the central tube as may be desired for some applications. The inner layer can be formed, for example, from a polyamide such as nylon. The hose 1 can be manufactured to any desired length using any suitable hose-making method, particularly where the inner central tube 2 is extruded to form a seamless, continuous tube, the reinforcing layer 3 is formed by one or more filaments that are wound helically around the inner central tube 2, and the cover is extruded on the reinforcing layer to form a continuous seamless cover. The hose can be formed in any desired length, and the hose, particularly to be used as an energy steering hose, will typically have an internal diameter of about 0.62 centimeters to about 5 centimeters (0.25 inches to about 2 inches), and a diameter externally from approximately 1.27 centimeters to approximately 5 centimeters (0.5 inches to approximately 2 inches). The hose can also have a typical total wall thickness in the range of about 0.12 centimeters to about 0.5 centimeters (0.05 inches to about 0.2 inches), with the thickness of the layer fluctuating, for example, from 0.05 centimeters to approximately 0.5 centimeters ( 0.02 inches to approximately 0.2 inches). The thermoplastic layers can be extruded, including coextruded in a known manner. The central tube 2 can be formed from one or more polyether-polyester block copolymers thermoplastics, in particular TPE-E (or COPE) consisting of block copolymers of alternating hard and soft segments connected by ester and ether linkages. The polymers of TPE-E and COPE, and also the copolymers of TPE-P, are high-performance thermoplastic elastomers that have excellent resistance over a wide range of temperatures, excellent dynamic properties, for example of formation and fatigue, high heat resistance , good resistance to chemical compounds, oils and fats, and dimensional stability. Preferred polyester / polyether block copolymers are polymers of polybutylene terephthalate -block-poly (tetramethylene oxide) such as Arnitel® EM 740, sold by DSM Engineering Plastics. Hytrel® polymers, sold by DuPont, meet the physical and chemical specifications set forth herein and may also be used. The core and / or cover made of the thermoplastic material possesses retention of resistance at high temperature and retention of strength and elongation properties after exposure to high temperatures for extended periods of time. Additional advantages of a preferred embodiment of hose according to the invention include formability, expansion properties desired, coloration ability, abrasion resistance, long hose lengths, and hose winding itself. Preferably, one or more thermoplastic polyether-polyester block copolymers has a melting temperature of at least 200 ° C (ISO 11357-1 / 3) and a Vicat softening temperature of at least 125 ° C (ISO 306). In one embodiment, the central tube and cover can have a melting temperature of at least 215 ° C and a Vicat softening temperature of at least 140 ° C, or at least 150 ° C. One or more thermoplastic polyether-polyester block copolymers may preferably have a Shore D hardness greater than 55, and thus the center tube has a Shore D hardness greater than 55. In a preferred embodiment, the tube is made of a mixture of a first thermoplastic polyether-polyester block copolymer having a Shore D hardness of not less than about 65 and a second thermoplastic polyether-polyester block copolymer having a lower Shore D hardness than that of the first polyether block copolymer. thermoplastic polyester, but not less than about 55. More preferably, the central tube is made of a mixture of a first polyether block copolymer. thermoplastic polyester having a Shore D hardness of not less than about 70 and a second thermoplastic polyether-polyester block copolymer having a Shore D hardness less than that of the first thermoplastic polyether-polyester block copolymer but not less than about 60. The blend may comprise from about 30% to 80% by weight of the first thermoplastic polyether-polyester block copolymer and from about 10% to about 50% by weight of the second thermoplastic polyether-polyester block copolymer. The blend may comprise from about 20% to about 40% by weight of the first thermoplastic polyether-polyester block copolymer and from about 55% to about 75% by weight of the second thermoplastic polyether-polyester block copolymer or vice versa. The blend may comprise about 32% ± 5% by weight of the first thermoplastic polyether-polyester block copolymer and about 65% ± 5% by weight of the second thermoplastic polyether-polyester block copolymer, or vice versa. The mixture may further comprise from about 1% to about 5%, such as 3% in weight of a thermal stabilizer. The mixture may also comprise other additives including colorants, UV protection additives, hydrolysis resistant additives and flame retardants. The thermal stabilizers can be selected from those known to those skilled in the art, including thermal stabilizer examples available from DSM Engineering Plastics for use with Arnitel® TPE, copper iodide (I) or organic stabilizers, N-isopropyl-N '- diphen-il-p-phenylenediamine (IPPD) or N, N '-diphenyl-p-phenylenediamine (DPPD). In a particular mixture, the first thermoplastic polyether-polyester block copolymer can be Arnitel® EM740 (Shore D 72) and the second thermoplastic polyether-polyester block copolymer can be Arnitel® EM630 (Shore D 60), both sold by DSM Engineering Plastics. The hardness of these materials typically varies by ± 3%. Of course it will be appreciated that other materials can be used, such as block copolymers similar to Hytrel® TPE-E sold by DuPont, for example, Hytrel® 7246, and mixtures thereof, which satisfy the characteristics set forth herein. The cover 4 can be formed of a copolymer or copolymers of different or similar thermoplastic polyether-polyester blocks. The previous discussion of the materials useful to form the tube central is equally applicable to the roof. The reinforcement layer 3, as mentioned above, may include one or more filaments entangled helically around the central tube. The filaments may be selected from a group comprising nylon fibers, polyester fibers, aramid fibers, polyvinyl alcohol fibers, polyvinyl acetate fibers, polyolefin fibers, polyphenylene bezobisoxazole fibers, metal wires and combinations thereof. More generally, the reinforcing layer may include two or more reinforcing layers. Each of the reinforcing layers can be conventionally formed as braided, woven, wound or, as shown, spiral, that is helically, wound from, for example, from 1 to about 60 ends of monofilament, continuous multifilament, i.e. , thread, threading, cord, rope, braid, ribbon, or crease, short "cut" strands of a fiber material. The fiber material, which may be the same or different in the layers, may be a natural or synthetic polymeric material such as nylon, cotton, polyester, polyamide, aramid, polyolefin, polyvinyl alcohol (PVA), polyvinyl acetate or polyphenylene bezobisoxazole (PBO), or a mixture, a steel, which can be stainless or galvanized, brass, zinc, or coated zinc or other metal wire or a mixture thereof. In a braided construction (not shown), which may also contain woven, rolled and / or knitted layers with additional spiral knitting, each of the reinforcement layers may be braided under tension at a separation angle of between, example, about 45-63 ° using for example between 12-96 supports each of which has for example 1 to about 32 ends of a denier of 420-6600 (decitex of 470-7400), aramid yarn multifilament, polyester , nylon, PVA, or PBO, including in particular nylon fiber with a 3600 denier having a mass / 304.8 m (1000 feet) in about 31.75 kg (70 pounds) up to about 72.57 kg (160 pounds), with six or seven ends, 24 supports, at a separation of approximately 3.55 to 4.83 cm (1.4 to 1.9 inches) and a braiding angle of approximately 50 ° to approximately 60 °. Adhesive layers 5 and 6, if used, may be of any suitable adhesive. An exemplary adhesive is Lord 7411 hot melt adhesive, but other adhesives may be used. Other means can also be used to join the layers together, such as by fusion, mechanically, chemically or adhesively, as already was mentioned, or a combination thereof. As it was anticipated that certain changes may be made in the present invention, without departing from the precepts implied herein, it is intended that all material contained in the foregoing description be construed as illustrative and not in a limiting sense. All references cited herein are expressly incorporated by reference.

Claims (20)

1. NOVELTY OF THE INVENTION Having described the invention as above, property is claimed as contained in the following: CLAIMS 1. A hose, characterized in that it comprises one or more tubular layers, at least one layer of a first thermoplastic material comprising one or more thermoplastic polyether-polyester block copolymers, and the thermoplastic material having a Shore D hardness not being made. less than about 60. The hose according to claim 1, characterized in that the first thermoplastic material comprises a mixture of a first thermoplastic polyether-polyester block copolymer characterized by a Shore D hardness of not less than about 65 and one second polyether-polyester thermoplastic block copolymer characterized by a Shore D hardness lower than that of the first thermoplastic polyether-polyester block copolymer but not less than about 55. 3. The hose according to claim 1, characterized in that the first material thermoplastic comprises a mixture of a first copolymer of b thermoplastic polyether-polyester ponds characterized by a Shore D hardness of not less than about 70 and a second thermoplastic polyether-polyester block copolymer characterized by a lower Shore D hardness than that of the first thermoplastic polyether-polyester block copolymer but not less than about 60. 4. The hose according to claim 2 or claim 3, characterized in that the mixture comprises from about 5% up to about 95% by weight of the first copolymer and about 5% up to about 95% by weight of the second copolymer. The hose according to claim 2 or claim 3, characterized in that the mixture comprises from about 25% to about 75% by weight of the first copolymer and from about 25% to about 75% by weight of the second copolymer. The hose according to claim 2 or claim 3, characterized in that the mixture comprises from about 30% to about 40% by weight of the first copolymer and from about 60% to about 70% by weight of the second copolymer. 7. The hose in accordance with any of claims 2-6, characterized in that the first copolymer is Arnitel® EM740 and the second copolymer is Arnitel® EM630. The hose according to any of the preceding claims, characterized in that it comprises an inner tubular layer and an outer tubular layer surrounding the central tube, where at least one of the central tube and the cover are made of the first thermoplastic material. The hose according to claim 8, characterized in that the inner tubular member is made of the first thermoplastic material formulated to have a Shore D hardness of not less than about 65, and most preferably not less than about 70. 10. The hose according to claim 8 or claim 9, characterized in that the outer tubular member is made of a second thermoplastic material comprising one or more thermoplastic polyether-polyester block copolymers, and the second thermoplastic material of the outer tubular member has a Shore D hardness less than the Shore D hardness of the first thermoplastic material forming the internal tubular member but not less than about 64. 11. The hose according to any of claims 8-10, characterized in that both of the inner and outer tubular layers are extruded. The hose according to any of claims 8-10, characterized in that it further comprises a reinforcing layer surrounding the internal tubular member, and where the external tubular layer surrounds the reinforcing layer. The hose according to claim 12, characterized in that the reinforcing layer includes one or more filaments wound helically around the inner tubular layer, one or more filaments being preferably selected from a group comprising nylon fibers, polyester fibers, aramid fibers, polyvinyl alcohol fibers, polyvinyl acetate fibers, polyolefin fibers, polyphenyl bezobisoxasol fibers, metal wires and combinations from the same. The hose according to any of claims 8-13, characterized in that the outer tubular layer has an outer surface defining a more external surface of the hose. 15. The hose according to any of claims 8-14, characterized in that the inner tubular layer has an internal surface that defines a more internal surface of the hose. The hose according to any of the preceding claims, characterized in that the first thermoplastic material comprises from about 1% to about 5% by weight of a thermal stabilizer. The hose according to any of the preceding claims, characterized in that the first thermoplastic material has a melting temperature of at least 200 ° C and a Vicat softening temperature of at least 125 ° C. The hose according to any of the preceding claims, characterized in that the first thermoplastic material has a melting temperature of at least 215 ° C and a Vicat softening temperature of at least 140 ° C, and more preferably the minus 150 ° C 19. The hose according to any of the preceding claims, capable of operating at a temperature of at least 148.8 ° C (300 ° F) for 1000 hours or more. A method for manufacturing a hose, characterized in that it comprises the steps of extruding a central tube, applying a reinforcement layer around the central tube, and extruding a cover around the layer of reinforcement, where at least one of the central tube and the cover are made of a thermoplastic material comprising one or more thermoplastic polyether-polyester block copolymers, the thermoplastic material has a Shore D hardness of not less than about 60.